The contribution of organized motions to buoyancy heat flux was determined for several time scales by applying wavelet decomposition to signals of vertical velocity and air temperature. Measurements were performed using an eddy covariance system installed over the Pantanal wetland, in Brazil, during two campaigns (1998 and 1999). The signals were decomposed in several time scales and then used in the quadrant analysis. Overall, coherent structures were responsible for ∼40% of the buoyancy heat flux, if the contributions of ejections and sweeps are summed over the range of 10–100 s, which excludes the contribution of stochastic high‐frequency turbulence and low‐frequency mesoscale motions. Copyright © 2011 Royal Meteorological Society