DEPAR TMENT OF AGRICULT URE

Large-Scale Silviculture 

Experiments of Western 

Oregon and Washington

Nathan J. Poage and Paul D. Anderson

United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

General Technical Report

PNW-GTR-713

May 2007
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water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

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to a growing Nation.

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Authors

Nathan J. Poage is a research forester, Forestry Sciences Laboratory, 620 SW 

Main Street, Suite 400, Portland, OR 97205 and Paul D. Anderson is a supervisory 

research forester, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, 

OR 97331.
Abstract

Poage, Nathan J.; Anderson, Paul D. 2007. Large-scale silviculture experiments 

of western Oregon and Washington. Gen. Tech. Rep. PNW-GTR-713. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 44 p.

We review 12 large-scale silviculture experiments (LSSEs) in western Washington 

and Oregon with which the Pacific Northwest Research Station of the USDA Forest 

Service is substantially involved. We compiled and arrayed information about the 

LSSEs as a series of matrices in a relational database, which is included on the 

compact disc published with this report and available online at http://www.fs.fed.

us/pnw/research/lsse. The LSSEs are both spatially and temporally large scale, with 

experimental treatment units between 5 and 100 acres and proposed study durations of 20 to 200 years. A defining characteristic of the LSSEs is that a broad range 

of response variables are measured to characterize the response of forest ecosystems to experimental treatments. We discuss the general value and limitations of 

the LSSEs and highlight some possible roles that can be played by the LSSEs in 

addressing management issues emerging at the beginning of the 21st century.

Keywords: Silviculture, large-scale experiment, LSSE, Oregon, Washington, 

Pacific Northwest.
Contents

1 Introduction

1 What Are Large-Scale Silviculture Experiments?

4 How Did the Large-Scale Silviculture Experiments Come About?

5 Methods

12 Results

19 Discussion

19 Value of the Large-Scale Silviculture Experiments

21 Limitations of the Large-Scale Silviculture Experiments

23 Role of Large-Scale Silviculture Experiments in Addressing 

 Emerging Management Issues

25 Conclusions

27 Acknowledgments

28 Metric Equivalents

28 Literature Citations

33 Appendix 1: Capitol Forest Study

34 Appendix 2: Clearwater Study

35 Appendix 3: Demonstration of Ecosystem Management Options Study

36 Appendix 4: Density Management Study, Initial Thinning

37 Appendix 5: Density Management Study, Rethinning

38 Appendix 6: Density Management Study, Riparian Buffer

39 Appendix 7: Forest Ecosystem Study

40 Appendix 8: Long-Term Ecosystem Productivity Study

41 Appendix 9: Olympic Habitat Development Study

42 Appendix 10: Siuslaw Thinning and Underplanting for Diversity Study

43 Appendix 11: Uneven-Aged Management Project

44 Appendix 12: Young Stand Thinning and Diversity Study
Large-Scale Silvicultural Experiments of Western Oregon and Washington

Introduction

In this General Technical Report, we review 12 large-scale silviculture experiments 

(LSSEs) in western Washington and Oregon with which the Pacific Northwest 

Research Station (PNW) of the USDA Forest Service (USFS) is substantially 

involved (fig. 1, table 1). (For the purposes of this report, western Oregon and 

Washington is defined as the part of those states located west of the crest of the 

Cascade Range.) We expand upon previous overview efforts that have provided 

general summaries of many of these LSSEs (e.g., Monserud 2002, Peterson and 

Monserud 2002, Reutebuch et al. 2004). Our goal is to provide forest managers, 

planners, and scientists with detailed information about each LSSE and to organize 

this information in such a way as to facilitate comparison among studies.

This report is organized into several sections. We begin by defining the term 

LSSE and briefly discussing how these 12 LSSEs came to be. We then document 

the LSSEs, including study locations, goals, objectives, and research questions, 

treatments, response variables, and publications. All of this information is stored 

electronically in a series of matrices contained in the compact disc (CD-ROM) 

included with this report. We conclude by discussing the general value and limitations of the LSSEs and the role they can play in addressing emerging management 

issues.

What Are Large-Scale Silviculture Experiments?

Large-scale silviculture experiments are silviculture experiments conducted at 

operational scales. As true manipulative experiments (sensu Hurlbert 1984), LSSEs 

are characterized by such fundamental elements of experimental design as randomization, replication, and unmanipulated, “control” treatments (Monserud 2002). As 

large-scale experiments, the LSSEs reviewed here are designed to be both spatially 

and temporally large in scale. The size range of individual LSSE experimental 

units—typically between 5 and 100 acres, with an average area of approximately 

25 acres—falls within that of operational-scale management units on public lands 

in the Pacific Northwest. Operational-scale experimental units permit inferences 

drawn from the LSSEs to be directly related to management information needs 

without having to scale up research results from smaller experimental plots. The 

LSSEs reviewed here are also temporally large in scale, with proposed study durations of 20 to 200 years. As silviculture experiments, these LSSEs include at least 

one experimental treatment that involves thinning or harvesting of trees to develop 

silvicultural alternatives. (See Helms 1998 for definitions of silviculture, thinning, 

harvesting, and other forestry terms.) A defining characteristic of LSSEs is that 

The size range of 

individual LSSE 

experimental units 

falls within that of 

operational-scale 

management units 

on public lands in the 

Pacific Northwest.
GENERAL TECHNICAL REPORT PNW-GTR-713

Figure 1—Distribution of geographically distinct locations of large-scale silviculture experiments (LSSEs) 

in western Oregon and Washington. Multiple copies of a letter indicate multiple installations of a study. Note 

that each LSSE location shown may include multiple blocks, treatments, and replicates. The LSSE locations 

are superimposed on Omernik’s (1987) level III ecoregions (e.g., Klamath Mountains).

Washington

Oregon

Large-Scale Silviculture

Experiments in Western

Washington and Oregon

I

A

AAC

C

C

C

CC

B

D

D

D

D

D

D

F D

F

F

F

F

F

F

FF

F

F

F

F

E

E

E

E

G

H

H

H

H

I I

I

J

I

I

I

I

J

J L K

L

L

North

Cascades

Puget

Lowland

Eastern

Cascades

Cascades

Willamette

Valley

Coast

Range

Klamath

Mountains Study

Area

B

Olympic

Mountains

Kilometers

Miles

0 50 100 150

0 50 100

N

S

W E

1. Capitol Forest Study (A)

2. Clearwater Study (B)

3. Demonstration of Ecosystem

Management Options Study (C)

4. DMS Initial Thinning Study (D)

6. DMS Riparian Buffer Study (F)

7. Forest Ecosystem Study (G)

8. Long-Term Ecosystem

Productivity Study (H)

9. Olympic Habitat Development

Study (I)

10. Siuslaw Thinning and Underplanting for Diversity Study (J)

11. Uneven-Aged Management

Project (K)

12. Young Stand Thinning and

Diversity Study (L)

E

5. DMS Rethinning Study (E)
Large-Scale Silvicultural Experiments of Western Oregon and Washington

a broad range of response variables (e.g., tree species and size structure, small 

mammals, woody debris, fungi, soils, microclimate, and social perceptions) are 

measured to characterize the response of the forest ecosystem to the experimental 

treatments.

Finally, it should be noted that LSSEs differ from management experiments 

(MEs), another category of experiments conducted by the USFS. The difference 

between the two is that LSSEs are undertaken outside of, or in addition to, planned 

management activities. In contrast, MEs “are well-designed, agency-led administrative studies undertaken as an integral part of management itself and not solely 

as research projects, as part of an active adaptive management process” (IAC 

2006). In a recently implemented ME on the Tongass National Forest, for example, 

precommercial thinnings planned as part of routine timber stand improvement 

activities were implemented as a classically designed experiment. As administrative studies, MEs are “usually financed from the Protection and Management 

appropriation but also may be funded from other specific appropriations, such as 

the Cooperative Work Fund Forest Service (Knutson-Vandenberg)” (USDA FS 

2006). The LSSEs, which are not administrative studies, are funded through a 

much wider range of sources. Finally, scale is another defining characteristic. The 

LSSEs are operational in scale by definition, but no size requirement is placed on 

MEs (although most MEs are conducted by managers using operational resources 

and operational-sized treatment units).

Table 1—Large-scale silviculture experiment codes, names, and appendixes

Study code Study name Appendix

CFS Capital Forest Study 1

CWS Clearwater Study 2

DEMO Demonstration of Ecosystem Management Options Study 3

DMS_IT Density Management Study Initial Thinning Study 4

DMS_RT Density Management Study Rethinning Study 5

DMS_RB Density Management Study Riparian Buffer Study 6

FES Forest Ecosystem Study 7

LTEP Long-Term Ecosystem Productivity Study 8

OHDS Olympic Habitat Development Study 9

STUDS Siuslaw Thinning and Underplanting for Diversity Study 10

UAMP Uneven-Aged Management Project 11

YSTDS Young Stand Thinning and Diversity Study 12

Note: See appendixes 1 through 12 for study-specific details such as initial installation years, primary objectives, 

pretreatment conditions, locations, initial treatments, response variables, study plan citations, and Web sites.
GENERAL TECHNICAL REPORT PNW-GTR-713

How Did the Large-Scale Silviculture Experiments Come About?

The LSSEs reviewed here were initiated in the 1990s in response to the paradigm 

shift that occurred in federal forest management in western Oregon and Washington over the past three decades. This paradigm shift, perhaps best symbolized by 

the implementation of the Northwest Forest Plan (NWFP) in 1994, was characterized by a broadening in management objectives from a wood production focus to 

a focus on the management of forest ecosystems (USDA and USDI 1994). Three 

interrelated issues leading up to the NWFP—clearcutting, old growth, and ecosystem management—are all addressed by the LSSEs.

For the 50 years preceding the NWFP, the dominant harvesting and regeneration method employed in the Douglas-fir region was clearcutting (Curtis et al. 

1998). However, clearcutting—particularly of old growth—met and continues 

to meet with great opposition from substantial portions of the public. In many 

respects, it was clearcutting of old growth—coupled with the growing awareness of 

the biological and ecological uniqueness of old growth—that led to the NWFP. A 

primary motivation for undertaking many of the LSSEs was, therefore, to develop 

alternatives to clearcutting. Correspondingly, a motivation for undertaking many of 

the LSSEs was to determine whether the development of old-growth forest structure 

could be accelerated in young managed forests through silvicultural manipulations 

and treatments.

