This file was created by scanning the printed publication. 

Text errors identified by the software have been corrected; 

however, some errors may remain. 
Technical Sally Campbell is a pathologist, Pacific Northwest Region, PO Box 3623, Portland, OR

Coordinators 97208, and Leon Liegel is a research forester, Pacific Northwest Research Station,

3200 SW Jefferson Way, Corvallis, OR 97331.
Solutions for Forests East of the Cascades and in Southwest Oregon

• Thin stands to reduce competition, stress, and bark beetle susceptibility.

• Harvest certain species such as lodgepole pine to create a mosaic of age classes across the landscape to

prevent widespread outbreaks of bark beetles.

• Design site-specific regeneration (natural or planted) to promote desired species composition and

structure.

• Keep in mind the effects that certain activities (such as thinning, harvest, or re-planting with certain

species) will have on root diseases and dwarf mistletoes.

• Reduce forest-floor fuels to prevent destructive, stand replacement fires. Once fuels are reduced,

prescribed fire will be safer and more effective.

• Introduce prescribed fire that mimics natural, light ground fires to maintain a light fuel load and

remove fire susceptible species such as Douglas-fir and true fir in low elevation pine stands.

• Use fire to regenerate species such as larch or quaking aspen that depend on fire or other disturbance

to create appropriate seedbeds or stimulate root sprouting.

Solutions for Forests West of the Cascades

• In forested areas, shift stands from single species to multiple species to reduce insect outbreaks and

proliferation of diseases. Tradeoffs between maximizing timber production (traditionally with even-aged,

single species plantations) and minimizing insect and disease damage must be examined.

• Replant harvested or restored areas with seedlings grown from local seed-sources or use natural

regeneration. Severity of diseases such as Swiss needle cast is much less when trees are adapted to the site.

• Maintain a mosaic or mix of species and age classes, preventing the whole landscape from being

dominated by uniform, highly susceptible stands.

Solutions for Urban Forests

• Reduce air pollution through a variety of strategies and new technology so that production of ozone

and other pollutants that damage forests can be reduced or, at the very least, not increased.

• Maintain programs to monitor and eradicate exotic pests, and to prevent introductions.

• Plant and care for trees and other vegetation in urban areas.

• Manage for hazards such as fire, decay, and root disease in urban-forest interfaces.

The Future

Citizens, forest owners, and resource managers must all become active to solve forest health problems in Oregon

and Washington. Without cooperation and interaction among groups with diverse and opposing viewpoints, future

needs and desires for products and services from regional forests will not be met.

East of the Cascades, forest fuel reduction, thinning overstocked stands, and changing species are needed to reduce

the risks of uncontrollable, stand-replacing wildfires and widespread insect outbreaks.

West of the Cascades, the continued introduction of exotic insects, diseases, and plants threaten the existence of

native forests and, without continual vigilance, chances of establishment and spread are much greater. Air

pollution, unless controlled and reduced in the Puget Sound and Willamette Valley, will affect increasing numbers

of forest species, influencing their ability to grow and reproduce.

On both sides of the Cascades, the incidence and severity of many native insects and diseases is closely linked to

forest management. Awareness of the impact of different management activities on insects and diseases is

essential to successfully achieve desired forest conditions.

Forest management, forest health monitoring, research, and public education are the tools needed to create and

maintain the forests that are so important to the people of Oregon and Washington.
DISTURBANCE AND FOREST HEALTH IN OREGON AND WASHINGTON

A joint publication by the USDA Forest Service Pacific Northwest Research Station and Pacific Northwest Region,

the Oregon Department of Forestry, and the Washington Department of Natural Resources, 1996.

SUMMARY

Forest conditions in Oregon and Washington have been steadily changing for more than 100 years. Many

disturbance patterns in forest stands no longer occur with the same frequency or intensity as in the past and current

patterns are often outside the natural range of variation. Much of the change in disturbance regimes is due to fire

suppression, harvesting practices in the last century, and increased urbanization, industry, and commerce.

East of the Cascades

• Outbreaks of defoliating insects such as western spruce budworm and Douglas-fir tussock moth, are

now larger, more intense, and more frequent than in the past.

• Bark beetle mortality, associated with tree stress and overstocked stands, is more prevalent.

• Drought in the late 1980s and early 1990s, coupled with overstocking, contributed to increased

susceptibility of forest trees to bark beetles and other insects, fire, and disease.

• Many root diseases and dwarf mistletoes are more widespread and destructive because of past harvest

practices and the resulting changes in forest structure and species.

• Fire is less frequent now but more severe on low elevation, dry sites because of fuel buildup.

West of the Cascades

• Incidence and damage by native forest pathogens, particularly root diseases, have increased due to

past forest management practices.

• Periods of drought have contributed to susceptibility of trees to attacks by insects and pathogens.

Southwest Oregon

• The risk of fire and insect outbreaks has increased due to fire suppression, overstocked stands, and

periods of drought.

• Two exotic diseases, white pine blister rust and Port-Orford-cedar root disease, have significant

affected host species and how they are managed.

Urban Forests

• Introductions of exotic pests have increased greatly over the past century with increased commerce,

travel, and new people moving to the Northwest.

• Air pollution has increased in the Willamette Valley and Puget Sound areas with increased population

and industry. Ozone and other pollutants are capable of damaging forests near and far from pollutant

sources.

• Stresses on urban trees from air pollution, mechanical injury, and poor maintenance, have increased in

many cities and towns.

• Fire, wind, insects, and diseases are hazards to the trees, people, and homes in the urban-forest

interface.

Forest Health Monitoring

• National field protocols for the Forest Health Monitoring Program were tested west of the Cascade

crest on 13 plots in Oregon and 12 plots in Washington in 1994 to establish baseline forest conditions in

Douglas-fir habitats.

• Operational forest health monitoring across all habitats in Oregon and Washington is scheduled to

begin in 1997.

• Other surveys and inventories are on-going and continue to provide information on disturbance agents

and forest conditions.
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Corvallis, OR 97331

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Disturbance and Forest Health in

Oregon and Washington

Technical Coordinators:

Sally Campbell USDA Forest Service, PNW Region

Leon Liegel, USDA Forest Service, PNW Research Station

Editor:

Martha H. Brookes

Joint publication of USDA Forest Service, Pacific Northwest Research Station

and Pacific Northwest Region; Oregon State Department of Forestry; and

Washington State Department of Natural Resources

USDA Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report PNW-GTR-381

September 1996
ABSTRACT Campbell, Sally; Liegel, Leon, tech. coords. 1996. Disturbance

and forest health in Oregon and Washington. Gen. Tech. Rep.

PNW-GTR-381. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station, Pacific

Northwest Region; Oregon Department of Forestry; Washington

Department of Natural Resources. 105 p.

The scope and intensity of disturbance by such agents as fire,

insects, diseases, air pollution, and weather in Pacific Northwest forests suggests that forest health has declined in recent

years in many areas. The most significant disturbances and

causes of tree mortality or decline in Oregon and Washington

are presented and illustrated. We discuss the interrelations of

disturbance with forest management activities and the effect on

native trees and suggest some solutions for reducing the

severity of disturbance. One chapter reports on a forest health

monitoring pilot project.

Keywords: Air pollution, diseases, disturbance, fire, forest

health monitoring, insects, vegetation change, weather damage.
• National field protocols for the Forest Health Monitoring

Program were tested west of the Cascade crest on 13 plots in

Oregon and 12 plots in Washington in 1994 to establish

baseline forest conditions in Douglas-fir habitats.

• Operational forest health monitoring across all habitats in

Oregon and Washington is scheduled to begin in 1997.

• Other surveys and inventories are ongoing and continue

to provide information on disturbance agents and forest

conditions.

• Thin stands to reduce competition, stress, and bark beetle

susceptibility.

• Harvest certain species such as lodgepole pine to create a

mosaic of age classes across the landscape to prevent widespread outbreaks of bark beetles.

• Design site-specific regeneration (natural or planted) to

promote desired species composition and structure.

• Keep in mind the effects that certain activities (such as

thinning, harvest, or replanting with certain species) will have

on root diseases and dwarf mistletoes.

• Reduce forest-floor fuel to prevent destructive, stand replacing fires. Once fuels are reduced, prescribed fire will be safer

and more effective.

• Introduce prescribed fire that mimics natural, light, ground

fires to maintain a light fuel load and remove fire-susceptible

species, such as Douglas-fir and true fir, in low-elevation pine

stands.

• Use fire to regenerate species such as larch or quaking aspen

that depend on fire or other disturbance to create appropriate

seedbeds or stimulate root sprouting.

• In forested areas, shift stands from single to multiple species

to reduce insect outbreaks and proliferation of diseases.

Tradeoffs between maximizing timber production (traditionally

with even-aged, single species plantations) and minimizing

insect and disease damage must be examined.

• Replant harvested or restored areas with seedlings grown

from local seed sources or use natural regeneration. Severity

of diseases such as Swiss needle cast is much less when trees

are adapted to the site.

• Maintain a mosaic or mix of species and age classes, preventing the whole landscape from being dominated by uniform,

highly susceptible stands.

Solutions for Forests West

of the Cascades

Solutions for Forests

East of the Cascades and in

Southwest Oregon

Forest Health Monitoring
Forest conditions in Oregon and Washington have been steadily

changing for more than 100 years. Many disturbance patterns

in forest stands no longer occur with the same frequency or

intensity as in the past, and current patterns are often outside

the natural range of variation. Much of the change in disturbance regimes is due to fire suppression, harvesting practices

in the last century, and increased urbanization, industry, and

commerce.

• Outbreaks of defoliating insects, such as western spruce

budworm and Douglas-fir tussock moth, are now larger, more

intense, and more frequent than in the past.

• Bark beetle mortality, associated with tree stress and overstocked stands, is more prevalent.

• Drought periods in the late 1980s and early 1990s, coupled

with overstocking, contributed to increased susceptibility to

insects, diseases, and fire.

• Many root diseases and dwarf mistletoes are more widespread

and destructive because of past harvest practices and the

resulting changes in forest structure and tree species.

• Fire is less frequent now but much more devastating on lowelevation, dry sites because of fuel buildup.

• Incidence and damage by native forest pathogens, particularly root diseases, have increased because of past forest

management practices.

• Periods of drought have contributed to susceptibility of trees

to attacks by insects and pathogens.

• The risk of fire and insect outbreaks has increased because of

fire suppression, overstocked stands, and periods of drought.

• Two exotic diseases, white pine blister rust and Port-Orfordcedar root disease, have significantly affected their host

species and how they are managed.

• Introductions of exotic pests have increased greatly over the

past century with increased commerce, travel, and new people

moving to the Northwest.

• Air pollution has increased in the Willamette Valley and Puget

Sound areas with increased population and industry. Ozone

and other pollutants can damage forests near—and even far

from—pollutant sources.

• Stresses on urban trees from air pollution, mechanical injury,

and poor maintenance have increased in many cities and

towns.

• Fire, wind, insects, and diseases are hazards to the trees,

people, and homes in the urban-forest interface.

Urban Forests

Southwest Oregon

West of the Cascades

East of the Cascades

SUMMARY
• Reduce air pollution through a variety of strategies and new

technology so that production of ozone and other pollutants

that damage forests can be reduced or, at the very least, not

increased.

• Maintain programs to monitor and eradicate exotic pests and

to prevent new introductions.

• Plant and care for trees and other vegetation in urban areas.

• Manage for hazards such as fire, decay, and root disease in

urban-forest interfaces.

Citizens, forest owners, and resource managers must all become active to solve forest health problems in Oregon and

Washington. Without cooperation and interaction among

groups with diverse and opposing viewpoints, future needs

and desires for products and services from regional forests

will not be met.

East of the Cascades, forest fuel reduction, thinning overstocked stands, and changing species are needed to reduce

the risks of uncontrollable, stand-replacing wildfires and

widespread insect outbreaks.

West of the Cascades, the continued introduction of exotic

insects, diseases, and plants threaten the existence of native

forests and, without continual vigilance, chances of establishment and spread are much greater. Air pollution, unless

controlled and reduced in the Puget Sound area and the

Willamette Valley, will affect increasing numbers of forest

species, influencing their ability to grow and reproduce.

On both sides of the Cascades, the incidence and severity

of many native insects and diseases is closely linked to forest

management. Awareness of the effects of different management activities on insects and diseases is essential to achieve

desired forest conditions.

Forest management, forest health monitoring, research,

and public education are the tools needed to create and maintain the forests that are so important to the people of Oregon

and Washington.

Solutions for Urban Forests

The Future


AUTHORS Chapter I

Sally Campbell is a plant pathologist, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region, P.O. Box 3623, Portland,

OR 97208.

Karen Ripley is an entomologist, Washington Department of Natural

Resources, P.O. Box 47000, Olympia, WA 98504-7037.

Ken Snell is a forester, U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, P.O. Box 3623, Portland, OR 97208.

Chapter 2

Andy Eglitis is an entomologist, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region, Deschutes National Forest,

1645 Highway 20 East, Bend, OR 97701.

Ellen Goheen is a plant pathologist, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region, J. Herbert Stone Nursery,

2602 Old Stage Road, Central Point, OR 97529.

Alan Kanaskie is a plant pathologist, Oregon State Department of

Forestry, 2600 State Street, Salem, OR 97310.

Dave Overhulser is an entomologist, Oregon State Department of

Forestry, 2600 State Street, Salem, OR 97310.

Chapter 3

Robert Backman is an entomologist, Washington Department of

Natural Resources, P.O. Box 47000, Olympia, WA 98504-7037.

Jerome Beatty is a plant pathologist, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region, Columbia Gorge Ranger

District, 31520 SE Woodard Road, Troutdale, OR 97060.

Karen Ripley is an entomologist, Washington Department of Natural

Resources, P.O. Box 47000, Olympia, WA 98504-7037.

Kenhelm Russell is a plant pathologist, Washington Department of

Natural Resources, P.O. Box 47000, Olympia, WA 98504-7037.

Chapter 4

Alan Kanaskie is a plant pathologist, Oregon State Department of

Forestry, 2600 State Street, Salem, OR 97310.

Gene Milbrath is a plant pathologist, Oregon State Department of

Agriculture, 635 Capitol Street NE, Salem, OR 97310-0110.

Paul Ries is an urban forester, Oregon State Department of Forestry,

2600 State Street, Salem, OR 97310.

Chapter 5

Leon Liegel is a research forester, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station, 3200 Jefferson

Way, Corvallis, OR 97331.

Chapter 6

Sally Campbell is a plant pathologist, U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region, P.O. Box 3623, Portland,

OR 97208.

LeRoy Kline is an entomologist, Oregon State Department of Forestry,

2600 State Street, Salem, OR 97310.
ACKNOWLEDGMENTS The following people are gratefully acknowledged for their

invaluable contributions to this report.

Layout and Design

John Me and Delbert Thompson.

Artwork, GIS Products, Photography, and Graphics

Richard Busing, Tom Iraci, Shelley Hayden, Julie Johnson,

Russel Mitchell, Mike O'Day, Gail Saunders, Craig Schmitt,

Beverly Swanson.

Aerial Survey, Climate, Fire, Insect, and Disease

Information and Data

Kathleen Johnson, Craig Schmitt, Don Scott, Keith Sprengel,

Dick Stender, Levi Strauss, George Taylor, Mike Ziolko.

Typing and Revising

Marian Ely and Virginia Hokkanen.

Review of the Draft Report

Bob Alverts, Bill Burkman, John Dale, Greg Filip, Susan Frankel,

Andrew Gillespie, Fred Hall, Jim Hadfield, Robert Mangold,

Barbara Ross, Darrell Ross, Susan Sater, Kathy Sheehan,

Gordon Schmitt, Dewey Tate.
CONTENTS

CHAPTE R I AN OVERVIEW OF DISTURBANCE AND FOREST

HEALTH IN OREGON AND WASHINGTON 2

Introduction 2

Forest Health Defined 2

What Is at Stake 2

Assessing Forest Health 2

This Report 5

Sources of Information 5

Scientific References and Names 5

Changes In Forest Vegetation 6

Forest Succession 6

American Indian and Pioneer Influences 6

Logging and Tree Farming 7

Fire Suppression 8

Vegetation, Past and Present 8

Tree Mortality 11

Ecological Role of Mortality 11

Patterns of Mortality 11

Normal Mortality 12

Mortality Trends 12

Weather and Its Influence On Forests 13

Short-Term Weather Events 14

Long-Term Weather Changes 15

The Future 16

Exotic Pests 16

Problems With Exotics 16

Introduction of Exotic Pests 18

Reducing Introductions 19

Control and Eradication 19

Effects of Air Quality 19

Ozone 19

Lichens As Bioindicators 21

Acidity of Cloud Water 21

Monitoring Methods 21

Aerial Survey 21

Forest Inventory 22

Forest Heath Monitoring Plot Network 22

New Monitoring Technology 23

Risk Rating 23
CHAPTER 2

CHAPTER 3

DISTURBANCE AND FOREST

HEALTH IN OREGON 24

Oregon Coast Range (M242A) and

Western Cascades (M242B) 25

Ecology 25

All Species 25

Douglas-Fir 26

Various Species 29

Willamette Valley (242A) 30

Ecology 30

All Species 30

Oregon White Oak 32

Ponderosa Pine 32

Grand Fir 32

Hybrid Poplar 32

Eastern Cascades (M242C), Modoc Plateau

(M261G), and Blue Mountains (M332G) 33

Ecology 33

All Species 33

Mixed Conifers 35

Western Larch 37

Pines 37

Various Species 38

Southern Cascades (M261D)

and Klamath Mountains (M26IA) 39

Ecology 39

All Species 39

Port-Orford-Cedar 41

Five-Needle Pines 42

Mixed Conifers 43

DISTURBANCE AND FOREST

HEALTH IN WASHINGTON 44

Washington Coast Range (M242A), Western

Cascades (M242B), and Puget Trough (242A) 45

Ecology 45

All Species 46

Douglas-Fir 47

Hemlock 49

True Fir 50

Hardwoods 51

Eastern Cascades (M242C)

and Okanogan Highlands (M333A) 53
CHAPTER 4

CHAPTER 5

CHAPTER 6

Ecology 53

Mixed Conifers 53

Pines 56

Aspen 58

DISTURBANCE AND URBAN FOREST HEALTH 60

Introduction 60

Disturbance Agents In Urban Settings 61

FOREST HEALTH MONITORING PILOT

PROJECT IN OREGON AND WASHINGTON 66

General Site and Species Characteristics 67

Stand Characteristics 68

Understory Vegetation 68

Overstory Vegetation 68

Basal Area 69

Crown Ratings 69

Sapling Crown Vigor 70

Crown Density 70

Crown Dieback 71

Foliage Transparency 71

Damage 72

Full-Hectare Tally 73

Vegetation Structure 74

Lichen Communities 75

Songbird Habitat Indicator 76

Conclusions 77

THE FUTURE OF OREGON AND

WASHINGTON FOREST HEALTH 78

East of the Cascades 79

West of the Cascades 81

Southwest Oregon 84

The Future 85

SELECTED REFERENCES 87

APPENDICES

Appendix A—Common and Scientific Names 88

Appendix B—Counties In

Oregon and Washington 19

Appendix C—1995 Cooperative

Aerial Survey Results 90

Appendix D—The National Forest

Health Monitoring Program 101
CHAPTER I. AN OVERVIEW OF DISTURBANCE

AND FOREST HEALTH IN

OREGON AND WASHINGTON

INTRODUCTION

People, livestock, insects, diseases, snow,

wind, fire, volcanic eruptions, earthquakes,

and floods are constantly disrupting forests,

slowing growth, and injuring or killing trees

and other living components of the ecosystem.

Disturbance is natural and necessary to forest ecosystems; without it, forests could not

regrow, recycle, and pass through successive

stages from seedlings to old growth. But, when

disturbance causes more continuous, severe,

or widespread effects than people consider acceptable or normal, the forest is described as

"unhealthy."

What Is at Stake?

More than 36% of the land area in Oregon

and Washington is forested. Forest land in the

two states includes more than 18 million acres

of federal land (19 National Forests, 7 Indian

Reservations, 4 National Parks, and almost 2.5

million acres managed by the Bureau of Land

Management), more than 2.8 million acres of

state land, and about 16 million acres of private industrial and nonindustrial forest land.

The residents of Oregon and Washington depend on these forests for wood products, jobs,

fisheries, recreation, scenery, school funding,

clean water, and many other products and

amenities. Much of what people value about

Forest Health Defined the Pacific Northwest is tied to the forests.

Forest health is a human

concept, and people have different views about what constitutes a healthy forest. As

demands on forests change

over time, so too will people's

views of forest health. Currently, two ideas are included

in most definitions of forest

health.

• A healthy forest maintains

its function, diversity, and

resiliency; and

• A healthy forest provides for

human needs and desires,

and looks the way people

want it to look.

A healthy forest can

renew itself vigorously

across the landscape,

recover from a wide

range of disturbances,

and retain its ecological

resilience while meeting

current and future needs

of people for values,

uses, products, and

services. Adapted from:

Forest Health Policy, USDA

Forest Service, 1996.

Assessing Forest Health

Forest health is assessed by

monitoring the condition of

various parts of the forest. Certain traits, such as tree

growth, crown condition, mortality, and lichen communities, are good indicators of forest health. The condition of

these indicators is used to

characterize the forest as

healthy, unhealthy, or something in between. Over time,

monitoring shows changes in

forest condition. Forest ecosystems age just as people do,
so some yearly change is natural. Unexpected

and large changes, though, would be cause for

concern and lead to further investigations.

Detecting trends in forest condition and predicting long-term consequences of significant

changes are the two cornerstones of monitoring activities. By knowing how and when forest conditions will change and what the ultimate consequence of these changes might be,

scientists, managers, and citizens can work together to plan alternative solutions and actions.

federal and state agencies and private organizations in Oregon and Washington monitor

forest health by using a variety of surveys and

inventories.

Distribution of forest types in Oregon and Washington.

Source: Southern Forest Research Experimental Station, USDA Forest Service.

Over the past 45 years, the population of Oregon and Washington has

more than doubled (a 117%

increase); forest land in the two

states has shrunk only 16%.
Ecological units in Oregon and Washington. Information in chapters 2 and 3 is arranged by ecological

Sections. Source: Bailey et al. 1994.

Key

(sections addressed in this report are in bold):

Humid Temperate Domain

Marine Division (240)

Pacific Lowland Mixed Forest Province (242)

Willamette Valley and

Puget Trough Section(242A)

Marine Regime Mountains (M240)

Cascade Mixed Forest—Coniferous Forest—

Alpine Meadow Province (M242)

v Oregon and Washington Coast

/ Range Section (M242A)

Western Cascades Section (M242B)

Eastern Cascades Section (M242C)

Mediterranean Regime Mountains (M260)

Sierran Steppe—Mixed Forest—Coniferous

Forest—Alpine Meadow Province (M26I)

Klamath Mountains Section (M26IA)

Southern Cascades Section (M26ID)

Modoc Plateau Section (M26IG)

Dry Domain

Temperate Steppe Division (330)

Great Plains—Palouse Dry Steppe Province (331)

Palouse Prairie Section (331 A)

Temperate Steppe Regime Mountains (M33O)

Middle Rocky Mountains Steppe—

Open Woodland—Coniferous Forest—

Alpine Meadow Province (M332)

Blue Mountains Section (M332G)

Northern Rocky Mountain Forest Steppe

Coniferous Forest—Alpine Meadow

Province (M333)

Okanogan Highlands Section (M333A)

Temperate Desert Division (340)

Intermountain Semi-Desert Province (342)

Northwestern Basin and Range Section (342B)

Owyhee Uplands Section (342C)

High Lava Plains Section (342H)

Columbia Basin Section (3431)
Ownership of forested land in Oregon (left) and Washington (right).

This Report

This report was written to help people understand the disturbances at work in the forests of Oregon and Washington, their significance, the underlying causes, and possible

actions to improve forest health. The disturbance agents we discuss in the following

chapters are insects, diseases, weather, air

pollutants, and fire. We also recognize that

people are agents of forest disturbance, and

the results of people's activities in the forest—such as fire suppression, tree harvest,

tree planting, and restoration work—are woven into our discussions as well.

Chapter 1 is devoted to some forest health

topics that people in both states are concerned about: vegetation change, mortality,

weather trends, exotic pests, and air pollution. We also include a section on forest

health monitoring methods.

The next two chapters contain information

specific to each state (chapter 2, Oregon;

chapter 3, Washington). Information in

these chapters is arranged by ecological sections because disturbance agents and patterns are generally tied to the geography, climate, and vegetation that make up an

ecological section. We also show which

counties correspond to the ecological section

being discussed.

Chapter 4 describes disturbance agents and their effects on the health of urban

forests in Oregon and Washington. Chapter 5 describes

a forest health monitoring

research project carried out

in the Pacific Northwest in

1994. And chapter 6 is a

summary of the disturbances at work in Pacific

Northwest forests, our expectations of future disturbances and forest condition,

and some strategies for improving forest health in Oregon and Washington.

Sources of Information

The primary sources of data for insects

and diseases in this report are the cooperative (Forest Service and states) aerial survey, flown over all forested lands in Oregon

and Washington each year; special aerial

surveys for specific problems; various

ground surveys; and forest insect and disease research. Information on fire, weather,

and air quality came from specialists in the

Forest Service and state agencies who, in

turn, obtained their data from regional monitoring networks for those resources. Much

of the information on ecological relations between trees and disturbance agents is based

on the field experience of the pathologists,

entomologists, ecologists, and fire and air

specialists who contributed to this report.

References and Scientific Names

To enhance readability, we have not cited

references or included scientific names of

trees, insects, and fungi in the text. Selected references are listed at the end of

chapter 6. Scientific names are listed in appendix A, alphabetically by common name.
CHANGES IN FOREST

VEGETATION

The amount, variety, age,

and size mix of trees on a site

determine the extent and severity of damage by disturbance agents. Changes in

forest vegetation affect forest

health.

Thirteen thousand years

ago, glaciers still covered

much of North America. As

the continent warmed, about

10,000 years ago, glaciers receded and coniferous forests

expanded their range. Fossils from Mount Rainier suggest that the period from

6,000 to 3,400 years ago was

actually warmer and drier

than the current climate.

Subalpine fir, Douglas-fir, ponderosa pine,

noble fir, and lodgepole pine were common.

California chaparral vegetation extended as

far north as Vancouver Island. Fires were

probably very frequent. The current cooler,

wetter period began about 3,500 years ago,

and fire frequency declined.

