Managing for Biodiversity in Young

Douglas-Fir Forests of Western Oregon

Biological Science Report

USGS/BRD/BSR 2002-0006
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Photo credits

Front and back cover forest background: Ed Jensen

Banner photos on front cover, left to right

caterpillar (Aseptis binotata): Jeff Miller;

John Tappeiner, Pat Muir, and Joe Lint discuss forest management: Mark Reed;

lichen (Pseudocyphellaria rainierensis): Jim Riley;

thinned forest stand: Jim Riley;

Wilson’s warbler (Wilsonia pusilla): Joan Hagar

Banner photos on back cover, left to right

Pacific dogwood (Cornus nuttallii): Ruth Jacobs;

Swainson’s thrush (Catharus ustulatus): Cornell Laboratory of Ornithology, Bill Dyer;

bracken fern (Pteridium aquilinum): Joan Hagar
Managing for Biodiversity in Young

Douglas-Fir Forests of Western Oregon

Biological Science Report

USGS/BRD/BSR–2002-0006

October 2002

Patricia S. Muir

Rosanna L. Mattingly

John C. Tappeiner II

John D. Bailey

Wayne E. Elliott

Joan C. Hagar

Jeffrey C. Miller

Eric B. Peterson

Edward E. Starkey

U.S. Geological Survey

Forest and Rangeland Ecosystem Science Center

Corvallis, Oregon
Suggested citation:

Muir, P.S., R.L. Mattingly, J.C. Tappeiner II, J.D. Bailey, W.E. Elliott, J.C. Hagar, J.C. Miller, E.B. Peterson, and

E.E. Starkey. 2002. Managing for biodiversity in young Douglas-fir forests of western Oregon. U.S. Geological

Survey, Biological Resources Division, Biological Science Report USGS/BRD/BSR–2002-0006. 76 pp.
Contents

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Abstract ....................................................................................................................................................

Project Introduction .................................................................................................................................

Overview ..............................................................................................................................................

The Forest .........................................................................................................................................

The Northwest Forest Plan ...............................................................................................................

The Project ........................................................................................................................................

Forest Stand Development ...................................................................................................................

Douglas-Fir Forests in Western Oregon ..............................................................................................

History of Forest Management .........................................................................................................

Current Age-Class Distribution of Young-Growth Stands ..............................................................

Changing Forest-Management Objectives .......................................................................................

Project Objectives ....................................................................................................................................

Materials and Methods ............................................................................................................................

Project Study Area ...............................................................................................................................

Description of Study Area ................................................................................................................

Young-Growth Stands ......................................................................................................................

Old-Growth Stands ...........................................................................................................................

Project Study Stands .........................................................................................................................

Study Organisms ..................................................................................................................................

Trees, Shrubs, and Herbaceous Vegetation .....................................................................................

Epiphytic Lichens and Bryophytes ..................................................................................................

Moths ................................................................................................................................................

Birds ..................................................................................................................................................

Study Methods .....................................................................................................................................

Trees, Shrubs, and Herbaceous Vegetation .....................................................................................

Epiphytic Lichens and Bryophytes ..................................................................................................

Macrolichens on Trees and Shrubs ..............................................................................................

Macrolichens and Bryophytes on Shrubs .....................................................................................

Moths ................................................................................................................................................

Birds ..................................................................................................................................................

Study Objectives, Results, and Recommendations for Management .....................................................

Trees, Shrubs, and Herbaceous Vegetation .........................................................................................

Study Objectives ...............................................................................................................................

Major Findings .................................................................................................................................

Additional Research .........................................................................................................................

Conclusions .......................................................................................................................................

Recommendations for Management .................................................................................................

Epiphytic Lichens and Bryophytes ......................................................................................................

Macrolichens on Trees and Shrubs ....................................................................................................

Study Objectives ...............................................................................................................................

Major Findings .................................................................................................................................

Conclusions .......................................................................................................................................

Recommendations for Management .................................................................................................

Macrolichens and Bryophytes on Shrubs ...........................................................................................

Study Objectives ...............................................................................................................................

Major Findings .................................................................................................................................

Conclusions .......................................................................................................................................

Recommendations for Management .................................................................................................

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Moths ....................................................................................................................................................

Study Objectives ...............................................................................................................................

Major Findings ..................................................................................................................................

Conclusions .......................................................................................................................................

Recommendations for Management .................................................................................................

Birds ......................................................................................................................................................

Study Objectives ...............................................................................................................................

Major Findings ..................................................................................................................................

Conclusions .......................................................................................................................................

Recommendations for Management .................................................................................................

Project Conclusions ..................................................................................................................................

Common Themes ..................................................................................................................................

Proposed Thinning Guidelines .............................................................................................................

Application of Research Findings ............................................................................................................

Acknowledgments ....................................................................................................................................

Glossary of Forest Ecology and Management Terms .............................................................................

Literature Cited ........................................................................................................................................

Appendixes ...............................................................................................................................................

A. Researcher Biographies ...................................................................................................................

B. Common and Scientific Names of Vegetation Referenced in Text ...............................................

C. Taxonomy Resources .......................................................................................................................

D. Common and Scientific Names of Moth Families Referenced in Text .........................................

E. Common and Scientific Names of Birds Recorded During Surveys ..............................................

F. Recommended Resources for Additional Information ....................................................................

G. Selected Abstracts ...........................................................................................................................

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Figures

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Vegetation in western Oregon from the coast to the crest of the Cascade mountains

in 1988. (A) Young stands (<80 years old) with >70 percent conifer cover. (B) Hardwood stands with >70 percent cover and mixed vegetation. (C) Mature (>70 percent

conifers between 80 and 200 years in age) and old-growth (>70 percent conifers >200

years in age) vegetation. (D) Open areas with <70 percent green vegetation cover ............................

The area of concern for the Northwest Forest Plan in Washington, Oregon, and

northern California, delineating federal land ownership and adaptive management

areas. The Northwest Forest Plan area is the habitat range of the northern spotted owl .....................

A late-successional reserve near Triangle Lake, Oregon, northwest of Eugene,

indicating young forest over a large, contiguous expanse. Late-successional reserves

are highly variable in age and cover .....................................................................................................

Forest managers implementing the Northwest Forest Plan focus efforts on an adaptive

management process through which management activities are monitored, evaluated,

considered along with findings of ongoing research, and adjusted to increase the degree

to which they meet management objectives over time .........................................................................

R nd epresentation of forest stand development. Diagrams depict: (A) trees i unthinne

young-growth stands today, with slow growth rates and a narrow range of age, and (B)

recent findings on existing old-growth forests, which indicate that trees developed with

fast growth rates during the early years and a wide range of age ........................................................

A young forest, between 30 and 50 years in age, started following timber harvest in the

O e regon C r oast Range near Harlan. Existing old-growth forests may hav started unde

conditions t h hat differ from the dense, closed-canopy conditions of stands from whic

y . oung forests generally develop today . ................................................................................................

Stump of an old tree and disk from the stump of a young tree in the Oregon Coast

Range just west of Corvallis. Marks are set at intervals of 10 years, and indicate rapid

growth of the old tree and slower growth of the young tree during the early years ............................

Unthinned young-growth stand, approximately 20 years in age. Note the high density

of trees with little development of the understory ................................................................................

(A) A thinned site typical of those surveyed during studies that were part of the

Managing for Biodiversity in Young Forests Project and (B) old growth in the

Oregon Coast Range. The young-growth stand was thinned fairly heavily and has

developed an understory containing shrubs and conifers. The old-growth stand

supports relatively few large trees spaced widely, and an intermediate structure in

the understory. Thinning may help accelerate the development of old-growth

characteristics in dense young stands ....................................................................................................

Age-class distribution of all forest lands managed by BLM in western Oregon .................................

Age-class distribution of forest stands <80 years in age on BLM lands in

western Oregon ......................................................................................................................................

Study area in western Oregon and approximate locations of study sites surveyed

during the Managing for Biodiversity in Young Forests Project ..........................................................

Organisms in a range of habitats were sampled during the Managing for Biodiversity

in Young Forests Project. Stand types surveyed for vegetation, epiphytic lichens and

bryophytes, moths, and birds included: (A) unthinned, (B) thinned, and (C) old-growth

stands. In addition, (D) clearcut stands were surveyed for moths, and hotspots were

surveyed for epiphytic lichens and bryophytes. (E) Riparian areas and (F) hardwood

gaps were among the types of hotspots sampled ..................................................................................

Some of the interactions that occur among groups of organisms studied during the

Managing for Biodiversity in Young Forests Project ...........................................................................

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Lichens generally are grouped into three forms: (A) foliose, (B) crustose, and

(C) fruticose. The foliose and fruticose lichens together are known as macrolichens .........................

Although numerous moths are generalists and can feed on a range of vegetation

species, some are specialists and can survive only if the particular food for which

they are specialized is available. Moths shown are specialized on: (A) alder, (B)

various species of Ceanothus, . and (C) oak ..........................................................................................

Adult moths were captured at night with an ultraviolet blacklight trap. Moths were

identified, counted, and sorted into functional groups based on their food resources .........................

Swainson's thrush and Wilson's warbler were captured with mist nets. After fecal

samples were collected, the birds were released. Arthropod fragments then were sorted

from the fecal samples and identified ....................................................................................................

Typical understory vegetation in stands located in the project study area included: (A)

salal, (B) bracken fern, (C) vine maple, (D) red huckleberry, and (E) Oregon-grape .........................

(A) A lightly thinned stand in the Oregon Coast Range. (B) Ten years after thinning,

this site supports abundant sword fern and is developing understory vegetation. Results

from this study suggest that thinning promotes the development of multilayered stands ...................

Macrolichens were grouped into three functional groups: (A) forage lichens, (B)

matrix lichens, and (C) cyanolichens ....................................................................................................

Bryophytes surveyed on shrubs included: (A) moss mats, (B) moss tufts, and

(C) liverworts .........................................................................................................................................

A representative sample of the species collected during one trap night at Honey Creek

(site 20, Figure 12). Approximately 500 species (nearly 15,000 specimens) were

collected during the moth study .............................................................................................................

(A) Geometrid and (B) noctuid moths, which belong to the most abundant moth

families collected during the moth study. These two families were the most important

taxa for ecological comparisons based on abundance and species richness. Both species

shown are generalists on hardwoods .....................................................................................................

Moths were classified into functional groups based on food source. Members of these

groups included moths feeding on: (A) conifers, (B) hardwoods, (C) mixed conifers and

hardwoods, (D) detritus, and (E) herbs and grasses. Although adult moths were captured

in the traps for identification, moths in the larval stage do the feeding ...............................................

Three of the bird species surveyed during the Managing for Biodiversity in

Young Forests Project: (A) Swainson's thrush, (B) Wilson's warbler, and (C)

western tanager .......................................................................................................................................

Fragments of arthropods fed on by Wilson's warbler ...........................................................................

A thinned Douglas-fir stand with vine maple in the understory. Thinning prescriptions

need to be developed on a site-by-site basis, with consideration of stand density, age,

species composition, history, landscape context, ownership, and management objectives .................

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Tables

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Description of unthinned and thinned young-growth stands and old-growth stands

surveyed during the Managing for Biodiversity in Young Forests Project ..........................................

Summary of forest stands surveyed during the Managing for Biodiversity in Young

Forests Project .......................................................................................................................................

Herbaceous species richness (number of species) by stand type across 27 paired

unthinned and thinned young-growth stands and 17 old-growth stands, with species

unique to each stand type .......................................................................................................................

Stand-level averages for understory characteristics of 32 paired unthinned and thinned

young-growth stands and 20 old-growth stands in western Oregon .....................................................

Tree and shrub macrolichen species strongly associated with (indicators for) thinned

young-growth, old-growth, and hotspot stands in western Oregon ......................................................

Relative abundance and/or species richness of tree and shrub macrolichens in unthinned

young-growth stands compared to thinned young-growth, old-growth, and hotspot

stands in the Coast Range and Cascade mountains of western Oregon ...............................................

Relative abundance and/or species richness of shrub epiphytes in unthinned younggrowth stands compared to thinned young-growth, old-growth, and hotspot stands in

western Oregon ......................................................................................................................................

Tall-shrub epiphytes in the Coast Range and Cascade mountains of western Oregon

strongly associated with (indicators for) unthinned and thinned young-growth, oldgrowth, and hotspot stands .....................................................................................................................

Abundance of moths by family in unthinned and thinned young-growth, old-growth,

and clearcut stands in Douglas-fir forests in western Oregon ..............................................................

Species richness of moths by functional group in unthinned and thinned young-growth,

old-growth, and clearcut stands in western Oregon ..............................................................................

Abundance of moths by functional group in unthinned and thinned young-growth, oldgrowth, and clearcut stands in western Oregon ....................................................................................

Bird abundance in unthinned and thinned young-growth stands and old-growth stands

in the Oregon Coast Range between May and June, 1995 through 1997 ............................................

Arthropod abundance on understory plant species in unthinned and thinned younggrowth stands and old-growth stands in the Oregon Coast Range, averaged across

collections from 1996 and 1997 ............................................................................................................

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Conversions

Length

To convert centimeters to inches, multiply by 0.394.

To convert meters to yards, multiply by 1.094.

To convert kilometers to miles, multiply by 0.621.

Area

To convert square meters to square feet, multiply by 10.76.

To convert hectares to acres, multiply by 2.47.

Mass

To convert grams to pounds, multiply by 0.0022.

Symbols

< = less than

≤ = less than or equal to

> = greater than

≥ = greater than or equal to
Managing for Biodiversity in Young Douglas-Fir Forests

of Western Oregon

Abstract: This project addressed potential contributions of forest thinning to enhancing

biodiversity and accelerating development of old-growth characteristics in relatively young

Douglas-fir forests typical of those managed according to the Northwest Forest Plan. Studies

focused primarily on 32 paired unthinned and thinned stands and 20 associated old-growth stands

in the Coast Range and Cascade mountains of western Oregon. Data were collected on vascular

plants in most stands surveyed, and on epiphytic lichens and bryophytes, moths, and birds in

subsets of these stands. Studies assessed whether or not (1) communities of organisms differed

among stand types, (2) communities in thinned stands were more similar to those in old-growth

stands than were those in unthinned stands, (3) species diversity or abundance was related to

specific stand features, and (4) these specific stand features were shared across taxa. Results

a

 Current address: Department of Forest Resources, Oregon State University, Corvallis, Oregon 97331

b

 Current address: Northern Arizona University, P.O. Box 15018, Flagstaff, Arizona 86011

c

 Current address: Nevada Natural History Program, 1550 E. Coley Parkway, Carson City, Nevada 89706

Patricia S. Muir

Department of Botany and Plant Pathology

Oregon State University

Corvallis, Oregon 97331

Rosanna L. Mattingly

U.S. Geological Survey

Forest and Rangeland Ecosystem Science Center

777 NW 9th Street, Suite 400

Corvallis, Oregon 97330

John C. Tappeiner IIa

Department of Forest Resources

Oregon State University, and

U.S. Geological Survey

Forest and Rangeland Ecosystem Science Center

3200 SW Jefferson Way

Corvallis, Oregon 97331

John D. Baileyb

Department of Forest Science

Oregon State University

Corvallis, Oregon 97331

Wayne E. Elliott

U.S. Department of the Interior

Bureau of Land Management

P.O. Box 10226

Eugene, Oregon 97440

Joan C. Hagar

Department of Forest Science

Oregon State University

Corvallis, Oregon 97331

Jeffrey C. Miller

Department of Entomology

Oregon State University

Corvallis, Oregon 97331

Eric B. Petersonc

Department of Botany and Plant Pathology

Oregon State University

Corvallis, Oregon 97331

and

Edward E. Starkey

U.S. Geological Survey

Forest and Rangeland Ecosystem Science Center

777 NW 9th Street, Suite 400

Corvallis, Oregon 97330
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

indicated that communities differed among stand types, and that communities in thinned stands

were not necessarily more similar to old-growth communities than were those in unthinned

stands. Variation in stand conditions appeared to enhance biodiversity, and hardwood trees and

shrubs were important for many species. These and other results form the basis for general

thinning guidelines, which are presented here, and will guide future research.

Key Words: biodiversity, bryophytes, community analysis, epiphytes, forest management,

functional groups, hardwoods, lichens, moths, neotropical migratory songbirds, Northwest Forest

Plan, old-growth forests, remnant trees, shrubs, thinning, variable-density thinning, vegetation.

2
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 3

Project Introduction

Overview

The Forest

Today the Douglas-fir/western hemlock forests of

western Oregon comprise both young-growth stands1

of small, relatively even-aged trees, and older, more

complex stands of large trees, including old-growth

stands (see Figure 1). Some of these forests are located

on federal lands within the area now managed

according to the Northwest Forest Plan (USDA and

USDI 1994; Figure 2). These federal lands support an

estimated 2,335,628 hectares of small conifer stands

(trees <53 centimeters in diameter) in Washington,

Oregon, and California. Medium/large conifer stands

(trees >53 centimeters in diameter2

) on these federal

lands include 1,623,550 hectares of single-storied

stands and 1,821,255 hectares of multistoried stands

(FEMAT 1993). Thus, about 40 percent of these federal

forests are relatively young-growth stands, many of

which have regenerated after timber harvest or forest

fire. Nonfederal Oregon forests include those forests

managed by state and private industry, most of which

have been logged and maintained in young age classes.

The Northwest Forest Plan

The Northwest Forest Plan incorporates seven landallocation categories for the ~10 million hectares of

federal forest lands located within the range of the

northern spotted owl3

 (Figure 2). These categories

include congressionally reserved areas,

administratively withdrawn areas, managed latesuccessional areas, late-successional reserves (LSRs;

e.g., Figure 3), riparian reserves, adaptive

management areas (AMAs), and matrix lands, i.e.,

areas not reserved (USDA and USDI 1994). The

allocation of large areas to reserves represents a major

change from the past, when most forest areas were not

protected or were managed with a major emphasis on

timber production. With the implementation of the

Northwest Forest Plan, new attention has been focused

on adaptive management (Figure 4), and on

maintaining and enhancing biodiversity, both in

reserves and on matrix lands from which timber will

be harvested.

1

 Terms related to forest ecology and forest management are set in boldface type at first mention and defined in the Glossary of

Forest Ecology and Management Terms. 2

 Ranges and cut-offs for size and age parameters vary, depending on the study objectives and data available, throughout this

report. Specific age and size parameters are provided to clarify study context and applicability, and to aid interpretation. 3

 One of three subspecies (Strix occidentalis caurina) of the spotted owl that ranges from British Columbia, Canada, into

northwestern California. The northern spotted owl is listed as a threatened species under the U.S. Endangered Species Act

by the U.S. Fish and Wildlife Service.

 A B C D

Figure 1. Vegetation in western Oregon from the coast to the crest of the Cascade mountains in 1988. (A) Young

stands (<80 years old) with >70 percent conifer cover. (B) Hardwood stands with >70 percent cover and mixed

vegetation. (C) Mature (>70 percent conifers between 80 and 200 years in age) and old-growth (>70 percent conifers

>200 years in age) vegetation. (D) Open areas with <70 percent green vegetation cover. Maps originator: Warren

Cohen, USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Lab, Corvallis, Oregon.
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

The Project

The Managing for Biodiversity in Young Forests

Project addresses the need to understand the potential

contribution of thinning as a management practice that

may be used to increase biodiversity in reserves, as well

as on matrix lands. This report presents the project

rationale and major results relating biodiversity to stand

characteristics for each of the organisms studied. It is

intended to supplement work highlighted in the project

video, Managing for Biodiversity in Young Forests

(Tappeiner et al. 2000), which depicts a day in the field

with researchers (see Appendix A4

) concerned with

managing young Douglas-fir forests for biodiversity. In

the video, Joe Lint, USDI Bureau of Land Management

Wildlife Biologist, teams up with Oregon State

4

4

 Researcher biographies are provided in Appendix A.

University Professor Pat Muir to visit researchers

comparing vegetation and fauna among Douglas-fir

stands, including unthinned and thinned young-growth,

and old-growth stands in western Oregon. The

researchers share their findings on trees, shrubs, and

herbaceous vegetation (John Tappeiner), epiphytic

lichens and bryophytes (Eric Peterson and Abbey

Rosso), moths (Jeff Miller), and birds (Joan Hagar).

Project results have important implications for forest

management, and researchers provide selected

recommendations for management actions that may

enhance biodiversity in young Douglas-fir forests.

Recommendations are intended primarily for agencies,

groups, and individuals who manage the Douglas-fir

forests of western Oregon. Results of complementary

research in the region are included, and data and

interpretations presented are based on the understanding

of young forests and their response to thinning at the

time of publication. The young-growth stands studied in

this project ranged from 50 to 120 years in age (average

79 years in age). The concepts and recommendations,

however, probably apply to stands ranging from

approximately 15 to 120 years in age.

Because the project is a retrospective analysis (i.e.,

stands were studied after they had been thinned, rather

than before and after), cause-and-effect relationships

between specific stand characteristics and the diversity

of the organisms chosen for study cannot be inferred

directly from the results. Even so, the project reveals

correlations between forest characteristics and

biodiversity—correlations that can be tested

experimentally in subsequent studies. In addition,

results from these and other studies (e.g., Carey et al.

Figure 2. The area of concern for the Northwest Forest Plan in Washington, Oregon,

and northern California, delineating federal

land ownership (light gray) and adaptive

management areas (dark gray). The

Northwest Forest Plan area is the habitat

range of the northern spotted owl. Adapted

from: Haynes and Perry 2000.

Figure 3. A late-successional reserve near Triangle

Lake, Oregon, northwest of Eugene, indicating young

forest over a large, contiguous expanse. Latesuccessional reserves are highly variable in age and

cover. Photograph by John Tappeiner.

Washington

Oregon

California
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 5

1999a; Colgan et al. 1999, 2000; Carey 2000; Haveri

and Carey 2000; Carey and Wilson 2001; Thysell and

Carey 2001; Carey et al. 2002) can be used now to help

design treatments that may enhance biological diversity

in reserves, as well as on matrix lands. Although

references are made to current concerns of land

Managing for Biodiversity

Biodiversity, or biological diversity, has been defined as the variety of life forms and processes, including

the species, communities, gene pools, and ecological functions of a given system—e.g., see Wilson (1988)

and Eldredge (1998) for overviews. As such, biodiversity is more than the sum of species that occupy a forest.

It includes the functional relationships among organisms as well. The literature on the planet’s loss of

biodiversity is filled with photographs, tables, and lists of organisms now threatened, endangered, or extinct,

as well as discussion of the profoundly serious nature of the issue.

Ecosystem management for biodiversity requires an understanding of the distribution and abundance of

species on the landscape and within stands, and an understanding of the responses of these species to

change—in both the short and the long term. Because environmental conditions affect forest stand structure

over time, essential habitat (provided by environmental conditions and stand structure, composition, and

processes) changes over time as well. Trophic interactions, i.e., the food web, involve important ecosystem

processes that interconnect organisms in a given habitat. Energy stored by plants is passed through the

ecosystem by a series of consumers. As a result, changes in vegetation may influence organisms at a variety of

trophic levels.

More information is needed about how forest practices and resulting changes in stand structure and

environmental conditions are likely to affect organisms, and how these effects move through food webs.

Understanding the functional relationships among organisms, as well as the organisms themselves, is essential

for those involved in managing forest ecosystems and maintaining biodiversity in young, managed forests.

MAKE ADJUSTMENTS

AND PLAN

MONITOR

ACT

EVALUATE

ADAPTIVE MANAGEMENT PROCESS

Figure 4. Forest managers implementing the Northwest Forest Plan

focus efforts on an adaptive management process through which

management activities are monitored, evaluated, considered along

with findings of ongoing research, and adjusted to increase the

degree to which they meet management objectives over time.

managers about implementation of the Northwest Forest

Plan, research findings are relevant to the practice of all

agencies, groups, and individuals concerned with

enhancing biodiversity in young forests typical of those

found in western Oregon.
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Reserves, AMAs, and Matrix Lands

A variety of land areas, in large part, are reserved from timber management. These areas include

congressionally reserved areas (e.g., national parks and wilderness areas) and administratively withdrawn

areas (e.g., identified recreation and visual areas), as well as the LSRs and riparian reserves set aside under

the Northwest Forest Plan. Late-successional reserves are managed to protect or foster development of latesuccessional forest conditions and to provide habitat for species that depend on late-successional habitat.

Riparian reserves are riparian areas located outside of LSRs and have similar management objectives, as well

as broad aquatic-conservation strategy objectives.

Stand management in LSRs and riparian reserves is intended to encourage late-successional characteristics

and riparian values, respectively, rather than timber production. Some stand-management practices in these

reserves do produce wood, but this production is not the motivation behind their implementation. For

example, thinnings and other silvicultural practices are encouraged, both to accelerate the development of

young stands (generally <80 years old) into stands with late-successional characteristics and to reduce the risk

of severe impacts from large-scale disturbances (USDA and USDI 1994).

Adaptive management areas are areas in which adaptive management is mandated (see Figure 4). At

present, ten AMAs have been set aside for developing and testing management approaches that help integrate

ecological and economic health objectives.

Matrix lands are areas that are not reserved, i.e., they are located outside of reserves. The objectives for

matrix lands remain largely the same as they were prior to the development of the Northwest Forest Plan,

with some added objectives, such as protection of sensitive plants, animals, and fungi (i.e., survey and

manage species) and the important habitat features (e.g., remnant green trees, coarse woody debris, and

snags). Most scheduled timber harvest (other than harvest in adaptive management areas) takes place on

matrix lands.

5

 See “Douglas-Fir Forests in Western Oregon” in the Project Introduction section of this report.

Forest Stand Development

John Tappeiner

According to generally accepted theory, forest stands

tend to develop in a sequence from small seedlings and

saplings to dense, closed-canopy stands with narrow

age ranges, and then to complex, multistoried, oldgrowth stands (see Oliver and Larson 1996). At present,

many young forests in western Oregon comprise trees

with a narrow range of ages (Figure 5a), in keeping

with the first part of this sequence.5

 Increasing

evidence, however, suggests that existing old-growth

forests started under conditions quite different than

those found in the dense, closed-canopy stands from

which today’s young forests generally develop (e.g.,

Tappeiner et al. 1997; Poage 2001; Figure 6).

Based on the 40 stands included in these studies,

old-growth stands appear to have comprised trees of a

range of ages and sizes. Thus, disturbance and tree

establishment may have been ongoing and common

processes on sites similar to those on which studies

described in this report were conducted. The old-growth

stands sampled by Tappeiner et al. (1997) and Poage

6

A

B

Figure 5. Representation of forest stand development.

Diagrams depict: (A) trees in unthinned young-growth

stands today, with slow growth rates and a narrow

range of age, and (B) recent findings on existing oldgrowth forests, which indicate that trees developed

with fast growth rates during the early years and a

wide range of age.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

(2001) at sites in the Oregon Coast Range contained

trees that grew under low stocking densities and

sustained high growth rates during their first 100 years.

The growth and age of large trees in these old-growth

forests, measured by counting rings on stumps in stands

that have been clearcut (Tappeiner et al. 1997; Poage

2001), indicate that the density of large trees (>75

centimeters) in these former old-growth stands was

variable and low—often <50 trees per hectare. Tree-ring

analyses also indicate rapid diameter growth rates

during the first 50–100 years of growth in these large

trees. In addition, tree size and/or growth rate at age 50

years explained >70 percent of the variation in tree size

at age 200 years (Poage 2001). Thus, these old trees

apparently grew quickly at low densities during early

7

Figure 6. A young forest, between 30 and 50 years in

age, started following timber harvest in the Oregon

Coast Range near Harlan. Existing old-growth forests

may have started under conditions that differ from the

dense, closed-canopy conditions of stands from which

young forests generally develop today. Photograph by

John Tappeiner.

Figure 7. Stump of an old tree and disk from the

stump of a young tree in the Oregon Coast Range just

west of Corvallis. Marks are set at intervals of 10

years, and indicate rapid growth of the old tree and

slower growth of the young tree during the early

years. Photograph by John Tappeiner.

stages of their lives, and maintained diameter growth as

they aged (Figure 7). Spies and Franklin (1991) also

have reported low tree densities for old-growth forests

in western Oregon and Washington. By comparison,

current densities of canopy trees in the Oregon Coast

Range are much higher in unthinned young-growth

stands (Bailey and Tappeiner 1998). In the thinned

young-growth stands studied in the Managing for

Biodiversity in Young Forests Project, tree densities

generally were lower than in unthinned young-growth

stands, but were quite variable (between 59 and 289

trees per hectare), depending on the thinning

prescription. The densities in these thinned younggrowth stands generally were much higher than

densities found in old-growth stands (see Figure 5b).

Comparisons of the diameter growth rates at 50

years of age in trees in unthinned young-growth stands

planted for timber production to those of old trees at the

same age indicate that the diameter growth of the 50-

year-old trees is consistently less than that of the old

trees. However, researchers have found that the growth

of young trees thinned to about 125 trees per hectare is

similar to that of old trees (Curtis and Marshall 1986).

