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Climatic correlates of tree mortality in water- and energy-limited forests

July 25, 2013

Recent increases in tree mortality rates across the western USA are correlated with increasing temperatures, but mechanisms remain unresolved. Specifically, increasing mortality could predominantly be a consequence of temperature-induced increases in either (1) drought stress, or (2) the effectiveness of tree-killing insects and pathogens. Using long-term data from California’s Sierra Nevada mountain range, we found that in water-limited (low-elevation) forests mortality was unambiguously best modeled by climatic water deficit, consistent with the first mechanism. In energy-limited (high-elevation) forests deficit models were only equivocally better than temperature models, suggesting that the second mechanism is increasingly important in these forests. We could not distinguish between models predicting mortality using absolute versus relative changes in water deficit, and these two model types led to different forecasts of mortality vulnerability under future climate scenarios. Our results provide evidence for differing climatic controls of tree mortality in water- and energy-limited forests, while highlighting the need for an improved understanding of tree mortality processes.

Publication Year 2013
Title Climatic correlates of tree mortality in water- and energy-limited forests
DOI 10.1371/journal.pone.0069917
Authors Adrian J. Das, Nathan L. Stephenson, Alan Flint, Tapash Das, Phillip J. van Mantgem
Publication Type Article
Publication Subtype Journal Article
Series Title PLoS ONE
Index ID 70124440
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center; Western Ecological Research Center