4.4 Conclusions and implications for rainforest restoration in
the Australian Wet Tropics
Although site and provenance effects were important in determining tree
survival and growth across our 16 study species, evidence for local
adaptation was mixed. For most species the lowland provenance performed
better than the upland provenance regardless of site, and provenance
differences were generally stronger in faster growing species. This
highlights the complexity and context-dependency of local adaptation in
tropical rainforest trees, challenging the ‘local is best’ strategy for
sourcing seed for restoration plantings (Cooper et al. 2018). Our
findings suggest that using lowland provenances, regardless of site,
could optimize initial plant growth in some species. Restoration
practitioners might consider expanding the sources of seed, particularly
in higher altitude sites like the Atherton Tablelands, to meet seed
demands and enhance genetic diversity and adaptive capacity. However,
risks associated with both local and mixed provenancing approaches are
well-documented (Jordan et al 2024). Future research at this site
includes investigating whether observed growth responses evident here
can be explained by variation of physiological traits, or whether
trade-offs exist with growth and tolerance to heat (Middleby et al.
2024b) or drought stress. We urge researchers and practitioners in this
region to focus on generating the necessary information for informed
decision-making.