biology

Author(s): Delzon S, Sartore M, Granier A, Loustau D

Source: TREE PHYSIOLOGY 24 (11): 1285-1293 NOV 2004

Document Type: Article

Language: English

Abstract: We investigated the radial variation of sap flow within sapwood below the live crown in relation to tree size in 10-, 32-, 54- and 91-year-old maritime pine stands (Pinus pinaster Ait.). Radial variations were determined with two thermal dissipation sensors; one measured sap flux in the outer 20 mm of the xylem (J(ref)), whereas the other was moved radially across the sapwood in 20-mm increments to measure sap flux at multiple depths (J(i)). For all tree sizes, sap flow ratios (R-i = J(i)J(ref)(-1))declined with increasing sapwood depth, but the decrease was steeper in trees with large diameters. Correction factors (C) were calculated to extrapolate J(ref) for an estimate of whole-tree sap flux. A negative linear relationship was established between stem diameter and C, the latter ranging from 0.6 to 1.0. We found that neglecting these radial corrections in 10-, 32-, 54- and 91-year-old trees would lead to overestimation of stand transpiration by 4, 14, 26 and 47%, respectively. Therefore, it is necessary to account for the differential radial profiles of sap flow in relation to tree size when comparing tree transpiration and hydraulic properties among trees differing in size.

Author Keywords: correction factor; heat dissipation method; Pinus pinaster; sap flux; tree size effect

KeyWords Plus: HEAT PULSE VELOCITY; FOREST CANOPY TREES; WATER-VAPOR FLUX; STAND TRANSPIRATION; SAPFLOW VELOCITY; CANARY-ISLANDS; SPRUCE TREES; SCOTS PINE; CONDUCTANCE; SAPWOOD

Addresses: Delzon S (reprint author), INRA, Unite EPHYSE, 69 Route Arcachon, F-33612 Gazinet France
INRA, Unite EPHYSE, F-33612 Gazinet France
Univ Nancy 1, INRA, UMR, Lab Ecol & Ecophysiol Forestieres, F-54280 Seichamps France

E-mail Addresses: delzon@pierroton.inra.fr

Publisher: HERON PUBLISHING, 202, 3994 SHELBOURNE ST, VICTORIA, BC V8N 3E2, CANADA, http://www.heronpublishing.com

Discipline: PLANT SCIENCES

CC Editions/Collections: Agriculture, Biology & Environmental Sciences (ABES)

IDS Number: 869GF