ENCHYTRAEID COMMUNITIES OF BIRCH FORESTS IN VICINITIES OF THE MIDDLE URAL COPPER SMELTER

Enchytraeid communities were studied in the upper soil of birch forests in areas within the pollution gradient of emissions from the Middle Ural Copper Smelter. In the unpolluted area, 17 species were identified (6 to 13 in different sample plots); the average density was 13 666- 44 903 ind./m², and the average (raw) biomass was 1 357- 3 699 mg/m². Near the smelter, the population density, biomass, and species richness were reduced by 80, 20, and 2.4 times, respectively. However, the communities structure of diversity changed insignificantly, and the diversity of enchytraeids in the impact zone is potentially comparable to the one of the background zone. In the background zone, the highest density and biomass values were concentrated in the upper layer (0- 2 cm) of the soil, corresponding to the forest litter (61 and 63%, respectively). In the impact zone, the vertical distribution of enchytraeids was different: density (59%) and biomass (61%) were redistributed to the underlying (2.1- 4 cm) layer (corresponding to bottom layer of the litter) containing the highest concentrations of metals. Changes in vertical distribution of enchytraeids are not expected to be related to pollution effects.