LONG-TERM CHANGES IN WATER AND SOIL CHEMISTRY IN SPRUCE AND BEECH FORESTS, SOLLING, GERMANY

With declining sulfur emissions in western Europe, the degree and time scales of reversibility of soil and freshwater acidification;are of m ajor interest. We analyzed long-term changes (1969-1991) in the chemis try of; bulk precipitation, throughfall water, soil water, and exchang eable base cations in a beech and a spruce forest in Solling, Germany. Time trends in dissolved and exchangeable pools of base cations in th e soils were compared with simulations from a simple mechanistic soil chemistry model to identify the processes controlling long-term change s in soil chemistry. In the early 1970s, profound acidification occurr ed in the spruce and beech soils due to increasing concentrations of d issolved SO4 After 1976, atmospheric deposition of SO4 decreased signi ficantly as a result of reduced industrial emissions. nevertheless, ac idification continued in the spruce soil due to declining atmospheric inputs of Ca and Mg and continuously high dissolved SO4 in the soil. I n the beech soil, with lower deposition levels, smaller declines of ba se cation deposition, and a more diluted soil solution, reduced atmosp heric inputs of SO4 in the 1980s started off a recovery of the soil's base saturation.