United States 

Department of 

Agriculture 

Forest Service 

Intermountain 

Region 

Ogden, Utah 

FHP Rpt. R4-01-01 

Evaluation of Tree Survival on 

the Payette National Forest 

1995-1999 
3

Evaluation of Tree Survival. 

on the Payette National Forest 

1995-1999 

by 

Julie C. Weatherby1

R.A. Progar2

Philip J. Mocettini, Jr3

February 2001

Abstract 

Fire is the most important influence on forest vegetation dynamics and 

ecosystem processes in western forests. Ecological and anthropogenic forest 

values are dramatically altered by wildfires. Information on the size, number and 

species of residual trees is essential to interpret fire impacts. Following the 1994 

Payette fires a 100% survey of all living trees greater than 5 inches dbh was 

conducted on established study plots. Annual surveys were conducted 

evaluating dbh, percent crown scorch, percent root and bole char, and cause of 

tree mortality (fire or beetle killed) of Douglas-fir, grand fir, lodgepole pine, 

ponderosa pine, Engelmann spruce, and subalpine fir for the following five years. 

The variables examined had different effects on tree survival according to 

species. Crown scorch was the single most consistent variable associated with 

tree mortality. Mortality related to bole and root char was also significant for most 

of the tree species, however char related mortality incurs destructive sampling 

and is not consistent. Other factors play a significant role in determining tree 

survival following fire and the variables examined should be applied with 

prudence in assessing wildfire impacts. 

 

1 Forest Entomologist (deceased) 

2

 Forest Entomologist, Forest Health Protection, Boise, ID 

3

 Biological Technician, Forest Health Protection, Boise, ID 
4

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its 

programs and activities on the basis of race, color, national origin, gender, 

religion, age, disability, political beliefs, sexual orientation, and marital or family 

status. (Not all prohibited bases apply to all programs.) Persons with disabilities 

who require altenative means for communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s TARGET Center at 202-720-

2600 (voice and TDD) 

To file a complaint of discrimination, write USDA, Director, Office of Civil Right, 

Room 326-W, Whitten Building, 14th and Independence Avenue, SW, 

Washington, DC 20250-9410 or call (202) 720-5964 (voice or TDD). USDA is an 

equal opportunity provider and employer. 
5

Introduction 

Fire is one of the most important mechanism affecting forest vegetation dynamics 

and plays a highly influential role in the ecosystems of the west (Romme and 

Knight 1981, Peet 1988). The ecological and economic impacts of fire are 

important considerations of forest management. Accurate estimates of the 

effects of fire are pertinent to meeting forest resource management objectives in 

some areas. Information on the size, number, and species of trees in a residual 

stand is essential for forest managers and ecologists to interpret the impacts of 

fire on forest stand structure and function. Unfortunately, there are insufficient 

data from which to develop accurate estimates of postfire survival for most 

conifer species in the intermountain region of the western U.S. 

The survival of conifers after fire depends on the type and extent of injury 

(Dieterick 1979, Herman 1954, Wagener 1961, Lynch 1959, Ryan 1982, 

Peterson 1985, Ryan et al. 1988, Reinhardt and Ryan 1988), the initial tree vigor, 

time of the fire in relation to the growing season (Wagener 1961, Dieterick 1979), 

site conditions (Wagener 1961, Dieterick 1979), stand conditions following fire 

that include the influence of insects (Miller and Patterson 1927, Miller and Keen 

1960, Furniss 1965, Dieterick 1979, Fischer 1980), and disease and weather 

(Ryan and Amman 1996). The probability of mortality increases with the degree 

of fire injury and also the severity of each of these external factors. 

Many authors (Peterson 1985, Peterson and Arbaugh 1986;1989, Ryan et al. 

1988) identify the proportion of crown kill as the primary injury contributing to tree 

death, but injury to bole cambium, roots, or both may precede crown injury in 

causing tree mortality (Ryan et al. 1988). Wyant (1986) found that the probability 

of mortality increases with percent crown kill and decreases with increasing bark 

thickness. Mortality resulting from crown kill is often apparent by the end of the 

first growing season following fire, while death from bole and root injury does not 

become apparent before the second growing season (Ryan et al. 1988). On 

average, ponderosa pine trees that have sustained more than 75% crown kill or 

scorch are likely to die (Herman 1954, Salman 1933, Wagener 1961, Weatherby 

et al. 1994). However, Reinhardt and Ryan (1988) report that ponderosa pines 

greater than 20 inches in dbh (diameter at breast height) may tolerate more than 

75% crown scorch. Local data from the Lowman fire (Weatherby et al. 1994) 

support higher estimates of crown scorch for larger trees. Douglas-fir trees 

withstand as much crown scorch as ponderosa pine, however fire damaged trees 

are frequently attacked by Douglas-fir beetles. Data from the Lowman fire of 

1989 indicate that large Douglas-fir over 24 inches dbh were frequently attacked 

by beetles (Weatherby et al. 1994). Smaller Douglas-fir are less likely to be 

attacked and the response to fire should be near that of ponderosa pine. 

Significant tree mortality is frequently associated with bark beetles and 

woodborers following fire. In the absence of significant bole or root injury, the 

likelihood of attack by primary bark beetles is low with light needle kill, increases 
6

with moderate to heavy defoliation and declines with complete needle mortality 

and the concomitant fire kill ( Furniss 1965). 

Objectives 

The objectives of this study were to: 1) determine the levels of crown scorch, 

bole char and root collar char associated with the survival of Douglas-fir 

(Pseudotsuga menziesii), grand fir (Abies grandis), lodgepole pine (Pinus 

contorta), ponderosa pine (Pinus ponderosa), Engelmann spruce (Picea 

engelmannii), and subalpine fir (Abies bifolia) within a 5 year period following the 

Payette fires; 2) determine accurate and practical means to rate tree damage; 

and 3) monitor individual tree survival potential following a fire. 

Methods 

In 1995, study plots were established within the bounds of the 1994 Payette fire 

complex in the French Creek and Pony Creek, Trail Creek and Twenty-mile 

Creek drainages. On plots within these four areas we conducted a 100 percent 

survey of all trees greater than 5 inches that had been damaged by fire but still 

retained green foliage at the time of plot establishment. Tree boles were divided 

into quadrants by bisecting lines running N to S and E to W, intersecting in the 

middle of the tree. Each tree was numbered and an orange dot of paint applied 

at DBH within each quadrant of the tree to aid in relocation. Crown scorch was 

measured to the nearest 10 percent using clear plastic rulers to proportionately 

quantify crown area. Bole char and root collar char (as defined below) were 

evaluated in each tree quadrant. A short increment core was taken from each 

cardinal direction at DBH and as near to ground level as possible. The cambium 

from these cores was inspected and classified as dead or alive by color. Live 

cambium was white, dead cambium was darker than healthy cambium. The 

plots were visited annually during the fire year study period and the condition of 

each tree, either beetle or fire-caused mortality or alive, was recorded. 

