United States

Department of

Agriculture

Forest Service

Pacific Northwest

Research Station

General Technical

Report

PNW-GTR-530

February 2002

The Status of Whitebark Pine

Along the Pacific Crest

National Scenic Trail on the

Umpqua National Forest

Ellen Michaels Goheen, Donald J. Goheen, Katy Marshall,

Robert S. Danchok, John A. Petrick, and Diane E. White

Forest Health Monitoring

West Coast Region
Ellen Michaels Goheen, Donald J. Goheen, and Katy Marshall are plant 

pathologists, U.S. Department of Agriculture, Forest Service, Southwest Oregon

Forest Insect and Disease Service Center, 2606 Old Stage Road, Central Point, OR

97502; Robert S. Danchok is a biological technician and John A. Petrick is a 

silviculturist, U.S. Department of Agriculture, Forest Service, Dorena Forest Genetics

Resource Center, 34963 Shoreview Road, Cottage Grove, OR 97424; and Diane E.

White is an ecologist, U.S. Department of Agriculture, Forest Service, Southwest

Oregon Ecology Group, 2900 NW Stewart Parkway, Roseburg, OR 97470.

Cover photo: Mount Thielsen as viewed from Mount Bailey. Photograph by Robert

Danchok.

Authors
Goheen, Ellen Michaels; Goheen, Donald J.; Marshall, Katy; Danchok, Robert S.;

Petrick, John A.; White, Diane E. 2002. The status of whitebark pine along the

Pacific Crest National Scenic Trail on the Umpqua National Forest. Gen. Tech.

Rep. PNW-GTR-530. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 21 p.

Because of concern over widespread population declines, the distribution, stand 

conditions, and health of whitebark pine (Pinus albicaulis Englem.) were evaluated

along the Pacific Crest National Scenic Trail on the Umpqua National Forest. Whitebark pine occurred on 76 percent of the survey transects. In general, whitebark pine

was found in stands with lower overall densities and fewer late-seral species, particularly Shasta red fir (Abies magnifica var. shatensis A. Murr.) and mountain hemlock

(Tsuga mertensiana [Bong.] Carr.). Whitebark pine stocking differed widely, from less

than 1 up to 24 percent of the trees on transect plots. Most whitebark pines (87 percent) were less than 5 m tall. Of all whitebark pine encountered, 44 percent were

alive and healthy, 46 percent were alive but infected by Cronartium ribicola (J.C.

Fisch) (cause of white pine blister rust), and 10 percent were dead. Two-thirds of 

the mortality was due to white pine blister rust. Mountain pine beetle (Dendroctonus

ponderosae Hopkins) alone accounted for 13 percent of the mortality, whereas 

evidence of mountain pine beetle was found with white pine blister rust on 18 percent

of the dead whitebark pines.

White pine blister rust affected trees in all but the largest size class; 70 percent of 

the whitebark pines greater than 1.5 m tall and less than 7.6 cm diameter at breast

height (d.b.h.) were infected. Most (92 percent) of infected whitebark pines had bole

cankers or cankers within 15 cm of the bole. No cones were observed on whitebark

pines in any of the survey plots. Whitebark pine was common in centers of laminated

root rot (caused by the fungus Phellinus weirii (Murrill.) R.L. Gilbertson) where 

substantial canopy openings were found. In these centers, whitebark pine contributed

73 percent of the large tree stocking. The results of this survey constitute a reference

condition for whitebark pine that can be used to assess change in its status in this

part of southwest Oregon. Measures to reduce the impacts of disease and bark 

beetles and to maintain whitebark pine populations are discussed.

Keywords: Whitebark pine, Pinus albicaulis, white pine blister rust, Cronartium 

ribicola, mountain pine beetle, Dendroctonus ponderosae, Umpqua National Forest.

Abstract
1

Whitebark pine (Pinus albicaulis Engelm.) is an important high-elevation forest

species in southwestern Canada and the Western United States (Arno and Hoff

1990). It tolerates extreme environmental conditions and may act as a nurse tree,

modifying microclimatic conditions so that other, less hardy plant species can become

established. It is important for watershed protection, catching and retaining snow, and

stabilizing rock and soil on harsh, open areas. It provides cover and roosting sites for

wildlife and has considerable aesthetic value (fig. 1). Its large nutlike seeds are high

in fat and protein and are important food sources for many mammals and birds.

Whitebark pine belongs to the group of pines known as the “bird pines.” These pines

have wingless or nearly wingless seeds and depend on the caching or planting of

seeds by nutcrackers or jays for regeneration. Whitebark pine is almost entirely

dependent on the Clark’s nutcracker (Nucifraga columbiana Wilson) for its regeneration. Clark’s nutcrackers have strong bills that can extract seed from cones, throat

pouches that can hold up to 100 seeds, and highly developed long-term memories

(Tomback et al. 1990). They use their bills to dig sites for seeds in mineral soils, and

they thrust seeds into sandy soil or loose substrates. They cache seeds in various

sites, including loose gravelly soil and forest litter; at the base of trees, rocks, and

logs; among roots; under rocky rubble; and in holes in trunks or bark of trees. Caching

sites have been observed across a wide range of elevations, in burns, harvested

areas, forest openings, along lake shores, meadow edges, and on cliffs. Nutcrackers

will fly as far as 22 km to cache seeds.

