Characteristics Of Soil Organic Carbon And Its Mineralization Components Under The Fir Forest In The Altai Moutain Area, Xinjiang

In recent years, a series of problems caused by the climate change has aroused increasing concern, forest soils,as the largest terrestrial ecosystem carbon stocks, not only to maintain and regulate the carbon balance of the ecosystem, but also to slow the rise of atmospheric carbon dioxide and other greenhouse gas concentrations to a great extent, In the research and development process of soil carbon, the study of soil organic carbon has become a hot spot in the field of research in terrestrial ecosystem carbon cycle in recent years. Therefore, this study selected Altai Burqin county forestry protection station as the study area, four elevation gradient (1300-1500 m,1500-1700 m,1700-1900 m and 1900-2100 m) were selected respectively, analyzing the characteristic of its forests soil organic carbon content, while using single index and double exponential equation exponential equation to fit the soil organic carbon mineralization process, final, preferably choosing the double exponential equation as a means of soil organic carbon fitting research. At the same time, soil carbon fractions (active organic carbon, slow release organic carbon and resistant organic carbon) were further studied, analyze and compare organic carbon mineralization rate and mineralization ratio.Results show that the fir forest soil organic carbon content increased with increasing soil depth in each elevation gradient and surface enrichment phenomenon is obvious. With increasing elevation gradient, soil organic carbon of the same layer showed an increase after the first reduction, in addition, whole soil profile in 1900-2100m showed a relatively strong organic carbon accumulation feature, soil carbon mineralization cumulative release amount of each layer has a rapid growth at the beginning, as the reaction proceeds, the mineralization is gradually intense, in the late mineralization rate slows, reaction intensity is weakened; double exponential equation can better simulate the process of soil organic carbon mineralization, the fitting effect is better than the single index; fir forest soil active carbon, slow release carbon and resistant carbon content in the vertical section gradually decreased with soil depth increase, which the characteristics of soil resistant organic carbon content and the change of soil organic carbon content are similar, but the elevation gradient changes did not result in the obvious change of soil resistant organic carbon content, the proportion of soil active organic carbon,slow release organic carbon and resistant organic carbon in total organic carbon is:Cr/So/Co/SOC>Ss/SOC, soil resistant organic carbon account for much of soli organic carbon, which has the greatest impact on soil organic carbon, while active and slow release component have less effect on the organic carbon content; with the increase of altitude, the forest type is changed from the brich-larch-fir coniferous and broad-leaved mixed forest (1700m below) to the larch and fir coniferous mixed forest (1700m above), soil organic carbon mineralization rate and mineralization ratio present a downward trend, of which coniferous and broad-leaved mixed forest(1300-1700m) soil organic carbon mineralization rate and mineralization rate were significantly higher than that of fir coniferous mixed forest(1700-2100m) soil (p<0.05), the change of forest type lead to changes in forests litter amount and type, degree of decomposition changes, shows various mineralization characteristics.