The stratobios spider populations (Araneae) of forests of the Pripyshminskie bory national park (summer aspect)

Assemblages of spiders, inhabiting a litter of different-type and uneven-age coniferous forests (15, 25 and 70-years pine tree-planting, natural birch-pine, pine-spruce and spruce forests), are studied in "Pripyshminskie Bory" National Park (Sverdlovsk Area). The material was sampled during the summer months (June, July) 1997 and 2002 using identical technique and methods. The samples of litter with size 25 x 25 cm. were passed through the entomology sieve for exclusion of a large size fractions. Spiders from the 'small size remnant' were captured manually. The spiders assemblages of the investigated pine tree-plantings and natural forests are differs. The samples collected in the pine tree-plantings contain more species (18-25) than those gathered in the forest (6-10), with more leveled ration parity of taxa (Shannon index (H') = 2.3-2.7, against H' = 1.3-2.1 in forests). Some species, which were not detected in the forests (for example, Abacoproeces saltuum (L. Koch, 1872), Pocadicnemis pumila (Blackwall, 1841), Tapinocyba insecta (L. Koch, 1869)), are present in pine tree-plantings. Controversially, the samples of spiders from natural forests are characterized by presence of a single abundant species (Diplocentria bidentata (Emerton, 1882)) together with a high ratio of linyphiid-spiders specimens (86-100%). The density of spiders varies from 35.1 up to 95.6 specimens/m2 in pine tree-plantings. Specimens belonging to four families (Linyphiidae, Gnaphosidae, Theridiidae, Lycosidae) are most numerous in the young pine tree-planting (10-15 years), with immature specimens of Haplodrassus sp. and Tapinocyboides pygmaeus (Menge, 1869) showing maximal ability. Only two families, Linyphiidae (2/3 of all individuals collected) and Theridiidae, are numerous in 20-25 and 70 years aged tree-plantings, with dominance of D. bidentata and Robertus lividus (Blackwall, 1836). The density of spiders increases with the age of the forests from 45-53 specimens/m2 in the mixed birch-pine forests, up to 168 specimens/m2 in spruce forest (climax commu nity). Whereas only one species D. bidentata has been noticed as a dominant in the mixed forests, the three co-dominating species, D. bidentata, Erigonella hiemalis (Blackwall, 1841) and Minyriolus pusillus (Wider, 1834), were detected in the spruce forest.