Seed predation limits post-fire recruitment in the waratah (<Emphasis Type="Italic">Telopea speciosissima</Emphasis>) |
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Authors: | Andrew J Denham |
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Institution: | (1) Institute for Conservation Biology and Law, School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia;(2) Terrestrial Biodiversity Science Section, Department of Environment and Climate Change NSW, P.O. Box 1967, Hurstville, NSW, 2220, Australia |
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Abstract: | Seed predation may reduce recruitment in populations that are limited by the availability of seeds rather than microsites.
Fires increase the availability of both seeds and microsites, but in plants that lack a soil- or canopy-stored seed bank,
post-fire recruitment is often delayed compared to the majority of species. Pyrogenic flowering species, such as Telopea speciosissima, release their non-dormant seeds more than 1 year after fire, by which time seed predation and the availability of microsites
may differ from that experienced by plants recruiting soon after fire. I assessed the role of post-dispersal seed predation
in limiting seedling establishment after fire in T. speciosissima, in southeastern Australia. Using a seed-planting experiment, I manipulated vertebrate access to seeds and the combined cover
of litter and vegetation within experimental microsites in the 2 years of natural seed fall after a fire. Losses to vertebrate
and invertebrate seed predators were rapid and substantial, with 50% of seeds consumed after 2 months in exposed locations
and after 5 months when vertebrates were excluded. After 7 months, only 6% of seeds or seedlings survived, even where vertebrates
were excluded. Removing litter and vegetation increased the likelihood of seed predation by vertebrates, but had little influence
on losses due to invertebrates. Microsites with high-density vegetation and litter cover were more likely to have seed survival
or germination than microsites with low-density cover. Recruitment in pyrogenic flowering species may depend upon the release
of seeds into locations where dense cover may allow them to escape from vertebrate predators. Even here, conditions suitable
for germination must occur soon after seed release for seeds to escape from invertebrate predators. Seed production will also
affect recruitment after any one fire, while the ability of some juvenile and most adult plants to resprout after fire buffers
populations against rapid declines when there is little successful recruitment. |
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Keywords: | Fire Proteaceae Pyrogenic flowering Seed predators Seedling establishment |
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