Flora y vegetación del macizo occidental de la Sierra de Gredos (Sistema Central, España)

Abstract

The study area includes the supramediterranean, oro- and cryorosubmediterranean territories of the western Sierra de Gredos, comprising an altitudinal interval within 900 and 2423 m. It is located on the boundaries among the provinces of Ávila, Cáceres and Salamanca. The subhumid, humid and perhumid part of this territory is included into the Bejarano-Tormantino subsector (Bejarano-Gredense sector), comprising the mountains of the study area. The supramediterranean dry and flat area is included into the El Barco de Ávila biogeographical district, which is proposed as a new district, belonging to the Salmantino Sector. The Bejarano-Gredense and Salmantino sectors belong to the Carpetano-Leonesa province, Western Mediterranean Iberian province.

            The climatic vegetation of the El Barco de Ávila district (fundamentally dry and lower supramediterranean) is characterized by Junipero oxycedri-Quercetum rotundifoliae genistetosum tournefortii evergreen woodlands (36.1), Genisto floridae-Cytisetum scoparii broom shrublands (32.1) in their typical variants, Arrhenathero-Stipetum giganteae euphorbietosum oxyphyllae (27.3) and Centaureo-Stipetum lagascae euphorbietosum oxyphyllae (27.4) tussock grasslands, Santolino-Cistetum laurifolii euphorbietosum oxyphyllae (31.1) shrublands, Thymo-Plantaginetum radicatae euphorbietosum oxyphyllae shrublands (24.4) with Leucanthemopsis pulverulenta, Artemisio-Santolinetum rosmarinifoliae subnitrofilous shrublands (16.1), Festuco-Poetum bulbosae dry perennial grasslands, and Hispidello-Tuberarietum guttatae dry annual grasslands (25.2). Vegetation of rock crevices and rocky ledges corresponds to Asplenio-Cheilanthetum tinaei (10.1) and Digitali-Dianthetum lusitani (12.1), respectively. Hygrophilous vegetation consists of Fraxino angustifoliae-Quercetum pyrenaicae ash-oak deciduous forests (34.1), Rubo-Salicetum atrocinereae willow deciduous forests (34.3), Galio broteriani-Alnetum glutinosae alder deciduous forests (34.2) and Salicetum salviifoliae willow deciduous shrublands (34.4), Festuco-Agrostietum castellanae (27.1) and Agrostio-Arrhenatheretum bulbosi (28.4) meadows, Trifolio-Holoschoenetum (28.6) and Mentho suaveolentis-Juncetum inflexi rush-pastures (28.10).

            When precipitation increases, within the pluviometric interval between 550 and 650 mm precipitation it is the boundary from the Salmantino Sector (El Barco de Ávila district) into the Bejarano-Gredense sector (Bejarano and Tormantino districts). The supramediterranan climatic vegetation in the later districts is characterized by Festuco elegantis-Quercetum pyrenaicae oak deciduous forests (37.1), Genisto floridae-Cytisetum scoparii festucetosum elegantis broom shrublands (32.1) growing in the lower and medium supramediterranean belts, and Genisto cinerascentis-Cytisetum oromediterranei broom shrublands growing in the upper supramediterranean belt, Leucanthemopsio pallidae-Festucetum elegantis tussock grasslands (27.2), Thymo zygidis-Plantaginetum radicatae euphorbietosum oxyphyllae shrublands (24.4) growing in the medium supramediterranean belt, Arenario querioidis-Festucetum gredensis (24.3) in the upper supramediterranean and oro-submediterranean, Santolina oblongifolia and S. oblongifolia x rosmarinifolia subnitrofilous shrublands (16.2), Hispidello hispanicae-Tuberarietum guttatae annual grasslands (25.2) in the lower supramediterranean, and Triseto ovati-Agrostietum truncatulae annual grasslands (25.4) in the medium and higher supramediterranean, and also in the orosubmediterranean.