Conservation and Management of 

Whitebark Pine Ecosystems

on Bureau of Land Management Lands in the Western United States

Prepared by:

Dana L. Perkins, Ph.D., Forest Ecologist, Bureau of Land Management, Idaho

Robert E. Means, State Forester, Bureau of Land Management, Wyoming

Alexia C. Cochrane, Vegetation Ecologist, Cochrane Consulting (Bureau of Land Management, Idaho, retired)

August

2016

Technical Reference 6711-1
Suggested citation:

Perkins, D.L., R.E. Means, and A.C. Cochrane. 2016. Conservation and Management of Whitebark Pine Ecosystems on 

Bureau of Land Management Lands in the Western United States. Technical Reference 6711-1. Bureau of Land 

Management, Denver, Colorado.

Publishing Services by the Bureau of Land Management, National Operations Center, Denver, Colorado.

BLM/OC/ST-16/004+6711

Pesticide Precautionary Statement

This publication reports research involving pesticides. It does not contain recommendations for their use, nor does it 

imply that the uses discussed here have been registered. All uses of pesticides must be registered by appropriate state or 

federal agencies, or both, before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife—if they 

are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the 

disposal of surplus pesticides and pesticide containers.
Conservation and Management of 

Whitebark Pine Ecosystems

on Bureau of Land Management Lands in the Western United States

Prepared by:

Dana L. Perkins, Ph.D., Forest Ecologist, Bureau of Land Management, Idaho

Robert E. Means, State Forester, Bureau of Land Management, Wyoming

Alexia C. Cochrane, Vegetation Ecologist, Cochrane Consulting (Bureau of Land Management, Idaho, retired)

Technical Reference 6711-1

August

2016

 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States iii

In Memoriam

Dedicated to Robert E. Means (10/1/1953 – 5/26/2015), whose passion for 

forests and love of learning inspired all who worked with him. He was a man of 

highest integrity with the compassion, wisdom, courage, and understanding to 

do his best, to do the right thing, and to make a difference. He succeeded.
Photo by Michael Sulis [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States v

Acknowledgments

We are grateful to the authors of three important strategies for whitebark pine 

restoration, for much of this reference is reproduced from their documents: “A 

Range-Wide Restoration Strategy for Whitebark Pine (Pinus albicaulis)” (Keane et 

al. 2012), “Whitebark Pine Strategy for the Greater Yellowstone Area” (Greater 

Yellowstone Coordinating Committee - Whitebark Pine Subcommittee 2011), 

and “Whitebark Pine Restoration Strategy for the Pacific Northwest Region 

2009–2013” (Aubry et al. 2008). We are also grateful for reviews and editorial 

suggestions from Christy Cleaver, Bob Keane, Mary Francis Mahalovich, Kelly 

McCloskey, Connie Millar, Anna Schoettle, and Diana Tomback. We also send 

a huge thanks to Brian Weihausen for preparing maps and GIS modeling and 

to Mike DeArmond for his inspiring vision of healthy whitebark pine forests. A 

heartfelt thanks goes to National Operations Center employees Nancy Esworthy 

(editor) and Ethel Coontz (visual information specialist) for their excellent 

suggestions, which greatly improved this publication.

We are especially grateful to Kathy Radigan, senior forester in BLM’s Division of 

Forest, Rangeland, Riparian, and Plant Conservation, Washington Office, who 

retired in January 2016 after 30 years of federal service. Not only did Kathy’s 

support and passion for our public lands lead the national BLM forestry program 

forward, but her vision and guidance inspired and made possible the creation of 

this document as a valuable resource for conserving and managing whitebark 

pine ecosystems.

 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States vii

Contents

Abstract ................................................................................................... xi

Executive Summary ................................................................................xiii

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

Section 1: Ecology.......................................................................................5

Systematics ...............................................................................................5

Distribution ..............................................................................................5

Description ...............................................................................................6

Importance to Wildlife ............................................................................9

Community Characteristics....................................................................10

Range Margin Populations....................................................................11

Fire ..........................................................................................................11

Genetics..................................................................................................12

Section 2: Disturbances and Threats ....................................................13

Overview.................................................................................................13

White Pine Blister Rust ..........................................................................14

Mountain Pine Beetle ............................................................................16

Climate Change......................................................................................19

Extent of Decline....................................................................................20

Section 3: Conservation Actions ...........................................................23

Mapping .................................................................................................24

Inventory ................................................................................................28

Monitoring .............................................................................................29

Gene Conservation.................................................................................30

Cone Collection for Rust Resistance – Plus-Tree Selection...................31

Protection of Seed Sources....................................................................31

Silvicultural Practices..............................................................................32

Prioritization of Stand Treatments........................................................42
viii Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Summary ................................................................................................45

Research and Management Needs .......................................................47

References ..............................................................................................75

Appendixes

Appendix 1: Maps Showing Probability of Occurrence of Whitebark Pine 

on BLM Lands in Eastern Oregon and Western Idaho and in 

Eastern California and Nevada ........................................51

Appendix 2: White Pine Blister Rust Damage Codes for Ranking Severity 

of Infection, and Mountain Pine Beetle Activity Rating for 

Whitebark Pine................................................................53

Appendix 3: Monitoring Report for Health Status of Five-Needle Pines on 

Wyoming BLM Lands (Reprint).........................................55

Appendix 4: Scion and Pine Pollen Collection and Handling.................57

Appendix 5: Whitebark Pine Plus-Trees in Idaho, Montana, 

Oregon, and Wyoming ....................................................61

Appendix 6: Cone Collecting Guidelines..............................................63

Appendix 7: Whitebark and Limber Pine (Five Needle Pine) Management 

Guidelines for Wyoming BLM, August 2011 (Reprint) .......65

List of Figures and Tables

Figures

Figure 1.1: Whitebark pine mortality from a mountain pine beetle 

outbreak in 2005...............................................................1

Figure 1.2: Whitebark pine distribution map .......................................6

Figure 1.3: Multiple age classes of whitebark pine, limber pine, and 

subalpine fir on Commissary Ridge, BLM-Wyoming ...........7

Figure 1.4: Three whitebark pines, each with multiple stems forming a 

tree clump.........................................................................8
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States ix

Figure 1.5: Male pollen cones and a mature, ovoid-shaped whitebark 

pine cone ..........................................................................8

Figure 1.6: Whitebark pine cones stored in a pine squirrel midden on 

the ground ........................................................................9

Figure 1.7: Whitebark pine cones displayed in the top of the tree, an 

adaptation for bird-dispersed pines..................................10

Figure 1.8: Understory plant community on a xeric site .....................10

Figure 1.9: Siberian slippery jack ectomycorrhizal fungi .....................11

Figure 1.10: A low-intensity, nonlethal surface fire burning in a whitebark 

pine forest.......................................................................12

Figure 2.1: Life cycle of white pine blister rust...................................15

Figure 2.2: Symptoms of white pine blister rust caused by Cronartium 

ribicola ............................................................................15

Figure 2.3: A successful mountain pine beetle mass attack characterized 

by pitch tubes and frass...................................................17

Figure 2.4: J-shaped mountain pine galleries and multiple life stages of 

mountain pine beetle ......................................................18

Figure 3.1: Key components of whitebark pine ecosystem dynamics ...23

Figure 3.2: Whitebark pine distribution mapped using a 60% 

probability of occurrence from a bioclimatic model ..........25

Figure 3.3: BLM-Idaho and BLM-Montana whitebark pine occurrence 

map based on a 60% probability threshold from a 

bioclimatic model ............................................................26

Figure 3.4: BLM-Wyoming whitebark pine occurrence map based on a 

60% probability threshold from a bioclimatic model ........27
x Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Figure 3.5: Species composition from 14 stands in central Idaho and 6 

stands in Wyoming..........................................................29

Figure 3.6: Verbenone pouch stapled to whitebark pine to deter 

mountain pine beetles.....................................................32

Figure 3.7: Hardware cloth cages installed to protect whitebark pine 

cones from predation ......................................................33

Figure 3.8: Inspecting embryos for seed maturity ..............................34

Figure 3.9: Four whitebark pine seed zones that cover most of the 

BLM’s whitebark pine populations ...................................35

Figure 3.10: Post-wildfire planting of whitebark pine seedlings in 2013 

at Windy Pass, BLM-Montana..........................................37

Figure 3.11: A draft Stand Density Index for whitebark pine................39

Figure 3.12: BLM Forester Mike DeArmond examining growth release 

of whitebark pine advance regeneration in 2010 .............40

Figure 3.13: Whitebark pine regeneration following a stand-replacing 

wildfire in 1966 on the Salmon-Challis National Forest.....40

Figure 3.14: Prescribed fire used to kill subalpine fir in early spring......41

Tables

Table 1: Estimated acreage of whitebark pine on BLM lands derived 

from Forest Inventory Analysis (USFS-FIA) data (second 

column); and a bioclimatic model (Warwell, Rehfeldt, and 

Crookston 2007), and Atlas of United States Trees

(Little 1971) (third column). ...............................................7

Table 2: Facilities that extract seed, store seed, sow and grow 

seedlings, conduct white pine blister rust research, and/or 

develop seed orchards in the Northwest and intermountain 

regions............................................................................31

Table 3: Stand-level priorities for determining protection or 

restoration actions, adapted from the GYA Strategy.........43
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States xi

Abstract

Whitebark pine (Pinus albicaulis Engelm.), an important component of western 

high-elevation forests, has been declining in both the United States and Canada 

from the combined effects of the exotic disease white pine blister rust (caused 

by the pathogen Cronartium ribicola), mountain pine beetle (Dendroctonus 

ponderosae) outbreaks, altered fire regimes, and climate change. These 

combined threats have led to the recent listing of whitebark pine as a highpriority Candidate Species under the Endangered Species Act. 

This reference presents general guidelines for planning, implementing, and 

evaluating whitebark pine conservation and management activities on lands 

administered by the Bureau of Land Management. It is adapted from three 

important strategies:

•	 “A Range-Wide Restoration Strategy for Whitebark Pine (Pinus albicaulis)” 

(Keane et al. 2012) 

•	 “Whitebark Pine Strategy for the Greater Yellowstone Area” (Greater

Yellowstone Coordinating Committee - Whitebark Pine Subcommittee 2011) 

•	 “Whitebark Pine Restoration Strategy for the Pacific Northwest Region

2009–2013” (Aubry et al. 2008) 

Key Words: Pinus albicaulis, ecosystem conservation, white pine blister rust, 

mountain pine beetle, climate change, high elevation 

August 2016

 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States xiii

Executive Summary

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

western North America because of the combined effects of the exotic pathogen 

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

disease white pine blister rust; mountain pine beetle (Dendroctonus ponderosae) 

outbreaks; altered fire regimes; and effects from climate change. These threats 

have led to the recent listing of whitebark pine as a high-priority Candidate 

Species under the Endangered Species Act (Federal Register 2011). Until the 

status of whitebark pine can be addressed by the U.S. Fish & Wildlife Service, the 

Bureau of Land Management (BLM) is managing it as a special status species, 

guided by BLM Manual 6840, “Special Status Species Management.”

The loss of this high-elevation tree species has serious consequences for subalpine 

ecosystems. Whitebark pine is considered both a keystone species for promoting 

community biodiversity and a foundation species for promoting community 

stability. The large, nutritious seeds are an important food for Clark’s nutcrackers 

(Nucifraga columbiana, which is the primary seed disperser of whitebark pine 

seed) as well as for grizzly bears (Ursus arctos horribilis) and black bears (Ursus 

americanus), and many bird and small mammal species. Whitebark pine is often 

the first conifer to colonize high-elevation sites following ecosystem disturbances 

such as wildfire, and it facilitates establishment of other conifers and vegetation 

by ameliorating harsh environmental conditions, thus acting as a nurse tree. 

Whitebark pines stabilize rocky soils and reduce soil erosion. Their canopies shade 

snowpack, regulating snowmelt and thus regulating downstream runoff. 

Because whitebark pine occurs primarily on national forests or lands administered 

by the National Park Service in “core areas” (i.e., higher elevations), most of the 

existing field research and management has occurred on these lands. The BLM 

manages an estimated 1%–2% of populations in the species’ entire range. This 

is a small but important portion, because the BLM’s whitebark pine populations 

border the major core areas, and also exist on the range margins, in isolated 

stands, and at lower elevations. Areas accessible by roads are being inventoried 

and mapped on BLM lands in Idaho, Montana, and Wyoming. Whitebark pine 

populations have generally not been mapped in California, Nevada, Oregon, and 

Washington, where they occur less frequently. Mapping efforts and inventories 

will be used to prioritize conservation actions using adaptive management 

(discussed in Section 3, Conservation Actions). 
xiv Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

The BLM’s conservation objectives for whitebark pine are: 

1) Protect and maintain the genetic diversity of 

whitebark pine

2) Increase white pine blister rust resistance in future 

whitebark pine populations

3) Document conditions of current and potential 

whitebark pine habitats

4) Protect potential or known rust-resistant seed 

sources

5) Use silvicultural practices, including prescribed fire, 

to restore and maintain populations

This reference details the BLM’s contribution to the 

conservation of whitebark pine, which includes shared 

seed and tree production facilities and shared expertise 

with other federal agencies and private partners. 

Conservation and restoration activities include seed 

collection, protection from mountain pine beetles, use 

of wildland fire, protection of high-value trees from 

fire, density management, and assisted and natural 

regeneration efforts. Research activities include progeny 

testing for rust resistance, cold hardiness, and drought 

tolerance and molecular analysis for genetic structure.

This reference should be used in combination with three 

important strategies: 

•	 “A Range-Wide Restoration Strategy for Whitebark

Pine (Pinus albicaulis)” (Keane et al. 2012). Hereafter 

referred to as “Range-Wide Strategy,” it contains 

detailed autecological and synecological information 

about whitebark pine and range-wide applications of 

guiding principles, and actions for restoration. 

•	 “Whitebark Pine Strategy for the Greater Yellowstone

Area” (Greater Yellowstone Coordinating 

Committee - Whitebark Pine Subcommittee 2011). 

Hereafter referred to as “GYA Strategy,” it includes 

comprehensive action plans of past, current, and 

future restoration actions for the six national forests 

and two national parks that comprise the Greater 

Yellowstone Area.

•	 “Whitebark Pine Restoration Strategy for the Pacific

Northwest Region 2009–2013” (Aubry et al. 2008). 

Hereafter referred to as “PNW Strategy,” it prioritizes 

areas for treatment and identifies current conditions, 

access, and proposed actions in Oregon and 

Washington. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 1

Introduction

Whitebark pine (Pinus albicaulis Engelm.) forests are declining 

throughout their range in western North America because of the 

combined effects of four primary threats. These are 1) the nonnative 

invasive pathogen Cronartium ribicola, which causes the disease white 

pine blister rust in five-needle white pines (e.g., Keane and Arno 

1993; Maloney et al. 2012; Schoettle and Sniezko 2007), 

2) native mountain pine beetle (Dendroctonus ponderosae Hopkins 

[Coleoptera: Curculionidae, Scolytinae]) outbreaks (e.g., Furniss 

and Carolin 1977; Bentz et al. 2010; Keane et al. 2012; Meddens, 

Hicke, and Ferguson 2012) (Figure 1.1), 3) altered fire regimes 

(Keane 2001), and 4) effects of climate change (Romme and Turner 

1991; Schrag, Bunn, and Graumlich 2007; Creeden, Hicke, and 

Buotte 2014; Maloney 2014). These combined threats have led to 

the recent listing of whitebark pine as a Candidate Species under 

Figure 1.1 Whitebark pine mortality from a mountain pine beetle outbreak in 2005. 

BLM-Idaho, Challis Field Office.
2 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

the Endangered Species Act (Federal Register 2011). 

Whitebark pine is found on Bureau of Land Management 

(BLM) lands in California, Idaho, Montana, Nevada, 

Oregon, Washington, and Wyoming. Until the U.S. Fish 

& Wildlife Service (USFWS) makes a final determination 

on whitebark pine, the BLM is managing it as a special 

status species—guided by BLM Manual 6840, “Special 

Status Species Management”—in Idaho, Montana, and 

Wyoming, those states where it occurs most frequently.

Loss of this high-elevation tree species poses serious 

consequences for subalpine ecosystems, both in terms 

of the effects on biodiversity and in losses of valuable 

ecosystem processes and functions (Tomback, Arno, and 

Keane 2001a; Tomback and Achuff 2010). Whitebark 

pine’s large, nutritious seeds are an important food for 

Clark’s nutcrackers (Nucifraga columbiana, the primary 

seed disperser of whitebark pine seed), for grizzly bears 

(Ursus arctos horribilis), and for black bears (Ursus 

americanus), and many bird and small mammal species 

(Tomback 1978, 1982; Hutchins and Lanner 1982; 

Hutchins 1994; Mattson, Kendall, and Reinhart 2001; 

Robbins et al. 2006; Lorenz, Aubry, and Shoal 2008). 

It is often the first pine to colonize cold, windswept, 

high-elevation sites following disturbances such as 

wildfire, and it facilitates establishment of other conifers 

and vegetation by ameliorating harsh environmental 

conditions, thus acting as a nurse tree (Callaway 1998; 

Callaway, Sala, and Keane 1998; Tomback et al. 2014). 

Whitebark pines stabilize rocky soils and reduce soil 

erosion. Their canopies shade snowpack, which helps 

regulate snowmelt and downstream runoff (Farnes 

1990). The loss of whitebark pine can also affect fire 

regimes as well as recreational and aesthetic experiences 

(Keane et al. 2002; McCool and Freimund 2001; 

Tomback and Achuff 2010).

Recent condition assessments and research publications 

have focused on upper subalpine and alpine treeline 

areas of the U.S. Forest Service (USFS) and National Park 

Service (NPS) lands, where whitebark pines primarily occur. 

The ecology, threats, and strategies to restore whitebark 

pine have been documented in peer-reviewed publications 

and in publications by the USFS research stations, 

including “Silvics of Whitebark Pine (Pinus albicaulis)” 

(Arno and Hoff 1989); (Pinus albicaulis) Engelm. (Arno and 

Hoff 1990, in “Whitebark Pine: Silvics of North America”); 

and, more recently, “A Range-Wide Restoration Strategy 

for Whitebark Pine (Pinus albicaulis)” (Keane et al. 2012). 

A comprehensive volume, “Whitebark Pine Communities: 

Ecology and Restoration” (Tomback, Arno, and Keane 

2001b), also reviews and highlights autecological and 

synecological information. 

In the last few years restoration strategies and condition 

assessments have continued to be published for different 

geographic regions of the West. The following are 

essential for BLM resource specialists: 

1) “Whitebark Pine Restoration Strategy for the Pacific 

Northwest Region 2009–2013” (Aubry et al. 2008) 

2) “Options for the Management of White Pine Blister 

Rust in the Rocky Mountain Region” (Burns et al. 

2008)

3) “Mountain Pine Beetle Impacts in High-Elevation 

Five-Needle Pines: Current Trends and Challenges” 

(Gibson et al. 2008) 

4) “The Future of High-Elevation, Five-Needle White 

Pines in Western North America” (Keane et al. 2011)

5) “Management Guide to Ecosystem Restoration 

Treatments: Whitebark Pine Forests of the Northern 

Rocky Mountains, U.S.A.” (Keane and Parsons 

2010b)

6) “A Range-Wide Restoration Strategy for Whitebark 

Pine (Pinus albicaulis)” (Keane et al. 2012)

7) “Whitebark Pine in Peril: A Case for Restoration” 

(Schwandt 2006) 

8) “Land Managers Guide to Whitebark Pine 

Restoration in the Pacific Northwest Region 2009–

2013” (Shoal, Ohlson, and Aubry 2008)

9) “Status of Whitebark Pine in the Greater 

Yellowstone Ecosystem: A Step-Trend Analysis 

Comparing 2004–2007 to 2008–2011” (Shanahan 

et al. 2014)

10) “Whitebark Pine in Washington and Oregon: A 

Synthesis of Current Studies and Historical Data” 

(Ward, Shoal, and Aubry 2006b)

11) “Whitebark Pine Conservation for the Canadian 

Rocky Mountain National Parks” (Wilson and StuartSmith 2002)

12) “Whitebark Pine Strategy for the Greater 

Yellowstone Area” (Greater Yellowstone 

Coordinating Committee - Whitebark Pine 

Subcommittee 2011)
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 3

13) Federal Register 2011; Endangered and threatened 

wildlife and plants; 12-month finding on a petition 

to list Pinus albicaulis as endangered or threatened 

with critical habitat: A proposed rule by the U.S. Fish 

and Wildlife Service on 7/19/2011

Less information is available on the condition of the 

lower treeline systems and isolated mountain ranges that 

occur on BLM-administered lands. These whitebark pine 

communities, hereafter called “range margin” habitats, 

are semi-arid, and often border mountain big sagebrush 

(Artemisia tridentata subsp. vaseyana) and Douglas-fir 

(Pseudotsuga menziesii) community types. They function 

as seed sources between continuous populations in the 

northern and central Rocky Mountains. They also serve 

as a seed source for dispersal between distinct mountain 

ranges. Their locations on both upper and lower treeline 

and in semi-arid climate systems could be affected by 

climate change (Romme and Turner 1991; Bower and 

Aitken 2008; Schrag, Bunn, and Graumlich 2007).

This reference is for BLM land managers and resource 

specialists to use with the 13 references listed above 

for prioritizing, designing, and implementing successful 

whitebark pine conservation and management efforts, 

from individual trees for gene conservation to stand- and 

watershed-level treatments. Conservation includes both 

protection and restoration actions.

The BLM’s conservation objectives for whitebark pine are: 

1) Protect and maintain genetic diversity in whitebark 

pine

2) Increase resistance to white pine blister rust in future 

whitebark pine populations

3) Document conditions of current and potential 

whitebark pine habitats

4) Protect potential or known rust-resistant seed 

sources

5) Use silvicultural practices, including prescribed fire, 

to restore and maintain populations
 Photo provided by the National Park Service, U.S.D.I., Public Domain
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 5

Section 1: Ecology

Systematics

Pines are gymnosperms, classified in the class Pinopsida, order Pinales, 

and division Coniferophyta (U.S. Department of Agriculture, Natural 

Resources Conservation Service 2015). Whitebark pine is further classified 

in the subgenus Strobus, the “white” or “soft” pines technically referred 

to as haploxylon pines for having one rather than two fibrovascular 

bundles per needle. Traditionally, whitebark pine was placed in section 

Strobus and subsection Cembrae (Little and Critchfield 1969; Price, 

Liston, and Strauss 1998). Recent genetic studies have suggested that 

Cembrae pines do not form a genetically distinct (monophyletic) group 

(Gernandt et al. 2005). These authors recommended merging two fiveneedle white pine subsections—Strobi and Cembrae—to form a new 

subsection, Strobus, within a new pine section, Quinquefoliae.

Whitebark pine is one of five species known worldwide as “stone pines” 

(Pinus albicaulis, P. cembra, P. sibirica, P. pumila, and P. koraiensis). They 

differ from all other pines in cone morphology. The cones of the stone 

pines are indehiscent, which means that the scales do not open when 

seeds are ripe, so the seeds are retained. The seeds are removed from 

cones by the three worldwide species of “nutcrackers” (genus Nucifraga) 

(Lanner 1982). The nutcracker–stone pine interactions are regarded as 

coevolved mutualisms, whereby the nutcrackers are the primary seed 

dispersers for the five stone pines (Tomback and Linhart 1990).

Distribution

Whitebark pine, along with several other five-needle white pines (Pinus 

flexilis, P. longaeva, P. aristata, and P. balfouriana), occurs at the highest 

elevations of western tree species (Arno and Hoff 1990; Tomback et al. 

2011). Whitebark pine has the largest and northernmost distribution 

of all five-needle white pines (Tomback and Achuff 2010). At its 

northernmost latitudes in British Columbia (55°N), it occurs at elevations 

as low as 5,500 ft (1,680 m), and ranges to elevations above 10,000 
6 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

ft (3,050 m) in Wyoming (42°N) and up to 12,000 ft 

(3,658 m) in California (36°N). Whitebark pine occurs 

primarily in upper subalpine forests and at treeline in 

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: western 

and eastern. The western coastal batholith and volcanic 

chain sections include the Sierra Nevada and Klamath 

mountains of California and Cascade Mountains of 

California, Oregon, Washington, and British Columbia, 

and also the Olympic Mountains of Washington and 

coastal ranges through the Bulkley Mountains of British 

Columbia. The eastern Rocky Mountain sections range 

from the Wyoming and Wind River ranges of western 

Wyoming, north through the Greater Yellowstone 

Area, Idaho, Montana, and north to about 55 degrees 

latitude in Alberta and British Columbia. Whitebark 

pine also grows in the Great Basin ranges of California, 

in western, northern, and eastern Nevada, and in the 

Blue and Wallowa mountains of northeastern Oregon, 

northeastern Washington, and southern British Columbia 

(Little and Critchfield 1969; Ogilvie 1990). Updated 

information for the range-wide distribution of whitebark 

pine, using a standard scale and minimum size polygon, 

is available on the Whitebark Pine Ecosystem Foundation 

website (http://whitebarkfound.org/?p=772).

Whitebark pine on BLM-administered lands occurs 

primarily in Idaho, Montana, and Wyoming, and to 

a lesser extent in California, Nevada, Oregon, and 

Washington. The BLM’s whitebark pine populations 

are often different than those on USFS and NPS lands 

because they include communities of trees at the lowerelevation range of whitebark pine. These include range 

margin habitats, disjunct populations, and geographically 

distinct mountain islands that serve as valuable seed 

sources for distant populations. Individual trees at lower 

treeline, and at high-elevation sagebrush-whitebark 

pine ecotones (~8,000–9,000 ft, 2,440–2,750m) on all 

federal ownerships may be especially drought resistant, 

and provide potential sources of genetic diversity 

(D.L. Perkins, pers. obs.). Because whitebark pine 

historically has not been a species of commercial 

interest, and comprises a small component of forests, 

the distribution of whitebark pine is largely unmapped 

on BLM lands. Acreage estimates based on USFS Forest 

Inventory and Analysis (FIA) data (http://www.fia.fs.fed.

us/) and bioclimatic envelope models (Warwell, Rehfeldt, 

and Crookston 2007) vary from approximately 47,000 ac 

(USFS FIA) to greater than 145,000 ac (Warwell, Rehfeldt, 

and Crookston 2007; D.L. Perkins and B. Weihausen, 

unpublished data). See Table 1.

Description

Whitebark pine occurs on high-elevation sites 

characterized by rocky, poorly developed soils, cold 

temperatures, and snowy, windswept exposures (Arno 

and Hoff 1989). Whitebark pine occurs in three distinct 

community types: 1) trees that are dominant and selfreplacing over time in climax communities, which are 

open stands on harsh, windswept sites, 2) flagged and 

krummholz (matlike growth) trees, growing either solitarily 

or in dense groups with other species (tree islands) in 

treeline communities, and 3) a minor to major seral species 

Figure 1.2 Whitebark pine distribution map (Arno and Hoff 1989). 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 7

on productive sites with other conifers, such as subalpine 

fir (Abies lasiocarpa), lodgepole pine (Pinus contorta), 

Douglas-fir (Pseudotsuga menziesii), Engelmann spruce 

(Picea engelmannii), limber pine (P. flexilis) (Arno and Hoff 

1990; Tomback, Arno, and Keane 2001b) (Figure 1.3). 

In climax communities, whitebark pine is a long-lived 

tree attaining ages of more than 1,000 years on exposed 

sites. Mature trees older than 400 years are common 

(Luckman, Jozsa, and Murphy 1984; Perkins and Swetnam 

1996). It is slow-growing, investing in extensive root 

systems, and rarely grows faster than 

other conifers except on the most 

severe sites (Arno and Hoff 1990). 

Whitebark pine is considered shadeintolerant to moderately shadetolerant (Minore 1979; Arno and 

Hoff 1990) and a poor competitor, 

which accounts for its successional 

status. On productive sites, it reaches 

heights of 22–65 ft (7–20 m). 

Clark’s nutcracker is the primary 

seed disperser for whitebark 

pine; the birds bury seeds several 

centimeters deep in soil or other 

substrate in caches of 1–15 seeds 

(Tomback 1978; Hutchins and 

Lanner 1982; Lorenz et al. 2011). 

Seeds that are not retrieved from 

these seed caches may germinate 

in place, leading to seedling 

establishment. As a consequence 

of multiple seeds in a cache, 

whitebark pine frequently occurs as 

a “tree cluster,” which is a closely 

associated group of genetically Figure 1.3 Multiple age classes of whitebark pine, limber pine, and subalpine fir on Commissary 

Ridge. BLM-Wyoming, Kemmerer Field Office. 

Table 1. Estimated acreage of whitebark pine on BLM lands derived from Forest Inventory Analysis (USFS-FIA) data (second column); and a bioclimatic 

model (Warwell, Rehfeldt, and Crookston 2007), and Atlas of United States Trees (Little 1971) (third column).

