Photo by Kenny Regan 

Webinar	
  proceedings	
  and	
  summary:	
  

Ongoing	
  research	
  and	
  management	
  responses	
  	
  

to	
  the	
  mountain	
  pine	
  beetle	
  outbreak

October	
  2011	
  –	
  December	
  2012

United States 

Department 

of Agriculture 

Forest Service 

Rocky Mountain 

Research Station

Proceedings 

RMRS-P-70 

June 2014 

USDA	
  Forest	
  Service	
  

Rocky	
  Mountain	
  Research	
  Station,	
  

Rocky	
  Mountain	
  Region,	
  &	
  

Northern	
  Region	
  

Colorado	
  Forest	
  Restoration	
  Institute	
  

Warner	
  College	
  of	
  Natural	
  Resources,	
  

Colorado	
  State	
  University

Webinar	
  series	
  hosted	
  by:	
  

Technical	
  coordinators:	
  Megan	
  Matonis,	
  Rob	
  Hubbard,	
  	
  

Krista	
  Gebert,	
  Beth	
  Hahn,	
  Sue	
  Miller,	
  and	
  Claudia	
  Regan	
  
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Please specify the publication title and series number.

Publishing Services

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Mailing address Publications Distribution

Rocky Mountain Research Station

240 West Prospect Road

Fort Collins, CO 80526

Matonis, M., R. Hubbard, K. Gebert, B. Hahn, S. Miller, and C. Regan. 2014. Future 

Forests Webinar Series, Webinar Proceedings and Summary: Ongoing Research 

and Management Responses to the Mountain Pine Beetle Outbreak. Proceedings 

RMRS-P-70. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, 

CO. 80 pp.

Abstract

The Future Forest Webinar Series facilitated dialogue between scientists and 

managers about the challenges and opportunities created by the mountain pine 

beetle (MPB) epidemic. The series consisted of six webinar facilitated by the USFS 

Rocky Mountain Research Station, the Northern and Rocky Mountain Regions, 

and the Colorado Forest Restoration Institute. The series ran from October 2011 

to December 2012 and covered a variety of topics related to the MPB epidemic: 

potential fire risk and behavior, current and future vegetation conditions, wildlife 

habitats and populations, social and economic considerations, ecosystem- and 

watershed-level changes, and management responses. The purpose of these 

proceedings is to relate information shared during the webinar series (rather than 

to summarize all available research on implications of the MPB epidemic). These 

proceedings represent a snapshot of relevant scientific and management concerns 

related to this epidemic. In the coming decades, additional research and lessons 

learned by managers will continue to deepen and broaden our understanding of 

the future of post-epidemic forests.

Keywords: Mountain pine beetle, Lodgepole pine, Forest change, Socio-economic 

impacts, Wildlife habitat
Future Forest Webinar Series

October 2011-December 2012

Webinar proceedings and summary: 

Ongoing research and management responses 

to the mountain pine beetle outbreak

Technical coordinators: Megan Matonis, Rob Hubbard, 

Krista Gebert, Beth Hahn, Sue Miller, and Claudia Regan

Webinar series hosted by:

USDA Forest Service Colorado Forest Resoration Institute

Rocky Mountain Research Station, Warner College of Natural Resources,

Rocky Mountain Region, & Colorado State Univeristy

Northern Region

Contents

Chapter 1—Overview of the Future Forest Webinar Series.......................... 1

Background of the Future Forest Webinar Series Proceedings............................1

Goals of the Future Forest Webinar Series...........................................................1

Context of the MPB epidemic ..............................................................................2

Management challenges introduced by the MPB ................................................5

Outcomes of the webinar series ..........................................................................5

Literature cited..................................................................................................... 6

Chapter 2—Webinar summary: Important findings for managers................ 9

Introduction.......................................................................................................... 9

Resilient forests.................................................................................................... 9

Managing for fire hazards and risks....................................................................10

Current and future stand conditions..................................................................11

Sustainability of wildlife habitat.........................................................................12

Public safety ....................................................................................................... 13

Managing water resources.................................................................................14

Economic feasibility of management actions.....................................................15

Conclusions ........................................................................................................ 16

Literature cited................................................................................................... 17

Chapter 3—Post-epidemic fire risk and behavior....................................... 19

Introduction........................................................................................................ 19

Research findings ............................................................................................... 20

Literature cited................................................................................................... 26

Chapter 4—Forests in transition: Post-epidemic vegetation conditions...... 29

Introduction........................................................................................................ 29

Research findings ............................................................................................... 30

Literature cited................................................................................................... 35

Chapter 5—Ecological consequences of the MPB epidemic 

for habitats and populations of wildlife ................................................. 39

Introduction........................................................................................................ 39

Research findings ............................................................................................... 40

Literature cited................................................................................................... 45

Chapter 6—Beetles among us: Social and economic impacts of the 

MPB epidemic ....................................................................................... 49

Introduction........................................................................................................ 49

Research findings ............................................................................................... 50

Manager perspectives........................................................................................55

Literature cited................................................................................................... 58

Chapter 7—Small bugs with big impacts: Ecosystem and watershedlevel responses to the MPB epidemic .................................................... 61

Introduction........................................................................................................ 61

Research findings ............................................................................................... 62

Literature cited................................................................................................... 70

iii
Chapter 8—Moving forward: Responding to and mitigating effects 

of the MPB epidemic ............................................................................. 73

Introduction........................................................................................................ 73

Lessons learned.................................................................................................. 73

Literature cited................................................................................................... 79

Appendix A. Scientific names of insect, plant, animal, and fungi 

species .................................................................................................. 80

iv
USDA Forest Service RMRS-P-70. 2014. 1

Chapter 1—Overview of the Future Forest Webinar Series

Authors: Sarah Hines and Megan Matonis

Background of the Future Forest Webinar 

Series Proceedings

T

he Future Forest Webinar Series was created to facilitate dialogue between scientists and managers about the challenges and opportunities 

created by the mountain pine beetle1 (MPB) epidemic. A core team of scientists and managers from the USFS Rocky Mountain Research Station and the 

Northern and Rocky Mountain Regions worked together to develop the format 

and content of the series and written proceedings. The core team facilitated six 

webinars (from October 2011 to December 2012) covering the ecological and 

social dimensions of the MPB epidemic. Webinar recordings are available online 

through the Rocky Mountain Research Station (http://www.fs.fed.us/rmrs/

presentations/).

These written proceedings represent a synthesis of material presented during the webinar series. Many webinar participants indicated that written 

proceedings would add value to the series by providing a reference document 

and resource for informing future management decisions. Each chapter was 

authored by webinar presenters and members of the webinar core team, and 

the entire document was reviewed by independent experts from the Rocky 

Mountain Region of the Forest Service, Colorado Forest Restoration Institute, 

and University of Wyoming. The purpose of the proceedings is to relate information shared during the webinar series rather than to summarize all available 

research on implications of the MPB epidemic. These proceedings represent 

a snapshot of relevant scientific and management concerns related to this 

epidemic. In the coming decades, additional research and lessons learned by 

managers will continue to deepen and broaden our understanding of the future 

of post-epidemic forests.

Goals of the Future Forest Webinar Series

The concept for the Future Forest Webinar Series grew out of the work of the 

Rocky Mountain Research Station, Colorado Forest Restoration Institute, and 

other partners in 2009 and 2010. The goal was to assess the general information 

needs of managers regarding the MPB epidemic2 (Colorado Forest Restoration 

Institute 2010). At that point in time, the MPB epidemic was already well underway throughout the Intermountain West. Scientists and managers recognized 

that relatively little could be done to stem the beetles’ progression, but there 

was still a clear and pressing need to understand implications of this disturbance 

for post-epidemic forests. RMRS research scientists and others had been conducting research on the ecological and social consequences of the extensive tree 

1 See appendix A for scientific names of insect, plant, animal, and fungi species referenced in this document.

2 The term epidemic refers to the continental-scale MPB event, and the terms infestation or outbreak refer to local-scale events.
2 USDA Forest Service RMRS-P-70. 2014.

mortality, and managers were eager for preliminary findings and peer-reviewed 

results.

The Rocky Mountain Research Station convened a group of scientists and managers from the Northern and Rocky Mountain Regions of the Forest Service to 

develop a webinar series about the MPB epidemic. An overarching goal of the 

webinar series was to bring research scientists and resource managers together 

to exchange information about post-epidemic forests.

The series consisted of six webinars from October 2011 through December 2012 

(Table 1.1) with presentations by well-known managers and scientists from 

the USFS Rocky Mountain Region, Northern Region, Southwestern Region, and 

Rocky Mountain Research Station. Partners from Colorado State University and 

the University of Wyoming, who have first-hand experience in beetle-killed forests, were also included. The webinar series served as an avenue for informing 

managers of peer-reviewed research, and an opportunity for dialogue between 

scientists and managers about applications of the scientific information. It also 

allowed scientists to share research information with managers in the interim 

between data collection and publication, and created the opportunity for managers to influence future research questions and approaches.

Context of the MPB epidemic

The current MPB epidemic began in 1996, and as of 2012 had affected approximately 23 million acres of forestland across the western United States, severely 

impacting forests in Colorado, Wyoming, South Dakota, Montana, Idaho, and 

beyond (USDA Forest Service 2013). The MPB primarily attacks lodgepole pine, 

but also affects ponderosa, whitebark, Scots, and limber pine, and occasionally 

foxtail, bristlecone and pinyon pines. The MPB is native to the forests of western 

North America, and many smaller (endemic) outbreaks have occurred in the 

Table 1.1. The Future Forest Webinar Series consisted of six webinars spearheaded by a member of the webinar core team, a group 

of researchers and managers from the Rocky Mountain Research Station (RMRS) and Northern and Rocky Mountain Regions of 

the Forest Service tasked with designing the webinar series.

Webinar date Title Core team lead

October 18, 2011 Post-epidemic fire risk and behavior Kevin Ryan (RMRS, Fire, Fuel and Smoke 

Program Area)

January 10, 2012 Forests in transition: Post-epidemic 

vegetation conditions

Mike Battaglia (RMRS, Forest and 

Woodland Ecosystems Program Area)

March 6, 2012

Ecological consequences of the mountain 

pine beetle epidemic for wildlife 

habitats and populations

Vicki Saab (RMRS, Wildlife and Terrestrial 

Ecosystems Program Area)

August 28, 2012

Beetles among us: Social and economic 

impacts of the mountain pine beetle 

epidemic

Megan Matonis and Jan Engert (RMRS, 

Science Application & Integration)

October 30, 2012

Small bugs with large-scale impacts: 

Ecosystem and watershed-level 

responses to the mountain pine beetle 

epidemic

Rob Hubbard (RMRS, Air, Water and 

Aquatic Environments Program Area)

December 11, 2012

Moving forward: Responding to and 

mitigating effects of the mountain pine 

beetle epidemic

Claudia Regan (USFS Rocky Mountain 

Region) and Barry Bollenbacher (USFS 

Northern Region)
USDA Forest Service RMRS-P-70. 2014. 3

past. However, the scale of the current epidemic is historically unprecedented 

(Fig. 1.1). There is no clear consensus on exactly why the recent epidmic has 

grown to such an epidemic scale, but it is hypothesized that contributing factors include: (1) a severe drought in the mid-1990s to early 2000s that stressed 

forests, leading to increased vulnerability (Bentz and others 2010); (2) warmer 

temperatures, especially in November and April, that decreased beetle mortality and increased MPB populations (Bentz and others 2010); and (3) previous 

management practices, including a history of fire suppression, which led to large 

swaths of dense forests (Fettig and others 2007).

The MPB typically has a one-year developmental life cycle at lower elevations 

and a two-year life cycle at higher and colder elevations. However, milder winter 

temperatures at higher elevation attributed to a shortened one-year life cycle 

for beetles during the current epidemic. This phenomenon has led to faster 

population growth rates and contributed to the rapid expansion of the epidemic, 

especially between 2004 and 2008 (Chapter 5).

The primary mode of tree death is not directly through the burrowing activity 

of the MPB, but rather via the introduction of a blue-stain fungus that it carries 

(Chapter 7). The MPB burrows into the inner bark of trees, laying its eggs and 

carrying the fungal spores directly into the tree. The fungus then grows and 

blocks the xylem cells, eliminating the tree’s ability to transport water. A healthy 

tree may be able to resist a MPB attack by releasing large quantities of resin to 

push burrowing beetles out of the bark. A clear sign of a tree undergoing attack 

Figure 1.1. Counties reporting 

MPB activity from 2009 to 

2013 (USDA Forest Service, 

Forest Health Technology 

Enterprise Team). 
4 USDA Forest Service RMRS-P-70. 2014.

is the appearance of “pitch tubes,” or small popcorn-like areas of sap, on the 

trunk of a tree (Fig. 1.2).

If trees are drought-stressed and/or MPB populations are particularly large, 

a tree’s typical defense mechanisms may be insufficient to resist infestation. 

Within days of being infested, transpiration halts and affected trees begin to 

die (Chapter 4). Foliar moisture content immediately decreases, leading to 

increased needle flammability (Chapter 3), but the tree typically does not show 

visible signs of mortality (i.e., green needles turning red) until several months to 

Figure 1.2. Pine trees produce large quantities of resin and 

terpenes as their natural defense against MPBs. Trees can 

occasionally survive a MPB attack by pitching the bugs in 

their galleries or pushing them out entry holes in the bark 

(photo courtesy of the National Park Service).

Figure 1.3. Trees succumbing to MPB attack go through four stages that have different physical characteristics and 

implications for fire hazards, wildlife habitat, and human safety. (1) Dying trees with green needles are in the “green 

stage”; (2) dead trees with dry, red needles are in the “red stage”; (3) standing snags that have lost their needles are 

in the “gray stage”; and (4) snags that have fallen to the ground are in the “dead and downed stage” (adapted from 

Schoennagel and others 2012).
USDA Forest Service RMRS-P-70. 2014. 5

about a year later. Within several years after this “red phase,” the tree will drop 

all its needles and enter the needleless “gray phase.” These dead snags will fall 

to the ground over the course of years to decades (Fig. 1.3).

The epidemic has slowed in recent years. According to the Forest Health 

Protection unit of the USFS, the MPB epidemic only affected an additional 2.4 

million acres across the western U.S. in 2012. This is down from 3.8 million acres 

in 2011 and 8.8 million acres in 2009 (USDA Forest Service 2013). Decreased 

levels of infestation suggest that the MPBs are running out of new pine forests 

to infect.

Management challenges introduced by the MPB

Resource specialists and managers are struggling with challenges presented by 

the extensive tree mortality caused by the MBP. Conversations have turned to 

moving forward and managing for future forest conditions. Resource managers 

are especially concerned with:

• identifying issues of concern that may affect public safety or hamper agency 

response to safety concerns;

• developing management approaches that will develop a more resilient forest; 

and

• providing for the sustainability of wildlife and fish habitat.

Post-epidemic forests have different fuel loads and fire hazards than unaffected forests. This increases concern for the safety of firefighters, water supply 

facilities, interstate electricity transmission lines, and communities at the 

wildland-urban interface (WUI). Falling of beetle-killed trees presents a hazard 

to natural resource managers, recreation visitors, permittees, and contractors. 

Wildlife populations have also been affected by the MPB epidemic. Post-forest 

conditions have improved habitats for some species, such as woodpeckers, but 

reduced habitat suitability for others.

Managers are addressing these changes by reducing fuel loads and removing 

hazardous trees in some locations. They are also exploring methods to increase 

forest resilience. Managers and the public alike are aiming for adequate forests 

regeneration. The nature of management responses is influenced by timing of 

disturbance events, risk management objectives, organizational inertia, and 

pre-existing management goals across the landscape. A suite of management 

options are possible in areas where managers anticipated MPB-related issues 

(Fettig and others 2014). Research can help managers understand social and 

ecological consequences of the MPB epidemic and inform management activities in post-epidemic forests.

Outcomes of the webinar series

The webinar series was widely attended and well received by managers and researchers alike. Participation ranged from 70 to over 180 people, with the entire 

series reaching about 500. Roughly half of the webinar attendees were affiliated 
6 USDA Forest Service RMRS-P-70. 2014.

with the Forest Service, and about a quarter worked for other federal, state, and 

local agencies. The remaining participants represented 15 different universities, 

25 private companies, and 14 non-government organizations (Fig. 1.4).

The core team solicited feedback from webinar attendees by distributing a survey at the end of the series. About 40 participants submitted responses, most of 

which were positive about the format and outcomes of the series. About 90 percent of respondents agreed or strongly agreed that the Future Forest Webinar 

Series was a useful forum for discussing research findings and management 

implications. In addition, over three-fourths of respondents agreed or strongly 

agreed that information from the series has better prepared them for future 

management decisions regarding the MPB epidemic. Respondents were generally satisfied with the level of detail provided by researchers and the amount of 

time allocated to questions and discussions.

Over half of the respondents thought that the series should have included more 

“take home” messages from researchers and on-the-ground observation from 

managers. To address this, Chapter 2 summarizes the entire webinar with an 

emphasis on management, and the chapters that follow pair research findings 

with management implications wherever possible.

Literature cited

Bentz, B.J., R. Jacques, C.J. Fettig, E.M. Hansen, J.L. Hayes, J.A. Hicke, R.G. Kelsey, 

R.G., J.F. Negrón, and S.J. Seybold. 2010. Climate change and bark beetles of 

the Western United States and Canada: Direct and indirect effects. BioScience 

60:602-613.

Figure 1.4. The Future Forest Webinar Series 

was attended by 500 different individuals 

representing a variety of governmental 

agencies, universities, non-governmental 

organizations, and private companies.

U.S.	
  Forest	
  

Service;	
  56%	
  

Other	
  federal	
  

agencies;	
  9%	
  

State	
  /	
  local	
  

agencies;	
  14%	
  

Canadian	
  

agencies;	
  4%	
  

Universi?es;	
  6%	
  

Private	
  

companies;	
  6%	
  

NGOs;	
  5%	
  
USDA Forest Service RMRS-P-70. 2014. 7

Colorado Forest Restoration Institute. 2010. Beyond the bugs: The future range 

of variability of communities and forest landscapes. Conference report, 19-

21 April 2010, Steamboat Springs, CO. Colorado State University, Colorado 

Forest Restoration Institute, Fort Collins, CO. 14 pp. [online] URL: http://

coloradoforestrestoration.org/CFRIpdfs/2010_BeyondBugsConferenceReport.

pdf.

Fettig, C.J., K.D. Klepzig, R.F. Billings, A.S. Munson, T.E. Nebeker, J.F. Negrón, and 

J.T. Nowak. 2007. The effectiveness of vegetation management practices for 

prevention and control of bark beetle infestations in coniferous forests of 

the western and southern United States. Forest Ecology and Management 

238:24-53.

Fettig, C.J., K.E. Gibson, A.S. Munson, and J.F. Negrón. 2014. Cultural practices 

for prevention and mitigation of mountain pine beetle infestations. Forest 

Science 60. [online] URL: http://dx.doi.org/10.5849/forsci.13–032.

Schoennagel, T., T.T. Veblen, J.F. Negron, and J.M. Smith. 2012. Effects of 

mountain pine beetle on fuels and expected fire behavior in lodgepole pine 

forests, Colorado, USA. PLoS ONE 7(1): e30002. [online] URL: http://www.

plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030002.

USDA Forest Service. 2012. Major forest insect and disease conditions in the 

United States: 2011. FS-1000. U.S. Department of Agriculture, Forest Service, 

Forest Health Protection, Washington, DC. 40 pp.

USDA Forest Service. 2013. Bark beetles: Summary for 2000-2012, Western U.S. 

U.S. Department of Agriculture, Forest Service, Washington, DC. 3 pp. [online] 

URL: http://www.fs.fed.us/foresthealth/technology/pdfs/MpbWestbb_

FactSheet.pdf.

Meet the chapter authors

Sarah Hines is a Science Delivery Specialist with the 

Rocky Mountain Research Station of the Forest Service. She 

joined the agency as a Presidential Management Fellow 

after graduating from the University of Michigan with a 

master’s in natural resources. Sarah provides assistance to 

the Climate Change Resource Center and helps make forest 

science more accessible to land managers. She created 

the ‘Science You Can Use’ Bulletin, a publication sent to 

almost 2,500 managers across the Intermountain West 

summarizing research findings and their management 

implications. Reach Sarah at shines@fs.fed.us; 970-498-

1135.

Megan Matonis is a Graduate Student Cooperator with 

the Rocky Mountain Research Station and a PhD student at 

Colorado State University. Her dissertation research focuses 

on the development and use of locally-relevant ecological 

information to empower collaborative forest restoration. 

