Rock outcrops as potential biodiversity refugia under climate change in North Patagonia

Abstract

Background: Under climate-change scenarios, rock outcrops, by providing microclimatically diverse habitats, different from those of surrounding zonal vegetation matrix, may serve as climatic refugia and thereby facilitate the persistence of specialist species. Aim: We tested whether rock outcrops of southern temperate latitudes could act as local refugia for a cold-adapted flora in the face of global warming. Methods: We related species composition of 50 outcrops and that of their surrounding vegetation to climatic data at local and regional scales to establish whether species distributions reflected differences that could indicate the existence of climatic refugia. Results: While at a regional scale, species composition of the outcrops across the study area was related to mean annual precipitation and mean annual maximum temperature, locally, southern faces of outcrops had different species and lower maximum temperatures than insolated north faces and surrounding vegetation plots. Conclusions: South faces of outcrops by providing cool microhabitats, and currently harbouring species not found in the surrounding zonal vegetation matrix, could serve as local refugia for heat-intolerant plants and other microthermic organism. The degree of ‘stability’ of these refugia will depend on the degree of future change in climate. Therefore, it is important to plan protected area networks that maximise local environmental heterogeneity, including the protection of rock outcrops both as refugia for cold-adapted species and as potential stepping stones that would allow dispersal of these species between supportive environments through unfavourable ones.