A large share, estimated at 12-25%, of the annual anthropogenic greenhouse gas emissions is attributed to global deforestation. Increasing the forested areas therefore has a positive impact on carbon (C) sequestration and mitigation of high atmospheric CO2 concentrations. Fast-growing species, such as willow and poplar, are of high interest as producers of biomass for fuel, but also as C sinks. The present study estimated the rate of C sequestration in biomass and soil in willow and poplar plantations. Calculations were based on above- and below-ground biomass production data from field experiments, including fine root turnover, litter decomposition rates, and production levels from commercial plantations. Accumulation of C in woody biomass, above and below ground, was estimated at 76.6-80.1 Mg C ha(-1) and accumulation of C in the soil at 9.0-10.3 Mg C ha(-1) over the first 20-22 years. The average rates of C sequestration were 3.5-4.0 Mg C ha(-1) yr(-1) in woody biomass, and 0.4-0.5 Mg C ha(-1) yr(-1) in the soil. If 400,000 ha of abandoned arable land in Sweden were planted with willow and poplar, about 1.5 Tg C would be sequestered annually in woody biomass and 0.2 Tg C in soils. This would be nearly one tenth of the annual anthropogenic emissions of C in Sweden today. These calculations show the potential of fast-growing plantations on arable land to mitigate the effect of high CO2 concentrations over a short time span. Knowledge gaps were found during the calculation process and future research areas were suggested. (C) 2011 Elsevier Ltd. All rights reserved.