Ecosystem management, which has been facilitated by the rapidly developing 

science of landscape ecology, emphasizes scale of structure and process, as well 

as the importance of spatial context. For silviculturists and other forest managers, 

the advent of ecosystem management brought several issues to light. There was 

the recognition that the stand metrics commonly used to assess the effects of 

silvicultural treatments under the wood production paradigm were inadequate 

within the context of ecosystem management. Characterization of forest ecosystem 

responses solely in terms of overstory and understory abundance and composition 

of tree or woody competitor species was insufficient. Furthermore, the impacts 

of silvicultural treatments and systems on a broad spectrum of spatially and 

temporally dynamic biological and physical response variables needed to be 

evaluated at larger, more operational scales. Small-plot silviculture studies were not 

adequate to address many of the questions being raised about silvicultural impacts 

on wildlife, birds, plant communities, and other important ecological and social 

response variables. The scale of implementation for silvicultural studies needed to 

be increased in order to encompass the larger scale of spatial and, in some cases, 

temporal variation associated with ecological response variables of interest.

Three interrelated 

issues leading up 

to the NWFP—clearcutting, old growth, 

and ecosystem 

management—are 

all addressed by 

the LSSEs.


Large-Scale Silvicultural Experiments of Western Oregon and Washington

The implementation of the NWFP in 1994 reflected the paradigm shift that 

occurred in federal forest management objectives in the 1990s from a singlecommodity focus on wood production to a focus on ecosystem management. 

Although the LSSEs were not directly established by the NWFP, the NWFP did 

establish the context and—in some cases—provided the resources to initiate 

these LSSEs. A direct influence of the NWFP on LSSE initiation was evidenced 

by the 1994 congressional directives for the USFS to demonstrate ecosystem 

management in western Oregon and Washington. Funding associated with this 

mandate contributed directly to the implementation of three LSSEs discussed here: 

the Demonstration of Ecosystem Management Options (DEMO; app. 3) study, 

the Olympic Habitat Development Study (OHDS; app. 9), and the Young Stand 

Thinning for Diversity Study (YSTDS; app. 12) (Reutebuch et al. 2004).1

For many of the LSSE studies, the assignment of federal lands under the NWFP 

to land-use allocations such as late-successional reserves (LSRs) and riparian 

reserves, each with correspondingly broad management prescriptions, provided 

context in shaping the management information needs as well as science questions 

and objectives. For example, definition of northern spotted owl (Strix occidentalis 

caurina) habitat requirements established a context for management toward development of late-successional forest structure in LSRs. Discussions surrounding the 

definition of late-successional forest structure to be developed in LSRs, definitions 

typically based on the habitat requirements of the northern spotted owl, resulted in 

preliminary criteria for stand characteristics such as snag abundance and quantities of downed coarse wood that have been used explicitly or implicitly as targets 

in some LSSEs. Similarly, the NWFP also established a context for management 

of aquatic and riparian resources. The interim guidelines for delineation of riparian buffers and riparian reserves established under the NWFP are explicitly being 

tested in the one LSSE with a riparian component.

Methods

The amount of raw information associated with each LSSE is enormous. The information we collected about the LSSEs took the form of study plans, publications, 

and personal communications with scientists and managers associated with the 

LSSEs. Our challenge in documenting the LSSEs was to organize this information 

in such a way as to facilitate comparisons among studies. To do this, we identified 

1

Cissel, J. 2006. Personal communication. Study coordinator, Eugene District Office, USDI 

Bureau of Land Management, 2890 Chad Drive, Eugene, OR 97408-7336.
GENERAL TECHNICAL REPORT PNW-GTR-713

common organizational themes in the mass of raw information. These organizational themes fell into five broad categories: (1) study goals, objectives, and questions; (2) study treatments; (3) response variables measured; (4) research products 

(e.g., peer-reviewed journal articles); and (5) general background information about 

each study (e.g., contact information for project personnel, Web sites, study plans, 

timelines).

We used these organizational themes to array the information we had collected 

about the LSSEs into 10 matrices (matrices 1 through 3, 4.1 through 4.3, and 5 

through 8) or spreadsheets in an Excel2 workbook (Microsoft 2001). The organization of the 10 LSSE matrices (available on enclosed CD-ROM) is shown in table 2. 

Each of the 10 matrices can be linked to the others through one or more common 

fields. Typically this linking field is the 3- to 6-character LSSE code included in 

each matrix. The LSSE code generally appears in either the first column or (for 

purely formatting reasons) the first row in each matrix. Thus, the LSSE matrices 

form a relational database.

2

The use of trade or firm names in this publication is for reader information and does not 

imply endorsement by the U.S. Department of Agriculture of any product or service.

Table 2—Large-scale silviculture 

experiment matrices and derived tables 

and figures

 Table or

Matrix	 	 figure

1. Study overviews

2. Goals, questions, objectives

3. Timeline Table 3

4.1–3. Treatments

 4.1. Background Table 4

 4.2. Reduced Table 5

 4.3. Expanded Figure 2

5. Geographic coordinates Figure 1

6. Response variables Table 6

7. Products

8. Contacts

Matrix 1 provides basic background information about each of the LSSEs. In 

addition to the LSSE codes and LSSE names (columns A and B), matrix 1 contains 

general descriptions of study locations, Web sites and overview publications, study 

plan citations, PNW contacts, management contacts, university contacts, whether 

the study plan was peer reviewed and reconciled, and a brief description of the 

steering committee (if one exists) for each LSSE.
Large-Scale Silvicultural Experiments of Western Oregon and Washington

Matrix 2 contains all stated goals, objectives, and questions contained in the 

original and revised study plans of each LSSE (full reference for each citation 

appears in matrix 7). Matrix 3, which is summarized in table 3, illustrates when 

study plans were published, treatments were implemented, and products were 

produced at each LSSE. Treatment information is summarized in matrices 4.1 

through 4.3.

Table 3—Years in which study plans (P) were published, treatments (T) were implemented, and products (L, 

for literature) produced

Study 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Capitol Forest Study P T TL T PTL TL TL TL L

Clearwater Study PT T L L

Demonstration of Ecosystem PT PTL PL L L L L L L L L L

Management Options Study

Density Management Study T PT T TL TL L L L L L PL

Initial Thinning Study

Density Management Study T PT T TL TL L L L L L PL

Rethinning Study

Density Management Study T PT T TL TL TL L L L L PL

Riparian Buffer Study

Forest Ecosystem Study PT T T L L L PL L L L L L L L

Long-Term Ecosystem P T TL T P L L L

Productivity Study

Olympic Habitat Development PT T TL T TL TL T TL TL TL

Study

Siuslaw Thinning and Under- T PTL L L L L L

planting for Diversity Study

Uneven-Aged Management T T T T P L L

Project

Young Stand Thinning and

Diversity Study T T T L L L L L L L

General background information on the treatments applied at each LSSE is 

contained in matrix 4.1 and table 4. Initial installation year(s) indicates the range of 

years over which treatments at an LSSE were installed. The relative arrangement 

of silvicultural treatments across LSSEs is shown in matrix 4.2 and summarized 

in table 5. Matrix 4.2 (table 5) shows treatments in reduced or summary form. 

Treatments are sorted into columns based on the relative degree of overstory 

removal occurring across each treated stand. Matrix 4.3 expands upon the treatment descriptions presented in matrix 4.2 and summarized in table 5 and figure 2. 

To facilitate linking matrices 4.2 and 4.3, a common treatment numbering scheme 

was used in both matrices: 1 = no overstory removal (control), 2 = light overstory 

removal, 3 = moderate overstory removal, 4 = heavy overstory removal, and 5 = 

complete overstory removal (clearcut), with the letters a through d in matrix 4.3 
Table 4—General large-scale silviculture experiment treatment background information 

Replicates 

Pretreat- Planned Treat- Blocks Treat- per Total Future Ad

Initial ment study ment per ments treatment treatments treatments ist

Study installation stand age duration size Locations location per block per block plots planned u

- - - - - - - - - - - Years- - - - - - - - - - Acres Capitol Forest Study 1998–2004 40–70 >60 18–96 3 1 6 1 18 Y 

Clearwater Study 1994–1995 10–13 One rotation 16 2 1 5 1 or 5 30 Y 

Demonstration of 1994–1995 65–170 Long term 32 6 1 6 1 36 Possible 

Ecosystem Management Options Study

Density Manage- 1996–2000 50–70 40–120 30–60 7 1 4 1 28 Y 

ment Study Initial 

Thinning

Density Manage- 1996–2000 60–90 40–120 11–99 5 1 2 1 10 Y 

ment Study

Rethinning

Density Management 1996–2001 50–90 25–40 Various 13 1 2–7 1–4 Various Y 

Study Riparian

Buffer

Forest Ecosystem 1991–1993 55–65 >20 32 1 4 4 1 16 Y 

Study

Long-Term Ecosystem 1996–1998 70–100 200 15–20 4 3–4 4–10 1 100 Y 

Productivity Study

Olympic Habitat 1997–2006 35–62 25 13–25 8 1 1–5 1 16 Possible 

Development

Study

Siuslaw Thinning 1992–1993 30–33 25–30 5–8 3 1 4 1 12 Y 

and Underplanting

for Diversity Study

Uneven-Aged Manage- 1997–2000 35–47 200 20–40 1 4 4 1 16 Y 

ment Project

Young Stand 1994–1996 35–45 Undefined 30–90 3 1–2 4 1 16 Y 

Thinning and

Diversity Study


Large-Scale Silvicultural Experiments of Western Oregon and Washington

Table 5—Number of overstory removal treatments by overstory removal class (and nested 

non-overstory treatments)

No overstory Light Moderate Heavy Complete overstory removal overstory overstory overstory removal

Study (control) removal removal removal (clearcut)

Capitol Forest Study 1 1 2 1 1

Clearwater Study 1 1 3

Demonstration of Ecosystem 1 1 2 2

Management Options Study

Density Management Study 1 1 2 

Initial Thinning

Density Management Study 1 1

Rethinning

Density Management Study 1 1 1 2 

Riparian Buffer

Forest Ecosystem Study 1 (2) 1 (2)

Long-Term Ecosystem 1 1 (2) 2 (2)

Productivity Study

Olympic Habitat Development 1 1 (4)

Study

Siuslaw Thinning and 1 1 1 1

Underplanting for

Diversity Study

Uneven-Aged Management 1 2 1

Project

Young Stand Thinning and 1 2 1

Diversity Study

Note: Light overstory removals retained more than two-thirds of the fully stocked basal area, moderate overstory removals retained one- to two-thirds 

of the fully stocked basal area, and heavy overstory removals retained less than one-third of the fully stocked basal area. The number of non-overstory 

treatments nested within a single overstory treatment is indicated by the numbers in parentheses. At FES, for example, “den augmentation” (i.e., creation 

of dens) and “no den augmentation” are two additional treatments nested within the no overstory removal and moderate overstory removal treatments.

indicating variations on a particular overstory removal treatment. The intent of a 

particular LSSE treatment is described if it was documented in the study plan for 

the LSSE. The initial overstory removal treatment is described in greater detail.

