Anthropogenic impact such as deposition of organic or mineral substrate or removal of organic surface layers and organic mineral soil affects litter mineralisation and humification and thus the corresponding O and A horizons. Sites characterised by such an imbalance are described by the type of the parent material, content of carbonate, provision of basic cations, kind of vegetation, and type and decomposability of litter. These properties can give an indication whether the humus form is more likely to develop into a mull-like humus form or a humus form with an organic surface layer and to what extent it is significantly influenced by soil moisture.

IM          Initial Mull

IA          Initial humus form with organic surface layers