Biological activity of soils in genetic reserves of Northern Ladoga area

Our major task was to study biological activity of the soils in spruce genetic reserves of Northern Ladoga area. The soil survey based on the regional classification revealed 5 types of soils most typical of the sample plots in question. Three pits (organogenic Leptosol, peaty Histosols and podbur) exposed soils over crystalline bedrock. Two pits exposed soils over loamy moraine (raw humus Cambisol and transitional bog peat-gley soil).One of the specific research tasks was to determine the structure and numerical strength of the principal ecotrophic groups of microorganisms in the surveyed soils, and to study functional activity of the microbial community in these soils. Soil samples for the microbial-biochemical analysis were taken by individual genetic horizons from five points on the pit wall throughout the profile. The abundance of heterotrophic soil microorganisms, which take part in the transformation of nitrogen-, carbon-bearing compounds, was determined by inoculation on dense elective culture media following the technique traditionally used in soil microbiology. The species composition of the soil microbial community was determined by the molecular method of GC-MS. Catalase activity was determined gasometrically following Kruglov and Paromenskaya. Having analyzed the resultant data we found out that the numbers of saprotrophic bacteria in the soils ranged from 10 3 to 10 7 CFU/g of soil. The rate and directivity of the organic matter microbial transformation in automorphic soils was higher, and the microbial activity of distribution patterns differs from that in hydromorphic soils. In terms of total microorganism numbers in the upper soil horizon, soils of the automorphic series formed the following upward sequence: typical raw humus Cambisol > medium thickness raw humus podbur > organogenic Leptosol. Catalase activity in the soils in question ranged from 2.7 to 41.0 гпЮ/5 min/g of soil. The index was the highest in the upper horizon of typical raw humus Cambisols, and the lowest - in the mineral horizon of these soils at a depth of 45 cm. Application of the molecular method to the brown soil type yielded biotypes identified as prokaryotes, fungi, yeasts, protozoans, eukaryotes, Planta in horizons A0 and A1. We also found out that in terms of the abundance the dominant biotypes in the microbial community are presented by Caulobacter, Rhodococcus equi. High numerical strength was also demonstrated by Streptomyces-Nocardiopsis, Bacillus sp. The data from this study can be used in ecomicrobiological monitoring of soils in spruce stands, and serve as the basis for working out sanitary and hygienic indicators of soil quality in disturbed ecosystems.