The possible dynamic response of northern forests to global warming

Increasing greenhouse-gas concentrations in the atmosphere are expected to produce maximum warming in high latitudes, displacing the potential boreal forest zone of the northern hemisphere. The authors analyse the implications of this shift for forest composition and biomass dynamics across the present-day boreonemoral zone in Scandinavia, using a forest succession model that includes a generalized disturbance regime and realistic climatic effects on species' regeneration and growth. Temperature increases in the range of 2-4 K in summer and 5-6 K in winter, typical of simulated CO₂ doubling effects, force the boreonemoral zone >1000 km northward from C Sweden where dominance passes from Picea to Fagus, Quercus and Pinus over 150-200 yr. Simulated increases of 175-250 mm in annual precipitation are required to counteract drought, which would otherwise reduce forest biomass and increase the representation of the more drought-tolerant species. -from Authors