After carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are among the most potent greenhouse gases (GHGs), exacerbating global warming. Their rapidly rising concentrations in the atmosphere require urgent action. Forest ecosystems play an important role in the exchange of GHGs with the atmosphere; however, their global role is still far from being understood. It has been shown that not only soils but also trees can emit and/or consume CH4 and N2O in forests. Trees contribute to ecosystem exchanges in various ways. They can uptake and transport soil-produced CH4 and N2O to the atmosphere; produce and consume both gases in situ in tree tissues; and modify carbon and nitrogen turnover in adjacent soils. However, the individual processes involved beyond net ecosystem GHG exchange remain unclear and seem to depend on various factors, including tree characteristics, tree species traits, forest ecosystem type, environmental variables, and seasons. Moreover, there are also other, but still rarely studied co-players in the forest GHG exchange, such as ground vegetation, cryptogamic covers, or water bodies in case of forested wetlands. Interactions between soil, plants, and the atmosphere play a crucial role in controlling the global budget of these gases.

Our session will link scientists studying the CH4 and N2O cycles in forest ecosystems under different climatic, hydrological and scale conditions. This is crucial for improving our understanding of CH4 and N2O exchange in these ecosystems. We welcome contributions on production and consumption processes and mechanisms in soils and plant/tree tissues, as well as gas transport processes within the soil-tree-atmosphere continuum. We highly encourage gas flux measurements from forest soils, cryptogams, ground vegetation, water bodies (in forested wetlands), tree stems, leaves, and canopies using chamber systems or integrated ecosystem approaches (e.g., flux towers with eddy covariance, satellites, or modelling). We also encourage methodological studies investigating CH₄ and N₂O exchange in forest ecosystems.

Solicited author:
Dr. Josep Barba (CREAF, Spain)