Effects of plant crown characteristics on dispersal kernels of wind-dispersed seeds under low wind speeds

Abstract Plant crown can affect the seed dispersal process. Clarifying the influence of plant crown type on seed dispersal kernel is important for predicting species distribution. However, the effects of different plant crown types on seed dispersal have rarely been tested. To address this, we conducted wind tunnel experiments to investigate the average seed dispersal distance, range, kurtosis and skewness of 29 species with varying diaspore traits (e.g., appendage type, mass, projected area, shape index, wing loading and terminal velocity) under 3 wind speeds (2, 4 and 6 m s−1). We examined seeds passing through different crown types, classified based on crown size, branch density, and the presence or absence of leaves. We fitted functions to the seed dispersal distance and found that the Gaussian function provided the best fit. Our results showed that plant crown type had significant effects on dispersal kurtosis and skewness but not on the average dispersal distance or range under low wind speed conditions. Specifically, crown width and branch density influenced dispersal kurtosis, while the presence of leaves affected both kurtosis and skewness. Increasing wind speed reduced the influence of plant crowns on dispersal kurtosis and skewness. Although plant crowns did not significantly affect average seed dispersal distance, they altered the shape of the seed dispersal kernel. Consequently, while the dispersal range of seeds through different crowns remained relatively invariant, the density of dispersal varied significantly. These findings provide valuable insights into plant metapopulation dynamics and highlight the importance of considering crown architecture in seed dispersal studies.