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Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna


Eamus, D and Hutley, LB and O'Grady, AP, Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna, Tree Physiology, 21, (12-13) pp. 977-988. ISSN 0829-318X (2001) [Refereed Article]

DOI: doi:10.1093/treephys/21.12-13.977


Daily and seasonal fluxes of carbon dioxide and water vapor above a north Australian savanna were recorded over a complete dry season-wet season annual cycle using the eddy covariance technique. Wet season rates of photosynthesis and transpiration were larger than those measured in the dry season and were dominated by the presence of the grassy understory. As the dry season progressed and the grass understory died, ecosystem rates of assimilation and water vapor flux declined substantially. By the end of the dry season, canopy assimilation and evapotranspiration rates were 20-25% of wet season values. Assimilation was light saturated in the dry season but not in the wet season. Stomatal control of transpiration increased between the wet and dry season. This was revealed by the decline in the slope of E with increasing leaf-to-air vapor pressure difference (D) between wet and dry seasons, and also by the significant decrease in the ratio of boundary to canopy conductance observed between the wet and dry seasons. A simple pan-tropical modeling of leaf area index or wet season canopy CO 2 flux was undertaken. It was shown that with readily available data for foliar N content and the ratio of rainfall to potential evaporation, leaf index and wet season canopy CO 2 flux can be successfully estimated for a number of tropical ecosystems, including north Australian savannas.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant pathology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Forestry
Objective Field:Native forests
UTAS Author:O'Grady, AP (Dr Anthony O'Grady)
ID Code:48183
Year Published:2001
Web of Science® Times Cited:115
Deposited By:Plant Science
Deposited On:2007-10-23
Last Modified:2011-08-03

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