杉木人工林根际土壤氧化亚氮还原基因特征及其 影响因素

[Objective] Nitrous oxide (N₂O)-reducing microbes are the only known microbial group capable of eliminating N₂O. The abundance, diversity, community structure, and influencing factors of their functional gene (nosZ) are critical for N₂O removal. Cunninghamia lanceolata is a widely planted timber species in southern China, and its rhizosphere represents a hotspot for both N₂O production and reduction. However, the spatial distribution pattern of nosZ Ⅰ genes and their driving factors in the rhizosphere soils of C. lanceolata plantations remain unclear. [Methods] We investigated the rhizosphere soils of C. lanceolata plantations from five state-owned forest farms— Qiujiashan, Wuyi, Guanzhuang, Xiayang, and Xiapu—in Fujian Province. Quantitative PCR and amplicon sequencing were employed to analyze the abundance, diversity, and community structure of nosZ Ⅰ genes and to identify their key environmental drivers.[Results] Dissolved organic carbon concentrations in rhizosphere soils ranged from 6.91 mg/kg to 23.52 mg/kg, being significantly lower in Guanzhuang and Xiayang than in Wuyi, Qiujiashan, and Xiapu. The nosZ I gene abundance ranged from 4.76×10⁶ copies/g to 36.50×10⁶ copies/g, reaching 36.50×10⁶ copies/g and 29.08×10⁶ copies/g in Guanzhuang and Xiayang, respectively, which significantly exceeded those in Qiujiashan, Wuyi, and Xiapu. Dissolved organic carbon emerged as the primary driver of nosZ I gene abundance, which implied that low dissolved organic carbon may promote the proliferation of N₂O-reducing bacteria. The Shannon index of nosZ I genes ranged from 4.41 to 5.67, being significantly higher in Xiayang than in Wuyi and Xiapu and the lowest in Xiapu. Total carbon was the key factor affecting the Shannon index. The nosZ I community structures in Qiujiashan, Guanzhuang, and Xiapu were similar, whereas that of Xiayang was significantly different from the others. Soil pH was identified as the main driver of community structure, and Xiayang had a significantly higher pH than the other sites. The dominant bacterial class in the rhizosphere soils of all five forest farms was Gammaproteobacteria. Xiayang had significantly lower relative abundance of Gammaproteobacteria but significantly higher relative abundance of Alphaproteobacteria than other farms. [Conclusion] Soil carbon content and pH are key environmental factors regulating the abundance, diversity, and community structure of N₂O-reducing bacteria in the rhizosphere soils of C. lanceolata plantations, potentially influencing N₂O removal and mitigation potential. Therefore, the management strategies for C. lanceolata plantations should consider regulating soil carbon content and pH to optimize N₂O mitigation effects and alleviate global climate change.