Eddy Covariance Measurements of Methane Flux at a Tropical Peat Forest in Sarawak, Malaysian Borneo. Issue 9 (5th May 2018)

• Record Type: Journal Article
• Authors: Tang, Angela C. I.; Stoy, Paul C.; Hirata, Ryuichi; Musin, Kevin K.; Aeries, Edward B.; Wenceslaus, Joseph; Melling, Lulie
• Is Part Of: Geophysical research letters. Volume 45:Issue 9(2018)
• Page Start: 4390
• Page End: 4399
• Publication Date: 2018-05-05
• Subjects: methane flux -- tropical peat forest -- eddy covariance; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2017GL076457
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Tropical biogenic sources are a likely cause of the recent increase in global atmospheric methane concentration. To improve our understanding of tropical methane sources, we used the eddy covariance technique to measure CH4 flux (FCH4 ) between a tropical peat forest ecosystem and the atmosphere in Malaysian Borneo over a 2‐month period during the wet season. Mean daily FCH4 during the measurement period, on the order of 0.024 g C‐CH4 ·m −2 ·day −1, was similar to eddy covariance FCH4 measurements from tropical rice agroecosystems and boreal fen ecosystems. A linear modeling analysis demonstrated that air temperature ( T air ) was critical for modeling FCH4 before the water table breached the surface and that water table alone explained some 20% of observed FCH4 variability once standing water emerged. Future research should measure FCH4 on an annual basis from multiple tropical ecosystems to better constrain tropical biogenic methane sources. Plain Language Summary: Methane (CH4 ) is the third most potent greenhouse gas, and its reduction is seen as an effective method for meeting global temperature targets, but the global growth rate of atmospheric CH4 concentration has risen to 10.3 ± 2.1 ppb/year from 2014 to 2016 after a period of relative stagnation from 2000 to 2006. Recent research has pointed to tropical biogenic sources as a likely cause. However, no studies to our knowledge have measured whole‐ecosystem CH4 flux (FCH4 ) from a tropical peat forested wetland to date despite the importance of tropical wetlands to global CH4 budget. To improve our understanding of tropical methane sources, we measured FCH4 between a tropical peat forest ecosystem in Malaysian Borneo and the atmosphere over a 2‐month period during the dry to wet season transition. Mean daily FCH4 during the measurement period, on the order of 0.024 g C‐CH4 ·m −2 ·day −1, are similar to eddy covariance measurements from tropical rice agroecosystems and boreal fen ecosystems. A linear modeling analysis demonstrated the important role of air temperature ( T air ) during unsaturated conditions and water table during saturated conditions and further emphasizes the critical role of simulating temperature and water table accurately for accurate modeled ecosystem scale FCH4 estimates. Key Points: Mean methane flux (FCH4 ) from a tropical peat forest during the early wet season, 0.024 g C‐CH4 /m ‐2 /d ‐1, was similar to tropical rice and boreal fen ecosystems Models explained only 11% of the variance of FCH4 at daily time scales across the entire measurement period Whole‐year whole‐ecosystem FCH4 measurements across multiple tropical ecosystems will help to constrain their role in the global methane budget