United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

General Technical 

Report RMRS-GTR-279

June 2012

A Range-Wide Restoration Strategy for 

Whitebark Pine (Pinus albicaulis)
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Keane, Robert E.; Tomback, D.F.; Aubry, C.A.; Bower, A.D.; Campbell, E.M.; Cripps, 

C.L.; Jenkins, M.B.; Mahalovich, M.F.; Manning, M.; McKinney, S.T.; Murray, 

M.P.; Perkins, D.L.; Reinhart, D.P.; Ryan, C.; Schoettle, A.W.; Smith, C.M. 2012. 

A range-wide restoration strategy for whitebark pine (Pinus albicaulis). Gen. 

Tech. Rep. RMRS-GTR-279. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station. 108 p.

Abstract

Whitebark pine (Pinus albicaulis), an important component of western highelevation forests, has been declining in both the United States and Canada 

since the early Twentieth Century from the combined effects of mountain pine 

beetle (Dendroctonus ponderosae) outbreaks, fire exclusion policies, and the 

spread of the exotic disease white pine blister rust (caused by the pathogen 

Cronartium ribicola). The pine is now a candidate species for listing under the 

Endangered Species Act. Within the last decade, with major surges of pine beetle 

and increasing damage and mortality from blister rust, the cumulative whitebark 

pine losses have altered high-elevation community composition and ecosystem 

processes in many regions. Whitebark pine is a keystone species because of its 

various roles in supporting community diversity and a foundation species for its 

roles in promoting community development and stability. Since more than 90 

percent of whitebark pine forests occur on public lands in the United States and 

Canada, maintaining whitebark pine communities requires a coordinated and 

trans-boundary effort across Federal and provincial land management agencies to 

develop a comprehensive strategy for restoration of this declining ecosystem. We 

outline a range-wide strategy for maintaining whitebark pine populations in high 

mountain areas based on the most current knowledge of the efficacy of techniques 

and differences in their application across communities. The strategy is written as 

a general guide for planning, designing, implementing, and evaluating fine-scale 

restoration activities for whitebark pine by public land management agencies, 

and to encourage agency and inter-agency coordination for greater efficiency. 

The strategy is organized into six scales of implementation, and each scale is 

described by assessment factors, restoration techniques, management concerns, 

and examples.

Keywords: whitebark pine, ecosystem restoration, fire regime, blister rust, mountain 

pine beetle, grizzly bear, Clark’s nutcracker, seed dispersal, regeneration, red 

squirrels, upper subalpine communities, climate change

The use of trade or firm names in the publication is for reader information and does not imply 

endorsement by the U.S. Department of Agriculture of any product or service.
Executive Summary

Whitebark pine (Pinus albicaulis) forests are declining across most of their range 

in North America because of the combined effects of mountain pine beetle 

(Dendroctonus ponderosae) outbreaks, fire exclusion policies, and the exotic 

pathogen Cronartium ribicola, which infects five-needle white pines and causes 

the disease white pine blister rust. The loss of this high-elevation tree species 

poses serious consequences for upper subalpine ecosystems, both in terms of 

impacts on biodiversity and losses in ecosystem processes; whitebark pine is now 

a candidate species for listing under the Endangered Species Act. Large, nutritious 

seeds produced by whitebark pine are an important food for many bird and 

small mammal species, as well as grizzly (Ursus arctos horribilis) and black bears 

(Ursus americanus), and whitebark pine communities provide habitat for many 

additional wildlife species. Whitebark pine seed dispersal by Clark’s nutcrackers 

(Nucifraga columbiana) combined with hardy seedlings results in early whitebark 

pine community development after fire and other disturbances; whitebark pine 

seedlings survive on harsh, arid sites and may act as nurse trees to less hardy 

conifers and vegetation. Whitebark pine at higher elevations, where it is common 

in many regions, helps regulate snow melt and reduce soil erosion. For these 

collective functions, whitebark pine is considered both a keystone species for 

promoting community diversity and a foundation species for promoting community 

stability. Since more than 90 percent of whitebark pine forests exist on public land 

in the United States and Canada, it is important that government natural resource 

management agencies play an important role in ensuring future presence of this 

tree species by initiating concerted, coordinated, and comprehensive restoration 

efforts. This is best accomplished through a coordinated, trans-boundary restoration 

strategy that includes shared infrastructure and expertise for conserving seeds, 

growing blister rust-resistant seedlings, protecting trees, restoring ecosystem 

processes, and promoting natural regeneration. We detail a multi-scale strategy for 

restoring whitebark pine across its range in the western United States and Canada. 

The strategy was compiled by researchers, land managers, and resource specialists 

for use as a reference for prioritizing, designing, and implementing successful 

whitebark pine restoration activities across many scales from stands to landscapes 

to its entire range. The whitebark pine restoration strategy consists of the following 

principles: (1) promote rust resistance, (2) conserve genetic diversity, (3) save seed 

sources, and (4) employ restoration treatments. These guiding principles are then 

used to implement the whitebark pine restoration strategy using a set of possible 

actions:

1. assess condition,

2. plan activities,

3. reduce pest impacts,

4. gather seed,

5. grow seedlings,

6. protect seed sources,

7. implement restoration treatments,

8. plant burned areas,

9. support research, and

10. monitor activities.

The strategy is also organized by six spatial scales of analysis and organization:

1. range-wide,

2. region (National Forest Region or Provincial Regions),

3. forest (National Forest, National Park, and Canadian Forest District),

4. landscape (watershed or landform),

5. stand, and

6. tree.

At each scale, we present four important factors in the restoration strategy: (1) 

assessment, (2) restoration actions, (3) management concerns, and (4) an example. 

Strategic restoration plans are presented for the coarse-scale strategies, while 

illustrated examples are presented for the finer scales (tree, stand, and landscape).

i
ii

Authors

Robert E. Keane is a Research Ecologist with the U.S. Forest Service, Rocky Mountain Research 

Station at the Missoula Fire Sciences Laboratory in Missoula, Montana. His most recent research 

includes (1) developing ecological computer simulation models for exploring landscape, fire, 

and climate dynamics, (2) sampling, describing, modeling, and mapping fuel characteristics, 

and (3) investigating the ecology and restoration of whitebark pine. He received his B.S. degree 

in Forest Engineering from the University of Maine, Orono; his M.S. degree in Forest Ecology 

from the University of Montana, Missoula; and his Ph.D. in Forest Ecology from the University 

of Idaho, Moscow.

Diana F. Tomback is a Professor in the Department of Integrative Biology University of Colorado 

Denver, an Evolutionary Ecologist and Conservation Biologist, and volunteer Director of the 

Whitebark Pine Ecosystem Foundation, a non-profit organization based in Missoula, Montana. 

Her current research examines several aspects of the interaction between Clark’s nutcrackers 

and whitebark pine, including: (1) timeframe of post-fire regeneration of whitebark pine, (2) 

detecting changes in nutcracker seed dispersal services as whitebark pine declines, and (3) 

the role of whitebark pine in vegetation dynamics at treeline. She received her B.A. and M.A. 

degrees in Zoology from the University of California at Los Angeles, and her Ph.D. in Biological 

Sciences from the University of California at Santa Barbara.

Carol A. Aubry is a Forest Geneticist with the U.S. Forest Service, Olympic National Forest in 

Olympia, Washington. She works on National Forests in the Pacific Northwest, and her work 

focuses on the protection and management of forest genetic resources, including (1) whitebark 

pine conservation and restoration, and (2) climate change adaptation strategies for forest tree 

species. She received her B.S. degree in Biology from the University of Hartford, Connecticut; 

her M.S. degree in Forestry from Yale School of Forestry and Environmental Studies; and her 

Ph.D. in Forest Genetics from Oregon State University, Corvallis.

Andrew D. Bower is a Forest Geneticist with the U.S. Forest Service, Olympic National 

Forest in Olympia, Washington. Andrew is the U.S. Forest Service Pacific Northwest Region 

Whitebark Pine Restoration Program Lead and has been involved in research on genetic issues 

with whitebark pine since 2001. He received his B.S. degree in Forestry from the University of 

California, Berkeley; his M.S. degree in Forest Science from Oregon State University; and his 

Ph.D. in Forest Sciences from the University of British Columbia.

Elizabeth M. Campbell is a Research Ecologist with the Pacific Forestry Centre, Canadian Forest 

Service in Victoria, British Columbia, Canada. She received her B.Sc.H. degree in Biology at 

Queen’s University Ontario; her M.Sc. degree in Biology from the University of Victoria, British 

Columbia; and her Ph.D. degree in Forest Ecology from the Université du Québec à Montréal 

Centre d’études de la forêt, Quebec. Her most recent work includes (1) a study of mountain 

pine beetle outbreaks in whitebark pine ecosystems, (2) describing, modeling, and projecting 

the potential impacts of biotic disturbances and climate change on boreal and temperate 

forest dynamics, and (3) incorporating the concepts of socio-ecological resilience into forest 

ecosystem management.

Cathy L. Cripps is an Associate Professor at Montana State University, Plant Sciences and 

Plant Pathology Department in Bozeman, Montana, and editor of the journal “Fungi in Forest 

Ecosystems.” She received her B.Sc. degree in Natural Resources from the University of 

Michigan and her M.S. degree and Ph.D. in Biology (Mycology) from Virginia Polytechnic 

Institute. Her research examines the mycorrhizal fungi associations with whitebark and limber 

pine. This includes discovery of the native fungi associated with the pines and inoculation of 

seedlings with native strains in the greenhouse.

Melissa B. Jenkins is a Silviculturist with the U.S. Forest Service, Flathead National Forest 

in Kalispell, Montana. She was the first Chair of the Greater Yellowstone Coordinating 

Committee, Whitebark Pine Subcommittee (2001-2002), and wrote the first whitebark pine 

restoration guidelines for the Greater Yellowstone Ecosystem in 2005. She received a B.S. 

degree in Ecosystem Management and Forestry from the State University of New York College 

of Environmental Science and Forestry in 1981 and has been a certified Silviculturist with the 

Forest Service since 1993.

Mary F. Mahalovich is a Regional Geneticist with the U.S. Forest Service, Northern, Rocky 

Mountain, Southwestern, and Intermountain Regions and based at the Forestry Sciences 

Laboratory in Moscow, Idaho. Her program management and research includes genecology; 

identifying, harnessing and deploying blister rust-resistant five-needle pines; and gene 
conservation. She received her B.S. degree in Forest Management from Northern Arizona 

University, Flagstaff; her M.S. degree in Forest Genetics from the University of California, 

Berkeley; and her Ph.D. in Forestry and Genetics from North Carolina State University, Raleigh.

Mary Manning is the Regional Vegetation Ecologist for the Northern Region of the U.S. Forest 

Service in Missoula, Montana. Her work is primarily in ecosystem classification and inventory 

and monitoring, with a special emphasis on non-forested vegetation and riparian/wetland 

ecosystems. She holds a B.S. degree in Natural Resources Management, with a minor in Range 

Management, from California Polytechnic State University, San Luis Obispo, and an M.S. degree 

in Rangeland Ecology from University of Nevada, Reno.

Shawn T. McKinney is the Assistant Unit Leader of the USGS Maine Cooperative Fish 

and Wildlife Research Unit, University of Maine, Orono. His research includes modeling 

community interactions across a range of whitebark pine habitat contexts, investigating Clark’s 

nutcracker spatial foraging patterns, and exploring the consequences of blister rust invasion on 

natural selection and the future adaptive ability of whitebark pine. He received a B.A. degree in 

Biology, History, and Environmental Studies from the University of Colorado, Boulder; an M.S. 

degree in Biology from the University of Colorado Denver; and a Ph.D. in Forest Ecology from 

the University of Montana, Missoula.

Michael P. Murray is a Forest Pathologist for the Ministry of Natural Resource Operations 

located at the Kootenay Lake Forestry Centre, in Nelson, British Columbia, Canada. His current 

research includes (1) whitebark pine dynamics and long-term monitoring, (2) climate-driven tree 

declines, (3) ameliorating forest root diseases, and (4) fire-pathology interactions. He received 

his B.A. degree in environmental science from the State University of New York, Plattsburgh; his 

M.S. degree in Natural Resources from Humboldt State University, Arcata, California; and his 

Ph.D. in Forest Ecology from the University of Idaho, Moscow.

Dana L. Perkins is a Forest Ecologist and Five-Needle Pine Coordinator for Idaho Bureau of Land 

Management. Her research involves development of whitebark pine tree-ring chronologies, 

study of historic and current mountain pine beetle epidemics and how they influence stand 

structure, and conservation and restoration of whitebark pine on lower treeline and mountain 

islands of BLM administered lands. She received her B.S. degree in Animal Science and Wildlife 

Biology from the University of New Hampshire, Durham; her M.S. degree in Renewable Natural 

Resources at the Laboratory of Tree Ring Research, University of Arizona, Tucson; and her Ph.D. 

in Ecology from Utah State University, Logan.

Dan P. Reinhart is a Supervisory Resource Management Specialist with Yellowstone National 

Park. He is the Park’s Representative with the Greater Yellowstone Coordinating Committee, 

Whitebark Pine Subcommittee and Terrestrial and Aquatic Invasive Species subcommittees. His 

research involves relationships of red squirrels and grizzly bears in whitebark pine habitats, 

Yellowstone grizzly bear food habits and habitat use, and participation in the monitoring and 

management of whitebark pine and wilderness in the Yellowstone Ecosystem.

Chris Ryan is the Wilderness, Wild and Scenic Rivers and Outfitter Guide Program Leader for 

the U.S. Forest Service Northern Region, Montana. She was the Forest Service Representative 

for the Arthur Carhart National Wilderness Training Center. Her 30-year Forest Service career 

has focused on wilderness management in areas such as Alpine Lakes in Washington State and 

the Boundary Waters Canoe Area Wilderness in Minnesota. Chris has a Bachelor’s degree in 

Resource Geography from Central Washington University in Ellensburg, Washington.

Anna W. Schoettle is a Research Plant Ecophysiologist with the U.S. Forest Service, Rocky 

Mountain Research Station in Fort Collins, Colorado. Her recent research on high-elevation 

five-needle pines includes regeneration requirements and population dynamics, resistance to 

white pine blister rust, gene conservation, and genetic structure studies toward the development 

of restoration strategies for impacted and threatened populations. She received both her B.S. 

degree in Biology and Botany and her M.S. degree in Plant Physiology from Cornell University, 

Ithaca, New York, and her Ph.D. in Physiological Ecology from the University of Wyoming, 

Laramie.

Cyndi M. Smith is an Ecosystem Scientist with Parks Canada at Waterton Lakes National Park 

in Waterton Park, Canada. She has undertaken research, monitoring, and restoration projects 

for both whitebark and limber pine. She obtained her B.E.Sc. degree from the University of 

Waterloo at Waterloo, Ontario, and her M.Sc. in Wildlife Ecology from Simon Fraser University 

at Burnaby, British Columbia. Cyndi has also been volunteer Associate Director of the 

Whitebark Pine Ecosystem Foundation since 2006.

iii
Acknowledgments

We are grateful to the members of the Whitebark Pine Ecosystem Foundation for 

providing material and reviews of this document. We also thank the following people 

who helped with the preparation of this report: Eva Karau, Signe Leirfallom, Aaron 

Sparks, and Don Helbrecht, of the U.S. Forest Service, Rocky Mountain Research 

Station, Missoula Fire Sciences Laboratory. We also thank Barry Bollenbacher and 

Bryan Donner, U.S. Forest Service, Northern Region, for extensive review of the 

several iterations of this publication.

Contents

1. Introduction...................................................................................................1

Structure of This Report..............................................................................................2

Whitebark Pine Ecology..............................................................................................2

Taxonomy ..............................................................................................................2

Distribution............................................................................................................3

Autecology.............................................................................................................4

Vegetation Community Characteristics ...................................................................5

Successional Dynamics..........................................................................................7

Pine-Bird Interactions.............................................................................................8

Squirrels...............................................................................................................11

Genetics...............................................................................................................13

Ectomycorrhizal Fungi..........................................................................................15

Fire Regimes.........................................................................................................17

Importance of Whitebark Pine..................................................................................20

Ecological Processes and Ecosystem Services.......................................................20

Recreation............................................................................................................20

Cultural Heritage..................................................................................................21

Timber..................................................................................................................21

Grizzly and Black Bears .......................................................................................22

Current Status...........................................................................................................23

Blister Rust ...........................................................................................................24

Mountain Pine Beetle...........................................................................................25

Fire Exclusion.......................................................................................................28

Climate Change....................................................................................................28

Extent of Decline..................................................................................................30

Other Whitebark Pine Issues ....................................................................................30

Whitebark Pine Restoration in Wilderness............................................................30

Conservation Efforts for Whitebark Pine................................................................33

2. Whitebark Pine Restoration Strategy ...........................................................35

The Strategy..............................................................................................................35

Important Restoration Concepts...............................................................................38

Historical Range and Variability............................................................................38

Physiological Constraints......................................................................................38

Assembly Rules....................................................................................................39

Proactive Approach ..............................................................................................39

Central Tenets of the Restoration Strategy..............................................................39

iv
3. National and Regional Direction .................................................................41

U.S. Forest Service....................................................................................................41

U.S. National Park Service........................................................................................42

Canadian Land Management Agencies......................................................................42

British Columbia .......................................................................................................42

Alberta......................................................................................................................43

4. Restoration By Spatial Scale.........................................................................45

Range-Wide Scale.....................................................................................................45

Assessments .........................................................................................................45

Restoration Actions...............................................................................................46

Management Concerns.........................................................................................47

A Range-Wide Prioritization for Whitebark Pine...................................................47

Regional Scale ..........................................................................................................50

Assessments .........................................................................................................50

Restoration Actions...............................................................................................50

The Northern, Rocky Mountain, and Intermountain Regions Genetic 

 Restoration Program for Whitebark Pine........................................................50

Management Concerns.........................................................................................52

The U.S. Forest Service Northern Region Restoration Strategy for 

 Whitebark Pine .............................................................................................52

The Pacific Northwest Region Restoration Strategy for Whitebark Pine .................55

The Greater Yellowstone Area Whitebark Pine Restoration Strategy.......................59

Forest Scale...............................................................................................................59

Assessments .........................................................................................................60

Restoration Actions...............................................................................................60

Management Concerns.........................................................................................61

Example: Implementation of the Greater Yellowstone Restoration 

 Decision Guidelines for the Caribou-Targhee National Forest........................61

Landscape Scale........................................................................................................63

Assessments .........................................................................................................64

Restoration Actions...............................................................................................67

Management Concerns.........................................................................................68

Example: Restoration Decision Guidelines for Watersheds on the 

 Caribou-Targhee National Forest ...................................................................70

Stand Scale ...............................................................................................................70

Assessments .........................................................................................................70

Restoration Actions...............................................................................................73

Management Concerns.........................................................................................77

Example ...............................................................................................................78

Tree Scale .................................................................................................................80

Assessments .........................................................................................................80

Restoration Actions...............................................................................................81

Management Concerns.........................................................................................82

Example ...............................................................................................................83

5. Implementation of Restoration Strategy.......................................................85

Decision Support Systems ....................................................................................86

6. Discussion....................................................................................................87

Future Research....................................................................................................88

Restoration Barriers and Challenges .....................................................................89

Limitations ...........................................................................................................89

7. The Range-Wide Perspective ........................................................................91

References.......................................................................................................92

Appendix A—Whitebark Pine Tree Improvement Program ............................107

v

USDA Forest Service RMRS-GTR-279. 2012. 1

Whitebark pine (Pinus albicaulis Engelm.) forests are 

declining throughout their range in North America because 

of the combined effects of historical and current mountain 

pine beetle (Dendroctonus ponderosae Hopkins Coleopteran: 

Curculionidae, Scotlytinae) outbreaks, fire exclusion management policies, and the introduced pathogen Cronartium 

ribicola, which causes the disease white pine blister rust 

in five-needle white pines (Keane and Arno 1993; Kendall 

and Keane 2001; Murray and Rasumussen 2003; Schwandt 

2006; Tomback and Achuff 2010) (Figure 1.1). The loss of 

this high-elevation tree species poses serious consequences 

for upper subalpine ecosystems, both in terms of the impacts 

on biodiversity and in losses of valuable ecosystem processes and services (Tomback and others 2001a; Tomback and 

Achuff 2010). The large, nutritious seeds produced by whitebark pine are an important food for birds and small mammals, 

as well as bears; whitebark pine communities provide habitat 

for many additional wildlife species; and rapid seed dispersal 

by Clark’s nutcrackers (Nucifraga columbiana Wilson) combined with hardy seedling growth results in early whitebark 

pine community development after fire and other disturbances (Hutchins 1994; Mattson and others 2001; Tomback 

and Kendall 2001; Tomback and others 2001c). Furthermore, 

whitebark pine seedlings survive on harsh, high-elevation 

droughty sites and may eventually act as nurse trees to less 

hardy conifers and vegetation (Callaway 1998; Callaway and 

others 1998; Tomback and others 2001c). At upper subalpine 

elevations, where it is common in many regions (Resler and 

Tomback 2008), whitebark pine helps regulate snow melt and 

reduce soil erosion (Farnes 1990). For these collective functions, whitebark pine is considered both a keystone species 

for promoting community diversity and a foundation species 

for promoting community stability (Ellison and others 2005; 

Tomback and others 2001a; Tomback and Achuff 2010). The 

loss of whitebark pine would potentially affect fire regimes, 

recreational experiences, and aesthetic perceptions (Keane 

and others 2002a; McCool and Freimund 2001; Tomback and 

others 2001a; Tomback and Achuff 2010).

Given limited budgets, personnel, and funding, the success of whitebark pine restoration efforts can be greatly 

enhanced by a coordinated strategy that integrates the latest 

scientific findings into a comprehensive plan for conserving 

the species. Since more than 90 percent of whitebark pine 

forests exist on public lands, including those managed by the 

U.S. Forest Service and National Park Service in the United 

States and by Provincial and Federal agencies in Canada, 

government land management agencies play key roles in ensuring the survival of this ecologically valuable tree species 

(Keane 2000; Tomback and Achuff 2010). If an inter-agency 

and even trans-boundary restoration strategy was developed 

that shared a common plan, infrastructure, and expertise, as 

well as other individual agency strengths for implementation, 

it could lead to more efficient use of scarce resources by integrating successful, cost-effective efforts for restoring this 

declining species.

1. Introduction

Figure 1.1. A declining 

whitebark pine stand 

in the northern Rocky 

Mountains of the 

United States (photo 

courtesy of Steve Arno).
2 USDA Forest Service RMRS-GTR-279. 2012.

The first step toward a comprehensive, range-wide restoration effort is to craft feasible strategies at multiple levels 

so landscapes can be prioritized for treatment and so restoration techniques can be designed to return the species to 

its historical prominence and function (Keane and others 

1996). Even in regions where whitebark pine losses are not 

yet great, such as the southern Sierra Nevada and interior 

Great Basin ranges, proactive strategies may help prevent or 

mitigate the severe declines experienced in, for example, the 

Northern Continental Divide Ecosystem (see Schoettle and 

Sniezko 2007; Smith and others 2008).

In this report, we describe a multi-scale strategy for restoring whitebark pine across its range in the western United 

States and Canada. It was compiled by researchers, land 

managers, and resource specialists to use as a reference for 

prioritizing, designing, and implementing successful whitebark pine restoration activities from stands to landscapes to 

National Forests to Regions, and ultimately, to the entire 

species’ range. This effort was based on a number of existing 

conservation plans and strategies (Aubry and Shoal 2008; 

Jenkins 2005; Keane and Arno 2001; Schwandt 2006; Shoal 

and others 2008; Wilson and Stuart-Smith 2001). The strategy has a set of principles with an associated array of possible 

actions to guide the design, planning, and implementation of 

restoration activities.

Structure of This Report

This report provides managers with the information needed to develop plans to restore whitebark pine. The first section 

presents basic ecological principles and knowledge that are 

important in understanding and implementing whitebark pine 

restoration strategies and treatments. Next, we present our 

general restoration strategy by defining our guiding principles, 

detailing restoration actions, and discussing the underlying 

concepts and ecological foundation of the rangewide strategy. 

We then discuss the major national and regional direction for 

the government agencies that manage whitebark pine in the 

context of this restoration strategy. Subsequently, we present 

information needed to implement the restoration strategy at 

six spatial scales. The entire range of whitebark pine in the 

United States and Canada is presented as the coarsest scale. 

Regional or province-wide assessments are the next finer 

scale, and finer yet is the forest scale that can be represented 

by a National Forest in the United States or national or provincial park in Canada. The landscape scale is nested within the 

forest or park scale, and it is usually defined by watersheds, 

ranger districts, or landforms. Landscapes are comprised of 

stands, the next smaller spatial scale, and it is at this scale 

where the majority of proactive restoration treatments and efforts are accomplished. The last scale is the tree. In landscape 

ecology, the next finer scale is used to provide the detail to the 

scale in question, while the next coarser scale provides the 

context in which to interpret that detail.

We also present a list of assessments that could be used 

for prioritizing and planning restoration treatments at a particular scale. Next, we list the tools and actions that promote 

and implement restoration treatments at that scale. Last, we 

present examples of restoration strategies designed specifically for a given scale using available data from various land 

management agencies. While the examples can be used to 

guide restoration activities, they may also be modified to develop alternative strategies that emphasize other important 

management concerns. We provide examples because it is 

impossible to construct standardized restoration strategies at 

finer scales due to the diversity of whitebark pine communities and their complex ecological processes, management 

issues, and public concerns. In other words, there is no “one 

size fits all” approach to developing landscape level restoration strategies. The examples may contain spatial data of 

mixed resolution and accuracy out of necessity because of 

the paucity of spatial data available to land management. In 

many cases, land managers are not able to wait for a consistent, area-wide data set before moving forward to develop 

their restoration strategy and implement treatments. In that 

case, the best available information should be used and then 

updated as more accurate information becomes available.

Whitebark Pine Ecology

The design and interpretation of any restoration effort 

demands a working knowledge of the autecology and synecology of species to be restored. This section contains a 

brief synopsis of whitebark pine ecology, emphasizing important concepts needed to understand the basic tenets of 

ecosystem restoration presented in this report. More detailed 

overviews are found in the contributed volume edited by 

Tomback and others (2001b), which may provide the most 

definitive source for background material on whitebark pine 

to date, and from Arno and Hoff (1990), which contains important silvicultural characteristics of whitebark pine.

Taxonomy

Pines are gymnosperms and classified in the class 

Pinopsida, order Pinales, and Division Coniferophyta (USDA 

NRCS 2009). Whitebark pine is further classified in the subgenus Strobus, a group known both as haploxylon pines for 

having one rather than two fibrovascular bundles per needle, 

and the soft pines for their light wood. Traditionally, whitebark pine was placed in section Strobus and in subsection 

Cembrae (Little and Critchfield 1969; Price and others 1998) 

as the only North American species of the “stone pine” group. 

The stone pines all have cones and seeds adapted to seed dispersal by birds—the “nutcrackers” (genus Nucifraga).

Recent genetic studies have suggested that Cembrae pines 

do not form a distinct group (Gernandt and others 2005). 

Gernandt and others (2005) recommended merging two fiveneedle white pine subsections—Strobi and Cembrae—into a 

new subsection Strobus placed within the new pine section 

Quinquefoliae. This arrangement suggests that the closest 

relatives of whitebark pine are not only the Cembrae pines 

but several other five-needle white pines (Syring and others 

2007).
USDA Forest Service RMRS-GTR-279. 2012. 3

Distribution

Whitebark pine has the largest and northern-most distribution of all five-needle white pines (Tomback and Achuff 

2010). It is found in the upper subalpine and treeline forests of 

the United States and Canada, including the northern Rocky 

Mountains, Great Basin, Sierra Nevada and Cascades, and 

northern coastal ranges (Arno and Hoff 1990; McCaughey 

and Schmidt 2001) (Figure 1.2). Its distribution is split into 

two broad sections: the western section includes the Sierra 

Nevada and Klamath Mountains of California and Cascade 

Mountains of Oregon, Washington, and British Columbia; 

and the Olympic Mountains of Washington and coastal 

ranges through the Bulkley Mountains of British Columbia 

to about 55 ̊ N latitude. The eastern section comprises the 

Rocky Mountains from the Salt River and Wind River ranges 

of western Wyoming north through the Greater Yellowstone 

Area (GYA), Idaho, Montana, Alberta and British Columbia. 

The northern-most whitebark pine stands in the Rocky 

Mountains occur north of Willmore Wilderness Provincial 

Park at about 54 ̊ N latitude. Whitebark pine also grows in 

the Great Basin ranges of northern and eastern Nevada and 

in the Blue and Wallowa Mountains of northeastern Oregon, 

as well as in other isolated, outlying stands. These two distributional regions are connected by scattered populations 

in northeastern Washington and southern British Columbia 

(Little and Critchfield 1969; Ogilvie 1990).

Whitebark pine forms extensive forests in the northern 

Rocky Mountains of the United States and it is also abundant 

on the eastern slope of the Cascades and Coast Ranges; however, it assumes a more patchy distribution at the northern end 

of its distribution in the Canadian Rockies and Coast Ranges 

of British Columbia (Arno and Hoff 1990). Whitebark pine 

grows on soils classified as Inceptisols (Typic Cryochrepts), 

in deeper volcanic ash deposits as Andic Cryochrepts or 

as Lithic Cryochrepts (USDA 1975). Among the Typic 

Cryochrepts these include the less, well-developed Entisols 

(Cryorthents in granitic substrates) and better developed 

Alfisols (Mollic and Typic Cryoboralfs), Inceptisols, and 

Mollisols (Argillic and Typic Cryoborolls) (Hansen-Bristow 

and others 1990). Some dry-sites in semiarid regions have 

a thick, dark surface horizon and are classified as Mollisols 

(Typic Cryoborolls), whereas soils that have a dark surface 

but low base saturation are classified as Typic Cryumbrepts 

(USDA 1975). Whitebark pine typically does not occur on 

limestone soils, except in wetter areas near and north of the 

Canadian border (reviewed in Weaver 2001). In the northern-most Canadian Rocky Mountains, whitebark pine grows 

exclusively on siliceous soils as opposed to limestone.

Figure 1.2. The range of whitebark 

pine, from Arno and Hoff (1990).
4 USDA Forest Service RMRS-GTR-279. 2012.

Autecology

Whitebark pine is a long-lived tree of moderate shade 

tolerance (Minore 1979) (Figure 1.3). It is common to 

find mature whitebark pine trees well over 400 years of 

age, especially on harsh growing sites (the oldest is more 

than 1,275 years) (Luckman and others 1984; Perkins and 

Swetnam 1996). Well-formed, thrifty individuals often have 

smooth, grey bark, especially in the tree crowns, which may 

appear white-ish in bright sunlight (Arno and Hoff 1990). 

Whitebark pine is slow growing in both height and diameter, 

and it rarely grows faster than most of its competitors except 

on the most severe sites (Arno and Hoff 1990).

Whitebark pine cones are purple in color, somewhat eggshaped, and grow at the tips of branches, primarily in the 

upper tree crown (Figure 1.4). These cones contain about 60 

large, wingless seeds depending on the magnitude of the cone 

crop (Forcella and Weaver 1980; Owens and others 2008; 

Weaver and Forcella 1986). Tomback (1982) reported a mean 

of 45 filled seeds per cone, whereas Weaver and Forcella 

(1986) reported 75 seeds per cone. These seeds are highly 

nutritious and are eaten by many insect, bird, and mammal 

species (Hutchins and Lanner 1982; Tomback and Kendall 

2001). High nutritive value in whitebark pine seeds is characterized by 21 percent protein (Lanner and Gilbert 1994) 

and fat content ranging from 28 percent (Robbins and others 

2006) to 52 percent (Lanner and Gilbert 1994). The cones 

remain closed after ripening because the scales lack principal 

fibrous tissues that pull them open (Harlow and others 1964). 

The seeds are relatively large, weighing on average 0.175 g 

each, with thick seed coats (McCaughey and Tomback 2001; 

Tomback and Linhart 1990) (Figure 1.5). Whitebark pine 

starts producing cones around 30 to 60 years of age, although 

trees must attain good canopy volume to have high cone 

production, usually at about 125 to 250 years of age (Arno 

and Hoff 1990; Krugman and Jenkinson 1974) (Figure 1.3). 

The frequency of large, cone crops within a given stand varies regionally by climate and population level, from yearly 

to every two or three to five years in many areas, although 

a few cones are produced within a stand nearly every year 

(Arno and Hoff 1990; Crone and others 2011; Krugman and 

Jenkinson 1974; Tomback and others 2001c).

Whitebark pine seeds are primarily dispersed and sown by 

Clark’s nutcracker, a bird related to crows, ravens, and jays 

(avian Family Corvidae) (see the “Pine-Bird Interactions” 

section). Whitebark pine has many morphological characteristics that are adaptations for its mutualistic relationship with Figure 1.3. Typical mature whitebark pine tree. Note the 

unique lyrate crown growth form.

Figure 1.4. Whitebark pine cones arrayed upward on the 

upper portions of whitebark pine tree crowns. Note the 

purple color and abundant sap.
USDA Forest Service RMRS-GTR-279. 2012. 5

the Clark’s nutcracker (Lanner 1982, 1996; Tomback 1983; 

Tomback and Linhart 1990). The closed cones ensure availability of seeds to nutcrackers. The seeds lack seed wings, 

which for most conifers serve to disperse seeds away from 

parent trees, slowing seed fall and lengthening seed dispersal 

distance (Figure 1.5). Winged seeds, however, are not useful 

with closed cones and would slow seed harvest for nutcrackers. When nutcrackers harvest winged seeds from other tree 

species, they clip or rub off each wing before placing the 

seed in their throat pouch. Thus, the wingless and large seeds 

make for efficient foraging. Although whitebark pine cone 

and seed traits are well adapted to this mutualism, widespread seed predation by pine squirrels (Tamiasciurus spp.) 

appears to select for heavier cone scales, thicker seed coats, 

and fewer seeds per cone, which reduces the efficiency of 

nutcrackers (Siepielski and Benkman 2007). Whitebark has 

a distinctive “candelabra” or lyrate growth form, with essentially a flat-topped, shrub-like canopy, which may increase 

canopy area for cone production while serving to display 

cones to the bird (Lanner 1982, 1996) (Figure 1.3). The 

cones usually grow perpendicular in their long axis from the 

tips of vertically oriented branches, providing easy access 

to the birds (Figure 1.4) (Lanner 1982; Tomback 1978). As 

a result, the cones are in plain sight from flying nutcracker’s 

view because they are purple, at the branch’s end, and at the 

top of the lyrate crown (Figure 1.3).

Vegetation Community Characteristics

Whitebark pine forests occur in two high mountain 

biophysical settings (Figure 1.6). On productive upper subalpine sites, whitebark pine is the major seral species that 

is replaced by the more shade-tolerant subalpine fir (Abies 

lasiocarpa [Hook.] Nutt.), Engelmann spruce (Picea engelmannii Parry ex. Engelm), or mountain hemlock (Tsuga 

mertensiana [Bong.] Carrière), depending on geographic 

region (Arno and Weaver 1990). These sites, referred to as 

“seral whitebark pine sites” in this report, support upright, 

closed-canopy forests in the upper subalpine lower transition 

to timberline, just above or overlapping with the elevational 

limit of the shade-intolerant lodgepole pine (Pinus contorta 

Douglas ex. Louden) (Figure 1.7) (Arno and Weaver 1990; 

Pfister and others 1977), and the two species can often share 

dominance. Other minor species found with whitebark pine 

on these sites are Douglas-fir (Pseudotsuga menziesii [Mirb.] 

Franco), limber pine (Pinus flexilis James), and alpine larch 

(Larix lyalli Parl) (Pfister and others 1977).

Whitebark pine can also successfully dominate highelevation settings (called “climax whitebark pine sites” in 

this report) on harsh sites in the upper subalpine forests and 

at treeline on relatively dry, cold slopes (Arno 1986; Arno 

and Weaver 1990; Steele and others 1983) (Figure 1.8). 

Other species, such as subalpine fir, spruce, and lodgepole 

pine, can occur on these sites but as scattered individuals 

with truncated growth form (Arno and Hoff 1990; Arno and 

Weaver 1990; Cooper and others 1991; Pfister and others 

1977). Alpine larch is often found on north-facing climax 

whitebark pine sites, often in association with sub-surface 

water (Arno and Habeck 1972). Whitebark pine can also 

occur as krummholz, elfin forests, clusters, groves, tree islands, and timber atolls in the alpine treeline ecotone (Arno 

and Hoff 1990; Tomback 1989) and as a minor seral in lower 

subalpine sites (Cooper and others 1991; Pfister and others 

1977).

Figure 1.5.

Whitebark pine 

seeds.
6 USDA Forest Service RMRS-GTR-279. 2012.

Figure 1.6. Elevational range of 

whitebark pine showing the 

two site types often associated 

with this species (from Keane 

2001b).

Figure 1.7. Mature whitebark 

pine in the later stages 

of development with the 

shade-tolerant subalpine 

fir becoming established 

in the overstory and 

dominant in the understory 

without disturbance. This 

successional replacement is 

typical on seral whitebark 

pine sites.

Figure 1.8. Old whitebark 

pine in the later stages of 

development on sites where 

whitebark pine is the indicated 

climax species. Subalpine 

fir can occur on these 

sites, but they are typically 

scattered individuals and do 

not successionally replace 

whitebark pine.
USDA Forest Service RMRS-GTR-279. 2012. 7

Whitebark pine forests often contain unique assemblages of plant species (Tomback and Kendall 2001). Most 

whitebark pine forests, especially the seral types, have 

low diversity in vascular plants (Forcella 1978), with the 

majority of understory plant cover composed of grouse 

whortleberry (Vaccinium scoparium Leiberg ex. Coville), 

huckleberry (Vaccinium membrenaceum Douglas ex. Torr.), 

menziesia (Menziesia ferruginea Sm.), Hitchcock’s smooth 

woodrush (Luzula glabrata [Hoppe ex. Rostk.] Desv. var. 

hitchcockii [Hämet-Ahti] Dorn), and common beargrass 

(Xerophyllum tenax [Pursh.] Nutt), with minor components 

of sedge (Carex spp. mostly Ross’ sedge (C. rossii Boott) 

and Geyer’s sedge (C. geyeri Boott), Pink Mountain-heath 

(Phyllodoce empertriformis [Sm.] D. Don), and broadleaf 

arnica (Arnica latifolia Bong), depending on geographical area, aspect, and elevation (Arno and Weaver 1990; 

Campbell 1998; Keane and Parsons 2010b; Pfister and others 1977). Other plants that may be occasional dominants 

include Idaho fescue (Festuca idahoensis Elmer), Parry’s 

rush (Juncus parryi Engelm.), and Wheeler bluegrass (Poa 

nervosa [Hook.] Vasey) (Arno and Weaver 1990; Aubry and 

others 2008a). In the Cascade range, whitebark pine can also 

be found with russet buffaloberry (Shepherdia canadensis [L.] Nutt.), kinnikinnick (Arctostaphylos uva-ursi [L.] 

Spreng.), and pipsissewa (Chimaphila umbellata [L.] W. 

Bartram). High-elevation climax stands of whitebark pine 

support many unique alpine, subalpine, and montane undergrowth species assemblages, some of which are only found 

in association with whitebark pine (Forcella 1978; Tomback 

and Kendall 2001). Forcella and Weaver (1977) found that 

whitebark pine forests had unexpectedly high biomass, but 

low productivity.

In Montana, the major habitat type where whitebark pine 

occurs as a major seral species is subalpine fir/woodrush 

habitat type in both the grouse whortleberry and Menziesia

phase (Pfister and others 1977). It also occurs as a major 

seral species on the rarer subalpine fir/Ribes montigium and 

subalpine fir/Clematis pseudoalpina habitat types found on 

the east side of the Continental Divide. Climax habitat types 

include whitebark, whitebark-subalpine fir, and subalpine 

fir-whitebark, but Pfister and others (1977) did not classify 

these treeline and upper subalpine sites in detail. Whitebark 

pine is also a major seral species in the Engelmann spruce/

grouse whortleberry and subalpine fir/arnica habitat types of 

western Wyoming (Steele and others 1983). In the Cascades, 

whitebark pine is found primarily in the parkland plant association type (PAG3201) (Aubry and others 2008a). Johnson 

(2004) identified several whitebark pine plant associations 

in the mountains between the Cascades and Rockies.

Successional Dynamics

As previously described, whitebark pine is eventually 

replaced, in the absence of fire, by the shade-tolerant subalpine fir, spruce, and mountain hemlock on the productive, 

seral whitebark pine sites (Arno and Hoff 1990; Campbell 

and Antos 2003; Keane 2001b) (Figure 1.7). It can take 

50 to 250 years for subalpine fir to replace whitebark pine 

in the overstory depending on the local environment and 

previous fire history (Arno and Hoff 1990; Keane 2001b). 

Successional processes vary considerably among and within 

regions (Campbell and Antos 2003; Keane 2001b); whitebark pine may occur as a minor to major seral component 

depending on biophysical settings, available seed sources, 

and disturbance type and severity.

Whitebark pine competes with lodgepole pine during early successional stages in the lower portions of its elevational 

range (Arno and others 1993; Mattson and Reinhart 1990). 

Lodgepole pine usually has the competitive advantage over 

whitebark pine when it establishes from seed after a standreplacing disturbance event because of its fast growth, 

serotiny, and copious seed production. Because lodgepole 

pine is less shade-tolerant than whitebark pine, it is more 

of an associate than a competitor in some whitebark pine 

forests, especially near treeline (Murray 1996). Kipfmueller 

and Kupfer (2005) described the complexity of successional development pathways after gradients of disturbance in 

central Idaho and western Montana. There are several successional pathway diagrams detailed in Keane (2001b) for 

use in modeling seral whitebark pine types, and we provide a 

simplified pathway for seral whitebark pine sites (Figure 1.9) 

to better understand the successional pathways in whitebark 

pine communities.

Figure 1.9. A generalized example of a successional pathway 

for a seral whitebark pine site. SH = mountain shrub, WP 

= whitebark pine, and SF = subalpine fir. Structural stage 

names: LCLH = low cover low height early succession 

stage, HCLH = high cover low height mid-seral stage, 

HCHH = high cover high height late succession stage, and 

LCHH = low cover high height disturbance maintained 

late succession stage (from Keane 2001b).
8 USDA Forest Service RMRS-GTR-279. 2012.

Pine-Bird Interactions

The Clark’s nutcracker (Figure 1.10) and whitebark pines 

have intertwined fates: they participate in a coevolved, mutualistic interaction (Lanner 1982; Tomback 1982, 1983; 

Tomback and Linhart 1990). Essentially, whitebark pine has 

evolved a nearly exclusive dependence on nutcrackers to disperse its large wingless seeds, and in turn, nutcrackers utilize 

fresh and stored whitebark pine seeds as an important food 

source. The key behavior that benefits the whitebark pine is 

the tendency of nutcrackers to bury thousands of whitebark 

pine seeds each year as food stores in small clusters or “seed 

caches” across diverse forest terrain (Hutchins and Lanner 

1982; Tomback 1982). These seed caches are retrieved 

by nutcrackers primarily in spring and summer months as 

an important food source for themselves and their young. 

However, not all seed caches may be recovered, particularly following a large cone crop. Snowmelt, spring rains, 

and summer showers stimulate seed germination, leading 

to whitebark pine regeneration (Tomback 1982; Tomback 

and others 2001c). Whereas whitebark pine depends nearly 

exclusively on nutcrackers, nutcrackers harvest and cache 

seeds of other large-seeded pines (see Tomback 1978, 

1998). This section describes the important interactions between the bird and pine based on information presented in 

Hutchins and Lanner (1982), Tomback (1978, 1982, 1983, 

1998, 2001, 2005), and Tomback and Linhart (1990).

There are two nutcracker species worldwide—the Clark’s 

nutcracker (Figure 1.10), which ranges throughout the higher 

mountains of the western United States and Canada, and the 

spotted or Eurasian nutcracker (Nucifraga caryocatactes), 

which is widely distributed across the higher mountains of 

Europe and north-central and eastern Asia (Tomback 1983). 

