Research on dynamic monitoring of vegetation restoration in typical high cold sand areas of northwest Sichuan
In recent decades,land degradation and desertification have threatened the grassland ecological environment and people's production and life in the northwest of Sichuan.To obtain and quantitatively analyze the dynamics and trends of vegetation restoration in sand area management,and explore the mechanisms of ecological restoration changes in typical sand areas.Based on the 1984,2000 and 2021 long time series remote sensing images of the typical sand area in Wache Town,Hongyuan County,supported by ENVI 5.3 and ArcGIS 10.2,the vegetation coverage(FVC)was extracted by NDVI and spectral mixture analysis(NDVI-SWA),and the vegetation restoration and change characteristics of the typical alpine sand area in northwest Sichuan were analyzed by land dynamics Spatial analysis model and Transition matrix.The research showed that:(1)the vegetation coverage level structure is mainly characterized by high vegetation coverage,accounting for over 50%of the study area,and there were significant spatial differences among different vegetation coverage types;(2)The vegetation coverage in the research area was the worst in 1984,and the best in 2021,with moderate and below vegetation coverage accounting for only 4.71%of the area.From 1984 to 2021,the most significant change was in vegetation coverage below moderate levels,with a trend of first increasing and then decreasing in proportion.Relatively speaking,medium to high and high vegetation coverage remained in a relatively stable state of change.(3)In the analysis of FVC stochastic matrix at all levels,the specific transformation direction was relatively consistent,mainly towards the direction of high vegetation coverage,manifested as:transformation from mid high level to high levels,and convert from bottom level to mid bottom and mid level.
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