Effects Of Vegetation Restoration On Organic Carbon Pools And Aggregate Stability In Agro-pastorally Transitional Alpine Region

Vegetation is one of important factor to affect the contents of soil organic carbon and aggregate, which increases the input of soil organic carbon and improves soil structure. However,the influence of vegetation restoration on soil organic carbon pools and soil aggregates stability in Agro-pastorally Transitional Alpine Region has not been well understood. This work was designed to investigate the changes in soil organic carbon dynamics and aggregates stability and their relations in cultivated alpine soil induced by Elymus sibiricus plantaion and abandonment, compared with cultivation and therefore we evaluated the influence of vegetation restoration on grassland sustainable development in Agro-pastorally Transitional Alpine Region. The main conclusions as following:1 Compared with cultivation, It was found that total soil organic carbon contents was increased by 19.7～22.4% and 7.3～10.6%, particulate organic carbon contents by 43.0～52.3% and 28.7～59.8%, carbohydrate carbon contents by 13.8～27.9% and 4.94～29.7%, total nitrogen contents by 12.0～20.6% and 5.4～13.7% at depth 0-30 cm in soils under Elymus sibiricus plantaion and abandonment after three years conversion from cultivated soil,mineral carbon contents was increased by 49.0%and 14.4% in 0-10cm depth, and which has not significant effect in 10-30cm depth. This result might indicate that Elymus sibiricus plantation and abandonment are advantageous to the soil organic carbon contents and total nitrogen contents enhancement, which are favorable to the improvement in cultivated alpine soil quality.2 Compared with cultivation, It was found that soil water stable aggregates ration was increased by 45～110% and 45～113%, and mean weight diameter by 11～65% and 28～95% at depth 0-30 cm in soils under Elymus sibiricus plantaion and abandonment after three years conversion from cultivated soil, This result might indicate that Elymus sibiricus plantation and abandonment have important influence on enhancing soil structure stability and improving soil anti-erosion.3 Our research indicated that soil total organic carbon contents and particulate organic carbon contents were all more closed linear relationships to soil water stable aggregates ration and mean weight diameter. But carbohydrate carbon content was also significant linear relationship to soil water stable aggregates ration. This result might indicate that it was closely related between improvement of soil quality and changing of soil organic carbon contents by vegetation restoration, particulate organic carbon and carbohydrate carbon have main function in water aggregates stability, This result further explained Elymus sibiricus plantaion and abandonment resulted in soil particulate organic carbon and carbohydrate carbon contents remarkably increased was the most directly reason of soil aggregate stability improvement.The above research results showed that, in Agro-pastorally Transitional Alpine Region Elymus sibiricus plantaion and abandonment may remarkably increase the soil organic carbon contents, meanwhile which are advantageous to improving soil water stable aggregates stability and increasing soil anti-erosion, thus this has very important meaning that vegetation restoration is advantageous to raising soil quality and improving ecosystem environment in this region.