Prospects for sustainability of biodiversity based on conservation biology …planet.uwc.ac.za/nisl/Gwen's Files/Conservation Biology... · · 2006-09-14Prospects for sustainability

Ž .Landscape and Urban Planning 40 1998 47–71

Prospects for sustainability of biodiversity based on conservationbiology and US Forest Service approaches to ecosystem

management

David W. Crumpacker )

UniÕersity of Colorado, Department of EnÕironmental, Population and Organismic Biology, Campus Box 334, Boulder, CO 80302, USA

Abstract

Ecosystem management involves long-term management of whole ecosystems, across political boundaries as necessary,to sustain ecosystem integrity. The conservation biology view of ecosystem management tends to be biocentric, placingprimary emphasis on sustaining the integrity of natural ecosystem processes and native species. The US Forest Servicefavors an anthropocentric approach in which an array of public preferences will determine the extent to which utilitarianŽ . Ž .commodities, recreation, etc. and natural biodiversity values will be emphasized in defining and sustaining ecosystemintegrity. Conservation biologists have suggested creation of a national network of regional reserve systems, with core areas,buffer zones, and landscape linkages, to help maintain biodiversity, while the US Forest Service is promoting the use oftimber management and other forest practices to mimic historic biodiversity patterns across the landscape. These ideas arenot mutually exclusive, could potentially be complementary, and would be long-term, very challenging efforts. Politicalsupport for implementation of these ideas is uncertain. Legislative proposals to transfer large amounts of multiple-use, publiclands to state andror private ownership, if enacted, are likely to render these approaches ineffective. Compelling scientificevidence from conservation biology argues that failure to apply some sort of ecosystem management to the remainingnatural and seminatural parts of the US landscape will result in continued loss of natural biodiversity, eventually leading to a‘tragedy of the biodiversity commons’. Failure to support the present federal land management goal of providing publiclydesired resources while sustaining ecosystem integrity can be expected to have negative effects on ecosystem services,regardless of the emphasis placed on naturalness. Broad legislative guidelines favoring maintenance of natural biodiversity,but allowing a much greater contribution of local communities to land management planning, offers the potential forsustaining both ecosystem integrity and localrregional economies. This approach is risky with respect to sustaining naturalecosystem integrity but can, perhaps, be guided by knowledge obtained from adaptive management. Prospects for successwould be strengthened by financial incentives to nongovernmental entities for protection of natural biodiversity, concern forprivate property rights, and by different kinds of stakeholders who share a common ethical andror cultural concern for thenatural environment of their communities. q 1998 Elsevier Science B.V.

Keywords: Ecosystem management; Biodiversity; US Forest Service; Conservation biology; Landscape ecology; Nature reserve systems;Sustainability; Ecosystem integrity

) Corresponding author. Tel.: q1-303-492-8726, 8981; fax: q1-303-492-8699; e-mail: [email protected]

0169-2046r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved.Ž .PII S0169-2046 97 00098-4

( )D.W. CrumpackerrLandscape and Urban Planning 40 1998 47–7148

1. Introduction

Ecosystem management has been defined andviewed in various ways. Most traditional ecosystemscientists would probably consider ecosystem man-agement to be biogeochemical management, with afocus on how ecosystems absorb and process solarenergy, how they move or ‘cycle’ materials such ascarbon and nitrogen, and how they provide a life-support system for organisms which, in turn, affectecosystem processes. While this type of ecosystemmanagement is potentially compatible with speciespreservation, one can imagine major ecosystemsmanaged for energy acquisition that are relatively

Ž .depauperate in native species Seastedt, 1994 . Putanother way, efforts to enhance biodiversity are likelyto maintain high-quality biotic support systems butthe reverse may not be true. Tree plantations, ‘im-proved’ rangelands, and reservoirs might provide ahealthy mix of ecosystems that contain little naturalbiodiversity.

An alternative definition of ecosystem manage-ment has developed in response to what is believedto be either a pending or worsening biodiversity

Žcrisis see Smith et al., 1993 for a discussion of.current and future extinction rates . This definition

stems from a conservation biology view that hastraditionally emphasized the biotic components of anecosystem, the latter being typically defined as abiotic community of species interacting with oneanother and with their abiotic or ‘physical’ environ-ment. This sort of ecosystem management aspires tomaintenance of the natural integrity of ecosystems,including native species as well as natural biogeo-chemical processes. A healthy ecosystem in this caseis one that sustains native species in naturally occur-ring, self-regulating, and naturally evolving commu-nities until they become extinct from nonhuman-re-lated causes. An important human value judgment isincluded here, viz., that future environments should

Žsustain i.e., maintain or even increase, when possi-.ble natural biodiversity as well as human and eco-

nomic health. This view of ecosystem management,which is common among conservation biologists,includes the concept of restoring all or parts ofecosystems in order to assist with the maintenance of

Ž .natural biodiversity Sinclair et al., 1995 .US federal agencies have generated much recent

interest in ecosystem management by promoting itsŽuse in management of natural resources Morrissey

.et al., 1994 . Although the federal agency approachto ecosystem management grew out of concerns for

Žloss of biodiversity from protected areas Agee and.Johnson, 1988 , it is now visualized as a proactive

method for ensuring a healthy, sustainable environ-Žment and economy Interagency Ecosystem Manage-

.ment Task Force, 1995 . The US Forest Service hasbeen the most prominent promoter and developer ofthis federal initiative. It views ecosystem manage-ment as a means of changing from a traditionalemphasis on multiple uses such as timber, grazing,water, recreation, and wildlife to a primary goal ofsustaining ecosystem integrity. Multiple uses wouldcontinue to be of much importance but would usu-ally be provided within ecological limits imposed bythe need to maintain ecosystem integrity.

There is general consensus among all of the aboveparties that ecosystem management involves the needfor long-term management of whole ecosystems andso across political boundaries as necessary, in orderto sustain ecosystem integrity. There is less agree-ment on the priority that should be given to manage-ment of human activities within ecosystems. Further-more, the terms ecosystem integrity and ecosystemhealth have different implications for the mainte-nance of natural ecosystems and native species, de-pending on the perspective of the manager. The

Ž .present report will 1 provide a brief account of thedevelopment of conservation biology and Forest Ser-vice views and plans concerning ecosystem manage-

Ž .ment; 2 discuss the implications of these view-Ž .points for maintenance of biodiversity; 3 mention

some of the political resistance to implementation ofecosystem management, and its potential conse-

Ž .quences; and 4 consider ways in which publicguidelines and local community action might interactto sustain reasonable, and possibly essential, amountsof natural biodiversity on the US landscape.

2. Concepts and definitions

2.1. A preÕailing Õiew of ecosystem managementamong conserÕation biologists

Ž .Grumbine 1994 surveyed papers published onecosystem management in peer-reviewed journals

( )D.W. CrumpackerrLandscape and Urban Planning 40 1998 47–71 49

through June, 1993, as well as various books, envi-ronmental publications, and agency documents. Tendominant themes were identified, leading to the fol-lowing ‘working’ definition: ‘‘Ecosystem manage-ment integrates scientific knowledge of ecologicalrelationships within a complex sociopolitical andvalues framework toward the general goal of protect-ing native ecosystem integrity over the long term’’.He then listed five specific goals related to sustain-

Ž .ing ecological integrity: 1 maintain viable popula-Ž .tions of all native species in situ; 2 represent,

within protected areas, all native ecosystem typesŽ .across their natural range of variation; 3 maintainŽevolutionary and ecological processes i.e., distur-

bance regimes, hydrological processes, nutrient cy-. Ž .cles, etc. ; 4 manage over periods of time long

enough to maintain the evolutionary potential ofŽ .species and ecosystems; and 5 accommodate hu-

man use and occupancy within these constraints.The first four of the above goals are apparently

derived from, or at least related to, those of ClarkŽ . Ž .and Zaunbrecher 1987 , Grumbine 1992 , and Noss

Ž . Ž .1991a,b, 1992 . Noss and Cooperrider 1994 de-scribed them in more detail and considered them tobe ‘‘comprehensive and idealistic so that conserva-tion programs have a vision toward which to striveover centuries’’. They are value statements aimed atalleviation of the biodiversity crisis. These goals areclosely related to certain ethical principles, most ofwhich are probably shared by the majority of conser-vation biologists, i.e., diÕersity of organisms is good,untimely extinction of populations and species is

Žbad, ecological complexity interactions amongspecies and between species and their physical envi-

. Žronment is good, eÕolution in natural environ-.ments is good, and biodiÕersity has intrinsic Õalue

Ž . Žregardless of its value to human society Soule,´.1985; Primack, 1993 .

Ž .Wilcove and Blair 1995 have argued that thefirst four goals listed by Grumbine appear to be inorder of their importance. This is not because aparticular species is more important than, e.g., ahydrological process or a nutrient cycle, but becausespecies protection offers a more easily understood,practical way to maintain the other values.

Ž .Grumbine’s fifth goal also a value acknowledges

Ž .the ‘vital if problematic ’ role of humans in naturalecosystems but is clearly made subsidiary to themaintenance of native biodiversity. Noss and Coop-

Ž .errider 1994 have argued in this regard that biologyis a better ‘bottom line’ for making land use deci-sions than socioeconomic criteria because humancultural systems can adjust much more rapidly tonew conditions than can other species and ecosys-tems. The biological basis for this argument has been

Ž .presented more explicitly by Pickett et al. 1992 .They noted that the evolution and dispersal of speciesover geologic time has kept pace with extensiveenvironmental changes that have occurred on earth.However, today’s global biota can not be expected toadjust to the extensive anthropogenic environmentalchanges that are occurring on a scale of decades oreven a few years. There are physiological limits towhat species and ecosystems can tolerate, and previ-ous long-term, evolutionary processes may not haveproduced enough naturally occurring species in theright locations to meet the new stresses in a compen-satory fashion. Conservation biologists must, there-fore, help to devise management systems that willprotect native species and the processes that maintainthem, while simultaneously educating the publicabout the need to limit large-scale changes in natu-rally occurring ecosystems. Examples of the latterare extensive conversions of natural forests to otherland uses, global warming, and widespread environ-mental toxification.

Grumbine’s definition of ecosystem managementand the associated goals have been referred to as an

Ž .‘academic consensus’ by Alpert 1995 and as a‘shift from anthropocentric values towards biocentric

Ž .values’ by Stanley 1995 . They are described in thisreport as ‘a prevailing view’ among conservationbiologists because of their emphasis on nativespecies, native ecosystem types, and native ecosys-tem integrity. This is consistent with the emphasis onimportance of native species diversity in naturallyoccurring, changing, and evolving ecosystems thatunderlies the notion of conservation biology as a

Žcrisis discipline Soule, 1985; Fiedler and Jain, 1992;´Primack, 1993; Meffe et al., 1994; Caughley and

.Gunn, 1996; Hunter, 1996 . The degree to which abiocentric concern is adhered to by conservation


biologists will obviously vary among individuals andcannot be ascertained precisely without a survey ofseveral thousand practising professionals.

2.2. The forest serÕice Õiew of ecosystem manage-ment

The Forest Service concept of ecosystem manage-ment grew out of the ‘New Perspectives’ initiativelaunched in 1990 by Chief F. Dale Robertson. NewPerspectives proposed ‘‘a different way of thinkingabout managing the national forests and nationalgrasslands, emphasizing ecological principles, to sus-

Žtain their many values and uses’’ USDA Forest.Service, 1991 . The four guiding principles of New

Perspectives were to sustain healthy ecosystems, in-volve people as partners, strengthen the scientificbasis for management, and use collaborative prob-lem-solving. This led to a policy change in the waymultiple uses would be managed, i.e., ecosystemmanagement, which was described by then Deputy

Ž .Chief James C. Overbay as follows Overbay, 1992 :

The Forest Service has managed ecosystems since itsinception. But, beyond the protection of about 20%of the National Forest System in wilderness, researchnatural areas, and wild rivers, that management oftenfocused more on selected parts of ecosystems thanon the wholes or on the processes that keep ecosys-tems healthy, diverse, and productive. Our knowl-edge has evolved. Our thinking has evolved. It istime to embrace the concept of managing ecosystemsto sustain both their diversity and productivity and tochart a course for making this concept the foundationfor sound multiple-use, sustained-yield management.

Overbay then pointed out that goals are not obvi-ous from definitions and that ecosystem managementgoals will come from laws that govern the Forest

ŽService, the RPA Forest and Rangeland Renewable.Resources Planning Act program, forest plans, and

project decision documents. A little later he statedthat desired resource values, uses, products, andservices will not be treated as by-products to bederived from the preservation of intrinsic values ornatural conditions of ecosystems. Rather, the ForestService will consider that ‘‘ecosystem managementmeans to produce desired resource values, uses,products, or services in ways that also sustain the

diversity and productivity of ecosystems’’. Importantdifferences between this original Forest Service ver-sion of ecosystem management and that described byGrumbine are the lack of detail about what is meantby ‘diversity’, the reference to multiple-use and sus-tained-yield concepts that will not be subordinate tonatural conditions of ecosystems, and the lack ofspecific references to native ecosystems and nativespecies. Sustained yield, as used by Overbay, refersto achievement and maintenance in perpetuity of ahigh level of annual or regular output of the variousrenewable resources of the national forests without

Žimpairment of the productivity of the land see Jensen.and Everett, 1994 . Renewable resources include

multiple uses such as timber, grazing, water, wildlife,recreation, and wilderness.

