[Effects of intensive management on abundance and composition of soil N2-fixing bacteria in Phyllostachys heterocycla stands].

Denaturing gradient-gel electrophoresis and real-time quantitative PCR (qPCR) were employed to determine the effects of intensive management on soil N2-fixing bacteria in a moso bamboo (Phyllostachys heterocycla) plantation. Soil samples were collected from the moso bamboo stands receiving 0 (CK), 10, 15, 20, and 25 years of intensive management. It was found that intensive management caused a strong decrease in soil pH but a general increase in soil available nutrients. The structure of the N2-fixing bacterial communities in the soils having received 10 and 25 years of intensive management were quite similar to that from the CK; however, those from 15 and 20 years of intensification differed from the CK. With increasing time of intensive management, the abundance and diversity of the nifH gene at first decreased and then increased, with the minimum values being observed after 15 years of intensive management, indicating the eventual resiliency of N2-fixing bacteria to disturbance induced by intensive management. Redundancy analysis indicated that soil available potassium, available nitrogen, nitrite nitrogen, and ammonium nitrogen were more closely related to the changes of N2-fixing bacterial community structure compared with the other soil indices measured. In conclusion, the soil N2-fixing bacterial community was negatively affected by intensive management in the short term, but could recover in the long term.