Ecological implications of landscape fragmentation

The effects of scale-dependent changes in habitat patterns were investigated by simulating two consumer populations on random and hierarchically random landscapes. The first consumer depleted resources as it randomly walked across the landscape, while the second consumer spread outwards to suitable sites from an initial point. Simple random landscapes were generated by randomly selecting the habitat suitability of each site, while hierarchically random maps were generated by a nested series of rules which changed the probabilities with spatial scale. These two map types were compared to digitized land-use data. Three effects were observed: (1) the reduction of available habitat always reduced population abundance and spread, (2) small changes in landscape pattern produced sudden changes in abundance which could be predicted from the interaction between landscape characteristics and population specific life history parameters, and (3) the hierarchically structured landscapes affected abundances most when habitat fragmentation coincided with the scales at which the consumer populations utilized spatial resources.