A survey of the health of Fagus sylvatica in southern Britain

Health of beech trees at 72 sites was assessed using crown thinness, crown architecture and leaf chlorosis as criteria. About 25% of all trees surveyed were in poor health as assessed by crown thinness and architecture. Incidence of chlorosis was generally low (5%). Sites of high nature conservation interest for beech showed substantially poorer tree health than other sites. Disturbance, tree age, the openness of the stand and soil characteristics, especially pH and drainage properties, were closely linked to tree health as assessed by crown thinness and architecture. Chlorosis was most closely associated with the amount of free calcium in the top soil. Crown thinness was positively related to SO ₂ concentration, whereas crown architecture was better in areas with a high concentration of NH ₃. Trees had thinner and more chlorotic crowns where they had experienced the most intense drought in 1976. For all cases where significant relationships were found between pollutant levels and tree health on acidic soils, health was worse on sites receiving high levels of the pollutant concerned. On calcareous soils tree health was better with higher levels of pollutants. The relationship between air pollution and tree health on acidic soils is consistent with the soil acidification hypothesis that has been proposed to explain forest decline. -from Authors