The Balearic Islands

Abstract

The Balearic archipelago is located in the western Mediterranean Sea, just off the east coast of the Iberian Peninsula. The archipelago comprises four principal islands and some minor islands and islets, 10 of which are larger than 25 ha. These islands have a Mediterranean climate, mainly thermo-Mediterranean, although we can find meso- and supra-Mediterranean climates in the mountains of Majorca. Ombroclimates are present from humid to semi-arid, although sub-humid and dry are the most common. The lack of connections with the European continent since the Pliocene-Pleistocene periods and the inter-island isolation has resulted in the separation of two biotic sub-archipelagos: the Gymnesics (Majorca, Minorca and Cabrera) and the Pityusics (Ibiza and Formentera). The predominant forest vegetation consists of the evergreen forests, woodlands and sclerophyllous shrublands dominated by Quercus ilex, Pinus halepensis, Olea europaea, Pistacia lentiscus and Juniperus turbinata. In Majorca, broadleaved forests of Acer granatense and shrublands of Balearic boxwood (Buxus balearica) are also present. In the Gymnesics, some riverside forests exist (principally of Fraxinus angustifolia), and in the coastal areas, Tamarix forests are common. Scrub and grasslands constitute the most important substitution vegetation. Among the former, endemic Gymnesic cushion-like formations (xeroacanthic thickets) are common as well as the thermophilous garrigue (especially remarkable in the Pityusics). Grasslands are more diverse; the most important ones are dry perennial grasslands (of Brachypodium retusum and of Allium chamaemoly), pseudo-steppic grasslands of Ampelodesmos mauritanica (related to wildfires) and Hyparrhenia, annual grasslands on carbonate-containing substrata, annual grasslands on non-calcareous soils with Xolantha guttata (in parts of the North of Minorca), annual grasslands on skeletal soils rich in succulents, and annual grasslands on sandy soils and dunes. Endemic grasslands related to trampled soils of old cattle paths are unique and very scarce. The length and diversity of the archipelago’s coast and the importance of sea wind, especially in Minorca and some parts of Majorca, determine the importance of salt-marsh vegetation, dunes and coastal cliffs, which are also very unique. The existence of pronounced relief, especially steep in Majorca, favors the diffusion of different types of rupicolous vegetation in which numerous endemic species can be found. On the other hand, long, intense human pressure (agriculture, touristic and urban) has emphasized the importance of synanthropic vegetation.