Abstract:
Methane (CH4) emissions from wetlands significantly contribute to the global atmospheric CH4 budget. Tree stems are increasingly recognized as important conduits for CH4 transport from wetlands to the atmosphere, yet our understanding of the factors controlling stem CH4 emissions remains limited. In this study, we continuously monitored tree stem CH4 emissions from three common wetland tree species (Salix nigra, Acer rubrum, and Nyssa aquatica) over two growing seasons in a temperate freshwater forested wetland. We examined the temporal dynamics of stem CH4 emissions and investigated the influence of environmental factors, including season, location within the wetland, and hydrological conditions. Our results showed that tree stem CH4 emissions exhibited distinct seasonal patterns, peaking during the summer months and declining during the fall and winter. Stem CH4 emissions also varied spatially within the wetland, with higher emissions observed in areas with higher soil moisture content and lower redox potential. Hydrological conditions, particularly flooding events, significantly increased stem CH4 emissions, suggesting that flooding promotes the production and transport of CH4 through tree stems. Our findings highlight the importance of considering seasonal, spatial, and hydrological factors when estimating CH4 emissions from forested wetlands and provide valuable insights for improving our understanding of wetland CH4 dynamics.
