“…The sensitivity of growth to inter-annual variation in rainfall amount is weakest in the most mesic biome we examined (i.e., the wet-tropical KOR site had the lowest R 2 and slope); however, the variance explained (R 2 ) is within the range that has been found for trees growing in mesic biomes elsewhere (>1,700 mm; e.g., [61][62][63]). The relatively weak R 2 at KOR may be partially explained by our selection of a short 4-month 'growing season' Mar-Jun), which potentially doesn't fully capture the rainfall period that is most important to growth in the wet tropics; that is, rainfall in the transitional months both before (Sep-Nov) and after (Mar-Jun) the main wet season (Fig 2A ; see also [31]). Including the pre-wet season months (Sep-Nov) in 'growing season' rainfall totals for KOR does improve the variance in RWI explained by rainfall amount (by 8%), but does not significantly alter the negative-asymmetric shape or slope of the relationship between tree growth and rainfall amount (S4 Fig) . In addition, our finding, along with others [24,31,64,65] that the seasonal timing, duration and frequency of rainfall are as important (perhaps more so) for driving growth of C. columellaris as the total amount of rainfall in the wet tropics of Australia (>1,200 mm annual rainfall) may also partially explain the relatively weak relationship between growth and rainfall amount.…”