Both nutcrackers have co-evolved relationships with pines 

historically classified together as Cembrae or “stone pines” 

(see Taxonomy section) within the pine family Pinaceae, and 

the white pine (soft pine) subgenus Strobus. The Eurasian 

Cembrae pines include four species—Swiss stone pine 

(Pinus cembra), Siberian stone pine (P. sibirica), Korean 

pine (P. koraiensis), and Japanese stone pine (P. pumila). 

In North America, the sole Cembrae pine is whitebark pine. 

Fossil evidence indicates that the Cembrae pines may be the 

most recent pines to evolve (Tomback 2005). New genetic 

evidence suggests that these pines may not form a related 

(monophyletic) group, but rather evolved similar traits 

through convergence, perhaps selected in part by nutcracker 

seed dispersal (Gernandt and others 2005).

Nutcrackers belong to the avian family Corvidae (along 

with ravens, crows, and jays), whose members tend to hide 

food for future use and are distinguished by superior cognitive abilities (Tomback 2005; Tomback and Linhart 1990). 

Nutcrackers have specialized traits for foraging on conifer 

seeds: a bill that is long, sturdy, and pointed and used to remove the scales of closed cones, peck or crack open seeds, 

and store and recover seed caches; a well-developed spatial 

memory that enables each bird to retrieve thousands of seed 

caches each year; a functional incubation patch in males as 

well as in females (unlike most corvids), enabling males to 

incubate eggs or brood nestlings while females recover seed 

caches; an early nesting strategy, so that young are independent by late summer in time to cache their own seeds; and 

the sublingual pouch, a sac-like structure developed from 

the floor of the mouth with an opening under the tongue, 

which is used to transport conifer seeds and other nuts. For 

Clark’s nutcrackers, the filled pouch may hold as many as 

100 or more whitebark pine seeds.

Ancestors of the whitebark pine and the Clark’s nutcracker most likely evolved in Eurasia, and progenitor 

species reached North America via the Bering Strait land 

bridge during the Pleistocene (Lanner 1980, 1990; Tomback 

1983, 2001, 2005). Clark’s nutcracker rapidly expanded its 

range beyond that of whitebark pine, through the ranges of 

other large-seeded pines, such as limber, southwestern white 

(Pinus strobiformis), Colorado piñon (P. edulis), and singleleaf piñon (P. monophylla) (Tomback 1983; Tomback and 

others 2011). Seeds of these pines are dispersed by Clark’s 

nutcrackers as well, but importance of the interaction varies with the pine and geographic area. Nutcrackers also use 

seeds of other conifers, including ponderosa (P. ponderosa), 

Jeffrey (P. jeffreyi), the bristlecone (P. aristata and P. longaeva) pines, and Douglas-fir. In fact, the more widespread and 

frequent cone producers, such as ponderosa and Douglasfir, may represent stable, if less preferred, food sources for 

nutcrackers. Similarly, Eurasian nutcrackers use a variety 

of relatively large-seed pines and hazelnuts (Corylus avellena) beyond the Cembrae pines; and seed use also varies 

geographically (as an example, see Mattes 1984; Swanberg 

1956).

Figure 1.10. The Clark’s nutcracker. (Photo courtesy of Diana 

Tomback.)
USDA Forest Service RMRS-GTR-279. 2012. 9

Clark’s nutcracker life history is closely tied to Pinus spp. 

seed production (Tomback 1978, 1998). Nutcrackers forage 

on fresh pine seeds throughout the summer and fall and use 

their seed caches for winter and spring food, as well as for 

feeding nestlings (Mewaldt 1956; Vander Wall and Hutchins 

1983). The seed caches of a single nutcracker yield an estimated 1.8 to 5.0 times the energy required to survive the 

winter (Tomback 1982; Vander Wall and Hutchins 1983; 

Vander Wall and Balda 1977). Based on metabolic requirements, Tomback (1982) estimated that a local population of 

nutcrackers consumes about 55 percent of their stored seeds. 

Furthermore, nutcrackers are sensitive to rates of energy 

gain: they increase their foraging efficiency by selecting 

trees with ripe cones and higher cone densities, and cones 

with higher proportions of edible seeds (Tomback 1978; 

Tomback and Kramer 1980; Vander Wall and Hutchins 

1983; Vander Wall and Balda 1977).

Nutcrackers begin to harvest seeds as early as mid-July 

once cones are produced, removing pieces of unripe seeds 

from resinous cones, to feed themselves or their dependent 

juveniles (Tomback 1978). In the early summer, nutcrackers 

forage in subalpine forests and assess developing cone crops 

(Vander Wall and Hutchins 1983). This behavior presumably 

alerts birds to imminent seed shortages (Vander Wall and others 1981). Depending on the severity of cone crop failure, 

nutcrackers either emigrate regionally or irrupt synchronously from large geographic areas, such as the Sierra Nevada 

range, in search of food (Bock and Lepthien 1976; Davis and 

Williams 1957). The surviving nutcrackers apparently return 

to subalpine forests in the spring following mass migration 

and again assess the current year’s cone crop (Vander Wall 

and others 1981). Thus, the size, mortality, and reproductive 

rates of nutcracker populations are likely closely associated with cone production of their preferred Pinus species. 

In early summer the nutcrackers act as seed predators, and 

the lost seeds are a price the trees pay for seed dispersal 

services later in the summer. Throughout the summer, nutcrackers also retrieve whitebark pine seed caches made the 

previous year. By mid to late August, nutcrackers are able 

to harvest intact seeds with brown seed coats; this appears 

to be the stimulus for caching seeds. In a good cone crop 

year, nutcrackers continue to store whitebark pine seeds until 

October or November. When cone crops are low to moderate, 

nutcrackers are in a race for the seeds against pine squirrels—

the Douglas squirrel or chickaree (Tamiasciurus douglasii) of 

the Pacific ranges and widely distributed American red squirrel (T. hudsonicus)—that rapidly cut down cones as a winter 

food supply (see “Squirrels” section).

During fall, many nutcrackers move down to lower elevations or travel to other areas where they search for cones in 

other large-seeded conifers. Some birds spend the winter at 

lower elevations or moving up and down in elevation, retrieving caches and foraging in cones for remaining seeds, 

insects, and other foods. Nutcrackers begin courting as early 

as December and begin nest-building in March or earlier; 

young generally fledge in April or May (Tomback 1998). 

Most nutcrackers breed at mid-elevations, although some 

breed within the subalpine zone. Adults feed young seeds retrieved from caches and some insect material. From May to 

early July, depending on snowpack depth, nutcrackers return 

to subalpine elevations, many in family groups, and retrieve 

caches made in previous years.

Continued decreased cone production capacity within declining whitebark pine forests, coupled with the tendency of 

nutcrackers to emigrate when cone crops are small, could 

result in fewer seed dispersal events in many whitebark pine 

forests. This outcome is especially of concern because highmortality stands have lower cone abundance (McKinney 

and Tomback 2007), yet could harbor a higher frequency of 

rust-resistant alleles than similar stands with low mortality 

(Hoff and others 1994). Whether there exists a threshold of 

whitebark pine cone production necessary to elicit seed dispersal by nutcrackers, and whether the nutcracker-whitebark 

pine mutualism risks local and even regional disruption, are 

important questions for whitebark pine restoration planning. 

The following paragraphs are useful to address these questions and are excerpted from McKinney and others (2009).

The frequency of nutcracker occurrence in a whitebark 

pine forest is strongly associated with the number of available cones, and thus potential food-energy for the bird. The 

proportion of total observation hours with at least one Clark’s 

nutcracker sighting increased linearly with increasing whitebark pine cone production across 24 research sites in the 

U.S. Rocky Mountains (McKinney and Tomback 2007; 

McKinney and others 2009). Nutcrackers are unlikely to 

occur when cone production averages fewer than 130 cones 

ha-1. Furthermore, because nutcracker occurrence is strongly 

associated with cone production, it is also positively correlated with live whitebark pine basal area and negatively 

correlated with whitebark pine tree mortality. This suggests 

that measurable site variables that correlate to whitebark 

pine abundance, such as basal area and tree mortality, can be 

important indicators of cone production, and thus, bird occurrence. An often ignored component of cone production, 

also related to density, is an effective pollen cloud. When 

the number of reproductively mature conifers falls below 

4 trees ha-1, a sufficient pollen cloud is not present during female strobili receptivity for adequate fertilization, resulting 

in poor seed set or an increase in selfed seed (RobledoArnuncio and others 2004; Smith and others 1998) thereby 

limiting cone production available for seed caching.

Cone production is also a strong predictor of the probability of nutcracker seed dispersal. This relationship is 

consistent with what is known about nutcracker cognitive 

abilities as they relate to assessments of potential energy. 

It appears that by the time seed dispersal behavior begins 

(mid-August to early September), nutcrackers have decided whether or not to settle in an area, and this decision is 

largely determined by the magnitude of the existing cone 

crop. Moreover, there is a threshold of whitebark pine cone 

production below which there is a rapid decline in both 

the frequency of nutcracker occurrence and probability 

of seed dispersal. If cone production declines from 700 to 

300 cones ha-1, for example, the estimated likelihood of 
10 USDA Forest Service RMRS-GTR-279. 2012.

nutcracker occurrence declines from 0.4 to 0.1, and probability of seed dispersal declines from 0.7 to 0.3 (McKinney 

and others 2009).

Nutcrackers typically place from 1 to 15 seeds within 

a cache, although rare caches with more than 30 seeds 

have been observed; average cache sizes are 3 to 5 seeds 

(Hutchins and Lanner 1982; Tomback 1978, 1982). 

Nutcrackers select diverse microsites for caching, burying caches 1 to 3 cm under various substrates, such as 

forest litter, mineral soil, gravel, or pumice. Nutcrackers 

place many caches at the base of trees near the trunk or 

exposed roots and these microsites tend to experience early 

snowmelt. Nutcrackers also cache next to fallen trees and 

rocks, in fallen trees, in open terrain, among plants, on 

rocky ledges, and in rock fissures. They place some of their 

caches in trees, tucking seeds in cracks, holes, and under 

the bark (Lorenz and others 2008; Tomback 1978). They 

will also cache whitebark pine seeds at and above treeline, 

among patches of conifers and in small depressions in open 

areas. Whitebark pine seeds may be cached near source 

trees or transported 32 km or farther, often to higher or 

to lower elevations, where whitebark pine cannot grow 

as well (Lorenz and others 2011; Tomback 1978). Studies 

have indicated that nutcrackers may transport seeds long 

distances, (piñon pine, for example, is dispersed 22 km; 

Vander Wall and Balda 1977). Nutcrackers appear to cache 

across a variety of terrain within their home range but also 

within communal storage areas, which are steep and southfacing slopes used by a local population of nutcrackers for 

caching. These slopes tend to be within 3 to 4 km of source 

trees.

Estimates of the numbers of whitebark pine seeds stored 

per bird within one season have been based on different 

assumptions and for different geographic regions, but vary 

from 35,000 seeds in about 9500 caches in the eastern 

Sierra Nevada, California (Tomback 1982), to 98,000 seeds 

in 30,600 caches in the Absaroka Mountains, Wyoming 

(Hutchins and Lanner 1982). With these estimates, a 

population of 25 nutcrackers would store from 95,000 to 

750,000 caches (Tomback 1982). Seeds in unclaimed nutcracker caches germinate following snow melt and spring 

and summer rains, resulting in single seedlings or clusters 

of seedlings appearing throughout a caching area (Tomback 

1982) (Figure 1.11). However, the nutcracker caching 

mode of seed dispersal has exerted selection pressure on 

both the seed structure and timing of germination in whitebark pine, as well as in other Cembrae pines (McCaughey 

1993; McCaughey and McDonald 1993; Tillman-Sutela 

and others 2008). Both planting and natural experiments 

indicate that whitebark pine seeds typically require two 

or more winter dormancy cycles before they germinate 

(McCaughey 1993; Tomback and others 2001c). Therefore, 

seeds often do not germinate within the next growing 

season following seed caching, but rather two or more 

growing seasons later, and germination appears to correspond to higher moisture availability. Delayed germination 

may result from the short growing season in the subalpine 

zone coupled with the fact that nutcrackers are caching a 

proportion of seeds before seed development is complete, 

resulting in underdeveloped embryos (Tomback and others 2001c). Seeds may also have physiological resistance 

to germination until available moisture is sufficient, which 

may be an adaptation to increase survival.

Figure 1.11. A cluster of whitebark pine seedlings that 

germinated from unretrieved seed cached by the Clark’s 

nutcracker.
USDA Forest Service RMRS-GTR-279. 2012. 11

Seed dispersal by nutcrackers has diverse influences on 

the ecology of whitebark pine. For example, the sites selected 

by nutcrackers for seed caching, along with the environmental suitability of these sites for seed germination and 

seedling survival, determine where whitebark pine occurs on 

the landscape (Tomback 1983, 2001, 2005). The tendency 

of nutcrackers to cache seeds below and above the current 

elevational distribution of whitebark pine enables whitebark pine to respond rapidly to climate cooling or warming 

with changes in elevational and even latitudinal distribution. 

This influence is particularly important now, with climate 

warming predicted to cause an upward and northward shift 

in whitebark pine distribution (Tomback 2005; Tomback 

and Achuff 2010). Secondly, seed dispersal by nutcrackers 

is responsible for the genetic population structure of whitebark pine at several spatial scales (Tomback 2005). At the 

local level, the seed caching mode of seed dispersal results 

in a unique fine-scale genetic population structure. Because 

two or more whitebark pine seeds are often cached together, 

several seedlings from a cache may survive and produce a 

“tree cluster” growth form. This growth form appears to be 

a single tree with multiple stems that are tightly clustered or 

fused at the base or part way up the stem. Genetic studies 

confirm that most of these tree cluster growth forms contain 

distinct individuals, each arising from a different seed within a cache. Also, because nutcrackers harvest from several 

seeds to an entire pouch-load of seeds from a single tree, 

there is a high probability that the seeds within a cache are 

genetically related (Rogers and others 1999; Tomback and 

Linhart 1990; Tomback 2001, 2005). Finally, within a given 

area, nutcrackers cache at random with respect to caches already present, and with seeds from different source trees. 

Consequently, the seedlings among neighboring caches 

are usually unrelated, resulting in a random genetic pattern 

among clusters.

At the landscape and regional scale, we see the influence 

of nutcracker caching behavior as well on genetic population structure (Dimmick 1993; Hutchins and Lanner 1982; 

Tomback 1978). As mentioned, nutcrackers can disperse 

seeds over distances that are far greater than the mean distances traveled by wind-dispersed conifer seeds, and can 

easily move seeds over mountain passes and into adjacent 

drainages. Wind blows pollen over long distances as well. 

Consequently, researchers have found very little genetic 

differentiation among whitebark pine populations at both 

landscape and regional scales (Bower and others 2011; 

Bruederle and others 1998; Jørgensen and Hamrick 1997; 

Mahalovich and Hipkins 2011; Rogers and others 1999); 

this genetic differentiation is lower than found for most 

wind-dispersed conifer seeds (Bruedele and others 2001; 

Rogers and others 1999) or animal-ingested seeds (Hamrick 

and others 1992).

Squirrels

The North American red squirrel (Tamiasciurus hudsonicus) is a highly efficient, voracious consumer of conifer 

seeds (Figure 1.12). Squirrels cut down conifer cones using 

their sharp teeth and strong temporal muscles and either eat 

seeds in situ or carry cones off to be stored for later use. 

Cone storage sites, called middens, are often large, conspicuous piles (for example, 1 m height by 10 m diameter) of 

cone debris that deeply cover the ground to the exclusion 

of living plants (Finley 1969) (Figure 1.13). Red squirrels 

are highly territorial, with the midden serving as the territorial hub, and home ranges are often small (less than 5 

ha). They are thus central place foragers (Elliot 1974; Smith 

1968)—a behavior describing the need to return to a particular place to hoard (consume or feed offspring) food. Due 

to their high foraging efficiency and central-place foraging 

lifestyle, red squirrels can greatly diminish cone crops at a 

local level (sometimes near 100 percent, Flyger and Gates 

1982) and exert tremendous selection pressure on conifer 

cone morphology at a population level (Benkman and others 

1984; Smith 1970). Moreover, red squirrels preferentially 

select tree species based on cone energy content (Smith 

1970), foraging first on the highest energy species before 

moving on to the next highest energy species (Hutchins and 

Lanner 1982; Smith 1970). This adaptation is significant to 

the fate of whitebark pine because it has the greatest cone 

energy content of all sympatric species in U.S. northern 

Figure 1.12. The red squirrel competes with the Clark’s 

nutcracker for whitebark pine seeds.
12 USDA Forest Service RMRS-GTR-279. 2012.

Rocky Mountain upper subalpine forests (whitebark pine 

= 27.7 Kcal cone-1, next highest subalpine fir = 15.7 Kcal 

cone-1) (Smith 1970; Tomback 1982). Indeed, red squirrels 

are the primary pre-dispersal seed predator of whitebark 

pine in the Rocky Mountains, taking more than 80 percent 

of the cone crop in some areas (Hutchins and Lanner 1982; 

McKinney and Tomback 2007).

Squirrels climb whitebark pine trees and rip or bite cones 

off the branches and let them drop to the ground (Finley 

1969). The fallen cones are then collected and placed in 

middens for winter storage (Reinhart and Mattson 1990) 

(Figure 1.13). These middens can be in depressions on the 

ground, in hollowed logs, and around tree bases. Whitebark 

pine regeneration is rarely successful from middens because 

of (1) the deep depths that the squirrels store cones, (2) the 

high amounts of Fusarium spp. fungus in the discarded cone 

scales, and (3) the high use of cones by bears and other rodents. Optimum squirrel habitat within the whitebark pine 

zone consists of habitats with high overstory-basal area and 

high species diversity on moderate slopes (Podruzny and 

others 1999). Optimum stand characteristics that favor red 

squirrels are when total stand basal area is greater than 40 m2

ha-1 and whitebark basal area represents 15 to 50 percent of 

the total basal area (Mattson 2000).

Although red squirrels appear to favor whitebark pine 

seeds, their residence in whitebark pine forests (or any other 

type) is dependent on forest structure and tree species composition (Fisher and Bradbury 2006; Mattson and Reinhart 

1997). Squirrels need to store enough cones to survive long 

boreal winters (Steele 1998); over time, this requirement 

is best met in mature mixed conifer species forests (often 

those with high basal area and tree species diversity) and 

not frequently met in forests where whitebark pine makes up 

greater than 50 percent of stand basal area (McKinney and 

Fiedler 2010). Squirrel energy requirements may be met in 

whitebark pine dominant stands during high cone production 

years, but cone production of necessary quantities usually 

does not occur with enough frequency to maintain resident 

populations of squirrels. Therefore, red squirrel occurrence 

in dominant whitebark pine stands is often transient, with a 

higher number of cones eaten in situ and a lower number of 

active middens relative to mixed species forests (Mattson 

and Reinhart 1997; McKinney and Fiedler 2010). Thus, for 

the squirrel, a trade-off may exist between selection at the 

tree level (whitebark pine for its high energy seeds) and at 

the stand level (an annual cone crop large enough for population maintenance) (McKinney and Fiedler 2010).

Cone predation within a given forest is directly associated with red squirrel residential status. For example, in U.S. 

central and northern Rocky Mountain forests, the proportion 

of total squirrel detections comprised of active middens was 

positively and significantly correlated with whitebark pine 

pre-dispersal cone predation (r = 0.65, p<0.05) (McKinney 

and Fiedler 2010). As cone production increases, squirrel 

predation also increases at both tree and stand levels; however, the strength of the relationship between production and 

consumption is dependent on the degree to which whitebark 

pine is a dominant component of the stand (McKinney and 

Fiedler 2010; McKinney and Tomback 2007). Pre-dispersal 

cone predation decreases with increasing proportion of total 

stand basal area comprised of whitebark pine. Therefore, as 

whitebark pine becomes more of a dominant component of 

canopy structure, conditions for squirrel residence become 

less favorable and cone predation declines.

In summary, whitebark pine-dominated forests, such as 

climax forests, are sub-optimal squirrel habitat. Conversely, 

red squirrels thrive in mixed species forests containing 

whitebark pine. The reason for the disparity between the two 

forest types in red squirrel residential status appears due to a 

higher degree of uncertainty in annual cone crops (Reinhart 

Figure 1.13. A squirrel midden 

site consisting of cached 

whitebark pine cones.
USDA Forest Service RMRS-GTR-279. 2012. 13

and Mattson 1990). For example, during a three year study, 

average year-to-year differences in whitebark pine cone production within sites was 87 percent relative to mean cone 

production (the absolute difference between two years divided by the mean of the years, multiplied by 100) (McKinney 

and Fiedler 2010). Higher uncertainty appears to be directly 

related to lower diversity of conifer species because of the 

greater chance of cone crop failure. Squirrels still, however, 

prefer whitebark pine cones to the cones of sympatric conifers and will disperse into pure to nearly pure whitebark 

pine stands to harvest cones, especially after disturbances 

such as wildfire (McKinney and Fiedler 2010; McKinney 

and Tomback 2007). Whitebark pine-dominant stands (for 

example, stands with greater than 50 percent of total basal 

area comprised of whitebark pine) will have a larger proportion of their annual initial cone crop available for seed 

dispersal relative to mixed conifer species stands.

Genetics

A key component of any whitebark pine restoration program is the planting of rust-resistant seeds or seedlings for 

reforestation (Keane and Parsons 2010b; Mahalovich and 

Dickerson 2004; Mahalovich and others 2006). However, 

the wide movement of seeds away from the source of collection increases the risk of maladaptation, which could lead to 

reduced growth and survival (Campbell 1979; Mahalovich 

2012). Seed transfer should be guided by natural levels of 

genetic variation and local adaptation in quantitative traits 

specific to the species in question (Morgenstern 1996; Hufford 

and Mazer 2003; McKay and others 2005 ) Understanding 

genetic structure is also necessary for predicting the possible 

effects of climate change (St. Clair and others 2005). Current 

predictions of future climates may complicate seed transfer. 

A diverse mixture of seed sources can balance suitability of 

individuals to current and future environments (Bower and 

Aitken 2008). An individual’s genetic makeup, in interaction 

with its environment, determines the amount of variation in 

measurable characters (quantitative traits) such as growth, 

survival, tolerance to biotic and abiotic stress, and disease 

resistance. Genetic variation is quite important because it 

provides the raw material for adaptation to new environments. The amount and structure of genetic variation within 

a population are influenced by many factors including gene 

flow, mutation, genetic drift, and selection (Frankham and 

others 2002). Knowledge of a species’ genetic structure is 

essential to ensure that management activities do not adversely affect the amount and patterns of genetic diversity.

Genetic variation and population structure may be assessed with two types of traits: (1) molecular markers 

controlled by a single gene and (2) quantitative traits controlled by many gene loci. Molecular markers include 

allozymes, which differ in amino acid sequence and can be 

visualized with gel electrophoresis, and differences in DNA 

(Deoxyribonucleic acid) sequence fragments. DNA fragments that are used as markers are often in sections of DNA 

that do not control a specific gene (non-coding) and therefore 

are not acted upon by natural selection (they are selectively 

neutral). Thus, while they are useful to distinguish distinct 

breeding groups, the genetic differences do not imply differences in adaptation (Reed and Frankham 2001). To examine 

potential adaptive variation other methods must be used.

Genecology is the study of genetic variation and its relationship to environmental variation. Differences in seed 

sources grown in a common environment are thereby attributed to genetics, and when this genetic variation is correlated 

with the physiographic (for example, latitude, longitude, 

elevation, and distance from the coast) and climatic variables (temperature, rainfall, and growing season) of the 

seed source location, it may indicate a trait has responded 

to selection and has adaptive value. The amount of differentiation among seed sources facilitates ascribing a species’ 

adaptive strategy from low (generalist), moderate (intermediate) to high (specialist). A direct management application 

of these types of studies is the development of seed transfer 

guidelines. Quantitative traits, such as growth, survival, biomass production, and biotic and abiotic stress tolerance, are 

generally considered better indicators of adaptation and are 

measured on trees growing in the field (usually in seedling 

common gardens or field test sites). In these types of tests, 

individuals from multiple geographic origins are grown 

together in the same environment. The organization of genetic differences among populations (genetic structure) of 

a species can be estimated by using both molecular markers 

and quantitative traits. Since quantitative traits are usually 

subject to the effects of natural selection, while molecular 

markers are usually not, the difference between these measures of genetic structure is often taken as evidence of natural 

selection resulting in local adaptation (Merila and Crnokrak 

2001; Spitze 1993).

Genetic variation within whitebark pine has been assessed in several studies using neutral molecular markers at 

scales ranging from a single watershed to most of its range, 

and whitebark pine appears to have lower levels of genetic 

differences among populations than other wind-dispersed 

pines. Several allozyme studies assessing genetic variation 

and differentiation found that levels of whitebark pine genetic diversity (expected heterozygosity) were within the range 

of other stone pines (Pinus subsection Cembrae: Politov and 

others 1992; Jorgensen and Hamrick 1997), but somewhat 

below that of wind-dispersed pines in the subgenus Strobus

(Bruederle and others 2001; Ledig 1998). Only about 4.9 

percent of the measured genetic variation in allozymes is 

due to genetic differences among populations, while the 

vast majority of variation resides within populations (Bower 

and others 2011; Bruederle and others 1998; Jørgensen and 

Hamrick 1997; Krawkowski and others 2003; Mahalovich 

and Hipkins 2011; Stuart-Smith 1998; Yandell 1992). This 

estimate of population differentiation is slightly higher than 

the mean for the four other Cembrae pines (4.6 percent) 

(Belokon and others 2005; Goncharenko and others 1993a, 

1993b; Krutovskii and others 1995; Potenko and Velikov 

1998, 2001; Tani and others 1996) and is consistent with 

wind-dispersed pines that typically have less than 10 percent 
14 USDA Forest Service RMRS-GTR-279. 2012.

of their genetic diversity among populations (Ledig 1998). 

Thus, populations of bird-dispersed pines do not appear to 

be strongly differentiated using putatively neutral molecular markers. Additionally, Jorgensen and Hamrick (1997) 

reported that populations that have colonized areas covered 

by Pleistocene glaciers were more differentiated than populations from non-glaciated areas. Populations in the northern 

(western British Columbia), eastern (Rocky Mountains), 

and southern (Oregon and California) regions of the species’ range are differentiated for monoterpenes (Zavarin and 

others 1991), allozymes (Yandell 1992), and organelle DNA 

(Richardson and others, 2002b).

The population genetic structure of whitebark pine is 

strongly affected by seed dispersal by Clark’s nutcracker. In 

general, based on molecular markers, whitebark pine appears 

to have lower levels of genetic differences among stands than 

most wind-dispersed pines. Caching of seeds by the Clark’s 

nutcracker was first implicated as the cause of the “tree cluster” or multi-stemmed growth form of whitebark pine in 

the early 1980s (Lanner 1982; Tomback 1982). Linhart and 

Tomback (1985) and Furnier and others (1987) found more 

than two genetically distinct individuals in the majority of 

multi-stemmed clumps, indicating that these stems had arisen 

from different seeds. Furnier and others (1987) also found that 

individual stems within clumps were often related, presumably because multiple seeds from the same tree or even the 

same cone were cached together. While stems within clumps 

were often related, there was little genetic structure among 

clumps, with the distance among them not correlated to how 

closely they were related. These results were supported by 

Rogers and others (1999), who found little genetic differentiation among watersheds, but also found that differentiation 

between elevations was moderate and differentiation within 

thickets of clumps was strong. Individuals within krummholz 

thickets often shared one or both parents, most likely because 

of the seed-caching behavior of the Clark’s nutcracker.

In whitebark pine populations, inbreeding depression 

may result from the tendency of whitebark pine stems to 

grow in clusters of clumps of genetically related individuals 

(Figure 1.11). Inbreeding depression and reduced fitness typically accompany an increase in homozygosity in progeny that 

comes from matings among relatives. From two populations 

in southern British Columbia, Krakowski and others (2003) 

reported an inbreeding rate for whitebark pine of 27 percent, 

presumably as a result of the growth structure of clumps of 

related individuals. This rate is considerably higher than for 

most wind-pollinated conifers, which typically have inbreeding rates of less than 10 percent (Ledig 1998). Bower and 

Aitken (2007) confirmed the inbreeding rate for these populations; however, they reported that inbreeding rates ranged 

from 2 to 12 percent from five populations in Oregon and 

Montana. The areas where the Oregon and Montana populations were sampled were not glaciated at the last glacial 

maximum, so the higher level of inbreeding in the southern 

British Columbia populations may reflect postglacial colonization patterns and processes. Bower and Aitken (2007) also 

reported little evidence of inbreeding on quantitative traits, 

with only one trait (biomass) in only one geographic region 

(southern British Columbia) showing a reduction that was 

correlated with the level of inbreeding. Therefore, relative to 

other threats faced by whitebark pine, inbreeding depression 

does not appear to be of great concern.

DNA markers from mitochondria and chloroplasts 

have also been used to study population genetic structure 

and biogeographic patterns of whitebark pine (Richardson 

and others 2002a). The DNA of these organelles is inherited maternally and paternally, respectively. Microsatellites 

(tandemly repeated DNA sequences) were used to assess 

genetic structure from 41 populations that covered most of 

the species’ range. Richardson and others (2002a) found that 

whitebark pine populations clustered by genetic similarity 

into three main groups: Sierra Nevada, Yellowstone, and all 

others (northern Cascades, northern Idaho, central Idaho, 

and southern Oregon); the level of genetic differentiation 

(0.046) among these three groups was similar to the values 

reported from allozyme studies. Based on the geographic 

patterns observed with the DNA markers, the authors inferred three glacial refugia—southern Oregon, central Idaho, 

and the Yellowstone area—with a subsequent post-glacial 

colonization route northward into Canada and a secondary 

contact zone between the Oregon and Idaho populations in 

the Washington Cascades. This probable secondary contact 

zone was confirmed with a finer-scale sampling study at the 

location of the proposed contact zone (Richardson and others 2002b). This contact zone is supported by results of a 

recent molecular marker study of Oregon and Washington 

populations, which separated “northern” and “southern” 

populations here, but also showed that Olympic peninsula 

populations are genetically distinct from all other populations (Bower and others, unpublished data).

A few studies have assessed genetic variation in quantitative traits such as cold hardiness, growth, phenology, 

stem form, and disease resistance. Mahalovich and others 

(2006) found significant differences among sources for late 

winter cold injury (cold hardiness), survival, height growth 

and blister rust resistance, with most of the differentiation 

attributed to sources from the GYA. Cold hardiness and rust 

resistance show opposite geographic patterns, with sources 

in the northwest having higher rust resistance and lower 

cold hardiness, and southeastern sources having lower rust 

resistance and higher cold hardiness. Most trait correlations 

are favorable, and unfavorable correlations with cold hardiness can be managed through zoning, a restricted selection 

index (Mahalovich 2012; Mahalovich and others 2006), or 

site-specific planting prescriptions to avoid frost pockets and 

swales (McCaughey and others 2009). Family heritabilities 

for survival, height, cold hardiness, and blister rust resistance are moderate to high (h2

F = 0.68-0.99). Gentle clines in 

elevation for height and rust resistance and moderate clines 

in cold hardiness characterize whitebark pine as having a 

generalist to intermediate adaptive strategy in the Northern 

Rockies (Mahalovich 2012). Moreover, adaptation to heterogeneous environments does not appear to be as strongly 

related to phenotypic plasticity as in western white pine.
USDA Forest Service RMRS-GTR-279. 2012. 15

Until whitebark pine seed orchards reach reproductive 

maturity, reforestation planting should be met with cone 

collections from rust-resistant areas, as identified by their 

progeny in rust screening trials. Similar to other conifers in 

the northern Rockies, whitebark pine is likely to have different adaptive strategies and response to geo-climatic traits 

in various parts of the species range; therefore, seed transfer is not approached from a “one size fits all” perspective. 

Both population structure in molecular traits (Mahalovich 

and Hipkins 2011) and patterns of genetic variation in key 

adaptive traits (Mahalovich 2012; Mahalovich and others 

2006) characterize seed transfer in the Inland West (Idaho, 

Montana, Nevada and Wyoming) as follows:

• Greographically broad (±1.85° latitude, ±2.15° longitude) characterized by five seed zones.

• Within seed zones, proven rust-resistant seed sources are 

top priority, followed by phenotypically rust-resistant 

sources waiting genetic testing in rust screening trials.

• Where cold hardiness is problematic (McCaughey and 

others 2009), transfer is further restricted to ±245 m in 

elevation.

• Rather than transferring rust-resistant sources large 

distances across zones and traversing as much as 1600 m 

in elevation, risking maladaptation or outright mortality, 

correlation breakers (sources exhibiting both rust 

resistance and cold hardiness) should be utilized within 

a seed zone (Mahalovich and others 2006).

• In anticipation of climate change, transfer of rustresistant seed sources should be unidirectional from 

colder (northerly latitude, higher elevations, or both) to 

milder climates within the local temperature envelope 

and seed zone.

Bower and Aitken (2006) found that the level of cold hardiness varies throughout the year from below -70 o

C in the 

winter to -9 oC in the summer. Acclimation and de-acclimation to cold often occurs rapidly over a period of two to three 

weeks in the fall and spring, respectively; however, even 

during the period of active shoot elongation, whitebark pine 

shows greater hardiness to cold than most conifers (see also 

Mahalovich and others 2006). Geographic regions differed 

in cold hardiness in all seasons except in winter. Interior and 

northern sources were higher and California was lower in 

hardiness in the fall, with opposite patterns in the spring. 

Bower and Aitken (2008) proposed seed transfer guidelines 

based on population variation in quantitative traits:

• Seeds can be moved without substantial risk of maladaptation from seed collection site to planting sites differing 

up to 1.9 oC in mean temperature of the coldest month in 

the northern region, and 1.0 oC in the Rocky Mountain 

region; however, maladaptation could still occur if the 

seeds are not from a rust-resistant source.

• Differences in mean temperature of the coldest month 

correspond to approximately 4.6° latitude or 505 km 

for the northern region, and 320 m in elevation in the 

Rocky Mountain region based on a 20 percent risk of 

maladaptation; however, late winter cold hardiness in a 

larger representative sample from the Rocky Mountain 

region (Mahalovich 2012) restricts elevation transfers to 

only 245 m.

• Where blister rust resistance has been demonstrated 

in rust screenings, it may be necessary to move seeds 

farther to take advantage of this resistance. However, 

this increases the risk of maladaptation, which must be 

weighed against the need for restoration (see previous 

discussion on correlation breakers).

• In the southern region, the lack of correspondence 

between the seedling and climatic traits means that 

seeds can be freely moved within this region; however, 

movement between mountain ranges is to be avoided.

• Except for the Inland West populations, seed movement 

should be unidirectional from milder to colder climates 

within the local temperature envelope to account for 

predicted warming due to climate change.

Ectomycorrhizal Fungi

Whitebark pine, like other pines, requires ectomycorrhizal (ECM) fungi for survival in nature (Read 1998; Mohatt 

and others 2008); this beneficial biotic factor should be 

taken into account in management strategies to help ensure 

establishment, maintenance, and conservation of this pine 

species.

There are 7000 to 10,000 species of ECM fungi associated with trees and woody shrubs (Taylor and Alexander 

2005). Whitebark pine hosts only a small subset currently 

assessed at fewer than 50 species (Mohatt and others 2008; 

Molina and Trappe 1994). These ECM fungal species can 

be grouped ecologically into (1) generalists that associate 

with many trees such as pines, spruce, and fir (Amphinema, 

Cenococcum, Piloderma, and thelephoroid fungi); (2) associates of high-elevation western conifers (Cortinarius, 

Russula, Lactarius, Tricholoma, Hygrophorus, and fungi 

associated with snowbanks); and (3) specialists specific 

for pines such as five-needle pines or stone pines (Suillus, 

Rhizopogon, and Chroogomphus) (Cripps and Antibus 

2010). The last group (the suilloids) has a long history of 

association with stone pines on a hemispheric scale (Wu and 

others 2000). Suilloid fungi are host-specific on some level; 

some are restricted to pines, five-needle pines, or stone pines 

(Grubisha and others 2002; Moser 2004). Several host-specific suilloid fungi occur with whitebark pine, and there is a 

risk that this important group of fungi will decline in western North America as whitebark pine declines (Mohatt and 

others 2008). ECM fungi are successional; some occur with 

young trees and others with mature trees. However, suilloid 

fungi appear to span all tree ages.

The conservation of species and genetic diversity in 

ECM fungi are important because these fungi (as species or 

strains) vary in host specificity; soil preference; host age requirements; dispersal strategies; ability to enhance nitrogen 
16 USDA Forest Service RMRS-GTR-279. 2012.

(N) or phosphorus (P) uptake; types of N and P accessed; 

and protective abilities against pathogens, drought, heavy 

metals, and soil grazers (Tedersoo and others 2009). The 

ECM community as a whole provides a vast array of benefits 

to trees and forests.

Negative Impacts on ECM Fungi

Practices and impacts potentially threatening to the maintenance of ECM diversity in the soil include tree cutting, soil 

removal, mechanical disturbance, soil compaction, erosion, 

mining activities, liming, N-deposition, fertilization, highseverity fire, reduction of tree age diversity, and promotion 

of certain grasses. Additional detrimental effects may result from removal of certain understory or reservoir plants, 

woody debris, nurse trees, and other microsite components

(reviewed in Wiensczk and others 2002). In general, these 

practices should be minimized to maintain high ECM fungal 

diversity in the soil.

If hosts are lost or removed, studies suggest that ECM 

viability in the soil declines rapidly after two to three years 

(Haggerman and others 1999). Recovery of ECM communities from cutting, thinning, and burning may take decades 

(Visser 1995). It is not known how long whitebark pine ghost 

forests maintain viable ECM propagules (spores). Adverse 

management activities should be particularly minimized 

around “plus” trees and in relatively intact mature forests 

with healthy seedling regeneration. The impact on soil microbes under the canopy from Carbaryl and other chemicals 

used to prevent host attack by mountain pine beetles needs 

investigation.

Fire can affect ECM communities in soil with varying 

results, depending on the severity of the fire, forest type, 

and other factors (Cairney and Bastias 2007). High-intensity 

fires may eliminate ECM communities because of the deep 

depth of heating in the soil, the loss of original tree hosts, and 

changes in abiotic conditions, including an increase in soil 

surface temperature (Neary and others 1999). A comparison 

of the ECM fungi on whitebark pine seedlings in a severe 

burn and adjacent unburned forest revealed a shift in ECM 

fungal species, but the functional significance of this shift is 

unknown (Trusty and Cripps 2010). Five years after the fire, 

seedlings in the burn were partially colonized by suilloids,

likely due to the availability of a nearby inoculum source 

(adjacent unburned forest), the presence of vectors (deer and 

small mammals) that import inoculum, and a management 

plan that included planting one year after the burn (Trusty 

and Cripps 2010). The adverse effects of long delays before 

planting should be considered for severe burns (Wiensczyk 

and others 2002). In contrast, there is no evidence that light 

burns affect ECM fungi in whitebark pine forests, but a loss 

of seedlings could reduce ECM diversity due to the successional nature of these fungi. While some fungal species 

survive and rapidly re-colonize after fire, others do not, and 

removal of the duff layer can be problematic for some ECM 

fungi (Smith and others 2005).

Strategies for Maintaining ECM Fungi

Whitebark pine management strategies should consider 

factors known to help maintain diversity of ECM fungi in 

the soil. These include maintaining an intact forest floor, 

promoting the continuous presence of living host trees, 

and maintaining multiple age forests (Wiensczk and others 2002). In particular, maintenance of soil organic matter, 

nurse trees, logs (not stumps), and other microsite components may enhance fungal diversity (Tedersoo and others 

2008). For whitebark pine, we know that ectomycorrhizae 

occur in soil as well as in nurse logs (Cripps and others 

2008). Microsite plays a significant role in whitebark pine 

seedling establishment in general (McCaughey and others 2009). Management strategies that promote continuous 

host presence also function to preserve spore banks in soil 

(Kjöller and Bruns 2003). Since ECM fungi are successional, a mixed host age structure helps maintain fungal diversity 

for the next generation of trees. When continuity of the host 

is lost and plantings do not occur before spore banks become 

non-viable, it is possible that host-specific fungi will be lost.

Special consideration should be given to identification 

and preservation of ECM diversity “hot spots” and reservoirs 

of five-needle pine ECM fungi (the suilloids) in whitebark 

pine forests. Whitebark pine may derive some competitive 

advantage from these specialist fungi that do not form mycorrhizae with lodgepole pine, spruce, or fir. Suillus spp. 

associated with whitebark pine are restricted to five-needle 

or stone pines (Cripps and Antibus 2010). Host restriction is 

less clear for the Rhizopogon spp., which are also found with 

whitebark pine. Suilloids are important as ECM fungi that 

occur on all tree age classes from young seedlings to mature 

trees (Visser 1995) and because they have been used successfully for restoration purposes with other pines (Steinfield 

and others 2003). They are also important in the food chain 

(Izzo and others 2005; Johnson 1996). Rhizopogon produces 

reproductive structures underground and is dependent on 

mammals (for example, squirrels, deer, and bears) for spore 

dispersal, while Suillus spores are dispersed primarily by 

wind but also by animals (Ashkannejhad and Horton 2005). 

Practices that help maintain mammal vectors also promote 

these plant-fungal associations.

A few studies have examined planting whitebark pine 

seedlings with understory plants as a revegetation strategy (Mellman-Brown 2002; Perkins 2004). Some, such 

as Arctostaphylos spp., are potential reservoir plants 

that could share certain ECM fungi with pine seedlings. 

Arctostaphylos spp. are known to host five-needle pine ECM 

fungi for European stone pine (Krpata and others 2007) 

and limber pine (Cripps, personal observation). However, 

Arctostaphylos spp. are uncommon beneath whitebark pine 

in many areas. In one study, plant competition reduced survival of Pinus cembra seedlings planted in Arctostaphylos

spp. (Haselwandter 1997); however, Arctostaphylos spp. as 

an understory benefited Douglas-fir seedling regeneration 

(Horton and others 1999). A Vaccinium spp. understory may 
USDA Forest Service RMRS-GTR-279. 2012. 17

enhance seedling survival (Perkins 2004), but there is no 

definitive evidence to date that Vaccinium spp. share ECM 

fungi with whitebark pine seedlings; Vaccinum spp. typically host ericoid fungi.

The following is a list of management actions that can 

improve ECM diversity and accessibility:

• Minimize practices detrimental to soil microbes, as 

previously mentioned.

• Enhance practices that preserve the diversity of native 

ectomycorrhizal (ECM) fungi in soil.

• Plant seedlings near inoculum sources (living whitebark 

pines).

• Plant seedlings within a year after disturbances before 

ECM viability declines.

• Assess soils to determine if native ECM fungi are 

present.

• Inoculate nursery seedlings with native five-needle pine 

ECM fungi when lacking.

• Use native ECM fungal inoculum from the same or 

adjacent seed transfer regions.

• Monitor ECM colonization of planted seedlings.

• Minimize importation of alien ECM fungi (commercial 

inoculum or nursery fungi).

• Conserve and preserve suilloid fungi specific to fiveneedle pines.

Inoculation of Nursery-Grown Seedlings

Inoculation of nursery seedlings with native fungi should 

be considered when soils lack appropriate ECM fungi and 

when it is unlikely that soils will be imported in a timely 

manner (Brundrett and others 1996; Khasa and others 2009). 

Areas at high risk for lack of ECM fungi for whitebark pine 

are ghost forests, severe burns, and planting areas not previously inhabited by whitebark pine. This is particularly true 

for areas a distance from an inoculum source with few/no 

animal vectors present. Soils can be assessed for the presence of appropriate native ECM fungi through observation 

or with bioassay techniques (planting seedlings in native 

soils under greenhouse conditions). The use of site-adapted, 

host-specific native fungi that occur with whitebark pine is 

highly recommended as inoculum. This excludes the use of 

generally available commercial inoculum containing generalist fungi or those that promote lodgepole pine, spruce, fir, 

and other conifers.

