1. Joint Research Unit CTFC – AGROTECNIO – CERCA , Av. Alcalde Rovira Roure 191, Lleida E-25198 , Spain
2. Departament of Crop and Forest Sciences, University of Lleida , Av. Alcalde Rovira Roure 191, Lleida E-25198 , Spain
3. Woodwell Climate Research Center , 149 Woods Hole Road, Falmouth, MA 02540 , USA