forest wildlife management and conservation森林野生动物管理与保护

THE YEAR IN ECOLOGY AND CONSERVATION BIOLOGY,2009Forest Wildlife Managementand ConservationDavid B.LindenmayerFenner School of Environment and Society,The Australian National University,Canberra,AustraliaForests are critical for the world’s biodiversity,the regulation of the Earth’s climate,and the provision of goods and services for humans.This review focuses on four broad top-ics:(1)key processes threatening forest biodiversity;(2)broad strategies for mitigating threatening processes;(3)climate change and forest biodiversity;and,(4)plantations and biodiversity.How key issues within these broad topics are addressed will have pro-found effects on forest biodiversity and the Earth’s climate.A significant global problem for biodiversity conservation is the conversion of natural forests to other land uses,both in developing and developed nations;ways must be urgently identified to halt forest con-version.When forests are logged for timber or pulpwood and then regenerated,impacts on biodiversity are harder to quantify than when forests are converted to other land uses.Hence,the effectiveness of efforts to mitigate such impacts(where they occur)is frequently not well known.Climate change may result in substantial changes to forest ecosystems,and its effects may interact in additive or cumulative ways with other hu-man disturbances in forests,although work on such combinations of impacts is in its infancy.The establishment of plantations of trees is frequently proposed to sequester large amounts of carbon and/or produce biofuels to mitigate the climate-change effects. However,there is potential for perverse outcomes,such as biodiversity loss where plan-tation establishment is narrowly focused and other environmental values are ignored. Key words:forests;biodiversity;reserves;off-reserve management;climate change; plantations;adaptive management;monitoringIntroductionNative or natural forests are among the most species-rich environments on earth,making them critical reservoirs for many groups of biota ranging from vertebrates to microbes(Torsvik et al.1990;Gill1995;Crozier et al.1999).Na-tive forests are also key stores of forest carbon (IPCC2007;Mackey et al.2008)and as a result have a major role to play in the mitigation of climate-change impacts.It is not the aim of this chapter to comprehen-sively review the broad range of topics within forest management and forest biodiversity con-Address for correspondence:David B.Lindenmayer,WK Hancock Building West(43),The Australian National University,Canberra,ACT, 0200,Australia.david.lindenmayer@.au servation.This would be an almost impossible task given the massive proliferation of journals and other kinds of literature examining such subjects.Nor does this review attempt to repeat the considerable content of key texts on for-est biodiversity conservation(e.g.,DeGraff and Miller1996;Hunter1999;Lindenmayer and Franklin2002).Rather,this review examines a subset of existing and emerging issues associ-ated with the management and conservation of the world’s forests and forest biodiversity. Four broad(and strongly interrelated)top-ics are covered:(1)key processes threatening forest biodiversity.(2)broad strategies for miti-gating threatening processes.(3)climate change and the conservation of forest biodiversity.and (4)plantations,biodiversity conservation,and the risks of“bio-perversity.”A brief overview of each topic is accompanied by a discussion ofThe Year in Ecology and Conservation Biology,2009:Ann.N.Y.Acad.Sci.1162:284–310(2009). doi:10.1111/j.1749-6632.2009.04148.x C 2009New York Academy of Sciences.284Lindenmayer:Forest Wildlife Management&Conservation285complexities,challenges,and unresolved issues. Thefinal part of this review touches on some key challenges for the conservation and man-agement of forest ecosystems and identifies some of the knowledge gaps that need to be closed.Processes Threatening Forestsand Forest Biodiversity Several key factors threaten,or have the po-tential to threaten,forest biodiversity.Four of these are(1)forest conversion to other forms of land cover,(2)logging,(3)salvage logging, and(4)altered natural-disturbance regimes. They are briefly discussed in the remainder of this section and are a prelude to the follow-ing one on mitigating their impacts.An entire section of this review is dedicated to a brief dis-cussion of afifth threatening process—climate change.Forest ConversionForest conversion is the clearing and replace-ment of native forest with some other kind of land cover,such as for grazing for domestic live-stock and agriculture,plantation establishment, and urban settlement.Land conversion is one of the greatest threats to native forests and forest biodiversity on all of the Earth’s vegetation continents and in both developed and developing nations.For-est conversion removes habitat for many forest-dependent species.This is a