Spatial-temporal Dynamics of Coupled Greenhouse Gas and Energy Fluxes in the California Delta

Temperate peatlands are hotspots of soil carbon storage and biological diversity, and are extremely vulnerable to management decisions that alter water levels. They provide key economic (grazing, peat production) and ecosystem (filters for upslope pollutants and nitrogen, carbon sequestration) services. They are also potentially important sinks of carbon dioxide or sources of carbon dioxide or methane. So interactions between terrestrial biogeochemistry and the hydrological cycle are likely determinants of their role in global warming.

We have a current NSF-funded project that uses experimental and modeling approaches to determine the biophysical processes that control coupled flues of carbon dioxide, water and methane in a temperate peatland in the California Delta: Sherman Island. We will quantify the land-atmosphere exchange of carbon and water, and integrate these fluxes across a spectrum of time and space through field-based measurements, remote sensing and spatial modeling.

Ground based quasi-continuous eddy covariance measurements of methane, carbon dioxide and water vapor fluxes are being made to study paddock-scale fluxes on daily, seasonal and interannual time scales. A new and novel Laser Absorption Spectrometer will be used to measure methane fluxes. The biophysical processes controlling methane, carbon dioxide and water exchange will be studied with periodic chamber-based measurements of carbon efflux. A suite of controlling abiotic (water table, pressure fluctuations, temperature, soil moisture, oxygen) and biotic (leaf area index, plant functional type, isotope discrimination) factors will be quantified to interpret the fluxes. The methane and carbon dioxide flux observations derived from the ground instruments need to be upscaled to the regional space scale and annual time scales using a combination of MODIS imagery and a comprehensive geographical information system (GIS) to drive a methane emission model for the Delta region. The methane emission model will be based on empirical algorithms developed and validated at the field site.

Personnel on the project: Matteo Detto, is a micrometeorologist from the University of Milano is working in the Baldocchi Biometeorology laboratory. He is responsible for the collection, processing and analysis of eddy flux data of carbon dioxide, water vapor and methane exchange. Yit The, is a biogeochemist from UC Berkeley and is working in the Silver Lab and is responsible for collecting chamber-based measurements of methane and CO2 exchange and for conducting process-based studies on the controls of methane and CO2 exchange. Oliver Sonnetag from the University of Toronto and will be responsible for modeling and upscaling carbon, water and energy fluxes regionally.

Collaborators on this project include Dennis Baldocchi (PI) and Whendee Silver (C0-PI).