Climate Change Vulnerability and Adaptation 

in the Northern Rocky Mountains

Part 2

Jessica E. Halofsky, David L. Peterson, S. Karen Dante-Wood, Linh Hoang, Joanne J. Ho, 

Linda A. Joyce, Editors

Forest Rocky Mountain General Technical Report

Service Research Station RMRS-GTR-374 March 2018

United States Department of Agriculture
Halofsky, Jessica E.; Peterson, David L.; Dante-Wood, S. Karen; Hoang, Linh; Ho, Joanne J.; Joyce, Linda A., eds. 

2018. Climate change vulnerability and adaptation in the Northern Rocky Mountains. Gen. Tech. Rep. RMRSGTR-374. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

Part 2. pp. 275–475.

Abstract

The Northern Rockies Adaptation Partnership (NRAP) identified climate change issues relevant to resource 

management in the Northern Rockies (USA) region, and developed solutions intended to minimize negative effects 

of climate change and facilitate transition of diverse ecosystems to a warmer climate. The NRAP region covers 183 

million acres, spanning northern Idaho, Montana, northwestern Wyoming, North Dakota, and northern South Dakota, 

and includes 15 national forests and 3 national parks across the U.S. Forest Service Northern Region and adjacent 

Greater Yellowstone Area. U.S. Forest Service scientists, resource managers, and stakeholders worked together 

over 2 years to conduct a state-of-science climate change vulnerability assessment and develop adaptation options 

for national forests and national parks in the Northern Rockies region. The vulnerability assessment emphasized 

key resource areas—water, fisheries, wildlife, forest and rangeland vegetation and disturbance, recreation, cultural 

heritage, and ecosystem services—regarded as the most important for local ecosystems and communities. Resource 

managers used the assessment to develop a detailed list of ways to address climate change vulnerabilities through 

management actions. The large number of adaptation strategies and tactics, many of which are a component of 

current management practice, provide a pathway for slowing the rate of deleterious change in resource conditions.

Keywords: adaptation, climate change, ecological disturbance, climate-smart resource management, Northern 

Rocky Mountains, vulnerability assessment

Front cover: Top left, Twin Lakes Campground, Beaverhead-Deerlodge National Forest; top right, Holland Lake, Flathead National 

Forest; bottom left, Horse Prairie Guard Station, Beaverhead-Deerlodge National Forest; bottom right, Rock Creek, Lolo National 

Forest (photos, Eric Henderson, used with permission).

All Rocky Mountain Research Station publications are published by U.S. Forest Service employees and are in the 

public domain and available at no cost. Even though U.S. Forest Service publications are not copyrighted, they 

are formatted according to U.S. Department of Agriculture standards and research findings and formatting cannot 

be altered in reprints. Altering content or formatting, including the cover and title page, is strictly prohibited.
Editors

Jessica E. Halofsky is a Research Ecologist with the University of Washington, College of the Environment, School 

of Environmental and Forest Sciences in Seattle, Washington.

David L. Peterson was a Senior Research Biological Scientist with the U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station in Seattle, Washington. He is currently a professor with the University of 

Washington, School of Environmental and Forest Sciences, Seattle, Washington.

S. Karen Dante-Wood is a Natural Resource Specialist, U.S. Department of Agriculture, Forest Service, Office of 

Sustainability and Climate in Washington, DC.

Linh Hoang is the Regional Inventory, Monitoring, Assessment and Climate Change Coordinator, U.S. Department of 

Agriculture, Forest Service, Northern Region in Missoula, Montana.

Joanne J. Ho is a Research Environmental Economist with the University of Washington, School of Environmental 

and Forest Sciences in Seattle, Washington.

Linda A. Joyce is a Research Ecologist with the U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station, Human Dimensions Research Program in Fort Collins, Colorado.

Summary

The Northern Rockies Adaptation Partnership (NRAP) is a science-management partnership consisting of 15 national 

forests in the Northern Region of the Forest Service, U.S. Department of Agriculture (USFS); 3 national parks; the 

USFS Pacific Northwest and Rocky Mountain Research Stations; the University of Washington; and numerous other 

organizations and stakeholders. These organizations worked together over a period of 2 years to identify climate 

change issues relevant to resource management in the Northern Rocky Mountains (USA) and to find solutions that 

can minimize negative effects of climate change and facilitate transition of diverse ecosystems to a warmer climate. 

The NRAP provided education, conducted a climate change vulnerability assessment, and developed adaptation 

options for national forests and national parks that manage more than 28 million acres in northern Idaho, Montana, 

northwestern Wyoming, North Dakota, and northern South Dakota.

Global climate models project that the Earth’s current warming trend will continue throughout the 21st century in the 

Northern Rockies. Compared to observed historical temperature, average warming across the five NRAP subregions 

is projected to be about 4 to 5 °F by 2050, depending on greenhouse gas emissions. Precipitation may increase 

slightly in the winter, although the magnitude is uncertain.

Climatic extremes are difficult to project, but they will probably be more common, driving biophysical changes in 

terrestrial and aquatic ecosystems. Droughts of increasing frequency and magnitude are expected in the future, 

promoting an increase in wildfires, insect outbreaks, and nonnative species. These periodic disturbances, will rapidly 

alter productivity and structure of vegetation, potentially altering the distribution and abundance of dominant plant 

species and animal habitat.

Highlights of the vulnerability assessment and adaptation options for the Northern Rockies include the following:

Water resources and infrastructure

• Effects: Decreasing snowpack and declining summer flows will alter timing and availability of water supply, 

affecting agricultural, municipal, and public uses in and downstream from national forests, and affecting other 

forest uses such as livestock, wildlife, recreation, firefighting, road maintenance, and instream fishery flows. 

Declining summer low flows will affect water availability during late summer, the period of peak demand (e.g., 

for irrigation and power supply). Increased magnitude of peak streamflows will damage roads near perennial 

streams, ranging from minor erosion to extensive damage, thus affecting public safety, access for resource 

management, water quality, and aquatic habitat. Bridges, campgrounds, and national forest facilities near 

streams and floodplains will be especially vulnerable, reducing access by the public.

• Adaptation options: Primary adaptation strategies to address changing hydrology in the Northern Rockies include 

restoring the function of watersheds, connecting floodplains, reducing drainage efficiency, maximizing valley 

storage, and reducing hazardous fuels. Tactics include adding wood to streams, restoring beaver populations, 

modifying livestock management, and reducing surface fuels and forest stand densities. Primary strategies for 
infrastructure include increasing the resilience of stream crossings, culverts, and bridges to higher peakflows and 

facilitating response to higher peakflows by reducing the road system and disconnecting roads from streams. 

Tactics include completing geospatial databases of infrastructure (and drainage) components, installing higher 

capacity culverts, and decommissioning roads or converting them to alternative uses. It will be important to 

map aquifers and alluvial deposits, improve monitoring to provide feedback on water dynamics, and understand 

the physical and legal availability of water for aquifer recharge. Erosion potential to protect water quality can 

be addressed by reducing hazardous fuels in dry forests, reducing nonfire disturbances, and using road 

management practices that prevent erosion.

Fisheries

• Effects: Decreased snowpack will shift the timing of peakflows, decrease summer low flows, and in combination 

with higher air temperature, increase stream temperatures, all of which will reduce the vigor of cold-water fish 

species. Abundance and distribution of cutthroat trout and especially bull trout will be greatly reduced, although 

effects will differ by location as a function of both stream temperature and competition from nonnative fish 

species. Increased wildfire will add sediment to streams, increase peakflows and channel scouring, and raise 

stream temperature by removing vegetation.

• Adaptation options: Primary strategies to address climate change threats to coldwater fish species include 

maintaining or restoring functionality of channels and floodplains to retain (hence, to cool) water and buffer 

against future changes, decreasing fragmentation of stream networks so aquatic organisms can reach similar 

habitats, and developing wildfire use plans that address sediment inputs and road failures. Adaptation tactics 

include using watershed analysis to develop integrated actions for vegetation and hydrology, protecting 

groundwater and springs, restoring riparian areas and beaver populations to maintain summer baseflows, 

reconnecting and increasing off-channel habitat and refugia, identifying and improving stream crossings that 

impede fish movement, decreasing road connectivity, and revegetating burned areas to store sediment and 

maintain channel geomorphology. Removing nonnative fish species and reducing their access to cold water 

habitat reduces competition with native fish species.

Forest vegetation

• Effects: Increasing air temperature, through its influence on soil moisture, is expected to cause gradual changes 

in the abundance and distribution of tree, shrub, and grass species throughout the Northern Rockies, with 

more drought-tolerant species becoming more competitive. The earliest changes will be at ecotones between 

lifeforms (e.g., upper and lower treelines). Ecological disturbance, including wildfire and insect outbreaks, will 

be the primary facilitator of vegetation change, and future forest landscapes may be dominated by younger age 

classes and smaller trees. High elevation forests will be especially vulnerable if disturbance frequency increases 

significantly. Increased abundance and distribution of nonnative plant species, as well as the legacy of past land 

uses, create additional stress for regeneration of native forest species.

• Adaptation options: Most strategies for conserving native tree, shrub, and grassland systems focus on increasing 

resilience to chronic low soil moisture (especially extreme drought and low snowpack), and to more frequent 

and extensive ecological disturbance (wildfire, insects, nonnative species). These strategies generally include 

managing landscapes to reduce the severity and patch size of disturbances, encouraging fire to play a more 

natural role, and protecting refugia where fire-sensitive species can persist. Increasing species, genetic, and 

landscape diversity (spatial pattern, structure) is an important “hedge your bets” strategy that will reduce the 

risk of major forest loss. Adaptation tactics include using silvicultural prescriptions (especially stand density 

management) and fuels treatments to reduce fuel continuity, reducing populations of nonnative species, 

potentially using multiple genotypes in reforestation, and revising grazing policies and practices. Rare and 

disjunct species and communities (e.g., whitebark pine, quaking aspen) require adaptation strategies and tactics 

focused on encouraging regeneration, preventing damage from disturbance, and establishing refugia.

Rangeland vegetation

• Effects: A longer growing season is expected to increase net primary productivity of many rangeland types, 

especially those dominated by grasses, although responses will depend on local climate and soil conditions. 

Elevated atmospheric carbon dioxide may increase water use efficiency and productivity of some species. In 

many cases, increasing wildfire frequency and extent will be particularly damaging for big sagebrush and other 

shrub species that are readily killed by fire. The widespread occurrence of cheatgrass and other nonnative 

species facilitates frequent fire through annual fuel accumulation. In montane grasslands, wildfire may kill 

Douglas-fir and other species that have recently established in rangelands through fire exclusion. Shrub species 

that sprout following fire may be very resilient to increased disturbance, but may be outcompeted by more 

drought-tolerant species over time.

ii
• Adaptation options: Adaptation strategies for rangeland vegetation focus on increasing resilience of rangeland 

ecosystems, primarily through control and prevention of invasion by nonnative species. Ecologically based 

management of nonnative plants focuses on strategies to repair damaged ecological processes that facilitate 

invasion, and seeding of desired native species can be done where seed availability and dispersal of these 

species are low. Proactive management to prevent establishment of nonnative species is also critical (early 

detection-rapid response), including tactics such as weed-free policies, education of employees and the public, 

and collaboration among multiple agencies to control weeds. Livestock grazing can also be managed through 

the development of site-specific indicators that inform livestock movement guides and allow for maintenance and 

enhancement of plant health.

Wildlife

• Effects: Few data exist on the direct effects of climatic variability and change on most animal species. Therefore, 

projected climate change effects must be inferred from what is known about habitat characteristics and the 

autecology of each species. Habitat for mammals that depend on high-elevation, snowy environments, whether 

predators (Canada lynx, fisher, wolverine) or prey (snowshoe hare), is expected to deteriorate relatively soon if 

snowpack continues to decrease. Species that are highly dependent on a narrow range of habitat (pygmy rabbit, 

Brewer’s sparrow, greater sage-grouse) will be especially vulnerable if that habitat decreases from increased 

disturbance (e.g., sagebrush mortality from wildfire). Species that are mobile or respond well to increased 

disturbance and habitat patchiness (deer, elk) will probably be resilient to a warmer climate in most locations. 

Some amphibian species (Columbia spotted frog, western toad) may be affected by pathogens (e.g., amphibian 

chytrid fungus) that are favored by a warmer climate.

• Adaptation options: Adaptation strategies for wildlife are focused on maintaining adequate habitat and healthy 

wildlife populations, and increasing knowledge of the needs and climate sensitivities of species. Connectivity 

is an important conservation strategy for most species in the Northern Rockies. Maintaining healthy American 

beaver populations will provide riparian habitat structure and foraging opportunities for multiple species. Quaking 

aspen habitat, which is also important for several species, can be enhanced by allowing wildfire, protecting 

aspen from grazing, and reducing conifer encroachment. Restoration of more-open stands of ponderosa pine 

and mixed-conifer forest through reduction of stand densities will benefit species such as fisher and flammulated 

owl. Excluding fire and reducing nonnative species will maintain sagebrush habitats that are required by several 

bird and mammal species.

Recreation

• Effects: Recreation has a significant economic impact throughout the Northern Rockies. A warmer climate will 

generally improve opportunities for warm weather activities (hiking, camping, sightseeing) because it will create 

a longer time during which these activities are possible, especially in the spring and fall “shoulder seasons.” 

However, it will reduce opportunities for snow-based, winter activities (downhill skiing, cross-country skiing, 

snowmobiling) because snowpack is expected to decline significantly in the future. Recreationists will probably 

seek more water-based activities in lakes and rivers as refuge from hotter summer weather. Higher temperatures 

may have both positive and negative effects on wildlife-based activities (hunting, fishing, birding) and gathering of 

forest products (e.g., berries, mushrooms), depending on how target habitats and species are affected.

• Adaptation options: Recreationists are expected to be highly adaptable to a warmer climate by shifting to different 

activities and different locations, behavior that is already observed from year to year. For example, downhill 

skiers may switch to ski areas that have more reliable snow, cross-country skiers will travel to higher elevations, 

and larger ski areas on Federal lands may expand to multi-season operation. Water-based recreationists may 

adapt to climate change by choosing different sites that are less susceptible to changes in water levels. Hunters 

may need to adapt by altering the timing and location of hunts. Federal management of recreation is currently 

not very flexible with respect to altered temporal and spatial patterns of recreation. This can be at least partially 

resolved by assessing expected use patterns in a warmer climate, modifying opening times of facilities, and 

deploying seasonal employees responsible for recreational facilities earlier in the year.

Ecosystem services

Ecosystem services are increasingly valued on Federal lands, beyond just their economic value. Climate change 

effects will vary greatly within different subregions of the Northern Rockies, with some ecosystem services being 

affected in the short term and others in the long term. Of the many ecosystem services provided in the Northern 

Rockies, eight are considered here, most of which are relevant to other resource categories included in the 

assessment.

• Although annual water quantity (or water yield or water supply) is not expected to change significantly, timing 

of water availability is likely to shift, and summer flows may decline. These changes may result in some 

iii
communities experiencing summer water shortages, although reservoir storage can provide some capacity. Rural 

agricultural communities will be disproportionately affected by climate change if water does become limiting.

•	 Water quality will decrease in some locations if wildfires and floods increase, adding sediment to rivers and 

reservoirs. Agriculture is currently the major source of impairment, affecting riparian systems, aquatic habitat, 

water temperatures, and fecal coliform. Climate change is expected to amplify these effects. Hazardous fuels 

treatments, riparian restoration, and upgrading of hydrologic infrastructure can build resilience to disturbances 

that damage water quality.

•	 Wood products are a relatively small component of the Northern Rockies economy, and economic forces will 

probably have the biggest impacts in the future. As wildfires and insect outbreaks become more common, wood 

supply could become less reliable, but overall effects will generally be small except in small towns that depend 

on a steady timber supply.

•	 Minerals and mineral extraction are important economic drivers in eastern Montana and western North Dakota. 

The biggest effects on this industry will be economic factors and factors related to how it connects to other 

ecosystem services, particularly water quality. Wildfires and floods can put mineral extraction infrastructure at risk 

in some watersheds.

•	 Forage for livestock is expected to increase in productive grasslands as a result of a longer growing season 

and in some cases elevated carbon dioxide. Therefore, ranching and grazing may benefit from climate change. 

Primary effects on grazing include loss of rural population, spread of nonnative grasses, and fragmentation of 

rangelands.

•	 Viewsheds and air quality will be negatively affected by increasing wildfires and longer pollen seasons. A growing 

percentage of the Northern Rockies population will be in demographic groups at risk for respiratory and other 

medical problems on days with poor air quality. Treatments of hazardous fuels can help build resilience to 

disturbances that degrade air quality.

•	 Regulation of soil erosion will be decreased by agricultural expansion, spread of nonnative plants, and increased 

frequency of wildfire and floods. Increased capital investments may be needed for water treatment plants if water 

quality declines significantly. Climate-smart practices in agriculture and road construction can reduce some 

negative effects.

•	 Carbon sequestration will be increasingly difficult if wildfires, insect outbreaks, and perhaps plant disease 

increase as expected, especially in the western part of the Northern Rockies. At the same time, managing forests 

for carbon sequestration is likely to become more important in response to national policies on carbon emissions. 

Hazardous fuels treatments can help build resilience to disturbances that rapidly oxidize carbon and emit it to the 

atmosphere.

Cultural resources

• Disturbances such as wildfires, floods, and soil erosion place cultural and heritage values at risk. Damage to 

cultural and historic sites is irreversible, making protection a key management focus. Climate-induced changes in 

terrestrial and aquatic habitats affect abundance of culturally valued plants and animals (especially fish), affecting 

the ability of Native American tribes to exercise their treaty rights. Effects on cultural resources are amplified by 

external social forces that include a growing regional population, vandalism, and loss of traditional practices in a 

globalizing culture.

Conclusions

The NRAP facilitated the largest climate change adaptation effort on public lands to date. This collaboration included 

participants from Federal agencies and stakeholder organizations interested in a broad range of resource issues. It 

achieved specific goals of national climate change strategies for the USFS and National Park Service, providing a 

scientific foundation for resource management and planning in the Northern Rockies. The large number of adaptation 

strategies and tactics, many of which are a component of current management practice, provide a pathway 

for slowing the rate of deleterious change in resource conditions. Rapid implementation of adaptation—in land 

management plans, National Environmental Policy Act documents, project plans, and restoration—will help maintain 

functionality of terrestrial and aquatic ecosystems in the Northern Rockies, as well as build the organizational capacity 

of Federal agencies to incorporate climate change in their mission of sustainable resource management. Long-term 

monitoring will help detect potential climate change effects on natural resources, and evaluate the effectiveness of 

adaptation options that have been implemented.

iv
Contents—Part 2

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the 

Northern Rockies Region ...................................................................................... 275

Matt C. Reeves, Mary E. Manning, Jeff P. DiBenedetto, Kyle A. Palmquist, William K. Lauenroth, 

John B. Bradford, and Daniel R. Schlaepfer

Introduction.................................................................................................................................... 275

Vegetation Classes .......................................................................................................................... 276

Vegetation Productivity in Response to Climate Change.................................................................. 278

Management Concerns....................................................................................................................... 281

Broad-Scale Vulnerability of Rangelands to Climate Change ........................................................... 282

Northern Great Plains, Dominated by Mixtures of Cool-Season and Warm-Season Grasses ................ 282

Communities Dominated by Montane Shrubs..................................................................................... 283

Montane Grasslands ........................................................................................................................... 284

Sagebrush Systems.............................................................................................................................. 284

Adapting Rangeland Vegetation Management to Climate Change in the Northern Rockies Region .. 290

References...................................................................................................................................... 294

Appendix 7A—Adaptation Options for Nonforest Vegetation in the Northern Rockies .................... 299

Chapter 8: Effects of Climate Change on Ecological Disturbance in the 

Northern Rockies Region ...................................................................................... 317

Rachel A. Loehman, Barbara J. Bentz, Gregg A. DeNitto, Robert E. Keane, Mary E. Manning, 

Jacob P. Duncan, Joel M. Egan, Marcus B. Jackson, Sandra Kegley, I. Blakey Lockman, 

Dean E. Pearson, James A. Powell, Steve Shelly, Brytten E. Steed, and Paul J. Zambino

Introduction.................................................................................................................................... 317

Wildfire .......................................................................................................................................... 317

Overview............................................................................................................................................ 317

Potential Future Wildfire Regimes and Wildfire Occurrence................................................................ 322

Unknowns and Uncertainties.............................................................................................................. 324

Bark Beetles.................................................................................................................................... 325

Overview............................................................................................................................................ 325

Bark Beetles in the Northern Rockies .................................................................................................. 325

Drivers of Bark Beetle Outbreaks ........................................................................................................ 327

Bark Beetle Outbreaks Shape Landscape Patterns................................................................................ 327

Potential Future Bark Beetle Regimes and Occurrence........................................................................ 328

Expected Effects of Climate Change .................................................................................................... 329

Interactions with Other Disturbance Processes.................................................................................... 330

Unknowns and Uncertainties.............................................................................................................. 330

White Pine Blister Rust.................................................................................................................... 333

Overview............................................................................................................................................ 333

Effects of Climate Change on White Pine Blister Rust .......................................................................... 334

Interactions with Other Disturbance Processes.................................................................................... 334

Unknowns and Uncertainties.............................................................................................................. 335

Forest Diseases................................................................................................................................ 336

Overview............................................................................................................................................ 336

Broad-Scale Climate Drivers of Forest Diseases................................................................................... 339

Effects of Climate Change on Forest Diseases...................................................................................... 339

Forest Pathogen Interactions................................................................................................................ 341

Nonnative Plants............................................................................................................................. 342

Overview............................................................................................................................................ 342

Effects of Climate Change on Nonnative Species................................................................................. 342

References...................................................................................................................................... 344

v
Chapter 9: Climate Change and Wildlife in the Northern Rockies Region............ 353

Kevin S. McKelvey and Polly C. Buotte 

How Climate Affects Wildlife.......................................................................................................... 353

The Importance of Community in Defining Habitat......................................................................... 355

Evaluating Sensitivity of Species to Climate Change ........................................................................ 356

Mammals............................................................................................................................................ 356

Birds................................................................................................................................................... 364

Amphibians ........................................................................................................................................ 366

Assessing Subregional Differences in Vulnerability.......................................................................... 367

Adapting Wildlife Management to the Effects of Climate Change .................................................... 368

Acknowledgments........................................................................................................................... 370

References...................................................................................................................................... 370

Apendix 9A—Adaptation Options for Wildlife in the Northern Rockies .......................................... 381

Chapter 10: Effects of Climate Change on Recreation in the 

Northern Rockies Region ...................................................................................... 398

Michael S. Hand and Megan Lawson

Introduction.................................................................................................................................... 398

Relationships Between Climate Change and Recreation.................................................................. 398

Identifying Climate-Sensitive Outdoor Recreation Activities............................................................ 399

Climate Change Vulnerability Assessment ....................................................................................... 400

Current Conditions and Existing Stressors............................................................................................ 402

Current Management .......................................................................................................................... 402

Warm-Weather Activities.................................................................................................................... 405

Cold-Weather Activities ...................................................................................................................... 406

Wildlife Activities................................................................................................................................ 408

Gathering Forest Products................................................................................................................... 409

Water-Based Activities, not Including Fishing...................................................................................... 409

Summary ............................................................................................................................................ 410

Adapting Recreation to the Effects of Climate Change ..................................................................... 411

Adaptation by Recreation Participants................................................................................................. 411

Adaptation by Public Land Managers.................................................................................................. 411

References...................................................................................................................................... 413

Appendix 10A—Adaptation Options for Recreation in the Northern Rockies.................................. 415

Chapter 11: Effects of Climate Change on Ecosystem Services in the 

Northern Rockies Region ...................................................................................... 434

Travis Warziniack, Megan Lawson, and S. Karen Dante-Wood

Introduction.................................................................................................................................... 434

Ecosystem Services and Public Lands.............................................................................................. 435

Ecosystem Services in the Northern Rockies Region........................................................................ 435

Social Vulnerability and Adaptive Capacity ..................................................................................... 436

Ecosystem Service: Water Quantity ................................................................................................. 439

Effects of Climate Change ................................................................................................................... 440

Adaptive Capacity............................................................................................................................... 441

Risk Assessment .................................................................................................................................. 441

Ecosystem Service: Water Quality, Aquatic Habitats, and Fish for Food........................................... 441

Effects of Climate Change ................................................................................................................... 444

Adaptive Capacity............................................................................................................................... 445

Risk Assessment .................................................................................................................................. 445

Ecosystem Service: Building Materials and other Wood Products.................................................... 445

Effects of Climate Change ................................................................................................................... 449

Forest Products (Commercial Use)....................................................................................................... 449

vi
Adaptive Capacity............................................................................................................................... 450

Risk Assessment .................................................................................................................................. 450

Ecosystem Service: Mining Materials............................................................................................... 450

Effects of Climate Change ................................................................................................................... 451

Adaptive Capacity............................................................................................................................... 451

Risk Assessment .................................................................................................................................. 451

Ecosystem Service: Forage For Livestock.......................................................................................... 451

Effects of Climate Change ................................................................................................................... 452

Adaptive Capacity............................................................................................................................... 452

Risk Assessment .................................................................................................................................. 452

Ecosystem Service: Viewsheds And Clean Air.................................................................................. 453

Effects of Climate Change ................................................................................................................... 453

Adaptive Capacity............................................................................................................................... 453

Risk Assessment .................................................................................................................................. 453

Ecosystem Service: Regulation of Soil Erosion................................................................................. 453

Effects of Climate Change ................................................................................................................... 454

Adaptive Capacity............................................................................................................................... 454

Risk Assessment .................................................................................................................................. 454

Ecosystem Service: Carbon Sequestration........................................................................................ 454

Baseline Estimates............................................................................................................................... 455

Effects of Climate Change ................................................................................................................... 456

Adaptive Capacity............................................................................................................................... 456

Risk Assessment .................................................................................................................................. 456

Ecosystem Service: Cultural and Heritage Values............................................................................. 457

Effects of Climate Change ................................................................................................................... 457

Adaptive Capacity............................................................................................................................... 457

Risk Assessment .................................................................................................................................. 457

Summary ........................................................................................................................................ 457

References...................................................................................................................................... 458

Chapter 12: Effects of Climate Change on Cultural Resources in the 

Northern Rockies Region ...................................................................................... 462

Carl M. Davis

Background and Cultural Context in the Northern Rockies Region.................................................. 462

Broad-Scale Climate Change Effects on Cultural Resources............................................................. 462

Risk Assessment .................................................................................................................................. 466

Adapting to the Effects of Climate Change....................................................................................... 467

References...................................................................................................................................... 468

Chapter 13: Conclusions ........................................................................................... 469

S. Karen Dante-Wood and Linh Hoang

Relevance to Agency Climate Change Response Strategies.............................................................. 469

Organization Capacity, Education, and Communication ..................................................................... 469

Partnerships and Engagement.............................................................................................................. 469

Assessing Vulnerability and Adaptation ............................................................................................... 470

Science and Monitoring...................................................................................................................... 472

Next Steps....................................................................................................................................... 472

Implementing Adaptation Strategies and Tactics.................................................................................. 472

Applications........................................................................................................................................ 473

References...................................................................................................................................... 475

vii
USDA Forest Service RMRS-GTR-374. 2018 275

Introduction

Rangelands are dominated by grass, forb, or shrub 

species, but are usually not modified by using agronomic 

improvements such as fertilization or irrigation (Lund 2007; 

Reeves and Mitchell 2011) as these lands would normally 

be considered pastures. Rangeland includes grassland, 

shrubland, and desert ecosystems, alpine areas, and some 

woodlands (box 7.1). This chapter addresses the potential 

effects of climate change on rangeland vegetation in the 

Forest Service, U.S. Department of Agriculture (USFS) 

Northern Region and the Greater Yellowstone Area (GYA), 

hereafter called the Northern Rockies region. Within the 

Northern Rockies region, rangelands occupy more than 

65 million acres (Reeves and Mitchell 2011). Ecosystem 

services derived from these rangelands include forage for 

millions of domestic and wild ungulates, greater sagegrouse (Centrocercus urophasianus) habitat, and numerous 

recreational opportunities (see Chapter 10).

The sustainability of goods and services is threatened by 

land-use change, such as residential development, energy 

development, and invasion by nonnative plant species (see 

Chapter 11). These threats, expressed against the backdrop 

of climate change, pose unique challenges for managers in 

the Northern Rockies region. The effects of climate change 

on rangelands have received less attention than effects on 

forests, but similar to forests, past and future human landuse activities may exceed climate change effects, at least 

in the short term (Peilke et al. 2002). Interactions among 

land-use change, management, and climate change are not 

well understood and are difficult to forecast. Therefore, this 

analysis of potential climate change effects on rangelands 

does not explicitly include estimates of future land-use 

change or management, and instead focuses on estimated 

regeneration success, response to disturbance (especially 

fire), and life history traits.

Relative to forests, rangelands usually occur in more 

arid environments, either due to edaphic (e.g., some montane grasslands, subalpine shrublands, and fell-fields) or 

climatic factors. These arid conditions present challenges 

for studying the effects of climate change because some 

rangelands will be less resilient to changes in environmental 

Chapter 7: Effects of Climate Change on 

Rangeland Vegetation in the Northern 

Rockies Region

Matt C. Reeves, Mary E. Manning, Jeff P. DiBenedetto, Kyle A. Palmquist, 

William K. Lauenroth, John B. Bradford, and Daniel R. Schlaepfer

Box 7.1—Rangeland Definitions used by Different Federal Agencies

U.S. Forest Service

Land primarily composed of grasses, forbs, or shrubs. This includes lands vegetated naturally or artificially to provide 

a plant cover managed like native vegetation and does not meet the definition of pasture. The area must be at least 

1.0 acre in size and 120.0 feet wide (USDA FS 2010). 

Bureau of Land Management

Land on which the indigenous vegetation (climax or natural potential) is predominantly grasses, grass-like plants, forbs, 

or shrubs and is managed as a natural ecosystem. If plants are introduced, they are managed similarly. Rangelands 

include natural grasslands, savannas, shrublands, many deserts, tundra, alpine communities, marshes, and wet 

meadows (Society for Range Management 1998).

Natural Resources Conservation Service

A land cover/use category that includes land on which the climax or potential plant cover is composed principally of 

native grasses, grass-like plants, forbs or shrubs suitable for grazing and browsing, and introduced forage species that 

are managed like rangeland. This would include areas where introduced hardy and persistent grasses, such as crested 

wheatgrass, are planted and practices such as deferred grazing, burning, chaining, and rotational grazing, are used 

with little or no chemicals/fertilizer being applied. Grasslands, savannas, many wetlands, some deserts, and tundra are 

considered to be rangeland. Certain low forb and shrub communities, such as mesquite, chaparral, mountain shrub, 

and pinyon-juniper, are also included as rangeland (USDA 2009).
276 USDA Forest Service RMRS-GTR-374. 2018

influences such as fire regimes and periodicity of precipitation. Understanding resistance and resilience for rangelands 

is important for estimating possible effects of climate 

change. In broad terms, resilience refers to the capacity of 

ecosystems to regain structure, processes, and functioning in response to disturbance (Allen et al. 2005; Holling 

1973), whereas resistance describes capacity to retain these 

community attributes in response to disturbance (Folke et 

al. 2004). These concepts are especially critical when considering establishment of nonnative plants and interactions 

between climate change stressors (Chambers et al. 2014). 

In the Northern Rockies region, areas with higher precipitation and cooler temperatures generally result in greater 

resources and more favorable conditions for plant growth 

and reproduction (Alexander et al. 1993; Dahlgren et al. 

1997). These concepts are demonstrated in fig. 7.1, which 

indicates that management for ecosystem services derived 

from rangelands will be relatively more effective in more 

mesic rangelands.

In this chapter we explore potential effects of climate 

change on selected rangeland habitats. The evaluation of 

risk was qualitatively and synthetically determined by using 

a combination of workshop output, literature (where available), and the judgment of the authors and two reviewers. It 

is meant to represent our best guess as to the relative vulnerability of each system to estimated perturbations brought 

forth by expected changes in climate across the Northern 

Rockies region.

Vegetation Classes

The rangeland assessment focuses largely on groupings 

of vegetation types but also references individual species 

where information and data suggest inferences can be 

made for species. We identified rangeland vegetation to be 

included in the vulnerability assessment by first reviewing 

the extent of rangelands within the conterminous United 

States (Reeves and Mitchell 2011). The National Resources 

Inventory definition (box 7.1) of rangelands was used to 

identify rangelands within the Northern Rockies region. The 

list of U.S. Ecological Systems designated as rangelands 

that were retained for evaluation is found in table 7.1. The 

great complexity of rangeland vegetation combined with 

a paucity of studies on climate change effects suggests 

that a grouping of individual vegetation types into classes 

would be useful. The resulting groups to be analyzed are 

the northern Great Plains, montane shrubs, montane grasslands (referred to as “western grasslands”), and sagebrush 

systems. It is important for the reader to understand that 

multiple vegetation types make up each of the four broad 

classes of vegetation. In the case of sagebrush systems, 

however, four groups (big sagebrushes, short sagebrushes, 

sprouting sagebrushes, and mountain sagebrush) were subsequently further permuted by individual types (table 7.1).

The northern Great Plains has a broad geographic 

expanse and mixture of both cool-season (C3) and 

warm-season (C4) species. Montane shrubs are species important for browsing by native ungulates. The relatively rare 

montane grasslands have a unique position on the landscape, 

dominance of cool-season species, and specific types of 

habitats they provide in juxtaposition to forest vegetation.

Sagebrush systems (dominated by species in the genus 

Artemisia) provide critical wildlife habitat, including for 

the imperiled greater sage-grouse, and are a ubiquitous and 

iconic species in much of the western United States. In addition, sagebrush systems, especially those dominated by 

big sagebrushes, have been more widely studied, at least 

partially as a result of recent research on sage-grouse habitat. Therefore, the vulnerability of some sagebrush species 

is supported by a richer body of information than for other 

vegetation. But this does not mean that all sagebrush types 

have been studied equally in the context of climate change. 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region

Figure 7.1—Resilience to disturbance (a) and resistance to 

cheatgrass (b) over a typical temperature/precipitation 

gradient in the cold desert. Dominant ecological sites occur 

along a continuum that includes Wyoming big sagebrush 

on warm and dry sites, to mountain big sagebrush on 

cool and moist sites, to mountain big sagebrush and 

root-sprouting shrubs on cold and moist sites. Resilience 

increases along the temperature/precipitation gradient and 

is influenced by site characteristics like aspect. Resistance 

also increases along the temperature/precipitation 

gradient and is affected by disturbances and management 

treatments that alter vegetation structure and composition 

and increase resource availability. ARTRw = Wyoming big 

sagebrush (Artemisia tridentata ssp. wyomingensis); ARTRv 

= mountain big sagebrush (A. tridentata ssp. vaseyana); 

SYOR = mountain snowberry (Symphoricarpos oreophilus) 

(modified from Chambers et al. 2014).
USDA Forest Service RMRS-GTR-374. 2018 277

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region

Table 7.1—Aproximate area of U.S. Ecological Systems identified as rangelands within the NRAP assessment region. Sagebrush 

systems were further subdivided into mountain, low, and big or sprouters. These distinct species were grouped into the “big 

or sprouters” category only for developing map legends because, using the mid-level Ecological Systems mapping approach, 

without external data, it would be difficult to differentiate each unique cover type dominated by the various Artemisia spp. 

across the landscape. 

Rangeland vegetation types Ecological system Area

Sagebrush 

grouping

Acres

Northern Great Plains (C3/C4 mix) Central Tallgrass Prairie 479,899 NA

Northwestern Great Plains Mixedgrass Prairie 37,818,629 NA

Western Great Plains Sand Prairie 2,285,234 NA

Western Great Plains Shortgrass Prairie 39,543 NA

Western Great Plains Tallgrass Prairie 7,763 NA

North-Central Interior Sand and Gravel Tallgrass 

Prairie

209,599 NA

Northern Tallgrass Prairie 367,864 NA

Great Plains Prairie Pothole 262,813 NA

Total 41,471,344 NA

Montane shrubs Northern Rocky Mountain Montane-Foothill 

Deciduous Shrubland

1,257,671 NA

Inter-Mountain Basins Curl-leaf Mountain 

Mahogany Woodland and Shrubland

175,887 NA

Rocky Mountain Lower Montane-Foothill Shrubland 4,602 NA

Total 1,438,160 NA

NA

Montane grasslands (C3) Columbia Plateau Steppe and Grassland 1,257,642 NA

Columbia Basin Palouse Prairie 2,692,161 NA

Columbia Basin Foothill and Canyon Dry Grassland 58,773 NA

Inter-Mountain Basins Semi-Desert Grassland 42,311 NA

Northern Rocky Mountain Lower Montane-FoothillValley Grassland14,419 NA

Northern Rocky Mountain Subalpine-Upper 

Montane Grassland

5,957 NA

Total 4,071,263 NA

Sagebrush systems Artemisia tridentata ssp. vaseyana Shrubland 

Alliance

2,931,640 Mountain

Inter-Mountain Basins Big Sagebrush Steppe 9,656,339 Big or sprouter

Inter-Mountain Basins Big Sagebrush Shrubland 2,451,624 Big or sprouter

Inter-Mountain Basins Montane Sagebrush Steppe 1,993,178 Big or sprouter

Columbia Plateau Low Sagebrush Steppe 156,012 Low

Wyoming Basins Dwarf Sagebrush Shrubland and 

Steppe

49,723 Low

Inter-Mountain Basins Semi-Desert Shrub-Steppe 41,572 Big or sprouter

Great Basin Xeric Mixed Sagebrush Shrubland 17,970 Low

Columbia Plateau Scabland Shrubland 14,529 Big or sprouter

Total 17,312,587

All rangelands total 64,293,354
278 USDA Forest Service RMRS-GTR-374. 2018

To reflect the disparate amount of study on climate change 

effects on sagebrush species, four sagebrush types were 

delineated for the Northern Rockies for this study (fig. 7.2, 

sagebrush types):

• Big sagebrushes: Wyoming big sagebrush (A. 

tridentata spp. wyomingensis) and basin big sagebush 

(A. tridentata ssp. tridentata)

• Low sagebrushes: low sagebrush (A. arbuscula) and 

black sagebrush (A. nova)

• Sprouting sagebrushes: silver sagebrush (A. cana) and 

threetip sagebrush (A. tripartita)

• Mountain big sagebrush (A. tridentata ssp. vaseyana)

Figure 7.2 does not represent an exact accounting of 

these four vegetation classes but suggests an estimated distribution where each grouping is usually found. In addition, 

when Ecological Systems are mapped at this level, it is not 

possible to differentiate the distribution of silver and threetip 

sagebrush as they are often disjunctively commingled with 

other types. As a result, only three categories are mapped; 

within the largest category, the big sagebrushes and 

sprouting sagebrushes are all represented in one estimated 

distribution.

The Wyoming and basin big sagebrush types were aggregated because they have similar life histories, stature, 

and areal coverage in the Northern Rockies region, and 

represent critical habitats for many species of birds and wild 

and domestic ungulates. Despite similar life history traits, 

basin big sagebrush occupies sites with deeper soils (often 

on alluvial fans). These conditions tend to increase available 

moisture with higher coverage by perennial bunchgrasses, 

suggesting these sites may be more resilient and resistant to 

various threats (Chambers et al. 2007). Similarly, the low 

sagebrushes were chosen for the unique habitats they represent (especially black sagebrush) and similar life histories. 

Both silver sagebrush and threetip sagebrush can resprout 

after fire, making them unique in that regard among the 

sagebrush species, with the exception of periodic sprouting 

by some variants of mountain big sagebrush.

Finally, mountain big sagebrush was chosen for its 

(usually) distinct positioning on the landscape, in addition to being the most mesic of sagebrush communities 

in the Northern Rockies region. Communities dominated 

by Wyoming big sagebrush are by far the most common 

and occupy the greatest area (table 7.2), whereas the low 

sagebrush type occupies the least. However, although basin 

and Wyoming big sagebrush are common throughout the 

Northern Region, mountain big sagebrush communities 

occupy the greatest extent on lands managed by the USFS. 

Although the communities dominated by the Artemisia

species listed here were subdivided for evaluating possible 

effects of climate change, four species (basin big, Wyoming 

big, threetip, and silver) were grouped for mapping purposes 

as the “big or sprouter” category (table 7.1) because differentiating them across the landscape was impractical.

Vegetation Productivity in 

Response to Climate Change

Although the current extent of rangeland in the Northern 

Rockies region can be accurately described, uncertainty in 

Figure 7.2—Estimated 

distribution of various 

sagebrush vegetation classes 

in the Northern Rockies.

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 279

Table 7.2—Area of rangeland vegetation classes evaluated in each NRAP subregion.

Subregion Rangeland vegetation classes Area Proportion

Acres Percent

Western Rockies Montane grasslands 596,837 34.4

Montane shrubs 298,153 35.7

Sagebrush systems 358,086 29.9

Total 1,253,076

Central Rockies Montane grasslands 845,539 43.6

Montane shrubs 173,980 18.6

Sagebrush systems 507,391 37.8

Total 1,526,909

Eastern Rockies Montane grasslands 735,758 13.5

Montane shrubs 328,306 12.5

Northern Great Plains (C3/C4 mix) 221,193 5.9

Sagebrush systems 2,572,138 68.2

Total 3,857,395

Grassland Montane grasslands 1,343,858 1.8

Montane shrubs 266,233 0.7

Northern Great Plains (C3/C4 mix) 41,204,297 80.6

Sagebrush systems 8,586,897 16.8

Total 51,401,285

Greater Yellowstone 

Area Montane grasslands 549,271 6.1

Montane shrubs 371,488 8.5

Northern Great Plains (C3/C4 mix) 45,848 0.7

Sagebrush systems 5,288,075 84.7

Total 6,254,682

All subregions total 128,586,695

the underlying global climate models (GCMs) used to estimate climate change effects (see Chapter 3), and uncertainty 

in models of physiological response, make it difficult to confidently project the effects of climate change on rangelands. 

Our understanding of the potential effects of climate change 

in the region can be improved if comparisons of impacts are 

made with other areas.

The primary inference about climate change effects 

on rangeland vegetation nationally is one of increasing 

temperature, lower soil moisture, changing phenology, and 

decreasing annual production. However, projected temperatures exhibit far less variability among scenarios and GCMs 

than precipitation. Therefore, areas where projections suggest that temperature rather than precipitation is a dominant 

driver may be more reliable. Figure 7.3 suggests that, relative to much of the rest of the United States, the Northern 

Rockies region could experience an increase in annual net 

primary productivity (NPP). In addition, the modeled overall increases in productivity appear to be more consistent in 

the region compared with other areas because there is less 

disagreement among the three emissions scenarios evaluated 

(Nakićenović et al. 2000; Reeves et al. 2014).

Changing climate regimes will also influence phenology 

in unexpected ways. For example, in tallgrass prairie (a rare 

type in the Northern Rockies region), a 7.2 °F increase in 

ambient temperature caused earlier anthesis among springblooming species and later anthesis in fall-blooming species 

(Sherry et al. 2007), implying that climate change will 

influence vegetation in complex ways (Suttle et al. 2007; 

Walther 2010). In addition, effects of climate change may be 

greater at higher elevations (Beniston et al. 1997) (fig. 7.3), 

a logical projection for the Northern Rockies region, where 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
280 USDA Forest Service RMRS-GTR-374. 2018

Figure 7.3—Mean slope of linear regression of the net primary productivity trend for the B2, A1B, and A2 emission 

scenarios (models averaged here include: GCGM2, HadCM3, CSIRO, MK2, MIROC3.2) (a) and standard 

deviation of the mean slope of linear regression of the net primary productivity trend for the same scenarios (b) 

(from Reeves et al. 2014).

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 281

the primary factor limiting plant growth at high elevations is 

growing season length and cold temperatures.

The modeled overall effect of projected climate change 

in the Northern Rockies region is apparently increased 

growing season length and increased NPP, which may be 

especially pronounced at higher elevations. Removal of 

growth limitations could result in significant changes in vegetation at higher elevations, such as the Greater Yellowstone 

Area subregion. Higher NPP may seem counterintuitive because increased temperatures suggest greater moisture stress 

and therefore potentially less favorable growing conditions. 

Indeed, if all other factors besides temperature remained 

constant in the future, then vegetation might undergo significant reductions in productivity from increased evaporative 

demand and reduced soil moisture. Conversely, some highelevation areas may experience increased production with 

increasing temperatures (Reeves et al. 2014), especially 

relatively mesic areas supporting mountain sagebrush.

Increased atmospheric carbon dioxide (CO2) concentrations may modify ecophysiological growth processes in 

rangeland vegetation. Carbon dioxide enrichment can 

enhance water use efficiency through reduced water lost 

through stomata (see Chapter 6), but the response is not 

consistent across all vegetation. For example, in tallgrass 

prairie, Owensby et al. (1999) found that elevated CO2

could increase productivity of aboveground and belowground biomass, but response depended on water stress. 

These findings are consistent with results from Reeves et 

al. (2014) and suggest that desiccation effects of increased 

temperature can be offset to some extent by CO2 enrichment 

via reduced transpirational demand (Leakey 2009; Morgan 

et al. 2004b, 2011; Woodward and Kelly 2008) and higher 

water use efficiency (Bachelet et al. 2001; Christensen et al. 

2004; Morgan et al. 2008, 2011; Polley et al. 2003).

Recent experimental research on the northern Great 

Plains is particularly relevant to the managers in the 

Grassland subregion where northern mixed-grass prairie 

dominates. The Prairie Heating and CO2 Enrichment 

(PHACE) study reported an increase of aboveground productivity by an average of 33 percent over 3 years (Morgan 

et al. 2011), which substantiates estimates by Reeves et al. 

(2014) of a 28-percent increase in productivity for the northern Great Plains by 2100.

As a footnote to the preceding discussion, it is important 

to note that all models are a simplification of reality, and 

interpretation of model results needs to consider uncertainty, 

inputs, and model assumptions. Models cited here have increasing disparity as time progresses, especially in more arid 

regions where changing precipitation amounts and patterns 

may be the primary driver of change.

Management Concerns

The primary management and ecological concerns identified as affecting rangelands in the Northern Rockies region 

include uncharacteristic fire regimes, improper grazing, and 

invasive species. Uncharacteristic fire regimes, which are 

based on the historical fire regime, threaten some rangeland 

habitats, especially sagebrush steppe, across much of the 

western United States, including the Northern Rockies region. The overall concern over uncharacteristic fire regimes 

is perhaps smaller than for other regions such as the Great 

Basin. On one end of the spectrum, the shortened fire return 

intervals of many sagebrush habitats suggest that “too 

much” fire currently affects the landscape relative to historical fire regimes. It is widely documented that increasing 

dominance of invasive annual grasses has created a positive 

feedback cycle characterized by frequent fire followed by 

increased dominance of annual grasses, which further create fuel conditions that facilitate combustion (Chambers et 

al. 2007). These conditions are exacerbated by wetter and 

warmer winters, which are projected throughout the region 

in the future.

On the other end of the spectrum, fire exclusion has led 

to decreased fire return intervals, which may be responsible 

for Douglas-fir (Pseudotsuga menziesii) encroachment into 

montane grasslands (Arno and Gruell 1986), and into higher 

elevation sagebrush habitats, especially those dominated by 

mountain big sagebrush (Heyerdahl et al. 2006) (fig. 7.4). 

Overall, the invasive species of greatest concern in sagebrush communities throughout Northern Rockies rangelands 

is cheatgrass (Bromus tectorum), although Japanese brome 

(B. japonicus) and leafy spurge (Eurphorbia esula) are also 

concerns in the northern Great Plains. Recent range expansion of cheatgrass is particularly prominent in the western 

half of the Northern Rockies region and can be somewhat 

explained by genetic variation leading to increased survival 

and persistence in otherwise marginal habitats (Merrill 

et al. 2012; Ramakrishnan et al. 2006). This rapid range 

Figure 7.4—Conifer encroachment, predominantly ponderosa 

pine into a montane grassland, including the ubiquitous 

graminoid rough fescue (photo: Mary Manning, USDA 

Forest Service).

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
282 USDA Forest Service RMRS-GTR-374. 2018

expansion may be enhanced by elevated atmospheric CO2

concentrations and increased soil disturbance (Chambers 

et al. 2014). Improper grazing, a term referring to the mismanagement of grazing that produces detrimental effects on 

vegetation or soil resources, can exacerbate these conditions 

(see chapter 6). Generally, however, U.S. rangelands are 

not improperly grazed (Reeves and Bagget 2014; Reeves 

and Mitchell 2011) to the point of degradation; improper 

grazing is not the normal condition across rangelands in the 

Northern Region. Where improper grazing does occur, it can 

accelerate the annual grass invasion/fire cycle, especially 

in some sagebrush types, the northern Great Plains, and 

montane grasslands.

Broad-Scale Vulnerability of 

Rangelands to Climate Change

Determining the vulnerability of rangeland vegetation 

is a difficult task. Uncertainty exists in the projections of 

future climatic conditions as well as in expected effects of 

vegetation. Given the lack of studies focused on manipulated climate on vegetation performance, we are limited to 

past observations, some published scientific studies, and our 

collective best judgment. Despite the paucity of relevant 

studies and the uncertainty of projected climates, a few 

elements of climate change are increasingly recognized as 

potential outcomes. In this section, we briefly discuss some 

overarching expected climatic conditions against which we 

estimate likely outcomes for vegetation in each of the four 

identified vegetation classes.

Projected temperature increases (Intergovernmental 

Panel on Climate Change [IPCC] 2014; see also Capter 

3) are expected to increase evaporative demand (e.g., 

potential evapotranspiration) (Klos et al. 2014) and pose 

the greatest overall temperature stress of all the estimated 

future climate outcomes (Polley et al. 2013). Projected 

changes in precipitation patterns and increasing potential 

evapotranspiration could encourage more frequent and 

intense fires from the effects of early-season plant growth 

combined with the desiccating effects of warmer, drier summers (Morgan et al. 2008). Collectively, these changes may 

result in considerably drier soils, particularly in the summer 

months when plants are phenologically active (Bradford et 

al. 2014; Polley et al. 2013). However, winter precipitation 

is projected to increase by 10 to 20 percent in the Northern 

Rockies region (IPCC 2014; Shafer et al. 2014; see also 

Chapter 3), which may compensate for increasing severity 

and frequency of droughts. In addition, rising CO2 levels 

may offset water loss due to higher evaporative demand by 

increasing stomatal closure and water use efficiency.

Warmer winters and decreasing snowpack may also be 

significant factors affecting rangeland vegetation classes 

(discussed next). Minimum temperatures are expected to 

increase more than maximum temperatures, providing 

longer frost-free periods. Warmer, wetter winters would 

favor early-season plant species and tap-rooted species that 

are able to reach accumulated early growing season soil 

water (Polley et al. 2013). These conditions are projected to 

significantly increase annual area burned and fire intensity 

(Westerling et al. 2006).

Northern Great Plains, Dominated by 

Mixtures of Cool-Season and WarmSeason Grasses

Eastern grasslands are expansive across the northern 

Great Plains, extending from the foothill grasslands along 

the east slope of the northern and central Rocky Mountains 

in Montana to the Red River basin in eastern North Dakota. 

Annual precipitation increases from west to east and ecological provinces change from dry temperate steppe to humid 

temperate prairie parkland along this gradient (Cleland et 

al. 2007). Grasslands are the predominant potential vegetation type, occupying about 80 percent of the northern Great 

Plains landscape. Küchler (1975) divides the potential 

natural vegetation of this area into shortgrass prairie, northern mixed grass prairie, and tallgrass prairie, reflecting the 

changing precipitation regime. The shortgrass prairie borders the foothill grasslands and extends to eastern Montana. 

The typical grassland vegetation types are characterized by 

grama (Bouteloua spp.)/needlegrass (Stipa spp.)/wheatgrass 

(Pseudoroegneria spp.) and a mix of C3 and C4 plant species. The northern mixed grass prairie borders the shortgrass 

prairie in eastern Montana and extends to eastern North 

Dakota. Typical grassland vegetation types are characterized 

by wheatgrass/needlegrass in the west and wheatgrass/bluestem (Andropogon spp.)/needlegrass to the east, including a 

mix of C3 and C4 plant species. The tallgrass prairie borders 

the northern mixed grass prairie in eastern North Dakota and 

South Dakota and borders the eastern hardwood forest to the 

east. The typical grassland vegetation types are characterized by bluestem and a dominance of C4 grasses, although 

C3 grass species are present.

Frequent fire was a major factor in maintaining grassland dominance, particularly in the eastern Great Plains. 

Settlement in the late 19th and early 20th centuries altered 

fire regimes by reducing fire frequency and changing the 

seasonality of fire. The predominant land use and land cover 

changed from grasslands to crop agriculture and domestic 

livestock production, affecting the continuity of fuels and 

fire spread. Reduced fire coupled with increased CO2 has 

encouraged woody plant encroachment, primarily in the 

eastern Great Plains (Morgan et al. 2008).

Other stressors include increased presence and abundance of competitive invasive grass and forb species. 

These species reduce plant diversity of native grasslands 

and alter grassland structure. Noxious weeds such as leafy 

spurge (Euphorbia esula) are abundant in places, and other 

invasive nonnative species include Kentucky bluegrass (Poa 

pratensis), Japanese brome, and cheatgrass. In addition, 

energy development and the associated infrastructure fragments local grassland patterns where it occurs. Roads and 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 283

traffic increase opportunities for introduction and spread of 

invasive species.

Soil water availability and water stress are principal 

driving factors in semiarid grasslands, influencing plant 

species distribution, plant community composition and 

structure, productivity, and associated social and economic 

systems of the northern Great Plains. Soil water availability 

is influenced by complex interactions among temperature, 

precipitation, topography, soil properties, and ambient CO2

(Ghannoum 2009; Morgan et al. 2011). These physical 

factors interacting with plant species physiological mechanisms, particularly those of C3 and C4 plants, will influence 

how grasslands will respond to climate change and elevated 

atmospheric CO2 levels (Bachman et al. 2010; Chen et al. 

1996; Ghannoum 2009; Morgan et al. 2011).

Available soil water is unevenly distributed across 

landscapes and is a function of landform, topography, and 

soil properties. Soil moisture loss through evapotranspiration is influenced by slope, aspect, and solar loading at the 

ground surface, and water holding capacity is influenced by 

soil properties. These characteristics in the northern plains 

may modify the effects of climate change and enhanced 

CO2 locally. Landscape patterns of available soil water may 

result in uneven patterns of vegetation change and productivity under changing temperature and moisture regimes 

and elevated CO2 levels. The desiccating effect of higher 

temperature and increased evaporative demand (Morgan et 

al. 2011) is expected to offset the benefit of higher precipitation, resulting in lower soil water content and increased 

drought throughout most of the Great Plains (Morgan et 

al. 2008). Elevated CO2 may counter the effects of higher 

temperatures and evaporative demand by improving water 

use efficiency of plants (Morgan et al. 2011).

Rising CO2 and temperature combined with increased 

winter precipitation may favor some herbaceous forbs, 

legumes, and woody plants (Morgan et al. 2008). Plant 

productivity is expected to increase with projected changes 

in temperature and moisture combined with elevated CO2

(Morgan et al. 2008). Forage quality may decline as a result 

of less available forms of soil nitrogen and changes in plant 

species and functional groups (Morgan et al. 2008). A major 

shift in functional groups from C3 to C4 plants is possible 

but uncertain; warmer temperature and longer growing 

seasons favor C4 grasses, but the effects of higher CO2 on 

water-use efficiency may benefit C3 grasses. Most invasive 

species are C3 plants, so they may become more problematic with the benefits of increased CO2 (Morgan et al. 2008).

The adaptive capacity of Great Plains grasslands during 

the drought of the 1930s and 1950s was documented for 

the central plains (Weaver 1968). There was a shift in C4 

grasses, in which big bluestem (Andropogon gerardii) and 

little bluestem (Schizachyrium scoparium) were replaced by 

the shortgrass species blue grama (Bouteloua gracili) and 

buffalograss (B. dactyloides). Shifts from tallgrass prairie to 

mixed grass prairie were also documented with an increase 

in the C3 plants western wheatgrass and needlegrass. This 

shift was later reversed during the higher precipitation 

period of the 1940s, indicating historical adaptive capacity of Great Plains grasslands to the effects of long-term 

drought. These shifts were also affected by grazing condition of the grasslands before the drought.

Risk Assessment

Magnitude of effects: Moderate magnitude for change 

from temperate grassland to subtropical grassland by 2050 

under no fire suppression. Change toward increased woody 

vegetation by 2050 with fire suppression. High magnitude for change from temperate grassland to subtropical 

grassland by 2100. Moderate magnitude for change toward 

woody vegetation by 2100.

Likelihood of effects: Moderate likelihood for change 

from temperate grassland to subtropical grassland by 2050 

with no fire suppression, and moderate likelihood for change 

to increased woody vegetation by 2050 with fire suppression. The response of C3 and C4 species to the combined 

effects of higher temperature and elevated CO2 is uncertain.

Communities Dominated by Montane 

Shrubs

Montane shrubs are typically associated with montane 

and subalpine forests, and occur as large patches within 

forested landscapes. Species such as Rocky Mountain 

maple (Acer glabrum), oceanspray (Holidiscus discolor), 

tobacco brush (Ceanothus velutintis var. velutinus), Sitka 

alder (Alnus viridus subsp. sinuata), thimbleberry (Rubus 

parviflorus), chokecherry (Prunus virginiana), serviceberry 

(Amelanchier alnifolia), currant (Ribes spp.), snowberry 

(Symphoricarpos albus), Scouler willow (Salix scouleriana), and mountain ash (Sorbus scopulina) are common.

Montane shrubs persist on sites where regular disturbance kills the top of plants. This, along with full sunlight 

and adequate soil moisture, stimulates regrowth from the 

root crown, rhizomes, and roots. Stressors include fire 

exclusion and conifer establishment, browsing by both 

native and domestic wildlife, and insects and disease. Loss 

of topsoil following frequent, hot fires, can lead to loss of 

these species over time (Larsen 1925; Wellner 1970). Mesic 

shrubs are well adapted to frequent fire, and under the 

right conditions can expand and outcompete regenerating 

conifers. However, with declining snowpack and warmer 

temperatures, fires may be hotter and sites may be drier, 

causing variable amounts of mortality, depending on site 

conditions.

Mesic shrubs are well adapted to frequent fire (Smith 

and Fisher 1997) and sprout vigorously after fire, enabling 

them to quickly regain dominance on the site. As sites 

become drier and fires become more frequent and severe, 

however, there may be a shift away from mesic species to 

more xeric species such as rubber rabbitbrush (Ericameria 

nauseosa), green rabbitbrush (Chrysothamnus viscidiflorus), and spineless horsebrush (Tetradymia canescens). 

Nonnative invasive plant species may also expand into these 

communities, particularly following fire (Bradley 2008; 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
284 USDA Forest Service RMRS-GTR-374. 2018

D’Antonio and Vitousek 1992). With warmer temperatures 

and drier soils, some mesic shrub species (e.g., Sitka alder 

and Rocky Mountain maple) may shift their distribution up 

in elevation or to cooler, moister sites (e.g., northeast-facing 

depressions).

Risk Assessment

Magnitude of effects: Moderate

Likelihood of effects: High

Montane Grasslands

Montane grasslands are associated with mountainous portions of the Northern Rockies region including 

the Palouse prairie and canyon grasslands of northern and 

central Idaho. Montane grasslands occur in intermountain 

valleys, foothills, and mountain slopes from low to relatively high elevation. They are dominated by C3 grasses, along 

with a large number of forbs and upland sedges. Shrubs and 

trees may occur with low cover. Dominant species include 

bluebunch wheatgrass (Pseudoroegneria spicata), rough 

fescue (Festuca campestris), Idaho fescue (F. idahoensis), 

Sandberg bluegrass (Poa secunda), needle-and-thread 

(Hesperostipa comata), western wheatgrass (Pascopyrum 

smithii), prairie junegrass (Koeleria macrantha), western 

needlegrass (Achnatherum nelsonii), and Richardson’s 

needlegrass (A. richardsonii).

Many low-elevation grasslands have been converted to 

agricultural use or are grazed by domestic livestock. They 

have also been subjected to extensive human use and land 

use conversion. Those grasslands that remain, particularly at 

lower elevations, are typically highly disturbed, fragmented, 

and frequently occupied by many nonnative invasive plant 

species. Prolonged improper livestock grazing, native 

ungulate herbivory, and nonnative invasive plants are the 

primary stressors in these grasslands (Finch 2012). Loss of 

topsoil can occur if vegetation cover and density decline and 

bare ground increases. Lack of fire is also a chronic stressor 

because conifers from lower montane forests can become 

established in some areas, and can increase in density and 

cover with fire exclusion (Arno and Gruell 1986; Heyerdahl 

et al. 2006). As conifer density and cover increase with fire 

exclusion, grass cover declines because most grassland 

species are shade-intolerant (Arno and Gruell 1983). If 

fires become hotter and more frequent, however, there is an 

increased risk of mortality of native species and invasion by 

nonnative plant species. But invasive plants may not always 

establish and dominate a site (Ortega et al. 2012; Pearson et 

al., in review) under these conditions. If spring and winter 

precipitation increase, some expect exotic annual grasses, 

particularly cheatgrass, which germinates in the winter/early 

spring, to establish and set seed earlier than native perennial 

grasses (Finch 2012). This would create an uncharacteristic, 

continuous fine fuel load that is combustible by early summer and capable of burning native perennial grasses often 

before they have matured and set seed (Bradley 2008; 

Chambers et al. 2007). Other nonnative species, such as 

spotted knapweed (Centaurea melitensis), Dalmatian toadflax (Linaria dalmatica), butter-and-eggs (Linaria vulgaris), 

and sulphur cinquefoil (Potentilla recta) respond favorably 

after fire and can increase in cover and density.

Nonnative invasive plant species will probably expand, 

particularly in the lower elevation grassland communities, 

because resistance to invasion may decrease as these communities become warmer and drier (Chambers et al. 2014). 

Greater disturbance is likely to increase the rate and magnitude of infestation (Bradley 2008). In addition, drier site 

conditions coupled with ungulate effects (grazing, browsing, 

hoof damage) and the associated increases in surface soil 

erosion may increase bare ground (Washington-Allen et al. 

2010). Low-elevation grasslands may shift in dominance 

towards more drought-tolerant species. Some model output, 

such as MC2 (Bachelet et al. 2001) (see Chapter 6), suggests 

that C3 grasslands will decline and C4 grasslands will expand based solely on temperature trends. However, elevated 

CO2 favors C3 grasses and enhances biomass production, 

whereas warming favors C4 grasses due to increased water 

use efficiency (Morgan et al. 2004a, 2007). Although C3 

grasses dominate western montane grasslands, a warmer 

and drier climate may allow C4 grasses (primarily northern 

Great Plains species) to expand westward into montane 

grasslands. In general, it is likely that with increased 

warming and more frequent fires, grasslands will become 

a more dominant landscape component as shrublands and 

lower montane conifer forests are burned more frequently 

and unable to regenerate. Increasing fire would also lead to 

the expansion of invasive species into grasslands (Bradley 

2008; D’Antonio and Vitousek 1992).

Risk Assessment

Magnitude of effects: High

Likelihood of effects: High

Sagebrush Systems

Communities Dominated by Wyoming Big 

Sagebrush and Basin Big Sagebrush

The current distribution of Wyoming big sagebrush ecosystems in the Northern Rockies region is generally patchy 

throughout most of Montana with more spatially consistent 

cover in the Eastern Rockies and Grassland subregions 

(Comer et al. 2002). As previously mentioned, the distribution of basin big sagebrush habitats is generally restricted to 

deeper soils, often including alluvial fans. Stressors to both 

Wyoming and basin big sagebrush communities include 

prolonged improper livestock grazing, native ungulate 

herbivory, and nonnative invasive plants. Loss of topsoil 

can occur if vegetation cover and density decline and bare 

ground increases, primarily caused by ungulate impacts 

(e.g., grazing and mechanical/hoof damage). In contrast 

with mountain and basin big sagebrush habitats, Wyoming 

big sagebrush habitats spatially coincide with oil and gas 

development, which is prominent on the eastern edge of 

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USDA Forest Service RMRS-GTR-374. 2018 285

its distribution. The Grassland and Greater Yellowstone 

Area subregions contain the largest extent of these two big 

sagebrushes, although the Western Rockies subregion may 

contain the largest amount of basin big sagebrush.

Big sagebrush ecosystems have decreased in spatial extent 

in the 20th century (Bradley 2010; Knick et al. 2003; Manier 

et al. 2013; Noss et al. 1995) because of oil and gas development (Doherty et al. 2008; Walston et al. 2009), removal of 

big sagebrushes to increase livestock forage (Shane et al. 

1983), plant pathogens and insect pests (Haws et al. 1990; 

Nelson et al. 1990), improper grazing (Davies et al. 2011), 

invasive species (D’Antonio and Vitousek 1992; Davies 

2011), and changes in disturbance regimes (Baker 2011; 

Balch et al. 2013). Oil and gas development, along with urbanization and land conversion for agriculture and livestock 

grazing, lead not only to habitat loss, but to fragmented habitat patches (Naugle et al. 2011), resulting in barriers to plant 

dispersal, avoidance by greater sage-grouse, and loss of obligate and facultative wildlife species (Rowland et al. 2006). In 

addition to habitat destruction of big sagebrush ecosystems, 

several stressors can cause big sagebrush dieback and reduce 

its biomass and density, including insect pests (Haws et al. 

1990), plant pathogens (Cárdenas et al. 1997; Nelson et al. 

1990), and frost damage (Hanson et al. 1982). Improper use 

by domestic livestock alters the structure and composition 

of big sagebrush ecosystems through the loss of palatable 

components of the plant community (i.e., perennial grasses 

and forbs), along with reducing or increasing big sagebrush 

cover (Anderson and Holte 1981; Brotherson and Brotherson 

1981), and increasing the probability of nonnative annual 

grass invasion (Cooper et al. 2007; Davies et al. 2011; Knapp 

and Soulé 1996). Cheatgrass has reduced the spatial distribution and habitat quality of sagebrush ecosystems throughout 

much of the western United States (Balch et al. 2013; Brooks 

et al. 2004).

Invasion by cheatgrass will pose an even greater threat to 

big sagebrush ecosystems in the future because of projected 

increases in its biomass production and in fire frequency 

due to rising temperature and CO2 levels (Westerling et al. 

2006; Ziska et al. 2005). Although less studied, field brome 

(Bromus arvensis) can also negatively affect big sagebrush 

plant communities because it can colonize readily after 

stand-replacing fires that eliminate big sagebrushes (Cooper 

et al. 2007).

Several life history traits of big sagebrushes make them 

sensitive to direct and indirect effects of climate change. 

