AUTHOR=Song Yanyu , Cheng Xiaofeng , Song Changchun , Li Mengting , Gao Siqi , Liu Zhendi , Gao Jinli , Wang Xianwei 

TITLE=Soil CO2 and N2O emissions and microbial abundances altered by temperature rise and nitrogen addition in active-layer soils of permafrost peatland

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1093487

DOI=10.3389/fmicb.2022.1093487

ISSN=1664-302X

ABSTRACT=<p>Changes in soil CO<sub>2</sub> and N<sub>2</sub>O emissions due to climate change and nitrogen input will result in increased levels of atmospheric CO<sub>2</sub> and N<sub>2</sub>O, thereby feeding back into Earth’s climate. Understanding the responses of soil carbon and nitrogen emissions mediated by microbe from permafrost peatland to temperature rising is important for modeling the regional carbon and nitrogen balance. This study conducted a laboratory incubation experiment at 15 and 20°C to observe the impact of increasing temperature on soil CO<sub>2</sub> and N<sub>2</sub>O emissions and soil microbial abundances in permafrost peatland. An NH<sub>4</sub>NO<sub>3</sub> solution was added to soil at a concentration of 50 mg N kg<sup>−1</sup> to investigate the effect of nitrogen addition. The results indicated that elevated temperature, available nitrogen, and their combined effects significantly increased CO<sub>2</sub> and N<sub>2</sub>O emissions in permafrost peatland. However, the temperature sensitivities of soil CO<sub>2</sub> and N<sub>2</sub>O emissions were not affected by nitrogen addition. Warming significantly increased the abundances of methanogens, methanotrophs, and <italic>nir</italic>K-type denitrifiers, and the contents of soil dissolved organic carbon (DOC) and ammonia nitrogen, whereas <italic>nir</italic>S-type denitrifiers, β-1,4-glucosidase (βG), cellobiohydrolase (CBH), and acid phosphatase (AP) activities significantly decreased. Nitrogen addition significantly increased soil <italic>nir</italic>S-type denitrifiers abundances, β-1,4-N- acetylglucosaminidase (NAG) activities, and ammonia nitrogen and nitrate nitrogen contents, but significantly reduced bacterial, methanogen abundances, CBH, and AP activities. A rising temperature and nitrogen addition had synergistic effects on soil fungal and methanotroph abundances, NAG activities, and DOC and DON contents. Soil CO<sub>2</sub> emissions showed a significantly positive correlation with soil fungal abundances, NAG activities, and ammonia nitrogen and nitrate nitrogen contents. Soil N<sub>2</sub>O emissions showed positive correlations with soil fungal, methanotroph, and <italic>nir</italic>K-type denitrifiers abundances, and DOC, ammonia nitrogen, and nitrate contents. These results demonstrate the importance of soil microbes, labile carbon, and nitrogen for regulating soil carbon and nitrogen emissions. The results of this study can assist simulating the effects of global climate change on carbon and nitrogen cycling in permafrost peatlands.</p>