Forest water use and water use efficiency at elevated CO2: a model-data intercomparison at two contrasting temperate forest FACE sites - De, Kauwe MG; Medlyn, BE; Zaehle, S; Walker, AP; Dietze, MC; Hickler, T; Jain, AK; Luo, Y; Parton, WJ; Prentice, IC; Smith, B; Thornton, PE; et al. (GLOBAL CHANGE BIOLOGY, 2013)