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In ecophysiology, bioclimatology and global change studies water stress has been generally quantified, during the growing season, in particular in Mediterranean climate. However, early research conducted in the Alps has shown the importance of rainfall continentality and, thus, of winter rainfall for plant species distribution. In this study, we first present in introduction the importance of rainfall continentality for vegetation distribution in Mediterranean climate, through the example of Northern Morocco. We, then, present the results of a bioclimatic study conducted on the eleven states of western USA, in which we used Canonical Correspondence Analysis to analyse the correlations existing between 500 vegetation plots and four climatic variables, the average minimum temperature of the coldest month, the length of the growing season, the rainfall continentality quantified using the Gams (1932) winter index and the summer water deficit. The main results showed the overwhelming importance of rainfall continentality and cold stress, before the length of the growing season and the summer water deficit. This study highlights the importance to distinguish in Mediterranean climate, rainfall continentality from summer water deficit, if we want to improve our predictions of changes in plant species distribution with climate change., Le stress hydrique est traditionnellement quantifié, notamment en région méditerranéenne, pendant la saison de la végétation, aussi bien en écophysiologie qu’en bioclimatologie ou dans les études sur le changement climatique. Néanmoins, des études réalisées dans les Alpes ont très tôt mis en évidence l’importance de la continentalité hydrique et donc des précipitations hivernales dans la répartition des espèces végétales. Dans cette étude nous rappelons en introduction l’importance de la continentalité hydrique pour la distribution des végétaux en climat méditerranéen, à travers l’exemple du Maroc septentrional. Nous présentons ensuite les résultats d’une étude bioclimatique réalisée sur les onze états de l’ouest des États-Unis où nous avons corrélé par analyse canonique des correspondances 500 relevés de végétation de type biogéographique à quatre variables climatiques majeures, la moyenne des températures minimales du mois le plus froid, la longueur de la saison de végétation, la continentalité hydrique mesurée par l’angle de Gams (1932) hivernal et l’aridité estivale. Les résultats de cette étude mettent en évidence une importance primordiale de la continentalité hydrique corrélée également aux températures minimales, suivie de la longueur de la saison de végétation et de l’aridité estivale. Cette étude met donc en évidence la nécessité de distinguer, en particulier dans le contexte de la bioclimatologie méditerranéenne, la continentalité hydrique de l’aridité estivale, notamment si l’on veut améliorer notre pouvoir prédictif de l’effet du changement climatique sur la distribution des espèces végétales., Michalet Richard. L’importance de la continentalité hydrique dans les montagnes méditerranéennes : l’exemple du Maroc et de la Californie / The importance of rainfall continentality in the Mediterranean mountains: the example of Morocco and California. In: Ecologia mediterranea, tome 44 n°2, 2018. Hommage scientifique au professeur Pierre Quézel (1926-2015) pp. 31-44.

This article analyzes partial data published in the “Flora Corsica” in order to characterize the Corsican vascular flora. These analyses focus on different aspects of the flora such as species richness, taxonomic distribution, abundance and life-forms at different vegetation belts, habitats and substrates. The results are compared with other geographic regions, particularly from the European Mediterranean and adjacent areas. The decrease of species richness with an increase of altitude as well as the sharp decrease of Fabaceae has been confirmed. Regarding the biological spectrum, the decrease of the therophytes with an increase of altitude is obvious and compensated by the increase of the hemicryptophytes. On Corsica several peculiarities have been highlighted in the different ecological compartments: 1. the littoral and the cryo-oromediterranean belts appear to be very different from the others in many features; 2. the rocky habitats are shown to be especially important for the diversity of families such as Poaceae and Caryophyllaceae; 3. calcareous areas are shown to be extremely important for the alpha diversity as well as for the restricted range taxa. Finally, the specificity of the flora growing on the ultramafic outcrops is confirmed and emphazised.

JEANMONOD, D., Y. NACIRI, A. SCHLUSSEL & J. GAMISANS (20 15). Floristic analyses of the Corsican flora : biogeographical origin and endemism. Candollea 70 : 21-41. In English. English and French abstracts. DOI : http://dx.doi.org/10.15553/c2015v701a3 This article discusses various aspects of the biogeographical origin and endemism of the Corsican flora based on data retrieved from “Flora Corsica” project. It focuses on species richness, taxonomy, life forms, taxa abundance, distribution in vegetation belts, habitats and substrate types. The results are compared to other geographic regions, particularly Mediterranean ones. These data show that in Corsica the species of Mediterranean origin are slightly more numerous than those of Holarctic origin. It is surprising that the Holarctic elements start to dominate at low altitude in the supramediterranean belt. The endemic flora (12.7 %) shows distribution patterns often distinct from those of the non-endemic native flora, particularly regarding taxonomy, biological types and altitudinal distributions. The rates of hemicryptophytes and chamaephytes are for instance higher for the former compared to the latter while it is the reverse for therophytes. These rates are quite similar to those recorded in Sardinia, but rather different from those of other Mediterranean islands. More unexpected is the abundance pattern of endemic species which is quite similar to that of non-endemic ones. However, strictly endemic Corsican species are generally rarer than subendemics. The number of endemic species increases from the coast to the montane belt and then decreases in the upper belts. The percentage of endemic species, meanwhile, regularly increases from the thermomediterranean belt to the alpine one where it reachs a maximum of 43.1 %. The endemic flora also shows a wider altitudinal spectrum than other native species. The distribution of endemic species in the different Corsican habitats is slightly different from the one recorded for the indigeneous taxa. Endemics are however preferentially found in rocky habitats, but without any preference for a particular substrate. In the endemic flora, the Mediterranean origin is predominant but this trend is more marked in subendemics. The strict Corsican endemics have a mostly Holarctic origin and are more often found at high altitudes. These results shed light on the specificity of the Corsican endemic flora and should help the management of endemic species. Resume

This article presents the floristic, structural, and syntaxonomical features of plant assemblages in temporary wetlands and the pattern of the corresponding habitat types; according to the Habitats Directive. Nine pristine temporary wetlands covering a wide range of shapes, elevations and substrates were monitored. The "within temporary wetlands" hydrological gradient was strong enough to drive the vegetation and habitat type patterns. Plant assemblages presented a spatial arrangement in three concentric belts repeatedly present in each site in the same relative position. The presence of the H3120 habitat type was recognized in the central and in the intermediate belt. The outer belt was the more suitable for the presence of the H3170* priority habitat. Therefore, it should represent the main conservation target within temporary wetlands. On the other hand, it was the smallest in size (only 13% of the total surface) and in some cases absent, inconspicuous, or severely fragmented.