Soil denitrification plays a crucial role in regulating soil nitrogen availability during vegetation restoration. However, there is limited evidence revealing the mechanisms involving the abundance, diversity, composition, and interactions of denitrifying microorganisms in driving soil denitrification remain unclear, particularly in vegetation restoration scenarios within karst ecosystems. This study investigated the association 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 strategies increased denitrification rates by 45%–170%, with the highest rates observed in the combination of plantation forest and forage grass, accompanied by reduced nitrate levels. The abundance of nirK - and nirS -harboring denitrifiers was higher in plantation forest and the combination of plantation forest and forage grass relative to cropland soils, and plantation forest soils also exhibiting higher nirS richness. Co-occurrence network analysis indicated enhanced microbial interactions in vegetation restoration, particularly for nirK - harboring microorganisms across all strategies and for nirS in the combination of plantation forest and forage grass, evidenced by enhanced topological features such as node and edge counts. Notably, while nirK abundance and nirS richness significantly contributed to denitrification rate variations, their network complexity was identified as the dominant predictor. Thus, vegetation restoration, particularly the combination of plantation forest and forage grass, accelerates soil denitrification rates primarily by fostering interspecies interactions among denitrifying microorganisms, alongside increases in the abundance and richness of denitrifying communities. These findings offer valuable insights for optimizing vegetation restoration strategies to improve soil nitrogen cycling through targeted management of denitrifying microorganisms and their interactions. • Soil denitrification rates increase in vegetation restoration compared to cropland. • Vegetation restoration increases denitrifier abundance and restructures their community composition. • Denitrifier network complexity and abundance were the main drivers of denitrification rates.
Sun et al. (Sun,) studied this question.