Developing regional and species-level assessments of climate change impacts on biodiversity in the Cape Floristic Region

We assess the potential impact of climate change on plant diversity in the Cape Floristic Region (CFR) and its interaction with land transformation that has already occurred in the region. Predictions were made both at the scale of the Fynbos Biome (the dominant vegetation assemblage in the CFR) and for selected Proteaceae species. Bioclimatic modelling identified parts of the biome at particular risk from climate change. Species-level modelling (Generalised Additive Modelling) was done for 28 Proteaceae species selected from areas at high risk of biome loss, revealing individualistic range changes in a pattern broadly consistent with biome modelling results. Most species experienced potential range contractions (17 of 28), of which five showed range elimination. Several species (I I of 28) showed potential range expansions. For species showing range contractions, current land transformation had less impact on future potential ranges than did climate change, because many species ranges shifted to higher altitudes where land transformation is currently less prevalent. Fewer than half of the high-risk species showed overlap between current and future potential range, showing that propagule transport, establishment of species in novel ranges and conservation of landscape linkages will be critical for maintenance of biodiversity. Methods described here provide useful forecasts of potential climate change impacts that could guide conservation responses, but results need cautious interpretation in the light of the many assumptions underlying the techniques used. (C) 2003 Elsevier Science Ltd. All rights reserved.