These young-growth stands are productive and have

accumulated biomass rapidly (Curtis and Marshall

1986). Therefore, the relatively slower diameter growth

of trees in unthinned young-growth stands (Figure 8) is

Figure 8. Unthinned young-growth stand,

approximately 20 years in age. Note the high

density of trees with little development of the

understory. Photograph by John Tappeiner.
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

likely a result of high tree density (commonly >250

trees per hectare) and competition among trees, rather

than a change in site productivity. Density reduction

(thinning) will be necessary in young-growth stands if

these stands are to develop trees with the characteristics

of large trees in old-growth stands quickly.

Another consideration is that trees in current oldgrowth stands appear to have become established over a

period of many years, and often vary in age by a range

of several hundred years (Figure 5b). For example, in a

single plot, large trees can range from 100 to >300 years

in age (Tappeiner et al. 1997; Poage 2001). In contrast,

the range of ages in young-growth Douglas-fir stands is

often quite small, e.g., 5–10 years (Figure 5a). Therefore, the old-growth stands appear to have developed by

a gradual establishment of trees over time, probably in

conjunction with intermittent disturbances.

These results, and others, support the conclusion that

regeneration of these old-growth stands occurred over

a prolonged period, and that trees grew at low densities

with little self-thinning. In contrast, after timber

harvest, young-growth stands often develop with high

densities of trees of similar age and considerable selfthinning. Young-growth stands today primarily contain

trees that were established at about the same time, and

Figure 9. (A) A thinned site typical of those surveyed

during studies that were part of the Managing for

Biodiversity in Young Forests Project and (B) old growth

in the Oregon Coast Range. The young-growth stand

was thinned fairly heavily and has developed an

understory containing shrubs and conifers. The oldgrowth stand supports relatively few large trees spaced

widely, and an intermediate structure in the understory.

Thinning may help accelerate the development of oldgrowth characteristics in dense young stands. Photographs by John Tappeiner (A) and John Bailey (B).

8

A B thus are developing as a single cohort of even-sized,

competing trees (Tappeiner et al. 1997). The rationale

for thinning is based, in part, on the contrast between

diameter growth rates that trees in old-growth forests

achieved when they were young and growth rates that

trees in today’s young-growth stands achieve. Thinning

may help accelerate the development of old-growth

characteristics in dense young-growth stands (Tappeiner

et al. 1997; Poage 2001; Figure 9). Old-growth

characteristics include not only characteristics of the

trees themselves but also functional and compositional

features of the forest ecosystem.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 9

Douglas-Fir Forests in Western Oregon

Wayne E. Elliott

Most of the federal lands in western Oregon are

managed by the USDI Bureau of Land Management

(BLM) and the USDA Forest Service. The history of the

federal lands managed by BLM is provided here to

illustrate the nature of these forests, their age-class

distribution, and the basic philosophy that has guided

their management.

History of Forest Management

The USDI Bureau of Land Management (BLM)

manages a diverse array of natural resources on over

1 million hectares in western Oregon. These lands

primarily comprise an extensive checkerboard

ownership pattern, as a result of the history of land

grants and revestments involving the federal

government and private partners, primarily railroad

companies. The lands include nearly 850,000 hectares

of revested Oregon and California Railroad lands (O &

C lands), nearly 162,000 hectares of public lands, and

about 30,000 hectares of Coos Bay Wagon Road lands.

Forested lands make up approximately 890,000

hectares (~90 percent) of the BLM-managed lands in

western Oregon. Extensive areas of these forest lands

are covered by young, relatively even-aged forest

stands (<40 years in age), with low structural and

compositional diversity (see Figure 10). These younggrowth stands are the result of management with a

major emphasis on wood production according to the

principles of sustained-yield management, traditionally

defined as “management intended to sustain the longterm production of wood volume.” This philosophy

guided BLM-management activities for many decades

prior to current changes related to implementation of

the Northwest Forest Plan.

0

2 0

4 0

6 0

8 0

100

120

140

160

0

1 02 03 04 05 06 07 08 09 0

100110120130140150160170180190

200+

Age Class (years)

Figure 10. Age-class distribution of all forest lands

managed by BLM in western Oregon. Source: USDI

Bureau of Land Management.

The O & C lands constituted a unique public trust in

the Pacific Northwest in the early 1900s. The lands

were transferred to railroad-company ownership as a

subsidy to help finance a critical north-south railway

link from Portland, Oregon, to northern California. The

subsequent sale of these lands was intended to stimulate

economic development and community stability in

struggling counties in western Oregon. Although the

railroad was completed, the construction company

declared financial bankruptcy and the federal

government reclaimed remaining O & C lands in 1917.

In 1937, Congress passed the O & C Act (50 Stat. 875,

chapter 876, 43 USC 1181f), which directed that these

lands be placed within the Department of the Interior

and be managed:

• “for permanent forest production in conformity

with the principles of sustained-yield

management,”

• to “fix allowable cuts of timber, protect watersheds,

regulate stream flow, contribute to local economic

stability and provide recreational facilities,” and

• to “distribute timber receipts to O & C counties and

to the federal treasury for O & C land

management.”

In July 1946, Congress approved President Truman’s

plan to merge the General Land Office and the U.S.

Grazing Service to form BLM. The challenge for BLM

was to manage these lands and meet the multiple

provisions of the 1937 O & C Act. Foresters regarded

these forest lands to be among the most productive

forests in North America. Douglas-fir was the dominant

conifer species, and provided wood material of great

strength and quality to a nation eager to construct

houses and move beyond the Depression years. In

general, managers regarded short-rotation, even-aged

forest management as the appropriate management

direction for these lands to meet the congressional

directive, as well the as legislative, funding, and

other directives.

During the postwar era of the 1950s, timber

management intensified on BLM lands in western

Oregon. Emerging silvicultural practices in North

America included clearcutting, removing logs and

snags, slash burning, thinning, and planting singlespecies stands on cutover areas (FEMAT 1993). These

practices were based on the assumption that forests

managed in this way could be cut and regrown at

relatively short intervals (e.g., 40–80 years) without

negatively affecting long-term site productivity or other

resources, such as water quality and soils.

Harvests continued to be guided by these principles

through the 1960s and 1970s, and averaged slightly less

than 5.66 million cubic meters (1 billion board feet) per

year on BLM lands in western Oregon. Further, harvest
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

records indicate annual averages on BLM lands of 5.02

and 5.50 million cubic meters for the respective periods

1970–1979 and 1980–1989 (886 and 971 million board

feet, respectively; Oregon Department of Forestry

1999). However, these annual harvests continued to be

less than the calculated sustained-yield harvest of 6.80

million cubic meters (1.2 billion board feet) for these

lands. Timber harvest was reduced during the 1990s

with the listing of the northern spotted owl as

threatened under the U.S. Endangered Species Act in

June 1990. Additional listings, e.g., the marbled

murrelet and various stocks of anadromous fish,

occurred soon afterwards and resulted in further

reductions in timber harvest.

Reforestation, necessary for timber production and

watershed protection, included site preparation, usually

by broadcast burning or burning slash piles; planting

with nursery-grown seedlings from local seed sources

or genetically improved stock; and brush control, if

needed, to reduce competition around conifer seedlings.

Initial planting densities varied, as did the frequency

and intensity of precommercial or commercial

thinning. These practices focused on timber

management and left a legacy of dense, rapidly

growing, young Douglas-fir stands.

Current Age-Class Distribution of Young-Growth Stands

Past harvest and reforestation activities have resulted

in the even-aged stands characteristic of young growth

in the region today. Current age-class distribution data

for all land-use allocations (USDI Bureau of Land

Management 1992) show that young-growth stands

occupy extensive areas of lands managed by BLM in

western Oregon. Approximately 35 percent of the

agency’s 890,000 hectares of forest lands in western

Oregon have an average tree age of <40 years (Figure

10). Approximately 14 percent of these lands support

forests in the 40-, 50-, and 60-year age classes. Current

stand age-class distributions reflect past harvest rates

and disturbance events such as fire. Harvest activity in

the 1940s and 1950s is reflected in the 50- and 40-year

age-class distributions, respectively. Similarly,

increased harvest activity in the 1960s and 1970s is

reflected in the larger areas in the 30- and 20-year age

classes. Harvest rates in the 1980s are reflected in the

10-year age class, which occupies over 100,000

hectares of BLM lands in western Oregon (USDI

Bureau of Land Management 1992).

These forest stands are young, densely stocked, and

relatively uniform in age. Variation in tree age is usually

<10 years, because these stands were planted with

nursery stock and had some natural regeneration

within 10 years of planting. Structural and biological

diversity often are low, and areas that have been

clearcut and artificially regenerated show little age

variation. Before the Northwest Forest Plan, these

stands would have been managed to produce high

yields of wood.

Changing Forest-Management Objectives

Forest management changed significantly on BLM

lands in the 1990s with the completion of the Forest

Ecosystem Management Assessment Team report

(FEMAT 1993) and the Northwest Forest Plan (USDA

and USDI 1994). Whereas 90 percent of the land base

had been dedicated to a “non declining even flow of

timber,” now 65 percent of the BLM land base within

the area covered by the Northwest Forest Plan is

designated as late-successional and riparian reserves.

Although the Northwest Forest Plan significantly

changed allocations and objectives for forest

management, it did not, and could not, rapidly change

the condition of the forests, which have been created

over decades.

These young, unnaturally dense, Douglas-fir forest

stands on BLM lands in western Oregon today provide

abundant opportunities for thinning to help develop

more biologically diverse and structurally complex

forests. Stands <40 years old and those in the 40–60-

year age class are located primarily in reserves (Figure

11), where treatments, including thinning, are being

focused on enhancing biodiversity and accelerating the

development of old-growth characteristics. On matrix

lands, the opportunity for commercial wood production

exists as a result of needed treatments. As the research

studies that are part of the Managing for Biodiversity in

Young Forests Project indicate, thinning on these lands

may contribute to stand vigor and increase vertical and

horizontal vegetative structure for a variety of plant and

wildlife species.

10

Age Class (years)

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

0 10 20 30 40 50 60 70

Matrix lands

LSRs and riparian reserves

Other reserves

Figure 11. Age-class distribution of forest stands <80

years in age on BLM lands in western Oregon. Source:

USDI Bureau of Land Management.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

Project Objectives

The Managing for Biodiversity in Young Forests

Project is a retrospective analysis, initiated with studies

by John Bailey and John Tappeiner, of forest stands

typical of those being managed on federal lands in

western Oregon. The main question addressed by the

project is whether or not biodiversity tends to increase

in areas that have been thinned, an observation often

made by people who spend time in forests. Such

observations have encouraged managers to consider

thinning as a management tool that supports the

development of old-growth characteristics, including

the increased diversity of organisms often considered to

be old-growth-associated, in young forests.

Among the specific questions addressed by the

project with regard to thinning are the following:

1. Do communities of selected organisms differ

among unthinned young-growth, thinned younggrowth, and old-growth stands?

2. If communities do differ among stand types, is

there evidence that thinning may accelerate the

development of community similarity between

young-growth and old-growth stands?

3. Do the diversity and abundance of selected forest

organisms appear to be related to specific stand

features, such as shrubs, hardwood trees, remnant

old trees, and snags?

4. Are there commonalties across the various

organisms studied in terms of stand features that

seem important for supporting a relatively high

diversity or abundance? In other words, can key

structural or compositional features be identified,

and will enhancement or protection of these

features during management of young-growth

stands foster maintenance or development of high

native biodiversity?

In addressing these questions, the studies share the

following overall objectives6

:

• To contribute to existing understanding of young

forests and their management.

• To contribute to guiding the direction of work that

can be done to enhance biodiversity through

management of young forests in western Oregon.

Project results may provide a basis for forestecosystem management in the Pacific Northwest

from which future management strategies can be

refined (i.e., through ongoing adaptive

management; see Figure 4).

6

 Additional objectives of individual studies that are part of this project are provided in the Study Objectives, Results, and

Recommendations for Management section of this report.

• To inform those who manage forest lands in

western Oregon of the potential effects of

management practices.

• To increase understanding of factors influencing

native biodiversity in forests of western Oregon,

and how these factors might be manipulated to

enhance forest biodiversity.

11
12 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Materials and Methods7

Project Study Area

Description of Study Area

The Managing for Biodiversity in Young Forests

Project comprises studies conducted primarily in

young- and old-growth stands typical of the Douglas-fir

forests in the Coast Range and Cascade mountains of

western Oregon. Stands chosen for research (Table 1;

Figure 12) included 32 pairs of unthinned and thinned

young-growth stands and 20 old-growth stands

originally inventoried by Bailey (1997). The old-growth

stands usually were located within 10 kilometers of,

and were similar in site conditions to, 20 of the 32

paired unthinned-thinned stands. This group of stands,

i.e., the unthinned-thinned pair of young-growth stands

and the associated old-growth stand, is referred to as a

“stand triad.” Additional stands were included for

several of the studies (see Table 2; Figure 13). Most of

the stands inventoried were located on federal lands

managed by BLM.

The study area in which stands were located

included the region from just south of the Columbia

River in the Cascade mountains, to west of Tillamook in

the Coast Range, and west of Medford in southwestern

Oregon (Figure 12). Stand elevations ranged from 250

to 800 meters, and precipitation, primarily in the form

of rain, was 100–300 centimeters annually (Bailey

1997). Most stands were in the Western Hemlock Zone

(Franklin and Dyrness 1988).8

 The shrub layers largely

comprised common understory species such as salal,

bracken fern, vine maple, Oregon-grape, and sword fern

(see Appendixes B–C9). Each stand was large enough to

allow for sampling of 10 hectares of interior habitat (see

Bailey 1997). Researchers sampled not only various

combinations of the same stands but also generally

within the same portions of each of the selected stands

as were sampled by Bailey (1997).

Young-Growth Stands

The criteria met by the 32 pairs of unthinned and

thinned young-growth stands included the following:

• Stands were ≥50 years in age at the beginning of

the study.

• Thinned stands were similar to the unthinned

stands with which they were paired in terms of

7

 Additional detail can be found in Hagar et al. (1996), Bailey (1997), Peterson and McCune (2000a–b, 2001), Peterson et al.

(2000), and Rosso (2000). 8

 Several of the southern sites were located within or near the transition into the Douglas-fir Zone (Franklin and Dyrness 1988). 9

 Common and scientific names of vegetation referred to in the text are provided in Appendix B. Selected taxonomic resources

are listed in Appendix C.

Figure 12. Study area in western Oregon and

approximate locations of study sites surveyed during

the Managing for Biodiversity in Young Forests Project.

slope, aspect, elevation, and potential natural

vegetation type.

• Documentation of the year and intensity of thinning

implemented was available.

• No additional management treatments other than

thinning had been conducted in any of the younggrowth stands.

An even-sized cohort of Douglas-fir dominated the

overstory of the young-growth stands. Few residual

large trees or snags from previous stands remained in

the stands. Prior to thinning, each young-growth stand

occupied the area that would become adjoining

unthinned and thinned stands, with an arbitrary

separating line between them. Thinning was completed
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 13

through BLM timber sales, generally 10–20 years

before the project was initiated (Table 1).

Stands were thinned only once, and thinning ranged

from heavy to light. Typically, approximately 25–30

percent of the stand volume was removed during

thinning operations, and removal ranged from 8 to 60

percent across all stands. Relatively large dominant and

codominant trees were left in the stands, and relatively

small trees of commercial size were removed from the

main canopy to favor the development of conifers with

large crowns and stems (i.e., “thinning from below”).

In general, conifers <15 centimeters in diameter at

breast height (DBH) and hardwoods were left in the

stands. No other treatments were applied to the thinned

Table 1. Description of unthinned and thinned young-growth stands and old-growth stands surveyed during the

Managing for Biodiversity in Young Forests Project (modified from Bailey 1997). Approximate locations are

indicated by site number in Figure 12.

S n ite L s ocatio Organism a Y ) oung-growth stand description Density (trees per hectare

V E MB e Stand ag

(years)

Site

indexb

Year

thinned

% volume

removed

Young-growth

stands

Old-growth

stands

U d nthinned Thinne

1 n Bald Mountai * 7 0 0 1 6 2 1 3 97 3 9 2 6 4 1 - 4 -

2 k Bear Cree * * 1 4 00 1 2 3 1 7 97 2 3 1 8 3 1 1 2 8

3 k Sand Cree ** * 7 8 0 1 1 2 1 2 97 3 5 4 9 1 2 4 8 5

4 t a Beaver Fla * * ** 5 0 0 1 4 3 1 1 97 5 3 3 1 2 1 7 5 4

4bc Marys Peak paired

young-growth * 5 - 0 - 0 1 0 98 3 0 5 0 3 1 - 2 -

5 d Highpass Roa * 9 4 0 1 1 1 1 0 97 2 0 1 3 6 1 9 3 4

6 e Bummer Ridg * 9 8 5 9 6 1 5 97 2 8 1 1 7 1 - 1 -

7 e Gnom * * ** 6 0 0 1 3 2 1 3 98 4 4 4 6 9 1 4 4 6

8 d D-Line Roa ** * 6 1 0 1 2 2 1 2 97 1 8 3 3 8 1 7 8 7

9 k Clay Cree * 7 9 0 1 0 1 1 8 98 4 2 2 0 5 1 - 8 -

1 k 0 North Ward Cree * * ** 5 0 0 1 5 3 1 0 98 5 7 2 3 3 1 4 5 5

1 t 1 Elliott State Fores * * 1 1 00 1 3 3 1 4 97 5 0 2 1 3 1 4 2 10

1 k 2 Little Wolf Cree * * 6 2 0 1 0 0 1 5 98 5 1 2 3 9 1 2 4 5

1 6 3 Blue Ridge 2 * * 5 7 0 1 6 2 1 0 97 1 7 4 0 4 2 2 3 6

1 5 4 Blue Ridge 3 * 5 7 0 1 2 2 1 8 98 2 7 4 3 4 1 - 6 -

1 k 5 Burnt Cree * * 8 7 0 1 5 1 1 3 97 3 3 1 7 5 7 26

1 p 6 Panther Ga * * 1 8 20 7 1 1 0 98 2 6 1 9 5 9 98

1 k 7 Days Cree * 9 7 0 1 7 1 1 0 97 4 2 2 9 4 6 --

1 e 8 Windy Ridg * * 8 5 0 1 7 1 1 0 97 4 8 3 5 8 1 9 7 6

1 r 9 Little Rive * 1 6 10 9 8 1 0 97 3 2 2 9 7 1 - 0 -

2 k 0 Honey Cree *** 1 8 00 9 1 1 1 97 2 8 1 8 9 1 4 2 5

2 r 1 Big Rive * 8 0 0 1 7 3 1 5 97 1 9 2 5 5 1 - 7 -

2 d 2 Wildwoo * 6 1 5 1 1 2 1 2 98 2 1 5 2 4 2 - 5 -

2 1 3 Perkins Creek # * * 6 4 0 1 1 3 1 6 98 3 9 2 5 5 1 6 9 10

2 2 4 Perkins Creek # * 6 5 0 1 1 1 1 0 98 3 0 3 5 6 2 - 2 -

2 t 5 Eagle’ s Res * * 9 0 0 9 4 1 0 97 5 6 1 7 4 7 69

2 e 6 Marten Ridg * * 7 7 0 1 1 2 1 0 98 5 2 2 9 7 5 96

2 t 7 Keel Fla * * 6 1 0 1 1 4 1 5 97 2 9 2 8 8 1 2 4 4

2 k 8 Fawn Cree * 1 0 20 1 2 1 1 81 97 1 4 1 8 --

2 k 9 Rooster Roc * * 1 4 10 1 1 1 1 2 97 2 3 1 3 8 1 9 6 6

3 k 0 Horse Cree * 1 2 10 8 1 1 0 97 2 8 1 3 8 1 - 5 -

3 k 1 Meyer Cree * 1 6 20 1 0 0 1 3 97 2 9 2 6 6 1 - 2 -

3 k 2 Gordon Cree * * 6 8 0 1 5 1 1 0 98 6 1 2 1 9 1 4 2 8 a V = vegetation, E = epiphytes, M = moths, and B = birds. b King (1966), base age 50. c Unthinned-thinned pair of young-growth stands on Marys Peak, Siuslaw National Forest, sampled in place of Beaver

Flat young-growth stands after that site was harvested.
14 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

stands. Overstory density of trees >20 centimeters DBH

ranged from 111 to 541 trees per hectare in unthinned

stands, and from 59 to 289 trees per hectare in thinned

stands during the time that the studies were conducted.

Old-Growth Stands

Old-growth stands located near 20 of the unthinnedthinned pairs of young-growth stands supported trees

>200 years in age, and exhibited characteristics

described by Franklin and Spies (1991)—e.g., the

overstory trees were large (>100 centimeters DBH) and

the stands were multilayered with relatively low tree

densities. Old-growth stands had 47–106 trees >20

centimeters DBH per hectare and a highly variable

understory of seedlings, saplings, and shrubs. Little

evidence of human disturbance was present in the oldgrowth stands.

Project Study Stands

Data on over- and understory trees, shrubs, and

herbaceous vegetation were collected on 32 pairs of

unthinned and thinned young-growth stands, and 20

old-growth stands, i.e., all except site 4b, Table 1 (see

also Figure 12; Bailey 1997; Bailey and Tappeiner

1998; Bailey et al. 1998). Research on other organisms

was conducted on various combinations of these

particular stands, as follows (Tables 1–2; Figure 12):

• Epiphytes—sites 2–4a, 7–8, 10–11, 13, 15, 18, 20,

23, 25–27, 29, and 32.

• Moths—sites 4a, 7, 10, 16, and 20.

• Birds—sites 3–4a/b, 7–8, 10, and 12.

Additional project study stands included (1) 17

landscape-level hotspots, one associated with each of

the 17 stand triads inventoried for epiphytes, (2) 4

clearcuts and a meadow (site 16), one associated with

each of the 5 stand triads sampled for moths, and

(3) an unthinned-thinned pair of young-growth stands

(site 4b) on Marys Peak, Siuslaw National Forest,

associated with one of the 6 stand triads (site 4a)

sampled for birds.

Researchers studying epiphytes worked at 17 of the

stand triads (Tables 1–2; Figure 12) and at associated

landscape-level hotspots. The hotspots were areas that

seemed likely to support an unusually high abundance

or diversity of epiphytes, or epiphytes that generally are

uncommon in relatively homogeneous, coniferdominated forests. Much of the within-stand diversity

and abundance of epiphytes in managed young

coniferous forests often is associated with unusual stand

features, such as hardwoods or remnant trees (Neitlich

and McCune 1997). Hotspots were included in these

studies because relatively less is known about the

importance of unusual large-scale (landscape-level)

features for epiphytes than about the importance of

within-stand features. Hotspots were located through

examinations of aerial photographs of the area near

each set of young- and old-growth stands, and

subsequent observations on the ground. Aerial

photographs helped in identifying hotspots by structure

(e.g., areas with hardwood-dominated gaps) and

topography (e.g., riparian areas and those with rocky

outcrops). On the ground, researchers looked for

species normally associated with rich communities,

primarily nitrogen-fixing species. Hotspots were

chosen near (usually within 4 kilometers of) each

unthinned-thinned pair of young-growth stands

sampled. Hotspots sampled in the epiphyte studies

included 11 riparian areas, 3 hardwood gaps (relatively

open forest areas occupied by hardwood trees or

shrubs), 2 rocky outcrops, and an opening that had been

created by a road.

The moth study was focused on five of the stand

triads (Tables 1–2; Figure 12). Four clearcuts and a

meadow (site 16) were included in the study to increase

the degree to which samples represented the range of

forest conditions found in the study area. The clearcuts

were located near the remaining stand triads sampled,

and were harvested up to 15 years prior to the initiation

of the project. The clearcuts and meadow had site

conditions and associated vegetation that differed

Table 2. Summary of forest stands surveyed during the Managing for Biodiversity in Young Forests Project.

P ) roject study organisms Major forest stands (number a Additional stands

Stand triadsb Paired younggrowth stands

T 0 rees, shrubs, and herbaceous vegetation 2 21 --

E 7 piphytes 1 -- s 17 hotspot

M 5- oths - w 4 clearcuts, 1 meado

B 6- irds - h 1 paired young-growt c

a Sites studied by Bailey (1997). b Paired unthinned and thinned young-growth stands, with associated old-growth stand. c Pair of unthinned and thinned young-growth stands located on Marys Peak, Siuslaw National Forest.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 15

considerably from those found in young- and oldgrowth stands, and seemed likely to support different

moth communities.

Birds were surveyed in six of the stand triads (Tables

1–2; Figure 12). An additional pair of young-growth

stands on Marys Peak (site 4b), Siuslaw National

Forest, was included for this portion of the project,

because one pair of young-growth stands (site 4a) was

harvested before bird sampling was completed. This

additional pair of unthinned and thinned young-growth

stands was located near the old-growth stand sampled

with the harvested pair of stands.

Figure 13. Organisms in a range of habitats were sampled during the Managing for Biodiversity in Young Forests

Project. Stand types surveyed for vegetation, epiphytic lichens and bryophytes, moths, and birds included: (A)

unthinned, (B) thinned, and (C) old-growth stands. In addition, (D) clearcut stands were surveyed for moths, and

hotspots were surveyed for epiphytic lichens and bryophytes. (E) Riparian areas and (F) hardwood gaps were

among the types of hotspots sampled. (See also Figure 12 and Table 1.) Photographs by Ruth Jacobs (A–B), Eric

Peterson (C, E), Jeff Miller (D), and Bruce McCune (F).

A. Gnome (site 7) B. Gnome (site 7) C. D-Line Road (site 8) D. Honey Creek (site 20)

E. D-Line Road (site 8) F. Typical site
16 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Study Organisms

Organisms chosen for study as part of the Managing for

Biodiversity in Young Forests Project included trees,

shrubs, and herbaceous vegetation; lichens and

bryophytes growing on trees and shrubs (epiphytes);

moths; and birds. These organisms have complex

interdependencies that are only partially understood

(Figure 14), as described in this section. Selection was

limited to these particular organisms primarily by

logistics and available funding.

Trees, Shrubs, and Herbaceous Vegetation

Forests of western Oregon are prominent features of

the landscape. Trees, shrubs, and herbaceous vegetation

in these forests provide shelter, substrate, and food for

forest organisms. In addition, they provide organic

matter to soils, play a major role in nutrient cycling,

protect watersheds from erosion, and enhance the

aesthetics of forest ecosystems. Because forest

composition and structure change with age,

communities of forest organisms that depend on

vegetation often change as well. Forest managers need

information on such changes in vegetation and

associated species, and on how these changes can be

influenced by management activities, in their efforts to

foster biodiversity in forests. Effects of various forestmanagement strategies on vegetation in the Pacific

Northwest have received increased attention recently

through both retrospective (e.g., Thysell and Carey

2000; Traut and Muir 2000) and experimental (e.g.,

Halpern et al. 1999; Thysell and Carey 2001)

approaches. Results from such studies, and the findings

of studies reported here, will inform managers’

attempts to enhance the diversity of vegetation and

associated species in forests typical of those located in

western Oregon.

Figure 14. Some of the interactions that occur among groups of organisms studied during the

Managing for Biodiversity in Young Forests Project. Interactions studied as part of the project

are indicated by boldface type.

C

A

A, B A

C

D

B

E

B, F

G, H

C

BIRDS

TREES, SHRUBS, AND

HERBACEOUS VEGETATION

MOTHS AND OTHER

ARTHROPODS

EPIPHYTIC LICHENS

AND BRYOPHYTES

INTERACTIONS

A—provide food for

B—provide habitat/substrate for

C—disperse propagules for

D—provide nesting material for

E—provide fixed nitrogen for

F—source of camouflage for

G—are pollinators for

H—are decomposers of
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 17

Epiphytic Lichens and Bryophytes

Lichens (Figure 15) and bryophytes (mosses,

liverworts, and hornworts) are prominent epiphytes in

western Oregon forests, and are important components

of these ecosystems. They serve as nitrogen-fixers (e.g.,

Lobaria oregana), providing important inputs of plantavailable nitrogen to ecosystems; as hydrological

buffers, by absorbing, storing, and releasing water (e.g.,

moss mats); as part of food webs (e.g., in the diet of

arthropods, flying squirrels, deer, and elk); as nesting

material for marbled murrelets, flying squirrels, and

other birds and mammals; and as habitat for insects and

other arthropods. In addition, epiphytic bryophyte mats

are harvested as a secondary forest product (see Peck

and Muir 2001). In many Pacific Northwest forests, the

biomass of lichens and bryophytes on trees exceeds

several tons (dry mass) per hectare (McCune 1993).

Figure 15. Lichens generally are grouped into three

forms: (A) foliose, (B) crustose, and (C) fruticose. The

foliose and fruticose lichens together are known as

macrolichens. Photographs by Bruce McCune.

A. Lobaria oregana

B. Thelotrema lepadinum C. Bryoria pseudofuscescens

Epiphytic Lichens and Bryophytes

Epiphytes

Lichens and bryophytes are common epiphytes in forests of western Oregon. Epiphytes are nonparasitic

organisms that grow on plants. They derive most of their moisture and nutrients from the atmosphere.

