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Few things are as poignant and gripping as a dead creature. The carcass of a slaughtered

elephant can move people to action far more readily than the eroded land on

which it died. Even a truckload of logs is more likely to catch people’s attention than

the fumes generated by the truck. Of course, people kill other organisms all the time.

It is just that the most provocative examples – killing other sentient beings, especially

mammals and birds – are usually well hidden behind the doors of slaughter houses.

The closest most of us come to killing is swatting flies, weeding a garden, or giving

our dog a flea bath. Even at the grocery store, with its huge arrays of dead plants and

animals and their products, we are unlikely to think about the organisms that die to

feed us. Intellectually, most people can accept the killing of other creatures for human

well-being until it gets out of hand, until people start overexploiting other species.

Then, our emotions join with our intellect to decry this threat to biological diversity.

There is a tendency to think that overexploitation (which we can define as human

overuse of a population of organisms to an extent that threatens its viability or significantly

alters the natural community in which it lives) is a relatively new phenomenon.

It is a romantic notion that throughout most of our span on earth we have lived

in harmony with nature. This view is rather naive, as we will see in some examples of

past overexploitation.

The Long History of Overexploitation

After the most recent glaciation the grasslands of central North America harbored an

extraordinary array of large mammals. The diversity of antelopes, horses, cheetahs,

giant ground sloths, mammoths, mastodonts, and others easily rivaled the large

mammal fauna of Africa today (Fig. 9.1). However, about 11,000 years ago, at the

end of the Pleistocene epoch, they disappeared; 34 genera of large mammals became

extinct in less than 1000 years, while 40 more became extinct in South America

(Martin 1984; Martin and Steadman 1999). This is a massive die-off when you consider

that only 20 large mammal genera had become extinct in North America over

the previous three million years. Is it a coincidence that so many large mammals went

extinct shortly after the time that humans, crossing from Siberia to Alaska, probably

first arrived in the Western Hemisphere? Paul Martin, an anthropologist, thinks not

and has argued in many articles and books that overhunting was primarily responsible

for these extinctions. In contrast, Martin’s critics have argued that the extinctions

were mainly the result of significant climate change (e.g. Graham and Lundelius

CHAPTER 9

Overexploitation

1984). Probably the full explanation lies in a complex amalgam of overkill, climate

change, and other possible factors such as disease and human-set fires (Barnosky

et al. 2004). Nevertheless, it seems highly likely that overhunting was more important

than climate change because the same story – humans arrive, large animals go

extinct – has now been told in many other locations where climate change was clearly

not responsible (Burney and Flannery 2005).

The best evidence that overhunting by early people has eliminated some species

comes from islands. On many remote islands, birds evolved in the absence of mammalian

predators, sometimes losing their ability to fly in the process. When people

arrived on these islands, they found easy prey. For example, when Polynesians, now

known as Maoris, arrived in New Zealand in about 1200 CE, the islands had 11

species of moas, a group of flightless birds ranging in size from a turkey to far

larger than an ostrich (Fig. 9.2) (Anderson 1989). By the time Europeans colonized

the islands in the eighteenth century, the moas were all gone, along with five

species of rail and six waterfowl species. Indeed, some evidence suggests that all

the moas were extinct less than 100 years after Polynesian colonization (Holdaway

and Jacomb 2000). The demise of the moas and other birds undoubtedly was hastened

by forest clearing and other changes wrought by the Maoris, but the abundance

of moa remains at Maori village sites and the population age structure

revealed in these bones indicate that hunting was the major factor (Turvey and

Holdaway 2005).

On small islands throughout the Pacific, scores of birds are known to have become

extinct after the arrival of Polynesians (Steadman and Martin 2003). In the Hawaiian

Overexploitation 185

Figure 9.1 Many scientists believe that human overexploitation was responsible for the

extinction of many large North American mammals about 11,000 years ago. The woolly

mammoth depicted here was apparently one victim, although the caribou shown in the

background continue to survive. © American Museum of Natural History.

islands 44 species of endemic land birds out of

82 became extinct between the arrival of

Polynesians and the arrival of Europeans

(Olson and James 1984). Again, habitat

changes were undoubtedly important, but it is

likely that overhunting was a major problem,

especially for various species of flightless geese,

ibises, and rails. As we saw in Chapter 8, on

Madagascar the loss was not limited to birds.

The arrival of people led to the extinction of

two giant tortoises, a bear-size giant lemur, a

small species of hippopotamus, many other

mammals, and several elephant birds, some of

which rivaled the largest moas in size, probably

due to both overexploitation and deforestation

(Dewar 1984; Burney et al. 2004).

More recently, the history of North America

provides many striking examples of overexploitation

(Trefethen 1964; Mowat 1984;

Matthiessen 1987; Wilcove 1999). During the

colonial period beaver, turkey, and whitetailed

deer were nearly eradicated from the

coastal plain, and as the frontier moved farther

west, the wave of exploitation followed.

The arrival of railroads in the nineteenth century

provided easy access to large urban markets

for game animals harvested on the

frontier (Fig. 9.3). Market hunting led to the

demise of the passenger pigeon, arguably one

of the most abundant birds ever to have lived,

and took the American bison from extreme

abundance to extreme rarity. The heath hen,

Carolina parakeet, Labrador duck, and great

auk were hunted into extinction. Some of the great whales pursued around the world

by Yankee whalers may never recover (Kraus et al. 2005).

Note that our long history of overexploitation should never be used to justify current

overexploitation. Doing so would be akin to justifying humans killing one

another by pointing to our long history of war.

Currently, the two forms of overexploitation that receive the most attention from

conservationists are overfishing and the so-called “bushmeat” trade. Overfishing does

not attract adequate public scrutiny for many reasons including: (1) people are not

very sympathetic to fish; (2) most fishing happens at sea, beyond sight and often

beyond national boundaries; and (3) the total harvest across all fisheries has only

recently started to decline (Pauly et al. 2005). The issue of total harvest requires

closer inspection because this is a very crude measure that lumps all fish populations

or stocks together. When you examine specific fisheries (i.e. fishing for a particular

species in a particular region) you discover that 366 out of 1519 fisheries monitored

186 Part II Threats to Biodiversity

Figure 9.2 In this 1903 photo two Maori medical students

pose beside a reconstruction of a moa. (Photo from A.

Hamilton. Reproduced courtesy of the National Museum,

New Zealand.)

Overexploitation 187

by the Food and Agriculture Organization

have collapsed (Mullon et al. 2005). In particular,

the predatory fish that used to dominate

catches are being replaced by species

further down the food chain, a phenomenon

known as “fishing down the food chain,”

and this can profoundly change ecosystems

(Casey and Myers 1998; Pauly et al. 1998;

Pauly and Palomares 2005). Finally, the

total catch has been sustained by fishing in

more remote regions and at greater depths,

but we have nearly run out of new places to

exploit (Pauly et al. 2005). The history of

overfishing highlights a problem that affects

our perception of overexploitation in general:

the tendency of each generation to

think that recent population levels are normal

and to forget about past population levels.

The idea that we shift our baseline of

expectations is highlighted by a compilation

of current and historic population levels

(Jackson et al. 2001), which, for example,

shows that the roughly one million adult

green turtles that inhabit the Caribbean currently

are just a small fraction of the 16–33 million that are thought to have lived

there before European colonization.

The term “bushmeat” can be widely construed to cover any wild animal used for

human food, but in the lexicon of conservation it is used primarily when describing

the overexploitation of animals in tropical terrestrial ecosystems, especially in

forests, and especially in West and Central Africa. The range of animals involved is

enormous – from crabs to gorillas – but mammals dominate, especially rodents,

ungulates, and primates (Robinson and Bennett 2000; Cowlishaw et al. 2005; Fa

et al. 2005). Of course people have been hunting and eating wild animals in tropical

forests for millennia, but the rate of exploitation has clearly become unsustainable in

recent decades as the density of people has grown and as exploitation has been

driven by commercial enterprises rather than local, subsistence consumption. With

urban populations mushrooming and roads reaching farther and farther into formerly

remote areas the market for bushmeat is enormous, not unlike what happened

on the US frontier in the nineteenth century (Fig. 9.4). Importantly, bushmeat overexploitation

carries profound risks for people as well as wild animals; notably loss of

a supply of protein and exposure to diseases such as HIV/AIDS and Ebola. Demand

for bushmeat in West Africa has been linked to supplies of marine fish: in years when

fish supplies are strong bushmeat consumption goes down, so one solution is to

increase the supply of fish (Brashares et al. 2004). In theory, this could be done by

limiting access to the waters off West Africa, where the European Union has the

largest fishing fleet, heavily subsidized to catch fish for European consumers; in practice,

developed nations seldom curb their exploitation for the benefit of people from

developing countries.

Figure 9.3 Commercial exploitation for urban markets has

devastated populations of many species. This is a 1912 photograph

from Orange, Texas, USA; the bushmeat trade is a current

manifestation of the same phenomenon. (Photo from the

William Hornaday Collection of the US Library of Congress.)

188 Part II Threats to Biodiversity

Types of Exploitation

Commercial Exploitation

Money “makes the world go round” and is the driving force behind most exploitation

of wild life. Significant sums of money are involved because of the importance and

diversity of products obtained: food, fiber, fuel, medicine, building materials, and more

(recall Chapter 3). When we think of people who make a living selling wild life, we

often think of small, independent entrepreneurs: fur trappers, loggers, clam diggers,

and others. In practice, the scale of commercial exploitation of wild creatures ranges

from children selling berries by the roadside on a Saturday afternoon to some of the

world’s largest multinational corporations logging trees and government-owned fleets

combing the seas for fish.

Unfortunately, commercial exploitation of wild life can easily become overexploitation

for at least eight reasons.

Figure 9.4 In many tropical forests wild animals, so called “bushmeat,” are overexploited for sale in urban

markets. Logging roads provide the transportation network that facilitates this commerce. (Photo by Richard

Ruggiero, US Fish and Wildlife Service, provided by the Bushmeat Crisis Task Force.)

1 The potential market for wild products is enormous. Indeed, with a

global economy, once a wild product enters commerce, there are over six billion

potential consumers (Fitzgerald 1989; Hemley 1994). The major markets for rhino

horns and elephant ivory obtained in Africa are in the Far East; coral collected in

the Philippines is destined for Europe and North America; bear gall bladders from

the United States are extracted for Chinese markets (Table 9.1).

Overexploitation 189

Table 9.1 Some

examples of world

trade in wild life.

Primates 20,000–40,000 live

Mammal furs 15 million

Birds 1.5–4 million live

Reptiles 800,000–1,000,000 live, farmed reptiles

400,000–600,000 wild-caught, live reptiles

1–10 million skins and skin pieces

Ornamental fish 350–600 million (freshwater and marine species)

Corals 775–1100 metric tons of live and raw coral

1.5–1.6 million raw and live coral items

7500–40,000 carvings

Orchids 65,000 wild-collected orchids

917 million artificially propagated live plants

39,000 wild-collected roots

300,000 artificially propagated roots

Cacti 20,000–40,000 live plants

30,000–60,000 seeds

340,000–500,000 parts and products

The data represent a range of estimates for a portion of the wild species in trade in the 1980s and

1990s. They include both species collected in the wild (e.g. most marine fish caught for the pet

trade) and wild species propagated in captivity and then traded internationally (e.g. most freshwater

fish). Total declared value of wild products is estimated to be almost US$15 billion annually, excluding

timber and fisheries products.

Source: Broad et al. (2004) and direct communication with TRAFFIC (USA), a program of the World

Wide Fund for Nature.

2 People who exploit wild life for financial gain, like almost everyone else,

have an enormous desire for wealth. First, they need food, clothing, and shelter;

then a car, a second car, and a second home; and then status and power

become priorities. This is in sharp contrast to subsistence-based exploitation, as we

will see below.

3 Domestic substitutes for wild products are not identical and often sell for

less. People usually prefer wild berries over cultivated ones, wild (slowly grown)

wood over plantation-grown wood, venison over beef, and pheasants over chickens,

and this translates into higher prices for the wild products.

4 The market price of a wild species usually increases as it becomes rarer,

and this will precipitate greater exploitation and will make the wild species even

rarer. For example, at the end of the nineteenth century the demand for hat

feathers pushed egrets into the most remote regions of the southeastern United

States, but hunters pursued them relentlessly as the price of decorative plumes

rose to twice their weight in gold (Bent 1926). This vicious cycle is exacerbated

by the desire of people to have what their peers do not have: perhaps a shawl

woven from shahtoosh, the neck fur of Tibetan antelopes, or a Brazilian rosewood

guitar. The royalty of medieval Europe purchased unicorn horns (actually

narwhal tusks) for 20 times their weight in gold (Lopez 1986).

5 Wild resources are often communal resources, owned by no one and everyone.

This means that the costs of overexploitation are shared by many people, not

just the person who is abusing the resource, while the benefits are obtained by the

exploiter. This is what Garrett Hardin (1968) has called the “Tragedy of the

Commons.” This dilemma commonly applies to aquatic species because individuals

do not usually own the wild life of lakes and seas, whereas in terrestrial systems

landowners usually own the plants and sometimes the animals. In many countries

the major landowner is the government (national, regional, or local), and the

private individual is relatively free to overexploit. (We will return to the tragedy of

the commons in Chapter 16, “Economics.”)

6 Wild life is often found in remote places where laws and social constraints do

not operate effectively. It is much easier to use wild life irresponsibly on the high

seas or in a remote forest than under public scrutiny.

7 Commercial exploiters often have the capital to purchase expensive technology

for collecting wild life in large quantities: for example, seagoing vessels for fishing

and whaling, logging machinery, and even helicopters with which to poach

elephants and rhinos. Sometimes these are paid for by earlier profits, sometimes by

government subsidies.

8 The disparity among national currencies makes it profitable to exploit

rare species around the world. Expansion of the global marketplace through

increased transportation and lowering of trade barriers means that overexploitation

is likely to occur whenever there is a large difference in the buying power of

currencies. For example, the strength of the Japanese yen has driven the dockside

value of a single bluefin tuna to over $20,000 and that is before the costs of shipping,

handling, auctions, wholesalers, and retailers are added to what the consumer

must pay. At such high prices, most consumers would not pay for tuna, but

in Japan, where a cup of coffee can cost $15, bluefin tuna still seems reasonably

priced, and Japanese consumers eat it regularly. They thus provide an incentive for

190 Part II Threats to Biodiversity

overseas fishers to continue to pursue

bluefin tuna even when they have

become quite rare.

Subsistence Exploitation

Most rural people exploit wild life to

directly meet some portion of their personal

needs for food, clothing, fuel, and

shelter (Fig. 9.5) (Prescott-Allen and

Prescott-Allen 1982; Robinson and

Redford 1991; Robinson and Bennett

2000). Among some rural people – especially

those who are more affluent –

these activities, like a Saturday spent

fishing or gathering mushrooms, are just

supplemental to the household economy.

They are motivated primarily by recreational

needs and secondarily by subsistence

needs. At the other end of the

continuum, some rural people obtain

virtually all of their life requisites by

gathering and hunting wild species.

Worldwide, most rural people fall in the

middle of this range, obtaining a moderate

portion of their needs from the wild,

especially fuel and building materials,

and the remainder from markets and

subsistence agriculture.

In contrast to commercial exploitation,

the scale of subsistence exploitation is

limited by the number of people living in

places where they have access to wild life

and by their levels of consumption

(items 1 and 2 in the preceding section).

This is not to say that subsistence use

cannot lead to overexploitation (witness

the moas), only that it is less likely to

lead to overexploitation than commercial

use.

Recreational Exploitation

Many people routinely use wild life just for the fun of it. For example, among adults

in the United States 36% use wild animals recreationally; i.e. there are an estimated

13 million hunters, 34 million anglers, and 66 million “wildlife watchers” (people

who participate in outdoor activities that focus on viewing wild animals) (US Fish

Overexploitation 191

Figure 9.5 Subsistence use of wild plants and animals is very

important for many rural people. This boy is carrying part of a

mandrill carcass, a type of baboon that lives in the forests of West

Africa. (Photo by David Wilkie, Wildlife Conservation Society, provided

by the Bushmeat Crisis Task Force.)

and Wildlife Service 2002). When we think about recreational exploitation of wild

creatures, hunting and fishing come to mind first, perhaps because killing animals

is considered the ultimate form of exploitation. Much has been written about the

pros and cons of these sports from a conservation perspective (Mitchell 1982;

Mighetto 1991; Liddle 1997). On the one hand, sport hunters and anglers have

overexploited some populations, especially in times and places with little law

enforcement. On the other hand, in many countries sport hunters and anglers contribute

huge sums of money to conservation through license fees and taxes on their

equipment. Much of this money is used for activities, such as purchasing habitat

and hiring wardens and biologists, that benefit many species (Kallman et al. 1987),

although some of these funds are used for self-serving purposes such as stocking

streams with hatchery-reared trout. Also, funds spent by hunters and anglers for

lodging, food, and guide services can go a long way toward developing local support

for conservation in rural areas, especially in developing nations (Lewis and Alpert

1997; Harris and Pletscher 2002). As we will see in Part III, hunting has become a

necessity for controlling some populations, notably deer, in the absence of natural

predators. Incidentally, some of the worst cases of overexploitation come from

hunters who pursue smaller prey such as butterflies, mollusks, and orchids (New

1997). Naturalist collectors are notorious for going to great lengths to add rare

species to their collections.

Turning to the naturalists who simply seek contact with wild life for viewing or

photography, they too, like hunters and anglers, exploit wild creatures, although their

activities are usually called “nonconsumptive” (Edington and Edington 1986; Liddle

192 Part II Threats to Biodiversity

Figure 9.6 Even

nonconsumptive

use of wild life can

be harmful. These

tourists tromping

through a colony of

brown noddy terns

in Australia may be

causing considerable

damage.

(Photo from M.

Hunter.)

1997). Shy animals will be frightened; small plants and animals will be trampled

(Fig. 9.6). A well known anecdote among bird-watchers recounts how a large group

of birders gathered at a marsh to search for the black rail, an extremely shy bird that

is usually seen only when flushed at close quarters. The birders lined up and swept

across the marsh, but no rails were flushed. After everyone else had left, one birder

recrossed the marsh and spotted a black rail under a tuft of grass, crushed to death.

Even stony corals are vulnerable to damage by careless divers visiting coral reefs, especially

underwater photographers (Barker and Roberts 2004). Some effects may be

quite subtle; for example, just having people nearby can influence how an animal

spends its time, shifting from resting and foraging to monitoring humans (Beale and

Monaghan 2004; Mullner et al. 2004). We will return to some of the pros and cons of

ecotourism in Chapter 16, “Economics.”

Incidental Exploitation

Not all exploitation is deliberate; often in the process of

exploiting one species, other species are incidentally

exploited as well. This phenomenon is so common in

fishing that there is a specific term for this unintentional

mortality: bycatch (Lewison et al. 2004). The

best known example of this involves setting nets

around schools of tuna and drowning dolphins in the

process, a practice that has been sharply curtailed

because the popularity of dolphins led to legal actions.

Unfortunately, other forms of fishing continue to kill

many unintended victims; indeed, incidental mortality

in gill nets is the major threat to the world’s most

endangered marine cetacean, Mexico’s vaquita

(D’Agrosa et al. 2000), and some albatross species are

severely threatened by being hooked and drowned during

long-line fishing (Laich et al. 2006). In gross

terms, trawling for shrimp in tropical waters may be

the most destructive form of fishing: the total weight of

unwanted species that are dumped overboard dead

often exceeds the retained catch by tenfold (Zeller and

Pauly 2005) (Fig. 9.7). Most of these species lack the

charisma of dolphins, but because shrimp trawling

has killed many Kemp’s ridleys, a highly endangered

sea turtle, United States trawlers must now have a TED

(turtle exclusion device) to allow turtles to escape

(Lewison et al. 2003). Trawling is particularly destructive

when it scours the sea bed, obliterating the structural

diversity created by kelp, sponges, and other

species (Watling and Norse 1998; Thrush and Dayton

2002). Traps on land can also be nondiscriminating;

for example, gorillas are occasionally caught in snares

Overexploitation 193

Figure 9.7 Most of the animals killed by shrimp

trawlers are thrown overboard, and they include

endangered species such as this loggerhead turtle.

(Photo from Michael Weber, The Ocean

Conservancy.)

194 Part II Threats to Biodiversity

set to catch duikers

(small forest antelopes),

and giant pandas are

caught in musk deer

snares (Schaller 1993;

Noss 1998).

Indirect

Exploitation

The term “indirect

exploitation” could be

used to cover a wide set

of human activities that

indirectly kill other

organisms: the roads,

fences, antennas, and so

forth described in

Chapter 8; the introductions

of exotic species

that we will cover in the

next chapter. Perhaps the

clearest case of indirect

exploitation involves our

domestic animals and

their exploitation of

other species. We have

already discussed the

effects of livestock overgrazing.

Predation by

domestic animals, especially

house cats, is

another example. One

study of domestic cats

conservatively estimated that the average cat that is allowed outdoors kills about one bird

per week (Lepczyk et al. 2004); that number multiplied by 200 million cats (a conservative

guess based on an estimated 100 million in the United States alone [Clarke and Pacin

2002]) suggests that cat predation is likely to exceed ten billion birds per year globally.

Consequences of Overexploitation

The most basic consequence of overexploitation is rather obvious; if we remove too

many individuals from a population, we may subject it to all the problems of small

populations discussed in Chapter 7 (Fig. 9.8). In this section we will consider some of

the more subtle effects of overexploitation.

Figure 9.8 This graph shows how whalers have overexploited a series of great

whales, starting with fin and blue whales and then switching to sperm and sei

whales. (Redrawn by permission from Miller 1992.)

Population Effects

Not all the individuals in a population

are equally susceptible to

exploitation; their vulnerability

may be influenced by their size,

age, sex, phenotype, where they

are, and when they are there.

Consequently, the structure of a

population, particularly its age,

sex, and genetic composition, can

be changed by exploitation. Let us

briefly examine some examples.

Age

In many fisheries, the most profitable

fish to catch are the largest,

oldest individuals, but these individuals

also have the highest reproductive

capacity. Consequently, the

effects of overfishing are exacerbated

because decisions on when

and where to fish and what kind of

equipment to use (e.g. net mesh

size) are often directed toward the most fecund members of the population (Birkeland

and Dayton 2005) (Fig. 9.9). The fact that this pattern of mortality is very different

from natural mortality is especially worrying. A mismatch in age-specific mortality

between natural predators and humans can also occur in animal populations that are

subject to hunting because hunters often select animals in their prime rather than the

young or old that are easier for natural predators to kill (Solberg et al. 2000). Finally,

loggers tend to harvest trees when their growth rates are starting to decline rather

than at an age, usually much older, when natural mortality is common (Hunter

1990).

Sex

Among many mammal species, males are more exploited than females because they

are bigger and thus more desirable and because they often travel over larger areas,

making contact with people more likely. Consequently, exploited mammal populations

often have a sex ratio that is skewed toward females. The effect on population viability

may be modest because most mammals are polygynous (i.e. one male will mate with

multiple females), but there could be important exceptions. Off the west coast of

South America, preferential hunting for male sperm whales led to a shortage of males

that still persisted nearly 20 years after whaling ended. More importantly, this shortage

of males was blamed for the low pregnancy rate among females (Whitehead et al.

1997). Some population modeling has also shown that skewed sex ratios can jeopardize

a population (Ginsberg and Milner-Gulland 1994; Mysterud et al. 2002).

Overexploitation 195

Figure 9.9 Mortality resulting from human fishing tends to increase as

fish become larger (line B), whereas natural mortality is greatest when

fish are small (line A). This mismatch may exacerbate the effects of overfishing,

especially because large fish have more offspring. (Graph based

on personal communication with Robert Steneck.)

Genetic Structure

Preferential harvest can also act as a form of artificial selection and change the genetic

makeup of a population (Laikre and Ryman 1996). For example, some forests are subjected

to a form of overexploitation called high-grading in which the best trees (e.g. those

having the best form) are cut and the worst (e.g. diseased individuals) are left behind. It is

widely assumed that high-grading is likely to alter a population’s genetic structure to

some degree, but, surprisingly, this issue has received relatively little attention from forest

geneticists. One study from Ontario found a roughly 25% overall loss of alleles after harvesting

white pine, with over 80% loss among rare alleles (Buchert et al. 1997; also see

Hawley et al. 2005). Overfishing has altered the genetic structure of many salmon populations

by allowing some small males, which spend little or no time foraging at sea and

thus are less likely to be caught by commercial fishing vessels, to become a large portion

of the population (Gross 1991). These small males are able to pass on their genes by

“sneaking” access to females rather than fighting for access with the large males that

have returned from the sea. Game managers have expressed concern that the selective

nature of trophy hunting could change the genetic structure of populations (Harris et al.

2002) and at least one clear example has been documented: trophy hunting for bighorn

sheep reduced the population’s horn size and body weight of males, two traits with a

high degree of heritability (Coltman et al. 2003). Harvesting plants for medicine has led

to the artificial dwarfing of a species of snow lotus (Law and Salick 2005; Fig. 5.4).

It is not likely that a change in the age, sex, or genetic structure of a species caused by

differential exploitation could by itself cause the extinction of a species. However, it could

certainly exacerbate other factors, like small population size, and thereby make extinction

more likely. Recall from Chapter 7 that demographic stochasticity was a significant

threat to small populations and from Chapter 5 the issue of effective population size.

Ecosystem Effects

The effects of overexploitation can ripple throughout an entire ecosystem if the

exploited species has a key ecological role as a dominant species or a keystone

species. To take an extreme example, if you cut all the pines in a pine forest, you will

no longer have a forest ecosystem, at least until succession restores the forest. For a

more moderate example, consider some of the potential problems that may ensue

from partially logging a forest, such as alterations to the physical structure of the

vegetation. Notably, large trees are likely to be less common because, in a managed

forest, trees are cut when their growth rate begins to decline, and this is often long

before they reach maximum size. Similarly, trees of commercially valuable species

may become scarce in a partially logged forest. Both tree size and species are important

habitat attributes for many animals, ranging from an eagle seeking a suitable

nest site to a bark beetle looking for a spot to carve its tunnel. Another problem can

arise because dead or dying trees are often uncommon in managed forests where

trees are usually cut before they are too susceptible to disease. This may create a

shortage of habitat for a huge number of invertebrates, fungi, and microorganisms

that use the dead wood of snags and logs; woodpeckers and other cavity-nesting vertebrates

that we commonly associate with snags are just the tip of the iceberg

(McComb and Lindenmayer 1999).

196 Part II Threats to Biodiversity

This is a very incomplete list of the potential consequences of timber harvesting (for

a fuller treatment of these issues, see Hunter 1990, 1999). The bottom line is that we

cannot remove a substantial portion of the population of a dominant species without

affecting the rest of the ecosystem to some degree. Although we have focused on

forests here, this principle will apply to any ecosystem, such as overexploiting the

grass in a grassland ecosystem through excessive livestock grazing, or overfishing the

fish in an aquatic ecosystem.

