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Title:
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A retrospective, dual-isotope approach reveals individual predispositions to winter-drought induced tree dieback in the southernmost distribution limit of Scots pine
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Author:
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Voltas Velasco, Jordi; Camarero Martínez, Jesús Julio; Carulla Montañés, David; Aguilera, Mònica; Ortiz, Araceli; Ferrio Díaz, Juan Pedro
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Notes:
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Winter-drought induced forest diebacks in the low-latitude
margins of species’ distribution ranges can provide new
insights into the mechanisms (carbon starvation, hydraulic
failure) underlying contrasting tree reactions.We analysed a
winter-drought induced dieback at the Scots pine’s southern
edge through a dual-isotope approach (D13C and d18O in treering
cellulose).We hypothesized that a differential long-term
performance, mediated by the interaction between CO2 and
climate, determined the fates of individuals during dieback.
Declining trees showed a stronger coupling between climate,
growth and intrinsic water-use efficiency (WUEi) than nondeclining
individuals that was noticeable for 25 years prior to
dieback. The rising stomatal control of water losses with time
in declining trees, indicated by negative D13C-d18O relationships,
was likely associated with their native aptitude to grow
more and take up more water (suggested by larger tracheid
lumen widths) than non-declining trees and, therefore, to
exhibit a greater cavitation risk. Freeze-thaw episodes occurring
in winter 2001 unveiled such physiological differences by
triggering dieback in those trees more vulnerable to hydraulic
failure. Thus, WUEi tightly modulated growth responses
to long-term warming in declining trees, indicating that
co-occurring individuals were differentially predisposed to
winter-drought mortality. These different performances were
unconnected to the depletion of stored carbohydrates.
This work was partially supported by the DGI projects CGL2009-13079-C02-01 and CGL2011-26654 and grant FP7- PEOPLE-2009-RG-246725 (SMARTREES). We acknowledge R. Hernández, M. Maestro, V. Pérez-Fortea and P. Sopeña for field and technical assistance. J.P.F. is supported by a postdoctoral contract from the ‘Ramon y Cajal’ programme (MCINN). |
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Subject(s):
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-Pinus sylvestris
-Stable isotopes
-Water-use efficiency |
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Rights:
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(c) John Wiley & Sons Ltd, 2013
info:eu-repo/semantics/restrictedAccess |
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Document type:
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article
publishedVersion |
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Published by:
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John Wiley & Sons Ltd
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