[1] Finnish Meteorological Institute, P.O. Box 503, Helsinki,FI-00101, Finland
[2] Finnish Environment Institute, Latokartanonkaari 11, Helsinki,FI-00790, Finland
[3] Climate Research Division, Environment and Climate Change Canada, ON,M3H 5T4, Canada
[4] Max-Planck-Institute for Biogeochemistry, PF 100164, Jena,D-07701, Germany
[5] Dalhousie University, Halifax,NS,B3H 4R2, Canada
[6] Université de Montréal, Quebec,H2V 2B8, Canada
[7] University of Helsinki, P.O. Box 68, FI-00014 University of Helsinki, Finland
[8] Estonian University of Life Sciences, Kreutzwaldi 1, Tartu,EE-51006, Estonia
[9] Swedish University of Agricultural Sciences, Umeå,SE-90183, Sweden
[10] Natural Resources Institute Finland, Helsinki,FI-00790, Finland
[11] Lund University, Lund,SE-22362, Sweden
[12] University of Eastern Finland, P.O. Box 1627, Kuopio,FI-70211, Finland