Enchytraeids (Oligochaeta) in the agricultural landscape

Enchytraeids are the most important detritophages in farmlang. Their density, species composition, and body lenght were assessed in four crop fields and adjacent shelterbelts in Turew area (Wielkopolska, West Poland). The density in crop fields varied between 3000 and 13000 ind. m^-2, whereas in woodlots from 7000 to 15000 ind. m^-2. In the absence of earthworms in cultivated fields, enchytraeids contributed to 2-5% of the total biomass of soil invertebrates. Enchytraeid species living in crop fields were not specific of this habitat. The community occurring in the ecotone (between the woodlot and field) was similar to that in the crop fields with respect to the species composition, and to the youngest woodlots with respect to the abundance and body size. Over the last 25-year period, numbers and diversity (H') of enchytraeids in investigated fields did not change but the size of an average individual decreased.