Spatial Aggregation and Neutral Models in Fractal Landscapes

Fragmented landscapes alter ecological interactions by modifying the flux of organisms, material, and energy. Fragmented distributions of hypothetical resources and species were represented by several fractal models of landscape patterns at scales ranging from 90 to 2,400 m. Maps of resource aggregations at three scales resulted in multiple-scale notions of "patch," "gap," "edge," "corridor," "source," and "sink." A neutral model of species co-occurrence was developed for analyses conducted at several scales. The neutral model has implications for sampling mutualistic species and for detecting species' responses to changes in environmental conditions. An ecologically meaningful view of landscape pattern depends on the home range size, dispersal ability, or speed with which organisms use resources rather than on the cartographic depiction of the landscape used by humans.