Botanic Gardens Trust, Sydney, Australia

Seed germination of high-altitude species in the Australian Alps

Dr Karen Sommerville - Scientific Officer, Dr Amelia Martyn - Seed Research Officer, Dr Cathy Offord - Manager Horticultural Research

Little is known about the seed biology of individual herbs growing at high altitudes in the Australian Alps. It is not known, for example, which species require low temperatures and/or cold stratification for germination and dormancy break, and whether these requirements would be fulfilled in a warmer climate. In this study, we investigated optimum temperatures for germination, and response to dormancy alleviating treatments, for 20 species collected from high altitudes (860-1960 m elevation) in Kosciuszko National Park.

Germination responses were highly variable among species. In terms of total germination, the seven Asteraceae species tested germinated well at a wide range of temperatures and showed little or no response to either cold stratification or the application of gibberellic acid. Five species from other families showed a significant increase in total germination across a range of temperatures following cold stratification, but only two of these (Aciphylla simplicifolia and Viola betonicifolia) failed to germinate at any temperature without prior cold stratification. A warming climate may be detrimental to these two species. For Acacia pravissima, Derwentia perfoliata, Euchiton involucratus and Poa hiemata, however, cold stratification led to a reduction in total germination. A warming climate may thus be beneficial to these species. 

This study has enabled us to determine the optimum conditions for germination for 20 high altitude species and has given us some insight into how the species may be affected by climate change. These outcomes will improve our ability to utilise the seed for rehabilitation, to test the viability of seedbank collections over time, and potentially contribute to models of the effects of climate change on vegetation in the Australian Alps.

Reference

  • Sommerville, K.D., Martyn, A.J. and Offord, C.A. (2013) Can seed characteristics or species distribution be used to predict the stratification requirements of herbs in the Australian Alps? Botanical Journal of the Linnean Society 172: 187-204.

Aciphylla-glacialis
High altitude species Aciphylla glacialus. Photo: Kathy Downs

Germination of Aciphylla glacialis

Germination of Brachyscome tenuiscapa var. purpurascens

Germination of Aciphylla glacialis (top) Brachyscome tenuiscapa var. purpurascens (bottom) seed following 0, 4, 8 and 12 weeks’ stratification.