Megan worked for the Forest Service Policy Analysis staff in 

Washington, DC after receiving a master’s in forestry from 

Michigan State University. Megan can be reached at megan.

matonis@colostate.edu; 970-498-1342.
8 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 9

Chapter 2—Webinar summary: Important findings for 

managers

Author: Claudia Regan

Introduction

T

his chapter summarizes key findings and offers take-home messages of 

the Future Forest Webinar Series with regard to resource management 

planning, analyses, and project design. In the wake of the mountain pine 

beetle (MPB) epidemic, resource managers are especially concerned with developing more resilient forests, providing for the sustainability of wildlife and fish 

habitat, public safety, and managing our water resources. We attempted to provide information to support these management goals via the series of webinars. 

More details on the findings of each webinar are presented in the subsequent 

chapters of these proceedings.

Resilient forests

Resource managers are interested in developing management approaches that 

contribute to resilient forests in the future.3 They want to ensure that forests 

regenerate after a disturbance and maintain their structure and function over 

the long term. They are also concerned about invasive species and soil erosion that may be exacerbated by beetle-caused tree mortality and subsequent 

disturbances, including 

post-epidemic salvage 

operations.

Managing for resilience 

requires knowledge 

about potential 

changes in forest conditions with and 

without management 

treatments. Subalpine 

forests evolved with 

widespread and severe 

disturbances, and the 

species dominating 

these ecosystems 

are adapted to these 

conditions (Fig. 2.1). 

The composition and 

structure of subalpine 

forests vary across the 

3 Resilience is the ability of an ecosystem to recover from disturbance (natural or anthropogenic) without shifting to an alternative state 

(i.e., substantially different structure, composition, and function) (SER 2004). 

Figure 2.1. Subalpine forests have recovered from disturbances in the past, including massive MPB 

epidemics, wildfires, and windfall events (photo by J.M. Miller in 1924 of the Tenaya Ghost Forest in 

Yosemite National Park showing lodegpole pine regeneration a decade after the MPB and lodgepole 

needle miner killed overstory trees; Furniss 2007).
10 USDA Forest Service RMRS-P-70. 2014.

West. How does this variability contribute to their resilience in the wake of the 

epidemic? The recent MPB epidemic is unprecedented in terms of its extent, 

geographic distribution, and longevity, but managers want to know if recovering 

subalpine forests are on a different trajectory than they might following more 

characteristic disturbances.

Managing for fire hazards and risks

Resource managers are concerned about the possibility of increased wildfire 

hazards, especially in the WUI, following the MPB epidemic. They recognize that 

the widespread death of trees dramatically changes fuel conditions over time, 

but they are uncertain about potential impacts on fire hazard and behavior. There 

is an interest in ameliorating short-term effects through fuel treatments and 

in planning for treatments that might have positive resource outcomes in the 

future. The webinar Post-epidemic fire risk and behavior focused on the fire behavior research of Forest Service researchers and their collaborators (Chapter 3), 

and additional research on MPB and fire interactions were presented during the 

webinar Forests in transition: Vegetation structure and composition (Chapter 4).

This research suggests that fire behavior in beetle-killed forests may be more 

complex than initially expected. Larger safety zones may be required for fire 

operations during the red stage of the MPB attack due to greater heat release 

(Fig. 2.2). This may also be true for fire operations in cut areas due to greater 

surface fuel loads and in uncut stands following massive windthrow events. 

Firefighters might decline assignments on wildland fires burning in beetle-killed 

stands given the high hazards involved.

Information on fuel loads and fire behavior in the gray stage is more limited. 

Predicting fire behaviors under gray stage or future conditions remains an area 

of uncertainty with conflicting findings. Public safety concerns may call for 

conservative approaches that would favor management to mitigate future fire 

concerns.

• The potential for crown fire and fire intensity (heat release) increases as the 

proportion of red-stage trees in a forest increases. 

• Stand structure and the nature of MPB outbreaks in space and time (i.e., low 

and slow mortality pulses vs. high and fast mortality pulses) affect how MPB 

outbreaks influence the risk of crown fires. 

• Tree removal in post-epidemic forests can result in a three-fold increase in 

surface fuels for several years after treatment. Higher fuel loads can result in 

greater flame lengths, potentially decreasing our ability to suppress fires with 

ground tactics.

• However, uncut stands could have higher fuels loads in the long-term as dead 

trees fall to the ground.

Management 

Implications
USDA Forest Service RMRS-P-70. 2014. 11

Current and future stand conditions

The webinar Forests in transition: Vegetation structure and composition covered research that is addressing uncertainties about how 

changing fuel profiles after the MPB epidemic might influence future 

fire behavior and/or impair fire suppression efforts (Chapter 4). 

We learned that forested landscapes in the future may have different structures and compositions than before the MPB epidemic. 

Management decisions regarding the removal of beetle-killed trees 

will influence the types of forests that develop.

We also learned that forests are responding positively to the 

increased availability of resources (light, nutrients, etc.) with 

rapid growth of residual trees and new tree recruitment (Fig. 2.3). 

Simulations of stand development using the Forest Vegetation 

Simulator suggested that increased growth of residual trees, as well 

as new recruitment, might return stands to pre-outbreak basal areas 

Figure 2.2. Fire behavior in beetle-killed 

forests is complex and difficult to 

predict. Research shows that forests 

with many red-stage trees have a 

greater potential for crown fires. Fires 

in red-stage forests also burn with a 

higher intensity (greater heat release) 

than fires in green forests (photo 

from 2009 Kelly Creek Fire in British 

Columbia, photo courtesy of B.C. 

Wildfire Management Branch).

Figure 2.3. Advanced regeneration and new 

recruitment of tree species are abundant in 

most post-epidemic stands (photo by Chuck 

Rhoades, USDA Forest Service).
12 USDA Forest Service RMRS-P-70. 2014.

within a century. The simulations reveal that lodgepole pine may continue to 

dominate harvested stands over the next century, while some uncut stands may 

have larger proportions of subalpine fir.

Sustainability of wildlife habitat

Resource managers need information on the consequences of the MPB 

epidemic for wildlife habitat and wildlife populations. This information 

will support conservation and recovery efforts and help in prioritizing 

treatment sites. A team of researchers and resource specialists addressed some of these information needs in the webinar Ecological 

consequences of beetle outbreaks for habitats and populations of wildlife

(Chapter 5).

A wildlife biologist with the Rocky Mountain Research Station illustrated 

how life history traits provide clues about the impact of disturbances 

on different bird species. Cavity-nesting birds, beetle foragers, and bark 

insectivores (e.g., hairy woodpeckers and American three-toed woodpeckers) often respond positively to MPB outbreaks and fire (Fig. 2.4). 

This is due to increased availability of snags for nesting and food 

resources. In contrast, foliage gleaners and canopy-nesting birds (e.g., 

golden-crowned kinglet) are likely to respond negatively because they 

prefer dense forest canopies.

Impacts of the MPB epidemic on wildlife habitat will change over time as 

the forests regrow and snags fall down. Wood-boring insects that colonize MPB-killed trees can serve as a foraging resource for woodpeckers 

even 4-5 years following a MPB attack.

• Post-epidemic forests are undergoing extensive regeneration. Tree planting is 

largely unnecessary to ensure forested conditions in the future.

• Recovery of post-epidemic forests will depend on species composition of 

surviving trees and advanced regeneration.

Д The abundance of subalpine fir and Engelmann spruce will increase in some 

stands, especially if the abundance of lodgepole pine declined substantially 

during the beetle epidemic. 

Д Lodgepole pine will continue to dominant some stands, especially those 

where pre-epidemic densities of subalpine fir and Engelmann spruce were 

low.

Д Aspen abundance is increasing in stands without substantial competition 

from subalpine fir.

• Harvesting beetle-killed trees can promote the recruitment of lodgepole pine or 

aspen, while subalpine fir recruitment more likely in uncut stands.

Management 

Implications

Figure 2.4. Several woodpecker species, 

including the black-backed woodpecker, 

forage for MPBs and other bugs under 

the bark of dead snags (photo courtesy 

of USDA Forest Service).
USDA Forest Service RMRS-P-70. 2014. 13

Webinar presenters also discussed the use of models to evaluate changes in 

wildlife habitat over time. They found that models are useful tools for predicting 

habitat suitability under different climate conditions and disturbance regimes. 

Some models can examine interactions among disturbances (e.g., climate 

change, wildfires, and MPB outbreaks). Researchers suggested several best practices for using models:

• Determine the appropriate spatial and temporal scale for projections. 

Projections at landscape scales are necessary for species that have large 

home ranges or migrate from season to season. If snags are important habitat 

for the focal species, annual or decadal projections at the stand scale are 

more appropriate.

• Try linking site-specific research projects with broader monitoring programs to 

develop multi-scale inferences about habitat suitability.

• The future is not set in stone, so models can help assess the impact of 

different management decisions under a range of potential conditions (e.g.,

climate scenarios).

• Understand the assumptions and limitations of models. For example, some 

datasets are less reliable than others, and this can greatly influence the 

reasonableness of model predictions.

• Qualitative modeling approaches, such as scenario planning, are often helpful 

when future conditions are dynamic and largely unknown and/or when 

quantitative data is not available.

Public safety

Resource managers continue to be concerned about the direct consequences of 

forest insect epidemics to human safety. They are interested in understanding 

issues that relate to agency responses to safety concerns. Once the extent and 

severity of the MPB epidemic became apparent, managers worked to address 

• Animal species respond differently to disturbances like the MPB epidemic based 

on their life history traits.

Д Species that utilize snags for feeding and/or nesting (e.g., woodpecker species) 

often benefit from MPB outbreaks and fires. Habitat suitability for these 

species can decline over time as snags fall down.

Д Species preferring dense forest overstories (e.g., foliage-gleaning and canopynesting birds) often decline following a MPB outbreak, but populations might 

rebound as forest stands recover.

• Retention of snags for wildlife habitat is an important project consideration for 

some large-scale salvage operations. Managers should also remember that snag 

fall rates are highly variable.

Д Research shows that woodpeckers preferentially forage on large-diameter 

snags.

Д Anywhere from 70-90 percent of snags fall within 5 years of a MPB outbreak. 

Higher fall rates are generally associated with warmer and wetter conditions.

Management 

Implications
14 USDA Forest Service RMRS-P-70. 2014.

current and future safety of employees, recreation visitors, permittees, and 

contractors who use the National Forests. In addition, the agency has an interest in addressing the safety of communities in the wildland urban interface 

(WUI). Dead and dying trees eventually fall, creating imminent and future risks 

to people and structures (Fig. 2.5). Resulting changes in fuel profiles are seen as 

potentially influencing fire potential and behavior and impacting suppression 

responses (Chapter 3, discussed earlier).

Figure 2.5. Trees killed by MPB attacks 

eventually weaken and fall, posing a serious 

safety concern for forest users (photo 

courtesy of USDA Forest Service).

• Respondents generally support the management of forest conditions to 

decrease the effects of wildfire that may potentially be influenced by changes in 

fuel profiles associated with dying, dead, and falling trees. 

• Respondents are generally willing to accept the risks of recreating in beetlekilled forests, and they accept that certain activities are restricted or no longer 

possible.

• There is less agreement among respondents that managers are doing everything 

they can to respond to tree mortality from MPBs.

Management 

Implications

Knowing the perceptions, beliefs, and preferences of the public can help land 

managers identify the issues, communicate better with the public, and improve 

collaborative efforts. The webinar Beetles among us: Social and economic impacts of the mountain pine beetle epidemic drew largely on a survey of public 

perceptions by researchers at Colorado State University (Chapter 6).

Managing water resources

The webinar Ecosystem and watershed level responses to the mountain pine 

beetle epidemic summarized research by forest ecologists and hydrologists at 

the Rocky Mountain Research Station (Chapter 7). Research shows that water 

yield and quality has not changed in the first years following the MPB epidemic. 

Stream nitrogen levels remain below those expected to cause problems for human health. Uptake by residual vegetation and new recruits has dampened the 

loss of nutrients to surface water.

Managers should be aware of how treatments in post-epidemic forests can 

alter water yields and soil resources. Treatment of slash can have particularly 
USDA Forest Service RMRS-P-70. 2014. 15

pronounced effects on snow retention and soil nutrients in forest ecosystems 

(Fig. 2.6). Additional research is needed to understand impacts of post-epidemic 

management to riparian ecosystems, but preliminary findings suggest these ecosystems are especially sensitive to mechanical disturbances and pile burning.

Economic feasibility of management actions

The amount of mitigation and hazard removal that managers can undertake 

in post-epidemic forests is limited by funding and the availability of forestindustry infrastructure. States with robust forest-products infrastructure, such 

as Montana, can finance at least some of their management costs by selling 

some or all of the material. In places where such infrastructure is sparser, like in 

Colorado, the material is often piled and burned in the woods, offsetting none of 

the costs of treatment. Utilizing woody material for bioenergy, rather than piling 

and burning it in the forest, also offsets carbon emissions.

• Snow retention and associated spring runoff are impacted by post-epidemic 

management decisions.

Д Removal of trees in large groups can decrease snow retention due to wind 

scour. 

Д Retaining slash in post-epidemic forests increases surface roughness and will 

help to keep snow on the ground.

• Different methods of treating slash in post-epidemic forests can impact future 

stand development.

Д Slash retention (i.e., lop and scatter) has positive effects on soil resources and 

seedling recruitment and growth relative to other options.

Д Burning the very large and numerous slash piles resulting from post-epidemic 

management can have long-lasting negative impacts (i.e., overs 50 years) on 

soil nutrients and seedling recruitment. 

• Riparian ecosystems are particularly sensitive to management approaches that 

emphasize hazard tree removal and pile burning. 

Management 

Implications

Figure 2.6. Slash management techniques 

can impact snow retention, soil nutrient 

availability, and seedling development. 

Lop and scatter approaches increase 

snow retention, often leading to greater 

soil moisture and enhanced seedling 

recruitment and growth (photo by Byron 

Collins, USDA Forest Service).
16 USDA Forest Service RMRS-P-70. 2014.

There are significant challenges to developing the capacity of private industries 

to utilize woody biomass. These include:

• Uncertainty in the amount of timber available to investors in the coming 

decades.

• High transportation costs to haul timber or biomass from infested forests to 

far-away mills.

• The price that the woody material receives on the market, as well as the price 

of alternatives. For example, the lower the cost of natural gas, the lower the 

price purchasers are willing to pay for biomass.

Conclusions

The MPB epidemic has greatly altered the future of forests across the West. 

The conditions across post-epidemic landscapes are complex and the future is 

largely uncertain. Implications of the epidemic for public safety, fire hazards, 

forest vegetation, and wildlife populations are variable across the landscape and 

will change over time. Management decisions have the potential to steer forests 

away from an undesirable future, but guidance is needed on how this might be 

accomplished (Fettig and others 2014).

Navigating through this complex and dynamic situation calls for continual 

interaction among managers, resource specialists, and scientists (Fig. 2.7). The 

process of developing, delivering, and implementing scientific information is 

most effective when it incorporates diverse perspectives, training, and expertise. For example, entomologists understand environmental controls of MPB 

outbreaks, forest ecologists have insights about forest development over time, 

and wildlife biologists know which variables are important for habitat suitability. 

Discussions among scientists and managers can also ensure that research is 

relevant and focused on the right questions.

Figure 2.7. A fully collaborative science cycle involves 

continual interactions among researchers, 

managers, and other science users. Interactions can 

familiarize non-scientists with research methods, 

make researchers aware of information needs, and 

improve the usability of research results (USDA 

Forest Service 2009).
USDA Forest Service RMRS-P-70. 2014. 17

The Future Forest Webinar Series helped to kick-start these interactions. Our 

hope is that the webinar coordinators, presenters, and participants continue 

working together; there is still much to learn about the future of post-epidemic 

forests.

Literature cited

Fettig, C.J., K.E. Gibson, A.S. Munson, and J.F. Negrón. 2014. Cultural practices 

for prevention and mitigation of mountain pine beetle infestations. Forest 

Science 60. [online] URL: http://dx.doi.org/10.5849/forsci.13-032.

Furniss, M.M. 2007. Forest entomology in Yosemite National Park: Glimpses 

of forest renewal 1903-1984, and the creation of the Tenaya Ghost Forest. 

American Entomologist 53(4):202-207.

SER. 2004. The SER international primer on ecological restoration. Society 

for Ecological Restoration International, Science & Policy Working 

Group, Washington, DC. [online] URL: https://www.ser.org/resources/

resources-detail-view/ser-international-primer-on-ecological-restoration.

USDA Forest Service. 2009. Assessment of technology transfer within the USDA 

Forest Service: Final report. USDA Forest Service, State & Private Forestry and 

Research & Development, Washington, DC. Unpublished report. 25 pp.

Meet the chapter author

Claudia Regan is the Regional Ecologist with the Rocky 

Mountain Region of the Forest Service. She has worked 

with the agency as a full-time employee for 18 years and 

in temporary or seasonal capacities for 6 years. Regional 

Ecologists serve as applied scientists who bridge scientific 

research with resource management issues and work 

toward information synthesis, delivery, and application. 

Claudia has Bachelor’s and Master’s degrees in Forest 

Science from Southern Illinois University and a Ph.D. in 

Ecology from Colorado State University. Reach Claudia at 

cregan@fs.fed.us; 303-275-5004.
18 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 19

Fuel

Microclimate

Structure

Chemistry

Moisture content

Structural and 

non-structural 

compounds

Arrangement 

(horizontal or 

vertical)

Distribution 

(surface or aerial)

Changes dependent 

on time since attack

Chapter 3—Post-epidemic fire risk and behavior

Authors: Russ Parsons, Matt Jolly, Paul Langowski, Megan Matonis, and Sue Miller

Presenters: Russ Parsons, Matt Jolly, and Paul Langowski

Introduction

Citizens, government officials, and natural resource managers are greatly 

concerned about potential impacts of the mountain pine beetle (MPB) 

epidemic on fire hazards and risk. Some mountain towns are surrounded 

by dead and dying trees. In the Rocky Mountain Region of the Forest Service, 

the MPB epidemic threatens over 250,000 acres of the wildland-urban interface 

(WUI; USDA Forest Service 2011). This post-epidemic landscape also poses 

hazards for firefighter safety due to heavy fuel loads and unpredictable fire 

behavior. Abundant snags are especially dangerous for firefighters working in 

beetle-killed forests.

Changes in fuel and microclimate conditions caused by the MPB epidemic 

(Fig. 3.1) add another dimension of complexity to wildfire concerns across the 

West. Many forested landscapes have not burned in nearly a century, leading to 

an abundance of trees and accumulation of fuels, setting the stage for large and 

severe wildfires. The death of trees due to the MPB has exacerbated this situation and created a need for extensive fuel reductions in many areas. Hotter and/

or drier climates in the future might further worsen the situation. Lodegepole 

pine forests evolved with an infrequent and severe fire regime, but many people 

find this type of fire behavior unacceptable, especially in the WUI.

Researchers and managers are working together to understand the interaction 

between MPB outbreaks and wildfires and to develop the appropriate responses. 

Figure 3.1. The MPB epidemic has 

altered fuel and microclimate 

conditions in forest stands. Fuel 

loads and microclimates will change 

over time due to management 

decisions and forest regrowth. These 

changes can result in unexpected 

fire behavior, with serious 

implications for fire operations 

(diagram by Matt Jolly, USDA Forest 

Service).
20 USDA Forest Service RMRS-P-70. 2014.

Many potential impacts of the MPB epidemic on fire hazards and behavior are 

still a matter of debate, and some questions remain unanswered. Some researchers suggested that post-beetle landscapes have a lower potential for crown fires, 

while others suggested risk of crown fires may increase in these forests. Others 

found that generalizations could not be made, since fuel loads and microclimates 

differ substantially between beetle-killed stands and will change considerably 

over time. Adding to the difficulty in understanding the situation is the fact that 

many fire behavior models used to analyze potential effects of the MPB epidemic 

on fuel loads were not designed for exploring such interactions.

Research findings

Research finding #1: Current operational models are greatly limited in 

their ability to accurately predict fire risk and behavior in post-epidemic 

forests.

Assumptions of fuel homogeneity and other simplifications within operational 

fire behavior models used in the United States make it difficult to realistically 

represent impacts of MPB outbreaks on fuels and fire behavior. This significantly 

limits their application in modeling fire behavior for stands with beetle-killed 

trees (Jolly and others 2012b; Jenkins and others 2014). MPB outbreaks typically result in stands with complex arrangements of trees in all different stages 

of mortality. Operational fire behavior models cannot currently account for 

this type of variability in fuel structures. In addition, they cannot incorporate 

changes in wind dynamics as trees transition between stages (e.g., from gray to 

down). Unrealistic predictions from these models have contributed to confusion among researchers, managers, and the public (Hoffman and others 2012, 

Jenkins and others 2014).

Physics-based models, such as FIRETEC and the Wildland-Urban Interface Fire 

Dynamics Simulator (WFDS), show great promise for overcoming inadequacies presented by operational fire behavior models (Hoffman and others 2013). 