The latitudes and longitudes in decimal degrees of the approximate geographic 

centers of geographically distinct treatment blocks are contained in matrix 5. These 

“coarse-scale” coordinates were used to generate the map of LSSE sites in figure 

1 and appendixes 1 through 12. All latitudes and longitudes are given in decimal 

degrees with the Geodetic Reference System of 1980 and the North American 

Datum of 1983 used as the spheroid and datum, respectively.

The response variables sampled and the products referring to these response 

variables are identified in matrix 6 and summarized in table 6. This list of response 

variables has been compiled from LSSE study plans, written and oral input 

obtained from LSSE scientists and managers, and previous synthesis publications 

(e.g., Monserud 2002, Peterson and Monserud 2002).
10

GENERAL TECHNICAL REPORT PNW-GTR-713

1,000 ft

0 10 20 30 40 50 60 70 80 90 100

60

70

80

90

50

100

Treatment-wide residual basal area (percent)

Matrix as percentage of total treatment area (percent)

CFS (4a)

DEMO (2a)

DEMO (3a)

DEMO (4a)

DEMO (3b)

STUDS (2a)

STUDS (4a)

STUDS (3a)

YSTDS (2a)

YSTDS (2b)

YSTDS (4a)

UAMP (4a)

CFS (2a)

UAMP (2b)

OHDS (3a-d)

LTEP (5a-d)

FES (3a-b)

DMS_RT (3a)

DMS_IT (3b)

DMS_IT (3a)

DMS_IT (2a)

gap (overstory removal)

patch (unthinned)

10 acres

Controls (1a)

(unthinned)

CWS (3a)

CWS (4a)

CFS (5a)

DEMO (4b)

CFS (3a)

CFS (3b)

CWS (4b-c)

LTEP (3a-b)

UAMP (2a)

Scale

Figure 2—Spatial pattern and scale of initial large-scale silviculture experiment (LSSE) overstory treatments. The x-axis indicates the 

treatment-wide percentage of fully stocked basal area retained following the initial overstory removal treatment. The range of treatments 

along the x-axis extends from clearcut treatments (i.e., no basal area retained; e.g., CFS treatment 5a; refer to table 1 for LSSE site codes) 

to unthinned control treatments (i.e., 100 percent of fully stocked basal area retained). The y-axis indicates the percentage of the total 

treatment area made up by the matrix of each LSSE treatment; the matrix is the “background” or dominant feature of the treatment-wide 

spatial pattern. For uniformly thinned stands (e.g., DEMO treatment 3b) and the unthinned controls, the matrix represents 100 percent 

of the total treatment area. Shading indicates residual overstory density, with lighter shades indicating more open residual canopies. 

Average treatment scale for each LSSE is indicated by the size of each treatment unit. Overstory removal gaps and patches of leave trees 

are shown by white and black dots, respectively.
11

Table 6—General summary of response variables shown in detail in matrix 6Response variables CFSa CWS DEMO DMS_IT DMS_RT DMS_RB FES LTEP OHDS STUDS U

Vegetation, over- and midstory Y Y Y Y Y Y Y Y Y Y 

Vegetation, understory Y Y Y Y Y Y Y Y Y Y 

Lichens, mosses, and bryophytes Y Y Y Y Y Y Y Y Mammals, large (e.g., deer) YMammals, arboreal Y Y Y

Mammals, small (e.g., shrew) Y Y Y Y 

Bats Y YBirds Y Y Y Y Y 

Arthropods Y Y Y Y YReptiles and amphibians Y Y Y Y Y YFish YMollusks Y Y Y YSnags Y Y Y Y Y Y Y Y Y 

Woody debris Y Y Y Y Y Y Y Y Y 

Fungi Y Y Y Y Y Y 

Soils Y Y 

Climate Y YMicroclimate Y Y Y Y Y YHydrology and geomorphology Y YForest pathology Y Y

Social perceptions Y Y Y 

Wood production Y Y Y Y Y 

Economics Y Y YOperational factors Y Y Y 

Roads Y YForest floor Y Y Y Y Y Y Y Y Y 

aSee table 1 for study names.
12

GENERAL TECHNICAL REPORT PNW-GTR-713

Product citations are listed in matrix 7. Products include peer-reviewed journal 

articles, reports, book chapters, conference proceedings, theses, educational videos, 

and study plans. For some LSSEs, original study plans have been appended to 

published progress reports or are otherwise available via online Web sites. In other 

cases, original study plans have been appended to formally published establishment 

reports and revised study plans (e.g., Cissel et al. 2006 for the Density Management 

Study (DMS)). Only products with a reasonable probability of being located by 

readers have been cited in matrix 7. For example, abstracts of posters included in 

published conference proceedings are cited, but the original poster will not be cited 

in most cases.

Matrix 8 contains the current contact information (i.e., address, e-mail, telephone) for scientists and managers currently associated with the LSSEs.

We sent the original draft of the LSSE matrices to the principal investigators 

and management liaisons of each study for review and, where necessary, correction. 

We reviewed the edited matrices with the principal investigators and management 

liaisons before compiling the final version of the LSSE matrices, LSSE_matrix.

xls. A copy of LSSE_matrix.xls is included in the CD-ROM published with the 

hardcopy version of this report and is also available online from the LSSE Web site 

maintained by the PNW (http://www.fs.fed.us/pnw/research/lsse/, last accessed 

on February 14, 2007). Updates to the LSSE matrices will be posted on the LSSE 

Web site as time and funding permit.

To enable readers to gain an overview of the matrices while reading the report 

without having to continually shift between the hardcopy and electronic media, we 

have included portions or summaries of most of the LSSE matrices as tables and 

figures in the printed body of this report. Table 2 identifies which tables and figures 

correspond to which matrices. Additionally, we created summaries of each study 

and included them as appendixes at the end of this report (app. 1 through 12).

Results

The LSSEs are located on public forest lands managed by the USFS, USDI Bureau 

of Land Management (BLM), U.S. Department of Defense, and the Washington 

State Department of Natural Resources (WADNR) (matrix 1). The majority of 

LSSEs have study sites confined to single forests. Exceptions to this are the three 

components of DMS, DEMO, and the Long-Term Ecosystem Productivity study 

(LTEP; app. 8), which have study sites located at multiple forests. The DEMO study, 

for example, has sites located on two national forests and one state forest. The 

LSSEs located on multiple forests, districts, or resource areas require additional 

administrative effort.
13

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Web sites exist for all of the LSSEs (matrix 1). However, the amount of information available online for each LSSE covers a range of quality and quantity. Given 

that (1) the earliest initial treatment year for any LSSEs was 1992, (2) treatments 

were still being installed in 2006 at some LSSEs, and (3) the process of measurement, remeasurement, analysis, and publication is a lengthy one, few if any data 

are available online for any of the LSSEs. A notable exception to this is DMS, for 

which some data are publicly available online at http://ocid.nacse.org/nbii/density/ 

(last accessed November 21, 2006).

Many of the stated goals, objectives, and questions are quite general in nature 

(matrix 2). Few are posed in explicitly testable terms. The only two LSSEs with 

one or more goals or objectives formulated as testable statements are the Forest 

Ecosystem Study (FES; app. 7) and OHDS. Despite these potential shortcomings, 

it is clear from the stated goals, objectives, and questions that the three interrelated 

issues noted in the Introduction as leading up to the NWFP—clearcutting, old 

growth, and ecosystem management—are all addressed by the LSSEs. For example, 

all of the LSSEs examine silvicultural alternatives to clearcutting. Over two-thirds 

of the LSSEs address the question of whether or not the development of late-successional/old-growth (LSOG) forest structure(s) can be accelerated in young managed 

forests through silvicultural manipulations and treatments. Although the LSOG 

theme clearly addresses management needs associated with the LSRs established 

under the NWFP, only two of the LSSEs explicitly define LSOG structural criteria 

with which to judge relative success or failure. The two LSSEs that explicitly define 

LSOG structural criteria are the initial thinning component of DMS (DMS_IT; app. 

4) and the rethinning component of DMS (DMS_RT; app. 5).

Several of the LSSEs have completed revisions to their original study plans 

(matrix 3, table 3). Installation of treatments required more than a year at all LSSEs. 

All LSSEs have generated products, an increasing number of which are journal 

articles and other peer-reviewed publications.

Also shown in matrix 3 (but not in table 3) are key events such as the listing 

of the northern spotted owl in 1990 and the convening of the Forest Ecosystem 

Management Assessment Team in 1993 (FEMAT 1993), which led to the adoption of the NWFP in 1994. In 2003, PNW scientists and managers collaborated 

in the development of an International Union of Forestry Research Organizations 

(IUFRO) working group focused on large-scale ecological experiments. A meeting held in Davos, Switzerland, brought together a core group of researchers from 

North America, Asia, and Europe to examine the role of large-scale experimentation in forest management research (Szaro and Peterson 2004). In August 2004, 

the scope of this endeavor was expanded through an IUFRO workshop held in 

It was evident from 

these events that 

the vast majority of 

operational-scale 

silviculture studies are 

being conducted in 

the Pacific Northwest 

region of North 

America.
14

GENERAL TECHNICAL REPORT PNW-GTR-713

Portland, Oregon (Peterson and Maguire 2005). It was evident from these events 

that the vast majority of operational-scale silviculture studies are being conducted 

in the Pacific Northwest region of North America. It was also evident that there are 

substantial differences among researchers’ concepts of large-scale multidisciplinary 

research. Whereas the PNW studies focus on large-scale treatment units, many of 

the European studies are developed around relatively smaller treatment units but 

address more response variables.

Events such as the IUFRO workshops highlight the potential breadth of information being generated regionally and globally. Although individual studies provide answers to important questions, each has a scope of inference dictated by the 

particular range of treatments imposed, response variables measured, geographic 

distribution of replicates, and statistical power associated with its design. When 

they are arrayed collectively, it is apparent that many of the studies share common 

questions with more or less common approaches. To maximize the collective value 

of these efforts requires communication among scientists engaged in these studies 

and between scientists and managers defining the information needs and objectives 

underlying the studies. An initial attempt to develop an organized forum for crossstudy communication was presented at the 2005 North American Forest Ecology 

Workshop. A Web-based center of information was proposed to foster communications among scientists with a long-term agenda of facilitating collaboration and 

promoting synthesis across studies (Puettmann et al. 2005). In April 2006, a 2-day 

workshop in North Bonneville, Washington, brought together over 35 scientists, 

management liaisons, and agency administrators to discuss the 12 LSSEs.

