Post-dispersal seed predation in the temperate rainforest of southeast Alaska

Abstract

Post-dispersal predation on seeds of vertebrate-dispersed plants (Rubus spectabilis, Oplopanax horridus, and Streptopus amplexifolius) of the temperate rainforest of southeast Alaska was experimentally examined comparing 'clean' seeds with seeds embedded in feces of bears, important dispersers in the area, and comparing also different microhabitats where seeds may be dropped or defecated. It was found that seed removal was significantly higher for clean seeds than for seeds within bear feces, and that levels of seed predation were similar for seeds under plants of the same species and for seeds under plants of other species. These results indicate that seed predators (presumably mostly rodents) use neither fecal material nor the presence of a conspecific plant as a clue to the location of seeds.