Controls of Net Ecosystem Exchange at an Old Field, a Pine Plantation, and a Hardwood Forest under Identical Climatic and Edaphic Conditions


A Joint Project with Florida State University at Tallahassee (FSU Contact: Jeffrey Chanton )

Sponsored by: Terrestrial Carbon Program - Environmental Sciences Division, Office of Biological & Environmental Research, Department of Energy


We augmented the Duke AmeriFlux site with a capability to quantify CO2 fluxes over three vegetation/land cover types, all of which are equipped with towers and related infrastructure, and in close proximity to each other: (1) an AmeriFlux tower site (supported by DOE-NIGEC-SERC) in a loblolly pine plantation planted in 1983, (2) an AmeriFlux tower site in a mature hardwood forest (equipped by DOE-NIGEC-SERC and NSF) and now supported by DOE's Terrestrial Carbon Program (TCP), and (3) an abandoned old field tower site (equipped with NSF support, operated occasionally with support by EPA) and now supported by DOE's TCP.

Quantifying net ecosystem carbon exchange (NEE) over these very different and prevalent cover types, representing distinct states in a common southeast succession, yet all subjected to the same climatic forcing and edaphic conditions, will permit us to deconvolve the effect of vegetation type from that of climate and soil on NEE, and will provide requisite information for up-scaling to regional NEE from the vegetation mosaic. In addition, we perform continuous measurements of soil CO2 efflux, and partition the flux in the three vegetation types to its autotrophic and heterotrophic components, at different seasons and under different water availability conditions, using CO2 isotope measurements of both 13C and 18O.

These and additional eco-physiological measurements will be used to parameterize a modified CANVEG model, and a Lagrangian transport model that deconvolve the sources of respiration, both of which have been tested and performed well in the pine plantation. In addition to delivering continuous flux and ancillary measurements from three vegetation types to CDIAC, we quantify the response of the three vegetation types to temporal variation in climate and soil moisture conditions.

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