Abstract: Plants reduce wind speed resulting in the lower soil wind erosion. The characteristics of wind velocity profile are a reflection of wind speed variation at the surface of different plants. In this paper, the wind velocity profiles above two plant surfaces (the first is the slender plants and the second is the plants with large upper part and small lower part) are measured at different plant density and free-stream wind speed in a wind tunnel, then the aerodynamic roughness length and zero-plane displacement are analyzed. The results show that the aerodynamic roughness length of the two plant surfaces increases with plant density according to the power function, and its ratio to plant height also increases with lateral cover by the power law. At the same plant density or lateral cover, the aerodynamic roughness length of the second plant surface is larger than that of the first one. The zero-plane displacement of the first plant surface increases first and then decreases with the increase of plant density, while the zero-plane displacement of the second plant surface is generally unaffected by plant density.

Key words: plant morphology, wind velocity profile, aerodynamic roughness length, zero-plane displacement, wind tunnel experiment