Temperature and Mechanisms of Methane Transport in Trees
Abstract
The mechanisms of methane (CH4) transport through trees are still not well understood. Previous work has established that transport mechanisms likely differ from rice and emergent aquatic plants. Establishing the role of trees in overall plant CH4 emissions requires a thorough understanding of tree transport. Using stable isotope measurements of CH4 assists in elucidating these transport mechanisms. Although it has been shown that CH4 is transported through the stems of trees, emission from leaves by transpiration has not been ruled out. The effect of temperature on these mechanisms is important to the prediction of changes in CH4 emissions from the biosphere in altered global climates. The effect of temperature on methane (CH4) emitted from black cottonwood (Populus trichocarpa) trees has been measured. Trees were grown hydroponically under greenhouse conditions. After several months of growth, CH4 canopy flux was measured over three weeks. Temperatures were altered from 22oC the first week to 25oC the second week and to 18oC the final week. CH4 flux increased with temperature, where the difference in flux between the coolest and warmest week was statistically significant. A Q10 for CH4 flux from trees was calculated to be 2.7. Stable carbon isotope measurements of emitted CH4 were enriched at the warmest temperature compared to the coolest temperature, although all measurements were depleted with respect to the isotopic composition of root water CH4. This data not only gives insight into the temperature effects on CH4 flux from trees, but the mechanisms of CH4 flux themselves. This research was supported in part by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-08ER64515, and through NASA / Oregon Space Grant Consortium, grants NNG05GJ85H and NNX10AK68H.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B51B0551K
- Keywords:
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- 0426 BIOGEOSCIENCES / Biosphere/atmosphere interactions;
- 1615 GLOBAL CHANGE / Biogeochemical cycles;
- processes;
- and modeling