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Global change, global trade, and the next wave of plant invasions Author(s): Bethany A Bradley, Dana M Blumenthal, Regan Early, Edwin D Grosholz, Joshua J Lawler, Luke P Miller, Cascade JB Sorte, Carla M D'Antonio, Jeffrey M Diez, Jeffrey S Dukes, Ines Ibanez and Julian D Olden Source: Frontiers in Ecology and the Environment, Vol. 10, No. 1 (February 2012), pp. 20-28 Published by: Ecological Society of America Stable URL: http://www.jstor.org/stable/41479982 Accessed: 02-06-2015 21:33 UTC

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Bethany A Bradley1*, Dana M Blumenthal2, Regan Early3, Edwin D Grosholz4, Joshua J Lawler5, Luke P Miller6, Cascade JB Sorte7, Carla M D'Antonio8, Jeffrey M Diez9, Jeffrey S Dukes10, Ines Ibanez9, and Julian D Olden11

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a new generation of invasive species may be at our doorstep. Here, we review trends in the horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many from tropical and semiarid Africa as well as the Middle East. Risk assessment strategies have proven successful elsewhere at identi- fying and preventing invasions, although some modifications are needed to address emerging threats. Now is the time to implement horticulture import screening measures to prevent this new wave of plant invasions.

Front Ecol Environ 2012; 10(1): 20-28, doi:10.1890/l 10145 (published online 2 Dec 201 1)

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of gardening center to realize the enormous array of plant choices available to the everyday American gar- dener. Unfortunately, this wealth of consumer choices comes at a steep cost. Non-native plants introduced through the horticulture trade often become invasive (Mack and Lonsdale 2001; Reichard and White 2001), which we define here as introduced species whose popu- lations are surviving and reproducing beyond the loca- tion of introduction (sensu Blackburn et al 2011). Although only a portion of species that become invasive cause ecological damage (Williamson and Fitter 1996; Sax et al 2002), and some have benefited biodiversity (Davis et al 201 1 ; Schlaepfer et al 201 1 ), invasive plants as a whole substantially reduce native species abundance and diversity (Vilà et al 2011) and alter ecosystem func-

1 Department of Environmental Conservation, University of Massachusetts , Amherst , MA *( [email protected]); 2Range - land Resources Research Unit , US Department of Agriculture (USD A) Agricultural Research Service , Fort Collins, CO; 3 Cátedra Rui N abeiro, Universidade de Évora, Évora, Portugal; (continued on p28)

tion (Ehrenfeld 2010; Vilà et al 2011). Several well- known invasive plants in the US were deliberately intro- duced, including kudzu (Puer aria lobata; planted to stabi- lize soil), oriental bittersweet (Celastrus orbiculatus ; planted for aesthetics), purple loosestrife (Ly thrum sali- caria; planted for aesthetics), and tamarisk (Tamarix spp; first planted for aesthetics and later to act as wind breaks). Indeed, Mack and Erneberg (2002) estimated that over 60% of established, non-native species in the US were deliberately introduced. Moreover, the intro- duction process can select for species more likely to become invasive, because traits useful in horticulture - such as rapid establishment, broad climatic tolerance, and high resource allocation to flowers - can also increase invasiveness (Mack 2005). Global change is already aiding the spread of invasive species and increas- ing their ecological impacts (Dukes and Mooney 1999; Bradley et al 2010a). As global change proceeds, how- ever, it will influence not just the success of introduced plants but the introduction process itself (Hellmann et al 2008). Gardeners are poised to plant new species from warmer regions, as earlier onset of spring (Schwartz et al 2006) and warmer temperatures decrease the require- ment for winter-hardiness in ornamental plants (Arbor Day Foundation 2006). Similarly, as human populations increase in the arid and semiarid regions of the world, such as the American Southwest (Mackun and Wilson 2011), demand for drought- tolerant plants is expanding - a trend likely to accelerate in areas where climate change exacerbates drought (eg Seager and Vecchi 2010). At the same time, economic globalization offers opportunities to import new types of plants from previ- ously untapped parts of the world. Here, we review how global changes in trade and climate could influence sup- ply and demand for introduced ornamental plants. We predict the consequences for future plant invasions in

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In a nutshell: • New horticultural trading partners supply novel species that may become invasive

• Increasing demand for drought-tolerant species promotes the introduction of invasive species in dryland regions

• Gardeners are likely to plant new species as soon as rising temperatures allow, favoring the assisted migration of intro- duced species relative to non-horticultural natives

• Emerging trade supply coupled with shifting demand due to climate change makes the US susceptible to a new array of invasive plants

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BA Bradley et al. Invasion risk from horticulture and climate change

the conterminous US and conclude with a review of pol- icy changes that could mitigate this new generation of invasions.

