Elevation and Topography Affect Floristic Diversity, Endemism and Functional Traits on Mount Hermon, Lebanon

Résumé fourni par la source

How elevation and topography structure floristic diversity, endemic plant distribution, life-form composition, and taxonomic filtering remains poorly documented for the Levantine ranges of the Eastern Mediterranean, where explicit ecological hypotheses have not been tested. We surveyed 169 plots (1067–2436 m) on the western slopes of Mount Hermon (Lebanon), a protected mountain, using Canonical Correspondence Analysis and nonparametric tests to compare species composition, diversity, endemism, life-form, and family-level metrics among three bioclimatic belts (supra-, oro-, and cryoro-Mediterranean). Although the six predictors explained 10% of total floristic variation, elevation and temperature jointly dominated the ordination, with precipitation, slope, and aspect contributing independent effects. Species richness and alpha diversity declined with elevation while beta diversity increased, driven by species replacement between belts. Endemism responses depended on geographic scale: endemism rate increased while Eastern Mediterranean endemism declined with elevation. Life-form composition shifted markedly, with phanerophytes and therophytes giving way to hemicryptophytes and thorny chamaephytes at high elevation. Woody species assemblages showed the strongest compositional response to elevation, with relict deciduous woodland specialists of the oro-Mediterranean belt among the most conservation-sensitive taxa identified. Family-level composition responded only weakly to elevation, demonstrating scale dependence of elevational filtering. Our results provided floristic baseline for conservation in Mount Hermon’s newly established nature reserve.

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