Introduction

Figure 1—Whitebark pine (Pinus albicaulis

Engelm). (Photo by Tom Iraci.)
Whitebark pine is slow growing and long lived. At treeline, whitebark pine forms

“krummholz” stands of shrublike trees (McCaughey and Schmidt 1990). Below the

krummholz zone, whitebark pine grows in nearly pure stands of widely spaced trees

with diffuse crowns (fig. 2a). At its lower elevations, whitebark pine grows in mixedspecies stands where it may be difficult to distinguish its form from that of lodgepole

pine (P. contorta Dougl. ex Loud.) or western white pine (P. monticola Dougl. ex D.

Don) (fig. 2b). Whitebark pine seedlings and saplings often are found growing in 

tight clumps of two or more stems resulting from sprouting of multiseed caches.

There is widespread concern about the status of whitebark pine throughout the West.

In the northern Rocky Mountains, whitebark pine has declined over the past 60 years

because of three interrelated factors: (1) epidemics of the native insect mountain pine

beetle (Dendroctonus ponderosae Hopkins); (2) dieback and mortality caused by the

introduced pathogen Cronartium ribicola (J.C. Fisch), the cause of white pine blister

rust; and (3) replacement of whitebark pine by shade-tolerant conifers probably

because of fire exclusion (Keane and Arno 1993, Kendall and Arno 1990). In some

locations on the east side of Glacier National Park and in the Selkirk Range of 

northern Idaho, 90 percent of the whitebark pine has been killed. Surveys recently 

completed in the northern portion of the Intermountain region indicate high white pine

blister rust infection levels and the onset of mortality of whitebark pine in many areas

(Smith and Hoffman 1998). Particular concerns include increased whitebark pine

2

Figure 2—Along the Pacific Crest National Scenic Trail on the Umpqua National Forest, whitebark pine 

is found in predominantly pure stands at higher elevations (A) and at lower to mid elevations in mixed

stands with mountain hemlock, lodgepole pine, western white pine, Pacific silver fir, and Shasta red fir (B).

(Photos by Ellen Goheen (left) and Robert Danchok (right).)

A B
mortality in the western and southern portions of the Greater Yellowstone ecosystem

and high white pine blister rust levels in the Centennial Mountains on the MontanaIdaho border where whitebark pine populations are small, disjunct, and therefore

potentially vulnerable to extinction.

Recent evaluations of whitebark pine growing in pure stands as well as in mixedspecies stands in northeastern Oregon indicate a range of white pine blister rust

infection levels as well as a varied history of mountain pine beetle outbreaks (Schmitt

and Scott 1998). White pine blister rust is described as severe on some sites;

mortality, particularly among smaller size classes, is readily apparent.

Several whitebark pine sites in eastern Washington also have been surveyed recently

to determine cause and level of whitebark pine mortality.1 Overall mortality of whitebark pine was 12.5 percent; white pine blister rust was the most common cause.

White pine blister rust was found on 18.9 percent of the whitebark pines examined.

Although whitebark pine is an important species in the southern Oregon Cascade

Range, its condition in this area has not been rigorously evaluated. White pine blister

rust came later to the region, relative to other areas with whitebark pine in the Pacific

Northwest; as of 1943, it was not known to affect whitebark pine south of Mount

Jefferson (Bedwell and Childs 1943). Recent anecdotal accounts suggest that both

mountain pine beetle and white pine blister rust profoundly influence the health of

whitebark pine, but no quantitative information is available.

The objectives of this investigation were to (1) determine the distribution of whitebark

pine along the Pacific Crest National Scenic Trail (PCNST) in the southern Oregon

Cascade Range, (2) characterize site and stand conditions where whitebark pine

occurs, (3) evaluate the current health of the species, and (4) establish a benchmark

of information for comparison in the future.

During summer 1998, personnel from the Southwest Oregon Forest Insect and

Disease Service Center, the Dorena Forest Genetics Resource Center, and the

Southwest Oregon Ecology Group began a cooperative effort to assess the condition

of whitebark pine in southwest Oregon. We chose the portion of the PCNST on the

Umpqua and Winema National Forests and extending from the southern boundary of

the Willamette National Forest to the northern boundary of Crater Lake National Park

for an initial evaluation (T. 25, 251/2, 26, 27, and 28 S., R. 51/2, 6, and 61/2 E.) 

(fig. 3). Concentrations of whitebark pine were known to be present along this portion

of the PCNST, and the area was relatively easily accessed from a series of side trails.

