Abstract• The resorption of nutrients (mainly N and P) from senescing leaves may be a key component of adaptive mechanisms that conserve scarce nutrients. Resorption may be expressed in two ways as resorption efficiency (RE) which is the ratio of the resorbed amounts of nutrient losses during leaf senescence in relation to its prior amount deposited in leaves and resorption proficiency (RP) is the level to which nutrient concentration per unit leaf mass is reduced in senescent leaves.• There is still much debate whether or not different life-forms (i.e. deciduous and evergreen species) show different foliar resorption patterns. Two sympatric species, namely Quercus petraea (Mattuschka) Liebl. subsp. iberica (Steven ex Bieb.) Krassiln. (deciduous) and Arbutus andrachne L. (evergreen) along an elevational gradient were compared with each other to determine whether or not nitrogen and phosphorus resorption efficiency and proficiency varies along the elevational gradient and which leaf parameters were as related to RE and RP.• NRE was found to be rather low in Q. petraea subsp. iberica compared to other deciduous species. Similarly, PRE in A. andrachne was rather low compared to other evergreen species. Mean residence time (MRT) measures how long a unit of nitrogen (MRT N ) and phosphorus (MRT P ) is present in the plant. MRT N and MRT P were found to be considerably higher in A. andrachne compared to Q. petraea subsp. iberica. In both species, the foliar N/P ratio was below 14 along the elevational gradient and, according to this threshold value, N-limitation occurred in the study area. Although both species in the present study show incomplete resorption deciduous species was more proficient as compared to evergreen one due to low N and P concentrations in senescent leaves. Based on the significant correlations (p < 0.05 and 0.01) between MRT and foliar resorption, it can be concluded that MRT could interfere with the mechanisms controlling nutrient resorption.Mots-clés : stratégies de Grime / temps moyenne de résidence (MRT) / rapport N/P / efficience de la résorption / capacité de résorption / espèces sympatriques Résumé -Résorption foliaire chez Quercus petraea subsp. iberica et Arbutus andrachne le long d'un gradient altitudinal.• La résorption des éléments nutritifs (essentiellement N et P) par sénescence des feuilles peut être une composante clé des mécanismes d'adaptation qui permettent de conserver les rares éléments nutritifs. La résorption peut être exprimée de deux façons : l'efficience de résorption (RE) qui est le rapport entre la quantité résorbée des pertes d'éléments nutritifs au cours de la sénescence des feuilles par rapport à son montant déposé auparavant dans les feuilles et la capacité de résorption (RP) qui est le niveau auquel la concentration des éléments nutritifs par unité de masse de feuilles est réduite dans les feuilles sénescentes.• Il reste encore beaucoup de débat pour déterminer si les différentes formes de vie (c'est-à-dire les espèces décidues et les espèces sempervirentes) prése...

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-Juniperus oxycedrus L. subsp. macrocarpa (Sibth. & Sm.) Ball occurs in the Mediterranean region, on the southern part of Turkey and has been widely used in landscape planning and stabilization of coastal dunes. In this study foliar N and P resorption and foliar N, P and K concentrations (on a leaf mass basis) were investigated in J. oxycedrus subsp. macrocarpa. Foliar N, P, and K concentrations and absolute and proportional N and P resorption rates along the topographic position were not changed significantly. Significant correlations were found between absolute and proportional P resorption rates and soil moisture status. However, there were no significant correlation between absolute and proportional N resorption rates and soil moisture status. Foliar N and proportional N resorption were significantly correlated although absolute N resorption was not significantly correlated with foliar N. However, foliar P was significantly correlated both absolute and proportional P resorption. Juniperus oxycedrus

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résorption foliaire de l'azote et du phosphore dans une forêt non perturbée et dans une forêt plantée de Pinus pinaster ait. dans le nord de la turquie. -La résorption foliaire est étroitement liée à la sénescence et à la conservation des nutriments et protège la plante dans sa dépendance des apports du sol. Dans la présente étude, ont été étudiées dans le nord-est de la Turquie la dynamique foliaire de l'azote (N) et du phosphore (P), l'efficacité (RE) et la profitabilité (RP) de la résorption foliaire de quelques plantes décidues existant dans une forêt non perturbée et dans une autre plantée en Pinus pinaster Ait. En forêt non perturbée, on n'a pas observé de différences entre les espèces pour ce qui concerne l'efficacité et la profitabilité alors qu'en forêt plantée en P. pinaster des différences statistiquement significatives ont été notées entre les espèces pour ce qui concerne la NRE, la NRP et la CRE. La CRE est apparue plus élevée que chez les angiospermes et graminoïdes ligneux sempervirents présents dans la zone d'étude. La NRE était plus forte en forêt non perturbée qu'en forêt plantée en P. pinaster. Dans les deux forêts la résorption foliaire de l'azote et du phosphore était biochimiquement complète. Il a été trouvé que la limitation en phosphore se produisait dans les plantes décidues des deux forêts au niveau des rapports N/P durant la sénescence foliaire. De même, le rapport C/N s'est avéré élevé durant la sénescence. En forêt plantée en P. pinaster le rapport N/P et la NRE (tant en masse qu'en surface) sont apparus plus faibles qu'en forêt non perturbée.SUmmARY. -Foliar resorption is closely associated with leaf senescence and conservation of nutrients, and protects the plant dependence on soil supply. In this study, leaf nitrogen (N) and phosphorus (P) dynamics, leaf resorption efficiency (RE) and resorption proficiency (RP) in some deciduous plants occurring in an undisturbed forest and a Pinus pinaster Ait. planted forest were investigated in northeastern Turkey. There were no significant differences among species with respect to foliar resorption efficiency and proficiency in undisturbed forest, whilst statistically significant differences were found among species regarding NRE, NRP and CRE in P. pinaster planted forest. CRE was found to be higher than for evergreen woody angiosperms and graminoids present in the study area. NRE was higher in undisturbed forest than in P. pinaster planted forest. In both forests foliar nitrogen and phosphorus resorption were biochemically complete. It was found that phosphorus limitation occurred in deciduous plants in both forests with respect to N/P ratios during leaf senescence. Similarly, C/N ratio was found to be high during senescence. In P. pinaster planted forest N/P ratio and NRE (both mass-and area-based) were found to be low as compared to undisturbed forest.Forests and tree plantations are increasingly considered for their central role as providers of habitat and regulators of global biogeochemical, temperature and water cycles. Forest

IntroductionPlant functional types (PFTs) have been widely proposed as an ecological alternative to classical taxonomy and include easily measurable traits such as life form, leaf habit, plant height, plant longevity, and specific leaf area (SLA). They exhibit similar responses to environmental conditions and also have similar effects on matter and energy processes in ecosystems (Díaz Barradas et al., 1999). PFTs consist of species that have common morphological and physiological attributes, and classification schemes according to PFTs can include the identification of correlations among quantitative traits that reflect life history trade-off or assignment of species to plant functional groups based on dominant traits (Garcia-