La végétation de l'étage subalpin du bassin supérieur de la Tinée (Alpes- Maritimes) Application de l'analyse multidimensionelle aux données floristiques Première Partie
This study of a high valley of the French maritime Alps demonstrates the value of some modern numerical methods in the field of phytosociology and also explains the vegetation of a belt for which existing data remained very fragmentary, chiefly in the austro-occidental Alps. The first part shows the application of factor analysis 10 the sorting out of floristical stands done in the studied territory (matrix of 295 stands X 503 species) and the definition of a methodology which permits, by multidimensional analysis of only floristical characters, to individualize and characterize the plant associations. This analysis exhibits a dozen main types of plant communities which correspond generally to higher units of the phytosociological hierarchy and 10 well characterized habitats. Then each type is subjected 10 a new numerical treatment which results in a fine determination of the plant associations. This method leads to individualization of 28 plant communities representing associations or subassociations, the majority of which are original. Their detailed analysis is treated in the second part. Each community is looked upon from three points of view: floristical and phytosociological characters, ecological and dynamical characters, distribution and affinities in the Alps and in the other mountain groups (the Pyrenees and the Balkans). The study results in a synthetic picture of the subalpine vegetation dynamics in this region, dynamics which terminates with the settlement in the upper part of the subalpine belt of a phytoclimax differentiated in two sub-units according 10 the substratum because of climatic characters which do not permit the formation, from different substratum, of soils really similar. On the other hand, this study exposes, after comparison with the great phytogeographical units of alpine mountain chain, the origin of plant communities grown in the territory and emits its original position, intermediate between the prealpine and the intra-alpine zone.