Analysis of the Population Structure and Dynamic of Endemic Salvia ceratophylloides Ard. (Lamiaceae)

Understanding how changes of any origin interact with the structure and survival of entire populations is very important for the protection and conservation of threatened, rare and/or endemic species. In this study, structure and population dynamics of Salvia ceratophylloides Ard., a precious endemic species, belonging to the subgenus Sclarea (Moench) Benth., section Plethiosphace Benth. (Lamiaceae) exclusive to the suburban environments of Reggio Calabria (Southern Italy), was analysed. Interactions between this species and its different growth habitats were examined. Moreover, the disturbance factors which directly affect the demographic viability of the species, influencing its growth, reproduction and distribution in its distribution area were identified. From 2019 to 2021, a census by counting individuals of all the known stations, recorded according to a specific protocol, was carried out. The recorded data were statistically analysed and compared with those of the phytosociological surveys carried out using the Braun-Blanquet method and summarised in phytosociological classes, in accordance with the hierarchical floristic classification system of vascular plant communities, accepted at national and European levels. The structure of the different populations was also related to the different threat factors that afflict S. ceratophylloides. It was observed that the most structured populations of S. ceratophylloides were found in natural and semi-natural environments where the anthropogenic disturbance was minor, while populations with an irregular structure were found in sites exposed to disturbances of various origins. The different phytosociological classes do not interact directly on population structure. The most important factors affecting structure and distribution are disturbances of various origins, in particular anthropogenic and phytosanitary disturbances. In order to keep populations balanced and stable over time, it would be useful to adopt conservation measures for the species and the habitat in which they live, with practical solutions for the following: (a) to limit infestations by insects that parasitize stems and seeds; (b) to prevent mowing, fires, grazing and the introduction of invasive alien species.