Seed floating ability and distribution of alpine plants along a northern Swedish river

Abstract. In this study we tested the hypothesis that diaspore buoyancy is an important factor in determining the distribution range of riparian plants, by measuring the floating capacity of fruits and seeds from 17 alpine vascular plant species during 1 yr. Minimum, median, mean, and maximum (≤ 1 yr) floating times of fruits and seeds were then related to the downstream distribution of plants along the free‐flowing Vindel River in northern Sweden. The distances from the alpine headwater region to the most downstream occurrence of plants, and to the cessation of a more continuous distribution, were evaluated. The variation in downstream limits of plants could not be statistically explained by variation in seed buoyancy between species, indicating that floating ability of seeds is not important for plant distribution patterns. There may be several reasons for this, and they may differ between species.