Vegetation, recent pollen deposition, and distribution of some non-pollen palynomorphs in a degrading ice-wedge polygon mire complex near Pokhodsk (NE Siberia), including size-frequency analyses of pollen attributable to Betula

Vegetation distribution and pollen deposition were studied in a complex of degraded ice-wedge polygon mires near Pokhodsk (NE Siberia) in order to obtain insight in the relation between actual vegetation and pollen deposition in microtopographic landscape elements. Pollen surface samples with 1 m spacing were collected along a transect and compared with the vegetation at the sample quadrats, with the vegetation in the adjacent quadrats, and with the vegetation at larger distances. A clear regional pollen signal of plants growing outside the study plot was found in the large central depression for pollen types attributable to Comarum palustre, Betula, and Ericales. Local pollen values (i.e. exceeding the regional background deposition values) are restricted to quadrats where the associated taxa are present within 1 m distance (e.g. Comarum palustre, Betula and Rubus chamaemorus). Several plant taxa (e.g. Cyperaceae, Ericales, Pedicularis and Sphagnum) show both high and low pollen deposition values in quadrats where the taxa actually occur, indicating differential pollen production/deposition among specimens of the same taxon. A local signal of grasses and Salix is not noticeable and the pollen signal of these taxa is mainly attributable to plant specimens growing in a larger area. The non-pollen palynomorphs include principally testate amoebae, which dominate on the polygon ridges. Size-frequency analyses show that pollen attributable to dwarf Betula has in the NE Siberian Arctic a large morphological variation.