Wind-driven seed dispersal differentially promotes seed trapping and retention across alpine plants

Seed dispersal can mediate species interactions between plants across life stages. Plants can physically stop seed movement (seed trapping) and prevent further dispersal following entrapment (seed retention). We therefore hypothesized seed trapping and retention rates depend on the physical attributes of interacting seeds and plants, including seed traits and plant length.

For combinations of co-occurring plant species in an alpine community, we experimentally measured seed trapping and retention potential. To measure seed trapping, we determined the rate at which seeds were unable to physically pass through vegetation without stopping after being launched at plants. To assess seed retention, we compared the rate that seeds left vegetation following entrapment across plant and seed species and by seed traits.

Seed trapping rates were higher for larger-sized plants and differed among plant species but not seed species. Seed trapping and retention rates were higher for plant species with denser vegetation. Seeds with a pappus were retained less than seeds without, and we observed interactive effects between plant and seed species identity on retention rates.

Seed trapping and retention rates are influenced by species identities and the physical attributes of plants and seeds. Because both processes can contribute to where a seed is ultimately dispersed, seed trapping and retention may mediate species co-occurrence and further species interactions.