[1] Univ Southampton, Sch Biol Sci, Southampton SO16 7PX, Hants, England
[2] Brookhaven Natl Lab, Dept Environm Sci, Upton, NY 11973 USA
[3] Univ Illinois, Dept Crop Sci, Urbana, IL 61801 USA
[4] Peking Univ, Coll Life Sci, Beijing 100871, Peoples R China
[5] CNR, Inst Biometeorol, I-50145 Florence, Italy
[6] Michigan Technol Univ, Sch Forest Resources & Environm Sci, Houghton, MI 49931 USA
[7] Univ Tuscia, Dept Forest Environm & Resources DISAFRI, I-01100 Viterbo, Italy