Investigating the Carbon Cycle of Switchgrass Through CO2 Flux Measurements and Modelling.

We started eddy covariance measurements of net carbon ecosystem exchange above a commercial switchgrass field in Southern Ontario in January 2012. The switchgrass stand above which the measurements are conducted is in its seventh year since establishment. The eddy covariance measurements will continue for at least another year. We will present the Net Ecosystem Exchange (NEE), Ecosystem Respiration (Re) and Gross Primary Production (GPP) results for this mature switchgrass stand for the year 2012. The gap filling algorithm for the eddy covariance CO₂ flux data will be discussed since it had to be modified to be used for an agricultural site. NEE results will be compared to a corn crop grown under similar climatic conditions.

Furthermore, the measured NEE results from 2012 are used to implement parameters for a switchgrass crop in the DNDC model for soil Greenhouse Gas emissions. First results of the refinement for switchgrass of this process-based model will be presented. Later we will verify the new parameters for modelling switchgrass carbon fluxes against the measurements for 2013. These results will help to assess the Greenhouse Gas benefits from converting land to switchgrass in the future.