Chapter 11 The Iberian Ranges and Highlands Manuel Peinado, Juan Luis Aguirre, and Alejandro Aparicio Abstract One of Spain’s main mountain ranges, the Iberian System, separates the Ebro basin and Meseta Central (Inner Plateau) and runs northwest-southeast from the La Bureba corridor in Burgos to the Mediterranean coastal ranges in Castello´n and Valencia. The barren, rugged slopes of this range cover an area close to 61,140 km 2 . Each mountain chain has different geological characteristics depending on the outcropping materials of the Alpine orogeny, either those of the Hercynian basement or Mesozoic materials. The former give rise to the acid soils of the Sierras of Demanda or Moncayo and Peaks of Urbio´ n, and the latter to the basic substrates of the Sierras of Gu´dar, Javalambre, the Iberian High Plateau (“parameras” or “pa´ramos”) and the serranı ´as of Cuenca and Albarracı ´n. Vegetation varies according to both geological/edaphic factors and a complex orogeny. The prevailing ombroclimate is subhumid, reaching humid to hyperhumid, and the predominant thermoclimate is supramediterranean. Potential vegetation mainly comprises forests. Rocky areas, steep slopes or southern expo- sures of lower mountain zones sustain large patches of supramediterranean Quercus rotundifolia forests. Marcescent oak forests, both of Quercus pyrenaica and Quercus faginea subsp. faginea (Q. faginea hereafter), dominate large areas of the gentle relief of the sierras’ foothills though, in many zones, they have been repopulated with pines or given over to grazing. In more moist areas, generally of northern or eastern exposures, we find beech forests dominated by Fagus silvatica. In the north-west zone of the Iberian System, these occupy extensive areas. Large expanses of conifers from plantations of the twentieth century exist, though in some zones we find natural pine forests dominated by Pinus sylvestris var. iberica, P. nigra subsp. salzmannii and P. nigra subsp. latisquama (P. iberica, P. salzmannii and P. latisquama, respectively, hereafter). Also appearing are some relict groves dominated by P. uncinata. The dominance of coniferous formations is magnified by the large expanses of Juniperus thurifera woodlands of the Iberian parameras and of creeping Juniperus sabina in some summit areas. The online version of this chapter (doi:10.1007/978-3-319-54784-8_11) contains supplementary material, which is available to authorized users. M. Peinado (*) • J.L. Aguirre • A. Aparicio Department of Life Sciences (Plant Biology), University of Alcala´, 28871-Alcala´ de Henares, Madrid, Spain e-mail: manuel.lorca@uah.es © 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_11 439