The Forest Service has traditionally consideredmost multiple uses as secondary to the dominant useon a particular site, e.g., timber on productive forestland, big game on winter range, winter sports on skiareas, or wilderness on areas so designated. Thepractical effect of this has been to emphasize com-modity production at the expense of uses more closelyrelated to biodiversity. Ecosystem managementseemed in 1992 to represent a change in ForestService philosophy from optimization of yield levelsamong competing resources to sustaining resourceyields that are compatible with the overall ecologicalcondition of the land. As stated by Kessler et al.Ž .1992 in the context of New Perspectives, ‘‘the newparadigm must not diminish the importance of prod-ucts and services, but instead treat them within abroader ecological and social context’’.

It is now clear that the Forest Service is beginningto implement, through ecosystem management, anew land management ethic. In his first report to theUS Congress as Chief of the Forest Service, Jack

Ž .Ward Thomas, said Thomas, 1994 :

I believe in a land ethic that is based on an accep-tance of constraints on human treatment of land inthe short term to ensure long-term preservation ofthe integrity, stability, and beauty of the biotic com-munity. Human activity that is consistent with thisethic is properly within the realm of resource man-agement options. That which would violate this ethicshould be resisted for all but the most compellingreasons. Having said that, I also recognize that peo-


ple are inseparable from ecosystems and their variedneeds must be accommodated if we are to reachconsensus about how our forests are to be managed.

Recent Forest Service documents provide addi-tional indications of what the agency means byecosystem management. Volume II of the ForestService’s Eastside Forest Ecosystem Health Assess-ment states that the primary objective of ecosystemmanagement is ‘‘to sustain the integrity of ecosys-

Ž .tems i.e., their function, composition, and structurefor future generations while providing immediategoods and services to an increasingly diverse public’’Ž .Jensen and Everett, 1994 . The Forest SerÕice Ethicsand Course to the Future document defines ecosys-tem management as ‘‘the integration of ecological,economic, and social factors in order to maintain andenhance the quality of the environment to best meet

Žcurrent and future needs’’ USDA Forest Service,.1994a .

The Forest Service’s publication entitled A Na-tional Framework for Ecosystem ManagementŽ .USDA Forest Service, 1994b provides a descrip-tion of what the Forest Service means, and intends tomaintain, with respect to biodiversity. It states thatthe Forest Service will ‘‘care for the national forestsand grasslands in ways that sustain populations of allnative plants and animals; provide habitat for healthypopulations of game animals and fish for recreation,subsistence, and commercial use; and protect threat-ened, endangered, and sensitive species’’. Sustain-ability is defined as the maintenance of desiredecological conditions or flows of benefits over time.

Although the National Framework document doesrefer to sustaining native species of plants and ani-mals, the differences mentioned earlier between con-servation biology and Forest Service views ofecosystem management still appear to hold. Theformer is largely biocentric, i.e., places primary em-phasis on native species and the integrity of naturalecosystems, whereas the latter attempts at best tobalance biocentric and anthropocentric concerns.However, the Forest Service’s use of phrases such as

Ž‘‘to best meet current and future needs’’ USDA.Forest Service, 1994a and its lack of a clear legisla-

tive mandate for implementation of ecosystem man-Ž .agement Keiter, 1994a,b certainly leaves the door

open for less biocentric emphasis in the future.

Uncertainty in future determination of the role ofhuman activities within the framework of ecosystemmanagement is illustrated further in a discussion

Ž .sponsored by The Keystone Center 1993 . A large,diverse group of federal, state, and local agencypersonnel, representatives from environmental andcommodity-based organizations, and others tended toagree that ecosystem management should include

Ž .ecological biodiversity, ecological processes , so-cial, and economic objectives but disagreed abouttheir relative importance.

2.3. Concepts of integrity, health, natural and natiÕeas they apply to ecosystems, species and ecosystemmanagement

Some definitions of integrity are closely tied toŽ .the concept of naturalness. Karr and Dudley 1981

defined biological integrity as ‘‘the capability ofsupporting and maintaining a balanced, integrated,adaptive community of organisms having a speciescomposition, diversity, and functional organizationcomparable to that of natural habitat of the region’’.

Ž .Angermeier and Karr 1994 stated that ‘‘biologicalintegrity refers to a system’s wholeness, includingpresence of all appropriate elements and occurrenceof all processes at appropriate rates’’, and that bio-logical integrity is generally defined as ‘‘a system’sability to generate and maintain adaptive biotic ele-ments through natural evolutionary processes’’. Theyconsidered a biota with high integrity to reflectnatural biogeographic, as well as evolutionary, pro-cesses, and that the loss of biological integrity in-cludes loss of natural diversity components such asspecies and communities, in addition to breakdownof the processes needed to generate future naturaldiversity.

Angermeier and Karr’s concept of the interrelat-edness of integrity and naturalness is based on the

Ž . Ž .arguments of Ehrlich and Mooney 1983 that 1Ž .exotic non-native species rarely perform ecosystem

services like energy flow and mineral cycling aseffectively as the native species for which they were

Ž .substituted, and that 2 exotic species, which areoften broadly adapted, weedy generalists, may alsoundergo rapid range expansion, with a concomitantloss of native species, thereby lowering the potential


for future adaptive evolutionary change. As Ehrlichand Mooney also noted, simple loss of a native‘controller’ species such as an important herbivorecan have a dramatic effect on the diversity of anatural plant community. Alternatively, human mod-ification of a community to favor a predominatelynative species monoculture, such as a loblolly pineplantation in the southeastern United States, may notcause important losses in ecosystem services, at least

Žover the short term but it may require relativelylarge expenditures of energy and nutrient subsidies

.to keep the system productive . It is possible that aŽ .general loss of species due to 1 substituting a few

Ž .generalist-type exotics for many native species or 2encouraging native species monocultures may havelittle effect on basic ecosystem processes, as long as

Žno keystone species have been lost Schulze and.Mooney, 1993; Rundel, 1995 . Even so, the lowering

of future evolutionary capability remains a poten-tially serious, longer-term problem.

Other definitions of integrity are not so closelyrelated to the concept of naturalness. For example,

Ž .Cairns 1977 defined biological integrity as ‘‘themaintenance of the community structure and func-tion characteristic of a particular locale or deemed

Ž .satisfactory to society.’’ Regier 1993 argues moreexplicitly that: ‘‘The notion of ecosystem integrity isrooted in certain ecological concepts combined withcertain sets of human values . . . A living systemexhibits integrity, if, when subjected to disturbance,it sustains an organizing, self-correcting ability torecover toward an end-state that is normal and goodfor that system. End-states other than the pristine ornaturally whole may be taken to be normal andgood.’’ Part of Regier’s definition of integrity is verysimilar to the concept of resilience as defined by

Ž .Holling 1973 , viz., the ability of an ecosystem toabsorb shocks and to maintain its integrity even ifthe shocks are so great that the system shifts to anew mode.

It is clear from the above discussion that theecosystem management goal of the Forest Service toemphasize ecosystem integrity, accompanied by pro-duction of timber, livestock, forage, recreational op-portunities, and other multiple-use benefits withinthis constraint, uses a concept of integrity similar tothat of Cairns and Regier. That is, the managedecosystems may have varying degrees of naturalness,

based on public preference. Alternatively, the con-servation biology goal is more biocentric. It aims tomaintain natural ecosystem integrity.

Ecosystem health appears to be a less usefulconcept than integrity for purposes of this reportbecause it has been defined and applied in even more

Ž .disparate ways. Kay 1993 considers ecosystemhealth to be a component of ecosystem integrity; i.e.,

Ž .ecosystem integrity includes 1 ecosystem healthŽthe ability to maintain an optimal operating point

. Ž .under normal environmental conditions , 2 the abil-Žity to cope with stress i.e., changes in environmental

. Ž .conditions , and 3 the ability to continue evolvingŽand developing i.e., to continue the process of self-

.organization on a continuing basis . On the otherŽ .hand, Rapport 1989 considers ecosystem integrity

to be a component of ecosystem health and that ‘‘theprimary requirements for a healthy ecosystem arethose of system integrity and sustainability’’. Ecosys-tem integrity, in turn, ‘‘depends on a small numberof critical functions and structures, including main-taining efficiency in energy transfer and nutrientcycling, and maintaining a diverse species assem-blage in which the longer-lived and larger life-formsare dominant in the mature phase of ecosystemdevelopment’’. Rapport also considers that anecosystem does nor need to be pristine in order to behealthy. A final example of the inconsistency associ-ated with use of the term ‘health’ involves theWestern Forest Health Initiative of the Forest Ser-

Ž .vice USDA Forest Service, 1994c , which definesforest health as ‘‘a condition where biotic and abioticinfluences do not threaten resource management ob-jectives now or in the future’’. Examples of poorforest health that are cited include large wildfires andpest outbreaks that are considered to be indicative ofpreviously undesirable types of management.

The concepts of ‘natural’ and ‘native’ are alsoimportant because of their relationship to differencesbetween conservation biology and Forest Serviceviews of how to accomplish ecosystem management;i.e., whether or not to place major a priori emphasis

Ž .on managing for natural or native ecosystem in-tegrity. As used by conservation biologists, ‘natural’generally refers to a condition or situation that islargely unaffected by humans. This is the meaningthat is most applicable to the present report. Whatpeople perceive as natural is not always obvious.


Human perceptions of naturalness are affected bycultural biases, and the concept of naturalness varies

Ž .in its closeness to reality Hoerr, 1993 . A remnantof annual grassland in coastal California may bedesired as a nature reserve, even though it wasdominated by native perennial grasses several hun-dred years ago. Similarly, a relatively large ham-mock in northern Florida, dominated by native hard-wood tree species and highly valued by a stateconservation agency, may have been largely nativepines several hundred years ago, prior to the modernperiod of active fire suppression.

Naturalness can be used in the context of aborigi-nal, as well as modern human environments. Thus,the suspected ‘Pleistocene overkill’ of large verte-brates that followed the arrival of humans in the

ŽNew World could be considered ‘unnatural’ Ander-.son, 1991 . In Great Britain and Europe, where there

is no condition prior to a major-land use change thatis generally accepted as a description of naturalness,uncultivated lands containing native species, thathave not been subjected to chemical treatments suchas fertilization, may be considered natural or semi-

Ž .natural Margules and Usher, 1981 . A naturalecosystem might be considered one in which the sizeof the human population is limited by its environ-

Ž .ment no import of food, building materials, etc.Žand products of the ecosystem are used locally no

.export of biological material . An approximation tothis might be the conditions in Australia at the time

Ž .of European settlement Margules and Usher, 1981 .It is easy from the practical standpoint to identify

relatively natural and unnatural ecosystems such asEverglades National Park and New York City. Pre-Columbian humans quite likely caused significantchanges in the Greater Yellowstone Ecosystem, butthere is no mistaking the roads, villages, mines,lumbering, and ranches produced by post-Columbian

Ž .humans over the last 200 years Patten, 1991 . An-Ž .derson 1991 has proposed three indices to describe

the amount of naturalness in an ecosystem, as fol-Ž .lows: 1 the degree to which the system would

Ž .change if humans were removed, 2 the amount ofcultural energy required to maintain the functioning

Ž .of the system as it currently exists, and 3 thecomplement of native species currently in an areacompared with the suite of species in the area priorto settlement. Indices 2 and 3 can be quantified. If a

presettlement inventory is not available, the propor-tion of native species in the current system can beused as alternate.

While the term ‘native’ is sometimes used inter-changeably with natural, it is most commonly usedto describe a species that has not been introduced

Žinto an area from somewhere else by humans Noss.and Cooperrider, 1994 . An exotic species is one that

has come to an area as a result of deliberate oraccidental introduction by humans. This could havebeen through direct transport by humans or as aresult of indirect human activities such as habitatalteration. In all of these cases, some sort of humanactivity has permitted the invading species to over-come a natural barrier to dispersal. Exotic speciesthat have become adapted to their new environmentover time are sometimes referred to as ‘naturalized’.

Under natural conditions, species gradually dis-perse and colonize new areas, thereby causing long-term changes in the biota of a region. Human aug-mentation of this process has greatly increased therate of these natural invasions since the Pleistocene,and has caused well-documented destabilizing influ-

Žences on some of the invaded ecosystems Westman,.1990 . All exotic species do not have equally disrup-

tive effects on their recipient ecosystems and somemay even be highly valued by segments of societyŽ .Westman, 1990 . The major concern of conserva-tion biologists is that well-adapted, native communi-ties of species are usually associated with highecosystem integrity, whereas exotic species maylower ecosystem integrity by interfering with naturalecosystem services and also by driving some nativespecies to local extinction. If the latter are endemics,global and local biodiversity will be lowered.

