Acidification of forest soils is dependent on the tree species for several reasons. One reason is that the deposition to deciduous tree species normally is considered lower than to coniferous tree species. This study therefore considers the differences in deposition to different tree species in Denmark. Canopy throughfall and precipitation were collected during the period 1986 to 1999 at three trial species experimental sites in Denmark. At each site the species Norway spruce, sitka spruce, Douglas fir, beech and oak were studied. The paper presents and discusses the differences in canopy exchange processes and dry deposition in different tree species and at different locations

Taking into account the results of environmental monitoring in forest ecosystems (European Level I- and II-Programme) showing high degrees of soil acidification and still a widespread exceedance of critical loads by deposited sulphur and nitrogen compounds, the programme of differentiated forest protection liming should continue with site specific doses. On the other hand the programme to restore forest ecosystems with higher stability and to a large extent balanced nutrient cycles has to be carried out in order to minimize internal acid-generating processes

Forest soil condition in Slovakia harmonised with the programme ICP Forests has been monitored since 1988. There are presented some results of the first complete survey for 111 observation plots and three sampling depths (overlaying humus layer, 0-10 cm and 10-20 cm layer of mineral soil). Geological and geochemical diversity has resulted in rather differentiated forest soil condition and soil properties in Slovakia. That has strong effect on sensitivity to soil acidification as well as it brings other risks of air pollution impact

Forest ecosystems water balance research is very complicated because of forest influence upon individual components of the water balance. Global climate changes represent a real threat for forest ecosystems. In hydric area these changes concern especially thermal balance and resulting increased evapotranspiration, time and spatial distribution of precipitation