1. Centro de Estudios Avanzados de Blanes (CEAB); Blanes Spain
2. Departamento Edafologia y Quimica Agricola; Facultad di Biologia; Santiago Spain
3. Institute of Geoecology Technische Universitä Braunschweig; Braunschweig Germany
4. Department of Ecology and Environmental Science; Umeå University; Umeå Sweden