These models can represent mixes of green and red trees typical of beetleattacked stands because they represent the forest as a collection of individual 

trees, rather than as a homogeneous block. They also capture critical interactions between fuel, fire, and the atmosphere (Fig. 3.2).

At this time, physics-based models are used primarily in research, but work 

is underway to make them operationally useful for fire and fuel managers. A 

limitation of physics-based models is their data-intensive nature. Use of these 

models requires knowledge about the location of individual trees and detailed 

measurements of surface and canopy fuels.

• Predictions from standard fire behavior models (e.g., BEHAVE, FlamMap, and 

NEXUS) are highly unreliable for stands affected by the MPB epidemic. 

• Consider using short-term fixes to improve predictions of current operational 

models, such as reducing crown base height in Van Wagner crown fire model to 

compensate for lower foliar moisture contents.

Management 

Implications
USDA Forest Service RMRS-P-70. 2014. 21

Research finding #2: Fire hazards are greater and fire behavior more 

severe when trees are in the red stage of a beetle attack.4

The flammability of pine branches and needles increases between the green and 

red stages of a beetle attack. In a replicated laboratory study, scientists with the 

Rocky Mountain Research Station determined that the greater flammability of 

red needles is due to their lower foliar moisture and altered chemistry. Ignition 

rates are about three times faster for red needles than healthy green needles 

(13 vs. 35 seconds) (Jolly and others 2012a). When considered at the scale of 

whole trees, such changes in flammability can be significant. Forest Service 

researchers compared fire behavior between a green healthy tree and a red 

stage tree using a physics-based fire model, WFDS. They found that heat was 

released twice as fast from the combustion of red needles as from green needles 

(Fig. 3.3). These differences are partially explained by changes in the chemical 

composition of needles after a beetle attack. Red needles have about one-tenth 

the water content of healthy green needles, and they contain about 1.5 times 

more fiber (Jolly and others 2012a).

Changes in the composition and flammability of pine needles in red-stage 

forests translate into different fire behavior. Crews on the 2012 Halsted Fire in 

southwestern Idaho observed unusual fire behavior, including passive, active, 

and independent crown fire. Fire spots even ignited canopy fuels in the absence 

of surface fire. They also noted rapid transition of surface to crown fires where 

needles of green and red-stage trees comingled in the canopy (Jenkins and others 

2014).

Fire managers both in Canada and the United States have observed rapid crown 

fire ignition in red-stage forests and spot fires up to a quarter-mile away from 

Figure 3.2. Physics-based fire models such 

as FIRETEC (pictured here) simulate fire 

spread in three dimensions and at much 

higher resolution than standard fire 

models. These detailed models are useful 

for exploring how disturbances, such as 

MPB outbreaks, affect fuel loads and fire 

behavior (figure by Russ Parsons, USDA 

Forest Service).

4 This research finding reinforces material presented in Research Finding 4 of Chapter 4.

• Larger safety zones may be required for fire operations in red-stage forests due 

to the larger heat release.

• Ground operations might not be feasible due to longer flame lengths.

• Spotting distances can be greater than usual during fires in red-stage forests.

Management 

Implications
22 USDA Forest Service RMRS-P-70. 2014.

torching red-stage trees (Schroeder and Mooney 2012). For example, the 2011 

Saddle Complex Fire made a sustained crown fire run of 17,000 acres along 

the Montana-Idaho border in a relatively short time, mostly through beetle-kill 

fuels. Spotting distances were likely greater than 1 mile (Matt Jolly, USDA Forest 

Service, pers. obs.). One game-changing effect is that embers from red-stage 

tree crowns might potentially ignite other red-stage trees. This mechanism has 

the potential to dramatically increase crown fire spread rates.

Research finding #3: Fire hazards and behavior are more uncertain when 

trees turn gray and fall down.5

Beetle-attacked fuels can alter transitions from surface to crown fire in unpredictable ways, especially during the “gray stage.” Trees have dropped their 

needles but they are still vertical during this relatively persistent stage (≥10 

years). Green and red trees are often intermixed throughout forests in the gray 

stage.

Very few researchers have explored fire behavior in gray-stage forests and forests 

with fallen snags. A common assumption at the beginning of the MPB epidemic was 

that the flammability of trees would decrease after their needles fall off. However, 

fire managers in Canada reported that standing gray-stage trees shed bark that could 

Figure 3.3. Comparison 

of heat released by 

consumption of a redstage tree and a healthy, 

green tree as modeled 

with the Wildland-Urban 

Interface Fire Dynamics 

Simulator (WFDS). Both 

trees have identical fuel 

properties except that the 

red-stage tree has lower 

foliar moisture content 

(FMC). The maximum rate 

of heat release is greater 

and occurs sooner for the 

red-stage tree. This rapid, 

intense heat release has 

important implications 

for crown fire dynamics 

(figure by Russ Parsons, 

USDA Forest Service, 

unpublished data).

5 This research finding reinforces material presented in Research Finding 4 of Chapter 4.

• Fire behavior is less predictable in gray-stage forests, calling for more cautious 

and judicious deployment of ground resources during fire operations.

• In the absence of fuels reduction treatment, windthrown snags will cause a >5-

fold increase in the coarse surface fuels after the gray stage.

• Falling snags and abundant logs during the “dead and downed stage” pose 

serious hazards to firefighters and slow fire line production rates.

Management 

Implications

100,000

80,000

60,000

40,000

20,000

0

Heat release rate (kW)

Simulation time (seconds)

0 18 36 54 72 90 108 126 144 162 180

FMC = 15%

Red phase tree,

FMC = 100%

Green healthy tree,
USDA Forest Service RMRS-P-70. 2014. 23

generate embers and increase spot fire occurrence (Schroeder and Mooney 2012). 

Spot fires from gray-stage stands have been recorded as far as a half-mile away (Dana 

Hicks, British Columbia Forests, Lands and Natural Resource Operations, pers. obs.)

Research suggests that fire hazards and behavior will change after the gray-stage 

as snags drop to the ground. Collins and others (2012) estimated that windthrown 

snags will cause a >5-fold increase in the coarse surface fuels in beetle-killed stands 

with no fuels reduction treatment. Wind speeds are likely to increase throughout the 

forest, fanning fast fires through accumulations of dry fuels (Linn et. al 2013). A higher 

prevalence of open canopies and coarse surface fuel loads are likely to increase 

surface fireline intensities. These changes could facilitate active crown fires at lower 

wind speeds across all moisture scenarios in gray-stage or dead-and-downed stands, 

even 30 years after a MPB attack (Schoennagel and others 2012). Falling snags and 

jack-straw logs are serious hazards for firefighters. In addition, fire line production 

rates drop when more logs need cutting (Page 2013). Fires in these forests may grow 

exceptionally large due to an unwillingness to put firefighters at risk.

Research finding #4: The intensity and rate of MPB attacks influence the 

risk of crown fires.

Scientists at the Rocky Mountain Research Station and their partners are using 

physics-based models to explore how the trajectory of MPB outbreaks might impact 

fire spread. They developed a simple probabilistic model of MPB spread, in which 

beetles spread from an initial start location to adjacent trees over time. Two factors 

affect the success of MPB attacks in this simple model: distance between trees and 

tree diameter. Beetles are known to preferentially attack larger host trees as they 

provide greater food value (Chapter 5).

The researchers compared two outbreak trajectories: (1) “low and slow” outbreaks, where successful attacks start with a small number of trees dispersed 

throughout the stand, and (2) “high and fast” outbreaks, where successful 

attacks start with a larger number of trees and spreads more rapidly among 

trees (Fig. 3.4). The “low and slow” case is similar in many ways to an endemic 

MPB outbreak, while the “high and fast” case is more representative of a MPB 

epidemic.

• Expect more intense fire behavior (e.g., greater fireline intensities, more rapid 

transitions from surface to crown fires, and longer spotting distances) in stands 

with a greater portion of beetle-killed trees, especially of those in the red-stage.

• Forests experiencing low-level and prolonged (“low and slow”) tree mortality 

might burn less intensely than forests with “high and fast” mortality. However, 

fire hazards are likely to remain elevated for a longer period of time following 

“low and slow” MPB outbreaks.

• Fuel treatments in the near term should focus on reducing hazards around 

priority infrastructure. Beetle-altered fire behavior and the scale of the 

epidemic make it less likely that ground operations can defend critical 

infrastructure during future wildfires.

Management 

Implications
24 USDA Forest Service RMRS-P-70. 2014.

The two outbreak trajectories resulted in different spatial patterns of tree mortality and had different implications for fire behavior. The “high and fast” case 

resulted in higher rates of spread (Fig. 3.5) and more intense fire behavior due to 

the higher proportion of red-stage trees. These findings are consistent with other 

researchers who found that crown fire intensity and canopy fuel consumption 

are strongly related to the percentage of red-stage trees in a stand (Hoffman and 

others 2012).

More intense fires might be possible in stands experiencing “high and fast” MPB 

outbreaks, but fire hazards are likely to decline sooner than in stands experiencing “low and slow” outbreaks. This is due to disrupted continuity of canopy 

fuels as trees lose their needles during the gray stage. More rapid rates of tree 

mortality for the “high and fast” scenario result in a relatively synchronous loss 

of needles and fine branches. In contrast, the red-stage persists over a longer 

period of time for “low and slow” outbreaks (Russ Parsons, USDA Forest Service, 

unpublished data).

As time continued in the model and canopy fuels dropped to the surface, wind 

speeds increased in both the “low and slow” and “high and fast” simulations 

due to less resistance from tree canopies (Fig. 3.5; Schoennagel and others 2012; 

Jenkins and others 2014). This change may result in faster surface fires. More 

work is needed to understand these interacting factors.

Research finding #5: Many questions remain about potential impacts of 

the MPB epidemic on forest fuels and fire behavior.

Despite two review papers (Hicke and others 2012; Jenkins and others 2014), 

our understanding of post-epidemic fire behaviors continues to be fraught with 

Figure 3.4. Forest Service researchers developed a simple 

model to examine how the rate and intensity of MPB 

outbreaks might change fuels and fire behavior over time. 

The “low and slow” scenario involved a slower rise in the 

proportion of red-stage trees, peaking below 20 percent 

of trees around year 7. The rapid mortality pulse in the 

“high and fast” scenario resulted in 40 percent of redstage trees by year two, with most of these trees entering 

the gray stage by year 4. Each dot represents a tree 

and the color corresponds to the stage of MPB-induced 

mortality (green, yellow, red, and grey stages). (Figure by 

Russ Parsons, USDA Forest Service, unpublished research).

“Low and slow” MPB outbreak

“High and fast” MPB outbreak

2 yrs post-outbreak 4 yrs post-outbreak
USDA Forest Service RMRS-P-70. 2014. 25

contradictions. For example, one finding is that MPB outbreaks do not necessarily lead to an increased risk of active crown fire (Simard and others 2012). This 

seems counter-intuitive given the large amounts of dry fuels in these forests. 

Contradictory research findings arise because many interacting factors influence 

post-epidemic fire behavior. These factors include:

• The rate and intensity of a MPB outbreak over space and time (see Research 

finding #4). MPB-affected stands are often mixtures of green, red, and gray 

trees. Mixing causes greater variability in the continuity of canopy fuels, 

which might reduce the potential of active crown fires (Hicke and others 

2012; Jenkins and others 2014).

• Different pre-outbreak compositions and structures. Fuel loads and 

distributions are less affected in stands with a lower proportion of pines and/

or a lower proportion of beetle-killed pines (Schoennagel and others 2012).

• Lower canopy bulk densities of trees killed by the MPB. This factor might 

moderate hazards from more abundant fine surface fuels, leading to less 

intense crown fire behavior (Hicke and others 2012). Alternatively, greater 

wind speeds in gray-stage forests might promote active crown fires (Research 

finding #4; Schoennagel and others 2012; Jenkins and others 2014).

• Specific weather conditions largely impact post-outbreak fire potentials. The 

risk of severe wildfire is likely high during a drought in dense pine forests, 

regardless of outbreak status (Schoennagel and others 2012).

Figure 3.5. Potential effects of “low 

and slow” versus “high and fast” 

MPB outbreaks as modeled with 

the Wildland-Urban Interface 

Fire Dynamics Simulator 

(WFDS). Peak rates of spread 

are potentially greater for “high 

and fast” outbreaks due to the 

abundance of red-stage trees. As 

trees fall to the ground, potential 

wind speeds increase over time 

(Russ Parsons, USDA Forest 

Service, unpublished research).

with the Wildland-Urban Interface Fire Dynamics Simulator (WFDS). Peak rates of spread are 

potentially greater for “high and fast” outbreaks due to the abundance of red-stage trees. As trees 

fall to the ground, potential wind speeds increase over time (Russ Parsons, USDA Forest Service,

unpublished research).
26 USDA Forest Service RMRS-P-70. 2014.

Literature cited

Collins, B.J., C.C. Rhoades, M.A. Battaglia, and R.M. Hubbard. 2012. The effects 

of bark beetle outbreaks in forest development, fuel loads, and potential 

fire behavior in salvage logged and untreated lodgepole pine forests. Forest 

Ecology and Management 284:260-268.

Hicke, J.A., M.C. Johnson, J.L Hayes, and H.K. Priesler. 2012. Effects of bark 

beetle-caused tree mortality on wildfire. Forest Ecology and Management 

271:81-90.

Hoffman, C., P. Morgan, W. Mell, R. Parsons, E.K. Strand, and S. Cook. 2012. 

Numerical simulation of crown fire hazard immediately after bark beetlecaused mortality in lodgepole pine forests. Forest Science 58(2):178-188.

Hoffman, C.M., C.H. Sieg, P. Morgan, W. Well, R. Linn, C. Stevens-Rumann, 

J. McMillin, R. Parsons, and H. Maffei. 2013. Progress in understanding 

bark beetle effects on fire behavior using physics-based models. 

Technical Brief CFRI-TB-1301. Colorado State University, Colorado 

Forest Restoration Institute, Fort Collins, CO. 10 pp. [online] URL: http://

coloradoforestrestoration.org/wp-content/uploads/2014/01/2013_Hoffmanetal_PhysicsBasedModels.pdf.

Jenkins, M.J., J.B. Runyon, C.J. Fettig, W.G. Page, and B.J. Bentz. 2014. 

Interactions among the mountain pine beetle, fires, and fuels. Forest Science 

60. [online] URL: http://dx.doi.org/10.5849/forsci.13-017.

Jolly, W.M., R.A. Parsons, A.M. Hadlow, G.M. Cohn, S.S. McAllister, J.B. Pop, R.M. 

Hubbard, and J.F. Negron. 2012a. Relationships between moisture, chemistry, 

and ignition of Pinus contorta needles during the early stages of mountain 

pine beetle attack. Forest Ecology and Management 269:52-59.

Jolly, W.M., R.A. Parsons, J.M. Varner, B.W. Butler, K.C. Ryan, and C.L. Gucker. 

2012b. Do mountain pine beetle outbreaks change the probability of active 

crown fire in lodgepole pine forests? Ecology 93(4):941-946.

Linn, R.R., C.H. Sieg, C.M. Hoffman, J.L. Winterkamp, and J.D. McMillin. 2013. 

Modeling wind fields and fire propagation following bark beetle outbreaks in 

spatially-heterogeneous pinyon-juniper woodland fuel complexes. Agricultural 

and Forest Meteorology 173:139-153.

Page, W.G., M.E. Alexander, and M.J. Jenkins. 2013. Wildfire’s resistance to 

control in mountain pine beetle-attacked lodgepole pine forests. Forestry 

Chronicle Volume 89(6):783-794.

• How do vertical snags during the gray-stage influence rates of spread and fire 

line intensity?

• What is the timing and rate of snag-fall, and how does this affect changes in fuel 

loads over time?

• To what degree do changes in microclimate during different post-epidemic 

stages influence fire behavior?

• What impacts will heavy accumulations of dead and downed woody fuels have 

on fire line construction, holding operations, and safety zone adequacy?

Remaining

Questions &

Knowledge Gaps
USDA Forest Service RMRS-P-70. 2014. 27

Schoennagel, T., T.T., Veblen, J.F. Negron, and J.M. Smith. 2012. Effects of 

mountain pine beetle on fuels and expected fire behavior in lodgepole 

pine forests, Colorado, USA. PLoS One 7:e30002. [online] URL: http://www.

plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030002.

Schroeder, D. and C. Mooney. 2012. Fire behavior in simulated mountain 

pine beetle-killed stands. Final Report. FPInnovations, Wildfire Operations 

Research, Hinton, Alberta. 17 pp. [online] URL http://wildfire.fpinnovations.

ca/64/ArcherMPB_Final.pdf.

Simard, M., W.H. Romme, J.M Griffin, and M.G. Turner. 2011. Do mountain pine 

beetle outbreaks change the probability of active crown fire in lodgepole pine 

forests? Ecological Monographs 81:3-24.

USDA Forest Service. 2011. Beetle fact sheet. U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Region, Golden, CO. 2 pp. [online] URL: 

http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5337223.pdf.

Meet the chapter presenters and authors

Matt Jolly works for the Rocky Mountain Research 

Station as a Research Ecologist with the Missoula Fire 

Sciences Lab. Matt served six years in the United States 

Air Force as a Satellite Communications Technician, and 

he earned a Ph.D. in Forestry from the University of 

Montana in 2004. Matt focuses his research on linking plant 

physiological processes with combustion and fire behavior 

characteristics and understanding the roles that live 

fuels play in current, operational fire behavior prediction 

systems. He can be reached at mjolly@fs.fed.us; 406-329-

4848.

Paul Langowski is the Branch Chief for Fuels and Fire 

Ecology with the Rocky Mountain Region of the Forest 

Service. He has program leadership responsibility for fuels 

management and fire use programs on National Forests 

and Grasslands lands in Colorado, Wyoming, South Dakota, 

Nebraska and Kansas. Paul also serves as the Forest Service 

representative to the Fuels Management Committee 

and Fire Use Sub-Committee of the National Wildfire 

Coordinating Group, and he is vice-chair of the Governing 

Board for the Joint Fire Science Program. Paul can be 

reached at plangowski@fs.fed.us; 303-275-5307.

Megan Matonis is a Ph.D. student at Colorado State 

University and a graduate student cooperator with the 

Science Application & Integration staff at the Rocky 

Mountain Research Station. Reach Megan at mmatonis@

fs.fed.us; 970-498-1342.

Sue Miller is a contract science writer for the Rocky 

Mountain Research Station. She received her Ph.D. in 

ecology from the University of Georgia. Sue can be reached 

at millroad@comcast.net.

Russ Parsons works for the Rocky Mountain Research 

Station as a Research Ecologist with the Missoula Fire 

Sciences Lab. He specializes in simulation modeling and 

spatial analysis, with a focus on the impact of fuel loads 

and arrangements on fire behavior. Russ received his Ph.D. 

in Forestry from the University of Montana in 2007. Reach 

Russ at rparsons@fs.fed.us; 406-329-4872.
28 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 29

Chapter 4—Forests in transition: Post-epidemic vegetation 

conditions

Authors: Rob Hubbard, Michael Battaglia, Chuck Rhoades, Jim Thinnes, Tom Martin, Jeff 

Underhill, and Mark Westfahl

Presenters: Michael Battaglia, Chuck Rhoades, Jim Thinnes, Tom Martin, Jeff Underhill, and 

Mark Westfahl

Introduction

More than 23 million acres of lodgepole pine forests across the western U.S. have experienced overstory mortality following the recent mountain pine beetle (MPB) epidemic (USDA Forest Service 2013). 

Unknowns regarding the immediate and long-term consequences of the epidemic challenge the ability of managers to make informed decisions aimed at 

sustaining forest health and delivery of ecosystem services. There is a large body 

of research regarding the recovery of lodgepole pine forest following fire and 

logging; however, the trajectory of stand development in beetle-killed forests is 

poorly understood. Research presented in this webinar 

aims to better understand forest recovery following the 

MPB epidemic, including the impacts of management 

options on regeneration, fuel loads, and potential fire 

behavior.

Lodgepole pine forests in the central and southern 

Rocky Mountains can be broadly classified into two 

main types: pure lodgepole pine and mixed-species 

lodgepole pine stands (Fig. 4.1). Pure lodgepole stands 

are those where the majority of the overstory is composed of lodgepole pine, and understory vegetation and 

advanced regeneration is sparse. Pure lodgepole pine 

forests generally exist on drier and warmer landscape 

positions and are also found in frost pockets. Mixedspecies lodgepole pine stands generally exist on wetter 

sites and have a mixture of overstory species including 

lodgepole pine, Engelmann spruce, subalpine fir, and/or 

quaking aspen. The relative percentage of these species 

depends on a variety of factors, including site conditions 

and disturbance history. Mixed-species lodgepole pine 

stands usually have significant advance regeneration 

that reflects overstory composition.

