Greenhouse gas fluxes from different types of permafrost regions in the Daxing'an Mountains, Northeast China.

Global warming will increase the greenhouse gas (GHG) fluxes of permafrost regions. However, little is known about the difference in GHG fluxes among different types of permafrost regions. In this study, we used the static opaque chamber and gas chromatography techniques to determine the fluxes of carbon dioxide (CO), methane (CH), and nitrous oxide (NO) in predominantly continuous permafrost (PCP), predominantly continuous and island permafrost (PCIP), and sparsely island permafrost (SIP) regions during the growing season. The main factors causing differences in GHG fluxes among three types of permafrost regions were also analyzed. The results showed mean CO fluxes in SIP were significantly higher than that in PCP and PCIP, which were 342.10 ± 11.46, 105.50 ± 10.65, and 127.15 ± 14.27 mg m h, respectively. This difference was determined by soil temperature, soil moisture, total organic carbon (TOC), nitrate nitrogen (NO-N), and ammonium nitrogen (NH-N) content. Mean CH fluxes were -26.47 ± 48.83 (PCP), 118.35 ± 46.93 (PCIP), and 95.52 ± 32.86 μg m h (SIP). Soil temperature, soil moisture, and TOC content were the key factors to determine whether permafrost regions were CH sources or sinks. Similarly, PCP behaved as the sink of NO, PCIP and SIP behaved as the source of NO. Mean NO fluxes were -3.90 ± 1.71, 0.78 ± 1.55, and 3.78 ± 1.59 μg m h, respectively. Soil moisture and TOC content were the main factors influencing the differences in NO fluxes among the three permafrost regions. This study clarified and explained the differences in GHG fluxes among three types of permafrost regions, providing a data basis for such studies.