State Forest Inventory 

Analysis acres

Bioclimatic model 

acres (≥60% probability 

of occurrence)

Idaho 24,219 77,993 

Montana 11,827 40,473

Wyoming 11,700 21,142

California Not available 3,359

Nevada Not available 1,894

Oregon Not available 1,465

Washington Not available 32

Total 47,746 146,358

Note: A 60% threshold for probability of occurrence from the bioclimatic model gave the most reliable estimates when verified with field data. 
8 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

distinct stems (Lanner 1980; Linhart and Tomback 1985; 

Furnier et al. 1987) (Figure 1.4). It also occurs as a singlestemmed form. The krummholz form that occurs at 

the highest elevations is long-lived, and reproduces by 

layering (King and Graumlich 1998). It is less common 

than the upright tree form on lower-elevation BLM lands. 

Whitebark pine seeds may be cached near source trees 

or more rarely transported 20 mi (32 km) or farther 

across the landscape (Lorenz et al. 2011; Tomback 1978). 

Nutcrackers cache across a variety of terrain, primarily in 

their home areas, which range in size from 0.5 to 20 sq 

mi (1.4–52 sq km). They use many forest types, including 

ponderosa pine (Pinus ponderosa), mixed conifer, and 

whitebark pine habitats. Seed caches are generally close 

to source trees (Lorenz et al. 2011; Tomback 1978), 

but have also been reported in open areas (Norment 

1991) and burned areas (Tomback, Sund, and Hoffman 

1993; Tomback et al. 2001). In contrast with resident 

nutcrackers that have established home ranges, 

nutcrackers also occur as migrant populations, caching 

seeds in autumn and moving on to new locations (Lorenz 

et al. 2011). Because whitebark pine seeds are primarily 

dispersed by Clark’s nutcracker, nutcracker behaviors 

and population dynamics are extremely important to 

whitebark pine conservation. More information on 

nutcracker-pine interactions can be found in the RangeWide Strategy, pages 8–11, and on the interagency 

website (http://ecoshare.info/projects/whitebark-pine/). 

Whitebark pine is a monoecious species, with both male 

and female strobili located on the same tree (Arno and 

Hoff 1990). Female cones (strobili) are deep purple when 

immature, purple-brown when mature, elliptical in shape, 

and grow at the tips of branches, primarily in the upper 

crown (Figure 1.5) (Arno and Hoff 1989). Male pollen 

cones are pink when mature, fading to orange when dry, 

and are generally found in the lower crown (Figure 1.5). 

Needles occur in fascicles of five, are 1.2–2.8 in. (3–7 

cm) long, and a deep-yellow green to dark-green color. 

Unripe cones are resinous and range in length from 2 to 

3.5 in. (5–8 cm); they are sessile, usually occur in clusters 

of two to five, and remain on the tree unless dislodged 

by animals (Arno and Hoff 1989). Cones are ovoid, with 

scales that are thick distally and terminate in a blunt tip. 

Cones contain about 60 large, 0.28–0.43 in. (7–11 mm) 

long, wingless seeds (Forcella and Weaver 1980; Owens, 

Figure 1.5 Kittirat, and Mahalovich 2008; Weaver and Forcella Male pollen cones (strobili) (upper left) and a mature, ovoidshaped whitebark pine cone (lower right). Cones occur on the tips of branches.

Figure 1.4 Three whitebark pines, each with multiple stems forming a tree 

clump. Multiple stems originate from seeds cached by Clark’s nutcracker, the 

dispersal agent for whitebark pine. 

male pollen cones (pink 

fades to orange when dry)

mature female cone 

(dark purple fades 

to brown when dry)
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 9

1986). Tomback (1982) in the eastern Sierra Nevada 

reported a mean of 45 filled seeds per cone, whereas 

Owens, Kittirat, and Mahalovich (2008) and Weaver 

and Forcella (1986) reported 66 and 75 seeds per cone, 

respectively, in the Rocky Mountains. Whitebark pine 

starts producing cones at 30–50 years of age, with 

sufficient canopy volume to have high cone production 

at about 125–250 years of age (Arno and Hoff 1989; 

Krugman and Jenkinson 1974). The frequency of 

synchronous abundant cone crop years, or masting 

events, varies regionally by climate and population level, 

from yearly to every 2–5 years in many areas, although a 

few cones are produced within a stand nearly every year 

(Arno and Hoff 1990; Crone, McIntire, and Brodie 2011; 

Krugman and Jenkinson 1974; Tomback, Arno, and 

Keane 2001b).

Importance to Wildlife 

Whitebark pines seeds are high in 

dietary fat, and numerous wildlife 

species, including the seed dispersal 

agent Clark’s nutcracker, depend 

on them for a nutritious food 

source. Seeds are relatively large 

and contain from 28% (Robbins 

et al. 2006) to 52% fat, 21% 

carbohydrate, and 21% protein by 

weight (Lanner and Gilbert 1994). 

Their size and thick seed coat make 

whitebark pine seeds a high-quality, 

concentrated, and long-lasting food 

source. Pine squirrels (Tamiasciurus 

spp.) also compete for seeds with 

nutcrackers and cache whitebark 

cones in middens. There is little pine 

regeneration from these middens, 

however. (Figure 1.6). Black bears 

and grizzly bears raid middens, and 

black bears also climb trees to harvest 

cones. Granivorous rodents, such as 

chipmunks, and mice, also consume 

seed and pilfer seed caches (Hutchins 

and Lanner 1982; McCaughey and 

Weaver 1990; Tomback and Kendall 2001; Lorenz, 

Aubry, and Shoal 2008). 

The relationship between whitebark pine and Clark’s 

nutcracker is mutualistic, with positive benefits to both 

Figure 1.6 Whitebark pine cones stored in a pine squirrel midden on 

the ground are generally not a source of seed for regeneration. Photo by BlueCanoe (Own work) [CC BY-SA 3.0 (http://creativecommons.org/ licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
10 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

pine and bird (Tomback 1982; Tomback 

and Linhart 1990, Tomback 2001). 

Nutcrackers disperse seeds farther than wind 

disperses other conifer seeds (Tomback, 

Hoffman, and Sund 1990). Morphological 

characteristics that are adapted for the 

mutualistic interaction with the Clark’s 

nutcracker (Lanner 1982, 1996; Tomback 

1982; Tomback and Linhart 1990) include 

an upswept rounded crown where cones are 

displayed on vertically oriented branches to 

birds, and a closed, or indehiscent, cone that 

ensures availability of seed (Lanner 1982; 

Tomback 1978) (Figure 1.7). 

Community Characteristics

The widespread distribution across soil types 

and varied disturbance histories of whitebark 

pine forests have led to diverse understory 

plant communities. In the northern Rocky 

Mountains and interior Pacific Northwest, 

common plant species on BLM land 

include grouse whortleberry (Vaccinium 

scoparium), gooseberry (Ribes spp.), thinleaf 

huckleberry (V. membranaceum), menziesia 

(Menziesia ferruginea), smooth woodrush 

(Luzula glabrata), and common beargrass 

(Xerophyllum tenax). Other species include 

sedges (Carex spp., mostly Ross’ sedge, C. 

rossii) and Geyer’s sedge (C. geyeri), pink 

mountainheath (Phyllodoce empetriformis), 

and broadleaf arnica (Arnica latifolia), 

depending on geographical area, aspect, 

and elevation (Arno and Weaver 1990; 

Campbell 1998; Keane and Parsons 2010b; 

Pfister et al.1977). Some whitebark pine 

forests have few to none of these understory 

species. In semi-arid whitebark pine 

community types, understory species that 

may occur include Idaho fescue (Festuca 

idahoensis), Parry’s rush (Juncus parryi), 

silvery lupine (Lupinus argenteus), silky lupine 

(L. sericeus), singlehead goldenbush 

(Ericameria suffruticosa, syn. shrubby 

goldenweed, Haplopappus suffruticosus), and 

Wheeler’s bluegrass (Poa wheeleri) (Arno and 

Weaver 1990; Aubry et al. 2008; Mancuso 

2013) (Figure 1.8). While seral communities 

Figure 1.8 Understory plant community on a xeric site includes: shrubby goldenweed 

(Ericameria suffruticosa), Idaho fescue (Festuca idahoensis), Wheeler’s bluegrass (Poa 

wheeleri), prickly sandwort (Arenaria aculeata), and Indian paintbrush (Castilleja spp.).

Figure 1.7 Whitebark pine cones are displayed in the top of the tree, an adaptation for 

bird-dispersed pines. The distended throat of the Clark’s nutcracker is full of seed that the 

bird slips into a pouch under its tongue for transport, caching, or eating.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 11

generally have a lower diversity of vascular plants 

(Forcella 1978), high-elevation climax stands of whitebark 

pine may include many unique alpine, subalpine, and 

montane assemblages of understory species, some of 

which are found only 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. 

Below the ground surface, whitebark pine, like other 

forest trees, requires ectomycorrhizal (ECM) fungi, which 

improve survival on poor sites (Read 1998; Mohatt, 

Cripps, and Lavin 2008). ECM fungi are beneficial, 

forming a symbiotic relationship with the roots of trees. 

Siberian slippery jack (Suillus sibiricus) is one fungus that 

associates only with five-needle pines (Figure 1.9). Others 

include S. tomentosus var. discolor, S. subalpinus, and 

Rhizopogon evadens, although they do not grow as well 

in the greenhouse (C.L. Cripps, pers. comm.). Whitebark 

pine seedlings inoculated with ECM in Waterton Lakes 

National Park, Alberta, Canada, showed a 10%–15% 

higher survival rate over those that were not inoculated 

(Lonergan, Cripps, and Smith 2014). Commercial 

Figure 1.9 Whitebark pine, like other pines, requires ectomycorrhizal 

fungi (white nodules – right) for survival in nature. Beneficial fungi such 

as Siberian slippery jack on the whitebark pine seedling (left) form a 

symbiotic relationship with the roots of trees and aid in nutrient and water 

transport. Rust-resistant seedlings must be inoculated with this beneficial 

ectomycorrhizae before out-planting. 

Ectomycorrhizal fungi, 

Siberian slippery jack 

(Suillus sibiricus) on 

whitebark pine seedling roots.

inocula should be avoided because they contain fungi 

that are not specific for five-needle pines, and many 

will not form mycorrhizae with whitebark pine. More 

information on the benefits of ECM fungi, inoculation in 

nurseries, and threats to ECM fungi can be found in the 

Range-Wide Strategy.

Range Margin Populations

Many whitebark pines on BLM lands occur in small, 

isolated disjunct stands on the range margin of the 

species. These populations differ from the more 

continuous populations that occur on USFS and NPS 

lands, hereafter called the “core” range. Differences 

include small population size, isolated stands, generally 

semi-arid sites, different plant community associates, and 

genetic differences (Anderson et al. 2009; Mahalovich 

and Hipkins 2011; Vergeer and Kunin 2012). Depending 

on aerial distance from other whitebark pine populations 

in relation to Clark’s nutcracker seed dispersal flight 

distances, these isolated disjunct stands may be at 

an elevated risk for local extinction after a severe 

disturbance event, because of the possible scarcity 

of replacement seed from offsite sources. Nutcracker 

seed dispersal flight distances average 7.5 mi (12 km) 

(Tomback 1978; Lorenz and Sullivan 2009).

Fire

Fire is a natural component of many whitebark 

pine ecosystems, creating favorable conditions for 

establishing and maintaining whitebark pine dominance, 

but also causing tree mortality. Severe stand-replacing, 

low-severity, and mixed-severity fires all occur in 

whitebark pine stands, depending on drought cycles, 

fuel conditions, landscape burn history, associated 

vegetation, and high-wind events (Arno 1980; Morgan 

et al. 1994; Campbell et al. 2011). Reported mean fire 

return intervals range from 13 years to more than 400 

years (Campbell et al. 2011). 

Large, stand-replacing fires are often colonized by 

whitebark pine because of long-distance seed dispersal 

by Clark’s nutcracker (Tomback, Hoffman, and Sund 

1990; Tomback, Sund, and Hoffman 1993). When fires 

are severe and thus stand-replacing, whitebark pine may 

become dominant if regeneration is initiated by Clark’s 

nutcrackers within a few years after the burn (Tomback, 

Hoffman, and Sund 1990; Tomback, Sund, and Hoffman 

1993). Low- and moderate-intensity fires can reduce 
12 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

competition from conifers, shrubs, and dense grasses, 

thus maintaining whitebark pine (Figure 1.10). In some 

instances, whitebark pine crown architecture probably 

contributes to survival because its upswept limbs and 

high surface-to-crown height present fewer ladder fuels 

to transfer heat from passing surface fires to the crown 

(Larson and Kipfmueller 2010). On the highest rocky sites, 

where whitebark pines are widely spaced, fire frequency 

is low, and fire extent is small, often burning less than an 

acre or only an individual tree (Tomback 1986).

Although fire was historically beneficial for whitebark pine, 

it can also be detrimental. Climate change is believed to be 

driving the current trend toward longer and more intense 

fire seasons in the western United States (Westerling et al. 

2006; Littell et al. 2010). Whitebark pine may now be at a 

point of lowered fire tolerance. Large high-severity fires can 

severely reduce or even eliminate cone-bearing whitebark 

pines across extensive landscapes. With additional losses 

from blister rust and mountain pine beetle, the loss of any 

whitebark pine trees may result in local stand extirpation. 

Subalpine fir and Engelmann spruce, co-dominants 

with whitebark in seral stands and where succession is 

advanced, are highly flammable, and a fire that moves into 

the crowns of these species may be “stand-replacing.” 

If the fire becomes intense and widespread, killing 

most or all cone-bearing whitebark pines within the fire 

perimeter, seeds from unburned stands within nutcracker 

caching range may be available to regenerate whitebark 

pine. If there are no such seed sources, however, natural 

regeneration of whitebark pine will be extremely slow, or 

the species may fail to become reestablished (Keane and 

Parsons 2010b). This is especially critical in the isolated 

disjunct stands on BLM lands. 

Genetics 

A key component of the BLM’s whitebark pine 

conservation and management program is the planting of 

rust-resistant seeds and seedlings for reforestation (Keane 

and Parsons 2010b; Mahalovich and Dickerson 2004; 

Mahalovich, Burr, and Foushee 2006). Understanding the 

genetics of whitebark pine is essential for developing the 

seed transfer guidelines to accomplish this. An individual’s 

genetic makeup, the environment, and the interaction 

of an individual’s genetic makeup with the environment 

determine an individual’s phenotype (outward 

appearance). Phenotypic variation among individuals 

contributes to variation in measurable characteristics 

(quantitative traits) such as growth, survival, and resistance 

to disease and insects. Genetic variation is 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, Ballou, and Briscoe 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. 

Studies on the genetic structure of whitebark pine, blister 

rust resistance, drought tolerance, cold resistance, and 

other traits are being conducted primarily by Canadian and 

USFS geneticists, researchers, and academics. Whitebark 

pine has not been found to have a major gene resistance 

to blister rust, as have sugar pine (Pinus lambertiana) and 

limber pine (Schoettle et al. 2014); instead, its resistance 

is polygenic (that is, several genes are responsible for 

resistance). More information about these studies can be 

found in the Range-Wide Strategy, GYA Strategy, and PNW 

Strategy and peer-reviewed literature. 

The isolated individuals and small populations on BLMadministered lands may represent the best-adapted trees 

for survival in the BLM’s unique, characteristically dry and 

lower-elevation habitats. These trees are important genetic 

resources for future changing climates and landscapes. 

Figure 1.10 A low-intensity, nonlethal 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. The thin bark makes it susceptible to mortality, 

however, when intensities are higher.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 13

Section 2: Disturbances 

and Threats

Overview

The decline of whitebark pine across most of its range in North 

America is the result of multiple, recent human-caused and natural 

events (Arno 1986; Kendall 1995; Kendall and Keane 2001; Tomback, 

Arno, and Keane 2001a; for more recent reviews, see Tomback and 

Achuff 2010 and Tomback et al. 2011). The major threats identified 

by the USFWS in its 12-month finding include white pine blister rust, 

mountain pine beetle, changing fire regimes, and changing climate 

(Federal Register 2011). At the stand level, the scale at which the BLM 

populations usually occur, extirpation from these threats has not yet 

been observed.

The most serious event was the introduction of the exotic fungal 

pathogen Cronartium ribicola to the western United States and 

Canada in the early 1900s. This pathogen causes the disease white 

pine blister rust (Geils, Hummer, and Hunt 2010; McDonald and Hoff 

2001). The disease has been found in all five-needle pine species 

except Great Basin bristlecone pine. The pathogen enters host pines 

as basidiospores through the stomates in the needles. Then the 

spores germinate, and the mycelia grow down into the branches and 

eventually into the stem. Several years after infection, sporulating 

cankers will form, ultimately killing the branch’s or tree’s biomass 

above the canker. The individual may die if it does not possess one of 

several resistance mechanisms (i.e., no needle spots, needle shed, short 

shoot, bark reaction [Hoff 1986; Mahalovich and Hipkins 2011]) or if it 

does not exhibit canker tolerance. 

Mountain pine beetle outbreaks are historically a natural, intermittent 

disturbance event in whitebark pine communities (Ciesla and Furniss 

1975; Furniss and Carolin 1977; Arno and Hoff 1989). Several major, 

natural mountain pine beetle outbreaks during the last 90 years have 
14 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

killed many mature, cone-bearing whitebark pine trees 

across the range (Arno 1986; Perkins and Swetnam 1996; 

Baker, Amman, and Trostle 1971; Waring and Six 2005). 

The most recent mountain pine beetle outbreak, which 

began in the late 1990s to early 2000s, depending on 

location, has achieved widespread geographic extent and 

high levels of mortality. Mountain pine beetles create 

breeding chambers in the sap wood, and introduce blue 

stain fungi, a larval food, which spreads throughout the 

wood. Together these two processes interrupt water 

transport and girdle the tree, causing tree death (Solheim 

and Krokene 1998). 

Changes in wildfire frequency and severity caused by 

changing climate and by ongoing fire exclusion practices 

have affected whitebark pine in several ways (Keane et 

al. 2012). Warmer and drier conditions have resulted in 

severe, stand-replacing fires that can destroy both seral 

and climax whitebark pine stands. In the past, during 

wetter and cooler climates, fires were less frequent 

and resulted in a patchwork mosaic of successional 

stages. Suppression of wildland fire has led to advancing 

succession, resulting in reduced whitebark pine basal 

area as shade-tolerant conifer species increase in size 

and density (Keane, Morgan, and Menakis 1994). Fires 

are more likely to spread and intensify in whitebark pine 

communities during the first few years after mountain 

pine beetle outbreaks, when red needles and fine twigs 

and branches are still on trees or have recently fallen to 

the ground. Seral whitebark pine stands composed of 

mixed conifer species may have the high densities and 

ladder fuels sufficient for intense crown fires. 

Climate change has the potential to affect physiology 

and biochemical pathways (Wikelski and Cooke 2006) 

and phenology (i.e., the timing of recurring life history 

events) (Ovaskainen et al. 2013) and could change the 

frequency, duration, and intensity of disturbance regimes 

that affect whitebark pine and other forest ecosystems 

(Dale et al. 2001; Dale et al. 2010). In addition, warming 

trends will result in earlier snowmelt and changing 

local hydrology, which can lead to drought stress and 

mortality (van Mantgem et al. 2009). Further, changes 

in hydrology have led to more severe and longer fire 

seasons (Westerling et al. 2006). Inherent in climate 

change effects is uncertainty, with both beneficial and 

harmful effects forecast (Keane et al. 2012). 

The cumulative effects and interactions of these four 

change agents—blister rust, mountain pine beetles, 

climate change, and fire—have resulted in a decrease in 

mature whitebark pine, particularly in the more mesic 

parts of its range (Campbell and Antos 2000; Elderd, 

Dushoff, and Dwyer 2008; Keane and Arno 1993; Six and 

Adams 2007). 

In the more xeric regions, such as the Great Basin ranges 

of California and Nevada and some parts of central 

Idaho, interactions of the four change agents are less 

pronounced because blister rust is currently not present, 

or present only at low levels, and mountain pine beetle 

outbreaks have not been extensive (Gibson et al. 2008; 

C.I. Millar, pers. comm.). In central Idaho and some other 

areas of the northern Rocky Mountains, mountain pine 

beetle outbreaks have declined (Perkins, Jorgensen, and 

Rinella 2015). In the following sections, the current threats 

to whitebark pine and the extent of decline across the 

species’ range are described in more detail. 

White Pine Blister Rust

White pine blister rust is an exotic fungal disease of 

five-needle pines (Burns et al. 2007). It was introduced 

to western North America in several occurrences before 

and during 1910 on infected eastern white pine nursery 

stock grown in France and shipped to Vancouver, British 

Columbia (Geils, Hummer, and Hunt 2010). Since then 

it has spread throughout most of the range of all fiveneedle pines in the United States and Canada without, 

however, affecting Great Basin bristlecone pine.

The blister rust fungus Cronartium ribicola has a complex 

life cycle involving five different spore types on the host 

pine and the alternate hosts (Figure 2.1). Blister rust 

cankers on the five-needle white pine hosts produce 

aeciospores, which transmit the disease to the alternate 

hosts. These hosts are most commonly shrubs of the 

genus Ribes, but also may include forbs of the genera 

Pedicularis and Castilleja (McDonald et al. 2006; Geils, 

Hummer, and Hunt 2010). Basidiospores produced by 

the alternate hosts are fragile, short-lived spores that 

infect pines by entering the needle stomata. This stage 

of the life cycle is the most climatically limited, requiring 

moderate temperatures and high humidity for spore 

production and transmission to pines (McDonald 

and Hoff 2001). 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 15

Blister rust outbreaks in 

North America have often 

been characterized by “wave 

years,” i.e., years when 

climate is especially favorable 

for new infections, resulting 

in significant intensification 

and spread (Mielke 1943). For 

successful germination and 

infection to occur, there must 

be 48 hours of 98% relative 

humidity and temperatures not 

less than 50 °F (10 °C) or more 

than 68 °F (20 °C) (McDonald 

and Hoff 2001). 

Basidiospores typically travel a 

short distance by wind—most 

often a few hundred feet—but 

have been known to spread as 

far as 5 mi (8 km). Spores that 

germinate within the needle 

tissue produce hyphae, which 

then grow into the vascular 

system and into the pine stem 

(McDonald and Hoff 2001; 

Geils, Hummer, and Hunt 

2010; and references therein). 

Between 12 and 18 months 

later, a slightly swollen cankered 

area first becomes visible. 

The following information 

is from McDonald and Hoff 

(2001) and Geils, Hummer, and 

Hunt (2010) and references 

therein: Between 2 and 3 

years after initial infection, 

the canker produces pycnia 

and pycniospores. The 

pycniospores produce gametes 

for fertilizing other infections 

and lead to development of 

the aeciospores (Figure 2.2). 

Aecia form in the same location 

on the canker as the pycnia 

in spring after an additional 

Figure 2.1 Life cycle of white pine blister rust. Initial infection site on pine host occurs through stomates in 

the needle (A). The complete cycle proceeds counterclockwise (B–D) to an alternate shrub host (e.g., Ribes spp.) 

(E– H). (Drawing by Vickie Brewster.)

Figure 2.2 Symptoms of white pine blister rust caused by Cronartium ribicola: Orange needles, called 

flagging, the initial site of infection through stomates in needles (upper left); aeciospores on twig (lower left); 

canker on bole, also with aeciospores (right).
16 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

12–14 months. The relatively tough aeciospores are 

wind-disseminated over distances as great as 310 mi 

(500 km) and infect leaves of alternate hosts. Infection 

of the alternate host also occurs under humid conditions. 

Within weeks of infection, uredinia are produced on the 

leaves of alternate hosts. Urediniospores released by the 

uredinia continue to infect alternate hosts throughout 

the summer, increasing the numbers of infected 

alternate hosts. In late summer to early autumn, hairlike 

telial columns emerge from the old uredinial pustules. 

Teliospores germinate in place on these columns and 

produce basidiospores, starting the process over again. 

The entire life cycle requires 3–6 years for completion, 

depending on climate (Boyce 1961). 

There have been many failed attempts to control blister 

rust. Projects attempting to eradicate Ribes spp. from 

1940 to 1960 were largely unsuccessful because the 

shrub can regenerate vegetatively from rhizomes, and its 

seeds reside in a soil seed bank and germinate after fire 

and other disturbances. Aerial applications of antibiotic 

solutions in diesel oil sprayed on whitebark pine to 

combat blister rust were mostly ineffective and costly, 

and potentially destructive to other species (Brown 1969; 

Maloy 1997). Management actions such as pruning 

infected branches and thinning infected western white 

pine may forestall tree mortality from blister rust, but 

prolong the seed production of nonresistant genotypes 

(Fins et al. 2001).

White pine blister rust damages and kills whitebark 

pine trees by girdling branches and trunks (Hoff 1992), 

thereby reducing seed cone production on individual 

trees and across forest stands. For example, in the 

Bitterroot Mountains of western Montana and eastern 

Idaho, whitebark pine cone production was significantly 

lower in stands with higher rust damage (canopy kill and 

tree mortality) compared with stands having lower rust 

damage that were otherwise similar in forest structure, 

composition, slope, and elevation (McKinney and 

Tomback 2007). Thus, blister rust directly constrains the 

ability of individual trees and forest stands to contribute 

propagules, and hence genetic material, to subsequent 

generations. Furthermore, Clark’s nutcrackers are less 

likely to visit stands with lower cone production, thus 

reducing regeneration potential (McKinney, Fiedler, and 

Tomback 2009; Barringer et al. 2012). 

Whitebark pine blister rust resistance trials initiated at 

U.S. Department of Agriculture, Forest Service (USDA/

USFS) forest genetics centers (Rocky Mountain Research 

Station in Fort Collins, Colorado; Coeur d’Alene Nursery 

in Coeur d’Alene, Idaho; Dorena Genetic Resource Center 

in Cottage Grove, Oregon; Forest Service National Forest 

Genetics Laboratory, Pacific Southwest Research Station 

in Placerville, California) have found low to moderate 

levels of natural resistance in some populations, as 

evidenced by the ability of seedlings to survive multiple 

spore inoculations (Bingham, Hoff, and McDonald 1972; 

Mahalovich, Burr, and Foushee 2006; Vogler, DelfinoMix, and Schoettle 2006; Sniezko 2006; Sniezko et al. 

2011). In high rust mortality areas, resistance ranges 

from 33% in a small sample (n=3) (Hoff, Bingham, and 

McDonald 1980) to 47.4% (n=108) (Mahalovich, Burr, 

and Foushee 2006; M.F. Mahalovich, unpublished data) 

in the Inland Northwest, and 26.3% (n=43) on the Pacific 

Coast (Sniezko et al. 2007). The results are preliminary 

and may not be comparable between testing centers with 

different field seed sampling and resistance assessment 

methodologies. 

Generally, seedlings grown from seed collected from 

healthy trees in stands that are heavily infected and 

damaged by blister rust have the highest probability of 

resistance (McDonald and Hoff 2001). This is because 

these stands have been exposed to the rust for longer 

periods of time, and the surviving trees have a higher 

frequency of rust resistance than the original stand. Rustresistant seedlings (those grown from seeds from screened 

parent trees) have the best chance for survival when used 

in restoration plantings and breeding programs in the seed 

zone from which they were collected. 

Mountain Pine Beetle 

Mountain pine beetle, a native cambial-feeding bark 

beetle, has been considered the most damaging insect to 

whitebark and all other pines in western North America 

(Furniss and Carolin 1977). It typically attacks mature, 

reproductive-aged trees, generally greater than 8 in. 

(20 cm) diameter at breast height (dbh) (Perkins and 

Roberts 2003), although pole-size trees with dbh as 

small as 4 in., or 10 cm, may be attacked in outbreak 

conditions (Cole and Amman 1980). Recent outbreaks 

have occurred from northern British Columbia to 

southern Colorado and resulted in the deaths of millions 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 17

of lodgepole, ponderosa, limber, and whitebark pines 

(Gibson et al. 2008). Trees defend themselves from bark 

beetles primarily through resin exudation (Raffa et al. 

2005; Faccoli and Schlyter 2007; Ferrenberg, Kane, and 

Mitton 2014). However, when the beetles reach high 

densities, they can overwhelm this defense with a mass 

attack strategy (Logan and Powell 2001). 

Typically, outbreaks last 8–12 years in individual stands 

before most suitable hosts are depleted and mountain 

pine beetle populations decline (Roe and Amman 1970; 

Cole and Amman 1980; Perkins and Swetnam 1996). 

Cold weather events and natural enemies sometimes 

curtail outbreaks before host populations are depleted 

(Safranyik and Carroll 2006; Bentz et al. 2010). The cool, 

high-elevation environments of whitebark pine have 

historically led to slow, asynchronous mountain pine 

beetle development and adult emergence from trees, 

thereby moderating outbreaks in these systems (Bentz, 

Logan, and Amman 1991; Logan and Bentz 1999; Bentz 

et al. 2014). Although mountain pine beetle epidemics 

have been documented in whitebark pine in the past 

(Ciesla and Furniss 1975; Perkins and Swetnam 1996; 

Perkins and Roberts 2003), tree mortality during the 

current epidemic that began in the early 2000s exceeds 

that of any previously recorded epidemic (Gibson et 

al. 2008). Warmer temperatures, especially warmer 

minimum temperatures—a consequence of climate 

change—are producing conditions that are conducive to 

more severe mountain pine beetle epidemics. 

