How many isopod species can live in a small moderately polluted deciduous forest?

Abstract

Terrestrial isopods were collected in small moist mixed deciduous forest surrounded by settlements, gardens, and roads. Forest locates in Kaunas region, Lithuania. Deciduous trees Coryllus avellanus, Fraxinus sp., Quercus robur dominates in forest. The ground flora is dominated by Anemone nemorosa, Hepatica nobilis, Mercuralis perennis. Survey of isopods and myriapods was random, but continuous throughout a year, except the winter. Number of sites examined in forest ranged from 10 to 15 each time of observation. Isopods were sampled by hand, in shelters. During 2015 – 2017 were collected a total of 11 species of terrestrial isopods, 18 species diplopods including rare diplopod species Trachysphaera lobata. Species as T. ratkhii, O. asellus, A. vulgare were abundant. All species coexisted in the same small forest, but they occupied slightly different biotopes. T. ratkhii and O. asellus were mostly found under fallen barks, in old rotten stumps, meanwhile A. vulgare kept under the dry bark of standing trees. Investigated forest was moderately contaminated by some wastes (fragments of polyethylene film, plywood’s, bricks) of human activities. Wastes in the forest did not make the forest more nicer, but for some isopods and invertebrates as microsnails, slugs, myriapods, insects and mites such artificial shelters were useful. The results indicate that combination of the natural habitat and some artificial shelters can have a beneficial effect on terrestrial isopods diversity.