The Iberian Ranges and Highlands

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 Castellón and Valencia. The barren, rugged slopes of this range cover an area close to 61,140 km². 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 Urbión, and the latter to the basic substrates of the Sierras of Gúdar, Javalambre, the Iberian High Plateau (“parameras” or “páramos”) and the serranías of Cuenca and Albarracín.

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 exposures 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.

Scrublands range from heaths dominated by Cytisus and Erica species in the rainiest zones, to scrub of the laurel-leaf rock rose Cistus laurifolius (“jarales”) and Genista scorpius (“ahulagares”) in drier or more exposed areas. In some shady zones appear formations of Buxus sempervirens or Berberis hispanica and in windier zones spiny formations of Genista rigidissima or Erinacea anthyllis. In the northern region occur mixed Ilex aquifolium woodland formations comprising several deciduous trees (Acer monspeliensis, A. campestre, Corylus avellana, etc.).

Riverbank formations include those typical of the interior peninsula with a dominance of series of forest, woodlands and thickets dominated by willows (Salix purpurea, S. alba, S. atrocinerea, etc.), poplars (Populus alba, P. nigra) and elms (Ulmus minor). The sierras comprise large rocky habitats that sustain the growth of an interesting rupicolous flora with several significant endemisms. Habitats of basic substrate on rocky, steep slopes are dominated by open thickets of Juniperus phoenicea (“sabina negral”).

The Iberian System is one of the most under-populated regions of Spain with large expanses of Teruel, Soria, Burgos, Cuenca and Guadalajara being home to fewer than 10 inhabitants/km². Its setting is therefore one of immense, well-preserved zones. The area comprises mountains and sierras that are largely protected, sometimes because they form part of the Red Natura 2000 or because they harbour a protected feature such as the Natural Parks of the Alto Tajo, Moncayo, Sierra de Cebollera, Laguna Negra and Circos Glaciares de Urbión.

1 Supplementary Electronic Material (S)

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