Figure 4.1. Lodgepole pine forests in the central and southern 

Rocky Mountains can be broadly classified into two main 

types: pure lodgepole pine (top), typically occurring on drier 

sites, and mixed-species lodgepole pine stands (bottom), 

often found on wetter sites (photos courtesy of USDA Forest 

Service).
30 USDA Forest Service RMRS-P-70. 2014.

The MPB has caused significant overstory mortality in both pure and mixedspecies lodgepole pine stands. The original stand structure, species composition, 

and management treatments will influence the post-beetle trajectory of forest 

recovery in these ecosystems.

Research findings

Research finding #1: Research and management observations in Colorado 

and Wyoming suggests there is adequate regeneration in beetle-affected 

forests to ensure forest recovery.

Future forest growth trajectories in MPB affected forests may differ substantially from stands that have experienced disturbance from wildfire or logging. 

In beetle-killed lodgepole pine forests, pine establishment can be inhibited by 

limited seed source and/or the absence of exposed mineral soil. The uncertainty 

of forest growth trajectories has led to a strong research effort to evaluate the 

role of seedling recruitment and advance regeneration in the recovery of beetlekilled forests.

Multiple studies suggest that forests will recover in the wake of this MPB 

epidemic:

• Pelz and Smith (2012) re-sampled pure and mixed species lodgepole pine 

stands that had experienced a MPB outbreak in the 1980’s. Thirty years 

following the outbreak, pure lodgepole pine stands had recovered 91 percent 

of pre-mortality basal area and 93 percent of overstory tree density. In 

many stands, the dominant species in the understory switched from pine to 

subalpine fir and aspen. In mixed-species stands, basal area and overstory 

tree density remained significantly reduced, and subalpine fir and Engelmann 

spruce continued to dominate the understory.

• Collins and others (2011) sampled 24 mixed-species lodgepole pine forests in 

northern Colorado that had been impacted by the recent MPB epidemic. They 

found that average seedling recruitment and advance regeneration exceeded 

regional stocking requirements of 150 trees/acre (Fig. 4.2).

• Research in Rocky Mountain National Park suggests that remaining live trees 

and understory saplings are sufficient to ensure forest recovery, in spite of 

an average reduction in overstory basal area of 64 percent. Residual live 

trees, saplings, and seedlings averaged 1,600 stems/acre in both pure and 

mixed-species stands, with a slight increase in the abundance of subalpine fir, 

Engelmann spruce, and aspen (Diskin and others 2011).

• Across the Medicine Bow Range in Wyoming, advance regeneration of 

lodgepole pine exceeded acceptable stocking levels (780 stems/acre) in 19 of 

20 pure and mixed lodgepole pine stands following the current MPB epidemic 

(Kayes and Tinker 2012).

• Tree planting is unnecessary in many stands impacted by the MPB. Advanced 

regeneration and seedling recruitment are adequate to ensure recovery to preepidemic basal areas.

• Some mixed-species lodgepole pine forests may experience a shift in their 

dominant tree species from lodgepole pine to subalpine fir and aspen.

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 31

Research finding #2: Residual overstory and understory trees are growing 

faster following the MPB epidemic.

The MPB caused a significant loss of lodgepole pine overstory, resulting in 

increased availability of light, water, and nutrients for surviving vegetation. 

Increased resource availability can facilitate growth and recovery of residual vegetation. Surviving trees increased growth by a factor of two to three following a 

MPB outbreak in the late 1960’s and early 1970’s in Yellowstone National Park 

(Romme and others 1986).

Preliminary research at the Fraser Experimental Forest in northern Colorado 

found increased growth in residual overstory subalpine fir and Engelmann 

spruce after the most recent MPB epidemic. In a three-year period following the 

epidemic, more than 35 percent of sampled overstory trees showed an increase 

in growth relative to ten years prior to the epidemic, and 16 percent grew faster 

than any other time during their life span. In addition, advanced regeneration of 

lodgepole pine and subalpine fir more than doubled their height growth since 

the beginning of the MPB epidemic (Collins and others 2011).

Research finding #3: Alternative management practices create a range of 

regeneration scenarios.

The current MPB epidemic has raised concern about wildfire and threats to public safety from falling trees, prompting an unprecedented management response 

in MPB impacted areas. Rates of post-epidemic timber harvesting are greater 

than at any other time since the 1970’s. However, the epidemic is so extensive 

that only about 15 percent of the landscape will be treated (Collins and others 

2010).

Figure 4.2. Density of seedlings and 

advance regeneration in harvested 

versus untreated forests across four 

MPB management areas in northern 

Colorado (figure adapted from Collins 

and others 2011).

Seedlings Advanced regeneration

Untreated Untreated

Harvested Harvested

Trees / acre

1600

1200

800

400

0

1200

800

400

0
32 USDA Forest Service RMRS-P-70. 2014.

Forest managers have a suite of management alternatives available for treating 

beetle-killed stands. These alternatives result in different amounts of aboveground structure (i.e., snags), surface roughness, and soil disturbance:

• “No action” option retains standing snags, downed wood, and maximum 

surface roughness.

• Watershed protection / delivery treatments maximize water delivery 

by retaining logging residue on site. Slash maintains surface roughness, 

increasing snow accumulation, and helps avoid soil disturbance.

• Fuel reduction treatments focus on removing snags and slash.

• Forest regeneration treatments combine slash reduction and mechanical 

scarification to enhance seedling establishment.

All four of these management options are likely to impact soil resources and 

seedling recruitment and growth. Research across four MPB management 

areas in northern Colorado found that watershed protection and water delivery 

treatments increased seedling height growth by approximately 20 percent relative to the other treatments (Chuck Rhoades and others, USDA Forest Service, 

unpublished data). This is possibly due to increased water availability. Survival 

of seedlings experimentally planted by researchers was generally greater in the 

forest regeneration treatments, but natural seedling recruitment was greater in 

fuel reduction treatments.

Treatments can also result in different species compositions in mixed-species 

lodgepole pine stands. Research in northern Colorado found that about 75 percent of new seedlings in cut areas were lodgepole pine, where about 70 percent 

of new seedlings in untreated stands were subalpine fir (Fig. 4.2; Collins and 

others 2011). Cut areas had about ten times more new pine seedlings and seven 

times more aspen sprouts than untreated stands.

Stand development projections using the Forest Vegetation Simulator (FVS) 

suggest that significant aspen sprouting will increase the proportion of aspen in 

both untreated and harvested areas. Lodgepole pine will become the dominant 

species in harvested areas after aspen declines, while subalpine fir and lodgepole pine will dominate in untreated areas a century after the MPB epidemic 

(Fig. 4.3).

• Decisions about slash retention and soil disturbance create tradeoffs between 

water delivery and seedling establishment.

Д Greater slash retention can enhance water delivery by promoting snow 

accumulation. This can enhance seedling growth, but the absence of bare 

mineral soil can inhibit seedling establishment.

Д Removal of slash and exposure of mineral soil can enhance seedling 

establishment, but it reduces surface roughness and snow accumulation.

• Fuels reduction treatments in mixed-species lodgepole pine stands might result 

in future forests dominated by lodgepole pine, whereas untreated stands might 

be dominated by subalpine fir. 

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 33

Research finding #4: Tree mortality from the MPB epidemic and postepidemic harvesting will influence fuel loads and fire behavior for many 

decades to come.6

The MPB epidemic and subsequent harvesting substantially alter fuel loads 

with potential implications for fire behavior. Salvage logging in beetle-infested 

Colorado forests is expected to affect future fires by favoring regeneration of 

pine and aspen over subalpine fir, a species with a dense crown and branches 

that extend to the ground. Abundant subalpine fir in untreated, beetle-killed 

stands could act as ladder fuels that allow fires burning on the surface to spread 

into the forest canopy.

Researchers at the Rocky Mountain Research Station explored this possibility 

using FVS and its Fire and Fuels Extension. They compared forest composition 

and fuel loads in 24 paired treated and untreated stands in northern Colorado 

and projected stand structure characteristics and potential fire behavior over the 

next 100 years (Collins and others 2012a,b). They found that:

Figure 4.3. Projected stand development based on initial observations in harvested (n = 24) and untreated stands (n = 24) 

across northern Colorado. Growth was simulated using the Forest Vegetation Simulator. Projections were based on 

observed regeneration, overstory conditions, and site index (reprinted from Collins and others 2011).

Untreated Harvested

Total

Lodgepole

Subalpine fir

Eng. spruce

Aspen

Total

Lodgepole

Subalpine fir

Eng. spruce

Aspen

Years Years

0 20 40 60 80 100 0 20 40 60 80 100

Density (trees / acre) Basal area (ft2 / acre)

0 20 40 60 80 100 0 20 40 60 80 100

2400

1600

800

0

2400

1600

800

0

180

135

90

45

0

180

135

90

45

0

6 This research finding reinforces material presented in Research Findings 2 and 3 of Chapter 3.
34 USDA Forest Service RMRS-P-70. 2014.

• Surface fuel loads (1, 10, 100, and 1000-hr size classes) were about 3 times 

greater in harvest units compared to untreated stands.

• Coarse fuel loads (≥3 inches in diameter) will accumulate over time, 

increasing the potential for larger and more severe wildfires. Higher coarse 

fuel loads increase soil heating, increase the production of airborne embers, 

and hinder fire suppression.

Differences in tree species composition and the higher fuel loads in untreated, 

beetle-killed stands create the potential for more extreme fire behavior compared with harvested areas (Fig. 4.4). Fire behavior might become more similar 

between untreated and harvested areas when trees lose their needles and 

transition into the gray-stage. However, as the forest overstory develops, abundant subalpine fir will increase the canopy bulk density and lower canopy base 

height of untreated stands. These crown conditions allow for torching at lower 

wind speeds and increase active crown fire potential during extreme weather 

(Fig. 4.5). As a result, passive crown fires (i.e., fires that ignite individual tree 

crowns but do not spread between canopies) are expected to occur in untreated 

stands under average weather conditions (i.e., 50th percentile weather). In 

contrast, surface fires are predicted for harvested areas under similar weather 

conditions (Collins and others 2012a).

• How adequate are forest growth projections from the Forest Vegetation 

Simulator, given that it was developed for stands that had not experienced 

significant bark beetle disturbances?

• How do standing dead snags and subsequent tree fall impact stand 

development over time?

• To what degree can an abundance of herbaceous vegetation in some postepidemic understories impact seedling recruitment and establishment?

• How will future disturbances from insects, diseases, and fire influence stand 

development in treated and untreated pure and mixed-species lodgepole pine 

forests?

Remaining

Questions &

Knowledge Gaps

• Fuel loads are initially greater in harvested stands, but research suggests this 

does not increase the potential for crown fires.

• Untreated stands will accumulate greater coarse fuel loads (≥3 inches in 

diameter) over time, increasing the potential for larger and more severe 

wildfires across beetle-killed landscapes. 

• Abundant subalpine fir regeneration in untreated, beetle-killed stands could act 

as ladder fuels that facilitate the transition from surface fires to crown fires. 

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 35

Figure	
  4.4.	
  Changes in surface fuel loads in harvested and untreated MPB management areas as 

estimated by the Forest Vegetation Simulator Fire and Fuels Extension. Projected changes based on 

initial observations of fuel loads in 24 untreated and 24 harvested areas across northern Colorado

(reprinted from Collins and others 2012a).

Figure 4.4. Changes in surface fuel loads in harvested and untreated 

MPB management areas as estimated by the Forest Vegetation 

Simulator Fire and Fuels Extension. Projected changes based 

on initial observations of fuel loads in 24 untreated and 24 

harvested areas across northern Colorado (reprinted from Collins 

and others 2012a).

Figure 4.5. Removing beetle-killed trees can increase surface 

fuel loads for several years following treatments, but over 

time, coarse woody fuel loads will be greater and ladder fuels 

more abundant in untreated forests. Untreated forests might 

have greater potential for crown fires in the future, increasing 

safety concerns for firefighters during fire operations (image 

of the 2010 Church’s Park Fire near Fraser, CO, courtesy of 

InciWeb).

Literature cited

Collins, B.J., C.C. Rhoades, J. Underhill, and R.M. Hubbard. 2010. Post-harvest 

seedling recruitment following mountain pine beetle infestation of Colorado 

lodgepole pine stands: A comparison using historic survey records. Canadian 

Journal of Forest Research-Revue Canadienne De Recherche Forestiere 

40:2452-2456.

Collins, B.J., C.C. Rhoades, R.M. Hubbard, and M.A. Battaglia. 2011. Tree 

regeneration and future stand development after bark beetle infestation 

and harvesting in Colorado lodgepole pine stands. Forest Ecology and 

Management 261:2168-2175.

Collins, B.J., C.C. Rhoades, M.A. Battaglia, and R.M. Hubbard. 2012a. Effects of 

salvage logging on fire risks after bark beetle outbreaks in Colorado lodgepole 

pine forests. Fire Management Today 72(3):18-22.
36 USDA Forest Service RMRS-P-70. 2014.

Collins, B.J., C.C. Rhoades, M.A. Battaglia, and R.M. Hubbard. 2012b. The effects 

of bark beetle outbreaks on forest development, fuel loads and potential 

fire behavior in salvage logged and untreated lodgepole pine forests. Forest 

Ecology and Management 284:260-268.

Diskin, M., M.E. Rocca, K.N. Nelson, C.F. Aoki, and W.H. Romme. 2011. Forest 

developmental trajectories in mountain pine beetle disturbed forests of Rocky 

Mountain National Park, Colorado. Canadian Journal of Forest ResearchRevue Canadienne De Recherche Forestiere 41:782-792.

Kayes, L.J. and D.B. Tinker. 2012. Forest structure and regeneration following a 

mountain pine beetle epidemic in southeastern Wyoming. Forest Ecology and 

Management 263:57-66.

Pelz, K.A. and F.W. Smith. 2012. Thirty year change in lodgepole and lodgepole/

mixed conifer forest structure following 1980s mountain pine beetle outbreak 

in western Colorado, USA. Forest Ecology and Management 280:93-102.

Romme, W.H., D.H. Knight, and J.B. Yavitt. 1986. Mountain pine beetle outbreaks 

in the Rocky-Mountains - Regulators of primary productivity. American 

Naturalist 127:484-494.

USDA Forest Service. 2013. Bark beetles: Summary for 2000-2012, Western U.S. 

U.S. Department of Agriculture, Forest Service, Washington, DC. 3 pp. [online] 

URL: http://www.fs.fed.us/foresthealth/technology/pdfs/MpbWestbb_

FactSheet.pdf.
USDA Forest Service RMRS-P-70. 2014. 37

Meet the chapter presenters and authors

Michael Battaglia is a Research Silviculturist and has 

been a scientist with the USFS Rocky Mountain Research 

Station since 2011. He received his Ph.D. in Forest Sciences 

from Colorado State University in 2007. Mike’s research 

interests focus on forest restoration, fuels mitigation, and 

forest resilience across multiple spatial scales. He can be 

reached at mbattaglia@fs.fed.us; 970-498-1286.

Rob Hubbard has worked as a Research Ecologist with 

the Rocky Mountain Research Station since 2005. He 

worked as a Research Ecologist for the Coweeta Hydrologic 

Lab in North Carolina after graduating with his Ph.D. 

in forest ecology from Colorado State University. Rob’s 

research explores how forests respond to disturbances and 

the role that plants play in regulating hydrologic processes. 

Reach Rob at rhubbard@fs.fed.us; 970-498-1260.

Tom Martin is the Assistant Director Renewable 

Resource Management for the Northern Region of the 

Forest Service. Tom has worked with the Forest Service 

for over 35 years in timber management, silviculture, 

environmental analysis, and forest planning. He has 

dedicated most of his career to developing forest 

conditions that meet resource objectives, including the 

use of timber harvests as a tool to meet resource, social, 

and economic needs. Tom graduated in 1978 with a B.S. 

in Forest Management, and he is a certified silviculturist. 

Reach Tom at thmartin@fs.fed.us; 406-329-3608.

Chuck Rhoades is a watershed biogeochemist and 

has been with the Rocky Mountain Research Station 

since 2003. He earned his Ph.D. in forest biogeochemistry 

and soil ecology from the University of Georgia in 1998. 

Chuck’s research interests focus on forest biogeochemical 

processes that regulate the delivery of clean water and 

sustain productive soils and forests. He can be reached at 

crhoades@fs.fed.us; 970-498-1250.

Jim Thinnes has been the Regional Silviculturist for the 

Rocky Mountain Region of the Forest Service since 2005. 

He has 30 years of experience with the Forest Service in 

environmental planning, silviculture, timber management, 

hydrology, and wildland fire suppression. He is an SAF 

Certified Forester and received his degree in natural 

resource management from Ohio State University. He has 

much on-the-ground experience with the MPB epidemic 

owing to his time on the Pike & San Isabel National Forest 

and the White River National Forest. He can be reached at 

jthinnes@fs.fed.us; 303-275-5016.

Jeff Underhill is the Forest Timber Program Manager 

and Forest Silviculturist for the Pike & San Isabel National 

Forests. Jeff has five years of experience addressing the 

effects of the MPB epidemic through his work on the Pike 

& San Isabel National Forests and Arapaho & Roosevelt 

National Forests. Jeff received his M.S. in Forestry from the 

University of Tennessee and his B.A. in History from Virginia 

Tech. He can be reached at junderhill@fs.fed.us; 719-553-

1513.

Mark Westfahl is the Timber Program Manager and 

Forest Silviculturist for the Medicine Bow-Routt National 

Forests. At the time of the Future Forest Webinar Series, 

he was a Silviculturist and Safety Coordinator for the 

Medicine Bow-Routt National Forests. Mark has worked 

in timber management for the Forest Service for over 25 

years, spending three seasons on the Arapaho & Roosevelt 

National Forests before starting on the Parks Ranger 

District of the Medicine Bow-Routt National Forests. He is 

a certified silviculturist and graduated from the University 

of Montana with a B.S. is Forest Resource Management. 

Reach Mark at mwestfahl@fs.fed.us; 970-723-8204.
38 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 39

Chapter 5—Ecological consequences of the MPB epidemic 

for habitats and populations of wildlife

Authors: Beth Hahn, Vicki Saab, Barbara Bentz, Rachel Loehman, and Bob Keane

Presenters: Beth Hahn, Vicki Saab, Barbara Bentz, Rachel Loehman, and Bob Keane

Introduction

Wildlife biologists must balance a diverse array of ecological and social 

considerations in managing species and habitats. The challenges of 

managing species and habitats in dynamic landscapes are influenced 

by diverse factors, including natural disturbances, vegetation development, and 

anthropogenic-mediated changes, such as climate change, management activities, and land use. Mountain pine beetles (MPBs) can be viewed as an ecosystem 

engineer—a species that both directly and indirectly shapes landscapes by 

altering the composition, structure, and function of ecosystems. Although native 

wildlife species co-evolved with natural disturbances such as MPB outbreaks, 

in the shorter term these changes simultaneously create and eliminate certain 

habitats. Additionally, changes to ecosystems from MPB outbreaks interact with 

other processes such as fire, nutrient cycling, and sedimentation to further alter 

habitats.

Species-specific responses are expected to vary as a function of outbreak severity, time since the peak of tree mortality, and characteristics of the species, 

including life history traits, habitat associations, and foraging requirements (Saab 

and others 2014). MPB outbreaks cause both short- and long-term changes in 

the pattern, extent, and structure of habitats, with major implications for wildlife 

populations. For example, MPBs provide an extended food resource for some 

bird species, while reducing habitat in the short term for other species, such as 

the pine squirrel.

Managing forests to anticipate or mitigate the effects of the MPB epidemic 

on wildlife species is challenging. For instance, there are critical differences 

in the operative scales for responding to MPB outbreaks and managing forest 

resources and wildlife populations. Beetle-induced tree mortality may be high 

at the stand scale (Fig. 5.1), but most vertebrate populations exist across areas 

with magnitudes much larger than a single stand or watershed. Moreover, the 

“footprint” of interacting natural disturbances such as the MPB epidemic and 

fire is enormous compared to the footprint of most land management actions 

(see Chapter 8).

Wildlife management does not proceed in isolation from other considerations 

such as timber or recreation. Projects are designed and analyzed by interdisciplinary teams, and wildlife biologists contribute to this process by adding 

elements that either improve habitat or mitigate adverse impacts. Project design 

and analysis must comply with relevant law, regulation and policy (e.g., National 

Forest Management Act, National Environmental Policy Act, and Endangered 
40 USDA Forest Service RMRS-P-70. 2014.

Species Act). Analysis requirements imposed by laws or regulations frequently 

differ from ecologically-relevant spatial and temporal scales (Ruggiero and others 1994; Block and others 2012). For instance, a Forest Service biologist will 

need to evaluate whether a 1,000-acre salvage harvest within a 15,000-acre 

project area will affect the persistence of sensitive species (e.g., black-backed 

woodpecker) at the scale of the entire National Forest. An entire National Forest 

is much larger than the home ranges for different populations of black-backed 

woodpeckers (cf. Pierson and others 2010).