Treatments at most LSSEs were installed within a fairly narrow timeframe, 

generally within a 2- or 3-year period that includes both pretreatment data collection and treatment implementation (matrix 4.1). An exception to this is OHDS, 

where 10 years were required to install the full set of treatments at the eight OHDS 

locations on the Olympic Peninsula. At the time of treatment, the majority of LSSE 

stands were fully stocked, even-aged stands consisting primarily of Douglas-fir 

(Pseudotsuga menziesii (Mirb.) Franco). At most LSSEs, stand ages at the time of 

initial treatment fell between 25 and 80 years. The Clearwater Study (CWS; app. 2), 

with a pretreatment range of stand ages of 10 to 13 years, contained the youngest 

stands treated. Despite the CWS having the youngest pretreatment stand ages, one 

of the CWS objectives is to “[a]ccelerate the development of characteristics associated with late-successional forests” (Harrington and Carey 1997).

The majority of LSSEs may be viewed as long-term studies (matrix 4.1). 

Some, such as DMS_IT and the Uneven-Aged Management Project (UAMP; app. 

11), have planned study durations in excess of 100 years. It is unknown whether 
15

Large-Scale Silvicultural Experiments of Western Oregon and Washington

such an ambitious effort can be sustained financially. However, it is clear that future 

treatments were envisioned for the majority of LSSEs experiments. For example, 

Curtis et al. (2004) explicitly noted that subsequent entries would occur on a 

15-year cycle in the patch cut and group selection treatments of CFS. This 15-year 

cycle has subsequently been revised down to a shorter, 10-year cycle.3

The relative spatial scale and geographic extent of each LSSE are captured 

by the descriptors “administrative unit,” “location,” “blocks,” and “treatments” 

(matrix 4.1). In this assessment, we consider national forest districts, BLM resource 

areas, and state forests as administrative units, the coarsest spatial scale. “Location,” reflecting a finer spatial scale than “administrative unit,” indicates a spatially 

clumped collection of treatment plots within a particular forest district or resource 

area. For example, DEMO has blocks of treatments on three forests: the Umpqua 

National Forest in Oregon and the Gifford Pinchot National Forest (GPNF) and 

Capitol State Forest in Washington. Three blocks of DEMO treatments are located 

on the GPNF, with one block on each of three GPNF districts, which we consider 

administrative units. On the GPNF, blocks of treatments only occur at one location 

within each of the three administrative units (i.e., one block per GPNF district). 

The two blocks of DEMO treatments on the Umpqua National Forest (UNF), in 

contrast, occur at two locations on the same administrative unit (i.e., two blocks per 

UNF district). Blocks identify groups of replicated treatments. Replicates reflect 

the finest spatial scale. The total number of treatment plots for each LSSE is arrived 

at by multiplying (assuming a balanced design) locations × blocks per location × 

treatments × number of replicates (matrix 4.1).

The treatment plots of most LSSEs reflect the variability in slope, elevation, 

and aspect found in the general area in which each LSSE is located. In other words, 

treatment plots represent “typical” management units. Because of the experimental 

nature of LSSEs, however, several LSSEs do not reflect operational constraints. 

For example, additional effort was involved marking trees for the variable-density 

thinnings at DMS_IT, FES, and OHDS; even so, the variable-density thinnings 

were still economical. In other cases, harvesting practices were unique. At the 

Siuslaw and Underplanting for Diversity Study (STUDS; app. 10), loggers used 

smaller yarders than those typically used in the Coast Range. Finally, “typical” 

administrative constraints were relaxed for some LSSEs. For example, the riparian 

buffer component of DMS (DMS_RB; app. 6) employed riparian buffer width 

treatments that would not have been permitted ordinarily.

3Marshall, D. 2006. Personal communication. Biometrician, Weyerhaeuser Company 

WTC 1A5, P.O. Box 9777, Federal Way, WA 98063-9777.
16

GENERAL TECHNICAL REPORT PNW-GTR-713

Many treatment regimes or silvicultural prescriptions (each composed of different silvicultural treatments) of the stand-level studies can be roughly categorized 

into evaluations of even-age and uneven-age silvicultural systems. For example, 

the UAMP treatment regimes include three alternatives in which repeated periodic 

harvest entries are prescribed into perpetuity. Initially these entries constitute a 

conversion from a single-cohort to multiple-cohort stand structure. Subsequently, 

repeated entries generate new cohorts while maintaining continuous cover. 

Although cutting cycles exist, no rotation lengths are defined per se for UAMP; 

the three UAMP continuous-cover active management approaches represent three 

different uneven-age silvicultural systems. The Capitol Forest Study (CFS; app. 

1) includes four even-age treatment regimes differing in regeneration method and 

length of rotation, each expected to differ in structural development, growth, and 

yield. The CFS also includes patch-wise selection and group selection alternatives 

leading to uneven-age management regimes.

Several of the studies on federal lands address a management scheme that 

cannot be easily categorized as even-age or uneven-age. For example, STUDS 

addresses management approaches for application to young even-aged stands 

being managed as LSRs under the NWFP. The silvicultural treatments in STUDS 

are designed to move stands from simple, even-age structure to more complex, 

multicohort structure. However, this is done with the caveat that once the stands 

reach a threshold age (which is defined as a surrogate for mean tree size), further 

manipulative entries will cease. The opportunity to introduce more than one or 

two additional cohorts between ages 35 and 80 years is limited. Thus, although 

this represents a conversion from an even-age system, the restriction on active 

management beyond a threshold age does not allow for management in an unevenage system. Further, there remains reasonable question as to whether the conversion 

process initiated in one or two thinning entries can be maintained, or will the 

stands revert to an even-age condition without subsequent entries? Although the 

development of desired stand structures and ecological services from these young 

even-age Douglas-fir forests by means of forest reserve designation and passive 

management has not yet been demonstrated, the LSSE untreated controls provide 

demonstrations of the efficacy of passive management.

Most of the studies were initiated with a single prescribed entry; however, multiple entries were explicitly prescribed in the study plans of the CFS (Curtis et al. 

2004) and UAMP (Tucker et al. 2001). The CFS and UAMP were, from the outset, 

evaluations of alternative prescriptions for silvicultural systems. Curtis et al. (2004) 

defined a silvicultural system as “a planned program of silvicultural treatments covering the life of a stand, from regeneration through intermediate operations to final 
17

Large-Scale Silvicultural Experiments of Western Oregon and Washington

removal.” This definition of a silviculture system is similar to “classic” definitions 

of silvicultural systems found in silviculture textbooks such as Matthews (1989), 

Nyland (1996), and Smith et al. (1997).

Several of the LSSEs (e.g., DMS_IT, DMS_RT, DMS_RB, and STUDS) are 

currently in preparatory stages for second entries. Thus, these studies are transitioning from evaluations of silvicultural treatments to evaluations of silvicultural 

systems. With the publication of the revised study plan for DMS_IT, DMS_RT, and 

DMS_RB (Cissel et al. 2006), these studies may rightly be regarded as evaluations 

of silvicultural systems.

Matrix 4.2 and table 5 both indicate, for example, that DEMO has one 

unthinned control (i.e., no overstory removal treatment), one light overstory 

removal treatment, two different moderate overstory removal treatments, one heavy 

overstory removal treatment, and one complete overstory removal treatment (i.e., 

clearcut). It must be stressed that “light,” “moderate,” and “heavy” reflect relative 

categories of overstory removal because different LSSEs used different measures 

to define stand density (e.g., basal area, trees per acre, relative density). In general, 

however, heavy overstory removals retained less than one-third of the fully stocked 

basal area, moderate overstory removals retained one- to two-thirds of the fully 

stocked basal area, and light overstory removals retained more than two-thirds of 

the fully stocked basal area.

All of the LSSEs contain treatments without overstory removal, i.e., unthinned 

“control” treatments (matrix 4.2, table 5). However, only CFS and LTEP include 

clearcut treatments in which all trees with diameters larger than some small, 

minimum diameter were felled. Of these two, only CFS has treatments in all five 

overstory removal classes. One-third of the LSSEs have treatments in each of the 

four overstory removal classes other than the clearcut treatment.

In some cases, two treatments at an LSSE might have similar overall levels of 

overstory removal, but the treatments were considered different because of differences in the spatial patterns of overstory removals and other treatments (matrix 

4.2). At DEMO, for example, the 40-percent aggregated retention and 40-percent 

dispersed retention treatments are both considered medium overstory removals. The 

spatial patterns of these two medium overstory removals are very different, however. In contrast to matrix 4.2, the total number of different overstory treatments is 

simply shown in a single row in table 5. The number of non-overstory treatments 

nested within a single overstory treatment is indicated by the number in parentheses 

in table 5. At FES, for example, “den augmentation” (i.e., creation of dens) and “no 

den augmentation” are two additional treatments nested within the no overstory 

removal and moderate overstory removal treatments (table 5).

In some cases, two 

treatments at an LSSE 

might have similar 

overall levels of 

overstory removal, but 

the treatments were 

considered different 

because of differences 

in the spatial patterns 

of overstory removals 

and other treatments.
18

GENERAL TECHNICAL REPORT PNW-GTR-713

The wide range of density measures used in different LSSEs is apparent from 

the information summarized in matrix 4.3. Curtis’s (1982) relative density was used 

in CFS, FES, and UAMP. Number of trees per acre was used by CWS, DMS_IT, 

DMS_RT, DMS_RB, LTEP, STUDS, and YSTDS. Basal area was used by DEMO 

and OHDS. Additional treatments described are planting, spatial distribution of 

coarse woody debris, spatial distribution of logging slash, organic matter removal, 

and road removal.

The initial LSSE treatments were variable in terms of the intensity and spatial 

pattern of overstory removal and the scale of treatment application (fig. 2). The 

x-axis in figure 2 indicates the treatment-wide percentage of fully stocked basal 

area retained following the initial overstory removal treatment. (Treatments for all 

LSSEs except DMS_RB are shown in fig. 2.) The range of treatments along the 

x-axis extends from clearcut treatments (i.e., no basal area retained) to unthinned 

control treatments (i.e., 100 percent of fully stocked basal area retained). The y-axis 

indicates the percentage of the total treatment area made up by the matrix of each 

LSSE treatment. The matrix is the “background” or dominant feature of the treatment-wide spatial pattern. For uniformly thinned stands (e.g., DEMO treatment 3b) 

and the unthinned controls, the matrix represents 100 percent of the total treatment 

area. Shading indicates residual overstory density, with lighter shades indicating 

more open residual canopies. Treatment scale for each LSSE is the average size of 

each treatment unit. The square labeled “10 acres” at the bottom of figure 2 represents an area of 10 acres.

