The effect of climate change on Fagus sylvatica in southern England woodlands
In the 20th century, forests and woodlands in the UK have been under increasing pressures arising from population growth, industrialisation and the spread of urban areas and infrastructure as well as changes in climate. In the New Forest, over the 20th century forestry practices have gone through change with the implementation of silvaculture (1920 to 1980) and subsequent re-establishing of mixed deciduous woodlands. After the storms of 1987 and 1990 the parlous health of beech (Fagus sylvatica) was very evident with the high loss of these trees and the decision by the Forestry Commission to rely on natural regeneration rather than programmed planting. This thesis examines the possible impact of climatic and environmental factors on the heath of beechand its future domicile.
Analysis of climatic data for the New Forest and other areas of beech woodland in the UK showed positive trends in mean temperatures and changes in the seasonal pattern of rainfall together with more intense precipitation. Reference crop evapotranspiration increased in summer months and with declining summer rainfall suggested that summer water shortage may negatively impact on beech in the New Forest.
Controlled environment experiments with juvenile stock of beech and hornbeam (Carpinus betulus) highlighted the impacts of temperature, photoperiod and chilling on budburst and of watering on senescence. The research also embraced canopy density and phenological timings of mature beech trees.
Beech budburst, from three data sets covering the period 1753 to the present day was advanced by warmer temperatures during February to April. Over this period, increasing mean spring temperatures together with slightly later autumn senescence has resulted in a longer growing season.
The results suggest that Fagus sylvatica is probably in decline in its traditional locations in southern England.