This book provides a deep insight into the community organization and metabolism of the microbiota of a soil ecosystem presenting the results of a large number of analyses and investigations carried out by using both conventional typing methods and the statistical methods of numerical taxonomy on the composition, changes and flucutations of bacterial, actionmycete, fungal, yeast, protozoan, et. populations of diverse plant, animal and soil microhabitats. The author focuses his attention primarily on the fundamental patern of cummunity organization, the general characteristics of which are independent of the taxonomic composition and of the features and environmental stresses of that particular soil ecosystem in which the community grows and reproduces.