Alexandrova Alina Vitalievna

For the first time, a comprehensive study of the biological activity of microbial communities in protected tropical ecosystems of Vietnam has been conducted using the example of four types of substrates: mineral soils and associated plant litter, rhizospheric soil, and specific soil-like formations —“suspended” soils in baskets of epiphytic ferns. It is shown that suspended soils and plant litter are characterized by 3‒5 times higher microbial biomass (up to 1.44 mg•g⁻1), as well as significantly more intensive processes of carbon dioxide emission, nitrogen fixation and denitrification compared with mineral soil horizons. The revealed high biological activity of these substrates correlates with an extremely high content of organic carbon (up to 51.4%) and less acidic pH values. For the first time, methane emissions were quantified for this territory, showing maximum values in the upper soil layer (up to 173 ng CH4•g‒1•day–1) and a negative correlation with altitude (p=0.0001). The data obtained make it possible to identify plant litter and epiphytic “suspended” soils as key loci of biogeochemical cycles of nitrogen and carbon in the tropical forests of Vietnam.