Additionally, during the first year of the study 25 trees of each species were 

subsampled (DBH > 10") by coring every 4 inches around the base and 

examining the cambium to classify mortality to validate the quadrant method. 

Definitions: 

Crown Scorch (scorch): The percent of live crown volume killed by a fire. 

Ponderosa pine buds are somewhat fire resistant so it is possible to have 

browning of the foliage without bud kill. Indicators of crown kill include: needles 

dried in an abnormal windswept position and/or no evidence of green on the 

needles, particularly on the fascicle. The best indicator of crownkill is the lack of 

new growth during the season following the fire. 

Bole and root char (char): The percentage of the bole/root circumference killed 

by fire. Fire damage that is sufficient to cause cambial death on aboveground 

portions of the main trunk and in areas extending from the root collar to deeper 

subsurface roots. The intensity of the char and the proportion of the 

circumference of the tree affected are the two aspects needed to accurately rate 
7

bole and root char. When the fissures of thick bark ponderosa pine are no longer 

distinguishable, char is likely intense enough to kill cambial tissue. It is more 

difficult to rate bole char of Douglas-fir because the bark fissures remain even 

though the bole has been severely burned. Spruce, subalpine fir, and lodgepole 

pine possess thin bark and therefore withstand minimal bole or root char. The 

potential for severe root collar and root char is highest on wetter sites where a 

deep duff layer accumulates and a slow burning fire roasts the roots. Wagener 

(1961) and Ryan et al. (1988) note that the most accurate indicator of mortality 

resulting from fire for Douglas-fir is the number of quadrants of cambial kill on the 

bole. Tree death is likely if more than one quadrant is dead at breast height. 

Little fire damage data are available for grand fir, Englemann spruce, lodgepole 

pine or subalpine fir. 

Survival/mortality categories 

Fire-injured beetle killed 

Trees that were placed in the “Beetle” category were killed by beetles as 

indicated by galleries, pitch tubes or boring dust, etc. Trees that were strip 

attacked were not killed and placed in the “Live” category. 

Fire-injured fire killed 

Trees placed in the “Fire” category were dead at the time of the annual survey, 

suffered fire damage and had no signs of beetle activity. 

Fire-injured living 

Fire injured trees that were alive at the time of the annual survey and may have 

been strip attacked by beetles. 

Analyses 

Univariate discriminant analysis (Legendre and Legendre 1998) was used to test 

if the explanatory variables 1) dbh, 2) crown scorch and 3), bole/root char had a 

significant impact on tree survival following wildfire. Testing for differences 

among group means is identical to ANOVA for a single explanatory variable. 

Multiple comparisons were made using a Tukey-Kramer HSD (honest significant 

difference) test (P ≤ 0.05) for each parameter. This test is conservative for 

unequal sample sizes. Nominal logistic regression (SAS 1995) was used to 

estimate the probability of choosing one of the response levels as a function of 

the category of survival. 

Results and Discussion 

During the course of this study the impact of fire on 593 trees over a five-year 

period was evaluated. The majority (254, (43%)) of the trees in the study plots 

were Douglas-fir. Table 1 shows the number (percent) and status of study trees 

by species five years postfire. Table 2 shows the descriptive statistics for the 

variables analyzed for the six tree species studied. Some of the tree species 

evaluated contained too few trees (sample size too small) to accurately evaluate 

fire impacts. 
8

Figure 1. Douglas-fir survivorship five years after wildfire.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5

Years postfire

% 

Trees

Living

Beetle killed

Fire killed

Table 1. Species, number (%) and status of trees evaluated for the impact of wildfire five years after the 

1994 Payette NF fire complex. 

Species Count Live (%) Fire killed(%) Beetle killed (%) 

Douglas-fir (Pseudotsuga menziesii) 254 154 (61%) 33 (13%) 67 (26%) 

Grand fir (Abies grandis) 117 61 (52%) 29 (25%) 27 (23%) 

Lodgepole pine (Pinus contorta) 83 37 (44.5%) 37 (44.5%) 9 (11%) 

Ponderosa pine (Pinus ponderosa) 44 35 (80%) 4 (9%) 5 (11%) 

Engelmann spruce (Picea engenmannii) 44 11 (25%) 26 (59%) 7 (16%) 

Subalpine fir (Abies bifolia) 41 12 (29%) 29 (71%) - 

Douglas-fir 

Sixty-one percent of the Douglas-fir trees were living five years after wildfire, 13% 

of the trees died because of fire and 26% because of Douglas-fir beetle 

(Dendroctonus pseudotsugae). 

Figure 1 shows the cumulative Douglas-fir mortality over the course of the fiveyear study. Mortality directly related to fire was observed by the end of the 

second postfire year, beetle attributed mortality continued for 5 years after fire. 

We could detect no significant (P≤0.05) impact of dbh on the survival of trees as 

a direct result of fire (Figs. 2 & 3). Larger diameter trees have thicker bark and 

are reported to better withstand fire (Martin 1963, Hare 1965), however these 

larger diameter trees also tend to be the preferred host of Douglas-fir bark 

beetles. Weatherby et al (1994) noted that the average dbh of trees surviving the 

Lowman fire of 1989 was 19.33 inches, and those dying from fire and beetles 

were 14.14 and 20.20 inches, respectively. In the Greater Yellowstone fires, 

Amman and Ryan (1991) found that dead trees were not significantly smaller 

than live trees suggesting that root charring near the soil surface may contribute 

to higher than expected mortality. They also noted that insect attack appeared to 

be responsible for part of the additional mortality. Two years following the 

Greater Yellowstone fires of 1988 Amman and Ryan (1991) found that nearly 

70% of the Douglas-fir trees on their plots were infested by beetles. Nominal 

logistic regression (Fig. 4) indicates the probability of a Douglas-fir tree dying 

from fire declines, but beetle mortality increases with increasing tree diameter. 
9

Table 2. Species, status and descriptive statistics of sample trees five years after the 1994 wildfires on the Payette National Forest

