Foliar freezing resistance of Australian alpine plants over the growing season
Article first published online: 18 APR 2012
© 2012 The Authors. Austral Ecology © 2012 Ecological Society of Australia
Volume 38, Issue 2, pages 152–161, April 2013
How to Cite
VENN, S. E., MORGAN, J. W. and LORD, J. M. (2013), Foliar freezing resistance of Australian alpine plants over the growing season. Austral Ecology, 38: 152–161. doi: 10.1111/j.1442-9993.2012.02387.x
- Issue published online: 21 MAR 2013
- Article first published online: 18 APR 2012
- Accepted for publication March 2012.
- chlorophyll fluorescence;
- frost tolerance;
- snow cover;
- snowmelt date
We assessed the freezing resistance of leaves ex situ of 25 Australian alpine plant species. We compared the freezing resistance of forb, graminoid and shrub species from three alpine summits of different altitudes; from a low altitude site just above treeline, to a fully alpine tundra site. Foliar freezing resistance (LT50) in spring varied from −5.9°C to −18.7°C and standardized LT50 values within species were significantly related to site altitude. Additionally, when comparing all the species in the study, freezing resistance was significantly related to site; the LT50 of samples from a low-altitude summit (1696 m) were significantly lower than those of samples from mid- (1805 m) and high-altitude (1860 m) summits. The LT50 of juvenile foliage did not differ significantly from that of adult foliage. Shrubs were highly resistant to freezing. At the highest summit, we examined the course of seasonal freezing resistance from early summer to early autumn across three alpine plant communities that differed in the time of natural snowmelt; from sheltered (snowpatch) to exposed (open heath). No differences in freezing resistance over the growing season were detected for exposed or sheltered communities and there were no consistent trends indicating frost hardening over the growing season. Overall, the common Australian alpine species we investigated appear well adapted to freezing conditions throughout the snow-free growing season. We have no evidence to suggest that freezing temperatures soon after snowmelt in spring are especially damaging to the alpine plants at these summits.