Climate Change Adaptation Strategies for Resource...

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THE YEAR IN ECOLOGY AND CONSERVATION BIOLOGY, 2009 Climate Change Adaptation Strategies for Resource Management and Conservation Planning Joshua J. Lawler College of Forest Resources, University of Washington, Seattle, Washington Recent rapid changes in the Earth’s climate have altered ecological systems around the globe. Global warming has been linked to changes in physiology, phenology, species distributions, interspecific interactions, and disturbance regimes. Projected future cli- mate change will undoubtedly result in even more dramatic shifts in the states of many ecosystems. These shifts will provide one of the largest challenges to natural resource managers and conservation planners. Managing natural resources and ecosystems in the face of uncertain climate requires new approaches. Here, the many adaptation strategies that have been proposed for managing natural systems in a changing climate are reviewed. Most of the recommended approaches are general principles and many are tools that managers are already using. What is new is a turning toward a more agile management perspective. To address climate change, managers will need to act over different spatial and temporal scales. The focus of restoration will need to shift from historic species assemblages to potential future ecosystem services. Active adaptive management based on potential future climate impact scenarios will need to be a part of everyday operations. And triage will likely become a critical option. Although many concepts and tools for addressing climate change have been proposed, key pieces of information are still missing. To successfully manage for climate change, a better un- derstanding will be needed of which species and systems will likely be most affected by climate change, how to preserve and enhance the evolutionary capacity of species, how to implement effective adaptive management in new systems, and perhaps most importantly, in which situations and systems will the general adaptation strategies that have been proposed work and how can they be effectively applied. Key words: adaptation; adaptive management; climate change; conservation planning; management; scenario planning; triage Introduction Over the past century, global average annual temperatures have risen 0.7 C (IPCC 2007b). In the Arctic, temperatures have risen at ap- proximately twice that rate. This trend is very likely to continue into the future, as global aver- age surface temperatures are projected to rise between 1.1 and 6.4 C by 2100, and temper- atures at the high northern latitudes are pro- Address for correspondence: Joshua J. Lawler, College of Forest Re- sources, University of Washington, Box 352100, Seattle, WA 98105. [email protected] jected to rise between 3 and 12 C by the end of the century (IPCC 2007b). Precipitation pat- terns are also projected to change, although the direction, magnitude, and confidence sur- rounding precipitation projections vary by re- gion and season. These changes have profound implications for the Earth’s natural systems. Recent climatic changes have been linked to decreases in snow- pack (Groisman et al. 2001; Mote 2003), in- creases in the frequency and severity of large wildfires (Westerling et al. 2006), and rising sea levels (IPCC 2007b). These changes in turn have the potential to alter the timing and magnitude of stream flows, the structure and The Year in Ecology and Conservation Biology, 2009: Ann. N.Y. Acad. Sci. 1162: 79–98 (2009). doi: 10.1111/j.1749-6632.2009.04147.x C 2009 New York Academy of Sciences. 79

Transcript of Climate Change Adaptation Strategies for Resource...

THE YEAR IN ECOLOGY AND CONSERVATION BIOLOGY, 2009

Climate Change Adaptation Strategiesfor Resource Managementand Conservation Planning

Joshua J. Lawler

College of Forest Resources, University of Washington, Seattle, Washington

Recent rapid changes in the Earth’s climate have altered ecological systems around theglobe. Global warming has been linked to changes in physiology, phenology, speciesdistributions, interspecific interactions, and disturbance regimes. Projected future cli-mate change will undoubtedly result in even more dramatic shifts in the states of manyecosystems. These shifts will provide one of the largest challenges to natural resourcemanagers and conservation planners. Managing natural resources and ecosystems inthe face of uncertain climate requires new approaches. Here, the many adaptationstrategies that have been proposed for managing natural systems in a changing climateare reviewed. Most of the recommended approaches are general principles and manyare tools that managers are already using. What is new is a turning toward a more agilemanagement perspective. To address climate change, managers will need to act overdifferent spatial and temporal scales. The focus of restoration will need to shift fromhistoric species assemblages to potential future ecosystem services. Active adaptivemanagement based on potential future climate impact scenarios will need to be a partof everyday operations. And triage will likely become a critical option. Although manyconcepts and tools for addressing climate change have been proposed, key pieces ofinformation are still missing. To successfully manage for climate change, a better un-derstanding will be needed of which species and systems will likely be most affectedby climate change, how to preserve and enhance the evolutionary capacity of species,how to implement effective adaptive management in new systems, and perhaps mostimportantly, in which situations and systems will the general adaptation strategies thathave been proposed work and how can they be effectively applied.

Key words: adaptation; adaptive management; climate change; conservation planning;management; scenario planning; triage

Introduction

Over the past century, global average annualtemperatures have risen 0.7◦C (IPCC 2007b).In the Arctic, temperatures have risen at ap-proximately twice that rate. This trend is verylikely to continue into the future, as global aver-age surface temperatures are projected to risebetween 1.1 and 6.4◦C by 2100, and temper-atures at the high northern latitudes are pro-

Address for correspondence: Joshua J. Lawler, College of Forest Re-sources, University of Washington, Box 352100, Seattle, WA [email protected]

jected to rise between 3 and 12◦C by the end ofthe century (IPCC 2007b). Precipitation pat-terns are also projected to change, althoughthe direction, magnitude, and confidence sur-rounding precipitation projections vary by re-gion and season.

These changes have profound implicationsfor the Earth’s natural systems. Recent climaticchanges have been linked to decreases in snow-pack (Groisman et al. 2001; Mote 2003), in-creases in the frequency and severity of largewildfires (Westerling et al. 2006), and risingsea levels (IPCC 2007b). These changes inturn have the potential to alter the timing andmagnitude of stream flows, the structure and

The Year in Ecology and Conservation Biology, 2009: Ann. N.Y. Acad. Sci. 1162: 79–98 (2009).doi: 10.1111/j.1749-6632.2009.04147.x C© 2009 New York Academy of Sciences.

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composition of vegetation communities, andthe nature of coastal systems. As temperaturesand sea levels continue to rise, many ecosys-tems will undergo significant changes. Coastalwetlands will be inundated, alpine zones willshrink, and some wetlands, ponds, and lakeswill dry up (IPCC 2007a).