Species Parameter Status Mean Count Std. Err. Std. dev. Min. Max. Range 

Douglas-fir DBH Live 15.2 154 0.4 5.3 5.9 28.3 22.4 

 Beetle 22.3 67 0.9 7.1 8.9 40.4 31.5 

 Fire 14 33 0.8 4.6 7.4 24.7 17.3 

 %Scorch Live 11 154 1.8 21.9 0 90 90 

 Beetle 35.7 67 4.1 33.9 0 90 90 

 Fire 49.4 33 6.9 39.8 0 90 90 

 %Char Live 26.1 154 1.7 21.6 0 87.5 87.5 

 Beetle 35.3 67 3.3 27.6 0 87.5 87.5 

 Fire 61.7 33 5.0 28.6 0 100 100 

Grand fir DBH Live 16.9 61 0.7 5.9 5.5 26.6 21.1 

 Beetle 16 27 0.9 4.6 7.6 24 16.4 

 Fire 16.7 29 0.7 5.9 5.5 26.6 21.1 

 %Scorch Live 6.0 61 1.6 12.4 0 80 80 

 Beetle 9.3 27 3.1 16.4 0 60 60 

 Fire 21.0 29 5.3 28.3 0 90 90 

 %Char Live 30.3 61 2.5 19.8 0 75 75 

 Beetle 50 27 3.8 19.9 12.5 87.5 75 

 Fire 73.3 29 4.2 22.8 0.25 100 75 

Lodgepole pine DBH Live 13.7 37 0.4 2.8 7.9 20.7 12.8 

 Beetle 16.0 9 1.23 3.7 11.8 22.2 10.4 

 Fire 13.7 37 0.7 4.1 5.7 23.6 17.9 

 %Scorch Live 1.6 37 0.7 4.4 0 20 20 

 Beetle 16.7 9 9.0 26.9 0 70 70 

 Fire 21.6 37 5.1 31.3 0 90 90 

 %Char Live 34.1 37 3.4 21 0 100 100 

 Beetle 54.1 9 8.3 25.0 12.5 87.5 75 

 Fire 57.4 37 4.2 25.6 12.5 100 87.5 

Ponderosa pine DBH Live 24.5 35 1.4 8.4 9.7 41.8 32.1 

 Beetle 33.9 5 4.6 10.3 18.2 45.8 27.6 

 Fire 20.7 4 8.6 17.3 5.4 41.3 36 

%Scorch Live 11.4 35 3.69 21.84 0 80 80 

 Beetle 22 5 15 3.5 0 80 80 

 Fire 55 4 19.4 38.7 0 90 90 

 %Char Live 14.6 35 3 18 0 75 75 

 Beetle 20 5 15.5 32 0 75 75 

 Fire 65.6 4 17 34.4 25 100 75 

Engelmann spruce DBH Live 11.8 11 1.0 3.3 5.5 17.2 11.7 

 Beetle 10.1 7 1.2 3.3 5.3 15 9.7 

 Fire 12.0 26 0.8 4.1 6 21.7 15.7 

%Scorch Live 4.5 11 2.5 8.2 0 20 20 

 Beetle 0 7 0 0 0 0 0 

 Fire 0.5 26 0.05 13.9 37.5 75 37.5 

%Char Live 36.3 11 7.2 24.0 0 87.5 87.5 

 Beetle 53.6 7 5.2 13.9 37.5 75 37.5 

 Fire 69.2 26 5.1 26.0 12.5 100 87.5 

Subalpine fir DBH Live 7.9 12 0.4 1.6 5.4 10.5 5.1 

 Fire 9.4 29 0.5 2.9 5.3 16 10.7 

 %Scorch Live 7.5 12 2.8 9.6 0 30 30 

 Fire 42.7 29 6.3 33.8 0 100 100 

 %Char Live 26 12 4.2 14.5 0 50 50 

 Fire 62 29 5.2 28.0 12.5 100 87.5 
10

0

0.25

0.5

0.75

1

5 10 15 20 25 30 35 40

DBH

Beetle

Fire

Living

However, the probability of beetle attack increased with dbh (Fig. 4). The 

probability of occurrence (Y) at a specified X-value is the distance from the Xaxis to the first curved line for beetle caused mortality, between the two sigmoid 

lines for fire caused mortality, and from the upper sigmoid line to the top of the 

figure for surviving trees. For example at a dbh of 15 there was approx. a 16% 

5

10

15

20

25

30

35

40

Beetle Fire Living

Tree status

All Pairs

Tukey-Kramer

 0.05

Figure 4. Nominal logistic regression plot of 

Douglas-fir dbh by tree survival category. 

Probability of occurrence is on the Y-axis, dbh 

(inches) is on the X-axis.

Figure 2. Comparison of Douglas-fir dbh among survival categories shows that tree diameter 

was significantly higher among trees killed by beetles. (Circles that overlap indicate nonsignificant differences (P ≤ 0.05) among means in the diagram to the right). 

Figure 3. Average dbh ±2SE for each 

survival category of Douglas-fir.

0.0

2.9

5.8

8.7

11.6

14.4

17.3

20.2

23.1

26.0

DF_live DF_fire DF_beetl

Douglas-fir survivorship five years after fire

DBH (inches)

R-sq = 0.14 

Chi-sq = 64.36 

P > Chi-sq < 0.0001 

F = 39.45 

Df = 2, 251 

P > F < 0.0001 
11

probability of the tree dying from beetle attack, 13% from fire related causes and 

61% of surviving after five years. Discriminant analysis (Fig. 2) indicates that 

beetles cause significant mortality of fire-injured trees. Large trees that survived 

fire were in a weakened condition and more susceptible to attack by beetles. In 

some burned over forests, trees that are likely to be attacked by bark beetles 

would normally recover from fire damage (Miller and Patterson 1927, Furniss 

1965). Furniss (1965) reported that the incidence of Douglas-fir beetle attacks 

increased with the degree of crown and cambial injury, but abruptly declined in 

completely defoliated trees. Beetle brood survival is reduced in fire-damaged 

stands, when compared to unburned areas because of pitch invasion and sour 

sap (Miller and Patterson 1927, Furniss 1965). There is some contradiction in 

the literature regarding the capacity of beetle populations to build in fire injured 

trees to levels that may overcome the defenses of uninjured green trees. Some 

authors note that most fires do not contribute to large bark beetle outbreaks 

(Miller and Keen 1960, Furniss 1965). Elevated levels of beetle caused mortality 

have been observed within a 2-3 year period following fire but were confined to 

damaged trees (Miller and Patterson 1927). Other authors have found that 

populations have increased in the fire-injured trees and spread to uninjured trees 

(Bedard 1950, Amman and Ryan 1991, Pasek 1991). Our data indicate that 

beetle attacks were still occurring in our plots 5 years after fire (Fig. 1). 

Crown scorch has been considered a primary factor in causing fire-attributed tree 

mortality. In this study, the average crown scorch of surviving Douglas-fir five 

years postfire was 11%, those killed directly by fire or subsequently by beetles 

experienced 49.4% and 35.7% crown scorch, respectively. Figure 5 shows that 

crown scorch ranged from 0-90% for all three categories of tree survival. There 

were few beetle attacks of trees that received more than 60% crown scorch. 

Figure 6 shows the distribution of the means among the tree survival categories. 

We found no significant difference in the amount of crown scorch between beetle 

and fire killed trees, however those trees living after five years had significantly 

less crown scorch than fire/beetle killed trees (Figs. 5 & 6). 

-10

0

10

20

30

40

50

60

70

80

90

100

Beetle Fire Living

Tree status

All Pairs

Tukey-Kramer

 0.05

Figure 5. Comparison of % 

crown scorch among 

Douglas-fir survival 

categories shows that 

scorch has a significant 

impact on tree survival. 

