The importance of propagule predation in a forest of non-indigenous mangrove trees

Predation on propagules of Rhizophora mangle was compared in forests where this species is non-indigenous (Hawai'i, USA) and where it is native (Ameri can Samoa). Tree density and basal area of the non-indigenous stand were in termediate when compared to natural stands in other places where Rhizophora is common. Propagules were tethered on the forest floor at both sites for 14 days, predation was recorded, and survival rates of both attacked and co ntrol individuals were determined by placing them in a mist room. Mortality was significantly greater in American Samoa ((x) over bar = 25%) than in H awai'i (x) over bar = 8%). The lower effectiveness of the non-indigenous pr edators in Hawai'i may help explain the unusually high rate at which R. man gle propagules become established there.