Decomposition of plant residues in peat soils of oligotrophic peatlands

The study of the transformation of organic matter is of great importance at present time, due to climate change and the increasing level of human impact on natural ecosystems. In peatlands there is a constant exchange of minerals between plants and peat soils. The rate of decomposition of plant residues and release of these nutrients depend on individual characteristics of the chemical composition of plants and the environment in which these processes occur. Peatlands have a lower, compared with the net primary production, speed of transformation of organic matter of plants, due to which there is a constant accumulation of organic matter in the form of peat. To estimate the rate of peat accumulation and the amount of carbon stored in the form of peat from decomposition of crop residues, we carried out an investigation of the destruction of peat-forming plants (13 species), growing on oligotrophic peatlands of the southern taiga subzone of Western Siberia. The studies revealed that the most intense transformation processes are at an early stage of decomposition, and then the degradation rate decreases. The most resistant to decomposition are sphagnum mosses, except Sph. angustifolium. The least resistant - herbaceous plants: Menyanthes trifoliata, Rubus chamaemorus. Shrubs are characterized by an average rate of decomposition. Thus, the main peat-forming plants, at present, in the studied oligotrophic bogs are sphagnum moss, as also evidenced by botanical composition ofpeat deposits. The dynamics of the removal of carbon from residues peat-forming plants have the same trends as the weight loss during organic matter destruction. Removal of carbon during decomposition of peat-forming plants during the year depending on the type ofplant is from 3% (Sphagnum fuscum) to 72% (Menyanthes trifoliata), and the average for phytocenosis is 33%. In the process of decomposition of plant residues in the first year, as a rule, there is immobilization of nitrogen in many of the studied plants (S. fuscum, S. magellanicum, Vaccinium vitis-idea, Andromeda polifolia, Ledum palustre, Chamaedaphne calyculata, Vaccinium oxycoccus, Rubus chamaemorus). The maximum accumulation of nitrogen is characteristic for S. fuscum (187% of the initial quantity). A comparison of net primary production of the studied plant communities and the rate of destruction showed that the amount of carbon stored in the process of photosynthesis is much higher than the loss of carbon during decomposition of plant residues both for certain species of plants (2-25 times depending on the plant species) and for phytocenosis overall (4—7 times depending on phytocenosis).

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