Trees in the living category 

had significantly less 

scorch than beetle or fire 

killed trees (P ≤0.05). 

F = 35.14 

Df = 2, 251 

P > F < 0.0001 
12

Figure 8. Comparison of 

percent char of Douglasfir show significant 

greater char of fire killed 

trees (non-overlap 

among the circles at 

right indicates 

significance (P ≤ 0.05)). 

Weatherby et al. (1994) found that 

the average crown scorch of 

Douglas-fir trees surviving the 1989 

Lowman fire was 20%, and those killed by fire and beetle attack 74% and 39%, 

respectively. Ryan et al. (1988) found that the average crown scorch was 39% 

for dead trees. They also noted that percent crown scorch varied considerably, 

0-80% for living trees and 0-100% for dead trees. Ryan et al. (1996) found that 

beetles preferred trees with less than 75% crown scorch. Although scorch is an 

easily measured parameter in assessing fire related tree survival, other less 

discrete factors exert considerable influence over the probability of tree mortality. 

Bole and root char also exerted a significant impact on survival of Douglas-fir 

(Figs. 7 & 8). The average char sustained by trees surviving fire was 26.1% and 

ranged from 0-87.5%. Our data correspond to studies by Wagener (1961) and 

Ryan et al. (1988) who stated that trees sustaining cambial fire damage of more 

than a single quadrant were unlikely to survive. The average char sustained by 

beetle killed trees was 35.3% (range 0-87.5%) and by fire-killed trees 73.3% 

(range 0-100%). Ryan et al. (1996) noted that Douglas-fir beetle preferred trees 

0.0

11.1

22.2

33.3

44.4

55.6

66.7

77.8

88.9

100.0

DF_live DF_fire DF_beetl

Douglas-fir survivorship five years after fire

% scorch

0

0.25

0.5

0.75

1

-10 0 10 20 30 40 50 60 70 80 90 100

Crown Scorch

Beetle

Fire

Living

Figure 7. Plot of nominal logistic regression of 

Douglas-fir crown scorch by survival category 

shows that the probability of survival decreases 

with increasing scorch (top series). 

Figure 6. Average Douglas-fir % scorch 

±2SE for each survival category. 

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

F = 29.51 

Df = 2, 251 

P > F < 0.0001 
13

Figure 10. Plot of nominal logistic 

regression of Douglas-fir bole/root char by 

survival category shows that the probability 

of survival decreases with increasing char 

(top series).

with more than 50% basal girdling. We did not find a strong relationship between 

char and beetle attack (Fig. 10). Our data suggests a relationship of 

increasing/declining beetle attack corresponding to increasing bole char as 

described by Furniss (1965). 

In 

1994, Weatherby et al. found that the model 

developed by Reinhardt and Ryan (1988) 

based on bark thickness and percent crown 

scorch accurately classified trees as alive or dead following fire 83% of the time. 

Applying the current data set to the model indicated that 6% (9) of the trees that 

survived were predicted to die. An additional 71 trees (28% of total) that died 

were expected to survive the fire based on the model. Of these, 56 (22% of total) 

were killed by bark beetles and 15 (6% of total) by fire. Those trees killed by 

beetles after the fire represent a large portion (22%) of the misclassification. 

Grand fir 

Five years after wildfire, 52% of the 117 grand fir trees in our study were living, 

25% were killed by fire and 23% were killed by bark beetles (Scolytus ventralis). 

Figure 11 shows the cumulative mortality of grand fir over the course of the fiveyear study. Beetle attributed mortality was as severe as direct fire-related tree 

death. 

Table 2 shows the descriptive statistics for the three conditions of mortality 

evaluated in this study. Univariate discriminate analysis showed no significant (P 

≤ 0.05) impact of dbh on grand fir survival (Fig. 12).

0.0

0.1

0.2

0.3

0.4

0.6

0.7

0.8

0.9

1.0

DF_Live DF_fire DF_beetl

Douglas-fir survivorship five years after fire

% char

0

0.25

0.5

0.75

1

-0.1 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0

Char

Beetle

Fire

Living

Figure 9. Average % char ±2SE of 

Douglas-fir for each survival category. R-sq = 0.10 

Chi-sq = 48.29 

P < Chi-sq < 0.0001 
14

Figure 11. Grand fir survivorship five years after fire.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

12345

Years post-fire

%Trees

Living

Beetle killed

Fire killed

There has been little fire related research conducted in grand fir stands, however, 

the morphological characteristics of grand fir are similar to those of white fir 

(Abies concolor) which has moderate fire resistance with fire resistance 

increasing with increasing age (Flanaghan 1996). Burns and Honkala (1990) 

note that grand fir fire resistance may be based largely on habitat. On moister 

sites it is easily killed by ground fires. On drier sites, deeper root systems and 

thicker bark increase resistance to fire. We found that dbh had no observable 

effect on the susceptibility of grand fir to fire related mortality (Fig. 12). 

Figure 12. Comparison of 

dbh among grand fir 

survival categories shows 

no significant differences 

among tree survival 

categories. (Overlapping 

circles in the figure at right 

indicate non-significant 

differences (P ≤ 0.05)). 

5

10

15

20

25

30

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

F = 0.28 

Df = 2, 114 

P > F < 0.75 
15

-10

0

10

20

30

40

50

60

70

80

90

100

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Crown scorch (Figs 13 & 14) averaged 6% (range 0-80%) in those trees 

surviving fire, 9.3% (range 0-60%) in trees attacked and killed by beetles and 

21% (range 0-90%) in those trees killed directly by fire. The relatively weak 

relationship of crown scorch in grand fir to tree mortality is shown in figure 15. 

Note the association of scorch with beetle attack is minimal as indicated by the 

near horizontal aspect of the lower series corresponding to beetle mortality. 

Figure 13. Comparisons 

of grand fir crown scorch 

show significantly lower 

scorch in living trees than 

those killed by fire. 

(Overlapping circles in 

the figure at right indicate 

non-significant 

differences (P ≤ 0.05)). 

Figure 14. Average % crown scorch ±2SE for 

each grand fir survival category. 

0

0.25

0.5

0.75

1

-10 10 30 50 70 90

% Crown Scorch

Beetle

Fire

Living

Figure 15. Plot of nominal logistic regression of grand 

fir crown scorch among survival categories shows 

that the probability of survival decreases with 

increasing scorch (top series). 

F = 6.56 

Df = 2, 114 

P > F < 0.002

R-sq = 0.05 

Chi-sq = 11.01 

P > Chi-sq 

<0.004 
16

Grand fir bole and root char, unlike crown scorch, showed a strong relationship 

with tree survival. Figure 16 indicates bole and root char significantly increased 

grand fir mortality and influenced susceptibility to beetle attack. The variability of 

char among survival categories (figs. 16 & 17) was lower than values observed 

for dbh or scorch, indicating that char is an improved parameter for evaluating 

fire related mortality of grand fir over dbh or crown scorch. Figure 18 shows the 

strong relationship of char with tree survival. The relationship of char with beetle 

attack is shown in the lower series. 

