Table 2 Descriptions of defense, injury, and biotic stress variables used in logistic regression models predicting tree mortality in the First Order Fire Effects Model (FOFEM) decision support software system, in this study of post-fire tree mortality models from the USA, from fires occurring from 1981 to 2016. These abbreviations are used throughout the paper to refer to these variables

Defense

Bark thickness^ab

BT

Average radial thickness of tree bark

numeric; cm

Diameter at breast height^b

DBH

Diameter of a tree at 1.37 m above the ground

numeric; cm

Injury

Percentage crown volume scorched^ab

CVS

Percentage of tree crown volume scorched or consumed by the fire. Scorched foliage appears brownish red within days after fire. Consumed foliage is partially or completely consumed after fire and remnant foliage and branches are black.

0 to 100

Percentage crown length scorched^b

CLS

Percentage of tree crown length scorched or consumed by the fire. Scorched foliage appears brownish red within days after fire. Consumed foliage is partially or completely consumed after fire and remnant foliage and branches are black.

0 to 100

Percentage crown volume killed^b

CVK

Percentage of tree crown volume for which tree buds (i.e., meristematic tissue that develops into branches, flowers, or foliage; usually at the end of stems), branches, and foliage were killed by fire.

0 to 100

Bark char height^b

BCH

Average vertical height from ground of blackened bark on a tree bole. Char is blackened residue of bark resulting from incomplete combustion and an indicator of the duration that the tree bole was exposed to flames and heat from the fire.

numeric; m

Cambium kill rating^b

CKR

Method used to estimate the amount of cambium killed and stem injury from fire. Requires removing a small sample of bark at four locations at a tree’s base. Cambium kill means the death of the vascular meristematic tissue (i.e., cambium tissue located between bark and secondary xylem) during fire.

0 to 4

Biotic stressors

Beetle presence^b

BTL1

Presence of a bark beetle species that is primary agent of mortality in trees.

0 = absent;

1 = present

Beetle presence^b

BTL2

Presence of a bark beetle species that is primary agent of mortality in trees. This is the same data as for BTL1, but presence and absence is coded differently for use in some predictive models.

−1 = absent;

1 = present

Ambrosia beetle presence^b

AB

Presence of ambrosia beetle

−1 = absent;

1 = present