Suillus spp. have been used successfully to regenerate 

stone pines in Europe for 50 years (Weisleitner, personal 

communication). Inoculation and colonization of whitebark 

pine seedlings with native fungi has been successful under 

greenhouse conditions, and Suillus spp. were the most vigorous colonizers for whitebark pine in greenhouse studies 

(Cripps and Grimme 2010). Fungal strains used in inoculation should be restricted to the appropriate seed transfer 

region or larger adjacent region (Sierra Nevada and northern 

Rocky Mountains). The transfer of exotic and alien ECM 

fungal species (including those in commercial inoculum) to 

whitebark pine areas should be minimized. The goal of inoculation is not to enhance growth of the pine, but to increase 

its survival and overall health. If possible, inoculated seedlings should be monitored to gain information. Some fungi 

specific for whitebark pine can be preserved in culture for at 

least several years by various methods (Cripps and Grimme 

2009).

There is no evidence that ECM fungi can directly mitigate the impacts of whitebark pine blister rust or mountain 

pine beetles. These detrimental organisms primarily affect 

the above-ground portion of trees, whereas ECM fungi occur on roots. However, appropriate ECM fungi are known to 

improve the general health of plants, enhance drought tolerance (a factor in beetle kill), and promote resistance to other 

pathogens. ECM fungi are critical to sustaining whitebark 

pine forests, and strategies that promote their continued existence should be considered.

Fire Regimes

Whitebark pine fire regimes are quite complex and variable in space and time, but in general, all three types of fire 

severities describe whitebark pine fire dynamics: non-lethal, 

stand-replacing, and mixed-severity (Arno and Hoff 1990; 

Barrett 2008; Campbell and others 2011; Larson and others 

2010; Morgan and others 1994b; Murray 2008; Siderius and 

Murray 2005). Some whitebark pine stands may experience 

low-intensity, non-lethal surface fires (sometimes called 

underburns or low-severity fires) because of sparse surface 

and canopy fuel loadings and unique topographical settings 

(Figure 1.14). These sites are mostly found in the southern 

parts of the species range in the Rocky Mountains or on 

high, dry ridges and may represent only a small portion of 

existing whitebark pine forests (less than 10 percent) (Keane 

and others 1994; Morgan and others 1994b). Whitebark pine 

can survive low-intensity surface fires better than most of its 

competitors, especially subalpine fir, because it has somewhat thicker bark, higher and thinner crowns, and deeper 

roots (Arno and Hoff 1990; Morgan and Bunting 1990; Ryan 

and Reinhardt 1988). As a result, non-lethal surface fires 

have historically maintained whitebark pine dominance in 

the overstory and prolonged whitebark pine cone production 

by stalling succession (Keane 2001b).

The more common, mixed-severity fire regime is characterized by severities that are highly variable in space and 

time, creating complex patterns of tree survival and mortality on the landscape (Murray and others 1998; Romme 

and Knight 1981; Siderius and Murray 2005) (Figure 1.15). 

Mixed-severity fires can occur at 60- to more than 300-

year intervals and sometimes over 500 years, depending 

on drought cycles, fuel conditions, landscape burn history, and high wind events (Arno and Hoff 1990; Morgan 

and others 1994b; Walsh 2005). Individual mixed-severity fires can be non-lethal surface fires with differential 
18 USDA Forest Service RMRS-GTR-279. 2012.

Figure 1.14. A low-intensity, non-lethal surface fire burning in a whitebark pine forest. The species is able to survive some of 

these fires because of high crowns and deep roots. However, the thin bark makes it susceptible to mortality when intensities 

are higher.

Figure 1.15. A common 

pattern created by mixedseverity fire in Yellowstone 

National Park.
USDA Forest Service RMRS-GTR-279. 2012. 19

mortality, variable mortality stand-replacement fires, and, 

most often, fires that contain elements of both (Morgan 

and others 1994b). Sometimes fires burn in sparse ground 

fuels at low-severities, killing the smallest trees and the 

most fire-susceptible overstory species, often subalpine fir 

(Walsh 2005). Severities increase if the fire enters areas 

with high fuel loads or if there are high winds or drought 

conditions because these situations facilitate fire’s entrance 

into tree crowns, thereby creating patches of fire-killed 

mortality (Lasko 1990). Burned patches are often 1 to 30 

ha in size, depending on topography and fuels, and these 

openings provide important caching habitat for the Clark’s 

nutcracker (Norment 1991; Tomback and others 1990) 

(Figure 1.15).

Many whitebark pine forests in the northern Rocky 

Mountains, Cascades, and Greater Yellowstone Area experience periodic large, stand-replacement fires that occur at 

long time intervals (greater than 250 years) (Figure 1.16). 

Stand-replacement fires also occurred within mixed-severity fire regimes but as infrequent events (Morgan and Bunting 

1989; Romme 1980). These fires are usually wind-driven; 

often originate in lower, forested stands (Murray and others 

1998); and create large burned patches on the landscape that 

may be distant from tree seed sources (Beighley and Bishop 

1990) (Figure 1.16). Whitebark pine has an advantage over 

its competitors in that it readily colonizes large, standreplacement burns because its seeds are transported great 

distances by Clark’s nutcracker (Lorenz and others 2008; 

Tomback 1982, 2005). Nutcrackers can disperse whitebark 

pine seeds up to 100 times farther (over 10 km) than wind 

can disperse seeds of subalpine fir and spruce (McCaughey 

and others 1985; Tomback and others 1990, 1993). Since 

nutcrackers often prefer open sites with many visual cues 

for seed caching, stands burned by mixed-severity or standreplacement fire provide favorable sites for nutcracker 

caching and competition free seedling growth (McCaughey 

and Weaver 1990; Sund and others 1991; Tomback 1998). 

Murray and others (1995) found that larger burns were associated with greater volume per hectare of whitebark pine 

as compared to smaller burns in the Bitterroot Mountains.

Whitebark pine benefits from wildland fire because it 

is better adapted to surviving fire and also to regenerate in 

burned areas than associated shade-tolerant trees (Arno and 

Hoff 1990). Without fire, most seral whitebark pine forests 

would be successionally replaced by subalpine fir or some 

other shade-tolerant high-elevation species. Fire, whitebark pine, and the Clark’s nutcracker form an important 

high-mountain ecological triangle. Virtually all whitebark 

pine regeneration comes from nutcracker caches, where 

unclaimed seeds eventually germinate and grow into seedlings. These seeds are often cached in open, pattern-rich 

landscapes that facilitate efficient retrieval of seeds, and 

these landscapes are commonly created by wildland fire. 

Once whitebark pine seeds cached in burned areas have 

germinated, those seedlings have a good chance to grow 

into mature trees because they can grow free from competition for a long time. Remove any one of the sides of the 

triangle and this keystone ecosystem is lost.

Figure 1.16. Large burned areas created by stand-replacement fires in whitebark pine.
20 USDA Forest Service RMRS-GTR-279. 2012.

Importance of Whitebark Pine

Whitebark pine occurs in seven western states and two 

Canadian provinces; it has the broadest latitudinal distribution of any five-needle white pine in the United States 

and Canada (Tomback and Achuff 2010). In the northern 

Rocky Mountains alone, whitebark pine communities represent about 10 to 15 percent of the forested landscape 

(Arno 1986). More than 95 percent of whitebark pine in the 

United States occurs on public lands, including National 

Forests, Wilderness Areas, and National Parks. The three 

largest Wilderness Areas in the western United States each 

comprise about 25 to 50 percent potential whitebark pine 

forest habitat (Keane 2000).

The importance of whitebark pine, however, transcends 

its widespread occurrence in that, throughout its distribution, whitebark functions as both a keystone and foundation 

species (Tomback and Achuff 2010; Tomback and others 

2001a). Keystone species promote community diversity 

disproportionately in relation to their abundance through 

interactions with other species (Mills and others 1993; 

Soulé and others 2003). Foundation species are regarded 

as a single species that influences community structure by 

“...creating locally stable conditions for other species, and 

by modulating and stabilizing fundamental ecosystem processes” (Dayton 1972; Ellison and others 2005). Whitebark 

pine assumes these ecological roles as a result of the following traits: large, nutritious seeds; seed dispersal by 

Clark’s nutcrackers; hardy, robust seedlings; and tolerance 

for cold, windy sites (McKinney and Tomback 2011). This 

section details the value of whitebark pine to society.

Ecological Processes and Ecosystem Services

Whitebark pine promotes regional biodiversity as a keystone species in several ways (for reviews, see Tomback 

and Achuff 2010; Tomback and others 2011). Its large seeds 

are an important wildlife food, supporting a community of 

granivorous mice, squirrels, and birds, as well as grizzly 

and black bears (Ferner 1974; Hutchins 1994; Hutchins 

and Lanner 1982; Mattson and others 1991; Tomback 

1978, 1982; Tomback and Kendall 2001). Whitebark pine 

grows at the highest forest elevations, providing habitat and nesting sites for many diverse species including 

grouse, deer, elk, birds of prey, foxes, coyotes, and other 

predators (Tomback and Kendall 2001; Tomback and others 2001a). Across its broad latitudinal distribution and 

eastern and western ranges, whitebark pine encompasses 

a variety of forest communities with different associates, 

successional stages, and understory diversity (Arno 2001; 

Arno and Hoff 1990; Tomback and Kendall 2001).

Whitebark pine promotes biological community development and stability after disturbance and within climax 

and treeline communities. Because nutcrackers readily 

cache seeds in burned or otherwise disturbed terrain and in 

large forest openings, whitebark pine regeneration occurs 

rapidly. The seedlings tolerate harsh conditions and poor 

soils, although regeneration may be delayed by droughty 

conditions (Tomback 1986; Tomback and others 1990, 

1993). As whitebark pine seedlings grow, they provide 

shade and favorable micro-environments for the establishment of other conifers and understory vegetation (Callaway 

1998). Furthermore, whitebark may act as a “nurse” tree on 

harsh sites in the subalpine zone, protecting smaller spruce 

and fir from strong winds and ice abrasion (Callaway 

1998). In the Rocky Mountain Front of Montana, east of 

the Continental Divide, treeline conditions are particularly 

extreme. There, the microsites selected by nutcrackers for 

caching seeds combined with the hardiness of whitebark 

pine seedlings result in the establishment of solitary whitebark pine trees that moderate wind effects on their leeward 

side and enable the establishment of other conifers, resulting in the development of tree islands. Consequently, 

whitebark pine is the most common species to initiate tree 

islands in these harsh environments (Resler and Tomback 

2008).

The higher mountains of the world are increasingly recognized as important “water towers” that play crucial roles 

in supplying water for downstream agriculture and human 

consumption (Messerli and others 2004). Throughout much 

of its broad range, whitebark pine inhabits the highest elevations where other conifers are often sparse. Whitebark 

pine forests and treeline communities stabilize and shade 

snowpack, thus regulating melt-off and downstream flow; 

stabilizing loose, rocky soils; and reducing erosion (Arno 

and Hammerly 1984; Arno and Hoff 1990; Farnes 1990; 

Hann 1990).

Recreation

Each year, tens of millions of people visit whitebark pine forests in National Parks, National Forests, 

Wilderness Areas, and ski areas (Cole 1990). Murray 

(2005) estimated that nearly 2.5 million mountain tourists encounter whitebark pine stands every year in Oregon 

alone. These picturesque forests often surround high-elevation lakes or viewpoints, where most day-hikes end, 

and treeline whitebark pine communities accompany trails 

leading up to and down from mountain passes. The most 

common recreational activities in and around whitebark 

pine forests are horsepacking, skiing, hiking, camping, and 

fishing (Figure 1.17). Snowmobiling, four-wheel driving, 

and mountain biking are additional forms of recreation providing access to these scenic, high-elevation communities. 

Whatever the activity, visitors to whitebark pine generally 

(1) enjoy and appreciate the high-mountain scenery, (2) assume the forests have not been altered by humans, and 

(3) have sought out these forests for their remoteness and 

isolation. Studies have shown that intensive recreational 

use of high-elevation areas, particularly through hiking, 

use of pack stock, and creation of campsites, has resulted in 

forest degradation (Cole 1990). Guidelines for responsible 

recreation in these areas and enforcement of these guidelines would reduce further impacts.
USDA Forest Service RMRS-GTR-279. 2012. 21

Cultural Heritage

In years of good cone production, whitebark pine seeds 

were harvested by many Native Americans (First Peoples) of 

the United States and Canada. The seeds were traditionally 

served as an important winter food source, eaten raw or roasted. Seeds were also cooked, mashed, and mixed with service 

berries (Moermond 1998). For example, the interior Salish 

from British Columbia to Montana extensively harvested 

whitebark pine seeds, which were apparently more popular 

than seeds from the lower-elevation ponderosa pine (Pinus 

ponderosa) (Lee 2003). Archeological sites, such as the highelevation campsites found along the Bitterroot Divide near 

Lolo Pass in Montana indicate that Native Americans used 

whitebark pine seeds for both short- and long-term food supplies (Losensky 1990). Cheff (1993) described his trips with 

the Flathead tribe into the Mission Mountains of Montana to 

harvest whitebark pine seeds. There, the trees would be literally bent over with the weight of whitebark pine cones, and 

it took only a short time to harvest a packhorse load. Women 

of the southern Okanagan and Thompson tribes in British 

Columbia often gathered cones in late summer while the men 

were hunting. The cones were dry-baked in an earthen oven 

for a day, and the seeds were extracted and stored for winter 

cooking or for trading for other goods (Turner and others 1980, 

1991). Native Americans still value whitebark pine seeds, and 

are maintaining traditional seed collecting activities.

The Secwepemc and Flathead Salish also harvested the 

inner bark (cambium and secondary phloem tissues) of 

a variety of pines, including whitebark pine, for food and 

medicine (Kuhmlein and Turner 1991; Turner and others 

1980). In the spring, pine bark was generally stripped from 

the north side of trees, with harvesters being careful not to 

over strip or girdle trees, and the sweet and juicy cambium 

was eaten or used as a medicine for stomach problems like 

ulcers (Kuhmlein and Turner 1991; Turner and others 1980). 

The “catface” scars indicative of bark stripping have recently been found on whitebark pine in northwestern Montana, 

providing evidence that the inner bark of this species might 

have been used as a food source in this region (Arno and 

others 2008). The fibrous roots of whitebark pine were used 

to sew bark together and to weave water tight containers 

(Antos and others 1996), and the wood was used for firewood (Losensky 1990).

Timber

The scale of commercial logging of whitebark pine has 

been limited by the remote high elevations settings and the 

relatively poor quality of its timber—notably its twisted 

grain, brittleness, and growth form (Rockwell 1911). In fact, 

John Muir (1894) referred to whitebark pine as the “dwarf 

pine,” noting its growth habit as a small tree or prostrate 

form and occurrence at the highest elevations in the Sierra 

Nevada. However, beginning in the mid-1800s, whitebark 

pine was harvested in association with the growing mining industry throughout the American West. From 1860 

to 1940, for example, billions of board feet of whitebark 

pine were cut to support the Montana mining industry; the 

wood was used for fuelwood in smelters and to heat miners’ 

homes (Losensky 1990). In Montana and Idaho, whitebark 

pine saplings were widely used by ranchers as fence posts 

(Rockwell 1911). In the northern Rocky Mountains of the 

United States and Canada, whitebark pine attains a growth 

form similar to lodgepole pine (Pinus contorta) on welldeveloped soils and protected sites; it has been commercially harvested along with lodgepole pine (Day 1967; Rockwell 

1911). Commercially usable stem lengths exceeding 18 m 

(60 ft) have been recorded for whitebark pine, with records 

from southern British Columbia and Alberta (Day 1967).

Figure 1.17. Park-like stand of 

whitebark pine trees on a 

climax site that is a popular 

hiking destination. (Photo 

courtesy of Steve Arno.)
22 USDA Forest Service RMRS-GTR-279. 2012.

Presently, however, whitebark pine is not a commercially 

important timber species and harvest throughout its range 

is negligible for two reasons. First, its remote locations 

preclude accessibility for the extensive timber harvesting 

equipment and road building. Second, the trees are short, 

gnarled, and have extensive taper, thereby decreasing their 

timber desirability; whitebark pine trees rarely grow to a size 

and structure that would be considered high-quality for lumber or other wood products. While the wood is generally as 

strong as other soft pines, it is considerably weaker than the 

hard pines and its wood grain is often spiraled (Kasper and 

Szabo 1970; Keenan and others 1970). Whitebark pine trees 

cut for timber in the lower reaches of its elevational limit 

are often within a timber sale for lodgepole pine. Less than 

1000 ha of the whitebark pine forests in the United States 

are harvested during any given year (Losensky 1990). Chew 

(1990) presented some possible target stand conditions for 

whitebark pine forests in the northern Rockies, while Eggers 

(1990) presented alternative silvicultural recommendations 

for managing whitebark pine for grizzly bear and wildlife. 

The British Columbia Ministry of Forests encourages forest professionals to make minor amendments to harvest 

and planting planning to help conserve the species (B.C. 

Ministry of Forests 2008).

Grizzly and Black Bears

Grizzly and black bears consume substantial amounts 

of pine seeds in only small parts of their historical North 

American range (Figure 1.18). Heaviest bear use of seeds 

occurs in the GYA and the eastern front of the Montana 

Rocky Mountains, which are regions that experience a 

continental climate (Mattson and others 2001). Many researchers have found that pine seeds are an important 

food source for grizzly bears in these regions (Craighead 

and others 1982; Felicetti and others 2003; Kendall 1983; 

Kendall and Keane 2001; Mattson 1997; Mattson and 

Reinhart 1994). Year-to-year variation in whitebark pine 

cone production impacts grizzly bear ecology and demographics in the GYA (Interagency Grizzly Bear Study 

Team 2009), particularly influencing rates of movement 

(Blanchard and Knight 1991), diet (Felicetti and others 

2003; Mattson 1997; Mattson and others 1991), mortality 

rate (Blanchard 1990, Mattson and others 1992), distribution of bears (Haroldson and others 2004), probability of 

survival (Haroldson and others 2006), and reproductive 

rates (Schwartz and others 2006).

Whitebark pine seeds have several features that make 

them a valuable food source for bears. They are large, 

which makes the seed easier to eat and more energetically 

rewarding for grizzly bears to consume. They are highly 

nutritional—whitebark pine seeds are characterized by 21 

percent protein (Lanner and Gilbert 1994) and lipid contents ranging from 28 percent (Robbins and others 2006) 

to 52 percent (Lanner and Gilbert 1994). And they are easy 

to obtain from squirrel middens. The seeds are especially 

important for female grizzly bears; reproductive success 

of females is contingent on the accumulation of body fat. 

Female grizzly bears in the GYA derive 40 to 50 percent 

of their fall nutrition from whitebark pine nuts (Felicetti 

and others 2003). Female grizzly bears that frequently 

use whitebark pine seeds exhibit substantially higher reproductive rates (larger litters, more likely to reproduce, 

and reproduce at a significantly earlier age) than females 

who consumed few pine seeds (Mattson and others 2001; 

Robbins and others 2006). Feeding on whitebark pine 

seeds also promotes high survivorship of sub-adult males 

and adult females.

The abundance of red squirrels and their middens of 

stored whitebark cones are important influences on the 

extent and character of black and grizzly bear use of whitebark pine seeds in any region. In the GYA, bears acquire 

almost all (greater than 90 percent) whitebark pine seeds 

by excavating red squirrel middens (Mattson and Reinhart 

1994). Red squirrels typically harvest whitebark pine and 

other conifer cones in August and September to cache in 

territorial middens (Hutchins 1994; Kendall 1983). Bears 

seek out these hoards to excavate and consume whitebark 

pine seeds in their attempt to accumulate body fat prior 

to hibernation (Mattson and others 1994). Whitebark pine 

cone crops vary in size annually, and, when whitebark pine 

seeds are abundant and available, bears almost exclusively 

consume pine seeds (Mattson and others 2001).

Most middens excavated by bears coincide with years 

of large cone crops (Mattson and others 2001; Podruzny 

and others 1999). Grizzly bear use of squirrel middens 

can start as early as late July; heavy use typically does 

not occur until the last week of August or the first week of 

September and persists until bears den in late October and 

early November. If a substantial number of cones remain in 

squirrel middens, bear use resumes typically by early June 

of the following year and lasts until cones are depleted. 

When bears feed on pine seeds, they feed on virtually nothing else (Mattson and others 2001).

Because of the relationships among whitebark pine 

seeds, red squirrels, and bears, management of whitebark 

pine and grizzly bear habitats should take into account 

red squirrel densities and cone harvesting opportunities 

(Mattson and others 2001; Reinhart and Mattson 1990). 

Red squirrels require a diverse conifer species overstory 

in order to maximize foraging during variable pine cone 

crop years (Smith 1968). Density of red squirrel middens excavated by Yellowstone grizzly bears was highest 

in forest types dominated by a mix of whitebark pine and 

lodgepole pine (Mattson and Reinhart 1997). The best red 

squirrel habitat within the whitebark pine zone consists of 

forest habitats with high overstory basal area and high conifer species diversity on moderate slopes (Reinhart and 

Mattson 1990; Podruzny and others 1999). Optimum stand 

characteristics that favor red squirrels and grizzly bear use 

of whitebark pine seeds occur when conifer basal area is 

greater than 40m2 ha-1 and whitebark pine basal area represents 15 to 50 percent of the total basal area (Mattson 

2000). Management practices for whitebark pine forests 
USDA Forest Service RMRS-GTR-279. 2012. 23

where bears frequently consume pine seeds should strive 

to optimize red squirrel habitat. Restoration efforts should 

also strive to maintain wildlife relationships by maximizing 

conifer species overstory diversity and preserving mature, 

seed-producing whitebark pine trees. In grizzly bear habitat, permanent access must be limited (Mattson and others 

2001). Restoration efforts throughout whitebark pine range 

would benefit all wildlife species that take advantage of 

the foraging value of whitebark pine seeds. Grizzly bears 

may suffer from the short-term effects of large-scale disturbances, such as fire, mountain pine beetle outbreaks, and 

timber harvest, which remove cone-producing whitebark 

pine and reduce squirrel densities and midden sizes. The 

1988 fires in Yellowstone burned 30 percent of cone-producing whitebark pine stands in the north and 12 percent in 

the east portion of the Park, potentially affecting the availability, amount, and distribution of food sources for bears 

in the Park (Renkin and Despain 1992).

Annual variation in whitebark pine cone production indirectly relates to human-caused bear mortality and adverse 

encounters. During years of abundant whitebark pine cone 

crops in the Greater Yellowstone Area, bears forage almost 

exclusively on pine seeds in the high-elevation whitebark 

pine zone (Mattson and others 2001; Podruzny and others 1999). When bears stay in the more remote whitebark 

pine zone, they are farther away from human facilities, 

campgrounds, big game hunting areas, and potential human-bear conflicts. Human-bear conflicts are the leading 

cause of bear mortality. During years when bears eat few 

pine seeds, conflicts with humans and associated bear mortality increase dramatically (Mattson and others 1992). 

National Forest System, Bureau of Land Management, 

and National Park System in Idaho, Montana, Washington, 

and Wyoming have adopted Interagency Grizzly Bear 

Guidelines for managing lands to favor grizzly bear use 

over human use while emphasizing actions that contribute 

to grizzly bear recovery and conservation (IGBC 1986).

Current Status

The rapid decline of whitebark pine across most of its 

range in North America is mostly a result of multiple recent 

human-caused and natural events (Arno 1986; Kendall 1995; 

Kendall and Keane 2001; Tomback and others 2001a; for recent reviews, see Tomback and Achuff 2010 and Tomback 

and others 2011). First, several major natural mountain pine 

beetle outbreaks over the last 70 years have killed many 

cone-bearing whitebark pine trees across the species’ range 

(Arno 1986; Baker and others 1971; Waring and Six 2005). 

The most recent mountain pine beetle outbreak, which began in the late 1990s, has achieved unprecedented intensity 

and geographic extent, driven by rising temperatures that 

many associate with anthropogenic climate warming (Logan 

and Powell 2001). Next, an extensive and successful fire 

exclusion management program in western North America 

has reduced the area that can be potentially inhabited by 

the shade-intolerant whitebark pine. Because of fewer fires 

now, late successional whitebark pine communities are increasingly common and early successional communities 

are increasingly rare, resulting in a cumulative decline of 

whitebark pine at a landscape scale over time (Keane and 

Arno 1993; Morgan and Bunting 1990; Murray and others 

2000). And finally, potentially the most threatening events 

were multiple introductions of the exotic fungal pathogen Cronartium ribicola to the western United States and 

Canada in the early 1900s, which causes the disease white 

pine blister rust (Geils and others 2010; McDonald and Hoff 

2001). Whitebark pine is among the most susceptible to blister rust of the five-needle white pines (Hoff and others 1980; 

Kendall and Keane 2001; Schwandt 2006).

Figure 1.18. Grizzly bears eating whitebark pine seeds. (Photo courtesy of Kate Kendall.)
24 USDA Forest Service RMRS-GTR-279. 2012.

The cumulative effects and interactions of these three 

agents have resulted in a rapid decrease in mature whitebark pine, particularly in the more mesic parts of its range 

(Campbell and Antos 2000; Elderd and others 2008; Keane 

and Arno 1993; Six and Adams 2007). Moreover, predicted changes in northern Rocky Mountain climate brought 

about by global climate change could further accelerate the 

decline of this important tree species by increasing the frequency, intensity, and duration of beetles and fire (Logan 

and Powell 2001; Romme and Turner 1991; Running 

2006). In the following sections, we detail the current 

threats to whitebark pine and the extent of decline across 

the species’ range.

Blister Rust

White pine blister rust is an exotic fungal disease of 

five-needle pines, including white, stone, and foxtail pines 

(Burns and others 2007). It was introduced to western 

North America around 1910 on infected eastern white pine 

nursery stock grown in France and shipped to Vancouver 

British Columbia. Since then, it has spread throughout 

the range of most five-needle pines in the United States 

and Canada. It was once thought that cold, dry, and hot 

environments of western North America were inhospitable to the rust, but the rust now infects pines in even the 

most severe climates (Burns and others 2008; Resler and 

Tomback 2008).

Cronartium ribicola has a complex life cycle involving five different spore types on two groups of alternate 

hosts (Figure 1.19). Blister rust cankers on the white pine 

hosts produce aeciospores, which transmit the disease to 

the alternate hosts, which most commonly comprise shrubs 

of genus Ribes, but also may include plants of the genera Pedicularis and Castilleja (Geils and others 2010). 

Basidiospores produced by the alternate hosts are fragile, short-lived spores that infect pines by entering needle 

stomata. This stage of the life cycle is most climatically 

limited, requiring moderate temperatures and high humidity for spore production and transmission to pines. 

Basidiospores typically may travel only a short distance by 

wind—most often a few hundred meters but up to about 8 

km. Spores that germinate within the needle tissue produce 

hyphae, which then grow into the vascular system and the 

needle stem (see McDonald and Hoff 2001; Geils and others 2010 and references therein). The hyphae grow down 

the branch and eventually into the tree bole. There, they 

eventually form a canker in which spore structures called 

Figure 1.19. Life cycle of 

the blister rust (from 

McDonald and Hoff 

2001).
USDA Forest Service RMRS-GTR-279. 2012. 25

pycnia produce pycniaspores, which are not infectious but 

are needed for fertilization by insects. Aeciospores are produced from fertilized pycnia the following year in the early 

summer within bright orange blisters or aecia. These aeciospores are hardy with thick walls and can travel great 

distances (more than 100 miles) to infect Ribes spp. Fragile 

orange urediniospores are produced in uredinia pustules on 

the underside of Ribes spp. leaves to infect other Ribes spp. 

shrubs throughout the summer. In the fall, teliospores form 

on infected Ribes spp. leaves and these germinate to form 

the basidiospores that infect the pine.

White pine blister rust damages and kills whitebark 

pine trees by girdling branches and stems (Hoff 1992) 

(Figure 1.20), thereby reducing seed cone production 

within trees and across forest stands. In the Bitterroot 

Mountains of western Montana and eastern Idaho for example, whitebark pine cone production was significantly 

lower in stands with higher rust damage (canopy kill and 

tree mortality) compared to stands with lower rust damage 

that were otherwise not different in forest structure, composition, slope, and elevation (McKinney and Tomback 

2007). Across a broader geographic area—from northwest 

Wyoming to northwest Montana—whitebark pine cone 

production was positively correlated with live whitebark 

pine basal area and negatively correlated with whitebark 

pine tree mortality at the site level (McKinney and others 

2009). Thus, blister rust directly constrains the ability of 

individual trees and forest stands to contribute propagules, 

and hence genetic material, to subsequent generations. This 

reduction in regeneration potential is further exacerbated 

by a suite of vertebrate species interactions that are altered 

both directly and diffusely by disproportionate whitebark 

pine mortality and reduced seed cone availability.

Resistance of whitebark pine to white pine blister rust 

ranges from 33 percent in a small sample (n = 3) (Hoff and 

others 1980) to 47.4 percent (n = 108) (Mahalovich and 

others 2006; Mahalovich 2012) in the Inland Northwest 

and 26.3 percent (n = 43) on the Pacific Coast (Sniezko 

and others 2007). Seeds from the healthy trees in stands 

heavily infected and damaged by blister rust would have 

the highest probability of being somewhat resistant to blister rust. If opportunities for regeneration are not provided 

until most of the whitebark is dead or no longer producing 

cones, the surviving (rust-resistant) trees will be at such 

low numbers that virtually all of their seeds will be eaten 

(McKinney and Tomback 2007). Some landscapes contain 

so few apparent rust-resistant whitebark pine seed sources 

that there is major concern that nutcrackers will consume 

a majority of the seed collected and their cached seed will 

be mostly reclaimed.

There have been many failed attempts at the control of 

white pine blister rust in the past. Attempts at eradicating 

Ribes spp. during 1940 to 1960 were largely unsuccessful because the shrubs can vegetatively regenerate from 

rhizomes and their seeds are stored in the soil where they 

can be activated for germination by future fires. Aerial 

applications of antibiotic solutions in diesel oil sprayed 

on whitebark pine to combat blister rust were mostly ineffective and costly (Brown 1969; Maloy 1997). Several 

management actions, such as pruning infected branches 

and thinning infected trees, may forestall rust mortality 

(Fins and others 2001).

Mountain Pine Beetle

The principal agent of insect-caused mortality of whitebark 

pine is the mountain pine beetle (Figure 1.21). It is a native, 

cambial-feeding bark beetle of all the western pines, including western white, whitebark, limber, and lodgepole pines. Its 

entire life cycle is spent beneath the bark of host trees, except 

when adults emerge from brood trees and fly in search of 

new host trees. Trees defend themselves with various chemicals, but these matchhead-size beetles can overwhelm these 

defenses with a mass attack strategy through sheer numbers 

of beetles (Logan and Powell 2001). Mountain pine beetles 

range from the Pacific Coast east to the Black Hills of South 

Dakota and from northern British Columbia and western 

Alberta south into northwestern Mexico.

Figure 1.20. A whitebark pine stand killed by white pine 

blister rust.
26 USDA Forest Service RMRS-GTR-279. 2012.

Mountain pine beetle is recognized as an aggressive and 

economically important forest insect responsible for tree 

mortality across large areas, and as an integral component of 

forest ecosystem dynamics for its role in stand thinning and 

redistribution of resources and nutrients for tree regeneration 

(Raffa and others 2008). Beetle outbreaks can cause dramatic 

tree mortality over extensive areas in only a few years, often 

killing the largest host trees in high-density stands. Beetles 

are present at low and endemic levels when population dynamics are considered “stable” or self-regulating and tree 

losses are negligible (Berryman 1986). However, mountain 

pine beetles can reach epidemic levels, killing up to 80 to 

95 percent of suitable hosts when populations are unstable, 

environmental conditions are favorable, and host species 

plentiful (Berryman 1986). Forest managers should consider 

the 95 percent figure a realistic upper bound of overstory 

mortality in epidemic conditions, including the circa 2000 

(1998 to present) west-wide epidemic (Schwandt 2006). 

Gibson and others (2008) reported that of all the high-elevation five-needled pine species, whitebark pine has sustained 

the highest mortality in nine western states.

Mountain pine beetles are native to high-elevation pine 

forests. Periodic outbreaks have occurred since the evolution 

of bark beetles and gymnosperms millions of years ago. For 

the 100+ years for which we have records, mountain pine 

beetles have impacted host stands, including whitebark and 

limber pine in many parts of the United States and Canada 

(Figure 1.22). In the early Twentieth Century, Craighead 

(1925) and Bureau of Entomology mentions that Renner 

(1929) documented the start of the widespread mountain pine 

beetle epidemic that occurred during the historically warm 

and dry period of the 1930s (Arno and Hoff 1990; Ciesla and 

Furniss 1976; Perkins and Swetnam 1996). Pre-Twentieth 

Century mountain pine beetle-caused mortality dates, such 

as 1730, 1819, and 1887, have been inferred from whitebark 

pine tree-ring records (Perkins and Swetnam 1996) and lake 

core sediments with Dendroctonus spp. remains, and whitebark pine pollen has been found dating back to the Holocene 

approximately 8200 years before present (Brunelle and others 2008).

Most of the mountain pine beetle life cycle is completed 

under the bark where the insect disrupts the connectivity of 

the water transport system of the tree, damaging the tree by 

mechanically girdling the stem with adult and larvae galleries in the phloem, and introducing a blue stain fungus that 

inhibits water transport and may kill the tree (Gibson and 

others 2009). Signs of mountain pine beetle attack are pitch 

tubes and fine boring dust in bark crevices and around tree 

bases, which are made when beetles bore into the bole of the 

tree. On successfully attacked trees, pitch tubes are abundant 

on the surface of the bole and may extend more than 5 m up 

the stem. Pitch tubes are cream- to dark red-colored masses 

of resin mixed with boring dust and are approximately 1 cm 

in length. Unsuccessful attacks are called “pitch outs”; the 

tree’s resin response is to pitch out the beetles as they attempt 

to bore into the inner bark. These pitch tubes are generally 

larger in size, lighter in color, and widely scattered over the 

trunk. Whitebark pine, like other pines, may sustain “strip 

attacks” where a vertical portion of inner bark is killed while 

the rest of the stem is unaffected and continues to transport 

Figure 1.21. The mountain pine beetle.

Figure 1.22. Whitebark pine stand killed by mountain pine 

beetles.
USDA Forest Service RMRS-GTR-279. 2012. 27

water and nutrients. Foliage of successfully attacked trees 

generally fades uniformly through the crown from yellowish green to shades of orange, rust, and red. Whitebark pine 

crowns generally fade to a rust color the year after attack, 

but may take two to three years in some individuals. Size, 

stress, and health of the tree are factors that affect the foliage 

fade rate.

Adult mountain pine beetles begin attacking trees in the 

early summer in pheromone-mediated mass attacks that overcome most of a tree’s chemical defenses. Beetles develop 

through four stages: egg, larva, pupa, and adult (Gibson and 

others 2009). Adults mate and then lay eggs that hatch into 

larvae that develop in the phloem of the tree completing the 

life cycle—a one year or univoltine life cycle. Larval growth 

is aided by a symbiotic fungi Grosmannia clavigera and 

Ophiostoma montium (Adams and Six 2007; Six 2003; Six 

and Paine 1998). Adult beetles deposit the fungi in the tree as 

they excavate galleries where the females lay eggs. The fungi 

colonize the phloem and sapwood of the infected tree, with 

the fungal hyphae providing nutrition to beetle larvae (Six 

2003). Adult beetles also feed on fungal spores in the pupal 

chambers before emergence and dispersal from the host tree. 

One to several months after the tree in infested, the sapwood 

discolors to a bluish tint caused by the fungi. Adult bark beetle galleries found under the bark are J-shaped and vertically 

aligned with the stem; larvae galleries are perpendicular to 

the adult galleries and terminate in pupae chambers. Adult 

galleries range in length from 5 to 7 cm to more than 60 cm 

and are diagnostic of mountain pine beetle attack.

Beetle life cycles take one to two years, and many empirical, laboratory, and modeling research studies have been 

undertaken to understand the causes of life cycle variability (Bentz and others 1991; Logan and Powell 2001; Powell 

and others 1996). Over most of its range, the beetle has 

one generation per year, but two generations have been observed in cooler, high-elevation areas, including whitebark 

forests. These forests have generally been associated with 

decreasing beetle-caused mortality levels because the cold 

environment creates unfavorable heat balance for beetle 

development (Amman 1973; Logan and Bentz 1999). Cool 

temperatures may retard development, resulting in longer 

life cycles and/or a disruption of critical timing of summer 

emergence necessary for a coordinated and successful mass 

attack. Mountain pine beetles have mechanisms to survive 

in sub-zero temperatures; however, sustained sub-freezing 

temperature may result in mortality in all life stages (Amman 

and Cole 1983; Regniere and Bentz 2007).

Beetle development is under direct temperature control 

(Logan and Bentz 1999), and warm temperatures favor 

successful brood development, beetle survivorship, and 

successful attacks (Amman 1972, 1973; Bentz and others 

1991; Logan and Bentz 1999; Reid and Gates 1970). The 

climate conditions during the early Twentieth Century epidemic and the current epidemic have been characterized 

by above average departures in summer temperatures. This 

has contributed to outbreak extent and magnitude by improving conditions for the mountain pine beetle’s adaptive 

seasonality and population build up (Logan and Bentz 1999; 

Logan and Powell 2001). Generally, epidemics collapse due 

to one of two factors: (1) an extreme cold snap (less than 

0 ̊ F) in early fall or late spring and winter temperatures below -34 ̊ F (Cole and others 1989); (2) a lack of susceptible 

host trees. Resource managers may be prudent to assume 

that the epidemic of the proportions that North America is 

currently experiencing will collapse when mountain pine 

beetle has run out of suitable hosts. The upper bound of 

95 percent mortality of the overstory, or the “worst case scenario” (Berryman 1986), provides a quantitative metric of 

stand structure that silviculturists can use for restoration actions. Forecasting a cold event is nearly impossible due the 

high temperature variability in time and space.

Mountain pine beetle mortality influences canopy condition, stand structure, species composition, forage production, 

wildlife habitat, fuel loading, water yields, and aesthetics. 

Following the death of the overstory, advanced regeneration 

from shade-tolerant tree species (subalpine fir, for example) 

is expected to release. Species composition plays a critical 

role at this time; if the stand has succeeded to shade-tolerant 

species, it would be expected that the stand composition 

would shift to that shade-tolerant species mixture. If the 

stand composition is homogenous or climax whitebark, 

whitebark would be expected to persist on the site. White 

pine blister rust-infected regeneration, suppressed seedlings, 

changing climates, and other disturbances confound the expected successional trajectory, and management intervention 

may be needed to maintain whitebark pine. A combination of 

silvicultural treatments, prescribed fire, fuel reduction, and 

planting of blister rust-resistant seedlings may be recommended. Resource managers should integrate actions that 

help whitebark pine ecosystems forestall beetle impacts and 

protect seed resources (Millar and others 2007).

It has been well established that tree size, age, and stand 

density are factors positively correlated with tree mortality 

(Hamilton 1986; Hamilton and Edwards 1976; Lee 1971; 

Yoda and others 1963). For the whitebark pine-mountain 

pine beetle system, diameter and basal area were significant 

predictors of beetle caused mortality in the reconstructed 

MPB outbreak of the 1930s (Perkins and Roberts 2003). 

This is consistent with MPB-host susceptibility characteristic of other pines (Amman and others 1977; Berryman 1982; 

Cole and Amman 1980; Olsen and others 1996; Stevens and 

others 1980; Schimd and Mata 1992; Shore and Safranyik 

1992). Mountain pine beetles prefer to attack large trees in 

dense stands. Whitebark pine stands with basal areas greater 

than 10 m2 ha-1 or with a stand density index (SDI) greater 

than 80 were attacked during the 1930s epidemic (Perkins 

and Roberts 2003). Other studies are being conducted to 

quantify vunerable stand structures.

Approaches to forestall or reduce mountain pine beetlecaused mortality have covered a broad spectrum. Efforts by 

the U.S. Forest Service in the early part of the Twentieth 

Century were aimed largely at killing beetles. The Forest 

Service, organized in 1905, was faced with its first beetle 

outbreak in the northern Rocky Mountains within a few 
28 USDA Forest Service RMRS-GTR-279. 2012.

years of its inception. Infested trees were peeled, piled and 

burned, and treated with toxic chemicals—or an array of 

those treatments in varying combinations—for more than 

50 years. Finally realizing the futility of trying to kill enough 

beetles to halt an outbreak, Forest Service entomologists and 

silviculturists began to recognize that stands of certain conditions experienced higher numbers of beetle-killed trees. 

By the 1970s, it was noted that lodgepole and ponderosa 

pine stands, especially susceptible to beetle outbreaks, 

shared similar characteristics—generally larger-diameter, 

older trees, in more densely stocked stands (Amman and 

others 1977). That recognition led to thinning studies and 

ultimately management recommendations directed at altering susceptible stand conditions to reduce beetle-caused 

mortality to acceptable levels (McGregor and others 1987). 

Current recommendations include reducing stand stocking 

to levels promoting vigorous tree growth and creating more 

open conditions that are less likely to attract and support 

beetle outbreaks (Safranyik and Wilson 2006).

Fire Exclusion

In general, the effects of fire exclusion in whitebark pine 

forests are not yet manifest because of the long fire return 

intervals associated with the ecosystem. Therefore, fire exclusion effects can only be evaluated at the landscape level by 

assessing the decrease in the extent of whitebark pine forests 

(early to mid-seral stands) and increase in subalpine fir (late 

seral) forests (Keane and others 1994). A major reduction in 

high-elevation fires since circa 1929 has led to the successional replacement of whitebark pine with subalpine fir on 

the more productive sites in some parts of its range (Barrett 

2008; Keane 2001b). Keane and others (1994) found that 

subalpine fir communities comprised about 12 to 22 percent 

of the landscapes in the Bob Marshall Wilderness Complex, 

but a modeling effort estimated subalpine fir abundance between 3 to 12 percent historically (Keane 2001b; Keane and 

others 1990, 1996). A similar trend is evident in the Cascade 

Mountains, where late seral species have replaced dominance by seral whitebark pine in roughly 12.5 percent of 

stands (Siderius and Murray 2005).

Whitebark pine will continue to decline as long as fire 

exclusion limits wildland fire from creating caching sites for 

the nutcracker in competition-free growing environments 

suitable for whitebark pine regeneration, and blister rust 

kills trees faster than whitebark pine can regenerate. Burning 

creates good caching habitat for Clark’s nutcrackers by exposing the ground to create a pattern-rich environment, and 

it creates optimal growing conditions for whitebark regeneration by removing its competitors (Tomback and others 

1993). Burning near areas with moderate to high levels of 

blister rust infection and mortality would favor natural selection of rust-resistant individuals because the surviving 

cone-bearing trees would likely contain rust-resistant genes 

unless nutcrackers reclaim most of their cached seed (Hoff 

and others 2001; Kendall and Keane 2001; McKinney and 

Tomback 2007; McKinney and others 2009).

Climate Change

Predicted global warming has the potential to significantly impact whitebark pine ecosystems (Bartlein and others 

1997; Romme and Turner 1991). Because of its long life 

span, whitebark pine may be a species that is able to last 

through major climatic cycles, but its complex regeneration 

processes may make it difficult to adjust to rapid climate 

change. It is speculated that increasing temperatures could 

“push” the species off the mountain by moving its lower elevational limits above the tallest peaks (Bartlein and others 

1997; Schrag and others 2008; Warwell and others 2007). 

Conventional wisdom is that less hardy, shade-tolerant 

conifer species would be able to establish in those higherelevation stands where whitebark pine currently dominates 

(Romme and Turner 1991; Koteen 1999). Bioclimatic 

envelope statistical modeling that relates climate to a 

species’ current geographical distribution has shown dramatic decreases in whitebark pine over the next 50 years 

(Figure 1.23) (McDermid and Smith 2008; Warwell and 

others 2007). However, recent modeling efforts have shown 

that whitebark pine might be maintained on the landscape 

if increases in large, stand-replacement fires create large, 

competition-free burned areas (Loehman and others 2011). 

