United States

Department of 

Agriculture

Forest Service

Pacific Northwest

Research Station

General Technical

Report

PNW-GTR-635

May 2005

Balancing Ecosystem Values:

Innovative Experiments for

Sustainable Forestry

Charles E. Peterson and Douglas A. Maguire, Editors
EDITORS

Charles E. Peterson is program manager, Resource Management and Productivity Program, Pacific Northwest Research

Station, Portland Forestry Sciences Laboratory, 620 SW Main St., Suite 400, Portland, OR 97205; Douglas A. Maguire 

is an associate professor, Department of Forest Science, Oregon State University, Corvallis, OR 97331.

Technical editor: Rhonda Mazza, Pacific Northwest Research Station, Portland Forestry Sciences Laboratory, 

620 SW Main St., Suite 400, Portland, OR 97205

Scientific reviewer: Toni De Santo, Pacific Northwest Research Station, Juneau Forestry Sciences Laboratory, 

2770 Sherwood Ln., Juneau, AK 99801

Graphic designer: Jenny Beranek, Beaverton, OR 97006

Cover graphic by Sandra Arbogast, College of Forestry, Oregon State University Corvallis, OR 97331

Papers were provided by the authors in camera-ready form for printing. Authors are responsible for the content and accuracy. Opinions expressed 

may not necessarily reflect the position of the U.S. Department of Agriculture. 

The use of trade or firm names is for information only and does not imply endorsement by the U.S. Department of Agriculture of any product or service.
Balancing Ecosystem Values:

Innovative Experiments for

Sustainable Forestry

Charles E. Peterson 

and Douglas A. Maguire, Editors

August 15-20, 2004

Portland, Oregon

U.S. Department of Agriculture

Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report

PNW-GTR-635

May 2005
This page was intentionally left blank.
ABSTRACT

Peterson, Charles E.; Maguire, Douglas A., eds. 2005. Balancing ecosystem values: innovative experiments for 

sustainable forestry: Proceedings of a conference. Gen. Tech. Rep. PNW-GTR-635. Portland, OR: U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Research Station. 389 p. 

Balancing Ecosystem Values: Innovative Experiments for Sustainable Forestry is a compendium of more than 40 contributions from Asia, Europe, and North America. The theme encompasses experiments implemented at an operational scale

to test ecological, social, or economic responses to silvicultural treatments designed to balance the complex set of objectives 

currently targeted in sustainable forest management. Several invited and plenary papers emphasize the variety of outcomes

demanded by the public, as well as the essential role that these long-term studies will play in allowing natural resource

managers to make better-informed, science-based decisions. A broad spectrum of silvicultural treatments and systems are

covered, as are simulation runs with different types of models and discussion about design challenges for scaling up from

stands to landscapes. Diverse forest ecosystems, stand structures and plant, animal, and fungal species are also considered.

The conference included 2 days in the field where participants saw several types of the comprehensive field experiments

firsthand. The conference concluded with a critique from state, private, and public land managers.

KEYWORDS: Sustainable forestry, biodiversity, variable retention, public acceptance, adaptive management, silvicultural

options, landscape-level effects.
PLANNING COMMITTEE

Charles E. Peterson, USDA Forest Service

Jerry F. Franklin, University of Washington

James W. Golden, USDA Forest Service

Douglas A. Maguire, Oregon State University

Robert Szaro, USDA Forest Service

John Innes, Forest Sciences Centre

David Lindenmayer, The Australian National University

Steve Reutebuch, USDA Forest Service

Klaus von Gadow, University of Goettingen

ORGANIZING COMMITTEE

Charles E. Peterson, USDA Forest Service

Douglas A. Maguire, Oregon State University

Rick Abbott, USDA Forest Service

David Marshall, USDA Forest Service

SCIENTIFIC OVERSIGHT COMMITTEE

Charles E. Peterson, USDA Forest Service

Keith Aubrey, USDA Forest Service

Paul Anderson, USDA Forest Service

Douglas A. Maguire, Oregon State University

SPONSORS

International Union for Forest Research Organizations

Pacific Northwest Research Station, USDA Forest Service

Oregon State University

University of Washington

University of British Columbia

Biometrics Working Group, Society of American Foresters

Silviculture Working Group, Society of American Foresters

Forest Ecology Working Group, Society of American Foresters

Swiss Federal Institute for Forest, Snow and Landscape Research

OREGON STATE UNIVERSITY FORESTRY

OUTREACH EDUCATION OFFICE

Joe Holmberg

Nathalie Gitt

Cindy Wardles
Balancing Ecosystem Values Proceedings

CONTENTS

FOREWORD 

ACKNOWLEDGMENTS

KEYNOTE PAPERS

Adaptive Management for Biodiversity in Managed Forests – It Can Be Done 3

Fred L. Bunnell 

Long-Term Studies: The Basis for Science-Based Resource Management 13

Jerry Franklin

Forest Management: Science-Based and Understandable 15

Klaus von Gadow and Christoph Kleinn

Long-Term Forest Experiments: The Need to Convert Data Into Knowledge 25

John L. Innes

REGIONAL EXPERIMENTS 

Invited Papers

Design Challenges in Large-Scale Management Experiments 35

Lisa M. Ganio and Klaus J. Puettmann

Integrating Natural Disturbance Parameters into Conventional Silvicultural Systems: Experience 

From the Acadian Forest of Northeastern North America 41

Robert S. Seymour

Do Innovative Experiments Lead to Innovative Silvicultural Systems? 49

Klaus J. Puettmann

Voluntary Papers

Variable-Retention Adaptive Management Experiments: Testing New Approaches for Managing 

British Columbia’s Coastal Forests 55

William J. Beese, B. Glen Dunsworth, and Nick J. Smith

Development of Stand Structure in Young Douglas-fir Plantations 65

Carrie A. Berger and Klaus J. Puettmann

Blending Stand-Level Treatments and Landscape Planning with Opportunities for Research 

in a Working Forest 69

Jeff A. Boyce

Public Perceptions of Alternative Silvicultural Treatments 75

Gordon A. Bradley

Integrated, Interdisciplinary Forest Research at Solling, Germany—History and Perspectives 79

Michael Bredemeier, Claus Döring, and Martin Jansen

Silviculture Treatments for Ecosystem Management in the Sayward – The STEMS Experiment 89

Louise de Montigny

Tree and Understory Responses to Variable-Density Thinning in Western Washington 97

Constance A. Harrington, Scott D. Roberts, Leslie C. Brodie
Managing for Old-Growth Structure in Northern Hardwood Forests 107

William S. Keeton

Evaluation of Silvicultural Options for Harvesting Douglas-fir Young-Growth Production Forests 119

David D. Marshall and Robert O. Curtis 

Maintaining Old-Growth Features in Forests Used for Wood Production in Southeast Alaska 127

Michael H. McClellan and Paul E. Hennon

Montane Alternative Silvicultural Systems (MASS): Designing Experiments for the Future (abstract) 135

Alan K. Mitchell and William J. Beese

Comparing Changes in Scenic Beauty Produced by Green-Tree Retention Harvests, Thinnings 

and Clearcuts: Evidence From Three Pacific Northwest Experiment 137

Robert G. Ribe

Ten-Year Results of the Forest Ecosystem Research Program – Successes and Challenges 147

Mike R. Saunders and Robert G. Wagner

Seeking Alternatives to Clearcutting in British Columbia: The Role of Large-Scale Experiments 

for Sustainable Forestry 155

Alan Vyse, Alan K. Mitchell, and Louise de Montigny

Are Landscape-Level Effects More than the Sum of Stand-Level Effects in the Missouri Ozark 

Forest Ecosystem Project? 165

Eric K. Zenner, John M. Kabrick, Jennifer K. Grabner, and Randy G. Jensen

MODELING AND SIMULATION

Invited Papers

Application of Simulation Models to the Design and Analysis of Silvicultural Systems in 

British Columbia 175

James W. Goudie, C. Mario Di Lucca, Walt Klenner, Ian R. Cameron, Roberta Parish, 

Kenneth R. Polsson

Scaling Up From Stands to Landscapes 187

Thomas A. Spies

Voluntary Papers

Simulating Structural Development and Fire Resistance of Second-Growth Ponderosa Pine Stands 

for Two Contrasting Stand Treatments 191

Stephen Fitzgerald, Douglas A. Maguire, and Ryan Singleton

Predicting the Cumulative Effects of Forest Management in a Multi-Ownership Forest Landscape (abstract) 199

David Lytle

Projections of Future Overstory Stand Structure and Composition Following Variable-Retention 

Harvests in the Northwestern United States 201

Paul Schwarz, Douglas A. Maguire, and Doug Mainwaring

Effects of Different Levels of Canopy Tree Retention on Stocking and Yield of the Regeneration 

Cohort in the Southern Interior of British Columbia 215

Hailemariam Temesgen, Pat J. Martin, Douglas A. Maguire, and John C. Tappeiner
BIODIVERSITY

Invited Papers

Active Intentional Management (AIM) for Biodiversity and Other Forest Values 227

Andrew B. Carey

Voluntary Papers

The Effect of Forested Corridors Within Harvested Pine Plantations on Herpetofauna Assemblages 235

William M. Baughman and David C. Guynn, Jr.

Vegetation Response to Alternative Thinning Treatments in Young Douglas-fir Stands 243

Liane R. Beggs, Klaus J. Puettmann, and Gabriel F. Tucker

Observed Changes in Ground Saturation, Aquatic Invertebrate Densities, and Breeding Bird 

Populations Following Various Harvesting Intensities 249

Adelaide C. Johnson, Jacob Musslewhite, Toni L. De Santo, and Rick T. Edwards

Results From Green-Tree Retention Experiments: Ectomycorrhizal Fungi 257

Daniel L. Luoma and Joyce Eberhart

Green-Tree Retention in Managed Forests: Post-Harvest Responses of Salamanders 265

Chris C. Maguire, Tom Manning, Stephen D. West, and Robert A. Gitzen

Fate of Taxa After Variable-Retention Harvesting in Douglas-fir Forests of the Northwestern 

United States 271

Douglas A. Maguire, Sean Canavan, Charles B. Halpern, and Keith B. Aubry

Effects of Forest Structural Retention Harvest on Resource Availability and Habitat Utilization 

of Bark-Foraging Birds (abstract) 281

Maria Mayrhofer, David Manuwal, and Juraj Halaj

Using Spatially Variable Overstory Retention to Restore Structural and Compositional Complexity 

in Pine Ecosystems 285

Brian J. Palik, Christel C. Kern, Robert Mitchell, and Stephen Pecot

Wildlife Response to Fire and Thinning Treatments in Ponderosa Pine (abstract) 291

Steve Zack, Kerry Farris, and Luke George

FIRE AND FIRE SURROGATES

Voluntary Papers

Restorative Management of Boreal Forest Stands With and Without Fire: An Experimental 

Approach (abstract) 295

Timo Kuuluvainen, Saara Lilja, and Ilkka Vanha-Majamaa

Effects of Thinning and Prescribed Fire on Understory Vegetation in Interior Pine Forests of California 297

Martin W. Ritchie

A Collaborative Approach to Forest Management: Using a Landscape-Level Dynamic Simulation

Model as a Tool to Enhance Communication Among Diverse Landowners 309

Christine M. Stalling

Implementation of the Fire and Fire Surrogate Study—A National Research Effort to Evaluate 

the Consequences of Fuel Reduction Treatments 315

Andrew Youngblood, Kerry L. Metlen, Eric E. Knapp, Kenneth W. Outcalt, 

Scott L. Stephens, Thomas A. Waldrop, and Daniel Yaussy
CLOSING PERSPECTIVES

Invited Papers

Balancing Ecosystem Values: A Manager’s Perspective 325

Lynn Burditt

Where Can We Go From Here? 327

E. David Ford

Summary of “Realities in Timber Management” Discussion at 2004 IUFRO Workshop 331

Russ McKinley

A Public Land Manager's Perspective: The Need for Innovative Experiments for Sustainable Forestry 335

Gretchen Nicholas

POSTER ABSTRACTS

The H.J. Andrews Uneven-Aged Management Project: Alternative Silvicultural Approaches 

to Stand Conversion 341

Paul Anderson and Jim Mayo

Variable Retention Implementation Monitoring 342

William J. Beese, Ken Zielke, and Bryce Bancroft

Characterizing Vegetation Response to Variable Density Thinnings in Young Douglas-fir 

Forests of Western Oregon 343

Shanti Berryman, Bob Fahey, and Klaus Puettmann

Black Spruce Regeneration in the Presence of Kalmia Angustifolia L; Interactions with 

Irradiance and Nutrients 344

Felix Boulanger, Bill Shipley, and Robert Bradley

Twenty-Five-Year Results of a Restoration Thinning, Redwood National Park 345

Andrew Chittick and Christopher Keyes

Density Management Study: Developing Late-Successional Habitat 347

John Cissel, Deanna Olson, Sam Chan, Klaus Puettmann, Andrew Moldenke, 

John Tappeiner, and Charley Thompson

Predicting Understory Light Availability Based on Neighborhood Height Data Derived 

from Vertical Point Sampling in Mature Douglas-fir Forests in the Western Cascades 348

Nathan Davis and Douglas Maguire

An Application of Hierarchy Theory to Long-Term Sustainability 349

Thomas Dean, Andrew Scott, and Ray Newbold

Design Issues for Small Mammal Studies in Silvicultural Experiments 351

Robert Gitzen, Stephen West, Chris Maguire, and Tom Manning

Potential of Green-Tree Retention as a Tool to Maintain Soil Function After Harvest 353

Susan Grayston, Janet Addison, Shannon Berch, Louise deMontigny, Daniel Dural, Keith Egger,

Melanie Jones, Jeffrey Lemieux, Robin Modesto, William Mohn, Tochi Panesar, Cindy Prescott, 

Suzanne Simard, and Diane Srivastava

Effects of Green-Tree Retention on the Availability of Arthropod Prey to Bark-Gleaning Birds 356

Juraj Halaj, Maria Mayrhofer, and David Manuwal
Vegetation Responses to Varying Levels and Patterns of Overstory Retention: Early Results 

of the DEMO Experiment 357

Charles Halpern, Donald McKenzi, Shelley Evans, James Saracco, Doug Maguire, and Juraj Halaj

Biodiversity at the Sicamous Creek Silvicultural Systems Project: Treatment, Edge and Site 

Preparation Effects in Subalpine Forest 360

David Huggard, Alan Vyse, Walt Klenner, and Dennis Lloyd 

Operational Comparisons and Experiments for Monitoring Habitat Structures in Weyerhaeuser’s 

Coastal BC Variable Retention 361

David Huggard, Glen Dunsworth, and Jeff Sandford 

Rediscovering What Works: The Stoddard-Neel Approach as a Case Study of 

Conservation-Oriented Sustainable Forestry 362

Steven Jack and Kevin McIntyre 

Extended Rotation Red Pine Stands in Minnesota 363

Christel Kern and Brian Palik

Demonstrating Conservation Forestry: Increasing Exposure to Increase Acceptance in the Southeast 364

Kevin McIntyre and Steve Jack

Contribution of Monitoring Research to Forest Certification and Ecologically Sustainable 

Forest Management in the Yamanashi Prefectural Forest, Central Japan 365

Takuo Nagaike 

Short-Term Responses of Vascular Plants and Bryophytes in Forest Patches Retained During 

Structural Retention Harvests 366

Cara Nelson and Charles Halpern 

Effects of Four Riparian Buffer Treatments and Thinning on Microclimate and Amphibians 

in Western Oregon Headwater Forests 369

Deanna Olson and Samuel Chan

Aesthetic Perceptions of Green-Tree Retention Harvests in Vista Views: The Interaction of Cut 

Level, Retention Pattern and Harvest Shape 370

Robert Ribe and Tony Silvaggio

Restoration of a Forested Coastal Watershed: Ellsworth Creek, Washington 371

David Rolph, Steven Rentmeester, and Jesse Langdon

Using Ethics to Educate Consumers of Natural Resources 374

Viviane Simon-Brown 

Assessment of Threats to the Conservation of Siskiyou Mountains Salamanders in Oregon 375

Nobuya Suzuki and Deanna Olson

Chronosequencial Changes in Forest Stand Structure and Composition—Comparison Between 

the Post-Harvest Secondary Deciduous Broadleaf Forests and the Plantation Forests of Evergreen

Japanese Cedar (Cryptomeria japonica) 376

Hiroshi Tanaka, Kaoru Niiyama, Mitsue Shibata, Tsutomu Yagihashi, Hanae Niwa, 

Hiroshi Yabe, Atsuko Hayashi, and Takuo Nagaike

Influence of Silvicultural Intensity and Compositional Objectives on the Productivity 

of Regenerating Acadian Forest Stands in Maine 378

Robert Wagner, Mike Saunders, Keith Kanoti, John Brisette and Richard Dionne 
Leave Islands as Refugia for Low-Mobility Species in Managed Forests 379

Stephanie Wessell, Richard Schmitz, and Deanna Olson 

Effects of Partial Logging on Community Parameters in a Northern Japanese Mixed Forest 380

Toshiya Yoshida and Mahoko Noguchi

PARTICIPANT LIST 383

UNIT CONVERSION TABLE 390
FOREWORD

Various forest management objectives have changed dramatically in recent years for lands under federal and state

ownership, and many of the traditional objectives have expanded in scope and complexity. Past silvicultural studies

tested the ability of specific treatments and systems to regenerate forests of desired composition and structure to meet

society’s needs, with primary emphasis on wood production. Wood production remains a primary economic objective

for many private and nonindustrial landowners, but on federally managed forests and rangelands, changing societal 

values now demand ever more comprehensive approaches to forest management that integrate social, ecological, and

economic goals. As a result, many recent (past decade) silvicultural experiments have become multidisciplinary in

scope and include restorative objectives, novel and untested silvicultural treatments, or traditional approaches 

expanded to operational scales.

Current silvicultural or manipulative forest ecological experiments need to address a variety of responses to changes

in forest structure and composition imposed by treatments. Meeting diverse public interests necessitates experiments

designed by interdisciplinary teams (e.g., forest ecologists, sociologists, biologists, economists, and silviculturists)

where ecological, social and economic objectives are attained as joint outcomes, in addition to wood production.

Individually and collectively these studies represent major investments by research and federal and state land management organizations to find practical solutions that meet public demands. In addition to clean air and water, people

want healthy and appealing forest environments for recreation and leisure, wildlife habitat, biological diversity characteristic of late-successional stands, and an output of wood or other forest product that supports local economies.

Solutions based on silvicultural experiments implemented at an operational scale, and that track a variety of responses,

enhance the public’s confidence in the ability of land managers to successfully achieve the desired mix of objectives. 

These proceedings present numerous examples of operational-scale experiments from North America, Europe, and

Asia; many of these experiments are in the early stages of implementation and thus unknown to many in the professions of forestry and applied ecology. In addition to presented research and poster sessions indoors, this conference

included 2 extraordinary days in the field. On the first day, participants toured the Washington State Capitol Forest to

view options for young-growth management. On the second day, participants had the option to visit several sites of a

density management study on land managed by the Bureau of Land Management in western Oregon, or tour replications of the Demonstration of Ecosystem Management Options study on the Gifford Pinchot National Forest. Quality

presentations held on site fostered rich discussions among participants. Unfortunately, space did not allow for inclusion

of field abstracts and handouts in these proceedings. 

This conference represents the second phase of a more comprehensive effort by U.S. Forest Service Research and

the International Union of Forest Research Organizations (IUFRO) to highlight these newer, long-term, operational

experiments. It follows a smaller IUFRO workshop, Applied Forest Ecological Experiments, held August 5-7, 2003 in

Davos, Switzerland. The culmination of this effort will be a special session of the 2005 IUFRO Congress in Brisbane,

Australia, entitled “Long-Term, Multi-Purpose Experiments in the Forest Sector.” 

Charles E. Peterson and Douglas A. Maguire, 

Editors
ACKNOWLEDGMENTS

There are several key people we need to acknowledge in this effort. We greatly appreciate the work of Nathalie Gitt and

Joe Holmberg at Oregon State University for the initial webpage design, the logo and cover design, compiling the pre-conference handouts, and helping with the technical needs of all the presentations. John Cissel (Bureau of Land Management),

Jon Nakae (Gifford Pinchot National Forest), and David Marshall (PNW Research Station) all did a tremendous job organizing the field tours, including the safety precautions.

Jon Nakae (Gifford Pinchot National Forest), Dan Luoma (Oregon State University), and Charley Peterson (Pacific Northwest Research Station) present

findings from DEMO on mycological diversity and green-tree retention harvests. Photo by Cara Nelson
KEYNOTE PAPERS

Fred Bunnell Jerry Franklin Klaus von Gadow John Innes
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1 Honorary Professor, Centre for Applied Conservation Research, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC V67-1Z4, Canada.

Email: fred.bunnell@ubc.ca 

Balancing Ecosystem Values Proceedings, Keynote Papers

Adaptive Management for Biodiversity 

in Managed Forests – It Can Be Done

Fred L. Bunnell1

INTRODUCTION

There are few more encompassing words than “biodiversity.” Few undertakings are more complex than forestry.

The complexity of sustaining biodiversity in managed forests

fits it well to the promise of adaptive management. Adaptive

management is a formal process for continually improving

management practices by learning from the outcomes of

operational and experimental approaches. There are, however, few success stories for adaptive management in

forestry. It is too early to pronounce this case study a success or a failure. Over its course, there have been corrective

nudges to modify practices. I first review the problem and

the ecological and social setting, then describe the four

major steps of adaptive management and how they were

enacted in coastal British Columbia (BC). 

ABSTRACT

Sustaining biological diversity and sustaining fiber production are competing objectives. Objectives for biological diversity are ill-defined and appropriate practices are little understood, but practitioners are compelled to act. The latter two features make the task suitable for adaptive management, provided it is not too complex, too costly, or too lengthy. This case

study, over 1.1 million ha in coastal temperate rainforest of British Columbia, shows that it can be done. This paper describes

what was done for each of the four main steps in an adaptive management program. Step 1, creating clear objectives,

exploited the criteria and indicator approach yielding an operational definition of biodiversity and three broad indicators

(ecosystem representation, habitat, organisms). Step 2, planning and practices to attain objectives, introduced stewardship

zoning into strategic planning and applied retention systems over the entire tenure. Step 3, creating a monitoring system to

assess proximity to objectives, is the most intellectually challenging due to the complexity of biodiversity, but can be summarized within a cross-design. The final step, feedback to management, is where we most often fail. Ways of reducing the

likelihood of failure and examples of feedback to management practices are described. These latter activities close the 

adaptive management loop.

KEYWORDS: Adaptive management, biodiversity, forest management.

3

THE PROBLEM 

Forestry has addressed multiple values for centuries.

Incorporating biological diversity as a product of forests

was a departure from other values in several ways. Foremost

was the lack of an operational definition for biodiversity.

Within 6 years of the Convention on Biological Diversity,

more than 100 competing definitions had been published.

Moreover, existing agreement promised only confusion –

all species were considered part of biological diversity, but

we did not know what all those species were or how they

would respond to forest practices. We did know that whatever we did to a forest, including nothing, favored some

species and disadvantaged others. Theory and experience

were disconnected from practice as never before (Bunnell

and Chan-McLeod 1998).
Foresters accepted responsibility for sustaining two competing values – wood products and biodiversity. Properly

managed wood products are renewable and their production

can be sustained indefinitely. Moreover, they have a much

smaller “ecological footprint” than substitute products

(Lawson 1996). Managing to create renewable products

with a small ecological footprint was a good thing. Even if

we could not define biodiversity well enough to be confident

that it was a good thing to sustain, we often were charged

to do so. Efforts to sustain a few elements of biodiversity

(e.g., spotted owl (Strix occidentalis caurina); and marbled

murrelet (Brachyrhamphus marmoratus Gmelin)) revealed

that trying to sustain all elements would create competition

between two desired products.

Exacerbating the issue is the fact that sustaining biodiversity in forested systems confronts special difficulties;

for example, more species reside within forests than in

other plant communities, we modify forests to extract 

products, and forestry must be planned over large areas and

long periods. See Bunnell and Chan-McLeod (1998) and

Bunnell et al. (1999) for a fuller treatment. 

A succinct statement of the problem is, “How can we

sustain biological diversity in managed forests?” The problem will not go away, nor will most difficulties diminish.

The largest features of the problem – little clarity about

appropriate practice, need to act despite clarity – appear

well suited for adaptive management, though complexity 

is an obvious challenge. Opportunity arose to cast the problem in an adaptive management framework in coastal

British Columbia. Before describing how adaptive management was applied, I describe the coastal setting. 

THE SETTING

Physical Landscape

The area under forest management extends over 1.1

million ha of separate pieces along the coast of British

Columbia—Vancouver Island, Gulf Islands, Queen Charlotte

Islands and mainland coast. Watercourses of various sizes

and gradient are abundant. Much of the terrain is rugged

and mountainous. Valleys usually are deep, glaciated troughs,

with gentle slopes restricted to valley floors. Ridge tops

defining valleys commonly rise over 1000 m with peaks

considerably higher. Gently sloping uplands are uncommon,

and valley sides often are steeper than 30° or 60 percent.

On gentle slopes and in the coastal lowlands, glacial and

post-glacial deposits generally bury bedrock. On steeper

slopes, weathered till is susceptible to debris slides and debris

flows. Most relief is perpendicular to prevailing weather

systems, so annual precipitation differs greatly from

windward to leeward sides. Windward areas are among the

wettest temperate regions of the world. Measurable precipitation usually occurs 200 or more days of the year, and

annual totals in most of the region range from about 175 to

440 cm. Throughout the year, the ocean modifies temperatures, so that winters are relatively mild and summers are

relatively cool (except in the driest portions).

Ecological Setting

The climate of the region encourages a landscape dominated by coniferous trees. Strong topographic influences 

on climate yield three distinct forest types (biogeoclimatic

zones of Meidinger and Pojar 1991). The coastal Douglasfir (CDF) zone occurs on the southern, rainshadow portion

of the tenure. It represents about 1 percent of the tenure,

and is present primarily on private land. The most common

tree species is Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco). Western redcedar (Thuja plicata Donn ex D.

Don), grand fir (Abies grandis (Dougl. ex D. Don) Lindl.),

arbutus (Arbutus menziesii Pursh) and red alder (Alnus

rubra Bongard) are frequently present. This zone receives

about 65 to 125 cm of precipitation annually, about 5 percent as snow. The coastal western hemlock (CWH) zone

occurs throughout the tenure outside of the rainshadow,

representing about 87 percent of the tenure. The most common tree species usually is western hemlock (Tsuga heterophylla (Raf.) Sarg.), though western redcedar is common.

Douglas-fir is naturally restricted to drier southern and

southwestern slopes. The zone receives more rain than any

other zone in the province, typically 100 to 440 cm of precipitation (more in some areas), with snowfall contributing

about 15 percent in the south and 40 to 50 percent in the

north. The CWH is broadly equivalent to coastal temperate

rainforest and hosts some of the largest, longest-lived trees

in North America. The mountain hemlock (MH) zone represents about 12 percent of the tenure and occurs above the

CWH, about 900 to 1800 m in the south and 400 to 1000

m in the north. Alpine tundra may exist above it. The most

common tree species are mountain hemlock (Tsuga mertensiana (Bongard) Carriere), amabilis fir (Abies amabilis

(Dougl. ex Loud.) Dougl. ex J.Forbes) and yellow-cedar

(Chamaecyparis nootkatensis (D.Don) Spach). The zone

receives more total precipitation than the CWH (about 170

to 500 cm annually), but 20 to 70 percent falls as snow.

These are not productive forest sites, and tree growth

becomes progressively poorer with increasing elevation,

cooler temperatures and increasing duration of snow cover. 

The area is biologically rich, but the numbers of species

present are well quantified only for vertebrates. Streams

and lakes host about 26 species of fish, 13 of which are

anadromous. Although more species are present within the

4
area, about 180 terrestrial vertebrates use forests for breeding or as important wintering habitat. 

Social and Historical Context

About 75 percent of the management area is public land,

where public concerns must be addressed far more rapidly

and directly than on private land. Much of the region is

coastal temperate rainforest, which may be the most controversial forest type in temperate regions. Logging natural

rainforest has attracted effective environmental campaigns,

including boycotts of some forest products (e.g., spotted

owl and Clayoquot Sound campaigns). 

Because it was the largest company working in coastal

rainforest, MacMillan Bloedel (since acquired by Weyerhaeuser) had long been the center of environmental campaigns in British Columbia. These were costly to the forest

industry and tended to overshadow efforts to improve practice. In 1997, the company acquired a new chief executive

officer (CEO) who wished to explore how the company

could move from controversy, and perhaps increase market

share, while still harvesting coastal rainforest. Among his

first undertakings was to form a team of researchers and

practitioners to address the question: Could MacMillan

Bloedel stop clearcutting and still regenerate the forest and

make a profit? The team collated and analyzed relevant

data to determine that it would cost more, but probably

could be done effectively. The CEO and Board of Directors

concluded the additional cost would be offset by regaining

market share and increasing shareholder value. In 1998,

MacMillan Bloedel announced it would no longer clearcut

coastal forests in British Columbia. To sustain the entire

mix of desired values, the company chose to implement

variable retention instead of clearcutting and to distribute

the variable retention approaches within stewardship zones

(which allocate different intensities of harvest). 

Although well reasoned (Beese and Zielke 1998,

Bunnell et al. 1998), the approach had never been attempted

before. MacMillan Bloedel met the challenge of assessing

consequences of their new approach by creating The Forest

Project. Primary objectives of The Forest Project were to

make variable retention operational and create an effective

approach to adaptive management. When Weyerhaeuser

acquired MacMillan Bloedel in 1999, it embraced those

objectives. Sections below describe how this approach 

to adaptive management was applied.

THE APPROACH

An adaptive management program can be separated into

four parts: (1) clearly defined objectives, (2) planning and

practices to attain objectives, (3) ways to assess proximity

to objectives, and (4) ways to modify practices if objectives

are not attained (links to management action). These are

described separately below.

Clearly Defined Objectives

We have found it helpful to employ criteria and indicators to guide management. Criteria represent success in

achieving desired outcomes within the management plan;

indicators represent measures of that success or failure.

One challenge was to create an operational definition of

biological diversity that would reflect success.

The criterion for success should reflect both scientific

and social reasons for sustaining biodiversity. A fundamental scientific reason for sustaining biodiversity is to sustain

genetic variability. However, there are no easily definable

targets for requisite genetic variability. Moreover, the only

self-replicating packages of genetic variability are species

and subspecies. These thus represent a measurable, credible,

scientific surrogate for the cluster of concepts represented

by the term “biological diversity” (Bunnell 1998, Namkoong

1998). Documents originating in the United Nations Conference on Environment and Development 1992 reveal four

major public concerns: rates of extinction, future options,

productive ecosystems and economic opportunities (Bunnell

1997). Sustaining native species richness connects directly

to these concerns. The genetically-based differences among

organisms and taxa permit continued adaptability and continued creation of biological diversity (Frankel and Soulé

1981, Mayr 1997). Retaining a variety of individuals and

species permits the adaptability that sustains ecosystem

productivity in changing environments (Naeem et al. 1994,

Tilman and Downing 1994) and also begets further diversity (future adaptability and options), thereby potentially

sustaining desirable economic opportunities. Because

species represent self-replicating packages of genetic variability and public concerns, we chose native species richness as our criterion of success.

Criterion: Biological diversity (native species richness

and its associated values) are sustained within Weyerhaeuser

BC coastal tenure.

Indicators beyond species richness are needed to encompass the content of biological diversity and to connect

directly with forest planning and practice. We chose three

indicators to encompass that content. 

Indicator 1: Ecosystems. Ecologically distinct ecosystem types are represented in the nonharvestable land base

of Weyerhaeuser’s coastal tenure to maintain lesser known

species and ecological functions. 

5
Indicator 2: Habitat. The amount, distribution, and heterogeneity of stand and forest structures important to sustain native species richness are maintained over time. 

Indicator 3: Organisms. The abundance, distribution,

and reproductive success of native species are not substantially reduced by forest practices. 

Each indicator assesses different aspects of success in

attaining the criterion. 

• Indicator 1 assesses ecosystem representation within

areas that will not be harvested and is intended primarily

to ensure that little known species and functions that may

not be assessed by Indicators 2 and 3 are sustained. It

also serves to identify unmanaged “benchmarks.” 

• Indicator 2 complements Indicator 1 by evaluating habitat

elements and structures we know are required by many

species and projecting consequences of changes in those

habitat features through time.

• Indicator 3 assesses whether species naturally present on

Weyerhaeuser’s coastal tenure are likely to continue as

well-distributed, productive populations. It serves as a

test of the broader approaches of Indicators 1 and 2.

The indicators and associated measurements encompass

much of the complexity inherent in the criterion and necessarily interact. For example, the distribution of ecologically

distinct habitat types within the nonharvestable land base

of the tenure determines the kinds of habitat provision

required in harvestable areas to meet success. Progress

assessing major indicators must proceed in parallel because

findings for each indicator inform the others. The rationale

and measurements for the indicators are discussed by

Bunnell et al. (2003). 

Planning and Practices to Attain the Objectives

Planning and practices both help sustain biological diversity. Planning removes some areas from active practice (e.g.,

riparian reserves) and provides context or a roadmap for

future stand-level practices. Practices determine local habitat

structure. Each is informed by the other. If sufficient structure is retained to maintain species at local levels, structure

need not be addressed in broad scale planning. Adaptive

management helps provide corrections to the roadmap.

Weyerhaeuser introduced stewardship zones to separate

competing objectives to the extent possible. The zoning

concentrated commercial harvesting activities, minimized

roads, and stabilized economic returns. As well, zoning

designated areas with little harvest where organisms adapted

to late-seral conditions can remain productive. The company designated three stewardship zones with different

intensities of harvest (table 1). 

The proportion of land initially allocated to each zone

was arbitrary and considered subject to change dependent

on feedback from monitoring. The three zones have different goals for both stand- and landscape-level retention of

trees to meet their different management emphases (table

1). Full descriptions of the zones are found in Beese et al.

(2003); I summarize.

The timber zone is the most extensive and the primary

source of economic values. Its primary goal is commercial

timber production. Within the zone, up to 80 percent of the

productive forest area is available for harvest throughout

the harvest cycle. The silviculture system is predominantly

even-aged management with retention ranging upward from

minimums of table 1. Some sites may receive shelterwood,

but all treatments include some permanent retention of

6

Table 1—Description of stewardship zonesa

Zone

Timber Habitat Old growth

Management emphasis Timber Habitat Late-seral forest 

production conservation conditions

Portion of managed land base in each zone 65% 25% 10%

Average proportion of productive forest area 28% 40% 70%

in reserves

Minimum long-term retention in each cutblock Dispersed: 5% Dispersed or Dispersed or

group: 10% group: 15% group: 20%

Primary silvicultural systems Retention, Retention, Selection, 

shelterwood shelterwood, irregular, 

selection shelterwood

aAdapted from Beese et al. (2003).
structural attributes. Because of its large extent and uncertainty about the outcomes from variable retention, most

monitoring occurs in this zone. The name “habitat zone”

reflects the opportunity to designate specific practices (e.g.,

retention type and level) to meet needs of specific species

in specific places. Refinements to practice can be implemented as guided by results of monitoring. A full range of

silvicultural systems with retention is anticipated in the

habitat zone. The old-growth zone is intended to maintain

late-seral forest conditions, so relatively little wood is

removed. It comprises about 10 percent of the tenure.

Within this zone, two-thirds of the forest area is reserved

from harvest, and harvest in the remainder is by uneven-aged

systems (e.g., group selection or irregular shelterwood with

retention). The old-growth zone adds to other unharvestable areas thereby sustaining poorly known ecological

functions and meeting the needs of late-successional organisms, particularly those requiring larger areas of older seral

stages. Such species may decline significantly or even

disappear from the timber zone. 

Aggregating the most conflicting values into separate

zones reduced local conflict, but was believed insufficient

to maintain all forest-dwelling organisms. To retain the

kinds of habitat required by many forest-dwelling organisms, the company also implemented variable retention

(VR) in all zones (table 1). Variable retention was adopted

because it preserves, in managed stands, far more of the

characteristics of the natural forest that many of the public

strongly value and to which organisms in the area are

adapted. Variable retention was first defined and proposed

by the Clayoquot Scientific Panel for application in the

Clayoquot Sound region of the tenure, and has since been

refined by others (e.g., see Franklin et al. 1997 and Mitchell

and Beese 2002). The company adopted the terminology to

refer to any silvicultural system that ensures that structural

elements of the existing stand are retained throughout the

harvested area for the long term to attain specific objectives (Beese et al. 2003). 

Based on literature assessing forest influence, operational guidelines noted that individual or smaller groups of

trees should be no more than two tree lengths apart, and

that retained groups of trees should be at least 0.25 ha in

area. Within those guidelines, retention could encompass a

broad range in amount, type and spatial pattern. Two broad

types are recognized: dispersed retention throughout a cut

block (individual trees or small groups) and aggregated or

group retention (larger groups or patches of trees; fig.1).

These two types of retention can be used on the same cut

block, and are then referred to as mixed retention. 

Operational guidelines were not intended to be rules.

The variable part of VR recognizes that retention must be

flexible in response to many site-specific features (safety,

ecological values, silviculture, harvesting feasibility, economics, and visual aesthetics). Moreover, in sustaining 

biological diversity it is important to avoid doing the same

thing everywhere (Bunnell et al. 1999). Under any form of

retention, different groups of organisms will be advantaged

or disadvantaged. Variability is important to sustain as

many organisms as possible.

Within adaptive management, considerations about

actions are not limited to what you plan to do to achieve

objectives. They include what activities can be modified in

the future. Changeable elements of practice are direct links

to management and must be a focus of monitoring activities.

There are several features of retention that can be modified

– amount, patch or group size, type, spacing and ecological

features used to anchor patches. Because these features can

be modified, they are important elements of monitoring to

assess effectiveness. They also specify comparisons that

are part of the monitoring design – across levels of retention,

across patch sizes (or edge effects), across retention types,

or across different kinds of anchor points. 

Evaluating Success

Developing the monitoring program to evaluate success

is the most intellectually challenging part of adaptive management. I summarize three ideas related to evaluating

success: bounding the problem, monitoring questions,

and creating structured learning.

We so rarely bound the problem before undertaking to

solve the problem that Holling (1978) considered bounding

the problem a part of adaptive management. A monitoring

problem can be bounded in two broad ways. One is the

scope and definition of the problem; the second is the questions that will be asked. Scope and definition were addressed

at the outset. Two large issues were the spatial extent of the

program and the conceptual extent of biodiversity. The entire

tenure of 1.1 million ha was selected as the necessary scale

at which the maintenance of biodiversity would be addressed.

The conceptual extent of biodiversity was defined by the

criterion and indicators. 

Bounding the problem eliminates some potential features

or organisms as indicators. Our interest in the effects of

forest planning and practice on species richness excluded

some taxa as effective indicator species. Some species (e.g.,

salmon, marbled murrelets) spend most of their life at sea

and are greatly affected by events at sea where forestry

7
practices have little impact. Among species restricted to

land, some are influenced primarily by features other than

forest practices, or their response to forest practices is so

poorly known that their response provides no reliable guidance. Bounding the spatial and functional connections of the

problem encourages focus on those elements most likely to

provide guidance and control.

The process of bounding the problem and the monitoring program is facilitated when the following steps are

taken:

• Determine major issues. Our issues were to reserve

more old growth and implement a harvest system that

sustained native species richness. 

• Clearly define objectives and associated indicators of

success. This helps focus the monitoring on appropriate

variables. We used a single criterion and three broad 

indicators of success. 

• Identify the management plan and practices. The company decided that stewardship zones and variable retention were appropriate for addressing the major issues.

The approach to planning and practice became hypotheses to be evaluated by the monitoring process.

• Bound the problem. Establish the physical, functional

and conceptual boundaries. The goal is to delineate the

problem such that extraneous influences over which the

manager has little control, and which could mislead monitoring results, are reduced. Some large issues were noted

above. 

• Identify the major monitoring questions. A monitoring

design must ask the right questions to reduce statistical

uncertainty, properly estimate parameters from noisy 

data and assign probabilities to alternative hypotheses.

Questions selected for monitoring are listed below.

8

Figure 1—Examples of retention silviculture for Weyerhaeuser’s coastal tenure in British Columbia. Groups of trees are no more than 4 tree lengths apart;

individual trees are no more than 2 lengths apart.

Dispersed Retention Mixed Retention

Group Retention Group Selection
• Identify data needs. Although an assessment of current

conditions indicates broad knowledge gaps, specific

needs must be identified in terms of data best suited to

answer the specific monitoring questions.

• Rank the objectives or questions, and data needs.

Available resources for monitoring are limited. Ranking

or setting priorities is critical because it focuses on questions that present greater uncertainty and risks. Questions

selected for monitoring should be ranked and assigned to

specific objectives. What practices and objectives require

immediate attention and are more likely to have an impact

on biological diversity? Data needs may then be ranked

accordingly. 

There is nothing tidily linear about these steps, and the

process generally is iterative. 

Once the physical and conceptual nature of the problem

is bounded, the most compelling questions for the monitoring program can be determined. Monitoring questions

depend on the objectives, the practices, and on what we

know of the current conditions. They provide a set of

hypotheses and direct monitoring to areas where management requires information to adjust activities and avoid

unplanned and undesirable outcomes. The link between

monitoring and decisionmaking begins with the formulation of an agreement on the monitoring questions.

Uncertainties around management decisions and actions

were phrased as questions and winnowed down to 6 major

questions. These major questions are stated below in an

order that reflects increasingly large areas and longer time

frames. 

1) What is variable retention providing as habitat?

2) Are there major edge effects within aggregated variable

retention?

3) What is the best way of implementing variable retention

(e.g., types and amounts of retention)?

4) Is stand restoration effective at creating desired structures and ultimately restoring species distributions or

numbers where old growth is rare?

5) Are stewardship zones established in the most appropriate locations?

6) Is biological richness maintained over the tenure, given

the mix of zoning, variable retention and operational

constraints?

The questions represent the areas of greatest management concern, greatest uncertainty, and greatest ecological

risk in implementing the new approach to forest planning

and practice. Our ability to answer the questions determines how well the monitoring and modeling program

addresses the major issues of managers. 

Creating a structured system for learning is critical.

Although learning by challenging predictions is fast and

powerful, most predictions we can make for biodiversity

are nearly trivial. Comparisons, however, are powerful

ways to learn. Some comparisons are obvious – those

involving changeable practices (e.g., amounts and type of

retention). In most instances, it is possible to discern which

member of a comparison is more or less effective (but see

Bunnell and Dunsworth 2004). Targets, such as natural disturbance regimes, provide more equivocal guidance because

society rejects the entire range of natural disturbance or the

regime is difficult to quantify (e.g., Agee 1993, Cumming

et al. 1996). We chose most of our comparisons from changeable practices. They determine how we intend to acquire

knowledge. We used literature review and pilot studies to

determine what indicator measurements to use in making

comparisons. The what and the how are summarized in a

cross-design matrix (Kremsater et al. 2003: table 3).

The cross-design assigns the broadest array of indicators

to comparisons that are the highest priority or involve the

most pervasive practices. As well, it permits assigning the

most critical biodiversity indicators to several comparisons,

enabling some commonality of evaluation. Priorities are

based on literature review and pilot studies, and permit

thoughtful scaling back if budgets decline. Stratification

and blocking are necessary within the design to permit

effective scaling up to larger areas. Most comparisons are

focused on common operational practices that are amenable

to change. Experimental studies are used to extend the

common range of practice, ask specific questions, or when

pretreatment measures are revealing (e.g., slowly changing

variables with high spatial variability). Experimental studies

also permit more detailed evaluation of some mechanisms

that permit scaling up or projection through time. 

Closing the Feedback Loop

Linking findings of monitoring to changes in practices

closes the loop in adaptive management. A fundamental

question when developing any monitoring program is:

What would we do with the data if we had them? New

information collected by the monitoring program for adaptive management is of little use to practitioners if it does

not link to management practice. Linkage is provided by

9
both the evaluation system developed for each indicator,

and by descriptions of potential management actions that

are expected to help correct any failures (e.g., Bunnell et

al. 2003). The most frequent cause of failure in adaptive

management is the lack of subsequent action based on findings of monitoring (Lee 1993, Ludwig et al. 1993). Ability

to change may require a formal mechanism for accepting

results and associated management or policy changes. For

this reason three new structures were invoked within the

overall strategy. 

The Adaptive Management Working Group is composed primarily of researchers, including academics, consultants, company employees, representatives of companies

with adjacent tenure and government representatives. This

group’s charge has been to design the adaptive management approach and associated pilot studies, and refine the

concepts and scientific portion of the Coastal Forest Strategy.

The Variable Retention Working Group is composed of

practitioners who are responsible for the innovation and

practicality required to make the new practices work. Links

between these two groups helps ensure that scientific findings do feed back to management action. The International

Science Panel provides credibility through quality control

and guidance from a breadth of experience. The Panel also

helps evaluate the credibility of any findings of the monitoring program that are contrary to existing policy or regulations. The issue of managing to sustain biodiversity is

value laden and must connect with (and perhaps influence)

government regulation and policy. Each group has been

critical to making the process a success.

Brief examples for each major indicator illustrate closing

the loop. Management responses to analysis of Indicator 1

(ecosystems) already have occurred. Old-growth zones initially were delineated in a few large, contiguous areas. A

few were reallocated to improve both ecosystem representation and increase alignment with areas of public concern.

The main weakness within nonharvestable areas (underrepresentation of drier/warmer variants) was identified and

stimulated two actions: a pilot restoration program to develop

old-growth characteristics in riparian zones of the northeast

and west side of Vancouver Island, and an economic analysis of the costs of applying the program elsewhere (e.g.,

southeastern Vancouver Island). Evaluation of Indicator 2

(habitat) suggested no strong corrective measures, but helped

encourage the reduction of dispersed retention and increase

in mixed retention initially inspired by operational reasons.

Indicator 3 (organisms) affirmed those actions. For example, songbird responses suggested little difference from natural benchmark sites for group and mixed retention once

amounts of retention attained 20 percent. More details on

management response are found in Bunnell and Dunsworth

(2004).

ACKNOWLEDGMENTS

The nature of this project required a team effort. I have

acted as reporter. Individuals making major contributions

include W. Beese, B.G. Dunsworth, D. Huggard, L. Kremsater,

and J. Sandford. We all gratefully acknowledge the major

funders: Forest Investment Account, Forest Renewal BC,

NSERC, Weyerhaeuser. 

REFERENCES

Agee, J.K. 1993. Fire ecology of Pacific Northwest forests. 

Washington, DC: Island Press. 493 p. 

Beese, W.; Zielke, K. 1998. A forest management strategy 

for the 21st century. Silviculture – a new balance.

Nanaimo, BC: MacMillan Bloedel. 24 p.

Beese, W.J.; Dunsworth, B.G.; Zielke, K.; Bancroft, B. 

2003. Maintaining attributes of old-growth forests in

coastal B.C. through variable retention. Forestry

Chronicle. 79: 570-578.

Bunnell, F.L. 1997. Operational criteria for sustainable 

forestry: focusing on the essence. Forestry Chronicle.

73: 679-684.

Bunnell, F.L. 1998. Setting goals for biodiversity in managed forests. In: Bunnell, F.L.; Johnson, J.F., eds. The

living dance: policy and practices for biodiversity in

managed forests. Vancouver, BC: University of British

Columbia Press: 117-153.

Bunnell, F.L.; Chan-McLeod, A. 1998. Forestry and biological diversity: elements of the problem. In: Bunnell,

F.L.; Johnson, J.F., eds. The living dance: policy and

practices for biodiversity in managed forests. Vancouver,

BC: University of British Columbia Press: 3-18.

Bunnell, F.L.; Dunsworth, B.G. 2004. Making adaptive 

management for biodiversity work—the example of

Weyerhaeuser in Coastal British Columbia. Forestry

Chronicle. 80: 37-43.

10
Bunnell, F.; Dunsworth, G.; Huggard, D.; Kremsater, L. 

2003. Learning to sustain biological diversity on

Weyerhaeuser’s coastal tenure. Nanaimo, BC:

Weyerhaeuser. Chapters paginated separately.

http://cacr.forestry.ubc.ca/forest_strategy/am/framework.htm (11 January 2005).

Bunnell, F.L.; Kremsater, L.L.; Boyland, M. 1998. An 

ecological rationale for changing forest management 

on MacMillan Bloedel’s forest tenure. Pub. R-22.

Vancouver, BC: Centre for Applied Conservation

Biology. 281 p. http://cacr.forestry.ubc.ca/forest_stratgy/

pdf/EcologicalRationale.pdf (11 January 2005).

Bunnell, F.L.; Kremsater, L.L.; Wind, E. 1999. Managing 

to sustain vertebrate diversity in forests of the Pacific

Northwest: relationships at the forest level. Environmental Reviews. 7: 97-146.

Cumming, S.G.; Burton, P.J.; Klinkenberg, B. 1996. Boreal 

mixedwood forests may have no ‘representative’ areas:

some implications for reserve design. Ecography. 

19: 162-180.

Frankel, O.H.; Soulé, M.E. 1981. Conservation and 

evolution. Cambridge, UK: Cambridge University

Press: 327 p.

Franklin, J.F.; Berg, D.R.; Thornburgh, D.A.; Tappeiner, 

J.C. 1997. Alternative silvicultural approaches to timber

harvesting: variable retention harvest systems. In Kohn,

K.A.; Franklin, J.F., eds. Creating a forestry for the 21st

century: the science of ecosystem management.

Washington, DC: Island Press: 111-139.

Holling, C.S. 1978. Adaptive environmental assessment 

and management. New York: John Wiley and Sons. 377 p.

Kremsater, L.; Bunnell, F.; Huggard, D.; Dunsworth, G. 

2003. Indicators to assess biological diversity:

Weyerhaeuser’s coastal British Columbia forest project.

Forestry Chronicle. 79: 590-601. 

Lawson, B. 1996. Building materials, energy and the environment: towards ecologically sustainable development.

Canberra, Australia: Royal Australian Institute of

Architects. 135 p.

Lee, K.N. 1993. Compass and gyroscope: integrating science and politics for the environment. Washington, DC:

Island Press. 243 p.

Ludwig, D.; Hilborn, R.; Walters, C. 1993. Uncertainty, 

resource exploitation, and conservation: Lessons from

history. Science. 260: 17-36.

Mayr, E. 1997. This is biology: the science of the living 

world. Cambridge, MA: Belknap Press of Harvard

University Press. 323 p.

Meidinger, D.; Pojar, J. 1991. Ecosystems of British 

Columbia. Special Report Series No. 6. Victoria, BC:

BC Ministry of Forests. 330 p.

Mitchell, S.J.; Beese, W.J. 2002. The retention system: 

reconciling ‘variable retention’ with the principles of

silvicultural systems. Forestry Chronicle. 78: 397-403.

Naeem, S.; Thompson, L.J.; Lawler, S.P.; Lawton, J.H.; 

Woodfin, R.M. 1994. Declining biodiversity can alter

the performance of ecosystems. Nature. 368: 735-737.

Namkoong, G. 1998. Genetic diversity for forest policy 

and management. In: Bunnell, F.L.; Johnson, J.F., eds.

The living dance: policy and practices for biodiversity

in managed forests. Vancouver, BC: University of

British Columbia Press: 30-44.

Tilman, D.; Downing, A. 1994. Biodiversity and stability 

in grasslands. Nature. 367: 363-365.

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1 Professor, College of Forest Resources, University of Washington, Seattle, WA 98195, USA. Email: jff@u.washington.edu

Balancing Ecosystem Values Proceedings, Keynote Papers

Long-Term Studies: The Basis for

Science Based Resource Management

Jerry F. Franklin1

INTRODUCTION

Long-term observations are essential elements in the

science and application of resource management. Regardless

of how attractive and sound they appear, theories, models,

and management prescriptions ultimately are nothing but

untested hypothetical constructs until they are validated by

scientifically (including statistically) credible observations

made in the real world.

The ecological science used as a basis for much of our

management is largely composed of theories, often (mostly?)

untested (Franklin 1989). The long-term nature of much of

the relevant ecological science—such as the responses to

disturbances and patterns in stand development that occur

over many decades or even centuries—make validation

particularly challenging. Empirical data on the long-term

ecosystem responses to our manipulations are imperative.

Some of the necessary data can be collected as a part of

carefully designed monitoring programs, but scientific experimentation also needs to be part of the validation process.

Indeed, there are circumstances where monitoring can only

be effectively accomplished by conducting a carefully

designed experiment (Franklin et al. 1999a). 

ESTABLISHING LONG-TERM STUDIES

There are some important issues associated with the

development of long-term experiments designed to test 

theoretical constructs and management hypotheses. First,

the number of these experiments will be limited because of

the difficulty and expense associated with establishing and

maintaining long-term experiments in forest responses.

Hence, such experiments need to focus on major paradigm

13

shifts, such as fundamental changes in silvicultural practices.

The Demonstration of Ecosystem Management Options

(DEMO) experiment established in the Pacific Northwest

during the last decade meets that criterion with its focus 

on structural retention as a part of regeneration harvest

practices.

Second, these experiments need to be as robust as possible, since there are not going to be very many of them.

An important principle in making them robust is keeping

the designs relatively simple or clean. This is sometimes

referred to as the KISS principle: Keep It Simple Stupid!

Foresters often try to incorporate too many variables in the

same experiment, which almost invariably results in insufficient replication and often in confounding among variables.

Confounded experiments, where multiple variables are

simultaneously altered, seem to be a particular favorite of

silvicultural researchers with their focus on “silvicultural

systems” rather than fundamental variables, such as effects

of tree spacing and density on forest responses. 

These issues also relate to the second KISS principle

(KISS II)—Keep It Statistically Sound. Independence

among experimental variables (i.e., avoiding confounding),

strong contrast in selected levels of variables in the treatments (as opposed to small incremental changes), sufficient

replication, random assignment of treatments, and untreated

controls are all elements in addressing KISS II. 

The development of the DEMO experiment exemplifies

the difficulties of dealing with these issues (Franklin et al.

1999b). The initial design provided for a range of tree

retention from 0 to 100 percent but this was confounded

with the pattern of tree retention. The ultimate design was
primarily a 2 X 2 factorial design providing for a clean

comparison of retention levels (15 and 40 percent) and 

spatial pattern of retention (dispersed vs. aggregated). 

Data management is another major challenge in longterm research. Sufficient resources need to be available to

provide for quality control, data documentation (metadata),

and archiving/accessing. Researchers invariably want to

economize in this area, which is a serious and potentially

fatal mistake. Experience with the National Science Foundation’s Long Term Ecological Research program indicates

that about 25 percent of the budget needs to be allocated to

data management. Fundamentally, the question is, Are the

data worth collecting or not? If they are, then they must be

adequately managed or their value will be lost. 

Obtaining sufficient resources and organizational commitment to sustain long-term research (experiments) and

monitoring is probably the greatest challenge. Most organizations—governmental and otherwise—operate on the basis

of annual budgets and in an environment of constantly

changing priorities. The emphasis is ever on the short term.

About the only way of assuring long-term support may be

creation of a trust or endowment for long-term studies, an

approach with which few organizations are experienced or

inclined. The Nature Conservancy is one organization that

has created endowments for funding of long-term monitoring

programs. 

Finally, committed individuals are critical to long-term

research. Champions are needed to get such programs established to carry them forward (Strayer et al. 1986). Unfortunately, these individuals often suffer a professional penalty

since most reward systems do not adequately recognize the

value of such contributions.

CONCLUSION

In conclusion, long-term studies are absolutely essential

to scientifically-based resource management. The challenges

to successfully conducting long-term studies are immense,

however, including the difficulty of finding and sustaining

the necessary resources. Organizations involved in research

and management of natural resources, particularly the USDA

Forest Service, were critical in developing and supporting

long-term research during much of the 20th century; we

need to remember these roots and reaffirm our commitment

to this scientific infrastructure. 

In developing long-term experiments: 

Keep them simple 

Keep them statistically credible 

Think outside the box (or at least beyond it) 

Devote the necessary resources to data management 

Build the capacity for sustaining the long-term studies

(e.g. establish trusts, publicize the studies to provide recognition or “profile”, and “leave footprints”

for future generations.)

Provide leadership 

REFERENCES

Franklin, J.F. 1989. Importance and justification of longterm studies in ecology. Likens, G.E., ed. Long-term

studies in ecology. New York: Springer-Verlag: 3-19.

Franklin, J.F.; Harmon, M.E.; Swanson, F.J. 1999a. 

Complementary roles of research and monitoring:

lessons from the U.S. LTER Program and Tierra Del

Fuego. Aguirre-Bravo, C.; Franco, C.R., comps. North

American Science Symposium toward a unified framework for inventorying and monitoring forest ecosystem

resources. Proceedings. RMRS-P-12. U.S. Department

of Agriculture, Forest Service, Rocky Mountain

Research Station: Fort Collins, CO. 284-291. 

Franklin, J.F.; Norris, L.A.; Berg, D.R.; Smith. G.R. 1999b. 

The history of DEMO: an experiment in regenreation

harvest of northwest forest ecosystems. Northwest

Science 73(special issue): 3-11.

Strayer, S.J.; Glitzenstein, S.; Jones, C.C. [et al.]. 1986. 

Long-term ecological studies: an illustrated account 

of their design, operation, and importance to ecology.

Institute of Ecosystem Studies Occasional Publication

1. Milbrook, NY: Institute of Ecosystem Studies. 

14
1, 2 Institute of Forest Management; Georg-August-University Göttingen, Büsgenweg 5, D-37077 Göttingen, Germany. 

Email for corresponding author: kgadow@gwdg.de

Balancing Ecosystem Values Proceedings, Keynote Papers

Forest Management:

Science-Based and Understandable

Klaus von Gadow1 and Christoph Kleinn2

INTRODUCTION

The initial theoretical basis for sustainable forest management was established during the early 19th century by

scientists who developed the principles of sustainable harvest control and discounted cash flow analysis (Faustmann

1849, Hundeshagen 1826). Empirical yield data were needed

to apply these general theories in concrete practical situations.

Such data were derived from long-term growth and yield

studies or provenance trials (Pressler 1865, Schwappach

1890, Spellmann and Schober 2001) and used to develop

ABSTRACT

The objective of forest research is to reach a better understanding of biological and economic systems and to generate

information that is useful for management. An important objective of forest management, on the other hand, is to use this

information, but this is not a trivial task. These two objectives are not always easy to match in an increasingly fragmented

scientific environment which rewards highly specialized investigation. This paper presents a simple concept that is capable

of matching the objectives of forest research and management. It is often postulated that forest management should be sustainable, based on validated research results, conform to acceptable environmental standards, and understandable to the 

public. These objectives may be difficult to achieve, but it may be possible to come within reach of them if the following

requirements are met:

1. A variety of forest development paths are designed and evaluated by different scientific disciplines, 

2. Management activities are effectively monitored in the field,

3. Forest management practices are understandably demonstrated in the field.

Based on these assumptions, a practical framework for science-based management of a forested landscape may include

three elements. These elements are presented here under the three headings: forest design, research and demonstration, and

harvest event analysis. We will first give a brief overview of forest management systems, then discuss different types of

field experiments and finally show how research and management can be linked. This concept can be used to make accessible at least some of the wealth of information that is available within an increasingly specialized and fragmented scientific

landscape.

KEYWORDS: Research and demonstration, designing forest development, harvest event analysis. 

15

flexible growth models for different levels of resolution

(Burkhart 1987, Ek and Monserud 1974, Gadow 1984,

Pretzsch 2001). The growth models are essential tools for

evaluating future treatment options for complex forest ecosystems. Evaluating treatment options has become a nontrivial task because societies demand integrated and wideranging approaches to forest management that address

social, ecological, and economic goals. The matter is further complicated by the fact that the demands of society are

not constant. The objectives of forest management are not

only numerous, they are continually changing. 
The objective of forest research is to reach a better understanding of biological and economic systems. Management

needs to utilize this understanding, but this is not a trivial

task. This paper focuses on matching the objectives of forest research and management. We present a science-based

forest management concept which includes three elements:

an approach known as forest design, a system of field

research and demonstration, and a monitoring concept

which is known as harvest event analysis. We will first

give a brief overview of forest management systems, then

discuss different types of field experiments, and finally

show how research and management can be linked. This

concept can be used to make accessible at least some of the

information that is available within an increasingly specialized and fragmented scientific landscape.

FOREST MANAGEMENT SYSTEMS

Forests represent a remnant wilderness with high recreational value in densely populated information societies, a

natural resource threatened by elimination in impoverished

regions, and a renewable reservoir of essential raw materials for the wood-processing industry. Approximately 2908

million ha or 23 percent of the continental surface has been

classified as productive forest and subdivided by Solberg

(1996) into 5 categories of forest management. By using a

somewhat simplified classification based on the development of timber volume over age or time, two archetypical

types of sustainable forest management3 system may be

distinguished (fig. 1).

Rotation forest management (RFM) systems with fastgrowing timber species and intensive silviculture are found

in the Southern Hemisphere (Chile, South Africa, Australia,

New Zealand), the southeastern United States, many parts

of Asia, and the Mediterranean region. According to

Cossalter and Pye-Smith (2003), the increase in human

population and economic development in most countries

result in a continuously rising demand for wood. Wood is

currently the fifth most important product traded worldwide.

Vast quantities of wood are harvested to provide fuel, fibers

(pulp, paper products, board), sawn timber and veneer

(construction, furniture, packaging) and raw material for

a future “ligno-chemical” industry. It is estimated that an

extra 100 million ha of cultivated forests will be needed by

the middle of the 21st century to satisfy the potential future

demand for wood. At the same time, there are serious concerns about the sustainability of cultivated forests and their

perceived low resistance to disturbances such as storms or

pest outbreaks. Monocultures are generally viewed in a

negative light in connection with biodiversity conservation,

and there is a need to address these concerns and to identify

potential risks associated with plantation forestry (Cossalter

and Pye-Smith 2003). 

Continuous-cover forest (CCF)4 management systems

are characterized by selective harvesting and are most frequently found in densely populated industrialized regions

and in some tropical forests. In CCF management the stand

age is undefined and forest development does not follow a

cyclic harvest-and-regeneration pattern. Instead, it oscillates around some “ideal” level of growing stock. Harvest

control is based on some ideal diameter distribution (Guldin

1991, Laughton 1937, Leak 1964, Meyer 1933, Mitscherlich

1952, Schütz 1994, Susmel 1980, Virgilietti and Buongiorno

1997). The mean annual increment is not appropriate for

16

Figure 1—Development of biomass (v) over age or time for two archetypical systems of forest management: rotation management

systems (left) and continuous cover forestry systems (right).

3 Nonsustainable forest management is characterized by sporadic exploitation (without regeneration) of a forest resource which contains some trees that 

are considered worth harvesting.

4 The terminology is not always clear: CCF management is characterized by selective harvesting and the use of natural regeneration; selective harvesting

techniques are also practiced in the so-called “near-natural forest management,” favoring site-adapted tree species and some kind of “natural forest management.” 
measuring productivity and the traditional sustainability

criteria, such as the normal growing stock, are not applicable.

Considerable forest areas in Europe and other parts of the

world are currently being converted from RFM to CCF

systems (Pommerening 2002, Spellmann 1998). A consequence of the conversion policy is that particular emphasis

is placed on specific silvicultural methods to facilitate the

transition from clearfelling systems to “near-natural” forest

management. Continuous-cover forestry systems are often

preferred by private forest owners because of cost savings

for planting or tending operations and a potential for a

high-value increment of certain tree species. Continuouscover forestry systems are also attractive for public forest

administrations in regions where environmental concerns

and habitat conservation are important issues (Otto 1994,

Pommerening 2001, Sturm 1995).

FOREST FIELD EXPERIMENTS 

Credible forest management is based on empirical

research, and the aim of the early field experiments established during the 19th century was to measure timber yields

on different growing sites in response to specific thinning

treatments. Some of these experiments have been remeasured for over a century, providing valuable information 

on long-term developments (fig. 2, Pretzsch 2001). 

The value of information to be gathered in forest experiments has to be weighed against the estimated cost of collecting it. Not only are the available resources limited, but

time is also a major constraint. Furthermore, the validity

and effectiveness of an experiment is influenced by its design

and execution. Thus, attention to the planning of field

experiments is important. We may distinguish manipulated

experiments and observational studies. 

Manipulated Experiments

A manipulated experiment is an investigation that establishes a particular set of circumstances under a specified

protocol with the aim of testing a hypothesis. The adjective

“manipulated” implies the establishment of a set of predefined treatments which allows comparison of the effects or

responses resulting from these treatments (Cox 1958, Fisher

1935). Thus an experiment deliberately imposes a treatment on a group of objects in the interest of observing the

response. A typical example of a manipulated experiment is

the Pinus radiata study at Glencoe Hill in South Australia.

Beginning in 1985, five sites were established across a

range of ages, soil types and stand productivity. Each site

was established with four replicates of plots representing 

3 thinning and 12 fertilizer treatments in a 31 x 44 factorial

design. The objective was to evaluate differences between

thinning and fertilizer treatments, where they existed. The

establishment of the experiment necessitated finding large

sites of at least 70 ha which were relatively homogeneous

in terms of age, site quality, soil type and stand density.

The choice of sites that met all these criteria was extremely

limited (O’Hehir 2001). Another example of a manipulated

experiment conducted in the Northern Hemisphere is the

Roof Project established in the Solling Hills of northern

Germany. The aim of the Roof Project was to evaluate 

the effects of changes in environmental conditions on a

Norway spruce (Picea abies) ecosystem, based on manipulated input of nutrient and water supply (Dohrenbusch et

al. 2003). The roof experiment consists of 4 plots, a control

plot (D0); a clean rain roof (D1) where the precipitation is

demineralized and subsequently enriched with sodium

hydroxide and a nutrient solution that is applied to the

ground under the roof; a control roof (D2) where the precipitation is not modified; and a drought/ rewetting roof

(D3) that is used to simulate drought conditions. There are

many examples of such manipulated field experiments.

Depending on their scope, their establishment and maintenance may be very costly because—particularly in silvicultural and growth-and-yield experimentation—relatively

large experimental plots and relatively long time periods

are needed (Kleinn and Köhl 1999).

17

Figure 2—Diagram showing the development of different types of forest

field experiments (after Mårell and Leitgeb 2004). Growth and yield studies evaluate tree growth, provenance trials the suitability of certain species

to given site conditions; fertilization trials the effect of fertilizer applications to tree growth, and catchment studies the effects of afforestation on

the water yield. The International Union of Forest Research organizations

(IUFRO) is an international network of scientists involved in studying

trees and forest ecosystems. 
Some of these experiments are remeasured for more

than a century. A particularly interesting example of a longterm field study is the CCT5 spacing experiment established in South Africa during the 1930s by A.J. O’Connor

(Gadow and Bredenkamp 1992: 55). Most of the CCT

experiments consist of 9 to 18 plots each covering 0.04 ha,

sometimes with up to 4 replicates. The basic series includes

9 plots, representing a range from extremely low to very

high densities, and thus provides answers to such fundamental questions as the maximum density that can be expected

on a given site, or the relation between stand density and

biomass production. Selection and definition of sites for

manipulated experiments is usually a directed selection following criteria of homogeneous conditions and minimum

size. It is not a randomized selection as used, for example,

in forest inventories.

Comparative Observational Studies 

A controlled experiment deliberately imposes treatments

on experimental plots with the aim of observing a particular

effect/response. This differs from an observational study in

which the actual status of a population is to be assessed. A

hybrid type of study is the comparative observational study

which involves collecting and analyzing data from different

site conditions but without actively predefining or changing

these conditions, i.e., without applying treatments (Kuehl

1994). There are manifold examples of comparative observational studies in forestry and in other disciplines. Typical

in forestry are tree growth plots established on sites with

different growing conditions to evaluate specific growth

patterns in response to the observed conditions at the beginning of the growth period. The treatments (different site

conditions) are not imposed and controlled by the researcher.

Examples are the experimental growth and yield plots in

Malaysia described by Teng (1999). The ultimate aim of

these studies is external validity, the ability to generalize

from a limited set of observations. No one is interested in

observations that cannot be extended beyond the particular

restricted set of available data, but the ability to generalize

depends on whether the observed response measurement is

a representative one. We need to clarify whether the study

sites were a representative sample and whether the results

of the observations may be legitimately extended to the

relevant general population. Helpful in this regard is a comprehensive description of the study sites and of the methodology that was used, so the reader can judge whether the

results are applicable to a particular situation.

Comparative observational studies are also known as

quasi-experiments (Campbell and Stanley 1963, Cook and

Campbell 1979). One reason for doing quasi-experimental

research is to capture a sufficient number of different conditions. The intention may be to observe changes in tree

growth and to attribute these changes to some variable such

as the development of air temperature or carbon dioxide

concentration over time. Observational studies tend to

involve many different and interacting relationships between

variables, and it often happens that much of the variability

cannot be explained by the available observations. Statistical

inference from these studies should be interpreted as “testing differences between different conditions” and not as

“testing effects” unless further evidence (external to the

experimental study) points to the existence of a cause-effect

relationship. However, observational studies are carried out

on a default basis in most regions, such as forest management inventories to support forest management planning

and large area forest inventories to support forest policy

formulation. It is, therefore, highly desirable to use those

data also to analyze cause-effect relationships and to test

hypotheses (such as the relationship between forest health

status and proximity to industrial facilities, or the relationship between site conditions and tree growth). Schreuder

and Thomas (1991), in an excellent paper, discuss the

methodological implications when using forest inventory

data to establish cause-effect relationships. 

Due to lower maintenance costs, observational studies

have become very important during the past decades. They

may be classified as long-term, temporary, and interval

studies. A disadvantage of long-term studies is the high

maintenance cost of the research infrastructure and the long

wait for data. The object of the trial is not always achieved

because plots may be destroyed prematurely by wind or

fire. Temporary plots, also known as chronosequences, are

measured only once but cover a wide range of ages and

growing sites. Thus, the sequence of remeasurements in

time is substituted by simultaneous point measurements in

space. This method has been used extensively during the

19th century (Assmann 1953, Kramer 1988: 97, Wenk et al.

1990: 116). Chronosequences may provide information relatively quickly, but they do not capture rates of change in

response to a known initial state. A compromise may be

achieved by using a system of observational studies, or

interval studies, which maintain the advantages of permanent (change rates) and temporary plots (broad coverage of

initial states and minimum wait for data). Interval plots are

18

5 CCT means “correlated-curve-trend” and refers to a particular way of describing the effect of stand density on tree growth. 
measured at least twice. The interval between the measurements is sufficiently long to absorb short-term effects of

climatic fluctuations (for details, see Gadow and Hui 1999). 

Multidisciplinary Forest Ecosystems Research

Networks and Platforms

Many of the more recent forest field experiments have

become multidisciplinary in scope. The silvicultural treatments employed in these experiments are designed by

teams which include scientists with different backgrounds

and traditions. These studies represent major investments,

and their objective is to meet increasing public demands

for forests that provide healthy environments for people,

support biological diversity, and sustain economic productivity (Peterson and Monserud 2002). Several research networks have been established with the aim of providing data

for projects, research units and experts dealing with forest

ecosystem research. An example was the European forest

ecosystem research network (EFERN) initiative which was

funded by the European Commission (ifff.boku.ac.at/efern).

From 2001 to 2003, the European network for long-term

forest ecosystem and landscape research (ENFORS) conducted a survey of valuable forest field research and monitoring facilities (see www.enfors.org). Most of the forestry

research networks were created during the past 20 years,

mainly in response to the air pollution and forest dieback

issues (see Mårell and Leitgeb 2004). 

LINKING FOREST RESEARCH 

AND MANAGEMENT

It is often postulated that forest management should be

sustainable, based on validated research results, conform to

acceptable environmental standards, and understandable to

the public. These objectives may be difficult to achieve, but

it may be possible to come within reach of them if the following requirements are met:

1. A variety of forest development paths are designed and

evaluated by different scientific disciplines, 

2. Management activities are effectively monitored in the

field,

3. Forest management practices are understandably demonstrated in the field.

Based on these assumptions, a practical framework for

science-based management of a forested landscape may

include three elements: forest design, research and demonstration and harvest event analysis. 

Forest Design

Forest planning can reduce uncertainty in management

outcomes by anticipating the future in a systematic way,

thus reducing the likelihood of unexpected events. It can

also improve the likelihood that future developments will

agree with specified objectives. Forest planning requires

tools that are understandable and easy to use, support a

negotiation process, and can assist in reaching widely

acceptable decisions relating to the management of trees

and forests. The Multiple Paths Model is one such tool.

This model assumes that a forested landscape is an aggregation of spatially defined land parcels of different sizes

and shapes, that each parcel is characterized by a specific

tree population with a given set of attributes, that multiple

development paths are available for each individual land

parcel, and that each path has a value.6 This theory and its

technical implementation can be used in any managed

ecosystem with any set of objectives; it is spatially explicit,

combining stand-level objectives and landscape-level constraints. This concept is easy to understand. It provides an

excellent basis for incorporating knowledge from different

scientific disciplines (see applications by Bettinger et al.

1997, Chen and Gadow 2002, Öhman and Eriksson 1999). 

The Multiple Paths Model represents a generic theory

of forest development which is suitable for any arbitrary

silviculture. A scenario for a forested landscape as a whole

is a specific combination of management paths in all the

individual land parcels. It is possible to compare the different scenarios and to identify the more desirable ones. The

basic approach is well established. An important task is to

generate realistic treatment schedules for the different land

parcels. A treatment schedule, a path, is uniquely defined

by a succession of harvest operations. Each harvest operation is followed by natural growth. A series of paths can be

generated by using a growth model and a thinning model.

A thinning model is an algorithm which translates the

adjectives used by foresters to describe a harvest operation

(high/low/heavy thinning) into a specific protocol which

identifies the trees that will be removed. Examples of such

thinning models are given by Albert (1998) for beech forests,

Staupendahl (1999) for spruce forests and Rautiainen (1999)

for a dipterocarp forest. Different thinning types, applied

during successive periods, generate a variety of development paths, each representing a unique treatment schedule

19

6 A path is characterized by a specific succession of management activities followed by natural growth. 
for a given land parcel which can be evaluated and compared with other schedules, based on the experience of 

various scientific disciplines.7

Research and Demonstration

The ultimate objective of forest research is to generate

information that is useful for management. An objective of

forest management, on the other hand, is to use this information. These two objectives are not always easy to match

in an increasingly fragmented scientific environment which

rewards highly specialized investigation. A possible solution may be found in the establishment of a system of

observational field trials known as research and demonstration areas (RDA). As the name implies, the purpose of a

RDA is to gather empirical observations about the resource

and at the same time to present the information to an interested audience (fig. 3). 

Based on the work by Nöllenheidt (2000) for example,

a research and demonstration area in Europe may represent

the core area within a management demonstration forest

covering only a few hectares. Roschak (1998) assessed the

diameters, heights, and position coordinates of all trees

within such an area. These data provide detailed information about the species, size distributions, and the spatial

structure, as well as the changes caused by a harvesting

operation. Assessments are not limited to one discipline.

Thus, RDAs can be used to obtain comprehensive empirical data about forest development in response to specific

treatments. These areas are particularly useful for education

and training. The size of an RDA is often related to the

operational areas required by forest management. For

example, although large plots are more common in North

America, small areas may be more suitable in Europe where

forestry is practiced on a smaller scale. Interval plots, measured twice and spread over a range of growing sites, development stages and silvicultural treatment categories, combine

the advantages of the permanent plot (change rates) and the

temporary plot (minimum wait for data). 

Harvest Event Analysis

A harvest event involves a drastic modification of many

forest conditions, and foresters are not always aware of the

consequences (Zucchini and Gadow 1995). It is not only

possible, but also quite simple and logical, to combine the

activities of management monitoring and resource assessment. This combination may be achieved by timing the

assessment so that it coincides with a harvest event. Most

resource assessment activities are scheduled to take place

at regular intervals (causing the data to become invalid

after the next harvest) or immediately after a harvest (to

evaluate the damage done by the harvesting activities). A

harvest event assessment captures stand data immediately

after the trees have been marked for removal but before

they are cut. Thus information is available about (a) the

forest condition before harvesting, (b) the removed trees

and (c) the forest condition after the harvest. A harvest

event analysis can then be employed to evaluate the management-induced changes to the ecosystem. The removal of 

a tree modifies the spatial distribution of the temperature 

and radiation and influences a variety of biogeochemical

20

Figure 3—An important objective of a research and demonstration area is to measure change rates of certain

variables (W) per unit of time (t) in response to a given set of conditions at time t1 (left). The change rates

provide a basis for generalizations, for example about the basal area change rates in response to a given

initial basal area and age (right). 

7 Further details of the constrained optimisation approach may be found in Clutter et al. (1983), Gadow and Puumalainen (2000), Lappi (1992), 

Pukkala et al. (1995), Ware and Clutter (1971).
processes. Thus, harvest events may be evaluated in terms

of a change in forest density, forest structure and forest

value (fig. 4). 

A harvest event analysis was done countrywide in South

Africa during the 1970s and 1980s. The method, which was

then known as “thinning control,” involved a systematic

sampling in all units that had been marked for thinning. The

analysis involved a quantitative evaluation of the economic

effects of a pending thinning operation, before the operation would be carried out. It proved to be a very effective

method of preventative control and comprehensive monitoring. 

For several years, harvest event analysis has been an

important part of the curriculum at the Forestry Faculty in

Göttingen, Germany. A harvest event is an ideal opportunity

for bringing together various disciplines. The basic event

analysis, involving modifications of forest structure and

growing stock value, is complemented by an evaluation of

the effects of a particular harvest operation on the soil conditions, the habitat quality relating to a variety of organisms, the genetic structure of the tree population, and the

forest microclimate. The method is specifically appropriate

in uneven-aged, multi-species forests managed in the selection system where the multiple effects of a particular harvest operation are not always immediately evident.

CONCLUSIONS

A managed forest ecosystem may be seen as an enterprise which produces a comprehensive set of goods and

services and which constantly needs to adapt its production

processes and its range of products in response to an evolving market. This objective can be achieved if research is

made accessible at different levels, as in other enterprises.

Thus, it is often postulated that forest management should

be sustainable, based on validated research results, conform

to acceptable environmental standards, and understandable

to the public. These objectives may be difficult to achieve,

but it may be possible to come within reach of them if the

following requirements are met:

1. A variety of forest development paths are designed 

and evaluated by different scientific disciplines, 

2. Management activities are effectively monitored in

the field,

3. Forest management practices are understandably 

demonstrated in the field.

Based on these assumptions, a practical framework for

science-based management of a forested landscape may

include three elements: forest design, research and demonstration, and harvest event analysis. The ultimate objective

of forest research is to generate information that is useful

for management. An important objective of forest management, on the other hand, is to use this information. These

two objectives are not always easy to match in an increasingly fragmented scientific environment which rewards

highly specialized investigation. 

Figure 5 presents a simplified diagram of a forest management system which is based on continuous research

involvement. Designing forest development and analyzing

forest events present ideal opportunities for bringing together

various scientific disciplines and to utilize their combined

experience more effectively. 

Research and demonstration areas are used to gather

empirical observations, and to demonstrate different management alternatives in the field. Response models which

estimate the response of certain variables to a set of initial

conditions are obtained in such RDAs. Treatment models

21

Figure 4—A harvest event may be evaluated in terms of a change in forest density, forest structure and forest

value. The diagram shows a hypothetical forest section which may be modified by a harvest event in different

ways; different shadings represent different tree species, crossed trees are marked for harvesting. 
which mimic the modification of forest structure based on

a certain forestry vocabulary may also be based on information

gained from RDAs, but mainly will be based on harvest

event analyses. Both, response and treatment models are

essential for generating alternative paths of forest development. The information about the different paths provides

the necessary basis for a science-based forest design, which

can be evaluated by the different disciplines. 

A harvest operation may reduce forest density and

modify the spatial structure, the species composition, the

ecological conditions for a great variety of organisms, and

the value of the standing crop. Harvest event analysis is a

method designed to make various effects of a given management activity visible by simultaneously producing information about the forest before a harvest event, the removed

trees, and the forest remaining after the harvest event. The

analysis thus provides data about changes, which may be

evaluated by different disciplines. These data, in turn, are

needed for developing growth models, thinning models,

and possibly hazard models. 

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1 Centre for Applied Conservation Research, Faculty of Forestry, Forest Sciences Centre, 2045, 2424 Main Mall, Vancouver, BC V7W 2W7, Canada.

Email: innes@interchg.ubc.ca

Balancing Ecosystem Values Proceedings, Keynote Papers

Long-Term Forest Experiments: 

The Need to Convert Data Into Knowledge

John L. Innes1

INTRODUCTION

Some of the earliest formal experiments in forestry,

started in the 19th century, continue today. Most of these

long-running experiments are related to growth and yield

studies under differing environmental and management

conditions and deal with stand-scale experiments. For

ABSTRACT

Long-term forest experiments are a critical part of innovation in the forestry sector. However, most such experiments are

challenged for funding and have suffered from the emphasis that some funding agencies are now placing on the provision of

short-term results. To be successful, project managers must demonstrate that they can produce both short-term and long-term

results. They need to involve interdisciplinary teams in the research, and preferably need to diversify their funding sources

to ensure long-term funding stability. Although it is always difficult to change the objectives of an experiment mid-way,

researchers need to be aware that priorities change and the relevance of a particular project to societal problems can change.

Many long-term experiments involve the accumulation of large amounts of data. Therefore, a strategy for ensuring the

quality and long-term storage of these data is essential. The data need to be accessible to those capable of analyzing the

material; these may not necessarily be the same people as those collecting the data. Greater use needs to be made of information management tools such as the Natural Resources Information Network (NRIN) and the Global Forest Information

Service (GFIS), as well as ensuring that projects are registered with major international networks, such as the International

Long-Term Ecological Research (ILTER) network.

For the results of long-term experiments to be of value to the forestry community, an effective strategy is needed to

ensure that the data are converted into knowledge and that this knowledge is conveyed effectively to the end-users. In the

United States, this has occurred largely through the extension personnel of the land-grant universities, although these extension specialists have tended to work mostly with the private sector. There is a need to recognize that the potential end-users

of the knowledge derived from long-term experiments are varied, and that the means to communicate that knowledge to them

will differ accordingly. Traditionally, there has been a reliance on written communications, but other means of communication need to be explored and developed if the full benefits of the research are to be realized. In particular, recent developments in visualization technology are new tools available to the researcher, and greater advantage of these needs to be taken

when explaining the future options that research is revealing for particular forests.

KEYWORDS: Information management, research funding, extension, data quality, data management.

25

example, in Switzerland, there are several on-going, longterm experiments that date back to the late 19th century.

Trees have been periodically re-measured, and the results

have helped develop the scientific basis for the type of silviculture known as “Plenterwald,” more commonly referred

to in English as uneven-aged forestry (Schütz 1997). Other

experiments relate to the development of forested land after
disturbance, with the time series from Rothamsted, England,

being one of the longest (two small areas were fenced off

to observe woodland development in 1882 and 1886)

(Harmer et al. 2001). These early experiments and observational studies, virtually all of which come from Europe, are

very long term, but generally involve very small areas. 

More recent long-term experiments include the watershed manipulations established in North America and

involve much bigger areas (Hubbard Brook in the United

States is the classic example – http://www.hubbardbrook.org).

Experiments at this scale enable the effects of stand and

forest treatments on factors such as wildlife species to be

determined in a more reliable fashion than is possible in

most European experiments. However, very few, if any, of

the North American experiments extend more than 50

years. This means that very few studies extend across a

whole rotation.

There are also several long-term experiments that have

been established in the Tropics, such as the long-term studies at Pasoh, Malaysia (Kochummen et al. 1990). Within

this context, it is relevant to mention the large-scale forest

fragmentation experiments conducted in Brazil (e.g.,

Offerman et al. 1995). Some of these are genuine experiments, involving manipulation and replication; others are

more akin to case studies. All are potential sources of highquality datasets that can be used to generate information of

considerable value to forest managers, forest policy makers

and others. 

In all examples, the long-term studies are characterized

by the collection of very large datasets. The intention is

often to gather sufficient data to assess the impacts of particular forms of management on specific forest values such

as water quality and species diversity. However, this intention has not always been successfully achieved. In this

paper, I review some of the problems associated with the

establishment, continuation and use of large-scale, longterm experiments, with particular emphasis on the need to

justify the cost of such experiments through the application

of the knowledge that is generated from them.

CHALLENGES ASSOCIATED 

WITH IMPLEMENTING LONG-TERM

EXPERIMENTS

All long-term forest research sites face many challenges.

Perhaps the biggest is that although the value of the data

tends to increase over time, the risk that the original research

question is no longer relevant also increases. Experiments

are often set up to test the assumptions associated with a

particular practice, but extraneous factors can result in the

practice being introduced before the research results become

available. Once a policy decision is made, it may undermine the original objectives of the project, making it very

difficult for the project manager to justify further funding.

For example, as the various forms of variable retention

become entrenched in mainstream forest management practices in western North America, comparisons of such treatments with clear-cuts may no longer be relevant. Project

managers faced with such a situation need to argue that

even when a decision has been made to change practices, it

is important to gain scientific understanding of the implications of the change. This is particularly true given that most

policy changes occur fairly quickly, generally well before

the results of long-term experiments can be expected. With

increasing emphasis being given by policy makers to science-based forest management, there is always a need for

experiments that demonstrate that such management is in

fact based on science.

As policy priorities are constantly evolving, managers

of long-term research sites must be sufficiently flexible and

innovative to enable their data to be applied to new and

emerging problems as they arise, a requirement that may at

times seem contrary to the principles of experimental design.

For example, the Swiss Long-Term Forest Ecosystem study

was set up in the mid-1990s with the specific intention of

including both short-term and long-term research (Innes

1994, 1995). The study provides a platform for forest

research to be undertaken by maintaining detailed records

of meteorology, soil conditions, forest health and other 

routine observations in a suite of plots across the country.

Monitoring data are shared between scientists involved

within the project. Individual project scientists can work on

a particular problem on one or more of the research sites,

on condition that they share their results through publications, extension and other means. The plots, however, are

very small (1 ha) and have only one (adjacent) replication,

and it will be difficult to make any country-wide generalizations from the results. The small size of these plots also

severely restricts the type of study that can be done effectively on the plots, with most studies of larger vertebrates

being of questionable value.

Relevance is a critical issue and can significantly affect

the possibilities of obtaining funding for long-term experiments. With budgets for forestry research shrinking around

the world, increasing pressure is being placed on funding

managers to provide financial support for only those projects that are guaranteed to produce results in the short-term.

Managers of research funds are under increasing pressure

to show “value for money,” and this inevitably is measured

26
in relation to short-term results and impacts. This occurred

in British Columbia, Canada, in 2002 and 2003 when the

funding agency for forest research (Forest Innovation

Investment Ltd.) decided that all research projects had to

be completed within a year. As the formal notifications of

project success were issued late in both years, the actual

amount of time available to conduct the research was considerably less than a year (4 months in some cases). Such 

a funding policy does not tend to favor long-term research,

and even short-term research can be compromised.

Leaders of long-term research studies need to address

the tendency to focus on short-term results by examining

what data they can deliver in the short term, and what they

can better deliver in the long term. For most policy and

decisionmakers today, it is simply insufficient to claim that

a project will generate exceptionally useful results 30 years

from now. Policy works over much shorter timescales, 

normally reacting to events rather than being visionary or

strategic. Consequently, there is pressure to interpret results

prematurely, with all the problems that this entails. An

important aspect related to this is the need for researchers

to demonstrate actively the relevance of their work. It is no

longer appropriate simply to publish in the scientific literature and hope that the results will somehow filter through

the end-users. An active and aggressive program promoting the results among end-users may be necessary, and

researchers need to be aware that there is often considerable

inertia in the uptake of new research. Although funding

managers believe that it is possible to “measure” the impact

of research on management practices or even decisionmakers,

this is rarely possible, and attempts to do so may produce

spurious results.

It is sometimes easier to establish a new research program than to implement what is already known, and new

programs frequently fail to take into account either the policy needs or on-going long-term research experiments. This

has happened in British Columbia, where a whole series of

new initiatives in the 1990s were inadequately linked to

policy and research (Innes 2003). To be successful, researchers,

practitioners and policy makers need to work together to

identify common priorities. Although this is increasingly

happening during the design of research programs, it does

not occur frequently enough during the design phase of

long-term experiments.

Apart from relevance and funding, long-term forest

research faces several other difficulties. Many of these surround the issue of data collection and storage. For example,

the rapid development of analytical technologies means

that many chemical data are now recorded at concentrations

well below the detection limits of early equipment. Automatic data collection and enhanced storage mean that data

can be collected relatively easily (such as from automatic

meteorological stations). It is sometimes difficult to decide

the resolution at which data should be collected and

archived, although experience tends to suggest that in longterm experiments, the highest resolution possible is the

most appropriate as model calibration and other data needs

become increasingly sophisticated. Although storage capacity used to be a problem, data storage capacity today is not

a major issue. However, the development of electronic data

storage and automatic wireless transfer of data from a collection site to a central repository mean that very large volumes of data are routinely collected. As a result, data

handling techniques are continuously changing, and great

care is needed to ensure that data are properly archived.

Most research institutions have protocols designed to ensure

the security of datasets (such as automatic backups and offsite storage of duplicates of data archives). However, where

such facilities do not exist, they need to be implemented.

Over long time periods, individual researchers come

and go, as do their institutions. Data are frequently lost or

corrupted; yet today, there are few excuses for the loss of

valuable data. More difficult is the issue of access to those

data. Most researchers consider that they have a proprietary

right to the data from projects that they are in charge of;

yet some, or most, of these data may have been collected

by their predecessors. There is always an inclination to

hoard data until the opportunity arises to publish the information and, given the current pressures on researchers, this

is unlikely to change. However, the collection of another

year of data is often a reason that is used not to publish

data, and some balance is needed between the needs of the

researcher and the needs of the end-user communities. To

be effective, the data from long-term research experiments

need to be gathered into a relational database and, where

possible, access to this database needs to be available

through networks (both Intranet and Internet).

There may also be institutional barriers to the development of long-term research projects, even when research

funding is available. One issue is the availability of suitably

qualified personnel. During the formulation phase, the most

important person on the project team is the statistician, but

a distressing number of experiments are launched without

adequate statistical input. Newly-trained scientists may be

reluctant to embark on research that is unlikely to produce

publishable results for some time, and here, again, the

importance of achieving a balance between the generation

of short- and long-term results becomes important. Staffing

continuity is also important: although some staff turnover

27
is inevitable and may indeed be desirable during different

phases of a project, the abrupt departure of an entire project

team could negate years of data collection and associated

research.

INFORMATION NEEDS OF FOREST

STAKEHOLDERS 

It is difficult to judge the information needs of forest

stakeholders, just as it is often difficult to identify the

stakeholders. In most cases, there is a range of potential

stakeholders with an interest in the information. Identifying

those stakeholders can be particularly challenging, and

converting data into information that is useful to them is

even more so. Research that is valued within an academic

context is often of little relevance to those with an interest

in the research results. In some jurisdictions, effective 

communication between stakeholders and researchers has

enabled the development of research agendas that are relevant. However, there remains an inherent suspicion among

some academics that applied research is somehow less

worthwhile than “pure” research. Forest scientists need to

encourage a change in this view; they need to demonstrate

the value of applied research. One problem is the conflict

between the needs of those who are likely to use the results

and those who provide the funding for the research. Much

research funding is reactionary, reflecting the immediate

needs of government (or industry) to resolve an emerging

crisis or to justify a particular policy. As a result, the research

may be designed to provide results that support a particular

point of view, rather than addressing long-term, strategic

problems through the provision of balanced, scientifically

credible information.

A remarkable exception has been the U.S. National

Science Foundation, which has provided funding for the

Long-Term Ecological Research (LTER) sites (Gosz et al.

1999). The network of sites across the United States has

provided the foundation for long-term studies of ecosystem

processes, and has avoided many of the problems associated

with long-term research. The problems associated with data

handling and storage have been dealt with, and the program

has been extended beyond the United States (e.g., Barbosa

et al. 2004, Su et al. 2001). The sites have provided an important training ground for future natural resource scientists,

and the networking opportunities have resulted in strong

scientific teams.

The science behind the establishment of long-term experiments can be an impediment to the establishment of good

stakeholder relations. Stakeholders may not always be aware

of some of the ramifications of particular experimental

designs, just as scientists may not be aware of some of the

political, social or cultural implications of their work. Early

collaboration seems an essential part of developing a strong

working relationship between scientists and stakeholders,

and neither group should underestimate the time commitment

that this could involve. In forestry experiments, scientists

must generally work closely with forest managers: many

successful experiments arise out of the productive collaboration between scientists and forest managers. There are

costs involved for both parties, and unless both are willing

to meet these costs, the experiments are unlikely to be

successful.

It may be difficult for stakeholders to articulate their

needs for information: they do not always know what they

want. This position seems widespread in forestry. Bunnell

and Kremsater (2003) have argued that there is a greater

need for humility among forest policy makers, an argument

that must also be extended to forest scientists. A recognition by all of imperfect knowledge may be difficult, but it

is essential.

The lack of awareness of knowledge gaps reinforces the

need for extension agencies. However, such agencies must

move forward from the traditional university–private landowner relationship to include all aspects of research and to

extend to foresters in government as well as those in practice. This is particularly important where professional associations have no compulsory program of skills development

and continuing education, as in British Columbia.

IMPLEMENTING SUSTAINABLE 

FOREST MANAGEMENT

A key aspect to implementing sustainable forest management is converting information from long-term forest

experiments into knowledge that forest managers and policy

makers can use on a daily basis. Within the United States,

this is largely a function of the extension services for forest

managers and the USDA Forest Service for federal policy

makers. However, such services are relatively rare: Canada

has no direct equivalent of the extension services mandated

by the Morrill and Smith Lever Acts, although the gap in

western Canada at least is now being filled by the Forest

Research and Extension partnership (FORREX) http://www.

forrex.org). In the United States, the Forest Service has also

played a major role in making information available, with

the Pacific Northwest Research Station (http://www.fs.fed.

us/pnw/) leading the way. However, funding managers also

fail to consider the importance of extension, generally under

28
funding extension agencies. This seems to be because many

funding body advisory committees are made up of traditional scientists who think that the highest proportion of the

budget possible should be devoted to research. The problem

is exacerbated by those researchers who fail to budget adequately for extension. The result is that while the quality of

the research project may be excellent, the knowledge that

is generated fails to reach the people who can use it.

There is debate over the most effective extension techniques. Much depends on the nature of the target audience,

and it is increasingly apparent that multiple versions of the

same information will have to be prepared if the recipients

of that information comprise a range of different stakeholders. Most research scientists do not have the time or the

budget to do this, and many do not even go out with managers to explain and demonstrate the significance of their

results. This is a major shortcoming of some research projects and one of the reasons why some fail to achieve their

desired impact.

Although direct contact with managers on the ground is

often the most effective way to see information converted

into knowledge, there are experiments around the world

that it would be impossible for all managers to see. A way

to access the information being generated from these experiments is required. The International Union of Forest

Research Organizations (IUFRO) has been involved in the

development of an information system that would facilitate

access to such information, the Global Forest Information

System (GFIS). A prototype of this was launched at the

World Forestry Congress in 2003 (http://www.gfis.net ), and

this year (2004) it has been undergoing an extensive overhaul. With over 60 contributing organizations, GFIS is

growing steadily. It is currently concentrating on facilitating

access to the “grey literature,” but a special project includes

developing a major new educational resource. The system

has been set up in such a way that it could act as a search

engine for long-term data sets and the information associated

with these. 

The transfer of information to policy makers is more

complex, and it is unfortunate that in general, many policy

makers have not been receptive to scientific information.

Although jurisdictions such as British Columbia claim to

have science-based forest management, it is sometimes difficult to see that science. IUFRO has been looking into this

problem, having created a task force to address the issue.

The task force held its fourth meeting in June 2004, where

the results from a number of regional workshops were synthesized, and an attempt was made to identify the critical

factors leading to the successful transfer of scientific information to policy makers. Improved methods of interaction

between policy makers and scientists are clearly required,

and the IUFRO World Congress (http://www.iufro2005.com),

to be held in Brisbane in August 2005, is placing special

emphasis on this.

More effective interaction between scientists and managers will require several changes in the way that science 

is practiced. Sayer and Campbell (2004) propose that seven

major changes will be required to integrate science with

sustainability (table 1), but it is quite clear that the majority

of the forest research community is not yet ready to make

these changes. Acknowledging the complexity of natural

systems is essential, although most science is reductionist

in its approach. There is always pressure to provide a “simple explanation,” but there is a marked difference between

providing a simple explanation and providing an explanation simply. Most stakeholders are unfamiliar with scientific

jargon, and explanations that are jargon-free are essential.

The need for action research has been recognized by

many foresters. Although this can be interpreted several

ways, the adoption of an active adaptive management

approach is critical. In this, researchers and forest managers

work together to design an experimental approach to new

management practices, with adequate controls being used

to ensure that any observed impact of a management action

can be ascribed to that action. The approach involves a substantial monitoring element which is not only often difficult

29

Table 1—Seven actions needed to ensure better uptake of knowledgea

• Acknowledge and analyze the complexity of natural resource systems

• Use action research—become actors in the system

• Consider effects at higher and lower scales

• Use models to build understanding and as negotiating tools

• Be realistic about potential for dissemination and uptake

• Use performance indicators for learning and adaptation

• Break down the barriers between science and resource users

a Sayer and Campbell 2004
to fund, but may also be considered as so routine that

researchers should not be involved. However, it is widely

recognized that projects that practice adaptive management

are able to retain their relevance to policy makers better

than projects that do not (Guldin 2003).

Considering effects across scales, both higher and

lower, is important for long-term experiments. A major

weakness of many long-term experiments is that they are

often used for research for which they were not designed.

Responses are scale-dependent (Innes 1998), and what may

be appropriate for one scale may not be appropriate at

another scale. There has been a tendency in many long-term

experiments to try to use the facility to conduct investigations for which they were designed. For example, censuses

of birds are commonly conducted on long-term experimental plots, but many treatment areas are often too small

to provide reliable estimates of their use by birds.

The use of models provides the opportunity to demonstrate the likely outcomes of particular scenarios. Models

provide an indication of the likely long-term outcomes of

particular actions and can “look” into the future in a way

that is impossible from observational studies. This is examined in greater detail in the following section. 

Many of the difficulties associated with disseminating

research results and their subsequent uptake can be related

to the methods chosen to communicate the results. There

has been a presumption that the most effective means of

communication is through the written word. Although this

may be true for some audiences, it is not so for all. For

example, some groups may have a tradition of oral communication, and this will likely be the most effective way

of communicating with them. Even if information is successfully transmitted, there may be no application of that

knowledge. A complex suite of factors influence this, but

they are beyond the scope of this paper.

Finally, there are numerous institutional barriers between

scientists and stakeholders. These range from physical separation to several factors that restrict the ability of scientists

to interact with resource users. For example, the reward

structures for scientists are often based more on their ability

to publish in top scientific journals than on their ability to

interact with forest managers and other stakeholders. This

can be a significant impediment; not only are scientists discouraged from spending time interacting with forest managers, but they are also discouraged from publishing their

work in outlets likely to be seen by forest managers. Again,

this is where extension specialists have a role to play. 

EVALUATING AND COMMUNICATING

THE RANGE OF MANAGEMENT

OPTIONS

Evaluating and communicating the range of management

options will be difficult. In some areas, such as British

Columbia, significant developments have occurred in forest

modeling, and ecological growth models have been linked

to habitat models and harvest scheduling models, with the

results being visualized through computer graphics. This

will undoubtedly help stakeholders see the potential impacts

of particular choices, particularly those involving trade-offs

between different values. Mapping tools are also becoming

increasingly sophisticated and may be more familiar to

managers. However, as with the publication of results, it

seems likely that different techniques will need to be developed for different audiences. Visualization is being increasingly used in education (Fabrika 2003), although there are

ongoing debates over the relative advantages and disadvantages of realistic vs. stylized pictures. 

Just as there increasing possibilities of visualization,

more technology is available that could help stakeholders

decide between different options. Adoption of these technologies has been relatively slow, and many of the techniques have been derived from outside the traditional field

of forestry. The difficulties associated with the implementation of decision support tools reflects the lack of training

that many foresters and forest scientists have had in the

“social” aspects of forestry. Interest is now gaining in this

area, and it is likely that they will be increasingly applied

to the scenarios being produced as part of long-term forest

experiments.

CONCLUSIONS

Long-term experiments are invaluable to forestry, but

transforming the information generated by them into knowledge that can be used to improve forest management practices is critical. There are many barriers to this, and most

managers of long-term forest experiments are devoting so

much time to the maintenance of funding for their work

that there is little opportunity to address such issues as

extension and uptake. This is creating a “vicious circle,” as

the funding is dependent on the managers being able to

demonstrate the value of their experiments. 

The conversion of information to knowledge and the

dissemination of that knowledge to those who can best use

it is a critical stage of any long-term forest research project.

30
There is a need to better plan for this and to ensure that it

becomes as an integral a part of project planning as the

experimental design. Whether this can be achieved in the

short-term remains to be seen.

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for Swiss forests. In: Beniston, M., ed. Mountain environments in changing climates. London: Routledge:

281-298.

Innes, J.L. 1995. Theoretical and practical criteria for 

the selection of ecosystem monitoring plots in Swiss

forests. Environmental Monitoring and Assessment. 

36: 271-294.

Innes, J.L. 1998. Measuring environmental change. In: 

Peterson, D.L.; Parker, T., eds. Scale issues in ecology.

Columbia University Press: 429-457.

Innes, J.L. 2003. The incorporation of research into 

attempts to improve forest policy in British Columbia.

Forest Policy and Economics. 5: 349-360.

Kochummen, K.M.; LaFrankie, J.V., Jr.; Manokaran, N. 

1990. Floristic composition of Pasoh Forest Reserve, a

lowland rain forest in Peninsular Malaysia. Journal of

Tropical Forest Science. 3: 1-13.

Offerman, H.L.; Dale, V.H.; Pearson, S.M.; Bierregaard, 

R.O. Jr.; O’Neill, R.V. 1995. Effects of forest fragmentation on Neotropical fauna: current research and data

availability. Environmental Reviews. 3: 191-211.

Sayer, J.; Campbell, B. 2004. The science of sustainable 

development. Cambridge, UK: Cambridge University

Press. 268 p.

Schütz, J.P. 1997. Sylviculture 2. La gestion des forêts 

irrégulières et mélanges. Lausanne, Switzerland:

Presses Polytechniques et Universitaires Romandes.

Su, W.; Brown, M.J.; Mackey, B. 2001. Agent-based 

dynamic modeling of forest ecosystems at the Warra

LTER site. Tasforests. 13: 129-140.

31
Leslie Brodie and Tim Harrington (both from the Pacific Northwest Research Station) present findings on stand damage and windthrow following partial

harvests on the Washington State Capitol Forest. Photo by Charley Peterson
REGIONAL EXPERIMENTS 
Photo by Tom Iraci
1 Assistant Professor, and 2 Associate Professor in the Department of Forest Science, 321 Richardson Hall, Oregon State University, Corvallis, OR 97331,

USA. Email for corresponding author: lisa.ganio@orst.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Design Challenges in Large-Scale 

Management Experiments

Lisa M. Ganio1 and Klaus J. Puettmann2

INTRODUCTION

Recent interest in ecosystem response to management

activities has led to the implementation of large-scale management experiments (LSMEs) (for examples, see Monserud

2002). These studies are designed to address management

and policy issues at the scale at which management occurs,

practically eliminating the challenge to scale up research

results to operational activities. However, integrating the

work of multiple investigators, each possibly working on

multiple objectives, in a single study creates challenges 

not encountered in traditional research studies (Ganio and

Puettmann, n.d.). These challenges, in conjunction with the

long-term, large-scale nature of these experiments, have to

be addressed in the experimental design and setup. Specific

issues include ranking and coordinating research objectives,

scopes of interest, choice of response variables, replication

and subsampling, treatment definitions, and measurement

logistics. It is important to recognize that these components

are linked; they cannot be viewed or discussed in isolation,

ABSTRACT

Large-scale management experiments (LSMEs) are implemented at the scale at which management occurs. These studies

are typically longer term and include multiple objectives at multiple scales that cover a spectrum of natural resources topics.

Designing a study that effectively incorporates these features can be challenging. The initial steps in the design process are

prioritizing multiple objectives and identifying primary, secondary and tertiary levels. This hierarchy is used to allocate

resources throughout the design process. Each objective implies an associated scope of inference, which in turn is associated

with a specific definition of replication. Discussing and coordinating scopes of interest and identifying levels of replication

associated with each one are important steps in planning a study. The large spatial and temporal scales in an LSME are a

source of large spatial and temporal variation. In an effort to control variation, investigators may initiate changes without

considering the effects on the hierarchy of objectives. A structure for acknowledging and planning for these large sources 

of variation in the design phase is discussed. 

KEYWORDS: Large-scale management experiments, study design, multiple objectives.

35

and changes to any one of the components will likely affect

the others (Manly 1992). 

We propose that dealing with a diverse set of objectives

in a single experiment, especially in LSMEs, highlights the

importance of proper experimental design; this is necessary

to accommodate planning and implementation issues not

present in single-objective studies. Experimental approaches

used in various disciplines need to be accommodated when

multiple objectives (each with its own optimal approach)

are combined in a single experiment. This paper discusses

study design concepts in this light and highlights statistical

and logistical issues that need to be considered in the design

of LSMEs. 

MULTIPLE OBJECTIVES 

AND SCOPES OF INFERENCE

The first steps in planning LSMEs are defining and 

prioritizing research objectives. Generally, the primary
objective of LSMEs is to document and compare ecosystem response to large-scale management practices over

large extents of space and time, e.g., effects of partial overstory removal on bird habitat. But this primary objective

can be manifested in multiple secondary objectives that

need to be determined and agreed upon. Secondary objectives may include studying effects of large-scale treatments

on smaller scaled processes, such as conifer germination or

seedling growth as a function of degree of overstory removal.

Tertiary objectives may include documenting effects of

smaller scaled secondary treatments embedded in the largescale treatments, such as seedling response to weed control

under different overstory densities. Prioritizing multiple

objectives becomes the basis for making choices among

alternative study design components throughout the experiment.

Even though LSMEs cover large areas, the questions 

of where and under which conditions results can be used to

guide management decisions need to be considered during

the design phase of a study (Ganio and Puettmann, n.d.).

The scope of inference represents the set of situations to

which the results of the current study can be generalized.

Replicate units represent the range of variation present in

this scope of interest (Hurlbert 1984). As a result of multiple

objectives, an LSME is likely to have scopes of inference

at multiple scales and thus require replication at multiple

scales. A detailed discussion of potential scopes and their

associated sources of replication for the various objectives

can identify realistic and unrealistic goals. For example,

long-term growth response of residual trees to partial overstory removal is not very sensitive to the climate conditions

in the spring after the removal. Most foresters would feel

comfortable basing management decisions on results from

such studies regardless of expected weather patterns. On

the other hand, germination of seed may be quite sensitive,

and the results from studies in which the overstory treatments were all applied in a single year should only be used

to predict germination under similar climatic conditions.

Discussions about scopes of inference among all researchers

during the planning processes can clarify the extent to which

conclusions can be generalized and elucidate necessary

modifications of the study design. 

Multiple objectives typically cannot be addressed with

the same precision in a single study. The prioritization of

objectives helps determine how to allocate resources or

replications for the study. In an ideal situation, the primary

objective requires the most replication so that secondary or

tertiary objectives are also adequately replicated. In cases

where secondary or tertiary objectives require more replication than the primary objective, however, the experimental

design has to be adjusted. For example, to investigate effects

of weed control on seedling growth under dense overstory

conditions in detail, additional replications could be added

in similar, neighboring stands.

The following example demonstrates the interrelationships among the ideas discussed above. Suppose that the

large-scale objective is to compare thinning practices on

overstory development over 25 years. Six 85-ha units are

selected to represent western Oregon and Washington (the

scope of inference). A secondary objective is to assess the

thinning practices on mushroom production, and a tertiary

objective is to compare seedling response to a variety of

weed control practices. Mushroom production is highly

variable at small spatial scales and from year to year. On

the surface this may seem a straightforward study, but a

number of specific questions have to be addressed: Will 

the results from six 85-ha units scattered over two states be

able to represent typical mushroom production in western

Oregon and Washington in any one year? How might variation among the large-scale units within one year compare

to environmentally induced variation at one site from year

to year? Will six replicates of mushroom production achieve

a level of precision sufficient to detect changes among

large-scale thinning practices? Should the scope of inference for the secondary objective be restricted to a narrower

set of conditions represented in one large-scale unit while

many replications on a smaller scale are used to quantify

trends over time? If so, the small replications do not constitute true replications of large-scale thinning. Should investigators look for areas outside this LSME that can be used

as auxiliary replicates? These questions highlight how the

hierarchy of objectives, the spatial and temporal scopes of

inference and replications are all interrelated. Although

answers to some of these questions may be unknown, an

understanding of these issues is necessary to define the

proper study design. In these instances, expert opinion and

results from similar studies may be the only sources of

information available for consideration. 

GENERAL SPATIAL AND 

TEMPORAL CONSIDERATIONS

Scale can be defined as the extent over which a phenomenon exists and as the resolution at which it exists

(Dungan et al. 2002). A scale is associated independently

with the process being studied (e.g. the treatment), the

observation process, and the analysis. When observation

scales (e.g., plot sizes) and analysis scales are not explicitly

coordinated, results may not directly address the research

question as planned (Dungan et al. 2002). Estimated treatment differences and associated estimates of variation

36
change as observation scales change. Therefore, the design

process should include an assessment of the appropriate

precision and scale of the observation process (Skalski and

Robson 1992). If results of LSMEs are to be compared to

other studies, then assessment of the spatial and temporal

scales is prudent. 

Secondary treatments may be embedded within the

large-scale silvicultural treatments in a split plot experimental design. A common example is the comparison of

different tree species when planted under thinned overstories. However, embedded treatments may interact in

unintended ways with large-scale treatments in time or

space. For example, the underplanted seedlings may eventually influence wildlife habitat to the extent that the original large-scale objective (to investigate effects of thinning

on wildlife habitat) is compromised. Future problems can

be avoided and alternatives suggested if this possibility is

considered during the design phase. Embedded treatments

do not increase the replication of the large-scale treatment,

and care should be taken to identify and avoid pseudoreplication (Hurlbert 1984, Monserud 2002). Scopes of inference for embedded treatments are generally at a smaller scale

than scopes for large-scale treatments, and this needs to be

reflected in decisions about adequate and appropriate replications for embedded treatments. The issues associated with

embedded treatments are complex and discussion of potential long-term consequences among the various researchers

in an LSME can identify potential pitfalls that can be

addressed in the design phase. 

Each research objective has an associated temporal

extent (in LSMEs, many of them are long-term), and a

timeline along which ecosystem responses are measured.

Careful evaluation and coordination of timelines and

extents are important for LSMEs when treatment applications or measurements may not occur at the same time for

all treatments or sites. An understanding of the temporal

variability of response variables is required to make decisions about treatment timing. Experience has shown that

treatment applications to large-scale experimental units

cannot be always accomplished in the same season or even

year (e.g., in the Young Stand Thinning and Diversity Study

(Hunter 2001)); therefore seasonal or inter-annual effects

may be exhibited differentially on experimental units and

objectives. A harvesting delay of a few months may not

unduly impact the assessment of long-term tree growth

response. But it may be very influential in an assessment

of natural regeneration, especially if portions of the unit

were harvested prior to seed maturity and other portions

were harvested after seeds had dispersed. Effects of measuring experimental units in different seasons or years need

to be carefully assessed in the design phase. If treatments

were applied in different years, and yearly variation is part

of the scope of inference, then measuring replicates of each

treatment in different years (e.g., tree growth response 3 years

after treatments) is necessary (Monserud 2002). However,

measuring different treatments in different calendar years

confounds the treatment with yearly variation for some

factors (i.e., seed rain or germination) such that the ability

to make comparisons is compromised. For these factors, if

the goal is to compare treatments in the absence of yearly

variation, measuring each replicate of each treatment in the

same calendar year is crucial. In the example above, initial

treatment definitions may need to be modified to reflect that

temporal effects are confounded with treatments. Because

an important aspect of LSMEs is the integration of various

study components, coordinating treatment timelines is critical to ensure that all necessary response variables are representing effects at the same points in time. Using comparable

definitions and resolutions of a response variable over time

is important for the same reasons. 

SPATIAL AND TEMPORAL EFFECTS 

ON TREATMENT DEFINITIONS

In long-term experiments, treatments may consist of 

an initial large-scale application followed by additional

manipulations conducted in later years. These follow-up

manipulations should be considered carefully. Ecosystem

developments after multiple manipulations cannot be attributed solely to the initial application; they are a function of

the entire set of manipulations. The decision to use additional manipulations brings up a variety of complex issues.

For example, if the initial application resulted in different

ecosystem responses in each replicate plot and follow-up

manipulations are implemented at the same point in time,

then follow-up treatments are applied to different “initial”

conditions. Additional variation among replicates may result,

making the detection of treatment effects more difficult.

Alternatively, if follow-up manipulations are applied to

replicate plots within one treatment when specific conditions

within those replicates are met, follow-up treatments may

not be applied at the same time for different treatments. In

this case, treatments may incorporate different inter-annual

or seasonal effects that are confounded with treatment effects.

During the planning phase of LSMEs, the advantages and

disadvantages of these approaches should be clearly laid

out and referenced against the hierarchy of objectives before

choices are made. These issues may have to be addressed

repeatedly throughout the life of a study as treatment and

environmental effects may interact over time and space in

unpredictable ways. For example, unpredicted growth or

mortality of particular species, unintended browsing by elk

37
or deer, or catastrophic environmental conditions may result

in unanticipated conditions within experimental sites. These

may prompt researchers to consider unplanned manipulations on the treatment units. Without proper planning these

manipulations may change the original scope of inference

in unintended ways or inadvertently modify an objective. 

Suppose that an understory grass, such as Brachypodium

sylvaticum, invades some, but not all replicate plots of

some treatments in an LSME designed to compare one-time

thinning practices. Researchers are reluctant to drop the plots

from they study and reduce the level of replication, so they

consider removing the invaders. However, this manipulation is likely to make more resources available to the overstory trees in the treated plots. A logical choice may be to

consider analogous manipulations in the remaining unaffected plots. But if implemented, the plots will no longer

represent conditions as originally envisioned. The objective

has changed from the evaluation of the single-thinning to

thinning-plus-follow-up-removal-of-competition and the

scope will be expanded to stands with invasive understory

grasses. 

SAMPLING WITHIN TREATMENT UNITS

Although treatments are applied to large scales in LSMEs,

the experimental unit that receives a large-scale treatment

is generally not measured in its entirety; measurements are

commonly made on subplots. It is important to note that

the role of each subplot is to represent the large-scale plot,

analogous to the role of treatment replicates for a treatment.

Also, large-scale units are likely to be measured multiple

times, perhaps by multiple researchers. During the design

phase, coordinating criteria for representative plot layouts

and proper measurement standards helps ensure that different responses at the same time and the same responses at

different times are comparable. 

Often simple random sampling within an experimental

unit will represent the replicate adequately. This implies

that subplots for measurements are selected from the set of

all possible subplots within the experimental unit with a

known and equal probability of selection. Occasionally there

is a concern that a lack of subplots representing rare conditions within large-scale units will lead to biased response

measures and underestimate variation. In these cases, the

temptation exists to purposely place subplots in rare or

unusual areas to ensure that they are sampled. This method

results in biased estimates of plot averages because the rare

conditions are over-sampled. An alternative sampling method

to account for differing proportions of important conditions,

such as stratified random sampling, can be used as long as

the proportions of each condition are known. In these cases,

it is necessary to calculate weighted averages of the subplot

responses to create unbiased estimates for the large-scale

unit (Thompson 2002). 

CONCLUSIONS

We conclude that coordination and discussion among 

all participants during the design phase and implementation

of LSMEs is a pervasive theme. Explicit lists of objectives,

response variables, scales of inference, measurements, timetables for treatment application and measurements should

be drafted, frankly discussed, and evaluated. We suggest

that developing a hierarchy of objectives that is agreed

upon by all participants is crucial for success of LSMEs.

This ensures that logistical and conceptual constraints and

opportunities are understood. Open and forthright discussions of pros and cons, hypothetical outcomes, and potential

pitfalls can go a long way toward foreseeing and producing

an optimal study. Future visioning can highlight the importance of particular choices as well as suggest potential

solutions for possible setbacks. Thorough and thoughtful

planning is paramount.

