Pedogenesis of Chernozems in Central Europe - A review

Since Dokuchaev's investigations of Russian Chemozems, Central European Chemozems were established as steppe soils, with their pedogenesis dominated by humus accumulation as a result of dry continental climate and steppe vegetation, with carbonaceous parent material and bioturbation as other prerequisites. The WRB-FAO classification defined Chemozems by their morphological characteristics, but was biased by the climo-genetic formation model. However, the assumption that modem Central European Chemozems are relics of steppe soils conflicts with palaeobotanical evidence from an early reforestation that started in the Late Glacial, and also with pedological studies that dated Chemozem formation to the Early Holocene. In this review we compile the most important literature on pedogenesis of Central European Chemozems since the 1920s, according to the soil forming factors climate, time, vegetation, relief and man. Our review demonstrates that there is no consensus on the factors controlling the formation, conservation and degradation of Central European Chemozems in published literature. We found that (1) no absolute time of formation could be stated so far, and that (2) Central European Chernozems formed not only under steppe but also under forest vegetation; (3) the spatial distribution of Chemozems and Phaeozems did not correlate with climate conditions or topographic position, and (4) until now no other factors were considered to be responsible for Chemozem development. Recent studies showed that these unknown factors could include anthropogenic activity and vegetation burning as they could form black soils or strongly affect the composition of soil organic matter. We concluded that not all soils classified as Chemozems in Central Europe are steppe soils and thus, as they do not necessarily reflect past climate, the classification may be misleading. (c) 2007 Elsevier B.V All rights reserved.