ECOLOGICAL CONDITION OF FORESTS AROUND THE EASTERN PART OF THE GULF-OF-FINLAND

The effects of air pollutants on forests around the eastern part of th e Gulf of Finland were studied by measurement of the sulphur and calci um content of pine needles and evaluation of the ecological conditions of pine forests. Several parameters for pine trees and their needles were chosen as well as the species composition and condition of epiphy tic lichens. Very high pine needle S- and Ca-contents were measured in the vicinity of the Narva and Slantsy plants. In this region both the acid and basic pollutant load is massive, partly neutralizing each ot her. It is suggested that the total load will, sooner or later, cause unexpected environmental damage. Wide 'lichen desert' areas were detec ted around Narva and Slantsy. Near the margins of these areas extraord inary epiphytes on pines were observed namely Xanthoria parietina (L.) Th.Fr. and red-coloured green alga Trentepohlia umbrina. They are reg arded as indicators of alkaline pollution. The lowest pine needle S- a nd Ca-contents of the study area were measured in south-eastern Finlan d. The condition of pine forests and their needles was, however, bette r on the neighbouring Karelian Isthmus although the species number of epiphytic lichens was very low and the condition of the lichens was po or. It is suggested that these most sensitive indicators of air pollut ants are damaged by pollutants from St Petersburg and Narva. Vast virg in forests of the Karelian Isthmus act as pollutant sinks reducing the effect of pollutants on trees. On the Finnish side intensive forest m anagement has been carried on for many decades making forests and tree s more sensitive to pollutants.