Analysis of the Microbiological Characteristics of Soils fromtheTerritory of Vitosha Nature Park, According to the Differencesinthe Environmental Conditions

An analysis of the microbiological status of 13 soil profiles from the territory of Vitosha Nature Park was carried out. Eight of the studied soils were defined as Dystric Cambisols (Brown Forest soils), and the other five as Umbrisols (Mountain Meadow soils). In order to assess the biogenicity and the prevailing processes of transformation of soil organic matter, the total microbial number was determined, as well as the percentage distribution of the main microbiological groups (spore-forming bacteria, non-spore-forming bacteria, actinomycetes and micromycetes) of the A horizon of the studied soils. The highest microbial abundance was observed in the altitude range from 1000 m a.s.l. up to 1600 m a.s.l. In higher altitudes there was a decrease in the total microbial number. At an altitude of over 2000 meters, soil microorganisms are strongly suppressed. According to the data received in the process of the study it has been found that at such altitudes, higher levels of organic carbon and total nitrogen do not result in greater microbial abundance. Altitude dynamics affects the values of the total microbial number, but no relationship has been established with the distribution of microbial groups. The results show a higher microbial abundance in the tested areas under deciduous vegetation compared to the ones under coniferous and grass vegetation. It was found that the lower pH values cause a greater abundance of the micromycete group.