Soil chemistry depth gradients as characteristic state variables of forest ecosystems

Based on model concepts and on analyses of the soil solution and the soil solid phase we present a procedure to predict the cation composition of the soil solution from solid phase properties. For the intended prediction, the aluminum (or base) saturation (NH4Cl extraction) of the soil exchange complex yields the best results. This parameter shows distinct gradients through a soil profile, and these gradients can be used to characterize the state of the ecosystem. We suggest to utilize this parameter as an additional criterion in the practice of forest site classification.