Effect Of Grazing Intensity On Carbon Sequestration Rate And Carbon Density Of Festuca Ovina + Forb Meadow Grassland At The Northern Slope Of Tianshan Mountains

Grassland ecosystem is an integral part of the global ecosystem,which plays an important role in studying global carbon cycle. Grazing is the most common,the simplest and the most economic way which is a way of people to use the grassland.It has an important theoretical value and realistic ecological signif icance which study the carbon sequestration rate and carbon density of meadow grassland at the northern slope of Tianshan mountains combining with the different grazing intensity.The study explores the changes of carbon sequestration and carbon density under different grazing intensity which research object is the north slope of tianshan mountain grass meadow steppe.When the grassland is leisure ranch,the amount of carbon absorption reached a maximum at 10 every month,carbon absorption time is from 9 to 20,the carbon emission time is from 22 to 7.The carbon emission time is the all day when the grassland is heavy grazing.The inf luence degree of grazing intensity on carbon sequestration rate is heavy grazing > moderate grazing > light grazing,the amount of carbon absorption when the grassland is leisure ranch and light grazing is far greater than it when the grassland is moderate grazing and heavy grazing.The grassland which is leisure ranch and light grazing is carbon sink,however when the grassland is moderate grazing and heavy grazing,it is carbon source.Grazing intensity has a great influence on abroveground biomass,the aboveground biomass is leisure ranch > light grazing > moderate grazing > heavy grazing.The effect of grazing intens ity on underground biomass is light grazing > leisure ranch > moderate grazing > heavy grazing in the 0-100 cm soil layer. Vertical distribution of the underground biomass have the same change trend under different grazing intensity,underground biomass decline with the increase of soil depth.Underground biomass mainly distributes in the 0 to 10 cm soil layer,accounting for 70 % of the total underground biomass.With the increase of grazing intensity,the abroveground biomass carbon density show leisure ranch > light grazing > moderate grazing > heavy grazing,root carbon density show light grazing > leisure ranch > moderate grazing > heavy grazing,soil carbon density show leisure ranch > moderate grazing > light grazing > heavy grazing.Soil organic carbon density show different changes with the increase of soil depth, its overall trend is declining.The trend of root and soil carbon density show surface significantly.The grassland which is leisure ranch and light grazing is carbon sink,however w hen the grassland is moderate grazing and heavy grazing,it is carbon source.The grassland carbon density gradually reduce with the increase of grazing intensity.Proper grazing is conducive to the increase of carbon density, light grazing is suitable utilize for the grassland,which is beneficial to the sustainable development of grassland in th is area.