Effects of vegetation structure and seed morphology on secondary wind dispersal strategies

Abstract

Vegetation structure is an important factor influencing the secondary dispersal distance of wind-dispersed seeds. How vegetation structure and seed characteristics interact to affect seed secondary dispersal strategies remains unclear. We collected data on seed morphological and aerodynamic traits, lift-off wind and dispersal velocities for 12 wind-dispersed species with six types of appendages using a large-scale wind tunnel simulating the seed secondary wind dispersal across six simulated vegetation structures of desert steppe, typical steppe and meadow steppe to analyze the effects of vegetation structures and seed traits on the seed secondary dispersal strategy. Seeds with pappi exhibiting large projected area, low mass, low wing loading and low terminal velocity were less affected by vegetation obstruction and tended to adopt telechory strategies across all vegetation structures. Conversely, seeds with one wing that demonstrated a small projected area, high mass, wing loading and terminal velocity were less affected by vegetation structures and tended to adopt an antitelechory strategy. Seeds with disc-shaped, four wings, balloons and thorns, characterized by higher mass, wing loading, density and terminal velocity, adopted a shift from telechory, atelechory or antitelechory strategies depending on vegetation structures. In sparse vegetation structures (bare ground or simulated desert steppe), they mostly adopt telechory or atelechory strategies, whereas in dense and high vegetation structures (simulated typical steppe and meadow steppe), they adopt antitelechory or atelechory strategies. In conclusion, secondary seed wind-dispersal strategies are jointly determined by the interaction between vegetation structure and seed morphology characteristics.