Community structure of Lumbricidae in beech woodland of the Bieszczady National Park, Southeast Poland

Abstract

As ecosystem engineers, earthworms play a key role in the soil environment. However, due to increasing anthropogenic pressure, soil organisms, including earthworms, are being threatened by habitat loss. In this study, we undertook a qualitative and quantitative investigation of earthworms of the family Lumbricidae in four types of Carpathian beech woodland (Fagetum carpaticum), characterized by their understory vegetation (I, F. c. festucetosum drymejae; II, F. c. typicum; III, F. c. lunarietosum; and IV, F. c. allietosum), in the Bieszczady National Park (Eastern Carpathians, Southeast Poland). At each investigated site, soil monoliths (25 cm × 25 cm × 25 cm) were examined by hand sorting. Earthworms were expelled from deep soil layers using a weak formalin solution (0.4%). Depending on the phytocoenosis, 7 species of Lumbricidae were identified at each of the sites I, II, and III and 10 at site IV. Site IV (F. c. allietosum) differed significantly (P < 0.05) from the other three sites with respect to earthworm biomass (59.71 ± 39.53 g m−2) and the Shannon-Wiener diversity index (0.52 ± 0.12). Although present three decades ago, the deep-burrowing species Octodrilus transpadanus and the litter-dwelling species Dendrobaena octaedra were not found at site IV in the present study. We suspect that these two species may have been displaced by the invasive Lumbricus terrestris, which was not found at the same site in the 1980s. Such observations warrant further investigation to verify the predicted effects of an invasive earthworm, including the potential effects on soils and other fauna and flora, which have been documented in numerous countries.