Amount and timing of precipitation control seeding establishment at low elevation, whereas minimum temperature 

and snow depth control germination and survival at high 

elevations (Nelson et al. 2014; Poore et al. 2009; Schlaepfer 

et al. 2014a). Drought events are projected to increase 

in the western United States in the future (IPCC 2014), 

although the likelihood of increased drought in the Northern 

Rockies Region is uncertain (see Chapter 3). Big sagebrush 

ecosystems remain vulnerable to drought, which may affect 

germination and survival of seedlings because soil water 

content primarily controls seedling survival (Schlaepfer et 

al. 2014a). Big sagebrush seedling survival may be highest in intermediate temperature and precipitation regimes 

(Schlaepfer et al. 2014b). Even after seedling establishment, 

drought and increased summer temperature can affect 

survival and growth of adult plants because growth is positively correlated with winter precipitation and winter snow 

depth (Poore et al. 2009). Thus, if drought events increase 

in frequency and severity in the Northern Rockies region, 

big sagebrush biomass and the abundance and diversity of 

perennial grasses and forbs may decrease.

It is uncertain if big sagebrush species can move in 

concert with shifting temperature and precipitation regimes 

and disperse to available habitat patches and colonize them. 

Most big sagebrush seeds (50–60 percent) are not viable in 

the seedbank after 2 years, with few viable seed in the upper 

soil (Wijayratne and Pyke 2009, 2012). Furthermore, big 

sagebrushes are poor dispersers (Schlaepfer et al. 2014a; 

Young and Evans 1989) and seed production is episodic 

(Young et al. 1989). Even if big sagebrush seeds successfully disperse and germinate in response to a changing 

climate, probabilities of seedling establishment and adult 

survivorship are uncertain because big sagebrushes are 

poor competitors relative to associated herbaceous species 

(Schlaepfer et al. 2014a).

Big sagebrushes are sensitive to fire and cannot resprout 

(Shultz 2006). Recovery from seed dispersal can take 50 to 

150 years (Baker 2006, 2011), so postfire recovery may become a problem in the future, if the frequency and intensity 

of fires increase as projected (Abatzoglou and Kolden 2011; 

Westerling et al. 2006). Regeneration of big sagebrushes 

postfire is strongly linked to winter precipitation (Nelson et 

al. 2014), which is expected to increase by 10 to 20 percent 

in the Northern Rockies region by 2100 (IPCC 2014; Shafer 

et al. 2014). Although more frequent fire may result in larger 

losses of big sagebrush habitat in the future, recovery of big 

sagebrushes may be less impeded. It is also possible that 

much of this increased precipitation will come as rainfall 

(Klos et al. 2014), which could, in turn, promote herbaceous 

growth that might suppress sagebrush recovery in some 

instances.

Climate change will result in shifts in the distribution of 

conditions suitable to support big sagebrushes and hence the 

spatial configuration of big sagebrush habitat, with direct 

and indirect effects on sagebrush-dependent species (e.g., 

greater sage-grouse). Several studies using species distribution modeling (SDM) have projected that big sagebrushes 

will move northward and up in elevation in response to 

increased winter temperatures and summer drought associated with climate change (Schlaepfer et al. 2012; Shafer 

et al. 2001). Although big sagebrush species may expand 

northward and upslope, their habitat is predicted to contract 

significantly due to increased soil moisture stress, primarily 

at southern latitudes and lower elevations (fig. 7.5).

The probability of big sagebrush regeneration has been 

projected to increase at the leading edge of their range (i.e., 

northern range limit) under future climatic conditions, suggesting potential northward range expansion with climate 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
286 USDA Forest Service RMRS-GTR-374. 2018

change (Schlaepfer et al. 2015). This is in part due to changes in habitat suitability because soil water conditions at the 

leading edge will be similar to current soil water patterns in 

big sagebrush systems. Habitat suitability for big sagebrush 

species is predicted to increase primarily in northeastern and 

north-central Montana (Schlaepfer et al. 2015; Schrag et al. 

2011) (fig. 7.5). In contrast, habitat suitability is predicted to 

decrease in parts of the Western Rockies and northwestern 

Greater Yellowstone Area subregions (fig. 7.5), primarily 

from summer drought (Schlaepfer et al. 2012; Schlaepfer et 

al, in review). However, expansion of big sagebrush species 

out of unsuitable habitat and into suitable habitat is contingent on the ability of the species to disperse to available 

habitat patches and compete with other species.

In addition to changes in big sagebrush distribution, 

shifts in community composition and productivity are 

expected with climate change. Because of the uncertainty 

about length and severity of drought events in the future, the 

projected shifts in community composition and productivity 

in big sagebrush ecosystems in response to climate change 

remain uncertain. If drought events do increase in the 

Northern Rockies region, native herbaceous plant diversity 

and cover may be reduced. In contrast, in nondrought years, 

warming temperatures and increased levels of CO2 may 

lead to increased biomass production (Reeves et al. 2014), 

more frequent fires, and increases in herbaceous biomass at 

the expense of fire-intolerant shrubs, such as big sagebrush 

species.

Paleoecological studies have shown that species move individualistically and at different rates in response to climate 

change, resulting in novel combinations of species (Delcourt 

and Delcourt 1981). Even species in the same functional 

group (e.g., grasses) may respond differentially to climate 

change (Anderson and Inouye 2001). Thus, big sagebrush 

plant communities are unlikely to migrate as a unit in 

response to altered temperature and precipitation. The 

response of individual species to climate change will depend 

on both physiological tolerances and competitive ability.

Shifts in disturbance regimes (e.g., fire, insects, 

pathogens) associated with climate change may affect big 

sagebrush ecosystems in the future. Disturbances affect 

vegetation directly by killing individuals and removing 

aboveground biomass, and indirectly by altering soil conditions. Climate change and disturbance may have additive 

effects on soil water balance in big sagebrush ecosystems, 

decreasing soil water content (Bradford et al. 2014) and 

resulting in diminished growth and regeneration (Poore et 

al. 2009). Increased disturbance frequency could reduce 

the spatial extent of big sagebrush in the future, despite 

increased habitat suitability and regeneration potential, 

because big sagebrush is incapable of resprouting after 

disturbance (Shultz 2006). As with other vegetation types, 

Figure 7.5—Mean and standard deviation of percent of subregions burned across three time spans (historic, 2030–2050, 

2080–2100) and without/with fire suppression.

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 287

there is great uncertainty and variability regarding estimates 

of fire return intervals of stands dominated by big sagebrush 

species. For example, in the Northern Rockies, Lesica et 

al. (2007) suggest that fire return intervals for Wyoming 

big sagebrush are longer than for basin big sagebrush and 

mountain big sagebrush, and range from 50 to 150 years, 

whereas Baker (2011, 2013) and Bukowski and Baker 

(2013) estimate ranges of 200 to about 350 years.

The long fire return intervals to which Wyoming big 

sagebrush is adapted are related to its very slow postfire 

recovery, as low as 2 percent recovery 23 years after fire 

(Lesica et al. 2007). The slow recovery of these systems is 

partly due to slow growth rates and harsher environmental 

conditions in many sites in the Northern Rockies region. 

Basin big sagebrush canopy cover development and growth 

are faster than for Wyoming big sagebrush (Booth et al. 

1990; Lesica et al. 2007; McArthur and Welch 1982). 

Invasive annual grasses such as cheatgrass may exacerbate 

slow growth.

Big sagebrush ecosystems have some capacity to adapt 

to climate change. Big sagebrush species occur over a large 

geographic area with high diversity in topography, soils, and 

climate, suggesting that these species can withstand a relatively broad range of ecological conditions and may tolerate 

shifting climates. Various subspecies of big sagebrush often 

hybridize and have a high level of polyploidy, providing them 

with the capacity to undergo selection and adapt to shifting 

climatic regimes relatively quickly (e.g., Poore et al. 2009).

Although lower soil water availability may pose a threat 

to big sagebrush ecosystems, long periods of sustained 

drought would be needed to cause mortality (Kolb and 

Sperry 1999). Even though big sagebrush habitat suitability is projected to change across space (e.g., decreasing 

suitability in northwestern Wyoming and across much of 

western Montana), big sagebrush species may still persist in 

relatively “unsuitable” habitat for some time, perhaps in a 

degraded state.

Risk Assessment

Magnitude of effects: Highly variable. In northwestern 

Wyoming and western Montana, the effects of climate 

change are likely to be low to moderate. Lower water availability may cause declines in big sagebrush growth and 

regeneration, facilitating some habitat contraction. However, 

big sagebrush species may expand northward into northern 

and eastern Montana, as habitat suitability increases in future decades. Despite this generalization, it is also possible 

that an increase in fire activity will decrease the extent of 

big sagebrush communities in many locations.

Likelihood of effects: Variable. Some contraction in big 

sagebrush habitat may occur in northwestern Wyoming and 

western Montana, particularly at lower elevations, because 

of increased temperature and evapotranspiration. However, 

if big sagebrush can successfully exploit changing climatic 

conditions, the total area covered by big sagebrush species 

in the Northern Rockies region may increase by the end of 

the 21st century. Potential expansion may be tempered by 

faster rates of loss if the cheatgrass-fire cycle tracks new 

habitats in the northeastern part of the region. It is conceivable that drier sites, such as those with sandy soils, may lose 

the ability to regenerate sagebrush, whereas more mesic 

sites might still be able to regenerate.

Communities Dominated by Low Sagebrushes 

(Black and Low Sagebrush)

The current distribution of low sagebrush ecosystems in 

the Northern Rockies region is restricted to about 1 percent 

of the total sagebrush habitat as indicated in the LANDFIRE 

existing vegetation type (EVT) database. The western portion of the Northern Rockies region contains 50 percent 

of the low sagebrush habitat, but limited patches are also 

found in the Eastern Rockies subregion and in the Greater 

Yellowstone Area subregion, especially on the western edge. 

Most of these sites support low sagebrush but not black 

sagebrush. Low sagebrush sites are characterized as relatively low-production areas over shallow, claypan soils that 

restrict drainage and root growth. Low sagebrush is found 

on altitudinal gradients from 2,300 feet to more than 11,500 

feet (Beetle and Johnson 1982), and it is generally found 

between 6,000 and 9,000 feet in Montana and Idaho. In 

contrast, black sagebrush is considerably more restricted in 

ecological amplitude and is found on shallow, dry, infertile 

soils. Current stressors are predominantly improper use by 

livestock and invasion by nonnative species.

Despite growing across a broad range of elevations, low 

and black sagebrush are less common than other sagebrush 

species. Thus, it is reasonable to assume that as climates 

change, ranges could be further restricted, resulting in small 

islands being isolated, although this is more likely for black 

sagebrush because of its poor competitive ability (West and 

Mooney 1972). Both species depend heavily on seeding 

for reproduction (Wright et al. 1979) and recovery from 

disturbance. In addition, several traits make low sagebrush 

species sensitive to climate change. There is high mortality in the first year of growth (Shaw and Monsen 1990). 

Establishment is probably greatest when a thin layer of soil 

covers the seeds, and if erosion increases from droughtinduced reductions of plant cover, the already thin soils 

may not provide suitable seedbeds for germination. Seed 

development and establishment are best in years with ample 

precipitation, and if unfavorable conditions for seeding 

persist following disturbance, it is reasonable to assume that 

low sagebrush species may disappear from some stands, especially if annual grass invasion occurs concomitantly with 

unfavorable growth conditions.

Climate change will result in shifts in the distribution of 

conditions suitable to support low sagebrush species and 

hence the spatial configuration of low sagebrush habitats. 

Both low and black sagebrush are intolerant of fire and do 

not resprout. Therefore, increased fire activity will have 

negative consequences for both species. Fire return intervals 

vary considerably among communities dominated by low 

sagebrush species. Estimates of fire return intervals for xeric 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
288 USDA Forest Service RMRS-GTR-374. 2018

sagebrush communities of the Great Basin range from 35 

to more than 100 years (Brown 2000; Riegel et al. 2006), 

but intervals of 100 to 200 years for low-productivity black 

sagebrush communities have been reported. Especially for 

black sagebrush, which usually occupies quite unproductive 

sites with small buildup of fuels, these fire return intervals 

may be overestimated (Baker 2013). Within the boundaries 

and on the periphery of the Greater Yellowstone Area subregion, MC2 results indicate that the proportion of landscape 

burned will increase substantially in the future (fig. 7.6), 

allowing a higher likelihood of ignition and flaming fronts 

to reach some low sagebrush communities. The extent to 

which these sites will carry fire depends on herbaceous production and probably on magnitude of invasion by annual 

grasses (especially cheatgrass). In summary, climate change 

may influence low sagebrush systems by reducing seedling 

establishment in unfavorable years. In addition, projected 

increased fire activity will decrease the abundance of low 

sagebrush relative to other species, especially if nonnative 

annual grasses, such as medusahead (Taeniatherum caputmedusae) and cheatgrass, become more prevalent.

Relative to other sagebrush species, low and black 

sagebrush have limited adaptive capacity. Black sagebrush 

hybridizes with silver sagebrush, and sprouting is thought 

to be a heritable trait in crosses between nonsprouting and 

sprouting sagebrushes (McArthur 1994). In the Northern 

Rockies region, however, it is unlikely that silver sagebrush 

will exhibit a significant presence in areas that support 

low sagebrush; the distribution of these species is usually 

disjunctive, so the possibility of inheriting sprouting traits 

is unlikely. In addition, the relatively low productivity 

characterizing low sagebrush sites may also limit adaptive 

capacity, especially if other risk factors are present.

Risk Assessment

Magnitude of effects: High. The resilience of many of 

these areas is low given the thin and argillic soil properties 

characterizing these sites. The magnitude of effects is likely 

to increase if other perturbations such as improper recreational or grazing schemes are present. The low adaptive 

capacity of this sagebrush type, intolerance of fires, and low 

rate of reproduction act in concert to increase the magnitude 

of effects.

Likelihood of effects: Moderate to high. Models suggest 

increased production at higher elevations (Reeves et al. 

2014), increasing the likelihood of fires carrying through 

otherwise relatively unburnable landscapes. The problem of 

increased flammability will increase, especially if invasive 

Figure 7.6—Change in big sagebrush 

habitat suitability (a–d) based on 

species distribution models using 

climate (c)-(d) or ecohydrology (a)-

(b), along with germination (e) and 

seedling survival potential (f) for NR 

(outlined in bold). Projected change 

in big sagebrush habitat suitability 

is between 1970–1999 climate and 

future A2 scenario (a)-(c) and B1 

scenario (b)-(d) 2070–2099 emission 

scenarios. Red cells indicate areas 

of decrease in big sagebrush habitat 

suitability, blue cells indicate areas 

of increase, white cells indicate 

stable areas, and gray cells indicate 

absence of big sagebrush. Maps 

of germination (e) and seedling 

survival (f) represent current 

conditions and are summarized as 

fraction of years with successes: red 

(0, no years with success), tan (>0), 

green (1, every year with success). 

Black cells indicate data not 

available (data source: Schlaepfer et 

al. 2012).

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 289

annual grasses exhibit a significant presence on short sagebrush sites in the future.

Shrublands Dominated by Sprouting 

Sagebrush Species (Threetip and 

Silver Sagebrush)

Significant areas of threetip and silver sagebrush shrublands have been converted to agricultural lands. Those 

that remain are often used for domestic livestock grazing 

because of the palatable herbaceous undergrowth in this 

sagebrush type. Those that have had chronic improper grazing typically have a large amount of bare ground, low vigor 

of native herbaceous species, and as a result, nonnative plant 

species present in varying amounts. Prolonged improper 

livestock grazing, native ungulate herbivory, and nonnative 

invasive plants are the primary stressors. Loss of topsoil 

can occur if vegetation cover and density decline and bare 

ground increases, primarily caused by ungulate impacts 

(e.g., grazing and mechanical/hoof damage) (Sheatch and 

Carlson 1998; Washington-Allen et al. 2010).

Both species can sprout from the root crown following 

top kill (primarily from fire) (Bunting et al. 1987), but this 

trait depends on site conditions and fire severity. Silver 

sagebrush is a vigorous sprouter (Rupp et al. 1997), whereas 

threetip sagebrush is less successful as a sprouter, and its 

response varies with site characteristics (Akinsoji 1988; 

Bunting et al. 1987). Both species occur on mesic sites; 

threetip sagebrush is often associated with mountain big 

sagebrush communities, and silver sagebrush typically occupies moist riparian benches or moist toe slopes. Although 

these species will sprout, increased fire frequency and severity (particularly in threetip communities) may cause a shift 

in community composition to dominance by fire-adapted 

herbaceous species or nonnative species. Other fire-adapted 

shrub species may increase, particularly following fire. In 

addition, if spring and winter precipitation increase, exotic 

annual grasses may establish and set seed earlier than the 

native perennial grasses, particularly in lower elevation 

communities (Bradley 2008; D’Antonio and Vitousek 

1992). This creates an uncharacteristic, continuous fine fuel 

load that can burn by late spring/early summer, burning 

sagebrush and native grasses often before they have matured 

and set seed (Chambers and Pellant 2008). Other nonnative 

invasive species respond favorably after fire, and, if present, 

will increase in cover and density.

Historical fire return intervals for both species are 

relatively short and research shows that threetip sagebrush 

cover can return to preburn levels 30 to 40 years after fire 

(Barrington et al. 1988; Neuenschwander n.d.). Lesica et 

al. (2007) found that after a fire in southwestern Montana, 

threetip sagebrush cover did not increase by resprouting, but 

instead established from seed. These generalizations will 

vary considerably depending on site conditions and postfire 

management. All three subspecies of silver sagebrush sprout 

after fire, and along with threetip, also typically occur on 

more mesic sites. With a warmer and drier climate, not only 

may frequent high-severity burns cause initial mortality, but 

sites may not be as favorable for postfire vegetation regeneration (from sprouting, regrowth, or seed). Invasive species 

are likely either to expand into these communities after fire 

or to increase in abundance in altered conditions that are 

less favorable to the native plant community.

Understory composition in both communities may 

possibly shift to more-xeric grassland species (e.g., bluebunch wheatgrass, needle-and-thread grass [Hesperostipa 

comata]), which are better adapted to warmer and drier conditions. Both of these sagebrush species may shift landscape 

position to sites with more moisture and cooler temperature 

(e.g., higher elevation, lower landscape position, and northeast aspects).

Risk Assessment

Magnitude of effects: Moderate

Likelihood of effects: High

Mountain Big Sagebrush Shrublands

Some areas of mountain big sagebrush shrublands have 

been converted to agricultural lands, and those that remain 

are used for domestic livestock grazing, primarily because 

of the palatable herbaceous undergrowth. Those that have 

had chronic improper grazing typically have high bare 

ground and low vigor of native herbaceous species; as a result, nonnative plant species are present in varying amounts. 

Prolonged improper livestock grazing, native ungulate 

herbivory, and invasive nonnative plants are the primary 

stressors. Loss of topsoil can occur if vegetation cover and 

density decline and bare ground increases due to improper 

grazing and other impacts, primarily caused by ungulates 

(e.g., grazing and mechanical/hoof damage). Lack of fire is 

also a chronic stressor, facilitating establishment of conifers, 

which increase in density and cover over time (Arno and 

Gruell 1986; Heyerdahl et al. 2006) while grass cover declines (Arno and Gruell 1983).

Mountain big sagebrush is killed by fire. If fire severity 

and frequency increase, there will be a shift in community composition to dominance by fire-adapted shrub 

and herbaceous species and possibly nonnative species. 

Fire-adapted shrub species may increase in abundance 

following fire (Fischer and Clayton 1983; Smith and 

Fischer 1997). In addition, if spring and winter precipitation increase, establishment of nonnative annual grasses 

(particularly cheatgrass, which germinates in winter/early 

spring) may be facilitated, although this is less likely in 

cooler, moister mountain big sagebrush communities than 

in lower elevation Wyoming and basin big sagebrush 

communities. With a warmer, drier climate, however, the 

conditions may be conducive to cheatgrass establishment. 

An abundance of cheatgrass creates an uncharacteristic, 

continuous fine fuel load that can burn by late spring/early 

summer, burning sagebrush and native perennial grasses 

often before they have matured and set seed (Chambers et 

al. 2007; Pellant 1990; Whisenant 1990), especially in the 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
290 USDA Forest Service RMRS-GTR-374. 2018

Great Basin. However, other research in the northern edge 

of the Great Basin indicates that some sagebrush communities may be less susceptible to cheatgrass invasion 

following fire, at least under the current climate (Lavin 

et al. 2013; Seefeldt et al. 2007). Other nonnative species 

respond favorably after fire and, if present, will increase in 

cover and density.

Historically, the fire return intervals were relatively 

short but variable—a few decades (Lesica et al. 2007) to 

more than 100 years (Baker 2013)—compared to Wyoming 

big sagebrush habitat (more than 100 years) (Heyerdahl 

et al. 2006; Lesica et al. 2005, 2007). Mountain big sagebrush regenerates from seeds shed from nearby unburned 

plants. It will fully recover between 15 and 40 years after 

fire (Bunting et al. 1987), depending on site characteristics 

and fire severity. In a warmer and drier climate, frequent 

high-severity burns (facilitated by cheatgrass) may not 

cause initial mortality and create unfavorable conditions 

for postfire regeneration (from sprouting, regrowth, or 

seed). There is no viable sagebrush seedbank; if fires burn 

large areas and there are no live, seed-bearing sagebrush 

nearby, there may be a type conversion to grassland. In 

addition, invasive nonnative species are likely either to expand into these areas after fire, or to increase in abundance 

due to altered conditions that no longer favor the native 

plant community (Bradley 2008; D’Antonio and Vitousek 

1992).

Mountain big sagebrush is not fire adapted, and may 

decline in cover and density or be extirpated in response to 

warmer temperatures and increased fire frequency and severity. Over time, especially if fine fuels such as senesced 

cheatgrass are present, more frequent fires may eliminate 

mountain big sagebrush from a community (Chambers and 

Pellant 2008; D’Antonio and Vitousek 1992; Whisenant 

1990). However, because mountain big sagebrush occurs 

at higher elevations, typically on more productive cooler, 

mesic sites, these communities are typically less invaded 

by nonnative species. If these sites become warmer and 

drier, however, herbaceous understory composition could 

shift to more xeric species that are better adapted, and bare 

ground may increase (Chambers et al. 2014). As a result, 

invasive species, particularly cheatgrass, could expand into 

and establish dominance in these altered communities.

The distribution of mountain big sagebrush possibly 

may shift to cooler and moister sites (e.g., higher elevation, northeast-facing snow-filled depressions). With 

climate change, it may be able to persist only in sites with 

higher moisture and deeper soils than the surrounding 

landscape. Understory composition may shift to morexeric grassland species, that are more tolerant of warmer, 

drier conditions.

Risk Assessment

Magnitude of effects: Moderate

Likelihood of effects: Moderate

Adapting Rangeland Vegetation 

Management to Climate Change 

in the Northern Rockies Region

Rangeland vegetation in the Northern Rockies Region 

is likely to be affected by changing fire regimes, increased 

drought, and increased establishment of invasive species in 

a changing climate. Effects of climate change will also compound existing stressors on rangeland ecosystems caused by 

human activities. Thus, adaptation strategies and tactics for 

rangeland vegetation focused on increasing the resilience of 

rangeland ecosystems, primarily through invasive species 

control and prevention (table 7.3).

To control invasive species in rangelands, managers 

stressed the importance of using ecologically based invasive 

plant management (EBIPM) (Krueger-Mangold et al. 2006; 

Sheley et al. 2006). The EBIPM framework focuses on strategies to repair damaged ecological processes that facilitate 

invasion (James et al. 2010). For example, prescribed fire 

treatments can be used where fire regimes have been altered, 

and seeding of desired natives can be done where seed 

availability and dispersal of natives is low.

Another adaptation strategy is to increase proactive 

management actions to prevent establishment of invasive 

species. Early detection, rapid response (EDRR) for new invasions was the most frequently suggested tactic to prevent 

invasive species establishment. Other tactics include implementing weed-free policies, conducting outreach to educate 

employees and the public about invasive species (e.g., teach 

people to clean their boots), and developing weed management areas that are collaboratively managed by multiple 

agencies, nongovernmental organizations, and the public.

In addition to invasive species control and prevention, 

grazing management will be important in maintaining 

and increasing resilience of rangelands to climate change. 

Climate changes will lead to altered availability of forage, 

requiring some reconsideration of grazing strategies. For example, reducing grazing in July and August may encourage 

growth of desired perennials in degraded systems. Livestock 

grazing can also be managed through the development of 

site-specific within-season triggers and end point indicators 

that would inform livestock movement guides and allow for 

the maintenance and enhancement of plant health.

A changing climate has led to a decline of pollinators 

in some communities (Potts et al. 2010) and may lead to 

phenological mismatches between pollinators and host 

plants (Forrest 2015). Pollinator declines may negatively 

affect the health of grasslands in the Northern Rockies, and 

encouraging native pollinators may be key to sustaining 

these ecosystems. Tools to promote native pollinators include revegetation with native species, appropriate herbicide 

and insecticide use, and education. Implementing long-term 

monitoring of pollinators can help to identify where treatments can be prioritized.

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 291 Table 7.3—Adaptation options that address climate change effects on rangelands in the Northern Rockies. Sensitivity to climatic variability and change: Increased susceptibility of vegetation communities (e.g., grasslands) to invasive species. Adaptation strategy/approach: Increase proactive management actions in order to prevent invasive species. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Conduct ecologically based invasive plant management; implement prescriptive grazing, fire, herbicide and re-seeding. Develop weed management areas and coordinate with multiple agencies, non- governmental organizations, and the public. Apply early detection rapid response (EDRR) and inventory and mapping. Where can tactics be applied? Prioritize small/new invasions by most critical species; work back to road corridors and developed areas. Recreation high use areas (roads); administrative areas All lands Specific tactic – D Specific tactic – E Specific tactic – F Tactic Use best invasive management practices to address vectors; emphasize invasive species education (e.g., teach people how to clean their equipment, boots). Remove conifers with mechanical treatments, prescribed fire, and harvest. Conduct integrated weed management (i.e., spraying, chemical, biological, mechanical, manual control, targeted grazing). Where can tactics be applied? Forest/grassland/region level Encroached communities Recreation high-use areas (roads), administrative areas

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
292 USDA Forest Service RMRS-GTR-374. 2018 Table 7.3(cont.)—Adaptation options that address climate change effects on rangelands in the Northern Rockies. Sensitivity to climatic variability and change: Increased temperature and drought will cause more and larger wildfires, leading to mortality of sagebrush and grasslands and increased dominance of fire-adapted herbaceous and non-native species. Adaptation strategy/approach: Maintain intact ecosystems, and increase resilience and resistance of native sagebrush-grass ecosystems. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Inventory intact areas with high native cover (i.e., weed-free areas). Employ preventative measures to reduce the spread and introduction of invasive species into intact/weed free plant communities. Manage priority invasive species on priority acres. Where can tactics be applied? On all land Areas that are currently weed free In priority areas Specific tactic – D Specific tactic – E Specific tactic – F Tactic Restore to minimize or reverse adverse effects. Manage fire for resource benefits. Promote the occurrence and growth of native species. Where can tactics be applied? Degraded non-forest vegetation communities Priority areas based on current condition and potential response to fire Sagebrush-dominated areas where native species have significant populations and nonnatives are not dominant Specific tactic – G Specific tactic – H Specific tactic – I Tactic Determine and implement proper grazing; conduct adaptive management that recognizes climate changes will lead to different availability of range; use rest and rotation practices; reduce grazing in July and August to encourage perennial growth. Manage livestock grazing through planning efforts that serve as livestock movement guides (within-season triggers) and allow for the maintenance and/or enhancement of plant health (end-point indicators). Use targeted grazing to address contemporary vegetation management challenges (e.g., control invasive nonnative and noxious weeds and undesirable species, and reduce fire risk). Where can tactics be applied? On all grazed lands On all grazed lands Priority areas based on current condition and potential response to treatment

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 293 Table 7.3(cont.)—Adaptation options that address climate change effects on rangelands in the Northern Rockies. Sensitivity to climatic variability and change: Phenological mismatch between pollinators and host plants. Adaptation strategy/approach: Maintain and restore natural grassland habitat to ensure pollination. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Encourage native pollinators; provide other habitats for pollinators (nesting cover, feeding cover, brooding cover). Restore and enhance habitat (using tools such as grazing, fire, herbicide application, reseeding). Implement long-term monitoring of pollinators (e.g., research, tech transfer, education, citizen science projects, and monitor existing populations). Where can tactics be applied? Throughout current range of grasslands Use ecological site descriptions to identify priority areas for restoration or enhancement. Look at native and nonnative ecosystems, overlap in these ecosystems, and the types of pollinators present. Sensitivity to climatic variability and change: Loss of topsoil and invasion of weeds in montane shrublands. Adaptation strategy/approach: Maintain and increase montane shrublands. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Educate fuels specialists, forest ecologists, wildlife biologists and silviculturists on ecology and disturbances affecting shrublands; effects of repeated burns; shifting mosaics (creating a balance of types across landscapes); and weeds (identification, awareness, reporting). Maintain adequate shrub cover, vigor, and species richness, and avoid bare ground; create different age classes and compositions of shrubfields (shifting mosaic); no action is a viable alternative dependent on system; tools include removal of timber products, targeted grazing, prescribed burning, and mastication/ slashing. Apply early detection rapid response (EDRR), and use ecologically based invasive plant management (EBIPM); tools include biocontrol, herbicides, timing burning prescriptions (to avoid annual brome expansion), and targeted grazing. Where can tactics be applied? Throughout and across jurisdictional boundaries Throughout and across jurisdictional boundaries Throughout and across jurisdictional boundaries

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
294 USDA Forest Service RMRS-GTR-374. 2018

In montane shrublands, existing stressors include fire 

exclusion and conifer establishment, browsing by both 

native and domestic ungulates, and insects and disease. 

Characteristic species can be lost in these systems with loss 

of topsoil following frequent, hot fires. Warmer temperatures and drier conditions with climate change may lead to 

an increase in high-severity fires. Adaptation tactics include 

implementing fuel reduction projects such as brush cutting, 

slashing, mastication, and targeted browsing; reestablishing 

appropriate fire regimes may prove beneficial in maintaining 

these shrublands and increasing their resilience. To control 

invasive vegetation, EDRR and EBIPM can be applied, 

along with maintenance of adequate shrub cover, vigor, 

and species richness. Educating specialists on ecology and 

disturbances affecting shrublands, effects of repeated burns, 

reforestation needs, and reporting on weeds will also help to 

maintain these systems.

More specific details on adaptation strategies and tactics 

that address climate change effects on rangeland vegetation 

in each Northern Rockies Adaptation Partnership subregion 

are in Appendix 7A.

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Appendix 7A—Adaptation Options for Nonforest 

Vegetation in the Northern Rockies.

The following tables describe climate change sensitivities and adaptation strategies and tactics for nonforest vegetation, 

developed in a series of workshops as a part of the Northern Rockies Adaptation Partnership. Tables are organized by subregion within the Northern Rockies. See Chapter 7 for summary tables and discussion of adaptation options for nonforest 

vegetation.

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
300 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.1—Adaptation options that address climate change effects on nonforest vegetation in the Central Rockies subregion. Sensitivity to climatic variability and change: Increased susceptibility of vegetation communities (e.g., grasslands) to invasive species. Effects of climate change on grasslands will be amplified by management actions. Adaptation strategy/approach: Increase proactive management actions in order to prevent invasive species Strategy objective: Reduce stressors/threats, engage coordination, increase knowledge Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Conduct integrated weed management (i.e., spraying, chemical, biological, mechanical, manual control, education, targeted grazing). Develop weed management areas and coordinate with multiple agencies, non-governmental organizations, and public. Apply early detection rapid response (EDRR) and inventory and mapping. Update weed risk assessment (WRA) to enhance integrated weed management. Tactic effectiveness (risks) High High (if properly implemented) High Moderate Implementation urgency Near term Near term Near term Mid term Where can tactics be applied? (geographic) Recreation high use areas (roads), administrative areas; Lolo Creek (Missoula District for sheep/goat grazing) Recreation high use areas (roads); administrative areas Wilderness protected areas Multi-scale effort Opportunities for implementation Coordinate with multiple agencies, non-governmental organizations, public; opportunity to graze in newly acquired lands (sheep/goats) Coordinate with multiple agencies, non-governmental organizations, public Coordinate with multiple agencies, non-governmental organizations, public, employees Coordinate with Federal and State agencies Cost Expensive Inexpensive/moderately expensive (depends on implementation scale) Inexpensive/moderately expensive Moderately expensive Barriers to implementation Management support; conflict between bighorn sheep and domestic Community support; social economic barriers (e.g., education, trust, holdouts) Lack of acceptance that it is a priority Time, lack of prioritization 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 301 Table 7A.2—Adaptation options that address climate change effects on nonforest vegetation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Increased temperature and drought will cause more and larger wildfires, leading to mortality of sagebrush and grasslands and increased dominance of fire-adapted herbaceous and non-native species. Adaptation strategy/approach: Maintain intact ecosystems, and increase resilience and resistance of native sagebrush-grass ecosystems. Strategy objective: Promote resilience, reduce stressors/threats, engage coordination, and increase knowledge. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Inventory intact/high native cover/weed free areas. Employ preventative measures to reduce the spread and introduction of invasive species into intact/weed free plant communities. Survey for new invasive species. Manage priority invasive species on priority acres. Tactic effectiveness (risks) High Moderate to high High Moderate Implementation urgency Near term Near term Near term Near term Where can tactics be applied? (geographic) On all lands (where access can be granted) Areas that are currently weed free On all lands (where access can be granted) On priority acres Opportunities for implementation Work with agencies, counties, State, non-profit and private land owners to share and incorporate current and future inventory data Work with agencies, counties, State, non-profit and private land owners to partner in weed prevention strategies and practices Work with agencies, counties, State, non-profit and private land owners to share and incorporate current and future survey data, technology Work with agencies, counties, State, non-profit and private land owners to collaborate on invasive species management activities Cost Moderately expensive Inexpensive to moderately expensive Moderately expensive Inexpensive to moderately expensive Barriers to implementation Some to major barriers: staff capacity; budgets; priorities Some to major barriers: public and internal awareness and perception; funding Some to major barriers: staff capacity; budgets; priorities Some to major barriers: budget; plant identification and phenology; capacity

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
302 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.2 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Increased temperature and drought will cause more and larger wildfires, leading to mortality of sagebrush and grasslands and increased dominance of fire-adapted herbaceous and nonnative species. Adaptation strategy/approach: Maintain intact ecosystems, and increase resilience and resistance of native sagebrush-grass ecosystems. Strategy objective: Promote resilience, reduce stressors/threats, engage coordination, and increase knowledge. Specific tactic – E Specific tactic – F Specific tactic – G Specific tactic – H Tactic Restore to minimize or reverse adverse effects. Manage conifer encroachment. Manage fire for resource benefits. Promote the occurrence and growth of early-season natives. Tactic effectiveness (risks) Moderate to high Low to high Moderate to high Moderate Implementation urgency Near term Near term Near term Short term Where can tactics be applied? (geographic) Degraded non-forest vegetation communities Priority areas based on current condition and potential response to treatment Priority areas based on current condition and potential response to fire Sagebrush-dominated areas where native species have significant populations and non-natives are not dominant Opportunities for implementation Collaborate with partners on the design and implementation of restoration activities Collaborate with partners on conifer encroachment management activities Collaborate with agencies, counties, state, non-profit and private land owners on fire management Coordinate with range permittees Cost Inexpensive to expensive Inexpensive to moderately expensive Inexpensive to moderately expensive Moderately expensive, depending on work needed Barriers to implementation Some to major barriers: awareness and recognition of need Some to major barriers: litigation; burn windows; awareness and recognition of need Some to major barriers: Recognition of need; public and internal perception and risk aversion Some barriers: Some public opposition

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 303 Table 7A.2 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Increased temperature and drought will cause more and larger wildfires, leading to mortality of sagebrush and grasslands and increased dominance of fire-adapted herbaceous and nonnative species. Adaptation strategy/approach: Maintain intact ecosystems, and increase resilience and resistance of native sagebrush-grass ecosystems. Strategy objective: Promote resilience, reduce stressors/threats, engage coordination, and increase knowledge. Specific tactic – I Specific tactic – J Specific tactic – K Specific tactic – L Tactic Reduce grazing in July and August to encourage perennial growth. Manage livestock grazing through planning efforts that serve as livestock movement guides (within- season triggers) and allow for the maintenance and/or enhancement of plant health (end-point indicators). Use targeted grazing to address contemporary vegetation management challenges (e.g., control invasive exotic and noxious weeds and undesirable species, reduce fire risk). Identify and manage (e.g., close, obliterate, re-route) non-system/user created routes (roads and trails). Tactic effectiveness (risks) Moderate Low to moderate Low to moderate Low to high Implementation urgency Mid term Near term Near to mid term Near term Where can tactics be applied? (geographic) Areas with high probability of recovery, primarily moist sites On all grazed lands Priority areas based on current condition and potential response to treatment On priority areas Opportunities for implementation Coordinate with range permittees Livestock managers Livestock managers Partner with National Forest Foundation, NGOs Cost Inexpensive Inexpensive to moderately expensive Inexpensive to moderately expensive Inexpensive to moderately expensive Barriers to implementation Opposition by some permittees Commitment by managers; compliance by livestock managers; staff capacity Public perception, National Environmental Policy Act; litigation; logistics and access Awareness; detection; budget; perception of need (internal and external); 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
304 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.3—Adaptation options that address climate change effects on nonforest vegetation in the Grassland subregion. Sensitivity to climatic variability and change: Phenological mismatch between pollinators and host plants. Adaptation strategy/approach: Maintain and restore natural habitat to ensure pollination. Strategy objective: Promote resilience, reduce stressors/threat. Specific tactic – A Specific tactic – B Tactic Restore and enhance habitat (using tools such as grazing, fire, herbicide application, reseeding). Implement long term monitoring of pollinators (e.g., research, tech transfer, education, citizen science projects, and monitor existing populations). Tactic effectiveness (risks) Depends on the combination of tools Not applicable Implementation urgency Near term Near term Where can tactics be applied? (geographic) Use ecological site descriptions to identify priority areas for restoration or enhancement Look at native and non-native ecosystems, overlap in these ecosystems and the types of pollinators present Opportunities for implementation Take advantage of other restoration activities; public involvement Search for existing information; engage with Natural Resources Conservation Service, Agricultural Research Service, state extensions, North Dakota Department of Agriculture for education on pollinators and agricultural practices; opportunity for citizen science projects to detect broad trends Cost Cost varies by tool; shared cost with other restoration projects Inexpensive with partnerships (i.e., citizen science projects) Barriers to implementation Some of the restoration tools may adversely impact the habitat.

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 305 Table 7A.4—Adaptation options that address climate change effects on nonforest vegetation in the Grassland subregion. Sensitivity to climatic variability and change: Encroachment of native species into grasslands (i.e., willow [Salix], sumac [Rhus], juniper [Juniperus], snowberries 

[Gaultheria], ponderosa pine [Pinus ponderosa]).Adaptation strategy/approach: Restore natural disturbance regimes in grasslands. Strategy objective: Promote resilience, reduce stressors/threats

Specific tactic – A Specific tactic – B Specific tactic – C

Tactic Conduct prescribed fires. Conduct mechanical treatments 

(chainsaws, mowing, mastication, logging, lop and scatter, haying, grazing).

Use herbicide (use appropriate delivery method).

Tactic effectiveness (risks) Moderate Moderate/high High 

Implementation urgency Where can tactics be applied? (geographic)

Use ecological site descriptions to determine where to apply prescribed fire 

Opportunities for implementationCostBarriers to implementation

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
306 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.5—Adaptation options that address climate change effects on nonforest vegetation in the Grassland subregion. Sensitivity to climatic variability and change: Encroachment of nonnative species into grasslands (i.e., leafy spurge [Euphorbia esula], knapweed [Centaurea], sulphur cinquefoil [Potentilla recta], Canada thistle [Cirsium arvense], Russian olive [Elaeagnus angustifolia], hounds tongue [Cynoglossum officinale], redtop [Agrostis stolonifera], cattail [Typha], reed canary grass [Phalaris arundinacea], paleyellow iris [Iris pseudacorus], Japanese brome [Bromus japonicus], Kentucky bluegrass [Poa pratensis], smooth brome [Bromus inermis], crested wheatgrass [Agropyron cristatum], cheatgrass [Bromus tectorum], sweet clover [Melilotus], absinth wormwood [Artemisia absinthium], black henbane [Hyoscyamus niger], buckthorn [Rhamnus]). Adaptation strategy/approach: Maintain and increase resilience of native grassland communities. Strategy objective: Promote resilience. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Use ecological site descriptions to prioritize areas for treatment (would not apply to all the species listed above). Apply biological control. Implement prescriptive grazing, fire, herbicide and re-seeding (timing, duration, frequency, kind and class of livestock). Tactic effectiveness (risks) Moderate/high Low-high Moderate/high Implementation urgency Near term Dependent on research Near term Where can tactics be applied? (geographic) Forest/grassland/subregion level Where it is likely to be effective and not have unintended consequences Forest/grassland/sub region level Opportunities for implementation Interagency weed working groups Interagency weed working groups Interagency weed working groups; US Fish and Wildlife Service; interagency fire program; ranchers Cost Varies Varies by agent Moderately expensive/ expensive Barriers to implementation Lack of knowledge; funding and training Uncertainty and unintended consequences of using biological control in a changing climate Social perceptions (e.g., grazing, fire, herbicide use)

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 307 Table 7A.5 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Grasslands subregion. Sensitivity to climatic variability and change: Encroachment of non-native species into grasslands. Adaptation strategy/approach: Maintain and increase resilience of native grassland communities. Strategy objective: Promote resilience. Specific tactic – D Specific tactic – E Specific tactic – F Specific tactic – G Tactic Apply early detection rapid response. Use best invasive management practices to address vectors; emphasize invasive species education (e.g., teach people how to clean their equipment, boots). Conduct internal and external education and outreach. Maintain and increase agency, State and county cooperation on invasive weeds. Tactic effectiveness (risks) High High High High Implementation urgency Near term Near term Near term Near term Where can tactics be applied? (geographic) Wherever new invasions are Forest/grassland/region level Forest/grassland/region level Forest/grassland/region level Opportunities for implementation Interagency weed working groups Interagency weed working groups; field technicians Interagency weed working groups; field technicians Interagency weed working groups Cost Inexpensive Inexpensive Inexpensive Inexpensive Barriers to implementation Plant identification skills Plant identification skills; turnover of local population Plant identification skills; turnover of local population Coordinated action (need mechanism to ensure continued coordination)

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
308 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.6—Adaptation options that address climate change effects on nonforest vegetation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Increase in fire frequency and intervals, invasive species, herbivory, and species shift (C4) Adaptation strategy/approach: Increase resilience of C3 grassland communities to the above sensitivities, and maintain C3 grassland communities on the landscape. Strategy objective: Promote resilience, reduce stressors/threats. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Allow natural and prescribed fire. Conduct ecologically based invasive plant management; use herbivory (goats), biocontrol, wildfire, and seeding (e.g., smooth brome). Conduct inventory of data, including maps and risk assessments; use Early Detection Rapid Response (EDRR) and weed-free policies regarding stock; conduct inventory and monitoring. Remove conifers with mechanical treatments, prescribed fire, and harvest. Tactic effectiveness (risks) Moderate Moderate High High Implementation urgency Mid term Near term Near term Near term Where can tactics be applied? (geographic) Expand beyond wildland urban interface; apply in areas with healthy vegetation Prioritize small/new invasions by most critical species; work back to road corridors and developed areas EDRR for all new findings Encroached communities Opportunities for implementation Implement projects per forest management plan Effective at local levels; not at landscape scale Effective at local levels; not at landscape scale Small watershed or landscape of 1000–1500 acres Cost Cost varies by project size and complexity Moderately expensive Inexpensive Moderately expensive Barriers to implementation Some barriers: Community acceptance; litigation; risk aversion; lack of non-WUI funding Major barriers: Community acceptance; capacity; need to scale up to be effective; perceived lack of urgency Some barriers: Lack of champions; workforce availability; perceived lack of urgency Some barriers: Staffing; litigation; availability of burn windows; fiscal year limitations; risk aversion

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 309 Table 7A.7—Adaptation options that address climate change effects on nonforest vegetation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Increase in fire severity and frequency, invasive species, and herbivory. Adaptation strategy/approach: Increase resilience of mountain sagebrush community to the above sensitivities, and maintain sagebrush communities on the landscape. Strategy objective: Maintain current trend. Promote resilience. Reduce stressors/threats. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Strategically place fuels treatments (thinning, mulching, limited suppression) across the landscape. Conduct ecologically based invasive plant management (EBIPM); use herbivory (goats), biocontrol, wildfire, and seeding. Conduct inventory of data, including maps and risk assessments; use Early Detection Rapid Response (EDRR) and weed-free policies regarding stock; conduct inventory and monitoring. Tactic effectiveness (risks) Moderate Moderate High Implementation urgency Near term/mid term Near term Near term Where can tactics be applied? (geographic) Expand beyond wildland urban interface; apply in areas with existing healthy vegetation Prioritize small/new invasions by most critical species; work back to road corridors and developed areas EDRR for all new findings Opportunities for implementation Implement projects per forest management plan; be opportunistic when wildfire does strike (crew availability; community acceptance) Public Lands Day and other volunteer projects; partner with wildlife and other stakeholder groups for habitat improvement Public Lands Day and other volunteer projects; partner with wildlife and other stakeholder groups for habitat improvement (Trout Unlimited, friends group). Cost Moderately expensive; cost varies by project size and complexity Moderately expensive Inexpensive Barriers to implementation Some barriers: political; community acceptance; litigation; risk aversion; lack of non-wildland urban interface funding Major barriers: community acceptance; availability of workforce; need to scale up to be effective; perceived lack of urgency Some barriers: lack of champions; workforce availability; perceived lack of urgency

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
310 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.7 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Increase in fire severity and frequency, invasive species, and herbivory. Adaptation strategy/approach: Increase resilience of mountain sagebrush community to the above sensitivities, and maintain sagebrush communities on the landscape. Strategy objective: Maintain current trend. Promote resilience. Reduce stressors/threats. Specific tactic – D Specific tactic – E Tactic Determine and implement proper grazing; conduct adaptive management that recognizes climate changes will lead to different availability of range; use rest and rotation practices. Remove conifers with mechanical treatments, prescribed fire, and harvest. Tactic effectiveness (risks) High High Implementation urgency Moderate Near term Where can tactics be applied? (geographic) Everywhere Encroached communities Opportunities for implementation Coordinate with range permittees; cultivate management support. Coordinate with fuels and habitat objectives for interagency and partnership work and funding; commercial harvest Cost Inexpensive Moderately expensive Barriers to implementation Some barriers: Lack of stakeholder support (real or perceived); lack of trust; noncompliance; perceived lack of urgency Some barriers: Staffing levels; litigation; uncertain availability of burn windows due to climate change; fiscal year limitations; challenges with interagency and/or non-Federal implementation and coordinated planning efforts; risk aversion

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 311 Table 7A.8—Adaptation options that address climate change effects on nonforest vegetation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Increase in fire severity and frequency, invasive species, and herbivory. Adaptation strategy/approach: Increase resilience of Wyoming sagebrush community to the above sensitivities. Strategy objective: Maintain sagebrush communities on the landscape; create and maintain a healthy and diverse plant community. Specific tactic – A Specific tactic – B Tactic Strategically place fuels treatments (thinning, mulch, limited suppression) across the landscape. Conduct ecologically based invasive plant management (EBIPM); use herbivory (goats), biocontrol, wildfire, and seeding. Tactic effectiveness (risks) Moderate Moderate (unless strict adherence to EBIPM, then high) Implementation urgency Near term/Mid term Near term Where can tactics be applied? (geographic) Anywhere we can; expand beyond wildland urban interface; apply tactic in areas with existing healthy intact vegetation; avoid degraded areas Prioritize small/new invasions by most critical species; work back to road corridors and developed areas in non-wilderness. Opportunities for implementation Implement projects per forest management plan; be opportunistic when wildfire does strike (crew availability; community acceptance) Public Lands Day and other volunteer projects; partner with wildlife and other stakeholder groups for habitat improvement (Trout Unlimited, friends groups) Cost Moderately expensive; cost varies by project size and complexity Moderately expensive Barriers to implementation Some barriers: Political; community acceptance; management and community tolerance; litigation; risk aversion; lack of non-wildland urban interface funding Major barriers: Community acceptance; availability of workforce; methodology; public perception; technology; need to scale up to be effective; perceived lack of urgency

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
312 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.8 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Increase in fire severity and frequency, invasive species, and herbivory. Adaptation strategy/approach: Increase resilience of Wyoming sagebrush community to the above sensitivities. Strategy objective: Maintain sagebrush communities on the landscape; create and maintain a healthy and diverse plant community. Specific tactic – C Specific tactic – D Tactic Conduct inventory of data, including maps and risk assessments; use Early Detection Rapid Response (EDRR) and weed-free policies regarding stock; conduct inventory and monitoring. Determine and implement proper grazing; conduct adaptive management that recognizes climate changes will lead to different availability of range; use rest and rotation practices. Tactic effectiveness (risks) High High Implementation urgency Near term Moderate Where can tactics be applied? (geographic) EDRR for all new findings Everywhere Opportunities for implementation Public Lands Day and other volunteer projects; partner with wildlife and other stakeholder groups for habitat improvement (Trout Unlimited, friends groups) Coordinate with range permittees; cultivate management support. Cost Inexpensive Inexpensive Barriers to implementation Some barriers: Lack of champions; workforce availability; perceived lack of urgency Some barriers: Lack of stakeholder support (real or perceived); lack of trust; noncompliance; perceived lack of urgency

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 313 Table 7A.9—Adaptation options that address climate change effects on nonforest vegetation in the Western Rockies subregion. Sensitivity to climatic variability and change: Increase in fires, warmer drier conditions, and invasive species, and decline in pollinators. With warmer wetter conditions, conifers are establishing in balds and snow belts because of changes in precipitation from snow to rain. Adaptation strategy/approach: Maintain healthy and intact grasslands. Strategy objective: Maintain and increase resilience from perturbation and resistance to invasive species; reduce weed invasion; increased knowledge of the ecology of grasslands. Specific tactic – A Specific tactic – B Tactic Maintain or restore adequate native plant cover, vigor, and species richness; ensure ecologically significant remnant populations of endemics are maintained; tools include appropriate grazing management, focused herbicide use, re-vegetation (with locally adapted and site specific species, forbs and graminoids), appropriate fire management, appropriate travel management, maintaining public land management of ecologically significant remnant plant communities (e.g., rough fescue, Palouse prairie), and conservation easements. Encourage native pollinators; provide other habitats for pollinators (nesting cover, feeding cover, brooding cover); tools include re-vegetation (with native species), appropriate herbicide and insecticide use, and education for public and within agency. Tactic effectiveness (risks) Low/moderate/high Moderate/high Implementation urgency Near term/ongoing Near term/ongoing Where can tactics be applied? (geographic) Throughout current range of grasslands; management activities are species specific Throughout Opportunities for implementation Acquiring remnant populations (partners: The Nature Conservancy (TNC), working with tribes, private landowners, land trusts); conservation easements (TNC, local land trusts) Xerces Society; native plant societies; local garden clubs; local conservation groups; Idaho Master Naturalists; youth organizations (high schools, 4H) Cost Inexpensive/moderately expensive Inexpensive/ moderately expensive Barriers to implementation Multiple land ownership and fragmentation; lack of scientific knowledge; reduced budgets for inventory and monitoring Farm Bill language; introduction of nonnative pollinators; use of insecticides; multiple ownerships

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
314 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.9 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Western Rockies subregion. Sensitivity to climatic variability and change: Increase in fires, warmer drier conditions, and invasive species, and decline in pollinators. With warmer wetter conditions, conifers are establishing in balds and snow belts because of changes in precipitation from snow to rain. Adaptation strategy/approach: Maintain healthy and intact grasslands. Strategy objective: Maintain and increase resilience from perturbation and resistance to invasive species; reduce weed invasion; increased knowledge of the ecology of grasslands. Specific tactic – C Specific tactic - D Tactic Step 1 - Identify and map soil types (locate molisols); Step 2 - Prioritize restoration based on Step 1; sites that were historically maintained have now shifted to conifer savannas; identify sites that were fire maintained versus snow maintained. Step 1 - Map risk areas for severe drought, and conduct snow melt risk analysis; Step 2 - Establish targeted areas for monitoring based on step 1 (re-visit and monitor established plots); Step 3 - Work with geneticists to isolate frost and drought hardiness, early emergence; Step 4 - Use seed sources with those traits (Step 3) to help vegetate specific sites that were identified in Step 1. Tactic effectiveness (risks) Step 1/2 moderate High Implementation urgency Near term Step 1 – near term; Step 2 – ongoing dependent on prioritization of areas Where can tactics be applied? (geographic) In identified and mapped areas In identified risk areas Opportunities for implementation Partnerships with Natural Resources Conservation Service (NRCS) Heritage Program (for monitoring); partner with NRCS, National Oceanic and Atmospheric Administration (snow melt data), Rocky Mountain Research Station; local cooperators to help with seed accessions and Forest Service nursery Cost Moderately expensive Moderately expensive Barriers to implementation Funding; time and personnel intensive; Requires finer-scale knowledge to be effective; higher priorities (mindset) Funding; time and personnel intensive; higher priorities? (mindset); sequential process 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 315 Table 7A.10—Adaptation options that address climate change effects on nonforest vegetation in the Western Rockies subregion. Sensitivity to climatic variability and change: Loss of topsoil and invasion of weeds. Adaptation strategy/approach: Maintain and increase montane shrublands. Strategy objective: Maintain and increase resilience from perturbation and resistance to invasive species; reduce weed invasion; increased knowledge of the ecology of shrublands. Specific tactic – A Specific tactic – B Tactic Implement fuel reduction projects (i.e., reduce conifer encroachment, brush cutting, slashing/ mastication without burning, targeted browsing); if burning is used, design prescriptions according to requirements of desired shrub species (soil moisture requirements, desired end result conditions). Maintain adequate shrub cover, vigor, and species richness, and avoid bare ground; create different age classes and compositions of shrubfields (shifting mosaic); no action is a viable alternative dependent on system; tools include removal of timber products, targeted grazing, prescribed burning, and mastication/slashing. Tactic effectiveness (risks) Moderate (unintended consequences, higher priorities) Moderate/high Implementation urgency Near term/ongoing Near term/ongoing Where can tactics be applied? (geographic) Throughout; critical areas for restoration Throughout and across jurisdictional boundaries Opportunities for implementation Partners – Rocky Mountain Elk Foundation, sportsmen associations, Idaho Fish and Game, Bureau of Land Management, Idaho Forest Landowner association; forest harvests open up new shrublands Partners – Rocky Mountain Elk Foundation, sportsmen associations, Idaho Fish and Game, BLM, Idaho Forest Landowner association, Turkey Federation Cost Inexpensive/moderately expensive (depends on scale) Inexpensive/moderately expensive (depends on scale) Barriers to implementation Current forest management policies about allowing shrubfields to be maintained rather than reforestation; mindset of current land managers (tradition) Mindset of current land managers (tradition); lack of equipment; availability of target livestock; road access; inaccessibility (slope); multi- resource objectives

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
316 USDA Forest Service RMRS-GTR-374. 2018 Table 7A.10 (cont.)—Adaptation options that address climate change effects on nonforest vegetation in the Western Rockies subregion. Sensitivity to climatic variability and change: Loss of topsoil and invasion of weeds. Adaptation strategy/approach: Maintain and increase montane shrublands. Strategy objective: Maintain and increase resilience from perturbation and resistance to invasive species; reduce weed invasion; increased knowledge of the ecology of shrublands. Specific Tactic – C Specific tactic - D Tactic Apply early detection rapid response (EDRR), and use ecologically based invasive plant management (EBIPM); tools include biocontrol, herbicides, timing burning prescriptions (to avoid annual brome expansion, and targeted grazing. Educate fuels specialists, forest ecologists, wildlife biologists and silviculturists on ecology and disturbances affecting shrublands; effects of repeated burns; shifting mosaics (creating a balance of types across landscapes); and weeds (identification, awareness, reporting). Tactic effectiveness (risks) Low/moderate Moderate Implementation urgency Near term/ongoing Near term/ongoing Where can tactics be applied? (geographic) Throughout and across jurisdictional boundaries Throughout and across land management jurisdictions Opportunities for implementation Coordinate with private landowners; cooperative weed management areas; partner with Bonneville Power, tribes, private groups such as backcountry horsemen, National Forest Foundation; use volunteer cooperators (for surveys and monitoring) Revise Forest Service manual; brownbag lunch – weed webinar; educational products such as flyers, posters; ross training and/or internal training for line officers Cost Inexpensive/moderately expensive (depends on scale) Moderately expensive Barriers to implementation Multiple jurisdictions; National Environmental Policy Act – not being able to adapt to new chemicals; logistically inaccessible (backpack or on horse); public mindset of using chemicals; budgets are prohibitive. Tie implementation to performance for achieving objectives (misuse of herbicides, treating non-target native plants); need line officer support; mindset of current land managers (tradition); public mindset of using chemicals 

Chapter 7: Effects of Climate Change on Rangeland Vegetation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 317

Introduction

This chapter describes the ecology of important disturbance regimes in the Forest Service, U.S. Department 

of Agriculture (USFS) Northern Region and the Greater 

Yellowstone Area, hereafter called the Northern Rockies region, and potential shifts in these regimes as a consequence 

of observed and projected climate change. The term disturbance regime describes the general temporal and spatial 

characteristics of a disturbance agent—insect, disease, fire, 

weather, even human activity—and the effects of that agent 

on the landscape (table 8.1). More specifically, a disturbance 

regime is the cumulative effect of multiple disturbance 

events over space and time (Keane 2013). Disturbances disrupt an ecosystem, community, or population structure and 

change elements of the biological environment, physical environment, or both (White and Pickett 1985). The resulting 

shifting mosaic of diverse ecological patterns and structures 

in turn affects future patterns of disturbance, in a reciprocal, 

linked relationship that shapes the fundamental character 

of landscapes and ecosystems. Disturbance creates and 

maintains biological diversity in the form of shifting, heterogeneous mosaics of diverse communities and habitats across 

a landscape (McKinney and Drake 1998), and biodiversity 

is generally highest when disturbance is neither too rare nor 

too frequent on the landscape (Grime 1973).

A changing climate may already be altering characteristics of disturbance agents, events, and regimes, with 

additional effects expected in the future (Dale et al. 2001). 

Climate changes can alter the timing, magnitude, frequency, 

and duration of disturbance events, as well as the interactions of disturbances on a landscape. Interactions among 

disturbance regimes, such as the co-occurrence in space 

and time of bark beetle (Dendroctonus spp.) outbreaks 

and wildfires, can result in highly visible, rapidly occurring, and persistent changes in landscape composition and 

structure. Understanding how altered disturbance patterns 

and multiple disturbance interactions might result in novel 

and emergent landscape behaviors is critical for addressing 

climate change impacts and for designing land management 

strategies that are appropriate for future climates (Keane et 

al. 2015).

We summarize five disturbance types present in the 

Northern Rockies region that are sensitive to a changing 

climate. Wildfires, bark beetles, white pine blister rust 

(Cronartium ribicola), other forest diseases, and nonnative 

plant invasions acting individually or synergistically can 

transform landscape patterns and ecological functions. 

This chapter provides background that can help managers 

understand the important role of disturbances on Northern 

Rockies landscapes, and anticipate how, when, where, and 

why climate changes may alter the characteristics of disturbance regimes.

Wildfire

Overview

Wildland fire is ubiquitous throughout forest ecosystems 

of the Northern Rockies and was historically the most 

important and extensive landscape disturbance in the region 

(Hejl et al. 1995). Wildfire emerged as a dominant process 

in North America after the end of the last glacial period, 

about 16,500 to 13,000 years B.P., commensurate with 

rapid climate changes and increased tree cover (Marlon 

et al. 2009). In the Northern Rockies region, many forest 

types are fire-prone and fire adapted, meaning that fire is an 

integral and predictable part of their maintenance and ecological functioning. Wildfire, as well as other disturbances 

such as insect outbreaks, disease, drought, invasive species, 

and storms, is part of the ecological history of most forest 

ecosystems, influencing vegetation age and structure, plant 

species composition, productivity, carbon (C) storage, water 

yield, nutrient retention, and wildlife habitat (Agee 1993).

Climate and fuels are the two most important factors 

controlling patterns of fire in forest ecosystems. Climate 

controls the frequency of weather conditions that promote 

fire, whereas the amount and arrangement of fuels influence fire intensity and spread. Climate influences fuels on 

Chapter 8: Effects of Climate Change on 

Ecological Disturbance in the Northern 

Rockies Region

Rachel A. Loehman, Barbara J. Bentz, Gregg A. DeNitto, Robert E. Keane, 

Mary E. Manning, Jacob P. Duncan, Joel M. Egan, Marcus B. Jackson, Sandra 

Kegley, I. Blakey Lockman, Dean E. Pearson, James A. Powell, Steve Shelly, 

Brytten E. Steed, and Paul J. Zambino
318 USDA Forest Service RMRS-GTR-374. 2018

longer time scales by shaping species composition and 

productivity (Dale et al. 2001; Marlon et al. 2008; Power 

et al. 2008), and large-scale climatic patterns such as the 

El Niño Southern Oscillation (ENSO) and Pacific Decadal 

Oscillation (PDO) are important drivers of forest productivity and susceptibility to disturbance (Collins et al. 2006; 

Kitzberger et al. 2007). Current and past land use, including 

timber harvest, forest clearing, fire suppression, and fire 

exclusion through grazing have affected the amount and 

structure of fuels in the United States (Allen et al. 2002; 

Falk et al. 2011; Pausas and Keeley 2014).

Disturbance effects can overwhelm the direct effects of 

climate changes on ecosystems. As described in other chapters in this publication, climate changes influence forests 

directly; for example, it has been suggested that drought 

and heat stress are linked to increased tree mortality, shifts 

in species distributions, and decreased productivity (Allen 

et al. 2010; Van Mantgem et al. 2009; Williams et al. 2013). 

However, the most visible and significant short-term effects 

of climate changes on forest ecosystems will be caused by 

altered disturbances, often occurring with increased frequency and severity. The warmer, drier conditions expected 

with climate change are likely to increase fire frequency, fire 

season length, and cumulative area burned in the coming 

decades in the western United States (Flannigan et al. 2006; 

McKenzie et al. 2004). Climate changes may also increase 

the frequency or magnitude of extreme weather events that 

affect fire behavior (Kurz et al. 2008b; Lubchenco and Karl 

2012). Although shifts in vegetation composition and distribution caused by climate alone may occur over decades 

or centuries, wildfires can temporarily or persistently reorganize landscapes over a period of days (Overpeck et al. 1990; 

Seidl et al. 2011).

The role of fire in ecosystems and its interactions with 

dominant vegetation is termed a “fire regime” (Agee 1993). 

Fire regimes are defined by fire frequency (mean number 

of fires per time period), extent, intensity (measure of the 

heat energy released), severity (net ecological effect), and 

seasonal timing (table 8.2). These characteristics vary across 

vegetation types and depend on the amount and configuration of live and dead fuel present at a site, environmental 

conditions that favor combustion, and ignition sources 

(Agee 1993; Krawchuk et al. 2009). Ecosystems in the 

Northern Rockies have been subject to a range of historical 

fire regimes, including (1) frequent (1–35 years), low- or 

mixed-severity fires that replaced less than 25 percent of 

the dominant overstory vegetation; (2) moderate-frequency 

(35–200 years), mixed-severity fires that replaced up to 75 

percent of the overstory; and (3) infrequent (200+ years), 

high-severity fires that replaced greater than 75 percent of 

Table 8.1—Characteristics used to describe disturbance regimes.a

Disturbance

characteristic Description Example

Agent Factor causing the disturbance Mountain pine beetle is the agent that kills trees

Source, cause Origin of the agent Lightning is a source for wildland fire

Frequency How often the disturbance occurs or its 

return time

Years since last fire or beetle outbreak (scale dependent)

Intensity A description of the magnitude of the 

disturbance agent

Mountain pine beetle population levels; wildland fire heat 

output

Severity The level of impact of the disturbance on the 

environment

Percent mountain pine beetle tree mortality; fuel consumption 

in wildland fires

Size Spatial extent of the disturbance Mountain pine beetles can kill trees in small patches or across 

entire landscapes

Pattern Patch size distribution of disturbance effects; 

spatial heterogeneity of disturbance effects

Fire can burn large regions but weather and fuels can 

influence fire intensity and therefore the patchwork of tree 

mortality

Seasonality Time of year at which a disturbance occurs Species phenology can influence wildland fire effects; spring 

burns can be more damaging to growing plants than fall burns 

on dormant plants

Duration Length of time that disturbances occur Mountain pine beetle outbreaks usually last for 3–8 years; 

fires can burn for a day or for an entire summer

Interactions Disturbances interact with each other, 

climate, vegetation, and other landscape 

characteristics

Mountain pine beetles can create fuel complexes that 

facilitate or exclude wildland fire

Variability Spatial and temporal variability of the above 

factors

Highly variable weather and mountain pine beetle mortality 

can cause highly variable burn conditions resulting in patchy 

burns of small to large sizes

a From Keane (2013).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 319

the dominant overstory vegetation (fig. 8.1). More-detailed 

information on fire regimes specific to individual vegetation 

species and vegetation types can be found in Chapter 6 of 

this volume.

Wildland fire behavior is influenced by variability in 

environmental conditions including vegetation type and distribution, climate, weather, and topography. Despite major 

human influences on western U.S. wildfires since EuroAmerican settlement, climate is generally considered to be 

the primary control on fire regimes in the region, influencing 

vegetation production and condition as well as the physical 

environment (Marlon et al. 2012). Where rates of vegetation 

production outpace decomposition, sufficient biomass is 

available to support fires, although higher elevation regions 

with abundant fuels do not always have sufficiently dry 

conditions to sustain a fire. In these systems, short-duration 

drying episodes generally do not create dry enough conditions to sustain a fire, but prolonged dry weather conditions 

(about 40 days without precipitation) can sufficiently dry 

live fuels and larger dead fuels to carry large, intense fires 

once they are ignited (Schoennagel et al. 2004). Wildland 

fuels lose moisture and become flammable in warm and dry 

summers typical in the Northern Rockies region, during 

which time there are ample sources of ignition from lightning strikes and humans. Therefore, the active fire season 

(period conducive to active burning) is in the summer, typically from late June through October, with shorter seasons at 

higher elevation sites, where snowpack can persist into July 

(Littell et al. 2009).

