Foliar freezing resistance of Australian alpine plants over the growing season

Abstract

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.

Metabolic and physiological responses of Mediterranean high‐mountain and alpine plants to combined abiotic stresses

“…Snow cover, plant‐to‐plant positive interactions with neighbors (i.e. facilitation) and microclimate heterogeneity can also influence freezing tolerance in alpine species (Venn et al , Briceño et al ). In any case, the effects diverge among life forms, phenology and geographical location.…”

Individual Cryptomeria fortunei Hooibrenk Clones Show Varying Degrees of Chilling Stress Resistance

“…Previous studies have shown that cold treatment on LT-sensitive plants accelerates their electrolyte flow and increases permeability of cellular membranes, leading to serious membrane damage and "membrane leakage" phenomena [7]. The intracellular concentration of ions and organic substances can be used to measure electrolyte leakage (EL) levels [8,9]; EL levels and the semi-lethal temperature (LT 50 ) caused by freezing stress have been widely used for the diagnosis of cold resistance [10][11][12]. Plant photosynthesis is sensitive to temperature.…”

Effects of the duration of cold stratification on early life stages of the Mediterranean alpine plantSilene ciliata

“…Variation in snow cover duration along altitudinal gradients has promoted different adaptations in many alpine plants, such as the generation of frost resistance (Venn et al 2013) or the development of clonal traits (Evette et al 2009). However, reduced snow cover duration may increase the frequency of topsoil freezing events in late spring (Kreyling 2010), damaging seedlings and adult plants (e.g.…”