Ecological Issues in Conservation¹

Conservation biology, which can be defined as science in the service of conservation, emerged as a distinct discipline in the late 1970s when a critical mass of scientists became concerned about the global extinction crisis.Conservation biology is fundamentally a union of population genetics, systematics, and ecology, often with strong input from land-use planning, natural resources management, public policy, philosophy, and other fields.Like other applied sciences, such as medicine and engineering, conservation biology relies on the data and theories of basic researchers.In return, conservation biology offers new, interdisciplinary insights and approaches to such questions as the relation of species to habitat at multiple spatial and temporal scales, the processes that generate and maintain biodiversity, the structure of food webs, population persistence in variable environments, and the multifarious effects of human activities on ecosystems.For all these problems, conservation biology seeks real-world solutions.In this Invited Feature we explore the intersection of conservation biology and ecology, asking how an understanding of ecological patterns and processes might inform conservation practice.The papers in this series, with the exception of that by DeVelice and Martin, were presented in a symposium at the annual meeting of the Ecological Society of America (ESA) in Spokane, Washington, 10 August 1999.The original symposium title, ''Ecological issues in large-scale conservation,'' applies to most of the papers in this series reasonably well.Upon close examination, however, it is apparent that some of these papers address questions across a range of scales, not necessarily large.Integrating lessons learned across a spectrum of spatial and temporal scales is likely to prove useful to conservation efforts.The paper by Berger and coauthors is the sole contribution to this series based on a field experiment.As such, it involves the smallest geographical area (the southern Greater Yellowstone ecosystem), yet it confronts a topic that has implications for the integrity of ecosystems across North America and beyond-the community-level effects of the loss of top predators.Through a replicated natural experiment comparing matched sites with and without human hunting, but all missing their native large carnivores, grizzly bears (Ursus arctos) and wolves (Canis lupus), Berger et al. document an irruption of moose in the absence of predation, severe impacts of moose herbivory on the structure and density of riparian vegetation, and corresponding declines in songbird richness and density.Their findings lend support to the hypothesis of top-down regulation of community structure and suggest management options for areas currently lacking large predators.The optimal approach, where possible, is reintroduction of natural predators, but in some cases human hunting must substitute for natural predation.Carroll et al. also address mammalian carnivores, but their study region extends northward from the Greater Yellowstone ecosystem to encompass 450 000 km 2 of the Rocky Mountains of the United States and Canada.This study evaluated the utility of four species of carnivores as focal species for conservation planning: fisher (Martes pennanti), lynx (Lynx canadensis), wolverine (Gulo gulo), and grizzly bear.Carroll et al. developed habitat suitability models for these species on a regional scale, then tested these models with independent data sets.The results challenge the notion that a single, presumed ''umbrella'' species, such as the grizzly bear, can be used to protect habitat for most other species.Predicted habitat for the bear overlaps substantially with that for wolverine, but only moderately with fisher and poorly with lynx.These results lend support to multispecies conservation planning.Moreover, the maps generated by the models indicate areas of high conservation value, potential habitat linkages, and areas where critical habitat is rapidly being lost to human development.In the third paper in this Invited Feature, Catherine Pringle explores the importance of hydrologic connectivity in the management of biological reserves.Most reserves have been set aside for terrestrial biota and have all but ignored aquatic biodiversity.Consequently, and as a result -REED F.

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