SEED RAIN TO TREE-FALL GAPS IN A NEOTROPICAL RAIN-FOREST

In 4 recent tree-fall gaps in the old-growth forest at the La Selva biological Station, Costa Rica, seeds were collected in trays of soil distributed throughout the center of the gaps and left in place for 2 months. Composition and density of seeds germinating from 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.month)) were higher than previous estimates (0.5-5 seeds/(m2.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 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. -from Authors