Many ecological systems are already show-ing the effects of recent climatic changes(Walther et al. 2002; Parmesan and Yohe 2003;Root et al. 2003; Parmesan 2006). The mostwell documented changes include changes inphenology, species distributions, and physiol-ogy. Recent phenological changes have beenobserved in many different ecological systems(Sparks and Carey 1995). Spring events, for ex-ample, have been occurring 2.3 days earlierper decade over the last century (Parmesanand Yohe 2003). Plants are flowering and fruit-ing earlier (Cayan 2001), birds are laying eggsearlier (Brown et al. 1999; Crick and Sparks1999), and some amphibians are mating ear-lier (Beebee 1995; Gibbs and Breisch 2001).Changes in phenology have the potential todecouple interdependent ecological events, re-sulting in changes in species interactions, com-munity composition, and ecosystem function-ing (Stenseth and Mysterud 2002).

The paleoecological record indicates thatspecies have shifted their geographic rangesin the past in response to changes in climate(Brubaker 1989; Davis and Shaw 2001). Morerecent records indicate that species have alsoshifted their distributions in response to re-cent climate change. Many species of plants,birds, butterflies, and amphibians have shiftedtheir distributions in patterns and at rates thatare consistent with recent climatic changes(Parmesan 2006). In general, these species areshifting their ranges upward in elevation andpoleward in latitude (Parmesan et al. 1999;Thomas and Lennon 1999; Seimon et al. 2007;Lenoir et al. 2008). In a few cases, popula-tion and even species extinctions have been at-tributed to recent climatic changes (Pounds et al.

1999). As species move in response to climatechange, new communities will form, new inva-

sive species will emerge, and ecosystem func-tions will be altered.

Plants, corals, and other organisms haveclear physiological responses to climate change.Increased atmospheric CO2 concentrationscan result in increased water-use efficiency inplants. Because different species will responddifferently to increased CO2, differential in-creased water-use efficiencies will likely result inshifts in competitive relationships and changesin plant communities (Policy et al. 1993). Manycorals are extremely sensitive to changes in tem-perature. Increases of just a few degrees for evena short period can result in bleaching (a loss ofthe coral’s symbiotic zooxanthellae and theirphotosynthetic pigments). Extensive bleachingevents have occurred during the past 20 yearsin several regions around the globe (West andSalm 2003). Several species of fish also havewell-documented thermal thresholds for sur-vival at different life stages (e.g., McCullough1999; Moyle 2002). Even small changes in tem-perature have the potential to affect populationdynamics and habitat use for many species.

Managing natural systems in the face of suchwidespread change is a daunting task. Perhapsthe largest challenge for mangers is making de-cisions based on limited and often highly un-certain projections of future climate impacts(Lawler et al. in press-b). Over the past 10 to20 years, researchers have begun to suggestways that managers and planners can beginto address climate change. Here, I summa-rize these recommendations. I begin with anoverview of the general, largely conceptual, rec-ommended adaptation strategies. I go on todescribe some of the more specific suggestionsthat have been made for addressing climatechange in freshwater, marine, and terrestrialsystems. Although many of the recommendedapproaches for addressing climate change arealready used to manage resources and protectbiodiversity, effectively implementing these ap-proaches will require new perspectives. I con-clude with a brief discussion of the most press-ing research needs for successfully developingand implementing adaptation strategies.

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General Strategies for AddressingClimate Change

The vast majority of the proposed strategiesfor managing resources in a changing climateare general concepts. These concepts can beloosely grouped into three basic types of strate-gies: those promoting resistance, resilience, andchange (Millar et al. 2007). Resistance is the abil-ity of a system to remain unchanged in the faceof external forces. Resilience can be defined asthe ability of a system to recover from pertur-bations (Holling 1973). A resilient system willchange in response to external forces but willreturn to its original state. With respect to cli-mate change, systems that are more resilient arethose that are better able to adapt to changesin climate. Resilient systems will continue tofunction, albeit potentially differently, in an al-tered climate. Less resilient systems will likelyundergo messy transitions to new states, result-ing in the loss of ecosystem functioning, popu-lations, or even species. Strategies that promotechange are those designed to help move a sys-tem from one state to another. The most com-monly recommended strategies for promotingresistance, resilience, and change are brieflydiscussed below.

Removing Other Threats and ReducingAdditional Stresses

Perhaps the most obvious approaches to in-creasing resilience are the removal of other,non-climate-related threats to a species or sys-tem and reducing other stresses on species. De-creasing the impact of exotic species, habitatloss and fragmentation, overharvest, and otherthreats generally results in larger populationsthat will likely be better able to absorb per-turbations (Rogers and McCarty 2000; Noss2001; Soto 2001; Hansen et al. 2003). Not onlydo other threats reduce the ability of a popula-tion or system to respond to or to absorb newimpacts, but in many cases, climate change mayexacerbate the effects of other threats. For ex-ample, increases in temperature may increase

toxicity of pesticides or the infection rates andseverity of diseases (Kumaraguru and Beamish1981). Likewise climate change may increasecompetitive pressure from invasive species, assome invasive species may benefit from in-creased atmospheric CO2 concentrations orchanges in temperature or precipitation, allow-ing them to spread and/or outcompete nativespecies (Dukes and Mooney 1999; Schlesingeret al. 2001; Zavaleta and Royval 2001; Raheland Olden 2008).

Environmental stresses may also reducethe resilience of individuals and populationsto climate change. For example, Drosophila

melanogaster exposed to parasitic attacks whilein the larval stage were more susceptible todesiccation that those not exposed to para-sitic attacks (Hoang 2001). Similarly, streamsidesalamanders, Ambystoma barbouri, exposed to theherbicide atrazine were more susceptible todesiccation than were unexposed salamanders(Rohr and Palmer 2005). Removing or reduc-ing existing environmental stresses and threatsto populations or species will, in some cases,enhance their resilience to climate change.