■ Supply: identifying emerging trading partners

There is a clear link between increasing amounts of trade and abundance of invasive plant species (Westphal et al 2008; Hulme 2009). In Europe and North Africa, mone- tary values of imports were one of the best predictors of invasive plant abundance (Vilà and Pujadas 2001), and in the UK, plants more widely available in 20th-century nurseries were more likely to be invasive today (Dehnen- Schmutz et al 2007). As the number of horticultural trad- ing partners with the US ("source" countries) continues to rise, so too will the number of introductions of non- natives that will later become invasive and potentially problematic (Hulme 2009). Moreover, the rate of intro- duction of future invasive species is steepest in the early stages of new trade partnerships, due to the sheer volume of novel introductions (Figure 1; Levine and D'Antonio 2003), and may contribute to an "invasion debt" that will be realized decades in the future (Essi et al 2011). As trade partners become established and novel introduc- tions slow, the number of invasive plants emerging from the trading partnership may still rise, but largely as a result of the persistent increase in propagule pressure (Lockwood et al 2005) as more and more individuals of a given species are planted throughout the landscape. The greatest risk of new invasive plants arriving in the US is therefore likely to come from emerging trade partners.

We identified emerging and established sources of nurs- ery plant imports to the US using the US Department of Agriculture's (USDAs) global agricultural trade system online database (USDA 2011). Nursery product cate- gories assessed included bulbs and roots, trees and shrubs, herbaceous perennials, unrooted vines, and mosses and lichens, but excluded any plant identified by name (eg azaleas). We compiled import dollar value by country from 1989 (the first year of record) through 2010 (all dollar amounts hereafter are in US$). We defined "emerging" trade partners as countries with an increasing trend during the period of record, but an average import value of less than $100000 per year from 2000-2010. "Established" trade partners had an average import value of greater than $100 000 per year from 2000-2010. This threshold divided the pool of nursery plant trade partners roughly in half. We then determined whether invasive plants have arrived from predominantly emerging or established trade partners by assessing the countries comprising the native ranges for 2608 invasive plants in the US as documented by the USDA (USDA ARS 2011; USDA NRCS 2011).

We identified a total of 42 emerging trade partners, clus- tered mainly across tropical regions, the Middle East, and Eastern Europe (Figure 2a). Global imports of unnamed (ie non- varie tal) nursery plants were valued at more than $250 million in 2010; only $4 million of those imports

Figure 1 ♦ New influxes of non-native invasive species are most prominent in the early stages of new trade partnerships . With established trade partners , invasions continue to rise with increase in trade, but at a slower rate. Adapted from Levine and D'Antonio (2003).

were from emerging trade partners. However, imports from emerging trade partners are on the rise as compared with those from established partners: trade value from emerging sources rose by 69% from 2000-2010, while imports from established sources declined by 9% over the same period.

The average invasive plant in the US had only 29% of its native range in emerging countries (Figure 2b) versus 54% in established countries (Figure 2c), supporting pre- vious findings that more trade leads to more invasive species (Vilà and Pujadas 2001; Levine and D'Antonio 2003; Westphal et al 2008). In addition, more than a quarter of invasive plants in the US have native ranges that do not include any emerging trade partners (Figure 2b). The low contribution of emerging trade partners to the current complement of invasive plants in the US implies that there is considerable scope for further inva- sive species introductions from these countries.

■ Demand: xeriscaping and invasion of dryland regions

Although drylands can be heavily impacted by invasive species, the number of species that have invaded such sys- tems is low when compared with that in more mesic regions (Figure 3a). Furthermore, within dryland regions, many invasive species are restricted to relatively wet areas (Stohlgren et al 1998). The limited number of invasive species established in dryland regions is probably due to a combination of historically low human population den- sity - and therefore lower propagule pressure (Lockwood et al 2005) - and historical preferences for species from

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Invasion risk from horticulture and climate change BA Bradley et al.

