Seed mass, seed dispersal capacity, and seedling performance in a Pinus sylvestris population

Seed size optimization theories are generally based on the assumption that seed mass increases seedling performance and decreases seed dispersal ability. In this paper, we investigated the relationship between seed mass, wing area, and seed terminal velocity in a wind-dispersed tree, Pinus sylvestris, and we asked whether these morphological seed measurements are related to seedling performance. As predicted by the isometry hypothesis, we found that seed shape remained constant as size varied. This constancy in seed shape has two major consequences: i) seed mass is negatively related to seed dispersal capacity, and ii) traits related to dispersal varied in a much narrower range than seed mass. Seed mass also had a positive effect on emergence rate and seedling growth up to 6 months; this did not result from any family effect. However, the low variation of seed terminal velocity led to no statistical relationship between seed dispersal capacity and seedling performance.