3

1Hadfield, James; Flanagan, Paul. 2000. Personal communication.

Plant pathologist and entomologist. Forest Health Protection,

Wenatchee Service Center, Forestry Sciences Lab, 1133 N.

Western Ave., Wenatchee, WA 98801.

Methods
4

PCNS Trail

Plot

▼

▼

▼

▼

▼

Figure 4—Whitebark pine survey

transect design.

Figure 3—General location of survey area in southwest Oregon and survey transect locations along the

Pacific Crest National Scenic Trail, Umpqua National Forest.
Transects were installed along the PCNST at each intersection with an east-west 

section line (fig. 3). The location of each of the 21 transects was determined by 

topographic features and pacing and was recorded by using a global positioning 

system device. The transect direction (due east or west of the trail) was randomly

determined. Each transect consisted of eight plots systematically located in a 

U-shaped grid (fig. 4). On each transect, two types of plots were established—six

whitebark pine plots and two plots where whitebark pine data plus additional information on all tree species was collected (fig. 5). Data on environmental variables such

as plant association (Atzet et al. 1996), slope, aspect, elevation, and topographic 

position, also were collected on each plot.

Variable-radius plots—A 20-basal-area factor (BAF) variable-radius plot was 

established for trees greater than 12.7 cm d.b.h. All whitebark pine trees were 

measured. Other trees were tallied by species.

Fixed-area plots—Circular 0.02-ha plots were established to record whitebark pine

trees less than 12.7 cm d.b.h., the number of Ribes sp. plants present (the alternate

host of C. ribicola), and the current root disease severity (table 1).

5

Whitebark Pine Plots

Figure 5—Crews collected data at eight plots on each sampling transect. (Photo by Ellen Goheen.)
Table 1—Disease severity rating for plots and trees

Severity Rating

rating definition

Root disease (0.02-ha circular plots):

0 No evidence of root disease

1 Root disease not on plot, but present within 15 m of plot edge

2 Minor evidence of root disease (i.e., one suppressed tree killed)

3 Canopy reduction up to 20 percent

4 Canopy reduction 20 to 30 percent

5 Canopy reduction 30 to 50 percent

6 Canopy reduction 50 to 75 percent

7 Over 75 percent canopy reduction

8 Only 1 overstory tree remaining due to root disease

9 No overstory trees remaining

Whitepine blister rust (individual trees):

1 Distance from nearest margin of branch canker to stem >61 cm, nonlethal 

canker.

2 Distance from nearest margin of branch canker to stem between 15 and 

61 cm.

3 Distance from nearest margin of branch canker to stem <15 cm or canker is 

on bole.

The following data were collected for each whitebark pine tree: condition (living or

dead), diameter to the nearest 0.25 cm, height to the nearest 0.3 m, crown ratio,

crown class, white pine blister rust canker severity rating (table 1) for the most lethal

canker, height to the nearest 0.3 m for the highest white pine blister rust canker, 

percentage of crown with white pine blister rust cankers, percentage of topkill caused

by white pine blister rust, indicators of rodent gnawing on cankers, presence of cones,

and other insects and diseases present.

6
Table 2—Environmental distribution of whitebark pine

Elevation Aspect Slope Slope position Plant

range range range median association

Plot category mean (STD) median mean (STDa) location occurrence

Meters Degrees Percent Percent

Total study area 1768-2320 8-360 1-80 Upper third TSME14d 78

2024 (149) 227 24 (16) TSME16e 10

ABMA22f 8

PICO8g 4

Large whitebark 1783-7610 150-334 2-56 Upper third TSME14 75

pinesb 2063 (184) 227 21 (15) TSME16 20

ABMA22 5

PICO8 0

Small whitebark 1780-2304 30-338 2-55 Upper third TSME14 71

pinesc 2003 (146) 222 20 (14) TSME16 23

ABMA22 6

PICO8 0

a STD = Standard deviation.

b ≥12.7 cm d.b.h. c <12.7 cm d.b.h.

d TSME14 = Mountain Hemlock/Grouse Huckleberry/Common Prince’s-pine plant association.

e TSME16 = Mountain Hemlock/Pinemat Manzanita/Common Prince’s-pine plant association.

f ABMA22 = Shasta Red Fir-Mountain Hemlock/Pinemat Manzanita/Common Prince’s-pine plant 

association.

g PICO8 = Lodgepole Pine-Mountain Hemlock/Depauperate plant association.

Variable-radius plots—A variable-radius plot was established by using a 20-BAF

prism to record all trees greater than 12.7 cm d.b.h. Tree species and diameter to the 

nearest 0.25 cm were recorded.

Fixed-area plots—Circular 0.02-ha plots were established to record the number of

Ribes sp. plants present and a root disease severity rating (table 1). Circular 0.004-ha

plots were used to tally condition of all trees of any species less than 12.7 cm d.b.h.

