Model-based potential distribution and productivity mapping of rosemary (Rosmarinus officinalis L.) in the Eastern Mediterranean Region

This study was conducted to determine the potential distribution areas and productivity levels of rosemary (Rosmarinus officinalis L. syn Salvia rosmarinus Spenn.), one of the characteristic species of the Mediterranean flora, in the Eastern Mediterranean Region of Turkey. Due to increasing demand and uncontrolled harvesting, the natural populations of rosemary have come under significant threat. The main objective of this research is to contribute to the sustainable use of the species. Within the scope of the study, fieldwork was carried out in 91 sample plots across Mersin and Adana provinces, where key productivity indicators as dry leaf yield, essential oil content and yield, and 1.8-cineole content and yield were evaluated. Based on the environmental data obtained, MaxEnt and Random Forest (RF) modeling techniques were employed to generate potential distribution and productivity maps of the species. Through MaxEnt modeling, the primary climatic and topographic variables affecting rosemary's distribution were identified, while the RF model enabled a detailed analysis of the factors influencing productivity. The results revealed that bio1 (annual mean temperature), bio11 (mean temperature of coldest quarter), and bio13 (precipitation of wettest month) are among the most influential bioclimatic variables affecting both distribution and productivity. Additionally, topographic variables such as shading, radiation index, and distance from the sea were found to significantly influence productivity metrics. In conclusion, this thesis provides a comprehensive ecological insight into the species' habitat preferences, potential distribution, and productivity, offering a valuable foundation for sustainable management of rosemary under current and future climate scenarios.