1. Environmental Science Department Second University of Naples 81100 Caserta Italy
2. Centre for Bio‐Archeology and Ecology Ecole Pratique des Hautes Etudes (PALECO EPHE) Institut de Botanique University of Montpellier 2 F–34090 Montpellier France
3. PSI Paul Scherrer Institute 5232 Villigen Switzerland
4. WSL Swiss Federal Institute for Forest Snow and Landscape Research 8903 Birmensdorf Switzerland
5. IBAF‐Institute of agro‐environmental and Forest Biology CNR Porano Italy
6. Department of Microbiology and Plant Biology University of Oklahoma Norman OK USA
7. Oak Ridge National Laboratory Environmental Sciences Division Oak Ridge TN USA
8. Department of Soil and Crop Sciences Colorado State University Fort Collins CO USA