At annual time scales, weather is the best predictor of fire 

characteristics such as area burned and fire size. Correlations 

between weather and annual area burned by fire or the 

number of large fires are similar for both pre-20th-century 

fires and fires that have occurred during the past few decades. Fire-weather relationships have been constructed for 

forested ecosystems of the Pacific Northwest (Hessl et al. 

2004; Heyerdahl et al. 2002, 2008a) and Northern Rockies 

(Heyerdahl et al. 2008b; Littell et al. 2009; Westerling et al. 

2003, 2006), based on tree-ring and fire-scar records and 

independently reconstructed climate, or observations of fire 

Table 8.2— Risk assessment for fire regime changes.a

Fire regime 

component

Predicted 

direction of 

change Main driver(s) of change Projected duration of change

Likelihood of 

change

Ignitions Unknown Changes in lightning frequency and 

anthropogenic ignitions

Unknown Unknown 

Area burned Increase Increased fire season length, 

decreased fuel moistures, increased 

extreme fire conditions

Until a sufficient proportion of 

the landscape has been exposed 

to fire, thus decreasing fuel 

loads and increasing structural 

and species heterogeneity

High

Fire frequency Increase Increased ignitions, increased fuel 

loads, decreased fuel moistures, 

increased fire season length

In forested systems until a 

sufficient proportion of the 

landscape has been exposed 

to fire, reducing fuel loads 

and continuity; in grass- and 

shrubland systems, until global 

climate stabilizes

Moderate

Average fire size Increase Increased fire season length, 

decreased fuel moistures, increased 

extreme fire conditions

Until a sufficient proportion of 

the landscape has been exposed 

to fire, thus increasing the 

likelihood that previous fires 

will restrict growth of current 

year fires

High

Fire season 

length

Increase Increased temperatures, decreased 

precipitation, decreased winter 

snowpack, decreased runoff

Until the global climate system 

stabilizes; predicted to increase 

as climate changes become 

more severe

High

Fire severity Increase Decreased fuel moistures, increased 

extreme fire conditions

In dry forest types, until fires 

decrease surface fuel loads; in 

mesic forests, if increased fire 

frequency decreases fuel loads

Moderate

a Developed using expert opinion and information from literature as summarized in this chapter.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
320 USDA Forest Service RMRS-GTR-374. 2018

events and weather in the seasons leading up to and during 

the fire where records are available. Regionally, widespread 

fire years are correlated with drought (Heyerdahl et al. 

2008b; Morgan et al. 2008), and these regionally synchronous fires have generally occurred in the Northern Rockies 

(Idaho and western Montana) during years with relatively 

warm spring-summers and warm-dry summers (Heyerdahl 

et al. 2008a; Morgan et al. 2008).

In nonforested systems in the eastern Northern Rockies, 

precipitation amount, at both short (weeks to months) 

(Littell et al. 2009) and long (decades to centuries) (Brown 

et al. 2005) time scales is the dominant control on fire. 

During the fire season, the amount and timing of precipitation largely determine availability and combustibility of 

fine fuels, and short periods of dry weather are sufficient 

to precondition these systems to burn (Gedalof et al. 2005; 

Westerling and Swetnam 2003). In contrast to the grasslands 

of the southwestern United States, antecedent precipitation 

has not been found to be a significant driver of large fires in 

the northern grasslands; rather, large fires are most strongly 

correlated with low precipitation, high temperatures, and 

summer drought (July through September) in the year of the 

fire (Littell et al. 2009).

Humans are also important drivers of wildfire, via altered 

ignition patterns associated with land clearing and land 

cover change, agriculture, introduction of exotic species, 

and fire management (fuels treatments and fire suppression/exclusion). Grazing and the introduction of nonnative 

species have altered ecological processes that affect fire, 

including fuel loading and continuity, forest composition 

and structure, nutrient cycling, soils, and hydrology (Marlon 

et al. 2009; Swetnam et al. 1999). For many sagebrush 

ecosystems of low to moderate productivity, fire intervals 

are 10 to 20 times shorter today than what is estimated 

for pre-20th-century conditions (Peters and Bunting 1994; 

Whisenant 1990; see also Chapter 7), because of the spread 

and dominance of the nonnative annual cheatgrass (Bromus 

tectorum). Dry forests, shrublands, and grasslands in the 

region exist in a state of “fire deficit” as the result of fire 

exclusion, leading to less frequent wildfire, higher stand 

densities, higher fuel quantities, and higher fuel continuity. 

This has increased the potential for crown fires in forests 

with a history of low-severity fire regimes (Agee 1998; 

Peterson et al. 2005) and in some forests with mixedseverity regimes (Taylor and Skinner 2003).

Wildfire Shapes Landscape Patterns

The composition and structure of forests in the Northern 

Rockies is determined by climate, elevation, topographic 

position, and history of fire. In general, fire regimes vary 

along environmental gradients, with fire frequency decreasing and fire severity increasing with elevation (although 

aspect and slope position can influence fire patterns). For example, low-severity fires are typical in many ponderosa pine 

(Pinus ponderosa) forests at low elevations. Historically, 

fires here burned frequently enough to maintain low fuel 

loads and an open stand structure, producing a landscape in 

which fire-caused mortality of mature trees was rare (Agee 

1998; Jenkins et al. 2011; Moritz et al. 2011). Adaptive traits 

such as thick bark also allowed mature ponderosa pines to 

survive many repeated fires over time. Conversely, highseverity fires occurring at intervals of more than 300 years 

are typical in subalpine forests and tend to result in high 

mortality of mature trees (“stand replacement”) because 

Figure 8.1—Fire regime groups 

for the Northern Rockies, 

LANDFIRE mapping program. 

The fire regime group layer 

characterizes the presumed 

historical fire regimes 

within landscapes based on 

interactions among vegetation 

dynamics, fire spread, fire 

effects, and spatial context 

(see http://www.landfire.gov/

NationalProductDescriptions12.

php).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 321

long intervals between fires result in dense, multi-storied 

forest structures that are susceptible to crown fires (Agee 

1998) (fig. 8.2).

Fire exclusion since the 1920s has increased surface 

fuel loads, tree densities, and ladder fuels, especially in 

low-elevation dry conifer forests (Schoennagel et al. 2004) 

(fig. 8.3). As a result, fires in these forests may be larger and 

more intense, and may cause higher rates of tree mortality 

than historical fires. In higher elevation forests where fires 

were historically infrequent, fire exclusion has not altered 

fire regimes (Romme and Despain 1989; Schoennagel et al. 

2004). For example, large, stand-replacing fires occasionally 

occurred in lodgepole pine (Pinus contorta var. latifolia) 

forests in Yellowstone National Park (Romme 1982), and 

many (but not all) lodgepole pine trees can regenerate prolifically when heating from fires releases seed from serotinous 

cones (Schoennagel et al. 2003).

Figure 8.2—Mean fire return 

interval for the Northern 

Rockies, LANDFIRE mapping 

program. The mean fire return 

interval layer quantifies the 

average period between 

fires under the presumed 

historical fire regime (see 

http://www.landfire.gov/

NationalProductDescriptions13.

php for more information).

Figure 8.3—Vegetation condition 

class for the Northern Rockies, 

LANDFIRE mapping program. 

The vegetation condition class 

layer quantifies the amount that 

current vegetation has departed 

from the simulated historical 

vegetation reference conditions 

(see http://www.landfire.gov/

NationalProductDescriptions10.

php).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
322 USDA Forest Service RMRS-GTR-374. 2018

Wildfires and Forest Carbon Sequestration

Concerns about projected changes in global climate have 

raised an expectation that forests can help mitigate climate 

changes via management for increased carbon sequestration 

and storage (Sommers et al. 2014). Forests contain large 

reservoirs of carbon in soils (~45 percent of total storage), 

aboveground and belowground live biomass (~42 percent), 

dead wood (~8 percent), and litter (~5 percent) (Pan et al. 

2011). The carbon sequestration potential of Earth’s forests 

is about 33 percent of global emissions from fossil fuels 

and land use (Denman 2007), and North American forests 

currently offset about 13 percent of annual continental fossil 

fuel emissions (Pacala et al. 2007). The potential for forests 

to mitigate climate change depends on human activities 

such as land use and land management, and environmental 

factors such as vegetation composition, structure, and distribution, disturbance processes, and climate (Loehman et al. 

2014).

Carbon typically accumulates in woody biomass and 

soils for decades to centuries until a disturbance event such 

as wildfire releases this stored carbon into the atmosphere 

(Goward et al. 2008). Wildfire in forested ecosystems is one 

of the primary disturbances that regulate patterns of carbon 

storage and release (Kasischke et al. 2000). The amount and 

rate of carbon release from a wildfire depend on the extent 

and severity of the fire, as well as pre-disturbance site conditions and productivity (Bigler et al. 2005; Dale et al. 2001; 

Falk et al. 2007). For example, high-severity fires typical 

of mid-to-upper elevation forests in the Northern Rockies 

region may consume a large amount of aboveground biomass, resulting in an instantaneous pulse of carbon (i.e., the 

area affected becomes a carbon source to the atmosphere); 

however, these fires typically occur infrequently, and carbon 

is stored in woody biomass as forests regrow. Low-severity 

fires such as those that occur in low-elevation dry forest 

types typically release less carbon per fire event (although 

total emissions are dependent on area burned) at more frequent intervals than with stand-replacing regimes, and favor 

long-lived and fire-resistant (or tolerant) forest species that 

typically survive multiple fire events (Ritchie et al. 2007). 

Carbon losses from wildland fire are balanced by carbon 

capture from forest regrowth across unmanaged fire regimes 

and over multiple decades, unless a lasting shift in dominant 

plant lifeform occurs or fire return intervals change (Kashian 

et al. 2006; Wiedinmyer and Neff 2007).

There are several important ideas to consider when managing forests and fires for carbon resources. First, as stated 

above, unless structural or functional ecosystem shifts occur, 

net carbon balance in disturbance-adapted systems at steady 

state is zero when assessed over long time periods and at 

large spatial scales. Under these conditions, although a fire 

may result in a temporary loss of stored carbon from a forest 

to the atmosphere (i.e., the forest temporarily becomes a 

carbon source), this effect is transitory and balanced by carbon accumulation as the forest regrows. The time required 

for the postfire environment to shift from carbon source to 

sink varies among forest types and climates. For example, 

in simulations of effects of stand-scale fuels treatments on 

carbon-fire relationships in Northern Rockies forests, postfire carbon recovery occurred in 10 to 50 years, depending 

on vegetation type and whether stands were treated before 

fire to reduce woody fuels (Reinhardt and Holsinger 2010).

Second, quantifying or projecting wildland fire emissions 

is difficult because their amount and character vary greatly 

from fire to fire, depending on biomass carbon densities, 

quantity and condition of consumed fuels, combustion 

efficiency, and weather (Loehman et al. 2014). Emissions 

measured for an individual fire event may not be characteristic of large-scale emissions potential, because of complex 

ecological patterning and spatial heterogeneity of burn 

severity within fire perimeters. Although long intervals 

between wildfires can allow carbon to accumulate for years 

to centuries, disturbance-prone forests will eventually lose 

stored carbon to the atmosphere, regardless of management 

strategies designed to limit or prevent disturbance events.

Third, wildfire confers many important ecological benefits not measurable in carbon units (e.g., nutrient release 

and redistribution, stimulation of plant growth, increased 

productivity in soil systems from decomposition of burned 

material, initiation of vegetation succession and forest 

regeneration, increased availability of resources for surviving trees). Thus, it will be important to develop accounting 

methods that can assess ecological benefits in carbonequivalent units so that they can be weighed against carbon 

losses from disturbance.

Finally, climate changes in combination with other 

ecosystem stressors may be sufficient to cause structural 

or functional changes in ecosystems and thus alter carbon 

dynamics of landscapes. For example, if climate changes 

increase wildfire frequency, extent, or severity in forested 

ecosystems, forests will likely lose carbon to the atmosphere 

that will not be rapidly replaced by new growth. This will 

cause forests to act as carbon sources for a period of time 

until disturbance regimes and biomass stabilize. Future 

landscapes could have the potential to store less, or more, 

carbon than under current climate and disturbance regimes.

Potential Future Wildfire Regimes and 

Wildfire Occurrence

Potential climate-driven changes to regional fire regimes 

in the mid-to-late 21st century include longer fire seasons 

and increases in fire frequency, annual area burned, number 

of high fire danger days, and fire severity as compared with 

modern fire patterns (Bachelet et al. 2003; Brown et al. 

2004; Dillon et al. 2011; Krawchuk et al. 2009; Rocca et 

al. 2014; Westerling et al. 2006) (figs. 8.4, 8.5). In particular, lengthening of the fire season (the period of the year 

when fires can burn) will allow for more ignitions, greater 

likelihood of fire spread, and a longer burning duration. A 

longer burning window combined with regionally dry fuels 

will promote larger fires and increased annual area burned 

relative to modern recorded fire activity. Earlier onset of 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 323

Figure 8.4—Changes in mean 

annual area burned (acres) for 

current levels of fire suppression 

and no fire suppression, A1B 

(moderate) and A2 (high) 

emission scenarios, and for the 

time periods 2030–2050 and 

2080–2100, as projected by the 

MC2 dynamic global vegetation 

model.

snowmelt will reduce fuel moisture during fire season, making a larger portion of the landscape flammable for longer 

periods of time (McKenzie et al. 2004; Miller et al. 2011). 

This shift may be especially pronounced in mid- to highelevation forested systems where fuels are abundant.

Earlier snowmelt, higher summer temperatures, longer 

fire season, and expanded vulnerable area of high elevation 

forests have produced observed increased wildfire activity compared to the mid-20th century, particularly in the 

Northern Rockies region (Westerling et al. 2006). Annual 

area burned by Western wildfires in the 20th century was 

greater in years with low precipitation, high drought severity, and high temperatures (Littell et al. 2009). Wildfire 

activity in the western United States is expected to increase 

if climates become warmer and drier in the future. Among 

western U.S. forests, mid-elevation forests of the Northern 

Rockies are projected to have a high risk of climate-induced 

increase in fire (Westerling et al. 2006), and increases in the 

area burned by fire are likely in lower and middle elevations 

of mountainous areas (Littell et al. 2009). However, in areas 

that are fuel limited, fires may become more infrequent 

where there is insufficient moisture for fine fuel accumulation (Littell et al. 2009).

The potential effects of climate change on wildfire area 

have been assessed by using statistical and ecological process models for the western United States (McKenzie et al. 

2004; Spracklen et al. 2009), Pacific Northwest (Littell et al. 

2010), Northern Rockies (Holsinger et al. 2014; Loehman et 

al. 2011a,b; Rocca et al. 2014), and the Greater Yellowstone 

Area (Westerling et al. 2011). For a mean temperature 

increase of 4 oF, the annual area burned by wildfires is 

expected to increase by a factor of 1.4 to 5 for most western 

States (McKenzie et al. 2004), ultimately leading to greater 

damage, growth reductions, and mortality in forest ecosystems. The effects of future climate on fire severity (i.e., the 

proportion of overstory mortality) are less certain because 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
324 USDA Forest Service RMRS-GTR-374. 2018

severity may be more sensitive than area burned to arrangement and availability of fuels. The risk posed by future fire 

activity in a changing climate can be assessed by its likely 

effects on human and ecological systems. At the wildlandurban interface, higher population and forest density have 

created forest conditions that are likely to experience more 

area burned and possibly higher fire severity than in the 

historical record (Dillon et al. 2011) (figs. 8.4, 8.5).

Although fire size in historical sagebrush landscapes 

is poorly understood, it is generally accepted that recent 

large fires have been fueled by woodland encroachment and 

higher fine fuel loads from weed invasions (e.g., cheatgrass). 

These changes in fire regime and vegetation-fuel structure 

affect large areas in the semiarid western United States and 

cascade through all trophic levels. Effects are particularly 

harmful on landscapes where postfire recovery is slow. 

The trend for larger, more damaging fires in sagebrush 

ecosystems is expected to continue until aberrations in fuel 

conditions that drive fire are corrected (Keane et al. 2008).

Interactions with Other 

Disturbance Processes

Wildland fires and insect outbreaks are the two primary 

natural disturbance processes in conifer forests of western 

North America (Hicke et al. 2012; Jenkins et al. 2012). The 

interaction of wildland fire and bark beetles has been studied 

since the early 20th century (Evenden and Gibson 1940; 

Miller and Patterson 1927; Weaver 1943), with research 

primarily focused on the potential for increased fire hazard 

following outbreaks. Multiple studies have cited changes 

in fire behavior, extent, and severity resulting from bark 

beetle-caused mortality in pine forests (see Hicke et al. 2012 

for a summary). Drought and increased temperatures are 

key drivers of both wildland fires and bark beetle outbreaks. 

Climate change may be a causal factor in recent increases 

in annual area burned by wildfires (Littell et al. 2009) and 

area affected by bark beetle outbreaks (Bentz et al. 2010). 

Projections of warmer temperatures and increased drought 

stress suggest that the total area susceptible to or affected by 

beetle outbreaks and large or severe fires may increase in the 

coming decades (Williams et al. 2013). Acting independently 

or synchronously in space and time, wildland fires and bark 

beetle outbreaks can substantially influence forest structure, 

composition, and function; abruptly reorganize landscapes; 

and alter biogeochemical processes such as carbon cycling, 

water supply, and nutrient cycles (Edburg et al. 2012; Falk 

2013; Fettig et al. 2013; Hansen 2014; Kurz et al. 2008a).

Unknowns and Uncertainties

Projections of future climate are somewhat uncertain 

because the ultimate magnitude of climate change and the 

severity of its impacts depend strongly on the actions that 

human societies take to respond to these risks (National 

Research Council 2010). Global climate models and their 

downscaled products may not accurately represent climate 

and weather at the regional and local scales that influence 

fire occurrence and behavior. For example, although associations between fire and quasi-periodic patterns such as 

ENSO and PDO have been identified, there is incomplete 

understanding of how these will respond to climate warming 

(McKenzie et al. 2004). In addition, precipitation trends are 

highly variable, and projections of future precipitation reflect 

both uncertainty and high variation (Intergovernmental 

Panel on Climate Change [IPCC] 2007, 2012; Littell et al. 

2011). Lightning, an important ignition source for wildland fires, may increase in the future, thus increasing the 

potential for fire activity. For example, recent projections 

suggest that lightning strikes in the continental United States 

Figure 8.5—Severe fire potential 

(probability) for 90th percentile 

fire weather scenario, with 

non-burnable areas added in 

from the LANDFIRE 2008 Fire 

Behavior Fuel Model layer (data 

source: Dillon et al. 2011). 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 325

may increase by about 50 percent over the 20th century as 

the result of global warming-induced increase in updraft 

speeds and atmospheric water content (Romps et al. 2014). 

However, others have concluded that confidence in projections of increased thunderstorms and severe local weather 

events is low (Seneviratne et al. 2012).

Thus, the influence of climate changes on future fire patterns is not precisely known. Long-term changes in climate 

are unlikely to produce simple linear responses in global fire 

regimes (e.g., warmer temperatures do not always lead to 

increased fire frequency) because fire activity is influenced 

by precipitation, which is not projected accurately by climate 

models (Grissino-Mayer and Swetnam (2000). Other research suggests that increases in burned area can be expected 

in a warming climate, but fire activity will ultimately be limited by the availability of fuels (Brown et al. 2004; Flannigan 

et al. 2006; Loehman et al. 2011a; McKenzie et al. 2004; 

Torn and Fried 1992). In addition, climate drivers interact 

with legacies of human land use and local vegetation and 

fuel conditions at large spatial scales, making linear climatefire predictions difficult. Specifically, decades-long fire 

exclusion and timber harvesting in some forests of the western United States have resulted in densely stocked stands and 

heavy down woody fuels accumulation that have probably 

contributed to the anomalous size and intensity of recent fires 

(Grissino-Mayer and Swetnam 2000; Naficy et al. 2010).

Bark Beetles

Overview

Bark beetles (Coleoptera: Curculionidae, Scolytinae) make 

up a large subfamily of insects, although less than 1 percent 

of the more than 6,000 species found worldwide cause significant economic impacts. In the Northern Rockies region, 

bark beetles of economic concern feed in the phloem of living 

conifers and can have extreme population amplifications over 

short time periods, the hallmark of outbreak species. Larval 

feeding, in addition to colonization by beetle-introduced 

fungi, typically results in death of the tree, and new host 

material is therefore required for each beetle generation. 

Historically, pulses of bark beetle-caused tree mortality have 

been extensive across the northern portion of the Rocky 

Mountain region. Between 1999 and 2013, bark beetle-caused 

tree mortality had substantial impacts in the Northern Rockies 

across an average of 1.4 million acres each year (fig. 8.6). 

Mountain pine beetle (Dendroctonus ponderosae, hereafter 

referred to as MPB) caused the majority of tree mortality (82 

percent of acres with mortality detected) with a cumulative 

impact across 8.7 million acres during this time period (fig. 

8.7). Across western North America between 1997 and 2010, 

bark beetle-caused tree mortality resulted in a transfer of 

carbon that exceeded that of fire-caused tree mortality (Hicke 

et al. 2013).

Both bark beetle populations and their host trees are being 

influenced by a warmer climate. Many bark beetle life history 

traits that affect population success are temperature-dependent (Bentz and Jӧnsson 2015), and warming temperatures 

associated with climate change have directly influenced bark 

beetle-caused tree mortality in some areas of western North 

America (Safranyik et al. 2010; Weed et al. 2015b). Warming 

climate will also influence host tree distribution across the 

Northern Rockies region, and tree vigor, which affects susceptibility to bark beetle attack (Chapman et al. 2012; Hart et 

al. 2013).

Bark Beetles in the Northern Rockies

Bark beetles are relative specialists, feeding on a single 

tree species or several species within a single genus. In the 

Northern Rockies region, multiple tree species are affected by 

different bark beetle species (table 8.3). Populations of several beetle species, and MPB in particular, began building in 

1999, with high populations continuing in some areas through 

2013 (USDA FS n.d.) (figs. 8.6, 8.7). Trend analysis indicates 

that most subwatersheds have declining populations, although 

some specific locations had increases in 2012 and 2013 

Figure 8.6—Area (acres) affected by 

bark beetles in the U.S. Forest 

Service Northern Region. Data based 

on Forest Health Protection aerial 

detections surveys.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
326 USDA Forest Service RMRS-GTR-374. 2018 Figure 8.7—Cumulative area affected by mountain pine beetle between 1999 and 2013 in the Northern Rockies. Data based on Forest Health Protection aerial detection surveys.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 327

(Egan 2014; Egan et al. 2013). Based on 2012 vegetation 

characteristics, susceptibility of Northern Rockies watersheds 

to future MPB outbreaks is spatially variable with many areas 

projected to lose more than 25 percent of total basal area 

(Krist et al. 2014).

Drivers of Bark Beetle Outbreaks

Bark beetle population outbreaks require forests with extensive host trees of suitable size and age (Fettig et al. 2013). 

For most irruptive species, preferred hosts are large, mature 

trees that provide a large amount of phloem resource for a 

developing brood. Large landscapes of these mature stands 

provide ideal conditions for years of bark beetle population 

growth.

Although suitable host trees are critical to outbreak development, beetle populations can exist for years at low levels 

until release is triggered by inciting factors. These triggers 

allow for rapid population growth that utilizes plentiful host 

trees. Triggers have been difficult to quantify but include factors that make food more readily available and that increase 

survival and reproduction of the beetles. Stand conditions 

(Fettig et al. 2013), drought (Chapman et al. 2012; Hart et al. 

2013), and pathogens (Goheen and Hansen 1993) can make 

it easier for low levels of beetles to overwhelm and kill trees. 

Similarly, large areas of host trees recently killed by fire, 

wind, or avalanche provide pulses of accessible food, and 

have resulted in outbreaks of some species such as Douglasfir beetle (Dendroctonus pseudotsugae) and spruce beetle 

(D. rufipennis) (Hebertson and Jenkins 2007; Shore et al. 

1999), as well as secondary beetles including Ips species and 

fir engraver (Scolytus ventralis) (Livingston 1979). Weather 

favorable to beetle reproduction and survival also influences 

population fluctuations, and can both initiate and sustain outbreaks (Bentz et al. 2011; Powell and Bentz 2009; Régnière 

and Bentz 2007).

Given a susceptible forest, climate and weather directly 

drive bark beetle outbreaks by affecting beetle growth and 

survival through temperature-dependent life history traits. For 

example, the process of mass attack needed to successfully 

overcome tree defenses requires synchronous emergence 

of adults, a process mediated by temperature (Bentz et al. 

1991). Diapause and development rate thresholds help in 

this synchrony (Bentz and Jönsson 2015; Hansen et al. 2001, 

2011; Ryan 1959; Safranyik et al. 1990). These strategies also 

reduce the likelihood that life stages most sensitive to cold 

(eggs and pupae) are not present during winter. Development 

rates and thresholds also dictate life cycle timing, an important determinant of the number of generations per year.

The western pine beetle (D. brevicomis) and Ips species 

can be bivoltine (two generations in one year) in the Northern 

Rockies (Kegley et al. 1997; Livingston 1991), although 

multivoltine in more southern parts of their range. Other bark 

beetle species need at least 1 year to complete a generation 

(univoltine), and at higher elevations, where temperatures are 

cooler, 2 to 3 years may be required for a complete life cycle. 

Warm temperatures in the summer and spring extend the time 

that temperatures are above development thresholds, thereby 

allowing a reduction in generation time (Bentz et al. 2014; 

Hansen et al. 2001). Shorter generation times can lead to 

increased population growth, causing increased tree mortality. 

Winter temperature also influences bark beetle population 

success. Larvae cold-harden to survive subfreezing temperatures (Bentz and Mullins 1999; Miller and Werner 1987), 

although extreme fluctuations in temperature in spring and 

fall, in addition to long durations of temperatures below –31 

°F, can cause extensive larval mortality (Evenden and Gibson 

1940; Régnière and Bentz 2007; Safranyik and Linton 1991).

Bark Beetle Outbreaks Shape 

Landscape Patterns

Bark beetle disturbances play a significant role in successional pathways and biogeochemical cycles in Northern 

Rockies forests (DeRose and Long 2007; Edburg et al. 2012; 

Hansen 2014). At low population levels, bark beetles act locally 

as thinning agents, producing forest gaps that promote regeneration and the release and subsequent growth of neighboring 

host and nonhost trees, often producing uneven-aged stands 

(Mitchell and Preisler 1998). At outbreak population levels, 

tree mortality can approach 80 percent across landscapes of 

homogeneous host species and age, changing age-class distributions and overstory and understory species compositions. 

For example, in seral lodgepole pine forests, removal of the 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region

Table 8.3—Bark beetle species that cause economic impacts in the Northern Rockies.

Bark beetle species

Common name Scientific name Host tree species

Western pine beetle Dendroctonus brevicomis Ponderosa pine

Mountain pine beetle D. ponderosae Limber pine, lodgepole pine, ponderosa pine, 

western white pine, whitebark pine

Douglas-fir beetle D. pseudotsugae Douglas-fir

Spruce beetle D. rufipennis Engelmann spruce

Pine engraver beetle Ips spp. Lodgepole pine, ponderosa pine, western white pine

Fir engraver Scolytus ventralis Grand fir
328 USDA Forest Service RMRS-GTR-374. 2018

largest trees by MPB can hasten succession by climax species 

when fire is absent (Hagle et al. 2000; Roe and Amman 1970). 

Bark beetle disturbance can have long-term effects on forest 

structure and composition (Pelz and Smith 2012), and future 

landscape patterns in some forest types will be driven by tree 

mortality caused by large outbreaks of beetles.

Potential Future Bark Beetle Regimes 

and Occurrence

Climate change will have indirect and direct effects on 

bark beetle population outbreaks (table 8.4). Indirectly, 

changing temperature and precipitation regimes will influence the suitability and spatial distribution of host trees. 

Community associates important to bark beetle population 

success, including fungi, predators, and competitors, will also 

be affected by changing climate and thereby indirectly affect 

beetle population outbreaks. Direct effects will also occur 

as changing temperature regimes either promote or disrupt 

bark beetle temperature-dependent life history strategies 

that evolved through local adaptation for increased beetle 

population fitness and survival. Future bark beetle-caused 

tree mortality will therefore depend not only on the spatial 

distribution of live host trees and heterogeneity of future 

landscapes (see Chapter 6), but also on the ability of beetle 

populations and their associates to adapt to changing conditions when existing phenotypic plasticity is surpassed.

Projected changes in temperature and precipitation, in 

addition to a potential increase in extreme events such as 

windstorms, will significantly influence the spatial and 

temporal distribution of suitable host trees across future 

landscapes. For example, host tree defenses can be weakened 

by reduced water availability (Chapman et al. 2012; Gaylord 

et al. 2013; Hart et al. 2013). Increasing temperature is also 

associated with changing hydrologic regimes (see Chapter 4), 

including altered interseasonal timing of soil water availability facilitated by snowpacks that have progressively melted 

earlier in recent decades, and changes in the distribution 

of precipitation falling as rain versus snow (Regonda et al. 

2005). These factors, along with other potential climate 

changes, may exacerbate physiological drought stress in host 

trees, which could indirectly benefit bark beetles that colonize 

stressed hosts in the late spring or summer (Raffa et al. 2008). 

Similarly, increased wind events could provide a reservoir of 

stressed trees used by some bark beetle species to surpass the 

endemic-epidemic threshold. Species currently considered 

secondary (i.e., those that infest stressed trees) could become 

primary tree killers as their favored habitat increases.

Warming temperatures will also directly influence bark 

beetle population success, although the effects will depend on 

the beetle species, as well as the seasonal timing, amount, and 

variability of thermal input. For example, across MPB habitats in the western United States from 1960 to 2011, minimum 

temperatures increased 6.5 °F. This increase in minimum 

temperature resulted in an increase in MPB survival and 

subsequent beetle-caused tree mortality in many areas of the 

Northern Rockies (Weed et al. 2015a). As climate continues 

to change, however, extreme within-year variability in winter 

warming could be detrimental to insect survival. Bark beetles 

produce supercooling compounds as temperatures decrease 

and catabolize compounds as temperatures warm. Large 

temperature fluctuations could result in excessive metabolic 

investment in maintaining appropriate levels of antifreeze 

compounds, leaving individuals with minimal energy stores 

at the end of winter. In addition, many species overwinter at 

the base of tree boles, gaining protection from predators and 

excessive cold temperatures when insulated beneath snow. 

Reduced snow levels in a warming climate could therefore 

add to increased overwinter mortality.

Warming at other times of the year could similarly have 

both positive and negative effects on bark beetle populations. 

Phenological flexibility allows some species to shift voltinism 

pathways, developing on a semivoltine (one generation 

every 2 years) life cycle in cool years, and a univoltine life 

cycle in warm years (Bentz et al. 2014; Hansen et al. 2001). 

Warming temperatures could also cause species that are 

Table 8.4—Risk assessment for mountain pine beetle outbreaks.a

Elevation Direction of change Main driver(s) of change Projected duration of change

Likelihood of 

change

<3,300 ft Increase if host trees 

available

Temperature–caused shift to 

bivoltinismb

Increasing risk through 2100 High

3,300–6600 ft Decrease Temperature-caused disruption of 

seasonality

Decreasing risk through 2100 High

6,600–10,000 ft Increase initially, then 

decrease

Initially temperature-caused shift 

from semivoltinec to unvioltined, 

then disruption of seasonality

Decreasing risk through 2100 High

>10,000 ft Increase Temperature-caused shift from 

semivoltine to univoltine

Increasing risk through 2100 High

a Developed using model simulations and expert opinion and information from literature as summarized in this chapter.

b Two generations in one year.

c One generation in two years.

d One generation in one year.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 329

currently bivoltine (e.g., western pine beetle, Ips species) to 

become multivoltine. These types of voltinism shifts can lead 

to rapid increases in beetle populations and subsequent tree 

mortality. Some thermal regimes allow these life cycle shifts 

yet maintain seasonal flights. However, other thermal regimes 

that result in voltinism shifts could also disrupt seasonality. 

For example, warm summers could accelerate development, resulting in reduced generation time, but could also 

result in cold-sensitive life stages entering winter. Existing 

developmental thresholds and diapause strategies that serve 

synchrony currently reduce the likelihood of this happening. 

As existing phenotypic plasticity is surpassed, rapid warming 

without adaptation could lead to lower overall population 

fitness in some areas as a result of poor seasonal timing 

(Régnière et al. 2015).

Expected Effects of Climate Change

Although many bark beetle species in the Northern Rockies 

region can cause economic impact, the influence of climate 

change on population outbreaks has been most studied in MPB. 

It is clear that multiple aspects of climate change can positively 

influence MPB, including increasing winter temperature 

(Régnière and Bentz 2007; Weed et al. 2015b) and reduced precipitation (Chapman et al. 2012). But changing thermal regimes 

can have both positive and negative effects on MPB population growth through phenological synchrony and generation 

timing. Acknowledging potential other climate effects, here we 

describe expected direct effects of climate change using a temperature-dependent mechanistic demographic model of MPB 

population growth that is based on phenological synchrony 

(Powell and Bentz 2009). The effect of future temperatures on 

univoltine population growth rate relative to historical conditions is projected. Although current climates apparently prevent 

MPB from successfully completing two generations in a single 

year (Bentz and Powell 2015; Bentz et al. 2014), we also evaluated if future thermal regimes would promote bivoltinism. The 

model was driven with downscaled temperatures from two 

global climate models (GCMs: CanEMS2, CCSM4) and two 

emissions scenarios (Representative Concentration Pathways 

RCP 4.5 and RCP 8.5) based on the multivariate adaptive constructed analogs approach (University of Idaho n.d.). Although 

indirect effects of climate clearly affect host tree vigor, stand 

composition, and distribution across a landscape, these effects 

are currently not included in our demographic model. We 

report our model results, however, in conjunction with hazard 

categories developed by Krist et al. (2014) based on stand 

conditions conducive to MPB population growth (table 8.5). 

Model output was considered only for locations where pines 

currently grow. Model projections are presented in figures 8.8 

and 8.9, and tables 8.4 and 8.5, and are summarized next. 

See Bentz et al. (2016) for spatial displays (for the CanEMS2 

GCM).

Table 8.5—Pine and mountain pine beetle (MPB) metrics by elevation category. Pine forests <6,600 ft have relatively low current 

hazard for MPB and low univoltine growth potential, although bivoltine potential is moderate. Pine forests >6,600 ft have 

relatively high current stand hazard conditions for MPB and relatively high univoltine growth potential, although bivoltine 

potential is zero.

<3,300 ft 3,300–6,600 ft 6,600–10,000 ft >10,000 ft

Current stand density pine (trees per acre [standard 

deviation])a 46.4 (58.7) 142 (206) 471 (434) 223 (223)

 Proportion of area (percent) b rated as:

 Low hazard 97 69 30 18

 Moderate hazard 2 13 14 13

 High hazard 1 18 56 68

MPB potential for population success (2015–2025), 

based on simulation with CanEMS2 GCM, emission 

scenario RCP-45

 Univoltine population growth rate (R) 0.00 0.44 1.62 0.65

Bivoltine (percent of points within elevation 

category projected to have a thermal regime 

supporting bivoltinism for >50 percent of years 

between 2015 and 2025)

24 5 0 0

MPB potential for population success (2015–2025), 

based on simulation with CanEMS2 GCM, emission 

scenario RCP-85

 Univoltine population growth rate (R) 0.04 0.86 2.0 1.05

 Bivoltine (as above) 35 7 0 0

a From Blackard et al. (2009).

b Current MPB hazard based on host stand conditions (from Krist et al. 2014).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
330 USDA Forest Service RMRS-GTR-374. 2018

The proportion of areas with thermal requirements for 

MPB bivoltinism has historically been low in the Northern 

Rockies region (figs. 8.8, 8.9). Stands at elevations less 

than 3,300 feet currently have relatively few pines and low 

hazard to MPB, and population growth of univoltine populations was historically very low. This is most likely because 

it was too warm, and adult emergence synchrony was 

disrupted. Growth rate is projected to decrease further in 

current (2000–2009) and future climates relative to historical periods (fig. 8.8). However, the proportion of simulation 

points at less than 3,300 feet with thermal regimes that 

allow for bivoltinism is projected to increase through 2100, 

particularly when the RCP 8.5 scenario temperature projections are used (fig. 8.8). The availability of pines at less than 

3,300 feet in future climates may be restricted.

• Pine stands at 3,300 to 6,600 feet were also projected 

to have lower univoltine population growth rates 

in current and future climates than historically, and 

some small proportion of stands will have increasing 

probability of bivoltinism (fig. 8.8).

• The highest density of pine currently occurs at 6,600 

to 10,000 feet, the elevation range also associated 

with most (56 percent) of the high-hazard stands 

(table 8.5). These stands are predicted to have higher 

univoltine population growth rates than historically, 

through 2030–2050. Thermal regimes for bivoltinism 

are unlikely at this elevation (fig. 8.8).

• Population growth rates were historically very low in 

stands above 10,000 feet until 2000–2009; rates are 

projected to increase through 2100 (fig. 8.8). These 

stands historically were too cool for bivoltinism and 

are projected to remain too cool in future climates.

• Pine forests below 6,600 feet currently have low stand 

hazard for MPB and low univoltine growth potential 

in the near future (2015–2025), although bivoltine 

potential is moderate. Pine forests above 6,600 feet 

have high current stand hazard for MPB and high 

univoltine growth potential between 2015 and 2025, 

although bivoltine potential is zero. Pine stands above 

6,600 feet, particularly between 6,600 and 10,000 feet, 

have the highest risk of MPB-caused tree mortality in 

the near future.

• The Grassland subregion contains a small amount 

of “Great Plains ponderosa pine,” and historically 

temperatures were too warm for univoltine MPB 

population success (fig. 8.9). A high proportion 

of locations in these areas is projected to become 

thermally suitable for bivoltinism (fig. 8.9), although 

pine occurrence in future climates may be limited.

• In the Western Rockies, Central Rockies, and Eastern 

Rockies subregions, univoltine population growth 

is projected to decrease beginning in the 2000–2009 

period, although a small proportion of locations at the 

lowest elevations will become thermally suitable for 

bivoltinism by 2080–2100.

• In the Greater Yellowstone Area subregion, univoltine 

population growth remains relatively high until 

the 2080–2100 time period (fig. 8.9) with a small 

proportion of locations at the lowest elevations with 

the potential to become bivoltine at that time (fig. 8.9).

Interactions with Other Disturbance 

Processes

Bark beetle-caused tree mortality is influenced by and 

can influence fire, although the relationships are complex 

and dynamic (Hicke et al. 2012; Jenkins et al. 2014). In fact, 

any disturbance that influences the distribution and vigor of 

host trees will influence bark beetle outbreaks. Moreover, 

the pattern of bark beetle-killed trees across a landscape 

will have cascading effects on a myriad of abiotic and 

biotic processes such as fire, wildlife habitat, and vegetation succession and dynamics (Saab et al. 2014). During 

non-outbreak years, many bark beetle species survive in 

trees infected with root diseases. The amount of root disease 

in trees stressed by climate change may increase, which in 

turn can result in higher populations of bark beetles causing 

increased tree mortality (see Root Disease section).

Unknowns and Uncertainties

It is important to acknowledge sources of uncertainty 

in models that describe relationships among climate, 

bark beetle populations, and their host trees, in addition to uncertainties with projections of future climate. 

Mechanistic-based phenology models are good tools for 

projecting beetle population response in a changing climate 

(Bentz and Jönsson 2015). This type of model incorporates 

the important role of seasonality and allows for emergent 

population processes when driven by climate change 

projections. However, data are lacking on temperaturedependent relationships of most bark beetle species in the 

Northern Rockies, hindering development of conceptual 

and empirical models. Moreover, one of the greatest sources 

of uncertainty is the lack of understanding of potential 

adaptations in bark beetle developmental traits to a rapidly 

changing climate. With few exceptions (Addison et al. 2013, 

2014), little is also known about climatic effects on the wide 

array of bark beetle community associates including fungi, 

bacteria, parasites, and predators.

Host trees will also respond to climate change, and 

responses will have cascading effects on bark beetle populations. Further investigation, especially in water-limited 

systems, is needed to increase quantitative understanding 

of how climate-induced changes in trees influence bark 

beetle population success at different spatial scales. Due 

to this limited understanding, predictive models that incorporate the integrated effects of climate and bark beetle 

disturbances on vegetation pathways are lacking, constraining our ability to make projections for future forests 

(Anderegg et al. 2015).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 331

Figure 8.8—Left panel: projected mountain pine beetle (MPB) population growth rate (mean, standard deviation) of univoltine 

populations (one generation per year) over decades (historical) and 20-year periods (projected) from 1950 to 2100. Shown 

are the mean and standard deviation among locations of decadal (historic) and 2-decadal (projected) growth rates. Right 

panel: proportion of simulation points in which bivoltinism (two generations in one year) is projected for more than 50 

percent of years in each time period. Projections are based on a temperature-dependent model of MPB development and 

population growth (Powell and Bentz 2009) using temperatures from the CanESM2 and CCSM4 GCMs and two emission 

scenarios (Representative Concentration Pathways [RCP] 4.5 and 8.5). Model output is shown by elevation category (in feet). 

Simulation points are geographic locations of downscaled temperatures where pines occur (sample size = 17,616).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
332 USDA Forest Service RMRS-GTR-374. 2018

Figure 8.9—Left panel: Projected mountain pine beetle (MPB) population growth rate (mean, standard deviation) of univoltine 

populations (one generation per year) over decades (historical) and 20 year periods (projected) from 1950 to 2100. Shown are 

the mean and standard deviation among locations of decadal (historic) and 2-decadal (projected) growth rates. Right panel: 

proportion of simulation points where bivoltinism (i.e., two generations in one year) is projected for more than 50 percent of 

years in each time period. Predictions are based on a temperature-dependent model of MPB development and population 

growth (Powell and Bentz 2009) using temperatures from the CanESM2 and CCSM4 GCMs and two emission scenarios (RCP 

4.5, RCP 8.5). Model output is shown by Northern Rockies Adaptation Partners (NRAP) subregion. Simulation points are 

geographic locations of downscaled temperatures where pines occur (sample size = 17,616).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 333

White Pine Blister Rust

Overview

White pine blister rust (Cronartium ribicola, hereafter 

referred to as WPBR) is a nonnative fungus that was inadvertently introduced to western North America from Europe 

around 1910 (Bingham 1983; Tomback and Achuff 2011). 

The WPBR fungus infects only five-needle pine species, and 

all nine North American white pine species are susceptible. 

Three white pines occur in the Northern Region: western 

white pine (Pinus monticola), whitebark pine (Pinus albicaulis), and limber pine (Pinus flexilis). WPBR has been found 

across most of the ranges of these three pines in the Northern 

Region, and it has caused greater than 90-percent mortality 

in western white pine. WPBR presence in whitebark and limber pine is variable, but highest in the warmer, moister parts 

of their ranges (Tomback and Achuff 2010).

The life cycle of WPBR requires two hosts, with two 

spore-producing stages on white pine and three separate 

spore-producing stages on three potential alternate hosts: 

Ribes, Pedicularis, and Castilleja species. Pine infection 

begins when basidiospores produced on Ribes leaves in late 

summer are wind dispersed to nearby pines. The basidiospores germinate on pine needles and fungal hyphae grow 

through the stomata into the cell tissues, needles, and stem 

(Patton and Johnson 1970).

Cankers form on white pine branches and main stems 

as the phloem is first invaded by hyphae and then becomes 

disrupted by blister-like structures that are filled with 

powdery yellow aeciospores (Hudgins et al. 2005). As tree 

branches and stems are girdled, branches and tops die back 

to the canker. Continued downward growth of the persistent 

cankers and poor competitive ability then kill infected trees. 

Depending on where the canker occurs, cone production 

often decreases or is prevented well before tree death.

The released aeciospores infect Ribes and the other alternate host species (Schwandt et al. 2013). This can occur at 

long distances from infected pines, as aeciospores are hardy 

and can disperse as much as 60 miles (Frank et al. 2008). At 

most locations and for most alternate hosts, infected leaves 

produce urediniospores that spread only short distances 

from leaf to leaf or plant to plant (Newcomb 2003). These 

recurrent infections keep rust alive through the growing 

season until conditions are suitable for pine infection. For 

most alternate hosts, leaf infections produce hair-like structures (teliospores) that produce basidiospores in fall or when 

night temperatures are cool; other hosts with less vigorous 

leaf infections may produce teliospores directly. Locations 

where synergistic pairs of alternate hosts occur—one that 

readily spreads urediniospores, and one that produces pineinfecting basidiospores—are especially favorable for pine 

infection (Zambino 2010).

Basidiospores have a narrow weather window for 

production, dispersal, and successful infection of pine 

needles: they infect best in periods of high humidity (>98 

percent) with moderate temperatures (between 60 and 68 

oF) (Bega 1960). Conditions for infection are determined by 

temperature, with a 48-hour optimum for infection at 64 oF, 

though up to 5 days may be required at 39 oF (McDonald et 

al. 1981). Temperatures exceeding 77 oF are lethal for teliospores. Basidiospores are short-lived and most often cause 

infections within a few feet of Ribes plants, but they can be 

carried long distances or upslope on moist air masses, lofted 

in thermals over bodies of water, or carried downslope on 

cold air currents to infect trees at the interfaces with temperature inversions (Van Arsdel et al. 2005; Zambino 2010).

The time required for WPBR to kill its host varies by 

species, distance of infection from bole (Schwandt et al. 

2013), and bole circumference. Typically WPBR kills 

western white pine in 5 to 10 years, and whitebark pines 

(P. albicaulis) after 20 years (Hoff and Hagle 1990). WPBRcaused tree mortality greatly affects stand structure and 

species composition, but the most serious impact of WPBR 

is the long-term impact on white pine regeneration capacity, with direct mortality of rust-susceptible seedlings and 

saplings and the loss of cone and seed production following 

branch dieback and top kill. Native pine populations show 

some heritable resistance to WPBR, but the frequency of 

resistance is low and variable (Zambino and McDonald 

2004). Studies in the 1970s of natural stands that originated 

in the late 1920s estimated that fewer than 1 in 10,000 trees 

lacked cankers (were rust-resistant) (Hoff et al. 1980). But 

resistance may have increased in the 35 years since this 

Table 8.6—Risk assessment for white pine blister rust.a

Direction of 

change Main driver(s) of change

Predicted duration 

of change

Likelihood of 

change

Infection frequency 

and severity

Little to moderate 

Increase

Possibility of increased 

wave years in high elevation 

ecosystems

Until a sufficient 

proportion of the 

landscape has 

populations of rustresistant pine trees, 

there will always 

be high infections 

regardless of climate

Low

a Developed using expert opinion and information from literature as summarized in this chapter.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
334 USDA Forest Service RMRS-GTR-374. 2018

report, as a result of additional rounds of regeneration under 

natural selection (Klopfenstein et al. 2009; McDonald et al. 

2004, 2005; Zambino and McDonald 2005).

Effects of Climate Change on White 

Pine Blister Rust

Climate changes may cause WPBR infections to 

occur earlier and with greater incidence in pine stands 

(table 8.6). Specific weather conditions required for basidiospore germination and infection of pine needles may 

occur more frequently and for longer periods in the future 

(Koteen 1999). “Wave” years are projected to increase in 

the future for whitebark pine (Keane et al. in press); these 

years have hot and humid weather conditions throughout 

most of the growing season that facilitate infections on 

pine and alternate hosts, followed by moist but cooler 

weather events for teliospore and basidiospore production 

and pine infection. For most temperate pine forests (western white and limber pine), however, Sturrock et al. (2011) 

speculate that wave years will actually decrease because 

of hotter, drier projected climates. Further, Helfer (2014) 

suggests that warmer temperatures could negatively affect 

rusts and that higher concentrations of atmospheric carbon 

dioxide (CO2) could cause declines in rust populations. He 

also states that the highly variable and extreme weather 

projected in the future will aid in WPBR spore dispersal, 

resulting in expansion of its range and higher spore loads 

on existing pines.

The highly variable and novel climatic conditions 

projected in the future may serve to accelerate mutations 

of WPBR to create populations that may overcome the native rust resistance in five-needle pines (Simberloff 2000). 

Alternatively, changing climates may lead to suitable 

climates for WPBR variants that are in locations other than 

North America. Most rust infection and mortality occur 

regardless of tree condition and vigor, so it is doubtful 

that any direct responses of the tree or the Ribes hosts to 

future climates, such as increased growth, will enhance 

or degrade the ability of the host to ward off infections. 

However, climate-mediated changes in host regeneration 

dynamics could restrict or expand host ranges (Helfer 

2014). As a result, this could alter WPBR range. Some 

predict higher leaf biomass for the two host species with 

warmer, enriched CO2 environments, and more leaves 

could provide additional germination surfaces and a higher 

chance for rust infection on both hosts.

Distribution and frequency of synergistic alternate host 

species combinations (Zambino 2010) could also change. 

In higher elevation areas, new climates (i.e., warming 

temperatures along with high precipitation) may facilitate 

the expansion of Ribes into areas that were historically 

too cold and snowy to support certain hosts. On the other 

hand, in low-elevation upland areas where Ribes is currently abundant, drought may cause decline of the host. 

Moreover, drought may cause extended and extensive 

stomatal closure in the pines, thus preventing hyphae entry. 

The shifting of mosaics of the Ribes host populations into 

new higher elevation areas, driven by drought in lower 

elevations, may spread WPBR into areas where it has not 

yet occurred.

Interactions with Other Disturbance 

Processes

The interaction of fungal pathogens and their hosts with 

other disturbances may be a key factor in future WPBR 

infections (Ayres and Lombardero 2000). The interactive effects of wildland fire on WPBR are probably most 

important, but they are mostly minor and primarily indirect 

under future climates. The exception is the possibility that 

smoke may kill rust spores produced at the time of the fire 

(Hoffman et al. 2013).

White Pine Blister Rust and Wildland Fire

Fire indirectly affects WPBR by changing the size, 

distribution, and abundance of its hosts. Most five-needle 

pines of the western United States are somewhat fireadapted with thick bark, high canopies, and deep roots 

(Ryan and Reinhardt 1988). Mixed- and high-severity fires 

are currently common in most forests where WPBR is 

present (Arno et al. 2000; Murray 2007) and are projected 

to increase in size, frequency, and intensity (Westerling 

et al. 2011). Increases in fires and burned areas can create 

favorable conditions for pine regeneration because most 

five-needle pine seeds are dispersed by rodents and birds 

and are thus better adapted to spread into postfire landscapes than seeds of their tree competitors (Lanner 1989; 

Morgan et al. 1994). Ribes populations may increase after 

fire through regeneration by seed and sprouting from roots 

and rhizomes. Therefore, fire will often favor Ribes regeneration over other species not adapted to fire. However, 

re-burns soon after an initial fire can eliminate regenerating Ribes individuals before they can develop a seedbank 

for the next forest regeneration cycle (Zambino 2010).

Severe fires that kill rust-resistant pine trees may ensure 

continued high rust mortality in the future because it 

dampens the rate of rust-resistant adaptations (Keane et al. 

2012). However, where rust-resistant five-needle pines survive fire they can provide the seeds for populating future 

landscapes that are resilient to both rust infection and fire 

mortality. Fire exclusion generally increases competition 

stress (Heward et al. 2013), weakening pine trees. Stress 

from competition does not increase rust infection (Parker 

et al. 2006), but may facilitate mortality in pines trees 

under stress after being girdled by blister rust.

Trees infected with WPBR are weakened, and may 

be more susceptible to fire-caused damage and mortality 

(Stephens and Finney 2002). Ladder fuels of trees attacked or killed by WPBR may increase crowning owing 

to abundant pitch, which can extend from base to rust 

bole cankers, and from dead red crowns of girdled trees. 

As branches and tops of white pines die back, they add 

dead foliage and wood to the fuelbed, which may increase 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 335

fire intensity and fire-caused tree mortality. In contrast, 

western white pine needles gradually added to the fuel bed 

are more similar to normal needle shed, and are quickly 

degraded in moist, productive environments. Mortality 

from WPBR often results in the elimination or thinning 

of the shade-intolerant pine overstory, allowing shadetolerant competitors to occupy the openings. This creates 

substantially different canopy fuel conditions, such as 

lower canopy base heights, higher canopy bulk densities, 

and greater canopy cover, which facilitate more frequent 

and intense crown fires (Keane et al. 2002; Reinhardt et 

al. 2010). Many shade-tolerant competitors are also more 

susceptible to fire damage, resulting in higher postfire tree 

mortality in rust-infected landscapes.

White Pine Blister Rust and 

Mountain Pine Beetle

Interactions between native MPB populations and 

WPBR are rarely studied because they are difficult to 

quantify over time. In their endemic phase, MPB populations may weaken pines and facilitate infection by WPBR, 

but these interactions are strongly governed by climate 

and biophysical environment (Tomback and Achuff 2011). 

However, the ubiquitous presence of WPBR spores and the 

resistance to the disease in pine species ensure that most 

five-needle pines at many sites will eventually become 

infected and die from WPBR, regardless of MPB endemic 

levels (Hoff et al. 2001). More importantly, MPB influences WPBR through regulation of the tree species that 

are host to both disturbance agents and killing of host trees 

that are resistant to the rust (Campbell and Antos 2000). 

For example, although whitebark pine stands in the Greater 

Yellowstone Area show little WPBR-related mortality, levels of MPB-related mortality are high (Kendall and Keane 

2001; Macfarlane et al. 2013). Many stands of healthy 

five-needle pines in Yellowstone have been subjected to 

a major MPB outbreak over the last decade as a result of 

high densities of large diameter trees coupled with prolonged warm, dry conditions. These outbreaks resulted in 

substantial mortality of rust-resistant whitebark pine trees 

(Logan et al. 2008).

Effects of WPBR on MPB infestations are also highly 

variable and subtle. Archibald et al. (2013) found less MPB 

activity in trees that had high WPBR damage, whereas 

Bockino and Tinker (2012) found that whitebark pine 

selected as hosts for MPB had significantly higher WPBR 

infection, but this varied by tree size (diameter), stand type, 

and disturbance pattern (Larson 2011). Kulhavy et al. (1984) 

found that more than 90 percent of western white pine trees 

infected by bark beetles had either WPBR or some type of 

root disease, whereas Six and Adams (2007) found little 

evidence of interaction effects between MPB and WPBR. 

Simulations of MPB disturbance under current climate result in a decline in both lodgepole pine and whitebark pine, 

and a corresponding increase in subalpine fir (Abies lasiocarpa) and Douglas-fir (Pseudotsuga menziesii), with little 

change from the addition of WPBR (fig. 8.10). These trends 

are enhanced under a warmer climate, in which lodgepole 

pine declines are greater and stands are replaced primarily 

by Douglas-fir, but WPBR interaction has only minor effects 

on species composition (Keane et al. 2015).

White Pine Blister Rust, Fire, 

and Mountain Pine Beetle

Studies of interactions among fire, beetles, and rust are 

rare, but we posit that MPB and WPBR serve to reduce 

five-needle pine populations and create fuelbeds that may 

support wildfires that are more intense than historical 

counterparts, potentially resulting in high mortality of the 

dominant vegetation. Although fire reduces pine abundance 

in the short term, it apparently ensures the long-term 

persistence of pine by eliminating competitors (Keane and 

Morgan 1994). Modeling studies have shown that decades 

to centuries are required to reestablish populations of rustresistant white pines after die-off (such as would occur with 

MPB), and increased frequency and extent of wildfire under 

climate change favored white pine regeneration and persistence over shade-tolerant species in some regions, even 

with WPBR infection and losses of some white pine to fire 

(Loehman et al. 2011a,b). The largest decline in whitebark 

pine has been found in those areas affected by both WPBR 

and MPB, but not fire (Campbell and Antos 2000).

Interactions among fire, MPB, and WPBR can occur 

only in areas that have the potential to support five-needle 

pines, which are rare in many landscapes. However, recent 

simulation efforts have found that fire frequency under current climate is 10 percent lower when all three disturbances 

are allowed to interact, and average tree mortality is also 

lower (fig. 8.10). In a warmer climate, fire frequency decreases, high-severity fires increase, and interactions among 

disturbances create different landscapes than when each disturbance acts separately (or in the absence of disturbance) 

(Keane et al. 2015) (fig. 8.11).

Unknowns and Uncertainties

It is difficult to mechanistically simulate WPBR population dynamics because the disease is governed by processes 

from fine-scale (e.g., microclimate, spore production and 

germination, tree size and health) to coarse-scale (e.g., spore 

dispersal, wind, alternate host distributions, topographic 

controls) processes. Therefore, the representation of WPBR 

in most models will tend to be both stochastic and empirical, 

and this will tend to reduce the robustness of model predictions and add to the uncertainty of future WPBR predictions.

White pine trees will also directly respond to climate 

change, and responses will have interacting effects on 

WPBR infection potential. The key to the future abundance 

of white pines on the Northern Rocky Mountain landscapes 

will hinge on the ability of the three pine species to develop 

rust-resistant populations that are resilient to climate change. 

This probably will not happen without human intervention. 

The rapid pace of predicted climate change coupled with the 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
336 USDA Forest Service RMRS-GTR-374. 2018

long maturation times of the three pine species may exacerbate the species decline. It is essential that natural resistance 

is fostered by land management agencies to ensure that 

these valuable species and the forests that they create are not 

lost forever.

Forest Diseases

Overview

Forest diseases are found in all forest ecosystems of 

the Northern Rockies region. They are one of three major 

disturbance groups that affect ecosystem development and 

change, but the overall impacts of forest diseases on various resources are difficult to quantify. This is partly due 

to our inability to separate predisposing effects of some of 

the most important diseases, which act over a long term, 

from mortality caused by short-term factors such as insect 

outbreaks and drought. Forest diseases tend to be more 

cryptic and chronic in their effects, so estimating their occurrence and abundance is difficult. Here we rely mostly on 

older studies and observations to quantify disease effects in 

what were formerly called commercial timberlands. Spatial 

distributions of most forest diseases have not changed much, 

although the effects of individual diseases may change due 

Figure 8.10—Landscape composition of species cover types using the plurality of basal area for current 

climate for the East Fork of the Bitterroot River landscape with all combinations of fire, white pine 

blister rust (WPBR), and mountain pine beetle (MPB): (a) fire, WPBR, and MPB; (b) no fire, WPBR, 

MPB; (c) fire and MPB; (d) MPB only; (e) fire and WPBR; (f) WPBR only; (g) fire only; and (h) no 

disturbances. Species: PIAL-whitebark pine, PIEN-Engelmann spruce, ABLA = subalpine fir, PICOlodgepole pine, PSME-Douglas-fir, and PIPO-ponderosa pine. Produced using the FireBGCv2 

mechanistic ecosystem-fire process model (Keane et al. 2015).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 337

to effects of climate on disease organisms, hosts, and environmental predisposition.

We focus on the major groups of forest diseases in the 

Northern Rockies known to have significant effects on ecosystems and ecosystem services, and for which at least some 

information is available on effects of climate.

Dwarf Mistletoe

Dwarf mistletoes (Arceuthobium spp.) are a group of 

parasitic seed plants that are widespread across the Northern 

Rockies region and primarily cause reduced tree growth 

and productivity, but in some cases also cause tree mortality. Five species of dwarf mistletoe are found in the region, 

mostly on these primary hosts: A. americanum on lodgepole 

pine, A. campylopodum on ponderosa pine, A. cyanocarpum

on limber pine, A. douglasii on Douglas-fir, and A. laricis

on western larch (Larix occidentalis). Mistletoes may occasionally infect trees of other species when they are growing 

interspersed with infected primary hosts.

Approximately 28 percent of lodgepole pine forest is 

infested by A. americanum. Arceuthobium cyanocarpum

occurs primarily east of the Continental Divide, although 

the area affected has not been estimated. Douglas-fir is 

infested in more than 13 percent of its range by A. douglasii. 

About 38 percent of the western larch type is infested by A. 

laricis. The distribution of A. campylopodum in the region is 

Figure 8.11—Landscape composition of species cover types using the plurality of basal area for a warmer 

climate (A2 emission scenario) for the East Fork of the Bitterroot River landscape with all combinations 

of fire, white pine blister rust (WPBR), and mountain pine beetle (MPB): (a) fire, WPBR, and MPB; (b) 

no fire, WPBR, MPB; (c) fire and MPB; (d) MPB only; (e) fire and WPBR; (f) WPBR only; (g) fire only; 

and (h) no disturbances. Species: PIAL = whitebark pine, PIEN = Engelmann spruce, ABLA = subalpine 

fir, PICO = lodgepole pine, PSME = Douglas-fir, and PIPO = ponderosa pine. Produced using the 

FireBGCv2 mechanistic ecosystem-fire process model (Keane et al. 2015).

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
338 USDA Forest Service RMRS-GTR-374. 2018

limited to a portion of Idaho, where it occurs on ponderosa 

pine. Drummond (1982) estimated that 2.1 million acres of 

national forest lands were infested by the three most important species of dwarf mistletoe in the Northern Rockies. An 

estimated 31 million cubic feet of wood are destroyed by 

these pathogens each year.

Root Disease

Root disease is a major cause of tree growth loss and 

mortality in the Northern Rockies region. These diseases are 

primarily a problem west of the Continental Divide, but also 

affect local areas east of the divide. Various species of fungi 

cause root disease; the two most important native pathogens 

in the Northern Rockies region are Armillaria species and 

Heterobasidion irregulare, which causes annosus root 

diseases. These and other root diseases co-occur in many 

mesic to moist forests west of the divide. Armillaria root 

disease kills conifers of all species when they are young, 

but is especially damaging to Douglas-fir, subalpine fir, 

and grand fir (Abies grandis) because these species remain 

susceptible throughout their lives (Kile et al. 1991). In addition, root diseases often affect canopy closure and create 

small gaps. The effects of these root pathogens are persistent 

on a site and have impacts on multiple generations of trees. 

Armillaria and other root diseases influence forest species 

composition, structure, and successional trajectories by 

accelerating a transition to species that are more tolerant of 

root disease or by maintaining stands of more susceptible 

species in early-seral stages (Byler and Hagle 2000). They 

can also affect ecosystem services by affecting visual and 

recreational resources.

At least 3.3 million acres in the Northern Rockies have 

moderate to severe root disease, with up to 60 percent 

caused by Armillaria ostoyae (Smith 1984; USDA FS 

2007). A recent evaluation of USFS Forest Inventory and 

Analysis data in the Northern Region identified 2.3 million 

acres of national forest lands with moderate to severe root 

disease (Lockman et al., in preparation). Shrub fields have 

replaced forest cover on 3 percent of forest lands in Idaho 

and Montana as a result of severe root disease. A study 

of Ecosection M333d (Bailey 1983), which includes the 

southern Idaho Panhandle National Forest and southern 

Kootenai National Forest, found evidence of root disease 

on 94 percent of the area (Byler and Hagle 2000). Root 

disease has reduced forest canopy cover in affected stands in 

northern Idaho and western Montana by an average of 20 to 

30 percent.

The National Insect and Disease Forest Risk Assessment 

(Krist et al. 2014) identified locations where significant tree 

mortality and basal area losses from insects and diseases 

could occur between 2013 and 2027, modeling the potential 

for damage in standing live basal area across all ownerships 

from a variety of insects and pathogens. Root disease had 

the highest basal area loss as a percentage of total basal 

area; projected losses ranging from 0 to 20 percent in most 

national forests.

Needle Disease

Needle diseases have historically been of limited significance in the Northern Rockies region; severe infection 

years occur only occasionally, and effects are mostly limited 

to crown thinning and loss of lower branches with some 

mortality of young trees. Needle casts usually cause loss of 

needles in the year following a season that has been favorable for infection. In western larch, needle cast and needle 

blight are observed in the year of infection.

Needle casts and needle blights in lodgepole pine, ponderosa pine, western white pine, Douglas-fir, grand fir, and 

western larch generally cause little damage in the Northern 

Rockies region, although periodic outbreaks can cause 

severe damage in local areas (Lockman and Hartless 2008). 

These diseases are favored by long, mild, damp springs. 

Their occurrence at epidemic levels depends on favorable weather conditions and presence of an adequate host 

population.

Abiotic Disease

Most abiotic diseases result from the effects of adverse 

environmental factors on tree physiology or structure. This 

group of diseases can affect trees directly or interact with 

biotic agents, including pathogens and insects. A number 

of abiotic and environmental factors can affect foliage or 

individual branches, or entire trees, tree physiology, and 

overall tree vigor. The most significant abiotic damage is 

tree mortality.

Forests in the Northern Rockies region are periodically 

damaged by weather extremes, such as temperature and 

drought. Factors such as air pollutants and nutrient extremes 

occur infrequently or locally. An injury known as “red 

belt,” caused by strong, dry, warm Chinook winds in winter 

that induce twig and needle necrosis and desiccation, often 

afflicts conifers on the east side of the Continental Divide, 

primarily Douglas-fir and lodgepole pine (Bella and Navratil 

1987). Drought injury, an abiotic factor that can cause 

disease through loss of foliage and tree mortality, can initiate a decline syndrome by predisposing trees with stressed 

crowns and roots and low energy reserves to infection by 

less aggressive biotic agents, such as canker fungi and secondary beetles. A well-studied decline of western white pine 

called pole blight occurred in the Northern Rockies in the 

1930s and 1940s (Leaphart and Stage 1971). This disease 

occurred on pole-size trees, often in plantations that were 

growing on shallow soils with low moisture storage capacity 

that were exposed to extended drought.

Canker Disease

Canker diseases affect tree branches and boles, typically 

in trees that are poorly adapted to the sites in which they 

are growing. Damage is caused by breakage at the site of 

the cankers, or by mortality of branches and boles beyond 

girdling cankers. Although canker fungi are most active on 

trees under stress, lack of specific data on climate effects 

makes it difficult to infer the effects of climate change.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 339

Broad-Scale Climate Drivers of 

Forest Diseases

Climatic variability and change can alter patterns of 

pathogen distribution and abundance through (1) direct 

effects on development and survival of a pathogen, (2) physiological changes in tree defenses, and (3) indirect effects on 

abundance of natural enemies, mutualists, and competitors 

(Ayres and Lombardero 2000). Sturrock et al. (2011) suggest that climate change will affect pathogens, hosts, and 

their interaction; changes in these interactions may become 

the most substantial drivers of future disease outbreaks.

Fungi cause most forest diseases in the Northern Rockies 

region. Fungus life cycles are significantly influenced by 

climate-related factors such as timing and duration of precipitation, humidity, and temperature for spore germination, 

fungus growth, and inactivation. Fungus life cycles are short 

compared to their hosts, so fungi can respond more rapidly 

to a changing climate than their hosts, with potentially 

serious consequences (Boland et al. 2004). Dwarf mistletoe 

reproduction and infection are also affected by temperature 

and moisture (Hawksworth and Wiens 1996), and dwarf 

mistletoes are generally most prevalent in sites that have 

undergone past disturbances.

