Terrestrial C sequestration potential in Norway under present and future climate

Terrestrial ecosystems in the northern hemisphere have been a significant sink in the global C cycle. However, strength and duration of the terrestrial C sink is uncertain and will impact future trends in atmospheric CO2 concentrations. Likely factors, al so relevant in Norway, to affect the terrestrial C sink strength are i) increases in the tree line due to climate warming, and regrowth of forest to present tree line because past land use lowered the tree line artificially, ii) enhanced soil organic matt er decomposition and iii) forest management practices. Under the Kyoto protocol, there is a wish to differentiate accounting rules for C sequestration obtained by direct human practices and indirectly by climate change. The relative importance of these fa ctors was not evaluated in a single modelling framework, so far. Norway is suitable and important as a case study to evaluate consequences of climate and land use change on terrestrial C sequestration. Historical C sequestration will estimated based on f orest inventory data and land cover information and provide a basis for the scenario analysis. Potential tree line changes as a response to climate warming and the inherited low tree line due to past land use will be evaluated based on results from ongoin g NFR projects and additional field surveys in alpine vegetation areas and regional climate change scenarios. Forest standing stocks and soil organic matter stores under climate and land use change, including the use of biofuel, will be predicted and upsc aled to land cover categories available for the whole of Norway. National databases on forest, soils and climate will be used to explore relations between climate, vegetation cover and C storage to substantiate model predictions. The effect of predicted C sequestration on global warming will be calculated, and compared with changes in albedo (ground reflectance) resulting from land cover changes under the aforementioned scenarios.