Fungal and bacterial biomass in tundra soils along an arctic transect from Taimyr Peninsula, central Siberia

Microscopic analyses of tundra soils from northern central Siberia, Taimyr Peninsula (74.5°N, 98.5°E) were performed in order to investigate spatial variation of fungal and bacterial biomass. Biomass figures of fungi and bacteria (µg C g–1 dry wt.) were measured from 11 permafrost soil pits. Fungal biovolume of up to 3.5 mm3 g–1 dry wt. (median 0.19 mm3 g–1 dry wt.) and a maximum hyphal length of 393 m g–1 dry wt. (median 21 m g–1 dry wt.) were determined. Fungal biomass was found up to 455 µg C g–1 dry wt. (median 24 µg C g–1 dry wt.). The amounts generally decreased with depth but increased within organic horizons. Little fungal biomass was found in the unvegetated soils or deep horizons above the permafrost table. Bacterial counts ranged from 0.16 to 7.38*109 g–1 dry wt. and bacterial biomass ranged from 0.68 to 20.38 µg C g–1 dry wt. (median 6.19 µg C g–1 dry wt.) because of small cell volume (median 0.04 µm3). Microbial biomass was generally dominated by fungi as shown by the ratio of fungal to bacterial biomass, which was between 0 and 174.1 (median 4.5). Plant cover and soil organic matter content were found to be the important keys in understanding microbial ecology in arctic tundra soils.