Expanding Reserve Networks

Protected areas are arguably one of the bestways to conserve biodiversity. However, climatechange will challenge the ability of the currentreserve network to provide protection when theclimate shifts so much that plants and animalsno longer thrive where their current reservesare located (Peters and Darling 1985). Manyresearchers have suggested expanding reservenetworks to give systems and species room tomove and places to go (Halpin 1997; Shafer1999). Increasing redundancy in the reservenetwork can also increase resilience by provid-ing more opportunities in different places orchances in which species or communities mightpersist. Some have recommended increasingthe size of existing reserves, adding buffersaround existing reserves, and adding larger re-serves to reserve networks (Halpin 1997; Shafer1999; Noss 2001) (Fig. 1A). Larger reserves are

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Figure 1. Proposed strategies for augmenting existing reserve networks to address climatechange. Additional reserves can be placed (A) to enlarge existing reserves, (B) to spanclimatic or edaphic gradients, (C) to facilitate directional species movements in responseto increasing temperatures, and (D) to help connect existing reserves. Existing reserves arerepresented by darker shapes, and new reserves are represented by lighter shapes.

likely to preserve a greater diversity of envi-ronmental conditions and allow for movementwithin the reserve. Coastal systems in partic-ular will require large reserves that extendinland, allowing species to shift as sea levelsrise.

Simply developing more and larger reservesmight not be enough if they are not located inthe right places. One more strategic possibilityentails locating reserves so that they capture themost potential for habitat heterogeneity underany climate scenario. Such areas would coverdiverse topographic, edaphic, and hydrologicconditions (Halpin 1997). Placing large, longreserves across biotic transition zones such asecotones may allow for the continued protec-tion of that transition as it shifts with climatechange (Fig. 1B). Others have suggested plac-ing reserves at the poleward edge of speciesranges (Shafer 1999), arranging reserves longi-tudinally (Pearson and Dawson 2005) (Fig. 1C),

and placing new reserves between existing re-serves to facilitate connectivity (Fig. 1D).

Ideally, ecological forecasting could be usedto identify sites that would best protect biodi-versity in a changing climate (Hannah 2008).Dynamic global vegetation models (DGVMs;e.g., Cramer et al. 2001; Bachelet et al. 2003) andclimate-envelope models (Pearson and Dawson2003) have been used to assess the ability ofreserves or reserve networks to protect speciesunder different climate-change scenarios (Scottet al. 2002; Burns et al. 2003; Araujo et al. 2004).A few studies have used such models to sug-gest reserve networks that would be resilientto climate change. For example, Hannah et al.(2007) used climate-envelope models to projectspecies’ range shifts in three different regionsof the globe in response to climate change andthen selected reserves that adequately protectedthose species in the future. Likewise, Williamset al. (2005) used climate-envelope models to

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identify potential corridors that would allowmovement between current ranges and species’potential future ranges. Such approaches relyheavily on the ability of the models to pre-dict species’ responses to climate change. Givenboth the uncertainty in projected future cli-mates and the uncertainty inherent in mostrelevant ecological forecasting approaches (e.g.,Thuiller 2004; Lawler et al. 2006), use of thesemodels for the selection of reserves will require,at the very least, that meaningful uncertaintyestimates are evaluated in conjunction with, orincorporated into, the future projections. A sec-ond limitation of this approach is that data willbe lacking for the vast majority of biodiversity,and reserve selection based on this approach islikely to be biased toward well-studied specieswith ample data.

One alternative to using predicted shifts inspecies’ ranges or changes in vegetation is touse projected changes in climate alone or inconjunction with static elements of the environ-ment to determine where conditions are likelyto be more or less constant. Saxon et al. (2005)used a combination of edaphic conditions andprojected future climates to identify environ-ments that would likely change more and thosethat would likely change less. Reserves couldbe located in areas projected to experience lesschange, or in areas that connected shifting en-vironments. Such an approach relies on pro-jected future climatic conditions, and thus isstill imbued with uncertainty, albeit less uncer-tainty than approaches that involve additionalclimate-envelope or DGVM modeling.

Another alternative that has been proposedis to base reserve selection on the underlyingedaphic conditions and/or current climatic orbioclimatic gradients. Bedrock, soils, topogra-phy, and climatic gradients largely define thenatural distribution of flora, fauna, and ecosys-tems. By protecting diverse combinations ofthese factors, it may be possible to preserve theecological stage on which new players (species)will find themselves in future climates. Onesuch approach that captures current climaticgradients would be to select multiple reserves

for a given species that protect a wide range ofclimatic conditions within that species’ range(Pyke et al. 2005; Pyke and Fischer 2005).

Increasing Connectivity

In the past, species have moved across con-tinents as climates changed and glaciers ad-vanced and retreated (Davis and Shaw 2001).One of the biggest differences between thosehistoric periods and today is that humanshave dramatically altered the Earth’s surface.Agricultural lands, roads, dams and water di-versions, urban areas, and residential develop-ment all act as barriers to movement for somespecies. These barriers will make it difficult formany species to move from areas that becomeunsuitable or to occupy new climatic zones orhabitats that emerge in the future. Using a com-bination of statistical climate-envelope model-ing and mechanistic dispersal models, Iversonet al. (2004) explored the potential of five easternAmerican tree species to colonize newly emerg-ing climatic space over a 100-year period. Noneof the five species was able to colonize morethan 15% of the areas projected to be suitableunder future climates. Such work implies thatthe number of species that are able to move suc-cessfully in response to today’s anthropogenicclimatic changes will be a small fraction of thenumber that were able to move in response tohistoric climate shifts.

The highly fragmented nature of today’slandscapes has led many conservation biolo-gists to promote increasing connectivity amongprotected areas to enhance movement in achanging climate (Shafer 1999; Noss 2001;Hulme 2005; Welch 2005). Most of the researchand discussion on connectivity has focused onwildlife corridors, although some work has ad-dressed corridors for plants (e.g., Williams et al.

2005). Almost all of this work has taken aspecies-by-species approach to corridors. Suchan approach is justified, given that corridors,like habitat, are species-specific concepts. Theability to move through a corridor depends onspecies-specific behavior and habitat affinities.

