SIGNIFICANCE OF STOMATAL CONTROL ON METHANE RELEASE FROM CAREX-DOMINATED WETLANDS

Experiments were conducted in Carex-dominated communities of Arctic and subarctic Alaska to determine the importance of plant stomatal behavior in modifying methane release from wetland plants. Daily methane flux was positively correlated (r = 0.95) with daily leaf conductance at three lake margin sites over an 8-day period. Furthermore, methane flux was reduced significantly following stomatal closure induced by application of an antitranspirant to the plant surface and by enclosure in an opaque chamber. These are the first data to show evidence of stomatal control of release of methane from plants. Significant methane flux continued, however, even with stomatal closure, suggesting that cuticular conductance remains an important mechanism of methane release. The importance of stomatal pathway, relative to the cuticular pathway, is expected to vary through the growing season. These results have significant implications both in the design of chamber-based measurement studies and in interpreting regional to global methane emissions from wetlands.