REFERENCES

Dungan, J.L.; Perry, J.N.; Dale, M.R.T.; Legendre, P.; 

Citron-Pousty S.; Fortin M.J.; Jakomulska A.; Miriti

M.; Rosenberg M.S. 2002. A balanced view of scale in

spatial statistical analysis. Ecography. 25: 626-640.

Ganio, L.M; Puettmann K. [N.d.]. Large-scale forestry 

experiments and the hierarchy of objectives. Manuscript

in preparation. On file with: L. Ganio, Department of

Forest Science, 321 Richardson Hall, Oregon State

University, Corvallis, OR 97331.

Hunter, M.G. 2001. Management in young forests. Cascade 

Center for Ecosystem Management. Communique No.

3. www.fsl.orst.edu/ccem/pdf/Comque3.pdf (November

11, 2004).

Hurlbert, S.H. 1984. Pseudoreplication and the design of 

ecological field experiments. Ecological Monographs.

54: 187-211.

Manly, B.F.J. 1992. The design and analysis of research 

studies. New York: Cambridge University Press. 353 p.

38
Monserud, R. 2002. Large-scale management experiments 

in the moist maritime forests of the Pacific Northwest.

Landscape and Urban Planning. 59: 159-180.

Skalski, J.R.; Robson D.S. 1992. Techniques for wildlife 

investigations, design and analysis of capture data. San

Diego, CA: Academic Press Inc. 237 p.

Thompson, S.K. 2002. Sampling. New York: John Wiley 

& Sons. 400 p.

39
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1 Curtis Hutchins Professor of Silviculture, Department of Forest Ecosystem Sciences, University of Maine, Orono, ME 07769-5755, USA. 

Email: Seymour@apollo.umenfa.maine.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Integrating Natural Disturbance Parameters into 

Conventional Silvicultural Systems: Experience From the Acadian

Forest of Northeastern North America

Robert S. Seymour1

INTRODUCTION

Foresters in northeastern North America who seek to practice ecologically-based silviculture face many challenges,

ranging from incomplete knowledge of ecosystem processes

to resisting financial pressures that lead to unsustainable

harvesting. This paper attempts to blend our rapidly advancing knowledge of disturbance ecology with existing silvicultural knowledge and experience. My goal is to illustrate

how two key attributes of natural disturbances—recurrence

interval and patch size—can be readily accommodated by

contemporary modifications to a traditional, though little

used, silvicultural system.

DISTURBANCE ECOLOGY

OF NORTHEASTERN FORESTS

Large-scale commercial forestry in northeastern North

America is centered in the northern New England States

ABSTRACT

With rare exceptions, the presettlement Acadian forest of northeastern North America was driven by gap dynamics; true

stand replacing disturbances were quite uncommon, with recurrence intervals of many thousands of years. After centuries 

of human exploitation, stand age structures have become simplified, and commercial timber rotations are a fraction (15 to

40 percent) of the lifespan of the common late-successional tree species. Adapting silvicultural systems to strengthen their

ecological foundation thus confronts the challenge of converting single- or two-cohort stands to more complex structures

via various combinations of regeneration and retention. This paper reviews the region’s research and management experience with two fundamentally different approaches to this challenge: regeneration in distinct, relatively small gaps vs. uniform stand-wide regeneration under different levels of overwood reserve trees. A hybrid system is described that combines

the proven benefits of shelterwood with the restoration advantages of group selection; in American terminology, the system

is an irregular group shelterwood with reserves, similar to the German Femelschlag in which gaps are created and gradually

expanded over several cutting cycles. Two illustrations of how this (or any) silvicultural system can be benchmarked against

natural stand dynamics are provided.

KEYWORDS: Ecological forestry, restoration silviculture, red spruce, shelterwood, selection, conversion, Femelschlag.

41

(Maine, New Hampshire, Vermont) and the Canadian

Maritimes (mainly New Brunswick and Nova Scotia). Unlike

southern and central New England, much of this region was

never settled or cleared for agriculture, and thus remains as

a large, virtually unbroken block of contiguous forest stretching from the eastern coast of New Brunswick through the

Adirondack Mountains of New York. Two major forest types

predominate here, each with many subtypes and local variants in response to edaphic and climatic variation: the socalled “spruce-fir” forest, that contains assemblages of red

spruce (Picea rubens Sarg.) and balsam fir (Abies balsamea

(L.) Mill.), and the “northern hardwood forest,” dominated

historically by sugar maple (Acer saccharum Marsh.)

American beech (Fagus grandifolia Ehrh.), and yellow birch

(Betula alleghaniensis Britton). Common associates include

red maple (Acer rubrum L.), eastern hemlock (Tsuga

canadensis (L.) Carr.), eastern white pine (Pinus strobus

L.), and northern white-cedar (Thuja occidentalis L.).
These species can live for 300 years or more, and most

are quite shade-tolerant, typically reproducing by advance

regeneration that may exist for many decades in the understory before canopy accession (Seymour 1995). Although

they can grow and develop well in single-cohort stands and

are commonly managed this way today, such structures

were uncommon before human exploitation began in the

18th century. Owing to abundant precipitation throughout

the growing season, stand-replacing fires were very infrequent, as were stand-replacing windstorms, with estimated

return intervals of many centuries to millennia (Lorimer

and White 2003). As a consequence, gap dynamics were

the most common natural disturbance, which led naturally

to a forest structure dominated by late-successional, multiaged stands (Seymour et al. 2002).

HISTORY OF HUMAN EXPLOITATION

AND MANAGEMENT

Centuries of human exploitation for forest products, first

for large sawlogs and later (ca. 1900) for smaller-diameter

pulpwood, have radically changed the forest structure.

Remnants of the primary, old-growth forest are quite rare,

and many, such as the Big Reed Reserve in northern Maine

owned by The Nature Conservancy, have been reserved

from commercial logging and studied intensively by ecologists (e.g., Fraver 2004). The typical commercial forest

landscape is dominated by stands that are younger and more

even-aged than during presettlement. Changes in species

composition have been less dramatic; nevertheless, typical

stand compositions have shifted from the slower-growing,

late-successional species to those that are favored by frequent harvest disturbance, such as red maple, paper birch

(Betula papyrifera Marsh.), aspen (Populus spp.), and balsam fir. It is not uncommon to find legacies of the presettlement forest remaining in many stands, such as large cull

trees and small, long-suppressed saplings of late-successional species absent from the overstory, but these are usually a byproduct of their low commercial value, not a

conscious act of retention.

When I arrived in Maine in the late 1970s, the landscape was dominated by well stocked, even-aged spruce-fir

stands that, I was told, had originated after the devastating

spruce budworm (Choristoneura fumiferana Clem.) outbreak ca. 1913-19. Careful reconstructions of these stands

using records and increment cores, coupled with review of

early descriptions of the original forest and early harvesting

(e.g., Cary 1894, Hosmer 1902) invariably revealed that

these even-aged stands had originated by some heavy, often

repeated, timber harvests ca. 1880-1925. Only pure fir stands

(which were originally neither common nor extensive)

seemed to have a unique budworm origin (Seymour 1992).

Many of these dense, even-aged, and ecologically immature spruce-fir stands were again clearcut during the 1980s,

partly in response to the budworm outbreak of that time.

Many industrial landowners treated large areas of the regenerating third-growth forest with herbicide release and precommercial thinning, with little attempt to favor red spruce

over fir. Now, as these stands approach commercial size,

there are large areas of 25-year-old, spaced, nearly pure fir

stands, where 150 years before stood old-growth red spruceyellow birch forests with fir as a minor component.

SILVICULTURE FOR ECOLOGICAL

RESTORATION

Challenges

Any serious attempt at ecological forestry (see Seymour

and Hunter 1999) in this region must confront the simplified age structures and altered compositions of repeatedly

harvested stands using a patient restoration approach. The

goal of such a restoration strategy is to re-create a forest

dominated by diverse multi-aged stands, with at least some

having a late-successional component that is deficient in

the commercial forest. In the Acadian region, this problem

is arguably more difficult than in regions like the Pacific

Northwest where the natural stand-development patterns

follow a single-cohort model, and the challenge is merely

softening clearcuts with structural retention measures. In

the Northeast, leaving scattered islands or reserve trees in

clearcuts or uniform shelterwoods of >10 ha, although

valuable in some respects, often fails to address the more

fundamental mismatch of even-aged silviculture with natural processes.

During the past decade or so as ecological forestry concepts have entered mainstream thinking, I believe that most

academics and scientists share a common view about the

difference of our present forest from that of presettlement.

Practitioners are generally more skeptical, not necessary of

the underlying science, but of its relevance to their day-today existence. Further, just as the consciousness of ecological forestry is being raised, there has been a wholesale

sell-off of large parcels formerly held by forest industry to

timberland investors whose time horizons are much shorter

and who expect double-digit returns. Relative to the goals

of restoration and ecological sustainability, much of this

former industrial forest just needs a “rest,” yet it is faced

with ever-increasing pressure to generate income from the

remaining growing stock. My own experience suggests that

stewards of public forests, especially those under management by state forestry agencies in the United States, have

42
resisted such pressures and tend to be more receptive to

restoration silviculture than many privately owned forests.

Possible Restoration Pathways

Conceptually, the challenge of converting even-aged

stand structures to more complex ones is straightforward: 

a series of regular harvest entries, spaced out over a relatively long conversion period (e.g., 50 to 100 years), each

regenerating only a relatively small portion of the stand. Of

course, this is easier said than done, especially if the stand

is already understocked from prior harvests. Nyland (2003)

discusses two different ways to approach this problem: uniformly distributed reductions in overstory density at each

cutting versus creation of distinct canopy gaps. As diagrammed by Nyland, the first option begins as a light, uniform

shelterwood establishment cutting and ends (after 5 cutting

cycles) as single-tree selection. The second option can be

categorized as patch or group selection throughout. Both

assume equal cutting cycles and an age-balanced stand at

the end of the conversion period.

The shelterwood method is commonly recommended in

this region for regenerating spruce-fir, northern hardwood,

and white pine-red oak forests (Hannah 1988, Seymour 1995)

and is viewed by many foresters as the best way to restore

degraded stands to higher timber productivity. Although

sometimes considered an alternative to even-aged management because it involves “partial cutting” at the establishment stage, shelterwood management is at best a two-aged

system depending on the density of reserve trees, if any. As

practiced by most private owners, establishment cuttings

are uniformly applied and fairly heavy (40- to 60-percent

removals); furthermore, reserve trees left after overstory

removal are not numerous (generally <10 percent of the

original stocking) and thus do not significantly affect the

dominant younger cohort. So, although uniform shelterwoods may be an effective method to improve species composition and provide economic returns, they fail as a system

for restoring multi-aged stand structures. 

Group selection cutting is much less common than shelterwood, but is gaining popularity in formerly high-graded

northern hardwood forests with an overabundance of beech

regeneration. The improved light environment of even small

gaps gives sugar maple and the birches an advantage over

the vegetative beech reproduction, as long as advance regeneration of maple is established and birch seed reaches the disturbed gaps (Seymour 1995). Group selection is quite

uncommon in spruce-fir forests; examples are limited to

some public ownerships and small private woodlots. Although

preferable to shelterwood for ecological restoration, group

selection cutting has several drawbacks. If the matrix

between groups is not treated, the overall harvest can be

very light and thus problematic economically. Not treating

the matrix, however, risks losing volumes of valuable but

short-lived species, such as balsam fir, paper birch, and

aspen, that might not survive until the next entry.

Principles and Specifics

To convert uniform stands to more irregular, multi-aged

structures, one must consciously regenerate a portion of 

the stand at each entry while keeping the canopy of the 

surrounding matrix relatively intact and thus, unregenerated.

A comprehensive review of natural disturbance rates in this

region (Seymour et al. 2002, fig. 1) suggests that the area

regenerated should average about 1 percent per year, equivalent to a 100-year return interval. Assuming the goal is a

balanced within-stand age structure at the end of the conversion period, one simply multiplies the annual disturbance rate by the cutting cycle, just as one would do in a

forest of even-aged stands under area regulation (Nyland

1996). Adopting a cutting cycle of 20 years thus would dictate that each entry regenerate 20 x 1% = 20% of the stand

at each entry. Furthermore, regeneration should occur in

small gaps (under 0.1 ha) in order to remain within the

bounds of natural disturbance parameters (Seymour et al.

2002). Finally, to restore late-successional characteristics,

reserve trees must be retained in the gaps as they are regenerated; otherwise, there will obviously be no trees over age

100 when the conversion is complete. Ideally, reserve trees

are retained permanently and should consist primarily of

long-lived species from the main canopy. As they grow to

ecological maturity and eventually die, they will restore an

important late-successional structural component that is

typically absent from managed forests; they will function

as biological legacies (Franklin et al. 1997, Seymour and

Hunter 1999) and replenish the pool of large, woody material on the forest floor.

I believe that the guiding principle of such a silvicultural

system should be a stand structure based on area, not tree

size. Such a guide takes the form of a within-stand age

structure, rather than a tree size structure such as the negative exponential diameter distribution commonly associated

with balanced single-tree selection cutting (O’Hara 1996,

Seymour and Kenefic 1998, Smith et al. 1997). Specifically,

an area-based structure defines what percentage of the stand

is regenerated at each entry, along with a distribution of

patch (gap) sizes that comprises this area. An area structure

requires the forester to consider the regeneration process

explicitly at each entry, and thus avoids the historical pitfalls

of size-based, multi-aged systems that did not lead to adequate ingrowth of the desired species and were thus abandoned throughout North America during the 1950s in favor

43
44

of single-cohort systems (Curtis 1998; Seymour, in press;

Smith 1962).

Uniform vs. Gap-oriented Spatial Patterns

Relative to the goal of restoring age diversity, I believe

that Nyland’s (2003) first option, repeated uniform cuttings,

is not practical in our region and, arguably, does not work

ecologically. First, Acadian forests tend to develop dense

understories of advance regeneration under even light canopy

disturbances; hence the appeal of the simple uniform shelterwood method for production systems based on natural

regeneration. After a uniform cutting to 60-percent relative

density as recommended by Nyland (2003), the understory

will invariably fill up with tolerant advance growth. Further,

light uniform removals from the overstory serve only to

release this regeneration, not establish new cohorts as

required. In effect, the understory quickly reaches a stemexclusion condition (Oliver and Larson 1996), and the stand

never contains more than two cohorts. At best, a third cohort

might establish after the final overstory removal in areas

disturbed by harvesting equipment, but this is a common

feature of all systems. For conversion systems to work over

time, the dominant matrix must be kept at sufficient density

to prevent regeneration over most of the stand at a given

time; regeneration should occur only in defined gaps created

at each entry.

Another important drawback of uniform patterns is the

fact that the light cuttings required for true restoration, typically no more than 10- to 20-percent removals, are quite

impractical operationally if distributed evenly throughout

the stand. Concentrating such light entries, as done in gaporiented systems, promotes harvesting efficiency and costs

should be little more than for clearcutting if haul roads are

in place. Gap systems also allow other silvicultural treatments (e.g., enrichment planting to restore species, early

stand tending) to be conducted efficiently.

A Hybrid Silvicultural System: 

The Acadian Femelschlag

In 1994, a team of forest scientists and wildlife ecologists from the University of Maine faculty set out to design

a long-term experiment in ecological forestry known as the

Forest Ecosystem Research Program (FERP). This program

Figure 1—Evaluating the natural disturbance comparability of two gap-oriented silvicultural systems, using the reference metric from

Seymour et al. (2002).
45

would complement the existing, conventional silvicultural

systems on the Penobscot Experimental Forest maintained

by the USDA Forest Service Northeastern Research Station

since 1950 (Sendak et al. 2003). We based our silvicultural

systems on the disturbance rates, patterns, and structural

features of natural forests as best we understood them. One

system chosen was a traditional light group-selection cutting that removed 10 percent of the stand in small gaps on

a 10-year cutting cycle while retaining 30 percent of the

initial growing stock within the gaps as permanent reserve

trees. Although such a system arguably mimics natural

dynamics closely, the overall harvest rate is so light that is

was difficult to carry out logistically and economically. 

In an attempt to formulate a more operationally feasible

system without sacrificing its ecological basis, we devised

a hybrid between group selection and uniform shelterwood.

The key concept is to apply the well-known principles of

shelterwood regeneration in a patch-wise fashion within the

stand, rather than uniformly throughout, leaving reserve

trees in the groups after they are fully regenerated. Instead

of stand age structure changing temporarily as in a uniform

shelterwood, group shelterwood systems vary spatially, and

at times contain all stages of the shelterwood sequence:

unregenerated matrix awaiting treatment, two-storied patches

following establishment cutting, and free-to-grow sapling

regeneration after removal of the overstory except scattered

reserves. In order to make harvesting as efficient as possible

and to retain some intolerant species in the regeneration,

we chose a gap size of 0.2 ha, slightly larger than most 

natural gaps (Seymour et al. 2002). Further, we designated

about 10 percent of the initial growing stock as permanent

reserve trees, making this a “group shelterwood with

reserves.” We chose to carry out the conversion cuttings in

five entries spaced 10 years apart, and then allow the stand

to develop without regeneration cutting for another 50 years.

This equals a 1-percent annual disturbance rate over the

entire 100-year conversion period, but is effectively “frontloaded” during the first 50 years at 2 percent per year.

Unlike a classical group selection system with a constant

cutting cycle, this system explicitly does not attempt to

achieve any sort of balanced within-stand age structure,

just a diverse, irregular one that nevertheless represents

quite a departure from the initial single-cohort structure.

The most accurate description of this system using contemporary North American silvicultural terminology would

be an “irregular group shelterwood with reserves.” Group

comes from the spatial pattern of the cuttings and is needed

to distinguish it from a uniform application. Irregular comes

from the extended regeneration period relative to a more

conventional shelterwood, and describes the uneven height

structure of the resulting regeneration. With reserves comes

from the retention of trees from the original cohort beyond

the regeneration period, for reasons unrelated to the regeneration process itself. European foresters have long applied

such a system, known in Germany as the Femelschlag, in

which the groups under regeneration are expanded at each

entry until they coalesce (Spurr 1956). In his classic

description of European silvicultural systems, Troup (1928)

describes several regional variants of the Femelschlag

widely practiced at that time for converting even-aged stands

to more irregular structures. We have also adopted this

approach in our FERP experiments, and have thus chosen

to describe our system as the Acadian Femelschlag. 

Some Application Details: Locating Skid Trails, 

Initial Gaps, and Reserve Trees

We elected to harvest within the matrix between groups

during the first entry, mainly to presalvage balsam fir, paper

birch, and aspen that were reaching their natural life span.

In the matrix, we were very careful not to remove any large

dominant trees that would make permanent canopy gaps

and thus create unwanted nuclei of regeneration. Skid trails

were designated to connect the gaps, and occasional spur

trails were needed to treat the intervening matrix. In future

entries when gaps are expanded, trails will be relocated

through the matrix where necessary to avoid damaging

established reproduction.

Initial gaps were located in two different stand conditions. In patches of well-established advance regeneration

resulting from partial canopy breakup in the two decades

prior to initiating the experiment, the overstory was removed

completely except for the requisite reserve trees. Areas of

these existing gaps were estimated in the field and sketched

on a stand map. Additional gaps were located as needed

throughout the more intact matrix until the requisite area

(20 percent of the total stand) was achieved. In this latter

case, the cut within the gap attempted to leave a shelterwood overstory basal area of 14-18 m2/ha (60 to 80 ft2/acre)

to provide shade and seed for new recruitment. These overwoods will be removed in the second entry (except permanent reserve trees) as the gaps are expanded.

Reserve trees were designated at the same time the stand

was marked for cutting. Any tree with obvious wildlife

usage (e.g., large cavities) was designated; others were

selected from the larger d.b.h. classes of long-lived, and

sometimes uncommon, species. Since our goal was to permanently retain 10 percent of the stand, and the target

residual basal area, including gaps, was about 23 m2/ha

(100 ft2/acre), we used a 10 basal area factor (English)
46

wedge prism to distribute reserve trees such that no place

in the stand was lacking at least one “in” tree.

Quantifying What Is “Natural” as a Silvicultural

Benchmark

Silviculturists in the Northeast seeking to emulate natural disturbance regimes have historically relied on general

ecological principles and intuition. To overcome this obstacle, we created a simple metric based on a comprehensive

review of disturbance literature for the region that allows

foresters to assess how closely their silvicultural systems

approach natural patterns (fig. 1). The axes of the diagram—

intervals between disturbance and contiguous areas disturbed—both have direct silvicultural analogues (Seymour

and Hunter 1999). For systems that do not regenerate the

entire stand in one entry (e.g., group selection), the frequency should be thought of as the time required to regenerate the entire stand, assuming patches do not overlap. This

is given by the formula: frequency (or effective rotation) =

(cutting cycle, in years)/(proportion of stand regenerated at

each entry). The fitted line that bounds the upper limit of

the disturbance data becomes the space-time benchmark

point for any system.

Consider a group-selection system that regenerates 20

percent of the stand at each entry, in patches averaging 0.2

ha, on a 10-year cycle. The return interval (effective rotation) is thus 10/20% = 50 years. Next, compute the natural

return interval of a 0.2-ha patch: Interval = [0.2 x 108.2]

0.2764 = 101 years (from fig. 1). The ratio of the planned

return interval to its natural analogue is termed the natural

disturbance comparability index, in this case 50/100 = 0.5,

meaning that such a system would effectively regenerate

this stand in gaps of this size about twice as rapidly as natural disturbances would. Note that lengthening the cutting

cycle to 20 years, or reducing the patch size to 0.014 ha,

would place the system exactly on the line. The Acadian

Femelschlag described above also falls exactly on the line

because the entire “rotation” (the time between the beginning of gap creation in two successive applications of the

system to the same area) is effectively 100 years (50 years

of group regeneration cutting followed by 50 years of stem

exclusion stand development during which only intermediate treatments are applied).

It is also instructive to compare the planned age distribution of the irregular group shelterwood with that of undisturbed old-growth stands in the region. The age structure of

the shelterwood will be, by design, distinctly bimodal: five

closely spaced cohorts that span a range of about 40 to 50

years resulting from the expanding gap cuttings, plus a population of much older reserve trees chosen from the initial

stand. For example, if the stand were 90 years old at the

beginning (as in the case of one of the FERP experimental blocks), by the time the regeneration process is complete, these reserves will be 140+ years old, and nearly 200

after one complete cycle when the stand is again ready for

regeneration cuttings. 

Figure 2 shows the age structure of three old-growth red

spruce stands in the Big Reed Reserve in northern Maine

as reconstructed by Fraver (2004). Note that all are somewhat bimodal, two distinctly so, indicating that recruitment

in such stands is episodic and irregular. Note that irregular

group shelterwood systems with reserves—with extended

periods of stand regeneration in patches, followed by periods

of stem exclusion—arguably emulate this structure more

faithfully than the classic balanced single-tree or group

selection stand with continuous, temporally constant recruitment. In the group shelterwood, the managed cohorts would

be analogous to those under age 100 in the natural forest,

and the reserve trees would be analogous to the old-growth

trees over the managed rotation (ca. 100 years). In practice,

a managed stand would have more growing space allocated

to cohorts under age 100 and less to the old-growth legacy,

assuming legacy trees would never be harvested.

CONCLUSIONS

Irregular group shelterwoods with permanently retained

reserve trees offer great promise as a viable method to

restore age diversity and “naturalness” to Acadian forests

that have become simplified from over a century of heavy

cutting. Like any silvicultural system, however, they are not

a panacea for all conditions, even where landowners are

committed to ecological restoration. In pure, single-cohort

stands dominated by early successional species, restoration

of later-successional species which may invade the understory is the main ecological objective, and uniform shelterwoods (with reserves) may offer the only way to capture

the value in the present stand before it reaches maturity. In

this case, restoration of age structure can then begin during

the next rotation, where the presence of more long-lived

species offers more options. Conversely, in stands that have

been managed to retain multi-aged, late-successional qualities, some form of selection cutting with more regular

entries and smaller gaps may be more appropriate.

ACKNOWLEDGMENTS

Funding for this Forest Ecosystem Research Program

has come primarily from the Maine Forest and Agriculture

Experiment Station. This paper benefited substantially from

reviews by Laura Kenefic, David Ray, and Robert Wagner.
47

Figure 2—Age-structures of three old-growth red spruce stands in the Big Reed Reserve, T. 8 R. 10, Maine (Fraver 2004), showing the very irregular patterns of canopy recruitment over three centuries. Group shelterwood silvicultural systems can mimic this

pattern, assuming the 1-100 cohorts represent the managed (harvested) stand, and those over 100 are reserve trees that provide the

biological legacy. In practice, a managed stand would have more trees in the “managed” component and fewer in the old-growth

legacy.
48

REFERENCES

Cary, A. 1894. On the growth of spruce. Second annual 

report, Maine Forest Commissioner, Augusta, ME: 20-36.

Curtis, R.O. 1998. “Selective cutting” in Douglas-fir:

revisited. Journal of Forestry. 96(7): 40-46.

Franklin, J.F.; Berg, D.R.; Thornburgh, D.A.; Tappeiner, 

J.C. 1997. Alternative silvicultural approaches to timber

harvesting: variable retention harvest systems. In: Kohm,

K.A.; Franklin, J.F., eds. Creating a forestry for the 21st

century. Washington, DC: Island Press: 111-139.

Fraver, S. 2004. Spatial and temporal patterns of natural 

disturbance in old-growth forests of northern Maine,

USA. University of Maine. 185 p. Ph.D. dissertation.

Hannah, P.R. 1988. The shelterwood method in northeastern forest types: a literature review. Northern Journal 

of Applied Forestry. 5: 70-77.

Hosmer, R.S. 1902. A study of the Maine spruce. In: 4th 

Rep. Maine Forest Commissioner, Augusta, ME.

Lorimer, C.G.; White, A.S. 2003. Scale and frequency of 

natural disturbances in the northeastern United States:

implications for early successional habitat and regional

age distributions. Forest Ecology and Management.

185: 41-64. 

Nyland, R.D. 1996. Silviculture: concepts and applications. 

New York: McGraw-Hill. 633 p.

Nyland, R.D. 2003. Even-to uneven-aged: the challenges 

of conversion. Forest Ecology and Management. 

172: 291-300.

O’Hara, K.L. 1996. Dynamics and stocking-level relationships of multi-aged ponderosa pine stands. Forest

Science. 42(4): Monograph 33.

Oliver, C.D.; Larson, B.C. 1996. Forest stand dynamics. 

New York: John Wiley and Sons, Inc. 520 p.

Sendak, P.E.; Brissette, J.C.; Frank, R.M. 2003. Silviculture 

affects composition, growth, and yield in mixed northern conifers: 40-year results from the Penobscot

Experimental Forest. Canadian Journal of Forest

Research. 33: 2116-2128.

Seymour, R.S. 1992. The red spruce-balsam fir forest of 

Maine: Evolution of silvicultural practice in response to

stand development patterns and disturbances. In: Kelty,

M.J.; Larson, B.C.; Oliver, C.D., eds. The ecology and

silviculture of mixed-species forests. A festschrift for

David M. Smith. Norwell, MA: Kluwer Academic

Publishers: 217-244. Chapter 12.

Seymour, R.S. 1995. The Northeastern Region. In: Barrett, 

J.W., ed. Regional silviculture of the United States. 3rd

ed. New York: Wiley and Sons: 31-79.

Seymour, R.S. [In press]. Silviculture: lessons from our 

past, thoughts about the future. In: Palik, B.; Levy, L.,

eds. Great Lakes Silviculture Summit, proceedings.

Gen. Tech. Rep. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Research

Station. 

Seymour, R.S.; Hunter, M.L., Jr. 1999. Principles of ecological forestry. In: Hunter, M.L., Jr., ed. Maintaining

biodiversity in forest ecosystems. New York: Cambridge

University Press: 22-61. Chapter 2. 

Seymour, R.S.; Kenefic, L.S. 1998. Balance and sustainability in multi-aged stands: a northern conifer case

study. Journal of Forestry. 96(7): 12-17.

Seymour, R.S.; White, A.S.; deMaynadier, P.G. 2002. 

Natural disturbance regimes in northeastern North

America – evaluating silvicultural systems using natural

scales and frequencies. Forest Ecology and Management.

155: 357-367.

Smith, D.M. 1986. The practice of silviculture, 8th ed. 

New York: Wiley and Sons. 527 p.

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1997. The practice of silviculture: applied forest ecology.

9th ed. New York: Wiley and Sons. 537 p.

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Oxford Universiyt Press. 216 p.
1 Associate Professor , Oregon State University, Department of Forest Science, 321 Richardson Hall, Corvallis, OR 97331-5752. 

Email: klaus.puettmann@oregonstate.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Do Innovative Experiments Lead 

to Innovative Silvicultural Systems?

Klaus J. Puettmann1

INTRODUCTION

The controversy over forest management in the Pacific

Northwest (PNW) of the United States in the late 1980 and

early 1990s questioned the ability of traditional silvicultural

systems to satisfy the range of landowner objectives, especially on public land. This uncertainty resulted in an effort

to establish several large-scale management experiments or

LSMEs (see Monserud 2002). The experimental approach

of LSMEs is quite innovative: these studies include multiple

objectives covering a variety of scales and disciplines and

thus facilitate integration of a suite of ecosystem responses.

In addition, treatments are applied to large experimental units

and results can be directly transferred to standard management operations. Although all LSMEs have commonalities,

the range of study approaches reflects the variety of forest

conditions and management objectives across the region

and ownerships. Table 1 provides an overview of initial

objectives and treatments for several innovative studies.

Experiments that deal with final harvest situations (the first

four studies) linked their objectives closer to silvicultural

systems than studies that dealt with intermediate stand

treatments (the last three studies). This is likely due to the

dominance of final harvests in defining silvicultural systems.

Some experiments were set up to directly test silvicultural

ABSTRACT

Innovative experiments provide a unique opportunity to facilitate development of new, innovative silvicultural systems.

Experiments with clear objectives and expectations can be set up to provide information about a set of silvicultural treatments, thus testing silvicultural systems directly. Innovative experiments are especially useful for investigation of large-scale

treatments and responses and provide opportunities for investigation of small-scale responses under a wide range of treatments. To fully utilize these experiments requires coordination of studies and “innovative” integration of results.

KEYWORDS: Silvicultural systems, large scale assessment, small scale ecosystem responses, integration.

49

systems, e.g., the Montane Alternative Silvicultural Systems

study or Capitol Forest study. A second set of studies have

a more limited scope and document whether a specific silvicultural practice, such as thinning or variable retention,

hasten development of late successional attributes, e.g., the

Young Stand Thinning and Diversity study or Demonstration

of Ecosystem Management Options study. 

Silvicultural systems outline future conditions, values,

and practices necessary to reach desired objectives, and all

of these aspects are important when evaluating innovative

experiments. Silvicultural systems are typically defined by

the regeneration system, competition control, fertilization

regimes, intermediate manipulations of stand density and

composition, and, primarily, by the method of harvest, i.e.,

they deal with all stages of stand development and integrate

information from various disciplines. Consequently, most

ecological and silvicultural research projects can provide

useful information. However, studies that are defined by 

a coordinated set of treatments or manipulations are more

relevant to assessment and development of silvicultural

systems. Table 1 lists the proposed treatments as stated in

initial study plans of innovative experiments. A clear understanding of desired future conditions seems to be indicative

of more detailed description of future treatments. Studies
50

with investigation of silvicultural systems as the main objective generally define the set of overstory treatments in accordance with the systems that are investigated. Information in

these study plans includes tentative schedules for follow-up

cuttings, such as removal cuts in shelterwoods or subsequent

entries in group selections. With notable exceptions, the study

plans provided less information about snag and downed

wood management and treatment of soil, regeneration, and

understory vegetation. Although future treatments may have

to be flexible to accommodate unexpected trends and

developments, a clear hierarchy of objectives (see Ganio

and Puettmann 2005) will facilitate definition of future

treatments. For example, a clear definition of desired stand

structure determines the role of understory hardwoods and

multiple layers of a conifer canopy and is necessary for

defining future treatments of understory vegetation and

conifer regeneration. If the development of multiple conifer

overstory canopy layers has priority, vegetation management

Table 1—Objectives and treatments of selected large-scale management experiments, as listed in their initial study

plans 

Additional 

Study Objective Treatment type treatments Source

Capitol Forest Compare different silviculture Clearcut, retention, patch (If needed) over Curtis et al. 2004

regimes cut, group selection, and understory

thinninga manipulations

Alternatives to Determine how even-and uneven-age Clearcutting, patch McClellan et al. 

clearcutting silvicultural systems affect stand retention, single tree 2000

features and process selection, group 

selection. (uniform and 

patchy)b

Montane Test alternative silviculture systems Patch cut, green tree Beese and 

Alternative retention, shelterwood Bryant 1999

Silvicultural cut, clearcut

Systems

Date Creek Examine ecosystem processes in 2 levels of partial cutting, Coates et al.

uncut, partially cut, and clearcut clearcut 1997

stands

Demonstration Study ecological and social effect of 4 retention levels, Aubry et al. 

of Ecosystem variable retention harvest dispersed and 2004

Management aggregated

Options

Forest Test whether late-seral forest Variable density thinning 2nd thinning Carey et al. 1999

Ecosystem attributes can be developed (repeated), entry,

Study (hastened) through silviculture underplanting underplanting

Young Stand Test whether different thinning, 2 thinning intensities, http://www.fsl.

Thinning and underplanting, and snag creation gap creation, orst.edu/

Diversity treatments can accelerate the ccem/youngstd/

Study development of late-successional home.htm

habitat

Density Determine if density management 3 thinning intensities Overstory Thompson and 

Management treatments result in differences in (homogenous and treatments, Larsen 2003

Study stand structure and habitat diversity variable), gap creation, precommerical

leave island thinning

a May imply multiple overstory manipulations in accordance with silvicultural system. 

b Usually includes an uncut control treatment.
51

to provide good growing conditions for conifer regeneration

is desirable or necessary. On the other hand, if the desired

future stand structure includes diverse understory vegetation

with a shrub and hardwood layer, these components should

not be removed, even though they may impact growth of

regenerating conifers. 

The study plans also highlight the importance in distinguishing between the two approaches. The first compares

effects of implementing different silvicultural systems,

whereas the second provides opportunities to improve our

understanding of processes important for developing and

implementing silvicultural systems. These approaches are

not mutually exclusive, but the distinction is reflected in the

definition of study objectives and treatments and has to be

kept in mind throughout the discussion below. 

LARGE-SCALE AND LONG-TERM

ASSESSMENTS OF TREATMENTS

A defining factor, treatment unit size has a great impact

on scientific contributions of innovative experiments. Treatment unit size is experimentally driven by the context of

processes and structures studied in the experiment, i.e., by

the phenomena of interest with the largest extent (see Wiens

1989). For many studies in the PNW, the size was defined

by songbirds. To ensure multiple home ranges of songbirds

within treatment units (Hagar 2001), treatments in the PNW

were commonly applied to 40- to 50-acre units, similar to

typical stand sizes in the region. The large experimental

units ensure that results from application and assessment of

treatments are directly applicable to stand-level management

practices. Consequently, innovative experiments provide

unique opportunities to develop information about issues

for which information from smaller experiments cannot be

scaled up because the assumption of scale-independent uniformity is not met. Another example of questions that require

stand-level studies focuses on operational aspects of silvicultural systems. Innovative experiments have provided information about cost of layout and hauling for newly developed

silvicultural treatments, such as creation of small gaps as

part of a thinning operation (Kellogg et al. 1998). Other

harvesting aspects, such as the amount of damage to residual trees or distribution and impacts of slash, also require

stand-level assessments. A third set of issues that benefit

from innovative experiments includes public perceptions 

of silvicultural systems. 

Due to their size, treatments in innovative experiments

are commonly implemented as part of “normal” management

operations. This provides opportunities for technology transfer

and will facilitate future adaptations of innovative silvicultural systems. On the other hand, operational implementations can limit the choice of treatments because of logistical

considerations or reluctance of managers to implement

treatments that go beyond commonly accepted standards. 

The inherent long-term nature of innovative experiments

will provide information on issues that do not lend themselves to temporal scaling. Although models exist that predict tree development in typical stand conditions quite well,

the prediction of other responses may be more complicated

and require longer time scales for investigations. For example, predicting regeneration of tree or other plant species or

size and trends of wildlife populations includes stochastic

elements that are not easily quantified in short, small-scale

experiments. The size and long-term nature of innovative

experiments may allow investigation of stochastic patterns

and the variability of responses. Similarly, natural disturbances are usually stochastic, and their interaction with

natural ecosystem development and management practices

is sometimes ignored in management planning. Innovative

experiments may provide an opportunity to document their

frequency, patterns and impacts under different treatment

regimes. 

SMALL-SCALE ASSESSMENT

OF ECOSYSTEM PROCESSES

A second advantage of innovative experiments is that

they provide opportunities for small-scale and short-term

studies. Many processes, such as seedling responses to

overstory cover, act on scales smaller than the stand level.

In homogenous treatment units, these aspects can be studied at larger scales to provide a better understanding of the

variation of responses. A large number of subsamples can

provide an estimate of variation around the mean, thus allowing researchers to quantify the distribution of responses. A

second option to investigate small scale processes is to

ignore scale discrepancies and study them by using a smaller

grain (see Wiens 1989). For example, to study seedling

responses to overstory cover, large, evenly-spaced thinned

treatment units may be supplemented with small underplanted plots. In this context, large-scale treatments that are

highly variable provide better opportunities to gain more

information about small-scale ecosystem processes. One

common example is when stand-level treatments are a combination of subtreatments, such as gaps placed randomly in

an evenly spaced matrix (e.g., in the Young Stand Thinning

and Diversity study). Under this setup, comparisons of (small

scale) conditions in gaps and matrix may provide useful

information. Alternatively, innovative studies provide opportunities to investigate aspects relating to the whole set of
treatments that are part of silvicultural systems, such as the

performance of different species, the impact of fertilization,

or weed control under a range of overstory conditions

(created by the stand-level treatments). 

Further opportunities to take advantage of the range of

conditions created by large-scale treatments in innovative

experiments include more detailed analyses of within-treatment variation. Highly variable treatments, such as variable

density thinning, may result in a wide gradient of conditions. In many cases, a clear distinction (e.g., where a gap

stops and a matrix begins) is not always possible or even

desirable. Instead, conditions change gradually, thus resulting in large experimental gradients over a small spatial

scale. Common gradients include the transition from closed

canopy stands to clearcuts or gradients from gaps or leave

islands into thinned stands. Using a common independent

variable, such as overstory cover, allows investigations of

gradients under the range of conditions found in innovative

experiments. Examples include gradients starting in matrices with different densities or gradients ending in gaps or

leave islands of different sizes. This provides opportunities

to gain detailed information about the scale of variability

and underlying mechanisms. It also helps in understanding

the average treatment response. In addition, this information provides foresters with an opportunity to quantify

tradeoffs when choosing the range and spatial layout of

treatments in new silvicultural systems. Better ecological

understanding may also be helpful when implementing

innovative silvicultural system in stands that are outside 

the scope of the studies. 

INTEGRATION OF STUDIES

A third unique feature of innovative experiments is the

multitude of objectives and investigators. Most experiments

provide information on a range of ecosystem responses,

including overstory trees, understory vegetation, mycorrhizal associations, and animal habitat and populations.

Multidisciplinary assessments of silvicultural systems are

of special interest on ownerships with a complex set of

management objectives or constraints. Integrating results

from various disciplines into complex descriptions of ecosystem responses is very difficult and has been slow to

develop. This is at least partially due to the lack of a coordinated study effort. Information about different ecosystem

responses is commonly derived from an array of experiments

with different initial conditions, treatments, assumptions,

etc. Researchers involved in innovative experiments have

the opportunity to plan for integration up front. Not only

do innovative experiments have the benefits of common

experimental designs and treatments, they also provide the

opportunity to implement an experimental layout that is

specifically designed to facilitate integration of information from various disciplines (see Ganio and Puettmann

2005). To accomplish this requires standardizing procedures

and coordinating timing and location of data collection 

and analysis.

Using information gained from innovative experiments

to develop new, creative silvicultural systems requires additional steps. I suggest that innovative analytical methods be

developed and used to fully take advantage of innovative

experiments. The use of analytical or predictive modeling

approaches that integrate information from short-term and

small-scale investigations may be especially beneficial.

These models have to accommodate spatial and temporal

variability so we can understand silvicultural systems that

include complex stand structures. Models with small spatial resolution are better able to account for variation inherent to site or vegetation conditions. As highlighted above,

innovative experiments can provide information about

stochasticity and variability of responses, and this should be

included into the models. For example, treatment responses

could be determined stochastically, i.e., data from innovative experiments would provide the probability of tree

regeneration. A random number generator would then be

used to decide the fate of each gap. Alternatively, or additionally, the simulation models could predict the distributions rather than average response. These models may have

limitations in predictive accuracy for any single location

within a stand. However, they can use a variety of information sources, take advantage of the unique features of innovative experiments, and thus can be a very powerful tool in

developing hypotheses and predicting ecosystem response

to new, creative silvicultural systems (for examples, see

Coates et al. 2003). 

REFERENCES

Aubry, K.B.; Halpern, C.B.; Maguire, D.A. 2004. Ecological 

effects of variable-retention harvests in the northwestern

United States: the DEMO Study. Forest Snow and

Landscape Research. 78: 119-138.

Carey, A.B.; Thysell, D.R.; Brodie, A.W. 1999. The forest 

ecosystem study: background, rationale, implementation, baseline conditions, and silvicultural assessment.

Gen. Tech. Rep. PNW-GTR-457. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station. 129 p.

52
53

Coates, K.D.; Banner, A.; Steventon, J.D.; LePage, P.; 

Bartemucci, P. 1997. The Date Creek silvicultural systems in the interior cedar-hemlock forests of Northwestern

British Columbia: Overview and treatment summaries.

Land Management Handbook 38. British Columbia

Ministry of Forests Research Program. 129 p.

Coates, K.D.; Canham, C.D.; Beaudet, M.; Sachs, D.L.; 

Messier, C. 2003. Use of a spatially explicit individualtree model (SORTIE/BC) to explore the implications of

patchiness in structurally complex forests. Forest

Ecology and Management. 186: 297-310.

Curtis, R.; Marshall, D.D.; DeBell, D.S. 2004. Silvicultural 

options for young-growth Douglas-fir forests: the

Capitol Forest study—establishment and first results.

Gen. Tech. Rep. PNW-GTR-598. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station. 110 p.

Ganio, L.M.; Puettmann, K.J. 2005. Design challenges in 

large-scale management experiments. In: Peterson,

C.E.; Maugire, D., eds. Balancing ecosystem values:

innovative experiments for sustainable forestry, proceedings. Gen. Tech. Rep. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 

Hagar, J. 2001. Songbird community response to thinning 

of young Douglas-fir stands in the Oregon Cascades –

third year post-treatment results for the Willamette N.F.,

young stand thinning and diversity study. Oregon State

University, Department of Forest Science, Corvallis,

OR. 7 p. www.fsl.orst.edu/ccem/pdf/POSTYR3.pdf 

Kellogg, L.D.; Milota, G.V.; Stringham, B. 1998. Logging 

planning and layout costs for thinning: experience from

the Willamette Young Stand project. Oregon State

University, College of Forestry, Forest Research

Laboratory. FRL Research Contribution 20. 

McClellan, M.H.; Hennon, P.E.; Deal, R.L.; De Santo, 

T.L.; Wipfli, M.S. 2000. Alternatives to clearcutting in

the old-growth forests of southeast Alaska: Study plan

and establishment report. Gen. Tech. Rep. PNW-GTR494. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range

Experiment Station. 40 p.

Monserud, R.A. 2002. Large-scale management experiments in the moist maritime forests of the Pacific

Northwest. Landscape and Urban Planning. 59: 159-180.

Thompson, C.; Larsen, L. 2003. Density management studies status report. (Draft) Oregon/Washington Bureau of

Land Management. 53 p. On file with: K. Puettmann,

Oregon State University, Department of Forest Science,

321 Richardson Hall, Corvallis OR, 97331, USA. 

Wiens, J.A. 1989. Spatial scaling in ecology. Functional 

Ecology. 3: 385-397.
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1 Forest Ecologist, Weyerhaeuser, BC Coastal Timberlands, 65 Front Street, Nanaimo, BC, V9R 5H9, Canada. Email for corresponding author:

Bill.Beese@weyerhaeuser.com

2 Glen Dunsworth Ecological Consulting, 7857 Shangri-la Road, Lantzville, BC V0R 2H0, Canada

3 Manager, Growth and Yield, Weyerhaeuser, BC Coastal Timberlands, 65 Front Street, Nanaimo, BC, V9R 5H9, Canada

Balancing Ecosystem Values Proceedings, Regional Experiments

Variable-Retention Adaptive Management Experiments: Testing 

New Approaches for Managing British Columbia’s Coastal Forests

William J. Beese,1 B. Glen Dunsworth,2 and Nick J. Smith3

INTRODUCTION

In recent years, changing public values and scientific

knowledge have led forest practices toward achieving

broader objectives on public forest lands in British Columbia

(BC). Global concerns about biological diversity have

raised demand in the marketplace for wood from forests

under sustainable forest management certification. In 1998,

MacMillan Bloedel (now Weyerhaeuser, BC Coastal Group)

announced “The Forest Project”—an innovative forest

management strategy designed to achieve a balance of

ABSTRACT

In response to changing public values and scientific knowledge, the variable-retention (VR) approach to forest harvesting has become widespread on forest lands in coastal British Columbia (BC). Variable retention is both a tool for achieving

stand-level objectives, such as retention of trees to enhance structural diversity, and an important strategy for achieving forestlevel goals, such as conservation of biodiversity. The VR approach can be applied using the new retention silvicultural

system, officially adopted in BC, or by adapting traditional systems with long-term reserves. 

Weyerhaeuser’s BC Coastal Timberlands is implementing an innovative forest management strategy that includes the

use of landscape zoning, variable retention and adaptive management to balance ecological, social and economic objectives.

The program includes monitoring of both operational cutblocks and operational-scale experiments. A set of long-term, variable-retention adaptive management (VRAM) experiments were designed by a team of scientists and foresters to address

many of the questions regarding the layout and objectives for VR cutblocks. Fifteen VRAM blocks are being installed by

our BC coastal operations over a 7-year period. There are three replicates of five comparisons: group retention level, group

size, dispersed retention level, riparian retention level, and short- or long-cycle group selection. Each VRAM block consists

of five 20 ha treatments: three VR options, clearcut, and uncut. To date, four VRAM sites have been logged and four are

scheduled for completion in 2004. Monitoring includes a focused set of attributes and organisms. An adaptive management

framework was designed so that results will feed back to management. 

KEYWORDS: Adaptive management, biodiversity, British Columbia, variable retention.

55

ecological, social and economic goals for managing over

1.1 million hectares (ha) of mainly public forest land in

coastal BC. The strategy includes landscape zoning, increasing old-growth conservation, adopting variable retention

harvesting, implementing a monitoring and adaptive management program, and achieving independent forest certification. This program, now known as Weyerhaeuser’s BC

“Coast Forest Strategy,” is described by the authors in previous articles (Beese 1998, Beese et al. 2001, Dunsworth

and Beese 2000) and on a website (www.forestry.ubc.ca/

conservation/forest_strategy). 
Use of the variable retention (VR) approach to harvesting is a recent development in BC; the term was first introduced by the Clayoquot Scientific Panel (1995) and subsequently described in a broader context by Franklin et al.

(1997). Prior to this, there was very little experience in

using partial cutting silvicultural systems in the old-growth

forests of the BC coast (Arnott and Beese 1997). In 1999,

the BC government officially recognized the “retention silvicultural system” in its forestry regulations. Weyerhaeuser

phased-in VR throughout BC coastal operations over a 5-

year period, completing over 90 percent of our harvesting

using VR in 2003. 

One of the goals of the Coast Forest Strategy is to sustain biodiversity, or biological richness and its associated

values, within Weyerhaeuser’s BC coastal tenure. We use

three indicators of success to focus our goals and monitoring (Kremsater et al. 2003):

1. Ecologically distinct ecosystem types are represented 

in the nonharvestable landbase to maintain lesser known

species and ecological functions.

2. The amount, distribution, and heterogeneity of stand and

forest structures important to sustain biological richness

are maintained over time.

3. Productive populations of forest-dwelling species are

well distributed.

Because the effectiveness of variable retention and broad

landscape zoning in maintaining biodiversity is largely

untested, adaptive management is a key component of the

Coast Forest Strategy. Adaptive management is “a dynamic

approach to forest management in which the effects of

treatments and decisions are continually monitored and

used, along with research results, to modify management on

a continuing basis to ensure that objectives are being met”

(Helms 1998). We need to examine the impacts of our

practices on both biodiversity and our ability to manage

forests for commercial production; therefore, linking monitoring back to management action is a fundamental component. The program will evaluate biological indicators by

monitoring both operational treatments (i.e., normal business

practices) and designed experimental treatments. The focus

of this paper is to describe the adaptive management experiments that are being implemented as part of the Coast

Forest Strategy.

OBJECTIVES

Variable-retention adaptive management (VRAM)

experiments were designed by a team of scientists and

foresters to address many of the questions regarding the

layout and objectives for VR cutblocks. The objectives 

of these experiments are to

1. Establish a series of designed comparisons of variable

retention options to support an adaptive management

approach;

2. Compare a range of retention levels and spatial patterns

of retention in several forest types;

3. Monitor the short-term and long-term impacts of 

variable retention options on forest growth, structural

attributes and selected forest-dwelling plant and animal

species. 

VRAM sites focus on the stand-level questions associated with biodiversity indicators 2 and 3 above (forest

structure and species) as well as the silvicultural implications of VR options. Key questions include: What is the

effect of the amount (percentage of retention level) and

pattern of retention (dispersed trees, small groups, large

groups)? What is the effect of size of opening and timing

of adjacent openings? What is the effect of group location

on small stream-riparian impacts?

METHODS

Experimental Design

The experimental design for the VRAM areas consists

of three replicates for each of five comparisons:

1. Group retention levels: 10-percent, 20-percent, and 

30-percent group retention; groups range in size from

0.2 to 0.5 ha.

2. Dispersed retention levels: 5-percent, 10-percent, and

30-percent dispersed retention; single trees to small

groups up to 0.1 ha.

3. Group size: large groups (0.8 to 1.2 ha), small groups

(0.2 – 0.5 ha), and dispersed trees (single trees to very

small groups up to 0.1 ha); the retention level is 15 percent for all treatments.

4. Group removal – short/long cycle: group removal –

short cutting cycle (5 to 7 years), group removal – long

cutting cycle (20 to 30 years); groups in both treatments

range in size from 0.1 to 1.0 ha. 

56
5. Riparian retention: 0 percent, 15 percent and 50 percent

of the length of small streams within treatments are covered by group retention (i.e., 0.25 ha or larger groups); a

retention level of 15 percent is maintained within all

stream catchments.

Each VRAM block consists of five 20 ha treatments:

three VR options, clearcut and uncut (fig. 1). Each VRAM

site requires an area of 80 to 100 ha that is as uniform as

possible in timber type, plant associations, and topographic

features. Several cutblocks in close proximity can be used

in place of a single contiguous area. Potential areas are

evaluated for suitability by the science team. Forestry planners then complete a preliminary layout of treatment blocks.

Treatments are randomly allocated to blocks before field

layout commences. Regular communication occurs between

the scientists and planners during layout to ensure that the

objectives are met and the study design is not compromised.

The 15 VRAM blocks are being installed by our six BC

coastal timberlands units over a 7-year period as part of their

annual harvest operations. At least of one the three sites for

each comparison will be in an old-growth forest type. 

57

Variable-retention comparison blocks

Group Retention: Variable percentage

of area retained; group sizes range

from 0.2 to 0.5 ha

Riparian Retention: All catchments retain 15%

Groups are retained along streams to represent

0%, 15%, 50%, and 100% of the stream length

Group Removal: All treatment retain 15%

Short cutting cycle — every 5 to 7 years

Long cutting cycle — every 20 to 30 years

Dispersed Retention: Variable basal

area retained; single trees or small

group up to 0.1 ha

Group Size: All treatment retain 15% of area

Large groups — 0.8 - 1.2 ha

Medium groups — 0.2 - 0.5 ha

Small group up to 0.1 ha

Figure 1—Diagram of variable-retention adaptive management experiments.
Each of the VR options must meet the requirements of

the “retention silvicultural system,” which is the most common system used for implementing the variable retention

approach. The retention system maintains enough tree

canopy to have forest or residual tree influences on the

majority of a cut area, and leaves long-term live and dead

tree reserves of varying sizes and canopy layers, distributed

throughout harvested areas (Forest Practices Code of BC

Act 1999). Mitchell and Beese (2002) describe the retention

system and its rationale as a silvicultural system. To simplify

the operational implementation of the retention system, our

company guidelines state that retained groups of trees should

be greater than 0.25 ha in size and no more than 4 tree

lengths apart; individual trees or smaller groups should be

no more than 2 tree lengths apart. Consequently, no place

within a cutblock is more than 2 tree lengths from some

standing trees. These guidelines are flexible, but they ensure

that retention is well distributed within a cutblock and that

the forest influence criterion is achieved (Beese et al. 2003).

The minimum group size ensures that understory habitat

attributes are retained, such as undisturbed shrubs and

mosses, and allows retention of dead trees with an unharvested buffer around them for worker safety.

The group removal comparison includes some additional

specifications. Each group removal treatment retains 15

percent of the area in long-term retention. Harvesting of

groups takes place over three passes at the prescribed intervals. In conventional terms, the short- and long-cycle treatments could be considered group shelterwood and group

selection systems. Each treatment must have at least 3

examples of the following size classes per pass: 1.0, 0.5,

0.25 and 0.1 ha (a total of 9 each). Different sized groups

must be intermixed throughout the block, not concentrated

in one portion of the block. Other considerations for this

treatment include planning for permanent access skid roads,

felling snags in adjacent groups that could pose a danger 

to workers, orientation of groups to maximize light (northsouth) and layout of groups to facilitate falling and yarding.

Development and implementation of VRAM experiments

are overseen by two working groups. The VR working

group, which is responsible for developing guidelines and

recommending policies for VR implementation, consists of

members from each timberlands unit and research specialists.

Members chose which comparisons their unit would undertake in order to get a good distribution of blocks across site

conditions on the BC coast. Timberlands track production

and costs by treatment so that economic comparisons can

be made. The adaptive management working group, which

guides the implementation of the program, reviewed the

experimental design and developed a framework for monitoring. 

Structure Monitoring

Permanent transects are established in all VRAM treatment units to measure the following habitat elements:

• live trees (species, diameter, and height),

• snags (species, diameter, height, and decay class),

• coarse woody debris (species, diameter, and decay class),

• cover layers (canopy, small tree, shrub, herb, moss, litter,

and mineral soil), and

• dominant shrub and herb species.

The sampling for dispersed retention cutblocks and the

harvested portions of mixed retention blocks used 25 m x

25 m plots to measure live trees, nested within 50 m x 50 m

plots in which snags and large trees were recorded. Coarse

woody debris was measured along intercept transects of 50 m

(for all sizes) or 100 m (for pieces >30 cm) on two perpendicular sides of the plot. Cover variables, dominant plants,

and site series (plant associations) were recorded in five

0.01-ha circular sub-plots across the larger plot. Two plots

were established per cutblock. 

In areas with group and mixed retention, transects were

used across the boundaries of retained patches, extending

up to 50 m into the patch and 50 m into the opening. All

trees within 2.5 m of the transect were recorded, as were

all snags and large trees within 5 m. Coarse woody debris

was recorded along both the main transect and 10-m-long

transects running perpendicular to the main transect every

10 m. Trees, snags, and coarse woody debris were recorded

separately in 10-m transect segments (i.e., 0–10 m from the

edge, then 10–20 m, 20–30 m, etc.). Every 10 m along the

main transect, 0.01-ha circular plots were used to assess

cover layers, dominant plants, and site series. Two transects

were established in each of three patches per cutblock.

Species Monitoring

The focus of species monitoring has been to evaluate 

a range of potential indicator or focal organisms for future

monitoring. Obviously we cannot afford to monitor all

species. There are about 200 vertebrates alone that potentially occur on Weyerhaeuser’s BC coastal tenures (Bunnell

et al. 1998). Nevertheless, monitoring indicator species will

help us assess whether or not our strategies for leaving representative unmanaged areas and habitat structures actually

result in productive populations of forest-dwelling species.

Informative focal species are forest-dwelling, sensitive to

58
forest practices, practical to monitor, and provide information that can guide management. Pilot studies in the first 5

years have included birds, vascular plants, bryophytes and

lichens, mycorrhizal fungi, amphibians (frogs and salamanders), squirrels, terrestrial gastropods (slugs and snails) and

carabid beetles. Pre- and post-harvest monitoring is occurring for some of these species on VRAM experiments;

others are being evaluated in operational cutblocks (table 1).

Executive summaries of species pilot studies and a series

of technical project summaries describing objectives and

methodology can be found on the Coastal Forest Strategy

website (www.forestry.ubc.ca/conservation/forest_strategy). 

Growth and Yield Monitoring

The company’s growth and yield program is establishing permanent plots within VRAM areas. In each treatment,

sector plots were established to collect growth data for both

the leave trees and regenerating trees (planted and natural).

Care has been taken to ensure that the same seed source/

stock types are planted across the whole experiment. The

approach uses a cluster of four sectors radiating from a

central pivot point, the central axes of which are at right

angles (fig. 2). For a 10-percent sample, each sector covers

9 degrees (for a total of 36° out of 360°). To sample a

retained group of trees and the surrounding cut area, sector

plots are located by selecting an arbitrary location within

the group (usually the middle of the group of leave trees),

then orienting the sectors from a random compass bearing.

With this approach, the probability of selecting each tree in

a sample is the same irrespective of the position of the 

chosen pivot point. By orienting the four sectors at right

angles, a balance of aspects are sampled for examining

edge effects. This is, as far as we are aware, a new sampling

system which collects information in an unbiased fashion

from retained groups and surrounding areas, correctly

accounting for edge effects (Iles and Smith 2004). At least

three sets of sector plots are established in each treatment

replicate. A slightly modified approach is taken in clearcut

and uncut areas to reduce sampling effort. The four sector

clusters are collapsed into single 36° sector plots which

are oriented randomly from the centre of randomly selected

points on a 1-ha grid. 

In order to increase our sample size for growth and yield

data and cover more stand conditions than are possible in

the 15 VRAM sites, we are establishing supplemental comparison sites with smaller size requirements, including

mixed group-dispersed retention comparisons. These sites

59

Table 1—Summary of operational and experimental monitoring

Operational Monitoring Experimental

Species group 1999 2000 2001 2002 2003 2004 Monitoring

Birds X X X X X X X

Bryophytes X X

Canopy epiphytes X X X X X

Carabid beetles X X X X X

Frogs and salamanders X X X X X X X

Gastropods X X X X X X

Lichens X

Mycorrhizal fungi X X X X

Squirrels X

Vascular plants X X X X X X X

Figure 2—Layout of sector plots for growth

and yield sampling. The shaded polygon in the

center represents a retention patch. The pivot

point of the four 9-degree sectors is located

near the center of the patch.
are operational cutblocks, but treatments are allocated randomly to portions of the blocks. Four have been established

to date.

Windthrow Monitoring

Variable retention results in an increase in the total

length of forest edge associated with cutblocks, as well 

as greater amounts of dispersed trees; consequently, we

expect to see an increase in the frequency and extent of

windthrow associated with harvesting in wind exposed

areas. Our monitoring strategy is to document the extent of

windthrow associated with VR on operational cutblocks as

well as VRAM sites to gather data to improve cutblock

design and windthrow management. All external edges,

groups and patches, and dispersed trees within a treatment

block are sampled. For external edges and larger groups,

visual estimates of the amount of windthrow and depth of

penetration are recorded the first 25 m into a stand edge.

We chose to use stratified, unequal length plots to improve

sampling efficiency and to ensure that any visible environmental differences that may exert a significant effect on

windthrow response are sampled. Plot boundaries are determined by a change in stand conditions or environmental

attributes such as soil type, slope morphology, surficial

materials and boundary exposure. For small groups and

dispersed trees we obtain a total count the number of standing and windthrown trees. VRAM sites are assessed in year

1, 3 and 5 post-harvest.

RESULTS

To date, four VRAM sites have been logged and four

are scheduled for completion in 2004 (table 2). These sites

cover a range of forest types from 100 m to 700 m elevation and are located on Vancouver Island, the Queen

Charlotte Islands and the BC mainland coast. Half of the

sites underway are in old-growth forests. The remaining

seven VRAM sites are intended to be installed by 2007.

Examples of group retention (fig. 3) and dispersed retention (fig. 4) were the first study areas completed in 2000

and 2001, respectively. 

60

Table 2—Characteristics and schedule for variable retention adaptive management experiments

Elevation Harvest

Comparison Locationa Forest typeb (m) systemc Year

Group NIT – Tsitika R. 1 – HwBaCw 550 Hoe 2001

retention SWT – Goat Isl. 1 – HwBaYc 600 Hoe/Cable 2004 

QCT – Hoodoo 2 – SsHwCw 100 Hoe 2004

Dispersed SWT – Horseshoe 2 – Fd 100 Hoe 2002

retention Lk. 2005+ 

TBA 2005+

TBA

Group size PMT – Cluxewe R. 2 – HwBa 100 Hoe 2002

WIT – Klanawa R. 1 – CwHwBa 300 Cable/Hoe 2005

TBA 2005+

Group NIT – Memekay R. 1 – HwBaCw 700 Hoe 2004

removal QCT – Crease 1 – SsHw 400 Heli 2005

TBA 2005+

Riparian SWT – Lewis L. 2 – FdHw 500 Hoe/Cable 2003

retention NIT – Moakwa Cr. 1 – FdHwCw 450 Hoe 2004

TBA 2005+

a NIT = North Island Timberlands, SWT = Stillwater Timberlands, QCT = Queen Charlotte Timberlands, PMT = Port McNeill 

Timberlands, WIT = West Island Timberlands

b 1 = old growth, 2 = second growth; Hw = western hemlock, Ba = amabilis fir, Cw = western redcedar, Yc = yellow-cedar, 

Fd = Douglas-fir, Ss = Sitka spruce

c Hoe = Excavator forwarding, Cable = grapple yarding, Heli = helicopter yarding
61

Figure 3—Aerial photo of a group retention experiment.

Figure 4—Aerial photo of a dispersed retention experiment.
At this point, we have few results to report from most

established studies except documentation of preharvest

conditions. We expect to obtain some useful results to

inform variable retention practices by the fifth year after

harvesting; however, many aspects of biological monitoring

require longer timeframes for assessment of impacts. Monitoring species and forest structure are expected to provide data

that will improve our habitat supply models (Dunsworth

and Northway 1998). 

Some of the initial findings from post-harvest monitoring include windthrow and forest structure. The group retention VRAM site in the Tsitika River valley experienced what

was estimated as at least a 25-year storm in December 2001,

the second winter after harvesting. Retained patches had

windthrow damage ranging from 0 to 85 percent. As a result

of the random allocation of treatments, the lowest retention

level (10 percent) happened to coincide with the portion of

the block most exposed to winds; consequently, this treatment area sustained the most damage. 

Observations of windthrow throughout the area affected

by the storm showed that damage appeared to have more to

do with where the storm winds touched down than to the

size or design of the block (Rollerson et al. 2002). The pattern of windthrow suggested undulating waves or cells of

very strong winds that touched down periodically as the

storm moved across the landscape. The storm affected ridges

and valley bottoms as well as mid-slope positions. The storm

damaged undeveloped old-growth and older second-growth

stands (i.e., generally over 60 years old), the edges of clearcut and VR blocks, retention within blocks and other natural

stand edges such as stream banks. Recently established

plantations and younger second growth did not appear to

suffer significant damage. Heavily damaged stands were

found adjacent to areas with apparently similar conditions

that were virtually untouched. Windthrow within VR groups

or single tree retention was a relatively small proportion of

the total forest damage caused by this storm. Within individual VR blocks, there was often a higher volume of

windthrow associated with the external block boundary

than with the groups left within the block

After 5 years, we have established structure monitoring

plots in a total of 180 retention blocks, 56 benchmark

(unharvested) sites, 20 blocks with riparian reserves and 9

older clearcuts including VRAM areas. Initial comparisons

have assessed whether retention patches provide similar

levels of habitat elements to those found in unlogged forests.

Overall, retention tended to have lower levels of some

important habitat elements, especially large trees and total

basal area, than benchmark sites in the same biogeoclimatic unit (Huggard 2003). Snag density and basal area were

similar, including size and decay class, for benchmark sites

and retention patches. In some areas, however, tall snags

were less common in retention patches. This tends to occur

because of removal of hazard trees during logging operations. In drier ecosystems, retention tended to have more

deciduous trees and snags than unlogged areas. The volume,

composition and size distribution of coniferous woody debris

tended to be similar for retention patches and unlogged

stands. Although patches had lower canopy closure and

shrub cover in some areas, there were no consistent differences in understory vegetation cover between benchmarks

and retention patches.

SUMMARY AND CONCLUSIONS

Company biologists have formed partnerships with 

academic and government scientists to support the Coast

Forest Strategy. Our AM framework outlines both operational and experimental monitoring activities (Bunnell et

al. 2003). The operational monitoring examines structure,

species presence and absence, forest growth, windthrow

and forest health in current and future VR settings. Representation of ecosystems in unmanaged conditions is also being

examined. The experimental portion of the AM program is

focused on 15 VRAM study areas with comparisons designed

to answer questions on the impacts of the amount, type,

spatial and temporal distribution of retention. 

Pilot studies were used to establish an appropriate sampling design and methodologies. Habitat structure including

snags, coarse woody debris, live trees, and understory vegetation is being assessed in VRAM treatments, VR cutblocks and in unmanaged, benchmark forests. Studies on

several organisms (breeding birds, gastropods, amphibians,

bryophytes, lichens, squirrels, mycorrhizae, and carabid

beetles) have been underway for various lengths of time.

These studies are collecting baseline information to begin

comparisons of the effectiveness of the various types of 

VR for maintaining biological richness. Initial findings

have been used to examine how the results will link to

management practices to strengthen areas that most need

improvement. 

Although use of the VR has become widespread in

coastal BC, there is much we need to know about its potential impacts. Among the silvicultural challenges in implementing the retention system to meet biodiversity goals is

predicting forest growth and inventory and managing future

stand health. Forest managers and the public must seek to

62
balance the benefits and costs as this new approach to silviculture is implemented and tested. Critical to the success of

these new approaches is the design of cutblocks and stand

entries to minimize impacts from wind damage. Losses

from wind are unavoidable; however, the risks and economic impacts can be managed through planned salvage or

retention of downed wood when it meets habitat objectives.

Weyerhaeuser will continue to use both natural regeneration

and planting to achieve diverse and valuable stand composition with the variable retention approach. 

Future challenges include a reduction in our public 

forest landbase as a result of the BC government’s reallocation of tenures, long-term funding commitments, and our

ability to adapt our practices to meet changing goals and

expectations. We have much to learn about forest ecosystems and new management techniques, but with the willingness to change, the open-mindedness to consider a wider

range of forest values, and respect for worker safety we

can leave a legacy in our forests for future generations. 

ACKNOWLEDGMENTS

The authors thank the foresters, forestry engineers and

planners, and forest workers on the BC coast for successfully taking up the challenge to implement variable retention

and to do it safely. We thank the members of Weyerhaeuser’s

Variable Retention and Adaptive Management Working

Groups, and specifically: Fred Bunnell, Laurie Kremsater,

Dave Huggard, Ken Zielke, Bryce Bancroft, Jeff Sandford,

Barb Knight and our enthusiastic field crews.

REFERENCES

Arnott, J.T.; Beese, W.J. 1997. Alternatives to clearcutting 

in B.C. coastal montane forests. The Forestry Chronicle.

73(6): 670-678.

Beese, W.J. 1998. The forest project: charting a new 

course. Association of B.C. Professional Foresters,

Forum. 5(5): 20-22.

Beese, W.J.; Dunsworth, B.G.; Perry, J. 2001. The Forest 

Project: three-year review and update. Journal of

Ecoforestry. 16(4): 10-17.

Beese, W.J.; Dunsworth, B.G.; Zielke, K.; Bancroft, B. 

2003. Maintaining attributes of old-growth forests in

coastal B.C. through variable retention. The Forestry

Chronicle. 79(3): 570-578. 

Bunnell, F.L.; Dunsworth, B.G.; Huggard, D.; Kremsater, 

L.L. 2003. Learning to sustain biological diversity on

Weyerhaeuser’s coastal tenure. Contract report to

Weyerhaeuser, BC Coastal Timberlands. www.forestry.

ubc.ca/conservation/forest_strategy (13 January 2005).

Bunnell, F.L.; Kremsater, L.L.; Boyland, M. 1998. An 

ecological rationale for changing forest management on

MacMillan Bloedel’s forest tenure. Contract report to

MacMillan Bloedel Ltd., p. 281.

Clayoquot Scientific Panel. 1995. Scientific panel for 

sustainable forest practices in Clayoquot Sound. Report

5, Sustainable ecosystem management in Clayoquot

Sound: planning and practices. Victoria, BC. 296 p.

Dunsworth, B.G.; Beese, W.J. 2000. British Columbia, 

Canada: new approaches in managing temperate rainforests. In: Price, M.; Kohler, T.; and Wachs, T., eds.

Mountain forests and sustainable development, mountain agenda. University of Berne, Switzerland: Centre

for Development and Environment, Inst. of Geography:

23-24.

Dunsworth, B.G.; Northway, S.M. 1998. Spatial assessment of habitat supply and harvest values as a means

of evaluating conservation strategies: a case study. In:

Bachmann, P.; Köhl, M.; Päivinen, R., eds. Assessment

of biodiversity for improved forest planning. European

Forest Institute Proceedings No. 18. Dordrecht, The

Netherlands: Kluwer Academic Publishers: 315-329.

Forest Practices Code of British Columbia Act. 1999. 

Operational Planning Regulations. S.B.C., c. 41.

Franklin, J.F.; Berg, D.R.; Thornburgh, D.A.; Tappeiner, 

J.C. 1997. Alternative silvicultural approaches to timber

harvesting: variable retention harvest systems. In: Kohn,

K.A.; Franklin, J.F., eds. Creating a forestry for the 21st

century: the science of ecosystem management.

Washington, DC: Island Press: 111-139.

Helms, J.A. 1998. The dictionary of forestry. Bethesda, 

MA: Society of American Foresters. 210 p.

Huggard, D. 2003. Weyerhaeuser BC variable retention, 

adaptive management program. habitat monitoring 1999

to 2003—summary. Unpublished report prepared for

Weyerhaeuser BC Coastal Group. Nanaimo, BC. On

file with: W.J. Beese, Weyerhaeuser, 65 Front St.,

Nanaimo, BC, V9R 5H9.

63
Iles, K.; Smith, N.J. [N.d]. A new type of sample plot and 

its use in selecting sample trees from “variable retention” clusters. Paper submitted to Forest Science. On

file with: N.J. Smith, Weyerhaeuser, 65 Front St.,

Nanaimo, BC, V9R 5H9.

Kremsater, L.L.; Bunnell, F.L.; Huggard, D.; Dunsworth, 

B.G. 2003. Indicators to assess biological diversity:

Weyerhaeuser’s coastal British Columbia forest project.

The Forestry Chronicle. 79(3): 590-601.

Mitchell, S.J.; Beese, W.J. 2002. The retention system: 

reconciling variable retention with the principles of 

silvicultural systems. The Forestry Chronicle. 

78(3): 397-403.

Rollerson, T.; Beese, W.J.; Peters, C. 2002. Progress report: 

variable retention windthrow monitoring pilot project.

Report for Weyerhaeuser Company Ltd., Nanaimo, BC.

On file with: W.J. Beese, Weyerhaeuser, 65 Front St.,

Nanaimo, BC, V9R 5H9.

64
1 Faculty Research Assistant and 2 Associate Professor, Oregon State University, Department of Forest Science, 321 Richardson Hall, Corvallis, OR 

97331-5752, USA. Email for corresponding author: carrie.berger@oregonstate.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Development of Stand Structure 

in Young Douglas-fir Plantations

Carrie A. Berger1 and Klaus J. Puettmann2

INTRODUCTION

Although a large portion of the western Oregon forests

are now occupied by dense Douglas-fir plantations (Pseudotsuga menziesii (Mirb.) Franco), analysis of early growth

rates in old-growth stands in the Oregon Coast Range indicated that these stands may have initiated at lower densities

than commonly found in current plantations. This implies

that these stands may have never gone through a classic

stem exclusion phase (Poage and Tappeiner 2002, Tappeiner

et al. 1997), and the range of natural variability in western

Oregon forests included open conditions in young stands.

This raises the question whether the current, dense plantations will develop efficiently into forests that provide latesuccessional habitat. Several studies (for examples, see

Monserud 2002) have focused on the later stages of the stem

exclusion phase; this study, therefore, focuses on the regeneration establishment phase to investigate whether undesirable aspects of the stem exclusion phase can be prevented

ABSTRACT

Concerns about a landscape becoming dominated by stands in the stem exclusion phase led to initiation of a structurebased management study. The study documented the development of tree characteristics and understory vegetation, two

aspects considered important for the diversity of plant and wildlife habitat. We measured conditions in 39 Douglas-fir

(Pseudotsuga menziesii (Mirb.) Franco) plantations ranging from 6 to 20 years in three districts in western Oregon. Results

confirmed intuitive trends and quantification indicated that some trends develop earlier than commonly assumed. Tree

growth in young stands was positively related to stand density early on, but this trend reversed fairly quickly. Crown size

was reduced very early in higher density stands and crown recession increased with age. Understory herb cover was reduced

over time, while shrub cover increased. Species compositions were quite complex, with an initial strong presence of invasive species and later dominance of species usually associated with mature forests.There were many exceptions, however,

and early successional species were still present after 20 years. 

KEYWORDS: Density management, stand initiation phase, crown characteristics, understory vegetation.

65

or lessened through density management. The objective of

this study was to characterize development of stand structure

and to explore different pathways to manage young Douglasfir plantations for a combination of older forest structures

and revenue production. 

METHODS

Using a chronosequence approach, we selected 39

Douglas-fir plantations from 6 to 20 years in three Oregon

Department of Forestry (ODF) districts (Astoria, Forest

Grove, and Philomath) in the Tsuga heterophylla zone

(Franklin and Dyrness 1973) in the middle to northern part

of the Oregon Coast Range. For a more detailed description, see Puettmann and Berger (in prep.). Three transects

were laid out in each plantation to capture variability. A

transect typically consisted of three circular plots (5-m

radius) established at variable distances with similar slope

and aspect, that differed in overstory densities. Overstory
66

densities on each transect included a low (gap, ~1-3 crop

trees/plot), medium (transition or low density, ~3-4 crop

trees/plot), and high (matrix or fully stocked, ~4-6 crop

trees/plot) density condition that were selected by observational assessment of tree densities. Within this constraint, 

a 5-m radius plot was randomly located in each overstory

density condition. Crop tree selection included all planted

trees and naturally regenerated trees that had dominant

positions. 

Tree and crown characteristics and understory vegetation

data were analyzed by using a mixed model that included

basal area, site index (King 1966), and age as main effect

terms (fixed factor), and the interaction between basal area

and age. Plantation identification and transect within plantation identification were random factors. Total basal area

was used because it accounts for the numbers and sizes of

all trees. Prior to analyses, means were calculated for each

tree plot. Percentage of cumulative cover for forbs and

shrubs was calculated by adding up percentage of cover by

individual species to account for multiple layers of species

in a plot. 

RESULTS AND DISCUSSION

Initially crop trees showed better growth in stands with

higher basal areas in all three districts (for example, see

Philomath in fig. 1), although the Forest Grove district

showed no height response. However, density had a negative

effect on diameter at breast height, height growth, and crown

radius in older stands, and the initial growth trend was

reversed before age 20. Crown recession, due to branch

mortality, was evident in the early stages of growth and

increased with age. Higher densities also reduced diameter

and length of the lowest live branch. (Note, a positive relationship between density and diameter and length of lowest

live branch was found in Forest Grove.) Tree size and crown

characteristics, i.e., crown and branch size, are important

stand structural components and early stand management in

dense plantations is crucial to maintain these components.

For example, wider planting spacing or early precommercial

thinnings are necessary to ensure development of large, low

branches that are important habitat component for mosses,

lichens, and other species (McCune et al. 2000). These

trends were independent of site quality.

High overstory densities were indicative of lower forb

and shrub cover in Philomath and Astoria. In both districts,

shrub cover was greater on high quality sites, suggesting

that resource limitations may be responsible for this trend.

Only in Philomoth did shrub cover increase with age (fig. 2).

Conversely, high overstory density stands in Forest Grove

were correlated with low shrub cover with no recovery over

time. Apparently understory conditions in Forest Grove are

Figure 1—Diameter at breast height for the Philomath district as a function of stand basal area.

Initially crop trees showed better growth in stands with higher basal area; however, this trend

was reversed by age 20. Lines represent different ages.
67

influenced by other factors, such as previous weed control

treatments. At this stage in stand development, shrubs and

forb coverage was very stable and did not change over time.

Overall, composition of understory vegetation was quite

variable. We used the criteria as described by Halpern (1989)

to differentiate invasive and residual species. Within both

groups we found species with different response patterns,

from species with slow rates of occupancy (e.g., Agoseris

spp., Cirsium spp., and Rubus leucodermis) to species that

experienced a shift from increasing to decreasing occupancy

(e.g., Rubus parviflorus, Pteridium aquilinum). The same

variability was found for residual species. For example,

Acer circinatum, Berberis nervosa, Corylus cornuta, and

Polystichum munitum were present after the previous harvest

and showed continuous recovery on our study sites and

Figure 2—Forbs (a) and shrubs (b) for the Philomath district as a function of stand basal area.

Higher densities were indicative of lower forb and shrub cover; however, shrub cover increased

with age. Lines represent different ages.
even became dominant features in fairly young stands (>12

years). On the other hand, other residual species (e.g., Rubus

ursinus) were persistent in all cohorts but decreased in

occupancy in the older stands. In addition, invasive and

residual species were all major contributors throughout the

20-year period.

Our results indicated that stand development as characterized by tree characteristics and understory vegetation is

influenced by density early on and is very dynamic in

young plantations. The development of understory vegetation was highly variable and likely a function of preharvest

stand conditions, harvesting damage, invasion, and recovery.

Maintaining or enhancing existing low-density areas in

young plantations may enable diverse within-stand conditions that affect development of stand composition and

ecosystem function while at the same time allowing flexibility in management of high density areas for different

purposes, e.g., timber production. 

AKNOWLEDGMENTS

Dale Anders, Jeff Brandt, Evelyn Hukari, Doug Robin,

and Steve Skinner coordinated the study setup and site

selection. Aaron Berger provided help with the data collection. Statistical support was provided by Manuela Huso

and Shanti Berryman and Liz Cole helped with all aspects

of the study. The project was funded by the Oregon

Department of Forestry and Oregon State University. 

REFERENCES

Franklin, J.F.; Dyrness, C.T. 1973. Natural vegetation of 

Oregon and Washington. Gen. Tech. Rep. PNW-GTR-8.

Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range

Experiment Station. 417 p.

Halpern, C.B. 1989. Early successional patterns of forest 

species: interactions of life history traits and disturbance. Ecology. 70: 704-720.

King, J.E. 1966. Site index curves for Douglas-fir in the 

Pacific Northwest. Forestry Paper 8. Weyerhaeuser

Company, Forestry Research Center. 

McCune, B.; Rosentreter, R.; Ponzetti, J.M.; Shaw, D.C. 

2000. Epiphyte habitats in an old conifer forest in western Washington, U.S.A. Bryologist. 103(3): 417-427.

Monserud, R. 2002. Large-scale management experiments 

in the moist maritime forests of the Pacific Northwest.

Landscape and Urban Planning. 59: 159-180.

Poage, N.J.; Tappeiner, J.C. 2002. Long-term patterns of 

diameter and basal area growth of old-growth Douglasfir trees in western Oregon. Canadian Journal of Forest

Resource. 32: 1232-1243.

Puettmann, K.J.; Berger, C.A. [In prep.]. Development of 

tree and understory vegetation in young Douglas-fir

plantations in western Oregon. Manuscript in review

with Western Journal of Applied Forestry. On file with:

K. Puettmann, Oregon State University, Department of

Forest Science, 321 Richardson Hall, Corvallis, OR

97331-5752, USA.

Tappeiner, J.C.; Huffman, D.; Marshall, D.; Spies, T.A.; 

Bailey, J.D. 1997. Density, ages, and growth rates in

old-growth forests in coastal Oregon. Canadian Journal

of Forest Resource. 27: 638-648.

68
1 Forest Ecologist, Meridian Environmental, Inc. 1900 N. Northlake Way, Suite 211, Seattle, WA 98103, USA. Email: jboyce @meridianenv.com

Balancing Ecosystem Values Proceedings, Regional Experiments

Blending Stand-Level Treatments and Landscape Planning

with Opportunities for Research in a Working Forest

Jeff A. Boyce1

INTRODUCTION

Two contrasting approaches for managing forest stands

on Throne Island in southeast Alaska were developed as part

of the Lab Bay Timber Sale Environmental Impact Statement

(EIS) (USDA FS 1997a). The primary purpose for developing the management plans was to provide timber for the

local economy as allowed under the existing forest plan

(USDA FS 1997b). A secondary purpose was to address the

physical, biological, and social issues concerning timber

harvest on the island.

A conventional harvest plan would develop a log transfer

facility, a road network, and use cable logging systems to

implement clearcut harvest of 2 to 24 ha units. The nonconventional harvest plan proposes harvesting 109 units, each

ABSTRACT

Two contrasting approaches for managing forest stands on Throne Island in southeast Alaska were developed as part 

of the Lab Bay Timber Sale Environmental Impact Statement (EIS) (USDA FS 1997a). The primary purpose for developing

the management plans was to provide timber for the local economy as allowed under the existing forest plan (USDA FS

1997b). A secondary purpose was to address the physical, biological, and social issues concerning timber harvest on the

island.

A conventional harvest plan would develop a log transfer facility, a road network, and use cable logging systems to

clearcut harvest 2 to 24 hectare (ha) units. The nonconventional harvest plan proposes harvesting 109 units, each 0.8 ha in

size, in a scattered, irregular distribution across the productive forest land on the island. Helicopter harvesting techniques

would be used to minimize infrastructure development on the island. This management plan contrasts with a conventional

harvest approach where a network is developed and cable skyline systems are used. A possible benefit for selecting this nonconventional harvest plan includes the opportunity to conduct landscape and stand-level ecological studies within the existing framework and management of a working forest. Research studies on Thorne Island will provide results applicable to

other working forests in southeast Alaska.

KEYWORDS: Southeast Alaska, adaptive management, landscape planning.

69

0.8 ha in size, in a scattered, irregular distribution across

the productive forest land on the island. Helicopter harvesting techniques would be used to minimize infrastructure

development on the island. This management plan contrasts

with a conventional harvest approach where a road network

is developed and cable skyline systems are used.

This paper outlines and compares the differences between

a conventional and nonconventional harvest method by

addressing such issues as proposed harvest (area and volume), proposed road construction, development of log

transfer facilities, economics, and the effects to noncommodity resources. This information was used to select a

harvest design program for the Thorne Island timber sale

project.
PROJECT LOCATION

The Thorne Island project area is located on the Tongass

National Forest in southeast Alaska, approximately 113 km

northwest of Ketchikan. Thorne Island is part of the Alexander

Archipelago, a group of islands composing southeast Alaska

and coastal British Columbia. It is located near the southern

end of the archipelago, east of Prince of Wales Island, one

of the largest islands in the archipelago. A cool, moist maritime climate dominates the region, producing western hemlock (Tsuga heterophylla (Raf.) Sarg.), Sitka spruce (Picea

sitchensis (Bong.) Carr.), and Alaska yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) forest vegetation

types interspersed with nonforested peatlands. The Lab Bay

EIS planning area includes Thorne Island and approximately

81 000 ha of additional forest land at the northern end of

Prince of Wales Island that was evaluated for timber sale

opportunities.

EXISTING CONDITIONS 

ON THORNE ISLAND

Thorne Island is roughly circular in shape and 2952 ha

in size. Geographic information system (GIS) data shows

that 1235 ha of the island are considered suitable for timber

harvest, 11 ha of which have been previously harvested.

There are no roads, log transfer facilities, or other development on the island, and previous timber harvest has been

limited to a few small areas along the shoreline. The island

is southeast of the small community of Whale Pass and is

commonly used by residents for subsistence hunting and

recreation. The perimeter landscape of the island is visible

from recreational and small, commercial marine traffic. The

interior landscape of the island is generally only visible from

the air and may be seen by passengers of float planes 

providing service to the adjacent community.

TIMBER SALE PLANNING

The initial harvest plan for Thorne Island included two

design options: a conventional road and clearcut harvest

unit design, and a nonconventional distributed patch-cut,

helicopter logging design. Table 1 shows summary information for each of the harvest designs.

The conventional harvest design included the development of a log transfer facility on the western shore of the

island and approximately 25 km of new road construction

to access proposed harvest units. Nineteen units would be

harvested with unit sizes ranging from 2 to 24 ha. Cable

yarding systems would be required in most units to move

logs from the stump to the road. A total of 251 ha would be

harvested during the first entry, providing a harvest volume

of 8.9 million board feet. Due to the initial cost of infrastructure development, a greater proportion of volume

would be harvested during the first entry than in subsequent

entries. Four subsequent harvest entries would be planned

over a 135-year period.

The nonconventional harvest design included the proposed harvest of 109 group selection units in a scattered,

irregular distribution across the forested landscape. Each

unit would be 0.8 ha in size and include the retention of

some trees to provide structural diversity over the life of

the new stand. Approximately 3.9 million board feet could

be harvested in the first entry, with subsequent entries

occurring at 15-year intervals over the next 135 years. A

helicopter yarding system would be used to transport logs

from the stump to barges anchored offshore. The development of a log transfer facility and road network would not

be necessary to implement this harvest design.

Timber sale planning on National Forest System land 

is conducted according to the environmental assessment

guidelines of the National Environmental Policy Act (NEPA).

NEPA regulations (40 CFR 1501.7) require the evaluation

and disclosure of the potential effects of implementing a

proposed action, and alternatives to the proposed action, on

the physical, biological, and social resources of the area.

This evaluation is used by Forest Service decisionmakers

to select a preferred project alternative for implementation.

Environmental analysis of the harvest design options for

Thorne Island included an evaluation of the physical and

biological effects, and a comparison of short-term and longterm project costs and benefits. The nonconventional harvest

design was expected to minimize the permanent disturbance of physical resources on the island, and maintain

visual resources, vegetative diversity across the landscape,

wildlife habitat, and existing subsistence values. Economic

and management factors were also considered in determining which harvest design option would be selected in the

Record of Decision for the Lab Bay timber sale EIS project.

Economic concern for the nonconventional harvest plan

focused on the estimated appraised value of the sale and

whether local purchasers would consider the timber sale

economically feasible. Management concern for the nonconventional harvest plan focused on the ability to efficiently

implement the sale layout and harvesting operations.

ECONOMIC EVALUATION

The first measure of economic feasibility of the nonconventional harvest plan was identified during field studies

70
conducted for the conventional harvest plan. The stand

exam showed that Thorne Island had a greater composition

of cedar species than the remaining portion of the Lab Bay

Timber Sale project area. Western redcedar (Thuja plicata

Donn ex D. Don) composition on Thorne Island was estimated at 14 percent whereas the composition of Alaska

yellow-cedar was 49 percent. The higher selling value of

cedar products, compared to other species, would increase

the appraised value of the proposed sale.

The estimated costs of implementing each harvest plan

are shown in table 1. Costs for the initial entry are identified

separately from all subsequent entries to show the influence

of road network development and logging systems on the

cost of each harvest plan. Costs are estimated for all entries

occurring over a 150-year period, resulting in the harvest

of approximately 40 million board feet. The total revenue

associated with each plan is assumed to be relatively similar, with differences only in the timing of the revenue stream.

Over the entire rotation period, the cost of the nonconventional harvest plan will exceed the conventional harvest

plan by approximately $4.0 million. Assuming that Forest

Service decisionmakers select the nonconventional harvest

plan as a result of the environmental assessment and public

involvement process, the difference in total cost between

the two plans represents the public value of the noncommodity amenities and uses of Thorne Island.

Figure 1 shows the historical market cycle for a composite index of 1000 board feet of wood products sold on

the Tongass National Forest and the discounted value of

the bid price for the nonconventional harvest plan. The

composite index is based on the weighted average species

composition present on Thorne Island and, therefore, represents the estimated value of the products that could be produced from the timber on Thorne Island. The discounted

bid value is based on the purchasers competitive bid price

for the nonconventional harvest plan. The bid value is discounted back through the historical value of the composite

index. This figure shows that through most of the recent

wood products market cycle, the purchase price of the nonconventional harvest plan is lower than the composite market index value on many occasions. This indicates that there

are opportunities for positive economic returns available 

to purchasers of timber sales with nonconventional harvest

designs during part of the market cycle. Timber sales prepared following nonconventional harvest designs are not

fundamentally uneconomical because of their higher costs;

71

Table 1—Comparison of harvest plan attributes and costs

First entry Conventional Nonconventional 

harvest design harvest design

Quantities

Proposed harvest (ha) 251 88

Proposed harvest volume (mbf) 8,961 3,922

Proposed road construction (km) 25 0

Number of log transfer facilities 1 0

Total cost/MBF $427 $380

Subsequent entries 4 additional entries 9 additional entries

over a 135-year period over a 135-year period

Quantities

Total proposed harvest (ha) 718 794

Total proposed harvest volume (mbf) 31,914 35,298

Total proposed road construction (km) 14.5 0

Proposed road reconstruction (km/entry) 18 0

Number of log transfer facilities 0 0

Total cost/mbf $222 $380

Total costs over a 150-year rotation (in constant dollars)

Total cost $10,910,561 $14,903,600 

Total cost/mbf $267 $380 

mbf = thousand board feet
the break-even value for a purchaser depends on the

species product values in the regional market.

MANAGEMENT EVALUATION

The logistics of implementing the nonconventional harvest plan was a concern for the local forest managers. They

were concerned about potentially higher costs to complete

final sale layout tasks, the standards for documenting the

sale area, and the ability of logging crews to efficiently

find the unit locations. Through discussions between the

local forest managers and the sale planners, techniques were

identified for completing the sale layout tasks efficiently

while providing clear identification of each harvest unit that

would last until logging crews began sawing, possibly several years after the completion of sale layout tasks.

The nonconventional harvest design was selected in 

the final EIS for implementation on the basis of minimizing

the environmental effects of harvest while providing an

economically feasible timber sale for the local economy.

THE EVOLUTION OF A TIMBER SALE

Changes in the Tongass Land Management Plan (USDA

FS 1997b) after completing the initial sale design reduced

the total forest land available for timber harvest on Thorne

Island. Harvest units could no longer be placed within 305 m

of the shoreline, and a small old-growth reserve was created to protect sensitive wildlife habitat. These changes

required the recalculation of the total number of 0.8 ha units

proposed for harvest, and a redistribution of the units to be

harvested. The recalculation of the harvest design allowed

for the placement of 90 harvest units on the island.

The location of the 90 proposed 0.8 ha harvest units

were identified using a GIS automated process. A 0.8 ha

grid coverage was overlaid onto the suitable and available

forest land and used to identify individual units for harvest.

An automated procedure was developed in GIS to select the

proposed harvest units based on the rotation length and the

re-entry interval for the island. The GIS procedure identified every tenth grid square overlaying suitable forest land

72

Figure 1—Historical market cycle (weighted by species composition).
as a harvest unit. Because nonsuitable forest land was

intermingled throughout the island, the visual pattern of

harvest would be represented by a scattered, irregular 

distribution across the landscape.

During final sale layout, minor adjustments were made

to the location of some harvest units to protect previously

unmapped streams. In addition, the old-growth reserve was

expanded to account for the discovery of new nesting and

denning areas for sensitive wildlife species. Ninety harvest

units were delineated on the ground to produce an estimated

harvest of 3.0 million board feet. 

The preparation of the timber sale package resulted in

further adjustments to the selection of units proposed for

harvest. Forest managers anticipated low interest in the sale

due to the reliance on helicopter harvesting techniques.

Changes to the final sale offering were proposed that reduced

the number of harvest units with the longest yarding distances, thereby increasing the logging efficiency and reducing the total logging costs. In addition, individual harvest

units were evaluated for species composition in an effort 

to increase the weighted average value per hectare for the

sale. The timber sale contract was drafted to allow the

retention of western hemlock trees identified during cutting

with a high proportion of decay. These changes would

improve the economic viability of the sale, while increasing

the retention of trees for wildlife habitat and visual screening. In the final sale offering, 55 harvest units remained in

the timber sale area, providing an estimated 1.8 million

board foot harvest.

The Thorne Island timber sale was purchased by a local

forest product manufacturer in the spring of 2004. The contract terms require the completion of the timber harvest by

the fall 2005.

OPPORTUNITIES

Although the selection of harvest units was modified

throughout the timber sale planning and implementation

process to account for environmental factors and economic

conditions, the goal of the nonconventional harvest design

remained constant: provide a feasible timber sale to the local

forest products industry with a minimum of long-term effects

on the environmental and social resources of the island.

The final distribution of harvest units includes a range

of site conditions (e.g., site index, plant association, soil

type, aspect, windthrow risk, etc.) that are represented on

the island. The location of harvest units across the landscape

retained the scattered, irregular distribution of the original

harvest design, although units in the central portion of the

island were dropped from the final sale offering.

The number of harvest units and their distribution across

the landscape provide an opportunity to meet research study

design criteria for replication that is often not available from

conventional harvest practices in a working forest. The

inclusion of replication into the harvest design provides a

unique opportunity for reducing environmental variability

in research studies conducted on the island. Environmental

studies on Thorne Island will contrast with other studies

conducted in areas using conventional road development

and clearcut harvesting practices. Other interesting opportunities discussed for Thorne Island include the completion

of time and production studies to provide additional information regarding the production rates and costs of helicopter

logging systems in southeast Alaska.

CONCLUSION

The development and implementation of the nonconventional timber sale for Thorne Island represents a policy

of adaptive management. This concept developed by Walters

(1986) and discussed by Lee (1993) promotes the identification and implementation of nonconventional management policies as a test against which our current policies

can be compared. An important element of adaptive management is the identification and planning of an alternative

resource management policy, which when implemented

provides a distinct outcome for an alternative management

hypothesis. The monitoring and evaluation associated with

implementing nonconventional management policies contrasts with conventional resource management policies, and

either confirms or denies hypotheses about alternative management policies. The Thorne Island harvest plan includes

the planning elements of adaptive management that will

allow forest managers to obtain a greater understanding

about the management of natural resources on the Tongass

National Forest.

A benefit of implementing the nonconventional harvest

design includes the opportunity to conduct landscape and

stand-level ecological studies within the existing framework and management of a working forest. As additional

studies develop on Thorne Island to monitor the response

of ecological conditions to the nonconventional harvest

design, the adaptive management process will continue.

The information obtained through research studies will provide results applicable to other working forest in southeast

Alaska.

73
The physical characteristics of Thorne Island are well

suited for the nonconventional harvest plan. The circular

configuration of the island and the opportunity to helicopter

yard logs to offshore barges requires minimal infrastructure

development on the island and produces an economically

feasible project. Opportunities may be available in other

areas of the western United States and Canada to design

similar landscape plans to achieve environmental and social

goals. Forested areas along scenic highways or river corridors that have high visual constraints may be candidates

for a similar style of landscape plan. This style of harvest

design provides an opportunity to continue harvest activities

in these areas rather than transferring them to other land use

designations containing prohibitions on harvest.

REFERENCES

Lee, K. 1993. Compass and gyroscope: Integrating science 

and politics for the environment. Island Press.

Washington D.C. 243 p.

National Environmental Policy Act of 1969 [NEPA], as 

amended; August 1975. 42 U.S.C 4321 et seq.

U.S. Department of Agriculture, Forest Service. 1997a. 

Lab Bay Timber Sale Environmental Impact Statement

and Record of Decision. R10-MB-321a. U.S. Department

of Agriculture Forest Service, Tongass National Forest.

Volumes 1 and 2. 465 p. [plus appendices].

U.S. Department of Agriculture, Forest Service. 1997b. 

Tongass Land and Resource Management Plan Revision,

Final Environmental Impact Statement. R10-MB-338.

U.S. Department of Agriculture Forest Service, Tongass

National Forest. 

Walters, C. 1986. Adaptive management of renewable 

resources. New York: Macmillan Publishing Company.

374 p.

74

continue
1 Professor of Forest Land Use Planning, University of Washington, College of Forest Resources, Box 352100, Seattle, WA 98195, USA. 

Email: gbradley@u.washington.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Public Perceptions of Alternative 

Silvicultural Treatments

Gordon A. Bradley1

INTRODUCTION

This paper reports on a collaborative project between the

Washington State Department of Natural Resources (DNR)

and the USDA Forest Service, Pacific Northwest Research

Station (PNW), in cooperation with the University of

Washington College of Forest Resources (UW). The collaborators are conducting a joint study of the silvicultural,

economic, and visual effects of alternative timber harvest

patterns at the Capitol State Forest near Olympia, Washington.

The public perception or visual effects aspect of the study

explores how various visual cues affect public responses 

to alternative timber harvesting patterns.

To obtain as much information as possible at a reasonable cost, color photographs of sites were used to survey

people’s reactions to alternative forest harvest patterns and

the visual and cognitive cues within them. Photos have

been found suitable for comparing the visual attractiveness

ABSTRACT

Visual impacts of alternative timber harvest practices are important to consider when developing timber harvest plans or

undertaking ecosystem management operations. People’s reaction to alternative timber management practices may be related

to their level of confidence in the stewardship capabilities of forest management organizations. Determining visual preferences for alternative timber harvest practices is one way of identifying the visual effects of alternative patterns. Ongoing

work at the Capitol State Forest, located near Olympia, Washington, has provided a comprehensive look at visual preferences for six alternative harvest patterns by various interest groups. These groups include foresters, recreationists, environmentalists, educators, and the general public. Groups tend to share a common preference for patterns showing minimal

disturbance but are significantly different as the intensity of harvest practices increase. Foresters showed higher preferences

for intensive forest management practices, whereas all other groups indicated a lower preference for intensive forest practices. Tree retention, harvest size, and residual material seem to be contributing factors related to preference ratings. 

KEYWORDS: Visual resource management, public perceptions.

75

or suitability of landscapes (Brown and Daniel 1984, Kaplan

and Kaplan 1989). They also are cost effective. This study

captures foreground, middle, and background views. 

PREVIOUS FINDINGS

In the context of forest aesthetics, research studies on

visual preference generally show that people agree on what

makes for an aesthetically pleasing landscape and which

modifications create negative visual impacts. Overall, people

tend to prefer landscapes that retain more standing green

trees and that minimize the amount of residual material

such as stumps and brush (Brown and Daniel 1984, Ribe

1989). Many studies have found that a sense of order is

preferred in the landscape as indicated by high ratings for

park-like settings, large trees, and landscapes that appear

“natural.” Ground cover and a mix of vegetation are generally preferred over bare soil and a uniform stand of trees

(Bacon 1995, British Columbia Ministry of Forests 1981
and 1994, Brown and Daniel 1984, Ribe 1989, Ulrich 1986).

The time since initial harvest is also an important factor in

determining visual preference. Over time, preference ratings

improve for sites that have been intensively managed, and

the differences among sites with various silvicultural treatments diminish (Shelby et al. 2003). For many people, preferences for forest scenes rise and fall in a similar pattern,

but preferences for certain scenes may differ based on their

relationship with the landscape. The findings of empirical

research have been incorporated into numerous texts, manuals, and guides that are used by various natural resource

management agencies and professional organizations (Bradley

1996; Forestry Authority 1994; Lucas 1991; Northeast

Regional Agricultural Engineering Service 1993; USDA

FS 1974, 1980).

BLUE RIDGE STUDY

Work on the Blue Ridge study began prior to the actual

harvest of trees. Prior to harvesting, a complete set of onsite

photographs was taken in July 1997 from plot center markers on all plots established by the PNW Research Station,

Olympia. After the research plots were harvested, photographs were taken during spring of each subsequent year

through 2004. 

Photographs were taken at the same location and at 

the same general time of year to control for seasonal and

weather variation in the landscape. Photographs were taken

on sunny days in spring, after deciduous trees had leafed

out, to minimize the factors that may influence preference

ratings such as light angle, fall color, snow, or bare trees.

Also, when taking photos, an attempt was made to capture

the essence of the scene, avoiding features of the landscape

that might otherwise cause a person to give a low rating on

the preference survey. 

Survey Development

The survey was printed in a 22 by 28 cm (8.5 by 11 in) 

format with an explanatory letter indicating the purpose of

the research and assuring confidentiality for subjects if they

responded to the survey. The survey was printed with a

postage-paid imprint and return address on the back cover

so that when the survey was completed, it could be easily

returned to the University of Washington.

The survey contained 30 color photographs depicting

the six treatment plots in the study. For each plot, 5 photos

representing different views of the treatment and varying

amounts of green-up (i.e., time since harvest) were selected.

The order of the photos was randomized. For each photo,

respondents were asked to indicate how much they liked

each scene. A scale of 1 = “not at all,” 3 = “somewhat,”

and 5 = “very much” was used for the preference rating.

For 10 photographs, representing scenes from each plot,

the survey requested additional information regarding why

the respondents rated the scene the way they did.

In addition to the photo portion of the survey, respondents

completed 4 pages of questions regarding knowledge and

attitudes about various aspects of forest management; confidence in different forest management organizations to

manage forests; and demographic information including

current residence, where he or she grew up, and his or her

affiliations with natural resource or environmental organizations

Survey Administration

Selected groups of people were asked to participate in

the study. These groups included educators, foresters, environmentalists, recreationists, and the general public. Those

sampled in the educator category were identified from a

mailing list provided by the Office of the Superintendent 

of Public Instruction in Olympia. Foresters were sampled

from a western Washington Society of American Foresters

chapter. Environmentalists were represented by the Sierra

Club. Recreationists included individuals from the Issaquah

Alps Trails Club and other recreation groups who regularly

use Capitol Forest. The Capitol Forest recreation group

names were provided by the DNR. Finally, the general

public consisted of individuals from both rural and urban

addresses in western Washington. Approximately 750 individuals were sent surveys, and 210 responded (about 28

percent). Of those who responded, 32 were urban residents,

18 were rural residents, 55 were foresters, 51 were recreationists, 33 were environmentalists, and 16 were educators

(population group for 5 respondents could not be determined). Although the above categories are not mutually

exclusive, we stratified the samples by using mailing lists

specific to each group.

FINDINGS

In general, foresters tended to show significantly greater

preference than most other groups for treatments where

tree removal left moderate to large openings (i.e., clearcuts,

patch cuts, and group selection); the difference between

forester response and other groups was most striking for the

clearcut treatment. Most groups tended to show moderate

preference for the two-age treatment, with the exception of

the environmentalists who showed lower preference. All

groups showed high preference for the commercial thin 

and for the control. 

76
IMPLICATIONS

These findings suggest that preferences are generally

similar for different groups of people for most timber harvest

practices. There is a significant difference, however, between

foresters and all other groups regarding the most intensive

timber harvest practices. For example, in this study we found

that a forest scene significantly modified by a timber harvest

is rated higher by a person working in forestry than by a

person who does not work in forestry. This is especially

true for clearcutting. When intensive practices are in full

view of many people other than foresters, there may be less

acceptance of forestry and diminished confidence in the

timber industry as sustainable stewards of the land. This

lack of confidence can result in diminished support for

forestry and may indeed provide the seeds of support for

initiatives that further erode discretion of forest managers

to practice sustainable forestry. Regulations, guidelines,

standards, and lawsuits may all be the result of an increasingly skeptical public.

The management of visual aspects of forestry is one of

several important considerations in practicing sustainable

forestry. Other considerations include economic and engineering efficiency, worker safety, fish and wildlife habitat,

and soil stability. In most cases, visual resource management practices complement these other considerations and

are not advocated to be achieved at the expense of other

aspects of sustainable forestry. The findings from this study

suggest that in visually sensitive landscapes, practices that

result in greater tree retention, smaller openings and rapid

green-up will reduce the visual impact of timber harvest

practices. 

ACKNOWLEDGMENTS

This research is one component of an integrated, longterm research study developed and implemented by the

Silviculture and Forest Models team, Resource Management

and Productivity Program of the USDA Forest Service,

Pacific Northwest Research Station (PNW) and the Washington State Department of Natural Resources to test silvicultural options for managing young-growth forests (Curtis et

al. 2004). Financial support was provided by the PNW

Resource Management and Productivity program and the

Focused Science Delivery program. 

REFERENCES

Bacon, W. 1995. Creating an attractive landscape through 

viewshed management. Journal of Forestry 93(2): 26-28.

Bradley, G.A. 1996. Forest aesthetics: harvest practices in 

visually sensitive areas. Olympia, WA: Washington

Forest Protection Association. 21 p.

British Columbia Ministry of Forests. 1981. Forest landscape handbook. Ministry of Forests. Victoria, BC. 100 p.

British Columbia Ministry of Forests. 1994. A first look at 

visually effective green-up on British Columbia. A public perception study. Victoria, BC 54 p.

Brown, T.; Daniel, T. 1984. Modeling forest scenic beauty: 

concepts and applications to ponderosa pine. Res. Pap.

RM-RP-256. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest 

and Range Experiment Station. 35 p.

Curtis, R.O.; Marshall, D.D.; Bell, D.S., eds. 2004. 

Silvicultural options for young growth Douglas-fir

forests: the Capitol Forest study – establishment and

first results. Gen. Tech. Rep. PNW-GTR-598. Portland,

OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 110 p.

Forestry Authority. 1994. Forest landscape design guidelines. London. 28 p. 

Kaplan, R.; Kaplan, S. 1989. The experience of nature: a 

psychological perspective. Cambridge, MA: Cambridge

University Press. 340 p.

Lucas, W.R. 1991. The design of forest landscapes. Oxford: 

Oxford University Press. 374 p.

Northeast Regional Agricultural Engineering Service. 1993. 

A guide to logging aesthetics: practical tips for loggers,

foresters and landowners. 28 p.

Ribe, R.G. 1989. The aesthetics of forestry: What has 

empirical reference research taught us? Environmental

Management. 13(1): 55-74.

Shelby, B.; Thompson, J.; Brunson, M.; Johnson, R. 2003. 

Changes in scenic quality after harvest: a decade of ratings for six silviculture treatments. Journal of Forestry.

101(2): 30-35.

77
Ulrich, R.S. 1986. Responses to vegetation and landscaping. Landscapes and Urban Planning. 13: 29-44.

U.S. Department of Agriculture, Forest Service. 1974. 

National forest landscape management. In: The visual

management system. Vol. 2. Agric. Handb. No. 462.

Washington, DC: U.S. Department of Agriculture,

Forest Service. 47 p. 

U.S. Department of Agriculture, Forest Service. 1980. 

National forest landscape management. Vol. 2. Chapter

5. Timber. Agric. Handb. 559. Washington, DC: U.S.

Department of Agriculture, Forest Service. 223 p.

78
1 Professor of Soil Science at the Forest Ecosystems Research Center, University of Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany. 

Email for corresponding author: mbredem@gwdg.de

2 Senior Scientist at the Institute of Zoology and Anthropology, Dept. of Ecology, Univ. of Göttingen, Berliner Strasse 28, 37073 Göttingen, Germany.

3 Senior Scientist at the Institute of Soil Science and Forest Nutrition, University of Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany.

Balancing Ecosystem Values Proceedings, Regional Experiments

Integrated, Interdisciplinary Forest Research at Solling, 

Germany—History and Perspectives

Michael Bredemeier,1 Claus Döring,2 and Martin Jansen3

INTRODUCTION

The Solling experimental forest is one of the longest, continuously running studies of its kind worldwide (Ellenberg

1972, Ellenberg et al. 1986, Jansen and Bredemeier 2004).

Results from integrated forest ecosystem research conducted

in the Solling mountain area in central Germany are widely

recognized and have stimulated forest monitoring and

research methodology worldwide. The data sets from Solling

are, in many cases, unique with respect to the duration of

measurements and comprehensiveness of parameters investigated. Research at Solling began almost four decades ago;

in the intervening years, ideas, scopes of management, and

paradigms have evolved.

We describe the history of integrated experimental forest

research at Solling and discuss some of the prominent

results. The objective of this historical description is to

demonstrate the evolution of ideas and intentions in forest

ecosystems research that has occurred over the last 40 years.

ABSTRACT

The Solling experimental forest is one of the longest, continuously running studies of its kind worldwide. Initially, the

scientific approach at the long-term research plots in the mature pure beech (Fagus silvatica) and spruce (Picea abies) stands

was measuring ambient matter and energy transfers at the forest-ecosystem level. Roof experiments were another phase of

this forest ecosystem research, comprising experimental manipulation of hydrological and biogeochemical fluxes. In the third

phase, a landscape approach was chosen to improve the spatial database for regional forest stands and to integrate ecological

and economical information for new concepts of sustainable forest management.

KEYWORDS: Forest ecosystems, long-term research, evolution of methods.

79

LOCATION 

Solling is a low mountain range emerging south of 

the Pleistocene northern German flat plains with elevation

ranging from 200 m to 500 m. Some small towns are located

in the central mountainous area, and a few small villages

are in the interior, but the population density is very low

compared to urban and industrial areas in Germany. The

forest cover, conversely, is comparatively high, amounting

to 60 percent, or 44 000 ha out of 74 000 ha total area.

Solling is a typical “cultural landscape” where the land

has been utilized for centuries in many different ways (NFP

1996). Numerous rural settlements established in the

medieval period were later abandoned in times of plague

and famine and were subsequently covered again by forest.

In later times, when the human population grew again and

primeval industries emerged, human over-exploitation and

livestock degraded the forest in the Solling mountains, and

open, over-aged forests or degraded heathlands dominated
the landscape (Brodhage 1999). In the past two centuries,

the forests at Solling and in other parts of Germany regenerated under scientifically based forest management. Many

of the forests created by these new methods, however, were

often conifer plantations—very different from the primary

natural state. This development is typical of many other

regions and landscapes in Germany. Forest ecosystem

research at Solling started in the early 1960s as part of the

International Biological Programme (IBP) when ecosystems

representative of the different biomes of the world were

selected for investigation (Ellenberg 1972, Ellenberg et al.

1986). A mature pure beech (Fagus silvatica) forest on the

high Solling plateau at about 500 m elevation was chosen

to represent the typical Luzulo-fagetum of the temperate

humid environment at lower elevations and under naturally

oligotrophic site conditions. Shortly after installing the

beech site, a neighboring mature Norway spruce (Picea

abies, ca. 100 years in 1975) plantation forest was equipped

in the same manner for comparing measurements. 

RESEARCH PHASE 1: MEASUREMENT

AND OBSERVATION

Initially, the scientific approach at the long-term research

plots in the mature pure beech and spruce stands was measuring ambient matter and energy transfers at the forestecosystem level. In the 1960s, when the measurements

started, this methodology was absolutely novel. Now, nearly

40 years later, the same methods are used in routine monitoring of forest ecosystems in many countries worldwide,

e.g., the European Level-II monitoring network of forests

in the International Cooperative Programme 

For measurement of liquid phase fluxes, precipitation

collectors were installed inside and outside the forest, and

porous suction cups or plate lysimeters were embedded in

the soil at various depths. Litterfall was sampled and chemically analyzed and repeated soil and humus layer inventories

were performed. The combined result of all measurements

was a complete input-output budget of all biologically

important chemical constituents. 

The first results from the biogeochemical flux investigations were a surprise to the scientists at that time. Instead

of the expected pristine environmental conditions in a remote

forest landscape, the analyses of throughfall and soil solution revealed that these media were highly acidic. Furthermore, when compared to precipitation on open land, a large

surplus of acidity and pollutants in throughfall and beech

stemflow was detected, indicating a high filtering efficiency

of the forest vegetation surfaces for air pollutants. This, in

turn, increased the input of these constituents to the forest

soil.

A hypothesis was put forward postulating the destabilization of forest ecosystems on naturally poor soil substrates,

as in Solling, because of excessive acidification of the soil.

This hypothesis was questioned and criticized at first, but

during the 1980s, when large-scale forest damage spread

over several regions of Germany, it became the basis of

extensive research on forest decline.

There was much concern about acid rain and its effects

on forests in Germany. This concern led to air pollution

legislation, which was quite effective in reducing sulfur

inputs (fig. 1).

Nitrogen loads to the forests, however, could not be

controlled with the same efficiency (non-point source pollution); they remained comparatively high and thus still

contribute to eutrophication of forest soils and waters. 

RESEARCH PHASE 2: EXPERIMENTAL

ECOSYSTEM MANIPULATION 

Roof experiments were another phase of forest ecosystem research, comprising experimental manipulation of

hydrological and biogeochemical fluxes. The roof facility

at Solling, installed between 1990 and 1991, consists of

three roofs, 300 m2 surface area each, underneath the

canopy of a pure Norway spruce stand. The roofs are covered with plates of highly transparent polycarbonate. All

throughfall reaching the roof surfaces is collected in a central facility and then redistributed to the plots by a sprinkler

system. In a clean rain experiment under one of the roofs,

the water is deionized and then resupplied with elements in

concentrations representing an average background (preindustrial) throughfall. 

A highlight of the results from the Solling roof study

was the time-lagged responses of the different ecosystem

components to the decreased soil input fluxes brought

about by clean rain application (Bredemeier et al. 1998a,

Bredemeier et al. 1998b). Soil solution chemistry responded

rapidly to decreased input concentrations, particularly in

the topsoil where less of the previously stored sulphates are

available to counteract the dilution. Decreases in concentrations soon became evident at greater soil depth. Nitrate

leaching ceased completely under reduced N-inputs after

weeks in the top soil and after several months in the deeper

80
soil (fig. 2). These results demonstrate that nitrate leaching

can be efficiently decreased under reduced anthropogenic

atmospheric inputs. The soil solution, a nonbiotic equilibrium

component, responds fastest, whereas the soil solid phase,

due to its high stock of previously stored acidity, changes

much more slowly. The fine roots, in intimate contact with

the soil water, respond to their changed chemical environment with a time lag, which is a common feature in biological systems. Aboveground physiology and growth are

buffered and showed a delayed reaction to these changes

in the root zone. 

81

Figure 1—Long-term observation of sulfate-S and inorganic N fluxes in throughfall of an old

growth Norway spruce stand (“F1” Solling).

Figure 2—Time courses of sulfate-S and nitrate-N concentrations in 10 cm (left) and 100 cm (right) mineral soil depth of the clean rain roof experiment;

vertical reference line indicates start of manipulation, horizontal line nitrate input concentration .
82

RESEARCH PHASE 3: FROM 

PLOT-LEVEL PROCESS STUDIES TO

LANDSCAPE-LEVEL SCENARIOS AND

ASSESSMENTS

Phases 1 and 2 of integrated forest ecosystems research

at Solling were mainly plot experiments. Although these

were necessary to augment our knowledge about ecosystem

processes and the impacts of natural and anthropogenic

disturbances, the high levels of effort and investment connected to these investigations allowed the establishment of

only a few case studies. The third research phase aims to

close the information gap between intensive case studies

and “regular,” managed forest stands and to develop a link

between different spatial scales (Jansen et al. 2004). A landscape approach was chosen to transfer ecological information and to improve the spatial database for regional forest

stands.

The outline of the landscape approach was based on

two elements: a randomized block design and a grid of 100

m x 100 m covering the whole Solling area. The block design

comprised the strata pure beech/mixed beech-spruce/pure

spruce stands and young/intermediate/old forest stands.

Blocks were chosen in the Solling forest landscape based

on geographic information system (GIS) data in such a way

that important site conditions (soil type, elevation, slope,

etc.) were as homogeneous as possible.

Shift of Scope 

In the 1990s, the research focus at Solling shifted from

conducting plot studies to applying the newly gained knowledge regarding forest ecosystems on broader scales. The

aim was to assign ecological properties to the forest stands

of the regional landscape. This stand-scale approach applied

throughout the region and will be the basis for a scientific

assessment of the ongoing forest conversion. 

Ecological Forest Conversion 

For about two decades now, forest conversion with the

aim of more natural forest structures has been happening in

Germany. Besides achieving higher naturalness, the economic sustainability of forestry should be secure. To achieve

these goals, intensively mixed stands of broadleaved and

conifer species were favored (NMLRELV 2004; Otto 1993,

1995).

