Abstract: Vegetation structure’s role in secondary wind dispersal remains poorly understood. We used wind-tunnel experiments with standardized, artificially constructed vegetation treatments to quantify the proportion of diaspores dispersed beyond 5 m over bare ground and through 12 vegetation treatments that varied in cover (0–30%), life-form composition, vertical arrangement and horizontal pattern. Dispersal capacity declined consistently with increasing vegetation cover. At 10% cover, diaspores dispersed farther through shrub than herbaceous vegetation, whereas under some higher-cover and higher-wind conditions the pattern reversed. One-layer vegetation generally allowed greater dispersal than two-layer vegetation, especially under lower cover or higher wind speed. The effect of horizontal arrangement was weaker: aggregated vegetation increased dispersal relative to uniform vegetation only under low cover and high wind, and this difference disappeared at higher cover. Size-related diaspore traits were positively associated with secondary wind dispersal, whereas the trait axis dominated by mass and wing loading showed a negative association whose strength varied with vegetation cover. Thus, secondary wind dispersal is jointly shaped by vegetation structure and diaspore traits. These findings suggest that patch-scale vegetation structure may modify the physical filtering environment experienced by wind-dispersed diaspores. Future wind-dispersal models should incorporate vegetation interception and allow key trait effects to vary with vegetation structure.

Key words: diaspore traits, dispersal, life-form, vegetation cover, vegetation structure, wind tunnel, wing loading