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Given that many species, with diverse habitatrequirements and dispersal abilities, will needto move in response to climate change, species-based corridor approaches may not be ade-quate or feasible (Hulme 2005).

Two additional approaches to increasingconnectivity have been proposed. First, as men-tioned earlier in this chapter, small stepping-stone reserves can be placed between largerpreserves to facilitate movement (Shafer 1999)(Fig. 1D). This approach may provide connec-tivity for a more general group of species thanspecies-specific corridors, but small reserves willbe limited to a small range of environmentalconditions, and thus may only provide habi-tat for select and potentially small groups ofspecies. Similarly, new reserves, whether theyare small or large, can be placed in close prox-imity to existing reserves to facilitate move-ment (Halpin 1997). The second approach is tomanage the lands or waters between protectedareas in ways that allow the most species tomove through these spaces. Such approacheshave been referred to as softening or man-aging the matrix (Franklin et al. 1992; Noss2001). Some combination of matrix manage-ment, stepping-stone reserves, and corridorswill likely allow the most movement in responseto climate change.

Restoring Habitat and System Dynamics

Clearly, the restoration of ecosystem func-tioning and habitat in degraded areas plays akey role in increasing resilience for systems andspecies. Many have highlighted the need to re-store functioning ecosystems to address climatechange (Hartig et al. 1997; Mulholland et al.

1997; Joyce et al. 2008; Peterson et al. 2008).However, climate-induced changes in hydrol-ogy, disturbance regimes, and species distribu-tions will make restoration goals moving tar-gets, thereby challenging the way restoration istypically done (Harris et al. 2006).

Climate change calls into question two ofthe basic tenants of restoration (Harris et al.

2006). First, most current restoration aims to

return a system to historic or predisturbanceconditions (Swetnam et al. 1999). In some cases,this may still be a viable option. However,for many systems, climate change will make itcostly if not impossible to recreate past ecolog-ical states. Changes in atmospheric CO2 con-centrations will likely alter competitive relation-ships between plant species in multiple ways(Schlesinger et al. 2001). For example, increasedwater-use efficiency due to increased atmo-spheric CO2 concentrations may allow treesto move into more arid environments, shift-ing shrublands to woodlands and woodlandsto closed-canopy forests. Trying to maintaina shrubland in such an area of transition willbe costly and potentially ineffective. Second,much current restoration takes a species-basedapproach, focusing on restoring species com-position. Successfully restoring specific speciesassemblages will require relatively accurate pre-dictions of which sites will be suitable for whichspecies in the future and how those specieswill interact under projected climatic condi-tions. Given the uncertainty inherent in fu-ture climate projections, our limited knowledgeof species-specific responses to climate change,and the inherent uncertainties in most eco-logical forecasting tools, it is unlikely that wewill soon have future predictions that are ac-curate enough to successfully describe specificspecies assemblages at a given site in the distantfuture.

Harris et al. (2006) suggest a shift awayfrom restoring historic conditions and specificspecies assemblages. As an alternative to thesetraditional approaches, they propose restor-ing process instead of structure. By focusingon ecosystem services instead of species com-position, ecosystems can be managed in amore flexible way in which species assemblageschange with changing climates, but ecosys-tem functioning—although the nature of thosefunctions might change—is preserved. Sev-eral suggestions have been made for restor-ing disturbance regimes, river and stream-flow regimes, and wetland hydrology (Hartiget al. 1997; Noss 2001; Harris et al. 2006).

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Concentrating on the abiotic aspects of systemswill help to prepare sites and systems for newconditions and new sets of species.

Although ecological models may not yet beable to provide accurate enough predictions offuture species assemblages to allow managersto concentrate all of their efforts on a few keyspecies, models are currently accurate enoughto inform restoration efforts. Climate-envelopemodels and DGVMs can provide an estimate ofhow the species composition at a site might shiftover time, giving managers an idea of the typesof new species that they might incorporate intorestoration actions and the species for whichcontinued preservation at a site might be futile.Simulation models can also be used to explorethe potential effects of restoration efforts in achanging climate. Battin et al. (2007) integratedthe results of climate models, land-use models,hydrology models, and populations models toinvestigate the potential effects of restorationefforts for Chinook salmon under two differentclimate-change scenarios. Higher stream tem-peratures, higher peak winter flows, and lowerflows during spawning are likely to lead to de-creases in salmon populations. Because changesin flow regimes had the largest effect at higherelevations and restoration efforts were concen-trated at lower elevations, their model indicatedthat the combined effect of climate changeand restoration would shift salmon breedingto lower elevations.

Adaptive Management

Adaptive management is often cited as acritical approach to addressing climate change(Millar et al. 2007; Kareiva et al. 2008; Lawleret al. in press-b). Adaptive management in-volves an iterative process in which managerslearn from experimental management actions(Holling 1978; Walters and Hilborn 1978).Management actions are applied as experi-ments, the system is monitored, and actions arethen potentially changed to address changesin the state of the system. In theory, adap-tive management allows for the management

of highly uncertain systems. Thus, it is poten-tially an ideal approach for dealing with the un-certainties surrounding future climatic changesand future climate impacts (Arvai et al. 2006).Adaptive management can be passive or active(Walters 1986; Walters and Holling 1990). Pas-sive adaptive management generally involvesbuilding a management strategy based on his-toric data and then altering that strategy withnew data as the system is monitored overtime. Active adaptive management involvesconscious experimentation, generally exploringthe outcomes of multiple management strate-gies. Both types of adaptive management willlikely be needed to address climate change.

Applying adaptive management to addressclimate change will be an iterative multistepprocess (Kareiva et al. 2008). First, such a pro-cess will involve assessing the potential impactsof climate change on a system. This wouldnecessarily be a comprehensive assessment inwhich as many of the potential ramifications ofchanges in climate, including changes to distur-bance regimes, hydrology, species composition,food resources, phenology, and interspecific in-teractions are all considered. Second, manage-ment actions will need to be designed to ad-dress these impacts. These actions should beseen as experiments. In some cases, in whichthe scale and the nature of the problem areamenable, it will be possible to conduct multi-ple experiments to explore competing hypothe-sized effects of climate change or to account fordifferent potential shifts in climate. However,for large-scale management problems, a pas-sive adaptive management approach will benecessary. Third, the system will need to bemonitored for both climatic changes and po-tential system responses. Finally, managementstrategies will need to be reevaluated and po-tentially redesigned before the cycle is repeated(Kareiva et al. 2008).

