三江源国家公园土壤侵蚀及其分布特征

Soil Erosion and Its Spatial Distribution Characteristics in Three-River-Source National Park

[目的]三江源是“中华水塔”和中国重要生态安全屏障。探讨三江源国家公园土壤侵蚀分布规律,为实施生态保护政策及三江源国家公园水土保持与生态文明建设提供依据。[方法]利用中国土壤流失方程(CSLE)、风力侵蚀模型和冻融侵蚀强度评价模型,采用叠加分析的方法,分析三江源国家公园土壤侵蚀状况及其在不同空间和下垫面的分布特征。[结果] 2020年公园土壤侵蚀面积2.64×10^(4) km^(2),黄河源园区是土壤侵蚀分布最广泛的园区,而长江源园区土壤侵蚀相对严重;70%的水力侵蚀面积分布在地下冰发育带(海拔4 900 m以上),85%的风力侵蚀面积分布在地下冰发育带以下区域(海拔4 900 m以下),不同海拔高度区域土壤侵蚀及其分布差异显著;坡度5°及以下区域风力侵蚀面积比例达60%,是风力侵蚀相对集中分布区;水力侵蚀相对集中分布在8°~25°区域,水力侵蚀面积比例达75%,均是水土流失综合防治的重点区域;草地面积比例近80%,低覆盖、中低覆盖草地土壤侵蚀相对集中分布,沙地、裸土地的土壤侵蚀问题相对严重,值得重点关注。[结论]三江源国家公园水力侵蚀主要分布在海拔4 900 m以上地下冰发育带,8°~35°的中低覆盖以下草地,占水力侵蚀面积的2/3左右;风力侵蚀主要集中分布在4 200~4 900 m,≤5°的中覆盖度以下草地。

[Objective]The Three-River-Source National Park(TRSNP)is considered to be the“water tower of China”,and is an important ecological security barrier in China.The soil erosion distribution law of TRSNP was studied to provide a basis for implementing ecological protection policy,soil and water conservation,and ecological civilization construction in TRSNP.[Methods]Based on the Chinese soil loss equation(CSLE),wind erosion model and freeze-thaw erosion intensity model,the soil erosion status and its distribution characteristics at different space and surface of TRSNP were analyzed by superposition analysis.[Results]In 2020,an area of 2.64×10^(4) km^(2) suffered from soil erosion in TRSNP.Among the three sub-parks,the Yellow-River-Source Park exhibited the most extensive soil erosion,whereas the Yangtze-River-Source Park was subject to severe erosion comparatively.Soil erosion and its spatial distribution varied significantly at different elevations.Water erosion occurred mainly in the area with elevations above 4900 m,which occupied 70%of the land area.However,85%of the wind erosion occurred in zones with elevations less than 4900 m.The wind erosion area with slopes between 0°and 5°accounted for 60%,which is the relatively concentrated distribution area of wind erosion.And three-quarters of water erosion areas were concentrated in regions where the slope ranged from 8°to 25°,all of which require urgent conservation measures.Grassland was the most important land cover in TRSNP,occupying about 80%of the area,with low and medium-low vegetation cover being responsible for significant soil losses.Additionally,sandy land and bare land were prone to high intensity soil erosion,which deserved special attention.[Conclusion]Two-thirds of water erosion areas were primarily located in zones where the elevation was above 4900 m,slope gradients were between 8°and 35°,and grassland cover was below medium-low cover.Wind erosion was primarily located at elevations ranging from 4200 m to 4900 m,slopes were less than 5°,and grassland coverage was below medium-low cover.