祁连山综合土壤可蚀性指数与环境因子的关联性

Correlation between Comprehensive Soil Erodibility Index and Environmental Factors in the Qilian Mountains,China

土壤可蚀度是估算土壤侵蚀量和评价水土保持功能的关键参数。鉴于国家级水土保持重点预防区——祁连山区的土壤可蚀度研究仍处于碎片化状态,本文以水土保持区划为基础,综合考虑水力和风力侵蚀因子,运用空间分析和地理探测器方法,探究祁连山区综合土壤可蚀性指数(Comprehensive Soil Erodibility Index,CSEI)分布特征及其驱动因子。结果表明:(1)祁连山区域CSEI值为0.16~0.54,中值区(0.20~0.40)占地最大,大多位于研究区东部和中北部,少数位于西部。(2)坡度、年降水量和NDVI对CSEI空间分异影响显著。(3)双驱动因子对CSEI的解释力均高于单因子,呈非线性或双因子增强,各区驱动因子差异显著,陇中丘陵沟壑蓄水保土区(Ⅰ区)为年均风速∩NDVI(q=0.95),河西走廊农田防护防沙区(Ⅱ区)和祁连山山地水源涵养保土区(Ⅲ区)为年降水量∩NDVI(q=0.73和0.63),柴达木盆地农田防护防沙区(Ⅳ区)为土地利用∩年均温度(q=0.37),青海湖高原山地生态维护保土区(Ⅴ区)为土地利用∩NDVI(q=0.65),柴达木盆地农田防护防沙区(Ⅵ区)为年降水量∩年均风速(q=0.17)。综合分析得出,祁连山西部地区降水少、风速强、土壤可蚀度较高;东部地区降水量相对较多,植被覆盖度高,土壤可蚀度低。研究结果可为祁连山区开展山水林田湖草沙生态保护工程、因地制宜制定修复政策提供理论依据。

The Qilian Mountains area is a national key conservation and prevention zone for soil-water loss in China.Soil erodibility index is a key parameter for estimating soil erosion and evaluating soil-water conservation benefits,but the specific knowledge of soil erodibility in the Qilian Mountains area was in a fragmented state,far from application.In this study,it explored the distribution characteristics of Comprehensive Soil Erodibility Index(CSEI)in the Qilian Mountains area and its driving factors using spatial analysis and Geodetector methods based on the National Water and Soil Conservation Zoning(NWSCZ)issued in 2012 by Ministry of Water Resources of China.It found that(1)in the Qilian Mountains area,CSEI value ranged from 0.16 to 0.54,with an average of 0.38.The areas with low-value CSEI(0 to 0.20)occupied the smallest lands,primarily in the southeast of the Qinghai Lake Plateau mountain ecological conservation area(ZoneⅤ).The median-value areas(0.20 to 0.40)covered the largest area,mainly in the Longzhong Hills Gully water storage conservation area(Zone I)and in the Qingdong-Gannan Hills Gully water storage conservation area(ZoneⅣ),the farmland protection and sand prevention area in Hexi Corridor(ZoneⅡ),the mountain water conservation and soil conservation area in the Qilian Mountains(ZoneⅢ),and the east of ZoneⅤ.The high-value area(0.40 to 0.60)covered a large area,mainly in the west of ZoneⅡ,Ⅲ,Ⅴand the farmland protection and sand prevention area of the Qaidam Basin(ZoneⅥ).(2)Slope,annual precipitation and normalized vegetation index(NDVI)had a significant impact on CSEI spatial differentiation.(3)NDVI expressed strong explanatory power concerning the spatial distribution of CSEI and was the primary driving factor for 89.38%area of the study area.There was a considerable difference in the types of dual driving factors.The driving factor was the average annual wind speed∩NDVI(q=0.95)in ZoneⅠ,the annual precipitation∩NDVI(q=0.73 and 0.63)in ZoneⅡand ZoneⅢ,the land use∩average annual temperature(q=0.37)in ZoneⅣ,the land use∩NDVI in ZoneⅤ(q=0.65),and the annual precipitation∩average annual wind speed(q=0.17)in ZoneⅥ.According to comprehensive analysis,the western Qilian Mountains has less precipitation,strong wind speed and higher soil erodibility.In the eastern region,precipitation is relatively high,vegetation coverage is high,and soil erodibility is low.The research can provide a theoretical basis for implementing of ecological protection projects in the Qilian Mountains,and formulating of policy-making.