Overexploiting a species that is relatively uncommon, but has a keystone role, will

also have profound effects upon the rest of the ecosystem (Soule et al. 2003, 2005).

For example, sea otter populations were overtrapped along several stretches of the

Pacific coast, and this allowed populations of their prey, notably sea urchins, to flourish

(Duggins 1980). The abundance of sea urchins limited recruitment of kelp, and as a

result entire kelp bed ecosystems, with a large set of dependent species, disappeared.

Another layer of complexity has been added to this “trophic cascade” story in parts of

Alaska where killer whale predation on sea otter populations has also allowed kelp

forests to develop (Estes et al. 1998). It is likely that killer whales switched their attention

to sea otters because their traditional prey, large whales, were less available

because of overexploitation by humans (Williams et al. 2004). A similar example

comes from many coral reefs where overfishing of herbivorous fish has left populations

too small to control algae that are blanketing the coral reef and outcompeting coral

(Hawkins and Roberts 2004). Turning to terrestrial ecosystems, Flannery (1995) has

advanced a controversial idea that human extirpation of large herbivores (marsupials

the size of a rhinoceros) roughly 50,000 years ago increased the vegetation biomass

and thus provided more fuel for the fires that have shaped so much of Australian ecology

ever since. In western North America, local extirpation of an important terrestrial

predator, gray wolves, resulted in an overabundance of elk and various indirect effects:

excessive browsing on aspen and willow, which meant less food for beavers, which in

turn meant less habitat for riparian birds (Hebblewhite et al. 2005).

We must be particularly vigilant to recognize the loss of keystone species in ecosystems

that superficially appear to be intact. In a provocative paper, “The Empty Forest,”

Kent Redford (1992) writes about the vast stretches of Amazonian forest that seem to

be undisturbed, but that are almost devoid of large mammals and birds because of

overhunting (Fig. 9.10). He speculates about what this may mean in the long term

because of the ecological roles of these species as seed dispersers, herbivores, and so

on. Similarly, while conservation biologists often focus on avoiding the extinction of a

species, we must recognize that the ecological role of species can be compromised

whenever their populations are too low; in other words, they may become extinct

with respect to their ecological function long before they totally disappear (Soule et al.

2003, 2005; Sekercioglu et al. 2004).

Some Final Perspectives on Exploitation

It is easy to condemn the overexploitation of wild life, and conservationists should do

so with vigor and conviction, but we must be careful to focus on overexploitation and

not exploitation per se, for as consumers of wild life we all exploit wild life. To take a

particularly relevant example, the vast bulk of trees harvested in the world come from

seminatural forest ecosystems, not plantations, and that is generally good; it means

Overexploitation 197

more habitat for wild life. However, it also means that by reading this book you are

probably exploiting wild trees. In other words, we have to be responsible consumers,

not just critics of the people who make their living from the use of wild life. When told

that in some countries elephant poachers are shot on sight without the due process of

law, many people nod in agreement about an unfortunate but justifiable policy. These

same people would be shocked at the suggestion that customs officials should shoot

tourists returning from abroad with ivory souvenirs (Fig. 9.11). The unthinking role of

consumers in overexploitation is captured nicely in a quote from the actress Gina

Lollobrigida, shortly after she purchased seven new fur coats: “What can I do? The tigers

in my coat were already dead. ... If I don’t buy the coats, somebody else will.” Is ignorance

an excuse for such behavior?

In particular, biologists who condemn overexploitation should not forget that their

profession has many skeletons in the closet (literally and figuratively) from past activities.

For example, beginning in 1884 several museum-organized expeditions sought to

find the last northern elephant seals without success; finally, in 1892 they found

seven and collected six of them (Busch 1985). Fortunately, some seals were apparently

overlooked, and the species has recovered.

It is also important to remember that killing plants and animals is not the only way to

exploit them. The market for pets is enormous, and millions of live animals, especially

fish, birds, and reptiles, are caught in the wild and sold every year (Tissot and Hallacher

2003; Schlaepfer et al. 2005). Live plants, particularly orchids and cacti, are also in great

demand. Obviously, from the perspective of a wild population it does not matter whether

198 Part II Threats to Biodiversity

Figure 9.10 Hunting pressure shifts the community structure toward smaller species of

game vertebrates, based on research at 25 Amazonian forest sites. These are scatterplots

of the relationship between level of hunting pressure (N, none; L, light; M, moderate; H,

heavy) and the percentage contribution of species within three size classes to the overall

density and biomass. Spearman correlation coefficients (rs) indicate statistical significance.

(From Peres 2000.)

Overexploitation 199

CASE STUDY

The Gulf of Maine

Robert S. Steneck1

Sailing across the Gulf of Maine today you can see a vast ecosystem that appears little changed after thousands of

years of human use. However, this illusion would soon disappear if you could slip beneath the surface and see the gulf

through the eyes of a marine creature. Both coastal and offshore marine communities of the Gulf of Maine have been

changed profoundly over the past several hundred years because of the virtual elimination of large predatory fish.

As long as 8000 years ago, the “Red Paint People” lived year-round on the coast of Maine catching marine fish

no more than a short canoe trip from shore (Bourque 2001). The refuse or “middens” left by these and subsequent

indigenous people accumulated over thousands of years, and by studying them, archeologists learned that these

people subsisted on large fish such as the Atlantic cod. Over the next several thousand years large fish, such as

Atlantic cod averaging a meter in length (Jackson et al 2001), with some growing to nearly 100 kilograms in mass

(Collette and Klein-MacPhee 2002), remained sufficiently abundant to constitute over 80% of the bone volume of

an individual is dead or alive when it is

removed. Indeed, the trade in live organisms

can be more deleterious because many individuals

die between the time of capture and

the time they arrive at their ultimate destination,

and thus a larger number needs to be

acquired initially. Some of the worst examples

of this involve young primates, in great

demand for medical research, that are often

captured by shooting their mothers from the

treetops. Of course, many of us are alive

today because of medical research, and so,

again, we should condemn such practices,

but must tread carefully to avoid hypocrisy.

The key solution to these dilemmas revolves

around careful management of exploited

populations, an issue that we will cover in

Chapter 13, “Managing Populations.”

Finally, we should not lose sight of the fact

that the loss of ecosystems is typically a much

more important threat to biodiversity than

overexploitation. It is generally far better to

have a forest in which some of the large animals are overexploited than to convert the

forest into a pasture for raising cattle. This chapter has focused on the numerous examples

of overexploitation, but the general truth of the following remains:

The law doth punish man or woman,

That steals the goose from off the common,

But lets the greater felon loose,

That steals the common from the goose.

Anonymous 1764

Figure 9.11 Consumers provide the market for wild life trade

items and thus are at least half the problem, despite government

agents who attempt to stop illegal wild life trade. (Photo from

John and Karen Hollingsworth, US Fish and Wildlife Service.)

200 Part II Threats to Biodiversity

the middens (Steneck and Carlton 2001). When the first Europeans explored the Gulf of Maine, it was the abundance

of large fish that so impressed them (Caldwell 1981). The northern half of Juan Vespucci’s 1526 map of the

New World was identified as Bacallaos, which is Portuguese for “land of the codfish.” In 1602, Bartholomew

Gosnold named Cape Cod for the myriad of fish that “vexed” his ship. Captain John Smith reported three important

facts in 1616: (1) that cod were abundant along the coast; (2) that native Americans already knew this; and

(3) that the cod in Maine were two to three times larger than those found elsewhere in the New World. In the early

1600s, seafood from the Gulf of Maine had a larger share of the market in Europe than it does today. At that time,

10,000 men were employed fishing for cod in New England (Caldwell 1981); by the 1880s, three times that number

were employed in Nova Scotia alone (Barnard 1986). Late

nineteenth-century advances in ships and fishing technology

greatly increased fishing effectiveness. This may have

been the zenith of the codfish industry.

Since the nineteenth century, cod and other large-bodied

predatory fish have declined in abundance and size until

they have become virtually absent from coastal habitats

(Witman and Sebens 1992; Steneck 1997; Steneck and

Carlton 2001; Lotze and Milewski 2004; Steneck et al.

2004). This decline is evident in published charts of coastal

fishing grounds. The continuous near-shore fishing grounds

charted in the nineteenth century were reduced to small

discrete patches by the 1920s (Rich 1930) and today are

gone. In addition to declining abundances, average fish

body size has steadily dropped over the past several decades.

For example, codfish sizes decreased from an average of

about 80 cm in 1950 (Bigelow and Schroeder 1953) to 30

cm in the late 1980s (Ojeda and Dearborn 1989).

There is growing evidence that coastal marine landscapes

have changed as a result of the loss of the large

predatory finfish (Fig. 9.12). Today, mobile benthic invertebrates

(e.g. Menge and Sutherland 1987) and small, commercially

unimportant finfish (Wahle and Steneck 1992;

Steneck 1997) are highly conspicuous and appear to be the

most important predators in coastal zones of the Gulf of

Maine. Experiments indicate that adult crab, lobsters, and

sea urchins live today in coastal habitats without significant

threats from predators (Wahle and Steneck 1992; Steneck

1997, 1998; Steneck and Sala 2005). Furthermore, the

absence of predators allows more lobsters to live in areas

with little shelter than was possible when predators were

abundant. This expansion of habitable areas for lobsters

may have contributed to the currently thriving lobster

industry, which in recent years has repeatedly exceeded its

record harvest set in the 1880s (Steneck and Wilson 2001;

Steneck 2006).

The hyperabundance of sea urchins was also probably

the result of populations growing unchecked by predators

Figure 9.12 The decline of large, predatory fish

in the Gulf of Maine (e.g. codfish that are large

enough to prey on adult lobsters) has dramatically

affected the entire marine community.

(Photo taken on Monhegan Island; from Edward

W. Coffin.)

Overexploitation 201

(Steneck 1998). At high densities their grazing denudes coastal zones of most erect, fleshy seaweeds such as kelp

(Steneck et al 2002) and thus reduces coastal productivity and habitat structure for other organisms (Bologna and

Steneck 1993). However, in the late 1980s sea urchins themselves became targeted for their roe, which is highly valued

in Japan. In a shockingly short period – about a decade – the carpets of sea urchins disappeared (Andrew et al. 2002).

Since sea urchins are the dominant herbivore in the system, the reduced grazing resulted in the establishment of kelp

forests and shag-carpet tangles of red algae (Steneck and Carlton 2001).

What we have observed in the Gulf of Maine is called “fishing down the food web” (Pauly et al. 1998). That is,

top predators such as cod are often the first fish targeted because they are highly valued for food and commerce. As

that trophic level declines, its prey become more abundant and become the new target for fisheries. If the prey species

are themselves strong interactors, then their prey, at yet lower trophic levels, are also released from predator control.

In many relatively undisturbed marine ecosystems, consumer effects translate beyond the next lower trophic

level; these are called “trophic cascades.” They occur when carnivores reduce herbivore abundance, allowing plants

(or algae) to grow uncropped. By definition, trophic cascades cause demographic effects at least two trophic levels

below apex predators. Studies have shown that coastal marine communities have particularly strong predator-toproducer

trophic cascades (Shurin et al 2002).

Overfishing in the Gulf of Maine has sequentially disrupted the functioning of its coastal trophic cascade, starting

with the top predators, such as cod (Steneck 1998). Fishing in the Gulf of Maine does not threaten the harvested

organisms with biological extinction, but if their population densities fall low enough, they lose their ecological function

(called “trophic level dysfunction,” sensu Steneck et al 2004). As a result, the next lower trophic level becomes

both abundant and the new fisheries target (Steneck 1997; Lotze and Milewski 2004; Steneck et al. 2004). Such

fishing down of food webs continues to this day, with many new fisheries emerging for distant global markets.

Recently, a variety of intertidal and subtidal seaweeds have been harvested for food and fertilizer, and a market

for small, herbivorous, periwinkle snails has developed (Fig. 9.13). Temporal trends in fishing down foodwebs can be

seen via fractional trophic-level analysis (Pauly et al. 2001), in which each harvested species is characterized by its

trophic level grading, from 1 for primary producers (algae) and 2 for herbivores up to 4 or higher for apex predators

(with the great white shark’s fractional trophic level being highest at 4.6). The trophic level of each species is

weighted by its abundance in landings (Fig. 9.13). From this analysis we see that people consumed higher order carnivores

for thousands of years until relatively recently (Fig. 9.13a). However, in the past several decades since predator

extirpation, the harvested trophic levels have plunged (Fig. 9.13b). The rate of change fuels the growing

concern that sea urchins, snails, and seaweeds may be incapable of sustaining the escalating pressures on them. It

appears that the Gulf of Maine is experiencing accelerating trophic level dysfunction (Steneck et al. 2004).

The Gulf of Maine may be particularly vulnerable to trophic level dysfunction because its species diversity is

naturally so low (Witman et al. 2004). The low diversity is the result of the North Atlantic being the youngest of

the world’s oceans and the most battered by almost complete coastal glaciation every 20,000 years or so. Thus

there are very few endemic species. Most of those present came from the North Pacific initially and from Europe and

the eastern North Atlantic since New England’s last glaciation 18,000 years ago. The few hardy species that persist

create more of a food chain than the more common food web with multiple species at each trophic level. Thus,

when species richness is high, overfishing of one species may be compensated for by another functionally equivalent

one in that trophic level. However, the Gulf of Maine does not have other taxa in some trophic levels. For example,

the green sea urchin is the only important herbivore in the western North Atlantic (Steneck et al. 2002).

Consequently, when the sea urchin fishery began in the late 1980s, the target was not just a herbivore, it was effectively

the entire trophic level. In less than a decade, sea urchins have been extirpated over vast areas of the Gulf of

Maine, causing the entire community of hundreds of species (most of them noncommercial) to be profoundly

altered (Steneck et al. 2002). Some of these changes were predictable, such as the increase in kelp and other algae

resulting from the loss of herbivory. Other changes are entirely unpredictable. For example, after the seaweed community

changed, the habitat architecture also changed. What was once a featureless, encrusting, calcareous,

202 Part II Threats to Biodiversity

algal-dominated bottom became a

shag-carpet of red algae. This is

an ideal habitat for settling crabs

that would have been eaten by everpresent

small fish without the algae

in which to hide. However, swarms of

baby crabs live in the algal shag carpet,

and they consume virtually all

of the settling urchin larvae. So,

despite there no longer being any

harvesting of sea urchins (because

there is nothing to harvest), the population

has not returned – it is locked

in an alternate, algae-dominated,

stable state.

Fishing down food webs in the

Gulf of Maine has resulted in hundreds

of kilometers of coast now

having dangerously low biological

and economic diversity. The trophic

level dysfunction of both apex predators

and herbivores leaves a coastal

zone suited for crabs and especially

lobsters – the latter attaining staggering

population densities, exceeding

one per square meter along

much of the coast of Maine (Steneck

and Wilson 2001). While the economic

value of lobsters is high, this

one species accounted for over 80% of

the total value of Maine’s fisheries in

2004. The remaining 42 harvested

species account for the remaining

20% of the value. Thus, if a disease

such as the one that decimated Rhode

Island’s lobster stocks infects lobsters in the Gulf of Maine, the result will be socio-economic disaster. The fishing

community has no other economically viable species to fish.

This and other examples worldwide of fishing down marine food webs (e.g. Pauly et al. 1998) indicate that overexploitation

is occurring at a very large scale and its impacts are escalating at an alarming rate. Whereas prehistoric

indigenous Americans may have had thousands of years of sustainable harvests, we currently seem unable to

have sustainable harvests and relatively stable marine communities for more than a few decades or even a few years

(Fig. 9.13). The accelerating booms and busts – some of which become locked into unfavorable alternate stable

states – are the antithesis of the tranquil stability we usually associate with our vast oceans.

Figure 9.13 Temporal trends in fractional trophic levels of harvested

species over the past 43,000 years. (a) Entire record of trophic level (TL)

analysis from archeological studies to the past three decades (in rectangle

at far right of the trend line). (b) Expanded trend in fractional trophic levels

since 1970. (Modified from Steneck et al 2004.)

1 School of Marine Sciences, University of Maine, Darling Marine Center, Walpole, Maine.

Overexploitation 203

Summary

Exploitation of wild plants and animals is a fundamental human activity, although when it

involves killing sentient species, especially birds and mammals, some people are uncomfortable

with the idea. When exploitation becomes overexploitation (i.e. when our use of a population

seriously threatens its viability or radically alters the natural community in which it lives),

everyone should be uncomfortable with the idea, even those who readily accept the idea of

killing other organisms. Human overexploitation has a long history, especially on islands, but

that is no excuse for the abuses that persist today. The worst of these involve commercial

exploitation, particularly because the market demand for wild organisms is enormous and the

rarer a species becomes the more it is worth. Subsistence use of wild organisms is limited by the

number of people living in rural areas and their needs, but still has the potential to threaten

populations. Overexploitation can also result from incidental exploitation (catching species

accidentally while harvesting other target species) and recreational exploitation (e.g. hunting,

fishing, and, under some circumstances, nonconsumptive activities such as bird-watching).

Besides reducing population size, overexploitation can have deleterious effects on the age, sex,

and genetic structure of populations, and, when directed against keystone or dominant species,

it can negatively affect whole ecosystems. Finally, when condemning overexploitation, it is

important to think about the consumers of wild species – all of us – as well as those who earn

their living harvesting wild life.

FURTHER READING

For further information on prehistoric overexploitation see Martin and Klein (1984), Flannery (1995, 2001),

and MacPhee (1999). For the historic period Mowat (1984), Matthiessen (1987), and Wilcove (1999) are interesting

reading. Liddle (1997) and Oldfield (2004) provide accounts of the impacts of recreational exploitation

and global trade, respectively. Safina (1998) offers a particularly compelling account of overexploitation in the

sea. Check out the websites of Traffic, a group that monitors wild life trade (www.traffic.org) and the Bushmeat

Crisis Taskforce, a group focused on commercial exploitation of wild animals for meat (www.bushmeat.org).

Many conservation groups are concerned with overfishing; it is a major issue for the Ocean Conservancy

(www.oceanconservancy.org).

204 Part II Threats to Biodiversity

TOPICS FOR DISCUSSION

1 Assuming that exploitation can be carefully controlled, should commercial exploiters of wild life (people doing

it to make a living) have precedence over recreational exploiters of wild life (people doing it for fun)? Why or why

not?

2 Imagine that you wished to obtain a large snake for an environmental education center where people would

learn to see snakes in a positive light. Would you rather buy the snake from people who breed them in captivity

or from people who collect them at a sustainable rate from a large forest that they own? Why?

3 One can blame commercial overexploitation on both the people who directly do the exploiting and those who

buy the products, but which group deserves more of the blame? Does this change depending on the economic

status of the people?

4 Many laws have been passed to regulate overexploitation. Try to think of some practices that might minimize the

effects of overexploitation on the age, sex, and genetic structure of populations, as well as the effects of overexploitation

on entire ecosystems.

5 What steps can consumers of wild life take to make sure their consumption is not contributing to overexploitation?

e eBook Collection chapter 11

Maintaining

Biodiversity

Unless another large meteorite slams into the earth between the time these words are written

and when you read them, it is reasonable to trace most threats to the earth’s biodiversity back to

human causes. Because of this, some people feel that the best way to diminish our effect on biodiversity

is to leave it alone. In other words, we could simply arrest our population growth,

reduce our use of resources, and withdraw from large stretches of the planet, leaving the other

biota to operate without us. This would substantially diminish the overall threat to biodiversity,

but it is not realistic. In practice, we need to work with existing social, political, and economic

systems, trying to change them from within to make them more compatible with existence of all

life on earth (the subject of the book’s last section, Part IV). Societies can be changed over

decades or centuries; unfortunately, this is not fast enough. We must also attack the problem of

maintaining biodiversity directly and quickly because species are being lost now. In Part III we

will examine the things that can be done on the ground, in the field, out in the wild places, to

maintain biodiversity by protecting and managing ecosystems (Chapters 11 and 12) and populations

(Chapter 13). In Chapter 14 we will discuss the role zoos, aquaria, and botanical gardens

can play in maintaining biodiversity, especially their role as insurance against the possibility that

our efforts in the field may not succeed.

PART III

Photo opposite: Flower Mirror © Marc Adamas

CHAPTER 11

Protecting Ecosystems

Conservation biologists are fairly skilled at looking at the big picture, at seeing forests,

not just trees. They understand that we cannot maintain genetic diversity without

maintaining species diversity and that we cannot maintain species diversity without

maintaining ecosystem diversity. They know that we cannot think about a species in

isolation; we have to be concerned about the whole suite of interacting species and

environmental features that constitute its habitat. As Shakespeare’s Shylock, the merchant

of Venice, said “You take my life when you take the means whereby I live.”

When biodiversity advocates think about ecosystem conservation, they usually

think first about reserves. In particular, they are likely to focus on protecting a cluster

of ecosystems that are representative of the region’s ecological diversity and thus are

likely to contain a large portion of a region’s species. This is the coarse-filter strategy

of maintaining biodiversity (recall Fig. 4.6). In this chapter, we will consider the

strategies conservationists employ to protect natural ecosystems (i.e. ecosystems that

are little changed by people) by establishing and managing reserves.

Most conservationists also recognize that protecting some exemplary natural

ecosystems is not enough. We must look beyond the boundaries of reserves to the

ecosystems that form the larger matrix in which reserves are imbedded, especially

those seminatural ecosystems in which we can integrate management for biodiversity

and management for commodities such as timber, livestock, and fisheries. In

most parts of the world, seminatural, cultivated, and urban ecosystems cover a far

greater area than protected ecosystems and their management will be covered in

Chapter 12, “Managing Ecosystems.” The idea that some places should be protected

from the usual gamut of human uses goes back at least 3000 years to Ikhnaton,

king of Egypt, and probably earlier to sacred mountains and groves unrecorded by

history (Fig. 1.2; Alison 1981). It is hard to know why such places were selected for

protection and exactly what types of protection were enacted. In this chapter we will

consider three contemporary issues regarding protecting ecosystems: selecting particular

ecosystems to be protected; designing a reserve for those ecosystems; and

managing a reserve after it is established. Natural places protected from most human

activities may have many names: parks, refuges, sanctuaries, wilderness areas, preserves,

and more (Table 11.1). Sometimes, these different names reflect different

management goals and strategies, and, sometimes, they simply reflect the ambiguity

of language. We will use “reserve” as a generic term for areas in which natural

ecosystems are protected from most forms of human use; “protected area” is another

common generic term.

Table 11.1 The

United Nations

recognizes seven

basic categories of

protected areas.

Category Ia Strict nature reserve: protected area managed mainly for science.

(4731 units covering 1,033,888 km2)

Definition: Area of land and/or sea possessing some outstanding or

representative ecosystems, geological or physiological features and/or

species, available primarily for scientific research and/or environmental

monitoring.

Category Ib Wilderness area: protected area managed mainly for wilderness

protection. (1302 units covering 1,015,512 km2)

Definition: Large area of unmodified or slightly modified land, and/or sea,

retaining its natural character and influence, without permanent or

significant habitation, which is protected and managed so as to preserve

its natural condition.

Category II National park: protected area managed mainly for ecosystem

protection and recreation (3881 units covering 4,413,142 km2)

Definition: Natural area of land and/or sea, designated to:

(a) protect the ecological integrity of one or more ecosystems for present

and future generations; (b) exclude exploitation or occupation inimical to

the purposes of designation of the area; and (c) provide a foundation for

spiritual, scientific, education, recreational, and visitor opportunities, all of

which must be environmentally and culturally compatible.

Category III Natural monument: protected area managed mainly for conservation

of specific natural features (19,833 units covering 275,432 km2)

Definition: Area containing one, or more, specific natural or natural/cultural

feature that is of outstanding or unique value because of its inherent

rarity, representative or aesthetic qualities, or cultural significance.

Category IV Habitat/species management area: protected area managed mainly for

conservation through management intervention (27,641 units covering

3,022,515 km2)

Definition: Area of land and/or sea subject to active intervention for

management purposes so as to ensure the maintenance of habitats

and/or to meet the requirements of specific species.

Category V Protected landscape/seascape: protected area managed mainly for

landscape/seascape conservation and recreation (6555 units covering

1,056,008 km2)

Definition: Area of land, with coast and sea as appropriate, where the

interaction of people and nature over time has produced an area of

distinct character with significant aesthetic, ecological, and/or cultural

value, and often with high biological diversity. Safeguarding the integrity

of this traditional interaction is vital to the protection, maintenance, and

evolution of such an area.

Category VI Managed resource protected area: protected area managed mainly for the

sustainable use of natural ecosystems (4123 units covering 4,377,091 km2)

Definition: Area containing predominantly unmodified natural

systems, managed to ensure long-term protection and maintenance of

biological diversity, while providing at the same time a sustainable flow of

natural products and services to meet community needs.

Categories I to III are clearly reserves as we are using the term here. The 2003 United Nations estimates

of the number of each different type of protected area and their total area appear in parentheses;

34,036 additional sites totaling 3,569,820 km2 were not assigned to any category. The data

generally apply only to areas protected by national governments, not areas protected by states,

provinces, counties, private organizations, and so on.

Reserve Selection

Traditionally, the selection of reserves has been driven by aesthetics and recreation

because people love to visit spectacular places: lakes ringed by forested slopes, snowcovered

crags, wind-swept beaches. Some places were protected because they harbor

an unusual diversity and abundance of wild life (e.g. the Serengeti plains of

Tanzania and Kenya) or a species that is uncommon and spectacular (e.g. the redwoods

and sequoias of California). Some reserves even focus on species that are

uncommon but not very spectacular. For example, in the United Kingdom many

reserves are managed for natterjack toads, which look a bit too much like a lump of

mud to appear on the cover of a travel magazine (Phillips et al. 2002), as well as the

improbably named wart-biter, a rare species of bush cricket. We will discuss managing

the habitat of single species in Chapter 13, “Managing Populations.” Here the

primary focus will be on protecting ecosystems as a strategy for maintaining multiple

species, while acknowledging that it is also important to think about maintaining

ecological and evolutionary processes, especially in the long term (Cowling and

Pressey 2001).

All reserves – even those selected for their scenic qualities – encompass ecosystems

or portions of ecosystems and thus maintain habitat for a variety of species.

However, natural resource managers cannot be content with a haphazard approach

because it will lead to an incomplete array of protected ecosystems that provide little

or no habitat for many species. Yet how can we systematically protect the habitat of

most species if relatively few species have been described by scientists to date

(Chapter 3), and if, even in relatively well studied regions such as Europe, we know

little about the distribution of most known species? Obviously, one strategy is to do

the best we can with whatever species distribution data are available (Margules and

Pressey 2000; Gaston and Rodrigues 2003; Brooks et al. 2004c, d). An important

complement to this strategy, or even alternative, lies with the coarse-filter approach

to maintaining biological diversity (Chapter 4) and its assumption that most species,

known and unknown, will be protected if a reserve system contains a complete array

of the region’s ecosystems. We will describe the species-based approach first, then

turn to ecosystems.

