2.2 Study species and plant material
We selected 16 tropical rainforest tree species (Figure 1, Table S1, Figure S1) that are commonly used in revegetation plantings in the Australian Wet Tropics bioregion (Engert et al. 2020), taxonomically diverse (representing 13 families), and exhibit a broad range of plant functional traits and successional strategies (Goosem & Tucker 2013). Plant material with verified coordinates or collection location descriptions were sourced from local nurseries including Cairns Regional Council, Rainforest Rescue, Douglas Shire Council, Tablelands Regional Council, and Kuranda Envirocare. For each species, we obtained 30 individual seedlings from either lowland or upland origin (n = 960 = 30 seedlings × 2 provenance × 16 species). For two species (Davidsonia pruriens and Syzygium kuranda ) only 15 seedlings could be sourced from a single upland maternal location so seedlings from an additional upland maternal location were included to make up the 30 total replicate seedlings needed (Table S1). During seedling handling and planting, we made sure plant provenance could be tracked back to the maternal plant location, however for this study we consider any plants originating from above 300 m a.s.l to be of ‘upland provenance’ and any plants originating from below this threshold to be of ‘lowland’ provenance in downstream analyses.
Across the focal species, the lowland and upland provenances differed in their MAT by on average 4.0 °C (range 1.8 to 5.8 °C) and by 836 mm in their MAP (range 102 to 1890 mm) (Table S1). Lowland and upland provenance collection locations were on average 105 km (range 52 to 150 km) apart (great-circle distance calculated with ‘geosphere’ package (Hijmans 2022)), with Lowland provenances sourced from the Daintree Rainforest and upland provenances sourced from the Atherton tablelands (with few exceptions). As such, the comparison between DRO and Thiaki planting sites represented a reciprocal transplant for many species.