Large quantities of soil organic carbon are accumulated in wetland ecosystems, which may become vulnerable under global warming conditions in permafrost regions. The Xing’an Mountain Range is one of the major wetland and permafrost distribution regions in China. The area is also the southern limit of global permafrost due to a mean annual air temperature above zero. Global warming has caused rapid permafrost thawing in recent years. However, few papers have reported greenhouse gas emissions from wetlands under permafrost thawing conditions in this region. This research aims to reveal the effects of permafrost thawing on peatland CH4 and N2O emissions in this region and their potential feedback to global warming. We observed during four growing seasons (2011-2014) in-situ CH4 and N2O emissions from peatlands under permafrost severe thawing, moderate thawing, and no thawing conditions in the Xing’an Mountains utilizing the static chamber method.
Results/Conclusions
Seasonal variation of peatland CH4 emissions became more aggravation with the intensification of permafrost thawing. CH4 emission peaks became larger and CH4 absorption decreased until no CH4 absorptions were observed with permafrost thawing. Seasonal mean CH4 emissions from peatland permafrost undergoing severe thawing, moderate thawing, and no thawing were 6.58 mgm-2h-1, 0.38 mgm-2h-1 and 0.12 mgm-2h-1, respectively. CH4 emission increases were caused by the expansion of the permafrost active thawing layer and the subsequent changes of increased soil temperature, water table and changed vegetation composition. However, seasonal variations of N2O emission and their accumulated emissions did not change with permafrost thawing. Increased CH4 emissions from thawing peatland may cause further positive feedback to global warming. However, there was no positive feedback of N2O emissions to global warming in our regional research.