Figure 2. Currently emerging and established horticultural trade partners , and contributions of those trade partners to US invasive plants, (a) Emerging partners (shown in red) currently average less than $100000 yr~l in trade value , but imports are increasing. Established partners (shown in blue) currently average more than $100000 yr

~l in trade value, (b) Relatively few of the current invasive plant species in the US are native to emerging trade regions, (c) Many of the current US invasive plants are primarily native to established trade regions.

mesic environments (Hilaire et al 2008). Both of those trends are changing. Rapidly expanding human popula- tions in dryland areas (Mackun and Wilson 2011) have not only created new gardens and planted more non- native species, but in the process have also had to con- tend with limited water supplies (Palmer et al 2008). In many areas, particularly those at lower latitudes, climate change is expected to further reduce water available for human use (Palmer et ai 2008; Seager and Vecchi 2010). Water limitations have already led to restrictions on

water use for gardening and greater use of drought-toler- ant species for landscaping in the US (Figure 3b; Hilaire et ai 2008).

A large portion of residential water use in dryland regions is directed toward lawn and garden maintenance (eg 30-40% in California; Gleick 1996). Xeriscaping - the use of drought-tolerant plants in landscaping - can reduce that water use by as much as 76% (Sovocool et al 2006). Furthermore, because many of the aesthetic con- siderations determining the appeal of xeriscapes depend

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№ Sources of nursery plant imports to the US

Emerging sources Established sources Annual import value 2000-2010 (x $1000) Annual import value 2000-2010 (x $100000) i - i Not a source <0.5

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that are emerging that are established

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BA Bradley et al. Invasion risk from horticulture and climate change

Figure 3 ♦ Expansion of xeriscaping demand could generate new species introductions, (a) The floras of the West and Southwest deserts - the areas most likely to receive new , water-tolerant ornamental species - currently have the smallest percentages of introduced plant species, (b) A xeriscaped yard in the Sonoran Desert with predominantly introduced species native to the Chihuahuan Desert in Mexico, (c) A survey of nine nursery catalogs revealed that most species marketed as "drought- tolerant" are introduced. One nursery specializing in drought-tolerant species increased its selection of species between 2000 and 2011; encouragingly, most of the new species were natives.

on the types of plants used (Hilaire et al 2008), accep- tance of xeriscaping could increase as the availability and variety of drought-tolerant species grows. Unfortunately, increasing the availability and variety of non-native, drought- tolerant species could also increase the probabil- ity of introducing species capable of invading dryland regions.

To quantify the potential of xeriscaping as a source of new invasive plants, we tabulated the number of plants being marketed for this practice. First, we identified nine nurseries in the US that advertise more than ten "xeriscape", "drought-tolerant", or "water-wise" plant species (henceforth collectively referred to as "drought- tolerant" species). Using the USDA PLANTS Database (USDA NRCS 2011) and other online sources, we then identified the origin (native or introduced) of 731 drought-tolerant species (Figure 3c). We found that more than half (401) of the drought-tolerant species were non- native, suggesting that many species that, in the future, will become invasive in dryland regions of the US may already have arrived and are increasingly being planted.

To explore how the xeriscaping industry may be chang- ing, we requested catalogs from previous years from our nine nursery sources, but received catalogs from only one, a nursery that specializes in drought-tolerant plants. For this source, we tabulated the number of native and intro- duced drought-tolerant species by year. We found that while the nursery expanded its drought-tolerant species offerings by 37% between 2005 and 201 1, almost all of the newly offered species were native to the US (Figure 3c).

This is a somewhat encouraging trend. Together with the wide availability of native drought-tolerant plants (330) available across sources, it suggests considerable potential to supply the xeriscaping demand with US native species. Although these species may not be native to the particular US deserts in which they are planted, species introduced from one North American region to another are seldom reported as becoming problematic invaders (Mueller and Hellmann 2008). Thus, the focus on US native plants by the xeriscaping industry may help prevent detrimental intercontinental invasions.

■ Demand: shifting hardiness zones and the American gardener

In addition to the specific demands for drought-tolerant species, climate change could stimulate an overall increase in the demand for new horticultural species that thrive in new, warmer climates. Rising temperatures are already causing US "hardiness zones" (temperature iso- clines defined by the USDA) to shift (Arbor Day Founda-

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2 CD w

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Invasion risk from horticulture and climate change В A Bradley et al.

