Forest ecosystem changes from annual methane source to sink depending on late summer water balance

Abstract

Forests dominate the global carbon cycle, but their role in methane (CH₄) biogeochemistry remains uncertain. We analyzed whole-ecosystem CH₄ fluxes from 2 years, obtained over a lowland evergreen forest in Maine, USA. Gross primary productivity provided the strongest correlation with the CH₄ flux in both years, with an additional significant effect of soil moisture in the second, drier year. This forest was a neutral to net source of CH₄ in 2011 and a small net sink in 2012. Interannual variability in the summer hydrologic cycle apparently shifts the ecosystem from being a net source to a sink for CH₄. The small magnitude of the CH₄ fluxes and observed control or CH₄ fluxes by forest productivity and summer precipitation provide novel insight into the CH₄ cycle in this globally important forest ecosystem.

Citation

Shoemaker, Julie K.; Keenan, Trevor F.; Hollinger, David Y.; Richardson, Andrew D. 2014. Forest ecosystem changes from annual methane source to sink depending on late summer water balance. Geophysical Research Letters. 41(2): 673-679.