White pine blister rust canker severity rating for the most lethal canker was recorded

on infected western white pine (table 1). Trees were grouped into the following 

diameter classes: (a) trees between 15 cm and 1.3 m tall, (b) trees 0.25 to 2.3 cm

d.b.h., (c) trees 2.5 to 7.4 cm d.b.h., and (d) trees 7.5 to 12.5 cm d.b.h.

Four plant associations were recorded in the study area: Mountain Hemlock/Grouse

Huckleberry/Common Prince’s-pine (TSME14), Mountain Hemlock/Pinemat

Manzanita/Common Prince’s-pine (TSME16), Shasta Red Fir-Mountain

Hemlock/Pinemat Manzanita/ Common Prince’s-pine (ABMA22), and Lodgepole 

Pine-Mountain Hemlock/Depauperate (PICO8). Whitebark pine occurred in the

Mountain Hemlock and Shasta Red Fir plant associations in proportion to its 

abundance across the landscape. Whitebark pine was not found in the Lodgepole

Pine association, although the sample size was small (table 2).

Plot elevations ranged from 1758 to 2306 m, with a mean of 2012 m. Both large

(>12.7 cm d.b.h) and small (<12.7 cm d.b.h) whitebark pines were distributed over 

this elevation range (table 2).

7

All-Tree-Species Plots

Results

Distribution of

Whitebark Pine
Table 3—Tree species composition of area sampled based on all-tree-species

plot data

Plot Shasta Pacific Lodgepole Western Mountain Whitebark

category Plots red fir silver fir pine white pine hemlock pine

Basal area: - - - - - - - - - - - - - - - - - - - - - - - Meters2 per hectare - - - - - - - - - - - - - - - - - - - - - - - 

Total, all-treespecies plots 42 4.7a 0.1 6.8 1.7 47.9 0.6

(0.7) (0.02) (1.1) (0.3) (7.9) (0.1)

All-tree-species

plots with 

whitebark pine 18 1.3 0 7.1 1.5 33.2 1.3

present (0.3) (0) (1.7) (0.4) (7.8) (0.3)

Trees per hectare: - - - - - - - - - - - - - - - - - - - - - - - Trees per hectare - - - - - - - - - - - - - - - - - - - - - - - 

Total, all-treespecies plots 42 252.3 0 334.3 75.1 1,233.5 111.7

(39.0) (0) (51.6) (11.6) (190.3) (28.2)

All-tree-species

plots with 

whitebark pine 18 92.4 0 350.1 65.2 821.1 260.4

present (21.7) (0) (82.5) (15.3) (193.2) (46.9)

a The mean value is given with the standard error in parentheses below it. Basal area is calculated for trees

of 12.7 cm d.b.h. or more. Trees per hectare include trees in all size classes.

Study plots were located on virtually all aspects. Large whitebark pines occurred on

aspects between 150 and 334 degrees, and small whitebark pines between 30 and

338 degrees. No whitebark pines were recorded on the most northerly aspects (338

to 30 degrees), and only smaller trees were found on the east aspects (30 to 150

degrees) (table 2). The percentage of slope of the plots ranged from 1 to 80 percent,

with a mean of 24 percent. Both large and small whitebark pines were found on

slopes up to 55 percent, but none were found on the steeper slopes (57 to 80 percent). The median slope position found in the study was the upper third of slope,

where whitebark pines also occurred most frequently.

Whitebark pine occurred on 76 percent of the transects. Five tree species occurred

with whitebark pine: Shasta red fir (Abies magnifica var. shastensis A. Murr.), Pacific

silver fir (A. amabilis Dougl. ex Forbes), lodgepole pine, western white pine, and

mountain hemlock (Tsuga mertensiana (Bong.) Carr.). Mountain hemlock was clearly

the predominant species.

Table 3 shows species occurrence over all the tree-species plots compared with only

those tree-species plots where whitebark pine was present. The basal area data are

based on results for only the large trees (d.b.h >12.7 cm), whereas the stocking data

(trees per hectare) are derived from trees in all size classes. In general, whitebark

pine occurs in stands with lower overall densities and fewer late-seral species. Shasta

red fir and mountain hemlock are less abundant on plots with whitebark pine than on

other plots.

8

Stand Characteristics
Table 4—Live tree stocking (trees per hectare) by species and transect

Transect ABMASa ABAMb PICOc PIMOd TSMEe PIALf Total

1 415 0 203 143 8,972 262 9,995

2 4,490 0 185 57 2,646 7 7,393

3 9,558 0 0 128 2,896 0 12,582

4 262 0 168 49 1,334 15 1,829

5 3,857 0 0 324 1,043 0 5,224

6 494 0 0 124 635 227 1,480

7 124 0 0 0 5,243 40 5,407

8 153 0 195 2 3,005 138 3,494

9 0 0 5,112 0 7,149 484 12,745

9.5 0 0 1,112 0 2,412 509 4,033

10 0 0 0 0 1,198 52 1,250

11 0 0 324 0 749 222 1,295

12 0 0 0 0 6,239 44 6,284

13 0 0 0 0 3,941 106 4,047

14 0 0 0 0 1,463 136 1,599

15 0 0 2,995 0 2,150 148 5,293

16 0 0 141 0 8,527 0 8,668

17 492 0 633 49 5,243 0 6,417

18 502 0 484 0 3,924 0 4,910

19 0 0 326 10 331 208 875

20 0 1,619 568 72 714 111 3,084

Mean 969 77 652 46 3,325 129 5,138

Standard error 506 77 271 17 577 33 795

a ABMAS = Shasta red fir.

