Conservation of Biodiversity in a World of Use.

Over the last decade biodiversity conservation has become an objective of international conventions, national governments, state agencies, non-governmental organizations, local communities, school clubs, and individuals. Unfortunately, while becoming a common objective, the true meaning of biodiversity conservation has been pulled from its roots in the biological sciences, becoming a political concept with as many meanings as it has advocates. This confusion of meanings can frustrate efforts to mobilize conservation action, because successful conservation relies on clear goals laid out with specific and commonly understood definitions and assumptions.

Of the many confusing concepts associated with biodiversity conservation, few demand greater definition and scrutiny than "conservation through use," sometimes known as "compatible" or "sustainable" use. At face value these terms suggest that certain types or levels of human use are ecologically benign, incurring little or no loss of biodiversity. In fact, it was the promise that such human use would serve as the basis for conservation that brought so many different interest groups to agree on the importance of biodiversity conservation. Advocates of compatible use have suggested that substituting a compatible use for an incompatible one, or helping to perpetuate an existing use deemed as being compatible, is a reasonable strategy for conserving biodiversity. But strong warnings have been issued by conservation biologists such as Freese (1998): "Human intervention in an ecosystem for commercial purposes inevitably alters and generally simplifies, at some scale, ecosystem structure, composition, and function."

We maintain that compatibility between human use and biodiversity conservation cannot be stated in binary terms as a "yes" or "no" condition. All use has consequences. Different kinds and intensities of human use affect various aspects or components of biodiversity to differing degrees. Further, individual or societal decisions about the degree of biodiversity impact that is deemed "compatible" are value dependent and should be recognized as such. In reality, the incidence, the source, and the effects of many changes are often unclear, and that lack of clarity impedes action on both political and practical levels.

Because the interaction between biodiversity and human use results in such complex impacts and variable degrees of conservation, we believe that some means of measuring the success of biodiversity conservation efforts is desperately needed. In that spirit, we have proposed a heuristic framework for measuring the consequences of human use for biodiversity. This framework builds from a matrix presented by Noss (1990) and draws from a very specific definition of biodiversity.

Biodiversity refers to the natural variety and variability among living organisms, the ecological complexes in which they naturally occur, and the ways in which they interact with each other and with the physical environment. Biodiversity has three different components: genetic, population/ species, and community/ecosystem. Each of these components has compositional, structural, and functional attributes. Composition refers to the identity and variety of elements in each of the biodiversity components. Structure refers to the physical organization or pattern of the elements. Function refers to ecological or evolutionary processes acting among the elements.

We suggest that the effects of human use or alteration on biodiversity can be assessed with our framework by determining how different types and intensities of resource use affect both the components of biodiversity and their attributes as defined above. In order to test the application of the framework, we examined conservation efforts at two sites where The Nature Conservancy has been working: the Roanoke River in North Carolina and the Pantanal in Brazil. We then additionally tested the framework against illustrative examples of human resource use from the literature.

The results of our assessments demonstrate that the full range and expression of biodiversity components and attributes can be conserved only in ecological systems that are altered either very little or not at all. In those systems in which human impacts are more pronounced, the different biodiversity components and attributes are often affected. Some of these components and attributes are more sensitive to human use, while others are more robust. For example, genetic effects appear under much lighter regimes of use than do changes in ecosystem function.

Figure 1. Effects of resource use systems on the components and
attributes of biodiversity. Reproduced from Redford and Richter 2000.

