Response of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) to soil and atmospheric water deficits under Mediterranean mountain climate

Abstract

. Response of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) to soil and atmospheric water deficits under Mediterranean mountain climate. Annals of Forest Science, Springer Verlag/EDP Sciences, 2008, 65 (3), pp.1. <hal-00883386>Ann. For. Sci. 65 (2008) Abstract -The physiological responses to water deficits of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) were studied under Mediterranean mountain climate. Minimum leaf water potentials were −3.2 MPa for oak and −2.1 MPa for pine, with higher predawn values for pubescent oak. Relative sap flow declined in both species when vapour pressure deficit (D) went above ca. 1.2 kPa, but stomatal control was stronger for pine during the 2003 summer drought. P. sylvestris plant hydraulic conductance on a half-total leaf area basis (k L, s−l ) was 1.2-2.6 times higher than the values shown by Q. pubescens, and it showed a considerably steeper decrease during summer. Leaf-level gas exchange was positively related to k L, s−l in both species. Scots pine was more vulnerable to xylem embolism and closed stomata to prevent substantial conductivity losses. The results of this study confirm that pubescent oak is more resistant to extreme drought events.canopy stomatal conductance / drought / hydraulic conductance / Mediterranean climate / sap flow Résumé -Réponses du pin sylvestre (Pinus sylvestris L.) et du chêne pubescent (Quercus pubescens Wild.) aux déficits hydriques atmosphérique et édaphique sous climat montagnard méditerranéen. Les réponses physiologiques aux déficits hydriques du pin sylvestre (Pinus sylvestris L.) et du chêne pubescent (Quercus pubescens Wild.) ont été étudiées sous climat montagnard méditerranéen. Le potentiel hydrique foliaire minimum atteint a été de −3,2 MPa pour le chêne et de −2,1 MPa pour le pin, avec des valeurs de potentiel de base plus élevées pour le chêne pubescent. Un relatif déclin du flux de sève a été observé chez les deux espèces lorsque le déficit de vapeur d'eau dépassait 1,2 kPa, mais le contrôle stomatique a été plus fort chez le pin pendant la sécheresse de l'été 2003. La conductance hydraulique des pins, ramenée à la surface foliaire (k L, s−1 ) a été de 1,2 à 2,6 fois plus élevée que celle de Quercus pubescens et a présenté une rapide décroissance pendant l'été. Le niveau des échanges gazeux foliaires était positivement corrélé à k L, s−1 chez les deux espèces. Le pin sylvestre est plus vulnérable à l'embolie du xylème et a de ce fait fermé ses stomates pour empêcher une perte substantielle de conductivité hydraulique. Les résultats de cette étude confirment que le chêne pubescent est plus résistant aux épisodes d'extrême sécheresse que le pin sylvestre.conductance stomatique du couvert / sècheresse / conductance hydraulique / climat méditerranéen / flux de sève

Combining remote sensing and GIS climate modelling to estimate daily forest evapotranspiration in a Mediterranean mountain area

“…They compared their results with estimates from the literature due to the difficulty in validating these kinds of regions using sap flow measurements. Nagler et al (2005Nagler et al ( , 2007 (Poyatos et al, 2008). However, in the case of MODIS ET d modelling, the validation shows a higher RMSE, which suggests that higher spatial resolution is needed for heterogeneous areas.…”

“…Instantaneous values (15-min averages) were then summed to compute daily stand transpiration. Further details on the methodology and results of sap flow measurements used in this study can be found in Poyatos et al (2005Poyatos et al ( , 2008.…”

Seasonal changes in the physiological activity of regeneration under a natural light gradient in a Pinus pinea regular stand

“…The difference between Ψ pd and Ψ md (|Ψ md -Ψ pd |) increased with decreasing Ψ pd , therefore allowing a greater increase in the driving force for transpiration as edaphic drought developed (Poyatos et al, 2008). A decrease of seedling water potential affected negatively to stomatal conductance and net assimilation rate during summer drought, irrespective of age class.…”

An improved species distribution model for Scots pine and downy oak under future climate change in the NW Italian Alps

“…The response of downy oak to climate warming was different from Scots pine and produced an increased probability of occurrence throughout the study region. Previous research has demonstrated that downy oak is better adapted than Scots pine to both short-and long-term drought, due to its different physiological responses, i.e., stomata closure, resistance to embolism, and seedling vitality (Eilmann et al 2006;Poyatos et al 2008;Morán-López et al 2012).…”