Lichens

Lichens are symbiotic associations between a fungus and a photosynthetic partner (green algae,

cyanobacteria, or both). Lichens generally are grouped into three forms on the basis of their overall habit

and morphology. These forms are:

• foliose: leaflike, flat and only partially attached to the substrate.

• crustose: crustlike, tightly attached to the substrate along the lichen’s lower surface.

• fruticose: shrublike, standing out from the surface of the substrate.

The foliose and fruticose lichens together are known as macrolichens, and these were the focus of the

studies included in this project.

Macrolichens often are divided into three functional groups, based on their role in the ecosystem:

• forage lichens: generally fruticose lichens, also known as “alectorioids” (including Alectoria spp. and

Bryoria spp.), used for forage by a variety of mammals.

• matrix lichens: the remainder of the macrolichens, which typically are dominant lichen species in

young forests. These macrolichens sometimes are known as “green algal foliose lichens” to distinguish

them from nitrogen-fixing and forage lichens.

• cyanolichens: lichens containing cyanobacteria as the primary photosynthetic partner, which enables

them to fix atmospheric nitrogen. These lichens also are known as “nitrogen-fixing macrolichens.”

Bryophytes

Bryophytes include mosses, liverworts, and hornworts. For purposes of this project, bryophytes were

divided into:

• mats: spreading along the surface.

• tufts: standing out in a spherical to hemispherical arrangement from a main point of attachment.
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Communities of lichens and bryophytes develop

slowly. Because of this, many of these species are

considered to be associated with old-growth forests

(Lesica et al. 1991; McCune 1993; Neitlich 1993). Oldgrowth forests generally have a higher diversity and

abundance of epiphytes than do stands <150 years

old, and the epiphyte communities present in oldgrowth forests differ from those in young forests

(Lesica et al. 1991; McCune 1993; Neitlich 1993).

Changes occur in abiotic conditions as forest stand

structure changes over time (e.g., light and moisture in

the mid- and lower canopy generally increases), and

these changes appear to facilitate epiphyte community

development. Nonetheless, the factors that limit

epiphyte distribution are poorly understood. For most of

these species, it is not known whether they require

specific structural and biological features characteristic

of relatively old forests, or simply are slow to

disperse, establish, or grow—thus slowing the rate at

which they recolonize an area after tree harvest and

thereby resulting in an association with relatively old

forests (Peck and McCune 1997; Sillett et al. 2000).

Because of their importance in forest ecosystems,

and the association of many species with old-growth

forests, epiphytic lichens and bryophytes are

increasingly being considered in the practice of forestecosystem management (FEMAT 1993; USDA and

USDI 1994). More than 65 species of lichens and

bryophytes are listed as potentially sensitive to

management practices, and specifications about

epiphyte survey and management are prescribed in the

Record of Decision and Standards and Guidelines

(USDA and USDI 2001). More than 20 of these species

occur only in the Pacific Northwest.

Moths

Moths function in the dynamics of forest ecosystems

during both their caterpillar (immature) and flying

Figure 16. Although numerous moths are generalists

and can feed on a range of vegetation species, some

are specialists and can survive only if the particular

food for which they are specialized is available. Moths

shown are specialized on: (A) alder, (B) various species

of Ceanothus, and (C) oak. Photographs by Jeff Miller.

A. Drepana arcuata

B. Drepanulatrix foeminaria

C. Catocala aholibah

(adult) stages as defoliators, decomposers, prey or hosts

to carnivores, and pollinators. The biodiversity of moths

is linked to the ecosystem through their influences on

nutrient cycling, plant population dynamics, and foodweb dynamics (Miller 1993). Most of the moth species

in the forest are specialists (Figure 16) and can feed on

18

Moths

Moths and butterflies are insects that belong to the Order Lepidoptera, and insects, along with spiders,

crustaceans, and some other invertebrates, are all arthropods. Moths, which comprise far more species than

do butterflies, are nocturnal and have threadlike or feathery antennae. In the study reported here, moths were

categorized by functional group based on their food source, which emphasizes one aspect of their function in

the ecosystem (i.e., herbivory). Nearly all moths are plant-feeders in their caterpillar stage, and functional

groups were based on the following host plants: conifers, hardwood trees and shrubs, mixed conifershardwoods, herbs and grasses, and detritus. Moths also can be grouped according to whether they are

specialists or generalists. Specialists require specific circumstances, e.g., a particular food plant, in order to

live, develop, and reproduce. In contrast, generalists can survive under a wide range of conditions, and are

not specialized such that they can live only under a particular set of circumstances—in this case, the

particular food types available.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

only a few, if not one, plant species. If that plant species

is lost from the forest, then the moth and the function

that it provides are lost as well. Thus, patterns in the

biodiversity (i.e., species richness and relative

abundance) of moths are related to the biodiversity of

host plants in forests.

Reciprocally, moths influence plant communities,

and plant communities may change if moth abundances

change. In addition, populations of species that prey on

moths (e.g., some birds and bats) may change if forest

moth abundance and species composition change. Thus,

patterns in moth biodiversity, which can be observed

and used to compare and contrast ecological situations

and practices involved in forest management, have

important implications for other organisms in the

ecosystem. Despite their ecological importance and

potential value as indicators of forest condition, no

policies or mandates exist concerning the management

of moths.

Birds

Natural resource agencies increasingly are including

neotropical migratory birds in conservation

management goals (Finch and Stangel 1993). Forestmanagement practices influence habitat for neotropical

songbirds by altering stand structure (Hansen et al.

1995; Hagar et al. 1996) and landscape patterns

(McGarigal and McComb 1995). Although changes in

the abundance of some species of songbirds have been

observed following forest-management activities such

as thinning, the functional mechanisms underlying these

changes have not been studied. Responses of organisms

on which birds depend for food, e.g., plants and

arthropods (including moths), to forest-management

practices may influence the responses of birds by

influencing food availability.

Although most bird species are not directly

associated with particular plant species, they may be

linked to certain plants through their arthropod prey.

Arthropods are an important part of the diet of most

neotropical migratory birds that breed in forests of the

Pacific Northwest (Ehrlich et al. 1988). Most

arthropods select specific host-plant species (Edwards

and Wratten 1980), and arthropod community

composition changes with stand and tree age, structure,

and size (Jackson 1979; Schowalter 1989). Forestmanagement practices can affect stand structure and

composition, with consequences for arthropods. For

example, commercial thinning can influence cover,

density, and frequency of shrubs in the understory

(Bailey and Tappeiner 1998; Bailey et al. 1998).

Alterations in forest structure that affect understory

shrubs may affect moths and other arthropods (Doolittle

2000), and hence bird populations and communities. In

fact, availability of food may be the ultimate factor

(Hilden 1965) causing changes in bird abundance

related to management-induced changes in stand

structure in forests of the Pacific Northwest. Although

only a few studies have examined changes in bird

abundance in relation to management-induced changes

in stand structure in forests of the Pacific Northwest

(e.g., Hagar et al. 1996; Haveri and Carey 2000), even

fewer have examined how management practices

influence the availability of arthropod prey for

insectivorous forest birds (e.g., Hagar 1993; Weikel

and Hayes 1999).

19

Birds

This study included the resident and

neotropical migratory songbirds, woodpeckers,

and hummingbirds. Songbirds are known also as

the passerines, i.e., the perching birds. Neotropical migratory songbirds migrate across the

United States-Mexico border.
20 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Study Methods

Trees, Shrubs, and Herbaceous Vegetation

Research on trees, shrubs, and herbaceous vegetation

involved inventories of species at several places in each

stand. Approximately ten (6–12) points were

established on a grid at intervals of 50–75 meters in an

interior area (>10 hectares in size) of each stand. The

species, DBH, total height, live-crown ratio, and crown

radius were tallied for each living codominant and

dominant overstory tree with a DBH >20 centimeters at

each center point with variable-radius plots. Five 70.8-

square-meter circular plots, one at the center point and

the others at 15 meters from the center point in each

cardinal direction, were used to inventory understory

trees at each point. Understory trees (2.5–20.0

centimeters DBH and below the main canopy) were

tallied in each of these plots, and tree seedlings (<2.5

centimeters DBH, >15 centimeters in height) were

tallied in smaller, 17.6-square-meter circular subplots

nested within the understory-tree plots. Shrubs were

tallied in the subplots as well, and were segregated into

two layers: tall shrubs (>150 centimeters in height) and

low shrubs (50–150 centimeters in height). Densities

(number of stems per subplot) of tall shrubs were

recorded by species, and percent cover of low shrubs

was estimated visually. Low shrubs included nonwoody

species, such as bracken fern and sword fern, if these

species fell within the bounds of the low-shrub height

class. Percent cover of each herbaceous species was

estimated in several additional 1-square-metersubplots

in each understory-tree plot.

Epiphytic Lichens and Bryophytes

Epiphytic lichens and bryophytes were examined in two

studies: one that focused on all macrolichens present on

both trees and shrubs, and one that considered both

macrolichens and bryophytes on shrubs only.

Macrolichens on Trees and Shrubs

An ocular search for macrolichens on trees and

shrubs was conducted in one 0.38-hectare (34.5-meter

radius) circular plot within each stand. The ocular

search, limited to a 2-hour period, included all

macrolichens on woody vegetation (living or dead) that

were >0.5 meter above the ground and accessible

without climbing trees. The search also included recent

macrolichen litterfall. Coarse abundance ratings (1 = 1–

3 individuals; 2 = 4–10 individuals; 3 = >10 individuals;

4 = occurs on >50 percent of substrate) were assigned to

every macrolichen species found in each circular plot.

In addition, data were gathered on tree species, basal

area, canopy density, and shrub species present.

Macrolichens and Bryophytes on Shrubs

Studies of macrolichens and bryophytes on shrubs

≥2 meters in height included two methods: timeconstrained ocular surveys of a single, large, circular

plot in each stand sampled, and fine-scale cover

estimates made on a subset of tall shrub stems from

each large plot. Ocular surveys were intended to

increase the total number of species sampled, whereas

the finer-scale cover estimates were focused on

detecting relatively small-scale, but potentially

important, differences in abundance (percent cover) of

species. The tall-shrub species sampled included vine

maple, oceanspray, California hazel, and Pacific

rhododendron. Shrubs in the genera Rosa, Rubus, and

Vaccinium, which appeared to provide poor substrate

for epiphytes, were excluded from sampling.

The ocular surveys were constrained to 1.5 hours in

each stand, and the species and abundance class (1 = 1–

3 individuals; 2 = 4–10 individuals; 3 = >10 individuals;

4 = occurs on >50 percent of substrate) of macrolichens

and bryophytes present on tall shrubs were determined

within each large plot. Fine-scale cover estimates were

made on 20 shrub stems, chosen without bias, from

throughout each large plot. A stem microplot, i.e., a 0.5-

meter section centered 1.5 meters from the base of the

stem, was sampled on each shrub stem, and percent

cover (the percentage of the stem microplot occupied by

each macrolichen or bryophyte species) was recorded.

Some stands had <20 tall-shrub stems, and no stemmicroplot surveys were conducted in these stands.

Ocular surveys were made in all stands, except for the

few that lacked tall shrubs entirely. The species,

diameter, age, and life-class group (young whip,

vigorous mature, declining, decadent) of each sampled

stem was recorded. Densities of tall-shrub stems were

estimated by sampling randomly selected subplots (3-

meter radius) within each large plot.

Moths

Moths were sampled 9–12 times a year in each

stand. Sampling involved placing three 22-watt

blacklight traps in one location within each stand

(minimum size = 2–5 hectares) during each sampling

period (Figure 17). Traps within a given plot were

placed 100–150 meters apart. They were operated for

two consecutive nights once every 3 weeks from May

through October. Collections were not made on the 3

days prior to and following the full moon.

Trapping records from each stand type were pooled,

and moths were counted to assess abundance (total

number of individuals collected) and species richness

(number of species) of resident fauna. Moths then were

sorted into functional groups based on their food
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 21

Figure 17. Adult moths were captured at night with an

ultraviolet blacklight trap. Moths were identified,

counted, and sorted into functional groups based on

their food resources. Photograph by Jeff Miller.

resources—conifers, hardwood trees and shrubs,

mixed conifers-hardwoods, herbs and grasses, detritus,

and unknown.

Birds

Data on abundance and community composition of

resident and neotropical songbirds, woodpeckers, and

hummingbirds were gathered during four visits (Ralph

et al. 1995) to at least ten stands each year during three

consecutive early spring–summer seasons. Observations

were made by point counts (Reynolds et al. 1980) at 1–

6 point-count locations in each stand. Point-count

locations were visited between a half hour before and 4

hours after sunrise. This protocol allowed for

comparisons of the abundance of common species (i.e.,

species that occurred in ≥75 percent of the 20 stands)

among stand types. Abundance was calculated as the

mean number of observations per stand per year for

each species, and species richness as the total number

of species observed in each stand per year. Although

bird abundance is not necessarily an indicator of overall

habitat quality (Van Horne 1983), it does provide

information on the stand conditions in which each

species was observed most commonly. Differences in

abundance and species richness among stand types were

analyzed by analysis of variance.

Bird diets were described by identifying arthropod

fragments from fecal material collected from two

species of forest birds mist-netted in the spring (Figure

18). These analyses focused on Swainson’s thrushes

and Wilson’s warblers, because these species forage

primarily in the forest understory, where it was feasible

to capture them and sample food availability (i.e.,

arthropods). Fecal material was stored in alcohol

(Rosenberg and Cooper 1990) pending identification of

arthropod fragments. In addition, arthropods were

collected within 8 days of collecting the fecal samples

to provide a reference collection and estimates of

arthropod availability. Individual branches of foliage

from nine major understory shrub and tree species

(bracken fern, California hazel, Douglas-fir, oceanspray,

salal, salmonberry, sword fern, vine maple, and western

hemlock) were clipped and beaten to dislodge

arthropods. Each beaten branch constituted a sample of

arthropods. The branches themselves were dried and

weighed individually after arthropods were collected to

provide a standardized estimate of arthropod abundance

(number per mass of dried plant material). These shrub,

tree, and arthropod samples allowed comparisons to be

made between the frequency of occurrence (number of

samples of occurrence/total number of samples) of

arthropod orders in bird diets and their frequency and

abundance on understory shrubs and trees.

Figure 18. Swainson’s thrush and Wilson’s warbler were

captured with mist nets. After fecal samples were

collected, the birds were released. Arthropod fragments

then were sorted from the fecal samples and identified.

Photograph by David Vesely.

Variation in the abundance of selected bird species

among stands was modeled (multiple regression) as a

function of vegetation characteristics for the 14 younggrowth stands from which point-count data were

collected. Habitat data (cover of dominant trees, low

and tall shrubs, herbs, and canopy foliage) were

collected at each of the point-count locations. In

addition, stand-level habitat data (from Bailey 1997;

Rosso 2000; and Peterson and McCune 2001) were

used in the analysis.
22 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Study Objectives, Results, and

Recommendations for

Management

Trees, Shrubs, and

Herbaceous Vegetation

Researchers: John Bailey and John Tappeiner10

Study Objectives

The primary objectives of this portion of the

Managing for Biodiversity in Young Forests Project

were to: (1) describe the species composition and

structural development of understory vegetation in

stands typical of young forests in western Oregon, (2)

compare these results to those for understory vegetation

in old-growth stands, and (3) describe the apparent

influence of thinning on young-growth stand structure,

development, and species composition.

Major Findings

Total species richness of herbaceous plants, i.e.,

number of species present, was consistently higher in

thinned stands relative to unthinned and old-growth

stands (Table 3), as was percent cover by herbs. Little

evidence was found for consistent differences in species

composition, especially herbaceous vegetation, among

stand types. Herb communities generally differed more

by geography (location of stands) than by stand type.

All of the native plant species that occurred in the oldgrowth stands, and a few additional species, were found

in the thinned and many of the unthinned young-growth

stands. No species were unique to old-growth stands,

one was unique to unthinned young-growth stands, and

several species were found only in thinned younggrowth stands (Table 3). Although thinned stands had a

greater number of exotic plants than did unthinned or

old-growth stands, including two species that were

found only in thinned stands, exotic plant cover in all

stand types was low.11 Furthermore, only a small

portion of the greater species richness measured in

thinned stands resulted from the presence of exotic

species (Table 3). The numbers of native grasses and

vines, as well as nitrogen-fixing species, also were

greater in thinned stands than in unthinned or oldgrowth stands.

10 Research reported here is based primarily on Bailey (1997). Details on species composition and stand structural development

are reported also in Bailey et al. (1998) and Bailey and Tappeiner (1998), respectively. 11 The range in exotic cover (percent of plot area covered) and frequency (proportion of plots in which a species was found) in

thinned stands was 0.01–0.30 percent and 0.0–0.3, respectively. In old-growth stands, these values were 0.0–0.1 percent and

0.0–0.1, respectively.

The density and frequency of occurrence of conifer

seedlings, primarily western hemlock, were highest in

thinned stands. The higher rate of conifer establishment

in the understory of thinned stands was the largest and

most consistent difference measured between unthinned

and thinned stands (Table 4). Of 32 unthinned-thinned

pairs of young-growth stands, 29 thinned stands had

conifer seedlings in the understory; in contrast, only

seven unthinned stands demonstrated such regeneration.

Conifer seedling density and frequency were strongly

and negatively correlated with shrub cover in thinned

stands. Conifer seedling density and frequency in oldgrowth stands were intermediate between those found

in unthinned and thinned stands. Soil disturbance

associated with thinning, along with the reduction of

overstory density and increased seed production after

Table 3. Herbaceous species richness (number of

species) by stand type across 27 paired unthinned and

thinned young-growth stands and 17 old-growth

stands, with species unique to each stand type (from

Bailey et al. 1998).

S s tand type Specie

richness

Unique species

Unthinned younggrowth 1 d 14 Coastal burnwee

Thinned youngg 3 rowth 1 y 3 Blackcap raspberr

Blue wildryea

Chaparral willowherb

Coastal monkey-flower

Corn lily

Elk clover

Evergreen blackberryb

Groundsel

Lupine speciesc

Ox-eyed daisyb

Pacific water-parsley

Pearly everlasting

Pinesapd

Western waterleaf

O 1 ld-growth 9 e Non

NOTE: Scientific names of vegetation species are given in

Appendix B. a Grass species. b Exotic species. c Nitrogen-fixing species. d Monotropoid species, i.e., nongreen plants that obtain

nutrients through fungi.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 23

thinning, probably played a role in seedling regeneration in thinned stands.

Survival and growth of understory trees, i.e., trees

2.5–20.0 centimeters DBH, were greater in thinned than

in unthinned young-growth stands. Understory trees had

average densities of 158 trees per hectare in thinned

stands, and 88 trees per hectare in unthinned stands. In

thinned stands, understory tree populations comprised

released intermediate or suppressed trees, together with

regenerating western hemlock and western redcedar. In

thinned stands, 83 percent of these stems were alive,

compared to 89 percent in old-growth stands. In

contrast, only 52 percent of the understory trees were

alive in unthinned stands, and comprised suppressed

trees and a few regenerating, shade-tolerant saplings.

Live-crown ratios in thinned stands averaged 66

percent, as compared to averages of 44 percent and 48

percent, respectively, in unthinned young-growth and

old-growth stands.

Similar to findings for most seedling variables, tallshrub characteristics (density, frequency, and leaf-area

index) were more similar between thinned and oldgrowth than between unthinned and old-growth or

between unthinned and thinned young-growth stands

(Table 4). Tall-shrub density generally was higher in

thinned than in unthinned young-growth stands (Table

4), but was more variable than conifer seedling density

and frequency. In pairwise comparisons between the 32

pairs of unthinned-thinned young-growth stands, tallshrub stem density was significantly higher in 14

thinned stands and 5 unthinned stands.

Total low-shrub cover generally was highest in

thinned young-growth stands (Table 4). Thinned stands

had greater low-shrub cover than did unthinned stands

in 16 of the 32 individual unthinned-thinned pairs, and

cover was significantly greater in thinned stands across

the 32 pairs of stands. Total low-shrub cover was

greater in thinned stands than in either unthinned or

old-growth stands for 11 of the 20 stand triads (Bailey

1997). Higher cover by salal and bracken fern in

thinned stands was particularly notable.

Thus, thinning appeared to promote the development

of multilayered stands (Bailey and Tappeiner 1998),

primarily by providing conditions that favored the

establishment of shrubs, hardwoods, and conifers in the

understory after thinning (e.g., see Figure 19), and by

releasing saplings and intermediate-crown class trees in

the stand. The number of seedlings and amount of shrub

cover established depended on stand density, both

before and after thinning, and on the productivity of the

site (Figure 20). Unlike thinned stands, unthinned

stands had very few seedlings or saplings in the

understory, and no or little initial development of a

multilayered stand (Figure 8).

Additional Research

The results of this work were supported by research

extended to 29 additional sites in the central portion of

the Cascade mountains and Coast Range of Oregon, and

to six sites each in the Cascades, Siskiyous, and coastal

forests of southwestern Oregon. The results of these

additional studies were essentially the same as those

given for this study (Poage 2001; Tom Sensenig,

Oregon State University, personal communication).

These studies also compared live-crown and

height:diameter (H:D) ratios of trees in young-growth

stands managed for timber production to those of trees

in old-growth stands (Poage 2001; Tom Sensenig,

Table 4. Stand-level averages for understory characteristics of 32 paired unthinned and thinned younggrowth stands and 20 old-growth stands in western Oregon (from Bailey and Tappeiner 1998).

Characteristic Stand-level averages (standard error)

Y s oung-growth stands Old-growth stand

U d nthinned Thinne

T ) ree seedling density (stems/hectare) 2 ) 32 (4 1 ) ,432 (52 1,010 (57

T ) ree seedling frequency 0 ) .14 (0.01 0 ) .51 (0.01 0.38 (0.02

Tall-shruba d ) ensity (stems/hectare) 1 ) ,336 (28 2 ) ,085 (40 2,429 (67

T ) all-shrub frequency 0 ) .56 (0.01 0 ) .82 (0.01 0.93 (0.02

T ) all-shrub leaf area index 0 ) .23 (0.01 0 ) .44 (0.01 0.42 (0.01

S ) alal cover (%) 1 ) 2 (0.4 2 ) 3 (0.5 10 (1

B ) racken fern cover (%) 2 ) (0.7 7 ) (0.3 1 (0.1

S ) word fern cover (%) 1 ) 7 (0.4 1 ) 3 (0.5 14 (1

O ) regon-grape cover (%) 1 ) 0 (0.3 1 ) 0 (0.5 10 (1

Total low-shrubb c ) over (%) 4 ) 2 (1 5 ) 6 (1 38 (1

L ) ow-shrub leaf area index 0 ) .91 (0.02 1 ) .40 (0.02 0.78 (0.02 a Shrubs >150 centimeters in height. b Shrubs 50–150 centimeters in height.
24 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

A. Gaultheria shallon B. Pteridium aquilinum

C. Acer circinatum D. Vaccinium parvifolium

E. Berberis nervosa

Figure 19. Typical understory vegetation in stands

located in the project study area included: (A) salal, (B)

bracken fern, (C) vine maple, (D) red huckleberry, and

(E) Oregon-grape. Photographs by Joan Hagar (A–D)

and Alyssa Doolittle (E).

Oregon State University, personal communication).

Live-crown ratios averaged about 50 percent or higher

in the old trees, and 30 percent or less in trees in younggrowth stands, depending on stand density and whether

or not the trees had been thinned. Old trees also had low

H:D ratios (often <40–50), which suggests that they are

resistant to disturbance by agents such as wind, fire, and

ice (Wilson and Oliver 2000; Wonn and O’Hara 2001).

In young-growth stands, these ratios were often closer

to 70, which suggests that these trees are relatively

unstable, and have relatively low resistance to wind,

fire, and ice. Thus, thinning may help trees develop

resistance to these environmental variables. Density

management of young-growth stands is important for

growing large, stable trees over much of the landscape.

Conclusions

1. Commercial thinning practices conducted for

timber production apparently helped initiate

development of diverse, multilayered stands, which

should provide habitat for a variety of plant and

animal species. Specifically, thinned young-growth

stands often had better-developed understories and

more tree regeneration than did unthinned younggrowth stands. Furthermore, small trees that had no

commercial value were freed from some level of

competition by thinning, and grew to enhance

forest structure.

2. Thinning practices, particularly relatively heavy

thinnings early in the development of a stand, may

maintain or enhance stand-level, plant species

diversity. For example, species richness for

herbaceous species (Table 3) and total species

richness across trees, shrubs, and herbaceous

vegetation (Bailey et al. 1998) were greater in

thinned stands than in unthinned and old-growth

stands. A portion of this increased species richness

was associated with exotic species, but grasses and

nitrogen-fixing species also were more abundant in

thinned stands. All of the native species that were

found in old-growth stands, plus additional species,

were found in the thinned and many of the

unthinned stands.

3. Many old trees grew rapidly when they were young

(30–100 years), and produced large stems and

crowns. Recent evidence (Tappeiner et al. 1997;

Poage 2001) suggests that old-growth stands

developed with low densities. In contrast, most

young-growth stands in the region today are

developing as dense, uniform, even-sized stands.

Thinning of these dense, young-growth stands is

likely to promote rapid growth of trees with some

characteristics normally associated with old trees in

old-growth stands.

4. Thinning of young-growth stands may be useful

from the perspective of enhancing both wood

production and forest biodiversity.

Recommendations for Management

1. Thin young (<60 years old), dense forests12 that

have regenerated after harvest to promote biodiversity and abundance of understory plants in

young-growth stands.13 Although many years may

be needed to achieve the full benefits of this

practice for biodiversity, thinning simultaneously

allows for commercial wood production.

12 As noted in the video, Managing for Biodiversity in Young Forests (Tappeiner et al. 2000), in some cases, begin thinning at

10–20 years of age, and continue until 40–50 years of age. 13 See similar recommendations in “Epiphytic Lichens and Bryophytes,” “Moths,” and “Birds” in the Study Objectives, Results,

and Recommendations for Management section of this report. Also see Thysell and Carey (2000, 2001).
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 25

2. Modify some thinning practices to maintain or

enhance forest biodiversity. Variable-density

thinning (which also entails leaving some areas

unthinned) will provide habitat for a diversity of

plants.14 Some plants thrive in relatively open

conditions, whereas others find desirable habitat in

relatively closed-canopy forests. Take into account

habitat features, such as remnant old trees, and

hardwood trees and shrubs, such as vine maple,

bigleaf maple, oceanspray, and chinquapin. In

particular, consider protecting the following:

• Large (>50 centimeters in diameter) dead wood

on the forest floor that may be present from the

previous stand.15

• Remnant old trees that provide important

substrate for epiphytes and habitat for other

organisms as well.

• Hardwood trees and shrub species that provide

important substrate for epiphytes, food for

arthropods that are prey for birds, and cavities

for cavity-nesting birds.

3. Pay attention to exotic species that may enter

stands after thinning has taken place.

4. Adapt thinning prescriptions, including variabledensity thinning, to individual site and stand

conditions (e.g., the current stand structure and

species composition, and the vulnerability of the

site to wind and root disease) and specific

management objectives.16

14 Variable-density thinning is likely to be important for other organisms as well. See “Epiphytic Lichens and Bryophytes,”

“Moths,” and “Birds” in the Study Objectives, Results, and Recommendations for Management section of this report. Also

see Carey and Wilson (2001) and Colgan et al. (1999). 15 This wood provides valuable substrate for forest floor bryophytes (e.g., see Rambo and Muir 1998), and habitat for a variety

of animals (see related papers in Ruggiero et al. 1991). 16 For example, the density of stands might vary from about 50 trees per hectare to grow large trees quickly to much higher

densities to maintain habitat for wildlife associated with relatively high canopy cover.

5. Consider multiple thinning entries over time in

some stands, because the canopy may close quickly

in young Douglas-fir forests located on highly

productive sites.

Figure 20. (A) A lightly thinned stand in the Oregon Coast Range. (B) Ten years after thinning,

this site supports abundant sword fern and is developing understory vegetation. Results from

this study suggest that thinning promotes the development of multilayered stands.

Photographs by John Tappeiner.

A B
26 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Epiphytic Lichens and Bryophytes

Macrolichens on Trees and Shrubs

Researcher: Eric Peterson17

Study Objectives

This portion of the project examined species

richness, overall abundance,18 and community

composition of macrolichens in unthinned and thinned

young-growth stands, old-growth stands, and landscapelevel diversity hotspots. The primary objectives were

to: (1) characterize the epiphytic macrolichen

communities, (2) assess whether or not the communities

differed among stand types, (3) determine whether or

not thinned stands supported species or communities

that were more similar to those in old-growth stands

than were those in unthinned young-growth stands, and

(4) examine whether or not particular habitat features

(within-stand features and landscape-level hotspots)

supported unusual species or abundances of epiphytic

macrolichens on trees and shrubs.

Major Findings

A total of 117 macrolichen species (Figure 21) were

collected, 26 of which were indicators for (associated

mostly with) landscape-level hotspots (e.g., riparian

areas, hardwood gaps, and rocky outcrops). Eleven

species were indicators for old-growth stands or old

remnant trees in young-growth stands, one species was

an indicator for thinned, and no species were indicators

for unthinned young-growth stands (Table 5). In

addition to the 26 species that indicated landscape-level

hotspots in general, 2 additional species were associated

mostly with riparian areas, thus bringing the total

number of riparian indicators to 28 species. Of the

remaining macrolichen species, approximately 65

species, mostly foliose lichens, were generalists, and

approximately 20 species, mostly nitrogen-fixing

species, were rare—i.e., found only once or twice.