Overall health of host trees has a major role in determining if a pathogen successfully infects a tree or kills it. 

Many forest diseases, such as canker diseases, are caused 

by “facultative pathogens” that attack weakened hosts 

under specific environmental conditions. Impacts of climate 

change on host physiology may modify host resistance and 

alter stages and rates of development of pathogens (Coakley 

et al. 1999). Drought, or limited soil moisture availability, is 

a major driver that affects the incidence and severity of facultative pathogens. Soil moisture deficit, flooding, and water 

table fluctuation can all predispose trees to pathogens. Even 

if there are areas that may have a net gain in precipitation, 

projected longer growing seasons could cause recurring water deficit stress. Some diseases may be considered threshold 

diseases; that is, they are damaging but only under certain 

climatic conditions (Hepting 1963). These diseases may 

become more damaging if thresholds that trigger infections 

are reached more frequently, such as in recurring drought.

Effects of Climate Change on 

Forest Diseases

One of the difficulties of predicting sensitivity to a 

changing climate is that the scales available for GCMs, 

pathogen/disease models, and microsite environments 

do not always match (Seem 2004). For example, some 

GCM projections provide only mean monthly and annual 

estimates, rather than daily data useful for modeling forest 

diseases. In addition, pathogen ecology and effects are 

sensitive to local site and environmental conditions that may 

not be well represented by GCMs. There is also considerable uncertainty and lack of knowledge of impacts of a 

changing climate on future forest conditions and interactions 

with pathogens (Woods et al. 2005, 2010). Compared to 

trees, for which available soil moisture is critical, pathogens 

are affected more by precipitation events, especially timing, 

duration, and pattern, all of which are poorly projected by 

climate models. Facultative pathogens respond to weakened 

or less vigorous hosts, and their importance could increase 

if climatic conditions less favorable to tree growth become 

more frequent.

A changing climate will affect forest disease occurrence and severity, through effects on the pathogen, the 

host, or their interaction (Sturrock et al. 2011) (table 8.7). 

Interactions between pathogens and abiotic stressors (e.g., 

temperature and moisture) may represent the most substantial drivers of increased disease outbreaks (Sturrock 2012). 

Epidemics also depend on relatively constrained conditions 

for spread and infection to occur. For example, increased 

drought could affect host susceptibility to pathogens and 

predispose hosts to disease outbreaks (Coakley et al. 1999). 

Although models usually generate mean climatic conditions, 

it is often the extremes that have the greatest influence 

on pest conditions (Hepting 1963). Increased host stress 

Table 8.7—Risk assessment for forest diseases.a

Pathogen 

component

Direction 

of change

Main driver(s) 

of change

Projected duration 

of change

Likelihood 

of change

Needle disease Significant increase if 

appropriate precipitation 

timing occurs

Increased precipitation in 

spring and early summer

May occur sporadically 

in association with 

weather events

High

Root disease Little change Host stress While hosts are 

maladapted

Moderate

Dwarf 

mistletoe

Could decrease mistletoe 

populations

Temperature could influence 

flowering and seed 

production/dispersal

Unknown Low

Abiotic disease Significant increase Temperature and decreased 

precipitation

Unknown High

a Developed using expert opinion and information from literature as summarized in this chapter.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
340 USDA Forest Service RMRS-GTR-374. 2018

could result in increased disease occurrence and interactions among multiple agents (Coakley et al. 1999). There is 

likely to be an increase in declines and dieback syndromes 

(Manion 1991) caused by changes in disease patterns involving a variety of diseases.

A changing climate may indirectly affect competitors, 

antagonists, and mutualists that interact with plant pathogens (Kliejunas et al. 2009). Some of the most profound 

effects of temperature and moisture changes could be on soil 

microflora, and on and in roots and shoots, where a complex 

of organisms live in relationships at the transition between 

pathogenesis, symbiosis, and saprogenesis. The balance 

among organisms could be upset, for example, turning a 

normal mycorrhizal association to pathogenesis, shifting 

pathogens from saprogenic to pathogenic phases, or shifting 

the order of ascendency of competing organisms due to their 

different temperature or moisture optima; consequently a 

pathogen might even take dominance from a saprophyte 

(Hepting 1963). Given that root pathogens of trees can 

often exploit a large food reserve in a tree once a defense is 

breached and then use those reserves to bolster attacks on 

nearby trees, even small changes in the frequency of shifts 

in relationships among fungal communities could have large 

effects.

Despite considerable knowledge about climatic conditions required by specific forest pathogens, little has been 

done to determine how changing climates may affect these 

pathogens (Kliejunas et al. 2009). Recent modeling work by 

Klopfenstein et al. (2009) used a subset of GCMs to project 

how the geographic distribution of the climate envelope for 

Armillaria solidipes and Douglas-fir could change in the 

interior northwestern United States. Their analysis suggests 

that Douglas-fir will have a considerably smaller geographic 

space that matches its current climate envelope and that this 

space will shift, whereas only minor changes are projected 

for A. solidipes. They suggest that areas where Douglas-fir 

is maladapted could increase, which could increase its susceptibility to Armillaria root disease.

Klopfenstein et al. (2009) used information for climatic 

variables based on the current distribution of A. solidipes

on its Douglas-fir host in a network of plots. Climate space 

for A. solidipes modeled for current and 2060 climate are 

shown in figure 8.12. These preliminary projections are not 

necessarily the current or future distribution of A. solidipes, 

but identify only the modeled climate space matching 

where the pathogen currently occurs. It is unknown how the 

climate envelope could change because the distribution of 

competitor fungi and hosts will change as well.

Spring precipitation is projected to increase in most of 

the mountainous area of the Northern Rockies (see Chapter 

3). This may increase frequency and severity of years when 

needle diseases cause significant needle loss in conifer 

species. This could affect the energy balance of susceptible 

trees, with potential effects on yield and vigor, particularly 

for species that normally carry multiple years of needles and 

cannot re-flush later in the season in response to defoliation.

There may be elevation and location maladaptation in 

resistance to the increased needle disease pressure resulting from climate change, as areas of tree host ranges and 

disease occurrences shift in location. Lophodermella needle 

cast in lodgepole pine (caused by Lophodermella concolor) 

occurred in northern Idaho in the early 1980s (Hoff 1985), 

and has also had outbreaks at high elevation in some Idaho 

locations in recent years. Lodgepole pine at high elevation 

normally has only infrequent outbreaks because bud break 

occurs near or after the time when spring rains that favor 

infection have ended, whereas needles in lower elevation 

trees expand when spores are present and able to infect. 

A provenance study under natural conditions during the 

outbreak in the 1980s showed that low elevation populations 

were generally more resistant and had heritable resistance, 

but high elevation populations were susceptible. About 6 

Figure 8.12—Modeled (a) current and (b) future (year 2060) climate space for Armillaria solidipes (Klopfenstein et al. 2009). 

Colors represent the probability of occurrence. Yellow = moderate, red = high.

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 341

percent of trees in this mixed provenance planting showed 

no infection, but 5 percent had almost complete defoliation. 

If moist conditions following bud break continue to occur 

at high elevation where natural selection for resistance has 

not occurred, recurrent needle disease outbreaks could stress 

trees and make lodgepole pine more susceptible to other 

factors (Hoff 1985).

Another example of a needle disease that may increase in 

the Northern Rockies region under climate change is Swiss 

needle cast (caused by Phaeocryptopus gaeumannii). This 

disease severely limits productivity of Douglas-fir west 

of the Cascade divide in Oregon and Washington, causing 

growth losses of up to 50 percent (Manter et al. 2005). 

Needle loss is very highly correlated with increasing winter 

temperatures and spring needle wetness. The disease, which 

is expected to become more severe in forests west of the 

Cascade crest in a warmer climate (Stone et al. 2008), has 

periods of local occurrence in northern Idaho (Navratil and 

Bella 1988) and Montana (Weir 1917). Milder winters and 

wetter springs that could increase the future distributions 

and severity of the disease might occur, but as yet, investigations and modeling have not been conducted to map and 

quantify potential effects.

Kliejunas (2011) performed a qualitative risk assessment of the effect of projected climate change on a number 

of forest diseases, several of which occur in the Northern 

Rockies. Dothistroma needle blight (caused by Dothistroma 

septosporum) provides a good example of potential effects 

of climate change. Kliejunas (2011) estimates that the risk 

potential is low if a warmer and drier climate occurs. A 

warmer and wetter climate could increase the risk potential 

to moderate. His assessment of the effect of climate change 

on dwarf mistletoes indicated a high risk potential regardless of precipitation levels because dwarf mistletoe survival 

and infection increases with temperature. His assessment 

of Armillaria root disease indicated a high to very high risk 

potential depending on moisture availability, with drier 

conditions increasing the potential.

Forest Pathogen Interactions

Direct effects of fire on pathogens are generally minimal. 

Fire directly and indirectly influences distribution, severity, 

and persistence of forest diseases; similarly, forest diseases 

influence fire behavior and severity. Diseases are generally 

host-specific, so removal of susceptible tree species by fire 

will usually reduce disease, whereas improving habitat for 

susceptible tree species will usually increase disease over 

time.

Forest pathogens are directly damaged by smoke and heat 

of fires. Smoke can inhibit dwarf mistletoe seed germination 

(Zimmerman and Laven 1987), and heat from fire can kill 

pathogens that cause root disease in the top 3 inches of soil 

(Filip and Yang-Erve 1997). Forest diseases are affected more 

by tree mortality from fire. Frequency and intensity of fire 

can affect persistence, as well as distribution and severity of 

certain diseases. High-intensity fires can completely remove a 

pathogen with its host, as with lodgepole pine-dwarf mistletoe 

(Kipfmueller and Baker 1998; Zimmerman et al. 1990), or 

remove species susceptible to root disease and prepare the 

site for regeneration of less susceptible seral species, such as 

pines and western larch (Hagle et al. 2000). Low-intensity 

fires often leave mosaics of pathogens along with their 

susceptible hosts, which can cause substantial increases of 

diseases such as dwarf mistletoe (Kipfmueller and Baker 

1998). However, low-intensity fires in some habitats maintain 

species tolerant of root disease such as western larch (Hagle 

et al. 2000).

Human-caused fire exclusion has led to an increase in root 

disease and dwarf mistletoe (Hagle et al. 2000; Rippy et al. 

2005), which can influence fire behavior and severity. Root 

disease creates pockets of mortality and scattered mortality; 

the resulting standing and down woody debris increases fuel 

loading, especially large fuels (Fields 2003). Increased litter accumulation and resinous witches’ brooms from dwarf 

mistletoe infections can provide ladder fuels that may cause a 

ground fire to move into the canopy (Geils et al. 2002).

Climate effects that increase frequency or intensity of 

fires may affect incidence and severity of dwarf mistletoes 

(Zimmerman and Laven 1985). Fire affects dwarf mistletoes 

by changing canopy structure and stand density (Alexander 

and Hawksworth 1975; Dowding 1929); eliminating lower 

branches, which may have the heaviest infections and 

mistletoe seed production; thinning stem density, which may 

reduce lateral spread; and causing mistletoe shoots to abscise. 

Loss of shoots eliminates some infections directly, but even if 

infections remain within the bark, loss of shoots prevents seed 

production for several years, slowing mistletoe intensification 

within stands. Trees heavily infested with mistletoe often 

retain low infected branches and are prone to torching in 

fire, which could increase the risk of crown fire (Conklin and 

Geils 2008). Alternatively, torching in individual trees could 

eliminate the most heavily infected sources of mistletoe seed 

that infect understory regeneration.

An increase in severe weather events or fires could 

increase occurrence of other diseases. For example, root and 

bole wounds could be used as “infection courts” for root 

disease, and such wounds from management, windfalls, and 

fire are major avenues of infection for true firs and western 

hemlock (Smith 1989) and lodgepole pine (Littke and Gara 

1986). Fire damage and other stresses can release root disease infections that have been walled off by host resistance 

responses (Hagle and Filip 2010). Relative importance of 

different root diseases could be altered under some climate 

change scenarios. Except as a sapling, western larch is considered resistant to Armillaria root disease due to its ability to 

generate multiple corky barriers at infection sites (Robinson 

and Morrison 2001). The response of this species to wounds 

and the thick bark that it generates also make it among the 

most resistant to fire damage, and a species more likely to 

persist and regenerate under increased fire frequency.

Illustrating interactions between bark beetles and disease, 

a study in lodgepole pine forests of central Oregon showed 

that altered stand structure following an MPB epidemic 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
342 USDA Forest Service RMRS-GTR-374. 2018

increases dwarf mistletoe in lodgepole pine stands, thereby 

reducing stand growth and productivity and slowing stand 

recovery (Agne et al. 2014). The influence of dwarf mistletoe 

on stand structure heterogeneity could increase landscape 

resistance and resilience to disturbances. Another example 

of complex interrelationships is the interaction between stem 

decay, bark beetles, and fire frequency in central Oregon 

lodgepole pine. After fire damaged the roots of lodgepole 

pines, stem decay fungi infected these damaged roots and 

over time caused extensive heartwood decay in the boles of 

these trees. Data show these decay-infected trees grew at a 

slower rate than uninfected trees and trees with stem decay 

were preferentially attacked by MPB years later (Littke and 

Gara 1986).

Nonnative Plants

Overview

Projecting how nonnative plants and climate change 

may interact to alter native plant communities, ecosystems, 

and the services they provide is challenging because of 

our limited ability to project how climate change will alter 

specific local abiotic conditions that define the fundamental 

niches of plants (Gurevitch et al. 2011; Thuiller et al. 

2008). We start with knowledge of structure and function 

of current ecosystems, and then apply first principles of 

ecology to explore how climate change might alter these 

systems, their susceptibility to invasion, and invasiveness 

of introduced plants from a general perspective. We do not 

project changes in individual plant species, but define the 

parameters that bound potential community change based on 

climate projections and discuss how community invasibility 

might be affected across that range of potential conditions.

Effects of Climate Change on 

Nonnative Species

Hundreds of nonnative species have been introduced into 

the Northern Rockies region (Rice n.d.). Not all of these 

species are abundant, but recent surveys showed that nonnative plants account for an average of 40 percent of species 

present (richness), and 25 percent of those nonnatives have 

significant effects on native grassland flora (Ortega and 

Pearson 2005; Pearson et al. in review). Invasive plant species represent a threat to ecosystem integrity because they 

compete with native species in many plant communities 

and can alter ecological processes. These negative impacts 

can reduce biological diversity, forage for wildlife, and 

recreation opportunities. Most nonnative invasive species 

are herbaceous species (graminoids and forbs), but some 

are shrub and tree species that commonly occur in riparian 

areas (e.g., Russian olive [Elaeagnus angustifolia], tamarisk 

[Tamarix ramosissima]).

Although extensive work has been done to understand 

the biology of some of the most common nonnatives, such 

information is far from complete. Few studies have explored 

how changes in temperature and moisture related to climate 

change may affect nonnative plant populations in the 

Northern Rockies region.

It has historically been assumed that climate change 

will favor nonnative plants over native species (Dukes and 

Mooney 1999; Thuiller et al. 2008; Vila et al. 2007; Walther 

et al. 2009), but this may be an overgeneralization (Bradley 

et al. 2009, 2010; Ortega et al. 2012). Numerous attributes 

associated with successful invaders suggest nonnative species could flourish under certain climate change scenarios. 

For example, many nonnative plants are fast-growing 

early-seral species (ruderals) that tend to respond favorably 

to increased availability of resources, including temperature, 

water, sunlight, and CO2 (Milchunas and Lauenroth 1995; 

Smith et al. 2000; Walther et al. 2009). Extensive work 

shows that nonnative species respond favorably to disturbance (Zouhar et al. 2008), which can increase resource 

availability (Davis et al. 2000). Nonnative species may also 

exploit the disturbances associated with postfire conditions 

better than many native species (Zouhar et al. 2008), despite 

the adaptations of native plants to fire. In bunchgrass communities, many nonnative plants recruit more strongly than 

do native species when native vegetation is disturbed, even 

under equal propagule availability (Maron et al. 2012). 

Successful invaders also commonly have strong dispersal 

strategies and shorter generation times, both of which can 

allow them to migrate more quickly than slow-growing and 

slowly dispersed species (Clements and Ditommaso 2011). 

Greater plasticity of successful invaders could also favor 

their survival in place and ability to expand their populations (Clements and Ditommaso 2011). Collectively, these 

attributes suggest that many nonnative species would benefit 

if climate change results in increased disturbance.

Few studies have manipulated CO2, moisture, or temperature to quantify the effects of climate change on nonnative 

versus native plants in the Northern Rockies region. Of 

the work that does exist, most has targeted grassland and 

sagebrush communities, presumably because these are 

among the most susceptible to invasion (Forcella 1992; see 

also Chapter 7). Experimentally increasing temperatures in 

a Colorado meadow system resulted in increases in native 

upland shrubs, with big sagebrush (Artemisia tridentata) 

increasing in drier conditions and shrubby cinquefoil 

(Dasiphora fruticosa) in wetter conditions (Harte and Shaw 

1995). These different responses indicate the importance of 

background moisture in driving species-specific responses 

to elevated temperatures.

Recent experimental work in western Montana showed 

that reduced precipitation can significantly impact spotted 

knapweed (Centaurea melitensis), whereas native bluebunch wheatgrass (Pseudoroegneria spicata) populations 

were unaffected by the same drought stress (Ortega et 

al. 2012; Pearson et al., unpublished data). This result is 

consistent with historical observations of spotted knapweed declines following drought conditions (Pearson and 

Fletcher 2008). In Wyoming sagebrush-steppe systems, 

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 343

bluebunch wheatgrass outperformed both cheatgrass and 

medusahead (Taeniatherum caput-medusae) in dry years, 

but the opposite was true in wet years (Mangla et al. 2011). 

Community-level studies in other grasslands have shown 

that drought periods can shift vegetation away from annual 

grasses and forbs and toward drought-tolerant native perennial grasses (Tilman and El Haddi 1992). Hence, heating 

and drying could favor drought-tolerant native species in 

dry grassland and sagebrush systems and reduce their susceptibility to invasion by nonnative species (see Chapter 7). 

However, these conditions might increase susceptibility of 

native vegetation to invasive species in wetter locations.

Xeric Grasslands and Shrublands

Of the many dominant cover types that occur in the 

Northern Rockies region, the most vulnerable to weed invasion are typically those on warm, dry (xeric) sites, although 

riparian and wetland sites can be invaded by several invasive plant species. The most susceptible plant communities 

tend to have low vegetation cover, high bare ground, and 

unproductive soils; various nonnative plant species exploit 

these more open sites. However, disturbances resulting from 

fire or vegetation management can provide opportunities for 

invasion in most kinds of dominant vegetation. Hundreds of 

nonnative plant species occur in the Northern Rockies, the 

most serious of which are described in table 8.8.

Xeric grasslands and shrublands are highly vulnerable to 

establishment of nonnative species (see Chapter 7). Many of 

the native plants in Northern Rockies grasslands are perennials that tolerate environmental variability over long time 

scales in contrast with the life history strategies of weedy 

invasive species (Grime 1977; MacArthur and Wilson 

1967). Whether native or nonnative species benefit, or more 

specifically, which native or nonnative species benefit, will 

probably depend on the specific ways in which climate 

change plays out.

If temperature increases but precipitation does not, this 

will likely reduce resource availability and increase stress, 

potentially favoring nonnative species. Projections of the 

effects of climate change need to consider how nonnative 

plants respond, as well as how recipient communities and 

their invasibility may change. Many successful nonnative 

species flower later and have different phenologies from 

native species, allowing nonnative species to potentially 

exploit an empty niche (Pearson et al. 2012). Therefore, 

nonnative species may increase if this niche expands with 

climate change, or decline if the niche is disrupted.

Invasive species primarily spread into disturbed areas 

with sufficient bare ground and sunlight for germination 

and establishment, although some species such as spotted 

knapweed, houndstongue (Cynoglossum officinale), yellow 

sweet clover (Melilotus officinalis), and yellow toadflax 

(Linaria vulgaris) can readily establish in undisturbed 

plant communities. Nonforested landscapes (e.g., shrublands, grasslands) have been invaded in many areas of the 

Northern Rockies region (see Chapter 7). As fires and other 

disturbances increase in intensity and frequency, invasive 

species can occupy and potentially dominate native plant 

communities that were previously resistant to invasion, 

although numerous factors such as fire resistance of native 

species, propagule availability, and variation in burn severity can affect establishment (Zouhar et al. 2008). Native and 

domestic livestock grazing and browsing of native species 

can reduce plant vigor and open up sites for establishment 

of invasive species. Silvicultural prescriptions that decrease 

canopy cover also increase the likelihood that invasive species may establish and increase in both cover and density, 

Table 8.8—Prominent nonnative species in the Northern Rockies and their primary habitats. 

Species Habitat

Cheatgrass (Bromus tectorum) Xeric shrublands and grasslands

Spotted knapweed (Centaurea maculosa) Xeric shrublands and grasslands, dry forest openings

Rush skeletonweed (Chondrilla juncea) Xeric shrublands and grasslands

Canada thistle (Cirsium arvense) Wetland/riparian areas, disturbed sites in moist grasslands

Houndstongue (Cynoglossum officinale) Highly disturbed mesic and xeric grasslands, roadsides

Leafy spurge (Euphorbia esula) Riparian areas, mesic and xeric grasslands

Orange hawkweed (Hieracium aurantiacum) Forest openings, moist meadows, roadsides

Yellow hawkweed complex (Hieracium spp.) Forest openings, roadsides

St. Johnswort (Hypericum perforatum) Xeric grasslands and shrublands

Dalmatian toadflax (Linaria dalmatica) Xeric grasslands and shrublands

Yellow toadflax (Linaria vulgaris) Mesic to xeric grasslands and shrublands, burned areas

Sulfur cinquefoil (Potentilla recta) Xeric grasslands and shrublands

Common tansy (Tanacetum vulgare) Riparian areas

Chapter 8: Effects of Climate Change on Ecological Disturbance in the Northern Rockies Region
344 USDA Forest Service RMRS-GTR-374. 2018

although subsequent succession may suppress those species 

as canopy closure returns.

Climate change is likely to result in a range of responses 

among invasive species, due to differences in their ecological amplitude and life history strategies (table 8.9). 

Bioclimatic envelope modeling indicates that climate 

change could result in both range expansion and contraction for five widespread and dominant invasive plants in 

the western United States. Yellow starthistle (Centaurea 

solstitialis) and tamarisk are likely to expand, whereas leafy 

spurge (Euphorbia esula) is likely to contract; cheatgrass 

and spotted knapweed are likely to shift in range, leading to 

both expansion and contraction (Bradley 2009; Bradley et 

al. 2009). Invasive species are generally inherently adaptable and capable of relatively rapid genetic change, which 

can enhance their ability to invade new areas in response to 

ecosystem modifications (Clements and Ditomaso 2011), 

including short-term disturbance (fire) or long-term stressors 

(e.g., prolonged drought, increased temperatures, chronic 

improper grazing). Increased concentrations of CO2 in the 

atmosphere have been shown to increase the growth of weed 

species, which could have an influence on their invasiveness 

(Ziska 2003).

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component

Direction 

of change

Main driver(s) 

of change

Likelihood 

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Area infested Variable by species, 

from low to high

Altered temperature and precipitation 

patterns; increased atmospheric CO2; 

altered fire regimes

High

Species response to 

habitat disturbance

High Increased fire frequency and severity, 

which can increase the amount of habitat 

vulnerable to nonnative invasion

High

Altered fire regimes High Increased fire frequency in areas with firetolerant and flammable invasive species 

(e.g., cheatgrass-fire cycle)

High

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How Climate Affects Wildlife

Temperature and moisture affect organisms through their 

operational environment and the thin boundary layer immediately above their tissues, and these effects are measured 

at short time scales. When a human (a mammal) wearing 

a dark insulative layer walks outdoors on a cold but sunny 

day, he or she feels warm because energy from the sun is 

interacting with the dark clothing, creating a warm boundary 

layer to which his or her body reacts. Conditions beyond 

that thin boundary layer are physiologically irrelevant. Walk 

into the shade, and suddenly one is cold because the warm 

boundary layer has been replaced with one at the ambient 

temperature of the air. This example demonstrates many 

factors to consider when evaluating the degree to which a 

change in climate will affect an organism. Climate is defined 

as the long-term average of temperature, precipitation, and 

wind velocity. “Long term,” when applied to climate, is a 

relative term and can refer to periods of weeks to centuries. 

In the context of climate models, results are generally reported as averages across 30-year intervals, which for many 

animal species represent multiple generations. Our ability to 

infer the biological effects of projected long-term changes 

in temperature and precipitation relies both on our ability 

to directly relate these multiyear averages to biological 

responses, and the trophic distance between climate-induced 

ecological change and its effects on specific biological 

relationships.

As just noted, a human’s response to change in radiant energy is fast, measured in seconds to minutes, so 

its relation to 30-year average temperature is obscure. 

Climate changes the frequency of weather events, which 

in turn change the frequency of nearly instantaneous shifts 

in boundary layer conditions around one’s body. In aggregate, these changes in frequency lead to conditions that 

an individual either can navigate and tolerate—or cannot. 

This is further complicated for endotherms (warm-blooded 

animals), which maintain a constant body temperature. Cold 

or excessive heat affects endotherms by requiring them 

to burn more calories to maintain the required core temperature. Thus, endotherms can function in a wide variety 

of environmental conditions if they have enough food to 

supply the necessary energy. Fish, reptiles, and amphibians 

are ectotherms (cold-blooded organisms), which react to the 

cold not by feeling cold and metabolizing energy to maintain core temperature, but by having their metabolism slow 

until they are torpid.

Many of the species described here occupy terrestrial 

habitats. Terrestrial organisms can manipulate their operational environment in a myriad of ways, choosing to stand in 

the sun or shade, moving uphill or down, changing aspect, 

or seeking cooler or warmer environments by digging into 

a burrow in the ground or under the snow. Endothermic 

animals can change the thickness of the boundary layer by 

modifying their hair or feathers, both seasonally and on a 

short-term basis, thus responding to variable thermal conditions while minimizing energy expenditures. The ability of 

terrestrial organisms to manipulate their operational environment contrasts with aquatic organisms, which have a harder 

time avoiding adverse temperatures because water is an 

excellent conductor of heat. In addition, aquatic ectotherms 

have no way to avoid overheating when water temperatures 

rise, so it is more straightforward to evaluate the effects of 

climate change for fish with known warm-water limits than it 

is for terrestrial endotherms (see Chapter 5).

Terrestrial endotherms are more likely to experience effects associated with changes in precipitation amounts and 

types than effects associated with changes in temperature. 

These species have less flexibility in dealing with changes 

in precipitation patterns than with changes in temperature 

Chapter 9: Climate Change and Wildlife in 

the Northern Rockies Region

Kevin S. McKelvey and Polly C. Buotte 

Figure 9.1—Visual summary of workshop discussions on 

the influence of climate on wildlife populations in the 

Northern Rockies Adaptation Partnership. Pathways 

of climate influence (black) interact with population 

characteristics (blue) to affect the future population status 

(red). A given pathway affects multiple species, and 

multiple pathways affect a given species.
354 USDA Forest Service RMRS-GTR-374. 2018

because water produces physical features that serve as habitat for which they are specifically adapted. In the Northern 

Rockies region, and in other areas with cold winters, snow 

provides physical habitat for which a number of organisms 

have specific adaptations. An obvious adaptation is seasonal 

color change in pelage: being white in a snowy landscape 

enhances the likelihood of escaping detection if the animal 

is prey, and approaching prey if the animal is a predator. 

Therefore, white pelage in winter confers specific fitness 

advantages if pelage change is properly timed to coincide 

with snow cover. But it is a disadvantage if mistimed (see 

discussion of snowshoe hare [Lepus americanus] later in 

this chapter) (fig. 9.2). Specific morphological features such 

as oversized feet, long legs, and light bone structures also 

provide benefits in snow-covered landscapes but may be 

disadvantageous in environments without snow.

Deep snow provides a relatively warm, stable environment at the interface between snow and soil; soils in areas 

characterized by deep snow generally remain above freezing 

throughout the winter (Edwards et al. 2007), and the subnivean environment (beneath the snow surface) is used by 

many organisms to den or feed. For organisms that depend 

on a stable subnivean environment or that have specific 

phenological adaptations to snow, reduced snowpack caused 

by a shift in precipitation from snow to rain represents a 

loss of critical habitat (see later discussion of American pika 

[Ochotona princeps]). Similarly, water bodies are the physical habitats for a wide variety of animals, providing sources 

of prey, temperature control, and safety from predation. In 

addition, open or flowing water can provide important microclimates. For example, pikas can be found in what appear 

to be hot, dry environments if water flow beneath the talus 

produces cool microsites (Millar and Westfall 2010a).

Physical features associated with snow and water integrate across longer time periods and are therefore closely 

associated with projected climate. For example, depth of 

snowpack integrates seasonal moisture and temperature. 

Seeps, springs, bogs, and persistent streams dependent on 

continuous sources of groundwater can integrate longer climatic periods. In some areas, water features are dependent 

on glaciers, which integrate seasonal weather and long-term 

climate. Therefore, areas with these features and the species 

that depend on them are vulnerable to climate change, reacting at time scales reasonably consistent with the temporal 

projections of global climate models (GCM) and providing 

opportunities to project effects on habitats and species.

As noted earlier, terrestrial endotherms have many options for controlling both their operational environments and 

the physiological effects of these environments. Terrestrial 

plants are stationary ectotherms and, lacking the behavioral 

and physiological plasticity of endothermic animals, are 

more directly affected by climate changes (see Chapter 6). 

Therefore, climate effects on wildlife will frequently occur 

due to changes in plant assemblages that constitute wildlife 

habitat. For predators, these effects may be either direct 

(e.g., changes in the number and locations of vegetation 

boundaries used by predators) or indirect through changes 

in prey densities or prey availability to predators. Climateinduced changes in trophic structures are expected to be 

common, complex, and interactive, but are at least one step 

removed from climate (e.g., Post et al. 1999).

The effects of habitat changes on a specific animal are 

difficult to project and require specific understanding of the 

functional roles that ecological attributes play in the life 

history of the animal, and the consequences associated with 

alternative life history strategies. These types of data are 

often lacking, and although current behaviors can be studied, they may not be informative relative to climate change 

effects, and responses may be novel and unanticipated. For 

example, polar bears (Ursus maritimus) are historically 

Figure 9.2—Canada lynx (a) have snow-specific adaptations (oversized feet, long legs, and a thin, light skeleton), and snowshoe 

hares (b) dominate their diets. Snowshoe hares undergo seasonal pelage changes from brown to white, and the effectiveness 

of this strategy depends on synchrony with snow cover. A mismatch between the hare’s fur color and its environment would 

make it more vulnerable to predation by lynx (photo (a): U.S. Fish and Wildlife Service; (b) photo: L. Scott Mills, used with 

permission).

A B

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 355

adapted to pack-ice hunting for seals, but with recent reductions in pack ice, they have in some areas shifted to feeding 

on the eggs of snow geese (Chen caerulescens) (Rockwell 

and Gormezano 2009), whose populations have erupted 

because of their ability to feed in agricultural fields (Fox et 

al. 2005).

In addition to changes in vegetation and prey, trophic 

effects include the presence and abundance of disease and 

parasitic organisms. For example, for greater sage-grouse 

(Centrocercus urophasianus), the potential spread of 

West Nile virus (Flavivirus spp.) associated with climate 

change may increase stress in grouse populations (Schrag 

et al. 2011), but the effect is difficult to project. For many 

organisms, current ranges are often strongly limited by human activities. For example, greater sage-grouse range is 

limited by conversion of native sagebrush (Artemisia spp.) 

habitat to agricultural uses (Connelly et al. 2004; Miller and 

Eddleman 2001).

Last, climate change is likely to alter the nature and location of human activities that affect wildlife. In the western 

United States, changes in water availability and the amounts 

required for irrigation can be expected to have profound 

effects on human activity and settlement patterns (Barnett et 

al. 2005). In addition, societal effects associated with local 

changes will occur within the context of societal changes 

across much larger spatial domains. Changes in technology, 

standards of living, infrastructure, laws, and the relative impacts of climate changes in other areas, will all affect local 

human activities.

In summary, the ways that climate change affects endothermic terrestrial species are likely to be complex and 

difficult to project. In addition to the uncertainty of future 

climate itself (see Chapter 3), effects on most species will 

be indirect through proxies such as ecological disturbance, 

habitat structure, prey availability, disease dynamics, and 

shifts in human activities.

The Importance of Community 

in Defining Habitat

Our understanding of wildlife ecology, particularly at 

broad spatial scales, is generally limited to the correlation of 

occurrence patterns to landscape features rather than direct 

studies of those factors that limit species distributions. In 

some cases, patterns of occurrence are clear, consistent, 

and highly correlated with climate (see later discussion on 

wolverine [Gulo gulo]), but the causal relationships remain 

obscure. For instance, many passerine birds nest only in 

specific habitats; an example is Brewer’s sparrow (Spizella 

breweri) (see later discussion), which is obligate to sagebrush. Although the pattern is clear and invariant, the nature 

of the obligate links to sagebrush is unknown. Species such 

as ruffed grouse (Bonasa umbellus) (see later discussion) 

clearly have northern distributions, but the factors that 

define the southern limits of their current distributions are 

not well understood (Lowe et al. 2010).

This lack of causal understanding may be unimportant 

for current management of these species because management takes place only in areas where the species currently 

occurs or where it occurred in the recent historical past. 

Based on observed patterns of use and distribution, enough 

information exists to identify and manage current habitat. 

However, it cannot be assumed that measured correlations 

will persist in an altered climate. We typically characterize 

habitat elements within the context of assemblages of mostly unmeasured plants and animals. For example, assume that 

an organism’s occurrence is strongly correlated with mature 

Douglas-fir (Pseudotsuga menziesii) forests. These forests 

contain other tree and understory species, animal communities, and successional trajectories (e.g., habitat types; 

Daubenmire [1952]). However, Douglas-fir projected onto a 

future landscape may be associated with different plant and 

animal communities. Due to the correlational nature of most 

of our habitat knowledge, it is difficult to know which of 

these community members are critical to habitat quality for 

a target species and thus the habitat quality of novel species 

assemblages.

In addition, factors identified as important are restricted 

to those that currently limit behavior. Therefore, in correlation-based habitat relationships, changes in non-limiting 

but essential factors will not produce strong correlations 

with behaviors. For example, distance to water may be a 

strong habitat correlate in desert environments but may not 

be correlated with habitat quality in a rainforest. Water may 

be no less important in the rainforest, but it is currently not 

limiting. As climate change alters biophysical attributes 

of landscapes, limiting factors and definitions of what 

constitutes habitat may change. Water availability might 

become the most critical habitat attribute in a previously wet 

environment that has become dry. For the most part, these 

important but latent habitat attributes will remain unknown 

until exposed by changes in climate.

In addition to potentially changing vegetation communities and limiting factors, the effects of climate on future 

habitats are further complicated by altered disturbance 

regimes. Regeneration, growth, and disturbance patterns collectively create landscapes that provide habitats. 

Changing disturbance dynamics (see Chapter 8) alter the 

characteristics of landscape mosaics and fundamentally 

alter habitats. As climate change causes shifts in plant and 

animal distributions, a temporal mismatch between decrease 

of current habitat and increase of new habitat may occur, 

a mismatch that will be exacerbated by increased levels 

of disturbance. Wildfire can destroy current habitat in a 

day, but generation of new habitat may require centuries, 

depending on the time necessary to create critical elements 

through regeneration, growth, and succession. The fisher 

provides an example of these uncertainties. In Idaho and 

Montana, fishers are currently limited to mature forests in 

the Inland Maritime climatic zone. However, GCMs indicate 

that this zone will move to the east, and mature forest may 

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
356 USDA Forest Service RMRS-GTR-374. 2018

take a century or more to grow in these new locations, creating uncertainty about the future range of fisher (see later 

discussion).

Given the uncertainty associated with determining likely 

trajectories of species and their habitats under climate 

change, assessments of general vulnerability and projected 

changes can best be viewed as hypotheses to be tested. 

Therefore, it is desirable to develop proactive management 

strategies that maintain valued species and landscape attributes, including objectives such as creating resilience 

to disturbance. Prioritizing which things are measured can 

improve the connection between environmental change and 

management. A monitoring program designed to test specific hypotheses associated with specific organisms (Nichols 

and Williams 2006) can improve our understanding of relationships between climate change and landscapes, providing 

data that inform science-based management.

Evaluating Sensitivity of Species 

to Climate Change

Evaluating the potential effects of climate change on 

animal species begins with determining which species are of 

interest, collecting biological information about them, and 

paying special attention to biological traits that might lead to 

changes in distribution and abundance in a warmer climate 

(e.g., Glick et al. 2011). Some species have received significant attention, and this interest has generated peer-reviewed 

articles that formally analyze the effects of climate change, 

although this is relatively uncommon.

Foden et al. (2013) identify three dimensions associated 

with climate change vulnerability—sensitivity, exposure, 

and adaptive capacity—and apply a framework based on 

assessing these attributes to nearly 17,000 species. Other 

expert systems have been developed to evaluate the relative degree of climate sensitivity and vulnerability for 

various species including the Climate Sensitivity Database 

(Lawler and Case 2010) and NatureServe Climate Change 

Vulnerability Index (NatureServe n.d.). These tools do not 

seek to understand specific responses of animals to climate, 

but rather to identify species that are likely to be vulnerable 

based on current habitat associations, life history traits, and 

distributions (Foden et al. 2013). Bagne et al. (2011) formalized this process in the System for Assessing Vulnerability 

of Species (SAVS). In SAVS, species are assessed based 

on a large number of traits associated with habitat (seven 

traits), physiology (six traits), phenology (four traits), and 

biotic interactions (five traits). For each of these 22 traits, a 

score of ‒1, 0, or 1 is assigned; positive scores indicate vulnerability, and negative scores indicate resilience. The raw 

scores are multiplied by correction factors associated with 

the number of traits in a category and possible scores across 

traits to achieve a standardized score between ‒20 and 20 

that indicates the relative vulnerability of the species.

Formalizing traits that can lead to vulnerability provides 

a framework for collecting biological data associated with 

a species and for considering the effects of climate change. 

However, existing expert systems cannot be used to infer 

that sensitivities for disparate topics such as habitat and 

phenology are proportionally important or that estimated 

vulnerability has quantitative meaning (Bagne et al. 2011; 

Case et al. 2015). Even if these issues were considered 

unimportant, accurately identifying vulnerability for most 

of the species evaluated here would not be possible given 

current biological understanding. Because data on climatespecies relationships are so sparse, this assessment focuses 

primarily on evaluation of each trait as it relates to the biology of animal species.

Following are assessments for animal species identified 

as high priority by Forest Service, U.S. Department of 

Agriculture (USFS) Northern Region resource specialists, 

and for additional species identified by participants in five 

workshops convened by the Northern Rockies Adaptation 

Partnership (see Chapter 1). Species were not necessarily 

chosen based on their perceived level of vulnerability. In 

many cases, species are associated with specific habitats 

that were considered vulnerable; for example, some species 

are associated with sagebrush communities, others with 

snow depth and cover, and others with dry forests that have 

large trees. These assessment summaries contain projections of climate change effects based on interpretation of 

the pertinent literature. Level of detail differs considerably 

among species and is mostly driven by the degree to which 

the species have been evaluated in the context of climate 

change. Species are listed in alphabetical order within each 

taxonomic class.

Mammals

American Beaver

American beavers (Castor canadensis), like their 

European counterpart (C. fiber), tend to spend most of the 

winter in their lodges or swimming to retrieve food, so climate may be more influential during spring through autumn 

than during winter (Jarema et al. 2009). However, body 

weights of juvenile European beavers were lighter when 

winters were colder (Campbell et al. 2013). The cost of thermodynamic regulation may be greater for juveniles because 

they have higher surface area-to-volume ratios than adults 

(on whom winter temperature had no effect) (Campbell et 

al. 2013).

In Quebec, beaver density was highest in areas with the 

highest maximum spring and summer temperatures (Jarema 

et al. 2009). Conversely, European beavers in Norway 

achieved heavier body weights when spring temperatures 

were lower, and the rate of vegetation green-up was slower 

(Campbell et al. 2013). This apparent contradiction may 

have been caused by the timing and measurement of climate 

and response variables. Although beavers create and require 

ponds, survival and body weight in European beavers have 

been linked to lower, and more consistent, precipitation 

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 357

from April through September (Campbell et al. 2012, 2013). 

Higher water levels during high precipitation years were 

thought to lead to decreased riparian plant growth caused by 

waterlogging (Campbell et al. 2012).

Climate can indirectly influence beavers through effects on vegetation. Climate change and climate-driven 

changes in streamflow are likely to reduce the abundance of 

dominant early-successional tree species in riparian habitats 

(Perry et al. 2012), reducing food and building materials for 

beaver. Beavers can be used as a management tool to buffer riparian systems from drought (Lawler 2009) (fig. 9.3). 

Beaver ponds increase the amount of open water (Hood and 

Bayley 2008), and beaver management can be used as a surrogate for amphibian conservation (Stevens et al. 2007).

American Pika

The American pika (Ochotona princeps) is a small 

(5–8 ounces) lagomorph that often inhabits rocky alpine 

areas in western North America (Smith and Weston 1990) 

(fig. 9.4). The species has been extensively studied in the 

Great Basin, where pika habitat typically occurs as small 

islands near mountaintops. Relatively little study of pikas 

had occurred in the Northern Rockies until recently, with 

the exception of research on occupancy and abundance in 

relation to microclimate, topography, and vegetation in the 

Bighorn Mountains and Wind River Range (Wyoming) 

(Yandow 2013). Studies are in process in the BridgerTeton National Forest and Greater Yellowstone Area (Erik 

Beever, U.S. Geological Survey, Northern Rocky Mountain 

Science Center, Bozeman, MT, August 2014, personal 

communication).

Research suggests that pikas depend on moist, cool summer conditions and winter snow (Beever et al. 2011), and on 

low water-balance stress and green vegetation (Beever et al. 

2013). Across paleontological time scales (Grayson 2005) 

and during the 20th century, pikas across the Great Basin 

have reacted to increasing temperature by moving upslope 

or becoming locally extirpated when the climate becomes 

hot and dry (Beever et al. 2011). Results from field research 

from 2012 through 2014 in the Great Basin indicate that local extirpations and retractions are continuing (Erik Beever, 

U.S. Geological Survey, Northern Rocky Mountain Science 

Center, Bozeman, MT, August 2014, personal communication). Local changes in pika distribution have also been 

recorded in Utah, the southern Sierra Nevada, and southern 

and central Cascade Range (Beever et al. 2011 and references therein).

In the Great Basin, pika extirpation (1994–2008) occurred in microsites that were generally hotter in summer 

(more frequent acute heat, and hotter average temperature 

across the whole summer) and were more frequently very 

cold in winter than in locations where pikas persisted. In 

the latter case, warming reduced insulating snow, causing 

near-ground temperatures to decrease (Beever et al. 2010). 

Furthermore, density of pikas in surveys from 2003 through 

2008 was best predicted by maximum snow water equivalent and growing-season precipitation (Beever et al. 2013). 

Some extirpations have occurred at sites with low annual 

precipitation (Beever et al. 2011, 2013), reinforcing study 

results in the southern Rocky Mountains (mostly Colorado), 

where surveys indicated that 4 pika extirpations (among 69 

total sites with historical records) occurred at the driest sites 

(Erb et al. 2011).

Winter snowpack not only insulates pikas during cold 

periods, but also provides water during the summer, when 

plant senescence at drier sites occurs earlier in the year, 

eliminating available metabolic water for pikas. Surveys, 

mostly in the Sierra Nevada, found that pika extirpations 

Figure 9.3—Maintenance and 

restoration of American beaver 

populations are adaptation tactics 

for maintaining water on the 

landscape. Although beavers are 

not particularly climate sensitive 

themselves, the structures beavers 

create and their effects on aquatic 

habitats and floodplains may help 

to ameliorate the effects of climatic 

change on cold-water fish species 

and other aquatic organisms (photo: 

E. Himmel, National Park Service).

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
358 USDA Forest Service RMRS-GTR-374. 2018

were associated with sites with higher maximum temperatures and lower annual precipitation (Millar and 

Westfall 2010b). Chronic stresses (average temperature 

during summer, maximum snowpack, and growing-season 

precipitation), acute temperature stresses (hot and cold), 

and vegetation productivity apparently contributed to pika 

declines in the Great Basin (Beever et al. 2010, 2011, 2013).

Individual mountain ranges are thought to act as discrete 

areas without any pika migration between adjacent ranges 

across valley bottoms (Castillo et al. 2014), although disjunct metapopulations of pikas separated by short distances 

may exist. In a study of pika populations in ore dumps separated by tens to hundreds of yards, individual populations 

that were extirpated were recolonized, and abundance across 

all ore piles remained constant (Smith 1980). This process 

apparently occurs only at very short distances because 

habitats isolated by more than 1,150 feet were generally 

unoccupied. Connectivity of pika populations apparently depends on context, with lower connectivity between sites that 

occur in hotter, drier landscapes (Castillo et al. 2014; Henry 

et al. 2012). Thus, recolonization may occur at distances 

less than 0.5 mile and in areas where between-population 

dispersal occurs within cool, moist landscapes, whereas 

recolonization at longer distances is rare. In the Great Basin, 

once pikas have been extirpated from a site, they have never 

been detected in subsequent surveys across 21 years of contemporary research (Beever et al. 2011).

At the broadest spatial scales, there is genetic evidence 

for historical isolation; pikas across the Intermountain West 

separate into five distinct groups (Galbreath et al. 2010). 

At smaller scales, inbreeding and high levels of genetic 

structure exist between high and low elevation populations 

in British Columbia, even when the populations are geographically proximal. Castillo et al. (2014) found that gene 

flow is restricted primarily by topographic relief, water, and 

west-facing aspects, suggesting that physical restrictions 

related to small body size and mode of locomotion, as well 

as exposure to relatively high temperatures, limited pika 

dispersal.

Studies in the Sierra Nevada (Millar and Westfall 

2010a,b) and southern Rocky Mountains (Erb et al. 2011), at 

sites in which pikas were common and not generally subject 

to extirpation across most of the landscape, indicated that 

physiological limits for this species had not been reached. 

This will probably be the case for most pika populations 

in the Northern Rockies region in the near term. Although 

hot, dry climate may limit pika distributions, local moisture 

sources, rock-ice features, aspect, and the physical structure 

of talus fields may climatically buffer pikas from macroclimatic stresses (Millar and Westfall 2010a). Existence 

of pikas at Lava Beds National Monument, Craters of 

the Moon National Monument, and the Columbia River 

Gorge—all of which have warm, dry climates—underscores 

the importance of microclimate for species vulnerability 

assessments, and indicates that microclimate and macroclimate are decoupled in some locations (Rodhouse et al. 

2010; Simpson 2009; Varner and Dearing 2014).

Because pikas are sensitive to high temperature, we expect that pika populations will respond to climate change in 

the Northern Rockies region. However, site-specific factors 

contribute to highly variable microclimates, so response to 

climate change will vary considerably over space and time. 

A large amount of data has been collected on this species 

over the past decade, and it should be possible to develop 

more-accurate projections of population response as monitoring data continue to accrue.

Canada Lynx

The Canada lynx (Lynx canadensis) is a mid-sized cat 

with several specific adaptations that allow it to travel 

across soft snow. The most obvious adaptation is oversized 

feet: foot loading is 0.5 times that of the similar sized 

bobcat (L. rufus) (Buskirk et al. 2000). Canada lynx prey 

nearly obligately on snowshoe hares (fig. 9.2). Not only do 

snowshoe hares constitute 33 to 100 percent of lynx diet 

(Mowat et al. 2000), but a low proportion of hares in the 

diet indicates scarcity of hares, not diet plasticity (Mowat et 

al. 2000). Studies of lynx winter diet in the Clearwater River 

watershed (western Montana) found 94 to 99 percent of the 

diet consisted of snowshoe hares (Squires and Ruggiero 

2007). Snowshoe hares are also specially adapted to snowy 

environments. When compared to similar sized leporids, 

they have oversized feet. They also exhibit seasonal pelage 

change from brown to white. Because lynx and hares have a 

close association and have specialized adaptations to allow 

survival in snowy environments, climate relationships for 

both species are explored in this section.

The Canada lynx is found exclusively in North America, 

its distribution extending across the interior of Canada and 

Alaska and northward into tundra vegetation. In the conterminous United States, both current and likely historical 

Figure 9.4—The American pika is a small lagomorph that 

collects grass and herbs throughout the summer as winter 

food and remains active throughout the winter. It depends 

on the relatively warm subnivean environment associated 

with deep winter snowpack (photo: Will Thomson, U.S. 

Geological Survey).

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 359

populations are located in the extreme northern portions 

of this region: Maine, historically New York and New 

Hampshire, Minnesota north of Lake Superior, western 

Montana, and northern Washington (McKelvey et al. 2000). 

A tiny population existed and may still exist in the Greater 

Yellowstone Area. Periodically, in the years immediately 

after major population eruptions in the north, lynx distributions expand; lynx were found ephemerally in North 

Dakota, and populations temporarily increased in Montana 

(McKelvey et al. 2000). Bobcats and lynx were not well differentiated in the fur market (Novak et al. 1987)—with large 

bobcats often recorded as “lynx”—so trapping records are 

typically untrustworthy (McKelvey et al. 2000). Recently, 

a population was translocated to Colorado, and appears 

to be persisting; after initial high mortality rates, annual 

survival has exceeded 90 percent (Devineau et al. 2010). 

However, the historical evidence for lynx in Colorado is 

weak, with most of the verified records occurring in years 

consistent with immigration from the north (McKelvey et 

al. 2000). Hare densities in Colorado are generally less than 

the threshold of 0.5 hare per acre (Ivan et al. 2014) thought 

to be the minimum hare density associated with stable lynx 

populations (Mowat et al. 2000).

When evaluating the potential distribution of lynx, it is 

important to note that large populations of lynx are located 

in the interior of the continent. Lynx are common in Alberta 

and Saskatchewan, where more than 20,000 were trapped 

per year in recent eruptions (Novak et al. 1987), but they 

are and were rare along both the Atlantic and Pacific coasts. 

Lynx are more common in areas with a northern continental 

climate, probably because soft powdery snow is more common there.

Maintaining population connectivity is central to lynx 

conservation. However, maintaining connectivity may 

become increasingly difficult as southern populations of 

boreal species become more isolated with climate change 

(van Oort et al. 2011). This is of particular concern because 

disturbance processes that include wildfire, insects, and disease make some boreal forests vulnerable to climate change 

(Agee 2000; Carroll et al. 2004; Fishlin et al. 2007; Fleming 

et al. 2002; Intergovernmental Panel on Climate Change 

[IPCC] 2007a,b; Logan et al. 2003).

In the Northern Rockies region, lynx exist in only a 

few areas: the Clearwater River watershed, Bob Marshall 

Wilderness, and the northwestern corner of Montana. A few 

lynx were known to inhabit the Greater Yellowstone Area 

in 2000 (Squires and Laurion 2000), but their current status 

is unknown. Dens are located in boulder fields and sprucefir forests with high horizontal cover and abundant coarse 

woody debris. Eighty percent of dens are in mature forest 

and 13 percent in mid-seral regenerating stands (Squires et 

al. 2008). For winter foraging, lynx preferentially forage in 

mature, multilayer spruce-fir forests composed of larger diameter trees with high horizontal cover, abundant snowshoe 

hares, and deep snow (Squires et al. 2010). During summer, 

lynx occupy young forests with high horizontal cover, 

abundant total shrubs, abundant small diameter trees, and 

dense spruce-fir saplings (Squires et al. 2010). Lynx select 

home ranges with vegetative conditions consistent with 

those identified for foraging and denning, primarily at midelevations (Squires et al. 2013). Assuming that preferences 

for movement between home ranges are similar to those 

associated with moving within the home range, dispersal 

pathways consist of areas with similar properties to those 

used for foraging (Squires et al. 2013).

The range of snowshoe hare (Hall and Kelson 1959) is 

more extensive than that of lynx, extending into the midSierra Nevada and areas such as the Olympic Peninsula, 

where there are no records of lynx occurrence (McKelvey 

et al. 2000). The more extensive hare distribution, which 

includes areas with limited snow (e.g., the Pacific coast), 

is probably caused by greater genetic differentiation for 

snowshoe hares than for lynx. Across the continent, lynx exist in a single, largely panmictic (random mating) population 

(Schwartz et al. 2004), whereas hares are subdivided into six 

subspecies (Wilson and Reeder 2005).

Hares exhibit variation in timing of pelage change across 

western North America, but variation is low in any specific 

location, and timing appears to be genetically controlled 

and linked to photoperiod (e.g., Hall and Kelson 1959; 

Zimova et al. 2014). Timing of pelage change is critical 

for hare survival, because mismatches—a white hare on a 

dark background and vice versa—cause most hares to die 

from predation (Hodges 2000) (fig. 9.2). Initiation of pelage change is apparently driven by photoperiod rather than 

background color, so the ability of hares to shift the timing 

of pelage change to match patterns of snow cover is limited 

(Mills et al. 2013). Given projections of snow cover by 2100 

(see chapters 3 and 4), current patterns of pelage change in 

the Northern Rockies region will be mismatched with the 

period of snow cover. Unless a significant change occurs 

in the population genetics of hares, they will be the wrong 

color for about 2 months per year (one month in spring, one 

month in fall) in the region (Mills et al. 2013).

Both lynx and hares require specific amounts and duration of winter snow. An example of this for lynx occurs in 

Minnesota, where current and historical populations are limited to the “arrowhead” north of Lake Superior (McKelvey 

et al. 2000; Schwartz et al. 2004). This area is characterized 

by lake-effect snow, and outside of it, bobcats dominate 

and lynx are not found. Both lynx and hares require forests 

with dense understory canopies. In western Montana, lynx 

and hares use older spruce-fir forests. If climate change and 

associated disturbance reduce the abundance of these forest 

types, habitat loss could be significant, reducing populations 

of lynx and hares.

Fisher

The fisher (Martes pennanti) is a mid-sized, forestdwelling mustelid. The range of the fisher covers much of 

the boreal forest in Canada, a broad area of the northeastern 

United States extending from the Lake States to Maine, and 

a scattered distribution in the western United States. Males 

and females are similar in appearance, but the males are 

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larger. Males are 35 to 47 inches long and weigh 8 to 13 

pounds; females are 30 to 37 inches long and weigh 4 to 6 

pounds (Powell 1993).

Fishers are common in the eastern United States and 

are often associated with urban environments, but they are 

uncommon in the western United States and apparently 

have very specific habitat associations. Although the current 

distribution of fishers is reduced from the historical range, 

populations have typically been disjunct. Genetic studies 

have shown that fisher populations in California have been 

historically isolated from those in Washington, and fishers in 

the southern Sierra Nevada have been isolated from those in 

the Klamath region (Tucker et al. 2012). Fishers in Montana 

contain unique haplotypes (DNA variations that tend to be 

inherited together) not found elsewhere (Schwartz 2007; 

Vinkey et al. 2006) and therefore were apparently isolated 

both from large populations in northern British Columbia 

and from coastal populations in Washington. Common attributes for resting sites across eight studies of western fishers 

were steep slopes, cool microclimates, dense forest canopy 

cover, high volume of logs, and prevalence of large trees 

and snags (Aubry et al. 2013). Although these features are 

important for managing fisher habitat, they do not necessarily explain the fragmented historical distribution in the West 

(Tucker et al. 2012).

Fishers have long been thought to have specific climatic 

associations. Krohn et al. (1995) compared fisher and 

marten (Martes americana) distributions in the Sierra 

Nevada, and found that areas occupied predominantly by 

marten were closely associated with forested areas with the 

deepest snow (>9 inches per winter month), whereas areas 

occupied predominantly by fishers were forested areas with 

low monthly snowfall (<5 inches). There is direct evidence 

that fishers avoid deep snowpack (Krohn et al. 1995, 2005; 

Raine 1983) and that deep snow can limit fisher dispersal 

(Carr et al. 2007). Fishers also avoid dry habitats (Jones and 

Garton 1994; Schwartz et al. 2013).

Presence in warmer, wetter forests is apparently common 

in distributions of fishers at both the macroscale and fine 

scale in the western United States, although large populations in northern interior British Columbia and Alberta are 

not associated with these specific climates. Therefore, defining fisher habitat in climatic terms and projecting future 

habitat is more challenging than for animals with more obvious climatic associations (Copeland et al. 2010; McKelvey 

et al. 2011).

In a recent modeling study of fisher habitat in an area 

consistent with its distribution in the Northern Rockies, 

Olson et al. (2014) built occurrence models for fisher populations in northern Idaho and western Montana that included 

variables such as canopy cover, climatic variables such as 

minimum winter temperature, and topographic variables 

such as slope. They found that most of the variability in 

the model was explained by mean annual precipitation (34 

percent), topographic position index (29 percent), and mean 

temperature of the coldest month (27 percent). Therefore, 

fisher habitat was projected to be best in areas with high 

annual precipitation, low relief, and mid-range values for 

mean temperature in the coldest month. Krohn et al. (1997) 

and Olson et al. (2014) projected similar areas of fisher 

habitat and in similar places.

Olson et al. (2014) used downscaled data from a single 

GCM (Hadley Centre Coupled Model, version 3; Collins et 

al. 2001) and two emissions scenarios (A2-high, B2-low; 

IPCC 2007b), projecting habitat for 2030, 2060, and 2090. 

At the macroscale, results for both scenarios are similar: In 

the near term, habitat currently occupied by fishers might 

improve, but by 2090, habitat in areas that are currently 

occupied (primarily central Idaho) decline sharply, and 

new habitat is created to the east in northwestern Montana. 

The primary difference between the scenarios at this level 

of detail is the rate at which changes occur. The change 

is visibly apparent by 2060 in the A2 scenario, but not in 

the B2 scenario. As habitat shifts, it becomes increasingly 

fragmented, and the amount of usable habitat is strongly 

affected by how acceptable minimum patch size is defined 

(Olson et al. 2014).

Olson et al. (2014) bracketed the emissions scenarios, 

providing some measure of the potential range of results, 

but between-model variability exceeds variability between 

emissions scenarios. In addition, the performance of specific 

GCMs varies considerably at the regional scale (Mote and 

Salathé 2010), and the Hadley family of GCMs is considered to be on the hot-dry side of climate projections for the 

Northern Rockies region (Alder and Hostetler 2014). As 

a result, details within the model can influence patterns of 

projected habitat.

There are other uncertainties about the ability of habitat 

components to track climate. Given that fishers are associated with mature forests, significant time lags may exist 

between the loss of current habitat and formation of new 

habitat in areas that currently are unsuitable. If large trees 

cannot survive the shift in climate, mature forests may become rare for many decades. In climatic zones suitable for 

fishers, forests may be dominated by young trees and shrubs 

whose suitability for fisher habitat is unknown. Therefore, 

projections in Olson et al. (2014) are an optimistic view of 

habitat availability under climate change, and it is uncertain 

if fishers would disperse into new habitat should such 

changes occur.

Moose

Unlike Canada lynx or snowshoe hares, not all species 

with northern distributions have cold-weather related traits. 

Some organisms with broad historical distributions are currently limited to northern distributions because of southern 

extirpation, such as gray wolves (Canis lupus) and brown 

bears (Ursus arctos). These species are not considered to 

be strongly climate limited. Indirectly, cold climates lead 

to low densities of human populations in boreal forests and 

tundra, and interaction with large carnivores is therefore 

minimal. Were climates to warm, and people to relocate into 

these northern systems, this would obviously affect species 

such as wolves and brown bears.

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USDA Forest Service RMRS-GTR-374. 2018 361

For a second group of species, northern ranges are not 

defined by human impacts, but direct and indirect climate 

limits may not have been identified. Moose (Alces alces) 

are an example of a well-studied animal that has a northern 

distribution but whose dependence on boreal environments 

is not immediately obvious. We suspect that other species 

with northern distributions may exhibit similar constraints 

that define the southern extents of their ranges.

A limited amount of climate change research has been 

conducted on moose (Murray et al. 2006, 2012). Several factors have been identified as influencing the biogeographical 

distribution of moose including food supply, climate, and 

habitat. Based on metabolic research, moose are intolerant 

of heat but well adapted to cold, and summer temperatures 

may define their southerly distribution (Renecker and Hudson 

1986). When winter temperatures were greater than 23 °F 

or summer temperatures were greater than 57 °F, moose 

showed an increase in metabolism and heart and respiration 

rates (Renecker and Hudson 1986, 1990), reduced feed intake 

(Belovsky and Jordan 1978; Renecker and Hudson 1986), and 

reduced body weight (Renecker and Hudson 1986). When 

ambient air temperatures exceeded 68 °F, moose resorted 

to open-mouthed panting to regulate core body temperature 

(Renecker and Hudson 1986). Heat stress was particularly 

apparent in the spring when moose were still in their winter 

coats (Schwartz and Renecker 1997).

However, moose may be able to avoid being exposed to 

high midday summer temperatures. In Minnesota, Lenarz 

et al. (2009) found that temperature was highly correlated 

with moose survival, but winter temperature was more critical than summer heat. High temperatures in January were 

inversely correlated with subsequent survival and explained 

more than 78 percent of variability in spring, fall, and annual survival. In northern Minnesota, moose populations were 

not viable, largely because of disease- and parasite-related 

mortality (Murray et al. 2006). In nearby southern Ontario, 

however, moose populations were apparently viable with 

favorable growth rates (Murray et al. 2012). Warming temperatures favor white-tailed deer (Odocoileus virginianus) 

expansion into moose range, and increased transmission 

of deer parasites to moose (Lankester 2010). Given both 

physiological and biological stressors, separating direct and 

indirect climate effects is difficult (Murray et al. 2012).

Northern Bog Lemming

As the name implies, northern bog lemmings 

(Synaptomys borealis) inhabit wet meadows, bogs, and 

fens within several overstory habitat types (Foresman 

2012). Generally these wetlands have extensive sphagnum 

(Sphagnum spp.), willow (Salix spp.), or sedge components. 

These mammals were likely to occupy places that retained 

high water levels after the last glacial retreat (Foresman 

2012). Given their dependence on wet habitats, it follows 

that climate changes that decrease the amount of surface 

water will probably have negative impacts on northern bog 

lemmings. Management practices that maintain surface 

water may therefore be beneficial. However, documented 

studies of climate and management effects are lacking.

Pronghorn

The pronghorn (Antilocapra americana) is an ungulate 

native to the prairies, shrublands, and deserts of the western 

United States and occupying a broad range of climatic 

conditions from southern Canada (Dirschl 1963) to Mexico 

(Buechner 1950). Although pronghorns occupy a broad climatic region and their diet is generalized, they are prone to 

epizootic diseases, notably bluetongue (a viral disease transmitted by midges [Culicoides spp.]) (Thorne et al. 1988). 

Bluetongue is thought to be cold-weather limited, and recent 

extensions of bluetongue in Europe have been attributed to 

climatic warming (Purse et al. 2005). Given their current 

range and food habits, the emergence of new disease threats 

caused by a warmer climate probably poses the greatest risk 

to pronghorns.

Pygmy Rabbit

The pygmy rabbit (Brachylagus idahoensis) is one of 

the smallest leporids in the world and is endemic to big 

sagebrush (Artemisia tridentata) (Katzner and Parker 1997), 

which is critical for food and cover. In southeastern Idaho, 

areas selected by pygmy rabbits had a significantly higher 

woody cover and height than other areas, with lower quantities of grasses and higher quantities of forbs. Sagebrush was 

eaten throughout the year, composing 51 percent of the diet 

in summer and 99 percent in winter (Green and Flinders 

1980). These findings are similar to those reported for southern Wyoming (Katzner and Parker 1997) and Utah (Edgel 

et al. 2014). In addition, areas used by pygmy rabbits accumulate more snow than unused areas, and rabbits use the 

subnivean environment to reach food and avoid predators 

(Katzner and Parker 1997). The presence of significant snow 

for thermal protection may be important for winter survival, 

because of small body size, lack of metabolic torpor, and 

lack of food caching (Katzner and Parker 1997).

Structural characteristics of sagebrush are considered 

more important than food availability for pygmy rabbits 

(Green and Flinders 1980; Katzner and Parker 1997). 

Although large, dense sagebrush would be expected to 

be associated with older stands, Edgel et al. (2014) found 

no difference in age between occupied and unoccupied 

sites; structure was important, but age was not. As a result, 

processes that reduce the size and density of sagebrush are 

likely to have negative effects on pygmy rabbits, and processes that fragment sagebrush stands may decrease habitat 

quality. For example, Pierce et al. (2011) found that burrows, observed rabbits, and fecal pellets decrease in density 

with proximity (<300 feet) to edges.

Paleoecological studies show that both sagebrush and 

pygmy rabbits are sensitive to climate change. Both species 

decreased in the mid-Holocene, characterized in the Great 

Basin by extreme aridity (Grayson 2000). Big sagebrush 

is sensitive to fire, and 100 percent mortality and complete 

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362 USDA Forest Service RMRS-GTR-374. 2018

stand replacement after burning are common (Davies et 

al. 2011; see Chapter 7). In addition, big sagebrush cannot 

resprout from the root crown after a fire, so recruitment of 

sagebrush relies on wind dispersal of seeds from adjacent 

seed sources and on composition of the seedbank in the soil 

(Allen et al. 2008; Ziegenhagen and Miller 2009). Mountain 

big sagebrush (A. tridentata ssp. vaseyana) required 13 to 

27 years after spring prescribed burning to return to conditions suitable for pygmy rabbit habitat (Woods et al. 2013). 

In areas where fire has been suppressed for many decades, 

sagebrush habitat can be displaced by conifer incursion 

(Miller and Rose 1999).

Pygmy rabbits are likely to be sensitive to climate change 

for several reasons. First, they depend on a single species 

(big sagebrush) and habitat condition (tall, dense stands). 

Climatic variability has affected sagebrush communities and 

pygmy rabbits in the past (Grayson 2000), and this could 

happen again in the future. Second, pygmy rabbit habitat 

is sensitive to altered disturbance. Increased fire frequency 

and area burned are projected as the climate continues to 

warm (see chapters 6, 7, and 8). Finally, changes in winter 

snow depth could affect overwinter survival by altering the 

protection provided by the subnivean environment.

Townsend’s Big-Eared Bat

Climate change can affect foraging ability, drinking water availability, and timing of hibernation in bats (Sherwin 

et al. 2013). Townsend’s big-eared bats (Corynorhinus 

townsendii) generally require cavern-like structures for 

diurnal, maternal, and hibernation roosting, although they 

also use large tree cavities, buildings, and bridges (Gruver 

and Keinath 2003). They forage for insects along riparian 

and forest edge habitats (Fellers and Pierson 2002). Their 

distribution is apparently limited by the availability of suitable roosting sites, as western populations have declined 

(O’Shea and Vaughan 1999) coincidental with mine closings 

(Gruver and Keinath 2003). Townsend’s big-eared bats are 

not able to produce highly concentrated urine (Geluso 1978) 

and therefore require daily access to water sources for drinking (Gruver and Keinath 2003). Constructed water holes and 

mining ponds may serve as water sources (Geluso 1978); 

metal contaminants in the latter may cause some bat mortality (Pierson et al. 1999).

