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 (MUCS). In the unpolluted area, 17 species were identified (from 6 to 13 in different sample plots), the average density was 13 666–44 903 specimens/m2, average (raw) biomass 1357–3699 mg/m2. Near the smelter, population density, biomass and species richness were reduced by 80, 20, and 2.4 times, respectively. However, the diversity of communities changed only slightly, and the diversity structure of enchytraeids in the impact zone is potentially comparable to the background’s. In the background zone, the highest values of density and biomass were concentrated in the upper layer (0–2 cm) of 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 (lower part of the litter), which contained the highest concentrations of metals. Changes in the vertical distribution of enchytraeids are not thought to be related to pollution effects.