ELEMENT OUTPUT APPRAISAL FROM FOREST ECOSYSTEMS OF NORTHEASTERN BAVARIA, UNDER STRESS FROM ATMOSPHERIC DEPOSITION, BY HYDROCHEMICAL SPRING WATER ANALYSIS

In the mountainous regions of northeastern Bavaria (F. R. G.), 400 forest springs in the Fichtelgebirge and the Frankenwald were sampled between 1989 and 1991. The resulting hydrochemical data characterize the variability of spring water chemistry in space and time. Springs are regarded as output of forest ecosystems which can indicate deposition climate and ecosystem reaction to acidic deposition. In both areas high sulfate concentrations (SO4 mean = 200 muMol/l) in spring waters indicate the impact of acidic deposition. The highest sulfate concentrations (SO4 max = 965 muMol/l) were reached in the northern parts of Frankenwald and the eastern parts of the Fichtelgebirge. The springs of the Fichtelgebirge, which is dominated by granites and phyllites, are generally for more acidified (pH(mean) = 5.13) than those of the Frankenwald (pH(mean) = 6.31), which consists mainly of schists and does not receive comparable precipitation amounts. Acidification in the Frankenwald is concentrated at higher elevations close to the former East German border. In the Fichtelgebirge low pH is common to upper regions above 800 m altitude and, accompanied by high concentrations of aluminium, reaching 189 muMol/l. Due to the comparatively base-rich parent material, the Frankenwald springs reach higher concentrations of calcium and magnesium but lower concentrations of potassium than those of the Fichtelgebirge. From the large number of investigated forest springs a detailed geographical picture of spring water acidification can be constructed. Forest springs can be used to identify sensitive forest ecosystems before damages become obvious in forest canopies.