Bioaccumulation of pesticides in fat tissue apparently 

is one cause of declines in Townsend’s big-eared bat 

populations (Clark 1988). Human activities that reduce 

moth populations can also negatively affect bat populations 

because moths are a primary food source of Townsend’s bigeared bats (Burford and Lacki 1998; Whitaker et al. 1977). 

Bats may be especially sensitive to human disturbance during hibernation (Thomas 1995).

In Colorado, the reproductive success of bats of the 

Myotis genus declined during warmer and drier conditions, 

which are projected to be typical of future climatic conditions (Adams 2010). However, in other instances, warmer 

spring temperatures have led to earlier births, which promotes juvenile survival (Lucan et al. 2013). Higher summer 

precipitation may reduce reproductive success (Lucan et al. 

2013). Future warming may also reduce the effectiveness of 

some bat echolocation calls (Luo et al. 2014).

Ungulates (Elk, Mule Deer, White-tailed Deer)

Rocky Mountain elk (Cervus canadensis), Rocky 

Mountain mule deer (Odocoileus hemionus hemionus), and 

white-tailed deer (O. virginianus) provide the core of big 

game hunting in the Northern Rockies region. All three have 

very broad ranges in North America. The current range for 

elk, which includes most of the Rocky Mountain West, also 

includes areas in the eastern and southwestern United States 

that were historically occupied by other subspecies. Rocky 

Mountain mule deer extend from the Yukon to northern 

Arizona. White-tailed deer extend across most of North 

America and into northern South America and include 38 

recognized subspecies (De la Rosa-Reyna 2012).

Based on their broad ranges, it is clear that all three 

species exhibit a high degree of flexibility toward habitat. 

Habitat use by elk in forested areas is associated with edges 

(Grover and Thompson 1986; Irwin and Peek 1983; Thomas 

et al. 1979, 1988) in which areas containing high-quality 

forage and areas with forest cover are in proximity. In open 

habitats, they select areas of high vegetative diversity with 

intermixed patches of shrubs and grasslands (Sawyer et al. 

2007). Both patterns of habitat use are apparently maximized by a disturbance regime with spatial heterogeneity at 

relatively fine scales.

A study of Rocky Mountain mule deer found that home 

range size increased in areas with few large patches and 

was smallest in fine-grained vegetation mosaics (Kie et al. 

2002). Mule deer depend on disturbance to create forage 

(e.g., Bergman et al. 2014), but the size and juxtaposition of 

patches are important. Fine-grained disturbance mosaics are 

apparently optimal for white-tailed deer, especially in areas 

where thermal cover is important. In the Northern Rockies 

region, thermal cover prevents heat loss during winter, 

although in warmer climates, thermal cover reduces daytime 

heating. In Texas, male white-tailed deer chose areas with 

high cover and poor foraging opportunities during the midday, but chose areas with higher forage quantities during 

crepuscular and nocturnal periods (Wiemers et al. 2014).

Ungulates generally respond positively to disturbance 

(fig. 9.5), but the types of disturbance and the resulting 

landscape condition and species composition are equally 

important. Just as wildfire intensity affects patchiness in the 

postfire landscape, it also affects which plant species are 

likely to revegetate burned areas. For example, Emery et al. 

(2011) found that at lower temperatures several native plant 

species exhibited enhanced germination, whereas nonnative 

plant species did not. Vegetation growth after disturbance 

is important where nonnative species are common. For 

example, Bergman et al. (2014) found that treatments that 

removed trees and controlled weeds produced better mule 

deer habitat than treatments that removed only trees.

Climate change is expected to alter fire regimes, but for 

ungulates the exact nature of those changes will be critical. 

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 363

For example, in the Greater Yellowstone Area subregion, 

wildfires are infrequent, large, and intense. If climate change 

causes more frequent fires (Westerling et al. 2011), then the 

landscape will be patchier compared to the current condition, 

and the distribution and abundance of forest species could 

change. In the short term, novel fire-climate-vegetation 

relationships can be expected. In the long term, the effects of 

altered vegetation on ungulate populations are uncertain, but 

it is unlikely that there will be highly negative consequences.

Wolverine

The wolverine (Gulo gulo) is the largest mustelid, occurring throughout the Arctic, as well as subarctic areas and 

boreal forests of western North America and Eurasia. At the 

southern extent of its distribution in North America, populations occupy peninsular extensions of temperate montane 

forests. Monitoring programs in Fennoscandia (Flagstad et 

al. 2004) and surveys in Canada (Lofroth and Krebs 2007) 

inform our understanding of wolverine occurrence in those 

regions, but the limits of wolverine distribution in other portions of its range are less understood.

Wolverines are often considered to be generalists with 

respect to habitat, and their occurrence has been associated 

with great distance from human development (Banci 1994; 

May et al. 2006; Rowland et al. 2003). However, unlike 

brown bear and gray wolf, whose northern distributions are 

the result of recent human hunting and habitat alteration, 

there is no historical evidence for wolverine presence in areas 

not characterized by arctic or boreal conditions (Aubry et al. 

2007). Fossil evidence is consistent with this understanding 

(Alvarez-Lao and Garcıa 2010), and wolverines apparently 

have always been associated with cold northern climates.

Wolverines den in snow, and deep snow throughout 

the denning period is thought to be essential (Magoun and 

Copeland 1998). The strong, perhaps obligate, relationship 

between wolverine den selection and deep snow in the late 

spring has been reinforced by recent study results (Copeland 

et al. 2010; Dawson et al. 2010; Inman et al. 2012). A proxy 

for spring snowpack (areas where snow persisted through 

mid-May) effectively describes den site selection, current 

range limits, and year-round habitat use at the southern periphery of the wolverine range (Copeland et al. 2010). These 

areas are associated with successful dispersal (Schwartz et 

al. 2009) and historical range (Aubry et al. 2007). Although 

not all biological aspects of this association are understood, 

its universal nature in both space and time indicate that snow 

persistence will be associated with future distributions as 

well. The association applies to populations in Alaska, Idaho, 

and Scandinavia, and it describes both historical and contemporary distributions. Wolverines apparently travel within 

these areas when dispersing and strongly minimize travel 

through low elevation habitat, so we can project both current 

and future travel routes based on altered snowpack.

McKelvey et al. (2011) modeled future spring snowpack 

within the Columbia, Upper Missouri, and Colorado River 

basins, and projected changes in habitat and connectivity associated with future landscapes based on existing wolverine 

habitat relationships (Copeland et al. 2010) and dispersal 

preferences (Schwartz et al. 2009). A projection derived 

from an ensemble mean of 10 GCMs under an intermediate 

emissions scenario (A1B) (Mote and Salathé 2010) was used 

to produce climate projections (Elsner et al. 2010; Littell et 

al. 2011). Historical data across the area were reconstructed 

following methods in Hamlet and Lettenmaier (2005), and 

changes from historical patterns were modeled by using the 

“delta” method of downscaling, resulting in regionally averaged temperature and precipitation change for 2030–2059 

and 2070–2099. Downscaled climate data were used as inputs 

to the Variable Infiltration Capacity (VIC) model (Hamlet 

and Lettenmaier 2005; Liang et al. 1994), which was used to 

project snowpack. Historical modeled snowpack depth was 

Figure 9.5—Ungulates generally 

respond favorably to 

wildfires that create patchy 

habitat, especially if forage 

availability improves, as 

shown in this photo of an 

elk browsing adjacent to a 

recently burned lodgepole 

pine forest (photo: Jeff Henry, 

National Park Service).

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
364 USDA Forest Service RMRS-GTR-374. 2018

fit to most closely match the persistent snow cover data from 

Copeland et al. (2010), and this fit was then used to identify 

areas of future habitat for wolverines.

In the Columbia and Upper Missouri River basins, where 

most of the Northern Rockies region is located, snowpack 

projection indicated a loss of 35 and 24 percent, respectively, 

for spring snow by the mid-21st century, and 66 and 51 

percent, respectively, by the end of the century. Central 

Idaho was projected to lose nearly all snow by the end of the 

century, whereas northern Montana, the southern Bitterroot 

Mountains, and the Greater Yellowstone Area retained significant spring snow (McKelvey et al. 2011). The ensemble 

mean model output was similar to results associated with the 

Parallel Climate Model (a cool extreme; U.S. Department of 

Energy and National Science Foundation 2004), but at the 

warm extreme, little spring snow was retained at the end of 

the century. A connectivity model (Schwartz et al. 2009) in 

conjunction with ensemble climate model projections indicated that all remaining habitat would be genetically isolated 

by the end of the 21st century (McKelvey et al. 2011).

The threshold between rain and snow causes estimates 

of snowpack loss to differ greatly between GCMs because 

timing of moisture and the temperature when it occurs affect 

model performance. Cool models (e.g., Goddard Institute for 

Space Studies model E; Schmidt et al. 2006) indicate increases in January snowpack at high elevation (e.g., Yellowstone 

Plateau, Colorado) through the mid-21st century, whereas 

warmer models (e.g., Model for Interdisciplinary Research on 

Climate; Watanabe et al. 2011) show large losses in snowpack 

across all regions (Alder and Hostetler 2014). All models, 

including the coolest and wettest, indicate a continuing reduction in spring snow, a pattern that has been ongoing since at 

least the 1950s (Mote et al. 2005).

Birds

Brewer’s Sparrow

Brewer’s sparrow (Spizella breweri) is apparently a 

sagebrush obligate during the nesting period when nest 

occupancy is positively related to tall, dense stands of sagebrush (Petersen and Best 1985; Reynolds 1981) (fig. 9.6). 

In areas where other sagebrush-obligate species exist (e.g., 

sage thrasher [Oreoscoptes montanus]), these sparrows may 

compete for nest locations (Reynolds 1981). In many areas, 

however, Brewer’s sparrow is the most abundant bird species 

(Norvell et al. 2014). Some consider the closely related timberline sparrow (S. breweri taverneri) to be a separate species 

(i.e., S. taverneri) or subspecies but, in any case, no genetic 

mixing occurs between the alpine and sagebrush variants 

(Klicka et al. 1999).

Reasons for the obligate relationship of Brewer’s sparrow with sagebrush are obscure. Although this relationship 

appears to be robust, especially patterns of nest occupancy 

(Petersen and Best 1985), evidence for why Brewer’s sparrow nests in sagebrush rather than in other brush species is 

lacking. Therefore, we rely on correlative associations to 

project climate change effects and cannot speculate as to the 

flexibility of this species to shift to alternative shrub species 

should sagebrush become scarce.

Brewer’s sparrow populations appear to be reasonably 

stable range-wide, although they have been in decline in 

some areas in Colorado (USGS 2013). Although Brewer’s 

sparrow selects for areas with tall, dense sagebrush, sparrow 

abundance was unaffected by treatments designed to modify 

sagebrush cover and improve habitat for greater sage-grouse 

(Norvell et al. 2014). Similarly, a study of the effects of 

(nonnative) smooth brome (Bromus inermis) found that 

nest success was higher in areas with brome establishment 

(Ruehmann et al. 2011). In general, the effects of climate 

change on Brewer’s sparrow will probably depend to a great 

degree on changes in the distribution, abundance, composition, and structure of sagebrush communities. Increased 

wildfire is likely to reduce the distribution, abundance, and 

age of sagebrush stands in a warmer climate. Within sagebrush communities, Brewer’s sparrows do exhibit flexibility 

in response to nest predation, shifting locations of sequential 

nests in response to previous predation (Chalfoun and Martin 

2010).

Flammulated Owl

The flammulated owl (Otus flammeolus) is a nocturnal 

owl, approximately 6 inches long with a 14-inch wingspan. 

It is migratory but breeds in montane areas across much 

of western North America, ranging from southern British 

Columbia to central Mexico (Ridgely et al. 2003). It is a cavity nester, associated with mature forests with large diameter 

Figure 9.6—Because climate change is expected to reduce 

the extent of mature sagebrush through increased wildfire, 

sagebrush-obligate species such as Brewer’s sparrow 

(shown here) and greater sage-grouse may have less nesting 

habitat in the future (photo: Tom Koerner, U.S. Fish and 

Wildlife Service). 

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 365

trees. It is also associated with open forests, but does not 

appear to be specific to any particular tree species. In New 

Mexico, it is found in pinyon pine (Pinus edulis) (McCallum 

and Gehlbach 1988), ponderosa pine (P. ponderosa) (Bull et 

al. 1990; Linkhart et al. 1998), and Douglas-fir (Powers et al. 

1996; Scholer et al. 2014) forest. In the Sierra Nevada, it has 

been associated with (from low to high elevation) black oak 

(Quercus kelloggii), mixed-conifer, Jeffrey pine (P. jeffreyi), 

white fir (Abies concolor), and red fir (A. magnifica) forest 

(Stanek et al. 2011).

Flammulated owls are thought to be obligate secondary 

cavity nesters, although it has been anecdotally observed to 

nest in the ground (Smucker and Marks 2013). Flammulated 

owls feed almost exclusively on insects, primarily 

Lepidoptera, which they gather from trees, on the ground, 

or in flight (Linkhart et al. 1998). During the nesting period, 

males are single-trip, central-place foragers, so the energetics 

of prey selection are important; distance traveled and energy 

content of prey differ by forest type. Little information is 

available on the diet of flammulated owls and their relationships to forest habitat. Interactions with other owl species are 

apparently minimal (Hayward and Garton 1988).

The extensive latitudinal range of flammulated owls, lack 

of specific forest associations, and generalized insect diet 

indicate that straightforward links to specific climatic regimes 

are unlikely. If climate change is to affect flammulated owls, 

then it will most likely be through disturbance processes that 

remove large diameter trees. Shifts to denser forest structure 

would be problematic for this species, but there is little evidence that this would occur, because drought and wildfire are 

projected to increase throughout the Northern Rockies (Alder 

and Hostetler 2014). As with other long-lived owl species 

(Linkhart and Reynolds 2004), flammulated owl populations 

will be very sensitive to adult survival (Noon and Biles 1990).

Greater Sage-Grouse

Greater sage-grouse (Centrocercus urophasianus) is the 

largest grouse in North America (Mezquida et al. 2006). It is 

considered an obligate with sagebrush (Miller and Eddleman 

2001). Its distribution is currently about half of its presettlement range (Schroeder et al. 2004), and many populations 

have been steadily declining in recent decades (Braun 1998; 

Connelly and Braun 1997; Connelly et al. 2004). In some 

areas, land conversion that eliminated sagebrush apparently 

has caused the declines (Connelly et al. 2004; Miller and 

Eddleman 2001). Extirpation of sage-grouse is more likely in 

areas with high human population densities, land conversion 

to cropland, severe droughts (Aldridge et al. 2008), sagebrush 

displacement by conifers, and corvid predation. It is also 

more likely in areas with less than 25 percent sagebrush cover 

near the edge of the historical range.

Declines in sage-grouse have also occurred in areas still 

dominated by sagebrush (Miller and Eddleman 2001). In 

addition to reduced sagebrush cover, declines have been attributed to nonnative plants (Connelly et al. 2004; Knick et al. 

2003; Wisdom et al. 2002), energy exploration and extraction 

(Braun et al. 2002; Doherty et al. 2008; Holloran et al. 2005; 

Lyon and Anderson 2003; Walker et al. 2007a), grazing (Beck 

and Mitchell 2000; Hayes and Holl 2003), altered fire regimes 

(Connelly et al. 2000, 2004), and a warmer climate (Neilson 

et al. 2005). In recent years, West Nile virus has also been 

implicated (Naugle et al. 2004, 2005; Walker et al. 2007b).

Assessing the effects of climate change on this species 

is challenging because so many factors potentially affect 

sage-grouse population dynamics. Nevertheless, Schrag et 

al. (2011) produced a detailed climate change assessment for 

greater sage-grouse that evaluated changes in distribution 

of sagebrush and transmission of West Nile virus. They first 

built bioclimatic models for sagebrush distribution, then modeled West Nile spread based on temperature thresholds. They 

used six GCMs and one emissions scenario (A1B), and GCM 

output was statistically downscaled to 7.5-mile pixels. Both 

the envelope model and temperature thresholds were projected to 2030 based on the downscaled GCM output. Results 

varied greatly across models, but it was concluded that the 

cumulative effects of projected climate change on both sagebrush and West Nile virus transmission would reduce suitable 

sage-grouse habitat in the Northern Rockies and northern 

Great Plains (Schrag et al. 2011). Sage-grouse require large 

areas of mature sagebrush, so future increases in wildfires are 

expected to significantly reduce habitat.

Creutzburg et al. (2015) evaluated the likely trajectory 

of greater sage-grouse habitat in southeastern Oregon. They 

simulated the effects of climate change, disturbance, and 

cheatgrass (Bromus tectorum) invasion by coupling a linked 

dynamic global vegetation model, climate envelope model, 

and state-and-transition simulation model, based on three 

climate models chosen to cover a range of possible futures. In 

the near term, loss of sagebrush from wildfire and cheatgrass 

invasion leads to habitat deterioration. In all three climate 

projections, however, native shrub-steppe communities 

increased circa 2070, leading to habitat improvement. In this 

simulation, all projected climate futures had better long-range 

prospects for sage-grouse than was simulated based on current climate.

Harlequin Duck

Harlequin ducks (Histrionicus histrionicus) in the 

Intermountain West breed and summer on fast-flowing 

mountain streams and winter on rocky coastal areas 

(Robertson and Goudie 2015). In Grand Teton National 

Park, breeding pairs used streams with dense shrubs along 

the banks (Wallen 1987). During summer they feed primarily on larval insects on stream bottoms and in winter on a 

variety of small food items including snails, small crabs, 

barnacles, and fish roe (Robertson and Goudie 2015). They 

are relatively rare in Montana, with a concentration in Upper 

McDonald Creek in Glacier National Park (Reichel 1996). 

Climate change may alter the timing, duration, and levels of 

streamflows. In Glacier National Park, harlequin duck reproductive success declined with higher and less predictable 

streamflows (Hansen 2014).

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366 USDA Forest Service RMRS-GTR-374. 2018

Mountain Quail

The mountain quail (Oreortyx pictus) is a small grounddwelling bird that occupies upland forest and woodland 

habitats in the western United States and northern Mexico 

(Brennan et al. 1987). In the Pacific Northwest, its range 

extends into deep canyons such as Hells Canyon of the 

Snake River (Pope and Crawford 2004), where populations 

of the species have been declining. Population augmentation 

through translocation is common. Population studies have focused on survival, but connections to climate-related change 

are minimal. Stephenson et al. (2011) found that climaterelated variables were important to survival, with lower 

survival being linked both to hot, dry conditions and to cold 

winter weather. Seasonal movements to avoid snowpack led 

to increased rates of movement, which were also important 

predictors of survival.

Pygmy Nuthatch

The pygmy nuthatch (Sitta pygmaea), a bird about 4 

inches long, is found throughout montane coniferous forests 

in western North America and as far south as central Mexico 

(McEllin 1979; Ridgely et al. 2003). It is a cavity nester, 

often associated with ponderosa pine forests (McEllin 

1979) but also found in other forest types such as quaking 

aspen (Populus tremuloides) (Li and Martin 1991). Pygmy 

nuthatches can exhibit a social structure of cooperative 

breeding in which “helpers” aid breeding birds by feeding 

the incubating female, feeding nestlings and fledglings, and 

defending nesting territory (Sydeman et al. 1988).

Pygmy nuthatches nest in cavities in both live and dead 

trees, as observed at a study site in Arizona (Li and Martin 

1991), and population responses to disturbance are modest. 

For example, Hurteau et al. (2008) found that population 

densities across a variety of thinning and fuels treatments 

at a study site in Arizona remained constant except in thinand-burn treatments, where densities increased by more than 

500 percent. In a study of the interior western United States, 

Saab et al. (2007) found that nuthatches showed a negative 

response to fire the first year after wildfire, but a neutral 

response in subsequent years. Due to their apparent neutral 

response to disturbance, coupled with flexibility in habitat 

and wide latitudinal range, it is difficult to project whether 

they will respond positively or negatively to climate change. 

Extirpation of the pygmy nuthatch due to climate change 

appears unlikely, other than from the effects of land-use 

conversion from forest to nonforest.

Ruffed Grouse

Ruffed grouse (Bonasa umbellus) are characterized by a 

boreal distribution that includes peninsular extensions into 

the Rocky Mountains and Appalachian Mountains (USGS 

2014). Throughout much of their range, ruffed grouse occupy quaking aspen (Populus tremuloides) forest (Kubisiak 

1985; Stauffer and Peterson 1985; Svoboda and Gullion 

1972), which provides important food sources (Jakubas and 

Gullion 1991). Although ruffed grouse exist in forests that 

contain no aspen (e.g., oak-dominated forest) (Haulton et al. 

2003), they are mostly limited to aspen habitats in many areas of the West (e.g., Mehls et al. 2014). Ruffed grouse were 

identified as a species of concern in the Northern Rockies in 

the context of aspen-dominated forest, so we focus here on 

the use of aspen by ruffed grouse.

In central Wisconsin, ruffed grouse densities were highest in young (<25 years) aspen stands (Kubisiak 1985). 

Similarly, ruffed grouse preferred stand structures characteristic of early successional stages in Idaho (Stauffer and 

Peterson 1985) but also use aspen stands of all ages (Mehls 

et al. 2014). Thus, optimal grouse habitat consists of aspen 

forests with stands in a variety of age classes, including a 

large component of young stands.

Aspen may be sensitive to heat and drought in some 

locations (Anderegg et al. 2013; Huang and Anderegg 

2011). Although higher temperatures are expected to cause 

increased stress in aspen, differences in forest structure and 

age affect the relationship between aspen mortality and 

drought (Bell et al. 2014), and mortality can be reduced by 

controlling stand densities and ages and limiting competition from conifers. If climate change causes decreased 

extent of aspen in the Northern Rockies region, reduced 

habitat would have detrimental effects on ruffed grouse 

populations. However, significant options exist to mitigate 

these changes through silviculture that favors aspen over 

conifers and through active manipulation of stand densities 

and ages.

Amphibians

Columbia Spotted Frog

The Columbia spotted frog (Rana luteiventris) breeds in 

montane ponds throughout western North America (Green 

et al. 1996, 1997) (fig. 9.7). Funk et al. (2008) built a 

phylogeny for this species based on samples across western 

North America. Populations separated into three distinct 

clades; within the Northern Rockies region, all samples 

were associated with the northern clade and were fairly 

closely related. The effects of climate change on Columbia 

spotted frogs are unclear. In Utah, the frog was more likely 

to occur in persistent, shady ponds that maintained constant 

temperatures (Welch and MacMahon 2005). In Yellowstone 

National Park, pond desiccation led to sharp declines in frog 

populations (McMenamina et al. 2008).Throughout their 

range, populations in large stable water bodies were doing 

well, whereas those in smaller more ephemeral ponds were 

subject to rapid declines (Hossack et al. 2013). In Montana, 

warmer winters were associated with improved reproduction 

and survival of Columbia spotted frogs (McCaffrey and 

Maxell 2010). This species does not appear to be sensitive 

to stand-replacing fires (Hossack and Corn 2007).

Columbia spotted frog populations are stable in areas 

with stable water supplies, and are capable of rapid population expansion into restored wetlands (Hossack et al. 2013). 

However, the amphibian chytrid fungus (Batrachochytrium 

dendrobatidis, hereafter referred to as Bd), is prevalent in 

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USDA Forest Service RMRS-GTR-374. 2018 367

many populations (Pearl et al. 2009; Russell et al. 2010) and 

warming waters would, in most systems, favor Bd (see discussion on western toad). Although the fungus is common, 

the population effects of infection are unclear.

Western Toad

Western toads (Anaxyrus boreas) are montane amphibians broadly distributed across the western United States 

(Muths et al. 2008); in the southern Rocky Mountains, the 

subspecies boreal toad (A. b. boreas) is recognized. The 

western toad has suffered apparently widespread declines, 

particularly at the southern extent of its range (Corn et al. 

2005), a phenomenon well documented in Colorado (Carey 

1993). This species suffers from amphibian chytrid fungus, 

which is often fatal. Laboratory studies of Bd have found 

that it grows optimally at 63 to 77 °F, and colonies are killed 

at 86 °F (Piotrowski et al. 2004). Although Bd can grow 

in temperatures as cold as 39 °F, warming waters would 

increase its prevalence.

In a study across Colorado, Wyoming, and Montana, 

Bd was consistently found in western toad tissues, and was 

more prevalent in warmer, lower elevation sites (Muths 

et al. 2008). A warmer climate may allow Bd to spread to 

higher elevations and become even more widespread. But 

there is some question about how susceptible the western 

toad is to the effects of Bd because increased mortality is 

not always associated with high infection rates. Recent 

studies indicate that the skin of the toad contains bacterial 

colonies that inhibit Bd (Park et al. 2014).

Assessing Subregional 

Differences in Vulnerability

When considering how climate change would affect 

wildlife populations in their subregion, Northern Rockies 

Adaptation Partnership (NRAP) workshop participants tended 

to think in terms of pathways through which climate could 

exert an influence (fig. 9.1, black text and arrows). These 

pathways can interact with each other, and with population 

characteristics (fig. 9.1, blue text and arrows) to produce 

an effect on the population of interest (fig. 9.1, red text). 

However, a given pathway influences multiple species, and 

multiple pathways influence a given species. Following is a 

summary of the subregional workshop discussions.

Upper temperature thresholds for moose were discussed 

for the Greater Yellowstone Area (GYA) subregion. This was 

the only species and subregion with a discussion of direct 

physiological sensitivities to climate. However, it was noted 

in all subregions that there is a general lack of understanding of direct physiological sensitivities to climate for most 

wildlife species. Even when these sensitivities have been 

measured (e.g., the lower thermoneutral limits for wolverines 

[e.g., Iversen 1972]), however, it is unclear how this laboratory-derived knowledge can be interpreted in the context of 

habitat use and demographic performance.

Position within a species’ niche can influence population 

vulnerability. Some species are at the climatic limits of their 

range in particular subregions. Exposure to climate change in 

these places is likely to have a strong effect on the ability of 

a species to persist, whereas the same amount of change in 

the center of its range probably would have less effect. The 

Western Rockies and Central Rockies subregions are at the 

junction of maritime and continental climates, and many species are at the edges of their ranges. For example, participants 

in the Central Rockies workshop discussed how future climate 

change is expected to increase habitat suitability for the fisher, 

such that this species may expand its range into the subregion.

Some species had different habitat associations in different subregions. For example, in the GYA, ruffed grouse was 

linked to aspen habitat but was associated with a broader 

range of habitats in the Central Rockies subregion. Therefore, 

ruffed grouse was seen as more sensitive to climate effects on 

aspen in the GYA than in the Central Rockies.

The importance of previous habitat loss, potentially caused 

by recent warming, differed across the subregions. In the 

Eastern Rockies subregion, extensive lodgepole pine (Pinus 

contorta var. latifolia) mortality has been caused by mountain 

pine beetle (Dendroctonus ponderosae); amplified pine beetle 

outbreaks are probably the result of warmer winters (Bentz et 

al. 2010). Cavity nesting birds were thought to be more sensitive to potential future habitat loss because they have already 

lost a substantial portion of their habitat. Prior habitat loss 

was not discussed in the other subregions.

Another pathway for habitat loss discussed in the Central 

Rockies workshop was an increase in invasive species. For 

example, flammulated owls feed on insects that depend on 

Figure 9.7—Warmer air temperature and less snowpack are 

expected to decrease the presence of shallow water during 

the summer, reducing habitat for the Columbia spotted 

frog (shown here) and western toad. Higher air and water 

temperatures may also increase infections from amphibian 

chytrid fungus (photo by Roger Myers, Alaska Department 

of Fish and Game).

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
368 USDA Forest Service RMRS-GTR-374. 2018

understory plant composition, and that composition could 

be altered by increased abundance of invasive plants such as 

cheatgrass.

Negative effects on wildlife populations from an increase 

in disease occurrence and transmission caused by climate 

change (e.g., West Nile virus) were discussed in three of the 

five subregions. Participants also noted that relatively little 

is known about disease ecology and the future potential for 

disease to affect wildlife populations.

Connectivity was a primary concern in four of the five 

subregions. Participants considered different scales of connectivity to be important: the ability for individuals to move 

through the landscape to meet their daily needs, the ability to 

complete seasonal migrations, and the ability to track potentially shifting habitat. Numerous indirect influences on each 

of those scales of connectivity were discussed.

Indirect pathways that increase vulnerability to climate 

change can also arise when a changing climate influences 

landscape configurations such that species are then more at 

risk from other stressors. Participants discussed the need to 

understand how potential shifts in residential development 

(e.g., into riparian habitats) in the GYA and Central Rockies 

subregions could affect wildlife. Changing demands for 

energy sources and the influence of energy development on 

wildlife habitat were discussed in the Central Rockies and 

Grassland subregions.

Another source of variation within the Northern Rockies 

region was the importance of multiple collaborative efforts focused on conservation issues in the Central Rockies 

subregion. USFS participants stated that these collaboratives 

increased their range of achievable management tactics.

There were differences in the amount of climate change 

expected (exposure), the response of individuals and populations to that change (sensitivity), and the ability of organisms 

and organizations to adapt to that change (adaptive capacity) 

across Northern Rockies subregions. However, participants 

agreed on the lack of understanding about mechanisms of climate influence. Identifying and contrasting the importance of 

pathways of climate influence across subregions can suggest 

potential mechanisms of climate influence. Hypotheses can be 

developed to account for these mechanisms, and management 

actions can be monitored to test those hypotheses. Based on 

the results of those tests, decisions can be made to continue 

with management actions, or develop new actions or hypotheses, creating an adaptive monitoring program (Lindenmayer 

and Likens 2009) and increasing knowledge of the needs and 

climate sensitivities of species (table 9.1). Sensitivities listed 

in tables 9.2 through 9.9 provide a starting point for identifying potential hypotheses.

Adapting Wildlife Management 

to the Effects of Climate Change

Adaptation to climate change for wildlife resources in 

NRAP subregions was focused on maintaining adequate 

habitat and healthy wildlife populations, and increasing 

knowledge of the needs and climate sensitivities of species. 

Workshop participants identified the major habitats in their 

subregion and then developed adaptation strategies for species they regarded as important and for which they believed 

viable management options exist. For example, participants 

in the GYA workshop discussed climate sensitivities of 

American pika, but decided not to work through adaptation 

options because they did not see how management efforts 

could influence pika population viability. Participants tended 

to address species or habitats that had not been covered in 

prior workshops, even if some were important in their subregion. Adaptation options are summarized according to major 

habitats (tables 9.2 through 9.7), which can then be associated 

with individual species (table 9.1).

Riparian habitats are important across the Northern 

Rockies region. The primary strategy for improving riparian 

habitat resilience is maintaining healthy American beaver 

populations (table 9.2). Beaver complexes can buffer riparian 

systems against both low and high streamflows, and provide 

habitat structure and foraging opportunities for multiple 

species. Nonriparian wetlands were discussed as important 

habitats, but no adaptation strategies were developed.

Quaking aspen habitats are common in the four western 

subregions and occur occasionally in the Grassland subregion. Aspen was identified as important because of its high 

productivity, role in structural diversity, and habitat for cavity 

nesting birds. In the GYA, ruffed grouse were identified as 

strongly tied to aspen habitats. Reduction in the distribution 

and abundance of aspen is projected for some locations 

(especially lower elevation) in a warmer climate (see Chapter 

6). The most common tactics for promoting aspen resilience 

were allowing wildfire or using prescribed fire in older aspen 

stands, providing protection from grazing, and reducing conifer encroachment in any age stand (table 9.3).

Dry ponderosa pine forests are common in the Central 

Rockies and Eastern Rockies subregions and provide habitat for cavity nesting birds such as the flammulated owl. 

Douglas-fir has encroached on these habitats as a result of 

fire exclusion, increasing vulnerability of pine to future fires. 

Tactics for promoting ponderosa pine resilience included 

reducing competition from Douglas-fir through understory 

burning and cutting, protecting mature stands, and planting 

ponderosa pine where it has been lost (table 9.4).

The Western Rockies and Central Rockies subregions 

support older, mesic forests because they experience a 

maritime climate influence (see Chapter 3). These forests, 

which provide important habitat for fisher, may have younger 

age classes (caused by increased disturbance; see Chapter 8) 

and different species composition in a warmer climate (see 

Chapter 6). Adaptation strategies included restoring historical 

structure, conserving current structure, and promoting potential future mesic forest habitats (table 9.5).

Mountain sagebrush-grassland habitat occurs in all regions 

except the Grassland. In the Western Rockies subregion, 

mountain sagebrush-grassland habitats are unique in that 

they have less of a sagebrush component, primarily occur in 

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 369

steep mountain canyons, and support populations of mountain 

quail. Differences in aspect have a strong influence on climate 

in these canyons. In a warmer climate, these habitats could 

lose some of their forb component, making them vulnerable 

to increased abundance of nonnative species (see Chapter 7). 

Specific tactics for restoring historical habitat and maintaining 

current habitat included managing fire, controlling nonnative 

species, and restoring formerly cultivated lands (table 9.6).

Sagebrush habitats are common in the Eastern Rockies, 

GYA, and Grassland subregions, supporting gallinaceous birds (greater sage-grouse, greater prairie chicken 

[Tympanuchus cupido], sharp-tailed grouse [T. phasianellus]), and pygmy rabbits, among other species. Tactics for 

maintaining adequate sagebrush habitat included managing 

fire, controlling nonnative species, preventing fragmentation, 

and restoring degraded habitat (table 9.7). Current focus on 

conservation of greater sage-grouse within sagebrush habitat 

in the western United States will benefit from including a 

climate-smart approach to management.

Developing on-the-ground management tactics requires 

understanding how climate change will influence species. In 

all subregions, and independent of habitat association, participants identified the need for better understanding of species 

requirements and the mechanisms of climate change impacts. 

In addition, connectivity and the potential for increases in 

disease were identified as important processes affecting multiple habitats and species in each subregion, although climate 

sensitivities of diseases are not well understood. Accordingly, 

several adaptation strategies were suggested to fill knowledge 

gaps (table 9.8). There is wide agreement on the need to better understand the mechanisms of climate sensitivities relative 

to the life histories of individual species. Examples of tactics 

to accomplish this objective include analyzing female Canada 

lynx home ranges to determine the necessary distribution and 

size of habitat patches, quantifying and monitoring pygmy 

rabbit distribution, and understanding sagebrush succession 

after fire. The influence of low snow years on wolverine 

Table 9.1—Species included in the Northern Rockies Adaptation Partnership vulnerability assessment, including species 

discussed at subregional workshops.

Habitat/Species

Western 

Rockies Central Rockies Eastern Rockies

Greater 

Yellowstone Area Grassland

Dry forest

 Flammulated owl X X

 Pygmy nuthatch X X X

Riparian/wetland

 American beaver X X X

 Moose X

 Northern bog lemming X

 Townsend’s big-eared bat X X X

 Harlequin duck X X

 Columbia spotted frog X X

 Western toad X X

Quaking aspen

 Avian cavity nesters X X X

 Ruffed grouse X

Sagebrush grasslands

 Pronghorn X

 Pygmy rabbit X

 Brewer’s sparrow X

 Greater sage-grouse X X

Mountain grasslands

 Mountain quail X

Mesic old-growth forest

 Fisher X X

Snow-dependent species

 American pika X

 Canada lynx X X

 Wolverine X X

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
370 USDA Forest Service RMRS-GTR-374. 2018

Table 9.2—Adaptation options that address climate change effects on riparian habitat and associated wildlife species in the 

Northern Rockies.

Sensitivity to climatic variability and change: Decreased streamflow reduces riparian vegetation, affecting food supply and 

habitat structure for multiple species. 

Adaptation strategy/approach: Improve riparian habitat by maintaining healthy beaver populations on the landscape. 

Specific tactic – A Specific tactic – B Specific tactic – C

Tactic Inventory current and 

potential habitat (include 

multiple factors).

Restore riparian habitat

e.g. plant willows, manage grazers, 

raise water level.

Translocation, manage 

trapping

Where can tactics be 

applied? (geographic)

Range-wide Suitable habitats range-wide Suitable habitats range-wide

Table 9.3—Adaptation options that address climate change effects on quaking aspen habitat and associated wildlife species in the 

Northern Rockies.

Sensitivity to climatic variability and change: A warmer climate will lower water tables, leading to loss of quaking aspen.

Adaptation strategy/approach: Promote aspen resilience.

Specific tactic – A Specific tactic – B Specific tactic – C

Tactic Promote disturbance (fire, 

cutting) in older aspen stands.

Protect from grazing (fencing, 

manage grazing).

Reduce conifer competition 

(fire, cutting) in any age aspen 

stand.

Where can tactics be 

applied? (geographic)

Range-wide Range-wide Range-wide

denning success is an example of a mechanistic relationship 

with climate that needs more data.

Connectivity, although not tied to a particular habitat type, 

is considered an important conservation strategy for most 

species in all Northern Rockies subregions, although climate 

influences on connectivity are uncertain. Several forms of 

connectivity were identified: daily, seasonal, dispersal, and 

range shift. Connectivity can be affected by changes in water 

supply, habitat loss, habitat shifts, vegetation phenology 

shifts, human population expansion and redistribution, and 

snowpack dynamics. Specific tactics for increasing knowledge that would enable the maintenance of connectivity 

include monitoring connectivity with genetic, tracking, and 

remote-sensing tools; identifying dispersal habitats; and identifying and removing or mitigating barriers to connectivity 

(table 9.9).

Disease is also important in most subregions, not tied to a 

particular habitat, and not well understood. Specific tactics for 

addressing disease include monitoring the presence of whitenose syndrome (caused by the fungus Pseudogymnoascus 

destructans) in bat hibernacula (ongoing through collaboration of the USFS, other agencies, and Northern Rocky 

Mountain Grotto), monitoring disease trends in moose and 

bighorn sheep, and coordinating with State agencies to monitor West Nile virus.

More specific details on adaptation strategies and tactics 

that address climate change effects on wildlife in each NRAP 

subregion are in Appendix 9A.

Acknowledgments

We thank all of the workshop participants without whose 

participation this chapter would not be possible. Their critical thinking regarding issues of wildlife and management 

response to climate change was both important and greatly 

appreciated. We would like to extend special thanks to Erik 

Beever, who assisted in writing the section on American 

pika.

References

Adams, R.A. 2010. Bat reproduction declines when conditions 

mimic climate change projections for western North America. 

Ecology. 91: 2437–2445.

Agee, J.K. 2000. Disturbance ecology of North American boreal 

forests and associated northern mixed/subalpine forests. In: 

Ruggiero, L.F.; Aubry, K.B.; Buskirk, S.W.; [et al.], eds. 

Ecology and conservation of lynx in the United States. Boulder, 

CO: University Press of Colorado: 39–82.

Alder, J.R.; Hostetler, S.W. 2014. USGS national climate change 

viewer. Washington, DC: U.S. Department of the Interior, U.S. 

Geological Survey. http://www.usgs.gov/climate_landuse/

clu_rd/apps/nccv_viewer.asp [Accessed May 1, 2015].

Aldridge, C.L.; Nielsen, S.E.; Beyer, H.L.; [et al.]. 2008. Rangewide patterns of greater sage-grouse persistence. Diversity and 

Distributions. 19: 983–994.

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 371 Table 9.4—Adaptation options that address climate change effects on dry forest (ponderosa pine) habitat and associated wildlife species in the Northern Rockies. Sensitivity to climatic variability and change: A warmer climate will potentially convert drier ponderosa pine to grassland; in addition, many ponderosa stands have converted to Douglas-fir because of fire exclusion and are susceptible to projected increases in fire frequency. Adaptation strategy/approach: Promote ponderosa pine resilience Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Reduce competition from Douglas-fir and grand fir (thin, burn) in current mature ponderosa pine stands. Frequent understory burning. Retain current mature and older ponderosa pine stands. Plant ponderosa pine where it has been lost. Where can tactics be applied? (geographic) Range-wide Range-wide Range-wide Range-wide Table 9.5—Adaptation options that address climate change effects on old-growth, mesic forest habitat and associated wildlife species in the Northern Rockies. Sensitivity to climatic variability and change: A warmer climate will create drier conditions and cause more wildfire, potentially eliminating old forest structure and mesic habitat. Adaptation strategy/approach: Maintain current habitat, restore historical habitat, and promote potential future inland maritime forest habitat. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Conserve current old-growth western redcedar and western larch, but reduce density to increase resilience to drought. Restore western white pine with a western redcedar understory to create future habitat. Maintain or create necessary structure in modeled future fisher habitat. Conserve current old-growth western redcedar and western larch, but reduce density to increase resilience to drought. Where can tactics be applied? (geographic) Northern Idaho, Kootenai, Bitterroot divide Where risk of loss is greatest (edge of range) Need redundancy across landscape to buffer against future fire or drought mortality. Northern Idaho, Kootenai, Bitterroot divide. Need redundancy across landscape to buffer against future fire or drought mortality. Mission side of Swan Range. Need redundancy across landscape to buffer against future fire or drought mortality. Northern Idaho, Kootenai, Bitterroot divide Where risk of loss is greatest (edge of range) Need redundancy across landscape to buffer against future fire or drought mortality.

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
372 USDA Forest Service RMRS-GTR-374. 2018 Table 9.6—Adaptation options that address climate change effects on mountain sagebrush-grassland habitat and associated wildlife species in the Northern Rockies. Sensitivity to climatic variability and change: A warmer climate will dry soils, reducing the forb component of mountain sagebrush-grassland habitat. Adaptation strategy/approach: Maintain current and restore historical habitat. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Manage fire to maintain desired habitat. Control invasive vegetation. Restore formerly cultivated land. Where can tactics be applied? (geographic) Range-wide Range-wide Range-wide Table 9.7—Adaptation options that address climate change effects on sagebrush habitat and associated wildlife species in the Northern Rockies. Sensitivity to climatic variability and change: A warmer climate and increased wildfire will reduce the distribution and abundance of sagebrush habitat. Adaptation strategy/approach: Maintain adequate sagebrush habitat. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Manage fire to maintain desired habitat. Control invasive vegetation. Restore formerly cultivated land. Prevent fragmentation of sagebrush habitat (roads, energy development lines). Where can tactics be applied? (geographic) Range-wide Range-wide Range-wide Range-wide

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 373 Table 9.8—Adaptation options that address knowledge gaps in climate change effects on wildlife populations in the Northern Rockies. Sensitivity to climatic variability and change: Species requirements and/or climate sensitivities are largely unknown for many species. Adaptation strategy/approach: Increase knowledge of species needs and climate sensitivities Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Analyze female lynx home ranges to determine necessary mix of habitat patches: distribution and size. Update and expand knowledge of existing pygmy distribution. Understand climate influences on pygmy rabbits. Understand succession after fire in sagebrush. Where can tactics be applied? (geographic) Range-wide Range-wide Range-wide Range-wide Sensitivity to climatic variability and change: Loss of connectivity can be caused by changes in water supply and snowpack dynamics, habitat loss, habitat shifts, vegetation phenology shifts, and human population expansion and redistribution. Adaptation strategy/approach: Maintain multiple levels of connectivity (daily, seasonal, dispersal range shift). Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Monitor connectivity using genetics, tracking, remote sensing tools (e.g., multi-carnivore genetic monitoring across the Northern Continental Divide Ecosystem with multiple partners. Compile table of connectivity vulnerability by species (daily through range shift). Identify dispersal habitat requirements for selected species (e.g., wolverine). Identify and remove or mitigate barriers. Sensitivity to climatic variability and change: Disease transmission may increase with warmer temperatures. Adaptation strategy/approach: Increase knowledge of disease-climate relationships. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Monitor environmental conditions at bat hibernacula to understand environmental conditions that promote white-nose syndrome. Monitor moose and bighorn sheep disease trends to determine if there are climatic drivers. Work with the State wildlife departments to monitor West Nile virus. Where can tactics be applied? (geographic) Region-wide Region-wide Region-wide

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
374 USDA Forest Service RMRS-GTR-374. 2018

Table 9.9—Adaptation options that address climate change effects on connectivity for wildlife populations in the Northern Rockies.

Sensitivity to climatic variability and change: Connectivity depends multiple factors, including water supply, habitat shifts, 

vegetation phenology, snow pack dynamics, and human population expansion and redistribution.

Adaptation strategy/approach: Maintain connectivity.

Specific tactic – A Specific tactic – B Specific tactic – C

Tactic Monitor connectivity through 

genetics, tracking, and remote 

sensing.

Compile table of known 

connectivity vulnerabilities by 

species.

Identify and remove barriers.

Where can tactics be 

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Appendix 9A—Adaptation Options for Wildlife in the 

Northern Rockies.

The following tables describe climate change sensitivities and adaptation strategies and tactics for wildlife, developed in 

a series of workshops as a part of the Northern Rockies Adaptation Partnership. Tables are organized by subregion within 

the Northern Rockies. See Chapter 9 for summary tables and discussion of adaptation options for wildlife.

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
382 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.1—Adaptation options that address climate change effects on wildlife in the Central Rockies subregion. Sensitivity to climatic variability and change: Potential conversion to grassland type; many ponderosa pine forests have converted to Douglas-fir types with fire exclusion and are therefore more susceptible to future fires (putting dry forest cavity nester habitat at risk). Adaptation strategy/approach: Restore fire-adapted ponderosa pine stand conditions for dry forest cavity nesters. Strategy objective: Promote resilience. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Reduce competition from Douglas-fir and grand fir (thin, burn) in current mature ponderosa pine stands. Conduct frequent understory burning. Retain current mature and older ponderosa pine stands and plant where it has been lost. Tactic effectiveness (risks) High High High Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Low elevations with emphasis on where compatible with wildland urban interface (WUI) objectives; need redundancy across the landscape to buffer against future fire or drought mortality Has to follow tactic A in the WUI, not necessarily in non-developed areas; need redundancy across the landscape to buffer against future fire or drought mortality Wherever they occur; need redundancy across the landscape to buffer against future fire or drought mortality Opportunities for implementation Collaboration with other landowners Collaboration with other landowners Collaboration with other landowners Cost Low in places with market size Douglas-fir, otherwise moderate. Moderate, depending on location Low for retaining, moderate for planting Barriers to implementation Some Major None

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 383 Table 9A.2—Adaptation options that address climate change effects on wildlife in the Central Rockies subregion. Sensitivity to climatic variability and change: Drying of inland maritime forest types that fishers depend on. Adaptation strategy/approach: Maintain current, restore historical, and promote potential future fisher habitat. Conserving fisher habitat preserves cool wet forest types that provide habitat for multiple other wildlife species. Strategy objective: Promote resilience, facilitate transition Specific tactic – A Specific tactic – B Specific tactic – C Tactic Conserve current old-growth cedar and larch, but reduce density to increase resilience to drought. Restore white pine with a cedar understory to create future habitat. Maintain or create necessary structure in modeled future fisher habitat. Tactic effectiveness (risks) Moderate Uncertain Unknown (will that be habitat) and uncertain (can the conditions be effectively created) Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Northern ID, Kootenai, Bitterroot divide; where risk of loss is greatest (edge of range); need redundancy across the landscape to buffer against future fire or drought mortality. Northern ID, Kootenai, Bitterroot divide; need redundancy across the landscape to buffer against future fire or drought mortality. Mission side of Swan; need redundancy across the landscape to buffer against future fire or drought mortality. Opportunities for implementation Fits with Collaborative Forest Landscape Restoration Program (CFLRP) objectives Fits with CFLRP objectives Fits with CFLRP objectives Cost Inexpensive Moderate Varies Barriers to implementation Major None Some

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
384 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.3—Adaptation options that address climate change effects on wildlife in the Central Rockies subregion. Sensitivity to climatic variability and change: Snow melt occurring earlier in the spring creates snowshoe hare pelage mismatch. Lynx adapted to deep soft snow and denser snow could give other predators a competitive advantage. Burn intensity is predicted to increase, and repeat burns can reduce tree seed source; in winter, lynx avoid high intensity burns until tree regeneration allows for branches at snow surface. Adaptation strategy/approach: Manage vegetation for long-term lynx and hare habitat and connectivity. Strategy objective: Promote resilience, reduce stressors, and facilitate transition. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Thin some young stands to create a variety of multi-storied hare habitat across the landscape to prevent boom and bust cycles. Maintain forest cover connections between good habitat patches. Maintain current multi-storied forest conditions, prevent large monoculture stand conditions (burning, harvest). Analyze female home ranges to determine necessary mix of habitat patches (distribution and size). Tactic effectiveness (risks) Uncertain Moderate Moderate Moderate Implementation urgency Near Term Near Term Near Term Near Term Where can tactics be applied? (geographic) Anywhere in current range of lynx Anywhere in current range of lynx Anywhere in current range of lynx Anywhere in current range of lynx Opportunities for implementation Forest Planning; U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service Northern Rockies Lynx Management Direction; critical habitat rule; U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service; Rocky Mountain Research Station; Collaborative Forest Landscape Restoration Program; Southwest Crown Partnership Cost Moderate Inexpensive Moderate Inexpensive Barriers to implementation Major Major None None

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 385 Table 9A.4—Adaptation options that address climate change effects on wildlife in the Central Rockies subregion. Sensitivity to climatic variability and change: Townsend’s big-eared bat maternal colonies winter hibernacula are sensitive to temperature change, loss of access to habitat, and spread of white-nose syndrome. Adaptation strategy/approach: Maintain maternal colony and hibernacula sites, and reduce non-climate stressors. Strategy objective: Increase knowledge, promote resilience, reduce stressors, engage coordination Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Identify, and protect current maternal colony sites. Monitor environmental conditions at identified sites, compared to unoccupied sites. Educate the public (caver groups) about spread of white- nose syndrome and stress decontamination procedures. Maintain, or create, open wetland complexes (for insects) near maternal colony sites. Tactic effectiveness (risks) High Moderate, but not an end point itself Moderate Unknown Implementation urgency Near term Near term Near term Near to mid term Where can tactics be applied? (geographic) Range wide Public land Range wide Public land Opportunities for implementation Local caving clubs Local caving clubs Local caving clubs Mostly on private lands Cost Moderate Inexpensive Inexpensive Variable Barriers to implementation Some Some None Some

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
386 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.5—Adaptation options that address climate change effects on wildlife in the Central Rockies subregion. Sensitivity to climatic variability and change: Increasing winter temperatures reduce snowpack, and snow melt occurs earlier in the spring. Wolverines are obligate snow denners. Adaptation strategy/approach: Maintain wolverine female reproductive capacity and core habitat connection. Strategy objective: Reduce stressors. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Map areas with high persistent snow potential; identify protection status and development potential to identify areas of concern and connection between mountain ranges. Identify dispersal habitat requirements. Conduct multi-carnivore genetic monitoring. Tactic effectiveness (risks) High Variable High Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Range wide Range wide Range wide Opportunities for implementation Coordinate existing monitoring, and develop regional monitoring goals. Cost Inexpensive Expensive Expensive Barriers to implementation None Some Some

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 387 Table 9A.6—Adaptation options that address climate change effects on wildlife in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Pygmy rabbits are dependent on big-sage, which may be vulnerable to climate change, but range could expand with climate change. Adaptation strategy/approach: Increase information on distribution and sensitivities of pygmy rabbit. Strategy objective: Increase knowledge. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Produce more accurate sage distribution layer. Update and expand knowledge of existing pygmy distribution. Understand climate influences on pygmy rabbits. Tactic effectiveness (risks) Moderate Moderate Moderate Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Eastern subregion Eastern subregion Eastern subregion Opportunities for implementation Heritage program. Wildlife Conservation Society study at the Idaho National Lab; candidate for State Wildlife Grant funding Cost Moderate Moderate Moderate Barriers to implementation Some: funding priority Some: funding priority Some: funding priority, not on anyone’s radar screen

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
388 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.7—Adaptation options that address climate change effects on wildlife in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Pygmy rabbits are dependent on big-sage, which may be vulnerable to climate change, but range could expand with climate change. Adaptation strategy/approach: Conserve pygmy rabbit habitat. Strategy objective: Promote resilience. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Obtain conservation easements in current sagebrush areas. Lease sagebrush. Understand succession after fire in sagebrush in the region. Tactic effectiveness (risks) High High High Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Sagebrush habitat on unprotected private land Sagebrush habitat on private and State land Sagebrush habitat Opportunities for implementation Land Reliance; partners Cost Inexpensive (cost-sharing and is happening now, even though a lot of money is spent) Inexpensive (happening now, even though a lot of money is spent) Inexpensive to moderate Barriers to implementation Some: land owner willingness; political consequences Some Funding priorities; lack of understanding for the need for the information; difference of opinion about what we already know

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 389 Table 9A.8—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Bat hibernaculum temperature change linked to white-nose syndrome; alternative energy development impacts (wind power). Adaptation strategy/approach: Maintain healthy bat populations. Strategy objective: Reduce stressors; increase knowledge and coordination. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Consider summer roosting in vegetation management. Protect hibernacula from disturbance. Survey for hibernacula. Tactic effectiveness (risks) Uncertain Moderate Uncertain Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
390 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.9—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Reduced stream flow, loss of riparian vegetation, incised stream channels due to flood events. Adaptation strategy/approach: Maintain healthy beaver populations on the landscape. Strategy objective: Promote resilience; reduce stressors; increase public knowledge (slow down the water). Specific tactic – A Specific tactic – B Specific tactic – C Tactic Inventory current and potential habitat (include multiple factors). Restore riparian habitat (e.g., plant willows, manage grazers, raise water level). Translocate beavers, manage trapping. Tactic effectiveness (risks) High High High Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 391 Table 9A.10—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Habitat shifts and disease transmission in bighorn sheep from direct and indirect effects of climate change (e.g., increase in overlap with domestics, increased disease transmission, shifts in pressure from recreation). Adaptation strategy/approach: Maintain healthy bighorn sheep populations. Strategy objective: Increase knowledge; reduce stressors; promote resilience. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Monitor sheep disease trends to determine if there are climate drivers. Identify locations and improve connectivity between seasonal ranges; maintain separation from domestic sheep. Maintain communication among research groups and promote sharing of information and collaboration of research/management efforts. Tactic effectiveness (risks) Unknown High Moderate Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Focus of current attention (state, federal, non-governmental organizations, universities) Focus of current attention (state, federal, non- governmental organizations, universities) Focus of current attention (state, federal, non-governmental organizations, universities) Cost Inexpensive Moderately to expensive depending on scale Inexpensive Barriers to implementation None Some to major (social, legal, jurisdiction) None

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
392 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.11—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Loss of mountain sage and grassland habitat for Brewer’s sparrow. Adaptation strategy/approach: Maintain adequate mountain sage grassland communities for Brewer’s sparrow. Strategy objective: Promote resilience, reduce stressors, and increase knowledge. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Manage fire to maintain desired habitat (see sage-grouse conservation strategy). Control invasive vegetation. Restore formerly cultivated land. Tactic effectiveness (risks) High Low to high depending on the invasive species Low to high depending on site conditions Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 393 Table 9A.12—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Water supply; habitat loss; habitat shifts; vegetation phenology shifts; human population expansion and redistribution; snowpack dynamics. Adaptation strategy/approach: Maintain connectivity within and through the Greater Yellowstone Area (GYA), including daily, seasonal, dispersal, and range shift connectivity. Strategy objective: Facilitate transition; engage coordination; increase knowledge Specific tactic – A Specific tactic – B Specific tactic – C Tactic Monitor connectivity (genetics, tracking, remote sensing). Compile table of connectivity (daily through range shift) vulnerability by species. Identify and remove barriers. Tactic effectiveness (risks) Moderate High High Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation New technologies (e.g., eDNA, remote cameras, GPS collars) make this more accessible Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
394 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.13—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Moose prefer colder temperatures; increased disease potential in warmer climates; increased algal growth in warmer ponds; precipitation patterns affect growth of preferred vegetation. Adaptation strategy/approach: Maintain healthy moose habitats (e.g., riparian, aspen, spruce-fir) and populations. Strategy objective: Reduce stressors; engage coordination. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Reduce mortality; coordinate with state agencies to reduce hunting quotas; coordinate to reduce highway mortality. Increase knowledge and monitoring of disease and pests. Improve riparian habitat: see beaver sheet. Tactic effectiveness (risks) Moderate Moderate High Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 395 Table 9A.14—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Loss of aspen due to warmer, drier climate and lower water table. Adaptation strategy/approach: Maintain adequate habitat structural diversity to support ruffed grouse populations. Strategy objective: Promote resilience; increase knowledge. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Promote disturbance (fire, cutting) in older aspen stands. Protect from grazing (fencing, manage grazing). Reduce conifer competition (fire, cutting) in any age aspen stand. Tactic effectiveness (risks) High High High Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
396 USDA Forest Service RMRS-GTR-374. 2018 Table 9A.15—Adaptation options that address climate change effects on wildlife in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Loss of sage and grassland habitat for greater sage-grouse. Adaptation strategy/approach: Maintain adequate sage grassland communities, with inclusion of mesic meadows (brood rearing), for greater sage grouse. Strategy objective: Promote resilience, reduce stressors, increase knowledge Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Manage fire to maintain desired habitat (see sage-grouse conservation strategy). Control invasive vegetation. Restore formerly cultivated land. Limit human disturbance (e.g., grazing, hunting, infrastructure). Tactic effectiveness (risks) High Low to High depending on the invasive species Low to high depending on site conditions High Implementation urgency Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 397 Table 9A.16—Adaptation options that address climate change effects on wildlife in the Western Rockies subregion. Sensitivity to climatic variability and change: Conversion to nonnatives; change in fire frequency; reduction in cover; change of available forage could affect insects, affecting mountain quail habitat. Adaptation strategy/approach: Reduce stressors on mountain quail. Strategy objective: Promote resilience, reduce stressors Specific tactic – A Specific tactic – B Specific tactic – C Tactic Reduce high-intensity burns using fuel breaks and late winter burning to reduce fuel buildup. Maintain conifer components, including north face and higher elevation riparian stringers to retain moisture in microsites; replant; protect from burning; avoid harvesting. Need more information on insect production and the forb component associated with moist areas; how will insects react with phenology changes? Tactic effectiveness (risks) Implementation urgency Where can tactics be applied? (geographic) Western Rockies subregion Western Rockies subregion Western Rockies subregion Opportunities for implementation Cost Barriers to implementation

Chapter 9: Climate Change and Wildlife in the Northern Rockies Region
398 USDA Forest Service RMRS-GTR-374. 2018

Introduction

Outdoor recreation is an important benefit provided by 

Federally managed and other public lands throughout the 

Rocky Mountains. National forests in the Forest Service, 

U.S. Department of Agriculture (USFS) Northern Region 

and Greater Yellowstone Area (a region hereafter called 

the Northern Rockies region) have an estimated 13.3 million visits per year; Yellowstone, Grand Teton, and Glacier 

National Parks account for another 8 million visits per 

year. National forests and national parks provide recreation 

opportunities at sites that offer a wide variety of characteristics. Recreation on public lands in the Northern Rockies 

region is inseparable from ecosystems and natural features. 

Whether visitors ski, hike, hunt, or camp, explore developed 

sites or the backcountry, or simply drive through a park or 

forest, natural and ecological conditions in large part determine their overall recreation experience.

Climatic conditions and environmental characteristics that depend on climate are key factors that determine 

the availability of and demand for different recreation 

opportunities (Shaw and Loomis 2008). Changing climatic conditions may alter the supply of and demand for 

recreation opportunities, resulting in changes in visitation 

patterns and the benefits derived from recreation in the 

future. Climate change is projected to increase outdoor 

recreation participation in general (Bowker et al. 2014). 

Benefits provided by recreation are expected to increase under climate change scenarios because anticipated increases 

in summer and warm-weather activities will outweigh losses 

in winter activities (Loomis and Crespi 2004; Mendelsohn 

and Markowski 2004).

Public lands managers will face a complex task of managing recreation opportunities under changing recreational 

preferences and ecological conditions. Investments in infrastructure, the provision and maintenance of facilities, and 

decisions about recreation development are important inputs 

that determine recreational setting and the type of recreational opportunities available to visitors. These inputs can 

be classified by using the Recreation Opportunity Spectrum, 

which has been used for decades by public lands managers for planning and allocation of recreation opportunities 

(Clark and Stankey 1979). Recreation visitation behavior 

and values can be mapped to the Recreation Opportunity 

Spectrum, providing managers with information about the 

tradeoffs associated with different types of investments and 

development (Rosenthal and Walsh 1986; Swanson and 

Loomis 1996). A changing climate may alter types of recreation experiences desired and the opportunities that can be 

provided by public lands.

Although broad trends in recreation participation under 

climate change scenarios may be borne out at the regional 

scale, little is known about how recreation in the Northern 

Rockies region will change. This chapter describes the 

broad categories of recreation activities that may be sensitive to climate-related changes in the region, and assesses 

the likely effects of projected climate changes on recreation 

participation.

Relationships Between Climate 

Change and Recreation

The supply of and demand for recreation opportunities 

are sensitive to climate through (1) a direct effect of changes 

in temperature and precipitation on the availability and quality of recreation sites, and (2) an indirect effect of climate 

on the characteristics and ecological condition of recreation 

sites (Loomis and Crespi 2004; Mendelsohn and Markowski 

2004; Shaw and Loomis 2008) (fig. 10.1).

Direct effects of changes in temperature and precipitation patterns are likely to affect most outdoor recreation 

activities in some way. Direct effects are important for 

skiing and other snow-based winter activities that depend on 

seasonal temperatures and the amount, timing, and phase of 

precipitation (Englin and Moeltner 2004; Irland et al. 2001; 

Stratus Consulting 2009). Warm-weather activities are also 

sensitive to direct effects of climate change. Increases in 

minimum temperatures have been associated with increased 

national park visits in Canada, particularly during nonpeak 

“shoulder” seasons (Scott et al. 2007). The number of 

projected warm weather days is positively associated with 

expected visitation for a national park in the United States, 

although visitation is expected to be lower under extremeheat scenarios (Bowker et al. 2012; Richardson and Loomis 

2004). Temperature and precipitation may also directly affect the comfort and enjoyment that participants derive from 

engaging in an activity on a given day (Mendelsohn and 

Markowski 2004).

Indirect climate effects tend to be important for recreation activities that depend on additional ecosystem 

inputs, such as wildlife, vegetation, and surface water. 

Chapter 10: Effects of Climate Change on 

Recreation in the Northern Rockies Region

Michael S. Hand and Megan Lawson
USDA Forest Service RMRS-GTR-374. 2018 399

Cold-water fishing is expected to decline in the future 

due to climate effects on temperature and streamflow that 

threaten cold-water fish species habitat (Jones et al. 2013) 

(see Chapter 5). Surface water area and streamflows are 

important for water-based recreation (e.g., boating), and 

forested area affects several outdoor activities (e.g., camping and hiking) (Loomis and Crespi 2004). Recreation 

visits to sites with highly valued natural characteristics, 

such as glaciers or popular wildlife species (see chapters 4 

and 9) or scenic and aesthetic qualities, may be reduced in 

some future climate scenarios if the quality of those characteristics is threatened (Scott et al. 2007). The indirect 

climate effect on disturbances, and wildfire in particular 

(see Chapter 8), may also play a role in recreation behavior, although the effect may be diverse and vary over time 

(Englin et al. 2001).

Identifying Climate-Sensitive 

Outdoor Recreation Activities

People participate in a wide variety of outdoor recreation 

activities in the Northern Rockies region. The National 

Visitor Use Monitoring (NVUM) survey, conducted by the 

USFS to monitor recreation visitation and activity on national forests, identifies 27 different recreation activities in 

which visitors may participate. These include a wide variety 

of activities and ways that people enjoy and use national 

forests and other public lands.

The NVUM surveys roughly one-quarter of forest units 

in each region every year, and each unit is surveyed again 

every 5 years. For this analysis, we used the latest survey 

data available for each forest. Sample years for the units 

included in this analysis are as follows: 2008—Bridger-Teton, 

Custer, Helena; 2009—Gallatin, Idaho Panhandle, Shoshone; 

2010—Beaverhead-Deerlodge, Caribou-Targhee, Flathead; 

Figure 10.1—Direct and indirect effects of climate on recreation decisions.

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
400 USDA Forest Service RMRS-GTR-374. 2018

2011—Clearwater, Lolo, Nez Perce; 2012—Bitterroot, 

Kootenai, Lewis and Clark. Visitors are sampled by using a 

stratified random sampling technique designed for assessing 

use on national forests. Sampling sites are stratified according 

to type of recreation site and times of day and week. Visitors 

are asked about different categories of trip-related spending incurred within 50 miles of the site where they are interviewed. 

Interviewees are selected at random, and interviewers conduct 

as many surveys as possible (English et al. 2001).

All outdoor recreation activities depend to some degree, 

directly or indirectly, on climatic conditions or environmental 

conditions that are determined by climate. For example, 

skiing opportunities depend on the availability of areas with 

snow-covered terrain, which is determined by patterns of temperature and precipitation as snow. As climate change affects 

seasonal trends in temperature and precipitation, the availability of certain skiing sites may change in the future.

To assess how recreation patterns may change in the 

Northern Rockies region, categories of outdoor recreation 

activities that may be sensitive to climate changes were identified (fig. 10.2). For this assessment, a recreation activity was 

considered sensitive to climate change if changes in climate 

or environmental conditions that depend on climate would be 

an important factor affecting the demand for or supply of that 

recreation activity within the study area. However, there is no 

hard rule by which activities satisfy this requirement, and other 

types of activities not explicitly covered in this chapter may be 

affected by climate changes.

The 27 recreation activities identified in the NVUM survey 

were grouped into 5 climate-sensitive categories of activities, 

plus an “Other” category of activities that are less sensitive to 

climate changes. Each category includes activities likely to be 

affected by changes in climate and environmental conditions 

in similar ways. Table 10.1 lists the activities in the climatesensitive categories and summarizes their sensitivity to climate 

changes. The categories were developed to capture the most 

common types of recreation that people engage in on public 

lands in the Northern Rockies region that would be affected by 

climate changes. Seventeen activities were identified as sensitive to climate changes.

These 17 activities account for the primary recreation 

activities for 83 percent of visits to national forests in the study 

area. Activities in the “Other” category were judged to be less 

sensitive to climate changes and tend to be less frequently 

listed as a primary recreation activity in the Northern Rockies 

region. Although participation in many of these activities may 

be linked to climate in some way, other factors are likely to 

be more important determinants of participation (for example, 

maintenance of infrastructure for visiting interpretive sites). 