Although adaptive management is a very ap-pealing concept and it is often written intomanagement plans, it has been implementedin relatively few instances (Walters 1997).Two of the better known examples include

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water management in the Florida Everglades(Walters et al. 1992) and the management offlows for the Glenn Canyon Dam (NationalResearch Council 1999). Some of the barriersto successfully implementing adaptive manage-ment include the lack of institutional flexibilityand capacity, the perceived risks of failure, highdegrees of uncertainty, and large spatial andlong temporal scales of management (Gregoryet al. 2006). All of these factors will challengeadaptive management as a tool to address cli-mate change. Nonetheless, it is still likely to beone of the best tools managers and scientistshave to address climate change and to learnabout its effects.

Translocations

Even with increased connectivity betweenprotected areas, some species will need to bemoved to prevent extinction. Species with lim-ited dispersal abilities and small, isolated rangesmay have trouble tracking shifting habitats ormay be left without suitable habitat altogether.For at least some of these species, translocationsmay be the only solution (Bartlein et al. 1997;Honnay et al. 2002). Although recommenda-tions for translocation are not new (Petersand Darling 1985; Orians 1993), conservationbiologists have generally been reluctant totackle the issue of the purposeful movementof species outside of their known native range.Such translocations raise critical ecological andethical questions that will need to be addressedbefore attempts to relocate species are made(Hunter 2007; McLachlan et al. 2007).

Given the impacts that invasive species haveon ecological and economic systems, translo-cations may have costly ramifications even ifwell researched, planned, and executed.McLachlan et al. (2007) discuss two of the basicbarriers to implementing translocations. First,it is difficult to predict which potential candi-dates for translocation will potentially becomeinvasive. Although research on invasive specieshas produced some information about com-mon traits of invasive species, in general, even

with this information, predicting invasion is dif-ficult. Second, determining where to transplantspecies requires an understanding of how en-vironments will change in the future and whatnew areas will provide suitable habitat. As dis-cussed earlier in the chapter, projections of fu-ture climatic conditions and ecological forecastsbased on those projections are still relativelyuncertain. To be useful for assessing potentialsites for translocations, these projections andforecasts will need to incorporate these uncer-tainties. Given these potential barriers to imple-menting translocations, a framework for assess-ing the feasibility of, and risks associated with,a given translocation is essential.

Hoegh Guldberg et al. (2008) recentlyproposed just such a framework (Fig. 2). Theirproposed framework involves several basicquestions and management options. The firstquestion asks what the risk of extinction or pop-ulation decline is likely to be under future pro-jected climates. If the risk is low, assisted mi-gration is not likely to be needed. If the riskis moderate, the authors suggest enhancing re-silience by increasing landscape connectivity,reducing non-climate-related threats, and in-creasing genetic diversity. If the risk is high,one asks whether translocation and establish-ment is technically possible (the second ques-tion in the framework). If not, actions may stillbe taken to help create suitable habitat in newareas in hopes that organisms will get thereon there own. If translocation is possible, oneasks the third question—whether the benefitsof a translocation outweigh the potential eco-logical and socioeconomic costs. If the bene-fits outweigh the costs, translocations can beundertaken.

Specific Recommendationsfor Addressing Climate Change

The strategies discussed in the preceding sec-tions are all basic concepts or general recom-mendations. Here, I provide a few examples ofmore specific actions that have been proposed

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Figure 2. Framework for planning potential species translocations in a changing climate. [This figure wasadapted with permission from Hoegh-Guldberg et al. (2008) and AAAS.]

for addressing climate change in freshwater,marine, and terrestrial systems.

Freshwater Systems

In response to climate change, freshwatersystems are expected to experience changesin temperature, flow, evaporation rates, waterquality, and species composition (Frederick andGleick 1999; Poff et al. 2002). In many mon-tane systems, reduced snowpack and earlierspring melts will result in changes in the tim-ing and intensity of spring and summer streamflows (Barnett et al. 2005; Milly et al. 2005).Wetlands, particularly those that are depen-dant on precipitation, are likely to be someof the most susceptible to climate change ofall aquatic systems (Burkett and Keusler 2000;Winter 2000). Increased evaporation rates and

changes in temperature will result in reduceddissolved oxygen concentrations and changesin species composition.

Rising water temperatures will result in shiftsin species distributions, including the potentialloss of cold-water fish from some lower streamreaches and from other streams all togetherand expansions of the ranges of warm-waterfish (Carpenter et al. 1992; Eaton and Scheller1996). Riparian restoration has been proposedas one method to reduce stream temperaturesand create cool water refugia (Palmer et al.

2008; Scott et al. 2008). Riparian restorationprojects would also help to provide connec-tivity among some terrestrial systems. Protect-ing headwaters and identifying and protectingexisting thermal refugia will also enhance theability of cold-water fish to persist as tempera-tures rise (Hansen et al. 2003).

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A number of management actions have beensuggested for dealing with increases and de-creases in flows (Palmer 2008). Some of theseinclude channel reconfiguration, dam removalor retrofit, floodplain restoration, dam-basedflow management, and bank stabilization. Forexample, creating wetlands and off-channelbasins for water storage during times of extremeflows may prevent excess water from reach-ing reservoirs and reduce downstream flows(Palmer et al. 2008). The removal of sedimentfrom reservoirs may also increase water storagecapacity in the short term (Palmer et al. 2008).Water releases from dams and transporting fishmay be necessary short-term solutions in timesof drought or extreme low flows (Palmer 2008).Finally, reducing water extraction will be a key,although controversial, approach to maintain-ing flows (Hansen et al. 2003).

