Ecological Archives E094-201-A2

Margaret R. Metz, J. Morgan Varner, Kerri M. Frangioso, Ross K. Meentemeyer, David M. Rizzo. 2013. Unexpected redwood mortality from synergies between wildfire and an emerging infectious disease. Ecology 94:2152–2159. http://dx.doi.org/10.1890/13-0915.1

Appendix B. Understanding fire-related redwood mortality through model comparisons of fire severity indicators and estimates of fireline intensities for stands in different stages of the disease progression.

Table B1. Comparing alternative† models predicting redwood mortality. Parameter estimates are presented as odds ratios and are bold when they were significant in the models. Model fit and predictability are assessed with the AIC and AUC values.

Predictor

Tree Injury

SOD Presence

SOD Index

Forest Structure

DBH

1.00

1.00

1.00

1.00

% Crown Scorch²

10.11

12.77

10.22

13.16

Soil severity rating

2.12

 

 

 

Bole char height

1.03

 

 

 

SOD presence

 

1.02

 

 

SOD impact index

 

 

3.00 (intermediate)
0.58 (late)

 

Slope

 

 

 

1.01

Aspect (northness)

 

 

 

1.80

Aspect (eastness)

 

 

 

1.93

Basal area (live)

 

 

 

1.00

Basal area (dead)

 

 

 

1.96

Woody debris volume

 

 

 

0.98

AUC
       

    all plots

0.79

0.75

0.78

0.81

infested plots

0.77

0.78

0.79

0.85

uninfested plots

0.79

0.71

0.78

0.77

AIC

70.18

70.69

69.74

76.17

† Standard equations (Hood et al. 2007) use bark thickness and the scorched percent tree crown volume to predict mortality. Applied to our data, these predicted mortality well in uninfested plots (AUC = 0.85) and poorly in infested plots (AUC = 0.62).

 

Table B2. Observed redwood crown scorch heights and calculated (Van Wagner 1973) fireline intensities (FLI) for uninfested and infested coast redwood stands burned in the 2008 Basin fire in Big Sur, CA.

Infestation Stage

Median Scorch Height (m)

Median FLI (kW/m)

Maximum Scorch Height (m)

Maximum FLI (kW/m)

Uninfested/Early

6.5

290

21.0

1680

Intermediate

14.0

920

38.0

4100

Late

7.0

325

13.0

825

 

Literature cited

Hood, S. M., C. W. McHugh, K. C. Ryan, E. Reinhardt, and S. L. Smith. 2007. Evaluation of a post-fire tree mortality model for western USA conifers. International Journal of Wildland Fire 16:679–689.

Van Wagner, C. E. 1973. Height of crown scorch in forest fires. Canadian Journal of Forest Research 3:373–378.


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