The flow structures under the effects of heterogeneous canopies have been shown to be significantly different from those under the effects of homogeneous canopies. The purpose of this study is to investigate how the changes in density and density uniformity of the canopy affect the turbulent characteristics of the flow in a partially vegetated channel. A comparative experiment is conducted, including two cases of homogeneous canopy with different densities and one case of heterogeneous canopy consisting of alternating sparse and dense vegetation patches. While the lateral profiles of Reynolds stress, magnitudes of quadrant motions, and high-order moments of velocity fluctuations present a high similarity within the shear layer, variations in both the density and density uniformity of the canopy markedly affect the turbulence at the interface between the canopy and the main channel. The results show that canopy …