To illustrate, the two clearcut treatments—CFS treatment 5a and LTEP treatments 5a through d—are shown as white squares in the upper left corner of figure 

2. The sizes of the squares used to symbolize CFS treatment 5 and LTEP treatments 

5a through d indicate that the average size of CFS treatment units is larger than that 

of LTEP treatment units. Because clearcuts cover all of the treatment area and have 

no residual overstory basal area, CFS treatment 5a and LTEP treatments 5a through 

d are shown as white squares in the upper left corner of figure 2. The control treatments for all LSSEs (100 percent residual overstory basal area and a matrix covering 100 percent of the total treatment area), in contrast, are shown as black squares 

clustered in the upper right corner of figure 2.

Each treatment-wide (or coarse-scale) spatial pattern is illustrated in figure 2 by 

the treatment matrix; for nonuniformly thinned stands, overstory removal gaps and 

patches of leave trees are shown by white and black dots, respectively. In general, 

the matrix as a percentage of total treatment area decreased as the overall complexity of the treatment-level spatial patterns increased. For example, DMS_IT treatment 3a in the lower right corner of figure 2 (x-axis value = 69 percent, y-axis value 
19

Large-Scale Silvicultural Experiments of Western Oregon and Washington

= 60 percent) is a moderate overstory removal treatment, with 10 percent of the 

treatment unit cut to create circular gaps of different sizes (0.25, 0.5, and 1.0 acres) 

and 10 percent of the treatment unit left uncut as circular, unthinned patches (0.25, 

0.5, and 1.0 acres). Portions of the variable-density thinnings at FES treatments 3a 

and b were designed to mimic openings caused by root rot (Carey et al. 1999b).

Not shown in figure 2 are additional (i.e., non-overstory) treatments such as 

planting to recruit understory cohorts. Underplanting in at least one treatment 

occurred at all but two LSSEs (DMS_RT and DMS_RB). The unthinned controls 

were underplanted at DMS_IT and STUDS. Additional treatments involving dead 

wood were implemented at LTEP and OHDS. At FES, additional treatments involve 

“den augmentation” either through the creation of nesting cavities or the installation 

of nest boxes to enhance populations of prey species.

Response variables measured at almost all of the LSSEs include over-, mid-, 

and understory vegetation, snags, woody debris, and the forest floor (matrix 6, table 

6). Arboreal mammals, soils, and economic variables were measured each at a different set of three LSSEs. Similarly, bats, climate, hydrology and geomorphology, 

forest pathology, and roads were measured at two different pairs of LSSEs. The 

only response variables measured at a single LSSE were large mammals (at OHDS) 

and fish (at DMS_RB).

Although many of the same general categories of variables were sampled at 

multiple sites, very few specific variables were sampled identically at multiple sites. 

For example, although bats were studied at both CFS and DEMO, canopy use by 

bats was sampled at CFS and bat abundance was sampled at DEMO. Given that 

most response variables were not sampled across multiple LSSEs, a formal metaanalysis involving data from multiple sites appears impossible for most response 

variables. Exceptions to this include ubiquitous tree-level response variables such 

as diameter growth. However, it is possible that future studies may be established 

across multiple LSSEs, thereby enabling the same response variables to be measured at a range of sites.

Discussion

Value of the Large-Scale Silviculture Experiments

First, the LSSEs have value because they reflect the issues that caused them to come 

about—clearcutting, old growth, and ecosystem management. As a group, these 

LSSEs have focused on developing silvicultural alternatives to clearcutting as a 

harvest and regeneration method. The LSSEs are developing new knowledge about 

innovative silvicultural treatments and systems and their applicability to meeting a 

variety of ecological, social, and economic objectives associated with sustainable 

The LSSEs have value 

because they reflect 

the issues that caused 

them to come about—

clearcutting, old 

growth, and ecosystem management.
20

GENERAL TECHNICAL REPORT PNW-GTR-713

forest management. For example, two-thirds of the LSSEs test silvicultural methods 

to accelerate the development of late-successional forest structure in young forests.

All of the LSSEs evaluate the effects of silvicultural treatments on a wide range 

of response variables, which include conventional variables such as tree growth and 

less conventional variables such as lichens, song birds, and social perceptions. The 

primary experimental factor is manipulation of the overstory through harvest and, 

in some cases, snag creation. Additionally, some understory manipulation, primarily release or respacing of regeneration, tree planting, or creation of downed coarse 

wood is also included as an experimental factor. The focus in young-growth studies 

has been on thinning to increase spatial heterogeneity, to increase understory light 

levels, to promote understory development, to enhance the rate of large-tree development, or to address other combinations of objectives.

From an ecosystem management perspective, the LSSEs address questions 

surrounding the use of active management to affect the sustainable production of 

diverse values or the restoration of ecological conditions and processes necessary 

to produce desired values from regional forest ecosystems. The LSSEs all measure 

a variety of response variables as indicators of ecological function derived from 

different forest structures. Ecological structures are the tangible components of an 

ecosystem and the way in which they are arranged spatially. For example, the snags 

in a stand are ecological structures that may be described in terms of number per 

acre, diameter, height, species, and decay class. An ecological process permitted by 

the presence of the snags is their use by birds for nesting.

Second, the LSSEs have value because they are silviculture experiments 

conducted at operational scales, both spatially and temporally. Most involved scientists have accepted that the LSSEs conform to generally agreed-upon standards 

of experimental design. The value of the LSSEs as long-term field experiments 

addressing the long-term response of forest ecosystems to silvicultural manipulations cannot be emphasized strongly enough (Franklin 1989, 2005; Tilman 1989). 

The operational nature of the LSSEs also includes economic and logistical feasibility, which are dependent on ownership, site, and objective. Various operational 

contexts have influenced the degree to which study design and layout conform to 

idealized concepts of experimentation as applied in an agronomic model, particularly with respect to uniformity or stratification of experimental units and treatment 

randomization. In reviewing these studies, it is clear that for each study, unique 

balances were struck among experimental design, operational criteria, and logistical or financial constraints.

Third, the LSSEs are valuable because of the generally high level of credibility 

they have as forest management research endeavors with scientists, managers, and 

The value of the 

LSSEs as long-term 

field experiments 

addressing the longterm response of 

forest ecosystems 

to silvicultural 

manipulations cannot 

be emphasized 

strongly enough.
21

Large-Scale Silvicultural Experiments of Western Oregon and Washington

stakeholders such as environmental groups. One source of this credibility stems 

from the fact that a majority of scientists, managers, and stakeholders recognize 

that the LSSEs seek to answer research questions important to them. Another 

source of credibility comes from the recognition that the LSSEs conform to many 

of the “real world” constraints perceived by different groups. For many managers, 

the LSSEs have a high degree of credibility because the LSSEs are perceived as 

operational in terms of scale, harvesting practices, and—in many cases—environmental constraints such as riparian buffers. Another source of LSSE credibility for 

scientists and managers is that, to varying degrees, both groups have been involved 

in the design and implementation of the LSSEs. The fact that peers are directly 

involved with the LSSEs very likely contributes to the credibility with which 

scientists and managers view the LSSEs.

One great value of the LSSEs is as demonstrations of alternative forest management practices. For example, managers who have toured established LSSEs are 

far more willing than they would otherwise be to try innovative approaches on the 

lands they manage. Managers are implementing silvicultural practices based on 

innovations being evaluated in LSSEs before the results of the studies are known 

(Monserud 2002). By demonstrating a wide range of silvicultural alternatives to 

clearcutting, the LSSEs may provide land managers with increased credibility 

among environmental groups or other stakeholders who may have rejected silvicultural treatments on the basis that they are synonymous with clearcutting.

An extremely valuable consequence of the credibility the LSSEs have with 

scientists, managers, and stakeholders is that the LSSEs represent a common forum 

within which various, sometimes disparate groups can cooperatively interact on 

forest management issues. Interactions in such a common forum are far more likely 

to promote constructive dialog between groups that might otherwise have only 

interacted in the courts (Wondolleck and Yaffee 2000).

Limitations of the Large-Scale Silviculture Experiments

The value of the LSSEs as long-term studies highlights one of their limitations—

the need to wait for long-term results. Because short-term responses of forest 

ecosystems to silvicultural treatments can be transient, initial results must be 

viewed with a degree of caution (Tilman 1989). The long-term nature of the LSSEs 

virtually guarantees that one or more of the treatment replicates at a given LSSE 

will be affected by some disturbance. For example, several treatment replicates at 

the southernmost LTEP installation were burned in the 2002 Biscuit Fire. It remains 

to be seen whether the loss of these treatment replicates will compromise the LTEP 

experimental design.

By demonstrating 

a wide range 

of silvicultural 

alternatives to 

clearcutting, the 

LSSEs may provide 

land managers with 

increased credibility 

among environmental 

groups or other 

stakeholders who 

may have rejected 

silvicultural treatments 

on the basis that they 

are synonymous with 

clearcutting.

The long-term nature 

of the LSSEs virtually 

guarantees that one or 

more of the treatment 

replicates at a given 

LSSE will be affected 

by some disturbance. 
22

GENERAL TECHNICAL REPORT PNW-GTR-713

Another limitation of the LSSEs is that it may be difficult to conduct a synthesis 

across LSSEs. To do so in a conventional meta-analysis requires identification of 

common currencies and a degree of commonality in experimental and sampling 

designs to meet statistical assumptions. Initial assessments would indicate that these 

requirements may not be well met across all of the LSSEs reviewed here. Overstory 

development probably holds the greatest potential for providing a common currency 

for cross-study synthesis but sampling schemes differ substantially among studies. 

For two Oregon studies, YSTDS and UAMP, the vegetation sampling schemes were 

designed very similarly; that of DMS is also fairly similar. These three studies are 

currently undergoing a synthetic assessment. Approaches that avoid some statistical 

assumptions may prove useful, although they are not as well known or understood 

by the scientific community. One such approach is Bayesian Belief Network, which 

is a methodology capable of incorporating data from a wide range of sources to 

develop correlation estimates among variables that permit prediction of the magnitude of response as well as the precision of the estimated response. Synthesis may 

also be based on models. Such models would be derived from response surfaces 

translated to empirical, process, or hybrid model structures. Typically, models 

developed to date address a narrow range of response parameters—most commonly 

vegetation and perhaps one to a few additional values.

The response variables being measured may be as much a reflection of the 

scientists involved as they are an underlying model of key regional indicators. This 

lack of strict common currency may limit potentials for meta-analysis, although it 

may also, in a coarse construct, permit identification of common trends in response 

to silvicultural treatments. Community-level responses may be more readily 

detectable than species-level responses. Recognizing this need, there is potential 

for future work to adopt common currencies for response. Two additional questions 

needing to be addressed are (1) what constitutes a pertinent response variable, and 

(2) are these variables likely to be consistent over time or will they change with 

changing issues and management paradigms?

