A comprehensive study of the biology, taxonomy, and ecology of each of the soil biotic groups. The first chapter presents an ecological approach to soil studies. The remaining 42 chapters provide specific information on each of the taxonomic groupings. Contains illustrated identification keys to each group. Some keys go by functional morphological delineations; others lead the reader to classical identification at family, genus, or species levels. Some incorporate descriptions of new genera and species. Especially useful for the study of mesic, xeric, and hydric terrestrial sites. Includes an extensive bibliography.