Warm-weather activities are the most popular, and include 

hiking/walking, viewing natural features, developed and 

primitive camping, bicycling, backpacking, horseback riding, 

picnicking, and other nonmotorized uses. These were the 

main activity for 35.9 percent of national forest visitors (4.8 

million visitors per year) (table 10.1). Of these, hiking/walking 

was the most popular, and is the primary reason for a visit 

for 16.9 percent of visitors (2.2 million people). Snow-based 

winter activities are also a large draw, and include downhill 

skiing, snowmobiling, and cross-country skiing. They were 

the primary activity for 25.0 percent of all visitors (3.3 million 

people). Wildlife-related activities, including hunting, fishing, 

and viewing wildlife, were the primary activity for 18.5 percent of visitors (2.5 million people). Of these, hunting was the 

most popular with 11 percent of visitors (1.5 million people). 

Gathering forest products such as berries and mushrooms 

was the primary activity for 2.4 percent of visitors (300,000 

people). Motorized and nonmotorized water activities (other 

than fishing) attracted 0.7 percent of visitors (97,000 people) 

(table 10.1).

Non-local visitors—those who report a home ZIP code that 

is more than 30 miles from the forest boundary—spend $601 

million (in 2014 dollars) per year within 50 miles of the forest 

boundaries. Note that some nonlocal respondents may have 

second homes near the forest boundary that would qualify 

as local had they reported the ZIP code associated with the 

second home (Stynes and White 2005). Table 10.2 summarizes 

expenditures by visitors to national forests in the Northern 

Rockies region. We focus on spending by nonlocal visitors 

because their expenditures in local communities would not 

have occurred otherwise. Lodging expenses account for nearly 

31 percent of total expenditures, followed by restaurants (18 

percent), gas and oil (17 percent), and groceries (12 percent). 

The remaining expenditure categories of other transportation, 

activities, admissions and fees, and souvenirs represent 21 

percent of all spending.

Climate Change Vulnerability 

Assessment

The overall effect of climate change on recreation activity is likely to be an increase in participation and increase in 

the benefits derived from recreation. This is due primarily to 

warmer temperatures and increased season length appropriate Figure 10.2—Percent of total national forest visits by climatesensitive primary activity.

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 401

Table 10.1—Participation in different recreational activities in national forests in the Northern Region and Greater Yellowstone 

Area.

Activity Relationship to climate and environmental conditions

National Forest visitors who 

participated in this activity as 

their main activitya

Percent of total 

NF visits Number

Warm-weather activities Participation typically occurs during warm weather; 

dependent on the availability of snow- and ice-free sites, 

dry weather with moderate daytime temperatures, and 

the availability of sites where air quality is not impaired 

by smoke from wildfires.

35.9 4,770,616

Hiking/walking 16.9 2,248,171

Viewing natural features 8.6 1,136,245

Developed camping 2.8 375,174

Bicycling 2.2 286,707

Other non-motorized 2.0 265,476

Horseback riding 1.3 168,175

Picnicking 1.2 164,638

Primitive camping 0.6 74,876

Backpacking 0.4 51,154

Winter activities Participation depends on the timing and amount of 

precipitation as snow and cold temperatures to support 

consistent snow coverage. Inherently sensitive to climate 

variability and inter-annual weather patterns.

25.0 3,318,426

Downhill skiing 12.8 1,695,621

Snowmobiling 6.4 843,778

Cross-country skiing 5.9 779,027

Wildlife activities Wildlife availability is a significant input for these 

activities. Temperature and precipitation are related 

to habitat suitability through effects on vegetation, 

productivity of food sources, species interactions, and 

water quantity and temperature (for aquatic species). 

Disturbances (wildland fire, invasive species, insect and 

disease outbreaks) may affect amount, distribution, and 

spatial heterogeneity of suitable habitat.

18.5 2,452,053

Hunting 11.3 1,503,520

Fishing 5.3 708,589

Viewing wildlife

1.8 240,944

Gathering forest products Depends on availability and abundance of target 

species (e.g., berries, mushrooms), which are related to 

patterns of temperature, precipitation, and snowpack. 

Disturbances may alter availability and productivity 

of target species in current locations and affect 

opportunities for species dispersal.

2.4 313,475

Water-based activities, not 

including fishing

Participation requires sufficient water flows (in streams 

and rivers) or levels (in lakes and reservoirs). Typically 

considered a warm-weather activity, and depends on 

moderate temperatures and snow- and ice-free sites. 

Some participants may seek water-based activities as a 

heat refuge during periods of extreme heat.

0.7 96,643

a Source: USDA FS (n.d.). Total estimated National Forest visits is 13,273,685. Percentage calculations are based on the percent of total visits 

accounted for by each activity and category.

for warm-weather activities, outweighing decreased winter 

activities that depend on snow and consistently cold temperatures (Mendelsohn and Markowski 2004). However, these 

general findings mask potential variation in the effects of climate on recreation between types of activities and geographic 

locations (boxes 10.1, 10.2).

This section assesses the likely effects of climate on major 

climate-sensitive recreation activities in the region (table 10.3). 

Two sources of information are used to develop assessments 

for each category of recreation activity. First, reviews of existing studies of climate change effects on recreation and studies 

of how recreation behavior responds to climate-sensitive 

ecological characteristics are used to draw inferences about 

likely changes for each activity category. Second, projections 

of ecological changes specific to the Northern Rockies region, 

as detailed in the other chapters of this volume, are paired with 

the recreation literature to link expected responses of recreation behavior to specific expected climate effects.

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
402 USDA Forest Service RMRS-GTR-374. 2018

Table 10.2—Total annual expenditures by non-local and local visitors to Northern Rockies and Greater Yellowstone 

Area national forests, by spending category.

Non-local spending,a,b Local spending

Spending category Total annual 

expenditures 

Spending for 

each category

Total annual 

expenditures 

Spending for 

each category

Lodging

Thousands of $ (2014)

185,355 

%

31

Thousands of $ (2014)

 14,743 

%

6

Restaurant 109,743 18 29,618 13

Groceries 74,003 12 44,886 19

Gasoline, oil 104,319 17 78,880 34

Other transportation 3,013 1 1,059 0

Activities 36,376 6 14,195 6

Admissions, fees 39,482 7 19,103 8

Souvenirs 48,839 8 28,075 12

Total 601,128 230,562 

a Non-local refers to trips that required traveling more than 50 miles.

b Source: USDA FS (n.d.).

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Current Conditions and Existing Stressors

Public lands in the Northern Rockies region provide 

an abundance and variety of recreational options, offering opportunities for people of all interests and abilities. 

Opportunities range from high-use developed sites near 

urban areas and popular tourist destinations, to vast areas 

of remote wilderness and seldom used sites off the beaten 

path. The facilities and services available also exhibit a 

wide range of conditions and characteristics. Some sites are 

developed with modern amenities and staffed by agency employees or volunteers. Others may exhibit scant evidence of 

human influence other than a trailhead.

Current conditions reflect wide variation in intra-annual 

and interannual (within and between years) weather and 

ecological conditions. Temperature, precipitation, water 

flows and levels, wildlife distributions, vegetative conditions, and wildfire activity may vary widely. Recreationists 

are most likely already accustomed to some degree to making decisions with a significant degree of uncertainty about 

conditions at the time of participation.

Several existing challenges and stressors affect recreation 

in the Northern Rockies region. Increased population, 

particularly in proximity to public lands, can strain visitor services and facilities due to increased use; projected 

population increases in the future may exacerbate these effects (Bowker et al. 2012). Increased use due to population 

growth can also reduce site quality because of congestion at 

the most popular sites (Yen and Adamowicz 1994). Changes 

in land use may alter access to public lands, fragmentation 

of landscapes and habitat, and disturbance regimes that 

relate to recreation activities.

The physical condition of recreation sites and natural 

resources is constantly changing due to human and natural 

forces. Recreation sites and physical assets need maintenance, and deferred or neglected maintenance may increase 

congestion at other sites that are less affected or increase 

hazards for visitors who continue to use degraded sites. 

Unmanaged recreation can create hazards and contribute 

to natural resource degradation (USDA FS 2010). This 

stressor may interact with others, such as population growth 

and maintenance needs, if degraded site quality or congestion encourages users to engage in recreation that is not 

supported or appropriate at certain sites or at certain times 

of the year. Natural hazards and disturbances may create 

challenges for the provision of recreation opportunities. For 

example, wildfire affects recreation demand (due to site 

quality and characteristics), but may also damage physical 

assets or exacerbate other natural hazards such as erosion 

(see chapters 4 and 12).

Current Management

Recreation is an important component of public land 

management in the Northern Rockies region. For lands managed by the USFS, sustainable recreation serves as a guiding 

principle for planning and management purposes (USDA 

FS 2010, 2012b). Recreation is included with other major 

multiple uses of national forests, such as timber products and 

livestock grazing. Sustainable recreation seeks to sustain and 

expand the benefits to the United States that quality recreation opportunities provide (USDA FS 2010). At the heart of 

this principle is the desire to manage recreational resources 

to increasingly connect people with natural resources and 

cultural heritage, and adapt to changing social needs and 

environmental conditions. Recreation managers aim to provide diverse recreation opportunities that span the recreation 
USDA Forest Service RMRS-GTR-374. 2018 403

Box 10.1—Subregional Assessment of Climate Change Effects on Recreation

The broad links between climate, ecological changes, and recreation behavior that form the basis of the activity 

category assessments are designed to be generally applicable to all locations in the Northern Rockies region. However, 

in a region that encompasses parts of five States and stretches hundreds of miles from east to west, significant 

subregional heterogeneity in climate effects may exist. The five Northern Rockies Adaptation Partnership (NRAP) 

subregions (Western Rockies, Central Rockies, Eastern Rockies, Greater Yellowstone Area [GYA], Grassland) 

represent a wide variety of geographic and ecological features, and each has distinctive recreation opportunities that 

may be sensitive to climate changes. Assessing differences between the subregions can yield more geographically 

specific information about the effects of climate on recreation.

Table 10.B1 summarizes national forest visits by primary activity category for each subregion. Warm-weather activities 

are the most common category for all subregions, but there are significant differences in the relative importance of 

each activity category. Snow-based recreation is relatively more important in the Central Rockies, Eastern Rockies, 

and GYA subregions, where there are multiple sites with consistently viable snow seasons and developed ski areas. 

In contrast, much less snow-based recreation (as a share of total visits) occurs in the Western Rockies and Grassland 

subregions. Wildlife recreation activities (hunting, fishing, wildlife viewing) are most important in the Western Rockies 

and Grassland, although the Central Rockies, Eastern Rockies, and GYA see a significant minority of visitors engaging 

in these activities. Forest product gathering and water-based (not fishing) activities represent a small share of visits in 

all subregions, but the Grassland subregion sees almost no visitation for these activities.

The differences in activity participation also suggest that climate will have different effects on recreation in each 

subregion. The largest differences in activity participation are for snow-based activities; these activities are also the 

most likely to have negative impacts due to warming temperatures and decreased precipitation as snow. The Grassland 

subregion and to a lesser extent the Western Rockies have relatively low exposure to this effect because snow-based 

recreation is less prominent. The Central Rockies, Eastern Rockies, and GYA have higher participation in snowbased activities that could be exposed to climate change, although it is unclear to what extent snow-based sites will 

experience changes that degrade conditions for snow-based activities. 

Other differences between subregions are likely to depend on differences in climate effects between subregions. For 

example, one subregion could experience warming that increases the incidence of extreme heat days, which has a 

negative impact on warm-weather recreation, whereas another subregion might experience warming that extends the 

warm-weather season without a significant increase in the incidence of extreme heat days. 

Table 10.B1—National Forest visits by NRAP subregion and activity category.

Subregiona

Activity category

Western 

Rockies

Central 

Rockies

Eastern 

Rockies Grassland

Greater 

Yellowstone 

Area

Percent of annual visitors reporting main activity

Warm-weather activitiesb,c 36.7 36.9 33.3 60.8 36.2

Snow-based winter activities 7.4 26.0 27.2 1.6 31.3

Wildlife activities 23.3 19.6 18.8 30.5 15.1

Forest product gathering 6.5 1.9 2.1 0.0 1.1

Water-based activities, not including 

fishing

0.5 0.8 1.6 0.2 0.1

a To estimate activity participation, subregions are defined by groups of national forests: Western Rockies (Idaho Panhandle, 

Kootenai, Nez Perce-Clearwater), Central Rockies (Bitterroot, Flathead, Lolo), Eastern Rockies (Beaverhead-Deerlodge, Custer, 

Gallatin, Helena, Lewis and Clark), Grassland (Dakota Prairie Grasslands), Greater Yellowstone Area (Bridger-Teton, CaribouTarghee, Shoshone). Geospatial definitions of the subregions include parts of several forests divided between two subregions—

for example, parts of Custer, Beaverhead-Deerlodge, and Gallatin National Forests are divided between the Eastern Rockies 

and Greater Yellowstone Area subregions, but tabulated as part of the Eastern Rockies subregion; these forests are also 

summarized in table 10.B2 separately from the other Greater Yellowstone Area forests.

b Source: USDA FS (n.d.).

c Percentages do not sum to 100 because not all visitors report activities, and not all activities are included in climate-sensitive 

categories (e.g., nature center activities, visiting historic sites).

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
404 USDA Forest Service RMRS-GTR-374. 2018

Box 10.2—Climate Change in the Greater Yellowstone Area and Glacier National Park

The Greater Yellowstone Area (GYA) provides a wide range of recreation opportunities. The GYA is composed of two 

national parks (Yellowstone, Grand Teton), parts of six national forests (Beaverhead-Deerlodge, Bridger-Teton, CaribouTarghee, Custer, Gallatin, Shoshone), and other Federally administered protected areas (John D. Rockefeller Memorial 

Parkway, National Elk Refuge, Red Rock Lakes National Wildlife Reserve). These areas offer the full spectrum of 

recreation opportunities, from developed and urban settings to wilderness and primitive sites. Glacier National Park, 

which straddles the Western and Eastern Rockies subregions in northwestern Montana, also provides a broad range of 

recreation opportunities comparable to those in the GYA.

Recreation visitation to Federal units within the GYA and Glacier National Park is summarized in table 10.B2. 

Yellowstone National Park and Grand Teton National Park receive an annual average of 3.4 million and 2.6 million 

visitors, respectively. For both parks, two of the most common activities were viewing wildlife and viewing scenery and 

natural features. Most Yellowstone visitors also indicated that they engaged in developed camping, walking or hiking, 

and visiting museums and visitor centers. Grand Teton visitors indicated pleasure driving and walking or hiking as 

common activities (NPS 2006). Wildlife viewing is also an important activity for visitors to the Red Rock Lakes National 

Wildlife Refuge and the National Elk Refuge, although these sites receive only a fraction of the visitors compared with 

the national parks (NPS 2006). Sightseeing is the dominant activity for the 2.1 million annual visitors in Glacier National 

Park.

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Table 10.B2—Recreation visits to Greater Yellowstone Area units and Glacier National Park.

Unit Total annual visits Most frequent activity Year

Yellowstone National Parka,b 3,390,000 Viewing wildlife 

(93% of visitors)

2010–2014 annual average

Grand Teton National 

Parka,b

2,650,000 Viewing scenery 

(88% of visitors)

2010–2014 annual average

Red Rock Lakes National 

Wildlife Reservec

12,000 Viewing wildlife 

(45% of visitors)

2014

National Elk Refugea,d 900,000 Viewing wildlife 

(53% of visitors)

2008, 2004

Gallatin National Foreste 2,010,000 Hiking/walking

(29% of visitors)

2009

Beaverhead-Deerlodge 

National Foreste

583,000 Hunting

(32% of visitors)

2010

Caribou-Targhee National 

Foreste

1,850,000 Hiking/walking 

(18% of visitors)

2010

Shoshone National Foreste 646,000 Viewing natural 

features

(25% of visitors)

2009

Bridger-Teton National 

Foreste

2,180,000 Downhill skiing 

(31% of visitors)

2008

Custer National Foreste 314,000 Downhill skiing 

(26% of visitors)

2008

Glacier National Parkb,f 2,149,000 Sightseeing 

(97% of visitors)

2010–2014 annual average

1990 (visitor activities)

a Source: NPS (2006).

b Source: NPS (2014).

c Source: USDI (2014).

d Source: Sexton et al. (2012). 

e Source: USDA FS (n.d.); most frequent activity is the reported main activity (visitors may engage in other secondary or tertiary 

activities).

f

 Source: Littlejohn (1991).

Note: Visitor data are not available for John D. Rockefeller Parkway.
USDA Forest Service RMRS-GTR-374. 2018 405

Box 10.2—Continued.

National forests in the GYA receive a combined 7.6 million visitors annually. The most popular activity for visitors varies 

across forests. In the Gallatin and Caribou-Targhee National Forests, hiking and walking are the most popular activities, 

whereas downhill skiing is the most popular activity in Bridger-Teton and Custer National Forests. In BeaverheadDeerlodge National Forest, hunting is the most popular activity (32 percent of visitors) and in Shoshone National Forest, 

viewing natural features is the most popular activity (25 percent of visitors).

Most of the general assessment of climate change effects on recreation in the Northern Rockies applies to the GYA and 

Glacier National Park, although the different activity profile means that exposure to the effects of climate change differs 

in this subregion. Visitation is dominated by warm-weather visits; 80 percent of visits to Yellowstone and Grand Teton 

National Parks are during the June–September period. An additional 11 percent of visits occur during the “shoulder” 

season months of May and October. Warmer temperatures are expected to increase warm-weather recreation; earlierand later-season periods of snow- and ice-free sites in the parks may encourage additional off-peak visitation. Some 

visitors may also substitute early- or late-season visits to avoid extreme summer heat. However, seasonal shifts in 

visitation may be constrained by summer vacation months determined by academic calendars. 

Changes in the distribution and abundance of wildlife may affect recreation visitation and enjoyment for the large 

number of Yellowstone and Grand Teton visitors who engage in wildlife viewing. However, many climate-related 

changes in target wildlife species are ambiguous because of complex interactions between species, vegetation and 

forage opportunities, and disturbances (see Chapter 9). 

Other popular activities, such as driving for pleasure on roads and viewing scenery and special features (e.g., geysers 

and thermal features in Yellowstone, driving the Going-to-the-Sun Road in Glacier National Park), may be more or 

less sensitive to climate changes. In some cases the qualities, characteristics, and features that draw visitors to 

these activities have a limited connection to climate changes. However, features such as glaciers and snow-capped 

mountains are a particular draw for some visitors, and visitation tied to such features is likely to be affected. Longer 

warm-weather seasons will probably increase access to roads and sites inaccessible when snow and ice are present; 

greater accessibility would have a positive effect on visitation. In addition, wildfire and other disturbances can affect 

site access and the desirability of visiting fire-affected sites. For example, wildfires in Yellowstone National Park are 

associated with decreased visitation in the subsequent month, but there does not appear to be a lasting negative effect 

on visitation or wildfire occurrence (Duffield et al. 2013).

opportunity spectrum, from modern and developed to primitive and undeveloped (Clark and Stankey 1979).

Warm-Weather Activities

Warm-weather activities as a category are the most common recreation activities in national forests and national 

parks in the Northern Rockies region. Slightly more than 

one-third of all visits involve one of these activities as the 

primary activity of visitors. Warm-weather recreation is sensitive to the length of appropriate season, depending on the 

availability of snow- and ice-free trails and sites, and the timing and number of days with temperatures within the range 

of comfortable temperatures (which may vary with activity 

type and site). The number of warm-weather days has been 

shown to be a significant predictor of visitation behavior 

(Richardson and Loomis 2004), and studies of national park 

visitation show that minimum temperature is a strong predictor of monthly visitation patterns (Scott et al. 2007).

Participants are also sensitive to site quality and characteristics, such as the presence and abundance of wildflowers, 

condition of trails, and vegetation and cover (e.g., cover for 

shade, wildfire effects). The condition of unique features 

that are sensitive to climate changes, such as glaciers, may 

affect the desirability of certain sites (Scott et al. 2007). 

Forested area is positively associated with warm-weather 

activities, such as camping, backpacking, hiking, and 

picnicking (Loomis and Crespi 2004), and is sensitive to 

future climate changes (USDA FS 2012a).

Wildfire can also affect participation in warm-weather 

activities through changes to site quality and characteristics 

(fig. 10.3). Wildfires have a diverse and temporally nonlinear 

effect on recreation (Englin et al. 2001). The presence of 

recent wildfires has differential effects on the value of hiking 

trips (positive) and mountain biking (negative), although 

recent wildfire activity tends to decrease the number of 

visits (Hesseln et al. 2003, 2004; Loomis et al. 2001). The 

severity of fire may also matter; high-severity fires have 

been associated with decreased recreation visitation, whereas 

low-intensity fires are associated with slight increases in visitation (Starbuck et al. 2006). Recent fires are associated with 

initial losses of benefits for camping (Rausch et al. 2010) and 

backcountry recreation activities (Englin et al. 1996); these 

effects are attenuated over time. Visitation in Yellowstone 

National Park tends to be lower following months with high 

wildfire activity, although there is no discernable effect of 

previous-year fires (Duffield et al. 2013).

Overall demand for warm-weather activities is expected 

to increase due to a direct effect of climate change on season 

length. Temperatures are expected to increase 5 to 12 °F 

across the region by 2100 (see Chapter 3), which is expected 

to result in earlier availability of snow- and ice-free sites 

and an increase in the number of warm-weather days in 

spring and fall. For example, higher minimum temperatures 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
406 USDA Forest Service RMRS-GTR-374. 2018

are associated with increased number of hiking days 

(Bowker et al. 2012). More extreme summer temperatures 

can dampen participation during the hottest weeks of the 

year, and extreme heat scenarios for climate change are expected to reduce visitation (Richardson and Loomis 2004); 

higher maximum summer temperatures are associated with 

reduced participation in warm-weather activities (Bowker 

et al. 2012). The temperature that is considered “extreme” 

may vary between individuals and chosen activities. In 

Bowker et al. (2012), a linear effect of maximum summer 

temperature in the visitor’s home county was included in 

participation models. Extreme heat may shift demand to 

cooler weeks at the beginning or end of the warm-weather 

season, or shift demand to alternative sites that are less exposed to extreme temperatures (e.g., at higher elevations).

Indirect effects of climate change on forested area may 

have a negative effect on warm-weather recreation if site 

availability and quality (e.g., scenic and aesthetic attributes) 

are compromised. However, the effect on warm-weather 

recreation in the Northern Rockies region and its various 

subregions will depend on local effects of climate on forest 

resources.

Potential increases in the likelihood of extreme wildfire 

activity may reduce demand for warm-weather activities in 

certain years because of degraded site desirability, impaired 

air quality from smoke, and limited site access due to fire 

management activities. The Northern Rockies region is 

expected to experience increases in area burned by wildfire, 

average fire size, and fire severity (see Chapter 8), which 

tend to have a negative impact on recreation visitation and 

benefits derived from recreation.

Adaptive capacity among recreationists is high because 

of the large number of potential alternative sites, ability to 

alter the timing of visits, and ability to alter capital investments (e.g., appropriate gear). However, benefits derived 

from recreation may decrease even if substitute activities or 

sites are available (Loomis and Crespi 2004). For example, 

some alternative sites may involve higher costs of access 

(because of remoteness or difficulty of terrain) or congestion 

costs if demand is concentrated among fewer desirable sites. 

In addition, visitors’ ability to alter seasonality of visits may 

be limited because of the timing of scheduled academic 

breaks. Although recreationists’ ability to substitute sites and 

activities is well established, there is less understanding of 

how people substitute across time periods or between large 

geographic regions (e.g., choosing a site in the Northern 

Rockies instead of the Southwest) (Shaw and Loomis 2008). 

In some cases, unique features or strong individual attachment to particular places may limit substitutability.

Projected climate scenarios are expected to result in 

a moderate increase in warm-weather recreation activity 

and benefits derived from these activities. Longer warmweather seasons are likely to increase the number of days 

when warm-weather activities are viable and to increase 

the number of sites available during shoulder seasons. The 

effects of a longer season may be offset somewhat by negative effects on warm-weather activities during extreme heat 

and increased wildfire activity. The likelihood of effects 

on warm-weather recreation is high; the primary driver 

of climate-related changes to warm-weather recreation is 

through direct effects of temperature changes on the demand 

for warm-weather recreation. Climate scenarios outlined 

in Chapter 3 differ in the projected magnitude of warming, 

but overall project warmer temperatures. Indirect effects on 

recreation, primarily through wildfire effects, may be harder 

to project with certainty and precision (particularly at a finegrained geospatial scale).

Cold-Weather Activities

The Northern Rockies region boasts many winter 

recreation sites that in total exhibit a wide range of site 

characteristics and attract local, national, and international 

visitors. Several sites support developed downhill skiing 

and snowboarding operated by special-use permit on lands 

administered by the USFS. Sites for cross-country skiing, 

snowshoeing, and snowmobiling tend to be maintained 

directly by the USFS, although national parks also provide 

access for these activities.

Figure 10.3—Expectations for extent and severity of wildfires 

in a warmer climate will create forest conditions that may 

be less desirable for hiking and other recreational activities 

(photo courtesy of Dave Pahlas, http://IdahoAlpineZone.

com).

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 407

Snow-based recreation is highly sensitive to variations 

in temperature and the amount and timing of precipitation 

as snow. Seasonal patterns of temperature and snowfall determine the likelihood of a given site having a viable season 

and the length of viable seasons (Scott et al. 2008). Lower 

temperatures and the presence of new snow are associated 

with increased demand for skiing and snowboarding (Englin 

and Moeltner 2004). Indirect effects of climate, such as 

changes in scenery and unique features (e.g., glaciers) may 

also affect winter recreation, although these effects are 

expected to be small relative to the effect of changes in 

amount and timing of snowfall.

Climate change is expected to have a generally negative effect on snow-based winter activities, although a 

wide range of effects at local scales is possible because of 

variations across the region in site location and elevation. 

Warmer projected winter temperatures for the region are 

expected to reduce the proportion of precipitation as snow, 

even if the total amount of precipitation does not deviate 

significantly from historical norms (see Chapter 4). The 

rain-snow transition zone (i.e., where precipitation is more 

likely to be snow rather than rain for a given time of year) 

is expected to move to higher elevations, particularly in late 

fall and early spring (Klos et al. 2014). This effect places 

lower elevation sites at risk of shorter or nonexistent winter 

recreation seasons (fig. 10.4). However, the highest elevation areas in the region remain snow dominated for a longer 

portion of the season in future climate scenarios.

Studies of the ski industry in North America uniformly 

project negative effects of climate change (Scott and 

McBoyle 2007). Overall warming is expected to reduce 

expected season length and the likelihood of reliable winter 

recreation seasons (Wobus et al. 2017). Climatic projections 

for the Northern Rockies region (see Chapter 3) are consistent with studies of the vulnerability of ski areas to climate 

change in other regions, where projected effects of climate 

change on skiing, snowboarding, and other snow-based 

recreation activities are negative (Dawson et al. 2009; Scott 

et al. 2008; Stratus Consulting 2009).

Snow-based recreationists have moderate capacity to 

adapt to changing conditions given the relatively large 

number of winter recreation sites in the region. For undeveloped or minimally developed site activities (for example, 

cross-country skiing, backcountry skiing, snowmobiling, 

snowshoeing), recreationists may seek higher elevation 

sites with higher likelihoods of viable seasons. Although 

developed downhill skiing sites are fixed improvements, 

potential adaptations include snowmaking, development 

at higher elevations, and development of new runs (Scott 

and McBoyle 2007). However, the ability of winter tourism 

sector businesses to adapt probably varies considerably. 

Warmer temperatures and increased precipitation as rain 

may increase availability of water for snowmaking in the 

near term during winter, but warmer temperatures may also 

reduce the number of days per season when snowmaking is 

viable.

Changes in Northern Rockies sites relative to other 

regions may also be important. If other regions experience 

relatively large effects of climate on snow-based recreation, 

recreationists may view Northern Rockies sites as a substitute for sites in other regions (e.g., the Southwest), although 

interregional substitution patterns for recreation activities 

are poorly understood (Shaw and Loomis 2008). Further, 

increased interregional substitution combined with shorter 

seasons may result in concentrated demand at fewer sites on 

fewer days, creating potential congestion effects.

The magnitude of climate effects on snow-based winter 

activities is expected to be high. Warmer temperatures 

are likely to shorten winter recreation seasons and reduce 

the likelihood of viable seasons at lower elevation sites. 

Developed sites may have limited ability to adapt to these 

changes unless additional adjacent area is available and 

feasible for expanded development. In comparison to other 

regions, Northern Rockies winter recreation sites may see 

fewer effects from climate change; interregional substitution 

could mitigate losses in some years if participants from 

other regions are more likely to visit Northern Rockies 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Figure 10.4—Cross-country skiing at lower elevation 

locations (shown here in the Beaverhead-Deerlodge 

National Forest) may be vulnerable as snowpack decreases 

in future decades (photo courtesy of U.S. Forest Service).
408 USDA Forest Service RMRS-GTR-374. 2018

sites. The likelihood of effects is expected to be high for 

snow-based recreation, although variation across sites is 

possible because of differences in location and elevation. 

Climate models generally project warming temperatures and 

a higher-elevation rain-snow transition zone, which would 

mean that additional sites would be left exposed to the risk 

of shorter seasons.

Wildlife Activities

Wildlife recreation activities involve terrestrial or 

aquatic animals as a primary component of the recreation 

experience. Wildlife recreation can involve consumptive 

(e.g., hunting) or nonconsumptive (e.g., wildlife viewing, 

birding, catch-and-release fishing) activities. Distinct 

from other types of recreation, wildlife activities depend 

on the distribution, abundance, and population health of 

desired target species. These factors influence activity 

“catch rates,” that is, the likelihood of catching or seeing 

an individual of the target species. Sites with higher catch 

rates can reduce the costs associated with a wildlife activity 

(e.g., time and effort tracking targets) and enhance overall 

enjoyment of a recreation day for that activity (e.g., greater 

number of views of highly valued species).

Participation in wildlife activities is sensitive primarily 

to climate-related changes that affect expected catch rates. 

Catch rates are important determinants of site selection 

and trip frequency for hunting (Loomis 1995; Miller and 

Hay 1981), substitution among hunting sites (Yen and 

Adamowicz 1994), participation and site selection for 

fishing (Morey et al. 2002), and participation in nonconsumptive wildlife recreation (Hay and McConnell 1979). 

Changes to habitat, food sources, or streamflows and water 

temperature (for aquatic species) may alter wildlife abundance and distribution, which in turn influence expected 

catch rates and wildlife recreation behavior.

Wildlife activities may also be sensitive to other direct 

and indirect effects of climate change. The availability of 

highly valued targets affects benefits derived from wildlife 

activities (e.g., cutthroat trout [Oncorhynchus clarkii] for 

cold-water anglers) (Pitts et al. 2012), as does species 

diversity for hunting (Milon and Clemmons 1991) and 

nonconsumptive activities (Hay and McConnell 1979). 

Temperature and precipitation are related to general trends 

in participation for multiple wildlife activities (Bowker 

et al. 2012; Mendelsohn and Markowski 2004), although 

the precise relationship may be specific to the activity or 

species. Some activities such as big game hunting may be 

enhanced by cold temperatures and snowfall at particular 

times to aid in field dressing, packing out harvested animals, and tracking. Other activities may be sensitive to 

direct climate effects similar to warm-weather activities, in 

which moderate temperatures and snow- and ice-free sites 

are desirable.

Warming temperatures projected for the Northern 

Rockies region are expected to increase participation in terrestrial wildlife activities because of an increased number 

of days that are desirable for outdoor recreation. In general, 

warmer temperatures are associated with greater participation in and number of days spent hunting, bird watching, 

and viewing wildlife (Bowker et al. 2012). However, hunting that occurs during discrete seasons (e.g., elk and deer 

hunting season dates managed by States) may depend on 

weather conditions during a short period of time. The desirability of hunting during established seasons may decline as 

warmer weather persists later into the fall and early winter 

and the likelihood of snow cover decreases, reducing harvest rates.

The effects of changes in habitat for target species 

are likely to be ambiguous because of complex relationships among species dynamics, vegetation, climate, and 

disturbances (primarily wildfire and invasive species) 

(see chapter 9), and are likely to be heterogeneous across 

species and habitat types. Overall vegetative productivity 

may decrease in the future, although this is likely to have a 

neutral effect on game species populations, depending on 

the size, composition, and spatial heterogeneity of forage 

opportunities in the future (see Chapter 9). Similarly, the 

effects of disturbances on target species harvest rates are 

ambiguous because it is unknown exactly how habitat composition will change in the future.

Higher temperatures are likely to decrease populations 

of native cold-water fish species as climate refugia retreat 

to higher elevations (see Chapter 5). This change favors 

populations of fish species that can tolerate warmer temperatures. However, it is unclear whether shifting populations 

of species (e.g., substituting rainbow trout [O. mykiss] 

for cutthroat trout) will affect catch rates because relative 

abundance of fish may not necessarily change.

Total precipitation is not projected to change under 

future climate scenarios (see Chapter 3), but increased 

interannual variability in precipitation, the possibility of 

extreme drought, and reduced snowpack could result in 

higher peakflows in winter and lower low flows in summer, 

creating stress for fish populations during different portions of their life histories. The largest patches of habitat 

for cold-water species will be at higher risk to shrink and 

fragment. Increased incidence and severity of wildfire may 

increase the likelihood of secondary erosion events that 

degrade waterways and game species habitat. These effects 

could degrade the quality of individual sites in a given year 

or decrease the desirability of angling as a recreation activity relative to other activities.

The magnitude of climate effects on activities involving terrestrial wildlife is expected to be low overall for 

terrestrial wildlife activities and moderate for fishing. 

Ambiguous effects of vegetative change on terrestrial 

wildlife populations and distribution suggest that conditions 

may improve in some areas and decline in others. Overall 

warming tends to increase participation, but may create 

timing conflicts for activities with defined regulated seasons (e.g., big game hunting) unless the timing of seasons 

is changed. Anglers may experience moderate negative 

effects of climate change on benefits derived from fishing. 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 409

Opportunities for cold-water species fishing are likely to be 

reduced as cold-water refugia retreat to higher elevations or 

are eliminated in some areas. Cold-water species tend to be 

the highest value targets, indicating that this habitat change 

will decrease benefits enjoyed by anglers. Warm-water tolerant species may increasingly provide targets for anglers, 

mitigating reduced benefits from fewer cold-water species. 

Warmer temperatures and longer seasons encourage additional participation, but indirect effects of climate on 

streamflows and reservoir levels could reduce opportunities 

in certain years. The likelihood of climate-related effects 

on wildlife activities is expected to be moderate for both 

terrestrial and aquatic wildlife activities. Uncertainties exist 

about the magnitude and direction of indirect effects of climate on terrestrial habitat and the degree to which changes 

in available target species affect participation.

Gathering Forest Products

Forest product gathering for recreational purposes accounts for a relatively small portion of primary activities 

during visits in the Northern Rockies region, although it 

is relatively more common as a secondary activity. Forest 

products are also important for cultural and spiritual uses, 

which are discussed in Chapters 11 and 12. A small but 

avid population of enthusiasts for certain types of products 

supports a small but steady demand for gathering as a 

recreational activity. Small-scale commercial gathering 

probably competes with recreationists for popular and 

high-value products such as huckleberries (Vaccinium

spp.), although resource constraints may not be binding at 

current participation levels.

Forest product gathering is sensitive primarily to climatic and vegetative conditions that support the distribution 

and abundance of target species. Participation in forest 

product gathering is akin to warm-weather recreation activities because it also depends on moderate temperatures 

and the accessibility of sites where products are typically 

found. Vegetative change due to warming temperatures 

and increased interannual variation in precipitation may 

alter the geographic distribution and productivity of target 

species (see chapters 6 and 7). Increased incidence and 

severity of wildland fires may eliminate sources of forest 

products in some locations (e.g., for berries), but in some 

cases fires may enhance short- or medium-term productivity for other products (e.g., mushrooms). Long-term 

changes in vegetation that reduces forest cover may reduce 

viability of forest product gathering in areas that have a 

high probability of vegetative transition to less productive 

vegetation types.

Recreationists engaged in forest product gathering 

may have the ability to select different gathering sites as 

the distribution and abundance of target species change, 

although these sites may increase the costs of gathering. 

Those who engage in gathering as a secondary or tertiary 

activity may choose alternate activities to complement 

primary activities. Commercial products serve as an 

imperfect substitute for some forest products such as 

Christmas trees.

The magnitude of climate effects on forest product 

gathering is expected to be low. This activity is among the 

less-common primary recreation activities in the region, 

although it may be more often engaged in as a secondary 

or tertiary activity. Longer warm-weather seasons may 

expand opportunities for gathering in some locations, 

although these seasonal changes may not correspond with 

greater availability of target species. The likelihood of 

effects is expected to be moderate, although significant 

uncertainty exists regarding direct and indirect effects on 

forest product gathering. Vegetative changes caused by 

climate changes and disturbances may alter abundance and 

distribution of target species, although the magnitude and 

direction of these effects are unclear.

Water-Based Activities, not Including 

Fishing

Separate from angling, water-based activities are a 

small portion of primary recreation activity participation 

on Federal lands. Upper reaches of streams and rivers are 

generally not desirable for boating and floating. Lakes and 

reservoirs provide opportunities for both motorized and 

nonmotorized boating and swimming, although boating may 

commonly be paired with fishing. Existing stressors include 

the occurrence of drought conditions that reduce water 

levels and site desirability in some years, and disturbances 

that can alter water quality (e.g., erosion events following 

wildland fires).

Even if total precipitation does not change significantly 

under future climate scenarios (see Chapter 3), the availability of suitable sites for non-angling, water-based recreation 

is sensitive to reductions in water levels caused by warming 

temperatures, increased variability in precipitation (including the possibility of severe droughts), and decreased 

precipitation as snow. Reduced water levels may also have 

an indirect effect on the aesthetic qualities of some waterbased recreation sites (e.g., exposure of “bathtub rings” at 

reservoirs with low water levels). Reductions in surfacewater area are associated with decreases in participation 

in boating and swimming activities (Bowker et al. 2012; 

Loomis and Crespi 2004; Mendelsohn and Markowski 

2004), and streamflow is positively associated with number 

of days spent rafting, canoeing, and kayaking (Loomis and 

Crespi 2004). Demand for water-based recreation is also 

sensitive to temperature. Warmer temperatures are generally 

associated with higher participation in water-based activities (Loomis and Crespi 2004; Mendelsohn and Markowski 

2004), although extreme heat may dampen participation for 

some activities (Bowker et al. 2012).

Increasing temperatures, reduced storage of water as 

snowpack, and increased variability of precipitation are 

expected to increase the likelihood of reduced water levels 

and greater variation in water levels in lakes and reservoirs 

on Federal lands (see Chapter 4), which are associated with 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
410 USDA Forest Service RMRS-GTR-374. 2018

reduced site quality and suitability for certain activities 

(fig. 10.5). Increased demand for surface water by downstream users may exacerbate water levels in drought years. 

Warmer temperatures are expected to increase the demand 

for water-based recreation as the viable season lengthens. 

Extreme heat encourages some people to seek water-based 

activities as a climate refuge, although extreme heat also 

discourages participation in outdoor recreation in general 

(Bowker et al. 2012). Overall, projections of water-based 

activities in response to climate change tend to be small 

compared to broad population and economic shifts (Bowker 

et al. 2012).

Climate change is expected to have a moderate effect on water-based activities. Increasing temperatures 

and longer warm-weather seasons are likely to increase 

demand, although the incidence of extreme temperatures 

may dampen this effect in certain years. A higher likelihood of lower streamflows and reservoir levels and 

potential reductions to site aesthetic quality may also 

offset increased demand to some extent. Climate change 

effects are expected to occur with moderate likelihood. 

Climate model projections tend to agree on a range of 

warming temperatures and longer seasons, although 

changes in precipitation are uncertain. Changes in the 

timing of snowmelt may increase the likelihood of 

negative effects to water-based activities (through lower 

summer flows and reservoir levels) that offset increases 

due to warmer temperatures.

Summary

Several recreation activities are considered highly 

sensitive to changes in climate and ecosystem characteristics. However, recreation in the Northern Rockies 

region is diverse, and the effects of climate are likely to 

vary widely between different categories of activities 

and across geographic areas within the region. Overall, 

participation in climate-sensitive recreation activities 

is expected to increase in the region, primarily because 

longer warm-weather seasons will make more recreation 

sites available for longer periods of time.

Increased participation in warm-weather activities is 

likely to be offset somewhat by decreased snow-based 

winter activities. Receding snow-dominated areas and 

shorter seasons in the future are likely to reduce the 

opportunities (in terms of available days and sites) for 

winter recreation.

Beyond these general conclusions, the details of 

changes in recreation patterns in response to climate 

changes are complex. Recreation demand is governed 

by several economic decisions with multiple interacting dependencies on climate. For example, decisions 

about whether to engage in winter recreation, activity 

type (e.g., downhill or cross-country skiing), location, 

frequency of participation, and duration of stay per trip 

depend somewhat on climate and ecological characteristics. On the supply side, site availability and quality 

depend on climate, but the effect may differ greatly 

from one location to another. Thus, climate effects on 

recreation depend on spatial and temporal relationships 

between sites, climate and ecological characteristics, and 

human decisions.

Uncertainty derives from unknown effects of climate 

on site quality and characteristics that are important 

for some recreation decisions (e.g., indirect effects of 

climate on vegetation, wildlife habitat, and species abundance and distribution). The precise effect of climate 

on target species or other quality characteristics may be 

difficult to predict or diverse across the region, yet these 

characteristics play a large role in recreation decisions 

for some activities. Another source of uncertainty is how 

people will adapt to changes when making recreation 

decisions. Interregional and intertemporal substitution 

behavior is not yet well understood (Shaw and Loomis 

2008). This may be important for the Northern Rockies 

region if in the future some sites exhibit relatively little 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Figure 10.5—Algal blooms, shown 

here in Hayden Lake, Idaho, 

may become more common 

in a warmer climate. These 

conditions are undesirable 

for water-based recreation 

and some fish species (photo 

courtesy of Panhandle Health 

District).
USDA Forest Service RMRS-GTR-374. 2018 411

effect from climate change compared with sites in other 

regions. For example, winter recreation sites in the 

Northern Rockies may experience shorter or lower quality seasons in the future but see increased demand if the 

quality of sites in other regions becomes relatively worse 

in the future.

Substitution is likely to be an important adaptation 

mechanism for recreationists. Many recreation activities 

that are popular in the region may have several alternate 

sites, or timing of visits can be altered to respond to 

climate changes. However, substitution may represent a 

loss in benefits derived from recreation even if it appears 

that participation changes little (Loomis and Crespi 

2004); the new substitute site may be slightly more costly to access, or slightly lower quality than the preferred 

visit prior to climate change. This represents a decrease 

in benefits to the person engaging in recreation.

Adapting Recreation to the 

Effects of Climate Change

Adapting recreation management to climate change in 

the Northern Rockies region will be critical to ensure that 

recreation opportunities exist in the future.

Adaptation by Recreation Participants

Increasing temperatures with changing climate will 

have significant negative effects on snow-based recreation. Length of the snow-based recreation season is 

likely to decrease, and the quality of the snow during the 

season may also decrease (be wetter).

Water-based recreationists may adapt to climate 

change by choosing different sites that are less susceptible to changes in water levels (e.g., by seeking 

higher-elevation natural lakes) and changing the type of 

water-based recreation activity they engage in (e.g., from 

motorized boating on reservoirs to nonmotorized boating 

on natural lakes).

Hunters may need to adapt by altering the timing 

and location of hunts. However, State rules on hunting 

season dates impose a constraint on this behavior unless 

States change hunting seasons based on expected climate 

changes. Hunters may also target different species if the 

abundance or distribution of preferred species changes in 

the future.

Like hunters, wildlife viewers may change the timing 

and location of viewing experiences and target different 

species. Viewing is not typically governed by Stateregulated seasons, so wildlife viewers may have more 

flexibility to shift timing to coincide with appropriate 

weather conditions or the movement of species into accessible areas. However, adaptation options may be more 

limited if the abundance or distribution of highly valued 

species significantly decreases the likelihood of viewing, 

and limited high-quality substitute species are available.

Anglers may adapt by choosing different species 

to target (for example, shifting from cold-water to 

warm-water tolerant species) and choosing sites that are 

relatively less affected by climate change (e.g., higher 

elevation secondary-stem reaches of streams). The former is less costly than the latter, although some anglers 

may place a high value on certain target species and have 

a lower willingness to target warm-water species that 

may thrive in place of cold-water species.

Adaptation by Public Land Managers

Managers may need to reconsider how infrastructure 

investments and the provision and maintenance of 

facilities align with changing ecological conditions 

and demands for recreation settings. The Recreation 

Opportunity Spectrum can be used to match changing 

conditions and preferences to the allocation of available 

recreation opportunities. Adaptation by managers may 

take the form of responding to changing recreation patterns, but also may involve helping to shape the settings 

and experiences that are available to recreation users on 

public lands in the future.

For winter recreation, a general adaptation strategy 

may be a transition to recreation management that 

addresses shorter winter recreation seasons and changing recreation use patterns (table 10.4). Specifically, 

opportunities may exist to expand facilities where 

concentrated use increases, and options for snow-based 

recreation can be diversified to include more snowmaking, additional ski lifts, and runs at higher elevations. In 

some cases, however, adaptations related to the supply 

and quality of winter recreation opportunities could 

result in tradeoffs with other activities, such as warmweather access to undeveloped higher elevation sites or 

effects of snowmaking on streamflow in winter versus 

summer.

With higher temperatures and earlier snowmelt, 

warm-weather activity seasons are likely to lengthen. 

Recreation managers have options for responding to 

changing patterns in warm-season recreation demand in 

order to provide sustainable recreation opportunities. A 

first step will be to conduct assessments to understand 

the changing patterns of use (table 10.4). Then, adjustments can be made to increase the capacity of recreation 

sites that are showing increased use (e.g., campgrounds 

can be enlarged, and more fences, signs, and gates 

can be installed where necessary). The potential for 

congestion and damage to resources due to increases 

in use for some sites may, in part, drive such adjustments. However, there may be some limits to increasing 

the capacity of recreation sites (e.g., restrictions for 

developed recreation sites under the U.S. Fish and 

Wildlife Service [USFWS] Northern Continental Divide 

Ecosystem Grizzly Bear Conservation Strategy; USFWS 

2013). The timing of actions such as trail closures, food 

storage orders, and special-use permits may also need to 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
412 USDA Forest Service RMRS-GTR-374. 2018 Table 10.4—Adaptation options that address climate change effects on recreation in the Northern Rockies. Sensitivity to climatic variability and change: Ice- and snow-based recreation is highly sensitive to variations in temperature and the amount and timing of precipitation as snow. Adaptation strategy/approach: Transition to address shorter average winter recreation seasons and changing use patterns. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Maintain current infrastructure and expand facilities in areas where concentrated use increases. Develop options for diversifying snow-based recreation, such as cat-skiing, helicopter skiing, additional ski lifts, additional higher elevation runs, toboggan runs, snow making, and back country yurts. Conduct safety education to make the public aware of increased risk of avalanche and thin ice. Where can tactics be applied? Snow recreation areas and major lakes In and around existing permitted areas; within driving distance of population centers Snow recreation areas and major lakes Sensitivity to climatic variability and change: The warm weather recreation season will increase in length with increasing temperatures and earlier snowmelt. Adaptation strategy/approach: Provide sustainable recreation opportunities in response to changing demand. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Assess to understand changes in use patterns and identify demand shifts. Adjust capacity of recreation sites (e.g., enlarge campgrounds, collect additional fees, and install infrastructure such as fences, signs and gates). Adjust timing of actions such as road and trail closures, food storage orders, and special-use permits. Where can tactics be applied? At multiple levels (national, regional, forest- level, and local) Where demand increases on Federal lands, as appropriate Federal lands Sensitivity to climatic variability and change: The seasonality of whitewater rafting will shift with increasing temperatures and shifts in the timing of peak streamflows. Adaptation strategy/approach: Increase management flexibility and facilitate transitions to meet user demand and expectation. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Vary permit season to adapt to changes in peakflow and duration. Educate the public about changing river conditions. n/a Where can tactics be applied? Permitted rivers Permitted rivers n/a Sensitivity to climatic variability and change: Increases in flooding, fire, and other natural disturbances will cause damage to infrastructure. Adaptation strategy/approach: Manage recreation sites to mitigate risks to public safety and infrastructure and to continue to provide recreation opportunities. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Assess to determine which recreation sites and infrastructure are at risk from increased flooding and other natural hazards. Prioritize post-disturbance treatments, including relocation, arming, and other mitigation measures. Invest strategically in developed recreation facilities, prioritizing those that will be viable in the future and accommodate changing use patterns. Where can tactics be applied? Federal lands Federal lands Federal lands

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 413

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

be adjusted within the context of providing sustainable 

recreation. For example, the season for whitewater rafting permits may need to be modified to adjust to shifts in 

timing of peakflows (table 10.4).

Increased frequency of disturbances, such as fire and 

flooding, is likely to cause increased damage to infrastructure associated with multiple types of recreation 

activities. Recreation sites can be managed to decrease 

risks to public safety and infrastructure (table 10.4). 

Assessments can be used to determine which sites and 

infrastructure are most at risk from disturbance, and 

strategic investments can be made in those facilities that 

are expected to be viable in the future and accommodate 

changing use patterns.

More-specific details on adaptation strategies and tactics that address climate change effects on recreation in 

each Northern Rockies Adaptation Partnership subregion 

are in Appendix 10A.

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Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 415

Appendix 10A—Adaptation Options for Recreation in the 

Northern Rockies.

The following tables describe climate change sensitivities and adaptation strategies and tactics for recreation, developed 

in a series of workshops as a part of the Northern Rockies Adaptation Partnership. Tables are organized by subregion within 

the Northern Rockies. See Chapter 10 for summary tables and discussion of adaptation options for recreation.

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
416 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.1—Adaptation options that address climate change effects on recreation in the Central Rockies subregion. Sensitivity to climatic variability and change: Risk to infrastructure with changes in the frequency and severity of natural hazards and disturbances. Adaptation strategy/approach: Manage recreation sites to mitigate natural hazards. Strategy objective: Increase the resiliency of recreation sites by reducing threats and encouraging coordination with partners. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Maintain safety by assessing risk factors. Identify flood plains and risks to campgrounds (developed sites) and dispersed recreation sites. Identify effects after disturbance to recreation sites and prioritize treatments or conversions (e.g., relocate, arming, and/or mitigation measures). Tactic effectiveness (risks) Moderate–high Moderate–high High Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Forest lands or adjacent lands; high risk disturbance areas Forest wide National Forest System lands Opportunities for implementation Work with other agencies, such as the Federal Emergency Management Agency; use existing data for tree mortality and add species and overlay of use areas Model risk of storm events, such as rain- on-snow events and flood events (including post-fire floods) Rapid assessment teams; learn from other agencies, such as the National Park Service Cost Moderately expensive Moderately expensive Moderately expensive Barriers to implementation Some: organizational will; leadership commitment; internal resistance, priority setting; integration and interpretation of data and models Some: external partner support and coordination Some: forest capacity (resources and funding); public resistance to relocations and closures

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 417 Table 10A.2—Adaptation options that address climate change effects on recreation in the Central Rockies subregion. Sensitivity to climatic variability and change: Changes in demand for warm-weather recreation. Adaptation strategy/approach: Transition to address extended seasons or changing use patterns. Strategy objective: Provide sustainable recreation opportunities in response to changing demand. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Assess use patterns to understand demand shifts and address recreation niches identified for the area. Identify natural resource impacts and increase coordination with partners and concessionaires. Adjust capacity issues such as enlarging campgrounds and fee opportunities. Tactic effectiveness (risks) Moderate Moderate-high High Implementation urgency Near term Mid term Mid term Where can tactics be applied? (geographic) National, regional, forest and local levels Forest level Local level Opportunities for implementation Coordinate with states, local communities; enhance National Visitor Use and Monitoring processes with sub-surveys Annual operation meetings, meetings with target user groups, special interest groups meetings Limited opportunities Cost Moderately expensive Moderately expensive Moderate – expensive Barriers to implementation Ability to acquire or predict patterns of use is difficult because demand is difficult to determine; lack of leadership support to engage in studies; low priority in program of work regionally and nationally; declining budgets and staffing Shifting demographics Political and environmental justice fees

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
418 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.3—Adaptation options that address climate change effects on winter recreation in the Central Rockies subregion. Sensitivity to climatic variability and change: Threats to winter recreation Adaptation strategy/approach: Transition to address shorter average season and changing use patterns. Strategy objective: Provide sustainable recreation in response to changing demand. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Shift winter use, address safety concerns, and engage partners to implement changes needed in use. Create management areas and direction addressing concentrated winter use areas through forest planning; communicate with partners, cooperators and other agencies and maintain recreation internet sites with access information. Relocate sites as necessary and add signs to guide the public. Tactic effectiveness (risks) Moderate Moderate-high Moderate Implementation urgency Mid term Near term Mid term Where can tactics be applied? (geographic) Winter recreation sites Designated management areas Winter recreation sites Opportunities for implementation Forest plan revision; project planning; avalanche centers; state agreements Forest Planning – Revision Efforts Project planning Avalanche Centers State Agreements Integrate projects to include recreation; large landscape efforts; adjusted stewardship law to include recreation Cost Moderately expensive Moderately expensive Expensive Barriers to implementation Our ability to respond Timing, unclear direction for those not in revision; lacks leadership support to engage Environmental resources; cultural and political 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 419 Table 10A.4—Adaptation options that address climate change effects on recreation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Recreation access needs may change with climate change, including change to location, season of use, type of use, and duration of use. Adaptation strategy/approach: Ensure that access is adequate for projected recreation use and demand and compatible with resource and climate change conditions. Strategy objective: Facilitate transition of recreation access to ensure relevancy and resiliency by season of use and changing use patterns. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Evaluate and prioritize existing access by season (e.g., trailheads and trails) to ensure consistency with changing recreation opportunity spectrum settings with climate change. Identify new access needs and potential changes to existing access by season. Strategically invest in new and potential changes to existing access by season. Tactic effectiveness (risks) High High High/moderate Implementation urgency Near term Mid term Mid term Where can tactics be applied? (geographic) Federal lands Federal lands Federal lands Opportunities for implementation Partners Partners Partners Cost Moderate Moderate Moderate Barriers to implementation Some (funding/capacity) Some (funding/capacity) Some (funding)

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
420 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.5—Adaptation options that address climate change effects on recreation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Recreation settings (Recreation Opportunity Spectrum and scenery), both motorized and non-motorized, during all seasons will be affected by the expected changes in climate. Adaptation strategy/approach: Align our recreation settings with changing landscape conditions and demand. Strategy objective: Facilitate transition of recreation settings to achieve flexibility, relevancy and resiliency; maintain those recreation settings that complement our niches. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Assess existing recreation opportunity spectrum settings and scenic character to determine which are most vulnerable to climate change effects. Develop management strategies to shift or maintain existing recreation opportunity spectrum settings and scenic character in response to climatic change. Develop a sub-regional niche. Tactic effectiveness (risks) High High Moderate/low Implementation urgency Mid term Mid term Near term Where can tactics be applied? (geographic) Federal lands Federal lands Federal lands Opportunities for implementation None None None Cost Moderately expensive Moderately expensive Inexpensive Barriers to implementation Some barriers Some barriers None

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 421 Table 10A.6—Adaptation options that address climate change effects on recreation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Cultural and heritage resources may be affected by changes in climate, technology, demographics, and culture. Adaptation strategy/approach: Protect cultural and heritage sites and the sacred uses of traditional cultural landscapes. Strategy objective: Acknowledge the importance of cultural and heritage sites and protect valuable sites. Specific tactic – A Specific tactic – B Tactic Inventory and identify those areas at most risk to climate change and changes in use patterns, and mitigate the effects Develop interpretation and education opportunities to educate the public in areas or resources most at risk. Tactic effectiveness (risks) Moderate Moderate Implementation urgency Near term Near term Where can tactics be applied? (geographic) Greater Yellowstone Area Greater Yellowstone Area Opportunities for implementation Tribes; Tribal Historic Preservation Office; universities, State Historic Preservation Officer; Passport in Time volunteers Tribes; Tribal Historic Preservation Office; universities, State Historic Preservation Officer; Passport in Time volunteers Cost Expensive Moderately expensive Barriers to implementation Some: Forest Service capacity and funding Some: Forest Service capacity and funding

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
422 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.7—Adaptation options that address climate change effects on recreation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: Recreation user demand and the shift in recreation activity, amount of use, and patterns of use will be driven by climate change, technology, demographics, and culture. Adaptation strategy/approach: Align our recreation opportunities with future demand to commercial (permitted) and non-commercial recreation users. Strategy objective: Facilitate transition of recreation opportunities to achieve flexibility, relevancy and resiliency. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Understand the changes in demand, demographics, and economic trends, both regionally and nationally. Conduct research to clearly identify localized impacts of climate change. Conduct research to understand the latest and upcoming technology that impacts recreation. Tactic effectiveness (risks) High High High Implementation urgency Near term Near term Near term Where can tactics be applied? (geographic) Opportunities for implementation Partners, research, university, non- governmental organizations Partners, research, university, non- governmental organizations Partners, research, university, non-governmental organizations Cost Moderate Moderate Moderate Barriers to implementation Some: expertise, agency culture Some: expertise, agency culture Some: expertise, agency culture

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 423 Table 10A.8—Adaptation options that address climate change effects on recreation in the Eastern Rockies subregion. Sensitivity to climatic variability and change: The future viability of recreation facilities will be affected by changes in climate. Adaptation strategy/approach: Provide recreation facilities that accommodate future demand, and reduce user and natural resource conflicts. Strategy objective: Facilitate transition of recreation opportunities to achieve flexibility, relevancy and resiliency. Specific tactic – A Specific tactic – B Specific tactic – C Tactic Prioritize existing recreation facilities, by season, for viability, investment, and change in services. Invest strategically in developed recreation facilities. Design facilities for flexibility in use. Tactic effectiveness (risks) Moderate Moderate-high Moderate Implementation urgency Near term Mid term Mid term Where can tactics be applied? (geographic) Opportunities for implementation Partners, including permittees, public and non- governmental organizations None None Cost Moderate Expensive Moderate Barriers to implementation Some: funding, internal agency Some: funding Some: funding and capacity

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
424 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.9—Adaptation options that address climate change effects on recreation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Archeological sites are susceptible to damage and destruction with increase in wildland fires, erosion and floods, vandalism due to increased recreation activities and longer summer season, and rot from loss of protective snow cover hiding archeological sites. Adaptation strategy/approach: Get cultural resources more involved in the climate change discussion. Strategy objective: Increase education and reduce stressors. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Increase pro-active surveys and site recording. Increase post-fire inventories. Prioritize site sensitivities and management allocation. Mitigate adverse effects. Tactic effectiveness (risks) High High Medium Medium-high Implementation urgency Near term Near term Near term Near term Where can tactics be applied? (geographic) High elevation – determine locations by predictive modeling In burned areas Unit wide Site specific Opportunities for implementation Section 110 of National Historic Preservation Act; engage with university partners; historical societies; Passport in Time projects Burned area emergency response; engage with university partners Forest Service manual Section 110 of National Historic Preservation Act (when not related to specific undertaking) Cost Moderately expensive Moderately expensive Inexpensive Expensive Barriers to implementation Forest leadership team may not see benefit, would rather concentrate on support to other functions Limitation of use of burned area emergency response funds None Major costs

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 425 Table 10A.10—Adaptation options that address climate change effects on recreation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Infrastructure location, sizing, safety, and resource protection. Will our infrastructure be able to accommodate the projected future use in a safe manner, considering shorter winters with less snow, increased and earlier runoff, increased erosion, increased hazard trees from insects, disease and windthrow mortality, population shifts to higher elevation, and rapidly growing outdoor recreation locations? Adaptation strategy/approach: Proactively determine sites where projected climate change impacts may cause safety, resource or recreation-quality issues. Strategy objective: Assess infrastructure and set priorities while considering limited funding and capacity. Specific tactic – A Specific tactic – B Tactic Install appropriately sized culverts; relocate infrastructure; or eliminate infrastructure. Develop additional restrictions in the permitting process, seasonal closures or allowable uses. Tactic effectiveness (risks) Very high Medium Implementation urgency Near to mid term, unless major infrastructure, then 50 years Near term Where can tactics be applied? (geographic) After catastrophic events using burned area emergency response funds; first priorities from climate analysis Where needed – site specific Opportunities for implementation Department of Transportation, Emergency Relief for Federally Owned Roads Existing user groups Cost Expensive, except when incorporated in already funded projects. Moderately expensive – staff time Barriers to implementation None to major: funding; political and social barriers to road closures Some barriers: social and political 

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
426 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.10 (cont.)—Adaptation options that address climate change effects on recreation in the GYA Subregion Sensitivity to climatic variability and change: Infrastructure location, sizing, safety, and resource protection. Will our infrastructure be able to accommodate the projected future use in a safe manner, considering shorter winters with less snow, increased and earlier runoff, increased erosion, increased hazard trees from insects, disease and windthrow mortality, population shifts to higher elevation, and rapidly growing outdoor recreation locations? Adaptation Strategy / Approach: Proactively determine sites where projected climate change impacts may cause safety, resource or recreation-quality issues. Strategy Objective: Assess infrastructure and set priorities while considering limited funding and capacity. Specific Tactic – C Specific Tactic – D Tactic Develop new opportunities or new recreation sites; be proactive in encouraging use in locations where the use will be sustainable and resources can support the use. Monitor closure and restriction dates and set trigger points to determine changes. Tactic effectiveness (risks) Very high Moderate Implementation urgency Near – mid term Near term Where can tactics be applied? (geographic) Urban interface Site specific Opportunities for implementation Any rec site planning process Unit level; user groups Cost Expensive Moderately expensive – staff time Barriers to implementation Some Some: lack of staff time; lack of priority

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 427 Table 10A.11—Adaptation options that address climate change effects on recreation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Lower snow amounts, earlier snowmelt and a longer summer season. Adaptation strategy/approach: Focus on regulation, education, enforcement, and infrastructural changes. Strategy objective: Increase education and reduce stressors. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Adjust dates of orders, as needed, such as extended dates of food storage, travel management, closures and trail shares. Implement social media technology to disperse use, direct users, educate, and promote etiquette. Engage Chambers of Commerce and Development organizations to help deal with the increased pressures on forest and park resources. Install infrastructure as needed (e.g., fences, signs, gates). Tactic effectiveness (risks) Medium–high Medium–high Low–medium Moderate Implementation urgency Near term Near term Mid to long term Near term Where can tactics be applied? (geographic) Anywhere appropriate, but especially in areas with high occurrence of resource-user conflicts Everywhere – messages can be general or site specific Starting with the larger urban centers (i.e. Jackson, Bozeman, Cody, Idaho Falls and Billings) Anywhere appropriate Opportunities for implementation Laws; revised travel management The “GYA app”; National Geographic Magazine Chambers of Commerce; state departments of tourism; state development councils; regional- scale employers; influential people who settle in the GYA User groups; businesses Cost Inexpensive Inexpensive to medium Medium Inexpensive (with partners) Barriers to implementation Small to large, depending on social/cultural opposition from users and communities Medium to small: lack of coverage in remote areas and seniors not using social media; cost barrier Medium to high: internal cultural barriers and political differences and external barriers Low to implement; high to avoid vandalism

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
428 USDA Forest Service RMRS-GTR-374. 2018 Table 10A.12—Adaptation options that address climate change effects on recreation in the Greater Yellowstone Area subregion. Sensitivity to climatic variability and change: Shorter winters with less snow, and wetter or icier snow. Adaptation strategy/approach: Consider diversifying permitted activities, assess infrastructure and recreation sites, and develop prioritization process and criteria. Strategy objective: Increase knowledge, assess options, and engage industry and community partners. Specific tactic – A Specific tactic – B Specific tactic – C Specific tactic – D Tactic Develop options for diversifying snow-based recreation. Use master development plan to determine if we can add uses and extend seasons (or modify the plan). Examine viability of agency snow-based recreation sites, permitted downhill resorts and all permitted winter operations. Monitor snow dates, snow event dates, and snowpack depth. Tactic effectiveness (risks) High in the short-term; must consider cost exclusivity and resource impacts Low–medium Low Moderate Implementation urgency Mid term Mid term Mid–long term Near term Where can tactics be applied? (geographic) For permitted areas, in and around the existing permitted area, within driving distance of population centers Within and around permitted area In and around recreation area Existing snow telemetry (SNOTEL) sites Opportunities for implementation Unit Cost Inexpensive (especially with partners) Barriers to implementation Low to implement; high to avoid vandalism

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 429

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Table 10A.13—Adaptation options that address climate change effects on recreation in the Western Rockies subregion.

Sensitivity to climatic variability and change: Increased human exposure to contaminated sediment due to dropping lake levels in the Coeur d’Alene basin and/or increased desire for water-based recreation in higher temperatures in the contaminated areas.Adaptation strategy/approach: Avoidance of contaminated areas.Strategy objective: Reduce stressors/threat and increase knowledge.

Specific tactic – A Specific tactic – B Specific tactic – C

Tactic Cap or harden contaminated areas. Establish vegetation barriers. Concentrate use in areas that have been 

hardened. 

Tactic effectiveness (risks) High in the short-term (requires 

maintenance)

High Moderate to low.

Implementation urgency Near term (but ongoing in long term) Near term (but ongoing in long term) Near term (but ongoing in long term)Where can tactics be applied? (geographic)

Throughout the basin, but focus on priority areas identified in the Coeur d’Alene Basin Restoration Plan Environmental Impact Statement

Throughout the basin, but focus on priority areas identified in the Coeur d’Alene Basin Restoration Plan Environmental Impact Statement

Throughout the basin, but focus on priority areas identified in the Coeur d’Alene Basin Restoration Plan Environmental Impact Statement

Opportunities for implementation Federal, State, tribal, non-governmental 

organization partners

Federal, State, tribal, non-governmental organization partners

Federal, State, tribal, non-governmental organization partners

Cost Moderately expensive Moderately expensive Moderately expensiveBarriers to implementation Issues with sensitive species or other 

resource concerns

Minimal to none Social
430 USDA Forest Service RMRS-GTR-374. 2018

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region Table 10A.14—Adaptation options that address climate change effects on recreation in the Western Rockies subregion. Sensitivity to climatic variability and change: Increased desire for water-based recreation with higher temperatures will lead to increased dispersed recreation sites in riparian areas. Adaptation strategy/approach: Limit expansion of sites and pioneering of new sites. Strategy objective: Coordinate (e.g., with other agencies and the public); reduce stressors/threat. Specific tactic – A Specific tactic – B Tactic Educate the public and post signs to prevent expansion of dispersed recreation sites in riparian areas. Design measures for resource protection, such as blocking access to riparian areas, and revegetating impacted areas. Tactic effectiveness (risks) Moderate Moderate Implementation urgency Near term (ongoing to long term) Near term (ongoing to long term) Where can tactics be applied? (geographic) Riparian areas on Federal lands Riparian areas on Federal lands Opportunities for implementation Federal, State, tribal, and private partnerships Federal, State, tribal, and private partnerships Cost Moderately expensive Moderately expensive

Barriers to implementation Social Social; recognizing treaty rights to maintain access to 

traditional family use areas
USDA Forest Service RMRS-GTR-374. 2018 431

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Table 10A.15—Adaptation options that address climate change effects on recreation in the Western Rockies subregion.

