Evidence for a trade-off between growth rate and xylem embolism resistance in 22 Eucalyptus species

Within the growth-survival trade-off framework, embolism resistance is considered a contributor to survival, yet whether greater embolism resistance inherently limits growth remains unclear. We investigated this relationship among 22 Eucalyptus species spanning wide precipitation and temperature gradients, grown under controlled conditions for 6-10 months. We quantified embolism resistance (drought-induced stem P₅₀), growth, and wood anatomy. Our experimental results reveal a clear trade-off between embolism resistance and growth rate, consistently supported by both cross-species and phylogenetic (correlated-divergence) analyses. Faster growing species exhibited less negative P₅₀ and higher vessel lumen fraction, driven by wider vessels, enhancing hydraulic conductivity. Conversely, slower growing species had more negative P₅₀, characterised by thicker vessel walls and a greater density of narrower vessels, reducing hydraulic conductivity. P₅₀ and growth rate were significantly related to climate-of-origin, with species from drier or colder regions exhibiting greater embolism resistance and slower growth. Furthermore, we conducted a global vote-counting review of 34 studies, showing weak but context-dependent support for the growth rate-P₅₀ trade-off, with no evidence of concurrent faster growth and greater embolism resistance. These findings advance understanding of growth rate-embolism resistance trade-offs, reveal climatic adaptation mechanisms in woody species, and inform predictions of plant persistence under climate change.