Greenhouse gas emissions from permafrost peatland of the Daxing'an Mountains under the effects of dry-rewetting conditions.

The soil carbon cycle in permafrost peatlands is influenced by the dry-rewetting (DRW) cycle. The variations in the greenhouse gas (GHG) contributions under different temperature conditions caused by DRW are not yet systematically understood. This study aimed to investigate the interactive effects of DRW cycles and warming on GHG emissions from permafrost peatlands in the Daxing'an Mountains and quantify their contribution to global warming potential (GWP). Soils from the center and edge of a peatland were subjected to two temperatures (15 and 25 °C) and five moisture treatments under indoor experimental conditions. The dynamics of CO2, CH4, and N2O fluxes were systematically monitored. The results revealed that warming significantly amplified GHGs. At 25 °C, intense DRW drove mean daily CO2 emissions to 64.2-116.7 mg kg-1 d-1, which was 1.33-2.01 times the rate of the submerged controls. In contrast, these same DRW treatments suppressed CH4 emissions dramatically, which reduced them from 3.35 to 9.31 mg kg-1 d-1 under submerged conditions to as low as 0.08-1.94 mg kg-1 d-1. Under submerged conditions at 25 °C, the GWP was dominated by CH4 (contributing 65-84 %), which shifted to CO2 dominance (contributing 64 %-85 %) under drainage conditions. The GHG response exhibited significant spatial heterogeneity. The center of the peatland showed strong interactive effects between temperature and hydrology. The initial permafrost degradation stage was accompanied by inundation (GWP 4.1-6.6 times the current level). GHG emissions from permafrost peatlands were significantly affected by the interplay of temperature and hydrology. Accurately predicting peatland feedback to climate change requires an integrated approach that considers coupled hydro-thermal effects, spatial heterogeneity, and the dynamic trade-off between CO2 and CH4.