The High Mountain Flora and Vegetation

Abstract

The orophile flora of the Iberian Peninsula is analysed in order to extract the basic biogeographical patterns of the plant diversity contained in this group. A total of 999 taxa at the level of species and subspecies have been identified as the Iberian cold-adapted plants living in the mountains, representing 15% of the total Iberian flora. Their distribution patterns across the six main mountain ranges, including all the ranges with significant areas above 1600 m, have been analysed. Species richness is correlated with the area above that altitude. Four main floristic elements have been distinguished within the orophile flora: the Arctic-Boreal, the European Orophile, the Endemic and the Iberian-North African. The first two elements are mainly spread across the northern mountain ranges in a pattern symmetrical to the distribution of the Iberian-North African element. The Endemic element is the largest one and is better represented in the ranges with the highest summits. After an analysis of the taxonomic diversity (TD) of all ranges, it is evident that, if phylogenetic diversity is taken into account, the southern ranges are less diverse than expected, in contrast to the northern ones, in spite of the fact that they host a larger number of endemics. This means that, even when an element contains many species, biodiversity values may be diminished in case those species are phylogenetically related. This particularly concerns the Endemic element, composed mainly of narrowly related geo-vicariants. Concerning the vegetation, the communities inhabiting rupicolous habitats such as crevices and screes, as well as the psychro-xerophilous grasslands, are the main contributors to this flora. The biogeographical distribution of the vegetation units follows a north-south pattern, with a preference for the siliceous mountains in the Boreal and Temperate units and for the calcareous mountains in the case of the Mediterranean units. A number of Iberian units has their optimum in the central siliceous ranges, such as the Nardus grasslands.