Post-dispersal predation is a potentially significant modifier of the distribution of recruiting plants and an often unmeasured determinant of the effectiveness of a frugivore’s dispersal service.In the wet tropical ...Post-dispersal predation is a potentially significant modifier of the distribution of recruiting plants and an often unmeasured determinant of the effectiveness of a frugivore’s dispersal service.In the wet tropical forests of Austra-lia and New Guinea,the cassowary provides a large volume,long distance dispersal service incorporating benefi-cial gut processing;however,the resultant clumped deposition might expose seeds to elevated mortality.We exam-ined the contribution of post-dispersal seed predation to cassowary dispersal effectiveness by monitoring the fate of 11 species in southern cassowary(Casuarius casuarius johnsonii Linnaeus)droppings over a period of 1 year.Across all species,the rate of predation and removal was relatively slow.After 1 month,70%of seeds remained intact and outwardly viable,while the number fell to 38%after 1 year.The proportion of seeds remaining intact in droppings varied considerably between species:soft-seeded and large-seeded species were more likely to escape removal and predation.Importantly,across all species,seeds in droppings were no more likely to be predated than those left undispersed under the parent tree.We speculate that seed predating and scatter-hoarding rodents are responsible for the vast majority of predation and removal from droppings and that the few seeds which undergo secondary dispersal survive to germination.Our findings reinforce the conclusion that the cassowary is an impor-tant seed disperser;however,dispersal effectiveness for particular plant species can be reduced by massive post-dispersal seed mortality.展开更多
基金This study was undertaken as part of the Rainforest CRC and conducted under CSIRO Animal Ethics Approval OB15/12 and Queensland Department of Environment Scientific Purposes Permit FO/001071/96/SAB.
文摘Post-dispersal predation is a potentially significant modifier of the distribution of recruiting plants and an often unmeasured determinant of the effectiveness of a frugivore’s dispersal service.In the wet tropical forests of Austra-lia and New Guinea,the cassowary provides a large volume,long distance dispersal service incorporating benefi-cial gut processing;however,the resultant clumped deposition might expose seeds to elevated mortality.We exam-ined the contribution of post-dispersal seed predation to cassowary dispersal effectiveness by monitoring the fate of 11 species in southern cassowary(Casuarius casuarius johnsonii Linnaeus)droppings over a period of 1 year.Across all species,the rate of predation and removal was relatively slow.After 1 month,70%of seeds remained intact and outwardly viable,while the number fell to 38%after 1 year.The proportion of seeds remaining intact in droppings varied considerably between species:soft-seeded and large-seeded species were more likely to escape removal and predation.Importantly,across all species,seeds in droppings were no more likely to be predated than those left undispersed under the parent tree.We speculate that seed predating and scatter-hoarding rodents are responsible for the vast majority of predation and removal from droppings and that the few seeds which undergo secondary dispersal survive to germination.Our findings reinforce the conclusion that the cassowary is an impor-tant seed disperser;however,dispersal effectiveness for particular plant species can be reduced by massive post-dispersal seed mortality.
