INTERACTIONS BETWEEN THE FRACTAL GEOMETRY OF LANDSCAPES AND ALLOMETRIC HERBIVORY

The scale at which herbivorous mammals forage is determined in part by home range area, population density, metabolic rate, movement speed, transport costs, and ingestion rate. These ecological, behavioral, and physiological characteristics that vary with body mass constitute the notion of allometric herbivory. In fractal landscapes, forage density varies with the scale at which animals perceive the resource. Interactions between scale-dependent resource density and allometric herbivory were investigated by using remotely sensed imagery to simulate fragmented distributions of forage biomass in an 810-ha landscape, and then simulating allometric herbivory for 2-6-kg animals. Between years, changes in landscape geometry altered foraging success. Within years, resource depletion resulted in increased aggregation among foragers followed by sudden increases in mobility and dispersion. Portions of the forage remained after the foragers shifted from the aggregation phase to one of mass dispersal. Spatial patterns of resources may regulate resource uptake and depletion rates within the landscape, with potential implications for demographics, intra-specific competition, and community assembly. © 1992.