1. Irstea, UR EFNO, Domaine des Barres; FR-45290 Nogent-sur-Vernisson France
2. Dept of Physical Geography; Stockholm Univ.; SE-106 54 Stockholm Sweden
3. West-Vlaamse Intercommunale; BE-8310 Bruges Belgium
4. Dept of Biology; Terrestrial Ecology Unit, Ghent Univ.; BE-9000 Ghent Belgium
5. Faculty of Biology, Technische Univ. Darmstadt; DE-64287 Darmstadt Germany
6. Dept of Biology; Univ. of Bergen; Thormøhlensgate 53A NO-5006 Bergen Norway
7. Biodiversity Research/Systematic Botany, Univ. of Potsdam; Maulbeerallee 1 DE-14469 Potsdam Germany
8. Research Inst. for Nature and Forest; Kliniekstraat 25 BE-1070 Brussels Belgium
9. Faculty of Biology, Białowieża Geobotanical Station, Univ. of Warsaw; ul. Sportowa 19 PL-17-230 Białowieża Poland
10. Depto de Ecología; Univ. Autónoma de Madrid; ES-28049 Madrid Spain
11. Grontmij Netherlands B.V., De Molen 48 NL-3994 DB Houten the Netherlands
12. The James Hutton Inst.; Craigiebuckler, Aberdeen AB15 8QH UK
13. Inst. of Botany, Faculty of Biology and Preclinical Medicine, Univ. of Regensburg; DE-93040 Regensburg Germany
14. Ecological Site and Vegetation Studies, Univ. of Kassel; DE-34127 Kassel Germany