Habitat characterization and decline of Critically Endangered Onobrychis conferta subsp. conferta

Abstract

Rare endemic plant species are very susceptible to anthropogenic threats and natural changes, thereby facing a high risk of extinction. The Mediterranean Basin supports a rich flora with high percentages of endemic species. An iconic case of Mediterranean narrow endemic plant taxon is represented by Onobrychis conferta subsp. conferta (Desf.) Desv. (Fabaceae). Management of this species requires better information on its habitat requirements and population status. Field surveys and historical records were used to characterize the distribution of O. conferta in Tunisia. Habitats were characterized using topography, soils, climate, and land cover variables. Expeditions on ten previously reported sites revealed the presence of O. conferta in only one of the previous recorded localities and, for the first time, in two new localities. We recorded a sharp decreasing trend for the total number of plants per population in all locations over 6-year period. Our findings showed that the current status of O. conferta in Tunisia is Critically Endangered (CR). Onobrychis conferta faces an extremely high risk of extinction in the wild. Therefore, prompt comprehensive conservation actions are needed to ensure its survival. We propose a conservation and recovery recommendations including in situ and ex situ conservation actions. In situ actions are aimed at minimizing the effects of the identified threats and to create new populations of O. conferta in its characterized habitat. Ex situ actions include an environmental education campaign and seed preservation.