1. WSL Swiss Federal Institute for Forest, Snow and Landscape Research, CH‐8903 Birmensdorf, Switzerland
2. ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Via Anguillarese 301, I‐00123 Rome, Italy
3. Department of Arboriculture, Botany and Plant Pathology, University of Naples Federico II, via Università 100, I‐80055 Portici (Naples), Italy
4. Max Plank Institute for Biogeochemistry, Box 100164, D‐07701, Jena, Germany
5. Paul Scherrer Institute, CH‐5232 Villigen, Switzerland