What is the plant biodiversity in a cultural landscape? A comparative, multi-scale and interdisciplinary study in olive groves and vineyards (Mediterranean France)

[Display omitted] •Olive and vine cultural landscapes are scattered along the urbanization gradient.•Richness increases in peri-urban landscape with weak disturbance, heritage concern.•Specialization pattern increases with distance to city, natural landscape and slope.•Spatial diversity is higher between vineyards and edges, and between home terroir.•Geographical and cultural factors improve the existing models of agro-biodiversity. In a context of agricultural intensification and increasing urbanization, the biodiversity of farmed landscapes is a key to improve the sustainability of agro-ecosystems. We seek to ascertain the plant biodiversity of farmed and abandoned vineyards and olive-groves and to identify the factors underlying it: natural and cultural; on local, landscape, and regional scales. To do so, we recorded and calculated the floral biodiversity of 106 georeferenced plots and 121 plot edges distributed across 6 French Mediterranean terroirs, surveyed the practices and perception of 55 farmers, and mapped the landscapes of 20 communes in a GIS. Statistical tests proved that richness and spatial diversity on plots are favored by local low intensity management integrating heritage and landscape objectives. The presence of edges augments the richness and diversity around vineyards. The highest value of spatial diversity was found using the terroir variable. Maximum richness is found in olive groves which are maintained by amateur gardeners and located in the middle of the urbanization gradient. The diversity of biological traits is listed according to: (a) an herbaceous diversity gradient explained by management; (b) a specialization gradient explained by landscapes and distance to large urban areas. Our results draw perspectives to improve existing models of the links between agriculture, biodiversity, and landscape, considering cultural and geographical factors. They lead to recommendations regarding the management of landscapes based on local knowledge and good practices.