The Ebro Basin

Abstract

The Ebro Basin is located in the northeastern quadrant of the Iberian Peninsula, in the southern foothills of the Pyrenees, and excavated by its homonymous river. It is one of the largest catchments areas in the Iberian Peninsula. Its climate is Mediterranean with both a continental and semi-arid tendency due to the rain shadow effect of the surrounding mountain ranges. The vegetation in dry areas is made up by several groups: (1) Forests and woodlands dominated by Quercus rotundifolia, Q. coccifera, Pinus halepensis, Juniperus phoenicea and J. thurifera, and represented in small patches due to deforestation; (2) Garrigue on limestone or on gypsum substrates; on the latter, a group of gypsophytes constitutes the core of the communities. (3) Grasslands, which can be divided into: non-steppic, dominated by Brachypodium phoenicoides and B. retusum; steppic, dominated by Lygeum spartum and Stipa species; heavily grazed, dominated by Poa bulbosa; and annual grasslands of plants with ephemeral life cycles. There are two edaphically exceptional ecosystems: salty depressions and riparian ecosystems. The first are populated by a set of communities of succulent Chenopodioideae, such as Microcnemum coralloides, Salicornia patula and, mostly Suaeda braun-blanquetii which plays the most relevant role, together with Limonium latebracteatum; and woodland communities with Tamarix canariensis and T. boveana; reed communities with Juncus maritimus, J. gerardii and J. subulatus.; and annual communities dominated by Aeluropus littoralis and Sphenopus divaricatus. The riparian ecosystems are formed by forests, with willows (Salix neotricha), poplars (Populus alba, P. nigra), ashes (Fraxinus angustifolia), alders (Alnus glutinosa) and elms (Ulmus minor). In this environment Scirpoides holoschoenus communities are frequent, as well as Cynodon dactylon grasslands. Some comments about land use, concerning deforestation and irrigation are made, highlighting the historically intense human pressure on this territory.