1. NERC Centre for Ecology and Hydrology, Edinburgh; Bush Estate Penicuik Midlothian EH26 0QB UK
2. Institute of Evolutionary Biology; School of Biological Sciences; Ashworth Laboratories; University of Edinburgh; Edinburgh EH9 3JT UK
3. Forest Research, Northern Research Station; Roslin Midlothian EH25 9SY UK
4. Institute of Biosciences and BioResources; Division of Florence; National Research Council; Via Madonna del Piano, 10 50019 Sesto Fiorentino (Firenze) Italy
5. Institute of Dendrology; Polish Academy of Sciences; Parkowa 5 62-035 Kórnik Poland