[1] Mekelle Univ, Dept Econ, POB 451, Mekelle, Tigray, Ethiopia
[2] Aarhus Univ, Aarhus Inst Adv Studies, Hoegh Guldbergs Gade 6B, DK-8000 Aarhus, Denmark
[3] James Hutton Inst, Social Econ & Geog Sci, Aberdeen AB15 8QH, Scotland
[4] James Hutton Inst, Social Econ & Geog Sci, Dundee DD2 5DA, Scotland
[5] Alma Mater Studiorum Univ Bologna, Dept Agr & Food Sci, Viale G Fanin 50, I-40137 Bologna, Italy