The objective of this study is to compare process related to CO2 storage (ie photosynthesis and accumulation of soil C and CO2 release (ie. plant respiration and decomposition) for evergreen and deciduous forests in two contrasting boreal climates and is part of a large international study (BOREAS) to examine terrestrial atmosphere interactions in boreal ecosystems in Prince Albert National Park, Saskatchewan and nelson House, Manitoba, Canada. Data collected during the study will increase our understanding of the influence of major biotic and abiotic factors on carbon cycling in boreal forests. A concurrent activity will be to develop computer simulation models that we will use to examine the influence of different climate change scenarios on the growth of boreal forests. %%% The global carbon cycle recently has been the focus of much research in an attempt to explain the rising atmospheric CO2 concentration; CO2 is of interest because it is a major greenhouse gas. Forests can be a net sink (ie. store CO2), a source (ie. release CO2) or in equilibrium (ie. no net change) depending upon stand age, stand vigor and climate. Boreal forest comprise approximately 25% of the total forested area in the world and contain greater than 40% of the total world soil carbon; therefore, this forest biome is likely to have an important role in the global carbon cycle. Moreover, the role of boreal forests in the global carbon cycle may change more in the future than any other biome because general circulation models that are used to predict future climate suggests that the boreal biome will experience the greatest change in climate.