Nonlinear Responses of Vegetation and Soil Properties to Rock Desertification Gradients in Qingzhen, China

Karst rock desertification is an extreme form of land degradation that poses a serious threat to regional ecological security and sustainable development in Southwest China. Understanding the response patterns of plant communities and soil properties along desertification gradients is critical for developing effective ecological restoration strategies. This study focused on Qingzhen City, Guizhou Province, a representative karst desertification region. Using remote sensing to classify rock desertification intensity, together with systematic vegetation surveys and soil sampling, we investigated variation patterns in ecological parameters along the degradation gradient. The results revealed three key patterns. First, rock desertification was widespread across Qingzhen and exhibited pronounced spatial differentiation. Second, as desertification intensified, vegetation community structure became progressively simplified, transitioning from forests to shrublands. Biomass and vegetation cover declined from 77.25 kg/m 2 and 83% to 0.62 kg/m 2 and 15%, respectively. Notably, species diversity exhibited a bell-shaped relationship with desertification intensity, peaking at the potential desertification stage before declining under increasing environmental stress. Third, soil physicochemical properties showed complex nonlinear responses along the desertification gradient. Soil bulk density decreased, and pH increased with increasing desertification intensity, while volumetric water content fluctuated across stages. Soil total carbon and total nitrogen exhibited temporary enrichment during the light-to-moderate desertification stages, likely due to shifts in litter quality. Overall, these findings demonstrate that both plant communities and soil properties respond nonlinearly to rock desertification gradients. Together, the results enhance the understanding of the ecological processes underlying karst rock desertification and support the development of targeted regional restoration strategies.