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Table 1 Summary of predictor variables included in statistical models of post-fire regeneration

From: Fire interval and post-fire climate effects on serotinous forest resilience

Variable Definition Mean Median Range
Fire interval Time between stand-replacing fires in years. 16 16 6–31
Pre-fire canopy seed bank Open cones counted on pre-fire standing and fallen trees, measured in variable radius plots, scaled to the hectare and log-transformed (ln[cones ha−1]). 9.08 9.37 5.01–11.75
Depth to bedrock Soil depth to parent material measured in cm. 91 88 69–123
Soil clay content Average percent soil clay within all horizons above depth to bedrock. 17 16 9–26
Post-fire CMD Climatic moisture deficit (CMD), measured in mm as the difference between potential and actual evapotranspiration, calculated by averaging monthly CMD values for the post-fire water year (October 2018 to September 2019). 538 556 350–822
Post-fire relative CMDa Z-score of post-fire CMD relative to the 30-year normal CMD at a site. Negative values represent a cool/wet year relative to the normal period and positive values represent a warm/dry year relative to the normal period. −0.93 −0.99 −1.48 to  −0.02
Shrub cover Percent cover of live shrubs 2 years post-fire, measured in 1 m2 quadrats. 29 29 1–71
Topographic wetness index Index representing potential moisture balance at a site. Low values reflect less potential moisture and high values reflect greater potential moisture. 6.9 6.9 4.4–10.8
Topographic position index Index representing each 30-m cell’s relative neighborhood topographic position. Low values reflect valley bottom positions and high values reflect ridgetop positions. 0.18 0.22 −0.78 to 1.78
Heat load index Index representing the direct incident radiation at a site. Low values reflect low direct incident radiation and high values reflect high direct incident radiation. 0.79 0.80 0.63–0.94
  1. aNot used in final model fitting process — included here for illustrative purposes. Post-fire relative CMD range includes negative values only indicating that the post-fire year was wetter than the 30-year normal period (1981–2010)