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分析了青海省三江源区草地生态系统土壤侵蚀的空间差异,以及草地退化与土壤侵蚀的关系,并对该区近30年来土壤侵蚀的动态变化进行描述。结果表明,该区域微度以上土壤侵蚀面积占源区总面积的46.47%,而草地生态系统发生微度以上土壤侵蚀的面积比例达56.04%。源区土壤侵蚀类型是以冻融侵蚀伴随着水力侵蚀或风力侵蚀的复合侵蚀为主,分别占源区土壤侵蚀总面积的41.93%和20.48%,侵蚀程度以轻度为主。源区土壤侵蚀受垂直地带性和区域地貌格局的影响,水力侵蚀、风力侵蚀、冻融复合型侵蚀分别发生在3 200~4 600m、2 800~3 600m和4 400m以上的海拔范围内,以及5~25°、<3°与5~15°的坡度范围内,与坡向关系不大。风力侵蚀和冻融复合型侵蚀的程度随海拔升高而呈增加趋势,而水力侵蚀则呈下降趋势。对20世纪70年代中后期-90年代初、90年代初-2004年两个时段土壤侵蚀的比较发现,20世纪90年代以来三江源区的土壤侵蚀状况在前期加剧的情况下更加恶化,而气候暖干化导致的多年冻土退化和长期超载过牧导致的草地生态系统退化是造成三江源区草地生态系统土壤侵蚀加剧的主要因素。
The spatial differences of soil erosion and the relationship between grassland degradation and soil erosion in the grassland ecosystem in the Three River Source Region of Qinghai Province were analyzed. The dynamic changes of soil erosion in the past 30 years were also described. The results showed that the area of soil erosion above the micro-degree accounted for 46.47% of the total area of the source area, while the area of soil erosion above the micro-level was 56.04% in the grassland ecosystem. The type of soil erosion in the source area is mainly composed of composite erosion with erosion or wind erosion accompanied by freeze-thaw erosion, accounting for 41.93% and 20.48% of the total area of soil erosion in the source area, respectively. The degree of erosion is mainly slight. Soil erosion in the source area is affected by vertical zonation and regional geomorphology. Water erosion, wind erosion and freeze-thaw complex erosion occur within the elevation ranges of 3 200 ~ 4 600m, 2 800 ~ 3 600m and 4 400m respectively, and 5 ~ 25 °, <3 ° and 5 ~ 15 ° slope range, and the relationship between the slope is not. The degree of wind erosion and freeze-thaw compound erosion increased with elevation, but hydraulic erosion showed a downward trend. A comparison of soil erosion between the late 1970s-early 1990s, early 1990s-2004 shows that soil erosion in the Three Rivers Source Region worsened in the earlier period since the 1990s, while climate The degradation of grassland ecosystem caused by the degradation of permafrost caused by warm-drying and long-term over-grazing is the main factor that aggravated the soil erosion in the grassland ecosystem in the Three River Source.