Aside from the contribution of native species toecosystem integrity and to many commodities thathumans value for commercial and recreational pur-poses, natural ecosystems with predominately nativespecies have great aesthetic and spiritual importanceto many people. This is notwithstanding the fact thatthe ‘natural’ condition may be partly a result ofhuman activities several generations earlier. For thesereasons, conservation agencies and organizations of-ten have goals to protect ecosystems with a desired‘historic’ condition or to restore them to such acondition. A complementary goal is to protect orrestore the natural processes, including the natural


disturbance regimes, that produced the historic con-Ž .dition Ecological Society of America, 1995 .

3. Plans for implementation of ecosystem manage-ment

3.1. An approach suggested by conserÕation biolo-gists

Ž .Noss and Cooperrider 1994 have outlined anational strategy for maintaining natural biodiversityin perpetuity. It involves meeting the following goals:Ž .1 represent, in a system of protected areas, allnative ecosystem types and seral stages across their

Ž .natural range of variation; 2 maintain viable popu-lations of all native species in natural patterns of

Ž .abundance and distribution; 3 maintain ecologicaland evolutionary processes, such as disturbanceregimes, hydrologic processes, nutrient cycles, and

Ž .biotic interactions; and 4 manage landscapes andcommunities to be responsive to short-term andlong-term environmental change, and to maintain theevolutionary potential of the biota.

The above goals are very similar to, but moreexplicit than, the first four goals listed by GrumbineŽ .1994 for sustaining ecological integrity, in relation

Žto his definition of ecosystem management see Sec-.tion 2.1 . The Noss and Cooperrider goals are, there-

fore, referred to in the present paper as a ‘conserva-tion biology’ approach for implementing ecosystemmanagement. The phrase ‘in natural patterns ofabundance and distribution’ in Noss and Cooper-rider’s goal 2 implies maintenance or restoration of arelatively natural historic condition in important seg-ments of the landscape. This condition might be onethought to typify the US landscape just prior to themajor land use changes that began with Europeansettlement, although that is not explicitly stated. Goal2 is potentially rather different from the Forest Ser-vice’s goal to ‘sustain populations of all native plantsand animals’ on the national forests and grasslandsŽ .USDA Forest Service, 1994b . The Forest Servicegoal might conceivably be met by maintaining justenough reasonably viable populations of threatened,endangered, and special-interest species to sustainthem over a reasonably long period of time, but in anoverall regional landscape that has considerable un-

naturalness. On the other hand, there would seem tobe no way that the Forest Service could avoid main-taining large amounts of relatively natural habitat insome regions, if it is to meet a goal of sustainingviable populations of large vertebrates such as the

Ž .grizzly bear Ursus arctos horribilis and gray wolfŽ .Canis lupus .

The strategy outlined by Noss and Cooperrider isbased on the concept of ‘regional reserve networks’,which is derived primarily from earlier suggestions

Ž . Ž .by Noss 1983, 1992 , Harris 1984 , and Noss andŽ .Harris 1986 . ‘Regional’ refers to a large landscape

differing from other such types in factors such asclimate, soils, physiography, and species assem-blages; e.g., a bioregion or ecoregion. The NorthCascades, Great Basin, Southern Appalachians, andFlorida would be US examples. A ‘network’ wouldconsist of core reserves, surrounded by buffer zones,and linked by connectors.

A core reserve is an area that would be main-tained in its natural state and within which naturaldisturbance events would be allowed to proceedspontaneously or be mimicked by active manage-ment. Existing protected areas such as national parks,wilderness areas, national wildlife refuges, BLM ar-eas of critical environmental concern, and NatureConservancy reserves might qualify as core reserves.

A buffer zone would surround a core area andpermit a wider range of human uses than the core butstill be managed with native biodiversity as a preem-inent concern. Although a buffer zone would be amultiple-use area, it might differ from a typicalmultiple-use area in a national forest, if the latter didnot have maintenance of native biodiversity as aprimary concern. Ideally, a buffer zone would en-large the effective size of its core reserve, at least forsome species, as well as provide external protectionfor the core. It might also serve as a substitute corearea, if disturbance should render the core habitattemporarily unsuitable. A major intent of the bufferswould be to reduce regional activities harmful tobiodiversity, such as certain types of logging, min-ing, livestock grazing, and off-road vehicle use, innational forest and BLM lands surrounding corereserves. The core reserve–buffer zone idea is verysimilar to the concept of conservation networks pro-

Ž .posed by Salwasser et al. 1987 . Noss and Cooper-rider believe that large changes in national leadership


and agency organization would be required to create,e.g., a national forest buffer zone around a nationalpark core reserve.

Connectivity of core–buffer complexes would beachieved, for at least some species, by corridors ofadequate width, designed with respect to factors suchas movement behavior of species, distance betweenthe complexes, and nature of intervening habitat.Connectivity for species that tend to disperse ran-domly might depend on having a suitable, overalllandscape matrix rather than on a linear type ofcorridor. Connectivity or ‘landscape linkage’ couldserve multiple purposes such as permanent habitat;temporary habitat for movement related to homerange, dispersal out of parental home range, andseasonal migration; and habitat for long-range shiftof species in response to climate change.

Noss and Cooperrider noted that, while mostspecies and processes would probably persist in wellmanaged buffer zones, a conservative approachwould be to represent each regional ecosystem typeat least once in a core reserve and to create a securenetwork of reserves for large carnivores and otherspecies particularly sensitive to human activities. Thelevel of detail at which ecosystems might be classi-fied for the purpose of determining representationwould depend on the extent and complexity of theregion under consideration. One example of a usefulclassification might be The Nature Conservancy’sseries level vegetation types for the western United

Ž .States Bourgeron and Engelking, 1992 . Ideally, thistype of classification would also represent the fullarray of physical habitats and environmental gradi-

Žents that underlie the biodiversity of a region see.Hunter et al., 1988; Noss, 1992 .

Area requirements for maintaining large androrfar-ranging carnivorous species might necessitateseveral interconnected regions such as the entiresoutheastern United States for the Florida pantherand the Northern Rocky Mountains for the grizzlybear. In order to accommodate natural disturbancepatterns that would maintain adequate seral stages ofmajor regional ecosystem types, some core reservesmight have to be many times larger than the averagedisturbance patch of, say, a fire or pest outbreak.

Based on a review of several admittedly verycrude estimates of the total amount of natural habitatneeded to meet the conservation goals of the reserve

network strategy, Noss and Cooperrider suggestedmost regions of the United States would require that25% to 75% of their total land area be in core

Žreserves and inner more highly regulated for conser-.vation buffer zones. Extensive amounts of public

and private lands would need to be involved. Thesepercentages also assume that the core–buffer com-plexes would be well connected both within and,when necessary, between regions. The proposed arearequirements are an order of magnitude greater thanthe amount of land currently protected in most of theregions. Many of the cores and buffers would notneed to be ‘locked up’ because a variety of humanuses could be accommodated, as long as they werecompatible with conservation objectives. Neverthe-less, accomplishment of this strategy would requiremany years of cooperative action among agencies,landowners, citizens and scientists.

A continental-scale effort for developing a collec-tion of regional reserve networks in North Americahas been initiated. It is called The Wildlands ProjectŽ .Noss, 1992 . It involves local groups of people ineach of several regions who are utilizing conserva-tion biology principles to devise regional reservenetwork proposals. The latter will be used to educategovernment agencies, environmental organizations,the general public, and others about the importanceof biodiversity and requirements for protecting it.

3.2. Approaches suggested by forest serÕice person-nel and collaborators

It is important to consider how the Forest Servicemight translate its new ethic of ecosystem manage-ment into land management prescriptions and howthis might affect biodiversity. One aspect of thetechnical part of this question has been summarizedpreliminarily in a report produced by the ForestService’s Eastside Forest Ecosystem Health Assess-

Ž .ment Team Jensen and Bourgeron, 1994 . This re-port is largely concerned with multiple-use lands, asopposed to those national forest lands set aside forwilderness, research natural areas, and other types ofspecial protection. The authors contributing to thisdocument believe ecosystem management can beimplemented with current scientific knowledge andland management experience but that it will have tobe continually assessed and revised, as new experi-


ence and knowledge accumulate. This is to be ac-complished by considering each of the many at-tempts to implement ecosystem management as anexperiment with pre-quantified objectives. Such ob-jectives can then be evaluated as each experimentproceeds. They can also be modified, if necessary,based on what happens, as well as on new informa-tion related to changes in scientific theories andhuman values. This process is called adaptive

Žecosystem management Holling, 1978; Walters and.Holling, 1990; Everett et al., 1994 .

3.2.1. Management of disturbance patterns and Õege-tation

The Forest Service intends to put special empha-sis on regional, landscape-level analyses across vege-

Žtation types ponderosa pine forest, spruce-fir forest,.sagebrush steppe, etc. which, in turn, will be consid-

ered at several spatial and temporal scales. Vegeta-tion types are especially useful representations ofecosystems because of their importance to har-vestable timber and wildlife habitat suitability, andbecause vegetation can be manipulated through com-mercial harvests and other practices to mimic impor-

Žtant natural disturbance regimes Baskerville, 1985;.Swanson and Franklin, 1992 . The major goal will

be to recreate the historic range of variability thatoccurred on the landscape before its extensive modi-fication by European settlers. This approach assumes‘‘that native species have adapted to and, in part,evolved with the natural disturbance events of the

Ž .Holocene past 10,000 years environment. Accord-ingly, the potential for survival of native species isreduced if their environment is pushed outside the

Žrange of its natural variability’’ Swanson et al.,.1994 . Closely tied to this assumption is the addi-

tional assumption that the historic vegetation patternin terms of different types and developmental or

Ž‘seral’ stages shrub seedling, young forest, old.growth, etc. across the landscape can be approxi-

mated by management practices of varying type,intensity, and duration. To reemphasize, if this canbe accomplished, it is assumed that most nativebiodiversity can be maintained—and perhaps in some

Žcases increased—at all levels from landscapes char-.acteristic groupings of ecosystems through ecosys-

Žtems to species and individual populations which.maintain genetic variability within species . Adaptive

ecosystem management will be used to test thesebasic assumptions.

There are important practical problems with theidea of maintaining historic variability patterns ofvegetation by mimicking historic disturbance pat-

Žterns of fire, wind, flood, pests, etc. Swanson et al.,. Ž .1994 . Examples include 1 the difficulty of deter-

Ž .mining past disturbance patterns, 2 the extent towhich present or future environments may be forcedoutside of their historic range by other factors suchas climate, exotic species, and human structuresŽ . Ž .roads, dams, mines, mountain resorts, etc. , and 3whether or not society will permit the type of man-agement that is needed, e.g., restricting the harvest ofold growth forests on public lands in areas where oldgrowth was historically common, but is now rare on

Ž .private lands Wilcove, 1994 or encouraging oldgrowth harvest in areas that were historically domi-

Žnated by fire and younger seral stages Schwartz,.1994; Rauber, 1995 . One example of potential com-

promises would be to use prescribed fire to maintaincertain species populations at individual sites, andtimber harvests to replace natural fire as an impor-tant determiner of landscape vegetation patternsŽ .Swanson et al., 1994 .

Swanson et al. believe that the above suggestionsfor management of disturbance and vegetation areconsistent with productive use of the Pacific North-west landscape where they are based, including tim-ber harvest and fishing. They do point out thatnear-term costs might be increased and that ‘‘Thesocially acceptable balance between ecological andcommodity objectives will be determined by thepublic’’. Thus, it is possible, perhaps probable, thathistoric variability patterns of biodiversity cannot bewell simulated because of political roadblocks, un-less there are fundamental changes in the way thatenvironmental policies are developed and imple-

Ž .mented e.g., see Yaffee, 1994; Roush, 1995 .

3.2.2. Need for additional emphasis on populationsof endangered, threatened, and special-interestspecies, and on protected areas

Complete dependence by the Forest Service onhistoric vegetation patterns to maintain all levels ofbiodiversity would place too much emphasis on the

Ž .‘coarse-filter’ approach Hann et al., 1994 . Thelatter assumes that maintenance of landscape and


ecosystem diversity would simultaneously maintainŽmost of the component species and population i.e.,

.within species diversity. The coarse-filter methodwill not, however, suffice for protection of rarespecies such as those that are threatened or endan-gered, or those for which habitat is not the limitingfactor. Populations of these species need to be main-

Žtained by the ‘fine-filter’ approach Hann et al.,.1994 ; i.e., a number of populations of each such

species, if possible, will have to be protected; andeach of these populations should be maintained witha large enough size andror other special support thatit has a reasonable chance for survival over a reason-able period of time. Special support might have toinclude one or more activities such as protectionfrom excessive competition and predation, assuranceof adequate food and water, provision of habitatconnectors, and artificial supplementation with im-migrants to replenish dangerously low genetic vari-ability. The larger threatened or endangered animalswith longer generation times, lower abilities to in-crease their numbers when environmental conditionsare favorable, and low or high rates of habitat speci-ficity— e.g., the federally listed grizzly bear and

Ž .northern spotted owl Strix occidentalis caurina ,respectively—present very serious large-area re-quirements that also have to be considered by publicland managers.