Species richness ranged from 14 to 51 species per

plot, and the average number of species per stand

differed little among the four stand types. However,

species richness in hotspots was slightly higher (by an

average of five species per stand) in hotspots than in the

other stand types, as expected. Macrolichen community

composition differed strongly among stand types,

particularly for ecologically important species groups

(Table 6). In general, old-growth stands and old

17 Research reported here is based on Peterson and McCune (2000a–b, 2001), and Peterson et al. (2000).

18 Abundance is based on the abundance-class ratings defined in “Study Methods” in the Materials and Methods section of this

report, and is not to be interpreted to represent biomass. These abundance-class ratings also apply to “Macrolichens and

Bryophytes on Shrubs” in the Study Objectives, Results, and Recommendations for Management section of this report.

remnant trees in young-growth stands supported more

forage lichens and cyanolichens than did young forests.

Thinned stands had a slightly greater abundance of

forage lichens and Hypogymnia imshaugii than did

unthinned stands. Richness of macrolichen species

summed across all stands of a given type, however, was

lower for thinned than for unthinned stands, because

thinned stands lacked many species that occurred

infrequently in unthinned young-growth stands. Lower

richness in these thinned young-growth stands may be a

consequence of the homogenization of habitat that often

results from traditional thinning practices, and would

not necessarily result from alternative thinning practices

described in this report.

Hotspots, particularly hardwood gaps, contained a

high diversity of macrolichens. Gaps increase the

availability of sunlight, particularly during the period of

fall through spring when leaves have fallen and

macrolichens are often wetted and, thus, most active

physiologically. During this time, the surrounding forest

probably helps them maintain moisture. Hotspots,

especially those with riparian areas and hardwood gaps,

also hosted a large number of epiphytic macrolichens

not well represented in upland forests. These

macrolichen species included many that are able to fix

nitrogen. In fact, most cyanolichens inhabited

C. Pseudocyphellaria rainierensis

A. Bryoria pseudofuscens

B. Hypogymnia inactiva

Figure 21. Macrolichens were grouped into three

functional groups: (A) forage lichens, (B) matrix lichens,

and (C) cyanolichens. Photographs by Bruce McCune

(A–B) and Jim Riley (C).
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 27

hardwoods or riparian sites. The most notable exception

to this finding was the nitrogen-fixer, Lobaria oregana,

which was associated with old-growth stands and

remnant old trees in young-growth stands.

Although communities in old-growth and hotspot

stands showed distinct differences from those in other

stand types, macrolichen community composition was

quite similar in young-growth stands, whether the stand

was unthinned or thinned. Patterns in macrolichen

community composition were correlated strongly with

climatic gradients. The greatest variation in

composition occurred between stands in the Coast

Range versus the Cascades. These differences between

mountain ranges were greater among young-growth

stands than among old-growth stands, which suggests

that successional dynamics of these epiphytes may

differ between the two ranges.

Conclusions

1. Thinned stands supported a slightly higher

abundance of forage lichens (some of which are

considered to be associated with old-growth stands)

than did unthinned young-growth stands. In

contrast, total species richness summed across all

thinned stands was lower than that summed across

all unthinned stands.

2. Although average species richness per stand

differed little among stand types, the communities

(i.e., the particular species occurring and relative

abundances of each) differed greatly among stand

types. Thus, comparisons of this type should

include community analyses, in addition to simple

measures such as species richness.19 Macrolichen

communities in thinned stands generally were

similar to those in unthinned young-growth stands,

but differed from those in old-growth stands and

landscape-level hotspots.

19 A similar conclusion was reached for shrub epiphytes, moths, and birds. See “Epiphytic Lichens and Bryophytes,” “Moths,”

and “Birds” in the Study Objectives, Results, and Recommendations for Management section of this report.

Table 5. Tree and shrub macrolichen species strongly associated with (indicators for) thinned younggrowth, old-growth, and hotspot stands in western Oregon.

a

H s abitat S t pecie H s abita Specie

T ) hinned young-growth stand Hotspot (continued

H s ypogymnia imshaugii Hypogymnia occidentali

Old-growth stand Hypotrachyna sinuosa

A m lectoria imshaugii Leptogium corniculatu

A m lectoria sarmentosa Leptogium polycarpu

A a lectoria vancouverensis Lobaria pulmonari

H a ypocenomyce anthracophila Lobaria scrobiculat

L a obaria oregana Melanelia subaurifer

N a odobryoria oregana Menegazzia terebrat

P m latismatia herrei Nephroma bellu

Old treeb Nephroma helveticum

A m lectoria imshaugii Nephroma laevigatu

A m lectoria sarmentosa Nephroma resupinatu

A a lectoria vancouverensis Normandina pulchell

C a etraria pallidula Peltigera collin

H a ypocenomyce anthracophila Pseudocyphellaria anomal

H s ypocenomyce friesii Pseudocyphellaria anthraspi

H a ypocenomyce scalaris Pseudocyphellaria crocat

L a etharia vulpina Ramalina dilacerat

L a obaria oregana Ramalina farinace

N a odobryoria oregana Sticta fuliginos

Hotspot Sticta limbata

C a ladonia fimbriata Usnea glabrat

C i ladonia transcendens Usnea wirthi

Fuscopannaria leucostictoides a No macrolichens were indicators for unthinned young-growth stands. b Old tree refers both to trees in old-growth stands and to old remnant trees in young-growth stands.
28 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

20 These include some pin lichens (see Peterson and McCune 2000b).

21 Hardwoods are important for moths and birds also. See “Moths” and “Birds” in the Study Objectives, Results, and

Recommendations for Management section of this report. 22 Variable-density thinning also should foster diverse herb, moth, and bird communities. See similar recommendations for

other organisms studied as part of this project. See also Colgan et al. (1999), Traut and Muir (2000), and Carey and

Wilson (2001).

3. Old-growth stands supported higher species

diversity and abundance of forage lichens and a

higher abundance of Lobaria oregana than did

other stand types.

4. Hotspots supported more rare or unusual

macrolichens, and a higher diversity and abundance

of cyanolichens, than did other stand types.

Recommendations for Management

1. Retain old and relatively mature or structurally

developed trees in young-growth stands. These

trees provide a means to retain and promote the

growth and reinvasion of dispersal- and substratelimited macrolichen species.

2. Allow some young trees to remain on-site for the

long term (e.g., for centuries), where they can

acquire characteristics of old trees. Strong evidence

exists that certain types of macrolichens,

particularly those that are dispersal-limited, simply

need time to colonize, rather than require specific

late-successional stand characteristics. Allowing

some trees to age on the site also will help provide

adequate habitat for certain types of lichens that

depend on particular bark and tree characteristics.20

3. Protect landscape-level hotspots. These areas

provide habitat for, and may help sustain, many

sensitive species, which often are associated with

these unusual forest structures.

4. Retain a legacy of hardwoods and shrubs, and favor

the old shrubs on a site. Hardwoods provide

important habitat for macrolichens, possibly

because macrolichens grow during the wet season,

when hardwood leaves are not present. In

particular, many nitrogen-fixing species are

hardwood-associated, for reasons that are not yet

well understood.21

5. Focus on increasing structural diversity in managed

forests by providing both gaps and dense areas.

Such diversity should foster the development of

diverse macrolichen communities.22

Table 6. Relative abundance and/or species richness of tree and shrub macrolichens in unthinned younggrowth stands compared to thinned young-growth, old-growth, and hotspot stands in the Coast Range and

Cascade mountains of western Oregon. Abundance and/or species richness in the given stand type is noted as

approximately equal to (=), higher than (+), or lower than (-) that found in unthinned young-growth stands.

Species group Relative abundance and/or species richness

Y s oung-growth stands O s ld-growth stand Hotspot

U d nthinned Thinne

C e onventional Variabl a

Hardwood associatesb l = ow - + ++ /

Old-growth associatesc

Dispersal-limitedd l = ow -+ = / + = /

Substrate-limitede l = ow -+ = / + = /

Weedyf i == = = ntermediate

Generalistsg h =+ = + igh

Riparianh l = ow - = =+ /

NOTE: Information in this table has been compiled from this study (see Peterson and McCune 2000a–b, 2001), as well as

from Neitlich and McCune (1997), Ruchty (2000), and Sillett et al. (2000). a Thinned leaving remnant trees, small gaps, and islands of unthinned vegetation. Comparisons in this column are

presumed from this study and studies listed above, and have not been tested specifically. b For example, Leptogium polycarpum, Nephroma laevigatum, and Peltigera collina. c Lichen diversity increases if the forest includes structural diversity provided by older or larger trees. d For example, Alectoria sarmentosa and Lobaria oregana. e For example, Hypocenomyce scalaris, and several species, such as Calicium glaucellum, Chaenotheca laevigata, and

Microcalicium disseminatum, not included in this study. f Pollution-tolerant/fertilization-responsive, e.g., Physcia aipolia, Physconia spp., Xanthoria fallax, and Xanthoria polycarpa. g Good dispersers, occur in both upland and riparian habitats, and are substrate generalists. Species include Cetraria

chlorophylla, most Hypogymnia spp., and most Platismatia spp. h For example, Cetrelia cetrarioides, Platismatia lacunosa, and Ramalina thrausta.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 29

Macrolichens and Bryophytes on Shrubs

Researcher: Abbey Rosso23

Study Objectives

This study focused on epiphytes on shrubs, because

common field observations indicate that epiphytes can

differ markedly between relatively open areas with an

abundance of shrubs and more closed-canopy areas

within young forests. These observations suggest that

relatively open areas with hardwood shrubs and trees

tend to have higher species richness and greater

numbers of species typically associated with old-growth

stands than do more closed-canopy areas within the

same young-growth stand. Central questions were as

follows: (1) Do shrubs in young-growth stands with a

canopy opened by conventional thinning have higher

species richness or support different communities of

epiphytic lichens and bryophytes than shrubs in

unthinned young-growth stands? If so, (2) does

diversity or abundance of old-growth-associated species

differ between unthinned and thinned young-growth

stands? In addition, (3) do landscape-level hotspots

support unique species, or an unusual abundance of

species, and should they be viewed as important areas

to protect for conserving epiphyte biodiversity (and

other ecosystem attributes)?

Major Findings

A total of 139 epiphyte species , 92 macrolichens

(Figure 21) and 47 bryophytes (Figure 22), were found

23 Research reported here is based on Rosso (2000).

on tall shrubs in the 68 forest stands surveyed. Epiphyte

species richness and abundance differed between sites

in the Coast Range and those in the Cascades (see

Figure 12), as well as among the four stand types—

unthinned and thinned young-growth, old-growth, and

hotspot (Table 7). Overall, differences in epiphyte

communities were greater between mountain ranges

than among stand types. In addition, epiphytic

macrolichens appeared to respond differently to

thinning than did bryophytes; their abundance and/or

species richness showed different patterns with regard

to stand type.

Several species were associated with (indicator

species for) particular stand types (Table 8) in that they

exhibited greater frequency and/or abundance in those

stand types. This was true particularly for landscapelevel hotspots, as anticipated. The list of macrolichen

indicators of stand types based on shrub surveys differs

somewhat from that based on surveys of trees and

shrubs (Table 5), because different hosts were included

when trees were sampled. Most similar are lists of

indicators for landscape-level hotspots (compare Table

8 with Table 5).

In the Coast Range, where often relatively few

macrolichens occurred in the understory of unthinned

stands, species richness and abundance (cover) of

macrolichens on shrubs generally were greater in

thinned and old-growth than in unthinned young-growth

stands. Further, species richness and abundance of

macrolichens in thinned stands did not differ

significantly from that in old-growth stands. No

Table 7. Relative abundance and/or species richness of shrub epiphytes in unthinned young-growth

stands compared to thinned young-growth, old-growth, and hotspot stands in western Oregon. Abundance

and/or species richness in the given stand type is noted as approximately equal to (=), higher than (+), or

lower than (-) that found in unthinned young-growth stands.

Species groupa Relative abundance and/or species richness

Y s oung-growth stands O s ld-growth stand Hotspot

U + nthinned Thinned b Thinnedb

Macrolichens

F w orage lichens l ++ + + o

C w yanolichens l=- o =+ + / +

M w atrix lichens l ++ + + o

Bryophytes

Mosses

M m ats m =- + + ediu

T w ufts l + o =- + + /

L m iverworts m =- + + ediu

NOTE: Relative abundance ratings are based on abundance classes used in ocular surveys and on cover classes

from stem microplots. a Species groups are defined in “Study Organisms” in the Materials and Methods section of this report. b Thinned+ is without loss of older shrub stems; Thinned- is with loss of older shrub stems.
30 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

C. Porella navicularis

A. Eurhynchium oreganum

Figure 22. Bryophytes surveyed on shrubs included: (A)

moss mats, (B) moss tufts, and (C) liverworts. Ruler

measurements are in centimeters. Photographs by

Bruce McCune.

difference in bryophyte species richness was apparent

between unthinned and thinned young-growth stands,

and both stand types supported fewer species than did

old-growth stands.

Bryophyte cover on shrubs in the Coast Range was

often lower in thinned than in unthinned young-growth

stands. Bryophyte cover on shrubs in thinned stands in

the Coast Range was significantly lower than in oldgrowth stands, whereas cover in unthinned stands did

not differ significantly from that in old-growth stands.

The thinned stands in the Coast Range supported fewer

relatively old shrub stems than did unthinned youngand old-growth stands, and, because bryophyte cover

was generally greatest on old shrub stems, damage to

shrubs during thinning may have adversely affected

shrub bryophytes.

In the Cascades, total species richness of

macrolichens across all stands was greater than in the

Coast Range. This difference between mountain ranges

may have occurred, at least partly, because Cascades

stands, both unthinned and thinned, supported higher

densities of relatively old shrub stems than did Coast

Range stands. Further, several Coast Range stands

supported too few shrub stems for stem-microplot

sampling. Although ocular surveys were conducted in

these stands (when shrubs were present), epiphyte

species richness would tend to be reduced, simply

because shrub substrate was lacking.

Thinned young-growth stands in the Cascade

mountains did not have greater macrolichen species

richness or cover than did unthinned stands, possibly

because species richness was relatively high in the

young-growth stands in the Cascades before they were

thinned. Macrolichen species richness and cover did not

differ significantly between young- and old-growth

stands in the Cascades. Further, thinning in young

Cascades stands was not associated with a lower density

of relatively old shrub stems, and bryophyte species

richness and cover in these thinned stands were not

lower than in unthinned stands. Bryophyte species

richness did not differ between young- and old-growth

stands; however, old-growth stands tended to have

higher bryophyte cover (although this difference was

not significant statistically).

Hotspots generally had the greatest species richness

of both macrolichens and bryophytes on shrubs.

Richness of cyanolichens was particularly high in

hotspots, and hotspots hosted a relatively large number

of species not found in other stand types (similar to

findings for macrolichens on trees and shrubs). Most

hotspots, especially those with relatively large

abundances of bryophytes and cyanolichens, were

located in riparian zones.

The high species richness and unique composition of

epiphytes on shrubs in riparian areas may be the result

of several factors. Riparian areas typically were

undisturbed relative to other areas within the managed

forests, and relatively undisturbed conditions provide

time for diverse and lush epiphyte communities to

develop. In addition, the microclimate in riparian areas

is often cooler and moister than that in nearby upland

areas, and these conditions favor many epiphytes.

Further, structural features positively associated with

epiphyte species richness, such as hardwoods and

remnant old trees, often are relatively common in

riparian areas. Hardwood trees may influence shrub

epiphytes, particularly by increasing availability of light

during the cool and moist seasons when many epiphytes

are most active physiologically. Remnant old trees also

may contribute species through litterfall or by

propagule dispersal.

Influences of stand age and structure on shrub

epiphytes were assessed by comparing communities

with multivariate tools, which can detect differences in

community composition, and can be used to test for

correlations of environmental factors with those

differences. In general, communities differed more

between mountain ranges than among stand types. The

differences in species composition of macrolichens and

bryophytes between the two ranges may be related, at

least in part, to the age of shrubs, which generally were

older in the Cascades, as well as to climatic and other

B. Orthotrichum lyellii
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 31

differences between the Cascades and the Coast Range.

In the Coast Range, shrub macrolichen communities in

thinned stands were more similar to those in old-growth

stands than were communities in unthinned stands,

whereas shrub bryophyte communities in unthinned

stands were more similar to those in old-growth stands.

In the Cascades, shrub epiphyte communities differed

more by stand location than by stand type, and

distinctions among communities across all unthinned

and thinned young-growth and old-growth stands were

not strong. In general, differences in shrub epiphyte

communities among sites and stands were most strongly

related to shrub characteristics (e.g., age and stem

density), tree characteristics (e.g., percentage basal area

in hardwoods versus conifers, and total tree basal area),

and abiotic site characteristics (e.g., distance from water

and, in the Cascades, elevation).

Conclusions

1. In dense young-growth stands with few epiphytes

in the understory, thinning may have led to

increased diversity and cover (abundance) of

macrolichens on shrubs, and to increases in the

similarity of macrolichen communities on shrubs

between young- and old-growth stands.

2. Macrolichens and bryophytes on shrubs appeared

to respond differently to thinning of the types used

in these stands. Macrolichen species richness may

have increased in response to thinning, whereas

richness of bryophytes was not greater in thinned

than in unthinned young-growth stands.

3. Thinning associated with a loss of old shrub stems

may have had negative effects on some shrub

epiphytes, particularly on the abundance of matforming bryophytes and macrolichens associated

with relatively old shrub stems.

Table 8. Tall-shrub epiphytes in the Coast Range and Cascade mountains of western Oregon strongly

associated witha (indicators for) unthinned and thinned young-growth, old-growth, and hotspot stands.

Species group

Species

Coast

Range

C p ascades Species grou

Species

Coast

Range

Cascades

Unthinned young-growth standsb Hotspots (continued)

Bryophytes Leptogium polycarpum X X

Frullania californica (X) Menegazzia terebrata X

Radula complanata (X) Nephroma laevigatum X

Nephroma resupinatum X X

Thinned young-growth standsc Normandina pulchella X

Macrolichen Peltigera collina ( X X)

Usnea cornuta (X) Pseudocyphellaria anthraspis X ) (X

Sticta fuliginosa ( ) X) (X

O a ld-growth stands Sticta limbat X ) (X

Macrolichens Usnea fulvoreagens X

Alectoria sarmentosa X Usnea wirthii X

Parmelia pseudosulcata X s Bryophyte

Sphaerphorus globosus X Claopodium crispifolium X ) (X

Usnea filipendula g X roup Dicranum fuscescens X

Bryophytes Dicranum howellii X

Antitrichia curtipendula (X) Homalothecium fulgescens X X

Isothecium myosuroides X Homalothecium nuttallii X X

Scapania bolanderi X Hypnum subimponens X X

Leucolepis acanthoneuron X X

H m otspots Orthotrichum pulchellu X

Macrolichens Plagiomnium venustum X

Cladonia fimbriata X Porella navicularis (X)

Cladonia ochrochlora X ) (X Rhytidiadelphus triquetrus X

NOTE: X = p < 0.05; (X) = 0.1 > p > 0.05, where p = the probability that positive association is by chance. a Those epiphytes that occur with greater abundance or frequency in the given stand type than in other stand types. b No macrolichens were indicators for unthinned young-growth stands. c No bryophytes were indicators for thinned young-growth stands.
32 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

4. Landscape-level hotspots (e.g., riparian areas and

hardwood gaps) were rich in shrub epiphytes, and

supported communities that were distinctly

different from those in surrounding forest areas

(similar to findings for epiphytic macrolichens on

trees and shrubs).

5. In addition to stand structure, the age of shrubs and

stands had important relationships to shrub

epiphyte communities.

6. Community composition, which focuses on which

species are present and their relative abundances,

was important for distinguishing differences in

shrub epiphytes among stand types. Species

richness alone tells only part of the story.24

Recommendations for Management

1. Incorporate variable-density thinning prescriptions

that leave both gaps and dense areas. Variability in

overstory density is likely to promote variability in

shrub epiphyte communities.25

2. Minimize impacts of thinning on shrubs,

particularly old shrubs with well-developed

epiphyte cover. Leave a legacy of old shrubs

available on a site. The age of shrub stems is an

important consideration for shrub epiphytes, and

for functions and species that depend on them.26

3. Protect a variety of landscape-level hotspots, both

riparian and upslope, such as rocky outcrops and

hardwood gaps.

4. Collect epiphyte species-abundance data during

studies describing and documenting the condition

of epiphyte communities, and in situations in which

epiphyte communities are to be monitored. Note

that time and funding constraints generally make it

impractical to collect abundance data during

routine predisturbance surveys.

24 These results are similar to findings for macrolichens on trees and shrubs, moths, and birds. See these respective portions of

the Study Objectives, Results, and Recommendations for Management section of this report. 25 Variable-density thinning is recommended for all other organisms studied as part of this project.

26 Shrub age may not be as important for other species as it is for epiphytes. See “Moths” in the Study Objectives, Results, and

Recommendations for Management section of this report.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 33

Moths

Researcher: Jeff Miller

Study Objectives

In this study, abundance, species richness, and

functional groupings of moths were examined to

determine the potential effects of thinning in younggrowth stands of Douglas-fir. In particular, this study

sought to: (1) measure moth abundance and species

richness in four stand types (unthinned and thinned

young-growth, old-growth, and clearcut), (2) compare

moth populations and communities among the stand

types, in part to assess apparent effects of thinning on

these organisms in young-growth stands, (3) establish

baseline data for bioinventory protocol, and (4)

determine whether or not moths have the potential to

serve as a taxonomic/ecological indicator for assessing

forest-management practices, such as thinning.

Major Findings

Most of the 500 species of moths collected (a total

of nearly 15,000 specimens) were uncommon (Table 9;

Figure 23). Singleton and doublet moths27 made up over

half of the total species list. Geometrids (see Appendix

27 Singleton and doublet moths are those for which only one or two, respectively, of a particular moth species is present in

the sample. 28 Common and scientific names of moth families are provided in Appendix D.

29 This expertise is essential for all organisms studied during this project.

D28) and noctuids were the most frequently collected

moth families, and these families were the most

important taxa for ecological comparisons based on

moth abundance (number of specimens collected) and

species-richness values (Figure 24). Expertise in

identification of these species is critical29 for the success

of programs using moths to make ecological

comparisons among various stand types in forests of

western Oregon.

Old-growth stands supported higher moth

abundances (summed across all five old-growth stands)

than did other stand types, and the lowest summed

abundances occurred in clearcuts (Table 9). Summed

abundances were slightly higher in unthinned than in

thinned young-growth stands, although this difference

probably was not statistically significant. Although oldgrowth stands differed from unthinned and thinned

young-growth stands in terms of total moth abundance

and the particular species present, they did not differ in

species richness (number of species collected). Mean

species richness values (and standard errors) were: 217

(22) in unthinned young-growth, 221 (20) in thinned

young-growth, 227 (18) in old-growth, and 196 (33) in

clearcut stands. Unthinned and thinned young-growth

stands also supported nearly equal species richness. The

Table 9. Abundance of moths by family in unthinned and thinned young-growth, old-growth, and clearcut

stands in Douglas-fir forests in western Oregon.

Moth family Abundance (number of moths captured)

Y s oung-growth stands O s ld-growth stand C l learcut Tota

U d nthinned Thinne

G 7 eometers 2 4 ,82 2 9 ,41 3 6 ,43 1 6 ,63 10,31

N 3 octuids 7 3 5 7 5 1 9 0 1 1 1 ,03 3,41

P 1 rominents 3 95 8 2 75 2 32

T 1 igers 1 55 9 1 7 0 1 2 4 32

T 9 ent caterpillars and lappets 2 06 56 04 4 19

T 8 ortricids 1 34 14 91 1 12

P 5 yralids 1 32 73 61 19

T 93 ussocks 1 42 064

T 79 4 hyatirids 1 773

S 22 2 lug caterpillars 2 062

O 47 0 3 ecophorids 1 42

G 2 4 1 29 iant silkworms

H 2 2 4 08 ook-tips

P 0 1 0 67 lumes

E 0 3 2 05 piplemids

H 0 1 0 45 awks

S 0 1 0 01 wifts

T 0 otal 3 0 ,71 3 1 ,41 4 7 ,90 2 8 ,92 14,94
34 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

widest range in species richness across stands of a given

type occurred in clearcuts, and richness depended on

the age and location of the clearcut. Heterogeneity in

the landscape provided by different forest structures and

plant communities was important in enhancing moth

species richness at the site level, because different stand

types supported many different moth species.

Hardwoods were responsible for most of the species

richness in every stand type (Table 10; Figure 25). In

fact, 46 percent of the species collected across all stand

types were associated with hardwoods. Some

hardwoods were associated with a large proportion of

the moth species, whereas others were associated with

relatively few. For example, caterpillars of many species

feed on blueberry, chinquapin, manzanita, oceanspray,

snowbrush, and willow. Oak and alder are important

food sources also. Conversely, relatively few species of

caterpillars feed on the foliage of dogwood and maple.

Figure 23. A representative sample of the species

collected during one trap night at Honey Creek (site 20,

Figure 12). Approximately 500 species (nearly 15,000

specimens) were collected during the moth study.

Photograph by Jeff Miller.

The quantification of the importance of hardwoods for

moth species richness is a novel finding of this study.

Although unthinned and thinned young-growth

stands did not differ in moth abundance or species

richness, they did exhibit differences in the relative

importance of various moth functional groups (Tables

10–11). Unthinned stands supported the lowest

abundance (percentage of moths from a given

functional group in a given stand type) of hardwoodtree-and-shrub-feeders (Table 11). Percentages of

species richness in the hardwood-feeding functional

group in unthinned stands and clearcuts also were

slightly lower than in thinned young- and old-growth

stands, although these differences among stand types

probably were not significant statistically. Coniferfeeders dominated unthinned young-growth stands

(i.e., made up the highest percentage of total individuals

captured), whereas hardwood-feeders dominated

thinned young-growth and old-growth stands (Table

11). Herb-and-grass-feeding species had higher

percentages of total abundance and species richness in

clearcuts than in other stand types.

Regardless of treatment, species functional groups

based on host-plant category, including those for whom

host plants are not known (Figure 26),30 indicated the

following:

• Only 11 percent of moth species depended on

conifers in the Douglas-fir coniferous biome (see

Table 10).

• An average of 46 percent (as high as 75 percent

in individual stands) of moth species depended

on hardwoods.

• An average of 19 percent (up to 25 percent in

individual stands) of moth species depended on

herbaceous plants.

Thus, in a given stand, ~300 of 400 moths may feed on

hardwoods, and only ~40 are likely to feed on conifers.

30 The host plant or plants are not known for every species. In fact, as much as 25–30 percent of species can have unknown host

plants. This number was 40 percent 10 years ago, so research is improving the situation. Nevertheless, information on

dietary habits of moths for which host plants remain unknown would contribute to interpretation of data on species richness

and abundance.

Table 10. Species richness of moths by functional group in unthinned and thinned young-growth, oldgrowth, and clearcut stands in western Oregon.

F s unctional group Species richnes a (% of species captured in stand type)

Y s oung-growth stands O s ld-growth stand C l learcut Tota

U d nthinned Thinne

H 8 ardwood-tree-and-shrub-feeder 4 15 05 74 64

C 7 onifer-feeder 1 71 51 11 11

U 3 nknown 1 71 41 51 71

H 0 erb-and-grass-feeder 1 01 41 02 91

M 9 7 7 66 ixed-conifer-hardwood-feeder

D 1 1 1 11 etritus-feeder a Percentages do not always sum to 100 percent for a given stand type, because data were rounded.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 35

Typically, around 324–400 species were collected

during 1 year across all treatments in a given study area.

These high numbers of species allowed for assessments

of moth presence, absence, and abundance across many

taxa. In addition, differences among stand types in any

single taxon did not overweight statistical analyses.

These high numbers also indicate very high rates of

species turnover. In other words, individuals of a given

species may occur in a few samples, but then are no

longer present as a result of their seasonal biology.

Different species were collected during different

sampling events and seasons.

Relatively few moth species were indicators for

(strongly associated with, by virtue of abundance,

frequency, or both) particular stand types.31 One species

(Zosteropoda hirtipes) was an indicator for clearcuts

across four of the sites (site 16, Figure 12, was

excluded, because it was drier than other areas and

supported many different species than did the other

areas). Another species (Feltia herilis) was an indicator

for clearcuts across three of the sites, and one species

(Cyclophora dataria) was an indicator for old-growth

stands, also across three sites. Eleven other species were

identified as indicator species for various stand types at

two sites.

Moth communities differed more among sites than

among stand types across all sites.32 However, when

communities were contrasted among stand types within

a given site, differences in moth communities among

stand types were significant. As was found for

epiphytes, analyses that focus on the entire moth

community (i.e., that take into account species

composition and relative abundance of species) can be

useful in revealing differences that might be missed by

comparisons of relatively simple measures, such as

species richness.

