1. Department of Agricultural Sciences and Desertification Research Centre, University of Sassari, Sassari, Italy
2. School of Agriculture, Policy and Development, Department of Applied Economics and Marketing, University of Reading, Reading, UK
3. Department of Chemical and Geological Sciences, University of Cagliari, Cittadella Universitaria, Cagliari, Italy
4. Desertification Research Centre, University of Sassari, Sassari, Italy