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Table 1 Response of fire behavior, weather, and fuel variables to fire season (fixed effects), plot, and year (crossed random effects)

From: Season affects fire behavior in annually burned humid savanna of West Africa

Variables Fixed effects Random effects
Fire season (n = 3) Plot (n = 9) Year (n = 4)
F df P value R2 χ2 (1 df) P value χ2 (1 df) P value
Fire intensitya 7.17 2.33 0.003 0.30 0.00 1.000 2.27 0.132
Flame height 16.17 2.33 < 0.001 0.49 0.01 0.925 1.83 0.176
Rate of fire spreada 11.78 2.33 < 0.001 0.42 0.01 0.912 1.57 0.210
Residence time > 60 °C 4.53 2. 24 0.021 0.27 0.00 1.000 1.34 0.247
Maximum temperature 6.67 2.24 0.005 0.36 0.00 1.000 0.58 0.447
Combustion efficiency 9.24 2.6 0.015   4.49 0.034 0.00 1.000
Wind speed 3.97 2.6 0.029   0.00 1.000 35.59 < 0.001
Air temperature 2.35 2.33 0.112 0.12 0.01 0.921 0.14 0.706
Air humidity 3.55 2.33 0.040 0.18 0.00 1.000 2.83 0.093
Fuel load (fresh) 23.14 2.30 < 0.001   0.00 1.000 10.95 < 0.001
Fuel moisture content 11.16 2.33 < 0.001 0.40 0.00 1.000 0.11 0.738
Grass height 58.41 2.30 < 0.001   0.00 1.000 15.01 < 0.001
  1. Mixed models analyses were performed with the R lmer function. R2 values provided for fixed-effects models when random effects were not significant. Boldface data indicates effects significant at the 0.05 level. F = F value; df = degrees of freedom; χ2 = chi-squared statistic
  2. alog-transformed prior to analysis based on the distribution of residuals.