Response of Pinus sylvestris L. to recent climatic events in the French Mediterranean regionReport as inadecuate




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1 UR EMAX - Ecosystèmes méditerranéens et risques 2 IMEP - Institut Méditerranéen d-Ecologie et de Paléoécologie 3 UMR AMAP - Botanique et Bioinformatique de l-Architecture des Plantes

Abstract : Exceptional climatic events from 2003 to 2005 scorching heat and drought affected the whole of the vegetation in the French Mediterranean region and in particular Scott pines Pinus sylvestris L., one of the most important forest tree species in this area. To understand its response to these extreme conditions, we investigated its radial growth, branch length growth, architectural development and reproduction for the period 19952005, and linked these variables to climatic parameters. We used four plots situated in southeastern France and presenting different levels of site quality and potential forest productivity. The results show that: 1 the climatic episode 20032005 was highly detrimental to the growth bole and branches, crown development, and cone production but favoured the production of male flowers; 2these variables depend on climatic factors of both the current and previous years; 3 the 2003 scorching heat impact was strong but was mainly apparent from 2004; it was part of a 6-year-long unfavourable cycle beginning in 2000, characterized by high minimum and maximum temperatures and very dry springs;4 in spite of a significant effect of site quality, the Scots pine-s response to extreme climatic conditions was homogeneous in the French Mediterranean area; and 5 the stress induced by poor site conditions generally resulted in the same consequences for tree growth, architecture, and reproduction as in unfavourable climatic conditions.

Résumé : Des événements climatiques exceptionnels de 2003 à 2005 canicule et sécheresse ont affecté la végétation dans la région de la Méditerranée française et en particulier le pin sylvestre Pinus sylvestris L., une des principales essences forestières de cette région. Pour comprendre sa réponse à ces conditions extrêmes, nous avons examiné sa croissance radiale, la croissance en longueur des branches, le développement architectural et la reproduction pendant la période 1995-2005 et avons relié ces variables avec les paramètres climatiques. Nous avons utilisé quatre placettes situées dans le sud-est de la France et présentant des niveaux différents de qualité stationnelle et de productivité forestière potentielle. Les résultats montrent que : 1 l-épisode climatique 2003-2005 était fortement néfaste à la croissance tronc et branches, au développement du houppier et à la production de cônes, mais a favorisé la production de fleurs mâles; 2 ces variables dépendent des facteurs climatiques des années en cours et précédente; 3 l-impact de canicule 2003 était fort, mais était principalement apparent de 2004; il faisait partie d-un cycle défavorable de 6 ans commençant en 2000, caractérisé par des hautes températures minimales et maximales et des printemps très secs; 4 malgré un effet significatif de la qualité stationnelle, la réponse du pin sylvestre aux conditions climatiques extrêmes était homogène dans la zone méditerranéenne française; Et 5 le stress provoqué par de mauvaises conditions stationnelles avait généralement les mêmes conséquences pour la croissance , l-architecture et la reproduction du pin sylvestre que des conditions climatiques défavorables. - Exceptional climatic events from 2003 to 2005 scorching heat and drought affected the whole of the vegetation in the French Mediterranean region and in particular Scott pines Pinus sylvestris L., one of the most important forest tree species in this area. To understand its response to these extreme conditions, we investigated its radial growth, branch length growth, architectural development and reproduction for the period 19952005, and linked these variables to climatic parameters. We used four plots situated in southeastern France and presenting different levels of site quality and potential forest productivity. The results show that: 1 the climatic episode 20032005 was highly detrimental to the growth bole and branches, crown development, and cone production but favoured the production of male flowers; 2these variables depend on climatic factors of both the current and previous years; 3 the 2003 scorching heat impact was strong but was mainly apparent from 2004; it was part of a 6-year-long unfavourable cycle beginning in 2000, characterized by high minimum and maximum temperatures and very dry springs;4 in spite of a significant effect of site quality, the Scots pine-s response to extreme climatic conditions was homogeneous in the French Mediterranean area; and 5 the stress induced by poor site conditions generally resulted in the same consequences for tree growth, architecture, and reproduction as in unfavourable climatic conditions.

Mots-clés : PINUS SYLVESTRIS CHANGEMENT CLIMATIQUE CANICULE SECHERESSE RESISTANCE A LA SECHERESSE CROISSANCE EN VOLUME CROISSANCE EN HAUTEUR ARCHITECTURE DE L-ARBRE DENDROMETRIE REPRODUCTION





Author: A. Thabeet - M. Vennetier - C. Gadbin-Henry - N. Denelle - M. Roux - Y. Caraglio - B. Vila -

Source: https://hal.archives-ouvertes.fr/



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