Heavy metal concentrations in Enchytraeidae (Oligochaeta) in the Niepoimageomice Forest

Enchytraeidae were investigated as a part of a broad study of Niepoimageomice Forest ecosystem functioning. Animals were collected in oak–hornbeam (Tilio–Carpinetum) and in mixed oak–pine (Pino–Quercetum) stands. The highest cadmium concentration was observed in oak–hornbeam from the northern part of the forest (32.33±23.22 mg kg−1 dry mass), with lower ones in mixed oak–pine (13.60±21.42 mg kg−1 dry mass) and southern oak–hornbeam stands (11.84±7.52 mg kg−1 dry mass). Lead concentrations were higher in mixed oak–pine (47.73±23.36 mg kg−1 dry mass) and southern oak–hornbeam (52.20±45.19 mg kg−1 dry mass) stands than in northern, oak–hornbeam (9.20±6.46 mg kg−1 dry mass). The copper concentration was similar in animals from all forest types studied (147.94±106.38 mg kg−1 dry mass in mixed oak–pine, 138.35±64.76 mg kg−1 dry mass in northern oak–hornbeam, and 138.27±80.08 mg kg−1 dry mass in southern oak–hornbeam). The lowest concentration of zinc in animals was found in northern oak–hornbeam (1015.27±300.28 mg kg−1 dry mass) and higher concentrations, in mixed oak–pine (2233.81±1825.41 mg kg−1 dry mass) and southern oak–hornbeam (2366.60±1987.52 mg kg−1 dry mass). The concentrations of available metals in litter trended with those in the animals, but only the relation between lead concentration in animals and available lead in litter was significant. The spatial distribution of metal concentrations in the whole forest suggests a relationship between forest type and the content of cadmium, lead, and zinc in animals. The spatial distribution of heavy metal content in enchytraeids was investigated in selected plots as well. The coefficients of variation indicated that lead had the most diverse distribution and zinc the most homogenous.