Journal Article
Modeled production, oxidation, and transport processes of wetland methane emissions in temperate, boreal, and Arctic regions
Masahito Ueyama; Sara H. Knox; Kyle B. Delwiche; Sheel Bansal; William J. Riley; Dennis Baldocchi; Takashi Hirano; Gavin McNicol; Karina Schafer; Lisamarie Windham‐Myers; Benjamin Poulter; Robert B. Jackson; Kuang‐Yu Chang; Jiquen Chen; Housen Chu; Ankur R. Desai; Sébastien Gogo; Hiroki Iwata; Minseok Kang; Ivan Mammarella; Matthias Peichl; Oliver Sonnentag; Eeva‐Stiina Tuittila; Youngryel Ryu; Eugénie S. Euskirchen; Mathias Göckede; Adrien Jacotot; Mats B. Nilsson; Torsten Sachs
Global Change Biology · Vol. 29, Issue 8 · pp. 2313-2334 · 2023
Abstract
Wetlands are the largest natural source of methane (CH 4 ) to the atmosphere. The eddy covariance method provides robust measurements of net ecosystem exchange of CH 4 , but interpreting its spatiotemporal variations is challenging due to the co‐occurrence of CH 4 production, oxidation, and transport dynamics. Here, we estimate these three processes using a data‐model fusion approach across 25 wetlands in temperate, boreal, and Arctic regions. Our data‐constrained model—iPEACE—reasonably reproduced CH 4 emissions at 19 of the 25 sites with normalized root mean square error of 0.59, correlation coefficient of 0.82, and normalized standard deviation of 0.87. Among the three processes, CH 4 production appeared to be the most important process, followed by oxidation in explaining inter‐site variations in CH 4 emissions. Based on a sensitivity analysis, CH 4 emissions were generally more sensitive to decreased water table than to increased gross primary productivity or soil temperature. For periods with leaf area index (LAI) of ≥20% of its annual peak, plant‐mediated transport appeared to be the major pathway for CH 4 transport. Contributions from ebullition and diffusion were relatively high during low LAI ( 4 production and CH 4 emissions tended to be short in fen sites (3 ± 2 days) and long in bog sites (13 ± 10 days). Based on a principal component analysis, we found that parameters for CH 4 production, plant‐mediated transport, and diffusion through water explained 77% of the variance in the parameters across the 19 sites, highlighting the importance of these parameters for predicting wetland CH 4 emissions across biomes. These processes and associated parameters for CH 4 emissions among and within the wetlands provide useful insights for interpreting observed net CH 4 fluxes, estimating sensitivities to biophysical variables, and modeling global CH 4 fluxes.