Greenhouse gas emissions from different vegetation types in the permafrost region of the Daxing'an Mountains under drying-rewetting conditions.

The alterations in climatic conditions have led to soil drying-rewetting (DRW) events in permafrost regions, which result in heightened emissions of greenhouse gas (GHG). However, there is currently a lack of comprehensive research on GHG emissions from permafrost under the DRW conditions. To reveal the changes of GHG emissions in permafrost, laboratory simulation experiments were conducted on 0-60 cm active layer soil in four soil ecosystems (Larix gmelinii, Betula platyphylla, mix of L. gmelinii and B. platyphylla, peatland) of the Daxing'an Mountains, northeast China. A 210-day soil cultivation experiment was conducted to investigate the effects of DRW on soil physicochemical properties and GHG emissions. The research showed that all soils exhibited emission sources of carbon dioxide (CO2) and nitrous oxide (N2O). The mean fluxes of CO2, N2O, and CH4 in peatlands with DRW were 520.33 ± 374.24 mg m-2 h-1, 167.96 ± 112.24 μg m-2 h-1, and 1.02 ± 2.84 μg m-2 h-1, respectively. Mean CO2 flux from peat soil increased by 2.10 times with DRW, and mean N2O flux increased by 1.74 times for the soil of B. platyphylla. CO2 and N2O emissions exhibited variability during DRW. CH4 emissions were lower under the soil DRW compared to constant moisture treatment. The influence of these alternating conditions on soil GHG fluxes was substantial at 25 °C. The DRW conditions had no significant effect on CH4 in three types of forest soils. This study offers valuable insights for accurately predicting the impact of climate warming on changes in permafrost soil.