Bark lesions on beech (Fagus sylvatica) and their relation to epiphytes and site variables in Scania, south Sweden.

Beech bark lesions, (Cryptococcus fagisuga), the most common lichen and fungi epiphytes on beech (Fagus sylvatica) stems were studied at 48 sites in Scania, south Sweden. Different site variables and the influence of nitrogen deposition were investigated. The field vegetation and lichens were used as biological indicators by calculating indices for nutrition status, toxicity, pH, light and moisture. Two sets of lichen indices, from Hultengren and Ellenberg, respectively, were calculated. Beech bark lesions were found at 25 sites and were more frequent at more polluted sites with much C. fagisuga and Lecanora conizaeoides, and on largish trees. Algae cover and C. fagisuga were positively correlated. Both preferred sites with no direct light exposure, high nitrogen deposition and low pH. The two sets of lichen indices were fairly comparable for toxitolerance, light and pH. In this investigation, Lepraria incana was the most frequent of all epiphytes, often determining the value of the lichen indices