Employing GIS and codifying the rules for species selection in the lower Saxony state forest conversion program

“LÖWE,” future forest cover and the resulting ecological

and economical scenarios for the entire forest landscape 

of the Solling were calculated (Jansen et al. 2004).

A comparison of the actual stocking with the target state

shows the extent of the initiated forest conversion. For more

than 70 percent of the total forest area, a change of stand

type is planned. This will increase the diversity of tree species

at the stand level. However, neighborhood diversity on the

landscape level will decrease (fig. 3).

Initially, very little was known about the ecological consequences of such a large-scale forest conversion; hopes,

expectations and untested hypotheses dominated the scene.

The recent research activities at Solling (1999-2003) focused

on applying the newly acquired knowledge to actual forest

management, with spatially explicit identification of ecological and economic properties at the management-unit

level.

This effort used an interdisciplinary and synergistic

approach comprised of more than 20 components. It was

based on the different forest functions and focused on the

entire forest landscape, where Solling served as a regional

model. Four classes of forest functions were distinguished

(Beese 1996) and quantitatively assessed: regulation, habitat, economic, and sociocultural functions.

Site Properties Model

Intensive site mapping of large forest areas is an expensive endeavor. But site property data are the most important

ecological information for forest management. Classical

site mapping is static; for instance, it does not consider

changes in soil or climate properties over time. The landscape-oriented research approach at Solling successfully

introduced GIS-based assessment of forest site properties

(Schulz 2003). This laid the foundation for dynamic modeling of sites in the future. This approach also showed that

spatially explicit prediction of important soil chemical indicators and humus layer properties remains difficult for now.

The newly developed site models are also the basis for

spatially explicit, rule-based models of the potential natural

forest cover (Jansen et al. 2002). Owing to local characteristics of species abundances, such models are only valid in

a local forest landscape context. Given that restriction, our

model for the lower Saxony mountain forest land proved 

to be valid.

Properties of Humus Layers in Pure and Mixed Stands

Depth of the humus layer is slightly less in beech stands

compared to mixed and pure spruce stands. The difference

is very small in young stands where humus layers are generally less developed. The depth of the humus layer in

stands of intermediate age (50-80 yr) is similar to that in

the old-growth stands.
83

Figure 3—Current stand types (2001, left) and target stand types (right) according to “LÖWE” 

forest conversion program for the Solling.
The investigations showed that depth of humus layer is

a good indicator for carbon-, nitrogen, sulfur, and phosphorous-stores in the humus, and these elements can be predicted with high confidence. It could be further shown, that

on deeply acidified soils, the admixture of beech to spruce

forest did not improve humus layer quality, as was originally

hypothesized (Jansen et al. 2004).

Consideration of Nutrient Exports

The study at Solling confirmed that harvest exceeding

the stemwood portion of biomass strongly increased exports

of nutrient elements, which are particularly critical on the

poor acidic soil substrates at Solling where nutrient cations

are depleted (Rademacher and Müller-Using 2004). It became

evident that export of harvested beech wood meant a much

larger nutrient export from the forest ecosystem than in the

case of spruce wood (fig. 4). For example, potassium withdrawals resulting from harvest of beech can be two to three

times more than in spruce harvests. A balanced consideration of economical and ecological aspects may lead to management decisions that counteract further nutrient losses,

such as liming, fertilization, or reductions in harvest intensities.

Diversity Patterns

Contrary to initial hypotheses, the plant community in

spruce-beech mixed forests is a combination of the communities found in pure stands of each species. The investigations showed that species numbers in the herb and moss

layer increase in the sequence from quasi-natural pure beech

stands to mixed stands and are largest in the artificial communities of pure Norway spruce forests (Schmidt and

Weckesser 2002, Weckesser 2002). The particularly low

cover and low species counts in the herb layer of the mostly

natural beech stands are a consequence of the low light

levels on the forest floor. The species typical of the natural

beech forest community do not disappear from the spruce

plantation forests, but are reduced in abundance. Structure

and diversity of the herb and shrub layer seems to be more

dependent on local light regimes at ground level than on

tree species composition.

At Solling, where diversity was found to decrease with

increasing naturalness, higher species numbers are interpreted ecologically as an indicator of anthropogenic ecosystem disturbance. The consequence of these results with

respect to modern ecological forest management must be

the support of typical species and structural assemblages in

future. The catch phrase “increase of biodiversity” should

be avoided as an argument for conversion toward more

natural forest in situations such as Solling.

Faunistic Diversity

The patterns of faunistic diversity were more complex

than the floristic patterns, owing to the higher species numbers and the mobility of species (Vollhardt et al. 2003).

Nevertheless, some patterns are quite similar; in the most

natural pure beech forests of Solling, fewer species were

found. Stand structure, as in the case of the flora, seems to

play a more important role than tree species composition.

84

Figure 4—Temporal development of nutrient stocks bound in the biomass (BM) of beech relative

to spruce in a mixed stand of both species at an assumed wood biomass ratio of 1:1 for the two

species.
Structural diversity of the forest stand obviously enhances

species diversity, but “naturalness” of the tree species composition does not.

Only those insect species that damage the forest seemed

less abundant in the intensively (single stemwise) mixed

forests within the Solling study. However, small-scale, patchwise mixtures should also exert a controlling effect on

insect pests.

Naturalness of Tree Species Composition

A central indicator for conservation is “naturalness” of

the tree species composition. The latter can be calculated

for each management unit on the basis of forest inventory

data and maps or models of potential natural forest cover

(Jansen et al. 2002). Weighting of species proportions in

this exercise can either be done by area or by standing 

volume, leading to slightly different results.

Owing to the pronounced dominance of European beech

in the potential natural forest in the Solling, the “naturalness” of stands depends on the proportion of beech in the

stand. When weighting by area, the stands are 50-percent

natural; when weighting by volume, the stands register as

36-percent natural. This indicates that many young beech

trees are already present, but much old-growth spruce with

high standing volume remains. This illustrates that naturalness can be used as a sensitive indicator of silvicultural

options and strategies, which can be easily calculated for

entire forest landscapes, provided that maps of the potential

natural vegetation for an area are available.

Economic Aspects

Statistical analysis of revenues from 1991 to 2000 for

beech and spruce in pure and mixed stands showed that

revenues from beech increased with increasing proportion

of beech. Similarly, revenues from spruce increased with

increasing proportion of spruce. Hence both species reach

maximum specific revenues in their respective pure stands

(fig. 5, Möhring et al. 2004). From an economic perspective, there are no convincing reasons to favor intensively

mixed forests at Solling.

Increasing the proportion of broadleaved species in forest

landscapes like Solling enhances their naturalness. For the

economic success of forestry, however, conifers are an

important component, and will remain so in the future.

CONCLUSION

In forest management of landscapes ecologically similar

to Solling, mosaic-type mixtures (small-scale mixing of

pure stands) are preferable to intensive, single-stem mixtures for ecological forest conversion. Similar results are

reported by Ammer and Utschik (2004). At the landscape

level, various forest functions can be better fulfilled and

optimized with small-scale mixing of pure stands. Intensive

single-stem mixtures turned out to be disadvantageous for

achieving important ecological and economic criteria.

Forest research at Solling illustrates the importance of

long-term, interdisciplinary and integrated research projects.

85

Figure 5—Revenues from forest types pure spruce, mixed with spruce dominating, mixed with beech

dominating, and pure beech for different age classes in the Solling study.

Age class
It demonstrates the worth of such large projects. A framework of well-coordinated interdisciplinary study made these

projects possible and will enable future research that addresses

complex problems such as forest decline or tasks such as

large-scale forest conversion.

A major challenge for future, integrated forest research

will be understanding the response of forests to climatic

change as the chemical environment continues to change.

These issues may call for entirely new approaches to silvicultural planning.

ACKNOWLEDGMENTS 

We are grateful to all organizations that funded research

at Solling over the past four decades, particularly the German

Federal Ministry of Research and Technology (BMBF), the

German Research Foundation (DFG), the European Union’s

Directorate General for Research (EU DG XII), and the

Forest Administration of Lower Saxony. 

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Beese, F.O. 1996. Indikatoren für eine multifunktionelle 

Waldnutzung. Forstw. Cent.bl. 115: 65-79.

Bredemeier, M.; Blanck, K.; Dohrenbusch, A.; Lamersdorf, 

N.; Meyer, A.C.; Murach, D.; Parth, A; Xu, Y.J., 1998a.

The Solling roof project - site characteristics, experiments and results. Forest Ecology and Management.

101: 281-293.

Bredemeier, M.; Blanck, K.; Xu, Y.J.; Tietema, A.; Boxman, 

A.W.; Emmett, B.A.; Moldan, F.; Gundersen, P.; Schleppi,

P.; Wright, R.F., 1998b. Input-output budgets at the

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1 Research Leader, Forest Dynamics, Research Branch, Ministry of Forests, P.O. Box 9519 Stn. Prov. Govt. Victoria, BC V8W 9C2, Canada. 

Email: Louise.deMontigny@gems2.gov.bc.ca

Balancing Ecosystem Values Proceedings, Regional Experiments

Silviculture Treatments for Ecosystem Management 

in the Sayward – The STEMS Experiment

Louise de Montigny1

INTRODUCTION

British Columbia (BC) is a vast land encompassing an

astounding diversity of ecosystems that are rich in natural

resources. The province is covered by 60 million ha of

forests, most (95 percent) of which is owned by the provincial government and, thus, the people of the province. Until

recently, forest management meant timber harvesting and

regeneration. Over the last two decades, however, there has

been a fundamental shift in the way people value the forests

of BC. Nontimber resources, recreation, tourism, water

quality, and wildlife habitat, have been increasingly important and First Nations land claims over much of the province

have yet to be resolved. Throughout the last decade, there

has been an increased use of a diversity of silvicultural

systems to meet multiple resource objectives. How these

silvicultural systems achieve multiple resource objectives

and their sustainability is still in question. The provincial

ABSTRACT

The Sayward Forest in the Campbell River Forest District on eastern Vancouver Island, British Columbia, is a multipleuse forest of 112 000 hectares. The overall management goal is to promote timber harvesting and production in accordance

with principles of integrated resource management that considers all resource values, with stewardship guided by the principles of sustainable use. The design is a replication of the Silviculture Options for Harvesting Young-Growth Production

Forests project developed jointly by the Washington State Department of Natural Resources and the USDA Forest Service,

Pacific Northwest Research Station. Treatments include an extended rotation (unharvested control), extended rotation with

commercial thinning, clearcut with reserves, modified patch cut, group selection, uniform dispersed retention and aggregate

retention. The first replication has been established in the Snowden Demonstration Forest and was harvested in 2001/2002,

a second will be harvested in 2005, and a third is planned. Researchers are monitoring tree growth and stand development,

coarse woody debris, windthrow, harvest cost and productivity, soil disturbance, harvesting damage to residuals, and public

perception of the different treatments. An overview and status of the study and initial results from the first replication is

reported.

KEYWORDS: Silviculture, silvicultural systems, Douglas-fir, western redcedar, British Columbia.

89

government has invested in several excellent silvicultural

systems to examine the long-term effects of these systems.

This paper describes one or these experiments, Silviculture

Treatments for Ecosystem Management in the Sayward, or

STEMS. 

The Sayward Forest

The Sayward Forest, also known as the Sayward Landscape Unit or “the Sayward,” exemplifies the increasing

multiple-use demands on forest resources. The Sayward

covers 112 000 ha in the Campbell River Forest District on

central Vancouver Island. Over the past century, logging or

fire has disturbed most forests in the Sayward. As a result,

63 percent of the area consists primarily of second-growth

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests

between 40 and 80 years old. The few old-growth stands

remaining are fragmented and primarily at higher elevations.

The Sayward is an extremely valuable recreation resource,
with three provincial parks, 67 Forest Service recreation

sites, and numerous hiking and mountain biking trails. The

Sayward also features important wildlife habitats, cultural

and heritage resources, mineral values, a source of domestic water, and is a source of nontimber forest products such

as salal (Gaultheria shallon), mushrooms, and berries. With

a 20- to 50-percent predicted rise in population on eastern

Vancouver Island (Rose 2002), the demand for resources 

in the Sayward is expected to increase dramatically in the

next decade.

The Sayward Landscape Unit Plan (Anon. 2003) has

identified the importance of the multiple resource use in the

Sayward. The overall goal is to promote timber harvesting

and production in accordance with principles of integrated

resource management that considers all resource values,

with stewardship guided by the principle of sustainable use.

The Silviculture Treatments for Ecosystem Management in

the Sayward (STEMS) experiment will help determine how

best to meet the goals and targets set out in the Sayward

Landscape Unit Plan for multiple-use objectives.

METHODS

Experimental Design and Objectives

The STEMS experiment is a rigorously designed, replicated, long-term silvicultural systems experiment that tests

seven treatments: extended rotation (nontreatment control),

extended rotation with commercial thinning, aggregate and

uniform dispersed retention systems, group selection and

modified patch cut systems, and a 10-ha clearcut with

reserves. The first replication (STEMS 1) was established

in the Snowden Demonstration Forest and harvested through

the Small Business Forest Enterprise Program. The second

has been established at Elk Bay and will be harvested by

International Forest Products Ltd. in January 2005. A third

replication is planned for harvesting in 2007 by B.C. Timber

Sales. 

The STEMS experiment is part of a larger study that

includes three replications of six treatments in the Capitol

Forest near Olympia, Washington. This study, titled “Silviculture Options for Harvesting Young-Growth Production

Forests,” for simplicity, will be referred to here as the

Capitol Forest Project. The treatment targets used in the

STEMS project are similar to that of the Capitol Forest

Project (Curtis et al. 2004, Marshall and Curtis 2005), with

two exceptions: the two-aged treatment at the Capitol Forest

is called the uniform dispersed retention treatment at STEMS,

and the STEMS study added a seventh treatment, aggregated

retention, because of its increased use in coastal BC.

The overall goals of the STEMS and Capitol Forest

projects are, within mature second-growth Douglas-fir

stands, to

• Create replicated examples of alternative harvest practices

and silvicultural regimes that can be used as a demonstration area by foresters and planners in ecosystem management,

• Provide quantitative information for evaluation of feasibility and costs of alternative regimes and their long-term

effects on production of timber volumes and values and

other nontimber values, and

• Evaluate the effectiveness of contrasting silvicultural 

systems in reducing environmental and visual impacts of

forestry operations while supplying high timber outputs

over time.

The STEMS experiment consists of three studies with

specific objectives:

• Forest Productivity Study—to quantitatively compare 

forest productivity, including residual trees, regenerating

trees, understory vegetation, light environments, mortality

and windthrow, and coarse woody debris, under contrasting silvicultural systems over an extended period.

• Economics Study—to quantitatively compare timber outputs, production costs, and operational factors associated

with harvesting, including post-harvest residual tree damage, soil disturbance and compaction, and slash loading.

• Public Perception Study—to compare public response to

the various silvicultural treatments at site and landscape

levels.

Site Description

The first replication of the STEMS experiment has been

established at the eastern end of the Snowden Demonstration

Forest which is located in the southern portion of the

Sayward Landscape Unit within the Very Dry Maritime

Coastal Western Hemlock (CWHxm) biogeoclimatic subzone (Green and Klinka 1994). The area was established 

as a demonstration forest in 1987 to raise public awareness

about integrated resource management. The forest in this

area is predominantly Douglas-fir, with a minor component

of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and

western redcedar (Thuja plicata Donn). According to plantation maps, the area was planted in 1946 following clearcut

logging and burning, so average stand age was 55 years in

2001 at the time of harvest.

90
Ecosystem mapping of area identified six site series, the

most common being zonal 01 Douglas-fir–salal (slightly

dry to fresh soil moisture regime (SMR) and very poor to

medium soil nutrient regime (SNR)) and 05 western redcedar–swordfern (slightly dry to fresh SMR and rich to

very rich SNR). Soils were predominantly Ferro-Humic

Podzols with moder humus form, sandy-loam structure,

coarse fragment content averaging about 40 percent, and

depth averaging 50 to 80 cm. The topography of the area is

gently rolling. Large rocky knolls, classified as site series

03 Douglas-fir/shore pine–Cladina (very dry SMR and very

poor to medium SNR) were avoided as much as possible,

but a number of smaller knolls are scattered throughout

treatment unit 5 (patch cut). A root disease survey found

Phellinus weirrii ((Murr.) Gilb.) infections at an overall

infection level of 6.1 percent. An objective of the treatment

unit designation was to include a more or less equal proportion of 01 and 05 sites series and root disease within

each treatment, although this was not always possible. The

patch cut, group selection, and extended rotation treatment

units had a smaller component of 05 site series, and the

patch cut had a higher component of 03 site series.

The total area under prescription is 186.4 ha; the area

within treatment unit boundaries is 139.3 ha (75 percent of

the gross area), and the areas of retention (including internal and external reserves, not including individual tree

reserves) is 52 ha (27 percent of the gross area).

Treatment Description

A summary of the key features of each treatment is

shown in table 1. The treatment unit size varies depending

on the expected variation in stand structure after treatment,

from 11 ha for the clearcut to 36 ha for the patch cut. Stand

structure objectives range from even-aged to two-aged to

multi-aged. Return intervals range from every 10 years for

the multi-aged treatments to 80 years for the even- and

two-aged treatments. The relatively frequent return interval

of 10 years was chosen for the STEMS 1 site because of its

easy access and location within a designated demonstration

forest. The 80-year return interval is based on a biological

rotation age for Douglas-fir on this site. The number of

residual trees targeted in each treatment unit differed: for

the extended rotation, 100 percent of the trees were to be

retained; for the extended rotation with commercial thinning treatment 350 stems per ha of evenly dispersed overstory trees and 150 understory western redcedar were

retained; for the dispersed retention 40 evenly dispersed

stems were retained per ha; in the aggregate retention

residual trees were to be left in groups ranging from 0.02

91

Table 1—Summary description of key features for each treatment

Harvest and Stand Harvested Return

residual structure Treatment opening size interval

Treatment objectives objectives unit size (ha) (ha) (years)

Extended rotation Deferred harvest Even-age 12 0 80

Extended rotation 350 stems per ha Even-age 19 0 20

with commercial 

thinning

Group selection 13 percent area Multi-age 22 0.06 to 0.50 10

cut every 10 years

Patch cut 13 percent area Multi-age 36 0.55 to 2.0 10

cut every 10 years

Uniform dispersed 40 stems per ha Two-age 18 18 80

retention

Aggregate retention 2.6 ha internal, Two-age 26 4.4, 6.4, 11.5 80

5.5 ha riparian 

reserves

Clearcut with All stems Even-age 11 11 80

reserves removed with 0.3 ha

reserve
ha to 1.2 ha and in riparian reserves, up to 5.5 ha. Immature

western redcedar were retained as individuals wherever

possible.

As this was an operational experiment, harvesting was

coordinated by the BC Ministry of Forests, Small Business

Program and was contracted through a public bid process

with different blocks being awarded to different licensees.

Some blocks were further sub-contracted, and all harvesting was completed through summer/fall/winter of 2001 and

early 2002. Trees in all treatments were hand-felled. Loader

forwarding was used as the primary method of extraction

in the dispersed retention, aggregate retention and clearcut

treatments. Cable yarding was used in the extended rotation

with commercial thinning treatment. A combination of

loader forwarding and cable yarding was applied in the

patch cut treatments. Within root rot pockets, the stumps

were to be pulled and inverted by the harvesting contractor

to prevent the subsequent spread of disease. Areas to be

stumped ranged from 1 ha to 7.8 ha (table 2). All treatment

units with a regeneration cut were to be replanted with 1200

stems per ha of PSB 415D 1+0 Douglas-fir in March/April

2002.

The Forest Productivity study is based on repeated

measurements on a grid of 15 to 25 permanent plots per

treatment, maintained for the life of the experiment. Supplementary short-term studies of harvesting costs and visual

impacts are being done in cooperation with other organizations. Details of the methodology and preliminary results

of the forest productivity study are described in de Montigny

(2004). The description of each treatment is summarized in

table 1. The economics study was done by the Forest and

Engineering Research Institute of Canada (FERIC, and

details of the methodology and results are described in Evans

et al. (2003). The public perception study is underway; the

surveys have been completed and the analysis and reporting are in progress by the Forest Practices Branch, BC

Ministry of Forests. 

RESULTS

Pre- and post-treatment statistics are found in table 2.

The treatment units in the southern portion of the experimental area, including the aggregate retention, dispersed

retention, clearcut with reserves, and the extended rotation

with commercial thinning, had significantly higher initial

densities, higher relative density and lower quadratic mean

diameter than other treatment units. This is explained by a

much larger component of western redcedar in the understory, and the average stand ages appear to be different for

the two areas: 60 years in the northern portion and 55 years

in the southern portion. In contrast, the group selection and

patch cut treatments had lowest relative density, and this is

probably a reflection of the slightly higher age and a higher

proportion of 01 and 03 site series with their corresponding

lower site index.

Actual volume removed from each of the treatments

ranged, from 0 percent for the extended rotation, to 53 percent for the extended rotation with commercial thinning, to

100 percent for the clearcut (not including the small reserve).

In the group selection and patch cut treatments, volume

removed ranged from 15 to 19 percent; for the aggregate

and dispersed retention treatments, volume removed ranged

from 83 to 89 percent. 

Extraction costs were highest for the extended rotation

and commercial thinning treatment at $187.52/m3, and

lowest for the clearcut, aggregate retention and dispersed

retention treatments at $3.83./m3, $4.71/m3, and $5.86/m3,

respectively (Evans et al. 2003). The shift-level study showed

that for loader forwarding, the costs did not change considerably with the level of retention. Unfavorable ground conditions in the patch cut treatment required the use of cable

yarding, and thus increased costs.

Tree damage (table 3) was highest in the dispersed

retention block, with 17 percent of all trees showing some

form of damage, primarily caused by forwarding activities.

In the extended rotation with commercial thinning treatment, 15 percent of trees were damaged mostly near the

base of standing trees. This occurred when yarded stems

rubbed against the residual trees. In both treatments the

damage is most likely attributed to inadequate care by the

contractors. The aggregate retention, group selection and

patch cut treatments had the lowest damage at 3, 1, and 

0 percent respectively.

The levels of soil disturbance (table 3) for each treatment were well below the allowable maximum set in the

prescriptions for stratums that were not stumped. The lowest

levels of soil disturbance occurred in areas that were not

stumped within the patch cut, group selection and extended

rotation with commercial thinning treatments (table 3).

Slightly higher levels were found in the treatments that had

loader forwarding activity, including the clearcut, aggregate

retention and dispersed retention blocks. For areas that were

stumped, the level of disturbance ranged from 5.8 to 13.1

percent, which was still very low considering this type of

treatment.

Rates of windthrow (table 3) were highest in the dispersed retention treatment where 46 percent of the residual

92
trees were uprooted and a further 15 percent were left leaning. This excessive loss resulted from two major wind

events in November and December 2001 and again in

December 2002. Trees that had been treated with a spiral

crown pruning (seven trees/ha in which 30 to 50 percent 

of the live crown was removed in a spiral fashion over the

entire live crown) were still standing straight. By comparison, 18 percent of trees in the aggregate retention were

either uprooted or leaning. In the other treatments, the percentage of trees either uprooted or leaning was as follows:

8 percent in the extended rotation with commercial thinning,

4 percent in patch cut, 2 percent in the group selection, and

0.5 percent in the extended rotation. Windthrow around

block boundaries were surveyed and the clearcut with

reserves and the dispersed retention treatment units were

the hardest hit, although all cutblock edges experienced

some windthrow.

Planted seedlings have been very susceptible to elk

browsing. A resident herd of elk is often seen browsing on

seedlings over the winter and early spring. The most heavily

browsed areas occurred in the group selection (40 percent)

93

Table 2—Pre- and post-harvest stand statistics by treatment unit 

Quadratic

Basal Total Merch mean Relative

Density area volume volume diameter density

Treatment (stems/ha) (m2/ha) (m3/ha) (m3/ha) (cm)

Extended Preharvest 607 a 53 ab 610 ab 580 ab 33.1 c 9 ab

rotation Post-harvest 607 53 610 580 33.1 9

Percent 

change 0 0 0 0

Extended Preharvest 1325 b 69 c 712 b 651 c 26.3 ab 14 c

rotation with Post-harvest 636 37 388 359 27.3 7

commercial Percent

thinning change 52 46 46 45

Group selection Preharvest 725 a 48 ab 499 a 465 ab 28.5 bc 9 a

Post-harvest 578 41 405 381 28.5 8

Percent 

change 20 15 19 18

Patch cut Preharvest 763 a 44 a 452 a 418 a 28.0 ab 8 a

Post-harvest 575 36 372 345 27.3 7

Percent 

change 25 18 18 17

Uniform Preharvest 1210 b 55 b 581 ab 530 b 24.6 a 11 b

dispersed Post-harvest 51 6 57 54 38.2 1

retention Percent

change 96 89 90 90

Aggregate Preharvest 1208 b 55 b 571 a 521 b 25.0 a 11 b

retention Post-harvest 247 10 96 86 26.5 4

Percent 

change 80 82 83 83

Clearcut with Preharvest 747 a 53 ab 587 ab 551 ab 30.1 bc 9 ab

reserves Post-harvest 0 0 0 0 0 0

Percent 

change 100 100 100 100

Note: Similar lowercase letters indicate no significant difference between treatments.
and clearcut with reserves (31 percent) treatment units

(table 3). In other treatment units, 14 to 20 percent of planted

seedlings were browsed. 

Initial results of the public perception survey indicate

the public acceptance trends are similar at the landscape

level and the site level—the more a stand has been modified,

the lower the public acceptance rating. The one exception

to the trend was the patch cut, which at the landscape level

appears small, but at the site level appears large and therefore, is viewed more critically.

CONCLUSION

The first of three replications of the Silviculture Treatments for Ecosystem Management in the Sayward (STEMS)

project has been established in the Snowden Demonstration

Forest, located in the southern portion of the Sayward

Landscape Unit on eastern Vancouver Island. The treatments include extended rotation, extended rotation with

commercial thinning, uniform dispersed retention, aggregate

retention, group selection, patch cut (0.5–3 ha) and clearcut

with reserves. These different silvicultural systems and

treatments have created some initial diversity in forest

structure including at least two canopy layers (vertical

structure) and spatial patchiness (horizontal structure). The

stands are dominated by Douglas-fir with a minor component of western hemlock, and many of the treatment units

have a substantial proportion of western redcedar understory.

Ongoing studies with STEMS 1 include studies of forest productivity, including stand development, regeneration,

windthrow and coarse woody debris recruitment; an economic study on harvesting production and impacts of residual tree damage and soil disturbance; and a public perception

study on visual quality and public response. Initial results

are listed below:

• Levels of soil disturbance for stumped and not stumped

areas were within acceptable limits.

• Damage to residual trees appeared highest in commercial

thinning (15 percent) and dispersed retention (17 percent)

treatment units.

• Planted seedlings have been heavily browsed by elk in

the group selection (40 percent) and clearcut (31 percent)

treatments. In other treatment units, 14 to 20 percent of

seedlings were browsed.

• Windthrow losses of 46 percent in the dispersed retention

block was the result of major wind events in the first two

years after harvesting.

94

Table 3—Forest health results

Soil compaction Residual tree damage

In areas In Total Damage Damage Damage Windthrow

Root rot not stumped trees from from from of residual Seedlings

treatment stumped areas damaged falling yarding windfall trees browsed

ha Percent

ERa _ _ _ _ _ _ _ 0.1 _

ER with 

commercial 

thinning _ 0.5 _ 15 12 88 0 4 _

Group 

selection 1.1 0.4 6.6 1 57 14 14 1 40

Patch cut 1 0 5.8 0 100 0 0 1 14

Uniform

dispersed 

retention 1.3 2.7 12.7 17 0 81 19 46 17

Aggregate 

retention 7.8 2 7.3 3 60 30 10 8 20

Clearcut with 

reserves 4.4 0.8 6.6 _ _ _ _ _ 31

a ER = extended rotation
Continued monitoring of the STEMS experiment will

help determine how best to meet the operational goals and

targets set out in the Vancouver Island and Sayward Land

Use Plans for multiple-use objectives. The results of this

experiment will be used to improve forest management

decisionmaking and policies regarding alternatives to

clearcutting.

ACKNOWLEDGMENTS

This experiment and associated studies would not be

possible without the assistance of the B.C. Ministry of

Forests Campbell River Forest District, Forest Practices

Branch, B.C. Timber Sales, the Forest and Engineering

Research Institute of Canada (FERIC), and the USDA

Forest Service, Olympia Forestry Sciences Laboratory.

Funding for this research was provided by the B.C. Ministry

of Forests, B.C. Timber, Forest and Engineering Research

Institute of Canada, Forest Renewal B.C., and B.C. Forest

Innovation Investment.

REFERENCES

Anonymous. 2003. Sayward Landscape Unit Plan. BC 

Ministry of Sustainable Resource Management.

http://srmwww.gov.bc.ca/cr/downloads/srmp/sayward/

Saywardlup.pdf (27 February).

Curtis, R.O.; Marshall, D.; DeBell, D.S., eds. 2004. 

Silvicultural options of young-growth Douglas-fir

forests: the Capitol Forest study – establishment and

first results. Gen. Tech. Rep. PNW-GTR-598. Portland,

OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 110 p.

de Montigny, L.E. 2004. Silviculture treatments for 

ecosystem management in the Sayward (STEMS):

Establishment report for STMES 1, Snowden

Demonstration Forests. Tech. Rep. 017. Victoria, BC:

BC Ministry of Forests, Research Branch. 

Evans, C.; de Montigny, L.; Phillips, E. 2003. Silviculture 

treatments for ecosystem management in the Sayward:

costs and productivity of harvesting. FERIC Advantage.

4 (38).

Green, R.N.; Klinka, K. 1994. A field guide to site identification and interpretation for the Vancouver Forest

Region. Land Management Handbook No. 28. Victoria,

BC: BC Ministry of Forests.

Marshall, D.D.; Curtis, R.O. 2005. Evaluation of silvicultural options for harvesting Douglas-fir young-growth

production forests. In: Peterson, C.E.; Maguire, D., eds.

Balancing ecosystem values: innovative experiments 

for sustainable forestry, proceedings. Gen. Tech.Rep.

Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station.

Rose, C. 2002. Inland island highway reveals wealth of 

opportunities. The Vancouver Sun. 22 March; D1.

95
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1 Research Forester and 2 Forester, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory,

3625 93rd Avenue SW, Olympia, WA 98512-9193, USA. Email for corresponding author: charrington@fs.fed.us

3 Professor, Department of Forestry, Mississippi State University, Mississippi State, MS 39762-9681, USA.

Balancing Ecosystem Values Proceedings, Regional Experiments

Tree and Understory Responses to VariableDensity Thinning in Western Washington

Constance A. Harrington,1 Scott D. Roberts,2 Leslie C. Brodie3

BACKGROUND

The Olympic Habitat Development Study was initiated

in 1994 to evaluate whether variable-density thinning and

management of coarse woody debris could accelerate development of stand structures and plant and animal communities commonly associated with late-successional (or oldgrowth) forests. The study is a joint venture of the Olympic

National Forest and the Pacific Northwest Research Station

(Silviculture and Forest Models team, Resource Management

and Productivity Program). Planning for the study also

involved participants from the University of Washington,

the Washington Department of Natural Resources, the U.S.

Fish and Wildlife Service, and the Washington Department

of Fish and Wildlife. Plot sizes were selected to be large

enough to assess population responses of small mammals.

In addition, the treatments manipulating coarse woody

ABSTRACT

The Olympic Habitat Development Study was initiated in 1994 to evaluate whether active management in 35- to 70-yearold stands could accelerate development of stand structures and plant and animal communities associated with late-successional forests. The study used a variable-density thinning prescription as the main tool to alter stand structure; the prescription

entailed creating gaps and retaining uncut areas, and thinning the remaining forest matrix. We assessed tree damage (primarily windthrow) following thinning, 5-year tree growth, and 3-year vegetation development in control and thinned plots.

Windthrow damage was minor in most plots, occurring primarily in stands with high height-to-diameter ratios and located

in vulnerable topographic positions. Tree growth responded positively to thinning. In addition, tree growth differed spatially—

trees near gaps or along skid trails had better-than-average growth whereas trees near uncut patches had poorer-than-average

growth. Understory vegetation responded to thinning with increased percentage of cover and number of herbaceous species

in thinned areas and in created gaps. Percentage of cover of mosses and liverworts was greatest in undisturbed areas. Early

results indicate that the thinning is operationally feasible and demonstrate that the variable-density thinning increases spatial

heterogeneity within the stands.

KEYWORDS: Tree growth, windthrow, implementation, new techniques.

97

debris were designed specifically to enhance wildlife habitat. Pretreatment surveys of forest-floor small mammals

and arboreal rodents were conducted on all plots (Carey

and Harrington 2001). Post-treatment surveys of small

mammals and arboreal rodents were collected in 2004 in a

subset of the plots but that data, and aspects of the study

related to course woody debris, are not included in this report.

Variable-density thinning is a relatively recent term for

thinning in a nonuniform manner, typically with wildlife

or biodiversity along with traditional economic objectives.

Despite much discussion about the potential of this approach,

as well as the implementation of many projects involving

variable-density thinning in the western United States and

Canada in the last 10 years, little information is available

to managers on stand responses. This report provides early

findings on treatment implementation, logging damage and
windthrow following variable-density thinning, tree growth

in relation to different components of the thinning, and

understory responses. 

METHODS

Study Areas

Eight blocks, 50 to 70 ha in size, were selected in 35- to

70-year-old conifer stands on the Olympic National Forest

in western Washington (fig. 1). Four or five, 6.5- to 9-ha

plots were located in each block such that the plots were

similar in forest condition and were buffered to avoid major

changes in forest cover adjacent to their boundaries. This

report covers responses for four blocks that were treated

between 1997 and 2000.

The four blocks differed physiographically from broad

flat river valleys at low elevations (150 to 300 m) to steep

(>50 percent slope) side hills at higher elevations (580 m)

(table 1). Soils were generally silty or sandy loams. Mean

annual precipitation ranges from 145 to about 320 cm, with

wet winters and dry summers.

98

Figure 1—The eight blocks of the Olympic Habitat Development Study

(tree symbols) and towns (filled circles) in western Washington. The four

locations for which information is presented in this report are represented

by the larger symbols.

Table 1—Site and stand characteristics for the first four blocks thinned in the

Olympic Habitat Development Studya

Annual Primary tree Basal

Block Elevation precipitationb species Stocking area

Trees per

m cm ha m2.ha-1

Bait 190-335 317.5 Western 1095 63

hemlock, 

Douglas-fir

Fresca 150 265 Western 585 63

hemlock, 

Sitka spruce

Rail 275 239 Douglas-fir, 360 46

Western 

hemlock

Snow White 430-580 145-195 Douglas-fir 709 45

a Stand characteristics based on pretreatment surveys.

b Annual precipitation estimates based on the parameter-elevation regressions on independent slopes model 

(PRISM) (U.S. Department of Agriculture Natural Resources Conservation Service et al. 1999).
The blocks differed in initial stand density and basal

area (table 1). Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco) and western hemlock (Tsuga heterophylla (Raf.)

Sarg.) were present on all plot although they were not necessarily the major species; Sitka spruce (Picea sitchensis

(Bong.) Carr.), western redcedar (Thuja plicata Donn ex D.

Don), Pacific silver fir (Abies amabilis Dougl. ex Forbes),

red alder (Alnus rubra Bong.), and big-leaf maple (Acer

macrophyllum Pursh) were locally common but generally

present as minor species or only present at a few plots.

Two blocks (Snow White and Bait) had been planted with

Douglas- fir, but both also had substantial amounts of naturally regenerated western hemlock. One of the blocks (Bait)

had been precommercially thinned, which reduced species

diversity and stocking, but the stands still had fairly high

stocking levels when the study began. Two other blocks

(Snow White and Rail) had been commercially thinned

prior to the implementation of the study, but because the

thinning at Snow White occurred a fairly long time ago (in

the early 1970s), and the sanitation thinning at Rail (in 1986)

removed relatively little basal area, these past activities

were mostly evident only by the presence of old skid trails. 

Treatments

The variable-density thinning prescription designed for

this study called for a series of skips (untreated patches that

were “skipped over” during the thinning operation) and

gaps (stand openings) to be embedded within a thinned

matrix (fig. 2). We call this prescription “thinning with skips

and gaps.” The skips were about 0.1 to 0.3 ha and covered

10 percent of the plot area. Skips were located to preserve as

many large-diameter snags as possible with the proviso that

a maximum of one skip was retained in each quarter of 

the plot (about one per 2.0 ha). Equipment entry was not

allowed in the skips, and gaps were placed at least 20 m

from the skips, thus maintaining the skips as areas within

the stand with minimal disturbance. Gaps were openings

0.04 to 0.05 ha and covered 15 percent of the plot area;

existing gaps associated with pockets of root rot or with

past thinning operations were included in the 15 percent.

All merchantable stems (> 20 cm diameter at breast height

(d.b.h.)) were removed from gaps with the exception of

species of low local abundance (e.g., hardwoods, western

redcedar, and Pacific silver fir). The matrix, covering the

remaining 75 percent of the treatment area, was thinned by

removing 25 percent of the stand basal area, primarily from

the lower crown classes. 

Each block consisted of one uncut control plot and three

or four plots that received the same variable-density thinning prescription but differed in the degree of clumping of

residual logs and slash (see Reutebuch et al. 2002 for details).

Skips, gaps, and trees to be cut were predesignated, subsequently evaluated, and, if necessary, corrected for adherence

to the research prescription. Each block was part of a separate timber sale with additional volume from other stands

outside the study plots included in most of the sales. No

special restrictions (other than no-equipment entry within

skips) were added to the contracts. To facilitate timely implementation of the study, the contracts generally had a 2-year

life; however, depressed timber markets and changes in

environmental regulations, caused thinning to be considerably delayed. The first two blocks (Fresca and Rail) were

thinned in 1997, and the second two blocks (Bait and Snow

White) were thinned in 1999 and 2000. By 2004, six of the

eight study blocks had been thinned. 

Tree and Other Plant Measurements

Eighteen plots were surveyed for logging and wind

damage three winters after thinning was completed (most

windthrow in this area occurs during winter when soils are

saturated and windspeeds are high). Damaged trees were

coded as to type of damage and measured for diameter; these

99

Figure 2—Example of distribution of unthinned skips (dotted areas) and

gaps (diagonal lines) at one of the variably thinned plots in the Olympic

Habitat Development Study.
data along with tree position were then entered into a geographic information system. Damage levels were assessed

in relation to species, topographic position, and location in

relation to components of the thinning treatments. Damage

was also related to pretreatment stand information including basal area and heights of dominant trees. Five-year tree

growth was assessed on 1.44-ha stem-mapped plots. Growth

plots were positioned to include two gaps and all, or portions

of, two skips. Plots were measured during the dormant

season immediately after completion of the thinning, and 

at Fresca and Rail, were measured again 5 years later. All

trees taller than 1.3 m were initially measured and their

location mapped. Due to large numbers of ingrowth trees 

in some areas, a separate subsample of regeneration and

ingrowth was initiated at the 5-year remeasurement. The 

5-year remeasurement data for the two stem-mapped plots

were used to summarize tree growth for the entire stemmapped plot, by species, by treatment components within

the stem-mapped plot (i.e., skips versus thinned areas), and

in relation to distance from skid trails and internal edges

created by the treatments. The 5-year remeasurement of the

stem-mapped plots at Bait and Snow White is scheduled for

winter 2004/2005. Data from the 5-year regeneration and

ingrowth subsampling are available from all four areas.

Pretreatment vegetation surveys included four types of

subplots to accommodate different size categories of vegetation including herbaceous plants, shrubs, seedlings, saplings, overstory trees, mosses, and lichens. Transects 10 m

long were used to record larger understory vegetation

including ferns and nontrailing woody shrubs. Three 0.1-

m2 plots were placed along each transect to assess percentage of cover of smaller plants, mosses, and other features.

Circular plots (5.64- and 2.0-m radius) were used to sample

overstory and understory trees as well as lichens. In total,

39 transects and 78, 0.1-m2 plots were sampled within each

plot. Additional vegetation sampling was conducted within

the stem-mapped plot at each site and purposefully placed

in areas that would be exposed to different treatments.

Post-treatment assessments concentrated on control plots

and the thinned plots containing the stem-mapped areas.

Although fewer total plots were sampled post-treatment,

sampling intensity was increased to capture the anticipated

differentiation of the understory. In addition, sampling

methods were simplified by eliminating measurements

along transects and including all understory components

within the 5.64-m fixed-radius plot. The plot size for cover

assessments for the smaller plants, mosses, and ground features was increased to 0.4 m2. Vegetation data were summarized for the control plot and separately for the three

subtreatment components of the thinned plots (skips, thinned

matrix, and gaps).

RESULTS AND DISCUSSION

Implementation of Variable-Density Thinning

The experimental prescription was implemented with

only minor problems. Variable-density thinning increased

the variability in volume removed per cruise plot and thus

necessitated an increase in the number of cruise plots per

unit area. Stratified sampling partially compensated for this,

but more resources for timber cruising were still needed 

to meet the accuracy standard for lump-sum sales. 

Some loggers were initially ill-informed of contract

requirements and expressed concern about restrictions

associated with the research function or the different type

of prescription. They quickly realized, however, that the

prescription was not difficult to implement. In some areas,

more trees adjacent to the skid trails were removed than

anticipated (as approved by the timber sale administrator to

facilitate operations). In other areas, some marked trees were

left uncut owing to poor markets, but overall, the prescription was implemented as designed.

In a uniform thinning operation, it can be difficult to

fell trees in dense stands; however, the presence of gaps in

the variable-density thinning facilitated the felling of trees

in the gaps and in the thinned matrix. Because the thinning

in the matrix area was a light, low thinning, most of the

larger trees felled were in gaps or removed as part of skid

trail installation. On blocks where ground-based equipment

was used, gaps did receive more equipment traffic than the

thinned matrix because of greater volume removal. In addition, owing to the relative contribution of gaps to the overall volume removed, skid trails were generally routed

through or along the edges of the gaps. Gaps were also 

frequently used as temporary log decking areas. 

No equipment was allowed in the skips which in some

cases forced operators to make sharp turns or reverse logging equipment when reaching the skip boundary. Rutting

caused by the turning of equipment was generally shallow,

becoming inconspicuous within a few years following

thinning.

Damage Associated With Thinning

Logging damage was generally low (table 2). Activities

were halted when soils became too wet to continue without

risking major rutting and compaction, or where specific

equipment or practices were resulting in damage to residual

trees or soil. The usual branch breakage and occasional stem

100
scarring associated with timber falling and extraction were

observed, but few trees were affected overall. Removal of

bark on the lower bole and exposure or damage to shallow

roots were the most common forms of damage observed.

Small trees and shrubs were often pushed over by equipment; a timber sale administrator referred to trees less than

15 cm as “like air” to the loggers, implying that they did

not see them or were not concerned about running over

them. Thus, in some areas with substantial advanced regeneration, many small stems were destroyed in the harvest

operation. This was expected and may have been desirable

in areas that had prolific advanced regeneration of western

hemlock prior to thinning (see below for information on

tree regeneration). Falling branches from overstory trees

also damaged some residual understory and midstory trees,

resulting in top or branch breakage or stem scarring. Large

shrubs were also commonly knocked 

over; some were killed, whereas 

others resprouted. 

Overall, logging damage to the residual

timber and soils was low. Some additional

restrictions are advisable, however, if understory and midstory trees or large shrubs are

desired to meet specific objectives. For example, Wender et al. (2004) suggested that some

large shrubs be protected if fruit production

is critical.

Wind Damage

Wind-related damage differed substantially

from plot to plot across blocks (fig. 3). In

terms of total number of wind-damaged stems

per hectare, only 1 of the 14 thinned plots had

moderate to heavy damage (>50 trees damaged

per hectare), 2 of the thinned plots had minor

to moderate damage (20 to 25 trees per

hectare), and damage at the other 11 thinned plots and

the 4 control plots was very minor (fewer than 5 trees per

hectare). Only two plots (one at Bait and one at Fresca)

had more than 10 trees per hectare greater than 20 cm in

diameter damaged by wind following thinning. Damage

was observed to individual trees as well as groups of trees.

Damage was occasionally clumped as one tree would fall

into a second or third tree and a whole group would come

down. Some smaller trees were bowed over and some trees

snapped off; however, the majority of wind-related damage

was windthrow where all or a portion of the root system

was pulled out of the ground.

Stand height-to-diameter ratio (H:D) (as estimated from

trees measured to calculate site index prior to thinning)

appeared to play a role in predisposing stands to wind damage (table 3). Stands with higher H:D values experienced

the most damage. The timing of the thinning in relation to

major windstorms also appeared to affect severity of damage. One plot at Bait had very little wind damage even

though it had the same H:D ratio (80) and was in a very

similar topographic position as the two plots in the block

that had the most damage. The plot with little damage was

thinned several months after the other plots in the block,

thereby avoiding a major windstorm that occurred while

the other plots were being thinned. The greatest wind damage generally occurred along skid trails and adjacent to gaps

located on ridgetops (Bait) or on a small hill where wind

funneled down a river corridor (Fresca). Most wind-damaged trees were western hemlock, but because we did not

101

Table 2—Logging damage in stem-mapped plots at four

blocks of the Olympic Habitat Development Study

Any Severely 

Block Damage damageda

Percentage of trees

Bait 0.3 0.0

Fresca 4.2 .2

Rail 4.3 .1

Snow White 4.5 1.6

a Severely damaged trees were those with very poor growth potential or

substantially reduced economic value.

Figure 3—Number of windthrown stems per hectare less than or greater than 20 cm for 4

control plots and 14 variably thinned plots in the Olympic Habitat Development Study.

There was 1 control plot and 3 or 4 thinned plots at each block. At Snow White, no windthrow occurred in the control plot.
have detailed information on species occurrence by diameter class on each plot, it was not possible to say whether

hemlock was more susceptible or simply more prevalent. 

Windthrow can be an undesirable side effect of thinning, especially during the first 3 to 5 years following

treatment (Cremer et al. 1982). This study did not include

uniformly thinned stands so we cannot test differences in

windthrow between uniform and nonuniform thinning

treatments—but it does not appear that the variable-density

thinning prescription, by itself, resulted in greater risk of

wind damage. Rather, the factors that commonly predispose

thinned stands to windthrow, such as high H:D ratio and

topographic position, were involved. Results suggest that 

if variable-density thinning is to be imposed on high-risk

stands in the future, windthrow could be minimized by

locating gaps, skid trails, and landings on ridgetop positions where feasible. If that is not possible, gaps could be

eliminated or made smaller during the first entry. Earlier

thinning entries would also reduce risk by lowering H:D

ratios; thus, managers may wish to prioritize stands for earlier thinning if they are in high-risk topographic positions

or have high stem densities likely to result in high H:D

ratios. Although we were somewhat disappointed at the

level of windthrow in the 3 stands that lost more than 10

trees per hectare, even these stands at present retain adequate stocking to meet the original management objectives.

In addition, the greater loading of coarse woody debris and

increased spatial variability of tree distribution resulting

from windthrow are both characteristics consistent with the

overall management objectives for this prescription. 

Tree Growth

Tree growth in the two stem-mapped plots with 5-year

post-treatment data responded positively to the variabledensity thinning with increased diameter growth. Although

this may seem like an obvious conclusion, we were not

sure if these older stands (60+ years old) would respond to

a light thinning in such a short period. In the Fresca block,

tree growth also differed by spatial position–trees near gaps

or along skid trails had better growth than those farther

away, whereas trees near skips had poorer growth than

those farther away (fig. 4). These spatial-position effects

were not significant at Rail (fig. 4). Fresca had no previous

thinning history; however, Rail had received a light thinning 11 years earlier; the recency of the earlier thinning at

Rail may have reduced the treatment response. Certainly

the general patterns of growth response at Rail between

trees greater than or less than 10 m from a gap or skip are

consistent with those observed at Fresca.

Where information is lacking concerning the effects 

of variable-density thinning on tree and stand growth, one

option for managers is to estimate the proportion of stand

area in each treatment category, predict the growth for that

category, and sum the growth for the whole area. This

approach assumes there are no effects associated with

internal edges created by the thinning treatment. Based on

the responses observed at Fresca, we predicted the estimation errors in basal area growth that might occur under three

scenarios of patch sizes and relative stand proportions in

skips or gaps. Given a scenario of 15 percent of the stand

in 0.05-ha gaps and 10 percent of the stand in 0.5 ha skips,

basal area growth within the thinned matrix would be underestimated by 13 percent. In a second scenario, if 25 percent

of the stand was in 0.05-ha gaps and no skips were present,

growth in the thinned matrix would be underestimated by

20 percent. In a third scenario of no gaps and 25 percent 

of the stand in 0.25-ha skips, growth in the thinned matrix

would be overestimated by 5 percent. Thus, the magnitude

of the over- or under-estimation of stand growth will depend

on the spatial extent and distribution of the various thinning components. 

Understory Vegetation

Understory vegetation increased in coverage in almost

all treatments and subtreatments; that is, it increased in all

four blocks where vegetation was measured from year 0 to

3, and again in the two blocks where vegetation as measured from year 3 to 7. The control plot at Bait was the only

plot where coverage declined from year 0 to year 3. Although

differences in sample size, protocols, and personnel may

have increased variability in the vegetation data, we suspect

that the main reason for the general increases in coverage

were overstory crown damage associated with several widespread winter storms in western Washington. These storms

would have broken branches and tops, thus, resulting in

greater light reaching the understory. Four winter storms

were recorded in 1996; this was prior to the implementation

of any of the thinnings but would have affected understory

102

Table 3—Percentage of thinned plots by level of wind

damage and height-to-diameter ratioa

Level of wind damageb

Height-todiameter-ratio >5 trees per ha >20 trees per ha

Percentage of plots with damage

<65 0 0

65-75 17 0

>75 100 67

a Based on trees used to calculate site index prior to thinning.

b Based on 14 thinned plots assessed 3 years after variable-density thinning.
response in the 1997 to 2000 time period (year 0 to year 3

for Fresca and Rail). Three other major snow and ice storms

(in winter and spring 2002 and Jan 2004) could also have

affected results between years 3 and 7 at Fresca and Rail. 

In addition to the apparently weather-associated increases

in understory coverage, the thinning also increased light to

the understory and further enhanced understory development

in the thinned matrix and the gaps (fig. 5). In the future, we

would expect additional increases in the coverage of some

species, especially in the gaps; however, if there is an

extended period without major storms, crown closure will

cause a reduction in percent coverage of some shade-intolerant species.

The pattern of the number of herbaceous species present was similar to the percentage of coverage. That is, there

was a general overall increase from year 0 to 3 and again

from year 3 to 7, and the greatest increase in number of

species occurred within the more disturbed areas of the

thinned plot. For example, the number of herbaceous species

within the control plot at Fresca went from 12 to 14 within

the first 7 years, whereas the number of species in the gaps

of the variable-density thinning increased from 11 to 27

within the same period.

Introduced species were present at all sites and were

more prevalent in the thinned and gap subtreatments than

in the skips or control plots (fig. 6). All of the introduced

species are herbaceous except one, Rubus laciniatus, which

is a shrub. 

The response in the percent coverage of shrubs has been

slower than that of herbaceous species and more variable

over the four sites assessed. Stands with more initial shrub

cover retained higher cover despite whatever damage was

sustained in the winter storms or during the logging process,

and coverage is generally increasing over time. 

Percentage of cover of mosses and liverworts (fig. 7)

was least at the one block measured on the east side of the

peninsula (Snow White), possibly because this block

receives significantly less annual precipitation than the other

three blocks (table 1). Coverage of mosses and liverworts

was greatest at all blocks in the undisturbed areas (control

plots and skips). 

Spatial distribution of herbaceous and shrub coverage

differs in both control and variably thinned plots, but the

rate of differentiation is greater in the thinned plots than in

the control plot (fig. 8). The differentiation in the control

plots reflects the changes in canopy cover (presumably due,

103

Figure 4—Mean basal area growth per tree by category indicating if trees

were within 3 m of a skid trail, or within 10 m of a gap, an unthinned skip,

or the thinned matrix. Paired bars with the same letters did not differ at 

p = 0.05.

Figure 5—Percentage of cover of herbaceous species prior to thining and 

3 and 7 years after thinning by treatment and subtreatment at Fresca.
104

Figure 6—Number of native and introduced herbaceous and shrub species on control (unthinned) and variably thinned

(skip, gap and thinned matrix) plots 3 years after thinning. The total number of species is divided into native and introduced species.

Figure 7—Percentage of cover of moss and liverworts 3 years after thinning by treatment and subtreatment

at four blocks of the Olympic Habitat Development Study.
in part, to crown damage associated with winter storms as

discussed above) whereas the differentiation in the thinned

plots reflects the much greater treatment-imposed variability

in overstory cover.

Numbers of seedlings and saplings taller than 25 cm 

did not follow consistent patterns across the components of

thinning at the four blocks (table 4). This may be due to

natural variation or may reflect different stand histories at

the four blocks. Stand densities at Bait and Fresca were

high prior to thinning; thus, it makes sense that the most

regeneration occurred in either gaps or the thinned matrix.

The 1986 thinning at Rail (11 years prior to the variabledensity thinning) resulted in substantial development of

hemlock seedings throughout the area. Thus, the numbers

for the skips at Rail represent 16 years of development of

regeneration rather than 5. The variable-density thinning at

Rail destroyed much of this advanced regeneration on a

portion of the plot as seen by the much lower numbers for

the gaps and thinned matrix. Snow White had been thinned

between 1971 and 1973, and regeneration that developed

following the earlier thinning had already grown into the

understory and midstory strata and may have effectively

precluded development of additional regeneration. Most

regeneration on all four sites was western hemlock, but

Douglas-fir, western redcedar, Sitka spruce, and cascara

buckthorn (Rhamnus purshiana DC.) were also present. 

MANAGEMENT IMPLICATIONS

There are many possible patterns and approaches to

variable-density thinning prescriptions. The appropriate

approach for use in a particular situation will depend on

stand characteristics, landscape conditions, and management objectives. Thinning with skips and gaps is more

complicated than some other prescriptions because there

are three stand components to monitor. This type of prescription, which includes the maximum range of stand density from openings to unthinned patches, will likely result

in greater heterogeneity than prescriptions that simply vary

thinning intensity. No research is yet available to demonstrate whether the additional complexity is warranted for

specific stand types or management objectives. We do

know, however, that the prescription was easy for loggers

to implement, and it did protect snags and other resources

in the skips.

Early results from this study demonstrate that the variable-density thinning is increasing spatial heterogeneity in

stand density and tree growth as well as heterogeneity in

understory vegetation within the stands. Measurements from

additional blocks as they develop following treatment, and

long-term measurements on all blocks will help determine

how universal the treatment responses are and how long

they last. In addition, as a major rationale for the study was

to examine treatment effects on wildlife habitat, future

surveys should assess wildlife response. (In 2004, 8 of the

original 36 plots were surveyed for the small mammals for

the first time since treatment implementation.)

Future entries into these stands could remove additional

overstory trees or possibly thin the developing understory.

Possible future treatments might include rethinning the

105

Figure 8—Change in distribution of herbaceous and shrub species cover

on a control plot and variably thinned plot 3 to 7 years after treatment at

Fresca.
U.S. Department of Agriculture, Natural Resources 

Conservation Service [NRCS]; National Water and

Climate Center; Oregon State University Spatial

Climate Analysis Service. 1999. Parameter-elevation

regressions on independent slopes model (PRISM).

http://www.wcc.nrcs.usda.gov/water/climate/prism/

prism.html. [November 14, 2003].

Wender, B.W.; Harrington, C.A.; Tappeiner, J.C., II. 2004. 

Flower and fruit production of understory shrubs in

western Washington and Oregon. Northwest Science.

78: 124-140.

106

Table 4—Density of regeneration taller than 25 cm at four

blocks 5 years following variable-density thinning

Treatment

Block Skip Thin Gap mean

Number of trees per ha

Bait 3,272 12,544 10,469 9,524

Fresca 9,903 1,924 17,118 7,357

Rail 149,353 73,021 60,243 90,623

Snow White 4,679 4,297 1,981 3,897

matrix; increasing gap size (for a subset of gaps); releasing

(thinning around) individual overstory, midstory, or understory trees; and augmenting snags and large down wood.

Managers should continue to try new methods, as it is

unlikely a “one-size-fits all” variable-density thinning 

prescription will meet all objectives.

REFERENCES

Carey, A.B.; Harrington, C.A. 2001. Small mammals in 

young forests: implications for management for sustainability. Forest Ecology and Management. 154: 289-309.

Cremer, K.W.; Borough, C.J.; McKinnell, F.H.; Carter, P.R. 

1982. Effects of stocking and thinning on wind damage

in plantations. New Zealand Journal of Forest Science.

12: 244-268.

Reutebuch, S.E.; Harrington,C.A.; DeBell, D.S. Marshall, 

D.M.; Curtis, R.O. 2002. Silvicultural options for multipurpose management of west-side Pacific Northwest

forests. In: Parker, S.; Hummel, S.S., comps. Beyond

2001: a silvicultural odyssey to sustaining terrestrial

and aquatic ecosystems: Proceedings of the 2001

National Silviculture Workshop. Gen. Tech. Rep. 

PNW-GTR-546. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research

Station: 38-46. 
1 Assistant Professor of Forest Ecology and Forestry, Rubenstein School of Environment and Natural Resources, University of Vermont, 343 Aiken Center,

Burlington, VT 05405, USA. Email: William.keeton@uvm.edu

2 Includes all or portions of Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, and Maine in the United States, and Ontario, Quebec,

New Brunswick, and Nova Scotia in Canada. Delineations sometimes also include portions of Pennsylvania and the southern New England states

(Mladenoff and Pastor 1993).

Balancing Ecosystem Values Proceedings, Regional Experiments

Managing for Old-Growth Structure 

in Northern Hardwood Forests

William S. Keeton1

INTRODUCTION

Recent research on sustainable forestry practices in the

northern hardwood region of the United States and Canada2

has focused on “structure-” (Keeton et al. 2001) or “disturbance-based” (Seymour et al. 2002) silvicultural approaches.

ABSTRACT

Recent research in the northeastern United States has focused on “structure-” or “disturbance-based” silviculture. The 

as yet untested hypothesis is that these approaches can sustain a broader array of biodiversity and ecosystem functions than

conventional systems. I am testing this hypothesis using a system that promotes old-growth structural characteristics, termed

“structural complexity enhancement” (SCE). This approach is compared against two conventional, uneven-aged systems

(single-tree selection and group-selection) modified to enhance post-harvest structural retention. The study is replicated at

two mature, northern hardwood forests in Vermont. Manipulations and controls were applied to 2-ha units. The uneven-aged

treatments were replicated twice; the SCE treatment and controls were each replicated four times. Structural objectives

include multi-layered canopies, elevated large snag and downed log densities, variable horizontal density, and reallocation

of basal area to larger diameter classes. The latter objective is achieved by using an unconventional marking guide based on

a rotated sigmoid target diameter distribution, applied as a nonconstant q-factor. The marking guide is also derived from a

target basal area (34 m2/ha) and maximum diameter at breast height (90 cm) indicative of old-growth structure. Crown release

was also used to promote growth in larger trees. Prescriptions for enhancing snag and the density of downed woody debris

are based on stand potential. Forest structure data, including Leaf Area Index (LAI), detailed measurements of individual

trees, and coarse woody debris (snags and downed logs) densities and volumes, have been collected over 2 years pretreatment and 2 years post-treatment. A before/after/control/impact approach was used to analyze these data. Fifty-year simulations of stand development were run in NE-TWIGS, comparing alternate treatments and no-treatment scenarios. Basal area

retention, relative density, canopy closure, LAI retention, and coarse woody debris volumes and densities were significantly

higher under the old-growth silvicultural system. Residual diameter distributions achieved the target rotated sigmoid form.

There will be significant differences in stand development based on the simulation modeling. Late-successional structural

and compositional characteristics will develop to a greater degree under SCE. Large tree (>50 cm d.b.h.) recruitment will be

impaired under the conventional treatments, whereas rates of large-tree development will be significantly accelerated under

SCE.

KEYWORDS: Silviculture, old-growth, stand structure and development, northern hardwoods.

107

Structure-based forestry focuses on the architecture of 

forest stands in aggregate across the landscape or management units. Disturbance-based silviculture attempts to

approximate the range of structural and compositional 

conditions associated with natural disturbance regimes. As

complementary approaches, the shared operational objective
is to explicitly manage for currently under-represented forest

structures and age classes (Franklin et al. 2002) in densities

and spatial configurations more similar to those associated

with natural disturbance and successional dynamics (Seymour

et al. 2002). In the northern forest region, this includes

managing for late-successional structure, which is vastly

under-represented relative to the historical range of variability (Cogbill 2000, Lorimer 2001, Mladenoff and Pastor

1993). 

Particular interest in structure-based silvicultural

approaches has evolved from studies of old-growth northern

hardwood and mixed hardwood-conifer forests. These have

demonstrated the ecological significance of specific structural elements, such as large trees (live and dead), downed

logs, multi-layered canopies, and horizontal variations in

stand density and gap mosaics (Dahir and Lorimer 1996,

McGee et al. 1999, Tyrrell and Crow 1994b). These structures can be limited in forests managed under conventional

even- and uneven-aged systems (McGee et al. 1999). Managing for late-successional forests has the potential to

enhance ecosystem services associated with structural complexity, such as a subset of wildlife habitats, carbon storage, and riparian functions. As a result, managing for oldgrowth structural characteristics, either in part or in full, is

a proposed alternative silvicultural approach (Keddy and

Drummond 1996, Keeton et al. 2001, Mladenoff and Pastor

1993). 

Although there has been much discussion of structurebased forestry in the theoretical literature, there have been

few field trials or experimental tests in northern hardwood

forests. An untested hypothesis is that silvicultural practices

can accelerate rates of late-successional forest stand development (Franklin et al. 2002), promote desired structural

characteristics, and enhance associated ecosystem functions

more than conventional systems. I am testing this hypothesis

using an approach termed “structural complexity enhancement” (SCE) that promotes old-growth structural characteristics while also providing opportunities for timber harvest

(table 1). Structural complexity enhancement is compared

against two conventional uneven-aged systems (single-tree

selection and group-selection) that are advocated regionally

for sustainable forestry (Mladenoff and Pastor 1993, Nyland

1998). Uneven-aged silvicultural systems are sometimes

viewed as more ecologically desirable than even-aged

systems because they maintain continuous forest cover,

although the latter have applications for early-successional

habitat management. Conventional uneven-aged prescriptions employed in this study are modified to increase postharvest structural retention and to represent best available

practices. In addition, group-selection treatments are modified to approximate the average size of canopy opening

associated with fine-scale natural disturbance events in

New England, based on the findings of Seymour et al. (2002).

The objectives for SCE are based on previous research

describing old-growth northern hardwood and mixed northern hardwood-conifer forests (Goodburn and Lorimer 1998;

Gore and Patterson 1985; McGee et al. 1999; Tyrrell and

Crow 1994a, 1994b; Woods and Cogbill 1994; Ziegler 2000).

They include multi-layered canopies, elevated large snag

and downed log densities, variable horizontal density, and

reallocation of basal area to larger diameter classes. The

latter objective is achieved, in part, by using an unconventional marking guide based on a rotated sigmoid target

diameter distribution. Rotated sigmoid diameter distributions

have been widely discussed in the theoretical literature, but

their silvicultural utility has not been field tested. Sigmoidal

form is one of several possible distributions in eastern oldgrowth forests (Goodburn and Lorimer 1999; Leak 1996,

2002). These differ with disturbance history, species composition, and competitive dynamics. The distribution offers

advantages for late-successional structural management

because it allocates more growing space and basal area (and

thus biomass and structures associated with larger trees) to

larger size classes. I predict that this distribution is sustainable in terms of recruitment, growth, and yield. If so, it

would support O’Hara’s (1998) assertion that there are

naturally occurring alternatives to the negative exponential

or “reverse-J” curve typically used in uneven-aged forestry.

It would also suggest that silviculturalists have greater flexibility in managing stand structure, biodiversity, and other

ecosystem functions in the northern forest region than 

previously recognized. 

METHODS

Experimental Design 

The study is conducted at the Mount Mansfield State

Forest and at the University of Vermont’s Jericho Research

Forest. These are located on the western slopes of the

northern Green Mountain in Vermont. Study areas are

mature, multi-aged, northern hardwood forests with minor

shade-tolerant conifer components. There are three experimental manipulations. The first two are conventional unevenaged systems (single-tree selection and group-selection)

modified to enhance post-harvest structural retention. The

modifications are based on a target residual basal area of

18.4 m2/ha, max. diameter of 60 cm, and q-factor (the ratio

of the number of trees in each successively larger size class)

108
of 1.3. Group-selection cutting patches are each approximately 0.05 ha which results in 8 to 9 groups per treatment

unit. 

The third treatment is structural complexity enhancement (SCE). The marking guide (the number of trees that

must be cut in each size class to achieve the desired postharvest structure) is based on a rotated sigmoid (see Leak

2002) target diameter distribution (number of trees per size

class). This is applied as a nonconstant q-factor: 2.0 in the

smallest sizes classes, 1.1 for medium-sized trees, and 1.3

in the largest size classes. The marking guide is also derived

from a target (desired future condition) basal area (34

m2/ha.) and maximum diameter at breast height (90 cm)

indicative of old-growth structure. Accelerated growth in

larger trees is promoted through full (4- or 3-sided) and

partial (2-sided) crown release. Prescriptions for enhancing

coarse woody debris (CWD) volume and density are based

on stand potential (e.g., preharvest CWD volume) and literature-derived targets. Snags were created by girdling diseased, dying, or poorly formed trees. Pretreatment densities

of low vigor trees were sufficient such that girdling of

healthy trees was not necessary to achieve snag prescriptions. On one SCE unit at each of the two study areas,

downed logs are created by pulling trees over, rather than

felling, to create pits and exposed root wads.

Each of the first two treatments (uneven-aged) is replicated twice at Mount Mansfield; the third (SCE) is replicated

four times, twice at each of the two study areas. Two unmanipulated control units are located at each study area.

Treatment units are 2 ha and separated by 50 m (minimum) unlogged buffers to minimize cross contamination

of treatment effects. Experimental manipulations (i.e. logging) were conducted on frozen ground in winter (January

through February) 2003. 

Data Collection 

There are five, randomly placed, 0.1-ha permanent sampling plots in each treatment unit. Within each plot, all live

and dead trees > 5 cm d.b.h. and > 1.37 m tall were permanently tagged, measured, and recorded by species, diameter, height, and decay stage. Tree heights, height to crown

base, and average crown width on each tagged tree were

measured using an Impulse 200 laser range finder. Downed

log (logs > 10 cm diameter) volume by decay class (1-5)

was estimated using a line intercept method, and densities

were measured across 0.1-ha plots. Leaf Area Index (LAI)

was measured at five points in each plot using a Li-Cor

2000 meter. Two dominant canopy trees per plot were cored

at breast height to allow subsequent laboratory determination of tree age and site index50. Two years of pretreatment

and 2 years of post-treatment data collection have been

completed. 

Data Analysis 

The Northeast Decision Model (NED) (Simpson et al.

1996) was used to generate stand inventory metrics based

on pre- and post-harvest sample data. NED data were

exported to NED-SIPS (Stand Inventory and Processing

System) for stand development simulation using the NETWIGS model (northeastern U.S. variant of TWIGS), an

109

Table 1—Structural objectives and the corresponding silvicultural techniques used to promote

those attributes in structural complexity enhancement

Structural objective Silvicultural technique

Multi-layered canopy • Single tree selection using a target diameter distribution

• Release advanced regeneration

• Establish new cohort

Elevated large snag densities • Girdling of selected medium to large sized, low vigor trees

Elevated downed woody debris • Felling and leaving, or

densities and volume • Pulling over and leaving

Variable horizontal density • Harvest trees clustered around “release trees”

• Variable-density marking

Reallocation of basal area to larger • Rotated sigmoid diameter distribution 

diameter classes • High target basal area

• Maximum target tree size set at 90 cm d.b.h. 

Accelerated growth in largest trees • Full and partial crown release of largest, healthiest trees
individual tree-based, distance-dependent stand growth

simulator (Hilt and Teck 1989). Fifty-year projections of

stand development were run for each treatment unit, including controls, using both pre- and post-harvest scenarios.

Cumulative basal area increment (CBAI) was calculated

for each simulation run at 5-year intervals. Projections

were normalized by calculating the differences in CBAI

between no-harvest and harvest scenarios at each time step.

The Kolmogorov-Smirnov two-sample goodness of fit test

was used to test for differences between treatment groups

along mean CBAI time series. Single-tree selection and

group-selection treatments were classified as one group

(conventional uneven-aged aged) for the purposes of these

tests. This was appropriate because there were no significant differences among uneven-aged units in residual stand

structure when data were aggregated to the unit scale. The

log-likelihood ratio goodness of fit test (G test) was used 

to examine total CBAI developed after 50 years; response

ratios (treatment vs. no treatment) were compared against a

null ratio (no treatment effect). NE-TWIGS was also used

to predict the number of large trees (two classes: > 50 cm

and > 61 cm d.b.h.) developed after 50 years. Sample data,

including individual tree heights, crown dimensions, and

CWD attributes, were also used as input for 3-dimensional

modeling in the Stand Visualization System (SVS)

(McGaughey 1997). 

A before/after/control/impact (Krebs 1999) statistical

approach was used to compare preharvest and residual

stand structure. Statistical analyses of structural variables

included tests of means (e.g., ANOVA, Bonferroni multiple

comparisons, t tests) and tests of variance (e.g., F tests).

The latter were used to test equal variance assumptions.

For three-way comparisons of residual structure at Mount

Mansfield alone, plots were aggregated by treatment type

rather than experimental unit. The sampling frame was

defined as the continuous population of forest patches rather

than arbitrarily imposed unit delineations (Stehman and

Overton 1996). F tests of variance were used to evaluate

consistency in post-harvest structure among units treated

with the same prescription. To validate the use of plots as

independent samples, spatial autocorrelation tests (Riply

1981) using the Moran coefficient (Moran 1950) were performed on relevant response variables using S-Plus statistical software (Kaluzny et al. 1998). Response data were

sorted by treatment and made spatially explicit using georeferenced plot positions. Spatial autocorrelation results

were cross-checked against empirical variograms produced

in S-Plus.

Diameter distributions (pre- and post-harvest) are a useful indicator that integrates vertical and horizontal structural

responses to treatment. To determine whether SCE successfully shifted diameter distributions toward the target rotated

sigmoid form, pre- and post-harvest and target distributions

were log transformed to enhance sigmoidal tendencies (Leak

2002). Residual distributions were smoothed by using a

Friedman smoothing run in S-Plus software. KolmogorovSmirnov two-sample goodness of fit tests were used to test

for statistically significant differences between transformed

residual and target cumulative frequency distributions. Residual distributions were created by using real (sample) data

for smaller diameter classes (<70 cm d.b.h.) and hypothetical (e.g., future potential) values for larger diameter classes

(>70 cm d.b.h.). The latter borrowed values from the target

distribution. Statistical tests, therefore, evaluated whether

residual distributions achieved that portion of the target

distribution possible given the preharvest structure. 

RESULTS

Residual Stand Structure

Visualizations generated in SVS illustrate the high

degree of structural complexity maintained by both SCE

and single-tree selection (fig. 1). High levels of residual

structure were maintained by all of the experimental treatments, including group selection. However, there were 

distinct differences. Canopy closure was highest for SCE

(mean 77 percent) and lowest for single-tree selection units

(mean 64 percent). These results were statistically significant (P < 0.01). Canopy closure, as expected, was most

variable across group-selection units. Aggregate canopy

closure remained high in group-selection units because 70

to 80 percent of each group-selection unit was unlogged

and thus maintained full preharvest structure. For investigations focused on Mount Mansfield, F tests of variance

showed no significant differences (a = 0.05) in post-harvest

structure between similarly treated units. There was no significant (a = 0.05) spatial autocorrelation among plots sorted

by treatment; a result confirmed by empirical variograms.

Individual plots were determined to be spatially independent

samples based on these results.

There were significant differences (P < 0.001) in LAI

responses among treatments. Single-tree and group selection cuts reduced LAI by 20 and 30 percent respectively.

LAI reductions were lowest in SCE units (9 percent), indicating high retention of foliage bearing tree crowns and

thus, by inference, vertical complexity. LAI was significantly more spatially variable for both SCE (P = 0.031)

and group-selection (P = 0.010) compared to single tree

selection; within-treatment variance was not significantly

different between SCE and group-selection units (P =

0.296). These results are indicative of the high degree of

110
horizontal structural variability expected for group selection. In SCE units, increased horizontal complexity was

achieved through variable-density marking and clustered

harvesting around crown-release trees. 

A significantly higher level of residual basal area was

maintained by SCE compared to either single tree selection

(P = 0.047) or group selection (P = 0.041) units using

aggregated, spatially independent plot data (n = 10 per treatment) for Mount Mansfield only. Post-harvest relative density was also significantly greater in SCE units compared to

single-tree selection (P = 0.013); it was not significantly

greater than group-selection units (P = 0.123). There were

no statistically significant differences (a = 0.05) in variance

within groups of plots aggregated by treatment. This result

held for both pre- and post-harvest structure.

SCE shifted residual diameter distributions to a form

indistinguishable from the target rotated sigmoid form.

There were no statistically significant differences (a = 0.05)

between residual and target distributions for any of the SCE

units based on the goodness of fit test using log transformed

diameter distributions (fig. 2). Future continued reallocations of basal area and stem density into larger size classes,

yielding a rotated sigmoid distribution spanning a full

range of diameter classes, are thus likely.

Crown Release and Vertical Development 

Variable density harvesting resulted in crown release 

for 45 dominant trees per ha on average in SCE units. When

combined with the average pretreatment number (20 per

ha) of large trees (> 50 cm d.b.h.), our future target of 55

large trees per ha is exceeded. The excess provides a margin

111

Figure 1—Output of the Stand Visualization System (SVS) contrasting single-tree selection in unit 4 (above) with structural complexity enhancement (SCE)

in unit 2 (below) at the Mount Mansfield study area. Images of pre- and post-harvest stand structure for 1-ha blocks are shown. Shaded circles represent

tree crowns (with species-specific coloration) seen from a simulated aerial view. Note the high degree of post-harvest structure (e.g., basal area and stem

density), canopy closure, vertical complexity, and downed log densities in the SCE unit. Note the similar, though lower, degree of structural retention in

the single-tree selection unit.
of safety to accommodate canopy mortality. Crown release

is likely to accelerate growth rates in the affected dominant trees by 50 percent or more based on previous modeling (e.g. Singer and Lorimer 1997). Dominant canopy

trees were released across a range of diameter classes

(>25 cm d.b.h.); the majority were fully, rather than partially,

crown released. Crown release also resulted in spatial aggregations of harvested trees, creating canopy openings and

variable tree densities. Elevated light availability associated

with clustered harvesting around crown release trees is

likely to promote vertical differentiation of the canopy

through release and regeneration effects. This will increase

foliage density in the emergent and lower canopy layers

over time.

Coarse Woody Debris Enhancement

Prescriptions to enhance structural complexity resulted

in substantially elevated densities of both downed logs and

standing snags. The structural complexity enhancement

treatments increased CWD densities by 10 boles (> 30 cm

d.b.h.) per ha on average for snags and 12 boles (> 30 cm

d.b.h.) per ha on average for downed logs. Pulling trees

over, in most cases, successfully created large, exposed

root wads and pits. There were statistically significant 

differences (P = 0.002) among treatments with respect to

downed log recruitment effects (fig. 3). Post-harvest

downed log volumes were 140 percent higher on average

than preharvest levels in SCE units. Mean downed log 

volume increased 30 percent in the combined uneven-aged

units, although this effect was not statistically significant

relative to the controls. There were only slight (5-percent

mean) increases in control units due to natural mortality;

volumes declined in some control units. Background

recruitment rates were thus not sufficient to explain SCE

treatment effects. Analyses of downed log decay class 

distributions in SCE units showed, as expected, significant

(P < 0.05) shifts towards less decayed logs due to large

inputs of felled trees. 

112

Figure 2—Preharvest, post-harvest, and target diameter distributions for the four units subject to the structural complexity enhancement treatment, two at

Mount Mansfield (top) and two at the University of Vermont’s Jericho Research Forest (bottom). Log transformed post-harvest and target distributions are

compared (top portion of graphs) by using the Kolmogorov-Smirnov two-sample goodness of fit test. There were no statistically significant differences.

Thus, the post-harvest distributions achieved the target rotated sigmoid distribution.

Dmax= 0.036

Dcrit, 0.05= 0.427

No Sign. Diff.

Dmax= 0.039

Dcrit, 0.05= 0.425

No Sign. Diff.

Dmax= 0.024

Dcrit, 0.05= 0.420

No Sign. Diff.

Dmax= 0.022

Dcrit, 0.05= 0.421

No Sign. Diff.
Projected Stand Development

Stand development projections suggest that total basal

area under SCE will, on average, approach 34 m2/ha after

50 years of development. This is >50 percent higher than

the mean for the conventional uneven-aged units. However,

this difference is attributable to the higher residual basal

area left by SCE. The projections showed no significant

differences in absolute growth rates between treatment

scenarios, as measured by cumulative basal area increment

(CBAI) (fig. 4, top). When projected developed with treatment is normalized to reflect the amount of development

(specific to each unit) that would have been expected with

no treatment, the simulations indicate that CBAI will be

faster under conventional systems (fig. 4, bottom). Both

SCE (P < 0.05) and conventional treatments (P < 0.01) are

projected to significantly accelerate tree growth rates above

that expected with no treatment based on NE-TWIGS modeling. Total projected CBAI after 50 years was 12.5 m2/ha

(no treatment) compared to 28.0 m2/ha (with treatment), on

average, in SCE units. For conventional units, total mean

projected CBAI increased from 1.5 m2/ha (no treatment) 

to 23 m2/ha (with treatment). 

SCE is projected to significantly enhance rates of large

tree recruitment over no-treatment scenarios. There will be

an average of 17 more large trees (> 50 cm d.b.h.) per ha

than there would have been without treatment after 50 years

in SCE units. There will be 29 fewer large trees per ha on

average in the conventional units than would have developed in the absence of timber harvesting (fig. 5). 

DISCUSSION

Silvicultural techniques can be used effectively to promote old-growth structural characteristics in northern hardwood and mixed northern hardwood-conifer forests. Both

the uneven-aged approaches tested and SCE maintain high

levels of post-harvest structure and canopy cover. However,

SCE maintains, enhances, or accelerates development of

CWD, canopy layering, overstory biomass, large tree recruitment, and other structural attributes to a greater degree. The

higher levels of structural retention associated with SCE are

indicative of lower intensity, minimal impact forestry

practices. 

Both SCE and conventional uneven-aged treatments will

result in accelerated tree growth rates according to simulation projections. Because the conventional treatments retained

less basal area, their comparatively higher projected basal

area increment is consistent with previous research on

growth responses to stocking density (Leak et al. 1987).

Note, however, that the NE-TWIGS model is not spatially

113

Figure 3—Downed log response to treatments. Shown are percentage of change from preharvest levels

and absolute change in volume (m3/ha). Error bars are ±1 standard error of the mean. 
effect of SCE is the promotion of large-tree recruitment;

this process is impaired under conventional treatments that

include maximum diameter limits. Projected basal area is

also higher after 50 years of development under SCE due

to elevated post-harvest structural retention. 

Structural complexity enhancement resulted in significantly elevated CWD densities and volumes. However, it

remains uncertain whether this effect will persist until natural

explicit. Inter-stem competition and tree growth rates are

simulated as a function only of total stand stocking (within

size classes) and not the spatial position of individual trees.

The model does not, therefore, capture the effects of crown

release employed in SCE. Because crown release is likely

to significantly increase growth rates in selected dominant

trees (Singer and Lorimer 1997), spatially explicit simulation modeling may result in different, and possibly enhanced,

developmental projections for SCE. Regardless, an important

114

Figure 4—Results of NE-TWIGS stand development modeling. Shown are cumulative basal area increment

(CBAI, live tree) for 50-year projections of post-harvest structure (top) and normalized scenarios (post-harvest

minus preharvest CBAI). Error bars are ±1 standard error of the mean.
recruitment rates increase, or, alternatively, whether CWD

enhancement in mature stands has only transient or shortterm management applications. Although long-term CWD

persistence and accumulation dynamics are uncertain, it is

likely that decay-class distributions will again shift over

time toward better decayed material. This would render

silviculturally-enhanced CWD more biologically available

in habitat and nutrient processes in the future (Goodburn

and Lorimer 1998, Gore and Patterson 1985, Tyrrell and

Crow 1994a). 

SCE may have several useful applications, depending

on economic feasibility, ranging from old-growth restoration, to riparian management, to low-intensity timber management, and late-successional wildlife-habitat enhancement.

Depending on the specific application, SCE could be

employed to varying degrees. For instance, where timber

production is emphasized, a subset of SCE elements might

be used. Other elements might be avoided or employed at 

a lesser intensity. In this scenario, multiple stand entries

would be expected, but late-successional structural development would be lower compared to full SCE implementation. Such an approach, however, would allow forest

managers to build some degree of old-growth associated

structure into actively managed stands, while maintaining

greater flexibility in timber management. Managers of 

115

protected areas, conversely, might choose to employ SCE

more fully. They might enter a stand once or twice, thereafter allowing accelerated successional processes to take

over. The degree of implementation and the number of

stand entries will differ by application. 

Forest managers have the flexibility to manage for a

wide range of structural characteristics and associated ecosystem functions. Uneven-aged systems provide some, but

not all, late-successional structural characteristics, or provide

them to a more limited extent. Residual basal area, maximum diameter, and q-factor can be modified singly or collectively, resulting in greater structural retention. However,

maximum diameter limits significantly retard the potential

for large tree (live and dead) recruitment based on the

results. Stand development is thus continuously truncated

by multiple uneven-aged cutting rotations or entries. The

results show that SCE’s variable q-factor marking guide

can be used to successfully achieve a rotated sigmoid

diameter distribution. Unconventional prescriptive diameter

distributions, such as the rotated sigmoid, combined with

higher levels of residual basal area, very large (or no) maximum diameters, and crown release are other alternatives

for retaining high levels of post-harvest structure and for

accelerating stand development. 

Figure 5—Projected change in large tree densities after 50 years. Values represent the difference between

treatment and no-treatment scenarios. Note the increased recruitment of large trees under SCE versus 

the impairment of large tree recruitment under the conventional uneven-aged treatments.
ACKNOWLEDGMENTS

This research was supported by grants from the USDA

CSREES National Research Initiative, the Vermont Monitoring Cooperative, the Northeastern States Research Cooperative, and the USDA McIntire-Stennis Forest Research

Program. 

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Forest Research. 24: 1672-1683.

Tyrrell, L.E.; Crow, T.R. 1994b. Structural characteristics 

of old-growth hemlock-hardwood forests in relation to

stand age. Ecology. 75: 370-386. 

Woods, K.D.; Cogbill, C.V. 1994. Upland old-growth 

forests of Adirondack Park, New York, USA. Natural

Areas Journal. 14: 241-257.

Ziegler, S.S. 2000. A comparison of structural characteristics between old-growth and post-fire second-growth

hemlock-hardwood in Adirondack Park, New York,

U.S.A. Global Ecology and Biogeography. 9: 373-389.

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1 Research Forester and 2 Emeritus Scientist, USDA Forest Service, Pacific Northwest Research Station, 3625 93rd Avenue SW, Olympia, WA 98512, USA:

Email for corresponding author: dmarshall@fs.fed.us

Balancing Ecosystem Values Proceedings, Regional Experiments

Evaluation of Silvicultural Options for Harvesting 

Douglas-fir Young-Growth Production Forests

David D. Marshall1 and Robert O. Curtis2

INTRODUCTION

The great productivity of the maritime forests of the

Pacific Northwest has long been recognized. Beginning in

the mid-1800s, its large inventory of untouched timber

provided the basis for establishment and development of a

large timber industry that was a major contributor to development of the region. Until quite recently timber production

was the major objective on most federal and private land in

the region. Fire protection, roads, improved harvesting systems, improved regeneration systems, and strong markets

all favored more intensive silviculture. Investments in managing stands and increased growth rates pushed rotation

ages down. By the 1980s, many landscapes in the region

were dominated by clearcuts and young plantations. The

result was that timber production was often seen in direct

conflict with other forest values (habitat, visuals and watersheds). 

With the increase in public concern and involvement,

many public forestland managers are looking for alternatives

to the traditional and visually objectionable clearcut. While

ABSTRACT

This report summarizes data from establishment of the Blue Ridge and Copper Ridge installations and 5-year growth

information from Blue Ridge, which are part of the Silvicultural Options for Young-Growth Douglas-fir Forests study on

the Capitol State Forest near Olympia, Washington. Six silvicultural regimes are compared: clearcut, two-age, patch cut,

group selection, continued thinning on an extended rotation, and untreated control. The study aims to create widely different

stand conditions and to evaluate them from the standpoints of timber production, costs, visual effects, and public acceptance.

It is a cooperative effort of the Pacific Northwest Research Station of the USDA Forest Service, Washington Department of

Natural Resources, University of Washington, University of Idaho and Oregon State University.

KEYWORDS: Silvicultural systems, multiple use, visual effects, landscape management, Pseudotsuga menziesii.

119

the region has gained great experience with even-aged

silvicultural systems since the 1940s, there has been very

little investigation of alternatives (Curtis 1998). Although

much existing knowledge can provide guidance in developing possible management strategies for multiple objectives

(Curtis et al. 1998), there have been only limited (and often

poorly designed) tests of alternatives to traditional clearcutting, and managers have little experience with potential

alternatives.

As a result of public concerns, forest managers of the

Washington State Department of Natural Resources (DNR)

began trying harvesting alternatives to clearcutting in the

early 1990s. They soon recognized the need for quantitative

evaluation of results of possible alternatives to guide their

management decisions. They turned to the scientists of the

Silviculture and Forest Models team of the USDA Forest

Service’s Pacific Northwest Research Station (PNW).

Together, the land managers of the DNR and scientists of

the PNW developed and implemented the Silvicultural

Options for Young-Growth Douglas-fir (Pseudotsuga 

menziesii (Mirb.) Franco) Forests study.
METHODS

Study Objectives

The Silvicultural Options for Young-Growth Douglas-fir

Forests study is intended to provide comparisons of silvicultural regimes that will have long-term value for research

and demonstration. The regimes included were selected to

represent a continuum of forest cover (removed and retained)

and disturbance (intensity and frequency). Each regime was

considered biologically and operationally feasible and one

that could be implemented as part of a managed, sustainable

forest landscape to provide different levels and mix of

financial returns, wood production and nontimber values. 

Specific objectives are to

• Create on-the-ground examples of contrasting silvicultural regimes that can be evaluated for effectiveness 

in reducing visual and other environmental impacts of

forestry operations while providing high timber outputs

over time.

• Monitor development of stands under these regimes over

time in a manner that provides quantitative estimates of

change, outputs, and costs and allows statistically valid

tests of differences between regimes.

Specific studies that have been implemented to date

include monitoring residual tree growth, damage and mortality; stand development and yields; costs of harvesting

and stand tending; harvesting production; soil disturbance

impacts; visual quality and public response; and song bird

populations. The wide range of studies has required a cooperative approach that includes scientists from the Pacific

Northwest Research Station, Washington State Department

of Natural Resources, University of Washington, University

of Idaho and Oregon State University.

Study Design

The study is a randomized block experiment with six

treatments and three replications. The treatments are assigned

randomly and applied to units of 10 to 30 ha each. Curtis et

al. (1998) present the rationale for the treatments selected.

The six treatments applied are

1. Clearcut – a conventional even-aged system that has

been widely applied in the Douglas-fir region of Oregon,

Washington, and British Columbia that removes nearly

100 percent of trees and is regenerated by replanting. It

is included to provide direct quantitative comparisons of

costs and outputs with the other treatment regimes.

2. Two-Age – a two-aged system that retains about 40

evenly spaced, vigorous trees per ha in the overstory and

establishes a second age-class of trees in the understory

by planting. Initially this treatment resembles a shelterwood treatment; however, the overstory trees will be 

carried through the second rotation to provide partial

forest cover and future large, high-quality trees.

3. Patch Cut – an uneven-aged mosaic of even-aged patches

created by periodically (15-year cycle) harvesting 20

percent of the area in small patch cuts ranging in size

from 0.6 to 2.0 hectares (ha). Patches are planted and the

areas surrounding the patches are thinned as needed to

maintain vigorous growth. This treatment avoids large

harvest areas like the clearcut, but allows for individual

patches to be treated with well-developed, even-aged

methods. The lower limit of patch size was adopted to

provide an adequate light regime for Douglas-fir and

minimize future damage to the surrounding stand from

harvesting. Over time the area will be converted to an

uneven-aged mosaic of even-aged patches. 

4. Group Selection – an uneven-aged system in which 20

percent of the area is harvested at 15-year intervals in

small groups of trees that create openings from approximately 0.02 ha up to 0.6 ha and distributed randomly

throughout the stand. Openings greater than 0.04 ha 

are planted and the areas surrounding the groups are

thinned as needed to maintain vigorous growth. This

regime resembles the patch cut treatment, but with the

opening sizes not exceeding 0.6 ha. This was chosen

because it may reduce visual impacts, yet it is expected

to have higher harvest and management costs and may

favor more light tolerant species over Douglas-fir.

5. Extended Rotation with Commercial Thinning – a

typical thinning from below that targets removal of

about one fourth of the basal area throughout the stand.

Unlike the first four treatments that initiate Douglas-fir

regeneration, thinning defers the regeneration harvest

and takes advantage of the ability of thinned Douglasfir to maintain high growth rates while producing

some revenue and reducing the land area in the visually

obtrusive regeneration stage of stand development.

Regeneration of the next generation of trees in this

regime could eventually be done by any one of the

above methods.

6. Extended Rotation without Thinning (Control) – this

treatment also defers a regeneration harvest, but unlike

the commercial thinning treatment, no trees are removed.

120
This is another option, like thinning, for adjusting

unbalanced age distributions by carrying stands to

longer ages and for reducing visual impacts of regeneration harvesting on the landscape. 

All of the study sites are located on the Capitol State

Forest, southwest of Olympia in western Washington (lat

46.85° N, long 123.15° W). The Washington State DNR

manages this forest and applied treatments as part of their

operational timber sales program which meets all forest

practices requirements. The three replications are Blue Ridge

(harvested in 1998), Copper Ridge (harvested in 2002) and

Rusty Ridge (harvested in 2004). Figure 1 shows the Copper

Ridge site after the initial harvest. All the units represent

productive site of mostly Douglas-fir sites but differ in age

and harvesting requirements (table 1). The Blue Ridge and

Copper Ridge sites are older and originated after harvesting

and fire whereas the Rusty Ridge site is younger and originated from planting after harvest. The range in stand characteristics created in this experiment will provide operational

experience for managers implementing these regimes in a

range of conditions and using different harvesting methods.

For assessment of tree growth and stand development, 

a grid of permanent sample plots has been established in

each treatment unit. The number of plots in a treatment

ranges from 15 to 38 depending on the expected variability.

Each sample plot consists of 3 nested fixed area subplots: 

a 0.08 ha plot for trees greater than 24.4 cm diameter at

breast height (d.bh., measured 1.37 m above the ground), 

a 0.04 ha plot for trees greater than 14.0 cm and up to 24.4

cm d.bh., and a 0.01 ha plot for trees from 4.0 cm up to

14.0 cm d.b.h. Regeneration (trees less than 4 cm d.b.h.)

and low-ground vegetation are assessed on four satellite

plots (nested 0.002 ha and 0.01 ha sized plots respectively)

each centered at 16.1 m in cardinal directions from the main

plot center. All trees in the plots are identified by species

and measured for d.b.h. with heights and height-to-crownbase sampled. Low-ground vegetation is characterized by

height and cover for species groups. Studies by Bradley et

al. (2004), Reutebuch et al. (2004) and Wilson (2004) are

also referenced to this plot grid.

RECENT FINDINGS

Curtis et al. (2004) have reported results from the establishment of the first installation (Blue Ridge) in 1998. Since

1998, the two other installations have been, or are in the

process of being harvested, and the Blue Ridge site has had

a 5-year remeasurement. Although certain questions can

121

Figure 1—Aerial photo after 2002 harvest of the Copper Ridge site showing locations of treatment regimes (photo area is about 4 km wide).

Table 1—Summary of three installations of the Silvicultural Options for Young-Growth 

Douglas-fir Forests study

Harvest Harvesting Total area Stand Stand age Site indexa

Installation year system (ha) origin (years) (meters)

Blue Ridge 1998 Ground 105 Natural 70 39

Copper Ridge 2002 Cable 109 Natural 69 30-39

Rusty Ridgeb 2004 Ground 89 Planted 49 37

a Site index is at age 50 (breast height).

b Rusty Ridge age and site index is based on preharvest stand exam data. 
only be answered over the long term as the stands develop,

important information has already been obtained through

the efforts of establishing these studies. Briefly presented

below are some of these results, updated to include the 

second study site (Copper Ridge).

The Blue Ridge and Copper Ridge units represent similar stand ages, but differ in three important respects. First,

loggers under contract by the DNR harvested the Blue

Ridge unit, and specific log sorts were sold to different

buyers. At Copper Ridge, the unit was sold on a lump sum

bid basis to a buyer who arranged for logging; this is the

usual timber sale process for the DNR. The second difference was that Blue Ridge was harvested by using ground

based skidding whereas the steeper terrain of Copper Ridge

required a cable harvesting system. Third, although the sale

areas were of similar age and area, the total volume removed

at Copper Ridge was only about 55 percent of Blue Ridge,

reflecting a lower site, smaller trees, more root rot, damage

from a 1996 ice storm, and recent thinning sales within in

the Copper Ridge area.

Sale Layout Costs

Each replication represented an operational timber sale

that required all of the typical activities carried out by DNR

foresters including, marking and surveying boundaries,

marking cut or leave trees, and the administrative paper

work. Once harvesting had begun, operations were monitored for compliance with forest practices rules, contracts

and the study design. Figure 2 compares the layout and

monitoring costs for the Blue Ridge and Copper Ridge

units. The layout times were slightly greater for Copper Ridge

compared to Blue Ridge (0.06 compared to 0.04 hours per

1000 board feet) and may reflect the lower removal volume

and steeper terrain at Copper Ridge. Marking involved either

designating trees for retention (two-age) or harvest (patches,

group and thinning). With the exception of the two-age

treatment, marking times were less at Copper Ridge, possibly reflecting experience gained at Blue Ridge and the lower

volumes. The greater marking times in the two-age treatment

at Copper Ridge may reflect the steep terrain. Although the

compliance monitoring costs are not well related to the

treatment unit, the Copper Ridge unit had slightly greater

total times (0.08 compared to 0.06 hours per 1000 board

feet).

Harvesting Costs 

Stump-to-roadside harvesting costs were collected by

Coulter (1999) and Hartley (2003) at Blue Ridge and Copper

Ridge respectively. These costs, normalized for piece size

and yarding distances, are shown in figure 3 (costs for harvesting the thinning treatment were not collected at Copper

Ridge). As expected, costs were lowest for the clearcut

units, and the costs were greater (about 1.5 times) for the

cable system used at Copper Ridge. For both sites, the costs

of harvesting the two-age, patch cut and group selection

units were about 1.2 times greater than the clearcut. In

addition to harvesting production and costs, soil disturbance, as a result of harvesting, has been measured at Blue

Ridge and Copper Ridge. Cable-based harvesting resulted

in about 8 percent more area in an undisturbed state compared to ground-based harvesting (Klepac and Reutebuch

2003).

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Figure 2—Sale layout and marking costs in hours per thousand board feet (Scribner), by treatment regime (CC =

clearcut, 2A = two-age, PT = patch cut, GP = group selection and TH = thinning) and activity for Blue Ridge and

Copper Ridge.
Timber Production 

This is a long-term experiment, and data are being collected to quantify stand growth, regeneration, changes in

stand structure and species composition, and the required

treatment costs. Data from the first remeasurement at Blue

Ridge suggest that the 5-year post-harvest stand volume

growth is related to the growing stock (volume) retained

after harvest and that thinning appeared to be beneficial in

maintaining and enhancing growth of the residual stand

(fig. 4). After accounting for mortality (gross growth), the

volume growth percent (volume growth as a percent of the

initial volume) was similar between the treatments. Periodic

volume growth for the control treatment may have been

somewhat reduced compared to the other treatments because

it has a higher proportion of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata

Donn.). In addition, the control treatment was more noticeably impacted by mortality from root rot and wind throw

had the greatest impact on the patch cut (see Curtis et al.

2004). Data from several more measurement cycles on all

three replications will be required to determine whether

significant differences in post-harvest growth exist between

treatments.

123

Figure 3—Normalized harvest costs in dollars per thousand board feet (Scribner), by treatment regime (CC =

clearcut, 2A = two-age, PT = patch cut, GP = group selection and TH = thinning) for Blue Ridge and Copper

Ridge (data for the thinning treatment was not available at Copper Ridge).

Figure 4—Relative 5-year merchantable cubic volume per hectare periodic annual increment (PAI) and percentage of

growth by the post-harvest volume and treatment regime for Blue Ridge (1998-2004) as compared to the unharvested

control. Gross volume estimates contain periodic mortality and estimated losses to wind throw (CC = clear-cut, 2A =

two-age, PT = patch cut, GP = group selection, TH = thinning, and CN = control).
Other Values 

There are many possible nontimber values that could 

be studied. With the resources available to date, efforts have

focused on two—public reaction to visual impacts and bird

use. Bradley et al. (2004) have summarized the results of

surveys to assess foreground views at Blue Ridge after treatment. They found that people tended not to discriminate

among treatment types but rather by the overall patterns 

of openings, tree size variation and the amount of green

foliage. Later surveys are assessing changes in viewer 

perceptions with time since harvesting and differences in

background scenes created by the range of treatments. Spring

bird surveys were done after harvest at Blue Ridge (Wilson

et al. 2004) and Copper Ridge by using fixed radius point

counts and similar procedures (although Copper Ridge was

less intensively sampled with fewer visits and points and

did not include the thinning treatment due to cost). In both

surveys, the clearcut had the fewest species detected and

the lowest relative abundance (number of birds detected per

visit per point), although in both cases there were some

species only detected in the clearcut (table 2). For Blue

Ridge, the relative abundance generally increased with tree

cover whereas at Copper Ridge, all of the treatments other

than the clearcut were similar. Total number of species

detected was greatest in the patch cut units and control at

Blue Ridge and in the patch cut and group selection units

at Copper Ridge (the thinning treatment was not surveyed).

CONCLUSIONS

The Silvicultural Options for Young-Growth Douglasfir Forests study was initiated in response to the need for

quantitative data on the stand-level responses to alternative

silvicultural systems applied to Douglas-fir. Its large-scale,

long-term, operational orientation and integrated approach

will allow scientists and managers to gain valuable experience in implementing new treatments and generate data to

make more informed choices in applying silvicultural treatments.

Key to the success of a project of this scale is the cooperation between the research organization, the landowner,

and the operational foresters who are responsible for implementing the treatments. The partnership between PNW

scientists, DNR managers and university scientists has

provided joint ownership of this project and relevance to

the DNR’s management objectives.

This study has already generated interest throughout the

region. The PNW and DNR have hosted numerous tours of

foresters and other interested parties. The British Columbia

Ministry of Forests also installed a study based on the

same design on Vancouver Island in 2001 and is currently

installing another as part of their Silviculture Treatments for

Ecosystem Management in the Sayward (STEMS) study

(described in this volume, e.g., deMontigny).

124

Table 2—Bird abundance (mean number of birds detected per point per day), richness (mean 

number of species detected per point per day) and total species detected, by treatment regime 

for Blue Ridge and Copper Ridge

Relative abundance Species richness (mean Total species

(mean birds/point/visit) species/point/visit) detected

Blue Copper Blue Copper Blue Copper

Treatment Ridge Ridge Ridge Ridge Ridge Ridge

Clearcut 1.37 1.67 0.72 0.67 13 6

Two-age 1.87 4.67 0.66 1.33 15 16

Patch cut 1.81 4.73 0.62 1.33 23 19

Group selection 2.23 4.27 0.93 1.27 18 19

Thinning 2.68 na 0.99 na 26 na

Control 2.97 4.56 1.20 0.90 17 10

Na = not surveyed
REFERENCES

Bradley, G.A.; Kearney, A.R.; Wager, J.A. 2004. Public 

relations research. In: Curtis, R.O.; Marshall, D.D.;

DeBell, D.S., eds. Silvicultural options for young-growth

Douglas-fir forests: the Capitol Forest study – establishment and first results. Gen. Tech. Rep. PNW-GTR-598.

Portland, OR. U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station: 63-73.

Chapter 7.

Coulter, K.M. 1999. The effects of silvicultural treatments 

on harvesting production and costs. Moscow, ID:

University of Idaho. 113 p. M.S. thesis.

Curtis, R.O. 1998. “Selective cutting” in Douglas-fir. 

Journal of Forestry. 96(7): 40-46.

Curtis, R.O.; DeBell, D.S.; Harrington, C.A.; Lavender, 

D.P.; St. Clair, J.B.; Tappeiner, T.C.; Walstad, J.D. 1998.

Silviculture for multiple objectives in the Douglas-fir

region. Gen. Tech. Rep. PNW-GTR-435. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 123 p.

Curtis, R.O.; Marshall, D.D.; DeBell, D.S., (eds). 2004. 

Silvicultural options for young-growth Douglas-fir

forests: the Capitol Forest study—establishment and

first results. Gen. Tech. Rep. PNW-GTR-598. Portland,

OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 110 p.

Hartley, D.S. 2003. A case study on the effects of four 

silvicultural prescriptions on cable harvesting productivity and cost in western Washington. Moscow, ID:

University of Idaho. 42 p. M.S. thesis.

Klepac, J.; Reutebuch, S.E. 2003. Preliminary soil disturbance assessment of a skyline logging operation performing five silvicultural prescriptions. Paper No. 03-

5014. Annual International Meeting. Las Vegas, NV:

American Society of Agricultural Engineers (ASAE): 

1-12.

Reutebuch, S.E.; Andersen, H.E.; Ahmed, K; Curtis, T.A. 

2004. Evaluation of laser light detection and ranging

measurements in a forested area. In: Curtis, R.O.;

Marshall, D.D.; DeBell, D.S., eds. Silvicultural options

for young-growth Douglas-fir forests: the Capitol Forest

study – establishment and first results. Gen. Tech. Rep.

PNW-GTR-598. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research

Station: 94-97. Chapter 10.

Wilson, T.M.; Carey, A.B.; Haveri, B.A. 2004. Spring bird 

survey and social perceptions. In: Curtis, R.O.; Marshall,

D.D.; DeBell, D.S., eds. Silvicultural options for younggrowth Douglas-fir forests: the Capitol Forest study –

establishment and first results. Gen. Tech. Rep. PNWGTR-598. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station: 

80-93. Chapter 9.

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1 Research Ecologist and 2 Research Forest Pathologist, USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 2770

Sherwood Lane, Suite 2A, Juneau, AK 99801, USA. Email for corresponding author: mmcclellan@fs.fed.us

Balancing Ecosystem Values Proceedings, Regional Experiments

Maintaining Old-Growth Features in Forests Used 

for Wood Production in Southeast Alaska

Michael H. McClellan1 and Paul E. Hennon2

INTRODUCTION

The coastal rainforest of Alaska begins in southern

southeast Alaska, extends through Prince William Sound

and the Kenai Peninsula, and reaches its limit at Kodiak

Island. Temperate conditions and infrequent large-scale

disturbance have produced extensive tracts of old-growth

forest—roughly 80 percent of the productive forest in

southeast Alaska is considered old growth. Western hemlock (Tsuga heterophylla (Raf.) Sarg.) dominates these

forests (83 percent by number of trees per unit area) and

common associates are Sitka spruce (Picea sitchensis

(Bong.) Carr.), western redcedar (Thuja plicata Donn), 

yellow-cedar (Chamaecyparis nootkatensis (D. Don)

Spach), and mountain hemlock (Tsuga mertensiana (Bong.)

Carr.). Most of the forest land in this region resides in the

ABSTRACT

Clearcutting and even-aged management dominated the management of wood-producing forest land in southeast Alaska

from the 1950s through the 1990s. Although well suited for wood production, from 1970 to the 1990s, this system came

under increasing criticism for its effects on other forest values. To provide a range of scientifically tested silvicultural options,

the USDA Forest Service Alaska Region and Pacific Northwest Research Station created a collaborative study of alternatives

to clearcutting. The research included retrospective studies to provide early results and interim guidelines to managers and a

long-term experimental study to provide greater scientific credibility and wider scope of inference. The experimental study

has three blocks with nine operational-scale treatments each. The treatments include both even-age and uneven-age silvicultural systems and vary three factors: cutting intensity, spatial arrangement of retained trees, and patch size. Retrospective

study results suggested that partial cutting can maintain diverse and abundant understory plant communities without reductions in stand value owing to species conversions, declining productivity, or increased levels of tree damage. Early results

from the experimental study demonstrated the importance of the spatial pattern of retained trees. Tree injuries and mortality

increased in treatments that included uniform individual-tree selection. Gap and aggregate treatments were far more effective

at protecting retained live trees and snags.

KEYWORDS: Silviculture, variable-retention harvesting, alternatives to clearcutting, old-growth forest, southeast Alaska.

127

Nation’s two largest national forests: the 7.0 million-ha

Tongass and the 2.8 million-ha Chugach.

Most of the large-scale timber harvesting in this region

was in the productive old-growth forests of southeast

Alaska, on the Tongass. Post-war efforts to diversify the

economy and provide year-round jobs led in 1954 to the

construction of a pulp mill in Ketchikan and, later, a second

pulp mill in Sitka. Fifty-year contracts were established to

provide national forest timber to these mills and the conversion of uneven-aged old-growth forests to even-aged

stands began in earnest (Rakestraw 1981). The dominant

silvicultural system from the mid-1950s to the mid- 1990s

was a regeneration harvest with clearcutting, followed by

natural regeneration without site preparation. On productive sites, managers prescribed precommercial thinning at
15 to 25 years and commercial thinning at 70 to 80 years.

At the end of the 90- to 120-year rotation, the stands were

to be clearcut again. By 2001, 267 400 ha in southeast

Alaska had been harvested: 175 400 ha on the Tongass, 79

600 ha on Alaska Native corporation lands, and 12 400 ha

on State of Alaska and other lands (Barbour et al., in press).

This system efficiently produced wood, but after 1970 

it came under increasing criticism for its effects on other

forest values: reduced visual quality and associated effects

on tourism, degradation of fish and wildlife habitat, reduced

slope stability, and simplification of forest structure and

associated losses of ecological functions and biological

diversity. Uneven-aged management and variable-retention

harvest systems were obvious alternatives to the status quo,

but managers resisted adopting these methods, citing the

potential for (1) increased logging costs; (2) increased

damage to residual stands from hemlock dwarf mistletoe,

windthrow, tree injuries and subsequent wood decay; (3)

reduced growth of young trees due to shading by residual

trees; and (4) favoring the more shade-tolerant (and less

valuable) western hemlock over Sitka spruce. 

The adoption of ecosystem management by the Forest

Service in the early 1990s increased pressure to consider

alternatives to clearcutting, but there was little information

from practical experience or scientific study to guide management. Assessing the tradeoffs between maintaining the

status quo and adopting silvicultural alternatives was

impossible without further information, so the Alaska

Region and Pacific Northwest Research Station created a

collaborative study of alternatives to clearcutting.

STUDY DEVELOPMENT

AND IMPLEMENTATION

Much of the debate over old-growth management centers

on this question: Can the ecological functions of oldgrowth be maintained without resorting to a “hands-off”

approach, or is active management incompatible with oldgrowth functions and values? More specifically, can oldgrowth forests used for wood production provide key

old-growth features and functions required by important

species? The study Alternatives to Clearcutting in the OldGrowth Forests of Southeast Alaska (ATC) (McClellan et al.

2000) was developed to begin to address these broad questions. From the onset, the ATC study involved close collaboration between Forest Service research and management

in establishing research objectives, identifying potential

sites, designing treatments, and preparing silvicultural prescriptions and marking guides. Tongass National Forest

personnel took the lead in preparing the environmental

analyses, and preparing and administrating timber sales.

Researchers took the lead in collecting, analyzing, and

reporting data. 

To maintain support for the ATC study, we planned to

provide both short-term and long-term results. We would

use retrospective studies to provide early results and interim

guidelines to managers and concurrently establish an experimental study to provide greater scientific credibility and

scope of inference. Research and management jointly established research objectives for the studies and selected the

main biological, physical, and socioeconomic responses to

study. Biological responses included stand dynamics, understory diversity and abundance, tree damage agent dynamics,

bird diversity and abundance, headwater stream productivity,

and deer habitat quality. Physical responses included slope

stability, groundwater response, and sediment production

and transport. Socioeconomic responses included logging

feasibility, implementation issues, the costs of planning,

implementation, and monitoring, aesthetic qualities, and

social acceptability.

Retrospective study fieldwork was completed during

1995 and 1996, when 18 partially cut stands ranging in age

from 12 to 96 years were intensively examined. All the

stands were at low elevations (< 100 m) and within 2 km

of saltwater. The “treatments” were harvest intensity and

time since harvest. A subset of the responses listed above

were assessed: stand dynamics (growth, regeneration, and

mortality) (Deal and Tappeiner 2002), understory abundance

and diversity (Deal 2001), tree damage agents (Hennon et

al. 2002), and bird diversity, abundance, and reproductive

success (De Santo et al. 2003).

Planning of the experimental study began in 1994. Two

hypotheses or assumptions guided the treatment design of

the experimental study:

1. Forest organisms are well-adapted to natural patterns of

disturbance and to the stand structural characteristics

created following disturbance.

2. Silvicultural systems that retain key old-growth structural

features in sufficient quantity will preserve functions and

values associated with old-growth.

What are the “key old-growth structural features” in southeast Alaska? According to a regional working group (Capp

et al. 1992), they include large, old, decadent trees, multiple canopy layers, standing snags, down woody debris, and

a diverse and abundant herb layer. The treatments were

meant to maintain old-growth structure and function, not

restore it. Three factors were included in the treatments:

128
(1) cutting intensity (0 to 100 percentage of basal area

retained), (2) spatial arrangement of retained trees (in clumps,

gaps, or uniformly distributed), and (3) patch size (32-, 64-,

or 96-m diameter clumps or gaps).

The study planners insisted on several important conditions for the experiment: treatments must be assigned

through a random process, experimental units must be large

enough to encompass much of the natural heterogeneity of

the stands and to minimize edge effects, and the study must

be replicated widely throughout southeast Alaska. The implementation of the study was at the mercy of wood markets

and activist litigation. Recognizing this, many of the cooperating scientists collected extensive pretreatment information that would not only document baseline conditions, but

also add to our understanding of unmanaged old-growth

forests. Thus, some scientific value could be derived in 

the event the treatments were not completed.

Nine treatments (fig. 1) were randomly assigned to 18-ha

(minimum area) experimental units, replicated in three

blocks. Detailed descriptions of the treatments, silvicultural

systems and prescriptions, and site characteristics are presented by McClellan et al. (2000) and McClellan (2004). A

detailed, reconciled study plan was published to document

the study’s objectives and methods for future researchers

(McClellan et al. 2000).

The experimental treatments were designed to ensure

that key old-growth features remained following timber

harvesting, but designating live trees and snags for retention does not guarantee they will survive logging operations or subsequent exposure to natural damaging agents

such as wind, ice, pests, and pathogens. Live leave trees

may be damaged or killed during logging when they are

struck by cut trees. Snags are subject to this as well and, in

addition, snags are frequently felled to comply with worker

safety rules. To determine the ability of each treatment to

maintain these structural features, we assessed the fate and

condition of retained live trees and large, relatively sound

snags (d.b.h. 25 cm or greater and decay class of 1 or 2)

immediately following logging and 5 years later.

Examining the timeline of the ATC experimental study

might prove instructive to researchers considering undertaking a similar study:

• 1993: U.S. Forest Service Ecosystem Management

Research Initiative announced

• 1994: Funding obtained, study planning, first block selected

• 1995: Block 1 (Hanus Bay) established, retrospective 

study fieldwork began

• 1996: Block 2 (Portage Bay) established, retrospective 

study fieldwork completed, timber sale for Block 1 in 

litigation

• 1997: Block 3 (Lancaster Cove) established, Block 1 

harvested

• 1999: Block 2 (Portage Bay) harvested

• 2002: Fifth-year remeasurement of Block 1, timber sale 

for Block 3 mired in bankruptcy proceedings

• 2003: All nonvegetation studies terminated

• 2004: Fifth-year remeasurement of Block 2, timber sale 

for Block 3 reactivated

• 2005: Block 3 harvested.

This illustrates some of the risks of operational-scale, longterm studies. Forces outside the control of researchers can

129

Figure 1—Schematic representation of treatments that are alternatives to

clearcuts.
have a profound impact on the conduct of research and may

greatly complicate data analysis and reporting of results.

Further, the commitment of institutions and cooperating

researchers may wane as personnel, funding, and priorities

change.

SELECTED RESULTS

The retrospective study achieved the objective of providing early results and interim guidance for managers. 

The scope of inference for the results is somewhat limited

because most of the study sites were in beach-fringe stands,

but the results were useful nonetheless. There were three

major findings:

1. Partial cutting had no significant effect on tree species

composition, and the researchers concluded that concerns regarding shifting species composition, reduced

Sitka spruce regeneration, and reduced stand growth

were unsubstantiated (Deal and Tappeiner 2002).

2. Partial cutting did not result in significant changes in the

amount of windthrow, hemlock dwarf mistletoe infection, bole wounding, or tree mortality (Deal et al. 2002).

3. Overall, the partially cut and uncut areas had similar

plant community structures (species composition and

abundance) and species richness, but plant community

structure differed significantly where >50 percent of the

basal area had been removed (Deal 2001). Deal (2001)

suggested that similarities between old-growth stand

structure and the heterogeneous stand structures of partially cut stands could account for the observed similarities in understory plant communities.

These results were reported in the traditional scientific literature, but the researchers used several other methods to

ensure the information got to managers quickly, including

annual progress reports, briefings at regional resourcespecialist meetings, and field tours.

Early results from the experimental study have included

insights gained from pretreatment measurements in the 27

unmanaged old-growth stands, coupled with early post-treatment response data. These include findings on disturbance

dynamics and old-growth forest structure (Hennon and

McClellan 1999, 2003), social acceptability of alternatives

to clearcutting (Burchfield et al. 2003, Clausen and Schroeder

2004), avian ecology (De Santo and Willson 2001, De Santo

et al. 2003), groundwater response (Johnson et al., n.d.),

and headwater stream trophic relationships (Musslewhite

and Wipfli 2004; Wipfli and Gregovich 2002; Wipfli, in

press). As with the retrospective study, researchers have

used briefings, field visits, and internal reports to convey

their findings to managers, in addition to scientific publications. The experimental sites are particularly important as

demonstration sites, and there have been many visits by

researchers, managers, news media, and policy makers.

Snag survival immediately following logging (table 1)

demonstrated that treatments where 25 percent or less of the

basal area was retained generally did not preserve enough

snags to meet the requirements of the Alaska Region oldgrowth definitions (Capp et al. 1992). As expected, retaining trees and snags in clumps generally protected a higher

percentage of snags for a given level of basal-area retention.

At each site, only three of seven noncontrol treatments 

protected sufficient numbers of snags. The results from the

Portage Bay unit with 75-percent retention and individualtree selection are interesting: even though 75 percent of the

existing snags were retained, there were too few to meet the

minimum requirements of the old-growth definition. This

suggests that in old-growth stands with fewer snags than

normal, extra effort may be necessary to retain the desired

number of residual snags.

The rates of top, bole, and root wounding in live trees

after logging also demonstrated the importance of the spatial

distribution of retained trees. Overall, 18 percent of the

retained trees at Hanus Bay (n = 1639) sustained some form

of injury and at Portage Bay 29 percent of the trees (n =

2950) were injured. Injury rates varied widely by treatment

(fig. 2): treatments including individual-tree selection promoted high injury rates to leave trees in contrast to treatments where cutting was concentrated in clumps (gaps)

and injury rates were much lower.

