Modelling the Short-Term Effect of Climate Change on the Productivity of Selected Tree Species in Nordic Countries

The process-based simulation model, BIOMASS, which included boreal features, was used to quantify and compare the effect of increased temperature and elevated atmospheric carbon dioxide concentration on net primary production for Scots pine Pinus sylvestris, Norway spruce Picea abies, European beech Fagus sylvatica, and black cottonwood Populus trichocarpa growing in Scandinavia. The model is described. Three years of current climate were used from each site for the reference simulation, and two warming scenarios were then simulated involving increased mean annual air temperatures of 2 and 4 degree C, respectively. Scenarios with increased CO sub(2) alone and in combination with the two temperature scenarios were also used. Results indicated that the deciduous species were less responsive to elevated temperature than the coniferous species, but the increased temperatures increased the rates of respiration of the various tree components throughout the year for all sites and species. Elevated CO sub(2) alone increased net primary production for the coniferous species in Finland, Sweden, and Norway by 25 40%, while net primary production for beech was increased 58% in Denmark.