And, if tree dispersal enables range shifts to occur, this 

will lead to new northern distributional range (Hamann 

and Wang 2006; McKenney and others 2007). Moreover, 

whitebark pine also shows promise for being maintained 

in the northern Rockies because of high levels of genetic 

diversity (Mahalovich and Hipkins 2011; Richardson and 

others 2002a); moderate to high heritabilities in key adaptive 

traits (Mahalovich 2012); demonstrated blister rust resistance (Hoff and others 1980; Mahalovich and others 2006; 

Sneizko and others 2007); minimal inbreeding (Bower and 

Aitken 2007; Mahalovich and Hipkins 2011); and generalist 

adaptive strategies (Mahalovich 2012).

Many scientists believe that most major ecosystem 

changes caused by global climate change will be facilitated by major shifts in the disturbance regimes, which have 

already been observed in some whitebark pine ecosystems 

(Gardner and others 1996; Swetnam and Betancourt 1998). 

The current mountain pine beetle outbreaks that are killing 

more whitebark pine than historical records indicate are 

probably a result of warmer winter temperatures that facilitate expansion and establishment of beetle populations in 

the higher-elevation whitebark pine zone (Logan and others 2003; Logan and Powell 2001). Jewett (2009) found that 

the highest mortality in whitebark pine occurred on warmer, 

drier sites in the GYA, and this relationship was probably 

mediated by mountain pine beetles. A warmer climate may 

also accelerate the spread of blister rust (Koteen 1999). 

Although effects of global climate change could be severe 

for whitebark pine, they are also complex and difficult to 

predict; therefore, potential climate change effects should 

never be used as an excuse for not implementing restoration 

projects (Hobbs and Cramer 2008). Instead, climate change 

predictions could be used to guide the design, approach, and 
USDA Forest Service RMRS-GTR-279. 2012. 29

kinds of restoration activities across the range of whitebark 

pine, with different activities emphasized in some bioclimatic regions or for specific site conditions.

It is important to evaluate the effects of climate change 

on all ecological interactions and processes that influence 

whitebark pine abundance. All life stages and ecosystem 

processes should be considered; not just growth response 

(Koteen 1999), but also effects on phenological and regeneration processes, such as seed dispersal, germination, and 

ecesis (Chuine 2010; Loehle and LeBlanc 1996; Price and 

others 2001). Moreover, climate change effects should be 

evaluated at landscape scales to include shifts in disturbance 

and abiotic interactions (Gardner and others 1996). If wildland fires are expected to increase in frequency and size 

(Brown and others 2004; Keeton and others 2007; Running 

2006; Ryan 1991), then whitebark pine populations could actually increase in extent because nutcrackers disperse seeds 

into large burns more effectively than wind can disperse the 

seeds of whitebark pine’s competitors, providing there are 

sufficient seed sources left on the landscape (Tomback and 

others 1990). Bunn and others (2003) emphasized the importance of accounting for microsite variability in assessing 

whitebark pine climate change response; high-elevation microsite changes, coupled with increased fire activity, could 

increase whitebark pine regeneration and growth as climates 

change. If disturbances are predicted to increase (Flannigan 

and others 2008; Logan and Powell 2001), then disturbance 

adaptations might determine future landscape compositions 

and structures; and whitebark pine has many adaptations 

to disturbance that might allow it to remain on the highelevation landscape. Maintaining whitebark pine on the high 

mountain landscape using fire could create resilient and resistant landscapes that are critical for future conservation 

efforts and effective at sequestering carbon (Craig 2009). In 

summary, while it appears that climate change can adversely 

affect whitebark pine populations, the actual magnitude and 

direction of climate response should be evaluated at several scales, especially at the local level (Keane and others 

Figure 1.23. The decline in the range of whitebark pine over the next 50 years, as predicted from a niche modeling or 

bioclimatic species envelope modeling approach. Blue lines indicate current range and red and yellow indicate 

predicted viable range in 50 years (Warwell and others 2007).
30 USDA Forest Service RMRS-GTR-279. 2012.

2008b), and these responses should not preclude restoration 

efforts (Hobbs and Cramer 2008).

Extent of Decline

There is now no doubt that whitebark pine is declining 

across most of its range. In general, trees in the mesic, warmer portions of whitebark pine’s range are experiencing the 

greatest mortality from beetles and rust (Kendall and Keane 

2001). But even the driest, coldest parts of the range are now 

experiencing blister rust infections (Bockino 2008; Resler 

and Tomback 2008). Keane and Morgan (1994b) performed 

a comprehensive analysis to predict those areas where decline from rust is the most rapid and found little correlation 

to climate averages or geography. Keane and Arno (1993) 

found a major line of demarcation that could be approximated by the 46th N latitude, where Montana and Idaho 

whitebark pine forests north of this latitude are in the worst 

state of decline.

A number of assessments document the rapid decline 

of whitebark pine (Table 1.1). The Whitebark and Limber 

pine Information System (WLIS) database is a compilation 

of all plot data documenting the decline in whitebark and 

limber pine in the Pacific Northwest and Rocky Mountains 

(Lockman and others 2007); it has recently been improved 

and updated (http://www.fs.fed.us/r1-r4/spf/fhp/prog/programs2.html). In Montana’s Rocky Mountains, Peterson 

(1999) assessed the extensive decline of whitebark pine 

in Glacier National Park. In the Bitterroot Mountains of 

Montana, Arno and others (1993) documented that whitebark pine has migrated 200 m higher in elevation because 

of past fire suppression efforts, and Hartwell (1997) found a 

75 percent decrease in whitebark pine. In Idaho, Kegley and 

others (2001) found 23 to 44 percent mountain pine beetle 

mortality and approximately 20 percent blister rust infection 

for whitebark pine in the Selkirk Mountains.

Many have addressed the decline in the Pacific Northwest. 

Goheen and others (2002) found 44 percent of whitebark 

pine stands were healthy and 46 percent were infected with 

blister rust on the Umpqua National Forest. Ward and others (2006a) synthesized results of assessments conducted in 

Washington and Oregon (see their Appendix A) and found 

percent mortality ranged from 0 to 100 percent with an average of approximately 44 percent. By 2004, Oregon had 

experienced up to 54 percent mortality in some places with a 

wide range of infected live trees (0 to 90 percent depending 

on location) (Murray 2005). Smith and others (2008) found 

that 27 percent of whitebark pine was healthy and 73 percent was infected with blister rust in the southern Rocky 

Mountains of Canada. The infection levels decreased to 

16 percent in the central Canadian Rockies and increased 

again to about 60 percent near the northern limit of the range 

of whitebark pine in Jasper National Park. Between 1996 

and 2003/04 infection levels increased from 43 percent 

to 71 percent and mortality increased from 26 percent to 

61 percent in eight stands in Waterton Lakes National Park.

Province-wide model projections of the climatic suitability of beetle habitat in British Columbia (Carroll and others 

2006) overlaid with the range of whitebark pine indicated 

that the percentage of whitebark pine’s range at high risk to 

beetle outbreaks would double between 1981 and 2010, and 

then double again between 2001 and 2070. A GIS intersection of aerial survey data of beetle outbreaks, the range of 

whitebark pine in British Columbia (obtained from inventory data), and climate suitability projections for the normal 

period showed that, as of 2007, the number of infestations in 

previously unsuitable whitebark pine ecosystems was three 

times greater than during the previous outbreak in the 1980s. 

Field studies at eight sites and observations over other parts 

of British Columbia indicated that once mountain pine beetles infested stands, they killed between 50 to 100 percent of 

large, mature cone-bearing whitebark pine within one to four 

years of infestation initiation.

The GYA has historically had the lowest blister rust and 

mountain pine beetle infections and mortality compared 

with most of whitebark pine’s range (Jewett and others 

2011). However, recent increases in blister rust infection 

(now over 20 percent) and extensive mountain pine beetle 

mortality are now causing major declines of whitebark pine 

in the GYA (Hatala and others 2010; Hicke and Logan 2009; 

Jewett 2009).

Other Whitebark Pine Issues

Several other administrative, societal, or ecological issues in whitebark pine may be important to its restoration 

and management across its range. We discuss two major 

issues that play an important role in the restoration of whitebark pine ecosystems.

Whitebark Pine Restoration in Wilderness

In the United States, whitebark pine is most commonly 

found in remote upper subalpine sites, which, on Federal 

lands, is frequently Congressionally designated Wilderness. 

In fact, approximately 84 percent of whitebark pine occurs 

on Federal land and 48 percent occurs in designated and recommended Wilderness (Keane 2000). This latter designation 

poses challenges, both legal and philosophical, for whitebark pine restoration efforts. From a practical standpoint, 

restoration is logistically challenging in areas that have 

no roads and where motorized equipment and mechanical 

transport is prohibited. In this section, we discuss the legal 

and philosophical dilemmas to whitebark pine restoration in 

Wilderness and then suggest the role Wilderness can play in 

restoration and the most compatible methods of restoration.

The Wilderness Act, signed by President Lyndon Johnson 

in 1964, defines wilderness as, “...an area where the earth 

and its community of life are untrammeled by man retaining its primeval character and influence managed so as to 

preserve its natural conditions and generally appears to have 

been affected primarily by the forces of nature, with the 
USDA Forest Service RMRS-GTR-279. 2012. 31

Table 1.1. Summary of results from studies that documented decline of whitebark pine in the U.S. and Canada. Numbers 

in parentheses represent the mean of the given range (“NF” is National Forest and “—” indicates data unavailable).

Study 

Year

Geographic

Area

Rust Infection

(%)

Overall

Decline

(%) Sources

United States

1992 Southern Bitterroot NF — 14 Arno and others (1993)

1992 Western Montana 20-90

(61)

30-90

(51) Keane and Arno (1993)

1993 Bob Marshall Wilderness 10-99

(48)

10-80

(44) Keane and others (1994)

1995 Sundance Burn Idaho 29 — Tomback and others (1995)

1995 Eastern Cascades 27 2 Hadfield and others (1996)

1996 Bitterroot NF — 29 Hartwell and Alaback (1997)

1997 Intermountain region 2-100

(36) 1 Smith and Hoffman (1998, 2000)

2000 Selkirk Mountains 33-82

(53)

22-45

(34) Kegley and others (2001)

2000 Crater Lake NP 0-20

(12) — Murray and Rasumussen (2000, 2003)

2001 Umpqua NF 70 10 Goheen and others (2002)

2003 Western Cascades, Washington 65-84

(76)

26-53

(41) Shoal and Aubry (2004)

2003 Eastern Cascades 21-84

(48)

6-42

(16) Shoal and Aubry (2004)

2004 Medicine Bow NF 0-100

(16) — Kearns and Burns (2005)

2005 Washington, Oregon 0-100

(69)

0-89

(35)

Summary of multiple studies in Ward and 

others (2006)

2007 Oregon, Washington 5-73

(27)

1-61

(21) Shoal (2007)

2008 Mt Rainier, North Cascades 22 31 Rochefort (2008)

2008 Greater Yellowstone, Teton NP 85 70 Bockino (2008)

2008 Glacier NP 73 60 Smith and others (2008)

2008 Central Idaho — 31 Hicke and Logan (2009)

2008 Greater Yellowstone 20 —

Greater Yellowstone Whitebark Pine Monitoring Group (2008)

Canada

1997 British Columbia 0-100

(45)

0-64

(21)

Campbell (1998), Campbell and Antos 

(2003)

2001 British Columbia 11-53

(31)

2-35

(19) Zeglen (2002, 2007)

2007 Canadian Rocky Mtns 98 57 Smith and others (2008)
32 USDA Forest Service RMRS-GTR-279. 2012.

imprint of man’s work substantially unnoticeable” (Section 

2 (c) P.L. 88-577). The word “untrammeled” was chosen 

carefully by the authors of the Wilderness Act to describe 

the untamed, free will aspects of wilderness. The idea was to 

allow natural processes to prevail, to allow nature to take its 

course, without human manipulation. Howard Zahniser, the 

key author of the Wilderness Act said, “Once management 

undertakes to improve the wilderness...by manipulating natural process in the wilderness itself, the fragile wilderness 

quality of the area being managed is in jeopardy.” Based on 

this definition, any type of restoration would be considered 

“trammeling” the wilderness. However, the definition also 

states that wilderness is protected and managed to preserve 

natural conditions. If whitebark pine occurred naturally but 

is in jeopardy due to some type of human influence, should 

intensive manipulation (trammeling) be allowed in order to 

restore natural conditions? Therein lays the philosophical dilemma when interpreting the Wilderness Act.

To ensure some level of consistency in interpretation of 

the Wilderness Act and to provide guidance on philosophical 

dilemmas, Wilderness Management Policy has been developed for the Federal agencies that manage wilderness. In 

general, Forest Service policy does not allow for vegetative 

manipulation or broad-scale restoration actions in wilderness, except where the objectives cannot be met outside of 

wilderness, the loss is due to human influence, and there 

is no reasonable expectation that natural reforestation will 

occur. The following are passages from the Forest Service 

Manual that relate to the topic of whitebark pine restoration:

• FSM 2320—Introduction. “Manage wilderness to ensure 

that human influence does not impede the free play of 

natural forces or interfere with natural successions in the 

ecosystem.”

• FSM 2320.2—Objectives. 2. “Maintain wilderness in 

such a manner that ecosystems are unaffected by human 

manipulation and influences so that plants and animals 

develop and respond to natural forces.”

• 2323.5—Management of Forest Cover. “Manage forest 

cover to retain the primeval character of the environment 

and to allow natural ecological processes to operate 

freely.”

• 2323.54—Reforestation. “Allow reforestation only if 

a loss of the wilderness resource has occurred, due to 

human influence, and there is no reasonable expectation 

of natural reforestation.”

• 2323.04b states that the Chief has the authority 

to approve vegetative cover manipulation or any 

reforestation activities.

Two other sections of the Forest Service Wilderness 

Management Policy that provide direction on restoration 

of whitebark pine are fire and threatened and endangered 

species:

• 2324.2—Management of Fire. Objectives. 1. “Permit 

lightning caused fires to play, as nearly as possible, their 

natural ecological role within wilderness.”

• 2324.22—Policy. 7. “Do not use prescribed fire in 

wilderness to benefit wildlife, maintain vegetative 

types, improve forage production, or enhance other 

resource values.”

• 2323.3—Management of Wildlife and Fish. Objectives. 

3. “Provide protection for known populations and aid 

in recovery in areas of previous habitation, of Federally 

listed threatened or endangered species and their 

habitats.”

• 2323.32—Policy. 4. “Manage wilderness to protect 

known populations of Federally listed threatened 

or endangered species where necessary for their 

perpetuation and aid in their recovery in areas of 

previous habitation. When alternative areas outside of 

wilderness offer equal or better protection, take actions 

to recover threatened or endangered species outside of 

wilderness areas first.”

The National Park Service policy under National Park 

Service Management Policy 2006 is as follows:

• 6.3.1—General Policy. “The National Park Service 

will take no action that would diminish the wilderness 

eligibility of an area possessing wilderness character 

until that wilderness designation has been completed. 

All management decisions affecting wilderness will 

further apply the concept of “minimum requirement” 

for the administration of the area regardless of 

wilderness category.”

• 6.3.6—Scientific Activities in Wilderness. “The 

statutory purpose of wilderness includes scientific 

activities, and these activities are encouraged 

and permitted when consistent with the Services 

responsibilities to preserve and manage wilderness.”

• 6.3.6.2—Monitoring Wilderness Resources. “As 

appropriate, wilderness monitoring programs may 

assess physical, biological, and cultural resources and 

social impacts. Monitoring programs may also need to 

assess potential problems that may originate outside 

of wilderness to determine the nature, magnitude, and 

probable source of those impacts.”

• 6.3.7—Natural Resource Management. “The National 

Park Service recognizes that wilderness is a composite 

of resources with interrelated parts. Without natural 

resources, especially indigenous and endemic species, 

a wilderness experience would not be possible. Natural 

resources management in wilderness will include and be 

guided by a coordinated program of scientific inventory, 

monitoring, and research. The principle of nondegradation will be applied to wilderness management, 

and each wilderness area’s condition will be measured 

and assessed against its own unimpaired standard. 

Natural process will be allowed, insofar as possible, to 

shape and control wilderness ecosystems. Management 

actions, including the restoration of extirpated native 

species, the alteration of natural fire regimes, the 

control of invasive alien species, the management of 
USDA Forest Service RMRS-GTR-279. 2012. 33

endangered species, and the protection of air and water 

quality, should be attempted only when knowledge and 

tools exist to accomplish clearly articulated goals.”

Currently, the only activities related to whitebark pine 

restoration that are occurring in wilderness are monitoring 

and inventory activities, caging and collecting cones from 

blister rust-resistant trees, and allowing controlled wildfire 

to restore successionally advanced whitebark pine stands. 

Cone collection has low impacts and does not require any 

manipulation or prohibited activity, and wildfires are encouraged because they are supported by law and policy and 

have many resource benefits. Other activities that have been 

suggested but not implemented are planting of putatively 

blister rust-resistant seedlings, sowing blister rust-resistant 

seeds, mechanical thinning, and prescribed fire. All of these 

activities involve manipulation that would typically not be 

allowed in wilderness. Prior to any of these activities being 

implemented, the following steps must be taken:

• Determine that the loss of whitebark pine is due, in fact, 

to human intervention.

• Determine that restoration objectives cannot be 

accomplished entirely outside of wilderness.

• Determine if there is a reasonable expectation 

that human intervention will result in a significant 

improvement in whitebark pine survival.

• Determine if the analysis has proven that whitebark 

pine restoration actions are the minimum requirement 

or minimum tool necessary to meet the objectives.

• Determine the adverse effects of restoration actions 

on the other qualities of wilderness character 

(untrammeled, undeveloped, and outstanding 

opportunities).

• Determine if the timing, frequency, location, or 

intensity of the restoration actions can be altered to 

mitigate these adverse effects.

• Determine if the activity can be accomplished without 

the support of motorized equipment or mechanical 

transport.

If the project passes these tests, a National Environmental 

Policy Act environmental assessment and analysis will need 

to be completed, including public scoping.

One major restoration activity that is specifically excluded by policy from Forest Service Wilderness Areas is tree 

planting, and especially planting rust-resistant whitebark 

pine seedlings. Keane and Parsons (2010a) have found that 

planting whitebark pine seedlings in areas of high mortality 

of mature, seed-producing tree mortality may be essential 

for preventing local extirpation. On the other hand, Landres 

(2010) presented a rationale for taking a “hands off” approach to restoration and allowing whitebark pine to further 

decline. Since nearly half of whitebark pine’s range occurs 

in wilderness or protected settings, the ability to plant seedlings or seed may have vast implications to the success of 

range-wide restoration strategies.

Conservation Efforts for Whitebark Pine

At this time, the effects of cumulative losses of whitebark pine are gaining recognition, particularly after the 

massive mountain pine beetle outbreaks of the past decade 

coupled with increasing damage and mortality from white 

pine blister rust. The decline of whitebark pine and other impacted five-needle white pines was brought to the attention 

of the Chief of the U.S. Forest Service through the reports, 

“Managing for Healthy White Pine Ecosystems in the United 

States to Reduce the Impacts of White Pine Blister Rust” 

(Samman and others 2003), and “Whitebark Pine in Peril: A 

Case for Restoration” (Schwandt 2006). More recent efforts 

to highlight the decline in five-needle white pines include: 

the publication of a special issue of “Forest Pathology” in 

2010 on white pine blister rust, edited by C. G. Shaw and 

B. W. Geils, and the 2010 conference and proceedings “The 

High Five Symposium: The Future of High-Elevation FiveNeedle White Pines in Western North America,” organized 

by the Whitebark Pine Ecosystem Foundation, a 501 (c) 3 

non-profit group dedicated to the restoration of whitebark 

pine (Keane and others 2011). Finally, whitebark pine 

achieved national media attention upon announcement in 

July, 2011, that it was listed as a candidate species under 

the Endangered Species Act (U.S. Fish and Wildlife Service 

2011a, 2011b). This is the first widely distributed forest tree 

in the United States to warrant listing.

The status of whitebark pine is continually being evaluated at national, state, and provincial levels. First of all, 

whitebark pine is categorized as vulnerable (high risk of 

extinction in the wild in the medium-term future) both on 

the global IUCN Red and NatureServe List (IUCN 2007; 

NatureServe 2009). In the United States, whitebark pine 

was listed as a Species of Concern in western Washington 

in 2004 and in eastern Washington in 2009 by the U.S. Fish 

and Wildlife Service (2007, 2009). In December 2008, the 

Natural Resources Defense Council (2008), a U.S. nonprofit, tax-exempt organization, submitted a petition to the 

U.S. Fish and Wildlife Service to list whitebark pine as an 

Endangered Species under the Federal Endangered Species 

Act. The 12-month finding (previously mentioned) concluded that listing was in fact warranted, but current listing 

was precluded by “higher priority actions to amend the Lists 

of Endangered and Threatened Wildlife and Plants” (U.S. 

Fish and Wildlife Service 2011b). The finding further stated 

that “We will develop a proposed rule to list P. albicaulis as 

our priorities and funding will allow.” Whitebark pine has 

been added to the candidate species list and waits updating 

through the annual Candidate Notice of Review.

The Committee on the Status of Endangered Wildlife 

in Canada (COSEWIC) has recommended that whitebark 

pine be Federally listed as Endangered under the Species 

at Risk Act (SARA) in Canada. In Alberta, whitebark pine 

was recently listed as an Endangered Species under The 

Wildlife Act because of ongoing and projected population 

declines in the province and because the status of neighboring populations in Montana and British Columbia, which 
34 USDA Forest Service RMRS-GTR-279. 2012.

are also declining due to blister rust infections and mountain 

pine beetle outbreaks, reduce the likelihood of population 

“rescue” through seed dispersal to Alberta by the Clark’s 

nutcracker. This listing provides legal protection for whitebark pine in Alberta and necessitates the development of a 

recovery strategy for the species.

In 2007, the Conservation Data Centre at the British 

Columbia Ministry of the Environment added whitebark 

pine to its Blue List. Species on the Blue List are of special 

concern because of characteristics that make them particularly sensitive to human activities or natural disturbance 

events. Whitebark pine was added to this list because most 

populations are infected by the exotic blister rust fungus; a 

significant proportion of mature forests are now being killed 

by a mountain pine beetle outbreak; and a severe decline 

(70 to 90 percent) is expected over the next 70 years due to 

expanding mountain pine beetle outbreaks, continued blister 

rust infections, fire protection activities that facilitate successional replacement, climate change, and increased pressure 

to log subalpine forests. While adding whitebark pine to the 

Blue List does not confer legal protection, it does highlight 

the species for more formal designation as a Threatened (or 

Endangered) species, either provincially under the British 

Columbia Wildlife Act, or nationally by the COSEWIC. 

It also calls attention to the species for special consideration under Operational Planning Regulations in the Forest 

Practices Code of British Columbia Act, and forest professionals in British Columbia are beginning to help conserve 

whitebark pine by making minor adjustments to landscapelevel forest stewardship plans as well as harvesting and site 

plans (for example, adjustment of cutblock boundaries).
USDA Forest Service RMRS-GTR-279. 2012. 35

The Strategy

The range-wide whitebark pine restoration strategy consists of a set of principles coupled with associated actions to 

guide the design, planning, and implementation of restoration 

activities throughout the range of whitebark pine (Schoettle 

and Sniezko 2007; Schwandt 2006) (Figure 2.1). The guiding principles represent broad areas of emphasis that need 

to be addressed when restoring whitebark pine. They were 

taken from a number of sources and represent the most current research in whitebark pine conservation (Aubry and 

others 2008a; Elderd and others 2008; Fins and others 2001; 

McKinney 2004; McKinney and others 2009; Schoettle and 

Sniezko 2007; Schultz 1989; Schwandt and others 2006; 

Sniezko and others 2004; Waring and O’Hara 2005):

1. Promote rust resistance. The most important action 

in restoring whitebark pine is to ensure that future 

populations of the species have some resistance to blister 

rust by increasing the frequency of trees with genetic 

resistance to the blister rust pathogen. All restoration 

plans and activities must first address how natural or 

planted whitebark pine regeneration will survive with 

blister rust, now a naturalized species in North America 

(Geils and others 2010). To accomplish this, managers 

must (a) support selective breeding programs to develop 

and deploy blister rust-resistant whitebark pine, (b) 

facilitate and accelerate natural selection for blister rustresistant genotypes in stands by reducing competition to 

increase survival of healthy putative rust-resistant trees 

in high blister rust areas, providing openings for natural 

seed dispersal and seedling survival, and (c) plant 

seedlings from trees known to have some level of blister 

rust resistance.

2. Conserve genetic diversity. The full genetic diversity 

across the range of whitebark pine must be preserved for 

the future by collecting and archiving seeds and growing 

and planting genetically diverse seedlings. During the 

process of selecting rust-resistant lineages for growing 

seedlings and planting, we must be careful not to lose 

the broad genetic diversity inherent in the species. Other 

2. Whitebark Pine Restoration Strategy

Figure 2.1. The range-wide 

restoration strategy.
36 USDA Forest Service RMRS-GTR-279. 2012.

critical activities include archiving pollen; developing 

seed orchards to produce blister rust-resistant seeds; 

and establishing clone banks to archive the selections 

possessing desirable characteristics of blister rust 

resistance, cold hardiness, and mountain pine beetle 

tolerance.

3. Save seed sources. Mature, seed-producing, putatively 

rust-resistant whitebark pine trees in regions that are 

experiencing rapid decline must be protected from 

other native or exotic disturbances so that the apparent 

rust-resistant seeds can be harvested in the future. These 

disturbances include bark beetles, unwanted wildland 

fire, and timber cutting. Identification and prioritization 

of areas that contain rust-resistant and genetically diverse 

trees can be accomplished with comprehensive genetics 

profiles using data generated from regional genetics 

programs and collaborative partnerships with research.

4. Employ restoration treatments. Areas where whitebark 

pine forests are declining due to insects, disease, 

or advanced succession should be considered for 

restoration treatments to create sustainable whitebark 

pine populations. Proactive restoration includes 

managing to limit the spread of blister rust; using fire 

in successional advanced communities to encourage 

whitebark pine regeneration; implementing silvicultural 

cuttings to reduce competing vegetation to increase 

the vigor of surviving trees and reduce the likelihood 

of mountain pine beetle attacks; planting rust-resistant 

seedlings to accelerate the effects of selection; and 

promoting natural regeneration and diverse age class 

structures to maintain ecosystem function and reduce 

landscape level beetle hazard, and to provide large 

populations for selection for rust resistance.

These principles are used to guide whitebark pine restoration 

plans at various spatial scales in conjunction with the following set of possible actions. One or more of these actions 

constitute meaningful steps toward restoring whitebark pine 

ecosystems.

1. Assess condition. Conduct assessments that document 

the status and trend of whitebark pine within regions. 

This includes inventory and monitoring projects, GIS 

mapping and modeling, and remote sensing applications.

2. Plan activities. Design plans and possible treatments 

for restoring whitebark pine ecosystems. This includes 

prioritizing, locating, and scheduling areas to treat.

3. Reduce disturbance impacts. Implement proactive 

measures to reduce the risk of blister rust, mountain pine 

beetle, and other disturbance impacts on whitebark pine 

forests. This may include Ribes spp. removal, pruning 

branches with cankers, spraying fungicide or insecticide, 

thinning, and treating fuels around rust-resistant trees to 

reduce wildfire-caused mortality.

4. Gather seeds. Collect seeds from trees that are proven 

rust-resistant or phenotypically rust-resistant in areas 

exposed to blister rust, and from trees not tested in 

areas yet to be exposed to blister rust for archiving 

genetic diversity and variation. These seeds can be 

used for operational planting, and possibly for direct 

seeding. Seed collections should be made throughout 

the distributional range of whitebark pine to capture the 

range of genetic diversity before it is reduced by the 

threats to whitebark pine. Seed inventories should be 

managed and periodically assessed for seed viability 

and to ensure that effective population sizes are being 

maintained in space and time. This will enable agencies 

to be proactive in conservation and to provide a buffer 

for climate change.

5. Grow seedlings. Grow whitebark pine seedlings from 

seeds of proven (genetically tested in a rust screening) 

rust-resistant trees; document levels of rust resistance 

performance in the parent trees and their seedlings; 

and establish seed orchards, and plant their seedlings 

in areas that have been treated with the appropriate site 

prescriptions.

6. Protect seed sources. Protect valuable rust-resistant, 

seed-producing whitebark pine from future mortality 

caused by disturbance, climate change, and competition.

7. Implement treatments. Create conditions that 

encourage whitebark pine regeneration, conserve seed 

sources, and promote rust resistance. This includes 

creating nutcracker caching habitat, reducing competing 

vegetation, and decreasing surface and canopy fuels 

using direct or indirect treatments, manipulating forest 

composition, and diversifying age-class structure.

8. Plant seedlings. Plant rust-resistant seedlings or sow 

seeds directly in treated or burned areas, especially in 

areas experiencing heavy whitebark pine mortality. 

Areas with few whitebark pine seed sources will 

doubtfully produce enough seed to provide for 

nutcracker energy requirements and adequate whitebark 

pine regeneration. Because blister rust is at the northern 

periphery and elevational limits of whitebark pine’s 

range, which are important climate change fronts, 

seedlings should be planted from rust-resistant parent 

trees at both the elevational and northern limits.

9. Monitor activities. Pre- and post-activity field sampling 

is critical to document the success or failure of 

restoration treatments. Limited research funding will 

preclude extensive assessments of novel restoration 

treatments and activities, so monitoring will play an 

important role in providing critical information on the 

efficacy of restoration approaches. Install, maintain, 

and collect periodic data in replicated long-term genetic 

tests to assess the durability of rust resistance under 

operational conditions and natural inoculums; measure 

adaptive traits on older seedlings; and periodically 

reassess seed transfer guidelines and seed source 

performance under changing climatic conditions.
USDA Forest Service RMRS-GTR-279. 2012. 37

10. Conduct research. Researchers must continuously 

develop new and more efficient methods and techniques 

for identifying blister rust-resistant parent trees, thinning 

successionally advanced stands, growing seedlings, 

planting seeds and seedlings, and collecting cones. 

Development of genomic techniques for rapid testing 

of trees for genetic resistance would save years of 

greenhouse work and would make proactive restoration 

planning far easier and less costly. Research should seek 

to improve the restoration process by providing vital 

information on state-of-the-art techniques and protocols 

that will hopefully make restoration efforts more 

effective and cheaper.

This restoration strategy and its associated actions are 

discussed at six spatial scales of analysis (Figure 2.2) (Keane 

and others 1996): (1) whitebark pine’s entire range (coarsest scale); (2) regional scale using the U.S. Forest Service 

Pacific Northwest and Northern Regions as examples; (3) 

forest scale that is equivalent in size to National Forests and 

National Parks; (4) landscape scale, which could be watersheds, management units, or landforms; (5) stand scale 

where most proactive restoration activities take place; and 

(6) tree level where intensive treatments are needed to protect individual whitebark pines. At each scale, we detail four 

important factors in the restoration strategy:

• Assessments—We present various assessments that 

can be used to prioritize restoration treatments. These 

factors describe ownership concerns (wilderness and 

land management agency, for example), ecosystem 

characteristics (successional stage and threatened 

species), and whitebark pine decline (percent rust 

infection and percent mortality).

• Restoration Actions—We present a set of possible 

tools, treatments, and management actions that can be 

conducted at the landscape and tree scale to restore 

whitebark pine ecosystems.

• Management Concerns—We detail important issues, 

barriers, and limitations facing land management for the 

restoration actions.

• Examples—An example or actual implementation of 

an aspect of the restoration strategy for that scale is 

included. Actual restoration plans are presented for 

the coarse-scale strategies, while illustrated examples 

are presented for the finer-scales (tree, stand, and 

landscape). We provided summaries of regional, broadarea, and National Forest strategies. The finer-scale 

examples can be repeated for other areas within the 

range of whitebark pine.

This strategy and the details of its implementation were 

integrated from a number of sources and are based on the 

Figure 2.2. The six scales implemented in 

this whitebark pine restoration strategy.
38 USDA Forest Service RMRS-GTR-279. 2012.

latest research and perspectives. This strategy also emphasizes the importance of enhancing rust resistance on the 

landscape based on a number of foundation documents 

(Burns and others 2007, 2008; Fins and others 2001; Hoff 

and others 2001; Keane and Arno 2001; Schwandt and others 2006; Schoettle and Sniezko 2007). Several restoration 

plans for regional and local implementation also provided 

information used here (Aubry and others 2008; Jenkins 

2005; Peterson 1999; Wilson and Stuart-Smith 2001). In the 

next section, we detail important restoration concepts that 

provide background for this strategy.

Important Restoration Concepts

The range-wide whitebark pine restoration strategy is 

built on some important concepts that were used to provide 

the foundation and context. First, we assume that because 

whitebark pine’s decline is due to an exotic disease, proactive 

management is needed to ensure that whitebark pine is sustained on future landscapes and restoration should be based 

on credible science (Hobbs and Cramer 2008). Some people 

question the need for active restoration management, especially in ecosystems with exotic introductions (Higgs 1997) 

or wilderness settings (Landres 2010), but we feel that both 

“reactive” restoration to current conditions and proactive 

restoration in anticipation of losses are critical for long-term 

whitebark pine conservation (Schoettle and Sniezko 2007; 

Sniezko and others 2004). Others suggest a trial-and-error or 

“tinkering” approach over scientific evidence (Cabin 2007), 

but we feel that restoration treatments based on the most current scientific information will have the greatest success and 

will be the most efficient. Schoettle and Sniezko (2007) presented five proactive options for sustaining high-elevation 

five-needle pine ecosystems threatened by blister rust that 

overlap with the restoration steps presented above: (1) reduce pest populations, (2) manage forest composition, (3) 

increase host vigor, (4) plant rust-resistant seedlings, and (5) 

diversify age classes (also see Keane and Schoettle 2011). 

The role of whitebark pine as a keystone species becomes 

increasingly important as whitebark pine becomes more 

dominant within stands; and thus whitebark pine communities have a higher value than stands that have whitebark pine 

as a minor component. Therefore, restoration efforts should 

concentrate on restoring forest communities and not just the 

species.

Historical Range and Variability

This range-wide strategy is primarily based on the notion that historical conditions provide the most appropriate 

reference for comparing and assessing whitebark pine status, 

and historical conditions provide important sideboards and 

targets for designing and implementing restoration treatments. Historical ecology is used to guide many restoration 

efforts (Egan and Howell 2001; Perera and others 2004), 

and the concept of Historical Range and Variability (HRV) 

is often used to implement historical ecology into restoration 

planning (Apfelbaum and Chapman 1997; Landres and others 1999; Morgan and others 1994a). HRV is the broad 

historical envelope of possible ecosystem conditions or 

characteristics, such as fire regime, vegetation cover type 

area, or patch size distribution that provides a representative span of reference conditions to guide land management 

(Landres and others 1999).

This range-wide strategy assumes that the goal of any 

restoration treatment or policy is to maintain whitebark pine 

forests within their historical range. Some feel that HRV 

will no longer be a viable concept in the future because of 

expected climate warming and expanding human activities 

across the landscape (Millar and others 2007). However, we 

feel at this time that past climates and ecosystem conditions 

represent considerably less uncertainty than do future predictions of climate and ecosystem response; therefore, HRV 

represents the best possible reference for guiding restoration 

in the near term until ecosystem simulation technologies improve and more reliable climate forecasts become available 

(Keane and others 2009). In fact, large variations in climate 

over the past several centuries are already represented in 

many HRV time series. In the meantime, it is doubtful that 

the use of HRV to guide management efforts will result in 

inappropriate activities considering the great genetic variation within most species, especially whitebark pine) (Davis 

and others 2005; Rehfeldt and others 1999), the longevity 

of whitebark pine (Arno and Hoff 1989), and the robustness 

inherent in regional landscapes that display the broad range 

of conditions in HRV projections (Keane and others 2009). 

Restoration plans can be changed as simulation technology 

improves and as more knowledge becomes available. When 

ecosystem models have sufficient reliability to generate future trajectories of whitebark pine populations, we suggest a 

melding of HRV with the future range of variability (FRV) 

to assess if management actions are outside the envelope of 

both the past and future conditions (Keane and others 2009).

Physiological Constraints

Another restoration foundation concept is that conservation efforts incorporate adaptation and physiological 

limitations into their design. The idea of conservation 

physiology specifically addresses a species’ physiological response to the changing environment and disturbance regimes 

(Wikelski and Cooke 2006). In short, we must know the tolerance limits for all phases of whitebark pine’s life cycle for 

any restoration plan to be effective (for a simple example, 

don’t plant whitebark pine seedlings where they cannot grow) 

(Cooke and Suski 2008). This seems in conflict with the 

HRV concept and global climate change, but we emphasize 

that this physiological approach can be better guided by the 

HRV of the species range and distribution than any prediction of global climate change environments with biophysical 

envelop modeling (for example, Warwell and others 2007). 

Ecophysiological constraints identified from new research 

can be addressed as climate changes in the future to provide a 

basis for conserving these high-elevation ecosystems.
USDA Forest Service RMRS-GTR-279. 2012. 39

Assembly Rules

Last, we base this strategy on the idea of “assembly rules” 

in restoration ecology (Temperton and others 2004). The 

species composition of ecosystems is shaped by interactions 

among species, including pests and diseases, mutualists 

and competitors, physical disturbance factors, climate, and 

multiple abiotic factors (soils, for example) (Wilson and 

others 1996). It is important to include these interactions 

in restoration designs to ensure that restored ecosystems 

are sustainable in the future (Luh and Pimm 1993). For example, proactive restoration treatments for whitebark pine 

should include prescribed burning to emulate the effects 

of historical disturbance where geographically appropriate (Keane 2001a; Murray and others 1997). Given that the 

blister rust pathogen is now well-integrated into our western 

mountain ecosystems and that future warming trends are 

predicted, the assembly rules approach to whitebark pine 

restoration entails planting rust-resistant seedlings and even 

planting seedlings from lower latitudes (Funk and others 

2008). This strategy, if supported by geo-climatic analyses 

of genetic data where blister rust resistance is one of the key 

adaptive traits, would ensure that whitebark pine survives 

into the future (Bradley and Pregitzer 2008).

Proactive Approach

Not all whitebark pine ecosystems have been invaded 

by white pine blister rust, though all are vulnerable to impacts. There is an opportunity with proactive management 

to enhance currently healthy ecosystems to retain ecosystem function during the naturalization process of the rust 

(Schoettle and Sniezko 2007). The goal of proactive intervention in these ecosystems is to increase resiliency and 

sustainability of ecosystem functions in the presence of the 

spreading rust and other threats such that ecosystem impairment in the future is mitigated (Schoettle and Sniezko 2007). 

Healthy, functional ecosystems are better able to respond to 

management than heavily impacted ecosystems. Therefore, 

more management options are available and the potential 

for a successful outcome is improved. We know that blister 

rust can kill trees of all ages and disease impacts the regeneration capacity of pine populations (Schoettle and Sniezko 

2007). As a result, efforts to stimulate regeneration after 

the population is heavily impacted may be compromised 

due to seed and disperser limitations (Keane and Parsons 

2010b; McKinney and others 2009). Interventions in healthy 

ecosystems can avoid possible regeneration failure that constrain management options and affect outcomes. Sometimes 

waiting for populations to be impacted before acting is not 

advisable.

Promoting early selection and establishment of resistant genotypes provides time for the resistant seedlings to 

mature to seed-bearing age before high mortality occurs 

in the mature susceptible trees, thereby reducing the time 

where the ecosystem’s recovery capacity is compromised. 

Three approaches, two at the stand scale and one at the landscape scale, have been developed to proactively facilitate an 

increase in rust resistance and mitigate the impact of the mortality of rust-susceptible trees (Schoettle and Sniezko 2007). 

Stimulating natural regeneration can increase population 

size, multiply genetic combinations, and promote efficient 

selection for resistance in the younger cohorts when rust arrives. Additionally, planting rust-resistant seedlings before 

rust has impacted an area can directly introduce rust-resistant genotypes to the population. Diversifying the age class 

structure across the landscape will also result in rust resistance selection (mortality of susceptible pines) proceeding 

at different rates in different patches that ultimately reduces 

the impact of mortality in any one cohort on ecosystem services. A mosaic of stand structures and ages positions the 

ecosystem for rapid and efficient natural selection for resistance in the younger cohort while the older cohort sustains 

ecosystem function (Schoettle 2004). A structurally diverse 

landscape is also more resilient to mountain pine beetle impacts and has greater adaptive capacity to climate change. To 

conduct these interventions requires resources and processlevel information on how these little-studied ecosystems 

respond to perturbation.

Unique opportunities and challenges face researchers 

and land managers interested in proactively increasing the 

resiliency of whitebark pine ecosystems, including the need 

to: (1) educate and engage the public and managers to manage for resiliency, (2) conserve genetic diversity from native 

populations before they are impacted by rust and other 

stresses, (3) research patterns, processes, and responses of 

native ecosystems to provide process-level understanding of 

ecosystem behavior, and (4) develop and implement management actions that increase the resiliency of whitebark 

pine ecosystems to prepare them for change.

Central Tenets of the Restoration Strategy

Here, we describe three central tenets upon which the 

implementation of restoration treatments presented in this 

plan are based, listed in order of importance:

1. Lands having high blister rust infection and mortality 

have the highest priority for restoration. This is a 

result of a number of factors, including the following 

(Schwandt 2006):

a. Whitebark pine populations are the lowest in these 

areas because of decades of decline (Kendall and 

Keane 2001; McKinney and others 2009).

b. There may be a higher frequency of rust-resistant 

seeds in these areas because rust has likely killed 

most of the trees that were highly susceptible to the 

rust (Hoff and others 2001).

c. There may be a lower potential for these areas to 

naturally regenerate to whitebark pine (McKinney 

and Tomback 2007; McKinney and others 2009; 

Tomback 2008).

2. Lands having high mountain pine beetle mortality have 

a higher priority for restoration (Perkins and Roberts 

2003; Six and Adams 2007). This is because:
40 USDA Forest Service RMRS-GTR-279. 2012.

a. Potentially rust-resistant, cone-bearing whitebark pine 

trees will be killed by the beetles.

b. Mountain pine beetle mortality, coupled with rust 

mortality and fire exclusion effects, will exacerbate 

the decline of the whitebark pine ecosystem (Six and 

Adams 2007).

c. Seed dispersal will be limited because there will be 

fewer whitebark pine cone-bearing trees (McKinney 

and Tomback 2007; McKinney and others 2009; 

Tomback 2008).

3. Lands that are in the later stages of successional 

development have a higher priority for restoration

(Keane 2001b; Keane and Arno 2001). Whitebark pine 

mortality and cone loss from these stands are the highest 

because:

a. These are the stands where whitebark pine occurs in 

low densities with low vigor because of increased 

competition from shade-tolerant associates.

b. Most mature whitebark pine trees are dying or dead 

from competition, fire, insect, and disease.

c. Many surviving, mature whitebark pine suffer high 

rates of red squirrel cone predation (McKinney and 

Fiedler 2010).

In areas where blister rust and mountain pine beetle are at 

low levels (causing sporadic damage and mortality), it may 

also be considered prudent to begin proactive restoration 

work. This work (Schoettle and Sniezko 2007) entails:

1. Managing the spread of blister rust by controlling 

alternate hosts, usually Ribes spp. (care should be taken 

to limit Ribes spp. increases from disturbance) (see 

Tomback and Achuff 2010).

2. Screening accessible, healthy trees in search of blister 

rust-resistant parent trees.

3. Thinning or using fire in successional advanced 

communities to encourage whitebark pine regeneration, 

which provides selection opportunities.

4. Thinning and reducing competing vegetation to increase 

the vigor of trees and reduce the likelihood of mountain 

pine beetle attacks.

5. Planting rust-resistant seedlings from local trees to 

accelerate the effects of selection.

