Analysis of Vegetation Coverage Change in Jiuzhaigou National Nature Reserve Before and After Earthquake Based on RS and GIS

In order to explore the range and degree of vegetation coverage change in Jiuzhaigou National Nature Reserve before and after the earthquake, based on ENVI 5.3 and ArcGIS 10.2 software platform, this study extracted and calculated normalized vegetation index (NDVI) and vegetation coverage (FVC) data by using remote sensing image data before and after the earthquake, and then analyzed the temporal and spatial pattern changes of vegetation coverage in Jiuzhaigou National Nature Reserve before and after the magnitude 7.0 earthquake in 2017. The results showed that: (1) The vegetation coverage of Jiuzhaigou National Nature Reserve decreased significantly after the earthquake, mainly concentrated in the north, middle and southwest of the reserve; (2) The epicenter was located in the core area of the reserve. After the earthquake, the increase of low vegetation coverage in the core area was the largest. (3) The earthquake had a great impact on the vegetation in the area with an altitude of < 4000 m, but had little impact on the vegetation in the area with an altitude of > 4000 m. The earthquake reduced the area of vegetation in the slope range of 25°~35°, and the slope directions were east slope, southeast slope, south slope and southwest slope. The research results will provide some scientific reference for the ecological restoration and reconstruction of Jiuzhaigou Nature Reserve after the earthquake, and help us deeply understand the influence mechanism and change law of the earthquake on the vegetation coverage of different topographic factors.