In this webinar, we used a case study approach to examine the ecological consequences of the MPB epidemic for wildlife habitats and species. We presented 

different methods for comparing spatial and temporal patterns of bird diversity, 

reproduction, habitat use, persistence, and foraging in relation to the MPB 

epidemic. We also presented modeling techniques for investigating wildlife responses to large-scale disturbance.

Research findings

Research finding #1: Life history traits can help predict the impact of 

disturbances on populations and habitats of wildlife species.

Figure 5.1. Tree mortality 

from the current MPB 

epidemic in the Elkhorn 

Mountains, Helena 

National Forest. Left 

photo shows preepidemic conditions in 

2005; right photo shows 

the same site in 2010 

(photos by V. Saab and 

Barbara Bentz, USDA 

Forest Service).

• The MPB epidemic created habitat for some species and eliminated habitat for 

others. Birds that eat beetles and/or build nests in snags will likely benefit for 

several years following the epidemic, whereas foliage gleaners may have lower 

occupancy levels relative to pre-epidemic conditions.

• Responses of bird guilds to disturbance change over time as vegetation recovers 

and alters habitat suitability. 

• Areas with low, medium, and high levels of beetle-induced tree mortality 

provide habitat for different types of species.

Management

Implications

2005 

2010 
USDA Forest Service RMRS-P-70. 2014. 41

Scientists with the Rocky Mountain Research Station are examining implications 

of the MPB epidemic for habitats and populations of small land birds. Birds make 

an ideal model for evaluating wildlife responses to the MPB epidemic because 

of their high sensitivity to disturbances (Saab and Powell 2005; Saab and others 

2014). Guilds—groups of ecologically similar species—can be useful categories 

for predicting and examing bird responses to disturbance. Cavity-nesting birds 

that feed on larvae, and bark- and wood-boring insects are one guild (e.g., 

woodpeckers), while foliage-gleaning birds that nest in open cup structures are 

another guild (e.g., golden-crowned kinglet).

Responses of bird guilds to disturbance change over time as vegetation recovers and alters habitat suitability (Fig. 5.2). The first years after a disturbance 

are more favorable for cavity-nesting species because of the high abundance of 

snags for nesting. Populations of beetle-foraging specialists also peak four to five 

years after fire or MPB outbreaks due to elevated populations of bark and woodboring insects (Saab and others 2007b; Davis and others 2012). Ground and 

aerial insectivores continue to increase for at least 12 years following a wildfire, 

particularly when there is a pulse of arthropods due to nutrient release after 

fire (Saab and others 2007b). Omnivorous, shrub-nesting species select habitats 

that form as snags begin to fall and shrubs establish. Canopy-nesting species and 

foliage gleaners are the last to colonize forests after disturbance because they 

depend on dense forest overstories.

Disturbance severity also influences the habitat of different bird guilds. Most 

foliage-gleaning (e.g., chickadees) and log-foraging species (e.g., pileated 

woodpecker) are abundant in unburned habitats. Sites experiencing low- and 

Figure 5.2.

Generalized 

response of bird 

guilds to post-fire 

habitat conditions 

(figure from 

Saab and others 

2007a, modified 

from Hannon and 

Drapeau 2005).

BURN

YOUNG

MATURE

OLD 

-herb cover GROWTH

-snags fall

-understory 

 develops

-few snags

-closed canopy

-low understory 

 development

-snags

-open canopy

-understory 

 develops

Cavity-nesting

beetle-foraging

aerial insectivore Shrub-nesting

omnivore

Time in 

years 0 15 25 50 100 125

Responses change 

with time since fire

Canopy-nesting

foliage insectivore

Golden-crowned 

kinglet

Black-backed 

woodpecker 

Mountain 

bluebird

Lazuli bunting

Black-headed 

grosbeak
42 USDA Forest Service RMRS-P-70. 2014.

mixed-severity fires provide habitat for species benefiting from snag creation 

and the retention of some live trees for foraging. These species include cavitynesters that feed on pine seeds (e.g., white-headed woodpecker) and species 

that glean insects from bark of living trees. At locations subject to moderate and 

high severity fires, wood drillers (e.g., black-backed woodpeckers) and aerial 

insectivores (e.g., mountain bluebird) predominate.

Compared to post-fire conditions, data on species and guild responses to insect 

outbreaks are relatively sparse. Research in the Elkhorn Mountains on the 

Helena National Forest assessed changes in bird occupancy, nest density, and 

habitat suitability using data collected before and during the MPB epidemic 

(Mosher 2011; Saab and others 2014). Occupancy levels were substantially 

different before and during the MPB epidemic for 30 percent of the species 

measured. Bark insectivores had a strong positive response, while foliage 

gleaners had a weak negative response to the epidemic (Mosher 2011). Nest 

densities for cavity-nesting birds increased, primarily for beetle-foraging species 

(American three-toed woodpecker, hairy woodpecker, and downy woodpecker). 

In contrast, nest densities of species that do not forage on beetles remained 

similar to pre-epidemic levels (Saab and others 2014).

Researchers also modeled nesting habitat suitability for American three-toed 

woodpeckers. This species responded most favorably to the MPB epidemic in 

terms of increased occupancy and nest density. Highly-suitable habitat was 

abundant across the study area following the MPB epidemic (Vicki Saab, USDA 

Forest Service, unpublished data). With more research, habitat suitability models 

could be developed for additional species to inform management decisions that 

balance multiple objectives.

Research finding #2: Beetle-killed trees provide an important foraging 

resource for some bird species immediately following MPB outbreaks.

One of the research objectives at the Elkhorn Mountain sites was to estimate 

how long trees killed by MPBs are a foraging resource for birds. After initial 

tree attack, MPB larvae and adults develop within a tree for one year before 

emerging to attack another live tree. A large number of wood-boring insects 

subsequently infest beetle-killed trees. A single tree can provide a food resource 

for woodpeckers over several years. At the Elkhorn sites, preliminary results 

show that woodpeckers preferentially foraged on beetle-attacked trees with 

large diameters (>9” dbh). These trees are of greatest foraging value in the first 

4-5 years following an attack, although infested trees can provide forage up to 

• Bird species that eat beetles can actually lower the local density of MPB in years 

with endemic and post-endemic population sizes.

• Large diameter snags are particularly important foraging resources for 

woodpeckers, with the greatest foraging value occurring 4-5 years after MPB 

outbreaks.

• Anywhere from 70-90 percent of snags fall within 5 years of a MPB outbreak. 

Higher fall rates are generally associated with warmer and wetter conditions.

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 43

14 years after their death (Barbara Bentz, USDA Forest Service, unpublished 

data). Beetle-foraging bird species can actually influence the local density of 

some MPB populations during endemic and post-epidemic population phases 

(Fayt and others 2005).

The snag-fall rate will influence the time that a tree is a foraging resource for 

birds. There is high variability in snag persistence following beetle-induced 

tree death. Anywhere from 70-90 percent of snags fall within 5 years of a MPB 

outbreak. The rate that trees fall may be related to climate, soil moisture, tree 

species, and the speed of bole decay. Higher fall rates are generally associated 

with warmer and wetter conditions, as well more open forest structures due to 

lower wind resistance (Mitchell and Preisler 1998; Lewis and Hartley 2006).

Research finding #3: Models can help project changes in wildlife habitat 

over time and at different spatial scales.

Wildlife managers rely on empirical data and model predictions to estimate 

wildlife population sizes and habitat suitability. Setting wildlife management 

priorities for a particular landscape, such as recovery efforts for federally-listed 

species, requires information at different spatial and temporal scales. Research 

on implications of the MPB for wildlife can help managers prioritize critical restoration projects, inform project design criteria (i.e., retention, thinning, salvage, 

and replanting), and identify sites and habitats that should be left in an “unmanaged” state.

Modeling allows managers and researchers to examine interactions among 

ecological processes (e.g., the MPB epidemic, climate change, and wildfire) and 

other landscape influences (e.g., management actions and land use changes), 

and the effect of these dynamic interactions on wildlife habitat. The FireBGCv2 

model is useful to exploring long-term trends in landscape conditions, such as 

the quality of bull trout habitat under different disturbance regimes (Keane and 

others 2011; Holsinger and others in review).

• Model projections at landscape scales are necessary for species that have large 

home ranges or migrate throughout the year. Smaller-scale projections are 

more appropriate for species that depend on specific within-stand structures 

and composition.

• The future is not set in stone, so models can help assess the impact of different 

management decisions under a range of potential conditions (e.g., climate 

scenarios).

• Linking site-specific research projects with broader-scale monitoring programs 

will be essential to derive robust, multi-scale inferences while also leveraging 

limited resources. 

• Understand the assumptions and limitations of models. For example, some 

datasets are less reliable than others, and this can greatly influence the 

reasonableness of model predictions. 

• Qualitative modeling approaches, such as scenario planning, are often helpful 

when future conditions are dynamic and largely unknown and/or when 

quantitative data is not available.

Management

Implications
44 USDA Forest Service RMRS-P-70. 2014.

Models are useful for projecting wildlife habitat at sites or times for which there 

are no empirical observations, and for exploring different landscape configurations (e.g., connectivity and management treatments) over large spatial and long 

temporal scales. For example, researchers used an extensive stream network 

database to develop a model of suitable stream habitat for bull trout, a threatened species under the Endangered Species Act, under current and projected 

climate changes (Rieman and others 2007; Isaak and others 2010). This model 

is especially helpful to managers because it provides robust inference at both 

watershed and landscape scales.

Modeling efforts can describe a range of potential future conditions, such as 

multiple climate scenarios. For example, researchers can couple models of MPB 

survival with projections of temperatures in future decades to predict future 

MPB populations across the western United States (Bentz and others 2010). 

Managers can use simulated future conditions as tools for multi-decadal planning and conservation.

In addition, models can assess ecosystem responses at different spatial and process scales, such as landscape-scale shifts in species abundance, composition, 

or carbon balance and stand-level vegetation recovery resulting from dynamic 

climate-vegetation-disturbance interactions (Fig. 5.3). Forest Service researchers 

and managers are currently developing an integrated, dynamic model to predict 

changes in bird habitat suitability based on the likelihood of fire and MPB outbreaks. The model incorporates the role of temperature on the developmental 

phenology of the MPB, as well as the influence of climate on host tree defenses.

Understanding the assumptions and limitations of models, including appropriate 

spatial and temporal scales, is critical to management applications. Uncertainty 

Figure 5.3. Climate-driven changes in vegetation types and fire regimes simulated using the FireBGCv2 model for the East 

Fork of the Bitterroot River, MT (Holsinger and others in review).

20th century climate Warmer-wetter Hotter-drier

Vegetation types

Cumulative 

number of fires

Ponderosa pine

Douglas-fir

Lodgepole pine

Subalpine fir

Eng. spruce

Aspen

Shrubs

Grasses

Max = 30 Max = 34 Max = 79

0 6 12 18 24 30 0 7 14 21 28 35 0 16 32 48 64 80
USDA Forest Service RMRS-P-70. 2014. 45

in model predictions can be especially high for short-term projections over large 

landscapes. In addition, the resolution of available data might be too coarse for 

predicting changes in habitat components important to wildlife species (e.g., 

distribution of snags).

Habitat suitability indices can inform short-term management decisions, but 

mechanistic models that incorporate landscape dynamics are needed to support 

long-term planning. For example, models have been developed to simulate the 

effects of climate change scenarios on the distribution of 135 tree species and 

150 bird species in the eastern United States (Iverson and others 2011). These 

models are helpful for projecting the locations of high-quality habitats under 

potential future conditions. However, they should only be applied at very coarse 

scales, much larger than the typical management project scale.

Literature cited

Bentz, B.J., R. Jacques, C.J. Fettig, E.M. Hansen, J.L. Hayes, J.A. Hicke, R.G. Kelsey, 

R.G., J.F. Negrón, and S.J. Seybold. 2010. Climate change and bark beetles of 

the Western United States and Canada: Direct and indirect effects. BioScience 

60:602-613.

Block, W.M., V.A. Saab, and L. Ruggiero. 2012. Putting science into action on 

Forest Service lands. Pp 49-62 in J.P. Sands, S. J. DeMaso, M. J. Schnupp, and 

L. A. Brennan (eds). Wildlife Science: Connecting Research with Management. 

CRC Press: Boca Raton, FL.

Davis, R.S., S. Hood, and B.J. Bentz. 2012. Fire-injured ponderosa pine provide 

a pulsed resource for bark beetles. Canadian Journal of Forest Research 

42:2022-2036.

Fayt, P., M.M. Machmer, and C. Steeger. 2005. Regulation of spruce bark beetles 

by woodpeckers – a literature review. Forest Ecology and Management 

206:1-14.

Hannon, S.J. and P. Drapeau. 2005. Bird responses to burning and logging in the 

boreal forest of Canada. Studies in Avian Biology 30:97-115.

Holsinger, L.R., R.E. Keane, D. Isaak, L. Elby, and M. Young. In review. Stream 

temperatures increase under future climates regardless of fire management 

for a northern Rocky Mountains watershed using simulation modeling. 

Submitted to Ecological Modeling. 

• Our understanding of wildlife responses to the MPB epidemic is much more 

limited than our understanding of post-epidemic vegetation responses and fire 

hazards responses. Managers and researchers need to identify information gaps 

and uncertainties.

• Scenario planning and simulation modeling are useful approaches to support 

decision-making in the face of future dynamic ecosystem conditions.

• Managers and researchers from different disciplines need to collaborate to 

develop models that incorporate multiple disturbance trajectories, different 

patterns of vegetation change, and alternative management treatments to 

estimate a range of possible future conditions (see Chapter 8).

Management

Implications
46 USDA Forest Service RMRS-P-70. 2014.

Isaak, D.J., C.H. Luce, B.E. Rieman, D.E. Nagel, E.E. Peterson, D.L. Horan, S. 

Parkes, and G. Chandler. 2010. Effects of climate change and wildfire on 

stream temperatures and salmonid thermal habitat in a mountain river 

network. Ecological Applications 20:1350-1371.

Iverson, L.R., A.M. Prasad, S.N. Matthews, and M.P. Peters. 2011. Lessons 

learned while integrating habitat, dispersal, disturbance, and life-history traits 

into species habitat models under climate change. Ecosystems 14:1005-1020.

Keane, R. E., R. A. Loehman, and L. M. Holsinger. 2011. The FireBGCv2 landscape 

fire and succession model: A research simulation platform for exploring fire 

and vegetation dynamics. General Technical Report RMRS-GTR-255. U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station, 

Fort Collins, CO. 137 pp.

Lewis, K.J. and I.D. Hartley. 2006. Rate of deterioration, degrade and fall of trees 

killed by mountain pine beetle. BC Journal of Ecosystems and Management 

7:11-19

Mitchell, R.G. and H.K. Preisler. 1998. Fall rate of lodgepole pine killed by the 

mountain pine beetle in central Oregon. Western Journal of Applied Forestry 

13:23-26.

Mosher, B.A. 2011. Avian community response to a mountain pine beetle 

epidemic. Montana State University, Bozeman, MT. 61 pp.

Pierson, J.C., F.W. Allendorf, V. Saab, P. Drapeau, and M.K. Schwartz. 2010. Do 

male and female black-backed woodpeckers respond differently to gaps in 

habitat? Evolutionary Applications 3:263-278.

Rieman, B., D. Isaak, S. Adams, D. Horan, D. Nagel, C. Luce, and D. Myers. 2007. 

Anticipated climate warming effects on bull trout habitats and populations 

across the Interior Columbia River Basin. Transactions of the American 

Fisheries Society 6:1552-1565.

Ruggiero, L.F., G.D. Hayward, and J.R. Squires. 1994. Viability analysis in 

biological evaluations: Concepts of population viability analysis, biological 

population, and ecological scale. Conservation Biology 8:364-372.

Saab, V.A. and H.D.W. Powell. 2005. Fire and avian ecology in North America: 

Process influencing pattern. Studies in Avian Biology 30:1-13.

Saab, V., W. Block, R. Russell, J. Lehmkuhl, L. Bate, and R. White. 2007a. Birds 

and burns of the Interior West: Descriptions, habitats, and management in 

western forests. General Technical Report PNW-GTR-712. U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR. 

23 pp.

Saab, V.A., R.E. Russell, and J.G. Dudley. 2007b. Nest densities of cavity-nesting 

birds in relation to postfire salvage logging and time since wildfire. Condor 

109:97-108.

Saab, V.A., Q. Latif, M. Rowland, T. Johnson, A. Chalfoun, S. Buskirk, J. Heyward, 

and M. Dresser. 2014. Ecological consequences of mountain pine beetle 

outbreaks for wildlife in western North American forests. Forest Science 60. 

[online] URL: http://dx.doi.org/10.5849/forsci.13-022. 
USDA Forest Service RMRS-P-70. 2014. 47

Meet the chapter presenters and authors

Barbara Bentz has served as a Research Entomologist 

with the Rocky Mountain Research Station in Logan, UT 

since 1991. Her research interests include the biology, 

ecology, and management of MPBs. Barbara’s recent 

research has focused on modeling climate change 

influences on MPBs populations and the interactions 

between fire and MPBs. Barbara can be reached at 

bbentz@fs.fed.us; 435-755-3577.

Beth Hahn is the Branch Chief of Wilderness Science 

at the interagency Aldo Leopold Wilderness Research 

Institute, in Missoula, MT. Previously, she worked as the 

Regional Wildlife Ecologist for the Northern Region of the 

Forest Service stationed in Missoula, MT. In that capacity, 

she worked on a variety of multi-scale inventory and 

monitoring programs, habitat analyses, and plan revision 

and amendments. Reach Beth at bhahn@fs.fed.us; 406-

542542-3244.

Bob Keane is a Research Ecologist with the Rocky 

Mountain Research Station at the Missoula Fire Sciences 

Lab. Bob’s recent research includes 1) developing ecological 

computer simulation models for the exploring landscape, 

fire, and climate dynamics, and 2) investigating the ecology 

and restoration of whitebark pine. Reach Bob at rkeane@

fs.fed.us; 406-329-4846.

Rachel Loehman is a Research Ecologist with the Rocky 

Mountain Research Station at the Missoula Fire Sciences 

Lab. Rachel’s research includes spatial modeling of climate 

change effects on ecosystem processes, climate drivers 

of wildfire, and disturbance ecology. Reach Rachel at 

raloehman@fs.fed.us; 406-829-7386.

Vicki Saab is a Research Wildlife Biologist with the Rocky 

Mountain Research Station in Bozeman, MT. Her research 

interests include disturbance ecology and avian ecology, 

with an emphasis on cavity-nesting birds and other small 

landbirds. Her research focuses on avian distributions and 

demographics in relation to wildfires, MPB epidemics, and 

forest restoration activities. Vicki can be reached at vsaab@

fs.fed.us; 406-994-5032.
48 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 49

Chapter 6—Beetles among us: Social and economic impacts 

of the MPB epidemic

Authors: Krista Gebert, Greg Jones, Patty Champ, Mike Czaja, Chuck Oliver, Paul E. Cruz, and 

Jessica Clement

Presenters: Krista Gebert, Greg Jones, Patty Champ, Mike Czaja, Chuck Oliver, Paul E. Cruz, 

and Jessica Clement

Introduction

Healthy forest ecosystems provide many goods and services that are vital 

to human well-being. When forest ecosystems are impacted by disturbances, such as the widespread mountain pine beetle (MPB) epidemic, 

the services provided by these ecosystems are also affected. Likewise, management in response to large-scale forest disturbances impacts both the natural 

and human environment. These management actions are costly in terms of the 

amount of taxpayer dollars required to carry them out and in terms of their 

opportunity costs, especially in areas lacking economically-viable uses of beetlekilled timber. In the budget-constrained environment of land management 

agencies, more money spent dealing with dead and dying trees often means 

less money spent on services like building trails, improving wildlife habitats, and 

ecological restoration.

To date, management responses to the MPB epidemic have focused on public 

safety, with hazardous tree removal around public campsites, roads, and infrastructure given high priority. However, the MPB epidemic has numerous social 

and economic impacts beyond human safety. For example, the MPB epidemic 

affects consumptive uses of the forest, such as timber and biomass production, 

as well as non-consumptive uses, such as tourism and recreation. The MPB epidemic can also impact other services that the forest provides to humans, such as 

water quality or quantity and soil stability. Property values can also be impacted 

by increased risk of wildfires and/or the loss of scenic beauty.

The widespread nature of the MPB epidemic—affecting large portions of 

Colorado, Idaho, Montana, and Wyoming—exacerbates social and economic 

costs since both more area and more people are affected. For example, the MPB 

attack might have decimated favorite nearby recreation sites as well as fartherflung recreation areas, leaving people without alternatives. The extent of the 

epidemic makes it impossible to mitigate all hazards everywhere. Land management agencies must use a triage approach to prioritize hazardous tree removal 

and fuel treatments.