Analysis is ongoing of fifth-year response data from the

first two blocks. We expect that this will soon provide useful findings on leave-tree growth and mortality, incidence

of windthrow and other damaging agents, conifer regeneration, understory diversity and abundance, and deer-forage

availability.

RELEVANCE AND IMPACT

Researchers are engaged in a lively debate over the role

of large-scale, long-term studies in providing the basis for

science-based resource management. The studies consume

significant resources, and there is the ever-present risk that

they will become irrelevant as societal demands and expectations evolve over the life of the study. The ATC study is

now 10 years old, and the third block has not been harvested;

it is worth asking whether the study remains useful and

relevant. Despite great controversy, old-growth harvesting

130
continues on national forest, state, and Alaska Native corporation lands in southeast Alaska. For the most part,

young-growth stands in this region are still too young to be

harvested economically. Some opportunities exist for commercial thinning of young-growth, but the timber industry

in southeast Alaska is largely dependent on old-growth 

harvesting and will continue to be for the next decade or

longer. Much of this harvesting will employ variable-retention, so it is necessary to continue research to quantify the

tradeoffs associated with its use. Managers of the Tongass

National Forest view the ATC study as a continuing source

of scientific information to guide management and as an

essential monitoring tool to determine the effects of clearcutting alternatives. In addition, the costs and benefits of

variable-retention harvesting in old-growth forests continue

to be debated among resource managers, the timber industry,

and interested citizens—raising issues that cannot be resolved

in the absence of credible scientific information.

Finally, we must ask if the ATC study has affected management, at least on national forest land. There have been

dramatic changes in timber-harvesting practices since the

onset of the study in 1994. In that year, 3683 ha were harvested, all by clearcutting. The revised Tongass land management record of decision (USDA FS 1997: 5) estimated

that 80 percent of the planned regeneration harvesting

would be clearcutting with subsequent even-aged management. At least 20 percent would be variable-retention harvesting with two-aged management. The record of decision

131

Table 1—Post-harvest survival of class 1 and 2 snags with d.b.h. 25 cm or greater. Bold text indicates that after treatment the stand included enough snags to meet the criteria of the Alaska Region old-growth definition for this forest

type (Capp et al. 1992).

Treatment numbera

1 2 8 3 6 94 7 5

Treatment description

Clearcut Wildlife Tree ITSb/Gaps ITS Clump Gaps ITS ITS/Clump Control

Percentage of basal-area retention

Site 0 5 25 25 25 75 75 75 100

Hanus Bay 8.8 0.0 18.8 16.7 64.3 72.4 90.5 83.3 100

Portage Bay 4.4 10.7 5.9 13.3 47.8 52.9 75.0 100.0 100

a Treatment number from figure 1

b ITS = uniform individual-tree selection From McClellan (2004).

Figure 2—The percentage of residual trees wounded during logging, by

treatment.
further predicted that about 80 percent of the allowable

harvest would employ conventional logging systems and

the remaining 20 percent would come from lands that were

isolated or that required special yarding equipment, such as

helicopters (USDA FS 1997: 8). By 2002, however, a review

of silvicultural prescriptions in Tongass National Forest

project-planning documents revealed that 29 percent prescribed even-aged management, 33 percent prescribed twoaged management, and 38 percent prescribed uneven-aged

management. The prescribed logging systems were 37 percent conventional and 63 percent helicopter.3 This rapid

shift in management practices cannot be attributed solely 

to the impact of the ATC study, but discussions with managers reveal it clearly played a role. The findings of the 

retrospective study and the early results from the experimental study allayed some of the concerns over variableretention harvesting. The experimental study was conducted

at an operational scale and relied on standard timber sales

to implement the treatments, effectively demonstrating that

variable-retention harvesting was technically feasible and

viable in the existing timber marketplace. If the experiments

were smaller scale (as were many silvicultural field trials in

the past) or implemented with service contracts, it is likely

the influence on managers would have been much less.

ACKNOWLEDGMENTS

This paper is a contribution from the USDA Forest

Service study, Alternatives to Clearcutting in the Old-Growth

Forests of Southeast Alaska, a joint effort of the Pacific

Northwest Research Station, the Alaska Region, and the

Tongass National Forest. The authors wish to thank Toni

De Santo, Colleen Grundy, and Frances Biles for their helpful reviews and Jim Russell for sharing his knowledge of the

Tongass National Forest timber and silviculture programs.

REFERENCES

Barbour, R.J.; Zaborske, R.R.; McClellan, M.H.; Christian, 

L.E.; Golnick, D. [In press]. Young-stand management

options and their implications for wood quality and

other values. Landscape and Urban Planning.

Burchfield, J.A.; Miller, J.M.; Allen, S.; Schroeder, R.F.; 

Miller, T. 2003. Social implications of alternatives to

clearcutting on the Tongass National Forest: an

exploratory study of residents' responses to alternative

silvicultural treatments at Hanus Bay, Alaska. Gen.

Tech. Rep. PNW-GTR-575. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 28 p.

Capp, J.; Van Zee, B.; Alaback, P.; Boughton, J.; 

Copenhagen, M.; Martin, J. 1992. Ecological definitions

for old-growth forest types in southeast Alaska. Juneau,

AK: U.S. Department of Agriculture, Forest Service,

Alaska Region. 63 p.

Clausen, D.L.; Schroeder, R.F. 2004. Social acceptability 

of alternatives to clearcutting: discussion and literature

review with emphasis on southeast Alaska. Gen. Tech.

Rep. PNW-GTR-594. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research

Station. 37 p.

Deal, R.L. 2001. The effects of partial cutting on forest 

plant communities of western hemlock-Sitka spruce

stands in southeast Alaska. Canadian Journal of Forest

Research. 31: 2067-2079.

Deal, R.L.; Tappeiner, J.C. 2002. The effects of partial 

cutting on stand structure and growth of western hemlock-Sitka spruce stands in southeast Alaska. Forest

Ecology and Management. 159: 173-186.

Deal, R.L.; Tappeiner, J.C.; Hennon, P.E. 2002. Developing 

silvicultural systems based on partial cutting in western

hemlock-Sitka spruce stands of southeast Alaska.

Forestry. 75: 425-431.

De Santo, T.L.; Willson, M.F. 2001. Predator abundance 

and predation of artificial nests in natural and anthropogenic coniferous forest edges in southeast Alaska.

Journal of Field Ornithology. 72: 136-149.

De Santo, T.L.; Willson, M.F.; Bartecchi, K.M.; Weinstein, 

J. 2003. Variation in nest sites, nesting success, territory

size, and frequency of polygyny in winter wrens in

northern temperate coniferous forests. Wilson Bulletin.

115: 29-37.

132

3 Data on file at the Forestry Sciences Laboratory, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801, USA.
Hennon, P.E.; McClellan, M.H. 1999. Heart rot and other 

causes of small-scale disturbance in the temperate rain

forests of southeast Alaska. In: Trummer, L., comp.

Proceedings of the 46th Western International Forest

Disease Work Conference. Anchorage, AK: U.S.

Department of Agriculture, Forest Service: 97-105.

Hennon, P.E.; McClellan, M.H. 2003. Tree mortality and 

forest structure in the temperate rain forests of southeast

Alaska. Canadian Journal of Forest Research. 

33: 1621-1634.

Hennon, P.E.; McClellan, M.H.; Palkovic, P. 2002. Comparing deterioration and ecosystem function of decayresistant and decay-susceptible species of dead trees.

In: Shea, P., ed. Symposium on the ecology and management of dead wood in western forests. Gen. Tech.

Rep. PSW-GTR-181. Berkeley, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest

Research Station. 435-444.

Johnson, A.C.; Erhardt, R.; Edwards, R.T.; Woodsmith, R. 

[No date]. Groundwater response within areas of forest

harvest: implications to hillslope stability. On file with:

A.C. Johnson, Forestry Sciences Laboratory, 2770

Sherwood Lane, Suite 2A, Juneau, AK 99801, USA.

McClellan, M.H. 2004. Development of silvicultural 

systems for maintaining old-growth conditions in the

temperate rainforest of southeast Alaska. Forest Snow

and Landscape Research. 78: 173-190.

McClellan, M.H.; Swanston, D.N.; Hennon, P.E.; Deal, 

R.L.; De Santo, T.L.; Wipfli, M.S. 2000. Alternatives

to clearcutting in the old-growth forests of southeast

Alaska: study plan and establishment report. Gen. Tech.

Rep. PNW-GTR-494. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research

Station. 40 p.

Musslewhite, J.; Wipfli, M.S. 2004. Effects of alternatives 

to clearcutting on invertebrate and organic detritus

transport from headwaters in southeastern Alaska. 

Gen. Tech. Rep. PNW-GTR-602. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 28 p.

Rakestraw, L. 1981 (reprinted 1994). A history of the 

United States Forest Service in Alaska. R10 FR-03.

Juneau, AK: U.S. Department of Agriculture, Forest

Service, Alaska Region. 221 p.

USDA Forest Service. 1997. Record of decision: Tongass 

National Forest land and resource management plan

revision. Juneau, AK: U.S. Department of Agriculture,

Forest Service, Tongass National Forest. 44 p.

Wipfli, M.S. [In press]. Trophic linkages between headwater forests and downstream fish habitats: implications

for forest and fish management. Landscape and Urban

Planning.

Wipfli, M.S.; Gregovich, D.P. 2002. Export of invertebrates 

and detritus from fishless headwater streams in southeastern Alaska: implications for downstream salmonid

production. Freshwater Biology. 47: 957-969.

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1 Canadian Forest Service Pacific Forestry Centre, 506 West Burnside Road, Victoria, BC V8Z 1M5, Canada. Email for corresponding author:

amitchel@pfc.forestry.ca

2 Weyerhaeuser BC Coastal Timberlands, 65 Front Street, Nanaimo, BC V9R 5H9, Canada

Balancing Ecosystem Values Proceedings, Regional Experiments

Montane Alternative Silvicultural Systems (MASS): 

Designing Experiments for the Future

Alan K. Mitchell1 and William J. Beese2

Local and global demand to sustain multiple values from forest land has created pressure to diversify silvicultural systems.

In response, the Montane Alternative Silvicultural Systems (MASS) project was established in 1993 to test silvicultural alternatives to clearcutting that retain elements of preharvest forest structure. Objectives are to document the operational costs

and feasibility and to study the biological and silvicultural impacts. To date, there have been more than 20 integrated research

studies conducted at the site addressing feasibility and economics, soil disturbance and productivity, decomposition, leaching and nutrition, microclimate, ecophysiology of conifers, natural and planted regeneration, seedling response to competition and nutrition, vegetation succession and forest structure, growth and yield, forest bird and canopy insect diversity, forest

health, and the genetic consequences of alternative silvicultural systems. The project is a factorial design with three replicates of four silvicultural treatments: clearcut, patch cut, green-tree retention, and shelterwood. Although the MASS project

was established prior to the development and implementation of retention silvicultural systems in coastal British Columbia,

it provides a test bed for scientific experiments that address questions about the ecological impacts of aggregated and dispersed retention systems. Results from established studies and plans for future work aimed at moving toward science-based

forest management are discussed.

135
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1 Professor of Landscape Architecture and Director, Institute for a Sustainable Environment, University of Oregon, Eugene, OR 97403, USA. 

Email: rribe@uoregon.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Comparing Changes in Scenic Beauty Produced by 

Green-Tree Retention Harvests, Thinnings and Clearcuts: 

Evidence From Three Pacific Northwest Experiments

Robert G. Ribe1

INTRODUCTION

Visual aesthetics are often critical factors affecting 

forest management decisions. Increasing the beauty of

managed forests can enhance the social acceptability of

forest management (Ribe 2002) and is often required in

popular views, recreation areas, frequently seen places, and

other areas strongly valued by the public (USDA FS 1995).

Forest aesthetic choices often are evaluated through environmental impact statements. Aesthetic impacts must be

included in these, and the standard for all assessments is

change from baseline environmental conditions (Jain et al.

1993).

Many studies of aesthetic perceptions of forestry have

been conducted (Ribe 1989), but few have investigated

changes in the same forests or scenes due to forest treatments, as would best inform impact assessments. Instead,

studies typically compare different forests and sometimes

ABSTRACT

The same in-stand photographs were taken before and after six different green-tree retention harvests, including one in

old growth. More such photo replicate pairs were also taken in light and heavy thinnings of young stand and in clearcuts.

All the photos were rated for scenic beauty by samples of the public. Short-term changes in scenic beauty attributable to the

forest treatments were computed from these ratings. High visual impacts meeting very low scenic integrity standards were

observed for clearcuts, 15-percent aggregated-retention harvests of mature forests, and 15-percent mixed-pattern retention

harvests of old growth. Moderate impacts meeting low scenic integrity standards were observed in 40-percent aggregatedand 15-percent dispersed-retention harvests of mature forests. Both thinnings produced low impacts meeting moderate scenic

integrity standards. Treatments of 40-percent dispersed and 75-percent aggregated retention produced low impacts that can

meet high scenic integrity standards. Some green-tree retention harvests have clear value in meeting aesthetic goals in forest

management.

KEYWORDS: Scenic beauty, timber harvests, public perceptions, green-tree retention.

137

derive scenic beauty prediction models from which the visual

impact of forest changes might be computed or inferred.

The state of the art in scenic impact assessment emphasizes evaluation of scenic change over time against visual

standards that describe acceptable amounts of change in

different places. The standards used by the USDA Forest

Service consist of five “scenic integrity levels” ranging

from “very low” to “very high,” with higher levels typically

applied to more scenic, seen or valued landscapes (USDA

FS 1995). Scientific evidence is needed to inform these

assessments.

Study Objectives

This study investigated visual-aesthetic change inside

forests as a result of harvests and thinnings in western

Oregon and Washington. It investigated the worst-case,

short-term impacts of recently conducted harvests. These

impacts often need the most attention in improving social
perceptions of forestry (Sheppard 2001). An investigation

of green-tree retention harvests was emphasized because

these are gaining attention (Franklin et al. 1997) and need

to be compared to more traditional and sometimes aesthetically controversial harvests. Changes in scenic beauty

because of clearcuts, thinned forests, and an old-growth

harvest were, therefore, compared to green-tree retention

harvests.

Numerous photo points were established inside experimental forests throughout western Washington and Oregon.

The same scene was photographed from all of these points

before and after the various harvests. A sample of these

pairs of replicated photos were rated for scenic beauty by

public respondents. Estimates of changes in average perceived scenic beauty ratings were found. These were compared to assess which treatments tend to produce which

visual impact levels. The same changes in beauty were also

compared against acceptable changes indicated by visual

integrity standards used by the Forest Service in landscape

planning (USDA FS 1995).

Background

Green-tree retention harvests are proposed by “New

Forestry” (Franklin 1989) as alternatives to clearcutting.

The goals of such alternatives are generally perceived more

positively than conventional forestry by placing more emphasis on sustaining ecological health (Ribe and Matteson 2002).

When viewed from inside the forest, green-tree retention

harvests have aesthetic potential (Brunson and Shelby 1992),

but not all aspects of such ecologically-derived harvest prescriptions will be necessarily aesthetically successful (Gobster

1996). Much may depend on how they manifest the “violence” of harvesting (Benson and Ullrich 1981). Scenic

impacts, as a result of various forest harvests, should be

compared to an old-growth harvest. Harvesting old growth

forests is controversial in the Pacific Northwest, in part

because of the loss of aesthetic values (Brunson and Shelby

1992).

To the extent that green-tree retention harvests leave

more standing trees than most traditional harvests, they

should be more aesthetically successful (Buhyoff et al. 1986,

Schroeder and Daniel 1981, Vodak et al. 1985), although

too few trees can be left standing (Daniel and Boster 1976,

Schweitzer et al. 1976). Retaining more large green trees

should aid aesthetic value (Brown and Daniel 1986, Daniel

and Boster 1976, Schroeder and Daniel 1981).

Forest thinnings tend to be aesthetically preferred to

other forest harvests, provided that down wood is removed

(Kenner and McCool 1985), not too many trees are removed

(Vodak et al. 1985), and larger trees are retained (Buhyoff

et al. 1986). Thinned forests, after they regain ground vegetation, can be preferred to unmanaged forests of the same

age (Bradley et al. 2004, Brush 1979).

METHODS

Study photographs came from the Demonstration of

Ecosystem Management Options (DEMO) study (Aubry et

al. 1999), the Long-Term Ecosystem Productivity (LTEP)

study (Homann et al. 2001), and the Young Stands Study

(YSS) (Hunter 2001, Kellog et al. 1998). These studies are

all forest harvest experiments conducted in conifer-dominated forests in western Washington and Oregon. All are

randomized block designs with harvest treatments replicated at locations exhibiting various altitudes and forest

conditions.

The nine forest treatments investigated here were drawn

from the three studies listed above. These are listed across

the bottom of figure 1 and were implemented in forests

outlined below.

The DEMO study provided examples of 15-, 40- and

75-percent retention harvests. The DEMO harvest sites were

reasonably representative of mature, coniferous forests on

public lands in western Washington and Oregon. The forests

at the six DEMO blocks were between 65- and 170-years

old and dominated by Douglas-fir (Pseudotsuga menziessi

(Mirb.) Franco). The DEMO blocks included one on a

level site, one on moderate slopes of 9 to 33 degrees, two

mostly on moderately steep slopes of 40 to 53 degrees, and

two mostly on steep slopes of 50 to 66 degrees. These slopes

were relatively even within most of the units at all blocks.

Four blocks contained pretreatment stands with densities

mainly in the 200 to 500 trees/ha range, and the other two

had mainly 700 to 1300 trees/ha. The basal area of the

DEMO forests fell mostly in the 40 to 90 m2/ha range with

the mature cohort of trees typically at 38 to 76 cm, 1.37 m

above ground (d.b.h.). One block had little ground vegetation and understory with extensive visual penetration. The

other five pretreatment forests had ample ground vegetation

and were typically heterogeneous enough to include areas

of understory and limited visual penetration. (See Aubry et

al. (1999) and other articles in this report for greater detail

about the DEMO forests.)

The DEMO treatment units were 13 ha and square or

slightly rectangular. For the aggregated-retention treatments,

the percentage of retention was by area of the unit. For dispersed retention treatments, the percentage of retention was

by basal area to match that of the corresponding percentage,

138
aggregated-retention treatment within the corresponding

block. The 15-percent aggregated-retention treatments contained two 1-ha, 56-m diameter, circular aggregates of uncut

forest near opposite corners of the unit. The 40-percent

aggregated-retention treatments contained five aggregates

of the same size and shape, arranged in a dice-shaped pattern (illustrated in other articles in this report). This unnatural geometry of the retention aggregates was for scientific

purposes related to other studies. It was not obvious when

seen from inside the units and even less detectable in the

photographs used for this study.

One LTEP block of four replicates (near Sappho,

Washington) provided example clearcuts for comparison 

to the DEMO and YSS retention harvests. The LTEP block

also provided an example of a 40-percent dispersed-retention harvest, by basal area (50 percent by tree density) that

was employed in this study. Prior to harvesting, this block

contained a 70-year-old, second-growth forest dominated

by Douglas-fir on level ground. This block contained pretreatment stands with densities in the 700 to 800 trees/ha

range. The basal area of these forests fell mostly in the 55

to 70 m2/ha range, with the mature cohort of trees typically

at 38 to 51 cm d.b.h. The clearcuts units in the LTEP study

were 6 ha and square or slightly rectangular.

Four YSS blocks in the Willamette National Forest of

Oregon provided examples of thinned young forests. Each

of these included a light thin retaining a dispersed pattern

of 50 percent stems, and a heavy thin retaining 25 percent

dispersed stems. Hardwoods were retained as much as possible. Prior to thinning, these blocks contained 30- to 50-

year-old, even-aged forests dominated by Douglas-fir. The

YSS blocks included one on a level site and three on moderate slopes of 9 to 24 degrees. These YSS blocks contained

pretreatment stands with densities in the 500 to 800 trees/ha

range. The basal area of these pretreatment forests fell mostly

in the 20 to 25 m2/ha range, with the trees typically at 25

to 31 cm d.b.h. The YSS thinning units varied from 14 to

53 ha and occurred at altitudes from 134 to 276 m.

An old-growth harvest was included in the study for

comparison. This entailed photo sampling from two different sites. Pretreatment photographs (n=48) came from oldgrowth forests on the Umpqua National Forest of Oregon

that were sampled for the DEMO study but not harvested.

Corresponding post-treatment photographs came from a

recent old-growth harvest in the same national forest, as

described later. This old-growth harvest followed Northwest

Forest Plan standards (USDA and USDI 1994). It contained

15-percent density retention roughly split between aggregates

139

Figure 1—Observed changes in scenic beauty due to forest treatments.
and dispersed trees elsewhere in the unit. Down wood was

mostly removed except for scattered, large logs.

Field Photography

Permanent monuments were driven into the ground

within every treatment unit in all three studies. These were

laid out in grids in the DEMO and LTEP units, and along

transects in the YSS units. In all cases, the array of monuments was small and roughly centered within each unit so

that photographs from monuments mainly captured the corresponding treatments. Predetermined subsets of monuments

served as photographic sampling points, with care taken to

ensure unbiased representation of the scenery. These points

were located by protocols determined prior to field inspection of the forests or knowledge of how the monuments

would fall within the forest structure and terrain. All photographs were replicated, once before treatment and once

within 3 months after treatment.

All photographs were taken from sampling monuments

in specified directions using a 35mm SLR conventional

camera with a 35mm lens. The horizon, or estimated horizon

if invisible, was placed one third of the way up each image,

even when photographs were taken up or down slopes. For

side slopes, the horizon point at the center of the image

followed this rule. If a tree, shrub or rock obstructed a prescribed photo, the photographer moved up to 1 m in the

shortest possible direction to minimize the obstruction in the

photo. Photos were taken within 3 hours of noon, standard

time.

A standard pattern of eight photos was taken in each

DEMO unit from monuments along the edges and at the

corners of the grid, all aimed at the center of the grid. This

yielded 48 photo replicate pairs for each DEMO treatment

across the six blocks. This pattern of photos was designed

for representative post-treatment sampling of the most

scenically-complex, 40-percent aggregated-retention treatment. The pattern of photos was designed by reference to

the pattern of future felling for that treatment that was fixed

in advance in relation to the grid of monuments. The resulting set of post-treatment scenes captured a variety of views,

i.e., views inside uncut aggregates, across larger areas of

harvested matrix, looking at unharvested matrix between

uncut aggregates, and views of nearby aggregates with harvested matrix in the foreground. This mix of sample photos

sought to capture views similar to those encountered on 

a random hike through this treatment. The other DEMO

treatments were homogeneous enough for the same photo

pattern to representatively sample scenery there as well.

A standard set of five points within the LTEP units were

sampled. Photos were taken from each of these in the four

cardinal compass directions. This yielded 20 photos per

treatment unit. There were 16 clearcuts in the Sappho LTEP

block employed in this study. This yielded 320 photos for

clearcuts. There was also one dispersed retention harvest

unit in the same block that met the same 40-percent, dispersed-retention basal area as one of the DEMO treatments

being studied, yielding 20 more sample photos of that

treatment.

Photographs were taken within each YSS unit from four

randomly selected monuments. Photos were taken at each

in the four cardinal compass directions. This yielded 16

photos per unit, or 64 photos per treatment across the four

YSS blocks.

Twelve photographs inside old-growth forests were 

randomly selected. Copies of these were taken into the

Umpqua National Forest old-growth harvest described

above. Photos of this old-growth harvest were found and

taken to match the untreated old-growth photos as closely

as possible with respect to slopes and the position of stumps

and standing trees within the photo frames. This method

served to produce photos that were plausible as “post-treatment replicates” of the pretreatment old-growth photos. This

yielded 12 pairs of replicated photos for this constructed

example of an old-growth harvest.

Controlling for Down Wood in Photos

Because down wood left after harvest adversely affects

scenic beauty perceptions (Brown and Daniel 1986, Daniel

and Boster 1976, Schroeder and Daniel 1981, Schweitzer et

al. 1976, Vodak et al. 1985), it needed to be controlled for

in photos used in public surveys. To represent down wood

similarly within all treatments’ photo samples, half of each

treatment's post-treatment photos were sampled to exhibit

a high level of down wood. The pairs of replicated photos

that included high post-treatment down wood needed to be

separated out prior to final sampling for public surveys.

This was done according to different rules depending on

the study from which the photos came.

High down wood LTEP and YSS post-treatment photos

were those taken of units where most harvest residue, including tops, limbs, and many logs remained on site. This was 

a prescribed, permanent condition in half the LTEP clearcut

units photographed (n=160 photos) and the one 40-percent

dispersed retention LTEP unit (n=20). In one of the YSS

blocks, high down wood photos were taken before harvest

residue were cleaned up (n=16 photos in each of the two

140
treatments). In the other three YSS blocks (n=48 photos per

treatment), low down wood photos were taken after harvest

residue was removed.

High down wood post-treatment photos from the DEMO

treatments were identified according to field measurements

of the area depicted within the photos. Threshold values of

total down wood per hectare were used. These were derived

from sample-based estimates of the volume per hectare of

course wood, course litter, and snags leaning more than

15o. The course wood (>10 cm diameter) estimates came

from the 6-m transect shown in the photo and closest to the

photo point. The course litter (5-10 cm diameter) estimates

came from six 0.2-ha x 0.5 m microplots along the same

transect. The leaning snags estimate came from the 0.08-ha

circular plot shown in the photo and closest to the photo

point. Leaning, dead trees, not rooted vertical ones, are more

likely to adversely affect beauty perceptions (Brunson and

Shelby 1992, Brush 1979).

The threshold values were as follows: among photos that

depicted a foreground of 15-percent dispersed retention, or

of harvested matrix within any aggregated retention treatment, those with more than 300 m3/ha of down wood were

classified as high down wood. For photos that depicted 40-

percent dispersed retention harvests, the threshold was 200

m3/ha. If a photo depicted unharvested aggregate in the

foreground, the threshold value was 100 m3/ha.

Sampling of Photos for Public Surveys

A subsample of the pairs of replicated photos (the same

scene taken before and after forest treatments) was selected

to represent each such treatment in public surveys. The

number of photos sampled needed to reliably represent the

scenic variability encountered within forests produced by

any one treatment (Palmer and Hoffman 2001). To identify

this sample size, public surveys were conducted in stages,

each adding more photos until a reliable sample size was

found. The first stage included eight pairs of replicated

photos from each treatment. Additional stages added four

more of these photo pairs from each treatment. The reliability test after each survey stage was the standard error of

the mean perceived scenic beauty value (described later)

among the post-treatment scenes for every treatment. Only

the samples of the post-treatment scene were tested because

they had more variability in scenic beauty ratings. These

test values estimated the variability expected in mean scenic

beauty found among other samples of the same number of

scenes that might be sampled for each treatment. Once the

test values for all treatments fell below 10 percent of the

full range of perceived scenic beauty observed in the study,

the photo sample size was deemed reliable. This occurred

after two survey stages, at a final sample size of 12 pairs of

replicated photos per treatment.

Some photo replicate pairs were eliminated before final

subsampling for the public surveys. These were instances

where one or both of the photos in each pair had one of

four problems: (1) very poor photographic quality; (2) too

much plastic flagging in the immediate foreground (placed

by field researchers); (3) a close-up obstruction filling more

than 25 percent of the photo; or (4) taken close to and toward

the edge of a treatment unit, so that the wrong surrounding

forest or neighboring treatment was depicted. This screening eliminated 9 percent of DEMO, 16 percent of LTEP,

and 11 percent of YSS photo pairs.

For the first stage of public surveying, four pairs of

replicated photos showing higher amounts of down wood,

and four other photo pairs showing lower amounts of down

wood were randomly selected for each treatment, yielding

eight total photo pairs per treatment. The same procedure

was used for the second stage, except two pairs per down

wood level per treatment were selected. This yielded a total

final sample of 12 (8+4) photo pairs per treatment.

Public Perception Surveys

All photo replicate pairs for all treatments were placed

into a mail or live-group survey instrument. (Two survey

protocols were employed due to funding limitations and the

need to keep surveys short enough to elicit high response

rates.) For the first stage survey, two randomly selected

post-treatment photos of each treatment were allocated to

the mail survey. This mail survey also included single, randomly-selected, pretreatment photos of a young forest, a

mature forest, and an old-growth forest, as well as forestry

attitude questions. All remaining first-stage photos were

allocated to a survey of live groups described below. Care

was taken to insure the comparability of the survey samples,

as described later.

The mail survey photographs were printed in color, in

random order, eight to a page, in an 28 x 43 cm (11 x 17

in) fan-fold survey. A random sample of 1,669 residents of

western Washington and Oregon received letters requesting

participation. Of these, 698 volunteered by returning postcards affirmatively as the compliant sample to whom the

survey was sent. Two prompting letters were sent at successive twelve day intervals. In all, 647 returned the survey

for a 93-percent response rate within the compliant sample,

or 39 percent of the original sample.

141
Respondents were instructed that the photos included

examples of forests with and without various timber harvests.

They were instructed to rate the scenes for scenic beauty

on a numeric scale from -5 to +5, ranging from “very ugly”

(-5) to “very beautiful” (+5), with zero value ratings

assigned to photos they found neither beautiful nor ugly or

were undecided about.

The photos not allocated to the mail survey were projected as slides for rating by groups as an activity during

their regular meetings. The groups included service clubs,

higher education classes, outdoor interest groups, and business clubs representing economies significantly dependent

on timber harvesting. These respondents were given the

same instructions, and used the same rating scale. Each

respondent rated the slides privately on their own survey.

The photos were projected in random orders, and each

slide was shown once for 7 seconds.

Six of the photo replicate pairs from each treatment,

plus the pretreatment photos not included in the mail survey,

were allocated to the first-stage, live-groups survey. Fifteen

groups participated in this first stage, providing 271 respondents. Four additional photo replicate pairs from every forest treatment were in the second-stage, live-groups survey.

Ten groups participated in this stage, providing 210 respondents. A few of the meeting attendees elected not to participate, and were not tracked, so a response rate can not be

reported.

The live group slide rating surveys constituted a less

random sample of the public than the mail survey. The most

likely difference in rating bias between these two samples

came from a significant difference in their representation of

forest protection versus forest production attitudes. The

ratings of these two categories of respondents was strongly

correlated but with significantly different average values

due to different aesthetic standards (Ribe 2002).

Accordingly, various live groups were recruited seeking

a respondent sample with overall attitudes toward timber

harvesting like that from the mail survey. The mail survey

was completed first, yielding its distribution of attitude

questionnaire responses. Live groups of respondents were

recruited to roughly duplicate this distribution of environmental biases, as suggested by their defining mission or

common interest. Groups' expected attitudes toward timber

harvesting were also anticipated according to their urban

versus rural location (Hansis 1995, Tremblay and Dunlap

1978), their members' typical length of residence in the

region (Xu and Bengston 1997), and gender balance (Hansis

1995, Levine and Langenau 1979).

Measuring Perceptions

A scenic beauty estimate (SBE) was computed for each

scene from all its ratings (Daniel and Boster 1976). This

method of averaging ratings removes differences in how

respondents distribute their ratings along the scale, and

thereby standardizes just their perceptions of relative beauty.

In this study, the respondents used a bipolar rating scale,

producing SBE values that took on both positive and negative values, scaled to a zero point where the average respondent changed from negative (ugly) to positive (beautiful)

ratings (Ribe 1988).

RESULTS

The changes in average SBE values across the photos

representing each treatment are graphed in figure 1. All

treatments produced reductions in scenic beauty. Consequently,

the top of each arrow in figure 1 indicates the average SBE 

of the pretreatment photos, and the bottom indicates the

average of the post-treatment photos. Inspection of the top

of the arrows suggests an increasing trend in pretreatment

scenic beauty from young to mature to old-growth forests.

Within that pattern there was some chance variability in the

level of SBEs observed in the pretreatment forests assigned

to different treatments.

Inspection of figure 1 indicates several results regarding

the position of different treatments' scenic beauty changes

within the range of observed SBE levels. The two levels 

of thinning both produced similar reductions in SBEs such

that the difference in their post-treatment SBEs may be

accounted for by the chance difference in their pretreatment

SBEs. Treatments of mature forests exhibited an increasing

trend of post-treatment SBEs with increasing levels of

green-tree retention. Within single retention levels (15 or

40 percent ), dispersed retention produced higher post-treatment SBEs than aggregated retention. The dispersed 40-

percent and aggregated 75-percent retention treatments

produced positive post-treatment SBEs, while all the other

mature forest treatments produced negative post-treatment

SBEs. The 15-percent retention treatment of old-growth

produced a change from the highest observed pretreatment

SBE to a moderately negative post-treatment SBE.

Inspection of figure 2 indicates results about the comparative magnitude of scenic beauty changes due to the

treatments. Figure 2 shows differences in scenic impact

ordered by absolute change in average SBEs. All pairs of

these SBE changes were tested for statistically significant

differences using t tests, at p = 0.05. The sets of scenic

impacts that are not statistically different are indicated by

the bars across the top of figure 2. Note that the magnitude

142
of average SBE change for the 75-percent aggregatedretention harvest was much smaller than all the other treatments (fig. 2). However, this obscures variation in SBE

changes encountered within its various pairs of replicated

photos between patches of harvested matrix versus unharvested aggregates. This variation produced a large enough

standard deviation in SBE change values to cause it to be

statistically the same as the other three treatments at the

right of figure 2.

FINDINGS

The three sets of statistically-the-same absolute changes

in scenic beauty in figure 2 indicate three short-term, in-stand

scenic impact levels. These are generic, evidence-based

levels useful for assessing impacts widely, as in forest plans

and watershed analyses. At the level of a single harvest,

landscape architects may marginally modify these impacts

based on the design of each project:

• High impacts = clearcuts.

• High to moderate impacts = old-growth harvests 

executed under guidelines from the Northwest Forest

Plans and 15-percent aggregated-retention harvests in

mature forests.

• Moderate impacts = harvests of mature forests that 

employ 15-percent dispersed retention or 40-percent

aggregated retention.

• Low impacts = thinnings and mature-forest harvests 

employing 40-percent dispersed or 75-percent aggregated

retention. The latter can produce very low impacts if the

harvested patches are placed out of view.

A comparison of the magnitude and position of scenic

changes in figure 1 allows generic comparison to what

would be acceptable, low impacts at various visual integrity

levels:

• Clearcuts and 15-percent aggregated retention harvests

produce very large changes from strongly beautiful to

strongly ugly, consistent with low scenic impacts only

against the "very low" scenic integrity standard.

• Old-growth harvests executed under the guidelines of

the Northwest Forest Plan also fall into this “very low”

scenic integrity standard. They produce changes from

strongly very beautiful to moderately ugly, a more than

moderate change incompatible with preharvest natural

landscapes.

• 15-percent dispersed and 40-percent aggregated-retention harvests produce large changes from strongly beautiful to moderately ugly, consistent with low scenic

impacts only against the “low” scenic integrity standard.

• Thinned young forests, whether heavy or light, produce

short-term changes from moderately beautiful to moderately ugly, consistent with low scenic impacts against

143

Figure 2—Comparing magnitudes of changes in scenic beauty due to forest treatments.
the “moderate” scenic integrity standard. These are

slight scenic changes that tend to be visually subordinate

to continued, intact forest scenery.

• 40-percent dispersed and 75-percent aggregated-retention harvests produce changes from strongly beautiful to

moderately beautiful forest, consistent with low visual

impacts against the “high” scenic integrity standard.

They maintain the positively beautiful forest landscape.

Further research is needed regarding longer term scenic

impacts of these and other alternative timber harvests

(Shelby et al. 2003), and how perception of such harvests

differs among people with different knowledge of the 

values and risks each entails (Bradley et al. 2004).

ACKNOWLEDGMENTS

This study was supported by the Demonstration of

Ecosystem Management Options (DEMO) project, a joint

effort of the USDA Forest Service, Region 6 and Pacific

Northwest Research Station. Research partners include the

University of Washington, Oregon State University, University of Oregon, Gifford Pinchot and Umpqua National

Forests, and the Washington State Department of Natural

Resources. It was also supported by the Long Term Ecosystem Productivity and Young Stand Thinning and Diversity

Studies of the USDA Forest Service, Region 6.

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1 Research Assistant and 2 Professor, Department of Forest Ecosystem Sciences, University of Maine, 5755 Nutting Hall, Orono, ME 04469-5755, USA.

Email for corresponding author: mike_saunders@umenfa.maine.edu

Balancing Ecosystem Values Proceedings, Regional Experiments

Ten-Year Results of the Forest Ecosystem 

Research Program – Successes and Challenges

Mike R. Saunders1 and Robert G. Wagner2

INTRODUCTION

Silviculture is inherently a long-term proposition. Dynamics within forests exist on temporal scales of decades to

centuries; therefore, any impacts that silvicultural prescriptions have must be measured over similar periods of time.

Prescriptions that convert a stand from a tree species assemblage or a particular age structure to another may need even

longer time frames for evaluation. Long-term, replicated

research documenting the effects of silvicultural prescriptions

is rare, particularly in the Acadian ecoregion of northern New

England and the Canadian Maritime Provinces.

The Forest Ecosystem Research Program (FERP) is 

one attempt to fill this void. FERP was initiated partially in

response to the “New Forestry” paradigm that began in the

late 1980s in the Pacific Northwest and that Seymour and

Hunter (1992) later developed into the Triad concept of

ABSTRACT

The Forest Ecosystem Research Program (FERP) was initiated by the University of Maine in 1993 on the Penobscot

Experiment Forest in Bradley, Maine. FERP is comparing three expanding-gap silvicultural treatments designed to emulate

the 1-percent natural disturbance frequency common within the Acadian ecoregion: (1) 20-percent canopy removal on a 10-

year cutting cycle (creating 0.2-ha openings) with 10 percent of the basal area retained as permanent reserve trees and a 50-

year rest period following the first five cycles; (2) 10-percent canopy removal on a 10-year cycle (creating 0.1-ha openings)

with 30 percent of the basal area retained as permanent reserve trees and no rest period, and (3) an unharvested control. The

treatment plots are roughly 10 ha in size and replicated three times in a randomized complete block design. The study has

provided a template for examining a variety of ecological questions related to gap disturbances. Gap harvesting influenced

the volume and biomass of downed woody debris (DWD) and increased vegetation abundance and diversity relative to natural gaps and undisturbed canopy. Although avian communities were largely unaffected by gaps, amphibian and arthropod

communities showed variable species-specific responses, often in association to changes in DWD volumes. Challenges to

maintaining long-term ecological studies of this type include continuity of funding and researchers, shifts in project scope

and objectives, data management, and site coordination among research teams.

KEYWORDS: Alternative silviculture treatments, expanding gaps, Acadian ecoregion, long-term experiments, Maine.

147

forestland allocation. Under the Triad concept, land was

allocated to three primary uses: (1) 10 to 20 percent of the

landbase was allocated to a system of representative reserves

intended to address biodiversity concerns and provide a

benchmark for comparisons with managed forests; (2) 10

to 20 percent of the landbase was dedicated to high-yield

silviculture, partially to offset the timber production capacity lost to reserves; and (3) the remainder of the landbase

was to be managed extensively by using silvicultural systems designed to emulate natural disturbance regimes (see

Seymour, this volume). The Triad concept was appealing.

Land managers and conservationists could promptly identify reserve areas and silviculturists could easily design systems that would lead to higher yields. Furthermore, the

long-term (>50 years) silvicultural research by the USDA

Forest Service at the Penobscot Experimental Forest (PEF)

provided some guidance on how traditional even-aged and
uneven-aged silvicultural systems might be applied to portions of the landbase (Brissette 1996). Unfortunately, the

Triad concept lacked scientific rigor for application. Many

of these traditional systems had inherent weaknesses that

could make them infeasible or impractical for broader management of the matrix. For example, many even-aged systems, although economically appealing, could not adequately

create the stand structure that would mimic the gap-driven

natural disturbance regimes of the Acadian ecoregion.

Selection systems might create this structure, but often they

were unwieldy in application, expensive, and in some respects,

as artificial as even-aged systems. Research with hybrid

silvicultural systems, those combining the strengths of both

even-aged and uneven-aged systems, was needed.

In 1994, a group of faculty members from the University

of Maine received a 5-year grant from the Maine Agricultural

and Forest Experiment Station to help fill this knowledge

gap. Funding for FERP beyond the initial 5 years continued

at the discretion of the Dean of the College of Natural

Sciences, Forestry, and Agriculture at the University of

Maine. Once established, FERP also provided a foundation

upon which extramural grants were developed and research

projects superimposed. 

FERP treatments include two versions for expandinggap silvicultural systems that are long-term in scope (i.e.,

100 years) and emulate 1-percent disturbance intensity.

FERP has three scientific goals:

1. Explore the potential for developing alternative 

silvicultural techniques and systems based on 

regional disturbance ecology

2. Evaluate ecosystem-scale influences of forest 

practices

3. Enhance understanding about forest ecosystems 

in the Acadian ecoregion

This paper reviews the first 10 years of FERP, including

the experimental design and inventory of the treatments and

significant findings from some of the research conducted at

the study sites. We conclude with a discussion of planned

future activities and the potential challenges faced by this

long-term project.

METHODS

Study Area

The FERP study areas are located with the Penobscot

Experimental Forest (PEF) near Bradley, Maine (lat 44°

52’ N, long 68° 38’ W). This 1550-ha research forest is

owned by the University of Maine Foundation and managed conjointly by the University of Maine and the USDA

Forest Service, Northeast Forest Experiment Station (fig.

1). This forest lies on soil types derived from glacial till

and ranging from well-drained loams and sandy loams on

glacial till ridges to poorly and very poorly drained loams

and silt loams in flat areas between the ridges (Brissette

1996). Cover types are dominated by Acadian Region softwoods including red (Picea rubens Sarg.), white (P. glauca

(Moench) Voss) and black spruce (P. mariana (Mill.) B.S.P.),

balsam fir (Abies balsamea (L.) Mill.), eastern white pine

(Pinus strobus L.), eastern hemlock (Tsuga canadensis (L.)

Carr.), and northern white-cedar (Thuja occidentalis L.).

Common hardwoods in these types include red maple

(Acer rubrum L.), paper (Betula papyrifera Marsh.) and

gray birch (B. populifolia Marsh.), and quaking (Populus

tremuloides Michx.) and bigtooth aspen (P. grandidentata

Michx.). Natural stand structures in this region are typically

uneven-aged and quite diverse with windstorms and insect

epidemics as the major disturbance events (Seymour 1992).

Stand replacing fires are thought to occur less than once

per 1000 years in these types (Lorimer 1977). Overall,

disturbance intensities are estimated to be no more than 

1 percent per year (Runkle 1982).

148

Figure 1—Location of the Forest Ecosystem Research Program research

areas (RA) within the Penobscot Experimental Forest in Bradley, Maine.

Block 1 (consisting of RAs 1-3) was initially harvested in winter 1995-

1996, block 2 (RAs 4-6) was harvested winter 1996-1997, and block 3

(RAs 7-9) was harvested winter 1997-1998. Permanent roads are shown

with solid lines; dotted lines indicate streams.
Experimental Design

The FERP study was established between 1995 and

1998 across nine 9.4- to 11.3-ha research areas within hardwood-dominated mixed wood sites on the PEF. The design

is a randomized complete block with three replicates each

of two silvicultural treatments and an unharvested control,

blocked on the year of winter harvest (fig. 1). The two 

silvicultural treatments were derived from the German

Femelschlag or expanding-gap silviculture (fig. 2a). The

heavier “20-10” treatment removed approximately 20 percent of the canopy at each entry (range: 19.5 to 21.3 percent, assuming 5 m wide skid trails), with 10 percent of the

basal area permanently reserved. The lighter “10-30” treatment removed 10 percent of the canopy each entry (range:

6.2 to 13.8 percent), with 30 percent of the basal area permanently reserved. Both treatments have 10-year cutting

cycles, 100-year rotations, and emulate 1-percent disturbance intensity; the 20-10 treatment differs by concentrating

harvest activity within the first 50 years and then allowing

the stand to rest for the second half of the rotation (table 1).

Natural gaps and current age structures are used to help

adjust cutting levels; for example, the 10-percent goal in

one replicate of the 10-30 treatment was adjusted downward

because of a large patch of very young (<20 yr) regeneration that existed in a significant portion of the stand. Harvests

should create quite diverse age structures and canopy conditions as successive gap expansions regenerate new cohorts

of individuals (fig. 2b). Reserve trees, selected to protect

rare species, maintain species diversity, improve species

and genetic composition of regeneration, retain or increase

wildlife value of stand (i.e., current cavity trees or future

large-diameter downed woody material), and/or greatly

increase in value over an extended rotation (e.g., white pine),

would add further structural complexity to the resulting

stand (fig. 2b). After one rotation, the surviving reserve trees

from the initial harvest are either selected for continued

reserve, or harvested and replaced with newly selected

reserves.

Within each research area, two sets of inventory plots

are used. The first set is designed to inventory overall treatment effects on stand conditions (i.e., growth and yield of

the resulting stand). Twenty 0.05 ha fixed area, circular

inventory plots were randomly chosen from the intersection

points of a 50 m x 50 m grid laid across each research area.

All overstory trees (>9.5 cm d.b.h.) and deadwood (>9.5 cm

small-end diameter) are inventoried. Nested within, saplings

(>1.5 cm d.b.h.) and all seedlings/herbaceous species are

inventoried with 0.01 ha fixed area, circular plots and four

1 m2 quadrats, respectively. Light conditions also are measured within the plots using the LAI-2000 Plant Canopy

Analyzer (LI-COR 1992). The second set of inventory

plots assesses treatment effects on vegetation dynamics and

development of the regeneration within harvested gaps. In

both natural (as in control research areas) and harvested

gaps, transects were laid along the longest north-south axis.

Along each transect, 2 m x 2 m quadrats are placed every 

4 m, starting at 2 m north and 2 m south of gap center, and

extending to the edges of the gap. Abundance and cover of

all herbaceous and woody species, basal area of the residual

canopy and light levels are measured in each quadrat.

Further details of sampling protocols are available from 

the authors.

RESEARCH FINDINGS

The FERP harvest treatments created diverse canopy

conditions that have provided numerous graduate students

and scientists with opportunities to investigate the effects

of gap creation on the forest biota. A major emphasis of

this research has been the quantification of harvest effects

and interactions between downed woody debris (DWD;

Fraver et al. 2002), terrestrial amphibians (Strojny 2004),

and forest arthropods (Thomas, n.d.). Other studies have

examined gap influences on herbaceous vegetation and tree

regeneration (Schofield 2003), and bird communities (Hartley

2003). The FERP research areas also have been invaluable

for teaching and outreach at the University of Maine.

149

Table 1—Description of the three treatments being studied within the Forest Ecosystem Research

Program at the Penobscot Experimental Forest in Bradley, Maine

Disturbance Permanent Cycle for complete Compositional

Treatment intensity (yr-1) retention tree regeneration goal

20-10 2% (first 50 yr) 50 yr

0%(second 50 yr) 10% basal area (w/ 50 yr rest) mid-successional

10-30 1% 30% basal area 100 yr late-successional

Control natural 100% basal area natural natural succession
Downed Woody Debris

Preharvest volume and biomass levels of DWD were

approximately 109.1 m3/ha and 23.2 Mg/ha, respectively

(Fraver et al. 2002). Initial gap harvesting contributed a

pulse of small-diameter, less-decayed pieces into the DWD

distribution, with the 20-10 treatment adding significantly

more than the 10-30 treatment (p = 0.069). Fraver et al.

(2002) also suggested that temporal development of DWD

in many Acadian Region forests may not follow the typical

U-shape that has been reported elsewhere, often in much

more even-aged systems.

Nutrient analysis of this work (Saunders, n.d.) indicates

that DWD from hardwood species generally had higher

nutrient content than from softwood species in comparable

decay classes. Not surprisingly, preliminary results suggest

that harvesting shifts nutrient loads from live biomass to

less decayed DWD classes. However, as in many forest

communities in the Acadian Region, the nutrient loads in

DWD are insignificant compared to those in living tree

biomass and soil pools (Fernandez 2004). Therefore, it is

unlikely that the shift of nutrients to DWD from harvest

constitutes a significant change in nutrient pools or imposes

any limitations on forest productivity at the site scale.

Terrestrial Amphibians

Most terrestrial amphibian species studied on FERP

research areas have not been influenced by natural or harvested forest gaps. Strojny (2004) studied amphibian communities using pitfall trap arrays over 2 years and 250,000

trap nights. She concluded that of 12 species, only juvenile

and adult spotted salamanders (Ambystoma maculatum

Shaw) showed a consistent, negative population response

to gaps. However, she did find during active searches of

moderately-decayed class II-III logs under a closed forest

150

Figure 2—Hypothetical example of the 20-10 harvest expanding-gap treatment. Each entry removes 20

percent of the area, leaving 10 percent of the basal area in reserve trees (fig. 2a). The expected structural

development of the stand after entries 1, 3, and 5 (fig. 2b) marked by the heavy black line in figure 2a is

quite complex and diverse, consisting of multiple cohorts and canopy layers of trees and reserves. The

existing skid trail network is shown as light black lines in figure 2a.
canopy that northern red-backed salamanders (Plethodon

cinereus Green) were present in about 40 percent of all

logs greater than 10 cm diameter (small-end). In gaps, the

detection rate varied by log size, ranging nearly linearly

from about 6 percent for 10 cm logs to over 50 percent for

45 cm logs. This suggested that salamanders shifted their

habitat preference to larger diameter logs in response to the

harvest gaps. This observation is similar to one by Mathis

(1990), who found that red-backed salamanders preferred

larger cover objects that would buffer them against extreme

temperatures.

Forest Arthropods

In one of first large-scale studies of forest click beetle

(Family: Elateridae) communities, Thomas (n.d.) investigated the interactions among harvested gap size and DWD

on click beetles. As of the 2002 field season, 42 species

have been identified, five of which were unknown to science. Preliminary results suggest that although the click

beetle community as a whole occupied the full size range

and all decay classes of DWD present, most species were

specialists in terms of DWD size (diameter), DWD decay

class, and/or harvest gap size—even those species reported

as generalists elsewhere in the literature. Harvests had

species-specific effects on the community, usually through

its influence on the DWD distribution. Overall, soil emergence of click beetles (individuals/m2) was higher in nongap areas (p<0.01) versus gap areas of the same harvest

treatment, but the different silvicultural treatments themselves were not significant (p = 0.84). This indicated that

click beetle community responded negatively to the presence

of any gap, whether or not that gap was natural or harvested.

With the exception of two species, DWD diameter had no

effect on click beetle emergence from logs. Decay class 

of DWD did affect beetle emergence, however, with more

beetles emerging from well-decayed class IV logs than from

moderately-decayed class II logs (p = 0.03; Thomas, n.d.).

Gap Vegetation and Tree Regeneration

Gap harvests influenced herbaceous community dynamics and had mixed effects on tree regeneration. Schofield

(2003) reported that although larger, harvested gaps (>500

m2) had greater average percentage of cover and overall

plant species richness, diversity and evenness indices did

not differ between smaller gaps, either harvested or natural,

and closed-canopy conditions (p = 0.74 and p = 0.72, respectively). The most significant change in plant communities

was an increase in the abundance of ruderal and exotic

invasive species in the gaps of the 20-10 treatment.

Although the FERP harvests had no significant effect on

total number of regenerating trees (p = 0.15), they did cause

a shift in species dominance (Schofield 2003). Harvested

gaps tended to have higher numbers of red maple and paper

birch in all height classes. Conifers dominated the natural

gaps more, with balsam fir, eastern hemlock, and eastern

white pine being the predominate species. Regeneration

under closed canopies was more indicative of the overstory

species, with balsam fir, red and sugar maples (Acer

sacharrum Marsh.), and eastern hemlock more common,

particularly in the larger height classes (>2.0 m tall)

(Schofield 2003).

Forest Bird Communities

Hartley (2003) studied the response of the forest bird

community to the FERP gap-harvests from 1995-1998.

Depending on the timing of the initial harvest in a block, a

census of the avian communities in each research area was

done 1 to 3 years before and 1 to 3 years after harvest. No

significant changes in community composition, species

richness, or density were detected, and interestingly, few

pioneer bird species were captured. These responses may

result from the small size of the research areas, or from the

relatively narrow range of the gap sizes created (110 to

2170 m2). Patterns may change greatly after the next gapexpansion harvests in 2005-2008.

ACTIVITIES AND CHALLENGES

Although FERP has increased our understanding of the

Acadian forest over the past 10 years, it faces challenges

common to most young, long-term silvicultural studies. First,

as the study progresses, modifications beyond the original

treatment design may become necessary. For example,

expanding gap systems may run into a “bottleneck” several

cycles out when expansions around existing gaps become

so narrow as to be inoperable and/or residual patches of

trees become susceptible to wind throw. In the 20-10 treatment, this does not become a great issue until the final

cycle (fig. 2a); however, in the 10-30 treatment this will be

a greater problem. Expanding the gaps asymmetrically in

later entries (and thus more closely approximating a group

selection harvest system) may alleviate some of these

concerns.

Sampling design continues to be a challenge. Our inventory system, like many other long-term silvicultural experiments, was originally designed to collect growth and yield

data for the research area as a whole. This approach has

proven inefficient, however, when trying to detect the

influence of harvesting on vegetation dynamics within the

gaps because no more than two of the 20 inventory plots 

in each research area occur within gaps in the 10-30 treatment. Therefore, a system of transects was installed in each

151
expanding gap to alleviate this problem. In addition, spatially explicit questions are becoming more important. For

example, how do gaps and skid trails affect the distribution

of DWD, and the resulting salamander and arthropod habitat, across each research area? We are moving toward more

spatially-explicit sampling designs to help address these

types of questions. For example, the next set of FERP

inventories will use line-transects rather than plot censuses

to inventory DWD and snags across each research area.

Continuity of funding is always a concern. Since 1995,

the FERP operating budget has been reduced and can no

longer support the full suite of measurements that had been

initially collected. Adjustments to the sampling methods

have been incorporated to improve efficiencies and reduce

costs (e.g., changing DWD sampling). However, a periodic

infusion of extramural funding will likely be needed to

maintain the study.

Lastly, continuity of personnel in long-term, universitysponsored research is a persistent challenge. Unlike the

long-term silvicultural experiments conducted by the U.S.

Forest Service at the PEF, which have permanent technical

support, FERP is maintained largely by graduate students.

Fortunately, the Department of Forest Ecosystem Science

has dedicated a graduate research assistantship to FERP. As

a result, three successive Ph.D. students have been able to

coordinate field activities for the program. As the study progresses, however, increasing demands for data management

and field coordination among interdisciplinary research

teams will strain available graduate student time. Time

saving protocols such as using logic checks during data collection, as well as making the database spatially explicit

within a GIS, may help reduce this burden.

CONCLUSION

After 10 years, FERP has completed 10 percent of its

planned lifespan. FERP has been successful thus far

because of consistent support from the College of Natural

Sciences, Forestry, and Agriculture and Department of Forest

Ecosystem Science at the University of Maine. FERP has

created diverse forest conditions in a replicated experiment

that can help interdisciplinary research teams answer pressing questions about the Acadian forest. As FERP approaches

its second decade, however, it enters a period where many

long-term experiments fail. Sometimes this failure results

from a loss in interest in the original research questions as

scarce funding moves to support newer and more exciting

investigations. In other cases, the experiment is unfairly

discredited because not enough time has passed to demonstrate the scientific value of the study. A key lesson learned

in the most successful long-term experiments is that it generally requires a tenacious and persistent researcher to carry

an experiment through these difficult years!

REFERENCES

Brissette, J.C. 1996. Effects of intensity and frequency of 

harvesting on abundance, stocking and composition of

natural regeneration in the Acadian Forest of eastern

North America. Silva Fennica. 30(2-3): 301-314.

Fernandez, I.J. 2004. Personal communication. Professor of 

soil science. Department of Plant, Soil, and Environmental

Sciences, University of Maine, 1 Deering Hall, Orno,

ME 04469.

Fraver, S.; Wagner, R.G.; Day, M. 2002. Dynamics of 

coarse woody debris following gap harvesting in the

Acadian forest of central Maine, U.S.A. Canadian

Journal Forest Research. 32: 2094-2105.

Hartley, M.J. 2003. Effects of small-gap timber harvests 

on songbird community composition and site-fidelity.

Orono, ME: Department of Wildlife Ecology,

University of Maine. 141 p. Ph.D. dissertation.

LI-COR, Inc. 1992. LAI-2000 plant canopy analyzer: 

operating manual. Lincoln, NE: LI-COR, Inc.

Lorimer, C.G. 1977. The presettlement forest and natural 

disturbance cycle of northeastern Maine. Ecology. 

58: 139-148.

Mathis, A. 1990. Territoriality in a terrestrial salamander: 

the influence of resource quality and body size.

Behaviour. 112: 162-175.

Runkle, J.R. 1982. Patterns of disturbance in some oldgrowth mesic forests of eastern North America.

Ecology. 63: 1533-1546.

Saunders, M.R. [N.d.]. Dynamics of down woody debris 

following gap harvesting in the Acadian forest of central Maine, USA: II. Species-specific nutrient contents

and down woody debris nutrient budgets. On file with:

M. Saunders, Department of Forest Ecosystem Sciences,

University of Maine, 5755 Nutting Hall, Orono, ME

04469-5755.

152
Schofield, D.A. 2003. Vegetation dynamics and tree radial 

growth response in harvest gaps, natural gaps, and

closed canopy conditions in Maine’s Acadian forest.

Orono, ME: Department of Forest Ecosystem Sciences,

University of Maine. 146 p. M.S. thesis.

Seymour, R.S. 1992. The red spruce-balsam fir forest of 

Maine: evolution of silviculture practice in response to

stand development patterns and disturbances. In: Kelty,

M.J.; Larson, B.C.; Oliver, C.D. The ecology and silviculture of mixed-species forests. A festschrift for David

M. Smith. Norwell, MA: Kluwer Publishers: 217-244.

Seymour, R.S.; Hunter, M.L., Jr. 1992. New forestry in 

eastern spruce-fir forests: Principles and applications to

Maine. MAFES Misc. Rep. 716. Orono, ME: Maine

Agricultural and Forest Experiment Station, University

of Maine. 36 p.

Strojny, C. 2004. Effects of harvest-created and natural 

canopy gaps on amphibians within a northeastern forest.

Orono, ME: Department of Wildlife Ecology,

University of Maine. 76 p. M.S. thesis.

Thomas, S. [N.d.]. On file with: S. Thomas, Department of 

Biological Studies, University of Maine, 5722 Deering

Hall, Orono, ME 04469-5722.

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1 Emeritus Scientist, Southern Interior Forest Region, BC Forest Service, Kamloops, BC V2C 4E5, Canada. Email for corresponding author:

alan.vyse@gems1.gov.bc.ca

2 Scientist, Pacific Forest Research Centre, Canadian Forest Service, Victoria, BC V8Z 1M5, Canada

3 Scientist, Research Branch, BC Forest Service, Victoria, BC V8W 9C2, Canada

Balancing Ecosystem Values Proceedings, Regional Experiments

Seeking Alternatives to Clearcutting in British Columbia: 

The Role of Large-Scale Experiments for Sustainable Forestry

Alan Vyse,1 Alan K. Mitchell,2 and Louise de Montigny3

INTRODUCTION

In 1990, public forestland management in British

Columbia, which covers an area of about 25 million hectares

(ha), was undergoing severe criticism from environmental

groups and the public. This was primarily because of the

almost universal use of clearcutting to harvest timber. The

criticism focused on the cutting of “big trees” in the temperate rain forest of the southern coast, but echoes of the

controversy were heard throughout the province. Although

the use of clearcutting was vigorously defended by industry

groups, forest professionals, and the government of the day

as the safest and most efficient practice, the need for some

change was also acknowledged. Part of that change was a

government initiative headed by the Ministry of Forests to

examine and develop alternative methods of harvesting for

forest types throughout the province. A substantial body of

research, development, and extension work grew from this

Silvicultural Systems Program (Ministry of Forests 1992).

As part of the program, numerous large-scale, forest manABSTRACT

Numerous large-scale, forest management experiments have been established in British Columbia as part of a government

response to public protests over clearcutting. The experiments test the effect of opening size and concepts such as aggregated

and dispersed retention, on an operational scale with experimental units usually exceeding 10 hectares. Most of the experiments are multidisciplinary in scope and, in some cases, they are interdisciplinary in practice. The short-term outputs from

these experiments have been substantial. A few have led, directly or indirectly, to major shifts in operational practice. The

initial surge of funding has now ended, however, despite these accomplishments. We describe several lessons learned in

British Columbia that might have application in future programs with similar ambitions.

KEYWORDS: Clearcutting, forest management experiments, British Columbia.

155

agement experiments were established around the southern

half of the province, sampling a wide range of ecological

conditions.

In this paper, we provide a brief description of the program and the long-term forest management experiments

that were established under its umbrella. We draw some

conclusions about the success achieved by the experiments,

describe the lessons learned during their establishment, and

speculate on their longevity. 

BRITISH COLUMBIA’S SILVICULTURAL

SYSTEMS PROGRAM 

The Silvicultural Systems Program was initiated in 1990

to investigate alternatives to conventional clearcutting

(defined as clearcutting in large blocks followed by site

preparation and planting to create plantations). Over the 8

years of its life, from 1990 to 1998, about $17 million were

spent on research, development, demonstration, and extension
of alternatives.4 Funding was provided first by the

Provincial Silviculture Program and the Canada-British

Columbia Partnership Agreement on Forest Resource

Development from 1991 to 1995 and then by Forest Renewal

British Columbia. Some of the research projects started

under the program continue to be funded under successor

funding programs.

The declared purpose of the Silvicultural Systems

Program (Ministry of Forests 1992) was to encourage expansion in the range of forest harvesting practices used throughout the province. In 1988-89, 91 percent of the 270 000 ha

harvested on public (crown) land was clearcut. The remaining area was cut using some variety of selection cutting,

mostly by applying diameter limit cuts in the dry Douglasfir (Pseudotsuga menziesii (Mirb.) Franco) stands of the

southern Interior. Although the program did not have an

explicit goal of changing the mix of forest practices within

a specified time frame, the intention of change was clear.

Public brochures and publications showed an idealized

landscape with many forms of silvicultural systems in use

from hilltop to valley bottom. Moreover, the existence of

the program was used to provide the people of the province

and purchasers of wood products from the province evidence of willingness to change (Benskin and Bedford

1994). 

Well over 200 projects were supported over the life of

the program. They ranged from long-term, multidisciplinary forest ecology and management experiments to oneday courses on such topics as even-aged partial cutting for

professional foresters, and brochures describing the range

of silvicultural systems for the general public. In mid-program, when expenditures peaked, about 45 percent of the

funds were spent on long-term research trials, 30 percent

on short-term biological and regeneration issues, 15 percent on issues such as timber pricing impediments to the

implementation of clearcutting alternatives, 5 percent on

extension, and 5 percent on administration. A companion

initiative to the Silvicultural Systems Program was undertaken by the Ministry of Forest’s Small Business Forest

Enterprise Program. Government foresters worked successfully with small business operators over several years to

create examples of silvicultural systems in several coast

and interior parts of the province (Bancroft et al. 1997). 

The program ran with substantial budgets for about 6

years, and severely reduced budgets for 2 more, before

expiring amid a welter of political, institutional, and economic change. The long-term experiments initiated under

the program received continuing funds from new funding

sources for several more years until very recently, when a

number of them have suffered funding cutbacks. 

LARGE-SCALE SILVICULTURAL

SYSTEMS EXPERIMENTS IN BRITISH

COLUMBIA

We have documented 24 large-scale,5 forest management experiments dealing with alternatives to clearcutting

in British Columbia. They can be found throughout the

southern half of the province. Two of the experiments were

established many years ago, one of which was abandoned

and the other recently re-established. Eighteen of the experiments were established in the course of the Silvicultural

Systems Program. One has been established since the program ended. Almost all had, or have, the purpose of demonstrating alternative practices to clearcutting and compare

clearcutting to some silvicultural alternatives. One examines

only uneven-aged management. Several experiments were

designed to examine opening size or overstory retention

levels rather than textbook definitions of silviculture systems. Most consider more than timber values. They are

also generally cooperative, multidisciplinary, and by necessity, interagency projects. The projects are listed in table 1,

and their general location is shown in figure 1. 

Major Accomplishments of the Forest 

Management Experiments

All of the experiments showed that at least some alternatives to clearcutting were operationally feasible. Detailed

cost studies on some projects showed that some alternatives

could be implemented with existing logging machinery

and were not prohibitively expensive (e.g., Mitchell 1996,

Phillips 1995). The experiments also showed that many of

the environmental concerns regarding clearcutting were

either not a concern (e.g., regeneration), or exaggerated

(e.g., soil erosion and nutrient losses), at least in the short

term (Arnott et al. 1995, Huggard and Vyse 2002b). These

results have probably supported a reluctance to move away

from clearcutting throughout the province. In 2002-03,

clearcutting with reserves retained for either riparian protection or wildlife habitat was the dominant logging practice.

(text continues on page 160)

156

4 Information from Ministry of Forests files available from A.Vyse (alan.vyse@gems1.gov.bc.ca)

5 We define large-scale experiments as having treatment units larger than 1 ha.
157

Table 1—Large-scale experiments investigating alternatives to clearcutting in British Columbia

Name of Treatment, size of 

experiment and Ecological zonea treatment units and Ecosystem response

year initiated and location replications variables studied

1. Aleza Lake, SBS Clearcut and shelterwoods Tree growth, vegetation, climate

1930s to 1950s Central Interior with 50% retention; no

Plateau; near replication

Prince George

2. Bolean Lake, MS Clearcut, 50% retention in Tree regeneration, tree growth, bark 

1951 Fly Hills; near stripcuts, group selection, beetles, windthrow

Falkland individual tree selection; Project terminated in early 1970s

5-10 ha.; no replication

3. Quesnel ESSF Clearcut, group selection Climate; soil; tree regeneration; 

Highlands, Quesnel with 1, 0.13, and 0.03 ha tree growth; vegetation; aboreal 

1990 Highlands; near openings; 3 replications lichens; snow 

Williams Lake

4. Uniform SBS 50 and 70% dispersed Climate; tree regeneration; 

Shelterwood, Fraser Plateau; E. retention; shelterwood; windthrow; vegetation, small 

1990 of Williams Lake 1.4 ha; 3 replications mammals

5. Boston Bar, 1991 IDF Clearcut, seed tree, Climate; soil; tree regeneration; 

Fraser Canyon; shelterwood; 2 vegetation; windthrow; logging 

near Boston Bar replications costs

6. Date Creek, 1991 ICH Clearcut, group selection Soil and soil organisms; tree 

N.W. Interior- with 30% removal and regeneration; aboreal lichens; 

Coast transition; 60% removal; 11-38 ha; vegetation; sporocarps, birds, bats, 

near Hazleton 4 replications amphibians, small mammals; 

water; windthrow

7. Lucille Mountain ESSF/ICH Clearcut, shelterwood, Climate; soil; tree regeneration; 

and Northern Cariboo Mountains single tree selection; tree growth; vegetation; aboreal 

Wet belt and Rocky small patch cuts of 0.2 ha; lichens; windthrow

Project, 1991 Mountains; E. of 1-20 ha; no replication; 

Prince George 7 operational trials 

underway or planned in 

Northern Wet belt 

8. MASS, 1991 CWH Clearcut, patch cuts, Climate; soil and soil organisms;

Central Vancouver single tree retention, vegetation; aboreal lichens; tree 

Island; near shelterwood; 5-40 ha; regeneration; birds; canopy 

Campbell River 3 replications arthropods; logging costs

9. Opax Mountain, IDF 80% and 50% retention, Climate; soil and soil organisms; 

1991 Thompson Plateau; aggregated and dispersed; coarse woody debris; tree 

Kamloops openings 0.1, 0.4, and 1.6 ha; regeneration; tree growth; aboreal 

20 ha; 2 replications lichens; ground arthropods; 

vegetation; sporocarps; songbirds; 

woodpeckers; small mammals; 

snow; windthrow
158

Table 1—Large-scale experiments investigating alternatives to clearcutting in British Columbia (continued)

Name of Treatment, size of 

experiment and Ecological zonea treatment units and Ecosystem response

year initiated and location replications variables studied

10. “Beetle proofing” IDF/MS Clearcut and thinned to 4 m Climate, tree regeneration, bark 

mature S. Rocky and 5 m spacing and beetles, windthrow, root disease,

lodgepole pine, Mountain Trench; fertilization; 10-20 ha; vegetation, thermal cover for mule 

1992 near Cranbrook 3 replications deer, logging costs

11. Cats Ears Creek CWH 75% dispersed retention and Tree regeneration; windthrow; 

steep slopes, Central Vancouver aggregated retention with vegetation

1992 Island; near Port 0.15, 0.3 and 1.4 ha 

Alberni openings; 4-7 ha, no 

replication

12. Roberts Creek, CWH 10% dispersed retention; Climate; Soil; timber; wildlife

1992 South Coast; near 50% aggregated retention; except large animals; fungi; 

Sechelt 5-10 ha; no replication water; logging; worker safety costs

13. Sicamous Creek, ESSF 10- and 1-ha clearcuts; array Climate; soil and soil organisms; 

1992 Shuswap of 0.1-ha openings; coarse woody debris; tree 

Highlands, South- single tree selection; regeneration; aboreal lichens; 

Central BC; near all 33% removal; 30 ha; vegetation; sporocarps; ground 

Sicamous 3 replications arthropods; songbirds; 

woodpeckers; spruce grouse; 

small mammals; snow; streams; 

windthrow; bark beetles; logging 

costs

14. West Arm ICH Clearcut; seed tree; Climate; soil; coarse woody debris;

Demonstration Kooenay Lake; shelterwood; patch, single tree regeneration; vegetation; 

Forest, 1992 near Nelson tree and woody debris water quality and quantity

retention; 4500 ha; 

operational trials only; 

no replication

15. Westwold, 1992 IDF 15, 20 and 25 m2 basal area Tree regeneration; tree growth

Okanagan Plateau; retained; 2 Q values;

near Kamloops 1 ha; 3 replications

16. Mount Seven/ ICH Clearcut; low dispersed Climate; soil; coarse woody debris; 

Ice Road, 1993 Columbia retention 30%; high tree regeneration; tree growth; 

Mountains; near dispersed retention 50%; vegetation; root disease

Golden and 1 ha; 4 replications

Nakusp

17. Itcha/Ilgachuz SBPS/MS Clearcut 50% aggregated Climate, soil, tree regeneration; 

Alternative Chilcotin Plateau; retention with stems or tree growth; vegetation, terrestial

Silvicultural W. of Williams whole trees removed, and arboreal lichens, bark beetles, 

Systems, 1994 Lake 70% retention stems only; dwarf mistletoe, sporocarps, 

6-10 ha.; 5 replications; windthrow, wildlife, snow

two additional operational 

trials
159

Table 1—Large-scale experiments investigating alternatives to clearcutting in British Columbia (continued)

Name of Treatment, size of 

experiment and Ecological zonea treatment units and Ecosystem response

year initiated and location replications variables studied

18. Bald Range, MS Regenerated clearcut; 36% Small mammals, vegetation

1995 Okanagan Plateau; retention and uncut;

near Summerland Retrospective study on 

effects of retained 

structures; >10 ha; 

3 replications

19. Fort Nelson BWBS Group shelterwood with .13 Snags and coarse woody debris; 

Mixedwoods, Near Fort Nelson and 1 ha. openings; light; vegetation; 

1996 4 replications tree regeneration

20. Rennell Sound CWH Clearcut, 50 and 70% Tree regeneration; windthrow; 

steep slopes, Graham Island, aggregated retention, 70% vegetation; logging costs

1996 Queen Charlotte dispersed retention; 

Island 5-10 ha; 2 replications

21. Viewland ICH 20% removal; group Mule deer; tree regeneration; 

Mountain, 1996 Quesnel Highlands selection; 0.25-2 ha climate; vegetation; root disease; 

near Williams openings; no replication bark beetles; windthrow; logging 

Lake costs

22. HYP3 –Pattern CWH Diameter limit logging of Soil; tree regeneration; vegetation; 

Process and NW Coast; near low productivity timber; logging costs; water

Productivity in Prince Rupert 50 ha; 2 replications

Hypermaritime 

forests, 1997

23. Mount Tom ESSF Group selection 33% Mountain caribou; arboreal 

Adaptive Quesnel Highlands removed; 0.1-3 ha lichens; tree regeneration; 

Management near Williams openings; >10 ha; windthrow; vegetation; snow; 

Trial, 2000 Lake 9 replications logging costs

24. STEMS – CDF/CWH Clearcut, patch cut, group Climate; tree regeneration; 

Silviculture Central Vancouver selection, aggregate tree growth

Treatments for Island; near retention, dispersed 

Ecosystem Campbell River retention, commercial 

Management in thinning; 3 replications

the Sayward, 

2000

a Ecological zones are described in Meidinger and Pojar 1991. 

BWBS= black and white boreal spruce; CDF= coastal Douglas-fir; CWH= coastal western hemlock; ESSF= Engelmann spruce-subalpine fir;

ICH= interior cedar hemlock; IDF= interior Douglas-fir; MS= montane spruce; SBS= sub-boreal spruce; SBPS= sub-boreal pine spruce.
However, on the lower coast, where social pressures were

most intense, the Montane Alternative Silviculture Systems

(MASS) project led, directly or indirectly, to large-scale

changes in operational practice. There the predominant cutting method changed from clearcutting to variable retention. In the Interior, the Quesnel Highlands and Itcha/Ilgatchuz

Alternaive Silviculture System projects have led to changes

in operational practice to a group selection treatment based

on protecting habitat for the endangered mountain eco-type

of the woodland caribou (Rangifer tarandus caribou).

The more comprehensive trials have shown that all

alternatives have some negative effects on components of

the forest ecosystem. As a consequence, they provide support for the adage “don’t do the same thing everywhere.”

Widespread application of a single practice is unlikely to

be sustainable. These trials have also provided information

on how negative effects could be mitigated. Edge effects

associated with openings were shown to be less intrusive

than previously thought. For example, at Sicamous Creek,

edge effects for many variables were no more than half a

tree height into the forest or into the opening (Huggard and

Vyse 2002a). Windthrow, which is always raised as a major

concern by operational foresters in any discussion of alternatives to clearcutting, was shown to be damaging no matter what system was used, but less damaging than expected

at least in the province interior. In addition much information was gained on the response of tree seedlings to light

environments and to site preparation. And the response of

little-studied elements of the forest ecosystem to forestry

practices, such as small mammals, invertebrates, soil

organisms, lichens and mosses, was recorded. 

160

Figure 1—Location of silvicultural systems trials in British Columbia.
Most of the experiments have been measured at least

once since the treatments were imposed. Some elements,

such as tree seedlings and windthrow, have been measured

several times. And in the case of a few readily assessed

ecological indicators, such as seedfall and songbirds, measurements have been made annually. Although this is a substantial achievement, much more needs to be done. We

expect that some responses will take much longer than a

decade to manifest themselves, and we also expect that

there will be changes in response over time. One example

is the invasion of an experimental site by ants and pocket

gophers that may have been attracted by the disturbance

created by cutting openings. Their interaction with other

established organisms on the site is unknown. 

The scientific output of the program has been substantial. About 80 journal articles have been published to date,

and more appear every year. There are also many more

publications in agency publication series. However the output is very uneven. Three projects account for 90 percent

of the journal articles (Sicamous Creek, Date Creek and

MASS).

Forest researchers are often accused of failing to communicate the results of their work to operational foresters.

However, in the case of the Silvicultural Systems Program,

the possibility of communication failure was dealt with

from the beginning. Researchers were encouraged to discuss

the findings of their work at formal and informal gatherings

of practitioners. Extension notes were produced to apprise

practitioners of the latest findings and who to contact for

more details. Specific courses on silvicultural systems were

designed and delivered through the Forestry Continuing

Studies Network and the Silviculture Institute of British

Columbia. Summary documents were prepared for professional and public audiences alike.

Some Lessons From the British Columbia Experience

The British Columbia experience in establishing numerous large-scale forest management experiments in a short

period offers several lessons for future efforts of this magnitude. We have summarized these lessons as seven rules

for success.

1. Foster strong project leadership and succession.

Projects without effective and committed leadership

will flounder and continuity will be threatened. Good

leaders promote, coordinate, synthesize, integrate,

and plan for all of the research initiatives.

2. Engage operations in research. Project establishment

and continued measurement is expensive, and planning experiments with operational partners is essential. Constant communication with operational

foresters can help maintain interest in the experiment

results, but it does not guarantee continued support. 

3. Plan multidisciplinary and interdisciplinary experiments. Given the pace of societal change, issues of

relevance today may not be the issues of pressing

concern a decade from now. An ecosystem approach

provides a route around such difficulties, and there

can be economies with investigating many ecosystem

responses at once, but the absolute cost is high.

Although there are advantages to imposing a common sampling scheme on an experiment, such a

scheme does not guarantee interdisciplinary work.

The risk of failure may be higher in interdisciplinary

work.

4. Plan your project scale and scope carefully within

your expectations of future resources. Projects at a

single location may have limitations, but the cost of

servicing multiple locations may prove to be an

insurmountable hurdle. 

5. Design robust experiments with strong contrasts.

Remember that biological and statistical significance

are separate concepts. Given that the cost of establishment is high and the pace of institutional change

is rapid, only experiments that have strong contrasts

and highly visible results are likely to have continued

scientific and operational appeal. 

6. Maintaining relevance leads to longevity. Plan for

short-term outputs from long-term projects to keep

your project in the eye of funding agencies and supporters. However, operational relevance can differ

strongly from scientific relevance. This has become 

a problem in British Columbia where funding agencies have required applicants to promise operational

change through research results. Scientists control

neither the rate nor direction of change, and this is

doubly true for forest scientists who must cope with

extremely long periods over which change is measured and assessed. They can contribute knowledge

and elevate the understanding of practitioners, but

these are rarely compelling forces for change. The

increasing demand for scientifically credible forest

management activities, backed by certification, may

help close the gap between operational and scientific

161
relevance, but fundamental differences mean that regular communications between project scientists and

sponsoring forest managers are essential. 

7. Protect your investment. Scientists are sometimes

uncomfortable with promoting their efforts, but promotion of your experiment is essential. Seek a trade

mark for your experiments and publicize your efforts

whenever possible. However, even these efforts may

fail and funding may dry up. Recognize from the outset that specific research funding efforts rarely last 5

years. Build a “sleep mode” into projects so you can

ride out periods of low funding. Make sure you have

data protection and management protocols that

enable the project to be successfully resuscitated 

after hibernation.

CONCLUSIONS

Long-term forest management experiments examining

alternatives to clearcutting in British Columbia have shown,

and communicated clearly, that there are many advantages

to alternatives. They have also demonstrated that the many

supposed negative effects of clearcutting are either exaggerated or without foundation. But they have not provided

any compelling reasons for adopting a wider range of

forestry practice. This may be why these projects are now

stuck in a funding backwater. Their individual contributions

are valued, the need for long-term research is acknowledged, but their upkeep is expensive, and other priorities

beckon. This outcome should not have come as a surprise

to the scientist engaged in the projects. There are numerous

examples of similar projects in British Columbia and elsewhere that have met a similar fate (Smith 1993). 

How do we change this less than encouraging picture?

For those charged with the responsibility of funding forest

research and determining priorities, there has to be acknowledgement that research results and their communication are

not the most important elements leading to change. The

British Columbia experience suggests that success defined

as changing practice or making an economic contribution 

is impossible to predict amid a welter of rapidly changing

social and economic factors and events. Research success,

so defined, has little to do with sound scientific practice or

the communication skills of scientists. If this observation is

generally sound, then the focus of research programs has 

to change. Short-term expectations of individual projects

should be much less important than the long-term expectations, with respect to the whole portfolio of efforts to

improve forestry practice. This is especially true in British

Columbia where the landscape and forest ecosystems are

so varied, and public concerns about the management of

public lands are so volatile. 

For forest scientists, we suggest that working together

to promote the concept of long term funding for long-term

projects might be fruitful. We need to find a way of keeping the forestry community’s feet to the fire. Everyone

acknowledges the need for a long time horizon in forestry

and the need for long-term research, but no one seems willing to pay despite the low cost. Even at its funding peak,

the annual cost of the Silvicultural Systems Program was

less than 1 percent of the stumpage value of logs removed

from public lands. In British Columbia we have been developing the concept of Living Forest Laboratories, supported

by an endowment or endowments. We propose to promote

the concept of long-term forest experiments to the funding

agencies and the public using the familiar idea of scientific

laboratories (de Montigny et al. 2004). If the public is willing to support building very expensive laboratories for

cancer research, perhaps they might also be willing to support much lower cost living forest laboratories for forest

management research. 

ACKNOWLEDGMENTS

We thank our colleagues, in particular Dave Huggard,

Doug Maynard, and Gary Hogan, for fruitful discussions

on this topic. And we thank our fellow large-scale experimenters for supplying the information on the British

Columbia projects.

REFERENCES

Arnott, J.T.; Beese, W.J.; Mitchell, A.K.; Peterson, J., eds. 

1995. Proceedings Montane Alternative Silviculture

Systems (MASS) Workshop. FRDA Report 238.

Victoria, BC: Ministry of Forests. 122 p.

Bancroft, B.; Zielke, K.; Deverney, S. 1997. Evaluation of 

alternative silviculture systems within the special log

sales projects for the small business program. Victoria,

BC: Ministry of Forests, Forest Practices Branch. 28 p.

Benskin, H.; Bedford, L. 1994. Multiple purpose silviculture in British Columbia. Forestry Chronicle. 

70: 252-259.

De Montigny, L.; Larson, B.; Mitchell, A.K.; Vyse, A. 

2004. Meeting the need for cost-effective, long-term

forest ecosystem management experiments in British

Columbia. Victoria, BC: Ministry of Forests, Research

Branch. 11 p.

162
Huggard, D.J.; Vyse, A. 2002a. Edge effects in high elevation forests at the Sicamous Creek Project. Extension

Note 62. Victoria, BC: Ministry of Forests, Research

Program. 6 p.

Huggard, D.J.; Vyse, A. 2002b. Comparing clearcutting and 

alternatives in a high elevation forest: early results from

the Sicamous Creek Project. Extension Note 63. Victoria,

BC: Ministry of Forests, Research Program, 8 p.

Meidinger, D; Pojar J., eds. 1991. Ecosystems of British 

Columbia. Special Report Series 6. Victoria, BC:

Ministry of Forests. 329 p.

Ministry of Forests. 1992. Alternatives to clearcutting: a 

strategy for finding solutions. Victoria, BC: Ministry 

of Forests, Silviculture Branch. 7 p.

Mitchell, J.L. 1996. Trial of alternative silvicultural 

systems in southern British Columbia: summary of harvesting operations. Technical Note TN-240. Vancouver,

BC: Forest Engineering Research Institute of Canada.

11 p.

Phillips, E. 1995. Harvesting logistics and costs. In: Arnott, 

J.T.; Beese, W.J.; Mitchell, A.K.; Peterson, J., eds.

Proceedings Montane Alternative Silviculture Systems

(MASS) workshop. FRDA Report 238 9-13. Victoria,

BC: British Columbia Ministry of Forests. 

Smith, D.M. 1993. Silvicultural Systems Program: British 

Columbia Ministry of Forests. Discussion paper. Victoria,

BC: Ministry of Forests, Silviculture Branch. 28 p.

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1 Assistant Professor of silviculture, Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA. Email for 

corresponding author: ezenner@umn.edu

2 Research Forester, USDA Forest Service, North Central Research Station, Columbia, MO 65211, USA

3 Botanist, Ashland, MO 65010, USA

4 Resource Staff Scientist, Missouri Department of Conservation, Ellington, MO 63638, USA

Balancing Ecosystem Values Proceedings, Regional Experiments

Are Landscape-Level Effects More than the Sum of Stand-Level 

Effects in the Missouri Ozark Forest Ecosystem Project?

Eric K. Zenner,1 John M. Kabrick,2 Jennifer K. Grabner,3 and Randy G. Jensen4

INTRODUCTION

Management objectives for Missouri’s public and private

forests are very complex and include the maintenance of

ecosystem processes, conservation and restoration of habitat

for Neotropical migrant songbird, small mammal, and herpetofaunal communities, creation of forests with old-growth

attributes, and extraction of commodities (Missouri

Department of Conservation 1986). Management decisions

to integrate these complex objectives are often based on

local or stand-scale habitat characteristics (Chen et al. 2002).

Traditional silvicultural, stand-level research and withinpatch explanations may be inadequate for many ecological

ABSTRACT

The Missouri Ozark Forest Ecosystem Project (MOFEP) is a large-scale, long-term experiment that tests the effects of

even-aged management (EAM), uneven-aged management (UAM), and no-harvest management (NHM, control) on upland

forest components. We evaluated pre- (1994, 1995) and post-treatment (1999, 2000) changes for ground flora species richness, percentage of ground cover, and relative cover of seven life-form groups collected from 645 permanent plots. Analyses

were conducted at two levels: (1) following the experimental model using landscape-level data in an analysis of variance design,

and (2) using stand-level data to determine if changes in treated sites were confined to harvested plots only. Significant

landscape-level treatment effects were observed for species richness and the relative cover of annual/biennial species, woody

vines, and legumes. Mean species richness per plot decreased significantly in NHM sites and increased slightly in both EAM

and UAM sites. The relative cover of annual/biennial species and woody vines increased in all sites; in all cases, more so

for harvested sites than NHM sites. The relative cover of legumes decreased in harvested sites, and increased slightly in NHM

sites. At the stand-level, no differences were observed for any response variable between NHM sites and uncut plots on

harvested sites. In plots directly impacted by timber harvests, species richness increased, cover increased dramatically, relative cover of annuals/biennials, graminoids, and woody vines increased, and relative cover of legumes decreased. The magnitude of these changes was strongly related to the created gradient in canopy openings. Almost all life-forms exhibited

significant differences in relative cover between clearcut and NHM plots.

KEYWORDS: Even-aged, ground flora, Missouri Ozark Forest Ecosystem Project (MOFEP), silviculture, uneven-aged. 

165

phenomena, however, where broad-scale landscape perspectives are needed (Franklin 1993).

The Missouri Ozark Forest Ecosystem Project (MOFEP)

is a multidisciplinary, long-term, landscape-scale experiment

replicated and monitored through time to determine causeand-effect relationships among management alternatives on

multiple forest ecosystem components and to detect how

the profile of these effects changes over time (Sheriff and

He 1997, Walters 1993). Specifically, MOFEP tests effects

of even-aged (EAM), uneven-aged (UAM), and no-harvest

(NHM) management practices on the flora and fauna of

upland oak ecosystems (Brookshire et al. 1997). MOFEP
consists of nine sites (landscapes) that range from 312 ha

to 514 ha and contain between 41 and 71 stands each and

is thus suited to address landscape-level questions.

There is growing concern that timber harvesting may

have deleterious effects on the long-term maintenance of

species diversity and composition (Burton et al. 1992).

Because the ground flora represents the majority of plant

species in many forest communities (Thomas et al. 1999),

any evaluation of different silvicultural treatments must

consider changes to the species composition of the ground

layer vegetation (Jenkins and Parker 1999). How and to

what extent a gradient of harvest intensities and canopy

openings alters the ground flora structure and composition

is uncertain. Although MOFEP is designed to test hypotheses

primarily at the landscape-level, evaluating treatment

responses at finer scales may give better insights into the

processes that are ultimately responsible for the observed

effects. In this paper, we tested the hypothesis that different

silvicultural treatments can rapidly induce changes in species

richness, cover of ground-layer vegetation, and relative

cover of several ground flora life-form groups (e.g., forbs,

graminoids, shrubs, etc.) in upland oak communities in the

Missouri Ozarks. We report on the short-term changes of

the ground-layer vegetation at both stand- and landscapelevels in response to the first round of timber harvesting. 

METHODS

Study Area

The study sites in the Current River Hills Subsection 

of the Ozark Highlands are located in Carter, Reynolds and

Shannon counties of southeastern Missouri (lat 37°00' to

37°12'N and long 91°01' to 91°13'W). The area is characterized by a humid, continental climate, with hot, humid

summers and cool winters. Mean annual temperature is

13.3°C. Average annual precipitation is 112 cm with most

rain falling in spring and summer (Chen et al. 2000). Sites

have primarily mature, second-growth oak-hickory and oak

pine forests with relatively closed canopies. Common overstory trees include black oak (Quercus velutina Lam.),

white oak (Quercus alba L.), scarlet oak (Quercus coccinea

Muenchh.), post oak (Quercus stellata Wang.), shortleaf

pine (Pinus echinata P. Mill.), black hickory (Carya texana

Buckl.), mockernut hickory (Carya tomentosa Mill.), and

pignut hickory (Carya glabra Mill.). Flowering dogwood

(Cornus florida L.), blackgum (Nyssa sylvatica Marsh.),

and sassafras (Sassafras albidum Nutt.) are common understory trees and shrub species. Most overstory trees on the

sites range from 50 to 70 years old; trees older than 100

years occur on all sites, and a few trees are older than 140

years. 

Experimental Layout and Silvicultural Treatments

The nine MOFEP sites form a randomized complete

block design with three replicates of three silvicultural systems (even-aged management (EAM), uneven-aged management (UAM), and no-harvest management (NHM, see

Sheriff and He 1997). Stands located in EAM sites are subject to no-cutting treatment, thinning treatment, or the clearcut with reserves harvest treatment. About 10 percent of

the acreage in a site is or will be clearcut every 10 to 15

years for forest regeneration, and thinnings are implemented

to improve tree quality and growing space of residual trees

(Kabrick et al. 2002). Cutting rotations are about 100 years,

with 10 percent of each site left to develop toward oldgrowth, reserved from harvest. Stands in the UAM sites are

subject to no-cutting treatment, the single tree selection

harvest treatment, or the group selection harvest treatment.

A combination of single tree and group selection is implemented to improve stand quality, regulate tree size distribution (single tree selection), and create canopy gaps large

enough to regenerate shade-intolerant or intermediatelytolerant tree species such as most oaks and shortleaf pine

(group selection). Group openings are 21 m on south-facing

slopes to 43 m in diameter on north-facing slopes (Law and

Lorimer 1989). Negative exponential diameter distributions

defined with the residual basal area (i.e., B-level stocking

after Roach and Gingrich (1968)), the largest tree diameter

(i.e., desired sawtimber size objective for an identical EAM

site), and q-factor (i.e., about 1.5 for trees >11 cm d.b.h.)

were used to control stocking. The diameter distribution for

large trees of UAM is thus identical to the composite size

class distribution across the EAM sites. Approximately 10

percent of each site is designated as old-growth reserve.

The total area of group openings was to be approximately 

5 percent of the harvested area in UAM sites. Vegetation

plots in the NHM sites do not receive timber harvesting,

serving as control replicates for the experiment and providing information on changes due to natural disturbances in

upland Ozark forests in the absence of active management

(for more detail on the prescriptions, see Brookshire et al.

1997). 

Field Inventory

A total of 645, 0.2 ha permanent vegetation plots (70 to

74 plots per site, at least one per stand) were monitored for

changes in vegetation following harvest treatments. Within

each of the permanent plots, 16 one-meter square subplots

were established in which all herbaceous and woody plants

<1 m tall were identified to species and assigned estimates

of percent live foliar coverage. Nomenclature follows that

of Steyermark (1963). 

166
Pretreatment data were collected during the summers of

1994 and 1995. Timber harvest treatments were applied in

1996. A total of 455 plots received no harvest treatment, 79

received single-tree selection, 33 were thinned, 45 received

group-openings, and 22 were clearcut. Post-treatment data

were collected in the summers (June through August) of

1999 and 2000. Sites were sampled in the same order and

during the same 2- to 3-week period each year to avoid

potentially confounding seasonal effects. 

Calculations and Plant Groups

Plot-level species richness was the total number of

species identified in each 0.2 ha plot. The mean percentage

of ground cover at the plot level was total cover averaged

across the 16 subplots in each plot. Each species was

assigned to one of seven life-form groups: (1) annual and

biennial species, (2) nonleguminous forbs, herbaceous vines,

and ferns, (3) graminoids (grasses, sedges, and rushes), (4)

legumes, (5) woody vines, (6) shrubs, and (7) trees. Relative

cover was calculated for each species and for life-form

groups as the ratio (*100) of the sum of coverage for each

species or life-form group on each subplot divided by the

total sum of all species coverages on that subplot. Pretreatment means were calculated as the average of 1994 and

1995 values, and post-treatments means were calculated as

the average of 1999 and 2000 values. For a list of ground

flora species frequency and abundance see Grabner (2000a).

Data Analysis

Analysis of variance (ANOVA) was used to test for

block and silvicultural treatment effects among sites (landscape-level analyses) on changes (post- minus pretreatment

values) of mean ground flora species richness, mean percent cover, and mean relative cover of life-form groups.

Because there were at least marginally significant pretreatment differences in plot species richness (p = 0.06), cover

(p = 0.05), relative cover of graminoids (p = 0.03) and

woody vines (p = 0.05) among NHM, UAM, and EAM

sites, pretreatment levels were used as covariates when

analyzing changes due to the treatments. Tukey’s HSD

multiple-comparisons tests were used to investigate differences among treatments. ANOVA and Tukey’s HSD multiple comparisons tests were also used to test the hypothesis

that vegetation changes were proportional to harvest intensity (e.g., clearcut, thinning, group selection, single tree

selection, and uncut plots). For these stand-level analyses,

all plots in NHM sites were combined with uncut plots of

EAM and UAM sites into one treatment type (uncut) after

no statistically significant differences (all p-values > 0.05)

were found for changes in ground-layer vegetation of any

response variable among these plots. Plots within sites are

not statistically independent and error estimates can thus be

misleading; extrapolation of these results beyond the study

sites is subsequently not warranted. 

RESULTS

Treatment Effects Between Sites 

(Landscape-Level Analyses)

Ground flora across sites was diverse (gamma diversity

>530 vascular species), but only a few woody vines, understory trees, and legumes (e.g., Tick trefoil (Desmodium

nudiflorum L.), flowering dogwood, sassafras, Virginia

creeper (Parthenocissus quinquefolia L.), summer grape

(Vitis aestivalis Michx.), black oak, and hog peanut

(Amphericarpa bracteata L.)) were predominant by relative cover and frequency at all sites. More than 60 percent

occurred in fewer than 10 percent of all plots each year.

For details, see Grabner (2000b).

Significant treatment effects were detected for species

richness (p < 0.01). Species richness decreased by 3.0

species in NHM sites, while increasing by 2.8 and 2.5

species in EAM and UAM, respectively. Cover in treated 

sites (EAM sites 6.1 percent, UAM sites 6.6 percent)

increased slightly compared to the NHM sites (2.7 percent),

but not by a statistically significant amount (p = 0.20).

At least marginally significant treatment effects were also

observed for relative cover of annuals/biennials (p = 0.06),

woody vines (p = 0.04), and legumes (p < 0.01). The greatest increases in relative cover of annuals/biennials and woody

vines were observed in EAM sites. Relative cover of legumes

decreased in EAM and UAM sites, but increased slightly in

NHM sites. No significant treatment effects were observed

for relative cover of non-leguminous forbs (p = 0.26), graminoids (p = 0.15), shrubs (p = 0.17), and small tree

seedlings (p = 0.17). 

Treatment Effects Within Sites (Stand-Level Analyses)

Species richness and cover increased significantly (both

p < 0.001) following harvest along a gradient of harvest

intensity; the greatest responses occurred in clearcuts, while

uncut stands showed relatively little change (fig. 1). Clearcut

plots were significantly different from thinned EAM plots,

plots with group selection and single-tree selection, as well

as from uncut plots. UAM plots responded intermediately

between clearcut and uncut plots, but similarly to thinned

plots. Species richness in group selection plots increased

significantly more than in single-tree selection plots.

With the exception of shrubs, clearcut plots were significantly different from uncut plots (all p < 0.05, fig. 1).

Compared to uncut plots, clearcut plots showed increases

167
168

Figure 1—Mean differences between post- and pretreatment values along a harvest intensity gradient. UAM_Sel refers to single-tree selection 

plots, UAM_Group refers to group selection plots, EAM_Thin refers to thinned plots, EAM_CC refers to plots that were clearcut. Differing 

letters indicate statistically significant differences among harvest treatments based on Tukey’s HSD multiple comparisons test (α = 0.05). 
in relative cover of annuals/biennials, forbs, graminoids,

and woody vines; clearcuts showed decreases in relative

cover of legumes and tree seedlings. Thinned plots generally

responded intermediately between clearcut and uncut plots.

Only relative cover of legumes and woody vines showed

significant differences between thinned and uncut plots.

Changes in relative cover of forbs, graminoids, legumes,

and tree seedlings were significantly different between

thinned and clearcut plots. Only relative cover of legumes

differed significantly between single-tree selection plots and

uncut plots. Responses were not different between plots with

single-tree selection and group selection, although changes

in relative cover of legumes and woody vines were significantly more pronounced in plots with group selection

compared to uncut plots.

DISCUSSION

Responses to different silvicultural treatments of all

ground-layer species combined, and by life-form, were

extremely variable. Whereas harvesting induced significant

changes in species richness and relative cover of annuals/

biennials, forbs, legumes, and woody vines, responses of

ground cover and relative covers of shrubs and trees were

less straightforward, and no clear relationships to the harvesting gradient emerged at the landscape-level. There are

two primary reasons for this outcome. First, no evidence

was found that changes due to the harvesting occurred 

anywhere except in cut plots, and responses in uncut plots

within EAM and UAM sites were very similar to those

observed in NHM sites (natural background change). Second,

with the exception of annuals/biennials, legumes, and

woody vines, changes induced by harvesting only a small

portion of stands within EAM and UAM sites were too

small to result in significant landscape-level changes. This

is not to say, however, that harvesting did not result in standlevel changes of relative cover for other life-forms as well.

In fact, in most cases the cover of different life-forms

changed significantly when clearcut plots were compared

to uncut plots.

Responses at the landscape-level largely reflected the

magnitude of change induced in the actually treated plots.

Stand-level vegetation responses in plots subjected to harvesting often paralleled the gradient of canopy openings

induced by different harvesting intensities. For example,

species richness tended to increase slightly (though not 

significantly) in thinned (EAM) and single-tree selection

(UAM) plots, and significantly in group opening (UAM)

and clearcut (EAM) plots. All harvested plots tended to

also increase substantially in mean percentage of total

ground cover, with woody vine species such as summer

grape (Vitis aestivalis) and early successional shrubs such

as blackberry (Rubus pensilvanicus) contributing in large

part to this increase. Annual and biennial species such as

fireweed (Erechtites hieracifolia), daisy fleabanes (Erigeron

spp.), and cudweed (Gnaphalium spp.), which were essentially absent prior to treatment implementation, exhibited a

moderate increase in relative cover in cut plots. Woody

vines such as summer grape and Virginia creeper increased

in relative cover across most plots, but most noticeably in

harvested plots and particularly in clearcuts and plots with

group openings. Legumes decreased significantly in relative

cover in all harvested plots, while remaining unchanged in

most uncut plots. This decrease was primarily due to marked

declines in the cover of two very abundant closed-canopy

forest species, tick trefoil and hog peanut, which typically

occurred in 85 to 95 percent of all pretreatment plots and

were always among the top ten species in terms of mean

relative pretreatment cover (Grabner et al. 1997). Though

not large enough to translate into significant landscape-level

changes, mean cover by graminoids such as panic grass

(Panicum boscii), nut rush (Scleria triglomerata), and blackedged sedge (Carex nigromarginata) increased in all plots,

and particularly in clearcuts and plots with group openings.

Results from this study indicate that different harvesting

intensities implemented at the stand-level can result in

statistically significant landscape-level changes of the groundlayer vegetation, provided the observed changes are substantial. Statistical significance of treatment effects at the

landscape-level can be observed even though treatment

effects were spatially confined to the actually treated areas.

For example, post- and pretreatment differences between

10 and 30 percent for species richness within even-aged

sites were large enough to translate into statistically significant differences at the landscape-level. Are the results of

this study, therefore, suggestive of a landscape-level effect,

reflecting processes that occurred at larger, landscape-level

scales?

After the first round of harvesting, there is no evidence

that landscape-level changes in the ground-layer vegetation

are more than the sum of stand-level effects. Although dramatic differences were observed at the stand scale along a

gradient of no harvest, thinned, single tree, group selection,

and clearcut plots, there are no obvious signs that groundlayer vegetation responses were driven by processes that

occurred at the landscape-level. That is not to say, however,

that landscape-level responses will necessarily continue to

be merely scaled-up, (linearly extrapolated) stand-level

responses. Our understanding of what controls the rate and

direction of vegetation change across spatial scales is currently too incomplete to predict whether or not changes in

169
the composition of the understory will continue to be more

or less proportional to the treated area, or if is there a point

where those changes become nonlinear. We also do not

know if there is a critical level of fragmentation where, due

to the combination of habitat loss, invasive species, and

dispersal limitation, the recovery and diversity of the groundlayer flora may be compromised. Note that a linear change

of the ground flora following harvesting may result in nonlinear changes of some fauna and thereby result in landscape-level effects beyond those that may be expected from

simple stand-level extrapolation. We contend that future

research efforts should be directed at developing predictive

modeling approaches that scale stand-level results up to the

landscape level. Creative, new statistical designs may be

needed to directly address scaling issues and process research

within the framework of large-scale studies. Within MOFEP,

field observations and experimental analyses must now be

combined with the concepts of patch dynamics and hierarchy

theory to develop a coherent, spatially explicit, across-scale

understanding of forest dynamics that enables the development of scientifically sound management and conservation

plans. 

ACKNOWLEDGMENTS

We thank the many technicians who collected and entered

these data, as well as the many individuals who provided

assistance with training and taxonomy. We thank Steve

Sheriff for helpful comments and discussions regarding the

MOFEP experimental design. The MOFEP ground flora

study was funded by the Forestry Division of the Missouri

Department of Conservation.

REFERENCES

Brookshire, B.L.; Jensen, R.G.; Dey, D.C. 1997. The 

Missouri Ozark Forest Ecosystem Project: past, present,

and future. In: Brookshire, B.L.; Shifley, S.R., eds.

Proceedings of the Missouri Ozark Forest Ecosystem

Project symposium: an experimental approach to landscape research. Gen. Tech. Rep. NC-193. St. Paul, MN:

U.S. Department of Agriculture, Forest Service, North

Central Forest Experiment Station: 1-25.

Burton, P.J.; Balisky, A.C.; Coward, L.P.; Cumming, S.G.; 

Kneeshaw, D.D. 1992. The value of managing for biodiversity. Forestry Chronicle. 68: 225-237.

Chen, J; Huebner, C.D.; Saunders, S.C.; Song, B. 2002. 

Plant distribution and diversity across an Ozark landscape. In: Kabrick, J.M.; Shifley, S.R., eds. Proceedings

of the 27th Annual Natural Areas Association conference:

post-treatment results from the Missouri Ozark Forest

Ecosystem Project. Gen. Tech. Rep. NC-227; St. Paul,

MN: U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station: 45-65.

Franklin, J.F. 1993. Preserving biodiversity: Species, 

ecosystems or landscapes? Ecological applications. 

3: 202-205.

Grabner, J.K. 2000a. Appendix D. MOFEP ground flora 

species frequency, abundance, and field notes. In:

Shifley, S.R.; Brookshire, B.L., eds. Missouri Ozark

Forest Ecosystem Project: site history, soils, landforms,

woody and herbaceous vegetation, down wood, and

inventory methods for the landscape experiment. Gen.

Tech. Rep. NC-208. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest

Experiment Station: 305-314.

Grabner, J.K. 2000b. Ground layer vegetation in the 

Missouri Ozark Forest Ecosystem Project: pretreatment

species composition, richness, and diversity. In: Shifley,

S.R.; Brookshire, B.L., eds. Missouri Ozark Forest

Ecosystem Project: site history, soils, landforms, woody

and herbaceous vegetation, down wood, and inventory

methods for the landscape experiment. Gen. Tech. Rep.

NC-208. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment

Station: 107-123.

Grabner, J.K.; Larsen, D.R.; Kabrick, J.M. 1997. An analysis of MOFEP ground flora: pretreatment conditions. In:

Brookshire, B.L.; Shifley, S.R., eds. Proceedings of the

Missouri Ozark Forest Ecosystem Project symposium:

an experimental approach to landscape research. Gen.

Tech. Rep. NC-193. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest

Experiment Station: 169-197.

Jenkins, M.A.; Parker, G.R. 1999. Composition and diversity of ground-layer vegetation in silvicultural openings

of southern Indiana forests. The American Midland

Naturalist. 142: 1-16.

170
Kabrick, J.M.; Jensen, R.G.; Shifley, S.R.; Larsen, D.R. 

2002. Woody vegetation dynamics following even-aged

and uneven-aged harvest treatments on the Missouri

Ozark Forest Ecosystem Project (MOFEP). In: Kabrick,

J.M.; Shifley, S.R., eds. Proceedings of the 27th Annual

Natural Areas Association conference: post-treatment

results from the Missouri Ozark Forest Ecosystem

Project. Gen. Tech. Rep. NC-227; St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North

Central Forest Experiment Station: 84-101.

Law, J.R.; Lorimer, C.C. 1989. Managing uneven-aged 

stands. In: Clark, F.B.; Hutchinson, J.G., eds. Central

Hardwood Notes. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North-Central Forest

Experiment Station: 6.08: 1-6.

Missouri Department of Conservation. 1986. Forest 

Management Guidelines. Missouri Department of

Conservation. 81 p.

Roach, B.A.; Gingrich, S.F. 1968. Even-aged silviculture 

for upland central hardwoods. Agric. Handb. 355. Washington, DC: U.S. Department of Agriculture,

Forest Service. 39 p.

Sheriff, S.L.; He, Z. 1997. The experimental design of 

the Missouri Ozark Forest Ecosystem Project. In:

Brookshire, B.L.; Shifley, S.R., eds. Proceedings of the

Missouri Ozark Forest Ecosystem Project symposium:

an experimental approach to landscape research. Gen. Tech. Rep. NC-193. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest

Experiment Station: 26-40.

Steyermark, J.A. 1963. Flora of Missouri. Ames, IA: Iowa 

State University Press. 1,728 p.

Thomas, S.C.; Halpern, C.B.; Falk, D.A.; Liguori, D.A.; 

Austin, K.A. 1999. Plant diversity in managed forests:

understory responses to thinning and fertilization.

Ecological Applications. 9: 864-879.

Walters, C.J. 1993. Dynamic models and large scale field 

experiments in environmental impact assessment and

management. Australian Journal of Ecology. 18: 53-61.

171
Stand structure in Washington State Capitol Forest 75 years after railroad logging. Photo by Tom Iraci

continue
MODELING AND SIMULATION
This page was intentionally left blank.
1 Research Leader, Stand Development Modelling Group, MOF Research Branch, P.O. Box 9519 Stn. Prov. Govt., Victoria, BC V8W 9C2, Canada. 

Email for corresponding author: jim.goudie@gems4.gov.bc.ca

2 Growth and Yield Applications Specialist, Stand Development Modelling Group, MOF Research Branch, P.O. Box 9519 Stn. Prov. Govt., Victoria, 

BC V8W 9C2, Canada

3 Wildlife Habitat Ecologist, MOF Southern Interior Forest Region, 515 Columbia St., Kamloops, BC V2C 2T7, Canada

4 Consultant, 1481 Chinook Place, Kamloops, BC V2E 1A4, Canada

5 Research Scientist, Ecological Processes, Silviculture Systems and Forest Dynamics, MOF Research Branch, P.O. Box 9519 Stn. Prov. Govt., Victoria, 

BC V8W 9C2, Canada

6 Stand Modelling Analyst, Stand Development Modelling Group, MOF Research Branch, P.O. Box 9519 Stn. Prov. Govt., Victoria, BC V8W 9C2, Canada

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Application of Simulation Models to the Design 

and Analysis of Silvicultural Systems in British Columbia

James W. Goudie,1 C. Mario Di Lucca,2 Walt Klenner,3

Ian R. Cameron,4 Roberta Parish,5 Kenneth R. Polsson6

INTRODUCTION

British Columbia (BC) is a large, geographically diverse

province in western Canada that occupies about 950 000

km2 of land. It is almost as large as California, Oregon,

Washington, and Idaho combined. It has over 26 million ha

of productive forest land that is categorized into 14 biogeoclimatic ecosystem classification (BEC) zones (Pojar et al.

1987). Substantial north-south mountain ranges intercept

ABSTRACT

The Ministry of Forests in British Columbia supports the development of three stand-level simulation models—the 

Tree and Stand Simulator (TASS) (Mitchell 1975a, Mitchell and Cameron 1985), PrognosisBC (Zumrawi et al. 2002), and

SORTIE/BC (Coates et al. 2003). Each model has unique characteristics, capabilities, and applications to ensure accurate

projections of the diverse forest conditions in British Columbia. This paper focuses on TASS, which supports traditional 

silvicultural decisions and timber supply analysis. It is also used to design, project, and evaluate nontraditional silvicultural

systems and stand management strategies. TASS also is used to simulate variable retention systems, a need arising from 

recommendations of the Clayoquot Scientific Panel (1995) that harvesting systems be based on an ecosystem management

approach. MacMillan Bloedel Ltd. (now Weyerhaeuser) was the first company to adopt an approach that eliminated clearcutting in coastal forests in favor of retaining components of the preceding forest on every cut block. Previously, trials

addressing alternative silvicultural systems were primarily implemented by research staff, but often with unknown growth

and yield consequences. Computer models are effective tools that can provide useful information to help develop policy 

and design innovative field experiments.

This paper briefly reviews progress to date, available applications, and needs for further model development and 

application. 

KEYWORDS: Simulation, modeling, variable retention, growth and yield.

175

moisture and produce annual rainfall that varies from over

300 cm on the extreme west coast to under 40 cm in the

desert-like conditions of the Fraser River Canyon. The

forests differ accordingly—lush, temperate cedar-hemlock

rain forests on the coast; dry, low elevation Ponderosa pine

(Pinus ponderosa P. & C. Lawson) forests in the southern

interior; and cold, high elevation Engelmann spruce (Picea

engelmannii Parry ex Engelm.)—subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forests in the Rocky Mountains. The
176

Ministry of Forests supports the development of three simulation models to project the dynamics of forests growing

under these diverse forest conditions. The goal is to produce models that are

• Accurate - predict the future state of the forests with

acceptable accuracy;

• Applicable - cover a diversity of sites, species and

stand structures;

• Adaptable - expandable to address emerging practices

and issues;

• Accepted - conform with known information, and

inspire confidence;

• Affordable - relatively inexpensive to develop, 

maintain and support; and

• Available - distributed freely and supported rigorously.

Two of the models, PrognosisBC and SORTIE/BC, were

parameterized for and otherwise adapted to British Columbia

conditions over the last 5 to 10 years. PrognosisBC (Zumrawi

et al. 2002) is a variant of the Forest Vegetation Simulator

originally developed in the intermountain Pacific Northwest

(Stage 1973, Wykoff et al. 1982). It is a non-spatial, tree

list model that projects existing stands in the southeastern

region of the province. SORTIE is a spatially explicit model

that was originally developed to estimate successional

sequences in deciduous forest conditions in eastern United

States using predicted light conditions (Canham 1988,

Pacala et al. 1993). SORTIE/BC was parameterized to estimate understory succession patterns for partial cutting

regimes in interior cedar-hemlock (ICH) forests in northern British Columbia (Coates et al. 2003). SORTIE has

also been adapted to other regions across Canada.

The Tree and Stand Simulator (TASS) (Mitchell 1975a,

1975b) has produced yield tables for second-growth managed forests for over 20 years (e.g., Mitchell and Cameron

1985). These tables are now electronically distributed via

the Table Interpolation Program for Stand Yield (TIPSY)

(Mitchell et al. 2000). TASS can estimate the effects of

intensive silvicultural treatments on financial return (e.g.

Mitchell 1995) and the effects of stand tending on the habitat requirements of several wildlife species (Greenough et

al. 1996). Application of the model to nontraditional harvesting strategies has increased rapidly since recommendations

of the Clayoquot Scientific Panel (1995) were accepted.

MacMillan Bloedel Ltd. (now Weyerhaeuser) was the first

company to eliminate traditional clearcutting from coastal

forest land (private and licensed). Other companies have

since adopted similar strategies. Over a dozen field installations established in British Columbia since 1990 examine

alternatives to clearcutting because there is little knowledge

about the probable effects. This paper discusses some ongoing

applications of TASS that assist the development of nontimber management strategies and the design of silvicultural

systems trials.

MODEL DESCRIPTION AND HISTORY

Mitchell (1969) conceived and coded the original TASS

I in the mid-1960s for managed stands of interior white

spruce (Picea glauca (Moench) Voss). Simulated trees were

positioned on a flat, 1-foot grid and crowns competed for

growing space in a two-dimensional environment. A major

reconfiguration, TASS II, occurred in the late1960s when

the focus shifted to coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) (Mitchell 1975a, 1975b). Tree crowns

are represented by concentric smooth shells (fig. 1) that

compete in three-dimensional computer space. Dominant

height growth is the key driver, and every tree is assigned a

height growth that ranges from about 50 to 120 percent of

site trees. Each tree is also assigned a rate of crown expansion relative to height growth (see equation 2, in Mitchell

1975a). Crowns compete for three-dimensional space, and

vigorous trees eventually overtop weaker neighbors. Competitive mortality occurs when trees are overtopped by a

critical distance—a surrogate for light attenuation (fig. 2).

Annual bole increment is primarily a function of the amount

of volume the crown shells occupy, a proxy for foliar biomass (equation 19, in Mitchell 1975a). TASS II is calibrated

to a large database of 15,000 permanent sample plots and

validates against independent thinning experiments (Goudie

1998). Available silvicultural treatments in the system

include initial density, spatial distribution, thinning, pruning, fertilization and genetic improvement. 

Like most early computer models, TASS II was originally coded in Fortran IV and executed on large mainframe

computers. Visualization of the simulations has always

been an important element because our experience shows

that realistic graphic representations

• Facilitate model verification and de-bugging;

• Improve communications between modelers, audiences

and colleagues (e.g., scientists, managers, students, 

general public);

• Generate confidence among clients (e.g., scientists, 

practitioners, managers, politicians); and

• Improve the success of research grant proposals.
Graphic visualizations have improved considerably over

the years (fig. 3). Before 1988, paper maps were printed

from the internal program grid and crown perimeters were

laboriously hand drawn to examine model behavior and

demonstrate the competitive dynamics (fig. 3a). Algorithms

were created to use 16-color EGA capabilities (fig. 3b) after

TASS was converted to an appropriate computer language

(C) that facilitates graphical representations and transported

to a microcomputer environment in 1988. Images were

drawn directly to the screen and captured to verify and

illustrate the system. By 1990, 256-color VGA accommodated more realistic portrayal of tree crowns when viewed

from different positions (figs. 3c and 3d). Canopy depth is

depicted by darkening shades of green. Even greater realism was possible with the introduction of 32-bit color in

the early 1990s (fig. 3e). By 1998, images could be written

to files that facilitated transport to other programs. We can

now start simulations from either bare ground or existing

stand data and predict light conditions at any position on

the three-dimensional grid, now that a light simulation

model, tRAYci (Brunner 1998), has been developed and

integrated with TASS (fig. 3f). 

TASS has a wide array of available cutting prescriptions.

Single tree selection can be applied manually or randomly.

Tree list thinnings are commonly used in even-aged stand

simulations where trees are sorted by one variable (e.g.,

diameter, height, crown area, basal area) and then a specified range is removed (e.g., the largest). Spatial thinnings

such as row, checkerboard, or systematic groups are also

available. Another option mimics a field crew walking

through a stand and selecting the best tree to retain within 

a specified distance. A recent improvement for simulating

actual variable retention blocks is displayed in figure 4. An

aerial photograph (fig. 4a) or GIS map (fig. 4b) generates 

a black and white thinning layer (fig. 4c). TASS reads and

automatically scales the image to the desired plot size and

then instructs the program to treat the regions differently.

In this example, TASS removed all trees in the white areas

at age 60 and retained all trees in the black areas.We then

planted 1400 simulated western redcedar (Thuja plicata

Donn ex D. Donn) trees per hectare in the open areas (fig.

4d) and grew both cohorts for another 40 years (fig. 4e).

Summaries can be produced at any time for the entire

block, for either cohort, or for a user-specified summary

area (fig. 4f). The creation of the summary area means that

177

Figure 1—Stylized depiction of crown shape in TASS II.

Concentric lines indicate crown profile over 5 years that represents foliar volume.

Figure 2—Tree competition and mortality in TASS II.
TASS no longer requires square or rectangular plots, provided a buffer is created around the irregular polygon. 

