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Dryad

Figures for "California forest die-off linked to multi-year deep soil drying in 2012-2015 drought"

Data files

Jun 07, 2019 version files 3.34 GB

Abstract

Data underlying main figures in "California forest die-off linked to multi-year deep soil drying in 2012-2015 drought", published in Nature-Geoscience, July 2019, ML Goulden and RC Bales. 

Abstract of paper: Widespread episodes of recent forest die-off have been tied to the occurrence of anomalously warm droughts, though the underlying mechanisms remain inadequately understood. California’s 2012-2015 drought, with exceptionally low precipitation and warmth and widespread conifer death, provides an opportunity to explore the chain of events leading to forest die-off. Here we present the spatial and temporal patterns of die-off and moisture deficit during California’s drought based on field and remote-sensing observations.  We found that die-off was closely tied to multi-year deep-rooting-zone drying, and that this relationship provides a framework to diagnose and predict mortality. Marked tree death in an intensively studied Sierra Nevada forest followed a four-year moisture overdraft, with cumulative 2012-2015 evapotranspiration exceeding precipitation by ~1500 mm and subsurface moisture exhaustion to 5-15 m depth. Observations across the entire Sierra Nevada further linked tree death to deep drying, with die-off and moisture overdraft covarying across latitude and elevation. Unusually dense vegetation and warm temperatures accelerated southern Sierran evapotranspiration in 2012-2015, intensifying overdraft and compounding die-off by an estimated 55%. Climate change is expected to further amplify evapotranspiration and moisture overdraft during drought, potentially increasing Sierran tree death during drought by ~15 to 20% per oC.