Mountain pine beetles spend most of their life cycle 

under the tree’s 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 (feeding and breeding activity) 

in the phloem, and introducing a blue stain fungus that 

inhibits water transport and ultimately kills the tree. 

Signs of a mountain pine beetle attack are pitch tubes, 

which occur 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 (Figure 2.3). Pitch tubes are cream to 

dark-red masses of resin mixed with 

phloem boring dust (frass), and are 

approximately 1 cm long. Unsuccessful 

beetle attacks are called “pitch outs,” 

because the tree’s resin response is to 

“pitch out” the beetles as they attempt 

to bore into the inner bark. 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 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 this may take 

2–3 years in some individuals. Size, 

stress, and health of the tree 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 

Figure 2.3 A successful mountain pine beetle mass attack characterized by pitch tubes and frass 

(boring dust from beetle activity). Mass attacks are lethal to host pines.
18 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

chemical defenses (Progar et al. 2014). Beetles develop 

through four stages: egg, larva, pupa, and adult (Figure 

2.4). Adults mate and then lay eggs that hatch into larvae, 

which develop in the phloem of the tree, completing the 

life cycle. Larval growth is aided by the symbiotic fungi 

Grosmannia clavigera and Ophiostoma montium (Six and 

Adams 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, and the fungal hyphae 

are the primary food source for 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 is infested, the 

sapwood discolors to a bluish tint caused by the fungus. 

Adult mountain pine beetle galleries found under the 

bark are J-shaped and vertically aligned with the stem; 

larvae galleries run perpendicular to the adult galleries and 

terminate in pupal chambers (Figure 2.4). Adult galleries 

range in length from 2 to 3 in. (5–7 cm) to more than 

24 in. (60 cm) and are diagnostic of mountain pine 

beetle attack. 

Mountain pine beetle life cycles span 1–2 years, and many 

empirical, laboratory, and modeling research studies have 

sought to understand the cause of this life cycle variability 

(Bentz, Logan, and Amman 1991; Logan and Powell 2001; 

Powell, Logan, and Bentz 1996). Over most of its range, 

the beetle has one generation per year, but at cooler, 

high-elevation areas, including whitebark pine forest, 

each generation typically takes 2 years (Logan and Powell 

2001). Previously, these forests were generally associated 

with lower beetle-caused mortality because the cold 

environment creates unfavorable heat balance for beetle 

development (Amman 1973; Logan and Bentz 1999). Cool 

temperatures retard development, resulting in longer life 

cycles and/or a disruption of the critical timing of summer 

emergence necessary for a coordinated and successful 

mass attack. Although mountain pine beetles have 

mechanisms to survive in subzero temperatures, sustained 

subfreezing temperatures may result in mortality in all life 

stages (Amman and Cole 1983; Bentz et al. 2010). 

Mountain pine beetle outbreaks and resulting tree 

mortality have been an intermittent and natural 

disturbance factor in western 

forests (Amman 1973; Perkins 

and Swetnam 1996). These 

outbreaks influence canopy 

closure, stand structure, 

species composition, forage 

production, wildlife habitat, 

fuel loading, water yields, 

and aesthetics. Following the 

death of the host overstory 

in outbreak conditions, 

advanced regeneration of 

both whitebark pine and its 

competitors (e.g., lodgepole 

pine, subalpine fir) is expected 

to release. Species composition 

plays a critical role at this 

time; if the stand is composed 

of shade-tolerant species, 

these competitors would be 

expected to remain dominant. 

If the stand is a climax 

whitebark pine community, the 

expectation is for whitebark 

pine persistence.

Figure 2.4 J-shaped mountain pine galleries made by adult mountain pine beetles (upper left); an adult 

mountain pine beetle (lower left). Multiple life stages of mountain pine beetle (right), including an adult, callow 

adults (light brown bodies), and larvae stages.

Black beetle = adult 

mountain pine beetle

Black beetles = adults

Light brown beetles =

callow adults

White larvae with little 

brown caps = larvae

Indention in the wood 

where there are larvae = 

pupae chamber
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 19

Climate Change 

The response of whitebark pine to climate change is 

uncertain. Changing temperature and precipitation 

patterns and timing will affect the phenology and 

synecology of whitebark pine and Clark’s nutcracker, 

as well as the frequency, duration, and intensity of 

disturbances, but outcomes are largely unknown. 

A new USFS Rocky Mountain Research Station technical 

report by Robert Keane and others, “Restoring Whitebark 

Pine (Pinus albicaulis) Ecosystems in the Face of Climate 

Change” (in press), covers climate change as it relates to 

whitebark pine restoration. This report should be used 

alongside the Range-Wide Strategy. Tomback and Achuff 

(2010) and references within also summarize different 

climate change scenarios for whitebark and other white 

pine species.

Some of the greatest effects of climate change will be:

•	 Increases in temperature and more frequent drought

•	 Increased wildfires

•	 Changes in insect and disease outbreaks

•	 Altered distribution, synecology, and phenology of

whitebark pine and other conifers

•	 Changes in distribution and abundance of plant and

animal species

•	 Changes in soil water availability

The 2014 National Climate Assessment (NCA) forecasts 

that the climate in areas currently occupied by whitebark 

pine will change significantly by 2040–2060 (Melillo, 

Richmond, and Yohee 2014). In Idaho, Montana, and 

Wyoming, the NCA forecasts temperature increases of 

4.5 °F – 5 °F. Forecasts from climate models from the 

Middle Rockies Rapid Ecoregional Assessment (REA) 

(BLM 2012) and chapter 7 of the Wyoming Basin Rapid 

Ecoregional Assessment (Ray, Liebmann, and Allured 

2015) forecast temperature changes within the same 

range. Global circulation models of temperature are in 

general agreement, showing increasing temperature 

trends over several decades, depending on the CO2

emission scenario. Slightly wetter conditions (2%–9%) 

within the Idaho, Montana, and Wyoming portions of 

whitebark pine’s range are projected by the third NCA 

(chap. 19, Ojima et al. 2014), a National Oceanic and 

Atmospheric Administration assessment (Kunkel et al. 

2013), the Middle Rockies REA (BLM 2012), and the 

Wyoming Basin REA (Ray, Liebmann, and Allured 2015). 

Models indicate that precipitation will increase in the 

winter and decrease in the summer across most of the 

core range of whitebark pine in this three-state region. 

Reductions in rainfall during dry seasons for the next 

thousand years, however, are forecast for some regions, 

even if carbon emissions were to cease completely 

(Solomon et al. 2009).

Many climate change studies consistently project drier 

conditions across the range of whitebark pine. This could 

result in large increases in the annual number, size, and 

intensity of wildfires and the area burned (Westerling et 

al. 2006; Flannigan et al. 2008; Krawchuk et al. 2009; 

Marlon et al. 2009). Modeling by Littell (2011) and 

Means and Littell (2014) forecasts that by 2040, wildland 

fire acreages may increase by 500%–600% within the 

core BLM whitebark pine areas in Idaho, Montana, 

and Wyoming.

Other disturbance agents, such as insect and disease 

outbreaks, will also be affected by climate change. The 

current large-scale mountain pine beetle outbreaks are 

likely a result of warmer winter temperatures, which 

facilitate beetle expansion and population establishment 

in the higher-elevation whitebark pine zones (Bentz et al. 

2010; Logan and Powell 2001). The response of white 

pine blister rust to warmer temperatures is considerably 

more complicated, because the pathogen is also affected 

by humidity and response of the host species to climate 

change (Keane et al. 2015).

Bioclimatic envelope modeling has been used to project 

changes in whitebark pine distributions under different 

climate scenarios (Tomback and Achuff 2010). These 

models use climate data as independent predictor variables 

and biological data as dependent variables to predict 

species range; they have no inputs for seed dispersal, 

disturbance regime, topography, seedling survival, or soils 

and thus serve only as coarse scale assessments. Hamann 

and Wang (2006) predicted a 73% loss in habitat in 

whitebark pine habitat by 2085, but with an offset gain in 

habitat amounting to 76% of the original area. McKenney 

et al. (2007) projected a 42% decrease in whitebark pine’s 

range. These models are generally in agreement with 

other bioclimatic models (including Warwell, Rehfeldt, and 

Crookston 2007; and Schrag, Bunn, and Graumlich 2008) 

that show a decrease in whitebark pine distribution. 
20 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Keane et al. (2015) discuss the uncertainty of climate 

change models and species’ responses. As an example 

of uncertain responses, there could be higher frost 

mortality of whitebark cone crops due to earlier onset of 

the growing season coupled with high daily temperature 

variability. Or, cone crops could be reduced in the future 

because of the high tree stress from drought. Or, because 

whitebark pine is both drought tolerant and cold tolerant, 

changes in climate variability and timing could have 

minimal impact on species reproduction. 

Climate change will also affect the distribution of many 

species across the landscape. Subalpine fir, alpine larch 

(Larix lyallii Parl.), and spruce are moving into subalpine 

meadows as a result of recent sequential warm years, 

which have led to increased high-elevation regeneration 

(Keane et al. 2015). Recent work by Daly, Conklin, and 

Unsworth (2009) suggests that cold air drainages within 

the current range of whitebark pine may become refugia 

in times of changing climatic conditions. (“Refugia” is 

used here to mean areas where environmental conditions 

may favor or enable a species or community of species 

to survive where it might otherwise perish.) Many of the 

BLM’s whitebark pine stands are on the range margins, and 

there is anecdotal evidence of whitebark pine establishing 

in downslope drainages—in effect, refugia—on BLM lands 

(W.C. Hensley, pers. comm.; R.E. Means, pers. comm.). 

Paleoecological data spanning the last 15,000 years from 

the Greater Yellowstone Area describe the response of 

vegetation to past climate variability. They suggest that 

five-needle pines have been surprisingly resilient to high 

summer temperature and fire activity in the past, but 

that these pines may be more vulnerable to projected 

warmer and drier winters (Iglesias, Krause, and Whitlock 

2015). Keane et al. (2015) also report evidence of warmer 

climates in paleoecological records, which indicate that 

whitebark pine was maintained and even increased in 

some parts of its range (Tausch et al. 1993; Whitlock 

and Bartlein 1993). Whitebark pine can grow within a 

broad upper elevation zone in western North America 

and grows best at high elevations, where there is little 

competition from other species (Arno and Hoff 1989). 

In fact, Arno, Reinhardt, and Scott (1993) found that 

before the modern fire suppression era, whitebark pine’s 

elevation range extended more than 500 ft below the 

current lower-elevation limits in the Bitterroot Mountains 

of Montana. In addition, whitebark pine occupies the 

largest range of any five-needle white pine in the western 

United States and Canada, including about 18 degrees of 

latitude and 21 degrees of longitude, indicating tolerance 

to different climates (Tomback and Achuff 2010). 

Other modeling efforts have shown that whitebark pine 

might be maintained on the landscape if the predicted 

increase in large, stand-replacement fires creates large, 

competition-free burned areas (Loehman, Corrow, and 

Keane 2011; Keane et al. 2015). Moreover, whitebark 

pine may be resilient to changing climates in the northern 

Rocky Mountains because of high levels of genetic 

diversity (e.g., Bruederle et al. 2001; Mahalovich and 

Hipkins 2011), moderate to high heritabilities in key 

adaptive traits (M.F. Mahalovich, in press), demonstrated 

blister rust resistance (Hoff, Bingham, and McDonald 

1980; Mahalovich, Burr, and Foushee 2006; Sniezko et 

al. 2007), minimal inbreeding (Bower and Aitken 2008; 

Mahalovich and Hipkins 2011), and generalist adaptive 

strategies (M.F. Mahalovich, in press). 

In summary, although the effects from global climate 

change on whitebark pine are complex and difficult to 

predict, this is no reason not to implement restoration 

projects (Hobbs and Cramer 2008). Keane et al. (2015) 

state that, because of human-caused factors leading to 

whitebark’s decline as well as the uncertain effects of 

climate change, “Active restoration is the only course 

of action for conserving whitebark pine ecosystems.” 

Climate change scenarios can be incorporated into 

adaptive management and used to guide the design, 

approach, and types of conservation activities across 

the range of whitebark pine. The future will develop 

most likely as combinations of scenarios, some of which 

will be novel and unexpected (Millar, Stephenson, and 

Stephens 2007). 

Extent of Decline

Many upper subalpine ecosystems in the western United 

States and Canada are losing whitebark pine. A number 

of assessments, peer-reviewed papers, and technical 

reports have documented this decline (see the RangeWide Strategy, Table 1.1, p. 31). “The USFS 2013–2027 

National Insect and Disease Forest Risk Assessment” 

(Krist et al. 2014) forecasts that the basal area losses for 

whitebark pine will approach 60% during the next 15 

years, primarily as a result of mountain pine beetle and 

white pine blister rust. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 21

In northern Idaho on USFS-administered lands, repeated 

monitoring of natural regeneration in 1995–2012 revealed 

a 4.3% annual increase of white pine blister rust; average 

mortality in 1995 was 12% and increased to 59% in 

2012. After 17 years, only 2.4% of whitebark pine greater 

than 5 in. dbh were not infected by white pine blister 

rust, and only 15% of the trees less than 1 in. dbh were 

not infected. These results indicate that whitebark pine 

in northern Idaho stands is in serious decline, and survival 

of natural regeneration is in jeopardy due to blister rust 

(Schwandt et al. 2013).

The Greater Yellowstone Whitebark Pine Monitoring 

Working Group repeated measurements of permanent 

belt transects from two time steps, or periods: 2004–

2007 and 2008–2011. This work showed a 20% loss 

of whitebark pine from all causes (mountain pine 

beetle, white pine blister rust, fire, and other). Blister 

rust infection transition from canopy to bole occurred 

in 30% of the revisited trees, while overall infection 

rates remained nearly constant at 0.22 for the first 

time period and 0.23 for the latter time period (Greater 

Yellowstone Whitebark Pine Monitoring Working 

Group 2013). 

Forest inventories using standard stand exam and FORVIS 

(Forest Vegetation Information System, National Science 

and Technology Center, Denver, Colorado) methods 

were conducted on 1,800 ac of whitebark pine, mixed 

whitebark and limber pine, and limber pine stands 

inventoried on BLM lands in 2011–2014. Mortality 

ranged from 15% to 52% from the recent (ca. 2000s) 

mountain pine beetle epidemic, and blister rust levels 

ranged from 0% to 43% for stand-level averages. 

The Whitebark and Limber Pine Information System 

(WLIS) database is a compilation of all plot data 

documenting the condition and decline in whitebark 

and limber pine in the Pacific Northwest and Rocky 

Mountains, and has recently been improved and updated. 

WLIS may be queried to document stand-level declines 

and conditions. (See link below.)

http://www.fs.usda.gov/wps/portal/fsinternet/!ut/p/c4/

04_SB8K8xLLM9MSSzPy8xBz9CP0os3gDfxMDT8MwRydLA1cj72DTUE8TAwjQL8h2VAQAMtzFUw!!/

?ss=1101&navtype=BROWSEBYSUBJECT&cid=stelprdb5157913&navid=140000000000000&pnavid=null&position=Not 

 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 23

Section 3: 

Conservation Actions

This section provides direction on how to manage whitebark pine on 

BLM-administered lands. Our goal is to conserve and maintain whitebark 

pine forests and potential habitats experiencing white pine blister rust, 

mountain pine beetle, wildland fire, and a changing climate (Figure 3.1).

The direction provided is consistent with the BLM’s “Assessment, 

Inventory, and Monitoring Strategy: For Integrated Renewable Resources 

Management” (Toevs et al. 2011) and “Adaptive Management: The U.S. 

Department of the Interior Technical Guide” (Williams et al. 2009). The 

components and actions outlined in the following sections adhere to 

assessment, inventory, and monitoring (AIM) elements: 1) standard set of 

Figure 3.1 Feedback diagram from “Restoring Whitebark Pine (Pinus albicaulis) Ecosystems in the 

Face of Climate Change” (Keane et al., in press), which shows the key components of whitebark pine 

ecosystem dynamics. The background shows whitebark pine mortality caused by a mountain pine beetle 

outbreak in 2007 on BLM-managed lands. BLM-Idaho, Challis Field Office. 
24 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

core quantitative indicators and methods, 2) statistically 

valid sampling design, 3) integration with remote sensing, 

4) electronic data capture and management, and 

5) implementation process. The decision to implement 

activities in the face of uncertainty can be adjusted as 

management and research outcomes become understood 

(Williams et al. 2009). This is a working document and 

is intended to be updated as needed. It also follows the 

principles of the Range-Wide, GYA, and PNW strategies, 

including the associated actions to guide the design, 

planning, and implementation of conservation activities 

and to protect existing habitats. 

The BLM’s conservation objectives for whitebark 

pine are: 

1) Protect and maintain the genetic diversity of 

whitebark pine

2) Increase white pine blister rust resistance in future 

whitebark pine populations

3) Document conditions of current and potential 

whitebark pine habitats

4) Protect known or potential rust-resistant seed 

sources

5) Use silvicultural practices, including prescribed fire, 

to restore and maintain populations

Treatments based on current scientific information will 

have the greatest success and will be the most efficient. 

Two annotated bibliographies address whitebark pine 

ecology, research, and management. The following 

source was published in 2008 and is updated annually: 

http://www.fedgycc.org/wp-content/uploads/2015/06/

whitebarkbibilio_dec162008_nb.pdf

Another source of current research is the Whitebark Pine 

Ecosystem Foundation website (www.whitebarkfound.

org) and references within. We recommend that the 

BLM designate a whitebark pine contact person to 

coordinate activities among states, provide technical 

expertise, and act as the liaison with the other agencies 

and nongovernment organizations that are involved in 

whitebark pine management and conservation. 

The actions supporting the above-described 

objectives are:

1) Mapping

2) Inventory

3) Monitoring

4) Gene conservation 

5) Cone (seed) collection for rust-resistance screening 

6) Protection of seed sources and rust-resistant stock

7) Silvicultural practices

a) Cone collection

b) Seed transfer

c) Planting

d) Density management 

e) Prescribed fire

Mapping 

Initial efforts to map whitebark pine population on 

BLM lands have been conducted in Idaho, Montana, 

and Wyoming, and have focused on areas bordering 

USFS areas where the species is most likely to occur. 

As previously mentioned, BLM acreage estimates have 

been based on USFS-FIA data and bioclimatic models 

(Warwell, Rehfeldt, and Crookston 2007), and vary from 

approximately 47,000 ac (USFS-FIA data) to greater than 

145,000 ac (Warwell, Rehfeldt, and Crookston 2007; D.L. 

Perkins and B. Weihausen, unpublished data; Table 1). 

The area occupied by whitebark pine on BLM-administered 

lands was calculated by Perkins and DeArmond (2009) 

using the 80% probability of occurrence threshold from 

the Warwell, Rehfeldt, and Crookston (2007) bioclimatic 

model and the Atlas of United States Trees (Little 1971). 

However, results underestimated the actual area occupied. 

For example, estimates from this map for Wyoming were 

approximately 300 ac, as compared with 10,000 ac 

from aerial mapping (Means, pers. comm.) and 

11,700 ac from FIA analysis. As a new starting point for 

distribution mapping, a 60% probability of occurrence 

has been found to be the most accurate predictor of 

whitebark pine habitats on BLM-managed lands. The new 

map has been evaluated by foresters in Idaho, Montana, 

and Wyoming, and presence data have been confirmed 

(E. Guiberson, W. Hensley, R. Means, pers. comm.) (Figures 

3.2–3.4). We recommend that BLM resource managers 

use these maps to confirm presence and/or to look for 

new populations of whitebark pine. 

We estimate that the BLM manages an estimated 

1%–2% of whitebark pine stands throughout the 

species’ entire range. This is a small but important 

portion, because the BLM’s whitebark pine populations 

often border core areas of the range, and also exist 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 25

Figure 3.2 Whitebark pine distribution mapped using a 60% probability of occurrence from a bioclimatic model. Red polygons depict areas on BLM-administered 

lands where whitebark pine occurs or is likely to occur (Warwell, Rehfeldt, and Crookston 2007).

on the range margins, in isolated stands, and at lower 

elevations. These areas are largely unmapped. 

Approximately 84% of whitebark pine occurs on federal 

land, and 48% occurs in designated and recommended 

Wilderness (Keane 2000). On BLM-administered lands, 

76% of potential and actual whitebark pine habitat is 

in designated Wilderness or Wilderness Study Areas. 

Other areas that may have whitebark pine include BLM 

Areas of Critical Environmental Concern (ACECs) and 

Research Natural Areas (RNAs). These designations 

pose challenges, both legal and philosophical, for 

whitebark pine conservation and management efforts. 

From a practical standpoint, management activities are 

logistically challenging in areas that have no roads and 

where motorized equipment and mechanical transport is 

prohibited. 

BLM field offices are currently inventorying and mapping 

areas accessible by roads in Idaho, western Montana, 

and western Wyoming. This location and accessibility 

information can be used to prioritize conservation and 
26 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Figure 3.3 BLM-Idaho and BLM-Montana whitebark pine occurrence map (red polygons) based on a 60% probability threshold from a bioclimatic model. 

Green polygons represent all lands where whitebark pine occurs at a probability of 60% (Warwell, Rehfeldt, and Crookston 2007).
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 27

Figure 3.4 BLM-Wyoming whitebark pine occurrence map (red polygons) based on a 60% probability threshold from a bioclimatic model. Whitebark pine 

distribution in the Greater Yellowstone Area, calculated from the same model, is shown in green (Warwell, Rehfeldt, and Crookston 2007).
28 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

management actions in these states. Less reconnaissance 

work has been done in California, Nevada, Oregon, and 

Washington; whitebark pine occurs on several isolated 

ranges on BLM lands in Nevada (Charlet 1996) and 

eastern California but has not been fully mapped or 

inventoried. (See Appendix 1.)

Screening tools that can be used to identify potential 

whitebark pine populations include:

1) Local knowledge and Resource Management Plan 

vegetation maps

2) Atlas of United States Trees (Little 1971), 

http://www.fs.fed.us/nrs/atlas/littlefia/

3) Forest Inventory and Analysis National Program, 

http://www.fia.fs.fed.us/

4) LANDFIRE and vegetation mapping product links, 

http://www.landfire.gov/vegetation.php

5) National Gap Analysis Program (GAP)/Land 

Cover Data Portal, http://gapanalysis.usgs.gov/

gaplandcover/viewer/

6) The Atlas of Nevada Conifers (Charlet 1996)

7) Research on Forest Climate Change: Potential Effects 

of Global Warming on Forests and Plant Climate 

Relationships in Western North America and Mexico, 

http://forest.moscowfsl.wsu.edu/climate/ (includes 

current and projected whitebark pine distribution 

maps) 

8) United States National Vegetation Classification 

Standard, http://usnvc.org/overview/

9) Individual states’ natural heritage programs may 

have additional locations and information on 

whitebark pine stands and communities

This suite of existing resources (i.e., remote sensing 

imagery, vegetation and bioclimatic models) may be 

used with aerial surveys and ground confirmation to 

map extent. Spatial data must be stored in a Geographic 

Information System (GIS) database at the state level for 

transmission to the National Operations Center in Denver 

and to the BLM’s Washington Office forestry lead. 

Inventory

After and/or concurrent with mapping, forest inventories 

should be initiated to document the status and trend of 

whitebark pine communities. Forest inventory is based on 

a set of objective sampling methods designed to quantify 

stand structure, spatial distribution, species composition, 

and other forest attributes (e.g., growth, pathogen or 

insect presence, fuels, vascular plant understory) within 

specified levels of precision (Society of American Foresters 

1998). If inventories are repeated, they can be used to 

calculate rates of change. 

The primary objectives of inventory and monitoring are to 

document: 

•	 Levels of white pine blister rust infection

•	 Overstory and understory species composition

•	 Age and stand structure

•	 Natural and planted seedling survival

•	 Level of mountain pine beetle infestation (none,

endemic, epidemic) 

•	 Fuel loads

Forest inventories, commonly known as “stand exams,” 

should be compatible with current BLM databases, such 

as FORVIS, and with future potential databases, such as 

EcoSurvey and MicroStorms. Walk-through assessments 

are also acceptable provided they meet specific objectives. 

Training field personnel to identify white pine blister rust 

symptoms and mountain pine beetle activity is imperative 

for successful inventory and monitoring efforts. USFS 

Forest Health Protection pathologists and entomologists 

are the best choices for instructors. They have systematic 

protocols for identifying severity of blister rust and attack 

status of mountain pine beetles. An example of blister 

rust severity ranking and mountain pine beetle activity 

rating is provided in Appendix 2. 

Once information is in FORVIS, it can be exported to 

the USFS Forest Vegetation Simulator (FVS) and used 

for answering questions about natural succession, 

disturbances, and management actions (http://www.

fs.fed.us/fmsc/fvs/). FVS is a suite of growth simulation 

models developed over decades and based on scientific 

knowledge and natural resources research and 

experience. Different geographic areas of the country are 

represented as “variants,” and numerous supplementary 

extensions to the base models can be used to analyze the 

effects of disease, insects, and fire.

In 2010–2014 approximately 1,300 ac of whitebark pine 

habitat were inventoried with stand exam methods on 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 29

BLM lands in Idaho (624 ac), Montana (445 ac), and 

Wyoming (218 ac). Fixed-area plots (1/10-ac plots for trees 

greater than 5 in. dbh), and nested plots (1/100-ac plots 

for trees less than 5 in. dbh) were used to record tree size, 

age, and disease and insect conditions (primarily blister 

rust and pine beetle), habitat type, and other tree-level 

and stand-level metrics. Species compositions for 

20 whitebark pine–dominated stands in Idaho and 

Wyoming are shown in Figure 3.5. 

Currently, a stand-alone FORVIS database and a master 

Microsoft Excel file houses all BLM whitebark pine and 

limber pine information at BLM state offices. The Excel 

files include scores of graphs and pivot tables displaying 

common stand exam metrics. These are housed at BLM 

state offices and are also available on the BLM’s internal 

website (https://blmspace.blm.doi.net/oc/sites/forestry/

Shared%20Documents/Forms/AllItems).

Monitoring

Monitoring is the collection of information over time, 

generally on a sample basis, by measuring change in an 

indicator or variable (Society of American Foresters 1998). 

In addition to inventories, the installation of fixed-area belt 

transects, primarily for monitoring of white pine blister 

rust infection levels, are widely used in the western United 

States and Canada. There are several commonly accepted 

transect methods:

1) The Greater Yellowstone Whitebark Pine Monitoring 

Working Group housed under the Greater 

Yellowstone Network (GRYN), http://science.nature.

nps.gov/im/units/gryn/monitor/whitebark_pine.cfm;

http://whitebarkfound.org/wp-content/

uploads/2013/10/GYE_Whitebark_Monitoring_

Protocol_June_2011_Version1_1.pdf

2) Whitebark Pine Ecosystem Foundation (WBPEF) 

protocol, http://whitebarkfound.org/wp-content/

uploads/2013/07/Methods-for-Surveying-andMonitoring-Whitebark-Pine-for-Blister-Rust.pdf

3) The Forest Insect and Disease Tally program (FINDIT) 

(Bentz 2000) is another method for monitoring 

conditions, particularly mountain pine beetle 

infestations; Forest Health Protection, USFS Region 

1, Missoula, Montana, is coordinating efforts to 

update and maintain the FINDIT program

We recommend following the GRYN protocol for 

a 10-year re-measurement schedule, to track the 

emergence and level of the primary risk factors and to 

quantify them spatially and temporally. A new “rapid 

assessment” method has been developed by the GRYN 

team and is being tested on BLM lands in Wyoming, 

within the Greater Yellowstone Ecosystem (see 

Appendix 3 for results). 

Figure 3.5 Species composition from 14 stands in central Idaho and 6 stands in Wyoming. Light green represents whitebark pine; aqua, subalpine fir. This 

is an example of information summarized from forest inventory (BLM FORVIS–fixed plot stand exams completed during 2011–2014 in Idaho, Montana, and 

Wyoming). 
30 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Measurements from inventory and monitoring can be 

used to determine: 

•	 Susceptibility and risk of mountain pine beetle

infestation

•	 Clark’s nutcracker presence

•	 Targets for thinning other conifers

•	 Site potential for planting rust-resistant seeds or

seedlings based on vascular plant cover

•	 Wildfire risk

•	 Targets for prescribed burning

Stand-level metrics have been used in a few studies to 

quantify whitebark pine stand susceptibility to mountain 

pine beetles and to predict Clark’s nutcracker occurrence. 

Mountain pine beetle outbreaks in host pines, including 

whitebark pine, have been positively correlated with 

large-diameter pines and stand density (Perkins and 

Roberts 2003). Probability of a stand being attacked by 

mountain pine beetles in the widespread epidemic of the 

1930s was 100% for climax whitebark pine stands that 

exceeded a basal area of 45 ft2/ac or a Stand Density 

Index (SDI) of 80 (Perkins and Roberts 2003). 

For nutcracker occurrence, McKinney, Fiedler, and 

Tomback (2009) equated cone density (~400 cones/ac 

[1,000 cones/ha] to a minimum basal area of 

22 ft2/ac [5.0 m2/ha]), with a preferred basal area of 

65 ft2/ac [15 m2/ha] of whitebark pines for the likelihood 

of seed dispersal by Clark’s nutcracker. Barringer et al. 