The need for a fine-filter strategy to ensure thesurvival of endangered, threatened, and special-inter-est animal and plant species means that the ForestService will have to consider development of aprotected area network to supplement its proposedmanagement of vegetation and disturbance patternsat the landscape level. This could presumably bedone by extending its present complex of researchnatural areas, wilderness, and other specially pro-tected areas. Not only are more protected areas ofeach general ecosystem type needed, but there arealso extensive gaps in the ecosystem representationof the existing systems. In fact, this is the case for allof the federal agency protected area systemsŽCrumpacker and Hodge, 1988; Crumpacker et al.,

.1988; Davis, 1988; Noss, 1990b; Scott et al., 1993 .The core reserves of the regional reserve networkdescribed by Noss and Cooperrider provide a usefulmodel for a coordinated expansion of all agencyprotected area systems. An expanded federal pro-

tected area system would also provide additionalbenchmark or ‘control’ areas against which the re-sults of adaptive management ‘experiments’ could becompared.

A Forest Service system of core reserves andbuffers would fit well with the first and last of three

Ž .major forest uses described by Salwasser 1994 asfollows: ‘‘Most affluent cultures acknowledge thatsome forests should be protected for their spiritualand environmental values; some should be managedintensively to produce the wood products that peopleneed and desire; and others should be managed tobalance the protection of environmental values with

Žthe production of desired products’’ also see Hunter.and Calhoun, 1994 .

Development of an expanded fine-filter systemfor threatened, endangered, and special-interestspecies by the Forest Service would require exten-sive changes in the management of some of theirmultiple-use lands. Increased effort would also berequired to develop models that help to estimate thehabitat needed to provide reasonable assurance of

Žviability for such species see Boyce, 1992; Schemskeet al., 1994; Norton, 1995; but also see Doak and

.Mills, 1994; Harrison, 1994; May, 1994 . Theseactions would appear to be necessary even if theForest Service goal to ‘‘sustain populations of all

Žnative plants and animals’’ USDA Forest Service,.1994b should have to be accomplished within a

landscape matrix that contains relatively largeamounts of unnaturalness.

4. Political prospects for ecosystem management

Many members of the present US Congress areunlikely to favor implementation of ecosystem man-agement by the Forest Service and other federal land

Žmanagement agencies e.g., see Hansen, 1994;.Murkowski, 1995 . Instead, they favor a reduced

federal role in management of the public lands,which is the opposite of what would be needed if theForest Service and other federal agencies were toparticipate in development of the kinds of regionalreserve networks that would be important for main-taining US biodiversity. Although some of thesemembers do support using some public lands forpreservation of valuable natural areas, they argue for


transfer from federal authority of much of the multi-ple-use lands that would be needed to form thecritical buffer zones and connectors in regional re-serve networks. In addition, many would be unlikelyto support an extensive effort by the Forest Serviceto maintain or restore historic vegetation and distur-bance patterns on the landscape.

Because the federal ecosystem management initia-tive is based primarily on executive branch directivesand lacks a government-wide legislative mandateŽ .Keiter, 1994a,b it could be easily reversed byanother federal administration. Survival of theecosystem management philosophy is, however, a

Ž .much different matter. Shepard 1994 has argued inthis regard that ecosystem management should notbe viewed as ‘‘a haphazard or frenetic attempt tofind management answers or a public relations cover;ecosystem management should not be viewed as thelatest flavor-of-the-month. Rather, these terms cap-ture a clear evolution of thinking and on-the-groundmanagement as the silvicultural implications of 20years of scientific findings are joined with emergingappreciation of changed sociological, political, andeconomic circumstances.’’ 1

Ecosystem management is actually the secondmajor response of the US federal government in thiscentury to large-scale social and political controversy

Žsurrounding the use of American forests Kennedy.and Quigley, 1994; Shepard, 1994 . The first re-

sulted in the creation of the Forest Service in theGifford Pinchot era, following the close of the Amer-ican frontier and the greatly increased industrializa-tion, urbanization, and forest exploitation of the late19th Century. World War II and the post-war eco-nomic boom of the mid-20th Century created anenormous demand for timber products, and the For-est Service shifted from a custodian and protector toa timber supplier. As a result, timber harvest rosealmost 800% between 1941 and 1971, i.e., from 1.5

Ž .to 11.5 billion board ftryr Steen, 1976 .Ecosystem management is, therefore, a clear and

understandable response by the Forest Service to thedesires of the American public in the late 20th

1 Examples of the ‘terms’ referred to by Shepard are ecosystemmanagement, new forestry, new perspectives, and adaptive forestmanagement.

century to control harvests of natural resources andattendant pollution, loss of biodiversity, and therapidly decreasing naturalness of the national land-scape. The way had actually been indicated almost ahalf-century earlier by the Forest Service’s secondŽ .first? most influential member, Aldo Leopold.Leopold began as a Pinchot disciple and later arguedin some of the most moving prose in environmentalliterature that the primary goal of land managementshould be to maintain the health of natural systems

Ž .and ecological processes Leopold, 1949 .Ecosystem management is an environmental ethic

Ž .that lies between the extremes of 1 steady-stateŽ . Ž .economics Daly, 1991 and 2 maintaining the

status quo or reducing the current emphasis on envi-ronmental quality as it is understood through muchof the federal and state environmental legislation thathas been enacted in the United States since the1960s. The steady-state approach would take imme-diate steps to halt economic growth, shift majorwealth from developed to developing countries, stopglobal human population growth, curtail consump-tion of energy and materials in the developed worldand raise it above poverty levels in the developingworld, and put quotas on the use of nonrenewableresources until they can be replaced with renewableresources. Maintenance of the status quo or reducingthe present emphasis on environmental quality wouldprobably differ only in the speed with which biodi-versity continues to be lost, and the natural environ-ment is converted to a largely artificial, exotic condi-tion. The evidence on which this prediction is basedrepresents one of the most important contributions todate of the science of conservation biology.

5. Consequences for biodiversity of not imple-menting ecosystem management

5.1. Insight from conserÕation biology

Use of population viability models to aid in therecovery of endangered and threatened species, alongwith earlier attempts to apply island biogeographymodels to the design of specific nature reserve sys-

Žtems, has led some scientists e.g., see Doak and.Mills, 1994; Harrison, 1994 to suggest that conser-

vation biology is essentially an empirical science,


with little to offer in the way of powerful generaliza-tions and guidelines. It is therefore instructive toconsider some previous work in conservation biol-ogy that has led to valuable guidelines with respectto the amount of habitat needed to maintain biodiver-sity. The most important thing about these studies isthat they inform policymakers and managers, in avery general way, about the magnitude of the landarea needed to protect biodiversity. This helps toillustrate that many of our present policies are simplyincapable of preventing a decline in biodiversity anda denaturalizing of the landscape.

5.1.1. Species extinctions in national parksAn important concept that follows from island

biogeography theory is based on the study of land-bridge islands that were formerly connected to acontinental mainland and which have become insu-larized over the past 10,000 to 20,000 years bysea-level rise following the melting of glaciers and

Žthermal expansion of oceans MacArthur and Wil-.son, 1967; Wilcox, 1980 . Newly-formed, land-

bridge islands are supersaturated with species; i.e.,they contain more species at first than they canmaintain over time, because they are no longer anintegral part of the mainland. A relentless bioticdecay process follows that is dominated for someperiod of time by species extinction. The rate ofspecies loss is expected to be larger on the smallerislands.

Although continental protected areas are not asisolated from one another as oceanic land-bridgeislands, they are surrounded by a habitat matrix thathas been modified in many ways by human activi-

Ž .ties. Newmark 1987 used this analogy to test thehypotheses that, for a subset of all mammals innational parks or closely associated groups of such

Ž .parks in western North America, 1 mammalianŽextinctions as evidenced by natural disappearance

from a park at some time following the park’s.establishment would exceed natural recolonizations,

Ž .2 the extinction rates would be higher for smallerparks such as Bryce Canyon and Crater Lake thanfor larger ones such as Grand Canyon and Yellow-

Ž .stone–Grand Teton, and 3 given approximatelyequal-sized parks, species loss would be higher for

Žolder than for younger parks the oldest individual

.park is Yellowstone, which was established in 1872 .Each of these predictions was verified, although it

Ž .was later suggested Newmark, 1995 that at least apart of the data might be better interpreted as havingresulted from subpopulation extinctions within ametapopulation framework. This latter considerationis important because it views parks as subpopula-tions of a regional metapopulation, thereby reempha-sizing the potential importance of federal multiple-uselands in future reserve networks.

Ž .Newmark 1987, 1995 also showed that initialŽspecies population size i.e., at the time of park

.establishment was a good predictor of a species’survival time, with initially smaller mammalianspecies populations going extinct more rapidly. Onlythe largest park group, Kootenay–Banff–Jasper–

Ž 2 .Yoho 20,736 km , in Canada, which was estab-lished on average in 1899, has had no natural mam-malian species extinctions. These findings, alongwith surprisingly high post-Pleistocene mammalianextinction rates on true land-bridge islands such as

Ž .Borneo Wilcox, 1980 , much of which has remainedrelatively unmodified by human activity until re-cently, provide strong evidence that no park in theworld is large enough to prevent non-human related,local extinction of at least some mammalian species.This provides a compelling argument for carefulmanagement of mammalian species, and probablymany others, to prevent human- and nonhuman-re-lated extinctions both within parks and in the less-protected matrix of multiple-use and private landssurrounding parks.

Ž .Newmark 1985 estimated the biotic boundariesnecessary to maintain minimum viable populationsŽ .MVP’s of the largest terrestrial, non-flying, mam-malian species in eight of the largest western NorthAmerican parks or closely associated park groups.

Ž .He did this by using 1 50 individuals as a verycrude estimate of the minimum viable populationsize needed to prevent short-term, nonhuman-relatedloss of an isolated species population due to inbreed-

Ž .ing depression and 2 500 as a crudely estimatedminimum size for preventing an isolated population’snonhuman-related loss of ability to adapt to environ-mental change over the longer term, and then com-

Ž .bining these MVP values with 3 the estimatedhome range of each mammalian species in the analy-

Ž .sis and 4 the areal extent of the entire watershed of


each park or park group. 2 The biotic boundaries forseven of the eight parks or park groups were foundto be 1.2 to 9.6 times greater than their legal bound-aries for an MVP of 50 and 6.0 to 96.0 times greaterthan their legal boundaries for an MVP of 500.Species used for these estimates, depending on thepark or park group, were grizzly bear, mountain lionŽ . Ž .Felis concolor , and wolverine Gulo gulo .

Other, and some more recent, theoretical andexperimental studies indicate that the actual censuspopulation sizes needed to maintain isolated viablenatural populations for many species over the longerterm may need to be on the order of 10,000 or more

Ž .individuals, rather than 50 to 500 Lande, 1995 .Although this would greatly increase the area re-quirements for the mammalian species used by New-

Ž .mark 1985 to estimate biotic boundaries, his origi-nal conclusions remain unaltered: ‘‘There are proba-bly no remaining regions in western North Americawhere there are expanses of wildlands of sufficientsize in which it will be possible to design nationalparks so that the legal and biotic boundaries of apark are congruent. In addition, because of the enor-mous potential size of the biotic boundaries, it maybe both politically and economically impractical topurchase the necessary lands. Cooperative forms ofland management between the national parks andadjoining public and private lands will be necessary’’.Lest these results seem too gloomy, it is important tonote that enlightened, professional management ofpopulations and habitats, across political boundaries

Žas necessary, should be and has been, at least in the.short term able to compensate for some of the large

areal requirements embodied in Newmark’s projec-tions.

5.1.2. Relationship of species population size to parksize

Ž .Schonewald-Cox 1983 estimated the relation-ship between park area and census population sizefor a wide range of mammalian species in temperateand tropical regions of North America, South Amer-ica, Europe and Africa. Surprisingly large, relatively

2 For derivation of the estimates of 50 and 500, see Franklin,1980; Soule, 1980; Lande and Barrowclough, 1987.´

homogeneous, and highly statistically significant cor-Žrelations were found for large carnivores bears,

.canids, and large cats , as well as for large herbi-Ž .vores deer, elk, wildebeest, elephant, etc. and small

Ž .herbivores certain rodents, rabbits, etc. . The analy-sis indicated that, at least for the short term, parksgreater than the following sizes would be needed tomaintain 1000 individuals of the following types ofmammals: small herbivores—1 km2; large herbi-vores—100 km2; and large carnivores—10,000km2. 3

A much more extensive analysis involving therelationship between study site area and census pop-ulation size of medium to large carnivores was sub-sequently conducted by Schonewald-Cox et al.Ž .1991 . Results supported the earlier suggested needfor more than 10,000 km2 to maintain 1000 individ-uals; in fact, areas of at least 20,000 to 40,000 km2

were indicated for some large carnivore species.Future increases of habitat fragmentation within parkswould generally be expected to increase these area

Žrequirements Schonewald-Cox and Buechner, 1991,.1992 .

