Spatial-Temporal Changes in the Critical Vegetation Coverage of Grasslands with Functions of Soil-Water Conservation,Wind-Breaking and Sand-Fixing in the Three-Rivers Headwater Region,China
The Three-Rivers Headwater Region(TRHR)is a crucial ecological barrier in China and its functions of soil-water conservation,wind-breaking and sand-fixing are great significance to the ecological security of China and its neighboring areas.A Critical Vegetation Coverage(CVC)is a key indicator for measurement of the function level of soil-water conservation,wind-breaking and sand-fixing on a regional basis,and it is applicable to quantitative evaluating of ecological level of grasslands in TRHR;unfortunately,there was little information about CVC in TRHR.In this study,Revised Universal Soil Loss Equation(RUSLE)and Revised Wind Erosion Equation(RWEQ)were used to simulate the variation of CVC in TRHR from 1979 to 2018 and then their spatial and temporal pattern were analyzed.(1)In the past 40 years,the CVC for soil-water conservation in TRHR was higher in the southeast and lower in the northwest,with a multi-year average value of 12.21％±1.42％and a growth rate of 0.30％(P＜0.01).(2)The CVC for wind-breaking and sand-fixing was higher in the northwest and lower in the southeast,with a multi-year average value of 39.84％±11.94％and a slight growth trend.(3)The CVC for soil-water conservation & wind-breaking and sand-fixing had a distribution of higher values in the northwest and lower values in the southeast,with a multi-year average value of 45.38％±10.04％and a growth rate of 0.32％(P＜0.05),ranging from 11.73％to 58.56％.In the northwest of TRHR,the CVC for soil-water conservation & wind-breaking and sand-fixing exceeded 50％,while in most parts of the southwest,it did not exceed 40％.(4)It found the CVC for soil-water conservation & wind-breaking and sand-fixing had a decreasing trend in the northeastern areas of the Yangtze River headwater area and the Yellow River headwater area,with a significant decrease in the northeastern Yellow River headwater area(P＜0.01),whereas in the southern Yellow River headwater area as well as the Lancang River headwater area it described a significant increasing trend(P＜0.01).These results would provide a scientific basis for ecological environment protection and multi-objective management in the alpine grasslands of TRHR.
critical vegetation coverecological thresholdecological restorationalpine grasslandThree-Rivers Headwater Region
NETL
NSTL
万方数据
