THE ECOLOGY OF MICROBIAL COMUNITIES IN SOILS AND GYPSUM CAVES IN TAIGA REGION (RUSSIA)

Semikolennykh A.¹, Gorlenko M.², Ivanova A.²
¹ Institute of Geography, Moscow
² Moscow Lomonosov's University, Soil Faculty
semik@biolith.msk. ru

The functional structures and population structures of microbial fungi & bacterial communities have been studied in the gypsum caves of Archangelsky Region (North European part of Russia, 64º 32' n. lat., 43º 15' e. lon) within a natural sub-area of the north taiga zone. Some caves & soil samples have been selected for the microbiological investigation. The poor substrates and rich organic samples have been researched by way of incubation on media with different conditions, destructive tests within a field, multi-substrate testing, and model experiments.

These soils and caves have approximately the same microbial biological mass and common taxonomic versions, though there are some strict differences within a microbial community's structure (relative taxonomic abundance & object frequency) and its functional activities as well.

The cave fungi communities may be differed from soil types by way of their high degree of homogeneity (community uniformity ratings E=0.95-0.99), i.e. by their rare species, although the same taxonomic types have abundant rating terms (frequently > 30%) under total absence of scanty species. In other words, one could see massive discrete cave substrate being emerged by its single monospecies' population.

The hydrolytic organisms are less active under low temperatures, therefore fast destruction of the complex organic cave material has not been observed. But the constant low temperatures may cause an adaptation process (the so-called psychrophilic pool appears) of the oligotrophic microorganisms. For an example, the quota of microorganisms growing in 5ºC from microorganisms growing in 25ºC for mineral soil horizons is 0.05% and for mineral cave sediments is 20%, respectively.

The process of substrate consummation by the microorganism communities from the cave sites proceeds in slow motion, along with less energy of reaction.

Thus, the cave environment produces a rapid selection of the psychrophilic & oligotrophic forms (without any rivals), which may be observed in organisms within a cave that contains surface superficial water & other material types.