Sensitivity to climatic variability and change: Cultural/heritage recreation and tourism (e.g., Nimiipuu Trail and Lewis and Clark Trail) and associated scenic driving recreation will likely be affected by increased wildland fire with changing climate. Adaptation strategy/approach: Manage vegetation to limit wildfire impacts on recreation and tourism.Strategy objective: Promote resiliency.

Specific tactic – A Specific tactic – B

Tactic Reduce stand density, and vary age class and species 

composition through vegetation management and/or prescribed fire.

Re-establish native vegetation (e.g., forbs, grasses, and conifers such as whitebark pine); slow spread and reduce populations of invasive species.

Tactic effectiveness (risks) High to moderate Moderate to lowImplementation urgency Near term Near termWhere can tactics be applied? (geographic)

Within scenic corridors Within scenic corridors

Opportunities for implementation Tribal partnerships and collaborative partnerships Cross-regional genetics improvement programs; Federal, tribal, State, and private partnershipsCost Moderately expensive ExpensiveBarriers to implementation Some (opponents to vegetation management as a tool) Some (difficulty with implementation success)
432 USDA Forest Service RMRS-GTR-374. 2018

Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region Table 10A.16—Adaptation options that address climate change effects on recreation in the Western Rockies subregion. Sensitivity to climatic variability and change: Seasonality of whitewater rafting will likely shift with changing climate and timing of peak flows. Adaptation strategy/approach: Increase management (primarily permitting) flexibility. Strategy objective: Promote resiliency. Specific tactic – A Specific tactic – B Tactic Vary permit season to adapt to changes in peak flow and duration. Educate the public about changes in peak flows and permitting. Tactic effectiveness (risks) Moderate High to moderate Implementation urgency Mid term Mid term Where can tactics be applied? (geographic) Permitted rivers Permitted rivers Opportunities for implementation Agency partnerships Agency partnerships Cost Low Low

Barriers to implementation Social Social
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Chapter 10: Effects of Climate Change on Recreation in the Northern Rockies Region

Table 10A.17—Adaptation options that address climate change effects on recreation in the Western Rockies subregion.

Sensitivity to climatic variability and change: Winter recreation (ice fishing, cross-country skiing, snowmobiling) will be at risk with increased temperatures.Adaptation strategy/approach: Increase management (primarily permitting) flexibility. Strategy objective: Promote resiliency.

Specific tactic – A Specific tactic – B

Tactic Maintain current infrastructure and expand facilities in areas 

where concentrated use increases (anticipate additional use as lower elevation areas [Missoula] have reduced snowpacks).

Conduct safety education for increased risk (avalanche potential and thinning ice sheets).

Tactic effectiveness (risks) Moderate ModerateImplementation urgency Near term Near termWhere can tactics be applied? (geographic)

Snow play areas and major lakes Snow play areas and major lakes

Opportunities for implementation Fees PartnershipsCost Moderately expensive LowBarriers to implementation Social; expense Social (people do not always listen)
434 USDA Forest Service RMRS-GTR-374. 2018

Introduction

In this chapter, we focus on the ecosystem services 

provided to people who visit, live adjacent to, or otherwise 

benefit from natural resources on public lands. Communities 

in the Forest Service, U.S. Department of Agriculture 

(USFS) Northern Region and the Greater Yellowstone Area 

(GYA), hereafter called the Northern Rockies region, are 

highly dependent on ecosystem services from water, soil, 

and air that will be affected by climate change in a variety 

of ways. Every community in the region will feel these 

impacts. We link biophysical effects associated with climate 

change, as described in previous chapters, with potential 

effects on the well-being of humans and communities, and 

identify strategies for adapting to climate-induced changes 

and prioritizing among competing interests. First, we introduce ecosystem services and how to describe and measure 

them. Second, we describe how people and communities 

currently use and benefit from public lands in the Northern 

Rockies region, as well as existing stressors that may affect 

the ability of communities to adapt to a changing climate. 

Third, we discuss climate change effects on specific ecosystem services. Finally, we identify adaptation strategies that 

can help reduce negative effects on ecosystem services, and 

discuss the ability of public agencies and communities to 

respond to climate change (adaptive capacity).

Ecosystem services are benefits to people from the natural environment. These include timber for wood products, 

clean drinking water for downstream users, recreation 

opportunities, and spiritual and cultural connection to the 

environment and natural resources. An ecosystem services 

perspective extends the classification of multiple uses to a 

broader array of services or values (Collins and Larry 2007).

Ecosystem services are commonly placed in the following four categories (Millenium Ecosystem Assessment 

2005):

• Provisioning services—products obtained from 

ecosystems, including timber, fresh water, wild foods, 

and wild game

• Regulating services—benefits from the regulation 

of ecosystem processes, including the purification 

of water and air, carbon sequestration, and climate 

regulation

• Cultural services—nonmaterial benefits from 

ecosystems, including spiritual and religious values, 

recreation, aesthetic values, and traditional knowledge 

systems

• Supporting services—long-term processes that 

underlie the production of all other ecosystem 

services, including soil formation, photosynthesis, 

water cycling, and nutrient cycling

Categorizing ecosystem services in this manner helps 

identify the ways in which natural resources and processes 

benefit humans, and how changes in the natural environment will affect these benefits. Climate change will affect 

the quality and quantity of ecosystem services provided by 

public lands. Establishing the link among natural processes, 

ecosystem services, and human benefits helps clarify the 

communities or types of people most vulnerable to a changing climate.

Although ecosystem service categories help organize our 

understanding of the relationship between natural resources 

and human benefits, this simple approach may obscure complex relationships between natural and human systems. Two 

important caveats are relevant to discussions of ecosystem 

services and anticipated climate change effects. First, these 

categories are not exclusive, and many natural resources fall 

under multiple categories, depending on the context. For 

example, the consumption of fresh water can be considered 

a provisioning service, the process of purifying water a 

regulating service, the use of fresh water for recreation a 

cultural service, and the role of fresh water in the life cycle 

of organisms a supporting service. Second, these categories 

are interdependent, such that individual services would not 

exist without the functioning of a broad set of ecosystem 

services.

To address the challenges of ecosystem services falling 

into multiple, interdependent categories, Boyd and Krupnick 

(2009) describe ecosystems as collections of commodities 

linked by a range of biophysical processes, delineating 

biophysical inputs and outputs, ecological endpoints, and 

transformations. In this framework, fresh water is an output 

from a filtration process, an ecological endpoint in itself as 

drinking water, and then an input for the endpoints of recreation and plant and animal populations. This framework 

facilitates assessment of ecosystem service vulnerability by 

allowing analysts to identify ecosystem service endpoints 

Chapter 11: Effects of Climate Change on 

Ecosystem Services in the Northern Rockies 

Region

Travis Warziniack, Megan Lawson, and S. Karen Dante-Wood
USDA Forest Service RMRS-GTR-374. 2018 435

and connect changes in inputs and processes caused by climate change to changes in ecosystem service provision.

This framework and the subsequent distinction between 

natural resources that are endpoints, inputs, and outputs, 

provide a helpful approach to measuring ecosystem services. 

Later in this chapter, we identify the most significant ecosystem services in the Northern Rockies region and describe 

how they are expected to change.

Ecosystem Services and 

Public Lands

The evaluation of ecosystem services in this assessment 

is consistent with Federal agency management requirements. Under the Forest Planning Rule of 2012, the USFS 

is required to formally address ecosystem services in land 

management plans for national forests (USDA FS 2012). 

The National Park Service (NPS) does not have specific 

mandates concerning ecosystem services, but the agency 

has incorporated ecosystem service considerations into 

management planning and made ecosystem services a key 

part of its 2014 Call to Action (NPS 2014). The Bureau of 

Land Management (BLM), U.S. Department of the Interior 

(USDOI) has also identified nonmarket environment values, 

synonymous with ecosystem services, as an increasingly important consideration for land management (Winthrop n.d.).

Although all natural systems provide some type of 

ecosystem services, managing for ecosystem services on 

public lands involves specific considerations that make it 

especially important to identify the endpoints, how they 

are used, and which ones are most susceptible to disruption 

from a changing climate. There are many beneficiaries from 

ecosystem services provided by public lands, including 

neighboring communities, nonlocal visitors, and people 

who may never visit or directly use the lands but gain satisfaction from knowing a resource exists and will be there 

for future generations (Kline and Mazzotta 2012). This is 

particularly true for iconic landscapes and rivers in the study 

area such as Yellowstone National Park, Glacier National 

Park, the Salmon River, and the Selway River (Borrie et al. 

2002; Chouinard and Yoder 2004; Mansfield et al. 2008; 

O’Laughlin 2005; Pederson et al. 2006).

Mandates to manage for multiple use of natural resources 

can create situations in which some ecosystem services 

conflict with others. For example, managing lands for 

nonmotorized recreation may conflict with managing for 

motorized recreation, timber, and mining, but it could 

complement management for biodiversity and some wildlife 

species. Ecosystem services from public lands are critical 

for neighboring communities, particularly in rural areas of 

the Northern Rockies region, where people rely on these 

lands for fuel, food, water, recreation, and cultural connection. Decreased quantity and quality of ecosystem services 

produced by public lands will affect human systems that 

rely on them, requiring neighboring communities to seek 

alternative means of providing these services or to change 

local economies and lifeways.

Management decisions for public lands can substantially 

affect ecosystem service flows, with cascading effects 

on numerous users. This chapter is intended to highlight 

potential climate change effects on ecosystem service flows, 

for which management decisions can help users mitigate 

or adapt to these effects and illustrate the tradeoffs in the 

decisionmaking process. The concept of ecosystem services 

is somewhat new, so data on ecosystem services are scarce. 

In this chapter, we use quantitative data when possible, but 

we often rely on qualitative descriptions or proxy measures. 

Demographic and economic factors often have a significant 

effect on ecosystem services, providing an important context 

for understanding the effects of climate change.

Ecosystem Services in the 

Northern Rockies Region

The USFS Northern Region Resource Information 

Management Board identified ecosystem services that are 

used by a large number of people and can also be affected 

by management decisions. Using the standard categories 

just discussed, we focused on provisioning, regulating, and 

cultural ecosystem services. Supporting services were not 

included because, although important, they are largely indirect services that are inputs to other biophysical processes, 

and are unlikely to be directly affected by management 

decisions. Note that even though we have grouped ecosystem services into provisioning, regulating, and cultural 

services in this chapter, these categories are not definitive; 

many could have been included in an alternative category. 

Although the USFS designated these ecosystem services, 

many of the following services are also important for other 

public agencies in the Northern Rockies region:

Provisioning ecosystem services.

• Abundant fresh water for human (e.g., municipal and 

agricultural water supplies) and environmental (e.g., 

maintaining streamflows) uses

• Building materials and other wood products

• Mining materials

• Forage for livestock

• Fuel from firewood and biofuels

• High air quality and scenic views

• Genetic diversity and biodiversity

Regulating ecosystem services:

• Water filtration and maintenance of water quality 

associated with drinking, recreation, and aesthetics

• Protection from wildfire and floods

• Protection from erosion

• Carbon sequestration

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region
436 USDA Forest Service RMRS-GTR-374. 2018

Cultural ecosystem services:

• Recreation opportunities

• Aesthetic values from scenery

• Protection and use of cultural sites

• Native American treaty rights

The amount of detail presented for these ecosystem 

services varies as a function of how much information is 

available and can be interpreted in the context of climate 

change. Many of the ecosystem services are also discussed 

in other chapters of this assessment, including recreation 

(Chapter 10), genetic diversity and biodiversity (Chapter 6), 

protection from wildfire and floods (Chapter 9) and cultural 

resources (Chapter 12). Most of the others are covered 

to some extent in this chapter. Ecosystem services are 

combined in a single section if all of them are likely to be 

affected by the same changes in natural resource conditions.

Social Vulnerability and 

Adaptive Capacity

Communities that have the social structure and resources 

to adapt to one environmental impact generally have the 

capacity to adapt to others. A growing literature on social 

vulnerability seeks to identify which institutions, resources, 

and characteristics make communities more or less resilient 

to environmental hazards. This discussion addresses the first 

part of social vulnerability—exposure to negative changes 

related to specific ecosystem services and possible adaptation strategies. The capacity to adapt to those changes often 

depends on factors that transcend specific resources, so 

capacity is addressed more broadly here.

 The most widely used measure of social vulnerability is 

the Social Vulnerability Index (SoVI), managed and updated 

by the Hazards and Vulnerability Research Institute at the 

University of South Carolina (Cutter et al. 2003). The SoVI 

is based on 11 underlying factors identified to affect social 

vulnerability: personal wealth, age, density of the built environment, single-sector economic dependence, housing stock 

and tenancy, race, ethnicity, occupation, and infrastructure 

dependence. For each county in the United States, scores 

based on these 11 factors are summed to form a composite 

vulnerability score. To highlight counties with the most 

“extreme” scores, composite scores are then converted to 

standard deviations and mapped (fig. 11.1).

Figure 11.1 shows that most counties in the region fall 

in the high to medium vulnerability range. A large factor 

in the region’s vulnerability is its rural character. Among 

the region’s counties, the average proportion of county 

populations living in rural areas is 75.3 percent, compared 

to a national average of 19.3 percent (all demographic data 

in this section are based on the 2012 Census American 

Community Survey). Rural counties tend to be reliant on 

a single industry, have older populations, and have fewer 

social resources (e.g., hospitals) than urban areas. Loss of 

youth is also a primary concern among ranching communities, where the younger generation is often reluctant to take 

over the ranching business and more likely to move outside 

the region. The oldest mean average age in the region is 

found in Prairie County, Montana, where the mean age is 

56. The average median age among the counties is 43.4, and 

the low is 22 in Madison County, Idaho. Figure 11.2f shows 

the proportion of each county over the age of 65. An aging 

population and decline in youth in rural counties worries 

many because of the potential loss of a traditional culture in 

many Western communities.

The median household income of Region 1 counties 

is $45,235, which is considerably lower than the national 

average of $53,046. The high-income counties tend to be 

in the eastern part of the region, with ties to the oil and gas 

industry, and areas with high concentrations of recreationbased industries. Income is lowest in the counties dependent 

on grazing and timber.

Figures 11.2a and 11.2b show relatively widespread 

unemployment and poverty in the region. Theodossiou 

(1998) found employment is more important than income in 

predicting life satisfaction. The region on average had an average unemployment rate in 2012 of 5.4 percent, which was 

lower than the national average of 9.3 percent. Spatially, unemployment follows median income closely, with counties 

in the east having low unemployment and counties in the 

west having high unemployment. A few counties have very 

high unemployment, particularly in the timber-dependent 

counties where jobs are concentrated among a few large 

employers.

The service industry typically pays low wages, maintains 

part-time positions, and does not pay benefits like retirement 

and health insurance. Employment fluctuates with overall 

economic conditions. For these reasons, workers in the 

service industry can be vulnerable to economic fluctuations. 

The mean percentage employed in the region’s service industry is 17.8. In some counties, more than 30 percent of the 

labor force is employed in the service industry.

Many of the factors that make individuals more vulnerable are compounded among migrants and minorities. 

They tend to have fewer economic resources, lack political 

power, and sometimes struggle with communication (fig. 

11.2e) (Aguirre 1998; Blaikie et al. 1994; Fothergill and 

Peek 2004; Morrow 1999; Phillips 1993; Phillips and 

Ephraim 1992). Such factors make minorities less likely 

to participate in disaster planning, be familiar with support 

services, and have basic resources such as a vehicle for use 

during an evacuation or to transport the injured and sick to 

hospitals (fig. 11.2c). On average, the region has very few 

foreign-born residents, 2.7 percent compared to a national 

average of 12.9 percent. But a few counties have large 

concentrations of migrant agricultural workers (fig. 11.2d). 

Clark County, Idaho was home to more than 350 immigrants 

though it had only 982 people in the 2010 census. Minorities 

are also concentrated among a few counties. Between 39 

and 56 percent of the populations in the Idaho counties in 

the region are minorities, compared to a regional average of 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 437

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.1—The Social Vulnerability Index (SoVI) to Environmental Hazards for U.S. Counties (managed and 

updated by the Hazards and Vulnerability Research Institute at the University of South Carolina; Cutter et al. 

2003). The SoVI is based on 11 underlying factors identified to affect social vulnerability: personal wealth, 

age, density of the built environment, single-sector economic dependence, housing stock and tenancy, race, 

ethnicity, occupation, and infrastructure dependence. For each county in the U.S., scores based on these 11 

factors are summed to form a composite vulnerability score. To highlight counties with the most “extreme” 

scores, composite scores are then converted to standard deviations and mapped.

A

B

Figure 11.2—Demographic 

information for the 

Northern Rockies 

region, including (a) 

proportion unemployed, 

(b) proportion in poverty, 

(c) proportion without a 

vehicle, (d) proportion of 

minorities, (e) proportion 

with limited English skills, 

and (f) proportion over 

age 65.
438 USDA Forest Service RMRS-GTR-374. 2018

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.2—Continued.

C

D

E

F

only 15.9 percent. In comparison, many counties in eastern 

Montana and North Dakota have less than 5 percent minorities. The predominant minority group in the region is Native 

American in those counties with more than 56 percent of 

their population from minorities.

Some of the regional trends in vulnerability and demographics are tied to traditional uses of the land and major 

industries in the counties. Table 11.1 shows mean SoVI scores 

by industry. Grazing communities tend to be older, poorer, 

and more rural, so they score significantly higher on the SoVI 

than communities without grazing. Communities dependent 

on timber, oil and gas, and recreation have significantly lower 

SoVI scores than other counties. Counties in the national 

forest economic impact zones of Region 1 have higher SoVI 

scores, though the difference is not significant (table 11.1).

Table 11.2 shows the number of counties significantly 

below or above the regional mean SoVI, by industry. Among 

grazing counties, 54 counties have unemployment rates 

significantly below the regional average of 5.4 percent and 

18 counties have unemployment rates significantly above the 

regional average (based on 95 percent confidence intervals). 

Grazing counties tend to have the lowest median incomes, the 

oldest populations, and the highest percentage of people living in rural settings. Timber counties tend to have the highest 

unemployment rates and the highest percentages of foreignborn residents and minorities. Counties where many people 

have recreation-based employment are among the least 

vulnerable despite high employment in the service industry. 

Counties with oil and gas tend to have lower unemployment 

rates and higher wages than most places in the United States.
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Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.1—Mean Social Vulnerability Index scores across industries. Counties were ranked by industry shares for each industry 

and separated into quartiles. Scores are first (on the left) compared scores for the lower and upper quartiles, then (on the right) 

the lower and upper half of counties, sorted by shares of employment in that industry. Significance levels are shown by the 

test statistics for comparison of the means and the associated p-values.

Lower 

quartile

Upper 

quartile Test statistic P-value Lower half Upper half Test statistic P-value

Timber 2.93 0.94 4.32 0.00 2.90 0.76 5.44 0.00

Grazing -0.20 3.69 -8.03 0.00 0.61 3.04 -6.37 0.00

Recreation 2.56 0.63 3.56 0.00 2.39 1.28 2.67 0.01

Oil & gas 2.45 1.68 1.38 0.17 1.94 1.74 0.47 0.64

Table 11.2—Number of counties significantly below and above regional means. Each row shows data for counties that are in the 

top half of counties sorted by share of employment in that industry. For example, the “Grazing” row shows results for counties 

for which grazing represents a larger share of total employment than half the other counties in the region.

Unemployment 

rate 

(5.4%)

Percent 

employed in 

service industry 

(17.8%)

Median 

household 

income 

($45,235)

Median age 

(43.4)

Percent foreign 

born 

(2.7%)

Percent 

population 

minority 

(15.9%)

Percent 

population 

in rural areas 

(75.3%)

Below Above Below Above Below Above Below Above Below Above Below Above Below Above

Grazing 54 18 44 21 49 24 16 57 57 12 62 15 13 66

Timber 27 40 19 43 43 34 34 39 25 32 57 23 45 29

Recreation 37 36 18 44 41 32 37 36 31 26 59 21 47 31

Oil and gas 54 21 31 34 33 43 32 39 38 25 65 12 37 41

Ecosystem Service: 

Water Quantity

Water use can be broadly classified as consumptive or 

nonconsumptive. Water allocated to a consumptive use 

is not available for other uses, whereas water allocated to 

a nonconsumptive use is available for other uses. Most 

economic uses of water have components of both consumptive and nonconsumptive uses. For example, a portion 

of water applied to croplands is taken up by plants and 

does not return to the waterways; this portion represents 

consumptive use of water by the crop. The portion of water 

applied to cropland that returns to the waterways via runoff 

is the nonconsumptive portion. Major consumptive uses of 

water in the Northern Rockies region include domestic and 

municipal water supply, industrial use of water, and water 

for oil and gas development (drilling and hydraulic fracturing). Nonconsumptive uses of water in the region include 

recreational uses (e.g., boating, maintaining fish habitat) and 

hydroelectric power production. Most water in the Northern 

Rockies is already appropriated, and many uses are tied to 

junior water rights. Junior water rights can be exercised only 

during high-flow years, so they are unreliable from season 

to season or year to year. Any new uses of water require 

a transfer of water rights, increased water supply through 

reservoir storage, or mining of groundwater.

A recent draft of the Montana State Water Plan (Montana 

Department of Natural Resources and Conservation 

[DNRC] 2014) details water use in Montana (tables 11.3, 

11.4) and is representative of most of the Northern Rockies 

region. Hydroelectric power generation (hydropower) accounts for 86 percent of total water demand in Montana, 

although hydropower is considered a nonconsumptive 

use because it does not affect instream flow or total water 

available downstream. However, reservoirs needed for hydropower have high rates of water loss to evaporation. Fort 

Peck Reservoir, in the lower Missouri River basin, annually 

loses 611,400 acre-feet of water to evaporation.

The largest consumptive use of water in Montana is 

irrigated agriculture, which accounts for 96 percent of all 

water diversions and 67 percent of all consumptive use (accounting for return flows). In the Yellowstone River basin, 

irrigation accounts for 83 percent of consumptive use.

Due to the downstream location of fish and wildlife 

habitat, preserving instream water for habitat often requires 

explicit water rights. Montana Fish, Wildlife and Parks 

maintains 3.6 million acre-feet of instream flow rights 

downstream of Fort Peck Reservoir and below the Milk 

River confluence with the Missouri River. The agency 
440 USDA Forest Service RMRS-GTR-374. 2018

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.3—Total water use in Montanaa.

Planning basin

Hydropower 

(non-consumptive) Irrigation

Reservoir 

evaporation

Municipal, 

industrial, livestock

In-stream flow 

(non-consumptive)

Percent

Statewide 86.0 12.4 1.2 0.5 0

Clark Fork / Kootenai River 94.4 4.7 0.5 0.4 0

Upper Missouri 88.0 11.2 0.5 0.3 0

Lower Missouri 39.4 19.5 6.0 0.3 35.0

Yellowstone River 24.5 23.0 0.4 1.4 50.7

a Data from Montana DNRC (2014). 

Table 11.4—Consumptive water use in Montana.a

Planning basin Irrigation

Reservoir 

evaporation

Domestic & 

municipal Livestock Industrial Thermo-electric

Percent

Statewide 67.3 28.0 2.4 1.2 0.3 0.8

Clark Fork / Kootenai River 67.0 27.0 3.9 0.5 1.2 0

Upper Missouri 82.2 13.7 3.0 0.9 <0.1 0

Lower Missouri 42.0 56.3 0.4 1.4 <0.1 0

Yellowstone River 83.3 7.2 2.8 2.1 0.3 4.2

a Data from Montana DNRC (2014).

maintains 5.5 million acre-feet of instream flow rights for 

the Yellowstone River at Sidney. Although population is 

increasing in the Western Rockies and Greater Yellowstone 

Area subregions, water demand for urban uses has not 

increased significantly; even in the most populated regions, 

consumptive use by households is below 4 percent.

The share of any particular water use does not imply 

anything about relative values of water among uses. The 

marginal value of water in agriculture is typically lower than 

the marginal value of water for municipal uses, particularly 

in areas of recent population growth. Prices for municipal 

uses are $290 to $3,145 per acre-foot, whereas prices for 

leased agricultural water diverted for instream conservation 

are $42 to $3,614 per acre-foot (Montana DNRC 2014). In 

general, prices increase for more senior water rights and 

when few other options for obtaining water exist in the 

area. Current rates paid by agricultural users of water from 

Bureau of Reclamation and Montana DNRC facilities are 

$2.32 to $7.50 per acre-foot per year, or a capitalized value 

of $76 to $244 per acre-foot. Accounting for delivery and 

operating costs, the capitalized costs of agricultural water 

range from $189 to $615 per acre-foot.

Effects of Climate Change

A warming climate is expected to cause a transition in 

the form of precipitation from snow to rain (see Chapter 

3), which will affect the timing of water availability (see 

Chapter 4). Warmer temperatures will make drought more 

frequent, despite small increases in precipitation shown in 

some climate models; consequently, overall competition for 

water will increase. This will amplify many of the effects of 

population growth and demographic changes already occurring. Agricultural and municipal users will experience major 

impacts, making it more difficult to allocate instream flows 

for recreation and wildlife.

Agriculture

Timing of snowmelt is a chief concern in the Columbia 

and Missouri Basin headwaters (see Chapter 4). Earlier 

runoff may be out of sync with many of the water rights currently held by agriculture, even as warmer months extend the 

growing season. Future water quantities in North Dakota and 

the eastern plains of Montana are likely to be more variable.

North Dakota has already seen an increase in regional 

temperatures that has brought a mixture of impacts to 

agriculture, the largest industry in the State. Wheat production alone generates $4.5 billion annually in economic 

activity (North Dakota Wheat Commission 2007). Warmer 

temperatures and higher commodity prices have pushed 

wheat and corn production into areas of the State where they 

were not previously grown or where shorter-season varieties 

dominated.
USDA Forest Service RMRS-GTR-374. 2018 441

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Higher temperatures increase plant demand for water, 

contributing to droughts even though the Grassland subregion is expected to see a slight increase in precipitation 

(see Chapter 3). Drier soils and more-intense precipitation 

events may increase flood frequency, leading to increased 

dependence on tile drainage. In 2002, drought cost North 

Dakota $223 million, and heavy rains in 2005 ruined more 

than 1 million acres of cropland and prevented another 1 

million acres from being planted. These heavy rains caused 

$425 million in damage to North Dakota crops, and the 

State’s livestock industry lost $32 million, largely from 

the increased price of feed, which was in short supply 

(Karetinkov et al. 2008). More droughts and intense temperatures may also make plants more susceptible to insect 

pests (Rosenzweig et al. 2000).

Domestic and Municipal Uses

If the frequency of drought and heavy rain events 

increases, they will stress municipal water supply systems 

and built infrastructure. Decreased permeability of soils 

associated with drought conditions will also lead to more 

flash floods, endangering lives and affecting water supply 

systems and infrastructure. In regions with clay soils, increased frequency of drought is already causing sidewalks, 

driveways, and streets to crack. Although the cost of fixing 

one sidewalk one time is relatively small, these persistent 

costs add up and have been shown to cause large financial 

burdens on communities.

Warmer months and growing populations will increase 

demand for both air conditioning and lawn watering. There 

will be a slight decrease in demand for heat, but net household demand for electricity is expected to rise. Therefore, 

demands for water for power generation and other municipal 

uses are expected to increase.

Recreation and Wildlife

The effects of climate change on skiing, boating, and 

fishing are summarized in Chapter 10, and the effects of 

wildfire are described in Chapter 8. Beyond effects mentioned in those chapters, it may become harder to preserve 

instream flows even though demographic changes will increase demand for such preservation. Particularly vulnerable 

habitats include small streams in the mountains and highly 

valued fisheries throughout the Northern Rockies.

Climate models suggest a drier climate will shift some 

of the most productive waterfowl breeding grounds of the 

northern prairie wetlands and pothole region (which produces 50 to 80 percent of ducks in North America) to the wetter 

eastern and northern fringes of the Northern Rockies, an 

area where many wetlands have been drained. Unless these 

wetlands are restored, bird populations will be significantly 

affected (Johnson et al. 2005). Some estimates show that the 

north-central duck population in the United States could be 

reduced by 50 percent (Sorenson et al. 1998).

Adaptive Capacity

As noted earlier, adaptive capacity refers to institutional 

capability to modify management, decisionmaking, and 

policy to ensure sustainable production of ecosystem services. Objectively assessing the capacity of the Northern 

Rockies region to respond to changes in ecosystem services 

is difficult, with little guidance in general from science and 

no guidance specific to the region. This section, therefore, 

mostly focuses on adaptation strategies.

Transfer of water rights from one use to another is legally 

possible within the Northern Rockies region but is realistically constrained by the ability to transport water. Transfers 

between agricultural and municipal uses, for example, can 

occur only between users in the same watershed. Because 

municipal values of water are usually higher than those of 

agriculture, these transfers are likely to occur should the 

need be dire enough.

Reuse of effluent and other conservation methods will 

be important tools for adaptation. Groundwater pumping is 

also available as a short-term solution, but is not sustainable 

in the long run. These methods are expensive and will be 

cost prohibitive for most rural communities in the Northern 

Rockies. New municipal demands are more likely to be 

met by purchasing or leasing reliable senior water rights 

(Montana DNRC 2014). Water rights are still available in 

some water basins, but these new appropriations are junior 

in priority and not likely to be reliable enough for municipal 

uses.

A drier climate in the central and western prairie pothole habitats of the Grassland subregion will diminish the 

benefits of preserving waterfowl habitat in that area and 

increase the importance of restoring wetlands along the wetter fringes (Johnson et al. 2005).

Risk Assessment

Compared to more arid regions of the western United 

States, changes in water yield in the Northern Rockies 

region are expected to be modest, although they may be 

disproportionately large for local residents who experience 

them (Foti et al. 2012). Changes in timing of runoff will 

be significant. Climate and hydrologic models consistently 

project changes in temperature and timing of runoff, making 

the likelihood of these effects high.

Ecosystem Service: Water 

Quality, Aquatic Habitats, 

and Fish for Food

Compared to many areas of the United States, the 

Northern Rockies region has excellent water quality. The 

headwater streams of the region generally provide safe, 

clean drinking water to downstream communities (fig. 11.3) 

and provide habitat for some of the Nation’s premier 
442 USDA Forest Service RMRS-GTR-374. 2018

recreational and commercial fisheries (see Chapter 10). 

Fresh water is important to area tribes’ cultural practices, 

including ability to exercise their indigenous fishing rights. 

Nonetheless, many of the streams and lakes in the region 

are already threatened or impaired according to U.S. 

Environmental Protection Agency standards (tables 11.5, 

11.6, 11.7). In all Northern Rockies States, agriculture is 

the primary source of impairment in rivers and streams; 

impairment results from grazing in riparian and shoreline 

zones and from fertilizer sediment in runoff. In Montana, 

grazing leads to loss of streamside vegetation and increased 

sedimentation. Idaho has similar disturbances, but with 

increased water temperatures as the primary reason for impairment. In North Dakota, animal feeding operations add to 

riparian grazing, causing unsafe levels of fecal coliform and 

habitat alterations.

Major causes of impairment for lakes, reservoirs, and 

ponds differ between States. Runoff from roads and bridges 

is a problem in Idaho, leading to high levels of phosphorus 

and mercury. In Montana, abandoned mines can cause accumulation of mercury and lead. In North Dakota, grazing 

and animal feeding operations can produce levels of fecal 

coliform that can contaminate water bodies.

For municipal water supplies, disturbances such as 

wildfires and mudslides are a major concern (see Chapter 8) 

(fig. 11.4). Due to the generally high water quality in the 

region, water treatment plants are able to operate with 

lower capital investments. When there are sudden increases 

in sediment or other pollutants, such as often occurs after 

a wildfire, treatment plants need to shut down or incur 

high costs to treat the water and remove sediment from 

reservoirs.

Some Northern Rockies residents worry about the 

effects of increased oil and gas extraction activities on watershed health. Groundwater contamination in northeastern 

Montana near the Fort Peck Indian Reservation has been 

linked to development of the East Poplar oilfield (Thamke 

and Smith 2014). Groundwater is the only source of 

drinking water in the area, and contamination has affected 

drinking water quality. Oil spills in the Yellowstone River 

(2011, 2015), a pipeline leak near Tioga, North Dakota 

(2014), and train derailments in Lac Megantic, Quebec 

(2013) and near Lynchburg, Virginia (2014) highlight the 

dangers to watersheds surrounding oil and gas fields, even 

if the activity that caused contamination does not occur in 

the watershed.

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.3—Forests to Faucets data showing the relative importance of surface water for municipal water supply (top) and 

forests for maintaining watershed health (bottom). The index depends on both the amount of water coming off forests and the 

population served by that water. Higher numbers indicate higher levels of importance (from Weidner and Todd 2011).
USDA Forest Service RMRS-GTR-374. 2018 443

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.5—Threatened and impaired waterways in Montana.a

Rivers and 

streams

Lakes, 

reservoirs, 

and ponds

Use Percent

Agriculture 14.3 22.1

Aquatic life 83.6 76.7

Drinking water 29.3 65.5

Primary contact recreation 38.7 13.5

Causes of impairment

Rivers and streams Miles

 Alteration in streamside or 

 littoral vegetation 

8,352

 Sedimentation, siltation 7,456

 Phosphorus 5,091

 Low flow alterations 4,936

 Nitrogen total 4,846

Lakes, reservoirs, and ponds Acres

 Mercury 311,192

 Lead 246,950

 Phosphorous, total 73,324

 Sedimentation, siltation 69,411

 Nitrogen, total 68,354

Sources of impairment

Rivers and streams Miles

 Agriculture 6,000

 Grazing in riparian or 

 shoreline zones 

5,862

 Irrigated crop production 4,570

 Natural sources 4,518

 Source unknown 4,223

Lakes, reservoirs, and ponds Acres

 Impacts from abandoned mine 

 lands 

279,490

 Atmospheric deposition – 

 toxics 

250,570

 Historic bottom sediments (not

 sediment) 

237,654

 Municipal point source 

 discharges 

 97,542

 Source unknown 86,868

0 Data from U.S. Environmental Protection Agency (2016).

Table 11.6—Threatened and impaired waterways in Idaho.a

Rivers and 

streams

Lakes, 

reservoirs, 

and ponds

Use Percent

Cold water aquatic life 52.5 91.3

Primary contact recreation 18.3 2.6

Salmonid spawning 45.9 86.0

Warm water aquatic life 68.0 99.4

Domestic water supply 3.2 0

Seasonal cold water aquatic life 0 100

Secondary contact recreation 15.3 97.0

Causes of impairment

Rivers and streams Miles

 Temperature, water 18,494

 Sedimentation, siltation 14,988

 Phosphorus 6,017

 Escherichia coli 4,480

 Combined benthic, fish 

 bioassessments 

 4,306

 Other flow regime alterations 3,877

Lakes, reservoirs, and ponds Acres

 Phosphorus 146,576

 Mercury 121,329

 Other flow regime alterations 84,682

 Sediment, siltation 80,169

 Dissolved oxygen 77,473

Sources of impairment

Streams and rivers Miles

 Grazing in riparian or shoreline 

 zones

2,230

 Rangeland grazing 1,782

 Livestock (grazing, feeding) 1,152

 Flow alterations from water 

 diversions 

 643

 Loss of riparian habitat 608

 Managed pasture grazing 561

Lakes, reservoirs, and ponds Acres

 Highways, roads, bridges, 

 infrastructure 

340

 Post-development erosion and 

 sedimentation 

340

 Natural sources 340

 Agriculture 340

 Loss of riparian habitat 340

a Data from U.S. Environmental Protection Agency (2016).
444 USDA Forest Service RMRS-GTR-374. 2018

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Effects of Climate Change

Climate change will influence water quality in ways that 

affect fishing, water-based recreation, and drinking water. 

Climate change will amplify the effects of development on 

water quality already occurring in the Northern Rockies 

region. Increased number and severity of wildfires will lead to 

deposition of more sediment in streams, lakes, and reservoirs. 

Increased air temperature and loss of vegetation along stream 

banks will raise the temperature of streams, and altered vegetation may affect water filtration and flow rate. Lower water 

quality may affect municipal water supplies, water-based 

recreation, and ecosystem services tied to the health of fish 

and wildlife and associated aquatic systems.

Warming air temperature due to climate change and loss 

of streamside vegetation due to development, grazing, and 

agriculture in the riparian zone will cause water temperatures 

to increase. Temperature is a significant abiotic factor influencing physiology, bioenergetics, behavior, and biogeography 

because most aquatic organisms are ectothermic (Rahel 

2002; Sweeney et al. 1992). Some native fish species, such 

as bull trout (Salvelinus confluentus), are extremely sensitive 

to warm water, whereas some nonnative species can tolerate 

higher temperatures (see Chapter 5). The biggest and earliest 

temperature increases are likely to occur in fish habitats at 

lower elevations; consequently, these habitats will be the most 

vulnerable to shifts in species composition and distribution. 

The response of microbial and aquatic invertebrate communities to a warming climate and altered hydrologic patterns is 

poorly understood. Native fish species with high ecological 

plasticity will be able to withstand some environmental 

change by altering life history timing or distribution patterns. 

But the magnitude and rate of change will overwhelm species 

with narrow ecological niches or limited ability to withstand 

competition from nonnative species. In the Northern Rockies 

region, these more-vulnerable species include bull trout 

(Salvelinus confluentus) and cutthroat trout (Oncorhynchus 

clarkii).

Effects of climate change on fish are summarized in 

Chapter 5, and effects on recreational fishing are summarized in Chapter 10. Additional effects are likely to occur to 

culturally important fisheries. For example, the Nez Perce 

Tribe maintains fishing rights within the boundaries of its 

reservation and traditional fishing grounds, which include the 

mainstem of the Columbia River. Hydropower and stream 

modification have already significantly affected salmon and 

steelhead (O. mykiss) fisheries (Smith et al. 2002; Wagner et 

al. 2004; Williams et al. 2001). Climate change is expected to 

amplify these impacts, leading to decreased fish abundance 

and increased emphasis on conservation programs.

Threats to municipal watersheds from wildfire and insects are expected to increase considerably (see Chapter 8). 

Climate models project higher precipitation for the region and 

more frequent occurrence of storm events (see Chapter 3). 

These changes will potentially increase sedimentation in rivers and reservoirs, increase water treatment costs, and require 

expensive dredging in reservoirs to maintain water storage.

Table 11.7—Threatened and impaired waterways in North 

Dakota.a

Rivers and 

streams

Lakes, 

reservoirs, 

and ponds

Use Percent

Agriculture 0 0

Fish and other aquatic biota 16.6 0.1

Fish consumption 80.8 81.3

Industrial 0 0

Municipal and domestic 0 0

Recreation 27.2 0.9

Causes of impairment

Rivers and streams Miles

 Fecal coliform bacteria 3,820

 Physical substrate habitat 

 alterations 2,423

 Escherichia coli 1,882

 Sedimentation, siltation 1,783

 Combined benthic, fish 

 bioassessments 604

Lakes, reservoirs, and ponds Acres

 Fecal coliform bacteria 3,820

 Physical substrate habitat 

 alterations 2,423

 Escherichia coli 1,882

 Sedimentation, siltation 1,783

 Combined benthic, fish 

 bioassessments 604

Sources of impairment

Rivers and streams Miles

 Grazing in riparian or 

 shoreline zones 5,797

 Animal feeding operations 3,909

 Crop production (crop land or 

 dry land) 2,549

 Loss of riparian habitat 2,415

 Source unknown 1,148

Lakes, reservoirs, and ponds Acres

 Grazing in riparian or 

 shoreline zones 5,797

 Animal feeding operations 3,909

 Crop production (crop land or 

 dry land) 2,549

 Loss of riparian habitat 2,415

 Source unknown 1,148

a Data from U.S. Environmental Protection Agency (2016).
USDA Forest Service RMRS-GTR-374. 2018 445

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.4—Wildland fire threat to forests and importance to surface drinking water. Higher numbers indicate higher risk of 

wildland fire (from Weidner and Todd 2011).

Warming has already led to expansion of agriculture 

in some areas of the western United States, including the 

Northern Rockies region. Higher precipitation could lead to 

increased dependence on tile drainage and increased levels 

of pollutants in waterways. Increased occurrence of drought 

would have the exact opposite effect. Expansion of agriculture would generally cause reduced water quality, but the 

net effects of both—more flooding and more drought—are 

uncertain (Warziniack 2014).

Many of the effects on water quality will be magnified if 

water quantity also falls substantially. Lower flows have been 

linked to increases in water temperature, eutrophication, and 

increases in nutrients and metals. Lower flows imply less 

water to dissipate solar radiation and dilute pollutants already 

in the water (Allan and Castillo 2007; Murdoch et al. 2000; 

Poole and Berman 2001; van Vliet et al. 2011). Low flows 

also increase the likelihood of eutrophication in nutrient-rich 

bodies of water (Conley et al. 2009; Schindler et al. 2008; 

Vollenweider 1968).

Adaptive Capacity

Restoration of streams, wetlands, and riparian areas may 

help stabilize temperatures in some locations, but in the long 

term, investments in water treatment infrastructure will be 

needed if sediment increases substantially or if large disturbances become more frequent. Enhancing fish populations 

through hatcheries is already occurring, and such human intervention may become more important in the face of climate 

change. Other adaptation strategies for aquatic species and 

water-based recreation are described in chapters 5 and 10.

Risk Assessment

The effects of increased fire frequency on municipal water 

supplies will be large, and are likely to be amplified by an 

increasing population reliant on surface water. Altered timing 

of precipitation and frequency of flooding may affect erosion 

rates (Sham et al. 2013). Given current knowledge gaps about 

the response of a species to climate change, it is difficult to 

provide a quantitative risk assessment. For example, a large 

portion of currently suitable habitat for native trout species 

could disappear in the Northern Rockies region by 2100 

(Isaak 2012). This would be an example of a high-magnitude 

effect for ecosystem services and aquatic species.

The likelihood of effects on municipal water supplies is 

high, and is already occurring in some regions of the western 

United States. Sedimentation from severe wildfires in areas 

where fire has been excluded for many decades may cause 

more impacts than climate change. Nonetheless, climate 

change is expected to exacerbate these effects. Given the 

high levels of diversity and variability in how aquatic habitats 

will respond to a changing climate, it is difficult to quantify 

the likelihood of effects for these ecosystem services. Lowelevation habitats are expected to be affected the most and 

soonest, resulting in a high likelihood for a shift in ecosystem 

services in aquatic systems. High-elevation aquatic environments may be buffered by the influence of altitude on 

temperature, resulting in a lower likelihood of effects, at least 

in the near term.

Ecosystem Service: Building 

Materials and other 

Wood Products

Timber used for wood products is a provisioning ecosystem service. Much of the timber is exported from the 

Northern Rockies region, so the most important aspect of 

timber is its ability to provide jobs, particularly in rural communities. The timber industry also helps maintain a labor 

force capable of doing forest restoration work.

A timber processing area for the USFS Northern Region 

is defined by counties with processing facilities that receive 

timber from counties containing non-reserved timberland in 

the region (primarily located in Idaho north of the Salmon 

River and in Montana) (McIver et al. 2013). Timber processing spans 12 Idaho counties, 26 Montana counties, and 4 
446 USDA Forest Service RMRS-GTR-374. 2018

Washington counties (fig. 11.5). More than 95 percent of 

timber harvested from regional forests is processed by mills 

in northern Idaho and Montana. In 2011, Idaho and Montana 

contained 160 timber processing facilities including sawmills 

(73), house log/log home facilities (42), manufacturers of 

log furniture (18), post and small pole producers (18), cedar 

products producers (4), plywood and veneer plants (4), and 

a utility pole producer. More than 97 percent of timber is 

processed in sawmills, and 91 percent of timber processed is 

from trees with diameters greater than 10 inches. The proportion of timber processed in sawmills is up from 80 percent 

reported in Keegan et al. (2005).

Timber and forest products are dominant economic forces 

in the Northern Rockies region, with forest products (as defined by U.S. Department of Labor, Bureau of Labor Statistics 

[n.d.]) accounting for 23 percent of direct manufacturing 

employment in Montana (McIver et al. 2013) (table 11.8). 

Historically, much of the timber harvested in the area has 

come from national forests, although that share has decreased 

greatly. In 1979, 46 percent of timber harvested in Idaho came 

from national forests; by 2006 that share was only 7 percent 

(Brandt et al. 2012). Table 11.8 shows the sold volume for the 

Northern Rockies for the past two decades. Timber removal 

has varied over time in response to changing market and 

policy conditions, but the past decade has been particularly 

difficult for the timber industry.

Timber harvests have decreased since the late 1980s 

on national forests throughout the Nation due to changing 

economic conditions, environmental policies, and litigation against public agencies. The easily accessible larger 

tree stock has mostly been cut, increasing timber costs and 

decreasing profits. Increased housing starts spurred a slight 

recovery from 2003 through 2005, but the recession that 

followed led to the worst wood products markets since the 

Great Depression (Keegan et al. 2012). Between 2005 and 

2009, employment in the wood products industry declined 29 

and 24 percent in Idaho and Montana, respectively. Most of 

these losses were in the forestry and logging industries, for 

which employment declined 33 and 37 percent in Idaho and 

Montana, respectively (Bureau of Economic Analysis data, 

from Keegan et al. 2012).

Mills in the region are the major employer for some small 

communities, making the effects particularly pronounced in 

a few places. At the height of the downturn in 2008, initial 

unemployment claims in the wood products industry were 

more than 3,400 in 39 mass layoffs. Across the West, there 

were 30 percent fewer mills operating in 2009–2010 than 

in 2004–2005, a 27-percent decrease in timber-processing 

capacity (Keegan et al. 2012).

Timber jobs have generally been declining in the Northern 

Rockies region, whereas nontimber jobs have generally been 

increasing (fig. 11.6). These data include jobs in growing 

and harvesting, sawmills and paper mills, and wood products 

manufacturing. In 1998, there were 17,076 jobs in the timber 

industry, but in 2012, there were only 9,531 jobs, a 44-percent 

decrease. At the same time, nontimber employment increased 

from 287,163 to 350,929 jobs, a 22.2 percent increase. 

The absolute number of timber jobs has declined while the 

number of nontimber jobs has increased, so the proportion 

of employment in timber has decreased substantially, from 6 

percent in 1998 to 3 percent in 2012.

However, regional trends in timber employment differ within the Northern Rockies region (table 11.9). The 

Western Rockies subregion, which includes the Idaho 

Panhandle, Kootenai, and Nez Perce-Clearwater National 

Forests, has the highest proportion of employment in the 

timber industry, accounting for 5 percent of private employment in 2012. Benewah County, Idaho has 32 percent of 

private employment in timber, the highest in the subregion. 

Employment in the timber industry has decreased most in the 

Western Rockies subregion, with 7 of 15 counties (Asotin, 

Washington; Bonner, Idaho; Clearwater, Idaho; Kootenai, 

Idaho; Lincoln, Montana; Pend Oreille, Washington; and 

Sanders, Montana) losing more than half of their timberrelated jobs between 1998 and 2012. Only one county in the 

subregion (Idaho County, Idaho) increased employment in 

the timber industry (18 percent). Some counties in the Central 

Rockies and Eastern Rockies subregions have increased 

employment, but these are counties with a low proportion of 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.5—Primary area where timber is processed from national forests in the U.S. Forest Service Northern Region.
USDA Forest Service RMRS-GTR-374. 2018 447

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.8—Sold timber volumes from national forests in the U.S. Forest Service Northern Region and Greater Yellowstone Area subregion over the last two decades.a

1980 2013 Difference

National Forest

Number 

of sales Sold volume

Inflation 

adjusted 

sold value Sales Sold volume

Inflation 

adjusted 

sold value Sales Sold volume

Inflation 

adjusted 

sold value

Thousand board 

feet Dollars

Thousand board 

feet Dollars Percent

Beaverhead-Deerlodge 630 47,137 1,971,012 845 8,176 59,067 34 -83 -97

Bitterroot 268 42,751 3,883,685 266 8,123 459,684 -1 -81 -88

Bridger-Teton 425 20,141 885,087 627 9,641 150,834 48 -52 -83

Caribou-Targhee 7,347 98,301 7,726,627 743 7,234 93,922 -90 -93 -99

Custer 127 1,653 81,794 292 1,573 18,088 130 -5 -78

Flathead 289 194,340 22,504,836 334 14,797 963,163 16 -92 -96

Gallatin 310 23,575 628,518 551 4,480 44,820 78 -81 -93

Helena 113 21,916 1,451,979 393 3,431 34,000 248 -84 -98

Idaho Panhandle 669 317,157 64,207,103 866 40,180 3,562,340 29 -87 -94

Kootenai 616 175,803 36,705,744 820 35,589 1,820,020 33 -80 -95

Lewis and Clark 277 12,423 134,615 387 2,152 21,160 40 -83 -84

Lolo 367 40,744 2,281,829 597 6,402 298,537 63 -84 -87

Nez Perce-Clearwater 414 255,741 18,881,743 699 44,402 6,567,655 69 -83 -65

Shoshone 307 11,883 198,089 415 7,667 225,075 35 -35 14

a Source: Headwaters Economics (2017).
448 USDA Forest Service RMRS-GTR-374. 2018

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.6—Total jobs in timber and 

non-timber for national forests in the 

U.S. Forest Service Northern Region 

(from U.S. Department of Commerce 

2014). 

Table 11.9—Employment in the timber industry, by county and region, 2012.a

County

Total private 

employment

Timber 

employment

Employment in 

timber (%)

Change in timber employment, 

1998–2012 (%)

All subregions 365,255 9,531 2.6 -44

Western Rockies subregion 112,143 6,511 5.8

Asotin County, WA 4,605 9 0.2 -95

Benewah County, ID 2,130 677 31.8 -25

Bonner County, ID 10,972 401 3.7 -70

Boundary County, ID 2,239 410 18.3 -3

Clearwater County, ID 1,896 358 18.9 -59

Idaho County, ID 3,165 386 12.2 18

Kootenai County, ID 44,080 913 2.1 -52

Latah County, ID 8,398 349 4.2 -11

Lewis County, ID 717 132 18.4 -47

Lincoln County, MT 3,771 191 5.1 -79

Nez Perce County, ID 16,061 1,693 10.5 -13

Pend Oreille County, WA 1,403 83 5.9 -67

Sanders County, MT 1,910 122 6.4 -55

Shoshone County, ID 4,183 94 2.2 -28

Stevens County, WA 6,613 693 10.5 -30

Central Rockies subregion 110,451 2,374 2.1

Flathead County, MT 31,316 977 3.1 -45

Glacier County, MT 2,205 1 0.0 0

Lake County, MT 5,121 119 2.3 -51

Mineral County, MT 895 231 25.8 175

Missoula County, MT 47,885 574 1.2 -69

Powell County, MT 1,024 243 23.7 37

Ravalli County, MT 8,522 220 2.6 -69

Silver Bow County, MT 13,483 9 0.1 125

Eastern Rockies subregion 114,783 595 0.5

Beaverhead County, MT 2,234 9 0.4 -40

Broadwater County, MT 790 178 22.5 78
USDA Forest Service RMRS-GTR-374. 2018 449

jobs in the timber sector, so a small number of new jobs have 

a disproportionate effect.

Effects of Climate Change

Although temperature and precipitation may affect 

vegetation in the Northern Rockies region, the direct effect 

of climate on timber production is expected to be small. 

More important to the timber industry are the economic and 

policy changes that affect demand for forest products and 

timber quotas for national forests. The primary effects of 

climate change on timber will occur through the effects of 

temperature on disturbance and to a lesser extent on growth 

and productivity (see chapters 7 and 8).

The primary sensitivities of timber resources associated 

with climate change are wildfire, insects, and disease. Forest 

growth is expected to be lower in areas that experience 

higher temperature and decreased precipitation (Ryan et 

al. 2008) (see Chapter 7). In addition, warmer winters and 

associated freezing and thawing may increase forest road 

erosion and landslides, making winter harvest more difficult 

and expensive, and potentially reducing the timber supply 

(Karl et al. 2009). Reduced snowpack may promote insect 

or disease outbreaks, although harvests could increase in the 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.9—Continued.

County

Total private 

employment

Timber 

employment

Employment in 

timber (%)

Change in timber employment, 

1998–2012 (%)

Carbon County, MT 2,169 3 0.1 50

Cascade County, MT 29,168 25 0.1 19

Chouteau County, MT 723 4 0.6 0

Fergus County, MT 3,291 9 0.3 -89

Gallatin County, MT 37,409 103 0.3 -59

Granite County, MT 481 47 9.8 -69

Jefferson County, MT 1,679 34 2.0 89

Lewis and Clark County, MT 23,623 48 0.2 129

Madison County, MT 1,943 10 0.5 67

Meagher County, MT 268 4 1.5 -73

Park County, MT 4,394 86 2.0 -28

Powder River County, MT 329 0 0.0 -100

Rosebud County, MT 2,562 0 0.0 -100

Stillwater County, MT 2,683 35 1.3 -58

Sweet Grass County, MT 1,037 0 0.0 -100

Greater Yellowstone Area subregion 26,609 50 0.2

Fremont County, ID 1,429 19 1.3 -75

Park County, WY 9,876 25 0.3 -36

Teton County, WY 15,304 6 0.0 100

Grassland subregion 1,269 1 0.1

Carter County, MT 184 0 0.0 -100

Harding County, SD 402 1 0.2 0

McHenry County, ND 683 0 0.0 0

a Source: U.S. Department of Commerce (2014). 

short term through salvage of dead and dying trees. Climate 

change will result in larger, more frequent fires and a 

longer fire season. Increased fires may increase demand for 

fuels treatments, either through timber harvests or through 

mechanical and manual thinning that uses the timber labor 

force and infrastructure. Although this may affect the availability of harvestable wood products, the overall effect on 

timber-related jobs would be relatively small.

Forest Products (Commercial Use)

The provision of commercial timber from national forests 

could be affected by altered temperature and precipitation. 

Effects on the distribution and abundance of vegetation 

are expected to vary widely by species and location (see 

Chapter 6). Although overall wood production is projected 

to increase, the proportion of sawtimber (combining both 

softwoods and hardwoods) is somewhat larger with climate 

change in all scenarios, species, and regions. This shift in 

product mix reflects the effects of accelerated growth on 

rotation age, which is lengthened in the long term for all 

regions and species. With longer rotations come larger volumes of sawtimber relative to pulpwood (Irland et al. 2001).
450 USDA Forest Service RMRS-GTR-374. 2018

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Although direct effects of elevated temperature on tree 

growth rates can be positive (e.g., through lengthening the 

growing season), associated soil water deficits will probably occur in most locations except in the high elevations. 

Tree responses to soil water deficits vary among species as 

a result of differences in tree physiology and morphology. 

Within species, drought sensitivity of trees is usually largest 

in seedlings. Mortality can result directly from water stress 

or indirectly from insects and pathogens, and vulnerability 

of trees to more frequent outbreaks may increase during 

periods of water deficit (Kardol et al. 2010). Climate-driven 

changes in instream flow are likely to reduce abundance of 

early successional tree species, favor herbaceous species 

and drought-tolerant and late successional woody species 

(including introduced species), reduce habitat quality for 

some riparian animals, and slow litter decomposition and 

nutrient cycling (Perry et al. 2012).

Although direct effects on tree growth will vary by 

species and climate change scenario, one study observed 

that productivity and timber inventories will increase while 

timber prices decrease (Irland et al. 2001), the result of an 

adaptive timber market. Adaptation in U.S. timber and wood 

product markets is expected to offset some potentially negative effects of climate change. In the United States, lumber 

and plywood production increases under all scenarios, and 

pulpwood production decreases under some scenarios. 

Overall, consumers and mill owners would benefit from 

climate change, whereas landowners may have reduced 

economic benefits (Irland et al. 2001).

Markets generally adapt to short-term increases in mortality by reducing prices, salvaging dead and dying timber, 

and replanting new species that are favorably adapted to the 

new climate. Salvage during dieback ranges from 50 to 75 

percent, depending on management intensity. Total benefits 

to producers plus consumers rise in all scenarios considered. 

Market adaptation can reduce or reverse potential forest 

carbon fluxes in the United States (Irland et al. 2001). 

New technologies represent another method of adapting to 

climate change. For example, new adhesives have led to 

new classes of wood panels and composites, which have 

displaced older products. These new products often enable 

the industry to draw on more abundant species of trees 

that are also closer to end-use markets. New technologies 

have also helped mills produce more product value from a 

given tree. If this trend continues, the forest-based economy 

will be more resilient if forest dieback occurs in the future 

(Irland et al. 2001).

Adaptive Capacity

Adaptive capacity will depend on the ability both to 

manage the natural resources (maintaining healthy forests) 

and to adapt to economic forces. Management actions may 

be able to mitigate drought stress and soil water deficits, 

moderating some of the effects of climate change. Land 

managers also have the option to conduct fuels treatments, which help decrease the probability of large, severe 

wildfires, and to salvage burned or insect-killed timber before it loses market value. Timber management can improve 

forest resistance and resilience to stressors in areas identified 

for treatment, usually in the portions of the forest that contain roads. Timber management is a relatively slow process, 

requiring 50 or more years from regeneration to harvest. 

Therefore, timber management cannot respond quickly to 

potential threats; it serves more as a long-term modification 

of forest composition and structure by helping the landscape 

gradually become more resistant and resilient. The wood 

products industry may also be able to adapt to changing 

conditions by using alternative species, changing the nature 

or location of capital and machinery, changing reliance on 

imports or exports, and adopting new technologies (Irland 

et al. 2001). Developing capacity within the industry to take 

advantage of emerging products will be important, though 

the most resilient communities will be those that diversify 

their economic bases, effectively reducing their exposure to 

adverse impacts to the timber industry.

Risk Assessment

In summary, the magnitude of effects for wood products 

is expected to be large, but mostly from nonclimate forces. 

The likelihood of effects is moderate, again from nonclimate 

forces. But it is uncertain how climate will affect forest 

disturbances, which could have a more dominant influence on 

timber supply.

Ecosystem Service: 

Mining Materials

Minerals are provisioning ecosystem services, but their 

primary role in the region is as an economic driver, providing 

jobs and incomes. Mineral development is important throughout the Northern Rockies, but particularly in northeastern 

Montana and northwestern North Dakota. In some counties, 

oil and gas development represents a third of total income 

to residents. According to 2012 IMPLAN data (MIG 2012), 

the percentages of total county income directly from the oil 

and gas sector are: Fallon County, Montana—33 percent; 

Williams County, North Dakota—32 percent; Slope County, 

North Dakota—29 percent; Dunn County, North Dakota—26 

percent; Stark County, North Dakota—23 percent; Mountrail, 

North Dakota—22 percent; McKenzie, North Dakota—21 

percent. Most of this income comes from the Bakken 

Formation, which lies under parts of North Dakota, Montana, 

and Saskatchewan. At full development (about four wells 

per square mile), the formation is expected to be the Nation’s 

largest oilfield (Mason 2012).

The main stressors from oil and gas development are 

effects on other ecosystem services, such as water quality 

(discussed earlier). Traffic from trucks and heavy machinery 

also increases the risk of introducing nonnative species to surrounding rangelands (see Chapter 7).
USDA Forest Service RMRS-GTR-374. 2018 451

Effects of Climate Change

Climate is not likely to directly affect minerals, but it 

is included in this assessment due to its prominence in the 

region and because of its potential to conflict with other 

ecosystem services. Power generation, oil and gas development, and mineral extraction are major users of water. 

Increased mudslides and fires may threaten oil and gas 

infrastructure, which would in turn threaten the ecosystem 

services that are collocated with mineral development.

Regional centers of oil and gas draw people from 

all over the country looking for high-paying jobs. 

Competition for workers in the oilfields causes wages in all 

other sectors of regional economies, including traditionally 

low-wage jobs in the service industry, to rise. If climate 

adversely affects other economic sectors, job opportunities in mining and energy will become more important. 

Climate change could affect the oil and gas infrastructure, 

but nonclimatic drivers will be more important, including 

international prices for oil and gas, national climate policy, 

and regional concerns about threats to watersheds.

Adaptive Capacity

Global economic forces primarily drive the oil and gas 

industry. Oil and gas development potential determines 

where drilling activity takes place, and regional growth 

occurs so quickly that communities respond to rather than 

plan for such development. Adaptive capacity is either 

not applicable to this ecosystem service or limited from 

the perspective of economic development. The most successful mineral-based economies are those that are able to 

collect some of the resource rents from drilling and invest 

them back into the community, extending prospects for 

long-term economic growth (Kunce and Shogren 2005). 

Oil and gas development is subject to booms and busts, 

and the most resilient communities are those that invest 

resource rents into efforts to diversify the economy.

Risk Assessment

Climate change is not expected to have significant 

effects on industries based on extraction of minerals and 

energy. The magnitude of effects is expected to be large 

from nonclimate forces, and the likelihood of effects is 

expected to be moderate from nonclimate forces.

Ecosystem Service: Forage 

For Livestock

The Northern Rockies region contains 158 million acres 

of rangeland. More than 85 percent of these rangelands are 

privately held; 43 percent of rangeland in the USFS Northern 

Region economic impact area is in Montana, which ranks 

third in the Nation, behind Texas and New Mexico, in nonFederal rangeland area. Of the Federal rangeland, 8.5 million 

acres are BLM lands, of which 8 million acres are in Montana 

(USDOI BLM n.d.). A variety of economic uses for rangeland 

exist in the Northern Rockies region, but grazing cattle is 

by far the largest. Almost all counties in the region have 

shares of total income derived from cattle above the national 

average, with some counties in Montana and the Dakotas 

having more than 100 times the national average (MIG 2012 

IMPLAN data).

Cheatgrass (Bromus tectorum) and other nonnative 

plants have become a major nuisance throughout western 

rangelands, significantly reducing usable forage. The Nez 

Perce-Clearwater National Forest assessment (USDA 

FS 2014) states that forage has decreased in some places 

(table 11.10). Human modification has also converted rangeland to other uses (Reeves and Mitchell 2012). Between 1982 

and 2007, Montana lost about 900 acres of rangeland, 3,100 

acres of Conservation Reserve Program land, and 30 acres of 

cropland. This pattern of loss is consistent across the region, 

with the exception of small gains in pasture in Montana and 

Idaho (table 11.11). Rangeland losses in the West have been 

caused by agricultural development (17.0 percent), resource 

extraction (7.4 percent), and residential development (5.8 

percent) with much smaller losses to mixed use, recreation, 

and transportation (Reeves and Mitchell 2012).

Rates of land conversion exceed population growth. 

Nationally, between 1945 and 1992, one additional person 

led to about half an acre converted to urban use; between 

1992 and 1997, the rate reached 1.2 acres per additional 

person (DeCoster 2000). Human modification and fragmentation of rangelands have potential consequences for 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.10—Unsuitable land area in the Christie Creek and Sherwin Creek allotments in the Nez Perce-Clearwater 

National Forest, including forage production reduced from conversion of desirable vegetation to “weedy” 

species.a

Allotment Pasture Unsuitable land area Forage reduced

Acres Animal unit months

Christie Creek Rhett 83 11

Christie Creek 106 11

Deer Creek 151 20

Sherwin Creek Lower Center Ridge 238 32

Total 578 74

a Source: USDA FS (2014).
452 USDA Forest Service RMRS-GTR-374. 2018

the socioeconomic sustainability of rural communities, 

including loss of rural character, loss of biodiversity, 

difficulty in managing interconnected lands for grazing, 

threats to watershed health, limited outdoor opportunities, 

compromised viewscapes, loss of native species, changes 

in disturbance regimes, and increased spread of nonnative 

species.

Effects of Climate Change

Warmer temperatures and increased precipitation are 

expected to increase productivity of rangelands (Reeves 

and Mitchell 2012) (see Chapter 7), and increased regional 

population will lead to fragmentation of rangelands. Arid 

grasslands are likely to show a short-term response in species richness to altered precipitation due to the prevalence 

of annual species (Cleland et al. 2013). Carbon dioxide 

(CO2) enrichment may alter the relative abundance of 

grassland plant species by increasing the production of 

one or more species without affecting biomass of other 

dominant and codominant species. This favored-species 

pathway to species change is the most frequently reported 

mechanism by which CO2 affects grassland communities 

(Polley et al. 2012).

Cattle stocking rates in the Northern Rockies region 

remain at or below current capacity of the land to support 

livestock (Reeves and Mitchell 2012), with few counties 

experiencing forage demand above current forage supply. 

In the long term, longer and wetter growing seasons would 

probably make rangeland more productive. The greatest 

threat to grazing from climate change may be increasing 

rates of spread of nonnative weeds and changes in fire 

regime (Maher 2007). Fire itself makes ranch planning 

difficult. Loss of access to grazing areas, on both private 

and public lands, requires emergency measures such as 

the use of hay, which can financially devastate ranchers 

already operating with thin margins. Across all rangelands, increased fire in the future has the general effect 

of converting more lands to invasive monocultures (e.g., 

cheatgrass, red brome [B. rubens]). Fire also kills shrubs, 

increasing the prevalence of grasses and herbs, which can 

reduce structural and floristic diversity. The net effect is a 

narrowing of options for ranch income diversification (e.g., 

loss of quail [Oreortyx pictus] habitat and loss of Rocky 

Mountain mule deer [Odocoileus hemionus hemionus] 

winter range).

Adaptive Capacity

Human modification of rangelands and associated 

fragmentation are driven by opportunities for economic 

growth, as land is converted to higher value uses. 

Conversion of rangeland to residential development has 

brought new populations, higher incomes, and higher tax 

bases to rural communities, creating what has been called 

the “New West” (Riebsame et al. 1997). During the 1990s, 

67 percent of counties in the Rocky Mountains grew faster 

than the national average (Beyers and Nelson 2000). 

Natural amenities in the Northern Rockies region are often 

touted as an economic asset (Power 1998; Rasker 1993). 

Economic growth without preservation of these assets is 

not likely to be sustainable.