Marine Systems

Although marine systems are less studiedthan terrestrial systems and the Intergovern-mental Panel on Climate Change (IPCC)has documented fewer significant biologicalchanges in marine systems, many of thosechanges can be linked to climate change(Richardson and Poloczanska 2008). As infreshwater and terrestrial systems, speciesmovements, phenological shifts, and physiolog-ical effects of climate change will have signifi-cant effects in marine systems (Perry et al. 2005;Portner and Knust 2007). Marine species andsystems, however, face an additional challengeas increased CO2 concentrations continue toacidify the oceans (Ruttimann 2006; Guinotteand Fabry 2008).

Increasing ocean temperatures have resultedin the bleaching of corals around the world. Anumber of specific adaptation strategies havebeen proposed to address the loss of corals(Hansen et al. 2003). One such strategy involvesthe reduction of synergistic stressors such ashigh irradiance. Shading and water disruption(with sprinklers) are two methods that are beingexplored to reduce irradiance during periods

of elevated water temperatures. Another ap-proach to protecting coral reefs involves iden-tifying resistant and resilient coral populationsthat are less susceptible to higher temperatures(Hansen et al. 2003; West and Salm 2003).These populations may be able to recolonizebleached reefs, or may be transplanted in at-tempts to restore damaged reefs.

As in other systems, reducing other threatsto species or ecosystems will likely enhance theresilience of marine systems. Reducing fishingpressure and damaging fishing techniques suchas dynamite and cyanide fishing will increasethe resilience of fish stocks and reefs (Hansenet al. 2003). Reducing nutrient pollution willlikely reduce the frequency and extent of harm-ful algal blooms that are a combined result ofincreased nutrients and increased ocean tem-peratures (Mudie et al. 2002). Decreasing load-ing of nutrients and other pollutants will requirechanging land-use practices in coastal water-sheds and in many cases over much larger areas(Hansen et al. 2003).

Terrestrial Systems

A common recommendation for enhancingthe adaptive capacity of terrestrial systems, par-ticularly forested systems, is to broaden thegenetic variability and the species diversity ofmanaged sites (Harris et al. 2006; Millar et al.

2007). Instead of using seed or individuals fromlocal or even regional populations, it may beadvantageous to maximize the genetic diver-sity at a restoration or reintroduction site bytaking genetic material from a broader rangeof locations within a species, range.

Many researchers have called for aggressiveforest-management practices to address climatechange in forested systems. For example, widelyspaced thinning and shelterwood cuts may al-low forest stands to withstand increased insectoutbreaks and fires (Dale et al. 2001; Joyce et al.

2008). Prescribed burning can be used to re-duce fuel loads, and hence the risk of catas-trophic fire (Spittlehouse and Stewart 2003;Scott et al. 2008). Furthermore, aggressive site

Lawler: Climate Change Adaptation Strategies 89

preparation has been proposed to enhance re-generation after disturbances (Spittlehouse andStewart 2003).

Manipulative management strategies havebeen suggested for other systems as well. For ex-ample, moderate grazing has been proposed toincrease the hydroperiod in vernal pools threat-ened by increasing temperatures and decreas-ing precipitation (Pyke and Marty 2005). Theplacement of snow fences has been proposedto increase snow pack in areas where sensi-tive alpine plant communities are threatenedby reduced snowpack (Hansen et al. 2003). Fora wide variety of systems, invasions by nonna-tive species may be minimized through vigi-lance, early detection, and aggressive removal(Hansen et al. 2003; Baron et al. 2008).

New Perspectives

None of the general or specific strate-gies mentioned here is new. For example,even translocations are not without historicanalogs. Reintroductions are merely transloca-tions within the historic range of a species. Fur-thermore, the introduction of species for biolog-ical control should, theoretically, evoke a similarset of precautions that need to be taken whenspecies are moved to address climate change.In fact, most of the general adaptation strate-gies and many of the specific actions describedearlier are the basic accepted strategies for pro-tecting biodiversity in general. How, then, willmanagement need to change in the face of cli-mate change?

Although many of the traditional strategiesfor protecting biodiversity will be critical for ad-dressing climate change, applying these strate-gies will require a new perspective. Thus, mostof the necessary change in management willrevolve around how established strategies areapplied. For example, as discussed earlier inthe chapter, restoration will be a critical toolfor addressing climate change. However, suc-cessful restoration in a changing climate willrequire largely abandoning historic conditions

and managing for dynamic processes and com-munities. Other shifts in perspectives that willbe required to address climate change includebroadening the scale of management, engagingin scenario-based planning and management,and embracing triage as a necessary tool.

Scale

Effectively managing resources in a changingclimate will require taking a broader spatial andtemporal perspective (Franklin et al. 1992; Scottet al. 2002; Welch 2005; U.S. EnvioronmentalProtection Agency 2008). Instead of consider-ing a population, community, or ecosystem inisolation, it will be essential to manage thesewithin a regional or even continental context.For example, it will be necessary to considerthe relative location of a population within thegeographic range of the species and to coordi-nate the management of that population withothers throughout the range. Given changesin climatic conditions, it may be necessary toabandon efforts to manage a population at oneedge of the species’ range and to shift efforts toother populations elsewhere in the range. Be-cause management strategies and practices willneed to cross both land-ownership and politicalborders, they will require both intergovernmen-tal and interagency coordination (Soto 2001;Hannah et al. 2002). In particular, some re-searchers have called for new administrativestructures such as interagency teams or pro-grams with a mandate to address climatechange (Kareiva et al. 2008).

Scenario-Based Planning

The uncertainty inherent in future climate-change projections means that it will often berisky to manage for one anticipated future cli-mate. Current practice often involves manag-ing for a set goal, for example, a population size,a particular forest structure, an allowable sed-iment load, or a specific species composition.One or more strategies are then developed toattain that set goal. In certain climates, a given

90 Annals of the New York Academy of Sciences

goal may be unattainable. Climate change willforce managers and planners to evaluate mul-tiple potential scenarios of change for a givensystem and then to develop alternative manage-ment goals and strategies for those scenarios.