6. Promoting natural regeneration and diverse age class 

structures to maintain ecosystem function and provide 

large populations for selection for rust resistance.
USDA Forest Service RMRS-GTR-279. 2012. 41

Government natural resource agencies are responding to 

the widespread degradation of natural ecosystems and watersheds, losses of biodiversity, and declining ecosystem 

function by engaging in strategic planning to mitigate the 

effects as efficiently and strategically as possible. Ecosystem 

degradation is often a result of a number of widely different 

anthropogenic factors, such as altered natural disturbance 

regimes, habitat destruction, fragmentation, invasive species, loss of natural buffer zones, and climate change. The 

varied causes and consequences of anthropogenic activities 

complicate management plans, especially a range-wide restoration strategy such as that detailed in this report. Below 

are the directions of two Government sources—U.S. Forest 

Service and Canadian land management agencies—for conducting nationwide restoration activities to preserve critical 

upper subalpine ecosystems. These directives set the context 

for many of the details of this restoration strategy for whitebark pine.

U.S. Forest Service

The U.S. Forest Service created an Executive Integration 

Team that chartered a Restoration Framework Team to develop “a strategic, integrated, science-based framework for 

restoring and maintaining forest and grassland ecological 

condition” across the United States (Day and others 2006). 

Under this charter, a restoration framework team recognized 

that the nation’s forests and grasslands face serious threats to 

their long-term health, productivity, and diversity. Foremost 

are non-native invasive species, altered disturbance regimes, 

and climate change. These diverse threats affect aquatic and 

terrestrial ecosystems in virtually every region of the country. 

Agency and public concern about some of these threats has 

led to the National Fire Plan (http://www.fs.fed.us/r1/pgr/

afterfire/nfp.html), Healthy Forests Initiative and Healthy 

Forests Restoration Act (http://www.fs.fed.us/projects/hfi/), 

Invasive Species Strategy (http://www.invasivespeciesinfo.

gov/toolkit/controlus.shtml), and various administrative actions to help facilitate restoration actions. Nevertheless, the 

magnitude of ecosystem restoration needs appears to greatly 

exceed the organizational and financial capacity of the agency. Many forest and grassland ecosystems, such as whitebark 

pine, continue to degrade at a rate that can be mitigated by 

restoration actions. The Forest Service must improve its productivity and effectiveness to achieve restoration objectives. 

New approaches are needed to clarify and focus the agency’s 

policy for ecosystem restoration.

This framework offers recommendations to improve the 

agency’s ability to restore ecosystems (Day and others 2006):

• Adopt a national policy regarding ecosystem restoration, 

including defining ecosystem restoration as “the process 

of assisting the recovery of an ecosystem that has been 

degraded, damaged, or destroyed.”

• Increase productivity of the agency’s restoration efforts 

through improved integration of various programs 

spanning all deputy areas.

• Effectively apply national, forest, and project planning 

to engage Forest Service resources, partners, and 

stakeholders in identifying and implementing restoration 

needs and priorities.

• Use budget and performance incentives to increase 

accomplishment of ecosystem restoration objectives.

Protection of valuable resources and restoration of severely degraded areas were the primary reasons for creating 

the Forest Service and establishing the National Forests and 

Grasslands. Day and others (2006) stated that implementing the recommendations in this Framework will greatly 

strengthen the agency’s ability to fulfill its mission of sustaining “the health, productivity, and diversity of the nation’s 

forests and grasslands to meet the needs of present and future generations.” The following are the goals of the national 

strategy:

1. Reduce the risk from catastrophic wildland fire. Restore 

the health of the nation’s forests and grasslands to 

increase resilience to the effects of wildland fire.

2. Reduce the impacts from invasive species. Restore 

the health of the nation’s forests and grasslands to be 

resilient to the effects of invasive insects, pathogens, 

plants, and pests.

3. Provide outdoor recreational opportunities. Provide highquality outdoor recreational opportunities on forests and 

grasslands, while sustaining natural resources, to meet 

the nation’s recreational demands.

4. Help meet energy resource needs. Contribute to meeting 

the nation’s energy need.

5. Improve watershed condition. Increase the number 

of forest and grassland watersheds that are in fully 

functional hydrologic condition.

6. Conduct mission-related work in addition to that which 

supports the agency goals. Conduct research and other 

mission-related work to fulfill statutory stewardship and 

assistance requirements.

The establishment of the Sustainable Land Management 

Board of Directors (SLMBOD) and their “Restoration and 

Maintenance” performance measures was intended as an incentive for integrated ecosystem restoration project planning 

and implementation by allowing line officers to justify higher unit cost for program-specific outputs when the project 

3. National and Regional Direction
42 USDA Forest Service RMRS-GTR-279. 2012.

results in multiple, reportable outcomes meeting a wide 

range of established desired condition objectives. Under the 

direction of the SLMBOD, the Forest Service developed a 

national strategy for restoration and maintenance of ecosystems with the objective to re-establish and retain ecological 

resilience of National Forest System lands and associated 

resources to achieve sustainable management and to provide 

a broad range of ecosystem services. Intact, resilient landscapes will have greater capacity to respond to and survive 

natural disturbances and large-scale threats to sustainability, 

especially under changing and uncertain future environmental condition, such as those driven by climate change and 

increasing human use.

Chapter 10 of the Fiscal Year 2009 Initial Program 

Direction includes guidance regarding the establishment 

of a single performance measure and target. The Program 

Direction recognizes that ecological restoration and maintenance to achieve sustainable landscapes requires an 

integrated approach, including restoration of water quality 

and watershed processes, vegetative condition, air quality, 

and fish and wildlife populations. During this initial effort 

to establish and define this new performance measure, the 

focus is on integrated terrestrial vegetation management designed to meet ecosystem restoration objectives.

U.S. National Park Service

The National Park Service (NPS) administers a broad 

range of programs that serve the conservation and recreation 

needs of the National Park System. Management Policies 

(USDI NPS 2006) is the basic service-wide document to 

guide management to preserve, unimpaired, the natural and 

cultural resources and values of the National Park System 

for the enjoyment, education, and inspiration of this and future generations.

Restoration of natural ecosystems is a tenet of NPS management policies. The NPS strives to understand, maintain, 

restore, and protect the inherent integrity of park resources, 

processes, systems, and values. This includes re-establishing 

natural functions and processes that have been damaged or 

compromised in the past. Landscapes that have been disturbed by natural phenomena such as landslides, hurricanes, 

and fires will be allowed to recover naturally. Impacts on 

natural systems resulting from human disturbances include 

introduction of nonnative species; contamination of air, water, and soil; changes to hydrologic patterns and sediment 

transport; and disruption of natural processes. The NPS will 

seek to return disturbed areas to natural conditions and processes. Examples of restoration efforts are:

• removal of exotic species,

• restoration of abandoned mineral lands, roads, or 

disrupted waterways,

• restoration of natural soundscapes or visibility, and

• restoration of native plants and animals.

Canadian Land Management Agencies

There is no national direction in Canada regarding the 

conservation or restoration of whitebark pine or whitebark 

pine ecosystems, which occur almost entirely on public 

Crown Lands, including provincial protected areas such as 

provincial parks, ecological reserves, wildlife management 

areas, and wilderness areas. The provinces of Alberta and 

British Columbia have slightly different management mandates and legislation. Therefore, any restoration direction 

is specified at the provincial level for Alberta and British 

Columbia.

British Columbia

In British Columbia, the Ministry of Environment’s 

Conservation Framework provides a set of decision support tools to enable collaboration between government and 

non-government resource managers and practitioners using 

defined criteria: (1) to prioritize species and ecosystems 

for conservation; and (2) to determine the most appropriate and effective management actions, including ecosystem 

and habitat protection and restoration, stewardship, and species and population management. The Ministry of Forests 

Ecosystem Classification system is used to delineate ecosystems that may cross administrative boundaries such 

as British Columbia Forest Service Region and district 

boundaries. The conservation framework provides a decision key for reassigning status ranks (assignment to the 

British Columbia Red List means that the species is extirpated, endangered, or threatened, and assignment to the Blue 

List means that the species and ecosystems are of special 

concern) based on new information; initiating a provincial 

and/or Federal legal listing process; starting a full recovery/

restoration planning process; and initiating on-the-ground 

protection measures. In most instances, species and ecosystems are formally listed under the provincial Wildlife Act 

and the Federal Species At Risk Act (SARA) before on-theground restoration actions are formally implemented with 

provincial-level guidance.

A recovery and restoration process and plan would become mandatory if whitebark pine was moved to British 

Columbia’s Red List, and prioritization of activities would 

be undertaken at the provincial level. The Ministry of 

Environment published a document on guidelines for 

ecological restoration on public and private lands. This document lays out the philosophy of ecological restoration and 

provides general guidelines for setting restoration goals and 

objectives, setting restoration priorities, and planning restoration projects. There is not yet a formal province-wide 

restoration plan for whitebark pine, but several conservation 

actions have been initiated:

• A provincial inventory of whitebark pine and its 

communities has been completed.

• Province-wide surveys of blister rust infections and 

mountain pine beetle infestation have been undertaken.
USDA Forest Service RMRS-GTR-279. 2012. 43

• The British Columbia Ministry of Forests in 

collaboration with the Canadian Forest Service and 

the University of British Columbia produced first 

approximation projections of climate change impacts 

on whitebark pine, including climate change impacts on 

disturbance (Carroll and others 2006; Hamann and Wang 

2006).

• The British Columbia Conservation Data Centre 

added whitebark pine to its Blue List in 2007 with the 

justification that although the species currently occurs 

in relatively high numbers over a fairly large range in 

the province, major declines of 75 to 90 percent are 

expected “due to a severe negative long-term trend 

expected from mountain pine beetle infections, the white 

pine blister rust epidemics, climatic warming trends, and 

successional replacement.”

• Following the British Columbia assessment, the Deputy 

Chief Forester for the British Columbia Ministry of 

Forests and Range issued a letter asking resource 

managers and forest professionals to take voluntary 

measures to conserve whitebark pine during forestry 

activities by considering the species in planning and 

operational activities.

• The British Columbia Ministry of Forests has surveyed 

in situ protection of all tree species in British Columbia 

protected areas, including whitebark pine (Hamann and 

Wang 2006).

• The British Columbia Ministry of Forests and Forest 

Genetics Council of British Columbia has drafted a gene 

conservation strategy for whitebark pine (Krakowski 

2001).

• The British Columbia Ministry of Forests has collected 

cones and seed for storage to conserve genetic diversity 

and to test for rust resistance to blister rust.

• Because of the mandate to minimize anthropogenic 

damage and restore damaged ecosystems, local 

restoration activities have occurred within some 

protected areas in British Columbia.

The British Columbia Forest Service divides the province into three administrative regions: Coast Forest Region, 

Northern Interior Forest Region and Southern Interior Forest 

Region (http://www.for.gov.bc.ca/mof/regdis.htm#rco).

Alberta

In Alberta, whitebark pine was recently approved for legal 

listing as Endangered because of an ongoing and projected 

decline in populations across the province. Although there 

are neighboring whitebark pine populations in Montana and 

British Columbia, blister rust and mountain pine beetle are 

present in both geographic regions, reducing the likelihood of 

seed dispersal (Alberta Sustainable Resource Development 

and Alberta Conservation Association 2007). Furthermore, 

there may be insufficient quality habitat for successful establishment of emigrant pines given the presence of blister 

rust and mountain pine beetles in Alberta, even if nutcrackers could disperse seeds from Montana or British Columbia. 

Therefore, rescue of Alberta whitebark pine populations 

from other jurisdictions is unlikely. The Alberta provincial 

government is working on a gene conservation strategy.
44 USDA Forest Service RMRS-GTR-279. 2012.
USDA Forest Service RMRS-GTR-279. 2012. 45

In this chapter, we describe how the range-wide whitebark 

pine restoration strategy (Figure 2.1) can be implemented 

across the six scales of analysis (Figure 2.2). Several elements are discussed at each scale. First, we present a 

description of the scale to provide spatial context for the following four topics. Next, the assessment factors that can be 

accomplished at that scale are discussed. Then, we suggest 

possible restoration actions to help guide managers to develop range-wide-to-local restoration plans. This is followed 

by a discussion of management concerns that may need to 

be addressed. Last, examples of restoration actions at the 

scale under discussion are presented. For the coarsest scales, 

a detailed restoration plan is provided instead of examples to 

guide local restoration action implementation. For example, 

at the scale of whitebark pine’s range, we have combined a 

number of spatial data layers to create a prioritization of possible regions for restoration.

Range-Wide Scale

This is the coarsest scale of analysis and is defined in this 

report as all lands that encompass the entire range of whitebark pine in the contiguous United States (lower 48 states) 

and western Canada (Figure 1.2). In this report, the range of 

whitebark pine can be spatially stratified into five broad regions (see next section) to correspond to other conservation 

and restoration efforts (Figure 4.1). These geographic regions include nearly all whitebark pine in the United States 

and Canada.

Assessments

Several core GIS layers are required for a comprehensive 

assessment of restoration potential and priority at this coarse 

scale. A key layer is a digital range map of the spatial distribution of whitebark pine. Keane (2000) developed a digital 

range map using an empirical approach where the elevational limits of whitebark pine were predicted using data from 

Pfister and others (1977). Other spatial distribution maps include digitized versions of the Little and Critchfield (1969) 

range map, the Arno and Hoff (1990) range map, and the 

Warwell and others (2007) empirical bio-envelope distributional map. Another important digital layer is a coarse-scale 

land ownership map provided by the U.S. Forest Service 

that shows Regions, National Forests, Wilderness Areas, and 

National Parks. Finer delineations of management emphasis 

areas would also be useful.

Perhaps the most important data layers for this assessment are digital maps representing the decline of whitebark 

pine across its range. Helmbrecht and Keane (in prep) have 

developed a GIS layer that maps the levels of rust infection 

in whitebark pine across the western United States. This 

map was created using gradient modeling where environmental factors such as temperature, precipitation, and 

topography were used to predict rust infection levels using 

statistical models based on data provided in the WLIS database (Lockman and others 2007). Kearns (2005) used a 

similar approach in predicting blister rust levels in Colorado 

that was later evaluated by Howell and others (2006). 

Kendall and Keane (2001) developed a map of whitebark 

pine mortality and rust infection, but the map detail may be 

too coarse for a comprehensive restoration plan. A map of 

current mountain pine beetle outbreaks and mortality is also 

important, but it may have to be created for the entire range 

of whitebark pine.

4. Restoration By Spatial Scale

Figure 4.1. Broad regions used in this report to stratify 

geographical areas within the range of whitebark pine in 

the United States and Canada.
46 USDA Forest Service RMRS-GTR-279. 2012.

Other important maps included in this assessment represent the current major issues associated with whitebark pine 

forests. A critical map used here is the current distribution of 

grizzly bear range across the range of whitebark pine. Other 

important maps might be species distributions of lynx and other endangered endemic plants and animals of whitebark pine 

communities. Human settlement maps, such as the wildlandurban interface (WUI) and county population level, would 

help identify those few whitebark pine lands that are adjacent 

to development. Last, transportation maps of road and trail 

densities could help identify those areas that have access for 

proactive restoration activities. Additional maps that could 

be used to plan restoration are based on bioclimatic models 

that attempt to show the changes in whitebark pine elevation 

and latitudinal distribution with climate change (Hamann and 

Wang 2006; McKenney and others 2007; Schrag and others 

2007; Warwell and others 2007). These predictions are informative but must be regarded as coarse-scale predictions 

because they do not incorporate many local environmental 

and physical variables (Keane and others 2008b).

Restoration Actions

One of the most important actions at this coarse scale is 

the creation of a range-wide genetic resistance program to 

promote the conservation of rust resistance in whitebark pine. 

This program would identify and mark possible rust-resistant, 

cone-producing trees in high blister rust areas (Mahalovich 

and Dickerson 2004), while seeking the greatest amount of 

genetic variation possible. Cone collections from these trees 

could provide an immediate seed source for operational reforestation, ex situ genetic conservation, and seedlings for blister 

rust resistance screening (for example, the Pacific Northwest 

Region ex situ gene conservation strategy described by Bower 

and Aubry [2009]). Pollen can be collected for genetic conservation and to advance blister rust resistance in seed and 

breeding orchards. Data from rust screenings can uniquely 

identify whitebark pine seed sources that provide high levels 

of blister rust resistance.

In 2001, Mahalovich and Dickerson (2004) created a 

multi-state restoration program (Idaho, Montana, Nevada, 

and Wyoming) designating permanent leave trees and selecting the healthiest, least infected trees in high blister rust- and 

mountain pine beetle-affected areas. Leave trees are elevated 

to elite-tree status based on their rust-resistant progeny in the 

rust screenings, and used as (1) a source of scion for root stock 

grafts in seed orchard creation, (2) a seed source for operational collections, and (3) seed trees for natural regeneration. 

Survivors of the blister rust screening are planted in clone 

banks for genetic conservation purposes to serve as donors for 

future seed orchard establishment and to facilitate selective 

breeding. Along with this program came recommendations 

about mixed seedling plantings following published seed 

transfer guidelines and suggestions for planting seedlings 

from other seed zones with warmer climates. However, genetics data for the U.S. northern Rockies region analyzed with 

geo-climatic variables do not support planting of whitebark 

pine seedlings from warmer climates because there is both 

the blister rust resistance and late winter cold hardiness issues 

due to the span of over 1600 m in elevation from northwest 

to southeast. This allows a bet-hedging strategy facilitating 

whitebark pine survival and genetic migration under current 

and near future climate.

Another important action is the prioritization of regions 

or subregions for coarse-scale planning, such as allocating 

national resources for finer-scale restoration efforts. In one example, prioritization could involve the distribution of funding 

to regional scale stratifications (National Forest and Regions). 

Another example could involve the implementation of the 

rust-resistance program for determining when and where to 

allocate valuable restoration funds. Prioritization might be 

based on the status and health of whitebark pine forests, the 

likelihood for favorable outcomes, or the decision to establish whitebark pine “core areas” from which seeds eventually 

could be dispersed to neighboring areas (Tomback and Achuff 

2010). It could also be based on numerous other concerns 

such as available management expertise, grizzly bear population distribution, available research results, extent of potential 

whitebark pine areas, and favorable land management policies (wilderness versus non-wilderness).

Other important restoration actions at this level include 

developing the knowledge, experience, and resources needed 

to implement effective restoration strategies. This involves 

an integrated basic and applied research program aimed at 

obtaining the knowledge and data that will be useful in the 

conservation of whitebark pine. Developing, collecting, and 

maintaining the comprehensive spatial data that provide 

context for restoration actions are also important tasks to 

proactively gain necessary information to evaluate risk and 

design restoration plans at multiple scales. Mapping the distribution of the species, threats to this species, spatial context 

(land ownership, wilderness, and roads, for example), forest 

structure and developmental stages (successional stage), and 

condition (level of mortality) at various scales is an important first step. Standard GIS spatial analysis techniques can 

be used on available digital maps describing ecology and 

management issues to provide the critical spatial information 

needed for many restoration efforts. Developing supporting 

technologies for whitebark pine management is also critical—

for example, finding new ways to harvest cones; improving 

nursery techniques to reduce seedling costs; exploring new 

ways to regenerate whitebark pine using seed planting techniques; and developing standardized methods for monitoring, 

inventorying, and describing whitebark pine health, populations, and seed production.

Education is also effective at this level. Education and 

training programs for agency personnel is critical for planning 

and implementing successful whitebark pine restoration programs. Educating the public on the plight of whitebark pine 

is also critical in that it might improve support for restoration 

projects. The Whitebark Pine Ecosystem Foundation (www.

whitebarkfound.org) is dedicated to restoring whitebark pine 

ecosystems throughout its range, and one of its missions is to 

educate people about the values and potential for restoration.
USDA Forest Service RMRS-GTR-279. 2012. 47

Management Concerns

A major concern is that some regions might be funded for 

restoration over others because of their higher prioritization. 

It will be difficult in the restoration prioritization process to 

decide funding allocation based on regional and range-wide 

parameters. Just because there are fewer whitebark pine trees 

in one region does not mean that region should get less funds 

for restoration—all whitebark pine forests are important for 

conservation. The design and development of prioritization 

analysis methods are critical for implementing range-wide 

restoration policies and actions. Another major concern is 

that maps will be included in range-wide assessments that 

may not match the scale of analysis. For example, a layer 

that depicts whitebark pine cover types may not be appropriate at the range-wide scale of analysis because cover types 

are quite variable within coarse resolutions and grain sizes.

A Range-Wide Prioritization for 

Whitebark Pine

The following is a proposed coarse-scale prioritization 

strategy to restore whitebark pine across its range in the 

United States. This strategy is not a final product but rather 

a baseline for conducting future prioritization efforts, and 

it should be improved as additional spatial data layers, new 

inventory and monitoring data, and new research become 

available. We realize that any prioritization is ultimately 

governed by the objective(s) of that prioritization, which can 

be as simple as determining where to allocate resources or 

as difficult as deciding which wilderness areas should be targeted for whitebark pine restoration.

Comprehensive, consistent, and accurate spatial data layers are desperately needed for successful prioritization plans. 

Unfortunately, few data layers were available to use for this 

prioritization effort. First, we found no data layers for all 

lands in Canada that represented whitebark pine. Second, 

most other data layers were inconsistent or too general 

across the entire range of whitebark pine, so Canada was not 

included in this analysis. Despite our best efforts, we were 

unable to locate or modify any coarse-scale data layers that 

were useful in the context of whitebark pine management. 

As a result, this prioritization has two parts. The first part is 

the description of limited prioritization effort using existing 

data layers, and the second part is a list of prioritization criteria that can be used for a coarse-scale effort once suitable 

data layers are available.

The three spatial data layers that we used to identify lands 

that are in the greatest need for restoration are:

•	 Whitebark pine range (Figure 4.2a). We used the 

Helmbrecht and Keane (in prep.) layer because it is 

consistent with the following blister rust infection layer.

•	 Rust infection map (Figure 4.2b). We used the Helmbrecht and Keane (in prep.) infection map to identify 

those regions that have the highest rust infections and 

used a 50 percent infection rate to identify low (less than 

50 percent) and high (greater than 50 percent) infection 

areas.

•	 Grizzly bear habitat (Figure 4.2c).

•	 Ownership (Figure 4.3). Only Federally administered 

lands were included in this layer along with various 

agency geographic boundaries.

Figure 4.2. Maps used in the prioritization of whitebark pine areas for restoration: (a) empirically derived range map from 

distributional data (whitebark pine shown in red) (Helmbrecht and Keane [in prep.]), (b) rust infection level for whitebark 

pine across its range outside of Canada by Helmbrecht and Keane [in prep.]), and (c) range of the grizzly bear (shown in 

red) in the western United States.
48 USDA Forest Service RMRS-GTR-279. 2012.

Figure 4.3. Federal 

ownership digital 

layer across the 

range of whitebark 

pine in the western 

United States 

and lands within 

the Regions of 

the USDA Forest 

Service.

Figure 4.4. Range-wide 

prioritization of whitebark 

pine restoration.
USDA Forest Service RMRS-GTR-279. 2012. 49

Based on these layers, we prioritized National Forest 

Regions (Figure 4.3) (not the regions in Figure 4.1) by 

overlapping these spatial layers and summing the area of 

overlap by the landscape stratifications (Figure 4.4). The 

total area in need of whitebark pine restoration is summarized in Table 4.1 by land ownership and National Forest 

Regions. This final layer forms the core prioritization areas 

for possible reference in planning coarse-scale restoration 

programs.

Many other data layers should be added to this analysis 

once they become available. Layers that describe whitebark pine range loss rates from climate change predictions 

(http://forest.moscowfsl.wsu.edu/climate/) could be used to 

target areas where whitebark pine is most at risk. We could 

also add layers that describe road and trail density to identify areas for proactive treatment using prescribed fire or 

mechanical cuttings (Keane and Parsons 2010b). Layers 

portraying whitebark pine mortality from disturbance would 

Table 4.1. Hectares of whitebark pine range by Forest Service Region and land ownership type in the western United States.

Land ownership Whitebark pine range

Blister rust 

infection 

(>50%)

Grizzly bear 

range

Restoration 

plan*

U.S. Forest Service Regions

Northern (Region 1) 2,757,580 1,274,020 62,831,600 844,372

Rocky Mountain (Region 2) 418,650 284 12,045,300 87

Intermountain (Region 4) 1,805,190 21,083 12,023,900 3,747

Pacific Northwest (Region 6) 668,967 153,958 4,283,170 8,085

Pacific Southwest (Region 5) 119,155 0 0 0

Land ownership

Forest Service 2,708,687 688,818 387,544 328,932

National Park Service 584,111 139,538 317,308 139,538

Private or State lands 166,241 35,816 17,400 20,616

Wilderness 2,178,084 537,229 461,192 329,938

Centennial Mountains Sheep 

Experimental Station 3,047 1,691 1,672 1,691

Bureau of Indian Affairs 71,391 38,608 29,884 33,476

Bureau of Land Management 55,922 6,707 5,284 2,121

Department of Defense 2,362 1,268 384 437

Fish and Wildlife Service 168 7 52 7

Total hectares 5,770,013 1,449,682 1,220,720 856,757

*This range-wide restoration plan includes only areas with >50% blister rust infection that are also within the range of grizzly 

bears.

also be valuable, such as a fire severity atlas (fire severity of 

recent fires) and mountain pine beetle damage maps.

This core prioritization can be augmented with any number of other layers to focus the prioritization for multiple 

objectives. Regions could be prioritized based on the extent 

of designated wilderness and areas that allow controlled 

wildfires. Also, care should be exercised when deciding 

priorities based on the extent of whitebark pine forest area 

within a region unless area is specifically part of the objective. Instead, it might be more appropriate to use percent 

of total area if the prioritization objective does not need to 

incorporate area itself in the decision process. We also urge 

caution when mixing scales in the GIS overlay process. In 

summary, it is impossible at this time to anticipate the ultimate objectives of Federal land management agencies for 

whitebark pine restoration planning. Therefore, we suggest 

that our core prioritization layer summarize conditions that 

are important for all planning efforts.
50 USDA Forest Service RMRS-GTR-279. 2012.

Regional Scale

This scale defines large regions that are important to 

stratify for restoration planning for whitebark pine across its 

range. In this report, we use U.S. Forest Service Regions and 

Canadian Provinces as our spatial delineation for simplicity and consistency, but we could easily have used Bailey’s 

(1995) sections, the regions in Figure 4.1, or major mountain 

ranges. Regions can be described by land divisions within 

the range of whitebark pine. These divisions might be along 

ecological boundaries, such as the seed transfer zones presented by Hoff and others (2001), hydrological subdivisions 

such as Level 4 code HUC (Hydrologic Unit Code) (USGS 

1987) watersheds, or mapping zones such as the ecological 

zones used by the EROS Data Center (Rollins and others 

2006).

Assessments

Essentially the same layers used for range-wide assessments can be used at this regional scale because the main 

action for restoration at this scale is again prioritization. At 

the regional scale, the emphasis for prioritization can be on 

other, more specific factors such as:

•	 Amount of funding available. How much money is 

available to perform restoration actions? Low funding 

might indicate that planning and analysis tasks could 

be performed in preparation for future implementation, 

while high funding levels might indicate that restoration 

treatments can be implemented and assessments can be 

designed to emphasize lands that can have proactive 

treatments.

•	 Available human resources. How many people are 

experienced in whitebark pine restoration planning and 

activities? Can some restoration efforts be contracted 

out? The depth of available expertise is an important 

factor when deciding if a region has the ability to 

conduct restoration activities. This is especially true if 

prescribed burning and silvicultural cuttings are being 

considered.

•	 Current management. Can current management 

plans hinder whitebark pine restoration plans? For 

example, wildland fire use can only be considered if 

areas within the region are covered by fire management 

plans. U.S. Forest Service policy of not planting trees 

in wilderness could also affect any proactive restoration 

plans. Management plans for Endangered or Threatened 

Species might also influence restoration actions in some 

areas.

Restoration Actions

The design of a gene conservation strategy through seed 

collections and a blister rust screening program for restoration efforts is perhaps the most important restoration activity 

that is efficiently accomplished at this scale. Development of 

a regional cone collection program using the seed zones described by Mahalovich and Hipkins (2011) would represent 

a significant step to ensure sufficient seeds are available for 

planting post-burn or post-treatment areas with viable whitebark pine seeds or seedlings that are putatively resistant to 

blister rust.

Another important activity is the regional development 

of a selective breeding program for whitebark pine, as was 

discussed at the range-wide scale. There is a general consensus among land managers that we should continue a genetic 

restoration program with an emphasis on selective breeding 

for white pine blister rust resistance. Identifying and collecting seeds from phenotypic rust-resistant individuals for this 

program is a high priority, and participation by all National 

Forests, Bureau of Land Management, and National Park 

Service and Canadian partners in the whitebark pine’s range 

is strongly encouraged. Stands with high infection levels are 

a high priority for cone collections from phenotypically resistant trees (Hoff and others 2001).

The Northern, Rocky Mountain, and 

Intermountain Regions Genetic Restoration 

Program for Whitebark Pine

An Inland West Genetics Shared Services Agreement 

established in 1995 provides the framework for a multiregion, multi-agency, trans-boundary partnership covering 

Idaho, Montana, Nevada, Wyoming, and Alberta, Canada 

(Mahalovich 2000; Mahalovich and Dickerson 2004). The 

Northern, Rocky Mountain, and Intermountain Regions; 

USDI National Park Service; USDI Bureau of Land 

Management; Parks Canada; and Alberta Tree Seed Centre 

are active participants. Program goals include:

1. complete operational cone collections for planting to 

improve critical wildlife habitat and restore properly 

functioning watersheds,

2. designate plus trees and collect cones for rust screening 

and genetic conservation,

3. evaluate patterns of genetic diversity in molecular 

markers and genetic variation in adaptive traits,

4. refine seed transfer guidelines,

5. establish production seed and breeding orchards of 

blister rust-resistant whitebark pine,

6. compile a comprehensive genetics profile for conserving 

highly diverse and rust-resistant populations across the 

landscape,

7. develop clone banks and a live-tree network across the 

landscape for gene conservation, and

8. install long-term genetic tests to monitor the durability of 

rust resistance.

Rust resistance testing of seedling progenies of candidate plus trees is performed at the U.S. Forest Service Coeur 

d’Alene Nursery, Coeur d’Alene, Idaho. Mahalovich and 
USDA Forest Service RMRS-GTR-279. 2012. 51

Dickerson (2004) provided the sampling design for seed 

collections to capture rust-resistant candidate trees and to 

capture desirable gene complexes by broadly sampling the 

physiographic and elevational breadth of the species. Each 

agency voluntarily participates in gene conservation cone 

collections for the National Center for Genetic Resources 

Preservation in Fort Collins, Colorado. Field activities are 

facilitated among partners within each seed zone (for example, GYA Subcommittee and the Northern Continental 

Divide working group) to optimize available resources.

The program began with cone collections in 1991 when 

provisional seed transfer and operational cone collection 

guidelines were delineated using known blister rust infection levels and physiography (Mahalovich and Hoff 2000). 

Genecology and molecular genetics studies ran concurrently 

with a rust screening and cold hardiness trial (1999 to 2005) 

(see “Genetics” section). Phase II was initiated in 2001, following the numerous wildfires in 2000. Approximately 1024 

plus tree selections among five seed zones comprised the 

testing population. Designating new plus trees is ongoing to 

replace those plus trees lost to mountain pine beetle and fire 

and to meet gene conservation objectives. Three rust screenings of over 95,000 seedlings in 2011 are under evaluation. 

At the completion of each screening, two performance tests 

are established in whitebark pine cover type.

Recently, each National Forest and two National Parks 

developed a 10-year comprehensive seed procurement plan 

summarizing: (1) number of pounds of blister rust-resistant 

seeds needed for operational planting, (2) number of seedlings needed for coordinating production needs at nurseries 

and for determining acreages for seed orchard establishment, 

and (3) number of planting acres for large-scale disturbance 

to have enough seeds on hand for climate change as the severity of mountain pine beetle epidemics and increases in 

uncontrolled wildfires are attributed to warming trends and 

drought conditions. Four production seed orchards are under 

development to meet planting needs 

in the northern Rockies.

A comprehensive genetics profile (Mahalovich and Hipkins 2011) 

is periodically updated as new plus 

trees are selected in the genetics program and evaluated in rust screening, 

genecology, and molecular studies. 

Areas with high genetic diversity, 

blister rust resistance, or rare alleles facilitate restoration efforts and 

facilitate identification of new candidate locations for the U.S. Forest 

Service Research Natural Areas program (Evenden and others 2001). A 

recent compilation of these genetic 

resources is incorporated in a GIS 

layer (Figure 4.5). There is sufficient 

genetic diversity, genetic variation, 

and absence of inbreeding to support 

the continuation of a rust resistance 

screening and genetic restoration 

program (Mahalovich and Hipkins 

2011).

Figure 4.5. A compilation of 

genetic resources in the 

northern Rocky Mountains.
52 USDA Forest Service RMRS-GTR-279. 2012.

Management Concerns

The consistent representation of whitebark pine status 

and trends across all lands within a region is one of the 

major concerns at this scale. Spatial data layers portraying 

vegetation, rust infection, and beetle-caused mortality are 

often inconsistent in detail and accuracy across an entire 

region. Another major concern is that management issues 

that are important to National Forests, National Parks, and 

Provincial Forests will not be represented by the suite of 

available data layers. For example, the current status of 

mountain pine beetle mortality might not be represented 

in National Forests where the outbreak is just starting. As 

with the range-wide scale, the design and development of 

prioritization analysis methods are critical for implementing 

region-wide restoration policies and actions, and prioritization variables have different weights across areas within the 

region. For example, National Forests with low abundance 

of whitebark pine might receive low priority, but active management of whitebark pine in these areas might be critical to 

avoid their extirpation.

The U.S. Forest Service Northern Region 

Restoration Strategy for Whitebark Pine

The Northern Region’s Integrated Restoration and 

Protection Strategy (IRPS) draws upon the basic premises 

of the national strategic goals and uses integrated objectives 

to prioritize and accomplish regional ecosystem restoration 

and protection of values at risk. The scale of consideration 

for the Strategy is the Northern Region of the U.S. Forest 

Service, which includes 12 National Forests located within 

the perimeter of northeastern Washington, northern Idaho, 

and Montana, and the National Grasslands in North Dakota 

and northwestern South Dakota. The Strategy is intended to 

be dynamic and will be continually amended as needed to 

address new information, changes in conditions, and changes in national priorities. The intent is to develop a common 

vision for addressing resource conditions across geographic 

areas independent of National Forest administrative boundaries. This Strategy is needed to promote integration among 

programs and budgets and to set priorities for investments in 

restoration and protection projects. It also sets the stage for 

addressing the relationships between wildfire and wildland 

fire use for the future.

The focus of the Northern Region’s IRPS is to:

• Restore and maintain high-value watersheds in a 

properly functioning condition;

• Restore and maintain wildlife habitats, including 

restoring resilient vegetation conditions where 

appropriate, to meet ecological and social goals; and

• Protect people, structures, and community infrastructure (roads, bridges, and power corridors) in and 

associated with the WUI.

The strategy uses the foci described above, including resiliency of vegetation, which contributes to the distribution 

and quantity of specific vegetation categories across the 

Northern Region, and characterizes the values that may be 

at risk in the event of uncharacteristic and geographically 

large fire events.

Some management tools that help achieve desired 

conditions for vegetation, specifically to promote ecosystem resiliency, diversity, and watershed health, include: 

(1) wildland fire use, (2) prescribed burning, (3) mechanical fuel treatments, (4) road restoration, and (5) elimination 

or reduction of invasive species. The mix of tools that are 

used for restoration and protection projects address specific 

conditions within the general land categories. For example, mechanical treatments may not be appropriate where 

backcountry and wilderness values are priorities. Likewise, 

wildland fire use may not be the most appropriate tool in 

the WUI. Some of the specific resources and values that are 

addressed by this strategy and that are influenced by natural 

processes and cultural treatments are:

• community infra-structure,

• old growth forest,

• threatened, endangered, and sensitive wildlife and plant 

species,

• wildlife habitat, including resilient vegetation 

conditions,

• watersheds and fish habitat,

• municipal watersheds, and

• recreation facilities.

Three focus areas for strategy implementation are: 

(1) identifying values that are directly threatened by potential 

large geographic scale fires; (2) restoring and maintaining 

watersheds and fish habitat; and (3) maintaining resilient 

vegetation conditions that restore wildlife habitat. The follosing are specific action items used to build a spatial map of 

priority areas that are regionally significant:

1. Protect people, structures, and community infra-structure 

(roads, bridges, and power corridors) that may be 

influenced by large geographic scale fire and large 

mountain pine beetle outbreaks.

2. Identify areas or watersheds that are fish and watershed 

restoration areas.

3. Promote opportunities to restore resilient vegetation that 

also function as key wildlife habitats.

4. Identify municipal watersheds.

5. Identify recreation areas that may be threatened by 

disturbance based on past investments and the level of 

people that use these areas.

The Strategy recognizes that resource conditions and values 

may vary at the Forest/Grassland or Ranger District scale. 

Areas outside the potential path of a “geographic fire” risk 

area or that are not spatially located on the map of priority areas that are regionally significant may still be a high 
USDA Forest Service RMRS-GTR-279. 2012. 53

priority for treatment at local scales; individual units can use 

this same approach to address those unique situations.

Whitebark pine restoration is addressed in Scenario 

2a under Theme 2 “Terrestrial Species: Unique Wildlife 

Habitats.” Whitebark pine was identified during the 1998 

Northern Region Overview as a rare landscape element because it is an important species and dominates a unique plant 

community. A number of spatial data layers are used as input 

in the prioritization process. Because the Northern Region 

IRPS Whitebark Pine Restoration Strategy is still under development, we present our interpretation of these layers in 

the context of this report. While our analysis is detailed and 

comprehensive, it is meant for illustration purposes. It does 

not replace IRPS, even though it will be quite similar to the 

finished product since we are using the same data layers.

The analysis has a core restoration plan that includes core 

data layers that describe ecological processes important in 

whitebark pine conservation. We used the Helmbrecht and 

Keane (in prep.) white pine blister rust data layer to determine areas that have greater than 50 percent infection 

(Figure 4.6a). In this layer, we also included points that 

correspond to trees found to be susceptible to blister rust 

based on field sampling. To describe damage from mountain 

pine beetle, we used data from the Aerial Detection Survey 

conducted by the Northern Region (Figure 4.6b). For prioritization purposes, we only included those areas that had 

more than three dead trees per acre due to mountain pine 

beetle. Spatial information for crown fire potential was 

based on data created with the large fire simulator FSIM for 

the Northern Region (Figure 4.6c). This data layer shows 

areas that are considered to have the potential for crown 

fire according to the following criteria: (1) flame length 

greater than 6 ft, (2) areas where the canopy cover is greater 

than 10 percent using the LANDFIRE cover layer (Rollins 

2009), and (3) areas where the Scott and Burgan (2005) Fire 

Behavior Fuel Model values are greater than or equal to 161.

The spatial overlay of these layers is shown in Figure 4.7 

by land ownership to form the core whitebark pine restoration plan, and the summary statistics are described in 

Table 4.2. In short, the majority of land that is high priority 

Figure 4.6. Core data layers used in 

the whitebark pine restoration plan 

for the U.S. Forest Service Northern 

Region: (a) areas in red where white 

pine blister rust has greater than 

50 percent infection, (b) areas in red 

where whitebark pine mortality from 

mountain pine beetle is greater than 

3 dead trees acre-1, and (c) areas in 

red where the probability of crown 

fire is high.

(a)

(c)

(b)
54 USDA Forest Service RMRS-GTR-279. 2012.

for restoration occurs in protected areas (wilderness) of the 

Crown of the Continent ecosystem (Glacier National Park 

and the Bob Marshall Wilderness Complex). We then adjusted this core restoration plan by excluding all lands that 

have burned since 1988, based on the Northern Region 

fire atlas compiled from the project Monitoring Trends in 

Burn Severity (Figure 4.8). This adjustment, as shown in 

Figure 4.9 and Table 4.2, still has most of the critical lands 

that need restoration included within Montana wilderness. 

It is important to note that most of the lands in this restoration plan can be treated using wildland fire (wildland fire 

use or controlled wildfires) (Table 4.3) under the Northern 

Region’s Appropriate Management Response area designations (Figure 4.10).

The Northern Region’s IRPS used these findings along 

with the Ecosystem Management Decision Support (EMDS) 

Tool to determine priority areas for treatment based on resource value, indicators of risk, levels of departure, and 

potential response to various treatments on 6th HUC (USGS 

1987) watersheds. In EMDS, as in most prioritization efforts, 

there are two tasks involved in determining final prioritization scores: spatial data analysis (EMDS logic engine) and 

data layer weighting. The spatial data analysis was previously described, while the weighting of the layers used in the 

analysis followed a more subjective approach. All scenarios, 

including the whitebark pine scenario, are scored (weighted) 

using three components—Value, Risk, and Feasibility—

that total to a score of 100 based on the weights given each 

of the three values. These components and the associated 

treatment options will vary based on several criteria, including: (1) location (roaded, non-roaded, and wilderness), and 

(2) type of vulnerability (shade-tolerant tree dominance due 

Figure 4.7. The core 

whitebark pine (WBP) 

restoration plan by 

land ownership. 

Conservation areas are 

shown in red.

to fire exclusion, blister rust, mountain pine beetle, and probability of crown fire). The weighting of each of these data 

layers was assigned based on the importance to managers 

of each issue. The Value component was assigned a value of 

40, all of which is assigned to the percent of whitebark pine 

occurrence in a 6th code HUC watershed. The Risk component was given a score of 30, with 20 assigned to crown fire 

burn probability, 5 assigned to blister rust damage, and 5 

assigned to insect occurrence (and mortality) from 2002 to 

2009. The Feasibility component had a value of 30, with 25 

assigned to non-wilderness and non-roadless areas, and 5 assigned to Monitoring Trends in Burn Severity (MTBS) data 

layers with moderate- to high-severity fire (www.mtbs.gov) 

to identify where recent site preparation was provided by 

the fire, thus enabling planting of whitebark pine seedlings, 

if necessary. The EMDS model was run for each scenario 

to determine which 6th code HUC (USGS 1987) watersheds 

received the highest score for the greatest number of scenarios. These watersheds will likely be given priority for 

various treatments. For example, certain 6th code HUC watersheds may have a number of resource values at risk that 

can be treated to meet the restoration objectives. These watersheds will therefore rank higher in priority for treatment 

compared to a watershed with a single value identified, or 

if less risk is identified. The opportunity scores for whitebark pine are shown in Figure 4.11. The red watersheds are 

the highest opportunity areas for whitebark restoration since 

they have the highest values at risk and the greatest potential for restoration. The Northern Region plans to revisit 

the Value, Risk, and Feasibility weights through an adaptive management process to test the assumptions, validate 

the prioritization process, and respond to changes on the 
USDA Forest Service RMRS-GTR-279. 2012. 55

landscape (for example, large fires and beetle killed trees). 

A 2050 version of the IRPS is being developed as part of the 

Regional Climate Change vulnerability assessment to project increases in vulnerability of the key elements identified 

in 2011. In this way, IRPS is a process based framework that 

can be periodically refined and modified.

The Pacific Northwest Region Restoration 

Strategy for Whitebark Pine

A comprehensive, regional plan for restoring whitebark pine was written for the U.S. Forest Service Pacific 

Northwest Region (PNW) (Aubry and others 2008a; Aubry 

and Shoal 2008). Like the range-wide strategy, the PNW 

Strategy also included several scales of analysis from the 

Table 4.2. Hectares of whitebark pine range in zones of threat by land ownership type in USDA Forest Service Northern Region.

