Environmental Controls on Water Use Efficiency during Severe Drought in an Ozark Forest in Missouri, USA

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Global Change Biology

DOI:https://doi.org/10.1111/j.1365-2486.2009.02138.x· OSTI ID:982720

Yang, Bai ^[1]; Pallardy, Stephen G. ^[2]; Meyers, T. P. ^[3]; Gu, Lianhong ^[1]; Hanson, Paul J ^[1]; Wullschleger, Stan D ^[1]; Heuer, Mark ^[4]; Hosman, K. P. ^[2]; Riggs, Jeffery S ^[1]; Sluss, Daniel Wayne ^[1]

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1. ORNL
2. University of Missouri
3. NOAA ATDD
4. ATDD, NOAA

Environmental control of canopy-level water use efficiency (WUE) during drought was studied at an eddy flux site in an oak-hickory forest in central Missouri, USA. Two consecutive severe droughts in the summers of 2006 and 2007 afforded coverage of a broad range of environmental conditions. We stratified data so as to obtain sub-ranges that minimized cross-correlations among WUE-controlling factors. Our results showed that WUE was subject to control by atmospheric vapor pressure deficit (VPD), soil water potential (SWP) and the ratio of diffuse to total photosynthetically active radiation (If/It). The relationship between WUE and VPD was found to be an exponential decay function, whereas SWP and If/It appeared to control WUE in a linear fashion. VPD was a stronger controller than the other two factors since the former had much better correlations with WUE. It was also observed that the relationship between WUE and any single controlling factor was subject to regulations by the other two. One such example was an opposite response of WUE to SWP between low and high VPD values. An examination of WUE-SWP relationship within the full range of VPD obscured this difference. We also found that the slope of the linear regression between WUE and If/It, if determined within the full range of VPD, was exaggerated in comparison to that obtained in the sub-ranges of VPD. This was attributable to the fact that the two controlling parameters, VPD and If/It, were themselves correlated and direct controls of VPD on WUE were partially reflected in WUE-If/It relationship if considered within the full range of VPD.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 982720
• Journal Information: Global Change Biology, Vol. 16, Issue 8; ISSN 1354-1013
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
DECAY
DROUGHTS
EFFICIENCY
FORESTS
MISSOURI
RADIATIONS
REGULATIONS
SOILS
VAPOR PRESSURE
WATER
WATER USE