Large and small acorns contribute equally to early-stage oak seedlings: a multiple species study

Abstract

Larger seeds generally produce larger seedlings either at intra- or at interspecific level; however, whether large seeds contribute more to seedlings than do small ones is largely unknown. We investigated fresh masses of acorns, seedling size, mobilization of cotyledonary reserves of nine red and white oak species (Quercus rubra, Q. falcata, Q. palustris, Q. phellos, Q. coccinea, Q. variabilis, Q. mongolica, Q. aliena and Q. acutissima) with contrasting acorn masses to investigate whether large seeds are better than small ones in supporting early-stage seedlings. Our study showed no significant effect of fresh acorn mass on seedling survival rates of the nine oak species at intra-specific level, though large acorns tended to produce large seedlings. Although acorn mass was positively correlated with seedling size (e.g., dry mass) both at intra- and at interspecific levels, large and small acorns allocated the same proportion of cotyledonary reserves into seedlings at intraspecific level. Moreover, variations in the proportion of mobilized cotyledonary reserves were not explained by fresh acorn mass at interspecific level. We also found that more soil-derived N was transferred into seedlings produced by small acorns than by large ones. Our results suggest that cotyledonary reserves in small and large seeds contribute equally to support their early-stage seedlings, but the role of large seeds may become more apparent later than the 50-day period of this experiment.