Seed mass and summer drought survival in a Mediterranean-climate ecosystem
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We related seed mass to summer drought survival in a Mediterranean-climate ecosystem. Previous experimental evidence linking seed mass and survival under drought is limited and at times contradictory. We tracked summer drought survival among four families/subfamilies at a restoration site in southwestern Australia. We coupled these observations with a glasshouse experiment assessing the growth and root morphology of Acacia and Eucalyptus species, with a range of seed masses, under mild and severe drought compared with a well-watered control. Summer drought survival in the field increased with seed mass across all four families/subfamilies. Seedling root biomass and length increased with seed mass consistently across five harvests over 60 days. Initial survival of seedlings in the glasshouse increased with seed mass and decreased with drought, but there was no interaction between the two. Greater absolute root investment provides a mechanism for both short and longer-term drought survival. Within-species variation in root growth may also affect the relative versus absolute survival advantage of large-seeded species. The benefits of large seed mass for establishment under environmental hazards are often considered to be temporary. Our results show that seed mass was correlated with other traits, including root length, which in turn, increased longer-term drought survival. Traits correlated with seed mass should therefore be considered in explanations of the ecological effect of seed mass variation.
KeywordsAcacia Eucalyptus Corymbia Plant establishment Restoration Southwestern Australia
We thank Kellie Maher and Tim Morald for their help in the field and glasshouse and James Hallett for his comments. For access to the Gnangara restoration site we thank the Western Australian Department of Environment and Conservation, and particularly Clayton Sanders and Tracy Sonneman. LMH was supported by a Fulbright Postgraduate Fellowship.
- Abbott I, Dell B, Loneragan O (1989) The jarrah plant. In: Dell B, Havel JJ, Malajczuk N (eds) The jarrah forest: a complex mediterranean ecosystem. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp 41–52Google Scholar
- CSIRO (2007) Climate change in Australia: Technical Report 2007. CSIRO Publishing, Melbourne, AustraliaGoogle Scholar
- Groom PK (2002) Seedling water stress response of two sandplain Banksia species differing in ability to tolerate drought. J Mediterr Ecol 3:3–9Google Scholar
- Nicholls N (2006) Detecting and attributing Australian climate change: a review. Aust Meteorol Mag 55(3):199–211Google Scholar
- Nicotra AB, Babicka N, Westoby M (2002) Seedling root anatomy and morphology: an examination of ecological differentiation with rainfall using phylogenetically independent contrasts. Oecologia 130:136–145Google Scholar
- Paczkowska G, Chapman AR (2000) The Western Australian flora: a descriptive catalogue. Wildflower Society of Western Australia (Inc.), Western Australian Herbarium. CALM and the Botanic Gardens & Park Authority, Perth, AustraliaGoogle Scholar
- Salisbury EJ (1942) The reproductive capacity of plants. G. Bell and Sons, London, UKGoogle Scholar
- Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, New YorkGoogle Scholar
- Wann JM, Bell DT (1997) Dietary preferences of the black-gloved wallaby (Macropus irma) and the western grey kangaroo (M. fuliginosus) in Whiteman Park, Perth, Western Australia. J R Soc West Aust 80(2):55–62Google Scholar