Soil seedbank composition and dynamics across alpine summits in south-eastern Australia
Susanna E. Venn A B C and John W. Morgan AA Department of Botany, La Trobe University, Kingsbury Drive, Bundoora, Vic. 3086, Australia.
B New South Wales National Parks and Wildlife Service, Snowy Mountains Region, PO Box 2228, Jindabyne, NSW 2627, Australia.
C Corresponding author. Email: Susanna.Venn@environment.nsw.gov.au
Australian Journal of Botany 58(5) 349-362 https://doi.org/10.1071/BT10058
Submitted: 2 March 2010 Accepted: 4 June 2010 Published: 21 July 2010
Abstract
Alpine soil seedbanks are generally regarded as small and unimportant to regeneration. Here, we investigate for the first time the composition of the readily germinable soil seedbank across alpine summits in south-eastern Australia. We aimed to compare the species in the seedbank with the standing vegetation, show seasonal variations in seedbank composition and identify regeneration strategies of alpine seedbank species. By using standard glasshouse and cold-stratification germination techniques, the germinable soil seedbank across the study region was found to comprise 39 species from 25 families, with species from the Asteraceae the most common. Persistent seedbanks were found across all eight alpine summits (1668–1970 m), comparable in seed density (150 ± 27 to 1330 ± 294 per m2) with those of other alpine areas in the northern and southern hemispheres. The density of germinable seeds varied widely among sites and between collection times (autumn, spring) and there were no trends in seed density with altitude. The qualitative and quantitative similarity between the seedbank species and the standing vegetation was low. Correlations between the proportions of species in regeneration categories (from obligate seeders, through to vegetative regenerators) in the standing vegetation and the seedbank were also poor. Our results indicate a divergence between the species in the current standing vegetation and those present in the readily germinable soil seed bank. The current patterns and predominance of seed-regenerating species in the seedbank indicate that these species may have an important role to play in regulating and contributing to future changes in the vegetation assemblage.
Acknowledgements
This research was conducted under Permit No. 10002497 (Department of Sustainability and Environment). Seraphina Cutler, Sam Grover, Paul Smart, Nathan Wong, James Martindale Shannon, John Venn and Elizabeth Venn helped undertake the fieldwork, often under trying conditions. Sam Grover assisted in the glasshouse. Andrew Markwick (Parks Victoria) provided logistical support. Keith McDougall, Gemma Hoyle, Sam Grover and Ken Green greatly improved early versions of the manuscript. Two anonymous referees provided valuable comments. The Holsworth Wildlife Research Fund, Australian Geographic Society, the Ecological Society of Australia, and the Department of Botany at La Trobe University provided financial support. S. V. was supported by an Australian Postgraduate Award.
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