[Abundance of denitrifying genes and their driving factors in soil under different land use types in the karst region of Northwest Guangxi].

To understand the role of denitrifying microbes during vegetation recovery in karst regions, we determined the basic physicochemical properties and abundance of denitrifying microbial functional genes ( nirS , nirK , fungal nirK , p 450 nor , and nosZ ) of 13 collected soil samples under three land use types (cropland, grassland, and plantation) in Northwest Guangxi, and investigated the changes in the abundance of denitrifying microbial functional genes and their driving factors. Results showed that soil pH, soil organic carbon, total nitrogen (TN), and exchangeable calcium (Ca _exe ) in plantation soil were significantly higher than those in cropland and grassland. The abundance of nirS , nirK , p 450 nor , and nosZ in plantation soil were significantly higher than those in cropland and grassland. Soil pH, TN, and Ca _exe were positively correlated with the abundance of denitrifying functional genes nirS , nirK , and p 450 nor . Results of redundancy analysis showed that soil Ca _exe , pH and TN were the primary factors influencing the abundance of denitrifying functional genes, which accounted for 34.1%, 20.1%, and 16.1% of the total variation, respectively. Such a result suggested that Ca _exe was the main driver of changes in denitrifying functional genes under different land use types. Overall, vegetation restoration (plantation) could effectively increase soil denitrifying microbe genes abundance in the karst region of Northwest Guangxi, and consequently influence soil nitrogen cycling.