Numerous future improvements will create a new version

(TASS III) that is better suited to the modeling of complex

stand structures. For timber supply applications, users can

now quickly estimate the simulated effects of variable retention systems on regenerated stand components with TIPSY7

(Di Lucca et al. 2004). Predictive equations that reduce

regenerated stand yields relative to those of a standard

clearcut were fit to meta-data generated by several thousand

TASS simulations. The key entry variables are species, percent retention, length of edge created around individual

trees and groups, and the average group size. If not known,

edge length can be estimated from other variables.

CASE STUDIES

Four case studies (two from the coast and two from the

Interior) illustrate how TASS helps design field installations

and assists decisionmaking. The applications focus on the

178

Figure 3—Graphic representations produced by TASS. (A) Before 1988 conversion to C language (Note that

crowns on the edge of plots grow into the opposite side(s) to avoid edge bias.); (B) Screen capture of an EGA

representation of crowns in 1988; (C) VGA representation of crowns circa 1990; (D) VGA representation at an

oblique angle; (E) true color representation of an actual 1-ha plot circa 1995; (F) True color with tRAYci active.

7 TIPSY can be freely downloaded from http://www.for.gov.bc.ca/hre/software/
design of innovative experiments in the modeling environment.

Case Study 1—Simulation of Partial Cutting in

Mountain Caribou Habitat 

In the Interior, forest management has changed the traditional habitat of mountain caribou (Rangifer tarandus

caribou) from large, contiguous expanses of mature and

old forests to a highly interspersed mosaic of even-aged

cutblocks and residual patches of mature forests. This

appears to have increased predation by wolves (Canis lupus)

and harassment by humans. Mountain caribou are now a

red listed (endangered) species in British Columbia. Early

winter forage critical to survival consists largely of arboreal

lichen species associated with old-growth conditions in the

high elevation forests of the interior Engelmann sprucesubalpine fir BEC zones (Hatter and Kinley 1999, Stevenson

et al. 2001). Mountain caribou strongly prefer lichen in the

genus Bryoria over Alectoria (Rominger et al. 1996). Bryoria

spp. occupies upper, well-ventilated portions of the canopy

and Alectoria the lower, more humid and protected regions

(Goward 1998, Campbell and Coxson 2001). A retrospective study (Lewis 2004) suggested that the transition from

Bryoria to Alectoria moves down the crown on trees that

remain after partial cutting.

Based on this information, TASS helped address the 

following question: What partial cutting regimes would

best promote the abundance and availability of Bryoria

spp.? To investigate the potential crown dynamics, a suite

of TASS simulations retained groups or single trees at levels

of 20, 40, 60 and 80 percent. In addition, we simulated 

single tree selection and three patch sizes for each level (25,

50 and 100 m square patches). The tRAYci light model

provided data for maps of proportion of above canopy light

(PACL, fig. 5) that are processed by subsequent models to

predict branch and lichen production that help identify

appropriate management strategies to achieve specific

goals.

Case Study 2—Designing the Isobel Lake Silviculture

System Experiment 

Ungulates require abundant, nutritious winter forage to

ensure high survival rates. Managers in the interior Douglasfir stands wish to increase bunch grass and reduce pine

grass by creating open stand conditions, without dramatically reducing timber supply. Unanswered questions include,

“How much should we open the stand?” and, “What is the

impact on timber supply?” TASS helped design a field experiment that tested levels of partial retention in the interior

179

Figure 4—Variable retention simulation in TASS. (A) Polygon in the Fraser Timber Supply Area near Chilliwack, BC; (B)

GIS map of opening; (C) TASS thinning image to govern removal; (D) Simulation at stand age 60; (E) Simulation at stand

age 100; (F) Summary layer and buffer strip.
Douglas-fir zone north of Kamloops, BC. A suite of simulations varied the radius of the retained patch (2-5 m) and

the distance between circular patches (12, 13, 15, 17, 20,

24, and 30 m). Figure 6a shows the pattern of retention

immediately after treatment and figure 6b the associated

PACL maps. The patterns were evaluated in terms of preferred light conditions that are known to encourage bunch

grass (roughly the left-to-right diagonal band of yelloworange). A logging protocol was developed to achieve the

intended light condition considering operational constraints.

We will compare the simulations with field results to test

model performance.

Case Study 3—Analyzing the Effect of Partial Cutting

on Spotted Owl Habitat and Timber Supply 

The range of the northern spotted owl (Strix occidentalis

caurina) extends along the west coast of North America 

to the southwest portion of British Columbia. The owl

resides in late-seral forests on the leeward side of the Coast

Mountains and both the windward and lee sides of the

Cascade Range. Forest management practices have been

modified in these areas to create habitat appropriate for

spotted owls and other species dependent on old-growth or

late-seral forest structure. Removal of high volumes of timber is permitted, but 15 of the largest 30 trees are retained

in wet maritime ecosystems (western part of the range) and

40 of the largest 80 trees in dry maritime ecosystems (eastern part of the range). The removal of low volumes of timber, about 30-percent basal area, in second-growth stands

promotes old growth conditions favorable to spotted owl.

The effectiveness of the treatments on timber production

and habitat maintenance is not known for British Columbia.

We simulated several of the proposed treatments to predict

both timber effects and habitat features. In figure 7, we

demonstrate some of the information available to forest

managers: potential distribution of snags in a mixed Douglasfir–western hemlock forest over time after the low volume

harvest (fig. 7a); canopy depth (indicated by vertical lines

below triangles) for a Douglas-fir overstory and a western

hemlock understory under a low volume removal scenario

(fig. 7b); and, the estimated timber production for different

types of regeneration strategies under high volume removal

180

Figure 5—Caribou habitat simulation in TASS for 40-percent retention. Crown representation of prethinning (A), single tree

selection (B) and 25-m retention patches (C); Proportion of above-canopy light (PACL) maps before (D) and immediately after

(E, F) treatments.
in the dry maritime ecosystems (fig. 7c). TASS estimates

dozens of other variables that allow comparisons of different

stand components of interest to forest practitioners.

Case Study 4—Designing the Silviculture Treatment 

for Ecosystem Management in the Sayward (STEMS)

Experiment

TASS computer simulations helped promote the establishment of the STEMS field installation (de Montigny 2004,

2005), a repetition of the Capitol Forest Study in Washington

State (Curtis et al. 2004, Marshall and Curtis 2005). In the

planning stage, we simulated five patch cuts across a 20-ha

block over 100 years as depicted in figure 8. The first 

replication of the STEMS project was installed in 2001 on

Vancouver Island near Campbell River, BC. Figure 9 shows

an aerial photograph of the study with three of the seven

blocks highlighted (aggregated, dispersed, and clearcut

with reserve) along with TASS representations of these

treatments. We plan to simulate the four other treatments

(extended rotation, extended rotation with commercial thinning, group selection, and modified patch cut) in the near

future. The levels of retention are 26 and 8 percent by ground

area for the aggregated and dispersed polygons, respectively.

For the purposes of this analysis, we analyzed the clearcut

as if it had zero retention because the retained group was

bounded by a road on two of the three sides and would

have little impact on the regenerated stand growth. The

merchantable volume projections for these treatments plus

the clearcut presented in figure 10 suggests that because

the percentage of retention of the dispersed treatment is

three times less than the aggregated, the yields of the regenerated stands under both overstorys will be very similar (77

and 74 percent of clearcut). However, for similar levels of

retention, TASS predicts that dispersed residual trees reduce

(text continues on p. 184)

181

Figure 6—Simulations of the Isobel Lake silvicultural treatment experiment immediately after treatment showing maps of crown cover (A) and PACL (B).
182

Figure 7—Simulation of management prescription for spotted owl habitat. (A) Distribution of snags over time;

(B) Understory and overstory canopy depth over time; (C) Volume production of partially retained overstory and

plantings of potential understory species (Hw=western hemlock, Fd=Douglas-fir).

Figure 8—Demonstration runs for the planning stage of the STEMS experiment showing structures at four ages.

Patches were removed every 15 years between ages 50 and 110.
183

Figure 9—Orthophotograph of the STEMS experiment and TASS depictions of the aggregated retention (block 1),

dispersed retention (block 3) and clearcut (block 4).

Figure 10—Simulated merchantable volume production (all trees 12.5cm+ diameter at breast height) before and

after harvesting three blocks in the STEMS field experiment. Percentages refer to level of retention by ground area.
regenerated yields more than aggregated groups because a

structure with greater length of open crown edge in the overstory is more efficient at occupying growing space. This type

of information will be useful in designing the two future

repetitions of the experiment. 

Realistic simulated scenarios in a spatial model can also

help design sampling protocols for monitoring growth and

yield. Blocks in most silviculture system trials are so large

that a systematic grid of plots must be established and

monitored over time (e.g., de Montigny 2004). A sampling

simulation program and simulated plots could ensure that

the size and number of plots established will achieve 

sampling targets now and into the future.

FUTURE DIRECTIONS

Modelers have to extend their research to meet current

and future needs of forest researchers and practitioners

involved in ecosystem management. In British Columbia,

the highest priorities are clearly predictions of growth and

yield and habitat features to ensure sustainability. Although

one model cannot answer all questions, model fidelity can

be increased by

• Measuring and modeling biological components of trees

such as foliage and roots,

• Explicitly modeling agents of mortality (e.g., beetles,

mistletoe, windthrow, root rot),

• Quantifying regeneration and understory growth,

• Developing new measures of structure, and

• Understanding ecosystem processes (light, moisture,

competition).

Modelers also need to increase cooperation with those

involved in ecosystem management by

• Participating in cooperative teams,

• Developing common terminology,

• Developing new measures for ecosystem values, and

• Sharing data and, when possible, exchanging model 

components.

SUMMARY

Computer models that are biologically realistic and 

spatially explicit can help design field installations (both

traditional and innovative). Such models can

• Clarify the objectives of the project,

• Provide an explicit range of conditions to include in both

new experiments and future replications of existing

experiments,

• Test sampling schemes for large treatment blocks.

• Establish meaningful quantitative field measures, and

• Visualize future stand structures.

When applied correctly, computer models also help land

managers in developing rational operational guidelines and

policy for both timber and nontimber resources. Models can

predict tree and stand conditions not available from longterm data, and provide information in support of sustainability (e.g., measures of habitat and timber).

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186
1 Research Forester, USDA, Forest Service, Pacific Northwest Research Station, 3200 Jefferson Way, Corvallis, OR 97331, USA. Email: tspies@fs.fed.us

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Scaling Up From Stands to Landscapes

Thomas A. Spies1

INTRODUCTION

Issues of forest sustainability are inherently issues 

of scale (Spies and Johnson 2003). Forest structure and

composition vary over a wide range of spatial and temporal

scales. Likewise, forest goods and services vary with scale

and with objectives and values of different forest owners.

Many gaps in our understanding of sustainability problems

have risen from the changing priorities of society for goods

and services from forests. For example, the biodiversity

and recreation values of forests have increased worldwide. Experimental approaches can be used to identify the

most effective management practices to meet the new goals;

however, classic experiments are difficult or impossible to

ABSTRACT

Stand-level experiments are critical to understanding the effects of innovative silvicultural practices on biological diversity. However, stand-level information is not sufficient to understand how management practices influence ecological, economic, or social outputs and outcomes. Landscape and regional studies are also needed, but experimental approaches are

difficult to impossible at broad spatial scales. Consequently, other research approaches are needed at this scale, including

modeling, retrospective studies, and monitoring of natural experiments. In this paper I examine some lessons learned from

landscape-scale modeling studies that incorporate stand-level information. In particular, I focus on what we have learned

from the Coastal Landscape Analysis and Modeling Study (CLAMS) as it pertains to estimating the effects of different forest management practices on biological diversity and timber production across landscapes. The simulations indicate that

ecological effects of stand-level practices at landscape scales are influenced by (1) area of treatment as proportion of total

area; (2) environmental variation; (3) diversity of initial biotic conditions (including vegetation and animals); (4) species

and ecosystem processes; (5) dispersal effects (6) rate of change and time frame of analysis; (7) stochastic processes, e.g.,

disturbance; and (8) management practices and patterns. Large multi-owner landscapes, where many of the above influences

are important, pose significant technical and institutional challenges to implementing new approaches to balancing ecosystem values. Significant advances can be made if we can do a better job of coordinating and integrating different research

approaches to address sustainability questions that span multiple spatial and temporal scales. 

KEYWORDS: Forest biodiversity, multi-ownership landscapes, spatial simulation models, Pacific Northwest.

187

implement at broad scales, where many ecological and

social processes operate (fig. 1). Consequently, other scientific approaches such as historical studies, long-term monitoring, and simulation modeling are needed to address the

multi-scale nature of forest sustainability problems. 

Over the last several years, the Coastal Landscape

Analysis and Modeling Study (CLAMS) conducted research

on scaling problems and policy effects in the Oregon Coast

Range (Spies et al. 2002) (see also www.fsl.orst.edu/clams).

Based on this experience, I will briefly identify several

influences that must be considered when scaling up standlevel information to landscape and regional scales. 
INFLUENCES ON EFFECTS OF

STAND-LEVEL PROCESSES AT

LANDSCAPE SCALES

The following factors influence how stand-level processes

and patterns affect processes and patterns at broader scales. 

1. Area of treatment as proportion of total area. It is

easy to forget that the landscape-scale effects of stand

manipulations depend on the total area treated. For

example, thinning thousands of hectares of young 

stands on federal lands in the Coast Range may sound

like a lot, but when those hectares are a part of a 2.5 

million hectare province, the effects of the treatments 

on habitat can be small at the scale of the province. 

2. Environmental variation. Reactions of forest vegetation to human and natural disturbances will vary with

site productivity, climate zone and topography (Wimberly

and Spies 2001a). Most experimental studies can only

capture a small portion of the environmental variability

that occurs within a region. Consequently, one must

exercise caution when extrapolating results to large,

diverse landscapes and regions.

3. Initial biotic conditions. The response of plants and

animals to silvicultural manipulations will depend on 

the organisms that are present on the site at the time of

the treatment. Extrapolating treatment effects to large

scales must take into account the diversity of stand conditions. New models such as Gradient Nearest Neighbor

(Ohmann and Gregory 2002) that use remote sensing

and geographic information systems provide a good way

of retaining and spatially distributing the variation in

vegetation that is found in a landscape. 

4. Variation in responses of species and ecosystems.

Again, it may seem obvious that not all species will

respond to management practices and forest structure in

the same way (Johnson and O’Neil 2001). However, this

fundamental truth is often forgotten in debates about 

forest management impacts. 

5. Dispersal effects. Most of the effects I have mentioned

so far are simply additive effects—if one knows the areas

of treatment and the species involved, it is possible to

estimate effects with some certainty. In other words,

knowledge of spatial arrangement of vegetation at landscape scales is not needed. When it comes to plant

188

Figure 1—Spatial extent of management and natural processes and typical spatial extent of manipulative

field experiments.
establishment and animal colonization, however, it is

important to know the landscape pattern of seed sources

or source populations around a particular site. The patterns of seed sources in a landscape can affect the pattern

of forest development even for such common species 

as western hemlock (Tsuga heterophylla (Raf.) Sarg.)

(Wimberly and Spies 2001b). 

6. Rate of change and time frame of analysis. Most of

our long-term studies of ecosystems are less than 25

years old, and few forestry and agricultural long-term

studies are more than 100 years old. Ecologists are well

aware that early responses to experimental treatments

may change with time. New species may colonize a site

and competitive interactions may cause some species to

drop out and others to assume dominance. These patterns can take decades and centuries to play out. In the

case of thinning to accelerate the development of oldgrowth forest structure, changes may take more than 

a century to appear (Garman et al. 2003). 

7. Stochastic processes. Although growth patterns and

species compositional changes resulting from physiological and competitive processes may be relatively easy

to predict during stand development, it is far more difficult to predict disturbances or climate changes that can

totally alter the course of development of a forest stand

or landscape. We can try to estimate the probability of

fire, insects, disease, and wind, but ultimately we really

can not predict when and where these disturbances will

occur. At landscape scales, these types of dynamics must

be handled using probabilistic models and scenario

analysis that identify alternative pathways. 

8. Management practices and patterns. Multi-ownership

landscapes pose special challenges for scaling up the

effects of forest management. Management goals (Spies

et al. 2002) and practices can differ widely among landowners. Policies and plans that owners operate under may

look very different when implemented on the ground

than they do on paper. Policy changes can occur for

economic and political reasons that are impossible to

predict. The effects of management practices may be a

result of interactions between environment and forest

conditions. Biophysical information needed to estimate

management effects is typically not available in a uniform

way in multi-ownership landscapes. Finally, simulation

models that can integrate stand and landscape processes

across large forests are only in the early stages of development. 

CONCLUSION

Scaling up from stands to landscapes and regions is not

easy to do. Yet, we must undertake this task to more fully

understand how forest management practices affect biodiversity and other values. The variety of influences on the

expression of stand-level process and patterns at broad spatial and temporal scales argues strongly for using multiple

research approaches to fill critical information gaps. Too

often research approaches such as stand-level experiments,

retrospective studies, and landscape simulation models are

not carried out in a coordinated fashion. Information from

one type of approach cannot be readily linked to another.

This reduces the effectiveness of our efforts to understand

how human activities influence species and ecosystems.

Significant advances can be made if we can do a better job

of coordinating and integrating different research approaches

to address sustainability questions that span multiple spatial

and temporal scales. 

ACKNOWLEDGMENTS

I would like to acknowledge the assistance of Rob Pabst

in preparation and review of this paper.

REFERENCES

Garman, S.L.; Cissel, J.H.; Mayo, J.H. 2003. Accelerating 

development of late-successional conditions in young

managed Douglas-fir stands: a simulation study. Gen.

Tech. Rep. PNW-GTR-557. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station. 57 p.

Johnson, D.H.; O’Neil, T.A., eds. 2001. Wildlife habitat 

relationships in Oregon and Washington. Corvallis, OR:

Oregon State University Press. 

Ohmann, J.L.; Gregory, M.J. 2002. Predictive mapping 

of forest composition and structure with direct gradient

analysis and nearest neighbor imputation in coastal

Oregon, USA. Canadian Journal of Forest Research. 

32: 725-741.

Spies, T.A.; Johnson, K.N. 2003. The importance of scale 

in assessing the compatibility of forest commodities and

biodiversity. In: Monserud, R.A.; Haynes, R.W.; Johnson,

A.C., eds. Compatible forest management. Dordrecht,

The Netherlands: Kluwer Academic Publishers: 211-235.

189
Spies, T.A.; Reeves, G.H.; Burnett, K.M.; McComb, W.C.; 

Johnson, K.N.; Grant, G.; Ohmann, J.L.; Garman, S.L.;

Bettinger, P.S. 2002. Assessing the ecological consequences of forest policies in a multi-ownership province

in Oregon. In: Liu, J.; Taylor, W.W., eds. Integrating

landscape ecology into natural resource management.

Cambridge, United Kingdom: Cambridge University

Press: 179-207.

Wimberly, M.C.; Spies, T.A. 2001a. Influences of environment and disturbance on forest patterns in coastal

Oregon watersheds. Ecology. 82: 1443-1459.

Wimberly, M.C.; Spies, T.A. 2001b. Modeling landscape 

patterns of understory tree regeneration in the Pacific

Northwest, USA. Applied Vegetation Science. 

4: 277-286.

190
1 Extension Silviculture and Wildland Fire Specialist, Department of Forest Resources, Oregon State University, Corvallis, OR 97331, USA. 

Email: stephen.fitzgerald@oregonstate.edu

2 Extension Silvicultural Specialist and 3 Research Assistant, Department of Forest Science, Oregon State University, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Simulating Structural Development and Fire 

Resistance of Second-Growth Ponderosa Pine Stands 

for Two Contrasting Stand Treatments

Stephen Fitzgerald,1 Douglas A. Maguire,2 and Ryan Singleton3

INTRODUCTION

The typical presettlement ponderosa pine (Pinus 

ponderosa P.&C. Lawson) forest consisted of open stands,

dominated by a few large trees often in groups, with little

understory vegetation and maintained by frequent lowintensity fires (Bork 1984, Weaver 1943, Youngblood et al.

2004) (fig. 1). Historically, tree density in old-growth ponderosa pine stands in Oregon varied from 12 to 40 trees per

acre (Munger 1917). However, the structural development

of ponderosa pine forests in Oregon has changed significantly over the past century because of disruptions to the

natural fire regime and changes in stand and landscape

structure from timber harvesting, grazing, and other land

use (Hessburg and Agee 2003). Recent landscape-scale

assessments have shown that stand density and fuel accumulation have increased significantly compared to historical conditions, and current conditions could potentially

support wildfires that are lethal to trees and other vegetation (Gast et al. 1991, Quigley and Cole 1997, Schmidt 

et al. 2002). 

In central Oregon, a significant portion of the old-growth

ponderosa pine forest was heavily logged 80 years ago.

The landscape was left to naturally regenerate, resulting in

ABSTRACT

We simulated the growth, development, and fire-resistant of 80-year-old second-growth ponderosa pine (Pinus ponderosa

P.&C. Lawson) stands in central Oregon for two contrasting treatments: heavy, low thinning and single-tree selection. Our

analysis shows that heavy, low thinning that leaves codomiant and dominant trees improved fire resistance. Single-tree

selection, with the goal of producing stands uneven-sized distribution decreases fire resistance over the long run. 

KEYWORDS: Ponderosa pine, fire resistance, stand structure.

191

dense, even-aged stands which today are increasingly

susceptible to insect and disease outbreaks and stand

replacement fire. These stands differ dramatically from

historical conditions, so their future structural development

is largely unknown. Silvicultural intervention, however,

provides an opportunity to influence that development 

for various objectives, including improving stand and landscape resistance to wildfire. Forest structure is an important

aspect of stand and landscape resistance to wildfire (Graham

et al. 2004). Various stand and fuel attributes have been

summarized by Agee (2002) into “guiding principles” for

creating forests that are more fire resistant (table 1). Managers

can use these guidelines for developing prescriptions for

stands where increasing fire resistance is a primary objective, such as within the wildland-urban interface. 

STUDY AND SITE DESCRIPTION

The fire-resistance analysis presented in this paper is

part of a larger study we installed in 2002 to explore silvicultural treatments that advance second-growth ponderosa

pine forests toward a more sustainable and biologically

diverse condition. 

The study was installed in pure ponderosa pine forests

of central Oregon within the pumice soil zone. Soils are
192

Figure 1—Harold Weaver (1930s) in a typical old-growth ponderosa pine forest on the Klamath

Indian Reservation circa 1930s. (Photo courtesy of Bureau of Indian Affairs)

coarse textured with high infiltration rates and low fertility.

The soil is the result of volcanic deposition from Mount

Mazama 7,700 years ago and from other volcanic events in

the Cascade Range. Precipitation is approximately 46 to 51

cm. Site quality, as measured by Barrett’s (1978) site index,

is 80-90. The study site is on a ponderosa pine/bitterbrush/

Idaho fescue plant association (Volland 1985) at approximately 1280 m in elevation. 

Our objective was to test differences in stand structural

development over time using four silvicultural alternatives

in second-growth, even-aged ponderosa pine stands: (1) no

treatment; (2) group selection, cutting 1 to 2-ha openings

(10 to 20 percent of area in openings) and with low thinning of matrix area between openings (SDI 272 to 346/ha

(110 to 140/ac)); (3) heavy low thinning (SDI 146 to 222/ha

(60 to 90/ac)) leaving the “best” dominant and codominant

trees at relatively low stand densities; and (4) single-tree

selection removing trees evenly across all diameter classes

(SDI 185 to 272/ha (75 to 100/ac)) by using a combination

of high and low thinning methods to thin evenly across all

crown classes, leaving the most vigorous trees, and creating

a stand that was uneven-sized with the goal of producing

an uneven-aged stand. Low thinning primarily removes

trees in the suppressed, intermediate, and codominant crown

classes, leaving the more vigorous codominant and dominant

trees. High thinning removes a small percentage of trees in

the codominant and dominant crown classes freeing up site

resources and releasing other healthy intermediate, codominant, and dominant trees. 
Treatments were randomly assigned in each of three

blocks across the central Oregon region (3 blocks x 4 treatments) for a total of 12 treatment units. Pretreatment data

was collected during the summers of 2002 and 2003. The

entire study encompasses over 244 ha. Treatment units 

varied in size from 16.1 to 40.5 ha. Two hundred and forty

five 0.081-ha plots were established across the entire study

area to obtain uniform coverage, with 16 to 25 plots in

each treatment unit depending on unit size. On each plot,

trees per hectare, tree diameter, crown class, mistletoe

rating, and damage or defect and whether the tree was

marked for retention or to cut were recorded for each tree.

Tree heights and tree crown dimensions (width, length,

crown base height (CBHt)) were recorded for three trees

per plot (suppressed, codominant, and dominant). Canopy

bulk density (CBD) is defined as the amount of foliage

(including small twigs and branches) in kilograms for a

given volume of crown. The CBD was not directly measured on our study plots, but was calculated by the Fire and

Fuels Extension Model to the Forest Vegetation Simulator

(refer to next section for model descriptions). Also, all snags

and their attributes (diameter, height, and decay class) were

measured. On all other plots, downed wood piece size

(diameter and length) and decay class were measured. The

percentage of vegetative understory (forbs, grasses, and

shrubs) and the number of tree seedlings below breast

height were inventoried on two 0.004-ha subplots. Trees in

each treatment unit were either marked for retention or to

cut according to predetermined prescriptions and density

targets. Treatment units will be harvested in 2005. 

TREATMENT SIMULATION OBJECTIVES

AND PARAMETERS

To simplify our analysis, we evaluated the fire resistance of stands managed for two contrasting treatments:

heavy, low thinning and single-tree selection using high

and low thinning to achieve an uneven diameter distribution. We did not simulate the growth and development of

stands in the control and group selection treatments.

A stand’s resistance to fire is dependent on the amount

of surface (i.e., needles and branches), ladder, and canopy

fuels, as well as various stand attributes including stand

density, average diameter, height to the base of the canopy

and canopy bulk density (Agee et al. 2000, Graham et al.

2004). Ladder fuels are often comprised of shrubs and

small to medium size trees which can convey a surface 

fire up into the overstory canopy. 

We input our pretreatment plot data and simulated the

growth and development of these stands using the Forest

Vegetation Simulator (FVS) (Stage 1973, Wycoff et al.

1982). Stands were projected 40 years in the future. The

Fire and Fuels Extension Model to FVS was used to simulate fuel dynamics and potential fire behavior attributes

over time (Reinhardt and Crookston 2003) including flame

length under severe and moderate fuel moisture and weather

conditions, and torching and crowning indices. Flame lengths

under severe and moderate conditions (temperature, wind

193

Table 1—Guiding principles for creating fire-resistant forests

Principle Effect Advantage Concerns

Reduce surface Reduces potential Control easier, less Surface disturbance, less with 

fuels flame length torching fire than other techniques

Increase height to Requires longer Less torching Opens understory, may allow 

live crown flame length to surface wind to increase

begin torching

Decrease crown Makes tree-to-tree Reduces crown fire Surface wind may increase 

density crown fire less potential and surface fuels may be 

probable drier

Keep larger trees Thicker bark and Increases Removing smaller trees is 

taller crowns survivability of trees economically less profitable

Adapted from Agee 2002.
speed, fuel moistures) are defined as follows and are

default values in the model:

Temp.° Wind Speed Fuel

Condition (Celsius) (km/hr) Moisture4

Severe 21.1 32.2 Very dry

Moderate 21.1 9.7 Moist

The torching index is the 6.1-meter wind speed at

which torching of the lower tree canopy would be initiated.

Similarly, crowning index is the 6.1-meter wind speed

required to initiate an active crown fire. 

Thinning treatments were simulated by instructing the

model to remove trees that were marked for removal on

study plots. Because trees less than 13 cm were not operationally marked in the study, we instructed the model to

remove all trees less than 13 cm for the wide thinning treatment and to remove 50 percent of the trees less than 13 cm

for the single-tree selection treatment. The goal for the

single-tree selection treatment was to create a more open but

uneven-sized stand by keeping some of the viable saplings

and regeneration and maintaining healthy and vigorous

trees across all diameter classes. 

Because thinning activities creates slash (surface fuels)

and, therefore, can affect fire behavior by increasing flame

length and decreasing torching and crowning indices

(Graham et al. 2004), we simulated a pile-and-burn treatment

(in the 2004 simulation year) to reduce these understory

fuels following thinning. 

Stand structural differences and fire resistance were

evaluated immediately before (2002 simulation year) and

after thinning and pile-and-burn treatments (2005 simulation year) and after 10, 20, 30 and 40 years of simulation. 

RESULTS AND DISCUSSION

Stand Structural Attributes

Table 2 displays stand structural attributes for the simulation period. The heavy low thinning treatment dramatically reduced trees per hectare (t/ha) from 366 to 107 and

increased quadratic mean diameter (d.b.h.) from 27.2 to

39.1 cm. After 40 years, quadratic mean diameter increased

to 50.3 cm, which is close to the diameter of old-growth

ponderosa trees for this site (figs. 2a,b,c). In contrast, the

combination of high and low thinning in the single-tree

selection treatment increased average stand diameter only

slightly from 23.9 to 25.9 cm because some of the larger

trees were removed and some smaller trees retained, including regeneration, which tends to lower average tree size

(figs. 3a,b,c). After 40 years the average tree diameter

increased to 37.1 cm. As expected, heavy, low thinning left

fewer trees per hectare than the single-tree selection treatment (107 vs 501, respectively). After 40 years, trees in the

heavy, low thinning treatment averaged 13.2 cm larger than

those in the single-tree selection treatment.

194

Table 2—Simulated stand attributes for the 40-year projection period for heavy, low 

thinning and single-tree selection treatments

Heavy, low thin Single-tree selection

Year T/ha D.B.H. CBHt CBD T/ha D.B.H. CBHt CBD

2002 366 27.2 8.5 0.042 501 23.9 6.4 0.043

2005 107 39.1 12.5 .019 215 25.9 8.8 .022

2012 106 41.4 12.5 .019 210 28.2 8.8 .024

2022 104 44.5 12.8 .019 207 30.9 8.5 .027

2032 101 47.5 12.8 .019 200 34.0 6.4 .029

2042 99 50.3 12.8 .019 195 37.1 6.5 .029

T/ha = Trees per hectare

D.B.H. = Quadratic mean diameter at breast height in centimeters

CBHt = Crown base height in meters

CBH = Canopy bulk density in kilograms per cubic meter

4 See Reinhardt and Crookston (2003) for the 1-, 10-, 100-, and 1000-hour fuel moisture content under very dry and moist conditions.
195

Figure 2—Heavy, low thinning treatment: (A) Pretreatment stand structure; (B) Post-thinning stand structure; (C) Stand structure after 

40-year simulation period.

Figure 3—Single-tree selection treatment: (A) Pretreatment stand structure; (B) Post-thinning stand structure; (C) Stand structure after 

40-year simulation period.

A B

C

A B

C
Heavy, low thinning increased the height to the base of

the crown (CBHt) from 8.5 to 12.5 m because larger codominant and dominant trees were left, and CBHt did not

increase much after that over the 40-year simulation period.

For the single-tree selection treatment, crown base height

increased moderately from 6.4 to 8.8 meters, but decreased,

as expected, over time to 6.4 m because of the presence of

regeneration (i.e., ladder fuels) that grew into the lower

canopy. 

Canopy fuel, as measured by canopy bulk density (CBD),

was reduced by half in both stand treatments, and it

remained constant for the wide thinning treatment, but

increased in the single-tree selection over the 40-year

simulation period. 

Fire Behavior Attributes

Table 3 displays fire behavior attributes over the 40-

year simulation period. Flame length is a predictor of fireline intensity, or the amount of heat released per unit area

(Rothermal and Deeming 1980). Longer flame lengths

indicate higher intensity, which are often more lethal to

trees and other vegetation. 

For both treatments, flame length under severe conditions increased immediately after treatment. This reflects

increased wind speed and more thorough drying of surface

fuels following thinning, which opens up canopy. Over

time, flame lengths decrease, but flame lengths in the heavy,

low thinning tend to be shorter than in the single-tree selection treatment. Flame lengths under moderate fuel moisture

and weather conditions were similar for both treatments. 

The torching index decreased immediately after thinning for both treatments due to the more open stand conditions. Over time, the torching index increases, but increases

to a greater degree in the heavy, low thinning (32 km/hr at

year 40). This indicates reduced potential for torching in

the heavy, low thinning compared to the single-tree selection treatment (16.6 km/hr at year 40). 

The crowing index increased immediately after thinning

for both treatments and then decreases moderately over the

40-year simulation period. However, the crowning index is

significantly higher in the heavy, low thinning treatment

(120.8 km/hr at year 40) over the simulation period, indicating a much greater resistance to active crown fire behavior compared to the single-tree selection (91.0 km/hr at

year 40). This is due to the lower canopy height from the

presence of smaller trees and to the higher stand density

and canopy fuels in the single-tree selection treatment. 

In the single-tree selection treatment, we simulated 

only one thinning entry. The purpose of this treatment is 

to eventually produce an uneven-aged stand. In practice,

uneven-aged management would entail multiple thinning

entries every 10 to 20 years to remove trees across the entire

diameter distribution and to create openings for additional

regeneration (a new age class of trees). Continued thinning

to create a more balanced uneven-aged stand would most

likely lead to lower fire-resistance as additional regeneration is recruited and fuel ladders are created.

196

Table 3—Simulated fire behavior attributes for heavy, low thinning and single-tree selection treatments 

Heavy, low thin Single-tree selection

Flame lengtha Flame length

Year Severe Moderate Torch Crown Severe Moderate Torch Crown

indexb index index index

2002 3.3 0.9 31.9 69.7 4.6 0.9 21.7 69.7

2005 4.4 .8 25.1 124.3 5.0 .8 19.2 112.1

2012 3.2 1.1 30.3 122.0 .8 1.0 21.9 103.2

2022 3.1 1.1 31.7 120.9 3.8 1.0 22.2 95.0

2032 3.0 1.1 32.0 120.8 4.3 1.0 16.6 91.0

2042 3.0 1.1 32.0 120.8 4.3 1.0 16.6 91.0

a Flame lengths are in meters.

b Torching and crowning indices are in kilometers per hour.
CONCLUSIONS

Our simulation results show that thinning methods can

significantly affect stand structural attributes, which in turn

affect resistance to wildfire. Low thinning to a wide spacing

increased overall resistance to wildfire by decreasing flame

lengths under severe conditions, and increasing torching

and crowning indices compared to the single-tree selection

treatment. Treatments that retain the largest trees, increase

canopy height by reducing ladder fuels, and reduce canopy

fuels will improve resistance to wildfire (Agee 2002). Also,

retaining the larger trees will improve their survival because

they have thicker bark. 

The results from this analysis are preliminary and are

based on simulation results only. Although the structural

attributes of stands can affect fire resistance, other landscape and site factors, such as overall fuel loading in the

surrounding landscape, extreme weather conditions, and

site factors such as slope, aspect and elevation can also

affect fire behavior and tree and stand survivability. 

REFERENCES

Agee, J.K. 2002. Fire behavior and fire-resilient forests. 

Pages. In: Fitzgerald, S.A., ed. Fire in Oregon’s forests:

risk, effects, and treatment options. A synthesis of 

current issues and scientific literature. Special report.

Portland, OR: Oregon Forest Resources Institute. 

119-126.

Agee, J.K.; Bahro, B.; Finney, M.A.; Omi, P.N.; Sapsis, 

D.B.; Skinner, C.N.; vanWagtendonk, J.W.; Weatherspoon,

C.P. 2000. The use of shaded fuelbreaks in landscape

fire management. Forest Ecology and Management.

127: 55-66.

Barrett, J.W. 1978. Height growth and site index curves for 

managed, even-aged stands of ponderosa pine in the

Pacific Northwest. Res. Pap. PNW-RP-232. Portland,

OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Forest and Range Experiment

Station. 14 p.

Bork, J.L. 1984. Fire history in three vegetation types on 

the east side of the Oregon Cascades. Corvallis, OR;

Oregon State University. 94 p. Ph.D. dissertation.

Gast, W.R.; Scott, D.W.; Schmitt, C.; Clemens, D.; Howes, 

S.; Johnson, C.G.; Mason, R.; Mohr, F.; Clapp, R.A.

1991. Blue Mountains forest health report: new perspectives in forest health. Pacific Northwest Region,

Malheur, Umatilla, and Wallowa-Whittman National

Forests. 191 p.

Graham, R.T.; McCaffrey, S.; Jain, T.B., tech. eds. 2004. 

Science basis for changing forest structure to modify

wildfire behavior and severity. Gen. Tech. Rep. 

RMRS-GTR-120. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain

Research Station. 43 p.

Hessburg, P.F.; Agee, J.K. 2003. An environmental narrative of Inland Northwest United States forests. Forest

Ecology and Management. 178: 23-59.

Munger, T.T. 1917. Western yellow pine in Oregon. USDA

Bulletin 417. Washington, DC: Goverment Printing

Office. 48 p.

Quigley, T.M.; Cole, H.B. 1997. Highlighted scientific 

findings of the interior Columbia Basin ecosystem

management project. Gen. Tech. Rep. PNW-GTR-404.

Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 34 p.

Reinhardt, E.D.; Crookston, N.L. 2003. The fire and fuels 

extension to the Forest Vegetation Simulator. Gen. Tech.

Rep. RMRS-GTR-116. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Research

Station. 209 p.

Rothermel, R.C.; Deeming, J.E. 1980. Measuring and interpreting fire behavior for correlation with fire effects.

Gen. Tech. Rep. INT-GTR-93. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain

Forest and Range Experiment Station. 4 p.

Schmidt, K.M.; Menakis, J.P.; Hardy, C.C.; Hann, W.J.; 

Bunnell. D.L. 2002. Development of coarse-scale 

spatial data for wildland fire and fuel management.

Gen. Tech. Rep. RMRS-87. Fort Collins, CO: U.S.

Department of Agriculture, Forest Service, Rocky

Mountain Experiment Station. 41 p. +CD.

Stage, A.R. 1973. Prognosis model for stand development. 

Res. Pap. INT-137. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station. 32 p.

197
Volland, L.A. 1985. Plant associations of the central 

Oregon pumice zone. R6-ECOL-104-1985. Portland,

OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Region. 138 p.

Weaver, H. 1943. Fire as an ecological and silvicultural 

factor in the ponderosa pine region of the Pacific slope.

Journal of Forestry. 41(1): 7-15.

Wycoff, W.R.; Crookston; N.L.; Stage, A.R. 1983. User’s 

guide to the stand prognosis model. Gen. Tech. Rep.

INT-GTR-133. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station. 112 p. 

Youngbood, A.; Max,T.; Coe, K. 2004. Stand structure in 

eastside old-growth ponderosa pine forests of Oregon

and northern California. Forest Ecology and Management.

199: 191-217.

198
1 U.S. Department of Agriculture, Forest Service, North Central Research Station, 1831 Hwy. 169 E., Grand Rapids, MN 55744, USA. 

Email: dlytle@fs.fed.us

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Predicting the Cumulative Effects of Forest 

Management in a Multi-Ownership Forest Landscape

David Lytle1

Land management agencies are often asked to consider how their management activities interact with those of neighboring landowners to affect the ecological attributes of forest landscapes. However, predicting the responses of multi-ownership forest landscapes to management is difficult. As a result, analyses of the cumulative effects of management are often

informal, and future landscape conditions are poorly understood. Managers from public land management agencies in

Minnesota and Ontario, Canada, are using an integrated framework to achieve common goals and better coordinate where

goals differ. To support this framework, I have used LANDIS, a landscape-scale, forest dynamics model, to evaluate the

cumulative effects of forest management in a 230 000 ha landscape managed for wilderness, timber, and recreation. Scenarios

developed from current and proposed management plans were used to project the effects of 100 years of management on

key forest attributes. These scenarios also contrast the current fire suppression policy with options that include prescribed

and natural fire use. Compared to scenarios without harvest or fire, the current plans yield lower fuel loads and fire risk as 

a result of reduced stand ages and lower abundances of conifer fuel ladders. Scenarios with extended harvest rotations yield

greater fire risk when compared to current plans, although prescribed fire use offsets these differences. Management of

wilderness areas has a large impact on the landscape. The current fire suppression policy produces high fire risk within the

wilderness, and results in the loss of early successional species; increased use of prescribed and natural fire reverses these

trends. 

199
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1 Research Associate, 2 Hayes Professor of Silviculture and Forest Biometrics, and 3 Research Assistant, Department of Forest Science, Oregon State

University, Corvallis, OR 97331, USA. Email of corresponding author: doug.mainwaring@oregonstate.edu

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Projections of Future Overstory Stand Structure 

and Composition Following Variable-Retention Harvests

in the Northwestern United States

Paul Schwarz,1 Douglas A. Maguire,2 and Doug Mainwaring3

INTRODUCTION

Forest management on federally owned land in the

northwestern United States has changed significantly since

the adoption of the Northwest Forest Plan in 1994. Prior 

to implementation of this plan, the dominant management

regime in the Douglas-fir dominated forests (Pseudotsuga

menziesii (Mirb.) Franco) of the Oregon and Washington

Cascades was clearcutting followed by planting. Fast-growing plantations successfully fulfilled the timber management goal mandated by previous federal legislation. As

these stand conversions grew in number and dominated a

larger portion of the landscape, the long-term effects on

other ecosystem components came into question (Christensen

ABSTRACT

Among the motivations behind the 1994 Northwest Forest Plan was a growing awareness that the Pacific Northwestern

landscape was becoming a patchwork of clearcuts and even-aged forest plantations, the latter with diminished structural

diversity relative to presettlement forests. Potential deleterious effects of this patchwork landscape on wildlife populations

and general biodiversity led to a mandate for minimum levels of green-tree retention within harvest units, in both dispersed

and aggregated patterns. The Demonstration of Ecosystem Management Options (DEMO) study was initiated to address the

lack of information on the efficacy of variable-retention harvests in providing habitat for target species. The DEMO study

incorporated six different treatments in six blocks throughout Oregon and Washington. The following six treatments were

specified by percentage of retained basal area and were implemented on 13-ha treatment units: (1) 100 percent; (2) 75-percent aggregated (three 1-ha cut patches); (3) 40-percent dispersed; (4) 40-percent aggregated (five 1-ha residual patches);

(5) 15-percent dispersed; and (6) 15-percent aggregated (two 1-ha residual patches). All treatments except the control (100-

precent retention) were planted in the harvested portions, so a new cohort of planted stock and natural regeneration will

rapidly dominate harvested areas. The future structure of each of the 36 stands was projected with the ORGANON growth

and yield model, assuming various management regimes. Visual representation of future stand structure was done with

Envision software to facilitate communication among the scientists and managers comprising the multi-disciplinary DEMO

team. These projections and visual representation of the stands will help the DEMO team design the next set of treatments

that were intentionally left undefined at the inception of the study.

KEYWORDS: Variable retention, stand projection, growth model, simulation, visualization, yield.

201

et al. 1996). The northern spotted owl (Strix occidentalis

caurina) was eventually listed as a threatened species due

to the loss of habitat resulting from these stand conversions

(Thomas et al. 1990). 

Shortly thereafter, all federal lands within the Douglasfir region were placed under management guidelines specified in the 1994 Northwest Forest Plan (Tuchmann et al.

1996). Emphasizing ecosystem management, this plan halted

all clearcutting in harvest units within the owl’s range, calling instead for variable retention harvests. According to the

plan, at least 15 percent of the area in each harvest unit must

be made up of retained green trees. In addition, 70 percent

of this retention must be in aggregates 0.2–1.0 ha or larger,
with the remainder dispersed either as single trees or in

small clumps <0.2 ha in size. Moreover, to the extent possible, retention should include the largest and oldest live,

decadent or leaning trees, and hard snags. The intent was to

retain residual trees indefinitely (Tuchmann et al. 1996). 

Although the retention standards of this plan were based

on the best information available at the time, no experiment

or observational study had ever determined whether this

level of retention provided meaningful or sufficient habitat

necessary to preserve the organisms and ecological processes

for which they were designed. As a starting point for addressing this question, the Demonstration of Ecosystem Management Options (DEMO) study was initiated (Franklin et al.

1999). Replicated at six locations throughout the Douglasfir region (i.e., Oregon, Washington) (fig. 1), this interdisciplinary study was designed to test whether it is possible

to balance timber production with maintenance of biodiversity in mature Douglas-fir forests. The primary objective 

of the study was to determine the response of vegetation,

ectomycorrhizal fungi, canopy arthropods, small mammals,

salamanders, and birds to different levels and patterns of

retention, and to assess human perception of their visual

quality. DEMO also has a long-term objective to determine

what effect subsequent stand development has on these

responses over time (Aubry et al. 1999, Halpern and

Raphael 1999).

Each replication of this study included the same six

treatments on 13-ha units: (1) an unharvested control; (2)

75-percent retention with the harvested area distributed

among three 1-ha patch cuts (Retained trees were aggregated in the matrix surround the patch cuts.); (3) 40-percent

dispersed retention; (4) 40-percent retention with retained

trees distributed among five equally spaced 1-ha aggregates; (5) 15-percent dispersed retention; 6) 15-percent

retention with retained trees distributed between two equally

spaced 1-ha aggregates (fig. 2). On dispersed retention units,

residual trees were evenly distributed. These treatments

were harvested in 1997 and 1998, and harvested areas were

replanted with a uniform mix of species prescribed for each

block.

The planting density, generally between 500 and 750

trees per hectare, was consistent with the stated goal of

balancing timber production with maintenance of biodiversity. However, timber harvests in these units were intended

as an initial set of alternative silvicultural treatments, and

no attempt was made to specify a full silvicultural regime

or system. In this approach, further treatments could benefit from initial responses to harvest, changing scientific

perspective, and changing public perceptions. Unknowable

responses to the initial treatments and the long-term nature

of this type of study require flexibility in design of a treatment regime. However, the new cohort in these forests will

develop quickly to create a relatively closed canopy in 15

to 25 years, potentially causing a drastic change in ground

vegetation and the many organisms that rely on the understory for food or shelter (e.g., Alaback 1982). The ability

to predict future stand structures will aid decisionmaking

about what future management actions, if any, should be

taken in these treatment units. This peek into the future is

especially important in a long-term, multidisciplinary study,

where competing research objectives, multi-institutional

involvement, and personnel turnover make quick action

difficult (Franklin et al. 1999).

202

Figure 1—Locations of the six DEMO blocks. CF: Capitol Forest; BU:

Butte; PH: Paradise Hills; LW: Little White Salmon; WF: Watson Falls;

DP: Dog Prairie.
Given the generally accepted influence of forest structure on dependent biotic communities, predicting the likely

effects of any silvicultural regime requires predicting the

subsequent structure and dynamics of the vegetation.

Although quantitative descriptors may be sufficient for

some foresters and forest ecologists, they are less useful 

for managers and scientists working with other organisms.

Stand and landscape visualization software was developed

to surmount this communication challenge. Because visualization software converts stand variables and tree dimensions into a three-dimensional visualization, it provides a

means by which forest structure can be inferred from very

detailed, quantitative description that would otherwise be

difficult to interpret (McGaughey 1997). Coupled with an

appropriate growth model, three-dimensional depictions of

future stand structure provide insight into the ramifications

of alternative silvicultural treatments. The objectives of this

paper are to (1) link the tools necessary for projecting the

future structure of DEMO treatments units, (2) produce

visualizations of future structures of each unit, (3) evaluate

alternative treatment regimes, (4) facilitate planning by the

multidisciplinary DEMO team, and (5) begin discussion on

specifications for variable-retention silvicultural systems.

METHODS

Data Collection

Data on tree species composition and stand structure

were collected from 0.04-ha circular plots on a 40-m sampling grid within each treatment unit (Aubry et al. 1999).

Diameter at breast height (1.3 m, d.b.h.) was measured on

all trees, and height and height to crown base were measured on up to 40 trees per species per treatment unit. Trees

chosen for this subsample were distributed evenly across

the diameter distribution of each treatment. Missing heights

and heights to crown base were estimated by regression

equations developed for each treatment unit and using d.b.h.

as the predictor. 

Stand age was estimated by counting rings on tree

stumps. Once adjusted for stump height (Omule and

Kozak 1989), combination of an age-d.b.h. relationship

with height-diameter curves allowed estimation of site

index for each treatment unit (Bruce 1981, Hann and

Scrivani 1987).

Information on average planted tree density at each of

the treatment units was obtained from post-harvest planting

records. The amount and composition of competing understory vegetation, used in simulating young stand growth,

was estimated from ground surveys on each subplot.

Simulations

Individual tree measurements were read into ORGANON,

an empirical growth and yield model developed for mixed

conifer forests of southwestern Oregon and Douglas-fir/

hemlock forests of western Oregon and Washington (Hann

et al. 1993). The southwest Oregon variant of ORGANON

(SWO) was used for all of the simulations. When necessary,

tree species present in the field plot but not supported in

the SWO variant were replaced with ecologically similar

species.

All treatment units were simulated for 100 years, or

twenty 5-year growth cycles. For the treatment units with

planted seedlings, the first 15 years of seedling growth

were simulated using the SYSTUM-1 young stand simulator (Ritchie et al.1993). Output from this model was then

merged with the tree lists of the measured overstory trees,

similarly grown 15 years. The merged tree lists were then

simulated another 85 years using ORGANON. On plots

with aggregated retention, separate runs were used for the

aggregates and the cut portion containing young trees; i.e.,

they were simulated as two separate stands with no competitive effects on each other.

Images of the projected stands were rendered with the

Envision Environmental Visualization System developed

by the USDA Forest Service, Pacific Northwestern Research

Station (http://forsys.cfr.washington.edu/envision.html).

Envision is a stand and landscape level visualization system

that incorporates a digital terrain model, thereby placing

stands in a geographic context and providing topographic

relief.

203

Figure 2—Retention levels and patterns of the six DEMO treatments.

Gray coloration represents retained trees; black denotes harvested areas.
To evaluate treatments for possible follow-up harvests,

alternative management scenarios were explored at Paradise

Hills, a Site IV, high elevation site in the Cascade Range.

Four scenarios were simulated: (1) BL—a baseline scenario,

involving no additional management activities; (2) UN—

understory management scenario, in which stands were

grown for 50 years and then 50 percent of the young trees

were removed; (3) UNOV—understory and overstory management scenario, in which the stands were thinned proportionally (thinned trees were distributed across the diameter

distribution) to a relative density of 35 whenever they reach

a relative density of 55 (Reineke 1933); and (4) TFB—

thinning-from-below scenario, in which thinned trees were

taken from the low end of the diameter distribution. Stands

were thinned from below to a relative density of 35 whenever they reached a relative density of 55.

RESULTS AND DISCUSSION

Figures 3 through 8 present stand-level and close-up

views of Capitol Forest treatment 15-percent dispersed

retention at years 0, 15, and 100 for the baseline management scenario (BL, no future treatment). At year 15, the

understory simulated with SYSTUM-1 is first available 

for incorporation into ORGANON and visualization with

Envision. Although this stand is two-storied at year 100, its

canopy appears closed. Any positive effect of the original

harvest on understory development can be expected to

reverse as both the overstory and understory grow. The rate

at which this occurs depends on the level and pattern of

retention, the productive capacity of the site, and the species

planted in the understory. Because visualizations can be

produced at each growth interval of the growth model, output from both, used in concert, make it possible to rapidly

assess canopy closure. Output from all treatments on all

blocks reinforces expectation: without further treatment,

closed canopies can be expected long before 100 years, even

where retaining only 15 percent of the original basal area.

Closed canopies within treatment units are unsuitable for

some forest biota but suitable for others. Therefore, structures can be maintained over time to meet habitat requirements of specific species targeted for management. In the

broader context, however, it is likely that a higher diversity

of taxa would be favored by keeping stand density at a

level that promotes ground vegetation (North et al. 1996,

Thomas et al. 1999). It is also important from a management perspective to consider the diversity of structures and

development stages across the landscape. Variable-retention

harvests distributed spatially and temporally across the

204

Figure 3—Capitol Forest treatment 15-percent dispersed, year 0, stand-level view.
205

Figure 4—Capitol Forest treatment 15-percent dispersed, year 0, close-up view.

Figure 5—Capitol Forest treatment 15-percent dispersed, year 15, stand-level view.
206

Figure 6—Capitol Forest, treatment 15-percent dispersed, year 15, close-up view.

Figure 7—Capitol Forest, treatment 15-percent dispersed, year 100, stand-level view.
landscape would provide a range in stand density and,

thereby, create a range in habitat conditions that any one

stand would not provide continuously. However, because

federal forest managers face difficulty in implementing

harvests, future harvests are unlikely to be distributed across

the landscape to compensate for many stands entering the

stem-exclusion stage of development (Oliver and Larsen

1996). Variable-retention treatments would also retain more

large trees, in contrast to the plantations produced over the

last several decades. One question remains however: Does

the presence of large trees, with a solid lower canopy and

diminishing understory, continue to provide sufficient habitat for organisms of interest? 

Output from the four management scenarios applied at

Paradise Hills is shown in figures 9 through 17. Basal area

responses indicate that the understory scenario (UN) accrues

more basal area than either the understory/overstory (UNOV)

or thin-from-below (TFB) scenarios, but less than the baseline (BL) (fig. 9). Furthermore, the UNOV and TFB scenarios have approximately similar basal areas throughout

the 100-year simulation. The differences between the baseline (BL) and reharvesting scenarios are also apparent visually, as are the differences among the reharvesting scenarios

themselves (figs. 10 through 17). For example, the density

of young trees in the TFB scenario (fig. 17) is noticeably

lower than density in the UNOV scenario (fig. 15).

Patterns in total volume production differ by variableretention treatment, management scenario, and cohort (fig.

18), largely because differences in overstory structure

affect growth and development of the understory. At a 40-

percent retention level, although overstory production for

the 100-year period is comparable between the aggregated

and dispersed retention, the well-distributed shade of dispersed trees limits growth and development of the understory cohort compared to uncut aggregates of the same

basal area. In contrast, at 15-percent retention, understory

production is roughly equivalent for both aggregated and

dispersed retention. However, with the significant spacing

given to overstory trees in the dispersed pattern, overstory

production is more than twice the amount observed in the

aggregated pattern.

In general, total volume production at Paradise Hills

decreased as harvest intensity increased from BL to UN to

UNOV and TFB. In addition to its effect on total volume

production, removing growing stock has a significant effect

on three-dimensional stand structure, an effect that is less

interpretable with bar charts and columns of numbers.

207

Figure 8—Capitol Forest, treatment 15-percent dispersed, year 100, close-up view.
Output from visualization software allows rapid assessment

of stand structural differences and facilitates communication about the effects of silvicultural treatments on structural

aspects relevant to both timber production and biodiversity.

CONCLUSIONS

Federal land management in the United States requires

trade-offs and balances among competing demands by 

various publics. This process is the quintessence of multiresource management and, hence, requires a multidisciplinary approach to developing silvicultural systems to achieve

complex objectives. Output from DEMO research, therefore, must be readily interpretable by many people and

groups with little or no silvicultural expertise. Coupling

growth models like SYSTUM-1 and ORGANON with a

visualization system like Envision can portray aspects of

stand structure that are relevant to all interested parties, and

thereby facilitate management planning by multidisciplinary

teams and multiple publics.

ACKNOWLEDGMENTS

This research is a component of the Demonstration of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of

Washington.

REFERENCES

Alaback, P.B. 1982. Dynamics of understory biomass in 

Sitka spruce-western hemlock forests of Southeast

Alaska. Ecology. 63: 1932-1948.

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Paradise Hills

BL

UN

UNOV

TFB

Figure 9—Stand basal area over time for four different management scenarios at Paradise Hills.
209

Figure 10—Paradise Hills, treatment 40-percent aggregate, baseline, year 100, stand-level view.

Figure 11—Paradise Hills, treatment 40-percent aggregate, baseline, year 100, close-up view.
210

Figure 12—Paradise Hills, treatment 40-percent aggregate, understory scenario, year 100, stand-level view.

Figure 13—Paradise Hills, treatment 40-percent aggregate, understory scenario, year 100, close-up view.
211

Figure 14—Paradise Hills, treatment 40-percent aggregate, understory/overstory scenario, year 100, stand-level view.

Figure 15—Paradise Hills, treatment 40-percent aggregate, understory/overstory scenario, year 100, close-up view.
212

Figure 16—Paradise Hills, treatment 40-percent aggregate, thinning-from-below scenario, year 100, stand-level view. 

Figure 17—Paradise Hills, treatment 40-percent aggregate, thinning-from-below scenario, year 100, close-up view.
Aubry, K.B.; Amaranthus, M.P.; Halpern, C.B.; White, 

J.D.; Woodard, B.L.; Peterson, C.E.; Lagoudakis, C.A.;

Horton, A.J. 1999. Evaluating the effects of varying 

levels and patterns of green-tree retention: experimental

design of the DEMO study. Northwest Science. 

73(special issue): 12-26. 

Bruce, D. 1981. Consistent height-growth and growth-rate 

estimates for remeasured plots. Forest Science. 

27: 711-725.

Christensen, N.L.; Bartuska, A.M.; Brown, J.H.; Carpenter, 

S.; D’Antonio, C.; Francis, R.; Franklin, J.F.; Macmahon,

J.A.; Noss, R.F.; Parsons, D.J.; Peterson, C.H.; Turner,

M.G.;Woodmansee, R.G. 1996. The report of the

Ecological Society of America Committee on the

Scientific Basis for Ecosystem Management. Ecological

Applications. 6: 665–691.

Franklin, J.F.; Norris, L.A.; Berg, D.R.; Smith, G.R.; 1999. 

The history of an experiment in regeneration harvest of

northwestern forest ecosystems. Northwest Science.

73(special issue): 3-11.

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in northwestern forest ecosystems: the Demonstration

of Ecosystem Management Options (DEMO) Study.

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Hann, D.W., Olsen, C.L., Hester, A.S. 1993. ORGANON 

user’s manual. Corvallis, OR: Department of Forest

Resources, Oregon State University. 113 p.

Hann, D.W.; Scrivani, J.A. 1987. Dominant-height-growth 

and site-index equations for Douglas-fir and ponderosa

pine in southwest Oregon. Res. Bul. 59. Corvallis, OR:

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36 p.

McGaughey, R.J. 1997. Visualizing forest stand dynamics 

using the stand visualization system. In: Proceedings 

of the 1997 ACSM/ASPRS Annual Convention and

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North, M.; Chen, J.; Smith, G.; Krakowiak, L.; Franklin, J. 

1996. Initial response of understory plant diversity and

overstory diameter growth to a green tree retention

harvest. Northwest Science. 70: 24-35. 

Oliver, C.D.; Larsen, B.C. 1996. Forest Stand Dynamics. 

New York: John Wiley and Sons. 521 p.

Omule, S.A.Y.; Kozak, A. 1989. Stump and breast height 

diameter tables for BC tree species. FRDA Rep. No.

062. Victoria, BC: For. Can. and BC Ministry of Forests.

213

Figure 18—Overstory and understory volume production, Paradise Hills, by treatment and management scenario.
Reineke, L.H. 1933. Perfecting a stand density index for 

even-aged forests. Journal of Agricultural Research. 

46: 627-638.

Ritchie, M.W.; Powers, R.F. 1993. User’s guide for 

SYSTUM-1 (Version 2.0): a simulator of growth trends

in young stands under management in California and

Oregon. Gen. Tech. Rep. PSW-GTR-147. Albany, CA:

U.S. Department of Agriculture, Forest Service, Pacific

Southwest Research Station. 45 p.

Thomas, J.W.; Forsman, E.D.; Lint, J.B.; Meslow, E.C.; 

Noon, B.R.; Verner, J. 1990. A conservation strategy 

for the northern spotted owl: report of the Interagency

Scientific Committee to Address the Conservation of

the northern spotted owl. Portland, OR: U.S. Department

of Agriculture, Forest Service; U.S. Department of the

Interior, Bureau of Land Management, Fish and

Wildlife Service, and National Park Service. 427 p.

Thomas, S.C.; Halpern, C.B.; Falk, D.A.; Liguori, D.A.; 

Austin, K.A. 1999. Plant diversity in managed forests:

understory responses to thinning and fertilization.

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Moriwaki, C.B. 1996. The Northwest Forest Plan: a

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214
1 Assistant Professor, Department of Forest Resources, Oregon State University, Corvallis, OR 97331, USA. Email: Hailemariam.Temesgen@oregonstate.edu

2 Stand Development Specialist, BC Ministry of Forests, Forest Practices Branch, Victoria, BC, Canada

3 Associate Professor, and 4 Professor, Department of Forest Sciences and Department of Forest Resources, Oregon State University; Corvallis, OR 97331, 

USA.

Balancing Ecosystem Values Proceedings, Modeling and Simulation

Effects of Different Levels of Canopy Tree Retention 

on Stocking and Yield of the Regeneration Cohort 

in the Southern Interior of British Columbia

Hailemariam Temesgen,1 Pat J. Martin,2 Douglas A. Maguire,3 and John C. Tappeiner4

BACKGROUND

Variable-retention harvesting (VRH), the practice of

leaving live trees after regeneration harvests has become a

tactic in ecosystem management. Retained trees carry over

many structural features of the old stand into the new one,

provide shelter for new regeneration (Franklin et al. 1997),

and are thought to help conserve late-seral species. In the

Pacific Northwest of the United States and Canada, most

forest management plans for public lands prescribe some

degree of VRH. Although many potential benefits of VRH

have been hypothesized, the actual effects of VRH on

future yield and stocking are unknown for most forest

types (Zenner et al. 1998). Recent studies, however, have

ABSTRACT

Variable retention has become a prominent silvicultural strategy for meeting multiple resource management objectives.

Under this strategy, retained trees contribute to the structural complexity of the subsequent stand, and provide habitat for

wildlife and shelter for regeneration and understory vegetation. Retained trees, however, affect the stocking and yield of the

young tree cohort to some degree. The effects of retained trees vary by the spatial arrangement of retention (group or dispersed), attributes of retained trees (type of species, condition, size and frequency), site, and other factors. 

Under a variable-retention strategy, accurate growth and yield predictions for the resulting two-tiered stands are required.

This paper outlines the effects of retained trees on understory tree development and compares various approaches that are

used to model and simulate the effects of different levels of retention on yield at rotation. Specific simulations were conducted to quantify the effects of retained trees on seedling stocking and future yield for pure lodgepole pine (Pinus contorta

Dougl. ex Loud.) and interior spruce (Picea engelmannii x glauca) stands in British Columbia. Compared to clearcut scenarios, retained trees reduced regeneration stocking by 0.3 to 6.5 percent on a stocked quadrat basis. The effects on the final

yield of the understory cohort ranged from -8 to -32 percent, depending on the level of retention (2 to 12 m2/ha). 

KEYWORDS: Stocking, growth and yield models, variable-retention harvesting, mean stocked quadrat, partial cutting,

understory development.

215

showed that VRH reduced the growth and future yield of

regenerating cohorts (Acker et al. 1998, Birch and Johnson

1992, Hansen et al. 1995, Long and Roberts 1992, Rose and

Muir 1997, Zenner et al. 1998). Variable-retention harvesting has also been shown to influence species composition

(Rose and Muir 1997).

The influence of retained trees varies by the pattern of

retention (group or dispersed), attributes of the retained trees

(i.e., species, condition, size and frequency), and other factors (e.g., site quality, windthrow, etc). Future growth and

yield is also affected by change in species composition. For

coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco),

Rose and Muir (1997) asserted that, compared to clearcuts,
the understories of stands with a relatively large number of

residual trees are dominated by higher relative densities of

shade tolerant tree species such as western hemlock (Tsuga

heterophylla (Raf.) Sarg.) and western redcedar (Thuja

plicata Donn) and lower relative density. The mix of species

that successfully regenerates will affect future growth, yield

and value. 

This paper (1) reviews the impacts of VRH on stocking

of regeneration and future yield of the understory cohort,

(2) reviews the methods used to quantify these impacts,

and (3) simulates the effect of overstory residual trees on

understory yield (volume at rotation) and stocking in dispersed VRH. Throughout this paper, impact on yield refers

to the impact of retained overstory trees on future yield of

understory cohorts grown to rotation age beneath.

IMPACTS OF VARIABLE-RETENTION

HARVESTING ON YIELD AND STOCKING 

Residual trees compete with understory cohorts for light,

water, and nutrients. This competition is proportional to (1)

area occupied by retained trees, and (2) size of retained trees,

vigor, and the level and duration of retention.

Rose and Muir (1997) estimated that half of the yield

reduction due to retained trees is due to their physical occupation of space. The remaining half results from other factors such as shading and competition for resources. Similarly,

in examining competition among retained trees, Canham et

al. (2004) concluded that crowding, which they defined as

“belowground competition and physical, aboveground inhibition of crown development,” had a larger influence on

retained trees radial growth than shading.

The impact of retained trees on understory yield is a

function of retained tree size and vigor (i.e., size of crown

and rate of crown expansion). Retained trees with large

crowns, and those that vigorously expand their crowns, more

strongly suppress understory tree growth (Birch and Johnson

1992) than those with smaller crowns and less vigorous

growth. As the amount of retention increases, understory

growth declines (Birch and Johnson 1992, Long and Roberts

1992, Hansen et al. 1995, Rose and Muir 1997, Acker et al.

1998). Retention that is short-lived, or removed after a brief

period, is less detrimental to understory tree growth.

Generally, impacts of retained trees on yield can be categorized in terms of effects on (1) mean annual increment

(MAI), (2) basal area and volume, (3) harvest value, (4)

individual tree attributes, and (5) stocking.

Mean Annual Increment 

Based on a field study, in the Willamette National Forest

in Oregon, Acker et al. (1998) found that mean annual

increment (MAI) of understory cohorts beneath retained

trees decreased with an increase of retained trees basal area,

and later estimated MAI of the lower canopy as a function

of initial residual basal area. For 10m2/ha residual tree basal

area, the authors predicted a 26-percent decline in the young

cohort’s MAI (with 95-percent confidence interval of -30

percent to -22 percent) in stands that ranged from 72 to 139

years old. 

In simulations with ORGANON, Birch and Johnson

(1992) found that compared to clear cutting, retention of 50

codominant overstory trees per hectare resulted in a 25.5

percent reduction in MAI of the young cohort. Leaving 20

to 50 trees per hectare also lengthened the time for a stand

to reach culmination of MAI by approximately 10 years. 

Basal Area and Volume 

Rose and Muir (1997) examined USDA Forest Service

inventory plot data from 132 stands (Cascade Range and

southwest area of Oregon) with and without residual trees

at different levels of retention. The authors found that

increased number and basal area of residual trees substantially reduced understory basal area. The relationship

between understory basal area and the density of retained

trees was sigmoidal. No significant decrease in understory

basal area was detected up to 15 retained trees per hectare.

At densities above 15 retained trees per hectare, understory

basal area declined. High densities of retained trees showed

a decreasing marginal effect on understory basal area. Acker

et al. (1998), Hansen et al. (1995), and Birch and Johnson

(1992) noted yield losses at levels as low as 5 retained

trees per hectare.

In a paired plot study, Acker et al. (1998) examined 14

stands in the Willamette National Forest (Oregon) and estimated the effect of retained trees on forest structure and

yield and found that basal area and volume per hectare

decreased with an increase in residual basal area. At a

residual leave tree basal area of 10m2/ha, volume in the

younger cohort after 100 years was reduced by 23 percent. 

Analyzing data from Acker et al. (1998), Zenner et al.

(1998) found that leaving 5 to 50 trees per hectare (5 to 60

percent of total stand volume) reduced total volume by 22

to 45 percent, compared to zero retention. Using a paired

plot study in Barenthoren forests in Germany, Assmann

(1970) showed that the presence of 20 mature residual pine

trees per hectare reduced the understory Scots pine (Pinus

216
sylvestris L.) yield by 20 percent when compared to singlestoried stands with no retained trees. 

Andreassen (1994) compared the yield of 16 partially cut

Norway spruce (Picea abies) stands (established between

1921 and 1939) to their respective even-aged yield tables

and found a 20-percent yield reduction compared to evenaged stands. However, the accuracy of this reduction is

dependent upon the exactness of the yield curves. Using

the ZELIG forest-level model, Hansen et al. (1995) examined nine retention levels (0, 5, 10, 15, 20, 30, 50, 100, and

150 trees per hectare) at four rotations (40, 80, 120, and

240 years) in a hemlock-fir-redcedar forest in the Oregon

Cascade Range. The results of this study indicated that, at a

120-years rotation, leaving 5 trees per hectare reduced final

basal area by 18.5 percent and leaving 30 trees per hectare

reduced basal area by 38.6 percent, when compared to basal

area in stands regenerated after clear cutting (table 5 in

Hansen et al. 1995). 

In their simulation of the development of a well-stocked

80-year Douglas-fir stand on a median (site index of 33 m)

site, Birch and Johnson (1992) mainly ascribed the high

merchantable volume reduction in VRH to the influence of

retained trees on the growth of the understory. In this study,

they accounted for the blow down of retained trees. Based

on the impact of a 30-year storm event, the authors assumed

10-percent blow down of retained trees over a rotation. 

Harvest Value

In their comprehensive analysis of alternative silvicultural systems, Hansen et al. (1995) concluded that retention

level and rotation age strongly influenced ecological and

economic responses in western Oregon forests. Hansen et

al. (1995) noted that future yield decreased significantly

with increasing retention level and rotation age, with a

notable threshold between retention levels of 0 and 5 trees

per hectare. The authors asserted, however, that the decrease

in the net wood products value was not directly proportional

to level of retention due to the high value of logs from

retained trees (assuming the retained trees are harvested 

at the end of the rotation). 

Individual Tree Attributes

On national forest land in Oregon, Isaac (1956) reported

that height growth of Douglas-fir saplings was reduced

when the number of retained trees was as low as 26 trees

per hectare. This finding was supported by Hoyer’s (1991)

findings that indicated significant height growth reduction

even under only one retained tree. 

Hansen et al. (1995) examined planted Douglas-fir near

the Oregon coast at 20 m and greater distance from a 45-m

tall southern intact stand boundary. After 10 to 11 years of

growth, they found a 20-percent reduction in height and

diameter at 20 m but no decrease at 40 m compared to

growth in the open. Using data from 19 stands in western

Washington, Hoyer (1991) found that a reduction in height

growth was greatest immediately adjacent to an overstory

tree, and decreased with distance from the tree, until at 20 m

away, the reduction was no longer significant. Based on

these findings, Acker et al. (1998) assumed that the effects

of a residual tree on the young cohort were minimal at and

beyond 18.3 m.

Wampler (1993) investigated the relationship between

retained trees density and understory height growth of

Douglas-fir trees in the Gifford Pinchot and Mount BakerSnoqualmie National Forests. The author found that

1) The relationship between retained trees density and

understory tree height growth changed over time;

2) On average, height growth was reduced by 15 percent,

when compared to the clear cut scenario; 

3) A positive correlation between height to diameter ratios

(a measure of stability for a tree) and retained trees density existed in four of the seven stands considered in the

study; and

4) Noticeable height growth reduction occurred even under

few retained trees. 

Retained trees shade seedlings and saplings growing

near them. The growth rates of understory interior spruce

(Picea engelmannii x glauca) and lodgepole pine (Pinus

contorta Dougl. ex Loud.) have been related to understory

light levels in many studies. Coates and Burton (1999)

examined the height and radial growth of planted lodgepole

pine and interior spruce growing under a wide range of

light levels in a partial cutting experiment. They found that

at 50 percent of open-sky light, lodgepole pine achieved 60

percent of height and 50 percent of diameter growth possible under full light. At 50 percent of full light, interior spruce

achieved 57 percent of height and 54 percent of diameter

growth observed under open-sky conditions. Over a number

of climatic regions in British Columbia, Wright et al. (1998)

studied the relationship of sapling height and radial growth

to light level. In the western sub-boreal region at 50 percent

light, lodgepole pine achieved 34 percent of the height

increment and 24 percent of the radial increment observed

at 100 percent light. At 50 percent light, interior spruce

achieved 71 percent of height and 51 percent of radial growth

potential. Shading also impacts other understory pine and

217
spruce tree attributes such as live crown ratio, leader over

lateral length ratio, number of branches per whorl, and root

over shoot ratio (Messier et al. 1999, Williams et al. 1999).

Though understory tree growth correlates well to understory light levels, retained trees may also reduce seedling

growth by competing for soil moisture and nutrients or

reducing soil temperature (Lajzerowicz et al. 2004). 

Stocking

Though the long-term impacts of retained trees on

understory tree height and diameter growth are negative,

retention may increase understory tree stocking over the

short-term (Kobe and Coates 1996). Seed rain, germination

and short-term survival may increase in the presence of

retained trees. However, over the longer term at higher 

levels of retention, seedling and sapling mortality rates

increase (Kobe and Coates 1996). 

METHODS TO QUANTIFY IMPACTS OF

VARIABLE-RETENTION HARVESTING

Methods to quantify the impacts of different levels and

patterns of retention on future yield include retrospective

studies and model extrapolation and simulation techniques.

Retrospective studies have been used to estimate the effects

of overstory residual trees on regeneration yield (Acker et

al. 1998, Assman 1970, Hansen et al. 1995, Rose and Muir

1997, Zenner et al. 1995). In these studies, paired plots (one

with and the other without residual trees) are placed as close

as possible to compare understory yield trajectories. 

Assmann (1970: 408) noted that trees retained at the

stand boundary might have lower effect on the growth of a

young cohort than residual trees further in the stand. Other

studies that reached similar conclusions include Hoyer (1991,

1993) and Wampler (1993). Several studies have assessed

the influence of stand microclimate and edges adjacent to

residual trees (e.g., Carter and Klinka 1992, Chen et al.

1993). However, most of these studies did not quantify the

impact of residual trees on growth and yield of the future

forest. 

Most of the retrospective studies (e.g., paired plot comparisons or comparison to an existing yield curve) have

little information on past stand history, making yield impact

estimates inconclusive. Recognizing this, Acker et al. (1998)

asserted that even though the results and comparisons made

using retrospective studies are indicative only, these studies

provide information quickly, facilitate understanding of

stand dynamics, and are a useful complement to long-term

field experiments. 

Model Extrapolation and Simulation Techniques

The Prognosis (Long and Roberts 1992) and ORGANON

(Birch and Johnson 1992) growth and yield models have

been used to quantify the yield impacts of retained trees.

Other simulation techniques have also been used (Hansen

et al. 1995). Using a variant of the Prognosis model, Long

and Roberts (1992) simulated stand development under

various levels of Douglas-fir retention. Retention of 12 to

86 trees per hectare for 100 years produced a 24- to 54-

percent reduction in understory volume production.

Using the growth and yield model ORGANON, Birch

and Johnson (1992) simulated the impact of leaving 5 to 

50 Douglas-fir trees (from the upper half of the diameter

distribution) per hectare in clumped and scattered arrangements for 60- and 90-year rotations. The retention of 5 to

50 trees per hectare (approximately 2 percent and 16 percent of initial stand volume, respectively) showed a 5 to 37

percent reduction in understory merchantable volume on a

60-year rotation, compared to no overstory retention (fig. 1,

in Birch and Johnson 1992). 

Our review of the literature suggests that, given the

importance of the issue, information on effects of retained

trees on yield and stocking remains inadequate. Few longterm data exist to quantify the impacts of retained trees on

yield and stocking. Resource managers have no direct way

of estimating the impact of retained trees on yield and future

stand structure. In light of this, interim estimates quantifying

the impacts of retained trees on yield and stocking are paramount. In this study, regeneration survey simulation was

combined with stand-growth simulation to quantify the

impacts of retained trees on yield and stocking of pure pine

and spruce stands in the interior of British Columbia.

METHODS

Stand Survey and Simulation 

To assess the effects of VRH on stocking of regeneration

and yield of the understory, the Tree and Stand Simulator

(TASS) (Mitchell 1975) was used to simulate the growth 

of 268 pure pine and interior spruce stands with differing

establishment densities (both planted and natural), spatial

distributions, and levels of retention (table 1). 

TASS is an individual tree distance-dependent growth

model that generates, spatial, stem-mapped data (Mitchell

1975), and it is widely used for timber supply analysis and

adjusting the yield impacts of retained trees.

218
Simulations were used to study the effect of retained

trees on regeneration stocking after 10 years of stand development and understory yield after 80 years of growth.

Simulations were done for a 3-ha area. Regeneration surveys were simulated on the stem maps extracted from the

stand growth simulator 10 years after harvest. In each stand,

sample plots (50 m2, 3.99 m radius) were established on

randomly oriented 25-m grids resulting in approximately

48 plots for each simulated survey (a 25-m grid provides

16 plots per hectare). For each of the 268 simulated stands,

30 independent surveys were simulated, resulting in 8,040

simulated surveys. 

Each 0.005-hectare circular plot was split into quarters

(quadrants) along the north-south and east-west axes. The

species and height of each tree in each quadrant was recorded.

A quadrant was considered stocked if it contained at least

one live tree. For each plot, the number of stocked quadrants was counted. For each survey, mean stocked quadrant

(MSQ) was calculated (J.S. Thrower and Assoc. 2002,

Martin et al. 2002) and later was compared to merchantable

volume 80 years after harvest. In addition, relationships

and associations between MSQ and merchantable volume

80 years after harvest were examined. 

RESULTS AND DISCUSSION

Data Summary

In this study, the distributions of simulated stands by

seedling establishment density and basal area of retained

219

Figure 1—Merchantable volume of the understory stand 80 years after harvest over establishment density under different

levels of retention (2 to 12+m2/ha) of lodgepole pine (a) and spruce (b) trees.

Table 1—Attributes in the matrix of TASSa runs used to examine the impact of

retained trees on understory stocking and future yield in pure pine and spruce

stands

Factor Levels

Planting density (no./ha) 0, 600, 1200

Natural density 0, 600, 1200, 3000, 4000

No. of retained green trees/ha (retained trees) 0, 12, 48, 96, and 144 trees/ha

Spatial distribution of naturals and retained trees Random

Site index 20 m

a Tree and Stand Simulator (TASS) is an individual tree, distance-dependent growth model developed by 

Mitchell (1975).

Note: All possible combinations of the factors listed in table 1 were not simulated because of limitations 

with the current TASS version (Polsson 2003). However, the simulations above, done by Ken Polsson,

BC Ministry of Forests, covered a wide range of established densities, basal area, and number of retained

trees.
trees were similar for both lodgepole pine and spruce

stands. A quarter of the simulated stands had establishment

density of 1000 to 1750 seedlings per hectare. Similarly,

for both species, 25 percent of the simulated stands were

established with more than 3000 seedlings per hectare

(table 2).

The average diameter at breast height (d.b.h.) and height

of the retained trees were 34.2 cm and 22.9 m, respectively,

for pine and 38.0 cm and 28.6 m, respectively, for spruce

stands (table 2). Even though the retained trees did not differ much in size, the simulated stands covered a wide range

of crown closure (3 to 43 percent) at the start of the simulation. At the time of survey simulation (10 years post-harvest), regeneration establishment density for the simulated

stands ranged from 274 to 5063 trees per hectare. After 80

years, the simulated stands covered a wide range of conditions. For example, crown closure ranged from 54 to 100

percent, basal area ranged from 9.8 to 58.3 m2/ha, and

merchantable volume ranged from 67.0 to 474.0 m3/ha

(table 2). 

For lodgepole pine, the average crown diameter of

retained trees was 5.7 m (table 2), representing 25.5 m2 in

crown projection area. Hence a density of 12 retained trees

per hectare represents 3 percent of the total area and 96

retained trees represents 24.5 percent of the total area.

Negative correlations were observed between average crown

width of retained trees and merchantable volume 80 years

after harvest. 

For the regeneration layer, there was strong relationship

between establishment density and merchantable volume

80 years after harvest (fig. 1). Under different levels of

retention, the future merchantable volume of the younger

cohort increased rapidly with an increase of establishment

density up to 1500 seedlings per hectare.

For both pine and spruce stands, the average number 

of mean stocked quadrants 10 years post-harvest decreased

with an increase of number and basal area of retained trees.

As expected, MSQ increased with an increase in regeneration density (table 3). The variability among estimated MSQ

220

Table 2—Attributes of simulated test population (stands) 10 and 80 years after harvest for pure lodgepole pine 

and spruce stands

Lodgepole pine stands, n=134 Spruce stands, n=134

Scenario Attribute Min. Mean Max. Std Min. Mean Max. Std

At start Number of trees/ha 0 61 144 54 0 61 144 54

of simulation Crown closure (percent) 3.0 20.3 38.0 12.6 4.0 22.2 43.0 13.8

(attributes of retained Basal area (m2/ha) 1.0 7.1 14.0 4.8 1.3 9.1 18.3 6.1

trees (RT)) Merch. volume (m3/ha) 8.0 55.8 110.0 37.0 12.0 87.4 176.0 58.1

Average height (m) 22.2 22.9 23.6 0.2 27.8 28.6 30.0 0.3

Average diameter (cm) 32.6 34.2 36.3 0.5 35.3 38.0 40.6 0.8

Average crown width (m) 5.5 5.7 6.1 0.1 5.7 5.9 6.5 0.2

Density of regen (tree/ha) 274 1765 5063 1375 260 2032 5660 1450

After 80 years Number of trees/ha 304 992 1382 298 283 894 1350 272

(attributes of RT Crown closure (percent) 54.0 97.1 100.0 8.5 64.0 98.0 100.0 6.3

and regeneration Basal area (m2/ha) 9.8 35.9 48.8 8.7 11.7 40.3 58.3 11.2

cohort) Merch. volume (m3/ha) 67.0 259.6 353.0 67.2 102.0 335.2 474.0 94.0

Average height (m) 17.2 32.8 25.9 0.5 19.4 27.6 35.0 1.1

Average diameter (cm) 18.4 29.6 39.2 2.6 19.7 33.9 46.5 3.3

Average crown width (m) 2.5 3.2 4.6 0.6 2.4 3.2 4.9 0.7

Basal area of retained trees 

(m2/ha) 0.0 6.7 16.3 6.0 0.0 9.2 22.7 8.2

Merch. volume of retained

trees (m3/ha) 0.0 57.1 139.0 50.9 0.0 97.9 242.0 87.0
values increased with an increase in the number and basal

area of retained trees and decreased with an increase in

regeneration density (table 3).

For a given density class, MSQ decreased as basal area

of the retained trees increased. Increasing the establishment

density from 750 to 1500 seedlings per hectare increased

the average mean number of stocked quadrants from 3.48

to 3.80 and from 3.41 to 3.69 for pine and spruce stands,

respectively. An increase of retained trees from 12 to 48

retained trees per hectare decreased MSQ from 3.58 to 3.57

and from 3.66 to 3.44 in pine and spruce stands, respectively (table 3). 

For each level of retention, there was strong and consistent evidence that understory merchantable volume 80 years

after harvest increased with MSQ (figs. 2 and 3), reflecting

the effects of retained trees on both stocking and growth of

the understory component. The maximum merchantable

volume achieved decreased with an increase in retained

basal area (figs. 2 and 3). 

The difference between predicted merchantable volume

with and without retention increased with an increase in

retained basal area. When basal area of the retained trees

was less than 2 m2/ha, however, most of the observed differences included zero within their 95-percent confidence

intervals. There was strong association between the observed

differences in merchantable volume and retained basal

area, with a correlation coefficient of -0.817 and -0.90 for

pure lodgepole pine and spruce stands, respectively.

SUMMARY

Various methods are used to examine the impacts of

retained trees on the growth of seedlings established around

them. Over the long term, retained trees reduce understory

tree height and diameter growth and increase mortality,

resulting in reduced basal area per unit and reduced volume

production by the young cohort. 

Simulation results from this study demonstrate that the

impacts of retained trees differ by species, retention level,

and understory density for pure lodgepole pine and interior

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Table 3—Number of stands, minimum (min), mean, maximum (max), and standard deviation (Std) of

mean number of stocked quadrants by number and basal area of retained trees, and regeneration density for pure pine and spruce stands. Mean number of stocked quadrants values were obtained from 

30 simulated surveys 10 years after harvest.

Pure pine Pure spruce

No. of Mean no. of stocked quadrant Mean no. of stocked quadrant

retained No. of No of

trees/ha stands Min Mean Max Std stands Min Mean Max Std

0 26 2.16 3.68 3.89 0.39 26 2.09 3.68 3.87 0.40

12 27 1.06 3.58 3.89 0.63 27 2.12 3.66 3.88 0.41

48 27 1.20 3.57 3.90 0.61 27 1.00 3.44 3.90 0.81

96 27 1.38 3.55 3.87 0.58 27 1.00 3.47 3.85 0.64

144 27 1.42 3.52 3.86 0.55 27 1.00 3.41 3.84 0.62

Basal area class (m2/ha) Basal area class (m2/ha)

2 53 1.06 3.63 3.89 0.52 53 2.09 3.67 3.88 0.40

6 27 1.20 3.57 3.90 0.61 27 1.00 3.44 3.90 0.81

10 27 1.38 3.55 3.87 0.58 25 1.00 3.45 3.85 0.66

12+ 27 1.42 3.52 3.86 0.55 29 1.00 3.44 3.84 0.61

Density class (no. reg/ha) Density class (no. reg/ha)

250 18 1.06 2.47 3.36 0.77 18 1.00 2.41 3.28 0.80

750 24 2.86 3.48 3.82 0.30 26 2.77 3.41 3.72 0.29

1500 36 3.58 3.80 3.88 0.07 34 1.00 3.69 3.87 0.48

2500 22 3.72 3.84 3.90 0.04 23 3.70 3.81 3.86 0.04

3500+ 34 3.80 3.85 3.89 0.02 33 3.78 3.84 3.90 0.03
spruce stands. Compared to clearcut scenarios, retained

trees reduced regeneration stocking by 0.27 to 6.52 percent

on a stocked quadrat basis. The effects on the future yield

of the understory cohort ranged from -8 to -32 percent,

depending on the level of retention (2 to 12 m2/ha). 

The greater the vertical complexity of the stand, the more

important it will be to apply individual tree models for simulating specific stands. Likewise, the greater the horizontal

complexity of the stand, the more important it will be to

project future development with distance-dependent models.

The general relationships that we have demonstrated between

residual basal area, seedling stocking, and future understory

yield provide useful insight into some of the impacts of

retained overstory trees. 

ACKNOWLEDGMENTS

We thank Valerie LeMay, Peter Marshall, Steve Mitchell,

Ken Day, (all at Faculty of Forestry, at the University of

British Columbia), Bill Beese, (Weyerhaeuser Ltd. Canada),

Kim Iles, (Iles & Assoc.), Rick Dawson, (Ministry of

Forests, Cariboo Forest Region), and Jim Goudie, (Ministry

of Forests, Research Branch) for their insights and advice

on this project. This project was funded by Forest Innovation

BC (and administered by Riverside Forests Products Ltd),

and Department of Forest Resources at Oregon State

University.

222

Figure 2—Merchantable volume 80 years after harvest versus mean stocked quadrants for the young cohort of pure 

lodgepole pine stands under four levels of retention. Mean number of stocked quadrants values were obtained from 

surveys completed 10 years after harvest.
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Andreassen, K. 1994. Development and yield in selection 

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Assmann, E. 1970. The principles of forest yield studies. 

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223

Figure 3—Merchantable volume 80 years after harvest versus mean stocked quadrants for the young cohort of pure

interior spruce stands under four levels of retention. Mean number of stocked quadrants values were obtained from

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continue
BIODIVERSITY
Photo by Tom Iraci
1 USDA Forest Service, Pacific Northwest Research Station, Olympia, WA 98512, USA. Email: acarey@fs.fed.us 

Balancing Ecosystem Values Proceedings, Biodiversity

Active Intentional Management (AIM) 

for Biodiversity and Other Forest Values

Andrew B. Carey1

INTRODUCTION

Societies demand much of their forests. When people

were scarce and primeval forest abundant, forests were

impediments to progress. Now people are abundant, forests

are reduced in area, and most temperate forests are second

growth. As the pace of social evolution quickens, many

look to naturalistic forests for wholeness, stability, and 

permanence. Millenarian forests of the Pacific Northwest,

USA, especially provide a “cathedral” that is spiritually

evocative. Forested lands, nevertheless, continue to be 

converted to other uses even as the value of forests as

providers of ecological services such as green space, clean

water, clear air, and carbon sequestration are increasingly

apparent. Furthermore, as citizens in democracies question

governments about intragenerational social justice for people, desire for intergenerational equity (leaving a good world

to future generations) and ecological justice for other species

ABSTRACT

Comparisons of natural and managed forests suggest that neither single-species management nor conventional forestry is

likely to successfully meet meeting broad and diverse conservation goals. Biocomplexity is important to ecosystem function

and capacity to produce useful goods and services; biocomplexity includes much more than trees of different sizes, species

diversity, and individual habitat elements. Managing multiple processes of forest development, not just providing selected

structures, is necessary to restore biocomplexity and ecosystem function. Experiments in inducing heterogeneity into secondgrowth forest canopies not only support the importance of biocomplexity to various biotic communities including soil organisms, vascular plants, fungi, birds, small mammals, and vertebrate predators but also suggest management can promote

biocomplexity. At the landscape scale, strategies emphasizing reserves and riparian corridors that do not take into account

ecological restoration of second-growth forest ecosystems and degraded streams may be self-fulfilling prophecies of forest

fragmentation and landscape dysfunction. Restoring landscape function entails restoring function to second-growth forest.

Intentional management can reduce the need for wide riparian buffers, produce landscapes dominated by late-seral stages

that are hospitable to wildlife associated with old-growth forests, provide a sustained yield of forest products, and contribute

to economic, social, and environmental sustainability.

KEYWORDS: Biodiversity, northern spotted owl, northern flying squirrel, trurrles, keystone complex, mosaics.

227

flourish concomitantly (Ray 1996). Old-growth forests are

mostly in reserves and parks, distant from people, and insufficient to provide various values in the amounts desired by

people. Young forests with old-forest legacies may sustain

biodiversity, and likely will develop high biocomplexity

and “naturalness” if left untouched. Biocomplexity does

much to promote human experiences of wildness, naturalness, and spirituality. But much second growth, even within

reserves, is low in ecological capacity and may not develop

into biologically complex forest capable of providing diverse

values. Industrial “fiber farms” will not provide most values people seek—orderly plantations suggest human domination over nature devoid of wildness and naturalness with

biodiversity intentionally suppressed.

The challenge we face is how to actively and intentionally manage (AIM) extra-reserve forests to provide the

diverse values society demands. Comparisons of natural
and managed forests show single-purpose management is

unlikely to provide full societal value because complexity

is more important than single habitat elements to both biodiversity and capacity to produce various goods and services

(Carey 2003a). Zoning for single purposes accentuates

fragmentation and can result in cumulative effects that negatively impact soil, hydrologic processes, aquatic habitats,

population viability of rare species, native species through

invasion by exotic species, and ability to manage efficaciously and efficiently. Restoring landscape function entails

restoring biocomplexity to second-growth forests over broad

areas and managing ecosystem and landscape processes

and dynamics rather than static ecosystem and landscape

structures (Carey 2003b). AIMing for multiple values is

guided by empirical, experimental, and modeling data

(Carey et al. 1999b). AIM also requires some reference

condition by which to judge success. I use the ancient

forests of the Pacific Northwest, which by their very persistence over 250-1,000 years demonstrate high biodiversity

and robustness in the face of change. In particular, I use the

arboreal-rodents keystone complex and forest-floor smallmammal community to set benchmarks and measure 

success of management.

The arboreal-rodent keystone complex of the northern

spotted owl (Strix occidentalis caurina), northern flying

squirrel (Glaucomys sabrinus), ectomycorrhizal fungi, and

Douglas- fir (Pseudotsuga menziesii (Mirb.) Franco var.

menziesii) provides a heuristic framework for analysis. The

spotted owl is threatened with extinction due to loss of old

(long-lived, resilient, persistent), naturally complex forests.

The flying squirrel is the primary prey of the owl. Truffles

(sporocarps of ectomycorrhizal fungi) are the primary food

of the squirrel. The squirrel disperses truffle spores and

associated microorganisms throughout the forest (Li et al.

1986). Mycorrhizal fungi enhance the ability of Douglas-fir

(and other trees) to absorb water and nutrients from the soil

and receive carbohydrates in return. The fungi move photosynthetic carbohydrates from trees to the mycorrhizosphere,

a vast array of microbes, insects, nematodes, bacteria, and

other soil organisms. If one expands consideration to the

arboreal rodent group, then a broader food web is accounted

for. For example, I measured the total and relative biomass

(percent due to each species) of three squirrels, the northern

flying squirrel, Douglas’ squirrel (Tamiasciurus douglasii),

and Townsend’s chipmunk (Tamias townsendii), and compared them to the simultaneously high abundances of the

three species in old-growth forest. Biomass of this species

group is informative because it represents the energy available to medium-sized carnivores and the energy available

to consumers in terms of the reproductive output of the forest ecosystem (flowers, seeds, berries, nuts, mushrooms,

and truffles). The arboreal rodents are the major prey for most

of the medium-sized predators in the forests (including

hawks, owls, weasels, felids, canids). Although diets of the

three species overlap, the flying squirrel is a truffle and

mushroom specialist, the Douglas’ squirrel a conifer seed

specialist, and Townsend’s chipmunk is a fruit generalist,

feeding on conifers seeds, seeds and nuts of deciduous

trees, berries of shrubs, and truffles (but relegated to areas

of high shrub cover). Thus, not only does the combined

biomass of these three species reflect fruiting by plants and

fungi, it also determines the carrying capacity of the forest

ecosystem for a diverse assemblage of the medium-sized

predators. Thus, the combined biomass is a measure of

ecological productivity and can be measured at the local

(stand) scale (Carey et al. 1999b). If one moves up an additional level in the forest ecosystem, for example to vertebrate predators, populations often respond to landscape

character or regional variation, like the spotted owl (Carey

et al. 1992) and cannot be used to evaluate management at

small scales. 

Most would agree that the forest floor (litter, humus,

and soil) functions as the foundation for sustainability of

forest ecosystems. Biological activity in the forest floor

depends on a variety of invertebrates that are important in

nutrient cycling. Forest-floor invertebrates are abundant in

both species and individuals, with species often unknown

or poorly described. Still, changes in the structure of biotic

communities in response to forest management generally

are more informative than changes in the abundances of

single species (Carey et al. 1999a, b; Carey and Harrington

2001). Thus, I stepped up one level in the forest ecosystem

to measure the most tractable group of organisms dependent on forest-floor diversity and function. I measured the

biotic integrity (composition and relative abundance of

species compared to old forests) of the forest-floor, small

mammal community that includes granivores, herbivores,

fungivores, and insectivores, but which is particularly

diverse in insectivores in Pacific Northwest forests (Carey

and Harrington 2001). In various studies, I incorporated

other biotic communities to form expanded complexes that

are more comprehensive in evaluating forest ecosystem

function than any single species, biotic community, or

trophic pathway. 

METHODS

Three types of studies sharpen active, intentional management: comparative or cross-sectional studies, experimental studies, and computer simulations. Initially crosssectional studies focused on comparing natural forests of

different ages—young (40 to 80 years), mature (80 to 200

228
years), and old (>200 years). In the 1980s, an interagency

multi-university effort compared biotic communities in old

growth, mature, and naturally young studies in multiple

physiographic provinces in northern California, and western

Oregon and Washington. Communities included vascular

plants, belowground fungi, reptiles, amphibians, birds and

mammals (summarized in Ruggiero et al. 1991). Then, I

expanded these studies to compare managed young, naturally young, and naturally old stands. Similar geographical

replication was used to study spotted owl habitat use, owl

demography, owl prey bases, and associated food webs in

natural and managed forests (summarized in Carey et al.

1992, 1999a; Carey and Harrington 2001; Forsman et al.

1993). 

In 1991, drawing from comparative studies, I implemented two experiments in accelerating development of

biocomplexity (high plants species diversity, spatial heterogeneity in the understory density and composition, and

diversity in the vertical distribution of foliage) by inducing

heterogeneity into second-growth forest canopies similar 

to that in old growth (fig. 1). Maps of natural mosaics had

revealed 0.1-0.5-ha patches with a 2:1 ratio of closed to

open canopy (Carey et al. 1999a). In the Puget Trough of

Washington (summarized in Carey 2003a, Schowalter et al.

2003) and, later, across the Olympic Peninsula (Carey and

Harrington 2001), I used variable-density thinning (VDT)

to create canopy mosaics in a wide variety of secondgrowth stands (including previously intensively managed

with conventional thinning, passively managed with legacies

from old growth, and extensively managed without legacies,

with or without thinning). I hypothesized that removing

subordinate and codominant trees would make light, water,

nutrients, and space available in various amounts to other

vegetation though space in the thinned stand. Effects would

extend beyond the altered patches of canopy because of

low sun angles. Thus, fine-scale canopy heterogeneity would

create an even more diverse mosaic of environmental conditions and numerous patch types in the understory (Canham

et al.1990). For convenience, I will refer to stands that were

subjected to VDT as mosaics; stands that originated after

clearcutting but that still retained legacies from old growth,

such as scattered large live trees, large dead trees, tall stumps

of harvested large trees, and large fallen trees and associated

biota as legacy stands; stands that had been managed intensively for timber with multiple conventional thinnings as

timber stands; and to the common, extensive second growth

as second growth.

Finally, in 1994, I led at a team that modeled alternative

approaches to landscape management, including AIM to

conserve biodiversity (Carey et al. 1999b, Carey 2003b).

Three final scenarios were chosen for full evaluation: protection with no manipulation; management to maximize

net present value of wood production; and AIM for a multiplicity of values. Alternatives were evaluated on ability to

maintain spotted owls (a threatened species), capacity to

support vertebrate diversity (based on 130 species), relative

forest-floor function (biotic integrity of the small mammal

community), ecological productivity (biomass of arboreal

rodents and numbers of deer and elk), timber productivity,

and timber revenues.

229

Figure 1—Recreating spatial heterogeneity characteristic of old forests in

second-growth forest canopies with variable-density thinning: (A) densities of trees >50 cm at 1.5 m above ground in a 280-year-old Pseudotsuga

menziesii forest, shading (light to dark) represents densities from 3 to 45

trees/ha, based on 225 sampling points (from Carey et al. 1999b); (B) relative densities of P. menziesii >20 cm at 1.5 m following variable-density

thinning of a 56-year-old, second-growth stand; shading (light to dark)

represents relative density classes of <3.25, 3.25-4.75, 4.75-6.75, and

>6.75 (from Carey et al. 1999c).
RESULTS

Comparative Studies

In the Pacific Northwest, natural forests and contemporary managed forests differ in structure, composition, and

function (Carey et al. 1999a, Carey and Harrington 2001,

Franklin et al. 2002). In natural forests, many ecosystem

elements are patchily distributed. These elements include

live trees from the preceding stand, large fallen trees, trees

with cavities used for denning and nesting, berry-bearing

shrubs, deciduous trees, shade-tolerant trees in the midstory,

forbs, mosses, and fruiting bodies (truffles) of ectomycorrhizal fungi, among others. Groups of these elements may

be correlated in their occurrences due to topographic effects

or canopy gap formation and, thus, form distinct patches.

Diverse patches, arrayed in fine scale, contribute to emergent properties, such as simultaneously high abundances of

potentially competing species that do not occur together in

high abundances in large, homogeneous patches. The scale

of variation in arrangement that contributes to this synergy

is about 0.1 to 0.5 ha, or 80 to 100 m (Canham et al. 1990,

Carey et al. 1999a). Biotic legacies from preceding forest,

propagules from adjacent stands, forest structuring processes,

and development of spatial heterogeneity interact to produce both overall compositional diversity and patch diversity (habitat breadth) (Carey et al. 1999a, Franklin et al.

2000). In contrast, stand tending focused on timber production, particularly even-age management, purposefully reduces

spatial heterogeneity and compositional diversity (Carey

2003a, Carey and Harrington 2001). Consequently, the

response of species to changes in abundances of particular

elements of their habitat varies from place to place in managed forests, in relation to the relative abundances of other

ecosystem elements. The diversity and structure (biotic

integrity) of vertebrate communities, however, varies consistently in response to complexity of vegetation structure

and absence of various compositional elements because

spatial heterogeneity and compositional diversity (together,

biocomplexity) in plant and fungal communities are prerequisite to preinteractive niche diversification, animal community diversity, and the ability of ecosystems to resist or

recover from disturbance (Carey et al. 1999a, Tilman 1999).

Forest management can promote biocomplexity (Carey et

al. 1999a, b; Lindenmayer and Franklin 2002). Retention

of legacies of individual live trees, dead trees, coarse woody

debris, or even patches of forest can be used with even-age

or uneven-age management systems (Franklin et al. 2000).

Variable-retention harvest systems transcend traditional

silvicultural conventions (Lindenmayer and Franklin 2002).

Thinning influences all structuring processes, including

decadence and development of spatial heterogeneity. Thinning with underplanting restores tree species diversity and

accelerates canopy stratification and understory development (Thysell and Carey 2001). Retaining decadent trees,

wounding trees, and inoculating trees with top-rot fungi

promote decadence essential to ecosystem development

(Carey et al. 1999a). 

Experimental Results

Fungi—Historical management seemingly influenced

the structure of soil food webs in experimental secondgrowth plots, but all retained fungi-dominated soils. Fungal

to bacterial biomass ratios were higher in legacy than in

timber stands for total biomass and for active biomass, however. Fungal mats covered two-thirds of the forest floor in

legacy stands but only one quarter in timber stands. Compared

to controls, VDT had no effect on total biomass ratios, but

increased active biomass ratios in both timber mosaics and

legacy mosaics. Total fungal biomass remained unchanged

in timber mosaics but decreased in legacy mosaics. Truffle

biomass averaged 0.5 kg/ha (ranging 0-1.8 kg/ha seasonally)

in untreated timber and legacy stands. Of 28 species found

in timber and legacy stands, 19 were in timber with 7 only

in timber stands. Of the 28 species, 21 were in legacy stands

with 9 only in legacy stands. Rhizopogon was the dominant

genus, with a relative frequency of 40 to 47 percent.

Gautieria and Leucogaster were more frequent in legacy

than in timber stands and Melanogaster and Hysterangium

were more frequent in timber stands. Truffle production

was reduced overall in mosaics (from an overall frequency

of 18 percent in control plots to 13 percent in VDT plots)

in the short term, with heavily thinned patches most reduced

(to 10 percent). Truffle diversity increased to 48 species in

mosaics (vs. the 28 species in controls) and productivity

quickly recovered. Gautieria and Hysterangium decreased

in abundance in mosaics, but Melanogaster increased in

species diversity and biomass. A total of 64 mushroom

species were found before treatment, 37 (19 mycorrhizal)

in legacy stands and 44 (15 mycorrhizal) in timber stands.

Richness of ectomycorrhizal mushrooms was highest in

legacy stands. After VDT, 108 mushroom species were

found in legacy mosaics (vs. 89 species in legacy controls)

and 78 species were found in timber mosaics (vs. 65 in

timber controls). 

Vascular plants—Legacy stands had 27 to 40 species

of understory plants compared to 49 to 87 species in the

timber stands. Of 91 species in timber stands, 51 were not

found in legacy stands and 18 were nonnative species (1

tall shrub, 2 low shrubs, 13 herbs, and 2 grasses). Of 47

species in legacy stands, 4 were not found in timber stands,

including the old-growth associate Pacific yew (Taxus brevifolia Nutt.), and 1 was nonnative. Community structure 

differed with management history, with timber stands

230
dominated by aggressive clonal native shrubs and ferns.

Timber stands had greater cover than legacy stands for total

understory (88 vs. 34 percent), tall shrubs (12 vs. 5 percent),

salal (25 vs. 13 percent), swordfern (16 vs. 3 percent), and

brackenfern (9 vs. 2 percent). Compared to controls, mosaics

initially had reduced understory cover and increased importance of 20 native and 11 exotic species. Two native species

decreased in importance. Three years later, understory

recovered, species richness increased by 150 percent, only

4 exotic species persisted in importance, and 8 natives

increased and 7 natives decreased in importance. Underplanting in mosaics was reestablishing root-rot-resistant

trees in root-rot pockets, increasing the resilience of the

forest, and in other heavily thinned areas, increasing resistance to spread of root rot. After 10 years, some exotic

species persisted at low levels and spatial patterning was

beginning to emerge in the understory. Sparse natural regeneration of shade-tolerant conifers, markedly increased

abundance of understory hardwoods, and good survival of

underplanted trees of high to intermediate shade tolerance

portends a rapid increase in understory diversification. 

Small mammals—Timber stands had 1.5 times the

numbers and 1.7 times the biomass of small mammals in

legacy stands. Keen’s mouse (Peromyscus keeni), a dominant species in natural forests, was rare in both legacy and

timber stands. The creeping vole (Microtus oregoni) was

inordinately abundant in timber stands (3rd ranked) compared to legacy stands (7th ranked) and natural stands. The

montane shrew (Sorex monticolus) was also inordinately

abundant in thinned stands (2nd ranked). Neither management history produced communities typical of natural forests.

After VDT, deer mice (Peromyscus maniculatus), creeping

voles, and vagrant shrews (Sorex vagrans) increased in

abundance in mosaics. No species decreased in abundance.

Northern flying squirrels were twice as abundant in legacy

as in timber stands (1.0/ha vs. 0.5/ha). Townsend’s chipmunks were opposite (0.2/ha vs. 0.8/ha). Douglas’ squirrels

were low in abundance in both timber and legacy stands

(0.1/ha). Flying squirrels decreased in abundance in legacy

mosaics immediately following VDT but recovered within

5 years. Chipmunks increased sharply in legacy mosaics

following VDT and remained high. Douglas’ squirrels did

not respond to VDT in the short term. It remains to be seen

whether flying squirrels and Douglas’ squirrels will increase

over time in mosaics as tree diversity increases and as trees

increase photosynthetic activity and allocate additional

carbon to seeds and ectomycorrhizal associates. California

hazel (Corylus cornuta Marsh var. californica (A. DC.)

Sharp) and bigleaf maple (Acer macrophyllum Pursh) are

present and may begin producing high quality nuts and

seeds for the squirrels in response to the more open canopy

and available light.

Wintering birds—Species richness was higher in timber

(16.2 ± 1.4 species) than in legacy stands (12.2 ± 1.0 species).

Richness remained unchanged in timber mosaics, ranging

from 14 to 22 species 3-5 years after VDT. Richness varied

annually but was consistently higher in legacy mosaics than

in legacy controls in post-VDT years 3 to 5 (annual richness was 12 to 16 species in mosaics vs. 10 to 16 species

in controls). The proportion of stand area used increased in

mosaics for 2 of 8 abundant species (Troglodytes troglodytes

and Melospiza melodia). No species used legacy more than

timber or mosaic stands. Cavity-excavating birds (Picidae)

were present, but low in abundance, in all stands.

Modeling Results

Simply protecting second-growth forest caused the

landscape to go through waves of forest development.

Initially a substantial ecological crunch occurred because

of degraded watersheds and oversimplified stands; a long

time (200 years) was required for these stands to achieve

an old-growth-like condition. Timber management with

minimum constraints produced a landscape inhospitable to

>20 vertebrate species and allowed no recovery of degraded streams; its sustainability was uncertain, but net present

value was maximal. Timber management with riparian

reserves drawn from federal guidelines produced relatively

narrow, well separated strips of late-seral forest in the long

term, unlikely to function fully as late-seral forest because

of their continued adjacency to clearcut and young forests;

clearcutting was intensified in the available uplands due to

removal of streamside and adjacent small patches from forest from management. Biodiversity management, as it was

designed to do, produced significant ecological benefits

(table 1), including supporting a pair of spotted owls and

numbers of deer and elk comparable to the timber management regime. AIM costs were surprisingly low—only a 15-

percent loss in net present value compared to maximizing

net present value of timber extraction. Assuming (as occurred)

increased riparian protection would be mandatory and eliminating costs of improved riparian/mass-wasting management from comparisons, AIM resulted in only a 6-percent

decrease in net present value. Other economic values

increased: decadal revenues increased by 150 percent, forestbased employment quadrupled, and the wood products manufacturing sector diversified and relied more heavily on high

quality wood products and value-added manufacturing

(Lippke et al. 1999). Initially, I included a constraint of 30

percent of the landscape in late-seral forest to support one

pair of spotted owls; the final shifting steady state mosaic

231
maintained >50 percent of the landscape in late seral stages

and <15 percent of the landscape was in clearcuts in any

decade, resulting in a landscape fully permeable to dispersing late-seral species.

DISCUSSION

The similarity between fungal communities in timber

and legacy stands suggests high resiliency in soil food webs

in the face of active management (Carey 2003a, Carey et al.

2002, Schowalter et al. 2003). Timber management, however, reduced fungal dominance and macroscopic fungal mats.

Mechanical disturbance appears to destroy fungal mats and

promote Melanogaster over Hysterangium and Gautieria.

Impacts on truffle production, however, were brief. The

long-term impacts of forest management on truffle production remain unclear, with inconsistent results from across

the region (Carey et al. 2002, Smith et al. 2002). Induced

heterogeneity increased sporocarp diversity to a richness

that rivals that in old growth (Carey et al. 2002). Retaining

unthinned patches in mosaics might help conserve fungal

mats and allow their recolonization as increased photosynthetic activity by trees increases the flow of carbohydrates

to soil food webs and maintains high fungal diversity.

Conventional thinning produced timber stands with rich

understories dominated by clonal natives with numerous

exotics present. Achlorophyllous mycotrophs (parasitic

plants without chlorophyll) were reduced in abundance by

dense understory; retaining unthinned patches in mosaics

would help conserve these species. Understories in the timber stands however, lacked both shade-tolerant trees and

the spatial heterogeneity associated with diverse vertebrate

communities (Carey et al. 1999a). Legacy forests had

depauperate understories and low abundances of small

mammals and wintering birds. Thus, neither historical

management regime had placed stands on a trajectory

toward developing the complexity and diversity of oldgrowth forests. Inducing mosaics increased diversity and

abundance of native species but only slightly increased

exotics. Underplanting is leading to increased spatial heterogeneity. With time, it now appears likely the course of

both timber stands and legacy stands has been altered by

inducing heterogeneity, and that development of biocomplexity, although far from ensured, is more likely than

before treatment. 

Timber and legacy management produced imbalanced

mammal communities, with some species common in natural forests low in abundance. Inducing heterogeneity had

immediate positive effects on forest-floor mammals, but

shade-tolerant midstories and midstory deciduous trees

(e.g., Acer macrophyllum Pursh) will be required to restore

biotic integrity. Chipmunks increased markedly in legacy

mosaics with only brief declines in flying squirrels. Flying

squirrels remained rare (some of the lowest densities ever

recorded in the Pacific Northwest) in the timber stands,

perhaps due to open canopies that impede arboreal travel

and dense understories that promote excessive chipmunk

abundance, make foraging for truffles more difficult, and

increase exposure to predation by large gaps between the

understory and canopy. Heterogeneity had positive effects

on winter birds; cavity-excavating birds, however, remained

low in abundance. Promoting deciduous trees early in stand

development provides both short-lived trees (e.g., Alnus

rubra Bong) for cavity excavation and long-lived trees

(e.g., Acer macrophyllum Pursh and Arbutus menziesii

Pursh) for mammal dens. Legacy retention and decadence

management is essential to maintaining cavity-excavating

birds and forest-floor organic matter. It seems that intentional

232

Table 1—Measures of landscape health in a western Washington landscape in the 

last 100 years of a 300-year simulation under management to maximize net present 

value of timber and active intentional management for multiple values

Timber Biodiversity

Ecological measure management management

Vertebrate diversity (% of maximum possible) 64 100

Forest floor functiona (% of maximum possible) 12 100

Ecological productivityb (% of maximum possible) 19 94

Landscape health (mean of the above 3) 32 98

Source: Adapted from Carey et al. 1999b.

a Composition and structure (relative abundances) of the forest-floor small mammal community measured 

against that in old growth.

b Biomass of northern flying squirrels, Townsend’s chipmunks, and Douglas’ squirrels measured against that 

in old growth.
disturbance can produce spatial complexity at the fine scale

that is important in restoring and maintaining biodiversity

in second-growth temperate, boreal, and tropical forests

(Canham et al. 1990; Carey et al., 1999a, b; Franklin et al.

1997, 2000, 2002; Lindenmayer and Franklin 2002). 

Natural history, comparative, experimental, and modeling studies have demonstrated the value of diverse ecosystem elements from headwater seeps, to fallen trees, to

deciduous components of conifer ecosystems; the importance of spatial heterogeneity in both the vertical and horizontal dimensions and within individual structures; temporal

change (seasonal, interannual, decadal, and submillenial

dynamics) and adaptation to changing environmental conditions; and small, intermediate, and large-scale disturbances

as underpinnings of biodiversity and biocomplexity. Managerially induced homogeneity favors some species over others

resulting in a loss of biotic integrity, benefiting globally

abundant species and exotic species most. No active management after clearcutting also results in loss of biological

diversity and biotic integrity. 

Computer simulations suggest that AIMing for multiple

values can produce wood, water, clean air, recreational

opportunities, revenues to the land manager/owner/trust,

biological diversity, viable populations of species associated

with old forests, and healthy aquatic systems. Simulations

of maximizing wood production and protecting forests without manipulation forecast production of reduced values,

even reduced sustainable revenues, higher risks of loss of

values, new costs, and lack of opportunity for the ecosystems to adapt to change. AIM, however, requires a suite of

techniques, beginning with public involvement in setting

goals and strategies to accomplish goals. Next, geotechnical

analysis of watersheds can be used to identify areas of

unstable slopes and potentially erodable colluvium that,

along with headwater seeps and streams, and larger, fish

bearing streams, can be buffered appropriately and provide

a template for legacy retention. Watershed analysis is followed by design, construction, rehabilitation, and maintenance of efficient and low-impact transportation systems.

Intentional ecosystem management then incorporates modern silvicultural methods arrayed into management pathways

that provide for directional development of ecosystems in

shifting steady-state mosaic landscapes. These methods

might include variable-retention harvests systems that emphasize legacy retention as much as wood removal, multispecies planting, precommercial thinning to promote growth

and biodiversity, multiple variable-density commercial

thinnings to harvest wood while protecting legacies and

inducing spatial heterogeneity to stimulate development 

of biocomplexity, multispecies management that includes

deciduous trees and shrubs in conifers forests, and long or

alternating long and short rotations. AIM has potential to

contribute to economic, social, and environmental sustainability.

ACKNOWLEDGMENTS

I thank the numerous people that participated in the

study and the U.S. Army, Fort Lewis, the Pacific Northwest

Research Station, and the USDA National Research

Initiative for funding. 

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Spies, T.A.; White, P.S. 1990. Light regimes beneath

closed canopies and tree-fall gaps in temperate and

tropical forests. Canadian Journal of Forest Research.

20: 620-631.

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76(2): 131-140.

Carey, A.B. 2003b. Restoration of landscape function: 

Reserves or active management? Forestry. 

76(2): 225-234.

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Carey, A.B.; Harrington, C.A. 2001. Small mammals in 

young forests: implications for sustainability. Forest

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Carey, A.B.; Horton, S.P.; Biswell, B.L. 1992. Northern 

spotted owls: influence of prey base and landscape

character. Ecological Monographs. 62: 223-250.

Carey, A.B.; Kershner, J.; Biswell, B.; de Toledo, L.D. 

1999a. Ecological scale and forest development: squirrels, dietary fungi, and vascular plants in managed and

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Carey, A.B.; Lippke, B.R.; Sessions, J. 1999b. Intentional 

systems management: managing forests for biodiversity.

Journal of Sustainable Forestry. 9: 83-125.

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Carey, A.B.; Thysell, D.R.; Brodie, A.W. 1999c. The Forest 

Ecosystem Study: background, rationale, implementation, baseline conditions, and silvicultural assessment.

Gen. Tech. Rep. PNW-GTR-457. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 129 p.

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R.J., eds. 1993. Demography of the northern spotted

owl. Studies in Avian Biology. 17: 1-122.

Franklin, J.F.; Berg, D.R.; Thonburgh, D.A.; Tappeiner 

J.C., II. 1997. Alternative silvicultural approaches to

timber harvest: variable retention harvest system. In:

Kohm, K.A.; Franklin, J.F., eds. Creating a forestry for

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Washington, DC: Island Press: 111-139. 

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A.; Magnuson, J.; Perry, D.A.; Waide, R.; Foster, D.

2000. Threads of continuity. Conservation Biology in

Practice. 1: 9-16.

