1. The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
2. Université de Technologie de Compiègne, CNRS-FRE 3580, Centre de Recherche de Royallieu, 60203 COMPIEGNE CEDEX, France
3. Birmingham Institute of Forest Research and School of Biosciences University of Birmingham, Birmingham B15 2TT, UK
4. School of Biological Sciences, The University of Reading, Reading, UK
5. SRUC, Department of Rural Land Use, Aberdeen, AB21 9YA, UK