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Predator satiation and recruitment in a mast fruiting monocarpic forest herb

Tsvuura, Zivanai, Griffiths, Megan E., Gunton, Richard M. and Lawes, Michael J. (2011). Predator satiation and recruitment in a mast fruiting monocarpic forest herb. Annals of Botany,107(3):379-387.

Document type: Journal Article

IRMA ID 82057923xPUB5
Title Predator satiation and recruitment in a mast fruiting monocarpic forest herb
Author Tsvuura, Zivanai
Griffiths, Megan E.
Gunton, Richard M.
Lawes, Michael J.
Journal Name Annals of Botany
Publication Date 2011
Volume Number 107
Issue Number 3
ISSN 0305 7364   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-79952165207
Start Page 379
End Page 387
Total Pages 9
Place of Publication London
Publisher Oxford University Press
HERDC Category C1 - Journal Article (DIISR)
Abstract Background and AimsCross-pollination and satiation of seed predators are often invoked to explain synchronous mast reproduction in long-lived plants. However, explanations for the synchronous death of parent plants are elusive. The roles of synchronous seeding and post-reproductive mortality were investigated in a perennial monocarpic herb (Isoglossa woodii) in coastal dune forest in South Africa.MethodsPre-dispersal seed predation and seed production were assessed by measuring fruit and seed set of inflorescences sprayed with insecticide or water and with no spray treatments. Seed predation was measured at different densities of I. woodii plants by monitoring removal rates of seed from the forest floor. The influence of adult plants on establishment of I. woodii seedlings was assessed by monitoring growth and survivorship of seedlings in caged and uncaged 1 × 1 m plots in understorey gaps and thickets.Key ResultsFruit and seed set were similar between spray treatments. An I. woodii stem produced 767·8 ± 160·8 seeds (mean ± s.e.) on dune crests and 1359·0 ± 234·4 seeds on the foredune. Seed rain was greater on the foredune than in other topographic locations. Seed predation rates were 32 and 54 on dune crests and in dune slacks, respectively, and decreased with seed abundance, number of inflorescences per stem and plant height. Seedling recruitment was greater beneath synchronously dying adult plants than in natural understorey gaps (no I. woodii). However, seedling growth rate beneath I. woodii mid-way through its life-cycle was less than in gaps, although survivorship was similar.ConclusionsThe selective advantage of masting in I. woodii derives from satiation of both pre- and post-dispersal seed predators. In addition, post-seeding mortality of adult plants facilitates seedling establishment. Satiation of seed predators and the benefits of seedling establishment are strong drivers of the evolution of synchronous monocarpy in I. woodii.
Keywords Isoglossa woodii
seed predation
seedling establishment
Synchronous flowering
understorey gaps
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Created: Fri, 17 Jan 2014, 00:49:58 CST