Long term trends in atmospheric deposition and seepage output in northwest German forest ecosystems

Long term trends of element fluxes in atmospheric deposition and of concentrations in seepage output of seven coniferous and deciduous forest stands in northwestern Germany have been evaluated for the period 1981 - 1994. Decreasing deposition rates of SO4 (50 - 70%) and H+ (60 - 80%) occured al all sites concomitant with the decline of SO2 emission rates in the former Federal Republic of Germany. Deposition of Ca, Mg, and K decreased at the Selling and Gottinger Wald stands. During this period no consistent trends in the flux rates of NH4 and NO3 were apparent. Sulfate concentrations in soil solution decreased at the Selling and Gottinger Wald stands, whereas an increase occured at Lange Bramke south slope. As a consequence of reduced deposition and mobile anion concentrations a decrease of Ca, Mg, K, Al, and Mn in soil solution has been observed at the Selling stands. At the other stands trends of cations in soil solution are not consistent. Nitrate concentrations in soil solution decreased at the Gottinger Wald. A rising tendency with great fluctuations of NO3 concentrations occured at the Selling spruce stand.