Recently extensive decline in the quality of forests has been reported in Europe and North-America. The deterioriation of the forests has been associated with the atmospheric deposition of acidifying and eutrophying compounds. The general aim
of this thesis is to identify and clarify the spatial and temporal variability of this phenomenon. A detailed study was done in forest stands at the « Veluwe » in the central part of the Netherlands. A more general study was done at an European scale. - (AGD)