CONCEPTS ENERGY IN ECOSYSTEMS
Every individual needs a specific physical environment as the biotic community
must interact with the abiotic community. In the habitat, there are very complex and
very complicated interactions between components, between communities and habitats,
but the interaction continues to run normally so that between the biotic community and
the habitat forms an ecological system or called an ecosystem. A system is an interaction
that unites existing components into a single unit and makes a certain function.
From another point of view, a system is a group of components that are
interrelated, and influence each other so that they can form a whole unit. The condition
of a good system is that the interaction between components must be harmonious and
balanced, the balance in the ecosystem is called a dynamic balance (steady state), which
is a balance that can undergo changes at any time that will be followed by various
processes so that it will end up with a new balance.
Energy is the power used to carry out the main energy source activity: sunlight. The
sun is directly utilized by green plants in electromagnetic form for the photosynthesis
process. Energy that enters the ecosystem is in the form of solar radiation energy or
light energy, but not all of it can be utilized. The stored energy in the form of plant
matter can be channeled through the food chain and food webs from producers to
consumers to decomposers. If the material is not consumed, the energy will be stored
in the system and then passed on to the decomposer. Each level of traffic in the food
chain uses energy to live and some of it is released as heat. Possibility of energy
export/energy to other ecosystems in the form of organic matter
A. DEFINITION AND ENVIRONMENT OF ENERGY
Energy is everything that can do work (heat energy, potential energy, chemical
energy).
- Law of Thermodynamics I: energy cannot be created and eliminated but can
change shape.
- Law of Thermodynamics II: the entropy of a system always increases, or a
system always goes to the irregular unless energy is added (dead organisms
always decompose but living organisms do not, because of the addition of
energy
From this explanation, it can be understood that no process involving energy
transfer can occur spontaneously unless there is energy degradation (hot objects
always become cold and here there is energy degradation). The energy of light during
photosynthesis is converted into chemical energy, but here there is also the
decomposition of energy. All organisms get their energy from solar energy through the
food chain where with each step of energy transfer there is some energy lost
Ecosystems are fundamentally related to the transfer of energy from solar energy
through the food chain. Organisms on earth receive radiation from the environment,
namely from the sun and light reflections from the earth, but only a small part of the
light energy can be used in the photosynthesis process which results in an energy
source for the biological components of the ecosystem.
B. PRODUCTIVITY CONCEPT
What is meant by the primary productivity of an ecosystem/community is the
speed of energy storage in the carbohydrate synthesis process (photosynthesis) by
producers, especially green plants in the form of organic compounds that can be used
as food ingredients.
The four steps in the production process are:
1. Gross Primary Production (=PK)/Gross Primary Productivity is all
photosynthesis results (including those used for respiration)
2. Net Primary Productivity (= PPB)/Net Primary Prod. It is the net result of
photosynthesis which can be described by the rate of accumulation of organic
compounds in plants
3. Clean community productivityIt is the storage speed of organic matter that is
not exerted by heterotrophs in units of time
4. Secondary productivity is speed
It is the speed of energy storage at the consumer level. Since consumers only take food
that has been produced by producers (after respiration) and then convert it into tissues,
secondary productivity is not divided into gross and net
Biological productivity is generally not the same as the productivity of the
chemical industry because in the chemical industry production is the result of the final
reaction but in the biological process the process continues to run and must be listed
at some time.
Biological productivity is generally not the same as the productivity of the
chemical industry because in the chemical industry production is the result of the final
reaction but in the biological process the process continues to run and must be listed
at some time.
The relationship between gross and net production can be explained by the leaft
area index (LAI) chart model. The LAI depicted with the X-axis can be considered a
measure of biomass photosynthesis. Maximum productivity is obtained at LAI around
4 (i.e. the surface area of the leaf exposed to light 4X the area of the soil surface).
However, gross production (GPP) is achieved if the LAI is 8-10, namely in old forests.
Net production (NPP= Net primary productivity) decreased at a high level due to
loss due to respiration to produce extensive leaves and their supporting tissues. In
conclusion, it can be said that nature will maximize GPP while humans will maximize
NPP.
1. Use of Primary Production by Humans
In developing countries the GNP is more than $600/year and 30% of the
world's population is in this state. In developing countries, the rate of population
growth of the country is less than 1%/year.
In less developed countries the GNP is less than $300/year and 65% of
the world's population is in this state. The rate of population growth in
underdeveloped countries is 2%/year. In underdeveloped countries, the
population lacks protein and even carbohydrates. Due to the large increase in
population, the increase in agricultural production cannot catch up. This is due
to a small increase in agricultural production due to no increase in energy (either
in the form of fertilizer or good irrigation).
