Studies to assess the impacts of increasing atmospheric CO2 concentrations on the earth's climate indicate that winter temperatures are likely to be higher, and summers warmer and drier, at high latitudes. Carbon cycling in the boreal forests, which cover a large area of the globe in the northern hemisphere at these latitudes and contain massive stores of carbon in the soil, may be affected by sustained increases in temperature and associated changes in soil moisture. The ecological functioning of the boreal forest biome may also be altered.
BOREAS Boreal Ecosystem Atmosphere Study was an international, interdisciplinary study, carried out in Canada, designed to improved our understanding of the interactions between the boreal forest biome and the atmosphere, in order to clarify their roles in global change. BOREAS examined the sensitivity of the boreal forest biome to changes in the physical climate by measuring all components of the carbon cycle and biogeochemistry in the forests, and studying the biophysical feedbacks between the forests and atmosphere. These may be caused by changes in albedo, surface roughness and controls on evapotranspiration. Studies on carbon dynamics included measurements of CO2, CH4 and CO fluxes, and measurements of cover type, biomass, leaf areas index and ecophysiological measurements such as leaf photosynthesis, stomatal conductance, the fraction of photosynthetically active radiation absorbed by canopies and leaf water potential. Models describing the processes governing the exchange of gases between the forests and the atmosphere were improved and tested at local scales, using eddy-correlation measurements at nine different locations. Large-scale validation techniques included the use of satellite instruments and airborne eddy correlation and meteorological observations.
This paper provides an outline of the project, presents some preliminary results in the area of land-atmosphere interactions and forest carbon balance and provides an indication of the range of information that will be available from the BOREAS study, within the next two to three years.
Key words: landatmosphere interaction, carbon balance.
Correspondence: J.J. Landsberg, CSIRO Centre for Environmental Mechanics, G.P.O. Box 821, Canberra ACT 2601, Australia.
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E-mail: joe@enmech.csiro.au