Turgor loss point predicts survival responses to experimental and natural drought in tropical tree seedlings

Liza Comita and 5 other contributors

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    Identifying key traits that can serve as proxies for species drought resistance is crucial for predicting and mitigating the effects of climate change in diverse plant communities. Turgor loss point (pi(tlp)) is a recently emerged trait that has been linked to species distributions across gradients of water availability. However, a direct relationship between pi(tlp) and species ability to survive drought has yet to be established for woody species. Using a manipulative field experiment to quantify species drought resistance (i.e., their survival response to drought), combined with measurements of pi(tlp) for 16 tree species, we show a negative relationship between pi(tlp) and seedling drought resistance. Using long-term forest plot data, we also show that pi(tlp) predicts seedling survival responses to a severe El Nino-related drought, although additional factors are clearly also important. Our study demonstrates that species with lower pi(tlp) exhibit higher survival under both experimental and natural drought. These results provide a missing cornerstone in the assessment of the traits underlying drought resistance in woody species and strengthen pi(tlp) as a proxy for evaluating which species will lose or win under projections of exacerbating drought regimes.