2. Primary Productivity Measurement
In reality, productivity measurement can be done by means of measurement
based on indirect quantities, including by measuring.
• Number of compounds produced
• Raw materials produced
• By-products produced
3. Multiple Productivity Measurement Methods
a. Harvesting Methods
Measure the production of clean communities. It is used if a steady state
is never achieved. Generally, this method is used in cultivated plants. The
method is carried out by weighing the yield. This method is less thorough if
part of the result is eaten by herbivore.
b. Oxygen Measurement
Oxygen production can be used as the basis for measuring productivity.
The production of aquatic ecosystems can be measured by the diurnal curve
method. This method measures the production of dirty primary because the
oxygen produced during the day plus the oxygen produced at night is the
oxygen produced by the entire community.
In the lake there is an upper layer that is permeable to light and hot
temperatures called the epilimnion layer, while the lower layer is called
hipolymnion.
A measurement method called the hyperpolyminetic method measures the
amount of oxygen that disappears from the ecosystem, which describes the
amount of oxygen used for decay. In other words, the greater the productivity
of epilimonions, the more organic compounds will descend to the
hypominion, so that it will increase the ocsign necessary for decay. So the
hypolymonion method will measure net productivity.
c. Carbon Dioxide Method
This method is practical for terrestrial plants/organisms. During the day,
photosynthesis and respiration occur, while at night there is only respiration.
d. PH Method
There are aquatic ecosystems, the PH of water is a function of dissolved
carbon dioxide levels. Productivity measurement using this method must
prepare the curve in advance
e. Methods of Measuring Productivity with the Disappearance of Raw
Materials
The reduced content of available raw materials illustrates the level of
productivity. It is good to do it in aquatic ecosystems. This method measures
the community's net production
f. Determination of Productivity with Radioactive Materials
This method measures net productivity. Radioactivity can be used to
measure net productivity.
g. Method Chlorophile
This method is based on the chlorophyll content per area in a community.
Plants that are in the shade have more chlorophyll than plants that grow in
bright spots. Because of this, plants in the shade can ensnare more light
power, so their efficiency is high. Meanwhile, plants in well-lit areas have
lower efficiency. This method measures gross productivity.
C. FOOD CHAIN, FOOD WEB AND TROPHIC LEVEL
The food chain is the transfer of food energy from plant resources through
a series of organisms or through the food-eating route (plant – herbivore –
carnivore).
At each stage of displacement 80 – 90 % of the potential energy is lost
due to heat, therefore the steps in the diet are limited to 4 – 5 steps. In other
words, it can be said that the shorter the food chain, the greater the energy
available
There are two basic types of food chains:
a. Grazing food chain
Plants — herbivores — carnivores
b. Detritus food chain
Dead material → microorganisms (detrivores = waste-eating organisms) →
predators
Food chains will be interconnected to form a food web. A simple food chain
occurs in the polar regions in winter. This is due to the fact that in winter there is
little light, so there are few producer plants, as a result of which there are also
few herbivores and carnivores.
Organisms whose food source is obtained from plants with the same number
of steps are said to have the same trophic level. Trophic level 1 is the producer,
level II is herbivores and trophic level III is carnivores (consumers II). The
classification of organisms based on trophic level (food level) is based on the
function of organisms in the food chain and not based on species. Therefore a
single species in a population can occupy more than one food tier.
Of the 100% of sunlight that can be used for photosynthesis only 1%, while
80-90% of the potential energy of food will be lost in the transfer of energy in
food. Therefore only a small human population can be supported by a society
(population) whose main diet is meat, because to produce meat requires a long
food chain
In insect extermination by spraying with DDT, it will be absorbed by detritus
→ microbes → invertebrates (worms, attackers) → fish, bird crabs →
In this case, there will be an accumulation of DDT residues in the last food
chain. This event is called food chain concentration or biological magnification
(biological magnifican). DDT or other compounds containing chlorine can affect
the formation of eggshells in considerable quantities and result in eggs breaking
easily before the chicks hatch and this can lead to the extinction of certain birds.
So concentrations of substances that are not good for individuals can be deadly
for the population. Therefore, pest eradication should be done by biological
means, namely with natural enemies.
1. Ecological Efficiency
Ecological efficiency is a comparison of energy flows at various points
along the food chain in percent. In calculating the dimensional efficiency
must be the same, meaning that the numerator and denominator are expressed
in the same unit, for example measuring the efficiency of chicken food, then
meat and food must be measured in a dry state (hours/Kg). It is best if the
measurement is in % calories.
