Evolution and degradation mechanism of surface vegetation coverage in typical ecologically fragile mining areas in western China

The western mining area with fragile ecological background has become the main production area of coal re⁃ sources in China， and the ecological environment of the mining areas has been degraded under the influence of mining，the most obvious impact is on vegetation. In order to reveal the changes of surface vegetation in the mining disturbance areas，the Zaoquan coal mine was used as the target area，the 10 views of continuous SentineL-1A radar im⁃ age data and 93 views of SentineL-2A optical data were selected. Based on Small Baseline Subset InSAR (SBAS-In⁃ SAR) technology，combined with one⁃dimensional linear regression analysis and correlation coefficients，the surface subsidence characteristics during mining were studied，the NDVI time⁃series evolution characteristics of vegetation in the subsidence area and non⁃subsidence area of the working face were analyzed.Also，the time⁃series evolution trend of vegetation cover in the mining area under mining disturbance was assessed，and the degradation mechanism of min⁃ ing⁃damaged vegetation was analyzed. The results show that the surface vegetation NDVI of the Zaoquan mining area from 2014 to 2021 showed a trend of physical cycle，and the overall vegetation cover of the mining area was improved The surface vegetation began to degrade in the year of mining，the degradation degree was low，and the degradation was most obvious in 2 - 3 years after mining， and then slowly recovered. In general， the vegetation cover has gone through the process of slight degradation，significant degradation and gradual recovery. Soil organic content and soil moisture content are important factors affecting the development of vegetation in the mining areas. The changes in surface soil physical and chemical properties such as organic matter，total nitrogen and total phosphorus caused by sur⁃ face subsidence and fracture development in the mining disturbed areas，as well as the decline of groundwater level un⁃ der the influence of mining are important causes of vegetation degradation at the surface of working face. Temperature and rainfall also have an important influence on the development status of surface vegetation in mining areas. The stud⁃ y results provide theoretical and data support for the scientific diagnosis of the growth of mining⁃damaged vegetation in the ecologically fragile mining areas in the western China and the determination of timing for vegetation restoration in the mining areas.