Analyse de la flore des Alpes. 4: Écologie (original) (raw)

The fourth in a series, this paper continues the statistical analysis of the data published in "Flora Alpina", treating that which concerns the ecology: preferred substrate and indicator values of the soil (humidity and trophic level). Expressed as percentages, the results concerning the flora are envisaged globally, by vegetation belt, by administrative division, by floristic contingent, by family, by genus and by biological form. Among the 4485 taxa studied in the Alps, a xerophilous, calcicole and oligotrophic tendency is prominent. Within the endemics, this trend is clearly more pronounced and, moreover, they are mostly stenoecious for the substrate, because they are often in extreme habitats where edaphic determinism is considerable. On the other hand, the profile of the xenophytes is more balanced: mesophilous, euryoecious for the substrate and meso-eutrophic (even eurytrophic). These ecological tolerances confer an important potential for colonization on the xenophytes. The correlations between factors are also studied and it is shown, for example, that the xerophilous taxa tend to be oligotrophic, whereas hygrophilous ones tend to be eutrophic.