An important option in the Swedish context to reduce its net emissions of carbon dioxide (CO2) is the increased use of biomass for energy and material substitution. On fallow agricultural land additional production of biomass would be possible. We analyse biomass production systems based on Norway spruce, hybrid poplar and willow hybrids and the use of this biomass to replace fossil energy and energy intensive material systems. The highest biomass production potential is for willow in southern Sweden. Fertilisation management of spruce could shorten the rotation lengths by about 17%. The fertilised production of Norway spruce with use of harvested timber for construction and use of remaining woody biomass for heat and power production gives the largest reductions of carbon emissions per hectare under the assumptions made. The use of willow for heat and power and of fertilised spruce for a wood product mix lead to the highest fossil primary energy savings in our scenarios. Spruce cultivations can achieve considerable carbon emission reductions in the long term, but willow and poplar might be a good option when fossil energy savings and carbon emission reductions should be achieved in the short term.