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Table 2 Comparison of linear mixed-effects models of ponderosa pine regeneration used for hypothesis testing. Each row represents a unique model. Models inside the shaded area had AAIC values >2 and were not include in model averaging. Seed Dist = distance (m) from plot location to nearest viable seed source. Elev = normalized elevation range of ponderosa pine for each fire: highest elevation = 0 and lowest = 1. TPI = topographic position index normalized for each fire normalized (0 to 1) from ridges (1) to valley bottoms (0). Aspect = deviation from NE (45°) cosine transformation and normalized (0 to 1) aspect for which SW (225°) = 1 and NE = 0. w/Fire = random effects of each fire. K = number of variables (including intercept). AIC = Akaike Information Criterion. ΔAIC = difference in AIC values of other models from “best fit” model.

From: Limits to Ponderosa Pine Regeneration following Large High-Severity Forest Fires in the United States Southwest

Model variables K AIC AAIC
Seed Dist+Elev+Aspect+TPI w/Fire 5 148.30 0.00
Seed Dist+Elev+Aspect w/Fire 4 148.48 0.17
Seed Dist+Elev+TPI w/Fire 4 149.57 1.27
Seed Dist+Elev w/Fire 3 150.08 1.78
Seed Dist+Aspect w/Fire 3 155.33 7.03
Seed Dist+TPI+Aspect w/Fire 4 156.30 8.00
Seed Dist w/Fire 2 158.02 9.72
Seed Dist w/Fire 3 158.94 10.64
Seed Dist 2 162.87 14.57
Intercept w/Fire 1 190.17 41.87
Intercept Only 1 196.59 48.28