Overview on serpentinophyte flora in the Mediterranean Basin biodiversity hotspot

Ophiolitic flora is particularly rich in tropical and Mediterranean biomes, representing more than 10% of the native flora where they occur. In the Mediterranean Basin, the largest hotspot of biodiversity between the Mediterranean biome, studies on ultramafic flora are geographically fragmented but despite this, they shows the importance of these extreme soil conditions on the species adaptation and evolution/speciation. Overall, to date, no attempts have been made to diversity and geographic variation of ultramafic and mafic outcrops in the biodiversity hotspot of Mediterranean Basin. With this study we want: (i) to create an instrument as digital map of the mafic and ultramafic units in the Mediterranean hotspot of biodiversity, (ii) implementing a comprehensive knowledge framework on mafic and ultramafic floristic diversity in the study area and (iii) analyzing factors that determine the geographical variation of ophiolite richness. From regional, national and international geoportals we created the first digital map of the mafic and ultramafic outcrops in the Mediterranean Basin: serpentine soils extension consists of 24,000 km2 (the 1.15% of the total Mediterranean Basin biodiversity hotspot). We characterized the outcrops in extention, fragmentation and shapes using using landscapemetrics R package, and we also extracted the bioclimatic variables and climate change velocity using CHELSA bioclim dataset. Data about the serpentinophyte flora in the study area were collected from 90 published works (i.e., papers, Masters or PhD theses). The 22% of the mafic and ultramafic outcrops are inside of Protected Areas, the biggest one inside is the Troodos outcrop, in Cyprus, that is also the second one biggest outcrop in the study area. In serpentine outcrops inside the Mediterranean Basin occur 521 taxa of biogeographical interests, rare or endemics. Of these, 267 taxa are serpentinophyte obligated. Twelve taxa are assessed as Critically Endangered (2% of the total taxa) by IUCN Red List Assessments, 36 taxa as Endangered (7%), 41 as Vulnerable (8%), 89 as Least Concerned (17%), 29 Not Threatened (6%) and 16 Data Deficient (3%). All the others (57% of the total taxa) are assessed as Not Evaluated. The factors used for this first work to determine the geographical richness of serpentine flora in the Mediterranean Basin seems to be the outcrop extension, the mean altitude and the proximity of the patches of the outcrops. While more analyses needs to be done to understand better the geographical variation of ophiolite richness, first analyses also show that serpentine flora should need an improvement on its conservation status and knowledge.