major issue because habitat loss is the primary driver of species loss worldwide(reviewed by Groombridge and Jenkins2002;Fahrig2003;Lindenmayer and Fischer2006;Schipper et al.2008). Calculating annual rates of forest conversion is problematic because of inadequate satellite coverage and arguments over definitions of for-est clearing.The Food and Agraculture Organ-isation of the United Nations(FAO2007)esti-mates that0.3%of the world’s area of forests or 13million ha is cleared annually.Annualfigures for tropical humid forests are∼120,000km2 with most of the world’s14–18million km2now cleared,primarily in the last50years.For trop-ical dry forests,annual rates of conversion have been estimated to be40,000km2(Chivian and Bernstein2008).Such estimates of forest con-version do not include the area of forest subject to traditional forms of high-intensity logging such as clearfelling,which removes temporar-ily forest cover but aims to regenerate stands following harvesting(see later in the chapter). They also do not include areas of forest sub-ject to illegal logging where stands may not be clearfelled,but large structurally andfloris-tically important trees are removed(Koenig 2008).In many jurisdictions,the primary reason for forest conversion is to create areas for domestic livestock grazing and agriculture(UNEP1999; Foley et al.2005;Millennium Ecosystem Assess-ment2005;UNEP2007).Other factors can re-sult in forest conversion.For example,clearing of native forests to establish plantations is a ma-jor form of land conversion worldwide(Jackson et al.2005;FAO2007)and has been a driver of biodiversity loss in such places as Australia (Tyndale-Biscoe and Smith1969),Asia(Ara-trakorn et al.2006),and South America(Grez et al.2006;Barlow et al.2007).For example,in Malaysia alone,several million hectares of na-tive forest have been cleared to establish planta-tions.Relatively large areas of private forest in the United States are at risk of conversion from expanding urban development,putting an ar-ray of species at risk,including many threatened taxa(Robles et al.2008).Complexity and IssuesA major challenge is the development of better social,economic,ecological,and other strategies to slow(and eventually halt)forest conversion(Koh and Wilcove2007),includ-ing in those areas such as central Africa where extensive areas of intact rain forest are unpro-tected in reserves,although not currently sig-nificantly threatened(Koenig2008).286Annals of the New York Academy of SciencesFrom an ecological perspective,there is a re-markable paucity of empiricalfield studies in the conservation biology literature that have directly quantified relationships between for-est conversion and species loss(Fazey et al. 2005a).It may be that many conservation bi-ologists perceive that quantifying relationships between habitat loss and species loss are too trivial to warrant detailed examination(Fazey et al.2005a).Y et important questions remain about the relative influence on species richness and species persistence of the total amount of habitat versus the spatial pattern of that habi-tat(Fahrig2003).This,in turn,has significant implications for the way forests are managed, particularly the number and location of harvest units across landscapes(Franklin and Forman 1987).Forest Logging Substantial areas of native forests are logged globally each year.For example,as estimated 5000km2of forest is cut annually in Asian Russia,primarily by clearcutting.Over four bil-lion cubic metres of timber and pulpwood are produced annually(FAO2001).Many forms of forestry result in the maintenance of vegeta-tion cover,but forest suitability for many species and assemblages can be significantly reduced (Franklin et al.1981;Lindenmayer and Franklin 2002).There is an enormous and highly complex literature on the effects of logging on ecosys-tem processes and biodiversity.Logging modi-fies forest environments in diverse ways over a range of spatial and temporal scales.Some of the many effects of logging include:•Altered forest composition.Harvesting and re-generation aimed at maximizing timber production typically leads to long-term changes in forest composition(Kellas and Hateley1991;Mueck et al.1996;Ough 2001).Both tree and nontree compo-nents can be altered by harvesting,thin-ning,or culling(Halpern and Spies1995).Some species(especially commercial tree species and aggressive understory shrubs and herbs)are often favored while other species decline.Successional trajectories after logging often differ markedly from those that occur after natural disturbances (McRae et al.2001).In other cases,log-ging can inadvertently result in the intro-duction of invasive plant species(Linden-mayer and McCarthy2001;Brown and Gurevitch2004).