BIODIVERSITY COMPONENT AND ATTRIBUTE

                                     TYPES OF USE

                 Irrigation    Hydropower    Intensive      Grazing in
                   Supply       Dams(2)        Coral       Historically
                Resevoirs(1)                   Reef          Ungrazed
                                            Fishing(3)      Forests(4)

COMMUNITY /
 ECOSYSTEM

function            ()            A             A              A
structure           ()            A             A              A
composition         ()            A             A              A

POPULATION /
 SPECIES

function            ()            ()            ()             A
structure           ()            ()            ()             A
composition         ()            ()            ()             A

GENETIC

function            ()            ()            ()             A
structure           ()            ()            ()             A
composition         ()            ()            ()             A

                              TYPES OF USE

                  Water       Harvesting    Wilderness
               Diversion(5)    Nontimber      River
                               Forests      Running(7)
                              Products(6)

COMMUNITY /
 ECOSYSTEM

function            B             B             B
structure           B             B             B
composition         A             B             B

POPULATION /
 SPECIES

function            A             A             B
structure           A             A             B
composition         A             A             B

GENETIC

function            A             A             B
structure           A             A             B
composition         A             A             B

() not conserved

A partially conserved

B completely conserved

(1) Western North America: Rood & Mahoney 1990; Poff et al. 1997.

(2) Global: Cushman 1985; Moog 1993.

(3) Global: Roberts 1995; Laikre & Ryman 1996.

(4) Western U.S.: Belsky & Blumenthal 1997.

(5) California, U.S.: Harris et al. 1987; Stromberg & Patten 1992.

(6) Tropical forests: O'Brien & Kinnaird 1996; Peters 1996.

(7) Global: Tejada-Flores 1978; B.D. Richters, personal obervation.

We found that all consumptive use affects biodiversity in some attribute or component, commonly affecting not only the target component but other components as well. For example, the genetic component has been shown to be adversely affected by harvesting, be it fishing, logging, or trophy hunting. The population/species component is most commonly understood to be affected by human uses, and much work has demonstrated this, although subtle effects are often missed. Of increasing importance is an understanding of how the community/ecosystem component has been and is being affected by human activities. The extent to which the different attributes are affected by use remains a little understood and important topic for further research.

The primary points we gained from our analyses are that:

* different degrees of human use or alteration result in different negative effects on biodiversity;

* some components and attributes of biodiversity are more sensitive than other components to human use or alteration; and

* only extremely limited use or virtually no alteration will protect all components.

In our daily work we confront the discordance between the view that humans can use biodiversity without causing any harm, and our experience, shared by many of our peers, that this is not possible.

We follow in a long history of those who advocate that all biological entities and their environments have intrinsic value independent of their usefulness to humans. This value applies not just to species, or communities, or ecosystems, but to the complex intertwined web of life that has come to be called biodiversity. In such a value system, the preservation of biodiversity for its own sake, in its entirety and in its component parts, is a legitimate objective in and of itself. Our analysis suggested that biodiversity in its entirety can be conserved only in areas of very limited or no human use. But the vast majority of both the terrestrial and aquatic world have been, and will continue to be, vital sources of resources for the human population. We live in a world of use. But we must accept the undeniable fact that we cannot fully conserve the biodiversity of this planet through compatible or sustainable resource use strategies alone. All comprehensive biodiversity conservation strategies must be rooted in large protected areas in both the terrestrial and the marine realm.

The literature we sampled for our analysis is part of an ever-growing body of evidence that pinpoints the effects of specific human uses on specific components of biodiversity. By incorporating this evidence into an analytical framework, conservation biologists can work to provide critical a priori assessments of the biodiversity costs of resource use. Such an approach would also support working with resource harvesters to improve the effectiveness of their harvesting methods to ensure that those components and attributes that can be conserved under their use regimes are conserved. This should help to achieve a key goal of moving resource production systems towards more ecologically benign practices.

It is time for conservation biologists to overcome their methodological differences and the limitations of their data and unite to provide answers and approaches to one of the major issues confronting humans and the other inhabitants of our world--how to sustain the full diversity of life in a world of use.

Literature cited

Freese, C. 1998. Wild Species as Commodities. Washington, DC: Island Press.

Noss, R. 1990. Indicators for monitoring biodiversity: A hierarchical approach. Conservation Biology 4: 355-364.

Kent H. Redford International Program of the Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, NY 10460; [e-mail]

Brian Richter The Nature Conservancy, 490 Westfield Rd., Charlottesville, VA 22901; [e-mail]