Balancing the risks of hydraulic failure and carbon starvation : a twig scale analysis in declining Scots pine
Salmon, Yann (University of Edinburgh. School of GeoSciences)
Torres-Ruiz, José M. (Institut National de la Recherche Agronomique (França))
Poyatos, Rafael (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Martínez Vilalta, Jordi, 1975- (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)
Meir, Patrick (University of Edinburgh. School of GeoSciences)
Cochard, Hervé (Institut National de la Recherche Agronomique (França))
Mencuccini, Maurizio (University of Edinburgh. School ofGeoSciences)

Data:	2015
Resum:	Understanding physiological processes involved in drought-induced mortality is important for predicting the future of forests and for modelling the carbon and water cycles. Recent research has highlighted the variable risks of carbon starvation and hydraulic failure in drought-exposed trees. However, little is known about the specific responses of leaves and supporting twigs, despite their critical role in balancing carbon acquisition and water loss. Comparing healthy (non-defoliated) and unhealthy (defoliated) Scots pine at the same site, we measured the physiological variables involved in regulating carbon and water resources. Defoliated trees showed different responses to summer drought compared with non-defoliated trees. Defoliated trees maintained gas exchange while non-defoliated trees reduced photosynthesis and transpiration during the drought period. At the branch scale, very few differences were observed in non-structural carbohydrate concentrations between health classes. However, defoliated trees tended to have lower water potentials and smaller hydraulic safety margins. While non-defoliated trees showed a typical response to drought for an isohydric species, the physiology appears to be driven in defoliated trees by the need to maintain carbon resources in twigs. These responses put defoliated trees at higher risk of branch hydraulic failure and help explain the interaction between carbon starvation and hydraulic failure in dying trees.
Ajuts:	Ministerio de Ciencia e Innovación CSD2008-00040 Ministerio de Ciencia e Innovación CGL2010-16373
Nota:	Acknowledgments: part of this work were supported by an STSMGrant from COST Action FP1106 (STReESS)
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Drought ; Ecophysiology ; Leaf gas exchange ; Mortality ; NSC ; Photosynthesis ; Transpiration ; Tree
Publicat a:	Plant, cell & environment, Vol. 38, Issue 12 (Dec. 2015) , p. 2575-2588, ISSN 1365-3040

DOI: 10.1111/pce.12572
PMID: 25997464

14 p, 747.8 KB

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