Microclimates buffer the responses of plant communities to climate change

Aim Despite predictions of high extinction risk resulting from climate change, range expansions have been documented more frequently than range retractions, prompting suggestions that species can endure climatic changes by persisting in cool or damp microclimates. We test whether such microrefugia' exist. Location The United Kingdom. Methods We examine fine-scale changes in the plant communities of a coastal grassland over a 30-year period in which spring temperatures increased by 1.4 degrees C. We look at whether changes in community composition and local colonizations and extinctions are related to microclimatic conditions. Results Our findings suggest that while community reassembly was consistent with warming, changes were smaller on cooler, north-facing slopes. Closer inspection of the patterns of species turnover revealed that species with low temperature requirements were able to persist on cooler slopes, while those with high moisture requirements suffered similar decreases in occupancy across all microclimates. Main conclusions Our results suggest that cooler slopes may act as microrefugia, buffering the effects on plant communities of increases in temperature by delaying extinctions of species with low temperature requirements.