Provenance level differentiation in leaf traits and stomatal conductance
Provenance effects on leaf width differed across species. For H. novo-guineensis , there was strong evidence that provenances differed in leaf width (t (10) = −4.27, p = 0.00163), with leaves from the lowland provenance substantially narrower than leaves from the upland provenance, averaging 10.0 cm ± 1.3 and 15.2 cm ± 2.7 respectively (Figure 1a). There was no evidence of a provenance effect in leaf width for C. australe (t (10) = −0.16, p = 0.87, Figure 1a),M. elleryana (t (10) = 0.81, p = 0.44), or T. microcarpa (t (10) = 0.49,p = 0.64, Figure 1a).
The mean stomatal conductance (g s) measured around midday was 311 mmol m2 s-1and ranged from 71 to 700 mmol m2s-1 across all species and provenances (Figure 1b). For all species, mean g s was lower in the lowland provenance than the upland provenance, however moderate evidence for a provenance effect on g s was found only inT. microcarpa (t (10) = −2.25, p = 0.0479), in which g s averaged 248 mmol m2 s-1 ± 83 in the lowland provenance and 416 mmol m2 s-1 ± 163 for the upland provenance (Figure 1b).
Mean leaf inclination angle was 32.1 ° and ranged from 4.5 to 65.7 ° across all species and provenances (Figure 1c). For C. australe , we found strong evidence that leaves from the lowland provenance had steeper leaf angles than the upland provenance (t (10) = 3.64, p = 00454), averaging 51.7 ° ± 9.1 for the lowland provenance and 33.2 ° ± 8.5 for the upland provenance (Figure 1c). In H. novo-guineensis , we found strong evidence for the opposite pattern (t (10) = −3.83,p = 0.00333), with the lowland provenance having shallower leaf angles than the upland provenance, averaging 24.8 ° ± 14.7 and 52.9 ° ± 10.3 respectively (Figure 1c). We found no evidence for a provenance effect on leaf inclination angle for T. microcarpa or M. elleryana (p > 0.05, Figure 1c).
The mean thermal time constant was 7.5 s and ranged from 2.3 to 19.9 s. For all species, the thermal time constant of the lowland population was lower on average than the upland provenance (Figure 1d). However, we found strong evidence of a provenance effect only for H. novo-guineensis (t (10) = −3.45, p = 0.00619) which had a thermal time constant of 9.3 s ± 1.4 for the lowland provenance and 14.2 s ± 3.2 for the upland provenance.