Forest Succession

Forest succession is the change in species

composition as plants grow, die, and are replaced over time. A tree that thrives in a

sunny opening created by fire may not be

able to reproduce in the shady environment

of a mature forest. It will be replaced by a

more shade-tolerant species. In the absence

of disturbances that create openings, shadetolerant climax species eventually dominate.

Type, diversity, and frequency of disturbances interact with site factors such as soil

type, topography, weather, climate, and surrounding vegetation to influence which

plants invade a site after disturbance and

how communities develop. People can affect

plant succession by altering the type, severity, and frequency of disturbances.

Millions of logs were moving out of the Northwest by the turn of the

Century. Photo courtesy of Oregon Historical Society (neg. 45791).

American Indian and Pioneer Influences

Native people modified the vegetation of

the Pacific Northwest—both accidentally and

deliberately. Fires set on sites such as Puget

Sound's Whidbey Island, the Willamette Valley, and the eastern slopes of the Cascade

Range enhanced the growing of bracken, camas, huckleberries, blueberries, and

grouseberry and attracted browsing animals

like deer and elk.

Early non-native visitors and settlers also

modified the forest environment in Oregon

and Washington. In many places, the virtual elimination of beaver by trapping for

their pelts drastically altered riparian systems. Settlers copied the American Indians'

technique of attracting grazing animals by

setting many, sometimes devastating fires.

Settlers also brought new species to the area:

sheep, cattle, cheat grass, wheat, potatoes.

Use of forests was initially limited to local

demands for construction materials, firewood, and fencing. Some forest lands were

converted to agriculture, town sites, and

residential areas so, in some places, forest

depletion became an issue.
Clearcutting and replanting Douglas-fir from the 1940s through the

1970s created the mosaic of even-aged, single-species plantations

visible today in much of western Oregon and Washington.

Logging and Tree Farming

Logging in the Pacific Northwest created

many changes in forest vegetation both east

and west of the Cascade crest. The forest

industry gained momentum in Washington

and Oregon in the late 1800s. The Puget

Sound area had major shipping ports. Lumber was sent to San Francisco and helped

build many West Coast cities. Logs were

dragged out of the woods by oxen, horses,

and mules and floated to steam-powered

mills. By the turn of the century, narrowgauge railways provided access to remote,

rugged areas. Steam-donkey engines on

skids and high-lead cables pulling logs above

the forest floor made log removal easier and

reduced soil compaction. Railroads allowed

efficient transport of material to markets in

the East, where ponderosa pine and western white pine from eastern Washington and

Oregon were highly prized. Low shipping

rates allowed Puget Sound producers to compete for interior markets, as well as continue

to supply worldwide customers.

Beginning in the early

1900s, mechanized equipment was used extensively.

From about 1910 to 1940,

the lumber market was glutted. Land owners suffering

major economic hardships

during this period were

forced to liquidate stumpage

to pay for the land or other

investments. They extracted

only the most valuable logs

as quickly as possible, leaving "weed" trees standing

and high volumes of fuels lying on the ground. Sparks

from steam engines and railroads started many fires,

and burns through logging

debris were hot and damaged

the soil, seedlings, and remaining trees.

After World War II, the logging industry struggled to keep up with demand for wood products. Gas-powered

chain saws and diesel and gasoline-powered

trucks and tractors improved logging efficiency and reduced fire hazard. Removal of

all wood within reach of cable settings

(clearcutting) increased because of operational efficiency and ease of regenerating new

forest in the Douglas-fir region. Slash burning was standard.

By the 1950s, the most productive portions of Pacific Northwest forests were being managed to maximize timber production.

When cutover sites were replanted, Douglasfir was usually the only species planted on

the west side and ponderosa pine on the east

side. Although the prevalence and distribution of species changed somewhat after logging and replanting, the planted seedlings

did not always thrive, and native species often partly or completely revegetated harvested areas.

CONTINUED
Beginning in

1944, Smokey

Bear posters

encouraged

the public to

help prevent

forest fires.

Photo courtesy of the

National Archives.

Historical fire regimes ranged

from mild, ground fires

(above) every 10 years or so

in low-elevation pine stands

to intense, stand-replacing

fires (left) at longer intervals

in high-elevation, mixed

conifer stands.

Fire Suppression

Fire fighting gained momentum after huge

fires at the turn of the century. For example,

the Yacolt fire in 1902 burned nearly

239,000 acres in Clark and Skamania counties (Washington) and killed 38 people. Several fires, including the Columbia fire near

Mount Hood, burned more than 170,000

acres in Oregon the same year.

Society demanded that the forests be protected. Laws regulating slash and slashburning to protect forests were passed in

1911. Permits were required for burning

slash in summer, and all snags over 25 feet

had to be cut. A highly efficient and coordinated forest fire-fighting force was developed

nationwide to aggressively attack and

quickly control all wildfires. Fire-fighting efficiency increased dramatically after World

War II when airplanes became available for

detecting and suppressing fires. Campaigns

such as "Smokey Bear" encouraged all citizens to help prevent forest fires.

Vegetation, Past and Present

Today's forests are different in composition and structure from the presettlement

period. Pacific Northwest forests have always been affected by disturbances (such as

fires, wind storms, volcanic eruptions, and
Vegetation change west of the Cascades. Western Oregon and Washington have had large changes

in forest vegetation over the past century, before European settlement (left), trees and tree species

were more numerous; valleys contained many hardwoods; snags were common; and abundant woody

material contributed to periodic widespread fires. In the last 100 years (right), much of the forest in

the Puget Sound area and Willamette Valley has been converted to cities, suburbs, and farms; on

slopes and mountains of the Coast and Cascade ranges, many forests are younger, less diverse, and

more fragmented as the result of years of timber harvesting and replanting. Artwork by Beverly Swanson.

landslides). Disturbances west of the Cascades—predominantly wind storms and

wildfire—rarely removed all large woody debris. Fires usually burned during periods

of extremely dry weather, and generally several fires were required to consume the

wood. Snags, large trees, and unburned

patches survived. Wide age ranges in natural Douglas-fir forests suggest slow

recolonization because seed sources were

absent after large disturbances.

The activities of the increasingly intensified timber industry also disturbed the forests, but they did not mimic the natural disturbances. Today's commercial forests are

younger, artificially dominated by even-aged

Douglas-fir, have few snags and logs, and are

more fragmented than less intensively managed forests or wilderness. Erosion and soil

loss are chronic problems associated with

roads and annual logging operations rather

than periodic problems associated with

natural fires.

East of the Cascades, disturbances ranged

from frequent, mild, ground fires at low elevations to occasional, intense, stand-replacing fires at high elevations. The suppression of fire took away an important

natural means for removing fuels and thinning stands, leaving sites dense with tree

cover, particularly at low elevations. Fire

suppression and the selective harvest of

large pines transformed many open, parklike stands dominated by large pines, into

dense, overcrowded stands of predominantly

Douglas-fir and grand fir. Riparian areas

were altered by grazing and loss of beaver

and pool-stabilizing logs. Grazing also affected fire intensity and frequency and, as a

result, understory species and stocking.

High-elevation forests with longer natural

fire frequencies have been less affected by

fire suppression than were stands at low elevations.

The forested area in Oregon and Washington faces increasing pressure from human

populations. Road building, urban development, agriculture, power lines, and reservoirs have all taken their toll on forested

acres. At the same time as worldwide demand for forest products is increasing, demand for beautiful tree-covered recreation

and home sites is also rising. Conflicting

management objectives for wood products,

attractive living spaces, and forested recreation sites will require resolution or compromise.

The ecological effects of these forest

changes are reflected in changes in the disturbances that forests experience. Hemlock

Overview—9
looper, a pest of old-growth hemlock stands

that once killed trees on huge tracts of forest, now has much less host material available and is much less damaging. Injury to

dense young trees caused by bear and bark

beetles is increasingly common. On sites

once dominated by pine, outbreaks of insects

that consume Douglas-fir and true fir foliage, and damage by root diseases and dwarf

mistletoes have increased in frequency and

severity. In some areas, fires are much more

devastating than before because of high fuel

loads.

Vegetation change east of the Cascades in mixed conifer forests. Mixed stands of Douglas-fir;

true fir; Ponderosa, lodgepole, and white pines; and western larch are common in eastern Oregon

and Washington, particularly at middle and high elevations. Before the turn of the century (left),

disturbance by fire, insects, and disease was variable, creating mosaics of forest and openings.

Fire suppression over the last 50 years has led to increased forest density with more fuels, insect

outbreaks, and diseases (right). Fires are now more intense and destructive; homes built in or near

forests are at increased risk. Artwork by Beverly Swanson.

Vegetation change east of the Cascades in Ponderosa pine forests. At lower elevations in eastern

Oregon and Washington, open, parklike stands of Ponderosa pine were common before 1900 (left).

Frequent, low-intensity fires kept fuels low and killed most seedlings and thin-barked firs, allowing the

pine to grow large and dominate. Fire suppression over the last 50 years changed these stands to

dense mixtures of Ponderosa pine, Douglas-fir, and true fir (right). Plant and animal diversity

increased. Fires are now infrequent and more severe. Changes in species and over-crowding

have increased susceptibility of these stands to bark beetles and defoliating insects.

Artwork by Beverly Swanson.
Death of trees is necessary

and beneficial in forested ecosystems, although excessive

mortality may indicate a forest

out of balance.

TREE MORTALITY

One obvious indicator of

potential poor forest health is

conspicuous numbers of dead

and dying trees.

Death of trees is normal,

but the causes and patterns

of mortality are complex. Insects, diseases, drought, wind

storms, and fire have killed

trees throughout millennia.

More recently, other agents associated with people and their

industry—air pollution, human-caused fire, and forest

management activities—are

contributing to tree mortality.

Factors such as competition

with other trees or plants or being eaten by grazing animals

like deer and elk can also cause

tree death. Often, death is the result of a combination of causes. For example, competition

and drought may stress a tree to such an extent that insects can attack and kill it.

Ecological Role of Mortality

Death of forest organisms is a necessary

part of every forest ecosystem and part of the

normal cycling of materials and processes.

Tree death contributes woody material to the

forest floor where it serves as moisture reservoirs and as habitat for a variety of plants,

animals, and microorganisms. The wood

and foliage eventually decompose, returning

nutrients to the soil. Standing dead trees

provide shelter, nesting, roosting, and hunting spots for birds and other animals. Trees

that fall in or near streams give the stream

the structure it needs to support fish and

other aquatic organisms. Tree death creates

an ever-changing mosaic of habitats within

a forest, allowing light to reach the forest

floor, seeds to germinate, and new vegetation to grow.

Patterns of Mortality

Patterns of mortality are complex. The

distribution of mortality from disturbances

is determined by patterns

of vegetation, the type of

disturbance agent, and

the physical environment.

Where species and structure

are similar over a large contiguous area, larger and

more severe corresponding

disturbances are more likely.

Where the forest is less uniform, mortality is patchy and

tends to correspond to

groups of susceptible species, ages, and structures.

Some disturbances cause

widespread mortality in

stands of uniform species

and age, such as mountain

pine beetle in even-aged

lodgepole pine. Other disturbance agents, like dwarf

mistletoe and western

spruce budworm, are favored by multistoried

stands where seeds and larvae can drop from

tall to short trees. Fire is more deadly in

multistoried stands where the understory

acts as a fuel ladder, allowing the fire to

reach the tree tops.

Wind storms, like those in Oregon in winter

1995, blow trees down and snap off tops and

branches. Mortality is severe in relatively small

areas and often scattered.
Insect outbreaks can kill millions of trees, particularly when susceptible

trees are grouped together, giving the insect an unbroken source of food

and breeding habitat

Normal Mortality

Many scientists and forest managers use

historical conditions (from 1600 to 1850, before European settlement of the West) as the

yardstick for determining "normal" conditions.

Old journals, photographs, maps, and tree-ring

analysis can be used to trace and compare historical forest composition, distribution, and

disturbances with current conditions and disturbances. Such analyses have shown that

disturbance patterns and mortality are outside

the historical range of variability in some areas of Oregon and Washington.

For example, western spruce budworm outbreaks in northeastern Oregon are more frequent and severe now (some stands have more

than 80% overstory mortality) than they were

in the 1800s, largely as a result of the selective harvest of nonhost species (ponderosa pine

and western larch) and fire suppression. These

two practices have led to dense, multistoried

stands of predominantly budworm-susceptible

species (true fir and Douglas-fir).

Many places in eastern

Oregon and Washington

have dense secondgrowth ponderosa pine

stands that replaced

open, parklike stands of

old-growth ponderosa

because of fire suppression. These overstocked

stands are extremely

susceptible to attack by

bark beetles. The number of stands in this condition and the resulting

mortality is higher than

in the past.

Fire frequency and severity have changed significantly over the past

century as a result of fire

suppression practices

and increases in tree

densities and flammable

materials. When fires occur, they are much more severe and kill more

trees on each burned acre.

Mortality Trends

Recent trends in mortality can be tracked

through forest inventories or surveys. Most

survey and inventory data are relatively recent.

The first aerial insect surveys began in the

1940s, and the first forest inventories began

in the 1930s. Comparing data from year to

year is useful and shows areas with potential

problems.

Tree mortality in western Washington and

northwestern Oregon has been, and probably

will continue to be, relatively low with occasional local areas of high mortality from disturbances such as flooding, wind storms, fire,

and insect outbreaks. The most significant

mortality agent on the west side is root disease. Although not highly visible, root disease

causes mortality on 10% of all lands in the

Pacific Northwest and may kill more than 50%

of a stand over a period of years.

In eastern Oregon and Washington, forest

inventories show mortality has been above
Mortality for five-year periods detected by annual aerial surveys. Trends can be seen, such as decreasing

mortality in the Blue Mountains (northeastern Oregon) and increasing mortality in south-central Oregon.

Source: Cooperative Aerial Survey, Oregon Department ofForestry.Washington Department of Natural Resources and USDA Forest Service.

average over the past decade on both federal

and nonfederal lands. Typical annual mortality in Oregon and Washington forests, based

on 60 years of inventory data, is about 0.5%

of the volume of wood present. The last inventories of eastern Oregon and Washington

forests (excluding National Forests) show annual mortality at 0.84% for eastern Washington and 0.97% for eastern Oregon. National

Forest inventory data show similar trends.

Annual aerial surveys for insect damage

show that mortality visible from the air (mainly

overstory trees; understory trees are difficult

to see) has actually decreased in most of eastern Oregon and Washington over the past few

years, after a period in the late 1980s when

mortality from bark beetles was very high.

Reduced mortality in the last few years may

be due to increased summer rains which lessen

tree stress and to the collapse of the current

western spruce budworm outbreak.

WEATHERAND ITS INFLUENCE

ON FORESTS

Weather influences forest health by directly

damaging trees and by affecting the ability of

trees to protect themselves against insects and

diseases.

The climate of the Oregon and Washington

is generally mild with dry summers. Great

variation in local areas is due to the influence

of elevation, proximity to the ocean, the northsouth mountain ranges, and prevailing storm

paths. Differences in dominant vegetation reflect differences in climate across the region

and the effects climate and weather have on

plants.

The climate of western Oregon and Washington is strongly seasonal with less than 20%

of the precipitation falling from May through

July, the growing season for trees. The coastal

areas have a maritime climate characterized
by mild temperatures; prolonged cloudy periods; wet winters; cool, dry summers; and a

long, frost-free season. Coastal mountains

cause rain shadows that alter this maritime

climate in the Puget Trough and Willamette

Valley, making the summers warmer and the

winters colder and reducing annual precipitation. With the rain shadows compounded by

southerly latitudes, southwestern Oregon's

valleys are still hotter and drier.

East of the Cascade Range, temperatures

fluctuate more widely than in coastal areas,

winters are colder, summers are hotter, and

frost-free seasons are shorter. Although precipitation is considerably less than on the west

side, it is much more uniform throughout the

year. May and June are the months with the

highest precipitation in some areas east of the

Cascades.

Short-Term Weather Events

Short-term weather events damage trees but

are part of normal climate variation. Various

kinds of weather kill trees outright or affect

their susceptibility to injury, disease, or insect

attack. Spring freezes shrivel tender foliage.

Lightning damages portions of trees and temporarily reduces their defensive capacity. Although most trees can survive short-term

flooding, complete submersion and silt buildup

around trunks restrict oxygen intake and

cause damage. Fungal spores enter tree

wounds caused by wind or snow breakage.

Many bark beetles take advantage of daily

water stress, attacking host trees on warm

summer afternoons when defenses are low.

The late 1980s and early 1990s in the Pacific Northwest were significantly drier than the

long-term average. Many places—including

Precipitation patterns in Oregon and Washington.

Extreme weather, such as wind storms (top), can

kill trees outright. Some types of weather, such

as hail (bottom), damage only parts of the tree

but make it more susceptible to diseases

and insects.
Conditions for winter wind

damage often are restricted to

a particular elevation, resulting

in a band of damage called

"red belt"

Winter Wind Injury: The process of transporting water from roots to foliage is passive.

Evaporation from the foliage, called transpiration, creates a deficiency of water at the top

of the tree. Additional water molecules are drawn up along the trees' conductive tissues

to replace molecules that leave the foliage. The resulting water column is like a drinking

straw. Additional liquid is drawn upward to replace any liquid removed from the top.

Injury can result to trees on warm, bright winter days. Pores on the foliage open to

receive carbon dioxide from the air. Water begins to evaporate from the leaves and additional water is drawn into the roots to replace it. Water moves slowly through cold soils,

however. The foliage loses water faster than roots can acquire it, causing the foliage and

upper branches to desiccate and die.

The precipitation record for the Willamette Valley

illustrates the cyclic pattern of moist and dry

periods in the Pacific Northwest source: Oregon Climate

Service, Oregon State University.

southwest Oregon, the Blue Mountains, the

Willamette Valley, and the Puget Sound area— experienced this drought. Outbreaks of some

insects, related to increased moisture stress

on trees particularly in overstocked stands, of- ten follow dry years. Over the last century in

the Pacific Northwest, the most recent drought

appears to be part of a cycle of wet and dry

periods each lasting 10 to 30 years. This cli- mate pattern is within a currently accepted

normal range of variability.

Long-Term Weather Changes

Long-term climate changes have and will

continue to produce changes in forests in Or- egon and Washington. The environmental vari- able that limits forests most and defines for- est community gradients is available moisture

during the dry summers. Long-term changes
in weather will also create changes in the intensity and frequency of natural disturbances,

such as wildfire and wind storms, which influence forest composition and structure.

If the climate becomes significantly warmer

and drier, forest communities may shift up

slopes to higher, cooler, moister elevations;

move to more northern latitudes; or move from

southern to northern aspects. Because each

plant species responds individually to the

unique interactions of temperature, moisture,

and site characteristics, some of the new communities are likely to be completely different

assemblages from any community dominant

today. Insects and diseases are likely to expand or contract their ranges along with their

hosts, but they may also change their behavior or habitat in unexpected ways.

Because tree species are long lived relative

to people, some of the forest changes caused

by climatic fluctuations might not be obvious

for decades or even centuries. Changes would

be greatest in places where many species are

already at their physiological limits (southwest

Oregon, for example). An increase in insect

and disease activity on relict populations,

stressed by harsh site conditions, would be expected.

The Future

A challenge facing climatologists, ecologists,

and land managers is to improve understanding of how dominant weather patterns are

likely to change—in both the short- and longterms—and how these changes will affect forests. Although the climate has shifted in the

past, determining if current trends in climate

indicate a true climate shift or just a change

within the normal range of variation is difficult. If a climate change is predicted, forest

managers will need answers to many questions. How large will the change be? How soon

is it expected to affect vegetation? How will

plants, insects, and diseases respond? How

will the industries and services that depend on

forest communities be affected? Can forests

be made more resilient to such changes?

EXOTIC PESTS

Trees have coevolved with their native pests

for thousands of years. Forest health can be

greatly affected when exotic pests are introduced and upset the balance.

Exotic plants and animals—those introduced from places outside of their native

range—can be harmful to native species. Many

introduced organisms are beneficial, such as

crop plants, ornamentals, game animals, and

livestock; these organisms were deliberately introduced and are essential to United States

commerce and society. In the Pacific Northwest, the exotics that cause the most damage

to forest trees are accidentally introduced insects and fungi. Introduced weeds are also destructive, competing with native forest vegetation for space, nutrients, and water.

Problems With Exotics

Without natural checks, the population of

an introduced pest can grow rapidly and wreak

havoc on the host organism. After a fungus

disease—white pine blister rust—was introduced 86 years ago, western white pine has

been significantly reduced in many Oregon and

Washington forests where it once was common.

The balsam woolly adelgid, an insect that was

introduced to the Pacific Northwest in the

1930s, has damaged grand fir at low elevations

in the Willamette Valley to such an extent that

most are unable to reproduce.

Exotic pests seriously affect Northwest forests. Damaged trees diminish the value of

property and recreation experiences. Revenue

is lost from recreation, forest products, and

real estate. Quarantines to prevent pest spread

disrupt and affect the costs of transporting

local forest products. Control efforts (such as

pesticide treatments or resistance breeding

programs) are expensive, and additional money

must be spent to replace killed or damaged

trees. In Oregon and Washington, the cost of

trapping, analysis, and eradication of gypsy

moth from 1985 to 1995 exceeded $50 million.

Most important, undesirable exotics change

forest ecosystems. Potential effects range from

slight decreases in native populations to per-
Young men, employed by the Civilian Conservation

Corps in the 1930s, were set to work pulling

Ribes bushes, the alternate host to the rust, in an

attempt to eradicate the disease. Photo courtesy of the

National Archives.

Blister rust is aptly named,

causing blister-like swellings

and eruptions of yellow

spores on branches and

stems of five-needle

pines. Once the entire

circumference of the branch

or trunk is infected, the

portion above dies.

White Pine Blister Rust: White pine blister rust was first found in the West in the

summer of 1921. The disease was identified on eastern white pine seedlings, imported

in 1910 from France and then planted at Point Grey near Vancouver, British Columbia.

By 1922, rust infections had been discovered at many points along the Washington

coast from the Columbia River north well into British Columbia. From that small beginning, this rust spread and infected all species of white pine found in the Pacific Northwest, including western white pine, sugar pine, and whitebark pine.

One early attempt at control was to eradicate the alternate host, currant or gooseberry

plants /Ribes spp.). Many men were hired by the Civilian Conservation Corps (CCC)

and Works Progress Administration (WPA) during the Great Depression years to pull

and burn ribes bushes in Northwest forests. As recently as the early 1950s, many

students worked their way through college pulling ribes. The cost of this program was

almost $100 million nationwide, with $62 million spent in the West.

By 1956, the rust had spread to most of the white pine forests in the United States,

and control efforts turned from ribes eradication and quarantine to managing the

disease, recognizing that it had now become a permanent part of many western forests. Management concentrated on developing pines resistant to the disease and

trying to return white and sugar pines to their previous roles in forested ecosystems.
Introduced plants, such as the English ivy

pictured here, can invade thousands of acres of

forest before they are recognized as threats to

native vegetation and wildlife.

manent alteration of biological communities.

Although much attention is directed at introduced insects and diseases, the current and

potential effect of introduced plant species on

forests is huge. Not only do exotic plants compete with native vegetation but they can also

change the physical and biological environment. Changes have been noted in moisture

and nutrient status, microbial populations,

and soil characteristics where exotic plants

have become established. Organisms dependent on native plants and adapted to a particular environment are also affected.

Introduction of Exotic Pests

Exotic pests usually travel to new areas as

hitchhikers. Weed seeds, fungus spores, insect

eggs, cocoons, or larvae arrive on plants, furRadiata pine wood chips in a Chilean ship hold.

Regulations require inspection and sampling.

Chemical or heat treatments are used to destroy

pests associated with chips.

niture, lawn mowers, logs, ships, cars, trailers, trains, and planes. Less frequently, they

are blown or washed in by storms or other

anomalous weather. Port-Orford-cedar root

disease is thought to have arrived in the Pacific Northwest on infected ornamental plants

in the 1920s; it then spread to both native PortOrford-cedar in southwest Oregon and ornamental Port-Orford-cedar throughout western

Washington and Oregon.

Increased travel, population expansion, and

new trade with South America, Japan, China,

and the former Soviet Union will contribute to

increased introductions of plants and animals

and increased chances that they will become

established once they arrive. The benefits of

economic growth for states such as Oregon and

Washington resulting from trade with other

countries has to be weighed against the risk

of introducing new pests and the potential

damage to forests. New regulations for imports

of logs and lumber (and other unmanufactured

wood items) have recently been implemented

by the states and the Animal and Plant Health

Inspection Service (APHIS), a branch of the U.S.

Department of Agriculture, to reduce the risk

of introducing forest pests into the United

States.
Reducing Introductions

Experts have suggested the following measures to slow introductions and prevent establishment of

exotic pests.

• Evaluate the potential for introducing harmful pests with imports.

• Increase inspection and quarantine efforts, especially as transporting and shipping technology

changes.

• Beware of accidentally introducing new plant species into forest

ecosystems.

• Maintain detection programs so

populations can be eradicated

while they are still small and localized.

• Promote self-sufficiency in wood

products so raw or unprocessed

products do not need to be imported.

Air pollution is created in and around Portland, Oregon. The effects on

vegetation are both short and long range because pollutants are

carried from the city to nearby forests by wind and fog.

Control and Eradication

A pest becomes established once it is able

to reproduce and maintain a population that

survives from year to year. For exotic pests

already established in Pacific Northwest forests, management strategies already in place

are minimizing their effects: natural enemies

such as predators and parasites are being released to control populations of some exotic

pests; resistance breeding programs are in

place for white pine blister rust and PortOrford-cedar root disease; and appropriate silviculture and pest management practices are

applied in many areas to minimize exposure

and spread. Unlike white pine blister rust or

Port-Orford-cedar root disease, the European

and Asian gypsy moths are not yet "established" in the Pacific Northwest. The moth

populations are still too low to breed effectively

and establish permanent populations. Eradication efforts, such as pesticide treatments, are

the most practical and effective at this

preestablishment stage. In 1996, ten urban

areas in the Northwest were treated for gypsy

moth to prevent their establishment.

