GEOMON

Hydrological and chemical data from the GEOMON network, which encompasses fourteen small forest catchments in the Czech Republic, has been collected. Unified field and laboratory methods have been used since 1994, but many catchments have been monitored much longer. Bulk deposition as well as throughfall deposition and runoff of ecologically important components have been measured on a monthly basis. A marked decrease in the atmospheric deposition of pollutants occurred as a result of the desulfurization program adopted in the CR between 1993 and 1998. However, the throughfall deposition of sulfur, which incorporates wet and dry portions, is still substantial, especially at higher elevations. The recent return to the use of coal heating in the residential sector may explain the increase of the sulfur deposition in some areas.

The proportion of dry deposition of sulfur measured under coniferous canopies represents 30–70 % of the total deposition. Much less deposition was measured under canopies of deciduous trees. Atmospheric deposition data has shown that nitrogen compounds have become the most important source of acidification since 2000, caused by an increased road traffic. The direct impact of air pollution (including ozone), an abundance of nitrogen, acidification and toxic metal mobilisation are probably the primary causes of forest decline. Acute weathering changes, insect pests, or fungal infections act as secondary stressors.