Centers of Species Diversity

The world’s species are not distributed uniformly. There are some obvious “hotspots”

such as tropical forests and coral reefs that have unusually large numbers of species

(Fig. 11.1a). Other places can be called hotspots because they have a wealth of

endemic species: Madagascar, the Cape region of South Africa, and southwestern

Australia are good examples (Fig. 11.1b). Not surprisingly, many conservationists

believe that these places with high species richness or lots of endemics should be a

major priority for establishing reserves (Myers 1990; Myers et al. 2000b; Mittermeier

et al. 2004), especially in regions that are experiencing severe rates of ecosystem loss

(Fig. 11.2).

Taxonomists can provide a general sense of where centers of diversity and

endemism might exist, but to explore the issue systematically requires a geographic

information system (GIS) that can assimilate many layers of information into

228 Part III Maintaining Biodiversity

Figure 11.1 These maps depict global patterns of reptile distributions based on the terrestrial ecoregions shown

in Fig. 4.3. (a) The relative species richness of reptiles in different ecoregions. (b) The ecoregions that have the

most species that are endemic to a given ecoregion. (Maps reproduced with permission from the World Wide

Fund for Nature; see worldwildlife.org/wildfinder/printableMaps.cfm for maps for birds, reptiles, and amphibians.)

230 Part III Maintaining Biodiversity

Figure 11.2 The idea of focusing conservation in areas with high species richness and endemism and high

degrees of threat has led Conservation International to propose a set of global hotspots for conservation action.

Different colors are used to distinguish adjacent hotspots. (Map reproduced with permission from Conservation

International; see Mittermeier et al. 2004.)

composite maps (Figs 11.1, 11.3) (Scott et al. 1993; Groves et al. 2002; Groves

2003). GIS, remote sensing, and related technologies open the door to various

quantitative techniques for selecting reserves, notably computer models that can identify

a set of reserves that complement one another. In other words, a particular

group of reserves can be chosen to limit overlap in the species they hold, thereby

potentially conserving the smallest area necessary to “capture” all species at the

lowest cost (Williams et al. 1996; Margules and Pressey 2000; Drechsler 2005).

To illustrate complementarity, imagine four potential reserves: Site A has red, green,

and blue snails; Site B has red, green, and yellow snails; Site C has yellow, orange,

and purple snails; Site D has red and orange snails. Selection of which two sites

maximizes “complementarity”? Choosing Sites A and C would, because they share

no snail species and contain all six species. Any other combination is less efficient

at capturing the snail diversity present. Also note that both Sites A and C are irreplaceable

because they have species that are unique in this set (blue and purple

snails, respectively). Irreplaceability will make a potential reserve much more

important.

Extensive use of GIS has revealed some weaknesses in the hotspot concept. For

example, a study of global bird distributions found relatively little overlap between

Protecting Ecosystems 231

hotspots of species richness,

threatened species, and

endemism (defined here as birds

with relatively small geographic

ranges) (Orme et al. 2005), and

a regional study of plants found

a similar result (Stohlgren et al.

2005). More problematically,

hotspots of species richness for

different taxonomic groups (e.g.

butterflies versus birds) often do

not coincide (Prendergast et al.

1993; Gaston 2000; Oertli et al.

2005), thus suggesting that a few

well known taxa are not good surrogates

for biodiversity writ large.

On the other hand, at least one

study found that patterns of

species composition are similar for

different taxonomic groups (Su

et al. 2004) (e.g. both the butterflies

and birds of Site A are different

from Site B as measured by

species composition). It seems

likely that species composition

reflects ecological differences

better than species richness

patterns.

Ecosystems and

Environmental

Surrogates

Reserve selection is often driven

by the distribution of ecosystems,

either because they are conservation targets themselves or because they are a way

to organize species conservation based on the coarse-filter concept that assumes

that protecting a complete set of all ecosystems will protect most – but not all –

species (Chapter 4).

An effective coarse-filter approach requires a detailed ecosystem classification system.

It is not sufficient simply to define a “forest ecosystem” or a “lake ecosystem”

because, for example, the biota of a warm-water, acidic lake would show little overlap

with that of a nearby cold-water, alkaline lake. For this purpose an ecosystem classification

system should be based on both the physical environment (e.g. water, soil, and

climate factors) and the species that dominate the ecosystems. In practice, classifications,

particularly of terrestrial ecosystems, are usually weighted toward dominant

Figure 11.3 Conservation biologists have used geographic

information systems (GIS) to combine maps representing distributions

of many different species and existing reserves (layers of information)

into composite maps. In this simple figure (redrawn by permission

from Scott et al. 1993), a composite map based on the ranges of just

three species of Hawaiian finch shows that the existing reserves did

not coincide well with the areas of finch diversity. See Scott et al. (1993)

for a description of these techniques. See Fig. 11.1 for more complex

examples.

species (e.g. oak–pine forests, spruce–fir forests) because it is often easier to recognize

the distribution of conspicuous species than the distribution of physical features.

There are two problems with relying primarily on dominant species; first, dominant

species are often successful species that are able to thrive in a variety of environments,

and thus their distribution may mask factors that shape the distribution of other

species. Second, many species are continuously changing their range in response to

climate change (Chapter 6). Consequently, it is better to focus the coarse-filter strategy

on the physical environment as the arena that holds biological diversity, rather than

on the dominant species that happen to occupy the arena at this time (Hunter et al.

1988).

Some researchers have used environmental factors directly, without classifying

ecosystems, to predict the distribution of species as a basis for selecting reserves (Faith

et al. 2004; Sarkar et al. 2005). For example, Trakhtenbrot and Kadmon (2005) used

maps of rainfall, temperature, and bedrock geology in Israel to identify a set of sites

that would be complementary (i.e. represent a range of environments with little overlap)

and then showed that these sites did a good job of representing the distribution of

plant species, including rare species.

Classification of ecoregions (Fig. 4.3) also plays a role in reserve selection.

First, ecoregions are a logical basis for delineating the areas within which we will

try to maintain a representative array of ecosystems (Groves et al. 2002; Groves

2003), although inevitably politically defined regions are often used too.

Ecoregions are also used by global organizations to decide where they should

focus their efforts to establish reserves (Olson and Dinerstein 1998; Hoekstra et al.

2005).

There is a fair amount of disagreement between advocates of a strongly speciescentered

approach and those who believe that we should start with ecosystems and

environmental factors and then turn to species to fill in the holes (i.e. a coarse filter

leading to fine filters) (see Brooks et al. 2004c, d, and responses such as Pressey 2004).

The arguments primarily revolve around logistical issues – notably, which data sets are

most readily available and which do the best job of predicting the distribution of overall

biodiversity – and thus for now the answer seems to be to use a variety of data, both

biotic and physical (Bonn and Gaston 2005).

Filling the Gaps

Conservationists rarely have the opportunity to create a system of reserves from

scratch. Usually there is an existing set of reserves and they must undertake a

process called “gap analysis” to identify holes in the existing network, which is

often unbalanced and incomplete from the perspective of biodiversity conservation

(Fig. 11.3; Scott et al. 1993; Pressey 1994; Jennings 2000; Groves 2003). In particular,

high-altitude ecosystems sometimes dominate reserve systems because they

are appreciated for their scenery and are of marginal value for most economic

endeavors. In contrast, areas with fertile soils and benign climates are often

uncommon in reserve systems because they are in demand for agriculture; indeed

most such areas were already converted to agriculture before people began creating

substantial reserve systems (Hunter and Yonzon 1993; Scott et al. 2001;

Fig. 11.4). Marine ecosystems have long been very poorly represented in reserve

232 Part III Maintaining Biodiversity

Protecting Ecosystems 233

Figure 11.4 In Nepal there are few protected areas at middle elevations because, historically,

most of the people lived in these areas. High altitude areas are represented in

reserves because they are scenic and have few people; the reserves in low-lying areas are

a legacy of the past when malaria limited human populations. Many species are found

exclusively in the ecosystems characteristic of the middle altitudes, and thus this is an

important gap in the network of existing reserves.

systems despite their aesthetic, recreational, and ecological values, although this is

finally starting to change with the creation of what are often called “marine protected

areas” (MPAs) (see Lubchenco et al. 2003 and 16 associated papers). This

deficiency can generally be traced to our lack of sensitivity to things that happen

underwater.

How Many to Select

Nature reserves are very popular with the public although not necessarily with

those who depend on large areas of land or water for their livelihood.

Consequently, the issue of how much area needs to be protected is frequently

debated. Clearly, one small representative of each type of ecosystem in each region

is not sufficient because it would be too small to protect viable populations of many

species, especially animals with large home ranges, and it would be vulnerable to a

catastrophic disturbance. Unfortunately, there may be a considerable gulf between

what is ecologically desirable and politically feasible. The World Conservation

Union has long recommended that at least 10–15% of the total area of each

ecosystem type be protected and the Convention on Biological Diversity has set a

goal of protecting at least 10% of each ecoregion by the year 2010 (Chape et al.

2005). Currently the global coverage of protected areas is estimated to be about

12% of the land surface but the distribution is very imbalanced among ecosystem

types. For example, there are sizable areas of temperate coniferous forest and tundra

protected, while many other ecosystems, such as temperate grasslands, are

underrepresented and many species have no habitat in reserves (Brooks et al.

2004b; Rodrigues et al. 2004a, b; Chape et al. 2005; Hoekstra et al. 2005). Most

notably, reserves cover only 0.5% of the oceans and 1.4% of the coastal shelf

areas (Chape et al. 2005). The blanket of protection also does not look so comforting

when you consider the types of protected areas (Table 11.1); less than half of

the coverage is in the best protected categories (Types I–IV) (Chape et al. 2005;

Hoekstra et al. 2005).

The 10–15% figure was based on a rather generic recommendation that the

extent of the world’s protected areas (about 4–5% at that time) “needs to be at

least tripled” (World Commission on Environment and Development 1987).

Recommendations from other sources have ranged from 5% to 99.7%, with a

rough convergence on 50% depending on the goals and the ecosystems or taxa

being considered (Noss and Cooperrider 1994; Soule and Sanjayan 1998; Neel

and Cummings 2003; Solomon et al. 2003). Obviously, there is no one correct

answer. For example, the minimum area for a network of reserves would depend

on whether they were surrounded by seminatural ecosystems or built and cultivated

ecosystems.

Logistical issues

Thus far we have focused on the biological values that would characterize a potential

reserve: a representative array of ecosystems, high species richness, endemic or rare

species, etc., but this is not the entire story. We must also consider a number of logistical

issues (Usher 1986; Groves 2003). For example, the threats that face a potential

reserve are a critical consideration because a landscape that is under imminent threat

of degradation may be considered a higher priority than a remote landscape that

seems safe for the time being. On the other hand, if the threat is too severe then the

situation might be deemed a lost cause and a safer site would be preferred.

Furthermore, the feasibility of creating a reserve in an area under imminent threat is

often challenging because typically land will cost more and some people will oppose

creating a reserve. Having a single landowner who is willing to sell land at a low cost

is the ideal scenario but this is uncommon in areas with dense human populations.

Similarly, allocating government-owned land to a reserve will be more controversial if

there are many stakeholders living nearby. The current condition of the area is an

important consideration too: maintaining a relatively pristine area is far easier than

restoring a degraded area, as we will see when we address ecological restoration in the

next chapter. Some of these issues can be ameliorated by the design of a reserve, the

subject of the next section.

234 Part III Maintaining Biodiversity

Reserve Design

Reserve selection is inevitably followed by reserve design: deciding

how large the reserve should be, where its boundaries should lie, and

other issues. Many ideas about reserve design can be traced back to a

1975 paper in which Jared Diamond made an analogy between

reserves and islands and proposed six design features for reserves

based, in part, on island biogeography theory (Fig. 11.5):

1 A large reserve will hold more species than a small reserve because

of the species–area relationships described in Chapter 8.

2 A single large reserve is preferable to several small reserves of equal

total area, assuming they all represent the same ecosystem type.

3 If it is necessary to have multiple small reserves, they should be

close to one another to minimize isolation.

4 Arranging small reserves in a cluster, as opposed to a linear fashion,

will also facilitate movement among the reserves.

5 Connecting the reserves with corridors will make dispersal easier

for many species.

6 By making reserves as circular as possible, dispersal within the

reserve will be enhanced, and the negative effects of edges (see

Chapter 8) will be minimized.

These ideas were soon widely accepted even though a number of the

points have been challenged (e.g. Kunin 1997) and one – that a single

large reserve is better than several small ones of equal total area – generated

a heated controversy. We will address these points and others in

three sections on reserve size, landscape context, and connectivity.

Reserve Size

Conservationists prefer large reserves to small reserves for two main reasons. First,

large reserves will, on average, contain a wider range of environmental conditions

and thus more species than small reserves. Additionally, some species will be absent

from small reserves because they require large home ranges (e.g. large carnivores), or

simply because they live at low densities and by chance alone are unlikely to be in a

small reserve (e.g. many rare plants). In both cases, these are species that are likely to

be high priorities for conservation. (See “Fragmentation” in Chapter 8 for further discussion

of these ideas.)

Second, large reserves are more secure and easier to manage (at least per unit area)

than small reserves for three reasons: (1) large reserves have relatively large populations

that are less likely to become extinct (recall Chapter 7); (2) large reserves have a

relatively shorter edge than small reserves and thus are less susceptible to external

disturbances such as invasions of exotic species and poachers (recall Fig. 8.15); and

(3) large reserves are less vulnerable to a catastrophic event such as a volcanic eruption,

hurricane, or oil spill because most catastrophes cannot disturb an entire reserve

Protecting Ecosystems 235

Figure 11.5 Schematic representations

of design principles for

nature reserves. In each pair the

design on the left will probably

have a lower extinction rate and

thus may have higher species

diversity. (Redrawn by permission

from Diamond 1975.)

236 Part III Maintaining Biodiversity

BOX 11.1

Single large reserve or several small1

To illustrate the fundamental difference between the alternatives “single large or several small,” Table 11.2 depicts

two extreme cases. Diamond’s approach would be supported if Scenario 1 described the real world. Each successively

larger reserve contains all the species of the smaller reserves plus additional species in a pattern that is called perfect

nestedness, i.e. the species list for each reserve nests within the list for larger reserves. There is a predictable gradient

among the species, from daisies that are found in all the reserves to hawks that need so much land that they can

survive in only the 240 ha reserve. In this situation, if you were given $1,200,000 to save forests from being turned

into parking lots and if land cost $5000 per hectare, you should buy the 240 ha reserve and thus maintain 224

species. For the same amount of money you could buy reserves D, E, and F, but you would protect only 199 species.

Scenario 2 describes a situation that would definitely favor the Simberloff approach. Again, large reserves have

more species, but each reserve has a unique set of species, a more or less random selection from the species pool, so

there is no nestedness at all. Here, the best approach would be to buy reserves A, B, C, D, and E; they would harbor

709 species and cost just $750,000. The G reserve would still cost $1.2 million and only have 224 species.

Clearly, neither of these scenarios describes the real world, but which is more accurate? A statistically significant

pattern of nestedness has been documented for a variety of taxa, even small species such as butterflies (Fleishman

and Murphy 1999) and fungi (Berglund and Jonsson 2003), and this would suggest support for the “single large”

perspective. However, patterns of nestedness are usually confounded by environmental patterns (Fleishman and

MacNally 2002) and there can be large differences between a significantly nested set of species and a perfectly nested

if it is large enough. All three of these factors, especially the second one, make large

reserves easier and cheaper to manage per unit area. There are also efficiencies of

scale in supporting the management infrastructure of a large reserve (e.g. almost

every reserve, large or small, needs a headquarters building).

The issue of natural catastrophes needs to be clarified. It is important that natural disturbances

such as fires be allowed to shape reserves (we will return to this issue below

when we discuss reserve management). This means that reserves need to be large

enough not to be profoundly changed by a single disturbance event. This concept led

Pickett and Thompson (1978) to suggest that reserves should be larger than the minimum

dynamic area, the smallest area that would hold an array of patches representing

different stages of disturbance and succession. For example, if a landscape was characterized

by fires covering 1000 hectares, a reserve for this landscape should be many

thousands of hectares to contain a series of patches representing burns of different ages.

Reserve size was central to a well known debate that erupted shortly after

Diamond’s paper was published, a debate known by the acronym SLOSS, Single Large

or Several Small (Diamond 1976; Simberloff and Abele 1976a, b, 1982; Terborgh

1976; Whitcomb et al. 1976). The controversy began when Daniel Simberloff,

Lawrence Abele, and others expressed some doubt about Diamond’s second principle.

They did not believe that there is a simple, universal answer to the question: if you

have a finite amount of money, should you buy one large nature reserve or several

small ones of equal total area? Defenders of Diamond’s model have sometimes reacted

as though the first design principle – large reserves are better than small reserves –

was under attack, and have even accused the opposition of advocating the dismembering

of nature reserves (Simberloff and Abele 1984; Willis 1984). In Box 11.1 this

Table 11.2

A hypothetical

series of seven

progressively larger

reserves.

Patch Number Number of Accum. no. Representative

size (ha) of species new species of species species

Scenario 1

A(10) 119 – 119 Daisy, etc.

B(10) 119 0 119 Daisy, etc.

C(20) 137 22 137 Daisy, sparrow, etc.

D(40) 159 16 159 Daisy, sparrow,

snake, etc.

E(70) 175 24 175 Daisy, sparrow,

snake, robin, etc.

F(130) 199 25 199 Daisy, sparrow,

snake, robin, squirrel, etc.

G(240) 224 25 224 Daisy, sparrow, snake,

robin, squirrel, hawk, etc.

Scenario 2

A(10) 119 – 119 Daisy, etc.

B(10) 119 119 238 Sparrow, etc.

C(20) 137 137 375 Ivy, grackle, etc.

D(40) 159 159 534 Trillium, blackbird,

tortoise, etc.

E(70) 175 175 709 Lily, toad, rabbit,

shrew, etc.

F(130) 199 199 908 Holly, snake, warbler,

mouse, pine, etc.

G(240) 224 224 1132 Robin, lizard, frog,

squirrel, fox, hawk, etc.

The series is described with the area of each reserve (column 1), the total number of species in each reserve (column

2), the number of new species added to the series total by each reserve (column 3), and the accumulative number of

species in the series (column 4). The last column gives a hypothetical sample of the species found in each reserve. In

Scenario 1 each reserve has all the species of the smaller reserves plus some new species. Each reserve has the same

area as the total of the three preceding reserves. Species numbers were calculated from S = CAz with C 75 and z 

0.2; this might roughly approximate the number of vascular plant and vertebrate animal species in a temperate forest.

one (i.e. perfect nestedness does not occur and thus some species found in small reserves are missed by large

reserves [Fischer and Lindenmayer 2005]). Consequently, most people would argue that there is an important role

for small reserves too, at least as complements to large reserves (Gotmark and Thorell 2003). Furthermore,

Diamond’s assertion that one large reserve is superior to several small ones explicitly assumes that all the reserves

represent the same type of environment, and this will not usually be true, at least at a microenvironmental scale.

1 Modified from Hunter (1990).

question is explored in detail; suffice it to say here that no consensus on the correct

answer has been reached beyond an ambiguous compromise position: “Nature

reserves should be as large as possible, and there should be many of them” (Soule and

Simberloff 1986). The key question behind SLOSS is still alive among conservation

practitioners although the SLOSS debate has disappeared from the conservation literature,

partly because academics grew tired of arguing about a question for which

there was no clear answer, and partly because, in practice, reserve size will be determined

by a complex amalgam of ecological, political, and fiscal realities that make

every situation unique.

Landscape Context

Although it is common to think of reserves as sacrosanct refuges – islands of nature

isolated in a sea of human-altered ecosystems – this is not an accurate view. The

boundaries of reserves are permeable and many things move across them (Janzen

1986). Air and water pollution, invasive exotics, livestock, and poachers are some of

the negative factors that can impinge on reserves from outside. On the positive side,

reserves often export clean air and water and are a source of individual organisms that

can bolster low populations outside the reserve. For example, proponents of marine

reserves have argued that fishing outside reserves is improved because breeding stocks

in the reserves produce offspring that are caught outside the reserve (Palumbi 2004;

Roberts et al. 2005). Some of the movements into a reserve are positive too, especially

because many reserves are so small that they would probably lose their populations of

some species if they were not part of a metapopulation with individuals regularly

exchanged with ecosystems outside the reserve (Chapter 7). In short, reserve designers

must pay careful attention to what will lie outside a reserve when deciding where to

put its boundaries.

One obvious idea is to design reserves so that they will be buffered from the

most harmful human activities by being imbedded in a matrix of seminatural ecosystems

such as native forests managed for production of large trees (Lindenmayer

and Franklin 2002). Dense human populations (some of whom might be poachers)

and incompatible land uses such as intensive agriculture would be kept at a

distance from the reserve (Brashares et al. 2001; Wiersma et al. 2004)

(Fig. 11.6).

Reserves are easier to buffer if they are fairly circular, because a circle has less edge

per unit area than any other shape. Keoladeo Ghana National Park in Bharatpur,

India, one of the world’s premier bird reserves, is surrounded by a high brick wall

about 35 km long. However, if the 29 km2 reserve were circular, the wall would only

be 19 km long and far easier to patrol and maintain.

Buffering is also easier if the reserve boundaries correspond with certain natural

boundaries such as shorelines and ridge tops. Watershed lines are often excellent

reserve boundary lines because a reserve that fully occupies a single watershed

will have relatively few problems with water quality and quantity, and it will be a

cohesive unit of habitat for many aquatic species. In practice, reserve boundaries

are more likely to follow a political or ownership boundary than a natural

boundary. In an interesting twist on buffering, many reserves are located along

238 Part III Maintaining Biodiversity

Protecting Ecosystems 239

international frontiers to provide a strategic military buffer in case of war. The most

conspicuous example of this is the de facto reserve that now exists in the demilitarized

zone between North and South Korea, providing habitat for two very rare

birds, the Japanese and white-naped cranes, as well as for many other species (Kim

1997).

The importance of context, especially integrating reserves with well managed seminatural

ecosystems, is so great that many conservationists prefer to think about planning

entire conservation areas at a landscape scale rather than designing reserves

per se (Groves 2003) (Fig. 11.7), and this will involve many of the practices we will

discuss in the next chapter on “Managing Ecosystems.”

Connectivity

In a Panglossian “best of all possible worlds,” reserves would be so large that they

would adequately protect even the most demanding species, or they would be completely

surrounded by carefully managed seminatural ecosystems through which

Figure 11.6 The reserve depicted in the center of this drawing illustrates many desirable features, although it is

fairly small for ease of illustration. It encompasses a wide range of ecosystems spanning elevations from river level

to mountaintop. It fully occupies a watershed by lying within natural boundaries, the watershed line and river

shore, and is fairly circular in outline. It is buffered by seminatural forests from plantation forests, and by plantation

forests from agriculture. It is connected to other reserves by natural vegetation along both the mountain

slope and the river shore.

240 Part III Maintaining Biodiversity

Figure 11.7 Final zoning plan for the Asinara Island Marine Reserve in Italy, which shows

how core protected areas can be buffered by zones in which some uses are allowed. In

both zones A1 (no-entry, no-take) and A2 (entry, no-take) no fishing is allowed; only

park personnel are allowed in A1 for research and management. Zone B (general reserve)

is open for recreation and fishing but with special limits on fishing, while in zone C (partial

reserve) a greater range of fishing activity (both commercial and recreational) is

allowed. (From Villa et al. 2002.)

species could easily move from reserve to reserve. In the real world, very few reserves

are large enough to protect their complete biota, and the landscapes around reserves

are likely to be degraded further as human populations increase (Newmark 1996;

Carroll et al. 2004). In the face of these realities, conservation biologists often stress

the importance of maintaining connectivity among reserves, perhaps with broad

swaths of seminatural ecosystems, perhaps with corridors, linear strips of protected

land (Beier and Noss 1998).

Four basic kinds of movement need to be maintained (Hunter 1997). First are the

daily movements most animals make among the patches of preferred habitat that

comprise their home range. These are relatively small-scale movements, and most

reserves are large enough to encompass them except for wide-ranging species like

large carnivores and some colonial birds and bats.

Second are the annual migrations many animals make between winter and

summer ranges, or dry season and wet season ranges. The lengths of these

Protecting Ecosystems 241

movements vary from a few hundred meters for some amphibians and insects to

thousands of kilometers for some birds and marine animals. For migration over

intermediate distances, e.g. herds of large mammals moving between high-altitude

summer range and low-altitude winter range, connecting reserves could be of

critical importance (Berger 2004). In Tanzania conservationists are trying to

protect land between two national parks, Lake Manyara and Tarangire, to allow

zebras, wildebeest, and other antelopes to move to Lake Manyara in the dry

season (Mwalyosi 1991). For long-distance migration, notably by birds, it is

important to think of reserves as stepping-stones along their routes where they

can rest and forage to refuel.

Third are the dispersal movements that young animals and plants (the

latter usually as seeds, spores, or pollen) make away from their parents.

Dispersal movements are vital to keeping the organisms of a reserve “connected”

with conspecifics living elsewhere. Imagine a reserve with ten tigers. As long as

tigers are freely dispersing in and out of the reserve, the reserve’s tigers are part

of the whole region’s tiger population, say 300 tigers, and thus relatively safe

from the problems that afflict small populations. Without dispersal the reserve’s

ten tigers constitute an isolated, and very vulnerable, population. See Fig. 11.8

for a real world example involving tiger dispersal. Of course, dispersal ecology

varies greatly among species: some species can easily disperse long distances

over any terrain (e.g. fungi spores), but others cannot; some species can persist

in small isolated populations with no immigration (e.g. fish species confined to a

single spring or cave), but others cannot (Bullock et al. 2002). Dispersal can be

a difficult phenomenon to study but it clearly affects the viability of many

populations (Chapter 7), especially for animals, and thus maintaining

dispersal is a major goal of conservation biologists.

Fourth are the range shifts that species make in response to climate change,

moving back and forth across continents at time scales measured in thousands of

years (Chapter 6). No refuges are large enough to accommodate continental-scale

movements, but conservationists have considered linking reserves with continentalscale

corridors, or at least having reserves arranged as stepping-stones across a

continent (Hunter et al. 1988). In mountainous areas, species can respond to

climate change by shifting their altitude; therefore linking reserves at different

altitudes would deal with this issue in montane environments.

Naturally, the design of a connection should depend on the kinds of

organisms and the types of movements it was intended to accommodate.

A connection designed to accommodate short-range movements by relatively

mobile animals may only need to provide some cover or the right microclimate.

To take an extreme example, eastern chipmunks will move among isolated

woodlots along a barbed-wire fence with a narrow strip of uncut grass and

herbs (Henderson et al. 1985), while, conversely, butterflies will move among

forest clearings using narrow openings (Haddad and Tewksbury 2005).

