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 in southern Sweden with use of harvested timber for material or construction gives the largest reductions of carbon emissions per hectare in the long term. The use of willow and poplar for heat and power and of fertilised spruce for construction lead to the highest fossil primary energy savings in southern and central Sweden. Short-rotation willow and poplar are a good option when fossil energy savings and carbon emission reductions should be achieved in the short term.