The social and economic impacts of the MPB epidemic are many, but research 

on this topic is limited. Such research is necessary to understand the tradeoffs 

associated with management options and to help land managers allocate limited budgets to address public concerns. Additionally, insight into the benefits 

and costs provided by various management options can be communicated to 
50 USDA Forest Service RMRS-P-70. 2014.

stakeholders to enhance the public understanding and support of the unavoidable tradeoffs that must be made.

Research highlighted in this webinar focused on areas where research is available concerning the social and economic effects of the MPB epidemic. These 

efforts focused on (1) opportunities and challenges for utilizing beetle-killed 

trees for woody biomass, (2) impacts of pests on non-market values, and 

(3) public perceptions of forest management following the MPB epidemic. 

Land managers from Bitterroot National Forest in Montana and the ArapahoRoosevelt National Forest in Colorado also provided thoughts and insights about 

socio-economic impacts of the MPB.

Research findings

Research finding #1: The availability of forest industry infrastructure 

greatly affects the cost of tree removal and, therefore, the amount of 

mitigation and hazard removal that can be accomplished.

Forest-industry infrastructure is crucial for dealing with the MPB epidemic. 

States with robust forest-products infrastructure, such as Montana, can finance 

Figure 6.1. Several technological approaches are available for converting biomass into different forms of 

bioenergy (adapted from McKendry 2002).

• The feasibility of selling woody material to offset treatment costs depends on 

hauling distances, transportation costs, market prices, and prices of alternatives 

(e.g., natural gas).

Management

Implications

Woody Biomass

Combustion Gasification Pyrolysis Liquefaction 

/ HTU

Digestion 

Fermentation

Hot 

gases

Low-energy 

gases

Synthesis 

gas

Biochar Bio-oil Organic 

compounds

Heat 

Steam 

Electricity

Combustion 

engines

Turbines

Fuel gas

Methane

Liquid fuels

Chemicals

Methanol

Solid fuels

Soil additives

Industry apps

Liquid fuels

Distillates

Chemicals

Ethanol

Methane

Chemicals

THERMOCHEMICAL CONVERSION PROCESSES

BIOCONVERSION PROCESSES

INTERMEDIATE PRODUCTS

FINAL PRODUCTS
USDA Forest Service RMRS-P-70. 2014. 51

at least some of their management costs by selling some or all of the material. 

Various technologies for converting biomass into energy are available (Fig. 6.1), 

but there are significant challenges involved. When a fully-integrated wood 

processing infrastructure exists, the ability to utilize the timber and biomass 

removed as a result of treatments is greatly enhanced. In places where such 

infrastructure is sparser, like in Colorado, the material is often piled and burned 

in the woods, offsetting none of the costs of treatment (Fig. 6.2).

Additional and new types of wood-processing infrastructure are needed in many 

areas of the country. However, there are significant challenges to developing 

the capacity of private industries to utilize woody biomass. Uncertainty in feedstock availability over time can reduce the willingness of investors to develop 

new facilities or update old facilities. The removal and use of woody biomass is 

economically infeasible in many areas due to high transportation costs to haul 

timber or biomass from infested forests to far-away mills. Transportation costs 

increase with the distance that material must be hauled to the processing facility 

(Jones and others 2013).

The economic feasibility of selling the material also depends on the price that the 

material receives on the market. Market prices for material and the price of diesel 

fuel are volatile factors that make the economics of biomass removal uncertain 

over time (Fig. 6.3). Prices that people are willing to pay for woody material is 

highly influenced by the end use of the material (lumber, posts poles, fuel) and the 

price of alternatives. For example, the price of natural gas and other conventional 

Figure 6.2. Fully integrated wood processing 

infrastructure (top) enhances the ability 

of industry to utilize timber and biomass 

removed from forests. In contrast, the 

absence of an integrated wood processing 

infrastructure (bottom) leaves management 

agencies with fewer or no options for 

offsetting treatment costs. Woody material is 

often left on-site or piled and burned (figure 

by Nate Anderson, USDA Forest Service).

pulpwood

 forest 

residue

sawlogs

mill

residue

lumber

pulp, etc.

heat & 

power

processing

conversion

lumber

landfill

mill

residue

heat & 

power

fossil

fuel

pulpwood

 forest 

residue

sawlogs

boiler / cogen
52 USDA Forest Service RMRS-P-70. 2014.

fuel types will influence the purchase price for biomass: the lower the cost of 

natural gas, the lower the price purchasers are willing to pay for biomass.

Research finding #2: Forest biomass use can replace fossil fuels and reduce 

emissions relative to piling and burning.

Scientists at the Rocky Mountain Research Station compared emissions from 

(1) piling and burning forest residues onsite vs. burning natural gas for energy, 

Figure 6.3. The amount of biomass (BDT = bone dry ton) that is economically feasible to deliver depends on 

biomass prices and diesel fuel costs (modified from Jones and others 2013).

• Piling and burning biomass emits large quantities of carbon dioxide and 

particulate matter without offsetting the use of fossil fuel.

• Where infrastructure is available, utilizing biomass for thermal energy can 

reduce greenhouse gas and particulate matter emissions and offset fossil fuel 

use.

Management

Implications

0

2

4

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8

10

12

14

16

0

50

100

150

200

250

300

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450

$2 $3 $4 $5

Delivered biomass (1000s BDT)

Diesel price per gallon

Biomass $28.60 / BDT

Biomass BDT (1000s) Max avail. volume (1000s BDTs) Net revenue (millions)

0

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6

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0

50

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Diesel price per gallon

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0

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0

50

100

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$2 $3 $4 $5

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Diesel price per gallon

Biomass $57.20 / BDT

0

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$2 $3 $4 $5

Net revenue (millions)

Diesel price per gallon

Biomass $42.90 / BDT
USDA Forest Service RMRS-P-70. 2014. 53

(2) piling and burning forest residues onsite vs. burning #2 distillate oil for energy, and (3) burning forests residues in a boiler for thermal energy (Jones and 

others 2010a,b). They found that burning forest residues (including trees killed 

by the MPB that can no longer be used as saw timber) in a boiler emitted levels 

of carbon dioxide similar to piling and burning woody material. However, total 

emissions are lower for burning biomass in a boiler for thermal heat because it 

replaces the need to burn fossil fuels (Fig. 6.4). In addition, burning biomass in 

a boiler emits far less particulate matter (Fig. 6.5) and methane than piling and 

burning biomass. Emissions were lower for biomass utilization even after accounting for transportation of the material by truck.

These results show that the utilization of biomass (including that produced from 

beetle-killed trees) can produce several benefits, including meeting energy needs 

and reducing greenhouse gas and particulate matter emissions. This may be particularly advantageous in areas where air quality standards restrict burning.

Figure 6.4. Burning 

biomass in a boiler or in 

piles emits similar levels 

of carbon dioxide (lbs 

CO2 / dry ton of woody 

material). However, 

total emissions are 

lower for burning 

biomass in a boiler for 

thermal heat because 

it replaces the need to 

burn fossil fuels (Jones 

and others 2010a,b).

Figure 6.5. Burning 

biomass in a boiler 

emits far less 

particulate matter (lbs 

of PM10 [particulates 

<10 microns in 

diameter] / dry ton of 

woody material) than 

piling and burning 

biomass. This is true 

with or without wet 

scrubbers to remove 

particulates (Jones and 

others 2010a,b).
54 USDA Forest Service RMRS-P-70. 2014.

Research finding #3: The MPB epidemic has substantial impacts on both 

nonmarket and market values.

Economists evaluate the worth of market values based on prices set through 

supply and demand. Real estate, timber products, and forestry equipment are 

examples of market values. Non-market values are different from market values 

because they do not have price tags. Since there is no market for these values, 

it is harder to quantify their economic worth. Examples include scenic beauty, 

some recreation opportunities, and biodiversity. Very few researchers have 

evaluated the impact of the MPB on nonmarket values.

A review paper found 22 studies related to nonmarket valuation and forest 

insect pests, but only 8 of these studies measured the nonmarket values associated with MPB outbreaks (Rosenberger and others 2012). Seven of these studies 

were done in the Intermountain West and one was from the Northwest, and 

all but one were published from 1975 to 1991. The types of values estimated 

included effects on property values, recreation, and total economic value. All of 

these studies indicated there are substantial economic losses associated with 

MPB outbreaks.

Losses in recreation benefits were estimated to be approximately $2 million 

per year (in today’s dollars) on the Targhee National Forest following a MPB 

outbreak (Michalson 1975). A study assessing the effect of beetle-killed trees 

on home prices in Colorado found that sale prices were decreased by $648 for 

every dead tree within 330 feet of a house. The average sale price was $276,000 

and the average number of dead trees was four (Price and others 2010).

Impacts of MPB outbreaks on nonmarket values are an important social and 

economic issue. More research is needed to provide adequate information 

about the tradeoffs associated with management of MPB epidemics. Available 

research clearly demonstrates that the benefits forests provide to people are 

diminished by MPB outbreaks. These losses are not adequately captured by 

analyses of traditional economic markets.

Research finding #4: Citizens in northern Colorado and southern Wyoming 

generally favor the use of beetle-killed trees for wood products, but many 

are skeptical that forest managers are doing enough in response to the 

MPB epidemic.

Researchers at Colorado State University and their collaborators surveyed households in northern Colorado and southern Wyoming from 2011-2012 about their 

perceptions of the MPB epidemic (Czaja and others 2012). About 740 individuals 

• Public support for hazardous tree removal is high (in the region studied).

• Communicating management challenges and feasibility issues to the public is 

important for developing mutual respect.

• Closing roads and posting signs will not discourage some citizens from recreating 

in areas with hazardous trees. Some people are willing to accept a greater 

degree of risk. 

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 55

responded to the survey, representing a broad cross section of citizens in the 

region.

The majority of respondents (92 percent) agreed that land managers should use 

trees killed by the MPB for wood products and biomass. About three-fourths of respondents disagreed that beetle-killed trees should be left in the forest. A majority 

of respondents (96 percent) agreed that people who recreate in forests should 

accept some of the risk associated with falling trees, but about three-fourths of 

respondents agreed that some activities should be restricted or made inaccessible.

Several questions addressed the trust that respondents had in actions taken by 

land management agencies. Only 59 percent of respondents agreed that forest 

managers are doing everything they should in response to the MPB epidemic. 

In contrast, greater trust was put in the knowledge and skills of managers about 

prescribed burns and wildfires. A majority of respondents (82 percent) agreed 

that forest managers know how to effectively conduct prescribed fires, and 87 

percent agreed that forest managers know how to respond to naturally-caused 

wildfires. A lower number of respondents (61 percent) agreed that forest mangers know how to effectively manage smoke resulting from prescribed fires. 

An important caveat is that these responses were collected prior to a fatal and 

destructive prescribed burn that escaped control lines in northern Colorado. This 

study indicates that the citizens are not convinced that managers have a welldefined strategic plan for responding to the epidemic. Greater dialogue between 

managers and the public might increase agency awareness of ecological, social, 

and economic implications of post-epidemic management options while also 

increasing stakeholder support for agency decisions.

Manager perspectives

The public is concerned about the impact of the MPB on recreational 

opportunities and aesthetics.

The personnel from the Bitterroot National Forest and Arapaho-Roosevelt 

National Forest shared their thoughts on the social and economic impacts of the 

MPB epidemic, which are summarized here.

Forest Service units within the footprint of the MPB epidemic have to balance 

concerns for human safety with the demands for beautiful and accessible 

• Managers should be proactive when facing increased risk of disturbance events. 

Reducing hazards associated with MPB outbreaks or wildfire can maintain 

aesthetic beauty and protect infrastructure better than post-disturbance 

mitigation projects.

• Communication among managers can improve decision making by sharing 

lessons learned from previous disturbances.

• Managers and the public should discuss inevitable tradeoffs posed by the 

epidemic and develop a triage strategy for hazardous tree removal. This 

might increase public trust that land management agencies are adequately 

responding to the MPB epidemic.

Management

Implications
56 USDA Forest Service RMRS-P-70. 2014.

recreation facilities. Experiences with the epidemic on the Helena National 

Forest prepared managers of the Bitterroot National Forest for what was coming, allowing them to be proactive rather than reactive. As such, the managers 

of the Bitterroot National Forest were able to remove hazardous trees and 

promote scenic beauty at a popular campground before the MPB epidemic. 

Residual trees at the campground survived the MPB outbreak, and as a result 

there was little concern about the safety of campers after the outbreak (Fig. 6.6).

However, a proactive approach is not always possible or wise. For example, managers on the Arapaho-Roosevelt National Forest thinned trees around popular 

campgrounds, but they had to return several times as more trees succumbed 

to MPB infestations. Re-entry carries additional costs to land management 

agencies. Continual thinning of trees can lead to a lack of privacy and shade in 

campgrounds (Fig. 6.7), causing some people to go elsewhere or participate in 

different types of recreational activities.

The public is often quite familiar with wildfire and prescribed fire and generally 

trusts that the agency knows how to handle these activities (Czaja and others 

2012). They have less trust regarding agency response to the MPB epidemic, 

making communication and education particularly important. Managers, 

stakeholders, and the public should frequently communicate about the future 

of post-epidemic forests. There needs to be better public involvement in discussions about likely impacts of management decisions, priority setting, and 

inevitable tradeoffs posed by the MPB epidemic. Clearly articulated goals can 

guide post-epidemic salvage operations and balance the ecological, social, and 

economic tradeoffs of management decisions.

• As the need for hazardous tree removal declines, is there an adequate supply of 

federal timber to support new and existing forest products infrastructure? Are 

unrealistic expectations being created about the feasibility of wood products 

industries?

• What opportunity costs are associated with management responses to the MPB 

epidemic (e.g., using money from other programs and/or reduced capacity to 

undertake other management activities)? What effect will this have on future 

forests and the benefits they provide to people?

• To what degree are concerns about safety and/or diminishing aesthetic values 

changing forest visitation and use patterns? What effects will this have on forest 

recreation programs, budgets, etc.?

• What will campgrounds impacted by the MPB epidemic look like 5 years from 

now? 10 years from now? Is there a need for artificial structures to provide 

shade and screening?

Remaining

Questions &

Knowledge Gaps
USDA Forest Service RMRS-P-70. 2014. 57

Figure 6.6. Managers on the Bitterroot National Forest removed 

hazardous fuels and were able to protect residual trees and 

aesthetic beauty at a favorite campground during the MPB 

epidemic. The same picnic table is highlighted in both images 

(photos by Erica Strayer, USDA Forest Service).

Figure 6.7. Managers on the Arapaho-Roosevelt National Forest 

removed hazardous trees several times during the MPB epidemic, 

compromising privacy, shade, and aesthetic beauty at a popular 

campground. The same facility is highlighted in the two posttreatment images (photo by Erica Strayer, USDA Forest Service).

Before 

treatment

After

treatment

Before 

treatment

After 1st

treatment

After 2nd

treatment
58 USDA Forest Service RMRS-P-70. 2014.

Literature cited

Clement, J.M. and A.S. Cheng. 2011. Using analyses of public value orientations, 

attitudes and preferences to inform national forest planning in Colorado and 

Wyoming. Applied Geography 31:393-400.

Czaja, M., S. Cottrell, A. Bright, and J. Clement. 2012. Public perceptions of the 

mountain pine beetle in three study areas in Northern Colorado and Southern 

Wyoming. Report to the U.S. Forest Service and Colorado State Forest Service. 

Colorado State University, Fort Collins, CO. 125 pp.

Jones, G., D. Loeffler, E. Butler, W. Chung, and S. Hummel. 2010a. Emissions, 

energy return and economics from utilizing forest residues for thermal energy 

compared to onsite pile burning. Pp 145-153 in Jain, T. B., R.T. Graham, and 

J. Sandquist (eds.). Integrated Management of Carbon Sequestration and 

Biomass Utilization Opportunities in a Changing Climate: Proceedings of the 

2009 National Silviculture Workshop. 15-18 June 2009, Boise, ID. Proceedings 

RMRS-P-61. U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station, Fort Collins, CO. 351 pp.

Jones, G., D. Loeffler, D. Calkin, and W. Chung. 2010b. Forest treatment residues 

for thermal energy compared with disposal by onsite burning: Emissions and 

energy return. Biomass and Bioenergy 34(5):737-746.

Jones, G., D. Loeffler, E. Butler, S. Hummel, and W. Chung. 2013. The financial 

feasibility of delivering forest treatment residues to bioenergy facilities over 

a range of diesel fuel and delivered biomass prices. Biomass and Bioenergy 

48:171-180.

McKendry, P. 2002. Energy production from biomass (part 2): Conversion 

technologies. Bioresource Technology 83:47-54.

Michalson, E.L. 1975. Economic impact of mountain pine beetle on outdoor 

recreation. Southern Journal of Agricultural Economics 7(2):43-50.

Price, J.I., D.W. McCollum, and R.P. Berrens. 2010. Insect infestation and 

residential property values: A hedonic analysis of the mountain pine beetle 

epidemic. Forest Policy and Economics 12(6):415-422.

Rosenberger, R.S., L.A. Bell, P.A. Champ, and E.L. Smith. 2012. Nonmarket 

economic values of forest insect pests: An updated literature review. General 

Technical Report RMRS-GTR-275WWW. U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 46 pp. 

[online] URL: http://www.treesearch.fs.fed.us/pubs/40491.
USDA Forest Service RMRS-P-70. 2014. 59

Meet the chapter presenters and authors

Patty Champ is an economist with the Rocky Mountain 

Research Station in Fort Collins, CO. She has been with the 

station for 18 years. Her broad interest is in understanding 

public preferences related to land management issues. 

She is an expert on nonmarket valuation methods, and she 

conducts research on wildfire risk and homeowners in the 

wildland urban interface. Reach Patty at pchamp@fs.fed.us; 

970-295-5967.

Jessica Clement has conducted human dimensions 

in natural resources research in Colorado, Wyoming, and 

Montana for about twenty years. She currently leads the 

Collaborative Leadership Program for the Ruckelshaus 

Institute at the University of Wyoming. She is trained 

in ecology and social science, with a research focus on 

collaborative natural resource decision-making processes. 

Reach Jessica at jessica.clement@uwyo.edu; 719-641-6680.

Paul E. Cruz is the Forest Recreation Program Manager 

for the Arapaho and Roosevelt National Forests and 

Pawnee National Grassland. Other positions he has held 

with the agency include Forest Travel Rule Implementation 

Team Leader, Acting Recreation Fee and Business Systems 

Program Manager, Acting District Ranger, and District 

Recreation Staff Officer. Prior to his 1990 transfer to the 

Forest Service, Paul was a Soil Conservationist with the 

USDA Soil Conservation Service. Paul can be reached at 

pecruz@fs.fed.us; 970-295-6614.

Mike Czaja is a retired lieutenant colonel in the US Army 

and doctoral candidate at Colorado State University. He is 

interested in wildland fire-related social science research. 

In addition to being a volunteer wildland fire fighter and 

public information officer trainee with the Larimer County 

Sheriff’s Office, he is a fire-prevention volunteer with the 

Canyon Lakes Ranger District of the Arapaho-Roosevelt 

National Forest. Mike can be reached at michael.czaja@

colostate.edu; 970-491-1494.

Krista Gebert is the Regional Economist for the Northern 

Region of the Forest Service. She accepted the position as 

Regional Economist in July of 2010, after nearly 15 years 

as a researcher with the Rocky Mountain Research Station 

in Missoula. Krista has authored or co-authored more 

than 30 topics on topics including timber sale economics; 

rural development; economic dependency on forestrelated industries; and the economics of wildland fire 

management. Reach Krista at kgebert@fs.fed.us; 406-329-

3696.

Greg Jones is a retired Research Forester with the 

Human Dimensions Science Program, Rocky Mountain 

Research Station in Missoula, MT. Greg earned his Ph.D. 

is in Forest Economics from Iowa State University. His 

research included forest fuel treatment economics, biomass 

supply from forest treatments, and utilization of forest 

treatment residues. Greg can be reached at jgjones@fs.fed.

us; 406-329-3396.

Chuck Oliver has been with the Forest Service for 

over 20 years. He is currently the District Ranger on the 

Darby Ranger District of the Bitterroot National Forest 

in Montana. He started his Forest Service career as a 

range conservationist for the Butte Ranger District of the 

Deerlodge National Forest, and he was previously the 

District Ranger on the Parks Ranger District of the Medicine 

Bow/Routt National Forest. Reach Chuck at coliver01@

fs.fed.us; 406-821-3913.
60 USDA Forest Service RMRS-P-70. 2014.
USDA Forest Service RMRS-P-70. 2014. 61

Chapter 7—Small bugs with big impacts: Ecosystem and 

watershed-level responses to the MPB epidemic

Authors: Rob Hubbard, Kelly Elder, Chuck Rhoades, Polly Hays, and Bruce Sims

Presenters: Rob Hubbard, Kelly Elder, Chuck Rhoades, Polly Hays, and Bruce Sims

Introduction

Mountain pine beetle (MPB) outbreaks have the potential for prolonged 

impacts on the delivery of clean water from infested subalpine watersheds throughout the West. Sixty-five percent of the West’s water 

supply originates on forested land (Brown and others 2008), much of which has 

been affected by an unprecedented MPB epidemic over the past decade. Some 

lodgepole pine stands in Colorado have lost more than 70 percent of their basal 

area following the MPB epidemic (Collins and others 2012). The death of pine 

trees leads to increased availability of light, water, and nutrients for residual 

overstory trees and understory vegetation; it can also result in increased water 

and nutrient runoff.