•Altered abundance and spatial distribution of structural attributes.Logging can reduce the structural diversity of stands,such as that associated with live trees,snags,large logs, and thickets of understory vegetation(Lin-der and¨Ostlund1998),as well as altering the spatial distribution of these attributes (Hilmo et al.2005).Stand structure is of-ten simplified,sometimes drastically,such as when clearcutting is repeatedly utilized (Lindenmayer and Franklin1997).Animal populations that depend on particular for-est attributes,such as cavity trees and de-caying wood,are often negatively affected by commercial logging(deMaynadier and Hunter1995;Lindenmayer et al.2002b; Karraker and Welsh2006).•Altered spatial patterns of vegetation types and stand age classes.Logging of managed forests usually occurs with higher frequency and greater regularity than natural distur-bances(McCarthy and Burgman1995), at least in forest types that are subject to episodic,stand-replacing disturbances.As a consequence of forest regulation and fre-quent harvesting,natural stand age-class distributions are truncated to support uni-form areas of younger stands(Seymour and Hunter1999).Those uniform areas also tend to be of a smaller size and have more discrete edges than those created by natural disturbances(McRae et al.2001). Changes in the spatial pattern of forest age classes may affect populations of some el-ements of the biota,such as large forest owls(Milledge et al.1991;Lamberson et al.Lindenmayer:Forest Wildlife Management&Conservation2871994)and some wide-ranging forest mam-mals(Noss and Cooperrider1994;Linden-mayer et al.1999).•Landscape dissection by transportation infrastruc-ture.Transportation networks constructed for moving logs can provide access to previ-ously remote regions,encouraging the ex-pansion of human populations and associ-ated agricultural practices(Harcourt1992;Putz et al.2000),as well as increasing pres-sure on species that are hunted(Redford 1992;Bull et al.2001).The World Commis-sion on Forests and Sustainable Develop-ment(World Commission on Forests and Sustainable Development1999)estimates that between400and2000ha of forest are lost for each kilometer of new road constructed in Brazilian Amazonia.Forest roads and railways also may have the following effects.•Redirect large quantities of runoff andsilt into aquatic ecosystems(Naiman andBilby1998).•Increase mortality of animal speciesthrough collisions with vehicles(Trombulak and Frissell2000;Formanet al.2002).•Facilitate movement of native predatorsand feral predators(e.g.,the red fox[Vulpes vulpes]and feral cat[Felis cattus]in Australia)(May and Norton1996;May2001)and weeds or invasive plantspecies(Wace1977).•Alter habitat connectivity(sensu Linden-mayer and Fischer2006)for particularorganisms.As an example,culverts un-der roads change patterns and speedsof waterflow in aquatic ecosystems andcan provide significant barriers to themovement of some organisms such asfish(Boub´e e et al.1999;Walker1999).Logging and associated forest-management practices can directly or indirectly affect key ecosystem processes and forest biota in a range of other ways.For example,logging can com-pact the soil(Rab1998),and fertilizers ap-plied to promote tree growth or herbicides used to control undesired plants can accumulate in the soil or in hydrological systems(White et al. 2006).Prescribedfire or hazard-reduction(“slash”) burning is a management activity often asso-ciated with logging and is used to encourage postharvesting stand regeneration and/or re-duce the likelihood and intensity of wildfire (Whelan1995)(but see Moritz et al.2004).It can influence hydrological regimes,rates of soil ero-sion,and patterns of nutrient cycling(Van Lear et al.1985;Carter and Foster2004;Morley et al. 2004).Prescribed or hazard-reduction burn-ing also can alter(1)vegetation composition (Haskins and Gehring2004;Syphard et al. 2006),(2)the spatial pattern of vegetation types, (3)the structure of stands,and(4)the com-position of animal communities(James and M’Closky2003;Schurbon and Fauth2003; Noss et al.2006).The spatial and temporal patterns of logging can have many influences on forest ecosystems. These influences may be small,for example, where logging involves cutting relatively small areas,very long rotations,or the retention of high levels of biological legacies(sensu Franklin et al.2000).Conversely,short rotations,and high levels of utilization,such as occur with clearcutting and even-aged stand management, produce numerous homogenous cut blocks in a landscape.Such outcomes may have significant negative impacts at multiple spatial scales,in-cluding landscape-level cumulative effects(e.g., Franklin and Forman1987).Complexity and IssuesThe impact of native forest logging on forest biodiversity has been a controversial topic for many decades(Yaffee1994;Dargarvel1995; Lindenmayer and Franklin2003;Ajani2007). Studies quantifying logging impacts are an im-portant part of developing effective strategies to mitigate such effects.However,robust stud-ies of logging impacts are far from straightfor-ward.Many investigations to date have been288Annals of the New York Academy of Sciencesproblematic for a range of reasons.Just three ofthese are:•A number of studies have contrasted logged and unlogged areas,but have con-founded logging impacts with the effectsof site productivity on biodiversity.Thisis because low productivity areas that re-main unlogged(but support inherently lowabundances of some taxa)have been com-pared with higher productivity logged sites(Lindenmayer and Franklin2002).