by Irina KURGANOVA, Dr. Sc. (Biol.), Valery KUDEYAROV, RAS Corresponding Member, Institute of Physico-Chemical and Biological Problems of Soil Science (Pushchino, Moscow Region) In the opinion of most experts, global climate warming in the latter half of the 20th century is caused by the higher concentration of CO2 in the atmosphere. Yet, estimates of the global carbon balance show that the land ecosystems "immobilize" for a time this chemical element sequestering 2.1-2.5 Gt of carbon dioxide per year. Besides, the vast Russian forests, meadows and swamps take the lead in this process. Thereby our country, having a territory above 1/9 of the Earth's surface, accounts for at least 1/5 of the total "budget" of carbon, the basic "life element", which plays a special role in a global biogeochemical cycles. стр. 25 Organic carbon has changed the Earth's surface mantles and provided stability of its carbon-oxygen system during global evolution. Due to complex processes, this "life element" passes from some "pools" into others. Most of all it is present in the litho-sphere and the World Ocean, 12-106 and 37-39-103 Gt C (1 Gt = 1015 g) respectively; its large reserves are concentrated in the organic substance of the soil cover, including peat deposits, and in the land vegetation biomass, 1500-1700 and 500-600 Gt C respectively. Although the two latter figures are too conservative, it is just the land ecosystems that exercise a dominant influence on CO2 natural fluxes and CO2 concentration in the atmosphere. The biogeochemical carbon cycle has not been a closed process--this is one of its distinguishing features. For example, CO2 drops out of the global carbon cycle and enters different "traps"; at the current stage of biosphere evolution it is in the form of peat accumulation and carbon fixation in stable fractions of the soil organic substance. For hundreds and thousands of years it has been preserved in humus, and with its microbiological decom ... Читать далее