The conservation status of an endemic species of northern Sardinia: Centaurea horrida Badarò (Asteraceae)

Abstract

When assessing the conservation status of narrow endemic plants, life history traits must be taken into account, since endemics combine small population ranges and sizes, and long persistence with limited reproductive and dispersal ability. In this paper, we present the global assessment of the conservation status of a narrow endemic plant from the Sardinian‐Corsican biogeographic province, by applying IUCN criteria and categories, together with an evaluation of some reproductive traits. Centaurea horrida Badarò (Asteraceae) is an endemic species of northern Sardinia (Italy). It is protected by the Bern Convention (Appendix I) and listed as priority species by the “Habitat” Directive (92/43/EEC, Annex II). The species appears in the 1997 IUCN Red List as “Vulnerable” (VU). With the aim of evaluating the risk of extinction and of providing management tools for the network of protected areas in which this species is present, some reproductive traits have been evaluated, and the distribution, size and structure of its population have been measured according to IUCN 2006 Guidelines. Centaurea horrida is not able to self‐pollinate and its effective seed dispersal ability is limited. Its extent of occurrence is 172.43 km² and its area of occupancy is 108 km². Population size has been estimated at 11,719 adult individuals. Significant differences in adult densities among sites have been highlighted. The structure of the population is dominated by adult individuals (on average 68%), while the proportion of seedlings is only 7% on average. Its habitat underwent an extinction rate of 18% in 50 years. On the basis of the data gathered, the status to be assigned to C. horrida is that of “Endangered” (EN). This first attempt to evaluate the conservation status of a narrow endemic plant from the Sardinian‐Corsican biogeographic province allowed us to conclude that the management of rare species must be site‐specific and that there is urgent need to acquire detailed data on endangered species, especially within biodiversity hotspots, and to continuously update Annex II of the EU Habitat Directive and the IUCN Red List.

Keywords:

• IUCN
• Habitat Directive
• life history
• population size
• population structure
• reproductive traits

Acknowledgements

We would like to thank David Brett for improving the English version and Graziano Rossi for useful comments on the manuscript. This study was supported by funds from the Management Plans of ICS Asinara, Asinara National Park, and Protected Marine Area of Tavolara‐Punta Coda Cavallo to Rossella Filigheddu, and by the Management Plan of ICS Capo Caccia (with Foradada and Piana Islets) and Punta del Giglio to Emmanuele Farris. Funding by the Italian MIUR (RFO) to Rossella Filigheddu is acknowledged. This work constitutes part of the Ph.D. programme of Stefania Pisanu.