Species distribution modelling to identify habitat islands for narrow endemics climate relicts: an update

Ptilostemon greuteri is one of the most intriguing narrow endemic plant species of the Mediterranean Basin and is considered among the most endangered and poorly studied woody vascular plants of this area. This broad-leaved woody thistle survives in two microrefugia in the North-Western coast of Sicily (Italy) and can be considered a climatic relict. It thrives in habitat islands consisting of NE-facing calcareous cliffs and ledges as well as at the bottom of narrow, steep and shaded gorges, which benefit from the sea humidity. To identify suitable habitat islands for conservation purposes, we performed a species distribution model using high resolution DEM and other DEM-derived microtopographic variables. The species distribution model identified very few sites suitable for the species; further field vegetation surveys validated the reliability of the model and unexpectedly enabled us to discover a second population of Hieracium lucidum, another narrow endemic species previously known only from Mount Gallo. Monitoring data from translocation activities using both survival and growth rate of newly introduced plantlets and seedballs showed that species distribution modelling can be an effective tool to identify suitable habitat islands for narrow endemics.