Franklin, J.F.; Spies, T.A.; Van Pelt, R.; Carey, A.B.; 

Thornburgh, D.A.; Berg, D.R.; Lindenmayer, D.B.;

Harmon, M.E.; Keeton, W.S.; Shaw, D.C.; Bible, K.;

Chen, J. 2002. Disturbances and structural development

of natural forest ecosystems with silvicultural implications, using Douglas-fir as an example. Forest Ecology

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Li, C.Y.; Maser, C.; Maser, Z.; Caldwell, B. 1986. Role 

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46: 411-414.

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biodiversity: a comprehensive multiscaled approach.

Washington, DC: Island Press. 351 p.

Lippke, B.R.; Sessions, J.; Carey, A.B. 1999. Economic 

analysis of forest landscape management alternatives.

CINTRAFOR special paper 21. Seattle, WA: University

of Washington, College of Forest Resources. 157 p. 

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emergence of transformational values in America.

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western Washington forests. Ecological Applications.

13(5): 1204-1211.

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richness, abundance, and composition of hypogeous and

epigeous ectomycorrhizal fungal sporocarps in young,

rotation-age, and old-growth stands of Douglas-fir

(Pseudotsuga menziesii) in the Cascade Range of

Oregon, U.S.A. Canadian Journal of Botany. 

80: 186-204.

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234
1 Wildlife Biologist, MeadWestvaco, P.O. Box 1950, Summerville, SC 29484, USA. Email for corresponding author: wmb3@meadwestvaco.com

2 Professor, Department of Forest Resources, Clemson University, Clemson, SC 29634, USA

Balancing Ecosystem Values Proceedings, Biodiversity

The Effect of Forested Corridors Within Harvested 

Pine Plantations on Herpetofauna Assemblages

William M. Baughman1 and David C. Guynn, Jr.2

INTRODUCTION

Interest in using amphibians and reptiles as indicators 

of forested ecosystem health has increased in the last two

decades (Bury and Corn 1988). Amphibians and reptiles are

good bioindicators of environmental health because they are

exposed to both aquatic and terrestrial environments, have

small home ranges, and relatively limited dispersal (Blaustein

et al. 1994, Blaustein and Wake 1990, Dunson et al. 1992).

Amphibians are integral components of most ecosystems,

often constituting the highest fraction of vertebrate biomass

(Burton and Likens 1975, Kiester 1971). Amphibians play

key roles in forest ecosystems, especially in forest detritus

food webs, where they convert small invertebrate biomass

into larger sized prey for other vertebrates (Pough 1983).

Therefore, declines in amphibian and reptile populations

could significantly affect other organisms.

Human activities affect many populations of amphibians,

reptiles, and other animals. Forest management is one

activity that has drawn particular attention. Although certain

ABSTRACT

We determined the effect of forested corridors within clearcuts on herpetofauna in the Coastal Plain of South Carolina.

We studied four identically managed 20-ha plantations of loblolly pine (Pinus taeda L.). Three randomly chosen sites

retained a 100-m unharvested forested corridor within a clearcut treatment, and the other site was an unharvested control.

All sites were monitored from January 1997 through December 1999 (16 months preharvest and 20 months post-harvest)

using two standard drift fence arrays. Forty-two species were captured totaling 2,681 animals, with a recapture rate of 8 

percent. The number of anurans and salamanders captured in harvested areas did not differ significantly from the unharvested

control. No significant difference was detected pre- and post-treatment evenness, Pielou’s J, within treatment and control.

Anuran abundance decreased, while Pielou’s J increased significantly with increases in the density of post-treatment coarse

woody debris. Despite intensive forest management, these sites continued to support diverse and herpetofaunal assemblages.

KEYWORDS: Harvesting, pine plantation, corridors, forest management, herpetofauna, clearcuts.

235

forest management practices benefit many wildlife species

(Harlow and Van Lear 1981, Harlow and Van Lear 1987,

Sweeney et al. 1993, Sweeney and Wigley 1999), their

effects on amphibians and reptiles must be better understood before forests can be managed to benefit all wildlife

(Raymond and Hardy 1991).

Most research on the effects of forest management on

herpetofaunal assemblages was conducted in hilly or rocky

terrain. Clearcutting in the Pacific Northwestern United

States decreased the number of terrestrial amphibians by

reducing the availability of moist microhabitats and by limiting foraging and reproductive opportunities (Dupuis et al.

1995). In North Carolina, clearcuts averaged about 60 percent fewer marked animals than forested controls the first

year after harvest, and salamanders were completely absent

2 years post-harvest (Ash 1988). Logging in the southern

Appalachians resulted in a decrease in salamander populations of 70 to 80 percent, and clearcutting on USDA Forest

Service land in western North Carolina was estimated to

eliminate 13.7 million salamanders annually (Petranka et
al. 1993, Petranka 1994). Several other studies have also

reported negative changes in amphibian assemblages following timber harvest (Blaustein and Wake 1990, Bury 1983,

Corn and Bury 1989, Harpole and Haas 1999, Pough et al.

1987, Raymond and Hardy 1991).

Although amphibians may be negatively affected by

timber management practices, effects may be temporary, as

some herpetofaunal populations recover over time (Dodd

1991, Enge and Marion 1986, Pough et al. 1987). In South

Carolina, managed pine plantations harbored more amphibian species and individuals than expected (Bennett et al.

1980). Long-term studies found more Plethodon elongatus

in young stands than older stands, but these sites required

increased sampling effort because of understory vegetation

(Diller and Wallace 1994). However, interpreting results

from most forest management studies is complicated by

small sample sizes and lack of pre- and post-treatment data.

Here, we report results from the first 3 years of a replicated

20-year experiment designed to examine the effect of

Westvaco’s Ecosystem-Based Multiple Use Forest Management System (Muckenfuss 1994), which uses maintained

forested corridors within clearcuts, on herpetofauna assemblages.

STUDY AREA

We conducted the study in South Carolina on MeadWestvaco’s Jericho and O'Bryan Units located near the

towns of Ravenel (Charleston County) and Cottageville

(Colleton County), respectively. The study areas had slopes

generally <2 percent and elevations of 20 to 30 m above

mean sea level. The soil was somewhat poorly drained with

a sandy loam or loam surface layer overlaying a heavy clay

subsoil, a near-neutral pH and high levels of phosphorus.

Sites were very productive for loblolly pine (Pinus taeda L.).

Study sites were located in intensively managed, 19-

year-old loblolly pine plantations that had been sheared,

root raked, and bedded when established. All sites were

located within 16.09 km of each other. Mean diameter at

breast height and tree density among all sites was 27.9 cm

and 672.5 trees/ha, respectively. Vegetation consisted of a

canopy of loblolly pine with a midstory of wax myrtle

(Myrica cerifera), sweetgum (Liquidambar styraciflua), red

maple (Acer rubrum), supplejack (Berchemia scandens),

and grape (Vitis rotundifolia). The understory was composed

of grape, poison ivy (Toxicodendron radicans), red buckeye (Aesculus pavia), heart-leaf (Hexastylis arifolia), Easter

lily (Zephyranthes atamasco), false nettle (Boehmeria

cylindrical), and Virginia creeper (Parthenocissus 

quinquefolia).

METHODS

To assess responses of herpetofaunal assemblages to

timber harvesting with maintained corridors, we chose four

identically managed 20-ha sites. Three were assigned at

random to retain a 100-m wide unharvested forested corridor running the length of the site within a clearcut (Jericho

A, O’Bryan B and C), and the remaining site was assigned

as an unharvested control (O’Bryan). 

To assess herpetofaunal responses, two standard drift

fence arrays (Bury and Corn 1988) were located in the harvested portions (>25 m from the edge) of each treatment

site (fig. 1), and within the unharvested control. Arrays

were made from 15-m sections of 60-cm high aluminum

flashing, placed in the ground 20 cm deep (Corn 1994) and

stabilized with stakes anchored to the fence by cable ties

(Gibbons and Semlitsch 1981). Pitfall traps were 7.5 L

plastic buckets located at the array ends and in the center.

We paired two double-ended funnel traps on opposite sides

of each leg of the array, 7.5 m from the ends. Funnel traps

were constructed of aluminum window screening and were

45.7 cm high x 45.7 cm wide x 76.2 cm long with an interior funnel opening 15.2 cm diameter. We removed all 

vegetation 30 to 40 cm from the base of the fence and any

vegetation within 6 m of the ground that overhung the fence

(Dodd and Scott 1994). All drift fence arrays were monitored from January 1997 through December 1999 (16 month

preharvest and 20 month post-harvest) with traps opened

for the same 8 days in two blocks of four consecutive days

each month. When traps were open, they were checked

daily for a total of 288 nights. 

We recorded the species, sex, life stage, snout-vent

length and total length (to the nearest mm), mass (to the

nearest 0.01 g using an electronic balance), date and location of all animals captured. Salamanders, anurans, and

lizards were cohort-marked by toe-clipping. Snakes and

turtles were individually marked with 14 mm PIT tags and

shell notching, respectively. After processing, we immediately released all animals on the opposite side of the fence. 

We sampled first season (pretreatment) and third season

(second year post-treatment) habitat variables to determine

their relationship to herpetofaunal responses. We sampled

understory vegetation and litter depth on the entire site,

using a 60.35 x 60.35 m grid and >50 points/site. Understory

vegetation was considered to be within 1.37 m of the ground.

Down woody debris and bare soil greater than 5.08 cm in

diameter was tallied. Ocular estimates of percentage of

understory vegetation, woody debris, and bare soil were

made for each point using the Geographic Resource

236
237

Solutions densitometer. We measured leaf litter depth at

each point using a ruler.

We used repeated measures of analysis of variance and

Type III sums of squares to test the null hypothesis that

monthly capture differences preharvest and post-harvest for

groups (anurans, salamanders, lizards, snakes, and turtles)

were equal between clearcut/corridor and control. Monthly

captures per site were totaled by group to form the sample

units. 

We examined traits including snout-vent length, total

length, and mass for adults of commonly occurring species

to determine effects of site and treatment. We used analysis

of variance to test for differences in mean values (snoutvent, total length, and mass) by species, pre- and post-harvest. We then used Duncan’s Multiple Range test to group

means.

We calculated Margalef’s species richness and Pielou’s

evenness index (J) for amphibian and reptile assemblages

at each site and used a Students t-test to examine differences

among sites and treatments. We used Pearson correlation

analysis to examine patterns of herpetofaunal abundance,

richness, and evenness in relation to differences in habitat

attributes among sites. Significance level was set at α=0.05

for all test. All analysis were conducted using the GLM

and CORR procedures in SAS (SAS Institute, Inc. 1987).

RESULTS

Forty-two species were captured totaling 2,681 animals

with a recapture rate of 8 percent (204). Anurans constituted

84 percent of all animals captured, followed by salamanders

(10 percent), lizards (3 percent), snakes (2 percent), and

turtles (1 percent) (table 1). 

No difference was detected in the number of anurans,

salamanders, lizards, snakes, or turtles captured in the harvested areas compared to the unharvested control. Statistical

power was ≥46 percent.

We calculated scores for richness and evenness (J)

(table 2) and were unable to detect a significant difference

among site and between pre- and post-treatment. 

Mean snout-vent lengths of marbled salamanders

(Ambystoma opacum) did not differ significantly by site

pretreatment or post-treatment, but total length differed significant by site pretreatment, with site A different from the

other sites. However, no significant difference was detected

post-treatment. No significant difference was observed pretreatment or post-treatment for mass. Snout-vent length for

eastern narrow-mouthed toad (Gastrophryne carolinensis)

was not significantly different by sites pretreatment or posttreatment. A significant difference was observed by site

pretreatment for mass with site A having heavier animals.

However, no difference was detected post-treatment.

Southern toad (Bufo terrestris) did not differ across sites in

snout-vent length or mass pretreatment and did not differ

post-treatment for snout-vent length. Because of insufficient

sample size for southern leopard frogs (Rana utricularia)

pretreatment, no test of significance was conducted. However, there were no post-treatment differences for snoutvent length or weight for southern leopard frogs. Statistical

power for all tests was ≥85 percent.

Anuran abundance was negatively correlated with

coarse woody debris (r = -0.99, p = 0.008) post-treatment.

Pielou’s J indicia was found to be significantly associated

with post-treatment coarse woody debris (r = 0.98, p = 0.01).

DISCUSSION

Numerous comparative studies have reported declines

in herpetofauna population size and species richness within

Figure 1—Trapping array for sampling a 20-ha loblolly pine stand for

impacts of clearcutting with maintained forested corridors on herpetofauna

in the Coastal Plain of South Carolina.
Table 1—Number of individuals captured in clearcuts by site in intensively managed pine plantations in South Carolina, 1997-1999

Harvest site A Harvest site B Harvest site C Unharvested control

Year

Species 1997 1998 1999 1997 1998 1999 1997 1998 1999 1997 1998 1999Acris gryllus (southern cricket frog) 1 -- -- -- -- -- 1 -- 1 -- -- --Bufo terrestris (southern toad) 49 36 22 37 31 51 42 23 70 51 11 64Gastrophryne carolinensis (eastern 

narrowmouth toad) 27 20 11 76 155 74 267 94 88 66 36 51

Hyla squirella (squirrel treefrog) 2 3 -- 2 29 8 8 20 12 2 2 --Hyla sp. (all other species) 7 4 1 -- 10 1 2 9 -- 2 -- 1Pseudacris sp. (all species) 1 7 8 -- -- -- 3 -- -- 1 1 --Rana clamitans (green frog) 13 -- 1 16 -- 2 19 -- -- -- -- --R. utricularia (southern leopard frog) 18 63 23 -- 87 46 3 168 163 1 11 19Scaphiopus holbrookii (eastern 

spadefoot toad) -- -- -- 1 -- -- -- 1 -- -- -- --

All anurans 118 133 66 132 312 182 345 315 334 123 64 135

Clemmys guttata (spotted turtle) -- -- -- -- -- -- -- 2 2 -- 1 --Kinosternon subrubrum (eastern mud turtle) 2 1 -- 2 6 1 5 5 5 3 2 1All turtles 2 1 -- 3 7 1 5 7 7 3 4 2Anolis carolinensis (green anole) 8 1 3 5 3 -- -- 1 -- -- 5 2Cnemidophorus sexlineatus (sixlined racerunner) -- 1 -- -- -- -- -- -- -- -- -- --

Eumeces sp. (all species) 3 -- 2 -- -- -- 1 -- -- 3 1 2Scincella lateralis (ground skink) 1 1 4 1 1 -- 2 -- 3 3 1 8

All lizards 12 3 9 6 4 -- 3 1 3 6 7 12

Coluber constrictor (northern black racer) 2 -- 4 -- 1 -- 3 1 1 -- -- --Diadophis punctatus (southern ringneck snake) -- -- -- -- -- -- 1 1 1 -- -- 1Lampropeltis getula (eastern king snake -- -- -- -- -- 1 -- 2 1 -- -- --Nerodia sp. (all species) -- -- -- 1 1 -- -- 1 2 -- -- --Thamnophis sirtalis (eastern garter snake) -- -- 2 -- -- -- -- 2 1 -- -- --All snakes 21 91 2 1 7 76 13 1Ambystoma mabeei (Mabee’s salamander) -- -- -- 2 1 -- -- -- -- 1 -- --A. maculatum (spotted salamander) -- -- -- 1 1 -- 16 3 9 -- 1 3A. opacum (marbled salamander 23 9 4 7 7 5 10 16 26 22 11 38A. talpoideum (mole salamander) 1 -- -- 2 2 2 2 4 13 4 2 3Eurycea quadridigitata (dwarf salamander) -- -- -- -- -- -- -- -- -- -- 1 --Plethodon variolatus (SC slimy salamander) 4 1 1 -- -- -- 7 1 -- -- -- 1All salamanders 28 10 5 12 11 7 33 24 48 27 25 45

238
recently clearcut habitats. However, we found no significant differences in the number of amphibian captures among

control and treatment sites. This is in contrast with other

studies that have documented significantly lower abundance of amphibians in clearcut stands as compared to

forested controls (Ash 1988, deMaynadier 1996, Petranka

et al. 1993, Sattler and Reichenback 1998). The results of

our study, however, are similar to those of Corn and Bury

(1991) who documented no significant differences in total

abundance of salamanders between clearcuts and forested

areas in the Pacific Northwest, but noted that some species

appeared to be more sensitive to canopy removal than others.

In Kentucky, Adams et al. (1996) reported no observed

difference in numerical abundance or species richness

among silvicultural prescriptions. In the southern Cascade

Range in Washington, all species captured in unmanaged

forests also occurred in intensively managed stands (Aubry

2000).

We detected a decline in lizards from the harvested areas

which was due to two species, green anole (Anolis carolinensis) and ground skink (Scincella lateralis). The pooled

reptile data showed no declines in abundance, however,

which is similar to the findings of Adams et al. (1996), who

indicated enhanced species richness and abundance of reptiles following timber harvesting. The presence of slash in

clearcuts has been hypothesized to enhance cover for reptiles and their prey in South Carolina (Phelps and Lancia

1995).

We detected a slight decline in the number of amphibians in the second year of the study for the control. The

second year of the study partially overlapped with the first

year of harvest on the treatment sites. During the second

year, there was a moderate drought during the spring and

summer months (National Oceanic and Atmospheric Administration 1998). However, there were two 5-cm rains that

generated several stagnant pools on the harvested sites,

which produced large numbers of anurans. No pools were

observed on the control sites. It is hypothesized that the

difference in breeding sites was related to a decrease in

evapotranspiration in the harvested sites. This hypothesis is

also supported by well-water data from the same soil type,

which documented an increased water table level following

clearcutting (Xu et al. 1999).

We found no significant change in evenness among 

pre-and post-treatment, while H was significantly different.

In Texas, H and J indices were significantly greater in

clearcuts than control treatments (Foley 1994). Our work is

supported by work in Kentucky that reported no difference

among silvicultural prescriptions in abundance or species

richness of amphibians, but diversity varied among prescriptions (Adams et al. 1996). Life history traits of various

taxa may contribute to discrepancies among studies; therefore, caution should be used when using diversity or evenness indices for comparison between habitats or studies.

We thought that increased exposure of the forest floor

to sun and wind would desiccate harvested habitats, thus

reducing its quality for amphibians, which would result in

decreased growth or health. However, we found no such

change in growth or health of commonly occurring species.

In another study that examined the effects of a clearcut on

individual traits, no significant effects of clearcut were

detected on body size or whole body and egg nonpolar lipid

percentages for mole salamanders (Ambystoma talpoideum)

(Chazal and Niewiarowski 1998), although mole salamanders in Chazal and Niewiarowski’s study were not exposed

to the mechanical disturbance of clearcutting. In our study,

we documented no direct effects of timber harvest on individual traits.

We found that the percentage of woody debris was

either insignificant or had a negative relationship with

abundance. Exposed mineral soil showed no significant

relationships. DeMaynadier (1996) also reported similar

findings for downed woody debris. DeGraaf and Rudis

(1990) found that litter depth was the only variable that

was related to herpetofaunal community measures. 

239

Table 2—Species richness and evenness indices pre- and post-harvest for herpetofauna 

captured in pine plantations in South Carolina, 1997-1999

Margalef Pielou J

Site Pretreatment Post-treatment Pretreatment Post-treatment

Harvest site A 2.99 4.51 0.73 0.65

Harvest site B 2.63 3.01 0.52 0.56

Harvest site C 3.03 3.60 0.41 0.56

Unharvested control 3.14 3.35 0.57 0.64
240

Overall, clearcutting had very little effect on the herpetofaunal assemblages in the intensively managed pine

plantations we studied. Soil and litter depth may have contributed to the maintenance of herpetofauna populations

during and following harvesting activities on these fertile

Coastal Plain soils. In addition, the family Ambystomatidae,

which comprised a majority of the salamanders in our study,

may be more resistant to habitat changes than other genera

previously studied. Despite intensive forest management,

these sites continue to support diverse and abundant herpetofauna communities.

ACKNOWLEDGMENTS

We thank Elizabeth T. Bourgeois, Dr. Hugh G. Hanlin,

Dr. J. Drew Lanham, Dr. David H. Van Lear, and Dr. T.

Bently Wigley for comments and reviews of this manuscript. We also thank all the employees of MeadWestvaco’s

Southern Forest who helped with logistics. Thanks also go

to Dr. William C. Bridges for his assistance with statistical

analysis. Special thanks go to Chris Muckenfuss and Jason

Slater who assisted with data collection under extreme field

conditions. Monetary support for this project was provided

by MeadWestvaco. All animals were handled in accordance

with Clemson University Animal Research Committee

Protocol #97-052.

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1 Research Assistant, Department of Forest Science, 2 Associate Professor, Oregon State University, Corvallis, OR 97331, USA. 

Email for corresponding author: Liane.Beggs@oregonstate.edu

3 Castor International, 1604 8th Avenue S.W., Olympia, WA 98502, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Vegetation Response to Alternative Thinning 

Treatments in Young Douglas-fir Stands

Liane R. Beggs,1 Klaus J. Puettmann,2 and Gabriel F. Tucker3

INTRODUCTION

Young, managed Douglas-fir (Pseudotsuga menziesii

(Mirb.) Franco) forests are prevalent in the forests of western Oregon, Washington, and British Columbia, often replacing what was once “old-growth” forest (Hunter 2001).

Structural features associated with old-growth forests such

as large diameter trees and snags, multi-layered canopies,

and well-developed understories are often absent from these

young stands (Franklin and Spies 1991, Franklin et al. 2002,

Halpern and Spies 1995). Such attributes have been identified as key ecosystem components important for late successional wildlife habitat, epiphyte substrate, understory

vegetation heterogeneity, and nutrient cycling (Bailey et 

al. 1998, Forsman et al. 1984, Rambo and Muir 1998,

ABSTRACT

The Young Stand Thinning and Diversity Study was designed to test whether management of young stands, specifically

alternative thinning regimes, can accelerate development of late-successional habitat and, therefore, enhance biodiversity

while maintaining wood production goals. The study is located in the lower Cascade Range of central Oregon and consists

of four replications of four thinning treatments (treatment areas average 30 ha each) in 30- to 50-year-old second-growth

Douglas-fir stands (Pseudotsuga menziesii (Mirb.) Franco). Treatments include an uncut control, a heavy thin, a light thin,

and a light thin with gaps. Unlike traditional thinning, this study sought to maintain overstory diversity by specifically

retaining hardwoods and conifer species other than Douglas-fir. A complex set of responses (e.g., vegetation, bird and small

mammal populations, mushroom productivity) were measured repeatedly after treatment implementation. Results of vegetation data indicate that only the heavy thinning maintained open canopies for multiple years and accelerated development of

large trees, one important component of late-successional habitat. In addition, thinning did not result in higher mortality

rates, but decreased density related mortality of Douglas-fir. Also, mortality was low for nondominant overstory species that

were intentionally retained during thinning. Finally, vertical canopy structure showed no immediate differentiation among

treatments. Tree crowns likely did not have sufficient time to respond, and evidence suggests that retention of nondominant

tree species may have prevented simplification of crown structure in low thinnings. 

KEYWORDS: Silviculture, Douglas-fir, overstory response, vertical structure, tree growth.

243

Trofymow et al. 1991). Consequently, young managed

forests may not be capable of supporting diverse species

assemblages, specifically those dependent on late-successional habitat (Halpern and Spies 1995).

Concern over how to best manage young stands in order

to promote late-successional habitat gave rise to the Young

Stand Thinning and Diversity Study (YSTDS). This study

was designed to test whether management of young stands,

specifically alternative thinning regimes, can accelerate

development of late-successional habitat and, therefore,

enhance biodiversity while maintaining wood production

goals. Research questions addressed by this study include

effects of thinning on vegetation (Beggs et al., n.d.; Beggs,

n.d.; Bohac et al. 1997), small mammals (Garman 2001),
244

birds (Hagar et al.1996, Hagar et al. 2004), and soil (Allen

1997). Though the study covers a broad realm of scientific

inquiry, this paper focuses on early (5 to 7 years post-treatment) overstory vegetation response to the thinning treatments. 

Thinning has traditionally been applied to enhance 

timber production, not for structural enhancement (Thysell

and Carey 2001). Therefore, it remains uncertain if thinning can accelerate development of large trees, a layered

canopy, and a well-developed understory. Although tree

growth has been shown to increase following thinning

(Marshall and Curtis 2002, Staebler 1956), traditional thinning may not sufficiently reduce competition among the

largest, most dominant trees to increase their growth and

accelerate development of large trees like those important

for late-successional habitat. In addition, formation of

multi-layered canopies and understory layers may take several years to develop. Tracking the changes in vegetation

response over a long period of time is an important feature

of the YSTDS. The present study will provide reference

information regarding initial vegetation response that will

facilitate future interpretation of successional patterns and

development.

Vegetation response investigated by this study includes

treatment comparisons of (1) changes in overstory canopy

cover, (2) growth of the largest 10 to 30 Douglas-fir per

hectare, (3) growth of all Douglas-fir ≥ 8 cm in diameter

1.37 m above ground (d.b.h.) (4) vertical crown structure,

and (5) mortality of individual tree species. 

METHODS

Study Design

The study is located in the lower Cascade Range of central Oregon in 30- to 50-year-old second-growth Douglasfir stands. It consists of four blocks, with each block

containing four treatments (providing a total of 16 treatment units). Blocks are designated as Cougar Reservoir

(CR), Mill Creek (MC), Christy Flats (CF), and Sidewalk

Creek (SC). Treatment units range in size from 15 to 53

hectares (ha), with a mean of 30 ha. Pretreatment stand exam

data indicates that basal area (BA) within blocks was similar among treatment units (Beggs et al., n.d.); therefore,

starting conditions were assumed to be similar. 

Treatments include an uncut control, a heavy thin, a

light thin, and a light thin with gaps (hereafter abbreviated

as LtGaps). Treatments were applied between 1995 and

1997. Unlike traditional thinning, these treatments sought

to maintain overstory diversity by specifically retaining

hardwoods and conifer species other than Douglas-fir. The

control maintained stand densities of approximately 650

trees per hectare (t/ha). The light thin reduced stand densities

to 250-300 t/ha and was representative of a typical commercial thin. In an attempt to mimic densities believed to be

more similar to initial old-growth stand densities (Tappeiner

et al. 1997), the heavy thin reduced stand densities to 125

t/ha. Finally, the LtGaps treatment was intended to mimic

small-scale disturbance. Therefore, the entire stand was

thinned to 250-300 t/ha with 0.2 ha gap cuts spaced evenly

throughout the stand (1 gap per 2 ha). This produced the

following three subtreatments within the LtGaps treatment:

(1) gap: the 0.2 ha gap, excluding the outermost 7.5 m ring;

(2) edge: the circular area surrounding the gap cut, extending 7.5 m into the gap and 28.1 m out from the gap/forest

interface; and (3) the stand matrix: the remaining portion 

of the thinned stand (see Sampling and figure 1 for clarification on subtreatment definitions).

Sampling

Vegetation sampling occurred in the summer of 1995,

1996, or 1997, depending on the time of harvest completion. This data will be referred to as “first-year vegetation

sampling,” inferring it is data describing the earliest postharvest response. Resampling was completed during the

summer of 1999 and again in 2001. These data depict vegetation response 3 to 5 years and 5 to 7 years post-harvest,

respectively. Most information presented in this paper will

focus on results obtained from the first-year data and 2001

data.

Tree sampling was conducted using 0.1-ha circular 

permanent plots. For the control, heavy, and light thin treatment units, plots were randomly located along systematically

placed transects. Sampling covered approximately 7.5 percent of the area in these treatment units. For the LtGaps

treatment units, there was interest in capturing variation

occurring among the gap, edge, and matrix. Therefore, in

these treatment units, plots were placed in each of 10 gaps,

10 edges, and 10 stand matrix sites that had been randomly

selected (30 total plots per treatment unit). Location of subtreatment plots was determined by the radius of the sampling plot (17.8 m; fig. 1). Therefore, gap plots sampled

only the gap interior. Edge plots sampled the outermost

ring of the gap, the gap/forest interface, and a section of

forest extending from the gap into the thinned forest. Stand

matrix plots sampled the remainder of the thinned stand

that was beyond that which was included in the edge sampling (fig. 1).
In each plot, overstory percent cover was measured centrally and at four cardinal directions. The d.b.h. for all trees

≥ 5cm was also measured in each plot. A random subsample of trees in each plot was measured once for height and

crown base height in 1999. 

Data Analysis

Canopy cover, absolute growth of the largest 10 to 30

Douglas-fir, relative growth of all Douglas-fir ≥ 8 cm d.b.h.,

vertical crown structure differentiation, and mortality of

individual tree species were compared among treatments.

For canopy cover, multiple measurements within plots

were averaged to provide plot means. For control, light

thin, and heavy thin treatment units, these plot totals were

then averaged to provide mean treatment unit values. For

the LtGaps treatment units, subtreatments (gap, edge, and

matrix) were sampled equally but did not comprise equal

proportions of the total treatment unit. To adjust for this

and permit comparison with other treatments, weighted

averaging was used. Subtreatment means were calculated

by averaging plot means within each subtreatment, weighting these averages by the areal proportion of a subtreatment

in the total treatment unit, and then averaging these numbers

to provide treatment unit means. 

Annual growth of each Douglas-fir tree in a treatment

unit was calculated by subtracting the first-year d.b.h. from

the 2001 d.b.h. and dividing by the number of years between

measurements. For all trees ≥ 8 cm d.b.h., relative growth

(absolute growth divided by first-year d.b.h.) was used in

order to account for differences in average stand d.b.h.

among treatments (by removing small trees, thinning inherently increased average stand d.b.h. in thinned treatments

relative to controls). To assess growth of the largest 10, 20,

and 30 t/ha, the largest 1, 2, and 3 trees from each 0.1 ha

plot, respectively, were selected. For these trees, absolute

growth was calculated because average d.b.h. of large trees

did not differ among treatments. Treatment unit means were

calculated by averaging growth of all trees in each treatment unit. 

Vertical crown structure was quantified using the Foliage

Height Diversity (FHD) index (MacArthur and MacArthur

1961). The FHD is comprised of two components: richness

and evenness, making it nearly identical to the ShannonWeiner diversity index (Margalef 1958). Richness, for this

study, was defined as the number of 5-m layers containing

canopy vegetation whereas evenness was the relative abundance of vegetation within each layer. Mortality for each

species (for list of all species examined, see Beggs et al.,

n.d.) was calculated as the percentage of all trees (by species)

present during first-year vegetation sampling that had died

by 2001. 

Treatment comparisons were performed by using a randomized complete block model. All multiple comparison

tests employed the Tukey-Kramer adjustment with the significance level set at α = 0.05 (Ramsey and Schafer 2002).

For more complete details on statistical methods and analysis, refer to Beggs et al. (n.d.).

RESULTS AND DISCUSSION

Overstory Cover

The overstory canopy was successfully opened by thinning. Less overstory cover was found in all thinned treatments relative to the control 1 year after thinning (fig. 2).

In addition, the heavy thin had less overstory cover than

the light thin. By 2001, the heavy thin and LtGaps thin still

had less canopy cover than the control, but cover in light

thin was no longer significantly different from the control

(fig. 2), i.e., a heavy thinning and a light thinning combined with gap formation produced a canopy that remained

fairly open for several years. Following a more conventional light thin, however, the open canopy closed relatively

quickly. This difference is important because successful

establishment of an understory layer is often dependent

upon extended periods of canopy openness (Alaback and

Herman 1988, Bailey et al. 1998, Klinka et al. 1996). Though

some small changes may occur during brief phases of open

conditions and persist for extended periods of time (Alaback

and Herman 1988, Bailey et al. 1998, Thomas et al. 1999),

245

Figure 1—Schematic of sampling plot layout for the treatment light thin

with gaps. 
the rapid closure of the canopy after light thinning may

inhibit establishment of a prominent understory layer.

Growth

Growing conditions for the residual trees were most

improved following heavy thinning. This is apparent by

higher relative diameter growth of all Douglas-fir ≥ 8 cm

d.b.h. in the heavy thin than in the control. Also, the LtGaps

thin had slightly higher relative growth than the control,

likely due to increased resources along gap/edge interface.

The light thin did not result in higher diameter growth 

relative to the control and actually had significantly lower

growth than the heavy thin. Heavier thinning also provided

favorable growing conditions for the dominant stand components. Only the heavy thin produced higher absolute

growth among trees relative to the control for the dominant

overstory trees (fig. 3). These results suggest that traditional thinning densities are not low enough to accelerate the

development of large trees, an important component of late

successional habitat. Apparently the largest trees are already

in a dominant position so that the removal of less dominant

trees by low thinning has little impact on their growth. This

suggests that long-term improvement of growing conditions

for the largest trees is only likely to occur by repeated thinning to densities much lower than those of a traditional low

thin.

Vertical Structure

Thinning did not result in immediate differentiation of

crown layers among treatments. By 2 to 4 years after harvest completion, no difference was found among treatments

in the FHD index. When the FHD index was broken into

richness and evenness, neither component differed among

treatments. Lack of distinction among treatments indicates

that crown extension and epicormic branching (Franklin et

al. 2002) has not yet begun in these stands. Given the relatively short time of post-treatment response examined,

these results are not surprising. However, these results also

show that canopy structure was not simplified during the

thinning, even though a low thinning was prescribed.

Preservation of nondominant overstory species may have

permitted retention of lower layers of canopy vegetation,

thereby maintaining original partitioning of vegetation in

the canopy. 

Mortality

High mortality following thinning was not evident for

Douglas-fir or other nondominant species. Douglas-fir and

all combined hardwoods had significantly higher mortality

in the control than in all thinned treatments. Golden chinquapin (Chrysolepis chrysophylla (Dougl. ex Hook.)) was

the only other species to have a difference in mortality

among treatments, with higher mortality in the control than

in the heavy thin or the LtGaps thin (mortality in the light

thin did not differ from that of the control). These findings

suggest retention of non-Douglas-fir species during thinning will not be counteracted by subsequent high post-thinning mortality of these species. Instead, thinning decreased

density related mortality in the short term. In addition, the

lower mortality of Douglas-fir in the heavy thin relative to

the control suggests that a high intensity of thinning, like

that applied in this study, did not result in high stand instability or mortality.

246

Figure 2—Overstory cover for each treatment unit. CR = Cougar

Reservoir, MC = Mill Creek, CF = Christy Flats, SC = Sidewalk Creek

Year 1 = 1995, 1996, and 1997 sampling.

Figure 3—Growth of largest Douglas-fir (20 trees per hectare). CR =

Cougar Reservoir, MC = Mill Creek, CF = Christy Flats, SC = Sidewalk

Creek.
CONCLUSION

In summary, thinning dense stands altered overstory

conditions in the short term. However, overstory response

was affected by the intensity of thinning. Thinning to densities similar to those found in the light treatment of this

study produces only temporary opening of the canopy and

may not provide sufficient time or resources for understory

development or growth of large trees. Higher intensity thinnings may be needed to facilitate future growth of overstory

trees and maintain a longer duration of open canopy conditions. Gap openings may also provide some of these benefits. Although initial assessment of vertical canopy structure

does not yet show signs of enhanced vertical structure in

thinned stands, retention of nondominant overstory species

does appear to be beneficial in preventing initial crown

simplification following thinning. Though more time is

needed to determine true effectiveness of thinning in acceleration of late-successional habitat, early evidence suggests

thinning may be an effective tool in management of young

Douglas-fir forests.

ACKNOWLEDGMENTS

This study was established by John Tappeiner, Loren

Kellogg, Brenda McComb, John Cissel, and James Mayo.

Cooperation comes from the USDA Forest Service, Pacific

Northwest Research Station; Willamette National Forest;

Bureau of Land Management; Oregon State University;

University of Oregon; and Cascade Center for Ecosystem

Management. We would like to thank Gody Spycher,

Maureen Duane, Lisa Ganio, and Steven Garman for assistance with YSTDS background information, data management, and analysis. 

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Research. 31: 1513-1525.

Trofymow, J.A.; Barclay, H.J.; McCullough, K. M. 1991. 

Annual rates and elemental concentrations of litter in

thinned and fertilized Douglas-fir. Canadian Journal of

Forest Research. 21: 1601-1615.

248
1 Hydrologist, 3 Ornithologist, 4 Research Ecologist; Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau,

AK 99801, USA; 2 Field Biologist, Skagit River System Cooperative, 11426 Moorage Way LaConner, WA 98257, USA. Email for corresponding author:

ajohnson03@fs.fed.us

Balancing Ecosystem Values Proceedings, Biodiversity

Observed Changes in Ground Saturation, Aquatic 

Invertebrate Densities, and Breeding Bird Populations 

Following Various Harvesting Intensities

Adelaide C. Johnson,1 Jacob Musslewhite,2 Toni L. De Santo,3 and Rick T. Edwards4

INTRODUCTION

The Alternatives to Clearcutting (ATC) project was

designed to determine ecological effects of different harvest

treatments occurring within old-growth forests (McClellan

et al. 2000, McClellan 2004). Here, we synthesize results

from the hydrology, invertebrate ecology, and avian ecology

components of the ATC project. We draw inferences about

the potential effects of alternative harvest patterns on physical and biologic interactions in headwater streams. We

summarize the individual study results and discuss the

potential effects of landslides caused by increased ground

saturation to downslope populations that use habitats influenced by sediment and associated accumulations of large,

woody debris (LWD). 

ABSTRACT

The effects of different harvest treatments on hillslope hydrology, avian populations, and aquatic invertebrates were

examined as part of the southeast Alaska Alternatives to Clearcutting project (McClellan et al. 2000). Here, we summarize

the response of hillslope soil hydrology, bird, and aquatic communities to the different cutting treatments. Through use of

groundwater-monitoring wells, we found that soil saturation on hillslopes increased significantly with harvest intensity at

one of two study locations following all cutting treatments. Increased soil saturation may decrease hillslope stability within

the harvested area. Aquatic invertebrate drift densities had coefficients of variation between 50 and 85 percent before harvest. Because of such variation, no harvest treatment effect was detected. Headwater streams can be a significant source of

aquatic and terrestrial invertebrates to downstream, fish-bearing reaches. However, detecting harvest effects will require

greater replication to reduce variability and increase statistical power. Birds associated with large trees were more abundant

in stands with higher tree retention at both study locations. Understory species reached maximum abundance at intermediate

harvest levels at Hanus Bay but did not differ at Portage Bay. Alterations in sediment delivery or hydrologic response may

change the pattern of sediment and woody debris storage and the functioning of aquatic and riparian avian communities 

further down the slope.

KEYWORDS: Forest management, ground saturation, aquatic ecology, forest passerine ecology.

249

This paper summarizes effects of forest harvest on (1)

ground saturation and hillslope stability, (2) transport (drift)

of macroinvertebrates and organic detritus in headwater

streams, (3) birds during the breeding season, and (4) potential changes in aquatic communities and riparian bird populations, assuming an increase in landslides. 

STUDY SITES, METHODS 

AND SUMMARY OF RESULTS

Preharvest ATC site evaluation was conducted at Hanus

Bay, Portage Bay, and Lancaster Cove; all within southeast

Alaska (see McClellan 2004, McClellan 2005 (in these

proceedings)). Post-harvest site evaluation was conducted

at Hanus and Portage Bay only, as Lancaster Cove has not
yet been harvested. Forests within the ATC study locations

are dominated by western hemlock (Tsuga heterophylla)

with smaller amounts of Sitka spruce (Picea sitchensis),

mountain hemlock (Tsuga mertensiana), yellow-cedar

(Chamaecyparis nootkatensis), western redcedar (Thuja

plicata), and red alder (Alnus rubra). Understory plant

species include red huckleberry (Vaccinium parvifloium),

Alaska blueberry (V. alaskaense), rusty menziesia

(Menziesia ferruginea), devil's club (Oplopanax horridus),

skunk cabbage (Lysichiton americanus), and false hellebore

(Veratrum eschscholtzii). Under natural conditions windthrow is the dominant forest disturbance (Harris et al. 1974,

Harris 1989, Nowacki and Kramer 1998), and there is little

fire (Noste 1979). Over the last 100 years at the ATC sites,

windthrow was not found to be a dominant disturbance

mechanism (Hennon and McClellan 2003). 

Nine harvest treatments were applied at each ATC study

site, ranging from uncut controls (100% retention) to clearcuts (0% retention). Additional treatments included (1)

evenly dispersed individual tree selection (ITS) with 75-

percent retention (75% ITS), (2) evenly dispersed ITS with

25-percent retention (25% ITS), (3) evenly dispersed ITS

with 5-percent retention (5% wildlife trees), (4) clearcut

harvest with aggregated reserves at 75-percent retention

(75% clumps), (5) aggregated reserves in a thinned matrix

at 25-percent retention overall (25% clumps), (6) gap harvest in a thinned matrix at 25-percent retention overall

(25% gaps), (7) gaps harvest in an uncut matrix with 75-

percent retention overall (75% gaps). Treatments were

unreplicated within each of the three sites. Sites were helicopter logged to ensure that disturbances were comparable

(McClellan 2000) and to minimize impacts to the ground

surface and understory vegetation. A detailed outline of

methodology, description of study locations can be found

in McClellan et al. (2002, 2004, 2005). 

Hydrology

The percentage of soil saturation within hillslope hollows

at Hanus Bay and Portage Bay was measured before and

after harvest with groundwater monitoring wells. One site

within each of the four uniform-harvest treatments, including an uncut control, 75% ITS, 25% ITS, and clearcut was

monitored with pressure transducers connected to data loggers. Data loggers, scanning every five seconds, recorded

mean water levels at 0.5 to 1.0 hour intervals. Temperature

gages were used to identify periods of freezing in the precipitation record. Rainfall was measured either at the site

or within 2.0 km of the site if the rain gage at the site was

not operating. 

Water levels were recorded from 1994 to1998 at Hanus

Bay and from 1996 to 2000 at Portage Bay from April

through November. The average maximum percentage of

saturation measured during a 48-hour storm period was

calculated for the seven wells at each site for 20 storms

before harvest and 20 storms after harvest. Harvest effects

were tested by using analysis of covariance for each of the

four treatments. Observations showed that soil saturation

levels on hillslopes differed significantly following all 

cutting treatments at Hanus Bay, but not at Portage Bay

(Johnson et al., in review). Use of an infinite slope stability

model (Sidle et al. 1985, Terzaghi 1943) indicates that

shallow soils at both study locations, with slopes generally

< 30° (58%), were not steep enough to be unstable under

the observed conditions (Johnson et al., in review). Because

many potential harvest sites, including ATC harvest units,

occur on steeper slopes than those selected for the hydrology

component of this study, we extrapolated the observed soil

saturation changes in clearcut sites to steeper slopes using

the slope stability model. With this model, we calculated

what slope and/or soil depth would result in destabilization

in a variety of pre-and post-treatment (saturation) cases. We

found that for 100-percent harvest, we estimated a 7-percent reduction in the factor of safety with forests having

slope gradients of 35° (70%) with soil depths of 1.25 m

(Johnson et al., in review).

Aquatic Ecology

Downstream transport (drift) of macroinvertebrates and

organic detritus in headwater streams located within all

ATC treatments was compared among streams at all three

sites before harvest. Post-harvest data were analyzed only

at Hanus Bay. Drifting invertebrates and detritus were captured in drift nets (250 μm mesh size) installed within the

stream channels in the spring, summer, and fall. Total stream

discharge and discharge through the net were measured and

data expressed as invertebrate mass per unit volume. 

Mean drift rates both pre- and post-treatment were 220

mg of invertebrate dry mass and 18 g of detritus per stream

per day with a range of 130 to 400 mg. There was no relation between harvest treatments and subsequent changes in

drift densities (Musslewhite and Wipfli 2004). However,

the mean coefficients of variation among streams were 85

percent for preharvest drift densities in the fall and 60 percent for preharvest drift densities in the spring. Based on

our understanding of small stream food webs, removing

trees to the streambank should impact the aquatic community and terrestrial insect inputs; however, such high natural

variation would mask all but the most extreme treatment

250
effects. Although no statistical tests were performed, a trend

toward an increase in the proportion of true flies (Diptera),

primarily midges (Chironomidae), and a decrease in the

proportion of mayflies (Ephermeroptera) was seen in the

lower retention treatments. With little research done on

insect drift in small southeast Alaska streams, the cause of

the large variation in drift is unknown. A better understanding of the fundamental controls on invertebrate growth and

production could allow for stratification of research sites

and reduced variance. Greater treatment replication would

increase the statistical power of the experiments but would

greatly increase monitoring costs. Future experiments should

have fewer treatments and more replication within each

treatment.

Avian Ecology 

A census of birds was taken by using the point-count

method (Ralph et al. 1995, Verner 1985) three times during

the breeding season (mid-May to early July; see McClellan

et al. 2000 for details). Because yearly variation within control sites was high for some species, we focused our comparisons within treatments rather than pre- to post-harvest. 

Species that use large trees for foraging or nesting

(chickadees (Parus hudsonicus, P. rufescens), brown creeper

(Certhia americana), golden-crowned kinglet (Regulus

satrapa), Pacific-slope flycatcher (Empidonax difficilis),

rufous hummingbird (Selasphorus rufus), Steller’s jay

(Cyanocitta stelleri), Townsend’s warbler (Dendroica

townsendi), varied thrush (Ixoreus naevius), woodpeckers

(Picoides pubescens, P. villosus, Colaptes auratus,

Sphyrapicus ruber)) were more abundant in stands with

higher tree retention (75% ITS, 75% gaps, 75% clumps,

control) than more heavily harvested treatments (clearcut,

5% wildlife trees, 5% gaps, and 25% clumps) at both study

locations; 25% ITS at Portage Bay; fig. 1). 

Species that nest or forage primarily in the understory

(dark-eyed junco (Juncus hyemalis), fox sparrow (Passerella

iliaca) hermit thrush (Catharus guttatus), orange-crowned

warbler (Vermivora celata), olive-sided flycatcher (Contopus

borealis), pine grosbeak (Pinicola enucleator) ruby-crowned

kinglet (Regulus calendula), Wilson’s warbler (Wilsonia

pusilla) winter wren (troglodytes troglodytes)) were more

abundant in several treatments receiving intermediate levels of harvesting (25% ITS, 25% gaps) than in either more

heavily harvested (clearcut, 5% wildlife trees) or lighter

harvested treatments (75% ITS, 75% gaps, 75% clumps),

but only at Hanus Bay (fig. 1). 

CONSERVATION OF AQUATIC 

AND AVIAN SPECIES 

Lessons Learned From Alternatives to Clearcutting 

The effects of harvest pattern varied widely among the

different ecosystem components and between the two locations. There was no evidence that transport of aquatic invertebrates and detritus varied among treatments. Groundwater

varied with treatment, but only at one study location. Birds

that use large trees differed at both study locations, but

understory birds were only affected at one study location.

Because treatments were unreplicated at each location, our

ability to separate treatment response from natural spatial

variation was limited, and there may have been effects

below the detection threshold. Conditions such as valley

location, total number of trees cut within catchments draining to wells, and the proximity of wells to the trees that

were cut varied widely among sites and may have influenced soil saturation more than the cutting treatments

(Johnson et al., in review). Bird and invertebrate densities

differ widely over space, and this variation is not well quantified with single treatments. Variation in time also limited

the power of our analyses. Interannual variation in bird and

invertebrate populations is large, and the pre- and post-harvest observation periods were too short to capture the full

range of natural annual variation. Additional replication at

the treatment level would increase statistical power and

enable us to detect more subtle responses. Longer pre- and

post-harvest sampling periods should also improve the

sensitivity of the analyses.

Physical and biological characteristics of watersheds

differ greatly within the Tongass National Forest, and have

been used to create a classification system of ecological

subsections (Nowacki et al. 2001). The ATC studies presented here confirm that this variation affects the response

of key ecosystem components to different harvest regimes.

We cannot generalize our findings Tongass-wide based on

only two locations. We cannot describe the total magnitude

of variation or its geographic pattern. Because we lack a

fundamental understanding of the natural variation in ecosystem responses across the Tongass, our ability to detect

management effects is compromised. More harvest locations encompassing a greater representation of watershed

types are necessary to determine whether the ecological

subsections defined in Nowacki et al. (2001) provide a useful context to predict ecosystem response to varying harvest

regimes. The potential for a landscape perspective to increase

our ability to predict management effects by stratifying

251
watersheds into ecologically similar units is promising, and

future research should be incorporated into that context.

Synthesis of Hydrology and Avian 

and Invertebrate Ecology

Although the ATC project did address the potential

impacts of some natural physical disturbances such as windthrow (McClellan 2004), it did not successfully assess disturbances from landslides. The groundwater study was

originally designed to determine the effects of harvest regime

on landslide potential, but the chosen study sites were not

steep enough to fail under any groundwater conditions.

Increased slope failure is one of the best documented effects

of past clearcutting (Bishop and Stevens 1964, O’Loughlin

and Zeimer 1982, Sidle 1985, Sidle et al. 1985, Swanston

1970, Swanston and Marion 1991, Wu et al. 1979), and the

downstream impacts can be profound. Although the hillslope

hollows monitored in this study were not steep enough to

generate landslides, it is inevitable that forest harvest will

continue within areas where soil depths and slopes do make

them vulnerable to failure if soil saturation increases.

Because landslides can greatly affect stream and riparian

habitats, and because some changes in soil saturation did

occur for all cutting alternatives at one of the study locations,

we will briefly discuss the potential consequences of slope

failures on stream and riparian habitats and the organisms

depending on them. 

Most landslides generated on steep deglaciated slopes

of southeast Alaska enter streams and deposit at the base 

of wide U-shaped valleys on slopes between 5 and 20

degrees (Gomi et al. 2001, Johnson et al. 2000, Swanston

and Marion 1991); slopes similar to those selected for ATC

study sites. Thus, although landslide initiation may occur in

steep, nonfish bearing reaches, the ultimate effects often

occur in lower gradient, fish-bearing reaches. The changes

in sediment and woody debris associated with landslide

deposition areas may change riparian vegetation type, LWD

distributions, and channel morphology; factors that influence food and habitats of mammals, birds, fish, and invertebrates in steep headwater streams. In second-growth

forest, more alder was found in stream channels impacted

by landslides (Johnson and Edwards 2001). Forests with a

higher percentage of alder export more aquatic invertebrates

to downstream reaches (Wipfli and Musselwhite 2004) and

have a higher nesting density of birds (De Santo et al., n.d.).

Mobility of the large wood was found to be associated

more with mass movements than with channel characteristics (Gomi et al., in review), therefore the number and size

of LWD jams may be influenced by landslides resulting

252

Figure 1a—Mean (± SE) abundance (number of detections

per 7850 m2) of avian species that use large trees for foraging or nesting in sites harvested in various silvicultural

patterns at Hanus Bay and Portage Bay. Species include

chickadees (Parus hudsonicus, P. rufescens), brown creeper

(Certhia americana), golden-crowned kinglet (Regulus

satrapa), Pacific-slope flycatcher, (Empidonax difficilis),

rufous hummingbird (Selasphorus rufus), Steller’s jay

(Cyanocitta stelleri), Townsend’s warbler (Dendroica

townsendi), varied thrush (Ixoreus naevius), and woodpeckers (Picoides pubescens , P. villosus, Colaptes auratus,

Sphyrapicus ruber).

Figure 1b—Mean (± SE) abundance (number of detections per 7850 m2) of avian species that nest or forage in

understory vegetation in sites harvested in various silvicultural patterns at Hanus Bay and Portage Bay. Species

include dark-eyed junco (Juncus hyemalis), fox sparrow

(Passerella iliaca), hermit thrush (Catharus guttatus),

orange-crowned warbler (Vermivora celata), olive-sided

flycatcher (Contopus borealis), pine grosbeak (Pinicola

enucleator), ruby-crowned kinglet (Regulus calendula),

Wilson’s warbler (Wilsonia pusilla), winter wren

(Troglodytes troglodytes).
from increased soil saturation on steeper slopes. Large

woody debris is important in retaining leaf litter and other

food inputs and in creating pools, which increase the quality

of habitat for fishes and invertebrates (Bryant et al., in

press; Woodsmith et al., in press).

Landslides can influence stream invertebrate community structure and drift rates. Although these links were

not made in the ATC study, studies within the Maybeso

Experimental Watershed, located in southeast Alaska, indicate how landslides and stream invertebrates are linked.

Streams in the Maybeso valley with at least one landslide

had significantly higher (t-test, p=0.035) mean invertebrate

drift densities than streams subjected to riparian logging

only (fig. 2). Drift densities in landslide-impacted Maybeso

streams were similar to those seen before harvest in ATC

streams in Hanus Bay, which contained streams with some

known landslide history (t-test, p=0.35). In addition, baetid

mayflies and chironomid larva, the most abundant taxa

found in ATC streams, are known to be early and abundant

colonizers following disturbance (Mackay 1992). Their

abundance in ATC drift samples before harvest may indicate

the adaptation of headwater stream communities to frequent

disturbance. 

Landslides may also impact riparian bird species.

Although streams were avoided during ATC avian censuses,

some bird species have positive associations with streams.

For example, the diet of the winter wren (Van Horne and

Bader, 1990) consists of many of the terrestrial and aquatic

invertebrates found at ATC headwater streams (Musslewhite

and Wipfli, 2004). Wrens tend to cluster their territories

around streams in southeast Alaska and British Columbia

(De Santo et al. 2003, Waterhouse et al. 2002, respectively)

with territory size inversely related to amount of stream

bank (De Santo et al. 2003). Wrens in southeast Alaska

often nest in downed wood or stream banks (30% of 175

nests in downed wood; 14% of nests in stream banks; 

De Santo et al. 2003 and unpublished data5) as they do 

in British Columbia (Waterhouse 1998, Waterhouse et al.

2002). In southeast Alaska, live trees and moss growing on

live trees were the foraging substrate most commonly used

by wrens, but most individuals also foraged on downed

wood, stumps, logs and slash (De Santo et al., n.d.). That

wren abundance in clearcuts was equal to or greater than

that in controls at both ATC sites may be because structural

forest attributes, including understory vegetation, moss

cover, and presence of small streams, are more influential

in determining the spatial distribution of wrens than forest

253

Figure 2—Mean macroinvertebrate drift densities of headwater streams with three different

disturbance histories. Streams are located in Hanus Bay, Alaska (“some known disturbance”)

and the Maybeso Experimental Forest, Alaska (“logging only” and “logging and landslides”).

Hanus Bay drift density data are from Musslewhite and Wipfli (2004); Maybeso drift density

data are from Wipfli and Musslewhite (2004). 

5 On file with M. McClellan, Pacific Northwest Research Station, 2270 Sherwood Lane, Suite 2A, Juneau, AK 99801, USA.
age (Waterhouse et al. 2002). Where harvest occurs in

landslide prone hillslopes, landsliding could alter the availability and quality of bird habitat.

In summary, impacts on slope stability or aquatic invertebrates occurred, but the power of the research to detect

impacts was limited by the lack of replication, high natural

variation, and short sampling interval. Impacts on some

avian species were evident, indicating a need for further

sampling to elucidate probable habitat associations and

effects of timber harvest. It is clear from this research that

data on the fundamental ecological properties of basins

across the large span of the Tongass National Forest are

needed to serve as a reference to quantify the impact of

various management practices. The ecological subsections

defined in Nowacki et al. (2001) may serve as a useful guide

to stratify rivers into similar classes and thereby partition

some of the variance encompassed by the studies described

here; however, a longer period of measurement will also be

needed to be able to detect treatment effects in the face of

high interannual natural variability.

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256
1 Assistant Professor and 2 Senior Faculty Research Assistant, Department of Forest Science, Oregon State University, Corvallis, OR 97331, USA. 

Email for corresponding author: luomad@fsl.orst.edu

Balancing Ecosystem Values Proceedings, Biodiversity

Results From Green-Tree Retention 

Experiments: Ectomycorrhizal Fungi

Daniel L. Luoma1 and Joyce Eberhart2

INTRODUCTION

Fungi profoundly affect nearly all terrestrial ecological

processes and events; accurate information on the fungal

component is required to adequately understand how ecosystems function (Trappe and Luoma 1992). When fungal

mycelia form particular associations with a host plant’s fine

roots, a symbiotic organ forms, called a mycorrhiza. Through

this structure the plant provides carbohydrates to the fungus,

ABSTRACT

The ecosystem effects of natural disturbances differ dramatically from those engendered by even-aged management

practices that emphasize commodity production. Because forest management activities can reduce ectomycorrhizal (EM)

fungus diversity and forest regeneration success, management approaches are needed to sustain these essential forests

organisms. We present selected results from experiments that test biodiversity assumptions behind current guidelines for

ecosystem management. We examine contrasts in structural retention as they affect biodiversity and sporocarp production 

of EM fungi—a functional guild of organisms well suited as indicators of disturbance effects on below-ground ecosystems.

Overstory removal significantly reduced EMF sporocarp production but, in contrast to the initial hypothesis, the effects

were not always proportional to basal area retained. The effect of spatial pattern of retention varied between retention levels

and mushroom and truffle sporocarp groups. Management implications include the need to address the conservation of rare

truffle and mushroom species in a manner that recognizes their different responses to forest disturbance. We also raise the

hypothesis that fire suppression may favor mushroom production over truffle production. Because fire seems to be important in the reproductive evolution of EMF, our results also add further impetus to the development of management plans

that seek to restore forest health from the effects of decades of fire suppression.

Experimental results suggest using dispersed green-tree retention in combination with aggregated retention to maintain

sporocarp production. Such a mix ameliorates disturbance effects and may maintain higher levels of sporocarp production

in the aggregates by reducing edge effects. It remains unclear how short-term reductions in sporocarp abundance will affect

EM fungus populations for future forests. After disturbance, spores are a form of legacy and key to enabling adaptations by

other species in the face of environmental change. Long-term silvicultural experiments are essential for monitoring trends 

in the EM fungus community.

KEYWORDS: Fungi, hypogeous, epigeous, mycorrhizae, biomass, diversity, disturbance.

257

which in turn facilitates uptake of nitrogen, phosphorus,

other minerals and water to the plant (Allen 1991, Marks

and Kozlowski 1973, Smith and Read 1997). The fungus

also protects plant roots from attack by pathogens and the

effects of heavy metal toxins, promotes fine root development, and may produce antibiotics, hormones and vitamins

useful to the plant (Smith and Read 1997). Mycorrhizal

associations are vital to the existence of most vascular

plants (Smith and Read 1997, Trappe 1987).
Availability of mycorrhizal fungi determines patterns 

of primary plant succession on new soils such as moraines,

fresh volcanic deposits, and mine spoils (Allen 1991,

Cázares 1992, Helm et al. 1999, Trappe and Luoma 1992).

Mycorrhizal fungi are associated not only with increased

plant productivity but also with developing community

diversity following disturbance (Allen et al. 1995, Cázares

1992). Mycorrhizal fungal species differ in their ability to

provide particular benefits to their hosts, and their presence

and diversity change during plant succession (Cázares

1992, Helm et al. 1996, Mason et al. 1983, Trappe 1977).

A diversity of mycorrhizal fungi is likely essential for successful shifts of geographic range by plants due to climate

change (Perry et al. 1990). 

The ectomycorrhiza type is characterized by a mantle 

of fungal hyphae encasing the root tips of the associated

plant. Ectomycorrhizae are characteristic of the Pinaceae

and Fagaceae which dominate most forests in the Pacific

Northwestern United States, and are required for survival

of these hosts in field soil (Trappe and Luoma 1992). We

are able to reasonably infer the mycorrhizal status of diverse

forest fungi by their placement in certain fungal genera

(Molina et al. 1992, Trappe 1962) despite the reservations

expressed by Arnolds (1991). Ectomycorrhizal fungi (EMF)

form a functional guild linking primary producers to soil

systems, are important in ecosystem response to disturbance

(Janos 1980, Perry et al. 1989), and may be sensitive indicators of environmental changes (Arnebrant and Söderström

1992, Arnolds 1991, Termorshuizen and Schaffers 1987,

Termorshuizen et al. 1990). Ectomycorrhizal fungi mostly

produce macroscopic sporocarps in the form of mushrooms

and truffles (epigeous or above-ground fruiting bodies and

hypogeous or below-ground fruiting bodies, respectively).

Sporocarps produce the spores that disseminate the species

and provide for genetic recombination within and among

populations. 

Forest Management

Studies from the Pacific Northwest indicate that forest

management activities can reduce ectomycorrhizal fungi,

forest regeneration success, and influence patterns of plant

succession (Amaranthus et al. 1994; Harvey et al. 1980a,

1980b; Waters et al. 1994; Wright and Tarrant 1958).

Development of management approaches to sustain these

essential organisms in forests has been hampered by a lack

of knowledge of EMF community structure, diversity, and

spatial and temporal variability across stands and landscapes. 

Many EMF species, especially those that produce truffles, are also important dietary items for vertebrates and

invertebrates: some small mammal species rely on them for

over 90 percent of their diet (Carey et al. 1999, Claridge et

al. 1996, Hayes et al. 1986, Jacobs 2002, Maser et al. 1978,

Maser et al. 1985). Truffle species diversity provides necessary nutritional diversity to the diet of mammal mycophagists

(see review by Luoma et al. 2003). Small mammals, in

turn, form important links in the trophic structure of forest

ecosystems as prey for raptors (e.g., owls and goshawks)

and mammalian carnivores (e.g., martens and fishers)

(Carey 1991, Fogel and Trappe 1978, Hayes et al. 1986,

McIntire 1984). 

Few studies have examined silvicultural effects on 

EMF sporocarp production (Colgan et al. 1999, Waters et

al. 1994). Although EMF sporocarps do not reveal as complete a picture of the below-ground EMF community as

root tip studies (Dahlberg et al. 1997, Gardes and Bruns

1996, Horton and Bruns 2001, Yamada and Katsuya 2001),

silvicultural effects on sporocarp production mirror the

effects found in root-tip studies: species diversity and community composition can change dramatically. Thinning

affects the composition and diversity of EMF in the stand

as well as the frequency of sporocarps (Carey et al. 2002,

Colgan et al. 1999, Waters et al. 1994). For example, stands

that were heavily thinned showed increased dominance by

one fungal species. Thinning also reduced truffle biomass,

frequency of truffles, and shifted overall species composition (Carey et al. 2002, Colgan et al. 1999). However, total

truffle biomass and frequency of sporocarps may recover

10 to 17 years after thinning, whereas shifts in species

dominance persist longer (Waters et al. 1994).

Green-tree retention, the practice of leaving live, structurally-sound, large trees in a stand after extracting timber,

is an alternative forest management method designed to

accelerate the development of late-successional forest characteristics in young, managed stands (Aubry et al. 1999).

The Demonstration of Ecosystem Management Options

(DEMO) experiment is a long-term study designed to examine the effects of different levels and patterns of green-tree

retention on multiple forest attributes (see Aubry et al. 1999).

Studies of disturbance effects on the below-ground ecosystem are relatively rare. These studies are critical to forest

managers seeking to incorporate basic ecological knowledge into forest management policies and practices. Here

we focus on initial results from an experiment that tested

some of the assumptions behind the current guidelines for

ecosystem management as they affect a functional guild of

organisms (EMF) that are well suited as indicators of disturbance effects on the below-ground ecosystem. Detailed

reporting of the DEMO fungi study can be found in Luoma

et al. (2004).

258
The DEMO Experiment

The objective of the DEMO fungi study was to compare

pre- and post-treatment standing crop biomass of EMF

sporocarps within no harvest, 75-percent, 40-percent (dispersed and aggregated), and 15-percent (dispersed and

aggregated) retention treatments. The DEMO experiment

replicated six green-tree retention treatments in six geographic locations (Aubry et al. 1999). The treatments consisted of four levels of live tree retention (15, 40, 75, and

100 percent of existing live-tree basal area), with two patterns of retention, aggregated (A) and dispersed (D), applied

to the 15- and 40-percent retention treatments. The aggregated pattern consisted of residual trees retained in clumps

of about 1 ha and the dispersed pattern has residual trees

homogeneously dispersed throughout the unit. For the 75-

percent retention treatment, all of the harvest occurred in

approximately 1-ha patches dispersed throughout the unit.

Fungal sporocarp sampling was limited to 3 blocks. 

Study Area

General environmental characteristics of the sites are

described by Halpren et al. (1999). The Butte block is

located on the Gifford Pinchot National Forest in southwestern Washington. The Dog Prairie and Watson Falls

blocks are located on the Umpqua National Forest in southwestern Oregon. Prior to harvest, all blocks were dominated

by Pseudotsuga menziesii (Mirb.) Franco. The importance

of other tree species varied by block (Halpren et al. 1999). 

RESULTS

Luoma et al. (2004) found that total fall biomass exceeded

total spring biomass for both epigeous and hypogeous

sporocarps except in the Watson Falls block where spring

biomass of Gautieria was a major contribution to greater

spring hypogeous sporocarp biomass. In particular, total

fall mushroom biomass decreased significantly in the 40-

percent aggregated, 15-percent dispersed, and 15-percent

aggregated treatments as compared to the other treatments

(fig. 1). No treatment effect was detected on the fall mushroom standing crop in the 40-percent dispersed treatment

(fig. 1). Total fall truffle biomass was significantly reduced

in the 40-percent aggregated, 15-percent dispersed, and 15-

percent aggregated treatments as compared to the control,

75-percent aggregated, and 40-percent dispersed treatments

(fig. 2). No treatment effect was detected on the fall truffle

standing crop in the 40-percent dispersed treatment (fig. 2).

DISCUSSION

Relevance to Ecosystem Management

Standing crop data are useful to interpret the role of

fungal species as a food source for animals or the energy

expanded in an ecosystem for species reproduction. Standing

crop of hypogeous sporocarps may underestimate actual

sporocarp biomass productivity because animals utilize a

proportion of the fruiting bodies (Luoma et al. 2003). The

degree of underestimation is most pronounced at periods of

low productivity, when consumptive pressure on the available food resource is proportionally high (North et al. 1997).

When both epigeous and hypogeous species are simultaneously assessed, new understanding of overall diversity

phenomena emerges. For example, the more equable biomass

distribution of hypogeous sporocarps compared to epigeous

between spring and fall (Luoma et al. 2004, Smith et al.

259

Figure 1—Mean total ectomycorrhizal mushroom standing crop biomass

for the fall samples from three DEMO blocks. Standard errors are indicated

by vertical bars. Among-treatment comparisons were derived from multiple

analysis of variance, repeated measures contrasts of the time * treatment

interaction using transformed data. Treatments (see methods) without a

shared horizontal bar above them are significantly different at p ≤ 0.1

(adapted from Luoma et al. 2004, used with permission). D = dispersed

retention; A = aggregated retention.

Figure 2—Mean total truffle standing crop biomass for the fall samples from

three DEMO blocks. Standard errors are indicated by vertical bars. Amongtreatment comparisons were derived from multiple analysis of variance,

repeated measures contrasts of the time * treatment interaction using transformed data. Treatments (see methods) without a shared horizontal bar

above them are significantly different at p ≤ 0.1 (adapted from Luoma et al.

2004, used with permission). D = dispersed retention; A = aggregated

retention.
2002) has important implications to mycophagous mammals. Fungal diversity in the diet of such animals appears

to be nutritionally important (Claridge et al. 1999, Johnson

1994, Maser et al. 1978). Clearly, animals that depend on

fungi as major food items (Fogel and Trappe 1978, Luoma

et al. 2003) could not rely on epigeous fungi for diet diversity over the spring. Quite possibly, the decline in populations of some mycophagous animals could relate to decline

in diversity of the fungal populations due to habitat disturbance (Claridge et al. 1996, Pyare 2001). Results from the

DEMO study show that truffle genera important in the diets

of small mammals were significantly affected by the treatments (Jacobs 2002).

Maintenance of EM fungal diversity is important for

ecosystem health and resilience (Amaranthus 1997;

Amaranthus and Perry 1987, 1989; Perry et al. 1990).

Disturbance, whether natural or human caused, can 

drastically alter populations of EM fungi (Amaranthus et

al. 1990, 1994, 1996; Colgan 1997; Pilz and Perry 1984;

Schoenberger and Perry 1982). 

The Secotioid Syndrome

Some sporocarps have morphology that is intermediate

between truffles and mushrooms. Such sporocarps have

been referred to as “secotioid” (Singer 1958). In addition to

epigeous secotioid taxa, Thiers (1984) included all trufflelike taxa in his analysis of the “secoitioid syndrome.” He

proposed that in the Mediterranean and semi-arid climates

of the western United States, high summer temperatures

combined with extended drought stress were primary drivers in the evolution of hypogeous sporocarp formation (i.e.,

the truffle form). Bruns et al. (1989) documented that such

morphological divergence (from mushroom to truffle) can

proceed relatively rapidly, possibly as a result of selective

pressures on a small number of developmental genes. Hibbett

et al. (1994) present a case in which a simple secotioid

phenotype, arising from a mutation at one locus, has persisted over a wide geographic range in wet environments

that presumably do not exert the selective pressures that

drive the secotioid syndrome toward evolution of more

strongly sequestrate (Trappe et al. 1992) sporocarps. Baura

et al. (1992) speculate that such mutations will not persist

long in a population. Kretzer and Bruns (1997) found that

secotioid forms of the important EM mushroom genus

Suillus evolved at least twice and have persisted for evolutionarily significant periods of time over a wide range of

summer-dry habitats in the western United States. They

noted that the selective forces that favor a secotioid lineage

were unclear.

We propose that results from Luoma et al. (2004) represent

the first experimental evidence to support Thiers’ hypothesis

(1984). Even the relative small (1 ha) gaps created in the

75-percent aggregated retention treatment significantly

reduced fall production of EM mushrooms in the surrounding uncut forest. Those same gaps, however, did not significantly reduce truffle production. The formation of gaps

likely influenced the thermal properties, humidity, and

evapotranspiration of the remaining intact forest (e.g., Zheng

and Chen 2000). Based on these results, we extend Thiers’

hypothesis to encompass the influence of fire in the broader

context of forest disturbance in the summer-dry climates 

of the western United States. Fire is an important agent 

for producing the patterns of forest fragmentation (e.g.,

Heyerdahl et al. 2001) that would select for hypogeous

sporocarp production via the “secotioid syndrome.”

CONCLUSIONS

Even though green-tree retention can preserve ectomycorrhiza diversity (Stockdale 2000), sporocarp production

and EM species richness was significantly reduced at all

levels of retention except the control. These effects, however, differed by season and treatment (Luoma et al. 2004).

The DEMO study demonstrated the importance of pretreatment sampling. Experimental units within blocks were

intended to be as similar as possible in overstory vegetation

and site characteristics (Aubry et al. 1999), yet pretreatment

results showed that uniformity of fungal populations in

forests based on stand structure alone can not be assumed

(see also Cázares et al. 1999). 

Management implications include the need to address

the conservation of rare truffle and mushroom species in a

manner that recognizes their different responses to forest

disturbance. We also raise the hypothesis that fire suppression may have favored mushroom production over truffle

production. Because fire seems to be important in the reproductive evolution of EMF, our results also add further

impetus to the development of management plans that seek

to restore forest health from the effects of decades of fire

suppression (Agee 1997).

Luoma et al. (2004) also found that overstory removal

significantly reduced EMF sporocarp production but, in

contrast to their initial hypothesis, the effects were not

always proportional to basal area retained. The effect of

spatial pattern of retention varied between retention levels

and mushroom and truffle sporocarp groups. Though not

260
directly studied in the DEMO experiment, Luoma et al.

(2004) concluded their results supported the use of dispersed green-tree retention in combination with aggregated

retention when maintenance of sporocarp production is a

goal. Continuing study of retention level and spatial pattern

relationships is important for development of scientifically

sound silvicultural techniques for use in the pursuit of 

science-based forest management. 

ACKNOWLEDGMENTS

This research is a component of the Demonstra-tion of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of

Washington. 

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264
1 Research Wildlife Ecologist, Oregon State University, Department of Forest Science, Corvallis, OR 97331, USA. Email for corresponding author: 

chris.maguire@oregonstate.edu

2 Wildlife Research Assistant, Oregon State University, Department of Forest Science, Corvallis, OR 97331, USA

3 Associate Dean and Wildlife Ecology Professor, University of Washington, College of Forest Resources, Box 352100, Seattle, WA 98195, USA

4 Wildlife Ecology Graduate Student, University of Washington, College of Forest Resources, Box 352100, Seattle, WA 98195, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Green-Tree Retention in Managed Forests: 

Post-Harvest Responses of Salamanders

Chris C. Maguire,1 Tom Manning,2 Stephen D. West,3 and Robert A. Gitzen4

INTRODUCTION

Consideration of biodiversity goals along with timber

production recently intensified in managed forests in the

Pacific Northwest (PNW) of the United States as concerns

grew over the steady conversion of once abundant, structurally diverse, old-growth forests into single-species, evenaged, short-rotation plantations. Many land managers hoping

to conserve and enhance biological diversity in production

forests, are using a range of uneven-aged management

options to promote complex forest structure. However, the

effectiveness of these options in conserving forest-associated

species are poorly studied. Thus, the data necessary to help

ABSTRACT

Salamanders often are proposed as indicators to monitor ecological ramifications of forest management practices because

of their high site tenacity and environmental sensitivity. In this study, we examined post-treatment responses of salamanders

to variation in the level and pattern of live trees retained during harvest within the Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco) region of the Pacific Northwest of the United States. Forested units within six blocks were subjected to six different

treatments ranging from 100- to 15-percent basal area retention in dispersed or aggregated patterns. When analyzed with

randomized block ANOVA, salamander capture trends associated with the level and pattern of basal area retained were not

evident up to 2 years after harvest for any of the four most abundantly captured species: ensatina (Ensatina eschscholtzii),

western red-backed salamander (Plethodon vehiculum), northwestern salamander (Ambystoma gracile), and rough-skinned

newt (Taricha granulosa). However, habitat analyses employing multiple regression indicated that salamanders were encountered most frequently when coarse woody debris (CWD) volume and/or herb cover were high; tree basal area was of 

secondary or limited importance in predicting salamander numbers. Results suggest that salamanders respond to altered

environmental conditions induced by forest management that are not directly tied to basal area. Additionally, because we

have the silvicultural tools to manipulate forest ground conditions, it should be possible to manage structural features important to salamanders while also extracting timber. 

KEYWORDS: Basal area retention, forest structure, Pacific Northwest, salamanders, tree harvest.

265

direct selection of appropriate management scenarios conducive to both timber production and biological diversity

are largely lacking.

In 1992, the Demonstration of Ecosystem Management

Options (DEMO) study was initiated by the U.S. Congress

in the Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

region of the PNW to examine ecological consequences of

harvests where live trees are retained in different levels and

patterns (Halpern and Raphael 1999). Animal groups studied in this large-scale, long-term experiment are terrestrial

and arboreal small mammals, bats, birds, and salamanders.

This paper focuses on initial DEMO results obtained for

salamanders.
Because salamanders are abundant in many forest ecosystems (Hairston 1987, Merchant 1972, Pough et al. 1987)

and may have biomass comparable to birds and mammals

(Burton and Likens 1975), they likely contribute significantly to natural forest processes. Additionally, their narrow

habitat tolerances (Blaustein 1994) may allow them to

respond rapidly to changing environmental conditions. Many

species also have limited mobility and high site tenacity

(Welsh 1990). Collectively, these features may make salamanders a suitable indicator species group for monitoring

ecosystem consequences of forest management (McLaren

et al. 1998, Welsh and Droege 2001).

In this study, we hypothesized that salamanders would

respond in three ways to partial forest harvests that alter

the level and pattern of green-tree retention. First, because

salamanders are forest-dwellers, we projected that their

numbers would correlate with tree basal area, i.e., abundance would decrease with increasing harvest intensity.

Second, if salamander abundance does correlate with tree

basal area, then harvest level rather than harvest pattern

should have a greater impact on salamander numbers within

a standardized area. Finally, because terrestrial salamanders

largely reside in and on the ground, we predicted that their

numbers would relate more closely to forest floor characteristics than to tree basal area, particularly immediately postharvest when disrupted ground conditions resulting from

logging are most pronounced.

METHODS

Study Area and Design

Six harvest treatments within low- to mid-elevation

(range: 244 to 1614 m) Douglas-fir dominated forests provided the framework of the study: 100-percent basal area

retention (control); 75-, 40-, and 15-percent aggregated

retention (75%A, 40%A, 15 %A); and 40 and 15 percent

dispersed retention (40%D, 15%D). In 75%A units, harvest

areas were restricted to three 1-ha patches; in 40%A units,

trees were retained in five 1-ha patches; in 15%A units,

trees were retained in two 1-ha patches. Treatments were

replicated six times across four blocks in western Washington

(Capitol Forest, Butte, Paradise Hills, Little White Salmon)

and two blocks in western Oregon (Watson Falls, Dog

Prairie) for a total of 36, 13-ha treatment units. Units were

harvested in 1997 and 1998. See Aubry et al. (1999) and

Lehmkuhl et al. (1999) for additional study site and treatment details.

Forest Structure and Salamander Sampling

Sampling in each unit was based on a permanent 9 x 7 or

8 x 8-point grid with 40-m spacing between adjacent points.

Vegetation characteristics were measured at approximately

half the grid points in each of the treatment units both before

and after harvest. Variables examined in this study included:

tree basal area (≥5.0-cm d.b.h.), percentage of herb cover

(100 percent maximum; <1-m height potential), percentage

of tall shrub cover (100 percent maximum; >1-m height

potential), and coarse woody debris (CWD) volume (≥10-

cm diameter). Additional information on vegetation sampling is published in Halpern et al. (1999) and McKenzie 

et al. (2000).

We placed one 72- x 15-cm pitfall trap at each grid point

on each unit to sample salamanders for 2 years both before

and after harvest. Traps were open approximately 4 weeks

during the months of October and November (sampling

period range: 26 to 32 days) when ground surface activity

of salamanders is high due to fall rains (Olson 1999). All

captured salamanders were identified to species, and live

individuals were temporarily removed from the units to

prevent multiple sampling of individuals within a trapping

season.

Statistical Analyses

For each four-week trapping session, salamander samples

were standardized to number of individuals captured per

1000 trap nights per unit. To examine effects of retention

treatments on salamander abundance, we used randomized

block one-way ANCOVAs on differences between means

of the two before and after harvest samples. Tree basal area

and elevation were used as covariates. Differences among

means were tested with Tukey’s Studentized Range (HSD)

Test. One-way ANOVAs were used to test for differences

in forest characteristics among treatments both before and

after harvest, and pre- and post-harvest correlations among

forest characteristics also were determined. Additionally,

we used multiple-regression analyses with blocks as indicator variables to identify which of the four forest features

sampled correlated with mean post-harvest salamander captures. We also included elevation as a possible predictor

variable. Data were transformed for analysis when necessary and analyses were performed using SAS/STAT software (SAS Institute Inc. 1989). Significant differences

were tested at α = 0.1 except for the HSD Test (α = 0.05).

RESULTS AND DISCUSSION

Preharvest treatment means (N = 6) for tree basal area,

percentage of herb cover, percentage of tall shrub cover,

and CWD volume all were similar among treatment units

(p-values ≥ 0.38; table 1). Herb cover decreased with

increasing basal area before harvest (r = -0.53, p < 0.001),

most likely as a consequence of reduced light availability

266
on the forest floor as tree crown cover increased with

increasing basal area (e.g., Bailey et al. 1998). Conversely,

herb cover decreased with decreasing basal area after harvest (r = 0.38, p = 0.02) when elevated timber removal

resulted in more extensive ground disturbance (Halpern and

McKenzie 2001). Although tall shrub cover had positive

correlations with herb cover both before (r = 0.48, p = 0.003)

and after harvest (r = 0.49, p = 0.002), it did not mimic basal

area trends (p-values > 0.60) as did herb cover. CWD volume had a marginally significant negative relationship with

herb cover after harvest (r = -0.3, p = 0.07), but no apparent trends with basal area (preharvest: r = -0.13, p = 0.46;

post-harvest: r = -0.21, p = 0.22).

Eight salamander species were encountered during the

study, but no species was captured in all units before harvest, and few were captured in all six replicates of a treatment after harvest (table 2). Three species were found

exclusively in one unit each following harvest: Cascade

torrent salamander (Rhyacotriton cascadae), Pacific giant

salamander (Dicamptodon tenebrosus), and clouded salamander (Aneides ferreus). The western red-backed salamander (Plethodon vehiculum) was found only on the low

elevation units of Capitol Forest. Additionally, control units

had from 42 percent fewer captures to 99 percent more

captures in the post-harvest period compared with preharvest (table 3). These data highlight the large temporal, 

spatial, and geographic variability associated with the distribution of salamanders and their aboveground activities

even in the absence of forest management. This variability

significantly complicates interpretation of salamander abundance estimates and forest management impacts (Pechmann

et al. 1991).

Trapping resulted in the capture of 3657 individual salamanders at the rate of 13.8 captures per 1000 trap nights

before harvest and a similar rate of 14.3 captures per 1000

trap nights after harvest (range: 0 – 82.2 captures per 1000

trap nights per treatment unit). Randomized block ANCOVA did not detect a significant difference in capture rate

change across treatments before or after harvest (p = 0.48),

and captures did not differ between aggregated and dispersed units at the same harvest level. Only three of the

eight salamander species encountered were found in sufficient numbers and in sufficiently wide distributions to analyze species captures with ANCOVA. These species were

ensatina (Ensatina eschscholtzii), northwestern salamander

(Ambystoma gracile), and rough-skinned newt (Taricha

granulosa) (table 3). There were no significant treatment

effects for any of these species on the change in capture

rates before and after harvest (p-values > 0.21), including

no capture differences between dispersed and aggregated

treatments. Collectively, these results caused us to reject

the hypotheses that salamanders would decrease in abundance with increasing harvest intensity, and that harvest

level would have a greater impact on salamander numbers

than harvest pattern.

Salamanders may not have exhibited immediate postharvest responses to basal area reduction for several reasons. Because of high site tenacity, small home ranges,

fossorial tendencies, and high life potential (up to several

decades; Bowler 1977), salamander populations may have

delayed aboveground responses to forest management

activities (Bunnell et al. 1997). High temporal and spatial

capture variability of salamanders also may reduce our

ability to detect significant differences due to treatments.

267

Table 1—Pre- and post-harvest means for structural characteristics of 13-ha forest units 

treated to different levels and patterns of tree basal area retention

Forest characteristics

BA (m2/ha) Herbs (%) Tall shrubs (%) CWD (m3/ha)

Treatments Pre Post Pre Post Pre Post Pre Post

100% 66.5 68.1 36.2 33.9 21.3 21.0 150.6 145.8

75%A 63.7 51.4 37.7 33.0 26.5 17.7 184.3 157.8

40%D 61.8 29.5 36.4 22.5 24.4 11.4 159.4 114.6

40%A 69.0 27.1 32.8 19.7 30.0 20.4 191.6 151.6

15%D 67.5 11.8 30.1 14.6 26.6 9.8 157.0 141.3

15%A 72.0 11.5 31.4 13.4 23.3 12.3 293.2 265.0

Note: BA = tree basal area; Herbs = cover of vegetation with <1-m height potential; Tall shrubs = cover of vegetation with 

>1-m height potential; CWD = volume of coarse woody debris with ≥10-cm diameter. Treatments include: 100% basal 

area retention; 75, 40, and 15% aggregated retention (75%A, 40%A, 15%A); and 40 and 15% dispersed retention (40%D, 

15%D). Each treatment was replicated in six blocks in Douglas-fir dominated forests in western Washington and western 

Oregon.
Additionally, treatments in the DEMO study were based 

on percentage of basal area reductions rather than absolute

basal areas. Thus, variability in unit basal areas prior to

harvest was maintained among units within treatments following harvest. The range of absolute basal area conditions

within treatment units likely contributed to the variability

in salamander captures among replicates within treatments. 

Results from the regression analyses that focused on

captures and absolute measures of forest structure suggest

that salamander captures reflect variation in forest features

beyond basal area. Regression analysis of post-harvest salamander captures (per 1000 trap nights) versus forest structural features resulted in significant correlations (p-values

≤ 0.0001) for the four most abundant species. Captures for

both the western red-backed salamander and the roughskinned newt were positively correlated with herb cover

(r2 = 0.95 and 0.62, respectively). The northwestern salamander also was captured more frequently as herb cover

increased, but this species had a negative relationship with

tree basal area (r2 = 0.66). Ensatina had positive correlations

with both basal area and CWD volume (r2 = 0.85). When

all species were examined together, CWD volume was the

forest characteristic of those measured that best predicted

total salamander captures (r2 = 0.78, p = 0.0001). Tall shrub

cover was not a significant correlate for any of the four most

abundant salamander species analyzed individually or for

salamanders as a group.

The regression analyses also indicated that combinations of tree basal area, herb cover, and CWD volume were

better able to predict captures of the fully-terrestrial salamanders, ensatina and western red-backed salamander, than

captures of the aquatic breeders, northwestern salamander

and rough-skinned newt (r2 ≥ 0.85 and 0.66, respectively).

Whereas the presence of aquatic species on land is tied

foremost to the presence of nearby aquatic breeding areas

(Gibbons and Semlitsch 1981), terrestrial salamanders are

impacted by events on land throughout their entire lives.

This tighter link with conditions on land suggests that terrestrial salamanders may better reflect changing forest 

conditions than aquatic species. Yet, for all species in this

study, ground cover in the form of CWD or herbaceous

vegetation was a significant habitat component. Coarse wood

debris and herbs appear to provide salamanders with cover,

ameliorate microclimatic conditions, and serve as a source

of and/or foraging surface for arthropod prey (Butts and

McComb 2000, Jaeger 1978). Basal area, however, was a

poor correlate of the forest structures examined in the study

in the first few years following harvest; this probably resulted

268

Table 2—The percentage of 13-ha forest treatment units (N = 6 units per treatment) in which individual 

salamander species were trapped before and after harvest

Post-harvest Units

All units

Species preharvest 100% 75%A 40%D 40%A 15%D 15%A

Ensatina (T) 86.1 100.0 100.0 83.3 83.3 100.0 100.0

(Ensatina eschscholtzii)

Western red-backed salamander (T) 22.2 16.7 16.7 16.7 16.7 16.7 16.7

(Plethodon vehiculum)

Northwestern salamander (A) 83.3 83.3 66.7 100.0 66.7 83.3 100.0

(Ambystoma gracile)

Rough-skinned newt (A) 63.9 66.7 66.7 33.3 66.7 83.3 66.7

(Taricha granulosa)

Cascade torrent salamander (A) 8.3 0.0 16.7 0.0 0.0 0.0 0.0

(Rhyacotriton cascadae)

Long-toed salamander (A) 13.9 27.8 16.7 16.7 16.7 0.0 16.7

(Ambystoma macrodactylum)

Pacific giant salamander (A) 13.9 0.0 0.0 0.0 16.7 0.0 0.0

(Dicamptodon tenebrosus)

Clouded salamander (T) 27.8 0.0 0.0 0.0 0.0 0.0 16.7

(Aneides ferreus)

Note: Basal area retention treatments in Douglas-fir dominated forests are identified in table 1. Salamander species followed by (A) are those that

breed in water and have both aquatic and terrestrial phases; species followed by (T) breed and live their entire lives on land. Species are ordered 

from most to least abundant before harvest.
from harvest activity-induced forest floor disturbance

(Halpern and McKenzie 2001). Consequently, captures of

individual salamander species also correlated poorly with

tree basal area after harvest because salamanders are more

impacted by forest structural features near the ground. These

results support our third hypothesis concerning close salamander relationships with forest floor structure.

Results of this study suggest that salamanders are able

to tolerate major habitat disruptions resulting from harvest,

at least during the immediate post-treatment years. They

also respond to altered environmental conditions induced

by forest management that are not directly tied to basal

area. Because salamander captures, and presumably salamander populations, are significantly correlated with CWD

and herbaceous vegetation, it should be possible to harvest

timber while simultaneously managing forest floor habitat

features important to salamanders during forest regeneration.

ACKNOWLEDGMENTS

We thank the following individuals for their numerous

and varied contributions to this study: R. Abbott, K. Aubry,

R. Bigley, C. DeYoung S. Evans, D. Fox, J. Franklin, C.

Halpern, F. Henchell, D. Hibbs, M. Huso, K. Kelsey, D.

Liguori, D. Maguire, B. McComb, K. McDade, D.

McKenzie, J. Nakae, L. Norris, C. Peterson, D. Phillips, R.

Ribe, D. Shaw, T. Smith, G. Spycher, T. Stout, A. Stringer,

R. Thompson, E. Tompkins, J. White, B. Woodward, and

E. Zenner. This research is a component of the Demonstration of Ecosystem Management Options (DEMO) study.

Funds were provided by the USDA Forest Service, PNW

Research Station to Oregon State University and to the

University of Washington. Salamanders were captured under

Oregon Department of Fish and Wildlife and Washington

Department of Wildlife scientific taking permits, and with

Institutional Animal Care and Use Committee (IACUC)

approval at both Oregon State University and the University

of Washington.

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269

Table 3—Mean salamander captures and the percent distribution of captures across basal area retention treatments before and after

harvest

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1 Hayes Professor of Silviculture and 2 Faculty Research Assistant, Department of Forest Science, Oregon State University, Corvallis, OR 97331, 

USA. Email for corresponding author: doug.maguire@oregeonstate.edu

3 Research Professor of Forest Ecology, College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

4 Research Wildlife Biologist, USDA Forest Service, Pacific Northwest Research Station, Olympia, WA 98512, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Fate of Taxa After Variable-Retention Harvesting 

in Douglas-fir Forests of the Northwestern United States

Douglas A. Maguire,1 Sean Canavan,2 Charles B. Halpern,3 and Keith B. Aubry4

INTRODUCTION

Variable-retention harvesting may enable economically

viable timber extraction while maintaining elements of biological diversity that might be lost if stands were clearcut

(Franklin et al. 1997). Retained trees are intended to serve

at least three functions: (1) maintain forest-dwelling taxa

until a new stand is established, (2) provide forest connectivity in harvested areas, and (3) enhance the structural

diversity of the future stand. Federal forest-management

ABSTRACT

Regeneration harvests that retain differing proportions of initial stand basal area have been proposed as an alternative to

clearcutting as a way to conserve biological diversity in forests. Variable-retention harvesting has been mandated on federal

lands in the Pacific Northwest region of the United States, but its efficacy for maintaining species diversity is largely untested. The DEMO (Demonstration of Ecosystem Management Options) study was initiated to evaluate the effects of differing

levels and patterns of retained trees on various groups of forest-dwelling organisms. Six treatments were implemented in

Douglas-fir forests at each of six locations (blocks) in western Washington and Oregon: 100-percent retention (control), 75-

percent aggregated retention (three 1-ha gaps cut within the treatment unit), 40-percent dispersed retention (regular distribution of residual trees), 40-percent aggregated retention (five uncut 1-ha forest aggregates), 15-percent dispersed retention

(regular distribution of residual trees), and 15-percent aggregated retention (two uncut 1-ha forest aggregates). Herbs, ectomycorrhizal sporocarps (mushrooms and truffles), canopy arthropods, amphibians, forest-floor small mammals, and breeding

birds were sampled before and soon after treatments were implemented. In this paper, we analyze the probability that taxa

detected before treatment were detected after treatment. ANCOVA suggested that the probability of confirming the persistence of mushroom, truffle, and bird taxa in each unit after treatment was directly related to the proportion of live trees

retained. Orthogonal contrasts indicated that most treatment effects were attributable to differing levels of retention, although

fewer bird species were detected after harvest in dispersed-retention treatments compared to aggregated-retention treatments.

Regression analysis with continuous stand structural variables also indicated that lower residual stand densities resulted in 

a significantly greater probability of detection failure for all groups, and that additional variation in the response of canopy

arthropods and birds was accounted for by covariates representing differences in vertical structure. Further assessment of

both the loss of initial taxa and the appearance of new taxa will be conditioned on possible changes in detection probabilities

and known and hypothesized habitat relationships or trophic interactions. 

KEYWORDS: Variable retention, biodiversity, timber harvest, crown area profile, stand structure.

271

strategies in the northwestern United States (the Northwest

Forest Plan) specify the retention of live trees in at least

15 percent of each harvest unit, with at least 70 percent of

retention in forest aggregates 0.2-1.0 ha in size (Tuchman

et al. 1996). To date, few studies have been conducted to

evaluate the extent to which different levels or patterns of

retention maintain late-seral forest species in regenerating

stands. The DEMO (Demonstration of Ecosystem Management Objectives) study was established in the mid-1990s 

to address this knowledge gap with a controlled harvest
272

experiment implemented by a multidisciplinary team of

researchers and forest managers (Aubry et al. 1999). 

Variable-retention treatments may fail to maintain forest

biodiversity for at least two reasons: local extirpation of

species or reduction of populations below viable levels. In

this paper, we focus on the former by determining which

taxa were detected prior to variable-retention harvest treatments, then assessing their apparent fate several years after

harvest. There are potential limitations to this kind of analysis. Simple sampling error may confound our assessments

of the presence or absence of taxa both before and after

harvest. In addition, variable-retention harvests create posttreatment environments that may differ substantially in composition and structure from pretreatment environments.

Consequently, apparent treatment effects on the persistence

of taxa may reflect local extirpations, or may be due to sampling error or changes in detection probabilities, even if

populations remain stable (Gu and Swihart 2004). In this

paper we limit our analysis to testing for (1) the effect of

retention level and spatial pattern on the probability of detecting the persistence of taxa several years after harvest, and

(2) the effects of residual stand structural parameters on the

probability of detection. Future work will address the causal

mechanisms of treatment effects and the likelihood that our

results reflect local extirpations vs. alternative explanations. 

METHODS

Six study locations (blocks) were selected to represent 

a diversity of mature forests (65-170 years) dominated by

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco); Aubry

et al. 1999). Two blocks were located in the Cascade Range

in central Oregon, three in the Cascade Range in southern

Washington, and one in the Coast Range in southwestern

Washington. Elevations ranged from ca. 200-1700 m and

slopes varied from gentle to steep, with a broad range of

aspects represented (table 1). Three blocks (Butte, Capitol

Forest, and Watson Falls) were in the western hemlock

(Tsuga heterophylla) forest zone, one (Little White Salmon)

was in the grand fir (Abies grandis) zone, one (Dog Prairie)

was in the white fir (A. concolor) zone, and one (Paradise

Hills), was in the Pacific silver fir (A. amabilis) zone

(Franklin and Dyrness 1973). At each block, five harvest

treatments and a control were randomly assigned to 13-ha

experimental (treatment) units. Treatments differed by the

level (percentage of initial basal area) and spatial pattern

(dispersed vs. aggregated) of retained trees as follows: (1)

100 percent: 100-percent retention (control); (2) 75%A:

75-percent aggregated retention (three circular, 1-ha patch

cuts in an uncut matrix); (3) 40%D: 40-percent dispersed

retention (uniform spatial distribution of residual trees);

(4) 40%A: 40-percent aggregated retention (five circular 1-

ha forest aggregates in a cut matrix); (5) 15%D: 15-percent

dispersed retention (uniform distribution of residual trees);

and (6) 15%A: 15-percent aggregated retention (two circular 1-ha forest aggregates in a cut matrix). Residual trees in

the dispersed treatments were selected from larger and more

stable dominants and co-dominants.

Before and after treatment in each unit, DEMO researchers

sampled overstory and understory vegetation, sporocarps

(mushrooms and truffles) of ectomycorrhizal fungi, canopy

arthropods, amphibians, forest-floor small mammals, and

diurnal breeding birds (Aubry et al. 1999). For most taxa,

sampling was conducted within a grid of 63 or 64 sampling

points with 40-m spacing. Herbaceous and woody plants

were measured on permanent fixed-area plots (Halpern et al.

1999, 2005). Mushrooms and truffles were tallied by genus

or species on temporary and permanent fixed-area plots

(Cazares et al. 1999, Luoma et al. 2004). Canopy arthropods

were sampled by collecting one branch in each third of the

canopy of one Douglas-fir tree. In 15- and 40-percent

aggregated-retention treatments, the sample tree was located

near the middle of a forest aggregate (Progar et al. 1999);

after harvest, an additional tree was sampled at the edge of

the aggregate (Schowalter et al., in press). Resulting samples were sorted to the lowest taxonomic level possible.

Amphibians and small mammals were sampled with pitfall

traps located at each grid point (Lehmkuhl et al. 1999). Traps

were opened for approximately 4 weeks during October

and early November between the onset of fall rains and the

beginning of snow accumulation. Diurnal breeding birds

were sampled by tallying all species detected within 50 m

of four point-count stations in each treatment unit, with stations ≥160 m apart and ≥80 m from the stand perimeter.

Point-counts were completed within 3 hours of dawn, and

repeated six times during the spring breeding period

(Lehmkuhl et al. 1999). 

Basal area, tree density, canopy depth, and canopy cover

were computed from the plot data before and after harvest,

along with various sets of indices of vertical diversity in

crown area profile (Dubrasich et al. 1997). Individual crown

profiles and implied canopy cover were estimated from

existing crown-width and crown-profile equations applied

to individual trees (Dubrasich et al. 1997, Hann 1998). The

first set of indices was based on the crown profile, irrespective of species. Vertical uniformity in this profile was

expressed in three ways: the standard deviation of crown

area among 0.5-m height intervals (SDCA); Shannon index

of diversity among 0.5-m height intervals (H’CA), with

crown area as the measure of abundance; and Pileou index

of evenness among the same 0.5-m height intervals (J’CA).
Because canopy diversity may result either from stratification of species into separate layers or from presence of

most species in all layers, a second set of indices was computed for the crown area profile of each species separately.

Weighted average indices (SDsp, H’sp, and J’sp) were then

determined by applying the total crown volume of each

species as the weight. The third set of indices was based 

on species diversity (H’), species evenness (J’), and species

richness (S) at each 0.5-m height interval in the stand. The

weighted mean of each measure was then computed across

height intervals by using total crown area at a given height

as the weight (H’ht, J’ht, Sht). 

To reduce the potentially confounding influences of

sampling error and variation in detection probabilities among

treatments and among taxa, we eliminated wildlife species

from consideration that were not effectively sampled with

the methods used, had spatial requirements that exceeded

the size of the treatment units, or were not associated with

forested habitats. We eliminated amphibians altogether

because only a few species were appropriate to include in

our analyses. For most taxa, only individuals that could be

identified to the species level were included. However, due

to the challenges involved in identifying many arthropods

and fungi to species, we also included higher level taxonomic designations for those groups. The primary response

variable for assessing potential losses in biological diversity

was the probability of detection failure; i.e., that a taxon

present before harvest was not detected after harvest. We

analyzed data for each taxonomic group as a whole, and

also conducted separate analyses on the subset of herbs,

small mammals, and birds that we considered to be closely

associated with late-seral forest conditions. 

The response variable in all analyses was binary with

respect to detection after harvest, with individual taxa

serving as observational units. We therefore performed

analyses of covariance (ANCOVA) in the context of generalized linear models, specifying a binomial regression with

logit link function (McCullagh and Nelder 1989). The preharvest measure of abundance for each taxon was introduced as a covariate to help account for differing probabilities

of detection between common and rare taxa. Overall treatment effects were tested by reduction-in-deviance tests

between a reduced model with only block effects and the

covariate vs. a full model with an added set of treatment

indicator variables. A set of a priori orthogonal contrasts

was also computed to test for differences among specific

treatments (table 2; Zar 1984). The ANCOVA was then

reformulated by retaining block effects but replacing categorical treatments with continuous variables representing

residual stand structure, initial stand structure, and change

in stand structure. If a significant set of stand structural

variables was found for a taxonomic group, we reintroduced

a set of indicator variables representing the treatments to

test for residual treatment effects. The effects of stand structural variables indicated by the binomial regressions were

assessed by first plotting the predicted probability of detection failure on stand-density reduction, while holding other

predictor variables constant. The probabilities were then

predicted across the same range in stand density reduction

for one to three additional levels of a second predictor to

produce several lines on the same graph. 

273

Table 1—General topographic and forest attributes for each of the six experimental 

blocks in the DEMO study. Minimum and maximum values represent treatment unit 

means.

Location/ Elevation Slope Stand Site index

Block (m) (%) Aspect age (yr) (m at 50 yr)

Oregon Cascade Range: Umpqua National Forest

Watson Falls 945-1310 4-7 flat 110-130 40-43

Dog Prairie 1460-1710 34-62 SW 165 30

Washington Cascade Range: Gifford Pinchot National Forest

Butte 975-1280 40-53 E-SE 70-80 27-32

Little White Salmon 825-975 40-60 NW-NE 140-170 30

Paradise Hills 850-1035 9-33 variable 110-140 26-33

Washington Coast Range: Washington State Department of Natural Resources

Capitol Forest 210-275 28-52 variable 65 37-41
274

RESULTS

The harvest treatments produced residual basal areas

ranging from 8.4 to 99.5 m2 ha-1; however, residual basal

area for a given treatment varied two-fold among blocks

due to differences in initial basal area (fig. 1). Canopy cover

was closely correlated with basal area, ranging from approximately 15 to 96 percent. However, cover was greater for a

given level of retention in the dispersed treatments due to

the uniform spacing of residual trees and lack of crown

overlap.

Analysis of covariance indicated significant treatment

effects for mushrooms, truffles, and birds (P ≤ 0.026; table

3). When bird and herb species with an affinity for lateseral forest conditions were analyzed separately, there was

a significant treatment effect for both groups (P ≥ 0.01;

table 4). Orthogonal contrasts showed that significant treatment effects for mushrooms, truffles, and late-seral herbs

were driven by greater detection failure in harvested units

relative to controls (tables 3 and 4). For all birds, a greater

proportion of species was “lost” from the 15-percent treatments than from the 40-percent treatments (P = 0.002), and

a greater proportion was “lost” from the dispersed treatments than from the aggregated treatments (P = 0.030).

Pretreatment abundance was a very significant covariate in

all ANCOVAs (P < 0.001).

Residual basal area was not a significant covariate in

any of the ANCOVAs (P > 0.05), although correcting for

differences in residual basal area by adding this covariate

strengthened the significance of many of the orthogonal

contrasts (data not shown).

The probability of “losing” an herb species increased

with both harvest intensity (greater reduction in tree density)

and residual basal area of Douglas-fir (fig. 2). As with the

other taxonomic groups, the probability of detection failure

for an herb species increased significantly as its preharvest

abundance declined (fig. 3). Stand-density reduction had a

similar effect on mushrooms and truffles, but for this group

the aspect of stand density that best captured the effect was

change in canopy cover. Canopy arthropods were most

responsive to descriptors of the crown area profile. Detection

failure rates increased with greater reduction in speciesspecific canopy diversity (decline in H’sp). The strongest

predictor for canopy arthropods, however, was height-specific canopy species richness (Sht); treatments imposing a

greater decline in average tree species richness for a fixed

canopy height resulted in an increase in the probability of

detection failure. Similar to herbs, birds responded most

strongly to reductions in stand density, particularly as measured by change in total basal area. For birds, however, detection failure rate was significantly higher in dispersed than

in aggregated treatments (fig. 4). Residual canopies that were

characterized by greater diversity (lower SDCA) had a

higher probability of bird species “loss.” 

When categorical treatment variables were tested in

models containing stand structural attributes, no marginal

treatment effects could be detected. One or two stand structural variables performed about as well as categorical treatment variables alone.

DISCUSSION

Correct interpretation of the “effects” of canopy structural variables requires an understanding of how variableretention treatments change crown area profiles. For example,

the dispersed-retention treatments tended to produce profiles with a more uniform vertical distribution of crown area,

so although crown volume was substantially reduced, SDCA

indicated greater vertical diversity. If the treatment units

were relatively uniform in structure, aggregated-retention

Table 2—Orthogonal contrasts in the DEMO study for treatment effects analyzed with ANCOVA

Name Treatment contrast

Treatment 100% vs. 75%A, 40%D, 40%A, 15%D, 15%A

Level 40%D, 40%A vs. 15%D, 15%A

Pattern 40%D, 15%D vs. 40%A, 15%A

Interaction 40%D, 15%A vs. 40%A, 15%D

75% 75%A vs. 40%D, 40%A, 15%D, 15%A
275

Table 3—Test of treatment effects on the probability that a taxon present before harvest was not detected after

harvest. P-values are shown for the null hypothesis of no treatment effect. Only significant (P < 0.05) and marginal

(0.05 < P ≤ 0.15) test results are shown. 

Forest-floor Diurnal

Canopy small breeding

Test Herbs Shrubs Mushrooms Truffles arthropods mammals birds

Treatment effect — — 0.002 0.026 — — 0.006

Orthogonal contrasts

Treatment — — 0.001 0.005 — — — 

Level — 0.069 0.017 0.109 — — 0.002

Pattern — — — — — — 0.030

Interaction — — — — — — — 

75 percent — — 0.011 0.067 — — — 

Table 4—Test of treatment effects on the probability that a taxon associated with late-seral forest conditions that

was present before harvest was not detected after harvest. P-values are shown for the null hypothesis of no treatment effect. Only significant (P < 0.05) and marginal (0.05 < P ≤ 0.15) test results are shown. 

Late-seral, forest-floor Late-seral diurnal 

Test Late-seral herbs Late-seral shrubs small mammals breeding birds

Treatment effect 0.005 — — 0.010

Orthogonal contrasts

Treatment 0.002 — — — 

Level — — — 0.038

Pattern 0.110 — — — 

Interaction — — — — 

75 percent 0.028 — — — 

Figure 1—Residual basal area for each treatment unit in each block of the DEMO study. D = dispersed; A = aggregate.
276

treatments should have had little effect on the diversity of

the average crown-area profile. However, these treatments

obviously increased horizontal variation in stand density

and other aspects of stand structure. Also, because dominant and codominant trees were retained in the dispersed

treatments, structure was homogenized. The strong correlation between variables representing stand density and those

representing vertical canopy structure made assessing their

relative importance difficult, however. For example, the probability of detection failure for birds increased with residual

canopy diversity, a result attributable to a combination of

greater tree density and more even distribution of crown

volume among canopy layers. As stand density is reduced,

intensity of disturbance and impacts to the structure of forest-floor habitat, food sources, and microclimate increase.

Greater residual canopy diversity may either indicate lower

effective canopy cover (because canopy diversity increases

with decreasing retention) or perhaps a reduced probability

of detecting a species that is present (Gu and Swihart 2004).

The short-term function of residual live trees as refugia

for different forest species was substantiated in a general

way by early results of the DEMO variable-retention

experiment. As noted earlier, apparent “loss” of taxa can be

attributed to several alternative explanations besides local

extirpation. For plants and fungi these include sampling

error, burial by slash, destruction of only above-ground plant

parts by harvesting, reduced sporocarp production, and temporary dormancy induced by microclimatic stress (e.g.,

Lessica and Steele 1994). For small mammals and birds,

failure to detect a species after harvest may have been due

to a real change in abundance induced by the harvest treatments, but also to sampling error or a change in probability

of detection (Gu and Swihart 2004, Hopkins and Kennedy

2004). For example, if the treatments affected home range

sizes or travel patterns of small mammals or the behaviors

of birds, treatment effects could be partly attributable to

changes in detection probabilities. 

For each taxonomic group, the proportion of taxa that

were not detected after timber harvest depended directly or

indirectly on the degree of disturbance represented by each

harvest treatment. In some cases (mushrooms, truffles, and

birds), this effect was evident in the orthogonal contrasts

Figure 2—Trend in probability that an herb species present before harvest was not detected after harvest, as a function of reduction in stand density and residual Douglas-fir basal area. Preharvest frequency was also a predictor in

the binomial regression and was held constant at 30 microplots per treatment unit. 
embedded in each ANCOVA. However, continuous structural variables introduced in the regression analyses revealed

direct or indirect effects of variable-retention harvesting

that could not be detected with ANCOVA. To some degree,

a single covariate representing residual stand density was

redundant with the categorical treatment variables, as indicated by the lack of significance for residual basal area in

the ANCOVAs. Sets of continuous covariates, however,

depicted more detailed aspects of stand or habitat structure

(i.e., structural variability within the same nominal treatment), to the extent that categorical treatment variables

could add no further explanatory power to the regression

models. 

For at least one taxonomic group (birds), the more widespread disturbance in dispersed treatments resulted in greater

species “loss” than in aggregated treatments at corresponding levels of retention. Although a continuous variable

representing variation in horizontal stand structure may have

been capable of accounting for this effect, categorical representation in the ANCOVA was adequate for DEMO given

the standardized shape and size of forest aggregates.

Subtle variation in residual stand structure at a given level

of retention may have important implications that vary with

the habitat requirements of individual species. Taxa that are

restricted to the forest floor, such as herbs and ectomycorrhizal sporocarps, were influenced primarily by changes in

stand density. Conversely, taxa utilizing more of the vegetation profile, such as canopy arthropods and birds, responded

to both changes in stand density and more subtle variation

in crown-area profile. Small mammals responded in a manner that was intermediate between these groups. Factors such

as risk of wind damage constrained the potential range in

residual tree size and stand structure that could be achieved

with variable-retention treatments, but some variation in

design could have had a significant effect on residual species

diversity, at least for a limited time after harvest. For example, leaving a wider range of tree sizes in dispersed-retention treatments would have enhanced vertical diversity, but

this objective may not be achievable if trees from lower

crown classes in the original stand are more susceptible to

windthrow. However, variable-retention treatments that

promote variation in the size and species of retained trees

seem capable of retaining a greater variety of wildlife

species immediately after harvest. Such modifications of

277

Figure 3—Trend in probability that an herb species present before harvest is not detected after harvest, as a

function of reduction in stand density and preharvest microplot frequency. Residual Douglas-fir basal area

was also a predictor in the binomial regression and was held constant at 30 m2/ha.
the variable-retention treatments implemented in this study

may promote greater structural diversity and, hence, greater

retention of late-seral species in future stands.

Further analyses will focus on hypothesized interactions

and trophic relationships among various taxa, applying such

approaches as path analysis and structural equation modeling. However, further inferences are limited by the relatively

low degrees of freedom resulting from the small number of

treatment units in the DEMO study. This statistical issue is

one that typifies many other forest ecological experiments

conducted on an operational scale. On-going field work to

monitor responses of various taxa will facilitate interpretation of short-term responses in the context of longer term

changes in presence and abundance, and should clarify some

of the mechanisms by which populations are responding to

the variable-retention treatments.

ACKNOWLEDGMENTS

This research is a component of the Demonstration of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of

Washington.

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Figure 4—Trend in probability that a bird species present before harvest was not detected after harvest, as a function

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1 Wildlife Sciences, College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195, USA. Email for corresponding author:

calypte@u.washington.edu

2 Cascadian, Inc., 1903 NW Lantana Drive, Corvallis, OR 97330, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Effects of Forest Structural Retention Harvest on Resource 

Availability and Habitat Utilization of Bark-Foraging Birds

Maria Mayrhofer,1 David Manuwal,1 and Juraj Halaj2

INTRODUCTION

Forest harvest with structural retention is gaining importance as a forest management tool in the Pacific Northwest.

An important element of this silvicultural treatment is the

preservation of late-successional forest characteristics to

conserve biodiversity. Effective implementation requires a

thorough understanding of how changes in forest structure

affect ecological processes and community development. The

Demonstration of Ecosystem Management Options (DEMO)

study is an attempt to provide empirical evidence to evaluate the effects of green-tree retention in the Douglas-fir

(Pseudotsuga menziesii (Mirb.) Franco) dominated forests

of the western United States. From the standpoint of ecological research, the DEMO study design provides a unique

opportunity to study species and habitat interactions at

scales relevant to forest management.

Previous studies on experimental silvicultural techniques

in Oregon and Canada have reported positive effects on

bird community composition and abundance with increasing retention of forest legacy components. However, recent

literature reviews of several studies on forest fragmentation

and thinning point out that most studies recorded changes

in bird abundance but failed to investigate underlying ecological mechanisms. Understanding the biological processes

that determine avian viability would provide insight on the

effects of various silvicultural treatments and help make

inferences on forest management strategies. 

The negative effects of timber harvest on the abundance

of cavity-nesting birds such as the brown creeper (Certhia

americana), red-breasted nuthatch (Sitta canadensis), and

hairy woodpecker (Picoides villosus) has been demonstrated

281

by previous studies. The post-harvest assessment of the

DEMO bird community study reported a significant decline

in the brown creeper, a bark-foraging species, and a decreasing trend in the red-breasted nuthatch in the 40-percent and

15-percent aggregated and dispersed retention treatments.

The brown creeper prefers old-growth forest conditions with

a continuous canopy cover and high stand density. It is categorized as a forest-interior species that is sensitive to edges

and forest thinning activities. Thus the brown creeper is a

good indicator species for the effects of the various levels

and patterns of forest harvest in the DEMO units. However,

the ecological mechanisms that underlie the brown creeper’s habitat needs have not been well studied. 

The habitat factors that influence bird abundance include

suitable nest sites, presence of predators, food abundance,

and the quality of foraging sites. The tree retention treatments of the DEMO units affect these factors to different

degrees. The availability of adequate nest sites in the form

of snags is a limiting factor to the abundance of cavity

nesting birds such as hairy woodpeckers and red-breasted

nuthatches. Preferred nesting snags and trees usually have

large diameters (>50cm d.b.h.) and advanced decay or heart

rot. In addition, brown creepers often prefer sloughing bark

so they can create their nest-cavity under the bark slab. Forest

management typically reduces tree density, removes snags,

creates more edge, and fragments habitat. Nest sites close

to edges, in particular, can be subject to increased predation.

Bird nests in forests are under predation pressure from a

large and diverse community of predators. The abundance

and community composition of nest predators depends on

the type and quality of the habitat and the influence of the

surrounding landscape. 
282

Arthropods are the main food source for bark-foraging

bird species. Changes in forest structure following harvest

result in alterations of microclimatic regimes and, consequently, the quality of arthropod habitat. These changes can

cause differences in arthropod abundance and guild composition and thus food availability for bark-foraging birds

among DEMO retention treatments. Specific habitat

resources can differ in importance to the birds, and can constitute an ultimate threshold that determines the presence or

absence of a bird species. Analyzing the variety of resources

that a bird uses in its home range can provide insights into

the importance of specific habitat attributes. The main objective of this study was to determine if the various degrees

and patterns of timber harvests intended to retain certain

aspects of forest structure affected the resource availability

and habitat utilization of the bark-foraging birds brown

creeper, red-breasted nuthatch and hairy woodpecker. 

STUDY DESIGN

The design of this study is based on the methods of

Marzluff et al. (2004). A resource utilization distribution

(UD) can assess the relative importance of specific habitat

resources for a bird such as the brown creeper and demonstrate its sensitivity to other habitat characteristics. A UD

of the DEMO units will provide insights on the usefulness

of varying levels and spatial distributions of retained green

trees and snags for brown creepers. The UD can be expressed

as a probabilistic density function of bird resource use.

Kernel density estimation is the optimal technique to define

resource UD with adequate spatial point sampling. Each

mapped brown creeper territory was defined as a 100-percent fixed Kernel home range boundary that estimates a

100-percent probability that the bird will be located in this

territory. During the 2003 breeding season, we collected 30

to 230 relocation points per brown creeper territory, which

is an adequate sample size for Kernel home range estimates.

Using the fixed Kernel estimates with least squares cross

validation, we generated the UD with the ArcView extension “Animal Movements.” The ArcView extension “Focal

Patch” calculates the density of a bird’s UD at each sampling point, which estimates the intensity of the bird’s habitat

use. Using ArcView, we can spatially reference the following resource attributes of the DEMO units: percent forest

cover, percent edge/patch size at aggregated retention treatments, food abundance in form of arthropod abundance and

guild composition, and nest predator abundance and community composition. The ArcView extension “Focal Patch”

intersects with “Patch Analyst” and measures resource attributes at each grid cell and associates them with the density

of the brown creeper UD at every sampling point. 

The relationship between DEMO resource attributes and

the brown creeper UD can be further analyzed by using

multiple linear regression techniques. The statistical software package, R, uses the ArcView data to generate a

resource utilization function (RUF). The coefficients of the

RUF regression provide a measure of the intensity of DEMO

resource use by the brown creeper. The Kernel point estimates introduce spatial autocorrelation into the data, but are

accounted for by the error term in the regression model. The

coefficients of habitat attributes, such as forest cover or

food abundance, can be tested against each other for their

significance in the bird’s resource use. To compare the probabilities of resource use of all sampled brown creepers for

possible population inferences, the individual birds (RUFs)

need to be considered as independent samples with similar

choice selection among DEMO forest resources. Coefficients

that are not available in a bird’s territory range can be set

equal to zero. It is possible to pool only individual birds

that have the same coefficients of habitat resources available

in their territory. Using the pooled bird data, we can calculate an average RUF to make inferences on the use of various

DEMO forest resources at a population level. This information could be used in forest management decisions. 

