1. CREAF; E08193 Bellaterra (Cerdanyola del Vallès); Catalonia Spain
2. Universitat Autònoma de Barcelona; E08193 Bellaterra (Cerdanyola del Vallès); Catalonia Spain
3. CEFE UMR 5175; CNRS; Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; Montpellier Cedex 5 France
4. Department of Environmental Systems Science; Forest Ecology; Institute of Terrestrial Ecosystems; ETH Zürich; Zürich Switzerland