Targeting sites for conservation: Using a patch-based ranking scheme to assess conservation potential

Rare habitats are increasingly threatened by fragmentation and measures are required to conserve these valuable resources. Here, we present a method o f targeting habitat patches for conservation using a Geographical Informati on System. We ranked patches of chalk grassland in the Chiltern Hills Area of Outstanding Natural Beauty using simple abiotic criteria, namely: patch area, patch shape, proximity to areas of the same habitat and surrounding l and-use type. We compiled a regionally specific list of indicator species a nd ranked the habitat patches based on their alpha diversity (calculated fr om species richness). We compared the results of the two ranking schemes an d identified key aggregations of the existing reserve network. These could form the basis of future habitat expansion as required by the United Kingdo m Biodiversity Action Plan. (C) 2001 Academic Press.