ИСТИНА

According to estimates (ROSSTAT, 2017), the area of abandoned agricultural land in Russia exceeds 38 million hectares. Analysis of carbon content dynamics during a post-agrogenic succession is important for understanding the rate of natural restoration of soil and vegetation and for an effective decision-making on the post-agrogenic ecosystems (Lyuri et al., 2010). We studied changes in sandy soils of post-agrogenic pine forest ecosystems abandoned at different periods of the XX century in Smolensk Lakeland National Park to assess the soil organic carbon stock dynamics at different stages of recovery. The results showed a maximum value of carbon stocks in the meadow soils (about 3.5 – 5.5. kg/m2) due to the influence of the large amounts of above- and below- ground grass litter entering the soil. The change from meadow to woody vegetation causes a reduction in root deposit input and the formation of a litter horizon on the soil surface. It results in the reduction of organic C stocks in the mineral soil. The minimum of the soil organic carbon stock was observed at the middle-aged (a 50-70-year old) pine forest (about 1.5 – 2.5 kg/m2). The soil organic carbon stock of old-growth primary and secondary pine forests are higher (about 2 – 4.5 kg/m2) due to more intensive litter humification and increasing root phytomass. This study was supported by the Russian Science Foundation (project no. 21-74-20171). 1. ROSSTAT, 2017. Russian Statistical Annual. Moscow. (686 p. (in Russian). 2. Lyuri, D.I., Goryachkin, S.V., Karavaeva, N.A., Denisenko, E.A., Nefedova, T.G., 2010. Dynamics of Agricultural Lands of Russia in XX Century and Postagrogenic Restoration of Vegetation and Soils. Geos, Moscow (420 p. in Russian).