Changing habitat areas and static reserves: challenges to species protection under climate change

Abstract

Context: When climate changes, species’ distributions may either shift spatially or expand/contract around continuously-occupied refugia, altering the effectiveness of previously-fixed conservation reserve networks. Objectives: We characterise the nature of climate-induced changes in species’ distributions and the extent of protected habitat, using a topographically diverse, subtropical case-study region. Methods: Bioclimatic species’ distribution models were developed for 13 representative forest-dependent species spanning four vertebrate classes. We used a fine-scale 0.25 km grid with nine environmental and eight climatic predictor variables, selected for biological and land-use realism and statistical independence. Downscaled climate data for future climate regimes were quantified from regional climate data together with the IPCC A1FI predictions for 2040 and 2090. Results: Range limits and centroids of individual species’ modelled habitat areas changed little between present (2000) and future climates. However the total amount of suitable habitat shrank within the initial range limits. Species with the greatest habitat reductions had the smallest proportions of their present habitat areas in refugia (habitat areas suitable under present and future climates), but the largest proportions of their future habitat areas. The absolute areas of species’ habitat protected by legislation decreased, whereas the proportions that were protected changed little. Conclusions: Regional-scale climate change is likely to cause substantial species declines, together with reduced areas of protected suitable habitat. The observed nature of distributional change indicates that long-term regional species conservation will depend more on identifying, protecting, and restoring habitat refugia than on actions to facilitate larger-scale movements.