Changes in SOC, pH, and Ca associated with microorganism mediated SOC mineralization and temperature sensitivity following vegetation restoration in karst regions

Abstract

Background and aims

Soil organic carbon (SOC) mineralization as a major C loss process, determines soil C accumulation following vegetation restoration in degraded land. However, SOC mineralization and underlying microbial mechanisms are still unclear during vegetation restoration in karst desertification areas, where the soil is characterized by high pH and calcium (Ca) content. This lack of clarity hinders the selection of optimal restoration strategies for adapting to karst conditions.

Methods

Four vegetation restoration strategies, which have undergone 12 years of recovery, were selected: natural shrubland (NS), Cornus Wilsoniana Wanaer (CWW), Eriobotrya japonica (EJ), and Cyclobalanopsis glauca (CG). SOC mineralization and its temperature sensitivity (Q₁₀), soil properties, and microbial communities were measured.

Results

SOC mineralization was highest in NS, which decreased by 24.75%, 18.76%, and 33.66%, respectively, in CWW, EJ, and CG. SOC content and pH associated with fungal community structure positively influenced SOC mineralization, with SOC content having the most direct effect. Q₁₀ was highest in CG compared to the other three strategies. Ca and pH associated with Actinobacteria negatively impacted Q₁₀, while the fungal community structure (particularly Basidiomycota) and bacterial Chao1 had positive effects. Furthermore Ca was the most direct influencing factor.

Conclusions

Vegetation restoration types exhibited different effects on SOC mineralization and Q₁₀ in karst areas. Changes in soil SOC content, pH, and Ca associated with microorganisms mediated SOC mineralization and Q₁₀, with fungi and dominant microbial phyla playing significant roles. This highlights the importance of maintaining soil Ca and pH during vegetation restoration in karst regions.