(2012) found a lower minimum basal area of greater 

than 9 ft2/ac (2.0 m2/ha) needed for cone production 

to support Clark’s nutcracker visitation reliably. The 

results from these studies may serve as guidelines for 

thinning to reduce risk of mountain pine beetle and for 

retaining sufficient mature, cone-bearing trees to attract 

Clark’s nutcrackers (see Section 3, Conservation Actions, 

“Silvicultural Practices”).

Gene Conservation 

The full genetic diversity across the range of whitebark 

pine should be preserved for the future by collecting and 

archiving seeds and growing and planting genetically 

diverse seedlings that also have resistance to blister 

rust. Trees that are putatively resistant to blister rust are 

called plus-trees. Superior (or elite) trees are individuals 

with proven rust resistance documented in screening 

trials or with genetic methods. Plus-tree collections, 

as well as bulk collections, should be archived for 

gene conservation at the USDA, Agricultural Research 

Service (ARS), National Center for Genetic Resources 

Preservation and should be coordinated with BLM’s Seeds 

of Success (SOS) program, consistent with the “National 

Native Seed Strategy for Rehabilitation and Restoration, 

2015–2020” (BLM 2015). As previously mentioned, 

seeds should be stored for blister rust screening trials and 

for growing seedlings for operational plantings. Seed 

inventories should be periodically assessed for viability 

and to ensure that effective population sizes are being 

maintained. With adequate seed supplies, the BLM and 

cooperators can provide diverse genetic resources that 

would enable the species to adapt to a changing climate 

or other stressors. 

Tree seed collections from the BLM have historically 

been processed in the BLM’s forest nurseries or with 

cooperators in USFS nurseries and regional cooperatives 

(e.g., Inland Empire Tree Improvement). Additional 

opportunities for long-term storage of whitebark and 

other five-needle pine genetic resources are available 

through the BLM’s SOS program (http://www.blm.

gov/mt/st/en/prog/botany/sos.html). As part of the 

federal interagency Native Plant Materials Development 

Program, SOS supports and coordinates seed collection 

of native plant populations in the United States. The 

goal is to partner with the seed-producing industry to 

increase the number of species and the amount of native 

seed available for stabilizing, rehabilitating, and restoring 

lands in the United States. A whitebark pine preservation 

orchard has been established at the BLM’s Tyrrell Seed 

Orchard in Eugene, Oregon (contact the BLM-Oregon 

forestry lead). Agency cooperators are listed in Table 2. 

The BLM, in addition to collecting, testing, and storing 

seed, also needs scion and pollen for seed orchard 

root stock and for clone banks. See Appendix 4 for 

instructions on collecting scion and pollen. Parent tree 

selections possessing desirable characteristics of blister 

rust resistance, cold hardiness, and mountain pine 

beetle tolerance are traits currently being evaluated at 

USFS nurseries, universities, and USFS and ARS forest 

genetic facilities (Table 2). Scion and pollen collection 

target trees are selected by USFS geneticists and tree 

improvement specialists. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 31

Cone Collection for Rust Resistance – 

Plus-Tree Selection 

The most important action in restoring whitebark pine 

is to ensure that future populations of the species are 

resilient to white pine blister rust, by increasing the 

frequency of trees with genetic resistance to the blister 

rust pathogen. All conservation plans and activities must 

first address how natural or planted whitebark pine 

regeneration will survive with blister rust. The BLM should 

1) support selective breeding programs to develop and 

plant blister rust-resistant whitebark pine, and 2) facilitate 

and accelerate natural selection for blister rust-resistant 

genotypes in stands using proactive restoration strategies 

(Schoettle and Sniezko 2007; Keane et al. 2012). 

The first step is to identify the plus-trees as permanently 

designated leave trees that are phenotypically resistant 

to blister rust. These plus-trees are easiest to identify in 

stands where blister rust incidence is high, because they 

have been exposed to the rust for longer periods of time 

and therefore have demonstrated a higher frequency of 

resistance to rust (i.e., no, to low levels of, symptoms) than 

uninfected stands or recently infected stands. In uninfected 

or recently infected stands it is difficult, if not impossible, 

to identify trees that are phenotypically resistant to rust 

(all trees look healthy). Only during multiyear experimental 

testing, when seedlings are exposed to blister rust spores, 

will individuals prove their level of resistance. When 

selecting plus-trees, look for trees that: 

•	 Have no, to low levels of, blister rust

•	 Are dominant or co-dominant trees

•	 Have potential to bear cones

•	 Are free of insects and disease

•	 Have a single stem where possible

•	 Are within 400 ft of trail or road

•	 Are at least 300 ft apart, to avoid relatedness

•	 Are safe to climb to collect seed

Complete procedures and details can be found in 

Mahalovich and Dickerson (2004) (http://www.fs.fed.

us/rm/pubs/rmrs_p032/rmrs_p032_181_187.pdf). In the 

northern Rocky Mountain region, synchronous abundant 

cone crops (masting years) occur every 2–4 years, with 

an average of 3.2 years (M.F. Mahalovich, pers. comm.). 

The most efficient and economical collections are usually 

made when most trees are producing cones. To date, 

the BLM has identified 51 whitebark pine plus-tree 

candidates in Idaho, Montana, Oregon, and Wyoming 

(Appendix 5).

Protection of Seed Sources

High-value individuals (e.g., plus-trees and old growth 

trees) and a diverse suite of age classes need protection 

from mountain pine beetle, unwanted wildfire, and 

timber cutting, so that the seed can be harvested into the 

future, and ecosystem structure is preserved. Old growth 

whitebark pines on BLM lands should be protected from 

fire and other disturbances to the extent possible, and 

mapped in a geographical information system (GIS). 

Protection from mountain pine beetle may include either 

insecticide application or anti-aggregating pheromones 

to protect individual high-value trees, small groups of 

trees, or larger areas. The insecticide Carbaryl provides 

nearly 100% protection from pine beetle infestations 

when applied according to manufacturer specifications, 

and is useful where seed tree locations are accessible 

Table 2. Facilities that extract seed, store seed, sow and grow seedlings, conduct white pine blister rust research, and/or develop seed orchards in the 

Northwest and intermountain regions. 

Cooperators Agency – location Services

Tyrrell Seed Orchard BLM - Eugene, OR Growing, orchards, 

BLM’s Whitebark Pine Preservation 

Orchard

Horning Seed Orchard BLM - Colton, OR Growing, orchard

Bend Seed Extractory USFS - Bend, OR Seed extraction 

Dorena Genetic Resource Center USFS - Cottage Grove, OR Genetics, rust screening, growing

Coeur d’Alene Nursery USFS - Coeur d’Alene, ID Rust screening, growing

Forest Service National Forest 

Genetics Laboratory

USFS - Placerville, CA Genetics, rust screening, growing

National Center for Genetic 

Resources Preservation 

USDA, ARS - Ft. Collins, CO Molecular testing, genetics,

long-term storage
32 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

by vehicles. Even where access is 

limited, a pack animal sprayer, like 

the one developed in USFS Region 

1, may be used to spray Carbaryl. 

An alternative, especially useful 

in remote locations, is the antiaggregating pheromone Verbenone, 

or Verbenone with additives (Progar 

et al. 2014; Perkins, Jorgensen, and 

Rinella 2015; Kegley et al. 2003; 

Kegley and Gibson 2004; Kegley and 

Gibson 2009; Fettig et al. 2012), 

which may be delivered several ways 

for stand- or tree-level protection 

(Bentz et al. 2005; Progar et al. 

2014). An annual application of 15 g 

(two 7.5-g pouches) of synthetically 

produced Verbenone doubled 

survivorship throughout a 7-year 

mountain pine beetle outbreak 

(Perkins, Jorgensen, and Rinella 

2015) (Figure 3.6). Other delivery 

systems include aerial application of 

Verbenone in small flakes (Gillette 

et al. 2012) and Verbenone with 

additives such as SPLAT (Progar et 

al. 2014). We suggest that the BLM 

consult with USFS Forest Health Protection entomologists 

and pathologists for expertise and updates on tree 

protection methods. 

To protect high-value trees from wildfire, we recommend 

removing live and dead fuels within one to several tree 

height distances from the target high-value tree. Fuel 

specialists must be consulted to determine clearing 

distances. Plus-trees, old growth, and other high-value 

tree geolocations should be given to fire management 

personnel in GIS formats, stored at BLM state, district, 

and field office levels, and made part of the Fire Resource 

Advisor package that the field office usually provides to 

fire incident personnel. 

Timber harvest plans should specify no cutting of 

whitebark pine. Where whitebark pine exists within a 

timber sale’s boundaries, Section 42, Special Provisions, 

of the contract should state that no cutting or other 

disturbance of whitebark pine is permitted.

Silvicultural Practices

Silviculture is the art and science of controlling the 

establishment, growth, composition, and quality of forest 

vegetation for the full range of forest resource objectives 

(Society of American Foresters 1998). As an important 

component of its management and conservation efforts, 

the BLM should consider for silvicultural treatment those 

whitebark pine forests that are declining from the impacts 

of disease, insects, or advanced succession.

The natural disturbances that shape whitebark pine 

landscapes, as discussed in Section 2, Disturbances and 

Threats, can be simulated at different scales to restore 

and conserve the species. Both prescribed fire and 

silvicultural thinning treatments can be used to simulate 

natural site preparation where natural seed sources are 

distant, and nutcracker visits are unlikely or uncertain, 

or where whitebark pine cone production is declining. 

Planting rust-resistant seedlings will augment natural 

regeneration where it might not otherwise occur.

Figure 3.6 Verbenone, an anti-aggregating pheromone used to deter mountain pine beetles from 

attacking whitebark pines, is stapled to the northwest and northeast sides of a mature tree. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 33

Figure 3.7 Hardware cloth cages were installed to protect the cones of this whitebark pine from predation by Clark’s nutcrackers and squirrels. Cages 

were removed in early September, when cones were harvested. Seed was sent to USFS nurseries for growing seedlings to be used in screening trials for 

white pine blister rust resistance. This tree exhibited no symptoms of blister rust infection and has been identified as phenotypically rust-resistant (i.e., a 

plus-tree) until screening trials can confirm that it is resistant (i.e., an elite tree) or discount this. BLM-Idaho, Cottonwood Field Office.

Silvicultural treatments emphasized in this section are:

•	 Collecting cones (seed)

•	 Planting rust-resistant seedlings to accelerate the

effects of selection 

•	 Thinning to reduce competing conifer vegetation to

increase the vigor (growth) of whitebark pine 

•	 Use of prescribed fire and wildfire

Cone Collection 

Cone collections from plus-trees for operational 

collections are described in the Whitebark Pine Cone 

Collection Manual (Ward, Shoal, and Aubry 2006a) 

(http://ecoshare.info/uploads/whitebarkpine/Cone_

Collection_Manual.pdf). BLM tree climbers are certified 

through the USFS National Tree Climbing Program, 

described at http://www.fs.fed.us/treeclimbing/intro/2/. 

Individuals work in pairs to climb trees without damaging 

the tree (i.e., no spurs and with light shoes), using 

orchard ladders and custom-made tree-tongs (Davies and 

Murray 2006). 

After trees are identified for collection, hardware cloth 

cages must be used to protect the cones from seed 

predation by Clark’s nutcracker, squirrels, and other 

animals. Instructions for constructing hardware cages 

are given in the Ward, Shoal, and Aubry (2006a) cone 

manual. Cages should be placed over immature cones 

in early summer, generally mid to late June (Figure 3.7). 

Cones mature/ripen in late summer. The method to 

determine seed ripeness is to cut seeds longitudinally 

and confirm that the embryo fills 90% or more of the 

embryo cavity (Burr, Eramian, and Eggleson 2001); 

however, a cavity that is filled 75% or more may yield 

acceptable germination rates. Cutting cones in half with 

a cone cutter will reveal the half-section face with seven 

to eight seeds, and is the easiest method to inspect the 

embryos. Once cones are ripe, the cages are removed and 

cones are collected and put in burlap sacks or equivalent 

breathable material. Repeated visits to determine cone 

ripeness are time-consuming, but because cones are 

caged, collections can occur after seed maturation. 
34 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

To prevent infection from insects or pathogens, no cones 

should touch the ground; tarps placed beneath collecting 

areas are needed. For plus-tree collections, all cones from 

the same tree must be in their own sacks. The sacks 

should be underfilled, approximately 1/3–1/2 full, with 

the tie closure within 3 in. of the top to allow adequate 

ventilation. Sacks must have tree cone collection tags 

(identification number, locations, administrative unit, etc.) 

inside the bag and also tied to the outside. It is critical to 

store sacks of cones in a dry, well-ventilated environment 

until they are shipped to nurseries and the seed is 

extracted (Figure 3.8; Appendix 6). 

Once seed is available from production seed orchards, 

cone collections should shift from the field to the 

seed orchards that have been designed for improved 

blister rust resistance, broad adaptability, and minimal 

inbreeding. 

We recommend that the BLM allocate funding for:

•	 Long-term, rust-resistant testing of whitebark pine

seed lots

•	 Seed orchard development and maintenance with

agency partners 

Seed Transfer

Seed transfer zones have been developed to minimize 

maladaptation risks of geographic and climatic variables 

to acceptable levels (Aubry et al. 2008; Bower and Aitken 

2008; Mahalovich and Dickerson 2004). Plantings of seeds 

and seedlings from rust-resistant stock must be obtained 

from within the seed zone where planting will occur. 

Mahalovich, Burr, and Foushee (2006) have currently 

identified four whitebark pine seed zones that cover the 

Inland Northwest, where most of the BLM’s whitebark 

pine populations occur (Figure 3.9).

1) Bitterroots - Idaho Plateau (BTIP)

2) Central Montana (CLMT)

3) Greater Yellowstone - Grand Teton (GYGT)

4) Inland Northwest (INLA)

BLM field offices should partner with national forests in 

their respective seed zones to develop seed orchards and 

secure future rust-resistant seed sources. BLM offices in 

Montana and Wyoming have entered into an agreement 

with the Greater Yellowstone Coordinating Committee for 

whitebark pine conservation. As part of this agreement, 

the Gallatin National Forest is establishing a whitebark 

pine orchard to produce sufficient genetic diversity of 

Figure 3.8 The easiest method to inspect embryos for seed maturity is to cut cones longitudinally in half with a cone cutter, revealing the half section faces 

of seven to eight seeds. Seeds are mature when the embryo fills 90% or more of the embryo cavity. Once ripe cones are harvested, they are put in burlap sacks 

or equivalent breathable material and stored in a well-ventilated space to dry. 

Cones stored in burlap sacks and hanging in

well-ventilated space to air-dry

Split cones expose the seed face
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 35

Figure 3.9 Four whitebark pine seed zones that cover most of the BLM’s whitebark pine populations.
36 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

seeds from rust-resistant seed sources. Both BLM-Montana 

and BLM-Wyoming will have access to seeds in the GYGT 

zone when the orchard becomes operational.

Planting

Overview

When seeds from rust-resistant parent trees become 

available in the appropriate seed zones for BLM areas, we 

recommend growing seedlings for planting in openings 

created by wildland fire, prescribed fire, or mechanical 

treatments, and “in-plantings” after mountain pine 

beetle outbreaks. 

Seedlings should be planted in the autumn, to avoid 

summer drought stress, at approximately 200–250 

seedlings per acre, with the goal of having 3- to 5-year 

survival of 85–100 trees per acre. It is critical that initial 

site preparation be done to remove competing vegetation, 

using prescribed fire or mechanical methods such as 

thinning and scalping.

Planting seedlings has yielded higher long-term survival 

rates than direct sowing of seeds (DeMastus 2013). 

Where access and cost is not prohibitive, planting of 

seedlings is the preferred method. Otherwise, direct 

sowing of warm-stratified seed from rust-resistant stock 

is recommended. Seeding trials conducted on six sites 

in western Montana and northern Idaho found that 

seeds treated with warm stratification procedure had 

51% germination and survival rates over a 2-year period, 

compared with a 33% for controls; 44% for warm 

stratification and scarification; and 18% for scarification 

only (Schwandt and DeMastus 2011). 

Planting Guidelines 

The following are planting guidelines adapted from 

McCaughey, Scott, and Izlar (2009): 

1) Plant large, hardy seedlings with well-developed 

root systems. Seedling vigor is important for both 

survival and growth of planted seedlings.

2) Reduce overstory competition. Although there are 

no defined basal area or trees-per-acre guidelines 

for overstory removal, experience suggests removing 

all overstory trees within a minimum 20-ft radius 

around the planted seedling.

3) The planting design should be a patchy pattern with 

densities similar to that of nearby stands. Microsite 

placement is critical. The seedlings should be 

planted in a moist, protected microsite on the north 

side of a log, rock, or stump. 

4) Plant in habitats that support whitebark pine. 

Whitebark pine is outcompeted by other species 

on milder mid-elevation sites, but has a slight 

competitive advantage on high-elevation, 

windswept ridge tops with shallow soils.

a) Avoid planting in burned lodgepole pine 

stands. Lodgepole pine typically regenerates 

quickly with high seedling numbers and rapidly 

outcompetes whitebark pine.

b) Do not plant in “mixed plantings” with other 

conifers. Whitebark pine seedlings grow slowly 

and may eventually be suppressed by lodgepole 

pine, Douglas-fir, subalpine fir, and Engelmann 

spruce (Izlar 2007).

5) Reduce understory vegetation to make soil 

moisture and nutrients available. Competing 

vegetation such as grasses and sedges should 

be removed, or scalped, in a 2-ft radius around 

the planted seedling. Do not plant seedlings 

within 2 ft of beargrass. On more mesic sites, 

grouse whortleberry should be retained. (Lower 

elevation xeric sites may not have these vegetative 

components.)

6) Avoid planting in swales and where soils are deep. 

Gophers feed on roots and bury trees, so avoid 

planting in areas of deep soils and swales where 

they burrow. Ridge tops or exposed slopes are 

generally more suitable planting sites (McCaughey 

1993; Scott and McCaughey 2006).

7) In burned areas, remove overstory snags to prevent 

them from falling on seedlings. 

8) Plant when there is adequate soil moisture. Autumn 

plantings are preferred, so that planted seedlings are 

not subject to summer drought stress.

9) Ideally, out-plant only seedlings that have been 

inoculated with mutualistic ectomycorrhizal fungi, 

such as Siberian slippery jack, in the greenhouse 

or nursery (Lonergan, Cripps, and Smith 2014) 

(Figure 1.9).
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 37

Seedling Survival

Whitebark pine seedling survival depends on many 

factors. The lack of competition, the presence of 

Vaccinium species on mesic sites, and the protected 

microsite conditions that nutcrackers select appear to 

be the most important factors leading to survival in the 

plant communities studied (Izlar 2007; McCaughey, 

Scott, and Izlar 2009; Tomback et al. 2011). At the Dillon 

Field Office, BLM Montana, monitoring of a 2012 burn 

planted with whitebark pine seedlings in 2013 and 2014 

has shown 98% survivorship thus far (E. Guiberson, 

pers. comm.) (Figure 3.10). Follow-up monitoring of 

planted sites should provide estimates of survivorship, 

height, growth, and rust resistance. 

Density Management

Metrics

Density metrics such as basal area, trees per acre (or 

hectare), and Stand Density Indexes should be calculated 

after forest inventories and monitoring efforts. These 

metrics can be used to quantify stand structure and to 

develop silvicultural prescriptions for prescribed fire and 

thinning. In general, thinning whitebark pines is not 

recommended, because of the potential loss of rustresistant and genetically diverse individuals. However, 

under some circumstances, such as severe rust infections 

that have top-killed mature trees, removal of individuals 

is warranted. 

Density management is a critical factor in the 

maintenance and restoration of whitebark pine. Standlevel objectives must be characterized in terms of stand 

composition and structure. The overall silvicultural 

objective is to protect and preserve the population 

(stand) for its function and structure, not the individuals 

within it. Silvicultural treatments and management 

guidelines are described for limber and whitebark pines 

on BLM lands in Wyoming in Instruction Memorandum 

WY-IM-2011-041 (shown in Appendix 7).

Recently, Stand Density Index nomograms have been 

developed for whitebark pine from FIA data. SDI 

nomograms can be used to determine the condition 

of the stand in terms of crown closure, site occupancy, 

limits of self-thinning (site occupancy), and self-pruning 

levels. The SDI of a stand can also be calculated by using 

the Forest Vegetation Simulator. The maximum SDI for 

whitebark pine is 675, as calculated from a sample of 

Figure 3.10 Post-wildfire planting of whitebark pine seedlings in 2013 

at Windy Pass. BLM-Montana, Dillon Field Office. All seedlings were planted 

near stumps, fallen logs, and rocks, which protect them from environmental 

extremes. 
38 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

520 FIA plots (J. Long and J. Shaw, in press) (Figure 3.11). 

Prescriptions for whitebark pine should be a percentage 

of 675 SDI, depending on silvicultural objectives. 

Breakpoints are: 

•	 25% for crown closure/onset of competition

•	 35% lower limit of full site occupancy

•	 60% lower limit of self-thinning

•	 < 60% to maintain vigor and avoid self-thinning

•	 <25% to delay self-pruning

•	 >25% to promote self-pruning

Mechanical Treatments

Properly designed silvicultural thinning in whitebark pine 

stands can simulate the effect of mixed-severity and 

nonlethal surface fire (Keane and Arno 2001), create 

clearings for Clark’s nutcracker seed caching and natural 

regeneration, and create early seral conditions to reduce 

competition from shade-tolerant conifers. Treatment sizes 

and shapes should be similar to the patterns left by past 

fires, but should be planned in relation to the amount of 

available whitebark pine seed source in surrounding stands 

(Keane and Parsons 2010b; Keane et al. 2012).

Thinning treatments that remove competing overstory tree 

species are currently recommended to maintain or increase 

the presence of whitebark pine on suitable sites. Thinning 

may increase the vigor of existing whitebark pines and 

provide caching sites for Clark’s nutcrackers. Few studies 

have sufficient growth release information on whitebark 

pines following reduction of non–whitebark pine species; 

however, based on a small sample of trees (n=48), almost 

all trees showed an increase in radial growth following 

silvicultural cuttings (Keane, Gray, and Dickinson 2007). 

Diameter release was greatest in dense stands and in 

older and larger-diameter trees. Suppressed seedlings and 

saplings of poor vigor and less than 4 in. (10 cm) dbh may 

not release, but vigorous saplings are likely to release after 

thinning. Species most often targeted for removal include 

subalpine fir, Engelmann spruce, and lodgepole pine. 

Limber pine should not be removed, because it faces the 

same threats (e.g., white pine blister rust and mountain 

pine beetle) as whitebark pine. 

Because of the potential loss of blister rust resistance 

in a stand, any thinning of whitebark pine should be 

undertaken with care and only because of demonstrated 

need, such as a significant pine beetle infestation within 

the immediate area, or environmental stress that is 

causing widespread mortality, and only after consultation 

with a silviculturist. In cases such as these, a combination 

of the McKinney, Fiedler, and Tomback (2009) guidelines; 

Barringer et al. (2012) guidelines about basal area and 

cone production; and the Perkins and Roberts (2003) 

thinning guidelines should be used, with the resultant 

stands having a basal area greater than 9 and less than 

45 ft2/ac (10.3 m2/ha) (see Section 3, Conservation 

Actions, “Monitoring”). The preferred target trees for 

removal are those with blister rust cankers on the bole, 

on limbs within 6 in. of the bole, or with greater than 

50% crown loss. 

Another density management option that is more critical 

in the isolated disjunct BLM stands is the treatment of 

adjacent lower-elevation stands of mixed conifers to 

reduce density and fuel loadings. In the event of wildfire, 

thinned stands are more likely to produce a mixedseverity, patchy burn pattern throughout the stand 

rather than a stand-replacing crown fire. This is especially 

important for those stands more than 6.2 mi (10km) from 

another whitebark pine seed source (Keane and Arno 

2001). A stand-replacing fire in more distant stands may 

cause local extirpation, because of the lack of visitation by 

Clark’s nutcrackers to cache offsite seeds.

Disturbances such as mountain pine beetles outbreaks, 

avalanches, and wildfire can naturally thin stands. A 

twofold to threefold increase in the previous 3 years of 

meristem leader growth has been observed in whitebark 

and limber pine stands where pine beetles have killed as 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 39

Figure 3.11 A draft Stand Density Index for whitebark pine (Long and Shaw, in press).
40 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

much as 70% of the overstory (D.L. 

Perkins, pers. obs.) (Figure 3.12). 

With increases in wildfire frequency 

and mountain pine beetle outbreaks 

across the western United States 

beginning in 2000 (Gibson et al. 

2008), these natural disturbances 

may themselves act as thinning 

agents in some areas. 

Because whitebark pine stands are 

often found in Lynx Analysis Units, 

planning and implementation of all 

mechanical treatments, prescribed 

fires, and use of wildland fire for 

resource benefit (WFRB) should 

meet any conditions about the type 

and amount of disturbance allowed 

that emerge from USFWS-BLM 

consultation and Biological Opinions.

Prescribed Fire

Because wildland fire is the 

disturbance that shaped most 

whitebark pine landscapes, 

restoration treatments should be 

designed to mimic fire’s historical 

effects on whitebark pine habitats 

(Keane and Arno 2001; Perera, 

Buse, and Weber 2004). Both severe 

and large area fires can eliminate 

other subalpine conifers and their 

seed, and provide ideal conditions 

for nutcracker caching sites and 

subsequent natural whitebark pine 

establishment. A stand-replacing 

wildfire in 1966 at an elevation of 

approximately 9,500 ft (2,800 m) has 

regenerated into a nearly pure stand 

of whitebark pine (Figure 3.13). 

These areas may also be excellent 

sites for rust-resistant whitebark pine 

plantings, and in situations where 

natural seed sources are distant, or 

decimated from other disturbances, 

this is the best option.

Figure 3.12 BLM Forester Mike DeArmond examining growth release of whitebark pine advance 

regeneration in 2010. Apical meristem growth increased fourfold after the 2008 decline in a mountain 

pine beetle outbreak that produced overstory mortality.

Figure 3.13 Whitebark pine regeneration following a stand-replacing wildfire in 1966 on the 

Salmon-Challis National Forest. Photo taken in 2013 at Bald Mountain near Clayton, Idaho.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 41

Prescribed fire can be used to create areas for 

Clark’s nutcracker seed caching and natural 

regeneration, prepare sites for planting, and 

reduce competition. Prescribed fire can also 

be designed to mimic the three types of fire 

regimes common in whitebark pine forests 

and woodlands. The primary objectives of a 

low-intensity surface fire are to remove the 

competing conifer reproduction, to reduce dead 

and down fuel loading, to remove portions 

of the litter and duff to expose bare soil, and 

to recycle nutrients bound up in vegetative 

materials, while keeping the primary overstory 

components such as whitebark pine. Moderateintensity prescribed fire can be used to mimic 

mixed-severity fire (where passive crown fire 

behavior is common as dense patches of 

conifer crowns are torched), opening up niches 

for Clark’s nutcracker seed caching as well 

as removing the surface fuels. High-intensity 

prescribed crown fires are difficult to implement 

because of the extreme conditions required for 

ignition; they are very difficult to control and are 

not recommended.

Weather considerations, site preparation, and 

ignition methods for lighting prescribed fires 

in the subalpine zone where whitebark pine is 

a community component are described in the 

Range-Wide Strategy and also in Keane and 

Arno (2001) and Keane and Parsons (2010a 

and 2010b). Prescribed burning when soils are 

frozen and/or moist and when snow is still on 

the ground may prevent spread to nontarget 

vegetation. An early spring prescribed burn 

to eliminate subalpine fir from whitebark pine 

habitat is shown in Figure 3.14.

WFRB can be used effectively in whitebark pine 

ecosystems, particularly in those areas under 

wilderness management. To be most effective, 

the whitebark pine stands in these areas 

need to be evaluated and have specific fire 

management plans written for them with the 

applicable fire behavior and weather conditions 

for the desired outcomes. The increase in large, 

severe burns from warmer climates and drier 

Figure 3.14 Prescribed fire used to kill subalpine fir in early spring. Winter snowpack 

prevents fire from spreading from the target tree. Whitebark pine is visible in the upper left 

corner of the photo.

Photo by Peter Weir, USFS, Boise National Forest
42 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

conditions (see Section 2, Disturbances and Threats, 

“Climate Change”) may provide opportunities for 

whitebark pine establishment.

Mechanical fuel reduction treatments (thinning) in lowerelevation conifer stands that are adjacent to whitebark 

pine stands may be considered necessary to reduce 

the potential of high-severity wildfire behavior and to 

ensure a residual stocking level of whitebark pine. To 

develop a management plan with narrow fire behavior 

prescriptions, recommendations from McKinney, Fiedler, 

and Tomback (2009), Barringer et al. (2012), and Keane 

and Arno (2001) should be followed.

Prioritization of Stand Treatments

Different forest conditions (i.e., stand structures and 

ages, species composition, pathogen and insect levels) 

require a flexible, multipronged approach for prioritizing 

conservation activities. Adaptive management can be 

used to incorporate new information and uncertainty, 

such as changing climatic conditions.

