Maria Alexandrovna Chepurnova

The response of biological activity and the content of labile forms of biogenic elements in peats of different genesis to variation in their moisture content was studied under laboratory conditions. Samples of peat soils of the northern and southern taiga (Tyumen and Moscow regions) were used in this work. A series of manipulation experiments were conducted in which the dynamics of such indicators as basal respiration (BR), microbial biomass carbon, labile carbon and nitrogen content were estimated for different peat types at different moisture levels. The effect of the experiment duration and type on the dynamics of peat properties was also assessed. It was found that all the studied peat samples are characterized by a wide range of moisture content, at which the maximum of biological activity is observed. In general, it is in the range from 20–30% to 80–90% of water–holding capacity (WHC). In this range, no significant relationship is observed between moisture content and BR. In most experiments, a reliable decrease in biological activity was observed only in the "extreme" humidity ranges - less than 20% and more than 90% WHC. It is shown that the nature of the response to moistening is individual, determined by the properties of the sample and depends little on the type of sample preparation. In experiments and model calculations, it is proposed to use the obtained sensitivity coefficient to moisture — W₂₀, which is 1.0‒1.2 in the range of 40‒80% WHC for peat samples of different genesis. Long-term variants of incubation experiments showed a more pronounced response to overmoistening and a reliable decrease in biological activity at high humidity values (more than 80% WHC). This may indicate their better applicability for solving problems of modeling the behavior of ecosystems in the event of a change in the hydrological situation.