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Yellowstone National Park Report

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This study is an investigation of long-term patch dynamics in the mosaic of forest communities covering the subalpine plateaus of Yellowstone Park. Our specific objectives are the following: (1) We will map the present forest mosaic of a 600,000-ha area, showing the age (number of years since the last destructive fire) and successional stage of each more-or-less homogeneous patch of forest. (2) Using this map, we will measure the area of each patch created by past fires, determine the size distribution of patches, and estimate the frequency and predictability of formation of patches of each size. (3) We will reconstruct the changes during the last 200-300 years in individual forest stands and in the entire landscape mosaic, and use these reconstructions to answer the following questions: (a) Has the Yellowstone landscape been characterized by quasi-equilibrium conditions, in which the proportion of the total area covered by early, middle, and late successional stages and the diversity of plant communities represented have remained more-or-less constant, or have these parameters fluctuated greatly in the last 250 years? (b) If we find that the entire landscape has been in a state of equilibrium (which we may not find), then what is the minimum land area necessary for landscape dynamics to approach this condition, i.e., to what extent could the Park be divided into isolated subunits without these subunits losing the quasi-equilibrium state? (c) How have the proportions of forest successional stages varied over time in units of the Park that have special ecological interest, such as elk summer range, grizzly bear habitat, or the watershed of Yellowstone Lake?