DIFFERENTIAL POSTDISPERSAL SEED PREDATION IN DISTURBED AND INTACT TEMPERATE FOREST

Postdispersal seed predation on six native plant species was examined in an area of disturbed hardwood forest and in adjacent intact forest in eastern Pennsylvania. The study was conducted for 21 days in October and 24 days in November 1992, 3 yr after a tornado created a large gap by uprooting most of the canopy trees within a 2-ha area; the remainder of the forest was undisturbed. We used three species with seeds longer than 1 cm and three with seeds shorter than 1 cm in order to test the prediction that seeds of large-seeded species are consistently preferred. The magnitude and rate of seed predation were compared among species, between habitats and between months. In October, there was severe predation on all six species in the gap, but the large-seeded species experienced more seed predation than did small-seeded species in the forest. The magnitude of seed predation did not differ among species in either habitat in November. The magnitude of seed predation declined between October and November but much more so in the forest than in the gap, perhaps due to a covering of leaf litter that accumulated during the experiment. Seed predation rates differed among species but were generally higher in the gap and during the October experiment. These results show strong spatial and temporal patterns in seed predation and suggest that dispersal from the gap into the adjacent forest would prove beneficial for establishment provided that growing conditions there are suitable or that seeds are capabIe of remaining dormant until suitable conditions occur.