Steep slopes promote downhill dispersal of Quercus crispula seeds and weaken the fine-scale genetic structure of seedling populations

Abstract

The seed dispersal patterns and genetic structure of plant populations in mountainous forests may differ from those on flat sites, because some seeds that fall from adults are likely to roll downhill, and thus cause the seed shadows from different mother trees to merge. In the study reported here we used six polymorphic microsatellite markers to track seed dispersal and examine the fine-scale spatial genetic structure of adults and first-year seedlings of Quercus crispula in 2500 m2 plots on four slopes. In each of the four plots, leaves of adults, seedlings and endocarps of hypogeal cotyledons attached to the seedlings were genotyped to identify the seedlings' mother trees. The results showed that steeper slopes result in larger dispersions and smaller genetic structure of seedlings. These findings are a crucial step towards an understanding of the effect of topography on tree regeneration. © INRA, EDP Sciences, 2007.