You are here

Temperature a critical factor in the germination of herbs in Kosciuszko National Park

 

Caption: Seed collector Andrew Orme in the Snowy Mountains.

Image: Euan Mills

 

Caption: Aciphylla glacialis (Mountain Celery) requires very low temperatures for germination.

Image: K. Downs

 

Caption: Euphrasia (Eyebright) is very difficult to germinate and requires further scientific investigation.

Image: K. Downs

 

Alpine ecosystems are very sensitive to environmental change and are particularly threatened by warming temperatures. For this reason, seed collectors Richard Johnstone and Andrew Orme collected seed from a variety of herbs growing at high altitude in Kosciuszko National Park, during phase 1 of the Millennium Seed Bank Project.

Germination specialist Amelia Martyn began a series of experiments to unlock the secrets of the alpine seeds, in a project funded by the Australian Flora Foundation and the Australian Native Plant Society, Canberra. Each species had a unique response to temperature, with some germinating during the chilling cycle at 5 °C, some requiring chilling followed by warm spring temperatures, and some indifferent to the temperatures tested. Two species were unable to germinate at all without chilling, while others germinated much faster and in far great numbers if they were chilled before exposure to warmer temperatures. The requirement for chilling makes these species particularly vulnerable to a warming climate.

Conservation scientist Karen Sommerville joined the team to examine the data for connections between seed characteristics and germination requirements. Seeds with tiny embryos surrounded by endosperm (nutritive tissue) were found to be most likely to require chilling. Seeds without endosperm tended to germinate at a wide range of temperatures whether previously chilled or not. Species in the latter group (including members of the Asteraceae and Rosaceae families) are likely to remain stable or expand in range under a warming climate. Species in the former group (including members of the Apiaceae and Campanulaceae families) are more likely to contract in range in response to warming temperatures, especially if they are already restricted to high-altitude sites. These species should be prioritised for seedbanking as an ‘insurance policy’ against their extinction in the wild.

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.