Ecological stability evaluation of revegetation community on open-pit coal mine dump slopes

To reveal the dynamic characteristics and change patterns of revegetation community stability on the slopes of open-pit coal mine dump, four dumps from the Beidian Shengli open-pit coal mine in Inner Mongolia was selected as the research object. Eight indicators, including the Shannon-Wiener diversity index, Margalef richness index, Pielou evenness index, Simpson dominance index, vegetation coverage, vegetation height, and aboveground and underground biomass, were chosen. A comprehensive evaluation system was employed to assess the stability of revegetation communities on the south and north slopes of the inner dump,which is in the process of artificial revegetation, as well as YANBANG dump, south dump, and the north dump, which have been in the process of restoration periods of 4a, 5a, and 8a. The assessment included the southern slope, northern slope, and embankment slopes to the south, north, and along the embankment. The relationships between stability factors and environmental factors were analyzed to explore the influencing factors on slope community stability. The results indicate: ① With the increase of recovery years, the overall stability of revegetation community on the slopes shows a steady upward trend, but compared to the background values, its comprehensive assessment index is in a relatively unstable state. ② With the increase of recovery years, community stability on dump slopes shifts from being structure-stability-dominated to function-stability-dominated. In the early stages of recovery, influenced by artificial intervention, species diversity increases and structural stability is high. Over time, structural stability fluctuates and declines, while functional stability increases. Rapid growth of underground biomass and biomass transfer underground gradually form a stable community structure unique to the mining area. ③ From the perspective of slope aspect, with the increase of recovery years, community stability on slopes gradually changes from south slope being superior to north slope to north slope being superior to south slope. ④ The structural stability of the south slope exhibits a higher correlation with environmental factors, while the functional stability of the north slope shows a stronger association with environmental factors. This suggests that communities on different directions employ distinct response strategies to adapt to environmental changes. The abundance of organic matter and total nitrogen content positively influences the functional stability of the community on the slope adjacent to the soil-disposal site.