b ABAM = Pacific silver fir.

c PICO = lodgepole pine.

d PIMO = western white pine.

e TSME = mountain hemlock.

f PIAL = whitebark pine.

Stocking levels for all the tree species varied widely among individual transects. Total

stocking on individual transects ranged from 875 to 12,745 trees per hectare (table 4).

Average basal area for all species on individual transects ranged from 27.0 to 76.9 m2

per ha (table 5).

Whitebark pine stocking varied widely among transects (table 4). Where whitebark

pine occurred, stocking for living and dead trees of all sizes ranged from 7 to 509,

with an average of 169 trees per hectare. Whitebark pine stocking represented from

less than one percent up to 24 percent of the total trees per hectare. When only

small trees (<12.7 cm d.b.h) were considered, whitebark pine stocking ranged from

less than one percent to 32 percent of the trees per hectare.

9

Whitebark Pine

Stocking
Table 5—Live tree basal area (square meters per hectare) by species and 

transect

Transect ABMASa ABAMb PICOc PIMOd TSMEe PIALf Total

1 2.9 0 6.9 4.6 15.5 2.9 32.7

2 25.8 0 1.1 5.2 21.8 0 54.0

3 4.6 0 0 1.1 71.2 0 76.9

4 20.1 0 1.7 3.4 43.1 .6 68.9

5 25.8 0 0 1.7 25.8 0 53.4

6 0 0 1.1 .6 46.5 .6 49.9

7 0 0 4.6 .6 54.0 0 59.1

8 1.1 0 8.0 1.1 36.2 0 46.5

9 0 0 6.9 0 19.5 .6 27.0

9.5 0 0 1.1 0 43.1 .6 44.8

10 0 0 1.7 0 53.4 0 55.1

11 0 0 2.3 0 28.7 3.4 34.4

12 0 0 0 0 45.3 0 45.3

13 0 0 0 0 56.3 1.7 58.0

14 0 0 0 0 60.8 1.1 62.0

15 0 0 8.0 0 30.4 1.7 40.2

16 0 0 3.4 0 55.1 0 58.5

17 5.2 0 32.1 4.6 10.3 0 52.2

18 6.9 0 6.9 0 57.4 0 71.2

19 0 0 2.3 2.3 48.2 .6 53.4

20 0 2.9 5.7 1.1 41.9 .6 52.2

Mean 4.4 .7 4.5 1.3 41.2 .7 52.2

Standard error 1.9 .6 1.5 .4 3.6 .2 2.8

a ABMAS = Shasta red fir.

b ABAM = Pacific silver fir.

c PICO = lodgepole pine.

d PIMO = western white pine.

e TSME = mountain hemlock.

f PIAL = whitebark pine.

Eighty-seven percent of all whitebark pine measured were less than 5 m tall. The

largest whitebark pine tree measured on survey plots was 68 cm d.b.h. Larger 

individuals were occasionally encountered in surrounding stands.

White pine blister rust occurred on all transects with whitebark pine (figs. 6, 7, and 8).

Across the entire survey area, 44 percent of all whitebark pine encountered were alive

and healthy, 46 percent were alive but infected by C. ribicola, and 10 percent were

dead (fig. 8) 

On individual transects, white pine blister rust occurrence on living trees varied widely,

ranging from zero to 100 percent (table 6).

10

Whitebark Pine

Health
11

Figure 6—Whitebark pine is frequently infected and

killed by white pine blister rust. (Photo by Robert

Danchok.)

Figure 7—Infections of the bole by Cronartium 

ribicola, cause of white pine blister rust, are considered lethal. Note “blisters” of rust spores erupting

from bark of this whitebark pine tree. (Photo by

Ellen Goheen.)

