Résumé
The Mediterranean basin is one of the 34 hotspots of terrestrial diversity and endemism. This region is facing an anthropogenic climate change, including a rise in mean temperature of between 2.2 and 5.1°C, a decline of 4-27% of annual rainfall during the XXIst century, with drastic changes in the pattern of rainfall distribution. According to this scenario, the region may be especially vulnerable, with probably more than 2,000 extinctions of plant species. Located in the Western part of the Mediterranean basin, the mountainous island of Corsica harbors a particularly rich flora, made of 2858 taxa of vascular plants, including 11% of endemics and 6% of Corsica-restricted taxa. Upon the expected climatic shift, Corsica island is a central area in terms of conservation of terrestrial plant diversity. In this context, a satisfactory evaluation of all realized attempts of plant conservation is crucial. This is the main goal of this first report presenting the assessment of sixteen years of in situ conservation operations that were carried out from 1984 to 2004 in Corsica. This paper gathers a set of 40 operations of plant population transfers in contexts of either restoration of rare and threatened habitat or safeguarding of populations of endangered plant taxa. All the transferred populations were protected (excepted Achillea maritima whose only picking in the intervention area is regulated) and part of the European Directive CE 92/43. All the operations except two came within the framework of the European Life program “Conservation des habitats naturels et des espèces végétales d’intérêt communautaire prioritaire de la Corse“ managed by the “Office de l’environnement de la Corse”. The two remaining operations, dealing respectively with Ophrys eleonorae and Achillea maritima conservation, were independently carried out by the French Forest Service (Office national des forêts) and the Conservatoire du littoral in Corsica. The data presented include 20 introductions, 18 population reinforcements and two in situ population transfers. Operations succeeded for 21 of them and failed for 16 of them. The three remaining operations could not be evaluated for various reasons. Among the 16 transferred taxa, four were phanerophytes (Juniperus oxycedrus subsp. macrocarpa, Genista aetnensis, Tamarix africana and Vitex agnus-castus), seven were hemicryptophytes (Anchusa crispa, Kosteletzkya pentacarpos, Lippia nodiflora, Naufraga balearica, Rouya polygama, Silene velutina and Woodwardia radicans) and three were chamephytes (Achillea maritima, Armeria pungens and Brassica insularis). The two remaining taxa were either geophyte (Ophrys eleonorae) or therophyte (Linaria flava subsp. sardoa). Interventions were carried out into coastal sandy (eight sites), riparian (three sites), flooded (two sites) and rocky (three sites) habitats. These operations provide new insights from methodological perspectives (intervention process, partner interactions, intervention modalities…) as well as enhance our knowledge of the biological models associated with moved populations (ecology and biology of rare Mediterranean species). The limits of these programs in terms of modalities of monitoring and data availability, as well as the way to improve the timing and the ability of partners to be involved in the process are exposed in order to optimize the success of future operations of habitat restoration. Le Bassin méditerranéen est à la fois identifié comme l’un des 34 points chauds mondiaux de diversité en espèces animales et végétales, mais aussi comme l’une des régions les plus menacées par les changements environnementaux. La Corse est au centre de ces enjeux de conservation du fait de sa grande diversité floristique, d’un fort endémisme et de la rareté d’un grand nombre de ses taxons. Dans ce contexte, les retours d’expérience sur les opérations de conservation réalisées in situ sont particulièrement précieux. C’est pour bénéficier de tels acquis que nous présentons ici le bilan d’un ensemble hétérogène d’opérations de conservation d’espèces végétales réalisées en Corse sur seize années (1987-2004). Ces opérations ont en commun d’avoir intégré le déplacement d’individus végétaux, soit à des fins de restauration d’habitat naturel, soit dans le but de transférer pour leur sauvegarde des populations de taxons rares menacés par des aménagements. Ce bilan résume 40 opérations dont il présente le détail des issues, soit 20 introductions, 18 renforcements de population et 2 opérations de transfert de population. Elles se sont soldées par 21 succès et 16 échecs, pour 3 opérations non évaluées. Les acquis méthodologiques (modalités d’intervention dans un cadre réglementaire, synergies entre partenaires) et biologiques (connaissance des modèles biologiques) générés par ces programmes sont présentés. Enfin, les limites en termes de jeux de données dispo-