Lecture series in Ecology and Environmental Research SS 2017

Long term and large scale studies on plant biotas of the Tuscan Archipelago

Biogeographical patterns of archipelagic plant communities are still poorly understood because of the uneven amount of information at different geographical scales (i.e. within islands vs. between islands) and along time scale. However, the recent availability of large floristic and vegetation databases offers the opportunity for testing explicit hypotheses based on theoretical biogeographical and ecological assumptions. The Tuscan Archipelago in Italy represents a very fortunate case, with modern floristic exploration started in 1930 and continued virtually constantly and with collection of phytosociological data spanning more than 40 years.
In the present research, we use the floristic data relative to the occurrence of 1831 species in 16 islands and islets in the period 1830-1950 and 1950-2015 as well as 1334 phytosociological relevès with 790 species on the seven larger islands, to investigate the long term changes of island floras and archipelagic patterns of community composition. In particular we aimed to test if the long term floristic changes agreed to the prediction by the Equilibrium Theory of Island Biogeography (ETIB). Then, we used the phytosociological data base to test the role of the different habitat types versus the island identity in shaping the species composition of plant communities. Results showed major changes in floristic composition of islands and a clear scale dependence of such changes, suggesting that the observed deviation from ETIB expectations is an effect of land use changes. The vegetation analysis supported the idea that habitat type exerts a major role in shaping the local plant communities despite of the island identity and this is likely due to the limited isolation degree of most of the islands as well as the similarity of the habitat types.

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Invited by the Department of Biogeography as International Senior Research Fellow of the University of Bayreuth

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