Land ownership

Blister rust infection

(>50%)

Mountain pine beetle 

(≥3 dead trees ac-1) High crown fire potential Grizzly bear range Core plan Adjusted plan Grizzly bear adjusted plan

Forest Service 643,547 103,657 241,751 229,148 127,189 123,033 60,711National Park Service 139,450 8,274 75,867 308,764 9,441 9,346 9,346Private or State lands 34,124 2,515 7,808 12,576 4,505 4,483 3,040Wilderness 411,921 10,272 173,837 260,832 70,487 65,034 55,659Centennial Mountains—Sheep Experimental Station 1,545 262 350 1,600 233 233 233

Bureau of Indian Affairs 35,692 1,349 5,008 18,372 4,520 4,505 4,126Bureau of Land Management 5,220 1,400 2,333 1,304 729 729 211

Department of Defense 248 0 284 148 102 102 102

Fish and Wildlife Service 7 0 22 52 7 7 7

Bureau of ReclamationTotal hectares 1,271,755 127,728 507,260 832,796 217,213 207,473 133,436

Figure 4.8. Data layers (shown in red) used to adjust the core 

restoration plan (a) to address wildland fire issues using 

a spatial data layer showing areas that have burned in 

wildfires since 1988 and (b) to identify grizzly bear range.

(a)

(b)
56 USDA Forest Service RMRS-GTR-279. 2012.

regional level down to the landscape and stand levels. It 

is also supported by a number of ancillary documents that 

improve the efficacy of the strategy (Aubry and others 

2008b; Lorenz and others 2008). The overriding goal of this 

Strategy is to restore and conserve a network of viable populations of whitebark pine and associated species across 

the Pacific Northwest. There are five objectives listed to 

complete this goal:

1. Restore degraded habitat.

2. Protect genetic resources through gene conservation.

3. Increase blister rust resistance in whitebark pine 

populations.

4. Evaluate the health and status of whitebark pine stands.

5. Increase our understanding of the threats to whitebark 

pine and develop practical and effective restoration 

techniques.

Aubry and others (2008a) used an ecoregion approach 

based on a framework for ecoregional planning (Dinerstein 

and others 2000; Groves 2003). The steps included: (1) conduct ecoregional assessment, (2) identify threats, (3) select 

sites for restoration and conservation, (4) create a biodiversity vision, (5) set long- and short-term goals, and (6) 

prioritize actions. The end result was a site-based conservation and restoration blueprint.

Forest personnel used their professional judgment to assign proposed actions to management units by considering 

fire history, mountain pine beetle activity, blister rust severity, size of the area, stand age, competition from other conifer 

species, and reproductive capability of whitebark pine. The 

framework also considered the logistics of traveling to an 

area and the existence of any special management designations, such as designated wilderness or research natural 

areas, and potential benefit versus cost of restoration. The 

entire region was divided into 30 conservation areas, and 

each conservation area was then stratified by management 

Figure 4.9. The adjusted 

restoration plan that 

excludes all lands burned 

since 1988. Restoration 

areas are shown in red.

Table 4.3. Hectares of whitebark pine restoration plans by Appropriate Management Response (AMR) categories 

in USDA Forest Service Northern Region.

AMR

Restoration plan

Core Adjusted Grizzly bear

Resource Benefit with Plan 122,129 115,707 70,640

Resource Benefit 51,657 49,477 32,601

Protection 9,973 9,739 4,724

Appropriate Suppression 6,641 6,116 2,129

Not Coded 26,215 25,836 22,767

Total hectares 216,615 206,876 132,860
USDA Forest Service RMRS-GTR-279. 2012. 57

Figure 4.10. Areas 

describing Appropriate 

Management Response 

(AMR) for the Northern 

Region.

units with one or more of the following proposed actions 

assigned to each management unit:

1. Safeguard habitat. Conserve and safeguard from fire 

(both wild and prescribed).

2. Collect cones. Collect cones from mature whitebark pine 

stands with high potential for cone production.

3. Restore. Plant seed or seedlings, thin for conifer release, 

and/or prune. Included in this category are units that 

have burned or have high mortality due to mountain pine 

beetle infestation.

4. Survey condition. Survey to determine if whitebark pine 

is present, to record the general stand condition, and to 

determine what actions, if any, are needed.

5. Survey seed trees. Survey to determine if cone-bearing 

trees are present.

6. No action. Decide if management units have poor 

access, marginal habitat, or no need for planting or 

thinning.

A map showing conservation areas, management units, seed 

zones, and whitebark pine habitat is shown in Figure 4.11. 

Whitebark pine distribution and status varied greatly within 

the conservation areas and the nested management units. 

However, planting was needed in some part of every conservation area except for the Olympic Peninsula. Top priority 

for planting was given to management units located in grizzly bear habitat.

The PNW Restoration Strategy (Figure 4.12) also includes a genetics program with the following goals: gain an 
58 USDA Forest Service RMRS-GTR-279. 2012.

Figure 4.11. Opportunity scores for all 6th code HUC watersheds (USGS 1987) in the Northern Region IRPS 

prioritization for whitebark pine restoration with high scores indicating high opportunity for whitebark pine 

restoration activities. The code “s2a Opp Score” indicates the IRPS scenario 2a opportunity score.

Figure 4.12. Map depicting the whitebark 

pine restoration strategy for the Pacific 

Northwest Region for the states of (a) 

Washington, and (b) Oregon (Aubry 

and others 2008a).

(a)

(b)
USDA Forest Service RMRS-GTR-279. 2012. 59

understanding of the patterns of genetic diversity and adaptation in whitebark pine, use this knowledge to protect the 

whitebark pine genetic resource (gene conservation), and 

provide rust-resistant seeds for restoration. Rust resistance 

testing of seedling progenies to confirm resistance of candidate parent trees is conducted at the Forest Service Dorena 

Genetic Resource Center (DGRC). The regional ex situ gene 

conservation plan (Bower and Aubry 2009) outlines a sampling design for seed collection among populations across 

the region and long-term storage at both the DGRC and at the 

National Center for Genetic Resources Preservation under a 

memorandum of understanding with the USDA Agricultural 

Research Service in Fort Collins, Colorado.

A proactive approach is critical to prevent the permanent 

loss of whitebark pine habitat throughout much of whitebark 

pine distributional range in the Pacific Northwest. Aubry and 

others’ (2008b) Strategy includes a five-year plan for 2009 to 

2013 that targets the following activities:

• Collect seeds to meet gene conservation, rust resistance 

screening, and planting objectives.

• Assess the condition and determine restoration needs for 

all priority management units.

• Develop and implement a plan to plant seedlings in 

priority management units.

• Continue the ongoing rust screening program with 

emphasis on seed zones in grizzly bear recovery areas.

• Develop and implement a plan to treat mountain pine 

beetle in high risk units.

• Develop an approach for planting in designated 

wilderness areas that will allow the use of resistant plant 

material while maintaining wilderness character.

• Develop an approach to mitigate the predicted impacts 

of climate change.

• Develop monitoring plan(s) to track accomplishments, 

measure success of actions, provide information and 

feedback to improve procedures and outcomes of 

projects, and disseminate information.

• Work collaboratively to meet information needs.

A companion “Land Managers Guide” is available to 

plan and design local treatments (Shoal and others 2008). 

This PNW Strategy is easily the most comprehensive and 

detailed plan for a large region and provides the critical information to step concepts and knowledge presented in this 

report down to a finer scale. It serves as an excellent template for the development of strategies for other regions.

The Greater Yellowstone Area 

Whitebark Pine Restoration Strategy

As a foundation and keystone species of high-elevation 

ecosystems in the GYA, whitebark pine defines ecosystem 

structure, function, and process by providing snow capture, 

snow retention, carbon storage, biodiversity, and a food 

source for wildlife. Overstory mortality from combined 

blister rust, beetle, and climate change is unprecedented in 

many areas of the GYA, resulting in the need for an approach 

to whitebark management that links Federal administrative 

units throughout the GYA. To protect healthy whitebark pine 

and restore whitebark pine in areas with extensive overstory 

mortality, appropriate management actions must be coordinated, consistent, efficient, and science-based. In response 

to the current situation in whitebark ecosystems, the Greater 

Yellowstone Coordinating Committee’s Whitebark Pine 

Subcommittee, which has worked successfully across boundaries since its inception in 2000, developed this Whitebark 

Pine Strategy to promote the persistence of whitebark pine 

over time and space in the GYA by: (1) documenting the 

current condition of whitebark pine in the GYA; (2) establishing criteria to prioritize areas for management action; 

(3) identifying techniques and guidelines to protect and restore whitebark pine; and (4) facilitating communication and 

distribution of this information. This Strategy is intended to 

enable land management units to maximize the use of their 

limited resources to maintain whitebark pine as an important 

ecosystem component in the GYA.

The GYA Whitebark Pine Strategy is a living document 

that will be regularly updated to reflect changes in ecosystem conditions, advances in the understanding of whitebark 

pine ecosystems and management techniques, and improvements in the technology available to characterize and map 

whitebark pine. In addition, reviews by other resource staff 

such as fire managers, wildlife biologists, interpreters, and 

recreation specialists will provide the basis for integration of 

this strategy within individual management units as well as 

across the GYA. The Strategy contains four sections:

•	 Section 1. Introduction, Purpose and Need, and 

Strategic Objectives. Details the strategic objectives 

developed for assessing and conserving whitebark pine 

ecosystem condition in the GYA and describes the 

Whitebark Pine Subcommittee and its work to date.

•	 Section 2. Methods. Describes the assessment and 

prioritization of whitebark stands in the GYA by the 

Whitebark Pine Subcommittee.

•	 Section 3. Site Selection, Management Strategies, and 

Action Plan. Describes how whitebark stands within 

the GYA will be selected for management actions and 

addresses considerations for resistance, resiliency, and 

adaptive management relative to climate change. A 

three-year action plan based on current restoration and 

protection efforts and priorities is also presented.

•	 Section 4. Tools for Protection and Restoration of 

Whitebark Pine Stands. Describes potential tools and 

techniques for protecting and/or restoring whitebark 

pine stands (Table 4.4).

Forest Scale

The forest scale refers to any large consolidated area with 

multiple land management units that could include National 
60 USDA Forest Service RMRS-GTR-279. 2012.

Forests and National Parks. Once an assessment is completed at the forest scale, a landscape scale assessment (see the 

Landscape Scale section) and stand level assessment (see the 

Stand Scale section) are likely required to further refine the 

assessment of whitebark pine restoration needs.

Assessments

Assessments performed at this level can incorporate more 

detailed information than the range-wide and regional scales 

because wall-to-wall consistent data layers are more readily 

available. The following are some of the layers that are often 

available at this scale and the questions they can help address:

•	 Vegetation cover types and age classes. Where are the 

whitebark pine forests? How much of them are in late 

successional status? How much age class diversity is 

there within the area? Where should monitoring plots be 

located?

•	 Habitat types (potential vegetation). Where can 

whitebark pine grow, and where is it most likely to 

succeed to other conifers or be the dominant species?

•	 Insect and disease aerial detection surveys. Where has 

whitebark pine been killed by mountain pine beetle or 

other agents?

•	 Blister rust infection levels. Where has cone production 

been lost, and where are the best places to look for 

phenotypically rust-resistant trees to (1) collect seeds 

for planting, or (2) include in the genetic rust resistance 

breeding program?

•	 Threatened and endangered species habitat. Where 

could grizzly bears potentially use whitebark pine seeds 

collected from cones in squirrel middens? Can the 

process of prioritizing areas for restoration also help 

design projects in grizzly habitat that mitigate potential 

human-bear conflicts?

•	 Roads and trails: Where are potential treatment areas 

that are easily accessible?

Restoration Actions

An important restoration action implemented at this 

level is the collection of seeds from apparent rust-resistant 

whitebark pine trees, particularly from areas with high rust 

infection levels. Since whitebark pine is a species that can be 

planted across large regions, seed collection for whitebark 

pine is best employed at the forest scale. Mahalovich and 

Dickerson (2004) implemented an extensive whitebark pine 

tree improvement program for the Intermountain Region 

and summarized criteria for selecting plus trees for collecting cones (Appendix A). Trees that are considered desirable 

for harvesting seeds because of their observed rust resistance 

and robust qualities are called “plus” trees. Aeciospore collections for rust screening and pollen collections for seed 

orchard applications and breeding are also facilitated at the 

forest level.

Other genetics activities include establishing seed orchards and long-term genetic tests within their respective 

seed zones. Presently, there are four seed orchards at various stages of development servicing the Bitterroots-Idaho 

Plateau (Clearwater National Forest), Central Montana 

(Lewis and Clark National Forest), Greater YellowstoneGrand Teton (Gallatin National Forest), and Inland 

Northwest (Lolo National Forest) seed zones. Seed orchards 

are genetically designed for broad adaptability with a minimum effective population size of 30. A further design goal 

is to separate ramets (multiple copies) of the same genotype 

by 24 m to minimize inbreeding through cross-pollination. 

Where seed zones cover a wide range in elevations, orchards 

are stratified by elevation band for cold hardiness considerations (for example, the Little Bear Seed Orchard on the 

Gallatin National Forest). Seedlings from the 110-seed 

source study (Mahalovich 2012; Mahalovich and others 

2006), at the completion of the rust screening and cold hardiness trial, were planted on the Idaho Panhandle National 

Forests. Additionally, replicated, long-term performance 

tests are scheduled to be planted at the completion of each 

rust screening.

Table 4.4. The Greater Yellowstone Area whitebark pine restoration strategy simplified tools and techniques for restoration.

Protection Restoration

•	 Apply verbenone and carbaryl to prevent 

 mortality due to mountain pine beetle.

•	 Prune to remove blister rust infection and/or 

improve fire resistance.

•	 Prevent loss of high-value whitebark pine 

trees from fire.

•	 Natural regeneration

•	 Whitebark pine seed orchard

•	 Participation in whitebark pine genetic 

 conservation program 

•	 Collect whitebark pine seeds and cones.

•	 Plant whitebark pine seedlings and seeds.

•	 Development of guidelines and limitations for 

fire in whitebark pine stands

•	 Creation of nutcracker openings

•	 Thinning

•	 Natural regeneration
USDA Forest Service RMRS-GTR-279. 2012. 61

4. Prioritize the need for restoration at the stand scale by 

using the stand scale guidelines to determine a relative 

rating for each of the stands that have whitebark pine.

Prioritization can then be done at each of the three scales. 

In addition, priority ratings from all three scales for a stand 

(broad, mid, and stand) can be added to determine a total 

restoration priority rating for the stand. These scores can be 

compared to all other stands within the National Forest to 

determine which stands are the highest priorities for treatment considering multi-level priorities. For demonstration 

purposes, this process is illustrated using one principal watershed within the forest (broad-scale, Figure 4.13), all of the 

subwatersheds within that principal watershed (mid scale), 

and all of the stands within one subwatershed. The mid-scale 

analysis is discussed in detail in the Landscape Scale section and the stand analysis is discussed in detail in the Stand 

Scale section.

Step 1: Establish Whitebark Pine Vegetation Layer 

for the National Forest

A vegetation layer was created using the best information 

available for whitebark pine current and historic presence. 

Several different layers were joined to make the whitebark 

pine vegetation layer (WBP layer):

• Whitebark pine designations from the Grizzly Bear 

Cumulative Effects Model Map (CEM) (Weaver and 

others 1986).

• Stand examination data documenting the presence of 

whitebark pine.

• Whitebark plus tree location data.

• The 1966 Timber Inventory, whitebark pine component.

• Whitebark pine presence/absence map assembled by the 

USGS using satellite imagery.

• Local knowledge of employees and researchers familiar 

with the area.

• The 2130-m elevational band. Whitebark pine presence 

in this area is incidental at elevations below 2130 m, so 

everything below 2130 m was excluded. A validation assessment revealed that the layer tended to overestimate 

the amount of area with whitebark, but overall, it accurately predicted areas that are currently known to have 

whitebark pine. This was the best available information 

for the Caribou-Targhee National Forest at the time.

Step 2: Develop Forest-Scale Principal Watershed 

Process

Since whitebark pine is declining throughout its range, it 

was assumed that the greater the reduction from historical 

extent, the greater the loss of ecological function and the 

more urgent the need for restoration. The following losses 

were evaluated:

•	 Loss to mountain pine beetle. Aerial detection survey 

flights since 2000 were used to determine the number 

of acres lost (>10 trees per acre killed by mountain pine 

Another restoration action best conducted at this level 

is the inventory and monitoring of whitebark pine health 

and status. While some inventory and monitoring efforts 

are usually conducted at finer scales, the most effective are 

those that are coordinated at the broad or coarser scales. 

Many inventory and monitoring techniques are available for 

implementing programs that assess whitebark pine status. 

The most appropriate may be the inventory and monitoring 

methods on the Whitebark Pine Ecosystem Foundation web 

site (www.whitebarkfound.org) (Tomback and others 2005). 

These methods were developed specifically for whitebark 

pine and limber pine to be implemented at a broad-scale. 

Other methods that could be used are those in FIREMON 

(Fire Monitoring and inventory system) (Lutes and others 

2006) and FFI (Lutes and others 2009), which are available 

at the FRAMES (Fire Research and Management Exchange 

System) web site (www.frames.gov). FIREMON and FFI 

contain detailed methods for measuring trees and rust conditions and a discussion on how to design a sampling strategy. 

Other inventory techniques include those in FSVEG and the 

Fire Monitoring Handbook (USDI 2001). Shoal and Aubry 

(2006) also presented a set of core data attributes essential 

for whitebark pine surveys.

Management Concerns

The major concern at this level is that restoration resources may not be strategically or efficiently used across broad 

forest scale units, such as National Forests. Another potential concern is that there may not be enough personnel with 

sufficient time and experience to implement well-conceived 

whitebark pine restoration projects. Experienced personnel must be available to complete National Environmental 

Policy Act documents, pursue funding, and plan and implement treatments.

Example: Implementation of the Greater 

Yellowstone Restoration Decision Guidelines 

for the Caribou-Targhee National Forest

The process described in “Greater Yellowstone Area 

Decision Guidelines for Whitebark Pine Restoration” 

(Jenkins 2005) was used to prioritize whitebark pine restoration treatments on the Caribou-Targhee National Forest. 

General steps for implementing the guidelines were:

1. Establish a whitebark pine spatial data layer that displays 

where whitebark pine is located across the area of 

interest (Caribou-Targhee National Forest).

2. Prioritize the need for restoration at the broad-scale 

(Caribou-Targhee National Forest) by using the 

guidelines to determine a relative rating for each 

principal watershed that has whitebark pine.

3. Prioritize the need for restoration for each principal 

watershed by using the guidelines to determine a relative 

rating for each of its subwatersheds that have whitebark 

pine.
62 USDA Forest Service RMRS-GTR-279. 2012.

beetle is considered area lost). Mountain pine beetle 

typically kills the larger trees, which also tend to be 

the cone-bearing trees. Areas with high or increasing 

mountain pine beetle mortality were assigned a high 

priority for restoration.

•	 Loss from stand replacing fire. A fire history 

layer was intersected with the whitebark pine layer 

to identify whitebark lost from fire. The majority 

of the stand-replacing fire in the whitebark pine 

habitat occurred in 1988. Monitoring of the 1988 fire 

areas shows that whitebark pine is not adequately 

regenerating. Burned acres that have been planted with 

whitebark pine seedlings were excluded.

Since mature whitebark pine are more likely to be attacked by mountain pine beetles than young trees, it was 

assumed that maintaining a diversity of size classes would 

ensure that some stands are less likely to be killed by 

beetles. It also ensures that stands senescing out of cone 

production are being replaced. Small size classes are often 

limited in extent because fire exclusion has reduced the opportunities for whitebark pine to regenerate. The diversity 

of age classes needed was determined from the estimated 

fire return interval in the area for whitebark pine (200 to 325 

years) and whitebark pine’s prime cone production period 

(100 to 300 years). Areas with less than 25 percent in small 

size classes (seedling through pole less than 100 years old) 

were determined to have a high priority for restoration and 

areas with between 25 to 35 percent of the stands in small 

size classes were determined to have a moderate priority.

The Targhee National Forest vegetation layer and the grizzly bear classifications were combined and then overlaid 

with the whitebark pine cover layer to identify young stand 

age classes.

In general, within areas where blister rust levels are high, 

trees with low rust resistance have either died or their conebearing branches have been killed. Rust-infected trees with 

more than 20 to 30 percent of the crown killed can no longer produce good cone crops (Keane and Arno 2001). Open 

conditions suitable for regeneration are important in areas 

that have moderate levels (25 to 75 percent) of infection 

so that trees with rust resistance will have the opportunity 

to regenerate. If restoration treatments are postponed until 

few cone-producing whitebark pine remain, then virtually all of the seeds produced by the resistant trees will be 

consumed. Areas with high infection levels (greater than 

75 percent) were assigned the highest restoration priority.

Figure 4.13. Broad-scale forest areas used by the Caribou-Targhee National Forests to implement the Greater Yellowstone Area 

whitebark pine restoration strategy. (a) all lands in the assessment area (forest) and (b) stands within one 6th code HUC 

watershed.
USDA Forest Service RMRS-GTR-279. 2012. 63

In stands where whitebark is seral, successional progression causes whitebark pine to be replaced by more 

shade-tolerant tree species (primarily subalpine fir and 

Engelmann spruce). It was assumed that the greater the 

representation of the shade-tolerant species, the greater the 

decline of less shade-tolerant species such as whitebark 

pine. Because lodgepole pine is a shade-intolerant seral 

species, it will not replace whitebark pine at the rate of 

subalpine fir or Engelmann spruce. Stands succeeding to 

spruce and fir have a higher priority than stands succeeding to lodgepole pine. Climax whitebark pine stands have 

a low priority because they are not successionally replaced 

by other tree species.

Local extinctions may occur if stands of whitebark pine 

decline and seed sources are not close enough to provide 

adequate regeneration. Usually, 10 km was used as the 

maximum distance to expect nutcrackers to re-establish a 

whitebark stand, but that is a conservative estimate of nutcracker caching distance. All stands or polygons that were 

greater than 10 km from a whitebark pine seed source were 

assigned a high priority.

Whitebark pine seeds are an important source of energy 

for the grizzly bear (Felicetti and others 2003; Mattson 

and Reinhart 1994; Robbins and others 2006). In Bear 

Management Units (BMUs) with >13 percent of the area 

supporting mature whitebark pine, the relationship between 

availability of squirrel middens and use of middens is strong 

(Mattson 2000). Areas in BMUs that have the capability to 

support greater than 13 percent cone-bearing whitebark, 

but do not currently do so, have the highest priority for restoration. Results of the forest- (broad) scale prioritization 

process along with the mid-scale and stand-scale prioritization are shown in Table 4.5 and Figure 4.13b.

Landscape Scale

The landscape scale refers to local areas that are 

geographically defined by the spatial dynamics of the biophysical processes, such as disturbance and vegetation 

development, that shape them. These landscapes can be 

variable in size, but Karau and Keane (2007) found that 

typical western U.S. landscapes could be anywhere from 

50 to 200 km2 (10,000 to 50,000 acres) to encompass the 

full range of spatial dynamics in disturbances, hydrology, 

and biophysical setting, or a little bigger than the size of 

a 6th code HUC watersheds (USGS 1987) or a landform 

(Holdorf and Donahue 1990). Generally, landscape assessments would be implemented on sub-areas within 

the broad-scale assessment and should be no smaller than 

about 5000 acres, or 7th code HUC watersheds (USGS 

1987). A landscape is usually composed of and described 

by stands that are small areas of homogeneous vegetation 

Table 4.5. Broad-scale analysis for the Caribou-Targhee National Forests for restoring whitebark pine (WBP).

Consideration item Weight

Principle watershed 

#8 rating

Principle watershed #8 score

1. Change from historical acres 10 0 0

2. Age class distribution 10 1 10

3. Successional potential and status 5 2 10

4. Areas far from WBP seed source 5 1 5

5. Grizzly bear use 20 1 10

6. Level of blister rust 10 1 10

7. Level/trend of mountain pine beetle 20 1 20

Scorea (weight x rating)b 65

a

The score is calculated by multiplying the weight for that consideration item by the rating given to that item. The 

purpose of weighting is to incorporate the relative importance of the consideration item. Land managers completing 

the analysis assign the weights and can adjust them to reflect local management direction. The consideration item 

ratings are defined as follows:

b

Ratings are as follows:

Item 1. Small decrease or increase in acres = 0, moderate decrease = 1, large decrease in acres = 2

Item 2. Well distributed age classes = 0, Mod = 1, high percentage in older age classes = 2

Item 3. High percent landscape in whitebark pine climax = 0, Seral: High percent of whitebark = 0, high percent of 

landscape in lodgepole pine = 1, high percent of subalpine fir = 2

Item 4. Acres well distributed = 0, high mortality areas far from other seed sources = 1

Item 5. Grizzly bear use low = 0; use high and cannot support >13 percent whitebark pine = 1; grizzly bear use 

high and is supporting >13 percent of area with cone-bearing whitebark = 2, or same but is not supporting >13 

percent = 3

Item 6. Rust infections low = 0, rust infections moderate = 1, rust infections high = 2

Item 7. Mountain pine beetle levels low and stable = 0, beetle levels high or increasing = 1 
64 USDA Forest Service RMRS-GTR-279. 2012.

and site conditions (Turner and others 2001). Landscape 

composition is described by the plant species that dominate 

the stands that comprise the landscape, while landscape 

structure is the spatial pattern of stand types, such as patch 

density, contagion, and patch shape.

Assessments

Assessments performed at this scale would entirely 

depend on the availability, quality, and extent of appropriate GIS layers to describe the variables being assessed. 

Assessments will always differ across landscape for several reasons:

• Unique biophysical setting dictates the abundance and 

distribution of whitebark pine stands.

• Fire and other disturbance regimes will be dramatically 

different across landscapes comprising a broad area 

due to landform, topography, and orientation.

• Blister rust and mountain pine beetle impacts are 

highly heterogeneous across landscapes.

• Management issues will differ across landscapes and 

agencies depending on existing management plans and 

ownership.

Therefore, a one-size-fits-all approach to landscape assessments for whitebark pine restoration is often ineffective 

and inappropriate for most assessments, analyses, and 

applications.

Historical Range and Variation (HRV) 

Assessments

The concept of HRV is especially useful at the landscape scale (Morgan and others 1994a). In an operational 

context, the historical range and variation of landscape 

characteristics, mainly composition (species cover types) 

and structure (spatial pattern), can be used as a reference 

to compare with current conditions to calculate a measure 

of departure. This departure can then be used to prioritize 

landscapes for restoration (Keane and others 2007b). The 

assumption behind HRV is that the spatial arrangement, 

composition, and structure of vegetation communities on 

a landscape reflects the cumulative and interactive effects 

of past disturbance regimes, biophysical environments, and 

successional processes over long time periods. Historical 

fluctuations in landscape characteristics, such as species 

composition and structure, can provide an important reference for evaluating the current condition of the same 

landscape; a quantification of these fluctuations can be 

used to guide the design and implementation of restoration 

treatments (Keane and others 2009). Current landscape 

conditions can be compared with a set of historical landscape conditions to detect ecologically significant change, 

such as that incurred by fire exclusion and blister rust. This 

information can be used to plan and prioritize treatment 

areas where stands that have significantly departed from 

historical conditions may warrant treatment first.

In this report, we define HRV as the quantification of 

temporal fluctuations in ecological processes and characteristics prior to European settlement (prior to 1900) and 

before the introduction of blister rust. HRV is often highly 

scale-dependent and somewhat flawed conceptually due to 

climate change, human land use, and geologic processes. 

The variability of historical whitebark pine cover across a 

landscape, for example, depends on the range of years used 

to compute the HRV landscape cover statistics; fluctuations 

over a 1000-year period taken 10,000 years ago at the end 

of the last ice age would be dramatically different from a 

recent 1000-year time slice.

HRV has limitations in a spatial context. The HRV of a 

stand is meaningless unless it is described in the context of 

a landscape; for example, a subalpine fir stand might not 

be outside of HRV if the rest of the landscape is composed 

of whitebark pine. To use HRV in an operational context, 

it must be assumed that the record of historical conditions 

more or less reflects the range of possible conditions for 

future landscapes—an assumption that we now know to be 

overly simplistic because of documented climate change, 

exotic introductions, and human land use. The landscape 

must also be large enough to encompass the dynamics of 

most disturbance regimes that affect it—a task that is difficult due to the high variation of disturbance. Yet, despite 

its drawbacks, the HRV concept may well be indispensable to ecosystem management because it can be used to 

define limits of acceptable change and compare historical 

and current stand or landscape condition to prioritize for 

restoration treatments (Hessburg and others 1999; Swetnam 

and others 1999).

The HRV of landscapes can be quantified from three main 

approaches. The best approach is to obtain spatial chronosequences defined as sequences of maps from one landscape 

over many time periods. The second approach is to quantify 

HRV landscape characteristics by using vegetation maps 

from many similar, unmanaged landscapes taken from one 

or more time periods gathered across a geographic region 

(Hessburg and others 1999). This spatial series essentially 

substitutes space for time and assumes all landscapes in the 

series contain highly similar environmental, disturbance, 

topographical, and biological conditions (Pickett and others 1987). The third method involves simulating historical 

dynamics to produce a chronosequence of simulated maps 

to compute landscape statistics and metrics. Many spatially explicit ecosystem simulation models are available 

for quantifying HRV patch dynamics (Gardner and others 

1999; Keane and others 2004; Mladenoff and Baker 1999). 

The LANDFIRE national mapping effort (www.landfire.

gov) has simulated historical time series that can be used as 

reference in calculating departure of current from historical 

conditions, as described in this report.

Possible Assessment Criteria

The list of important landscape attributes that may be considered when prioritizing, planning, or designing treatments 

to restore whitebark pine is quite different at the landscape 
USDA Forest Service RMRS-GTR-279. 2012. 65

level than for other restoration scales. Many of the factors 

that govern whitebark pine status and decline act primarily at the landscape scale (Keane and others 1996), such as 

disturbance, climate, and seed dispersal. Management responses to these factors require careful evaluation. While 

most proactive management actions are implemented at the 

stand level, the location of stands to be restored will entirely 

depend on the landscape in which they occur. The following 

are some important factors that could be used to prioritize, 

design, and select landscapes to restore:

1. Disturbance

o Level of rust infection and mortality. The extent of 

blister rust infection and mortality is an important 

factor in determining the kinds of restoration actions 

for a given landscape. In short, the higher the rust 

infection and mortality levels, the greater the need 

for restoration action, such as creating openings 

through thinning, and planting rust-resistant 

seedlings. In these stands, cone productivity is 

greatly diminished, and whitebark pine is declining 

as a functional ecosystem component. However, 

under these conditions, surviving trees may 

have the highest blister rust resistance, yet seeds 

for these stands are less likely to be dispersed 

because of intense competition among nutcrackers, 

squirrels, and other seed-users (McKinney and 

Tomback 2007). As previously mentioned, stands 

with the highest levels of rust infection (greater 

than 90 percent) and mortality (greater than 50 

percent) are the best candidates for finding blister 

rust resistant trees, which can be designated plus 

trees and can be protected from seed predators and 

disturbance (Hoff and others 2001). Conversely, 

landscapes with low rust infection (less than 90 

percent of stands) may not be good places to look 

for plus trees, but they may be suitable for proactive 

restoration treatments, such as reducing competition 

from shade-tolerant competitors through thinning 

and by creating openings to encourage natural 

regeneration through nutcracker caching (Hoff and 

others 2001; Keane and Arno 2001). Landscapes 

with greater than 50 percent of the area having 

high whitebark pine mortality (greater than 50 

percent) should have high priority for restoration. 

At the same time, proactive treatment of healthier 

landscape should be considered, and even planting 

of rust-resistant seedlings, to create more resilient 

stands.

o Level of mountain pine beetle outbreak. The success 

or failure of restoration programs can be wholly 

dependent on the current level of mountain pine 

beetle on the landscape. Landscapes with evidence 

of impending or on-going mountain pine beetle 

outbreaks (patchy mountain pine beetle mortality 

or infestation) should be evaluated carefully before 

restoration is implemented. These stands may have 

the lowest priority for restoration actions such as 

silvicultural thinning or nutcracker openings to 

encourage seed caching (Keane and Arno 2001) 

because beetles in outbreak mode will kill many of 

the living whitebark pine trees that the restoration 

actions were designed to preserve. Conversely, 

landscapes that experienced major pine beetle 

epidemics in the past are good candidates for 

restoration through seedling planting, because of 

the lack of seed sources for regeneration and the 

open canopy conditions. Furthermore, we should be 

managing stand structure to mitigate future beetle 

outbreaks, as previously described. This entails 

maintaining multiple age classes within a stand or as 

a mosaic on the landscape.

o Recent occurrence of fire. A recent fire event might 

indicate that this landscape may not need treatment, 

or the landscape may need post-fire restoration 

treatments such as tree planting or site amelioration. 

A fire atlas (map of fire perimeters with burn dates) 

is essential for this assessment. If information on 

historical fire return intervals is lacking, managers 

need to consider that regenerating 2.5 percent of the 

total whitebark pine habitat type every 10 years is 

required to emulate a 400-year fire return interval 

to maintain the landscape within its historical range 

of variation over time. At 400 years, the long end of 

the fire return interval, most trees will be peaking in 

cone production. That would mean at a minimum, 

25 percent of the seral whitebark pine type should 

have burned since 1900 to be within the maximum 

historical fire return interval range (Morgan and 

Bunting 1989).

o Climate change. Many believe whitebark pine is 

one of the most at-risk ecosystems in the western 

United States and that climate change will affect the 

whitebark pine distribution most severely, especially 

forests at the lowest elevational range (Koteen 

1999; Romme and Turner 1991; Schrag and others 

2008). While whitebark pine can grow in warmer, 

drier climates (Arno and others 1993), its vigor, 

reproductive potential, and regeneration success 

will surely decline, and it may be outcompeted 

by other forest species moving up in elevation. 

Therefore, as a hedge against potential shifts in 

climate, and the need for whitebark pine to disperse 

to new elevations or latitudes, restoration actions 

should be implemented above the current local 

lower elevational limits of whitebark pine and at 

the northern limits of whitebark pine in order to 

maintain healthy forests (Schoettle and Sniezko 

2007; Tomback and Achuff 2010). Landscapes with 

topography that encompasses the full elevation 

range of whitebark pine might have higher 

potential for successful long-term restoration, while 

landscapes that have maximum elevations that are at 
66 USDA Forest Service RMRS-GTR-279. 2012.

the historical lower elevational limits of whitebark 

pine might be difficult to restore in the future.

2. Successional Status

o Landscape composition. The composition of the 

landscape is an important indicator of the need for 

restoration. A landscape that is comprised mostly 

of stands dominated by shade-tolerant species 

(specifically subalpine fir) might indicate the absence 

of wildland fire and the need to initiate restoration 

actions. Conversely, the number of stands dominated 

by shade-intolerants (early seral species, such as 

whitebark pine) might indicate that restoration 

treatments might not be required. Modeling exercises 

have indicated that landscapes with greater than 10 

to 20 percent of their area dominated by subalpine fir 

might be outside HRV and could be good candidates 

for initiating restoration activities (Keane 2001b). 

This threshold was estimated from simulation results 

for a landscape in north-central Montana. Vertical 

stand structure (seedling, sapling, pole, mature, 

and old growth, for example) is another indicator 

of successional stage; advanced stages have less 

structure than earlier seral stages. Landscapes 

composed primarily of stands in late seral stages 

(mature and old growth), especially if dominated 

by subalpine fir, should have a high priority for 

restoration. However, whitebark pine stands in 

the later stand structural stages might be used as a 

surrogate for the presence or abundance of coneproducing trees, which should be retained on the 

landscape. HRV concepts can be used as a reference 

to determine potential restoration thresholds based on 

stand structure.

o Landscape structure. The spatial patterns of stands 

comprising a landscape (patch distribution) can also 

indicate the status of important ecological processes. 

For example, landscapes composed of one or two 

patches (stands with same age class or vegetation 

characteristics) may need treatment to diversify and 

fragment the landscape (Keane and others 2002c). 

Conversely, landscapes with many fragmented small 

patches might need treatment to improve historical 

patch distributions. Landscape structure is usually 

described from a wide variety of landscape metrics 

that quantify size, shape, connectivity, contagion, 

and dimension of the landscape (McGarigal and 

Marks 1995). Reference conditions would be best 

taken from a simulated series of landscape histories 

where a small set of landscape metrics are used 

for comparison (Keane and others 2002a). We 

recommend that the indices of mean patch size 

(patch density), largest patch index, shape index, and 

contagion be used to match the native disturbance 

regime (Keane and others 2002b).

o Departure from HRV of landscape composition 

and structure. The current landscape composition, 

computed as area by patch type (cover type, 

structural stage, or the combination, for example), 

can be compared to an historical time series of spatial 

layers to determine departure. The current condition 

can be quantified from any number of sources, 

including digitized stand maps and maps developed 

from remotely sensed imagery. Temporally deep 

historical spatial chronosequences are rare for most 

of the western United States, so most historical time 

series are developed using simulation modeling. 

The national LANDFIRE project is creating maps 

of current conditions from satellite imagery and 

historical time series from the landscape simulation 

model LANDSUM (www.landfire.gov) (Pratt 

and others 2006). These historical time series can 

also be created from other landscape models such 

as SIMMPPLE (Chew and others 2003), FVSFFE (Reinhardt and Crookston 2003), and VDDT 

(Vegetation Dynamics Development Tool) (Beukema 

and Kurtz 1998). The comparison between current 

and historical is calculated using a departure index 

scaled from zero (totally departed) to 100 (exactly 

the same). The Fire Regime Condition Class (FRCC) 

mapped by the LANDFIRE project is derived from 

a departure index and can be used for this purpose. 

FRCC is an ordinal index from 1 (within HRV) to 3 

(outside HRV), and it is available in a 1 km2 national 

map (www.fs.fed.us/fuelman) and as a LANDFIRE 

map product at 30-m pixel resolution (www.landfire.

gov).

3. Seed Sources

o Distance. Local extinctions can occur if whitebark 

pine declines to an extent where seeds are not 

abundant and sources are not close enough to 

provide adequate regeneration. Maximum dispersal 

distances documented in the literature range from 

10 to greater than 30 km depending on geographical 

area and nutcracker population, but we feel 12 to 

15 km is a good conservative maximum distance 

to expect nutcrackers to re-establish a whitebark 

stand (Lorenz and others 2008; Tomback 2005). 

Landscape assessments should identify areas where 

local extinctions are possible (greater than 12 to 15 

km from a seed source) and prioritize these areas 

for regeneration treatments that involve planting. 

This can be done in a GIS using buffer analysis. 

Identified seed source areas should be assessed to 

evaluate if there are sufficient numbers of conebearing whitebark pine to provide the seed for 

regeneration. At least 20 to 50 cone-bearing trees 

per acre would be needed to be considered a good 

seed source (McKinney 2004).

4. Logistical Issues

o Transportation network. Critical for most restoration 

actions is a means to efficiently travel to the 

landscape to perform the treatments. Conducting 
USDA Forest Service RMRS-GTR-279. 2012. 67

prescribed burns and tree cuttings is best done if the 

treatment units are near roads or trails. However, 

wildland fire use (WFU; allowing lightning fires 

to burn under acceptable conditions) may not need 

extensive transportation networks because no active 

suppression is involved. Landscapes with roads in 

whitebark pine forests would receive a high priority 

and those with trails may rate lower in priority.

o Topography. The complexity, orientation, and aspect 

of the topography will dictate the type, intensity, 

and extent of restoration activities. Landscapes with 

gentle slopes, for example, will be much easier to 

restore than steep, dissected topography. Landscapes 

with deep snows may be inaccessible for restoration 

equipment during critical times of the year.

5. Management Issues

o Grizzly bear. Any landscape where grizzly bears 

frequent could be considered high priority for 

restoration, especially if whitebark pine mortality is 

high and subalpine fir stands are extensive (greater 

than 20 percent in area). Management activities, 

such as prescribed burning, in critical grizzly bear 

whitebark pine habitat may not be desirable because 

these actions might actually reduce whitebark pine 

cone production in the short term. Restoration plans 

often prioritize treating areas with available access, 

which could cause potential future conflicts when 

cone-producing trees are close to human activities. 

Restoration activities themselves also cause 

disturbance, which discourages bear use of the area 

(Mattson and others 2001). Restoration treatments 

often focus on reducing the effects of competing 

shade-tolerant tree species, but mixed species stands 

have higher squirrel populations and therefore more 

squirrel middens. While bears require large areas 

free from human activities, restoration treatments 

bring humans into the whitebark zone, may remove 

cone-producing whitebark pine in the short term, or 

may reduce the population of squirrels or the size 

of middens. On the other hand, whitebark pine may 

need extensive management to avoid extirpation in 

the long term (Mattson and others 2001).

o Land ownership and management direction. The list 

of possible restoration actions for a landscape would 

entirely depend on the ownership of the landscape 

and how that landscape is managed. Roadless areas 

on National Forests may have a different set of 

restoration techniques when compared with National 

Parks or state lands. Landscapes with restrictions 

that may reduce the efficacy of restoration measures 

might be less desirable. Landscape management 

concerns are often locally important and must be 

addressed in any prioritization effort.

o Wilderness. Wilderness and recommended wilderness 

lands are treated quite differently from other public 

lands and, as such, are a special case in management. 

Current wilderness policy with respect to whitebark pine 

restoration is detailed in the “Introduction” section.

o Planning stage. Landscapes that have completed 

burn plans could be some of the first to be restored, 

especially with wildland fire use or controlled 

wildfires. Those landscapes with completed NEPA 

analyses may also be considered high priority.

o Human disturbance—structures and activities.

Whitebark pine forests that are near areas or 

developments frequented by people, such as ski 

areas or popular hiking trails, may be undesirable 

for restoration if there is negative public opinion. 

However, proactive public education may be a winwin solution to this problem, actively engaging the 

public in understanding the reasons for whitebark 

pine resource management and even enlisting public 

support through “citizen science.” Interpretive 

information or other forms of public outreach at ski 

areas or at trailheads are good ways to inform the 

public about ecological challenges and potential 

solutions. Any restoration treatment may be made 

more desirable if it can also reduce fuels, improve 

ecosystem health, improve aesthetics, and have easy 

access.

Restoration Actions

Perhaps the most important restoration tool for landscape-level restoration applications is the use of controlled 

wildfires (CW). CW, which used to be called wildland fire 

use, prescribed natural fires, and “let burn” fires, are lightning-started fires that are allowed to burn under acceptable 

weather and site conditions that are specified in a fire plan 

(Black 2004). We feel the aggressive use of CW has the 

potential to be an efficient, economical, and ecologically 

viable method of restoring whitebark pine in many areas, 

especially wilderness. Landscapes where CW might be 

contra-indicated are those with few whitebark pine seed 

sources both near and distant, and in these places, planting is strongly advised. Otherwise, most CW will probably 

improve whitebark pine’s status and health if the fires are 

carefully monitored to avoid mortality of potentially rustresistant trees. However, we highly recommend that burned 

areas in landscapes with high blister rust infection (greater 

than 50 percent) and mortality (greater than 20 percent) be 

planted with apparent rust-resistant whitebark pine seedlings 

(discussed at the stand and tree scale).

Uncontrolled wildfires, or wildland fires that are actively suppressed, may also be a possible restoration tool at 

the landscape level. Large wildfires may be important for 

whitebark pine restoration in those areas of its range that 

historically experienced extensive fires in a given year, 

such as the northern Rocky Mountains of the United States. 

Conventional wisdom is that wildfires today may burn larger 

areas more severely than the past because of the buildup of 

fuel from fire suppression efforts (Ferry and others 1995; 
68 USDA Forest Service RMRS-GTR-279. 2012.

Van Wagtendonk 1985), but recent research has found that 

these large fires actually leave a mosaic of intensities and 

severities that are similar to historical conditions (Keane and 

others 2008a). Land managers and fire suppression management teams should view wildfires as a possible mechanism 

for restoring high-elevation systems and use ecologically 

based decision support tools to decide whether or not to let 

wildfires create potential restoration sites for whitebark pine. 

Moreover, wildfire rehabilitation teams should evaluate the 

level of cone production and rust/beetle mortality in whitebark pine stands surrounding these large wildfires to assess 

if planting putative rust-resistant whitebark pine is necessary 

to ensure adequate regeneration.

