Whole-tree water use in 4- and 8-year-old plantations of Eucalyptus nitens Deane and Maiden (ex Maiden) in the presence and absence of Acacia dealbata Link. weeds was estimated by the heat pulse velocity technique during a six-week summer period. Maximum sap velocities were recorded between 5 and 15 mm under the cambium for both eucalypt and acacia trees, and marked radial and axial variations in sap velocity were observed. The latter source of variation was most pronounced in mixed stands where crowns were asymmetrical. Mean daily sap flux ranged from 1.4 to 103.6 l day⁻¹ for eucalypts and from < 0.1 to 8.4 l day⁻¹ for acacias. Stem diameter explained 98% of the variation in sapwood area for E. nitens and 89% for A. dealbata, and was determined to be a suitable parameter for scaling water use from the tree to stand level. Plot transpiration varied from 1.4 to 2.8 mm day⁻¹ in mixed 8-year-old plots and was 0.85 mm day⁻¹ in a mixed 4-year-old plot. The degree of A. dealbata infestation was associated with absolute plot water use and regression models predicted that, in the absence of acacia competition, plot water use for the 8-year-old stand would approach 5–6 mm day⁻¹ during the growing season.

Item Type:	Refereed Article
Keywords:	competition, eucalypts, heat pulse, sap flux, scaling
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Forestry sciences
Research Field:	Tree nutrition and physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Hardwood plantations
UTAS Author:	Hunt, MA (Professor Mark Hunt)
UTAS Author:	Beadle, CL (Dr Christopher Beadle)
ID Code:	102751
Year Published:	1998
Web of Science® Times Cited:	24
Deposited By:	Plant Science
Deposited On:	2015-09-04
Last Modified:	2015-10-06
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