Enchytraeids (Enchytraeidae, Oligochaeta) in midfield shelterbelts of different age and in adjoining croplands

The objective of this paper was to recognize the influence of forest strips planted (as the shelterbelts) in agricultural area, on adjoining cereal fields basing on the distribution and composition of enchytraeid community. Species composition, density and individual size of enchytraeids were estimated in October and April 2003-2005 along two transects: 6 and 11 years old shelterbelts > ecotones > fields (at a distance of 15 and 50 m. from the wood strip) and in two reference sites: large (about 100 ha) forest stand and the field ("control" field) located in deforested area. The results have been compared with the published results of the previous studies made in the same area four years before (1999-2000). Samples were colleted with soil corer 10 cm[^2] in area and 15 cm deep. Ten samples in each site were taken twice a year. Sixteen species were found in total. The range of density and biomass of enchytraeids for all study sites accounted for 1.6 to 15.3 ind. m[^-2] and 55 to 956 mg f.wt. m[^-2] (i.e. 15-308 mg d.w.) respectively. The lowest density was obserwed in the control field located in the deforested area. However, density and biomass of enchytraeids in the fields accounted for 67% and 47% respectively of those in shelterbelts. Species composition of enchytraeids in the young (2-11 yrs old) forest strips and in the adjacent fields was similar, however different from those in the forest stand and in old (150 yrs) shelterbelt. The response of enchytraeids to grass litter introduced on the soil surface was assessed in the experiment performed in a control field and in the transect of wood strip > field. The 7-10 portions of dried grass Dactylis glomerata (L.), (10 g each) were exposed in each plot for 12 and 18 months. More animals was found in the upper soil laver taken below the exposed litter as well as the density of all enchytraeids and percent share of the dominant genus Enchytraeus increased in the soil after 18 months of litter exposure.