Landscape Ecology and Nature Reserve Design in the Boundary Waters Canoe Area, Minnesota

Temporal change in the biosphere occurs at different rates and in different ways, depending on spatial scale. One hypothesis is that in environments where disturbances produce patches and temporal instability in small areas, the aggregate mosaic of these patches on larger areas may be constant, so that a "shifting—mosaic steady state" occurs. If so, then the appropriate minimum size for a nature reserve might be the minimum land area on which the patch—mosaic is stable. To test for a stable patch—mosaic I subdivided the Boundary Waters Canoe Area (BWCA) into smaller units at five spatial scales and used the fire history data published by Heinselman to reconstruct temporal changes in the patch—mosaic on each unit. A temporally stable patch—mosaic was not evident at any scale, largely due to (1) spatial heterogeneity in the fire—regime and/or environment, and (2) a mismatch between the grain of fire—patches and the grain of the environment. The pattern of temporal instability present on the BWCA as a whole was not replicated on smaller areas. Nature reserve design and management practices that focus on the landscape level, community level, or species level may conflict. If the management goal is to perpetuate natural fluctuations in landscape structure, then certain species dependent on landscape structure may fluctuate as well. Maintaining stable populations of these species may entail landscape manipulations that lower the value of the reserve for perpetuating landscape processes and structures.