Évolution de la végétation du marais de Lavours (Ain, France) à quarante-cinq ans d'intervalle (1967-2012)

Abstract

Evolution of the Lavours marsh vegetation with a forty-five years interval (1967-2012). - Vegetation maps of the Lavours marsh realized 45 years apart are compared. The main changes in vegetal landscape and land use include : (i) transformation into crop fields of large surfaces of wet meadows, (ii) the spontaneous or chosen development of forest and (iii) the development of an open eutrophic vegetation, due to the water table lowering and the subsequent nutrient enrichment of habitats on silt substrate. In this context, the Réserve naturelle nationale du Marais de Lavours plays a major role for open habitats conservation on peat soils, which have almost disappeared in the rest of the marsh. The situation of open habitats on silt substrate is more moderate because half of them are outside of the nature reserve, dispached in small unmanaged islands.