Figure 16. Comparison of 

grand fir bole/root char shows 

significant differences between 

the three survival categories. 

(Non- overlapping circles in the 

figure at right indicate 

significant differences among 

the groups (P ≤ 0.05)). 

0.0

0.1

0.2

0.3

0.4

0.6

0.7

0.8

0.9

1.0

GF_live GF_fire GF_beetl

Grand fir survivorship five years after fire

% char

Figure 17. Average % bole/root char ±2SE 

for each grand fir survival category. 

0

0.25

0.5

0.75

1

-0.1 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0

Bole/Root

Beetle

Fire

Living

R-sq = 0.26 

Chi-sq = 61.36 

P > Chi-sq < 0.0001 

Figure 18. Plot of nominal logistic 

regression of grand fir bole/root char 

among survival categories shows that the 

probability of survival decreases with 

increasing char (top series). 

F = 43.44 

Df = 2, 116 

P > F < 0.0001 

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

F = 43.44 

Df = 2,116 

P > F < 0.0001 
17

The hump-shaped distribution (Fig. 18) of the lower series corresponding to 

beetle mortality is stronger than the response observed in Douglas-fir. The 

probability of beetle attack increases with % char and exhibits a corresponding 

decline at higher percentages of char. The middle series indicates that char 

related mortality occurs above 25% and increases dramatically above 50%. 

Lodgepole pine

There were 83 lodgepole pine trees sampled in our study. Lodgepole is 

considered to have low resistance to fire because of its thin bark (Flanagan 

1996). The cycle of lodgepole stand replacement by beetle caused mortality, 

followed by fire and regeneration from serotinous cones has been well 

established (Stuart et al. 1989). In this study, 44.5% (37) of the trees were living 

five years after fire, 44.5% (37) were killed as a result of fire and 11% (9) were 

killed by mountain pine beetles (MPB) (Dendroctonus ponderosae). Figure 20 

shows the cumulative mortality of trees over the course of the five-year study. 

Ryan and Amman (1996) found in their study that 61% of 151 lodgepole pines 

were attacked and killed by insects. 

Mountain pine beetle is not strongly attracted to fire-damaged lodgepole pine 

(Amman and Ryan 1991, Ryan and Amman 1996). It was suggested that most 

of the trees killed by insects were more than 75% girdled by fire and primarily 

infested by pine engraver (Ips spp.) (Amman and Ryan 1991, Ryan and Amman 

1996). 

Figure 19. Cumulative lodgepole pine survivorship five years after fire.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

12345

Years post-fire

%Trees

Living

Beetle killed

Fire killed
18

The average dbh of trees surviving fire was 13.7 inches. Those trees killed by 

fire had an average dbh of 13.7 inches and those killed by beetles were 16 

inches in diameter. Figure 20 shows the average dbh did not significantly differ 

among tree survival categories. We found no relationship between the diameter 

of lodgepole pine and tree survival. 

 

As expected, crown scorch was significantly higher (P ≤ 0.05) in fire-killed trees 

than in trees living after five years (Figure 21). 

5

10

15

20

25

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

F = 1.76 

Df = 2, 80 

P > F < 0.17 Figure 20. Comparison of 

lodgepole pine dbh shows 

no significant differences 

between the three survival 

categories. (Nonoverlapping circles in the 

figure at right indicate 

significant differences 

among the groups (P ≤

0.05)). 

-10

0

10

20

30

40

50

60

70

80

90

100

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Figure 21. 

Comparison of crown 

scorch of lodgepole 

pine shows fire killed 

trees had significantly 

higher scorch than 

living trees. (Nonoverlapping circles in 

the figure at right 

indicate significant 

differences among the 

groups (P ≤ 0.05)). 

F = 7.27 

Df = 2, 80 

P > F < 0.001 
19

0

0.25

0.5

0.75

1

-10 10 30 50 70 90

Crown Scorch

Beetle

Fire

Living

We found lodgepole pine to be extremely intolerant of crown scorch, exhibiting a 

sharp decline in survival with increasing scorch (Fig 22). Our data correspond to 

the findings of Ryan and Amman (1996) who noted that surviving trees sustained 

less than 25% crown scorch. 

Root and bole char also had a significant (P ≤ 0.05) impact on lodgepole survival 

(Fig. 23). As would be expected, living trees exhibited significantly less bole and 

root char than those killed by fire. 

Figure 24 indicates that in our study char had a marginal effect on beetle attack 

as shown by the lower series, however char strongly affected tree survival as 

shown in the upper two series. 

Figure 22. Plot of nominal 

logistic regression of 

lodgepole pine crown 

scorch among survival 

categories shows that the 

probability of survival 

dramatically decreases 

above 25% scorch (top 

series). Probability of 

occurrence is on the Yaxis, degree of scorch is 

on the X-axis. 

R-sq = 0.12 

Chi-sq = 19.77 

P > Chi-sq < 0.0001 

F = 9.56 

Df = 2, 80 

P > F < 0.0002 

Figure 23. Comparison of 

bole and root char of 

lodgepole pine shows fire 

killed trees had 

significantly higher char 

than living trees. (Nonoverlapping circles in the 

figure at right indicate 

significant differences 

among the groups (P ≤

0.05)). 

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

F = 9.56 

Df = 2, 80 

P > F < 0.0002
20

Ryan and Amman (1996) found that the average basal girdling of living trees was 

56%. We found bole/root char girdled an average of 34% of the trunk in living 

trees and 57% in trees killed by fire. 

Ponderosa pine 

Fire impacts were evaluated on 44 ponderosa pine trees. Five years after 

wildfire, 80% (35) were living, 9% (4) were killed by fire and 11% (5) by bark 

beetles (Dendroctonous brevicomis). Figure 25 shows the cumulative mortality 

of ponderosa pine during the five-year study. Ponderosa pine exhibited the 

highest percent survival rate of all tree species in our study. The primary cause 

of fire-induced mortality in ponderosa pine is crown scorch (Dieterich 1979). 

Mann and Gunter (1960) state that cambial injury is significant when all four 

quadrants are injured in a tree with greater than 50% crown scorch. Wagener 

(1961) stated that fire has a greater impact on tree survival when occurring early 

in the season. The Payette fire complex occurred late in the season from July 

through September 1994. Wagner (1961) noted that trees may survive complete 

crown scorch if fully formed buds and twigs were not extensively damaged. 

0

0.25

0.5

0.75

1

-0.1 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0

Bole/Root

Beetle

Fire

Living Figure 24. Plot of 

nominal logistic 

regression of lodgepole 

pine bole and root char 

among survival 

categories shows a 

nearly linear relationship 

of mortality increasing 

with increasing char 

(middle series). 

