Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe.
Drought-induced tree mortality has been observed globally and is expected to increase under climate change scenarios, with large potential consequences for the terrestrial carbon sink. Predicting mortality across species is crucial for assessing the effects of climate extremes on forest community biodiversity, composition, and carbon sequestration. However, the physiological traits associated with elevated risk of mortality in diverse ecosystems remain unknown, although these traits could greatly improve understanding and prediction of tree mortality in forests. We performed a meta-analysis on species' mortality rates across 475 species from 33 studies around the globe to assess which traits determine a species' mortality risk. We found that species-specific mortality anomalies from community mortality rate in a given drought were associated with plant hydraulic traits. Across all species, mortality was best predicted by a low hydraulic safety margin-the difference between typical minimum xylem water potential and that causing xylem dysfunction-and xylem vulnerability to embolism. Angiosperms and gymnosperms experienced roughly equal mortality risks. Our results provide broad support for the hypothesis that hydraulic traits capture key mechanisms determining tree death and highlight that physiological traits can improve vegetation model prediction of tree mortality during climate extremes.
Department of Biology, University of Utah, Salt Lake City, UT 84112; Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544; anderegg@utah.edu.
William R L
WR
Anderegg
Institute of Soil, Water, and Environmental Sciences, Agricultural Research Organization Volcani Center, 50250 Beit Dagan, Israel;
Tamir
T
Klein
Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095;
Megan
M
Bartlett
Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095;
Lawren
L
Sack
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544;
Adam F A
AF
Pellegrini
Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia;
Brendan
B
Choat
Institute of Systematic Botany and Ecology, Ulm University, 89081 Ulm, Germany.
Steven
S
Jansen
D055864:Droughts / Q000706:statistics & numerical data*; D017753:Ecosystem; D018526:Plant Transpiration / Q000502:physiology*; D013045:Species Specificity; D013312:Stress, Physiological / Q000502:physiology*; D014197:Trees / Q000145:classification* / Q000254:growth & development*
biodiversity; carbon cycle; climate change; climate extremes; meta-analysis