2004/11/01 by Sylvain Delzon, S. Delzon, Michel Sartore +5 · 2 citations
Earth and Planetary Sciences · Environmental Science · #Hydrology and Sediment Transport Processes #Plant Water Relations and Carbon Dynamics #Tree-ring climate responses
paper · pdf · doi:10.1093/treephys/24.11.1285
openalex publication_date 2004/11/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
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 (Jref), whereas the other was moved radially across the sapwood in 20-mm increments to measure sap flux at multiple depths (Jref). For all tree sizes, sap flow ratios (Ri = JiJref (-1)) declined with increasing sapwood depth, but the decrease was steeper in trees with large diameters. Correction factors (C) were calculated to extrapolate Jref 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.