Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands

Publication Type:Journal Article
Year of Publication:2002
Authors:A. Kremer, Dupouey, J., Deans, J., Cottrell, J., Csaikl, U., Finkeldey, R., Espinel, S., Jensen, J., Kleinschmit, J., Van Dam, B., Ducousso, A., Forrest, I., U. de Heredia, L., Lowe, A., Tutkova, M., Munro, R., Steinhoff, S., Badeau, V.
Journal:Annals of Forest Science
Date Published:2002

Leaf morphology was assessed in nine mixed oak stands (Quercus petraea and Q. robur) located in eight European countries.Exhaustive sampling was used in an area of each stand where the two species coexisted in approximately equal proportions (about 170 trees/species/ stand). Fourteen leaf characters were assessed on each of 5 to10 leaves collected from the upper part of each tree. Three multivariate statistical techniques (CDA, canonical discriminant analysis; PCA, principal component analysis; MCA, multiple correspondence analysis) were used in two different ways: first on the total set of leaves over all stands (global analysis) and second, separately within each stand (local analysis). There was a general agreement of the results among the statistical methods used and between the analyses conducted (global and local). The first synthetic variable derived by each multivariate analysis exhibited a clear and sharp bimodal distribution, with overlapping in the central part. The two modes were interpreted as the two species, and the overlapping region was interpreted as an area where the within-species variations were superimposed. There was no discontinuity in the distribution or no visible evidence of a third mode which would have indicated the existence of a third population composed of trees with intermediate morphologies. Based on petiole length and number of intercalary veins, an

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