Wetland flux controls: how does interacting water table levels and temperature influence carbon dioxide and methane fluxes in northern Wisconsin?
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Wetlands play a disproportionately large role in global terrestrial carbon stocks, and from 1 year to the next individual wetlands can fluctuate between carbon sinks and sources depending on factors such as hydrology, temperature, and land use. Although much research has been done on short-term seasonal to annual wetland biogeochemical cycles, there is a lack of experimental evidence concerning how the reversibility of wetland hydrological changes will influence these cycles over longer time periods. Five years of drought-induced declining water table at Lost Creek, a shrub fen wetland in northern Wisconsin, coincided with increased ecosystem respiration (Reco) and gross primary production (GPP) as derived from long-term eddy covariance observations. Since then, however, the average water table level at this site has increased, providing a unique opportunity to explore how wetland carbon fluxes are affected by interannual air temperature differences as well as changing water table levels. Water table level, as measured by water discharge, was correlated with Reco and GPP at interannual time scales. However, air temperature had a strong correlation with Reco, GPP, and net ecosystem productivity (NEP) at monthly time scales and correlated with NEP at inter-annual time scales. Methane flux was strongly temperature-controlled at seasonal time scales, increasing an order of magnitude from April to July. Annual methane emissions were 51 g C m−2. Our results demonstrate that over multi-year timescales, water table fluctuations can have limited effects on wetland net carbon fluxes and instead at Lost Creek annual temperature is the best predictor of interannual variation.
KeywordsEddy covariance Carbon flux Wetlands
The authors would like to thank Jonathan Thom for technical field help at US‐Los and Yost R. for dogged assistance throughout analysis. Flux data is archived as part of the FLUXNET 2015 data release, discharge data is archived by the USGS and MODIS NDVI data is archived by Oak Ridge National Laboratory. This work was supported National Science Foundation Atmospheric and Geospace Sciences Postdoctoral Fellowship Program (#GEO-1430396), the U.S. Department of Energy (DOE) Office of Biological and Environmental Research (BER), National Institute for Climatic Change Research (NICCR) Midwestern Region Subagreement 050516Z19, and Department of Energy Lawrence Berkeley National Laboratory Ameriflux Network Management Project Subcontract to ChEAS Core Site Cluster. B. Sulman is supported by award NA14OAR4320106 from the National Oceanic and Atmospheric Administration, U.S. Department of Commerce. The statements, findings, conclusions, and Recommendations are those of the author(s) and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration, or the U.S. Department of Commerce.
- Anderson FE, Bergamaschi B, Sturtevant C, Knox S, Hastings L, Windham-Myers L, Detto M, Hestir EL, Drexler J, Miller RL, Matthes JH, Verfaillie J, Baldocchi D, Snyder RL, Fujii R (2016) Variation of energy and carbon fluxes from a restored temperate freshwater wetland and implications for carbon market verification protocols. J Geophys Res 121(3):777–795CrossRefGoogle Scholar
- Arneth A, Kurbatova J, Kolle O, Shibistova OB, Lloyd J, Vygodskaya NN, Schulze ED (2002) Comparative ecosystem–atmosphere exchange of energy and mass in a European Russian and a central Siberian bog II. Interseasonal and interannual variability of CO2 fluxes. Tellus B 54(5):514–530Google Scholar
- Baldocchi D, Falge E, Gu L, Olson R, Hollinger D, Running S, Anthoni P, Bernhofer C, Davis K, Evans R (2001) FLUXNET: a new tool to study the temporal and spatial variability of ecosystem–scale carbon dioxide, water vapor, and energy flux densities. Bull Am Meteorol Soc 82(11):2415–2434CrossRefGoogle Scholar
- Megonigal JP, Conner WH, Kroeger S, Sharitz RR (1997) Aboveground production in southeastern floodplain forests: a test of the subsidy–stress hypothesis. Ecology 78(2):370–384Google Scholar
- Menon S, Denman KL, Brasseur G, Chidthaisong A, Ciais P, Cox PM, Dickinson RE, Hauglustaine D, Heinze C, Holland E (2007) Couplings between changes in the climate system and biogeochemistry. In: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CAGoogle Scholar
- Papale D, Reichstein M, Aubinet M, Canfora E, Bernhofer C, Kutsch W, Longdoz B, Rambal S, Valentini R, Vesala T, Yakir D (2006) Towards a standardized processing of net ecosystem exchange measured with eddy covariance technique: algorithms and uncertainty estimation. Biogeosciences 3(4):571–583CrossRefGoogle Scholar
- Reichstein M, Falge E, Baldocchi D, Papale D, Aubinet M, Berbigier P, Bernhofer C, Buchmann N, Gilmanov T, Granier A, Grünwald T, Havránková K, Ilvesniemi H, Janous D, Knohl A, Laurila T, Lohila A, Loustau D, Matteucci G, Meyers T, Miglietta F, Ourcival J-M, Pumpanen J, Rambal S, Rotenberg E, Sanz M, Tenhunen J, Seufert G, Vaccari F, Vesala T, Yakir D, Valentini R (2005) On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm. Glob Change Biol 11(9):1424–1439CrossRefGoogle Scholar
- Seabold S, Perktold J (2010) Statsmodels: econometric and statistical modeling with python. In: Proceedings of the 9th python in science conference, vol 57, p 61Google Scholar
- Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (2013) Climate change 2013: The physical science basis. Intergovernmental panel on climate change, working Group I contribution to the IPCC fifth assessment report (AR5). Cambridge University Press, New YorkGoogle Scholar
- Whiting GJ, Chanton JP (2001) Greenhouse carbon balance of wetlands: methane emission versus carbon sequestration. Tellus B 53(5):521–528Google Scholar