Management Concerns

Seed Dispersal and Large Burns

Large burns (greater than 1000 ha) favor whitebark pine 

regeneration because wind-dispersed seeds of its competitor species take longer to disseminate into the center of 

large burned areas than whitebark seeds that are cached by 

nutcrackers flying up to about 30 km to cache their seeds 

(Lorenz and others 2008; Tomback and others 1990). 

However, seed dispersal for wind-dispersed conifers, such 

as subalpine fir and Engelmann spruce, can be rapid with 

favorable prevailing winds, thus reducing the effectiveness 

of large burns (Tomback and others 1990). If the prevailing 

winds do not favor seed dispersal into burns, whitebark pine 

seed dispersal by nutcrackers can result in more rapid regeneration. Burn areas can be attractive to nutcracker caching 

(Tomback and others 1990), but whitebark pine on-site seed 

sources are often killed during wildfires. Trees are killed not 

only directly from fire effects, but also because fire-damaged 

trees often attract mountain pine beetles.

A major management concern may be that cone-production 

on or near the burned landscape might be insufficient for adequate regeneration of whitebark pine, because of high tree 

mortality and advanced successional processes. Between red 

squirrels cutting cones for storage in middens and Clark’s 

nutcracker predispersal seed predation, few seeds may remain for seed dispersal (McKinney and Tomback 2007; 

McKinney and others 2009; Keane and Parsons 2010b). If 

whitebark pine seed sources are sparse or in poor condition 

then large burns must be planted with rust-resistant whitebark 

pine seedlings to ensure restoration success. Furthermore, 

between climate change and past fire exclusion policies, 

the area burned by wildfires and CW fires will be extensive 

during the next few decades. It is critical that periodic assessments be conducted to determine if too many or too few 

whitebark pine forest communities are being burned. Again, 

a landscape rotation or mean fire return interval of 400 years 

can be used to identify important burning thresholds and targets. One further concern is that with the combination of 

deteriorating seed sources and climate change, temperature 

and moisture regimes may be less favorable for germination 

of whitebark pine seeds cached in stand-replacing burns, 

and survival of seedlings. These processes may already be 

at work and explain observations of delayed regeneration of 

large burns in northwestern Montana (Tomback 2008).

Decline in Cone Production and Effects on 

Seed Dispersal

An analytically based model depicts the series of processes that occur following the arrival of blister rust within 

a whitebark pine stand and culminates with the creation of a 

positive feedback loop resulting in continued whitebark pine 

community decline (McKinney and Fiedler 2010) (Figure 

4.14). The data to support this model were collected from 

2001 to 2006 in 24 forest sites that ranged in size from 2 

to 7 ha in the U.S. central and northern Rocky Mountains 

Figure 4.14. Analytically based model 

depicting the series of processes 

that occur following the arrival of 

blister rust within a whitebark pine 

stand (from McKinney and Fiedler 

2010).
USDA Forest Service RMRS-GTR-279. 2012. 69

(McKinney and Fiedler 2010). Blister rust initially invades 

the stand, and rust-induced tree mortality increases with 

time. The correlation between rust infection and tree mortality is positive but weak, because as rust kills the most 

susceptible trees, the proportion of infected trees levels off 

while mortality continues to increase. As mortality increases, 

live whitebark pine basal area declines sharply. The decline 

in live whitebark pine basal area has an effect on red squirrel habitat use that depends on tree species composition. As 

the proportion of total stand basal area that is comprised of 

whitebark pine declines, red squirrel habitat use increases. 

There is a strong negative correlation between the proportion of stand whitebark pine basal area and the proportion 

of total squirrel detections comprised of active middens. 

As the proportion of middens increases, pre-dispersal cone 

predation increases. Greater cone predation results in fewer available cones at the time of nutcracker seed dispersal. 

Basal area and cone production are strongly and positively 

correlated (r = 0.81); thus, as whitebark pine basal area declines, cone production declines in a near linear fashion. 

Cone production declines that are due to a loss of live basal 

area are exacerbated by squirrel predation in mixed species 

forests and even whitebark pine-dominant forests that are 

adjacent to recently burned sites (fewer cones produced that 

suffer greater predation pressure) resulting in substantially 

fewer cones available at the time of seed dispersal (late summer to early fall) (McKinney and Tomback 2007; McKinney 

and Fiedler 2010). 

Nutcrackers are highly sensitive to the available number (or density) of cones in a forest, and as nutcracker 

occurrence and seed dispersal behavior decline, regeneration 

opportunities decline (McKinney and others 2009). A lack 

of regeneration over time will eventually lead to a decline 

in mature, cone-producing trees. This begins the positive 

feedback loop whereby declining basal area leads to declining cone production, declining nutcracker seed dispersal 

activity, and ultimately, declining regeneration. Active management, such as planting rust-resistant seedlings, becomes 

a necessity at this point to prevent spiraling of the positive 

feedback loop to an end point of extirpation.

It is difficult to say exactly when in the previously described cycle of decline active management intervention is 

needed. Part of the uncertainty is due to differing management goals and priorities, and part is due to the complexities 

of habitat and landscape context of the forest in question. In 

the best of all worlds, proactive restoration would begin before decline is evident, helping to mitigate losses (Schoettle 

and and Sniezko 2007). Decisions regarding an acceptable 

level of cone production decline and uncertainty of seed 

dispersal need to be made first, however, and the analytical 

model may be applied here for that purpose (McKinney and 

others 2009). For example, when we set a cutoff probability 

of seed dispersal to 0.70 (we want to be sure that 70 percent 

of the seeds will be dispersed by nutcrackers), 94.7 percent 

of all study sites with seed dispersal observed were correctly 

classified by the model. The logistic equation in McKinney 

and others (2009) predicts that a whitebark pine forest has 

a seed dispersal probability greater than 0.70 with average 

cone production greater than 700 cones ha-1.

Based on previous estimates of nutcracker energy requirements and the results from the seed dispersal model, 

a threshold of 1000 cones ha-1 averaged over a given site is 

needed for a high likelihood of nutcracker presence at the 

time of seed dispersal. For example, the model predicts a 

nutcracker seed dispersal probability of 0.83 for a site with 

mean production of 1000 cones ha-1. The local spatial extent 

over which this magnitude of cone production must occur 

requires more detailed investigation. The estimate does, 

however, form a reasonably sound basis to begin to formulate whitebark pine management and restoration decisions.

If estimates of cone production are not readily obtainable 

for a given landscape, live whitebark pine basal area can be 

used instead as a predictor of cone production. Mean cone 

production was significantly correlated with mean basal area 

over the 24 sites sampled (r = 0.81). Graphical analysis of 

mean cone production plotted against basal area suggests 

that 5.0 m2 ha-1 defines the lower limit of mean live whitebark pine basal area needed to produce an average of 1000 

cones ha-1. Furthermore, research sites where nutcracker 

seed dispersal was never observed over a three-year period 

had mean live whitebark pine basal area of 1.58 (±se 0.78) 

m2 ha-1 (n = 7); sites with nutcracker seed dispersal observed 

in some years (and not in others) had mean live basal area of 

5.03 (±1.01) m2 ha-1 (n = 7); and sites with observations of 

nutcracker seed dispersal in all years had mean basal area of 

15.27 (±2.51) m2 ha-1 (n = 10). Therefore, we estimate that 

whitebark pine forests with a mean basal area around 5.0 m2

ha-1 will be able to produce approximately 1000 cones ha-1, 

at least in some years, and consequently attract and maintain nutcrackers through the critical period of seed dispersal. 

However, because there is substantial variability in cone 

production among sites, the proposed cutoff value should 

be interpreted cautiously and accompanied by a site-specific 

evaluation of conditions (McKinney and Fiedler 2009).

Landscapes with less than 5.0 m2 ha-1 of live whitebark 

pine basal area and producing fewer than 1000 cones ha-1

will require planting of rust-resistant seedlings, especially 

with further whitebark pine losses highly likely. For example, 

given the high levels of rust infection and tree mortality, and 

the low levels of live basal area documented in northwestern 

Montana, it is likely that many whitebark pine forests in that 

region are no longer sustainable without restoration planting. However, data show that sites that exceed the 5.0 m2

 ha-1 

threshold can still rely on nutcracker seed dispersal in some 

years, although these forests will lose whitebark pine over 

time as blister rust infection kills trees and damages canopies 

and as mountain pine beetle outbreaks continue. Managers 

are encouraged to identify such sites and use appropriate silvicultural treatments to increase nutcracker caching habitat, 

at least for the immediate future.

As an example, if a whitebark pine landscape has greater 

than 5.0 m2 ha-1 of live basal area, is at least 10 ha in area, 

and is not isolated from other whitebark forests, it could 

serve as a natural seed source for a restoration project. 
70 USDA Forest Service RMRS-GTR-279. 2012.

Removal (cutting) of competing shade-tolerant trees followed by prescribed burning at a location within 10 km of 

the whitebark seed source would likely attract nutcracker 

caching and increase the likelihood of natural regeneration 

(Keane and Arno 2001). Site-specific knowledge of whitebark pine forest attributes would also allow fire managers 

to make informed decisions regarding CW, which entails 

deciding when and where to allow lighting-ignited fires to 

burn. CW could be allowed to burn in subalpine forests 

where the probability of nutcracker seed dispersal is high 

and the potential for damage to humans and property is low. 

Finally, knowing which forests have whitebark pine basal 

area below 5.0 m2 ha-1 would allow managers to prioritize 

areas for planting with the limited number of rust-resistant 

seedlings available (Mahalovich and others 2006).

Here we have shown that specific forest stand conditions (proportion of stand basal area comprised of 

whitebark pine, total live whitebark pine basal area, and 

cone production) within a landscape are crucial elements in 

predicting the number of cones available for nutcrackers, 

nutcracker seed dispersal probability, and thus, the potential to contribute genetic material to future generations 

through natural regeneration. Natural regeneration, facilitated by restoration treatments, should include a higher 

proportion of rust-resistant individuals over time relative 

to the frequency of rust-resistance in parent trees because 

of a high mortality rate in susceptible trees. In some remote locations, the use of CW may be the best approach to 

whitebark pine restoration, given reasonably healthy seed 

sources. However, seedlings that are susceptible to blister 

rust have a poor chance of survival in areas of high blister rust infection levels (for example, Tomback and others 

1995), and the need to plant rust-resistant seedlings may 

be inevitable. Planting rust-resistant seedlings may well be 

the best strategy for spreading genetic resistance to blister 

rust as rapidly as possible and ensuring that whitebark pine 

will remain on the landscape.

Example: Restoration Decision Guidelines 

for Watersheds on the Caribou-Targhee 

National Forest

Jenkins (2005) recognized that several factors should 

be included in landscape-scale assessments (Table 4.6). Of 

greatest importance is the extent of whitebark pine forests 

that currently exist in the assessment area compared to the 

historical levels of whitebark pine. Those areas with small 

changes in whitebark pine distributions and abundance require less active restoration. A large decrease in abundance 

(estimated at greater than 20 percent of historical levels) 

indicates a greater need for restoration. Jenkins (2005) also 

recognized that in addition to whitebark pine abundance, 

changes in size class distribution should be considered. 

Areas that have decreases (greater than 20 percent) in historical size class distribution levels have a greater need for 

restoration. This comparison to historical ranges of whitebark pine abundance and size class distributions to current 

levels is consistent with the concepts of HRV (Keane and 

others 2002b; Landres and others 1999). Application of 

HRV to prioritize and design whitebark pine restoration 

efforts can be useful if interpreted in the appropriate ecological context (Keane and Karau 2010).

Stand Scale

The stand scale is the resolution at which most proactive management restoration efforts are targeted. A stand is 

defined here as an area of homogeneous vegetation composition and structural conditions, usually about 1 to 100 ha (2 

to 250 acres). The delineation of a stand in a spatial analysis 

environment (GIS) is usually called a polygon. Planning 

and prioritization should rarely be conducted at the stand 

level because the complex processes that control whitebark pine abundance and decline are best described at the 

landscape and broader scales. However, most proactive restoration treatments are usually designed and implemented at 

this stand level. In this report, landscapes are composed of 

stands that are described by the trees and undergrowth that 

grow within their borders, and trees are usually described 

by basal area, density, and timber volume by species and 

size classes. The undergrowth is often described as cover, 

height, and density by species and size class.

Assessments

Assessments performed at this scale would be for several purposes: (1) to determine the health and condition of 

the stand to rank it compared to other stands for restoration 

priority, and (2) to determine the condition of the stand to 

inform design of restoration treatment. Assessments at the 

stand level usually involve inventory or monitoring. Many 

inventory and monitoring systems can be used to sample 

stand attributes, including FIREMON (Lutes and others 

2006), FSVEG, and FFI (FEAT FIREMON Integration) 

(Lutes and others 2009). It is critical that any inventory or 

monitoring effort include an assessment of those factors 

that are contributing to whitebark pine decline, such as rust 

infection incidence, canopy kill, mountain pine beetle mortality, whitebark pine regeneration potential, and subalpine 

fir or other shade-tolerant species density and size classes. 

The WPEF methods for surveying whitebark pine are focused on health assessment of stands; using these methods 

and the variables described allows for meaningful comparisons among stands within and among geographic areas 

(Tomback and others 2005; www.whitebarkfound.org).

A multitude of variables can be used to describe stand 

conditions for assessing restoration concerns and designing 

appropriate management treatments. Previous fire history 

can be assessed by visual evidence within the stand such 

as fire scars on trees, age class structure of the stand, and 

charcoal in the soil. Successional status can be determined 

from the tree density by size class and species. The following are important stand attributes that may be considered in 

deciding how to treat a whitebark pine stand:
USDA Forest Service RMRS-GTR-279. 2012. 71

Table 4.4.1. Restoration Rating for Stands for the Targhee within HUC 1201. “SF” is subalpine fir, “WB” is whitebark 

pine, and “N/A” is not available. Numbers after “/” indicate weighting.

GB management 

emphasized

No GB 

management

Stand #

Recent stand 

replacing event1

event

Distance to seed 

source >10 km2

Successional status3

Human 

disturbance 

>.5 mile4

>174 BA and 

15-50% WBP5

Motorized 

access (miles)6

Blister rust7

Mountain pine

Beetle8

Stand score

Total restoration 

need score

1 No No SF/20 .65/10 Maybe/10 N/A Mod/10 Y/40 90 240*

2 | | SF/20 1/10 Maybe/10 N/A Mod/10 Y/40 90 240*

3 | | WB/0 .5/0 N N/A Mod/10 Adj/40 50 200

4 | | SF/20 .1/0 Maybe/10 N/A Mod/10 Adj/40 80 230

5 | | SF/20 .5/0 Maybe/10 N/A Mod/10 Y/40 80 230

6 | | SF/20 .6/10 Maybe/10 N/A Mod/10 Y/40 90 240*

7 | | SF/20 1-2/10 Maybe/10 N/A Mod/10 Adj/40 90 240*

8 | | SF/20 1-2/10 Maybe/10 N/A Mod/10 Adj/40 90 240*

9 | | SF/20 1-2/10 Maybe/10 N/A Mod/10 .8mi/20 70 220

10 | | LP/10 1-2/10 N N/A Mod/10 .9mi/20 50 200

11 | | SF/20 1-2/10 N N/A Mod/10 Adj/40 80 230

12 | | SF/20 1-2/10 Maybe/10 N/A Mod/10 .3mi/20 70 220

13 | | WB/0 1-2/10 N N/A Mod/10 .9mi/20 40 190

14 | | WB/0 2-3/10 N N/A Mod/10 1-2mi/20 40 190

15 | | WB/0 2-3/10 N N/A Mod/10 1-2mi/20 40 190

16 | | SF/10 2-3/10 Maybe/10 N/A Mod/10 1-2mi/20 60 210

17 | | WB/0 2-3/10 N N/A Mod/10 1-2mi/20 40 190

18 | | WB/0 2-3/10 N N/A Mod/10 1-2mi/20 40 190

19 | | LP/10 2-3/10 N N/A Mod/10 1-2mi/20 50 200

20 | | WB/0 3-4/10 N N/A Mod/10 2mi/20 40 190

21 | | LP/10 2-3/10 Maybe/10 N/A Mod/10 1-2mi/20 60 210

22 | | SF/20 2-3/10 Maybe/10 N/A Mod/10 1-2mi/20 70 220

23 | | SF/20 2-3/10 Maybe/10 N/A Mod/10 1-2mi/20 70 220

24 | | WB/0 2-3/10 N N/A Mod/10 1-2mi/20 40 190

25 | | SF/20 2-3/10 Maybe/10 N/A Mod/10 1-2mi/20 70 220

26 | \/ LP/10 3-4/10 Maybe/10 N/A Mod/10 2.5mi/20 60 210

27 | Yes/10 SF/20 .5/0 N; CSE N/A High/20 Y/40 90 240*

28 | Yes/10 WB/0 .65/10 N; CSE N/A High/20 Y/40 80 230

29 | Yes/10 WB/0 .5/0 N; CSE N/A High/20 Y/40 70 220

30 \/ No WB/0 1-2/10 N N/A Mod/10 .6mi/20 40 190

“CSE” indicates stands with a stand exam.

* indicates highest rated stands.

Ratings are as follows:

1

Natural regeneration within 10 yrs = 0, regeneration within 20 yrs = 10, regeneration >20 yrs = 20

2

Distance <10 km = 0, Distance >10 km = 10

3

Whitebark pine climax = 0, climax with high mortality = 1, whitebark pine >40 percent = 0, lodgepole dominant = 10, subalpine fir 

dominant = 20

4

Potential for human disturbance >.5 mi = 0, < .5 mi = 10

5

Not capable of meeting or meets and is stable = 0, potentially but not currently meets = 10, meets but treatment needed to maintain = 

20

6

Accessibility poor = 0, accessibility fair = 10, accessibility good = 20

7

Blister rust infection low = 0, rust infection moderate = 10, rust infection high = 20

8

Mountain pine beetle low and stable = 0, beetle high or increasing within 1-3 mi = 10, high or increasing in or adjacent = 20
72 USDA Forest Service RMRS-GTR-279. 2012.

•	 Disturbance History

o Blister rust infection and mortality. Treatment 

objectives for these sites should emphasize rustresistant whitebark pine regeneration rather than 

cone production. This is accomplished by treatments 

that favor remaining healthy trees (which could be 

rust resistant), and where blister rust infection levels 

are high, planting of seedlings from rust-resistant 

parent trees. Rust infection and mortality levels can 

be assessed using the WPEF rust sampling methods 

(Tomback and others 2005), but other inventory 

systems, such as FIREMON (Lutes and others 

2006), FFI (Lutes and others 2009), and FSVEG, are 

available to assess rust damage.

o Mountain pine beetle damage and mortality. Although 

mountain pine beetles are native to whitebark pine 

ecosystems, outbreak levels should be quantified 

to maximize the success of restoration treatments; 

many treatments can be rendered ineffective if they 

are followed by mountain pine beetle infestations. 

Some treatments, such as thinning and burning, 

actually attract mountain pine beetles, which can then 

kill the same whitebark pine that have been favored 

by treatments. The standard inventory techniques 

mentioned above are available for estimating beetle 

levels and damage.

o Time since last fire. It is important to know if the time 

since last fire has been excessively long (greater than 

one fire rotation) or past the mean historical firefree interval (greater than mean fire return interval), 

especially on seral whitebark pine sites, because 

wildfires can be used as restoration tools. If the stand 

has been burned within the last century, then it is 

doubtful that it would need immediate restoration 

actions unless post-burn whitebark pine recovery 

was hampered by blister rust or a lack of nutcracker 

caching and a need for planting is indicated. We 

recommend planting phenotypically rust-resistant 

seedlings in recently burned areas where the blister 

rust incidence in the surrounding seed source is 

greater than 50 percent or if losses to mountain pine 

beetle are severe. In contrast, climax whitebark pine 

communities are self-replacing over time in the 

absence of fire and other disturbances.

o Fire regime and history. Determining fire regime 

and historical fire intervals for any given stand will 

provide guidance as to fire regime characteristics and 

successional dynamics. Some stands may be prone to 

non-lethal surface fires that maintain whitebark pine 

dominance and kill subalpine fir, and the frequency 

of these fires could be used to craft an appropriate 

restoration action.

•	 Successional Status

o Site type. Climax whitebark stands will be dominated 

by whitebark pine or codominated by whitebark 

and other conifers depending on site harshness. 

Generally, the drier and colder the site, the more 

dominant whitebark pine (Arno 2001). These climax 

stands usually occur at the highest whitebark pine 

elevations, but also may occur on particularly 

wind-swept or otherwise droughty sites where 

other tree species struggle to survive. In geographic 

or topo-edaphic regions where whitebark pine is 

one of the indicated climax species, succession to 

more shade tolerant tree species is not a concern. 

If mortality in climax stands due to blister rust 

and bark beetles is high (greater than 50 percent), 

managers may consider planting whitebark pine to 

meet appropriate forest cover objectives established 

during land management planning, especially if 

seedlings have some degree of rust resistance. In 

stands where whitebark pine is seral (seral whitebark 

pine types, see “Ecology” section), the successional 

progression causes the whitebark pine to be replaced 

by more shade-tolerant tree species (primarily 

subalpine fir and Engelmann spruce). The greater 

the representation of the shade-tolerant species, 

the greater the decline of more seral species such 

as whitebark pine. Succession is one of the three 

major factors causing the decline of whitebark pine 

throughout its range (Tomback and Achuff 2010; 

Tomback and others 2001a).

o Seral stage. Managers may consider treating stands 

with low to moderate representation of subalpine 

fir and spruce (less than 50 percent basal area) 

if this meets with other management objectives. 

Treating stands earlier in the successional process 

could reduce loss of the whitebark pine component, 

possibly increase cone production, and decrease the 

likelihood that the stand will support a crown fire that 

will kill cone-bearing whitebark pine. Any stand with 

greater than 50 percent basal area in subalpine fir and 

Engelmann spruce should have a high priority for 

treatment, especially if the landscape is composed of 

greater than 20 percent subalpine fir dominated stands 

by area. Stands with high densities of subalpine fir in 

the understory (greater than 2500 trees ha-1) should 

also be prioritized for treatment.

•	 Other Ecological Factors

o Distance to seed source. Stands that are experiencing 

high levels of whitebark pine mortality due to blister 

rust, beetles, wildfire, or succession and that are 

greater than 12 to 15 km (general maximum distance 

to expect nutcrackers to re-establish a whitebark 

stand) from a productive whitebark pine seed source 

should be a high priority for treatment (for example, 

Lorenz and others 2008). Further decline of the 

stand might result in a local extirpation. Restoring 

whitebark pine in this situation may require planting 

since so many of the cone-bearing trees are lost.
USDA Forest Service RMRS-GTR-279. 2012. 73

•	 Management Issues

o Red squirrel middens. Grizzly bears obtain whitebark 

seeds from squirrel middens. In general, squirrels and 

their middens are more abundant in stands with high 

basal areas of mixed conifer species that produce 

more constant supplies of squirrel food compared to 

pure whitebark stands that produce highly variable 

seed crops (see “Squirrels” section). Midden size and 

probability of occupancy decrease with increasing 

elevation (Mattson and Reinhart 1997). Based on 

optimum conditions for bear use of squirrel middens, 

Mattson (2000) recommended an overall forest basal 

area greater than 40 m2 ha-1 with whitebark basal 

area representing 15 percent to 50 percent of the total 

basal area. In the GYA, grizzly bear use of whitebark 

pine seeds increases with increasing squirrel densities 

and decreases with increasing whitebark pine basal 

area. Maximum bear use occurs at relatively low 

whitebark pine densities (basal area of 3 to 15 m2

ha-1). Optimizing stand conditions for red squirrel 

midden production for grizzly bear use is somewhat 

at odds with optimum stand conditions for whitebark 

pine. Cone production is relatively low in stands 

younger than 100 years of age and reaches peak 

levels soon after. Moderate levels of cone production 

persist in stands 300 to 400 years old (Weaver and 

Forcella 1986). Conditions that optimize squirrel use 

should occur when the whitebark pine trees in the 

stand are at prime cone-producing age (100 to 300 

years).

o Grizzly Bears. Grizzly bear foraging in whitebark 

pine will suffer from the removal of cone-producing 

whitebark pine, reduction of squirrel densities, or 

reduction in the size of squirrel middens (Mattson 

and others 2001). Restoration efforts should minimize 

impacts on these factors, but Podruzny and others 

(1999) preferred a no action approach, stating “we 

encourage caution in the management of whitebark 

pine habitats.” To prevent further loss of whitebark 

habitat and seed-producing trees in the grizzly 

bear’s range, cone harvesting or use of managementprescribed fires in the whitebark pine zone is 

discouraged. Bears avoid areas with on-going human 

activity, such as stand preparation for restoration 

activities. Management of whitebark pine forests for 

grizzly bears should emphasize maintaining large 

secure areas of diverse habitat types supporting stable 

numbers of whitebark pine trees and squirrels.

Restoration Actions

Wildland fire is the keystone disturbance that shapes most 

seral whitebark pine communities, so restoration treatments 

should be designed at the stand level to emulate fire’s historic effects on the landscape (Keane and Arno 2001; Perera 

and others 2004). While prescribed fire is the obvious tool, 

mechanical cutting treatments can also be effective in accessible areas. Properly designed silvicultural thinning can 

simulate the effect of mixed severity and non-lethal surface 

fire in whitebark stands (Keane and Arno 2001). Treatment 

unit sizes and shapes should be similar to the patterns left 

by past fires, but must consider the amount and condition of 

available whitebark pine seed source in surrounding stands 

(Keane and Parsons 2010b). Treatments that create large 

areas for whitebark pine regeneration should be avoided if 

there is little seed available for caching unless planting rustresistant seedlings is possible (McKinney 2004).

Whitebark pine is regenerated almost exclusively from 

Clark’s nutcracker seed caches. Therefore, restoration 

treatments that emphasize regeneration should optimize 

conditions that attract Clark’s nutcracker caching, or if not 

possible, plant seedlings instead. The optimum habitat for 

whitebark pine regeneration appears to be recently burned 

areas, because nutcrackers readily cache seeds in these 

open areas, and whitebark pine usually regenerates rapidly 

as a pioneering species under these conditions (Tomback 

and others 1990; Tomback and others 2001c). Burn patches 

greater than 5 to 10 acres were found to be attractive to 

Clark’s nutcrackers (Norment 1991; Tomback and others 

2001c). Whitebark pine seedling survival depends on many 

factors, but the lack of competition, and the protected microsite conditions that nutcrackers select appear to be the 

most important (Izlar 2007; McCaughey and others 2009).

Basically, two major types of restoration treatments 

are best implemented in combination at the stand level: 

prescribed burning and mechanical cuttings. Other minor 

treatments can be used to augment or complement the two 

major treatment types. Most restoration treatments are 

designed to reduce or eliminate competing species and 

increase the regeneration opportunities for blister rust-resistant whitebark pine seedlings. Again, the primary objectives 

of these proactive restoration treatments are to: (1) mimic 

some historical disturbance process, mainly wildland fire, 

(2) facilitate whitebark regeneration and cone production, 

and (3) create optimum nutcracker caching habitat. Two 

sources are available as detailed references for evaluating, 

designing, and implementing whitebark pine treatments. 

Keane and Parsons (2010a, 2010b) summarized results of 

a 15-year whitebark pine restoration study by treatment 

across five diverse sites. Keane and Arno (2001a) presented 

additional summarized material that can be used for the 

same purpose.

Mechanical Cuttings

Mechanical cuttings are treatments that manipulate the 

stand by removing trees (Figure 4.15). It is important to note 

that traditional silviculture has limited effectiveness in these 

high mountain stands because of the severity of the site, 

unique autecology of whitebark pine, and bird-mediated 

seed dispersal (Keane and Arno 2000). Novel silvicultural 

strategies that are tailored to individual stands are needed to 

address restoration concerns in whitebark pine (Waring and 

O’Hara 2005). In general, most cuttings should attempt to 
74 USDA Forest Service RMRS-GTR-279. 2012.

eliminate subalpine fir and other shade-tolerant competitors 

while enhancing whitebark pine. Thinnings can be used to 

improve the health of potential cone-producing whitebark 

pine, while other cuttings can be used to create fuelbeds to 

support prescribed burning activities. Usually, mechanical 

cuttings are only effective when treated stands are in close 

proximity to roads and are easy to work (gentle slopes, few 

rocks, and few wet areas, for example).

Six types of mechanical cuttings are being used in restoration treatments for whitebark pine. Keane and Parsons 

(2010b) created nutcracker openings in successionally 

advanced subalpine fir stands with healthy and dying, rustinfected whitebark pine (Figure 4.16). Nutcracker openings 

are a cutting treatment that attemps to mimic patchy, mixed 

severity fires. All trees except whitebark pine are cut in these 

openings. The size and shape of these cut areas may vary, 

but they can be anywhere from 1-30 acres based on a study 

by Norment (1991) who found that nutcrackers appeared to 

favor burn patches less than 15 ha in size. Other cutting treatments include group selection cuts, where all trees except 

whitebark pine are cut (group selections can be nutcracker 

openings), and thinnings where all non-whitebark pine trees 

below a threshold diameter are cut (Burns and others 2008; 

Chew 1990; Eggers 1990). Girdling subalpine fir trees has 

also been attempted on some restoration efforts because it 

is a cheap, rapid means of killing competing subalpine fir 

(Jenkins 2005). However, to be effective, the girdling has 

to be done below the lowest live branches or those branches 

can form new boles. Girdling also leaves a large portion of 

the tree biomass on the site, which could provide fuel that 

fosters high severity wildfires that could kill the whitebark 

pine trees being restored. Daylighting (cutting of shade-tolerant competing species in a circle around whitebark pine 

trees) has been gaining favor among managers because it 

is cheap and easy, but there is little research on its effectiveness. One last cutting treatment is a fuel augmentation 

or fuel enhancement treatment where subalpine fir trees are 

directionally felled to increase fuel loadings and fuelbed 

contagion (Keane and Arno 1996, 2001). Keane and Parsons 

(2010a) found this treatment highly effective for facilitating 

prescribed burning.

It is important to reduce or remove the slash from the 

treatment area to (1) allow nutcrackers access to the ground 

for caching (Keane and Parsons 2010b), (2) reduce potential mortality from Ips spp. beetles (Baker and Six 2001), 

and (3) reduce the severity of unplanned wildfires (Keane 

and Arno 2000). This may be accomplished by (1) piling the 

slash and then burning the piles, (2) whole tree skidding to 

a landing that removes the boles and branches from the site, 

or (3) augmenting the cutting with a prescribed fire. Waring 

and Six (2005) found that Ips spp. beetles from slash piles 

move out and kill whitebark pine trees after one year. Cutting 

treatments can be offered as commercial timber harvests if 

(1) the trees are large enough, (2) the area is accessible by 

road, and (3) there is a market for the timber. Often, land 

management agencies have implemented cutting treatments 

using outside funding from various foundations or institutions because of the low timber value in treated stands.

Keane and Parsons (2010b) found that lodgepole pine 

trees could be left on site if they occur in low densities (less 

than 20 trees ha-1). Whitebark pine can compete with lodgepole pine on most upper subalpine sites with acceptable 

whitebark pine regeneration and growth providing that overstory lodgepole pine cover is low (less than 50 percent) (Arno 

and Hoff 1990; Keane and Parsons 2010b). Elimination of 

shade-tolerant competitors is the most important requirement of any cutting, and it is critical that the cone-bearing 

trees are eliminated first. Subalpine fir can have frequent 

cone crops with numerous seeds that will create dense fir 

stands. The most effective cutting treatments will be those 

that eliminate the most subalpine fir trees, starting with the 

cutting of cone-bearing trees first and then eliminating the 

carpet of fir regeneration. The presence of residual subalpine fir seedlings and saplings after a cutting treatment can 

shorten its life span and render it ineffective after a short 

time. The implementation of a prescribed burn after a cutting 

treatment can kill the understory subalpine fir and make the 

treatment effective longer.

Figure 4.15. Mechanical cutting used for restoring whitebark 

pine stands.
USDA Forest Service RMRS-GTR-279. 2012. 75

Figure 4.16. An 

example of 

nutcracker openings, 

a mechanical 

treatment used by 

Keane and Parsons 

(2010b) to mimic 

patchiness of mixedseverity fires.

Prescribed Burning

Prescribed burning may be the most desirable treatment 

because it best emulates wildland fire regimes (Figure 4.17), 

but it is also the most difficult and risky treatment to 

implement. Prescribed burns can be implemented at three intensities to mimic the three types of fire regimes common in 

whitebark pine forests (see “Fire Regimes” section). The primary objective of low-intensity prescribed fires is to kill the 

subalpine fir understory and perhaps the fir overstory and to 

preserve the whitebark pine component. Moderate-intensity 

prescribed burns can be used to mimic mixed-severity fires 

where passive crown fire behavior is common as dense subalpine fir crowns are torched, and these passive crown fires 

can burn patches of variable size depending on wind, canopy 

contagion, and fuel moisture conditions. A high-intensity 

prescribed burn is difficult to apply because it is usually implemented as a running or active crown fire that is difficult 

to control. However, this type of severe burn creates patches 

that are so large that seeds of whitebark pine competitors are 

unable to disperse into the center, allowing whitebark pine 

regeneration decades of competition-free growth after they 

have germinated from seeds cached by nutcrackers.

The ignition method for lighting the prescribed fires is important in the upper subalpine whitebark pine ecosystem. In 

previous restoration efforts, the prescribed fires were ignited 

using strip head-fires where the strip width was increased if 

higher fire intensities were desired. However, some study 

sites were too moist so they were burned with very wide 

strips. Keane and Arno (2000) used both the terra-torch and 

heli-torch in their study and burned large areas with the target 

high intensities, but these tools may not always be available (Figure 4.18). That leaves hand-held drip torches as the 

Figure 4.17. Prescribed burning in whitebark pine (Keane and 

Parsons 2010b).

primary ignition technique, and, to be effective, these ignitions should be attempted under dry conditions, especially 

if high-intensity fires are the objective of the burn. Another 

way to achieve high-severity prescribed fires is to implement multiple prescribed burns where two or three burns are 

implemented in the same stand over 5 to 10 years, provided 

there are sufficient fine fuel accumulations.
76 USDA Forest Service RMRS-GTR-279. 2012.

We recommend a fuel enhancement cutting that is implemented one year prior to a prescribed burn to ensure 

that burn objectives are fully realized (Figure 4.19) (Keane 

and Parsons 2010b). The addition of cured slash to discontinuous fuelbeds improves burn effectivness by providing 

additional fine fuel to: (1) aid fire spread into all areas of 

the stand, and (2) augment quickly drying fine fuel loadings 

so the burn can be implemented under moist conditions. 

Prescribed burns have a greater coverage and higher severity in stands where the fuels were enhanced (Keane and 

Arno 2001). Fuel enhancement is easy, cheap, and relatively quick, and enhancements can be done by timber crews, 

fire crews or contractors. Keane and Parsons (2010b) also 

found that shrub and herbaceous fuels were much drier after the first hard frost in late summer or early autumn. This 

frost kills the aboveground foliage that allows the plants to 

take water from the soil so the entire plant structure can dry 

sufficiently for burning.

Planting

As whitebark pine continues to decline across its range, 

there will be fewer seeds produced and available for nutcracker caching, resulting in fewer caches across the 

landscape, which in turn will reduce potential whitebark 

pine regeneration. Furthermore, those seeds produced in 

damaged stands are highly sought after by pre-dispersal 

seed predators, especially pine squirrels but also nutcrackers, leaving few seeds for nutcracker caching (McKinney 

and others 2009; McKinney and Tomback 2007). In high 

rust mortality areas, there may not be sufficient seeds to 

naturally regenerate whitebark pine and planting may be 

the only option.

Trees should only be planted from seed collected 

from “plus” trees known to be rust-resistant—identified 

by seedling progeny in rust screenings—or at least from 

phenotypically rust-resistant cone-bearing trees that are 

healthy with 30 percent or more live-green crown in otherwise highly rust-infested stands. Once seeds are available 

from seed orchards, cone collections should shift from 

the field to the orchards, which have been designed for 

improved blister rust resistance, broad adaptability, and 

minimal inbreeding. It may be beneficial to plant whitebark 

pine on a variety of sites and to refine planting guidelines 

for a specific geographic area or stand condition that will 

optimize survival and growth of future plantings.

Scott and McCaughey (2006) and McCaughey and 

others (2009) have developed more detailed, extensive 

planting guidelines. On the broad scale, planting should be 

done on a variety of sites, including the more productive 

seral sites. When practical, planting crews should attempt 

to remove non-whitebark conifers to make planting more 

effective in the long term. Based on ecological and physiological information, planting trials, and experience in the 

northern Rocky Mountains, they recommended the following guidelines be included in planting prescriptions:

Figure 4.18. Prescribed fire ignition is being implemented in a 

whitebark pine restoration site using the terra-torch.

Figure 4.19. Fuel enhancement cutting used to augment the 

fuelbed to widen the prescribed burning window and 

allow fire to burn to more of the restoration stand.
USDA Forest Service RMRS-GTR-279. 2012. 77

• Reduce overstory competition to increase light and day 

length to improve the effective growing season.

• Reduce most understory vegetation, especially grasses 

and sedges, to reduce competition for available soil 

moisture. However, sparse vegetation and particularly 

grouse whortleberry may provide some shade, retain 

moisture, and provide other benefits.

• Avoid planting in swales or frost pockets; consider the 

topographic position as well as the actual planting spot. 

Young whitebark pine seedlings do not appear to be 

frost hardy during the growing season. Ridge tops or 

exposed slopes are suitable.

• Provide shade and protection for newly out-planted trees 

to improve water utilization and to reduce light intensity 

and stem heating. Planting by stumps or other stationary 

shade is important.

• Plant where there is some protection from heavy snow 

loads and drifting snow. Stumps, rocks, and large logs 

are favorable microsites

• Do not overcrowd out-planted trees to avoid long-term 

inter-tree competition. Open grown trees have the largest 

crowns and produce the most cones. Tree form is not 

as important because the purpose is to establish trees 

for long-term regeneration, cone production purposes, 

aesthetics, and a variety of other reasons that do not 

include timber production. Adjust spacing guides based 

on expected survival. At 50 percent survival, planting 

density should be 6.1 m by 6.1 m (20 ft by 20 ft), 

producing 247 live seedlings ha-1 (100 acre-1).

• Plant when there is adequate soil moisture. Summer and 

fall outplanting have been successful, thereby avoiding 

the need for long expensive snow plows and delayed 

entry due to heavy spring snow loads.

• Plant large, hardy seedlings with good root development.

Whitebark pine seedlings take five to seven years to become fully established and start significant height growth 

(McCaughey and Tomback 2001). Perkins (2004) found that 

grouse whortleberry has a positive effect and upland sedges (Carex spp.) have a negative effect on the growth and 

survival of planted whitebark pine seedlings (Tomback and 

others 1993). Planting spot selection should be adjusted to 

take advantage of this information.

It may be useful to inoculate whitebark pine seedlings 

with ECM fungi for survival in nature since whitebark 

pine shares a complex, mutualistic ecological relationship with various species of ectomycorrizhae (Mohatt and 

others 2008; Read 1998) (see “Introduction” section). Preassessment of soils for the presence of appropriate native 

ECM fungi can be accomplished through use of bioassay 

techniques (planting seedlings in soils to be tested under 

greenhouse conditions). Inoculation of nursery seedlings 

with native fungi should be considered when soils lack appropriate ECM fungi and it is unlikely they will be imported 

in a timely manner (Brundrett and others 1996; Khasa and 

others 2009). Areas at high risk for absence of ECM fungi 

for whitebark pine are: ghost forests, severe burns, and species shift areas (not previously in whitebark pine). This is 

particularly true for areas a long distance from an inoculum 

source with few/no animal vectors present. The use of siteadapted host specific native fungi that occur with whitebark 

pine as inoculum is highly recommended. This excludes the 

use of commercial inoculum containing generalist fungi or 

those for/from lodgepole pine, spruce, fir, and other conifers. 

Inoculation and colonization of whitebark pine seedlings 

with native fungi has been successful under greenhouse 

conditions (Cripps and Grimme 2010). Suillus species have 

been used to successfully regenerate stone pines in Europe 

for 50 years (Weisleitner personal communication) and 

Suillus spp. were the most vigorous colonizers for whitebark 

pine in greenhouse studies (Cripps and Grimme 2010). The 

goal of inoculation is not to enhance growth of the pine, but 

to increase its survival rate and overall health. Inoculated 

seedlings should be subsequently monitored for colonization 

and survival. Planting trials using whitebark pine seedlings 

inoculated with native fungi were initiated in 2010.

Management Concerns

Scorching and wounding of trees can weaken trees and 

expose them to further damage by attracting mountain pine 

beetles, even at endemic beetle population levels. Managers 

should avoid scorching and wounding of 6 inch diameter 

breast height (DBH) and larger whitebark pine trees during 

restoration treatments. Changes in microclimate that occur 

when adjacent trees are removed can also stress whitebark 

pine in the short term and make them more susceptible to 

mountain pine beetle attack (Baker and Six 2001). Managers 

should protect high-value trees, which are those both bearing cones and exhibiting phenotypic blister rust resistance, 

as discussed in the “Tree Scale” section. If active outbreaks 

of mountain pine beetle are occurring locally, or if beetle 

populations are increasing, managers may consider delaying 

the restoration treatments until the outbreak is over.

There is little information available documenting the release of whitebark pine after the removal of any competition. 

Keane and others (2007a) conducted a limited release study 

based on only 48 trees in Montana, United States, and found 

that the magnitude of release after surrounding competing 

trees were cut was dependent on pre-cut tree density, tree 

age, and tree size. Basically, the youngest, largest trees in 

dense stands had the greatest potential for release and saplings older than 70 to 100 years may not release following 

treatment. Keane and Morgan (1994a) found that most of the 

apparent advanced regeneration in mature whitebark pine 

stands was quite old (greater than 100 years). Moreover, the 

understory regeneration had a wide range—from 30 to 270 

years of age for trees less than 1 inch DBH. It is doubtful that 

all seedlings and saplings will release following a treatment 

to remove competition. Designing restoration prescriptions 

to release whitebark pine is risky since only a few of the 

youngest, most vigorous trees will release, but the majority 

of older understory regeneration may not have the capacity 
78 USDA Forest Service RMRS-GTR-279. 2012.

to release. If release cuttings are desired, we suggest that the 

age structure of the understory be assessed to evaluate the 

potential for release (Keane and others 2007a).

The likelihood and rate of natural regeneration establishment depends primarily on the abundance of seed sources, 

the proximity of those seed sources to treated area, and the 

harshness of the site. Productive sites with abundant adjacent seed sources will likely establish natural regeneration 

within 10 years. However, recent studies and observations 

(Tomback 2008) suggest that areas with limited seed production will have limited natural regeneration, especially 

during warming temperature trends. Planting is the indicated treatment on these disturbed sites because it can increase 

rust resistance by using seedlings from suitable seed sources 

with the highest known levels of resistance.

Previously, planting success for whitebark pine was quite 

low due to the lack of guidelines and experience in these 

high-elevation systems. However, current efforts are showing great promise, and the Scott and McCaughey (2006) 

guidelines should help increase the survival of planted 

whitebark pine seedlings. There are some factors that might 

influence planting success:

• Snow. Heavy snow loads may harm or break seedlings, 

and the creep and glide of these heavy snow packs 

downslope could pull seedlings from the ground (Holler 

and others 2009). Seedlings should be planted near 

stable microsites (logs and stumps, for example). Heavy 

snow can also decrease the growing season because of 

late melt dates (Keane and Parsons 2010a).

• Sun. Insolation can kill many planted seedlings, but this 

can be mitigated with the selection of microsites that 

provide at least partial shade in planting sites.

• Disease. Damping off fungus occurs in deep duff and 

decomposing organic material.

• Competition. Grass competes with whitebark pine 

seedlings; seedlings should not be planted next to 

grass clumps or in gramminoid tussocks. Whitebark 

pine should not be planted under closed or semi-closed 

canopies, or on sites near other conifers.

Here are some other precautions that managers should take 

when designing stand-level restoration treatments:

• Where cone-producing whitebark pine need to be 

released from competition to maintain adequate 

whitebark presence in the stand, emphasize removing 

competing trees within one to one-half of dominant tree 

height around individual or small groups of whitebark 

pine.

