Energy, water, and carbon budgets of young post-fire boreal forests in central Saskatchewan

Models and previous studies have shown that climate change will bring increased global temperatures. The major cause of climate change is the emission of greenhouse gases into the atmosphere from anthropogenic and natural sources. 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, releasing carbon into the atmosphere. As temperatures increase with climate change, it is predicted that the frequency of forest fires in the boreal forest will increase. Fire will impact the energy and water budgets of the boreal forests which will also impact the carbon budget. Three previously burned forest sites in central Saskatchewan were studied for a minimum of three years using eddy covariance to obtain measurements of the energy, carbon, and water budget. Sites were burned in 1977 (F77 site), 1989 (F89 site), and 1998 (F98 site). Net radiation was similar at all sites for the duration of the study with maximum summer net radiation levels near 13 MJ m-2 d-1. Sensible heat flux density and soil heat flux density were similar at F77 and F89 by 2005. Difference in vegetation characteristics were best illustrated by latent heat flux. Latent heat flux density increased gradually over time at F98. Latent heat flux densities were similar at F77 and F89 throughout the study period. Soil heat flux density was similar at all sites in 2004 and 2005 with maximum soil heat flux values of approximately 1 MJ m-2 d-1. Weekly net ecosystem production values at F89 were similar to the F77 site in 2004 and 2005 while F98 remained lower than the mature sites. 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. Understanding the recovery of boreal forests following fire furthers understanding of how climate change and disturbance in boreal forests could impact local, regional, and global climates in the future.