Investigators:
Gabriel Katul
David S. Ellsworth
Ram Oren
Grants:
"Measurements and Modeling of Net Carbon Exchange over Southeastern Loblolly Pine Plantation at the Duke Forest AmeriFlux Site", NIGEC, $492,000, 2002 - 2004"Measurements and Modeling of Net Carbon Exchange over Southeastern Loblolly Pine Plantation at the Duke Forest AmeriFlux Site", NIGEC, $395,000, 1998 - 2002
"Support to Facilitate Canopy Research at the Duke Forest C-H2O Research Sites", Provost Fund, Duke University, $50,000, 2001 - 2002
"Modeling CO2 fluxes over forest ecosystems", Australian Research Council, Aus$243,286, 2000 - 2002
"Measurements and Modeling of Net Carbon Exchange over Southeastern Loblolly Pine Plantation at the Duke Forest AmeriFlux Site", NIGEC, $290,000, 1995 - 1998
"Spatial variability in turbulent fluxes in the roughness sublayer of an even-aged pine forest.", SRC-NIGEC-DOE, $25,000, 1996 - 1996
Description:
The AmeriFlux network goal is to generate data sets that include net CO2 exchange, and associated physical and physiological parameters that are used to explain spatial and temporal variation in net carbon exchange over dominant ecosystems.The forest dominated by loblolly pine (Pinus taeda L.) is among the most extensive in the Southeast, and loblolly pine is the most planted species in the United States. We monitor net CO2 exchange at the Duke Forest AmeriFlux site year-round over a 16.5 m tall, even-aged loblolly pine plantation. These measurements are accompanied by measurements of ecological variables (including leaf area index, vertical distribution of leaf area density, sap flux, canopy conductance, canopy skin temperature), atmospheric variables (including eddy-covariance water vapor, sensible heat, and momentum fluxes, velocity statistics, air temperature, water vapor concentration and vapor pressure deficit, CO2 concentration profiles inside and above the canopy, photosynthetically active radiation (PAR), net radiation), and soil variables (including soil physical characteristics, soil moisture, soil temperature, soil water potential, and CO2 flux). The measurements (Beginning August - 1997) are available at the Duke Forest AmeriFlux site.
Additional ongoing studies at this site provide a full complement of all core and suggested measurements in the AmeriFlux Science Plan. These measurements are used to describe the relationship between ecosystem net CO2 exchange and environmental variables measured above the canopy (e.g., PAR, VPD). We developed a turbulent transport model that can partition eddy covariance measured fluxes above the canopy into vertical sources and sinks within the canopy for the Duke Forest AmeriFlux pine site. This permits detailed understanding of the effect of physical, physiological, and structural canopy variables on carbon exchange at different layers within the forest canopy. With this model, the impact of annual variability in climate and large seasonal variation in leaf area density (and, in turn, light penetration, atmospheric stability, and leaf physiology) on net ecosystem carbon exchange can be explicitly quantified. With support from the Terrestrial Carbon Processes (TCP) Program of DOE, we monitor the same variables and quantify mass and energy exchanges between the biosphere and atmosphere of two additional ecosystems adjacent to the pine plantation: (1) an abandoned old field, and (2) an 80-year-old oak-hickory forest. This, in combination with the NIGEC supported measurements at the pine forest, comprises a unique AmeriFlux site in which the three major stages of succession, as well as the three most dominating vegetation types in one region, are evaluated for responses to the same atmospheric, hydrologic and edaphic forcing.