The following factors must be considered for 

implementing conservation actions:

1) Presence of risk factors, such as white pine blister 

rust and mountain pine beetle

a) The level of blister rust infection (percent stand 

infected, severity of infections)

b) The level of pine beetle infestation (endemic, 

accelerating, epidemic, declining)

2) Successional stage of the stand

a) Seral

b) Climax

c) Species and composition and structure

3) Accessibility (by vehicle, foot, pack stock)

4) Past disturbance (fire, pine beetle outbreak, 

landslide, mining disturbance)

5) Wilderness and other land management directives

Table 3, adapted from the GYA Strategy, provides a 

method for ranking sites for protection or restoration. 

Protection refers to monitoring efforts, plus-tree 

identification, seed collection, Verbenone and Carbaryl 

treatments to protect from mountain pine beetle, 

thinning of competing conifers, and pruning blister 

rust cankers. Restoration includes such activities as 

site preparation, prescribed fire, planting, and density 

management of all conifers. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 43

Table 3. Stand-level priorities for determining protection or restoration actions, adapted from the GYA Strategy (2011), p. 13 

BLM WHITEBARK PINE STAND-LEVEL CONDITION ASSESSMENT

Scoring system to assist in determining need/priority for protection or restoration

Protect* Restore**

Stand Damage Agents (Canopy)

No current MPB activity, no recent canopy damage 5 0

Low endemic levels of MPB activity, low canopy damage (0%–10%) 5 0

Increasing MPB activity (transition from endemic to epidemic), low to moderate canopy (10%–50%) 5 0

High epidemic levels of MPB activity, high canopy damage (50%–100%) 0 5

Low/decreasing MPB activity, high recent canopy damage (50%–100%) 0 5

Low to no MPB activity, very high recent canopy damage (50%–100%) 0 5

WPBR nonexistent or incipient infection (0%–5%) 5 1

WPBR evident with branch cankers and occasional bole canker, moderate limb mortality in conebearing trees and reproduction2 3

WPBR extensive mortality (tree or limb) in cone-bearing trees and reproduction 0 5

Root rot (any species) or twig beetles (Pityophthorus spp.,

Pityogenes spp., Pityoborus secundus) present 3 1

Stand Damage Agent Score 0–25 0–25

Current Stand Structure 

Basal Area (WBP) 

Basal Area between 22 and 45 ft2/ac 5 0

Basal Area <22 ft2/ac 0 5

Basal Area >45 ft2/ac 3 3

Mixed conifer/WBP stand with mixed conifer dominant in overstory 2 2

WBP stand with recent mixed conifer expansion – reproduction/pole-sized conifers 5 0

WBP and mixed conifer open woodland structure 5 0

Recently burned WBP stands with adjacent WBP seed source 0 5

Recently burned WBP stands without adjacent WBP seed source 0 5

Reproduction >250 seedlings/ac 5 0

Reproduction <250 seedlings/ac 0 5

Current Stand Condition Score 0–25 0–25

Other Planning Considerations Yes No

Stand is within predicted future range of WBP as per SDM

Distance from other WBP stands 

<10 km (6.2 mi)

>10 km (6.2 mi)

Accessible by road or trail – within 1/4 mi

Wilderness Study Area/Wilderness/ACEC/RNA – other special designation

Threatened & Endangered/Special Status Species

Grizzly Bear

Lynx

Wolverine

Other

Sum of Y/N Other Planning Considerations 0–9 0–9

Total Score of Stand Damage Agents + Current Stand Structure

These totals can aid in determining the type of work to be done and other planning considerations when ascertaining feasibility. 

0–50 0–50

*Protect = monitoring, plus-tree identification, seed collection, Verbenone treatments, thinning of competing conifers, pruning, use of chemical repellents

**Restore = site preparation, planting, density management of all conifers

Scoring = 0 for least critical action, 5 for most critical action 

MPB = mountain pine beetle, SDM = Species Distribution Model, WPBR = white pine blister rust
44 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Three examples of conservation 

actions based on existing stand 

conditions are:

1) In the more mesic portions 

of the species’ range, blister 

rust was recently reported 

as increasing at 4.3% per 

tree per year Schwandt et 

al. (2013). Some BLM areas 

have stand infection rates as 

high as 43%. In these areas, 

conserving genetic resources 

by protecting rust-resistant elite 

trees, collecting seeds for rust 

screening, and planting rustresistant seedlings (or seeds) are 

priorities. 

2) In the more xeric portions 

of the range, where blister 

rust occurs at low levels, 

management priorities might 

focus on removing other 

conifers to facilitate whitebark 

pine dominance, pruning of 

blister rust branch and limb 

cankers, planting rust-resistant 

stock to increase resilience, and 

identifying and testing sources 

of potential rust-resistant stock. 

Rust screening trials should 

identify resistance in these 

asymptomatic populations.

3) If mountain pine beetle 

populations are high or 

accelerating, then individual 

tree or stand protection with 

anti-aggregating pheromones, 

pheromones with additives, 

and/or Carbaryl should be 

considered to protect some 

seed sources (Progar et al. 

2014; Perkins, Jorgensen, and 

Rinella 2015). 

Photo by Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 45

Summary

The key to successful whitebark pine conservation on BLM lands in the 

future is the planting of rust-resistant seedlings after wildland fires, whether 

these fires are controlled wildfires, uncontrolled wildfires, or prescribed fires. 

Planting after mountain pine beetle outbreaks may also be recommended, 

depending on the condition of suppressed regeneration. The genetic diversity 

of planted seedlings should be maximized to ensure whitebark pine remains 

on the landscape as the climate changes. Maintaining a diversity of age 

classes that contain rust-resistant whitebark pine is critical to sustaining the 

species over long periods, because it provides both the resilience to survive 

unwanted wildfires and the resistance to outbreaks, disease, and climate 

change. While estimates of the area occupied by whitebark pine on BLM lands 

are low compared with areas on USFS and NPS lands, the small but important 

contribution of range margin habitats and isolated populations deserves 

conservation, particularly in the face of climate change. Where seed sources 

are still healthy, we recommend a proactive management approach promoting 

blister rust resistance and genetic diversity, coupled with silvicultural thinning 

to improve whitebark pine vigor and encourage natural regeneration.

Managing with uncertainty—for example, climate change—requires an 

adaptive approach. Using adaptive management—that is, having the flexibility 

to change management actions based on results and new information—fits 

well with the following whitebark pine conservation and management actions. 

Plan activities. Design plans, including mapping, inventory, and possible 

treatments for restoring whitebark pine ecosystems. This includes locating, 

prioritizing, and scheduling areas to treat.

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, 

decreasing surface and canopy fuels using direct or indirect treatments, 

manipulating forest composition, and diversifying age class structure.
46 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Protect seed sources. Protect valuable rust-resistant, 

seed-producing whitebark pine from future mortality 

caused by disturbance, climate, and competition. 

Gather seed. Collect seed from trees that are proven 

rust-resistant, phenotypically rust-resistant, and in areas 

yet to be exposed to blister rust for archiving genetic 

diversity and variation, growing seedlings for operational 

planting, and possibly for direct sowing. Make collections 

throughout the range to capture the range of genetic 

diversity before it is reduced by various human activities. 

Identify putatively rust-resistant trees, and collect seed 

from those trees for the rust-resistance screening process 

needed for genetic rust-resistance breeding programs. 

Manage and periodically assess seed inventories 

to ensure that effective population sizes are being 

maintained in space and time. This will better position 

agencies to be proactive in conservation, and will provide 

a buffer for climate change. 

Grow seedlings. Grow whitebark pine seedlings from 

seed of proven (genetically tested in a rust screening) 

rust-resistant trees; document levels of rust-resistance 

performance in the parent trees and their seedlings; 

establish seed orchards; and plant seedlings in areas that 

have been treated with the appropriate site prescriptions. 

Plant seedlings. Plant rust-resistant seedlings and use 

direct sowing in treated or burned areas, especially 

in areas experiencing heavy whitebark pine mortality. 

Areas with few whitebark pine seed sources are not 

likely to produce enough seed to provide for nutcracker 

energy requirements and adequate whitebark pine 

regeneration. 

Monitor activities. Pre- and post-activity field sampling is 

critical to document the success and failure of restoration 

treatments. Analysis of periodic data obtained from 

monitoring is needed to assess: 

•	 changes in levels of blister rust

•	 changes in species composition

•	 seedling survival after planting

•	 changes in fuel load

•	 insect activity (mountain pine beetle and other bark

beetles)
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 47

Research and Management 

Needs

Genetics

Conservation biology emphasizes the maintenance of native gene pools as an 

important function in maintaining ecosystem and species integrity. Jackson 

and Betancourt (n.d.) state: “Finally, our results underscore the growing need 

to focus more on genotypes than species in biogeographic modeling and 

ecological forecasting.” With the growing awareness of climate change and its 

potential effects on tree species such as whitebark pine, the above statement 

underscores the long-term need for appropriate genetic studies to determine 

native gene pools. 

Because of the diversity of BLM whitebark pine populations, especially those 

disjunct stands on the range margin of the species, we recommend that, as 

funding becomes available, the BLM conduct a range-wide genetic survey 

of whitebark pine populations on BLM lands, emphasizing those disjunct, 

potentially unique stands along the range margins and at lower elevations. We 

recommend that this work follow the methodology developed by Potter et al. 

(2015) in their range-wide study of ponderosa pine. The USFS in the Pacific 

Northwest (Region 6) has done similar work in its whitebark pine populations. 

The USFS National Forest Genetics Laboratory in Placerville, California, would 

be a preferred cooperator because of its extensive experience. This work would 

identify unique populations that may require priority restoration efforts, and 

would provide the basis for developing refined Species Distribution Models for 

the different genotypes.

Development of genomic techniques for rapid testing of trees for genetic 

resistance to blister rust would save years of greenhouse work and would 

make proactive restoration planning far easier and less costly. Research should 

improve the restoration process by providing vital information on state-of-theart techniques and protocols that will hopefully make restoration efforts more 

effective and economical. For instance, are genetic markers available for white 

pine blister rust, or can they be developed? 

Livestock Grazing

Many areas in whitebark pine ecosystems were grazed by huge herds of sheep 

and cattle in the late 1800s and early 1900s. The recognition of unacceptable 
48 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

levels of disturbance to soils, vegetation, and watershed 

health has resulted in some grazing reductions (Willard 

1990). However, domestic livestock grazing continues 

in many areas, often in noncompliance with allotment 

guidelines, and its effects on whitebark pine are largely 

unstudied. 

Seedling Establishment

Survivorship and photosynthetic efficiency of 

1-year-old whitebark pine seedlings at treeline was 

positively correlated with forb and tree cover in field 

manipulations, except under alleviated water stress 

(Maher, Germino, and Hasselquist 2005). Young 

whitebark pine, Engelmann spruce, and subalpine fir did 

not have a negative response to surrounding vegetation. 

More research is needed on survival of seedlings, planted 

seeds, and the conditions that correlate with successful 

establishment.

Density Management

SDIs are currently being developed for whitebark pine 

(J. Long and J. Shaw, pers. comm.) (Figure 3.11) from 

FIA plot data. Their application to thinning and stand 

vigor has yet to be investigated. Thinning trees that are 

severely infected with white pine blister rust is sensible, 

but thinning trees of unknown resistance levels 

increases the potential loss of rust-resistant, cold hardy 

or mountain pine beetle–resistant stock. More research 

is needed on density management and stand dynamics. 

Climate Change

Managers will need to understand how climate change 

influences the life cycle of the blister rust fungal 

pathogen Cronartium ribicola and seed and cone insects. 

Research reports on how climate change affects fire 

frequency and intensity and the life cycle of mountain 

pine have been discussed briefly in this document. This 

work is ongoing, and further work is encouraged. 

Photo by Terry Spivey, USDA Forest Service, Bugwood.org
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 49

Appendixes

Appendix 1: Maps Showing Probability of Occurrence of Whitebark Pine 

on BLM Lands in Eastern Oregon and Western Idaho and in 

Eastern California and Nevada ........................................51

Appendix 2: White Pine Blister Rust Damage Codes for Ranking Severity 

of Infection, and Mountain Pine Beetle Activity Rating for 

Whitebark Pine................................................................53

Appendix 3: Monitoring Report for Health Status of Five-Needle Pines on 

Wyoming BLM Lands (Reprint).........................................55

Appendix 4: Scion and Pine Pollen Collection and Handling.................57

Appendix 5: Whitebark Pine Plus-Trees in Idaho, Montana, 

Oregon, and Wyoming ....................................................61

Appendix 6: Cone Collecting Guidelines..............................................63

Appendix 7: Whitebark and Limber Pine (Five Needle Pine) Management 

Guidelines for Wyoming BLM, August 2011 (Reprint) .......65

 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 51

Appendix 1 

Maps Showing Probability of Occurrence of Whitebark Pine on BLM Lands in 

Eastern Oregon and Western Idaho and in Eastern California and Nevada

BLM-Oregon (eastern) and BLM-Idaho (western) whitebark pine occurrence map (red polygons) based on a 60% probability threshold 

from a bioclimatic model. Green polygons represent all lands where whitebark pine occurs at a probability of 60% (Warwell, Rehfeldt, 

and Crookston 2007).
52 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

BLM-California (eastern) and BLM-Nevada whitebark pine occurrence map (red polygons) based on a 60% probability threshold from a bioclimatic model. 

Green polygons represent all lands where whitebark pine occurs at a probability of 60% (Warwell, Rehfeldt, and Crookston 2007).
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 53

Appendix 2

White Pine Blister Rust Damage Codes for Ranking Severity of Infection, and 

Mountain Pine Beetle Activity Rating for Whitebark Pine

Rust Severity Code for large trees, GREEN (live) trees only (> 5 in. dbh)

X = unable to see the top well enough to tell

S = Severe 

	 > 66% of crown dead,

and/or bole canker in lower portion of tree,

or if bole canker will likely kill > 66% of the cone-producing area

M = Moderate

33%–66% of crown dead 

or several (> 6) large dead branches or flags,

or bole canker in upper portion of tree that will cause only partial top kill

L = Light

	 < 33% of crown dead or a few small dead branches,

or occasional flags (< 6)

0 = No rust seen

Rust Severity Codes for small, live WBP (< 5 in. dbh)

D = Dead due to blister rust

DU = Dead for unknown reason (no obvious rust, etc.)

S = Severe (same as for larger trees)

> 66% of crown dead (or top kill),

and/or lethal canker in lower portion of tree,

or on a branch < 6 in. from bole

M = Moderate (same as for larger trees)

L = Light (same as for larger trees)

on very small trees, may see only a dead, swollen branch (often at the end of twig),

or flag > 24 in. from bole

0 = No rust seen; clean tree

Mountain Pine Beetle Activity Ratings

Mass attack = boring dust or pitch tubes surround most of the root collar or bole and/or the phloem and sapwood 

are discolored and beetle galleries and larval mines are visible around most of the bole following bark 

removal. Foliage may be green.

Strip attack = successful attacks confined to half or less of the tree’s circumference. 

Pitch out = trees with five or more large pitch tubes with little or no red, oxidized frass. No successful galleries 

under the bark. 

Live or = trees with no frass and fewer than five pitch outs. 

no attack
Photo by Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database/USDA NRCS. 1995. Public Domain
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 55

Appendix 3

Monitoring Report for Health Status of Five-Needle Pines on 

Wyoming BLM Lands (Reprint)

Prepared by Erin Shanahan, May 14, 2015

In 2013 and 2014 baseline data were collected to assess the overall health status of five-needle pines (whitebark pine 

and limber pine) on Bureau of Land Management (BLM) properties within the Greater Yellowstone Ecosystem (GYE). 

In portions of Wyoming, eight mapped units were identified as having a five-needle pine component. Mapped units 

contained both permanently established transects (for future revisit) and rapid assessment transects. (See Table 1.)

Of the 2,366 live trees surveyed, 107 were positively documented as whitebark pine (Pinus albicaulis, or “WBP”) and 

261 as limber pine (Pinus flexilis). Due to the absence of cones and their location in mixed stands of both WBP and 

limber pine, the species of the remaining 2,005 live five-needle pines was recorded as unknown (“UNK”). All fiveneedle pines were examined for white pine blister rust (blister rust, or “BR”) infection and sign of mountain pine beetle 

(“MPB”) infestation.

Using an unadjusted, combined ratio estimator with a secondary variance component to determine the proportion 

of five-needle pines infected with blister rust on BLM lands in the GYE, we found that 0.156 ± 0.054 (95% CI 

[0.045,0.268]) of five-needle pines were infected with blister rust. For whitebark pine only, the proportion of trees 

infected on BLM lands was 0.302 ± 0.17 (95% CI [0.00,0.703]). The confidence interval width for this estimate is 

reflective of the small sample size for whitebark pine. About 5% (0.048) of the live five-needle trees had sign of 

mountain pine beetle, and of the 786 dead trees, 712 (0.91) had galleries on the bole. The understory (< 1.4-m tall)

five-needle densities varied (0–441) across the eight mapped units, with a total of 1,272 observed. Of these, the 

incidence of blister rust was low (0.02).

Table 1. Numeric summaries of total trees recorded for each transect type for combined data from 2013 and 2014 field seasons. Total refers to the count 

of trees pooling across transects and map units.

Category Permanent Transects

Count Proportion

Rapid Transects

Count Proportion

Total map units 8 36

Total transects 8 137

Total trees 146 3,006

Total dead trees 7 779

Total WBP 12 96

Total Live WBP 12/12 (1.000) 95/96 (0.990)

Total Live WBP with BR 4/12 (0.333) 24/95 (0.253)

Total WBP with MPB 0/12 (0.000) 5/96 (0.052)

Total Limber Pine 20 246

Total Live Limber Pine 20/20 (1.000) 241/246 (0.980)

Total Live Limber Pine with BR 9/20 (0.450) 85/241 (0.353)

Total Limber Pine with MPB 0/20 (0.000) 6/246 (0.024)

Total UNK trees 114 2664

Total Live UNK trees 114/114 (1.000) 1891/2,664 (0.710)

Total Live UNK trees with BR 15/114 (0.132) 457/1,891 (0.242)

Total UNK trees with MPB 2/114 (0.018) 141/2,664 (0.053)
56 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Earlier, in 2004, an interagency whitebark pine long-term monitoring program was established to detect and 

monitor changes in the health of whitebark pine populations across the GYE due to infection by blister rust, attack 

by mountain pine beetle, and damage by other environmental and anthropogenic agents. Data for this monitoring 

program are collected from 176 transects in 150 stands of whitebark pine across the GYE. Currently, the proportion 

of live, whitebark pine trees > 1.4-m tall infected with blister rust is 20%–30%. This range includes the confidence

interval for the estimate. Infection is defined as a single canker to multiple on a given tree. From this ground-based 

monitoring approach, we report that as of 2013 about 27% of whitebark pine has died in the GYE since 2004. 

Mountain pine beetle infestation was evident on 833 (0.58) of the 1,443 dead trees. Understory counts on the 176 

transects totaled more than 8,000 trees and ranged from 0 to > 600 on a given transect. Blister rust infection was

low in this size group. 

On six of the eight mapped BLM units, we found whitebark pine to be a minor stand component in conjunction with 

limber pine and other conifer species. Whitebark pine on the monitoring program transects are typically found in mixed 

and pure stands of whitebark pine and other species. Limber pine is rarely encountered in the monitoring program 

stands. During the two seasons of data collection on BLM-managed lands, cone production was almost nonexistent for 

trees on all of the eight mapped units, as 2012 had evidently been a mast year. Elevation ranges for BLM transects went 

from 5,900 to 9,400 feet, whereas the span for the monitoring program transects starts at 7,800 feet and goes up to 

10,400 feet. 

The rate of infection in whitebark pine populations on BLM-managed lands is similar to rates reported for whitebark 

pine in other areas of the GYE. At least two (Commissary Ridge and Pine Grove/Deadline) of the eight mapped units 

were located within close proximity to several of the monitoring program transects. Though infection proportions were 

similar in both areas, we noticed that blister rust infection appeared to be fairly recent throughout most of the eight 

mapped units on BLM lands. This was deduced based on the fact that most infections were located in the canopies of 

infected trees and there was an absence of flagging in association with these branch cankers. 

Although mountain pine beetle related mortality in five-needle trees was relatively higher on BLM trees than the 

monitoring program trees (0.91 compared with 0.58), there was a higher incidence of mountain pine beetle on the 

monitoring program transects (0.71) compared with the BLM transects (0.52; monitoring program = 126/176, BLM = 

76/145). One reason for this difference could be that the most recent mountain pine beetle outbreak seems to have more 

heavily impacted five-needles in some of the southern portions of the GYE close to where the BLM transects are located. 

Regeneration densities are fairly comparable for both BLM and other GYE areas.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 57

Appendix 4

Scion and Pine Pollen Collection and Handling

Scion Collection and Handling

The following is a list of guidelines for selecting and collecting scion material to be used in future grafting projects. 

1) Collect scion material from the upper third of the tree crown ONLY. Female flowers are most often produced in 

the upper third of the tree crown.

2) Collect scion material in the spring while the tree is still dormant. Collect scion material from wood that grew the 

previous summer (1-year-old material). To ensure dormancy, all scion must be received at the Coeur d’Alene 

Nursery (CDA Nursery) by the close of business on March 20.

3) Ensure that scion measures 6–8 in. long to prevent dessication and allow enough material for grafting. Most grafting 

is done with 2-0 rootstock (two growing seasons). Scion caliper should match rootstock caliper as closely as possible, 

and this varies by species and year. In most years, the target scion calipers average 1/8 in. for western larch, 3/16 in. 

for whitebark pine, 3/16 in. – 1/4 in. for western white pine and lodgepole pine, and 1/4 in. – 5/16 in. for ponderosa 

pine. For thicker branched species, you may need to collect secondary and not primary branches. Do not force the 

scion to fit in the bag by trimming needles or bending the scion. If a 1-gallon ziploc bag is not big enough, 

use the 2-gallon ziploc bags now available.

4) Wrap the cut end of the scion material in wet paper towels. Do not put snow in the bag. Depending on 

the species, 10–20 pieces of scion from the SAME donor tree can be wrapped in wet paper towels (i.e., it is 

unnecessary to wrap each piece of scion individually).

5) Consult David Foushee (208-765-7394, dfoushee@fs.fed.us) at the CDA Nursery if you have questions about 

quantity of scion needed per individual, or other questions. 

6) Include two tags with each ziploc bag filled with scion, one on the inside and one attached to the outside. The 

tags should include one of the sets of information shown below:

a) White Pine Parent Trees from Wild Stand Collections

Species

Cycle Number

Tree Number

Collection Type (BO = Breeding Orchard, CB = clone bank)

Township, Range, Section

Elevation

Area Name

Forest and District Name

Full Name of Collector

Date of Collection
58 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

b) Collections from Field Tests, Plantations, and Tree Improvement Areas (all species)

Species

Breeding Zone

Phase (I or II)

Cycle Number (for white pine)

Stand and Tree Number

Pedigree Number

Collection Type (BO = breeding orchard, CB = clone bank, SO = seed orchard, VR = vertical resistance

study, etc.); purpose for the collection; where it will be out-planted. 

Plantation, Field Test, or Tree Improvement Area Name; if from a Tree 

Improvement Area, identify where the material was collected: early selection

trial (EST), clone bank (CB), or seed orchard (SO)

Replication (block), Row and Column of the Plantation, Field Test, or Tree Improvement Area

Forest and District Name 

Full Name of the Collector

Date of Collection

7) Create tags/labels before collecting scion in the field, for greater ease and to minimize mistakes in recordkeeping. 

Organizing the scion collection bags by how material is collected in a field test (e.g., serpentine fashion) will also 

speed up the collection process.

8) Place ziploc bags in coolers with frozen blue ice packs during the day when scion is being collected at the site. 

Do NOT use dry ice.

9) Scion material may be stored for 2–3 weeks in a refrigerator set at 34– 38 °F. Scion may be stored for 1–3 months 

at 32 °F. We recommend, however, shipping the scion within 24–48 hours after field collection.

10) Ship scion in coolers to keep the material at a cool temperature and to ensure that the material stays in good 

condition. An ice pack in the bottom of the cooler will keep the material cool during transport. If you cannot 

bring the material to the CDA Nursery, then you should ship it with an overnight express carrier. Avoid shipping 

on a Thursday or Friday, since doing so risks delaying delivery until the following week; material may not be kept 

in a cool environment over the weekend and become damaged. Remember, this material is living tissue that 

needs to be handled with extreme care. Please notify the CDA Nursery before shipping scion by calling 

208-765-7394 or -7375 (front desk), so the nursery can be ready to process it immediately. If delivering 

the scion material in person, be sure to make the delivery during posted business hours for the nursery

(7:30 a.m. – 4:00 p.m., Pacific time, Monday–Friday).

Shipping address:

David Foushee

USDA Forest Service

Coeur d’Alene Nursery

3600 Nursery Road

Coeur d’Alene, ID 83815-5279
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 59

Pine Pollen Collection and Handling

1) Locate trees and assess for pollen development. Flag elite trees ahead of time to facilitate relocation before actual 

pollen collections take place. Record as much pollen identification information on the outside of the bags ahead 

of time, to speed up actual field collections.

2) If you are collecting pollen from the same trees or the same locations in different years, when to monitor for 

ripeness can be based on past experience with adjustments made for that year’s climate. An “indicator” tree close 

to your office can also be used, based on past experience with that tree’s ripeness relative to target trees in the 

field. It is always better to be a little early and have to make a second visit than too late and have to wait until next 

year.

3) Hopkin’s Bioclimatic Law can be used to estimate pollen ripeness dates for trees in new locations relative to 

locations where ripeness dates are known. In general for the northern Rockies, pollen ripens:

•	 4 days later for each 1 degree latitude northward; 4 days earlier for each 1 degree latitude southward

•	 4 days later for each 5 degrees longitude eastward; 4 days earlier for each 5 degrees longitude westward

•	 4 days later for each 400-ft increase in elevation; 4 days earlier for each 400-ft decrease in elevation

This should be used as a general guideline only because of microsite differences such as aspect, cold air drainage, and 

the genetics of the tree (early ripeners vs. late ripeners).

4) Monitor catkins for signs of ripening. Be aware that you have about 24–36 hours to collect mature pollen before 

pollen flight. Things to keep in mind:

•	 Catkins turn from green to yellow in white pine and from reddish-purple to yellow in ponderosa pine.

•	 Trees ripen from the bottom up, unless there are cold air drainage problems (e.g., Hog Meadows).

•	 You can perform a squeeze test. (Squeeze a catkin between thumb and finger. If the liquid is yellow and/or

cloudy, the pollen is not ripe. If the liquid is clear, pick the catkins).

•	 If nearby neighbors are shedding pollen, and there is a risk of pollen contamination at the target elite 

tree due to air movement, do not collect pollen.

5) Place catkins in paper lunch bags or pollen bags. Seal seams with tape to avoid contamination with other pollen 

collections. Collect two–three bags of catkins per tree and do the following:

•	 Fill bags 1/3–1/2 full with catkins only—NO NEEDLES.

•	 Double-fold the top of the bag shut, and staple closed. Do not fold bags so far down that the catkins are packed

together with no “breathing room.” Seal the stapled fold with tape.

6) To avoid pollen contamination when moving from one elite tree to the next, sterilize all collection 

tools (snippers) and hands with rubbing alcohol and allow sufficient drying time before proceeding 

with the next collection. A new pair of disposable surgical gloves is recommended for hands in lieu of 

repeated skin contact with alcohol.

7) Do not collect catkins in the rain or in wet, extremely humid conditions. Doing so greatly increases 

the chances of mold growing on the catkins before the pollen can be processed at the nursery. Mold 

decreases pollen yield and viability.

8) Use red tape, or staple red flagging to the top of the bag to indicate “red tag” pollen lots that need to be 

processed for use that same field season. Also, write “red tag” on the bag.
60 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

9) Record collection and identification information with a waterproof marker.

a) Single-tree collections in stands (white pine) 

Record the following information on the bag:

Indicate if this is a “red tag” lot.

Collection Date _____/_____/_____

Species Code _________________

(2 alpha, WP )

TWN______ RNG______ SEC______ ELEV________

Cycle Number_________________

Family Number________________

Collected by_____________________________________

b) Plantation Collections (ponderosa pine) 

Record the following information on the bag:

Indicate if this is a “red tag” lot.

Collection Date _____/_____/_____

Species Code _________________

(2 alpha, PP )

Plantation Code________________ 

(4 alpha, e.g., LONE, COND, LUBR)

Breeding Zone_________________

Family Number________________

Pedigree Number_______________

Elite Tree Rep_______Row_______Col_________

Collected by_______________________________

10) (Temporary storage.) Keep bags cool and dry, out of direct sunlight while in the field. If unable to ship pollen 

within 24 hours, hang bags on a clothesline in a garage or warehouse, with clothespins, and be sure to shake the 

bags twice a day to ensure air circulation and minimize mold formation. Ship bags within 48 hours of collection.

11) Transport pollen collections in a cardboard box that is loosely packed with crumpled newspaper. Cut 2-in. 

diameter holes around the sides of the box for aeration. Tomato or apple boxes work well.

