Effects of Climate Change on CH4 and N2O Fluxes from Temperate and Boreal Forest Soils

Abstract

Temperate and boreal forest ecosystems cover approximately 13% of the world terrestrial surface and provide a wide range of ecological services to society, including a significant contribution to the regulation of atmospheric greenhouse gas concentrations. Forests do not only function as major sinks (and sources) for atmospheric carbon dioxide (CO2) but also as significant sources and sinks of other atmospheric greenhouse gases, namely, nitrous oxide (N2O) and methane (CH4). The importance of forests as regulators of atmospheric concentrations of these trace gases is undebated, but how this function might change in view of the ongoing climate and associated environmental changes remains a matter of debate. On the one hand, increases in temperature and atmospheric CO2 could lead to permafrost thaw, dramatically increasing N transformation rates in the soil and associated N2O emissions. On the other hand, declining precipitation or changes toward more episodic rainfall events might result in the opposite, through reduced N2O efflux and stimulated uptake of atmospheric CH4 by forest soils. By providing a set of examples from field and laboratory studies, we present the current knowledge and the research perspectives aiming at a better understanding of the current and future role of boreal and temperate forest soils as regulators of the atmospheric concentrations of N2O and CH4 in the frame of global change.