EFFECTS OF AIR QUALITY

Air pollution alters the chemical environment

in which plants grow and affects the health of

the forest

The population in Oregon and Washington

is projected to increase into the future, and

with more people come more cars and other

services that cause air pollution. Washington

Environment 2010, a recent study by the State

of Washington and the Environmental Protection Agency, projects that over the next 15

years, concentrations of the pollutants of greatest concern to natural resource managers—

sulfur compounds, nitrogen compounds, and

ozone—will not improve. In fact, ozone is expected to increase by 30% in the Puget Sound

area unless additional actions are taken.

Air-quality work in Oregon and Washington

forests has focused on the effects of ozone on

vegetation, using lichens as air-quality

bioindicators, evaluating the sensitivity of alpine lakes to acid deposition, and determining the acidity of cloud water.

Ozone

Ozone is formed on warm sunny days from

hydrocarbons and nitrogen dioxide emitted by

cars and trucks. Unlike stratospheric ozone,
which protects life on Earth from the Sun's ultraviolet rays, ozone in the troposphere—created from nitrogen oxides and volatile organic

compounds by sunlight—is known to be unhealthy for people as well as plant life.

Ozone is generally a problem to forest vegetation only in the summer when plumes of

pollutants flow downwind from major urban

centers. Possible effects to vegetation include

visible leaf injury, reduced photosynthetic capacity, increased respiration, premature leaf

death, reduced growth, and mortality.

Ozone damages the most sensitive plants at

concentrations lower than those that are harmful to people. The federal human-health standard is 120 parts per billion (ppb). Lichens, a

group of ozone-sensitive organisms, can be

adversely affected at concentrations between

15 and 70 ppb. Effects on lichens are subtle

but can ultimately be fatal. Entire lichen species can disappear from the landscape before

anyone notices. Recent studies of native herbaceous seedlings and ozone profiles commonly found in the Pacific Northwest showed

that typical ozone concentrations could cause

damage and increase mortality of certain common species.

The Forest Service air program in Oregon

and Washington and the Washington Department of Ecology currently measure ozone electronically at Darrington, for the Glacier Peak

Wilderness; Packwood Lake, for the Goat Rocks

Wilderness; and Wishram in the Columbia

River Gorge. Ozone is also being measured in

wilderness areas by passive sampling, which

uses inexpensive coated filters that chemically

react at a known rate when exposed to different ozone concentrations. The next step is to

establish plots of ozone-sensitive species in the

highest ozone-exposure areas downwind of the

Puget Sound and Portland urban areas as another monitoring method.

Data clearly show

that ozone can

adversely affect

plant growth.

Medium exposure

is typical of ozone

concentrations west

of the Cascades.

Source: Mavity et al. 1995.

Passive

ozone

samples

are taken

on Mount

BakerSnoqualmie

National

Forest.

Table l-l—Effects of declining air quality on lichen communities in the Pacific Northwest

Air quality

Good

Decline beginning

Decline clearly visible

Poor

Very poor

Extremely poor

Effect on lichens

The most sensitive lichens are present and healthy. Diversity and biomass of lichens is high.

The most sensitive lichens are overgrown by other lichens or algae. Young individuals are absent.

The most sensitive lichens are missing on conifers; other lichens are still abundant. The remaining

lichens show high diversity and biomass.

The most sensitive lichens are missing on hardwoods and conifers. Some of the remaining lichens

show pollution effects. Diversity and biomass are intermediate to high.

The most sensitive lichens are missing. All of the remaining lichens show pollution effects;

diversity and biomass are intermediate.

All lichens show strong pollution effects (high frequency of dwarfed, shrubby, compact growth

forms; discoloration; fungal parasitism; and overproduction of dispersal propagules). Diversity

and biomass are low to nonexistent.
Lichens are indicators of

ozone and other pollutants.

Lichen species disappear as

pollution increases.

Lichens and mosses are "poikilohydric" organisms, meaning they cannot maintain constant internal moisture the

way most plants do. Daily drying and wetting cycles

concentrate pollutants dissolved in rain, fog, or dust in

tissues, independent of their sensitivity to air pollution.

Lichens are thus excellent accumulators of sulfur, nitrogen,

and metals, as well as more elusive but long-lived pollutants such as radioactivity and pesticides. Deposition

patterns and "hot spots" of specific air pollutants can be

mapped by analyzing their concentrations in samples of

lichens and mosses.

Lichens As Bioindicators

Lichens (plants made up of a symbiotic association of alga and fungus) are sensitive to

common pollutants in the Pacific Northwest:

sulfur dioxide; oxidants such as ozone, acid

rain, and fluorine; and some metals. Lichen

species vary in their sensitivity to different pollutants. The presence or absence of different

lichen species and the symptoms of pollution

injury can help locate places with relatively

high amounts of air pollution.

Lichens are being inventoried and monitored

extensively west of the Cascades. Initial analysis of monitoring results showed a curious absence of leafy, nitrogen-fixing (air-pollution

sensitive) lichens and an unexpected abundance of nitrogen-loving (pollution tolerant) lichens in the Willamette Valley and the Columbia River gorge.

Acidity of Cloud Water

Water in clouds and fog can become acidic

through interaction with atmospheric pollutants. Plants can absorb this acidic moisture

through aboveground parts or through their

roots after the moisture condenses and drips

to the ground. Acidic cloud water can inhibit

growth of sensitive species. Cloud water was

monitored during the summer of 1991 at Stampede Pass and Granite Peak in the Alpine Lakes

Wilderness, and during the summer of 1994

at Green Mountain in the Glacier Peak Wilderness. The minimum acidity of cloud water (pH

3.6) collected in 1991 for both sites was far

more acidic than is necessary to inhibit growth

of some species. Unfortunately, the only information currently available about effects on

local species is for conifer seedlings exposed

to acidic fog under controlled conditions. More

information is needed about the effects of

acidic cloud water, as well as injury thresholds to local species, before cause for concern

is verified.

MONITORING METHODS

Changes in forest health can be detected by

monitoring the condition of the forest.

Several monitoring tools and methods are

available for measuring the forest. Some have

been used for years; others are new and have

had only limited use. Many forest monitoring

programs, such as forest inventories, focus primarily on vegetation condition and change.

Other parts of the environment—like weather,

air quality, riparian habitat, fisheries, and wildlife—are measured in separate surveys or, more

recently, in multiresource surveys.

Aerial Survey

The Forest Service and the States of Oregon

and Washington began a cooperative aerial

survey for insect damage in 1947; only National

Forests and some state lands were surveyed.

From the 1960s and continuing to the present,

all forested lands in the two states, regardless

of ownership, are surveyed by air. The states

also fly special aerial surveys to track specific
The aerial survey maps areas of mortality and defoliation in

Oregon and Washington forests each summer. It is a cooperative effort by the Forest Service and the two state

Forestry Departments.

problems, such as bear damage in coastal Oregon forests.

Survey results are used by Forest Service

and state resource managers to track the approximate location and acreage of dying or

damaged trees, to follow cycles of insect outbreaks, and to predict future

damage. Land owners and managers use survey results to locate

areas of insect or disease damage on their lands and to aid

them in management decisions.

Forest Inventory

The Forest Service began to

inventory the timber resource on

federal, state, and private lands

in the 1930s. In 1993, the National Forest inventory in Oregon

and Washington was changed to

a multiresource survey, in which

understory vegetation, forest

floor woody material, wildlife

habitat, and damage agents are

also recorded.

Forest inventories are groundbased (rather than aerial); they

now consist of a series of systematically located plots that are

remeasured periodically, at 8- to

10-year intervals. Data from the

plots are pooled to provide an estimate of forest condition across

any grouping, geographic or biological.

Forest Heath Monitoring Plot

Network

A network of forest health

monitoring plots has been established on forested land of all

ownerships across the United

States. It consists of a series of

ground plots on which variables,

selected because scientists

thought they would be good indicators of forest health, are

measured. Although some variables are the same as inventory

measurements, others are quite different, such

as tallying the number and diversity of lichens

as indicators of air quality.

Forest Health Monitoring is a national program,

a partnership between several federal and state

agencies. The program was started in the Northeast in response to concerns about acid rain and

Inventory crews visit permanent plots periodically to measure

and record a variety of attributes such as tree size, understory

vegetation, woody material, and damage.

CONTINUED
now includes 19 states. Oregon and Washington

established and measured 25 plots in 1994 as a

pilot project (see chapter 5 for results of the pilot

project). The two states are scheduled to fully

implement the program in 1997. The purpose of

the Forest Health Monitoring program is to determine the condition of forests over large areas, such

as the West or the entire United States, and to detect changes in forest health at a broad scale.

New Monitoring Technology

The launching of satellites and the explosive

growth in computer technology have created

many possible applications of new technologies to forest monitoring. Commercially available satellite imagery of forested land can be

sorted and classified to identify species composition, tree size, and canopy density for any

given area of forest. Changes in vegetation can

be detected by periodic comparisons of satellite images. In Oregon and Washington, satellite imagery of the National Forests is being

purchased, classified, and used by the Forests.

Geographic information systems (GIS) are

used extensively to store and retrieve aerial

survey and other monitoring data. These systems geographically reference each piece of information and allow maps to be made that include many layers of data. Another new

technology is the global positioning system

(GPS). Using signals from several satellites, a

portable GPS unit can calculate the precise location of a field plot. Currently, GPS units are

taken to each forest inventory plot to record

plot location. The location can then be entered

on a GIS, and the inventory data for that plot

can be related to other data for that particular

location.

Risk Rating

Monitoring susceptibility, or risk to disturbance agents, is another way of monitoring forest health. Using stand examination data from

site visits, inventory data, aerial photography,

and knowledge of forest conditions conducive

to insects, disease, and fire, forested areas can

be assigned a rating of current risk to a particular disturbance agent. Over time, risk can

change through "natural" maturing of the forest, removal of some trees by a disturbance,

or management activities such as thinning,

prescribed fire, or harvest. Subsequent risk

ratings using updated information can show

these changes in risk. Several computer programs for risk rating stands and watersheds

are being used by National Forests to assist

them in watershed analysis.

CHAPTER 2. DISTURBANCE AND FOREST

HEALTH IN OREGON

OREGON COAST RANGE (M242A)

AND WESTERN CASCADES (M242B)

Ecology

Steep, highly dissected mountain slopes

dominate the topography of the Oregon Coast

and western Cascade Ranges. Because of the

marine influence, the coastal region has the

warmest winters, coolest summers, and greatest rainfall in

Oregon. More than 100 inches

of rain fall on the western slopes

of these ranges; the drier eastern

slopes of the Coast Range average only 30 inches per year. Although July through September

is very dry, fog contributes significant moisture along the coast

and lower western slopes.

Douglas-fir dominates forests

of the Coast Range, extending

from near sea level to about

4,000 feet. A pioneer species

that reproduces after fire or other

disturbances, its long life span

allows it to persist during extended stable periods and reseed an area after a disturbance.

Forests of the lower mountain

slopes and the coastal fog belt are dominated

by Sitka spruce, western hemlock, and western redcedar. Other conifers in the Coast

Range include grand fir, noble fir, Pacific yew,

and lodgepole pine. Red alder is the most

abundant and important deciduous species in

coastal forests.

Low and mid elevations of the western Cascades are dominated by Douglas-fir and western hemlock, with western redcedar, bigleaf

maple, and red alder common in drainage bottoms. As elevation increases, Pacific silver fir,

noble fir, Subalpine fir, mountain hemlock,

lodgepole pine, sugar pine, and Engelmann

spruce increase in importance. Western white

pine is a minor component, and whitebark pine

is common along the crest.

All Species

Fires are infrequent but severe—In the

western Cascades and the Coast Range, the

interval between fires is generally long. When

fires do occur, they are large and severe, kill-

\n the Oregon Coast Range, the most notable fire in recent history

was theTillamook burn, which destroyed 255,000 acres of forest

land in the I 930s. Photo courtesy of the Oregon Historical Society (neg. 55029).
ing most trees, such as in the Tillamook burn

in the 1930s. These large fires are usually associated with drought years and warm dry

winds. Douglas-fir establishes well after intense fires, and many present-day Douglas-fir

forests owe their beginnings to fire. The earliest Douglas-fir plantations were established

after a fire in the Coast Range around 1915.

Wind and root disease cause windthrow—Periodic severe windstorms, typically

between October and March, can cause extensive windthrow. Root disease and stem decay

are the most common biological factors predisposing trees to windthrow. If blown down

trees are Douglas-fir, the Douglas-fir beetle is

likely to attack and kill standing trees for 2

years after a windstorm. During an outbreak,

the beetle typically kills about one live tree for

every three or four that were windthrown. Mortality can be prevented if windthrown trees are

salvaged or beetle repellents used. This interaction of wind, root disease, and bark beetles

creates canopy gaps, mixes soils during tree

uprooting, and increases structural and biological diversity in stands.

The November 1995 windstorm in Oregon

blew down trees on thousands of acres in the

Coast and Cascade ranges. Mortality caused

by Douglas-fir beetle is expected in areas where

trees are not salvaged or protected.

Douglas-Fir

Douglas-fir is plagued by root diseases—

Laminated root rot, a native disease that affects many conifer species, is the most widespread and destructive disease of Douglas-fir

in the Coast Range and western Cascades.

Various surveys estimate that, on average,

patches of laminated root rot occupy 3 to 5%

of the Douglas-fir forest, but the disease is distributed unevenly. Many stands in the northern Coast Range have more than 15% of their

area occupied by root disease patches.

Stem decay—too much or too little? As stands

mature, decay organisms cause tree death or

breakage, creating gaps in the canopy and providing

rotten wood and hollow logs that are used by

wildlife. Although there are benefits to wildlife,

decay and stain can severely reduce timber value.

In managed western Oregon stands, the harvest of

old trees has decreased the average tree age and

amount of decay, especially on private lands. A

concern in areas with extensive young stands may

now be the lack of decay and defect and its probable effect on wildlife and ecosystem processes.

The amount of decay in trees depends on tree

species (some species are more susceptible than

others), and generally increases with the frequency

of wounding, and the size and age of the wound.

The amount of decay in a stand can be reduced by

keeping rotations short and avoiding tree injury

during management activities such as thinning.

Decay can be increased by intentionally damaging trees, retaining defective trees, and

inoculating trees with wood decay fungi. The tradeoff between wood production and

rotten wood for wildlife needs must be balanced through thoughtful long-range planning.

Decay provides habitat for wildlife.
Laminated

Root Rot

Pockets

Laminated root rot creates different-sized openings, as

shown in this map of a 50-year-old Douglas-fir stand in

the Forest Grove District, Oregon Department of Forestry.

Source: Oregon Department of Forestry survey.

Laminated root rot causes tree mortality and

growth loss; it also predisposes trees to

windthrow. Because the disease spreads from

root to root and affects groups of trees, it commonly creates canopy openings of various

shapes and sizes. These openings allow light

to penetrate to the understory, stimulating

growth of herbs, shrubs, and tree species resistant to the disease. Trees killed by the disease provide short-term snags and

logs, which benefit many wildlife species. The increased diversity and benefits to wildlife partially offset the huge

volumes of timber lost to this disease

annually.

Laminated root rot intensifies on a

site when Douglas-fir or another

highly susceptible species are planted

in an infested area and the fungus,

which survives for decades in buried

roots, grows from infected roots onto

the roots of the newly established tree.

Some of the most severe damage is in

the Coast Range, where diseased

stands were burned or clearcut and

planted with Douglas-fir. Current

management emphasizes planting or

retaining resistant or immune species

and carefully designing silvicultural

systems to prevent blowdown after

thinning.

Armillaria and black stain root diseases are far less abundant and damaging than laminated root rot but occasionally cause significant damage in

young Douglas-fir plantations, particularly those stressed by poor planting or soil compaction. Both diseases

are often found on the edges of laminated root rot patches.

Swiss needle cast damages

coastal Douglas-fir—Swiss needle

cast is a native foliage disease of Douglas-fir throughout the Coast Range

and western Cascades. It impairs the

tree's ability to regulate water loss and

causes premature loss of needles. Severely damaged trees grow poorly and

may die.

In most areas, the disease is of little consequence, causing premature shedding of 3- and

4-year-old needles. Since the early 1980s,

however, thousands of acres of Douglas-fir

plantations along the north coast have shown

increasingly severe damage from this disease.

In late winter and early spring, diseased plantations are noticeably yellow to brownish yel-
Swiss needle cast has become increasingly severe during the last decade

along the north Oregon coast Diseased stands appear yellow and grow

poorly (left) compared to healthy stands (right).

Trees with Swiss needle cast may lose all but the current year's needles

(left), in contrast to healthy branch (right). With so little foliage

remaining for photosynthesis, tree growth declines and some trees die.

low, in contrast to adjacent natural stands that

are green and vigorous. Most plantations with

severe symptoms are 10 to 25 years old and

within 15 miles of the coast in the fog zone.

Much of this area was previously dominated

by hemlock, spruce, or western redcedar. Why

this native disease has become so severe in this

area remains unclear.

The severity of symptoms differs considerably

among individuals in the

Douglas-fir population,

indicating that tolerance

exists within the species.

The current management

recommendation for

areas with moderate or

severe damage is to favor

species other than Douglas-fir whenever possible. If Douglas-fir is

planted, seed should be

from parent trees that

performed well in the

coastal fog zone.

Black bears injure

and kill young Douglas-Jir—Black bears peel

and eat the inner bark of

young conifers, especially

Douglas-fir, in spring

when the inner bark is

succulent and sugar content high. When the entire circumference of the

bole is peeled, the tree

dies. Partial peeling can

reduce tree growth and

vigor, and provide an

entry point for organisms

that decay the valuable

butt log. An Oregon Department of Forestry

study of Coast Range

bear damage found that

for every tree with its

entire circumference

peeled, at least two other trees were partially

peeled.

Bear damage is common in Douglas-fir

stands in the 16- to 25-year age class, often

soon after the stands have been thinned. In

these stands, bears prefer the most vigorous

and largest diameter trees. Although bears

damage trees throughout the Coast Range and
Black bears peel and eat the sweet, succulent

inner bark of young Douglas-fir in the spring.

Bear-killed trees occur on about 40,000 acres

annually in western Oregon.

A survey of bear-damaged Douglas-fir in western

Oregon found about one-third of the damaged

trees were completely girdled and destined to die.

Those girdled 76 to 99% are also likely to die.

Source: Oregon Department of Forestry survey.

western Cascades, damage intensity differs

considerably from one area to another. Surveys since 1988 do not show a clear trend of

increasing or decreasing damage. Damage in

some areas is severe enough to warrant bear

management programs.

Various Species

Western hemlock, Sitka spruce, and

western white pine are affected by several

insects and diseases—In northwest Oregon,

western hemlock is host to annosus root disease, hemlock dwarf mistletoe, and hemlock

sawfly and looper. Sitka spruce weevil is an

important pest of Sitka spruce regeneration in

Hemlock dwarf mistletoe causes witches brooms,

deforms branches, and decreases tree growth.

Some wildlife species, such as the marbled

murrelet, nest in branches deformed by dwarf

mistletoe. Photo courtesy of Kim Nelson.

coastal Oregon and has deterred foresters from

regenerating spruce over much of its natural

range. The range and abundance of western

white pine, found mostly in the western Cascades, has been reduced by the introduced disease white pine blister rust. But planting seedlings bred for resistance to the disease, pruning

young trees, and rating sites for hazard is ensuring the continued presence of western white

pine in Northwest forests.
WILLAMETTE VALLEY (242A)

Ecology

The forests of the Willamette Valley are

stands, groves, or savannas of Douglas-fir and

Oregon white oak, with scattered ponderosa

pine. Western hemlock, grand fir, and western redcedar grow on the wetter sites, as do

bigleaf maple, black cottonwood, red alder, and

Oregon ash. Most of the land lies between 50

and 1,000 feet in elevation, with a few hilltops

on the eastern edge reaching 1,500 feet. The

summers are hot and dry; annual precipitation ranges from 25 to 60 inches, most of it

between October and June.

Although the Willamette Valley is characterized by a summer drought, weather records

show that the severity of drought fluctuates in

10- to 20-year cycles. The mid 1980s to the

early 1990s was generally drier than normal,

and the next 10 to 20 years are predicted to

be wetter than normal.

All Species

Lack of jire has caused species shifts in

the Valley—Historically, fire was periodic in

the Willamette Valley, either started naturally

or set by people to maintain open areas. Frequent, light, ground fires maintained oak and

pine stands because the large thick-barked

trees tolerated fire better than did young oaks,

grand fir, or Douglas-fir. In the last century,

fire has been excluded, and many oak stands

are now losing the competitive race with Douglas-fir and other species. Without the return

of fire, and with increased urbanization and

agriculture, oak and pine stands will likely diminish slowly in the Willamette Valley.

Air pollution increases with increasing

people—The population of the Willamette Valley has greatly increased over the past few decades, mostly in the Portland area. Future

projections are for continued growth. Population growth will be accompanied by increased

pollution from automobiles and light and heavy

industry. Air pollution not only affects visibility and human health, but also damages forests.

Ozone is a pollutant that affects forests.

Monitoring of both vegetation and air has

shown that ozone concentrations in some areas are high enough to cause plant damage.

In the Willamette Valley, the number of lichen

species, which are more sensitive to ozone than

other plants, has decreased in some areas. The

number and diversity of lichens, as well as the

concentration of pollutants in lichen tissue, are

being monitored to identify forested areas with

ozone damage.

Drought interacts with insects and diseases to damage conifers—The sudden apIn the Willamette Valley, wet and dry periods have

fluctuated in 10- to 20-year cycles during the last

century; 1985 to 1994 was a period of drought

Source: Surface Water Supply Index, Natural Resources Conservation Service.
pearance in spring or early summer of dead

lateral branches, dead tops, or entire dead

trees (particularly Douglas-fir) can be alarming. The primary cause of damage is water

stress in the tree resulting from drought in the

previous year or accumulated over several

years. The water stress reduces the tree's ability to defend itself against insects and pathogens. Damaged trees are most common in

urban areas on the fringe of forested areas, in

overstocked stands, on compacted or disturbed

soils, and on droughty or shallow soil types.

Such damage was particularly noticeable during the late 1980s and early 1990s, a period

of drought in the Willamette Valley. Similar

observations were documented in the 1950s

and the 1970s.

Winter weather kills needles or tree

tops—Winter drying of needles is common on

Douglas-fir in the northern end of the

Willamette Valley and in the Columbia Gorge,

where dry, easterly winds and sunny weather

cause water loss from needles to exceed water

uptake by roots. Needles often dry out and fall

from the tree in late winter and early spring.

Although the damage is highly visible, the buds

usually are not damaged and new growth resumes in spring.

Low temperatures alone can kill needles,

buds, twigs, or inner bark. Large trees, particularly Douglas-fir and ponderosa pine, are

often topkilled when low temperatures follow

an unseasonably warm period. In the November 1955 "deep freeze," and again to a lesser

extent in the winter of 1985,

widespread topkill was reported throughout the

v , Willamette Valley. Mortality

and other symptoms of low

temperature injury often do

not show up until one or two

growing seasons after injury.

Douglas-fir on droughty soils show typical symptoms of

canker diseases after a very dry year.

Symptoms of Moisture Stress. Trees respond to moisture stress in several ways. Under moderate stress, stem

and root growth are reduced. As stress increases, trees

become increasingly susceptible to certain insects and

diseases, particularly canker diseases and twig beetles.

Under severe drought, water content in the tree may drop

so low that the entire tree or portions of it may die. Roots

and the lower main trunk are the last to die, and often

remain living even though aboveground parts are dead.

Sudden low temperatures after

a warm period in winter can kill

the tops of large, exposed trees,

especially Douglas-fir.
Oregon white oak in late summer can be

completely stripped of foliage by the oak

looper.

Oregon White Oak

Oregon white oak is

threatened by development and fire exclusion—Oregon white oaks

are one of the hallmarks

of the Willamette Valley. They are ecologically im- portant as food for many

wildlife species, espe- cially acorn woodpeckers

and wild turkeys. In ad- dition to threats from ag- riculture, urbanization, and exclusion of fire, white oak is host to a

plethora of insects and

diseases; fortunately, few

threaten its survival.

The most visible and periodically damaging

insect is the western oak looper, which defoli- ates trees over large areas. The present out- break has persisted for at least the last 5 years. Populations of this insect near the Dallas area

have been so high during the past 4 years that

the loopers have defoliated the tops of other

hardwoods and Douglas-fir growing in asso- ciation with the oak.

Armillaria root disease attacks Oregon white

oak and is often associated with tree uproot- ing in urban areas. White oak is adapted to

droughty summers, and summer irrigation in

urban areas and parks seems to contribute to

the development of armillaria root disease.

Ponderosa Pine

Native pine is disappearing from the

Willamette Valley—Ponderosa pine was once

abundant in the southern part of the

Willamette Valley, but urbanization, logging, and fire exclusion have diminished its popu- lation to small scattered patches of trees, es- pecially in the northern part of the Valley. Natural regeneration has decreased, primarily

because fire no longer creates seedbeds and

removes competing understory vegetation.

Genetically different from eastern Oregon

Ponderosa pine, Willamette Valley ponderosa

pine has few major pests

when grown in the Valley. The ponderosa pine cone

beetle attacks young

cones and compromises

natural regeneration. In

larger trees, pine bark

beetles can attack and

kill moisture-stressed

pines, particularly in

drought years and in

overstocked stands. Fo- liage diseases periodi- cally plague eastern Or- egon ponderosa pine

planted west of the Cas- cade Range, especially in

areas with persistent fog.

Grand Fir

Exotic insect damages grand fir—The

balsam woolly adelgid is a minute aphid-like

insect that sucks sap from true fir trees and

excretes a waxy "wool" that gives it its name. Introduced to the west coast early this century, this often overlooked pest has tremendous ef- fect on the growth and seed production of

grand fir and likely is responsible for decreases

in grand fir populations at low elevations in the

Willamette Valley.

Hybrid Poplar

Poplar is host to a recently introduced

foliage disease—Since 1980, commercial hy- brid poplar plantations have rapidly expanded

in the northern Willamette Valley and along the

Columbia River in Oregon and Washington. In

1991, two new species of melarnpsora leaf rust

were reported from plantations near

Scappoose, Oregon, and Woodland, Washing- ton. These particular rusts are considered the

most economically important poplar leaf rusts

in the world. As of 1995, one of these rusts

has become established in the Pacific North- west, and the other (Eurasian poplar leaf rust)

has not. Hybrid poplar clones resistant to

these and other diseases are being developed

continually.
EASTERN CASCADES (M242C), MODOC PLATEAU (M26IG),AND

BLUE MOUNTAINS (M332G)

Ecology

The Eastern Cascades and Modoc Plateau—This region comprises the eastern

slopes of the Cascade Range and the dry volcanic area at the southern end of the eastern

Cascades. The eastern Cascades include several high volcanic peaks: Mount Hood, Mount

Jefferson, and the Three Sisters, all with

elevations over 10,000 feet.

