Contribution of Tcrit and Tleafto the thermal safety margin
Across all species and provenances, there was a significant, positive correlation between Tcrit and Tleaf(F 1,46 = 6.55, p = 0.014, n = 48) that represented a 0.4 °C increase in Tcrit per 1 °C increase in Tleaf (Supporting information S10). However, within-species, we did not find evidence for a correlation between Tcrit and Tleaf in any of the four species (p > 0.05, Supporting information S10). Species differed in the absolute magnitude that either Tcrit or Tleaf varied, as a result different variables contributed more to within-species variation in the thermal safety margin depending on the species (Figure 5). In C. australe and T. microcarpa , the within-species range of Tcrit was 1.3 and 1.4 times larger than the within-species range of Tleaf (respectively), and therefore contributed more to variation in the thermal safety margin for these species. In contrast, for M. elleryana and H. novo-guineensis, within-species variation in Tcrit was the weaker driver of changes in thermal safety margins, as Tcrit variation was 0.3 and 0.7 that of Tleaf.