Plants can survive disturbance by withstanding damage (resistance) or recovering after damage (resilience). Plant functional traits, like wood density (WD) and specific leaf area (SLA), have been shown to mediate this trade-off for some disturbances, but not for frost. Frost is a rare event in undisturbed tropical rainforest, but does occur seasonally on the Atherton Tablelands, Queensland, Australia, where much of the rainforest is fragmented. It is possible that severe frost events will increase in frequency and intensity as a result of climate change. This study examined the effects of a severe frost that occurred in June and July of 2007 on restoration plots of riparian rainforest seedlings. We quantified frost resilience three months after the frost event, by measuring on individuals that had lost 100% of foliage from the frost: 1) proportion of individuals alive within a species, 2) mean number of shoots, and 3) length of the longest shoot. SLA, WD, and phenology (evergreen vs. deciduous) were then compared to these variables to determine whether these traits were associated with frost resilience. We also measured plant mortality. We studied 79 individuals from 10 species. This study complements another that linked frost resistance to several plant functional traits.
Results/Conclusions
As predicted, SLA was positively correlated with resilience. Surprisingly, WD had no relationship with resilience. Leaf phenology determined the influence of WD on the resilience of a species, with low WD deciduous species more resilient to frost and evergreens showing low resilience independent of WD. Similarly, high SLA deciduous species were more resilient to frost, while evergreens showed low resilience independent of SLA. Overall, deciduous species drove the trends in resilience. Taken with a parallel study of frost resistance, this suggests a life-history tradeoff in WD and SLA. These findings have important implications for restoration plantings in frost prone areas; we recommend resilient deciduous species or resistant evergreens. This study and others like it may be instrumental in helping to build a global synthesis of functional ecology, to aid the accurate construction of future climate change vegetation models.
