福建省杉木人工林土壤亚硝酸盐还原基因丰度及其主要环境驱动因子

Cunninghamia lanceolata(Chinese fir)is widely planted in subtropical regions of south China,resulting in substantial alteration of soil properties. In order to reveal the distribution patterns of two nitrite reducing genes(nirS and nirK)and their primary driving factors in soils of Chinese fir plantation in Fujian Province,soil samples from nine major forest farms of Chinese fir plantation in Fujian Province were collected to determine the abundance of nirS and nirK genes using real-time quantitative PCR and the potential denitrification rate. Results showed that soil properties varied substantially in Chinese fir plantations in Fujian Province. The pH values range from 4.02 to 5.05,being typical acidic forest soils. The abundance of nirS gene was significantly higher than that of nirK in the soils of all sampling points,indicating that nirS dominated in the acidic Chinese fir plantation soils. Random forest and stepwise regression analysis showed that soil moisture content was a primary factor regulating the abundance of nirS gene, whereas the abundance of nirK gene was mainly regulated by soil pH. Correlation analysis showed that nirS and nirK gene abundances were positively correlated with soil moisture content and pH,respectively. Moreover,soil potential denitrification rate was positively associated with soil environmental factors,such as SOC、DOC、TN、NO₃^- and MC. It also positively associated with the abundance of nirK,rather than nirS. Taken together,the abundance of nirS and nirK gene varies substantially in the soils from Chinese fir plantation in Fujian Province,with moisture content and pH as the key environmental driving factor,respectively.