3.2 Provenance and site patterns in growth
The total explained variance of generalised linear models on growth
ranged from R 2 = 0.42 to 0.84 across species.
Overall, both site and provenance had strong effects on growth. Across
the ~17 months, saplings grew on average 1.0±0.7 and
1.1±0.9 m at Cow Bay and Thiaki respectively but 2.6±1.8 m at the DRO,
with an average growth of some species at the DRO (i.e. E.
grandis , H. novoguineensis , and T. microcarpa ) being
3b, Table 2, Figure S4), with all species except N. dealbata showing significant site effects. All species exhibited greater growth
at the DRO site compared to Cow Bay or Thiaki. For five species,
provenance had a significant impact on height increment (Figure 3b), and
in each species, the lowland provenance was taller than the upland
provenance. Only two species (H. novo-guineensis , S.
kuranda ) showed significant provenance × site effects on height
increment, with a greater difference between provenances at the two
lowland sites, than at Thiaki.
The strong influence of site was also evident when assessing inherent
growth rates, with all but three species (M. viminalis, N.
dealbata , and S. kuranda ) generally having higher inherent
growth rates at the lowland DRO site compared to the upland Thiaki site
(Figure 3c, Table 3, Figure S5). When assessing inherent growth rates, a
higher proportion of species (8/14) had significant provenance effects,
with most of those effects indicating higher inherent growth rate of
lowland provenances compared to upland provenances (Figure 3c, Table 3,
Figure S5). The exceptions were M. elleryana , S. kuranda ,
and T. microcarpa , where upland provenances had higher inherent
growth rates (except for at the lowland sites in M. elleryana ).