Risk Assessment

The magnitude of effects on rangeland reflected in 

potentially large increases in productivity will be high, 

but given that forage supply exceeds demand, the effect 

on grazing will be small. Effects of invasive species and 

development may be large. The likelihood of effects is 

high, given that change is already being observed and that 

these trends are likely to persist. Loss of rural character is 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Table 11.11—Changes in non-Federal rangeland area, 1982–2007.a

Net change

Historic 

rangeland

Change 

from historic 

rangeland

Rangeland 

threatened 

by residential 

Rangeland Pasture development

Conservation

Reserve

Program

land

Crop 

land

Acres

Thousands of 

acres Percent

Thousands of 

acres

Montana -897.8 671.6 -3,084 -28.8 67,604 -24 28

South Dakota -784.8 -556.2 -245 1.6 45,924 -52 46

North Dakota -507.4 -5.8 -3,034 85.1 43,214 -71 29

Idaho -177.6 103.4 -1,154 94.6 29,763 -20 77

Wyoming 221.0 -178.0 -458 10.0 49,306 -8 13

a Source: Reeves and Mitchell (2012).
USDA Forest Service RMRS-GTR-374. 2018 453

a concern, but it is not likely that the region will become 

heavily urbanized in the foreseeable future.

Ecosystem Service: 

Viewsheds And Clean Air

Air quality is an important ecosystem service that can 

be altered by changes in vegetation composition and tree 

responses to climate change. For example, tropospheric 

ozone (O3), air pollution episodes, plant sensitivity to air 

pollutants, and release of pollen all affect the provision of 

air quality by forests.

The Northern Rockies region generally has exceptional air quality, although a few counties in the region 

regularly have days with poor air quality (American 

Lung Association® 2015), and some areas are subject 

to wintertime inversions that trap air pollutants. During 

these inversions, wood-burning stoves used to heat homes 

become a major source of air pollution. In the summer, 

smoke from wildfires settles in valleys, leading to poor air 

quality. Counties in Idaho are often affected by burning of 

crop residues, and smoke can get trapped or settle into valleys, where it persists until strong winds clear the air. Major 

sources of air pollution in North Dakota include coal-fired 

power plants, oilfield emissions, and vehicle traffic in the 

mineral-rich areas of the State. However, the North Dakota 

topography does not contain any features that would trap 

pollutants, so air quality is generally good throughout the 

State.

A large percentage of Northern Rockies residents are in 

demographic groups (e.g., elderly, poor) that are sensitive 

to poor air quality. Almost 1 in 10 adults in the region have 

asthma (Centers for Disease Control and Prevention 2009). 

As more and more young people leave rural communities 

for more-urban settings, sensitive populations are left isolated in rural areas that often lack the health facilities needed 

to accommodate an aging, ailing population.

Effects of Climate Change

Air quality can decline rapidly during a wildfire, and 

increased frequency of wildfires will affect viewsheds and 

air quality. Extended fire seasons will affect both scenery 

and air quality, with detrimental effects to human health. 

Analyses of the effects of climate change on air pollution 

in general have shown that climate change will increase the 

severity and duration of air pollution episodes (Bedsworth 

2011). Climate change may affect distribution patterns and 

mixtures of air pollutants through altered wind patterns 

and amount and intensity of precipitation. The intensity 

of precipitation determines atmospheric concentration 

and deposition of acidifying compounds, potentially altering frequency and extent of pollution episodes (e.g., O3) 

(Bytnerowicz et al. 2007). By 2050, summertime organic 

aerosol concentration over the western United States is 

projected to increase by 40 percent and elemental carbon by 

20 percent. Higher temperatures accelerate chemical reactions that synthesize O3 and secondary particle formation. 

Higher temperatures, and perhaps elevated CO2 concentrations, also lead to increased emissions by vegetation of 

volatile organic compound precursors to O3 (Kinney 2008). 

In addition to earlier onset of the pollen season and possibly 

higher seasonal pollen loads in response to higher temperatures and longer growing seasons, elevated CO2 itself may 

increase pollen levels in some plant species (Kinney 2008).

Adaptive Capacity

A number of systems are already in place to alert residents when air quality deteriorates. These systems may 

become more common, as will days with poor air quality 

and associated alerts. Adaptation options include limiting 

physical activity outdoors, using air conditioning, and taking 

medications to mitigate health impacts. Tighter restrictions 

on use of wood for heating homes and on agricultural burning can reduce pollutants, and fuels treatments can reduce 

wildfire risk and smoke intensity. These strategies reduce 

exposure and mitigate damages. Many may be possible in 

the long run, but the geographic diversity and rural character 

of the region makes quick adaptation unlikely. The effects 

of poor air quality also fall heaviest on the most vulnerable 

populations, such as the elderly, young, and poor—groups 

that make up much of the rural populations of the region, 

where shortages of health care already exist. These groups 

have little capacity to adapt.

Risk Assessment

The magnitude of effects is expected to be high because a 

large percentage of the population (rural poor and elderly) is 

at risk for health impacts from poor air quality. This percentage will increase as the population ages and young people 

move to urban areas. The likelihood of effects is expected to 

be high because many areas are already seeing diminished 

air quality from increased fires and longer pollen seasons.

Ecosystem Service: 

Regulation of Soil Erosion

A USFS soil management directive (USDA FS 2009) 

identifies six soil functions: soil biology, soil hydrology, 

nutrient cycling, carbon storage, soil stability and support, 

and filtering and buffering. Steep slopes are the key element 

associated with erosion and landslides in mountain landscapes, and open rangeland is susceptible to topsoil loss. 

Erosion and landslides threaten infrastructure, water quality, 

and important cultural sites.

General resource management practices are designed to 

limit erosion and soil impaction, but landslides and erosion 

are still a common problem. Roads and other human activities are the largest source of sediment in most watersheds. 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region
454 USDA Forest Service RMRS-GTR-374. 2018

Landslide-prone areas are generally on slopes greater than 

60 percent with geomorphology and surficial geology sensitive to earth movement. Individual management units in 

public lands may have hundreds of landslides each year.

Loss of soil from farm fields is a problem in the eastern 

part of the Northern Rockies region (Kellogg et al. 1997), 

but best practices in agriculture and range management have 

begun to slow the loss. Soil loss rates still exceed natural regeneration of soil in much of the eastern part of the region, 

and recent expansion of agriculture is likely to make the 

problem worse.

Effects of Climate Change

Soil erosion is tied to many forces on the landscape 

that are affected by climate change. In mountainous areas, 

wildfire and precipitation interact to affect erosion rates. 

Frequency of wildfire, precipitation in the form of rain rather than snow, and intense precipitation events are expected 

to increase (see chapters 3, 4, and 8), a combination that will 

lead to greater erosion and more landslides.

In the eastern rangelands, increased precipitation and 

warmer temperatures may benefit grass productivity and 

limit erosion. However, the same changes that make rangelands more productive also make land more valuable for 

agriculture. Expansion of agriculture is already occurring and 

will increase soil erosion in some areas. A combination of 

increased drought and increased flooding will add to already 

high erosion rates. Erosion rates on rangelands are also likely 

to increase with greater fire prevalence and spread of nonnative species. Erosion is a significant concern for cultural 

sites, and is discussed in more detail in Chapter 12.

Adaptive Capacity

One of the key impacts of soil erosion in mountains is 

its effect on water quality and drinking water treatment 

costs. Without expensive dredging, the usable life of dams 

and reservoirs will shorten, and capital investments will be 

necessary to remove added sediment from drinking water 

sources (Sham et al. 2013). Limiting erosion on rangelands 

can be done with best management practices for agriculture, 

including the use of buffers and limiting activity in sensitive 

riparian areas. In all areas, more-resilient vegetation can be 

used to stabilize soils and support soil formation and nutrient cycling.

Risk Assessment

Landslides and flooding in mountainous areas have the 

potential for large, sudden damage to homes, infrastructure, 

and watersheds. Costs of soil erosion on the plains are high, 

but occur over extended periods of time. The likelihood 

of increased erosion in the mountains is high because it 

depends on natural processes (e.g., fire, flooding) that are 

already changing. If agricultural practices do not change, 

erosion on the plains is also fairly certain. Likelihood of 

effects on the plains could be low if best practices become 

more common in agriculture.

Ecosystem Service: 

Carbon Sequestration

Forests provide an important ecosystem service in the 

form of carbon sequestration, or the uptake and storage of 

carbon in forests and wood products. Carbon sequestration is often referred to as a regulating ecosystem service 

because it mitigates greenhouse gas emissions by offsetting 

losses through removal and storage of carbon. As such, 

carbon storage in forests is “becoming more valuable as the 

impacts of greenhouse gas emissions are becoming more 

fully understood and experienced” (USDA FS 2015).

The National Forest System (NFS) contains 22 percent of 

the Nation’s total forestland area and 24 percent of the total 

carbon stored in all U.S. forests, excluding interior Alaska. 

The management of these lands and disturbances such as 

fire, insects, and disease influence carbon sequestration 

rates. Rates of sequestration may be enhanced through management strategies that retain and protect forest land from 

conversion to nonforest uses, restore and maintain resilient 

forests that are better adapted to a changing climate and 

other stressors, and reforest lands disturbed by catastrophic 

wildfires and other natural events (e.g., mortality following 

windthrow).

The USFS champions the principles of considering 

carbon and other benefits together, integrating climate 

adaptation and mitigation, and balancing carbon uptake 

and storage in a wide range of ecosystem services, some of 

which have tradeoffs. The goal is to maintain and enhance 

net sequestration on Federal forests across all pools and 

age classes through protection of existing stocks and building resilience in stocks through adaptation, restoration, and 

reforestation. Carbon stewardship is an aspect of sustainable land management. It is also important to consider that 

carbon estimates are most useful at larger spatial scales; 

typically, baseline carbon estimates at the forest scale are 

not useful for project-specific applications.

Forests are highly dynamic systems that are continuously repeating the natural progression of establishment, 

growth, death, and recovery, while cycling carbon throughout the ecosystem and the atmosphere. This cycle, which 

drives overall forest carbon dynamics, varies geographically and by forest type, but also depends on the frequency, 

magnitude, and type of disturbance events. Natural and 

anthropogenic disturbances can cause both immediate and 

gradual changes in forest structure, which in turn affect 

forest carbon dynamics. For instance, a severe wildfire 

may initially release CO2 to the atmosphere and cause tree 

mortality, shifting carbon from living trees to dead wood 

and the soil. As the forest recovers, however, new trees 

establish and grow, absorbing CO2 from the atmosphere. 

Although disturbances may be the predominant drivers of 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 455

forest carbon dynamics (Pan et al. 2011), environmental 

factors, such as the availability of key forest nutrients (e.g., 

CO2 and nitrogen), as well as climatic variability, influence 

forest growth rates and consequently the cycling of carbon 

through a forest ecosystem (Pan et al. 2009).

Changes in carbon stocks and resulting net emissions 

may be influenced through vegetation management strategies. Land management and restoration strategies, plans, 

and actions, such as fire and fuels management, timber 

harvesting, reforestation, and other forest stand treatments, 

can be designed to integrate carbon sequestration capacity 

across broad landscapes and over the long term, while 

meeting other resource management objectives.

Wood uses for products can also complement land 

management by extending the storage of carbon in useful 

products and reducing emissions as wood products substitute for those that emit more CO2 and other greenhouse 

gases. Harvested wood products (HWP), such as lumber, 

panels, and paper, can account for a significant amount of 

offsite carbon storage and estimates of this addition are 

important for both national-level accounting and regional 

reporting (Skog 2008). Products derived from the harvest 

of timber from the national forests extend the storage of 

carbon or substitute for fossil fuel use, both of which are 

part of the overall carbon cycle.

Baseline Estimates

The USFS 2012 Planning Rule and the Climate Change 

Performance Scorecard element 9 (Carbon Assessment and 

Stewardship) require NFS units to both identify baseline 

carbon stocks and to consider that information in planning 

and management. The Office of Sustainability and Climate 

facilitated work by USFS Research & Development to 

develop a nationally consistent carbon assessment framework and to deliver forest information for every NFS unit. 

Estimates of total ecosystem carbon and stock change 

(flux) have been produced at the forest level across the 

Nation, relying on consistent methodology and plot-level 

data from the USFS Forest Inventory and Analysis program (USDA FS 2015).

Carbon stocks reflect the amount of carbon stored in 

seven ecosystem carbon pools—aboveground live tree, 

belowground live tree, understory, standing dead trees, 

down dead wood, forest floor, and soil organic carbon—for 

1990 to 2013. Carbon stock change (flux) reflects the yearto-year balance of carbon going into or being pulled from 

the atmosphere (Woodall et al. 2013). Carbon stock change 

measures the interannual change in carbon stock caused by 

tree growth, disturbance, management, and other factors. 

Negative stock change values indicate that carbon is being 

pulled from the atmosphere (i.e., net carbon sink); positive values mean carbon is being released (i.e., net carbon 

source).

Figure 11.7 displays carbon stock trends for each of the 

national forests in the Northern Region between 1990 and 

2013.The Idaho Panhandle National Forest stored the largest amount of carbon in the region, about 207 million short 

tons in 1990 and 202 million short tons in 2013. During 

this period, the Beaverhead-Deerlodge, Kootenai, Nez 

Perce, Flathead, Lolo, Clearwater, Gallatin, and Custer 

National Forests all increased in ecosystem forest carbon 

stocks, while the Lewis and Clark, Helena, and Bitterroot 

National Forests and Dakota Prairie Grassland decreased.

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.7—Total forest ecosystem carbon for national forests and grassland in the Northern Region from 1990 to 2013. 
456 USDA Forest Service RMRS-GTR-374. 2018

The volume of cumulative carbon stored in Northern 

Region HWP rose sharply in 1955 and began to continually increase at a steady rate, peaking in 1995 with about 

37 million short tons in storage (fig. 11.8). The HWP pool 

since then has decreased to 35 million short tons. This illustrates the influence of timber harvest on the HWP pool. 

The amount of HWP carbon entering that pool is less than 

the amount of carbon exiting it through various pathways, 

so HWP stocks are decreasing.

Effects of Climate Change

Many factors affect the capacity of forests to sequester 

carbon, and the net effect of climate change on carbon 

storage in forests is uncertain. The greatest vulnerability to 

forest distribution and health as a result of climate change 

is increased risk of fire, insects, and disease (mostly fungal 

pathogens). Preliminary results from the Forest Carbon 

Management Framework (Healey et al. 2014; Raymond 

et al. 2015), show, for example, that fire had the largest 

impact on carbon storage on the Flathead National Forest 

between 1990 and 2012, followed by harvest. The largest 

impact on carbon storage on the Idaho Panhandle National 

Forest was disease, followed by harvest.

Nitrogen often is a limiting nutrient in forests, so 

nitrogen deposition may increase wood production and 

accumulation of soil organic matter, thus increasing carbon 

sequestration. When carbon uptake is caused by increased 

growth, it is likely to be a transitory phenomenon. When 

soil accumulation is the primary cause of carbon uptake, 

forests could be a long-term carbon sink because belowground carbon has longer turnover times than aboveground 

carbon (Bytnerowicz et al. 2007).

Tropospheric O3 damage in sensitive plant species may 

offset some productivity gains from elevated atmospheric 

CO2, thus reducing carbon storage on land and possibly 

contributing further to climate change. Increasing O3 will 

negatively affect plant productivity, reducing the ability 

of ecosystems to sequester carbon and indirectly providing feedback to atmospheric CO2 (Sitch et al. 2007). Net 

carbon uptake by terrestrial ecosystems during the 21st 

century is likely to peak before mid-century and then 

weaken or even reverse, thus amplifying climate change 

(IPCC 2007).

Fungal pathogens, especially various types of root rot, 

are another key concern for forests and may affect the 

ability of forests to sequester carbon (Hicke et al. 2012). 

Increased temperature and humidity coupled with decreased snow and cold weather facilitate the spread of root 

rot. As more trees die and decompose, forests could switch 

from carbon sinks to carbon sources.

Adaptive Capacity

Adaptive capacity for sequestering carbon depends 

on the spatial and temporal scales at which an ecosystem 

service is defined. Carbon storage in any particular forest 

location may go up or down over time, but analysis of 

storage should occur at very large spatial scales. Adaptive 

capacity for this ecosystem service is probably low as most 

of the factors affecting carbon sequestration are external, 

including development pressures and wildfire.

Risk Assessment

Although increased temperature and drought will 

reduce forest growth, the most detrimental effects to 

carbon sequestration will be indirect, through increased 

risk and frequency of wildfires and insect outbreaks. Some 

deterioration in forest health is highly likely, so some 

change in the ability of forests to sequester carbon is also 

likely. However, the net effects on forest health and carbon 

sequestration are difficult to project, primarily due to the 

uncertainty in the magnitude of future occurrence of wildfire and insect outbreaks.

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region

Figure 11.8—Cumulative total 

carbon stored in harvested wood 

products (HWP) manufactured 

from Northern Region timber. 

Carbon in HWP includes both 

products that are still in use and 

carbon stored at solid waste 

disposals sites (SWDS), including 

landfills and dumps (Stockmann 

et al. 2014).
USDA Forest Service RMRS-GTR-374. 2018 457

Ecosystem Service: Cultural 

and Heritage Values

The goods and services that ecosystems provide have 

spiritual, cultural, and historical value to many people. The 

effects of climate change will affect the provision of these 

services for individual locations, plant and animal species, 

and landscape characteristics. The majority of research 

on this topic pertains to forest resource values realized by 

Native American tribes and the effect of climate change on 

sense of place (see Adger et al. 2013 for a review).

Availability of resources (e.g., for food) and adequate 

habitat limit traditional lifeways, especially if the distribution and abundance of plants and animals change in 

response to increased temperature and disturbance (especially wildfire). In general, cultural and heritage values are 

high in the Northern Rockies region, and mostly threatened by changes in culture and the way humans interact 

with the landscape. Tribal values face ongoing stresses as 

Native American people attempt to preserve both culture 

and places on the land. Sources of stress range from legal 

struggles with Federal agencies (for example, the ongoing 

disagreement between the Blackfeet and Glacier National 

Park about access to resources on the park) to effects of 

recreation on sacred places. Educational programs and 

law enforcement on Federal lands protect many cultural 

sites, but funding is insufficient to protect all of them (see 

Chapter 12).

A large part of one’s culture is his or her connection 

with physical places, often including an image of “home.” 

The sense of place may be at risk to climate change effects if those connections and images change as a result of 

a changing climate. People may identify with livelihoods 

and activities that are no longer sustainable in a changing 

climate (Adger et al. 2011; Agyeman et al. 2009; Igor 

2005). People who are tied to their communities are more 

reluctant to leave during economic and social hard times, 

which makes them more vulnerable to the effects of climate change (Field and Burch 1988).

Effects of Climate Change

Increased frequency of wildfire, floods, nonnative 

species establishment, and erosion all put cultural values, 

cultural sites, and historic sites at risk. Changes in climate 

that influence ranges of species which are traditionally 

harvested by Native Americans affect the ability of tribes 

to exercise their treaty rights. Impacts can be amplified or 

mitigated by management decisions and societal forces.

The economies of resource-dependent communities 

and indigenous communities in the region are particularly 

sensitive to climate change, with likely winners and 

losers controlled by effects on important local resources 

(Maldonado et al. 2013). Residents of high-elevation and 

northern-latitude communities are likely to experience 

the most disruptive impacts of climate change, including 

shifts in the range or abundance of wild species crucial to 

the livelihoods and well-being of indigenous people (Field 

et al. 2007). As traditional foods are affected by climate 

change through habitat alterations and changes in the 

abundance and distribution of species, traditional practices and knowledge tend to erode (Cordalis and Suagee 

2008; Lynn et al. 2013). Tribal rights to harvest culturally 

important plants, animals, and fish are based on historical 

harvest areas, so tribes may lose their ability to exercise 

these rights if species leave their historical ranges.

Adaptive Capacity

This ecosystem service relates to preserving the past 

and maintaining access to current sites; thus, adaptive 

capacity is low. Increased resources for law enforcement 

and preservation of cultural sites can mitigate some of the 

expected damage, and traditional ecological knowledge 

has helped tribes adapt to past social and ecological periods of change. Fish hatcheries and other human assistance 

to survival of plant and animal species will become more 

important. Vegetation management can potentially be 

implemented near high-risk cultural and historic sites that 

are prone to fire, floods, nonnative species establishment, 

and erosion.

Risk Assessment

Loss of sacred places and heritage is largely irreversible, 

and many argue that the damage associated with such losses 

cannot be quantified. The overall magnitude of climateinduced changes may be moderate to high. Increased rates 

of erosion are already being observed at some cultural sites, 

and vandalism rates are increasing as human population increases. Culturally important fish populations are declining 

and in some cases rely on human assistance for migration 

and survival. Therefore, the likelihood of climate change 

effects is high.

Summary

Ecosystem services are the benefits people derive from 

landscapes and encompass the values that motivate people 

to live in the Northern Rockies region. Ecosystem services 

are the core of our sense of place and are important to 

protect in the face of a growing number of threats. Some of 

these threats are social (demographic changes, economics, 

policy) and some are environmental (e.g., climate change). 

In many cases, social and environmental forces will act to 

amplify the effects of the other, but opportunities exist for 

adaptation in some cases. Below are key findings from the 

ecosystem services vulnerability assessment.

• Total annual water yield is not expected to change 

significantly. However, timing of water availability is 

likely to shift, and summer flows may decline. These 

changes may result in some communities experiencing 

Chapter 11: Effects of Climate Change on Ecosystem Services in the Northern Rockies Region
458 USDA Forest Service RMRS-GTR-374. 2018

summer water shortages, although reservoir storage 

can provide some capacity. Snowmelt is already 

occurring earlier, and both floods and drought may 

become more common. Agriculture is currently the 

largest consumer of water and one of the largest 

economic forces in the region, and rural agricultural 

communities will be disproportionately affected by 

climate change.

•	 Water quality is closely tied to water yield. 

Increased occurrence of wildfires and floods will add 

sediment to rivers and reservoirs, affecting instream 

water quality and making water treatment more 

expensive. Agriculture is currently the major source of 

impairment, leading to loss in streamside vegetation, 

loss of aquatic habitat, increased water temperatures, 

and high levels of fecal coliform. Climate change is 

expected to amplify these effects.

•	 Wood products provide jobs in the region. Climate 

changes will lead to more wildfires and insect 

outbreaks, but in general effects will be small. The 

largest effects on wood products are likely to be from 

economic forces and policies. Timber production 

has been in steady decline, and that trend is likely to 

continue. Timber is a major employer in some small 

towns that have already seen an economic downturn, 

a trend that may continue as a function of economic 

factors at national to local levels.

• The Northern Rockies region contains one of the 

largest oilfields in the United States. Near the Bakken 

formation, about a third of regional income comes 

directly from oil and gas. Minerals and mineral 

extraction are not likely to be affected by climate 

change, making mining and energy development 

important economic drivers. The greatest effect on 

mineral and energy extraction is likely to be how it 

connects to other ecosystem services, particularly 

water quality. Wildfires, floods, and mudslides all put 

mineral extraction infrastructure in danger, which in 

turn increases risk to watersheds.

• Climate change is expected to increase the potential of 

rangeland to provide forage for livestock. Ranching 

and grazing, all else being equal, may benefit from 

climate change. Major threats to grazing are human 

induced, including loss of rural population, spread of 

nonnative grasses, and fragmentation of rangelands.

•	 Viewsheds and air quality will be affected by 

increasing wildfires and longer pollen seasons. A 

growing percentage of the region’s population will 

be in at-risk demographic groups who will suffer 

respiratory and other medical problems on days with 

poor air quality.

• The ability to regulate soil erosion will be diminished 

by agricultural expansion, spread of invasive plants, 

and increased frequency of wildfire and floods. 

Increased capital investments may be needed for water 

treatment plants if water quality degrades significantly. 

Best practices in agriculture and construction of roads 

can mitigate some of these effects.

• The ability of forests to sequester carbon may be 

affected by wildfires, insect outbreaks, and plant 

disease; carbon sequestration in the western part of 

the Northern Rockies region will be affected by more 

frequent disturbance and stress. Managing forests 

for carbon sequestration is likely to become more 

important in response to national climate policies.

• Disturbances such as wildfires, floods, and soil erosion 

place cultural and heritage values at risk. Damage 

to cultural and historic sites is irreversible, making 

protection a key management focus. Climate-induced 

changes in terrestrial habitats and human modification 

of streamflow affect abundance of culturally important 

plants and animals (especially native fish), affecting 

the ability of Native American tribes to exercise their 

treaty rights. Effects on this ecosystem service are 

amplified by social forces that include a growing 

regional population, vandalism, and loss of traditional 

practices in a globalizing culture.

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462 USDA Forest Service RMRS-GTR-374. 2018

Background and Cultural 

Context in the Northern 

Rockies Region

People have inhabited the Northern Rocky Mountains 

of the United States since the close of the last Pleistocene 

glacial period, some 14,000 years B.P. (Fagan 1990; 

Meltzer 2009). Evidence of this ancient and more recent 

human occupation is found throughout the Forest Service, 

U.S. Department of Agriculture (USFS) Northern Region 

and the Greater Yellowstone Area, hereafter called the 

Northern Rockies region. Each of the five subregions, and 

the public and private lands they now encompass, contains 

thousands of years of human history.

The Northern Rockies region is the ancestral homeland or aboriginal territory of the Arikara, Assiniboine, 

Bannock, Blackfeet, Chippewa-Cree, Coeur d’Alene, 

Crow, Hidatsa, Kiowa, Kootenai, Mandan, Nez Perce, 

Northern Cheyenne, Pend d’Oreille, Salish, Shoshone, 

Sioux and other Plains, Intermountain, and Columbia 

Plateau American Indian Tribes (DeMallie 2001; Schleiser 

1994; Walker 1998). Beginning in the 18th century, the 

region was explored and then settled by people of French, 

British, Irish, Scottish, Chinese, German, Scandinavian, 

and other ancestries (White 1993). The region then, as 

today, was a diverse blend of cultural backgrounds and 

lifeways.

The archaeological and historical evidence of these 

past cultural groups, interactions, and events—collectively 

called cultural resources—is extensive and varied across 

the Northern Rockies region. Cultural resources here 

include (1) ancient Indian camps and villages, rock art, 

tool stone quarries, and travel routes; (2) historic military 

forts and battlefields, mining and logging ruins, and homesteads; and (3) ranger stations, fire lookouts, and recreation 

sites built by the Civilian Conservation Corps. Currently, 

some 20,000 cultural resources have been documented, 

which represent probably only a small fraction of what exists in the Northern Rockies region.

Protection of cultural resources has been formally recognized since 1906, when the Antiquities Act was signed 

into law. This law requires Federal land management 

agencies to preserve historic, scientific, commemorative, 

and cultural values of archaeological and historic sites 

and structures of public lands for present and future 

generations (NPS 2015a), and gives the President of the 

United States authority to designate national monuments 

as a means to protect landmarks, structures, and objects 

of historical or scientific significance. The importance of 

cultural resources has been reaffirmed through the Historic 

Sites Act of 1935, the National Historic Preservation Act 

of 1966, the Archaeological Resources Protection Act of 

1979, and the Native American Graves Protection and 

Repatriation Act of 1990. Although the focus of these laws 

differs, together they mandate the protection and management of cultural resources in Federal lands. The National 

Park Service has a particularly strong emphasis on protection of cultural resources (box 12.1).

Beyond physical sites, structures, and artifacts associated with past human use or events, protection of cultural 

resources involves the ongoing use of resources and associated activities relevant to the continuation of specified 

extant cultures. Many cultural resources are currently 

vulnerable to natural biophysical phenomena and human 

activities. Wildfire and biological processes degrade and 

destroy cultural resources, particularly those made of wood 

or located in erosion-prone environments. Vandalism, illegal artifact digging, arson, and other depreciative human 

behaviors also damage cultural resources. Agency land 

management actions can affect cultural sites and landscapes, and although Federal land managers protect and 

mitigate adverse effects to cultural resources, the enormity 

of this task often outstrips agency resources and capacity.

Broad-Scale Climate Change 

Effects on Cultural Resources

This assessment of the potential effects of climate change 

on cultural resources in the Northern Rockies region is fairly 

general because so little information has been generated 

on this topic, compared to the effects of climate change on 

natural resources. The broad diversity of cultural resources 

and locations where they are found makes it difficult to infer 

the spatial extent and timing of specific effects. Therefore, 

we have synthesized the relevant literature from diverse 

disciplines to cautiously project how an altered climate, both 

Chapter 12: Effects of Climate Change on 

Cultural Resources in the Northern Rockies 

Region

Carl M. Davis
USDA Forest Service RMRS-GTR-374. 2018 463

directly and indirectly (through increased disturbance), will 

create conditions that modify the condition of and access to 

cultural resource sites and their contents.

Climate change has the potential to exacerbate and accelerate existing effects to cultural resources (table 12.1). A 

warmer climate will alter the scale of wildfires across western North America (Schoennagel et al. 2004; Westerling et 

al. 2006) (see Chapter 8), thus having at least three general 

effects on cultural resources. First, wildfires readily burn 

cultural resources made of wood and other combustible materials, such as ancient aboriginal wood shelters and game 

drives, or historic homesteads, mining ruins, and buildings. 

Second, emergency wildfire suppression tactics, including 

fireline construction using heavy equipment, affect both 

standing structures and archaeological sites buried in forest 

soils. Third, post-wildfire flooding and debris flows threaten 

cultural resources exposed atop fire-charred landforms and 

soils. Alternatively, fire can expose cultural sites that might 

not have been otherwise visible (fig. 12.1).

Currently, Federal agencies implement various actions 

to reduce the effects of wildfire on cultural resources, such 

as encasing historic structures in fireproof wrap, routing of 

fireline away from sites, and armoring cultural resources 

vulnerable to postfire flooding events. However, these actions are often not commensurate with the scale of large 

wildfires or the ensuing cultural resource loss. Thus, damage 

Box 12.1—National Park Service Lands in the Northern Rockies Emphasize Preservation and 

Management of Cultural Resources

The National Park Service was created by Congress through the National Park Service Organic Act of 1916, whereby 

the Agency would allow “access to parks for the public enjoyment of cultural resources while ensuring their protection” 

(NPS 2011b). Specifically, a cultural resource is considered to be “an aspect of a cultural system that is valued by 

or significantly representative of a culture, or that contains significant information about a culture” (NPS 2015b). 

Cultural heritage and its preservation are emphasized in the agency’s Cultural Resources, Partnerships and Science 

directorate, with goals to:

• Preserve cultural resources in cooperation with Indian tribes, Alaska Native villages and corporations, Native 

Hawaiian organizations, States, territories, local governments, nonprofit organizations, property owners, 

individuals, and other partners.

• Provide leadership in research and use of advanced technologies to improve the preservation of the nation’s 

cultural heritage.

• Establish standards and guidance for managing cultural resources within the National Park System and 

communities nationwide.

• Enhance public understanding and appreciation for the Nation’s cultural heritage. 

Cultural Resources of National Parks in the Northern Rockies

Glacier National Park

Glacier National Park has six National Historic Landmarks and 350 structures listed in the National Register of Historic 

Places. Archaeological resources found in the park include prehistoric campsites, mining claims, and homesteads. 

Cultural landscapes in the park include the Going-to-the-Sun-Road, Chief Mountain, and Headquarters Historic District. 

Grand Teton National Park

Historical sites in Grand Teton National Park predate creation of the park, and many structures are found in the National 

Register of Historic Places. Some of these structures are remnants of homesteads of ranchers and other people who 

settled in the Jackson Hole area. Several of these structures have been incorporated into the park and restored to 

their original condition. An example of an early structure preserved in the park is Mining Ditch, which carried water 

near Schwabacher’s Landing. Cunningham Cabin, home to early settlers in the Jackson Hole area, has also been 

preserved. Menor’s Ferry operated for decades until 1927, taking passengers across the Snake River, and is now part 

of a Historic District that was recently added to the National Register. 

Yellowstone National Park

Yellowstone National Park has been preserved not only for biodiversity but also for information about past human 

activities and significant archaeological and cultural resources contained within the park. Some historic structures 

and sites are Obsidian Cliff, where obsidian was first used for making tools more than 11,000 years B.P.; Yellowstone 

Lake, which has intact cultural deposits from more than 9,000 years B.P.; Mammoth Hot Springs, which includes the 

Mammoth Post Office and Roosevelt Arch from the late 1800s; and the town site of Cinnabar, Montana, which was 

established in 1883 as the last stop on the Northern Pacific Railroad line to Yellowstone Park. The potential effects of 

climate change on cultural resources have been described for Big Hole National Battlefield, Montana (NPS 2011a). A 

warmer climate will complicate the goal of management to restore and maintain the battlefield in a biological condition 

representative of 1877. Scientific understanding of climate change effects provides a foundation for reconciling 

biological effects with management goals based on historical conditions.

Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
464 USDA Forest Service RMRS-GTR-374. 2018

is expected to continue as climate change amplifies amount 

of area burned, if not severity, across the Northern Rockies 

region.

Seasonal aridity and prolonged drought accelerate soil 

deflation and erosion, and thus expose archaeological sites 

once buried in plains and mountain soils. Wind and water 

roil across archaeological sites, blowing or washing away 

ground cover, revealing ancient artifacts and features such 

as cooking hearths and tool-making areas (fig. 12.2). Newly 

exposed ground leaves artifacts vulnerable to artifact collecting and illegal digging, effects that are intensified in 

areas where livestock grazing, recreation, and mining occur 

and the ground is already impacted. For example, livestock 

in grazing allotments typically converge around creeks and 

natural springs where ancient hunter-gatherer archaeological 

sites are commonly located.

Periods of dry climate and drought have occurred 

throughout the Holocene in the Intermountain West, with 

corresponding episodes of soil deflation, erosion, and 

down cutting (Meltzer 1990; Ruddiman 2007). However, 

increasing temperatures outside of the Holocene norm 

(Intergovernmental Panel on Climate Change 2007; 

Mayewski and White 2002; see also Chapter 3) will create additional potential for cultural resource loss through 

drought and erosion, particularly in drier areas such as 

southeastern Montana.

In addition, if winter precipitation increases (see Chapter 

3) and reduced snowpack leads to higher winter streamflows 

(see Chapter 4), archaeological and historic sites will be 

increasingly vulnerable to flooding, debris flows, down 

cutting, and mass wasting of underlying landforms. This 

scenario is now common in the aftermath of large-scale 

wildfires, especially in the dry mountain ranges of central 

Table 12.1—Summary of climate change stressors and potential effects on cultural resources in the Northern Rockies (see also 

Rockman 2014, UNESCO 2007). Human activities can exacerbate some of the expected effects of climate change (see text).

Climate change 

stressor Biophysical effects Effects on cultural sites and landscapes

Temperature 

increase 

• Wildfire

• Drought, erosion

• Vegetation changes

• Spread of invasive species

• Ice patch melt

• Altered freeze-thaw cycles

• Combustion, damage, destruction

• Exposed artifacts and cultural features

• Altered physical appearance, integrity

• Altered physical appearance, integrity

• Artifact decay and theft

• Saturation, desiccation, warping, biochemical changes

Altered 

precipitation 

• Earlier seasonal runoff, flooding

• Debris flows, slumping

• Down-cutting, mass wasting

• Increased moisture and humidity

• Extreme precipitation events

• Removal, damage, degradation

• Burial, removal, degradation

• Removal, damage, degradation

• Decay, oxidation, exfoliation, corrosion, biochemical 

changes

• Removal, damage, degradation, collapse, exposure

Figure 12.1—Prehistoric stone cairn 

exposed by wildfire in Custer 

National Forest. Intense wildfires, 

suppression, and rehabilitation 

activities annually affect hundreds 

of cultural resources in the Northern 

Rockies (photo: Halcyon LaPoint, 

Custer-Gallatin National Forest).

Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 465

and eastern Montana (fig. 12.3). These severe events are 

likely to accelerate hydrologic impacts to cultural resources 

(National Research Council 2002).

Perennial high-elevation snowfields contain ancient 

artifacts, the result of hunting and gathering excursions 

to mountain environments (Lee 2012) (fig. 12.4). Melting 

ice caused by a warmer climate poses a risk to previously 

ice-encased and well-preserved cultural resources. For 

example, melting ice patches in the Beartooth Mountains 

of south-central Montana have yielded ancient bone, wood, 

and fiber artifacts. Although melting ice patches provide 

research opportunities, the rapid rate of melting ice may 

preclude timely inspection by archaeologists, and newly 

exposed artifacts may decay or be stolen without adequate 

archaeological documentation.

Climate change also affects larger cultural landscapes 

whose integrity is derived from both cultural resources and 

environmental context (NPS 1994). Historic sites from 

the 1800s (e.g., Euro-American settlements, battlefields) 

are also valued historical resources, especially in some 

NPS units. Major shifts in dominant vegetation could 

potentially affect the physical and visual integrity of these 

landscapes (Melnick 2009). For example, whitebark pine 

(Pinus albicaulis) is an important historical component of 

the Alice Creek-Lewis and Clark Pass cultural landscape on 

the Continental Divide near Helena, Montana (fig. 12.5). 

Whitebark pine is currently in decline because warmer winter temperatures have accelerated the rate of mountain pine 

beetle (Dendroctonus ponderosae) outbreaks in addition to 

the effects of white pine blister rust (Cronartium ribicola), a 

nonnative fungal pathogen (Tomback and Kendall 2001; see 

also Chapter 8).

Cultural sites and landscapes are also recognized for 

their traditional importance to descendant communities, 

particularly American Indian tribes in the Intermountain 

West. Some traditional use areas provide foods, medicinal 

and sacred plants, pigments, and other resources, as well 

as ceremonial-religious places. Significant climate-induced 

effects in these landscapes, particularly altered distribution 

and abundance of vegetation, may curtail and even sever the 

continuous cultural connectivity and traditional use of these 

areas by indigenous peoples and local communities.

Figure 12.2—Prehistoric artifacts exposed in soil-deflated 

surface caused by drought conditions. Exposed artifacts 

are vulnerable to illegal collecting and livestock trampling 

(photo: Carl Davis, U.S. Forest Service).

Figure 12.3—Post-wildfire debris flow that obliterated or 

covered cultural resources in Meriwether Canyon, Helena 

National Forest. Early, intense spring runoff events may 

become more common in the future (photo: Carl Davis, 

U.S. Forest Service).

Figure 12.4—Melting perennial ice patches expose prehistoric 

artifacts in Custer-Gallatin National Forest. These highelevation locations document activities by Native American 

groups in the recent and distant past (photo: Craig Lee, 

Montana State University).

Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
466 USDA Forest Service RMRS-GTR-374. 2018

Climate change also poses risks to historic buildings and 

structures though increases in wildfire, flooding, debris flow, 

and extreme weather events (fig. 12.6). In addition to these 

direct threats, period furniture, interpretive media, and artifact collections inside historic (and nonhistoric) buildings 

may likewise be affected by those events. More nuanced 

stressors include increased heat, moisture, humidity, freezethaw events, insect infestation, and micro-organisms (mold), 

all of which accelerate weathering, deterioration, corrosion, 

and decay of buildings, structures, and ruins made of wood, 

stone, and other organic materials (UNESCO 2007).

Finally, climate change may diminish the appeal of 

cultural sites and landscapes for public visitation and 

interpretation. Extensive outbreaks of mountain pine beetle 

and other insects, which have been facilitated by higher 

temperature, have turned some historic landscapes in 

southwestern Montana from green to brown to gray (e.g., 

Logan and Powell 2001). In addition to visual impacts, 

dead and dying forests present hazards to hikers, sightseers, 

and other forest users (see Chapter 10). Over time, altered 

ecological conditions in cultural landscapes of the Northern 

Rockies region may reduce their attractiveness and value for 

tourism, recreation, and other purposes, thus affecting local 

communities and economies (see chapters 10, 11).

Risk Assessment

Climate change effects on cultural resources are likely to 

be highly variable across the Northern Rockies region by the 

end of the 21st century, depending on the particular stressor 

and geographic location. Wildfire is expected to create the 

highest risk for cultural resources and is expected to broadly, 

Figure 12.5—Whitebark pine 

mortality may affect the 

integrity and status of cultural 

sites, such as the Lewis and 

Clark Pass cultural landscape 

and National Register District 

shown here. Significant 

landscape change may also 

affect indigenous peoples 

and local communities who 

use the area and its resources 

(photo by Sara Scott, 

Montana Department of Fish, 

Wildlife and Parks).

Figure 12.6—Installing emergency roof supports 

in the main lodge, OTO Dude Ranch, CusterGallatin National Forest. Routine and emergency 

projects to stabilize, protect, and maintain 

historic buildings are likely to increase in a 

warmer climate (photo by Marcia Pablo, CusterGallatin National Forest).

Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 467

though unevenly, affect cultural resources on all national 

forests, national grasslands, and national parks, including 

locations that have already burned since the 1990s.

The prospect of prolonged aridity and drought caused 

by projected temperature increase may be partially offset 

if winter precipitation increases in the future (see Chapter 

3). Thus, it is difficult to quantify the long-term effects of 

drought, floods, and extreme weather events on cultural 

resources. In general, these natural processes, exacerbated 

by climate change, are likely to pose a significant risk to 

cultural resources. Resource loss will be greatest in those 

areas prone to major hydrologic events, such as at canyon 

mouths and in river bottoms where cultural sites are often 

concentrated. Cultural sites located here are difficult to armor and protect in the face of significant flooding and debris 

flows. Furthermore, artifact collectors may eventually target 

these areas because newly exposed cultural materials are 

often strewn over a wide area in the aftermath of a flood or 

debris flow; protection of these materials depends on active 

law enforcement.

Other potential climate change-related effects on cultural resources will be more subtle and moderate. Shifting 

distribution and abundance of vegetation are likely to affect 

the visual integrity of some cultural landscapes. Climate 

change effects to historic buildings or structures will be both 

gradual and cumulative (i.e., decay and degradation) and 

sudden and direct (i.e., structural collapse caused by moisture and snow loading). Certain natural resources associated 

with traditional cultural landscapes that tribal peoples continue to use today, may be diminished or entirely disappear. 

However, increased wildfire may increase the abundance 

of some culturally valuable species, such as huckleberry 

(Vaccinium spp.), common camas (Camassia quamash), and 

nodding onion (Allium cernuum).

Agency proposals and efforts to control, abate, or 

mitigate the projected effects of climate change may also 

affect cultural resources. For example, in anticipation of 

significant flooding events in the future, historic culverts 

and bridge abutments made of stone may be replaced with 

larger metal ones. Although project design and mitigation 

measures would reduce many adverse effects to cultural resources, landscape restoration projects designed to increase 

resilience to climate stressors could diminish the cultural 

resource base in some locations.

The effects of climate change on cultural resource tourism are difficult to estimate because this is contingent on 

social and economic factors. Visiting historic sites is popular 

throughout the Northern Rockies (Nickerson 2014), and 

tourism is an important economic contributor to many local 

communities (see Chapter 10). Hot, dry summer weather 

could reduce public interest in visiting cultural resources, 

cultural landscapes, and interpretive sites located on Federal 

lands, particularly in areas recently affected by severe wildfires or floods. This potential impact on forest tourism could, 

in turn, affect local communities to some extent.

Adapting to the Effects of 

Climate Change

Federal agencies in the Northern Rockies region have the 

capacity to address some of the projected effects of climate 

change on cultural resources. Fuels reduction around significant cultural resources is already in place in some locations 

to reduce the intensity and severity of future wildfires. 

USFS heritage personnel are engaged in all aspects of wildfire suppression and recovery, which facilitates protection of 

cultural resources threatened by wildfires. However, fire vulnerability assessment and abatement programs for cultural 

resources may need further emphasis to address a potential 

for more wildfires in the future.

Less progress has been made in completing vulnerability 

assessments or implementing protection strategies for 

cultural resources located in areas prone to large-scale hydrologic events, and the full scope of this risk is unknown in 

the Northern Rockies region. Hydrologic events are unpredictable, and protection measures such as stabilization and 

armoring are expensive. Viable protection measures often 

require hydrologic, engineering, and other resource expertise. Nonetheless, Federal agencies have a strong mandate to 

implement measures to protect cultural sites threatened by 

such natural processes and emergency events.

Survey and evaluation in areas where cultural resources 

are concentrated or likely are ongoing, although intermittent, in the Northern Rockies region. It will be possible to 

locate and monitor cultural resources potentially at risk only 

if these efforts are significantly expanded. High-elevation 

melting ice patches are a particular priority, but surveys are 

critical in other locations where cultural resources are likely 

to be affected by flooding and debris flows in mountain 

canyon and foothills areas. Correlating areas where cultural 

resources are common with areas where ice melt and flooding are expected will help to focus attention on landscapes 

at greatest risk.

Some climate-induced vegetation shifts in designated 

cultural landscapes could be partially mitigated through 

silvicultural treatments and prescribed burning, although the 

effectiveness of proposed treatments relative to the scope 

and scale of the cultural landscape is difficult to evaluate. 

Careful monitoring and tracking of vegetation stability and 

change in cultural landscapes will become increasingly 

important in future decades.

To date, the potential effects of climate change on the 

historic built environment in the Northern Rockies region 

has received relatively little attention. However, a variety of 

actions may eventually be necessary to abate or mitigate the 

projected effects of climate change on historic buildings and 

structures. Vulnerability assessments by qualified experts 

are necessary precursors to initiating any remediation work 

such as stabilization, armoring, and other interventions. In 

this context, historic preservation teams, volunteers, and 

partners will be important contributors to climate-related 

preservation work in the future.

Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
468 USDA Forest Service RMRS-GTR-374. 2018

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change 2007: The physical science basis. Contribution of 

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Intergovernmental Panel on Climate Change. Solomon, S.; 

Qin, D.; Manning, M. [et al.], eds. Cambridge, UK: Cambridge 

University Press. 996 p.

Lee, C.M. 2012. Withering snow and ice in the mid-latitudes: A 

new archaeological and paleobiological record for the Rocky 

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Logan, J.; Powell, J. 2001. Ghost forests, global warming, and 

the mountain pine beetle (Coleoptera : Scolytidae). American 

Entomologist. 47: 160–173.

Mayewski, P.A.; White, F. 2002. The ice chronicles: The quest to 

understand global climate change. Hanover, NH: University of 

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Quaternary Research. 52: 404–416.

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Age America. Berkeley, CA: University of California Press.

National Park Service [NPS]. 1994. Protecting cultural landscapes: 

Planning, treatment and management of historic landscapes. 

Preservation Brief 36. Washington, DC: U.S Department of the 

Interior, National Park Service.

National Park Service [NPS]. 2011a. Climate change at Big Hole 

National Battlefield. Upper Columbia Basin Network Resource 

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Clim_BIHO_ResBrief_20110114.pdf [Accessed December 12, 

2015].

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partnerships and science directorate. http://www.nps.gov/

history/tribes/aboutus.htm [Accessed November 30, 2015].

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Chapter 12: Effects of Climate Change on Cultural Resources in the Northern Rockies Region
USDA Forest Service RMRS-GTR-374. 2018 469

The Northern Rockies Adaptation Partnership (NRAP) 

provided significant contributions to assist climate change 

response in national forests and national parks of the 

Northern Rockies region. The effort synthesized the best 

available scientific information to assess climate change 

vulnerability, develop adaptation options, and catalyze 

a collaboration of land management agencies and stakeholders seeking to address climate change in the region. 

The vulnerability assessment and corresponding adaptation options provided information to support national 

forests and national parks in implementing respective 

agency climate change strategies described in the Forest 

Service, U.S. Department of Agriculture (USFS) National 

Roadmap for Responding to Climate Change (USDA 

FS 2010a) and Climate Change Performance Scorecard 

(USDA FS 2010b) (see Chapter 1), and the National Park 

Service (NPS) Climate Change Response Strategy (NPS 

2010). The NRAP process allowed all forests in the USFS 

Northern Region to respond with “yes” to scorecard 

questions in the organizational capacity, engagement, 

and adaptation dimensions. Further, the NRAP process 

enabled participating national parks to make progress toward implementing several components (communication, 

science, and adaptation goals) of the Climate Change 

Response Strategy (NPS 2010).

Relevance to Agency Climate 

Change Response Strategies

In this section, we summarize the relevance of the 

NRAP process to the climate change strategy of Federal 

agencies and the accomplishments of participating 

national forests, national grasslands, and national parks. 

Information presented in this report is also relevant for 

other land management agencies and stakeholders in the 

Northern Rockies region. This process can be replicated 

and implemented by any organization, and the adaptation 

options are applicable in the Northern Rockies region and 

beyond. Like previous adaptation efforts (e.g., Halofsky 

et al. 2011; Raymond et al. 2014), a science-management 

partnership was critical to the success of the NRAP. 

For others interested in emulating this approach, we 

encourage them to pursue this type of partnership as the 

foundation for increasing climate change awareness, assessing vulnerability, and developing adaptation plans.

Organizational Capacity, Education, and 

Communication

Organizational capacity to address climate change, as 

outlined in the Climate Change Performance Scorecard 

requires building institutional capacity in management 

units through training and education for USFS employees. Training and education were built into the NRAP 

process through workshops and webinars that provided 

information about the effects of climate change on water 

resources, fisheries, forest vegetation, nonforest vegetation, 

disturbance, wildlife, recreation, ecosystem services, and 

cultural resources. The workshops introduced climate tools 

and processes for assessing vulnerability and planning for 

adaptation.

The Climate Change Response Strategy challenges NPS 

staff to increase climate change knowledge among employees and to communicate this information to the public, in 

addition to the actions taken by the agency to respond to 

climate change. Although communication about climate 

change with the public was beyond the scope of the NRAP, 

knowledge generated through this process can be used for 

outreach and interpretive materials.

Partnerships and Engagement

The NRAP science-management partnership and process 

were as important as the products that were developed, 

because these partnerships are the cornerstone for successful 

agency responses to climate change. We built a partnership 

that included several Federal agencies as well as other 

organizations (e.g., EcoAdapt, Headwaters Economics) 

and universities (Oregon State University, University of 

Washington).

Elements 4 and 5 of the Climate Change Performance 

Scorecard require units to engage with scientists and scientific organizations to respond to climate change (element 4) 

and work with partners at various scales across all boundaries (element 5). Similarly, the Climate Change Response 

Strategy emphasizes the importance of collaboration and 

building relationships, in addition to products that support 

decisionmaking and a shared vision. The NRAP process 

therefore allowed both the USFS and the NPS to achieve 

unit-level compliance in their agency-specific climate 

responses.

The NRAP process encouraged collaboration between the 

USFS and NPS, supporting a foundation for a coordinated 

Chapter 13: Conclusions

S. Karen Dante-Wood and Linh Hoang
470 USDA Forest Service RMRS-GTR-374. 2018

regional response to climate change. By working with 

partners (Federal and nongovernmental), we increased our 

capability to respond to climate change. Responding to such 

a challenge requires using an all-lands approach, which this 

partnership fostered.

Assessing Vulnerability and Adaptation

Elements 6 and 7 of the Climate Change Performance 

Scorecard require units to assess the expected effects of 

climate change and determine which resources will be most 

vulnerable as a result, and identify management strategies to 

improve the adaptive capacity of the national forest lands. 

The NRAP vulnerability assessment used the best available 

science to identify sensitivity and vulnerability of multiple 

resources in the Northern Rockies region (table 13.1). 

Adaptation options for each of the resource areas were then 

developed and can be incorporated into resource-specific 

programs and plans.

The science-management dialogue identified management practices that are useful for increasing resilience and 

reducing stressors and threats. Although implementing all 

options developed in the NRAP process may not be feasible, 

resource managers can still draw from the menu of options 

Table 13.1—Risk assessment for resources in the vulnerability assessment for the Northern Rockies. The qualitative and quantitative 

approach for estimating magnitude and likelihood of climate change effects varies by resource and availability of information 

(see individual chapters for more detail).

Resource

Habitat, ecosystem function 

or species Magnitude of effects Likelihood of effects

Water resources Snowpack and glaciers High to low, depending on elevation 

and winter temperatures

High

Streamflow High to low across the region, 

depending on local climate

High to low across the region, 

depending on local climate

Fisheries Bull trout Moderate for 2040s, high by 2080s High for 2040s, moderate for 2080s

Westslope cutthroat trout and 

Yellowstone cutthroat trout

Low for 2040s, moderate for 2080s High for 2040s, moderate for 2080s

Vegetation – 

general types

Dry ponderosa pine and Douglasfir High High

Lodgepole pine and aspen mixed 

conifer

Moderate High

Mixed mesic white pine, western 

redcedar, western hemlock grand 

fir 

Moderate Low

Western larch mixed conifer High Very high

Whitebark pine/spruce-fir High High

Big sagebrush Highly variable Moderate 

Mountain big sagebrush and basin 

big sagebrush

Mountain big sagebrush – moderate; 

basin big sagebrush – high 

High

Threetip sagebrush and silver 

sagebrush

Moderate High

Western grasslands High High

Vegetation – 

tree species

Alpine larch High High

Cottonwood Moderate Moderate

Douglas-fir High High 

Engelmann spruce Moderate Moderate

Grand fir Moderate Moderate

Green ash Moderate High

Limber pine Low Low

Lodgepole pine Moderate High

Mountain hemlock High High

Ponderosa pine - var. ponderosa Moderate Moderate

Ponderosa pine – var. scopulorum Moderate Moderate

Quaking aspen Moderate High

Subalpine fir High High

Western hemlock Moderate Moderate

Western larch High Very high

Western redcedar Moderate Moderate

Western white pine Moderate Moderate

Whitebark pine Moderate Moderate

Chapter 13: Conclusions
USDA Forest Service RMRS-GTR-374. 2018 471

Vegetation – 

resource concerns

Carbon sequestration High Moderate

Landscape heterogeneity Moderate High

Timber production Moderate to high in northern Idaho High in north Idaho

Bark beetle disturbances Moderate Varies 

Invasive plant species High High

Wildfire regimes Low-moderate Moderate-high

Wildlife American beaver Moderate by 2100 Moderate by 2100

American pika Low in 2030, 2050; moderate by 

2100

Varies

Canada lynx Moderate by 2030, high by 2050, 

extreme by 2100

High

Fisher Low by 2030, moderate by 2050, 

probably high by 2100

High

Moose Moderate by 2100 Moderate by 2100

Northern bog lemming Moderate by 2050;

high by 2100

High by 2050

Pronghorn Moderate by 2100 Moderate by 2100

Pygmy rabbit Moderate by 2050; could be high 

by 2100

High by 2050

Townsend’s big-eared bat Moderate by 2100 Moderate by 2100

Ungulates (elk, mule deer, whitetailed deer)Uncertain, but probably low to 

moderate by 2100

Low to moderate in all time periods

Wolverine Low by 2030, moderate by 2050, 

high to very high by 2100

High in all time periods

Brewer’s sparrow Low to moderate by 2050; moderate 

to high by 2100

Moderate, depending on sagebrush 

habitat

Flammulated owl Largely unknown across all time 

periods

Largely unknown across all time 

periods

Greater sage-grouse Largely unknown across all time 

periods; depends on fire

Largely unknown across all time 

periods; depends on fire

Harlequin duck Moderate across all time periods Moderate across all time periods

Mountain quail Low to moderate across all time 

periods

Low to moderate across all time 

periods

Pygmy nuthatch Largely unknown across all time 

periods

Largely unknown across all time 

periods

Ruffed grouse Low to moderate across all time 

periods

Low to moderate across all time 

periods

Columbia spotted frog Moderate across all time periods, 

depending on fungal infections

Moderate across all time periods

Western toad Moderate across all time periods Moderate across all time periods

Recreation Warm-weather activities Moderate High

Snow-based recreation activities High High

Wildlife-based activities Hunting, wildlife viewing–low; 

fishing–moderate to high 

Hunting, wildlife viewing– moderate; 

fishing–high 

Gathering forest products Low Moderate

Water-based activities Low to moderate Moderate

Ecosystem services Building materials/wood products Large from non-climate forces Likely from non-climate forces

Cultural and heritage values Highly variable Highly variable

Erosion regulation Landslides and flooding have the 

potential for large sudden damages; 

costs of soil erosion are high.

High 

Fuel (firewood/biofuels) Firewood – low; biofuels – uncertain High

Mining, minerals Large from non-climate forces High

Viewsheds/clean air High High

Water quality High High

Water quantity Moderate High

Table 13.1—Continued.

Resource

Habitat, ecosystem function 

or species Magnitude of effects Likelihood of effects

Chapter 13: Conclusions
472 USDA Forest Service RMRS-GTR-374. 2018

as needed. Some adaptation strategies and tactics can be implemented on the ground now, whereas others may require 

changes in policies and practices or can be implemented 

when management plans are revised or as threats become 

more apparent.

The NRAP process used many of the principles and goals 

for assessing vulnerability and planning for adaptation that 

are identified in the Climate Change Response Strategy. 

The strategy calls for NPS units to implement adaptation in 

all levels of planning to promote ecosystem resilience and 

enhance restoration, conservation, and preservation of resources (NPS 2010). It specifically requires developing and 

implementing adaptation to increase the sustainability of 

facilities and infrastructure, and preserve cultural resources.

Science and Monitoring

Monitoring is addressed in element 8 of the Climate 

Change Performance Scorecard and in the Climate Change 

Response Strategy. Where applicable, the NRAP products 

identified information gaps or uncertainties in understanding 

climate change vulnerabilities of resources and management 

influences on vulnerabilities. These identified information 

gaps could drive the focus of monitoring and research 

intended to decrease uncertainties in management decisions. In addition, current monitoring programs that provide 

information for detecting climate change effects, and new 

indicators, species, and ecosystems that require additional 

monitoring, were identified for some resource chapters. 

Working across multiple jurisdictions and boundaries will 

allow NRAP participants to collaborate further in their 

research on climate change effects and effectiveness of 

implementing adaptation strategies and tactics.

Throughout the NRAP process, the best available science 

was used to understand projected changes in climate and effects on natural resources. This science can be incorporated 

into large landscape assessments such as forest/grassland 

planning assessments, environmental analysis for National 

Environmental Policy Act (NEPA) projects, or project design and mitigations.

Next Steps

The NRAP built on previous science-management 

partnerships by creating an inclusive forum for local and 

regional stakeholders to address issues related to climate 

change vulnerability and adaptation. Although this partnership was conducted at the regional scale, more work is 

needed to truly achieve an all-lands approach to adaptation. 

The Federal agencies involved have different missions 

and goals, and are at different stages in integrating climate 

change into resource management and planning. Although 

the differences allowed agencies to share approaches and 

experiences, it presented challenges in terms of creating a 

collaborative adaptation plan.

In the future, it may be valuable to develop partnerships 

around specific resource issues and implement adaptation 

options accordingly. Similarly, working at subregional 

scales would enable the assessment to target specific management concerns. Finally, engaging managers early through 

a query regarding priority information needs to support 

adaptation planning would help to generate “buy in” and 

ensure that products target important management needs.

The goal of this vulnerability assessment was to cover a 

range of natural resources that are critical to the Northern 

Rockies region. By exploring several resources in detail, 

participants identified species and ecosystems that are 

sensitive to climate change. More-detailed quantitative and 

spatially explicit vulnerability assessments would improve 

the scientific basis for detecting the effects of climate 

change and developing site-specific management responses 

and plans. Such assessments would also allow resource 

managers to prioritize locations for implementation. The 

process could also be expanded to include other systems and 

issues such as social and economic effects.

Implementing Adaptation Strategies 

and Tactics

Implementing adaptation strategies and tactics is the 

next, and most challenging, step. This will gradually occur 

with time, changes in policies, plan and program revisions, 

and major disturbances or extreme weather events. As 

previously noted, collaboration among landowners and management agencies will produce more-successful adaptation 

outcomes than operating independently.

Participants in the NRAP science-management partnership collaborated on two products: the vulnerability 

assessment and adaptation strategies and tactics. Before 

applying an adaptation strategy or tactic, land managers require a process to consider which actions are most 

important and identify the most important locations for 

implementing those actions. Landscape management strategies provide context for decisionmaking in which managers 

can be transparent in decisions about applying a strategy 

or tactic. Determinations of which adaptation options are 

most appropriate must consider the condition and context 

of the resource, social and ecological values, time scales for 

management, and feasible goals for treatment given changing climate (Peterson et al. 2011). Depending on the context 

and conditions, landscape management strategies can have 

various objectives, such as increasing resilience, resisting 

climate influences, facilitating transitions, or realigning/

restoring systems to be more resilient (Peterson et al. 2011).

Developing critical questions based on the vulnerability 

assessment, other factors important for resources, and 

site-specific ecological and social situations in the context 

of larger landscapes would assist land managers in making 

reasoned and transparent decisions in applying adaptation 

strategies and tactics. Workshops with large and small planning teams to develop resource-specific critical questions 

and their response to those questions could result in the 

Chapter 13: Conclusions
USDA Forest Service RMRS-GTR-374. 2018 473

development of broadly applicable management strategies 

(see fig. 13.1 for general framework and fig. 13.2 for example). A process similar to the Climate Project Screening 

Tool (Morelli et al. 2012) could be adapted to landscape 

management.

In many cases, similar adaptation options were identified 

for more than one resource sector, suggesting a need to 

integrate adaptation planning across multiple disciplines. 

Adaptation options that yield benefits to more than one resource are likely to have the greatest benefit (Halofsky et al. 

2011; Peterson et al. 2011; Raymond et al. 2014). However, 

some adaptation options involve tradeoffs and uncertainties 

that need further exploration. Assembling an interdisciplinary team to tackle this issue will be critical for assessing 

risks and developing risk management options.

Applications

The climate change vulnerability assessment and adaptation approach developed by the NRAP can be used by the 

USFS, NPS, and other organizations in many ways (fig. 

13.3, table 13.2). From the perspective of Federal land 

management, this information can be integrated into the following aspects of agency operations:

• Landscape management assessments/planning: The 

vulnerability assessment provides information on 

departure from desired conditions and best science 

on effects of climate change on resources for 

inclusion in planning assessments. The adaptation 

strategies and tactics provide desired forest/grassland 

conditions, objectives, standards, and guidelines for 

Figure 13.1—General 

framework for use of 

the Northern Rockies 

Adaptation Partnership 

vulnerability assessment 

and adaptation strategies 

and tactics to ask critical 

questions and develop a 

landscape management 

strategy.

Figure 13.2—Example 

of how a workshop 

can be conducted 

to answer critical 

questions and 

develop a landscape 

management strategy 

for cold-water fish.

Chapter 13: Conclusions
474 USDA Forest Service RMRS-GTR-374. 2018

land management plans and general management 

assessments.

• Resource management strategies: The vulnerability 

assessment and adaptation strategies and tactics 

can be used to incorporate NRAP best science into 

conservation strategies, fire management plans, 

infrastructure planning, and state wildlife action plans.

• Project NEPA analysis: The vulnerability assessment 

provides best available science for documenting 

resource conditions, analyzing effects, and developing 

alternatives. Adaptation strategies and tactics provide 

mitigation and design tactics at specific locations.

• Monitoring plans: The vulnerability assessment can 

help identify knowledge gaps that can be addressed 

by monitoring in broad-scale strategies, plan-level 

programs, and project-level data collection.

We are optimistic that climate change awareness, climate-smart management and planning, and implementation 

of adaptation in the Northern Rockies region will continue 

to evolve. We anticipate that within the next decade:

• Climate change will become an integral component of 

business operations.

• The effects of climate change on natural and human 

systems will be continually assessed.

• Monitoring activities will include indicators to 

detect the effects of climate change on species and 

ecosystems.

• Agency planning processes will provide opportunities 

to manage across boundaries.

• Restoration activities will be implemented in the 

context of the influence of a changing climate.

• Management of carbon will be included in adaptation 

planning.

• Institutional capacity to manage for climate change 

will increase within Federal agencies and local 

stakeholders.

• Managers will implement climate-informed practices 

in long-term planning and management.

Figure 13.3—Example applications 

of Northern Rockies Adaptation 

Partnership products to land 

management operations.

Table 13.2—Example of how information on climate change vulnerability and adaptation can be used in land management 

applications for dry forests. 

Vulnerability and adaptation information Land management application

Sensitivity to climatic variability and change

• Potential conversion to grassland 

• Many ponderosa pine forests have converted to Douglasfir types due to fire exclusion and are therefore more 

susceptible to future fires

• Forest/grassland planning: assessment phase

• Project National Environmental Policy Act (NEPA) 

analysis: existing condition and best science on effects of 

climate change on resource

Adaptation strategy

• Restore fire-adapted ponderosa pine stand conditions in 

order to facilitate transition

• Forest/grassland planning: desired conditions

• Project NEPA analysis: purpose and needs

Tactics

• Reduce competition from Douglas-fir and grand fir (thin, 

burn) in current mature pine stands

• Conduce frequent understory burning

• Retain current mature and older ponderosa pine stands

• Plant ponderosa pine where it has been lost

• Forest/grassland planning: objectives

• Project NEPA analysis: project design features and other 

mitigation

Chapter 13: Conclusions
USDA Forest Service RMRS-GTR-374. 2018 475

This assessment provides the foundation for implementing adaptation options that help reduce the negative effects 

of climate change and assist resources in the transition to a 

warmer climate. We hope that through building on existing 

partnerships, the assessment will foster collaborative climate 

change adaptation in resource management and planning 

throughout the Northern Rockies.

References

Halofsky, J.E.; Peterson, D.L.; O’Halloran, K.A.; [et al.]., eds. 

2011. Adapting to climate change at Olympic National Forest 

and Olympic National Park. Gen. Tech. Rep. PNW-GTR-844. 

Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 130 p.

Morelli, T.L.; Yeh, Y.; Smith, N.; [et al.]. 2012. Climate project 

screening tool: An aid for climate adaptation. Res. Pap. PSWRP-263. Albany, CA: U.S. Department of Agriculture, Forest 

Service, Pacific Southwest Research Station. 29 p.

National Park Service [NPS]. 2010. National Park Service climate 

change response strategy. Fort Collins, CO: U.S. Department of 

the Interior, National Park Service, Climate Change Response 

Program. 28 p. http://www.nps.gov/orgs/ccrp/upload/NPS_

CCRS.pdf [Accessed July 23, 2015].

Peterson, D.L.; Millar, C.I.; Joyce, L.A.; [et al.]. 2011. Responding 

to climate change in national forests: a guidebook for 

developing adaptation options. Gen. Tech. Rep. PNWGTR-855. Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station.

Raymond, C.L.; Peterson, D.L.; Rochefort, R.M., eds. 2014. 

Climate change vulnerability and adaptation in the North 

Cascades region. Gen. Tech. Rep. PNW-GTR-892. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station.

USDA Forest Service [USDA FS]. 2010a. National roadmap 

for responding to climate change. Washington, DC: U.S 

Department of Agricultue, Forest Service. http://www.fs.fed.us/

climatechange/pdf/roadmap.pdf [Accessed July 23, 2015].

USDA Forest Service [USDA FS]. 2010b. A performance 

scorecard for implementing the Forest Service climate change 

strategy. Washington, DC: U.S. Department of Agriculture, 

Forest Service. http://www.fs.fed.us/climatechange/pdf/

performance_scorecard_final.pdf [Accessed July 23, 2015].

Chapter 13: Conclusions

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