Ecological Archives E096-166-A2

Sharon Hood, Anna Sala, Emily K. Heyerdahl, and Marion Boutin. 2015. Low-severity fire increases tree defense against bark beetle attacks. Ecology 96:1556–1565. http://dx.doi.org/10.1890/14-0487.1

Appendix B. Model statistics comparing axial resin duct properties and ring width values between paired resistant and susceptible ponderosa pine trees.

Table B1. F values and significance of models comparing axial duct properties and ring width to the status of paired resistant and susceptible ponderosa pine based on the most recent, common 30 calendar years of tree growth (1981–2010). Susceptible trees were successfully attacked by mountain pine beetle between 2008 and 2011 and killed, while resistant trees survived attack. Models of duct size, duct production, and total duct area include ring area as a covariate. Relative duct area and duct density are standardized to ring area; therefore, ring area is not a covariate in the model.

Effect

Duct size
(mm²)

Duct production
(no. year-1)

Total duct area
(mm² year-1)

Relative duct area
(% annual ring)

Duct density
(no. mm-2 year-1)

Ring width
(mm)

Status

18.25***

1.75

9.83**

4.01*

0.03

2.71

Pair

1.67

1.23

1.62

0.74

0.93

3.69*

Ring Area

29.40***

159.29***

162.33***

NA

NA

NA

F values in bold indicate significance effects at *P ≤ 0.05, ** P ≤ 0.01, and *** P ≤ 0.001. NA = not applicable.

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