The Variation Characteristics Research Of Soil Organic Carbon And Its Fractions In Spruce Forest Of Tianshan In Xinjiang

The situation of global climate change is becoming increasingly rigorous, the forest soil carbon pool, such as the largest terrestrial ecosystem carbon pool, plays an irreplaceable role in regulating carbon balance, slow the rising of greenhouse gases concentrations such as carbon dioxide in the atmosphere. And the soil organic carbon is the most important part of soil carbon, its content and mineralization characteristics has become a hot spot in the field of the carbon cycle. Therefore, this study choose Tianshan forest ecosystem positioning station as the research area, and is selected five elevation gradients (1800-2000m,2000-2200m,2200-2400m,2400-2600m,2600-2800m) of the soil as the research object, the content of soil organic carbon, microorganisms and their characteristics were analyzed. At the same time, the process of soil organic carbon mineralization was studied, and the mineralization process of organic carbon was simulated by using single index, the double exponential equation, finally the optimal fitting model had been choosed - the double exponential equation as a means of fitting analysis. Then the soil active carbon, slow carbon and resistant carbon were calculated by double exponential equation fitting, further using analysis of variance analysis methods, such as the research probes into the change characteristics of organic carbon and its components.The results showed that: the organic carbon content of five elevation gradient of spruce forest soil was showed gradually reduce with the increasing of soil depth, apparent surface enrichment phenomenon. The extent of change of organic carbon content between soil was significantly higher with the change of elevation, namely soil organic carbon content change caused by soil depth was higher than the elevation gradient changes of content. The soil organic carbon content of different elevation showed the same change rule of reduced after increased first and then decrease with the spruce forest tree canopy density and tree height, diameter at breast height; Tianshan mountain spruce forest soil microbial carbon content under different elevation gradient almost showed the same change trend with organic carbon content, namely the content of a downward trend with the increase of soil depth,0-40 cm soil microbial carbon content proportion was as high as 61.34%-79.30% of the total profile, also showed the surface enrichment phenomenon. At an altitude of more than 40cm two different soil microbial carbon content between tree showed reduced after increased first and then decrease, the change rule of the five at an altitude of 40cm under the same soil microbial carbon content had no significant difference; Spruce forest in each layer of soil organic carbon mineralization showed that early strength was bigger, but as the reaction, the mineralization rate gradually slow, reaction intensity weaken. Surface soil organic carbon mineralization intensity showed the trend of reducing after increased first and then decrease with altitude; Double exponential equation of soil organic carbon mineralization fitting effect was superior to single exponential equation; Spruce forest Co(soil active carbon), Cs(soil slow carbon)and Cr(soil resistant carbon)content in the soil profile showed vertical variation characteristics of reduced gradually along with the deepness of soil deepen, resistant carbon of spruce forest showed basically the same change trend with corresponding soil profile of the content of organic carbon, microbial carbon content; The Co/SOC, Cs/SOC, and Cr/SOC of spruce forest soil of different altitude, proportion size relations was:resistant carbon >active organic carbon>slow organic carbon, resistant carbon played a major effect role on soil organic carbon, but active organic carbon, slow release carbon had little impact on the soil organic carbon content.