Shifting Environmental Foundations: The Unprecedented and Unpredictable Future

NATHAN L. STEPHENSON, CONSTANCE 1. MILLAR, AND DAVID N. COLE ex:panding human impacts suggest that hUlllan intervention in ecosystems may be essential to protect critical values in parks and wilderness areas. Ecological restoration has moved toward the forefront of stewardship policY and practice. As a case in point, National Park Service (2006: 37) management policies call for the restoration of naturally functioning ecosystems and, if this is not possible, for the restoration and maintenance of"the dosest approximation of the naurral condition;' Although restoration Illay enhance some of the values of naturalness, such as maintenance of native biodiversity, widespread intervention erodes other meanings and values of naturalness-natural areas as places where humans do not willfully manipulate ecosystems, where nature remains self-willed and autonomous. vVhere intervention and restoration are needed and feasible, protected area managers must develop realistic objectives and devise effective strategies for achieving them. In part because of the centrality of historical fidelity to notions of naturalness, past ecosystem conditions have conunonly been adopted as targets for the future. With recognition of the inherent dynamism of ecosystems (Chapter 3), reference targets for restoration are often prescribed as a range of past conditions, often called natural or historical range of variability (Landres et al. 1999), rather than conditions at a single point in time. But given the r\lpid pace/of directional anthropogenic changes, such targets, even those expressed as a range, lllay be neither achievable nor desirable. Although dle range of past ecosystem conditions rerllains a valuable source ofinformation about the forces that shape ecosystems (Swetnam et al. 1999), it no longer autOlnatically serves as a sensible target for restoration and maintenance ofecosystems. Our world has entered an era in which keystone environmental drivers-those that define the possible range of characteristics of a protected area-simply have no analog in the past, no matter how distandy we look. Attempts to restore and rnaintain a semblance ofpast conditions therefore Inay be akin to forcing square pegs into round holes. Furthermore, at the spatial and temporal scales relevant to protected area management, dle ability to predict future ecosystem conditions and outcomes ofmanagement actions is, at best, qualitative. Surprises are inevitable and are likely to be dle rule radler than the exception. In this chapter, we explore dle implications of rapid global changes for protected area stewardship. We describe the major classes ofanthropogenic drivers ofchanges in protected areas, including habitat fraglnentation, loss of top predators, pollution, invasive species, altered disturbance regilnes, and climatic change, concluding that resultant ecosystem changes are likely to be dramatic, ubiquitous, directional, and unprecedented. And even with , J' J, , r..