Probability of occurrence 

is on the Y-axis, degree 

of char is on the X-axis.

R-sq = 0.11 

Chi-sq = 17.87 

P > Chi-sq <0.0001 

Figure 25. Ponderosa pine survival five years after fire.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

12345

Years post-fire

%Trees

Living

Beetle killed

Fire killed
21

0

0.25

0.5

0.75

1

5 10 15 20 25 30 35 40 45 50

DBH

Beetle

Fire

Living

The average dbh of ponderosa pine surviving fire was 24.5 inches, those killed 

directly by fire were 20.7 inches and trees killed by beetles 34 inches (Table 2, 

Fig 26). The lack of significant differences in dbh among the categories of 

survival may be attributed to the small sample size. Figure 27 indicates a sharp 

decline in fire related mortality may occur with increasing dbh. 

 

 

Significant differences (P ≤ 0.05) in the average percent of crown scorch were 

found between trees killed by fire and those surviving (Fig. 28). Fire killed 

ponderosa pine had an average crown scorch of 55%, those killed by beetles 

had 22% and those surviving wildfire had an average scorch of 11% (Table 2). 

These values are comparable to the percent scorch in fire-killed and surviving 

Douglas-fir. As noted earlier, Douglas-fir and ponderosa pine may exhibit similar 

5

10

15

20

25

30

35

40

45

50

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Figure 26. Comparison 

of dbh of ponderosa 

pine among categories 

of survival shows no 

significant difference. 

(Overlapping circles in 

the figure at right 

indicate non-significant 

differences among the 

groups (P ≤ 0.05)). 

R-sq = 0.09 

Chi-sq = 5.38 

P > Chi-sq < 0.07 

Figure 27. Nominal logistic 

regression of ponderosa pine 

dbh among survival categories 

indicate a sharp decline in 

mortality may occur with 

increasing dbh. Probability of 

occurrence is on the Y-axis, dbh 

is on the X-axis. 

F = 2.6 

Df = 2, 41 

P > F < 0.08 
22

0

0.25

0.5

0.75

1

-10 10 30 50 70 90

Crown Scorch

Beetle

Fire

Living

resistance to fire. Burns and Honkala (1990) note that survival is higher if less 

than 50% of the crown is scorched. Weatherby et al. (1994) showed that few 

ponderosa pines greater than 4 inches dbh were killed by fire if crown scorch 

was less than 80%. 

 

Figure 29 shows the probability of survival declining above 50% crown scorch. 

As expected, trees surviving wildfire exhibited significantly less (P ≤ 0.05) 

bole/root char than those killed by fire (Fig. 30). The average char of surviving 

ponderosa pine was 14.6%, trees killed by fire averaged 65% char and those 

killed by beetles averaged 20% char. It is emphasized that the small sample size 

does not represent all ponderosa pine, other studies (Weatherby et al. 1994, 

Ryan and Amman 1996) indicated a higher fire tolerance of ponderosa pine than 

shown in this study. 

-10

0

10

20

30

40

50

60

70

80

90

100

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Figure 28. Comparison 

of crown scorch of 

ponderosa pine show 

significant differences 

between those surviving 

and those killed by fire. 

(Overlapping circles in 

the figure at right 

indicate non-significant 

differences among the 

groups (P ≤ 0.05)). 

F = 5.67 

Df = 2, 41 

P > F < 0.006 

Figure 29. Plot of nominal logistic 

regression of ponderosa pine 

crown scorch among survival 

categories indicate the probability 

of mortality rapidly increasing 

above 50% scorch. Probability of 

occurrence is on the Y-axis, 

degree of scorch is on the X-axis. 

R-sq = 0.13 

Chi-sq = 7.67 

P > Chi-sq < 0.02 
23

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Beetle

Fire

Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Engelmann spruce 

There were forty-four Engelmann spruce trees in our study. Five years following 

wildfire, 25% were living, 59% were killed by fire and 16% were killed by spruce 

beetle (Dendroctonous rufipennis) (Table 1). Figure 31 shows the cumulative 

impacts of fire on trees in the plots over course of the five-year study. Fewer fireeffects studies have been done in Engelmann spruce stands than most other 

species. Amman and Ryan (1991) found that 83% of the 17 trees in their study 

were killed by fire or beetles. Rasmussen et al. (1996) found 31.9% of 439 

Engelmann spruce trees in the Greater Yellowstone fires were killed by fire 

related injury and 6.6% by insects (half of these were spruce beetle). 

Our data support the conclusions of Ryan and Amman (1994) who noted that 

mortality did not vary with tree diameter. Diameter at breast height did not affect 

tree survival as shown in Figure 32. The average dbh of surviving spruce trees 

Figure 30. Comparison of 

bole/root char of ponderosa 

pine show significantly 

higher char in fire-killed 

trees. (Overlapping circles in 

the figure at right indicate 

non-significant differences 

among the groups (P ≤

0.05)). 

F = 10.29 

Df = 2, 41 

P > F < 0.0002 

Figure 31. Engelmann spruce survivorship five years after fire. 

0

5

10

15

20

25

30

35

40

45

12345

Years post-fire

# Trees

Living

Beetle killed

Fire killed
24

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

in our study was 11.8 inches, those killed by beetles were 10.1 inches and trees 

killed by fire averaged 12.0 inches. 

 

There was little crown scorch observed among the spruce trees in this study. 

Four trees had 10% crown scorch, 2 trees had 20% and 1 tree had 70%. 

 

\ 

Bole and root char were the primary impacts of fire on spruce trees. Trees 

surviving fire had significantly less char than those killed by fire (Fig. 33). The 

average bole/root char of Engelmann spruce surviving fire was 36.3%, those 

trees killed by beetles had 53.6% char, and fire-killed trees had 69.2 % char. 

Since spruce is a thin barked species and sensitive to fire, the probability of char 

related mortality showed a sharp increase with increasing char (Fig. 34). At 50% 

char the probability of mortality is greater than 50%. 

5

10

15

20

Beetle Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Figure 32. Comparison of 

dbh of Engelmann spruce 

shows no significant effect 

on tree survival. 

(Overlapping circles in the 

figure at right indicate nonsignificant differences 

among groups (P ≤ 0.05)). 

F = 0.7 

Df = 2, 41 

P > F < 0.49 

Figure 33. Comparison of 

bole/root char of Engelmann 

spruce among shows 

significant differences 

between those surviving and 

those killed by fire. 

(Overlapping circles in the 

figure at right indicate nonsignificant differences among 

the groups (P ≤ 0.05)). 

F = 7.34 

Df = 2,41 

P > F < 0.002 
25

Figure 34. Plot of 

nominal logistic 

regression of Engelmann 

spruce bole/root char 

among survival groups. 

