基于MODIS-EVI的四川省2000—2020年植被覆盖度地形分异研究

Research on the Topographic Variability of Vegetation Coverage in Sichuan Province Based on MODIS-EVI from 2000 to 2020

【目的】定量分析四川省2000—2020年的植被覆盖度地形分异特征,以便从宏观上了解区域植被覆盖变化情况。【方法】借助于Google Earth Engine平台,以MODIS-EVI和地形地貌数据为基础,运用变异系数和分布指数结合GIS空间分析技术对四川省2000—2020年的植被覆盖度变化进行分析。【结果】2000—2020年四川省植被覆盖度波动变化以轻度波动类型为主,然后依次为稳定、中度波动和重度波动类型,它们的占比分别为55.28%,25.55%,13.96%和5.21%。在高程小于或等于1 500 m和大于5 500 m,坡度小于或等于15°,坡向为东北坡、东坡、东南坡和南坡,地貌为台地、丘陵、小起伏和中起伏山地区域,植被覆盖度波动变化以稳定类型分布为主;在高程范围为>1 500~2 500 m区域,植被覆盖度波动变化以轻度波动类型分布为主;在高程范围为>2 500~4 500 m,坡向为西南坡、西坡和西北坡,地貌为大起伏山地区域,植被覆盖度波动变化以中度波动类型分布为主;在高程范围为>4 500~5 500 m,坡度大于15°,坡向为平地、北坡,地貌为平原和极大起伏山地区域,植被覆盖度波动变化以重度波动类型分布为主。【结论】2000—2020年四川省植被覆盖度存在不同程度的波动变化,地形地貌空间分布差异明显;研究结果可为四川省后续的生态植被恢复工作提供参考。

[Purposes]Quantitatively analyze the topographic variability of vegetation coverage in Sichuan province from 2000 to 2020, and understand the changes in vegetation coverage from a macro perspective. [Methods]Based on the MODIS-EVIand topography data, it analyzed the variability of vegetation coverage in Sichuan province from 2000 to 2020 by using the Google Earth Engine platform combined with the GIS spatial technology, the coefficient of variation and the distribution index. [Findings]From 2000 to 2020, the fluctuation of vegetation coverage in Sichuan province was dominated by mild fluctuation types, followed by stable, moderate fluctuation and severe fluctuation types, and their proportions were 55.28%, 25.55%, 13.96% and 5.21%, respectively. The types of vegetation stable were mainly distributed in the areas where the elevations were less than or equal to1 500 m and greater than 5 500 m, slopes less than or equal to 15°, northeast aspects, east aspects, southeast aspects, south aspects, terraces, hills, small undulating mountains and moderately undulating mountains. The types of vegetation mild fluctuations were mainly distributed in the areas where the elevations were between1 500 m and 2 500 m. The types of vegetation moderate fluctuations were mainly distributed in the areas where the elevations were between 2 500 m and 4 500 m, southwest aspects, west aspects, northwest aspects and large undulating mountains. The types of vegetation severe fluctuations were mainly distributed in the areas where the elevations were between 4 500 m and 5 500 m, slopes greater than 15°, flat, northern aspects, plains and extremely large undulating mountains. [Conclusions]From 2000 to 2020,the vegetation coverage in Sichuan Province had fluctuated to varying degrees, and the spatial distribution of topography and landforms was significantly different. The research results can provide reference for the follow-up ecological vegetation restoration work in Sichuan province.