Figure 8—Percentage of whitebark pine 

by condition classes. WPBR = white pine 

blister rust.
Table 6—Whitebark pine stocking (trees per hectare) by condition and transect

Live Dead

____________________ ________________________________________

Infected WPBR and

Transect Uninfected WPBRa WPBR MPBb MPB Other

1 37.1 224.9 19.8 4.9 0 0

2 0 7.4 0 7.4 0 0

4 14.8 0 7.4 0 0 0

6 135.9 91.4 44.5 0 17.3 0

7 7.4 32.1 24.7 32.1 0 0

8 69.2 69.2 0 0 2.5 0

9 197.7 286.6 37.1 0 0 0

9.5 254.5 254.5 19.8 4.9 0 0

10 44.5 7.4 0 0 0 0

11 138.4 84.0 0 0 0 0

12 37.1 7.4 0 0 0 0

13 32.1 74.1 0 0 4.9 0

14 74.1 61.8 7.4 0 0 7.4

15 86.5 61.8 0 0 0 0

19 131.0 76.6 17.3 0 9.9 0

20 56.8 54.4 0 0 0 0

Mean 82.3 87.1 11.1 3.1 2.2 .5

Standard error 17.9 22.3 3.6 2.0 1.2 .5

a WPBR = white pine blister rust.

b MPB = mountain pine beetle.

White pine blister rust affected trees in all but the largest size class (trees >51 cm

d.b.h) (fig. 9). Infection levels were low in trees between 15 cm and 0.6 m tall. On the

other hand, 70 percent of the whitebark pines greater than 1.5 m tall and less than

7.6 cm d.b.h were infected.

12

Figure 9—Percentage of whitebark pine by size and condition class (uninfected, infected with white pine

blister rust (WPBR), or dead).
Most (92 percent) of the infected whitebark pine were classified as WPBR severity 

rating 3; they had bole cankers or cankers within 15 cm of the bole (fig. 10). Eight

percent of infected trees had cankers located between 15 and 61 cm from the bole

(severity rating 2), and less than one percent of the infected trees had cankers at a

distance greater than 61 cm from the bole (severity rating 1).

Thirty-four percent of all live whitebark pines with white pine blister rust had been topkilled (fig. 11); the proportion of the top that had been killed was greater than 30 percent of the height of the tree in 43 percent of the trees with topkill. Topkill excluded,

white pine blister rust cankers commonly killed branches constituting 10 to 20 percent

of the live crown. Cankers were found throughout the heights of the trees (fig. 12).

White pine blister rust was the most frequently encountered whitebark pine mortality

agent, accounting for 66 percent of all dead trees (table 6). Evidence of mountain

pine beetle was found with white pine blister rust on 18 percent of dead whitebark

pines. Mountain pine beetle alone killed 13 percent of the whitebark pine examined 

in the survey (fig. 13). The largest whitebark pine (68 cm d.b.h) measured in survey

plots had recently been killed by mountain pine beetles. Other large whitebark pine

snags of various age and decay categories were observed in the surrounding stands.

Many showed evidence of attack by mountain pine beetles.

13

Figure 10—Percentage of whitebark pine 

by white pine blister rust severity classes.

Figure 11—Tops of about a third of the whitebark

pine in the Umpqua Pacific Crest National Scenic

Trail survey were killed by white pine blister rust.

(Photo by Ellen Goheen.)
14

Figure 12—Height of highest white pine blister rust cankers on whitebark pine, by tree height.

Figure 13—Mountain pine beetles frequently contribute to mortality of whitebark pine. (Photo by Ellen

Goheen.)
Table 7—Number of plots in root disease severity rating categories

Root disease

severity rating 0 1 2 3 4 5 6 7 8 9

Number of plots 96 13 19 11 8 11 4 3 2 1

Only one Ribes plant was encountered across the entire survey area. It was found

along the PCNST near one of the few springs in the area but was not associated with

any transect or survey plot.

Evidence of rodents chewing on white pine blister rust cankers was seen on only four

trees measured in the survey.

No cones were observed on whitebark pines in any of the survey plots.

Laminated root rot (caused by the fungus Phellinus weirii (Murrill) R.L. Gilbertson)

was found on 59 (35 percent) of the survey plots (fig. 14). Canopy reduction caused

by laminated root rot was considered minor (RDSR = 2) on 19 plots, moderate 

(RDSR = 3, 4, or 5) on 30 plots, and high (RDSR = 6, 7, 8, or 9) on 10 plots (table 7).

Mountain hemlock, a highly susceptible species, was the main tree being impacted by

P. weirii.

Whitebark pines occurred on only 32 percent of all plots with root disease (RDSR ≥ 2),

but that frequency more than doubled to 70 percent of the plots with high levels of

canopy reduction due to root disease (RDSR > 6). On these plots, whitebark pines

comprised 49 percent of the stocking for trees of all sizes, followed by lodgepole pine

15

Root Disease

Figure 14—Whitebark pine is an important pioneer species inside openings caused by laminated root rot.

(Photo by Ellen Goheen.)
(39 percent), and western white pine (12 percent). Seventy-three percent of the trees

greater than 25 cm d.b.h. found in plots with high RDSR were whitebark pines; the

remainder were western white pines. There was no evidence of damage to whitebark

pine, western white pine, or lodgepole pine owing to P. weirii in this survey.

Anecdotal accounts are no longer the only source of whitebark pine information along

the PCNST on the Umpqua National Forest. The 1998 reference condition for whitebark pine described in this report can be used for assessing changes in the status of

the species in this area.

