基于RUE的不同草地类生态评价研究——以河西走廊为例

选择降水利用效率（RUE）作为评价指标,对河西走廊代表性草地类--温性荒漠、高寒草甸、温性草原进行生态评价研究。通过植被指数提取、降水Co-Kriging插值、图层叠加,得到河西走廊区域2006-2010年的RUE(NDVI)、RUE(PVI)、RUE(TSAVI)数据,并与地上生物量进行相关分析,筛选出适合不同草地类的RUE作为该区域生态评价的指标。结果表明：1）温性荒漠区RUE(PVI)与草地生物量风干重正相关性最高（R²=0.879）,高寒草甸区RUE(NDVI)与草地生物量风干重的正相关性最高（R²=0.876）,温性草原区RUE(TSAVI)与草地生物量风干重的正相关性最高（R²=0.895）。2）温性荒漠区、温性草原区生态均处于退化过程,高寒草甸区处于恢复过程。研究认为选择合适的RUE值可作为不同草地类生态评价指标,并具有理论的可行性和实践的可靠性。

The Ecological Assessment of Different Rangeland Types Based on Rainfall Use Efficiency in Hexi Corridor Area

Using rainfall use efficiency (RUE) as index, we carried out the ecological assessment of typical rangeland types in Hexi Corridor, including temperate desert, alpine meadow and temperate rangeland. By extracting vegetation index, interpreting rainfall with Co-Kriging method and overlying multiple maps, we obtained RUE(NDVI), RUE(PVI) and RUE(TSAVI) in Hexi Corridor. By crrelation analysis between different RUEs and aboveground biomass, suitable RUE for each type of rangeland is selected as index to evaluate the ecological process. The result showed that: 1) The correlation between RUE(PVI) and aboveground biomass is the highest in temperate desert, correlation coefficient being 0.879. The correlation between RUE(NDVI) and aboveground biomass is the highest in alpine meadow, correlation coefficient being 0.876. The correlation between RUE(TSAVI) and aboveground biomass is the highest in temperate rangeland, correlation coefficient being 0.895. 2) The temperate desert is in ecological degraded process, since RUE(PVI) in the range of -11.291--2.000, -1.999-0.000 and 2.001-6.000 is in increasing trend and RUE(PVI) in the range of 0.001-2.000 and 6.001-43.918 is in decreasing trend. The temperate rangeland is also in ecological degraded process, since RUE(TSAVI) in the range of -3.2×10^-3-0.8×10^-3 and 1.4×10^-3-2.4×10^-3 is in increasing trend and RUE(TSAVI) in the range of 0.8×10^-3-1.4×10^-3 and 2.4×10^-3-3.4×10^-3 is in decreasing trend. On opposite, alpine meadow is in ecological recovery process, since RUE(NDVI) in the range of 18.001-36.000 is in decreasing trend and RUE(NDVI) in the range of -6.765-6.000, 6.001-10.000 and 10.001-18.000 is in increasing trend. We believe that selecting appropriate RUE for different type of rangeland as the assessment index is feasible and reliable in theory and practice.