Figure 2 Study workflow.

2.3 Vegetation Surveys

On the same day as the drone flight, a field survey was conducted to provide ground validation of the UAV data and subsequent data processing and classification. In order to maintain the uniformity of species composition, community structure, and habitat, transects were established using stratified sampling. The survey design consisted of three transects, selected based on the characteristics of the underground coal mining faces. Each transect exhibited distinct key features and demonstrated low spatial heterogeneity. Within transects, ten plots were established, comprising four randomly assigned subplots: tree (30m x 30m), shrub (10m x 10m), and herb (1m x 1m) plots including replicates (Figure 3). Vegetation species composition was then identified, and number of individuals, height, and coverage was recorded. Geomorphological features and vegetation communities were located and photographed to aid in identification and validation of the UAV-generated data.