Another limitation of the LSSEs is that—in some cases—participation by 

various disciplines has been tepid or waned over time. This may be due to varying 

levels of available funding or interested students; certainly, many LSSEs would 

have addressed more and varied questions had funding been available to do so.4

It also may be due to the different temporal and spatial scales at which various 

questions can be addressed. However, in some cases, it may be a failure of the 

4Wilson, T. 2006. Personal communication. Wildlife biologist, Forestry Sciences Laboratory, 

3625 93rd Ave. SW, Olympia, WA 98512.

Another limitation 

of the LSSEs is that 

it may be difficult to 

conduct a synthesis 

across LSSEs. 
23

Large-Scale Silvicultural Experiments of Western Oregon and Washington

“Field of Dreams“ (build it and they will come) premise. Whatever the reasons, 

levels of short- and long-term commitment to these large studies have been inconsistent among disciplines, programs, and institutions.

Role of Large-Scale Silviculture Experiments in 

Addressing Emerging Management Issues

Although there is an extensive body of literature describing silvicultural manipulation of stand structure, this work has focused predominantly on issues of stand 

development to maximize tree growth and yield. As such, the silvicultural systems 

often promoted uniform, early-seral, stand conditions and ignored structural 

elements necessary to meet habitat requirements for many late-successional organisms (Carey et al. 1999a). To achieve these objectives of heterogeneity requires new 

applications of evolving silvicultural principles and practices that result in definition of new silvicultural systems (Bailey and Tappeiner 1998, O’Hara 1998).

A commonality of the LSSEs is the use of silvicultural manipulation to enhance 

structural heterogeneity. Eventually an objective is to assess and understand the 

ways and extents to which alterations in structure result in changes in functionality. Examples of this include DMS_RB, which assesses the overstory structure 

influence on microclimate and associated consequences for amphibian habitats, 

and FES, which assesses the enhancement of spotted owl habitat through overstory 

manipulation and prey den enhancement. Structural objectives can be arrayed along 

a continuum from production of commercial wood products to development of latesuccessional/old-growth structure. Intermediate along the axis may be an objective 

to create midseral structures that support a combination of midseral species and 

high-quality wood production.

This group of studies is addressing several questions that have remained 

relevant over the 5 to 15 years since the studies were initiated. For example, under 

existing policy, federal lands designated as LSR have a capstone age beyond which 

harvest is tightly restricted. The question exists as to whether there are ecological 

objectives that would warrant active management, including density management, 

of LSR stands to a later age. Results from these LSSEs indicate that young (35- to 

60-year-old), west-side Douglas-fir stands respond to thinning with a relatively 

rapid closure of the overstory canopy and decreased rates of crown recession. The 

upper limit to age at which these stands can demonstrate such canopy and crown 

responses has not yet been determined. Additionally, there is emerging evidence 

that underplanting of thinned forests can accelerate development of a second 

cohort. The question remains as to whether understory tree regeneration can persist 

and develop connectivity with the overstory without additional thinning entries 

A commonality of 

the LSSEs is the 

use of silvicultural 

manipulation to 

enhance structural 

heterogeneity.
24

GENERAL TECHNICAL REPORT PNW-GTR-713

to maintain understory light levels sufficient for growth and development of tree 

regeneration. Furthermore, to what extent do thinning practices to enhance understory recruitment have concomitant benefits to development of a large snag and 

downed wood supply and understory vegetation as habitat?

The LSSEs reviewed have been designed as long-term studies. As such, they 

are a unique resource for addressing long-term issues. For example, as a collective, the studies here could be envisioned as a barometer for regional dynamics of 

climate change. As distributed, they constitute a latitudinal array that may prove 

useful to regional monitoring. Although research natural areas (RNAs) and other 

reserved lands may have similar potential, these LSSEs are unique in that they 

include active management and will potentially provide insight to the interactive 

effects of climate change stresses and silvicultural practices on the provision of 

ecological, social, and commodity values. Additionally, it is worth noting that the 

LSSEs have permanent plots and a data record, which is likely absent for many 

RNAs (see footnote 1).

As indicated throughout this report, the principal driver of forest management 

has shifted in the past several decades from timber production to a broad suite of 

ecological and social benefits in addition to timber-related commodities. Interestingly, many of the ecological benefits are recently being viewed as services to be 

valued in economic terms, not unlike timber production. As ecological benefits or 

services attain broadly recognized value, there will be increasing interest in the 

production of these values through active management. Therefore, these LSSEs are 

potentially well positioned to address the emerging interests in nontimber forest 

products, carbon sequestration, and other ecological values when the questions 

involve management through silvicultural manipulation.

In an April 2006 LSSE workshop, representatives of federal and state agencies’ regional and forest leadership identified fuels management, postfire salvage, 

invasive species, and implementation of adaptive management as priority issues. 

Fuels management, salvage, and invasive species are frequently associated with forest lands east of the Cascade Range. However, this does not mean that these LSSEs, 

located in the western portions of Washington and Oregon are irrelevant to fire and 

restoration issues. Although occurrence of fire is of lower historical frequency in 

the more mesic west-side forests, fire has had a substantial role in the development 

of the west-side Cascades and Coast Range forests. The regeneration following 

the vast Tillamook Fires in the mid-20th century exemplifies a vast area of young, 

even-aged forests within the range of the northern spotted owl for which structural 

heterogeneity is deemed inadequate and in need of restoration. Manipulation of 

young stand structure through thinning, as addressed in most of these LSSEs, is 

Although research 

natural areas and 

other reserved lands 

may have similar 

potential, LSSEs 

are unique in that 

they include active 

management. 
25

Large-Scale Silvicultural Experiments of Western Oregon and Washington

having corollary effects on fuel loading. The vegetation, snag, and down wood 

sampling being conducted in many of these studies can be readily translated into 

measures of fuel loading.

Invasive species have been identified by the Forest Service—along with fire 

and fuels, loss of open space, and unmanaged recreation—as one of the four threats 

facing the Nation’s grasslands and forests in the early 21st century (Bosworth 2004). 

As with fire and salvage, invasive species are receiving more attention in east-side 

forests than in west-side forests. However, forests throughout the west side of the 

region are heavily traveled, and development in low-elevation forests is accelerating, particularly near urban centers. Thus, the threat of invasive species spreading 

throughout the west side of the region is great. The establishment of an invasive 

species at an LSSE may prove to be the ideal opportunity to monitor ecosystem 

responses to that invasive species.

Similarly, the LSSEs can contribute to the process of adaptively managing 

forests. The premise of adaptive management is that incorporating experimentation 

into management accelerates the pace of learning and, consequently, of adapting 

forest management practices as needed. Adaptive management is an important element of ecosystem management, as it encompasses monitoring to validate assumptions and overall effectiveness in meeting management objectives. A key role of 

the LSSEs within the broader context of developing management alternatives is in 

identifying and characterizing important ecological relationships and discerning 

appropriate variables to measure (or monitor) in order to assess the functionality of 

those relationships. Thus, the LSSEs reviewed here have the potential to contribute 

greatly to the adaptive management process.

Conclusions

Although not directly addressing all management issues that may arise, these 

LSSEs address information needs having a long-term context, and they were 

implemented at scales directly relevant to management planning and decisionmaking. They are generally founded on strong collaboration between scientists 

and managers. As a result, they serve to increase technical knowledge and abilities 

to meet objectives, increase science relevance through direct interaction among 

scientists and managers in a real-world context, increase credibility for management 

activities, assist managers in positioning to meet future issues, and provide new 

knowledge. The immediate value of these studies extends beyond development of 

knowledge, as the research process provides important learning opportunities for 

the managers, scientists, policymakers, and members of the public engaged in 

the studies.
26

GENERAL TECHNICAL REPORT PNW-GTR-713

In our attempt to identify the management needs and science questions being 

addressed by these LSSEs, there was a consistent theme—evaluation of manipulation of forest structure on the delivery of a variety of ecological, social, or economic 

values. Specific contexts differ as objectives range from ecologically sound application of even-aged silvicultural systems with an emphasis on wood production, to 

enhanced development of late-successional forest structures and habitat. Some 

reframing of issues may be occurring, such as increased interest in midseral 

forest structures as a management target for matrix lands. The question remains 

as to whether or not enhanced structural diversity in young stands translates to 

late-successional functionality. The value of structural heterogeneity to ecological 

processes and functions is likely scale-dependent, but a better understanding of 

the interactions between stand and landscape sources of variation is needed. In 

general, there needs to be increased knowledge about the relationships among forest 

management, aquatic and riparian habitats, and watershed function. Although these 

studies are generally focused on state or federal lands, collectively they are relevant 

to the full range of forest ownerships present in the region. Whereas these studies 

address the biological and technical aspects of forest management, it is important 

to understand that the public perceptions of management issues may not match 

those of the science or management communities. Therefore, it is important that 

the underlying questions for each of these studies be carefully considered and 

articulated.

Several challenges exist for this group of studies. With decreasing resources 

region- and stationwide, it is important to develop needed information efficiently. 

There is a need for synthetic efforts to fully capitalize on the body of information 

being generated in these studies. Although the studies have some commonalities, 

there are relatively few values that were consistently quantified across all studies 

that would facilitate a conventional meta-analysis. Another challenge for the studies 

will be finding the appropriate balance between value as a learning opportunity 

and the need for statistical rigor. This balance will determine the ways in which the 

information generated and the research process can be useful. Funding will always 

be a challenge for these studies as a group. It is important to note, however, that the 

data collection and entry processes may be relatively inexpensive components of 

the studies once the initial establishment has occurred. Potential keys to collective 

success are to prioritize the information needs, identify where that information 

can be best obtained, and, as appropriate, build geographic and inferential scope 

across studies.

Those studies 

that appear well 

positioned for the 

long run typically 

have support 

throughout the 

hierarchical 

structures of 

the partnering 

institutions.
27

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Those studies that appear well positioned for the long run typically have 

support throughout the hierarchical structures of the partnering institutions. For 

example, DMS has developed an infrastructure consisting of a steering committee 

representing all partner institutions, a science liaison, and site coordinators representing each administrative unit on which study installations occur. The various 

management and science partners meet at least once per year to discuss logistics 

and to communicate progress and key findings. The DMS has held large workshops 

approximately biannually. Scientists participate with ID teams in addressing 

National Environmental Policy Act requirements for planned activities. The DMS 

scientists have provided briefings to BLM and PNW leadership teams. There is a 

strong effort at communicating the study in its various aspects to partnering and 

potential user groups.

Acknowledgments

We gratefully acknowledge the overall reviews of this report by John Cissel, Susan 

Hummel, and John Tappeiner. Helpful comments and suggestions were made at 

various points by numerous additional individuals, including (in alphabetical order) 

Richard Abbott, Keith Aubry, Bernard Bormann, Leslie Brodie, Lynn Burditt, Sam 

Chan, Robert Curtis, Robyn Darbyshire, Allan Derickson, William Emmingham, 

Jeffrey Foster, Cheryl Friesen, James Golden, Charles Halpern, Constance Harrington, Richard Haynes, Stuart Johnston, Margaret Kain, Craig Kintop, Mark 

Koski, Nancy Lankford, David Larson, Jose Linares, Sue Livingston, Kathleen 

Maas-Hebner, David Marshall, Jon Martin, Robert Monserud, Jon Nakae, Bob 

Obedzinski, Kathy O’Halloran, Deanna Olson, Peter O’Toole, James Perkins, 

Charles Peterson, Sharmila Premdas, Frank Price, Klaus Puettmann, Jewel Reid, 

Robert Ribe, Hugh Snook, Tom Spies, Frederick Swanson, Charles Thompson, Kim 

Titus, Stephanie Wessell, Duncan Wilson, and Todd Wilson. We greatly appreciate 

the dedicated efforts of Lynn Sullivan, Frank Vanni, Keith Routman, Tiffany Dong, 

and Jared Ranum in bringing this manuscript and companion Web site to fruition. 

We apologize if we have overlooked acknowledging anyone.
28

GENERAL TECHNICAL REPORT PNW-GTR-713

Metric Equivalents

When you know:	 Multiply by:	 To find:

Inches (in) 2.54 Centimeters

Feet (ft) 0.3048 Meters

Miles (mi) 1.609 Kilometers

Square feet (ft2) 0.0929 Square meters

Acres (ac) 0.405 Hectares

Trees per acre 2.471 Trees per hectare

Square feet per acre (ft2/ac) 0.229 Square meters per hectare

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33

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Initial Installation Years: 1998–2004 

Primary Objectives: Create onthe-ground examples of a number of 

contrasting silvicultural systems (i.e., 

a range of disturbances and levels 

of retention) 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 

contrasting systems over an extended 

period with procedures that will provide 

quantitative estimates of vegetation 

change and timber outputs, and statistically sound tests of 

differences between systems. 

Pretreatment Conditions: 40- to 70-year-old, even-aged 

Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands.

Locations: Blue Ridge (46.8500°N, 123.1500°W), 

Copper Ridge (47.0333°N, 123.0667°W), and Rusty 

Ridge (46.9500°N, 123.2000°W). 

Initial Treatments: 5 thinning treatments and 1 unthinned 

control each replicated 1 time at 3 locations. 

No Overstory Removal (Control)

Control (1a). Provide a comparison with gains obtainable 

by the repeated thinning regime when some stands are 

held on an extended rotation as a means of adjusting 

currently unbalanced age distributions and reducing 

visual impacts on the landscape. Not thinned. Not 

planted. No woody debris or other initial treatments. 

Light Overstory Removal

Repeated thinning (2a). Extended rotation with repeated, 

light, commercial thinnings. Thinned 100 percent of stand 

to a relative density (RD) of 40 to 50, where RD = basal 

area (ft2/ac) / square root of the quadratic mean diameter 

(in), the diameter of the tree of average basal area. Not 

planted. No woody debris or other initial treatments. 

Moderate Overstory Removal

Group selection (3a). Group selection uneven-age 

management, producing a unit consisting of five age 

classes on an approximately 50- to 75-year rotation. 

Thinned 80 percent of stand to RD 45 as needed. Cut 

20 percent of stand in groups ranging from individual 

trees to groups of trees not larger than 1.5 ac on a 10- to 

15-year cycle. Harvest groups dispersed throughout 

stand. Planted openings larger than 0.10 ac to Douglasfir. Control competing vegetation as needed. No woody 

debris or other initial treatments.

Patch cut (3b). Patch-wise uneven-age management, 

producing a unit consisting of five age classes on an 

approximately 50- to 75-year rotation. Thinned 80 

percent of stand to RD 45 as needed. Cut 20 percent of 

stand to create somewhat irregularly shaped 1.5- to 5.0-

ac patches on a 10- to 15-year cycle. Harvest patches 

dispersed throughout stand. Patches planted to Douglasfir and/or a mix of Douglas-fir and other species. Control 

competing vegetation as needed. No woody debris or 

other initial treatments. 

Heavy Overstory Removal

Two-age (4a). Reserve shelterwood resembling a 

conventional shelterwood but with the overwood, or 

a portion of it, carried through the second rotation to 

provide large-diameter trees and high-quality material. 

Thinned 100 percent of stand to 15 trees/ac, with leave 

trees selected for spacing, vigor, and stem quality. 

Underplanted Douglas-fir. Control competing vegetation 

as needed. No woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

Clearcut (5a). Provide a direct quantitative comparison 

of clearcut costs and outputs with those of the other 

regimes. Clearcut 100 percent of stand, except for 

scattered groups of leave trees as needed to meet 

Washington Department of Natural Resources (WADNR) 

rules. Plant according to current WADNR practices. 

Control competing vegetation as needed. No woody 

debris or other initial treatments.

Response Variables: Over-, mid-, and understory 

vegetation; lichens, mosses, and bryophytes; birds; 

snags; social perceptions; wood production; economics; 

operational factors; forest floor. 

Study Plan: Curtis, R.O.; Clendenen, G.W.; DeBell, D.S.; 

DeBell, J.; Shumway, J.; Poch, T. 2001 (revised; originally 

1997). Silvicultural options for harvesting young-growth 

production forests. Part I. The stand-level silvicultural 

experiment. Study plan (silviculture). On file with: R. Curtis, 

U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station, Forestry Sciences Laboratory, 

3625 93rd Avenue SW, Olympia, WA 98512. 

Web Site: http://www.fs.fed.us/pnw/olympia/silv/selectedstudies/blue-ridge/index.shtml (last accessed December 6, 

2006).

Appendix 1—Capital Forest Study (CFS)

CFS ")")")
34

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 2—Clearwater Study (CWS)

Initial Installation Years: 1994–1995

Primary Objectives: Evaluate shortand long-term growth and yield of 

overstory trees, stand differentiation, 

and variation in horizontal and vertical 

structure in response to alternative 

silvicultural prescriptions. Monitor 

short- and long-term population 

responses of small mammals, birds, 

amphibians, and vascular plants to 

the implementation of alternative 

silvicultural prescriptions. Accelerate 

the development of characteristics 

associated with late-successional 

forests.

Pretreatment Conditions: 10- to 13-year-old, evenaged Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) 

plantations.

Locations: Clearwater Study (CWS; 46.2560°N, 

121.9980°W) and Very Young Stand Management Study 

(VYSMS; 44.2528°N, 122.2064°W).

Initial Treatments: 4 thinning × planting treatments and 

1 unthinned control each replicated 5 times at the CWS 

location and each 1 time at the VYSMS location.

No Overstory Removal (Control)

Treatment A: untreated control (1a). Provide a 

comparison between rates of stand development 

and differentiation with and without postplanting 

treatments. Not thinned. Not planted. No woody 

debris or other initial treatments.

Light Overstory Removal

None.

Moderate Overstory Removal

Treatment B: thinned (no gaps), not planted (3a). 

Emphasize uniformity of species composition and stand 

structure with a long-term goal of high-value wood 

production. Thinned 100 percent of stand uniformly to 

340 trees/ac by removing alternate diagonal rows. Not 

planted. No woody debris or other initial treatments.

Heavy Overstory Removal

Treatment C: thinned (1 gap size), planted (4a). Increase 

tree species diversity without making major changes in 

uniformity of tree spacing. Thinned 100 percent of stand 

uniformly to 340 trees/ac by removing alternate diagonal 

rows. Removed additional 100 trees/ac to create eight 

uniformly distributed 42- × 42-ft (0.04 ac) gaps per acre. 

Planted with 100 trees/ac red alder (Alnus rubra Bong.) 

in gap centers. Planted 40 trees/ac western hemlock 

(Tsuga heterophylla [Raf.] Sarg.) and 40 trees/ac western 

redcedar (Thuja plicata Donn ex D. Don) on the gap 

edges. Planting was not as uniform as the treatment 

descriptions imply. No woody debris or other initial 

treatments.

Treatment D: thinned (3 gap sizes), not planted (4b). 

Increase structural heterogeneity. Treatment is designed 

to increase horizontal and vertical diversity (spatial 

heterogeneity) in the stand. Thinned 100 percent of stand 

uniformly to 340 trees/ac by removing alternate diagonal 

rows. Removed additional 100 trees/ac to create three 

different-sized gaps: 16 × 28 ft, 28 × 42 ft, and 42 × 42 ft. 

Not planted. No woody debris or other initial treatments.

Treatment E: thinned (3 gap sizes), planted (4c). Increase 

species, vertical and horizontal diversity. Treatment is 

an attempt to accelerate the development of conditions 

associated with old-growth forests through intensive 

silviculture. Thinned 100 percent of stand uniformly 

to 340 trees/ac by removing alternate diagonal rows. 

Removed additional 100 trees/ac to create three 

different-sized gaps: 16 × 28 ft, 28 × 42 ft, and 42 

× 42 ft. Selected 30 large and vigorous trees/ac for 

growth enhancement. Kept 20 trees/ac of the growth 

enhancement trees in an open-grown situation to 

maximize growth. Planted 50 trees/ac red alder (7- ×

7-ft spacing) in 28- × 41-ft and 41- × 41-ft gaps. Planted 

75 trees/ac western hemlock and 75 trees/ac western 

redcedar (6 × 6 ft) in gaps of all three sizes. Planting was 

not as uniform as the treatment descriptions imply. No 

woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; mosses; snags; woody debris; climate; wood 

production; economics; forest floor.

Study Plan: Crisafulli, C.M.; Harrington, C.A. 1994. 

Alternative silviculture in young Douglas-fir plantations: 

effects of stand composition and structure on plant and 

animal populations and on the production of forest products. 

Study plan. On file with: C. Harrington, U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Research 

Station, Forestry Sciences Laboratory, 3625 93rd Avenue 

SW, Olympia, WA 98512.

Web Site: http://www.fs.fed.us/pnw/olympia/silv/selectedstudies/clearwater/ (last accessed December 6, 2006).

")

")

CWS
35

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Appendix 3—Demonstration of Ecosystem Management Options Study 

(DEMO)

Initial Installation Years: 1994–1995 

Primary Objectives: Determine 

how the level of retention following 

overstory removal influences biological 

values and social perceptions of 

mature, coniferous forests. Determine 

whether, for a particular level of 

retention, spatial pattern of retention 

is important. Determine whether a 15 

percent level of retention is sufficient to 

maintain the organisms and processes 

that characterize late-seral forests 

in the Pacific Northwest. Determine 

which species or groups of organisms 

are most sensitive to variation in the amount or spatial 

pattern of retention. 