Along this portion of the PCNST, whitebark pine usually occurs as a minor component

in predominantly mixed-species stands, but stocking levels are variable. Higher 

frequencies of whitebark pine on upper slope south-facing sites; open, rocky ridgetops; in areas with increased lodgepole pine stocking levels; and in openings created

by laminated root rot point to its affinity for areas of recent disturbance and open

stand conditions.

Half of the whitebark pine stocking is currently infected by C. ribicola. White pine 

blister rust is obviously having a significant effect on form and function of whitebark

pine; two-thirds of current mortality is due to C. ribicola. Topkill caused by the fungus

is affecting height growth in an already slow-growing species; substantial portions of

the main stems are dead, and lateral branches are competing to replace the leaders.

The high proportion of trees with cankers near or on the bole suggests that there will

be considerably more topkill and tree mortality.

No obvious, distinct pattern indicating wave-year C. ribicola infections was observed 

in this survey, but no systematic attempt was made to age white pine blister rust

cankers. The lack of Ribes spp. present near infected trees and in the survey area 

in general, as well as the distribution of white pine blister rust cankers throughout 

the heights of infected trees, strongly support the hypothesis that the C. ribicola

basidiospores that infect pine in the survey area originate in other locations and are

brought to the area via clouds and fog. Such environmental conditions are common

in late summer and early autumn in the southern Oregon Cascade Range, particularly

at the higher elevations. Thus, white pine blister rust likely will continue to cause

branch dieback, topkill, and mortality in these whitebark pine forests.

Although no whitebark pine cones were observed on plot trees during the 1998 

survey, cones were present on scattered whitebark pines observed outside the plots.

Numbers of cone-producing whitebark pines will undoubtedly be influenced by the

presence of white pine blister rust. Topkill in larger trees physically reduces the conebearing portion of the tree, and fewer trees surviving to cone-bearing age will result in

fewer cones produced overall.

Larger diameter whitebark pines have been killed both recently and in the past by

mountain pine beetles operating alone or in conjunction with white pine blister rust.

Mountain pine beetles typically attack and kill mature whitebark pine; individual tree

mortality associated with endemic population levels involves weaker, less vigorous

trees (Furniss and Carolin 1977). More than half of the trees killed by mountain pine

beetles in the survey area also had evidence of C. ribicola infection. There was little

evidence of white pine blister rust on dead trees greater than 51 cm d.b.h., but

16

Discussion
because most of these trees had been dead for a considerable time, detection of past

disease was extremely difficult. In other areas of the West, it has been shown that,

during outbreaks, whitebark pine stands are often infested by mountain pine beetles

originating in lower elevation lodgepole pine stands (Bartos and Gibson 1990).

Relatively pure lodgepole pine stands were found in the survey area.

In several openings created by laminated root rot, whitebark pine, which is resistant 

to P. weirii, was the only regenerating species. On one of these plots, however, all 

the whitebark pines were infected by C. ribicola. On other plots with extensive root 

disease, lodgepole pine and western white pine, also highly resistant to P. weirii, were

also present. Although western white pine was not sampled intensively in this survey,

limited data indicate that 63 percent of the western white pines were infected by 

C. ribicola as well. Thus it seems reasonable to assume that the dynamics of trees

inside openings created by laminated root rot are, and will continue to be, substantially altered owing to the impacts of white pine blister rust. Regeneration of rootdisease-resistant species will shift from a mix of resistant pine species to predominantly lodgepole pine. Stocking levels may be reduced inside root disease pockets

where lodgepole pine is unavailable or unsuitable for the site. Large tree structure in

root disease pockets in stands of whitebark pine and western white pine will decrease

because of lack of recruitment, mortality and topkill at young ages, and the potential

increased vulnerability of infected large trees to attack by mountain pine beetles.

Although no wildlife-related data on standing dead whitebark pines were collected in 

the survey, woodpeckers were observed excavating in large-diameter (>51 cm. d.b.h.)

dead whitebark pines, and bats were seen emerging from beneath the loose bark of

one large whitebark pine snag. Decreased survival of regeneration, slower growth

rates related to topkill, and mountain pine beetle-caused mortality may affect numbers

of replacement whitebark pine and western white pine snags available to cavity

nesters and other wildlife species. Fewer whitebark pine cones will be available as 

a food source for Clark’s nutcrackers as well as for other birds and mammals.

Our overall impression after completing this investigation is that whitebark pine in 

the survey area is more seriously threatened by white pine blister rust than previously

believed. Maintaining the whitebark pine component in this area seems critical in light

of its importance on certain microsites and in root disease centers.

Possible measures to reduce impacts of white pine blister rust on whitebark pine in

the survey area could include:

• Increased use of prescribed fire for creating openings where pine regeneration 

would be encouraged and host populations might be enlarged sufficiently for 

natural resistance to C. ribicola to emerge.

