Abstract/Summary

The impacts of climate change on common beech (Fogus sylvatica) in Southern England are considered. Analyses of monthly temperature, rainfall (1914-2011) and reference crop evapotranspiration (ET0, 1929-2011) were made for four sites with established beech populations; (Wilverley, Forest of Dean, Burnham Beeches and Thetford Forest). Spring, summer and autumn temperatures in the 2l5t century were consistently higher than any time since 1914 but winter temperatures show no trend. July rainfall has shown a downward trend since 1914. ET0 has increased substantially since 1969, especially in spring and autumn, mainly due to increased sunshine hours, resulting in less favourable summer soil moisture conditions. Results were compared to the Forest Commission Ecological Site Classification for the suitability of beech, which uses baseline 1961-90 climatic data. Both accumulated temperature and moisture deficit have increased substantially which makes beech more marginal at the sites. Three sets of phenological data, including the Woodland Trust citizen science data set (2000- 2014) and the Marsham record (1753-1947), were analysed with similar results. Bud burst was advanced with warmer temperatures in February, March and April. Leaf fall was delayed by warmer temperatures in August and/or by greater rainfall in September and October. Bare tree was delayed when October temperatures were greatest. Experimental results on the phenology of beech and hornbeam supported the above effects of temperature on bud burst and of increased soil water on delaying leaf fall. An analysis of Forestry Commission canopy surveys suggested that low rainfall and/or the occurrence of masting decreased canopy cover of beech. The thermal and moisture conditions at all sites have become less favourable to beech and likely to continue to worsen if ET0 and temperatures continue to increase. Though the rates of change are similar at all sites, the impact will be less in the wetter Forest of Dean.