Long-term Successional Dynamics of Naturally Restoring Vegetation Communities on Karst Rocky Desertification Slopes in the Central Guizhou Plateau

Based on vegetation survey data collected in 2012, 2015, 2020, and 2025 from seven long-term permanent plots established at the karst ecosystem observation research station in Puding, this study investigates the long-term successional dynamics of community vertical layers across different vegetation successional stages during the recovery of karst rocky desertification slopes. We analyzed the dynamic changes in species importance values, Shannon-Wiener diversity, and aboveground biomass (AGB) across tree, shrub, and herb layers. The results indicate that from 2012 to 2025, community AGB increased continuously, with a growing concentration in the tree layer. Specifically, AGB in the tree layer of shrubland increased from 2.05 to 36.89 t/hm², while that of the secondary forest rose from 13.04 to 79.31 t/hm². In the near-climax secondary forest, the tree layer AGB grew from 92.49 to 128.10 t/hm², maintaining a high level and accounting for a stable proportion of over 99%. The Shannon-Wiener diversity index showed no significant variation across different years (p>0.05); however, the successional characteristics differed markedly among the years. Specifically, shrubland and secondary forest exhibited increasing diversity in the tree layer but fluctuating declines in the shrub and herb layers. In contrast, tree layer diversity in the near-climax secondary forest remained stable, while the shrub and herb layers showed upward fluctuations. The dominant species composition shifted from frequent replacement in early stages to relative stability in later stages, with the tree layer showing the highest stability and the herb layer displaying the strongest temporal fluctuations.