Within the genus Olea, the olive (Olea europaea L.) possesses the largest geographic distribution, and several subspecies have been described. South-west Morocco harbours an endemic olive, O. europaea ssp. maroccana (Greuter & Burdet) P. Vargas et al., located in the western part of the High Atlas (mainly on the southern slope of the Ida-ou-Tanane massif) and in the western Anti Atlas. The existence and the taxonomic position of this tree have long remained uncertain, but the combination of several morphological traits is unique. Nuclear and cytoplasmic DNA polymorphism also demonstrate that this tree is a well-differentiated and relictual taxon, probably originating from an ancestral unit within tropical Africa. Our findings refute the opinions of several authors who consider ssp. maroccana to be intermediate between the cultivated olive (O. europaea ssp. europaea) and the Saharan olive (O. europaea ssp. laperrinei (Batt. & Trab.) Cif.). According to cpDNA and mtDNA analysis, the Moroccan olive and the Canarian olive (O. europaea ssp. guanchica P. Vargas et al.) are related and belong to the same sub-taxon. This biogeographical affinity is strongly supported by other recent phylogenetic studies. The long-term viability of ssp. maroccana is threatened by several factors: (1) limited distribution and reduced numbers of individuals within isolated populations, (2) fragmentation processes related to human and livestock pressures, and (3) putative gene flow between this taxon and the cultivated olive. In order to ensure the long-term survival of this endemic olive, a specific program of conservation should be implemented in the near future.

Conservation BiologyVolume 13, Issue 6 p. 1510-1513 Biodiversity Hotspots in the Mediterranean Basin: Setting Global Conservation Priorities Frédéric Médail, Frédéric Médail University of Aix-Marseille, F.S.T. St-Jérôme, Institut Méditerranéen d'Ecologie et de Paléoécologie (C.N.R.S.), Case 461, F-13397 Marseille cedex 20, France email f.medail@botmed.u-3mrs_frSearch for more papers by this authorPierre Quézel, Pierre Quézel University of Aix-Marseille, F.S.T. St-Jérôme, Institut Méditerranéen d'Ecologie et de Paléoécologie (C.N.R.S.), Case 461, F-13397 Marseille cedex 20, FranceSearch for more papers by this author Frédéric Médail, Frédéric Médail University of Aix-Marseille, F.S.T. St-Jérôme, Institut Méditerranéen d'Ecologie et de Paléoécologie (C.N.R.S.), Case 461, F-13397 Marseille cedex 20, France email f.medail@botmed.u-3mrs_frSearch for more papers by this authorPierre Quézel, Pierre Quézel University of Aix-Marseille, F.S.T. St-Jérôme, Institut Méditerranéen d'Ecologie et de Paléoécologie (C.N.R.S.), Case 461, F-13397 Marseille cedex 20, FranceSearch for more papers by this author First published: 24 December 2001 https://doi.org/10.1046/j.1523-1739.1999.98467.xCitations: 598 Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume13, Issue6December 1999Pages 1510-1513 RelatedInformation

The recent discovery of several dwarf palm (Chamaerops humilis L.) populations on the provencal coast raises the problem of the extension of this southern-west Mediterranean thermophilous species. Even though the hypothesis of extension by ornithochory from cultivated specimens could explain the presence of certain specimens, it would seem that this dynamic evolution is more probably related to an improvement in climatic conditions since the end of the last century combined with a decline in anthropozoogenic pressure. An increase of one-half to one degree centigrade in the average annual temperature has in fact been detected since at least 1950 at 4 meteorological stations near the dwarf palm populations studied. This phenomenon underline the extension of the thermo-mediterranean level whose existence has been often debated in the littoral of Provence.

The Acacia desert savanna nowadays occupies large areas south of the Anti-Atlas and in the lower valley of the Draa river. The present vegetation structures are complex and constituted by elements from either tropical, either mediterranean or saharian origin, which coexist and prevail according to the present ecological and climatic conditions. At the northern border, Acacia raddiana mingles with the still mediterranean structures dominated by Argania and Euphorbia echinus whereas, in the eastern part, above 500 m, the same Acacia constitutes, with Ziziphus lotus, an essentially saharan grouping which spreads eastwards to the Saoura river valley. In the Draa depression, various sahelo-saharan trees and shrubs give to the Acacia formations the nearly similar aspect they have in the central and southern Sahara. According to the edapho-geomorphologic criteria, various associations can be defined: Balanito aegyptiacae-Acacietum ehrenbergianae in the large sand-silty areas, Foleyolo billotii-Acacietum raddianae in the silt-sandy wadis, Rottboellio hirsutae-Maeruetum crassifoliae on the rocky sanded bars and Stipagrostido pungentis-Acacietum raddianae in the large sandy wadis.

Quercus ilex sensu lato plays an important role in Western Mediterranean ecosystems, but is poorly developed in the Eastern Mediterranean where it is often replaced by Quercus calliprinos.

Les auteurs etudient la structure syntaxonomique ainsi que le valeur ecologique et dynamique, des matorrals du Maroc Oriental, entre la frontiere algerienne a l'Est, et les chaines du Rif et du Moyen Atlas. Ils appartiennent a la classe des Ononido-Rosmarinetea en milieu le plus souvent semi-aride et s'inscrivent dans diverses series constituees par Tetraclinis articulata, Pinus halepensis, Juniperus turbinata et Quercus rotundifolia (...)

We propose a terminology to distinguish from others those plant species whose natural distributions were changed by human activities (voluntary or not). Such plants may be native or non-native. We also develop a typology of the different ways by which they become integrated or not into the indigenous flora.Plants associated with man usually increase their distribution. Impressive and rapid invasions of non-native plants often occur in the circum-Mediterranean region, mainly where artificial or artificialized ecosystems prevail. Contrarily, their impact is limited where well-balanced natural ecosystems are dominant. Only when the natural balance is disturbed (e.g. by fires, overgrazing, abandonment of traditional cultivation methods, reafforestation) is the distribution of the native flora severely modified. Invading species with sexual reproduction alone must be separated from those showing asexual reproduction abilities, whether natural or linked to human activities. The importance of seed adaptation for dispersal is emphasized. These plants associated with man in the Circum-Mediterranean region originate mainly from temperate North America and Tropical Africa, but in the Western Mediterranean region the impact of Eastern Mediterranean and Irano-Touranian element is also important. The contribution of plants from the other Mediterranean climatic zones is generally very weak, with some remarkable exceptions.KeywordsMediterranean RegionNative FloraCape PeninsulaWestern Mediterranean RegionIndigenous FloraThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

The development of socio-economic activity over the past ten years in the Mediterranean region has induced severe changes in the main natural forest ecosystems.

Evidence is presented for dynamic successions in the Provence on the basis of a multivariate analysis, of a very large sample. Different phases in the Quercus suber series on silicious substrate are shown. Also the evolution of the vegetation groupings on Ventoux and Sainte-Baume mountains on calcareous substrate and at different levels in the zonation is specified.