The mixed conifer forests of this area are

very complex and variable in terms of species

composition and structure. Typically, mixed

conifer stands on moist sites are characterized

by a sparse overstory of large ponderosa pines

and Douglas-firs, and a dense understory composed primarily of true firs with fewer lodgepole pine, occasional western larch, and western white pine. Historically, these stands were

predominantly pine, maintained by frequent,

low-intensity ground fires.

On dry sites, the structure and species composition are simpler, normally consisting of

only two species (white fir and ponderosa pine)

in a distinctly two-storied arrangement with

large pines in the overstory. The most common pine species in this area are ponderosa

and lodgepole. Each species covers a large area

where it is the dominant climax species. Less

common are the five-needled pines, including

western white and sugar pines.

The Blue Mountains—Two major mountain ranges dominate the Blue Mountains region, the Blue Mountains in the center and

southwest and the Wallowa Mountains in the

northeast. Wide, low valleys separate the

mountain ranges and channel two major rivers, the John Day and the Grande Ronde. The

eastern boundary of this region follows the

Snake River through Hells Canyon, separating Oregon and Idaho. Elevations range from

1,000 to 10,000 feet.

Conifer forests are the dominant vegetation

at middle elevations in the Blue Mountains.

The forests range from spruce and fir at higher

elevations to mixed conifers (grand fir, Douglasfir, lodgepole pine, western larch, and ponderosa pine) at mid elevations to ponderosa pine

at lower elevations. Important hardwood species, such as black cottonwood, quaking aspen, and willow, as well as many rare, endemic

plant species, are concentrated in wetlands

and riparian areas. Fire frequency once determined the composition of low and mid

elevation forests in the Blue Mountains. Decades of fire suppression and selective logging

of seral conifers (such as ponderosa pine and

larch) have created forests that are more susceptible to disturbances from insects, diseases,

and stand-replacing fires.

All Species

Drought, wind, and severe winters injure

trees—Precipitation patterns are a key driving force for determining the character of the

forested vegetation on the east side of the Cascade Range and the Blue Mountains. Moisture, falling as rain or snow in the spring and

fall, is abundant at upper elevations but decreases rapidly with decreasing elevation.

Summers are usually very dry throughout the

area, especially at the lower elevations.

Various weather-related events common to

this area are important to forest health. Periodic droughts reduce the capacity of trees to

protect themselves against insects such as

bark beetles and defoliators; large-scale outbreaks often occur during dry periods. Dry

years from the mid to late 1980s to the mid

1990s contributed to widespread tree mortal-
The last 10 to 12 years have been drier than

average in eastern Oregon. In this drought index

for the Blue Mountains, below zero represents

drier than average years, and above zero is

wette r than average. Source:SurfaceWater Supply Index,

Natural Resources Conservation Service.

ity on dry sites, particularly where stands were

overstocked. Windstorms can cause stem

breakage and windthrow, which increases

stem decay in wounded trees and leads to bark

beetle buildup in windthrown trees. In the

Blue Mountains, severe winter storms often

cause extensive snow breakage or windthrow

in localized areas. Floods and ice jams frequently damage trees growing in riparian zones

or on flood plains.

Fire suppression changes forests—Natural

fire has played an important role in mixed conifer and ponderosa pine forests. In the lowelevation mixed pine and fir forests, frequent

low-intensity fires maintained stands at low

tree densities. At higher elevations, fires were

less frequent but of higher intensity, often leading to removal of the entire stand. With the

suppression of the low-intensity ground fires,

stands have become extremely dense and now

contain a large proportion of species such as

true firs that are particularly susceptible to

insects, diseases, and stand-replacing fires.

Dwarf mistletoe is more severe where fire

is suppressed—Many conifer species east of

the Cascades are infected by dwarf mistletoes,

which are plant parasites. Before the 1900s,

fires were frequent and reduced or eliminated

dwarf mistletoe in many stands in the eastern

Cascades and the Blue Mountains. For most

tree species, fire suppression in the past century has resulted in more severe mistletoe infections, particularly when stands are

unmanaged.

In the eastern Cascades and on the Modoc

Plateau, Douglas-fir dwarf mistletoe is the most

pervasive and damaging. Western larch also

has high rates of mistletoe infection, despite

the distances between host trees on stands.

True firs, too, are affected by a dwarf mistletoe, but the effects on tree health are far less

intense than in Douglas-fir and western larch.

The combination of mistletoe infection and an

opportunistic canker fungus often kills branch

tips and produces a conspicuous flagging in

infected true firs.

In the Blue Mountains, crown deterioration

from dwarf mistletoe is the most important

cause of western larch mortality in undisMore than 40% of the Douglas-fir in eastern

Oregon are infected with dwarf mistletoe, which

causes growth loss, topkill, and mortality. Note

the prominent brooms on the tree in the foreground and the killed tops on the trees in the

background.
turbed areas, where 38 to 51% of the larch in

a stand might be infected. Where larch stands

are managed, the removal of badly infected

trees can reduce the amount of infection and

increase vigor of the whole stand. Dwarf

mistletoe is also common in Douglas-fir, ponderosa pine, and lodgepole pine. In pine, the

most severe mistletoe infections tend to be in

stands with a high proportion of pine and infrequent-fire histories.

Mixed Conifers

Western spruce budworm population collapses in mixed conifer stands—The most

significant and persistent defoliating insect in

eastern Oregon has been the western spruce

budworm. Between 1980 and 1992, more than

400,000 acres of host type in central Oregon

and more than four million acres in the Blue

Mountains were affected by the budworm. This

outbreak coincided with a drought that affected most of eastern Oregon. Douglas-firs,

grand firs, and white firs were repeatedly defoliated at various intensities on the Ochoco,

Deschutes, Wallowa-Whitman, Umatilla, and

Malheur National Forests. Some of the defoliation effects included topkill, tree mortality,

reduced growth, elimination of cone crops, and

reduced resistance to other agents of mortality such as root diseases and bark beetles. In

the most extreme cases (where the susceptible

host type was most abundant), around 80%

of the trees died. Spruce budworm populations collapsed region wide in 1992, and very

little current defoliation is evident in this part

of Oregon.

Bark beetles benefiting from crowding

and drought—Several bark beetles have been

important in eastern Oregon mixed conifer forests in the past decade: fir engraver, Douglasfir beetle, and western pine beetle. These insects are opportunistic and usually benefit

from stress on the host tree resulting from

crowding, disease, defoliation, or drought. Oldgrowth set-aside stands, where management

activities are restricted, suffered high tree

mortality. An unprecedented amount of fuels

from insect-killed trees has accumulated during the last decade. The abundance of overstocked, low vigor, mixed conifer stands in

eastern Oregon makes a repeat of the massive

tree mortality in the 1980s an eventual certainty.

One of the most conspicuous vegetation

changes in southeastern Oregon was the

massive white fir mortality in Lake and KlaWestern spruce budworm defoliation was

apparent on almost all lands where the host

species grew between 1980 and 1992.

Source: Cooperative Aerial Survey, Oregon Department of Forestry and

USDA Forest Service.

The number of acres affected by western spruce

budworm in eastern Oregon peaked in 1986.

Source: Cooperative Aerial Survey, Oregon Department of Forestry and

USDA Forest Service.
Mortality from the fir engraver soared in 1995;

overstocking and drought are the underlying

causes. Source: Cooperative Aerial Survey, Oregon Department of

Forestry and USDA Forest Service.

math counties. The cause is a fir engraver

outbreak after several years of below-average precipitation. Much of the mortality was

in overstocked stands at elevations below

6,000 feet. Before fire-suppression programs, most of these sites

were dominated by ponderosa pine stands. A similar

pattern of white fir mortality

is affecting areas of northern

California. Because few of

the dead trees have been salvaged, the potential for catastrophic fire in Oregon remains high.

The Douglas-fir beetle

killed thousands of trees in

recent years, especially in

areas where the host trees

sustained heavy budworm

defoliation. After the spruce

budworm outbreak, these

bark beetles have attacked

and killed many of the trees

weakened by several years of

defoliation and drought.

Characteristically, DouglasArmillaria root disease is the

key disturbance agent in many

mixed conifer stands. Trees

weakened by soil compaction,

drought, and overcrowding are

very susceptible to armillaria.

fir beetles select the largest trees in the stand

and thus have profound effects on stand

structure. These effects have been most

notable in recent years on the Sisters Ranger

District (Deschutes National Forest), the

Warm Springs Indian Reservation in the

eastern Cascades, and the Malheur,

Umatilla, and Wallowa-Whitman National

Forests in the Blue Mountains.

Shifts in tree species cause increased

root disease—Root diseases cause subtle,

but persistent growth loss and mortality in

mixed conifer stands. When disease pockets are small and scattered, they often increase the structural diversity and benefit

wildlife and understory plants. Large rootdisease pockets in areas designated for timber management cause significant economic

loss and increase fuel loading.

Root disease has increased in mixed conifer stands as host species have increased.

Fire exclusion has resulted in less pine and

larch, species more resistant to root diseases, and greater numbers of the more susceptible Douglas-fir and true fir. Partial cutting of mature trees in root disease areas, a

common management practice, can intensify

root disease problems. Root

disease fungi colonize the

roots and stumps of cut trees

and then spread to live trees.

Partial cutting also results in

natural regeneration of susceptible species in the diseased area. Disease centers

will remain a problem in

managed mixed conifer

stands until the use of fire or

other silvicultural treatments promote the regeneration of resistant seral species

such as pine and larch. Increases in the proportion of

true fir and Douglas-fir in

mixed conifer stands have

led to increases in armillaria

and annosus root diseases

and laminated root rot.
Western Larch

The greatest threat to western larch is

the lack, of forest disturbance—Fire suppression and partial cutting maintain forest

floor conditions that prevent larch from successfully regenerating. In the absence of disturbance, larch stands are gradually taken

over by species more shade-tolerant than larch,

such as grand fir and Douglas-fir. Only the

re-introduction of fire or periodic mechanical

disturbance can create the proper seedbed for

larch. Furthermore, larch seed crops are usually poor because of dwarf mistletoe infections,

frost damage to conelets, and feeding by western spruce budworm.

Seed production is thus

inadequate for either

natural regeneration or

nursery-grown seedlings.

Pines

Distribution of pine

is affected by fire—Ponderosa pine once covered

large areas of the Blue

Mountains and the eastern Cascades that are

now mixed conifer forests. Disturbance from

fire played a crucial role

in maintaining the dominance of ponderosa pine

and stand health by reducing tree densities.

Fire suppression in pine

stands results in higher

densities, reduced tree

vigor, and greater susceptibility to bark beetles,

particularly in places

where pine forests intergrade with desert, like

the southern flank of the

Blue Mountains. Lodgepole pine is an important

seral species that colonizes disturbed sites in

the grand fir zone in the

Blue Mountains and frost

prone areas in central

Oregon. Although it is an aggressive colonizer,

it can be replaced by shade-tolerant species

such as grand fir in the absence of fire. In areas dominated by lodgepole pine but with infrequent fire, dwarf mistletoe has a significant

effect on stand vigor.

Mountain pine beetle is still evident in

lodgepole pine—In eastern Oregon, the most

conspicuous incidence of bark beetle activity

in pines has been mountain pine beetle in

lodgepole pine. Although outbreaks of this

species are infrequent—every 60 years—they

always kill the largest trees in the stand and

produce enormous quantities of fuel. In cenOld ponderosa pine is killed by pine beetles. Western and mountain pine beetles have been important

mortality agents of ponderosa pine in pine and mixed

conifer stands, in connection with drought and high

stand densities resulting from the suppression of natural

fires. On the Fremont National Forest, more than 14,000

large pines were killed in 1992, and another 18,000 in

1994. Throughout eastern Oregon, losses have been

significant because old, yellow-barked pines are underrepresented across the forested landscape and the "oldgrowth" character of mixed conifer stands is drastically

altered by the loss of larger overstory trees.
Cottonwood and aspen groves are disappearing. Two shade-intolerant hardwoods,

quaking aspen and black cottonwood, have declined as a result of cattle and sheep

grazing, an increase in big game, exclusion of natural fires, and encroachment of conifers.

Regeneration of aspen requires fire to stimulate sprouting from roots and to eliminate

competition from conifers. Cottonwood depends on flooding to control competing vegetation and prepare suitable seed beds for regeneration; it also sprouts from roots after fire.

These hardwoods are extremely important in riparian communities. They provide streamside stability, shading, water temperature regulation, and wildlife habitat. Although not

abundant, quaking aspen is an important component of the eastern Oregon landscape.

Over the past century, the extent of aspen stands has declined in central Oregon alone by

about 50%.

tral Oregon, an areawide infestation in the

1980s, covering more than 500,000 acres, killed virtually all trees more than 8 inches in

diameter in pure stands of lodgepole. This out- break ended in 1989, although some areas, on

about 50,000 acres along the Cascade Lakes

Highway near Bend, are still experiencing sig- nificant mortality in lodgepole pine.

In the Blue Mountains, the last major out- break of mountain pine beetle was in the

1970s, affecting almost one million acres. Al- though mountain pine beetle mortality has

decreased since the 1970s outbreak, lodgepole

stands will again stagnate and set the stage

for another beetle outbreak unless active man- agement is initiated to control tree densities.

Various Species

Some insects and diseases are of local or

diminishing importance. Root diseases

(annosus, black stain, and armillaria) are locally

important on ponderosa pine in eastern Oregon. Engelmann spruce, important in riparian

stands, is often infected by tomentosus root and

butt rot, which makes it susceptible to

windthrow and spruce beetle attacks after wind- storms. The Douglas-fir tussock moth outbreak

that peaked in 1993, affecting 46,000 acres in

the Blue Mountains, subsided in 1995. Simi- larly, the pandora moth outbreak on lodgepole

and ponderosa pine in central Oregon peaked

in 1994 and has collapsed in 1996.

Aspen groves that have been burned (left) can successfully regenerate by sprouting from roots of

burned, killed trees. Aspen declines and other species encroach where fire is suppressed (right).

Artwork by Beverly Swanson.
SOUTHERN CASCADES (M26ID)

AND KLAMATH MOUNTAINS

(M26IA)

Ecology

Southwestern Oregon is one of the most diverse regions in the United States. Geology and

soils are extremely varied. Elements of the

California, north coast, and eastern Oregon floras combine with many species indigenous

only to the Klamath Mountain region. During

periods of climate change, plants from as far

south as Mexico and as far north as the Arctic

established in the area and mixed with endemic species. Plants and animals continue

to migrate north and south along the Cascade/

Sierra and Coast ranges and east and west

across links in the ranges. Species such as

mountain mahogany, sagebrush, and quaking

aspen reflect the area's importance as an eastwest axis, and Pacific silver fir and Alaska

yellow-cedar reflect north-south movement.

Sierran pine and shrub species are also common. The area has been the site of local development of ancient conifers including yew,

cypress, and redwood.

Forest vegetation in interior valleys of the

Rogue and Umpqua rivers and lower elevations

of the Cascade Range and the Siskiyou Mountains includes drought-tolerant conifers and

hardwoods such as ponderosa and sugar

pines, California black and Oregon white oaks,

and Pacific madrone. Mid elevations include

Douglas-fir, white fir, tanoak, and chinkapin.

Higher elevations are dominated by true firs

and mountain hemlock. The Siskiyou Mountains also contain large areas of soils that support Jeffrey pine, Port-Orford-cedar, and

unique associated flora.

Southwestern Oregon has a mediterranean

climate, with generally mild, wet winters and

warm, dry summers. Most precipitation is

from November to March. Summer thunderstorms are common. Annual precipitation

ranges from slightly less than 20 inches in interior valleys to 120 inches at higher elevations.

The late 1980s and early 1990s was a period

of below-average rainfall. The area has the

greatest temperature extremes in western Oregon. In summer, it is often the warmest part

of the state.

Southwestern Oregon has experienced a drought

over the past decade. This drought index graph

shows years that are drier than average (below

zero) and years that are wetter than average

(above zero). Source:SurfaceWater Supply Index, Natural

Resources Conservation Service.

All Species

Past and present fires influence vegetation—Historically, fire has played a critical role

in shaping vegetation. At low to mid elevations,

frequent, low-intensity ground fires were once

common. Fire frequencies ranged from 15 to

50 years in the Klamath Mountains. In interior valleys, the fire-return interval was prob-
Root diseases (such as laminated root rot

pictured above) are often overlooked because of

the subtle nature of their effects; however, their

long-term effect on growth and survival is much

larger than that of virtually any other forest

mortality agent

Dwarf Mistletoes. Dwarf mistletoes

are parasitic plants that infect conifer

species. Small, sticky seeds are forcibly

discharged from female dwarf mistletoe

plants and land on conifer needles.

They are washed down to the branches

where they germinate, invade the tree

tissue, and draw water and nutrients

from the host plant. Infection is favored

by multilayered canopies of single

species. Most dwarf mistletoes are

highly host specific, infecting only one or

a few tree species. Their effects on their

hosts include growth loss, topkill, distortion, mortality, and predisposition to

infection and attack by other agents

such as bark beetles or decay fungi

Dwarf mistletoe brooms are often occupied by nesting birds and small mammals. Managing dwarf mistletoe to

provide wildlife habitat without sacrificing the vigor of the stand poses challenges for landowners and managers.

Mistletoes will continue to be aggressively managed where heavily infected

trees pose threats to human safety or

where timber values are of primary

importance.

ably 8 to 10 years, resulting in a pine-domi- nated forest with few snags and little woody

material on the forest floor. In recent decades, the fire regime has shifted toward infrequent

high-intensity, stand-replacing fires. Fire ex- clusion has resulted in substantial increases

in stand densities and higher proportions of

less fire-tolerant species. At high elevations, infrequent, low- to moderate-intensity ground

fires were common historically. Now, high-in- tensity, stand-replacing fires are more com- mon.

Root diseases hove subtle but significant

effects on growth and survival—Several

native fungi cause root diseases in southwest- ern Oregon. Of particular importance are lami- nated root rot, armillaria, and black stain root

diseases. Most root diseases are diseases of

the site. Inoculum of laminated and armillaria

root diseases may remain viable in the wood

of infected roots for 20 to 50 years. They cause

growth loss and mortality in individual trees. Across the landscape, root diseases produce

changes in forest species composition and

structural diversity. They create canopy open- ings, alter vegetative succession, provide snags

for cavity nesters and their associates, and

contribute woody material to the forest floor

and streams. Root diseases are managed by

favoring resistant and immune species adapted

to sites and by encouraging harvest practices

that avoid reducing the vigor of individual

trees.

Dwarf mistletoes are more abundant

now—Dwarf mistletoes are distributed widely

in southwest Oregon, especially on the east

side of the Siskiyous and in the Cascades.

CONTINUED
They are common on

Douglas-fir, white fir,

lodgepole pine, Jeffrey

pine, western hemlock,

and mountain hemlock

and less frequent on ponderosa pine and other

species.

Trees infected with

dwarf mistletoes have

been removed during

timber harvest and stand

cleaning in some portions

of the region. Many areas, however, probably

have more dwarf mistletoe-infected trees now

than they had before fire

exclusion. Where ground

fires were once frequent,

higher proportions of infected trees were killed

because ground fuels

and large brooms carried

fire into the crowns. In

many areas with selective

harvests, healthy trees

were removed, leaving

behind infected trees, or

heavily infected trees

were removed and infection intensified in lightly

infected trees when those

Port-Orford-cedar (green) and Port-Orford-cedar root disease (red) have

been mapped on the Siskiyou National Forest. The disease is found in

wet areas along streams and in riparian areas. Source: USDA Forest Service surveys.

trees were exposed to increased light.

Port-Orford-Cedar

Exotic pest kills Port-Orford-cedar on wet

sites—Port-Orford-cedar grows from just north

of Coos Bay, Oregon, into northern California

in a narrow coastal strip. It grows on a wide

variety of sites including streambanks, bogs,

coastal sand dunes, deep productive soils, and

dry sites. Port-Orford-cedar needs a consistent water supply and is an important species

in riparian ecosystems. Its snags and logs are

long-lived components of terrestrial and

aquatic wildlife habitat. It has important cultural value to the indigenous people of northwestern California. Although its domestic

market is limited, for decades the export market for Port-Orford-cedar has been substantial, making it one of the most valuable species in North America.

In 1952, an introduced disease caused by

a waterborne fungus, was reported within

the native range of Port-Orford-cedar at Coos

Bay, Oregon. Cedar mortality soon became

conspicuous in coastal towns and along major roads. The fungus is now present

throughout much of the range of PortOrford-cedar. Infested and healthy Port

Orford-cedar are intermingled. Where the

disease has been present for several decades,
Port-Orford-cedar killed by Port-Orford<edar root disease is common

along roads where the disease-causing fungus is spread in soil by

vehicles and road construction.

mortality has been extensive, especially

along streams and downslope drainage

ditches. Mortality is less and often absent

on drier microsites. An interagency and interregional coordinating

group provides technical

assistance on Port-Orfordcedar management for federal agencies.

Some of the strategies for

controlling Port-Orford-cedar

root disease include the following:

• Close roads and restrict

operations to reduce movement of infested soil.

• Clean vehicles and equipment before entering or

leaving specified areas to

remove soil that may contain spores.

• Berm roadsides to reduce

splash and runoff.

• Remove Port-Orford-cedar from roadsides to

prevent infestation of disease-free stands.

• Identify resistant trees

and breed them for resistance to the fungus.

• Retain Port-Orford-cedar in portions of stands

where conditions are unfavorable for the disease.

Five-Needle Pines

Bark beetles and

blister rust are killing

five-needle pines—

Five-needle pines, including sugar pine,

western white pine,

and whitebark pine, are

declining throughout

southwestern Oregon.

Mountain pine beetles

are killing large fiveneedle pines, especially those stressed by injury, disease, or intense competition. Recent

high rates of beetle-caused pine mortality are

due mainly to overly dense stocking caused

by fire suppression, compounded by the recent decade of drought.

White pine blister rust affects all five-needle pines,

causing topkill, branch mortality, and tree death. The

disease has been in southwestern Oregon since the

mid 1920s and many sites

are conducive to infection

because moisture, as clouds

or fog, in the late summer

and early fall allows rust

spores to germinate and infect pines. Rates of infection

and subsequent mortality

are high in pine regeneration,

and large infected trees are

more vulnerable to bark

beetle attack.
Five-needle pines are

important trees in southwestern Oregon. Western white pine and sugar

pine are valuable because of their fast

growth, ability to reach

great ages and sizes, frost

hardiness, and resistance to root disease. All

three species have high

scenic, wildlife, and watershed values. They

contribute significantly

to ecological diversity. In

the absence of blister

rust and mountain pine

beetle, these pines thrive.

Losses of five-needle pines has

been greatest in southwestern

Oregon between 1988 and 1991,

a period of severe drought

Source: Cooperative Aerial Survey, Oregon

Department of Forestry and USDA Forest Service. Mixed Conifers

Bark beetle mortality is highest on dry,

overstocked sites—Ponderosa pine, Douglasfir, and white fir mortality from bark beetles

was particularly high in 1995, especially on

dry, overstocked sites. Currently, drought and

insects are replacing fire as primary regulators

of site stocking. Such uncontrolled disturbances have serious drawbacks. For example,

large ponderosa pines tend to be the first trees

killed by bark beetles; such large trees are often important to meet management objectives.

Extensive insect-caused tree mortality, particularly in multilayered stands, can create

massive fuel buildups, which ultimately can

contribute to large-scale, severe wildfires.

Landscape-scale assessment is becoming increasingly common for addressing drought-related mortality issues. Density-management

projects are planned or underway in many overstocked stands. Treatments include thinning,

prescribed burning, or a combination of the two.

Treatment priorities are assigned by risk-rating

systems that take into consideration stocking,

elevation, proximity of insect activity, the urbanforest interface, and fire regimes.

bark beetle mortality in southwestern Oregon has been high

since the late 1980s. The prevalence of dense stands over extensive areas and a succession

of extremely dry years have predisposed trees to insect attack.

Source: Cooperative Aerial Survey, Oregon

Department of Forestry and USDA Forest Service.

Locations of bark beetle mortality in all tree

species on the Rogue River National Forest and

Bureau of Land Management's Medford District

in 1995 . Source: Cooperative Aerial Survey, Oregon Department of

Forestry and USDA Forest Service.

CHAPTER 3. DISTURBANCE AND FOREST

HEALTH IN WASHINGTON

WASHINGTON COAST RANGE

(M242A),WESTERN CASCADES

(M242B),AND PUGETTROUGH

(242A)

Ecology

Washington Coast Range—The Washington Coast Range extends from the Olympic

Mountains in the north southwards into Oregon. The Olympics, in the center of the Olympic Peninsula, are unusually high, with elevations up to 8,000 feet; many of the major peaks

have active glaciers. Most other peaks are below 4,000 feet. Flat, coastal lowlands are extensive in some areas. Dunes and bogs are

frequent along the coast, interspersed with

headlands of more resistant rock.

Douglas-fir, western hemlock, Pacific silver

fir, and western redcedar predominate on the

higher mountain slopes. Forests of the lower

slopes and the coastal fog belt are dominated

by Sitka spruce and western hemlock. Precipitation is heaviest from November to April

and averages 60 to 240 inches annually, some

of the highest rainfall in the state. Severe winter storms cause landslides and windthrow.

Stand-replacing fires burn at irregular intervals of 90 to 250 years.

The Puget Trough—The Puget Trough is

the northern extension of Oregon's Willamette

Valley. In the north, glacial activity has shaped

the land and influenced soil composition. Elevation ranges from sea level to 2,000 feet. The

dominant vegetation in this region is western

redcedar, western hemlock, and Douglas-fir.

Riparian species include cottonwood, willow,

red alder, and bigleaf maple. Precipitation averages less than in the Coast Range, from 25

to 60 inches, although intense winter storms

caused flooding at frequent intervals before

dams were built.

Fires were commonly set by American Indians, trappers, hunters, and settlers. Early fires

created and maintained prairies that stretched—

intermingled with forests—from Tacoma to the

Columbia River. Today, many of the original

prairies have converted to forests.

