Carbon dioxide is one of the major greenhouse gases being cycled by forests. Mature boreal forests are often carbon sinks, however, following disturbance, forests can become carbon sources. Three forest sites in central Saskatchewan burned in 1977 (F77 site), 1989 (F89 site), and 1998 (F98 site) were studied using eddy covariance to obtain measurements of the energy, carbon, and water budgets. Latent heat flux density increased gradually over time at F98 but remained lower than F77 and F89. Weekly net ecosystem production was lower at F98 than at F77 and F89. F77 lost 40 g C m-2 and 79 g C m-2 in 2004 and 2005, respectively. F89 gained 177 g C m-2, 113 g C m-2, and 88 g C m-2 in 2003, 2004, and 2005, respectively. F98 lost 5 g C m-2, 17 g C m-2, and 52 g C m-2 during these three years, respectively.