Untersuchungen zum Eichensterben: Aspekte des Stoffhaushaltes von Eichenmittelwaeldern des Weinviertels unter besonderer Beruecksichtigung des atmosphaerischen Schadstoffeintrages : Dissertation
Four oak stands (Quercus petraea & Quercus robur) in the Weinviertel, Lower Austria were studied to improve the knowledge of geochemical processes in oak ecosystems affected by forest decline. Ecosystem inventories, soil moisture studies, immission and deposition monitoring, as well as chemical analyses of the soil solution were carried out. Three oak plots were arranged along a distance gradient to a lime quarry to study the effects of different concentrations of basic aerosols on the deposition of ammonia, nitrate and sulfate. Foliar analysis indicates that mineral nutrition is balanced and sufficient in all stands. So far deposition has not caused significant soil acidification nor release of toxic elements because of the high acid neutralizing capacity of soils. Proton buffering in the forest canopy adds to nutrient leaching of up to 5-54% of the annual cation uptake. Oak-hornbeam stands assimilate more nitogen than pure oaks stands. In general ammonium uptake is more important than nitrate uptake. High concentrations of limestone aerosols in the vicinity of the ammonium/nitrate ratio in throughfall. Nitrogen saturation and soil acidification due to nitrate leaching are not likely to contribute to oak decline in the examined stands. Sulphate inputs and SO2-immissions are high. Chemical analyses of leaves and soil water support these findings. Sulphate input is the leading contribution to soil acidification, mainly from long range transport of air pollutants. During the vegatation period high evapotranspiration led to low soil matrix potentials which were not significantly rised by summer rains during the study period. Consequently, replenishing of soil water content during winter is a precondition for sufficient water supply during the vegetation period.
