Abstract: The structure of windbreak forest belts is the main factor affecting windbreak effect. The main purpose of this paper is to establish statistical models between windbreak effect of forest belts with different widths and spacing and the distance behind the windbreak forest belts so as to provide guidance for the construction of windbreak forests. The wind speeds at 0-10H (H is tree height) on the leeward side of forest belts with 4 kinds of widths and 5 kinds spacing are measured by wind tunnel test when the wind speed is 11 m·s^-1. The statistical model between windbreak effect and distance behind forest belts is constructed by using curve parameter estimation method, Fourier model and SSF model (Sum of Sin Functions) under different forest belt structures. The results shows that Fourier model had the best effect on fitting the relationship between the windbreak effect of different width forest belts and the distance behind the forest belts, and the coefficient of determination (R²) was above 98%. SSF model had the best effect on fitting the relationship between the windbreak effect of different spacing forest belts and the distance behind the forest belts, with the lowest coefficient of determination (R²) being 89%. According to the statistical model, when the wind speed is about 11 m·s^-1, the windbreak effect of the windbreak forest structure with a forest belt width of 8 m (two rows and one belt) has prominent advantage; among the five forest belts with different row spacing, the windbreak forest belt with a tree spacing of 8 m×8 m is the best structure for wind protection under the test conditions.

Key words: wind tunnel test, shelterbelt width, shelterbelt spacing, windbreak effect, statistical model