[Response of Soil Nitrifier and Denitrifier Community and Activity to Elevated Atmospheric CO Concentration and Temperature].

Elevated atmospheric CO concentration and temperature may affect nitrifiers and denitrifiers which are related to soil N turnover. A climate change experiment was conducted in the rice-wheat rotation ecosystem. This study was used to investigate effects of elevated CO and temperature on soil microbial community structure, as well as abundance and activity of nitrifiers and denitrifiers. The results showed that no change in the abundance of ammonia-oxidizing bacteria (AOB) and denitrifier was observed at the tillering stage, however at the later stages, elevated CO alone significantly increased the abundance of ammonia-oxidizing archaea (AOA) and denitrifier but there were no changes under CW treatment. The analysis of T-RFLP profiles showed that elevated CO and temperature had no obvious effect on community structure of AOA, AOB or denitrifier, but altered diversity index (') of AOA and denitrifier. Moreover, elevated CO alone significantly increased nitrifying rate at the ripening stage. Elevated CO and temperature did not result in significant change in denitrifying rate at each single stage. These results suggested that effects of elevated CO and temperature on microbial community were different among the tillering, heading and ripening stages, and functional microorganism responded differently to multiple climate change treatments.