Tree mortality predicted from drought-induced vascular damage

William R.L. Anderegg; Alan L. Flint; Cho-ying Huang; Lorraine E. Flint; Joseph A. Berry; Frank W. Davis; John S. Sperry; Christopher B. Field

doi:10.1038/NGEO2400

Tree mortality predicted from drought-induced vascular damage

Nature Geoscience

By: William R.L. Anderegg, Alan L. Flint, Cho-ying Huang, Lorraine E. Flint, Joseph A. Berry, Frank W. Davis, John S. Sperry, and Christopher B. Field

https://doi.org/10.1038/NGEO2400

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Abstract

The projected responses of forest ecosystems to warming and drying associated with twenty-first-century climate change vary widely from resiliency to widespread tree mortality^{1, 2, 3}. Current vegetation models lack the ability to account for mortality of overstorey trees during extreme drought owing to uncertainties in mechanisms and thresholds causing mortality^{4, 5}. Here we assess the causes of tree mortality, using field measurements of branch hydraulic conductivity during ongoing mortality in Populus tremuloides in the southwestern United States and a detailed plant hydraulics model. We identify a lethal plant water stress threshold that corresponds with a loss of vascular transport capacity from air entry into the xylem. We then use this hydraulic-based threshold to simulate forest dieback during historical drought, and compare predictions against three independent mortality data sets. The hydraulic threshold predicted with 75% accuracy regional patterns of tree mortality as found in field plots and mortality maps derived from Landsat imagery. In a high-emissions scenario, climate models project that drought stress will exceed the observed mortality threshold in the southwestern United States by the 2050s. Our approach provides a powerful and tractable way of incorporating tree mortality into vegetation models to resolve uncertainty over the fate of forest ecosystems in a changing climate.

Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Tree mortality predicted from drought-induced vascular damage
Series title	Nature Geoscience
DOI	10.1038/NGEO2400
Volume	8
Year Published	2015
Language	English
Publisher	Nature Publishing Group
Contributing office(s)	California Water Science Center
Description	5 p.
First page	367
Last page	371
Google Analytic Metrics	Metrics page