Broad-ranged, highly disjunct, locally rare and severely endangered: the challenging risk assessment and a global conservation strategy for Erica sicula Guss. sensu lato (Ericaceae)
Authors: Pasta Salvatore , El Zein Hicham , Şentürk Ozan , Gücel Salih , de Simone Leopoldo , de Montmollin Bertrand 
Published: April 2024

The distribution of Erica sicula Guss. sensu lato ranges throughout the central-Eastern Mediterranean Basin. However, this species, which probably represents one of the most ancestral members of the genus Erica, shows a significantly disjointed and fragmented distribution pattern and is subject to multiple threats, leading to continuous regression at the local scale. The species is distributed across five regions, Sicily, Libya, Cyprus, Anatolia and Lebanon, and counts two subspecies, subsp. sicula and subsp. bocquetii, represented by 29 and 8 subpopulations, respectively. This work provides a global update on the knowledge related to the distribution, ecology and conservation status of its two subspecies. New distributional analyses and ecologically relevant data were collected from fieldwork, literature and herbarium specimens. In Sicily, unmanned aerial systems and high-resolution digital elevation models were employed to perform a detailed census of the only extant subpopulation. This enabled a comprehensive mapping of its distribution and the calculation of its 3D occupation surface. Based on the result of our analyses, species is Least Concern (LC) at the global level, despite each subspecies and subpopulation being classified as nationally endangered. Erica sicula subsp. sicula was assessed as Critically Endangered (CR) (B1ab(i,ii,iii,iv) + 2ab(i,ii,iii,iv)) in northwestern Sicily where two out of the three subpopulations have probably disappeared. The situation of E. sicula subsp. sicula in eastern Mediterranean is equally alarming, being assessed under the category VU B1ab(i,ii,iii,iv) + 2ab(i,ii,iii,iv) in the three countries where it occurs; in Lebanon, it is severely threatened by the increasing impact of quarrying, urban sprawl, road and dam construction, in the island of Cyprus it is prone to the growing impact of goat overgrazing and fire, whilst in Anatolia it is affected by urban sprawl and coastal touristic development. In Libya, E. sicula subsp. sicula was evaluated as VU (B1ab(iii) + 2ab(iii)) considering the current degradation of the quality of its habitat. E. sicula subsp. bocquetii, previously known to occur only in few locations on the mountains of southern Anatolia and recently found in several other locations at lower altitudes, was assessed as VU (B1ab(iii) + 2ab(iii)). Further fieldwork is recommended to better assess the demographic trend of the different subpopulations. Moreover, genetic analyses are needed to clarify the taxonomic value of several infraspecific taxa previously described and help targeting future in-situ and ex-situ conservation projects on the most unique and genetically rich subpopulations. Improving knowledge and the conservation strategies of taxa like Erica sicula s.l. requires the expertise of specialists from all the countries concerned, making it essential to maintain networks of experts in the Mediterranean.