School of Geography, Earth & Environmental Sciences (GEES) and Birmingham Institute of Forest Research, University of Birmingham Birmingham B15 2TT United Kingdom; and Centre for Ecology, Evolution & Environmental Changes/Azorean Biodiversity Group and Depto de Ciências e Engenharia do Ambiente, Universidade dos Açores Angra do Heroísmo, Açores PT-9700-042 Portugal; e-mail: [email protected]