Plant functional traits associated with frost susceptibility

Abstract

Frost can affect the productivity and distribution of plants, as it can cause plant cell rupture and xylem cavitation, which may limit the water transport, growth, and survival of plants. Climate change is expected to increase the effect of frost on plants, making them more susceptible to frost events. Therefore it is necessary to determine the frost susceptibility of species, which may be done using a plant functional trait approach. Plant functional traits are any attribute of a plant which can influence its establishment, survival and fitness. Frost tolerant species are expected to possess traits that reflect a conservative life history strategy aimed at stress tolerance, such as small and thick leaves, low specific leaf area, high leaf dry matter content, high leaf vein density and vein length per unit area, and high wood density. We sampled twenty-three plant species in Australia and twenty-five plant species in New Zealand, and compared their functional traits to existing species-specific frost susceptibility datasets. The traits most likely to influence frost susceptibility appear to be leaf size traits, leaf venation traits, and wood density, which is most likely due to the important effects these traits have on plant hydraulics, which is known to be significantly impacted by frost. Higher leaf vein density and vein length per unit area provide greater leaf hydraulics and better water use efficiency, which helps plants survive the water stress conditions that can be caused by frost. Higher wood density is related to having narrow xylem vessels, which are more resistant to freeze-thaw induced xylem cavitation and embolism, compared to wider xylem vessels. This study has provided globally-new information about which plant functional traits may be associated with frost susceptibility in plant species, and demonstrates for the first time the promise of leaf venation traits as a means of predicting and understanding response of plants to frost.