Data for Soil denitrification rates, the abundance, diversity, composition, and interactions of denitrifying microorganisms under vegetation restoration in karst ecosystem.

Soil denitrification is a crucial process regulating soil nitrogen availability during vegetation restoration. However, the mechanisms involving the abundance, diversity, composition, and interactions of denitrifying microorganisms remain unclear, particularly in short-term vegetation restoration scenarios within fragile ecosystems. In this study, we investigated the relationship between soil denitrification rates and microbial traits across three vegetation restoration strategies in karst areas: forage grass, plantation forest, and a combination of plantation forest and forage grass. Compared to cropland, all vegetation restoration strategies increased soil denitrification rates by 45%–170%, with the highest rates observed in the combination of plantation forest and forage grass, alongside reduced nitrate nitrogen content in all restored treatments. Vegetation restoration also significantly altered the abundance, diversity, community composition, and interactions of denitrifying microorganisms. Specifically, the abundance of nirK- and nirS-harboring denitrifiers increased significantly under plantation forest and the combination of plantation forest and forage grass relative to control soils. Additionally, nirS richness was notably higher in plantation forest soils than in control soils. Co-occurrence network analysis indicated greater microbial interaction complexity under vegetation restoration than in the control, evidenced by enhanced topological features such as node and edge counts, particularly for nirK-carrying microorganisms across all strategies and for nirS in the combination of plantation forest and forage grass. Notably, while nirK abundance and nirS richness significantly contributed to soil denitrification rate changes, nirK and nirS network complexity were identified as the primary determinant of these rates. Thus, vegetation restoration, particularly the combination of plantation forest and forage grass, enhances soil denitrification rates by fostering interspecies interactions among denitrifying microorganisms, reducing nitrate nitrogen availability. These findings offer valuable insights for optimizing vegetation restoration strategies to improving soil nitrogen cycling through targeted management of denitrifying microorganisms and their interactions.