Connectivity in the context of marine reserves may mean locating reserves

strategically with respect to oceanic currents that transport organisms, especially

larvae and propagules (Roberts 1997). A connection designed to allow large-scale

movement by organisms that are relatively sedentary (e.g. terrestrial snails and

many plants) would have to provide habitat in which the species could live and

242 Part III Maintaining Biodiversity

Figure 11.8 The top map depicts core areas of tiger habitat in the terai region of India

and Nepal in green colors (NP, national park; TR, tiger reserve; WR, wildlife reserve; WS,

wildlife sanctuary). The potential for dispersal is indicated, with darker reds representing

areas with the lowest biological costs for dispersal (e.g. good food and cover) and yellows

representing areas with higher biological costs. The bottom map shows potential

tiger dispersal corridors, with Level 1 corridors representing the best pathways for dispersal

(as defined by low biological cost), Level 2 corridors representing the next best pathways,

and Corridor Buffers the next best. Existing tiger subpopulations are delineated by

the dashed line. (From Wikramanayake et al. 2004.)

reproduce, because it might take multiple generations for a species to move. It

will often make sense to “piggyback” connections onto other efforts to maintain

linear belts of natural vegetation such as hiking trails and riparian zones.

Riparian zones are particularly attractive in this context because they form a

natural landscape network and have so many other values, such as protecting

water quality.

One common manifestation of the connection idea – protecting narrow corridors

between reserves – has been widely criticized (Simberloff and Cox 1987; Simberloff

et al. 1992; Knopf and Samson 1994), particularly with respect to cost effectiveness.

A strip of land 0.5 km wide by 50 km long is likely to be much more difficult to purchase

and manage than a compact area of the same size because it will cross many

ownerships. Furthermore, corridors are particularly vulnerable to external disturbances

because of their shape, and they may even facilitate the spread of diseases

(Lomolino et al. 2004) and exotic species from one reserve to another. Perhaps the

most convincing argument in favor of corridors is that natural landscapes are far

more connected than those heavily shaped by humans (Beier and Noss 1998). How

well this argument stands up in the real world of limited monies for conservation is

an open question. This argument also leaves unanswered the question of which

will maintain connectivity more effectively: a narrow corridor of natural vegetation

or a broad swath of seminatural ecosystems such as forest managed for timber

production.

Reserve Management

Once a reserve has been selected and its boundaries laid out, the hard work

begins, for you cannot simply “lock the gate and throw away the key.” Here we will

review a few of the many problems that make reserve management a challenging

career.

Human Visitors

Most reserves are open to visitors; indeed, most reserves would not exist if they did

not provide opportunities for outdoor recreation. Unfortunately, the number of

human visitors can be overwhelming, with some parks attracting over a million

visitors per year. This means that reserve management encompasses all the

problems that accompany entertaining large numbers of people: proliferation of

roads, air pollution, sewage disposal, plant trampling, soil erosion, and so on.

Simply put, reserve management is, first and foremost, people management.

Because most reserves are not routinely open to hunting, cutting trees, and

so on, it is often assumed that controlling direct exploitation of wild life is not

an issue. In fact, few reserves are closed to absolutely all forms of exploitation.

One widespread exception is sportfishing. Reserve managers usually allow

visitors to fish even in reserves where hunting is strictly forbidden, presumably

because fish are generally out of sight and lack charisma, and, unlike hunters,

anglers pose no danger to other visitors. This acceptance of fishing carries over

to marine reserves, very few of which are closed to all fishing. A second

common exception is allowing people to gather deadwood for firewood, despite

Protecting Ecosystems 243

a growing appreciation of the importance of deadwood as habitat for myriad

small organisms (McComb and Lindenmayer 1999). Of course, simply

having large numbers of people visit an area can disturb wild life and

constitute “nonconsumptive exploitation” as described in Chapter 9

(Fig. 9.6).

To be successful, reserve managers must always foster the good will of local

people, but in developing countries the people who live near a reserve are

often too poor to spend a weekend enjoying its recreational amenities. To give

these people a vested interest in the reserve, managers often allow some limited

forms of exploitation. In Chitwan National Park in lowland Nepal, local people

are allowed to enter the park once a year for ten days during the dry season to

collect dead grass, some of which stands 5 meters tall (Straede and Helles

2000). Traditionally, they used the grass to thatch roofs, and, like bamboo,

for construction, but now most of it is sold to a paper mill for pulp. This grass

harvest generates some good will, but it does come at a cost in terms of small

logs stolen from the park for firewood. Such activities become much more

controversial if the exploited resources are birds, mammals, and live trees as

opposed to fish and dead plants (Bruner et al. 2001). Local people will also be

favorably disposed toward a reserve if they can derive an income by providing

services for visitors (Bookbinder et al. 1998). Unfortunately, in many

developing countries, tourist facilities are owned by people who live far from

the reserve, in cities or even overseas. For example, when a European or

American tourist pays several thousand dollars to visit Africa’s spectacular

parks, most of that money never goes to Africa at all, and extremely little reaches

the people who live near the reserve. This remains a fundamental problem with

linking the benefits of ecotourism to local conservation. Moreover, it explains why

local people, who bear the costs of protected areas but often receive little of the

benefits, are typically ambivalent or even hostile toward the creation of new

reserves.

Natural Disturbances

Fires, floods, hurricanes, insect outbreaks, and earthquakes are some of the

many unpredictable natural events that can shape reserve management. In the

past, reserve managers often viewed such events as unmitigated catastrophes

that upset the balance of nature they were trying to protect. More recently, most

reserve managers have come to understand that disturbances are often critical in

maintaining the natural structure and function of ecosystems, and that

suppressing disturbances can soon degrade a reserve. This revelation has not

made the job of reserve managers any easier. Indeed, it has made it more difficult

because the public does not understand the ecological role of natural disturbances

and will often question the wisdom of a reserve manager who accepts

disturbances.

Some disturbances cannot be controlled (volcanic eruptions, earthquakes,

hurricanes, tornadoes), but reserve managers still have to decide what to do

after the disturbance. Should they replant vegetation, stabilize eroding slopes,

244 Part III Maintaining Biodiversity

and so forth, or let it be? Wild fires are particularly challenging because they

are essential elements in many ecosystems (Baker 1992; Nordlind and

Ostlund 2003) and, to some extent, controllable. Reserve managers cannot

simply shrug their shoulders and say “It’s out of my hands” because small fires

can be put out, and the movement of large fires can often be controlled with

firebreaks. Reserve managers can even set fires, choosing locations and

weather conditions that will allow them to determine how large and hot a fire will

become.

Fire frequency is a key issue for reserve managers. Sometimes, fires happen at

fairly regular intervals when sufficient fuel accumulates; sometimes, fires occur

only at long, unpredictable intervals determined by droughts; if both fuel

buildup and droughts need to coincide, then the frequency of fire may be neither

totally random nor predictable. Often, reserve managers do not know what

the natural fire frequency is for their reserve, and, anyway, it will change over

time as the climate changes (McKenzie et al. 2004). If fire frequency is quite

short (e.g. in many grasslands and woodlands where only a few years elapse

between fires on average), reserve managers will probably have many

opportunities to let natural fires burn or to set fires. In ecosystems that tend

to burn at longer intervals (every several decades or centuries) it is tempting to

suppress fires. This was the policy in Yellowstone National Park from 1872 to

1972, and some ecologists have blamed this policy for the severity of the 1988

fires, which burned over 321,000 ha in the park. It makes sense that a long

history of suppressing fires could lead to an artificial buildup of fuels, but in

this case the park’s suppression policy may not have contributed to the 1988

burn. By analyzing fire-scarred tree rings and other information ecologists

have determined that fires comparable with those in 1988 also burnt the area

in the early eighteenth century (Romme and Despain 1989; Schoennagel et al.

2004).

Water Regimes

Reserve managers often find themselves embroiled in an argument over water.

Usually, the issue is relatively straightforward: the supply of water is limited, and

someone wants to reduce the reserve’s share and allocate more water to irrigating

crops, turning power turbines, or flushing toilets. Sometimes, things are more complicated.

For example, managers of the Everglades National Park seeking to restore

some semblance of the park’s natural water regime – a broad sheet of freshwater

that flows slowly south from central Florida through the park – have encountered a

number of cases where they must balance competing needs of different species

(Davis and Ogden 1994; Sklar et al. 2005). In one case, restoring some of the

Everglades’ flow has reduced water availability in an area outside the park that had

become prime habitat for the Everglades snail kite, an endangered subspecies

(Curnutt et al. 2000). Manipulating water regimes of wetlands is also a major activity

for natural resource managers who wish to maximize waterfowl production by

providing optimum mixtures of water and vegetation (Payne 1992). These waterfowl

sanctuaries are important habitat for many species, but it could be argued that

Protecting Ecosystems 245

conceptually they are closer to the modified ecosystems we will discuss in the next

chapter than to nature reserves.

Water management on reserves is also an issue in arid lands, where reserve managers

have a long tradition of digging wells to provide water for wild animals. These

artificial water holes tend to increase the abundance of animals overall, and particularly

avoid population crashes during droughts. They also make it much easier for visitors

to watch wild animals. Think about all the African nature films you have seen

with elephants and lions coming and going from a water hole. Many arid reserve

managers now question the wisdom of digging wells (James et al. 1999; Thrash

2000). If artificial water holes increase wild animal populations, what are the effects

on other species – plants that the animals graze or animals that are not dependent on

water holes? What are the effects of concentrating animals on disease transmission

and social relationships?

Invasive Exotics and Overabundant Natives

Many reserves have populations of exotic species that reserve managers would like

to eliminate: goats in the Galapagos, Brazilian peppers in the Everglades, and rats in

the New Zealand Alps to name just three. Similarly, some reserves have very large

populations of certain native species that managers would like to sharply reduce.

Notably, many small reserves have unnaturally large numbers of herbivorous mammals

such as deer because the reserve is too small to harbor large carnivores, and

these animals wreak havoc on the reserve’s flora (Cote et al. 2004). In some aquatic

reserves, geese have become a problem by moving huge quantities of nutrients from

the surrounding farmland, where they feed, to the water bodies where they roost

(Olson et al. 2005).

Eliminating exotic species and reducing the population of a native species are

challenging tasks because of both logistical and political constraints. Logistically,

controlling a successful species can be exceedingly difficult, as we will see in

Chapter 13, “Managing Populations.” Suffice it to say here that the scope of the

problem is suggested by the billions of dollars farmers spend to control weeds

and pests.

Political difficulties are also nearly inevitable, especially if most people are fond of

the species in question. Public affection has curtailed many programs to control

appealing creatures such as deer, burros, and horses. Public opposition can also be

catalyzed by aversion to the proposed methods. Shooting birds and spraying plants

with herbicides are sure to provoke a negative reaction, whereas destroying bird eggs

and digging up plants may not.

Although these issues present daunting challenges, reserve managers can overcome

them. New Zealand biologists have learned how to eliminate rats and other

exotic mammals from islands that are the only remaining habitat for many bird,

reptile, and insect species eliminated from the main islands. They started poisoning

and trapping campaigns on some very small islands (fractions of a hectare) and

have been progressing to larger and larger islands, some measuring thousand of

hectares (Towns et al. 1990, 1997, Courchamp et al. 2003, Towns and Broome

2003).

246 Part III Maintaining Biodiversity

Protecting Ecosystems 247

CASE STUDY

Vietnam Conservation Areas

Eleanor J. Sterling,1 Martha M. Hurley,1 Andrew Tordoff,2

and Jonathan C. Eames3

Have you heard of the saola, Annamite striped rabbit, or golden-winged laughingthrush? If not, you are not alone,

for these species were unknown to science just 15 years ago, and we still know virtually nothing about them

(Fig. 11.9). Along with three turtles, nine lizards, four snakes, over 25 frogs, and additional mammals and birds,

these species have all been discovered in the Annamite mountain range separating Vietnam and Laos since 1992

(e.g. Eames et al. 1999; Inger et al. 1999; Surridge et al. 1999; Groves and Schaller 2000; Ziegler et al. 2000;

Stuart and Parham 2004; Sterling et al. 2006). These discoveries were one of several reasons why, in 1998, the

government of Vietnam proposed increasing the protected-area forest network from 1.3 to 2 million hectares. To

identify where these new conservation areas should be located, researchers conducted a gap analysis (Wege et al.

1999; Eames and Tordoff 2001).

A gap analysis is a priority-setting technique that provides a preliminary, landscape-scale overview of

the distribution and conservation status of species and ecosystems. It identifies “gaps,” vegetation types,

What Is Natural?

Fire regimes, water regimes, management of abundant native species, and many

other issues facing reserve managers often lead to the question: what is natural?

Typically, the question arises after some more specific questions are asked first,

such as: How does the current density of deer on this reserve compare with what

it was 200 years ago? Is 200 years ago the right benchmark to be using just

because that is when people with modern technology began to colonize this

region? Or should it be thousands of years ago, before there were any humans

here? This is a complicated issue that quickly moves into philosophical debates

about the role of humans in ecosystems (Hunter 1996; Angermeier 2000; Povilitis

2002). Suffice it to say here that many people would take a purist view and advocate

that natural reserves should be managed to minimize human influences as

much as feasible. On the other hand, many people would argue that humans and

ecosystems are so inseparable that it is reasonable to manage reserves for whatever

condition society deems desirable. For example, many European reserves strive to

maintain traditional land-use practices (e.g. livestock grazing regimes) that were

common before the advent of industrial agriculture and forestry (Sutherland and

Hill 1995).

248 Part III Maintaining Biodiversity

ecoregions, species, or other elements of biodiversity

that are not represented in a protected-

areas network. Gap analyses often use

the distribution of vegetation types and

selected species (usually well known groups

like mammals and birds) as surrogates for

biodiversity in general (Scott and Jennings

1998; Scott et al. 2001).

There are three key steps in a gap analysis:

(1) creating maps of an area showing the distribution

of vegetation cover and of selected

species, along with other features of interest

such as elevation, slope, aspect, soils, aquatic

features, climate, or socioeconomic data, as

well as areas currently managed primarily for

biodiversity; (2) overlaying these different maps

to identify gaps in the protected-areas system;

and (3) determining priorities for conservation

action by placing the results within the context

of other factors, such as ecosystem patch

dynamics, habitat quality, population viability

analysis, distribution of threatened species,

the feasibility of creating a reserve in the area,

and the importance of having multiple representations

of species or ecosystems throughout

their geographic range to protect against

potentially catastrophic stochastic events.

In 1996 there were 90 protected areas in

Vietnam – 10 national parks, 53 nature

reserves, and 27 cultural and historical sites –

covering 1,345,000 ha (equivalent to 4% of the

land area of Vietnam). These protected areas

were all terrestrial sites, mainly forested, with a

small number of wetland areas; comprehensive,

protected-areas networks for wetland and

marine sites had yet to be developed. For the gap

analysis, researchers mapped datasets for seven

natural forest types; 13 ecoregions; four elevation

zones; a subset of globally threatened large

mammals, primates, and birds; existing protected

areas; and political provinces. Results

showed that almost half (575,000 ha) of the

existing protected-areas network encompassed

nonforest land – principally, agricultural land,

scrub, and non-natural grassland.

Figure 11.9

Recently described

vertebrate species

from the Annamite

Range include:

Morafka’s cascade

frog (top) and Ba

Na cascade frog

(third from top)

(Bain et al. 2003);

Large-antlered

muntjac (second

panel, left)

(Schaller and Vrba

1996); Annamite

muntjac (second

panel, right) (Pham

Mong Giao et al.

1998); Annamite

striped rabbit (second

from bottom)

(Averianov et al.

2000); and saola

(bottom) (Vu Van

Dung et al. 1993).

Also pictured are

species closely

related to these

newly described

ones: green cascade

frog (second

from top) and red

muntjac (middle

panel: female on

left, male on right).

(Paintings by Joyce

A. Powzyk, ©

Center for

Biodiversity and

Conservation,

American Museum

of Natural History.)

Protecting Ecosystems 249

Figure 11.10 As

of 2004, Vietnam’s

protected area

network covered

approximately 1.7

million ha (5% of

the country); if all

the conservation

areas currently

proposed were

approved, coverage

would increase

to roughly 2.5 million

ha, or around

7.5% of the land

area, exceeding

the goals proposed

in 1998. (Map produced

by Kevin

Koy, American

Museum of Natural

History.)

Next, researchers identified areas that fulfilled representation criteria for these variables and refined their

selection by considering the need to include: globally threatened species currently underrepresented within the

network; large areas of contiguous natural forest; sites contiguous with other protected areas, including those in

other countries; provinces in need of further protection; and existing, well documented proposals for protected

area development.

As a result of the analysis, researchers recommended the addition of 25 conservation areas to the current,

protected-areas forest network, including the creation of 14 new protected areas and the extension of 11 existing

ones (Wege et al. 1999). These expansions would add more than 750,000 ha to the current network and

increase coverage of all forest types to a minimum of 15% (evergreen forest coverage had previously been only

8.2%). Protected areas would be established in three political provinces that currently have none, and a large

number of globally threatened bird and mammal species would have increased protection in the expanded

network.

250 Part III Maintaining Biodiversity

Summary

Often the most reliable way to conserve the biodiversity of ecosystems is to

protect them in a reserve (also known as park, refuge, sanctuary, protected

area, etc.) The first step is to select reserves that will protect a large number of

targeted species and/or a representative array of ecosystems, and this is likely

to involve filling in the gaps in an existing reserve network by selecting new

reserves that complement existing ones. Logistical considerations such as the

degree of threat, current condition, and feasibility will also affect selection

decisions. Designing reserves chiefly involves deciding on their size, shape, and

location with respect to other types of ecosystems; it is particularly desirable that

they sit in a landscape context that connects them to other reserves and buffers

them from threats. Managing reserves to maintain their natural structure and

function often will require controlling human visitors, exotic species (and sometimes

overabundant native species), water distribution, and natural disturbance

regimes, notably fires.

FURTHER READING

For a grand overview on protecting and managing ecosystems see Groves (2003) and United Nations

Development Programme et al. 2003). For regional perspectives see Lindenmayer and Burgman (2005) for

Australia, Noss and Cooperrider (1994) for North America, and Sutherland and Hill (1995) for Europe. See

www.unep-wcmc.org for the World Conservation Monitoring Centre’s work on protected areas and habitats. See

worldwildlife.org/wildfinder/printableMaps.cfm for more maps like Fig. 11.1.

As of 2004 Vietnam had made some progress in expanding the terrestrial conservation network (BirdLife

International and MARD 2004). There are now 96 protected areas and revisions in management categories have

raised the number of National Parks from 11 to 27. Significant extensions have also occurred at some of the

country’s most important protected areas (Yok Don and Ke Bang), almost doubling their size. The Forest

Protections Department’s proposed list of expansions would bring the total number of protected areas to 121 by

2010 (Fig. 11.10).

A more sophisticated gap analysis would go well beyond equitability of representation and would weigh

ecoregions by variables affecting their importance and priority, such as threat level, global uniqueness,

regional uniqueness, maintenance of migratory corridors, the potential for effective conservation strategies,

and other considerations (Timmins and Trinh 2001; W. Duckworth, personal communication). Such an analysis

would also include datasets on distribution of other animal species, such as threatened frogs and invertebrates

and flora.

1 Center for Biodiversity and Conservation, American Museum of Natural History.

2 BirdLife International Asia Division.

3 BirdLife International Indochina Programme.

Protecting Ecosystems 251

TOPICS FOR DISCUSSION

1 Are you more comfortable selecting reserves on the basis of species distributions or

ecosystems distributions?

2 Find a map of a nearby reserve. If you had a million dollars to spend on land conservation

near this reserve, which would be easier, to better buffer it from threats or to connect

it with other natural areas?

3 Given finite resources, is it generally better to create large new reserves in remote

areas or smaller ones in more densely populated areas? To take an extreme example

would it be better to create a million hectare reserve in the high Arctic or a 10,000

hectare reserve near Hong Kong?

4 Would you create artificial water holes in arid reserves? Would you remove existing artificial

water holes?

5 Should natural ecosystems disturbed by natural events, such as a hurricane or volcano,

be restored? What if not restoring the ecosystem would lead to the extinction of a

species?

6 Should we purchase more reserves or manage better the ones we have?

e eBook Collection chapter 17

Talk is easy. So is hand-wringing. Solving problems is more difficult. Conserving

biodiversity is, in fact, all about problem solving. As such it requires action.

Conservationists must try to shape human institutions to make them more compatible

with maintaining biodiversity. Broadly speaking, politics is the art and science of

governing human institutions, and thus conservationists must be political if they

wish to advance their agenda.

The interface between conservation and politics is a complex landscape that can

be explored in many ways. First, it must be recognized that politics and action

inevitably occur within severe constraints on resources available for conservation

work, chiefly time and money. That means setting priorities, which is the focus of

the first part of this chapter. Next we must determine who has rights and responsibilities

for conserving biodiversity. To do so, we take a relatively short and simple

route that touches on what different types of human entities – international agencies,

governments, nongovernmental organizations, corporations, communities,

and individuals – can do to foster biodiversity conservation and what their responsibilities

are. Some approaches described are of an economic nature and were outlined

in more detail in the preceding chapter; others are not based on economics.

All of these actions are currently being undertaken somewhere, but seldom at an

adequate scope or intensity. We end with a strong message about what you can do

as an individual to make a difference.

Setting Priorities for Action

Conservationists understand the finite natural resources that humans overexploit and

thus it is easy for us to appreciate the resources available for conservation work. We

can and should decry the myopia of social, political, and economic systems that do

not recognize the importance of conserving biodiversity. For example, why do we

spend far, far more money on medical research and treatment than on controlling

environmental pollution when many diseases are primarily symptoms of environmental

degradation? Even within a conservation context, why do we end up paying

dearly for last minute interventions to save a species on the brink of extinction when

it would have been far easier and cheaper to maintain the species’s habitat years ago?

Inevitably, we have to work with what society allocates to us, which often is minimal.

There are many approaches to setting priorities; we will outline seven issues that are

quite different but not mutually exclusive.

CHAPTER 17

Politics and Action

Levels of Biodiversity

Biosphere, biome, landscape, ecosystem, community, guild, species, population, individual,

gene, allele – it is easy to construct hierarchical organizations for life on earth.

In such a hierarchy each level contains more elements of biodiversity than the level

below, making this one logical and simple way to decide which elements of biodiversity

merit primary attention (Noss 1990; Soule 1991; Zacharias and Roff 2000). If

we give priority to protecting a marsh from being destroyed, we protect hundreds,

even thousands, of different species that inhabit the marsh. This is the essential idea

behind the coarse-filter approach to maintaining biodiversity (see Fig. 4.6). In contrast,

if we give priority to protecting a single species, we may be helping only that one

species and a few other species with which it is closely associated. Most conservation

biologists recognize the general wisdom of focusing on organizing conservation

around ecosystems, but sometimes, as we saw in Chapter 11, they debate the merits

of ecosystems versus species as targets for conservation. This largely stems from the

fact that species are more easily recognized as biological entities.

Geographic Scales

It is easy to be parochial, to let your perception of the world revolve around your

day-to-day life. Conservation biologists need to moderate this tendency by asking,

“At what geographic scale is this species or ecosystem at risk?” and then giving priority

to those in jeopardy at large scales, especially the global scale. This is the

alpha, beta, and gamma diversity perspective of Chapter 2 and Fig. 2.3 again. It

merits repetition because it is very important and often ignored. Wealthy countries

often spend large sums protecting species that are threatened within their borders

but that are globally secure (Hunter and Hutchinson 1994; Bunnell et al. 2004).

For example, biologists have labored for over 20 years to restore Atlantic puffins to

some islands on the coast of Maine because there are few Atlantic puffin colonies

remaining in the United States (Kress and Nettleship 1988). Given that Atlantic

puffins number in the millions in Canada, Greenland, Iceland, and Europe, this

effort is not a global priority. On the other hand, it is not a complete waste of time to

save species that are only in danger of local extirpation. Maintaining populations

across a species’s entire geographic range is necessary if its complete genetic wealth

is to be maintained (Lesica and Allendorf 1995; Bunnell et al. 2004; Ficetola and

De Bernardi 2005). Locally endangered species can also be important because of

their ecological, economic, or strategic roles (Chapter 3; Hunter and Hutchinson

1994). Nevertheless, the earth’s biodiversity as a whole would usually be better

served if we could take a truly global perspective when setting priorities. This will

require looking beyond political boundaries that so often constrain our thinking

(Rodrigues and Gaston 2002).

Choosing Areas

When conservation biologists daydream, it is often about winning a huge sum of

money at a lottery that they could then use to buy land and establish nature reserves.

The conservation literature has dozens of papers on how to spend such money wisely

(e.g. Usher 1986; Spellerberg 1992; Noss and Cooperrider 1994; Margules and

Politics and Action 373

Pressey 2000; Myers et al. 2000b; Moilanen et al. 2005; Wilson et al. 2005b; and

papers cited in Chapter 11). Five key criteria emerge from this literature:

1 Size and number: we need both more and larger reserves, and (per the SLOSS

debate described in Chapter 11) are often forced to choose between these goals.

2 Representativeness: the coarse-filter approach (see Fig. 4.6) requires conserving an

array of ecosystems that characterize a region or, from a fine-filter perspective, a

complete array of species’s habitats.

3 Rarity: areas that support rare ecosystems (e.g. aquatic ecosystems in the midst of

an arid region) or habitat for rare or threatened species are a clear priority.

4 Condition: relatively pristine areas are usually preferred over areas that have been

substantially degraded, although exceptions do occur; for example, when purchasing

forest land conservationists might prefer to buy 1000 ha of recently logged forest

if the same amount of money will buy only 300 ha of mature forest.

5 Threat: a reserve that is isolated from potential sources of disruption will probably

be easier to maintain, although conservationists sometimes give higher priority to

areas that are likely to be threatened by human activities in the foreseeable future.

This is not an exhaustive list of criteria. We could add cost, fragility, feasibility,

urgency, and more; see Balmford et al. (2000), Hughey et al. (2003), and Luck et al.

2004 for examples, Usher (1986) and Groves (2003) for reviews, and Ricketts et al.

(2005) for a new approach that puts a strong emphasis on species that are on the

brink of extinction (Fig. 17.1). Finally, it is important to remember that choosing

reserves is only a part of the process of managing areas for conservation. The vast

majority of ecosystems exist outside reserves and it is often wise to think about entire

landscapes where conservation action should be directed (Groves 2003).

Choosing Species

Blue whales or redwoods? Black rhinos or white? One could list dozens of factors to

consider when choosing which species should receive priority, but we will address just

two overarching questions: “Which species is more valuable?” and “Which species is

at greater risk of extinction?”

The first question returns us to Chapter 3 and our discussion of the instrumental

values of species. If our primary concern is the welfare of humanity, we should favor

species with economic values and, because people are dependent on healthy ecosystems,

species with important ecological roles as dominant, controller, or keystone

species. If our concern is more equitably distributed among all species, we should still

focus on species with important ecological roles because so many other species depend

on them. For the same reason, we should give priority to flagship and umbrella species

that have strategic value to conservation action. People usually favor a species with

realized value over one whose value is only potential because, as the adage goes, “A

bird in the hand is worth two in the bush.” Finally, the uniqueness of a species amplifies

all other values. If we lose a species like the African elephant, its role will not be

easily filled by another species. (See Balmford et al. [1996], Halupka et al. [2003], and

Simianer [2005] for parallel but rather different exercises in selecting, respectively, zoo

collections, salmon stocks, and rare, domestic-animal breeds for conservation.)