5.1.3. ConserÕation networksThe very general and admittedly crude area values

for large carnivores obtained from the analysis ofŽ .Schonewald-Cox 1983 were used by Salwasser et

Ž .al. 1987 to estimate the size of US conservationnetworks needed to maintain populations of largecarnivores over at least the short term. Salwasser etal. considered a conservation network to be the sumof the major land management agency units, includ-ing other units than federal in some cases, surround-ing an existing higher-protection core that consists,e.g., of one or more national parks. They found thateight of the nine national park core areas included intheir analysis were not large enough to protect largecarnivores, whereas all but one of the conservationnetworks might be. To give some idea of relativesizes, the Yellowstone Conservation Network, con-

3 Note that the Yellowstone–Grand Teton park group is approx-imately 10,000 km2 and it is still not large enough to accommo-date over the long term an isolated population of grizzly bears,according to Newmark’s analysis.


sisting of eight national forests and two nationalrefuges surrounding the Yellowstone–Grand TetonNational Park core, is 55,580 km2 compared to thecore area of 10,240 km2. The Southern AppalachianHighland Conservation Network, consisting of fivenational forests surrounding the Great Smokies Na-tional Park core, is 23,990 km2 compared to the corearea of 2080 km2. This very preliminary analysiswas intended primarily to demonstrate the concept ofconservation networks. It used only National Park

ŽService lands for cores excluding, e.g., wilderness.areas in national forests and assumed that ‘ideal’

cooperation would be obtained among all of the landmanagers in a network. Ideal cooperation might re-quire modification of certain activities such as clear-cutting, road building, mining, grazing, water devel-opment, or high-density recreation in certain parts ofthe national forests surrounding a core. The intent ofthe authors was to ‘‘begin to view networks of landsunder different ownerships and management policiesas being able to sustain the structural and functionaldiversity of entire ecosystems while providing asteady flow of resources to local and regionaleconomies’’.

5.2. Policy implications and the future of biodiÕer-sity

Analyses such as those conducted by Newmark,Salwasser et al., and Schonewald-Cox and associatesŽ .see preceding parts of Section 5 , together withdetailed ecological studies on grizzly bears in the

Ž .Yellowstone National Park region Craighead, 1979 ,provide a powerful argument for ecosystem manage-ment, especially with respect to the idea of managingover time and space and across political boundariesto maintain biodiversity. The type of very crudemodeling and prediction accomplished by these in-vestigators does not produce risk estimates in termsof probability for survival of a species populationover a specified period of time, nor does it attempt toprovide detailed area requirements for specific habi-tat types. Instead, it contributes to a desirable goal

Žsuggested by Fitch personal comm. from J.S. Fitch,.Dept. of Political Science, U. of Colorado, Boulder ,

i.e., to warn policymakers when there is reason to

believe that policies under consideration are likely tobe unsustainable. 4

Those who argue against the implementation ofecosystem management may believe that environ-mental quality will be better served by less govern-ment restraint on how individuals and corporationsuse environmental resources. The more likely resultwill be a ‘tragedy of the biodiversity commons’.

Ž .Hardin 1968 has argued in this regard that ‘‘Eachman is locked into a system that compels him toincrease his herd without limit—in a world that islimited . . . Ruin is the destination toward which allsuch men rush, each pursuing his own best interest ina society that believes in the freedom of the com-mons. Freedom in a commons brings ruin to all’’.Native species are a unique type of global commonsin that once they are lost they cannot be expected tooccur again; in fact, plant and animal species cannotreasonably be expected to be replaced by new nativespecies within a time frame that has any meaning forhumans. Dependence on the marketplace to signalthat a particular, naturally occurring species has be-come rare, and therefore valuable enough to warrantprotection, runs the high risk that its population orpopulations will no longer be minimally viable. Thisalready appears to be one of the main weaknesses ofthe Endangered Species Act, which is not evensupposedly driven by market factors. By the timemost threatened or endangered species are broughtunder protection through listing, their actual censuspopulation sizes are on the order of 100 for plants

Ž .and 1000 for animals Wilcove et al., 1993 . Thesenumbers now appear to be well or far below sizesthat would be expected to be minimally viable under

Žnatural conditions i.e., without special human sup-. Žport for reasonable periods of time e.g., hundreds

to thousands of generations involving hundreds to.thousands of years for various kinds of species

Ž .Lande, 1995 .From the standpoint of natural environmental

quality, de-emphasis of ecosystem management canbe expected to interact in a negative and synergistic

4 In this instance, the unsustainable policies involve land man-agement confined within political boundaries of national forests,BLM resource areas, national parks, and national wildlife refugesthat will most likely lead to continuing losses of biodiversity.


fashion with increased human population growth inthe United States. It is very likely in this situationthat the per capita amount of forests and woodlandsof all kinds, public and private and natural andnon-natural, will continue to decrease. Assuming 10million persons in the United States in 1700 AD, theper capita area of these kinds of ecosystems hasdecreased from 45 ha in 1700, to 1.2 ha at presentŽ .i.e., from 111 acres to 3 acres . This compares witha global per capita decline from 30 ha to 0.75 haŽ .from 74 acres to 2 acres over the same period of

Ž .time Salwasser, 1994 . The United States has alsoexperienced large decreases in other major types ofterrestrial and wetland ecosystems such as grass-

Žlands, shrublands, and marshes Crumpacker, 1985;Crumpacker and Hodge, 1988; Crumpacker et al.,

.1988; Noss et al., 1995 .

5.3. Possible effects on ecosystem serÕices

If something like ecosystem management is notincreasingly practiced in the United States and else-where, the ability of the natural environment tomaintain air and water quality, soil stability andfertility, flood control, pest control, a moderate cli-mate, and other ecosystem services is very likely todecrease. The amount of decrease will depend onhow much natural environment is lost, and on howadequately and rapidly human ingenuity can providenative species monocultures, exotic species, and abi-otic technologies to replace the native species andnatural processes. An extremely negative case could

Ž .be unbelievably expensive Avise, 1994 , therebyproviding a general warning about the costs associ-ated with less extreme situations.

Loss of natural ecosystem services is a majorconcern of ecological economists who believe thatslowly changing ecological systems will be unable to

Žmaintain their integrity e.g., adequate functional.capabilities and resilience if the natural world is

Ž .depleted too rapidly Haskell et al., 1992 . Theyview ‘sustainability’ as the amount of human con-sumption that can be continued indefinitely withoutdegrading capital stocks or, in an important sense,

Žjustice with respect to future generations Costanza,.1995 . Even though some mainstream economists

believe that human knowledge and technology can

Žsubstitute for loss of natural capital e.g., see Sagoff,.1995 , ecological economists would question if this

could be done rapidly enough to prevent seriousŽenvironmental degradation in the interim El Serafy,

.1991 .If the integrity of the global environment is not

maintained, while using it for human life and activi-ties, impoverishment is likely to be very serious in

Ž .many parts of the world Woodwell, 1990 . Peopleworking together to sustain the quality of life in theircommunities, in concert with and aided by environ-mental quality regulations, offers a possibility foravoiding this situation.

6. A potential solution: integration of ecosystemmanagement into human communities

Implementation of ecosystem management in theUnited States will require a willingness to live in amore sustainable fashion and also, for conservationbiologists, a much closer concern for the effects of

Žconservation measures on human communities e.g.,. Ž .see Yaffee, 1994; Roush, 1995 . Keiter 1994a has

noted that because the impetus for ecosystem man-agement is dependent on scientific insight from dis-ciplines such as ecology and conservation biology,some proponents believe that scientific experts shouldtell the public what to do. Yet the concept of ecosys-tem management is value-based and owes much ofits currency to societal values concerning biologicaldiversity and species preservation. The most impor-tant problem will be to integrate scientific data withpublic values. As long as humans are part of ecosys-tems, meaningful participatory decision-making mustbe an essential part of ecosystem managementŽ .Gerlach and Bengston, 1994 . Serafin and SteedmanŽ .1991 have even argued that the concept of ecologi-cal integrity does not exist outside of human valuejudgments, unlike, e.g., the concepts of gravity andgeneral relativity.

6.1. Community action groups

The best chance for implementing the Forest Ser-vice type of ecosystem management, i.e., manage-ment with a priority to sustain the integrity of


ecosystems while producing desired goods and ser-vices, may lie with community groups that representeither commodity and development or preservationinterests but which share some ethical values relatedto biodiversity and the ‘land’. This fits well with thecurrent situation in which the Forest Service has noclear legal mandate to implement ecosystem man-

Ž .agement Keiter, 1994a,b and therefore needs tofind a socially accepted balance between ecological

Ž .and commodity objectives Swanson et al., 1994 . Italso fits with the approach of local groups who areusing conservation biology principles to promotemaintenance of biodiversity through development ofregional reserve network plans for The Wildlands

Ž .Project Noss, 1992 . For the latter, the priority ofecosystem management is to maintain naturalecosystem integrity while producing desired goodsand services. It may be possible for the commoditydevelopment and natural biodiversity interests to findsome common ground in a shared land ethic.

Ž .Chapman 1995 has described the ‘place-based’emphasis of community and regional consensusgroups that are beginning to spring up in the westernUnited States. Instead of wise use, property rights,and many environmental organizations that promotespecial interests, the purpose of these consensusgroups is to identify and pursue solutions that are inthe best interest of their communities. This willusually require compromises because ‘‘Nobody ex-pects to get everything they want. Everybody hopesto get more than they would had they not partici-pated. And they hope whatever they get will be morelong-lasting’’. The intent is for local economies tocontinue to use the public land resources, as long astheir uses are sustainable or restorative. This willrequire a better understanding by everyone of envi-ronmental limits and carrying capacity. Consensusgroups suffer from various problems related to lackof authority and funding, including the tendency ofthe present public land management planning pro-cess to encourage individual rather than communityresponses to environmental issues. Consensus groups,therefore, usually favor decentralization of public

Ž .agency decision-making authority Chapman, 1995 .To an important extent, the major, shared justifi-

cation for protecting natural biodiversity among allinterest groups is likely to be perceived as ethical

Žand cultural rather than ecological e.g., ecosystem

. Ž .services and economic e.g., commodities . Thepleasure of being able to experience a better qualityof life, including opportunities to interact with rea-sonably natural environments, is a major force be-hind current immigration to the interior west of the

Ž .United States Rasker, 1994 . It is also likely to bean important reason why many ‘natives’ do not wantto leave. If the main, commonly shared justificationfor protecting natural biodiversity is actually ethicaland cultural, then management to sustain the in-tegrity of natural ecosystems may well be achievedonly by integrating scientific data with human val-ues.

Ž .The Man and the Biosphere Program MAB ofthe United Nations Scientific, Educational, and Cul-

Ž .tural Organization UNESCO represents one of theearliest attempts in the modern environmental age toemphasize the community approach to maintenanceof biodiversity. Since its inception in 1971, MABhas promoted the idea that it is possible to achieve asustainable balance among the conservation of bio-logical diversity, economic development, and cul-tural values. The main vehicle for demonstrating,refining, and implementing this concept is MAB’s

Žinternational network of biosphere reserves U.S..Man and the Biosphere Program, 1994 . A biosphere

reserve is an internationally recognized area withinwhich the biodiversity characteristic of the ecosys-

Ž .tem s of a region is preserved and opportunities arealso provided for environmental research and educa-tion, and for sustainable types of economic develop-

Žment i.e., development that sustains both the econ-.omy and the natural environment .

The biosphere reserve concept has served as amodel for innovative attempts by the US NatureConservancy to protect entire ecosystems from envi-ronmental degradation. Protected areas are estab-lished within which the most highly valued biodiver-sity of a region is concentrated and around or withinwhich people live in ‘buffer’ andror ‘transition’zones, where sustainable types of economic activitiesare encouraged. US examples include the VirginiaCoast Reserve on the Atlantic Ocean near the mouthof Chesapeake Bay, a tallgrass prairie in Northeast-ern Oklahoma, the San Pedro River and AnimasMountains area of southeastern Arizona and south-western New Mexico, and the hill country of central

Ž .Texas The Nature Conservancy, 1991 . In all in-


stances, these programs involve working with localcitizens, local governments, and often, as well, withcorporate and environmental group stakeholders.These efforts are building constituencies of eco-nomic and conservation interests through long-term,intensive involvement at the community level.

