The role of olive groves in the conservation of Mediterranean orchids

Olive and olive oil production is one of the main agricultural activities in the Mediterranean region. Besides their economic importance, traditional and organic olive groves were also hy-pothesized to contribute to biodiversity conservation. For instance, the presence of terrestrial orchids in olive groves has long been known. It is, however, not well understood what ecological or biological traits of olive groves influence the species richness and abundance of these protected flora elements in these secondary habitats. We surveyed 273 olive groves across the mainland of three countries (France, Greece, Italy) and three islands under their administration (Corsica, Lesbos, Sardinia). The surveyed olive groves provided habitat to more than 60,000 orchid in-dividuals belonging to 45 species. Our results indicate that olive groves located on islands had a significantly greater potential for orchid conservation, as they harbored more species and in-dividuals than olive groves on the mainland. Furthermore, orchid presence and species richness was highest in olive groves located on islands with high diversity of pasture weeds or native woody species, while these results also highlight the more traditional use of island groves and a difference in the intensity of maintenance between island and mainland groves. Overall, our study suggests that Mediterranean olive groves contribute significantly to the conservation of diverse terrestrial orchid communities and highlights the importance of traditional management practices in olive groves that allow local biodiversity to flourish.