Plant and Soil

, Volume 282, Issue 1, pp 361–378

Hydraulic Lift in Cork Oak Trees in a Savannah-Type Mediterranean Ecosystem and its Contribution to the Local Water Balance

Authors

    • Instituto Superior de Agronomia
  • Dennis Otieno
    • Department of Plant EcologyUniversity of Bayreuth
  • Raquel Lobo do Vale
    • Instituto Superior de Agronomia
  • Rolf Siegwolf
    • Laboratory of Atmospheric ChemistryPaul Scherrer Institute
  • Markus Schmidt
    • Department of Plant EcologyUniversity of Bayreuth
  • Alastair Herd
    • Instituto Superior de Agronomia
  • Carla Nogueira
    • Instituto Superior de Agronomia
  • Teresa Soares David
    • Estação Florestal NacionalINIAP
  • Jorge Soares David
    • Instituto Superior de Agronomia
  • John Tenhunen
    • Department of Plant EcologyUniversity of Bayreuth
  • João Santos Pereira
    • Instituto Superior de Agronomia
  • Manuela Chaves
    • Instituto Superior de Agronomia
    • Instituto de Tecnologia Química e Biológica
Article

DOI: 10.1007/s11104-006-0005-4

Cite this article as:
Kurz-Besson, C., Otieno, D., Lobo do Vale, R. et al. Plant Soil (2006) 282: 361. doi:10.1007/s11104-006-0005-4

Abstract

The aim of this study was to identify the sources and depth of water uptake by 15-years old Quercus  suber L. trees in southern Portugal under a Mediterranean climate, measuring δ18O and δD in the soil–plant-atmosphere continuum. Evidence for hydraulic lift was substantiated by the daily fluctuations observed in Ψs at 0.4 and 1 m depth and supported by similar δ18O values found in tree xylem sap, soil water in the rhizosphere and groundwater. From 0.25 m down to a depth of 1 m, δD trends differed according to vegetation type, showing a more depleted value in soil water collected under the evergreen trees (−47‰) than under dead grasses (−35‰). The hypothesis of a fractionation process occurring in the soil due to diffusion of water vapour in the dry soil is proposed to explain the more depleted soil δD signature observed under trees. Hydraulically lifted water was estimated to account for 17–81% of the water used during the following day by tree transpiration at the peak of the drought season, i.e., 0.1–14 L tree−1 day−1. Significant relationships found between xylem sap isotopic composition and leaf water potential in early September emphasized the positive impact of the redistribution of groundwater in the rhizosphere on tree water status.

Keywords

δ18Ohydraulic liftQuercus  suberroot biomasssoil δD fractionationsoil water potential

Abbreviations

hydraulic lift

(HL)

leaf water potential

L)

soil temperature

(TS)

soil water content

(SWC)

soil water potential

S)

vapour pressure deficit

(VPD)

tree transpiration

(E)

Copyright information

© Springer 2006