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Timing of seed dispersal generates a bimodal seed bank depth distribution
Author(s) -
Espinar José L.,
Thompson Ken,
García Luis V.
Publication year - 2005
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.92.10.1759
Subject(s) - biology , soil seed bank , perennial plant , soil water , biological dispersal , salt marsh , dry season , agronomy , marsh , mediterranean climate , habitat , germination , ecology , wetland , population , demography , sociology
The density of soil seed banks is normally highest at the soil surface and declines monotonically with depth. Sometimes, for a variety of reasons, peak density occurs below the surface but, except in severely disturbed soils, it is generally true that deeper seeds are older. In seasonally dry habitats that develop deep soil cracks during the dry season, it is possible that some seeds fall down cracks and rapidly become deeply buried. We investigated this possibility for three dominant clonal perennials ( Scirpus maritimus , S. litoralis , and Juncus subulatus ) in the Doñana salt marsh, a nontidal marsh with a Mediterranean climate located in southwest Spain. Two species, which shed most of their seed during the dry season and have seeds with low buoyancy, had bimodal viable seed depth distributions, with peak densities at the surface and at 16–20 cm. A third species, which shed most seeds after soil cracks had closed and had seeds with high buoyancy, had viable seeds only in surface soil. Bimodal seed bank depth distributions may be relatively common in seasonally dry habitats with fine‐textured soils, but their ecological significance has not been investigated.

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