FLUXNET-CH 4 : a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands

• Published in: Earth System Science Data
• Main Authors: K. B. Delwiche, S. H. Knox, A. Malhotra, E. Fluet-Chouinard, G. McNicol, S. Feron, Z. Ouyang, D. Papale, C. Trotta, E. Canfora, Y.-W. Cheah, D. Christianson, Ma. C. R. Alberto, P. Alekseychik, M. Aurela, D. Baldocchi, S. Bansal, D. P. Billesbach, G. Bohrer, R. Bracho, N. Buchmann, D. I. Campbell, G. Celis, J. Chen, W. Chen, H. Chu, H. J. Dalmagro, S. Dengel, A. R. Desai, M. Detto, H. Dolman, E. Eichelmann, E. Euskirchen, D. Famulari, K. Fuchs, M. Goeckede, S. Gogo, M. J. Gondwe, J. P. Goodrich, P. Gottschalk, S. L. Graham, M. Heimann, M. Helbig, C. Helfter, K. S. Hemes, T. Hirano
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental sciences; GE1-350; Geology; QE1-996.5; Arctic
• Online Access: https://doi.org/10.5194/essd-13-3607-2021; https://doaj.org/article/1a0b0d8493814f1ab3b2b9bac057e320

Methane (CH 4 ) emissions from natural landscapes constitute roughly half of global CH 4 contributions to the atmosphere, yet large uncertainties remain in the absolute magnitude and the seasonality of emission quantities and drivers. Eddy covariance (EC) measurements of CH 4 flux are ideal for constraining ecosystem-scale CH 4 emissions due to quasi-continuous and high-temporal-resolution CH 4 flux measurements, coincident carbon dioxide, water, and energy flux measurements, lack of ecosystem disturbance, and increased availability of datasets over the last decade. Here, we (1) describe the newly published dataset, FLUXNET-CH 4 Version 1.0, the first open-source global dataset of CH 4 EC measurements (available at https://fluxnet.org/data/fluxnet-ch4-community-product/ , last access: 7 April 2021). FLUXNET-CH 4 includes half-hourly and daily gap-filled and non-gap-filled aggregated CH 4 fluxes and meteorological data from 79 sites globally: 42 freshwater wetlands, 6 brackish and saline wetlands, 7 formerly drained ecosystems, 7 rice paddy sites, 2 lakes, and 15 uplands. Then, we (2) evaluate FLUXNET-CH 4 representativeness for freshwater wetland coverage globally because the majority of sites in FLUXNET-CH 4 Version 1.0 are freshwater wetlands which are a substantial source of total atmospheric CH 4 emissions; and (3) we provide the first global estimates of the seasonal variability and seasonality predictors of freshwater wetland CH 4 fluxes. Our representativeness analysis suggests that the freshwater wetland sites in the dataset cover global wetland bioclimatic attributes (encompassing energy, moisture, and vegetation-related parameters) in arctic, boreal, and temperate regions but only sparsely cover humid tropical regions. Seasonality metrics of wetland CH 4 emissions vary considerably across latitudinal bands. In freshwater wetlands (except those between 20 ∘ S to 20 ∘ N) the spring onset of elevated CH 4 emissions starts 3 d earlier, and the CH 4 emission season lasts 4 d longer, for each degree Celsius ...