ИСТИНА

Abandoning of agricultural lands began in some regions of Russia since the end of XIX century. Our calculation shows, that the total area of abandoned lands since that time (1897-2007) in Russia is approximately 71 mln ha. The process of the self-restoration of natural post-agrogenic ecosystems is very active on almost 65 mln ha of them (fallows) [1, 2, 3]. The carbon sequestration was investigated in Middle and Southern taiga (chronosequences of PAE from 2 to 170-200 years old), hardwood (from 3 to 120 years old), in forest-steppe and steppe zones (from 1 to 50-60 years old) [3,4]. In PAE of forest zones soil organic carbon (SOC) stores decrease after beginning of self-restoration (from 5.3 to 3.2 kg/sq.m in Middle Taiga, from 6.8 to 4.8 in Southern Taiga, from 8.8 to 4.7 in Hardwood (oak) forests) in first 30-50 years. SOC stores begin to grow after 30-50 years and they reach parameters of natural soils at the age of ca 200 years because of litter horizons development. On the other hand, the total ecosystem carbon store (TEC = SOC+ C in plant canopy) in first 20 years of self-restoration decrease because of falling of SOC, and then it begin to increase due to rise of carbon storage in canopy layer. Thus, during ca 200 years the self-restoration of PAE in boreal forests the TEC increase from 5.3 to 15.6 kg/sq.m (in Middle Taiga), from 6.8 to 20.7 in Southern Taiga and from 8.8 to 46.9 in Hardwood forests. Soils of steppe ecosystem in forest-steppe zone restore their parameters in the shortest period – 30-40 years and in 65 years of self-restoration SOC increase from 17.7 to 24.2 kg/sq.m. However, SOC stores of post-agrogenic chernozem do not reach the stores of virgin ones (26.7 kg/sq.m). In dry steppe zone after 30-50 years of self-restoration the SOC increase from 1.9 to 3.3 kg/sq.m, which is less than in virgin soil (4.0 kg/sq.m). Thus, we know the area of different-aged PAE in different ecoregions and their annual carbon sequestration. On this base we can calculate total annual carbon sequestration by all Russian PAE. They accumulate about 64 million tons of carbon annually (first of all in southern taiga – 34 mln tons), which is about 20% of the total current industrial emission of carbon in Russia.