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Water relations of black spruce trees on a peatland during wet and dry years

Pepin, Steeve ; Plamondon, André ; Britel, Abderraouf

In: Wetlands, 2002, vol. 22, no. 2, p. 225-233

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    Titre
    • Water relations of black spruce trees on a peatland during wet and dry years
    Auteur
    • Pepin, Steeve. Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056, Basel, Switzerland
    • Plamondon, André. Centre de recherche en biologie forestière Département des sciences du bois et de la forêt Faculté de foresterie et de géomatique, Université Laval, G1K 7P4, Sainte-Foy, Québec, Canada
    • Britel, Abderraouf. Service des Eaux et Forêts, B.P. 405, Tanger, Maroc
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:322571
    Summary
    Low water tables typically found in peatlands during dry summer periods or in the vicinity of drainage ditches may lead to moisture deficiency in porous surface peats. Episodes of drought stress might compromise the growth benefits brought about by lower ground-water levels. We examined the water relations of black spruce (Picea mariana) trees on a natural peatland during relatively wet (1990) and relatively dry (1991) summers. Seasonal patterns of pre-dawn and mid-day shoot water potentials and stomatal conductance were not related to peat water content or to water-table depth. There was no evidence of water stress or osmotic adjustment in sampled trees during wet and dry growing seasons. Our soil moisture data showed that although water-table levels were as low as −66 cm in 1991, water availability in the root zone remained high. Even with the absence of mid-day water stress during the summer of 1991, a 50% reduction in stomatal conductance as compared with the previous year was found. We suggest that signals from the bulk of the roots located in dry peat top layer contributed to the regulation of stomatal conductance