Predicting current and future distributions of wild medicinal shrubs Ephedra alata Decne (Ephedraceae) under climate change in Tunisia

Ephedra alata is a common wild medicinal plant species in Tunisia. The ongoing utilization of E. alata for medicinal applications and uses is threatened by the changing climate, and this can lead to the potential decline of E. alata's geographic distribution range in Tunisia. In this study, we use species distribution modeling to estimate both the current and future potential distribution of E. alata , providing a basis for E. alata suitable habitats across Tunisia. Herein, the future climate model was based on two future representative concentration pathways representing optimistic scenarios (RCP 2.6) and pessimistic scenarios (RCP 8.5) in the years 2070. The mean temperature of the coldest quarter, the temperature seasonality, and the precipitation of the driest quarter, known as bioclimatic variables, contribute significantly to the E. alata distributions. Under an optimistic scenario, the distribution ranges of E. alata remained stable. On the contrary, under a pessimistic scenario in 2070, the distribution ranges of E. alata across governorates in Tunisia will decline, with ranges of 44.17–95.35%, or climate change will cause the disapearance of E. alata . In the future, E. alata will only be available in the western region, where it was previously common in the central and eastern regions.