The Microbial Soil Flora: Novel Approaches for Accessing the Phylogenetic and Physiological Diversity of Prokaryotes

Abstract

The soil is an important interface in nature which is influenced by dif- ferent environmental spheres: the hydrosphere, the lithosphere and the atmosphere. The soil compartment has developed over eons, and passed through many stages of development and maturation. Soil is thus often described as an archive of earth history. All the spheres determine soil characteristics, but the influence of man and modern technology has in- creased significantly since the last ice age. It is therefore reasonable to add a fourth sphere influencing soil characteristics: the anthropo- or techno- sphere. This is a multifactorial web of human influences, the importance of which has increased greatly since the beginning of industrialization. Soil degradation and desertification are catchwords describing fundamen- tal changes in natural soil functions which have led to an irreversible loss of high-quality soils worldwide. The key variables for the development of soils, the rocky subground, the climate and the vegetation have become more and more biased by modern soil tillage practices and inputs of con- taminants and pollutants. Human impacts to soils have contributed much to the modification of the soil as a component of global change.