Large carbon-sink potential by Kyoto forests in Sweden—a case study on willow plantations

Fluxes of CO₂ were measured in a 75-ha short-rotation willow plantation at Enkôping, central Sweden. The plantation was irrigated with wastewater for fertilization and water-filtering purposes. The harvested biomass was used locally for combined heat and power production. The plantation was a sink of ca. 8 tonnes C ha^-1 during 2003, of which ca. 50% was estimated to be attributed to fertilization. Biomass increment by shoot growth was 5 tonnes C ha^-1 during the same year. Belowground carbon allocation was estimated to 3 tonnes C ha^-1 yr^-1 by a model that relates carbon allocation to shoot growth. Thus, the ecosystem carbon balance was closed by these estimations. The carbon uptake by the willow plantation was 5.5 times as high compared to a normally managed spruce forest, but only half as high as from an experimental, well-managed willow plantation in the same region. This illustrates the vast potential of short-rotation willow plantations for CO₂ uptake from the atmosphere.