The Western Cascades—The western Cascades region consists of steep mountain slopes,

highly dissected by large rivers. Elevation

ranges from near sea level at the Columbia

River to higher than 14,000 feet at the peaks

of the Cascade Range, although most of the

region is between 2,000 and 7,000 feet. Low

and mid elevations of the western Cascades are

dominated by Douglas-fir and western hemlock, with western redcedar, bigleaf maple, and

red alder common in drainage bottoms. As

elevation increases, mountain hemlock, Subalpine fir, Pacific silver fir, noble fir, and Engelmann spruce increase in abundance. Western white pine is a minor stand component,

and whitebark pine is common along the crest.

Precipitation ranges from 50 to 150 inches,

falling as rain and snow during October to

June. Summers are relatively dry. Fire periodicity is extremely variable, ranging from decades to centuries for major stand-replacing

fires. Volcanos erupt periodically.
Pollution from the Puget Sound region can be seen at Red Mountain, near Mount Adams, more than

10 miles away. Days with little or no pollution (left) contrast with high pollution days (right).

All Species

Air pollution in Puget Sound has longrange effects—The population of western

Washington is expected to increase in the future and, with it, the air pollution caused by

automobiles and industries. Air pollution has

What is a "hazard" tree? A hazard tree contains

some form of structural defect, a peculiar location, or a

combination of both, giving it a high possibility of failing

and causing injury to people or property. To be considered a hazard tree requires a valuable target—buildings,

cars, or people—close to the tree. A rotten tree deep in

the forest away from people is not a hazard because no

target has been identified, but a rotten tree near a campsite, road, or home is a hazard.

many adverse effects on Northwest forests.

Ozone, a pollutant created from nitrogen oxides and volatile organic compounds (both byproducts of automobile emissions) and sunlight, damages a variety of plant species, with

symptoms ranging from leaf spotting to decreased growth to mortality.

Some plants, such as lichens,

are much more sensitive to

ozone than others and can be

used as ozone indicators. In

western Washington, the

number of lichen species, as

well as the concentration of

pollutants in lichen tissue, are

being monitored to identify

forested areas with ozone

damage.

Decayed trees are hazards in recreation sites—

Trees with root disease and

stem decays are potential hazards in recreation sites, particularly in stands where the

trees are old. Homes being

built among the trees in the

urban-forest interface are at

particular risk from decayed

trees, which can fail without

warning, damage homes, and

injure or kill people. Efforts

are being made to teach

homeowners, landscape planners, highway department employees, park staff members,
and other land managers to recognize and correct tree hazards. Corrective measures may

include tree removal, tree replacement, or

pruning. Planning so human activity areas are

away from hazard trees can reduce risk without altering the trees.

Douglas-Fir

Effects of laminated root rot differ with

site and use—Laminated root rot is widespread in southern British Columbia, Washington, Oregon, western Montana, and northern Idaho. It is believed to have co-evolved with

its hosts, making it a natural part of many forest ecosystems. It neither destroys huge expanses of forest nor threatens the existence of

host species, but it does cause subtle, persistent growth loss and mortality. The effect on

its primary host, Douglas-fir, varies with the

use or setting of the trees. When disease pockets are small and scattered, they increase the

structural diversity and benefit wildlife and understory plants. Large root-disease pockets in

areas designated for timber management cause

significant economic loss. In settings such as

parks, around homes, or along well-traveled

roads, the disease can threaten life and property.

Douglas-fir beetle increases after disturbances—Douglas -fir beetle is the most imporDouglas-fir beetle attacks large groups of

Douglas-fir only when large amounts of food

(downed trees) becomes available after

windstorms, fires, or logging.

Douglas-fir beetle activity decreased in 1995 in

Western Washington. Source: Cooperative Aerial Survey,

Washington Department of Natural Resources and USDA Forest Service.

tant bark beetle of Douglas-fir. In western

Washington, it attacks Douglas-fir 60 years old

or older; low populations are always present.

When populations are low, the beetle is relatively nonaggressive, attacking recently killed

(windthrown, snow-broken) or dying (root-rot

infected, defoliated, drought-stricken, firedamaged, wounded) trees. When many fresh

logs become available in a short period, from

such events as wind throw, fires, or logging, the

beetles can reproduce in them and quickly

reach outbreak populations. They can then

attack and kill healthy trees. Relatively pure

stands of Douglas-fir, 120 years old or older,

of low vigor from competition, drought, or diseases, are most at risk from beetle attack.

The 1995 cooperative aerial insect detection

survey reported more than 2,000 trees killed

by Douglas-fir beetle on about 3,000 acres in

western Washington, a three-fold decrease

from 1994. Because aerial surveyors detect

tree condition based on changes in foliage

color, trees that quickly lose their needles may

not be recorded.

Fog and off-site trees create an ideal

environment for needle disease—Swiss

needle cast is a native disease of Douglas-fir
"Bubble cops" containing MCH

protect high-value trees from

Douglas-fir beetle attack.

How to minimize Douglas-fir beetle damage.

Losses from Douglas-fir beetle may be reduced by

promptly removing fresh logs from the forest Extensive winter windthrow must be removed before beetles

emerge. Any standing, live trees that were killed

during the initial attack on logs should be removed as

well. Trees that have been dead a year or more are

generally no longer suitable habitat and need not be

removed. Salvage operations need to be carefully

planned and executed in a timely manner. Tree tops

and large limbs need to be piled or scattered away

from standing green trees to prevent emerging beetles

from attacking healthy trees. The experimental pheromone MCH, a Douglas-fir beetle anti-aggregant, could

be used in the future in selected areas such as campgrounds to protect trees from attack.

throughout the Coast Range and western Cascades. In most areas, the disease is of little

consequence, causing premature shedding of

3- and 4-year-old needles. Since the early

1980s, however, thousands of acres of Douglas-fir plantations in western Washington have

shown increasingly severe damage from this

disease. In late winter and early spring, diseased plantations appear noticeably yellow to

brownish yellow, in contrast to the adjacent,

green and vigorous natural stands. Individual

tree symptoms include severe chlorosis (yellowing), poor retention of needles, and reduced

height and diameter growth. With little foliage remaining for photosynthesis, tree growth

declines, and some trees eventually die. The

severity of symptoms differs considerably

among individuals in the Douglas-fir population, indicating that tolerance to infection exists in the species.

Trees with Swiss needle cast often retain only one or two year's worth of needles compared to the four

year's retained by healthy Douglas-fir (left). Diseased needles turn yellow and are easily shed (right).
Most plantations with severe symptoms are

10 to 25 years old and within 15 miles of the

coast in an area prone to fog; before they were

logged, these areas were dominated by hemlock, spruce, and cedar. Swiss needle cast also

infects plantations farther inland on the west

side, typically where large plantings of Douglas-fir occupy valleys surrounded by hills or

mountains, where poor air drainage contributes to the buildup of the fungus. These inland plantations usually recover from heavy

infection after 2 to 5 years, so changing them

to species other than Douglas-fir is unnecessary. The disease can be controlled with fungicides, but treatment in forest plantations is

uncommon and not usually advised.

Hemlock

Two dwarf mistletoes infect hemlock

trees—Western hemlock dwarf mistletoe is

the most widespread dwarf mistletoe in western Washington. Taxonomically, this parasitic plant is separated into two subspecies

that look almost identical but are specific to

the two species of hemlock found in western Washington: western hemlock and

mountain hemlock. Each subspecies also

infects a variety of true firs, spruces, and

pines to a much lesser extent than hemlock.

Western hemlock dwarf mistletoe is a serious parasite along the Pacific coast from

California north to Glacier Bay, Alaska. As

with all dwarf mistletoes, infected trees show

increased mortality, reduced growth, lower

fiber quality, and an increased susceptibility to other disturbance agents. Heavily infected trees show growth reduction in both

volume (40%) and height (84%) compared to

uninfected or lightly infected trees.

Mountain hemlock dwarf mistletoe is common on mountain hemlock and true firs in

northern California and the Oregon Cascades but, until recently, was thought to be

restricted to small populations in two areas

in Washington—north of Mount Baker and

in the southern Olympic Mountains. Surveys

conducted in 1995 in the Washington Cascades discovered at least three new, widely

separated populations of this parasite.

Hemlock infected by dwarf mistletoe is deformed,

grows less, and is often killed. The large tree on

the left is heavily infected with many mistletoe

"brooms" (excessive branch growth caused by

the infection).

Western hemlock looper is a pest of old

growth—The primary host for hemlock looper

is western hemlock, although it will feed on

other conifer species and understory shrubs

found in association with western hemlock.

Heavy, repeated defoliation during an outbreak

can result in tree mortality.

Western hemlock looper is generally very

successful in extensive, old-growth, western

hemlock forests. Early records of western

hemlock looper outbreaks show vast

amounts of timber killed in northwest Oregon and southwest Washington. Outbreaks

generally last about 3 years and are usually

brought under control by the natural action

of parasites, predators, and disease. Out-
Outbreaks of hemlock looper, an old-growth insect,

may increase on federal lands as harvesting decreases and more stands reach and exceed 100

years of age.

An outbreak of hemlock looper was detected in

1993 and 1994 in western Washington. The

population Collapsed in I 995. Source: Cooperative Aerial

Survey, Washington Department of Natural Resources and USDA Forest

Service.

breaks can also occur in vigorous 80- to 100-

year-old stands.

Today, the majority of stands that will support large hemlock looper populations are in

parks and reserves, mostly on federal lands in

northwest Washington. Those lands with 80-

to 100-year-old, vigorous western hemlock

stands or multistory older, predominantly mature timber are susceptible to hemlock looper

outbreaks.

The most recent defoliation from western

hemlock looper was found on the Mount

Baker-Snoqualmie National Forest. It was first

noticed during the 1992 aerial survey. The

outbreak peaked in 1993 with more than

49,000 acres defoliated. Populations collapsed

sometime between 1994 and 1995. In 1995,

extensive ground evaluations by forest health

specialists did not detect any live insects.

True Fir

True fir stands continue to be changed

by an introduced insect—The balsam woolly

adelgid, an insect native to Europe, was first

noticed in the Pacific Northwest in the 1930s

on true firs in the Willamette Valley in Oregon.

It gradually spread to true firs in the mountains. It slowly kills trees by infesting the twigs

and branches, or kills them quickly by infesting the bole. It causes gouting (swelling) of

branches and sometimes of the trunk. Damage and mortality are mostly confined to true

fir stands on federal lands, but it could spread

to all susceptible true fir stands. The Gifford

Pinchot, Mount Baker-Snoqualmie, and Olympic National Forests report the highest mortality associated with balsam woolly adelgid.

The number of acres with balsam woolly adelgid

damage in western Washington since 1969. Source:

Cooperative Aerial Survey, Washington Department of Natural Resources

and USDA Forest Service.
Wildlife habitat is affected by the decline of

whitebark pine. White pine blister rust, fire

exclusion, and mountain pine beetle continue to

cause decline in whitebark pine. This tree is a

prominent upper-subalpine species that is important

as a source of food and habitat for many animals,

including the grizzly bear, and is a keystone species

in high-altitude ecosystems. Studies in 1991 and

1992 in northwestern Montana showed the number

of mature whitebark pines rapidly decreasing.

Some whitebark pine stands in Glacier National

Park have mortality rates of up to 90%. Recently,

interest in the effects of blister rust on the survival of

whitebark pine in the northwestern portion of its

range, which includes Washington, has increased.

A preliminary survey in Mount Rainier National Park

completed in 1994 showed blister rust present in all

whitebark stands inventoried. Twenty-seven

percent of the plots within these stands had no

infected trees, supporting existing evidence that

whitebark pine exhibits a slight natural resistance

to the rust. Because the seeds of the tree are

spread by a bird, Clark's nutcracker, that caches

them in the ground, the most effective management

action to preserve this species would be to use fire

to make clearings in the thick, true fir stands so the

birds have a cleared place to hide the few seeds

produced by naturally resistant trees.

Balsam woolly adelgid has caused dieback and

death of hundreds of true fir since its introduction from Europe in the 1930s.

Photo courtesy of Russel Mitchell.

Hardwoods

A decade of summer drought damages

hardwoods—Nearly 10 years of continual

summer drought between 1987 and 1995 has

been hard on hardwoods in western Washington. The most commonly affected species are

red alder and bigleaf maple, although conifers

are affected as well. Damage has been widespread, found in the Puget Sound area, the

Cascade foothills, and the San Juan and Puget

Sound Islands. Moisture stress and resulting

damage or death occurs between June and

September. Symptoms range from scattered,

fading or red branches to whole tree mortality. Often whole stands are affected, some losing up to 50% of the trees. This type of damage is common on soils that dry rapidly in the
Annual precipitation in the western Cascades was

lower than average most of the years between 1985

and 1993. Source: Washington Department of Natural Resources.

summer, such as shallow, hardpan or deep,

gravelly soils.

Diseases or outbreaks of insects, such as

forest tent caterpillar on red alder in 1987, often are associated

with drought-stressed trees and

accelerate tree death. By themselves, many of these insects or

diseases rarely cause mortality.

Pacific dogwood is affected

by fungus—Since the early

1970s, the native dogwood in

western Washington has been infected by anthracnose, an introduced fungus disease of foliage

and stems, that is often fatal after a few years of infection. Many

west-side dogwoods have succumbed to the disease over the

last 20 years. Some stands that

had five dogwoods per acre 20

years ago may have none today.

In other areas, the disease is not

as common. Dogwood under -

story in the eastern parts of the

Columbia Gorge is generally

healthy.

Pacific madrone is injured by winter

freezes—Winter freezes periodically damage

tens of thousands of Pacific madrones throughout the Puget Sound region. Injury ranges

from leaf browning to branch dieback and tree

mortality. Trees with only leaf browning usually recover. Madrone trees with winter freeze

damage have been noted in 1972, 1985, and

1990. In the spring of 1996, madrones suffered nearly complete browning of the leaves.

Sometimes the leaves at the tops of the trees

were relatively undamaged. Often, affected

trees were found adjacent to completely uninjured trees. A weak parasitic fungus is suspected of colonizing the leaves after they were

stressed by cold weather in January 1996. Two

leaf-mining insects were also found in the injured leaves and probably contributed to about

one-third of the foliage damage. Emergence

of normal-appearing 1996 leaves nearly hid the

dead leaves. Whether the fungus can persist

and spread to the new leaves is unknown.

Leaf miners are one of several insects that attack Pacific

madrone.
EASTERN CASCADES (M242C) AND

OKANOGAN HIGHLANDS (M333A)

Ecology

Eastern Cascades—The eastern Cascades

region in Washington consists of the eastern

slopes of the Cascade Range, which extends

north into Canada and south into Oregon.

Elevation ranges from near sea level at the

Columbia River to more than 10,000 feet in the

high mountain peaks. Precipitation patterns

are the key force for determining vegetation in

Annosus root disease fungus produces spores that infect stumps;

the disease spreads from infected stumps to live trees by rootto-root contact.

the eastern Cascades. At high elevations that

receive more rain and snow, true fir, mountain hemlock, and Douglas-fir forests predominate. At lower elevations, where moisture is

sparse, ponderosa and lodgepole pines grow.

Lodgepole pine is common on dry sites with

poor soils. Local areas of whitebark pine, white

pine, Engelmann spruce, and aspen are also

found in the eastern Cascades. Fire periodicity is extremely variable. In the pine forests at

lower elevations, fire occurred at 10- to 15-year

intervals before fire suppression. Fire was less

frequent at higher elevations.

Okanogan Highlands—The Okanogan

highlands are characterized by moderate

slopes and broad, rounded summits. Several

north-south rivers flow in this region, including the Columbia, Okanogan, Colville, and

Pend Oreille Rivers. Vegetation patterns in the

Okanogan highlands are strongly influenced

by the east-west precipitation gradient. Precipitation averages 30 to 60 inches per year,

mostly as snow. Although ponderosa pine can

be found growing in pure stands, it is more

often found growing with other species in

mixed stands, including Douglas-fir, grand fir,

western larch, and lodgepole pine as major associates. At higher elevations,

Douglas-fir and true fir forests

predominate. Historical fire regimes ranged from frequent, lowintensity fires to infrequent,

high-intensity fires.

Mixed Conifers

Root diseases continue to

increase in eastern Washington—Laminated root rot is widespread throughout eastern

Washington forests. The disease

is increasingly common in the

mixed conifer stands of northeastern Washington, where

Douglas-fir and grand fir are

much more abundant in stands

once dominated by ponderosa

pine and western larch. Pine and

larch tend to be more tolerant of

the disease.
Annosus root disease has also increased in

distribution and severity as a result of management practices. Selective logging creates

abundant stumps of ponderosa pine, grand fir,

and Subalpine fir that can be infected by airborne spores. This increase in infection sites

is compounded by high tree densities that increase the probability of tree-to-tree spread

through root contact. Annosus root disease

is particularly common in mixed stands of true

fir and Douglas-fir of the southern Cascades

near Yakima and Goldendale.

Eastern Washington has areas with large

amounts of schweinitzii root and butt rot in

late seral and climax stands. The primary host

is Douglas-fir, but western larch, spruce, and

true fir are also infected. Infected trees rarely

The fungus that causes armillaria root

disease often produces edible mushrooms

at the base of infected trees.

Armillaria root disease. Incidence of

armillaria root disease is also on the rise

in the expanding Douglas-fir/grand fir

timber type; mortality has increased

because of stress from overstocking. The

disease is severe on Douglas-fir and

grand fir in northeastern Washington.

Armillaria is sometimes extremely aggressive and attacks trees that do not

appear to be under stress, such as

Ponderosa pine in pure pine stands

southeast of Mount Adams.

show outward signs of infection. The best way

to detect the root rot is to find the large, rusty

brown and often velvety, mushroom-like fruiting bodies on the ground near infected trees.

Infected wood is stained red in Douglas-fir, and

the advanced decay breaks down in reddishbrown cubes. As in other root diseases, infection usually starts in root tips rather than

through old fire scars or wounds, as was once

thought. Trees with extensive butt decay may

attract bark beetles and even armillaria root

disease.

Western spruce budworm damage is declining—Western spruce budworm is a common defoliator of Douglas-fir and true fir in the

Pacific Northwest, and outbreaks are frequent

in mixed-conifer stands. Repeatedly defoliated

trees show substantial radial-growth reduction, and are often predisposed to attack by

bark beetles. Effective fire prevention and suppression during this century have eliminated

many major fires and nearly all surface fires.

As a result, forests that have had no other disturbances, such as timber harvesting, have

moved steadily toward climax and, consequently, an abundant and expanding source

of the insect's favorite food—shade-tolerant,

late-successional tree species.

Western spruce budworm larvae prefer new

foliage, but also feed on older foliage when new

foliage is in short supply.

CONTINUED
The number of acres defoliated by western spruce budworm has declined sharply since 1992 (left)

compared to 1995 (right), especially in the Okanogan area (northeast corner of the state). Source:

Cooperative Aerial Survey, Washington Department of Natural Resources and USDA Forest Service.

Budworm populations have declined significantly since 1992, when over 1.3 million acres

showed some defoliation in eastern Washington. The decline is attributed to a natural collapse of the insect population and increased

precipitation. Areas of budworm defoliation

increased slightly in 1995 compared with 1994.

Dwarf mistletoe abundance is tied to

host distribution, fire, and harvest—Dwarf

mistletoes are found on all of the conifers in

the mixed conifer forests of eastern Washington. The distribution and frequency of dwarf

mistletoe species closely follows the distribution and frequency of their hosts. Before 1900,

western larch dwarf mistletoe was the most

widespread mistletoe in late seral stands.

Western larch is less prevalent today but, because of selective harvest which creates conditions favorable to spreading mistletoe, the

remaining larch have a high incidence of dwarf

mistletoe.

In stands east of the Cascades, ponderosa

and lodgepole pine dwarf mistletoes were historically more localized and less damaging than

now because of the frequency and sanitizing

effects of natural ground fires. Frequent

underburning minimized the accumulation of

fuels and the likelihood of stand-replacing fires.

Many stands had some dwarf mistletoe infection, but the severity was continually reduced

by the frequent fires. In lodgepole pine, standreplacing fires at intervals of 90 to 200 years

eliminated mistletoe, along with the trees. In

Ponderosa pine stands, fire suppression has

led to more widespread dwarf mistletoe.

In ponderosa pine stands that have converted to true fir and Douglas-fir because of

fire suppression, pine dwarf mistletoes have

decreased and fir mistletoes have increased.

Western larch dwarf mistletoe can be extremely

damaging; mistletoe brooms on larch are brittle

and break off, leaving infected trees with few

branches.
At least 43% of the Douglas-fir stands east of

the Cascades are estimated to be infected with

dwarf mistletoe. Infections are more widely

distributed and more severely damaging than

ever before.

Ecologically important features of the dwarf

mistletoe are the wildlife food and habitat their

flowers, seeds, and witches brooms provide.

Brooms, which are caused by the reaction of

the host tree to hormones produced by the

parasite, are large masses of branches, twigs,

and needles. Brooms are often retained on the

tree after healthy branches are shed and provide dense platforms, either close to the tree

trunk or scattered about the crown. Brooms

are used for nesting, roosting, and hiding cover

by small mammals and birds, especially owls,

hawks, and grouse.

Drought, defoliation, and disease contribute to susceptibility to bark beetles—

In eastern Washington, the Douglas-fir beetle

normally breeds in felled, injured, or diseased

trees. Drought, root diseases, and repeated

years of defoliation by western spruce budworm increase the susceptibility of Douglasfir to this beetle by reducing the tree's ability

to resist attack. Mortality is widely scattered

when beetle populations are low, but outbreak

populations can kill apparently healthy trees

over extensive areas.

The fir engraver infests true firs in eastern

Washington. It attacks pole-sized and mature

trees, causing significant mortality during outbreaks. Outbreaks often occur during and after periods of drought. Trees with root disease

are especially susceptible to attack. Trees defoliated by western spruce budworm also are

likely to be attacked. The fir engraver commonly breeds in slash and windthrown trees.

Pines

Mountain pine beetle causes mortality of

many pines—Mountain pine beetle occurs

throughout the range of pine in the Pacific

Northwest. Infestations have resulted in extensive mortality over large areas. In 1995,

mountain pine beetle in eastern Washington

was reported to have killed 406,000 trees of

four different species of pine on 201,000 acres.

Precipitation in northeastern Washington was lower than normal most years between 1985 and

1994 (left). Fir engraver activity was also highest during this period (right). Source: Washington Department of

Natural Resources (precipitation data); Cooperative Aerial Survey, Washington Department of Natural Resources and USDA Forest Service (insect data).
Long-term management for

the Loomis State Forest The

Loomis State Forest, west of

Tonasket is the largest block of

state-owned forest land in

Washington. In addition to its

designation as a common school

trust land, managed to produce

income for construction of public

schools, the Loomis State Forest

provides valuable habitat for the

threatened North American lynx,

roadless recreation sites adjacent to the Pasayteri Wilderness

Area, water resources for

downstream communities, and

grazing land. Controversy has

surrounded potential management of the forest, especially

when such uses conflict.

In the late 1980s, a mountain

pine beetle outbreak began to

visibly affect portions of the

Loomis State Forest containing

old, large-diameter lodgepole

pine. By 1993, more than

20,000 acres had been affected,

with an average of 40% of the timber volume killed on those sites. About 28,000 acres

containing large-diameter lodgepole pine continue to be at risk of attack.

The Loomis State Forest is the largest contiguous block

(144,000 acres) of land managed by the Washington

State Department of Natural Resources.

To address numerous and conflicting concerns about managing this block, an 80-year

plan has been prepared and approved. The Department of Natural Resources plans to

accelerate harvest in the beetle-susceptible lodgepole pine stands and create a better

mosaic of age structure. This strategy will improve lynx habitat and increase stand

resistance to future attack by the beetles, while not precluding other forest uses.

Table 3-1—Effects of mountain pine beetle on eastern Washington pines

Effects

Greatest

impact

How it kills

Trees

killed in

1995 (no.)

Acres

affected in

1995 (no.)

Lodgepole

pine

High-density

mature trees

Many trees over

extensive area

342,000

122,000

Ponderosa

pine

Immature

pole-sized

Groups of

several 100

52,000

58,000

Western white

pine

Big, old(>250

yr) trees

Individuals

11,000

14,000

Whitebark

pine

Big, old

trees

Individuals

1,000

7,000
Western pine beetle kills

big, old, ponderosa pine—

Western pine beetle sometimes attacks ponderosa pine

in the Pacific Northwest. Normally, this beetle breeds in

large, old trees; in windfalls; in

trees infected by root disease;

or in trees weakened by

drought, overstocking, or fires.

Losses are significant because

large, old pines are under-represented across the forested

landscape in many areas in

eastern Washington. Western

pine beetle also attacks and

kills trees of all ages that have

bark sufficiently thick to protect the insect during development.

Aspen

Satin moth and moisture

stress are killing many

aspen stands—Defoliation by

satin moth has killed many aspen stands in

north-central and northeastern Washington. the late 1920s

Affected stands tend to be older than unaf- logical control

Large, old, ponderosa pine, important for their ecological and

scenic value, are being killed by

bark beetles in overstocked

stands, especially in dry years.

fected ones and apparently

unable to withstand insect defoliation. Moisture stress was

likely a factor in the mortality.

The defoliated stands were isolated from other hardwood

stands and do not have many

predators or parasites to keep

the satin moth populations in

check.

Satin moth, introduced

from Europe, was first found

in North America in 1920,

both in New England and in

southwestern British Columbia. In the West, it has spread

southward to northern California, and into the interior of

Oregon, Washington, and

southern British Columbia.

After its introduction into British Columbia, the satin moth

was considered a pest of economic importance. With the

introduction of European

parasites of the moth during

and early 1930s, successful biohas generally been achieved.

Satin moth larvae feed on aspen

leaves (above). Entire groves of aspen

can be defoliated by the satin moth

(right). Older, moisture-stressed trees

are the most vulnerable.
CHAPTER 4. DISTURBANCE AND URBAN

FOREST HEALTH

Introduction

An urban or community forest is the sum

of planted landscape trees and remnants of the

native forest intentionally or inadvertently left

behind during the building of the city. Urban

forestry is the discipline concerned with managing these forests.

Urban forest health is less than ideal—

The health of Oregon's and Washington's community forests is poor in many towns and cities. Erratic maintenance, old age, lack of

species diversity, insects and diseases, development pressures, and weather combine to

create a myriad of problems for urban trees.

