Résumé. Dans le Haut Atlas, les pelouses humides et pozzines constituent des pâturages assez convoités. Leur flore se caractérise par une grande richesse spécifique: 165 taxons inventoriés dans la zone d’étude (plateau de l’Oukaimeden, plateau de Tichka et l’amont de la haute vallée d’Ait Mizane) avec un taux d’endémisme estimé à 30,3% et un degré de rareté qui atteint 31%. Dans un contexte dominé par l’élément méditerranéen, la flore de ces pelouses est très enrichie de souches septentrionales 15,7%, repoussées vers nos latitudes méridionales lors des dernières glaciations. Ces zones humides vulnérables de par leur structure, fonctionnement écologique et état de conservation, se trouvent très touchées par les changements climatiques et les mutations environnementales récentes. Summary. In the High Atlas mountains, the wet grasslands and pozzines constitute a highly coveted pastoral resource. Its flora is characterized by a great specific richness: 165 taxa are recorded in the study area (Oukaimeden plateau, Tichka plateau and the upstream of the Ait Mizane high valley) and schow a rate of endemism estimated at 30.3% and a degree of rarity reaching 31%. In a Mediterranean context, the wet grasslands flora is supplemented with plants of northern origin 15.7%, pushed towards the extreme southern latitudes during the last glaciations. These wet pastures, highly sensitive by their structure, ecological functions and their conservation state, are very affected by the climatic changes and the global environmental changes.

Wetlands are a very important universal heritage; in the Moroccan High Atlas mountains the geomorphology and the slopes evolution determine the existence of the numerous projecting ledges of pozzines on plateaus and oozing. This is particularly the case in Oukaimeden site located at 75 km south of Marrakesh. These wet grasslands have been developed on small surface areas supported by soils water accumulation; and close to the sources and on some banks constitute wetlands of high floristic richness, which makes them very coveted pastures by local populations. These wet pastures are highly sensitive to climatic factors. Recent climatic changes, the anthropic and pastoral pressures and the global environmental changes, affect these zones at the level of their structure (areas, soil characteristics...) and their ecological functions. In the Oukaimeden plateau, the use of aerial photography made it possible to carry out a detailed follow up of the hydraulic adjustments (dam construction in the 1970s) as well as the setting up of new adjustments (tracks, paths, drain channel) on the structure and functioning of these grasslands