HR: 0800h
AN: H51D-1188    [Abstracts]
TI: Nesting High-resolution Multi-layer Photosynthesis Approaches in Current Forest Productivity Models: A Cost-Benefit Analysis in the Time-Frequency Domain
AU: * Siqueira, M
EM: mbs4@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Duke University Levine Science Research Center, Durham, NC 27708 United States
AU: Katul, G
EM: gaby@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Duke University Levine Science Research Center, Durham, NC 27708 United States
AU: Sampson, D A
EM: dasampso@vt.edu
AF: Department of Forestry, Virginia Tech, 313 Cheatham Hall-0324 Virginia Tech, Blacksburg, VA 24061 United States
AU: Stoy, P
EM: pcs3@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Duke University Levine Science Research Center, Durham, NC 27708 United States
AU: Juang, J
EM: jj19@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Duke University Levine Science Research Center, Durham, NC 27708 United States
AU: Oren, R
EM: ramoren@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Duke University Levine Science Research Center, Durham, NC 27708 United States
AB: Ecosystem processes relevant to carbon transfer and storage are known to vary over many time and space scales. In the time domain, processes ranging from seconds, such as turbulent transport, to seasons, such as plant phenology, affect assimilation and respiration, which in turn, control carbon allocation over time scales of days to years. These inter-related processes contribute to the forest development (often measured in years to decades) and long-term carbon sequestration. To date, no single model captures the entire spectrum of variability of these processes; rather, a modular approach is adopted in which the forcing and response variables are mechanistically coupled over an inherent or assumed time scale that is then integrated to longer time scales. The effect of such modular parameterization of the "fast" processes and their cross-scale interaction with the slowly varying processes on long-term carbon sequestration remains a subject of investigation. We address this problem in two ways. First, we perform a multi-model inter-comparison in the time and frequency domains to assess how different parameterizations of photosynthesis and water vapor fluxes in forest growth models (e.g. BGC, SECRETS, PnET and 3PG) reproduce the observed spectrum of these two fluxes from hours to years. These models were chosen because they significantly vary in complexity and integration time step, thereby "filtering" the flux spectrum differently. Next, we explore the consequences of this filtering on cross-scale information flow using a newly proposed nested scheme that employs multi-species allocation routines with assimilation calculated with CANVEG. CANVEG is a multi-layer and multi-species model that resolves the entire canopy microclimate and uses a dynamic leaf area density as an input. The analysis is done in a cost-benefit fashion evaluating the gain in predictive skills of long-term carbon sequestration as result of extra model complexity and added parameterizations. As a case study, we use multi-year CO2 and water vapor flux measurement from a Pine Plantation at the Duke Forest Ameriflux site.
DE: 1851 Plant ecology
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting