The heterogeneity of humus components in a virgin beech forest

A non-random sampling design allowed to distinguish within a virgin beech ecosystem two main components of humus profile heterogeneity. The stratification of the profile into horizons reflects changes in the composition of the soil/litter matrix occurring under the influence of the anisotropic deposition of leaf and wood litter and the stratified occurrence of soil organisms (roots, microbes, animals). The horizontal heterogeneity is mainly influenced by changes in vegetation, in particular the decreasing influence of beech (and the increasing influence of ground vegetation) when passing from the tree trunk base, where the influence of the tree reaches a maximum, to the centre of adjacent gaps where the influence of beech is replaced by that of another vegetation. The use of multivariate methods, used for description rather than for modelling, is suggested to be the best procedure for understanding patterns underlying heterogeneity without a priori assumptions.