The Forest Service began to change the way itdeals with community issues in the early 1990s. Thishas evolved from emphasizing ‘community stability,’as linked to sustained commodity yields, to promot-

Ž . 5ing a ‘rural development’ approach Bates, 1993 .The latter includes working with rural people andcommunities to develop resource-based ventures thatcontribute to their economic and social well-being.As noted by Bates, this type of planning focuses onenhancing the productive capacity of rural Americaover the long-term and emphasizing that, e.g.,‘‘maintaining timber-related employment should bea less important goal than diversifying a local econ-omy and building alternative sources of income andemployment’’. Bates describes initiatives of this sortin Kremmling, Colorado and Dubois, Wyoming, aswell as community-based efforts that have beenstimulated by non-governmental organizations, suchas the Grand Canyon Trust’s involvement on theColorado Plateau and that of the Wilderness Societyin Oregon and Washington.

An initiative begun in 1989 by The KeystoneCenter of Keystone, Colorado brought a wide arrayof public and private interests together to considerthe problem of conserving, protecting and restoring

Žbiological diversity on US federal lands The Key-.stone Center, 1991 . The participants in this dialogue

concluded that biological diversity is necessary forthe continued health and development of humans;current positive, public and private efforts to con-serve biological diversity are not completely ade-quate; federal lands can play a significant role inconservation of biological diversity; and the changesneeded to sustain biodiversity can be accomplishedwhile allowing significant human use of natural re-sources on federal lands.

5 For an expanded version, of Bates, 1993 see Public LandLaw Review, spring 1993, University of Montana School of Law,Missoula, MT.

A more recent Keystone initiative is consideringhow to develop community-based efforts that pro-

Žmote ecosystem management The Keystone Center,.1995 . Meetings in 1995 have been held in Tucson,

AZ; Bangor and Castine, ME; Seattle, WA; and SanDiego, CA. Core members of the Keystone ‘Di-alogue’ attended each meeting, during which theyusually toured key sites in the region and met withcommunity-based stakeholder organizations. Exam-

Ž .ples of such organizations include: 1 The MalpaiBorderlands group in southern Arizona, which con-sists of a small number of ranchers and environmen-talists who are concerned about landscape fragmenta-tion, declining productivity, and loss of biologicaldiversity associated with encroachment of woodyspecies on grasslands; they meet periodically withpersonnel from public agencies, The University ofArizona, The Nature Conservancy, and The Animas

Ž .Foundation; 2 The Yakima Resource ManagementCooperative Group, consisting of schools, utilities,agricultural producers, public and private corpora-tions, the Yakima Indian Nation, environmentalgroups, and governmental representatives; this groupis interested in sustainable development, environ-mental health, and community values in the Upper

Ž .Yakima River Basin of central Washington; and 3The Natural Communities Conservation PlanningProgram, involving federal–state–local agencies, de-velopers, environmental organizations, and privatecitizens; this group is developing habitat conserva-tion plans for a range of species in southern Califor-nia.

The Keystone Dialogue Group actually met withindividuals involved in approximately 30 initiativesin 1995 that were similar to, and included most of,those mentioned above. Examples of important points

Ž .raised at these meetings are: 1 redefining the roleof government to give community stakeholders an

Ž .incentive to launch processes; 2 definition of aŽstakeholder a person or group who must be included

. Ž .for a solution to be viable, endure and persist ; 3Žthe concept of internal stakeholders dependent on

. Žcohesion and external stakeholders encouraged to. Ž .buy into the process ; 4 support and latitude from

superiors for agency personnel who want to be inti-Ž .mately involved in the process; 5 the appropriate

Žrole for scientists e.g., less time should be spent onthe technical ‘what is’ part of the process and more


on ‘what ought to be,’ which is not resolvable by. Ž .science ; 6 the need for more financial incentives

and less legislative disincentives with respect to localideas that have the potential to improve the environ-

Ž .ment; 7 the use of stakeholders to help in monitor-Ž .ing the results of management activities; and 8 the

potential value of more professional risk-takingwithin federal bureaucracies on behalf of innova-tions.

Examples of products considered by the KeystoneDialogue Group as a result of their deliberations are:Ž .1 a report to the US Congress suggesting changes

Žin some federal statutes e.g., the Federal Advisory.Committee Act and the Sherman Antitrust Act that

would facilitate community–agency joint planning,Ž .and 2 a report on the potential role of the market-

place in ecosystem management.

6.2. Some policy and economic considerations

The recent increase in community-based groupsinterested in better integration of human values inpublic land management appears to offer an impor-tant means by which federal agencies can obtainguidance with respect to ecosystem management,especially in regard to the balance between manag-ing for natural ecosystem integrity and human needs.This has led some persons to suggest that ecosystemstewardship might be a more appropriate name thanecosystem management, as the former connotes the

Židea of people having responsibility McVicker,.1996 .

Many locally dominated decisions of the sortdesired by most community action groups wouldundoubtedly vary in the extent to which they ad-vance natural ecosystem integrity. The approach isrisky from that standpoint because it could simplyresult in a tragedy of the biodiversity commons on ahigher spatial scale, e.g., adjoining national forests orBLM resource areas might end up being managed indifferent ways that would not promote the broad-scalenatural or even seminatural integrity of ecosystems.Alternatively, the more successful of these activitieson certain land management units might serve asprototypes that would influence their adoption inother units. A somewhat similar approach to manag-ing something as complex as ecosystems has been

Ž .suggested by Brunner 1993 with respect to the US

Global Change Research Program and its ability toprovide useful information for federal policy forma-tion. He argued that decentralized policy teams mightmake the most efficient contributions in this regard.Each team could simplify the national problem byfocusing on those scientific projections and socio-political considerations that are most important in itsown locality over the next few years. Progress wouldnot then depend on reducing scientific uncertainty ona national or global scale, but rather on a series of‘parallel local actions designed in part to clarifyexpectations, preferences, and political realitiesthrough experience.’ Whether this would work withnatural resources and biodiversity is, of course, un-known but the adaptive management process couldserve as a guide.

It is important to note that an underlying philoso-phy of conservation biology is prudence; i.e., due touncertainty about the behavior of ecosystems, it is

Ž .best to err on the side of preservation Noss, 1994 .This is one reason why it would be preferable tohave a clear legal mandate for protection of biodiver-sity as a central requirement of public land manage-

Ž .ment Keiter, 1994b . Such legislation would need toaccommodate the constitutional rights of private

Ž .property owners Keiter, 1994b . This is a compli-cated area that concerns the degree to which propertyowners should be able to use their property withoutcausing harm to other people and the environment.

Ž .But within those limits, Freyfogle 1995–1996 hassuggested that compensation should be provided tolandowners who are affected by the need to maintainregional ecosystem integrity and that they should notbe required to open their lands to public use.

A promising way to proceed, then, might be toobtain some broad legislative guidance concerningthe importance of biodiversity to the public welfare,within which local community decision-making could

Ž .play a major role. As Noss and Cooperrider 1994have observed, top-down guidance would providecontext, while bottom-up involvement would providecare and local knowledge. Ultimately, the new legis-lation would need to incorporate a federal endorse-ment of biodiversity conservation as a major objec-tive of federal land management; i.e., there wouldneed to be a tilt from federal agency anthropocen-trism toward a somewhat more biocentric goal forecosystem management. The legislation could be


implemented as broad guidelines rather than strictrules. This would allow managers to deviate from theguidelines if justified by, e.g., compelling local com-

Ž .munity circumstances Keiter, 1994a .A method for addressing the negative effect of

some current federal statutes on community–agencyplanning and the potential positive effect of market-based incentives on ecosystem management—priori-

Žties identified by the Keystone Dialogue Group The.Keystone Center, 1995 —has been proposed by

Ž .Lippke and Oliver 1994 . It would involve a differ-ent legislative approach that would create an eco-nomic tradeoff system. Public and private land man-agers within a landscape unit would make competi-tive bids to a public body charged with using publicfunds to protect ecosystem values. A typical bid

Žmight be to produce certain forest ‘structures’ e.g.,.stands of certain vegetation types and seral stages in

Ž .order to promote both market timber and nonmar-Ž .ket ‘ecosystem’ values.

Advantages of a competitive bidding process,compared to a strictly regulatory or a ‘guidelines’

Ž .approach, might include: 1 removing the need forland managers to cooperate in violation of federal

Ž .trade laws and other statutes; 2 encouraging landowners to do things of public value that would not

Ž .otherwise be personally beneficial; 3 ensuring thatpublic funds would be spent as efficiently as possi-ble, using a market approach to determine the costs

Ž .involved in producing ecosystem values; and 4producing both market and nonmarket outputs, with-out the need for substitutions from competing suppli-ers that would contribute to an overall loss of global

Ženvironmental quality e.g., by stimulating tropicaldeforestation, oil drilling in the Gulf of Mexico andthe arctic, and mining of minerals in South America

.and Africa .A hypothetical example of the above type of

market-based ecosystem management for 15,000acres of existing forest stand structures on nonfederallands in eastern Washington has been investigated by

Ž .Oliver 1992 . The analytical results indicated thatbiodiversity and general forest health could be in-creased while incurring management costs that werenot much higher than the cost savings related tocreation of new jobs and reduction of unemploymentcompensation in the local communities.

7. Conclusion

Ecosystem management from the perspective ofconservation biology is biocentric because it tends toplace primary emphasis on sustaining the integrity ofnatural ecosystems. The US Forest Service view ofecosystem management also places primary empha-sis on sustaining ecosystem integrity but favors ananthropocentric approach in which an array of publicpreferences will determine the extent to which utili-

Ž .tarian commodities, recreation, etc. and naturalŽ .biodiversity values will be favored.

One important suggestion for implementingecosystem management is the creation of regionalreserve networks for biodiversity, which is popularamong many conservation biologists. Another is theUS Forest Service’s suggestion for using timbermanagement and other forest practices to mimichistoric patterns of disturbance and vegetation on thelandscape, in order to help maintain biodiversity,while simultaneously providing for traditional multi-ple uses such as timber, grazing, recreation, andwildlife. These ideas are not mutually exclusive,could potentially be complementary, and are viewedas long-term, very challenging efforts.

Some important political interests do not presentlyappear to favor either of the above strategies. Never-theless, compelling scientific evidence from conser-vation biology argues that failure to apply some sortof ecosystem management-type of approach to theremaining natural and seminatural parts of the USlandscape will result in the continued loss of naturalbiodiversity. Even failure to maintain the status quo,which includes only the beginnings of managementto sustain natural ecosystem integrity, is likely tocause additional loss of naturalness and result even-tually in a ‘tragedy of the biodiversity commons’.

To discontinue implementation of the present For-est Service and other agency goals of producingpublicly desired resources within the constraint ofsustaining ecosystem integrity is likely to have im-portant ecological effects, regardless of the emphasisplaced on naturalness. That is, services such as main-tenance of air and water quality, provided by theremaining mix of natural, seminatural, and exoticecosystems, are likely to be interfered with. Theeffect of this on US welfare would depend in part on


the success and cost of the human fixes that wouldpresumably be attempted.

Creation of broad legislative guidelines for main-tenance of biodiversity, within which the concernand knowledge of local communities can play amuch greater role than previously in determininglocal to regional land management, offers a potentialmeans of sustaining both ecosystem integrity andlocalrregional economies. Even this approach isrisky with respect to sustaining natural ecosystemintegrity but can, perhaps, be guided by knowledgeobtained from the practice of adaptive ecosystemmanagement. The degree to which a meaningfulamount of natural biodiversity survives would proba-bly still depend on the degree to which stakeholdersin a community share ethical and cultural valuesrelated to maintenance of the natural environment.Prospects for success would be strengthened by theextent to which financial incentives could be offeredfor natural biodiversity maintenance and by respectfor private property rights, as long as their exercisedoes not involve loss of natural environmental sus-tainability.

Whether or not the US public wants to manageecosystems to maintain their natural integrity, i.e.,practice the conservation biology type of ecosystemmanagement, is one of the most important ‘quality oflife’ questions that we need to consider. Put slightlydifferently, we might ask, ‘‘Do we want to live in alargely exotic and artificial environment during muchof the 21st century or in an environment that allowsreasonably easy access to native plants and animalsin reasonably natural ecosystems and landscapes?’’This question needs to be debated openly and ac-tively now, in order that the decision can be madeknowingly and intelligently. If this is not done, itseems very likely that, as mentioned above, thetragedy of the commons will provide the defaultanswer and it will be ‘exotic and artificial’.

The United States is one of only a few industrial-ized nations that still retains a large biodiversitycommons, and the extent of this diversity, fromalpine and arctic to tropical biomes, and from forests,grasslands, and deserts to wetland and aquatic habi-tats, is presently unsurpassed by any nation in theworld. In an important way, this is our last nationalfrontier. Ecosystem management, as presently visual-ized by many conservation biologists, offers a ratio-

nal means of attempting to sustain this nationalheritage.

