EN
Spatial distribution of nematode fauna was studied in relation to horizontal heterogeneity of a natural tall-sedge fen in north-eastern Poland. Due to vegetation patchiness at scale of several tens centimetres two distinct habitats can be distinguished – “tussocks” and sites “between tussocks”. Nematode fauna in the soil “between tussocks” was different from that of the adjacent “tussocks” sites with respect to total abundance, generic composition and community trophic structure. On the two sampling dates (in spring and summer) significant more nematodes were found in the “tussocks” than “between tussocks”. Nematode communities were more diverse in the “tussocks” than “between the tussocks”, however the differences between two sites were significant only in spring. Each site had its own dominant genera different from the dominant genera of the adjacent site. Spatial pattern of nematodes was dynamic over time and seemed to be highly influenced by seasonal fluctuations of floods, which make the sites “between tussocks” available for nematodes only when floods recede.