31 Numbers of indicator species were higher for epiphytes. See “Epiphytic Lichens and Bryophytes” in the Study Objectives,

Results, and Recommendations for Management section of this report. 32 These results are similar to findings for epiphytes.

Conclusions

1. Geometrids and noctuids were the most numerous

moth taxa collected, and thus were the most

important moth taxa for ecological comparisons

based on abundance and species-richness indices.

2. Thinned young-growth stands did not have lower

species richness than did unthinned stands.

However, the functional group composition of

moths did differ between unthinned and thinned

young-growth stands. This difference suggests that

compositional changes took place after thinning,

probably in response to a change in availability of

host plants, particularly of hardwoods.

3. Both abundance and species richness of moths

exhibited seasonal trends. Thus, sampling must

occur frequently throughout the flight season.

Figure 24. (A) Geometrid and (B) noctuid moths, which

belong to the most abundant moth families collected

during the moth study. These two families were the most

important taxa for ecological comparisons based on

abundance and species richness. Both species are

generalists on hardwoods. Photographs by Jeff Miller.

A. Pero mizon

B. Aseptis binotata

Table 11. Abundance of moths by functional group in unthinned and thinned young-growth, old-growth,

and clearcut stands in western Oregon.

Functional groupa Abundanceb (% total number captured)

Y s oung-growth stands O s ld-growth stand C l learcut Tota

U d nthinned Thinne

H 0 ardwood-tree-and-shrub-feeder 4 74 45 65 94

C 5 onifer-feeder 4 13 23 21 13

U 91 nknown 1 711 9

H 34 3 8 erb-and-grass-feeder 1 6

M 4 6 4 44 ixed-conifer-hardwood-feeder a Very few moths (<1 percent) belonging to the detritus feeding group were collected. b Percentages do not always sum to 100 percent for a given stand type, because data were rounded.
36 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

33 Major findings for moths appear to complement results for vegetation, epiphytes, and birds. For example, hardwoods were

important for epiphytic lichens and bryophytes (as substrate and probably through influences on light or moisture regimes),

moths (as food sources), and birds (as hosts for arthropods eaten by birds and as habitat). Results for moths did differ from

those for epiphytes in that the age of the tree or stem did not seem important for moths, whereas older stems were important

for epiphytes. 34 Note that this holds true for other taxa as well.

35 Additional species that are important for epiphytes include vine and bigleaf maple and California hazel. Several of these

species, along with bracken fern, sword fern, salal, and salmonberry, also appear to be important for birds, in part because

they are hosts for arthropods eaten by birds.

B. Antheraea polyphemus

A. Lophocampa argentata

Figure 25. Moths were classified into functional groups

based on food source. Members of these groups

included moths feeding on: (A) conifers, (B) hardwoods,

(C) mixed conifers and hardwoods, (D) detritus, and (E)

herbs and grasses. Although adult moths were captured

in the traps for identification, moths in the larval stage

do the feeding. Photographs by Jeff Miller.

4. Hardwood shrub densities often were higher in

thinned than in unthinned young-growth stands,

and these hardwoods were important food sources

for moths. Caterpillars prefer to feed on fresh

foliage, irrespective of stem age.33

5. Sampling moths in forest ecosystems required the

use of specialized equipment and protocols, such

as frequency of sampling and expertise in the

taxonomy of this relatively less well-studied group

of animals.

Recommendations for Management

1. Maintain a variety of stand types and densities

across the landscape to promote a diversity of plant

species and associated fauna.

2. Ensure taxonomic expertise when dealing with

moth species (e.g., issue contracts for moth work

only to persons known to be competent in moth

taxonomy).34 Also, when designing sampling

protocols for moths, be aware of strong seasonal

trends in moth abundance. Half of all the species

present over a year can be collected from the end of

July through August.

3. Categorize moths by functional groups in addition

to species-based categorizations. Grouping by hostplant categories provides ecologically useful

information, because such groupings are tied

directly to the structure and composition of forests.

4. During thinning and other forest-management

activities, favor plants that support a high number

of caterpillars, e.g., chinquapin and oceanspray, as

well as members of the genera Alnus, Arctostaphylos, Ceanothus, Quercus, Salix, and

Vaccinium.

35 This can be accomplished by

protecting established individuals during thinning

or other forest-management activities. Although it

is not possible to identify a set number of plants to

retain per unit area, any removal of these species

likely will have a corresponding effect on moth

populations and communities.

5. Be aware that a high frequency of uncommon

species in a stand might be a positive indicator of

forest health.

C. Neoalcis californiaria

D. Clemensia albata

E. Peridroma saucia
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 37

Birds

Researchers: Joan Hagar and Ed Starkey36

Study Objectives

This portion of the project assessed diversity

(species richness) and abundance of forest birds in

unthinned and thinned young-, and old-growth stands.

Relationships of bird abundance to both the abundance

and composition of arthropod prey (including moths)

and the structure and composition of understory

vegetation, particularly shrubs, also were examined.

Arthropods have many important functions in forest

ecosystems, including being a significant food resource

for birds.37 Many arthropods depend on hardwood

shrubs for food and habitat.38 Thus, forest-management

activities that affect shrub communities, such as

thinning, may alter the abundance and species

composition of arthropods, which may, in turn,

influence the distribution and abundance of birds that

prey on arthropods.39 Primary objectives for this study

were to: (1) characterize the forest bird communities in

three types of stands (unthinned and thinned younggrowth and old-growth), (2) assess whether or not bird

communities differ among the stand types, (3) identify

the arthropod taxa that are food for shrub-associated

birds, (4) describe associations between these arthropod

taxa and plant species (i.e., define which plant species

support which arthropod taxa), and (5) relate these

findings to forest-management practices that modify

forest structure and composition, and hence availability

of food for forest birds.

36 Research reported here is based on Hagar et al. (1996).

37 Described in the Moths portion of “Study Organisms” in the Materials and Methods section of this report.

38 See the Major Findings portion of “Moths” in the Study Objectives, Results, and Recommendations for Management section

of this report. 39 See results related to shrubs in “Trees, Shrubs, and Herbaceous Vegetation” and “Macrolichens and Bryophytes on Shrubs”

in the Study Objectives, Results, and Recommendations for Management section of this report.

Major Findings

A total of 57 forest bird species were observed in

unthinned and thinned young-growth, and old-growth

stands in the Coast Range during this study (Appendix

E; e.g., Figure 26). Total abundance of birds (total

number of counts per stand per year across all species)

and abundances of 12 individual species differed among

old-growth and unthinned and thinned young-growth

stands (Table 12). Patterns of abundance in relation to

stand type were highly variable among species. In

comparisons of abundance among the three stand types,

more species (six) had peak abundance in old-growth

than in other stand types, whereas none were most

abundant in unthinned, and three species were most

abundant in thinned young-growth stands (Table 12).

Total abundance of birds across species was greater in

both thinned young- and old-growth stands than in

unthinned young-growth stands.

The abundance of Swainson’s thrushes was highest

in both thinned young- and old-growth stands, and did

not differ between these stand types. Hermit warblers

and western tanagers were more abundant in both types

of young-growth than in old-growth stands, and their

abundance did not differ between unthinned and thinned

young-growth stands. The Pacific-slope flycatcher was

the only species with a significantly greater abundance

in unthinned than in thinned young-growth stands,

although peak abundance occurred in old-growth

stands. Hairy woodpeckers, which have been reported

to be associated with old-growth forests (Carey et al.

1991), actually were more abundant in thinned younggrowth stands than in either old-growth or unthinned

Figure 26. Three of the bird species surveyed during the Managing for Biodiversity in

Young Forests Project: (A) Swainson’s thrush, (B) Wilson’s warbler, and (C) western

tanager. Photographs by Bill Dyer, Cornell Laboratory of Ornithology (A), Joan Hagar (B),

and U.S. Geological Survey (C).

A. Catharus ustulatus B. Wilsonia pusilla C. Piranga rubra
38 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

young-growth stands. Only three of the species that

were counted frequently enough for statistical

comparisons showed no differences in abundance

among stand types sampled (Table 12).

A reference collection of arthropods taken from nine

dominant shrub and understory tree species indicated

that arthropod abundance and species composition

varied among shrub species (Table 13). Bracken fern

appeared to support a greater abundance of arthropods

than did other shrub species, and was more abundant

(had higher cover) in thinned young-growth stands than

in other stand types (see Table 4). In general, arthropods

tended to be most numerous in thinned young-growth

stands, though the differences among stand types may

not be significant statistically.

The abundance of Wilson’s warblers, an

insectivorous species that forages in the forest

understory, was strongly and positively associated with

cover of tall hardwood shrubs. Preliminary data indicate

that their abundance also was correlated positively with

arthropod abundance on shrubs. Shrubs are, therefore,

important in providing both cover and food for this

species. The insect parts (e.g., Figure 27) identified in

85 fecal samples indicate that the diet of Wilson’s

warbler comprises primarily flies (Diptera), spiders,

aphids (Homoptera), beetles (Coleoptera), and

caterpillars (Lepidoptera). The taxa found most

frequently in fecal samples from this species were also

the taxa found most frequently on several species of tall

hardwood shrubs and on bracken fern. Bracken fern and

Table 12. Bird abundance in unthinned and thinned young-growth stands and old-growth stands in the

Oregon Coast Range between May and June, 1995 through 1997. Different letters for a given species

indicate that means differ significantly (P < 0.05, ANOVA) between or among the stand types (least

squares means test).

S ) pecies Abundance (counts per stand per year Pa

Y s oung-growth stands Old-growth stand

U d nthinned Thinne

M E ean S n M E ea S n M E ea S

Most abundant in old-growth stands

B 3 rown creeper 1 B . 0 9 .29 1 B . 0 8 .25 2 A . 0 8 .32 0.00

C 9 hestnut-backed chickadee 2 B . 0 7 .29 3 B . 0 6 .41 5 A . 0 1 .44 0.00

P 4 acific-slope flycatcher 5 B . 0 4 .77 3 C . 0 1 .48 8 A . 0 1 .86 0.00

V 9 aried thrush 0 B . 0 7 .27 0 B . 0 3 .20 3 A . 0 1 .61 0.01

W 9 inter wren 5 B . 0 1 .63 6 B . 0 9 .64 7 A . 0 0 .55 0.08

R 1 ed-breasted nuthatch 1 C . 0 0 .27 2 B . 0 9 .38 2 A . 0 8 .43 0.00

More abundant in thinned and old-growth than in unthinned young-growth stands

S 5 wainson’ s thrush 1 B . 0 4 .20 4 A . 0 1 .62 3 A . 0 4 .45 0.00

T 3 otal 3 B 5. 2 5 .25 4 A 7. 2 2 .74 4 A 6. 0 1 .27 <0.00

Most abundant in thinned young-growth stands

W 7 ilson’ s warbler 0 C . 0 9 .17 4 A . 1 6 .10 1 B . 0 1 .29 <0.00

H 8 ammond’ s flycatcher 0 B . 0 9 .20 1 A . 0 2 .35 0 B . 0 2 .08 0.00

H 2 airy woodpecker 0 B . 0 8 .07 0 A . 0 4 .16 0 B . 0 1 .09 0.01

Most abundant in young-growth stands

H 0 ermit warbler 7 A . 0 6 .95 6 A . 0 2 .56 4 B . 0 9 .86 0.04

W 1 estern tanager 1 A . 0 8 .23 1 A . 0 4 .31 0 B . 0 5 .18 0.01

No difference in abundance

H 0 utton’ s vireo 1 2 . 0 0 .2 1 1 . 0 4 .3 0 4 . 0 1 .1 0.13

S 1 teller’ s jay 1 3 . 0 8 .2 1 5 . 0 5 .3 1 7 . 0 0 .2 0.28

G 9 olden-crowned kinglet 1 0 . 0 5 .4 1 6 . 0 8 .3 2 6 . 0 9 .5 0.13 a The probability (P) associated with the test of the hypothesis that abundance does not differ among stand

conditions is based on repeated measures analysis of variance.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 39

some of the tall shrubs (e.g., vine maple, California

hazel, and oceanspray) were species that apparently

responded positively to thinning (i.e., had higher

density or cover in thinned than in unthinned younggrowth stands).40 Some of these tall-shrub species were

identified as important substrate for shrub epiphytes and

as food sources for moths. Thus, thinning young forests,

in part by providing conditions that support understory

plant species, may be important in fostering biodiversity

of epiphytes, moths, and birds in young forests of

western Oregon.

These findings suggest that plant species

composition, presence of a shrub layer, epiphyte cover,

and snag density influence the abundance of some bird

species. Species richness, total abundance of birds, and

the abundance of eight individual bird species were

positively related to the abundance of hardwood trees

and shrubs. In addition, the abundances of goldencrowned kinglet, red-breasted nuthatch, and chestnutbacked chickadee were positively related to variables

describing epiphytes on shrubs (bryophyte cover,

abundance of macrolichens, and species richness of

macrolichens and bryophytes, respectively). Differences

among stands in the abundances of chestnut-backed

chickadee, Swainson’s thrush, and black-headed

grosbeak were related to variables describing amounts

of dead, woody debris (including snags and large

downed logs); the first two species were positively

associated with soft (decay class V) snags, whereas

black-headed grosbeak abundance was positively

associated with soft logs.

Figure 27. Fragments of arthropods fed on by Wilson’s

warbler. Photograph by Robert Peck.

Conclusions

1. The total abundance of birds was greater in thinned

young- and old-growth stands than in unthinned

stands. The relatively well-developed understory

vegetation in both thinned and old-growth stands

(Bailey 1997) provided vertical heterogeneity that

probably best explains this finding.

2. Habitat conditions for most bird species in thinned

young-growth stands differed from conditions in

old-growth stands. Thus, a diversity of stand types

and conditions across the landscape is necessary to

provide habitat for all bird species.

3. Bird species richness was positively associated

with hardwood components of stand structure,

which indicates the important contribution of

hardwoods to stand-level diversity.41

40 See “Trees, Shrubs, and Herbaceous Vegetation” in the Study Objectives, Results, and Recommendations for Management

section of this report, as well as Bailey (1997). 41 The importance of hardwoods for various organisms has been described in other portions of this report.

Table 13. Arthropod abundance on understory plant species in unthinned and thinned younggrowth stands and old-growth stands in the Oregon Coast Range, averaged across

collections from 1996 and 1997. Dashes indicate that no sample was taken from that species

in the stand type indicated.

Understory plant species

Arthropod abundance

(number per 100 grams dried plant material)

Y s oung-growth stands Old-growth stand

U d nthinned Thinne

B - racken fern - 6 1 4 0 3

C - alifornia hazel - -- 84

D - ouglas-fir - -- 4

O 1 ceanspray 5 83 --

S 9 alal 3 44 43

S - almonberry - -- 85

S 8 word fern 6 65 05

V 2 ine maple 3 43 22

W 2 estern hemlock 2 03 43

M 2 ean 4 15 63
40 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

4. Wilson’s warblers were more abundant in thinned

than in unthinned young- or old-growth stands.

Bracken fern supported a high abundance and

diversity of arthropods, including those found to be

part of the diet of Wilson’s warblers, as did several

tall-shrub species.42

5. The relationship between abundance and habitat

quality is unclear for many species. Preliminary

evidence indicates that the abundance of some

birds may be an indicator of habitat quality,

because bird abundance was correlated positively

with the abundance of food (arthropods).

Recommendations for Management

1. Use thinning as a tool to manage young forests to

improve habitat for some bird species, but leave

some unthinned areas for species associated with

dense conifer canopies.43 The size of unthinned and

thinned areas depends on management goals and

objectives, and on the overall landscape context.

Because breeding bird territories often encompass

5–10 hectares, management at this scale, or larger,

likely will be beneficial when providing habitat for

birds is a consideration.

2. Retain and promote the growth of understory and

midstory vegetation, particularly tall shrubs and

other hardwoods. Relatively heavy thinnings and

irregular spacing of residual trees should help

encourage understory development.44

3. Maintain a diversity of stand types and conditions

across the landscape. Results from this study

indicate clearly that no one kind of stand condition

is optimal for all species.45

42 Cover or density of bracken fern and tall shrubs tended to be higher in thinned than in unthinned stands. See “Trees, Shrubs,

and Herbaceous Vegetation” in the Study Objectives, Results, and Recommendations for Management section of this

report, as well as Bailey and Tappeiner (1998). 43 Note that variable-density thinning has been suggested as a tool to enhance biodiversity of other forest organisms studied as

part of this project. See the Recommendations for Management portions of other studies in the Study Objectives, Results,

and Recommendations for Management section of this report. 44 This recommendation to promote the growth of understory vegetation also has been made for epiphytes and moths. See

“Epiphytic Lichens and Bryophytes” and “Moths” in the Study Objectives, Results, and Recommendations for

Management section of this report. 45 A diversity of stand conditions should foster not only diverse bird communities but also diverse communities of other

forest organisms.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 41

Project Conclusions

Common Themes

The Managing for Biodiversity in Young Forests

Project was established in recognition of the need to

understand the probable consequences for forest

biodiversity of contemporary shifts in the goals and

objectives of forest management, and specifically to

explore the contribution of thinning to management of

forests for biodiversity. As noted by Hayes et al. (1997),

“Thinning has traditionally been used to maximize

wood production; incorporating objectives for wildlife

is a relatively new approach in forest management—one

with a great deal of promise but many unanswered

questions.” Thinning young-growth stands in an effort

to promote native biodiversity of all types of organisms

over the long term raises additional questions. The

effectiveness of thinning (of various types) in

promoting the development of understory vegetation,

tree growth and regeneration, and biodiversity of

associated and interdependent organisms must be

evaluated over the long term to provide answers to these

questions. Fortunately, several such long-term studies

are in progress (e.g., Harrington and Carey 1997; Carey

et al. 1999b; Franklin et al. 1999; Carey and Harrington

2001; Reutebuch et al. 2002).

Young-growth stands vary in structure, composition,

and tree density. When young forests are thinned, the

resulting stand structure and composition depend on

past and current tree density, the thinning treatments

used, site conditions, volume of coarse woody debris,

and other factors. Thinning prescriptions vary widely:

some thinnings are heavy, some are light, and some are

variable-density; some retain remnant trees and shrubs,

whereas others do not; and some call for removal of

downed wood, whereas others do not. Interpretation of

studies involving thinned young-growth stands, such as

those presented in this report, is complicated by the

wide range of stand conditions encompassed by the

term, “thinned young-growth stands.” This variability

among stands and site conditions needs to be

considered in evaluating results from these studies, and

in making decisions about appropriate thinning

prescriptions for a given forest stand.

Despite differences in the organisms and conditions

of stands studied, and in the relationships of the various

organisms to existing stand conditions, the conclusions

of the studies that are part of the Managing for

Biodiversity in Young Forests Project exhibit a number

of common themes. Some of the most important of

these common themes are listed as follows:

• Variation in stand conditions, both within stands

and at the landscape level, is important in providing

habitat for a diversity of forest organisms.

• Hardwoods are important for many species,

whether through providing habitat substrate (e.g.,

for epiphytes), food sources (e.g., for moth larvae),

or foraging substrate (e.g., for birds)—or other

habitat conditions. Hardwood shrubs, in particular,

were identified as being important contributors to

forest biodiversity.

• Hardwoods, particularly shrubs, were generally

more abundant in thinned than in unthinned younggrowth stands 10–20 years after thinning.

• The abundance of some types of organisms,

individual species, and functional groups was

sometimes more similar between thinned and oldgrowth stands than between unthinned and oldgrowth stands; however, many exceptions to this

pattern were found. No overall generalization can

be made that thinned stands have an abundance of

organisms or species richness more similar to oldgrowth than do unthinned young-growth stands—at

least in the first 10–25 years after thinning and for

the kinds of organisms studied in this project.

• Analyses of communities, which take into account

species composition and relative abundance of

species, often were better able to reveal differences

among stand types than were comparisons of

summary measures, as, for example, species

richness or abundance.

• Community analyses generally indicated that

communities differed more by geography (site)

than by stand type.

Proposed Thinning Guidelines

Thinning of the young forests surveyed during this

project was completed under forest-management

protocols prevailing 20–30 years ago. At that time,

managers typically made no attempt to provide for

development of shrub cover or multiple layers in the

canopy, and took no special measures to promote

biodiversity. The primary objective was wood

production. Some positive influences of thinning under

these earlier protocols (as inferred retrospectively) on a

variety of forest organisms are apparent, however.

Because of variation in the type and degree of thinning

possible and the existing condition of young-growth

stands, thinning prescriptions clearly need to be

developed on a case-by-case basis (Figure 28).

Nonetheless, based on current understanding of young-
42 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

growth Douglas-fir stands in western Oregon, the

following general management guidelines46 for thinning

are proposed:

• Retain all existing old, remnant trees, snags, and

large woody debris.

• Leave a legacy of large trees with large limbs

extending low into the crown (“wolf trees”).

• Favor hardwood trees across a range of size classes,

including large trees that occupy midcanopy and

higher positions.

• Protect and encourage a legacy of tall hardwood

shrubs, especially those with old stems.

• Leave sufficient understory conifer regeneration,

which, along with hardwoods, will provide for the

development of multistoried stands.

• Create conditions that provide for the presence of

herbs and grasses in forest stands.

• Use variable-density thinning, including heavy

thinning (e.g., to 50 trees per hectare) in portions

of young-growth stands. Heavily thinned areas will

encourage understory development, as well as

development of trees characteristic of those found

in old-growth stands.

• Foster both within-stand and landscape-level

diversity in stand densities; thus, leave some areas

unthinned to provide a wide range of stand

densities at both spatial scales. Studies assessing

responses of biodiversity to various spatial scales

of management are ongoing, and results that can

inform forest management will not be available for

several years. Thus, recommendations for specific

sizes of areas thinned to various degrees and

unthinned areas are not available. Decisions about

spatial scale must be guided by management

objectives and site or stand conditions.

At this time, the impacts on stand structure and

forest biodiversity of thinning young Douglas-fir forests

of western Oregon according to the proposed guidelines

are uncertain; however, results from this project and

others (see Appendixes F–G) suggest that adoption of

these proposed guidelines is likely to enhance native

biodiversity and encourage the development of oldgrowth characteristics in comparison to what is found in

unthinned young-growth stands and those thinned

according to conventional prescriptions.

In 1977, Marion Clawson wrote that “the importance

of forests tend generally to be underestimated in the

United States, but is better understood in the Pacific

Northwest than almost anywhere else in the country.”

This understanding requires ongoing research,

interpretation, application, and evaluation (i.e., adaptive

management; see Figure 4) to further management

goals, such as those set in managing for biodiversity in

young forests. The findings of this project should assist

in planning for management of western Oregon’s young

forests. Although the findings and guidelines from the

Managing for Biodiversity in Young Forests Project

apply specifically to young Douglas-fir forests of

western Oregon, they also may help guide research

direction and focus in forests elsewhere.

46 These guidelines are stated with recognition that some agencies, groups, and individuals already follow similar guidelines in

their management activities. Although these guidelines are based largely on findings from stands ranging from 50 to 120

years in age, the concepts likely apply to younger stands as well. The validity of extrapolating results to younger stands

remains untested at this time.

Figure 28. A thinned Douglas-fir stand with vine maple in the understory. Thinning

prescriptions need to be developed on a site-by-site basis, with consideration of stand

density, age, species composition, history, landscape context, ownership, and

management objectives. Photograph by Jim Riley.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 43

Application of Research Findings

The following text paraphrases some of the dialog from the video,

Managing for Biodiversity in Young Forests (Tappeiner et al. 2000). This

text focuses on implications for land managers and is intended as a

summary of some of the most important findings of the research described

in the video and in preceding sections of this report.

Forest Manager: Joan, given the current emphasis of land-use planning on

maintaining and producing late-successional forests, what implications

do your findings have for managing habitat for forest bird species?

Hagar: Shrubs, hardwood shrubs in particular, seem to be a key component

of forest ecosystems for several species of insectivorous birds. The

vertical heterogeneity provided by well-developed understory vegetation

in both thinned and old-growth stands probably best explained the

greater total abundance of birds in these two stand conditions compared

to unthinned stands. Shrub-associated arthropod species that are

important in the diet of many forest birds also were more abundant in

thinned stands than in other stand types. These findings suggest that

functional vertical heterogeneity involves more than simply a

multistoried conifer canopy; hardwood shrubs are an important

component of this heterogeneity. Maintaining and producing latesuccessional forests may provide habitat for many bird species, as long

as management activities encourage and maintain a significant amount

of shrub cover.

Forest Manager: How important is the thinning of young-growth stands

from the perspective of forest birds?

Hagar: The thinned young-growth stands in my study had greater shrub

cover and greater abundance of shrub-associated arthropod prey species

than did the unthinned stands, and the abundance of several shrubassociated bird species was greater also. My results, and those of others

working on the Managing for Biodiversity in Young Forests Project,

suggest that thinning can be an important way to maintain and promote

shrub development in young conifer stands. Thinning that intentionally

protects and promotes the growth of shrubs can be used to improve

young-forest habitat for shrub-associated birds. Thinning to promote

late-successional habitat also is likely to maintain shrubs in the

understory, which will lead to more structurally and compositionally

diverse stands in the long term.

47 Adapted from: Parish (1949, Historic Oregon, The MacMillan Company),

Dodds (1977, Oregon: a bicentennial history, W.W. Norton and Company),

Dicken and Dicken (1979, Two centuries of Oregon geography. I. The making

of Oregon: a study in historical geography, Oregon Historical Society),

Dicken and Dicken (1982, Two centuries of Oregon geography. II. Oregon

divided: a regional geography, Oregon Historical Society), Clary (1986, Timber

and the Forest Service, University Press of Kansas), O’Donnell (1988, That

balance so rare: the story of Oregon, Oregon Historical Society), Warren and

Ishikawa (1991, Oregon handbook, Moon Publications), Wilkinson (1992,

Crossing the next meridian: land, water, and the future of the West, Island

Press), Jackson and Kimerling (1993, Atlas of the Pacific Northwest, Oregon

State University Press), Dietrich (1995, Northwest Passage: the great Columbia

River, Simon & Schuster), and Wills (1995, A historical album of Oregon, The

Millbrook Press); Mattingly (1997, The Oregon story: logging [education

guide], Oregon Public Broadcasting).

Chronology of Forestry

in Oregon 47

 Thousands of years BP—Native

Americans inhabit the region

now defined as Oregon.

 1780s—Captain John Meares

recognizes the excellence of

Northwest timber for ship

masts and spars.

 1827—The first sawmill is built

in the Pacific Northwest.

 1833—The first shipment of

Oregon timber is sent to China.

 1850s—Four water-powered mills

and the first steam-powered mill

are in operation in Oregon.

Lumber is traded with China,

Hawaii, and Australia.

 1865—The Silverton Fire burns

approximately 400,000 hectares

of timber.

 1868—Much of the Elliott State

Forest burns.

 1870—There are 173 sawmills

in Oregon, 138 of which use

water power.

 1880s—Heavy logging occurs in

the Blue Mountains. Federal

timber is effectively available

for the “taking.”

 1885—The first Northwest paper

mill is built on the Columbia

River at Camas.

 1891—The General Revision Act

allows presidential withdrawal

of forest reserves, but provides

no funding to administer the

reserves. Benjamin Harrison

sets aside the first of the U.S.

forest reserves.
44 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Forest Manager: Can you describe specific thinning prescriptions that

would be most helpful for forest birds?

Hagar: We need to remember that thinned young-growth stands do not

mimic old-growth stands for most bird species, and that we still have

much to learn about relationships of birds to forest conditions. The main

thing we can suggest at this point is to take care to protect shrubs,

particularly the tall shrubs that also support lichens and bryophytes and

those that are important for moths, because many of the moth species

are food for birds. Thinning that maintains the diversity of tree species,

especially thinning that leaves hardwood trees, also is likely to provide

habitat for birds. Fairly heavy thinning and thinning with irregular

spacing of residual trees are most likely to promote the most structurally

and compositionally diverse bird habitat.

Forest Manager: Jeff, from the work you have completed on moths to

date, what top ten species of plants make the moth world run in

these forests?

Miller: The trees and shrubs that are most important for moths in these

forests include the following, all of which are hardwoods: red alder,

green-leaf manzanita, common buckbrush, deerbrush, snowbrush,

chinquapin, oceanspray, Oregon white oak, willow species, and red

huckleberry. Each of these species supports a dozen or more species of

moths. Numerous herbs and grasses are important as well.

Forest Manager: Based on your experience and findings, will thinning

young Douglas-fir forests enhance habitat for moths?

Miller: That depends on the specifics of the thinning prescription used.

Removing all of the hardwoods would have an immediate and

detrimental impact on moth populations, because so many moth species

depend on hardwoods. Removing many of the smaller conifers and

leaving many of the hardwoods probably would benefit moth

populations by favoring the hardwoods and increasing the amount of

light that reaches the understory. This action would enhance herb and

shrub growth and species diversity, and, therefore, enhance the diversity

of moths. Removing many of the smaller conifers and a portion of the

hardwoods would affect moth populations, but the degree of change

would depend on which hardwood species—and in what proportions—

were removed, and on the conditions that then existed in the understory.

