Peter B. Landres

OVERVIEW OF THE USE OF NATURAL VARIABILITY CONCEPTS IN MANAGING ECOLOGICAL SYSTEMS

Natural resource managers have used natural variability concepts since the early 1960s and are increasingly relying on these concepts to maintain biological diversity, to restore ecosystems that have been severely altered, and as benchmarks for assessing anthropogenic change. Management use of natural variability relies on two concepts: that past conditions and processes provide context and guidance for managing ecological systems today, and that disturbance-driven spatial and temporal variability is a vital attribute of nearly all ecological systems. We review the use of these concepts for managing ecological systems and landscapes. We conclude that natural variability concepts provide a framework for improved un- derstanding of ecological systems and the changes occurring in these systems, as well as for evaluating the consequences of proposed management actions. Understanding the history of ecological systems (their past composition and structure, their spatial and temporal variability, and the principal processes that influenced them) helps managers set goals that are more likely to maintain and protect ecological systems and meet the social values desired for an area. Until we significantly improve our understanding of ecological systems, this knowledge of past ecosystem functioning is also one of the best means for predicting impacts to ecological systems today. These concepts can also be misused. No a priori time period or spatial extent should be used in defining natural variability. Specific goals, site-specific field data, inferences derived from data collected elsewhere, simulation models, and explicitly stated value judg- ment all must drive selection of the relevant time period and spatial extent used in defining natural variability. Natural variability concepts offer an opportunity and a challenge for ecologists to provide relevant information and to collaborate with managers to improve the management of ecological systems.

Threats to Wilderness Ecosystems: Impacts and Research Needs

One of the primary purposes of designated wilderness areas is protection of natural ecosystems. However, the ecological integrity of these most protected of public lands is threatened by direct and indirect effects of human activities both internal and external to wilderness. Accelerated research programs on threats to wilderness are needed to realize the purposes for which wilderness was established and to improve our understanding of natural ecosystems. This paper reviews current knowledge and critical research needs for some of the most significant threats to wilderness ecosystems: (1) recreational use and its management; (2) livestock grazing and its management; (3) fire management; (4) introduction of alien species; (5) diversion and impoundment of water; (6) emission of atmospheric pollutants; and (7) management of adjacent lands. Some of these threats cause highly disruptive localized impacts, whereas some have a more widespread effect. Other threats are highly significant because they threaten rare or irreplaceable ecological attributes. Ecological science needs to be applied to improve evaluations of wilderness conditions, improve efforts to protect wilderness ecosystems from further degradation, and improve efforts to restore the integrity of disturbed systems.

Guiding concepts for park and wilderness stewardship in an era of global environmental change.

The major challenge to stewardship of protected areas is to decide where, when, and how to intervene in physical and biological processes, to conserve what we value in these places. To make such decisions, planners and managers must articulate more clearly the purposes of parks, what is valued, and what needs to be sustained. A key aim for conservation today is the maintenance and restoration of biodiversity, but a broader range of values are also likely to be considered important, including ecological integrity, resilience, historical fidelity (ie the ecosystem appears and functions much as it did in the past), and autonomy of nature. Until recently, the concept of “naturalness” was the guiding principle when making conservation-related decisions in park and wilderness ecosystems. However, this concept is multifaceted and often means different things to different people, including notions of historical fidelity and autonomy from human influence. Achieving the goal of nature conservation intended for such...

The Wilderness act and fish stocking : An overview of legislation, judicial interpretation, and agency implementation

Many high-elevation lakes in designated wilderness are stocked with native and nonnative fish by state fish and game agencies to provide recreational fishing opportunities. In several areas, this practice has become controversial with state wildlife managers who support historical recreational use of wilderness, federal wilderness managers who assert that stocking compromises some of the ecological and social values of wilderness, and different public groups that support one or the other position. Herein we examine this controversy from the perspective of the 1964 Wilderness Act, its judicial interpretation, the policies of the federal agencies, and formal agreements between federal and state agencies. Although some state stocking programs restore native fish populations, other programs may compromise some of the ecological and social values of wilderness areas. Further, although current federal regulations recognize state authority for fish stocking, judicial interpretation gives federal agencies the authority for direct involvement in decisions regarding fish stocking in wilderness. Where there are differences of opinion between state and federal managers, this judicial interpretation strongly points to the need for improved cooperation, communication, and coordination between state wildlife managers and federal wilderness managers to balance recreational fishing opportunities and other wildlife management activities with wilderness values.