Although Oregon and Washington have been

at the forefront in traditional forest management, their urban forestry practices have

lagged significantly behind other regions of the

United States.

Most community forests have aging or

overmature trees. Many of these trees were

planted and left without adequate care, and

others simply were the wrong trees in the

wrong places. In Oregon and Washington cities, tree replacement consistently lags behind

tree removal, but recent surveys of Northwest

communities show that tree planting is increasing.

East of the Cascades, environmental

changes, tree age, and pests are taking a great

toll on community trees. Historically, the region was planted with a few hardwood species,

such as black locust, Siberian elm, poplars,

and various conifers. Although tenacious,

these species have characteristics some people

consider undesirable, such as weak wood,

messy fruit, and prolific sprouting, which can

result in high maintenance costs. Replacing

them with a diverse selection of more appropriate species or cultivars will reduce maintenance costs and improve the health of the urban forest.

Tree topping stresses urban trees. Many landscape trees have suffered from "topping," the practice

of indiscriminantly removing the large branches in the

crown of a tree. Because trees need leaves to produce energy, removing the canopy causes trees to

slowly starve. With this stress, trees become more

susceptible to insect and disease damage. Wounds

created by topping provide places of entry for decay

organisms. The resulting decay often goes unseen

and undetected until the tree fails. Dead wood and

poor branch structure also contribute total and costly

tree failures.
Community forests have not escaped the

insect and disease outbreaks plaguing the rural forests. Many conifers like Douglas-fir and

Ponderosa pine are found in both rural and

urban areas, and so too are the insects and

diseases that afflict them. Management of the

recent pandora moth outbreak in central Oregon, for example, not only concerns the

Deschutes National Forest, but also the city

of Bend—though on a different scale. Descriptions of the more important insects and diseases of urban forests follow.

Disturbance Agents In Urban Settings

Fire and windthrow are a potential

threat to homes in forested areas—Homes,

increasingly being built at the urban-forest

interface, are at risk of being destroyed or damaged by wildfires or falling trees. Trees with

internal decay or root disease (such as laminated root rot) are particularly susceptible to

windthrow or breakage during wind or ice

storms. Thinning or removal of groups of trees

to accommodate house construction may also

lead to windthrow during storms; the remaining trees are often unstable because of heightto-diameter ratio and altered wind patterns.

Home owners need to know that managing the

vegetation around their homes is essential to

protect their lives and prevent property damage. Where vegetation is not properly managed, the costs of fire protection and storm

clean-up increases for neighbors, the community, and public agencies.

Root rot disease often creates hazards when

houses are built in forests (top). Removal of

hazardous trees can be costly and unsightly

(bottom).

Removing or thinning trees during home

construction can cause remaining trees to be

unstable and prone to windthrow.
Dutch elm disease in western Oregon, 1986

to 1995. The 1986 figures are from Eugene

and Portland. The 1987 to 1995 figures are

removals from Portland, plus a few trees from

private home owners outside of Portland.

Source: Oregon Department of Agriculture.

Dutch elm disease is increasing in

Oregon and Washington—American elm is an

important component of the mature urban forest environment, both east and west of the

Cascades in the Pacific Northwest. Dutch elm

disease is an introduced disease that has devastated trees throughout the United States and

is of worldwide importance. This aggressive

disease is spread from tree to tree by elm bark

beetles, which carry disease spores, and also

when the fungus grows from roots of an infected tree to roots of adjacent healthy trees.

Dutch elm disease was first detected in Oregon in the Nyssa-Ontario area and in Washington in Walla Walla in the 1970s. Despite

control efforts, the disease has since spread

to other locations throughout the two states.

The key to reducing spread and losses from

this disease is prompt removal and disposal

of infected trees, but many cities and towns

have no such programs. In Oregon, many

towns remove infected trees and dispose of the

chipped wood at a solid waste site. The city of

Portland injects elm trees with fungicides as a

protectant against the disease.

Gypsy moth—the vigil continues—The

first European gypsy moths were discovered

in 1974 in Washington in the city of Renton

(near Seattle) and in 1979 in Oregon in Lake

Oswego (near Portland). Since then, gypsy

moth has been monitored annually by the Oregon and Washington Departments of Agriculture. In 1995, more than 50,000 traps were

deployed in Oregon and Washington, mostly

west of the Cascades, where most population

centers and gypsy moth host material are located.

The 1995 gypsy moth monitoring in Oregon

and Washington had the following results:

Traps placed (no.)

Total catch areas

Total moths (no.)

European

Asian

Hybrid

Oregon

14,585

10

24

24

0

0

Washington

36,166

40

149

146

3

0

The newest arrival is the Asian gypsy moth;

it is potentially more serious than the European gypsy moth because females can fly, and

they have an appetite for conifers. In the last

The European gypsy moth larva, pictured here,

feeds mainly on hardwood foliage. Its cousin, the

Asian gypsy moth, feeds on conifers and so

presents a greater threat to the Pacific

Northwest.
Gypsy moth was trapped in 13 counties in

Oregon and Washington in 1995.

Table 4-1—Gypsy moth eradication sites in 1996

The Oregon Department of Agriculture keeps a

steady watch on the gypsy moth through an

extensive trapping program.

State

Oregon

Washington

County

Multnomah

Clark

King

Pierce

Thurston

City

Gresham

Vancouver-Union

Seattle-Beacon Hill

Seattle-Beacon Hill

Seattle-Madrone Park

Tacoma-Hillsdale

Tacoma-Proctor

Bonney Lake-Highlands

Black Lake

Hunter Point

Acres

10

110

660

360

590

13

19

14

400

19

Treatment

Ground application of Bta

Ground application of Bt

Ground application of Bt

Aerial application of Bt

Aerial application of Bt

Ground application of Bt

Ground application of Bt

Ground application of Bt

Aerial application of Bt

Ground application of Bt

Bt is a microbial insecticide, composed of the bacterium, Bacillus thuringiensis.

few years, several Asian gypsy moths have been

trapped in Washington and British Columbia

and one in Oregon, near ports where they have

arrived on ships.

The largest outbreak in the United States

was in 1984, followed by the largest control ef- fort in 1985: 227,000 acres near Eugene, Oregon, were treated with aerial applications of

Bacillus thuringiensis (Bt), a microbial insecti- cide. In 1996, 10 sites in Oregon and Wash- ington were treated with Bt to eradicate the

moth. Treatment areas are selected on the

basis of gypsy moth species (Asian or Euro- pean], size of the population, and number of
egg masses. Past eradication treatments have

been successful and, fortunately, neither the

European nor the Asian gypsy moth has become established in the Pacific Northwest. The

gypsy moth, however, is constantly being reintroduced, so annual monitoring is necessary.

Dogwood anthracnose disease causes leaf blight,

branch dieback, and tree death of ornamental

and native dogwoods.

Dogwood anthracnose has become established in the Pacific Northwest—Dogwood

anthracnose, a very destructive disease of flowering dogwood, first appeared in the eastern

United States in the early 1970s. It was first

reported on native Pacific dogwood in Washington in 1976 and in Oregon in 1983. As of

1994, the disease was present on Pacific dogwood in most western Oregon and Washington counties. Evidence suggests that this disease was introduced from abroad, but its origin

remains unknown.

The disease causes leaf blight, branch dieback, and tree death on Pacific dogwood and

several ornamental cultivars, and it is of particular concern in ornamental landscapes. The

greatest hope for long-term disease management is to develop disease-resistant dogwoods.

Environmental stresses affect urban

trees—Environmental stresses, such as too

much or too little water, affect the health of

trees in communities. Urban forests generally

lack the complex forest floor that helps trees

retain moisture and nutrients. Drought over

prolonged periods can reduce the vigor of mature trees and increase their susceptibility to

insects and disease. Supplemental irrigation,

even for established trees, is beneficial during

dry, hot weather, but too much water can also

be detrimental. Excessive summer irrigation,

for example, leads to root rot and structural

instability in Oregon white oaks.

Building and maintaining cities affects tree

health. Many existing tree health problems can

be traced to soil compaction and root damage

during construction, utility trenching, or power

line clearance. Decay organisms enter mechanical wounds and can create hazard trees.

Pollution caused by automobile and industrial

emissions also affects the health and longevity of community forests.

Proper care and species selection will improve the health of urban trees—The careful observation and inventory of urban trees

will detect many disease and insect problems.

Given adequate funding, many can be treated.

A diversity of tree species lessens the risk of

catastrophic losses from weather extremes or

introduced pests. Choosing the right tree for

the right place, and regular pruning to remove

dead wood and excessive twig growth will help

keep trees healthy. As urban forests mature,

the loss of older trees is inevitable. If communities maintain mature trees and plant new

trees, their forests will be healthier and future

generations will enjoy a thriving urban forest.
Commitment is needed for long-term urban

forest health. Commitment of citizens and local

governments to long-term health of their community

trees will result in thriving urban forests. Interest in

maintaining and improving the trees in their neighborhoods and towns is incredibly strong among

residents and community organizations. Urban trees make towns and cities more livable,

clean the air, screen noise, please the eye, and provide habitat for birds and other small

animals; through these amenities, they make a city more attractive to potential businesses,

tourists, and other sources of income. Policy makers should recognize that community trees

are a worthwhile investment of time and money.
CHAPTER 5. FOREST HEALTH MONITORING

PILOT PROJECT IN OREGON AND WASHINGTON

Implementing the national Forest Health Monitoring Program. Step I: measure indicators of forest

condition from permanent field plots, aerial surveys, and other ground surveys; Step 2: analyze and

interpret the results for various user groups; Step 3: determine how existing and future information

can be used to answer specific (assessment) questions about forest ecosystems at national and

regional scales.

The Forest Health Monitoring Program is a

multiagency national effort to monitor, assess,

and report on the long-term status, changes,

and trends in forest ecosystem health in the

United States. (See appendix 4 for definitions

of the kinds of forest health monitoring activities.) Data from permanent field plots and

other sources are used to prepare annual summaries and periodic regional and national reports on forest health for the general public,

universities, resource managers, and Congress. Some important national and regional

assessment questions that can be answered

from uniformly collected field data are:

• What proportion of the Nation's forests has

reduced growth from past records?

• Where are the risks of reduced growth increasing or decreasing?

• Is the scenic quality of forests decreasing

because of more observed damage?
Forest Health Monitoring 1994 field plots in

California, Oregon, and Washington.

In summer 1994, Forest Health Monitoring

protocols were used to sample forest conditions

of Douglas-fir habitats in Oregon and Washington, from the Cascade Range crest westward

to the Pacific Ocean. This work tested the ease

of measuring various indicators of forest health

in environmental conditions wetter than those

in California. It also familiarized state forestry

cooperators with field protocols they would be

using in their forest health monitoring work

and established baseline conditions for Douglas-fir forests related to the different indicators measured. Establishing and interpreting

baseline conditions (see appendix 4) is critical

to reviewing management options for oldgrowth stands and adaptive management areas. Results from this work, hereafter called

the Pilot Study, are explained in the rest of this

chapter. Many forest health monitoring indicators (table 5-1) have been tested for 6 years

in regional pilot studies across the United

States. The following sections define those

indicators measured in the Pilot Study, describe results from field sampling, and interpret their significance for Northwest forests.

When possible, Pilot Study results are compared to 4-year Forest Health Monitoring data

from about 200 plots measured in California,

1992 to 1995.

GENERAL SITE AND SPECIES

CHARACTERISTICS

Twenty-five plots, each about 2.47 acres,

were sampled in the Pilot Study—12 in Washington and 13 in Oregon. Elevations ranged

from <30 feet to about 7,600 feet. Stand ages

ranged from <10 to 300 years. Oregon sites

were older, at higher elevations, and on steeper

slopes than Washington sites; aspects varied

across both states. Conifers were the dominant vegetation. As expected, the predominant

forest type on the 25 plots was Douglas-fir

Table 5-1—Forest Health Monitoring indicators to

assess forest ecosystem condition

Indicators Indicators cont.

Growth Regeneration

Crown condition Mortality

Leaf area Tree damage

Plant species composition Soils:

Lichen community structure Acidification index

Bioindicator plants Organic carbon status

Songbird habitat Disturbance recovery

Nitrogen index index
(70%), followed by hemlock-spruce (17%); some

plots had small amounts (about 4% each) of

fir-spruce, mixed conifer, or other softwoods.

Stand Characteristics

Each forest stand has unique understory

and overstory traits distinguishing it from other

stands with similar or different species. Together, these traits are called stand characterForest Health Monitoring field plot layout.

istics. Tree and seedling characteristics at

Pilot Study sites were measured in four circular microplots and subplots of known size,

permitting results to be calculated per unit

area. Economic, scenic, and biodiversity values can then be attributed to larger landscapesized areas, allowing resource managers to

decide between different management options.

Understory Vegetation

Presence and abundance of understory

cover indicate status of seedling regeneration,

percentages of various vegetation ground cover,

and which ground cover may be competing

with new or established seedlings for soil moisture and nutrients. Understory measurements

were taken in small microplots, at right angles

to each subplot. Ground-cover percentages for

Pilot Study sites are shown in the figure above.

Pilot Study plots had about the same percentage cover for herbs, lichens, and seedlings

as did the 1992-95 California plots. Shrub

cover was twice, fern cover was nine times, and

moss cover was ten times higher in Pilot Study

plots. Pilot Study seedlings seem to face

greater competition from shrubs and ferns

than do plot seedlings in California, probably

because of wetter growing conditions.

Overstory Vegetation

Forest managers commonly summarize

characteristics of small and large trees—saplings, poles, and sawtimber—growing above the

forest floor and having similar height and diameter limits (table 5-2). Seedlings and saplings were recorded within microplots and pole

and sawtimber-sized trees within subplots.

Field tallies showed 79 sapling, 448 pole, and

275 sawtimber trees.

Table 5-2—Size classes of forest ecosystem

components

Class Range limit

Understory seedling < 1 ft tall

Seedlings > 1 ft tall & < 1.0 inch diameter

Saplings > 1.0 to 4.99 inch diameter

Poles 5.0 to 10.99 inch diameter

Sawtimber

(hardwood and softwood) at least 1 1.0 inch diameter
The average number of subplot saplings

found in 1992-95 California plots, four individuals, was almost the same as the average

for the Pilot Study plots, three individuals.

Pilot Study sites, however, had one-third more

pole (18 vs. 12 individuals) and about twice as

many sawtimber trees (11 vs. 6 individuals).

More plot and unit-area pole and sawtimber

trees in Oregon and Washington (table 5-3)

probably reflect older stands that have more

overstory trees. Washington plots had characteristics of younger stands compared to Oregon plots: twice the number of saplings and

about 1.5 times as many poles.

in managed and unmanaged stands (table 5-

4). Higher values in Oregon reflect those for

older stands. In the California 1992-95 data,

live basal area averaged about 96 square feet/

acre, including pole and sawtimber trees for

all species.

Basal Area

Basal area is a measure of the total crosssectional area of tree boles at breast height

in square feet. The higher the value,

the more cross-sectional area is occupied by bole wood. How the bole

wood is partitioned, however, determines economic value as well as influences habitat diversity. If large

total basal area is spread over

many very small stems, they are

probably not merchantable for

posts, poles, or pulp. Many

small old stems produce

densely shaded stands that do

not usually allow growth of

thick understory vegetation.

The average live basal area

combined for poles and sawtimber was 204 square

feet/acre in Oregon, and

154 square feet/acre in

Washington. These values are well within

ranges typically found

CROWN RATINGS

Many factors affect seedling and tree growth:

internal factors are vigor and age of the plant

and external ones are light, water, and nutrients. Light reaching a tree or seedling is influenced by the individual's position in the

canopy; relative position to neighbors; and the

shape, size, and condition of the crown. Thus,

crown evaluations indicate whole tree condiTotal height 4.5 ft (1.4 meters) 4.5 ft (1.4 meters) 4.3 ft (1.3 meters)

Crown length 1.9 ft (0.6 meters) 1.4 ft (0.4 meters) 0.6 ft (0.2 meters)

Live crown ratio 42% 31% 14%

Sapling crown vigor classes.

Table 5-4—Basal areas typically found for different

species and age classes in Northwest forests

Species Basal area ranges

(age range in yr) (ft2/acre)

Douglas-fir (0-750) 20-180+

Western hemlock (100-500+) 40-180

Western redcedar (100-500+) 0-80+

Red alder (0-100) 0-20

Table 5-3—Plot structure data for the Northwest Bigleaf maple (100-400) 0-20

Pilot Study

Data Oregon Washington

Number of trees per acre

Saplings 78 159

Poles 45 63

Sawtimber 33 34

Totals 156 256
tion by indirectly assessing its

ability to capture light and

produce carbohydrates by

photosynthesis. Crown condition indicators used in this report are sapling crown vigor,

crown density, crown dieback,

and foliage transparency.

Sapling Crown Vigor

Sapling crown vigor was

evaluated for 79 saplings.

High ratings in the good and

average categories (vigor class

1 and vigor class 2) indicate more foliage area available for photosynthesis.

Across all species, the sum of good and

average sapling vigor was 94%; only five

saplings (6%) had poor vigor (vigor class

3). Almost twice as many hardwood saplings had good vigor compared to softwood saplings, but the sum of good and

average vigor for both was >90%. Over

90% of all saplings in the Pilot Study and

California 1992-95 plots had high (good

+ average) crown vigor ratings.

Crown Density

Crown density represents the relative

amount of foliage, branches, and reproductive structures that obstruct skylight

visibility through the crown. Young and

old trees with vigorous growth generally

have full crowns and high density values—a condition indicating more foliage

area available for photosynthesis. Including all species and trees, 96% of Pilot Study trees had high (good + average)

crown density ratings. Hardwoods had

a lower percentage of good ratings but a

larger percentage of average ratings.

These findings were similar for all trees

and species by state. The lower percentage of good ratings in Oregon probably

reflects lower vigor of older stands

sampled there.

Crown density, crown dieback, and foliage

transparency rating example.
Crown Dieback

Crown dieback is the total percentage of

branch tips dying back from the crown

perimeter, except dieback caused by shading

and competition from neighboring trees. Dieback is caused by severe shock to root systems

from drought

or disease.

Some species

also will show

light dieback

as part of

their normal

growth, but

too much dieback reduces

foliage area

available for

photosynthesis. No crown

dieback was detected on 95% of Northwest Pilot Study trees. The no-damage class was split

about equally between hardwoods and softwoods. By state, percentages

of trees with none, light, moderate, and severe ratings were

almost identical to those ratings when all Pilot Study trees

were combined.

In the Pilot Study, western

hemlock comprised 1% of the

total population's severe dieback and the "Other Hardwoods" class had 6% severe

dieback. In the 1992-95 California data, oaks comprised

about 1% and fir-spruce about 1.5% of plot

trees with severe dieback. Severe dieback was

noted for all major species groups in the 4

years of California data, but some species were

affected more in certain years. For example,

Douglas-fir, oak, redwood-sequoia, and true fir

all had severe dieback in 1992—the end of a

7-year drought. Only oaks in 1993 and 1994

and only oaks and pine in 1995 had severe dieback.

Foliage Transparency

Foliage transparency measures light filtering through needles and leaves in the crown.

Transparency values differ by species and depend on natural branching habit and foliage

orientation. High transparency values indicate

unhealthy crown conditions because less foliage area is available for photosynthesis. Reduced foliage area can be caused by insects,

disease, and other stressors. In Pilot Study

plots, 98% of all trees had normal (0-30%)

transparency ratings. A slightly higher per-
centage of softwoods than hardwoods had normal transparency ratings; this trend was reversed for moderate (31-50%) and severe

(>50%) transparency classes. By state, about

98% of all trees had normal transparency ratings. Trees in both Pilot Study and the 1992-

95 California plots had almost identical high

percentages (>95%) of trees with good and

moderate transparency ratings.

DAMAGE

Pathogens, insects, air pollution, and other

natural or human disturbances can affect tree

growth and development. Damage caused by

any agent, alone or in combination, can influence forest condition. Recording observable

damage signs and symptoms provides valuable

information to assess forest condition and to

interpret any deviations from baseline conditions. Field crews recorded damage symptoms

seen in field plots when the observed damage

could kill the tree or affect its long-term survival.

Damage codes have two parts: the general

location of injury and the damage type (table

5-5). Data are recorded for all live microplot

saplings and all subplot live trees. Trees are

observed from all sides, starting at the roots.

Priorities are set for damage signs and symptoms and recorded by general location in the

following order: roots, roots and lower bole,

lower bole, lower and upper bole, upper bole,

crown stem, branches, buds and shoots, and

foliage. The numeric order (table 5-5) denotes

decreasing significance as the code number

goes up—for example, damage code 02
(conks—internal fungal decay) is more significant than code 03 (open wounds). This ranking is developed by insect and disease specialists who have found that the most serious

kinds of damage are those nearest the ground

where a tree's main stem is anchored in the

soil. When more than a single type of damage

is in the same place, the most damaging symptom (lowest damage code) is recorded. Damage is recorded for up to three locations on one

tree. Specific causal agents are not identified

in detection-monitoring field assessments but

a determining cause is critical in evaluation

monitoring (appendix D).

About 80% of the Pilot

Study trees and 75% of California trees had no damage

symptoms. The no-damage

percentage for California reserve (national parks, wilderness) and drier woodland areas, however, was about 60%.

The most common damage

symptoms were conks, dead

terminal branches, and open

wounds, which together represented about 10% of all trees.

Conk damage, indicating interior fungal decay in the tree

bole and stem, was the greatest single damaging agent

both in the Pilot Study and the 1992-95 California plots. The no-damage percentage of

about 80% for all trees across all three states

was not anticipated because tree species, climate, environments, disease, and insect factors differ so widely from north to south along

the Pacific Coast. The lower 60% no-damage

value for reserve and woodland land classes

in California means that older stands or more

stressed environments have a lower no-damage baseline. A major deviation from these nodamage baseline values of 60 and 80% will

indicate presence of one or more significant

stressors.

FULL-HECTARE TALLY

The full-hectare (2.47 acre) tally is done only

in the Pacific Northwest and in California, at

the request of federal and state cooperators

who provide additional funding for its implementation. Need for the extra tally arose in

summer 1991 when a California pilot plot in a

sequoia forest had no recently dead or live large

trees in any of the four subplots. Because the

overstory of many Northwest forest types has

similarly large trees, the concern of California,

Oregon, and Washington state cooperators was

that subplots would not capture a representative number of large live and dead trees.

Thus, protocols were changed so that field

crews searched the entire 2.47-acre plot area

for both large recent dead trees (>11.0 inches)

Table 5-5—Damage types recorded in the 1996 Pilot Study

Damage Description Severity threshold percentage

code (in 10% classes to 99%)

01 Canker 20

02 Conks, fruiting bodies, and other indicators None

03 Open wounds 20

04 Resinosis or gummosis 20

11 Broken bole or roots <3 ft from bole None

12 Brooms on roots or bole None

13 Broken or dead roots, >3 ft from bole 20

21 Loss of apical dominance; dead terminal 1

22 Broken or dead branches 20

23 Excessive branching or brooms 20

24 Damaged foliage or shoots 30

25 Discoloration of foliage 30

31 Other None

CONTINUED
that had died in the last 5 years and large live

trees (>40 inches).

Pilot Study subplots had almost no recent

mortality (1 vs. 55) and few large live trees (5

vs. 93) compared to numbers tallied on fullhectare plots. More large live trees were found

on 25 plots in Oregon and Washington in 1994

than were recorded for almost 200 California

plots measured in 1992-95. Pilot Study field

work was restricted to Douglas-fir habitats in

western Oregon and Washington. These forests have a high percentage of large-diameter

trees not tallied in subplot-only data. The significance of this work is that larger plots will

be needed to characterize true overstory conditions in Oregon and Washington forests when

operational field work starts in the future.

Published results for 1992-95 California forest health monitoring data show that per area

estimates of recently dead trees based on subplot-only data were significantly different than

estimates made from the full-hectare tallies.

VEGETATION STRUCTURE

Vegetation structure indicators provide information on species composition, relative

cover amount, and spatial distribution of vascular plants in the forest. Vegetation measurements help describe plant biodiversity and

quantify habitat structure, which in turn influences wildlife biodiversity and distribution

in forest ecosystems. Vegetation structure

indicators provide a natural link to other indicators including songbird habitat, crown

condition, regeneration, and species diversity.

Vegetation observations and collections are

taken in 10.8-square-foot permanent quadrats;

each subplot has three quadrats. Three kinds

of information are taken for each quadrat: species identification, height class in which each

species occurs, and plant canopy cover. Data

were collected for four strata: stratum 1 is from

the ground to 2 feet; stratum 2 is from 2 to 6

feet; stratum 3 is from 6 to 16 feet; and stratum 4 is from 16 feet to the forest canopy.

Botanists worked from the lowest stratum

upward and used a calibrated range pole and

the quadrat frame to define the sample area.

Specimens of unknown plants were collected

outside the subplots, dried, pressed, labeled,

and submitted to the Oregon State University

Herbarium, Corvallis, for identification.

Some 193 species were identified in 25

Pilot Study plots. Eleven species were found

at 9 or more of the 25 sample sites (table 5-6).

As expected, ground and understory layers

(strata 1 and 2) had the most species and highest number of observations per species. Stratum 4 had the greatest total cover and the

fewest species.

Botanists collect vegetation structure information

in subplot quadrats.
LICHEN COMMUNITIES1

Lichen communities provide information

about several key monitoring questions such

as contamination of natural resources,

biodiversity, and sustainability of resource

production. Hundreds of papers published

worldwide in the last century document the

close relation of lichen communities to air pollution, especially nitrogen and sulfur-based

pollutants. Sensitivity of epiphytic lichens

apparently results from their lack of a cuticle

'Adapted from: Cooperative Agreement Report: Lichen communities-Pacific Northwest Pilot Study, 1994. Peter Neitlich, Bruce McCune, and Jeri Peck, Botany Department, Oregon State University, Corvallis, OR. 1996. 9 p.

Macrolichens on woody substrate.

and their total reliance on atmospheric sources

of nutrition. Lichens thus provide a direct indication of air pollution effects and can be indirectly related to forest productivity.

Because lichens are linked to several human-induced environmental stressors, they

may be a key indicator of general forest condition. To test this idea, lichens have been

sampled in forest health monitoring plots in

several regions of the United States since 1990.

Sampled flora is restricted to macrolichens on

living or standing dead woody substrates.

