Spatial distribution of spiders (Aranei) and other groups of soil macrofauna in the arctic tundra of northeastern Taimyr, Russia

Abstract

. Numerous materials have been pro-cessed on soil invertebrates collected by the International Arctic Expedition of the Institute for Evolutionary Morphology and Animal Ecology, Russian Academy of Sciences in 1991 in arctic tundra of eastern Taimyr, near Pronchishchev Lake. The samples re-vealed six spider species of the only family Linyphiidae, all of them being typical purely arctic. The most common species were Erigone psychrophila Thorell, 1872, Hilaira gertschi Holm, 1960 and Semljicola arcticus (Eskov, 1989). The first two species inhabited all the studied biotopes, whereas E. psychrophila was su-perdominating in each of these biotopes. The fauna of spiders of zonal communities was poorer than that in intrazonal ones (3–4, vs 4–6 species). Spiders play the main role in the structure of the soil macrofauna population of arctic tundra of eastern Taimyr. This group is the most diverse, is the most vast component of the macrofauna, and most earlier in the activity after the winter diapause. The second important group are the beetles (Carabidae and Staphylinidae). While spiders are primary in abundance and the share in the total macrofauna in zonal communities, the intrazonal biotopes are characterized by approximate parity of these groups. The share of spiders in the macrofauna decreases during the summer due to diapause end in other invertebrate groups: the soil samples show a decrease from 38% in June to 30% in July, the data from pitfall traps show a decrease from 75% to 38%. In soil samples, spiders comprised 23–50% of the number of all soil macrofauna in the beginning of vegetation season (June), while declining to 18–36% in the mid-season (July). The total number of soil macrofauna in zonal communities is about twice lower on the average than that in intrazonal ones (82, vs 149 spms/m 2 ); the number of spiders is 1.5 times lower (31, vs 48 spms/ m 2 ), that of beetles is almost 4 times lower (16, vs 62 to get a more complete representation of araneofauna of local arctic tundra of eastern Taimyr.