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Seed rain to tree fall gaps in a neotropical rain forest

Denslow, J.S.; Gomez Diaz, A.E.

Canadian Journal of Forest Research 20(5): 642-648

1990


ISSN/ISBN: 0045-5067
DOI: 10.1139/x90-086
Accession: 007775545

We monitored both the seed rain and fruit production in the vicinity of four recent tree-fall gaps in the old-growth forest at the La Selva Biological Station, Costa Rica. Seeds were collected in trays of seed-sterilized soil distributed throughout the center of the gaps and left in place for 2 months; seeds were identified from seedlings that subsequently germinated from the soil samples in the shade house. Composition and density of seeds germinating from the trays were spatially and temporally variable, obscuring any phenological pattern in either species diversity or abundances of seedfall. However, rates of seed input (49 seeds/ (M2 .cntdot. months)) were higher than previous estimates (0.5-5 seeds/ (m2 .cntdot. month)), which suggests a high turnover rate of soil seed stocks in forest species with short dormancy capacities. A small proportion of the seeds were from the pioneer species (2-33%), which were nevertheless likely dispersed from second-growth vegetation at least 750 m from the gaps. Most of the species were animal dispersed and only 35% of the species and 19-55% of the seeds recovered from the seed trays likely originated from plants fruiting within 50 m of the gap. These data demonstrated the input of a copious and diverse seedfall from widely scattered sources within lowland tropical rain forests.

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