Figure 4 ♦ Climate change is likely to shift hardiness zones northward and upward in elevation , increasing the land area in warm zones and altering demand for horticulture species, (a) Hardiness zones in the US, based on average climate from 1961-1990 and based on projected average climate from 2040-206 9 (color scheme after that of Arbor Day Foundation 2006). (b) Change in land area of hardiness zones, (c) Total land area in each hardiness zone by 2040-206 9.

tion 2006) and the growing season to lengthen (Schwartz et ai 2006). The horticulture industry is likely to expand the array of available species in expectation of, and in response to, this new consumer demand (Figure 3c). Building on the analysis of updated hardiness zones (Arbor Day Foundation 2006), we explored how projected changes in climate will affect the distribution of plant har- diness zones over the next 40 years and how shifts in the land area of hardiness zones might influence demand.

Hardiness zones are regions delineated by average mini- mum annual temperatures that provide gardeners and landscape designers with guidance on which plants can be grown in which parts of the US (Cathey 1990). We mapped current hardiness zones using the PRISM (Parameter-elevation Regressions on Independent Slopes Model) 4-km resolution average temperature dataset from 1961-1990 (Daly et al 2004) classified into 5.6°C bins defined by the USDA (Cathey 1990). To match the spa-

tial resolution of projected future climate, we aggregated the PRISM data to 0.125° spatial resolution (approxi- mately 12 km2 in the US). We mapped potential future hardiness zones using averaged projections from 16 differ- ent general circulation models run for a mid-high (Special Report on Emissions Scenarios [SRES] A2) greenhouse- gas emissions scenario for the period from 2040-2069. Statistically downscaled climate projections at 0.125° res- olution were provided by the Climate Wizard project (Girvetz et al 2009). For mapping both the current and projected future hardiness zones, we calculated annual minimum temperatures using average temperature of the coldest month based on an empirical relationship between the two (Prentice et al 1992).

Hardiness zones in the US are likely to shift substan- tially northward over the next 40 years (Figure 4a). This will result in an expansion of the warmer zones (particu- larly zones 6 and 8-11), a contraction of some of the

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BA Bradley et al. Invasion risk from horticulture and climate change

cooler zones (zones 3-5), and the near-complete loss of zone 2, currently the coldest zone in the conterminous US (Figure 4b). With concerted planting efforts, gardeners are already helping garden plants to shift their geographic dis- tributions into newly suitable climatic regions ahead of non-propagated species (Van der Veken et al 2008). Many invasive species are unintentionally taken along for the ride (Maki and Galatowitsch 2004), whereas others are actively planted in regions forecast to become suitable for invasion with climate change (eg Bradley et al 2010b). Unless assisted migration is also used for native species (Richardson et al 2009), these trends raise the prospect that both existing and new invasive species may be better able to shift their ranges to align with new climatic condi- tions, pre-empting and possibly precluding the establish- ment of native species. Of further concern for invasive species biologists and managers are the novel sets of species that could be introduced in response to increasing demand for heat-tolerant species: warm hardiness zones 8 and 9 are projected to expand by 45% and 120%, respec- tively, and are likely to cover a substantial portion of US land area by 2050 (Figure 4c). In regions such as these, the performance of many native species will be compromised as the climate warms beyond species' current tolerance (Walther 2004). Introducing non-native species that are pre-adapted to the new climatic conditions in these regions, and can thus outperform native species, further increases the odds of invasion.

■ The intersection of supply and demand

The intersection of emerging supply and demand forces creates considerable motivation for novel species intro- ductions and poses the greatest risk for a new wave of plant invasions into the US (Figure 1). Emerging trade partners (and sources of novel species) included clusters of nations in warm tropical regions and several arid regions of the Middle East and Africa (Figure 2). At the same time, demand for new species is increasing in dry- land regions and is also likely to expand in warmer US hardiness zones (Figure 4).

To test how emerging supply and demand might over- lap, we created a map of global hardiness zones at 10-arc- minute resolution using the same criteria as for the US hardiness zones. Species are generally expected to become naturalized in areas with similar climatic conditions to that of their native range (eg Thuiller et al 2005). Indeed, the hardiness zones where non-native species have become naturalized in the US have historically tended to match their native hardiness zones (see WebPanel 1 and

WebFigure 1), so it is reasonable to expect this trend to continue in the future. We therefore explored the degree of matching between future climatic conditions in the US (2050, represented by mean conditions between 2040 and 2069) and historical conditions in established and emerg- ing trade partners (represented by mean conditions between 1961 and 1990). We used historical conditions in source countries based on the assumption that plants selected for the horticulture trade are adapted to historical climatic conditions in their source countries. The hardi- ness zones of emerging trade partners are strongly skewed toward warmer climates (higher hardiness zone numbers; Figure 5a), even more so than those of established trade partners. The land area of source countries in zones 6-10, which collectively represent the greatest increase in future US land area, increases by 31% with the addition of emerging trade partners. These emerging partners also tend to be in drier parts of the world (Figure 5b). Although established trading partners already include large areas with relatively low precipitation, source-coun- try land area receiving less than 20 cm of precipitation per year - equivalent to climates such as those of Las Vegas, Nevada and Phoenix, Arizona - increases by 44% with the addition of emerging trade partners. These patterns suggest that emerging plant trade partners are well poised

