1. National Institute for Agrarian and Veterinary Research I.P, Oeiras, Portugal
2. Centre for the Research and Technology of Agro-environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal
3. Department of Applied Economics, University of Santiago de Compostela, Santiago de Compostela, Spain
4. Forest Research Centre (CEF), School of Agriculture (ISA), University of Lisbon, Lisboa, Portugal