METHODS

During the breeding season of 2003 (May through midAugust), we attempted to capture all brown creepers that

established a territory at the 5 treatment units of the two

Oregon DEMO blocks, Watson Falls and Dog Prairie. The

5 experimental harvest retention treatments consisted of a

100-percent control unit, 40-percent and 15-percent dispersed, and 40-percent and 15-percent aggregated forest

units. The Douglas-fir dominated forests were all beyond

the stem exclusion phase, but among the different treatment

units, the stands included a variety of disturbance histories

and ages. Male brown creepers were caught with mist-nets

by attracting them with territorial call-backs and bird decoys.

The birds were banded with U.S. Fish and Wildlife aluminum leg bands and with two additional colored leg bands.

To improve individual bird identification in the field, the

creepers’ two central retrices were also color-marked with

duct tape the same color as the birds’ leg band combination.

Throughout the breeding season, all brown creepers were

spot-mapped by using the existing grid system to determine

the location and size of the birds’ territories at the DEMO

treatment units. In addition to spot-maps, we used global

positioning system (GPS) units to map habitat use of brown

creepers whose territories extended into the adjacent forest

beyond the DEMO experimental units. This method ensured

that the entire brown creeper territory was mapped and thus

all habitat use investigated. 
Due to logistic constraints, we were only able to spotmap hairy woodpecker and red-breasted nuthatch activities

on the DEMO treatment sites and the adjacent forest. Territory use in the forest beyond the edge of the experimental

units was not mapped, and the woodpeckers and nuthatches

were not color banded. We conducted nest searches for all

3 target species, and the nesting progress was checked every

4 to 7 days. To determine the breeding status and reproductive success, we recorded the Vickery Index for every 

territory. Nest site characteristics were assessed by using

circular vegetation plots (0.05 ha radius) around each nest

tree. Encounters with the following potential nest predators

were spot-mapped at all DEMO sites: Douglas squirrels (Tamiascurus douglasii), chipmunks (Tamias sp.), house

wrens (Troglodytes aedon) and corvids (Cyanocitta stelleri,

Corvus corax, Perisoreus canadensis). Food availability in

the form of bark arthropods was sampled by crawl traps

installed on the trunks of 20 live trees and 20 snags in every

treatment unit. To accurately determine food abundance,

we refined our arthropod samples to match the diet preferences of our focal bird species using fecal sample analysis

obtained from the captured and banded brown creepers and

a priori knowledge. 

RESULTS

At the time of this abstract submission, the second field

season of this study is in progress. Preliminary results on

brown creeper utilization distribution will be presented

during this workshop. 

ACKNOWLEDGMENTS

This research is a component of the Demonstra-tion of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of Washington. 

REFERENCES

Marzluff, J.M., et al. 2004. Relating resources to a probabilistic measure of space use: forest fragments and

Steller’s jays. Ecology. 85(5): 1411-1427.

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1 Research Ecologist and 2 Forester, USDA Forest Service, North Central Research Station, Grand Rapids, MN 55744, USA. Email for corresponding

author: bpalik@fs.fed.us 

3 Research Scientist, and 4 Research Associate, Jones Ecological Research Center, Newton GA 39870, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Using Spatially Variable Overstory Retention to Restore 

Structural and Compositional Complexity in Pine Ecosystems

Brian J. Palik,1 Christel C. Kern,2 Robert Mitchell,3 and Stephen Pecot4

INTRODUCTION

There is a fundamental truth that is apparent when contrasting forests that develop naturally (i.e., in response to

natural disturbances and development processes) to those

that develop in response to management: nature generates

complex forest stands, whereas management (for wood 

production) simplifies them. The complexity inherent in

natural stands is embodied in diverse (in a relative sense)

age and size structures, diverse tree composition (again, in

a relative sense), abundant large coarse woody debris,

diverse understory, shrub, and ground layer plant communities, and spatially variable (horizontal and vertical) patterns in these attributes. 

ABSTRACT

Increasingly, forest managers incorporate overstory retention into silvicultural prescriptions for forests traditionally managed for single-cohort structure. The ecological benefits of retention may come at the cost of reduced growth of tree regeneration because of competition with residual trees. An important question in retention research, and its application, is how

spatial pattern of retention (e.g., dispersed, aggregate) influences resource availability and heterogeneity, competitive environments, and regeneration dynamics. Recently, we initiated two operational-scale experiments in pine ecosystems (longleaf

pine (Pinus palustris Miller) in southern Georgia, USA and red pine (Pinus resinosa Aiton) in northern Minnesota, USA) to

address questions about the influence of retention pattern on resource availability and tree regeneration. These experiments

address the hypothesis that resource availability at the stand scale will be highest with aggregate retention rather than dispersed retention because of nonlinear relationships between competitor abundance and target plant response. In both studies,

our goal is to test approaches for restoring age diversity in single-cohort stands, while minimizing competitive inhibition of

the new cohort. Our initial results show clearly that spatial pattern of retention has a significant effect on stand-scale resource

availability and regeneration growth.

KEYWORDS: Structural complexity, biological legacies, overstory retention, longleaf pine, red pine, regeneration, plant

competition, productivity. 

285

Complexity in natural stands is characteristic of all

forests, including those that initiate following stand-replacement disturbances. Such forests rarely display the simplified

structure that is characteristic of clearcuts, but rather include

a rich legacy of biological (or biologically derived) structures that survive the disturbance and provide critical habitat, sustain important functions, and influence recovery

processes in the post-disturbance ecosystem. 

Incorporating biological legacies into regeneration 

harvest prescriptions has emerged as an important principle

of ecological forestry and is being implemented in many

regions (Franklin et al. 1997, Lindenmayer and Franklin

2002, Palik and Zasada 2002, Vanha-Majamaa and Jalonen
2001). More specifically, retention of live, large overstory

trees during regeneration harvest is one of the more obvious ways that foresters incorporate the legacy concept into

management, particularly in forests that traditionally are

managed for single-cohort structure.

Retention prescriptions for large trees (indeed, for all

types of legacies) must address three questions: what species

and sizes to retain, how many trees to retain, and what spatial pattern of retention to use—e.g., dispersed or spatially

aggregated. It is the third question regarding spatial pattern

of retention and influence on ecosystem responses that we

are exploring. Spatial pattern of retention is receiving scrutiny

(Franklin et al. 1997) because some ecological objectives

may be sustained by dispersing retained trees whereas other

objectives may be sustained by aggregating retained trees.

Additionally, spatial pattern of retention may lead to profound differences in growth and productivity of trees (Palik

et al. 1997, 2003). Our premise is that the ecological benefits of retention may come at the cost of reduced growth

rates of tree regeneration because of competition with

residual overstory trees. On the other hand, retention may

provide a tool to better control the diversity of resource

environments and the mixture of species regenerating in

the stand. 

Recently, we initiated two operational-scale experiments

in pine ecosystems (longleaf pine (Pinus palustris Miller)

and red pine (Pinus resinosa Aiton)) to address the influence of retention pattern on resource availability and tree

regeneration. Similar experimental approaches were used

in both study forests. In both studies, our goal was to test

approaches for introducing structural complexity into simplified stands, while minimizing competitive inhibition of

the new cohort of pines. 

STUDY AREAS

The longleaf pine experiment was conducted in southern Georgia, USA, on the property of the Jones Ecological

Research Center. The red pine study is being conducted in

northern Minnesota, USA, on the Chippewa National Forest.

Both study systems occur on deep, loamy sand soils. Historical age structures for the two systems are characterized

by two to many cohorts of the dominant pine species. Longleaf pine forests are almost exclusively mono-dominant,

whereas red pine forests historically contained admixtures

of jack pine (Pinus banksiana Lamb.), eastern white pine

(Pinus strobus L.), and several hardwood species.

EXPERIMENTS

The general experimental design is similar for both pine

systems (fig. 1). Four retention treatments are assigned randomly within replicate blocks and include uncut control,

dispersed retention, small-gap cutting, and large-gap cutting (the latter two treatments result in aggregate residual

tree retention). The retention treatments are cut in similar

residual basal areas (12 m2/hectare (ha) for longleaf pine

and 18 m2/ha for red pine). Stand sizes are 2 to 3 ha for

longleaf pine and 15 to 25 ha for red pine. The different

residual basal areas in the two studies reflect natural differences in stocking for the two forest types; i.e., longleaf

pine stands typically have low basal area, relative to red

pine stands. Moreover, the differences in stand sizes correspond to the average patch sizes of management units on

the two properties. Gap sizes are approximately 0.1 (small)

and 0.3 (large) ha. Approximately 5 small and 2 large gaps

were cut in each treatment stand for the longleaf pine study,

while in the red pine experiment, gap numbers averaged

around 28 (small) and 18 (large), respectively in each unit.

Additionally, for the red pine experiment, the residual

matrix between gaps was lightly thinned. 

After harvest, nursery-grown seedlings were planted

across the range of residual overstory basal areas in each

treatment stand. For the longleaf pine experiment, only

longleaf pine seedlings were planted, since these systems

are typically mono-dominant. For the red pine experiment,

equal mixtures of red pine, eastern white pine and jack

pine were planted because all three pines can occur in these

systems.

We are also examining the competitive interaction of

understory vegetation and a new tree cohort. In both experiments, half of planted seedlings receive understory competition control (herbicides in longleaf pine; manual cutting

in red pine), whereas the other half receive no understory

control. We were unable to use herbicides to control the

understory on the national forest study area. Here we report

only on results from the understory control treatment.

Response variables measured include survival and

growth (ground level diameter, biomass) of the planted

pine seedlings and light (as a percentage of photosynthetically active radiation (PAR) in the open measured by using

a LICOR LAI 2000 sensor), nitrogen (using resin exchange

beads), and water availability (using time domain reflectometry (TDR)). Additional variables being measured in

the red pine experiment include natural regeneration establishment and growth, biomass productivity of the residual

286
cohort, shrub and herbaceous layer productivity, plant richness and community composition, tree pathogen responses,

coarse woody debris dynamics, and songbird communities.

HYPOTHESES AND CONCEPTUAL

BACKGROUND

Our experiments address the hypothesis that the availability of resources at the stand scale and heterogeneity will

be higher with aggregate retention than dispersed retention

because of a nonlinear (negative exponential) relationship

between competitor abundance and target plant response

(Palik et al. 1997). Research on plant competition has demonstrated the shape of this plant interaction relationship (fig. 2),

in which target plant growth is low across a wide range of

competitor abundance and only increases (exponentially)

below threshold levels of low competitor abundance. It is

hypothesized that the growth relationship reflects the pattern of availability of two or more limiting resources; e.g.,

it is only at low competitor abundance that light and nitrogen are both abundant (Palik et al. 2003).

We have used this neighborhood-scale relationship 

(i.e., the area immediately around the target plant) to generate stand-scale hypotheses about resource availability and

growth of regeneration under different spatial patterns of

retention (Palik et al. 1997, 2003). Specifically, given a fixed

(and low) level of residual basal area in harvest stands, we

predict that resource availability to a new cohort of trees

will increase slowly from an uncut (control) stand, through

dispersed retention, to small-gap aggregate retention, and

will only increase exponentially where aggregate retention

provides for many large openings in the stand (fig. 1).

Similarly, we predict that new cohort (target plant) growth

will follow a similar pattern, increasing exponentially only

with aggregate retention that incorporates many large openings in the stand. The theoretical basis for these stand-level

hypotheses is this: only when retention is aggregated, and

large openings exist, will sufficient competitive neighborhoods be far enough away from overstory competitors to

be free of extreme resource competition, i.e., they fall far

to the left on the interaction curve (fig. 2). 

RESULTS AND SUMMARY

Our research in the longleaf pine system is complete,

and we have reported on this work elsewhere (Battaglia et

al. 2002, 2003; Jones et al. 2003; Palik et al. 2003). In contrast, our experiment in red pine is ongoing; harvest treatments were installed in winter 2002-2003, and seedlings

were planted in spring 2003. In the following sections, we

summarize major findings of the completed longleaf pine

experiment and highlight some of the features of the red

pine experiment currently in progress.

Longleaf Pine Ecosystems

At the neighborhood-scale, resource availability and

seedling growth of longleaf pine varied across the range of

overstory abundance, expressed as overstory abundance

index (a distance weighted measure of total basal area with

15 m of the seedling), according to the hypothesized negative exponential relationship (fig. 2). Nitrogen availability

287

Figure 1—Conceptual representation of overstory retention treatments that

differ in spatial pattern of residual trees. (A) undisturbed forest, (B) dispersed retention, (C) small gap thinning, (D) large gap thinning. Treatments

B to D have the same residual overstory basal area. Note: in the red pine

experiment only, some thinning also occurred in the residual matrix

between the gaps. 

Figure 2—Conceptual relationship between competitor abundance and target plant growth.
(fig. 3) increased only marginally across a wide range of

overstory abundance, but increased more rapidly at low

overstory abundance. Gap light index responded similarly,

although the increase in light began at a higher overstory

competitor abundance than with nitrogen (fig. 4). Aboveground seedling biomass growth responded similarly to

nitrogen. Biomass increment was low and nearly constant

across a wide range of overstory competitor abundance and

increased exponentially at low overstory abundance (fig. 5).

The response of below-ground biomass increment was similar to above-ground biomass increment (data not shown).

At the stand scale, resource availability and seedlings

growth responses were as hypothesized. Nitrogen availability was lowest in the control stands, increased with 

dispersed retention and small-gap retention, and was greatest with large-gap retention (fig. 6). Similarly, gap light

index increased across the same treatment array, although

with more muted differences among treatments (fig. 7).

Finally, the above-ground seedling biomass increment was

similar among control, dispersed retention, and small gap

thinning treatments, but increased substantially in the large

gap thinning treatment (fig. 8). Our major findings, based

on these results, are listed below:

288

Figure 3—The response of nitrogen availability (expressed as NH4+N03) 

to overstory abundance index (a distance weighted measure of total basal

area with 15 m of the sample point) in a longleaf pine woodland (from

Palik et al. 2003).

Figure 5—The response of above-ground longleaf pine seedling biomass

increment to overstory abundance index (a distance weighted measure of

total basal area with 15 m of the seedling) in a longleaf pine woodland

(from Palik et al. 2003). 

Figure 4—The response of gap light index (expressed as percentage of an

open condition) to overstory abundance index (a distance weighted measure of total basal area with 15 m of the sample point) in a longleaf pine

woodland (from Palik et al. 2003).

Figure 6—Soil nitrogen availability (expressed as NH4+N03 ) in four

retention treatments in a longleaf pine woodland. Values are means (±se)

of three replicates (from Palik et al. 2003).
• All treatments retained significant structural complexity

similar to mature overstory longleaf pine systems.

• Resource availability and competitive environments in

the understory differed dramatically, depending on spatial

arrangement of retained trees. 

• Retaining trees in aggregates, through large-gap cutting,

provided the most favorable resource environment for

regenerating longleaf pine seedlings (in the absence of

competing herbaceous and shrub competition). 

• We expect similar (although muted responses) in

resources and regeneration growth in the presence of

competing herbaceous and shrub vegetation.

Red Pine Ecosystems

As with the longleaf pine experiment, we are examining

resource availability in the red pine experiment and new

cohort growth. Additional objectives, not included in the

longleaf pine study, include an examination of 

• Regeneration survival and growth of pine species differing in shade tolerance 

• Development of natural regeneration

• Recruitment of large dead wood

• Productivity patterns and trade-offs between cohorts and 

among structural layers

• Responses of shrub and herbaceous plant communities 

to treatments

• Responses of red pine shoot pathogens to treatments

• Migratory songbird responses

We predict similar neighborhood and stand-scale

responses in resource availability and seedling growth to

retention treatments, and consequently, the same set of

major summary points are likely to be true for the red pine

system. Additionally, we have posed a set of stand-scale

hypotheses for some of the other response variables listed

below:

1) Residual cohort production. Among the three harvest

treatments, productivity of the residual cohort will

increase from large-gap retention to small-gap retention

to dispersed retention because of decreasing inter-tree

shading and greater ability to preempt soil resources.

2) Shrub-herb preemption. Among the three harvest treatments, resource capture and productivity of shrub and

herb layers will be maximized with large-gap retention

and minimized with dispersed retention because of

decreased ability of the residual tree cohort to capture

resources in the former treatment.

3) Residual tree blowdown. Among the three harvest treatments, blowdown of residual trees will be maximized

with dispersed retention and minimized with gap-retention because of decreased mutual protection and support

among neighboring trees with the former treatment.

4) Ground layer plant communities. Composition of

ground layer plant communities will be less altered with

aggregate (gap-based) retention relative to dispersed

289

Figure 7—Gap light index (expressed as percentage of an open condition) in four retention treatments in a longleaf pine woodland. Values are

means (±se) of three replicates (from Palik et al. 2003).

Figure 8—Above-ground longleaf pine seedling biomass increment in

four retention treatments in a longleaf pine woodland. Values are means

(±se) of three replicates (from Palik et al. 2003).
290

retention because a greater percentage of the stand will

be left in an unharvested (or minimally harvested) condition.

REFERENCES 

Battaglia, M.A; Mou, P.; Palik, B.; Mitchell, R.J. 2002. 

The effect of spatially variable overstory on the understory light environment of an open-canopied longleaf

pine forest. Canadian Journal of Forest Research. 

32: 1984-1991.

Battaglia, M.A.; Mitchell, R.J.; Mou, P.; Pecot; S.D. 2003. 

Light transmittance estimates in a longleaf pine woodland. Forest Science. 49: 752-762.

Franklin, J.F., Berg, D.; Thornburgh, D.A.; Tappeiner. J.C. 

1997. Alternative silvicultural approaches to timber harvesting: variable retention harvest systems. In: Kohm,

K.A.; Franklin, J.F., eds. Creating a forestry for the 21st

century. Washington, DC: Island Press: 111-140.

Jones, R.H.; Mitchell, R.J.; Stevens, G.N.; Pecot. S.D.

2003. Controls of fine root dynamics across a gradient

of gap sizes in a pine woodland. Oecologia. 134: 

132-143.

Lindenmayer, D.B.; Franklin, J.F. 2002. Conserving forest 

biodiversity. A comprehensive multi-scaled approach.

Washington, DC: Island Press. 351 p.

Palik, B.J.; Mitchell, R.J.; Houseal, G.; Pederson, N. 1997. 

Effects of canopy structure on resource availability and

seedling responses in a longleaf pine ecosystem.

Canadian Journal of Forest Research. 27: 1458-1464.

Palik, B.; Mitchell, R.J.; Pecot, S.; Battaglia, M.; Mou. P. 

2003. Spatial distribution of overstory retention influences resources and growth of longleaf pine seedlings.

Ecological Applications. 13: 674-686. 

Palik, B.; Zasada, J. 2003. An ecological context for regenerating multi-cohort, mixed-species red pine forests.

Res. Note. NC-382. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest

Experiment Station. 8 p.

Vanha-Majamaa, I.; Jalonen, J. 2001. Green tree retention 

in Fennoscandian forestry. Scandinavian Journal of

Forest Research Supplement. 3: 79-90.
291

1, Wildlife Conservation Society, 219 SW Stark Street, Suite 200, Portland, OR 97204, USA. Email for corresponding author: szack@wcs.org 2 Department Wildlife, Humboldt State University, Arcata, CA 95521, USA

3 Wildlife Conservation Society, 2814 E. Waverly Street, #2, Tucson, AZ 85716, USA

Balancing Ecosystem Values Proceedings, Biodiversity

Wildlife Response to Fire and Thinning 

Treatments in Ponderosa Pine

Steve Zack,1 Kerry Farris,2 and Luke George3

There is growing consensus that ponderosa pine (Pinus ponderosa P.&C. Lawson) forests need widespread management

with prescribed fire and thinning. The structure and natural processes of these forests have been dramatically altered in the

past 100-plus years primarily due to fire suppression and large-tree logging. The park-like appearance of these pine forests,

which were the result of frequent, low-intensity fires, have been replaced by dense stands of pines and encroaching fir (Abies

spp.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) throughout its range. Likewise, the avifauna of these pine

forests has been affected, with several species considered in decline (e.g., white-headed woodpecker (Picoides albolarvatus),

olive-sided flycatcher (Contopus cooperi), and white-breasted nuthatch (Sitta carolinensis)). We are collaboratively engaged

(with scientists from the USDA Forest Service, Pacific Southwest Research Station in northern California and as part of the

National Fire and Fire Surrogate research) in experimental forest research at several locations in California and Oregon to

assess the wildlife response to alternative forest treatments of thinning and prescribed fire in comparison to controls (continued fire suppression). 

In general, we are finding that a foraging guild of bark gleaners (woodpeckers, nuthatches, creepers, and chickadees)

tend to respond positively to thinning and prescribed fire, whereas a foraging guild of leaf gleaners (vireos, tanagers, and

warblers) tend to respond negatively to such treatments. Further, we are beginning to understand how Picoides woodpeckers

respond to fire treatments, and how interactions between fire, woodpeckers, bark beetles, and fungi can result in snag decay

that facilitates the possibility of cavity excavation. Snags with cavities are a critical wildlife resource. It seems clear that

working with, and not against, fire helps create structures and revitalizes processes important to wildlife.
David Marshall and Robert Curtis (retired), both from the Pacific Northwest Research Station, examine stand structure on research plots in Washington

State Capitol Forest. Photo by Tom Iraci
FIRE AND FIRE SURROGATES
Photo by Tom Iraci
1 University of Helsinki, P.O.Box 27, FIN-00014, Finland. Email for corresponding author: timo.kuuluvainen@helsinki.fi

2 The Finnish Forest Research Institute, P.O.Box 18, FIN-01301 Vantaa, Finland

Balancing Ecosystem Values Proceedings, Fire and Fire Surrogates

Restorative Management of Boreal Forest Stands 

With and Without Fire: An Experimental Approach

Timo Kuuluvainen,1 Saara Lilja,1 and Ilkka Vanha-Majamaa2

There is considerable interest in using fire, or imitating the effects of fire, to restore natural forest features and biodiversity to managed forest. We are carrying out experimental research in southern Finland to determine the effects of different

restorative cutting treatments, with and without fire treatment, on forest structure and regeneration, biodiversity, and timber

production. Our motivation is to test various approaches that will meet economic and biodiversity goals of forest management. The experiment is set up in mature, managed spruce-dominated stands on mesic sites; for sampling the stands are 

further divided in two parts, a moist and a dry biotope. The experimental treatments consist of shelterwood-type cutting 

(60 m3/ha standing retention trees) with four levels of down retention trees (5, 30, and 60 m3/ha) and a burning/no-burning

treatment. The treatments were replicated three times, resulting in 24 stands and 48 sample quadrates 20 x 40 m. 

The pretreatment inventories were done during the field season 2001. The cutting treatments were conducted in winter

2002 and the burnings in summer 2002. Post-treatment inventories of the described variables were carried out between 2002

and 2004. The follow-up variables include stand structure, tree mortality and regeneration, forest floor microhabitat diversity,

ground and field layer vegetation, humus and soil, epixylic lichens and bryophytes, invertebrates, coarse woody debris and

polypores, and soil microbes. The first post-treatment results of the experiment are presented. 

295
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1 Research Statistician, Redding Silviculture Laboratory, 3644 Avtech Parkway, Redding, CA 96002, USA. Email: mritchie@fs.fed.us

Balancing Ecosystem Values Proceedings, Fire and Fire Surrogates

Effects of Thinning and Prescribed Fire on Understory 

Vegetation in Interior Pine Forests of California

Martin W. Ritchie1

INTRODUCTION 

The distribution of stand structures found throughout the

range of ponderosa pine has been altered over the last 150

years. Past harvesting practices, fire exclusion, and grazing

have all played a role in the transition to a landscape often

dominated by young, dense stands and attendant increases

in fire-intolerant species (Agee 1994, Arno 2000). 

Changes in stand structure and species composition affect

resilience to disturbance events induced by insects or fire.

Dense stands have a greater risk of bark-beetle-induced

mortality (Oliver and Uzoh 1997) and reduced rates of individual tree growth (Cochran and Barrett 1995, Oliver and

Edminster 1988). Heavier concentrations of surface fuels and

ladder fuels make stands more susceptible to stand-replacing fires. 

ABSTRACT

An array of treatments were applied to ponderosa pine (Pinus ponderosa) stands in northeastern California in a large-scale

study designed to evaluate the effects of management on accelerating late-successional attributes. Treatments include both

mechanical manipulation (thinning) and prescribed fire. The three factors associated with late-successional stands considered in this study are the diameter distribution, species composition, and fire frequency. A potential treatment response is

the change in understory composition following treatment. Understory vegetation was sampled in the second growing season

after the burn treatment, and 3 to 5 growing seasons after mechanical treatments. A total of 79 distinct species were identified within the treatment units. Species richness appeared to be unaffected by treatments. The distribution of species within

treatment units was affected, but response was limited to only a few species. In general, understory species appeared to be

slightly more evenly distributed in treated units. Shrub species, primarily snowbrush (Ceanothus velutinus), were more

common in all treated areas, and white fir (Abies concolor) was less common, particularly in burned treatments. Bitterbrush

(Purshia tridentata) was not found through much of the study area, so conclusions for this key browse species are difficult

to make. There was no short-term effect of treatments on pine regeneration. The infrequency of pine regeneration, however,

suggests the need for long-term evaluation. 

KEYWORDS: Ponderosa pine, white fir, thinning, prescribed fire. 

297

Past treatment history has a significant effect on current

stand structure (Parsons and DeBenedetti 1979). Treatments

such as thinning from below and prescribed fire may affect

more than the growth and mortality of the dominant canopy.

Busse et al. (2000) have found that prescribed burning in

interior pine stands of central Oregon had no significant

effect on herbaceous vegetation cover, and that shrub cover

only declined slightly. Exclusion of fire is generally thought

to enhance conditions for survival of white fir (Burns and

Honkala 1990, Hopkins 1981). Thinning and prescribed

burning may create more favorable conditions for regeneration of ponderosa pine in these stands (Roy 1983). Reestablishment of fire may reduce levels of white fir survival

in the understory. By the same token, disturbance from fire

or thinning may increase levels of some common shrubs

found in the understory (Conard et al. 1985, Gratkowski

1962).
Studies are needed to evaluate these effects over time,

to obtain a better understanding of both short-term and

long-term effects (Halpern and Spies 1995). With changing

focus of management in the Pacific Northwest, we need a

better understanding of the effects of treatments on individual species and plant communities. The Northwest Forest

Plan (USDA and USDI 1994 a,b) established a network of

adaptive management areas throughout the Pacific

Northwest. 

The Goosenest Adaptive Management Area in northeastern California was designated for the evaluation of

treatments designed to accelerate development of latesuccessional features. The stands of this adaptive management area have been influenced by the past management

activities of the Long-Bell Lumber Company and the

Klamath National Forest.

During the 1930s, the Long-Bell Lumber Company

removed the largest, older ponderosa pine trees from much

of what is now the Goosenest Adaptive Management Area.

Subsequently, the Klamath National Forest obtained these

harvested areas, and over the last 50 years conducted varying degrees of sanitation and salvage harvesting. Stands

exhibiting late-successional characteristics are no longer 

a prominent feature of this area.

An interdisciplinary team of scientists from the Pacific

Southwest Research Station worked with managers from

the Klamath National Forest to implement an experiment

with prescriptions geared toward restoring late-successional

forest conditions (Ritchie, in press). The prescriptions

involve application of combinations of mechanical (thinning) treatments and prescribed fire. The experiment is a

large-scale effort, with 20 treatment units comprising over

1200 ha in the study. 

Thinning and prescribed fire will have direct effects on

stand structure as well as fuel levels. However, the composition of the understory vegetation may also be significantly affected as the canopy is opened (Peek and others 2001),

and this can be an important element of treatment response.

This study evaluates effects of these thinning and burning

treatments on understory vegetation abundance and species

richness.

METHODS

This study was installed in the Goosenest Adaptive Management Area (GAMA) in northeastern California (fig. 1)

at lat 41 ̊34’ N, long 121 ̊41’ W. The GAMA is located on

the Goosenest Ranger District of the Klamath National

Forest. Much of the region was harvested by Long-Bell

Lumber Company during the 1930s. The removal of most

valuable pine at that time, coupled with the exclusion of

fire resulted in a dense understory of white fir, a species

that appears to have previously been sparsely distributed

throughout the area.

Elevations in the treated areas range from 1480 to 

1780 m. Slopes are gentle, generally with a northwest aspect.

Soils in the study area are sandy loams or loams derived

from volcanic ash. Pumice overburden is common in the

area. Annual precipitation ranges from 13 to 51 cm and

averages 28 cm.

Measured in 1996, pretreatment stand quadratic mean

diameters ranged from 24.6 to 41.1 cm with a median of

29.0. Basal area ranged from 26.6 to 58.3 m2/ha, with a

heavy concentration of fir in smaller diameter classes. Red

fir (Abies magnifica) is present in the higher elevation stands,

but in this study we will make no effort to distinguish

between red and white fir in the overstory. The mean density for trees between 10 and 30 cm diameter was 250

stems/ha for true fir and 130 stems/ha for ponderosa pine.

The disparity between the two is even higher when considering stands with no recent sanitation/salvage work.

Experimental Design

Treatments were developed by an interdisciplinary

team, with a goal of accelerating the development of latesuccessional conditions. Three goals served as a focus for

the prescription: (1) accelerating the growth of the largest

trees in the stand while reducing density-related mortality,

(2) increasing the proportion of pine in these increasingly

fir-dominated systems, and (3) introducing low-intensity

fires through prescribed burning. 

Twenty experimental units were identified, each 40 ha

in size. Pretreament conditions varied within the experiment

(table 1), but there were no statistically significant differences between any of the recorded stand variables (p-values

> 0.65). The experiment features four treatments, with each

treatment replicated 5 times in a completely randomized

design. The four treatments are (1) a control, (2) a large-tree

emphasis thinning, (3) a pine emphasis thinning, and (4) a

pine emphasis thinning followed by prescribed fire. 

The treatment units were given a treated buffer strip

approximately 100 m in width, where possible. Roads

within the units were avoided, although in some instances

secondary roads do pass through treatment units. Treatments

298
299

Figure 1—Location of the Goosenest Adaptive Management Area.

were applied randomly to the units; the randomization

resulted in a higher concentration of large-tree units among

the lower elevations than the concentration of other treatments. 

The silvicultural prescription (Ritchie 2005) for pine

emphasis was designed to reduce stand density while retaining most ponderosa pine trees. The large-tree emphasis prescription was intended to reduce stand density by thinning

smaller diameter trees without regard for species. Both 

prescriptions were test-marked prior to implementation to

evaluate the effectiveness of the marking guidelines.

The pine-emphasis prescription was designed to increase

the proportion of pine, with a residual density target of 80-

percent basal area, by retaining existing pine and regenerating pine in planned openings. The prescription called for

thinning with a “D+5” rule (spacing in feet is equal to diameter in inches plus 5), with the constraint that all ponderosa

pine dominants and codominants greater than 30 cm were

retained regardless of spacing. Also retained were all sugar

pine (Pinus lambertiana) trees and snags greater than 38 cm.

In pine-emphasis treatments, approximately 15 percent

of the area was regenerated to pine by harvesting openings
and planting ponderosa pine seedlings. All trees in these

designated openings were removed with the exception of

the occasional sugar pine. Openings were generally located

in dense thickets of fir, or other areas with a very sparse

distribution of pine, and ranged in size from 0.15 to 1.35 ha.

Fire has been reintroduced to 5 of the 10 pine-emphasis

units subsequent to thinning. Although mortality was low,

the fire burned with light to moderate intensity through most

of the units (table 2). Application of prescribed fire is to be

maintained at a rate consistent with known fire history of

the study area, commensurate with the ability to carry surface fire through the stands. A study is underway to determine historical periodicity of fires in the GAMA. Fuel

levels are to be reevaluated periodically to determine the

optimum time to reburn.

The large-tree treatment was a thin from below (larger

diameter trees were retained), regardless of species, to a

residual spacing of 5.5 to 7.6 m. Because changing species

composition was not a specific goal of the large-tree treatment, no regeneration openings were created. The large-tree

emphasis treatment creates greater vertical and horizontal

uniformity than the pine emphasis treatment, but will likely

promote the development of stands with a greater proportion of true fir than observed in the pine emphasis treatment.

Although there was no specific guide to favoring pine in

this treatment, there was still some effect on species distribution since there is a higher proportion of fir in the smaller

diameter classes.

In all units, whole trees greater than 10 cm in diameter

were transported to the landing with low ground pressure

equipment minimize the buildup of surface fuels. Nonmerchantable material was chipped and processed off site. Cut

trees less than 10 cm in diameter were left on site. The

control units have received no treatment and are to be kept

free of any subsequent stand treatments. Fire suppression

activities are to continue in the area.

Total volume removed was 17.6 million board feet plus

an additional 62 thousand green metric-tons of biomass.

Due to the scale of the project, three field seasons were

required to complete mechanical treatments (1998, 1999,

and 2000). Prescribed fire was applied in October 2001.

Treated units ranged from 20- to 30-percent crown

cover post-treatment (excluding consideration of planned

openings, which had a cover of zero). Thinning treatments

reduced crown cover approximately 25 percent. Cover in

the controls ranged from 45 to 60 percent. For pine-emphasis treatments, the proportion of fir basal area was reduced

roughly 20 percent (fig. 2). In the large-tree treatments,

proportion of fir basal area was reduced about 7 percent,

on average.

Sampling Design

Sampling of understory vegetation consisted of an array

of six, 0.5 m2 plots located systematically (at 6-, 21-, 36-,

64-, 79- and 93-meter mark) along a 100 m transect. There

were 17 to 19 such transects in each treatment unit, with

each transect spaced on a systematic grid. Grid points are

surveyed at a 100 m square spacing and every other grid

point is sampled for understory vegetation. Thus the center

point of each transect was on a 141 m square spacing

throughout the treatment unit. Transects were oriented diagonally, with a random choice determining whether each

transect was NE/SW or NW/SE. At each of the sampling

300

Table 1—Pretreament quadratic mean diameter, basal area, stand density index 

(Reineke 1933), and density summaries for 20 stands in the Goosenest Adaptive 

Management Area study

Minimum 1st Quartile Median 3rd Quartile Maximum

QMD, cm 24.6 28.2 29.0 39.4 41.1

BA, m2/ha 26.6 30.3 37.0 42.9 58.3

SDI, trees/ha 474 523 689 822 1084

N, trees/ha 217 385 568 778 902

Table 2—Distribution of burn severity (percentage 

of area) following prescribed fire within each of the

burned units at the Goosenest Adaptive Management

Area

Burned units

Condition 3 6 13 15 17

Unburned openings 13 13 14 14 14

Light ground char 51 51 48 57 54

Moderate ground char 30 31 22 19 17

Deep ground char 6 5 16 10 15
301

plots, the crew recorded all species present on each plot and

estimated cover for the most common plant species. Trees

above 1.3 m in height were not included in the sample.

Understory vegetation was sampled between mid-May and

mid-July, 2003. A total of 79 species were observed on

2,142 fixed area sample plots (table 3). Reference for

species identification is Hickman (1993).

ANALYSIS

Species Richness

Stability of species richness was tested by using a bootstrap approach. Data were sampled from each of the treatment units, starting with an intensity of sample size of 5,

up to 100, in increments of 5. For each level of sampling

intensity, 500 samples were taken. The average species

richness was calculated for each unit at each level of sampling intensity. Treatment effects on species richness were

also analyzed using a Kruskal-Wallis (nonparametric) test. 

Species Frequency

Species distribution was tested by evaluating the frequency observed in the sampling frame. Average number of

species recorded within transects varies by treatment. This

is a standard one-way analysis of variance with contrasts

defined a priori for comparing

Treated vs. untreated

Thinned and burned vs. unburned

Thinned and burned vs. thinned only

Individual species trends in plot frequency were evaluated for several common understory species and species

groups (forbs, grasses, shrubs and trees). The grasses-group

included grass-like sedges (genus Carex). The index for

groups was calculated as the mean, over each transect, of

the number of species in each group in each 0.5 m2 plot.

This value was then averaged for the entire treatment unit. 

Frequency for individual species was calculated as the

sum over each transect, then averaged for the treatment

unit across grid points. Individual species considered were

white fir, bitterbrush, goldenbush and snowbrush. Other

species were present but in insufficient numbers to reveal

any trends.

RESULTS

The bootstrap evaluation of richness as a function of

sample size shows that richness is still increasing at sample

size of 100 (fig. 3). Although the number of species differs

between units, all show the same pattern, with increasing

richness through the entire range of sample sizes. This suggests that our samples (ranging in size from 102 to 114) 

of half square meter plots are inadequate to fully capture

species richness at this scale. That is, with a larger sample

size we would have observed a greater value for species

richness. To fully capture species richness, we need to either

increase sample size or area of the sample frame.

Furthermore, variability in richness is greater among

treated units. The range in richness values is less for the controls than for each of the other treatment units. The maximum for thinned and thinned-and-burned units was between

30 and 40, while the control maximum is less than 30.

With sample size nearly constant across our treatment

units, we considered richness conditional on the observed

sample size. Graphic analysis shows a trend toward slightly

lower values for control plots (fig. 4). However, a nonparametric Kruskal-Wallis test indicated no statistically significant effect of treatments on species richness (p-value =

0.648). 

Frequency analysis of variance for species groups (trees,

shrubs, grasses, and forbs) yielded few well-defined trends

(table 4). However, the mean index for tree species was

higher for control than treated (0.18 vs. 0.088) and higher

for unburned than burned (0.131 vs. 0.047). Also, the frequency of shrub species was higher for treated than control

units (0.40 vs. 0.15). When analyzed as a group, forbs and

shrubs had no significant differences in treatment means.

Only four of the individual species showed any significant (p-value < 0.10) difference in frequency response

(table 5). The analysis of variance for most species yielded

p-values greater than 0.50. 

Figure 2—Reduction in proportion of white fir basal area and post-treatment proportion of white fir.
The response of tree frequency is demonstrated primarily in white fir. Ponderosa pine regeneration was found

to be a relatively rare event at this early stage of the study.

White fir frequency was substantially reduced by both thinning and burning treatments (fig. 5). When expressed as

stocking percentage, white fir in the control was approximately eight times that found in the thinned and burned

units (table 6).

Snowbrush treatment effect was highly significant (table

5); control units had the lowest frequency of snowbrush

(fig. 5). Density in thinned and burned units averaged

roughly 40 times the density of controls (table 6). There

were no significant effects on goldenbush (p-value = 0.46).

Statistically significant treatment effects were found for

bitterbrush (p-value = 0.015). However, this finding is tempered by the pretreatment distribution of this species. An

analysis of pretreatment frequency for this species found

significant differences. Bitterbrush was more prevalent on

the large-tree emphasis treatment units both before and

after treatment.

Among the grasses, sedges and forbs, only groundsmoke

showed any significant treatment effect (p-value=0.02), with

an increase in frequency for all treated areas.

CONCLUSION

In general, observed changes in understory vegetation

were subtle. Effects of both thinning and prescribed fire

may take several years to fully develop. Understory species

were more evenly distributed within treated plots, and there

is some suggestion that species richness may also increase

in treated areas. With time, these responses may become

more striking, particularly with reapplication of treatments. 

302

Table 3—Most common plant species, by plant form, and frequency observed in 

2,142 sample plots on the Goosenest Adaptive Management Area study

Common Name Scientific Name Group Count

Miner’s lettuce Claytonia perfoliata Forb 114

Maiden blue-eyed Mary Collinsia parviflora Forb 438

Quill cryptantha Cryptantha affinis Forb 260

Squirreltail Elymus elymoides Forb 178

Groundsmoke Gayophytum diffusum Forb 588

Mountain violet Viola purpurea Forb 94

California needlegrass Achnatherum occidentale Grass 442

California brome Bromus carinatus Grass 71

Cheat grass Bromus tectorum Grass 4

Western fescue Festuca occidentalis Grass 33

Kentucky bluegrass Poa pratensis Grass 3

Long-stolon sedge Carex inops ssp. inops Grasslike 256

Ross’ sedge Carex rossii Grasslike 448

Bitter dogbane Apocynum androsaemifolium Shrub 72

Greenleaf manzanita Arctostaphyllos patula Shrub 79

Squawcarpet Ceanothus prostratus Shrub 67

Snowbrush Ceanothus velutinus Shrub 140

Goldenbush Ericameria bloomeri Shrub 144

Bitterbrush Purshia tridentata Shrub 40

Wax currant Ribes cereum Shrub 55

Creeping snowberry Symphoricarpos mollis Shrub 79

White fir Abies concolor Tree 205

Incense-cedar Calocedrus decurrens Tree 5

Ponderosa pine Pinus ponderosa Tree 26
303

Figure 3—Relation between species richness and number of sample plots for each of the treatment units (each unit is a separate line) in (A) control, 

(B) large-tree emphasis, (C) pine emphasis and, (D) pine emphasis with prescribed fire treatments.

Table 4—P-values associated with analysis of frequencies of species 

groups and specific, single degree-of-freedom contrasts. Significant 

(p-value < 0.10) comparisons are in italics

Contrasts Trees Shrubs Grasses Forbs

Pine vs. pine+fire 0.115 0.900 0.148 0.298

Treated vs. control 0.004 0.007 0.524 0.131

Burn vs. unburned 0.004 0.232 0.252 0.169

Overall treatment p-value 0.007 0.050 0.410 0.333
Richness in this forest type, and at these scales, requires

a more intense sampling method. A thorough sample of a

40-ha unit may not be feasible without a significant increase

in time and effort. Our sampling of this study area took a

two-person crew more than 10 weeks, effectively spanning

the growing season for many species. Because many observed

plants are ephemeral, results may be influenced by time of

measurement. At this scale, it is probably not possible, from

a practical perspective, to quantify richness without estimating the true value. Because richness is a value influenced

by rare events, larger plots and a larger sampling crew are

needed to accurately quantify this measure of diversity. 

Frequency values are not independent of plot size, 

and these plots are small for some classes of vegetation

(Bonham 1988: 91). Comparisons, therefore, with other

studies employing a different sampling strategy are not

possible.

White fir is a common understory species in our

untreated (control) units, however our treatments, particularly prescribed fire, have significantly reduced the occurrence of this species. This suggests favorable prospects for

keeping this species at reduced levels, particularly with

planned repeated applications of prescribed fire. 

304

Figure 4—Box plot of species richness over treatment; solid lines are quartiles and median,

treatment mean is dotted line.

Table 5—Results of ANOVA for individual species frequency, sorted by 

p-value; species not listed had p-values > 0.50

Treatment Error

Species M.S.a M.S. F P-value

Snowbrush 0.00197 0.000148 13.32 0.0001

White fir 0.00207 0.000230 9.01 0.0010

Bitterbrush 0.000699 0.000146 4.77 0.0147

Groundsmoke 0.00116 0.00267 4.36 0.0200

Squirreltail 0.000695 0.000345 2.01 0.1532

California brome 0.000126 0.000111 1.31 0.3653

California needlegrass 0.000511 0.000555 0.92 0.4538

Goldenbush 0.000269 0.000301 0.90 0.4641

a M.S. = mean square
305

Natural regeneration of ponderosa pine is largely absent

throughout the study area at this time, although survival of

planted openings is generally high. Since the openings were

ripped to a depth of approximately 20 cm prior to planting,

these openings are generally devoid of other vegetation at

the time our samples were taken.

As a group, shrubs responded positively to the treatments, particularly snowbrush. Results for bitterbrush, a

key browse species, were inconclusive. The study area is a

transition zone for the species, with observations only made

on 6 of the 20 treatment units, and all of these were at the

lowest elevations of the study. Since three of the large-tree

treatment units are in this lower elevational range, there is a

somewhat spurious treatment effect found in bitterbrush. 

The combination of burning and thinning in this study

produced a strong response in snowbrush. The combination

of fire and more open stand conditions created a favorable

environment for germination and growth. Snowbrush is

known to respond to burning (Halpern 1988). Existing plants

sprout vigorously after fire; seeds can persist in the soil for

long periods and germinate when favorable conditions are

presented (USDA 1988). Similar response to thinning and

burning has been shown elsewhere in pine forests of northeastern California (Borsting 2002). 

With the exception of groundsmoke, which increased 

in frequency in treated areas, grass and forb species did not

appear to respond significantly to thinning or prescribed fire

treatments at this early stage of the experiment. 

Figure 5—Frequency of white fir, snowbrush and groundsmoke related to treatment (control,

large-tree emphasis, pine emphasis and pine emphasis with prescribed fire).

Table 6—Plant stocking, expressed as a percentage of the area with

plants on a 0.5 m2 plot, ± standard error, by treatment

Treatment White fir Bitterbrush Snowbrush

Control 0.93 ± 0.16 0 0.02 ± 0.01

Large tree 0.63 ± 0.14 0.40 ± 0.18 0.22 ± 0.04

Pine emphasis 0.47 ± 0.07 0.01 ± 0.01 0.46 ± 0.06

Pine emphasis + fire 0.11 ± 0.04 0.01 ± 0.01 0.79 ± 0.17
ACKNOWLEDGMENTS

This paper is contribution no. 10 of the Goosenest

Adaptive Management Area Research Project, Pacific

Southwest Research Station, USDA Forest Service.

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1 Biologist, USDA Forest Service, Forestry Sciences Laboratory, P.O. Box 8089, Missoula, MT 59807, USA. Email: cstalling@fs.fed.us

Balancing Ecosystem Values Proceedings, Fire and Fire Surrogates

A Collaborative Approach to Forest Management: 

Using a Landscape-Level Dynamic Simulation Model as a Tool 

to Enhance Communication Among Diverse Landowners

Christine M. Stalling1

INTRODUCTION

Collaborative partnerships, strategic planning, and publicprivate cooperation have become prevalent in natural

resource management during the last decade. Wildland fuels

have been accumulating during at least the past 50 years due

in part to wildland fire management policies. As demonstrated by recent wildland fires, large fuel loads contribute

to intense fire behavior and increase resistance to control.

Consequently, property and natural resources have been

destroyed, costs of fire management have increased, fire

dependent ecosystems have deteriorated, and the risks to

human life continue to escalate. The Swan Valley in northwestern Montana is no exception. The threat of wildfire is

one of the many challenges facing the Swan Valley today.

The impacts of human population growth, private timber

agency land sales, threats to wildlife corridors due to

forestry practices and population growth, and fire in the

ABSTRACT

Forest management tools have evolved from stand-level, silvicultural applications to increasingly diverse tools addressing multiple scales of analyses and disciplines. Given the complexity of these multiple scales, successful communication

across all ownerships is necessary for effective land management applications. In this study, the utility of using the landscape dynamic simulation model SIMPPLLE (SIMulating Patterns and Processes at Landscape scaLEs) is tested as a science

communication tool emphasizing social values in a collaborative approach to fuels management. Landowners and stakeholders in the Swan Valley, northwestern Montana, will participate in workshops focusing on the use of modeling to help

visualize the effects of management activities on the Swan Valley landscape, both spatially and temporally. Methods of integrating and communicating ecological, social, and economic principles associated with the landscape will be applied using

the SIMPPLLE model in conjunction with support from the Swan Ecosystem Center (SEC). The SEC is a nonprofit citizen’s

organization whose mission is to maintain their community by focusing on partnerships that encourage sustainable use and

care of public and private lands in the Swan Valley. The “Upper Swan Valley Landscape Assessment,” coordinated by SEC,

serves as a guide to sound stewardship plans in the Swan Valley and will be used to provide information for model exercises.

KEYWORDS: Landscape, simulation model, collaboration, communication, management.

309

wildland-urban interface continue to present complex

issues for land managers. In addition, conflicting views

regarding desired future conditions on the landscape provide

barriers to land management. The Swan Valley community

is well represented by public and private interests and is

closely involved in managing their valley for “the ecological

integrity of the land and the resources it supports” (Swan

Ecosystem Center 2004). Successful, science-based management in such a community can only be accomplished

when all landowners and stakeholders understand the reason

for any proposed plan of action and agree with the planned

actions. Communication must occur between managers,

researchers, landowners, and stakeholders before active

management can take place.

Communication is more complex than simply sending a

message to a receiver who then assimilates the information;

it is a complex process in which the receiver interprets the
message based on personal experiences (Weber and Word

2001). Because groups and individuals learn and understand

in many different ways, it is necessary to adjust methods of

communication accordingly. The level of pre-existing knowledge within a group can influence whether a certain approach

used to communicate science and the associated impacts of

management activities will succeed or fail. Studies in adult

learning show that a hands-on approach is an effective

method for reaching adult audiences (Parkinson et al. 2003).

Shindler and Toman (2003) indicate “...effective, inclusive

communication strategies must not only provide information but also focus on how people come to understand forest

conditions...” Despite the substantial knowledge base of

ecological and socioeconomic values and the use of models

and modeling approaches to represent these phenomena, the

ability of resource managers to successfully communicate

this knowledge is lacking. 

Land managers recognize the need to schedule and

evaluate management activities across multiple ownerships

when planning management applications on landscapes

(Bettinger and Sessions 2003). Yet, environmental decisionmaking is a complex endeavor that requires an integrated

and multidisciplinary approach, which includes public 

participants and stakeholder groups that can affect or be

affected by management decisions (Videira et al. 2003). In

order for all stakeholders to play an active and informed

role in any collaborative planning effort, they must first

understand the basic ecological science related to vegetation change and the spatial relationships of vegetation and

processes such as fire across landscapes. Thus, landowners

and stakeholders would benefit from tools to help them better understand the links between the patterns and processes

of the larger landscape and their influences on the ecology

of land units at smaller scales, such as the stand level. The

landscape dynamic simulation model, SIMPPLLE (Chew

et al. 2004), has potential as a tool for communicating the

science of landscape change and the influences of natural

processes and management treatments both temporally and

spatially. Landowners and stakeholders in the Swan Valley

are engaged in the ecology and management of their landscape and are interested in exploring the use of landscape

level modeling to help develop their management plans.

The research proposed in this paper is designed to explore

the applicability of the SIMPPLLE model as a tool to aid

communication and collaboration of landscape level management alternatives among residents and stakeholders in

the Swan Valley.

Some funding for this project was provided to the Swan

Ecosystem Center (SEC) through a challenge cost share

agreement with the Flathead National Forest (funded by the

U.S. Forest Service Washington Office). More funding is

being sought through the Joint Fire Sciences Program for

an 18-month study period in which the model will be introduced to members of the Swan Valley community; workshops and/or interviews will be conducted to gain a baseline

measure of landscape-level knowledge among participants;

management plans will be developed by using the model

and data representative of the Swan Valley; and interviews/

workshops will then be used as a follow-up to measure

whether the model was a useful tool in this process.

OBJECTIVES

The utility of a landscape model will be tested as a tool

to communicate natural resource management concepts and

to enhance stakeholder participation in collaborative planning efforts, specifically for the identification of wildland

fuel treatments in the Swan Valley, western Montana. The

approach is first to test the current version of the SIMPPLLE

model as a science communication tool among stakeholders including private landowners, Montana Department of

Natural Resources and Conservation (DNRC), the Flathead

National Forest, and Plum Creek Timberlands; second to

test the utility of the model as a tool to facilitate a collaborative approach to wildland fuels management; and third to

develop a land management plan for a community forest in

the Swan Valley by using the model to consider influences

of natural processes and management treatments on the

landscape beyond the community forest. Workshops and

interviews will be used to gauge the level of participant

understanding of the basic science related to vegetation

change, fire, and population influences on management

issues before and after running the model. Participants will

then use the model to develop wildland fuel treatment alternatives for the Swan Valley; interviews will follow to analyze whether the model helped participants reach agreement

on the management plans.

The upper Swan Valley includes approximately 100 000

hectares of federal, state, and private land. The checkerboard ownership is distributed between the Flathead National

Forest (67 percent), Plum Creek Timber Company (24 percent), nonindustrial private (9 percent), and the DNRC (less

than 1 percent); private and corporate lands occur primarily

in the valley bottom while public lands are in the upper

elevation and wilderness areas (Swan Ecosystem Center

2004). This heavily forested landscape, composed of a narrow valley through which the Swan River winds, is surrounded by the Mission Mountain Wilderness directly west

and the Swan Range to the east. The valley is characterized

310
by ecologically significant wetlands, threatened and endangered species habitat, wildlife connectivity, and high natural

biodiversity. The town of Condon is centrally located in the

upper Swan Valley; approximately 550 permanent valley

residents live in Condon and the surrounding area. A 1993

community profile (Cestero and Belsky 2003) describes

the permanent residents of the upper Swan Valley as a group

with diverse interests: approximately 25 percent of the

population is struggling to make a living by holding more

than one job, while the fastest growing part of the population is retired. With the majority of ownership held by nonresidents (Flathead National Forest and Plum Creek Timber

Co.), declining timber harvests influencing local economics, and increasing interest in the ecology and management

of the Swan Valley and associated wildlands, residents of

the Swan Valley have been experiencing substantial “growing pains” over the past decade. In response to the contentious economic and environmental issues associated with

these growing pains, an ad hoc citizen’s group was formed

in 1990. In 1996, the Swan Citizen’s Ad Hoc Committee

developed the Swan Ecosystem Center, a nonprofit organization located in a former Forest Service building. The

purpose of the center is to “represent the community in

partnership with the Forest Service” (Cestero and Belsky

2004).

The Swan Ecosystem Center is important to the upper

Swan Valley community because the organization provides

a forum for residents and stakeholders to discuss ecological,

social, and economic issues. Forest stewardship and timber

management practices were tested by members of the SEC

in conjunction with the Flathead National Forest in a ponderosa pine restoration project on SEC land; long-term

monitoring of the site by SEC committee members continues

and lessons learned from the experiment continue to provide

educational opportunities. This project and a similar one on

private land were used to illustrate the links between community well-being and forest health. During the restoration

process and subsequent monitoring, resident volunteers have

gained immeasurable knowledge of fire ecology, forest

stewardship logging, and Forest Service regulations in the

design and implementation of the project. 

Through these community projects, civil dialogue and 

a growing trust has been built among former adversaries.

Residents feel that interactions with Plum Creek and the

Forest Service, with SEC often facilitating, indicate a willingness to address residents’ concerns; residents now feel

they are gaining greater influence in valley land management

decisions (Cestero and Belsky 2003). The SEC’s role is

important to this study because of the trust they have already

established in the Swan Valley community; they will provide

guidance in the participant selection process as well as data

collection and project support.

Knowledge of ecology and management of forests at the

stand level is evident among members of the Swan Valley

community. The community’s commitment to managing

the upper Swan Valley as an ecosystem is outlined in the

landscape assessment (Swan Ecosystem Center 2004). This

study will provide a possible approach to moving from

stand-level ecology and management practices to the

broader scale interactions and connectivity of individual

vegetation units with the landscape-level patterns and

processes that are shaped by fire, insects and disease events

as well as prescribed treatments.

METHODS

Workshops and interviews will be used to gauge the level

of participant understanding of the basic science related to

vegetation change, fire, and population influences on management issues before and after running the model. Participants will then use the model to develop fuel treatment

alternatives for the Swan Valley; interviews will follow to

analyze whether the model enhanced participation and

thereby helped participants reach agreement on the management plans.

MODEL APPROACH

An integrative approach to landscape level planning and

management should be accomplished by bringing together

knowledge from many disciplines. SIMPPLLE is a management tool developed to help land managers integrate the

best available knowledge of vegetation change resulting

from disturbance processes such as fire, insects, and diseases

as well as fire suppression and management treatment

activities (Chew et al. 2004). The model uses landscapelevel vegetation data to represent vegetation change as a

result of the interacting disturbance processes and management actions. The model’s spatial link to geographic information systems (GIS) and the dynamic approach to modeling

landscapes help users visualize how a landscape can change

over time and space with and without the influence of management applications. The model has been used as a tool

by natural resource managers and researchers but its utility

with nonexperts has not been tested.

311
COMMUNICATION 

AND COLLABORATION

Public participation is critical to sound environmental

policy and decisionmaking (Videira et al. 2003). An informed

public is more capable of meaningful participation than a

public that bases decisions on other criteria such as trust,

shared community knowledge, or rumors. The communication process between expert and nonexpert groups may or

may not result in greater understanding of the environmental

issues that a community must address. Experts can raise

public awareness of environmental issues by acknowledging and addressing the often-implicit assumptions that block

understanding of science by less informed members of the

public (Weber and Word 2001). 

To communicate the science of landscape-level management, it is necessary to understand current perceptions and

existing knowledge in a community of landowners and

stakeholders. One-on-one interviews will be conducted with

participants selected by the Swan Ecosystem Center for this

study to establish a baseline level of understanding of forest

management and ecology held by this group. Interview

questions will be developed with help from Dr. Kari

Gunderson, Resource Management Scientist with the Aldo

Leopold Wilderness Research Institute, and Dr. Jill Belsky,

Professor of Rural and Environmental Sociology at the

University of Montana, Missoula. Following these interviews,

I will lead a 2 to 3 hour workshop at the SEC in which

modeling exercises will be used to display how SIMPPLLE

represents landscape change spatially and temporally. During

the workshop, discussions and questions regarding model

approach, ecology, and management issues will be addressed

and a follow-up interview will be conducted to establish

whether the model was helpful as a tool to aid in communicating issues and concerns among participants.

I will lead a second 2 to 3 hour workshop in which the

model will be used to help the same participants develop

management alternatives for fire risk reduction, maintenance

of wildlife corridors, influences of private timber company

land sales, and desired future conditions. Follow-up interviews will be conducted to establish whether the model

was helpful in bringing the participants to consensus in

developing the proposed management alternatives. If participants are able to come to consensus on a management plan

for their community forest, those alternatives will be applied

and monitored on the community forest.

PRODUCTS

Two publications will be developed; one will detail an

approach to testing a landscape dynamic simulation model

as a tool to communicate science-based concepts associated

with dynamic landscapes and fuel treatments to community

members and stakeholders. A second publication will detail

the use of a landscape dynamic simulation model as a tool

for collaborative planning of fuels treatments within a landscape assessment framework.

The SIMPPLLE model is available for use and can be

downloaded from a publicly accessible Internet website or

an ftp site. Installation instructions exist for a wide variety

of platforms. As a result of this study, it will be possible to

improve system application to a broader client base.

ACKNOWLEDGMENTS

Anne Dahl, executive director of the Swan Ecosystem

Center, continues to provide invaluable cooperation and

support for this project. Kari Gunderson, resource management specialist for the Aldo Leopold Wilderness Research

Institute, continues to donate her time and expertise to this

project as well as the myriad needs of the Swan Valley.

Jimmie Chew, forester with the Rocky Mountain Research

Station and developer of the SIMPPLLE model, continues

to provide expertise toward this research project.

REFERENCES

Bettinger, P.; Sessions, J. 2003. Spatial forest planning. 

Journal of Forestry. 101(2): 24-29.

Cestero, B.; Belsky, J.M. 2003. Collaboration for community and forest well-being in the upper Swan Valley,

Montana. Forest communities, community forests.

Lanham, MD: Rowman and Littlefield: 149-169.

Chew, J.D.; Stalling, C.M.; Moeller, K. 2004. Integrating 

knowledge for simulating vegetation change at landscape scales. Western Journal of Applied Forestry.

19(2): 102-108.

Parkinson, T.M.; Force, J.E.; Smith, J.K. 2003. Hands-on 

learning: its effectiveness in teaching the public about

wildland fire. Journal of Forestry. 101(7): 21-26.

312
Shindler, B.; Toman, E. 2003. Fuel reduction strategies in 

forest communities: a longitudinal analysis of public

support. Journal of Forestry. 101(6): 8-15.

Swan Ecosystem Center. 2004. Upper Swan Valley landscape assessment. Swan Valley Ecosystem Management

& Learning Center, Inc. Unpublished report. On file

with: C. Stalling, Forestry Sciences Lab, P.O. Box

8089, Missoula, MT 59807, USA.

Videira, N.; Antunes, P.; Santos, R.; Gamito, S. 2003. 

Participatory modeling in environmental decisionmaking: the RIA Formosa Natural Park case study.

Journal of Environmental Assessment Policy and

Management. 5(3): 421-447.

Weber, J.R.; Word, C.S. 2001. The communication process 

as evaluative context: What do nonscientists hear when

scientists speak? BioScience. 51(6): 487-495.

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1 Research Forester, USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 1401 Gekeler Lane, LaGrande, OR 97850, 

USA. Email for corresponding author: ayoungblood@fs.fed.us

2 Assistant Site Manager, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA

3 Research Ecologist, U.S. Geological Survey, Sequoia and Kings Canyon Field Station, HRC 89 Box 4, Three Rivers, CA 93271, USA

4 Research Ecologist, USDA Forest Service, Southern Research Station, Forestry Sciences Laboratory, 320 Green Street, Athens, GA 30602, USA

5 Assistant Professor of Fire Sciences, Dept. of Environmental Science, Policy, and Management, 151 Hilgard Hall #3110, University of California 

Berkeley, Berkeley, CA 94720, USA

6 Research Forester, USDA Forest Service, Southern Research Station, 239 Lehotsky Hall, Clemson, SC 29634, USA

7 Research Forester, USDA Forest Service, Northeastern Research Station, Forestry Sciences Laboratory, 359 Main Road, Delaware, OH 43015

Balancing Ecosystem Values Proceedings, Fire and Fire Surrogates

Implementation of the Fire and Fire Surrogate Study—

A National Research Effort to Evaluate the Consequences 

of Fuel Reduction Treatments

Andrew Youngblood,1 Kerry L. Metlen,2 Eric E. Knapp,3 Kenneth W. Outcalt,4

Scott L. Stephens,5 Thomas A. Waldrop,6 and Daniel Yaussy7

INTRODUCTION

Many fire-dependent forests—especially those with 

historically short-interval, low- to moderate-severity fire

regimes—contain more small trees and fewer large trees,

have higher fuel loads, and greater fuel continuity compared to conditions under historical fire regimes (Agee

1993, Arno et al. 1997, Barden 1997, Caprio and Swetnam

1995, Cowell 1998, Kilgore and Taylor 1979, Swetnam

ABSTRACT

Many fire-dependent forests today are denser, contain fewer large trees, have higher fuel loads, and greater fuel continuity than occurred under historical fire regimes. These conditions increase the probability of unnaturally severe wildfires.

Silviculturists are increasingly being asked to design fuel reduction treatments to help protect existing and future forest

structures from severe, damaging, and expensive wildfires. The consequences of replacing the historical role of fire with

fuel reduction treatments, such as underburning with prescribed fire, cutting with mechanized equipment like a feller-buncher,

or a combination of both, remain largely unknown and require innovative operational-scale experiments for improved understanding. The Fire and Fire Surrogate (FFS) study is a large manipulative experiment designed by an interdisciplinary team

of federal agency and academic researchers to address ecological processes, economic viability, and operational consequences

of different fuel reduction treatments. Replicated at 13 installations on federal and state lands extending from the eastern

Cascade Range in Washington to the southern coastal plain in Florida, this study is likely the largest operational-scale experiment ever funded to test silvicultural treatments designed to balance ecological and economic objectives for sustaining

healthy forests. This paper describes the study objectives and research approach, provides a status of work at the different

sites, and presents initial results of changes in stand structure and related understory vegetation as an example of the broad

comparisons that this study allows. These initial among-site comparisons highlight the potential value of network-wide

meta-analyses for determining the scale at which common themes emerge.

KEYWORDS: Fire and Fire Surrogate study, fuel reduction, overstory-understory interactions, meta-analysis.

315

1990, Taylor and Skinner 1998, Van Lear and Waldrop 1989,

Waldrop et al. 1987, Yaussy and Sutherland 1994). These

conditions are the result of fire exclusion and suppression,

past livestock grazing and timber harvests, tree recruitment

after farm abandonment (especially in the southern United

States), and changes in climate (Arno et al. 1997, Skinner

and Chang 1996). Collectively, these conditions contribute

to a general deterioration in forest ecosystem integrity and

an increase in the probability of unnaturally severe wildfires
(Stephens 1998). Silviculturists are increasingly being asked

to design fuel reduction treatments that reduce the stand

basal area and the density of small trees, remove fire-sensitive trees, reduce the accumulation of woody debris, and

increase the height to live crowns to help protect these forests

from severe wildfire and at the same time meet a host of

other resource objectives. Strategies for managing forest

fuels to reduce the incidence of these expensive and damaging wildfires include underburning with prescribed fire,

cutting live and dead trees and removing logs with mechanized equipment like feller-bunchers, or a combination of

both. The consequences of implementing these strategies

remain largely unknown. Innovative operational-scale experiments that evaluate the effects of alternative management

practices involving fire and mechanical or manual surrogates

for natural disturbance events are essential for improved

understanding of management decisions. 

A team of federal, state, university, and private scientists

and land managers designed the Fire and Fire Surrogate

(FFS) study, an integrated national network of long-term

studies, with support from the USDA/USDI Joint Fire

Science Program and the national Fire Plan. The national

network currently includes 13 sites on federal and state

lands extending from the Cascade Range in Washington to

Florida (table 1). These 13 sites represent ecosystems with

frequent, low-severity natural fire regimes. At each site, a

common experimental design was used to facilitate broad

comparison of treatment effects. This FFS network likely

represents the largest operational-scale experiment ever

funded to test silvicultural treatments designed to balance

ecological and economic objectives for sustaining healthy

forests. Details of the network and links to individual sites

are available at the web site http://www.fs.fed.us/ffs/. In

this paper, we report on the study objectives and research

approach, provide a status of work at the different FFS sites,

and present initial results of changes in stand structure and

related understory vegetation for a subset of the sites.

STUDY OBJECTIVES OF THE FIRE 

AND FIRE SURROGATE STUDY

The FFS study was designed to quantify the ecological

and economic consequences of fire and fire surrogate treatments across a number of forest types and conditions in the

United States. Specific objectives are listed below: 

1. Quantify the initial effects (first 5 years) of fire and fire

surrogate treatments on specific core response variables

within the disciplines of vegetation, fuel and potential

fire behavior, soils and forest floor, wildlife, entomology,

pathology, and treatment costs and utilization economics.

2. Establish and maintain an integrated national network 

of long-term interdisciplinary studies using a common

“core” design that facilitates broad applicability of

results yet allows each site within the national network

to be independent for statistical analyses and modeling,

and allows flexibility for addressing locally-important

issues.

3. Designate FFS research sites as demonstration areas 

for technology transfer to professionals and for the 

education of students and the public.

4. Develop an integrated and spatially-referenced database and archive data from all network sites; facilitate

developing interdisciplinary and multiscale models, 

and integrate results across the network.

5. Over the long term, continue to monitor the results 

of treatments, repeat treatments where appropriate,

develop and validate models of ecosystem structure 

and function, and refine recommendations for ecosystem management. 

RESEARCH APPROACH

The FFS study is implemented on land administered by

the USDA Forest Service, the USDI National Park Service,

various university experimental forests and education centers,

state parks, and state forests. The core experimental design

for the FFS study includes common treatments, similar

treatment replication and plot sizes, and common response

variables for all research sites in the network. The four

treatments used at 12 of the 13 sites include (1) untreated

control, (2) prescribed fire only, with periodic repeated

burns, (3) mechanical thinning, with periodic repeated thinning, and (4) mechanical thinning followed by prescribed

fire, with this combination repeated as necessary. Treatments

at the Sequoia National Park site consisted of an untreated

control, an early-season burn, and a late-season burn, which

are the principal landscape-scale treatment options on lands

managed by the National Park Service. The FFS treatments

span a range of realistic management options, and they likely

will provide a range of ecological effects. Implementation

of the active (noncontrol) treatments at each site was guided

by a desired future condition or target stand condition uniquely

defined for each site such that, if impacted by a head fire

under 80th percentile weather conditions, at least 80 percent

of the basal area of overstory trees would survive. Treatments

were replicated at each of the sites at least three times in

either a completely randomized or randomized block design.

Each treatment unit was at least 10 ha and surrounded by a

316
similarly treated 50-m buffer. Assignment of treatment to

each of the units was completely random. This requirement

for randomization is central to the conduct of science but

has not often been a part of large operational-scale studies

involving land-management agencies. 

Core variables encompassed several broad disciplines,

including vegetation, fuel and potential fire behavior, soils

and forest floor, wildlife, entomology, pathology, and treatment costs and utilization economics (FFS Study Plan 2001).

Some 400 response variables were selected for monitoring,

with the majority spatially referenced to a 50-m square grid

of permanent sample points established and maintained in

each treatment unit.

Funding for the FFS has come from home institutions

and agencies, the USDA through a National Research Initiative competitive grant, the National Fire Plan, and primarily the Joint Fire Science Program.

The FFS study has three organizational tiers. The first

tier is site leaders or managers who ensure uniformity of

layout and implementation across all disciplines at a single

site. The site managers, along with group leaders for the

study disciplines (entomology, economics, fuels, pathology,

soils, vegetation, and wildlife) belong to the Science and

Management Integration Committee (SMIC), the second tier

in the organization. The third tier is a five-member Executive

Committee (a national network manager, two disciplinary

group leaders, and two site managers) selected by the SMIC.

Initially, the SMIC developed comprehensive study plans

guiding study implementation at each site, noting any justifications for and deviations from the agreed-upon national

FFS standard in implementation or monitoring. In addition,

the SMIC is responsible for ensuring that (1) site-level

studies are progressing according to project guidelines, (2)

data collection protocols and analysis remain consistent and

state-of-the-art, (3) data are properly archived and managed,

and (4) integration is occurring at all levels. Site managers

have responsibility for ensuring data are collected appropriately and are maintained in local databases, while the

SMIC oversees the creation of a central national FFS database. The Executive Committee is responsible for project

oversight, distribution of funds, and reporting to the Joint

Fire Science Program Governing Board.

CURRENT STATUS OF WORK 

AT FFS RESEARCH SITES

Most of our field effort began in early 2000. The initial

set of treatments has been completed at 11 of the 13 sites

(table 1), and measurement of responses is ongoing. Prescribed fire for fuel reduction has been used at all sites;

however, the season of application, intensity of burn, and

frequency of burn varied across sites. For example, even

though the Hungry Bob site in northeastern Oregon and the

Lubrecht Forest site in western Montana have similar stand

histories, stand structure, and vegetation composition, burns

at Hungry Bob were conducted in October, whereas burns

at Lubrecht Forest were conducted in May and June. Burns

at the Southern Coastal Plain site in Florida were scheduled

as an early-season treatment on a 3-year return interval; the

second iteration of burns was completed early in the spring

2004. At most sites, mechanical fuel treatments generally

317

Table 1—Location and current status of sites in the Fire and Fire Surrogate study network

Treatment

FFS site Forest type Location year

Blodgett Ponderosa pine and white fir Central Sierra Nevada, California 2002

Hungry Bob Ponderosa pine and Douglas-fir Blue Mountains, northeastern Oregon 1998-2000

Jemez Mountains Ponderosa pine Northern New Mexico In progress

Lubrecht Forest Ponderosa pine and Douglas-fir Northern Rockies, western Montana 2002

Mission Creek Ponderosa pine and Douglas-fir Central Cascades, Washington In progress

Ohio Hills Mixed oaks Southern Ohio 2001

Sequoia Ponderosa and sugar pine, white fir Southern Sierra Nevada, California 2002

Solon Dixon Longleaf pine South central Alabama 2003

South Carolina Piedmont Loblolly and shortleaf pine Northwestern South Carolina 2001-2002

Southern Appalachian Hickory, oaks, and shortleaf pine Southwest North Carolina 2002-2003

Southern Cascades Ponderosa pine Southern Cascades, northern California 2000-2002

Southern Coastal Plain Longleaf and slash pine Central Gulf Coast, Florida 2001

Southwest Plateau Ponderosa pine Northern Arizona 2003
consisted of removing small-diameter stems in a low thinning by using a combination of single-grip harvester and

forwarder. All trees to be harvested were marked prior to

harvest activities. At the Southern Coastal Plain site, the

accumulation of fuels was in understory layers and consisted

primarily of herbaceous matter rather than overstory layers;

therefore, the mechanical treatment employed a roller drum

chopper. At Blodgett in California, large stem diameters

required an initial commercial thinning from below by handfalling, with logs yarded to landings by rubber-tired skidders. Next, live and dead understory stems were masticated

by using an excavator with a disk-type cutter head, with

masticated material left on site. In all but the Ohio, Alabama,

North and South Carolina, and Florida sites where litter

decomposition occurs rapidly, the combination treatment of

mechanical thinning followed by prescribed fire required

waiting a full season for activity fuels to cure before burning.

Pretreatment data has been collected on all sites, as has

most of the first year post-treatment data. Our first challenge within the FFS network was to portray immediate or

short-term changes resulting from treatments. These shortterm changes are likely of general interest to managers concerned with how conditions changed as a result of treatment.

To answer this question, we used both pre- and post-treatment data and focused on the difference between pre- and

post-treatment values. We also used pretreatment data as a

covariate. At the site level, univariate analysis of variance

for the change in each response variable was a first means

of evaluating treatment differences. The second challenge

is to predict longer term differences among treatments. These

long-term differences are likely of general interest to managers concerned with how response variables change over

time in response to the treatments; some Southern sites

could also consider how the chosen variables change in

response to multiple entries. To answer these longer term

questions, pretreatment data is likely of little benefit. At

this time, our effort in the FFS network has been confined

to addressing the first challenge; over time, we will transition to considering the second challenge. 

Because typical univariate analyses test a single potential

causal pathway among variables through the direct effect

of each predictor, our understanding of the overall system

complexity is limited to the number of predictors we examine. In addition to univariate analyses, we intend to use

multivariate ordination techniques such as nonmetric multidimensional scaling (NMS) and indicator species analysis

(McCune and Grace 2002) for comparing species composition across treatments. A path analysis technique being

considered for both site-level and network-level analysis

uses indirect effects in structural equation modeling, and

may help elucidate previously unrealized relationships

(Quinn and Keough 2002). Finally, the SMIC recognized at

the onset that the strength of the FFS network could best be

realized through the calculation of effect sizes in a metaanalysis. 

PRELIMINARY EVALUATION 

OF CORE RESPONSE VARIABLES

We began assessing the results of treatments the first

growing season after full implementation of all treatments

at each site. One initial question we addressed was the

degree to which the active treatments (prescribed fire,

mechanical thinning, and the combination of prescribed

fire and mechanical thinning) resulted in similar stand

structure. Based on analysis of variance, our active treatments resulted in a reduction in basal area at the Blodgett,

Hungry Bob, Lubrecht Forest, Ohio Hills, and South

Carolina Piedmont sites (p < 0.05) (table 2). The reduction

was generally one-third to one-half of pretreatment basal

area. 

Another important indication of treatment success is 

the difference in height to live crown, or the height of the

lower live branches, because this metric influences the

transition of surface fire into tree crowns. Prescribed fire

often kills small trees and prunes lower branches or scorches

the lower crown of larger trees, whereas mechanical treatments can be more selective in removing only the small

trees. Burning significantly increased the height to live

crown (p < 0.05) at two sites in the western United States

(Hungry Bob and Sequoia), but not in two sites in the eastern United States (Ohio Hills and South Carolina Piedmont)

(table 2). Fuel types and pretreatment crown closure likely

are responsible for the lack of treatment effects on lower

crown heights at our southern and eastern sites. Surface

fuels decay readily in the high moisture regimes of the

Ohio, Alabama, North and South Carolina, and Florida

sites, and a greater proportion of the material that burns is

live understory compared to more western sites. In addition, the greater pretreatment height to base of live crown

(table 3) suggests that self-pruning of lower branches occurs

more frequently at these sites, restricting lethal heat to the

lower live tree canopies 

Our initial results of changes in understory (non-tree)

species richness were highly variable (table 2). The lack of

universally significant differences between treatments lends

support to the hypothesis that sites dominated by natural

high-frequency, low-severity fire regimes typically contain

plant communities that undergo little floristic change after

treatments modeled on historical fire disturbance (Metlen

et al. 2004).

318
Finally, log density was selected as one metric for

assessing the reduction in ground fuels, along with more

traditional measures of volume and mass of litter and duff

components, because log density has direct implications for

changes in wildlife habitat values. Our first-year assessment indicated a significant reduction of log density with

active treatment at Hungry Bob (p = 0.003) (table 2) with

burn units containing few logs compared to thinned units.

At other sites, log number did not change significantly with

treatments. This likely is due to the propensity of fire to

reduce the volume and mass, but not totally consume many

downed logs, especially if the burns are conducted when

moisture content within logs is relatively high. The number

of downed logs likely will change over time at all sites as

recently killed trees gradually fall to the forest floor.

Our efforts to date have focused on analyzing the individual site and building the network database to facilitate

cross-site comparisons by using meta-analysis techniques.

For example, we conducted a meta-analysis comparing the

live crown height in first-year postburn units with live

crown height in first-year control units from six sites. We

used MetaWin version 2 (Rosenberg et al. 2000) with

means and standard deviation data to calculate Hedges’ d

effect size and nonparametric estimates of the sampling

variances for each study based on a fixed effects model.

Nonparametric variances were calculated because they may

be less constrained by the assumptions based on large sample sizes (Rosenbery et al. 2000). The confidence interval

bounding the overall effect size was calculated based on

999 iterations of resampling. Our preliminary meta-analysis failed to indicate a significant network-wide treatment

effect (an increase in height to live crown); the overall effect

size was 0.4067 with a confidence interval spanning 0.0

(table 3). Yet significant and meaningful differences are

anticipated by the third year post-treatment as lower crowns,

once scorched by burning, continue to die back. These conflicting results from individual sites draw attention to the

value of the FFS study as a large-scale experiment and suggest the value of meta-analysis across the network. Metaanalysis may be useful for determining which variables show

similar response across sites, which variables require local

interpretation, and the scale at which common themes

emerge.

ACKNOWLEDGMENTS

This research was funded in part by the U.S. Joint Fire

Science Program. This paper is contribution number 55 of

the National Fire and Fire Surrogate Study (FFS).

319

Table 2—Significance of pairwise orthogonal contrasts (planned a priori) after univariate analysis of variance for

the change in basal area, post-treatment lower crown height, post-treatment understory vascular species richness, 

and log density for selected Fire and Fire Surrogate study sites

South Southern

Hungry Lubrecht Carolina Coastal

Blodgett Bob Forest Ohio Hills Piedmont Plain

Change in basal area (m2-ha-1)

Control vs. three active treatments 0.001 0.001 0.001 0.001 0.011 NS

Burn or thin vs. combined thin and burn .115 .370 .001 .004 .053 NS

Burn vs. thin .072 .015 .004 .001 .974 NS

Lower crown height (m)

Control vs. three active treatments NA .004 .011 .899 .277 NS

Burn or thin vs. combined thin and burn NA .057 .015 .359 .077 NS

Burn vs. thin NA .017 .102 .788 .575 NS

Understory species richness (species·m-2)

Control vs. three active treatments NA .107 .683 .001 .859 NS

Burn or thin vs. combined thin and burn NA .666 .044 .024 .786 NS

Burn vs. thin NA .748 .014 .026 .502 NS

Log density (number·ha-1)

Control vs. three active treatments NA .003 NS NA .761 NS

Burn or thin vs. combined thin and burn NA .066 NS NA .383 NS

Burn vs. thin NA .001 NS NA .478 NS

• NA = Data not currently available for analysis.

• NS = Analysis of variance indicated no treatment effect, therefore contrasts unwarranted.
REFERENCES

Agee, J.K. 1993. Fire ecology of Pacific Northwest forests. 

Washington, DC: Island Press. 493 p.

Arno, S.F.; Smith, H.Y.; Krebs, M.A. 1997. Old growth 

ponderosa pine and western larch stand structures:

influences of pre-1900 fires and fire exclusion. Res.

Pap. INT-RP-495. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain Research

Station. 20 p.

Barden, L.S. 1997. Historic prairies in the Piedmont of 

North and South Carolina, USA. Natural Areas Journal.

17(2): 149-152.

Caprio, A.C.; Swetnam, T.W. 1995. Historic fire regimes 

along an elevational gradient on the west slope of the

Sierra Nevada, California. In: Brown, J.K.; Mutch, R.W.;

Spoon, C.W.; Wakimoto, R.H., tech. coords. Fire in

wilderness and park management: proceedings of a

symposium. Gen. Tech. Rep. INT-320. Ogden, UT: 

U.S. Department of Agriculture, Forest Service,

Intermountain Research Station: 173-179.

Cowell, C.M. 1998. Historical change in vegetation and 

disturbance on the Georgia Piedmont. American

Midland Naturalist. 140: 78-89.

Fire and Fire Surrogate [FFS] Study Plan. 2001. A national 

study on the consequences of fire and fire surrogate

treatments. U.S. Department of the Interior, U.S. Department of Agriculture, Joint Fire Science Program.

www.fs.fed.us/ffs/ (17 November 2004).

Kilgore, B.M.; Taylor, D. 1979. Fire history of a sequoia 

mixed conifer forest. Ecology. 60(1): 129-142.

McCune, B; Grace, J.B. 2002. Analysis of ecological communities. Gleneden Beach, OR: MjM Software Design.

300 p.

Metlen, K.L.;Fiedler, C.E.; Youngblood, A. 2004. 

Understory response to fuel reduction treatments in the

Blue Mountains of northeastern Oregon. Northwest

Science. 78: 175-185.

Quinn, G.P.; Keough, M.J. 2002. Experimental design and 

data analysis for biologists. Cambridge University

Press. 537 p.

Rosenberg, M.S.; Adams, D.C.; Gurevitch, J. 2000. 

MetaWin: Statistical software for meta-analysis. Version

2. Sunderland, MA: Sinauer Associates. 128 p.

Skinner, C.N.; Chang, C. 1996. Fire regimes, past and present. In: Sierra Nevada Ecosystem Project: Final report

to Congress. Vol. II. Assessments and Scientific Basis

for Management Options. Wildland Resources Center

Report No. 37. Davis: Centers for Water and Wildland

Resources, University of California: 1041-1069.

Stephens, S.L. 1998. Effects of fuels and silvicultural treatments on potential fire behavior in mixed conifer forests

of the Sierra Nevada, CA. Forest Ecology and

Management. 105: 21-34.

320

Table 3—Results of a meta-analysis comparing the first-year post-treatment height to live crown for control and 

burn only treatments at selected Fire and Fire Surrogate study sites

Effect size

Site Mean height, control Mean height, burn (Hedges’ d) Nonparametric variance

Blodgett 7.5 7.4 -0.1358 0.6667

Hungry Bob 3.3 7.3 1.6667 .5000

Lubrecht Forest 8.1 7.4 -.2423 .6667

Sequoia 4.7 9.8 1.6543 .5000

South Carolina Piedmont 11.2 11.0 -.1753 .6667

Southern Coastal Plain 12.4 10.3 -1.3596 .7500

Mean effect size 95% confidence interval

0.4067 -0.413 to 1.226
Swetnam, T.W. 1990. Fire history and climate in the southwestern United States. In: Krammes, J.S., tech. coord.

Effects of fire management of southwestern natural

resources: Proceedings of a symposium. Gen. Tech.

Rep. RM-191. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain Forest 

and Range Experiment Station: 6-17.

Taylor, A.H.; Skinner, C.N. 1998. Fire history and landscape dynamics in a late-successional reserve, Klamath

Mountains, California, USA. Forest Ecology and

Management. 111: 285-301.

Van Lear, D.H.; Waldrop, T.A. 1989. History, use, and 

effects of fire in the Appalachians. Gen. Tech. Rep. 

SE-54. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station.

20 p.

Waldrop, T.A; Van Lear, D.H.; Lloyd, F.T.; Harms, W.R. 

1987. Long-term studies of prescribed burning in

loblolly pine forests of the Southeastern Coastal Plain.

Gen. Tech. Rep. SE-45. Asheville, NC: U.S. Department

of Agriculture, Forest Service, Southeastern Forest

Experiment Station. 23 p.

Yaussy, D.A.; Sutherland, E.K. 1994. Fire history in the 

Ohio River Valley and its relation to climate. In: Fire,

meteorology, and the landscape: proceedings of the 12th

conference on fire and meteorology. Bethesda, MD:

Society of American Foresters: 777-786.

321
An overstory retention harvest on the Washington State Capitol Forest. Photo by Tom Iraci
CLOSING PERSPECTIVES
Photo by Tom Iraci
1 Deputy Forest Supervisor, Gifford Pinchot National Forest, 106001 NE 51st Circle, Vancouver, WA 98682, USA. Email: lburditt@fs.fed.us

2 Collins, Sally. 2004. Environmental services: making conservation work. Speech at Outdoor Writers Association of America. June 22. Spokane, WA.

3 Some long-term study areas are incorporated into Land and Resource Management Plans; for example, the Miller Creek Demonstration Forest on the 

Flathead National Forest in Montana and the Long-Term Ecosystem Productivity Sites on the Willamette and Siskiyou National Forests in Oregon.

Balancing Ecosystem Values Proceedings, Closing Perspectives

Balancing Ecosystem Values: 

A Manager’s Perspective

Lynn Burditt1

Thank you for the opportunity to be with you this week.

My remarks will be in three segments: national, regional,

and local priorities; workshop observations; and some takehome messages.

PRIORITIES

As an agency, the Forest Service has a focus on four

major threats facing the Nation’s forests2— fire and fuels,

invasive species, loss of open space, and unmanaged outdoor recreation. Within the Pacific Northwest Region, we

have focused priorities that improve our responsiveness to

these four threats. Chief Dale Bosworth, at the 2004

Ecological Society of America meeting, referred to the “era

of ecological restoration and recreation.” The Forest

Service, and we as scientists and managers, must take a

long-term view. We must ask ourselves to balance our studies such that we not only improve insights for current managers but also design studies that will answer the needs of

the next decades, questions not fully understood or articulated today.

WORKSHOP OBSERVATIONS

Innovative experiments for sustainable forestry generate key insights for the future. This workshop compiles a

diverse potential from which to draw knowledge. The range

of posters, presentations, and field experiences include an

impressive diversity of geography, sponsorship, study type

(retrospective, model, field based), as well as spatial and

temporal complexity. Participants demonstrate a shared

understanding of the essential need to communicate effectively with a variety of public, the importance of rapid trans325

lation and transfer of information, and the power of field

experiences and visual tools to convey understanding. 

Critical elements for continued success include strong

partnerships, descriptive language, and effective integration.

Science-Manager Partnerships

Landscape-scale studies and field-based experiments

require a strong relationship among managers and scientists. It is imperative that participants value the expertise

each brings to any partnership. Landscape studies entail a

long-term commitment of a land base for the purpose of

generating information. These studies generally require a

landscape size that exceeds an “experimental forest” or a

“research natural area.” Management designations that

reflect the purposes of the study can ensure succeeding

managers are aware of the informational values being generated. This facilitates ongoing management commitment

to long-term, landscape scale studies (e.g., Miller Creek in

Montana and the long-term ecosystem productivity sites in

the Pacific Northwest3). 

Scientists and managers who work at the interface have

a shared interest in the information that is developed; however, there may be different expectations, timing needs, and

reward systems. Study design and implementation require

a willingness to work collaboratively on study questions,

meet administrative requirements, complete the appropriate

scale of environmental analysis, incorporate appropriate

pretreatment data collection, and facilitate grant proposals

and funding needs. 
Large-scale studies and long-term research face challenges similar to those many counties face: voters may be

willing to fund the capital construction of a detention or

treatment facility; however, they expect the governmental

entity to fund ongoing operations without new taxes. Over

time, we have implemented several landscape-scale studies.

We must be vigilant about the investments needed. Dedicated

follow-through is essential for scientists and managers to

maintain credibility with public. Vegetative manipulation

implemented for large-scale studies generally includes a

need for the activity to generate information. Whether

focused on applied research or adaptive management, completion of data collection, analysis, and information synthesis is imperative.

Labguage: How We Convey Meaning?

Silvicultural system language has a strong foundation

and conveys particular images. For example the terms “precommercial” and “commercial thinning” communicate an

economic objective. Although this is a useful element, the

terms may not adequately describe the management objectives. In an area where late-successional habitat conditions

are the focus, the primary emphasis is to create specific

habitat conditions. Terminology that effectively communicates this objective may not reflect the economic aspect.

The workshop dialog regarding the necessity for new terminology and whether the descriptors we use need to reflect

the mix of ecosystem values and objectives should continue.

Models

The use of simulation models and computer capability

has expanded our capacity to analyze large amounts of

information. The resultant plethora of models generates

several concerns: assessing which model a manager should

use for analysis, unwillingness to give up a model, a perception that each scientist has to generate his or her own

model (associated with the reward system), and management

(in)ability to collect and maintain data needed to facilitate

model use. These models generate graphic and pictorial

displays that are a wonderful communication tool. We need

to highlight their value for understanding and comprehension while ensuring people do not lose touch with the real

world (and why we all care about the land) as a tradeoff. 

Science-Based Information or Opinion?

We live in a world of change. During the 1980s, the

Forest Service was beginning to develop concepts of “legacy,”

whereas today it is common to hear, “We have learned that

what we leave on the land is more important than what we

take away.” We have transitioned our management from a

focus on outputs to a clear emphasis on outcomes. 

Whether a scientist intends it, the potential exists for the

individual to be seen as or used as a guru (spiritual guide

or teacher). When this occurs, some parties may view the

information as prescriptive rather than providing a basis 

to inform management decisions. One example relates to

insights Andy Carey shared regarding active intentional

management. A group of proponents has formed who feel

the only viable thinning prescription is variable density –

no matter what the land management objective, the geographic setting, the landscape context, the mix of vegetation

conditions, or the economic implications. These proponents

see the concept as a prescriptive approach that should be

applied in all settings. While we continue to develop an

understanding of public values, we must ensure we use

science-based information appropriately.

INTRGRATION AND WHERE 

WE NEED TO FOCUS

It is imperative that we consider the kinds of information

we will need 10 or 20 or 30 years from now. How can we

design and implement the integrated research questions that

will inform those needs? We must improve our capacity to

integrate efforts. The concepts of adaptive management and

research-management partnerships are articulated on many

fronts. To a large extent, current success and energy arises

from the individuals at the local level who have a shared

sense of dedication to the outcome. Within our federal agencies, we must continue to search for an enhanced institutional model if we truly want to increase our capacity for

adaptive management. 

Landscape-scale studies require large investments of

energy and resources. We must assess the lessons we are

generating and examine our commitment to follow through

for long-term information generation. This workshop focused

on innovative experiments for sustainable forestry helps

identify the proliferation of field studies that exist. The

studies discussed here represent major investments. To best

facilitate outcomes from these investments, perhaps we need

to create a vehicle to place these studies into context, synthesize key findings, provide integrative lessons, enhance

collaboration, and provide advice on which studies have

long-term merit. 

The dedication and commitment you have each made 

to generate new information for society is impressive. I

appreciate the opportunity to visit with you today and look

forward to an ongoing conversation.

326
1 Professor, College of Forest Resources, University of Washington, Seattle, WA 98195. USA. Email: edford@u.washington.edu

Balancing Ecosystem Values Proceedings, Closing Perspectives

Where Can We Go From Here? 

E. David Ford1

INTRODUCTION

First I wish to thank the meeting organizers for developing such an excellent and timely program of papers, which

combined with the field tours, has enabled us to analyze

many important issues facing the development of silvicultural and management approaches to multipurpose use forestry. I also thank the organizers for inviting me to provide

remarks to summarize the meeting and make a synthesis.

Of course this is too large a task for one person—and I am

still wondering why I agreed to attempt it! So what I offer

are some comments about specific issues that arose during

the meeting and a description of why an effort to synthesize our current knowledge is necessary, and how I think 

it might proceed.

SPECIFIC ISSUES

The value of experiments established over the last decade

has been that treatments have been replicated, and that

contrasting manipulations have been applied. For example,

DEMO contrasts quantity and pattern of removal in a factorial. Nevertheless, having been involved in the planning

process for DEMO, I am relieved that some response variables clearly show treatment effects when analyzed using

ANOVA (see Maguire et al. 2005). I am relieved because it

was apparent at the start of the work, given the distribution

of the replicates across considerable differences in landscape, that the assumption of homogeneity of variance

required for ANOVA was not likely to hold. For detecting

that there are differences between treatments, textbooks

reassure that ANOVA is robust—and so it seems to be 

in this case. 

However, we want to know not just that there are differences between treatments but what it is about the treatments

327

that produce differences in response. This more detailed

analysis is proving complex (see Maguire et al. 2005),

and it seems likely we will have to take a many-sided

approach in examining for relationships between structure of the communities created and the response of

organisms and physical and chemical properties. In particular, responses are likely to vary within treatment replicates

and to change over time—in practice the treatments have

created a set of different systems. In this case we can use

various biometric techniques, e.g., longitudinal analysis

(Diggle et al. 1994), and use what we have so far considered to be replicates as repetitions of stochastic processes,

and be very glad that we have these repetitions! So, although

the experiment was originally established as synchronic,

i.e., treatments compared at the same time because measurements were made before and after treatments were applied,

we also have possibilities for analysis as a diachronic

experiment, i.e., before and after. 

Given the time and expense concerned in collecting the

data, and the importance of the results for the development

of silvicultural techniques, it would be a terrible waste if

modern biometric techniques were not used. This is likely

to involve a detailed collaboration between scientists and

biometricians, particularly those interested in stochastic

processes. I strongly urge that analysis be followed through

to the formation of statistical models wherever possible, and

that this should be done before planning new experiments

or extending measurements in the present series. For variables where there are responses to the treatments, we need

to move on to analyze the causal processes involved. For

variables where there are no responses, or responses that

are unclear, it is import to reconsider whether the correct

measurements are being made rather than simply continuing an established protocol.
During the meeting there were a number of interesting

papers from scientists working in other parts of the world,

particularly the tropics and in the hardwood zones of central

and eastern North American. A common thread in this work,

either explicitly stated or implicit, was to consider silvicultural treatments as creating gaps and to use “gap theory” as

a theoretical foundation for the work (e.g., Canham and

Marks 1985, Runkle 1985). A note of caution for scientists

working in the tall conifer forests in western North America—

it is not clear what role canopy gaps play in the regeneration of these forests (Canham 1989), nor how and when

they come to form (Franklin et al. 2002). The initial regeneration of shade tolerant species does not require gaps and

may actually be inhibited by them if ground vegetation

develops. 

SYNTHESIS

At the meeting, both in the talks and on the field trips,

we have seen two types of experiments that ask different

questions. Experiments into silvicultural design ask, “Can

we use a silvicultural system other than clear felling to

obtain a timber yield and yet satisfy a requirement for nontimber objectives, particularly public perception?” Experiments of scientific analysis ask, “What are the ecological

consequences of removing timber in different amounts and

different spatial arrangements?” The difference in the types

of experiment is frequently apparent in the types of treatment applied. It is also apparent in the response variables

measured. I have a plea to make: Can the type and rates of

growth of natural regeneration and planted stock be measured in both types of experiment? Not only could this be an

important way to relate these different types of experiment,

but these regeneration parameters are essential for reaching

a goal of sustainability, and they will determine the ecological pathway followed after manipulations. Applying silvicultural treatments without measuring the effects and fate

of regeneration means that understanding these treatments

is postponed too long into the future. Applying treatments

to gain an ecological understanding, but restricting measurement to just the supposed response variables of interest

reduces the possibility of developing a causal theory and

reduces the utility of these results for silvicultural purposes.

I stress the need for developing a causal theory. By this

I mean a theory for the effect of timber operations on biological and ecological processes and the growth of timber

itself. The alternative to a causal theory is one based on

repeated empirical investigations. We do not have time to

develop an empirically based theory where we apply treatments and sit back and wait for results. Furthermore, experience in forestry suggests that variation in forest type and

structure can affect the results of experiments even when

we think we are experimenting within the same forest type.

A causal theory for this purpose would define accepted

information and the concepts used; it would also define

variation in treatment—response according to conditions.

Causal theories also contain questions and we can expect

them to change as knowledge improves (Ford 2000, Chapter

11). The definition of a causal theory would be more than

typically is found in an academic review, in particular, it

would define uncertainty. I suggest that the development 

of such a theory for the conifer forest of the Pacific Coastal

region should be an international task, very suitable for

IUFRO. After all IUFRO was founded in response to similar requirements in European forestry. One reason for an

explicit definition of a causal theory is to ensure the use of

appropriate models. Unfortunately we all too frequently see

the requirement for a theory relapse to some model that is

available and/or in current use.

IN CONCLUSION

In response to the question,“Where can we go from

here?” I offer three suggestions:

1. Specify the theory of regeneration in conifer forests in

relation to potential manipulations and their effects on

timber and nontimber objectives. This is a task of synthesis, and I suggest it would best be conducted as an

international exercise. And, although scientists are 

clearly essential for specifying known and likely interactions between processes, the theory should have a

clearly specified management purpose.

2. Postpone additional large-scale initiatives until a 

theory is specified and focus on analysis of results 

from current experiments. Analysis of results from

recent experiments is essential for developing a theory,

this analysis is not complete and has not been integrated with existing information and theories on forest

development, habitat creation, and management.

3. Anticipate investment in Living Forest Laboratories. 

The various experiments established in this forest type

are likely to be important in the future because treatments have been repeated. At least some of these 

experiments should be carefully managed and deciding

which ones should depend upon the results of my first

suggestion.

328
REFERENCES

Canham, C.D. 1989. Different responses to gaps among 

shade-tolerant tree species. Ecology. 70: 548-550. 

Canham, C. D.; Marks, P.L. 1985. The response of woody 

plants to disturbance: patterns of establishment and

growth. In: Pickett. S.T.A.; White, P., eds. The ecology

of natural disturbance and patch dynamics. San Diego,

CA: Academic Press Inc.: 197-216.

Diggle, P.J.; Liang, K.Y.; Zeger, S.L. 1994. Analysis of 

longitudinal data. Oxford, UK: Clarendon Press.

Ford, E.D. 2000. Scientific Method for Ecological 

Research. Cambridge, UK: Cambridge University Press. 

Franklin J.F.; Spies T.A.; Van Pelt, R.; Carey, A.B.; 

Thornburgh, D.A.; Berg, D.R.; Lindenmayer, D.B.;

Harmon, M.E.; Keeton, W.S.; Shaw, D.C.; Bible K.;

Chen, J.Q. 2002. Disturbances and structural development of natural forest ecosystems with silvicultural

implications, using Douglas-fir forests as an example.

Forest Ecology and Management. 155(1-3): 399-423. 

Maguire, D.; Canavan, S.; Halpern, C.B.; Aubry, K.B. 2005.

Fate of taxa after variable-retention harvesting in

Douglas-fir forests of the northwestern United States.

In. Peterson, C.E.; Maugire, D., eds. Balancing ecosystem values: innovative experiments for sustainable

forestry, proceedings. Gen. Tech. Rep. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 

Runkle, J.R. 1985. Disturbance regimes in temperate forests.

In: Pickett, S.T.A.; White, P., eds. The ecology of natural disturbance and patch dynamics. San Diego, CA:

Academic Press Inc. 17-33.

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331

The Oregon Department of Forestry claims Oregon

forests grow 10 billion board feet (bf) annually; 4 billion 

bf are cut annually. How long can we continue to store this

extra fiber? How long should this situation continue, especially in our dry forests where extra carbon is recycled

mostly by fire rather than by decomposition?

The biggest forcasting problem, as I see it, on federal

land is that the federal government (USDA Forest Service

and USDI Bureau of Land Management) is not accurately

predicting the consequences of forest succession without

restoration management and the consequences of succession with different types of management intervention. If

current (deficient) simulations are not viewed as credible

among federal, state, and industry biologists, they will have

little use. I applaud your efforts to create the data and models for improved simulations.

While I was reading your abstracts, I remembered a 

discussion Dr. Arnie Skaugset and I had about the stream

surveys we did as an industry. He showed the Oregon

Forest Industry Council that industry riparian areas were

not statistically different from state or federal areas. Then

he told me that natural variation is so large that it will be

very expensive to quantify the footprint of management on

the landscape. I see each of you struggling with this same

sampling problem as well.

In my opinion, experience over the past 10 to 15 years

in dry (mostly federal) forests shows the following:

Forest succession without restoration produces fire prone

landscapes (Condition Class III). In many cases, this places

watersheds as well as wildlife habitat and species at risk. 

Managed disturbance (forest restoration) can be more

effective than natural disturbance (uncharacteristic wildfire) in maintaining watershed and wildlife values.

There are many locations where the long-term benefits

to watersheds and wildlife values of forest restoration outweigh the short-term risks of such restoration. It’s apparent

to me that in most cases, in dry, fire-prone forests “no action

(no restoration management) is not good for wildlife.” I

was not surprised to see that the review team for the status

of the northern spotted owl (Strix occidentalis caurina)

identified uncharacteristic wildfire as the major cause of

habitat loss for the northern spotted owl from 1994 to 2004.

I’ll feel a lot better about this when there is broader understanding and acceptance of this reality, especially in the

biological community. Until this happens, there will likely

be very limited economic, social and biological benefits

from our “at risk” fire-prone forests with little restoration

being accomplished at a landscape scale.

So why would biologists want to participate in this discussion? What follows are some things I have observed in

southern Oregon.

Losses on the Biscuit fire:

• Marbled murrelet (Brachyramphus marmoratus) critical

habitat, 96 million acres, 65 percent (heavy/high mortality)

• Northern spotted owl critical habitat, 69 million acres,

63 percent (heavy/high mortality)

• Coho salmon (Oncorhynchus kisutch) watersheds, 

338 million acres, 65 percent (heavy/high mortality)

• Late-successional reserve, 160 million acres, 68 percent

(heavy/high mortality)

Balancing Ecosystem Values Proceedings, Closing Perspectives

Summary of “Realities in Timber Management” 

Discussion at 2004 IUFRO Workshop

Russ McKinley1

1 Boise Cascade, P.O. Box 100, Medford, OR 97501, USA. Email: russmckinley@boisebuilding.com
Seventy-seven percent of Oregon’s forests (24.5 million

acres) are in Condition Class II or III. 

Recent review of the northern spotted owl on dry site

Douglas-fir showed “uncharacteristic wildfire” to be the

single largest threat.

Without restoration, Class II becomes Class III. If private land cannot be used for forestry, it will be developed

for home sites. If the land was appropriate for agriculture

or industry, it is probably already in use. This, in my experience, is not good for wildlife.

Forest certification forces landowners to consider wildlife and the effect of the management plan on landscape

biodiversity. Our biologists helped us develop our plan but

really struggle to quantify the good or negative aspects of

the plan. We pass our audits and feel good about our plans

but struggle to quantify value. I keep asking, and the biologists want to know also.

Given the mix of government, large owners, and small

owners, we may be providing the landscape we need. We

can’t quantify what we do; we as a society can’t agree on

biodiversity objectives and for some groups; this confusion

helps them generate revenue. I truly believe there is no 

better private use of forestland that has to pay taxes than

forestry. The research you are doing will over time help us

improve through the Sustainable Forest Certification

process. 

I spent parts of 2 days reviewing your conference

abstracts. As scientists, I understand that you need to produce peer-reviewed replicable research. As a result of my

review, here are some observations for your consideration.

Much of the results were stand-level results. This makes

sense to achieve proper statistical precision. The work you

are doing is absolutely critical to preserving a broad range

of habitat. I suggest it is time to combine many of these

models so they can be used for landscape assessment. We

recently completed a landscape assessment for northern

spotted owls in southwest Oregon. It was a very large effort,

but it did produce results that interested managers and biologists. We have a new appreciation for the importance of

forest restoration management in protecting the habitat of

northern spotted owl over many decades. Natural variation

made this work much more difficult than anticipated. Getting

clean data sets on 800,000 acres took much more time than

anticipated. We found a “light touch on the land” was worse

than no action, and bolder approaches had much better

results at controlling uncharacteristic wildfire. This was

better in the long run for northern spotted owls. The strategic problem of where you can apply treatments and then

the strategic problem of where you should put the treatments are challenges we will struggle with for at least the

rest of my career. Quantifying the “footprint of any kind of

management” on the landscape is a very stiff challenge. 

When I reviewed my thoughts with Steve Mealey, Boise’s

manager of ecology, he pointed out that at the November

2003 Risk Conference in Portland, Mark Finney reported

that his modeling work with FARSITE indicates that less

than or equal to 25 percent of a landscape can be treated to

effectively reduce fire risks across the entire landscape, as

long as the treatments are strategically placed. If such treatments are not strategically placed, as much as 50 percent of

the landscape must be treated to create resiliency. Strategic

placement of treatments for effectiveness in reducing

resiliency requires landscape-level assessments and planning. This strongly supports concerns about the need to plan

and assess ecosystem conditions at the landscape scale.

Increasingly, professional cultures control how our

work is used in decisionmaking. Learning to work within

those cultures in a collaborative way makes the difference

in whether the good work you produce will ever get used.

In our case, if the biologists do not loudly acknowledge

that wildlife habitat is at risk from lack of restoration management, I doubt your work will have much value.

Until biologists and interdisciplinary teams loudly ask

for designed and carefully executed restoration management for “at risk” forests, I predict there will be little economic and related social value generated from the harvest

of timber on federal lands.

Large fires originating on Class II and III forests will

continue to damage our company timberlands. These forest,

vulnerable to lightening, are growing in size and number.

Working collaboratively with biologists could introduce

controlled restoration management and limit the size and

damage of these wildfires. 

We need you and the biologists to be successful. I worry

that it may take a long time. The mill capacity to support

federal land management programs is mostly gone. The

economic pressure to produce an annual cut is almost gone.

Predictable succession patterns without forest restoration

management will create forests that will burn with uncharacteristic intensity and waste useable wood and damage

habitat.

332
The Healthy Forest Restoration Act says to me that

accurate simulation analysis of forest succession with different types of management intervention is both desired

and required for successful forest ecosystem management

and timber sales on federal lands. The door is open. Make

your work count!

When your collaborative work with biologists and interdisciplinary teams is successful, management strategies will

develop that could create economic opportunity. These opportunities can be pursued and social benefits will result. If this

challenge is not met, the rest of the world will gladly supply our wood products. No shortages will occur for long at

the home improvement centers, just lost opportunities to

provide for our own needs sustainably.

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Good morning. The two areas I will address are my

general impressions of the conference and the relevance of

the work I have seen with regard to Washington Department

of Natural Resources’ (DNR) needs. 

DNR has two major roles: natural resources protector

and land manager. As resource protector, DNR provides

regulation of forest practices and fire protection for state

and private forested lands in Washington, regulates mining

reclamation, and assists rural and urban private landowners

accomplish healthy ecosystems on their small forests or

urban properties.

As land manager, DNR is steward of 2.4 million acres

of the state’s aquatic lands – bedlands, tidelands, many

beaches, and navigable lakes and rivers. In addition, DNR

is a manager of 2.1 million acres of forestland and 800,000

acres of farm and grazing lands, and additional commercial

properties. These are state trust lands, managed in trust to

provide revenue for multiple public benefits including funding construction of public schools statewide and universities

and funding services in many counties. The income earned

from these lands is paid directly to the specific beneficiaries

and amount to about $150 million a year. My comments

today will be made from the perspective of a land manager

of these proprietary holdings.

First, my general impressions: 

I heard three major themes at the conference and will

illustrate those themes with quotes from the various speakers or participants. 

The first theme relates to the relative dearth of information on anything other than regeneration harvest, particularly

in the Pacific Northwest region of the United States. This is

an important issue because many forestry organizations are

beginning to experiment with new harvest methods such as

variable retention harvest and biodiversity pathways, yet

there is little experimental evidence to guide the silviculture.

Jerry Franklin described the current status of this issue in

his introductory remarks. He said, “We have framed two

end points...Clear-cut management and no management,

but nothing in between. But now we are starting to work

there.” However, “...ecological science [with regard to this

area in between] is a series of theoretical constructs that are

untested... We need some data on these systems...”

I agree with Franklin’s comments and think he would

add that data are only one part of the problem. In many

cases we lack unifying theories, or constructs, to guide our

actions. One example is the arena of biodiversity. As Steve

Zack said, “Biodiversity is bean counting”... but not

always... “It is inappropriate to confuse the conservation

interest in maximizing biodiversity with efforts like those

in the restoration of ponderosa pine where the emphasis is

in restructuring the habitat and reinstalling fire. The effect

might be local reduction in biodiversity (“species richness”)

as the habitat is simplified with treatments, but, if we are

truly concerned with the habitat and processes, then prior

higher richness was an artifact of fire suppression, and our

restored ponderosa pine forests have the ‘relevant’ richness.”

This comment by Zack illustrates the complexity of such

issues as ecosystem restoration and preservation of biodiversity.

With all this uncertainty, it is nice to know that there 

is some certainty in life. Dan Luoma summed up his entire

presentation in the simple, certain, and bumper-stickerready comment – “No fungi, no forests.”

The second theme relates to the need for long-term

research. It often seems that just when a research project

335

Balancing Ecosystem Values Proceedings, Closing Perspectives

A Public Land Manager’s Perspective: 

The Need for Innovative Experiments for Sustainable Forestry

Gretchen Nicholas1

1 Washington State Department of Natural Resources, PO Box 47016, Olympia, WA 98504, USA. Email: gretchen.nicholas@wadnr.gov
starts gathering the information we need over a long enough

time frame to be valuable, the funding is gone. Many times

at this conference researchers have mentioned that funding

sources often seem fickle and driven by political interests. 

I overheard Klaus Von Gadow making the remark, “All

important decisions are made in 10 minutes.” Although that

humorous comment is not entirely true, it is true that many

decisions on funding are made by managers like me, who

have a great number of priorities to balance and goals to

achieve. We are usually looking for projects that meet our

long- or short-term goals. This search for relevance brings

me to the third theme.

The third theme I heard is that partnership between

managers and scientists is needed to achieve relevance.

That type of partnership is demonstrated by research such

as the Blue Ridge study (silvicultural options for younggrowth Douglas-fir forests) in DNR’s Capitol Forest near

Olympia This study examines biotic responses to alternative silvicultural regimes such as group selection, patch

cuts, thinning and regeneration harvest with leave trees.

The presenter for that study, Dave Marshall, emphasized

that this study originated at the request of field personnel. 

I offer some advice for the scientist embarking on a partnership with managers in research. As Lisa Ganio emphasized, it is important to develop a focused understanding of

the question that must be answered before a study is designed.

Once the data are being analyzed, it is too late. Lisa also

pointed out that the broader the scope of inference of a study,

the more valuable the research results will be. 

Producing results when the results are needed also is

important to maintaining funding. As Mike McClellan accurately observed, “We need to produce something in the short

term as well as the long term. Use retrospective studies to

provide interim guidance, if necessary.” I would add, as

suggested by several speakers, modeling with adequately

validated models can also provide near-term information.

A good example of the combined use of modeling with

retrospective studies as a starting point, followed by the

installation of long term studies, can be found with the

Biodiversity pathways approach developed by Andrew

Carey and his colleagues at the U.S. Forest Service. The

concept of “biodiversity pathways” is based on the four

possible types of major studies: (1) literature review and

synthesis to produce theory; (2) retrospective (or comparative/cross-sectional) studies to provide quantitative guidance

for treatments; (3) prospective (or experimental studies like

the Forest Ecosystem study in its 13th year and the Olympic

Habitat Development Study, with plots up to their 7th year

post-treatment) to test hypotheses under the new theory;

and (4) simulation studies (the Washington Forest Landscape

Management Project) to integrate various models and compare alternative pathways with respect to social, economic,

and ecological results); DNR just completed some of its

own in-house simulations studies in its Sustainable Harvest

analysis. 

The second major topic I will discuss is the relevance 

of the research presented at this workshop to the DNR. The

DNR recently completed a final Environmental Impact

Statement (EIS) for management of 1.4 million acres of

forested state trust lands west of the Cascade Range. The

Board of Natural Resources, which represents the beneficiaries and makes major policy decisions regarding DNRmanaged lands, decided in September 2004 to implement

the preferred alternative. The preferred alternative specifies

that in areas targeted for habitat development, a large proportion of the annual acreage planned for harvest will be

devoted to a biodiversity pathways approach. This will

amount to approximately 20 to 30 percent of the 15,000 to

20,000-acre annual harvest. Results will be monitored to

assure that the dual objectives of income to the trusts and

habitat creation are being met. But long-term success

depends on long-term information, and this new direction

creates a need for increased information in the following

areas:

• Progression of forest structural stages and modeling of

stand growth in response to biodiversity management

• Growth of regeneration in patch and group selection

scenarios 

• Sampling methods for multiple age stands

This information will help determine whether DNR is actually creating the stand features it wishes to, and ultimately

through monitoring, will determine whether the result is

improved habitat. 

Forest inventory is expensive, and the DNR has invested

extensively in good inventory samples and GIS information.

Yet future necessary information will be more extensive than

our current techniques can address. We must find efficient

ways to meet future need for new types of data without

increasing information collection costs. One arena that shows

promise is the laser imaging technology called LIDAR

336
(light detection and ranging).2 There are many information 

needs that can be filled by LIDAR. For example, measurements of vegetation structure can be used to infer stand

development stages, Steve Reutebuch discussed on-going

research that he and colleagues are pursuing that would provide tree-, stand-, and landscape-level structure measurements that are geospatially referenced and compatible with

existing GIS stand information. If successful it could result

in an effective means to monitor forest structural changes

over time in response to planned treatments.

Research can be made more relevant to operations if

researchers develop thresholds whenever possible. For

example Gordon Bradley’s work on visual impacts of various types of silvicultural activities has been extremely useful to the DNR in determining types of harvest patterns to

use in visually sensitive areas. We know from his studies

that scattered leave trees are visually pleasing to most of

the individuals surveyed. The minimum number of leave

trees per acre required to create the positive viewer reaction would be useful “threshold” information to help in

guideline development. With better data on the incremental

impacts of increased levels of overstory on various understory

species, we could frame appropriate leave tree targets in

visually sensitive areas. The collaborative (Washington

Department of Natural Resources/Pacific Northwest

Research Station) Overstory Density Study at Capitol

Forest will provide such needed information. 

Another area in which DNR needs more information

about thresholds relates to public concerns about cumulative

impacts within a landscape and how that affects biodiversity.

The DNR has substantially addressed this issue through its

multi-species habitat conservation plan. In addition the DNR

has adopted a modified variable retention strategy and has

recently completed a final EIS that calls for a substantial

implementation of the Biodiversity pathways approach

developed by Andrew Carey and his colleagues. As I previously mentioned, these strategies represent the best efforts

of scientists to use various research methods to develop

answers about how to conduct harvest in forests and still

preserve biodiversity. More information is needed about

the impacts of various levels of deviation from historic 

levels of disturbance, which would allow for a better

understanding of landscape and stand level targets. Bob

Seymour took a step in that direction with his work on

indexing activity to historic frequency and extent of disturbance. Equally promising is some of Fred Bunnell’s work

that tackles the biodiversity issue from a strategic level by

setting criteria for landscape level activities. I look forward

to reviewing his work more closely and to seeing what

information he uses to quantify his targets.

In conclusion, there are tremendous operational research

opportunities on DNR-managed state trust lands. As the

Capitol Forest tour demonstrated, we are able to complete

the harvest of experimental designs expeditiously, we have

excellent resource information and tracking systems, and

we are experimenting with innovative methods of forest

management. We have had very successful collaboration

with the Pacific Northwest Research Station thus far, and

look forward to strengthening that relationship and others

that can move us all forward in the management of healthy,

diverse and productive forestlands.

