This chapter characterizes the aerodynamic mass and energy fluxes over forest canopies. These canopies are rough surfaces wherein flow-gradient assumptions may not be valid, leading to exponentialExponential zone in airflow profile wind profiles in trunk spaces and understory, superimposed by logarithmic profiles above the top of canopies. This leads to airflow regimes wherein canopy stomatal resistance depends on tree physiological factors and short- and long-term phenomena interacting with aerodynamic variables. Forest canopies are also very prone to intermittent events, such as gusts or ejectionsEjection, and wake formation in trees downstream, adding components to the usual kinetic energy equations and influencing turbulence spectral dynamics and particle transport. Analyzing drag processes in canopies, wind tunnelsWind tunnel experimentation, and fields also allows us to characterize phenomena such as tree bending and pulling. Compared with lower canopies, the evapotranspiration regime of these canopies is also coupled with the moisture of soil and atmosphere, with transient flow mechanisms particularly relevant in trunk and understory spaces. Finally, forest canopies are relevant in carbon balance dynamics, primarily related to the net ecosystem exchange, on a micro or global scale, and these dynamics reflect the influence of physical and biological factors in carbon sinking.