Forest Manager: Should we actively consider moths when we are

selecting a prescription for thinning?

Miller: Yes. Moths should be considered in management decision-making

processes. Moths are diverse and fascinating members of the forest

community, and also play valuable roles in forest ecosystems. They are

vital as food for birds and bats, in particular, and for numerous other

organisms. In addition, some moth species are important pollinators and

recyclers of nutrients in forest ecosystems.

Forest Manager: Abbey, why did you study epiphytic lichens and

bryophytes on shrubs in particular?

Rosso: I focused on epiphytes on shrubs for several reasons. First, areas

with an abundance of shrubs can be hotspots of diversity for epiphytes

and other organisms within young-growth stands. Tall shrubs have been

hypothesized to be initial colonization points in young-growth stands for

some old-growth-associated lichens. In addition, tall shrubs are

important substrates for bryophyte mats, which provide habitat for

numerous arthropod species. I also focused on shrubs, because I thought

that understory communities would have a stronger response to thinning

 1892—The first timberland reserve

in Oregon is set aside—Bull

Run Reserve near Portland.

1894—Heavy logging begins in

the Columbia Basin.

1897—The Organic Act recognizes broad federal power, and

allows for fire protection and

limited timber sales. The Forest

Reserve Act expands the

national forest system.

1898—Gifford Pinchot becomes

chief of the Division of Forestry.

1900—Until this time, the lumber

industry in Oregon rates behind

that in Washington and

California, because timber is

inaccessible to available modes

of transportation. Most of the

timber on the lower eastern

slopes of the Coast Range and

the lower western slopes of the

Cascades is already cut. Great

Lakes timber is exhausted and

companies are moving to the

West Coast. Demand for timber

increases in the eastern states.

1900–1910—A period of largescale logging occurs in the

Columbia River Basin. In

Oregon, only Gilliam, Sherman,

and Malheur counties lack

significant timber reserves.

1905—The USDA Forest Service

is created to conserve forest

resources and stabilize markets.

The first plywood plant is built

at St. Johns.

1913—Weyerhaeuser and the

Southern Pacific Railroad

combined own 22.4 percent of

the standing timber located in

western Oregon.

1920s—Logging with oxen is on

the wane.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 45

than would the epiphyte community overall, which includes, of course,

epiphytes in trees.

Forest Manager: Abbey, on one hand, I hear that thinning is a good thing,

and, on the other, that we need to be cautious about thinning. With the

large areas in reserve under the Northwest Forest Plan, and the relatively

small area of thinning that is planned, do we really need to be careful

not to damage existing old shrubs in every thinning? How much does

conservation of epiphyte species depend on thinning actions?

Rosso: The importance of shrub epiphytes to overall epiphyte diversity

varies considerably from site to site, from stand to stand, and among

shrub species. However, if one of the goals of thinning is to enhance

old-growth characteristics in these stands, then the impacts on shrubs

and their epiphyte communities should be considered during all, or

certainly most, thinning operations. Effective enhancement and

conservation of epiphyte biodiversity, as well as that of other types of

organisms such as moths and birds, require that we not only set aside

reserve areas but also change the way we manage our young forests.

These changes include thinning with attention to leaving hardwood trees

and shrubs, remnant trees, snags, and so on.

Forest Manager: Eric, you noted that several lichen species have limited

capability to disperse over long distances. This limitation suggests that

trees that host these lichen species might serve as sources of “inoculum”

for young-growth stands, if the host trees are retained during thinning.

Over what distance is this inoculation likely to occur? In other words,

what is “long distance” to a lichen?

Peterson: For any plant, the ability to colonize a new location drops off

exponentially with distance from the source plant. For many, if not most,

of the lichens that are associated with relatively old stands, even

seemingly short distances can provide a substantial barrier to dispersal.

These lichens tend to have large, heavy propagules that do not go far as

they fall. Although dispersal distance needs to be studied more

completely, we do have some specific information already. For example,

most propagules of Lobaria oregana, which is probably the most

important nitrogen-fixer in old-growth forests, disperse over a distance

of only 5–10 meters. Thus, if you want to provide remnant trees to help

Lobaria oregana colonize a new stand, the trees need to be spaced so

that their crowns are less than 10–20 meters apart. The same is probably

true for the forage lichens, many of which disperse by fragmentation of

relatively large pieces. In addition, dispersal of lichens between stands

becomes a severe problem for many lichens associated with relatively

old stands, because of their large propagules. This kind of dispersal

involves much greater distances than does within-stand dispersal, and

thus relies on rare events and chance. As the distance between the

stands increases, the average frequency of such events easily can exceed

a century.

Forest Manager: John, I always thought I was promoting diversity with

standard commercial thinning prescriptions. What have you learned

from the studies described here, and other work of your own, that would

alter past commercial thinning prescriptions so that we can do a better

job of promoting diversity?

Tappeiner: Our results suggest that commercial thinning can promote

diversity in many cases, and for several kinds of organisms. Current

practices do not need to be changed much. We do have some

recommendations for modifications, however. The major points are that

 1927—The national forests

contribute about 5 percent of

Oregon’s lumber production.

There are 608 lumber mills, 5

paper mills, 64 planing mills,

and 47 furniture factories in

Oregon. Distribution of mills

changes from the Columbia

River to the margins of the

Willamette Valley, Bend,

Klamath Falls, Lakeview, and

LaGrande. Most lumber is

marketed in rough form.

1930s–1950s—The major focus of

the lumber industry moves from

northwest to southwest Oregon.

The Tillamook Fire (in three

separate events, all caused by

logging operations) destroys

140,000 hectares of Oregon’s

finest timber.

1933—The Tillamook Burn, one

of the nation’s worst, destroys

nearly 100,000 hectares of

Oregon’s timber.

1935—The chainsaw is invented.

1937—The theory of sustained

yield is applied to Oregon landgrant forests by the U.S.

Department of the Interior.

1938—Oregon passes Washington

as the leading timber producer

in the nation (Puget Sound

virgin timber already has been

milled). Oregon becomes the

major lumber state in the nation.

late 1930s—The first sawmill is

built in the Willamette Valley.

1941—The shipbuilding boom

begins in Portland. Oregon law

requires reforestation after

timber harvest.

mid-1940s—Conversion of the

lumber industry to a diversified

forest-products industry begins.
46 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

we should periodically evaluate the results of various thinning

prescriptions, and should pay close attention to actions that can further

promote diversity. These actions include the following:

• Favor hardwood trees and shrubs.

• Leave old trees, snags, logs, and large trees that may remain from

the previous stand.

• Vary tree density, and do some very heavy thinning (leave <50

trees per hectare) in portions of stands, especially in relatively

young stands.

• Leave tree species in addition to Douglas-fir (both conifers and

hardwoods) in both Douglas-fir-dominated stands and stands with

more diverse tree-species composition.

• Release conifer and hardwood saplings present in the understory.

• Plant conifers and hardwoods in the understory after heavy

thinning, or in openings when multistoried stands are desired.

• Maintain long crowns, large branches, and low height:diameter

ratios by thinning.

• Leave large trees, conifers other than Douglas-fir, and hardwood

trees at a variable spacing. Focus more on the characteristics and

purpose of the trees being left than on achieving a regular, uniform

spacing of trees.

Forest Manager: John, the researchers who studied epiphytes in this

project have indicated that both hardwood trees and shrubs provide

important habitat for epiphytes in our forests, and they clearly are

important for birds and moths as well. What can you suggest about

retaining these hardwoods during thinning operations from the

silvicultural perspective? Which trees or shrubs should be left? How

many per hectare? And are they likely to slow the growth of conifers in

young-growth stands?

Tappeiner: We can’t prescribe a set number of trees or shrubs to leave, as

that will depend on what is available on the site and other management

considerations. We can suggest that the hardwood trees with old stems

should be left, and that a legacy of the larger shrub stems should be

protected. These larger and older plants are likely to harbor relatively

well-developed lichen and bryophyte communities. Douglas-fir

generally overtops hardwood trees at about 40–50 years in age. So, from

a wood-production point of view, leaving overtopped hardwoods, or

isolated groups of them, likely will have little effect on conifer growth in

young-growth stands.

Forest Manager: The potential increase in exotic species in thinned stands

is of concern to managers. Will we need to initiate an exotic-species

control program if we implement the thinning actions you suggest?

Tappeiner: John Bailey and colleagues found an average frequency of 0.1

percent and an average cover of 0.08 percent of exotic species in thinned

stands. Thus, both frequency and cover of exotics were quite low.

Exotics did occur in some old-growth stands as well, although their

frequency and cover averaged nearly zero percent across the old-growth

stands. So, the potential for exotics to increase in thinned stands should

be considered, though the effects observed to date have been quite

limited and have not warranted any kind of control programs.

Forest Manager: Although the researchers associated with this project did

not focus on organisms that depend on large, dead wood on the forest

floor—that is, coarse woody debris, we know that others have indicated

that it is important for a variety of creatures, as well as for stabilizing the

 1947—Oregon records 1,573

lumber mills.

 1950–late 1970s—Although the

diameter of logs declines, large

quantities of logs are converted

to lumber, plywood, veneer, and

pulp, with moderate variations

in volume year to year.

 1960—The Multiple-Use

Sustained-Yield Act lists five

basic uses of national forests:

“outdoor recreation, range,

timber, watershed, and wildlife

and fish.”

 1962—The Columbus Day storm

causes extensive damage to

forests in Oregon.

1971—The Oregon Forest

Practices Act, the first of its

kind in the United States,

requires resource protection

during logging.

 1975—No large area of timber in

the state is worked on a

sustained-yield basis. Western

Oregon begins to consider

banning exports and using

special methods to encourage

stand regrowth.

 1976—The National Forest

Management Act is passed, thus

providing for harvest practices

that preserve biological diversity

and meet multiple-use

objectives. The act restricts

clearcutting, but does not

prohibit it. In western Oregon,

only Lane and Douglas counties

show an increase in logging;

they account for a third of logs

produced in Oregon.

 1979—The northern spotted owl is

chosen as an “indicator species”

for ancient forests.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 47

 forest floor, providing nutrients to soils, and so forth. You have

suggested that we maintain coarse woody debris that may be present on

the forest floor from the previous stand. Would you also suggest that we

create more of it in young-growth stands by cutting trees and leaving

them as coarse woody debris? Because we are talking about younggrowth stands, many of these trees would be <50 centimeters DBH. I

wonder if we might be better off not cutting them now to preserve the

option for a future downed-wood component? Or would it be better to

cut and leave them now to boost current coarse woody debris volume?

Tappeiner: This action depends on local site conditions and needs.

Thinning will enable remaining trees to grow and provide large dead

wood for the future. Thinning also may reduce the amount of small,

dead wood, if small trees are removed or given space in which to grow.

Some logs can be left on the ground, and trees can be killed to create

snags as part of the thinning process, thus increasing the amount of dead

wood present. I suggest that we grow large trees to provide large logs

and snags that will last, and thus have a better chance of developing

habitat for amphibians, cavity-nesting birds, and so forth. In many

cases, root disease and damage from wind and ice also will provide

dead wood.

Forest Manager: What stand-thinning schedule and prescription would

you recommend for a typical plantation stand of Douglas-fir in a Coast

Range late-successional reserve, if our goal is to promote biodiversity

and develop late-successional forest conditions?

Tappeiner: We need to develop thinning prescriptions on a site-by-site

basis. Variations in stand density, age, species composition, history,

ownership, and management objectives among and within stands need to

be considered carefully for each stand and instance of thinning. General

prescriptions are less likely to yield the results we desire. We also need

to keep in mind that most of the information we have on thinning with

biodiversity enhancement in mind comes from stands that are now 40–

60 years or more in age, and were established after timber harvest. We

don’t have this kind of information yet from thinning very young stands,

or stands that are much older. Even though it is probably reasonable to

assume that the consequences of thinning will be similar in stands of

those ages, that is, for the most part, an untested assumption at the

present time. Nevertheless, I can offer some general comments.

Assuming the stand to be about 15 years old, I would thin some parts

of the stand heavily (to approximately 50 trees per hectare) right now to

favor some large trees. I would do this to ensure that a mixture of

species and stand densities, as well as trees with large stems and long,

full crowns with large branches—which are important for epiphytes and

some other forest organisms, will be present in the future. I would leave

variable distances among trees. Heavily thinning an entire stand all at

once may be too extreme, and would likely foreclose too many options

for the future. These kinds of stands could produce a lot of commercial

wood for 80–100 years or more, while they are developing

characteristics of old-growth forests. Overall, the type of thinning that

we’ve all been describing here, thinning with consideration for

biodiversity, can be used both in late-successional reserves and on

matrix lands.

 1986—The USDA Forest Service

releases proposed management

guidelines for the northern

spotted owl; final guidelines are

released in 1988.

1987—Fires burn 100,000 hectares

of timber, worth ~$97.3 million.

1990—The U.S. Fish and Wildlife

Service lists the northern spotted

owl as a threatened species in

Washington, Oregon, and

northern California. Northern

Spotted Owl v. Lujan holds that

the U.S. Endangered Species

Act requires the U.S. Fish and

Wildlife Service to designate

critical habitat for the owl.

1993—The Forest Conference is

held in Portland, Oregon, and

President Clinton issues a

mandate to break the gridlock

over forest management.

1995—The U.S. Fish and Wildlife

Service approves the Habitat

Conservation Plan proposed for

the Elliott State Forest by the

Oregon Department of Forestry.

Such plans are developed to

provide protection for the

habitat of sensitive species

during land use.

1996—Major fires burn tens of

thousands of hectares of forest

land, much of it in Oregon’s

national forests.

 Present—The amount of timber

harvested in Oregon48 is

declining, as is Asian demand

for Northwest logs. Restrictions

on federal land are greater than

on private land. Approximately

10 percent of old-growth forests,

virtually all on federal land,

remain uncut. Objectives for

forest management focus on

adaptive management of forest

ecosystems and maintenance of

biodiversity and forest health. 48 Every county in the state, except Clackamas, Gilliam, Malheur, Multnomah, and

Sherman, lists lumber, forest products, or forestry as a principal industry.
48 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Acknowledgments

This publication was produced through the

Cooperative Forest Ecosystem Research Program. The

first three authors contributed extensively to the

compilation, synthesis, and presentation of the

information contained in this report. All other authors,

in addition to Pat Muir and John Tappeiner, contributed

study-related information or background material.

Rosanna Mattingly, a contractor with the U.S.

Geological Survey’s Forest and Rangeland Ecosystem

Science Center, wove the material into a coherent

presentation, edited the report, and conducted layout. In

addition to the authors, many others contributed in

notable ways to this report and the video associated

with the report: Rich Bowden, Chris Cadwell, Candace

Cloud, Alyssa Doolittle, Janet Erickson, Doug

Ferguson, Paul Hammond, Ruth Jacobs, Jack Lattin,

George Lienkaemper, Joe Lint, Betsy Littlefield, Bruce

McCune, Pete Oboyski, Gary Parsons, Robert Peck,

Mark Reed, Dana Ross, Abbey Rosso, Andrea Ruchty,

Miranda Ruth, and Charley Thompson. We thank Bruce

McCune and Abbey Rosso for contributing research

findings related to epiphytes and reviewing the report.

We are especially grateful to Rosanna Mattingly and

Ruth Jacobs for the support, insight, and unwavering

commitment that saw the project through to publication.

This publication and the research reported were funded

and partially conducted by the U.S. Geological Survey’s

Forest and Rangeland Ecosystem Science Center.

Oregon State University’s contribution to the research

and reporting was conducted under Cooperative

Agreement 1434-WR-97-AG-00017 (previously 1434-

WR-98-AG-00027 and 1434-WR-98-AG-00028),

Subagreements 97-017-WS-003 and 97-017-WS-004.

The USDI Bureau of Land Management contributed to

the project through thinning activities that established

stands for comparison, help in locating sites, and

feedback during the research and reporting phases. The

reporting was conducted under the auspices of the U.S.

Geological Survey and the Cooperative Forest

Ecosystem Research Program. Impartial reviews of this

report were provided by Robert Alverts, USDI Bureau

of Land Management, Oregon and Washington State

Office, Portland, Oregon; Andrew Carey, USDA Forest

Service, Pacific Northwest Research Station, Olympia,

Washington; and Nancy Wogen, USDI Bureau of Land

Management, Eugene District Office, Eugene, Oregon.

Data sets for Figure 1 were provided by the Forest

Science Data Bank, a partnership between the

Department of Forest Science, Oregon State University,

and the USDA Forest Service Pacific Northwest

Research Station, Corvallis, Oregon. Additional

research for this project was done by Jim Boyle (soils)

and R. Bruce Bury (amphibians).

The Cooperative Forest Ecosystem Research Program

The Cooperative Forest Ecosystem Research (CFER) Program works closely with resource managers,

researchers, and decision-makers to develop and convey information needed to successfully implement

ecosystem-based management at forest stand and watershed scales, especially on lands dominated by young

forests and fragmented by multiple ownerships. Since 1995, the CFER Program has facilitated management

of forest ecosystems on public lands administered by the USDI Bureau of Land Management (BLM) and

other cooperators in western Oregon. Founding cooperators of the CFER Program are the U.S. Geological

Survey’s Forest and Rangeland Ecosystem Science Center; the BLM Oregon State Office; and Oregon State

University’s College of Forestry and College of Agricultural Sciences. The Oregon Department of Forestry

became a member in 1998. Through team-oriented, integrated research, the CFER Program works to provide

forest managers with new information to evaluate current and proposed strategies and practices associated

with management of forest ecosystems, and to facilitate the development of sustainable forest practices.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 49

49 Taken or adapted primarily from FEMAT (1993). In addition, some sections are from other sources, e.g., Mathews (1990),

USDA and USDI (1994), and Helms (1998).

Glossary of Forest Ecology and

Management Terms49

Adaptive management—A continuing process of

planning, monitoring, researching, evaluating, and

adjusting action with the objective of improving

the ability to achieve defined goals. (See Figure 4,

page 5.)

Adaptive management areas—Lands placed in a landuse designation for which adaptive management is

mandated. Although a portion of timber harvest will

come from these lands, they are intended for

development and testing of new management

approaches to integrate ecological, economic, and

other social objectives. Each area (approximately

ten in the Northwest Forest Plan area) has a thinning

prescription with a different emphasis. (See insert,

page 6.)

Administratively withdrawn areas—Areas removed

from the suitable timber base through agency

direction and land-management plans.

Aspect—The direction a slope faces with respect to the

cardinal compass points. For example, a hillside

facing east has an eastern aspect.

Biodiversity—The number and abundance of species

found within a common environment. Biodiversity

also includes the variety of genes, species,

ecosystems, and the ecological processes that

connect them in a common environment. (See insert,

page 5.)

Bryophytes—Mosses, liverworts, and hornworts. (See

insert, page 17.)

Canopy—The foliar cover in a forest stand consisting

of one or several layers. Canopy most often refers to

the uppermost layer of foliage, but can be used to

describe lower layers in a multistoried stand.

Clearcut—A stand harvest in which all or almost all of

the trees are removed in a single cutting. To clear a

stand by removing all or nearly all of the trees.

Coarse woody debris—The woody portion of a tree

that has fallen or been cut and left in the woods.

Coarse woody debris usually refers to pieces at least

50 centimeters in diameter.

Commercial thinning—Any type of thinning that

produces merchantable material at least equal to the

value of the direct costs of harvesting.

Communities—Assemblages of organisms living

together and occupying a given area.

Congressionally reserved areas—Areas that, for

various reasons, have been withdrawn from timber

harvest by an act of Congress, and were withdrawn

before biodiversity became a major concern. These

lands include such areas as national parks and

monuments, wilderness areas, wild and scenic rivers,

national wildlife refuges, and U.S. Department of

Defense lands. (See insert, page 6.)

Conifer—A tree belonging to the taxonomic order

Gymnospermae, and comprising a wide range of

trees that are mostly evergreens. Conifers bear cones

and needle-shaped or scalelike leaves.

Cover—Vegetation used by wildlife as protection from

predators, to mitigate weather conditions, or to

reproduce. Cover also refers to the protection of the

soil and the shading provided to herbs and forbs by

vegetation, or to the area that is occupied by

vegetation or foliage.

Crown—The upper portion of a tree or other woody

plant that carries the main system of branches and

the foliage.

DBH (diameter at breast height)—The diameter outside

the bark of a tree, measured 1.37 meters above the

ground on the uphill side of the tree.

Density—The size of a population in relation to some

unit of space, e.g., the number of trees located in a

given area.

Density management—The cutting of trees for the

primary purpose of widening their spacing so that

growth of remaining trees can be accelerated.

Density management also can be used to improve

forest health and accelerate the attainment of oldgrowth characteristics where maintenance or

restoration of biodiversity is an objective.

Dispersal distance—A straight-line distance that an

individual travels from its point of origin until it

stops dispersing or dies.

Disperse/dispersal—The spread of a species to a new

location, which often occurs at a particular stage in

the life cycle.

Diversity—The number of species in a community or

region; also referred to as species richness. Some

definitions of diversity include a measure of species

relative abundance; however, in this project,

diversity is used to refer to species richness. (See

insert, page 5.)

Ecosystem—A spatially explicit, relatively

homogeneous unit of the Earth that includes all

interacting organisms and components of the abiotic

environment within its boundaries.

Ecosystem management—A strategy or plan to

manage ecosystems such that their composition,

structure, and function will be sustained over the
50 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

long term, as opposed to a strategy or plan for

managing individual species or commodities.

Endangered species—Any species of plant or animal

defined through the U.S. Endangered Species Act as

being in danger of extinction throughout all or a

significant portion of its range.

Epiphytes—Nonparasitic organisms that grow on

plants. (See insert, page 17.)

Exotic plants—Plants that are not native to an area.

Food web—The interlocking pattern of feeding

relationships in a biological community. The

interactions connect the various members of an

ecosystem, and describe how energy passes from

one organism to another.

Forest lands—Lands that are now, or are capable of

becoming, at least 10 percent stocked with forest

trees and that have not been developed for

nontimber use.

Forest management—The practical application of

biological, physical, quantitative, managerial,

economic, social, and policy principles to the

regeneration, management, utilization, and

conservation of forests to meet specified goals and

objectives while also maintaining the productivity

of the forest.

Habitat—The set of environmental conditions,

structure, and composition under which a specific

organism can live, grow, and reproduce.

Hardwood trees—Flowering trees, belonging to the

taxonomic order Angiospermae, with relatively

broad, flat leaves, as compared to conifers or needleleaved trees.

Hotspots—Within-stand or landscape-level areas with

unusual structure, composition, or environment and

the visual appearance of increased diversity. For

epiphytes, landscape-level hotspots include

relatively large hardwood gaps, riparian areas, and

rocky outcrops, whereas within-stand hotspots

include old remnant trees, large wolf trees, old

shrubs, and hardwood trees.

Landscape—A spatial mosaic of several ecosystems,

landforms, and plant communities across a defined

area irrespective of ownership or other artificial

boundaries, and repeated in similar form throughout.

Late-successional reserves—Forests managed to

protect or foster the development of latesuccessional forest conditions, and to provide habitat

for species that depend on late-successional habitat.

(See insert, page 6.)

Lichens—Symbiotic associations between a fungus and

a photosynthetic partner, i.e., green algae,

cyanobacteria, or both. (See insert, page 17.)

Live-crown ratio—The ratio of a tree’s crown length to

the total length of the tree.

Managed forests—Forest lands treated with

silvicultural practices and/or harvested.

Managed late-successional areas—Selected harvest

areas and managed-pair areas. Managed-pair areas

are located in some portions of the northern spotted

owl’s range, where it is necessary to provide

additional protection in the matrix for pairs of owls

and territorial singles. This consists of delineating a

core habitat area, plus additional acreage of suitable

habitat around the core. The acreage to be delineated

around the core varies throughout the range, based

on data for pairs in that area.

Matrix lands—Lands that belong to the matrix landuse allocation for federal forested lands within the

area encompassed by the Northwest Forest Plan (see

Figure 2, page 4). Matrix lands include federal lands

outside of reserves, and are the lands from which the

bulk of timber harvest will be taken. (See insert,

page 6.)

Multilayered (multistoried) stands—Forest stands that

contain trees of various heights and diameter classes,

and, therefore, support foliage at various heights in

the vertical profile of the stand.

Natural regeneration—Trees grown from natural seed

fall or sprouting.

Nitrogen-fixing—Able to convert gaseous nitrogen

into nitrogen-containing compounds that are usable

by plants.

Northwest Forest Plan—A comprehensive strategy for

lands managed by the USDA Forest Service and the

USDI Bureau of Land Management to maintain and

restore late-successional forests, with simultaneous

recognition of their importance to regional

economies. The Northwest Forest Plan is an

outgrowth of President Clinton’s 1993 conference in

Portland, Oregon, to address long-standing public

concern over management of forests in the Pacific

Northwest. At the heart of the management issue

was disagreement over the relative biodiversity of

managed and old-growth forests. An interagency

team of scientists, the Forest Ecosystem

Management Assessment Team (FEMAT),

developed and assessed a variety of forestmanagement alternatives, one of which was

ultimately selected as the Northwest Forest Plan

(USDA and USDI 1994).

Old-growth forests—Forests in the (usually) latesuccessional stage of forest development, with

moderate-to-high canopy closure; multilayered,

multispecies canopies dominated by large overstory

trees; high incidences of large trees, some with

broken tops and other indications of old and

decaying wood (decadence); numerous large snags;
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 51

and heavy accumulations of wood, including large

logs on the ground.

Overstory—That portion of the trees, in a forest of

more than one story, forming the upper or uppermost

canopy layer.

Public lands—Lands for which title and control rest

with a government, i.e., federal, state, regional,

county, or municipal.

Record of Decision—A document separate from, but

associated with, an Environmental Impact Statement

that states the management decision, identifies all

alternatives (including both the environmentally

preferable and preferred alternatives), states whether

or not all practicable means to avoid environmental

harm from the preferred alternative have been

adopted, and, if not, why not.

Regeneration—The seedlings and saplings existing in

a stand; the act of establishing young trees naturally

or artificially.

Reserves—Forest areas withdrawn from acreage used

for timber production. (See insert, page 6.)

Riparian—That which is related to, living or located in

conjunction with, a wetland, the bank of a river or

stream, or the edge of a lake or tidewater. Note that

the riparian community significantly influences, and

is significantly influenced by, the neighboring body

of water.

Riparian reserves—Lands that are withdrawn from

harvest on the basis of their distance from stream

channels or standing bodies of water. They are

located outside of late-successional reserves, and are

managed with similar objectives, as well as aquaticconservation objectives. (See insert, page 6.)

Seedlings—Young plants grown from seeds; for trees,

often less than 2.5 centimeters DBH.

Shrubs—Plants that have persistent woody stems and a

relatively low growth habit, and that generally

produce several basal shoots rather than a single

bole; usually less than 5 meters tall at maturity.

Silvicultural practices—A set of methods used to

modify and manage a forest stand over time to meet

desired conditions and objectives.

Snags—Any standing dead, partially dead, or defective

trees at least 25 centimeters DBH and at least 2

meters tall.

Species—A group of related organisms having common

characteristics and, for those that reproduce sexually,

capable of interbreeding.

Stand—A contiguous group of trees sufficiently

uniform in age-class distribution, composition, and

structure, and growing on a site of sufficiently

uniform quality to be a distinguishable unit.

Standards and Guidelines—The primary instructions

for land managers, and the principles specifying the

environmental conditions or levels to be achieved

and maintained (e.g., USDA and USDI 1994, 2001).

Standards address mandatory actions, whereas

guidelines are recommended actions based on a

land-management decision.

Structure—The arrangement of the parts of an

ecosystem, both vertically and horizontally.

Successional—Of or relating to a series of dynamic

changes by which one group of organisms succeeds

(replaces) another through time. An example is the

developmental series of plant communities, called

seral stages, following a major disturbance.

Survey and manage species—Species for which

survey and manage standards and guidelines are

prescribed. Survey and manage guidelines are

mitigation measures adopted within the Northwest

Forest Plan Record of Decision (replaced with

USDA and USDI 2001) that are intended to mitigate

impacts of land-management efforts on those species

that are closely associated with late-successional or

old-growth forests and whose long-term persistence

is a concern. These measures apply to all land

allocations and require land managers to take certain

actions relative to forest organisms that are rare or

about which little is known. Actions include the

following: manage known sites, survey prior to

ground-disturbing activities, and conduct extensive

and general regional (strategic) surveys.

Sustained yield—The yield that a forest can produce

continuously at a given intensity of management.

Note that sustained-yield management implies

continuous production so planned as to achieve, at

the earliest practical time, a balance between

increment and cutting.

Thinning—See glossary entries for commercial

thinning, density management.

Thinning prescription—A plan of operation that

specifies the purpose for thinning, the density of

trees to remain after thinning, and the kinds of

trees (e.g., species, size, crown and/or stem

characteristics, location) to be left or removed. The

purpose of the prescription may relate to wood

production, understory characteristics, riparian

areas, or other considerations.

