Climatic Correlates of Tree Mortality in Water- and Energy-Limited Forests

• DOI: 10.1371/journal.pone.0069917
• Publication Date: 2013-07-25T22:22:02Z
• Authors: Adrian J. Das; Nathan L. Stephenson; Alan Flint; Tapash Das; Phillip J. van Ma...
• Keywords: Vulnerability; Elevation (ballistics); Tree (set theory)

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