HR: 1340h
AN: B33D-1065    [Abstracts]
TI: Vegetative controls on coupled ecosystem water and carbon fluxes on hourly to successional temporal scales
AU: * Stoy, P C
EM: pcs3@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AU: Katul, G G
EM: gaby@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AU: Siqueira, M B
EM: mbs4@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AU: Juang, J
EM: jj19@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AU: Novick, K A
EM: kan2@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AU: Oren, R
EM: ramoren@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, A328 LSRC, Durham, NC 27708
AB: We use long-term eddy covariance data from a novel field experiment in adjacent grass, pine, and hardwood ecosystems to investigate the degree of coupling between carbon and water fluxes at time scales from hours to years. The experimental setup is a model of post-agricultural ecosystem succession in the SE U.S. and can thus give insight into carbon / water relationships across time scales of ecosystem development. We demonstrate that carbon cycling is sensitive to both the state (via soil moisture) and flux of water. However, variability in the water cycle 'resonates' with net ecosystem carbon exchange of carbon (NEE) at different time scales across the various vegetation types as detected by a wavelet analysis. We demonstrate that these time scales reflect the seasonality of the vegetation as well as their sensitivity to drought and extreme events. The magnitude of the immediate and lagged responses of carbon and water cycling to severe drought and ice storm events is further quantified via a linear perturbation analysis of simple ecosystem models. The combination of flux data, nonlinear time series analysis, and ecosystem model analysis demonstrates that the carbon and water cycles became progressively decoupled along the grass - pine - hardwood successional trajectory. Thus, recent management trends toward increasing the landcover area of pine plantations at the expense of hardwood forests in the SE U.S. may increase the sensitivity of regional carbon cycling to hydrologic perturbations.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 1813 Eco-hydrology
DE: 1818 Evapotranspiration
SC: Biogeosciences [B]
MN: Fall Meeting 2005