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

Eamus, D, Hutley, LB and O'Grady, AP (2001). Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna. Tree Physiology,21:977-988.

Document type: Journal Article
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Title Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna
Author Eamus, D
Hutley, LB
O'Grady, AP
Journal Name Tree Physiology
Publication Date 2001
Volume Number 21
ISSN 0829-318x   (check CDU catalogue open catalogue search in new window)
Start Page 977
End Page 988
Total Pages 12
Place of Publication Victoria, Canada
Publisher Heron Publishing
HERDC Category C1 - Journal Article (DEST)
Abstract 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 CO2 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 CO2 flux can be successfully estimated for a number of tropical ecosystems, including north Australian savannas.
Keywords eddy covariance
vapor-pressure deficit
stomatal responses
eddy covariance
tropical savanna
leaf phenology
dry season
wet season
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Created: Fri, 12 Sep 2008, 08:35:25 CST by Administrator