Probability of occurrence 

is on the Y-axis, degree 

of char is on the X-axis. 

0

0.25

0.5

0.75

1

-0.2 .2 .4 .6 .8 1.0 1.2

Bole/Root

Beetle

Fire

Living

Subalpine fir

Subalpine fir are noted for their lack of fire resistance because of their thin bark 

(Ryan and Amman 1994). Fire vigorous enough to scorch the bark will kill the 

cambium. Twenty-nine percent of the subalpine fir were alive following fire in this 

study (Table 1). Most of the fire caused mortality had occurred by the third year 

(Figure 35). Rasmussen et al. (1996) stated that 37.3% of 134 subalpine fir 

survived fire in their study. Fifty percent of the mortality was attributed to fire 

injury and 7.5% to insects. All 17 of the subalpine fir in the study by Ryan and 

Amman (1994) were killed by fire that girdled over 80% of the tree bole. 

R-sq = 0.16 

Chi-sq = 13.35 

P > Chi-sq = 0.001 

Figure 35. Alpine fir survival five years after fire. 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

12345

Years post-fire

%Trees

Living

Fire killed
26

We found no significant differences in dbh between fire killed and surviving trees 

(Fig. 36). Beetle attack of subalpine fir was not observed. Trees killed by fire 

averaged 9.4 inches dbh, and those surviving were 7.9 inches in diameter. 

4

6

8

10

12

14

16

18

Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Crown scorch was significantly higher in trees killed by fire (42.7%) than those 

living (7.5%) five years later (Fig. 37). 

-10

0

10

20

30

40

50

60

70

80

90

100

Fire Living

INDIDS 99

Each Pair

Student's t

 0.05

Figure 36. Comparison 

of dbh of subalpine fir 

shows no significant 

effect. (Overlapping 

circles in the figure at 

right indicate nonsignificant differences 

between groups (P ≤

0.05)). 

t = 1.63 

Df = 1, 39 

P > t < 0.11

Figure 37. Comparison of 

crown scorch of subalpine 

fir show significantly higher 

scorch in trees killed by 

fire. (Non-overlapping 

circles in the figure at right 

indicate significant 

differences between 

groups(P ≤ 0.05)). 

t = 3.52 

Df = 1, 39 

P > t = 0.001 
27

Figure 38 shows the relationship between percent crown scorch and probability 

of survival. Note the sharp increase in the probability of mortality with increasing 

crown scorch. 

0

0.25

0.5

0.75

1

-10 10 30 50 70 90

Crown Scorch

Fire

Living

Subalpine fir was also sensitive to bole and root char. The average char of trees 

surviving fire was 26% and the mean of trees killed by fire 62%. Figure 39 

indicates that % char was significantly less in surviving trees. 

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Fire Living

INDIDS 99

All Pairs

Tukey-Kramer

 0.05

Figure 38. Plot of nominal 

logistic regression of 

subalpine fir crown scorch 

between living and fire-killed 

trees shows the probability of 

mortality rapidly increasing 

with increasing scorch. 

Probability of occurrence is 

on the Y-axis, degree of 

scorch is on the X-axis. 

R-sq = 0.27 

Chi –sq = 13.67 

P > Chi-sq = 0.0002 

Figure 39. Comparison of 

bole/root char of subalpine 

fir between categories of 

mortality shows 

significantly higher char in 

trees killed by fire. (Nonoverlapping circles in the 

figure at right indicate 

significant differences 

between group (P ≤ 0.05)).

t = 4.2 

Df = 1, 39 

P > t = 0.0001 
28

Figure 40 shows the lack of tolerance of bole and root char of subalpine fir. Note 

the sharp rise in the probability of mortality above values of 30%. 

0

0.25

0.5

0.75

1

-0.2 .2 .4 .6 .8 1.0 1.2

Bole/Root

Fire

Living

Conclusions 

The impact of wildfire varied with the parameter examined among tree species. 

Although dbh, crown scorch, and bole and root char are measurable and are 

shown to significantly influence tree survival following wildfire, the influence of 

initial tree vigor, site and stand conditions, season of the fire, and factors in 

combination impact tree survival. Within species, different levels of tree survival 

were sustained at similar degrees of variable impact in the Lowman fires and the 

Greater Yellowstone fires when compared to the Payette fires of 1994. 

The variables evaluated to assess the impact of fire on tree survival/mortality in 

this study were the most evident and easiest to obtain. Rating of bole and root 

char in particular is difficult because it requires destructive sampling and it is 

difficult to assess cambial death. Models combining dbh and crown scorch are 

good predictors of tree survival when bark thickness is related to tree diameter as 

observed in the thick-barked trees, and bark beetle induced mortality is negligible 

or is not relevant. However, dbh in thin-barked species had no impact on tree 

survival. Thick-barked species (ponderosa pine and Douglas-fir) had a much 

higher survival rate than the thin-barked species (subalpine fir, Engelmann 

spruce and lodgepole pine). Crown scorch was the single most relevant variable 

in assessing tree survival, however, the impact of crown scorch on tree survival 

varied widely within and among tree species. 

The role of external unmeasured variables significantly influences tree mortality. 

Figure 40. Plot of nominal 

logistic regression of 

subalpine fir bole/root char 

between living and firekilled trees shows the 

probability of mortality 

rapidly increasing with 

increasing scorch. 

Probability of occurrence is 

on the Y-axis, degree of 

scorch is on the X-axis. 

R-sq = 0.33 

Chi-sq = 16.37 

P > Chi-sq < 0.0001 
29

A significant factor causing tree mortality as an indirect result of fire was the 

propensity of beetle attack. Since most tree species are more susceptible to 

beetles as a result of wildfire, it is difficult to predict the impact of fire on tree 

mortality. Bark beetles were responsible for the majority of Douglas-fir mortality. 

Crown scorch and bole char are the most accurate parameters related to post 

wildfire tree survival, but need to be applied with the foreknowledge that they are 

associated with considerable variability and should be applied with caution. 
30

Literature Cited 

Amman, G.D. and K.C. Ryan. 1991. Insect infestation of fire-injured trees in 

Greater Yellowstone area. USDA Forest Service, INT Research Station. 

Research. Note INT-398. 9pp. 

Bedard, W.D. 1950. The Douglas-fir beetle. USDA Cir. 817. 10 pp. 

Burns, R.M. and B.H. Honkala. 1990. Silvics of North America, Volume 1, 

Conifers. Washington, D.C.: Agriculture Handbook 654. USDA Forest Service, 

673p. 

Dieterick, J.H. 1979. Recovery potential fire-damaged southwestern ponderosa 

pine. USDA Forest Service, Rocky Mountain Forest and Range Experiment 

Station, CSU, Fort Collins, CO, Res. Note RM-379,b 8 pp. 

