1. BIOCONNET, Biodiversity and Conservation Network; Department of Life Sciences; University of Siena; 53100 Siena Italy
2. CNR-IRPI; 06123 Perugia Italy
3. DAFNE, Department of Agriculture; Forests, Nature and Energy; University of Tuscia; 01100 Viterbo Italy
4. Vegetation Ecology and Conservation Biology; Institute of Ecology; FB 2, University of Bremen; D-28359 Bremen Germany