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Karst rocky desertification (KRD) is a severe global environmental challenge that profoundly alters ecosystem structure and impairs function. However, the intrinsic ecological processes and multidimensional driving mechanisms of KRD involving the coupled responses of soil stoichiometry, prokaryotic microbial community function, and plant adaptive strategies remain poorly understood, and the hierarchical driving network governing soil-plant-prokaryote system degradation is unclear. This study aims to elucidate these processes and mechanisms from an integrated perspective of soil stoichiometry, microbial community function, and plant adaptation. Sampling plots were systematically established along a KRD severity gradient. We measured soil physicochemical properties, microbial community structure and putative function, as well as functional traits of dominant plant species. Multivariate statistical methods were employed to disentangle the multi-factor interactive network underlying ecosystem degradation. Main results: 1) KRD significantly declines in soil organic carbon, total nitrogen, and total phosphorus contents (P < 0.05), causing stoichiometric imbalances that soil C:P and N:P increased in moderate KRD (P < 0.05), and C:N decreased in severe KRD (P < 0.05), altering biogeochemical cycling. 2) KRD significantly (P < 0.05) reshaped the prokaryotic microbial community structure, with reduced α-diversity, decreased Acidobacteriota, and enriched Actinobacteriota (P < 0.05); key microbial functions (aerobic chemoheterotrophy, ureolysis) fluctuated significantly (P < 0.05), with ureolysis enhanced in severe KRD. 3) Plants adopted a conservative resource-use strategy, with reduced specific leaf area and increased leaf dry matter content (P < 0.05), most notably in moderate KRD, forming negative plant-soil feedback that reinforces soil impoverishment. 4) SEM uncovered a hierarchical driving network: bedrock exposure rate and vegetation coverage acted as top-level drivers, regulating plant traits and microbial functions, which in turn affected soil enzyme activities and ultimately determined soil nutrient status. KRD is revealed to be a vicious cycle driven by the synergistic interplay of stoichiometric imbalance, microbial functional recession, and plant strategic shift, and effective ecological restoration can be achieved by introducing plant species that mediate positive plant-soil feedbacks to rehabilitate biogeochemical cycling processes.
Chen et al. (Sun,) studied this question.