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Table 1 Predictor variables and expected direction of effect in analyses of annual post-fire establishment, post-fire juvenile stem density, and annual height growth (HG) increment with median and range of plot data. Expected effects (“+” positive, “–” negative, “NT” not tested) were based on prior studies (see superscript numbers and footnotes) in the Blue Mountains ecoregion or neighboring ecoregions

From: Spatial and temporal drivers of post-fire tree establishment and height growth in a managed forest landscape

 

Expected effect by analysis

Predictor variable

Description (units)

Establishment

Density

Annual HG

Median (min.–max.)

Fire

 Distance to seed source

Distance (m) from the plot center to the nearest surviving conspecific conifer with evidence of seed cones (i.e., mature)

NT

a,b

NT

29 (0–260)

 Burn severity

Relative differenced Normalized Burn Ratio (unitless). Larger values indicate higher burn severity

NT

a

+

521 (−41–1167)

Topography

 HLI

Heat load index (unitless) from 0 (coolest) to 1 (warmest)

NT

a,b

0.66 (0.33–0.91)

 Transformed aspect

Beers transformed aspect (unitless) from 0 (warmer, drier aspects) to 2 (cooler, wetter aspects)

NT

+c

+

0.64 (0–1.99)

Climate

 SPEI

Monthly, seasonal, or water year Standardized Precipitation Evaporation Index (unitless). Negative values indicate warmer, drier annual climate conditions, while positive values indicate cooler, wetter conditions

+d

NT

+/–d

NA

Understory

 Grass (%)

Cover of grass (%)

NT

a

NT

11 (0–88)

 Forbs (%)

Cover of forbs (%)

NT

+/–a

NT

18 (0–73)

 Shrubs (%)

Cover of shrubs (%)

NT

+/–a,b

NT

20 (0–65)

Trees

 Juvenile density

Density of post-fire seedlings and saplings (stems ha−a)

NT

NT

4417 (17–100,500)

 Juvenile height

Height of seedlings and saplings (cm)

NT

NT

+

240 (40–470)

Management

 Salvage logged

Salvage logged (22 plots) or not salvage logged (28 plots)

NT

+/–c

NA

  1. a(Boag et al, 2020)
  2. b(Downing et al, 2019)
  3. c(Povak et al 2020)
  4. d(Littlefield 2019)