•Detecting long-term impacts of logging on biodiversity can be extremely difficult be-cause forest trees can be long-lived organ-isms and the stand development processcan span hundreds of years.Many investi-gations have substituted space for time inan attempt to overcome this,but this canfail to account for the important influenceof site history on biodiversity(Gustavssonet al.2007),leading to erroneous conclu-sions(Pickett1989).•Some of the most significant impacts of logging on biodiversity are cumulative over space,over time,or both.That is,the im-pact of a single cutblock in a forest land-scape might be limited,but substantial effects may arise when many areas are harvested over the course of a rotation (Franklin and Forman1987).For exam-ple,the loss of structural complexity within stands can accumulate over many cutover sites and result in highly homogenised landscapes.Some of these problems can be overcomethrough the careful design and implementationof true experiments and natural experiments,although these can be limited in spatial scalewith associated constraints for inference aboutparticular groups of biota such as wide-rangingspecies(Lindenmayer and Franklin2002).Ex-periments also often will not provide much use-ful information about cumulative logging ef-fects on forest biodiversity.Such kinds of effectsare extremely difficult to quantify(Cocklin et al.1992;Paine et al.1998)and may require the integration of a range of kinds of data such as those from observational studies,landscape analyses,monitoring programs,and simulation modeling.It is clear that it is not possible to conduct the “perfect”study to quantify logging effects on forest biodiversity.However,researchers need to be more aware of the limitations of their work and account for them in interpreting their results,particularly in the context of improved management for forest biodiversity.Salvage LoggingSalvage logging is defined by the Society of American Foresters(Helms1998)as:“the re-moval of dead trees or trees damaged or dying because of injurious agents...to recover eco-nomic value that would otherwise be lost.”Its potential effects on forest biodiversity are best considered separately from those of traditional (green-tree)logging considered in previous sec-tions because(1)it may have additional and/or different effects,(2)salvage logged timber and pulpwood is an increasing component of the wood harvested from forests in many parts of the world,and,(3)salvage logging is likely to become more common in the future,as climate change may result in large-scale natural distur-bances becoming more frequent(Cary2002), widespread(Breshears et al.2005;Flannigan et al.2005),intense(Emanuel2005),or all of these(Goldenberg et al.2001;Westerling et al. 2006).Salvage logging is widespread around the world and takes place after such disturbances as:•wildfires(Hutto2006);•insect attacks(Government of British Columbia2007a);•hurricanes,cyclones,and windstorms (Foster and Orwig2006);•floods(Gregory1997)and debrisflows (Beschta1979);•volcanic eruptions(Dale et al.2005). Lindenmayer and Noss(2006)noted that salvage logging can differ from traditionalLindenmayer:Forest Wildlife Management&Conservation289(green-tree)logging in four ways:(1)the con-ditions preceding logging,(2)the conditions under which logging takes place,(3)what is logged,and(4)the prescriptions used to guide logging operations.As in the case of green-tree logging,the impacts of salvage logging on forest biodi-versity will vary in response to factors such as:•type,intensity,frequency,and spatial pat-tern of logging;•the levels and types of biological legacies that are retained;•specific nature of the ecosystem,ecological processes,and biota involved. However,three additional factors will influ-ence the magnitude of salvage logging effects:•the type and severity of the preceding natu-ral disturbance(e.g.,windstorm vs.wildfire vs.insect attack);•combined impacts of the type and intensity of a preceding disturbance and a specific intensity and pattern of logging(Odion et al.2004;Thompson et al.2007);•postdisturbance weather conditions(e.g., their influence on mass movements of de-bris(Helvey et al.1985).Salvage logging can have a range of nega-tive impacts on forest ecosystems.It may re-duce or eliminate biological legacies,modify rare postdisturbance habitats,influence popu-lations,alter community composition,impair natural vegetation recovery,facilitate the colo-nization of invasive species,alter soil