• Emphasize restoration treatments that minimize the 

mortality of whitebark pine, especially cone-bearing 

trees. If prescribed burning is needed, emphasize 

burning in stands that currently have low whitebark 

basal area (0 to 1 m-2 hectare-1 or 0 to 5 ft-2 acre-1). 

Consider using preventive bark beetle treatments (see 

“Tree Level” section).

• If openings need to be created to attract nutcracker 

caching, emphasize keeping them relatively small (50 to 

100 m diameter) to optimize bird caching and provide 

sunlight to promote whitebark regeneration.

• Emphasize removal of many non-whitebark conifers 

as other management considerations will allow. This 

would reduce the competition experienced by individual 

whitebark pine of all ages and could reduce the 

likelihood of a stand-replacing fire.

• If possible, coordinate regeneration treatments with a 

good cone crop.

• Consider that many small understory whitebark pines 

are old and appear suppressed (poor growth, gray bark, 

irregular shaped bole) and these trees are unlikely to 

become cone-bearing, even with removal of competition 

(Keane and others 1994).

• Design regeneration treatments that minimize the 

potential for seeding from other tree species (i.e., large, 

stand-replacing fires upwind from seed sources).

If grizzly bears frequent the treatment area, then the following are some suggestions:

• Emphasize management that maintains or restores area 

in cone-bearing whitebark pine where possible. Consider 

controlling natural fires that may burn cone-bearing trees 

or protect these mature whitebark pine trees using fuel 

treatments, and avoid harvesting any whitebark pine.

• Prioritize management of habitat for red squirrels 

in areas that are capable of supporting cone-bearing 

whitebark pine.

• Protect areas that may be providing key habitat for 

bears, especially those areas where whitebark pine is 

limited due to losses from fire, bark beetle or succession.

• Emphasize maintaining cone-bearing whitebark pine 

in areas that are farthest from human disturbances. 

Avoid restoration treatments that create access that may 

increase human use of whitebark areas.

• Avoid restoration activities in whitebark pine forests 

when bears are most likely to be using them (last week 

in August through mid-November). Consider allowing 

treatments to occur if surveys for bears show that the 

area is not currently being used by bears or if area cone 

crops are known to be light.

Example

This example was taken from a treatment unit located 

at Beaver Ridge, Clearwater National Forest (Figure 4.20a) 

that was included in a whitebark pine study (Keane and 

Arno 1996, 2001; Keane and Parsons 2010b). The study is 

extensively detailed in Keane and Parsons (2010b) and the 

following is a summary of that discussion. The treatment is 

a moderate intensity prescribed burn with fuel enhancement 

(Unit 5A) (Figure 4.20b).
USDA Forest Service RMRS-GTR-279. 2012. 79

The Powell Ranger District wrote a comprehensive 

“District-Wide whitebark pine restoration integrated analysis” in May of 1997 and included research in their planning 

effort. They selected two areas for treatment: the Blacklead 

Mountain site and Beaver Ridge site in the fall of 1997. A 

request for comment was mailed to interested people in May 

of 1997, the NEPA analysis for the Categorical Exclusion 

was finished that summer and a decision memo was written 

and mailed in mid September of that year. The cutting treatments were implemented in the summer of 1998 and 1999. 

District personnel successfully obtained funding (over 

$30,000) for this project from a number of sources including the Nez Perce Tribe, Rocky Mountain Elk Foundation, 

National Fish and Wildlife Foundation, U.S. Forest Service 

Research, and Hazardous fuels.

The District implemented a fuel enhancement treatment by cutting any subalpine fir or Engelmann spruce tree 

that could be used to increase fuel loadings and improve 

continuity of the fuelbed. They directionally felled these 

trees to fill in bare soil gaps within the fuelbed, but, in 

many parts of the stand, there were insufficient subalpine 

fir trees to optimally augment the fuelbed. The District fire 

crew did some of the saw work but most was accomplished 

through an experienced contract crew. The cutting was done 

in September 1998. The District estimated that they spent 

around $20 to $40 per acre for slashing this unit.

This unit was burned in September 12, 2002, by Powell 

Ranger District fire crews using strip headfires with strips 

varying from 10 to 60 ft wide. Fuels were mostly dry with 

fine material around 10 to 15 percent (1 hr = 10 percent, 

10 hr = 14 percent, 100 hr = 14 percent), coarse woody 

debris (1000 hr) around 20 percent for sound logs and 19 

percent for rotten logs, and live fuels at around 100 to 160 

percent (154 percent for herbs and 100 percent for shrubs). 

Weather conditions at the time of the fire were sunny, warm 

(60 to 70 °F), with 5 to 10 mph winds and relative humidity 

Figure 4.20. An example of a stand-level 

restoration activity implemented in a 

whitebark pine stand on Beaver Ridge of 

the Clearwater National Forest, Idaho. 

(a) location of the five stands in the 

Keane and Parsons (2010b) study with 

Beaver Ridge location shown, and (b) the 

Beaver Ridge study stands with the stand 

discussed as Unit 5A.

(a)

(b)
80 USDA Forest Service RMRS-GTR-279. 2012.

around 30 percent. Weather preceding the burn was typical 

fall conditions with cool days and cold nights.

This prescribed burn was originally designed to mimic a 

stand-replacement fire using a high-intensity prescription, 

but logistical concerns and insufficient fuels, even with the 

fuel enhancement cuttings, demanded a less intense fire. 

Thus, the district implemented a mixed severity burn at the 

high end of the mixed-severity category. Flame lengths on 

this unit were variable from 1 to 10 ft high with passive 

crown fire behavior observed throughout the burn. Many 

trees were killed by the fire but in very patchy distributions, 

especially above the road near the ridgeline. Many subalpine fir trees crowned during the fire but there were large 

patches of 100-year old lodgepole pine that did not crown 

and many survived the prescribed burn. The fire was primarily carried through the shrub (Vaccinium spp.) and herb 

(Xerophyllum tenax, for example) fuelbeds so flame lengths 

were often low and creeping in lodgepole pine patches. 

This burn met nearly all burn plan prescriptions but the 

tree mortality was highly variable. The burn was extensive 

and covered most of the unit (greater than 60 percent) and 

consumed many fine fuels. The prescribed burning was estimated at $600 per ha for 40+ ha. Unfortunately, the burn 

severity patterns inside the research plots were somewhat 

different than the severity distribution outside the plots.

The combination of cutting and burning were successful in removing many subalpine fir and spruce trees, but 

the low level of fuel augmentation coupled with the moist 

burning conditions did not allow the fire to achieve burn 

severities to mimic stand-replacement or high intensity 

mixed severity fire. Keane and Parsons (2010a) suggested 

burning when fuels are drier and relative humidity is lower. The chances of accomplishing a prescribed crown fire 

might be low in this forest type and mixed severity burns 

might be the conservative choice. Again, whitebark pine 

tree regeneration was marginal on this site, which could 

be a result of high whitebark pine mortality on this isolated ridge resulting in little nutcracker caching. Keane and 

Parsons (2010a) recommended that burned areas with high 

levels of blister rust mortality be planted with whitebark 

pine seeds or seedlings to ensure future dominance of this 

species. The collection of the seed from phenotypic rustresistant whitebark pine trees will increase the chance that 

the planted stock or seed will survive the exotic disease 

infection. Keane and Parsons (2010a) suggested that an 

evaluation of the success of natural regeneration must be 

made at least a decade or two after burning.

Tree Scale

The finest scale included in this strategy is the tree level 

where treatments are designed for individual trees. These 

trees can be any size and age but they are usually coneproducing mature whitebark pine or vigorous advanced 

whitebark pine regeneration (tree planting was covered at 

the stand scale). Again, planning and prioritization analyses 

are rarely conducted at this scale because the factors that 

control tree dynamics are manifest at broader scales. In this 

report, we describe the tree from a set of measurable characteristics, such as species, diameter at breast height, height, 

crown base height, and, of course, rust infection level.

Assessments

There are few assessments that need to be made at the 

tree scale to promote whitebark pine restoration efforts. 

Perhaps the most common assessment is the identification 

of individual trees that are the most valuable to sustaining viable, rust-resistant whitebark pine populations. 

These trees are most often mature, cone-producing whitebark pine trees that outwardly show signs of blister rust 

resistance (Mahalovich and Dickerson 2004). The primary 

sign would be a healthy tree with no blister rust flagging or 

blisters in a stand where most other whitebark pine trees 

have been killed by the rust (Hoff 1992) (Figure 4.21), with 

30 percent or more live green crown. Since blister rust resistance is positively correlated with growth (Mahalovich 

2012; Mahalovich and others 2006), dominant and codominant specimens should be favored (Mahalovich, 

personal communication). Area surveys for blister rust 

and mountain pine beetle incidence and for plus tree designations indicate that whitebark pine exhibits a negative 

relationship between blister rust resistance and mountain 

pine beetle tolerance. During moderate rust infestations 

(50 to 90 percent mortality levels), specimens with few to 

no beetle attacks may possess desirable genes for insect 

tolerance. These trees are extremely valuable and it is suggested that efforts be made to protect these surviving relics 

from beetles, rust, and competing conifers. In particular, 

cone-bearing plus trees in the rust resistance breeding 

program must be kept alive until their offspring are evaluated for rust resistance. Those plus trees whose progeny 

exhibit resistance will be extremely important for future 

cone collections and scion material for grafting and use in 

rust-resistant seed orchards. Identification and mapping of 

the location of individual high value whitebark pine trees 

is important for planning. Tree location information should 

be used when making resource management decisions such 

as fire use planning.

Other assessments might be to identify individual subalpine fir, spruce, or mountain hemlock trees that pose the 

greatest threat to whitebark pine survival. These trees might 

be out-competing whitebark pine trees for light, water, or 

nutrients, or they could be providing heavy, adjacent canopy and surface fuels that could foster lethal wildland fire 

and contribute to killing healthy, cone-bearing whitebark 

pine. This is especially important in the whitebark pine 

community types where many mature whitebark pine trees 

are surrounded by a “skirt” of subalpine fir regeneration 

(Arno and Weaver 1990). Prioritizing mature stands with 

high rust mortality containing healthy, apparently rust-resistant cone-bearing trees is very important in assessing the 

potential of an area to regenerate to viable whitebark pine 

communities.
USDA Forest Service RMRS-GTR-279. 2012. 81

Figure 4.21. Mature, cone-producing whitebark pine tree with apparent blister rust resistance because it is surrounded by dead 

or dying whitebark pine.

Restoration Actions

Probably the most common tree-level restoration activity 

is the protection of trees from disturbance agents, primarily 

fire, beetles, and rust. The best trees to protect from these 

agents are those that have been identified as important 

sources for phenotypic rust-resistant seeds (“plus” trees) 

(Mahalovich and Dickerson 2004). Protection of trees from 

damage from wildland fire (prescribed, CW, or wildfire) 

is difficult and costly, and yet often successful (Keane and 

Parsons 2010a; Murray 2007c). Mechanical manipulation 

of fuel surrounding the trees by (1) raking or blowing (via 

leaf blower) litter and duff away from tree bases, (2) cutting 

competing fir and spruce, or (3) manual removal of downed 

woody, shrub, and herbaceous fuels has been attempted with 

mixed success (Keane and Parsons 2010b) (Figure 4.15). Fire 

crews have wrapped large whitebark pine with fire shelters to 

protect against fire mortality with limited success (Keane and 

Parsons 2010b). Modification of ignition patterns by controlling burn severity using head fires ignited in thin strips may 

be the most successful way to minimize whitebark pine firecaused mortality in prescribed burning or back-burning in 

wildfires.

Cone collection also occurs at the individual-tree level 

(Halstrom 1995; Mahalovich and Dickerson 2004). Acquiring 

cones can serve several purposes. First, collected seeds can 

be sown in a nursery to produce seedlings for planting in 

recently burned areas or restoration projects (Keane and 

Parsons 2010a). In a wind-pollinated outcrossed breeding 

system, bulked collections should contain a minimum of 20 

cone-bearing trees separated by 60 m (200 ft) in distance 

(Mahalovich and Dickerson 2004). Additional seeds can be 

stored for future operational use in planting whitebark pine 

seedlings. Acquisition of cones is also required for blister 

rust screening procedures (Mahalovich and Dickerson 2004). 

Genetic studies often depend on collected seeds for analysis. Furthermore, seeds are needed for rootstock production 

for seed orchard establishment. As whitebark pine declines 

in distribution, seeds should increasingly be collected and 

stored for ex situ conservation and long-term gene-banking.

Cone collecting can be challenging due to the remote and 

rugged character of whitebark pine habitat and the technical difficulties involved in saving cones from marauding 

animals, especially Clark’s nutcrackers and red squirrels. 

Based on field experiences, guidelines are available that 

can ensure successful collections (Murray 2007b; Ward and 

others 2006b). A basic procedure consists of several steps. 

The first step is stand and tree selection. Criteria used in this 

step may vary depending on purpose (rust screening versus 

long-term seed banking). Once trees are selected, the best 

method to access the cones must be determined usually by 

climbing, but orchard ladders, sectional ladders, and custommade tree-tongs have proven advantageous at some locations 

(Davies and Murray 2006). These cones must be protected 
82 USDA Forest Service RMRS-GTR-279. 2012.

from animal harvest by installing protective devices (stout 

hardware cloth or fine wire mesh cages) in the early summer 

to prevent animal access to the cones (Figure 4.22). Once 

cones ripen in late summer, the cages are removed and cones 

collected. Other techniques for cone harvest might include 

pruning, shooting, and mechanized lifts (Burr and others 

2001) (Figure 4.23). Helicopters have been employed for 

cone harvesting in British Columbia. Cones should be stored 

in a dry, cool, and well-ventilated environment while awaiting seed extraction.

Another tree-level restoration action is pruning rust-infected branches to delay or prevent rust infection and mortality 

(Burns and others 2007, 2008). This involves cutting off the 

branches that have signs of rust infections at the bole to prevent rust infection of the main trunk. While this method can 

delay rust mortality, it is not a long-term solution and will 

probably be ineffective as additional branches are infected in 

subsequent years.

Management Concerns

All whitebark pine trees greater than 20 cm (8 inches) 

DBH (Diameter Breast Height) are susceptible to mountain 

pine beetle, but recent research has found that the beetle can 

successfully reproduce in whitebark pine as small as 10 cm 

(4 inches) DBH (Logan and Powell 2001; Logan and others 

2003). Changing the microsite conditions around a tree by 

removing competing trees can also cause stress and make 

the trees more susceptible to mountain pine beetle attack 

in the short-term (Baker and Six 2001). Managers should 

strongly consider protecting valuable rust-resistant trees 

from mountain pine beetle. Carbaryl is the most effective 

pesticide treatment, especially when beetles are at epidemic 

levels. Carbaryl has shown to provide greater than 90 percent protection for two years (Gibson and Bennett 1985). 

The anti-aggregation pheromone Verbenone is also currently 

Figure 4.23. Collecting cones 

in whitebark pine trees 

(Photo courtesy of Michael 

Murray).

Figure 4.22. Installing cone 

cages on whitebark 

pine near an on-looking 

nutcracker.
USDA Forest Service RMRS-GTR-279. 2012. 83

being used to protect whitebark pine trees during beetle epidemics (Bentz and others 2005; Kegley and Gibson 2004).

Even when mountain pine beetle populations are at endemic levels, managers should consider using Verbenone 

or spraying Carbaryl on high value trees within the stands 

where restoration treatments are implemented (Baker and 

Six 2001). Since mountain pine beetle populations can build 

in stressed trees in treatment areas and spread to other areas, managers should consider treating high value trees in 

adjacent stands as well. When mountain pine beetle is at epidemic levels, widespread mortality is likely. In mechanical 

or prescribed burn treatment areas, using Carbaryl on high 

value trees within or nearby the stand during epidemic situations is strongly recommended. Carbaryl provides two years 

of effective protection and is the best way to protect trees 

from mountain pine beetle. Application can be difficult because the solution must be sprayed on the tree bole to a point 

of runoff (approximately 4 to 5 gallons of solution per tree) 

up until the bole is 5 inches in diameter or less.

Verbenone is purchased in plastic pouches that are easily 

tacked on the tree. It is much easier to apply, but the level 

of protection is significantly lower than Carbaryl. Current 

studies are working to improve Verbenone’s effectiveness. 

Bubble pouches containing the pheromone are placed on the 

tree prior to mountain pine beetle flight (usually late June 

through September). Verbenone is not as effective when 

beetles are at epidemic levels. Current studies are assessing 

the effectiveness of Verbonone when combined with other 

measures such as pheromone baited funnel traps. For more 

information on the use of Carbaryl and Verbenone, managers should contact a local State and Private Forestry, Forest 

Health Protection/Monitoring representative.

Collecting cones by climbing the tree may be damaging 

to the tree. Wounding from climbing spikes or chain steps 

may facilitate mountain pine beetle attack. These wounds 

could be entry avenues for pathogens and may attract wildlife gnawing (porcupines and squirrels, for example). Care 

should also be taken when cutting subalpine fir or removing 

surface fuels around valuable cone collection trees to avoid 

wounding.

Example

The activities employed in the Keane and Parsons (2010b) 

study provides comprehensive examples of the protection 

of high quality rust-resistant trees. Historic blazed trees at 

the Blackbird Mountain study site were protected using fire 

shelters because they were deemed archeological relics. This 

protection yielded mixed results with about half the blazed 

trees damaged by the prescribed burn. Surface fuels were 

removed from the base of some trees at the Smith Creek and 

Bear Overlook site using hand piling and raking. Verbenone 

patches were placed on mature whitebark pine trees on the 

Smith Creek site from 1998-2000 to protect against possible 

endemic mountain pine beetle attacks. At the Beaver ridge 

site, subalpine regeneration “skirts” around large whitebark 

pine trees were manually cut and piled, and several healthy, 

cone-producing whitebark pine trees in the control unit were 

selected as plus-trees; cones were harvested from these trees 

for three years.

To help abate the loss of trees due to blister rust disease, 

Crater Lake National Park collected cones for resistance 

testing from portions of the Park with the highest degree 

of blister rust incidence. Mature trees with no cankers were 

selected as disease-resistant candidates. The particular 

technique used to cage and collect depended on each tree’s 

physical traits and proximity to a road. Climbing, orchard 

ladders, and tree tongs were employed. Wire-mesh cages 

(0.2 to 0.5 mm) were installed in early summer. Retrieval 

and cone collection in late September and early October 

yielded about 265 cones from 88 cages. By late October, all 

cones were delivered to the Dorena Genetic Resource Center 

for formal rust resistance testing. Each collecting technique 

had distinct strengths and weaknesses that are detailed in 

Murray (2007a, 2007b).
84 USDA Forest Service RMRS-GTR-279. 2012.
USDA Forest Service RMRS-GTR-279. 2012. 85

In this report, we present various methods, data, and 

models that could be used to implement a viable range-wide 

restoration strategy, and at the coarsest scale (the species 

range) we have presented a strategy for prioritizing whitebark pine regions. However, the implementation of the 

strategy at finer scales depends on many biological, abiotic, 

political, and societal factors that occur across all scales of 

organization and space. The available resources ultimately 

govern any restoration effort, and this includes not only 

funding, but also the number of trained resource professionals, experienced managers, and knowledgeable decision 

makers that can engage in restoration planning and implementation. Experience in prescribed burning and restoration 

treatments in whitebark pine systems, for example, is not as 

common as experience in burning other ecosystems.

One of the greatest challenges in designing restoration 

projects at any scale is the clear articulation of project objectives to comprehensively inform the prioritization, design, 

and implementation of that project. While seemingly obvious, this is easily the least understood concept in conducting 

restoration activities. Without an explicit statement of objectives, it is problematic, and perhaps impossible, to plan 

and implement a restoration project that can be evaluated 

for effectiveness and success. A clear objective makes key 

restoration analyses and decisions easy, such as (1) prioritization criteria, (2) variables to measure and monitor, (3) 

treatment design criteria, (4) appropriate spatial and temporal scales, and (5) future research. The restoration objective 

would provide the foundation for building a comprehensive 

restoration plan.

Planning and prioritizing regions, landscapes, and stands 

in this strategy demands a comprehensive technique to rank 

the factors being prioritized in an objective, consistent, and 

efficient manner. Prioritization matrix approaches are the 

simplest to implement at any scale of analysis. The selected 

factors for assessment are assigned a relative importance for 

each item being prioritized (stands, landscapes for example) 

based on management objectives, available resources, and 

critical issues of the day (Jenkins 2005). Keane and Arno 

(2000) present a comprehensive multiple scale method of 

deciding where restoration activities should be implemented 

and what type of treatment is the best based on disturbance 

regimes, primarily wildland fire.

Decision Support Systems

There is a wide array of decision tools to aid in the prioritization of areas for restoration (Reynolds and Hessburg 

2005). Hessburg and others (2007) used a logic model 

called EMDS to prioritize watersheds for fuel treatments in 

the central Rocky Mountains. They summarized fine-scale 

spatial data (30-m pixel resolution) up to a coarse-scale 

analysis unit (6th code HUC watersheds) and then assigned 

a rating system using fuzzy logic to rate watersheds according to hazard and risk. A similar analysis was completed by 

the Northern Region of the U.S. Forest Service for whitebark pine (see “Region Scale” section). Cipollini and others 

(2005) presented an expert opinion based decision analysis 

technique for prioritizing prairie openings for restoration. 

Any of these tools provide the platform that would evaluate selected factors with a minimum of subjectivity and 

inconsistency.

5. Implementation of Restoration Strategy
86 USDA Forest Service RMRS-GTR-279. 2012.
USDA Forest Service RMRS-GTR-279. 2012. 87

While this strategy provides critical information for planning and implementing whitebark pine restoration efforts at 

multiple scales, its success lies in the ability of managers 

to tailor restoration designs to local conditions. In nature, 

it is impossible to design a strategy that will work everywhere with the same level of effectiveness. It is left up to 

the manager to craft a restoration plan that will be successful for a specific area by addressing critical local conditions 

such as rust infection levels, mountain pine beetle mortality, 

fuel loadings, successional status, HRV, public issues, and 

whitebark pine mortality. Hopefully this range-wide strategy 

provides helpful direction on how to design restoration projects and details those efforts that need to be accomplished at 

the appropriate scale.

The success of future whitebark pine restoration efforts 

will be greatly dependent on the lessons learned in previous attempts (Keane and Parsons 2010b). Everyone will 

benefit by the detailed documentation of the successes and 

failures of all restoration efforts (Logan and others 2008). 

Therefore, monitoring restoration treatments is required for 

providing the critical information needed to fine tune this 

restoration strategy to local areas. The first need for monitoring is a system of protocols, databases, and sampling 

methods for implementing a monitoring project. Several 

monitoring systems are available, including FIREMON 

(Lutes and others 2006), the FIREMON-FEAT Integration 

(Lutes and others 2009), the U.S. Forest Service’s FSVEG, 

and the National Park Service’s Fire Monitoring Handbook 

(USDI 2001). Another need is the collation of all monitoring data into one database for analysis (WLIS, for example, 

Lockman and others 2007). This can be accomplished by 

research and management at various time intervals. These 

data then need to be analyzed at the local, regional, and national scales to document ecosystem responses to restoration 

treatments for modifying restoration designs. Next, results 

from these monitoring efforts should be published so they 

are readily available. Possible publication outlets include research journals, management journals, government reports, 

and the Whitebark Pine Ecosystem Foundation’s newsletter 

Nutcracker Notes. Last, these monitoring efforts need to be 

maintained well into the future because of the long response 

times in whitebark pine ecosystems. There is a role for both 

management and research in whitebark pine restoration monitoring—management could collect the data while research 

could analyze and report the data, for example. However, 

the primary role of research should be to learn more about 

whitebark pine ecology and devise effective restoration approaches so management can adapt their methods to respond 

to these new discoveries.

There is great concern among managers that treating declining whitebark pine ecosystems during a time of 

widespread climate change, rust infections, and mountain 

pine beetle outbreaks might destroy the important remaining whitebark pine seed sources. Allowing lightning fires to 

burn as CWs and proactively lighting prescribed fire might 

kill valuable putatively rust-resistant, cone bearing whitebark 

pine trees. These concerns are valid, but we should consider 

the alternative. Wildfires will happen regardless of our best 

suppression efforts, especially in this high-elevation ecosystem where uncontrolled wildfires would have a greater 

chance of killing valuable rust-resistant individuals than 

managed fires (CW) because they burn under drier, hotter, 

and windier conditions. Even if uncontrolled wildfires don’t 

occur, vegetation succession will, and the result will put an 

even greater competitive stress on the remaining shade-intolerant whitebark pine trees. Seeds from these surviving trees 

would have less chance of being planted in favorable sites 

free of competition because there are fewer burned areas on 

the landscape due to fewer fires. Mountain pine beetle impacts on whitebark pine are devastating, but these impacts 

are no reason to suspend restoration activities. In fact, this 

might be the most important time to initiate restoration actions on the landscape to ensure whitebark pine will continue 

to inhabit high-elevation forests into the future and prevent 

the conversion of sites to subalpine fir. We feel that the key to 

successful restoration in the future is the planting of rust-resistant whitebark pine seedlings after wildland fires, whether 

these fires are controlled, uncontrolled, or prescribed. It is 

also important that the genetic diversity of these seedlings 

is maximized to ensure whitebark pine remains on the landscape as the climate changes. Maintaining a diversity of age 

classes that contain putative rust-resistant whitebark pine is 

critical to sustaining the species over long time periods because it provides the resilience to survive unwanted wildfires 

and the resistance to beetle outbreaks, disease, and climate 

shifts. In the meantime we must concentrate our efforts on 

ensuring the continued presence of whitebark pine on the 

high elevations of Canada and the United States by following 

the strategy presented here.

While the strategy presented in this report may seem complex and complicated because we described it by scale, we 

feel that, in general, it can be summarized by these major 

tasks:

• Collect whitebark pine seed. Gather as much seed as 

possible for genetic testing, gene conservation, rust 

screening, and operational planting.

• Grow rust-resistant whitebark pine seedlings. Cultivate 

as many seedlings as possible to out-plant to disturbed 

areas.

• Let wildfire do the work. Proactive stand-level treatments 

are expensive and time-consuming. Let wildfire treat 

6. Discussion
88 USDA Forest Service RMRS-GTR-279. 2012.

potentially declining areas to reduce competing subalpine 

fir and create caching habitat.

• Save the relics. Save as many putative rust-resistant 

cone-bearing trees as possible for reasons stated above.

• Plant burned areas. Plant all burned areas with rustresistant whitebark pine seedlings. Hopefully, seed 

planting technology can be developed to reduce the cost 

of seedling establishment. Do not depend on nutcracker 

dispersal, especially in areas where whitebark pine 

populations are too low.

• Patch in the holes. Use stand-level treatments to restore 

high value or critical declining stands, especially those 

stands that are distant from seed sources, that contain 

putative rust-resistant cone-bearing trees, or that are 

too valuable to lose from uncontrolled wildfire (critical 

grizzly bear habitat, for example).

• Measure then measure again. Inventory and monitoring 

are critical tasks that need to be implemented so that 

we can evaluate if treatments are successful and adjust 

treatments to improve efficacy.

Future Research

There are many unanswered questions concerning the 

management and ecology of whitebark pine, and critical 

research is needed in many areas to improve the success 

and efficiency of restoration treatments. These research efforts need to be well organized, encompass more than one 

scale, and include more than one geographic area. Schwandt 

(2006) posed several questions that illustrate our research 

needs:

• What are the frequency, genetic basis, and geographical 

distribution for blister rust resistance?

• How do we define and model factors that affect rust 

infection?

• What is the role of nutcrackers in declining stands?

• How can we reduce mountain pine beetle impacts?

We would like to add the following high priority topics 

for guiding future research in whitebark pine restoration 

(Aubry and others 2008a; Keane and Parsons 2010b):

• Regeneration dynamics: How do we shorten the 

regeneration lag time for high-elevation ecosystems? 

Are there more cost-efficient methods of regenerating 

declining whitebark pine stands than planting seedlings? 

Will planting seeds work? How long must you wait to 

evaluate the success of restoration treatments? Should 

we plant seedlings in a cluster or as individuals? What 

are the roles of microsites in seedling survival and 

success?

• Species autecology: What are life history attributes 

of whitebark pine throughout its range? What are the 

species ecophysiological characteristics (stomatal 

conductance, light compensation point, specific leaf 

area for examples) so that models can be built that 

mechanistically simulate this species? How long does 

it take for regeneration to become established in burned 

whitebark pine stands?

• Cone production: Do restoration treatments actually 

increase whitebark pine cone production? What level of 

cone production is needed to sustain whitebark pine on a 

landscape? How do we determine which stands to plant 

and which stands to allow for natural regeneration? How 

can we efficiently count and collect cones?

• Nutcracker interactions: At what level of cone 

production do nutcrackers become seed predators rather 

than dispersal vectors? Where do most of the seeds 

come from to regenerate large burned areas to whitebark 

pine? What is the interaction between squirrels and 

nutcrackers?

• Blister rust resistance: How can we best evaluate the 

level of rust resistance in individual whitebark pine? 

What level of rust resistance in a whitebark pine 

population is needed to sustain that population into 

the future? How can we accelerate rust resistance in 

whitebark pine?

• Restoration techniques: What are novel restoration 

techniques that are effective and economically feasible? 

What role does prescribed fire, either as wildland fire 

use or management ignited burns, play in whitebark 

pine restoration? What monitoring techniques are best 

for evaluating the success of restoration activities? What 

techniques minimize rust-beetle-climate change impacts 

while still retaining seed-producing, rust-resistant 

individuals on the landscape?

• Fire management: How is fuel best managed in 

whitebark pine restoration plans? How often are 

prescribed burns needed and what areas are best restored 

using prescribed fire, wildfire, and wildland fire use?

• Climate change: What is the influence of changing 

climates on life cycles of blister rust, cone and seed 

insects, mountain pine beetle, and any other exotic 

insect, disease, or plant invader? How will it affect fire? 

How will it affect whitebark pine ecosystem dynamics? 

How do we structure gene conservation, and planting 

guidelines to correspond to changes in climate?

• Ecosystem modeling: Can we simulate whitebark 

pine ecosystem processes under future climates and 

disturbances? Do we know enough about possible 

influences to create comprehensive models? How can 

these models inform management decisions? How do we 

explore ecological interactions and relationships across 

large time and space scales with landscape modeling?

Researchers and managers should promote extensive 

public education concerning the ecology and decline of 

whitebark pine across North America. Non-governmental 

entities such as The Whitebark Pine Ecosystem Foundation 

(www.whitebarkfound.org) are good resources and often willing partners in any public education efforts. It is 
USDA Forest Service RMRS-GTR-279. 2012. 89

incumbent on resource specialists to tell the story of whitebark pine to facilitate effective and timely restoration efforts.

Restoration Barriers and Challenges

Humans have caused much of whitebark pine’s decline, 

so now it appears that humans will now have to put forth 

great effort to keep from losing this keystone species in 

high-elevation western North American ecosystems. The 

conditions contributing to this pine’s decline took decades 

to develop so we expect that successful restoration will take 

decades and even centuries to accomplish. The first step is 

education. Public education is critically needed so that society will understand the scope and depth of the problem and 

be willing to support restoration. Access to nearby whitebark 

communities may provide important opportunities for public 

education, especially at heavily used recreational facilities, 

such as ski areas and National Parks. Land management 

agencies need to educate their staff on the ecology and management of this unique high-elevation ecosystem. The lack 

of comprehensive research in ecology and restoration is also 

a major barrier to conducting efficient and successful restoration treatments. Few research funds are being spent on this 

ecosystem and there are few scientists that have an extensive 

knowledge of this complex ecosystem. Little is known about 

this intricate ecosystem and it is vital that research provide 

the information needed for the sustainable management of 

whitebark pine ecosystems.

There will also be many challenges in implementing a 

comprehensive restoration program across the range of 

whitebark pine. Since whitebark pine has marginal value as 

timber, there will be fewer Federal funds available to pay for 

large restoration efforts. Many lower elevation ecosystems 

are also declining (for example, western larch, aspen, and 

ponderosa pine) and their economic value is much higher 

than whitebark pine (Ferry and others 1995; Hann 1990). 

The remote setting is also a challenge for restoration activities; the number of restoration options for treating whitebark 

pine stands decreases with decreasing accessibility to declining whitebark pine stands. In the United States, most 

whitebark pine forests are found in wilderness or National 

Parks (Keane 2000) and often in the most remote parts of 

these protected areas. In grizzly bear habitats, managers 

should also be concerned about development of facilities 

near or within the whitebark pine zone. Proximity to roads 

and town sites reduced the probability of bear use by 66 and 

92 percent, respectively (Mattson and Reinhart 1997).

There are also barriers to restoration in society and land 

management policies. The public lack of trust in land management agencies coupled with the inability of diverse 

environmental groups to find “common ground” may limit 

any restoration plan proposed by Government agencies 

(Salwasser and Huff 2001). The fight for funding for the 

restoration efforts may be difficult and short lived as more 

issues become important to the public. Conflicting regulations and laws also pose a significant barrier to whitebark 

pine restoration. Endangered species, such as Canadian lynx, 

may require habitat (subalpine fir sapling stands, for example) that could supersede any whitebark pine restoration. 

The wilderness policies for the Forest Service, as another 

example, prevent planting of rust-resistant whitebark pine 

seedlings. These barriers must be overcome to ensure a successful and long-term program of restoring whitebark pine 

on North American landscapes.

Limitations

The restoration strategy presented here may have limitations that must be considered for its implementation. First, 

this strategy and the examples presented herein are based on 

information, technology, and data that were available during the 5 to 10 years prior to the publication of this report, 

so there may be more current information (see Keane and 

others 2011). The strategy is designed to be improved as (1) 

new restoration technologies are developed, (2) additional 

research is completed, and (3) more data become available. 

This strategy, while comprehensive, is not exclusive, and it is 

incumbent on land management agencies to incorporate new 

technology and information in future analyses. This strategy 

is not intended to be implemented as a one-size-fits-all approach across the range of whitebark pine because of the 

tremendous variation in this ecosystem. The guidelines presented in this document are provided for reference and are 

not designed to be implemented in the same way across the 

range of whitebark pine. This report is meant to guide land 

managers as to which attributes to consider when evaluating the condition of their whitebark pine communities and to 

provide a rationale for active restoration. Managers should 

use this information along with specific management direction established for their National Park or National Forest 

to determine when, where, and if active restoration should 

occur.

Managers must also consider that what is best for whitebark pine in the long term may not be what is best for other 

species in that ecosystem, such as the grizzly bear and lynx, 

especially in the short term. According to Mattson and others (2001), “Insofar as we understand them, the means for 

conserving whitebark and grizzly bears may seem somewhat incompatible.” While bears require large areas free 

from human activities, restoration treatments bring humans 

into the whitebark zone. Grizzly bears may suffer from the 

short-term effects of anything that removes cone-producing 

whitebark pine or reduces the population of squirrels or the 

size of middens. On the other hand, whitebark pine may need 

extensive management for it to remain abundant in the long 

term. These decision guidelines are an attempt to emphasize 

restoration treatments while minimizing negative short-term 

effects on grizzly bears.
90 USDA Forest Service RMRS-GTR-279. 2012.
USDA Forest Service RMRS-GTR-279. 2012. 91

We have the knowledge, skills, and experience to successfully restore whitebark pine forests across the species’ 

entire range, even though blister rust and climate change will 

make this task more difficult and complex. There is concern 

among some scientists and managers that treating declining 

whitebark pine ecosystems during a time when mountain 

pine beetle outbreaks are rampant, extensive blister rust 

infection looms large, and climates are rapidly changing, 

might be a fruitless, counterproductive, and inefficient use 

of restoration funding. However, we feel these factors only 

further highlight the pressing need for immediate action to 

prevent the loss of this species and provide a solid rationale 

for strategic research and management planning for the conservation of this ecosystem. Sustaining ecosystem function 

on these valued upper subalpine landscapes so that they will 

be resistant and resilient to climate change requires that we 

conserve as many parts of this ecosystem as we can. The 

potentially devastating impacts of the combination of white 

pine blister rust, mountain pine beetles, and the unknown 

effects of climate change suggest that the time to restore 

these ecosystems cannot be delayed. Losing whitebark pine 

ecosystems before the full range of climate change impacts 

are manifest could lead to a less resilient forest and dramatic shifts in high-elevation ecosystems of western North 

America.

The successful restoration of whitebark pine ecosystems 

will take from decades to centuries. Two major factors will 

ultimately govern the time it takes: (1) the magnitude of resources available over time to conduct restoration efforts, and 

(2) the commitment of natural resource agencies to conduct 

restoration activities for the long term, most likely for many 

decades. Available resources can be in the form of funding, 

personnel, collaborative planning efforts, or public support. 

The success of this restoration strategy ultimately depends 

on the effective and strategic allocation of resources across 

multiple time and spatial scales. Not all whitebark pine forests need to be restored immediately, but a plan must be in 

place to prioritize those areas in the greatest need for restoration, and to also proactively prepare additional healthy 

ecosystems to be more resilient to the on-going threats. 

Conversely, the dedication of adequate resources targeted at 

restoration does not always ensure a successful restoration 

effort or program. The most successful strategy is one that is: 

(1) implemented across all levels of organization; (2) fully 

integrated in planning, protection, and treatment activities 

across many land management agencies at various scales of 

management; and (3) focused on specific local areas rather 

than implemented at low intensity across the entire species 

range. Thus, restoration efforts for whitebark pine need not 

be implemented across an entire National Forest or National 

Park; the most successful programs will concentrate limited 

restoration resources on high-priority sites where potential 

restoration success is high. As funds become available and 

as results of previous restoration efforts are evaluated, this 

process can be repeated on additional sites with new, revised 

restoration treatments designed from information learned 

from previous treatments. This is why it is critical that all 

treatments and actions be monitored to adapt to unanticipated effects of disturbance, climate change, and ineffective 

treatment prescriptions (Logan and others 2008).

The key to successful whitebark pine restoration is facilitating the increase in rust resistance on the landscape, 

whether through natural selection or planting of rust-resistant pine seedlings after disturbance, and the creation 

of high-elevation landscapes that are resilient to climate 

change. Wildland fires, whether wildfires, CW, or prescribed 

fires, are important disturbances for whitebark pine restoration and important components of management plans 

because they create diverse shifting mosaics of upper subalpine communities. It is also vital that the genetic diversity 

of planted seedlings be maximized while also including rust 

resistance traits to ensure whitebark pine forests remain on 

the landscape as the changes in climate and disturbance alter 

landscape processes. The free flow of genetic material across 

the landscape using bird-assisted seeding along with humanassisted planting may be our best strategy for sustaining 

whitebark pines on the high-elevation landscape.

This document is based on the state-of-knowledge at the 

time of writing. However, ongoing research on whitebark 

pine ecology, seed dispersal, fire dynamics, white pine blister rust resistance, grizzly bear use of whitebark pine seeds, 

mountain pine beetle protection methods, whitebark pine 

planting guidelines, effects of global climate change, and 

successional processes will inform future restoration efforts in an adaptive management strategy. These restoration 

guidelines should be revised as needed when this new information becomes available and as additional issues and items 

for consideration arise.

7. The Range-Wide Perspective
92 USDA Forest Service RMRS-GTR-279. 2012.

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In areas where whitebark pine is a component of upper subalpine forests, it is on the 

edge of its species distribution, or there are only scattered whitebark pine trees, skip 

over the stand evaluation criteria and focus on the individual tree selection criteria. 

When damaging agents are minimal or whitebark pine occurs as scattered trees, units 

are asked to select the best available trees from a broad sample to meet the gene conservation goals for the project. If more than one growth habit occurs on a unit, efforts 

should be made to balance selections among the different forms (for example, erect/one 

main stem, erect/multiple stems, and Krummholz/prostrate).

Whitebark Pine Plus Tree Selection Stand and Individual Tree Criteria

Stand-Level Selection Criteria

• Vigorous and representative of the species.

• Habitat type where whitebark pine normally occurs.

• Within the recognized range of the species.

• Broadly sample the geography and range of elevations throughout the forest. When 

infection levels are low and whitebark pine grows in both mixed (e.g., lodgepole 

pine and subalpine fir) and pure stands, balance the number of selections between 

mixed and pure stands.

• Overall composition has a high proportion of living or dead whitebark pine well 

represented throughout the stand.

• Easily accessible by road or trail, if at all possible.

• Uniformly and heavily infected with blister rust (10 or more cankers per tree on the 

average). Average infection level for the stand is determined by carefully counting 

both live and dead cankers on a representative sample of 100 living or dead 

whitebark pines in the stand.

• Presence/absence of cankers (bole and branch) for the 100-tree survey determines 

overall stand infection level.

• A more detailed tally of the number of main-bole and branch cankers for the 

100-tree survey will provide a stand average (cankers/tree) for the individual tree 

selection criteria below. Count the actual number of main-bole cankers and estimate 

the number of branch cankers in the following categories: 0 = no cankers present, 

1-9 cankers, 10-20, 21-40, 41-75, 76-150, and 150+ cankers. (It is recommended 

that complete bole and branch canker tallies be determined for about three trees 

so that one’s eye can more readily determine estimated branch canker amounts by 

category.)

• The combined total of main-bole cankers and estimated branch cankers is equal to 

the number of cankers per tree. The average number of cankers/tree for the overall 

100-tree survey then yields the stand average. When rust infection is heavy and 

infection is high, allowances are made for the possible presence of difficult to see 

or undetectable cankers.

• Selection of resistant trees in uniform stands with confirmed blister rust mortalities 

of at least 90 percent is preferable.

• In stands with 50-90 percent infection due to blister rust, select individuals with no 

more than five cankers.

Appendix A—Whitebark Pine Tree Improvement Program
108 USDA Forest Service RMRS-GTR-279. 2012.

• If representative sampling of the genetic base within a seed zone is not being met 

in stands with greater than 50 percent infection due to rust, then selections will be 

relaxed to include selections from stands with less than 50 percent infection.

o Not less than 25 years old and from 35 to 100 ft tall so that the stand will:

o Have had 25 years of exposure to blister rust.

o Be of cone bearing age.

o Be producing pollen.

o Be easily and safely climbable.

• Of moderately open stand density so the plus tree will:

o Be easy to examine from the ground.

o Have persistent branches to the ground for climbing ease.

o Have full crowns for better cone bearing potential (30% or more live-green 

crown).

Individual Tree Selection Criteria

Relatively free of blister rust when compared to the infection level in the stand as a 

whole. Allowable infection in the candidate tree is summarized as follows:

Stand average (cankers/tree) Candidate tree limit

10 to 20 No cankers

21 to 40 1 canker

41 to 75 2 cankers

76 to 150 3 cankers

151+ 4 or 5 cankers

The presence or absence of cankers in a potential candidate tree is determined by examining the tree from the ground with binoculars and by climbing the tree and examining 

each individual whorl from bottom to top. (Even in the most heavily infected stands, it 

is possible to find canker-free trees).

• Dominant or co-dominant trees are preferable, but the erect/multiple stems or 

Krummholz growth form categories may lend themselves to intermediate or 

suppressed tree crown class categories.

• Far enough apart to be unrelated; there should be a minimum of 300 ft between 

selected trees.

• Free of other insects (mountain pine beetle) and diseases.

• Have a history or the potential to bear cones.

• Be within 5 to 10 chains from the nearest road or trail, unless intervening vegetation 

is sparse enough that longer lines of sight are possible.

• Select no more than three of the best candidates in any given stand.

• Take care to avoid collections from limber pine, when whitebark and limber pine 

are intermixed on the same forest. The operational cone collection guidelines for 

whitebark pine provide additional information on how to distinguish the two species 

by cone morphology, strobilus color, and pollen catkin color.

• No squirrel cache cone collections for plus tree assignments.

Runty, seriously deformed, diseased, or insect-attacked trees should be avoided, as these 

characteristics are likely inherited and passed on to progeny.

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To learn more about RMRS publications:

www.fs.fed.us/rm/publications

www.treesearch.fs.fed.us