Contribution des lianes à la biodiversité forestière méditerranéenne

Abstract

The objectives of the study were to evaluate the levels of taxonomic richness of vines in Mediterranean forests on the basis of a meta-analysis gathering data from the phytosociological literature. 229 forest communities were gathered in five main types : deciduous oak forests (G) ; evergreen oak forests (J), deciduous mountain forests (F), conifer forests (K), floodplain forests (U). Four life-traits were associated to the analysis (foliar type, mode of climbing, longevity and place in the forest strata). The total number of vines is 51, dominated by Fabaceae and Convolvulaceae. Hedera helix is the most abundant liana followed by Smilax aspersa, Asparagus acutifolius and Tamus communis. The global mean richness in vines is 6.9 species, which corresponds to a proportion of 12.4% related to the mean total richness of the forests. The most species rich forests in vines are the alluvial forests (U), the deciduous forests (G) and the evergreen forests (J). Vines of Mediterranean forests are mainly deciduous, perennial and live in understoreys. Vines present however different life-traits according to forest types, which were gathered in two groups : 1) the floodplain forest, highly favourable to woody vines ; 2) the other forest communities, characterized by a lower forest dynamics and thus a more stable architecture. Vines are small and perennial (hemicryptophytes, nanophanerophytes). Evergreen oaks are particularly rich in sclerophyllous vines. Deciduous oak forests are favourable to vine diversity because of deep soils and low altitudes, but vines are restricted to understoreys, except shade tolerant phanerophytes such as Hedera helix.