Forestry management options for water preservation

Forested areas have a high potential for water preservation and are reserves for low polluted water. The long-term survey of groundwater quality shows that even below forest floors water quality drops. Nitrate concentrations increased from the typical output levels of forest ecosystems of 2 to 3 mg/l up to 5 to 6 mg/l and more within the last decades. At the landscape level, a prognosis of nitrate concentrations in the groundwater succeeded by using site parameters (critical load exceedance for N, C-stock in the mineral soil (0-30 em), annual precipitation, C/N gradient between humus layer and the upper mineral soil (0-5 cm), Castock in 0-5 cm and pH (KCl) in 10-30 cm) from the statewide Soil Chemical Survey in a multiple linear regression model. This model explained about 60% of the variance in nitrate concentrations in the groundwater. Thus the first step towards closing the gap between locally related process studies and landscape related practical planning is done.