Background Vegetation is the most active factor in the natural ecosystem and the inhibitory effect of surface vegetation cover on soil erosion has been well known. Existing studies have shown that under certain other conditions (precipitation, soil and topography), vegetation coverage has a significant negative correlation with soil erosion. Therefore, analyzing the dynamic changes of vegetation cover and its driving factors is critical to regional soil and water conservation, governance effectiveness evaluation and land space planning in mountainous areas.

Methods Based on MOD13Q1 data, this paper systematically analyzed the temporal and spatial evolution characteristics of vegetation coverage in Wenshan from 2001 to 2020 using methods such as pixel dichotomy, one-dimensional linear regression equation, coefficient of variation, Hurst index and statistical methods. Spatial analysis was also employed by overlaying vegetation cover change information with land use during the past two decades to reveal the driving forces behind.

Results 1) In the past 20 years, the annual vegetation coverage in the study area showed an upward trend of fluctuation, areas of extremely high vegetation coverage with FVC over 80% increased dramatically, ranging from 3 997.22 km² in 2001 to 15 313.78 km² in 2020. 2) Areas with improved and significantly improved vegetation coverage (84.51%) were more dominant than those areas of degraded and significantly degraded vegetation coverage (6.47%). About 80.98% of the total area was characterized by a stable vegetation coverage change, only 0.50% of the area showed a strong variability in vegetation coverage change, with a scattering distribution. However, the average Hurst index for 71.14% of Wenshan was < 0.5, which indicated that there will be a certain degree of reverse decline for the future vegetation coverage change. 3) Based on overlay analysis, the dynamic change ratios of cultivated land, forest land and artificial surface were 38.14%, 35.01% and 27.67%, respectively, which were the major factors responsible for the vegetation coverage change.

Conclusions The method mentioned in this study provides a reliable estimation, due to the consideration of time series images and multi-perspective analysis, which are potentially transferable to other mountainous areas as a robust approach for rapid assessment of vegetation coverage, as well as soil erosion control efforts. Overall, the status of vegetation coverage, the ecological environment has been continuously improved during the past 20 years, as well as the construction of ecological civilization.