Phytomass increase and death are the main processes that are aimed at studying the carbon cycle in ecosystems. Using the experimental data growth and decomposition of plant material obtained on key parts of the bogs of the southern taiga of Western Siberia, an attempt was made to determine the carbon balance in wetland ecosystems. In the center Bakchar’s bog (56˚48.804'N, 82˚51.300'E) on the height of 153 m a.s.l. are the main vegetation communities: pine-dwarf shrub-sphagnum ridge, beak rush-sphagnum and sedge-sphagnum oligotrophic hollows, which form a ridge-hollow complex. At the height of 126 m a.s.l., 6 km from the first key area (56˚51.186'N, 82˚50.836'E) are of common pine-dwar shrub-sphagnum ryam, dwarf shrub-cotton grass-sphagnum and sedge-sphagnum mesotrophic fens. In the 6 wetland ecosystems (raised bog, transitional dwarf shrub-sphagnum and sedge-sphagnum mesotrophic fens, ridges and oligotrophic hollows) was determined biomass stocks and net primary production. Stocks living phytomass in wetland ecosystems Bakchar’s bog high and vary from 860 to 1710 gC/m 2. Production varies on an even larger extent than by ecosystem type, and range (125-790 gC/m 2 per year). The more net primary production, the more loss-decomposition. Formed during the growing season plant material in the first year loses the decomposition from 8 to 27% of the net primary production that is 14 to 106 gC/m 2 depending on the type of ecosystem and the higher production, the faster the rate of decomposition. For further decomposition and transition in the peat remains to 420 gC/m 2 plant material in more productive wetland ecosystems ryams and mesotrophic fens, and 140 gC/m 2 in poor oligotrophic hollows. The remaining amount is further decomposition.