337

2 LIDAR (LIght Detection And Ranging) uses the same principle as RADAR. The LIDAR instrument transmits light out to a target. The transmitted

light interacts with and is changed by the target. Some of this light is reflected or scattered back to the instrument where it is analyzed. The change in the

properties of the light enables some property of the target to be determined. The time for the light to travel out to the target and back to the LIDAR is used

to determine the range to the target. (http://www.ghcc.msfc.nasa.gov/sparcle/sparcle_tutorial.html)
Public perceptions of silvicultural options for

harvesting young-growth forests are presented

by Gordon Bradley (University of Washington)

during field tours of the Capitol Forest Blue

Ridge study. Photo by Robert Harrison

Photo by Charley Peterson

continue
POSTER ABSTRACTS
Photo by Tom Iraci
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1 USFS Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA

2 USFS Cascade Center for Ecosystem Management, 57600 McKenzie Highway, McKenzie Bridge, OR 97413, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

The H.J. Andrews Uneven-Aged Management Project: 

Alternative Silvicultural Approaches to Stand Conversion 

Paul Anderson1 and Jim Mayo2

The H.J. Andrews Uneven-Even Aged Management Project was undertaken to explore ecological and economical

compatibility among silvicultural options for converting 40- to 50-year-old Douglas-fir plantations (Pseudotsuga menziesii

(Mirb.) Franco) in western Oregon to mixed-species and uneven-aged condition. Three silvicultural prescriptions for conversion are being evaluated: (1) individual tree selection (light thin), (2) group selection (groups cuts, light thin of matrix

and mixed species planting of gaps), and (3) heavy thin with mixed-species underplanting. In all three treatments, timing of

subsequent entries will be based on stands achieving specified thresholds of relative density. The three treatments, as well as

an untreated-control, were applied to stands 10-ha or larger and replicated in four blocks. Initial harvest entries occurred in

1999 with vegetation conditions being measured in 1997-98 (pretreatment) and in 2001 and 2003. This poster presentation

summarizes herbaceous and shrub vegetation responses through 3 years following initial harvest entries. Analyses will

describe dynamics of species richness, community composition and relative abundance in relationship to residual overstory

cover. Observed vegetation responses will be discussed in the context of habitat quality and additional opportunities for

small-mammal, arthropod, insect, and amphibian research. 
1 Weyerhaeuser, BC Coastal Timberlands, 65 Front St., Nanaimo, BC V9R 5H9, Canada

2 Symmetree Consulting Group, 4654 Keith Rd., West Vancouver, BC V7W 2M6, Canada

3 Symmetree Consulting Group, 6301 Rodolph Rd., Victoria, BC V8Z 5V9, Canada

Balancing Ecosystem Values Proceedings, Poster Abstracts

Variable-Retention Implementation Monitoring 

William J. Beese,1 Ken Zielke,2 and Bryce Bancroft3

Weyerhaeuser’s British Columbia Coastal Timberlands has adopted the variable retention approach to harvesting and 

silviculture for all of the company’s public and private forest land. The phase-in of variable retention was accomplished

over a 5-year period from 1999 through 2003. As part of our adaptive management program, we monitored operational

implementation to see if our goals and standards were being met. Symmetree Consulting Group completed evaluations on

248 variable retention cutblocks over this period representing over 6 000 ha to monitor performance and identify areas for

improvement. This represented a random sample of over 15 percent of all variable-retention harvesting. Evaluations included

both the prescription and the results on the ground. This paper presents a summary of the methods and findings of this monitoring program. Statistics were compiled on the amount and type of retention, size of groups, type of stand attributes and

ecological features retained, protection of small streams and riparian areas and the visual aesthetics of the block design. 

An overall rating of each block was also given based on the degree to which it met the goals for variable retention. 

342
343

1 Department of Forest Science, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Characterizing Vegetation Response to Variable Density 

Thinnings in Young Douglas-fir Forest of Western Oregon 

Shanti Berryman,1 Bob Fahey,1 and Klaus Puettmann1

The Density Management Study was designed to investigate whether thinning to various densities within a stand can

accelerate development of late-successional characteristics in young, managed Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco) forests (40 to 70 years) while producing wood for the regional economy. Seven initial thinning study sites are

located in the Coast Range and Cascade Foothills of western Oregon. The four treatments implemented at each site include

an uncut control and units containing one of three levels of residual tree density (high, moderate, and variable density) with

circular leave islands and patch cuts of three sizes (0.25, 0.5 and 1.0 acre). The patch cuts and leave islands represent a relatively small proportion of the overall treatment at each site (about 10 percent of the area is patch cuts and 10 percent is leave

islands). The thinning treatments were designed to increase overall stand heterogeneity by thinning from below and by

retaining hardwood tree species and conifers that were under-represented in the overstory canopy. We are investigating the

response of overstory and understory vegetation to the harvest treatments. Preliminary results summarize differences in

overstory and understory vegetation composition and structure in relation to the thinning treatments 1 and 5 years following

harvest. In addition, we evaluate the relative influence of the patch cuts and leave islands on the understory vegetation

response within the treatments.
1 Departement de biologie, Universite de Sherbrooke, 2500, boul. De l‘Universite, Sherbrooke, QC J1K 2R1, Canada

Balancing Ecosystem Values Proceedings, Poster Abstracts

Black Spruce Regeneration in the Presence of 

Kalmia Angustifolia L.: Interactions with Irradiance and Nutrients 

Felix Boulanger,1 Bill Shipley,1 and Robert Bradley1

Conifer regeneration failure in the presence of Kalmia angustifolia L. has been attributed to allelopathy, nutrient cycling,

and root competition. This phenomenon challenges the sustainability of present harvesting practices in many boreal forests

because reforestation of ericaceous-dominated sites in eastern Canada has been problematic. So far, few studies have focused

on available light and soil fertility as possible factors controlling the competitive ability of Kalmia. We, therefore, monitored

the growth of 120 spruce seedlings assigned to a split-plot field experiment in the southern boreal forest of Québec. Experimental treatments consisted of a factorial array three main-plot light levels (100-percent, 40-percent, 16-percent incident

light), two subplot nutrient levels (unfertilized, fertilized), and two subplot competition levels (presence, absence of Kalmia).

Following two growing seasons, the growth of black spruce seedlings was significantly higher at 100 percent light with

fertilizer, than in the other treatment plots. The presence of Kalmia had no effect either alone or in interaction. Either both

poor regeneration and abundance of Kalmia are effects of infertile soil, or the previous presence of carbon on the site had

modified the soil properties and these modifications persisted after Kalmia was removed. Results are discussed in terms of

forest management, as precommercial and commercial thinning are commonly applied silvicultural systems in the boreal

forest of Québec. We suggest how a better comprehension of the effects of canopy openness and fertility on the black spruceKalmia dynamics could help develop innovative management practices and preharvest decisionmaking in boreal forests.

344
345

1 Humboldt State University, Harpst St. Arcata, CA 95521, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Twenty-Five-Year Results of a Restoration 

Thinning, Redwood National Park

Andrew Chittick1 and Christopher Keyes1

INTRODUCTION

The current biological landscape of Redwood National

Park has been affected by past logging. These second-growth

forests are characterized by an extremely high density of

trees, stagnated growth and development, high fuel loads,

absence of understory vegetation, and a homogeneous vertical structure. Studies conducted throughout the Pacific

Northwest on the effects of thinning in young forests have

concluded that reducing stand densities can greatly increase

structural characteristics associated with late-seral forests

in a shortened period of time (Bailey and Tappeiner 1998,

Newton and Cole 1987). 

The Holter Ridge Thinning Study, located about 6 miles

inland from the coast in the headwaters of Lost Man Creek,

was initiated in 1978 on a 25-year old redwood Sequoia

sempervirens (D. Don.) Endl.)/Douglas-fir (Pseudotsuga

menziesii (Mirb.) Franco)/tanoak (Lithocarpus densiflorus

(Hook and Arn.) Redh.) forest. Intended as an operational

case study, the goals of this research are to observe effects

of a low thinning with varying stand densities on mortality,

growth, species composition, and structural characteristics.

Densities ranged from 150 to 550 trees per acre (tpa) in the

thinned units and from 1200 to 3200 tpa in the control at

25 years of age. Species composition varies from redwood/

Douglas-fir, to redwood/Douglas-fir/tanoak, and to exclusively redwood. Results of this research are intended to

increase the knowledge of stand development in young, mixed

redwood/Douglas-fir/tanoak forests and inform future second-growth management within Redwood National and

State Parks.

METHODS

Data taken in 1979, 1984, and 1995 showed an increase

in basal area growth and reduced mortality related to lower

stand densities. However, longer term quantitative analysis

and research into stand structure and development are lacking in this study. During the summer of 2003, remeasurements of the original data were conducted on 28, 1/10-acre

permanent plots. By using linear regression analysis, stand

densities and species compositions are compared to changes

in species composition, mortality, tree regeneration, understory vegetation, and height and crown differentiation.

Measurements of understory vegetation include estimated

cover by species and were analyzed for species richness

and Shannon-Weiner diversity index. Stand structure was

analyzed by using a modified Shannon-Weiner index in

which basal area for a plot was proportioned into three

separate indices: species, diameter class, and height class

(Staudhammer and LeMay 2001). These indices were then

averaged for a total structural index. Individual plots were

also grouped post-facto according to post-treatment densities and species composition. These groups include control

(~2000 tpa), low-density (~250 tpa), mid-density (~500

tpa), and redwood (~450 tpa). 

RESULTS AND DISCUSSION

Mortality among redwood and Douglas-fir were highly

correlated with residual stand densities, but tanoak was not

significantly related. Changes in species composition in the

control plots revealed a significant decrease in the numbers

of redwood and Douglas-fir relative to tanoak. This trend

will decrease as redwood and Douglas-fir occupy the overstory canopy with tanoak in the lower canopy. Changes in
346

species composition for all thinning treatments were minimal suggesting that thinning in dense stands can restore

and over time maintain desired species compositions.

Understory vegetation showed the greatest response due

to thinning with post-treatment stand density accounting for

87 percent of the variation seen in the cover of understory

species. Change in understory cover was dramatic with densities around 150 trees/acre showing an 80-percent increase

from 1984 to 2003 and stands over 1000 trees/acre decreasing by 60 percent. Shannon-Weiner diversity index was

calculated on the basis of percent cover in which stand

density negatively correlated to diversity accounting for 65

percent of the variation. Species richness was not correlated

to stand density and may be related more to overstory

species composition.

Sprouting response of redwood and tanoak to thinning

was compared to the number of redwood/tanoak thinned/

acre. Redwood sprouting was positively correlated to the

number of redwoods thinned but exhibited a patchy nature

due to competing shrubs and closed canopies. The number

of sprouts ranged from 0 to 3160 stems/acre while the number of redwoods cut ranged from 0 to 970 stems/acre.

Stand structure was analyzed according to post-facto

groupings. Diameter and height distributions revealed no

stratification taking place in the controls while mid-density

showed initial development into an upper canopy consisting of Douglas-fir and redwood and a lower canopy of redwood and tanoak. The low-density group showed a similar

but more pronounced stratification by species. The redwood

group developed a continuous canopy layer that was weighted

towards the upper-canopy. The construction of a structural

diversity index incorporating overstory horizontal, vertical,

and species diversity yielded a positive correlation between

stand density and structural diversity. Because the ShannonWeiner index calculates a higher diversity for more classes

and evenness, the control plots were given a higher value

due to their high uniformity. The development of multiple

strata in the lower density thinned plots led to lower values. The redwood plots showed a high diameter and height

class diversity but scored low on species diversity due to

its redwood dominance.

CONCLUSIONS

Overall, the reduction of stand densities from thinning

in dense, young stands has the ability to accelerate stand

development, mainly through bypassing the competitionexclusion stage of stand development. Characteristics associated with late-seral forests are consistently present in

thinned stands, albeit in the beginning stages. Understory

vegetation especially in the shrub and fern layer has become

reestablished whereas in the unthinned stand it is now minimal to absent. The cutting of redwood and tanoak has created a patchy mosaic of advanced regeneration. Because of

their high shade-tolerance, they may be released into future

gaps created in the overstory. The development of multiple

strata has taken place with lower densities showing a stronger

separation into separate layers. Stand measures of structural

diversity, in this case, do not represent the significant structural changes that have taken place due to thinning and cannot be relied on as a measure of desirable characteristics.

Long-term results such as those obtained here show that

in some developmental characteristics, such as understory

shrubs, the acquisition of those characteristics can take place

in a relatively short time. Other characteristics, such as gaps

or the release of advance regeneration into the mid-canopies,

will take a significant amount of time before they are attained.

Nevertheless, the development in stands with reduced densities will outpace those that remain at high-densities and

more closely approach the desired future conditions of old

forests.

REFERENCES

Bailey, J.D.; Tappeiner, J.C. 1998. Effects of thinning on 

structural development in 40- to 100-year-old Douglasfir stands in western Oregon. Forest Ecology and

Management. 108: 99-113.

Newton, M.; Cole, E.C. 1987. A sustained–yield scheme 

for old-growth Douglas-fir. Western Journal of Applied

Forestry. 2: 22-25.

Staudhammer, C.L.; LeMay, V.M. 2001. Introduction and 

evaluation of possible indices of stand structural diversity. Canadian Journal of Forest Research. 31: 1105-1115.

Veirs, S.D. 1986. Redwood second growth forest stand 

rehabilitation study, Redwood National Park: evaluation

of 1978-79 thinning experiments. Draft copy. Orick:

CA: Redwood National Park. 34 p.
347

1 Bureau of Land Management, Eugene, OR 97440, USA

2 USDA Pacific Northwest Research Station, Corvallis, OR 97331, USA. Chan is currently with Extension Sea Grant, Clackamas County Extension Service, 

Oregon City, OR 97045, USA

3 Department of Forest Science, Oregon State University, Corvallis, OR 97331, USA

4 Botany and Plant Pathology Department, Oregon State University, Corvallis, OR 97331, USA

5 Forest Resources Department, Oregon State University, Corvallis, OR 97331, USA

6 Bureau of Land Management, Salem, OR 97306, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Density Management Study: 

Developing Late-Successional Habitat

John Cissel,1 Deanna Olson,2 Sam Chan,2 Klaus Puettmann,3

Andrew Moldenke,4 John Tappeiner,5 and Charley Thompson6

The Bureau of Land Management (BLM), working in partnership with the U.S. Geological Survey, Oregon State

University, and the Pacific Northwest Research Station, initiated the Density Management Study (DMS) in 1994 to demonstrate and evaluate different approaches to managing 40- to 70-year-old, low-elevation forest stands for late-successional

forest characteristics. Study treatments were installed from 1997 to 2001 on 12 BLM sites in western Oregon. There are

seven initial thinning study sites where four stand treatments of 30 to 60 acres each were established. These treatments

combine different residual tree densities, leave islands of three sizes, patch cuts of three sizes, and an untreated control.

Alternative riparian buffer treatments were nested within the moderate density retention treatment. Buffer widths include 

(1) streamside retention, (2) variable width of approximately 50 feet, (3) one full tree height, and (4) two full tree heights.

Rethinning studies were installed in five 60- to 70-year-old stands that had been previously thinned. Each study stand was

split into two parts: one part as an untreated control, and the other part designated for rethinning. Rethinning treatments

were installed to create horizontal variability in overstory tree density, but there were no specific leave island or patch cut

objectives. Multiple studies are underway to assess the responses to these treatments. Primary components include vegetation (trees, shrubs, and herbs), aquatic vertebrates and habitats, aquatic and terrestrial arthropods, riparian microclimate and

microhabitat, and the effectiveness of leave islands as refugia for mollusks, amphibians, ground arthropods, and herbaceous

vegetation. 
1 Department of Forest Science, Oregon State University, Richardson Hall, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Predicting Understory Light Availability Based on 

Neighborhood Height Data Derived From Vertical Point Sampling 

in Mature Douglas-fir Forests in the Western Cascades

Nathan Davis1 and Douglas Maguire1

The survival and growth of understory trees is strongly influenced by light levels below the over-story canopy. An

understanding of how stand composition and structure influence light is useful when developing management prescription

to create favorable conditions for understory trees. The growth of many coniferous species increases in linear matter with

light availability. Direct measurement of light levels with instruments has proven to be expensive and time-consuming.

Models have been developed that predict light transmittance on the basis of crown or stand architecture, but they involve

the collection of a detailed set of measurements to calibrate. To be useful for prescribing foresters, a model to characterize

light should only include variables easily measured in stand examinations. Micro-site measures including density, total volume, total height and total diameter at breast height on fixed neighborhoods have proven to be strong predictors of understory light. Total summed height has been shown to be an especially good predictor because it incorporates both stand

density and influence of height on angle of incidence of radiation to the forest floor. However, collecting total height data is

often cost prohibitive. In this study, we examined if vertical point sampling is a potential alternative approach to collecting

height data while retaining the structural attributes strong predictive power. Early results suggest that height data derived

from angle sampling is statistically correlated with light availability between 20-100 percent of full sun. However, when 

the available light drops below 20 percent the performance of angle sample derived summed height data is very weak. 

348
1 School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA

2 USDA Forest Service, Southern Research Station, Prineville, LA 71360, USA

3 School of Forestry, Louisiana Tech University, LA 71272, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

An Application of Hierarchy Theory 

to Long-Term Sustainability

Thomas Dean,1 Andrew Scott,2 and Ray Newbold3

Traditionally, the effects of cultural practices on long-term productivity of commercial forests have been investigated

under the assumption that forest growth is substrate limited. Regarding regeneration, effects typically under consideration

are soil compaction and organic matter removal that either limit root growth or reduce nutrient availability in the absence of

erosion. Tree growth, however, is only weakly related to soil physical properties and nutrient availability. Furthermore, soil

structure and organic matter recover with time, in many cases, leading to the conclusion that any effects that regeneration

practices may have on forest growth are probably temporary. 

One of the difficulties in assessing the long-term effects of cultural practices on forest productivity is the lack of a good

measure of productivity. Productivity is the capacity to produce, which is difficult to measure directly. This is why many

investigators use a soils-based approach to measure productivity. 

Productivity is the outcome of a complex system, a system comprised of numerous levels of organization arranged within a hierarchy (Ahl and Allen 1996). The principal attribute of complex systems is asymmetric relationships between levels

where the behavior of lower, relatively more dynamic levels are held in check by higher, relatively slower levels. Asymmetric

relationships exist in many forms. The most easily recognized asymmetry is one where a higher level of organization places

constraints on the range of activity exhibited by a lower level of organization. Another important form of asymmetry is

where the higher level of organization buffers or filters factors influencing a lower level of organization. An example of

buffering is the influence of a mature canopy on the understory microclimate. 

Many of the constraints and buffers provided by the higher levels of organization are disrupted, if not eliminated, during

the regeneration period of a commercial forest, especially in clearcut systems. For example, the exposure of saprophytic

organisms to the unfiltered physical environment could be one source of significant changes in mineral nitrogen often

detected in the soil at the start of the regeneration period. Constraints and buffers reestablish as the vegetation reestablishes,

and mineralization returns to preharvest rates. Unless the same hierarchy reestablishes, however, productivity may be changed.

In commercial forestry production, productivity is often defined as the capacity to produce wood. In conifers, two meristems are principally responsible for wood production: the primary meristem on the terminal bud and the cambium. Height

and diameter increments are difficult to correlate with any specific environmental variable; one of the reasons for this difficulty may be that higher levels of organization may buffer meristem activity from variation in the physical environment. 

Results of past studies help identify levels of organization relevant to long-term productivity. Various pine species have

shown a correlation between the length of the terminal bud and the final length of the elongated node produced from that

bud. Research has also shown that the size of the overwintering bud depends on the vigor of the tree. Consequently, leader elongation and the stem appear to represent a hierarchical relationship with the stimuli influencing leader growth being buffered

349
or constrained by the main stem. The crown may buffer

factors influencing stem growth. A recent study reports that

a large percentage of variation in cambial activity at breast

height in several pine species is explained by seasonal

increases in the amount and distribution of the leaf area.

This poster reports preliminary results of the effects of harvesting intensity and site preparation on leader elongation

and stem diameter from a hierarchical perspective. 

In the west Gulf region of the United States, studies are

underway to chronicle the effects of organic matter removal

and soil compaction on growth of the subsequent generation

of loblolly pine (Pinus faeda L.). The experiments differ in

degree of control of treatment application. In the Long-Term

Soil Productivity experiment (LTSP) of the USDA Forest

Service, organic matter removal and soil compaction are

carefully controlled and uniformly applied to the plot. In

the Cooperative Research in Sustainable Silviculture and

Soil Productivity (CRiSSSP) commercial forest studies, the

degree of organic matter removal and soil compaction was

dictated by the equipment used to harvest the stand; however, they include a minimum disturbance treatment comparable to the zero compaction level and the minimum

removal of organic matter treatment of the LTSP study. 

Both the LTSP study and each CRiSSSP installation were

blocked with factorial combinations of the treatments randomly assigned within each block. Height was measured

annually on every tree for the first 5 growing seasons. Measurement intervals varied after age 6. Diameter at breast

height (d.b.h.) was measured on trees greater than 1.37 m

tall. A simple power function was fit with nonlinear regression to the height—age data for each treatment combination across blocks. The first derivative of the fitted equation

was plotted against height to evaluate the hypothesis that

harvesting and site preparation change the hierarchical relationship between the main stem and elongation of the terminal shoot. The hierarchical relationship between cambium

activity and amount and distribution of leaf area was investigated by inspecting the relationship between d.b.h., the

product of leaf area, and the height to the middle of the

crown defined by the uniform-stress principle of stem formation (Dean et al. 2002). Changes in this relationship suggests changes in xylem anatomy and physiological processes

affected by xylem anatomy. 

Harvesting had little if any effect on the relationship

between leader elongation and tree height. With the exception of the first level of compaction in the LTSP study,

compaction and organic matter removal slightly decreased

the leader elongation associated with a given height relative

to the control treatment. Conventional harvesting in the

CRiSSSP studies also reduced leader length per unit height

slightly at two locations but had no effect on the relationship at two other locations. Treatments that substantially

reduced interspecific competition or improved soil nutrition

did appear to significantly change leader elongation for 

a given height. With the exception of one location, these

treatments increased the leader increment expected for a

given height. Based on this analysis, competition control and

fertilization seem more likely candidates than harvesting

for affecting long-term productivity in terms of height

accumulation. 

Harvesting also appears to have little or no effect on the

relationship between d.b.h. and the amount and distribution

of leaf area on the stem. In the LTSP study, while the coefficients for indicator variables representing the various treatment factors indicate a significant effect on the constant,

plots of the equations for the various compaction and

organic matter removal levels lie nearly on top of each

other. Coefficients for indicator variables for harvesting in

the CRiSSSP studies were not significantly different from

zero. The only treatment having a significant effect on the

relationship was fertilization. With fertilized trees, the d.b.h.

associated with a specific combination of leaf area and

height to the middle of the crown was substantially lower

than unfertilized trees with the same combination of leaf

area and height to the middle of the crown. 

Based on these results, harvesting does not seem to affect

these two, simple hierarchical relationships. Treatments

that affect competition or nutrient availability, however, do

seem to increase leader elongation for a given tree height,

and fertilization reduces the d.b.h. associated with a particular combination of leaf area and height to the middle of

the crown. Obviously, longer observation times are required

before such changes in these hierarchical relationships can

actually portend changes in long-term productivity; however, changes observed in this study suggest that hierarchical relationships may be useful in evaluating the effects of

regeneration practices on long-term productivity. 

REFERENCES

Ahl, V.; Allen, T.F.H. 1996. Hierarchy theory: a vision, 

vocabulary, and epistemology. New York: Columbia

University Press. 206 p. 

Dean, T.J.; Roberts, S.D.; Gilmore, D.W.; Maguire, D.A.; 

Long, J.N.; O’Hara, K.L.; Seymour, R.S. 2002. An

evaluation of the uniform stress hypothesis based on

stem geometry in selected North American conifers.

Trees: Structure and Function. 16: 559-568.

350
1 Wildlife Science Group, College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

2 Forest Science Department, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331-5752, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Design Issues for Small Mammal Studies

in Silvicultural Experiments

Robert Gitzen,1 Stephen West,1 Chris Maguire,2 and Tom Manning2

Wildlife studies face design constraints that may be minor problems for other disciplines in large-scale silvicultural

experiments. To illustrate some of these issues, we use the small mammal research component of the Demonstration of

Ecosystem Management Options (DEMO) project, as a case study. The DEMO study is a USDA Forest Service-initiated

experiment examining effects of different patterns and amounts of green-tree retention harvests in mature coniferous forests

of the Pacific Northwest. 

Variability in small mammal communities across the region of interest may reduce the effective sample size for some

analyses, and may contribute to variation in treatment effects across the study region. In the DEMO experiment, forest-floor

small mammals were sampled with pitfall traps during two pretreatment years and during the first and second years after

harvests. Many species were absent from two or four of six study blocks, lowering the number of replicates for analyses

focusing on these species. Some species showed initial trends of opposite sign among study blocks. In a randomized block

study, replication of treatments within blocks would address this community variation, but may require reducing the number

of treatments implemented. 

Wildlife population studies also must consider the number of animals of each focal species present, on average, on each

study site, and the probability of observing each individual. Sampling precision decreases as population size decreases,

reducing statistical power (Skalski and Robson 1992). Moreover, wildlife statisticians increasingly dismiss studies that 

analyze indices of abundance without examining whether capture probabilities (detectability) vary across sites (Anderson

2003). To meet rigorous statistical requirements, high numbers of captures for focal species on each site are needed. In the

DEMO study, even species captured in high numbers overall were found in low abundance at some blocks. For the most

abundant species captured (Sorex trowbridgii), estimated capture probabilities did not differ between forest and harvested

sites, but did show high variation overall. We examine whether estimated detectability differed across treatments for other

commonly captured small mammals in the DEMO study. 

We frequently observed low densities and high local and regional spatial variability in the DEMO small mammal study.

Our observations reinforce the need for replication of treatments locally (within block) and regionally, with experimental

units big enough to support large sampling grids and relatively high captures of focal species. Sampling should conform to

a statistical model allowing estimation of abundance and detectability (e.g., mark-recapture model). These factors may place

strong constraints on the overall design of a silvicultural experiment with wildlife components. 

351
ACKNOWLEDGMENTS

This research is a component of the Demonstration of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of

Washington.

REFERENCES

Anderson, D.R. 2003. Response to Engeman: index values 

rarely constitute reliable information. Wildlife Society

Bulletin. 31: 288-291.

Skalski, J.R.; Robson, D.S. 1992. Techniques for wildlife 

investigations: design and analysis of capture data. San

Diego, CA: Academic Press. 237 p.

352
1 Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada

2 Department of Science Technology and Environment, Royal Roads University, 2005 Sooke Road, Victoria, BC, Canada

3 Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada

4 BC Ministry of Forests, PO Box 9519 Stn Prov Govt, Victoria, BC V8W 9C2, Canada

5 Department of Biology, Okanagan University College, 3333 College Way, Kelowna, BC, Canada

6 Ecosystem Science & Management Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada

7 Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada

8 International Forest Products Limited, #311-1180 Ironwood Street, Campbell River, BC, Canada

9 Department of Microbiology & Immunology, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada

10 BC Ministry of Forests, PO Box 9536 Stn Prov Govt, Victoria, BC, Canada

Balancing Ecosystem Values Proceedings, Poster Abstracts

Potential of Green-Tree Retention as a 

Tool to Maintain Soil Function After Harvest

Susan Grayston,1 Janet Addison,2 Shannon Berch,10 Louise deMontigny,4

Daniel Dural,5 Keith Egger,6 Melanie Jones,5 Jeffrey Lemieux,7 Robin Modesto,8 William Mohn,9

Tochi Panesar,2 Cindy Prescott,1 Suzanne Simard,1 and Diane Srivastava3

The aim of this project is to assess the potential use of green-tree retention as a management tool to maintain soil functioning and site productivity after harvesting. Specifically, the project will identify the diversity and function of the “black

box” of largely unknown soil organisms and changes in these communities with several variable retention harvesting systems to determine (1) if green-tree retention is a suitable management option for maintaining a healthy soil and (2) the size

and density of retention patches most favorable for this purpose. The ultimate goal is to recommend the optimal design of

variable-rentention systems for maintaining soil biodiversity and function.

There are three main questions of interest: (1) Do patches of green-tree retention retain the structure and function of soil

biota of the uncut forest? (2) Is there a minimum retention patch size of green-tree retention necessary to do this? (3) How

far does the effect of a green-tree retention patch extend into the harvested area, and does the “shadow” vary with green-tree

retention patch size?

There is clear evidence that clear-cutting affects the biomass, diversity, and community structure of soil microorganisms

(Jones et al. 2003) and soil invertebrates (Addison et al. 2003). There is also evidence that partial cutting has less of an effect

than clear-cutting on soil organisms (Marshall 2000). It is less clear which type of partial cutting best protects soil biodiversity and functioning. This project brings together a unique, multidisciplinary group of researchers, applying a range of novel

techniques to quantify changes in soil microbial and faunal diversity and function in response to harvesting. The project is

using the second replicate of the STEMS (www.for.gov.bc.ca/hre/stems) installation near Elk Bay, Vancouver Island for the

study. STEMS is a large, multidisciplinary field experiment that compares the ecological, biological and socio-economic

effects of seven silvicultural systems including clear-cut, uncut, group selection, patch cuts, dispersed retention and aggregated retention. The site for the second replicate is CWHxm2—very dry Maritime Coastal Western Hemlock Subzone. The

site series is 05 western redcedar—sword fern, a slightly dry to fresh soil moisture regime and a rich to very rich soil nutrient

regime. The stand is 60 years old and has a site index of 35 m at 50 years. The advantage of using the STEMS experiment

is that it allows us to examine the same soils pre- and post-harvest. We will sample 4 replicate aggregated retention patches

of 4 sizes. In the first year (2004, preharvest) we will sample what will be (1) the center of each retention patch, (2) the

edge of each retention patch and (3) 30 m from the edge of the retention patch. We will also sample four areas of what will

be uncut control and clear-cut at the same distances to obtain a baseline comparison. In the second and subsequent years

353
(2005 on, post-harvest) we will sample the patch center and

then along a transect going 30 m out from the patch edge

into the clear-cut. In year 3 we will compare treatments in

STEMS replicate 1, (5 years, post-harvest), comparing the

patches and associated openings with uncut forest and the

dispersed retention treatment to determine whether the

lighter influence shadow cast by dispersed retention retains

community structure and function across more of the opening than does aggregated retention. 

Microbial community structure will be characterized by

phenotypic and molecular methods and function determined

by using biochemical analyses. DNA will be extracted from

soil and the community profiled through PCR-DGGE

analysis of ribosomal RNA genes (rDNA) (Leckie et al.

2004). PCR primers specific for different phylogenetic

groups will ensure fine resolution. Primers for catabolic

genes characteristic of specific functional groups (e.g., NH4

oxidizers, N2 fixers) will be used to assess diversity of functional genes in different soils and treatments by T-RFLP. We

will use primers designed to amplify the nifH subunit of

nitrogenase, which have been widely used in functional

ecology studies of nitrogen-fixing microbial communities.

Ammonia oxidizing bacterial communities will be targeted

by using primers for the amoA gene. The biomass and

structure of the soil microbial community will be assessed

by analyzing the ester-linked phospholipid fatty acids (PLFA)

composition of the soil because certain groups of microorganisms have different “signature” fatty acids. PLFA will

be extracted from soil, fractionated and quantified using 

the procedure described by Grayston et al. (2004). Microbial

activity and catabolic diversity will be assessed using basal

and substrate induced respiration using a variety of carbon

(C) sources. A rapid microplate enzyme assay system will

be used to compare the key enzymes involved in C, nitrogen (N), and phosphorus (P) cycling in soil. The enzymes

measured will be C (cellulase, B glucosidase, phenol oxidase and lignin peroxidase), N (chitobiosidase, N acetyl

glucosaminidase, urease and protease) and P (acid phosphatase). To assess fungal community structure, abundance

of mushrooms (including chanterelles) will be determined,

DNA extracted and analyzed by RFLP and sequencing. 

Soil mesofauna (mites, collembolan, nematodes) will be

extracted from the soil by using standard wet and dry extraction techniques, and will be identified to species or morphospecies (Addison et al. 2003). A digital library of images will

be constructed to aid identification, allow remote species

confirmations, and facilitate consultation with researchers

world-wide. Functional roles of different species will be

determined by using published literature, analysis of gut

contents and mouth-part morphology. Coastal forests of

Vancouver Island are unique in that they contain not only

native earthworms, but a giant enchytraeid species, in addition to the keystone millipede Harpaphe haydeniana. The

abundance and community structure of these elements of

the soil macrofauna will be determined by using Tullgren

funnels and wet sieving. 

Nutrient availability in the field will be determined close

to each sampling point in the transect, using ion-exchange

membranes ((PRS)TM-probes (Western Ag Innovations,

Saskatoon, SK)), changed monthly during the year. Litter

fall will be measured by collecting litter four times per year

in 0.08 m2 trays placed at the transect sampling points, to

determine if patterns of soil biodiversity are related to the

“litter shadow” of remaining trees. 

The study is designed to run at least 5 years and provide

new knowledge each year. In year 1, the project will identify the diversity of soil microorganisms and fauna in forest

soils, producing molecular and taxonomic databases, culture

collections, digital photographic records and species keys.

In year 2 and subsequent years, the project will produce

information on the initial effects of different retention treatments, which will allow us to make recommendations about

the effectiveness of partial harvesting at maintaining soil

diversity and function and the most appropriate retention

level and spatial arrangement. In year 3, we will be able to

make use of the longer time that replicate 1 of the STEMS

experiment has been in place and make 5-year measurements on the control, clear-cut, dispersed retention, and

aggregate retention treatments. We use these results to test

our initial predications and will adapt our recommendations

on the basis of new results. In year 4, we will use results

and trends to date to identify key indicators soil diversity

and soil functioning and will adapt our monitoring to emphasize these. We will generate hypotheses regarding the link

between the indicators and keystone groups to critical soil

processes, which we will test using manipulative experiments.

REFERENCES

Addison, J.A., et al. 2003. Abundance, species diversity, 

and community structure of Collembola in successional

coastal temperate forests on Vancouver Island. Applied

Soil Ecology. 24: 233-246. 

Grayston, S.J., et al. 2004. Assessing shifts in microbial 

community structure across a range of grasslands differing in management intensity using CLPP, PLFA and

community DNA techniques. Applied Soil Ecology. 

25: 63-84. 

354
Jones, M.D., et al. 2003. Ectomycorrhizal fungal communities in young forest stands regenerating after clearcut

logging. New Phytology. 157: 399-422. 

Leckie, S.E., et al. 2004. Comparison of chloroform fumigation-extraction, phospholipid fatty acid and DNA

methods to determine microbial biomass in forest

humus. Soil Biology & Biochemistry. 36: 529-532. 

Marshall, V.G. 2000. Impacts of forest harvesting on biological processes in northern forests. Forest Ecology

and Management. 133: 43-60.

355
356

1 Cascadien, Inc., 1903 NW Lantana Drive, Corvallis, OR 97330-1016, USA

2 College of Forest Resources, University of Washington, Seattle, WA 98195, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Effects of Green-Tree Retention on the Availability 

of Arthropod Prey to Bark-Gleaning Birds

Juraj Halaj,1 Maria Mayrhofer,2 and David Manuwal2

Green-tree retention is gaining popularity as a forest management tool in the Pacific Northwest. The Demonstration of

Ecosystem Management Options (DEMO) study is the first experimental attempt to provide the needed empirical evidence

to evaluate ecological consequences of this silvicultural model to a wide range of forest organisms. The current study investigated the effects of varying levels and patterns of green-tree retention on the availability of arthropod prey to bark-gleaning birds, primarily the brown creeper (Certhia americana). This ongoing study has a randomized block design and utilizes

three of the existing DEMO blocks in the western Cascade Range of Oregon and Washington. In each block, five 13-ha

treatment units were used in the experiment, including (1) 15-percent aggregated tree retention, (2) 15-percent dispersed

retention, (3) 40-percent aggregated retention, (4) 40-percent dispersed retention and (5) 100-percent retention (control).

Arthropods were collected by using crawl traps installed on live Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees

and snags and with D-vac sampling of tree boles during the brown creeper breeding season from May through August, 2003.

Preliminary results showed that the bark arthropod community was dominated by Collembola (44 percent), Araneae (18

percent), Coleoptera (11 percent) and Hemiptera (10 percent). The total arthropod abundance tended to be higher on live

trees than snags. Spiders appeared especially sensitive to different combinations of green-tree retention. Significant shifts in

the spider guild structure were found among individual treatments and the abundance of these predators was generally higher

in dispersed rather than aggregated treatments and at 15-percent rather than 40-percent tree-retention levels. 
1 College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

2 Pacific Wildland Fire Sciences Lab, USDA Forest Service, 400 N 34th Street, Suite 201, Seattle, WA 98103, USA

3 College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

4 The Institute for Bird Populations, PO Box 1346, Pt. Reyes Station, CA 94956-1346, USA

5 Department of Forest Science, Oregon State University, Richardson Hall, Corvallis, OR 97331, USA

6 Cascadian, Inc., 1903 NW Lantana Drive, Corvallis, OR 97330-1016, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Vegetation Responses to Varying Levels and Patterns of

Overstory Retention: Early Results of the DEMO Experiment

Charles Halpern,1 Donald McKenzi,2 Shelley Evans,3

James Saracco,4 Doug Maguire,5 and Juraj Halaj6

INTRODUCTION

Retention of overstory trees during timber harvest 

has become increasingly common in temperate and boreal

ecosystems as land managers seek to balance the commodity and ecological values of managed forests. In the Pacific

Northwest region of the United States, variable or greentree retention has replaced clearcut logging on federal lands

within the range of the northern spotted owl (Strix occidentalis caurina), with the expressed goal of enhancing the

structural and biological diversity of regenerating forests.

The Demonstration of Ecosystem Management Options

(DEMO) study examines the ecological responses of forest

ecosystems to variable-retention harvests. Specifically, it

tests how the level of tree retention and its spatial distribution (dispersed or aggregated) influence the persistence and

recovery of biological diversity. In this paper, we explore

some of the early responses of forest communities to variation in the level and/or patterns of retention. We focus on

post-harvest mortality of trees and on the responses of two

groups of understory plants likely to be sensitive to changes

in overstory structure—herbs associated with late-seral

forests and ground-layer bryophytes. 

EXPERIMENTAL AND 

SAMPLING DESIGNS

The full experimental design consists of six treatments,

including a control, replicated at each of six locations (blocks)

357

in southwestern Oregon and Washington (Aubry et al. 1999).

In this paper we focus on five of these treatments: the control (100 percent retention), and four that contrast level of

retention (40 vs. 15 percent of original basal area) and its

spatial distribution (aggregated vs. dispersed). Treatments,

assigned randomly to 13-ha experimental units within each

block, were applied as follows: 

• Control: no harvest 

• 40-percent aggregated retention: five 1-ha circular 

aggregates were retained; all merchantable trees in the

surrounding area were cut and removed 

• 40-percent dispersed retention: the same basal area 

was retained as in the 40-percent aggregated retention,

but as dominant and co-dominant trees evenly dispersed

through the treatment area 

• 15-percent aggregated retention: two 1-ha circular 

aggregates were retained; all merchantable trees in the

surrounding area were cut and removed 

• 15-percent dispersed retention: the same basal area was

retained as in 15-percent aggregate retention treatment,

but as dominant and co-dominant trees evenly dispersed

through the treatment area

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

dominated all sites, but forest age, structure, and understory

composition varied considerably among blocks (Halpern et

al. 1999). Treatments were implemented within each block
within a period of 3 to 7 months during 1997 and 1998.

Details on harvest prescriptions, yarding methods, site preparation, and planting can be found in Aubry et al. (1999),

Halpern and McKenzie (2001), and Halpern et al. (2005). 

Within each treatment unit, a systematic sampling grid

(40-m spacing) was established prior to harvest. Nested

vegetation plots were established for sampling overstory

trees, tall shrubs, and ground-layer plants, with the number

and distribution of plots varying by treatment. Overstory

trees were sampled in circular plots of 0.04 ha area. Following harvest, all residual trees >5 cm d.b.h. were tagged,

identified to species, measured for diameter, and assigned

to a canopy class (e.g., suppressed, co-dominant). Post-harvest mortality was assessed annually for 2 to 3 years. Preand post-harvest measurements of shrub height and cover

were taken along four perpendicular transects (total length

24 m). Presence of all herbaceous and bryophyte (moss and

liverwort) species was recorded within 24, 0.1 m2 quadrats

from which species’ frequencies were calculated. Species

in the herb layer were analyzed by seral status (early seral,

forest, and late-seral) to distinguish among taxa with differing successional roles and sensitivities to disturbance. 

RESULTS AND DISCUSSION

Over 2 to 3 years of observation, the rates, patterns and

causes of tree mortality were significantly affected by both

level and pattern of overstory retention. Cumulative mortality was significantly greater at 15 percent than at 40 

percent retention (4.0 to 8.4 percent vs. 1.9 to 3.6 percent,

respectively). Additionally, at both levels of retention, aggregation of trees significantly reduced mortality: cumulative

rates were 1.9 to 4.0 percent in aggregated treatments and

3.6 to 8.4 percent in dispersed treatments. Furthermore,

mortality of co-dominant trees responded to level of retention, while suppressed trees showed a stronger response to

retention pattern. Mortality of co-dominants was greater at

lower levels of retention, particularly in dispersed treatments

(7.3 percent in 15-percent dispersed vs. 1.4 percent in 40

percent dispersed). In contrast, suppressed trees had higher

rates of mortality in dispersed than in aggregated treatments

(8.2 to 10.9 percent vs. 2.2 to 4.9 percent, respectively). These

differences are consistent with frequencies of bole damage

induced by logging activities (17 to 27 percent vs. 2 percent

in dispersed and aggregated treatments, respectively (Moore

et al. 2002)). Among the dominant forms of mortality, wind

damage (windsnap or wind throw) was particularly common in the 15-percent dispersed treatment (4.0 percent vs.

0.4 to 1.1 percent elsewhere). 

In combination, these results lead to two general conclusions: (1) in the short-term, forest aggregates of 1-ha in

size are fairly stable; and (2) at low levels of retention, dispersed patterns are susceptible to logging and wind damage

that can lead to significant mortality, even among co-dominant trees. This latter result is especially relevant to the

design of variable retention harvests in that these larger,

more vigorous trees are typically selected for retention. 

Among vascular understory plants, declines in species

frequency and richness, and changes in species composition

were significantly greater at lower levels of retention. 

Pattern of retention, however, had surprisingly little

effect on understory response. This latter result can be

attributed to extremes in response within the aggregated

treatments: post-harvest changes were small within the

forest aggregates, but declines in adjacent harvest areas

were large and generally greater than those in dispersed

treatments. Late-seral herbs were particularly sensitive to

these effects, experiencing more frequent extirpations from

the harvested portions of aggregated treatments than from

dispersed treatments. These initial responses to harvest are

consistent with patterns of ground disturbance and slash

accumulation which varied markedly among treatments

(Halpern and McKenzie 2001). As effects of disturbance

diminish with time, however, we expect that variation in

overstory structure will play an increasingly important role

in understory recovery. 

Ground-layer bryophytes showed greater sensitivity 

to timber harvest than did vascular plants. Declines in total

cover, richness, and species frequency were large and comparable among treatments. For most measures of response,

declines in thinned plots (dispersed treatments) were as

large as those in cleared plots (harvested portions of aggregated treatments). This is not surprising given the limited

capacity of most shade-adapted bryophytes to tolerate heat

or moisture stress. In contrast, changes within the 1-ha forest

aggregates were generally small (comparable to changes

within the controls). 

Do our results suggest clear differences in vegetation

response to different levels or spatial patterns of retention?

Higher levels of retention clearly reduced wind throw of

isolated or newly exposed trees and loss of herbaceous species

associated with late-seral forests. Responses to pattern of

retention, however, were mixed. Tree mortality was reduced

in aggregated treatments, but the benefit of aggregated

retention for understory plants was predictably localized

within the forest aggregates; in adjacent harvest areas,

358
species showed greater declines or more frequent extirpations than in dispersed treatments. For plant species that

are sensitive to disturbance or dependent on deep shade or

moist substrates, forest aggregates serve as temporary refugia, maintaining local populations through timber harvest.

In the longer term, moreover, they can serve as sources for

dispersal into adjacent harvest areas. Although these functions may be compromised by edge effects, our observations

suggest that patches of 1-ha in size are sufficiently large to

maintain viable populations of most species (see Nelson

and Halpern, this issue). 

ACKNOWLEDGMENTS

This research is a component of the Department of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of Washington.

REFERENCES

Aubry, K.B., et al. 1999. Evaluating the effects of varying 

levels and patterns of green-tree retention: experimental

design of the DEMO study. Northwest Science. 

73(special issue): 12-26. 

Halpern, C.B., et al. 1999. Response of forest vegetation 

to varying levels and patterns of green-tree retention:

An overview of a long-term experiment. Northwest

Science. 73(special issue): 27-44. 

Halpern, C.B., et al. [in press]. Early responses of forest 

understories to timber harvest with varying levels 

and patterns of green-tree retention. Ecological

Applications. 

Halpern, C.B.; McKenzie, D. 2001. Disturbance and postharvest ground conditions in a structural retention

experiment. Forest Ecology and Management. 154:

215-225. 

Moore, J.R., et al. 2002. Effects of varying levels and 

patterns of green-tree retention on amount of harvesting

damage. Western Journal of Applied Forestry. 17:

202–206. 

359
360

1 Weyerhaeuser BC Coastal Group, 517 E.10th St., North Vancouver, BC V7L 2E7, Canada

2 BC Forest Service, 515 Columbia St., Kamloops, BC V2C 2T7, Canada

Balancing Ecosystem Values Proceedings, Poster Abstracts

Biodiversity at the Sicamous Creek Silvicultural Systems Project:

Treatment, Edge and Site Preparation Effects in Subalpine Forest

David Huggard,1 Alan Vyse,2 Walt Klenner,2 and Dennis Lloyd2

A multidisciplinary project at the Sicamous Creek Silvicultural Systems site in interior British Columbia, Canada, examines management alternatives for high-elevation Engelmann spruce–subalpine fir forests, by using a large-scale replicated

experiment. Harvest treatments, each replicated 3 times, include: 10-ha clearcuts and surrounding wide leave strips, arrays

of 1-ha patch cuts with 100 m wide leave strips, arrays of 0.1-ha patch cuts with narrow leave strips, uniform partial cuts

and uncut forest. Each harvest treatment removed a third of the trees. Openings are square and regularly spaced to allow

examination of edge effects into and out of openings unconfounded by changes in stand type or topographic features. Within

each main treatment unit, 30 m x 30 m experimental plots allow comparison of 4 site preparation techniques: standard operational mounding, prescribed burning, organic-layer removal and undisturbed. More than 40 researchers at the site have

examined a wide range of ecosystem components and resources. Here, we collate harvest treatment, site preparation, and

edge effects from biodiversity studies, which include lichens, bryophytes, vascular plants, wildlife habitat structures, pine

marten, spruce grouse, woodpeckers, songbirds, small mammals, and terrestrial invertebrates. 

As expected, no single harvest treatment will best accommodate all species. However, many species showed similar

responses to treatments using 10-ha and 1-ha openings, but different responses to 0.1-ha openings or uniform partial cuts.

Recent operational changes from large clearcuts to 3- to 5-ha openings have reduced public concern about clearcutting, but

may make little difference for most organisms. For many, but not all, species studied at Sicamous Creek, 0.1-ha patch cuts

better retained sensitive species than uniform partial cuts. Maintaining small-scale heterogeneity with patch-cuts or group

selection should be favored over more uniform, continuous cover harvest systems. 

Most species that differed between openings and retained forest showed no edge effects in this naturally open forest type.

A few species, such as three-toed woodpeckers, pine marten and grylloblattid insects, showed positive responses to edges.

Some species associated with retained forest extended 5 to 10 m into openings. These effects support the use of small openings. Short-term negative edge effects were found for spruce grouse, though this species was not disproportionately impacted

by small openings. Reductions in bryophyte abundance were measured up to 50 m into the forest from south-facing edges.

These results suggest that even narrow leave strips and small retained patches can remain as suitable habitat for many forestdwelling species. However, extensive windthrow observed near some edges of 1- and 10-ha openings may extend some

negative edge effects further into the forest over time. 

Site preparation options altered vegetation succession and had some strong initial effects on invertebrates and small

mammals. The current operational practice of mounding was most similar to undisturbed sites, but did have some negative

effects on a few species. These are likely due to mechanical damage to shrubs and logs by the excavator used to do the

mounding, suggesting possibilities to reduce the impact with different machinery or operational practices where mounding

is necessary for silviculture. 

More extensive summaries of the results for harvest treatments, edge effects and site preparation at Sicamous Creek are

available at http://www.for.gov.bc.ca/hfd/ pubs/Docs/En/En63.htm, .../En62.htm, and .../En65.htm
1 Weyerhaeuser BC Coastal Group, 517 E.10th St., North Vancouver, BC V7L 2E7, Canada

2 Weyerhaeuser BC Coastal Group, 65 Front St., Nanaimo, BC V9R 5H9, Canada

Balancing Ecosystem Values Proceedings, Poster Abstracts

Operational Comparisons and Experiments for Monitoring Habitat

Structures in Weyerhaeuser’s Coastal BC Variable Retention

David Huggard,1 Glen Dunsworth,2 and Jeff Sandford2

Weyerhaeuser’s adaptive management program for monitoring and improving variable retention harvesting in coastal

British Columbia, Canada, includes monitoring operational harvest blocks and replicated, randomized experimental treatments. Both the operational and experimental approaches were used for the monitoring because the advantages and disadvantages of each mean that neither one alone is sufficient for a complete program. Randomization in experimental sites

removes some of the confounding effects between treatments and environmental variables typically found in operational

settings. However, with limited replication, confounding with at least a few of the innumerable possible pre-existing site

differences is still inevitable in experimental sites. Experimental sites have the advantage of allowing controlled manipulation of single important variables; the drawback is deciding which of the many possible important variables to study.

Perhaps most importantly, experimental blocks allow a greater range of treatments than operational blocks, which have

greater constraints due to economics and professional risk-aversion. On the other hand, monitoring operational blocks

allows a greater sample size of common treatments to represent a diverse range of ecosystems. It is also necessary for 

determining the weakest points of operational practices and for measuring operational improvement over time. Operational

blocks are readily available, in contrast to typically slow implementation of designed experiments; this enables faster shortterm results to inform managers and to satisfy impatient funding institutions. 

A critical part of learning from the operational monitoring is a sampling design that allows comparisons to address main

management questions. Weyerhaeuser’s design used in coastal British Columbia for operational monitoring of stand-level

habitat structures (trees, snags, logs, cover layers, heterogeneity and others) includes primary comparisons of (1) different

types of variable retention (dispersed, group and mixed), (2) unmanaged benchmarks versus variable retention blocks, (3)

relationships with percentage of retention in variable retention blocks, (4) edge effects into and out of variable retention

reserves, and (5) progress in retaining structures in operational blocks over time. To date, we have monitored structures in

180 variable retention blocks and 56 unmanaged benchmarks across the various ecosystems in coastal British Columbia

under Weyerhaeuser’s tenure. Additional sampling of operational blocks allows secondary comparisons of riparian versus

upland reserves, older clearcuts, older remnant (pre-variable retention) patches and nonharvestable “scrub” sites. We present

5-year results, management feedback, and lessons we have learned about monitoring with designed operational comparisons

and experimental treatments. 

361
1 J.W. Jones Ecological Research Ctr, Rt 2 Box 2324, Newton, GA 39870, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Rediscovering What Works: The Stoddard-Neel Approach 

as a Case Study of Conservation-Oriented Sustainable Forestry

Steven Jack1 and Kevin McIntyre1

Uneven-aged silvicultural approaches are often proposed as appropriate for many forest types in the United States to

provide a sustainable balance of biodiversity and ecosystem “health” in addition to timber products. Several uneven-aged

approaches have been well-documented and widely applied, but most are focused primarily on the production of wood

products in regulated systems. In thinking about appropriate new approaches to sustainable forestry, it is wise to remind

ourselves of approaches that have a long history of achieving the desired objectives. One such example is the Stoddard-Neel

approach developed by Herbert Stoddard and Leon Neel over several decades in open pine-grassland ecosystems (with

particular attention to longleaf pine) on the Southeastern Coastal Plain. The Stoddard-Neel approach is unique not for its

uneven-aged focus or method for selecting trees for removal, but rather in its overall guiding philosophy of resource management and what is selected to remain on the site after each harvest entry. In the Stoddard-Neel approach, the production

of timber and subsequent economic return are byproducts of a central focus on long-term stewardship. That is, rather than a

primary focus on timber management with other resources and amenities as secondary or ancillary, the Stoddard-Neel approach

seeks to preserve all characteristics of the ecosystem and then determine how much timber is available for harvest while

maintaining a balance of ecological, economic, conservation and aesthetic values. We will describe the Stoddard-Neel

approach to forest management, including key tenets and objectives, and provide an example using long-term records 

from one property.

362
1 USDA Forest Service, NCRS, 1831 Hwy 169 E, Grand Rapids, MN 55744, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Extended Rotation Red Pine Stands in Minnesota 

Christel Kern1 and Brian Palik1

Extended rotation stands are rare in most regions, but will likely be more common in the future because of the high conservation value placed on old forests by society. Quantitative data on growth and yield of extended rotation stands are not

common, making economic predictions and ecological expectations difficult to assess. This reflects the practice of basing

rotation age on culmination of mean annual volume increment (CAI) in unthinned stands, without necessarily factoring in

the influence of periodic thinning on growth. We are studying extended rotation red pine (Pinus resinosa Soland.) stands to

better understand the ecological, growth, and yield consequences of managing long-lived species beyond the traditional

rotation age (70 to 90 years for red pine). Our study uses a level of growing stock study that was installed in 85-year-old

red pine stands in 1950. Treatments consist of five levels of residual basal area from 14 to 32 m2/ha. The stands have been

thinned five to seven times. By age 138, mean annual increment had not culminated in the low basal area treatments, holding steady at around 2.5 m3/ha. Mean annual increment in the higher basal area treatments show signs of culmination

between ages 115 to 135 years. Our study reaffirms a growing belief that CAI has limited value for determining rotation

age, given objectives that are more inclusive of conservation and ecological goals. This study also reflects the value of 

long-term experiments, even if established for other reasons, for addressing emerging silvicultural questions.

363
1 J.W. Jones Ecological Research Center, Rt. 2, Box 2324 Newton, GA 39870, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Demonstrating Conservation Forestry: Increasing 

Exposure to Increase Acceptance in the Southeast 

Kevin McIntyre1 and Steve Jack1

There is increasing interest in alternatives to production-oriented resource management among landowners in the

Southeastern Coastal Plain of the United States, where almost 70 percent of the forestland is held in nonindustrial private

ownership. Most nonindustrial private landowners rely on forest consultants and extension programs for forest management

expertise, yet many of these sources of information offer a limited perspective that often focuses heavily on traditional 

production-oriented silvicultural approaches. The Joseph W. Jones Ecological Research Center is located at Ichauway, a 

11 700-ha property in southwestern Georgia that includes 7300 ha of fire-dependent longleaf pine dominated forests. The

Center, with missions in research, conservation and education, is a proponent of conservation-oriented resource management

where no single characteristic or factor is maximized at the expense of other resources, and a balance is sought between

biodiversity values, timber production, wildlife management, and overall aesthetics of the land. To further our mission goals

and to provide relevant information to regional landowners we are developing a 400-ha demonstration area that brings

together many of the components of this conservation management approach in one easily accessible location. Specific

aspects of this demonstration project include (1) multiple and integrated resource management for forest, wildlife and 

biological diversity values, including examples of uneven-aged forestry practices, native groundcover maintenance, wildlife

management (including nongame and endangered species), and ecological restoration; (2) quantification of inputs to and

outputs from the demonstration area, both tangible and intangible, to enable economic comparisons between resource

management alternatives; and (3) implementation of basic and applied research projects within the managed landscape. 

364
1 Yamanashi Forest Research Institute, Masuho, Yamanashi 400-0502, Japan

Balancing Ecosystem Values Proceedings, Poster Abstracts

Contribution of Monitoring Research to Forest Certification and

Ecologically Sustainable Forest Management in the Yamanashi

Prefectural Forest, Central Japan 

Takuo Nagaike1

Yamanashi Prefectural Forest (YPF, 158 000 ha) comprises 35 percent of the Yamanashi prefecture, central Japan.

Because the people of the prefecture now expect ecologically sustainable forest management rather than solely timber production from the YPF, the management policy of the YPF has changed. Yamanashi Forest Ecosystem Monitoring Project,

which is a research project about criteria and indicators based on Montreal Process, was started in 1997 to contribute to ecologically sustainable forest management in the YPF (Nagaike 2002, Nagaike and Hayashi 2003). Because the forest in the

project area is dominated by Larix kaempferi plantations between 40 and 50 years old, it is desirable to change this age

structure. Thus, I studied the effects of stand age on the plant species diversity in plantations. I found the species composition of understory plants in 40- to 50-year-old plantation to be different than in older plantations (Nagaike et al. 2003;

Nagaike and Hayashi, in press). The YPF was certified by Forest Stewardship Council (FSC) in 2003. Although the YPF

received the FSC certification, the assessment team pointed out 17 stipulated conditions. The important points of the conditions were assessment and monitoring of forest management and landscape management. I will discuss the relationship

between the conditions and the project and other related research.

365

REFERENCES

Nagaike, T. 2002. Differences in plant species diversity 

between conifer (Larix kaempfer) plantation and broadleaved (Quercus crispula) secondary forest in central

Japan. Forest Ecology and Management. 168: 111-123. 

Nagaike, T.; Hayashi, A. 2003. Bark-stripping by Sika deer 

(Cervus Nippon) in Larix kaempferi plantations in central Japan. Forest Ecology and Management. 175: 563-

572. 

Nagaike, T.; Hayashi, A. [In press]. Effects of extending 

rotation period on plant species diversity in Larix

kaempferi plantations in central Japan. Annals of Forest

Science.

Nagaike, T., et al. 2003. Differences in plant species diversity in Larix kaempferi plantations of different ages in

central Japan. Forest Ecology and Management. 183:

177-193. 
1 College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195-2100, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Short-Term Responses of Vascular Plants and Bryophytes in 

Forest Patches Retained During Structural Retention Harvests 

Cara Nelson1 and Charles Halpern1

INTRODUCTION

Aggregated retention of overstory trees is now a standard

component of timber harvest prescriptions on federal lands

in the Pacific Northwest. Patches of remnant forest (hereafter, forest aggregates) retained during harvest are thought

to enhance the structural and biological diversity of managed forests, but the extent to which they maintain components of the original understory or promote recovery in

adjacent harvest areas has not been tested. Although small

forest aggregates can have high conservation value, fragmentation or edge influences may diminish their ecological

functions. We examined short-term (1 and 2 year) responses

of understory plants to disturbance and creation of edges

in structural retention harvest units at two sites in western

Washington. Our design uses pre- and post-treatment measurements of permanent plots, allowing us to reliably quantify the spatial pattern, magnitude, and time course of

vegetation response. We pose the following questions: (1)

Do species richness and community composition remain

stable in forest aggregates? (2) Do aggregates retain disturbance-sensitive plants that decline in, or are lost from, adjacent areas of harvest? (3) Within forest aggregates, are there

edge-related gradients in vegetation response (changes in

species richness, community composition, or abundance of

individual species) and, if so, do these gradients correlate

with changes in light availability or disturbance?

FIELD METHODS

This study was conducted in mature Douglas-fir

(Pseudotsuga menziesii (Mirb.) Franco) forests on the

366

Gifford Pinchot National Forest, in conjunction with the

Demonstration of Ecosystem Management Options (DEMO)

experiment (Aubry et al. 1999, Halpern et al. 1999). Sampling occurred in two 13-ha aggregated retention harvest

units, in which five 1-ha (56-m radius) circular forest

aggregates were retained (Nelson and Halpern 2005). In

the surrounding area, all merchantable trees (> 18 cm

diameter at breast height) were cut and removed. Pretreatment sampling was conducted in 1996 and post-treatment

sampling in 1998 and 1999 (years 1 and 2). At each site,

two of the five 1-ha circular aggregates marked for retention were randomly selected. In each of these, we established four perpendicular transects, 81 m in length, which

extended in cardinal directions from the aggregate center

and ended 25 m into the surrounding area to be harvested.

Twelve bands of permanent plots were established along

each transect, eight in the area marked for retention (at distances of 0, 5, 10, 15, 20, 30, 40, and 50 m from the edge)

and four in the area marked for harvest (at distances of 5,

10, 15, and 25 m from the edge). Each band consisted of

five, 1-m2 subplots, within which we estimated the cover

of all vascular plant species, and five 0.1-m2 microplots,

within which we estimated the cover of ground-layer

bryophytes. To explore possible correlates of vegetation

change, we quantified cover of logging slash and disturbed

soil (year 1) and light availability (year 2). Cover of logging slash and disturbed soil was estimated along the interior edge of each band by using the line-intercept method.

Light availability was estimated with a CI-110 digital canopy

imager with a 150-degree lens. Digital photographs were

taken from the end points of each band at a height of 1 m

from the ground surface. Digital images were analyzed

using Scanopy 2.0b software to calculate percent open sky.
ANALYSES

We considered three types of response variables: richness,

community composition, and species abundance. Separate

richness calculations were made for vascular plants classified as forest understory species, those classified as earlyseral species, and bryophyte species. Changes in community

composition were expressed as the percent dissimilarity

(PD) between pre- and post-treatment measurements (vascular plants only), using the quantitative form of Sørensen’s

community coefficient. Abundance was measured as percentage of cover for vascular plants and frequency of occurrence for bryophytes. To standardize for spatial variation in

species richness and abundance prior to treatment, a change

value was computed for each variable as the arithmetic

difference between pre- and post-treatment values.

Responses Within Forest Aggregates and Adjacent

Areas of Harvest

We assessed the comparative responses of vascular

plants in forest aggregates and adjacent areas of harvest by

conducting a series of two-sample t-tests using mean “change

values” (or mean PD for community composition) as the

measure of response. Bryophyte responses were assessed

using a series of paired t-tests to compare pre- and posttreatment values within each environment (harvest areas

and forest aggregates; n = 4). Tests of individual species’

responses were limited to taxa that (1) occurred in at least

three of the four replicates (i.e., forest aggregate/surrounding harvest area pairs) and (2) had greater than 10 percent

frequency (percentage of all possible bands); we refer to

these as “common species.”

Edge-Related Gradients in Vegetation Response and

Physical Environment Within Aggregates

Edge-related gradients in vegetation response were

assessed by calculating Spearman rank correlation coefficients between mean values of vegetation variables (changes

in richness and cover, and PD) and distance from the aggregate edge, with separate analyses for each post-treatment

year. Species-level analyses were limited to the common

taxa noted above. Environmental variables (open sky, logging slash, and disturbed soil) were also correlated with

distance from edge and with vegetation responses.

RESULTS AND DISCUSSION

Differences Between Forest Aggregates and 

Adjacent Areas of Harvest

Compared to harvested areas, forest aggregates showed

minimal change in species richness and composition 2 years

after treatment (Nelson and Halpern 2005). Aggregates

were largely resistant to colonization by early-seral species

and remained stable with respect to forest species richness.

Eight of 29 common vascular plants showed significant

differences in response between environments: seven of

these showed greater magnitudes of decline in harvest areas

than in aggregates; only one showed a significantly greater

increase in abundance in harvest areas than in aggregates.

Ninety percent of bryophytes declined in the harvest area;

however, only five of the eight common taxa showed significant declines. In the short-term, forest aggregates provide refugia for shade-tolerant herbs and ground-layer

bryophytes that are extirpated from, or decline in, adjacent

areas of harvest. Because most forest species do not maintain a viable seed bank, local persistence in and subsequent

dispersal of seeds from aggregates may greatly facilitate

reestablishment of populations in harvested areas.

Gradients in Environment and Vegetation Response

Within Forest Aggregates

Within forest aggregates, increased light availability and

harvest-related disturbance were limited to a 10- to 15-mwide band, leaving approximately 50 percent of the forest

aggregate unchanged for these attributes (Nelson and

Halpern 2005). This large outer band was notably altered,

however, with logging slash covering 38 percent of the

ground surface and open sky roughly double that at the

center of the aggregate. Spatial gradients in community

composition, species richness, and the abundance of individual species correlated to varying degrees with proximity

to forest edge (Nelson and Halpern 2005). Changes in community composition were most apparent at the forest border (0-5 m). We also found slightly reduced richness of

vascular plants at the edge, reflecting declines of some

forest species (with minimal establishment of early-seral

species). We anticipate gradual increases in vascular plant

richness near aggregate edges with time, as early-seral

species become more abundant in adjacent harvested areas.

We found significantly reduced richness of ground-layer

bryophytes with proximity to edge, primarily due to extirpations of less common taxa. Although none of the common

shrub or moss species showed significant responses, 8 of

23 common herbs and 1 of 2 common liverworts declined

near edges. A marked increase from year 1 to 2 in both the

number of species showing significant declines and the

magnitude of decline suggests that edge effects will become

more apparent with time. 

Management Considerations

Identifying minimum sizes for protected areas is an

important issue in conservation biology. Although large

reserves are clearly necessary for many ecosystem processes

and components (e.g., interior-forest microclimate and

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wide-ranging carnivores), smaller forest remnants also may

have high conservation value, especially in landscapes that

are intensively managed for timber production. Our results

suggest that, over short timeframes, aggregates at least 1 ha

in size may provide a refugium for disturbance-sensitive

species and a local dispersal source for recolonization of

harvested areas once microclimatic conditions become suitable for establishment. However, 1-ha remnant patches

may not be large enough to prevent declines of less common

bryophyte taxa. Furthermore, temporal trends suggest that

edge effects judged to be small in the short term may

become more prominent with time. Additional research at

these and other sites in the Pacific Northwest is necessary

to identify the temporal and spatial scales over which forest

aggregates serve their intended ecological functions.

ACKNOWLEDGMENTS

This research is a component of the Department of

Ecosystem Management Options (DEMO) study. Funds

were provided by the USDA Forest Service, PNW Research

Station to Oregon State University and to the University of

Washington.

REFERENCES

Aubry, K.B., et al. 1999. Evaluating the effects of varying 

levels and patterns of green-tree retention: experimental

design of the DEMO study. Northwest Science. 

73(special issue): 12-26.

Halpern, C.B., et al. 1999. Response of forest vegetation 

to varying levels and patterns of green-tree retention: an

overview of a long-term experiment. Northwest

Science. 73(special issue): 27-44.

Nelson, C.R.; Halpern, C.B. [In press]. Edge-related 

responses of understory plants to aggregated retention

harvest in the Pacific Northwest. Ecological

Applications. 

368
1 USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA

2 Currently with Extension Sea Grant, Clackamas County Extension, 200 Warner-Milne Rd., Oregon City, OR 97045, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Effects of Four Riparian Buffer Treatments 

and Thinning on Microclimate and Amphibians in 

Western Oregon Headwater Forests 

Deanna Olson1 and Samuel Chan1,2

We examined the effects on microclimate and amphibians of four riparian buffer widths (ca. 6 m, 17 m, 62 m, 120 m;

untreated control) with thinning to 200 trees/ha in adjacent upland headwater forests, in 30- to 70-year-old stands previously

managed for wood production in western Oregon. Gradients in the summer microclimate (air and soil temperature, relative

humidity), measured at 4 p.m., were evident along transects from streams into the thinned upland forest (N = 6 sites). Mean

(4 p.m.) summer air temperature and relative humidity tended to be ca. 4 °C higher and 15 percent lower respectively, in the

thinned upland forest vs. the control. Riparian buffers averaging as narrow as 17 m wide mitigated the microclimates associated with thinning. Thinning did not affect riparian buffer soil temperature and the temperature of the stream. Amphibian

richness was relatively high (12 spp), but species abundances often were low and spatially variable, which may account for

few treatment effects in stream and bank animals (n = 11 sites), and variable upslope effects (1 of 2 sites). The occurrence

of the headwater-associated torrent salamander at 10 of 11 sites, and 33 of 68 stream reaches was notable. Regardless of

treatment, the steepest change in microclimate was often observed within 5 m from the center of the stream where most

amphibians were captured. To hedge uncertainty in long-term effects of riparian management on headwater resources, a mix

of buffers might be considered for zero-, first-, and second-order streams across subdrainages.

369
1 Department of Landscape Architecture and Institute for a Sustainable Environment, University of Oregon, Eugene, OR 97403, USA

2 Oregon Survey Research Laboratory and Department of Sociology, University of Oregon, Eugene, OR 97403, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Aesthetic Perceptions of Green-Tree Retention Harvests 

in Vista Views: The Interaction of Cut Level, Retention 

Pattern and Harvest Shape 

Robert Ribe1 and Tony Silvaggio2

The scenic beauty of timber harvests affects perceptions of the social acceptability of forest management. Aesthetic 

perceptions of green-tree retention options within harvests were investigated. Study scenes depicted close-up vista views of

clearcuts, an unharvested forest, and a full set of harvests that varied by amount and pattern of green-tree retention and by

the design of cut block shapes. These attributes were tested to explain differences in scenic beauty estimates derived from

331 respondents. Higher scenic beauty was associated with increased dispersed green-tree retention levels. An important

finding was that all levels of aggregated retention, with different amounts of clearcut patches inside harvests, were perceived

as ugly. Dispersed retention levels below about 25 percent are likely to produce various degrees of perceived ugliness,

whereas those with about 25 percent or more retention tend to be seen as beautiful. The design of harvest shapes to look

more irregular, rather than geometric, improved scenic beauty slightly only among harvests with 15 percent or lower retention, irrespective of retention pattern. 

370
1 The Nature Conservancy, 410 N. 4th Street, Mt. Vernon, WA 98273, USA

2 School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195, USA

3 The Nature Conservancy, 217 Pine Street, Suite 1100, Seattle, WA 98101, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Restoration of a Forested Coastal Watershed: 

Ellsworth Creek, Washington 

David Rolph,1 Steven Rentmeester,2 and Jesse Langdon3

In the Willapa Bay area of southwest Washington, The Nature Conservancy is embarking on an ambitious effort to protect and restore a highly productive and biologically diverse coastal watershed. The Ellsworth Creek watershed is a lowelevation coastal rainforest ecosystem with remnant old-growth trees, a rich freshwater aquatic system, and connectivity to

the fertile estuarine waters of Willapa Bay. Although 92 percent of the primary forests in Ellsworth Creek have been logged,

biological inventories indicate that the area still harbors much of its historic biological diversity within refugia found throughout the watershed. Because of its ecological and strategic significance, The Nature Conservancy is dedicated to making

Ellsworth Creek a model for watershed conservation where an adaptive management process closely links active restoration

and scientific investigation.

Specific goals for the conservation and restoration project at Ellsworth Creek include 

1. Managing lands and waters within the project area by using stewardship practices that earn respect and build positive

relationships with the local community and partners throughout the forest management industry. 

2. Restoring the Ellsworth Creek watershed to provide ecologically functional aquatic and upland forest habitats that are

capable of supporting a large diversity of biological communities and species typical of natural primary or late-successional forest landscapes of the Pacific Northwest coast. 

3. Developing a scientifically-driven adaptive management framework for the project and maximizing opportunities for

exporting scientific knowledge and best management practices to other forest and aquatic conservation projects in the

Pacific Northwest.

Ellsworth Creek is a small (2035 ha), highly productive low-elevation watershed comprised of mixed-aged coniferous

forests, a freshwater stream system, and large estuary. Ellsworth Creek supports high-quality remnant low elevation western

redcedar (Thuja plicata Donn ex D. Don), Sitka spruce (Picea sitchensis (Bong.) Carr), and western hemlock (Tsuga

heterophyllaI (Raf.) Sarg.) old-growth forest stands. The approximately 130 ha of old-growth forest represents one of the

largest remaining stands within the Willapa Bay ecosystem and contains five distinct natural forest community types—

including 2 km of riparian associated forests. The watershed strategically connects protected old-growth habitats of the

Willapa National Wildlife Refuge and the Washington Department of Natural Resources Ellsworth Creek Natural Resource

Conservation Area (NRCA), which is located in the adjacent Smith Creek drainage. These conservation areas, together with

the nearby South Nemah NRCA, Bear River restoration project (Bear River Partnership), and Chinook River restoration

project (Sea Resources) create a functional forest, freshwater, and estuarine landscape of approximately 32 800 ha along 

the southern fringe of Willapa Bay.

371
Forests stands in the Ellsworth Creek watershed have

been harvested since the turn of the century, and the remaining old-growth stands are small and fragmented. Approximately 145 ha of old-growth forest remain in the watershed

with much of it being found near the mainstem of Ellsworth

Creek. Some of these stands were selectively harvested in

the past, including by the United States Spruce Production

Division in 1918 during the search for Sitka spruce during

World War I. Additional legacy trees, or small groves, are

found throughout forest stands older than 45 years of age

(470 ha) with these stands typically having a varied composition of Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco), western hemlock, western redcedar, and Sitka

spruce. Forest stands between 20 and 45 years of age (675

ha) have generally been precommercially thinned and are

dominated by planted Douglas-fir with many stands displaying significant sign of Swiss needle cast (Phaeocryptopus

gaeumannii) infestation. Young stands, less than 20 years

old (625 ha), are often composed of extremely dense hemlock and Douglas-fir with stem densities as high as 3200

trees/ha. Existing stand conditions will provide a challenge

for forest restoration; however, the combination of a productive growing environment, diverse stand composition,

and the existence of substantial legacy forest structures

should aid in the recovery and development of forest 

complexity. 

Inventories within old-growth forest habitats at Ellsworth

Creek have documented many avian, amphibian, mollusk,

lichen, and fungi species of state and federal concern.

Marbled murrelets (Brachyramphus marmoratus) are found

in all remnant old-growth patches and also appear to occupy

stands with scattered legacy structures, such as large trees

with mistletoe platforms, to a limited extent. A high diversity of amphibian species is also found in the watershed,

including particularly high population densities of many

regionally endemic amphibian species such as the Columbia

torrent salamander (Rhyacotriton kezeri), Van Dykes salamander (Plethodon vandykei), Dunn’s salamander (Plethodon

dunni), and tailed frog (Ascaphus truei). Initial surveys within the project area, however, have focused on old-growth

forest stands leaving managers with little understanding of

the general distribution of these species. Research and

monitoring is needed to better assess the current distribution of target species and track their dispersal into young

forest stands as those stands mature and develop greater

habitat complexity over the next few decades. 

The freshwater aquatic system contains one of the 

highest spawning densities of chum salmon (Oncorhynchus

keta) in the entire Willapa Bay watershed with close to

8,000 fish reported over a 1.9 km index reach in 2002.

Systematic inventories of other fish species are not known

from the watershed. Anecdotal observations, however, have

indicated significant coho salmon (Oncorhynchus kisutch)

and coastal cutthroat trout (Oncorhynchus clarkii clarkia)

populations. Lamprey (Lampetra spp.) are also present in

the system with smolts being found in mid-order stream

reaches within the watershed. In addition to anadromous

fish, the freshwater stream system provides habitat for

many amphibian species, invertebrates, and other resident

native fish species.

Stream inventory work in 2003 and 2004 has begun to

quantify habitat variables and the spatial distribution of

habitat forming processes within the watershed. Comparing

observed wood loading at Ellsworth with observed values

for unmanaged streams of similar size, headwater stream

segments were found to meet or exceed expected values,

while mainstem segments were depauperate of instream

wood. Headwater stream segments also had higher than

expected wood abundance and a greater number of key

pieces, while wood volume was not significantly different

than observed values for unmanaged streams. Mainstem

segments, however, had significantly lower abundance,

volume, and number of key pieces than would be expected

for unmanaged streams of a similar size. These results are

consistent with the findings of others who have reported an

overall increase in the number of wood pieces but distinct

decreases in the percentage of large instream wood (>50 cm

in diameter) in moderately and intensively harvested watersheds. Threshold relationships also appear in Ellsworth

Creek between drainage area and woody debris abundance,

volume, and the density of key instream wood pieces. Similar

relationships were found for stream gradient, the portion of

channels devoid of alluvium, and the portion of channels

dominated by fine sediments. These relationships suggest

that dominant habitat forming processes are distinct for

stream segments on either side of a threshold of 200 ha in

upstream drainage area. The high variance of habitat variables within headwater stream channels suggests that habitat

formation is dominated by catastrophic events for channels

in these areas. Habitat formation processes downstream of

the threshold appear to be dominated by fluvial and riparian

processes.

Because the watershed has been significantly modified

through a century of timber management, The Nature

Conservancy is expecting active restoration to play a significant role in the recovery of the Ellsworth Creek forest

ecosystem. Other than the impacts from timber management to forest and stream habitats noted above, a legacy of

forest roads threaten aquatic systems with sediment delivery

and hydrologic modification and fragment forest habitat.

372
Road density in the watershed is approximately 3.9 km/km2,

and many roads show signs of imminent failure or other

structural concerns. Road abandonment and upgrades,

therefore, will be an immediate management priority. In

forest stands, variable-density thinning and other silvicultural treatments are expected to be tested as tools for

increasing structural and compositional diversity and hastening the development of late-successional forest attributes. Other active management strategies could include

underplanting with native plant species, the creation of

snags and downed wood, and reintroduction of lichens and

fungi that are associated with late-successional forests. More

specific restoration strategies will be developed as habitat

variables within forest and stream habitats are further quantified during additional inventory work in 2004 and an

adaptive management framework is subsequently developed for the project.

The Nature Conservancy’s proposed restoration strategy

relies on using the best available science so lessons learned

at Ellsworth Creek can be used to inform future forest conservation and management decisions throughout the Pacific

Northwest. To help accomplish this strategy, a scientific

advisory group is being integrated into the early stages of

project design and management. Group members will

have considerable practical research experience in Pacific

Northwest forest ecosystems and come from a variety of

scientific disciplines. The advisory group is expected to

add scientific credibility, state-of-the-art knowledge, and

critical review that will raise the level of on-the-ground

restoration accomplishments and aid in leveraging conservation lessons beyond the project’s boundaries. 

373
1 Oregon State University Extension Forestry, 106 Richardson Hall, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Using Ethics to Educate Consumers 

of Natural Resources 

Viviane Simon-Brown1

At Oregon State University (OSU) and other land-grant institutions, we focus our educational efforts on teaching students to professionally manage natural resources. However, as population, economic, and consumption pressures increase,

addressing the responsibilities of the consumers of natural resources becomes a viable educational tool. Since 1998, the

Sustainable Living Project at OSU has been offering intelligent consumption programming to typical American adults and

older youth, thus creating an ethical foundation to support sustainable management of natural resources. Intelligent consumption is about managing ourselves. It acknowledges the role ethics play in decisionmaking. Contemplating cultural, economic and environmental ethics, considering the barriers to living sustainably, examining national trends, and determining

personal priorities are components of educating the public about their consumer choices.

374
1 Department of Zoology, Oregon State University, Corvallis, OR 97331, USA

2 USDA Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Assessing Threats to the Conservation of Siskiyou 

Mountain Salamanders in Oregon 

Nobuya Suzuki1 and Deanna Olson2

Assessing threats to the conservation of rare species requires enormous time and effort. Our objective was to develop GIS

maps to effectively assess threats to conservation of Siskiyou Mountain salamanders (Plethodon stormi) in southwestern

Oregon. Using GIS layers, we quantified potential risks within 100 and 1000 acres of 5875 random landscape points and

developed GIS maps showing threats to conservation. The threats we assessed included land-use pattern, road density, wildland-urban interface, and catastrophic fire. Cumulative scores of all the risks at the random points were used as z-values to

create 3-dimensional maps. To identify suitable habitats on the landscape, we developed a logistic regression model in which

probability of salamander occurrence was negatively associated with solar illumination. Of 86 conservation areas proposed

by experts based on salamander occupancy and habitat suitability, our maps identified 11 and 21 areas, at scales of 100 and

1000 acres, respectively, as moderate to high risk for the species. Experts may likely overlook threats at a broader spatial

scale without the aid of our maps. We conclude that our maps illustrating threats to conservation can be effectively used 

to select low-risk areas for reserves and to increase consistency and objectivity of conservation planning.

375
1 Department of Forest Vegetation, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba, Ibaraki 305-8687, Japan

2 Iwate Prefectual Forestry Technology Center, Yahaba, Shibagun, Iwate 028-3623, Japan

3 Tottori Prefectual Forestry and Forest Products Research Institute, Inatsune113, Kawaramachi, Yatougun, Tottori 680-1203, Japan

4 Yamanashi Forest Research Institute, Yamanashi 400-0502, Japan

Balancing Ecosystem Values Proceedings, Poster Abstracts

Chronosequencial Changes in Forest Stand Structure 

and Composition—Comparison Between the Post-Harvest 

Secondary Deciduous Broadleaf Forests and the Plantation Forests 

of Evergreen Japanese Cedar (Cryptomeria japonica) 

Hiroshi Tanaka,1 Kaoru Niiyama,1 Mitsue Shibata,1 Tsutomu Yagihashi,1

Hanae Niwa,2 Hiroshi Yabe,3 Atsuko Hayashi,4 and Takuo Nagaike4

INTRODUCTION

Drastic conversion from the primary broadleaf forests,

coppice broadleaf forests, and semi-natural grassland to

conifer (Sugi (Japanese cedar: Cryptomeria japonica) and

Hinoki (Hinoki false cypress: Chamaecyparis obtusa))

plantations occurred between the 1940s and 1980s in the

mountainous area of Japan. To achieve the sustainable

management of the mosaic forest landscape composed of

secondary broadleaf forests and conifer plantation, it is

important to know the contribution of each forest type to

the maintenance of regional biodiversity. To obtain the scientific basis for the management, we addressed the following

two questions: (1) How does conversion from deciduous

broadleaf forest to evergreen conifer plantation impact

species and structural diversity? (2) How does structural

and biological diversity change (recover) in both plantation

and secondary natural forests? Instead of monitoring controlled field experimental sites, we compared sample stands

of different ages scattered in a typical landscape. 

STUDY SITE AND METHODS

The studied forests covered about 200 km2 (ca. 600 to

800 m elevation) of the southern Abukuma mountains, central Japan. We examined forest structure and composition

in 11 post-harvest, secondary deciduous broadleaf forests

(DB) and 11 conifer (Sugi) plantation forests (CP) along a

chronosequence from just after the clear-cutting to mature

condition. A preserved deciduous broadleaf forest was also

376

studied as a reference of old-growth condition. In each forest, we established a 10 m x 100 m belt-shaped study plot

to cover all topographic variation of the forest. Trees and

vines taller than 2 m and larger than 5 cm d.b.h. (diameter

at breast height) were tagged and their g.b.h. (girth at breast

height) was measured for forty 5 m x 5 m quadrats along a

100 m line. A census of forest floor vegetation (vegetation

height < 2 m) was conducted following the Braun-Branque

method for 1 m x 1 m quadrats in each 5 m x 5 m quadrat.

Standing dead stems > 5cm d.b.h. were also tagged and

measured. We also recorded the names of all woody plants

taller than 2 m found in each 5 m x 5 m quadrat. Light condition on the forest floor was also measured by hemispherical photographs taken 1 m above ground in each 1 m x 1 m

quadrat. 

RESULTS AND DISCUSSION

The patterns of changes in structural attributes along 

a chronosequence were different among the attributes and

between the two forest types. The increasing curves of

maximum d.b.h. were almost the same between the broadleaf

stands and conifer plantations, but the increasing curves of

mean d.b.h. were segregated. The patterns of the change in

basal area (BA) showed that tall trees occupy large space

more quickly in the conifer plantations than in the broadleaf

stands. Management practices in plantation forests (improvement felling and thinning) strongly affected the structural

attributes such as stem density and mean d.b.h.. 
According to the growth of trees, number of tree species

> 5 cm d.b.h. increased in the broadleaf stands as stand age

increased, but it was continuously low in the conifer plantations. Number of species (both woody > 2 m height and

forest floor) was the highest at the early stage after the clear

cutting for both types of the forests. As the stand age

increased, the number of woody species gradually decreased

in the broadleaf stands. The number of forest floor species

first decreased and then slowly increased in broadleaf stands.

The number of woody species and forest floor species sharply

decreased and then gradually increased in the conifer plantations. Higher numbers of woody species in the younger

forests were explained by abundant liana and shrub species.

In both the broadleaf stands and the conifer plantations,

the number of forest floor species had negative correlation with stem density (p < 0.05), which reflects the forest

floor light condition.

Ordination and cluster analyses showed the compositional differences of both woody and herbaceous species

between the broadleaf stands and conifer plantation. The

differences in species composition among stands may be

explained largely by the forest age. When forest age

increased, both woody and herbaceous species composition

of the conifer plantation became closer to those of broadleaf

stands. To evaluate the contribution of conifer plantations

and broadleaf stands of different ages to the maintenance

of regional plant diversity, further understanding on the

mechanisms shaping the species composition is necessary.

The number of species which had distributional bias to the

broadleaf stands was larger than that of the species which

had no significant bias to either type of forest or bias to 

the conifer plantations. Functional characteristics of these

species groups should be analyzed for the next step.

377
1 Department of Forest Ecosystem Science, University of Maine, 5755 Nutting Hall, Orono, ME 04469, USA

2 USDA Forest Service, Northeastern Research Station, P.O. Box 640, Durham, NH 03824, USA

3 USDA Forest Service, Northeastern Research Station, RR1, Box 589, Bradley, ME 04411, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Influence of Silvicultural Intensity and Compositional Objectives 

on the Productivity of Regenerating Acadian Forest Stands in Maine 

Robert Wagner,1 Mike Saunders,1 Keith Kanoti,1

John Brisette,2 and Richard Dionne3

A mosaic of young, naturally regenerated stands of largely mixed wood (hardwood-conifer) composition dominate

cutover areas within Maine’s Acadian forest. Tremendous opportunity exists to improve the composition, quality, and

growth rates of these stands while they are in an early successional stage. Two factors determine the long-term outcome of

stand development: silvicultural intensity and compositional objective. Silvicultural intensity is determined by the degree 

of investment in vegetation management and artificial regeneration. Compositional objectives are set by the manager and

determine whether conifer, hardwood, or a mixture of species is desired in the final stand. A long-term study is being established on the Penobscot Experimental Forest in central Maine that will (1) quantify the growth and development of early

successional stands to varying intensities of silvicultural intervention and compositional objectives, (2) document ecophysiological mechanisms affecting the dynamics and productivity of young forest stands, and (3) compare the energy requirements and financial returns associated with early intervention in these cutover stands. A 3 x 3 factorial design with four

replications of 30 m x 30 m (0.09 ha) treatment plots is being used. Three levels of silvicultural intensity (low, medium,

high) and three compositional objectives (conifer, mixed wood, hardwood) are being compared. An initial question being

addressed in the early phase of the study is whether silviculture can be used to mitigate any negative effects of global climate

change on soil temperature and moisture regimes by either encouraging or discouraging the germination and establishment

of various Acadian tree species.

378
1 Department of Fisheries and Wildlife, Oregon State University, Nash Hall, Corvallis, OR 97331, USA

2 USDA Forest Service, Pacific Northwest Research Station Research Station, 3200 S.W. Jefferson Way, Corvallis, OR 97331, USA

Balancing Ecosystem Values Proceedings, Poster Abstracts

Leave Islands as Refugia for Low-Mobility 

Species in Managed Forests 

Stephanie Wessell,1 Richard Schmitz,1 and Deanna Olson2

In the past decades, forest management in the U.S. Pacific Northwest has shifted from one based largely on resource

extraction to one based on ecosystem management principles. Forest management based on these principles involves simultaneously balancing and sustaining multiple forest resource values, including silvicultural, social, economic, and ecological

objectives. Leave islands, or green-tree retention clusters, have been proposed as an alternative silvicultural strategy designed

to sustain the ecological integrity and biological diversity of managed forests. However, pertinent questions regarding the

relation of the physical structure of leave islands to their associated microclimates, flora, and fauna remain largely unanswered. This study evaluates the effectiveness of three sizes of leave islands within a thinned forest matrix relative to thinned

and unthinned forest in providing refugia for low-mobility, ecologically-sensitive species 1 to 5 years following timber

harvest. Specifically, we are examining differences in microhabitat and amphibian, mollusk, arthropod, and vascular plant

abundance and diversity with respect to the size of leave islands in managed forests. By determining habitat correlates of

species and functional group occurrence, we envision that this study will provide vital information regarding leave islands

in managed forest landscapes. Initial results indicate treatment effects relative to microclimate, amphibian and arthropod

density, and vascular plant diversity and ground cover. These results suggest that leave islands may provide short-term

refugia for some low-mobility, ecologically sensitive species in managed forests of the Pacific Northwest.

379
1 Uryu Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Moshiri, Horokanai, 074-0741, Japan

2 Graduate School of Agriculture, Hokkaido University, Tokuda 250, Nayoro, 096-0071, Japan

Balancing Ecosystem Values Proceedings, Poster Abstracts

Effects of Partial Logging on Community Parameters 

in a Northern Japanese Mixed Forest 

Toshiya Yoshida1 and Mahoko Noguchi2

We investigated heterogeneity in community parameters and its determinant factors, with emphasis on effects of human

disturbances (logging activities) in a northern Japanese mixed forest. We used data from 50 study stands (0.25 to 0.50

hectare in area) located in the Nakagawa Experimental Forest, Hokkaido University (lat 44o48’N, long 142o14’E). These

stands were partially logged between 1969 and 1985. Trees with diameter at breast height larger than 6 cm were measured

at intervals of 5 to 8 years. 

In this paper we analyzed data collected over 16 years following a partial logging and calculated demographic parameters

(growth rate, recruitment rate, and mortality; m-2year-1) for three species groups (conifers (mostly Abies sachalinensis),

shade-tolerant hardwoods (mainly Acer mono and Tilia japonica), and shade-intolerant hardwoods (mainly Betula ermanii

and Quercus crispula)). Then we conducted multiple regression analysis to explain causes of the heterogeneity among the

stands. The independent variables considered were sum of basal area (BA: m2ha-1), sum of logged basal area (LOG: m2

ha-1), and species diversity (Shannon H’, based on the basal area). The basal area were increased or decreased during the

15-year period, depending on the stands (the percentage of the term-end basal area to the initial basal area ranged from 70

to 145 percent). Conifers generally showed higher recruitment rate and mortality than hardwoods. The growth rates seemed

to be regulated mainly by a crowding effect (i.e., negative effects of BA as well as positive effects of LOG). In contrast, the

recruitment rates correlated with species diversity better than basal area or LOG. The species diversity also displayed significant correlations with recovery (growth + recruitment - death; m-2 year-1) of both conifers and shade-tolerant hardwoods.

Although the heterogeneity in community parameters seem to be caused by multiple factors including variation of topography

and climate, our study demonstrated the significance of the species diversity on the recovery process of the mixed forests

following a partial logging.

380
Photo by Tom Iraci
382

1 PAUL ANDERSON 2 JOHN BAILEY 3 BRUCE BARE

USFS PNW RESEARCH PNW RESEARCH STATION UNIVERSITY OF 

STATION 3695 93RD AVE SW WASHINGTON

3200 SW JEFFERSON WAY OLYMPIA WA 98512 COL OF FOREST

CORVALLIS OR 97331 (360) 357-5204 RESOURCES, BOX 352100

(541) 758-7786 (360) 956-2346 SEATTLE WA 98195 

(541) 750-7329 john.bailey@fs.fed.us (206) 685-1928

pdanderson@fs.fed.us (206) 616-9069

bare@u.washington.edu

4 WILLIAM BAUGHMAN 5 WILLIAM BEESE 6 LIANE BEGGS

MEADWESTVACO WEYERHAEUSER OSU FOREST SCIENCE

PO BOX 1950 65 FRONT ST 321 RICHARDSON HALL

SUMMERVILLE SC 29483 NANAIMO BC V9R 5H9 CORVALLIS OR 97331 

(843) 851-4629 CANADA (541) 737-8466

(843) 871-1035 (250) 755-3422 liane.beggs@oregonstate.edu

wmb3@meadwestvaco.com (250) 755-3550

bill.beese@weyerhaeuser.com

7 CARRIE BERGER 8 SHANTI BERRYMAN 9 RICHARD BIGLEY

OREGON STATE OSU FOREST SCIENCE DEPT OF NATURAL

UNIVERSITY 321 RICHARDSON HALL RESOURCES

321 RICHARDSON HALL CORVALLIS OR 97331 1111 WASHINGTON ST

CORVALLIS OR 97331 (541) 737-9882 OLYMPIA WA 98405 

(541) 737-6596 (541) 737-1393 (360) 902-1717

(541) 737-1393 shanti.berryman@oregonstate.edu (360) 902-1789

carrie.berger@oregonstate.edu richard.bigley@wadnr.gov

10 LORI BLACKBURN 11 FELIX BOULANGER 12 JEFF BOYCE

USDA FOREST SERVICE UNIVERSITE DE SHERBROOKE MERIDIAN ENVIRONMENTAL

7803 BEAVER CREEK RD DEPT OF BIOLOGIE 1900 N NORTHLAKE WAY, 

PAULINA OR 97751 2500 BOUL. UNIVERSITE STE 211

(541) 477-6900 SHERBROOKE QUEBEC SEATTLE WA 98103

(541) 477-6949 J1K 2R1 CANADA (206) 522-8282

ldblackburn@fs.fed.us (819) 573-0523 (206) 522-8277

felix.boulanger@sympatico.ca jboyce@meridianenv.com

13 GORDON BRADLEY 14 MICHAEL BREDEMEIER 15 LESLIE BRODIE

UNIVERSITY OF UNIVERSITY OF PNW RESEARCH STATION

WASHINGTON GOETTINGEN 3695 93RD AVE SW

BOX 352100 BUESGENWEG 2 OLYMPIA WA 98512 

SEATTLE WA 98195 GOETTINGEN LOWER (360) 357-8581

(206) 616-2874 SAXONY D-37077 (360) 956-2346

(206) 685-0790 mbredem@gwdg.de lbrodie@fs.fed.us

gbradley@u.washington.edu

BALANCING ECOSYSTEM VALUES:

INNOVATIVE EXPERIMENTS FOR SUSTAINABLE FORESTRY

AUGUST 15-20, 2004

FINAL PARTICIPANTS LIST
383

16 STEVE BULKIN 17 FRED BUNNELL 18 LYNN BURDITT

ROGUE RIVER-SISKIYOU UNIVERSITY OF BRITISH GIFFORD PINCHOT NAT’L

PO BOX 520 COLUMBIA FOREST

MEDFORD OR 97501 2036, 2424 MAIN MALL 106001 NE 51ST CIR

(541) 858-2324 VANCOUVER BC V6T 1Z4 VANCOUVER WA 98682 

(541) 858-2330 CANADA (360) 891-5105

sbulkin@fs.fed.us fred.bunnell@ubc.ca (360) 891-5045

lburditt@fs.fed.us

19 ANDREW CAREY 20 JOHN CISSEL 21 ROBERT CURTIS

PNW RESEARCH STATION BUREAU OF LAND MNGT PNW RESEARCH STATION

3625 93RD AVE SW PO BOX 10226 3695 93RD AVE SW

OLYMPIA WA 98512 EUGENE OR 97440 OLYMPIA WA 98512 

(360) 753-7688 (541) 683-6410 (360) 753-7669

(360) 956-2346 (541) 683-6981 (360) 956-2346

acarey@fs.fed.us john_cissel@or.blm.gov rcurtis@fs.fed.us

22 BRIAN D’ANJOU 23 ROBYN DARBYSHIRE 24 DAN DAVIS

BC MINISTRY OF FORESTS USDA FOREST SERVICE CLEARWATER NAT’L FOREST

2100 LABIEUX RD PO BOX 4580 12730 HWY 12

NANAIMO BC V9T 6E9 BROOKINGS OR 97415 OROFINO ID 83544

CANADA (541) 412-6071 (208) 476-8353 

(250) 751-7353 (541) 412-6045 (208) 476-8329

brian.danjou@gems6.gov.bc.ca rdarbyshire@fs.fed.us ddavis@fs.fed.us

25 NATHAN DAVIS 26 LOUISE DE MONTIGNY 27 ROBERT DEAL

OSU DEPT OF FOREST BC MINISTRY OF FORESTS USDA PNW RESEARCH 

SCIENCE PO BOX STN PROV GOVT STATION

321 RICHARDSON HALL VICTORIA BC V8W 9C2 620 SW MAIN ST, SUITE 400

CORVALLIS OR 97331 CANADA PORTLAND OR 97205 

(541) 737-2375 (250) 387-3295 (503) 808-2015

(541) 737-1393 (250) 387-0046 (503) 808-2020

nathan.davis@oregonstate.edu Louise.deMontigny@gems2.gov.bc.ca rdeal@fs.fed.us

28 THOMAS DEAN 29 MARGO DURAN 30 THOMAS EFIRD

LSU AGCENTER USDA FOREST SERVICE USDA FOREST SERVICE PSW

SCHOOL OF RENEWABLE 3200 SW JEFFERSON WAY REGION

NAT RESOURCES CORVALLIS OR 97331 1323 CLUB DRIVE

BATON ROUGE LA 70803 (541) 750-7272 VALLEJO CA 94592 

(225) 578-4216 (541) 750-7329 (707) 562-8976

(225) 578-4227 fayrgirl@hotmail.com (707) 562-9049

fwdean@lsu.edu tefird@fs.fed.us

31 ROBERT FAHEY 32 ROGER FIGHT 33 STEPHEN FITZGERALD

USDA FOREST SERVICE OSU EXTENSION SERVICE

320 SW MAIN ST, STE 400 3893 SW AIRPORT WAY

PORTLAND OR 97205 REDMOND OR 97756 

(503) 808-2004 (541) 548-6088

(503) 808-2020 (541) 548-8919

rfight@fs.fed.us stephen.fitzgerald@oregonstate.edu
384

34 DAVID FORD 35 SAM FOSTER 36 JERRY FRANKLIN

UNIVERSITY OF WASHINGTON USDA FOREST SERVICE UNIVERSITY OF WASHSINGTON

COLLEGE OF FOREST 1400 INDEPENDENCE AVE SW BOX 352100

RESOURCES WASHINGTON DC 20050 SEATTLE WA 98195 

SEATTLE WA 98195-2100 (703) 605-5277 (206) 543-2138

(206) 685-9995 (703) 605-0279 (206) 543-7295

edford@u.washington.edu gfoster@fs.fed.us jff@u.washington.edu

37 LISA GANIO 38 ROBERT GITZEN 39 CINDY GLICK

OSU DEPT OF FOREST UNIVERSITY OF DESCHUTES NATIONAL

SCIENCE WASHINGTON FOREST

321 RICHARDSON HALL PO BOX 352100 1645 E HWY 20

CORVALLIS OR 97331 SEATTLE WA 98195 BEND OR 97701 

(541) 737-6577 (206) 543-7232 (541) 383-5495

(541) 737-1393 bgitzen@u.washington.edu (541) 383-5300

lisa.ganio@orst.edu cglick@fs.fed.us

40 JIM GOUDIE 41 SUE GRAYSTON 42 TEMESGEN HAILEMARIAM

RESEARCH BRANCH, UNIVERSITY OF BC OREGON STATE UNIVERSITY

PO BOX 9519 STN PROV GOVT DEPT OF FOREST SCIENCES 237 PEAVY HALL

VICTORIA BC V8W 9C2 2424 MAIN MALL CORVALLIS OR 97331

CANADA VANCOUVER BC V6T 1Z4 (541) 737-8549 

(250) 387-6535 CANADA (541) 737-3049

(250) 387-0046 (604) 822-5928 hailemariam.temesgen@oregonstate.

jim.goudie@gems4.gov.bc.ca (604) 822-9102 edu

sue.grayston@ubc.ca

43 CHARLES HALPERN 44 THOMAS HANLEY 45 BRUCE HANSEN

UNIVERSITY OF WASHINGTON USDA FOREST SERVICE USFS PNW RESEARCH 

COL OF FOREST 2770 SHERWOOD LN, STE 2- STATION

RESOURCES, BOX 352100 JUNEAU AK 99801 3200 SW JEFFERSON WAY

SEATTLE WA 98195 (907) 586-8811 CORVALLIS OR 97331 

(206) 543-2789 (907) 586-7848 (541) 750-7311

(206) 543-3254 thanley@fs.fed.us (541) 750-7329

chalpern@u.washington.edu bhansen@fs.fed.us

46 TIM HARRINGTON 47 CONNIE HARRINGTON 48 GARY HARTSHORN

USFS PNW RESEARCH PNW RESEARCH STATION WORLD FORESTRY CENTER

STATION 3695 93RD AVE SW 4033 SW CANYON RD

3695 93RD AVE SW OLYMPIA WA 98512 PORTLAND OR 97221 

OLYMPIA WA 98512 (360) 753-7670 (503) 488-2110

(360) 753-7674 (360) 956-2346 (503) 288-4608

(360) 956-2346 charrington@fs.fed.us ghartshorn@worldforestry.org

tharrington@fs.fed.us

49 TROY HEITHECKER 50 PAUL HENNON 51 PETE HOLMBERG

UNIVERSITY OF USFS, FOREST HEALTH WA STATE DEPT OF NAT

WASHINGTON 2770 SHERWOOD LN, 2A RESOURCES

BOX 352100 JUNEAU AK 99801 PO BOX 47016

SEATTLE WA 98195 (907) 586-8769 OLYMPIA WA 98504 

(206) 612-0383 (907) 586-7848 (360) 902-1348

(206) 543-3254 phennon@fs.fed.us (360) 902-1789

theithec@u.washington.edu pete.holmberg@wadnr.gov
385

52 JIM HOTVEDT 53 SUSAN HUMMEL 54 JOHN INNES

WA DEPT OF NAT USDA FOREST SERVICE UNIVERSITY OF BC FOREST

RESOURCES 620 SW MAIN ST, STE 400 RESOURCES

601 BOND RD PORTLAND OR 97205 2045, 2424 MAIN MALL

CASTLE ROCK WA 98611 (503) 808-2084 VANCOUVER BC V6T 1Z4 

(360) 274-2005 (503) 808-2020 CANADA

(360) 274-4196 shummel@fs.fed.us (604) 822-6761

jim.hotvedt@wadnr.gov (604) 822-9106

innes@interchg.ubc.ca

55 STEVE JACK 56 HYON-SUN JEON 57 JOHN JOHANSEN

JOSEPH W. JONES ECO KOREA FOREST RESEARCH USFS SIUSLAW NF

RESEARCH CNTR INST PO BOX 235

RT 2, BOX 2324 SEOUL 130-712 KOREA HEBO OR 97122 

NEWTON GA 39870 kfri@foa.go.kr (503) 392-5131

(229) 734-4706 (503) 392-5143

(229) 734-4707 jjohansen@fs.fed.us

steve.jack@jonesctr.org

58 TERRY JOHNSON 59 ADELAIDE JOHNSON 60 MORRIS JOHNSON

BUREAU OF LAND MNGT USDA FOREST SERVICE USDA FOREST SERVICE

770 SHERWOOD LN, STE 2A 400 N 34TH ST, STE 201

JUNEAU AK 99801 SEATTLE WA 98103 

(907) 586-8811 (206) 732-7852

(907) 586-7848 (206) 732-7801

ajohnson03@fs.fed.us mcjohnson@fs.fed.us

61 STUART JOHNSTON 62 KEITH KANOTI 63 WILLIAM KEETON

US FOREST SERVICE UNIVERSITY OF MAINE UNIVERSITY OF VERMONT

4480 HWY 101, BLDG G 5755 NUTTING HALL SCHOOL OF ENVIRON & 

FLORENCE OR 97439 ORONO ME 04469 NAT RESOURCES

(541) 902-6958 (207) 581-2763 BURLINGTON VT 05405 

(541) 902-6946 (207) 581-4257 (802) 865-5234

srjohnston@fs.fed.us keith_kanoti@umenfa.maine.edu (802) 865-5234

william.keeton@uvm.edu

64 CHRISTEL KERN 65 WAE-JUNG KIM 66 BRIDGET KORMAN

US FOREST SERVICE KOREA FOREST RESEARCH PNW RESEARCH STATION

1831 HWY 169 E INST 3695 93RD AVE SW

GRAND RAPIDS MN 55744 SEOUL 130-712 KOREA OLYMPIA WA 98512 

(218) 326-7133 waejn@foa.go.kr (360) 753-7655

(218) 326-7123 (360) 956-2346

cckern@fs.fed.us bkorman@fs.fed.us

67 TIMO KUULUVAINEN 68 DAVID LARSON 69 JOHN LAURENCE

UNIVERSITY OF HELSINKI USFS PNW RESEARCH USDA FOREST SERVICE

DEPT OF FOREST ECOLOGY STATION 3200 SW JEFFERSON WAY

HELSINKI FIN-00014 3200 SW JEFFERSON WAY CORVALLIS OR 97331 

FINLAND CORVALLIS OR 97331 (541) 750-7357

timo.kuuluvainen@helsinki.fi (541) 754-7485 (541) 758-8791

(541) 750-7329 jalaurence@fs.fed.us

davidlarson@fs.fed.us
386

70 DIANA LIVADA 71 KOSHARE LOMNICKI 72 DAN LUOMA

PNW RESEARCH STATION WA DEPT OF NAT OSU DEPT OF FOREST

3695 93RD AVE SW RESOURCES SCIENCE

OLYMPIA WA 98512 (360) 664-2960 PEAVY HALL 154

(360) 753-7679 koshare.lomnicki@wadnr.gov CORVALLIS OR 97331 

(360) 956-2346 (541) 737-8595

dlivada@fs.fed.us (541) 737-1393

luomad@fsl.orst.edu

73 DAVID LYTLE 74 CHRIS MAGUIRE 75 DOUG MAGUIRE

USDA FOREST SERVICE OSU DEPT OF FOREST OREGON STATE 

1831 E WHY 169 SCIENCE UNIVERSITY

GRAND RAPIDS MN 55744 RICHARDSON HALL DEPT OF FOREST SCIENCE

(218) 326-7105 CORVALLIS OR 97331 CORVALLIS OR 97331 

(218) 326-7123 (541) 737-6571 (541) 737-4215

dlytle@fs.fed.us (541) 737-5814 (541) 737-5814

chris.maguire@oregonstate.edu doug.maguire@oregonstate.edu

76 DOUG MAINWARING 77 GARY MANNING 78 DAVID MANUWAL

OREGON STATE USDA FOREST SERVICE UW COLLEGE OF FOREST

UNIVERSITY PLOUSE RANGER DIST RESOURCES

321 RICHARDSON HALL ROUTE 6 PO BOX 352100

CORVALLIS OR 97331 POTLATCH ID 83855 SEATTLE WA 98195-2100 

(541) 737-8107 (208) 875-1721 (206) 543-1585

(541) 737-1393 (208) 875-1133 (206) 543-3254

doug.mainwaring@orst.edu gjmanning@fs.fed.us auklet@u.washington.edu

79 DAVID MARSHALL 80 ERIC MARTZ 81 MARIA MAYRHOFER

PNW RESEARCH STATION USDA FOREST SERVICE UW COLLEGE OF FOREST

3695 93RD AVE SW 42861 HWY 242 RESOURCES

OLYMPIA WA 98512 POWERS OR 97466 PO BOX 352100

(360) 753-7673 (541) 439-6200 SEATTLE WA 98195-2100 

(360) 956-2346 (541) 439-6217 (206) 543-1585

dmarshall@fs.fed.us emartz@fs.fed.us (206) 543-3254

calypte@u.washington.edu

82 MICHAEL MCCLELLAN 83 KEVIN MCINTYRE 84 RUSS MCKINLEY

JUNEAU FORESTRY JOSEPH W. JONES ECO BOISE CASCADE

SCIENCES LAB RESEARCH CNTR PO BOX 100

2770 SHERWOOD LN, STE 2A RT 2, BOX 2324 MEDFORD OR 97501 

JUNEAU AK 99801 NEWTON GA 39870 (541) 776-6606

(907) 586-8811 (229) 734-4706 (541) 776-6618

(907) 586-7848 (229) 734-6650 russmckinley@boisebuilding.com

mmcclellan@fs.fed.us kmcintyr@jonesctr.org

85 JIM MITAL 86 AL MITCHELL 87 ANDREW MOORES

CLEARWATER NAT'L FOREST CANADIAN FOREST SERVICE OREGON STATE UNIVERSITY

12730 HWY 12 506 W BURNSHIDE RD 321 RICHARDSON HALL

OROFINO ID 83544 VICTORIA BC V8Z 1M5 CORVALLIS OR 97331 

(208) 476-8348 CANADA (541) 737-9882

(208) 476-8288 (250) 363-0786 (541) 737-1393

jmital@fs.fed.us (250) 363-6005 andrew.moores@oregonstate.edu

amitchel@pfc.forestry.ca
387

88 TAKUO NAGAIKE 89 JON NAKAE 90 GRETCHEN NICHOLAS

YAMANASHI FOREST USDA FOREST SERVICE WA STATE DEPT OF NAT

RESEARCH INST 2455 HWY 141 RESOURCES

SAISHOJI 2290-1 TROUT LAKE WA 98650 PO BOX 47016

MASUHO YAMANASHI (509) 395-3480 OLYMPIA WA 98504 

4000502 JAPAN jnakae@fs.fed.us (360) 902-1360

nagaike@pop21.odn.ne.jp (360) 902-1789

gretchen.nicholas@wadnr.gov

91 GARY NORRIS 92 BRIAN PALIK 93 WAYNE PATTERSON

USDA FOREST SERVICE USDA FOREST SERVICE SIUSLAW NATIONAL FOREST

42861 HWY 242 1831 E WHY 169 PO BOX 235

POWERS OR 97466 GRAND RAPIDS MN 55744 HEBO OR 97122

(541) 439-6200 (218) 326-7116 (503) 392-5136 

(541) 439-6217 (218) 326-7123 (503) 392-5143

gnorris@fs.fed.us bpalik@fs.fed.us wpatterson@fs.fed.us

94 CHARLEY PETERSON 95 DAVID PETERSON 96 PAM PHILLIPS

PNW RESEARCH STATION USDA FOREST SERVICE PNW RESEARCH STATION

620 SW MAIN ST, STE 400 1133 N WESTERN AVE 3695 93RD AVE SW

PORTLAND OR 97205 WENATCHEE WA 98801 OLYMPIA WA 98512 

(503) 808-2026 (509) 664-1737 (360) 753-7681

(503) 808-2020 (509) 665-8362 (360) 956-2346

cepeterson@fs.fed.us davepeterson@fs.fed.us pphillips@fs.fed.us

97 NATHAN POAGE 98 KLAUS PUETTMANN 99 VALERIE RAPP

USDA FOREST SERVICE OREGON STATE USDA FOREST SERVICE

620 SW MAIN ST, STE 400 UNIVERSITY PO BOX 3890

PORTLAND OR 97205 321 RICHARDSON HALL PORTLAND OR 97208 

(503) 808-2074 CORVALLIS OR 97331 (503) 808-2132

(503) 808-2020 (541) 737-8974 (503) 808-2130

npoage@fs.fed.us (541) 737-1393 vrapp@fs.fed.us

klaus.puettmann@oregonstate.edu

100 STEVE REUTEBUCH 101 ROBERT RIBE 102 JIM RICE

USDA FOREST SERVICE UNIVERSITY OF OREGON USDA FOREST SERVICE

UNIV OF WASHINGTON, PO 5234 U OREGON 495 NW INDUSTRIAL WAY

BOX 352100 EUGENE OR 97403 ESTACADA OR 97023 

SEATTLE WA 98195 (541) 346-3648 (503) 630-8710

(206) 543-4710 (541) 346-3626 jrrice@fs.fed.us

(206) 685-3091 rribe@uoregon.edu

sreutebuch@fs.fed.us

103 JEFF RICKLEFS 104 MARTIN RITCHIE 105 SCOTT ROBERTS

DEPT OF NATURAL PSW RESEARCH STATION MISSISSIPPI STATE UNIVERSITY

RESOURCES 3644 AVTECH PKWY DEPARTMENT OF FORESTRY

1111 WASHINGTON ST REDDING CA 96003 MISSISSIPPI STATE MS 39762

OLYMPIA WA 98405 (530) 226-2551 (662) 325-3044

(360) 902-1762 (530) 226-5091 (662) 325-3044 

(360) 902-1789 mritchie@fs.fed.us sroberts@cfr.msstate.edu

jeff.ricklefs@wadnr.gov
388

106 DAVID ROLPH 107 MIKE SAUNDERS 108 PAUL SCHWARZ

THE NATURE CONSERVANCY UNIVERSITY OF MAINE OSU FOREST SCIENCE

410 N 4TH ST 5755 NUTTING HALL RICHARDSON HALL

MOUNT VERNON WA 98273 ORONO ME 04469 CORVALLIS OR 97331 

(360) 419-0155 (207) 581-2763 (541) 737-8481

(360) 419-0817 (207) 581-4257 paul.schwarz@oregonstate.edu

drolph@tnc.org mike_saunders@umenfa.maine.edu

109 BOB SEYMOUR 110 LAURA SHEEHAN 111 RYAN SINGLETON

UNIVERSITY OF MAINE BOISE CASCADE CORP OREGON STATE UNIVERSITY

5755 NUTTING HALL 450 PACIFIC AVE N 1230 NE 3RD ST, STE A-262

ORONO ME 04469-5755 MONMOUTH OR 97361 BEND OR 97701

(207) 581-2860 (503) 838-6955 (541) 383-4011

(207) 581-4257 (503) 838-6907 (541) 383-4700

seymour@umenfa.maine.edu LauraSheehan@BoiseBuilding.com ryan.singleton@oregonstate.edu

112 NICK SMITH 113 CLINT SMITH 114 THOMAS SPIES

WEYERHAEUSER BC OREGON DEPT OF USDA FOREST SERVICE

COASTAL GROUP FORESTRY 3200 SW JEFFERSON WAY

65 FRONT ST 5005 THIRD ST CORVALLIS OR 97331 

NANAIMO BC V9R 5H9 TILAMOOK OR 97141 (541) 750-7354

CANADA (503) 842-2545 (541) 750-7329

(250) 755-3517 (503) 842-3143 tspies@fs.fed.us

(250) 755-3550 csmith@odf.state.or.us

nick.smith@weyerhaeuser.com

115 SUSAN STAFFORD 116 CHRISTINE STALLING 117 NOBI SUZUKI

COLLEGE OF NATURAL ROCKY MNN RESEARCH OSU DEPT OF ZOOLOGY

RESOURCES PO BOX 8089 3200 SW JEFFERSON WAY

235 SKOK HALL, MISSOULA MT 59807 CORVALLIS OR 97331

2003 UPPER BUFORD CIR (406) 542-4153 (541) 750-7356 

ST PAUL MN 55108 (406) 329-2124 (541) 750-7329

(612) 624-1234 cstalling@fs.fed.us nobi.suzuki@oregonstate.edu

(612) 624-8701

stafford@umn.edu

118 MARK SWANSON 119 HIROSHI TANAKA 120 KLAUS VON GADOW

FORESTRY & FP UNIVERSITY GOTTINGEN

RESEARCH INST GUSGENWEG 5

MATUNOSATO 1 GOTTINGEN, LOWER

TSUKUBA, IBARAKI 305- SAXONY D-37077

8687 JAPAN kgadow@gwdg.de

hirop@ffpri.affrc.go.jp

121 ALAN VYSE 122 ROBERT WAGNER 123 FRED WAHL

BC FOREST SERVICE UNIVERSITY OF MAINE USDA FOREST SERVICE

515 COLUMBIA ST 5755 NUTTING HALL 201 14TH ST, SW

KAMLOOPS BC V2C 4E5 ORONO ME 04469 WASHINGTON DC 20024 

CANADA (207) 581-2903 (202) 205-0919

(250) 372-8607 (207) 581-2833 (202) 205-1599

vyse@telus.net bob_wagner@umenfa.maine.edu fwahl@fs.fed.us
389

124 STEPHANIE WESSELL 125 CASSIE WIEDEN 126 TOSHIYA YOSHIDA

OSU DEPT OF FISHERIES BLUE LAKE LLC HOKKAIDO UNIVERSITY

AND WILDLIFE 224 NW 13TH, STE 304 MOSHIRI

3200 SW JEFFERSON WAY PORTLAND OR 97213 HOROKANAI HOKKAIDO 

CORVALLIS OR 97331 (503) 937-7437 0740741 JAPAN

(541) 750-7284 (503) 937-8437 yoto@exfor.agr.hokudai.ac.jp

(541) 750-7760 cassie.wieden@wk.com

stephanie.wessell@orst.edu

127 ANDREW YOUNGBLOOD 128 STEVE ZACK 129 ERIC ZENNER

USDA FOREST SERVICE WILDLIFE CONSERVATION UNIVERSITY OF MINNESOTA

1401 GEKELER LN SOCIETY 1530 CLEVELAND AVE N

LAGRANDE OR 97850 219 SE STARK STREET, ST PAUL MN 55108

(541) 962-6530 SUITE 200 (612) 625-3733 

(541) 962-6504 PORTLAND OR 97204 (612) 625-5212

ayoungblood@fs.fed.us (503) 241-3743 ezenner@umn.edu

szack@wcs.org

UNIT CONVERSION TABLE

When you know: Multiply by: To find:

Meters (m) 3.28 Feet

Square meters (m2) 10.8 Square feet

Centimeters (cm) .394 Inches

Hectares (ha) 2.47 Acres

Trees per hectare .405 Trees per acre

Kilometers (km) .62 Miles

Kilogram (kg) 2.205 Pounds

Gram (g) .0352 Ounces

Liters (l) .265 Gallons

Degrees Celsius (C) 1.8C + 32 Degrees Fahrenheit

Feet (ft) .305 Meters

Square feet (ft2) .093 Square meters

Inches (in) 2.54 Centimeters

Acres .405 Hectares

Trees per acre 2.471 Trees per hectare

Miles 1.609 Kilometers

Pounds (lbs) .454 Kilograms

Ounces (oz) .0296 Liters

Gallons (gal) 3.78 Liters

Degrees Fahrenheit (F-32)/1.8 Degrees Celsius
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