374 Part IV The Human Factors

The second question, “Which species is at greater risk of extinction?,” is also a key

issue, especially if you believe that all species have intrinsic value. Intuitively, this

seems to be a simple issue: species that are at greater risk of extinction should receive

higher priority (see Boxes 3.2 and 3.3). However, some conservationists have advocated

a triage approach to dealing with species (McIntyre et al. 1992). Triage refers to

the idea that there are three classes of war casualties: people who will recover without

immediate medical aid; people who will die even if given aid; and people for whom aid

is a life-or-death matter. Priority is given to the third group of casualties, and, similarly,

priority is given to species that have a reasonable chance of surviving if given

attention. Many conservation biologists have difficulty with deliberately abandoning a

species to extinction; surely, the black robin, described in Chapter 13, would have

been lost under a triage system. On the other hand, one could argue that sending four

biologists to Brazil to save the Spix’s macaw, after it was apparently reduced to a single

wild bird, was overreacting to a lost cause (Juniper and Yamashita 1990).

Choosing Nations

International organizations have to decide which countries should receive assistance

with their efforts to conserve biodiversity. Some relevant issues have already

been discussed (e.g. in the hotspots discussion of Chapter 11): notably, determining

Politics and Action 375

Figure 17.1 A consortium of conservation groups called the Alliance for Zero Extinction (Ricketts et al. 2005) has

mapped 595 “centers of imminent extinction,” sites that harbor the only remaining population of highly threatened

species of mammals, birds, reptiles, amphibians, and conifers. Given that just one-third of these sites are

currently protected, they are a high priority for avoiding a wave of extinctions (“open” dots represent sites that

have some degree of protection, whereas the filled dots represent sites with little or no protection). (Map courtesy

of Alliance for Zero Extinction, data version 2.1.)

which countries harbor the most endangered or endemic species or which countries

are in greatest danger of losing their natural ecosystems (see Fig. 17.2 for an example).

Similar processes can be used to prioritize among biogeographic units such as

ecoregions or biomes that reflect species distributions better than political units

(Olson and Dinerstein 1998; Brooks et al. 2004c; Hoekstra et al. 2005). Other

issues have little to do with biology. Which countries have sufficient political stability

to make ambitious conservation projects feasible? Which nations have the

greatest financial need for assistance? Money spent in an unstable country like

376 Part IV The Human Factors

Figure 17.2 Eric Dinerstein and Eric Wikramanayake (1993) used the extent of protected

areas and estimates of deforestation to create an index that would guide international

conservation organizations in setting priorities among 23 Indo-Pacific countries. They

divided the countries into four classes. Category I: countries with a relatively large percentage

(>4%) of forests under formal protection and that will have a high proportion

(>20%) of unprotected forested areas left in ten years. Category II: countries with a relatively

large percentage of forest (>4%) under formal protection, but that will have little

(<20%) unprotected forests left in 10 years. Category III: countries with a relatively low

percentage (<4%) of forests presently protected. However, under current deforestation

rates these countries will still have a relatively large proportion (>20%) of their unprotected

forests remaining in ten years. Category IV: countries with a relatively low proportion

(<4%) of forests presently protected. Obviously, Category IV countries require urgent

action, while Category II and III countries should be shifted toward Category I status

expeditiously.

Rwanda or Columbia is less likely to be effectively used than in a country like Costa

Rica. Conservationists in Swaziland are more likely to need an external subsidy

than those in Sweden. Sometimes, expertise is what is needed. Nations like Saudi

Arabia suffer from a shortage of ecologists, not the money to pay their salaries. One

analysis recommended nations for conservation effort after explicitly incorporating

the estimated cost of creating and maintaining a reserve network covering 15% of

each nation’s area (Balmford et al. 2000). When cost effectiveness was added to the

formula, countries where conservation is relatively expensive moved down the priority

list (e.g. the United States and Australia), while countries such as Peru and

Malaysia rose higher.

Choosing Tasks

Projects designed to maintain biodiversity can often be divided into two broad classes of

activities: protecting ecosystems and species that are threatened versus restoring ecosystems

and species that have been degraded or locally extirpated. Which is more important?

Of course, there is no general answer because so many factors come into play,

but one generalization can be made. It is almost always easier to protect what exists

than to restore what has been lost. Consequently, for a given level of effort, the impact

of a protection project will usually be greater than the impact of a restoration project.

We can also address the issue of choosing tasks by examining the four basic parts of

most complex human undertakings. These are planning (figuring out what we want to

do and how to do it), implementation (doing it), monitoring (figuring out what we have

done and whether it worked), and modification (changing our activity to better achieve

our goals). All of these tasks are critical. Compared with planning and implementation,

most people find monitoring boring, but without monitoring there can be no

effective modification. Vast amounts of conservation effort (translocating endangered

species, restoring degraded ecosystems, etc.) have been wasted because they were not

done correctly the first time and because no one took the time to check the outcome

carefully (Goldsmith 1991; Noss and Cooperrider 1994; Elzinga et al. 2001; Green

et al. 2005a). A recent swell of concern that conservationists have not been adequately

sharing information and learning from one another’s failures and successes

prompted the development of “Open Standards for the Practice of Conservation” now

embraced by most major conservation groups (see Box 17.1).

The Highest Priority of All

Address the causes of problems, not just the symptoms. Many of the activities described

in this book – cross-fostering and double-brooding, maintaining studbooks and seed

banks – only address the symptoms of larger, underlying problems. In particular, the

peril of endangered species is but a symptom of ecosystem degradation and, ultimately,

human overpopulation and excessive consumption (Soule 1991). Of course,

we cannot devote all of our energy to the ultimate problem of human population and

consumption and completely ignore the cascade of symptoms that it produces.

However, we must never lose sight of what is a problem and what is merely a symptom

of that problem. In Lives of a Cell, Lewis Thomas (1974) writes about this issue

from a medical perspective, describing much of medical technology as “halfway

Politics and Action 377

technology” because it addresses symptoms rather than causes. For example, heart

transplant surgery replaces diseased hearts instead of changing the diet and lifestyle

problems that produced the diseased heart. There is an important conservation analogy

here. Protecting entire ecosystems is good public health practice compared with

the emergency-room tactics of ex situ conservation in zoos, aquariums, botanical gardens,

hatcheries, or the intensive management of single species in the wild (see

Chapters 13 and 14) (Fig. 17.3).

378 Part IV The Human Factors

BOX 17.1

Successfully implementing conservation projects

The Conservation Measures Partnership (CMP) was formed when a large group of conservation practitioners met in

2002 with questions and concerns about how to monitor and measure conservation success. There was a prevailing

sense that many organizations were repeating the same mistakes, failing to share lessons learned, and generally

lacking robust ways to measure performance of conservation projects. Donor organizations, which significantly

underwrite the activities of most conservation groups, were particularly interested in evaluating the results of their

investments. In other words, donor groups had few established means to know whether the funds being applied to

conservation were making any difference or which conservation groups or approaches were a better investment. By

forming the CMP, the various member organizations sought to share their experience to avoid duplication of effort,

steer away from failed approaches, and identify and adopt best practices. The most visible product of the CMP has

been a set of standards for designing, implementing, assessing, and auditing conservation projects. The standards

amount to a clear articulation of the adaptive management cycle. As such they bring much needed integrity to conservation

practice by yielding answers to the question: “Do our actions achieve our conservation goals?” Ultimately

the question must be answered in the affirmative if donors and society are to be convinced that conservation is

indeed a worthwhile investment. For further background consult the Conservation Measures Partnership website

(www.conservationmeasures.org).

Figure 17.3 We need to deal with the root causes of the biodiversity crisis. Maintaining

biodiversity by limiting human population growth and wisely caring for entire ecosystems

is much more efficient than saving critically endangered species. It is analogous to saving

lives through public-health programs versus emergency-room surgery.

Rights and Responsibilities

Politics and action depend first on clarifying who has rights and responsibilities for the

well-being of wild creatures. Who owns the giant pandas? Who has the right to use

them and the responsibility to ensure their continued survival? The citizens of China?

Only the people who share the giant pandas’ range in the montane forests of southcentral

China? All the world’s people? Legally speaking, the people of China – formally

the national government of China – own the giant pandas with the exception of the

handful owned by foreign zoos. For other species the answer is not necessarily so simple.

Legal rights and responsibilities can rest with private property owners; with local,

regional, or national governments; with international coalitions of governments (e.g.

in the case of some marine species and migratory birds); or with no one and everyone

(in the case of most marine species that live outside of territorial waters).

In an ideal world rights and responsibilities are shared commensurate with costs

and benefits. For example, the people who live in the forests inhabited by giant pandas

would have the greatest rights and responsibilities per person, but everyone, wherever

they live, would have some rights and responsibilities. In other words, even though

you may live halfway around the world from giant pandas and never see one, you still

have the right to ask for the continued existence of giant pandas and the responsibility

to do what you can to help save them, for example, by giving money to an organization

that supports giant-panda conservation.

Although the rights and responsibilities of people who live far from the pandas’

range are quite small on a per capita basis, collectively they may supersede the rights

and responsibilities of the people who live close by. For example, if the people who

inhabited the giant pandas’ range wanted to allow the panda to become extinct, their

right to make this decision would be superseded by the collective rights of all the

world’s people who want the giant panda to survive.

International Agencies

UNDP, UNEP, UNESCO, IUCN, IMF, ADB: the alphabet soup of organizations that has

evolved to foster better international relationships is large and complex. (See Box 17.2

for brief descriptions of these and other organizations.) In this section we will focus

on some common threads that link these diverse groups to conservation.

1 Fostering a global conservation ethic. All of these organizations have a fundamental

goal of improving the well-being of humanity, but this goal cannot be

achieved without careful stewardship of natural resources. To this end it is important

that the “family of nations” fosters a climate in which its members are encouraged

to practice sound conservation. Various international documents have

codified a global conservation ethic. Among the most important are The World

Conservation Strategy (IUCN et al. 1980), The World Charter for Nature (Annex 2 in

McNeely et al. 1990), the Rio Declaration (Parson et al. 1992; Grubb et al. 1993),

and the “Framework for Action on Biodiversity and Ecosystem Management”

agreed to at the World Summit on Sustainable Development (the so-called

“Johannesburg Summit” of 2002). Although essentially anthropocentric, these

documents suggest some movement toward biocentrism. For example, the World

Charter for Nature, which was passed by the United Nations in 1982, states that

“every life-form is unique, warranting respect regardless of its worth to man.”

Politics and Action 379

380 Part IV The Human Factors

BOX 17.2

International agencies1

United Nations Environment Programme (UNEP, Nairobi) (www.unep.org) facilitates international cooperation

on environmental issues chiefly as a catalyst and source of information. It also administers some funds for environmental

projects, but this is a secondary role. It now oversees the World Conservation Monitoring Centre

(www.unep-wcmc.org).

United Nations Development Programme (UNDP, New York) (www.undp.org) is the world’s largest source

of multilateral grants and funds a wide variety of projects (agriculture, transportation systems, health care, etc.)

with environmental consequences. It also funds projects designed to aid conservation and is a major participant in a

new program, the Global Environmental Facility, along with UNEP and the World Bank.

United Nations Educational Scientific and Cultural Organization (UNESCO, Paris) (www.unesco.org)

facilitates international intellectual endeavors such as improving world literacy. Its mission also includes protecting

the world’s cultural and natural heritage, and it administers the Man and the Biosphere Programme

(www.unesco.org/mab) and the list of World Heritage Sites (see Box 17.3).

United Nations Population Fund (UNFPA, New York) (www.unfpa.org) gathers population statistics and

funds family planning services.

Several other United Nations organizations administer programs that have strong links to conservation issues,

including the Food and Agriculture Organization (FAO, Rome), the World Health Organization (WHO,

Geneva), the World Food Program (Rome), and the United Nations International Children’s Emergency

Fund (UNICEF, New York).

The World Bank (Washington, DC) (www.worldbank.org) is formally known as the International Bank for

Reconstruction and Development, and its goal is to raise the living standards of people in the developing world by

distributing funds provided by wealthier nations. It does this primarily through loans and grants for developing

infrastructure such as roads, dams, electrical systems, and so on. It has often been criticized for the environmental

impacts of its projects, but it is trying to ameliorate these and to initiate conservation projects. There are also

regional development banks: the Asian Development Bank (ADB), the African Development Bank (AFDB),

and the Inter-American Development Bank (IDB).

The International Monetary Fund (IMF, Washington, DC) (www.imf.org) was created simultaneously with

the World Bank, oversees the international system for currency exchange and loans, and negotiates loans itself.

The World Trade Organization (WTO) (www.wto.org) deals with the rules of trade between nations, and its

goal is to help producers of goods and services, exporters, and importers conduct their business. To date its actions

have been widely perceived as harmful to the environment, but it could play a role in removing harmful subsidies

and in negotiating environmental treaties.

The World Conservation Union (www.iucn.org) (formerly the International Union for Conservation of

Nature and Natural Resources and still usually known as the IUCN) is a hybrid organization formed by over 1000

member organizations: governments (chiefly national-level, natural-resource agencies), nongovernmental conservation

groups, and research institutions. Its goal is to promote the protection and sustainable use of living

resources.

1 Information primarily from Welsh and Butorin (1990) and websites.

Unfortunately, the world has yet to live up to the expectations of these documents.

Moreover, one of the most critical elements of a global conservation ethic –

limiting human population growth – is often suppressed in these documents.

Objective analyses based on known ecological constraints suggest that human populations

are already beyond carrying capacity (Wackernagel et al. 2002). For

example, Pimentel et al. (1998) estimate that the populations of North America,

currently some 300 million people, and South America, 500 million, are both projected

to double in about 50 years, yet each continent can support sustainably only

about 200 million people. Why is debate over overpopulation skirted? Some people

fear that population control will infringe on basic human reproductive rights, is an

affront to cultures that value large families, and is a hidden political agenda to suppress

growth of some segments of human society (Seltzer 2002). Others fear that

the discussion of overpopulation turns the spotlight on less-developed countries

rather than on the wealthy countries whose excessive use of resources makes them

equally culpable of causing extinctions (Baltz 1999) (Fig. 17.4).

2 Regulating globally shared resources. Maritime law has regulated human use

of the oceans for centuries – making piracy illegal, for example – and this concept

has been extended to a few treaties that help protect the marine environment, as

well as Antarctica. Unfortunately, a comprehensive treaty for conserving marine

resources, a major goal of the United Nations Law of the Sea Conference, has still

not been completed. More recently, the atmosphere has been recognized as a collective

resource in need of protection. Particular attention has focused on global

warming, and the Kyoto Protocols of The Convention on Climate Change are the

ongoing attempts to cope with the issue (Cameron 2000).

Politics and Action 381

Figure 17.4 Based

on a Miami Herald

cartoon, June

1992. (Reprinted

with special permission

of King

Features Syndicate.)

Recognition of species, genes, and nonmarine ecosystems as common resources

has been more problematic. However, some longstanding treaties do accomplish

the following: (1) protecting natural sites of global significance; (2) conserving

organisms that live outside of territorial boundaries or move among nations (e.g.

whales and migratory birds); and (3) regulating international trade in endangered

species. At the 1992 Earth Summit (officially UNCED, the United Nations

Conference on Environment and Development) in Rio de Janeiro, 153 nations

signed a biodiversity treaty. The “Rio Summit” put forth many grandiose ideas with

good intentions and was followed up by the World Summit on Sustainable

Development (the “Johannesburg Summit”) in 2002, which articulated more concrete

steps forward under its “Framework for Action on Biodiversity and Ecosystem

Management.” See Box 17.3 for the official titles and brief descriptions of some of

the major international environmental treaties.

3 Facilitating the sharing of financial resources. Many international agencies –

notably the United Nations Development Programme, World Bank, and International

Monetary Fund – were designed to allow richer nations to aid the development of

poorer nations through loans or outright donations. In practice, this system has

some major shortcomings (e.g. development projects that do more harm than good,

aid programs that are designed to aid the donor nations more than the recipients,

and exacerbation of the international debt crisis). Despite various problems, a

382 Part IV The Human Factors

BOX 17.3

Environmental treaties1

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

(1973) (www.cites.org) controls international trade in endangered species of plants and animals whether they are

live or dead, whole organisms, or materials derived from organisms. Species listed in their Appendix I cannot be

traded internationally for commercial purposes. International trade in their Appendix II species is regulated and

monitored.

The Convention on the Conservation of Migratory Species of Wild Animals (1979) protects wild animals

that migrate across international borders through international agreements.

The International Convention for the Regulation of Whaling (1946) establishes the International

Whaling Commission (www.ourworld.compuserve.com/homepages/iwcoffice/) to regulate whaling.

The Convention on the Conservation of Antarctic Marine Living Resources (1980) protects the

integrity of the ecosystems surrounding Antarctica and conserves marine living resources there.

The Convention Concerning the Protection of World Cultural and Natural Heritage (1972) establishes

a system of World Heritage Sites that are protected for their natural and cultural values. Another international

system of reserves called Biosphere Reserves has been established by UNESCO’s Man and the Biosphere

Programme to demonstrate the integration of rural development and environmental protection.

The Convention on Wetlands of International Importance, Especially as Water-fowl Habitat (1971)

(often known as the Ramsar Convention because it was signed in Ramsar, Iran) promotes protection of wetland

resources in general and establishes a system of Wetlands of International Importance.

Politics and Action 383

The Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter

(1972) prohibits the ocean dumping of some pollutants and regulates others.

The United Nations Convention on the Law of the Sea (1982) (www.un.org/Depts/los/index.htm) establishes

a comprehensive legal framework for oceans, including regulation of marine pollution and harvesting natural

resources.

The Protocol on Substances that Deplete the Ozone Layer (1987) requires reduction in emissions of

chlorofluorocarbons and halons that deplete the ozone.

The Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water

(1963) prohibits tests that could distribute radioactive debris across international boundaries.

The following five documents were signed by heads of state at the United Nations Conference of Environment

and Development (UNCED) (www.unep.org/unep/partners/un/unced/home.htm) in 1992; the first two are binding

treaties.

The Convention on Biodiversity (www.biodiv.org) This convention’s objectives are “the conservation of biological

diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits arising out

of the utilization of genetic resources.” (This last item has proven contentious, at least in the United States, because

it attempts to establish a mechanism by which nations that are the site of origin for a species or gene would benefit

financially if this species or gene were developed into a marketable product (e.g. a new medicine) in another country.

This treaty has been signed and ratified by 188 nations but not by the United States.)

The Convention on Climate Change (www.unfcc.org) requires stabilization of the concentrations of carbon

dioxide, methane, and other greenhouse gases to avoid interfering with the earth’s climate. The Kyoto Protocol is

the latest manifestation of this convention, but it still has not been ratified (Cameron 2000).

The Statements on Forest Principles. A formal treaty on sustainable management of forests could not be

negotiated, in large part because industrialized nations insisted that it apply only to tropical forests. A nonbinding

statement of 17 principles was signed.

The Rio Declaration promotes general principles to guide nations in their programs for development and

environmental protection.

Agenda 21 describes environmental problems and associated issues such as health and poverty and puts forth

a series of action plans. These cover the legal, technical, financial, and institutional aspects of tackling a host of

problems such as deforestation, desertification, atmospheric pollution, and so on. The difficult part of Agenda 21

was determining how to pay for its estimated cost of $600 billion per year.

The Framework for Action on Biodiversity and Ecosystem Management derived from the World Summit

on Sustainable Development (the Johannesburg Summit 2002) outlines concrete steps toward implementing the

vision outlined in the Rio Declaration.

The Durban Accord: Action Plan resulted from the Fifth World Parks Congress in 2003 and placed protected

areas on the global sustainable development and biodiversity agenda by articulating the following six desired outcomes:

(1) a global system of protected areas linked to surrounding landscapes and seascapes achieved; (2)

improved effectiveness of protected areas management in place; (3) empowerment of indigenous peoples and local

communities achieved; (4) significantly greater support for protected areas from other constituencies agreed;

(5) new forms of governance, recognizing traditional forms of great value for conservation, implemented; and

(6) increased resources for protected areas secured.

1 Information for this box came principally from WRI (1994), Parson et al. (1992), Grubb et al. (1993), and the

listed websites.

system for transferring wealth from richer nations to poorer ones is an essential

part of biodiversity conservation because many of the poorest nations have a vast

array of biota, and it is not fair to expect them to bear the costs of protecting this

global heritage alone. The mechanisms are present to facilitate this process, but the

political will to use them often seems inadequate.

4 Facilitating the sharing of information. Biodiversity conservation is a complex

enterprise that requires vast amounts of information, and international agencies

are uniquely positioned to facilitate this exchange of information through publications,

computerized databases, and conferences. From a biodiversity perspective,

the most important example of such an enterprise is the World Conservation

Monitoring Centre in Cambridge, England, an effort initiated by the World

Conservation Union, the World Wide Fund for Nature, and the United Nations

Environment Programme that is now run as a function of UNEP.

Governments

Governments are powerful. They strongly influence human interaction with most elements

of biodiversity, as well as many key institutions: economics, education, law, and

so on. Ultimate control usually lies with a sovereign nation, but in many cases proximate

control is exercised at a smaller scale by state, provincial, county, or municipal

governments. In some cases there is considerable overlap between national and local

government (Goble et al. 1999; Ray and Ginsberg 1999); for example, having both

national and state laws to protect endangered species may make the safety net of laws

more thorough, or it may lead to inefficient redundancies (Press et al. 1996). In practice,

the actions of governments in protecting biological resources are frequently hobbled

by internal corruption and conservationists need to develop and implement

policies that address corruption’s effects (Smith et al. 2003). In this section we will

review some of the most important ways that governments can shape conservation.

1 Developing and enforcing environmental regulations.Whether by setting a

quota for the number of fish that can be harvested, by compelling car manufacturers

to install air-pollution-control devices, or by prohibiting farmers and homeowners

from wasting water, governments have an enormous, virtually unlimited, scope

to protect the public interest by regulating the activities of private individuals and

organizations. In theory the only limits on what democratic governments can

undertake to conserve biodiversity are constraints imposed by public opinion. In

practice, environmental regulations are often constrained by powerful special interest

groups, especially those that would prefer not to internalize the environmental

costs of doing business. Furthermore, it is much easier to pass laws than to enforce

them.

2 Conserving publicly owned resources. In most countries, virtually all aquatic

ecosystems and many terrestrial ecosystems are publicly owned. In these areas

governments have a particular responsibility to be good stewards because they are

on the front line of natural-resource management, not simply looking over the

shoulder of private property owners and trying to motivate them indirectly to promote

conservation. This responsibility usually takes one of three basic forms: (1)

maintaining a well trained staff of governmental natural-resource managers who

384 Part IV The Human Factors

directly manage publicly owned lands and waters; (2) issuing long-term leases to

individuals and corporations (e.g. selling grazing rights to ranchers) that are

designed to ensure sound conservation; or (3) working with local communities to

conserve natural resources that are legally owned by the national government, but

that are, practically speaking, owned by local communities that have a long tradition

of using the resource. (We will return to communities below.) Additionally, in

most countries wild animals are publicly owned because they can move from property

to property and here, too, governments have special responsibilities.

3 Encouraging conservation through economic policy. Governments profoundly

affect the economics of both individuals and corporations through many

mechanisms. They can offer financial incentives (e.g. direct subsidies, or abatement

of property and income taxes) for activities that contribute to conservation, as well

as financial disincentives (e.g. higher tax rates and fines) for activities that are

harmful (Young et al. 2005). Lowering property taxes for land that is used for conservation

purposes is one of the best examples of an incentive. Another role is promoting

novel economic mechanisms for conservation, such as land use easements

(Merenlender et al. 2004) or “species banking,” in which a property owner agrees

to not develop sensitive lands in exchange for cash from a species bank, which then

collects payments from land owners who wish to develop sensitive land elsewhere,

under government-sanctioned guidelines (Fox and Nino-Murcia 2005).

4 Supporting environmental education and research. Most of the world’s

schools are public institutions; therefore governments assume a major responsibility

for providing students with the education they need to be responsible citizens.

Clearly, this includes education that encourages students to be careful stewards of

the earth. Similarly, most environmental research is undertaken by governmental

agencies and government-funded universities and research institutions; thus governments

have the primary responsibility for filling the information vacuum that

often hampers conservation.

Nongovernmental Organizations

“Nongovernmental organization” (NGO) is a term that covers a broad spectrum of

groups ranging from the World Wide Fund for Nature, with millions of members

throughout the world, to small groups of volunteers that only operate within a single

community, sometimes focusing on a single topic like saving a marsh from being

developed. Many NGOs have no members at all, only a professional staff supported by

grants from foundations, governmental agencies, and corporations. NGOs working on

conservation problems are usually easy to label as “conservation” or “environmental”

groups, but some groups have their major focus on another issue (e.g. labor, health,

indigenous community development, religion) and are involved in conservation

because it is linked with their primary concern.

In a perfect world, there might be little need for NGOs because governments would

be responsive to their citizens’ desires and effective in meeting their needs. In practice,

NGOs have diverse roles to play in the conservation movement. A few are “umbrella”

organizations but most have a particular niche (e.g. fostering a global conservation

ethic, supporting environmental education in a particular region, or research on a

Politics and Action 385

particular taxon). Here, we will consider just two features that are unique to NGOs

and that focus on their interactions with other organizations, especially governments.

1 Representing members to governments and other organizations. People

become members of NGOs because they care, because they support the goals of the

NGO, and because they wish to add their voice to the chorus calling for change.

NGOs give ordinary people a vehicle for communicating with governments, and

sometimes with international agencies and corporations, that are often quite inaccessible

to the average citizen. Writing to elected officials and other powerful people

is important, as we shall see below, but not everyone who cares can attend an official

hearing and give expert testimony. However, along with like-minded people,

they can join an NGO and can be represented by experts. When an NGO staff person

can say: “I represent 400,000 members of the Save the _____ Society,” significant

clout is brought to bear.

2 Using their flexibility to undertake actions that are not open to governments.

Governmental bureaucracies can be rather slow and ponderous because

they are usually large and hobbled by rules designed to limit power and avoid corruption,

so-called “checks and balances.” In contrast, NGOs are nimble, for example,

quickly purchasing a critical ecosystem that is in imminent danger of being

degraded. Moreover, because they are less encumbered by bureaucracy, NGOs can

often undertake the same project at a much lower cost than a governmental

agency. Interestingly, NGOs often work in partnership with governments, for example,

securing and holding land for governments until their bureaucracy can catch

up with the process and assume responsibility. A fundamental part of this flexibility

is the fact that NGOs can use monies obtained from their members and foundations

rather than public tax dollars. Private funds usually have far fewer strings

attached than public funds.

Sometimes, NGOs initiate actions that would be illegal for most governmental agencies:

for example, calling for a boycott of products manufactured by an irresponsible

corporation or, in extreme cases, acts of civil disobedience such as sabotaging a whaling

ship or blocking a road to limit access for oil exploration or unrestrained logging.