Threatened species—Any plant or animal species

likely to become endangered, as defined by the U.S.

Endangered Species Act, throughout all or a

significant portion of its range within the foreseeable future.

Understory—All forest vegetation growing under an

overstory.

Young forests—Forests that generally are <50–80 years

old. (Also referred to as young-growth forests.)
52 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

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Neitlich, P.N. 1993. Lichen abundance and biodiversity

along a chronosequence from young managed stands

to ancient forest. M.S. thesis, University of Vermont,

Burlington, Vermont.

Neitlich, P.N., and B. McCune. 1997. Hotspots of

epiphytic lichen diversity in two young managed

forests. Conservation Biology 11(1):172–182. See

abstract, page 71.

Oliver, C.D., and B.C. Larson. 1996. Forest stand

dynamics (update edition). John Wiley & Sons, Inc.,

New York, New York.

Oregon Department of Forestry. 1999. Annual Reports,

twenty-five year harvest history. Oregon Department

of Forestry, Salem, Oregon.

Peck J.E., and B. McCune. 1997. Remnant trees and

canopy lichen communities in western Oregon: a

retrospective approach. Ecological Applications

7(4):1181–1187. See abstract, page 71.

Peck, J.E., and P. Muir. 2001. Harvestable epiphytic

bryophytes and their accumulation in central western

Oregon. The Bryologist 104(2):181–190.

Peterson, E.B., and B. McCune. 2000a. The value of

hotspots, particularly in riparian zones, for lichen

diversity in the managed forests of western Oregon.

Pages 38–62 in E.B. Peterson. Analysis and

prediction of patterns in lichen communities over the

western Oregon landscape. Ph.D. dissertation,

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Peterson, E.B., and B. McCune. 2000b. Environmental

relations of calicioid lichens and fungi in a

temperate landscape. Pages 63–89 in E.B. Peterson.

Analysis and prediction of patterns in lichen

communities over the western Oregon landscape.
54 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Ph.D. dissertation, Oregon State University,

Corvallis, Oregon.

Peterson, E.B., and B. McCune. 2001. Diversity and

succession of epiphytic macrolichen communities

in low-elevation managed conifer forests in

western Oregon. Journal of Vegetation Science

12(4):511–524.

Peterson, E.B., B. McCune, and J. Rikkinen. 2000.

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poorly understood species. Pages 90–127 in E.B.

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lichen communities over the western Oregon

landscape. Ph.D. dissertation, Oregon State

University, Corvallis, Oregon.

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odyssey to sustaining terrestrial and aquatic

ecosystems—proceedings of the 2001 national

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numbers. The Condor 82:309–313.

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C.J. Ralph, J. Verner, and J.R. Jehl, Jr., editors.

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Cooper Ornithological Society. Allen Press, Inc.,

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relation to stand management in forests of western

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Corvallis, Oregon.

Ruchty, A. 2000. The association of epiphytic

macrolichens and bryophytes with riparian stand

types along a valley continuum, Oregon Coast

Range. M.S. thesis, Oregon State University,

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Ruggiero, L.F., K.B. Aubry, A.B. Carey, and M.H.

Huff, technical coordinators. 1991. Wildlife and

vegetation of unmanaged Douglas-fir forests.

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structure and herbivory in old-growth and

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Sillett, S.C., B. McCune, J.E. Peck, T.R. Rambo, and A.

Ruchty. 2000. Dispersal limitations of epiphytic

lichens result in species dependent on old-growth

forests. Ecological Applications 10(3):789–799. See

abstract, page 72.

Spies, T.A., and J.F. Franklin. 1991. The structure of

natural young, mature, and old-growth Douglas-fir

forests in Oregon and Washington. Pages 91–109 in

L.F. Ruggiero, K.B. Aubry, A.B. Carey, and M.H.

Huff, technical coordinators. Wildlife and vegetation

of unmanaged Douglas-fir forests. General

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Tappeiner, J.C., D. Huffman, D. Marshall, T.A. Spies,

and J.D. Bailey. 1997. Density, ages, and growth

rates in old-growth and young-growth forests in

coastal Oregon. Canadian Journal of Forest Research

27:638–648. See abstract, page 69.

Tappeiner, J., J. Hagar, J. Miller, E. Peterson, A. Rosso,

J. Lint, P. Muir, and M. Reed. 2000. Managing for

biodiversity in young forests [videocassette]. 1155

V-T. Available from: Forestry Media Center, Oregon

State University, Corvallis, Oregon.

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management on understory and overstory vegetation:

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PNW–GTR-488. USDA Forest Service, Pacific

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Thysell, D.R., and A.B. Carey. 2001. Manipulation

of density of Pseudotsuga menziesii canopies:

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remnant trees to vascular undergrowth communities

in the western Cascades: a retrospective approach.

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amendments to Forest Service and Bureau of Land

Management planning documents within the range
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 55

of the northern spotted owl. 1994-589-111/0001.

U.S. Government Printing Office, Washington, D.C.

USDA, and USDI. 2001. Record of Decision and

Standards and Guidelines for amendments to the

survey and manage, protection buffer, and other

mitigation measures Standards and Guidelines.

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Management, Portland, Oregon.

USDI Bureau of Land Management. 1992. Geographic

Information System database: forest age class

distributions. USDI Bureau of Land Management,

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of habitat quality. Journal of Wildlife Management

47(4):893–901.

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ecology of cavity-nesting birds in young forests of

the northern Coast Range of Oregon. The Condor

101(1):58–66.

Wilson, E.O., editor. 1988. Biodiversity. National

Academy Press, Washington, D.C.

Wilson, J.S., and C.D. Oliver. 2000. Stability and

density management in Douglas-fir plantations.

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ratios and stability relationships for four northern

Rocky Mountain tree species. Western Journal of

Applied Forestry 16(2):87–94.
56 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Appendixes
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 57

Appendix A

Researcher Biographies50

50 Photographs in Appendix A are from U.S. Geological Survey files.

John D. Bailey is assistant professor of silviculture at Northern Arizona

University. He received B.S. and M.S. degrees from Virginia Polytechnic

Institute and State University, and his Ph.D. from Oregon State University.

His major interests include silviculture and adaptive ecosystem-based

management. His work with John Tappeiner on trees, shrubs, and

herbaceous vegetation provides the basis for the retrospective research

reported as part of the Managing for Biodiversity in Young Forests Project.

Joan C. Hagar is a Ph.D. student in the department of forest science at

Oregon State University. She received her B.S. in biological aspects of

conservation from the University of Wisconsin-Madison, and her M.S. in

forest ecology from Oregon State University. Her research specialization is

the ecology and management of forest birds, and she contributed that

expertise to this project.

Bruce McCune is professor of botany and plant pathology at Oregon State

University. He received B.S. and M.S. degrees in botany from the University

of Montana at Missoula, and his Ph.D. in plant ecology from the University

of Wisconsin-Madison. His research focus is the ecology of temperate forest

epiphytes, particularly the ecology and taxonomy of lichens, and the

development of efficient quantitative methods for their study. He also is

interested in describing and understanding change in vegetation in response

to disturbance and stress. He served as major and co-major professor,

respectively, for the Ph.D. work of Eric Peterson and Abbey Rosso.

Jeffrey C. Miller is professor of entomology at Oregon State University’s

College of Agriculture, Agricultural Experiment Station, and College of

Science. While at Oregon State University (since 1979), he has worked on

insect pests of strawberry, wheat, cherry, filbert, alfalfa, peppermint,

broccoli, and forests. In addition, he has studied beneficial insects (e.g.,

parasitic wasps and lady beetles) for use as biological control agents. His

primary research interests are insect ecology and natural history, with

emphases on trophic relationships, systematics, and biogeography. He

studied forest moths as part of this project.

Patricia S. Muir has worked at Oregon State University since 1987, and is

professor of botany and plant pathology and director of the environmental

sciences undergraduate program. She received her B.S. in botany and

biology from the University of Montana at Missoula, and her Ph.D. in plant

ecology from the University of Wisconsin-Madison. Her major research

interest focuses on effects of alternative management systems on forests and

forest ecology. The effects of air pollution on vegetation have been the focus

of past research. She served as co-major professor for Abbey Rosso in her

Ph.D. work.
58 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Eric B. Peterson graduated from Humboldt State University, California,

with a B.S. in botany and environmental biology, and from Oregon State

University with a Ph.D. in plant ecology. Much of the research for his Ph.D.

dissertation on lichens was conducted as part of this project. He is currently

plant ecologist for the Nevada Natural Heritage Program in Carson City,

Nevada. His research interests include the biodiversity and biogeography

of plants and lichens, with particular focus on modeling their occurrence

and distribution.

Abbey L. Rosso received a B.A. from Cornell University; an M.S. from

Scripps Institute of Oceanography, University of California, San Diego; and

a Ph.D. in plant ecology from Oregon State University. Her areas of interest

include lichen ecology and the effects of forest management on communities

of lichens and bryophytes. Much of the research for her Ph.D. dissertation

on lichens and bryophytes was conducted as part of this project.

Edward E. Starkey is research biologist for the U.S. Geological Survey’s

Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon. He

received his B.S. and M.S. from Bemidji State College and St. Cloud State

College, respectively, in Minnesota. His Ph.D. is from Washington State

University. He has worked on a variety of projects, including riverdependent birds of Olympic National Park, deciduous trees and shrubs as

nutrient sources for aquatic organisms, and implications of forest

management on forage for herbivores. He was project leader for the

Managing for Biodiversity in Young Forests Project.

John C. Tappeiner II is a retired forest ecologist with the U.S. Geological

Survey, and currently professor of forest ecology and silviculture at Oregon

State University. He has taught and conducted research in silviculture and

forest ecology for over 20 years. His primary research interests include the

development of old-growth stands, understory establishment and growth in

young-growth stands, shrub and hardwood ecology, and vegetation

management for regeneration. He served as major professor for John Bailey

during his Ph.D. work on vegetation, which was conducted in the project

study sites.
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 59

Appendix B

Common and Scientific Names of Vegetation Referenced in Text

C e ommon name Scientific nam

Bigleaf maple Acer macrophyllum

Blackcap raspberry Rubus leucodermis

Blue wildrye Elymus glaucus

Blueberry Vaccinium spp.

Bracken fern Pteridium aquilinum

California hazel Corylus cornuta var. californica

Chaparral willowherb Epilobium minutum

Chinquapin Chrysolepis chrysophylla

Coastal burnweed Erechtities minima

Coastal monkey-flower Mimulus dentata

Common buckbrush Ceanothus cuneatus

Corn lily Veratrum californicum

Deerbrush Ceanothus integerrimus

Dogwood Cornus spp.

Douglas-fir Pseudotsuga menziesii

Elk clover Aralia californica

Evergreen blackberry Rubus laciniatus

Grand fir Abies grandis

Green-leaf manzanita Arctostaphylos patula

Groundsel Senecio triagularis

Lupine Lupinus spp.

Manzanita Arctostaphylos spp.

Maple Acer spp.

Oceanspray Holodiscus discolor

Oregon white oak Quercus garryana

Oregon-grape Berberis nervosa

Ox-eyed daisy Chrysanthemum leucanthemum

Pacific madrone Arbutus menziesii

Pacific rhododendron Rhododendron macrophyllum

Pacific water-parsley Oenanthe sarmentosa

Pearly everlasting Anaphalis margaritacea

Pinesap Hypopitys monotropa

Red alder Alnus rubra

Red huckleberry Vaccinium parvifolium

Salal Gaultheria shallon

Salmonberry Rubus spectabilis

Snowbrush Ceanothus velutinus

Sword fern Polystichum munitum

Tanoak Lithocarpus densiflorus

Vine maple Acer circinatum

Western hemlock Tsuga heterophylla

Western redcedar Thuja plicata

Western waterleaf Hydrophyllum occidentalis

Willow Salix spp.
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Appendix C

Taxonomy Resources

Trees and Shrubs

Franklin, J.F., and C.T. Dyrness. 1988. Natural vegetation of Oregon and Washington (revised

and enlarged edition). Oregon State University Press, Corvallis, Oregon.

Hitchcock, C.L., and A. Cronquist. 1973. Flora of the Pacific Northwest: an illustrated manual.

University of Washington Press, Seattle, Washington.

USDA, NRCS. 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant

Data Center, Baton Rouge, Louisiana.

Epiphytic Lichens and Bryophytes

Lawton, E. 1971. Moss flora of the Pacific Northwest. The Hattori Botanical Laboratory,

Nichinan, Miyazaki, Japan.

McCune, B., and L. Geiser. 1997. Macrolichens of the Pacific Northwest. Oregon State

University Press, Corvallis, Oregon.

Moths

Miller, J.C. 1995. Caterpillars of Pacific Northwest forests and woodlands. FHM–NC-06-95.

USDA Forest Service, National Center of Forest Health Management, Morgantown, West

Virginia.

Miller, J.C., and P.C. Hammond. 2000. Macromoths of Northwest forests and woodlands.

FHTET–98-18. USDA Forest Health Technology Enterprise Team, Morgantown, West

Virginia.

Birds

American Ornithologists’ Union. 1998. Check-list of North American birds: the species of birds

of North America from the Arctic through Panama, including the West Indies and Hawaiian

Islands. 7th edition. American Ornithologists’ Union, Washington, D.C.

60
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS 61

Appendix D

Common and Scientific Names of Moth Families Referenced in Text

C e ommon name Scientific nam

E e piplemids Epiplemida

G e eometers Geometrida

G e iant silkworms Saturniida

H e awks Sphingida

H e ook-tips Drepanida

N e octuids Noctuida

O e ecophorids Oecophorida

P e lumes Pterophorida

P e rominents Notodontida

P e yralids Pyralida

S e lug caterpillars Limacodida

S e wifts Hepialida

T e ent caterpillars and lappets Lasiocampida

T e hyatirids Thyatirida

T e igers Arctiida

T e ortricids Tortricida

T e ussocks Lymantriida
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Appendix E

Common and Scientific Names of Birds Recorded During Surveys

C e ommon name Scientific nam

American crow Corvus brachyrhynchos

American goldfinch Carduelis tristis

American robin Turdus migratorius

Band-tailed pigeon Columba fasciata

Belted kingfisher Ceryle alcyon

Bewick’ s wren Thryomanes bewickii

Black-headed grosbeak Pheucticus melanocephalus

Black-throated gray warbler Dendroica nigrescens

Blue grouse Dendragapus obscurus

Brown creeper Certhia americana

Brown-headed cowbird Molothrus ater

Bushtit Psaltiparus minimus

Chestnut-backed chickadee Poecile rufescens

Common nighthawk Chordeiles minor

Common raven Corvus corax

Dark-eyed junco Junco hyemalis

Evening grosbeak Coccothraustes vespertinus

Golden-crowned kinglet Regulus satrapa

Gray jay Perisoreus canadensis

Hairy woodpecker Picoides villosus

Hammond’ s flycatcher Empidonax hammondii

Hermit thrush Catharus guttatus

Hermit warbler Dendroica occidentalis

House wren Troglodytes aedon

Hutton’ s vireo Vireo huttoni

MacGillivray’ s warbler Oporornis tolmiei

Marbled murrelet Brachyramphus marmoratus

Mountain quail Oreortyx pictus

Mourning dove Zenaida macroura

Northern flicker Colaptes auratus

Northern pygmy-owl Glaucidium gnoma

Olive-sided flycatcher Contopus cooperi

Orange-crowned warbler Vermivora celata

Pacific-slope flycatcher Empidonax difficilis

Pileated woodpecker Dryocopus pileatus

Pine siskin Carduelis pinus

Purple finch Carpodacus purpureus

Red crossbill Loxia curvirostra

Red-breasted nuthatch Sitta canadensis

Red-breasted sapsucker Sphyrapicus rubber

Rufous hummingbird Selasphorus rufus

Song sparrow Melospiza melodia

Spotted towhee Pipilo maculatus

Steller’ s jay Cyanocitta stelleri

Swainson’ s thrush Catharus ustulatus

62
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

C e ommon name Scientific nam

Tree swallow Tachycineta bicolor

Varied thrush Ixoreus naevius

Vaux’ s swift Chaetura vauxi

Warbling vireo Vireo gilvus

Western screech owl Otus kennicottii

Western tanager Piranga rubra

Western wood-pewee Contopus sordidulus

White-crowned sparrow Zonotrichia leucophrys

Willow flycatcher Empidonax traillii

Wilson’ s warbler Wilsonia pusilla

Winter wren Troglodytes troglodytes

Wrentit Chamaea fasciata

63
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

Appendix F

Recommended Resources for Additional Information

Articles and Books

Assmann, E. 1970. The principles of forest yield study: studies in the organic production,

structure, increment and yield of forest stands, translated by S.H. Gardiner. Pergamon

Press, New York, New York. Summarizes the European experience in forest growth and

stand density.

Bailey, J.D., and J.C. Tappeiner. 1998. Effects of thinning on structural development in 40- to

100-year-old Douglas-fir stands in western Oregon. Forest Ecology and Management 108:99–

113. See abstract, page 68.

Bailey, J.D., C. Mayrsohn, P.S. Doescher, E. St. Pierre, and J.C. Tappeiner. 1998. Understory

vegetation in old and young Douglas-fir forests of western Oregon. Forest Ecology and

Management 112:289–302. See abstract, page 68.

Carey, A.B., J. Kershner, B. Biswell, and L. Dominguez de Toledo. 1999. Ecological scale and

forest development: squirrels, dietary fungi, and vascular plants in managed and unmanaged

forests. Wildlife Monographs 142:1–71. Compares flying squirrels and Townsend’s chipmunks

in southwestern Oregon.

Carey, A.B., B.R. Lippke, and J. Sessions. 1999. Intentional systems management: managing

forests for biodiversity. Journal of Sustainable Forestry 9(3/4):83–125. Provides a computer

simulation of management strategies for Pacific Northwest western hemlock forests.

Chambers, C.L., W.C. McComb, and J.C. Tappeiner II. 1999. Breeding bird responses to three

silvicultural treatments in the Oregon Coast Range. Ecological Applications 9(1):171–185.

See abstract, page 75.

Colgan III, W., A.B. Carey, J.M. Trappe, R. Molina, and D. Thysell. 1999. Diversity and

productivity of hypogeous fungal sporocarps in a variably thinned Douglas-fir forest.

Canadian Journal of Forest Research 29(8):1259–1268. Evaluates the use of ecosystem

management techniques for truffles.

Curtis, R.O., and D.D. Marshall. 1986. Levels-of-growing-stock cooperative study in Douglas-fir:

Report No. 8—the LOGS study, twenty year results. Research Paper PNW–RP-356. USDA

Forest Service, Pacific Northwest Research Station, Portland, Oregon. Summarizes Douglasfir growth and stand development in western Oregon and Washington.

Curtis, R.O., and D.D. Marshall. 1993. Douglas-fir rotations—time for reappraisal? Western

Journal of Applied Forestry 8(3):81–85. Discusses the growth of older Douglas-fir stands.

Daniel, T.W., J.A. Helms, and F.S. Baker. 1979. Principles of silviculture. McGraw-Hill, New

York, New York. Serves as a textbook in silviculture and discusses stand growth.

Dirks-Edmunds, J.C. 1999. Not just trees: the legacy of a Douglas-fir forest. Washington State

University Press, Pullman, Washington. Portrays a Douglas-fir forest in Oregon’s Coast

Range from the 1930s, through logging in the 1960s and clearcutting in the 1980s.

Drew, T.J., and J.W. Flewelling. 1979. Stand density management: an alternative approach and its

application to Douglas-fir plantations. Forest Science 25(3):518–532. Reviews the

development of stand-density diagrams.

Eldredge, N. 1998. Life in the balance: humanity and the biodiversity crisis. Princeton University

Press, Princeton, New Jersey. Outlines steps to be taken as a global society to find a path

away from impending extinctions.

Hagar, J.C., W.C. McComb, and W.H. Emmingham. 1996. Bird communities in commercially

thinned and unthinned Douglas-fir stands of western Oregon. Wildlife Society Bulletin

24(2):353–366. See abstract, page 75.

Halpern, C.B., and T.A. Spies. 1995. Plant species diversity in natural and managed forests of the

Pacific Northwest. Ecological Applications 5(4):913–934. Presents data from permanent-plot

64
MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

and chronosequence studies to describe early responses of understory communities to forest

harvest and potential impacts of post-harvest practices.

Halpern, C.B., S.A. Evans, C.R. Nelson, D. McKenzie, D.A. Liguori, D.E. Hibbs, and M.G.

Halaj. 1999. Response of forest vegetation to varying levels and patterns of green-tree

retention: an overview of a long-term experiment. Northwest Science 73:27–44. Describes

background vegetation studies, provides characteristics of Demonstration of Ecosystem

Management Options study sites and variables, and reviews retrospective analyses and

simulation models.

Hammond, P.C., and J.C. Miller. 1998. Comparison of the biodiversity of Lepidoptera within

three forested ecosystems. Annals of the Entomological Society of America 91(3):323–328.

See abstract, page 72.

Haveri, B.A., and A.B. Carey. 2000. Forest management strategy, spatial heterogeneity, and

winter birds in Washington. Wildlife Society Bulletin 28(3):643–652. Presents the effects of

management strategy and experimental variable-density thinnings on wintering birds in

second-growth Douglas-fir stands.

Hayes, J.P., S.S. Chan, W.H. Emmingham, J.C. Tappeiner, L.D. Kellogg, and J.D. Bailey. 1997.

Wildlife response to thinning young forests in the Pacific Northwest. Journal of Forestry

95(8):28–33. See abstract, page 69.

Lesica, P., B. McCune, S.V. Cooper, and W.S. Hong. 1991. Differences in lichen and bryophyte

communities between old-growth and managed second-growth forests in the Swan Valley,

Montana. Canadian Journal of Botany 69:1745–1755. See abstract, page 70.

Marshall, D.D. 1991. The effects of thinning on stand and tree growth in a young, high site

Douglas-fir stand in western Oregon. Ph.D. dissertation, Oregon State University, Corvallis,

Oregon. Synthesizes long-term stand development at the Hoskins site in western Oregon.

McCune, B. 1994. Using epiphyte litter to estimate epiphyte biomass. The Bryologist 97(4):

396–401. Evaluates the use of litterfall for estimating lichen biomass when large differences

are expected.

McCune, B. 2000. Lichen communities as indicators of forest health. The Bryologist 103(2):353–

356. Overviews systematic documentation of lichen communities in the United States through

the Forest Health Monitoring program.

McCune, B., K.A. Amsberry, F.J. Camacho, S. Clery, C. Cole, C. Emerson, G. Felder, P. French,

D. Greene, R. Harris, M. Hutten, B. Larson, M. Lesko, S. Majors, T. Markwell, G.G. Parker,

K. Pendergrass, E.B. Peterson, E.T. Peterson, J. Platt, J. Proctor, T. Rambo, A. Rosso, D.

Shaw, R. Turner, and M. Widmer. 1997. Vertical profile of epiphytes in a Pacific Northwest

old-growth forest. Northwest Science 71(2):145–152. Describes vertical stratification of

epiphytes by functional group in Northwest forests and evaluates methods used to estimate

their abundance.

McCune, B. 1993. Gradients in epiphyte biomass in three Pseudotsuga–Tsuga forests of different

ages in western Oregon and Washington. The Bryologist 96(3):405–411. See abstract,

page 70.

Miller, J.C. 2000. Monitoring the effects of Bacillus thuringiensis kurstaki on nontarget

Lepidoptera in woodlands and forests of western Oregon. Pages 277–286 in P.A. Follett and

J.J. Duan, editors. Nontarget effects of biological control. Kluwer Academic Publishers,

Boston, Massachusetts. Synthesizes research on nontarget Lepidoptera and provides

recommendations for maintaining biodiversity.

Miller, J.C. 1990. Field assessment of the effects of a microbial pest control agent on nontarget

Lepidoptera. American Entomologist 36(2):135–139. See abstract, page 73.

Miller, J.C. 1990(92). Effects of a microbial insecticide, Bacillus thuringiensis kurstaki, on

nontarget Lepidoptera in a spruce budworm-infested forest. Journal of Research on the

Lepidoptera 29(4):267–276. See abstract, page 73.

65
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Miller, J.C. 1993. Insect natural history, multi-species interactions and biodiversity in

ecosystems. Biodiversity and Conservation 2:233–241. See abstract, page 74.

Miller, J.C. 1995. Caterpillars of Pacific Northwest forests and woodlands. FHM–NC-06-95.

USDA Forest Service, National Center of Forest Health Management, Morgantown, West

Virginia. See abstract, page 74.

Miller, J.C., and P.C. Hammond. 2000. Macromoths of Northwest forests and woodlands.

FHTET–98-18. USDA Forest Health Technology Enterprise Team, Morgantown, West

Virginia. See abstract, page 74.

Neitlich, P.N., and B. McCune. 1997. Hotspots of epiphytic lichen diversity in two young

managed forests. Conservation Biology 11(1):172–182. See abstract, page 71.

Oliver, C.D., and B.C. Larson. 1996. Forest stand dynamics (update edition). John Wiley & Sons,

Inc., New York, New York. Serves as a widely recognized text on forest stand development.

Peck, J.E., and B. McCune. 1998. Commercial moss harvest in northwestern Oregon: biomass

and accumulation of epiphytes. Biological Conservation 86:299–305. Overviews moss

harvest and provides recommendations for adaptive management to protect the harvestable

moss resource.

Peck, J.E., and B. McCune. 1997. Remnant trees and canopy lichen communities in western

Oregon: a retrospective approach. Ecological Applications 7(4):1181–1187. See abstract,

page 71.

Pettersson, R.B., J.P. Ball, K.-E. Renhorn, P.-A. Esseen, and K. Sjoberg. 1995. Invertebrate

communities in boreal forest canopies as influenced by forestry and lichens with implications

for passerine birds. Biological Conservation 74:57–63. Describes impacts of commercial

forestry in decreasing nonmigratory bird numbers through reduced forests and foraging

habitat quality.

Ruggiero, L.F., K.B. Aubry, A.B. Carey, and M.H. Huff, technical coordinators. Wildlife and

vegetation of unmanaged Douglas-fir forests. General Technical Report PNW–GTR-285.

USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. Presents papers

on old-growth forests; Douglas-fir forests, diurnal forest birds, small mammals, and

amphibians of Oregon and Washington; old-growth communities in northern California and

southern Oregon; and wildlife and forest management in the Pacific Northwest.

Sillett, S.C., B. McCune, J.E. Peck, T.R. Rambo, and A. Ruchty. 2000. Dispersal limitations of

epiphytic lichens result in species dependent on old-growth forests. Ecological Applications

10(3):789–799. See abstract, page 72.

Tappeiner, J.C., D. Huffman, D. Marshall, T.A. Spies, and J.D. Bailey. 1997. Density, ages, and

growth rates in old-growth and young-growth forests in coastal Oregon. Canadian Journal of

Forest Research 27:638–648. See abstract, page 69.

Thysell, D.R., and A.B. Carey. 2000. Effects of forest management on understory and overstory

vegetation: a retrospective study. General Technical Report PNW–GTR-488. USDA Forest

Service, Pacific Northwest Research Station, Portland, Oregon. Examines plant communities

in Douglas-fir forests with divergent management histories.

Thysell, D.R., and A.B. Carey. 2001. Manipulation of density of Pseudotsuga menziesii canopies:

preliminary effects on understory vegetation. Canadian Journal of Forest Research

31(9):1513–1525. Examines effects of inducing heterogeneity in managed forest canopies on

species composition.

Wilson, E.O. 1984. Biophilia. Harvard University Press, Cambridge, Massachusetts. Focuses on

biological diversity, its endangerment, and the need for an environmental ethic.

Wilson, E.O., editor. 1988. Biodiversity. National Academy Press, Washington, D.C. Reviews

biodiversity, monitoring, restoration ecology, and preservation, based on the 1986 National

Forum on BioDiversity.

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MANAGING FOR BIODIVERSITY IN YOUNG FORESTS

Wilson, S.M., and A.B. Carey. 2000. Legacy retention versus thinning: influences on small

mammals. Northwest Science 74(2):131–145. Compares effects of management strategies on

small-mammal communities in western Washington.

Yaffee, S.L. 1994. The wisdom of the spotted owl: policy lessons for a new century. Island

Press, Washington, D.C. Reviews the spotted-owl controversy as a transition point in

biodiversity policy, thus shifting understanding from a localized species perspective to one

of larger landscapes.

Videos

Muir, P.S. 1997. Enhancing Lichens and Bryophytes in Young Forests [videocassette]. 1098 V-T.

Available from: Forestry Media Center, Oregon State University, Corvallis, Oregon.

Tappeiner, J., J. Hagar, J. Miller, E. Peterson, A. Rosso, J. Lint, P. Muir, and M. Reed. 2000.

Managing for Biodiversity in Young Forests [videocassette]. 1155 V-T. Available from:

Forestry Media Center, Oregon State University, Corvallis, Oregon.

Web Sites

Cooperative Forest Ecosystem Research. http://www.fsl.orst.edu/cfer (7 May 2002).

Epiphytes and Forest Management. http://ucs.orst.edu/~mccuneb/epiphytes.htm (7 May 2002).