12) Ship pollen to Coeur d’Alene Nursery. Notify David Foushee (dfoushee@fs.fed.us, 208-765-7394) before shipping. 

Ship to arrive during posted business hours, 7:30 a.m. – 4:00 p.m., Pacific time, Monday–Friday. 

Shipping address:

David Foushee

USDA Forest Service

Coeur d’Alene Nursery

3600 Nursery Road

Coeur d’Alene, ID 83815-5279
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 61

Appendix 5

Whitebark Pine Plus-Trees in Idaho, Montana, Oregon, and Wyoming

These trees show few to no symptoms of blister rust, and their progeny will be tested for rust resistance. Cone 

collections and rust resistance screening at the USFS Coeur d’Alene Nursery is ongoing. 

Site Name Tree ID Field Office Seed 

Zone

WGS84_X

(long.)

WGS84_Y

(lat.)

Aspect 

(deg)

Elevation 

(ft) 

IDAHO PLUSTREES 

Marshall Mountain mmt373 Cottonwood BTIP -115.856 45.3874 332 7,969

Marshall Mountain mmt374 Cottonwood BTIP -115.856 45.3854 288 8,090

Marshall Mountain mmt375 Cottonwood BTIP -115.855 45.38493 280 8,155

Marshall Mountain mmt376 Cottonwood BTIP -115.855 45.38296 247 8,140

Marshall Mountain mmt377 Cottonwood BTIP -115.853 45.38157 292 8,208

Marshall Mountain mmt372 Cottonwood BTIP -115.857 45.37578 240 8,028

Marshall Mountain mmt371 Cottonwood BTIP -115.846 45.37428 349 8,438

Geertson Ridge Gee890 Salmon BTIP -113.696 45.24092 268 9,134

Geertson Ridge Gee893 Salmon BTIP -113.697 45.24053 297 9,077

Geertson Ridge Gee892 Salmon BTIP -113.696 45.24259 281 9,200

Geertson Ridge Gee891 Salmon BTIP -113.694 45.24391 287 9,258

Geertson Ridge Gee899 Salmon BTIP -113.716 45.22885 254 7,861

Geertson Ridge Gee898 Salmon BTIP -113.713 45.22941 183 8,014

Geertson Ridge Gee897 Salmon BTIP -113.708 45.23321 156 8,420

Geertson Ridge Gee896 Salmon BTIP -113.708 45.23445 186 8,600

Geertson Ridge Gee900 Salmon BTIP -113.721 45.22259 177 7,270

Poverty Flat Pov306 Challis BTIP -114.368 44.30389 153 9,430

Poverty Flat 6995 Challis BTIP -114.361 44.30763 60 9,306

Poverty Flat 7002 Challis BTIP -114.358 44.32006 12 9,415

Poverty Flat 7001 Challis BTIP -114.363 44.31652 186 9,416

Poverty Flat 7000 Challis BTIP -114.362 44.31566 179 9,407

Poverty Flat 6990 Challis BTIP -114.349 44.30224 80 8,799

Poverty Flat 6998 Challis BTIP -114.363 44.31104 109 9,362

Poverty Flat 6997 Challis BTIP -114.362 44.31033 99 9,326

Poverty Flat 6991 Challis BTIP -114.36 44.3053 66 9,303

Poverty Flat 6996 Challis BTIP -114.363 44.30971 70 9,394

Poverty Flat 7004 Challis BTIP -114.356 44.31794 77 9,411

Poverty Flat 7003 Challis BTIP -114.355 44.31652 165 9,376

Poverty Flat 6999 Challis BTIP -114.362 44.31456 170 9,388

Poverty Flat 6994 Challis BTIP -114.361 44.30644 71 9,319
62 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Site Name Tree ID Field Office Seed 

Zone

WGS84_X

(long.)

WGS84_Y

(lat.)

Aspect 

(deg) 

Elevation 

(ft) 

MONTANA PLUSTREES

Sweetgrass swe381 Hauvre CLMT -111.137 48.85406 81 6,777

Windy Pass 6341 Dillon CLMT -111.967 45.68635 8,000

Windy Pass 6342 Dillon CLMT -111.963 45.68608 8,000

Axolotl 6343 Dillon GYGT -111.903 45.19538 8,600

Axolotl 6344 Dillon GYGT -111.901 45.19819 8,600

Axolotl 6345 Dillon GYGT -111.887 45.21202 8,600

Medicine Lodge 6347 Dillon CLMT -113.055 44.77737 8,700

Upper Horse Prairie 6346 Dillon CLMT -113.15 44.90906 8,900

Upper Horse Prairie 6349 Dillon CLMT -113.155 44.91204 8,900

OREGON PLUSTREES

Hunt Mountain hunt701 Baker BTIP -118.058 44.8808 5 7,200

Hunt Mountain hunt702 Baker BTIP -118.058 44.88016 45 7,303

Hunt Mountain hunt703 Baker BTIP -118.058 44.87918 40 7,421

Hunt Mountain hunt704 Baker BTIP -118.058 44.8776 289 7,462

WYOMING PLUSTREES

Commissary Ridge com005 Kemmerer GYGT -110.577 42.0459 88 8,972

Commissary Ridge com006 Kemmerer GYGT -110.575 42.06562 278 9,304

Commissary Ridge com008 Kemmerer GYGT -110.569 42.08903 77 9,330

Commissary Ridge com007 Kemmerer GYGT -110.569 42.09004 32 9,310

Commissary Ridge com001 Kemmerer GYGT -110.573 42.06961 90 9,353

Commissary Ridge com002 Kemmerer GYGT -110.573 42.08523 181 9,298

Commissary Ridge com003 Kemmerer GYGT -110.574 42.08512 229 9,287

Commissary Ridge com004 Kemmerer GYGT -110.57 42.08237 347 9,367

BTIP – Bitterroots - Idaho Plateau

CLMT – Central Montana

GYGT – Greater Yellowstone - Grand Teton
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 63

Appendix 6

Cone Collecting Guidelines

1) Place cages over immature cones in early summer, generally mid to late June.

2) Cones mature/ripen in late summer. The method to determine method seed ripeness is to: 

a) Cut cones in half longitudinally (or sections) with a cone cutter to reveal the half section faces of seven to 

eight seeds. This is an easy method for inspecting the embryo. 

b) Cut seeds longitudinally and confirm that the embryo fills 90% or more of the embryo cavity (Burr, Eramian, 

and Eggleson 2001). A cavity that is filled 75% or better may also yield acceptable germination rates.

c) Repeated visits to determine cone ripeness are time-consuming, but because cones are caged, collections can 

occur after seed maturation.

3) Once cones are ripe, remove cages, collect cones, and put cones in burlap sacks.

a) To prevent cone infection from insects or pathogens, place tarps beneath collecting areas, so no cones touch 

the ground.

4) Store cones in burlap sacks or equivalent breathable material. 

5) For plus-tree collections, you must keep all cones from the tree in their own unique sacks.

6) Keep sacks underfilled, approximately 1/3–1/2 full, with the tie closure within 3 in. of the top, to allow adequate 

ventilation. 

7) Sacks must have tree cone collection tags (identification number, locations, admin unit, etc.) inside the bag and 

also tied to the outside. 

8) It is critical to store sacks of cones in a dry, well-ventilated environment until the cones are shipped to nurseries 

and the seed extracted. 
Photo by John Esworthy
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 65

Appendix 7

Whitebark and Limber Pine (Five Needle Pine) Management Guidelines for 

Wyoming BLM, August 2011 (Reprint)

Attachment 2 of Instruction Memorandum: WY-2011-041

These guidelines are developed to provide direction on how to manage both whitebark pine and limber pine found 

on BLM lands in Wyoming. The silvicultural prescriptions are to be used as guidelines to meet the objectives of the 

maintenance and restoration of five needle pine on the landscape. The objectives are: 1 - to maintain these stands on 

the landscape in the face of changing climate and insect (mountain pine beetle – MPB) and disease (white pine blister 

rust – WPBR) epidemics that are severely impacting these species, 2 - to maintain genotypic diversity on the landscape 

and 3 - to provide both the source and opportunity for these species to naturally migrate or change their species 

ranges as climatic conditions change in the future. Field Offices need to evaluate the objectives of projects that involve 

five needle pines to ensure that the long term objectives of maintaining these sensitive species on the landscape are 

appropriately evaluated along with other management objectives.

Reference materials that can be used for documentation of potential management actions can be found at: 

http://web.wy.blm.gov/930/forestry/pines/index.htm

Wyoming BLM is working with Utah State University to develop Stand Density Index Charts for both whitebark and 

limber pine. When these are completed they will be valuable tools with which to manage these stands. All Stand 

Density Index (SDI) materials can be found at: http://web.wy.blm.gov/930/forestry/SDI/index.htm

General Guidelines:

Cone (Seed) Collection: There are significant regional whitebark and limber pine seed collection efforts underway 

to identify white pine blister rust (WPBR) resistant trees. The cone collection efforts are central to five needle 

pine restoration for three reasons: 1 - blister rust resistance testing, 2 - restoration plantings, and 3 - ex-situ gene 

conservation.

Preliminary seed tree selection involves finding and marking trees that are nearly free of both WPBR and mountain pine 

beetle (MPB) infestation. Trees need to be marked and located with a Global Positioning System (GPS) so that they can 

be relocated for further collections if testing determines that these trees are WPBR resistant. This information will be 

stored on a GIS data layer at the District level. The entire process, from cone collection to rust resistance determination, 

takes approximately 5 years, so these trees need to be protected from both natural and human disturbance until the 

determination is made. If the testing shows WPBR resistance, these trees will be permanently marked and used as a 

seed source. These trees are identified as “plus” trees. All trees either tentatively or positively identified as “plus” trees 

need to be protected by pheromones or insecticides (see next page).

Whitebark pine seed collection procedures can be found in the online five needle pine references. Limber pine, 

because of its different cone structure, does not normally require the caging that whitebark pine does and can be 

collected as soon as the seed is ripe. In high pine mortality areas (limited seed source), where there is significant 

predation from squirrels and birds, caging of both species is necessary. Collections for both species is normally done, 

dependent on site and climatic conditions, in late August or early September when their embryo cavities are found to 

be at least 80 percent full.
66 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Because of the workload associated with identification of potential “plus” trees as well as the seed collection, it is 

recommended that Field Offices develop BPS submissions in conjunction with the “Seeds for Success” program assist in 

funding these activities.

Seedling Planting: Seedlings from these trees have a fairly low survival rate ranging from less than 30 to approximately 

70 percent. Seedlings should be planted in the autumn, to avoid summer drought stress, at approximately 200-250 

seedlings per acre with the goal to have a 3 to 5 year survival of 85-100 trees per acre. There should be no overstory 

competition within 20 feet. The planting design should be a patchy pattern with densities similar to that of nearby 

stands. Microsite placement is critical. The transplants should be placed in a protected microsite in moist to the touch 

soil on the north side of a log, rock, or stump. Gophers feed on roots and bury trees, so avoid planting the seedlings in 

areas of deep soils and swales where they burrow. Competing vegetation such as grasses and sedges should be removed 

from the immediate vicinity of the planted seedling. Avoid planting seedlings within 2 feet of bear grass (Xerophyllum 

tenax). On more mesic sites, grouse whortleberry (Vaccinium scoparium Leib. ex Coville) appears to be beneficial to 

establishment when growing in association with whitebark pine and should be retained. Lower elevation xeric sites may 

not have these vegetative components. Current recommendations for planting with WPBR resistant seedlings include, 

1 - sites where WPBR mortality exceeds 20 percent and, 2 - WPBR infection is more than 50 percent.

Pheromone Usage: Pheromones, especially verbenone, can be used to protect against MPB attack. Recent work in 

Idaho on whitebark pine shows a 20 percent increase in survival over a control population when verbenone is used. 

Because of costs, this use is only feasible in high value recreation/visitor areas or on trees either tentatively or positively 

identified as plus trees.

Insecticide Usage: Carbaryl is commonly used to provide protection from MPB. This insecticide when properly applied 

by spraying can provide almost 100 percent protection from MPB attack for up to 2 years. Trees must be accessible to 

compressor driven spray equipment, limiting this application to trees in close proximity to roads.

Pruning: Pruning can be used to extend the life of a five needle pine. Pruning should be done by hand, leaving the 

branch collar (swollen base of the limb) intact. This should only be used on limbs where the WPBR canker is more than 

4 inches from the bole (trunk) of the tree. Because pruning is labor intensive it should only be used to: 1 - to protect 

high value individual trees in high visibility sites such as recreational/ski areas or, 2 - in a small isolated stand with few 

cone bearing trees and no existing seed source for regeneration. Pruning will not change the WPBR resistance of an 

individual tree or stand, but will extend the life span and potential reproductive life of the tree.

Range Management Applications: The historic bison range in Wyoming closely approximates the range of lower 

treeline limber pine in Wyoming. The Nature Conservancy along the Front Range has used the following range 

management technique to replicate bison/limber pine interactions with success. Where feasible, this technique can be 

used on Wyoming BLM lands.

Place water developments and salt stations in close proximity to limber pine stands. This will provide thermal cover 

for livestock. Their usage of the limber pine stands will raise the crown heights due to rubbing, reduce ground cover 

including tree reproduction, and reduce flammable fuels within the stand. The long term objective (50 + year) is to 

approximate an open limber pine stand that resembles historic bison/limber pine interactions.

Wildland Fire Management: Wildland fire has been an integral component of the five needle pine ecosystem. At 

high elevations, low to moderate intensity fires reduce competing vegetation and reduce fuel loadings. Small areas of 

high intensity fires create open areas for Clark’s nutcracker seed caching activities and therefore create areas where 

whitebark pine can regenerate naturally. However, when subalpine fir has expanded extensively into, and provides 

a closed canopy fuel load below them, these stands can burn large areas of five needle pine habitat and reduce or 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 67

eliminate the available seed source. The potential for natural reseeding of these stands via the Clark’s nutcracker is 

subsequently reduced. Some researchers have found a 40 year lag time between fire and the re-establishment of 

whitebark pine on these high elevation areas.

Less is known about the wildland fire effects on the lower elevation five needle pines: Information available suggests 

fire return intervals ranging from 100 to 1,000 years and most fires were probably low to moderate intensity.

At high elevations wildland fire should be allowed to play a role in maintaining these high elevation five needle pine 

ecosystems. A combination of mechanical thinning and prescribed fire can also be used to create the patchy mixed 

severity fire effects in these stands, replicating natural fires. Altering the mixed conifer stands below these high 

elevation stands may be necessary to break up and reduce the canopy cover by creating patches of younger aged (less

flammable stands), and reducing the basal area/SDI of the mature mixed conifer stands to reduce fire behavior before 

it burns into the high elevation stands. Because many of the Wyoming BLM high elevation whitebark and limber pine 

exist in small isolated stands, careful evaluation of fire potential must be done to ensure that these disjunct stands are 

not eliminated from the landscape.

At lower elevations, prescribed and wildland fire can be used at low to moderate intensities to reduce accumulated 

fuels and thin the stands. The best description of this is to “take some and leave some,” so that the stand can remain 

on the landscape and provide for gene conservation and ecosystem services.

General Silvicultural Information for Five Needle Pine Stands: Whitebark and limber pine occur over a range 

of ecological gradients and vegetative associations. This enables the forester to select from a variety of silvicultural 

prescriptions that will meet desired goals for the management of these species. It is important to remember that both 

species of five needle pines are very slow growing, often requiring 50 or more years to reach maturity and produce a 

cone crop. Small size is a poor indicator of recent establishment.

The five needle pines generally do not show strong apical dominance. Because of this, different types of thinning 

around these trees can influence their growth form. Thinning on all four sides will encourage a more spread out, 

multi-forked tree, while thinning on two or three sides will encourage a straighter less forked tree. In mixed stands 

thinning on two or three sides would encourage the tree to have a straighter, taller growth form to allow it to get 

higher in the canopy and access more light for growth. In more open monoculture stands thinning around all four 

sides of either single or multi-stemmed trees would encourage a more open branching crown, increasing cone 

production.

The 5 needle pines, especially the whitebark pine, evolved in a mutualistic relationship with Clark’s nutcracker. The 

whitebark pine and to a lesser extent limber pine require the Clark’s nutcracker to disperse their seed. Research has 

indicated that the nutcracker prefers areas with a minimum basal area of 22 ft2, and a cone production of 

approximately 285 per acre. In areas with a BA of less than 22 ft2, or a production of less than 120 cones 

per acre, there is a rapid decline in the frequency of the nutcracker, until at less than 53 cones per acre; 

Clark’s nutcracker activity becomes negligible. This results in a significant decline in the probability of seed 

dispersal. The current scientific recommendation is that a threshold of approximately 400 cones per acre is 

needed for a high probability of nutcracker presence for seed dispersal.

Important factors in any silvicultural practice are the identification of potential WPBR resistant trees and building the 

on-site prescription around them. Individual stands also vary in their resistance to WPBR due to local genetic material. 

WPBR often takes 25-35 years to kill a mature tree and but only 5 years to kill a sapling. WPBR severely reduces cone 

crop production, often eliminating a living tree from the reproductive pool by killing the cone producing limbs long 

before the tree actually dies.
68 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

When undertaking thinning operations in five needle pines that have white pine blister rust infections, take 

the most heavily infected trees while retaining those trees showing no sign of infection or minor infections 

on limbs that are away from the bole of the tree. Many trees that have a level of rust resistance will have 

a low level of infection on one or more limbs, but show little movement towards the bole of the tree. 

Removing all trees that have minor infections can take partially rust resistant trees out of the genetic pool, 

reducing future stand resistance.

These five needle pines are among the least resistant to the MPB, so often the best strategy may be to manage them 

to reduce the mortality risk. Research has indicated that whitebark pine stands need to have their basal area be below 

45 ft2 to be at least partially resistant to Mountain pine beetle. Thinning to reduce the potential for widespread MPB 

mortality also has the advantage of reducing the competition among the remaining trees and increasing resource 

availability. Field observations have documented MPB attacking 3” to 5” diameter trees.

In cases of severe MPB infestations, it may be necessary not only to remove of all infested five needle pines but also 

any mature uninfected overstory to reduce the MPB habitat (larger diameter trees) and reduce the numbers of MPB 

surviving on site. This may be the only way to protect the advanced reproduction so that the reproduction survives on 

site to provide for future trees and seed source. This will reduce the Basal Area (BA) and/or Stand Density Index (SDI) 

below the guidelines in the specific silvicultural operations described below.

Elevational Differences: Limber pine grows across the widest elevational range of any conifer in the Rocky 

Mountains, ranging from approximately 5,250 feet (1600 m) to almost 11,000 feet (3300 m). The 8,500 foot elevation 

was selected as the dividing point between high elevation/upper treeline and low elevation/lower treeline limber pine 

because of its usage in the only peer reviewed document that established elevational differences in limber pine as a 

research criteria. It is possible that stands meeting the meaning of “high elevation/upper tree line,” i.e. subalpine ridge 

and mountain tops can be found below 8,500 feet and expert field opinion must be used to determine which category 

best fits the stand. Whitebark pine generally grows above 8,000 feet in elevation, but potentially can be found at lower 

elevations. All guidelines for whitebark pine should be used without regard to actual elevation of the stand but rather, 

the associated species.

Specific Silvicultural Operations, Treatments and Prescriptions for Five Needle Pine Stands:

Stand Type: High elevation/upper treeline predominately whitebark and limber pine stands (Generally found above 

8,500 ft. in the subalpine zone).

Desired Conditions/Functions: Maintain and/or restore these stands on the landscape to fill their hydrologic, wildlife 

and other related ecosystem services. Stand structure will be as resistant as possible to MPB infestations. Maintain 

WPBR resistant individuals on site and use their seed source for interplanting to maintain five needle pine stands.

Existing Conditions: These stands are severely impacted by both WPBR and MPB. They are also being encroached on 

by mixed conifer species, especially subalpine fir. These stands range from patchy open woodlands to a more closed 

canopy structure.

Silvicultural Treatments/Prescriptions:

1. Removal of subalpine fir from the stand to reduce competition for resources. If it is not possible to remove all 

the subalpine fir, remove the fir in a radius of 20 feet around large five needle pines (or clumps) and remove fir in a 

radius of at least 10 feet from seedling/sapling five needle pines. Because the five needle pines are very slow growing, 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 69

evidence of release may not be exhibited for five (5) plus years. The relative densities should range between 10 and 25 

percent of the maximum SDI for newly treated stands and should not exceed 40 percent maximum SDI.

2. Thin stands to make them more resistant to MPB attacks in areas with incipient MPB infestation or threat, reduce 

the Basal Area of the trees to less than 45 ft2 but no lower than a Basal Area of 22 ft2. Slash must be disposed 

of by burning within 1 year or less or by mastication to eliminate the risk of pine beetles currently in the removed 

trees to survive in the slash. In areas infected with WPBR preferentially thin the trees exhibiting the greatest amount 

of infection. Attempt to leave different ages and sizes of trees within the stand, but, dependent on proximity 

to MPB, preferentially leave five needle pine trees of less than 6 inches DBH. The relative densities should range 

between 10 and 25 percent of the maximum SDI for newly treated stands and should not exceed 40 percent of 

maximum SDI.

3. Use prescribed fire and natural ignitions where feasible at low to moderate intensities to create openings in the 

stands for Clark’s nutcracker seed caching, to reduce competition from other conifers and to reduce fuel loadings. 

Ensure that small disjunct stands are protected from high intensity crown fire to prevent their elimination form the 

landscape when feasible.

4. Identify, monitor, and collect seeds from potential “plus” trees to provide for a future seed source.

5. Use locally collected seed from “plus” trees to inter-plant these stands when WPBR reaches the break points 

listed above in Seedling Planting section above and there is an absence of uninfected advanced regeneration in the 

understory.

Stand Type: Mixed conifer stands with a five needle pine component (Generally found above 8,500 ft. and directly 

below the subalpine zone):

Desired Conditions/Functions: Maintain five needle pine component in the mixed conifer systems. Maintain an 

appropriate mix of species to maximize whitebark pine seed caching by squirrels for grizzly bear food source. Pine 

species (lodgepole and five needle pine) densities are low enough to minimize MPB epidemics and keep MPB at 

endemic levels. Maintain WPBR resistant individuals on site and use their seed source for in-planting to maintain five 

needle pine stands.

Existing Conditions: These stands are characterized by multiple tree species including lodgepole pine, Engelmann 

spruce, and subalpine fir and the five needle pines. New, unpublished research presented at the High 5 Symposium in 

2010 shows a positive symbiotic relationship between the red squirrel, lodgepole pine, five needle pines, and grizzly 

bears in Canada and the Yellowstone area.

Silvicultural Treatments/Prescriptions:

1. When working in these stands, reduce the five needle pine Basal Area to approximately 25 ft2 (but no lower than 

22 ft2) and reduce the lodgepole pine Basal Area to approximately 30-40 ft2. Preferentially remove the spruce and fir 

to accomplish other vegetative management objectives. The reduction of pine (five needle and lodgepole) Basal Area to 

the 55-65 ft2 range will inhibit the spread of MPB. The relative densities should range between 15 and 25 percent of 

the maximum SDI for newly treated stands and should not exceed 40 percent of the maximum SDI to inhibit the spread 

of MPB.

2. Remove competing woody vegetation around existing five needle pines to provide for release.
70 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

3. Identify, monitor and collect seeds from potential “plus” trees to provide for a future seed source.

4. Use locally collected seed from “plus” trees to interplant these stands when WPBR reaches the break points listed 

above in Seedling Planting section above.

5. Most of these stands have a long fire return intervals [sic] that are a mixed severity to stand replacement types [sic].

Prescribed fire should be targeted to those areas (south facing slopes, lower elevations) where the vegetation indicates 

a mixed severity shorter fire return interval. North facing mesic sites with a crown replacement fire regime should only 

be spot treated (i.e. removal of slash accumulations/piles) and small openings created in the overstory.

Stand Type: Limber pine growing in association with ponderosa pine and/or Douglas fir, aspen, and mountain shrub 

(Generally found below 8,500 ft. /lower treeline.)

Desired Conditions/Functions: Maintain healthy forest conditions with an appropriate limber pine component to 

fulfill ecosystem services and to provide a seed source for post disturbance early seral limber pine establishment to 

serve as a nurse plant and to provide ecological modification of the site to allow for other species to re-establish.

Existing Conditions: In many cases the limber pine in these stands is an early seral species and will be outcompeted 

by the ponderosa pine and Douglas fir. Limber pine serves an important function in these landscapes as a nurse tree 

species and as a site modifier to enable other species to establish. MPB is the primary agent of limber pine mortality in 

these stands.

Silvicultural Treatments/Prescriptions:

1. Thin stands to make them more resistant to MPB attacks. Reduce Basal Area in pine dominated stands to less than 

60 ft2. Leave a scattering of limber pine in the understory to provide for a seed and genetic source. Emphasize limber 

pine on exposed slopes and ridges. Maintain maximum SDI of between 25 and 40 percent.

2. In Douglas fir dominated sites, keep some residual limber pine on site for a seed and genetic source after a 

disturbance. Maintain maximum SDI of between 25 and 40 percent (total SDI for all species).

3. In aspen stands where there is a viable limber pine stand in close proximity to the aspen stand, it is permissible 

to remove the limber pine from the aspen stand as part of an aspen regeneration/wildlife project. Limber pine that 

predates the establishment of the aspen stand should be retained for diversity.

4. Limber pine grows in association with mountain shrubs, often being a nurse tree for the mountain shrub 

community. When needed, thin the limber pine to a tree crown cover of approximately five percent (or a five to 

ten percent of the maximum SDI) to allow the tree to remain on site to provide for a seed and genetic source while 

opening up the stand to encourage mountain shrub production. Leave multi-age cohorts on site wherever feasible.

5. Identify, monitor and collect seeds from potential “plus” trees to provide for a future seed source.

6. Use locally collected seed from “plus” trees to inter-plant these stands when WPBR reaches the break points listed 

above in Seedling Planting section above.

7. Prescribed fire can be used in these stands. Primary objectives of prescribed fire will often be reduction of fuels 

and re-introducing fire for the benefit of other later seral woody species. Low to moderate intensity fire will assist in 

maintaining limber pine on site, and should not be directed at limber pine stand eradication.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 71

Stand Type: Limber pine stands growing in riparian areas (Generally found below 8,500 ft.).

Desired Conditions/Functions: Restore or maintain a fully functioning riparian/wetland area as measured by Proper 

Functioning Condition (PFC, and/or other site specific resource objectives).

Existing Conditions: In some riparian/wetland areas there has been an expansion of upland vegetation including 

limber pine, Douglas fir, juniper, and sagebrush into these systems. This expansion is detrimental to the functions of 

the riparian/wetland areas as determined by the Standards for Healthy Rangeland (WY BLM). Limber pine in these 

areas tends to be faster growing than in upland areas and can impact, in conjunction with the other upland species, 

the functioning conditions of riparian/wetland areas. Impacts from MPB and WPBR vary widely in these stands, ranging 

from areas of very high mortality to stands that are just beginning to be impacted. Future outlook is for increasing MPB 

mortality and increasing WPBR infection/mortality as well as continued expansion into the riparian/wetland areas.

Silvicultural Treatments/Prescriptions:

1. Limber pine does play a significant role in the hydrology of the watershed. It should be left on the landscape in 

the upland areas away from the riparian zone. Management of these upland stands should follow the silvicultural 

treatments and prescriptions in the stand type “Lower treeline limber pine stands either in association with juniper 

species or a monoculture” described below.

2. In areas where PFC or other monitoring studies, assessments, or evaluations indicate: 1 - an excess of upland 

vegetation exists in the riparian/wetland area, and 2 - conifer expansion is identified as one of the casual [sic] factors 

affecting the functionality of the system, it is permissible to remove limber pine. The removal of some limber pine and 

other upland vegetation within the riparian/wetland system will assist in meeting or making progress towards meeting 

the Standards for Healthy Rangelands (BLM, Wyoming), and/or other site specific objectives. Because the ecology 

of limber pine is not fully understood, a “leave some take some” approach should be implemented in the riparian/

wetland zones as in upland areas.

Stand Type: Lower treeline limber pine stands either in association with juniper species or a monoculture (Generally 

found below 8,500 ft. in ecotones).

Desired Conditions/Functions: Preserve and maintain these stands on the landscape as woodlands and savannas, 

with density levels commensurate with reduced risk of widespread MPB mortality. Allow these stands the flexibility to 

move on the landscape in response to changing climatic and other environmental conditions.

Existing conditions: There has been a lack of research on these stands, and very little is known about the ecosystem 

services provided. These often occur on steeper, rocky, exposed slopes and have shown movement downslope in the 

past 100-200 years. MPB is found in these stands at increasing levels of infestation and mortality. WPBR infections and 

MPB infestations vary widely in these stands, ranging from areas of very high mortality from one or both WPBR and 

MPB to stands that are just beginning to be impacted. Future outlook is for increasing MPB mortality and increasing 

WPBR infection/mortality.

