Constraints of seed size on plant distribution and abundance

We examined the correlation between seed size (mass) and spatial and tempor al distribution and abundance of plants, using both published data from nor thern England and 18 years of census data from permanent quadrats in the Ch ihuahuan Desert, Arizona, USA. In both systems, there were many small-seede d species and few large-seeded ones. Spatial patterns of distribution and a bundance were constrained by seed size within triangle envelopes, i.e., sma ll-seeded species had a greater range of abundance and a greater number of sites occupied than did large-seeded species. Temporal patterns of abundanc e and distribution from the Chihuahuan Desert site were similarly correlate d with seed size, i.e., small-seeded species were, in general more abundant and present in more than were large-seeded species. These patterns probabl y result because small-seeded species produce more seeds. are more vagile, and persist longer in seed banks than do large-seeded species. The results are consistent with recent findings from seed bank studies, suggesting the generality of the correlation between seed size and plant abundance and dis tribution.