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Figure 5» Supplies of novel species from emerging trade partners could meet increasing demand for species adapted to warm and dry environments . (a) Current hardiness zones of emerging source countries are skewed toward warmer climates, (b) Current mean annual precipitation of emerging source countries includes some of the driest areas on Earth.

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Invasion risk from horticulture and climate change BA Bradley et al.

to supply the very drought- and heat-tolerant species that nurseries in the US are, or will soon be, looking to sell. We predict that the strong overlap of emerging supply and emerging demand could lead to a sharp rise in introduc- tions of new invasive species (Figure 1).

■ Management, policy, and stakeholder solutions

Identifying invasive plants before they arrive is crucial for preventing damage to native biodiversity. Post- introduc- tion control of established species may not repair the desired ecosystem functions because invasive species, combined with other elements of global change, may have already altered biotic interactions (Schlaepfer et ai 2011). Currently, under the US Plant Protection Act (Public Law 106-224), plant importation conforms to a "Black List", which labels plants as "prohibited" or "restricted" after they are proven harmful. This policy is akin to closing the barn door after the horse has bolted, however, and will prove particularly ineffective if, as we predict, changing supply and demand forces facilitate a new generation of introductions. In contrast, "Green List" (or "White List") approaches - based on weed risk assessments (WRAs) - have been used in countries such as Australia and New Zealand (Perrings et al 2005). Predictors of invasive plants include whether the species has a history of invasion elsewhere, climate matching, and reproduction and dispersal strategies (Pheloung et al 1999). WRA scores have repeatedly been shown to have good predictive power for separating out invasives from the array of horticultural import species (see examples in McClay et ai 2010) and provide a clear economic benefit (Keller et ai 2007). The Animal and Plant Health Inspection Service (APHIS) branch of the USDA has proposed a new rule for plant imports that would add the category "NAPPRA" ("Not authorized pending pest risk analysis") to the Plant Protection Act (USDA APHIS 2009). The NAPPRA rule would require APHIS to per- form a WRA at the request of plant importers on taxa that have previously not been imported, and then deter- mine whether the plant should be accepted or prohibited (USDA APHIS 2009). If implemented, this rule would represent a major positive step in the long-term preven- tion of new invasive species.

One concern with WRA efficacy - in light of emerging, novel invasives - arises because a major component of risk assessment considers whether the species has a his- tory of invasion elsewhere (Pheloung et al 1999). Emerging US trade partners are unlikely to have long- established trade relations with other parts of the world, so the invasiveness of species supplied by these partners will be unknown. This lack of information should not be mistaken for a lack of invasiveness, and WRAs will have to be adjusted accordingly for emerging trade partners. In addition, the climate-matching criteria of WRAs should be applied to both current and future climate conditions of the recipient region.

The US horticulture industry is among the most impor- tant players in the prevention of future invasions, and increasing awareness of invasive species among nursery professionals is a critical step. The St Louis Declaration (Baskin 2002) made an important contribution toward identifying ways the horticulture industry can help, but the information has reportedly not reached industry pro- fessionals (Burt et al 2007). The voluntary codes of con- duct in the Declaration would reduce invasions by encouraging nursery professionals to assess invasive potential of new plants before selling them and to pro- mote native species in breeding programs. Many nursery professionals will discourage customers from planting known invasive species and will phase out plants known to be invasive but often lack information on which species are problematic (Burt et ai 2007). Links between invasive plant managers and the horticulture industry need to be strengthened to promote better dissemination of that information (D'Antonio et ai 2004; Peters et al 2006). The trade in drought-tolerant species - which is ultimately driven by environmental concerns (Hilaire et al 2008) but presents novel environmental risks for dry- land regions (Figure 3) - may afford a particularly good opportunity for education. Preferential use of species for xeriscaping that are native to the US, and especially to the region of planting, would greatly reduce propagule pressure from non-native species. This move might be attractive to environmentally conscious gardeners and horticultural companies.