Silvicultural Treatments/Prescriptions:

1. Thin stands to make them more resistant to MPB attacks. Stands should be thinned to a Basal Area of 40-45 ft2

where they form a fairly continuous canopy cover. Preferentially remove juniper species (Utah and Rocky Mountain) to 

allow for release and to open up the understory for grass and forb establishment and growth. Maintain Maximum SDI 

of between 25 and 40 percent.
72 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

2. On deeper soils at the bottom of slopes and drainages, when needed, thin the limber pine to a tree crown cover 

of approximately five percent (or a five to ten percent of the maximum SDI) to allow the tree to remain on site as an 

open woodland and to provide for a seed and genetic source. If maintenance of a higher density woodland is desired, 

maintain Maximum SDI of between 25 and 40 percent. Leave multi-age cohorts on site wherever feasible.

3. Use the Range Management Application described above to assist in creating an open woodland stand of 

limber pine.

4. Identify, monitor and collect seeds from potential “plus” trees to provide for a future seed source.

5. Use locally collected seed from “plus” trees to inter-plant these stands when WPBR reaches the break points listed 

above in Seedling Planting section above.

6. Use low to moderate intensity prescribed and natural fire to assist in thinning of the stands. The best description 

of this is to “take some and leave some,” so that the stand can remain on the landscape and provide for gene 

conservation and ecosystem services.

Stand Type: Lower treeline limber pine stands growing in sagebrush areas such as former sagebrush meadows and 

otherwise suitable sage-grouse habitat (Found below 8,500 ft. in ecotones).

Desired Conditions/Functions: Restore open sagebrush flats and meadows for suitable sage-grouse habitats and to 

protect important habitats from extreme fire behavior.

Existing Conditions: In some transitional sagebrush areas there has been observed expansion, and in some cases 

invasion, of coniferous vegetation including limber pine and juniper into habitats managed for Sage-grouse. This noted 

expansion is detrimental to the overall functionality of important Sage-grouse habitats as measured by the Habitat 

Assessment Framework and associated Standards for Healthy Rangeland (WY BLM). The expansion of Limber pine 

and other coniferous species in these areas may increase risk for high severity wildland fire and threaten reduction of 

important Sage-grouse habitat functionality.

Silvicultural Treatments/Prescriptions:

1. Conifer removal efforts must consider and observe the concurrent goals and objectives of the sensitive species of 

limber pine management and maintain adjacent limber pine sites for local seed source. Projects would be conducted 

following the silvicultural treatment prescriptions in the stand type “Lower treeline limber pine stands (below 8,500 ft.) 

either in association with juniper species or a monoculture” described above.

2. In areas where long-term sagebrush steppe and sage-grouse habitat management objectives would require removal 

of encroaching conifer species, including limber pine, it is permissible to remove conifers from important sagebrush 

steppe habitats in an effort to support maintain and improve conservation of habitat for Sage-grouse and other 

sagebrush obligate species.

Stand Type: Limber pine stands growing in surface disturbance areas such as rock/gravel quarries and other mining 

activity (Generally found below 8,500 ft., but can occur at other elevations dependent on mineral locations).

Desired Conditions/Functions: Reclamation of disturbed limber pine sites including the planting of limber pine 

seedlings using local seed source and other mitigation methods determined to be acceptable.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 73

Existing Conditions: The development of surface disturbing activities can eliminate all or portions of limber pine 

stands. These activities may occur in any of the limber pine types, but will be concentrated in the “Limber pine growing 

in association with ponderosa pine and/or Douglas fir, aspen, and mountain shrub” and the “Lower treeline limber 

pine stands either in association with juniper species or a monoculture” types. MPB and WPBR vary widely in these 

stands, ranging from areas of very high mortality from one or both WPBR and MPB to stands that are just beginning to 

be impacted. Future outlook is for increasing MPB mortality and increasing WPBR infection/mortality.

Silvicultural Treatments/Prescriptions:

1. Limber pine within the project boundaries that are not in the disturbed area will be managed as per the appropriate 

sivlicultural [sic] treatments/prescriptions listed above as partial mitigation of the disturbance.

2. Disturbed areas will be planted with local seed source seedlings from project area or adjacent stands as per the 

seedling planting guidelines.

3. If an entire stand is within the disturbance area, off-site mitigation in the form of appropriate silvicultural treatments 

of adjacent stands, collection of seed, identification of “plus” trees or other acceptable mitigations will be done to 

offset the loss of a stand in addition to replanting limber pine on the reclaimed area.
Photo provided by the National Park Service, U.S.D.I., Public Domain
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 75

References

Amman, G.D. 1973. Population changes of the mountain pine beetle in 

relation to elevation. Environmental Entomology 2 (4): 541–48.

Amman, G.D., and W.E. Cole. 1983. Mountain pine beetle dynamics in 

lodgepole pine forests. Part II: Population dynamics USDA Forest 

Service, Intermountain Forest and Range Experiment Station, 

Gen. Tech. Rep. GTR-INT-145, Ogden, UT.

Anderson, B.J., H.R. Akçakaya, M.B. Araújo, D.A. Fordham, E. MartinezMeyer, W. Thuiller, and B.W. Brook. 2009. Dynamics of range 

margins for metapopulations under climate change. Proceedings 

of the Royal Society B 276:1415–20.

Arno, S.F. 1980. Forest fire history in the Northern Rockies Journal of 

Forestry 78:460–65.

Arno, S.F. 1986. Whitebark pine cone crops: A diminishing source of 

wildlife food. Western Journal of Applied Forestry 9:92–94.

Arno, S.F., and R.J. Hoff. 1989. Silvics of whitebark pine (Pinus 

albicaulis). USDA Forest Service, Intermountain Research Station, 

Gen. Tech. Rep. GTR-INT-253, Ogden, UT. 

———. 1990. Pinus albicaulis Engelm. In Whitebark pine. Silvics 

of North America, conifers, 268–79. USDA Forest Service, 

Agricultural Handbook 654, Washington, DC. 

Arno, S.F., E.D. Reinhardt, and J.H. Scott. 1993. Forest structure and 

landscape patterns in the subalpine lodgepole pine type: A 

procedure for quantifying past and present conditions. USDA 

Forest Service, Intermountain Research Station, Gen. Tech. Rep. 

INT-294, Ogden, UT.

Arno, S.F., and T. Weaver. 1990. Whitebark pine community types and 

their patterns on the landscape. In Proceedings—Symposium 

on whitebark pine ecosystems: Ecology and management of a 

high-mountain resource, comp. W.C. Schmidt and K.J. McDonald, 

97–105. USDA Forest Service, Intermountain Research Station, 

Gen. Tech. Rep. INT-270, Ogden, UT. 
76 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Aubry, C., D. Goheen, R. Shoal, T. Ohlson, T. Lorenz, A. Bower, C. Mehmel, and R.A. Sniezko. 2008. Whitebark 

pine restoration strategy for the Pacific Northwest Region 2009–2013. USDA Forest Service, Pacific 

Northwest Region, Region 6 Report, Portland, OR.

Baker, B.H., G.D. Amman, and G.C. Trostle. 1971. Does the mountain pine beetle change hosts in mixed 

lodgepole and whitebark pine stands? USDA Forest Service, Intermountain Forest and Range Experiment 

Station, Research Note INT-151, Ogden, UT. 

Barringer, L.E., D.F. Tomback, M.B. Wunder, and S.T. McKinney. 2012. Whitebark pine stand condition, tree 

abundance, and cone production as predictors of visitation by Clark’s nutcracker. PLoS ONE 7 (5): 

e37663. 

Bentz, B.J. 2000. Forest Insect and Disease Tally System (FINDIT) user manual. USDA Forest Service, Rocky 

Mountain Research Station, Gen. Tech. Rep. RMRS-GTR-49, Fort Collins, CO. 

Bentz, B.J., S. Kegley, K. Gibson, and R. Thier. 2005. A test of high-dose verbenone for stand-level protection 

of lodgepole and whitebark pine from mountain pine beetle (Coleoptera: Curculionidae: Scolytinae) 

attacks. Journal of Economic Entomology 98 (5): 1614–21.

Bentz, B.J., J.A. Logan, and G.D. Amman. 1991. Temperature-dependent development of the mountain 

pine beetle (Coleoptera: Scolytidae) and simulation of its phenology. Canadian Entomologist 123 (5): 

1083–94.

Bentz, B.J., J. Regniere, C.J. Fettig, E.M. Hansen, J.L. Hayes, J.A. Hicke, R.G. Kelsey, J.F. Negron, and 

S.J. Seybold. 2010. Climate change and bark beetles of the western United States and Canada: Direct 

and indirect effects. BioScience 60 (8): 602–13.

Bentz, B.J., J. Vandygriff, C. Jensen, T. Coleman, P. Maloney, S. Smith, A. Grady, and G. Schen-Langenheim. 

2014. Mountain pine beetle voltinism and life history characteristics across latitudinal and elevational 

gradients in the western United States. Forest Science 60 (3): 434–49. 

Bingham, R.T., R.J. Hoff, and G.I. McDonald, coords. 1972. Biology of rust resistance in forest trees: 

Proceedings of a NATO-IUFRO Advanced Study Institute, 271–78. USDA Forest Service, Misc. Publ. 1221, 

Washington, DC. http://www.treesearch.fs.fed.us/pubs/35041

Bower, A.D., and S.N. Aitken. 2008. Ecological genetics and seed transfer guidelines for Pinus albicaulis

(Pinaceae). American Journal of Botany 95:66–76.

Boyce, J.S. 1961. Forest pathology. New York: McGraw-Hill. 

Brown, D.H. 1969. Aerial application of antibiotic solutions to whitebark pine infected with Cronartium 

ribicola. Plant Disease Reporter 53:487–89.

Bruederle, L.P., D.P. Rogers, K.V. Krutovskii, and D.V. Politov. 2001. Population genetics and evolutionary 

implications. In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and 

R.E. Keane, 137–58. Washington, DC: Island Press. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 77

Bureau of Land Management (BLM). 2012. Final Memorandum 11-3-C, Middle Rockies rapid ecoregional 

assessment.

———. 2015. National Native Seed Strategy for Rehabilitation and Restoration, 2015–2020. 

http://www.blm.gov/ut/st/en/prog/more/CPNPP/0/seedstrategy.html

Burns, K.S., A.W. Schoettle, W.R. Jacobi, and M.F. Mahalovich. 2007. White pine blister rust in the Rocky 

Mountain region and options for management. USDA Forest Service, Rocky Mountain Region, Biological 

Evaluation R2-07-04, Golden, CO. 

———. 2008. Options for the management of white pine blister rust in the Rocky Mountain region. USDA 

Forest Service, Rocky Mountain Research Station, Report RMRS-GTR-206, Fort Collins, CO.

Burr, K.E., A. Eramian, and K. Eggleson. 2001. Growing whitebark pine seedlings for restoration. 

In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.A. Arno, and R.E. Keane, 

325–46. Washington, DC: Island Press. 

Callaway, R.M. 1998. Competition and facilitation on elevation gradients in subalpine forests of the northern 

Rocky Mountains, USA. Oikos 82 (3): 561–73.

Callaway, R.M., A. Sala, and R.E. Keane. 1998. Replacement of whitebark pine by subalpine fir: The 

consequences for stand carbon, water, and nitrogen cycles. USDA Forest Service, Fire Sciences 

Laboratory, Final Report RJVA-INT-95086, Missoula, MT. 

Campbell, E.M. 1998. Whitebark pine forests in British Columbia: Composition, dynamics and the effects of 

blister rust. Victoria, British Columbia: Univ. of Victoria.

Campbell E.M., and J.A. Antos. 2000. Distribution and severity of white pine blister rust and mountain pine 

beetle on whitebark pine in British Columbia. Canadian Journal of Forest Research 30:1051–59.

Campbell, E.M., R.E. Keane, E. Larson, M.P. Murray, A.W. Schoettle, and C. Wong. 2011. Disturbance ecology 

of high-elevation five-needle pine ecosystems in western North America. In The future of high-elevation, 

five-needle white pines in western North America: Proceedings of the High Five Symposium, 28–30 June 

2010, Missoula, MT, ed. R.E. Keane, D.F. Tomback, M.P. Murray, and C.M. Smith, 154–63. USDA Forest 

Service, Rocky Mountain Research Station Proceedings RMRS-P-63, Fort Collins, CO. 

Charlet, D.A. 1996. Atlas of Nevada conifers: A phytogeographic reference. Reno, NV: Univ. of Nevada Press.

Ciesla, W.M., and M.M. Furniss. 1975. Idaho’s haunted forests. American Forests 81 (8): 32–35.

Cole, W.E., and G.D. Amman. 1980. Mountain pine beetle dynamics in lodgepole pine forests. Part 1: Course 

of an infestation. USDA Forest Service, Gen. Tech. Rep. INT-89, Ogden, UT.

Creeden, E.P., J.A. Hicke, and P.C. Buotte. 2014. Climate, weather, and recent mountain pine beetle outbreaks 

in the western United States. Forest Ecology and Management 312:239–51.
78 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Crone, E.E., E.J.B. McIntire, and J. Brodie. 2011. What defines mast seeding? Spatio-temporal patterns of cone 

production by whitebark pine. Journal of Ecology 99(2): 438–44. 

Dale, V.H., L.A. Joyce, S. McNulty, R.P. Neilson, M.P. Ayres, and M.D. Flannigan. 2001. Climate change and 

forest disturbances. BioScience 51 (9): 723–34. 

Dale, V.H., M.L. Tharp, K.O. Lannom, and D.G. Hodges. 2010. Modeling transient response of forests to 

climate change. Science of the Total Environment 408 (2010): 1888–1901.

Daly, C., D.R. Conklin, and M.H. Unsworth. 2009. Local atmospheric decoupling in complex topography alters 

climate change impacts. International Journal of Climatology 30 (12): 1857–64.

Davies, M.A., and M. Murray. 2006. Tree tong puts whitebark pine cones within reach. USDA Forest Service, 

Technology and Development Program Tech Tip 0624–2354–MTDC, Missoula, MT.

DeMastus, C.R. 2013. Effective methods of regenerating whitebark pine (Pinus albicaulis) through direct 

seeding. Master’s thesis, Montana State Univ. 

Elderd, B.D., J. Dushoff, and G. Dwyer. 2008. Host-pathogen interactions, insect outbreaks, and natural 

selection for disease resistance. The American Naturalist 172 (6): 829–42.

Faccoli, M., and F. Schlyter. 2007. Conifer phenolic resistance markers are bark beetle antifeedant 

semiochemicals. Agriculture and Forest Entomology 9 (3): 237–45. 

Farnes, P.E. 1990. SNOTEL and snow course data: Describing the hydrology of whitebark pine ecosystems. 

In Proceedings – Symposium on whitebark pine ecosystems: Ecology and management of a highmountain resource, comp. W.C. Schmidt and K.J. McDonald, 302–4. USDA Forest Service, Intermountain 

Research Station, Gen. Tech. Rep. INT-270, Ogden, UT.

Federal Register. 2011. Endangered and threatened wildlife and plants: 12-month finding on a petition to list 

Pinus albicaulis as endangered or threatened with critical habitat; A proposed rule by the U.S. Fish and 

Wildlife Service on 7/19/2011. Federal Register 76 (138): 42631–54.

Ferrenberg, S., J.M. Kane, and J.B. Mitton. 2014. Resin duct characteristics associated with tree resistance to 

bark beetles across lodgepole and limber pines. Oecologia 174 (4): 1283–92.

Fettig, C.J., B.M. Bulaon, C.P. Dabney, C.J. Hayes, and S.R. McKelvey. 2012. Verbenone plus reduces levels 

of tree mortality attributed to mountain pine beetle infestations in whitebark pine, a tree species of 

concern. Journal of Biofertilizers and Biopesticides 3 (4): 1–5.

Fins, L., J. Byler, D. Freguson, A. Harvey, M.F. Mahalovich, G.I. McDonald, D. Miller, J. Schwandt, and A. Zack. 

2001. Return of the giants: Restoring white pine ecosystems by breeding and aggressive planting of 

blister rust-resistant white pines. University of Idaho Station Bulletin 72:1–22.

Flannigan, M., B. Stocks, M. Turetsky, and M. Wotton. 2008. Impacts of climate change on fire activity and 

fire management in the circumboreal forest. Global Change Biology 14:1–12. doi: 10.1111/j.1365-

2486.2008.01660.x.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 79

Forcella, F. 1978. Flora and chorology of the Pinus albicaulis - Vaccinium scoparium association. Madroño 

25:139–50.

Forcella, F, and T. Weaver. 1977. Biomass and productivity of subalpine Pinus albicaulis- Vaccinium scoparium

association in Montana, USA. Vegetatio 35:95–105.

Forcella, F., and T. Weaver. 1980. Food production in the Pinus albicaulis - Vaccinium scoparium association. 

Proceedings of the Montana Academy of Science 39:73–80.

Frankham, R., J.D. Ballou, and D.A. Briscoe. 2002. Introduction to Conservation Genetics. Cambridge: 

Cambridge University Press. 

Furnier, G.R., P. Knowles, M.A. Clyde, and B.P Dancik. 1987. Effects of avian seed dispersal on the genetic 

structure of whitebark pine populations. Evolution 41:607–12.

Furniss, R.L., and V.M. Carolin. 1977. Western Forest Insects. USDA Forest Service, Misc. Publ. 1339, 

Washington, DC.

Geils, B.W., K.E. Hummer, and R.S. Hunt. 2010. White pines, ribes, and blister rust: A review and synthesis. 

Forest Pathology 40 (3/4): 147–85.

Gernandt, D.S., G.G. López, S.O. Garcia, and A. Liston. 2005. Phylogeny and classification of Pinus. Taxon 

54:29–42.

Gibson, K., K. Skov, S. Kegley, C. Jorgensen, S. Smith, and J. Witcosky. 2008. Mountain pine beetle impacts 

in high-elevation five-needle pines: Current trends and challenges. USDA Forest Service, Forest Health 

Protection Report R1-08-020, Missoula, MT. 

Gillette, N.E., E.M. Hansen, C.J. Mehmel, S.R. Mori, J.N. Webster, N. Erbilgin, and D.L. Wood. 2012. Areawide application of verbenone-releasing flakes reduces mortality of whitebark pine Pinus albicaulis

caused by the mountain pine beetle Dendroctonus ponderosae. Agricultural and Forest Entomology 

14 (4): 367–75.

Greater Yellowstone Coordinating Committee - Whitebark Pine Subcommittee. 2011. Whitebark pine 

strategy for the Greater Yellowstone Area. USDA Forest Service and USDI National Park Service, West 

Yellowstone, MT.

Greater Yellowstone Whitebark Pine Monitoring Working Group. 2011. Interagency whitebark pine 

monitoring protocol for the Greater Yellowstone ecosystem, vers. 1.1. Greater Yellowstone Coordinating 

Committee, Bozeman, MT.

Greater Yellowstone Whitebark Pine Monitoring Working Group. 2013. Monitoring whitebark pine in the 

Greater Yellowstone ecosystem. 2013 Annual Report. Prepared by E. Shanahan. Natural Resource Data 

Series NPS/GRYN/NRDS—2014/631. National Park Service, Bozeman, MT. 

Hamann, A., and T. Wang. 2006. Potential effects of climate change on ecosystem and tree species distribution 

in British Columbia. Ecology 87 (11): 2773–86.
80 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Hobbs, R.J., and V.A. Cramer. 2008. Restoration ecology: Interventionist approaches for restoring and 

maintaining ecosystem function in the face of rapid environmental change. Annual Review of 

Environment and Resources 33:39–61.

Hoff, R.J. 1986. Inheritance of the bark reaction resistance mechanism in Pinus monticola infected by 

Cronartium ribicola. USDA Forest Service, Intermountain Research Station, Research Note INT-361, 

Ogden, UT.

Hoff, R.J. 1992. How to recognize blister rust infection on whitebark pine. USDA Forest Service, Intermountain 

Research Station, Research Note INT-406, Ogden, UT.

Hoff, R., R.T. Bingham, and G.I. McDonald. 1980. Relative blister rust resistance of white pines. European 

Journal of Forest Pathology 10:307–16.

Hutchins, H.E. 1994. Role of various animals in dispersal and establishment of whitebark pine in the Rocky 

Mountains, USA. USDA Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-GTR-309, 

Ogden, UT.

Hutchins, H.E., and R.M. Lanner. 1982. The central role of Clark’s nutcracker in the dispersal and establishment 

of whitebark pine. Oecologia 55:192–201.

Iglesias, V., T.R. Krause, and C. Whitlock. 2015. Complex response of white pines to past environmental 

variability increases understanding of future vulnerability. PLoS ONE 10 (4): e0124439. 

Izlar, D.K. 2007. Assessment of whitebark pine seedling survival for Rocky Mountain plantings. Master’s thesis, 

College of Forestry and Conservation, Univ. of Montana. 

Jackson, S., and J. Betancourt. N.d. Final report. Late holocene expansion of Utah juniper in Wyoming: 

A modeling system for studying ecology of natural invasions. NSF-DEB-9815500. Publication data 

unavailable. http://wwwpaztcn.wr.usgs.gov/wyoming/NSF_report.pdf

Keane, R.E. 2000. The importance of wilderness to whitebark pine research and management. In Wilderness 

science in a time of change, vol. 3: Wilderness as a place for scientific inquiry, comps. S.F. McCool, D.N. 

Cole, W.T. Borrie, J. O’Loughlin, 84–93. USDA Forest Service, Rocky Mountain Research Station, Gen. 

Tech. Rep. RMRS-P-15-VOL-3, Fort Collins, CO.

Keane, R.E. 2001. Successional dynamics: Modeling and anthropogenic threat. In Whitebark pine communities: 

Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 159–92. Washington, DC: Island 

Press.

Keane, R.E., and S.F. Arno. 1993. Rapid decline of whitebark pine in western Montana: Evidence from 

20-year remeasurements. Western Journal of Applied Forestry 8:44–47.

———. 2001. Restoration concepts and techniques. In Whitebark pine communities: Ecology and restoration, 

ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 367–400. Washington, DC: Island Press.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 81

Keane, R.E., J. Garner, C. Teske, C. Stewart, and P. Hessburg. 2002. Range and variation in landscape patch 

dynamics: Implications for ecosystem management. In Proceedings from the 1999 National Silviculture 

Workshop, 19–26. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.

Keane, R.E., K.L. Gray, and L.J. Dickinson. 2007. Whitebark pine diameter growth response to removal of 

competition. USDA Forest Service, Rocky Mountain Research Station, Research Note RMRS-RN-32, Fort 

Collins, CO. 

Keane, R.E., L.M. Holsinger, M.F. Mahalovich, and D.F. Tomback. In press. Restoring whitebark pine (Pinus 

albicaulis) ecosystems in the face of climate change. USDA Forest Service, Rocky Mountain Research 

Station, preprint, Gen. Tech. Rep. RMRS-GTR-XXX, Fort Collins, CO. 

Keane, R.E., P. Morgan, and J.P. Menakis. 1994. Landscape assessment of the decline of whitebark pine 

(Pinus albicaulis) in the Bob Marshall Wilderness Complex, Montana, USA. Northwest Science 68:213–29.

Keane, R.E., and R.A. Parsons. 2010a. Restoring whitebark pine forests in the northern Rocky Mountains, USA. 

Ecological Restoration 28:56–70.

———. 2010b. Management guide to ecosystem restoration treatments: Whitebark pine forests of the 

northern Rocky Mountains, U.S.A. USDA Forest Service, Rocky Mountain Research Station, Gen. Tech. 

Rep. RMRS-GTR-232, Fort Collins, CO.

Keane, R.E., D.F. Tomback, C.A. Aubry, A.D. Bower, E.M. Campbell, C.L. Cripps, M.B. Jenkins, M.F. Mahalovich, 

M. Manning, S.T. McKinney, M.P. Murray, D.L. Perkins, D.P. Reinhart, C. Ryan, A.W. Schoettle, and 

C.M. Smith. 2012. A range-wide restoration strategy for whitebark pine (Pinus albicaulis). USDA Forest 

Service, Rocky Mountain Research Station, Gen. Tech. Rep. RMRS-GTR-279, Fort Collins, CO.

Keane, R.E., D.F. Tomback, M.P. Murray, and C.M. Smith, eds. 2011. The future of high-elevation, five-needle 

white pines in western North America: Proceedings of the High Five Symposium, 28–30 June 2010, 

Missoula, MT. USDA Forest Service, Rocky Mountain Research Station Proceedings RMRS-P-63, Fort 

Collins, CO. 

Kegley, S., and K. Gibson. 2004. Protecting whitebark pine trees from mountain pine beetle attack using 

verbenone. USDA Forest Service, Northern Region, Forest Health Protection Report 04-8, Missoula, MT. 

———. 2009. Individual-tree tests of verbenone and green-leaf volatiles to protect lodgepole, whitebark and 

ponderosa pines, 2004–2007. USDA Forest Service, Forest Health Protection Report 09-03. 

Kegley, S., K. Gibson, J. Schwandt, and M. Marsden. 2003. A test of verbenone to protect individual whitebark 

pine from mountain pine beetle attack. USDA Forest Service, Forest Health Protection Report 03-9, 

Missoula, MT.

Kendall, K.C. 1995. Whitebark pine: Ecosystem in peril. In Our living resources, ed. E.T. LaRoe, G.S. Farris, 

C.E. Puckett, P.D. Doran, and M.J. Mac, 228–30. U.S. Department of the Interior, National Biological 

Service, Washington, DC.
82 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Kendall, K.C., and R.E. Keane. 2001. Whitebark pine decline: Infection, mortality and population trends. 

In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 

221–42. Washington, DC: Island Press.

King, J.C., and L.J. Graumlich. 1998. Stem-layering and genet longevity in whitebark pine. A final report on 

cooperative research with the National Park Service, CA 8000-2-9001.

Krawchuk, M.A., M.A. Moritz, M.A. Parisien, J. Van Dorn, and K. Hayhoe. 2009. Global pyrogeography: The 

current and future distribution of wildfire. PLoS ONE 4 (4): e5102. 

Krist, F.J., Jr., J.R. Ellenwood, M.E. Woods, A.J. McMahan, J.P. Cowardin, D.E. Ryerson, F.J. Sapio, 

M.O. Zweifler, S.A. Romero. 2014. 2013–2027 National Insect and Disease Forest Risk Assessment. 

USDA Forest Service, Forest Health Technology Enterprise Team, FHTET-14-01, Fort Collins, CO.

Krugman, S.L., and J.L. Jenkinson. 1974. Pinus L. pine. In Seeds of woody plants in the United States, tech. 

coord. C.S. Schopmeyer, 598–638. USDA Forest Service, Agriculture Handbook No. 450, Washington, DC.

Kunkel, K.E., T.R. Karl, D.R. Easterling, K. Redmond, J. Young, X. Yin, and P. Hennon. 2013. Probable maximum 

precipitation (PMP) and climate change. Geophysical Research Letters 40:1402–8. 

LANDFIRE. 2013. LANDFIRE Existing Vegetation Type Layer. U.S. Department of the Interior, U.S. Geological 

Survey (accessed May 8, 2013). http://landfire.cr.usgs.gov/viewer/

Lanner, R.M. 1980. Avian seed dispersal as a factor in the ecology and evolution of limber and whitebark 

pines. Proceedings of the sixth North American forest biology workshop, ed. B.P. Dancik and 

K.O. Higginbotham, 15–48. Edmonton, Alberta, Canada.

———. 1982. Adaptations of whitebark pine for seed dispersal by Clark’s nutcracker. Canadian Journal of 

Forest Research-Revue Canadienne De Recherche Forestiere 12 (2): 391–402.

———. 1996. Made for each other: A symbiosis of birds and pines. Oxford, United Kingdom: Oxford Univ. 

Press.

Lanner, R.M., and B.K. Gilbert. 1994. Nutritive value of whitebark pine seeds and the question of their variable 

dormancy. In Proceedings—International workshop on subalpine stone pines and their environment: 

The status of our knowledge, comp. W.C. Schmidt, and F.K. Holtmeier, 206–11. USDA Forest Service, 

Intermountain Research Station, Gen. Tech. Rep. INT-GTR-309, Ogden, UT.

Larson, E.R., and K.F. Kipfmueller. 2010. Patterns in whitebark pine regeneration and their relationships to 

biophysical site characteristics in southwest Montana, central Idaho, and Oregon, USA. Canadian Journal 

of Forest Research 40 (3): 476–87.

———. 2012. Ecological disaster or the limits of observation? Reconciling modern declines with the long-term 

dynamics of whitebark pine communities. Geography Compass (6/4): 189–214.

Linhart, Y.B., and D.F. Tomback. 1985. Seed dispersal by nutcrackers causes multi-trunk growth form in pines. 

Oecologia 67:107–10. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 83

Littell, J.S. 2011. Impacts in the next few decades and the next century (fire and climate figures 5.6 and 

5.8). In Committee on Stabilization Targets for Atmospheric Greenhouse Gas Concentrations, Climate 

stabilization targets: Emissions, concentrations, and impacts over decades to millennia, 178–80. Division 

on Earth and Life Studies, National Research Council of the National Academies. Washington, DC: The 

National Academies Press. 

