1. Department of Agriculture, University of Sassari, Viale Italia 39A, 07100 Sassari, Italy
2. HAFL, Bern University of Applied Sciences, Länggasse 85, CH-3052 Zollikofen, Switzerland
3. Institute of Geography (GIUB), University of Bern, CH-3012 Bern, Switzerland
4. Manaaki Whenua-Landcare Research, Lincoln 7608, New Zealand