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

Ray, Chris; Cluck, Daniel R.; Wilkerson, Robert L.; Siegel, Rodney B.; White, Angela M.; Tarbill, Gina L.; Sawyer, Sarah C.; Howell, Christine A.

doi:10.1186/s42408-019-0040-1

Fire Ecology

Table 5 Predictor variable definitions and associated hypotheses (H_A 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	H_A
Bark beetle activity	Bark beetle sign (present = 1, absent = 0) within a bark sampling quadrat^a	C
Burn severity^b	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 quadrat^a	S
Char height	Mean of two measures of maximum height (m) of char on a tree^a	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 tree^a	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 tree^a	H
Tree size^b	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 tree^a	G
Height	Maximum vertical height (m) of a tree^a	G
Bark aspect^b	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
Year^b	Sampling year for the site
Random effects^b	Site, transect, plot, and tree

^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).
^bStudy design variables

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