Is a restricted niche the explanation for species vulnerability? Insights from a large field survey of Astragalus tragacantha L. (Fabaceae)

Understanding the environmental drivers of ecological niche rare plant species is crucial for conservation programs. We have examined Astragalus tragacantha L. This main component relict west-Mediterranean phrygana, a community impacted by urbanization and landscape degradation which are major threats biodiversity Mediterranean littoral. During our field work in Provence (southern France), we studied habitat characteristics, floristic composition carried out an exhaustive population census. The census revealed less than five thousand individuals, strong fragmentation high ratio foliar necrosis. Niche analyses were conducted considering either all individuals or separated size stages. Analyses based on did not support hypothesis that too narrow itself explains vulnerability A. tragacantha. However, modelling differences among stages supporting restricted regeneration wider range past. Our comprehensive survey underlines worrying situation sets baseline conservation.