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A surplus of seeds: High rates of post-dispersal seed predation in a flooded grassland in monsoonal Australia

Wurm, P.A.S. (1998). A surplus of seeds: High rates of post-dispersal seed predation in a flooded grassland in monsoonal Australia. Australian Journal of Ecology,23(4):385-392.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 11 times in Scopus Article | Citations

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Title A surplus of seeds: High rates of post-dispersal seed predation in a flooded grassland in monsoonal Australia
Author Wurm, P.A.S.
Journal Name Australian Journal of Ecology
Publication Date 1998
Volume Number 23
Issue Number 4
ISSN 0307-692X   (check CDU catalogue open catalogue search in new window)
eISSN 1440-1657
Scopus ID 2-s2.0-17444395267
Start Page 385
End Page 392
Total Pages 8
Place of Publication United Kingdom
Publisher Wiley-Blackwell Publishing Asia
HERDC Category C1 - Journal Article (DEST)
Abstract Oryza meridionalis is an annual emergent wetland grass which produces between 26 and 260 kg seeds ha-1 annually. Seed shed occurs at the end of the wet season, when the plains are usually still partially flooded. The juvenile recruitment of key native vertebrate species, such as the Magpie Goose (Anseranus semipalmata) and the Dusky Plains Rat (Rattus colletti), coincides with seed shed. This study investigated predation of O. meridionalis seeds at two sites on the South Alligator River floodplain in monsoonal Australia. The effects of inundation and the presence of a background density of seeds on seed removal were investigated by stratified sampling with respect to position down the topographic slope, to include the 'dry' floodplain margin, 'damp' Oryza zone, and 'flooded' Oryza zone. The effect of seed lot size on the proportion of seed removed was also investigated, and exclosures were used to identify the principal predator group. The proportion of seeds removed was not affected by the presence/absence of a background of seeds nor the number of seeds placed in experimental 'lots'. The majority of seeds (75%) was consumed by vertebrate predators (most likely the abundant Dusky Plains Rat). Inundation afforded some protection from predation. Despite high losses of seeds exposed to predators, O. meridionalis is an abundant and widespread species on these floodplains, possibly because of the protection from predation afforded by inundation to those seeds which are shed into the water column. It is likely that there is a complex interaction between topography, rainfall and predator and prey relationships, which ultimately determines the importance of seed removal for the maintenance of populations of O. meridionalis. These high losses of seeds to predation have implications for wetland rehabilitation where seed broadcasting is proposed.
Keywords Grassland
Kakadu National Park
Oryza meridionalis
Seed predation
Tropical wetland
Vertebrate seed predators
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