三江源植被保持土壤能力的时空变化

为深入了解三江源区植被保持土壤的能力,以RS和GIS为技术支撑,在对三江源区植被覆盖度动态变化特征分析的基础上,利用SL190—2007《土壤侵蚀分类分级标准》推荐的中国土壤侵蚀模型CSLE(Chinese soil loss equation)估算了2000—2010年三江源区植被的土壤保持能力,并分析其时空动态变化特征. 结果表明:①2000—2010年三江源区年均植被覆盖度为43%~50%；植被平均土壤保持量为849~955 t/km2,并且空间差异很大,总体上呈自西北向东南增加的空间分布格局. ②2000—2010年植被的土壤保持能力呈逐渐增加趋势,其中2000—2005年各流域的土壤保持能力平均增加了约29 t/km2,并以大夏河与洮河流域土壤保持能力的增幅(约700 t/km2)最大,其次为玛曲至龙羊峡(约300 t/km2),羌塘高原区植被的土壤保持能力增幅(仅2.08 t/km2)最小；2005—2010年各流域的土壤保持能力呈现轻微增长,平均增加了约9 t/km2,其中增幅较大的是柴达木盆地东和直门达至石鼓流域(约16 t/km2),增幅最小的是羌塘高原区(仅3.90 t/km2). ③三江源植被土壤保持能力随植被覆盖度的增加呈非线性增长,可通过指数或幂函数形式表达. 研究显示,增加植被覆盖度有助于提高三江源区的土壤保持能力、控制区域土壤侵蚀. 

Spatial and Temporal Variation of Soil Conservation Capability of Vegetation in Three-River Headwaters Region

Abstract: Based on analysis of the dynamic variation of vegetation coverage during 2000-2010 in the Three-River Headwaters Region, the soil conservation capability of vegetation (SCCV) in this region was quantitatively estimated using Chinese soil loss equation (CSLE), and its spatial and temporal variations were analyzed using RS and GIS technologies. From 2000 to 2010, the annual vegetation coverage of this region was between 43% and 50%, and the annual SCCV was estimated between 849-955 t/km². The SCCV in this region showed a very large spatial difference, with an increasing trend from the northwest to the southeast. From 2000 to 2005, the regional average SCCV increased by an average rate of 29 t/km², and the SCCV in the Daxia and Taohe Watersheds showed the largest increase (about 700 t/km²), followed by the areas from Maqu to Longyang Gorge (about 300 t/km²), while Changtang Plateau showed the smallest increase (2.08 t/km²). During 2005-2010, the regional average SCCV slightly increased by an average rate of 9 t/km², and a significant increase of SCCV occurred in areas of eastern Qaidam Basin, Zhimenda to Shigu watersheds (about 16 t/km²), while the smallest increase was found in Changtang Plateau (3.90 t/km²). The SCCA in the Three-River Headwaters Region increased non-linearly with vegetation coverage, which was expressed by exponential and power functions. The power function more significantly expressed the correlation between the SCCA and vegetation coverage. Hence, enhancing the vegetation protection and increasing the vegetation coverage are of significant importance to improve the soil conservation capability and control soil erosion in the Three-Rive Headwaters Region.