STUDY OF INFLUENCE OF SOIL TYPE, VEGETATION, ALTITUDE AND ORGANIC CARBON CONTENT ON SOIL MICROBIAL ABUNDANCE

Microbiological studies of forest soils are an important field of research due to the role of forest as carbon sinks and the main role of microorganisms in biogeochemical cycle and in the transformation of organic mass. Microbiological monitoring of soils in forest ecosystems is of key importance to achieve accurate and comparable data. This paper examines the interrelationship of soil microbial communities with different environmental characteristics. For the purpose of the study, the influence of soil type, the influence of some soil parameters, tree composition and altitude on microbial abundance were analyzed. Basic soil parameters were evaluated - content of organic carbon and pH in water extract. For the purpose of the study, 20 representative sample plots were laid out in the territory of Vitosha nature park. The sample plots are in Cambisols and Umbrisols. The microbiological abundance of soils was determined. The total microbial number varied from 5.59 to 6.60 CFU log10/g soil mass. Cambisols have a higher microbial abundance. The sample plots with higher microbial abundance are concentrate at altitudes between 1200 m a.s.l. and 1500 m a.s.l. The data were evaluated statistically. Of greatest importance in the study sample plots is altitude, followed by organic carbon content. Sample plots under mix vegetation have greater microbial abundance. Under coniferous vegetation, the participation of micromycetes in the microbial communities clearly stands out.