Plant and Microbial Carbon Flux Coherence within Managed and Agricultural Wetlands of the California Delta
Previously Published Material: Summary findings for the carbon budgets from the sites were presented at the AGU Fall Meeting by Sara Knox, and pieces of this presentation have been published in the following publications:Matthes, J. H., C. Sturtevant, J. Verfaillie, S. H. Knox, D. D. Baldocchi. 2014. Parsing variability in CH4 fluxes at a spatially heterogeneous wetland: Integrating multiple eddy covariance towers with high-resolution flux footprint analysis. Journal of Geophysical Research – Biogeosciences, 119, doi: 10.1002/2014JG002642. Hatala, J. A., M. Detto, D. D. Baldocchi. 2012b. Gross ecosystem productivity causes a diurnal pattern in methane flux from rice. Geophysical Research Letters 39(6): L06409, doi:10.1029/2012GL051303.
English Abstract:
Global wetlands are biogeochemical hotspots for carbon cycling, with high rates of plant productivity, high rates of soil carbon accumulation, and the production of methane through anaerobic decomposition. The research presented in this talk measured direct wetland-atmosphere exchange of carbon dioxide (CO2) and methane (CH4) fluxes using a network of eddy covariance towers at drained, agricultural, and restored temperate peatlands in the California Delta since 2009. Using these data, we tested hypotheses regarding the temporal and spatial coupling between landscape-scale CO2 and CH4 flux to investigate questions regarding the coherence between plant productivity and microbial methane flux. We investigated the coupling between gross primary productivity (GPP) and CH4 at a spatially homogeneous agricultural rice paddy using wavelet Granger causality analysis, and found that the diel cycling of GPP played a dominant role in modulating a diel pattern in CH4 flux. At a spatially heterogeneous restored wetland, we synthesized remotely sensed imagery with eddy covariance measurements with a flux footprint model and investigatde the relative controls of large-scale environmental drivers and small-scale footprint variability on the measured CH4 flux. Refining our understanding of the spatiotemporal scales through which CH4 flux is modulated by plant productivity provided important insights for future mechanistic modeling efforts and highlighted critical considerations for the potential of using wetland restoration to create atmospheric sinks for greenhouse gases in California.