Scenario-based planning has its origins inmilitary theory, and it has been used to exploreplanning strategies in a variety of disciplineswhen future conditions are uncertain (Petersonet al. 2003). The IPCC uses a scenario-basedapproach to exploring the range in potentialfuture climates given different greenhouse-gasemissions scenarios (Nakicenovic et al. 2000).The different scenarios make different assump-tions about human population growth, eco-nomic and social cooperation, advances andacceptance of new technologies, and consump-tion. Applying these scenarios results in dif-ferent projected concentrations of greenhousegasses, which, in turn, result in different degreesof warming and different changes in precipita-tion (IPCC 2007b). Alternative future scenarioshave also been used to evaluate the impacts ofalternative development strategies on biodiver-sity (White et al. 1997; Schumaker et al. 2004).In these studies, land-use scenarios were de-veloped based on preferences for conservationand urban and suburban development. Mod-els were then used to evaluate the potential im-pact of the different scenarios on populationpersistence.

Battin et al. (2007) explored the effects of twodifferent climate-change scenarios and threedifferent restoration scenarios on salmon pop-ulations. The two different climate scenarioswere projected to increase peak flows duringthe salmon incubation period by 7% and 28%,respectively. The six different scenario combi-nations resulted in different changes in popula-tion size, ranging from a 40% decrease to a 19%increase, depending on the scenario. This studyillustrates how different management actionswill have different impacts, depending on theway climate changes in the future. Nonetheless,it also demonstrates the possibility of identifyingmanagement options that yield benefits acrossall scenarios—in other words, “robust” options.

Regardless of which climate scenario was ap-plied by Battin et al. (2007), restoration andprotection of lowland salmon habitats yieldedsignificant benefits. Attempting to identify theserobust management options may prove morefruitful than trying to determine an optimalmanagement strategy.

Scenario planning can be incorporatedinto adaptive management to help managersaddress climate change. Whereas a more tra-ditional approach to active adaptive man-agement might involve simultaneously testingseveral alternative management strategies toattain a set goal, active adaptive managementfor climate change will require testing severaldifferent management strategies designed toattain different goals under different climate-change scenarios. Developing the different sce-narios and goals will require knowledge of therange of plausible future climate-change pro-jections and some estimate of how those dif-ferent climatic changes will affect the systemor species in question. This type of scenario-based approach will require managers to thinkin parallel, in essence, planning for a systemwith several potential future states.

Triage

Given the relative scarcity of funding forconservation and management of naturalresources, prioritizing management needs isalready an integral part of the organization-wide planning of most government agenciesand environmental nongovernmental organi-zations. Climate change will likely stretch thosefunding resources even thinner. With many sys-tems, species, and sites requiring active adap-tive management to address climate change,managers and planners will have to make dif-ficult decisions about where to allocate fundsand efforts. In many cases, we will have tochoose which populations, and perhaps evenspecies, to let go extinct. As the ecological ef-fects of climate change grow in magnitude inresponse to more rapid changes in climate anddisturbance regimes, triage will likely become

Lawler: Climate Change Adaptation Strategies 91

Figure 3. Triage classification schemes for medical emergencies and for managingecosystems and species in a changing climate.

an integral part of higher-level planning andmanagement.

Triage—from the French verb trier, to sort—is a method of prioritization developed for treat-ing patients in emergency situations. Priorityfor treatment is based on the severity of theinjuries and the potential for survival. Thereare generally four basic triage classifications:deceased or expectant, critical, severe, and mi-nor. Patients in each of these categories receivea different treatment (Fig. 3). Applying triageto conservation and management decisions isnot a popular topic, and as such, has receivedrelatively little attention. There are both ethi-cal and ecological reasons that triage is a bitterpill for both conservationists and conservationbiologists to swallow (Kareiva and Levin 2003).The loss of a population or a species may havemassive implications for the functioning of anecosystem in some cases or very little effect ona system in others.

A simple triage system for addressing climatechange would provide a classification based onseverity that paralleled the medical classifica-tion (Fig. 3). Some systems, species, or sites willlikely undergo such substantial changes thatthey will be beyond managing with the avail-

able resources. Others will need to be managedimmediately and constantly, but such manage-ment will be feasible. Still others will need to bemanaged but might be able to wait a few yearsif they are closely monitored. Finally, the restof the species and systems will either requireno management or will require some manage-ment in the future, but won’t be lost if actionisn’t taken soon. These systems and species canbe monitored if resources are available.

Medical triage approaches are often mod-ified to address specific situations. For exam-ple, in a widespread emergency, if some of theinjured include members of the medical pro-fession, those doctors or nurses may receive ahigher priority, even if they have relatively mi-nor injuries, due to their value to the emergencyresponse effort. A triage system for addressingclimate change could likewise take the relativeimportance of species or ecosystems into ac-count (Fig. 4). Rare species or systems, or highlyvalued species might be deemed of higher pri-ority even if the severity of climate impactwas projected to be relatively low. Species withhigh interaction strengths, particularly ecosys-tem engineers and keystone species, might, forexample, receive higher priorities than other

92 Annals of the New York Academy of Sciences

Figure 4. Triage classification for managing natural resources in a changing climate thataccounts for both the severity of the climate threat and the value of the resource. The classifi-cation presented here is just one of a many potential manifestations of such a classification.

species. For example, beaver have the abilityto alter hydrological systems in ways that maybuffer streams from the effects of reduced snow-pack and earlier spring runoff events. Thus,even if beaver are not likely to be highly affectedby climate change, it may be wise to ensure theresilience of beaver populations in some systemsfor the benefit of the system as a whole. Systemsand species that provide critical ecosystem ser-vices (again, beaver are a good example forservices such as flood control and trout) mightalso be given higher priorities. There are clearlyother ways to evaluate species and ecosystemsthat go beyond ecological impact. For exam-ple, the loss of a species may have little impactecologically, but a large impact socially or eco-nomically (Ruckelshaus et al. 2003). Here againthe concept of ecosystem services may be able

to play a key role in prioritization and triage inthe face of climate change.

Future Research Directions

The vast majority of recommendations forfuture research involve better understandinghow species and systems will respond to climatechange (Peters and Darling 1985; Kappelle et al.

