According to the recent estimation for Northern Europe, about 1.8-2.6 M ha of agricultural land is available for afforestation and intensive biomass production (Rytter et al. 2016). However, the long-term effects of different species C sequestration potential are unknown on former agricultural land. For the basis of current project, the growth data was obtained from tree species (hybrid aspen, poplar, birch, spruce, larch and willow) experiments on five former agricultural sites along a latitudinal gradient in Sweden (56° to 64°N). Site index curves were calculated to predict the potential production for each tree species and different long-term scenarios were tested to investigate each species climate benefit potential on former agricultural lands. More detailed information about the experiment: Rytter, L. and Lundmark, T. 2010 Trädslagsförsök med inriktning på biomassaproduktion [Tree species trial with emphasis on biomass production]. Skogforsk, Arbetsrapport no 724, Uppsala, 24 p.