Corporations

Corporations usually have a single primary goal – to make money – but most corporate

managers believe that to achieve this goal it is necessary that they be perceived as

“good corporate citizens.” Traditionally, this has meant providing stable, high-salaried

employment, a safe workplace, generous health and retirement benefits, donations to

charitable causes – in other words, being socially responsible. Increasingly, being a

good corporate citizen has come to include being environmentally responsible too

(Daily and Walker 2000). Moreover, many of the resources corporations seek to

capitalize upon can only be secured through cooperative relationships with the communities

controlling them, Consequently some corporations are seeking proactive

relations with local communities and adequate protection of fragile ecosystems

(May et al. 2002).

1 Internalizing the environmental costs of doing business. At a minimum,

this means meeting the standards of environmental regulations; ideally, it means

386 Part IV The Human Factors

exceeding these standards. The greatest disincentive to this – competition in international

markets with corporations that do not internalize environmental costs –

can be solved through international cooperation and trade agreements that “level

the playing field” for these costs.

2 Exceeding the standards of environmental regulations. Some corporations

have learned that it can be profitable to exceed environmental standards. Consumers

are increasingly concerned about the larger impacts of their consumption choices

and prefer to buy products that have been produced in an environmentally sensitive

manner. This phenomenon, often known as green-labeling, first became prominent

with “dolphin-free” labels on cans of tuna fish. It has long been recognized

that good public relations are important to corporate success, and green labels are

a mechanism for codifying the responsible behavior of corporations and conveying

it to the public. Green-labeling involves an independent agency certifying that a

corporation has met or exceeded high standards for responsible behavior (Bennett

2000). Examples are certification programs for “green” coffee (Perfecto et al. 2005)

and forest products (Guynn et al. 2004). It must not be confused with the advertising

many corporations use to promote themselves as good citizens; this is often

based only on the corporation’s image of itself.

3 Finding innovative ways to advance conservation. Some corporations have

found ways to promote conservation that are completely divorced from environmental

regulations (PCEQ 1993). For example, some manufacturers have used

their packaging to carry conservation messages to their consumers. Corporations

that own land can take a proactive approach to conservation, ranging from planting

native plants instead of exotic species on the grounds around a corporate headquarters

to restoring degraded ecosystems and extirpated species on large tracts.

Others make sizable donations to conservation groups whose agendas are consistent

with corporate shareholders or employees. Some do it to enhance their own

image, such as the ExxonMobil Foundation’s significant contributions to the conservation

of tigers, which are also the corporation’s emblem.

Communities

Groups of people who live in the same area, who share common resources, who are

confronted with common problems, or who share common interests can be a very

effective force for conservation (Bernard and Young 1997). This is particularly true in

the rural areas of many developing countries where access to natural resources is

often based on traditional uses rather than on private property rights. In other words,

in these places people’s right to harvest wild plants and animals is based on the fact

that their family has done so for generations, rather than on a legal document giving

them exclusive ownership.

In situations such as this, effective conservation requires empowerment of the communities.

From the governmental side, this begins with recognizing communities’

rights. From the community side, it begins with recognizing the need for cooperation,

both internally and between the community and the government. Once these hurdles

are passed, the process requires sharing control between communities and governmental

officials so that both community interests (e.g. continued access to natural

Politics and Action 387

resources such as firewood and livestock fodder) and national or global interests (e.g.

maintaining biodiversity or minimizing atmospheric pollution) are met. This sharing

of the authority and responsibility of management by different stakeholders has been

called comanagement or participatory management. See Berkes (1989) and West and

Brechin (1991) for more information. Some of the best examples of comanagement

involve fishing, where local fishers have banded together to form cooperatives, and the

government has collaborated with these cooperatives to ensure sound fisheries management

(Acheson et al. 2000; Jentoft 2005).

Individuals

Last and most importantly, there are individuals. All organizations are simply assemblages

of individuals, and all actions begin with one person, one catalyst. The standard

advice for individual conservationists is “Think globally, act locally.” Here are

seven things you can do to follow this advice.

1 Be informed. Read voraciously. Listen attentively. Think critically. Learn your

whole life long (Fig. 17.5). Knowledge confers power. The conservation movement

needs some emotion and subjectivity, but it has an acute need for people with facts

and objectivity. As Patrick Moynahan, a prominent politician, once observed,

“while each of us is entitled to his own opinions, none of us is entitled to his own

388 Part IV The Human Factors

Figure 17.5

Remaining a lifelong

learner is one

of the most important

traits of any

successful conservation

biologist.

These people are

keenly inspecting a

basin full of leaf litter

in hopes of seeing

a small

forest-dwelling

frog, Kihansi

Gorge, southeastern

Tanzania.

(Photo from

J. Gibbs.)

facts.” It is easy to be a “do-gooder”; it is more difficult to be a “good do-er,” someone

who has what it takes to be effective – including knowledge and credibility.

2 Become experienced. Information is not enough; you need wisdom too, and wisdom

comes with experience. Experience can come with age, but there are shortcuts.

Travel is one way. Immerse yourself in another culture, another biota, for a

few months or years. If that is not possible, seek out people from other cultures

who live nearby and talk with them. Try to see the world as they do. By all means

learn another language. Colleges and universities are wonderful places to do all

these things because they are intended to be collegial and universal. Also, travel

where you live; get out and explore your local environment whenever you can. Our

strongest motivations to “change the world” are often rooted in a strong “sense of

place” and devotion to our homeland.

3 Communicate.Write or call your elected representatives, your local newspaper,

corporations, or anyone who is in a position to make a difference, and tell them

what you think. Letters and phone calls make a

huge difference. The environmental movement

was founded in grassroots activism, and its

strength still lies there (Fig. 17.6). Also, do not

limit your communication to distant officials.

Talk to your family, friends, and colleagues

about conservation. Change begins at home.

4 Make your lifestyle consistent with your

values. In other words, do not be a hypocrite:

practice what you preach. This can be difficult.

It is easy to be self-righteous around people

who own big, gas-guzzling sport utility vehicles,

have more than two children, eat lots of

meat, and so on, but are you more virtuous

than those few of your fellow citizens who have

no cars, are 100% vegetarian, live in small

houses heated only with wood that they grow

themselves? Live as frugally as you can and still

be happy. On this note, be aware that overconsumption

in industrialized nations is at the root

of many personal, social, environmental, and

spiritual troubles (Naylor et al. 2001). Last,

make a conscious decision about having children

(see, for example, Hall et al. 1995).

5 Support conservation groups. Many people

are quite generous with their personal monies;

United States citizens alone donated over $185

billion in 2002 to charitable causes (Anft and

Lipman 2003). The lion’s share of these funds

goes to religion (about 35%), health (15%),

and education (13%); conservation groups

Politics and Action 389

Figure 17.6 There are many things you can do as an

individual to “think globally, act locally” like the environmental

educator shown here. Remain informed, gain

experience, learn to communicate effectively, make your

lifestyle consistent with your values, support conservation

groups, and even consider becoming a professional

conservationist. (Photo from D. Andrew Saunders.)

receive less than 5% (as do the arts and humanities). If you think this distribution

is unbalanced, then you should consider directing most or all of your charitable

donations to conservation groups. If you have little money, give your time; most

conservation groups make extensive use of volunteers and interns (in exchange for

valuable experience to you).

6 Become a professional conservationist. Around the world millions of naturalresource

managers, scientists, educators, and the like have dedicated their lives to

conservation. The financial rewards may be modest, but the personal satisfaction

offers substantial compensation. Do it now. Try not to think of yourself as a student

who happens to be majoring in biology, natural-resource management, or whatever;

think of yourself as a professional conservationist who happens to be a student.

In the intellectual hierarchies of colleges and universities, you may feel

unprepared to speak out with authority. However, having successfully read this far

in the book you already are something of an authority on biodiversity conservation

and very much so relative to the general public’s knowledge on the topic. Join a

professional society such as the Society for Conservation Biology and attend its

meetings. Many professional societies have local and student chapters. Seek out a

mentor and ask that person lots of questions.

7 Keep your perspective. It is easy to get depressed when contemplating the magnitude

of the biodiversity crisis and when evaluating your chances of making a

measurable difference. To avoid this, keep your perspective focused on an appropriate

temporal and spatial scale. Make life better where you live, in your lifetime.

Also, take heart that there have been some miraculous success stories in conservation

that originated through the actions of individuals like you. Chico Mendes,

Rachel Carson, John Muir, Wangari Mathai, and many others had very humble origins,

but accomplished great things for wild creatures.

Summary

Conservation action begins with individuals, and there is much that you can do to assist with

efforts to maintain biodiversity. First you must recognize the limitations on resources for conservation

work and prioritize actions. Efficiency often dictates that we focus on large-scale entities

(ecosystems rather than species or genes), especially those that are at risk at a global scale.

Choosing specific sites for conservation management involves weighing multiple criteria such

as size, representativeness, rarity, condition, and feasibility. In choosing tasks, we must be careful

not to focus solely on planning and implementing conservation action and, thereby, neglect

the monitoring that can lead to modifications of our actions. Finally, the overriding priority is

to try to deal with the root causes of biodiversity loss, rather than the symptoms, mainly

human overpopulation and excessive consumption. Once priorities have been set, politics and

action requires working with other people in the context of various types of institutions: international

and governmental agencies, conservation groups and other nongovernmental organizations,

local communities, and corporations. Each of these has a special role to play in the

conservation movement. Ultimately, every person has the right to enjoy the manifold benefits of

biodiversity and with that right comes the responsibility to work to maintain biodiversity. This

work must go forward within the fabric of social, economic, and political realities.

390 Part IV The Human Factors

FURTHER READING

Book length treatments of conservation priorities include Usher (1986), Spellerberg (1992), and Johnson (1995)

(available on the web at www.worldwildlife.org/bsp/). An internet search on “conservation priorities” will generate

scores of websites where various conservation organizations describe their priorities for action. The “Framework for

Action on Biodiversity and Ecosystem Management” derived from the 2002 Johannesburg Summit gives substantial

insight into concrete steps toward implementing global approaches to conservation (see www.johannesburgsummit.

org). The Conservation Measures Partnership (www.conservationmeasures.org) is a key resource for bringing

standard practice to conservation programs. Similarly, the Alliance for Zero Extinction is a global consortium of

conservation organizations that seeks to prevent extinctions by identifying and safeguarding key sites for biodiversity

(www.zeroextinction.org). For activities directly relevant to college campuses and conservation students, see

Marzluff (2002), Wellnitz et al. (2002), and Inouye and Dietz (2000). World Resources 2002–2004 and its periodic

revisions (United Nations Development Programme et al. 2003) are important compendia of information on which

to base action. For popular accounts of biodiversity to share with people, see Grumbine (1992) and Wilson (1992).

Schaller (1993) gives a good account of the politics that have surrounded giant panda conservation. Mulder and

Coppolillo (2005) provide a particularly lucid presentation of the linkages between biodiversity, politics, economics,

and culture. Many journals carry articles related to conservation biology; the two most important are Conservation

Biology and Biological Conservation. URLs for the websites of major international agencies and certain treaties are

given in Boxes 17.2 and 17.3.

TOPICS FOR DISCUSSION

1 If you had to choose between purchasing 1000 ha of mature forest to establish a reserve or buying 2500 ha of

recently cut forest for the same price, which would you choose? Assume that the mature forest was partially cut

forty years ago and that the recently cut forest received a similar cut (about half the mature trees removed) two

years ago.

2 How does the motto “Think globally, act locally” square with the idea that priorities for conservation action

should be at a global scale? What should conservationists who live in a low priority region do?

3 If you believe that all species have intrinsic value should you consider any other issues besides risk of extinction

when deciding which species should be a high priority for conservation action?

4 If everybody made the same personal choices as you, would there be a biodiversity crisis on earth?

5 Do you think corporations that undertake environmental activities are sincere or driven by public relations

concerns? Do their motivations matter?

6 How would natural-resource management in your area be different if policies were determined entirely by local

communities without influence from state and national governments?

7 What species or ecosystems are threatened in your area? What can you do to help them?

8 Identify one obstacle that hinders you from taking political action. How can you overcome it?

9 How can the different entities described in this chapter work together more effectively?

Politics and Action 391

e eBook Collection

Have you ever had a window seat on a plane on a clear day? If so, you probably saw

landscapes dominated by the hand of humanity, roads and power lines stretching to

the horizon, etched across a mosaic of cities, towns, and farms. You may have also

seen the dark green of extensive forests or the blue of lakes or ocean, especially as you

flew farther from the airport. However, you are not likely to have seen many reserves,

for they constitute a tiny fraction of most landscapes. Fortunately, the good news is

that a multitude of species thrive, or at least survive, outside of reserves, sharing lands

and waters with loggers, fishers, farmers, ranchers, etc. The opportunities for pursuing

biodiversity conservation while meeting the needs of people are particularly great in

seminatural ecosystems – ecosystems that have been modified by human activities

such as logging, fishing, and grazing livestock, but that are still dominated by native

species. Methods for integrating biodiversity maintenance with natural resource management

in these modified ecosystems constitute the first section of this chapter. The

second and third sections deal with cultivated ecosystems (largely agricultural land)

and built ecosystems (urban areas and other places intensively used by people), where

a surprising number of species can survive under careful management. We also need

to keep these ecosystems from exporting problems such as invasive exotics and contaminants

to natural and seminatural ecosystems. In the final section of this chapter

we will delve into restoration ecology, a discipline that focuses on methods for restoring

the structure and function of ecosystems degraded by human activities.

Modified Ecosystems

It is likely that an astute observer could detect human-induced modifications in all the

world’s ecosystems. Some we have modified beyond recognition; in others, perhaps deepocean

bottoms, it would be fairly difficult to detect our influence. In this section we will

focus on just a narrow set of modifications, those that modify ecosystems through management

for three commodities – wood, livestock, and fish – but still leave the ecosystem

in a seminatural condition. These activities present important opportunities for conservation

biologists to work collaboratively with their fellow natural resource managers, especially

foresters, range managers, and fisheries managers. They offer vast expanses of land

and water because most of the earth’s terrestrial ecosystems and virtually all of its

aquatic ecosystems are seminatural ecosystems open to natural resource utilization. To

ignore these areas would be extremely shortsighted (Fig. 12.1). They may never be pristine

ecosystems, but they can support a multitude of species, including some species that

CHAPTER 12

Managing Ecosystems

are often deemed highly sensitive

to human activities, such as

wolves and grizzly bears (Musiani

and Paquet 2004).

Forestry

Three facts from Chapter 8 bear

repeating here: forests cover less

than 6% of the earth’s total surface

area; forests are habitat for

a majority of the earth’s known

species; forests are being lost far

faster than they are expanding.

Let us add a fourth fact: most

forests are not in reserves; they

are available for logging and

other uses. This fact brings both

good news and bad. The bad

news is that logging can seriously

threaten biodiversity in

those areas that remain

forested. The good news is that

logging does not have to be a

serious threat, and that forests

that are producing a valuable

commodity are less likely to be

eradicated to make way for other land uses, such as agriculture or urban areas.

Here are three ideas for integrating forest management and maintenance of biodiversity

extracted from two books on the subject (Hunter 1990, 1999).

Age Structure

It is difficult for people, with a life span measured in decades, to fully appreciate the

life and death of trees whose lives span centuries, sometimes millennia. Yet trees do

die, of course. In some forests, trees tend to die a few at a time, leaving small holes in

the forest canopy in which young trees can grow. These forests will have trees of several

different ages, and they are called uneven-aged. Other forests are even-aged

because most of the trees originated after some disturbance event (e.g. a crown fire or

clearcut) killed most of the previous generation.

Age structure is a critical issue because the biota of an old, even-aged forest is

not the same as the biota of a young, even-aged forest (Fig. 12.2). Even at the scale of

an individual tree, an old tree provides habitat for a different set of species than a

young tree. Consequently, maintenance of biodiversity requires having a balanced

age-class distribution. This means having (1) uneven-aged forests (in places where

trees usually die a few at a time), (2) landscapes with many different even-aged

forests – some young, some middle-aged, some old – (in places where large-scale

Managing Ecosystems 253

Figure 12.1 Conservationists cannot afford to adopt a siege mentality,

protecting reserves and ignoring the rest of the landscape. (The idea for

this figure was shared by Eduardo Santana, but its originator is unknown.)

disturbances typically initiate succession on a large area), or (3)

some combination of these two (in some landscapes large-scale disturbances

produce even-aged forests at intervals of several hundred

or even thousands of years, but most of the time small-scale disturbances

are predominant [Seymour et al. 2002]). Having a balanced

age-class distribution is also essential to meet a major goal of timber

managers: producing a continuous supply of wood. Unfortunately,

this is not the end of the story.

A conflict arises between maintaining biodiversity and timber production

because trees usually grow to an optimal size for cutting

long before they die of natural causes. This means that old trees and

old forests are uncommon, or even absent, in most areas managed

for timber production. The most famous example of this conflict

comes from the North American Pacific Northwest, where the

remaining, old-growth, Douglas fir forests are both critical habitat

for the spotted owl and many other species, and a commodity of

great value to the timber industry.

There is another dimension to forest age structure. When a tree

eventually dies, it continues to have ecological value because a

unique and very diverse set of species is dependent on dead and

dying trees (McComb and Lindenmayer 1999). These range from

woodpeckers and the broad array of other vertebrates that use tree

cavities to the myriad of invertebrates, fungi, and bacteria that

reduce deadwood to its organic constituents. Furthermore, in many

forests fallen trees are “nurse logs” for another generation of trees

because they provide nutrients and moisture for seedlings. Few trees

die and are left to rot if a forest is being managed for maximum timber

production, and this can be a major problem for all the species

dependent on this unique microhabitat.

The conflict between the need for timber production and the

need for old and dead trees can be resolved, or at least diminished,

by allowing some trees to age and die. This can take place on

many scales. At the smallest scale, it means identifying some individual

trees that will be allowed to grow old and die. This is simple

when trees are individually selected for cutting; it is more difficult,

but still possible, to retain some large old trees in clearcuts

(Franklin et al. 2002). At an intermediate scale, forest ecologists

often advocate setting aside small patches of trees (e.g. a quarterhectare

patch on every 10 hectares of forest), or uncut riparian

zones that offer two other benefits: protection of aquatic ecosystems

and travel corridors. Finally, at the largest scale, forgoing logging

on entire forests and landscapes returns us to the preceding

chapter on protected ecosystems.

Forest managers can also defer cutting until the trees are larger

and thus allow them to provide habitat for old-forest species for a

longer time: for example, cutting an even-aged forest when it is

125 years old rather than 80 years old. Silvicultural techniques

254 Part III Maintaining Biodiversity

Figure 12.2 The assemblage of

species associated with a forest

changes as the forest undergoes a

cycle of succession and disturbance.

Even a single old tree will support a

different biota than a small tree,

perhaps because it is taller or its

bark more fissured. (From Hunter

1990, reprinted by permission of

Prentice-Hall, Englewood Cliffs,

New Jersey.)

for stimulating trees to grow bigger (e.g. thinning) can be useful because organisms

are attuned to the size of a tree rather than its actual age. Of course, growing

bigger trees does nothing for all the species that need dead trees if the trees are still

cut before dying. Forest managers have sometimes remedied a shortage of dead

trees by killing live trees, but this is only a short-term solution.

Spatial Patterns

When mature trees die, they leave an opening that can range in size from the

canopy gap left by a single windthrown tree, to many thousands of hectares in

the case of boreal forest fires (Spies and Turner 1999). Similarly, the scale of logging

operations can range from cutting single trees scattered throughout a forest

to clearcutting large swathes. Many conservationists favor small-scale cutting

because removing single trees distributed over a large area seems much less disruptive

than cutting all the trees in one place. However, most forest ecologists would

argue that it is more important to match the scale of cutting to the scale of natural

disturbances. This would mean cutting individual trees in all-aged forests where

trees die one at a time, but it would also mean cutting tracts of even-aged forest in

blocks that match the sizes of the natural disturbances that initiate succession

(Hunter 1993).

The following hypothetical scenario will make this difference clearer. Imagine an

isolated village in which wood is the only source of fuel and the villagers need to cut

1000 trees each year. Near the village is a 1000 ha forest that has 100,000 mature

trees and (to keep things simple) the villagers have three choices: (1) cut one tree from

each hectare; (2) cut all 1000 trees in a single clearcut of 10 ha, or (3) cut ten 1 ha

patches each containing 100 trees. Option 1 would have the least impact in the short

term and thus be favored by many conservationists. However, what if this type of forest

routinely experiences large-scale natural disturbances, and the trees in this forest

are only able to regenerate in openings larger than the size of a single tree crown?

(This is true of many tree species that live in even-aged forests; they are called shadeintolerant.)

In this case many conservationists would propose option 3, ten small

patch cuts. However, if you recall Figs 8.14 and 8.15, you will realize that option 3

would fragment the forest more than option 2, especially if you needed a road network

to access all the cuts. Ideally you would determine whether option 2 or 3 was a

better match for the natural disturbance regime and, in the absence of precise information,

perhaps you would use a mixed strategy, cutting ten small patches one year

then one large one the next year.

This scenario was constructed to show that the obvious solution is not necessarily

the right one; small-scale cutting is not always preferable to large-scale cutting. This

said, conservationists’ concerns about clearcutting are usually well founded. There

are many forests that are being clearcut because it is the most expedient way to

remove trees even though it bears no resemblance to a natural disturbance regime. It

is far harder to find forests that should be subject to large-scale disturbances, but that

are being logged with small cuts. Furthermore, unless sensitively undertaken,

clearcuts may have little resemblance to fires and windthrows, in particular because

these natural disturbances usually leave significant numbers of live and dead trees in

their wake (Keeton and Franklin 2005).

Managing Ecosystems 255

Species Composition

Some tree species are more profitable to grow and cut than others: for example, some

are so valuable that a single tree is worth tens of thousands of dollars; some can grow

over 10 meters in five years. These differences encourage foresters to try to control

the species composition of a site by planting seeds or seedlings of desirable species or

controlling undesirable species (e.g. through thinning or herbicides). Not surprisingly,

these manipulations can have negative consequences for the forest’s other biota. To take

a simple example, all the species dependent on acorns will suffer if a forest’s oaks are

replaced by pines. The effect is likely to be considerably greater if the planted trees are

exotics: plantations of Australian eucalyptus trees are found on every continent except

Antarctica, and many of these plantations have impoverished floras and faunas.

From a biodiversity standpoint the solution is simple. Foresters should favor the tree

species that are native to a particular forest. Techniques for controlling species composition

also allow foresters to shift the species compositions of forests that have been altered

by previous management toward their natural composition (Palik and Engstrom 1999).

Livestock Grazing

We are all familiar with the image of cattle grazing on an open plain, but many other

species are used as livestock, and they forage in a diverse array of uncultivated terrestrial

ecosystems, collectively called rangeland, that cover about 25% of the earth’s

land surface (Asner et al. 2004). This section is relevant in some degree to sheep,

yaks, and llamas on alpine meadows; reindeer on the tundra of Lapland; dromedaries

and goats in the deserts of the Middle East; and the various species that are grazed in

woodlands (i.e. forests open enough to have a well developed stratum of ground vegetation).

This said, however, we will focus primarily on grasslands and cows.

Compared with forests, grasslands have been given less attention by conservation

biologists, and, consequently, we have a more limited understanding of what livestock

grazing does to them and how to manage them for biodiversity (Noss and Cooperrider

1994; Tainton 1999). Nevertheless, some ideas seem intrinsically obvious because

they are based on the logical premise that rangeland management will be more

compatible with biodiversity if it maintains ecosystems that are somewhat similar to

natural ecosystems.

Native Grazers

One obvious tactic is to use species of livestock that are as close as possible to the species

that are native to a particular ecosystem. For example, consider the evolutionaryecological

relationships of the cow, which is thought to have been domesticated from

aurochs, a largely forest-dwelling bovine from Eurasia that became extinct in the seventeenth

century (Clutton-Brock 1981). Cattle are clearly more at home in Eurasia than

in Australia, where kangaroos and other marsupials were the only large mammalian

grazers for at least 20 million years. In North America some people have argued that

cattle are a reasonable substitute for American bison (buffalo) because they are fairly

close relatives. No doubt they are a better substitute for bison than are goats or sheep,

and grazing by cattle may well be preferable to no grazing by large mammals at all

(Milchunas et al. 1998). For example, one study found that plant species richness was

256 Part III Maintaining Biodiversity

greater on plots grazed by bison or cattle than ungrazed plots because the grazers created

a patchwork of different degrees of grazing pressure (Towne et al. 2005). However,

there are some differences between cattle and bison; notably, cattle need access to water

and shade more than bison do, and thus in semiarid landscapes they concentrate in

riparian zones, where they often overgraze the vegetation (Fig. 12.3).

To a limited extent this pattern of favoring natives exists already: Asian elephants,

reindeer, Bactrian camels, dromedaries, llamas, alpacas, yaks, and water buffalo are

all used primarily within their native ranges. Moreover, there is a growing interest in

game ranching or farming, i.e. raising undomesticated large mammals such as bison

in North America, or eland in Africa within fenced areas (Teer et al. 1993).

Finally, human desire for meat could be met by game cropping: the systematic and,

it is hoped, sustainable harvest of wild (neither domesticated nor captive) larger mammals,

birds, and reptiles (Hudson et al. 1989; Robinson and Bennett 2004). Game

cropping is not livestock management, but it can involve managing rangelands

(e.g. by providing water holes) and thus fits within this section.

Natural Grazing Patterns

Another tactic is to use the spatial and temporal patterns of native grazers as a model

for livestock grazing systems. For example, many native grazers visit an area for a

short time, graze it intensively, and then do not return for a year or longer

(McNaughton 1993). In contrast, livestock is often allowed to graze an area continuously

as long as there is some food and water. When livestock managers do rotate

herds among different areas, the emphasis is usually on providing the livestock with

more forage rather than on maintaining a seminatural ecosystem (Holechek et al.

2003). It is particularly important to control the spatial distribution of livestock

Managing Ecosystems 257

Figure 12.3 The

grazing effects of

cattle may be analogous

to those of

wild ungulates but

there are differences.

For example,

cattle are even

more dependent on

riparian zones than

are bison. (Photo

from R. Robinson,

provided by

Yellowstone

National Park.)

because they tend to gravitate toward and overgraze precisely those places that are

most important to the native biota, the relatively uncommon spots with ample water

and the most fertile soil. Livestock abundance also needs to be tightly controlled

because populations of native herbivores are likely to be relatively low compared with

livestock (Towne et al. 2005).

The key issue is to avoid overtaxing the plants’ ability to grow and reproduce

because overgrazing can profoundly change the vegetation and thus the entire biota.

Moreover, once these changes have occurred, simply removing the livestock will not

necessarily lead to the restoration of the original vegetation, especially if overgrazing

has led to desertification or the encroachment of woody shrubs (Asner et al. 2004).

Overgrazing can be difficult to assess because one of the most critical processes happens

underground, where perennial grasses and forbs (vascular plants that are neither

woody nor grasslike) must replenish their carbohydrate reserves during each

growing season. If grazing curtails this process too much, these plants will be

replaced by other species that are less vulnerable to overgrazing, either because they

are less palatable to grazers, or because they are more tolerant of being grazed.