Small microlichens are excluded because they

are difficult to sample. These collection restrictions standardize measurements to a class of

substrates that can be found at all sites. For

example, lichens are usually abundant and

diverse on rocks but many field sites have no

surface rocks.

Field workers collected macrolichens on

woody plants, excluding the 1.6-foot basal

portions of trees and shrubs. They estimated

abundance of each species using a four-step

scale. Accurately assigning species names to

collected lichens was not necessary because

all specimens were sent to a specialist for identification.

Table 5-6—Most common plant species

Common name Sites (no.)

Acrobolbus 9

Red alder 9

Twin flower 10

Oregongrape 10

Red blueberry 10

Western salal 13

Starflower 13

Pacific blackberry 16

Western hemlock 16

Sword fern 17

Douglas-fir 20
The total number of species found in Oregon

and Washington combined was 82. Species

richness (the number of species per plot)

ranged from 7 to 30 and averaged 15. At least

8 species were found on >50% of 25 field plots2.

General conclusions from the lichen collection

work were:

• The lichen community sampling method was

used effectively in the Pacific Northwest without altering methods used in other regions

of the United States.

• Species richness values found in the Pilot

Study were somewhat lower than those found

in the Southeast, higher than in Colorado,

and similar to California.

• Methods appear to be fairly repeatable across

sites, but some differences between observers emphasized that good training and quality-assurance checks are needed to achieve

a good representation of all species present.

• Results can be used to evaluate biological

effects of deteriorating air quality after a regional air-quality model is implemented, as

has been done in other regions.

SONGBIRD HABITAT INDICATOR3

Populations of many songbird species are

strongly influenced by local forest structure,

which affects microclimate, availability of foraging and nesting sites, and risk of predation.

In addition, because some forest birds are sensitive to the size and shape of forest stands,

their presence or absence can reflect habitat

quality at broader scales. Songbird communities can thus act as indicators of the effects

of forest disturbance.

During the summer of 1994, songbird surveys were conducted in conjunction with vegetation measurements on 60 study sites in the

Cascade Range of western Oregon and Wash2The eight most common species and their percentage

occurrence across 25 plots were Hypogymnia

enteromorpha, 60%; H. inactiva, 52%; H. physodes,

72%; Parmelia sulcata, 72%: Platismatia glauca, 80%; P.

herrei, 52%; Ramalina farinacea, 52%; and Usnea spp.,

3Adapted from: Cooperative Agreement Report: Wildlife

habitat indicator-Pacific Northwest Pilot Study Report.

Grant E. Canterbury and Thomas E. Martin, Montana

Cooperative Wildlife Research, University of Montana,

Missoula, MT. 1995. 11 p.

ington. Forests on these study sites were dominated by Douglas-fir and western hemlock.

The goals of this study were to collect data on

bird communities along a forest disturbance

gradient, develop habitat models to predict bird

community composition from vegetation parameters measured by Forest Health Monitoring crews, and test bird survey methods that

had previously been used successfully in

southeastern pine forests.

Four 50-meter-radius bird survey plots were

established at each site. Plot centers were 492

feet apart, covering an area of about 15 acres,

so the probability of detecting the same individual birds on more than one plot was low.

Measurements included number and species

of birds seen within each plot, estimated

canopy cover, shrub density, understory vegetation, and sapling and tree data. Sites

ranged from recent clearcuts to old-growth forests. A recorder conducted 20-minute bird

surveys at each plot between 6:00 and 10:00

AM, except during rainy or windy weather

which could interfere with detection of birds.

Because songbirds are easily surveyed and

show a variety of responses to forest habitat

structure, the species on a site can be used to

indicate the effects of forest disturbance on

bird communities. In the Pacific Northwest,

two groups of 16 disturbance-sensitive species

and 16 disturbance-tolerant species were identified from the ornithological literature (table

5-7). Each group responds primarily to major

forest disturbances such as clearcutting or

agricultural clearing rather than relatively minor disturbances such as ground fires and

selective cutting. Bird species intermediate in

habitat preference between disturbed and

mature forests were not assigned to either

group.

A Bird Community Index indicating the degree to which forest bird communities are altered by disturbance was developed from a

modified ratio of species abundance in the two

disturbance groups. The Bird Community Index was strongly influenced by vegetation characteristics on the study plots. About two-thirds

of the variability in Bird Community Index val-
ues was explained by a model including two

vegetation variables: deciduous and coniferous

canopy cover.

This study indicates that the field methods

used to survey songbirds and their habitat in

the southeastern United States also work in

the Pacific Northwest. A preliminary model

now exists to use Forest Health Monitoring

vegetation data to predict Bird Community

Index values for a stand. Thus, local habitat

structure can indicate whether bird communities should be dominated by species typical

of mature forests or those typical of disturbed,

early-successional habitat. These predictions

can be checked in the field against actual bird

communities to validate the model and determine whether other factors such as climate or

regional fragmentation of forests are also affecting bird populations.

CONCLUSIONS

Limited baseline data from forest health

detection monitoring now exist for Douglas-fir

habitats in 13 Oregon and 12 Washington Pilot Study plots sampled west of the Cascade

Range in the summer of 1994. Cooperators in

both states learned regular and quality-control protocols needed to remeasure these plots

and start statewide future operational measurements. All indicator measurements were

successfully completed with field methods

tested in 18 states, including California, since

1990. The total Pilot Study data set is small,

and interpretations must be used with caution.

Seedling and lichen ground-cover percentages (1 to 4%) were similar in Pilot Study and

about 200 California plots sampled in 1992-

95. Wetter environments and older stands in

the Northwest probably produced higher

ground percentages of ferns (18%), mosses

(35%), and shrubs (41%) plus more pole- and

sawtimber-sized trees. Most Pilot Study saplings had either good or average vigor, indicating good general health; some differences were

found between hardwood and softwoods. More

than 95% of all Pilot Study trees had good

crown ratings as shown by normal foliage

transparency, good to average crown density,

and little severe dieback. Differences in Pilot

Study and California crown ratings were minimal. Similarly, about 80% of sampled individuals across all three states had no damage

symptoms. Conks, broken tops and branches,

and decay indicators were the most common

damage classes.

Forest canopies throughout the Northwest

have many large dead and live trees. Such

trees were successfully tallied in large full-hectare (2.47-acre) plots but not in small subplots.

Remeasurement and future work in Pacific

Coast states will require using larger plots.

Vegetation structure data were collected for

four strata in all plots. The greatest number

of individuals and species were tallied in those

strata (1 and 2) nearest the ground. Lichens

were found in all plots; the average number of

macrolichens per plot was 15. A songbird

habitat study produced a model that can use

vegetation structure data from Forest Health

Monitoring plots to predict whether expected

birds will be typical of mature or disturbed forest types.

Table 5-7—Songbird and habitat relations in Douglas-fir ecosystems

Disturbance tolerant Disturbance sensitive

Dark-eyed junco Hermit warbler

MacGillivray's warbler Townsend's warbler

Rufous hummingbird Winter wren

American robin Chestnut-backed chickadee

Spotted towhee Pacific-slope flycatcher

Orange-crowned warbler Golden-crowned kinglet

House wren Red-breasted nuthatch

Black-headed grosbeak Steller's jay

Northern flicker Hammond's flycatcher

Song sparrow Varied thrush

White-crowned sparrow Hairy woodpecker

Willow flycatcher Gray jay

Olive-sided flycatcher Pileated woodpecker

Fox sparrow Red-breasted sapsucker

Lazuli bunting Red crossbill

Warbling vireo Brown creeper
CHAPTER 6. THE FUTURE OF OREGON AND

WASHINGTON FOREST HEALTH

People, as part of the natural environment,

have always used forests for their needs. These

needs have changed over the years, from generation to generation, and will change in the

future. And, at any one time, different uses

will be championed by different people. What

is perceived to be healthy, or not, may differ

between users. But no matter what the forests

are used for, they can be considered healthy

when disturbance agents, such as fire, insects,

and pathogens, remain within limits set by the

variability of natural ecosystems. Put another

way, forest health is the condition where disturbances not only do not threaten management objectives but work to maintain desired,

sustainable ecosystems.

Management, monitoring, research, and

public education are the keys to restoring,

maintaining, and improving forest health.

• Management, or manipulation of the forest

by various practices, is a valuable tool to help

reach a desired outcome within a specified

period. A variety of management options to

improve forest health in Oregon and Washington are described below.

• Monitoring is necessary to establish initial

forest conditions (the "baseline") and to detect changes in those conditions. During

implemention of new or untested strategies,

monitoring helps determine whether those

strategies produce the desired effect.

• Research is an ongoing need in forest management. Shifts in the focus from stand management to watershed and river basin management require new understanding of the

relations between forest organisms and how

management practices might affect these organisms individually and collectively over entire landscapes.

• Public education and educational programs

are needed to promote understanding of the

complexities of forest health and their relations to forest resources, uses, and management activities.
EAST OF THE CASCADES

Healthy or not?—Forest conditions in eastern Oregon and Washington have been steadily

changing for more than 100 years. Many disturbances in forest stands have altered frequencies or intensities compared to historical

ones, often outside the natural range of variation. Much of the change in disturbance regimes is due to fire suppression and selective

harvesting in the last century. Both practices

have resulted in significant changes in the distribution and structure of forest vegetation:

more true fir and Douglas-fir on low-elevation

sites where pines and larch formerly predominated, many overstocked mixed conifer and

pine stands, and more multistoried stands.

Key differences between historical and present

disturbance patterns are described below:

• Outbreaks of defoliating insects, such as

western spruce budworm and Douglas-fir

tussock moth, are now larger, more intense,

and more frequent.

• Bark beetle mortality, associated with tree

stress and overstocked stands, is more prevalent.

• Drought periods in the late 1980s and early

1990s, coupled with overstocking, contributed to increased susceptibility to insects,

diseases, and fire.

• Many root diseases and dwarf mistletoes are

more widespread and destructive because of

changes in forest structure and past harvest

practices.

• Fire is less frequent now but much more devastating on lower elevation, dry sites. The fire

hazard on these sites is higher because of fuel

buildup.

Prescribed fire reduces fuels and thins the stand by killing some of the smaller and more firesusceptible tree species.
Solutions—Although the current forest conditions are accepted as "normal" by many, we

believe these east-side forests are unhealthy

and in need of renewal and restoration. Resource managers and land owners have several options for managing their forests to

achieve long-term forest health. Prescriptions

for harvest, stand improvement, riparian restoration, or wildlife enhancement can be tailored to improve forest health and, at the same

time, to achieve resource management objectives. There are a number of ways to return

sites to historical, or other desirable, conditions

to reduce their susceptibility to fire, insects,

pathogens, and drought:

• Thin stands to reduce competition, stress,

and bark beetle susceptibility.

• Harvest certain species such as lodgepole

pine to create a mosaic of age classes across

the landscape to prevent widespread outbreaks of bark beetles.

Design site-specific regeneration (natural or

planted) to promote desired species composition.

Keep in mind the effects that various activities (such as thinning, harvest, or replanting

certain species) will have on root diseases and

dwarf mistletoes.

1 Reduce fuel loading to decrease destructive,

stand-replacing fires. Once fuels are reduced

to manageable amounts, prescribed fire can

be used more safely and effectively.

1 Introduce prescribed fire that mimics natural light ground fires to maintain a low fuel

load; remove fire-susceptible species such as

Douglas-fir and true fir; and use fire to regenerate species such as larch or quaking

aspen that depend on fire or other disturbance to create appropriate seedbeds or

stimulate root sprouting.
Reducing Bark Beetle Damage in eastern Oregon and Washington. When

sufficient susceptible host material is available, bark beetle populations can become

primary pests, capable of killing otherwise healthy host trees. Outbreaks subside

when suitable host material is depleted. We recommend the following actions to

minimize bark beetle damage:

• Keep trees well-spaced and, therefore, vigorous; thinning changes stand

structure, disrupts beetle movement, and increases vigor in residual trees.

• Thin or clearcut lodgepole pine stands approaching 60 to 80 years of age

or 8 to 10 inches in diameter. A long-term strategy for reducing damage

from mountain pine beetle in lodgepole pine is to maintain a mosaic of age

classes, preventing the whole landscape from being covered with uniform,

highly susceptible stands at the same time.

• Remove or destroy trees that currently contain bark beetles before the

spring after the initial attack. Trees that have been killed by bark beetles

generally do not perpetuate risk of additional insect or disease damage to

the stand after the first year.

Quaking aspen needs fire to successfully regenerate from the roots of burned, killed trees.
Minimizing effects from defoliators. Factors that favor survival of western spruce

budworm, Douglas-fir tussock moth, and hemlock looper include stands with a predominance of host species, mature stands with large crowns and many nutritious reproductive

buds, and a multilayered canopy with host species in both the overstory and understory.

We recommend the following actions to improve stand and host tree resistance to defoliators:

• Maintain a diversity of seral forest stages with mixed host and nonhost species.

• Where feasible, convert mixed stands of Douglas-fir, true fir, and associated

species threatened by defoliators to stands composed primarily of Ponderosa pine,

western white pine, and smaller proportions of western larch and Douglas-fir.

• Maintain or manage for reasonable stocking density.

• Maintain or manage for low vertical diversity.

WEST OF THE CASCADES

Healthy or not?—Natural forests in western Oregon and Washington have been reduced

and fragmented by urbanization and logging

in the last half-century. Widespread harvest

and replanting have reduced diversity of species and structure in many areas. But, unlike

in east-side forests, changes in natural disturbance regimes are neither as widespread nor

as dramatic. The continued good health of

west-side forests is, however, still threatened

by the following changes:

• Incidence and damage by native forest pathogens, particularly root diseases, have increased because of past forest management

practices.

• Introductions of exotic pests have risen dramatically over the past century with increased

commerce, travel, and new people moving to

the Northwest.

• Air pollution has worsened in the Willamette

Valley and Puget Sound areas with increased

population and industry. Ozone and other

pollutants can damage forests near and far

from pollutant sources.

• Periods of drought have contributed to susceptibility of trees to attacks by insects and

pathogens.

• Stresses on urban trees from air pollution,

mechanical injury, and poor maintenance,

have increased in many cities and towns.

• Fire, wind, and disease are hazards to trees,

people, and homes in the urban-forest interface.

Solutions—Improving forest health in western Oregon and Washington can be approached

from two directions: maximizing forest management options and minimizing urban impacts.

In forested areas on the west side, resource

managers and land owners have several options

for managing their forests to achieve long-term

forest health. Although restoration efforts over

large areas are not usually called for, changes

at a smaller scale can be beneficial. Some strategies for forest health improvement in western

Oregon and Washington include the following:

• Shift stands from single species to multiple

species to reduce insect outbreaks and proliferation of diseases. Tradeoffs between maximizing timber production (traditionally with

even-aged, single-species plantations) and

minimizing insect and disease damage must

be examined.

• Replant harvested or restored areas with seedlings grown from local seed sources or use

natural regeneration. Severity of diseases such

as Swiss needle cast is much less when trees

are adapted to the site.

• Maintain a mosaic or mix of species and age

classes, preventing the whole landscape from

being dominated by uniform, highly susceptible stands.
Is root disease more common now than in the past? In general, root diseases were

probably less frequent and in smaller centers in the past than currently. Why?

• Harvesting root-diseased trees left infected roots in the ground and

increased chances for contact with roots of healthy trees.

• Regeneration of root-disease-susceptible species has

been encouraged.

• Compaction on sensitive soils has reduced vigor of residual trees,

leaving them more vulnerable to armillaria root disease.

• Fire suppression has favored root-disease-susceptible species.

• Injury of roots and lower stems during harvest operations can attract

insects that spread black stain root disease in susceptible hosts.

• Creation of more stumps has resulted in more habitat for some root

disease fungi.

Insect and disease damage

can often be reduced by

planting seedlings of resistant

or tolerant species and using

local seed sources.
The effects of people on west-side forests can

be lessened several ways. As the population

in the Northwest grows, the following remedial

or preventive actions become ever more crucial to forest health:

• Reduce air pollution through a variety of

strategies and new technology so that production of ozone and other pollutants that damage forests can be reduced or, at the very least,

not increased.

• Maintain programs to monitor and eradicate exotic pests, and to prevent new introductions. Where exotics already are established,

prevention activities, such as the resistance

breeding program for white pine blister rust,

are crucial to the survival of native tree species.

• Plant and care for trees and other vegetation in urban areas. Use species adapted to

the local climate and able to withstand stresses

associated with an urban environment.

• Manage for hazards such as fire, decay,

and root disease in urban-forest interfaces.

The white pine blister rust resistance breeding program in

Cottage Grove, Oregon, inoculates thousands of white pine

and sugar pine seedlings with blister rust to find a few

resistant individuals that can be propagated.

Urban tree selection and care are important to

ensure longevity and safety of community trees.

SOUTHWEST OREGON

Conditions and changes in disturbance patterns over the past century

in southwest Oregon share similarities with both eastern and western

Oregon and Washington. The effects

of fire suppression and past harvesting influenced and changed current

vegetation conditions, much as they

did east of the Cascades. Many sites

are overstocked, prone to insect outbreaks, and have high fire hazard. A

period of drought in the late 1980s

and early 1990s, coupled with overstocking, contributed to susceptibility to insects, disease, and fire. Exotic diseases, such as white pine

blister rust and Port-Orford-cedar

root disease, have had significant effects on five-needled pines and PortOrford-cedar, respectively, and their

management. Strategies for improving forest health are similar to those

for eastern and western Oregon and

Washington.
Restoration of five-needle pines. Where western white pine, sugar pine, and

whitebark pine are being killed by blister rust and bark beetles, several options are

available to improve their vigor and resistance:

• Density management treatments, such as thinning or underburning,

increase vigor and make trees less prone to bark beetle attack, particularly in stands with large sugar pines.

• Underburning to maintain clear ground for seed hiding by birds is

essential for whitebark pine regeneration.

• Rust-resistant western white pine and sugar pine is available to be

planted on sites where risk of blister rust infection is high.

THE FUTURE

Citizens, forest owners, and resource managers must all become active to solve forest

health problems in Oregon and Washington.

Without cooperation and interaction among groups with

diverse and opposing viewpoints, future needs and desires for products and services from regional forests

will not be met.

East of the Cascades, the

risks of uncontrollable,

stand-replacing wildfires

and widespread insect outbreaks are very great unless

fuels and tree densities are

reduced.

West of the Cascades, the continued introduction of exotic insects, diseases, and

plants threaten the existence of native forests and, without continual vigilance,

chances of establishment and spread are

much greater. Air pollution, unless controlled and reduced, will affect increasing

numbers of forest species, influencing their

ability to grow and reproduce.

On both sides of the Cascades, incidence and severity

of many native insects and

diseases is closely linked to

forest management; awareness of the effects of various

activities on insects and diseases is essential to achieving

desired forest conditions.

Forest management, forest

health monitoring, research,

and public education are the

tools needed to create and maintain the forests that are so important to the people of

Oregon and Washington.
SELECTED REFERENCES

Agee, James K. 1993. Fire ecology of Pacific Northwest forests. Washington, DC: Island Press. 493 p.

Bailey, Robert G.; Avers, Peter E.; King, Thomas; McNab, W. Henry, eds. 1994. Ecoregions of the

United States (map). Washington, DC: U.S. Geological Survey. Scale 1:7,500,000; colored. Accompanied

by a supplementary table of map unit descriptions compiled and edited by McNab, W. Henry, and Bailey,

Robert G. Prepared for the U.S. Department of Agriculture, Forest Service.

Benedict, Warren V. 1981. History of white pine blister rust control—a personal account. Rep. 355. Washington, DC: U.S. Department of Agriculture, Forest Service. 47 p.

Busing, Richard T.; Liegel, Leon H.; LaBau, V.J. [In press]. Overstory mortality as an indicator of forest

health in California. Environmental Monitoring and Assessment. 85 p.

Dale, John. 1996. California forest health report (in preparation). FPM Rep. San Francisco, CA: U.S.

Department of Agriculture, Forest Service.

Franklin, J.F.; Dryness, C.T. 1988. Natural vegetation of Oregon and Washington. Corvallis, OR: Oregon

State University Press. 452 p.

Hessburg, Paul F.; Mitchell, R.G.; Filip, G.M. 1994. Historical and current roles of insects and pathogens

in eastern Oregon and Washington forested landscapes. Gen. Tech. Rep. PNW-GTR-327. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 72 p.

Liebhold, Andrew M.; MacDonald, William L.; Bergdahl, Dale; Mastro, Victor C. 1995. Invasion by

exotic forest pests: a threat to forest ecosystems. Forest Science Monograph 30. 49 p.

Liegel, Leon H.; Busing, Richard T.; LaBau, V.J. 1996. Evaluating overstory conditions to assess forest

health in California. In: Proceedings of the Society of American Foresters national convention; 1995 Oct.

28-Nov. 1; Portland, ME. Bethesda, MD: Journal of American Foresters: 424-425.

Liegel, Leon H.; Busing, Richard T.; Solano, Samuel. 1996. Forest health monitoring (FHM) activities in

the WEST, 1992-1995. In: Proceedings of the California Forest Pest Council, 44th Annual Meeting; 1995

Nov. 15-16; Rancho Cordova, CA. Sacramento, CA: Department of Forestry and Fire Protection: xi-xix.

Mavity, Erika; Stratton, Daniel; Berrang, Paul. 1995. Effects of ozone on several species of plants which

are native to the Western United States. Report. Dry Branch, Georgia: U.S. Department of Agriculture,

Forest Service, Center for Forest Environmental Studies. 61 p.

McNab, W. Henry; Avers, Peter E., comps. 1994. Ecological subregions of the United States: section descriptions. Admin. Publ. WO-WSA-5. Washington, DC: U.S. Department of Agriculture, Forest Service. 267 p.

Sprengel, Keith, comp. 1995. Forest insect and disease conditions, Pacific Northwest Region, 1994. R6-FIDTP-06-95. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 64 p.

Twardus, Dan; Miller-Weeks, Margaret; Gillespie, Andy. 1995. Forest health assessment for the Northeastern Area, 1993. Tech. Rep. NA-TP-01-95. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Area. 61 p.

U.S. Congress, Office of Technology Assessment. 1993. Harmful non-indigenous species in the United

States. Admin. Publ. OTA-F-565. Washington, DC. 391 p.

U.S. Department of Agriculture, Forest Service. 1996. Air resource management: what we have been doing.

R6-NR-TP-14-96. Portland, OR. U.S. Department of Agriculture Forest Service, Pacific Northwest Region.

Wickman, Boyd E. 1992. Forest health in the Blue Mountains: the influence of insects and diseases. Gen.

Tech. Rep. PNW-GTR-295. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 15 p.
APPENDIX A—COMMON AND SCIENTIFIC NAMES

The common and scientific names of the trees, diseases, and insects mentioned in this report are listed in alphabetical order by common name. An asterisk (*) indicates an exotic (nonnative) species.

Trees:

Alaska yellow-cedar

American elm

Bigleaf maple

Black cottonwood

California black oak

Chinkapin

Douglas-fir

Engelmann spruce

Grand fir

Hybrid poplar

Jeffrey pine

Lodgepole pine

Mountain hemlock

Noble fir

Oregon ash

Oregon white oak

Pacific dogwood

Pacific madrone

Pacific silver fir

Pacific yew

Ponderosa pine

Port-Orford-cedar

Quaking aspen

Red alder

Sitka spruce

Subalpine fir

Sugar pine

Tanoak

Western hemlock

Western larch

Western redcedar

Western white pine

Whitebark pine

White fir

Willow

Chamaecyparis nootkatensis

Ulmus americana

Acer macrophyllum

Populus trichocarpa

Quercus kelloggii

Castanopsis chrysophylla

Pseudotsuga menziesii

Picea engelmanii

Abies grandis

Populus spp.

Pinus jeffreyi

Pinus contorta

Tsuga mertensiana

Abies procera

Fraxinus latifolia

Quercus garryana

Cornus nuttallii

Arbutus menziesii

Abies amabalis

Taxus brevifolia

Pinus ponderosa

Chamaecyparis lawsoniana

Populus tremuloides

Alnus rubra

Picea sitchensis

Abies lasiocarpa

Pinus lambertiana

Lithocarpus densiflorus

Tsuga heterophylla

Larix occidentalis

Thuja plicata

Pinus monticola

Pinus albicaulis

Abies concolor

Salix spp.
Diseases:

Annosus root disease

Armillaria root disease

Black stain root disease

* Dogwood anthracnose

Douglas-fir dwarf mistletoe

* Dutch elm disease

Laminated root rot

Larch dwarf mistletoe

Lodgepole pine dwarf mistletoe

* Melampsora leaf rust (hybrid poplar)

Mountain hemlock dwarf mistletoe

* Port-Orford-cedar root disease

Schweinitzii root and butt rot

Swiss needle cast

Tomentosus root rot

Western dwarf mistletoe (ponderosa pine]

Western hemlock dwarf mistletoe

White fir dwarf mistletoe

* White pine blister rust

Insects:

* Balsam woolly adelgid

Douglas-fir beetle

Douglas-fir engraver

Douglas-fir tussock moth

Fir engraver

Forest tent caterpillar

* Gypsy moth (European or Asian)

Hemlock looper

Hemlock sawfly

Madrone leafminer

Mountain pine beetle

Oak looper

Pandora moth

Ponderosa pine cone beetle

* Satin moth

Sitka spruce weevil

Spruce beetle

Western pine beetle

Western spruce budworm

Heterobasidion annosiim

Armillaria ostoyae

Leptographium wagneri

Discula destructiva

Arceuthobium douglasii

Ophiostoma ulmi

Phellinus weirii

Arceuthobium laricis

Arceuthobium americanum

Melampsora larici-populina,

M. medusae f.sp. deltoidae

Arceuthobium tsugense f.sp.

mertensianae

Phytophthora lateralis

Phaeolus schweinitzii

Phaeocryptopus gaumannii

Ionotus tomentosus

Arceuthobium campylopodum

Arceuthobium tsugense f.sp. tsugense

Arceuthobium abietinum f.sp. concoloris

Cronartium ribicola

Adelges piceae

Dendroctonus pseudotsugae

Scolytus unispinosus

Orgyia pseudotsugata

Scolytus ventralis

Malacosoma disstria

Lymantria dispar

Lambdina fiscellaria lugubrasa

Neodiprion tsugae

Marmara arbutiella

Dendroctonus ponderosae

Lambdina fiscellaria

Coloradia pandora

Conophthorus ponderosae

Leucoma salicis

Pissodes sitchensis

Dendroctonus rufipennis

Dendroctonus brevicomis

Choristoneura occidentalis
APPENDIX B—COUNTIES IN OREGON AND WASHINGTON
APPENDIX C—1995 COOPERATIVE AERIAL SURVEY RESULTS

Figure I—Reporting areas for the 1995 Cooperative Aerial Survey in Oregon and Washington.

