This is a large project that is funded by NSF and DOE.  Our goal is to measure how energy and CO2 exchange change as boreal forests in central Canada recover from fire.  Boreal stands in Manitoba burn every 50 to 150 years.  These fires kill the vegetation, while consuming only a fraction of biomass.  The forests regenerate after fire, with the canopy closing in about 30 years. The residue left by the fire gradually decays during this time, possibly causing the forest to become a large, transient source of CO2 for one or more decades following fire. We are studying the relationship between stand age and gas exchange by deploying 7 eddy covariance towers in a series of stands that range in time since last burn (2, 5, 11, 17, 37, 70, 150 yrs).