Finally, the horticulture industry can take proactive steps to aid risk assessment and prevention, such as providing needed information to WRAs based on field trials and identifying and ceasing production of plants that escape cultivation easily (Mack 2005). Furthermore, the horticul- ture industry can help fight range expansion of invasive plants by stopping the sale of plants known to be invasive elsewhere in the US. Collaborative groups involving repre- sentatives from the horticultural industry, nursery and landscape organizations, regulatory agencies, and non-gov- ernmental organizations are now working toward limiting the sales of invasive plants, in part by developing lists of non- invasive alternatives (eg Cal-HIP 2004).

■ Conclusions

Many lines of evidence suggest that global change will, on average, increase risk of plant invasion (Dukes and Mooney 1999; Bradley et ai 2010a). Here, we identify another risk - one that policy can effectively address. Climate change is likely to increase demand for drought- and heat-tolerant landscaping plants in the US. Emerging trade partners have warm, dry climates that are well matched to this future demand and could supply many new and potentially invasive species. This emerg- ing threat intensifies the need for preemptive screening of nursery stock species prior to import. Although the num- bers and abundance of invasive species already in the US

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BA Bradley et al. Invasion risk from horticulture and climate change

might engender complacency, we suggest that active management of new invasion risks will remain important well into the future.

■ Acknowledgements

Many thanks to M McCutchen for help compiling data on drought- tolerant species and to S Jones for early dis- cussions. E Brusati and M Smith provided helpful com- ments on earlier versions of this manuscript. This review was conducted as part of the Climate & Invasions Working Group with support provided by the National Center for Ecological Analysis and Synthesis, a Center funded by the National Science Foundation (grant #EF- 0553768), the University of California, Santa Barbara, and the State of California. We gratefully acknowledge the modeling groups, the Program for Climate Model Diagnosis and Intercomparison (PCMDI), and the World Climate Research Programme's (WCRP's) Working Group on Coupled Modelling (WGCM) for their roles in making available the WCRP Coupled Model Intercomparison Project 3 (CMIP3) multi-model dataset. Support of this dataset is provided by the Office of Science, US Department of Energy.

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department of Environmental Science and Policy , University of California , Davis, Davis, CA; 5 School of Forest Resources, University of Washington, Seattle, WA; 6M arine Science Center, Northeastern University, Nahant, MA; 7 Department of Environmental, Earth and Ocean Sciences, University of Massachusetts, Boston, MA; 8Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA; 9 School of Natural Resources, University of Michigan, Ann Arbor, MI; l0Department of Forestry and Natural Resources and Department of Biological Sciences, Purdue University, West Lafayette, IN; 11 School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA

www.frontiersinecology.org © The Ecological Society of America

Assistant Professor of Plant Pathology

Microbial Invasive Species, University of California, Riverside

The Department of Plant Pathology and Microbiology invites applications for a 9-month tenure-track faculty position (research and teaching in the Agricultural Experiment Station), emphasizing the invasion and impacts of microbial (such as bacteria, fungi, viruses) pathogen or symbiont species into agricultural or wildland ecosystems. Applicants studying microbes that regulate invasive plants will also be considered. Approaches could include genetics, genomics, population ecology/evolution, biochemical, bioinformatics, ecoinformatics and/or modeling. The successful candidate will join a vibrant community of researchers studying microbe-host and microbe-environment interactions, have opportunities to collaborate with researchers in UC's Division of Agriculture and Natural Resources, the Center for Conservation Biology, the Center for Invasive Species Research, the Institute for Integrative Genome Biology, and have access to modern campus facilities in genomics, proteomics, microscopy, ecological sensing technologies and field stations and facilities.

Consult WWW.plantpath.ucr.edu for details about the department. Applicants will be expected to pursue vigorous, extramurally funded research and contribute to undergraduate and graduate teaching in Programs in Microbiology, Plant Pathology, or Genetics, Genomics and Bioinformatics. A Ph.D. and demonstrated excellence in research are required.

Email curriculum vitae, statements of research and teaching interests, selected reprints, and three letters of reference to: Dr. James Borneman, c/o Tiffany Lindsey, Department of Plant Pathology and Microbiology,

University of California, Riverside, California 9252 1-04 15. Email: [email protected]

Evaluation of applications will begin February 17, 2012, but the position will remain open until filled. Position will be available July 1, 2012.

UNIVERSITY OF CALIFORNIA The University of California is an Affirmative I I Щ Ш I V Я ■

1 m I Action/Equal Opportunity Employer. Ill I ШЯ ■"* III I®

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