1999; Noss 2001; Schlesinger et al. 2001; Hulme2005; Root and Schneider 2006). Althoughsuch an understanding is clearly important, di-recting the bulk of our research efforts to thisgoal will likely produce far too little, much toolate. Because responses to climate change willbe species and system specific, we will likelydiscover few new generalities that will allow us

Lawler: Climate Change Adaptation Strategies 93

to develop widely applicable adaptation strate-gies. Arguably, many of these generalities arealready known (e.g., species will move in re-sponse to climate change, changes in phenol-ogy will decouple ecological systems). Insteadof solely attempting to document system- andspecies-specific responses to climate change, tosuccessfully address the challenge of how to re-spond to these changes, research efforts willneed to have a much more applied focus.

Because understanding how each speciesand system will respond to climate change isnot feasible, perhaps the most critical task forresearchers is to determine which, if any, ofthe general concepts and basic prescriptions foradaptation will work and where and how theywill work best. With respect to conservationplanning, we should be asking whether aligningreserves along latitudinal or elevational gradi-ents, connecting reserves with stepping stones,and expanding the bioclimatic footprint of re-serves will provide more protection than merelyincreasing the number or size of reserves. Withrespect to removing other threats and envi-ronmental stresses, we will need to determinewhich existing threats and stresses will havethe strongest synergistic interactions with ris-ing temperatures and changing precipitationregimes.

Many of the general adaptation strategiesfocus on managing systems and landscapes toeither lessen the impacts of climate change orto allow species to move in response to climatechange. Fewer strategies are aimed at increas-ing the potential for evolution in the face ofclimate change. For many long-lived species,evolution will not be an option. Others, how-ever, may be able to evolve in response towarmer temperatures, wetter or drier condi-tions, or changing habitats. Which populationsand which species will have more evolutionarypotential? How can we promote evolutionarypotential through restoration, management,and conservation planning?

Given the critical role that adaptive man-agement is likely to play in addressing climatechange, one of the most important research

needs involves gaining a better understand-ing of how to implement adaptive manage-ment. What is the best way to explore multipleclimate-change scenarios in an adaptive man-agement setting? What will need to be moni-tored? How often will monitoring need to bedone? There has long been a call for increas-ing the amount of adaptive management that isactually implemented. Implementing adaptivemanagement in a changing climate will bothallow us to learn more about the ecological ef-fects of climate change and to provide flexiblemanagement approaches.

Assigning priorities will require an under-standing of which systems and species will bemost vulnerable to climate change. Assessmentsof climate-change vulnerability and potentialimpacts can provide that knowledge (Desankerand Justice 2001; Kareiva et al. 2008). Althoughthere are many potential approaches to de-veloping a vulnerability assessment for climatechange, any assessment would need to includeat least two basic elements: (1) a measure of in-herent sensitivity, and (2) projections of how andwhere climate will change. Additionally, a vul-nerability assessment might include estimatesof the adaptive capacity of a system, species,management agency, or society in general(McClanahan et al. 2008). Measures of inher-ent sensitivity can be taken from the literature,although, for many species and systems there isstill little knowledge about their sensitivities tochanges in temperature or precipitation. Thevulnerability of individual species could be de-termined by factors such as physiology, specifichabitat requirements, interspecific dependen-cies, dispersal ability, and population dynam-ics and location. An assessment of ecosystemvulnerability would include factors such as hy-drologic or fire sensitivities, component–speciessensitivities, and vulnerability to sea-levelrise.

Determining where the largest climaticchanges are likely to occur will require fine-scale predictions of future climate. There areseveral methods that take local climatic condi-tions and topographic variation into account to

94 Annals of the New York Academy of Sciences

derive finer resolution climate data from coarseresolution general circulation model (GCM)projections (Wilby et al. 1998). Because of thevariability across GCM projections, it will benecessary to assess potential future climaticchanges based on a range of different climate-change projections. In addition to assessing cli-matic change, it will often be necessary to as-sess where potential climate-driven changes indisturbance regimes, the structure of vegeta-tion, and species composition will be the great-est. Hydrological models can be used to gen-erate predicted changes in hydrology (de Witand Stankiewicz 2006), and fire models can beused to project changes in fire frequency, size,and severity (McKenzie et al. 2004). DGVMscan be used to generate predicted shifts inbasic vegetation types corresponding to gen-eral habitat types (Bachelet et al. 2001; Crameret al. 2001) and climate-envelope models can beused to assess how particular, sensitive specieswill likely respond to climate change or wherechanges in flora or fauna might be the great-est (Thuiller et al. 2005; Lawler et al. in press-a). Ideally, these species distribution modelsshould take species dispersal abilities and land-scape patterns into account to determine howspecies will move and where greenways andhabitat corridors might be placed to enhancemovement.

Finally, understanding how climate changewill affect ecosystem services will be criticalfor setting priorities, conducting triage, and de-signing restoration projects. As discussed ear-lier in this chapter, assigning limited resourcesto a large number of potential managementprojects in an efficient way will require prioritiz-ing those projects based on both the severity ofpotential climate impacts and the values of thesystems, species, or populations. The conceptof ecosystem services is one such valuation ap-proach. Moving from species-based restorationto a concentration on restoring ecosystem func-tioning and ecosystem processes will also beaided by the concept of ecosystem services, andwill require an understanding of how ecosystemservices will be affected by climate change.

Conclusions

Managers already have many of the toolsnecessary to address climate change. The vastmajority of these tools are those recommendedfor protecting biodiversity and managing nat-ural resources in general. What is needed inthe face of climate change is a new perspec-tive. Each of these tools—enhancing connec-tivity, restoration, translocations—will need tobe applied in light of the fact that disturbanceregimes and ecosystems will change and speciesand pathogens will move. This new perspec-tive will require expanding the spatial andtemporal scale of management and planning.It will require restoring ecosystem function-ing and managing for ecosystem services in-stead of species composition. It will includeactive adaptive management using scenario-based approaches. And, it will involve priori-tization, and as climatic impacts become moreacute, triage to determine which species andwhich ecosystem processes we will save.

Acknowledgments

I thank Molly Cross, Peter Kareiva, and LaraHansen for stimulating discussions that helpedshape the paper. Molly Cross, Evan Girvetz,Peter Kareiva, and Bill Schlesinger providedhelpful suggestions for improving earlier drafts.

Conflicts of Interest

The author declares no conflicts of interest.

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