Floristic diversity and vegetation dynamics in an arid Mediterranean wetland: the case of Sehb El Masjoune Basin, Central Morocco

The Sehb El Masjoune basin, located in the Oum Er-Rbia watershed (Morocco), is classified as both a Site of Biological and Ecological Interest (SBEI) and a Key Biodiversity Area (KBA). This study presents a phytoecological assessment based on 18 vegetation surveys conducted before and during the site's flooding (November 2020 – June 2021). A total of 70 vascular plant species, representing 29 families, were recorded. Annual therophytes dominate the flora (68%), indicating arid environmental conditions and strong anthropogenic pressures, particularly overgrazing. The chorological analysis of the recorded taxa showed that most of the recorded species belonged to mediterranean (72.8%). The presence of seven endemic and two threatened species highlights the site’s ecological value. The analysis of the principal component analysis (PCA) revealed the differentiation of five major plant associations, each reflecting distinct ecological conditions related to substrate type and salinity. The results demonstrate the ecological significance of the basin and emphasize the urgent need for a dedicated conservation and management plan. This study provides a baseline for future biodiversity monitoring and sustainable management efforts in this nationally and internationally important site.