Patterns of seed removal of fire-sensitive tree species in floodplain and upland sites in the absence of fire

Surface fire is the primary ecological filter maintaining eastern North American woodlands. However, fire is not the only filter affecting species demographics, and in the absence of fire, the influence of secondary filters, such as seed predators, increases. To explore how different seed predator guilds affect individual species, we established seed offerings examining the effects of predator type (invertebrates only and invertebrates + small mammals), forest type (upland and floodplain), season (fall and summer), and offering location (beneath conspecific and heterospecific focal trees) on seed removal of four fire-sensitive tree species at two sites in the southeastern United States. Additionally, we explored the effects of forest structure on seed removal. Excluding small mammals had no impact on seed removal for any species, indicating that invertebrates were the primary seed predator. Winged elm (32%) and sweetgum (31%) seed removal in the floodplains significantly exceeded red maple (15%) and loblolly pine (6%). In the uplands, sweetgum (68%), winged elm (64%), and red maple (55%) seed removal significantly exceeded that of loblolly pine (4%). Sweetgum seeds were removed more frequently than loblolly pine regardless of focal tree identity. However, seed removal of both species beneath conspecific focal trees did not significantly exceed that recorded beneath heterospecific trees. Competing vegetation height was highest in the uplands in the summer and was positively associated with sweetgum seed removal intensity. Collectively, these results suggest that loblolly pine seeds have the highest probability of avoiding seed predator removal, potentially increasing its odds of establishing on upland sites