Plant community dynamics in a calcareous grassland under climate change manipulations

This study investigates the effects of field manipulations of local climate to determine the potential impact of climate change on plant community dyn amics in a calcareous grassland. The experimental site is located in a gras sland at the Wytham estate, Oxfordshire, UK. The one hectare study area is within a 10 ha abandoned arable field on Jurassic corallian limestone. Two climate change scenarios were used: warmer winters with increased summer ra infall and warmer winters with summer drought. Plant cover and species rich ness were significantly increased in plots receiving supplemented summer ra infall, while the amount of litter was significantly reduced. Litter format ion was significantly increased by winter warming and drought. The response s of the plant community to the climate manipulations were related to the l ife-history attributes of the dominant species. Seedling recruitment was li mited by microsite availability, which also varied in the different climate manipulations. The results are discussed in terms of successional dynamics . They suggest that warmer winters may delay succession, as gap formation i n the sward will provide sites for colonisation of annuals, thereby enablin g their persistence in the sward. Under wetter conditions during summer, pe rennial grasses tend to close the sward, thereby inhibiting the establishme nt of later successional species.