For example, a chicken farmer said that the efficiency of changing
chicken eating to meat was 40% (Pt/It). In this case, please keep in mind that
the weight of meat in the wet state is equivalent to 2 Kcal/gram, while the
meal of chicken is weighed in a dry state and is equivalent to 4 Kcal/gram.
So the efficiency is actually less than 20%
In the energy transfer between trophic levels (food levels), PG/L = 1 – 5
% : PG/LA = 2 – 10 %, while the production efficiency between food levels
= 10 – 50 % or greater. If the organism is fed a good diet, which consists of
calories and proteins then the efficiency is close to 100% and part of the
energy is assimilated for growth.
Actually, it is not appropriate to compare the efficiency of a long-lived
ecosystem with a short-lived machine. This is because some of the ecosystem
energy is used for repair and growth in addition to being lost as heat while
machines cannot repair themselves. In addition, the rapid growth of the
ecosystem per unit time has a greater survival value compared to high
efficiency. In the use of analogous fuels, it is more important to achieve the
goal at high speed but less efficient than driving slowly and for a long time,
but efficiently.
D. . METABOLISM AND SIZE OF ORGANISMS
Standing Crop Biomass (expressed in terms of the dry weight or total
calorie content of an organism at a time) can be sustained by a constant flow of
energy in the food chain and to some extent is influenced by the size of the
organism. The smaller the organism, the smaller the biomass that can be
supported at a particular food level of the ecosystem. On the other hand, the
larger the organism, the larger the standing crop biomass
Example:
Phytoplankton algae in a lake weighing only a few kilograms can have a
metaboilism similar to that of a large tree, as well as a few kilograms of
zooplankton metabolism balanced with the metabolism of a cow.
Metabolic rate can be measured by measuring the amount of O2 for respiration
or O2 produced by photosynthesis. The speed of metaboilism of an organism is
affected by the surface area of the organism's body. This is because the larger the
surface area of the body, the greater the heat radiation, and homoithermic
organisms have a higher metabolism than poiciothermic organisms. In plants, the
wider the leaves, the higher the metabolism. A large tree can be considered one
organism but can also be considered one organism per leaf
E. FOOD TIER STRUCTURE AND FOOD PYRAMID
The phenomenon of interaction in the food chain where energy will be
lost when there is a transfer from one food level to another and the relationship
between the size and the metabolic rate produced by the community has a certain
trophic structure that is characteristic of an ecosystem (lakes, forests, corals, and
so on)
The tofic structure can be described and measured by calculating the
standing crop per unit area, measuring the energy tied per unit area for a time at
a trophic level. An ecosystem can be said to be a community of its physical
environment, each of which can be applied to small and large units that interact
with each other between organisms and their environment. It is known that there
are two laws of thermodynamics, namely 1) that energy can change shape, cannot
be destroyed and created, 2) that there is no change in the form of energy that is
efficient. The flow of energy in nature or ecosystems is subject to these
thermodynamic laws.
By the process of photosynthesis, sunlight energy is captured by plants,
and converted into chemical energy or food stored in the plant's body. The
process of energy flow takes place with the existence of a food chain process.
Plants are eaten by herbivores, thus the food energy from the plants flows into
the herbivorous body. Herbivores are eaten by carnivores, so the food energy
from herbivores enters the carnivore's body. In nature, the food chain is not
simple, but there are many interconnected or related to each other so that they
form food webs. Organisms that obtain food energy from plants with the same
number of steps are put into the same trophic level. The higher the trophic level,
the higher the ecological efficiency.
A living organism will always need other organisms and its environment.
The relationship that occurs between individuals and their environment is very
complex, mutually influencing or reciprocal. The reciprocal relationship
between living and non-living elements forms an ecological system called an
ecosystem. Within the ecosystem there is a food chain, energy flow, and
biogeochemical cycle
The food chain is the transfer of energy from its source in plants through a
series of eating and eating organisms. Ecological scientists recognize three types
of tree chains, namely predator chains, parasitic chains, and saprophytic chains.
1. Predator Chain
The main anchor predator chain is green plants as producers. The predator
chain starts from herbivorous animals as the first consumer, continues with
carnivorous animals that prey on herbivores as the 2nd consumer and ends in
carnivorous and herbivorous predators as the 3rd consumer
2. . Parasite Chain
The parasite chain starts from large organisms to organisms that live as
parasites. Examples of parasitic organisms include worms, bacteria, and
worms.
3. Saprophytic Chain
The saprophytic chain starts from the dead organism to the decomposing
body. For example, fungi and bacteria. The above chains do not stand alone
but are related to each other so that they form the pharynx of food.
4. Food Chain and Trophic Levels
One of the ways a community interacts is with eating and being eaten,
resulting in the transfer of energy, chemical elements, and other components
from one form to another along the food chain.
