REMARKS ON THE EFFECTS OF NITROGEN DEPOSITION TO FOREST ECOSYSTEMS

The effects of increased deposition of nitrogen compounds on forest sites are discussed based on literature data and own results from both earlier fertilization experiments and the ARINUS study area in the Black Forest. The influence on mycorrhiza is stated suppressive as well as stimulating so that no general conclusion can be drawn. The nitrogen nutrition status of coniferous forests is still sub-optimal over wide areas with a yearly deposition of 10-20 kg N ha-1. Under considerable higher input rates the insufficient supply of other nutrients and imbalances in the nutritional status of trees are possible. When discussing 'nitrogen saturation' of ecosystems, the nitrogen storage capacity of soils has to be considered as a decisive factor which varies from site to site. Any actual input/output balance is strongly influenced by the internal turnover processes resulting from former land use. © 1990 Kluwer Academic Publishers.