Soil nutrient status of natural soils in Europe

So far, a map summarizing the nutrient availability of natural soils in Europe is not available. Such a map is required e.g. for the prediction of vegetation changes due to anthropogenic depositions and climate change. In this project the soil map 1: 1.000.000 of the European Soil Data Center (ESDAC) of the European Commission was used. For each soil mapping unit (SMU), the dominating FAO soil type was attributed to a ten-part nutrient classification system. In this expert-based classification, the soil types are ranked by the nutrient supply of the soil, in which the maximum plant growth is to be expected in the middle range (code number 4) where the nutrient supply is well balanced. In addition to the expected composition of the nutrient supply, the intensity of nutrient supply and typical deficiencies are the decisive criteria for the classification of soils. Thus, potential nutrient limits on carbonatic soils (code number 5 and 6) are separated from those on acid soils (code number 1 and 2). Another four classes were required to characterize soil types which are strongly dominated by one specific cation (code number 7), which are water-saturated (code numbers 8 and 9) or which are unrecognizable due to coverage by glaciers, waters, or cities. Since the nutrient supply of some soil types varies in a wide range, the classification of soils is not always clear. In such cases additional information on geology was used. For rendzinoid soils in mountains the altitude range derived from a DTM was used to distinguish between the more and less favorable subtypes. This map and the evaluation scheme presented was the basis for a macroecological study on the question of compensatory soil effects at the warm-dry distribution limit of European tree species (Mellert et al. 2017).