Rare plants on Mount Amiata, Italy: Vulnerability to extinction on an ecological ‘island’ Original Research Article

The vulnerability to local extinction of 21 uncommon plants occurring on Mount Amiata, an isolated mountain in peninsular Italy, is analysed in relation to 17 factors concerning anthropic threat, isolation and biological features of populations. Isolation increases with altitude and vulnerability is weakly but significantly correlated with both altitude and isolation. Cluster analysis identifies five groups with a different average vulnerability, each including species with similar threat profiles. Ordination indicates that demographic variables and anthropic disturbance are the most important in determining the vulnerability of the most threatened populations. Populations of wide-ranging species which have been ‘trapped’ within the ecological island as a consequence of historical variations in distribution and abundance pose, in general pose more serious conservation problems than taxa naturally sparse or narrow-ranged. Isolation or disjunction do not necessarily cause vulnerability; some populations are buffered against demographic stochasticity thanks to their biological and structural features.