关键词: 土地生态敏感性, 时空演变, 遥感指数, GIS, 武威市

Abstract: We evaluated the effectiveness of the Shiyang River Basin governance project, with Wuwei, a key area of the river basin, as the research area. Based on the remote sensing data and analysis of GIS, with four indices including soil erosion, soil desertification, soil water content and soil salinization, the evaluation system of land ecological sensitivity in Wuwei was established. With the principal component analysis, we analyzed spatial distribution of land ecological sensitivity in 1995, 2000, 2005, 2010, 2015 and 2018 and the temporal and spatial evolution patterns. Results showed that: (1) land ecological sensitivity was generally lower in the southwest and higher in the northeast, with a gradual distribution pattern. Some moderately/intensively sensitive land had been transformed into mildly/slightly sensitive land, resulting in a reduction of the overall sensitivity. (2) Over 50% of the land had a relatively low frequency of sensitivity changes, without largescale highfrequency conversion. The frequency of different land types varied significantly, while the internal distribution was relatively concentrated. (3) More than 90% of land ecological sensitivity change was stable or fluctuating, and in some areas, the pattern was in fluctuating declining or rising. Overall, the restored land area was larger than thedegraded area and the land ecological environment was tending good. (4) The fluctuation range of land ecological sensitivity was from 0 to 1.8, which was unstable. A deteriorating process was recorded from 1995 to 2005 and gradually recovering process from 2005 to 2018, indicating that ecological environment in the Shiyang River Basin had been improved and that the outputs of ecological management were remarkable.

Key words: land ecological sensitivity, spatiotemporal evolution, remote sensing indexes, GIS, Wuwei City.