Whole-stem water relations in white oak (Quercus alba L.)
Goranson, Carol Elaine
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While many tree species rely on sapwood capacitance to store and release water for transpiration, heartwood has never been considered to be a water storage reservoir. This research project investigated diurnal and seasonal changes in heartwood water content of white oak (Quercus alba (L.)) using automated TDR probes, and related the results to tree water use, measured using sap flux sensors, and environmental variables. Sap flux data were recorded from June to November, 2004, and heartwood water content was monitored from June 2004 to May 2005. Q. alba heartwood had daily and seasonal water content fluctuations that were correlated with temperature and the availability of soil moisture, but the daily heartwood water loss was not correlated with tree water use. Water is stored in and released from the heartwood of Q. alba, but heartwood water loss seems driven by environmental factors more than tree water use.