The MPB epidemic may have a large influence on the energy and water balance 

of subalpine ecosystems. Water balance in the subalpine zone is modeled as the 

volume of water stored along with a series of water inputs and outputs from the 

system. The storage component includes ground water, soil moisture and snow 

pack. Inputs consist of precipitation in the form of rain and snow, and outputs 

include sublimation from the snowpack surface and from snow intercepted 

by tree canopies, evaporation from snow-covered and snow-free surfaces, 

and transpiration from trees and other vegetation during the growing season. 

Intercepted snow sublimates at a faster rate than snow on the ground due to its 

greater surface area and exposure to incoming solar radiation and heat transfer 

from the air. Water that is not lost to sublimation, evaporation, or transpiration 

is available for stream flow (Fig. 7.1).

Energy and water balances change throughout the year in subalpine forests. 

During winter, the net energy balance is negative, allowing snow to accumulate 

through the cold season. The energy balance becomes positive during spring, 

and this excess energy is used to warm and subsequently melt snowpack. The 

soil moisture deficit from the previous growing season is replenished as snowmelt moves into the soil. Ground water levels rise, and eventually stream flow 

increases relative to base flow levels during the winter. Trees also begin to transpire as temperatures warm, transferring soil moisture to the atmosphere.

Landscape-scale MPB epidemics have the potential to cause large changes in 

water balance in these subalpine watersheds. Snow is the dominant precipitation input in the subalpine zone where the MPB is most active, and snowmelt 

accounts for the vast majority of water available for runoff, agricultural, and 

municipal uses. After logging operations, decreased snow interception by tree 
62 USDA Forest Service RMRS-P-70. 2014.

canopies leads to increased snowpack accumulation (Woods and others 2004; 

Troendle and King 1985).

Similarly, the magnitude and timing of post-beetle snowmelt will be affected by 

the changes in the tree canopy, even though the forest overstory will deteriorate 

more slowly following a beetle attack than following tree harvesting. The net 

effect of the changing snowpack accumulation and water and nutrient use in 

beetle-killed forests varies depending on environmental conditions, tree species 

composition, the density of the forest understory, and management decisions. 

At the same time, these impacts are occurring against the backdrop of climate 

change, which is already impacting seasonal stream flows. Rood and others 

(2008) compared hydrographs from the early 1900s and early 2000s, and they 

found that many rivers across the West are experiencing higher winter flows, 

earlier spring run-off and peak flows, and reduced flows in the summer and 

early autumn. We have yet to see how these alterations might interact with 

watershed-scale impacts of the MPB epidemic.

In this webinar, we presented research on MPB-induced changes in energy and 

water balances, tree physiology, and nutrient cycling. These processes influence 

stream flow and nutrient and sediment export from affected watersheds.

Research findings

Research finding #1: Blue stain fungi associated with the beetles are 

primarily responsible for tree deaths during MPB outbreaks.

MPBs disrupt two basic life-sustaining processes in trees they infest. Adult 

beetles consume phloem tissue when building egg galleries and developing larvae consume phloem for food until maturity. Phloem feeding by adult and larval 

beetles contributes to some amount of phloem girdling, disrupting the transport 

of carbohydrates from the canopy to other tissues within the tree.

Figure 7.1. The water balance of an ecosystem 

is conceptualized as faucets, buckets, straws, 

and leaks. The faucet represents inputs 

of water from precipitation; the buckets 

represent pools of water in the ecosystem 

(i.e., snowpack, soil moisture, and ground 

water). Water moves out of the system 

through sublimation, evaporation, and 

transpiration (represented as a straw), and it 

leaves the system as water yield and runoff 

(represented as a leak in the bucket) (figure 

by Kelly Elder, USDA Forest Service).

Precipitation 

(rain or snow)

Snowpack 

Soil moisture

Ground water

Sublimation

Transpiration

Evaporation

“Leaks” =

water yield and runoff
USDA Forest Service RMRS-P-70. 2014. 63

MPBs also carry a diversity of pathogenic spores from several genera of fungi 

(Yamaoka and others 1995; Kim and others 2008). Fungal spores carried into 

trees by MPBs germinate and spread fungal hyphae into tree tissue responsible 

for conducting water (i.e., xylem in the sapwood). These fungi essentially block 

water transport from the soil to the canopy (Ballard and others 1984).

Studies at the Fraser Experimental Forest suggest that fungal infection of the 

xylem tissue is the primary cause of tree mortality. Fungal infections cause a 

rapid decrease in tree transpiration following a successful MPB attack. Tree 

water use can slow measurably ten days following a MPB attack, decline to 50 

percent by the end of the summer, and essentially reach zero by the beginning 

of the next growing season (Fig. 7.2). Mechanically girdling trees without fungal 

infection resulted in slower transpiration rates during the first growing season, 

but transpiration rates of these trees were similar to control trees during the 

following summer. This experiment demonstrates that fungal infections, not 

phloem consumption by beetles, are primarily responsible for tree deaths during 

MPB outbreaks (Hubbard and others 2013).

Research finding #2: Tree mortality caused by the MPB epidemic 

substantially alters energy and water balances in subalpine forests.

Forest cover is a critical driver of water balance in subalpine environments. MPB 

outbreaks cause changes to water and energy balance as trees transition from 

live canopies to dead foliage (i.e., red stage), and finally to losing all of their 

needles (i.e., gray stage).

Figure 7.2. Relative rates of transpiration for beetleattacked trees compared to control trees before and 

following MPB infestation (A), and mean sap flux density 

in the growing season following MPB infestation for 

beetle-attacked, girdled, and control trees (B). Error bars 

represent the variation between trees (figure modified 

from Hubbard and others 2013).

July 9

July 19July 29

Aug 8

Aug 18Aug 28

Sept 07

Relative Transpiration

0.4

0.6

0.8

1.0

1.2

1.4

Average Transpiration (cm

April 09 May 14 June 18 July 23 Aug 27 Oct 1

3 cm-2 h-1) 0

2

4

6

8

(A) 2006

(B) 2007

Relative transpiration (%)

8

6

4

2

0

Mean weekly sap flux density 

(cm3 / cm2 / hr) 1.4

1.2

1.0

0.8

0.6

0.4

 July July July Aug Aug Aug Sept 

 9 19 29 8 18 28 7

 Apr May June July Aug Oct 

 9 14 18 23 27 1 

Control

MPB

Girdled
64 USDA Forest Service RMRS-P-70. 2014.

Transpiration declines between the green and red stages. The introduction of 

blue stain fungi by MPBs causes pine needles to discolor and turn red as transpiration declines. Transpiration ceases altogether by the beginning of the first 

post-infection growing season (Hubbard and others 2013). Water previously 

removed by transpiration is then available for soil recharge, residual vegetation 

transpiration and/or stream flow.

Changes in watershed-level transpiration rates depend on the amount of 

MPB-induced tree mortality (which in turn depends on the original species composition and management history). Total basal area was reduced by 25 percent 

in managed mixed-species subalpine watersheds at Fraser Experimental Forest, 

whereas basal area losses averaged 40 percent in unmanaged stands (Fig. 7.3). 

These changes in basal area resulted in proportional changes in overstory transpiration rates. Transpiration in two managed watersheds was reduced by 20 

and 29 percent, but transpiration in two unmanaged watersheds was reduced by 

41 and 45 percent (Rob Hubbard, USDA Forest Service, unpublished data).

Interception does not change significantly between the green and red stages. 

Dead needles may intercept as much snow as living needles. However, interception begins to decline as trees transition into the gray stage, shedding their 

Figure 7.3. MPB-induced mortality 

of lodgepole pine trees (hatched 

bars) in unmanaged and 

managed watersheds at the 

Fraser Experimental Forest. Error 

bars represent the variation 

between subplots plots in each 

watershed (Chuck Rhoades, Rob 

Hubbard, and Kelly Elder, USDA 

Forest Service, unpublished 

data).

• Soil water availability and stream flow can increase during the red stage as 

transpiration of dead and dying trees declines. 

• Greater increases in soil water availability and stream flow are possible during 

the gray stage as less snow is intercepted by needle-less tree canopies.

• Removal of hazard trees can decrease canopy interception, thereby enhancing 

snowpack accumulation in forests impacted by the MPB. However, removing 

large groups of trees can decrease snow accumulation due to wind scour.

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 65

needles over a period of 1 to 5 years. Once all needles have been shed from the 

tree, interception is significantly lower, but it will not be zero until a tree topples 

to the ground anywhere from 1 to 15 years following MPB attack (Mitchell and 

Preisler 1998).

Less interception by tree canopies can translate into greater snowpack accumulation 

(Woods and others 2004). Preliminary results from the Fraser Experimental Forest 

suggest that snow and rain throughfall increase when a larger portion of the overstory is killed by the MPB. Snow accumulation (i.e., depth, density, and water equivalent) 

are significantly higher in gray-stage forests that experience harvesting relative to 

uncut stands (Fig. 7.4). However, several harvested stands had lower snow depths. 

This is potentially from high wind scour due to plot location and/or the large size 

of the harvest units. Differences in silvicultural treatments could have also affected 

snowpack accumulation, with greater accumulation resulting from even thinning 

versus group-retention thinning (Woods and others 2004).

Research finding #3: Changes in the water balance of subalpine forests 

are likely different after tree harvesting than after mortality from the MPB 

epidemic.

Researchers and water managers have experimented with tree removal to increase 

stream flow for more than a hundred years. For example, researchers removed 

50 percent of the forested basal area from the Fool Creek watershed in the Fraser 

Experimental Forest and observed a 40 percent increase in stream flow relative to an 

untreated watershed (Troendle and King, 1985). Over a 50-year period following basal 

area reduction, the average increase in stream flow was 29 percent (Kelly Elder and 

Laurie Porth, USDA Forest Service, unpublished data).

Figure 7.4. Snow depth for transects located 

in uncut versus harvested MPB-affected 

lodgepole stands. Study plots were located 

on the Fraser Experimental Forest, Colorado 

State Forest, Routt National Forest, and 

Medicine Bow National Forest in Colorado. 

The mean differences in snow depth are 

similar to differences observed in clear 

cuts versus unharvested areas impacted by 

the MPB (Kelly Elder, USDA Forest Service, 

unpublished data).
66 USDA Forest Service RMRS-P-70. 2014.

Changes in peak flow and overall runoff in the Fool Creek watershed were driven 

by reduced losses from interception and transpiration, as well as increased snow 

deposition into harvested strips. A recent analysis of yearly stream flows from 

Fool Creek estimates that hydrologic recovery would have occurred approximately 60 years following harvest had no further disturbance altered the system 

(Kelly Elder and Laurie Porth, USDA Forest Service, unpublished data).

It is not known if these studies are appropriate analogs for the impact of tree 

mortality from the MPB and subsequent tree harvesting. Studies that have 

examined impacts of MPB outbreaks on stream flow are relatively rare. Stream 

flows from infested watersheds will likely have a very different response over 

time due to differences in the energy and water balance of harvested versus 

beetle-killed forests.

Increases in stream flow are often lower following beetle-induced tree mortality 

than after tree harvesting. Between 1939 and 1946 a large spruce beetle outbreak killed approximately 20 percent of the basal area within the White River 

watershed in northwestern Colorado. During the 25-year period after the spruce 

beetle infestation, the average increase in water yield was 15 percent, and the 

largest increase occurred 15 years after the outbreak (Love 1955; Bethlahmy 

1974). During the current MPB epidemic, stream flow was not different between 

a watershed infested by the MPB in 2003 and one not infested until 2008 

(Fig. 7.5). These watersheds were decent analogs of each other, with a strong 

correlation in streamflow patterns prior to the MPB epidemic (Kelly Elder and 

Laurie Porth, USDA Forest Service, unpublished data).

Paired watershed studies are of little use in detecting long-term changes in 

stream flow induced by the MPB epidemic. This is because most basins with 

lodgepole pine across the Rocky Mountain West have been significantly impacted by MPBs. Instead, researchers are detecting changes in downstream flows by 

comparing annual precipitation patterns and discharge from beetle-impacted 

basins.

Why might the magnitude of water yield increase be lower following beetleinducted tree mortality than after tree harvesting? Different rates of tree 

removal and different amounts of remaining live vegetation are primary factors 

explaining this pattern.

• Increases in water yields following the MPB epidemic are less substantial than 

increases resulting from clear-cutting operations. This is due to a more gradual 

decline in transpiration and interception rates and the greater abundance of 

live, residual vegetation in MPB affected forests.

• Advance regeneration and newly established vegetation utilize much of the soil 

water made available after the death of overstory trees, dampening increases in 

stream flow after the MPB epidemic.

• Retaining slash in post-epidemic forests (e.g., lop and scatter) can increase snow 

accumulation by reducing wind scour. This potentially leads to greater water 

yields during the spring melt.

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 67

Figure 7.6. Changes in water loss in 

MPB-impacted mature forests 

(A) versus clear cut mature 

forests (B) (figure by Kelly Elder, 

USDA Forest Service).

Figure 7.5. Mean daily flows from 

unaffected North Brush Creek 

watershed in southern Wyoming 

versus MPB-affected East 

St. Louis basin on the Fraser 

Experimental Forest, Colorado. 

Black circles represent pre-beetle 

altered flows and other icons 

represent post-beetle impacted 

flows. The solid regression line 

show the pre-beetle fit between 

the basin flows (data prior to 

2003) and the dashed line show 

the 95 percent confidence 

interval. This data suggests 

that as of 2007, flows were still 

behaving as expected from an 

unaltered hydrologic regime 

(Kelly Elder and Laurie Porth, 

USDA Forest Service, unpublished 

data). 

pre-outbreak observations

trendline

95% confidence interval

2004 2005

2006 2007

Mean daily flows (ft3 / sec) for North Brush Creek

Mean daily flows (ft3 / sec) for 

East St. Louis Creek

3,000

2,000

1,000

0

0 10,000 20,000 30,000

 Pre-beetle Beetle attack Red phase Grey phase Treefall

tttttttt →

New forest Mature forest

Overstory interception Understory interception 

Overstory transpiration Understory transpiration

MPB outbreak

wwww

ww llllllll

(A)

 Pre-cut

tttttttt →

Mature forest

wwww

ww llllllll

Clear cut

Overstory interception Understory interception 

Overstory transpiration Understory transpiration

(B)
68 USDA Forest Service RMRS-P-70. 2014.

Hydrologic recovery is generally slower following harvesting, resulting in a 

greater and more prolonged increase in stream flow (Fig. 7.6). Harvesting results 

in immediate removal of trees, resulting in immediate reductions in water losses 

from overstory interception and transpiration. In contrast, trees killed by MPBs 

shed their canopies slowly and remain part of the ecosystem for many decades, 

resulting in slower declines in interception and transpiration.

The amount of remaining live, vegetation also differs between a harvested and 

beetle-impacted watershed. MPBs only attack mature lodgepole pine trees in 

subalpine forests, leaving other overstory species and understory vegetation 

unaffected. This residual vegetation can quickly respond to increased water 

availability, reducing the amount of water contributing to stream flow. In contrast, harvest operations can remove all of the overstory trees and leave behind 

a much smaller amount of residual vegetation., However, harvesting can also 

increase surface roughness and lead to greater snow accumulation, especially 

when slash is left on-site.

Research finding #4: The MPB epidemic has had little effect on nitrogen 

losses from impacted watersheds.

Wildfire and logging often result in elevated nitrogen in stream water caused by 

changes in nutrient demand and nutrient cycling. The biogeochemical consequences of insect outbreaks are more uncertain. Overstory mortality resulting 

from MPB outbreaks results in lower stand-level demands for nutrients and 

waters. Several studies have similarly shown that soil resources increase under 

dead and dying trees. Clow and others (2011) observed greater soil moisture 

and nitrogen availability under recently-attacked and gray-stage trees in Grand 

County, CO (Fig. 7.7). This increase was potentially due to lower plant uptake, 

slower soil nitrogen turnover, and increased litter inputs.

Greater instantaneous soil nitrogen is apparent under beetle-killed trees, 

but there is little evidence that much of this nitrogen enters stream water. At 

Fraser Experimental Forest, nitrogen export in stream water following the MPB 

epidemic was less than 10 percent of observed seasonal variation (Fig. 7.8), 

and concentrations are well below EPA thresholds for water quality (120 parts 

per billion [ppb] for total nitrogen and 14 ppb for nitrate). Other studies across 

Colorado show similarly low nitrogen export from watersheds affected by the 

MPB epidemic (Rhoades and others 2013).

Why are stream nitrogen responses to the MPB epidemic so small? One reason might be increased nitrogen uptake by residual, live vegetation: at Fraser 

Experimental Forest, average foliage nitrogen content has increased from 0.8 

to 1.3 percent in live pine trees located near beetle-killed trees (Hubbard and 

• The MPB epidemic has marginally increased stream nitrate concentrations, but 

the changes do not pose threats to water quality.

• Protecting tree regeneration and enhancing establishment of new vegetation 

can help mitigate nitrogen losses from forest soils to streams.

Management

Implications
USDA Forest Service RMRS-P-70. 2014. 69

Figure 7.7. Means and standard deviations of soil (a) moisture, (b) available nitrogen, (c) extractable ammonium 

(NH4+), and (d) extractable nitrate (NO3-) in soils collected under live, red-stage, and gray-stage trees. Different 

letters indicate that the distributions were significantly different at p < 0.1 (figure from Clow and others 2011).

Figure 7.8. Nitrate (NO3

-) concentrations in East St. Louis Creek on the Fraser Experimental Forest, CO, before extensive MPB 

kill of trees and during years of beetle kill (shaded area). Annual variation in nitrate concentrations dwarfs potential impacts 

of the MPB epidemic on water quality (figure from Rhodes and others 2013).

others 2013). More than 25 percent of trees sampled from four watersheds 

at Fraser showed increased growth in response to beetle-induced mortality of 

nearby trees. Likewise, seedlings are colonizing beetle-impacted areas across 

northern Colorado, and advance regeneration trees are growing faster than 

previous years in response to increased resource availability (Collins and others 

2011).
70 USDA Forest Service RMRS-P-70. 2014.

Literature cited

Ballard, R.G., M.A. Walsh, and W.E. Cole. 1984. The penetration and growth 

of blue-stain fungi in the sapwood of lodgepole pine attacked by mountain 

pine-beetle. Canadian Journal of Botany-Revue Canadienne De Botanique 

62:1724-1729.

Bethlahmy, N. 1974. More streamflow after a bark beetle epidemic. Journal of 

Hydrology 23:185-189.

Brown, T.C., M.T. Hobbins, and J.A. Ramirez. 2008. Spatial distribution of water 

supply in the coterminous United States. Journal of the American Water 

Resources Association 44:1474-1487.

Clow, D.W., C. Rhoades, J. Briggs, M. Caldwell, and W.M. Lewis. 2011. Responses 

of soil and water chemistry to mountain pine beetle induced tree mortality in 

Grand County, Colorado, USA. Applied Geochemistry 26:S174-S178.

Collins, B.J., C.C. Rhoades, R.M. Hubbard, and M.A. Battaglia. 2011. Tree 

regeneration and future stand development after bark beetle infestation 

and harvesting in Colorado lodgepole pine stands. Forest Ecology and 

Management 261:2168-2175.

Collins, B.J., C.C. Rhoades, M.A. Battaglia, and R.M. Hubbard. 2012. Salvage 

logging reduces fire risks after bark beetle outbreaks in lodgepole pine 

forests. Forest Ecology and Management 284:260-268.

Hubbard, R.M., C.C. Rhoades, K. Elder, and J. Negron. 2013. Changes in 

transpiration and foliage growth in lodgepole pine trees following mountain 

pine beetle attack and mechanical girdling. Forest Ecology and Management 

289:312-317.

Kim, J.J., A. Plattner, Y.W. Lim, and C. Breuil. 2008. Comparison of two methods 

to assess the virulence of the mountain pine beetle associate, Grosmannia 

clavigera, to Pinus contorta. Scandanavian Journal of Forest Research 

23:98-104.

Love, L.D. 1955. The effect on stream flow of the killing of spruce and pine by the 

Engelmann spruce beetle. Transactions of the American Geophysical Union 

36:113-118.

• How will the magnitude and timing of changes in water quality and quantity 

vary over time as forests recover from the MPB epidemic? Are these responses 

similar or different for watersheds in other parts of the beetle-killed landscape? 