1

2

3

4

5

6

7

8

9

10

II

12

14

99

NF:

IR =

NP

Key:

Deschutes NF

Fremont NF

Gifford Pinchot NF

Malheur NF

Mt. Baker-Snoqualmie NF

Mt. Hood NF

Ochoco NF

Okanogan NF

Olympic NF

Rogue River NF

Siskiyou NF

Siuslaw NF

Umatilla NF

Makah IR

= National Forest

Indian Reservation

= National Park

15

16

17

18

20

21

22

23

24

25

26

27

28

Umpqua NF

Wallowa-Whitman NF

Wenatchee NF

Willamette NF

Winema NF

Colville NF

Kaniksu NF

Colville IR

Umatilla IR

Quinalt IR

Spokane IR

Warm Springs IR

Yakama IR

29

30

31

34

35

36

38

39

49

51

53

54

55

Northwest Oregon

Central Oregon

Coos-Douglas

Puget Sound

Northeast Washington

Northwest Washington

Southwest Washington

Glenwood

Lookout Mtn.

Crater Lake NP

Mt. Rainier NP

Olympic NP

N. Cascades NP
Table I—1995 cooperative aerial survey results, arranged by damage agent and state

Insect species-host

Area not flown

Area not flown

Balsam woolly adelgid

Bear

Bear

Black pineleaf scale

Blister rust

Budmoth on Douglas-fir

Cytospora canker

Douglas-fir beetle

Douglas-fir beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Douglas-fir beetle engraver

Douglas-fir tussock moth

Dying hemlock

Fir engraver

Fir engraver

Fir engraver

Fire

Fire

Flatheaded woodborer

Larch casebearer

Larch casebearer

Larch needle cast

Lodgepole needle cast

Lodgepole needle cast

Maple discoloration

Mountain pine beetle, lodgepole pine

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, sugar pine

Mountain pine beetle, sugar pine

Mountain pine beetle, w. white pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Mountain pine beetle, whitebark pine

Needleminers on Douglas-fir

Needleminers on lodgepole pine

Oregon pine ips

Oregon pine ips

Pacific Madrone decline

Port Orford cedar root disease

Root disease

State

Oregon

Washington

Washington

Oregon

Washington

Oregon

Washington

Oregon

Oregon

Idaho

Oregon

Washington

Oregon

Washington

Oregon

Washington

Idaho

Oregon

Washington

Oregon

Washington

Oregon

Oregon

Washington

Washington

Oregon

Washington

Washington

Oregon

Washington

Idaho

Oregon

Washington

California

Oregon

Oregon

Washington

Oregon

Washington

Oregon

Oregon

Oregon

Washington

Washington

Oregon

Oregon

Acres

115682

814274

14380

740

27225

264

5731

1226

366

425

37648

6128

139

618

2931

51

14

534170

39476

1879

174

3396

387

1434

487

387

1434

484

104891

123290

14

128567

58534

19

489

424

16508

21

7541

7391

6485

4417

1275

68

1885

1054

# Trees

0

0

12231

755

25454

0

0

0

1466

235

22004

3917

62

355

0

0

5

429145

30323

0

0

4533

0

0

0

0

0

0

396346

346037

6

101666

52005

8

275

342

12047

5

1418

0

0

3901

1074

0

4237

0

CONTINUED
Insec

t species-host

Root disease

Satin moth

Silver fir beetle

Spruce aphid

Spruce aphid

Spruce beetle

Spruce beetle

Water

Water

Western balsam bark beetle

Western balsam bark beetle

Western balsam bark beetle

Western pine beetle

Western pine beetle

Western pine beetle

Western pine beetle, small trees

Western pine beetle, small trees

Western spruce budworm

Western spruce budworm

Wind

State

Washington

Washington

Washington

Oregon

Washington

Oregon

Washington

Oregon

Washington

Idaho

Oregon

Washington

Idaho

Oregon

Washington

Oregon

Washington

Oregon

Washington

Washington

Acres

227

4548

7628

841

4874

4679

10

1260

23

6858

6423

221

34100

18021

1550

26881

14873

175104

1038

# Trees00

47000

1486

546100

20

5484

3662

25

18572

8993

3395

15521000
Table 2—1995 cooperative aerial survey results, for insects only, arranged by state, reporting area,

and insect

State

California

Idaho

Idaho

Idaho

Idaho

Idaho

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Reporting Area

Rogue River National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Central Oregon

Central Oregon

Central Oregon

Central Oregon

Central Oregon

Coos-Douglas

Coos-Douglas

Coos-Douglas

Coos-Douglas

Coos-Douglas

Crater Lake National Park

Crater Lake National Park

Crater Lake National Park

Deschutes National Forest

Deschutes National Forest

Deschutes National Forest

Deschutes National Forest

Deschutes National Forest

Deschutes National Forest

Fremont National Forest

Fremont National Forest

Fremont National Forest

Fremont National Forest

Fremont National Forest

Fremont National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Malheur National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Insect species-host

Mountain pine beetle, sugar pine

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Western balsam bark beetle

Western pine beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Oregon pine ips

Western pine beetle

Douglas-fir beetle

Fir engraver

Flatheaded woodborer

Mountain pine beetle, ponderosa pine

Mountain pine beetle, sugar pine

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Western pine beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Needleminers on lodgepole pine

Western pine beetle

Douglas-fir beetle

Douglas-fir tussock moth

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Oregon pine ips

Spruce beetle

Western pine beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Oregon pine ips

Acres

19

425

14

14

2 3

221

295

31

1674

1254

12

81

61

8

7

15

135

1243

440

40

17639

77747

7237

42

1097

6

311424

7906

21592

5863

7527

826

2931

2916

2258

7314

163

87

2149

424

8

10299

221

10435

228

114

# Trees

8

235

5

6

20

25

132

15

1199

453

5

70

125

10

10

16

50

368

286

37

29054

322592

6489

100

530

5

267409

40192

12539

0

5511

889

0

2053

1238

8930

155

50

2405

351

5

8647

235

8359

120

150
State

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Reporting Area

Mt. Hood National Forest

Mt. Hood National Forest

Mt. Hood National Forest

Northwest Oregon

Northwest Oregon

Northwest Oregon

Ochoco National Forest

Ochoco National Forest

Ochoco National Forest

Ochoco National Forest

Ochoco National Forest

Ochoco National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Rogue River National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siskiyou National Forest

Siuslaw National Forest

Siuslaw National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla Indian Reservation

Umatilla Indian Reservation

Umatilla Indian Reservation

Umatilla Indian Reservation

Umpqua National Forest

Umpqua National Forest

Umpqua National Forest

Insect species-host

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Douglas-fir beetle

Fir engraver

Spruce aphid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Oregon pine ips

Western pine beetle

Western pine beetle, small trees

Douglas-fir beetle

Fir engraver

Flatheaded woodborer

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, sugar pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Oregon pine ips

Western pine beetle

Western pine beetle, small trees

Douglas-fir beetle

Fir engraver

Flatheaded woodborer

Mountain pine beetle, ponderosa pine

Mountain pine beetle, sugar pine

Oregon pine ips

Western pine beetle

Western pine beetle, small trees

Budmoth on Douglas-fir

Douglas-fir beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Needleminers on Douglas-fir

Oregon pine ips

Spruce beetle

Western balsam bark beetle

Western pine beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Western pine beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Acres

462

46

14873

263

82

8

1812

7041

26806

433

12254

353

54

60398

3309

290

3134

248

14

21

713

3734

1077

37

2555

79

143

186

12

1063

74

1226

138

19045

3632

7712

2580

1507

59

5003

2222

558

40

345

147

115

146

135

# Trees

315

30

0

319

55

0

3179

3047

18466

225

4644

376

55

44079

4463

673

3078

119

10

5

1755

2946

2914

69

1590

60

160

120

35

775

75

0

205

8455

1959

7557

0

988

25

3352

429

223

25

540

25

110

119

115
State

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Oregon

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Reporting Area

Umpqua National Forest

Umpqua National Forest

Umpqua National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Wallowa-Whitman National Forest

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Warm Springs Indian Reservation

Willamette National Forest

Willamette National Forest

Willamette National Forest

Willamette National Forest

Willamette National Forest

Willamette National Forest

Willamette National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Winema National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Insect species-host

Mountain pine beetle, sugar pine

Mountain pine beetle, w. white pine

Western pine beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Larch casebearer

Lodgepole needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Needleminers on Douglas-fir

Oregon pine ips

Spruce beetle

Western balsam bark beetle

Western pine beetle

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Oregon pine ips

Western pine beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, w. white pine

Oregon pine ips

Western pine beetle

Black pineleaf scale

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, sugar pine

Mountain pine beetle, w. white pine

Needleminers on lodgepole pine

Western pine beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Larch casebearer

Lodgepole needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Acres

35

13

11

12876

9

3279

387

387

278

14645

12

4811

185

4728

1855

2432

263

4480

12190

740

5

32

134

469

122

1016

2225

93

4

8

264

211

107888

1201

26783

5

17

622

848

207

242

7194

616

616

18527

11984

1616

57

# Trees

19

10

10

7207

7

1594

0

0

151

20169

5

0

30

1411

2132

566

123

3946

28219

471

5

90

40

495

50

770

1271

87

20

5

0

30

64290

1374

13699

1

5

0

366

120

165

5213

0

0

18734

8837

711

50
State

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Reporting Area

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville National Forest

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Colville Indian Reservation

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Gifford-Pinchot National Forest

Glenwood

Glenwood

Glenwood

Glenwood

Glenwood

Glenwood

Glenwood

Glenwood

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Kaniksu National Forest

Insect species-host

Oregon pine ips

Satin moth

Silver fir beetle

Spruce beetle

Western balsam bark beetle

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Oregon pine ips

Satin moth

Silver fir beetle

Western balsam bark beetle

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Oregon pine ips

Silver fir beetle

Western balsam bark beetle

Western pine beetle

Western spruce budworm

Douglas-fir beetle

Fir engraver

Mountain pine beetle, ponderosa pine

Oregon pine ips

Spruce beetle

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Douglas-fir beetle

Fir engraver

Larch casebearer

Lodgepole needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Spruce beetle

Acres

485

6 4 3

517

94

2901

3082

779

4034

113

12

1849

5035

10495

210

949

182

146

3273

632

936

1995

846

1168

7

48

145

302

61

37

196

28

15407

434

312

5454

237

39

2067

19187

29028

30

1963

120

120

2299

718

3258

77

# Trees

289

0

276

30

1648

1286

655

0

55

10

1506

6148

9644

385

0

99

75

1538

647

0

886

534

536

5

35

70

4

10

75

40

30

0

115

315

5184

130

2

911

9051

0

15

1431

0

0

2174

551

3907

20
State

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Reporting Area

Kaniksu National Forest

Kaniksu National Forest

Makah Indian Reservation

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Baker-Snoqualmie National Forest

Mt. Rainier National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

North Cascades National Park

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Northeast Washington

Nortwest Washington

Nortwest Washington

Nortwest Washington

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Insect species-host

Western balsam bark beetle

Western pine beetle

Douglas-fir beetle

Balsam woolly adelgid

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, Ponderosa pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Silver fir beetle

Spruce beetle

Western balsam bark beetle

Western pine beetle

Balsam woolly adelgid

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Larch needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Spruce beetle

Western balsam bark beetle

Western pine beetle

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Larch casebearer

Lodgepole needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Oregon pine ips

Satin moth

Western pine beetle

Western pine beetle, small trees

Douglas-fir beetle

Douglas-fir beetle engraver

Mountain pine beetle, lodgepole pine

Douglas-fir beetle

Douglas-fir beetle engraver

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Mountain pine beetle, w. white pine

Acres

124

31

8

3975

1050

137

347

332

209

454

59

26

2336

150

332

2880

57

54

447

59

69

258

274

48

99

80

160

91

61

5887

698

698

611

9842

118

129

20

1270

580

367

36

90

213

127

2656

90138

5618

1295

# Trees

150

20

5

3314

581

35

174

1534

125

260

85

20

4506

115

270

3600

80

60

235

0

150

220

155

34

55

80

75

90

65

7251

0

0

430

10687

75

125

0

821

725

292

10

159

110

65

1373

310023

4701

820
State

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Reporting Area

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Okanogan National Forest

Olympic National Forest

Olympic National Forest

Olympic National Forest

Olympic National Forest

Olympic National Forest

Olympic National Forest

Olympic National Park

Olympic National Park

Olympic National Park

Olympic National Park

Olympic National Park

Puget Sound

Puget Sound

Puget Sound

Quinalt Indian Reservation

Southwest Washington

Southwest Washington

Southwest Washington

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Spokane Indian Reservation

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Umatilla National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Insect species-host

Mountain pine beetle, whitebark pine

Oregon pine ips

Satin moth

Spruce aphid

Spruce beetle

Western balsam bark beetle

Western pine beetle

Western pine beetle, small trees

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, w. white pine

Spruce aphid

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Douglas-fir beetle

Douglas-fir beetle engraver

Mountain pine beetle, w. white pine

Fir engraver

Douglas-fir beetle

Mountain pine beetle, lodgepole pine

Spruce aphid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Oregon pine ips

Spruce beetle

Western pine beetle

Western pine beetle, small trees

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Oregon pine ips

Spruce beetle

Western balsam bark beetle

Western pine beetle

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Larch needle cast

Mountain pine beetle, lodgepole pine

Mountain pine beetle, ponderosa pine

Acres

901

55

2273

33

876

1228

1560

30

482

488

34

64

339

83

3400

34

26

1192

38

253

3

28

36

210

12

725

105

337

13

1103

6

21

208

174

791

1812

55

1472

45

22

438

455

1582

812

14706

428

1574

7418

# Trees

390

30

0

0

435

600

597

30

335

308

21

35

225

0

3110

2 5

14

755

20

195

5

10

25

171

20

0

90

410

10

1416

5

5

80

230

490

1606

120

2152

25

5

370

145

901

646

8583

0

1789

6390
State

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Washington

Reporting Area

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Wenatchee National Forest

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Yakima Indian Reservation

Insect species-host

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Oregon pine ips

Satin moth

Spruce beetle

Western balsam bark beetle

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Balsam woolly adelgid

Douglas-fir beetle

Fir engraver

Mountain pine beetle, lodgepole pine

Mountain pine beetle, Ponderosa pine

Mountain pine beetle, w. white pine

Mountain pine beetle, whitebark pine

Spruce beetle

Western pine beetle

Western pine beetle, small trees

Western spruce budworm

Acres

7746

5327

47

663

646

1160

4805

3525

132

9

22

702

4464

3915

4 3

809

469

750

1974

125567

# Trees

4964

760

75

0

325

584

2810

2678

0

5

15

1630

4706

2063

9 5

75

78

410

1505

0
APPENDIX D—THE NATIONAL FOREST HEALTH MONITORING PROGRAM

The national Forest Health Monitoring Program (often abbreviated as FHM) began in 1990

in 10 northeastern states. It was a cooperative effort between the USDA Forest Service, the

U.S. Environmental Protection Agency (EPA), state forestry agencies, and the National Association of State Foresters. Today, cooperators also include the U.S. Department of the Interior's

Bureau of Land Management, Fish and Wildlife Service, and National Park Service; the USDA

National Resource Conservation Service; and state forestry organizations in eight additional

states. The main objectives of this program are to determine the status, trends, and condition

of forests nationwide.

The national Forest Health Monitoring West Coast Administrative Region includes California, Hawaii, and Alaska plus Oregon and Washington. Operational field work began in California in 1992 when 55 forested plots were measured across the state. A different set of about 50

forested plots were measured yearly from 1993 to 1995. This complete 4-year set of data comprises the baseline condition for California forests. Each baseline year is a separate estimate

of forest conditions in the state. Remeasurement of California plots began in 1996. Another

field effort in the West Coast region was a pilot study for western Oregon and Washington

(described in chapter 5), in which 25 plots in Douglas-fir habitat were measured. Baseline

plots in Oregon and Washington will be established in 1997.
Three separate but parallel activities comprise the Forest Health Monitoring Program. In

detection monitoring, field crews measure selected biotic and abiotic features called indicators of forest condition during a baseline period. These same features are then remeasured at

yearly or other intervals. Changes between the baseline and remeasurement conditions indicate a response to natural forest change or ecosystem disturbance. The ecosystem indicators

are analogous to general blood pressure, pulse, and blood chemistry data recorded for people

in routine medical exams. Infant, juvenile, adult, and mature age groups have certain indicator values for normal health. Values outside the normal ranges indicate something is amiss

and should be checked by a medical specialist.

Evaluation monitoring begins when the cause of a significant and detected change is unknown. Activities include intensive field sampling and combined interpretations by ecologists,

entomologists, hydrologists, pathologists, silviculturists, and others. These resource specialists are like the heart, kidney, lung, and other medical experts who are asked to diagnose

blood chemistry results that fall outside of normal values or that result from traumatic injury.

Intensive site ecosystem monitoring combines knowledge from evaluation monitoring and

results from long-term watershed-scale research at a few sites with diverse forest types and

biomes typical of those found in the United States. The best example in the West is the H.J.

Andrews Experimental Forest near Blue River, Oregon, where forest research work has been

conducted since the 1940s.

Combining information from all three monitoring activities allows predicting where and how

future ecosystem changes might take place under given environmental and management conditions.
Index

101-102

forest tent caterpillar 52, 89

G

grand fir 9, 16, 25, 30, 32-

35, 37, 50, 53-56, 88

grazing 6, 9, 11, 38, 57

gypsy moth 16, 19, 62-64,

89

H

hazard tree 46-47, 61, 64

hemlock looper 9, 49-50,

82, 89

hemlock sawfly 29, 89

hybrid poplar 32, 88

I

indicators 2, 19, 21, 22, 66-

67, 70, 73-74, 76-77,

102

Intensive site ecosystem

monitoring 102

introduced pests. See exotic

pests

J

Jeffrey pine 39, 41, 88

K

Klamath Mountains 4, 39-43

L

laminated root rot 26-27,

36, 40, 47, 53, 61, 89

larch dwarf mistletoe 34,

55, 89

lichens 19-22, 30, 46, 68,

75-77

lodgepole pine 6, 10-11,25,

33, 35, 37-38, 40-41, 53,

55, 57, 80-81, 88, 92,

94-100

lodgepole pine dwarf mistletoe 35, 40, 55, 89

low temperature injury 14-

15, 31

A

air pollution 11, 19-21, 30,

46, 72, 75-76, 82, 84, 85

air quality. See air pollution

Alaska yellow-cedar 39, 88

American elm 62, 88

annosus root disease 29,

36, 38, 53-54, 89

armillaria root disease 27,

32, 36, 40, 54, 83, 89

B

balsam woolly adelgid 16,

32, 50-51, 89, 92, 97-

100

bark beetles 10,12-14,26,

32-33, 35-38, 40, 42-43,

47-48, 51, 54, 56-58, 62,

79-81, 85

basal area 69

bear damage 22, 28-29

bigleaf maple 25, 30, 45, 51,

88

bird community index. See

songbird habitat

bioindicators. See indicators

black cottonwood 30, 33,

38, 88

black stain root disease 27,

40, 83, 89

Blue Mountains 4, 13, 15,

33-38

c

California black oak 39, 88

canker diseases 31, 34

chinkapin 39, 88

crown dieback 70-71

D

defoliators 10, 32-33, 35,

49-50, 54-55, 58, 62-64,

82

detection monitoring 102

Douglas-fir 7, 9-10, 25-29,

33-36, 38-39, 43, 45,

47-49, 53-56, 67, 69,

82,88

Douglas-fir beetle 26, 35-36,

43, 47-48, 56, 89, 92,

94-100

Douglas-fir dwarf mistletoe

34-35, 40-41, 55-56, 89

Douglas-fir engraver 89

Douglas-fir tussock moth

38, 79, 82, 89, 92, 94

drought 11, 15, 26, 30-37,

39, 42-43, 47, 51-52, 56,

58, 64, 79-80, 82, 84

dwarf mistletoes 10,29,34-

35, 40-41, 49, 55-56

E

Eastern Cascades 4, 79-82

Eastern Cascades, Oregon 4,

33-38

Eastern Cascades, Washington 4, 53-58

Engelmann spruce 25, 38,

45, 53, 88

exotic pests 16-19, 29, 32,

41-43, 50, 52, 58, 62-64,

82, 84-85

F

fir engraver 35-36, 89,92,

94-100

fire 6-12, 25-26, 30, 32-41,

45, 51, 53-55, 58, 61,

76, 79-82, 84, 85, 92

fire suppression 8-10, 32-

34, 36-38, 53-55, 79, 84

fire exclusion. See fire suppression

floods 34

foliage disease 27-28, 32,

47-49, 52

foliage transparency 70-72,

77

forest health monitoring 21-

23, 66-78, 85, 101-102

Forest Health Monitoring

Program 22, 66-77,
M

madrone leafminer 52, 89

melampsora leaf rust 32, 89

mixed conifer 10, 33-37, 43,

53-56, 68, 79

Modoc Plateau 4, 33-38

monitoring. See forest health

monitoring

mortality 11-13, 67

mountain hemlock 25, 39,

41, 45, 49, 53, 88

mountain hemlock dwarf

mistletoe 41, 49, 89

mountain pine beetle 11,

37-38, 42-43, 51, 56, 57,

81, 89, 92, 94-100

N

noble fir 6, 25, 45, 88

O

Okanogan Highlands 4, 53-

58

Oregon 24-43

Oregon ash 30, 88

Oregon Coast Range 4, 25-

29

Oregon white oak 30, 32,

39, 64, 88

ozone 19-21, 30, 46, 84

P

Pacific dogwood 52, 64, 88

Pacific madrone 39, 52, 88

Pacific silver fir 25, 39, 45,

88

Pacific yew 25, 88

pandora moth 38, 61, 89

poles 68, 69

Ponderosa pine 6-7, 10, 12,

30-38, 41, 43, 53-58, 82,

88

Ponderosa pine cone beetle

32, 89

Port-Orford-cedar 18, 19,

39, 41-42, 84, 88

Port-Orford-cedar root

disease 18, 19, 41-42,

84, 89

Puget Trough 4, 45-52

Q

quaking aspen 33, 38, 39,

58, 80, 88

R

red alder 25, 30, 45, 51, 52,

88

risk rating 23

root disease 10, 12, 18-19,

26-27, 29, 32, 35-36,

40-43, 46, 53-54, 56, 58,

61, 79-80, 82-84, 93

root rot. See root disease

S

sapling crown vigor 69, 70

saplings 68-70, 72, 77

satin moth 58, 89, 93, 97-

100

sawtimber 68, 69, 77

Schweinitzii root and butt rot

54, 89

seedlings 68, 83-84

site characteristics 67-69

Sitka spruce 25, 29, 45, 88

Sitka spruce weevil 29, 89

songbird habitat 67, 74, 76-

77

Southern Cascades 4, 39-43

spruce beetle 38, 84-85, 89,

93-100

stand characteristics 68

stem decay 26, 34, 46

Subalpine fir 6, 25, 45, 54,

88

subplots 68, 73-74, 77

sugar pine 17, 25, 33, 39,

42-43, 84-85, 88, 92,

94-96

Swiss needle cast 27-28, 47-

49, 82, 89

T

true fir. See grand fir and

white fir

U

understory vegetation 22,

68-69, 76

urban forest health 60-65

V

vegetation change 6-10

vegetation structure 74, 77

w

Washington 44-58

Washington Coast Range 4,

45-52

weather 13-16, 18, 21, 33-

34, 52, 60 see also

drought, floods, low

temperature injury,

windthrow, winter wind

damage

Western Cascades 4, 82-84

Western Cascades, Oregon 4,

25-29

Western Cascades, Washington 4, 45-52

western hemlock dwarf

mistletoe 49, 89

western larch 10, 12, 33-34,

37, 53-55, 82

western pine beetle 35, 58,

89, 93-100

western redcedar 25, 28, 30,

45, 69, 88

western spruce budworm

11-13, 35, 37, 54-56, 79,

82, 89, 93, 95, 97, 100

white fir 33, 35-36, 39, 41,

43, 50, 88,

white fir dwarf mistletoe 34,

89

white pine blister rust 16-

17, 19, 29, 42, 51, 84,

89

whitebark pine 17, 25, 42,

45, 51, 53, 85, 88

Willamette Valley 4, 25-29

willow 33, 45, 88

windthrow 26-27, 34, 38,

45, 47-48, 56, 61

winter wind injury 15
Campbell, Sally; Liegel, Leon, tech. coords. 1996. Disturbance and

forest health in Oregon and Washington. Gen. Tech. Rep. PNWGTR-381. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station and Pacific Northwest

Region; Oregon Department of Forestry; and Washington Department of Natural Resources. 105 p.

The scope and intensity of disturbance by such agents as fire,

insects, diseases, air pollution, and weather in Pacific Northwest

forests suggests that forest health has declined in recent years in

many areas. The most significant disturbances and causes of tree

mortality or decline in Oregon and Washington are presented and

illustrated. We discuss the interrelations of disturbance with forest

management activities and the effect on native trees and suggest

some solutions for reducing the severity of disturbance. One chapter

reports on a forest health monitoring pilot project.

The Forest Service of the U.S. Department of

Agriculture is dedicated to the principle of multiple

use management of the Nation's forest resources for

sustained yields of wood, water, forage, wildlife, and

recreation. Through forestry research, cooperation

with the States and private forest owners, and

management of the National Forests and National

Grasslands, it strives—as directed by Congress—to

provide increasingly greater service to a growing

Nation.

The United States Department of Agriculture (USDA)

prohibits discrimination in its programs on the basis

of race, color, national origin, sex, religion, age,

disability, political beliefs, and marital or familial

status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means of communication of program information (Braille, large print, audiotape, etc.) should

contact the USDA Office of Communications at (202)

720-2791.

To file a complaint, write the Secretary of Agriculture,

U.S. Department of Agriculture, Washington, DC

20250, or call (202) 720-7327 (voice) or (202) 720-

1127 (TDD). USDA is an equal employment opportunity employer.

Pacific Northwest Research Station

333 S.W. First Avenue

P.O. Box 3890

Portland, Oregon 97208-3890