Methane (CH4) exchange between trees and the atmosphere has recently emerged as an important, but poorly quantified process regulating global climate. The sources (soil and/or tree) and mechanisms driving the increase of CH4 in trees and degassing to the atmosphere are inadequately understood, particularly for coastal forests facing increased exposure to seawater.
Perhaps among the largest uncertainties in the global CH4 budget is the role of forest trees. While upland forest soils are typically a sink of atmospheric CH4, the emission of CH4 from tree stems to the atmosphere may balance, or even exceed this sink. Our team conducts research in coastal forests around the Pacific Northwest, Mid-Atlantic, and Great Lakes coastlines to understand the mechanisms driving methane emissions from trees. We both measure methane fluxes and concentrations within the stem directly and deploy a variety of novel molecular methods to understand why and how methane is emitted from trees. These methods include genomics techniques to search for evidence of methanogenic and methanotrophic microbes within wood as well as organic chemistry and phsical measurements of wood decay and plant traits. Our team has both led and participated in collaborative research campaigns to gather tree core samples from researchers around the world studying tree methane fluxes to develop understanding across numerous types of environments and climatic conditions. Initial funding for this research was provided by the Pacific Northwest National Laboratory, Lab Directed Research and Development program.