The Pyrenees

The Pyrenees is a large mountain system stretching over the Iberian isthmus, and thus encompassing three distinct vegetation regions: medio-European, Mediterranean and Alpine. It includes contrasting landscapes in accordance with this large-scale pattern and also with smaller scales related to continentality, bedrock type, landform and ancient anthropic land use. The northern side and the western edge of the Pyrenees are formed of short valleys with steep slopes. Being strongly influenced by Atlantic winds, these areas experience rainy bioclimates across the elevation gradient. Therefore, the vegetation is set according to the altitudinal zonation model found in other medio-European mountains. This starts with a submontane belt supporting mixed deciduous forests, acidophilous oakwoods and heaths, which at 900–1000 m gives way to the montane belt, best characterized by beech forests, and by fir forests, heaths and meadows. The Iberian side of the Pyrenees extends southwards over secondary ranges— known as the pre-Pyrenees—and internal depressions, and shows a more complex zonation, since it changes from Mediterranean to montane and then to alpine landscapes. This transition is sharper in the central part of the Iberian side, where the submontane belt combines dominant units related to marcescent oakwoods with sclerophyllous oakwoods and xerophilous scrubland on steeper rocky landforms. From 1100 to 1300 m upwards, the montane belt still expresses some continental Mediterranean influence such as bearing widespread Scots pinewoods together with meso-xerophilous grassland and box scrub. Beech and fir forests and other mesophilous units are secluded on moister slopes. High mountain landscapes develop from 1600 to 1800 m up to the highest summits (peaking at 3404 m with Aneto), with less pronounced differences between the main north and south sides. The potential treeline ecotone, found at 2200–2450 m, makes the transition between the subalpine and the alpine belts; the former bearing forests of mountain pine and related vegetation units, the latter formed by contrasting vegetation mosaics where rock units become dominant towards the highest elevations. J.M. Ninot (*) • E. Carrillo • A. Ferré Institute for Research on Biodiversity (IRBio) & Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, E-08028 Barcelona, Spain e-mail: [email protected] © Springer International Publishing AG 2017 J. Loidi (ed.), The Vegetation of the Iberian Peninsula, Plant and Vegetation 12, DOI 10.1007/978-3-319-54784-8_8 323