Biogeographical Synthesis of Andalusia (Southern Spain)
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Journal of Biogeography (1997) 24, 915±928 Biogeographical synthesis of Andalusia (southern Spain) Salvador Rivas-MartÂõnez*,Alfredo Asensi², Blanca DõÂez-Garretas², JoaquÂõn Molero³ and Francisco Valle³ *Departamento de BiologõÂa Vegetal, Facultad de Farmacia, Universidad Complutense, E-28040 Madrid, ²Departamento de BiologõÂa Vegetal, Facultad de Ciencias, Universidad de MaÂlaga, Apdo. 59, E-29080 MaÂlaga, Spain and ³Departamento de BiologõÂa Vegetal, Universidad de Granada, E-18001 Granada, Spain Abstract. Andalusia is a large territory of almost and analysis of the endemic taxa, series and plant 90,000 km2 in the south of Spain. The marked heterogeneity communities found in the territory. of its orographic, lithological and climatic features aVords its plants and vegetation a high degree of biodiversity. A biogeographical classi®cation for Andalusia is proposed, Key words. Biogeography, plant communities, endemic based on studies of the physical environment, bioclimatic taxa, bioclimatic data, south Spain. Resumen. La regioÂnmaÂs meridional de EspanÄa el estudio del medio fõÂsico se propone una tipologõÂa (AndalucõÂa) es un territorio heteroÂgeneo y fuertemente biogeogra®ca para esta regioÂn. contrastado donde se combinan diversos factores (geoloÂgicos, climaÂticos, eda®cos, etc.) que determinan una acusada variabilidad en su ¯ora y vegetacioÂn. Este trabajo Palabras clave. BiogeografõÂa, comunidades vegetales, analiza la ¯ora endeÂmica del territorio y sus comunidades bioclimatologõÂa, taxa endeÂmicos, ®tosociologõÂa, Sur de vegetales. Con estos datos y la informacioÂn aportada por EspanÄa. Meusel, Jaeger & Weinert, 1965). The synthesis of Braun- INTRODUCTION Blanquet not only de®nes territories, but also includes four Traditionally the plant biotic component has been used hierarchical biogeographical levels (district, sector, province for the de®nition and recognition of biogeographical and region). These de®nitions remain in use today, with units. For some systematic botanists, plant chorology (or some modi®cations (GeÂhu & Rivas-MartõÂnez, 1980; Rivas- phytogeography) stresses the phylogeny and distribution of MartõÂnez, 1982). high-level taxaÐgenera and familiesÐat the expense of The elemental unit of biogeographical typology is the the areas of distribution and geovicariance of species and tesella. It can be de®ned as a territory of variable area, subspecies (Axelrod & Raven, 1972; Takhtajan, 1986), taxa which is either continuous or discontinuous according which indicate current climatic conditions, are in equilibrium to the surrounding geomorphology, and is ecologically with these conditions and compete with each other. This homogeneous (i.e. the characteristics of its climate and soil procedure has created a discipline that Takhtajan (1986) lead to a single potential vegetation type and a single refers to as `chorionomy' (phytochorionomy): placing more sequence of vegetation types or replacing communities). emphasis on the climatic and ¯oristic conditions of the past The `district' is characterized not only by certain taxa and than on the current conditions in order to determine the associations which are absent in neighbouring districts, but distribution of species and plant communities (Rivas- also by the traditional use of the territory by man according MartõÂnez et al., 1993). to the fertility of the soil and climatic and edaphic However, it is evident that the study of vegetation from homogeneity. The `sector' is a large area with distinct a ¯oristic point of view (i.e. the `Sigma' school of geographical identity, characterized by exclusive taxa and phytosociology) is a fundamental tool for the delimitation syntaxa and particular altitudinal and edaphic catenas. of territories (Takhtajan, 1986; Rivas-MartõÂnez, 1987), since Particular series and permanent communities or subseries it enables us to adjust for certain situations of discontinuity are found. The chorological `province' is of wide extension. which occur in the biogeographical units. It has an original ¯ora and endemic subelement, while In Europe, the most widely accepted biogeographical containing its own geoseries and macroseries. An original syntheses are those based on the distribution of taxa zonation of vegetation is a further characteristic of and communities, together with certain physiognomical the province. The `region' is a vast territory, sometimes and ecological factors (Braun-Blanquet, 1951; BoloÂs, 1963; transinsular or transcontinental, with endemic ¯ora and 1997 Blackwell Science Ltd 915 916 Salvador Rivas-MartõÂnez et al. vegetation, original vegetation belts and also particular mainly composed of metamorphic rocks (mica-schists, macrobioclimates or bioclimates. The `kingdom' is the quartzite, amphibolite, etc.); the AlpujaÂrride, also formed highest rank in biogeography, grouping a set of regions of such materials as Paleozoic mica-schists and quartzite, with similar history, ¯ora, vegetation and climate. but with overlying limestone and Triassic dolomite; and, According to a recent biogeographical review by Rivas- ®nally, the MalaÂguide, which is more complex, composed MartõÂnez (1990), the Iberian Peninsula, which falls within of not only phyllite, Palaeozoic mica-schists and Triassic the Holarctic kingdom, is divided into two regions: the rocks, but also of a series of post-Triassic materials, Euro±Siberian and the Mediterranean. This division is especially in the MaÂlaga area (Bourgeois, 1978). mainly based on phytocoenological (particular vegetation The mountains run parallel to the coast, with two chains, series) and bioclimatic (Mediterranean index) criteria, one littoral and the other pre-littoral. Longitudinal corridors as well as characteristic ¯ora and vegetation. In the connect the two, widening out as we move eastwards, and Euro±Siberian region the peninsular territories are there are extensive Miocene sedimentation areas. In such distributed into two superprovinces, the Alpine±Pyrennean an orographically complex territory considerable altitudes and the Atlantic, while in the Mediterranean region two are reached, such as MulhaceÂn (3478 mÐthe highest peak other superprovinces are represented: the Ibero±Levantine in the Iberian Peninsula); Veleta (3392 m); Alcazaba and the Ibero±Atlantic, with eastern Andalusia (SE Spain) (3366 m); La Sagra (2381 m); GaÂdor (2236 m); Baza forming part of the former, and western Andalusia (SW (2269 m); Filabres (2168 m); MaÂgina (2167 m); Tejeda Spain) the latter. (2065 m); Harana (1931 m); Ronda (1919 m); Cazorla Since the publication of the ®rst chorological syntheses (1830 m); Almijara (1824 m); Segura (1809 m); Estancias proposed for the Iberian Peninsula, Balearic and Canary (1718 m); Loja (1671 m); Grazalema (1654 m); and Pandera Islands (Rivas-MartõÂnez, 1973; Rivas-MartõÂnez et al., 1977), (1601 m). several authors have de®ned and delimited the boundaries The Campo de Gibraltar mountains are another of the of various peninsular and insular territories (e.g. Rivas- most characteristic formations of the Andalusian landscape. MartõÂnez et al., 1990; Alcaraz, SaÂnchez GoÂmez&Dela They belong to the so-called `AljõÂbico unit' and are Torre, 1991; Rivas-MartõÂnez et al., 1991; Rivas-MartõÂnez et composed of Miocene sandstone which overlies Eocene al., 1993). The objective of this study is to propose a clays. hierarchical classi®cation for Andalusia down to district The post-orogenic sedimentary basins are interior level. In order to delineate the biogeographical units of the depressions of the Baetic Cordilleras: physiographical units territory we have used geographical, bioclimatic, geological with well-de®ned characteristics diVerentiating them from and geomorphological criteria, as well as the distribution the surrounding mountains. They are depressed areas of mainly endemic taxa and communities. (Penibaetic Depression or Intra-Baetic Trench), aligned along the Sub-Baetic±Baetic boundary. The largest basins forming this depression are those of Ronda, Antequera, Granada, Hoya de MaÂlaga, Guadix±Baza and Campo de STUDY AREA NõÂjar. Finally, on the coast of AlmerõÂa there is a massifÐthe The surface area of Andalusia is 87,268 km2, i.e. Cabo de Gata rangeÐof volcanic origin. It is a Neogene approximately one-®fth of the Spanish part of the Iberian complex with various stages of magma emission, from the Peninsula. The territory is characterized by three Lower Miocene to the Messinian, where later erosion has morphostructural units: Sierra Morena, the northern constructed one of the most striking landscapes in boundary; the Baetic Cordillera, to the south; and, between Andalusia. these two mountain ranges, the Guadalquivir Depression, an Such orographical diversity plays a key role in favouring extensive tectonic fosse ®lled with Tertiary and Quaternary the biodiversity of the ¯ora and vegetation, altering the local sediments (Fig. 1). climates and their in¯uence on other physical environmental Sierra Morena is the southern boundary of the Spanish parameters. The land relief creates an altitudinal bioclimatic high plain (`meseta'). It consists of a mountain range sequence which is particularly important in Andalusia, since stretching from NE to SW, and is composed of metamorphic the altitude of the Baetic CordillerasÐespecially in the rocks (sandstone, schists, shale, batholith, etc.). The Baetic Sierra NevadaÐhas enabled nearly all the bioclimatic levels Cordillera is an extensive geological unit stretching from to develop, as described below. It is also responsible for the