• Breeding to enhance resistance of phenotypically resistant whitebark pines 

identified in the field, for planting in appropriate locations in an active restoration 

program.

Possible measures to reduce the impacts of mountain pine beetle on whitebark pine

could include:

• Reducing ingrowth of late-seral species, such as mountain hemlock and true firs, 

and reducing the basal area of whitebark pine and lodgepole pine in stands 

mechanically or with fire to increase individual tree vigor.

17
18

• Suppressing mountain pine beetle populations in lower elevation lodgepole pine 

stands to reduce numbers of mountain pine beetles invading higher elevation 

whitebark pine stands.

The area sampled along the PCNST should be revisited to monitor how the structure

and function of whitebark pine forests on the Umpqua National Forest will be influenced by white pine blister rust.

The PCNST on the Umpqua National Forest misses several high-elevation ridges

where whitebark pine grows in essentially pure stands. These sites will be surveyed

in the near future to ascertain how whitebark pines growing under more extreme 

environmental conditions are being affected by white pine blister rust and mountain

pine beetles. Surveys also will be conducted in other parts of southwestern Oregon

as resources become available.

We thank John Schwandt (USDA FS, Coeur d’Alene, ID), James Hoffman (USDA FS,

Boise, ID), and Sally Campbell (USDA FS, Portland, OR) for review of the manuscript.

Funding for this work was provided by the USDA Forest Service, Forest Health

Monitoring Program.

When you know: Multiply by: To find:

Centimeters (cm) 2.54 Inches

Hectares (ha) 2.47 Acres

Kilometers (km) 0.621 Miles

Meters (m) 3.281 Feet

Square meters (m2) 1.20 Square yards 

Arno, S.F.; Hoff, R.J. 1990. Pinus albicaulis Engelm. whitebark pine. In: Burns, R.M.;

Honkala, B.H., tech. coords. Silvics of North America: I. Conifers. Agric. Handb. 654.

Washington, DC: U.S. Department of Agriculture, Forest Service: 268-279. Vol 1.

Atzet, T.; White, D.E.; McCrimmon, L.A. [and others], tech. coords. 1996. Field

guide to the forested plant associations of southwestern Oregon. Tech. Pap. R6-NRECOL-TP-17-96. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Region. 201 p.

Bartos, D.L.; Gibson, K.E. 1990. Insects of whitebark pine with emphasis on 

mountain pine beetle. In: Schmidt, W.; McDonald, K., comps. Whitebark pine 

ecosystems: ecology and management of a high mountain resource: Proceedings of

a symposium. Gen. Tech. Rep. INT-270. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Research Station: 171-178.

Bedwell, J.L.; Childs, T.W. 1943. Susceptibility of whitebark pine to blister rust in the

Pacific Northwest. Journal of Forestry. 41: 904-912.

Furniss, R.L.; Carolin, V.M. 1977. Western forest insects. Misc. Publ. 1339.

Washington, DC: U.S. Department of Agriculture, Forest Service. 654 p.

Acknowledgments

English 

Equivalents

Literature Cited
Keane, R.; Arno, S. 1993. Rapid decline of whitebark pine in western Montana:

evidence from 20-year measurements. Western Journal of Applied Forestry. 8(2):

44-47.

Kendall, K.C.; Arno, S.F. 1990. Whitebark pine: an important but endangered wildlife

resource. In: Schmidt, W.; McDonald, K., comps. Whitebark pine ecosystems:

ecology and management of a high mountain resource: Proceedings of a symposium. Gen. Tech. Rep. INT-270. Ogden, UT: U.S. Department of Agriculture, Forest

Service, Intermountain Research Station: 264-274.

McCaughey W.W.; Schmidt, W.C. 1990. Autecology of whitebark pine. In: Schmidt,

W.; McDonald, K., comps. Whitebark pine ecosystems: ecology and management of

a high mountain resource: Proceedings of a symposium. Gen. Tech. Rep. INT-270.

Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research

Station: 85-96.

Schmitt, C.L.; Scott, D.W. 1998. Whitebark pine health in northeastern Oregon and

western Idaho. Zone Report BMZ-99-03. La Grande, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Region, Wallowa-Whitman National

Forest, Blue Mountain Pest Management Zone. 11 p.

Smith, J.J.; Hoffman, J. 1998. Status of white pine blister rust in Intermountain

Region white pines. Report No. R4-98-02. Boise, ID: U.S. Department of Agriculture,

Forest Service, Intermountain Region, State and Private Forestry. 24 p.

Tomback, D.F.; Hoffman, L.A.; Sund, S.K. 1990. Coevolution of whitebark pine and

nutcrackers: implications for forest regeneration. In: Schmidt, W.; McDonald, K.,

comps. Whitebark pine ecosystems: ecology and management of a high mountain

resource: Proceedings of a symposium. Gen. Tech. Rep. INT-270. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Research Station: 118-

129.

19
20
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