properties and nutrient levels,increase erosion,modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity (Bergeron et al.1993).Complexity and IssuesAs in the case of traditional(green-tree)log-ging discussed in the preceding section,ro-bust studies to document the effects of salvage logging are critically important for designing strategies to mitigate its impacts on forest bio-diversity.However,few such studies have been completed to date(reviewed by McIver and Starr2001;Lindenmayer et al.2008a),and there are significant deficiencies in several of those that have been conducted.There is an ur-gent need for more and better designed salvage logging investigations because salvaged wood is a large component of the cut from native forests (Nappi et al.2004),and this is likely to further in-crease with climate change–driven increases in large-scale/high-severity natural disturbances (Lindenmayer et al.2008a).Altered Natural-DisturbanceRegimesLogging operations have the potential to significantly alter natural-disturbance regimes with corresponding impacts on some ele-ments of biota.This is important because natural-disturbance regimes are increasingly recognized by ecologists as critically impor-tant ecosystem processes that help create habi-tats and resources for biodiversity(Connell 1978;Sousa1984;Parr and Andersen2006). Many aspects of the composition and struc-ture in forests at the tree,stand,ecosystem, and landscape scales are shaped by natural dis-turbances(Parminter1998;Cary et al.2003; Frelich2005).In addition,many species have strong associations with natural-disturbance regimes—some positive and some negative (Bergeron et al.1993;Bunnell1995;Spies et al. 2006).Logging-induced altered natural-distur-bance regimes can result in the development of such problems as(1)the direct loss of species associated with particular frequencies,intensi-ties,or timing of disturbances(Woinarski1999), (2)failure to recruit key elements of stand struc-tural complexity such as large-diameter cavity trees(Gibbons et al.2008)with correspond-ing impacts on taxa dependent on such struc-tures(Fischer and McClelland1983;Rose et al.290Annals of the New York Academy of Sciences2001),and(3)increased risks of subsequent high-severity disturbances(e.g.,wildfires and pest outbreaks),with corresponding negative impacts on plants and animals(Thompson et al. 2007).A key aspect of landscape-level sustainable forest management and biodiversity conserva-tion is the management of natural disturbances such asfire(R¨u lcker et al.1994;Keith et al. 2002)and grazing(Vera2000).In the partic-ular case of the management offire regimes, this may involve both the suppression of un-wanted(wild)fires and ignition of prescribed fires(Gill1999).Issues associated with the im-pacts of disturbances byfire and its effects on biota are complex.This is because in some landscapes,such as those in Sweden,problems like a lack of regeneration of particular plant species have been created by the absence of fire(Zackrisson1977),whereas in others such as ponderosa pine(Pinus ponderosa)stands in the southwestern United States,fire suppres-sion together with livestock grazing mean that wildfires are too intense(Moore et al.2004; Noss et al.2006).The objectives offire man-agement will vary depending on the proximity of people and property and the relative im-portance of values like timber resources,con-servation,and water production(Keith et al. 2002).The most appropriatefire regime also will depend on the characteristics of the system (R¨u lcker et al.1994).Differences between veg-etation communities and individual elements of the biota in their response tofire mean that there are no simple management recipes(Whe-lan1995).Natural-disturbance regimes may be varied between and within landscapes,to create a range of conditions.Therefore,if un-suitable habitats are created in one area for a given species,there will be other places it can survive.Complexity and IssuesMany natural disturbance–related issues in forests have yet to be resolved.Some paradigms such as the intermediate-disturbance hypothe-sis have equivocal support as do others like“py-rodiversity begets biodiversity”(Parr and An-dersen2006).Complexities arise because,while single intensive and/or large-scale disturbances can have profound impacts(Turner et al.2003), in many cases it is the disturbance regime(sensu Gill1975)or the sequence of disturbances over time and the timing,intensity,and spatial pat-tern of each perturbation in the regime,that has the greatest impacts.It is hard to quan-tify the most appropriate disturbance regime(s) for a given species,forest type,or forest land-scape because of the spatial and temporal vari-ability in attributes,such as intensity,frequency and timing(Gill1975),and relationships with other issues,such as the ensembles of patch types and conditions that underpin the devel-opment of landscape mosaics(sensu Bennett et al.2006).A