Natural Disturbance Regimes

Like forests, grasslands are shaped by natural disturbance regimes such as fires,

floods, droughts, and tornadoes. Fire is the most important of these on most rangelands,

and ecologically sensitive range management must provide for the continuation

of a natural fire regime, although what constitutes a “natural” fire regime can be

controversial given the ancient history of humans setting fires (Bond and Keeley

2005; Bond et al. 2005). In many grassland and shrubland ecosystems, if fire does

not occur quite frequently, trees will invade and transform the site into a woodland or

forest ecosystem. The similarity and differences among grassland fires, grazing, and

mowing is a complex topic that can prove quite controversial when managers propose

substituting one for another (Collins et al. 1998; Swengel 1998; Panzer 2002). For

example, in Europe it has been suggested that the current rarity of natural fires and

native large herbivores means that livestock grazing or mowing is needed to maintain

habitat for many open-land species (Pykala 2000, 2005).

Predators and Competitors

The interests of range managers and conservation biologists collide directly over one

issue in particular, predator control (Freilich et al. 2003). Livestock owners are understandably

reluctant to share their valuable stock with wolves, snow leopards, cheetahs,

and other predators, while, on the other hand, these same predators are flagship

species around which conservationists rally. Fortunately, livestock managers can, if

they wish, minimize the loss of livestock without decimating entire predator populations:

for example, by using guard dogs and selectively removing individual predators

that have developed a taste for livestock (Marker et al. 2005).

An analogous problem can arise whenever livestock managers feel that native

herbivores are competing for scarce forage. Programs to control prairie dogs in

North America are a particularly egregious example of this because prairie dogs play

keystone roles in grassland ecosystems through their extensive burrowing activity

258 Part III Maintaining Biodiversity

(Miller et al. 2000), and some evidence suggests that they do not affect habitat selection

or grazing rates of cattle anyway (Guenther and Detling 2003).

Range Management Techniques

Range managers have a sizable repertoire of management tools that are likely to produce

results that are contrary to the well-being of wild life (Holechek et al. 2003).

Unwanted vegetation is often removed by dragging a chain between two vehicles, or

spraying with herbicides. Exotic species, especially grasses believed to be more palatable

or less vulnerable to overgrazing, are introduced. Fences are erected to control

the movement of livestock and sometimes wild animals. Water holes are dug and can

become a focal point of overgrazing. It is important to remember that these are just

tools and that they can be used for positive purposes as well. For example, fences may

be necessary to keep livestock out of sensitive riparian zones or from spreading diseases

to wild animals. Vegetation control may be the first step in restoring a degraded

grassland that has been invaded by shrubs.

Fisheries

Like eating grass in a grassland, catching fish in an aquatic ecosystem may seem like

a fairly benign activity, but appearances can be deceptive. As we saw in Chapter 9 and

the Gulf of Maine case study, fishing can profoundly modify aquatic ecosystems, particularly

because many exploited species have pivotal ecological roles as dominant or

keystone species. In this section we will examine how fisheries management in seminatural

aquatic ecosystems may affect aquatic biodiversity. This topic has received relatively

little attention (Wilcove and Bean 1994; Kohler and Hubert 1999), and thus

some of the ideas presented here are somewhat speculative.

The oceans, lakes, rivers, and other aquatic ecosystems that support fishing are

usually publicly owned, and thus a large portion of fisheries management consists of

government agencies managing the people who catch fish, both commercially and

recreationally (Fig. 12.4). This means regulating when, where, and how fish are

caught, and especially how many fish of what species and sizes. (To keep things simple

we will refer just to fish in this section, but the basic principles apply to many other

aquatic organisms exploited by people, such as shrimp, mollusks, lobsters, and various

seaweeds.) The traditional goal of most fisheries managers is usually fairly simple:

optimize the sustainable production of desirable fish species. This usually means

maintaining populations of these fishes at fairly high levels, at least half of what they

would be in a natural, unexploited ecosystem. Therefore, in theory, sustainable fisheries

management could be reasonably consistent with biodiversity conservation as

long as management does not focus too narrowly on the species targeted for harvest.

Unfortunately, this is not the end of the story. Fisheries managers are often

unable to achieve sustainability because they cannot adequately regulate fishing,

as described in Chapter 9. Not only are total catches unsustainable, but the impact

on particular fish species, especially those high in the food chain, has been catastrophic

(Mullon et al. 2005; Pauly et al. 2005). The difficulty in restricting fishing

is due in part to an inherent mismatch between fishing by people and the natural

mortality patterns of fish (see Fig. 9.9). Furthermore, regulating fishing is not

Managing Ecosystems 259

enough; fisheries managers must also be vocal opponents of water pollution, loss of

wetlands, dam construction, and other factors that generally degrade the environment

for fish. In short, managing aquatic ecosystems for biodiversity is usually in

tune with the major efforts of fisheries managers. Their lack of success at stemming

the tide of overexploitation and environmental degradation may be dismaying, but

at least they are trying.

Although the objectives of fisheries managers are in concert with the

objectives of conservation biologists much of the time, there are important exceptions

(Wilcove et al. 1992). Exotic species provide the most obvious example. From the perspective

of a fisheries manager trying to produce large catches of desirable fishes,

introducing new species to a water body has long been an acceptable practice. From a

biodiversity perspective these exotics are an anathema (Chapter 10). Similarly, fisheries

managers sometimes try to reduce populations of native, undesirable species –

“trash fish” – that compete with preferred species. In its most extreme form this can

involve poisoning a lake or river to kill the native fish and then replacing them with

desirable species; recall what happened on the Green River (Chapter 10; Holden

1991). Fortunately, most fisheries managers are now better attuned to the value of all

aquatic organisms and no longer use the term “trash fish,” at least in polite company

(Wydoski and Wiley 1999). Conservation biologists also need to evaluate fisheries

management techniques that involve modifying the natural physical or chemical

environment of aquatic ecosystems: for example, manipulating water levels, building

artificial structures to serve as spawning areas or cover, and adding fertilizer to

increase primary production (Kohler and Hubert 1999). The scale and impact of

these modifications are usually quite limited, but in some cases they might have a

deleterious effect on biodiversity by altering the habitat of a rare species.

260 Part III Maintaining Biodiversity

Figure 12.4

Regulating fishing

is the primary way

that fisheries managers

control

aquatic ecosystems.

Here a fisheries

observer measures

the size of commercial

fishing

nets. (Photo from

the Alaska Fisheries

Science Center.)

The bottom line is that as long as fisheries managers are attempting to maintain or

restore populations of native fishes and their ecosystems, their activities can be

endorsed by biodiversity advocates. Sometimes, zealous fisheries managers will initiate

something that is likely to degrade biodiversity such as introducing an exotic fish,

but this is becoming less common. Unfortunately, the actual track record for maintaining

healthy seminatural aquatic ecosystems is poor, which highlights the need for

many more aquatic reserves closed to fishing (Norse and Crowder 2005).

Extractive Reserves

The term “extractive reserve” may seem like one of those oxymorons: “soft rock” or

“bureaucratic efficiency.” It is most commonly associated with areas in the Amazon

Basin that have been protected from intrusive forms of land use such as large-scale

agriculture or commercial logging, but that are still open for limited extraction of

resources: for example, collecting nuts and fruits and, especially, tapping rubber trees

(Fearnside 1989; Salafsky et al. 1993; Ruiz-Perez et al. 2005). This basic idea could be

applied anywhere. For example, if a large area of the Arctic were declared off limits to

oil extraction and commercial fisheries, but were still open to native people for subsistence

hunting and fishing, this area could be called an extractive reserve. The primary

difference between an extractive reserve and a traditional reserve that allows some

extraction (e.g. Nepal’s Chitwan National Park, described in Chapter 11) lies in

their goals. An extractive reserve would put production of natural resources for local

people first, and protection of the ecosystem would be a second, although still very

important, goal. A traditional reserve would put ecosystem protection first.

Ecological Management

The take-home message from this section can be summarized easily: to integrate natural

resource management and maintenance of biodiversity, ecosystems should be

managed in a way that is as consistent with natural ecological processes as possible.

In other words, sustainable exploitation of ecosystems will be most successful if

approaches are used that mimic established ecological relationships rather than introduce

novel ones: for example, cut trees in a manner that imitates natural disturbances;

graze livestock so that they are a surrogate for native herbivores. In other

words, use natural ecosystems as a model, a point of departure (Angermeier 2000).

Too often managers of these ecosystems use agriculture as a model, and that is

fraught with difficulties, as we will see in the next section.

Cultivated Ecosystems

Across great sweeps of the earth, the land is a vibrant green testament to

photosynthesis, yet the variety and abundance of wild life are only a shadow of what

they should be. These are our cultivated lands, the places where we have replaced

natural ecosystems with a sparse assemblage of exotic and native species. Row crops

of grains and vegetables are the dominant form of cultivated ecosystem, but we have

created many other types of ecosystems to produce food, fiber, or fuel. These include

orchards, tree plantations, ponds devoted to aquaculture, cranberry bogs, cattail

Managing Ecosystems 261

marshes managed for biomass fuel, and more. Admittedly, drawing a line between a

cultivated ecosystem and an intensively managed seminatural ecosystem can be a

rather arbitrary decision. A pasture sown with seeds of an exotic grass species and

then carefully fertilized and grazed is clearly cultivated, but what if the sown grass

were a native species? How do we separate tree plantations and intensively managed

forests?

The process of turning natural and seminatural ecosystems into cultivated ones is

probably the most important proximate cause of biodiversity loss, the ultimate causes

being the burgeoning human population and our demand for the products of all these

cultivated ecosystems. Consequently, conservationists routinely object to the expansion

of cultivated ecosystems. Beyond this, however, they tend to ignore these places

as blank spots on the map of biodiversity, and thus they do not interact much with

farmers (here broadly defined to include fish farmers, tree farmers, etc.) except in

regions where farms completely dominate the landscape. This is shortsighted for two

reasons that we will examine further: (1) with careful management, some important

elements of biodiversity can persist in a cultivated ecosystem; and (2) thoughtful

stewardship of cultivated ecosystems can ameliorate their negative effects on

surrounding landscapes and minimize their rate of expansion.

262 Part III Maintaining Biodiversity

Figure 12.5 Whether it is a stone-wall lined pasture in New England or a hillside in

Nepal carved into terraces, a key factor in maintaining biodiversity in agricultural landscapes

is maintaining patches of native vegetation, especially along streams and lakes.

(Photos from M. Hunter.)

Biodiversity in Cultivated Ecosystems

If farmers had total control of their ecosystems, many of them would channel virtually

all the resources of a site – energy, water, nutrients – into crop species and a

handful of key associates such as nitrifying bacteria and pollinating insects. Witness

farmers’ efforts to control unwanted species – weeds, pests, vermin. Fortunately for

biodiversity, most farmers fall far short of this goal, and some do not pursue it assiduously

because they enjoy sharing their land with other species.

The single most important factor allowing wild life to persist in a cultivated setting is

the tiny relicts of habitat that receive little or no cultivation (Carroll et al. 1990). These

would include a strip of shrubs along a ditch, a patch of trees on a rocky outcrop in the

middle of a hayfield, a wet spot in the midst of a plantation, a hedgerow separating two

fields, and similar places (Fig. 12.5). They are too small to be managed as independent

Managing Ecosystems 263

Figure 12.5 Contd.

ecosystems, but are large enough to provide refuge to a surprising diversity of wild creatures

(Miller and Cale 2000; Duelli and Obrist 2003). Therefore, one of the most important

things a farmer can do for biodiversity is to retain these places or even restore and

expand them. For example, farmers in Europe and elsewhere need to retain hedgerows

even though with modern machinery it is now easier to cultivate one large field than

two smaller ones (Dowdeswell 1987; Baudry et al. 2000). Prairie farmers in North

America need to resist the temptation to fill or drain the small potholes that support

pintails, avocets, and a large array of other wetland species (Mitsch and Gosselink

2000). Some farmers will actively create these environments; farm ponds are the most

common example of this (Knutson et al. 2004). In Europe habitat for uncommon

plants and insects is created by maintaining 2–12 meter-wide strips at the edges of

fields that are managed differently from the crops perhaps not sprayed with pesticides

or fertilizers, perhaps not tilled (Critchley et al. 2004; Field et al. 2005). Decisions to set

aside some land to lie fallow for one or more years, resting before another commercial

crop is grown, also creates these patches of natural, albeit on a short-term, always

shifting basis (Firbank et al. 2003). Conservation that focuses on small features of the

landscape such as hedgerows and riparians strips has been termed “mesofilter” conservation

because it operates at a scale between the ecosystems of coarse filters and the

single species focus of fine filters (Hunter 2005).

Natural remnants are not the whole story in agricultural landscapes; the variety of

commodities being grown also contribute to landscape diversity (Chamberlain et al.

2000; Wilson et al. 2005a). Not surprisingly, dairy farmers who maintain pastures,

hayfields, and feed-corn cropland, and who supplement their income with a small

orchard, are providing habitat for far more species than farmers who grow nothing

but soybeans. Unfortunately, the overall trend has been toward greater specialization.

This is particularly noticeable among farmers of developing countries as they shift

from an emphasis on subsistence agriculture – growing a diversity of crops to meet

most of their personal needs – toward an emphasis on growing cash crops (Donald

2004; Gray 2005). The difference between coffee grown under the shade of various

trees that provide fruit and firewood and coffee grown in the open is one example of

this phenomenon (Tejeda-Cruz and Sutherland 2004). The shade coffee supports a

much larger native biota and can provide a wider variety of products for the farmer,

but commercialization favors sun coffee. A growing movement to make agriculture

more ecologically sound (associated with terms such as sustainable agriculture, agrienvironment,

alternative agriculture, or agroecology) emphasizes using a diversity of

crops, including trees, but it remains to be seen if the overall trend toward specialization

will be reversed (for more information on this movement, see Carroll et al. 1990;

Collins and Qualset 1999; Kleijn and Sutherland 2003; Firbank 2005).

The specific practices farmers employ to cultivate their farms can also have a dramatic

effect on wild life (Bengtsson et al. 2005). Use of insecticides, herbicides, fungicides,

and other types of pesticides is probably the most important example because

they are so commonly used and because their effects on targeted and nontargeted

species, both on and off the sprayed site, can be so severe (see the section on pesticides

in Chapter 8). Suffice it to say here that farmers who are concerned about biodiversity

will minimize their use of these chemicals (Beecher et al. 2002; Hole et al. 2005). One

practice that can rivet the attention of conservationists is farmers’ protecting their

crops by killing popular vertebrates; for example, shooting kingfishers and herons

264 Part III Maintaining Biodiversity

at a fish farm. Sometimes, this pits farmers against species that are in jeopardy globally

but common enough locally to be considered pests by the farmers who have to live

with them. Think about the dilemma of an African farmer who lives near a herd of elephants,

each one of which eats about 150 kg of vegetation per day (Chiyo et al. 2005).

Even relatively subtle changes in farming practices such as timing can affect wild

life; here are two examples from the British Isles and Germany. When British farmers

shifted from spring-sown varieties of grain to autumn-sown varieties this reduced

the populations of lapwings, song thrushes, and rooks because these species were

dependent on the seeds and soil invertebrates brought to the surface by spring tilling

(O’Connor and Shrubb 1986). In Germany, a model of white storks’ foraging behavior

indicated that there would be much higher breeding success if nests were surrounded

by fields that were mowed asynchronously, thus creating a steady supply of newly

mown sites, their optimal foraging habitat (Johst et al. 2001). A comprehensive

review of farming practices and their potential effects on wild life is beyond our scope

here. The basic point is that these practices need to be evaluated and perhaps changed

if cultivated ecosystems are to host a wide range of species.

Biological diversity also includes domestic species in all the myriad of forms developed

by plant and animal breeders. We will cover their conservation in Chapter 14, “Zoos

and Gardens,” but they raise an interesting issue relevant here: should conservationists

be concerned with maintaining cultivated ecosystems as important elements of biodiversity

in their own right, irrespective of their role as habitat for species? The answer for

many Europeans is “yes,” because they view the countryside as an ecological, cultural,

and aesthetic amenity. Indeed, the European Union has shifted its subsidies to farmers

away from support for commodity production toward encouraging them to provide

broad environmental benefits (Kleijn and Sutherland 2003; Firbank 2005).

Minimizing the Negative Effects of Cultivated Ecosystems

Many cultivated ecosystems share a landscape with sizable tracts of natural and

seminatural ecosystems, and therefore it is important to minimize the extent to which

cultivated ecosystems impinge on ecosystems that are more critical for biodiversity.

Fortunately, in this regard good farming is good for biodiversity in some important

ways. For example, responsible farmers are vigilant against soil erosion, and this will

minimize problems with sediment pollution. Similarly, conservative, careful use of

fertilizers and pesticides will save farmers money and ameliorate problems with

eutrophication and pesticide contamination (Matson et al. 1997; Stoate et al. 2001).

Minimizing the use of pesticides can also have a direct positive return for agriculture

because all farmers are dependent on healthy soils (with their myriad of organisms)

and many need the assistance of beneficial insects (notably, pollinators and natural

enemies of pest species) (Collins and Qualset 1999). Integrated pest management (often

abbreviated IPM) is a good example of this, for it uses natural enemies of pests, specific

cultivation practices (e.g. mixing crops), and conservative use of pesticides to

achieve pest control (Koul et al. 2004). One of the primary goals of sustainable

agriculture is to maintain profits for farmers by minimizing costs, and this means

limiting soil loss and the expensive use of pesticides and fertilizers.

Ironically, one undesirable “export” from cultivated lands can be wild life. Many species

are quite successful at living along the interface between cultivated and natural or

Managing Ecosystems 265

seminatural ecosystems, such as various members of the deer, crow, and

kangaroo families and quite a number of small mammalian carnivores

such as red foxes and raccoons. Farmers have long been familiar with the

losses sometimes inflicted by these species, but their depredations on

other native wild life can be critical too (Cote et al. 2004).

Some of the negative effects of cultivated ecosystems can be ameliorated

by limiting their extent through increases in their productivity. The

more commodities we obtain per unit area, the more room there is for

natural ecosystems (Box 12.1) (Hunter and Calhoun 1995; Sedjo and

Botkin 1997). Of course, there are some important pitfalls hidden here.

In particular, the emphasis must be on achieving sustainable, long-term

increases in production without excessive exports of pesticides, fertilizers,

and soil. Furthermore, one way to increase productivity is through the

use of genetically engineered or genetically modified organisms (GEO or

GMO), but most conservationists are too concerned about the risks

involved to endorse their use, at least until much more research is undertaken

(Snow et al. 2005). With such reservations clearly in view, we still

have ample opportunity to increase the productivity of many cultivated

lands through intelligence, innovation, and diligence, and for many

species this may have a greater net benefit than trying to increase the

quality of their habitat on cultivated lands (see Green et al. 2005b for an

analysis of this issue).

We also need to consider the juxtaposition of natural, seminatural,

cultivated, and built ecosystems on the landscape to minimize the

effects of cultivated ecosystems. As discussed earlier, from a biodiversity

perspective buffering reserves from cultivated and built ecosystems

is desirable, sometimes essential. On the other hand, farmers can often

benefit by proximity to natural or seminatural ecosystems: for example,

by increasing visitation by pollinators and pest-consuming animals

(Fig. 12.6; Kremen et al. 2002). Having seminatural ecosystems as

transition zones between natural and cultivated ecosystems will often

balance various needs.

Some Economic Perspectives

If society expects farmers, ranchers, fishers, and loggers to adopt practices

that are amenable to maintaining biodiversity, what should we

offer in return? Our respect? Some money? We will cover many aspects

of these issues in Chapters 15 and 16 (“Social Factors” and

“Economics”), but a quick description of two compensation mechanisms

is in order here. Many governments offer various financial subsidies

to farmers and fishers, and these have often encouraged

environmental destruction that did not even make sense financially.

These subsidies can be reoriented toward practices that are deemed

environmentally acceptable, as is happening in Europe currently

(Kleijn and Sutherland 2003; Firbank 2005). Such annual payments to “do the right

thing” go by many names and can be offered to anyone who owns or uses the lands

and waters, not just farmers (Main et al. 1999). Conservation easements are a

266 Part III Maintaining Biodiversity

Figure 12.6 Farmers who maintain

natural vegetation may benefit

from increased rates of

pollination. A study of California

watermelon farms compared

organic (O) and conventional

(C) farms that were near (N)

natural vegetation (over 30% of

the landscape within a 1 km

radius) or far (F) (less than 1%

native vegetation). (a) Total estimated

pollen deposition by native

bees (±SE) on organic near,

organic far, and conventional far

farms. (There were no conventional

farms near natural vegetation.)

The horizontal line indicates

the level of pollen deposition

required for production of marketable

fruit. (b) Native bee diversity

(circles) and abundance

(triangles) (±SE). During a twoyear

study, all CF, one OF, and no

ON farms brought managed honeybee

colonies to the fields to

achieve adequate pollination.

(From Kremen et al. 2002,

© National Academy of Sciences,

USA.)

one-time agreement to purchase certain property rights from landowners; typically,

the landowners can continue their traditional use of the land, but cannot convert it to

a more intensive use, especially development as housing, factories, mines, etc.

Easements and subsidies are widely accepted in conservation circles, in part because

modified and cultivated ecosystems are judged to be far preferable to the alternative of

having them developed into built ecosystems (Knight et al. 1995).

Built Ecosystems

The final group of ecosystems to consider are easily detected, especially at night.

These are the places where people live in great density and where, after dark, our

enormous use of energy is manifested by lights readily detected from airplanes and

Managing Ecosystems 267

BOX 12.1

A triad approach to land-use allocation1

From the perspective of producing commodities such as food, fiber, and fuel, it is possible to conceptualize a “triad” of

three types of land use: (1) cultivated ecosystems where high levels of commodity

production are achieved; (2) protected ecosystems with virtually no commodity

production; and (3) modified ecosystems in which modest resource use occurs,

while ecological values are carefully protected. Many environmentalists are reluctant

to be advocates of cultivated ecosystems because so much biodiversity has

been lost from the conversion of natural ecosystems to cultivated ecosystems.

However, in some circumstances it might make sense to switch commodity production

from extensive extraction in modified ecosystems to intensive production

in cultivated ecosystems so that more land can be set aside in reserves.

The forests of Maine provide a good example: fewer than 3% have been set

aside as reserves, roughly 6% are used for intensive forest management (e.g.,

tree plantations), and over 90% are used for extensive forestry. Intensive forest

management in Maine produces roughly four times as much wood as extensive

management, and thus for every hectare of forest switched from extensive

management to intensive management 4 ha could be put in reserves with no

net loss in commodity production. In other words, it would be possible to

increase Maine’s forest reserves from 3% to 10% and to compensate for all of

the lost production with a modest increase in the area of intensive production,

from about 6% to 8% in round numbers (Fig. 12.7). In aquatic ecosystems the

tradeoffs could be even more dramatic because aquaculture can easily produce

ten times as much fish, often much more, compared with catching fish in seminatural

ecosystems. This tradeoff would be particularly attractive because the

world’s aquatic ecosystems are overwhelmingly skewed toward extensive management,

with very little area allocated to aquaculture or aquatic reserves.

Some conservationists think trades like these make sense. Others believe

that we should set aside the reserves anyway and make up for the loss of production

by reducing human populations and consumption. No doubt the latter

approach would solve the problem, but which approach is more feasible?

1 Based on Seymour and Hunter (1992) and Hunter and Calhoun (1995).

Figure 12.7 The current allocation

of Maine’s forests from a triad perspective

and what the allocation

could be if some trade-offs

between cultivated ecosystems and

reserves were made.

spaceships. In these ecosystems – cities, factories, mines, highways, and the like –

human-made structures are dominant, and the hand of nature can be difficult to discern.

However, nature is still there, even if it has been reduced to rats and cockroaches

hiding in the recesses of a building, a crust of lichens and lichen-inhabiting

invertebrates on a bridge abutment, or a line of weeds growing through the cracks in

an abandoned parking lot. Some people are reluctant to think of cities as ecosystems,

but they do meet our definition: they constitute a physical environment plus interacting

populations (Chapter 4). A child feeding pigeons on a city street is participating in

an ecological interaction, even though the solar energy in the bread crumbs was

fixed by a wheat plant far away (Gilbert 1989; Pickett et al. 2001; Faeth et al.

2005).

Built ecosystems are not a major focal point for conservation biologists because

they are primarily habitat for very adaptable species that are in no danger of

extinction. You might guess from their names alone that house finches, house

mice, house sparrows, house geckos, and bedbugs are able to survive in close proximity

to people. Nevertheless, it would be a mistake to ignore these places completely

for at least three reasons that we will consider here.

Habitat for People

In most industrialized countries the vast bulk of people already live in urban and

suburban environments and across the globe human populations are shifting

toward urban areas (Palmer et al. 2004). This pattern is generally conducive to

maintaining biodiversity because, if all of these people were scattered across the

countryside, far less land would remain in natural and seminatural ecosystems.

Consequently, conservationists have an interest in built ecosystems being pleasant,

healthy places so that people will live there. This rationale applies also to recreation.

Wild life will fare better if people spend an afternoon at the city park or in their

backyard rather than drive to a beach where endangered piping plovers are trying

to nest, or worse yet, build a vacation home on the dunes. One way to make urban

and suburban life more pleasant is to facilitate positive interactions with wild life:

encounters with robins, daisies, and dragonflies rather than rats and ragweed. Such

contact may also encourage people to support conservation with their votes and

their money and may provide nutriment and inspiration for young conservation

biologists (McKinney 2002; Louv 2005; Miller 2005).

Biodiversity in Built Ecosystems

Many built ecosystems harbor a surprising variety of wild life, species that cling to

any oasis of green in a concrete desert (McKinney 2002; DeStefano and DeGraaf

2003) (Fig. 12.8). Fruit bats roost in a tree that overhangs one of the main streets of

Kathmandu. Peregrines wing through the canyonlands of several North American

cities searching for pigeons. In the southwestern United States many seminatural

ecosystems are dotted with abandoned mine shafts, which represent small, humanbuilt

habitats for rare bats and many other species. One analysis of urban landscapes

in Germany found relatively high species richness of native plants, which the authors

attributed to cities being situated in places with heterogeneous physical environments

268 Part III Maintaining Biodiversity

(Kuhn et al. 2004). The fact that cities tend to be located in places with fertile soils

and benign climates may also play a role (Schwartz et al. 2002; Gaston 2005). Of

course, most urban species are quite common, and peregrines and eastern barred

bandicoots are unusual exceptions to this pattern. Nevertheless, it is important to

remember that there are more urban species that merit our esteem than our disdain,

more native butterflies than exotic cockroaches.

It is interesting to speculate that urban populations of some species may be genetically

different from their conspecifics living elsewhere. Perhaps, for example, some

urban plant populations are more tolerant of ozone than rural populations of the

same species. The famous story of industrial melanism in moths (Chapter 5) suggests

that this is not a farfetched idea and that it may be of practical importance. Any allele

that increases the fitness of individuals in human-altered environments has a fair

chance of spreading, and it might allow an entire species to persist in our changing

world. The possibility of genetic adaptations to urban settings is another argument for

maintaining viable populations of species across their entire geographic range,

including built ecosystems.

