Controls on methane flux from terrestrial ecosystems in Agricultural Ecosystem Effects on Trace Gases and Global Climate Change. L. Harper, A. Mosier, J. M. Duxbury, and D. Rolston, (eds.)

This chapter identifies some of the key controls on Methane (CH4) flux between terrestrial ecosystems and the atmosphere, and discusses new research that begins to address them. It focuses on CH4 production, CH4 consumption, their interactions and the role of plant and soil-mediated transport to the atmosphere. CH4 consumption occurs in all aerobic soils and can serve two distinct ecological roles. First, CHconsumption in the aerobic surface soil and rhizosphere of wetlands can provide a barrier to efflux of CH4 produced at depth, and if the water table drops far enough it can become a sink. Second, CH4 consumption in upland soils acts as a net sink for atmospheric CH4. Predicting changes in CH4 over time requires incorporating the major controls on CH4 consumption into large-scale models. Nitrogen availability appears to be an important control on CH4 consumption in upland systems, while O2 may be important in wetlands.