Methane (CH4) and nitrous oxide (N2O) are among the most important greenhouse gases (GHG) after carbon dioxide (CO2) in accelerating global warming and deserve special attention as their concentrations increase. Forest ecosystems play an important role in the exchange of GHGs with the atmosphere. It has been shown that not only soils but also trees play a significant role in the net exchange of CH4 and N2O in forests. Trees can contribute to ecosystem exchange by uptake and transport of soil-produced CH4 and N2O to the atmosphere, by in situ production and consumption of both gases in plant tissues, and by modifying carbon and nitrogen turnover in adjacent soils. However, the contribution of these individual processes to the net ecosystem GHG exchange is still unclear and appears to depend on many aspects such as tree species (tree traits), forest ecosystem type, environmental parameters and seasonal dynamics. Soil-tree-atmosphere interactions play a crucial role in controlling the global budget of these gases.

This session aims to bring together scientists working on CH4 and N2O cycles in forest ecosystems across different climatic and hydrological ranges and scales, which is crucial for improving our understanding of CH4 and N2O exchange in forest ecosystems. We welcome contributions on production and consumption processes and mechanisms in soils and plant tissues, as well as on gas transport processes in the soil-tree-atmosphere continuum. Gas flux measurements from forest soils, cryptogams, tree stems, leaves or canopies with chamber systems or integrated ecosystem approaches (flux tower with eddy covariance, satellite or modelling) would be highly appreciated. Methodological studies closely related to the investigation of CH4 and N2O exchange in forest ecosystems are also welcome.

Solicited author:
Prof. Daniel Epron (University of Kyoto, Japan)