The Boreal Ecosystem Research and Monitoring Sites (BERMS) program is designed to study the seasonal and inter-annual dynamics of carbon and energy exchanges from selected southern boreal sites in Saskatchewan, Canada. This paper will examine the seasonal characteristics of these exchanges in 2000 and 2001 from a dry conifer site (mature jack pine), a wet conifer site (mature black spruce), and a deciduous site (mature aspen). In particular, we will explore the roles of phenology and the timing of snowmelt in the spring on the annual exchanges. The issues of energy balance closure and the importance of the minor energy terms will be examined.