Modeling viable mammal populations in gap analyses

Gap analysis is an approach to conserving biological diversity that maps sp ecies richness and identifies sites that ought to be protected but are not in conservation networks. Cap analyses based on species richness may have h igh error rates when species models are based solely on species-habitat ass ociations, because patches too small to support populations are still consi dered to be potential habitat. We incorporated information on the home rang e and dispersal distances of the mammals of Florida to estimate minimum cri tical areas (MCA) to support minimum viable populations for each mammal spe cies. Incorporating MCA decreases the area occupied by the highest levels o f species richness, and alters the mapped spatial distribution of potential species richness. For example. in St. Lucic and Okeechobee counties, Flori da, the total area occupied by 15 or more species was 30,448 ha under simpl e mammal-habitat association models, but only 7820 ha under model condition s incorporating MCA. This reflects the fragmented condition of many landsca pes, where most patches are too small to support viable populations of larg er species. Incorporating minimum area requirements into maps of potential species richness produces more conservative and defensible maps. (C) 2001 E lsevier Science Ltd. All rights reserved.