• To what degree does beetle-induced tree mortality change snow accumulation 

and retention over time? 

• How will water and nutrient uptake by residual live vegetation change as forests 

recover from the MPB epidemic?

• What impact will future disturbances (e.g., forests insects and diseases, 

wildfires, and management activities) have on watershed processes in areas 

impacted by the current MPB epidemic? 

• What are the implications of salvage harvesting in riparian areas for wildlife 

habitat, soil water holding capacity, stream temperatures, etc.?

Remaining 

Questions & 

Knowledge Gaps
USDA Forest Service RMRS-P-70. 2014. 71

Mitchell, R.G. and H.K. Preisler. 1998. Fall rate of lodgepole pine killed by the 

mountain pine beetle in central Oregon. Western Journal of Applied Forestry 

13:23-26.

Rhoades, C.C., J.H. McCutchan, L.A. Cooper, D. Clow, T.M. Detmer, J.S. Briggs, 

J.D. Stednick, T.T. Veblen, R.M. Ertz, G.E. Likens, and W.M. Lewis. 2013. 

Biogeochemistry of beetle-killed forests: Explaining a weak nitrate response. 

Proceedings of the National Academy of Sciences of the United States of 

America 110:1756-1760.

Rood, S.B., J. Pan, K.M. Gill, C.G. Franks, G.M. Samuelson, and A. Shepherd. 

2008. Declining summer flows of Rocky Mountain rivers: Changing seasonal 

hydrology and probable impacts on floodplain forests. Journal of Hydrology 

349:397-410.

Troendle, C. and R.M. King. 1985. The effect of timber harvest on the Fool Creek 

watershed, 30 years later. Water Resources Research 21:1915-1922.

Woods, S.W., W. McCaughey, R. Ahl, and J. Sappington. 2004. Effects of 

alternative silvicultural treatments on snow accumulation in lodgepole 

pine stands, Montana, U.S.A. Pp 65-73 in Proceedings of the 72nd Annual 

Western Snow Conference, 19-21 Apr. 2004, Richmond, B.C. Western Snow 

Conference, Brush Prairie, WA.

Yamaoka, Y., Y. Hiratsuka, and P.J. Maruyama. 1995. The ability of Ophiostoma 

clavigerum to kill mature lodgepole pine trees. European Journal of Forest 

Pathology 25:401-404.
72 USDA Forest Service RMRS-P-70. 2014.

Meet the chapter presenters and authors

Kelly Elder has worked as a Research Hydrologist with 

the Rocky Mountain Research Station since 2000. He 

received his Ph.D. in physical geography and hydrology 

from the University of California, Santa Barbara. Kelly’s 

research examines consequences of MPB outbreaks and 

management on watershed processes, with a particular 

focus on water balance of subalpine forest systems. He can 

be reached at kelder@fs.fed.us; 970-498-1233.

Polly Hays is the Water Program Manager for the Rocky 

Mountain Region of the Forest Service, a position she has 

held since 2000. She has regional-level responsibilities for 

watershed management and restoration, water quality, and 

water rights. Polly earned her M.S. in Geosciences from 

the University of Arizona. Reach Polly at pehays@fs.fed.us; 

303-275-5096.

Rob Hubbard has worked as a Research Ecologist with 

the Rocky Mountain Research Station since 2005. He 

worked as a Research Ecologist for the Coweeta Hydrologic 

Lab in North Carolina after graduating with his Ph.D. in 

Forest Ecology from Colorado State University. Rob’s 

research explores how forests respond to disturbances and 

the role that plants play in regulating hydrologic processes. 

Reach Rob at rhubbard@fs.fed.us; 970-498-1260.

Chuck Rhoades is a watershed biogeochemist and 

has been with the Rocky Mountain Research Station 

since 2003. He earned his Ph.D. in forest biogeochemistry 

and soil ecology from the University of Georgia in 1998. 

Chuck’s research interests focus on forest biogeochemical 

processes that regulate the delivery of clean water and 

sustain productive soils and forests. He can be reached at 

crhoades@fs.fed.us; 970-498-1250.

Bruce Sims is the Regional Hydrologist for the Northern 

Region of the Forest Service, a position he has held since 

2000. Bruce has done research on the effects of prescribed 

fire on water quality, and he co-authored a general 

technical report looking at the effectiveness of post-fire 

hillslope treatments. He received his M.Ed. in Geography 

and M.S. in Watershed Management from the University 

of Arizona. Bruce can be reached at bsims@fs.fed.us; 406-

329-3447.
USDA Forest Service RMRS-P-70. 2014. 73

Chapter 8—Moving forward: Responding to and mitigating 

effects of the MPB epidemic

Authors: Claudia Regan, Barry Bollenbacher, Rob Gump, and Mike Hillis

Presenters: Claudia Regan, Barry Bollenbacher, Rob Gump, and Mike Hillis

Introduction

T

he final webinar in the Future Forest Webinar Series provided an example 

of how managers utilized available science to address questions about 

post-epidemic forest conditions. Assessments of current conditions and 

projected trends, and how these compare with historical patterns, provide 

important information for land management planning. Large-scale disturbance 

events, such as the MPB epidemic, can change future vegetation conditions, 

disturbances and disturbance interactions, and habitat for wildlife species. This 

case study from the Beaverhead-Deerlodge National Forest illustrates the value 

of rapid assessments for conservation planning, and it provides a template for 

future science-management collaboration.

Lessons learned

Lesson learned #1: The involvement of diverse resource specialists 

can improve the focus and outcomes of rapid assessments and create 

opportunities for science-management partnerships.

The Beaverhead-Deerlodge National Forest experienced substantial tree mortality from the MPB epidemic, with approximately 50 percent of the forested area 

infested by 2009. At the same time, this forest is experiencing an outbreak of 

western spruce budworm. This widespread tree mortality created a management need for information on potential impacts of the MPB and alternative 

management responses.

A diverse team of experts convened to address these goals and information 

needs. Resource managers and specialists with the Beaverhead-Deerlodge 

National Forest contracted employees with TEAMS (Talent, Expertise, Agility, 

Mobility, and Simplicity) Enterprise to recommend silvicultural prescriptions and identify treatment areas. Managers and specialists with the 

Beaverhead-Deerlodge National Forest and Northern Region then formed an 

assessment team with the Ecosystem Research Group (ERG)7 to build on these 

recommendations.

The rapid assessment was comprehensive, but also focused, due to the unique 

perspectives of different resource specialists regarding important ecosystem 

components. The team developed the following goals for the assessment:

7 ERG is a government contractor specializing in natural resource inventory and assessment.
74 USDA Forest Service RMRS-P-70. 2014.

1. Evaluate long-term trajectories of vegetation conditions across the National 

Forest and broader landscape, with a focus on distributions of forest size 

classes, crown closure, and cover types.

2. Determine the scale and intensity of treatment impacts on wildlife habitats 

and species viability, especially for the northern goshawk, flammulated owl, 

black-backed woodpecker, fisher, elk, pileated woodpecker, Canada lynx, 

wolverine, and grizzly bear.

3. Assess the potential severity of future disturbances (especially wildfire) across 

the landscape.

4. Identify projects that might move the forested landscape towards desired 

future conditions as defined by the Forest Plan.

Due to the Forest’s urgent need for information about the MPB epidemic, 

interactions with non-governmental organizations were limited. Future assessments could greatly benefit from greater involvement with diverse stakeholders 

groups (e.g., The Nature Conservancy, The Wilderness Society, The Defenders 

of Wildlife, The Wildlife Society, and commodity interest groups) to effectively 

incorporate their perspectives and encourage collaborative learning among all 

parties.

Lesson learned #2: Simulation models are useful tools for comparing 

impacts of treatment options and exploring future scenarios, especially 

when models are tailored to local conditions.

Simulation models help resource managers explore future conditions under different management and no-management scenarios. The assessment team for 

the Beaverhead-Deerlodge National Forest used SIMPPLLE (SIMulating Patterns 

and Processes at Landscape scaLEs) for this purpose. SIMPPLE is a landscape 

simulation model that produces spatially-explicit projections of how forest 

stands and forested landscapes might change over time (Chew and others 2012). 

The model accounts for variability in topography, wind direction, fuels, and conditions in adjacent stands, as well as projected future climate and disturbances. 

The project only took a couple of months to complete because the SIMPPLE 

model was already parameterized for the Northern Region as part of the Forest 

Plan Revision process.

The model employs “logic pathways” describing trajectories of vegetation 

change. The assessment team tailored these logic pathways to local conditions 

using the Northern Region’s vegetation map (VMAP), regional LANDFIRE 

data, and aerial detection surveys of MPB activity. These datasets were compared to more accurate information from Forest Inventory and Analysis (FIA) 

plots where possible (Ecosystem Research Group 2010). In addition, fire and fuel 

staff with the National Forest worked with fire modeling specialists to improve 

the accuracy of LANDFIRE data for the area (Fig. 8.1).

The team used SIMPPLE to assess the quantity and spatial arrangement of 

wildlife habitat through the use of “queries.” Queries function as habitat models, 

providing descriptions of important habitat characteristics for different species. The validity of model output depends on accurate identification of habitat 
USDA Forest Service RMRS-P-70. 2014. 75

characteristics most constraining to specific wildlife species. Therefore, the assessment team created queries for each species based on an extensive literature 

review and communication with Forest Service wildlife biologists. For example, 

the assessment team focused on stands with large trees (dbh ≥ 10 inches) 

and dense understories when assessing suitable nesting habitat for northern 

goshawks.

The rapid assessment and simulation modeling provided important insight to resource managers and specialists with the Beaverhead-Deerlodge National Forest 

and the Northern Region. The results have already informed decision making 

and changed plans for project implementation. Forest managers were especially 

grateful to the assessment team for detailed information on cumulative effects 

to wildlife habitat. Species viability is evaluated at the forest-level per Forest 

Planning Regulations, so the finer-resolution information from this assessment 

is essential for planning at the project level. Managers with the National Forest 

have already incorporated the assessment findings into NEPA analyses and used 

them for forest-wide consultation with the U.S. Fish & Wildlife Service on delineation management of grizzly bear habitat.

Lesson learned #3: Assessments should consider the effects of natural 

disturbances and management actions at different spatial scales and over 

different timeframes.

Model output from SIMMPLE was used to compare the potential impacts of 

management strategies at different spatial scales, information that is important 

for conservation biological diversity (Haufler 1999). The rapid assessment was 

conducted for three spatial scales: the landscape in and around the BeaverheadDeerlodge National Forest (8.3 million acres), the forested portion of the 

Beaverhead-Deerlodge National Forest (2.6 million acres), and twelve smaller 

landscapes within the National Forests (20 to 573 thousand acres) (Fig. 8.2).

Figure 8.1. Managers and researchers used local data and expertise to refine LANDFIRE data for the 

Beaverhead-Deerlodge rapid assessment. FlamMap predictions of fire spread and behavior across 

a 60,000 acre treatment unit were substantially different when the team used the refined dataset 

(a) instead of the raw LANDFIRE data (b).

Active crown fire

Passive crown fire

Surface fire

Predicted fire behavior
76 USDA Forest Service RMRS-P-70. 2014.

Results from simulation modeling for the Beaverhead-Deerlodge National Forest 

demonstrate that the effects of natural disturbances and silvicultural treatments 

varied with scale (Ecosystem Research Group 2010):

• Treatments substantially altered vegetation characteristics, such as forest 

structural stage and canopy cover, within treated stands. However, the 

percentage of the landscape occupied by different cover types was similar 

among treatments and no-treatment scenarios at the end of the simulation 

period (Fig. 8.3).

• Simulated treatments affected fire occurrence at both the treatment and 

landscape scale. Some simulated treatments resulted in 50 percent fewer 

acres burned compared to the no-treatment scenario, and all treatments 

combined resulted in 8 percent fewer acres burned across the landscape.

• The availability of wildlife habitat across the entire landscape remained 

relatively unchanged during the 50-year simulation period, regardless of 

the treatment or no-treatment scenario. Exact locations of potential habitat 

for the nine focal species varied among treatment scenarios, resulting in 

observable differences within individual treatment units (Fig. 8.4).

Figure 8.2. Map of 11 landscape areas 

for the Beaverhead-Deerlodge 

National Forest’s rapid assessment 

(National Forest System land in 

green).
USDA Forest Service RMRS-P-70. 2014. 77

Figure 8.3. Modeled canopy cover for the year 2060 on the Gravelly and Madison landscape areas of the Beaverhead-Deerlodge 

National Forest. No treatment (A) and treatment (B) scenarios resulted in fairly similar predictions of canopy cover at the spatial 

scale of landscape areas (adapted from Ecosystem Research Group 2010).

Figure 8.4. Potential habitat for 

northern goshawk in and around 

the Beaverhead-Deerlodge 

National Forest covered similar 

acreage in 2010 and 2020 under 

the treatment scenario (about 

760,000 acres). However, the 

location of potential habitat 

shifted over time, with some 

landscape units gaining potential 

habitat and others losing potential 

habitat (adapted from Ecosystem 

Research Group 2010).

0	
  

50,000	
  

100,000	
  

150,000	
  

200,000	
  

Big	
  Hole	
  

Boulder	
  River	
  

Clark	
  Fork-­‐

Flints	
  

Elkhorn	
  

Gravelly	
  

Jefferson	
  

River	
  

Lima	
  Tendoy	
  

Madison	
  

Pioneer	
  

Tobacco	
  

Roots	
  

Upper	
  Clark	
  

Fork	
  

Upper	
  Rock	
  

Creek	
  

Poten&al	
  habitat	
  for	
  northern	
  goshawk	
  

(acres)	
  

2010	
   2020	
  

Dillon

Ennis

Miles

0 5 10 20

N

15-39% cover

40-69% cover

70-100% cover

N.F. boundary

Roads

County lines

Without treatment (A)

Dillon

Ennis

Miles

0 5 10 20

N

With treatment (B)
78 USDA Forest Service RMRS-P-70. 2014.

The assessment team was initially surprised by the minor impact that treatment 

scenarios had on vegetation, disturbances, and wildlife habitat. Upon further 

consideration, they realized that the limited extent of proposed treatments 

likely resulted in these predicted outcomes. Simulated treatments only covered 

350,000 acres (13 percent) of the forested portion of the Beaverhead-Deerlodge 

National Forest. Budgetary constraints, feasibility considerations, and other 

management objectives limit the acres that can reasonably be treated.

Lesson learned #4: Managers and researchers need to consider model 

assumptions and limitations when interpreting results.8

The rapid assessment for the Beaverhead-Deerlodge National Forest highlights 

the utility of simulation modeling for assessing potential futures of disturbance-prone forests. This case study also points to the value of multi-scaled 

assessments for informing resource management planning and management 

actions. Another key aspect of the Beaverhead-Deerlodge National Forest 

assessment is the team’s explicit consideration of model assumptions and 

limitations.

Complexity in ecosystem processes and disturbance interactions, as well as 

uncertain future conditions, render it impossible to predict treatment effects 

and future vegetation patterns with certainty. This reality was discussed and 

acknowledged by the assessment team for the Beaverhead-Deerlodge National 

Forest. Assumptions for the rapid assessment and SIMPPLLE model are clearly 

listed in the final report from the Ecosystem Research Group. The report also 

describes the level of certainty for projections of potential habitat by wildlife 

species. High certainty is attributed to projections for northern goshawk habitat 

due to an abundance of local data on nest locations. In contrast, projections for 

flammulated owl habitat are less certain. The National Forest had less data on 

nest locations for the owl, and the remotely-sensed vegetation data had low reliability for detecting key habitat features, such as low density Douglas-fir stands.

The assessment team regarded SIMPPLLE output as a “best guess” based upon 

current research on disturbance impacts, stand development, and characteristics 

of wildlife habitat. They decided that the rapid assessment would provide the 

most supportable results and applications for planning and project implementation if interpreted comparatively (e.g., Scenario X results in more acres of aspen 

cover type than Scenario Y) rather than predictively (e.g., Scenario X results in Z 

acres of aspen cover type).

8 This lesson learned reinforces material presented in Research Finding 3 of Chapter 5.
USDA Forest Service RMRS-P-70. 2014. 79

Meet the chapter presenters and authors

Barry Bollenbacher recently celebrated his 40th 

year with the Forest Service! He has served in his current 

position as Regional Silviculturist for the Northern Region 

since 1992. Barry works closely with researchers from the 

Rocky Mountain Research Station and other organizations 

to help incorporate science into silviculture prescriptions, 

forest plans, and regional training programs. Barry 

graduated from Michigan State University in 1975 with 

a bachelor’s degree in Forestry. Barry can be reached at 

bbollenbacher@fs.fed.us; 406-329-3297.

Rob Gump is the Forest Silviculturist and Ecologist for 

the Beaverhead-Deerlodge National Forest. Rob has held 

this position since 2008, as well as previously from 1990 to 

1996. He also spent 27 years with the Forest Service in the 

Northern and Pacific Northwest Regions. Rob is certified 

silviculturist, and he has been active with the fire and fuels 

management community for almost 30 years. Reach Rob at 

rgump@fs.fed.us; 406-683-3965.

Mike Hillis worked as a wildlife biologist for the Forest 

Service for 34 years, primarily in the Northern and Pacific 

Northwest Regions. He retired in 2003 and has since 

worked as the Senior Wildlife Biologist for the Ecosystem 

Research Group out of Missoula, MT. Mike specializes in 

long-term, broad-scale modeling for species potentially 

at risk in the northern and central Rockies. He graduated 

from Oregon State University in 1970 with a Bachelor’s 

degree in Wildlife Biology. Mike can be reached at mhillis@

ecosystemrg.com; 406-721-9240.

Claudia Regan is the Regional Ecologist with the Rocky 

Mountain Region of the Forest Service. She has worked 

with the agency as a full-time employee for 18 years and 

in temporary or seasonal capacities for 6 years. Regional 

Ecologists serve as applied scientists who bridge scientific 

research with resource management issues and work 

toward information synthesis, delivery, and application. 

Claudia has Bachelor’s and Master’s degrees in Forest 

Science from Southern Illinois University and a Ph.D. in 

Ecology from Colorado State University. Reach Claudia at 

cregan@fs.fed.us; 303-275-5004.

Literature cited

Chew, J.D, K. Moeller, C. Stalling. 2012. SIMPPLLE, version 2.5 user’s guide. 

General Technical Report RMRS-GTR-268WWW. U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 

363 pp. [online] URL: http://www.treesearch.fs.fed.us/pubs/40241.

Ecosystem Research Group. 2010. Beaverhead-Deerlodge rapid assessment. 

Prepared for the U.S. Department of Agriculture, Forest Service, BeaverheadDeerlodge National Forest. Ecosystem Research Group, Missoula, MT. 242 

pp. [online] URL: http://www.fs.fed.us/rmrs/docs/future-forests/references/

beaverhead-deerlodge-rapid-assessment.pdf.

Haufler, J. B. 1999. Strategies for conserving terrestrial biological diversity. Pp 17-

34 in R.K. Baydack, H. Campa III, and J.B. Haufler (eds.) Practical Approaches 

to the Conservation of Biological Diversity. Island Press: Washington, D.C. 
80 USDA Forest Service RMRS-P-70. 2014.

Common name Scientific name

Insect species

Western spruce budworm Choristoneura occidentalis

Lodgepole needle miner Coleotechnites milleri Busck

Mountain pine beetle Dendroctonus ponderosae

Tree species

Subalpine fir Abies lasiocarpa

Engelmann spruce Picea engelmannii

Whitebark pine Pinus albicaulis

Bristlecone pines P. aristata and P. longaeva

Foxtail pine P. balfouriana

Pinyon pines P. edulis and P. monophylla

Limber pine P. flexilis

Ponderosa pine P. ponderosa

Scotch pine P. sylvestris

Lodgepole pine P. contorta

Quaking aspen Populus tremuloides

Animal species

Northern goshawk Accipiter gentilis

Elk Cervus canadensis

Pileated woodpecker Dryocopus pileatus

Wolverine Gulo gulo

Canada lynx Lynx canadensis

Fisher Martes pennant

Flammulated owl Otus flammeolus

Lazuli bunting Passerina amoena

Black-headed grosbeak Pheucticus melanocephalus

White-headed woodpecker Picoides albolarvatus

Black-backed woodpecker Picoides arcticus

American three-toed woodpecker Picoides dorsalis

Downy woodpecker Picoides pubescens

Hairy woodpecker Picoides villosus

Chickadees Poecile spp.

Golden-crowned kinglet Regulus satrapa

Bull trout Salvelinus confluentus

Mountain bluebird Sialia currucoides

Pine squirrel Tamiasciurus hudsonicus

Grizzly bear Ursus arctos horribilis

Fungi species

Blue-stain fungus Grosimannia clavigera

Appendix A. Scientific names of insect, plant, animal, 

and fungi species.
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