LTREB: Moose Population Cycles, Ecosystem Properties, and Landscape Patterns on Isle Royale

9806313 Pastor The difficulties in developing a general theory of herbivore-ecosystem interactions arise from the long time-scales of population cycles, the complex spatial scaling of interactions between animal and plant populations, and thenon-linear effect of herbivores on carbon and nutrient flows between vegetation and soil. Such theoretical difficulties are compounded by the paucity of long-term, landscape-scale studies. This LTREB research will continue to address these problems by examining the spatial distribution of browse consumption by moose (Alces alces) in relation to browse supply, tree diameter distributions, conifer basal area, and soil nitrogen availability in the boreal forests of two valleys on Isle Royale. A series of alternative hypotheses will be tested: One series of hypotheses states that spatial patterns do not determine ecosystem recovery from the prior period of high moose population densities, while the alternative series of hypotheses invoke a central role of the dynamics of spatial patterns in ecosystem recovery. Changes in mean values of each ecosystem property will be tested by examining trends at grid points through time. This long-term research program covers a period of time in which the system has experienced the both the largest and smallest moose population densities. These extremes in population dynamics will provide valuable information on the effects of herbivores on large-scale plant community dynamics and ecosystem processes.