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Eur J Forest Res (2008) 127:369378 DOI 10.1007/s10342-008-0214-x
ORIGINAL PAPER
Response of Quercus pyrenaica (melojo oak) to soil water deWcit: a case study in Spain
Virginia Hernndez-Santana
Jos Martnez-Fernndez Carlos Morn Ana Cano
Received: 21 September 2007 / Revised: 14 March 2008 / Accepted: 16 April 2008 / Published online: 14 May 2008 Springer-Verlag 2008
Abstract In the present study, carried out from 2004 to 2006, leaf and stem water potential and stem water content were measured in Quercus pyrenaica Willd. individuals in an experimental forested catchment located in Central Western Spain under Mediterranean subhumid conditions. These indicators of tree water status were compared with soil moisture contents measured in the same area from 0 to 1 m depth and from 0 to 2.5 m depth during the last year of the study. The objectives were to clarify the seasonal and year-to-year variations in tree water status, to examine applicability of stem water content as useful water stress indicator and to discuss how deep soil water and root uptake contribute to survival during the long dry summer. Seasonal variations in the tree variables measured revealed a typical pattern, with maximum values at the end of spring followed by a progressive decline during the summer drought in response to the decrease in soil water content (almost exhausted at 0100 cm depth). The relatively high values and the non-signiWcant variation in predawn leaf water potentials (except for 2005, which was exceptionally dry) indicate that no clear water stress situations occurred. This may be explained in terms of a progressive absorption of water from the deeper layers. The results also suggest
that the stem water content is a more sensitive indicator of long-term water limitation than the other variables measured.
Keywords Leaf water potential Mediterranean oaks Soil water content Stem water content Stem water potential
Introduction
Water-controlled ecosystems are complex and involve structures whose characteristics and dynamic properties depend on many interrelated links between climate, soil, and vegetation. Plants have a special role in this kind of ecosystem, playing an active role in water use that strongly aVects the water balance. At the same time the soil water depletion, caused by plant water use, has negative consequences on tree water status (Rodrguez-Iturbe and Porporato 2005).
In Mediterranean areas,...