Standing Dead Trees are a Conduit for the Atmospheric Flux of CH4 and CO2 from Wetlands

In vegetated wetland ecosystems, plants can be a dominant pathway in the atmospheric flux of methane, a potent greenhouse gas. Although the roles of herbaceous vegetation and live woody vegetation in this flux have been established, the role of dead woody vegetation is not yet known. In a restored wetland of North Carolina’s coastal plain, static flux chambers were deployed at two heights on standing dead trees to determine if these structures acted as a conduit for methane emissions. Methane fluxes to the atmosphere were measured in five of the chambers, with a mean flux of 0.4 ± 0.1 mg m−2 h−1. Methane consumption was also measured in three of the chambers, with a mean flux of −0.6 ± 0.3 mg m−2 h−1. Standing dead trees were also a source of the flux of CO2 (114.6 ± 23.8 mg m−2 h−1) to the atmosphere. Results confirm that standing dead trees represent a conduit for the atmospheric flux of carbon gases from wetlands. However, several questions remain regarding the ultimate source of these carbon gases, the controls on the magnitude and direction of this flux, the mechanisms that induce this flux, and the importance of this pathway relative to other sources at the landscape level.