Fischer, W.C. 1980. Prescribed fire and bark beetle attacks in ponderosa pine 

forests. USDA Forest Service, Fire Management Notes. Pp. 10-12. 

Flanagan, P. 1996. Survival of fire-injured conifers. Fire Management Notes 

56:13-16. 

Furniss, M.M. 1965. Susceptibility of fire-injured Douglas-fir to bark beetle attack 

In southern Idaho. Journal of Forestry 63: 8-11. 

Gibson, K.E. and B. Ping. 1999. Bark beetle outbreaks following the Little Wolf 

Fire, Tally Lake Ranger District, Flathead National Forest. USDA Forest Service, 

North Region, FHP Rep. # 99-7. 15pp. 

Hare, R.C. 1965. Contribution of bark to fire resistance of southern trees. Journal 

of Forestry 63: 248-251. 

Herman, F.R. 1954. A guide for marking fire-damaged ponderosa pine in the 

southwest. USDA Forest Service, Rocky Mountain Forest and Range 

Experimental Station. Research Notes RM-13, 4pp. 

Legendre, P, and L. Legendre. 1998. Numerical Ecology. Elsevier, New York, 

New York. pp. 616-633. 

Lynch, D.W. 1959. Effects of a wildfire on mortality and growth of young 

ponderosa pine trees. USDA Forest Service, Intermountain Forest and Range 

Experimental Station, Ogden, UT. Res. Note INT-66. 8 pp. 

Mann, W.F. and E.R. Gunter. 1960. Predicting the fate of fire-damaged pines. 

Forest and People 10: 26-27. 
31

Martin, R.E. 1963. A basic approach to fire injury of tree stems. In: Proceedings, 

1963 Tall Timbers Fire Ecology Conference 2: 151-162. 

Miller, J.M. and F.P. Keen. 1960, Biology and control of the western pine beetle. 

USDA Forest Service, Wash. D.C. Misc. Pub. #800, 381 pp. 

Miller, J.M. and J.E. Patterson. 1927. Preliminary studies on the relation of fire 

injury to bark beetle attack in western yellow pine. Journal of Agriculture 

Research 34: 597-613. 

Pasek, J.E. 1991. Population of Douglas-fir beetle in scorched and green trees 2 

years following the Clover Mist Fire on the Clarks Fork Ranger District, Shoshone 

National Forest, Wyoming. USDA Forest Service FPM R2-91-01. 20 pp. 

Peet, R.K. 1988. Forests of the Rocky Mountains. In: M.G. Barbour and W.D. 

Billings (eds.) North American terrestrial vegetation. Cambridge University Press, 

New York. Pp. 46-101. 

Peterson, D.L. 1985. Crown scorch volume and scorch height: estimates of 

postfire tree condition. Canadian Journal of Forestry 15:596-598. 

Peterson, D.L. and M.J. Arbaugh. 1986. Postfire survival in Douglas-fir and 

lodgepole pine: comparing the effects of crown and bole damage. Canadian 

Journal of Forest Research 16: 1175-1179. 

Peterson, D.L. and M.J. Arbaugh. 1989. Estimating postfire survival of Douglasfir in the Cascade Range. Canadian Journal of Forest Research19: 530-533. 

Rasmussen, L.A., G.D. Amman, J.C. Vandygriff, R.D. Oakes, A.S. Munson, and 

K.E. Gibson. 1996. Bark beetle and wood bores infestation in the Greater 

Yellowstone Area during four postfire years. USDA Forest Serevice. 

Intermountain Research Station. Research Paper INT-RP-487. 9 pp. 

Reinhardt, E.D. and K.C. Ryan. 1988. How to estimate tree mortality resulting 

from underburning. Fire Management Notes 49: 30-36. 

Romme, R.W. and D.H. Knight. 1981. Fire frequency and sub-alpine forests of 

Yellowstone National Park. Ecological Monographs 52: 199-221. 

Ryan, K.C. 1982. Evaluating potential tree mortality from prescribed burning. In: 

Baumgartner, D.M. (ed) Site Preparation and Fuels Management on Steep 

Terrain. WSU Cooperative Ext. Ser., Pullman, WA. pp. 167-179. 

Ryan, K.C., D.L. Peterson, and E.D. Reinhardt. 1988. Modeling long-term firecaused mortality of Douglas-fir. Forest Science 34: 190-199. 
32

Ryan, K.C. and G.D. Amman. 1994. Interactions between fire-injured trees and 

insects in the Greater Yellowstone Area. In: D.G. Despain (ed.) Plants and their 

environments, proceeding of the first biennial scientific conference of the Greater 

Yellowstone ecosystem. Technical Report NPS/NRYELL/NRTR/93XX. Denver, 

CO: U.S. Department of the Interior, National Park Service: 259-271. 

Ryan, K.C. and G.D. Amman. 1996. Bark beetle activity and delayed tree 

mortality in the greater Yellowstone area following the 1988 fires. In: J. Greenlee 

(ed.) The Proceedings of the Second Biennial Conference on the Greater 

Yellowstone Ecosystem: The Ecological Implications of Fire in Greater 

Yellowstone. September 19-21, 1993, Yellowstone National Park, Wyoming. 

Ryan, K.C. Amman, G.D., Greenlee, J.M. 1996. Bark beetle activity and delayed 

tree mortality in the Greater Yellowstone area following the 1988 fires. In: J. 

Greenlee (ed.) Proceedings of the Second Biennial Conference on the Greater 

Yellowstone Ecosystem: The Ecological Implications of Fire in Greater 

Yellowstone. Yellowstone National Park, Wyoming, USA, 19-21 September, 

1993. 

Salman, K.A. 1933. Entomological factors affect salvaging of fire injured trees. 

Journal of Forestry 32:1016-1017. 

Sall, J. and A. Lehman. 1996. JMP Start Statistics: A Guide to Statistics and Data 

Analysis Using JMP and JMP IN® Software. SAS Institute Inc. Carey, NC 522 

pp. 

SAS. 1995. JMP Statistics and Graphics Guide. SAS Institute Inc. Carey, NC. 

Pp.116-121. 

Stuart, J.D., J.K. Agee, and R.I. Gara. 1989. Lodgepole pine regeneration in an 

old, self-perpetuating forest in south central Oregon. Can. Canadian Journal of 

Forest Research 19: 1096-1104. 

Wagener, W. 1961. Guidelines for Estimating the Survival of Fire-Damaged 

Trees in California. USDA FS Misc. Paper No. 60, Pac. South West Forest and 

Range Experimental Station, Berkeley, California. 11pp. 

Weatherby, J.C., P. Mocettini and B.R. Gardner. 1994. A biological evaluation of 

tree survivorship within the Lowman fire boundary. 1989-1993. USDA Forest 

Service Report # R4-94-06. 9pp. 

Wyant, J.G. 1986. Fire induced tree mortality in a Colorado ponderosa 

pine/Douglas-fir stand. Forest Science 32: 49-59.