Dynamics of methane and other greenhouse gases flux in forest ecosystems in China

Swamp Wetlands in Degraded Permafrost Areas Release Large Amounts of Methane and May Promote Wildfires through Friction Electrification

Affected by global warming, permafrost degradation releases a large amount of methane gas, and this part of flammable methane may increase the frequency of wildfires. To study the influence mechanism of methane emission on wildfires in degraded permafrost regions, we selected the northwest section of Xiaoxing’an Mountains in China as the study area, and combined with remote sensing data, we conducted long-term monitoring of atmospheric electric field, temperature, methane concentration, and other observation parameters, and further carried out indoor gas–solid friction tests. The study shows that methane gas (the concentration of methane at the centralized leakage point is higher than 10,000 ppm) in the permafrost degradation area will release rapidly in spring, and friction with soil, surface plant residues, and water vapor will accelerate atmospheric convection and generate electrostatic and atmospheric electrodischarge phenomena on the surface. The electrostatic and atmospheric electrodischarge accumulated on the surface will further ignite the combustibles near the surface, such as methane gas and plant residues. Therefore, the gradual release of methane gas into the air promotes the feedback mechanism of lightning–wildfire–vegetation, and increases the risk of wildfire in degraded permafrost areas through frictional electrification (i.e., electrostatic and atmospheric electrodischarge).

Future Projection of CO2 Absorption and N2O Emissions of the South Korean Forests under Climate Change Scenarios: Toward Net-Zero CO2 Emissions by 2050 and Beyond

Forests mitigate climate change by absorbing CO2. However, N2O emissions in forests, which has 298 times larger global warming potential than CO2, can diminish the climate mitigation role of forests. Thus, it is crucial to project not only CO2 absorption but also N2O emissions in forests to provide a scientific basis for the 1.5 °C Paris Agreement goal. This study used a biogeochemical model, called FBD-CAN, to project CO2 absorption and N2O emissions of South Korean forests from 2021 to 2080 under three climate scenarios, including the current climate, Representative Concentration Pathway (RCP) 4.5, and RCP 8.5. From 2021 to 2080, CO2 absorption decreased from 5.0 to 1.4 Mg CO2 ha—1 year—1 under the current climate with the aging of forests, while N2O emissions increased from 0.25 to 0.33 Mg CO2 eq. ha—1 year—1. Climate change accelerated the decreasing trend in CO2 absorption and the increasing trend in N2O emissions. The subalpine region had a faster decreasing trend in CO2 absorption than the central and southern regions due to its older stand age. These findings provide scientific references for future greenhouse gas reduction plans and broaden our knowledge of the impacts of climate change on the climate mitigation role of forests.