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Table 1 Regression models predicting percent tree canopy cover, understory green vegetation cover, total char cover, and total fuel loads (Mg ha−1) measured after the 2007 Egley Fire Complex, eastern Oregon, USA, in 2008 and 2016 as a function of one-year post-fire dNBR, time since treatment (Years), and the interaction of one-year post-fire dNBR and time since treatment. Linear regression models were used for 2008 tree canopy cover, 2008 total char, and 2016 understory green vegetation cover and the degrees of freedom were 66 for all models. Beta regression models were used for 2008 understory green vegetation cover, 2016 tree canopy cover, and 2016 total char cover; number of iterations were 34 + 4 (Fisher scoring), 12 + 2, and 23 + 3, respectively. Generalized linear regressions with Gamma family distributions were used for both 2008 and 2016 total fuel loads. Boldface denotes significance at the 95% confidence interval, and SE denotes standard error of the estimate, t = t-statistic (for linear and generalized linear models), z = Z-statistic (given for beta regression models), E = scientific notation (10 to the power of)

From: Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA

 

Predictor variables

2008

2016

Tree canopy cover (%)

 

Estimate

SE

t

P

Estimate

SE

z

P

dNBR

0.008

0.016

0.491

0.625

−4.66E−03

1.23E−03

–3.782

<0.001

Years

0.245

0.062

3.932

<0.001

7.70E−03

4.01E−03

1.918

0.055

dNBR* Years

–0.001

0.000

–2.944

0.004

−8.90E−06

1.51E−0.5

–0.589

0.556

 

Model: F = 8.6, P < 0.001, R2 = 0.281

Model: z = 6.0, P < 0.001, pseudo R2 = 0.63

Understory green vegetation cover (%)

 

Estimate

SE

z

P

Estimate

SE

t

P

dNBR

–0.005

0.001

–4.187

<0.001

0.048

0.018

2.657

<0.001

Years

–0.007

0.004

–1.731

0.084

–0.034

0.068

–0.491

0.625

dNBR* Years

3.652E-05

0.000

2.376

0.018

–1.81E-04

0.000

–0.806

0.423

 

Model: z = 5.5, P < 0.001, pseudo R2 = 0.44

Model: F = 5.3, P = 0.003, R2 = 0.193

Total char

cover (%)

 

Estimate

SE

t

P

Estimate

SE

z

P

dNBR

0.083

0.023

3.635

<0.001

0.003

0.001

2.849

0.004

Years

0.11

0.087

1.265

0.210

0.004

0.004

0.977

0.328

dNBR* Years

–3.65E-04

0.000

–1.271

0.208

–1.829E-06

0.000

–0.153

0.878

 

Model: F = 12.1, P < 0.001, R2 = 0.356

Model: z = 5.5, P < 0.001, pseudo R2 = 0.26

Total fuel loads (Mg ha–1)

 

Estimate

SE

t

P

Estimate

SE

t

P

dNBR

9.284E-05

0.000

0.618

0.539

3.786E-05

0.000

0.919

0.362

Years

9.186E-06

0.000

0.022

0.982

1.243E-04

0.000

1.022

0.310

dNBR* Years

–1.177E-06

0.000

–0.711

0.480

–8.221E-07

0.000

–1.824

0.073

 

Null deviance: 82.234 on 68 degrees of freedom,

Residual deviance: 79.626 on 65 degrees of freedom

Null deviance: 33.465 on 69 degrees of freedom,

Residual deviance: 27.429 on 66 degrees of freedom