Figure 4. Provenance differences in thermal safety margin (TSM) of four
tropical tree species grown under common environmental conditions. TSM
calculated using Tcrit as upper threshold in all panels,
with operating temperature defined as 32 °C (mean max air temperature of
the site) plus ∆Tleaf in (a), ∆Tcan in
(b), and ∆Tmod in (c). Ca = Castanospermum
australe, Hn = Homalanthus novo-guineensis, Me = Melicope
elleryana, and Tm = Terminalia microcarpa . Data is of tree
averages (n =6) presented as a box and whisker plots showing
median and interquartile range, with the average marked by ×. Results of
intraspecific t-test of provenance differences indicated by subscript
ns=not significant, * p < 0.05, ** p