剑阁县植被覆盖度时空变化及地形分异研究

Temporal and Spatial Changes of Vegetation Coverage and Topographic Differentiation in Jiange County

基于1986、1995、2011和2019年4期Landsat TM/OLI遥感数据,以四川省剑阁县为研究区域,利用归一化植被指数和像元二分模型,结合DEM高程数据,分析该地区在经历长江防护林建设、天然林资源保护工程和退耕还林等生态工程过后植被覆盖的变化情况及其地形分异特征。研究结果显示:(1)经过诸多生态工程的改善,剑阁县的植被变化情况较好,以高植被覆盖度和中高植被覆盖度为主,高植被覆盖度所占比例持续增加;(2)通过差值法分析,研究区域内植被变化以稳定和改善为主,在1986—2019年的年际变化中,除低植被覆盖度外,各等级植被覆盖度大多向高植被覆盖度转变;(3)与地形因子结合分析,植被改善区域主要发生在海拔500~700 m、陡坡地和半阳坡等地带,退化主要发生在海拔500~600 m、斜坡地和阳坡等地带,改善面积均大于退化面积。

Based on four Landsat TM/OLI remote sensing data in 1986,1995,2011 and 2019,this paper uses the the normalized difference vegetation index and dimidiate pixel model, combined with DEM elevation data, to analyze the changes of vegetation cover and its topographic differentiation characteristics in Jiange County, Sichuan Province after the ecological projects of Yangtze River shelterbelt construction, Natural Forest Protection Project and the Grain for Green project.The results show that:(1)After the improvement of many ecological projects, the vegetation change situation in Jiange County is relatively good, mainly with high and medium-high vegetation coverage, and the proportion of high vegetation coverage continues to increase;(2)Through the analysis of the difference method, the vegetation change in the study area is mainly stable and improved.In the interannual change from 1986 to 2019,except for the low vegetation coverage, the vegetation coverage of all levels mostly changes to the high vegetation coverage;(3)Combined with the analysis of terrain factors, the improvement of vegetation mainly occurred in 500~700 m, steep slope and semi-sunny slope, while the degradation mainly occurred in 500~600 m, slope and sunny slope, and the improvement area was larger than the degradation area.