[1] Univ Tuscia, Fac Agraria, I-01100 Viterbo, Italy
[2] Newcastle Univ, Dept Agr Econ & Food Mkt, Ctr Res Environm Appraisal & Management, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[3] Univ York, York YO1 5DD, N Yorkshire, England
[4] Queens Univ Belfast, Dept Agr & Food Econ, Belfast, Antrim, North Ireland
[5] Univ Wisconsin, Dept Forest Ecol & Management, Madison, WI USA