Evidence for a trade-off between growth rate and xylem embolism resistance in 22 Eucalyptus species
Pan T, Jacob V, Britton TG, Schrader J, Peters JMR., Li J, Zhang C, Wen J, Choat B and Wright IJ
New Phytologist
https://doi.org/10.1111/nph.71345
Summary
- 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.
