Flake and Weisberg PJ mortality raw data

Data used for Flake and Weisberg (accepted) Fine-scale stand structure mediates drought-induced tree mortality in pinyon-juniper woodlands.
Abstract:
Severe drought has resulted in widespread tree die-off
events in forests and woodlands globally and is forecast to become more
frequent in coming decades. Tree mortality is a complex process influenced by climate,
soils, characteristics of individual trees, interactions between trees, and the
dynamics of pests and pathogens. The role of stand structure and stand density in
mediating the resistance of trees to drought remains poorly understood,
especially in semiarid woodlands, which are expected to be highly susceptible
to future severe drought. We sampled permanent plots in central Nevada
woodlands dominated by single-leaf pinyon pine and Utah juniper before and
after a severe multi-year drought (2013-2015) to investigate the importance of
climate, tree attributes, and local-neighborhood stand structure on tree
mortality and canopy dieback at the level of individual trees and 0.1-ha plots.

We
observed widespread tree mortality of pinyon at approximately eight times the reported
background mortality rate, and substantial canopy dieback in both pinyon and
juniper. Both species were more prone to mortality and dieback in hotter, drier
sites. Canopy dieback was associated with both long-term average climate and
the severity of recent drought, with elevated mortality on sites with higher
water deficits, average summer temperatures, and vapor pressure deficits. Soils
also played a role in tree dieback, with greater mortality on deeper soils.

While mortality was driven largely
by climate at coarse scales, fine-scale stand structure interacted with climate
to mediate mortality and dieback. Neighborhood statistics showed that trees
were susceptible to competitive influence, and pinyon trees were especially
sensitive to neighborhood density on drier sites. Mortality and dieback were
associated with diverse, co-occurring insect and parasitic plant mortality
agents. Canopy dieback prior to the drought was strongly associated with tree mortality
during the drought, implying that current widespread defoliation caused by
these agents may foreshadow future elevated woodland decline. Fine-scale
influences such as stand structure and soil characteristics play a key role in the
long-term dynamics of semiarid woodlands, and these factors should be
considered in predictive models of forest and woodland susceptibility to drought.

Description of data files:

Raw data (unprocessed):ALL_climate_variables.csv gives climate variables extracted from PRISM or other climate rasters, extracted for each plot.all_vars_EXPORT.csv provides some stand structure and topographic variables for each plot.map_mat_normals.csv gives normal mean annual precipitation and mean annual temperature for each plot, extracted from PRISM 4K rasters downscaled by a 10-m DEMall_trees_with_delta_and_ENN_041916.csv gives individual tree variables including the main response variable (Delta_pdc) and several neighborhood statistics.fdsi_annual_timeseries.csv gives values for FDSI (Williams et al., 2013) for each plot for all years between 1896-2014. ppt_winter_normals.csv gives winter precipitation normals for each plot, extracted from PRISM monthly rasters.soils_missing_imputed_012016.csv gives field-sampled soil texture measurements, with missing values imputed from nearby plots or replaced with SSURGO data, as described in the manuscript.