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

Citation

Goulden, Michael; Goulden, Michael (2019), Figures for "California forest die-off linked to multi-year deep soil drying in 2012-2015 drought", UC Irvine Dash, Dataset, https://doi.org/10.7280/D1DH3B

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.

Methods

See Methods section of paper and figure captions for details.

Usage Notes

The datasets posted here provide the values underlying the paper's figures. 

File "Goulden and Bales 2019 NDMI masked (Fig S1e).tif" is a geotiff in lat-long WGS84 of the late dry-season Delta Normalized Difference Moisture Index (Delta NDMI; 2009-11 NDMI minus 2016; units are dimensionless NDMI, which ranges from -1 to 1).  The figure was used to generate Fig S1e in the paper's supplement and was used for subsequent analyses.  The data set was masked with -999 as described in the Fig S1e caption of the paper's supplement.

File "Goulden and Bales 2019 P-ET (Fig S1c).tif" is a geotiff in lat-long WGS84 of the cumulative 4-year moisture overdraft (P-ET; 2012-15 sums; units are mm).  The figure was used to generate Fig S1c in the paper's supplement and was used for subsequent analyses.  The data set was masked to exclude water bodies.

File "Goulden and Bales Figures.xlsx" is an MS Excel 2010 file that includes the datasets used to generate all of the main figures in the paper.  The data for each figure is shown in a separate tab identified by the figure number.   The units and column headers are consistent with those used in the figures, except for a few cases where some of the vegetation indices were multiplied by 10000.  

 

Funding

National Science Foundation,

U.S. Department of Agriculture,

UC lab fees,