Ethical Issues in Biodiversity Protection Figure Healthy and unhealthy rangelands (a) A natural grassland with numerous native species on the National Bison Range, federally protected land in the state of Montana (b) Cattle graze on natural grassland (c) Overgrazed grassland takes on the appearance of a desert and native species are eliminated Photographs courtesy of the U.S Fish and Wildlife Service and the U.S Forest Service suppressed throughout the national parks; they were perceived as dangerous to both people and forests Over time, however, fire ecologists documented the historical role of fires in creating the natural landscape and preserving fire-dependent species of plants and animals In response, land managers have introduced controlled burning into parks and allowed some lightning-ignited fires to burn Improved ecological understanding and an attempt to distinguish between what is good for the ecosystem and what is comfortable or familiar for people have shown that wolves and fire belong in the parks The fact that ecosystems are not as strongly integrated, clearly bounded, or stable as individual organisms complicates attempts to specify ecological integrity in particular cases It is sometimes difficult to stipulate which outside influences represent assaults on integrity rather than mere changes Recent study suggests that many ecosystems are relatively loose assemblages of species; that these assemblages may be relatively recent and transient creations; and that even left to themselves many natural communities will not necessarily reach a 311 particular, invariant climax state but may instead reach any one of a number of more or less stable states, or no stable state whatsoever If species assemblages are always changing naturally, why distinguish species that are extirpated or introduced by humans, as when conservationists reintroduce wolves in the Rockies or eradicate wild boars in the Great Smoky Mountains? If there is no one natural end point to succession, why assume that human-created early-successional stages (fields of shrubs after clear-cuts) have less integrity than naturally occurring latesuccessional stages (old-growth forests)? Still, ecosystems typically go through characteristic successional stages and support characteristic (if not invariant or exact) species assemblages Though natural species assemblages change, this usually occurs on a time-scale that allows for much stability, the development of complex interactions between organisms, and the increase of biological diversity at the landscape level In contrast, human-induced changes typically decrease biodiversity and always lead to a landscape that is partly our creation This loss of independence arguably marks a qualitative change in an ecosystem0 s natural history and a corresponding loss of ecosystem integrity (Foreman, 2004) Applying this complex concept to particular ecosystems thus involves attention to scale, knowledge of an ecosystem0 s particular history, and comparison with the structures and functioning of similar ecosystems Maximizing ecological integrity involves balancing the sometimes conflicting goals of freedom from human interference and preservation of historical natural communities Despite these complications, the desire to restore degraded ecosystems demands robust conceptions of ecosystem integrity and health Ecologists attempting to restore ruined pasture-lands to native prairie in Wisconsin, worked-out strip mines to forests in Appalachia, or drained lands back to wetlands in Florida, must set specific objectives (Figure 2) As with land managers seeking to limit their effects on relatively pristine areas, restorationists have taken health and integrity, defined in relation to natural baselines, as goals for restored landscapes Sustainability ‘‘Live Sustainably!’’ has become a rallying cry in the environmental movement Like health and integrity, sustainability is a term that blends facts and values, helping us act on our environmental convictions At a minimum, sustainability involves preserving resources for future generations But this minimum will not satisfy conservation biologists, who insist that part of what must be sustained is the full complement of biological diversity, for its own sake and for the benefit of humans Wide differences exist here For instance, in 1987 the United Nations World Commission on Environment and Development (the Brundtland Commission) defined sustainable development as ‘‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs.’’ The focus here is wholly on human beings On this definition the mass extinction of species is sustainable, provided future generations of people can meet their self-defined needs Noss summarized the