Biodegradation and Humification Processes in Forest Soils
Ingrid Kögel‐Knabner
Abstract
This chapter aims to delineate the major humification processes that operate in forest soils of temperate climates. It discusses the susceptibility of different classes of aliphatic and aromatic compounds classes of forest litter to these humification processes. However, the intensity of the individual processes can be different, depending on the soil environment. The sum of these individual humification processes is expressed in the morphology of different humus types in forest soils. As the horizon sequence in forest humus is directly related to the degree of humification, the pathway of formation of humic substances can be delineated by following the chemical evolution in plant-derived biomacromolecules and in humic substances with depth. The basis of structural investigations of the organic matter of forest soils is a detailed knowledge of the morphological and molecular composition of the parent litter material. Extractable lipids show an increasing contribution of microbial lipids with depth, especially in acid forest soils.