Soil Respiration and Biogenic Carbon Dioxide Sink in the Territory of Russia: An Analytical Review

Studies on the assessment of soil respiration and ecosystem CO2 sink in the territory of Russia are reviewed over the period since the adoption of the United Nations Framework Convention on Climate Change (Rio de Janeiro, 1992). The first estimates of total soil respiration in the entire territory of Russia, made in 1995 to 1998, amount to 3.1 and 4.3 Gt C per growing season and per year, respectively. On average, soil CO2 efflux over the cold season (November–March) accounts for 20–30% of annual efflux. The contribution of heterotrophic respiration (R H ) to the total soil respiration (R S ) may reach 30–70%, depending on ecosystem type. Despite differences in methods used to measure R H , the results obtained by different authors vary within a relatively narrow range, from 2.9 to 3.5 Gt C/year at an uncertainty level of about 20%. The soil cover of Russia (11.7% of the global land area) accounts for 6.3% of global soil CO2 efflux. The data on ecosystem CO2 sink are widely scattered among publications. Estimates of carbon balance differ depending on approaches and methods used to determine its individual components and the level of uncertainty in the results. However, most of them confirm the main conclusion: the territory of Russia with its forests is an absolute CO2 sink with a potential of 200 Mt C/year. This conclusion has been corroborated in the absolute majority of studies performed by Russian and international research teams.