Acknowledgements

This paper is a shortened, and otherwise some-what modified, version of Paper PL03 of the PublicLand Policy Discussion Paper Series of the NaturalResources Law Center at the University of Colorado

Ž .at Boulder 1996 . The literature review for thatpaper and for the present one was completed onMarch 15, 1996. I thank the Natural Resources LawCenter for financial, editorial, and secretarial sup-port. Michael Gheleta, Bob Keiter, Charlie Malone,Teresa Rice, and Hal Salwasser read completely anearlier draft of Paper PL03. I am especially indebtedto Hal Salwasser for detailed comments. All madeimportant criticisms but I am entirely responsible forthe final version of both papers. I also benefittedfrom discussions and information sharing with JimCronin, Paul De Morgan, Ed Grumbine, Tom Hobbs,John Humke, Will Moir, Christine Schonewald, TimSeastedt, and Nicole Silk.

References

Ž .Agee, J.K., Johnson, D.R. Eds. , 1988. Ecosystem Managementfor Parks and Wilderness. Univ. of Washington Press, Seattle,WA.

Alpert, P., 1995. Incarnating ecosystem management. Conserv.Biol. 9, 952–955.

Anderson, J.E., 1991. A conceptual framework for evaluating andquantifying naturalness. Conserv. Biol. 5, 347–352.

Angermeier, P.L., Karr, J.R., 1994. Biological integrity versusbiological diversity as policy directives—protecting biotic re-sources. BioScience 44, 690–697.

Avise, J.C., 1994. The real message from Biosphere 2. Conserv.Biol. 8, 327–329.

Baskerville, G., 1985. Adaptive management—wood availabilityand habitat availability. Forestry Chronicle 61, 171–175, Citedin Everett et al., 1994.

Bates, S., 1993. Discussion paper: public lands communities.Western Lands Report No. 5, Natural Resources Law Center,Univ. of Colorado School of Law, Boulder, CO.

Ž .Bourgeron, P.S., Engelking, L. Eds. , 1992. Preliminary compila-tion of a series level classification of the vegetation of thewestern United States using a physiognomic framework. Re-port to the Idaho Cooperative Fish and Wildlife Research Unit,Western Heritage Task Force, The Nature Conservancy, Boul-

Ž .der, CO cited in Noss and Cooperrider, 1994 .


Boyce, M.S., 1992. Population viability analysis. Annu. Rev.Ecol. Systematics 23, 481–506.

Brunner, R.D., 1993. Policy and global change research: a modestproposal. Discussion paper No. 75, Center for Public PolicyResearch, Univ. of Colorado, Boulder, CO.

Cairns, J., 1977. Quantification of biological integrity. In: Ballen-Ž .tine, R.K., Guarraia, L.J. Eds. , The Integrity of Water. Office

of Water and Hazardous Materials, US Environmental Protec-tion Agency, US Government Printing Office, Washington,

Ž .DC, pp. 171–187 cited in Noss, R.F., 1990a .Caughley, G., Gunn, A., 1996. Conservation Biology in Theory

and Practice. Blackwell, Cambridge, MA.Chapman, M.M., 1995. Maybe those of us who say it cannot be

done should get out of the way of those who are doing it.Draft of paper related to symposium on Public–Private Part-nerships held at conference on Challenging Federal Ownershipand Management: Public Lands and Public Benefits. NaturalResources Law Center, Univ. of Colorado School of Law,Boulder, CO.

Clark, T.W., Zaunbrecher, D., 1987. The Greater Yellowstoneecosystem: the ecosystem concept in natural resource policyand management. Renewable Res. J., summer, 8–16.

Costanza, R., 1995. Ecological economics: toward a new transdis-Ž .ciplinary science. In: Knight, R.L., Bates, S.F. Eds. , A New

Century for Natural Resources Management. Island Press,Washington, DC, pp. 323–348.

Craighead, F., 1979. Track of the Grizzly. Sierra Club Books, SanFrancisco.

Crumpacker, D.W., 1985. Status and trend of natural ecosystemsin the United States. Report to the Office of TechnologyAssessment, US Congress, National Technical InformationService, Springfield, VA.

Crumpacker, D.W., Hodge, S.W., 1988. Representation of majorterrestrial and wetland ecosystems in the National Park Systemof the United States and comparison with other US national

Ž .land management systems. In: Simon, D.J. Ed. , New Parks:New Promise, Vol. 8 of Investing in Park Futures: A Blueprintfor Tomorrow. National Parks and Conservation Association,Washington, DC, pp. II-1 to II-96.

Crumpacker, D.W., Hodge, S.W., Friedley, D., Gregg, W.P. Jr.,1988. A preliminary assessment of the status of major terres-trial and wetland ecosystems on federal and Indian lands in theUnited States. Conserv. Biol. 2, 103–115.

Daly, H.E., 1991. Steady-State Economics, 2nd edn. with NewEssays. Island Press, Washington, DC.

Davis, G.D., 1988. Preservation of natural diversity: the role ofecosystem representation within wilderness. Paper presented at

ŽNational Wilderness Colloquium, Tampa, FL cited in Noss.and Cooperrider, 1994 .

Doak, D.F., Mills, L.S., 1994. A useful role for theory in conser-vation. Ecology 75, 615–626.

Ecological Society of America, 1995. The scientific basis forecosystem management—an assessment by the EcologicalSociety of America. Prepublication copy, Ad Hoc Committeeon Ecosystem Management, Ecol. Soc. Am., Washington, DC.

Ehrlich, P.R., Mooney, H.A., 1983. Extinction, substitution, andecosystem services. BioScience 33, 248–254.

El Serafy, S., 1991. The environment as capital. In: Costanza, R.Ž .Ed. , Ecological Economics: The Science of Management andSustainability. Columbia Univ. Press, New York, pp. 168–175.

Everett, R.L., Oliver, C.D., Saveland, J., Hessburg, P.F., Diaz, N.,Irwin, L., 1994. Adaptive ecosystem management. In: Jensen,

Ž .M.E., Bourgeron, P.S. Tech. Eds. , Ecosystem Management:Principles and Applications, Vol. II. General Technical ReportPNW-GTR-318, USDA Forest Service, Pacific Northwest Re-search Station, Portland, OR, pp. 340–354.

Ž .Fiedler, P.L., Jain, S.K. Eds. , 1992. Conservation Biology—TheTheory and Practice of Nature Conservation, Preservation andManagement. Chapman & Hall, New York.

Franklin, I.R., 1980. Evolutionary change in small populations. In:Ž .Soule, M.E., Wilcox, B.A. Eds. , Conservation Biology—An´

Evolutionary-Ecological Perspective. Sinauer Associates, Sun-derland, MA, pp. 135–149.

Freyfogle, E.T., 1995–1996. Land ownership, private and wild—aproposed strategy. Wild Earth, winter, pp. 71–77.

Gerlach, L.P., Bengston, D.N., 1994. If ecosystem management isthe solution, what’s the problem?. J. Forestry 92, 18–21.

Grumbine, R.E., 1992. Ghost Bears— Exploring the BiodiversityCrisis. Island Press, Washington, DC.

Grumbine, R.E., 1994. What is ecosystem management?. Conserv.Biol. 8, 27–38.

Hann, W.J., Jensen, M.E., Bourgeron, P.S., Prather, M., 1994.Land management assessment using hierarchical principles of

Žlandscape ecology. In: Jensen, M.E., Bourgeron, P.F. Tech..Eds. , Vol. II, Ecosystem Management: Principles and Appli-

cations. General Technical Report PNW-GTR-318, USDAForest Service, Pacific Northwest Research Station, PortlandOR, pp. 285–297.

Hansen, J.V., 1994. Ecosystem management. Opening statementbefore Joint Oversight Hearing on Ecosystem Management.US House of Representatives, Washington, DC.

Hardin, G., 1968. The tragedy of the commons. Science 162,1243–1248.

Harris, L.D., 1984. The Fragmented Forest: Island BiogeographyTheory and the Preservation of Biotic Diversity. Univ. ofChicago Press, Chicago.

Harrison, S., 1994. Metapopulations and conservation. In: Ed-Ž .wards, P.J., May, R.M., Webb, N.R. Eds. , Large-scale Ecol-

ogy and Conservation Biology. Blackwell, Oxford, UK, pp.111–128.

Haskell, B.D., Norton, B.G., Costanza, R., 1992. What is ecosys-tem health and why should we worry about it? In: Costanza,

Ž .R., Norton, B.G., Haskell, B.D. Eds. , Ecosystem Health.Island Press, Washington, DC, pp. 3–20.

Hoerr, W., 1993. The concept of naturalness in environmentaldiscourse. Nat. Areas J. 13, 29–32.

Holling, C.S., 1973. Resilience and stability of ecological systems.Ann. Rev. Ecol. Systematics 4, 1–23.

Ž .Holling, C.S. Ed. , 1978. Adaptive Environmental Assessmentand Management. Wiley, London, UK.

Hunter, Jr., M.L., 1996. Fundamentals of Conservation Biology.Blackwell, Cambridge, MA.

Hunter, M.L., Calhoun, A., 1994. A triad approach to land useŽ .allocation. In: Szaro, R. Ed. , Biodiversity in Managed Land-


Žscapes. Oxford Univ. Press, New York, cited in Noss and.Cooperrider, 1994 .

Hunter, M.L., Jacobson, G.L., Webb, T., 1988. Paleoecology andthe coarse-filter approach to maintaining biological diversity.Conserv. Biol. 2, 375–385.

Interagency Ecosystem Management Task Force, 1995. Theecosystem approach: healthy ecosystems and sustainable eco-nomics. Vol. II, Implementation Issues. Report of the Intera-gency Ecosystem Management Task Force, Washington, DC.

Ž .Jensen, M.E., Bourgeron, P.S. Tech. Eds. , 1994. Vol. II, Ecosys-tem Management: Principles and Applications. General Tech-nical Report PNW-GTR-318, USDA Forest Service, PacificNorthwest Research Station, Portland, OR.

Jensen, M.E., Everett, R.L., 1994. An overview of ecosystemmanagement principles. In: Jensen, M.E., Bourgeron, P.S.Ž .Tech. Eds. , Vol. II, Ecosystem Management: Principles andApplications. General Technical Report PNW-GTR-318,USDA Forest Service, Pacific Northwest Research Station,Portland, OR, pp. 6–15.

Karr, J.R., Dudley, D.R., 1981. Ecological perspective on waterquality goals. Environ. Manage. 5, 55–68.

Kay, J.J., 1993. On the nature of ecological integrity: someclosing comments. In: Woodley, S., Kay, J., Francis, G.Ž .Eds. , Ecological Integrity and the Management of Ecosys-tems. St. Lucie Press, Delray Beach, FL, pp. 201–212.

Keiter, R.B., 1994a. Beyond the boundary line: constructing a lawof ecosystem management. Univ. Colorado Law Rev. 65,293–333.

Keiter, R.B., 1994b. Conservation biology and the law: assessingthe challenges ahead. Chicago–Kent Law Rev. 69, 911–933.

Kennedy, J.J., Quigley, T.M., 1994. Evolution of Forest Serviceorganizational culture and adaptation issues in embracingecosystem management, In: Jensen, M.E., Bourgeron, P.S.Ž .Tech. Eds. , Vol. II, Ecosystem Management: Principles andApplications. General Technical Report PNW-GTR-318,USDA Forest Service, Pacific Northwest Research Station,Portland, OR, pp. 16–26.

Kessler, W.B., Salwasser, H., Cartwright, C.W. Jr., Caplan, J.A.,1992. New perspectives for sustainable natural resources man-agement. Ecol. Applications 2, 221–225.

Lande, R., 1995. Mutation and conservation. Conserv. Biol. 9,782–791.

Lande, R., Barrowclough, G.F., 1987. Effective populative size,genetic variation, and their use in population management. In:

Ž .Soule, M.E. Ed. , Viable Populations for Conservation. Cam-´bridge Univ. Press, UK, pp. 87–123.

Leopold, A., 1949. A Sand County Almanac, and Sketches Hereand There. Oxford Univ. Press, New York.

Lippke, B., Oliver, C.D., 1994. An economic tradeoff system forecosystem management. In: Jensen, M.E., Bouregeron, P.F.Ž .Tech. Eds. , Vol. II, Ecosystem Management: Principles andApplications. General Technical Report PNW-GTR-318,USDA Forest Service, Pacific Northwest Research Station,Portland, OR, pp. 318–326.

MacArthur, R.H., Wilson, E.O., 1967. The Theory of IslandBiogeography. Princeton Univ. Press, Princeton, NJ.

Margules, C., Usher, M.B., 1981. Criteria used in assessing

wildlife conservation potential: a review. Biol. Conservation21, 79–109.

May, R.M., 1994. The effects of spatial scale on ecologicalquestions and answers. In: Edwards, P.J., May, R.M., Webb,

Ž .N.R. Eds. , Large-scale Ecology and Conservation Biology.Blackwell, Oxford, UK, pp. 1–17.

McVicker, G., 1996. Presentation in Boulder, Colorado to Col-orado Rockies Regional Cooperative.

Meffe, G.K., Carroll, C.R., Contributors, 1994. Principles ofConservation Biology. Sinauer Associates, Sunderland, MA.

Morrissey, W.A., Zinn, J.A., Corn, M.L., 1994. Ecosystem man-agement: federal agency activities. CRS Report for Congress,94-399, ENR, Congressional Research Service and The Li-brary of Congress, Washington, DC.

