1. D. A. Wardle, O. Zackrisson, G. Hörnberg, Department of Forest Vegetation Ecology, Faculty of Forestry, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
2. C. Gallet, Laboratoire Dynamique des Ecosystemes d'Altitude, Centre Interdisciplinaire des Science de la Montagne Université de Savoie, F-73376 Le Bourget-du-Lac Cedex, France.