Classification schemes for the acidity, base saturation, and acidification status of forest soils in Switzerland

摘要

Soil chemical parameters related to soil acidity were determined for 1450 soil samples taken from individual mineral soil horizons in 257 forest soils in Switzerland, 196 developed from carbonate-containing and 61 from carbonate-free parent material. The distribution of pH values and exchangeable base cations in corresponding pH ranges were related to the capacity and rate of buffer reactions in the soil. Based on this, five acidity classes for individual soil samples were defined.To describe and classify the status of soil acidity and base saturation (BS) of an entire soil body, the pH and the BS of the total fine earth in the soil were calculated from the pH and BS, respectively, of the individual soil horizons and the estimated volumetric content of fine earth.The status of soil acidification of soil profiles was assessed primarily using the total amount of exchangeable acidic cations in percent of the CEC of the fine earth in the entire soil profile. As a second factor, the gradient between the acidity class of the most acidic soil horizon and the estimated acidity class at the beginning of soil formation was used. The application of these classification schemes to our collection of soil profiles revealed the great influence played by the type of parent material. The acidification status of most soils on carbonate-containing parent material was classified as very weak to weak, whereas soils on carbonate-free parent material were found to be strongly to very strongly acidified.In terms of parent rock material, microclimate, and natural vegetation, the results of this study and the proposed classification schemes can be considered appropriate for large parts of Europe.