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Table 5 Predictor variable definitions and associated hypotheses (HA from Table 1) regarding woodborer response to disturbance severity (S), magnitude (M), age (A), and phenology (P), as well as host quality (H) and factors affecting or indicating the potential for larval growth (G) and interspecific competition (C). Values for each predictor variable in this study were drawn from 11 burned or five bark beetle outbreak sites sampled in the greater Sierra Nevada region during the summers of 2015 and 2016. RdNBR = Relative differenced Normalized Burn Ratio, BA = basal area, VRP = variable-radius plot, DOY = day of year, DBH = diameter at breast height, CWHR = California Wildlife Habitat Relationships

From: Patterns of woodboring beetle activity following fires and bark beetle outbreaks in montane forests of California, USA

Predictor Definition and unit of measurement HA
Bark beetle activity Bark beetle sign (present = 1, absent = 0) within a bark sampling quadrata C
Burn severityb RdNBR class (low, moderate, high) at the transect level S
Char depth Bark char depth class (deep = 3, moderate = 2, light = 1, unburned = 0, bark missing = NA) within a bark sampling quadrata S
Char height Mean of two measures of maximum height (m) of char on a treea S
Snag BA ratio Snag BA : total BA (unitless) within a VRP S
Snag BA Dead tree basal area (m2 ha−1) within a VRP M, S
Live tree BA Live tree basal area (m2 ha−1) within a VRP M, S
Needles retained Percent of needles (estimated in 5% increments) retained on a treea A
Fire age Time (yr) since ignition of a burned site A
Bark condition General condition (tight, loose, missing) of bark within a quadrat A
Broken-top tree Top of tree is broken or missing (true, false)a A
Ignition date DOY of site-level ignition and its nonlinear effect (DOY × DOY) P
Host tree taxon Taxon (yellow pine, true fir, or incense-cedar) of a treea H
Tree sizeb Small (13–28 cm DBH = CWHR size class 3) or large (>28 cm DBH = CWHR size classes 4 and 5) G
DBH Diameter (cm) at breast height of a treea G
Height Maximum vertical height (m) of a treea G
Bark aspectb Aspect (northern or southern exposure) of a bark-sampling quadrat G
Elevation Latitude-adjusted plot elevation (m) and its nonlinear effect (m2) G
Latitude, longitude Coordinates of plot position (UTM WGS 84) G
Yearb Sampling year for the site  
Random effectsb Site, transect, plot, and tree  
  1. aFor models of adult woodborer activity, sub-plot data were averaged at the plot level, except bark condition and aspect (not used in adult models) and host tree taxon (replaced by dominant host tree taxon in each plot).
  2. bStudy design variables