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Appendix G

Selected Abstracts

Researchers involved in the Managing for Biodiversity in Young Forests Project have selected the

abstracts reprinted here as representative of current understanding of phenomena and processes

that contribute to biodiversity in each of their respective disciplines.

Vegetation

Bailey, J.D., and J.C. Tappeiner. 1998. Effects of thinning on structural development in 40-

to 100-year-old Douglas-fir stands in western Oregon. Forest Ecology and Management 108:

99–113.

We studied the composition and structure of the understory in thinned and unthinned Douglas-fir/

western hemlock stands on 32 sites in western Oregon. These stands had regenerated naturally

after timber was harvested between 1880 and 1940; they were thinned between 1969 and 1984.

Commercially thinned stands had 8–60% of their volume removed 10–24 years before the study.

Undisturbed old-growth Douglas-fir stands were present for comparison on 20 of these paired

sites. Conifer regeneration density and frequency were consistently greater in thinned than

unthinned stands. For example, average seedling density in thinned stands (1433/ha) was

significantly (p ≤ 0.001) greater than in unthinned stands (233/ha), but very similar to that in oldgrowth stands (1010/ha). Seedling density and frequency were strongly related to the volume

removed and to stand density index (and other measures of overstory density) just after thinning.

In thinned stands, the density of small trees (intermediate crown class overstory trees and

advanced regeneration) was 159/ha, significantly (p ≤ 0.001) greater than in unthinned stands (90/

ha), but not significantly different from that of old-growth (204/ha). The live crown ratio of these

trees in thinned stands (66%) was greater than in unthinned (44%) and old-growth (48%) stands.

Cover and stem density of shrubs was variable in all three stand types. There was significantly

less tall shrub cover in unthinned stands than in either thinned or old-growth stands, which did

not differ. Thinned stands had the most low shrub cover. Salal and bracken fern cover was greater

in thinned stands than in the other stand types, but there was no difference in sword fern and

Oregongrape cover. Leaf area index in thinned stands (6.6) was not significantly different from

that in unthinned (6.8) and old-growth stands (7.1); however, there was more leaf area in shrubs

in the thinned stands. Thinning young Douglas-fir stands will hasten the development of

multistory stands by recruitment of conifer regeneration in the understory as well as by enabling

the survival of small overstory trees and growth of advanced understory regeneration. Thinning

will also help develop the shrub layer by increasing tall shrub stem density and cover of some

low shrubs.

Reprinted from Forest Ecology and Management, Volume 108, J.D. Bailey and J.C. Tappeiner,

Effects of thinning on structural development in 40- to 100-year-old Douglas-fir stands in

western Oregon, Pages 99–113, 1998, with permission from Elsevier Science.

Bailey, J.D., C. Mayrsohn, P.S. Doescher, E. St. Pierre, and J.C. Tappeiner. 1998. Understory

vegetation in old and young Douglas-fir forests of western Oregon. Forest Ecology and

Management 112:289–302.

We studied understory composition in thinned and unthinned Douglas-fir (Pseudotsuga menziesii

(Mirb.) Franco)/western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands on 28 sites in western

Oregon. These stands had regenerated naturally after timber harvest, 40–70 years before thinning.

Commercial thinning had occurred 10–24 years previously, with 8–60% of the volume removed

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from below with the intent to homogenize spacing among trees. Undisturbed old-growth

Douglas-fir stands were present for comparison on 18 of these sites. Total herbaceous cover was

greater in thinned (25% cover) stands than in unthinned (13% cover) or old-growth (15% cover)

stands. Species richness was also greater in thinned (137) than in unthinned (114) and old-growth

(91) stands (P=0.05). Part of the increased richness was caused by the presence of exotic species

in thinned stands, but there were also more native grass and nitrogen-fixing species in thinned

stands than in unthinned or old-growth stands. Groups of species differed among stand-types.

For example, the frequency of tall cordate-leaved species was greater in old-growth stands

(P=0.009), but their relative cover was different only between old-growth and unthinned stands

(P=0.08). Both the cover and frequency of grasses and sedges in thinned stands were greater than

in unthinned or old-growth stands (P≤0.002). Ordination of shrub cover showed differences

among old-growth and unthinned stands compared to thinned stands, mainly because of the

amount of Gaultheria shallon Pursh and Polystichum munitum (Kaulf.) Presl in heavily thinned

stands. Ordination of herbaceous community data showed that there were much stronger

differences among sites than among stand-types. The lack of difference among stand-types

demonstrates the resiliency of herbaceous communities to disturbance associated with past and

current forest management.

Reprinted from Forest Ecology and Management, Volume 112, J.D. Bailey, C. Mayrsohn, P.S.

Doescher, E. St. Pierre, and J.C. Tappeiner, Understory vegetation in old and young Douglas-fir

forests of western Oregon, Pages 289–302, 1998, with permission from Elsevier Science.

Hayes, J.P., S.S. Chan, W.H. Emmingham, J.C. Tappeiner, L.D. Kellogg, and J.D. Bailey. 1997.

Wildlife response to thinning young forests in the Pacific Northwest. Journal of Forestry

95(8):28–33.

In western Oregon and Washington, hundreds of thousands of forested acres are in early seral

stages (0 to 50 years old). Many of these stands are structurally simple, having a single canopy

layer, limited number of tree species, relatively little understory, and in some cases, few standing

or fallen dead trees. Management objectives for these lands vary, but whether managers want to

maximize wood fiber yield or conserve biodiversity, commercial thinning may help them

achieve their goals. In this article we examine the effects of thinning on wildlife and their

habitat in forests of western Oregon and Washington, but many of the principles are applicable

to other regions.

Reprinted from Journal of Forestry, volume 95, number 8, pages 28–33, published by the Society

of American Foresters, 5400 Grosvenor Lane, Bethesda, MD 20814–2198. Not for further

reproduction.

Tappeiner, J.C., D. Huffman, D. Marshall, T.A. Spies, and J.D. Bailey. 1997. Density, ages, and

growth rates in old-growth and young-growth forests in coastal Oregon. Canadian Journal of

Forest Research 27:638–648.

We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga

menziesii (Mirb.) Franco) old-growth stands on 10 sites and compared them with young-growth

stands (50–70 years old, regenerated after timber harvest) in the Coast Range of western Oregon.

The diameters and diameter growth rates for the first 100 years of trees in the old-g[r]owth stands

were significantly greater than those in the young-growth stands. Growth rates in the old stands

were comparable with those from long-term studies of young stands in which density is about

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100–120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees

in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10

years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged

period, and trees grew at low density with little self-thinning; in contrast, after timber harvest,

young stands may develop with high density of trees with similar ages and considerable selfthinning. The results suggest that thinning may be needed in dense young stands where the

management objective is to speed development of old-growth characteristics.

Reprinted by permission of NRC Research Press.

Epiphytic Lichens and Bryophytes

Lesica, P., B. McCune, S.V. Cooper, and W.S. Hong. 1991. Differences in lichen and bryophyte

communities between old-growth and managed second-growth forests in the Swan Valley,

Montana. Canadian Journal of Botany 69:1745–1755.

Lichen and bryophyte communities differed between managed second-growth and unmanaged

old-growth grand fir forests in northwestern Montana in all three strata examined: lower canopy,

trunk, and ground. Old-growth forests had larger trees, greater structural diversity, greater

volumes of coarse woody debris, fewer species of vascular plants, more species of trunk

epiphytes, higher β diversity, and higher γ diversity than second-growth forests. Although pendent

fruticose lichens were common in both stand age classes, species of Alectoria were more

abundant in old growth, while second growth was dominated by Bryoria spp. Nitrogen-fixing

foliose lichens were more common in all strata of old growth, and Lobaria pulmonaria, a

common N-fixing species in old growth, was absent in second growth. Cladonia spp. were more

numerous in second-growth forests. Nearly all species of leafy liverworts were more common in

old growth and typically occurred on rotting wood. Many of these liverworts were absent from

second growth. Our results suggest that many species of lichens and bryophytes find optimum

habitat in old-growth forests and that these species will become less common as silvicultural

practices continue to convert old growth to younger aged forests.

Reprinted by permission of NRC Research Press.

McCune, B. 1993. Gradients in epiphyte biomass in three Pseudotsuga–Tsuga forests of different

ages in western Oregon and Washington. The Bryologist 96(3):405–411.

Epiphyte biomass on branches and trunks was estimated for 42 individual felled trees, distributed

among three Pseudotsuga menziesii–Tsuga heterophylla stands aged 95, 145, and 400+ years, in

the western Cascade Range of Oregon and Washington, then extrapolated to the whole stands by

regression techniques. Epiphytes were sorted into four groups defined by ecological roles rather

than taxonomy: cyanolichens, alectorioid lichens, other lichens, and bryophytes. In general the

spatial sequence of dominance of these four groups, from upper canopy to forest floor, was:

“other” lichens, alectorioid lichens, cyanolichens, and bryophytes. The zones of these functional

groups of epiphytes apparently migrate upward in forests through time. For example the

Hypogymnia and Platismatia that dominate throughout canopies in young forests are found

primarily in the upper canopies of old forests. Similarly, bryophytes enter a stand near the forest

floor and gradually expand their dominance upwards. Epiphyte biomass was greatest in the oldgrowth stand, with about 2.6 t/ha. In the two younger stands total epiphyte biomass was about 1 t/

ha. The old-growth stand differed from the younger stands in having over 1 t/ha of cyanolichens,

while this group was essentially absent from the younger stands. As a synthesis of these and

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previous results, a similar gradient hypothesis is proposed: epiphyte species are ordered similarly

on three distinct spatial and temporal gradients: 1) vertical differences in species composition

within a given stand, 2) species compositional differences among stands differing in moisture

regime but of the same age, and 3) changes in species composition through time in a given stand.

Reprinted by permission of the American Bryological and Lichenological Society, Inc.

Neitlich, P.N., and B. McCune. 1997. Hotspots of epiphytic lichen diversity in two young

managed forests. Conservation Biology 11(1):172–182.

Understanding within-stand variation in diversity of epiphytes will provide an improved basis for

producing timber while conserving biological diversity. Two 80-ha, 50-year-old managed stands

of conifers were surveyed to locate 0.4 ha putative “diversity” plots, the areas appearing most

diverse in lichen epiphytes. These plots were generally located in areas made heterogeneous by

canopy gaps, wolf trees (trees with large-diameter lower branches), and old-growth remnant

trees. “Matrix” plots, in contrast, were chosen at random from the remaining, more

homogen[e]ous forest. Diversity plots hosted from 25% to 40% more epiphytic lichen species

than matrix plots in both stands. The strongest within-stand gradients in species composition

were correlated with percentage of plot occupied by gaps and wolf trees. Percentage of the plot in

gaps was correlated with species richness (r = 0.79). In the more structurally diverse stand,

diversity and abundance of nitrogen-fixing “cyanolichens” were correlated with percentage of the

plot occupied by gaps (0.5 < r < 0.9), and alectorioid lichens were correlated with percentage of

the plot occupied by old-growth remnant trees (0.5 < r < 0.6). In the stand with more

homogen[e]ous structure, percentage of the plot under gaps was correlated with regionally

common species that were otherwise absent or sparse in the matrix. Protecting gaps, hardwoods,

wolf trees, and old-growth remnant trees during thinning or other partial cutting is likely to

promote the majority of epiphytic macrolichens in young conifer forests. Because these features

are easily recognized on aerial photos and on the ground by land managers, it is practical to

manage for forest structures that would promote lichen diversity.

Reprinted by permission of Blackwell Science, Inc.

Peck, J.E., and B. McCune. 1997. Remnant trees and canopy lichen communities in western

Oregon: a retrospective approach. Ecological Applications 7(4):1181–1187.

The “New Forestry” practice of green-tree retention is becoming an important management tool

for publicly owned lands, yet few data exist to demonstrate that this tool can succeed at

enhancing biodiversity. We addressed this issue by using a retrospective approach to compare

canopy lichen litter in adjacent, paired stands of rotation age (55–120 yr): one with and one

without old-growth (>300 yr) remnant trees. We sampled three functional groups of lichens in 17

stands in western Oregon: alectorioid lichens, cyanolichens, and green-algal foliose lichens.

Thirteen stands were low elevation (520–850 m) and four were mid-elevation (1220–1340 m).

Biomass of cyanolichen and green-algal foliose lichen litter was greater in low-elevation sites,

whereas alectorioid lichen litter biomass was greater in mid-elevation sites. Cyanolichens were

absent from all mid-elevation sites. Biomass of alectorioid lichen and cyanolichen litter was

greater in low-elevation sites with remnant trees than in those without remnant trees by 86% and

233%, respectively. The biomass of green-algal foliose lichen litter was 80% greater in midelevation sites without remnant trees than in those with remnant trees. Total lichen litter biomass

was slightly, but not significantly, greater in stands with remnant trees at both low elevations (by

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23%; ~370 kg/ha standing biomass in remnant stands) and mid elevations (by 12%; ~470 kg/ha

standing biomass). Cyanolichen litter biomass was positively related to the number of remnant

trees present; alectorioid and green-algal lichen litter biomass were negatively correlated with the

density of trees in the regeneration cohort. Because retaining live remnant trees will differentially

affect these three functional groups of macrolichens, managers must be clear as to their

objectives before using green-tree retention as a tool to enhance biodiversity.

Reprinted by permission of the Ecological Society of America.

Sillett, S.C., B. McCune, J.E. Peck, T.R. Rambo, and A. Ruchty. 2000. Dispersal limitations of

epiphytic lichens result in species dependent on old-growth forests. Ecological Applications

10(3):789–799.

Epiphytic lichen biomass accumulates slowly in forest canopies. We evaluated three alternative

hypotheses for the slow accumulation of epiphytic lichens, using two experiments in tree crowns

from 15 Douglas-fir forest stands representing three age classes: old growth, young, and recent

clearcuts. The first experiment evaluated whether forest age, bark roughness, or dispersal rate

limits the establishment of the dominant old-growth-associated lichen, Lobaria oregana. Surfacesterilized branches with either rough or smooth bark were repeatedly inoculated with propagules

and compared 1 yr after the last inoculation. Dispersal affected rates of establishment: inoculated

branches had 27X more newly established thalli than controls. Establishment on smooth bark was

highest in clearcuts, intermediate in young forests, and lowest in old growth. There was as much

or more establishment of sown propagules on smooth-barked branches as on rough-barked

branches in all age classes. In the second, transplant-performance experiment, Lobaria oregana

grew as rapidly in young forests as in old growth but lost biomass and suffered more injuries in

clearcuts. In contrast, L. pulmonaria performed at least as well in clearcuts as in young forests

and old growth. Poor dispersal and establishment limit the development of L. oregana

populations in Douglas-fir forests. Particular substrates and microenvironments found only in old

growth are not essential for Lobaria establishment and growth. Maximizing the number and

dispersion of remnant trees in cutting units should maximize the rate of accumulation of L.

oregana biomass in the regenerating forest. The single most important action promoting the

accumulation of old-growth-associated epiphytes will be the retention of propagule sources in

and near all cutting units.

Reprinted by permission of the Ecological Society of America.

Moths51

Hammond, P.C., and J.C. Miller. 1998. Comparison of the biodiversity of Lepidoptera within

three forested ecosystems. Annals of the Entomological Society of America 91(3):323–328.

Lepidopterans function in the dynamics of forested ecosystems by serving as defoliators,

decomposers, prey or hosts to carnivores, and pollinators. The biodiversity of Lepidoptera is thus

linked into the ecosystem by influencing nutrient cycling, plant population dynamics, and

predator-prey population dynamics. Two important measures of biodiversity are species richness

and abundance of individuals. However, values for these measures require an ecosystem context

for insightful interpretation of ecological function. We propose that such an ecosystem context is

51 These are the first studies to quantify moth species according to region and treatment. No other literature exists on this topic.

The protocol and baseline data are being established for future works. The basic need is to quantify resident moth fauna.

This quantification involves making checklists, being thorough in methods, and being capable in identification.

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gained by an assessment of host resource requirements; in the case of Lepidoptera, this means

larval host plants. The flora that contributes to the biodiversity of Lepidoptera can be grouped

into 3 major vegetation types: (1) conifers, (2) hardwood trees and shrubs, and (3) herbs and

grasses. We compared the macrolepidopteran biodiversity of 3 forested ecosystems: (1) western

Oregon, (2) eastern Oregon, and (3) West Virginia. In respective order of the above locations,

totals of 463, 385, and 475 species were found. Conifers supported 9, 10, and 1% of the species

richness. By contrast, hardwoods supported 57, 45, and 61% of the species richness, whereas

herbs and grasses supported 31, 42, and 31% of the species richness. The patterns in abundance

of individual moths were different from species richness of moths and butterflies considered

together. Comparisons of moth abundance showed conifers supported 18, 5, and 1%; hardwoods

supported 69, 39, and 77%; and herbs and grasses supported 11, 55, and 8%. Practices involved

in the management of forested ecosystems are discussed in the context of how Lepidoptera may

be used as an indicator taxon for the assessment of land management practices, and how

biodiversity of Lepidoptera could be considered in plans for habitat restoration with a specific

focus on food web relationships.

Reprinted by permission of the Annals of the Entomological Society of America.

Miller, J.C. 1990. Field assessment of the effects of a microbial pest control agent on nontarget

Lepidoptera. American Entomologist 36(2):135–139.

Species in a guild of nontarget leaf-feeding Lepidoptera on Garry oak, Quercus garryana Dougl.,

were monitored in the field for a period of 3 yr (1986–1988) to assess the ecological effects of

three applications of the microbial pest control agent, Bacillus thuringiensis Berliner var. kurstaki

within a single-season application (spring 1986). The target species for the B. thuringiensis

kurstaki application was the gypsy moth, Lymantria dispar (L.), in a large-scale eradication

program in Lane County, Oreg. Species richness in the guild of leaf-feeding Lepidoptera on

Garry oak was significantly reduced in the treated plots during all 3 yr of the study. Also, the

total number of individual nontarget Lepidoptera was significantly reduced in treated plots during

the first 2 yr but not in the third. These data suggest that certain nontarget species of Lepidoptera

may be ecologically “at risk” in large-scale pest control programs based on B. thuringiensis

kurstaki. Variables such as phenology, voltinism, and plot size are discussed regarding the

degrees of risk and type of species that may be most affected by large-scale microbial pest

control agent control and eradication programs.

Reprinted by permission of American Entomologist.

Miller, J.C. 1990(92). Effects of a microbial insecticide, Bacillus thuringiensis kurstaki, on

nontarget Lepidoptera in a spruce budworm-infested forest. Journal of Research on the

Lepidoptera 29(4):267–276.

Species in a guild of nontarget leaf-feeding Lepidoptera on tobacco brush, Ceanothus velutinus

Dougl. were monitored in the field to assess ecological effects of one application of the microbial

pest control agent, Bacillus thuringiensis Berliner var. kurstaki [BTK]. The Lepidoptera were

sampled to compare species richness, species evenness, species diversity, larval abundance, and a

dominance index between an untreated and BTK treated site over a period of two years. The

guild of leaf-feeding Lepidoptera on C. velutinus consisted of 32 species. No statistically

significant differences were observed in overall species richness, although the number of species

in the untreated site was 30% higher two weeks after treatment. However, species richness among

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uncommon species was significantly reduced in the treated site. Also, no statistically significant

differences were observed in species evenness or species diversity but the indices were lower in

the untreated site in three of the four post-treatment samples. A dominance index was

consistently higher in the untreated site. The total number of caterpillars per 100 sec sampling

was significantly higher (5.4-fold) in the untreated site in the early summer sample, two weeks

after treatment. Also, larval abundance in the early summer sample was significantly higher (3.5-

fold) one year later. No differences were noted in larval abundance in the late summer sample in

either year.

Reprinted by permission from the Journal of Research on the Lepidoptera.

Miller, J.C. 1993. Insect natural history, multi-species interactions and biodiversity in

ecosystems. Biodiversity and Conservation 2:233–241.

The composition and dynamics of ecosystems are influenced by insects serving as providers,

eliminators and facilitators across multiple trophic levels. The role of insects in ecosystems may

be documented by manipulative field studies involving exclusion techniques applied to species

that are decomposers, herbivores or predators. The presence or absence of insects is important to

the distribution, abundance and diversity of plants and vertebrates, which typically are the

premier species in conservation efforts. Thus, policy-making in environmental management

programmes should consider the role of insects in ecosystems when establishing objectives and

procedures for species conservation and biodiversity.

Reprinted from Biodiversity and Conservation, volume 2, 1993, pages 233–241, Insect natural

history, multi-species interactions and biodiversity in ecosystems, by J.C. Miller, © 1993

Chapman & Hall, with kind permission from Kluwer Academic Publishers.

Miller, J.C. 1995. Caterpillars of Pacific Northwest forests and woodlands. FHM–NC-06-95.

USDA Forest Service, National Center of Forest Health Management, Morgantown, West

Virginia.

...Identifying field-collected caterpillars to the species level is essential to performing natural

history observations and conducting detailed ecological studies on caterpillars and host plants,

parasitoids and host caterpillars, and using caterpillars as indicator species in assessing

environmental impacts. Diagnostic keys for identifying species of caterpillars in the Pacific

Northwest are not available.... This booklet is a field guide with keys to the identification of

caterpillars commonly found in forests and woodlands of the Pacific Northwest. It contains a

brief section on the natural history of caterpillars and describes variations in morphology, color,

and pattern that are used to identify caterpillars. It also provides details on how to collect and rear

caterpillars, and how to photograph and preserve specimens. Included are a section on

nomenclature and a description of the families most commonly found in the Pacific Northwest.

Miller, J.C., and P.C. Hammond. 2000. Macromoths of Northwest forests and woodlands.

FHTET–98-18. USDA Forest Health Technology Enterprise Team, Morgantown, West Virginia.

...Identifying field-collected macromoths, either adults or caterpillars, to the species level is

essential to performing natural history observations, accurately labelling collections, and

conducting detailed ecological studies on host plants, parasitoids, and using Lepidoptera as

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indicator species in assessing environmental impacts. This guide to identification of the adults of

macromoths of forests and woodlands with an emphasis on the fauna of the Pacific Northwest

serves to complement a field guide to the caterpillars of Pacific Northwest forests and woodlands

(Miller 1995). We have selected 251 species for diagnostic narratives and photographs of adults.

Also, we have included discussion on over 300 additional species in diagnosing similar species to

those featured with photographs. The geographical range for these species as a whole covers not

just the Pacific Northwest States but also west of the Rocky Mountains and from northern

California to southern British Columbia.

Birds

Chambers, C.L., W.C. McComb, and J.C. Tappeiner II. 1999. Breeding bird responses to three

silvicultural treatments in the Oregon Coast Range. Ecological Applications 9(1):171–185.

Silvicultural alternatives to clear-cutting have been suggested to promote development, retention,

or creation of late-successional features such as large trees, multilayered canopies, snags, and

logs. We assessed bird response to three silvicultural alternatives to clear-cutting that retained

structural features found in old Douglas-fir (Pseudotsuga menziesii) forests and that imitated

natural disturbance regimes more closely than did traditional clear-cutting: (1) small-patch group

selection treatment representing a low-intensity disturbance; (2) two-story treatment, representing

a moderate to high-intensity disturbance; and (3) modified clear-cut treatment, representing a

high-intensity disturbance. We counted diurnal breeding birds 1 yr prior to and 2 yr after harvest

to estimate effects of the silvicultural treatments on bird communities compared with uncut

controls. The small-patch group selection treatment was most similar in species composition to

control stands. The two-story treatment was more similar to the modified clear-cut treatment. Ten

bird species remained abundant following the small-patch group selection treatment. They

declined in abundance in modified clearcuts and two-story stands. These species included four

neotropical migratory species and five species with restricted geographic ranges and habitat

associations. Nine species increased in response to moderate and/or high-intensity disturbances.

This group included a larger proportion of species that were habitat generalists. Silvicultural

treatments imitating low-intensity disturbances were most effective in retaining bird communities

associated with mature forest; high-intensity disturbances such as the two-story and modified

clear-cut treatments greatly altered bird community composition. Bird responses to the

silvicultural treatments that we studied indicate that a variety of stand types is needed to meet

needs of all species.

Reprinted by permission of the Ecological Society of America.

Hagar, J.C., W.C. McComb, and W.H. Emmingham. 1996. Bird communities in commercially

thinned and unthinned Douglas-fir stands of western Oregon. Wildlife Society Bulletin

24(2):353–366.

We compared abundance and diversity of breeding and winter birds between commercially

thinned and unthinned 40- to 55-year-old Douglas-fir (Pseudotsuga menziesii) stands in the

Oregon Coast Ranges. Abundance of breeding birds was greater in thinned stands. Bird species

richness was correlated with habitat patchiness and densities of hardwoods, snags, and conifers.

During the breeding season, Hammond’s flycatchers (Empidonax hammondii), hairy

woodpeckers (Picoides villosus), red-breasted nuthatches (Sitta canadensis), dark-eyed juncos

(Junco hyemalis), warbling vireos (Vireo gilvus), and evening grosbeaks (Coccothraustes

vespertinus) were more abundant in thinned than unthinned stands. Pacific-slope flycatchers

75
BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR–2002-0006

(Empidonax difficilis) were more abundant in unthinned stands. Golden-crowned kinglets

(Regulus satrapa), gray jays (Perisoreus canadensis), and black-throated gray warblers

(Dendroica nigrescens) were more abundant in unthinned than thinned stands, but these patterns

were inconsistent between seasons, regions, or years. Stand-scale habitat features were associated

with the abundance of 18 bird species.

Reprinted by permission of The Wildlife Society.

76
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Standard Form 298 (rev. 2-89)

Prescribed by ANSI Std. Z39-18

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NSN 7540-01-280-5500

October 2002 Biological Science Report

Managing for Biodiversity in Young Douglas-Fir Forests of Western Oregon

Patricia S. Muir, Rosanna L. Mattingly, John C. Tappeiner II, John D. Bailey, Wayne E.

Elliott, Joan C. Hagar, Jeffrey C. Miller, Eric B. Peterson, and Edward E. Starkey

U.S. Department of the Interior, U.S. Geological Survey

USGS/BRD/BSR–

2002-0006

U.S. Department of the Interior, U.S. Geological Survey

Prepared as part of an interagency agreement between the USGS Forest and Rangeland Ecosystem Science Center

and Oregon State University under the auspices of the Cooperative Forest Ecosystem Research Program.

Release unlimited. Available from the National Technical Information Service, 5825

Port Royal Road, Springfield, Virginia 22161 (800-553-6847 or 703-487-4650).

Available to registered users from the Defense Technical Information Center, Attn.:

Help Desk, 8725 John J Kingman Road, Suite 0944, Fort Belvoir, Virginia 22060-

6218 (800-225-3842 or 703-767-9050).

To be determined

Unclassified Unclassified Unclassified Unlimited

This project addressed potential contributions of forest thinning to enhancing biodiversity and accelerating

development of old-growth characteristics in relatively young Douglas-fir forests typical of those managed

according to the Northwest Forest Plan. Studies focused primarily on 32 paired unthinned and thinned stands

and 20 associated old-growth stands in the Coast Range and Cascade mountains of western Oregon. Data were

collected on vascular plants in most stands surveyed, and on epiphytic lichens and bryophytes, moths, and

birds in subsets of these stands. Studies assessed whether or not (1) communities of organisms differed among

stand types, (2) communities in thinned stands were more similar to those in old-growth stands than were

those in unthinned stands, (3) species diversity or abundance was related to specific stand features, and (4)

these specific stand features were shared across taxa. Results indicated that communities differed among stand

types, and that communities in thinned stands were not necessarily more similar to old-growth communities

than were those in unthinned stands. Variation in stand conditions appeared to enhance biodiversity, and

hardwood trees and shrubs were important for many species. These and other results form the basis for

general thinning guidelines, which are presented here, and will guide future research.

 biodiversity, bryophytes, community analysis, epiphytes,

forest management, functional groups, hardwoods, lichens, moths, neotropical

migratory songbirds, Northwest Forest Plan, old-growth forests, remnant trees,

shrubs, thinning, variable-density thinning, vegetation

USGS Forest and Rangeland Ecosystem

Science Center, Cooperative Forest Ecosystem Research Program,

Meta Writing and Education Services, and Ecopress.

Production Staff

NOTE: The mention of trade names does not constitute endorsement or recommendation for use by the Federal Government.

Editor

Designer

Coordination

Rosanna Mattingly

Rosanna Mattingly (contents)

John Ledges (cover)

Ruth Jacobs

Janet Erickson

Betsy Littlefield
U.S. Department of the Interior

U.S. Geological Survey

As the Nation’s principal conservation agency, the Department of the Interior has responsibility for most of

our nationally owned public lands and natural resources. This responsibility includes fostering the sound use

of our lands and water resources; protecting our fish, wildlife, and biological diversity; preserving the environmental and cultural values of our national parks and historical places; and providing for the enjoyment of life

through outdoor recreation. The Department assesses our energy and mineral resources and works to ensure

that their development is in the best interests of all our people by encouraging stewardship and citizen

participation in their care. The Department also has a major responsibility for American Indian reservation

communities.