further issue is that although the use of natural-disturbance regimes to guide human-induced disturbances has considerable merit (Hunter2007),it also has limitations.First,the concept is both difficult to test and actually remains largely untested in most forest ecosys-tems.Second,some complex forest ecosystem processes are extremely difficult to emulate (James and Norton2002).Third,natural distur-bances sometimes induce nonlinear or thresh-old changes in ecological processes,species in-teractions,and population sizes in which there is a sudden switch from one state to a markedly different one(Walker et al.2004).Fourth,the needs of particular taxa and the conservation requirements for particular areas may not be met.Many landscapes have changed as a result of human disturbances such as vegetation clear-ance,and“natural”disturbance regimes may no longer be appropriate or achievable.Human disturbance will never be a perfect analog for natural disturbance,nor are human and nat-ural disturbances independent.Rather,there may be magnified or cumulative effects result-ing from both of them occurring in the same broad area.Salvage logging after natural distur-bance is a prominent example(Lindenmayer et al.2008a).Lindenmayer:Forest Wildlife Management&Conservation291Broad Strategies for Mitigating the Impacts of Processes ThreateningForest BiodiversityTwo broad kinds of strategies are fundamen-tal for the conservation of forest biodiversity: reserve-based conservation and off-reserve con-servation.A third—the implementation of ap-propriate natural-disturbance regimes(see ear-lier in this chapter)—is relevant both to reserves and areas outside them.The importance of off-reserve conservation is sometimes ignored by some conservationists,perhaps because it is felt that it might undermine the case for increased reservation.Nevertheless,off-reserve areas,in-cluding those that have had a history of human use(including past logging),are important for forest biodiversity conservation.Forest ReservesLarge ecological reserves are an essential part of all comprehensive biodiversity conser-vation plans(Gaston et al.2008).They are critically important for at least three promi-nent reasons(after Lindenmayer et al.2006)as follow.•They support some of the best examples of ecosystems,landscapes,stands,habitat, and biota and provide opportunities for natural evolutionary processes.•Many speciesfind optimum conditions only within large ecological reserves,which become strongholds for these species.These include taxa intolerant of human intrusion,and for which it is imperative to retain some areas that are largely exempt from human activity.•Large ecological reserves provide“control areas”against which the impacts of hu-man activities in managed forests can be compared.Complexity and IssuesMany issues are associated with the design and management of forest reserves.There is an urgent need to improve the comprehensive-ness,adequacy,and representativeness of forest reserves around the world(Gaston et al.2008). The adequacy of the surrogate schemes used to drive reserve design algorithms and other approaches such as gap analysis also needs ad-ditional careful appraisal(Pressey et al.2007). Some authors have suggested alternative and/or additional approaches to improve the efficiency and effectiveness of reserve design and conservation actions.For example,the number of species conserved may be signif-icantly enhanced by targeting protection ef-forts at biodiversity hot spots where there are exceptionally high levels of species richness and endemism(Mittermeier et al.1998;Myers et al.2000).While this concept has consider-able merit,areas that are hot spots for partic-ular groups may not be species-rich for oth-ers(Ceballos and Ehrlich2006).Mittermeier et al.(2003)suggested that the protection of existing areas of wilderness could make a sig-nificant contribution to conservation because these areas are inhabited by few humans.How-ever,they recognized that these areas are often not species-rich(Mittermeier et al.2003).In ad-dition,some threats,such as those created by invasive species,may occur in areas where hu-man population densities are low(Mackey et al. 1999.In summary,several ways of prioritizing bio-diversity conservation have been developed,al-though they are primarily underpinned by a framework of irreplaceability and vulnerabil-ity(Brooks et al.2006).The relative merits of these approaches remains poorly understood, not only for forest reservation but for biodiver-sity conservation per se.Because forest ecosystems,and hence stand conditions,are dynamic,particular kinds of forest often need special attention,either im-plicitly within planning tools for reserve design or explicitly outside them.For example,the ecological values of early-successional forests recovering from large-scale,high-severity nat-ural disturbances have only recently been rec-ognized(Franklin and Agee2003;Turner et al.。