Impacts of habitat fragmentation and patch size upon migration rates

A spatially explicit model (MIGRATE) was used to investigate the effects of habitat loss and fragmentation on the ability of species to migrate in res ponse to climate change. Illustrative simulations were run using parameters that represent the reproductive and dispersal characteristics of the: wind -dispersed tree Tilia cordata (small-leaved lime). Hierarchically structure d landscapes with different patch sizes and overall habitat suitability lev els were generated at a 1-km resolution for a 200 x 800 km area. Simulated migration rates slowed markedly when habitat availability fell below simila r to 25% of the landscape area, especially in landscapes composed of fewer larger patches. The implication of these results for the management of land scapes for species conservation is discussed.