Organisms in ecological groups involved in the food chain are classified
in trophic levels. Trophic levels are composed of all organisms in the food
chain that are numbered equally in the eating level.
The source of energy is the sun. Plants that produce sugar through
photosynthesis only use solar energy and C02 from the air. Therefore, the
plant is classified in the first trophic level. Herbivorous animals or organisms
that feed on plants are members of the second trophic level. Carnivores that
directly feed on herbivores belong to the third trophic level, while carnivores
that feed on carnivores at the trophic level three belong to the fourth trophic
tier
5. Organic Pyramid
Trophic structures in ecosystems can be presented in the form of
ecological pyramids. There are 3 types of ecological pyramids, namely the
number pyramid, the biomass pyramid, and the energy pyramid.
The trophic structure and trophic function can be described by the ecological
pyramid. There are three ecological pyramids, namely:
a. Pyramid of numbers
Organisms with trophic levels can be presented in the pyramid of
numbers, such as we organisms at the first trophic level are usually the
most abundant, while organisms at the second, third, and subsequent
trophic levels are decreasing. It can be said that in most normal
communities, the number of plants is always more than that of herbivore
organisms. Similarly, the number of herbivores is always more than the
number of level 1 carnivores. Tier 1 carnivores are also always more
numerous than tier 2 carnivores. The pyramid of this number is based on
the number of organisms at each trophic level.
b. Biomass pyramid based on total dry weight or caloric value
Often a simple number of pyramids is not helpful in demonstrating
the flow of energy in an ecosystem. A more realistic depiction can be
presented with a biomass pyramid. Biomass is a measure of the weight of
living matter at a given time. To measure biomass at each trophic level,
the average weight of organisms at each level must be measured and then
the number of organisms at each level is estimated. The biomass pyramid
serves to describe the mass blend of all organisms in a given habitat, and
is measured in grams. To avoid habitat damage, usually only a few
samples are taken and measured, then the total of all biomass is
calculated. With measurements like this, more accurate information about
what is happening in the ecosystem will be obtained.
c. An energy pyramid that is based on the speed of energy flow or
productivity at the trophic level.
Often the biomass pyramid does not always provide the information
we need about a particular ecosystem. It is different from the energy
pyramid which is made based on observations made over a long period of
time. Energy pyramids are able to provide the most accurate picture of the
flow of energy in an ecosystem. In the energy pyramid there is a
successive decrease in the amount of energy available at each trophic
level. The decrease in energy that occurs in each trophic occurs due to the
following:
• Only a certain amount of food is captured and eaten by the trophic
level afterwards.
• Some of the food eaten cannot be digested and is excreted as
garbage.
• Only a portion of the digested food becomes part of the organism's
body, while the rest is used as a source of energy.
The pyramid of numbers is not so fundamental to the tool of illustration
because of the relative effects of:
• Geometry factors (size, size, small)
• Food chain (there is always energy lost transfer time). Therefore
the pyramid of numbers varies greatly.
The biomass pyramid is more fundamental as an illustration tool
because geometric factors have no effect. In general, the biomass
pyramid provides an overall picture of the effects of the food chain in
the ecosystem. The total weight of individuals and the sequential food
levels will describe a pyramid with a cascading slope as long as the
weight of the organism does not differ much.
However, if the lower organism is much smaller, an inverted biomass
pyramid will be produced. For example, very small producers and large
consumers, at some point the total weight of consumers is greater than
that of producers, this is because in summer the biomass of
phytoplankton is high, but in winter the biomass of phytoplankton is
small. Please keep in mind small producers, high turnover because they
breed quickly.
Generalization:
• . In terrestrial and shallow water ecosystems, producers are
generally large and live for a long time so that the shape of the
pyramid is normal (rice bottom and top are small).
• In open and deep bodies of water, generally small producers
and fast life cycles (high turn-overs), the biomass pyramid at
any given time varies and can be in the form of an inverted
pyramid.
• Small lakes where plants have roots and plankton are
important then the biomass pyramid is a transition of a and b
From the description above, it can be concluded that the image of
the inverted pyramid is an energy pyramid because it provides an
inverted picture of the functions of nature because the number and
weight of organisms that can be supported depend on the speed of
production. The energy pyramid provides an overview of the energy
flow in the food chain and the shape of the pyramid is not affected by
the number and weight of organisms. The shape of the energy pyramid
is always a large bottom and a small top. Ecological rules on the
pyramid in the ecosystem :
• The pyramid of numbers is too concerned with small organisms.
• The biomass pyramid is too concerned with large organisms.
• The energy pyramid provides an appropriate index in comparing
all components of the ecosystem.