Murkowski, F.H., 1995. Comments submitted to conference onChallenging Federal Ownership and Management: PublicLands and Public Benefits. Natural Resources Law Center,Univ. of Colorado School of Law, Univ. of Colorado, Boul-der, CO.

Newmark, W.D., 1985. Legal and biotic boundaries of westernNorth American parks: a problem of congruence. Biol. Con-servation 33, 197–208.

Newmark, W.D., 1987. Mammalian extinctions in western NorthAmerican parks: a land-bridge island perspective. Nature 325,430–432.

Newmark, W.D., 1995. Extinction of mammalian populations inwestern North American parks. Conserv. Biol. 9, 512–526.

Ž .Norton, T. Guest Ed. , 1995. Applications of population viabilityŽanalysis to biodiversity conservation. Biol. Conservation, 73 a

.special issue .Noss, R.F., 1983. A regional landscape approach to maintain

biodiversity. BioScience 33, 700–706.Noss, R.F., 1990b. What can wilderness do for biodiversity? In:

Ž .Reed, P. Ed. , Preparing to Manage Wilderness in the 21stCentury. General Technical Report SE-66, USDA Forest Ser-vice, Southeastern Forest Experiment Station, Asheville, NC,

Ž .pp. 49–61 cited in Noss and Cooperrider, 1994 .Noss, R.F., 1991a. Protecting habitats and biological diversity.

Part I: Guidelines for regional reserve systems. NationalŽ .Audubon Soc. New York cited in Noss, 1992 .

Noss, R.F., 1991b. Landscape conservation priorities in the GreaterYellowstone Ecosystem. Report to The Nature Conservancy,

Ž .Arlington, VA and Boulder, CO cited in Noss, 1992 .Noss, R.F., 1992. The wildlands project—land conservation strat-

egy. Wild Earth, special issue on The Wildlands Project—Plotting a North American Wilderness Recovery Strategy, pp.10–25.

Noss, R.F., 1994. Some principles of conservation biology, asthey apply to environmental law. Chicago-Kent Law Rev. 69,893–909.

Noss, R.F., Cooperrider, A.Y., 1994. Saving Nature’s Legacy—Protecting and Restoring Biodiversity. Island Press, Washing-ton, DC.

Noss, R.F., Harris, L.D., 1986. Nodes, networks, and MUMs:preserving diversity at all scales. Environ. Manage. 10, 299–309.

Noss, R.F., La Roe, E.T., III, Scott, J.M., 1995. Endangered


ecosystems of the United States: a preliminary assessment ofloss and degredation. Biological Report No. 28, Natl. Biol.Service, Washington, DC.

Oliver, C.D., 1992. A landscape approach: achieving and main-taining biodiversity and economic productivity. J. Forestry 90,20–25, Cited in Lippke and Oliver, 1994.

Overbay, J.C., 1992. Ecosystem management. In: Taking an Eco-logical Approach to Management. USDA Forest ServiceWorkshop, Salt Lake City, UT, pp. 3–15.

Patten, D.T., 1991. Human impacts in the Greater YellowstoneEcosystem: evaluating sustainability goals and eco-develop-ment. Conserv. Biol. 5, 405–411.

Pickett, S.T.A., Parker, V.T., Fiedler, P.L., 1992. The newparadigm in ecology: implications for conservation biology

Ž .above the species level. In: Fiedler, P.L., Jain S.K. Eds. ,Conservation Biology—The Theory and Practice of NatureConservation, Preservation and Management. Chapman & Hall,New York, pp. 65–88.

Primack, R.B., 1993. Essentials of Conservation Biology. SinauerAssociates, Sunderland, MA.

Rapport, D.J., 1989. What constitutes ecosystem health?. Perspect.Biol. Med. 33, 120–132.

Rasker, R., 1994. A new look at old vistas: the economic role ofenvironmental quality in western public lands. Univ. of Col-orado Law Review 65, 369–399.

Rauber, P., 1995. Improving on nature. Sierra 80, pp. 43–44,46–52, 70, 72.

Regier, H.A., 1993. The notion of natural and cultural integrity.Ž .In: Woodley, S., Kay, J., Francis, G. Eds. , Ecological In-

tegrity and the Management of Ecosystems. St. Lucie Press,Delray Beach, FL, pp. 3–18.

Roush, J., 1995. Freedom and responsibility: what we can learnfrom the Wise Use Movement. In: Echeverria, J., Eby, R.B.Ž .Eds. , Let the People Judge—Wise Use and the PrivateProperty Rights Movement. Island Press, Washington, DC, pp.1–10.

Rundel, P.W., 1995. The role of species in ecosystems. Conserv.Biol. 9, 467–469.

Sagoff, M., 1995. Carrying capacity and ecological economics.BioScience 45, 610–620.

Salwasser, H., 1994. Ecosystem management—can it sustain di-versity and productivity? J. Forestry 92, 6–7, 9–10.

Salwasser, H., Schonewald-Cox, C.M., Baker, R., 1987. The roleof interagency cooperation in managing for viable populations.

Ž .In: Soule, M.E. Ed. , Viable Populations for Conservation.´Cambridge Univ. Press, Cambridge, UK, pp. 159–173.

Schemske, D.W., Husband, B.C., Ruckelshaus, M.H., Goodwillie,C., Parker, I.M., Bishop, J.G., 1994. Evaluating approaches tothe conservation of rare and endangered plants. Ecology 75,584–606.

Schonewald-Cox, C.M., 1983. Conclusions: guidelines to manage-ment: a beginning attempt. In: Schonewald-Cox, C.M., Cham-

Ž .bers, S.M., MacBryde, B., Thomas, L. Eds. , Genetics andConservation—A Reference for Managing Wild Animal andPlant Populations. BenjaminrCummings, Menlo Park, CA,pp. 414–445.

Schonewald-Cox, C.M., Buechner, M., 1991. Housing viable pop-ulations in protected habitats: the value of a coarse-grainedgeographic analysis of density patterns and available habitat.

Ž .In: Seitz, A., Loeschcke, V. Eds. , Species Conservation: APopulation–Biological Approach. Birkshauser Verlag, Basel,¨Switzerland, pp. 213–226.

Schonewald-Cox, C.M., Buechner, M., 1992. Park protection andŽ .public roads. In: Fiedler, P.L., Jain, S.K. Eds. , Conservation

Biology: The Theory and Practice of Nature Conservation,Preservation and Management. Chapman & Hall, New York,pp. 373–395.

Schonewald-Cox, C.M., Azari, R., Blume, S., 1991. Scale, vari-able density, and conservation planning for mammalian carni-vores. Conserv. Biol. 5, 491–495.

Ž .Schulze, E., Mooney, H.A. Eds. , 1993. Biodiversity and Ecosys-tem Function. Springer, New York.

Schwartz, M.W., 1994. Natural distribution and abundance offorest species and communities in northern Florida. Ecology75, 687–705.

Scott, J.M., Davis, F., Csuti, B., Noss, R., Butterfield, B., Groves,C., Anderson, J., Caicco, S., D’Erchia, F., Edwards, T.C. Jr.,Ulliman, J., Wright, R.C., 1993. Gap analysis: a geographicapproach to protection of biological diversity. Wildlife Mono-graphs 123, 1–41.

Seastedt, T., 1994. Ecosystem management: the new tool of landmanagers? Document prepared for Open Space Department,City of Boulder, CO.

Serafin, R., Steedman, R., 1991. Working group report: measuringintegrity at the municipal level. In: Workshop on EcologicalIntegrity and the Management of Ecosystems. Heritage Re-source Center, Univ. of Waterloo, Waterloo, ON, CanadaŽ .cited in Pell, 1995 .

Shepard, W.B., 1994. Ecosystem management in the Forest Ser-vice: political implications, impediments, and imperatives. In:

Ž .Jensen, M.E., Bourgeron, P.F. Technical Ed. , EcosystemManagement: Principles and Applications, Vol. II. GeneralTechnical Report PNW-GTR-318, USDA Forest Service, Pa-cific Northwest Res. Station, Portland, OR, pp. 27–33.

Sinclair, A.R.E., Hik, D.S., Schmitz, O.J., Scudder, G.G.E.,Turpin, D.H., Larter, N.C., 1995. Biodiversity and the need forhabitat renewal. Ecol. Applications 5, 579–587.

Smith, F., May, R., Pellew, R., Johnson, T., Walter, K., 1993.How much do we know about current extinction rate?. TrendsEcol. Evolution 8, 375–378.

Soule, M.E., 1980. Thresholds for survival: maintaining fitness´and evolutionary potential. In: Soule, M.E., Wilcox, B.A.´Ž .Eds. , Conservation Biology—An Evolutionary-EcologicalPerspective. Sinauer Associates, Sunderland, MA, pp. 151–169.

Soule, M.E., 1985. What is conservation biology?. BioScience 35,´727–734.

Stanley, T.R. Jr., 1995. Ecosystem management and the arroganceof humanism. Conserv. Biol. 9, 255–262.

Steen, H.K., 1976. The US Forest Service: A History. Univ. ofŽWashington Press, Seattle, WA cited in Kennedy and Quigley,

.1994 .


Swanson, F.J., Franklin, J.F., 1992. New Forestry principles fromecosystem analysis of Pacific Northwest Forests. Ecol. Appli-cations 2, 262–274.

Swanson, F.J., Jones, J.A., Wallin, D.O., Cissel, J.H., 1994.Natural variability—implications for ecosystem management.

Ž .In: Jensen, M.E., Bourgeron, P.S. Tech. Eds. , Vol. II,Ecosystem Management: Principles and Applications. GeneralTechnical Report PNW-GTR-318, USDA Forest Service, Pa-cific Northwest Forest Research Station, Portland, OR, pp.80–94.

The Keystone Center, 1991. Final consensus report of the Key-stone Policy Dialogue on Biological Diversity on FederalLands. The Keystone Center, Keystone, CO.

The Keystone Center, 1993. National Ecosystem ManagementForum meeting summary. Keystone, CO.

The Keystone Center, 1995. Keystone National Policy Dialogueon Ecosystem Management—Southwest, Northeast, andNorthwest Regional Meetings, and Second Plenary Session.The Keystone Center, Keystone, CO.

The Nature Conservancy, 1991. Last great places—the NatureConservancy’s protection initiative for the 1990s. Nature Con-

Ž .servancy, MayrJune 1991 a special issue .Thomas, J.W., 1994. Concerning ‘‘New Directions in the Forest

Service’’. Testimony before the Committee on Natural Re-sources, US House of Representatives, Washington, DC.

USDA Forest Service, 1991. Charter for new perspectives forŽmanaging the National Forest System. Washington, DC cited

.in Kessler and Salwasser, 1995 .USDA Forest Service, 1994a. The Forest Service ethics and

course to the future. USDA Forest Service, FS 567, Washing-ton, DC.

USDA Forest Service, 1994b. A national framework—ecosystemmanagement. Washington, DC.

USDA Forest Service, 1994c. Western forest health initiative.

State and Private Forestry, USDA Forest Service, Washington,DC.

US Man and the Biosphere Program, 1994. Strategic plan for theUS Biosphere Program. Biosphere Reserve Directorate, USMan and the Biosphere Program, Dept. of State Publication10186, Washington, DC. Available as No. NTIS PB95-101226-1994 from National Technical Information Service,Springfield, VA.

Walters, C.J., Holling, C.S., 1990. Large-scale management exper-iments and learning by doing. Ecology 71, 2060–2068.

Westman, W.E., 1990. Park management of exotic plant species:problems and issues. Conserv. Biol. 4, 251–260.

Wilcove, D.S., 1994. Turning conservation goals into tangibleresults: the case of the spotted owl and old-growth forests. In:

Ž .Edwards, P.J., May, R.M., Webb, N.R. Eds. , Large-scaleEcology and Conservation Biology. Blackwell, Oxford, UK,pp. 313–329.

Wilcove, D.S., Blair, R.B., 1995. The ecosystem managementbandwagon. Trends Ecol. Evolution 10, 345.

Wilcove, D.S., McMillan, M., Winston, K.C., 1993. What exactlyis an endangered species? An analysis of the US endangeredspecies list: 1985–1991. Conserv. Biol. 7, 87–93.

Wilcox, B.A., 1980. Insular ecology and conservation. In: Soule,´Ž .M.E., Wilcox, B.A. Eds. , Conservation Biology—An Evolu-

tionary-Ecological Perspective. Sinauer Associates, Sunder-land, MA, pp. 95–117.

Woodwell, G.M., 1990. The earth under stress: a transition toclimatic instability raises questions about patterns of impover-

Ž .ishment. In: Woodwell, G.M. Ed. , The Earth inTransition—Patterns and Processes of Biotic Impoverishment.Cambridge Univ. Press, Cambridge, UK, pp. 3–7.

Yaffee, S.L., 1994. The Wisdom of the Spotted Owl—PolicyLessons for a New Century. Island Press, Washington, DC.

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