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Plant Ecology

, 200:117 | Cite as

Heat increases germination of water-permeable seeds of obligate-seeding Darwinia species (Myrtaceae)

  • Tony D. AuldEmail author
  • Mark K. J. Ooi
Article

Abstract

We examined the response of seeds to heat in four geographically restricted and one widespread species of shrubby Darwinia from the fire-prone region of southeastern Australia. These shrubs are killed by fire and rely on seed germination after a fire to maintain populations. We replicated the germination trials across several sites and several fruiting seasons for most species. Seeds had a high level of viability and were largely dispersed in a dormant state, except in D. glaucophylla, where seed dormancy varied significantly across fruiting seasons. The indehiscent fruit of all species readily imbibes moisture when wet and seeds are not considered to be ‘hard-seeded’. All species had increased seed germination in response to a limited range of heating temperatures (generally 80–100°C). Higher temperatures killed increasing proportions of seeds. This pattern was broadly consistent across species, population and seasons, although the proportion of seeds whose germination was promoted by heat varied from high (D. diminuta, D. fascicularis, D. glaucophylla) to moderate (D. biflora, D. procera). Our work highlights the importance of heat as a mechanism for influencing germination in species that are not hard-seeded. Consequently, soil temperatures during a fire should strongly influence post-fire germination levels in Darwinia. The roles of other cues that promote germination, i.e. smoke, seasonal temperatures and their interactions with heat, remain to be investigated.

Keywords

Australia Dormancy Fire Threatened species Seed banks 

Notes

Acknowledgement

Rachael Thomas and Maria Matthes provided invaluable assistance in the field and laboratory during this project.

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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Biodiversity ScienceDepartment of Environment and Climate Change (NSW)HurstvilleAustralia
  2. 2.Institute for Conservation Biology, School of Biological SciencesUniversity of WollongongWollongongAustralia
  3. 3.Department of Animal and Plant Sciences, Alfred Denny BuildingUniversity of SheffieldSheffieldUK

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