Acorn germination is not enhanced near cache sites relative to random locations

Abstract

Acorns produced by oak (genus Quercus L.) trees are eaten by numerous wildlife species, many of which may also contribute to oak regeneration by dispersing acorns to favorable microhabitats. According to the directed dispersal hypothesis, seed dispersal agents may preferentially move seeds to locations that favor seedling establishment. As a case study of the directed dispersal hypothesis, we tested the hypothesis that vertebrate scatterhoarders preferentially cache acorns in locations where conditions favor germination. We planted acorns within 0.3 m of known cache sites (cache plots) and at paired random plots that were located at equal distances from the acorn source. We then monitored germination, seedling emergence, and growth over the first year. Acorns near actual cache sites germinated at lower rates than acorns in random sites, the opposite of what would be predicted by the directed dispersal hypothesis, but insufficient seedling survival prevented statistical analysis of survival and growth. These results do not support the directed dispersal hypothesis with regard to the microhabitat at cache plots, and do not address the effects of seed burial or the potential for longer term positive effects on survival of germinated seedlings.