HR: 14:25h
AN: H42H-04    [PDF]
TI: Ecosystem Water and Carbon States: A Dynamical Systems View
AU: * Katul, G G
EM: gaby@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AU: Oren, R
EM: ramoren@duke.ed
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AU: Stoy, P
EM: pcs3@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AU: Siqueira, M
EM: mbs4@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AU: McCarthy, H
EM: heather.McCarthy@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AU: Juang, J
EM: jj19@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Levine Science Research Center Box 90328, Duke University, Durham, NC 27708-0328 United States
AB: To quantify the "resilience" of ecosystems to climate fluctuations, a two-state model linking carbon and water reservoirs is developed. The model is forced by climate variables such as radiative and precipitation input, air temperature, atmospheric water vapor and CO2 concentrations. The model is first tested using 5 years of water vapor and CO2 flux measurements along with moisture content collected every 30 minutes, and net primary productivity measurements collected throughout the growing seasons in a managed pine forest near Durham, North Carolina. We show that traditional concepts from dynamical systems theory applied to equilibrium states is not useful to quantifying stability and resilience of ecosystems to climate perturbations. It is shown that such an ecosystem, defined by the water-carbon stores, is influenced by processes and excursions far from equilibrium, experience multiple equilibrium points or loss of equilibrium altogether. However, a methodology that utilizes the coherency in trajectory at the extremes of the carbon and water stores in phase-space still provides adequate measures of ecosystem resilience. Mechanisms by which elevated atmospheric CO2 alters such resilience are also discussed.
DE: 0315 Biosphere/atmosphere interactions
DE: 1615 Biogeochemical processes (4805)
DE: 1851 Plant ecology
DE: 1878 Water/energy interactions
SC: Hydrology [H]
MN: 2003 Fall Meeting