Littell, J.S., E.E. Oneil, D. McKenzie, J.A. Hicke, J.A. Lutz, R.A. Norheim, and M.M. Elsner. 2010. Forest 

ecosystems, disturbance, and climatic change in Washington State, USA. Climatic Change 102:129–58. 

Little, E.L., Jr. 1971. Conifers and important hardwoods. Vol. 1 of Atlas of United States Trees. USDA Forest 

Service, Misc. Publ. 1146, Washington, DC. 

Little, E.L., Jr., and W.B. Critchfield. 1969. Subdivisions of the genus Pinus (pines). USDA Forest Service, Misc. 

Publ. 1144, Washington, DC.

Loehman, R.A., A. Corrow, and R.E. Keane. 2011. Modeling climate changes and wildfire interactions: Effects 

on whitebark pine (Pinus albicaulis) and implications for restoration, Glacier National Park, Montana, 

USA. In The future of high-elevation, five-needle white pines in western North America: Proceedings 

of the High Five Symposium, 28–30 June 2010, Missoula, MT, ed. R.E. Keane, D.F. Tomback, M.P. 

Murray, and C.M. Smith, 176–88. USDA Forest Service, Rocky Mountain Research Station Proceedings 

RMRS-P-63, Fort Collins, CO. 

Logan, J.A., and B.J. Bentz. 1999. Model analysis of mountain pine beetle (Coleoptera: Scolytidae) seasonality. 

Environmental Entomology 28 (6): 924–34.

Logan, J.A., and J.A. Powell. 2001. Ghost forests, global warming, and the mountain pine beetle 

(Coleoptera: Scolytidae). American Entomologist 47 (3): 160–73.

Lonergan, E.R., C.L. Cripps, and C.M. Smith. 2014. Influence of site conditions, shelter objects, and 

ectomycorrhizal inoculation on the early survival of whitebark pine seedlings planted in Waterton Lakes 

National Park. Forest Science 60 (3): 603–12.

Long, J.N., and J.D. Shaw. In press. Management of whitebark pine (Pinus albicaulis) stands for resistance and 

resilience. Forest Science.

Lorenz, T. J., C. Aubry, and R. Shoal. 2008. A review of the literature on seed fate in whitebark pine and 

the life history traits of Clark’s Nutcracker and pine squirrels. USDA Forest Service, Pacific Northwest 

Research Station, Gen. Tech. Rep. PNW-GTR-742, Portland, OR.

Lorenz, T.J., and K.A. Sullivan. 2009. Seasonal differences in space use by Clark’s nutcrackers in the Cascade 

Range. The Condor 111 (2): 326–40.

Lorenz, T.J., K.A. Sullivan, A.V. Bakian, and C.A. Aubry. 2011. Cache-site selection in Clark’s nutcracker 

(Nucifraga columbiana). The Auk 128 (2): 237–47.

Luckman, B.H., L.A. Jozsa, and P.J. Murphy. 1984. Living seven-hundred-year-old Picea engelmannii and Pinus 

albicaulis in the Canadian Rockies. Arctic and Alpine Research 16:419–22.
84 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Mahalovich, M.F., K.E. Burr, and D.L. Foushee. 2006. Whitebark pine germination, rust resistance and cold 

hardiness among seed sources in the Inland Northwest: Planting strategies for restoration. In National 

proceedings: Forest and conservation nursery association, tech. coord. L.E. Riley, R.K. Dumroese, and 

T.D. Landis, 91–101. USDA Forest Service, Rocky Mountain Research Station Proceedings RMRS-P-43, Fort 

Collins, CO.

Mahalovich, M.F., and G.A. Dickerson. 2004. Whitebark pine genetic restoration program for the intermountain 

west (United States). In Breeding and genetic resources of five-needle pines: Growth, adaptability and 

pest resistance, ed. R.A. Sniezko, S. Samman, S.E. Schlarbaum, and H.B. Kriebel, 181–87. USDA Forest 

Service, Rocky Mountain Research Station Proceedings RMRS-P-32, Fort Collins, CO.

Mahalovich, M.F., and D.L. Foushee. In press. Pinus albicaulis Engelm. genetic restoration program for the 

inland west (USA): A first generation of improvement. In Challenges and opportunities in (1) genetics 

of five-needle pines and (2) rusts of forest trees research: Conservation, evolution and sustainable 

management in a changing climate, eds. A.W. Schoettle and Sniezko, R.A. 2015. Proceedings of the 

IUFRO Joint Conference 2.02.15 Breeding and Genetic Resources of Five-Needle Pines, 7.02.05 Rusts 

of Forest Trees and Strobusphere, June 15–20, 2014, Fort Collins, CO. USDA Forest Service, Rocky 

Mountain Research Station, Proceedings RMRS-P-XX, Fort Collins, CO. 

Mahalovich, M.F., and V.D. Hipkins. 2011. Molecular genetic variation in whitebark pine (Pinus albicaulis

Engelm.) in the Inland West. In The future of high-elevation, five-needle white pines in western North 

America: Proceedings of the High Five Symposium, 28–30 June 2010, Missoula, MT, ed. R.E. Keane, 

D.F. Tomback, M.P. Murray, and C.M. Smith, 124–39. USDA Forest Service, Rocky Mountain Research 

Station Proceedings RMRS-P-63, Fort Collins, CO. 

Mahalovich, M.F., M.J. Kimsey, J.K. Fortin-Noreus, and C.T. Robbins. 2016. Isotopic heterogeneity in whitebark 

pine (Pinus albicaulis Engelm.) nuts across geographic, edaphic and climatic gradients in the Northern 

Rockies (USA). Forest Ecology and Management 359: 174–89, doi:10.1016/j.foreco.2015.09.047. 

Maher, E.L., M.J. Germino, and N.J. Hasselquist. 2005. Interactive effects of tree and herb cover on 

survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone. Canadian 

Journal of Forest Research 35:567–74.

Maloney P.E. 2014. The multivariate underpinnings of recruitment for three Pinus species in montane forests of 

the Sierra Nevada, USA. Plant Ecology 215 (2): 261–74.

Maloney, P.E., D.R. Vogler, C.E. Jensen, and A.D. Mix. 2012. Ecology of whitebark pine populations in relation 

to white pine blister rust infection in subalpine forests of the Lake Tahoe Basin, USA: Implications for 

restoration. Forest Ecology and Management 280:166–75.

Maloy, O.C. 1997. White pine blister rust control in North America: A case history. Annual Review of 

Phytopathology 35:87–109.

Mancuso, M. 2013. Post-fire monitoring of whitebark pine communities on the Sawtooth National Recreation 

Area, Idaho. U.S. Fish and Wildlife Service, Idaho Fish and Wildlife Office, Boise, ID. 

Marlon, J.R., P.J. Bartlein, M.K. Walsh, S.P. Harrison, K.J. Brown, M.E. Edwards, P.E. Higuera, M.J. Power, 

R.S. Anderson, C. Briles, A. Brunelle, C. Carcaillet, M. Daniels, F.S. Hu, M. Lavoie, C. Long, T. Minckley, 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 85

P.J.H. Richard, A.C. Scott, D.S. Shafer, W. Tinner, C.E. Umbanhowar, Jr., and C. Whitlock. 2009. Wildfire 

responses to abrupt climate change in North America. Proceedings of the National Academy of Sciences 

of the USA 106 (8): 2519–24.

Mattson, D.J., K.C. Kendall, and D.P. Reinhart. 2001. Whitebark pine, grizzly bears, and red squirrels. 

In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 

121–37. Washington, DC: Island Press.

McCaughey, W.W. 1993. Delayed germination and seedling emergence of Pinus albicaulis in a high elevation 

clearcut in Montana, USA. In Proceedings – Symposium: Seed dormancy and barriers to germination, 

comp. D.G.W. Edwards, 67–72. Forestry Canada, Pacific Forestry Centre, International Union of Forestry 

Research Organizations (IUFRO) Project Group P2.04-00, Victoria, British Columbia, Canada. 

McCaughey, W.W., and W.C. Schmidt. 2001. Taxonomy, distribution, and history of whitebark pine. 

In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 

29–41. Washington, DC: Island Press.

McCaughey, W.W., G.L. Scott, and K.L. Izlar. 2009. Whitebark pine planting guidelines. Western Journal of 

Applied Forestry 24:163–66.

McCaughey, W.W., and T. Weaver. 1990. Biotic and microsite factors affecting whitebark pine establishment. 

In Proceedings—Symposium on whitebark pine ecosystems: Ecology and management of a highmountain resource, comp. W.C. Schmidt and K.J. McDonald, 140–50. USDA Forest Service, 

Intermountain Research Station, Gen. Tech. Rep. INT 270, Ogden, UT. 

McCool, S.F., and W.A. Freimund. 2001. Threatened landscapes and fragile experiences: Conflict in whitebark 

pine restoration. In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, 

and R.E. Keane, 263–88. Washington, DC: Island Press.

McDonald, G.I., and R.J. Hoff. 2001. Blister rust: An introduced plague. In Whitebark pine communities: 

Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 193–220. Washington, DC: Island 

Press.

McDonald, G.I., B.A. Richardson, P.J. Zambino, N.B. Klopfenstein, and M.S. Kim. 2006. Pedicularis and 

Castilleja are natural hosts of Cronartium ribicola in North America: A first report. Forest Pathology 

36:73–82.

McKenney, D.W., J.H. Pedlar, K. Lawrence, K. Campbell, and M.F. Hutchinson. 2007. Potential impacts of 

climate change on the distribution of North American trees. BioScience 57 (11): 939–48. 

McKinney, S.T., C.E. Fiedler, and D.F. Tomback. 2009. Invasive pathogen threatens bird-pine mutualism: 

Implications for sustaining a high-elevation ecosystem. Ecological Applications 19:597–607.

McKinney, S.T., and D.F. Tomback. 2007. The influence of white pine blister rust on seed dispersal in whitebark 

pine. Canadian Journal of Forest Research 37:1044–57.

Means, R.E., and J.S. Littell. 2014. Wildland Fire Change Agent. In Wyoming Basin ecoregional assessment: 

Final report, scientific investigative report. U.S. Geological Society, Fort Collins, CO.
86 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Meddens, A.J.H., J.A. Hicke, and C.A. Ferguson. 2012. Spatiotemporal patterns of observed bark beetlecaused tree mortality in British Columbia and the western United States. Ecological Applications 22 (7): 

1876–91.

Melillo, J.M., T.C. Richmond, and G.W. Yohe, eds. 2014. Climate change impacts in the United States: The 

third national climate assessment. U.S. Global Change Research Program.

Mielke, J.L. 1943. White pine blister rust in western North America. Yale University, School Forestry Bulletin 52, 

New Haven, CT.

Millar, C.I., N.L. Stephenson, and S.L. Stephens. 2007. Climate change and forests of the future: Managing in 

the face of uncertainty. Ecological Applications 17: 2145–51.

Minore, D. 1979. Comparative autecological characteristics of northwestern tree species: A literature review. 

USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Gen. Tech. Rep. PNW-87, 

Portland, OR. 

Mohatt, K.R., C.L. Cripps, and M. Lavin. 2008. Ectomycorrhizal fungi of whitebark pine (a tree in peril) 

revealed by sporocarps and molecular analysis of mycorrhizae from treeline forests in the Greater 

Yellowstone ecosystem. Botany 86:14–25.

Morgan, P., S.C. Bunting, R.E. Keane, and S.F. Arno. 1994. Fire ecology of whitebark pine (Pinus albicaulis) 

forests in the Rocky Mountains, USA. Proceedings of the international symposium: Subalpine stone pines 

and their environment: The status of our knowledge, comp. W. Schmidt and F. Holtzmeier, 136–42. 

St. Moritz, Switzerland.

National Climate Assessment. 2014. U.S. Global Change Research Program. 

http://nca2014.globalchange.gov/report

Norment, C.J. 1991. Bird use of forest patches in the subalpine forest-alpine tundra ecotone of the Beartooth 

Mountains, Wyoming. Northwest Science 65:1–10.

Ogilvie, R.T. 1990. Distribution and ecology of whitebark pine in western Canada. In Proceedings—Symposium 

on whitebark pine ecosystems: Ecology and management of a high-mountain resource, comp. W.C. 

Schmidt and K.J. McDonald, 54–60. USDA Forest Service, Intermountain Research Station, Gen. Tech. 

Rep. INT-270, Ogden, UT. 

Ojima, D., M. Shafer, J.M. Antle, D. Kluck, R.A. McPherson, S. Petersen, B. Scanlon, K. Sherman. 2014. Great 

Plains. Chap. 19. In Climate change impacts in the United States: The third national climate assessment, 

ed. J.M. Melillo, T.C. Richmond, and G.W. Yohe, 441–61. U.S. Global Change Research Program, 

doi: 10.7930/J0Z31WJ2. http://ncadac.globalchange.gov/

Ovaskainen, O., S. Skorokhodova, M. Yakovleva, A. Sukhov, A. Kutenkov, N. Kutenkova, A. Shcherbakov, 

E. Meyke, and M. del Mar Delgado. 2013. Community-level phenological response to climate change. 

Proceedings of the National Academy of Sciences 110 (33): 134–39. 

Owens, J.N., T. Kittirat, and M.F. Mahalovich. 2008. Whitebark pine (Pinus albicaulis Engelm.) seed production 

in natural stands. Forest Ecology and Management 255:803–9.
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 87

Perera, A.H., L.J. Buse, and M.G. Weber, eds. 2004. Emulating natural forest landscape disturbances: Concepts 

and applications. New York: Columbia University Press.

Perkins, D.L., and D.M. DeArmond. 2009. Limber pine and whitebark pine on BLM lands – A need for action. 

White paper, Bureau of Land Management, Boise, ID.

Perkins, D.L., C.L. Jorgensen, and M.J. Rinella. 2015. Verbenone decreases whitebark pine mortality 

throughout a mountain pine beetle outbreak. Forest Science 61 (4): 747–52. 

Perkins, D.L., and D.W. Roberts. 2003. Predictive models of whitebark pine mortality from mountain pine 

beetle. Forest Ecology and Management 174 (1-3): 495–510.

Perkins, D.L., and T.W. Swetnam. 1996. A dendroecological assessment of whitebark pine in the SawtoothSalmon River region, Idaho. Canadian Journal of Forest Research-Revue Canadienne De Recherche 

Forestiere 26 (12): 2123–33.

Pfister, R.D., B.L. Kovalchik, S.F. Arno, and R.C. Presby. 1977. Forest habitat types of Montana. USDA Forest 

Service, Intermountain Forest and Range Experiment Station, Gen. Tech. Rep. INT-34, Ogden, UT. 

Potter, K.M., V.D. Hipkins, M.F. Mahalovich, and R.E. Means. 2015. Nuclear genetic variation across the range 

of ponderosa pine (Pinus ponderosa): Phylogeographic, taxonomic, and conservation implications. Tree 

Genetics and Genomes 11 (3): 38. 

Powell, J.A., J.A. Logan, and B.J. Bentz. 1996. Local projections for a global model of mountain pine beetle 

attacks. Journal of Theoretical Biology 179:243–60.

Price, R.A., A. Liston, and S.H. Strauss. 1998. Phylogeny and systematics of Pinus. In Ecology and biogeography 

of Pinus, ed. D.M. Richardson, 49–68. Cambridge: Cambridge University Press.

Progar, R.A., N. Gillette, C.J. Fettig, and K. Hrinkevich. 2014. Applied chemical ecology of the mountain pine 

beetle. Forest Science 60 (3): 414–33.

Raffa, K.F., B.H. Aukema, N. Erbilgin, K.D. Klepzig, and K.F. Wallin. 2005. Interactions among conifer 

terpenoids and bark beetles across multiple levels of scale: An attempt to understand links between 

population patterns and physiologcal processes. In Recent advances in phytochemistry: Chemical 

ecology and phytochemistry of forest ecosystems, ed. J.T. Romeo, 79–118. Elsevier, Toronto, Canada. 

Ray, A.J., B. Liebmann, and D.A. Allured. 2015. Climate analysis. Chapter 7. In Wyoming Basin rapid 

ecoregional assessment: U.S. Geological Survey Open-File Report 2015-1155, ed. N.B. Carr, and C.P. 

Melcher, 165-203. U.S. Geological Survey in cooperation with the Bureau of Land Management. http://

dx.doi.org/10.3133/ ofr20151155.

Read, D.J. 1998. The mycorrhizal status of Pinus. In Ecology and biogeography of Pinus, ed. D.M. Richardson, 

324–40. Cambridge: Cambridge University Press.

Robbins, C.T., C.C. Schwartz, K.A. Gunther, and C. Servheen. 2006. Grizzly bear nutrition and ecology studies 

in Yellowstone National Park. Yellowstone Science 14 (3): 19–26. 
88 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Roe, A.L., and G.D. Amman. 1970. Mountain pine beetle in lodgepole pine forests. USDA Forest Service, 

Intermountain Forest and Range Experiment Station, Research Paper INT-71, Ogden, UT. 

Romme, W.H., and M.G. Turner. 1991. Implications of global climate change for biogeographic patterns in the 

greater Yellowstone ecosystem. Conservation Biology 5 (3): 373–86.

Safranyik, L., and A. Carroll. 2006. The biology and epidemiology of the mountain pine beetle in lodgepole 

pine forests. In The mountain pine beetle: A synthesis of biology, management, and impacts on 

lodgepole pine, ed. L. Safranyik and W. Wilson, 3–66. Canadian Forest Service, Pacific Forestry Centre, 

Victoria, British Columbia, Canada.

Schoettle, A.W., and R.A. Sniezko. 2007. Proactive intervention to sustain high-elevation pine ecosystems 

threatened by white pine blister rust. Journal of Forest Research 12 (5): 327–36.

Schoettle, A.W., R.A. Sniezko, A. Kegley, and K.S. Burns. 2014. White pine blister rust resistance in limber 

pine: Evidence for a major gene. Phytopathology 104 (2): 163–73.

Schrag, A.M., A.G. Bunn, and L.J. Graumlich. 2007. Influence of bioclimatic variables on tree-line conifer 

distribution in the Greater Yellowstone ecosystem: Implications for species of conservation concern. 

Journal of Biogeography 35: 698–710.

Schwandt, J.W. 2006. Whitebark pine in peril: A case for restoration. USDA Forest Service, Northern Region 

Forest Health Protection Report RI-06-28, Missoula, MT. 

Schwandt, J.W., and C. DeMastus. 2011. Whitebark Direct Seeding Trials. Nutcracker Notes 21:17–18.

Schwandt, J.W., H.S.J. Kearns, D.L. Miller, and B.A. Ferguson. 2013. Impacts of white pine blister rust in 22 

plantations of western white pine in northern Idaho: 1995–2011. USDA Forest Service, Northern Region, 

Forest Health Protection Report No. 13-08. 

Scott, G.L., and W.W. McCaughey. 2006. Whitebark pine guidelines for planting prescriptions. In National 

proceedings: Forest and conservation nursery associations, tech. coord. L.E. Riley, R.K. Dumroese, and 

T.D. Landis, 84–90. USDA Forest Service, Rocky Mountain Research Station Proceedings RMRS-P-43, Fort 

Collins, CO. 

Shanahan, E., K.M. Irvine, D. Roberts, A. Litt, K. Legg, and R. Daley. 2014. Status of whitebark pine in the 

Greater Yellowstone ecosystem: A step-trend analysis comparing 2004-2007 to 2008-2011. National 

Park Service, Natural Resource Technical Report NPS/GRYN/NRTR—2014/917, Fort Collins, CO.

Shoal, R., T. Ohlson, and C. Aubry. 2008. Land managers guide to whitebark pine restoration in the Pacific 

Northwest Region 2009–2013. USDA Forest Service, Pacific Northwest Region, Region 6 Report, 

Portland, OR.

Six, D.L. 2003. A comparison of mycangial and phoretic fungi of individual mountain pine beetles. Canadian 

Journal of Forest Research 33 (7): 1331–34. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 89

Six, D.L., and J. Adams. 2007. White pine blister rust severity and selection of individual whitebark pine by 

the mountain pine beetle (Coleoptera: Curculionidae, Scolytinae). Journal of Entomological Science 

42:345–53.

Six, D.L., and T.D. Paine. 1998. Effects of mycangial fungi and host tree species on progeny survival and 

emergence of Dendroctonus ponderosae (Coleoptera: Scolytidae). Environmental Entomology 

27:1393–1401.

Sniezko, R.A. 2006. Resistance breeding against nonnative pathogens in forest trees – current successes in 

North America. Canadian Journal of Plant Pathology 28:S270–79.

Sniezko, R.A., A.J. Kegley, R.S. Danchok, and S. Long. 2007. Variation in resistance to white pine blister 

rust among 43 whitebark pine families from Oregon and Washington – early results and implications 

for conservation. In Proceedings of the conference whitebark pine: Whitebark pine: A Pacific Coast 

perspective, tech. coord. E.M. Goheen and R.A. Sniezko, 82–97. USDA Forest Service, Pacific Northwest 

Region Proceedings R6-NR-FHP-2007-01, Portland, OR. 

Sniezko, R.A., M.F. Mahalovich, A.W. Schoettle, and D.R. Vogler. 2011. Past and current investigations of 

the genetic resistance to Cronartium ribicola in high-elevation five-needle pines. In The future of highelevation, five-needle white pines in western North America: Proceedings of the High Five Symposium, 

28–30 June 2010, Missoula, MT, ed. R.E. Keane, D.F. Tomback, M.P. Murray, and C.M. Smith, 246–64. 

USDA Forest Service, Rocky Mountain Research Station Proceedings RMRS-P-63, Fort Collins, CO. 

Society of American Foresters. 1998. The dictionary of forestry. Bethesda, MD.

Solheim, H., and P. Krokene. 1998. Growth and virulence of mountain pine beetle associated blue-stain fungi, 

Ophiostoma clavigerum and Ophiostoma montium. Canadian Journal of Botany 76 (4): 561–66.

Solomon, S., G.K. Plattner, R. Knutti, and P. Friedlingstein. 2009. Irreversible climate change due to carbon 

dioxide emissions. Proceedings of the National Academy of Sciences of the United States of America 

106 (6): 1704–9. 

Tausch, R.J., J.W. Burkhardt, C.L. Nowak, and P.E. Wigand. 1993. Viewpoint: Lessons from the past for 

managing tomorrows’ range ecosystems. Rangelands 15 (5): 196–99. 

Toevs, G.R., J.J. Taylor, C.S. Spurrier, W.C. MacKinnon, and M.R. Bobo. 2011. Assessment, inventory, and 

monitoring strategy: For integrated renewable resources management. Bureau of Land Management, 

National Operations Center, Denver, CO.

Tomback, D.F. 1978. Pre-roosting flight behavior of the Clark’s nutcracker. The Auk 95:554–62.

———. 1982. Dispersal of whitebark pine seeds by Clark’s nutcracker: A mutualism hypothesis. Journal of 

Animal Ecology 51 (2): 451–67.

———. 1986. Post-fire regeneration of krummholz whitebark pine: A consequence of nutcracker seed 

caching. Madroño 33:100–110. 

———. 2001. Clark’s nutcracker: Agent of regeneration. In Whitebark pine communities: Ecology and 

restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 89–104. Washington, DC: Island Press.
90 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States

Tomback, D.F., and P. Achuff. 2010. Blister rust and western forest biodiversity: Ecology, values and outlook for 

white pines. Forest Pathology 40 (3-4): 186–225.

Tomback, D.F., P. Achuff, A.W. Schoettle, J.W. Schwandt, and R.J. Mastrogiuseppe. 2011. The magnificent highelevation five-needle white pines: Ecological roles and future outlook. In The future of high-elevation, 

five-needle white pines in western North America: Proceedings of the High Five Symposium, 28–30 June 

2010, Missoula, MT, ed. R.E. Keane, D.F. Tomback, M.P. Murray, and C.M. Smith, 2–28. USDA Forest 

Service, Rocky Mountain Research Station Proceedings RMRS-P-63, Fort Collins, CO.

Tomback, D.F., A.J. Anderies, K.S. Carsey, M.L. Powell, and S. Mellman-Brown. 2001. Delayed seed germination 

in whitebark pine and regeneration patterns following the Yellowstone fires. Ecology 82:2587–2600.

Tomback, D.F., S.F. Arno, and R.E. Keane. 2001a. The compelling case for management intervention. 

In Whitebark pine communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 

3–25. Washington, DC: Island Press.

———, eds. 2001b. Whitebark pine communities: Ecology and restoration. Washington, DC: Island Press.

Tomback, D.F., K.G. Chipman, L.M. Resler, E.K. Smith-McKenna, and C.P. Smith. 2014. Relative abundance 

and functional role of whitebark pine at treeline in the northern Rocky Mountains. Arctic, Antarctic, and 

Alpine Research 46 (2): 407–18.

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

for forest regeneration. In Proceedings—Symposium on whitebark pine ecosystems: Ecology and 

management of a high-mountain resource, comp. W.C. Schmidt and K.J. McDonald, 118–29. USDA 

Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-270, Ogden, UT. 

Tomback, D.F., and K.C. Kendall. 2001. Biodiversity losses: The downward spiral. In Whitebark pine 

communities: Ecology and restoration, ed. D.F. Tomback, S.F. Arno, and R.E. Keane, 243–62. Washington, 

DC: Island Press.

Tomback, D.F., and Y.B. Linhart. 1990. The evolution of bird-dispersed pines. Evolutionary Ecology 4:185–219.

Tomback, D.F., S.K. Sund, and L.A. Hoffman. 1993. Post-fire regeneration of Pinus albicaulis: Height-age 

relationships, age structure, and microsite characteristics. Canadian Journal of Forest Research 23:113–19.

U.S. Department of Agriculture, Natural Resources Conservation Service. PLANTS Database (accessed October 2, 

2015). National Plant Data Team, Greensboro, NC. http://plants.usda.gov

van Mantgem, P.J., N.L. Stephenson, J.C. Byrne, L.D. Daniels, J.F. Franklin, P.Z. Fule, M.E. Harmon, A.J. Larson, 

J.M. Smith, A.H. Taylor, and T.T. Veblen. 2009. Widespread increase of tree mortality rates in the western 

United States. Science 323 (5913): 521–24. 

Vergeer, P., and W.E. Kunin. 2012. Adaptation at range margins: Common garden trials and the performance of 

Arabidopsis lyrata across its northwestern European range. New Phytologist 197 (3): 989–1001. 
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 91

Vogler, D.R., A. Delfino-Mix, and A.W. Schoettle. 2006. White pine blister rust in high-elevation white pines: 

Screening for simply-inherited, hypersensitive resistance. In Proceedings of the 53rd Western International 

Forest Disease Work Conference, September 26–30, 2005, comp. J.C. Guyon. USDA Forest Service, 

Intermountain Region, Ogden, UT. 

Ward, K., R. Shoal, and C. Aubry. 2006a. Whitebark pine cone collection manual. USDA Forest Service, Pacific 

Northwest Region, Albicaulis Project, OR and WA.

———. 2006b. Whitebark pine in Washington and Oregon: A synthesis of current studies and historical data. 

USDA Forest Service, Pacific Northwest Region, Portland, OR.

Waring, K.M., and D.L. Six. 2005. Distribution of bark beetle attacks after whitebark pine restoration treatments: 

A case study. Western Journal of Applied Forestry 20:110–16.

Warwell, M.V., G.E. Rehfeldt, and N.L. Crookston. 2007. Modeling contemporary climate profiles of whitebark 

pine (Pinus albicaulis) and predicting responses to global warming. In Proceedings of the conference 

whitebark pine: A Pacific Coast perspective, 139–42. USDA Forest Service, Pacific Northwest Region, 

Portland, OR.

Weaver, T., and F. Forcella. 1986. Cone production in Pinus albicaulis forests. USDA Forest Service, Gen. Tech. 

Rep. INT-203, Ogden, UT. 

Westerling, A.L., H.G. Hidalgo, D.R. Cayan, and T.W. Swetnam. 2006. Warming and earlier spring increase 

western U.S. forest wildfire activity. Science 313:940–43.

Whitlock, C., and P.J. Bartlein. 1993. Spatial variations of Holocene climatic change in the Yellowstone region. 

Quaternary Research 39:231–38.

Wikelski, M., and S.J. Cooke. 2006. Conservation physiology. Trends in Ecology and Evolution 21:38–46.

Willard, E.E. 1990. Use and impact of domestic livestock in whitebark pine forests. In Proceedings— Symposium 

on whitebark pine ecosystems: Ecology and management of a high-mountain resource, comp. 

W.C. Schmidt and K.J. McDonald, 201–7. USDA Forest Service, Intermountain Research Station, Gen. 

Tech. Rep. INT-270, Ogden, UT. 

Williams, B.K., R.C. Szaro, and C.D. Shapiro. 2009. Adaptive management: The Department of the Interior 

technical guide. Adaptive Management Working Group, U.S. Department of the Interior, Washington, DC.

Wilson, B.C., and G.J. Stuart-Smith. 2002. Whitebark pine conservation for the Canadian Rocky Mountain 

national parks. KNP01-01, Parks Canada, Radium Hot Springs, British Columbia, Canada.
92 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States
 Conservation and Management of Whitebark Pine Ecosystems on Bureau of Land Management Lands in the Western United States 93

Notes
Photo by Famartin (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of 

the Interior of any product or service.