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LABORATORY FOR SOIL ECOLOGICAL FUNCTIONS
MAIN GOALS AND TASKS
The main directions for scientific research and most important achievements for the latest 10 years:
The main direction of research is the structural and functional organization of soils and edaphic biota in ecosystems of the boreal zone.
The basic objects of study are unimpaired biogeocenoses of the southern taiga on the territory of the Central Forest State Biosphere Reserve (CFSBR), anthropogenicly transformed landscapes of Middle and Northern Russia, man-caused disturbed and swamped soils of western Siberia.
The members of the Lab take part in Russian and International Research Programs and Projects on the following themes:
On the basis of long-term stationary studies of soil processes dynamics in unimpaired southern taiga’s landscapes on the territory of CFSBR it was established that the differences in the structural and functional parameters of the soils in different types of biogeocenoses were stipulated mainly by the mechanisms of self-regulation, thanks to which characteristic rates of organic substance transformation and biogenic elements circle became established. It was shown that adaptive and regulatory possibilities of biota allowed the viewing of the soil as a self-regulating subsystem of biogeocenoses, possessing an ability not only to perceive external influences, but at definite extent to transform them into the direction, smoothing the expression of unfavorable factors. This process manifests the environment-forming function of edaphic biota.
Ecologic evaluation of microbial resources of the soils of basic types of biogeocenoses of Central Russia was carried out, which allowed revelation of both common, inherent to the soils of taiga zone patterns in microbial association organization, and specific traits in content and functioning of microbial complexes, determined by soil type or seasonality.
The data of long-term microbiological studies on spatial and functional organization of microbial associations in different types of biogeocenoses of the southern taiga were generalized (by the example of the CFSBR). The relation between ecological indices, characterizing microbial diversity of soils, and the rate of going in the soil processes allows to make a conclusion that the natural changes in the character of organic substance dynamics in the soils under study represents the consequence of differently directed strategy of representatives of different groups of biota.
A comparative analysis of structural and functional characteristic features of microbiota in the soils, which are different in climatic and natural conditions, was carried out. It was shown that micromycetes diversity was determined mainly by latitudinal and zonal location of the soil.
A qualitative and quantitative structure of micromycetic complexes was studied for different stages of various model substrates decay. It was established that the species composition and the process of micromycetes succession under decay of different plant remains was connected with the degree of hydromorphism of the soil.
The interactions of micromycetes with basidial mycelia were studied in the course of three-year exposition of model plant substrates in the bottom layer of undisturbed spruce forest in the CFSBR. It was revealed that relative ratio of the species of micromycetes suppressing and stimulating the development of basidiomycetes on the same substrates in different biogeocenoses practically did not differ.
A comparative synecological analysis of edaphic and aquatic mycobiota was undertaken. The specific traits of mycetes distribution in two environments were established. On the basis of micromycetes reaction to harmful influences, a generalized summary of ecological self-descriptiveness of mycological parameters was given.
An aftereffect of a ground fire on bacterial complex of lowland turfs was analyzed. It was shown that it was expressed in 1-3 orders of the lowering of the total number of bacteria, in increase of relative abundance and diversity of actinobacteria resistant to desiccation. In a year after the fire on the obliterating with vegetation areas, actinobacteria were dominating that evidenced to the lower rates of restitution of disturbed by the fire areas.
Southern taiga. CFSBR.
In the soils differing in aeration conditions and organic substance content, a search for micromycetes producing phenoloxidases and peroxidases was undertaken. It was shown that the most active producers of phenoloxidases and peroxidases were dark-colored micromycetes.
A generalizing description of bioindication potential of microscopic fungi at different levels of organization (association, population, organisms) was given. As the most sensitive indices at the level of fungal associations, the structure of biomass, taxonomic diversity, the part of melanizated forms were given; those at the level of population were the variations of isoenzymatic spectra and those at organism level were the growth rate and macromorphological characters, production and germination of spores.
A method of laboratory biotesting of natural media and objects toxicity with the use of the fungal culture of Fusarium oxysporum Schlecht was suggested. Micromycetes showed different sensitivity to hymates in the nutrient medium depending on the pigmentation of mycelium.
The effectiveness of bioremediation of the oil-polluted soils by intruding of microorganisms was studied. It was established that activity of pure cultures and their associations were dependent upon the level of pollution and type of the soil. Under introduction of bacterial-fungal associations in the soils at low level of pollution (until 5%) bacteria were more effective, while at higher oil content the role of fungi increased. From the strains studied the potential bioremediants were picked out, which could be used for creation of effective biopreparation for refining of the soils polluted with oil at various levels of pollution.
The peculiarities of spatial distribution of edaphic invertebrates were studied in the regions with different natural and climatic conditions. The optimal size of sampling for accounting of the real number and species diversity of invertebrates-indicators in the soil processes was determined.
It was revealed that feeding activity of soil animals did not stop in winter time under the snow, despite the temperatures of air lesser than -20°Ń. This demonstrates the fact that detritus food net continues to function during the whole year round and not only in the warm period.
An influence of protein resources on edaphic Polychaeta propagation was studied. An existence of the optimal protein concentration for enchitreid propagation was shown. Both increase and decrease of this concentration leads to the drop in breeding.
Under analysis of biomass distribution of soil inhabitants of the regions with different natural and climatic conditions, its dependence on resources of microorganisms and not on resources of dead organic substance was shown.
The leading role of climate continentality and historical factor in formation of ecological structure in oribatid communities was shown. It was demonstrated that upon progression to the east through the continent, the role of surface forms was increasing and that of bottom ones was decreasing.
As a result of cartographic studies it was established that existing in the country net of specially protected natural territories (reserves, parks etc.) did not embrace the soil diversity and, consequently, the biological diversity.
Epiphytic yeasts communities have been investigated on various plants belonging to different taxonomic and ecological groups. Species composition of epiphytic yeasts was shown to be on average unspecific and represented by phytobiontic anamorphic basidiomycetous species. The total number of yeasts on plant leaves was shown to be change regularly during a year. Average number of epiphytic yeasts increases during spring and summer and reaches maximum in late autumn. At that the character of yeasts number dynamic depends on ecological peculiarities of plants and on duration of their ontogenesis. Three types of epiphytic yeasts dynamic have been distinguished depending on ecological peculiarities of plants: year-round with autumn-winter increase for gigrophytous and mesophytous plants, year-round without visible changes for xerophytous, and seasonal with terminal increase for annual plants.
The comparative analysis of epiphytic yeast communities has been conducted in two similar but geographically remote biogeocenoses with simultaneous employment of different methods for taxonomic identification of yeasts: traditional on the base of morphological and physiological features and molecular-biological (PCA with unspecific primers, restriction analysis of DNA, rDNA sequencing). Epiphytic communities in these biogeocenoses were found to be very similar on their phenotypic species composition in spite of significant spatial removal. At that different populations of the same species, isolated in similar microhabitats in geographically distant regions, were found to be significantly different in their molecular-biological characteristics. The influence of spatial nearness of epiphytic yeasts communities on the similarity of their taxonomic composition due to reciprocal contamination has been demonstrated.
Plant tissues with reserve functions, in particular cotyledons of some fruits, were found to be inhabited by endophytic yeasts. These data change our insight about forms of life of non-pathogenic saprotrophic epiphytic microorganisms.