Imports and Exports

Built ecosystems interact with other ecosystems in a far-reaching network.

Tremendous quantities of energy and matter are imported – notably fossil fuel,

electricity, food, and building materials – often coming from thousands of kilometers

away. Tremendous quantities of wastes are exported. Air pollutants travel

downwind. Solid wastes travel to open spaces, often nearby or sometimes far away.

Managing Ecosystems 269

Figure 12.8 In

urban landscapes

oases for quite a

few species of wild

life can be found in

parks, backyards,

cemeteries, etc.

Canberra, the capital

of Australia, is

home for over

300,000 people

and a remarkable

diversity of wild

species because of

city planning that

maintained large

areas of open

space. (Photo from

M. Hunter.)

Most major urban areas are on the shores of rivers or the ocean, where currents

can carry water pollutants away. Clearly, these imports and exports are of direct

concern to natural resource managers trying to maintain biodiversity in the

ecosystems where the energy and matter are acquired or where the wastes are

disposed.

How to Do It

These three issues can be crystallized into a single goal: making built ecosystems

inhabitable for both people and other life forms. Pursuing this goal involves activities

that are the cornerstones of environmentalism (pollution abatement, curbing

resource use, recycling, etc.) and that need no elaboration here. (Although it is worth

pointing out that college campuses are ripe for local action [Barlett and Chase 2004].)

It also requires activities that are a bit closer to mainstream conservation biology –

notably, managing the patches of green that dot the urban and suburban landscape

(Gilbert 1989; McKinney 2002). These city parks, backyard gardens, cemeteries, golf

courses, and the like conform to our definition of cultivated ecosystems, but they fit

here better than in our preceding discussion of farms, because they are so closely

linked to built ecosystems. They differ from rural cultivated ecosystems quite significantly

because they are managed primarily for their aesthetic qualities rather than

commodity production. Sometimes, this means monocultures of exotic species; witness

the expanse of lawns that we maintain with liberal inputs of pesticides, fertilizers,

and fossil fuels (Bormann et al. 2001). Yet aesthetic considerations also foster

diversity. They encourage people to grow a variety of flowers, shrubs, and trees, and,

whether intended or not, a variety of associated animals. Indeed, more and more people

are thinking of gardens and city parks as habitat for wild life, not just a pretty

place to play croquet. People are replacing lawns with patches of native plants and

focusing on plant species that will provide food for birds and butterflies (Johnson et al.

2004; Mizejewski 2004). We do not have space to describe all the techniques for wild

life gardening, but there is abundant literature on the subject. Wild life gardening

gives everyone an opportunity for hands-on action, even if it is only maintaining a

window box. Much of the work outlined here may be in the realms of urban planners

and horticulturalists, but conservation biologists have a role too, for example, in

pointing out the importance of ecological connectivity to sensitive species (Rubbo and

Kiesecker 2005).

Restoring Ecosystems

Scan the landscape from any vantage point near the Mediterranean – the Acropolis,

Mount Sinai, the seven hills of Rome – and you will witness what thousands of years

of human occupation have done.

270 Part III Maintaining Biodiversity

in those days the country ... yielded far more abundant produce ... in comparison of what then was, there are

remaining only the bones of the wasted body as they may be called ... all the richer and softer parts of the soil having

fallen away and the mere skeleton of the land being left. But in the primitive state of the country its mountains

These are not the words of a twentieth-century naturalist; they were written by

Plato over 2000 years ago (quoted from Forman and Godron 1986). Plato understood

what was being lost with a clarity that would be uncommon among most current

inhabitants of the Mediterranean basin. It is hard to fully appreciate ecosystem degradation

unless you have seen it happening within your lifetime, and much of the

Mediterranean Basin suffered its most profound losses long ago. In many other parts

of the world, natural ecosystems are being degraded today at a pace so fast that even

young conservationists will have some personal experience with these changes.

What can be done about all these degraded ecosystems – the woodlands of the

Mediterranean Basin, the deforested lands of Amazonia, the polluted rivers of

Europe? Recall our discussion on global change (Chapter 6), and you will realize that

degraded ecosystems will eventually recover. Someday, after the era of Homo sapiens

has passed, even the hills of the Mediterranean will probably have a flora and fauna

as rich as it ever was. Unfortunately, natural recovery processes are likely to be very

slow; Fig. 6.1 suggests that in the worst cases several million years of evolution might

be required. However, we do not have to wait. We can accelerate the recovery process

if we wish.

There are many good reasons to restore ecosystems, but biodiversity advocates support

restoring degraded ecosystems for one overarching reason (Dobson et al. 1997).

At best, protecting natural ecosystems can only retain what we have, and wisely managing

seminatural, cultivated, and built ecosystems can only avoid future degradation.

If we want to reverse past degradation, we must think in terms of improving

damaged ecosystems. Improvement can mean many different things. For a cultivated

ecosystem degraded by erosion it might mean an increase in productivity. For a

seminatural forest degraded by excessive logging it might mean restoring its ability to

provide habitat for an endangered species. For a protected ecosystem it might mean

removing an exotic species so that the ecosystem is closer to its original state. To clarify

what improvement means we need to explore the concept further and, in the

process, define some terminology.

Some Terminology for Improving Degraded Ecosystems

It is easy to understand ecosystem degradation and improvement if we think in

terms of an ecosystem moving through a conceptual space defined by ecosystem

Managing Ecosystems 271

were high hills covered with soil, and the plains ... of Phellus were full of rich earth, and there was abundance of

wood in the mountains ... not so very long ago there were still to be seen roofs of timber cut from trees growing

there, which were of a size sufficient to cover the largest houses; and there were many other high trees, cultivated

by man and bearing abundance of food for cattle. Moreover, the land reaped the benefit of the annual rainfall, not

as now losing the water which flows off the bare earth into the sea, but, having an abundant supply in all places,

and receiving it into herself and treasuring it up in the close clay soil, it let off into the hollows the streams which it

absorbed from the heights, providing everywhere abundant fountains and rivers, of which there may still be

observed sacred memorials in places where fountains once existed. Such was the natural state of the country which

was cultivated. (Critias, 111.b,c,d)

structure and function. In Fig. 12.9 the filled circle represents a healthy structure

(e.g. high diversity) and function (e.g. high productivity), while the empty circle

represents the same ecosystem with a structure and function that have been

degraded by some human activity. If the degradation process is stopped, the

ecosystem will recover over time. Initially, the ecosystem may continue to degrade

for a while, especially if severe soil erosion occurs, but, eventually, it will probably

move toward its original state because of ecological succession. If the scope of

degradation is great, then the recovery may take a long time (centuries or

longer) and may only be approximate. Restoration ecologists often describe the

“let-nature-take-its-own-course” option as neglect, a word that clearly shows their

preference for active management and improvement. “Recovery” would be a more

neutral term.

The type of improvement most in concert with the goals of conservation biology is

restoration, which means actively trying to return the ecosystem to its original state.

Many ecosystem ecologists tend to emphasize function over structure, and thus they

would concentrate on restoring an

ecosystem’s productivity and nutrient

cycling. Conservation biologists

usually would not be satisfied with

this; they would also attempt to

restore an approximate replica of

the original biota.

Restoration ecology as we have

just defined it narrowly is distinct

from some closely related activities

because ecosystem managers

sometimes try to improve an

ecosystem without returning it to

an approximation of its original

state. Rehabilitation of a degraded

ecosystem means shifting it back

toward a greater value or higher

use than it is serving currently, not

necessarily all the way to its original

state. “Greater value” and

“higher use” can be broadly

defined, but usually reflect human

instrumental values. Reclaiming a

mine site as pasture for livestock

rather than restoring it to its former

state as a natural grassland

would be an example of rehabilitation.

(“Reclamation” is another

common synonym for rehabilitation.)

Sometimes, the goal is

replacement of a degraded ecosystem

by creating a completely new

272 Part III Maintaining Biodiversity

Figure 12.9 A conceptual representation of ecosystem degradation,

restoration, and related processes. See the text for an explanation; for

each line on this graph there is an italicized term in the text. (Redrawn

by permission from Bradshaw 1984.)

one. Creating a marsh in a mine pit that was formerly a forest would constitute

replacement. Replacing terrestrial ecosystems with wetlands is quite common in the

United States because laws often compel people who destroy one wetland, to build a

road, for example, to create a new wetland somewhere else.

Finally, enhancement is used for any activity that improves the value of an ecosystem,

even if the change is rather limited. This term can even include activities that,

depending on how you measure value, improve an ecosystem that has not been

degraded, as shown in Fig. 12.9. We have already discussed one example, installing

water holes in desert reserves. Similarly, waterfowl managers often enhance wetlands

by putting in water control structures that allow them to maintain the type of vegetation

favored by ducks. Conservation biologists will usually be skeptical of enhancing

undegraded natural ecosystems because they will wonder what species may be

harmed by the manipulation.

The issue of ecosystem restoration, reclamation, and so on often arises when discussing

mitigation of the impact of a proposed development, especially roads, airports,

shopping malls, etc., that will profoundly degrade a site. There are four major forms of

mitigation. First and most ideally, the impact should be avoided altogether; for example,

by relocating the development to a site that has already been severely degraded.

Second, if the impact cannot be avoided, the site should be restored, or at least rehabilitated,

after the impact is over; for example, after a mine is exhausted. Third, if the

impacts are relatively permanent, another nearby degraded site should be restored to

replace the one lost. Fourth, the developer can be required to purchase and permanently

protect natural ecosystems, preferably at a ratio of several hectares protected

for every one lost.

Six Basic Steps for Restoring an Ecosystem

1 Set a goal. Do we wish to restore the preexisting ecosystem, or is it only feasible

to rehabilitate the degraded ecosystem? It is important to be realistic, especially

because ecosystem restoration can be quite expensive. The total bill for restoring

the Everglades will be tens of billions of dollars (Holl and Howarth 2000). Given

the dynamic nature of ecosystems (recall Fig. 6.5) and the long history of degradation,

we will also need to decide which preexisting ecosystem to restore, the one

that was present ten years ago, or that present 300 years ago. Conservationists

often desire to restore ecosystems to a state that existed before the colonization of

people, at least technologically advanced people (Angermeier 2000; MacDougall

et al. 2004). However, if we choose to restore an ecosystem to an ancient state,

we need to recognize that the ecosystem we hope to restore would have changed

even in the absence of people. To put it another way, the natural (undegraded by

human activities) state of an ecosystem is a moving target because of long-term

climate change, species range shifts, and other factors. Finally, once a general

goal has been set, it can be translated into a specific set of objectives, usually by

comparison with a benchmark ecosystem that exhibits the desired state, or reference

conditions (Kuuluvainen 2002). In sum, setting a goal requires answering

both ethical (what do we want?) and technical (exactly what does that look like?)

questions.

Managing Ecosystems 273

2 Determine a strategy and methods. Ecosystem restoration is not easy because,

to paraphrase Frank Egler (1977), not only are ecosystems more complex than we

think they are, they are more complex than we can think. This complexity is daunting,

but it must not be an excuse for inaction. It does mean that ecosystem restorationists

need to do their homework; to understand the ecosystem in question as

thoroughly as possible; and to work out a plan of attack with other experts such as

civil engineers, landscape architects, horticulturalists, and other specialists, including

social scientists who can help ensure community support (Gobster and Hull

2000). Restoration projects often offer unique opportunities for public education

and involvement.

Interestingly, ecosystem restoration can give to the science of ecology as well as

take from it because it represents an experimental application of our knowledge of

ecosystem function and structure. As Bradshaw (1987) put it, “Ecologists working

in the field of ecosystem restoration are in the construction business and, like their

engineering colleagues, can soon discover if their theory is correct by whether the

airplane falls out of the sky, the bridge collapses, or the ecosystem fails to flourish.”

It is wise to learn from the mistakes of others, and, fortunately, ecosystem restoration

has been the subject of many books (e.g. Bradshaw and Chadwick 1980;

Sauer 1998; Perrow and Davy 2002) and is covered in two journals: Ecological

Restoration and Restoration Ecology. Note that successful restoration ecology projects

also incorporate the social sciences.

Every restoration project is unique. Even steps as fundamental as 3, 4, and 5 are not

required in every project, and the specific execution of these steps will always vary.

3 Remove the source of degradation. This step is obvious and critical: you cannot

recover from a knife wound until you have removed the knife. We cannot restore a

eutrophic lake until we remove the source of excess nutrients. We cannot restore

an overgrazed grassland until we have removed much, if not all, of the livestock.

In some cases, especially on islands, exotic species are the primary source of degradation

and must be removed to initiate restoration (Campbell and Donlan 2005;

Cruz et al. 2005). In other cases, exotic species can be removed later while fine-tuning

the ecosystem restoration process, and may even have a role in furthering the

restoration process; for example, by stabilizing soils (Ewel and Putz 2004).

Sometimes, the source of degradation will have disappeared before the restorationist

arrives on the scene (e.g. the bulldozers will be gone), but if not this is the

first “hands-on” task.

4 Restore the physical environment. In some cases restoring physical structure is

sufficient; for example, coral reef restoration sometimes begins with providing suitable

substrates for coral colonization (Fox et al. 2005). Often restoring the physical

environment is far more complex. In most terrestrial and wetland ecosystems soil is

a critical issue. If it is eroding, it must be stabilized; if it has already eroded away or

is contaminated it must be replaced. Unfortunately, replacing soil by importation is

expensive and depletes the supply of soil at the other site, while rebuilding the soil

on site is a long process.

Restoration of an ecosystem’s hydrologic regime is often essential, especially in

aquatic and wetland ecosystems (Poff et al. 1997). Sometimes much can be

accomplished through changing the management of water control structures, but

274 Part III Maintaining Biodiversity

in many cases the enormous network of dams, dikes, canals, and so on will need to

be redesigned or even removed (Hart et al. 2002). Similarly, restoration of a disturbance

regime is often critical; in particular, returning fire or grazing to grasslands

and woodlands is often an issue, as we discussed earlier (Poyry et al. 2004; Van Lear

et al. 2005).

5 Restore the biota. Given time many species would recolonize a suitably restored

environment, but this process can be accelerated significantly by translocating populations

– collecting appropriate plants and animals and moving them. (The next

chapter will cover translocations in more detail.) Plants are usually the priority for

restoration projects because they provide habitat for the animals, and many animals

are mobile enough to colonize on their own after suitable vegetation is growing

(Bradshaw 1983). Simply finding enough suitable specimens for importation

can be difficult, especially because we do not want to overexploit the ecosystem

where we obtain the colonists. Whenever possible, it is best to work with any

organisms that survive on the site rather than undertake the expense and risk

of importing new ones. For example, restoring a degraded forest may involve

manipulating the age-structure of the current population by thinning, a much

easier proposition than planting new trees (Frelich and Puettmann 1999;

Allen et al. 2002).

Conservation biologists are particularly interested in restoring rare species, but

often these will be the most difficult to obtain and establish (Maina and Howe

2000). In the worst cases, some of the ecosystem’s original inhabitants will have

become extinct. If substitutes of a different subspecies are available, these are generally

deemed appropriate for reintroduction as long as they are likely to be

adapted to site conditions (Seddon and Soorae 1999; McKay et al. 2005), but the

issue is more difficult when an entire species is globally extinct. Consider the

dilemma of European conservationists who would like to restore a forest complete

with a population of aurochs, or a North American longing for a grassland

ecosystem with a mammal fauna as rich as that before the Pleistocene extinctions.

Most conservationists would argue that we should do the best we can with extant,

native species, but some people have argued that we should introduce ecological

equivalents of extinct species: for example, moving African elephants and cheetahs

to North America to replace those lost during the Pleistocene extinctions

(Donlan et al. 2005).

6 Be patient. It can take many years for reintroduced individuals to grow, populations

to increase, other species to colonize, and so on. In the meantime the site

should be carefully monitored so that the next restoration project will be based on a

larger foundation of knowledge.

A Cautionary Note

Sometimes, promoting ecosystem restoration can have an unintended side effect.

The real or perceived opportunity for restoration can make it easier to justify additional

ecosystem degradation. If miners promise to replace an abandoned field with a

beautiful lake surrounded by a lush forest, they will find it easier to win approval of

their proposal. Conservationists need to be conservative on this point because

Managing Ecosystems 275

ecosystem restoration has a significant risk of failure even when undertaken with

great care and diligence (Ruiz-Jaen and Aide 2005). In short, the promised lake

ecosystem may turn out to be just a barren body of water. At best, it is not likely to be

a perfect replica of a natural lake ecosystem.

276 Part III Maintaining Biodiversity

CASE STUDY

Forests of the Pacific Northwest1

Some of the world’s most spectacular forests lie in a broad band paralleling the Pacific coast from northern

California to southeastern Alaska. Ample rainfall, mild winters, and fertile soils allow trees to grow to prodigious

size (Fig. 12.10). These same conditions, plus the wide range of microhabitats created by having exceptionally tall

trees and exceptionally large reservoirs of dead wood, support a diverse flora and fauna. From a human perspective,

all of this represents a rich lode of natural resources, notably, timber, salmon, and opportunities for outdoor recreation.

Unfortunately, it also creates an arena for managing ecosystems in which the stakes are high and the potential

for conflicts is great.

Humans arrived in this region relatively recently: several thousand years ago in the case of people immigrating

from Asia across the Bering land bridge; in the nineteenth century in the case of settlers from the east coast of

Figure 12.10 The forests of the Pacific Northwest are some of the richest temperate forests on the planet in

terms of both their biological wealth and their value for timber. (Photo by Marc Adamus.)

Managing Ecosystems 277

North America. This relatively short tenure and the overall abundance of natural resources may explain why loggers

have not entered a fairly high percentage of the region’s forests, relative to other temperate forests in the world.

Estimates of this percentage will vary, particularly depending on how we define the region’s northern boundary, but

may be roughly 15–25%. To someone concerned with maintaining biodiversity, these remaining virgin forests are a

small legacy that must be carefully protected in reserves. To someone concerned with maintaining the health of the

timber industry, these remaining forests represent billions of dollars worth of standing timber, as well as land that

can be allocated to growing more timber in the future. There are other perspectives as well – for example, those of

people who treasure the region’s wild places as a setting for outdoor recreation and those of people who value

salmon as a commercial and recreational resource and who recognize the link between healthy forest ecosystems

and healthy salmon populations. However, we will focus on the issue of biodiversity versus timber, particularly as it

is being addressed in the United States.

Initially the issue was seen as spotted owls versus timber, at least in the southern end of the region. In reality

the spotted owl was essentially a flagship species for environmentalists to rally public attention and a scapegoat for

the timber industry to pit against the welfare of people. Legally speaking, the spotted owl was a vehicle for addressing

the larger issue of maintaining old forest ecosystems because it is protected under the US Endangered Species

Act. This means that its habitat must be protected, and its habitat consists largely of these old remnant forests, often

several hundred hectares per pair.

The first response to protecting spotted owl habitat was establishing small reserves (Spotted Owl Habitat Areas,

SOHA) around many of the known sites occupied by owls. Soon the inadequacies of this approach became apparent,

and the focus switched to identifying areas of many thousands of hectares that would hold 20 or more owl territories

(Habitat Conservation Areas, HCA) and to maintaining significant forest cover (>40% canopy closure on

half the area) between the HCAs to facilitate owl dispersal. Neither of these approaches specifically considered the

needs of species other than spotted owls.

The third approach, devised by a Forest Ecosystem Management Assessment Team and widely known as FEMAT,

involved identifying a large set of Late-Successional Reserves and Riparian Reserves designed to protect virtually the

entire suite of species associated with old forests, including salmon and other species associated with forest streams.

Ostensibly, this was an improvement, but environmentalists were disappointed with the specific plan because it still

opened some areas of old-growth forests to commercial logging. Furthermore, it allowed some thinning of stands

and salvaging of dead timber in Late-Successional Reserves that would presumably require road access. The FEMAT

approach also attempts to improve management of federally owned forests outside of the reserves so that they will

provide some habitat for a greater array of species. Specifically, it requires retaining some trees after clearcutting to

accelerate the development of vertical structure in logged stands.

The picture painted here applies only to the roughly 50% of forest lands that are publicly owned. The other half

of the forest is primarily owned by large timber corporations, and their management is quite different. Virtually

all of the old-growth forests have been cut, and the major emphasis is on growing a single species, Douglas fir, on a

40- to 80-year cutting cycle. This usually involves clear-cutting a site, planting seedlings, and using various silvicultural

techniques to accelerate growth. Management is usually intense enough to consider these forests to be cultivated

ecosystems.

It remains to be seen how well the biota of this region will be served by this mixture of natural, modified, and

cultivated forests. Certainly, it will fare better than the wild life of places like Europe that have a long history of

intensive land use, but it will be compromised to some degree.

1 This account is distilled from Harris (1984), Hunter (1990), Forest Ecosystem Management Assessment

Team (1993), Franklin et al. (1997), Spies and Turner (1999) and personal communication with

Jerry Franklin.

278 Part III Maintaining Biodiversity

CASE STUDY

Restoration of the Iraq Marshes1

Images of Iraq in contemporary media are of a hot, dusty land, but 5000-year-old clay tablets residing in museums

depict enormous expanses of lush marshlands. Indeed through the 1980s wetlands in southern Iraq spanned an

area twice the size of the Florida Everglades (Fig. 12.11). The marshes are internationally significant for their birdlife

and support many unusual and rare species. These include two endemic breeding birds: the Iraq babbler and the

Basra reed warbler. Many endangered species also winter in the area: Dalmatian pelican, pygmy cormorant, marbled

teal, white-tailed eagle, and slender-billed curlew. It has also been a vital overwintering area for several million

migratory waterfowl. Moreover, several hundred thousand people known as “marsh Arabs” thrived in the marshes,

living by fishing, hunting birds, and grazing their water buffalo. Many biblical scholars regard the marshes as the

site of the legendary “Garden of Eden.” In modern times, this wetland complex was a massive water-treatment system

that released clean water to the Persian Gulf and provided vital nutrients and spawning areas that sustained

fisheries both in the marshes and in the Persian Gulf.

Widespread destruction of the southern marshes began in 1991 right after the first Persian Gulf War. An uprising

of Shi’ite rebels against the regime of Saddam Hussein failed and many rebels fled to the marshes. To destroy

their refuge Saddam Hussein ordered the construction of two canals and several dams to divert river flows away

from the marshlands and into the desert, and also large-scale burning of the marshland vegetation. The projects

had enormous and immediate destructive effects. In 2000, a report by the United Nations Environment Program’s

Division of Early Warning and Assessment suggested that 90% of the marshes had disappeared. By 2003, experts

feared that the entire wetland along with its biota would disappear entirely unless urgent action was taken. What

was once a vast, interconnected mosaic of densely vegetated marshlands and lakes teeming with life had become a

mostly lifeless desert of salt-encrusted lakebeds and riverbeds.

Figure 12.11 A

vast wetland complex

in southern

Iraq, home to

the Marsh Arabs

and abundant wild

life, has been

devastated by

conflicts but is now

being restored.

(Photo from Jassim

Al-Asadi, Center

for the Restoration

of Iraqi Marshlands,

Iraq Ministry of

Water Resources.)

Managing Ecosystems 279

After the 2003 allied occupation of Iraq, the United States government funded a plan called “Eden Again” to

recover the marshlands, and the government of Japan funded implementation of the plan. Dikes that held water

back from the marshes were breached and uncontrolled releases of Tigris and Euphrates River waters were made.

By March 2004 nearly 20% of the original 15,000 km2 marsh area was reflooded. As of 2005 as much as 50% of

the marshes had been reflooded. Restoration is failing in some areas because of high soil and water salinities, but

elsewhere rapid reestablishment, high productivity, and reproduction of native flora and fauna in reflooded areas

suggest that the marsh restoration will be successful. The key will be ensuring sufficient flow of noncontaminated

water and flushing of salts from the ecosystem. Moreover, the tenuous political situation in Iraq will determine

whether the restoration efforts will be sustained. With continued attention the legendary Garden of Eden and the

unique and abundant forms of life it supports will likely flourish again.

1 Key sources used were Munro and Touron (1997), Bonn (2005), and Richardson et al. (2005). Useful websites

are the United Nations Environment Programme’s Iraqi Marshlands Observation System (IMOS)

(http://imos.grid.unep.ch) and the “Eden Again” Project (www.edenagain.org).

Summary

Managing ecosystems to maintain biodiversity requires a diverse mixture of

approaches, including the following: protecting natural ecosystems in reserves; combining

biodiversity conservation and commodity production (e.g. forestry and fisheries)

in modified, seminatural ecosystems; managing cultivated and built ecosystems

to ensure that they efficiently provide for human well-being without having a negative

impact on other ecosystems; and restoring degraded ecosystems. Modified ecosystems

dominate the earth’s surface, and thus it is essential that they provide habitat for

most biota in addition to connectivity among reserves. This can be accomplished if

these ecosystems are managed in a way that is as consistent as possible with natural

processes, for example, managing livestock to imitate the role of native herbivores.

Cultivated and built ecosystems do provide habitat for some species, but they are generally

not species jeopardized with extinction. Conservationists need to ensure that

these ecosystems are safe, enjoyable places for people to live in and that they produce

most needed commodities so that the pressure on other ecosystems is minimized.

Finally, all of the activities described above can only maintain the status quo; if we

want to restore an ecosystem that has been degraded by human activities, we must

make a special effort.

FURTHER READING

For more information about managing particular types of ecosystems for biodiversity see Hunter (1990, 1999) and

Lindenmayer and Franklin (2002) on forests, Samson and Knopf (1996) on rangelands, Wilcove and Bean (1994)

and Boon et al. (2000) on aquatic ecosystems, O’Connor and Shrubb (1986) and Collins and Qualset (1999) on

farms, Gilbert (1989) on urban areas, and Perrow and Davy (2002) on restoration ecology. For some ideas about

what you can do on campus see Barlett and Chase (2004). See www.iucn.org/themes/cem/ for the website of the

IUCN Commission on Ecosystem Management. See Grumbine (1994), Callicott et al. (1999), and Dale et al. (2000)

for some conceptual treatments of ecosystem management.

TOPICS FOR DISCUSSION

1 Would you be willing to convert some portion of a 1 million hectare seminatural forest, currently modified by

regular logging, into a plantation if an equal portion of the forest were set aside as a reserve?

2 Comparing ecosystems modified by fisheries, forestry, or livestock grazing, which do you think pose the most

serious problems for conserving biodiversity? In which could the problems be solved most readily?

3 Should significant national funds be used for managing biodiversity in urban environments or should this be

solely the responsibility of local governments and thus paid for by local taxpayers?

4 Do you think that exotic species should ever be used in ecosystem restoration projects; for example, planting a

fast-growing exotic plant species to avoid soil erosion, then removing it later?

5 In your region which types of ecosystems have experienced the worst degradation and loss? What steps could be

taken to restore them?

280 Part III Maintaining Biodiversity