Specific Features of Organic Matter and Biological Properties of Peats in Forest Swamps and Their Changes in the Process of Functioning

AbstractWhen studying the carbon cycle in the biosphere, special attention is paid in Russia to the transformation of organic matter in the surface layer of supergene zone. The group composition of the organic matter (OM) in peats of different genesis in the taiga zone of Western Siberia is studied. Our data show that it is important to take into account the botanical composition of peat that make up natural and reclaimed forest swamps, well as their spatial heterogeneity, which is a necessary component when estimating the carbon stocks in peat soils of forest ecosystems within the national monitoring system for carbon pools and greenhouse gas fluxes. The experiments on peat OM transformation demonstrate that its efficiency is determined by its botanical composition. According to the rate of OM decomposition, the oligotrophic peats form a sequence: sphagnum-hollow > complex > fuscum > scheuchzeria-sphagnum > cotton grass-sphagnum > scheuchzeria > cotton grass peats and eutrophic peats: hypnum > sedge > sedge-hypnum > menyanthes > woody > wood-sedge peats. According to two-year field experiments on the transformation rate and direction of the OM of peat-forming plants, the component and chemical compositions of their OM significantly changes but in an individual manner for each plant. The content of aromatic polyconjugated systems and carboxyl groups increases, while the amount of carbohydrate fragments decreases. A 60 years long forest amelioration influences the transformation of peat OM. The degree of grass and sedge peat species in the process of amelioration increases by 5% in the 75-cm layer; the content of bitumens decreases, whereas the contents of easily hydrolyzable substances, humic acids, and lignin, increases. The microbiomes and enzymes of the peats in forest swamps of Western Siberian taiga are characterized. Our results confirm the hypothesis by V.E. Rakovsky that the differences in the species composition of peat-forming plants manifest themselves in the chemical and biological characteristics of peat.