Potential photosynthetic sink of Carbon in coniferous forests of Irkutsk region for the season 1995–2006 and separately for the arid season of 2003 and optimum season of 2004 is counted. The values of seasonal photosynthesis productivity and biomass increment of miscellaneous coniferous species change up to 5 times depending on conditions of a vegetation season. The maps of a photosynthetic sink of Carbon in forest of three coniferous for the analized seasons are created. The maps show variability of seasonal photosynthesis productivity and year potential sink of Carbon depending on vegetation season conditions and species a coniferous tree.