Notes on the spatial distribution of some spider species (Araneae) in a north Norwegian birch forest

In June-August 1968 quantitative samples were taken on the ground in the relatively dark Loc.I and the more open Loc.II, in the moss cover from the upper green third (level A) and from the lower two thirds (level B), at Loc.I also in pure leaf litter. For some spider species spatial segregation (vertically and horizontally) is discussed. The A-layer at Loc.I was dominated by the fairly large Hilaira herniosa (33.1 %) and the medium sized Centromerus arcanus (10.3 %), the small sized Tapinocyba pallens was scarce (3.7 %). In total differences were less clear (17.3 - 22.1 %). T. pallens dominated (43.6 %) in the litter samples, the other two were more scarce. T. pallens was scarce at Loc.II (in total 1.1 %). Here the light coloured Diplocentria rectangulata dominated at the B-level (34.4 %), and the dark pigmented Minyriolus pusillus dominated at the A-level (21.5 %). The former was not found at Loc.I, the latter was scarce (totally absent from the litter samples). A small sweep net material from the two field layers indicates some faunal differences compared to the moss and litter.