Pretreatment Conditions: 65- to 170-year-old stands 

dominated by Douglas-fir (Pseudotsuga menziesii [Mirb.] 

Franco).

Locations: Butte (46.3720°N, 121.5920°W), Capitol 

Forest (46.8880°N, 123.1230°W), Dog Prairie (43.1960°N, 

122.3060°W), Little White Salmon (45.8580°N, 

121.7020°W), Paradise Hills (46.0030°N, 122.0430°W), 

and Watson Falls (43.2620°N, 122.2460°W). 

Initial Treatments: 5 overstory removal treatments and 

1 unthinned control each replicated 1 time at 6 locations. 

No Overstory Removal (Control)

100-percent retention (1a). Provide untreated control. Not 

thinned. Not planted. No woody debris or other 

initial treatments. 

Light Overstory Removal

75-percent aggregated retention (2a). High retention 

in aggregated fashion. Three circular 2.47-ac (1-ha) 

patches harvested in an evenly spaced triangular array 

removing 25 percent of the stand basal area. Created 2.6 

snags/ac in harvested areas from dominant/co-dominant 

trees. Planted ~165 to 300 trees/ac to achieve minimum 

stocking; planting mix composed of 2 to 5 species that 

differed by geographic location. No additional woody 

debris or other initial treatments. 

Moderate Overstory Removal

40-percent aggregated retention (3a). Moderate retention 

in aggregated fashion. Five undisturbed 2.47-ac (1-ha) 

circular patches retained evenly spaced within the 

harvest unit. Planting and snag treatments identical 

to treatment 2a. No additional woody debris or other 

initial treatments.

40-percent dispersed retention (3b). Moderate 

retention in dispersed fashion. Dominant and codominant trees retained in an even distribution 

throughout the treatment unit; total basal area 

equivalent to that retained in treatment 3a. Planting 

and snag treatments identical to treatment 2a. No 

additional woody debris or other initial treatments. 

Heavy Overstory Removal

15-percent aggregated retention (4a). Low retention 

(Northwest Forest Plan [NWFP] minimum) in aggregated 

fashion. Two undisturbed 2.47-ac (1-ha) circular patches 

retained at diagonally opposite positions within the 

harvest unit. Planting and snag treatments identical to 

treatment 2a. No additional woody debris or other initial 

treatments.

15-percent dispersed retention (4b). Low retention 

(NWFP minimum) in dispersed fashion. Dominant and 

co-dominant trees retained in an even distribution 

throughout the treatment unit; total basal area equivalent 

to that retained in treatment 4a. Planting and snag 

treatments identical to treatment 2a. No additional 

woody debris or other initial treatments. 

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; lichens and bryophytes; arboreal mammals; 

small mammals; bats; birds; arthropods; amphibians; 

mollusks; woody debris; fungi; microclimate; hydrology; 

social perceptions; forest floor. 

Study Plan: Anonymous. 1996. Demonstration of 

Ecosystem Management Options: a study of green-tree 

retention levels and patterns in western Oregon and 

Washington. Unpublished study plan. On file with: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest 

Research Station, Forestry Sciences Laboratory, 620 SW 

Main Street, Suite 400, Portland, OR 97205. 

Web Site: http://www.cfr.washington.edu/research.demo/ 

(last accessed December 6, 2006).

DEMO

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36

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 4—Density Management Study, Initial Thinning (DMS_IT)

DMS_IT ")

")

") ")

")

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Initial Installation Years: 1996–2000 

Primary Objectives: Evaluate 

effects of alternative forest density 

management treatments on important 

stand and habitat attributes in 

previously unthinned stands. 

Determine treatment effects on 

selected plant and animal taxa. Use 

these sites to develop operational 

approaches to implementation of 

new prescriptions, improve methods 

for effectiveness monitoring of plant 

and animal taxa, and share results of 

on-the-ground practices and findings 

with land managers, regulatory agencies, policymakers, and 

the public. 

Pretreatment Conditions: 50- to 70-year-old stands 

dominated by Douglas-fir (Pseudotsuga menziesii [Mirb.] 

Franco).

Locations: Bottom Line (43.7722°N, 123.2364°W), Delph 

Creek (45.2656°N, 122.1592°W), Green Peak (44.3667°N, 

123.4583°W), Keel Mountain (44.5281°N, 122.6319°W), 

North Soup (43.5658°N, 123.7772°W), OM Hubbard 

(43.2916°N, 123.5833°W), and Ten High (44.2806°N, 

123.5183°W). 

Initial Treatments: 3 thinning treatments and 1 unthinned 

control each replicated 1 time at 7 locations. 

No Overstory Removal (Control)

Unthinned control (1a). Not thinned. Underplanted nine 1-

ac areas with western hemlock (Tsuga heterophylla [Raf.] 

Sarg.) and western redcedar (Thuja plicata Donn ex D. 

Don). No woody debris or other initial treatments. 

Light Overstory Removal

High-density retention (2a). Thinned 70 to 75 percent 

of stand to 120 trees/ac. Left 20 to 30 percent of stand 

as riparian buffers and/or leave islands of three sizes 

(0.25, 0.5, and 1.0 ac). Underplanted nine 1-ac areas with 

western hemlock and western redcedar. No woody debris 

or other initial treatments. 

Moderate Overstory Removal

Moderate-density retention (3a). Thinned 60 to 65 

percent of stand to 80 trees/ac. Cut 10 percent of stand 

to create circular gaps (0.25, 0.5, and 1.0 ac). Left 10 

percent of stand in circular leave islands (0.25, 0.5, 

and 1.0 ac). Left 15 to 20 percent of stand as unthinned 

riparian buffers. Underplanted nine 1-ac areas with 

western hemlock and western redcedar. Planted gaps 

with western hemlock, Douglas-fir, western redcedar, and 

grand fir (Abies grandis [Dougl. ex D. Don.] Lindl.). No 

woody debris or other initial treatments.

Variable-density retention (3b). Thinned 10 percent of 

stand to 40 trees/ac, thinned 25 to 30 percent of stand 

to 80 trees/ac. Thinned 25 to 30 percent of stand to 120 

trees/ac. Cut 10 percent of stand to create circular gaps 

(0.25, 0.5, and 1.0 ac). Left 10 percent of stand in circular 

leave islands (0.25, 0.5, and 1.0 ac). Left 15 to 20 percent 

of stand as unthinned riparian buffers. Planted gaps and 

underplanted 40 trees/ac overstory areas with western 

hemlock, Douglas-fir, western redcedar, and grand fir. 

No woody debris or other initial treatments. 

Heavy Overstory Removal

None. 

Complete Overstory Removal (Clearcut)

None. 

Response Variables: Over-, mid-, and understory 

vegetation; lichens, mosses, and bryophytes; birds; 

arthropods; amphibians; mollusks; snags; woody debris; 

fungi; microclimate; forest floor.

Study Plan: Cissel, J.H.; Anderson, P.D.; Berryman, S.; 

Chan, S.S.; Olson, D.H.; Puettmann, K.J.; Thompson, 

C. 2006. BLM Density Management and Riparian Buffer 

Study: establishment report and study plan. Scientific 

Investigations Report 2006–5087. Reston, VA: U.S. 

Department of the Interior, Geological Survey. 144 p. 

Web Site: http://ocid.nacse.org/nbii/density/ (last accessed 

December 6, 2006).
37

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Appendix 5—Density Management Study, Rethinning (DMS_RT)

Initial Installation Years: 1996–2007

Primary Objectives: Evaluate 

effects of alternative forest density 

management treatments on important 

stand and habitat attributes in stands 

thinned 25 to 30 years earlier to >100 

trees/ac. Determine treatment effects 

on selected plant and animal taxa. 

Use these sites to develop operational 

approaches to implementation of new 

prescriptions, improve methods for 

effectiveness monitoring of plant and 

animal taxa, and to share results of 

on-the-ground practices and findings 

with land managers, regulatory agencies, policymakers, 

and the public.

Pretreatment Conditions: 60- to 90-year-old stands 

dominated by Douglas-fir (Pseudotsuga menziesii [Mirb.] 

Franco).

Locations: Blue Retro (43.2803°N, 124.0825°W), Little 

Wolf (43.4222°N, 123.6292°W), North Ward (43.7689°N, 

123.2014°W), Perkins Creek (43.7142°N, 122.9131°W), and 

Sand Creek (44.8347°N, 123.5906°W).

Initial Treatments: 1 thinning treatment and 1 unthinned 

control each replicated 1 time at 5 locations.

No Overstory Removal (Control)

Unthinned control (1a). 25 to 30 years prior to initial 

DMS_RT treatments, overstory density reduced to >100 

trees/ac in a single commercial thinning. Initial DMS_RT 

treatment: not thinned. Not planted. No woody debris or 

other initial treatments.

Light Overstory Removal

None.

Moderate Overstory Removal

Re-thin (3a). 25 to 30 years prior to initial DMS_RT 

treatments, overstory density reduced to >100 trees/ac 

in a single commercial thinning. Initial DMS_RT thinning: 

thinned 100 percent of stand to a clumpy distribution of 

40 to 60 trees/ac. Not planted. No woody debris or other 

initial treatments.

Heavy Overstory Removal

None.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; snags; woody debris; forest floor.

Study Plan: Cissel, J.H.; Anderson, P.D.; Berryman, S.; 

Chan, S.S.; Olson, D.H.; Puettmann, K.J.; Thompson, 

C. 2006. BLM Density Management and Riparian Buffer 

Study: establishment report and study plan. Scientific 

Investigations Report 2006–5087. Reston, VA: U.S. 

Department of the Interior, Geological Survey. 144 p.

Web Site: http://ocid.nacse.org/nbii/density/ (last accessed 

December 6, 2006).

DMS_RT

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38

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 6—Density Management Study, Riparian Buffer (DMS_RB)

Initial Installation Years: 1996–2001

Primary Objectives: Characterize 

stream habitats and aquatic-dependent 

vertebrate diversity patterns in 

headwater stream networks. Examine 

effects of headwater aquatic vertebrate 

assemblages and their habitats of 

different riparian buffer widths within 

early successional forests subject to 

upslope timber thinning experiments; 

examine these findings in light of study 

of streamside-to-upslope vegetation, 

microhabitat, and microclimate 

regimes. Evaluate microclimate, 

microsite, and light responses to upland density 

management treatments and different riparian buffers.

Pretreatment Conditions: 50- to 90-year-old stands 

dominated by Douglas-fir (Pseudotsuga menziesii [Mirb.] 

Franco).

Locations: Bottom Line (43.7722°N, 123.2364°W), 

Callahan Creek (43.8347°N, 123.5906°W), Cougar 

(44.5117°N, 123.6636°W), Delph Creek (45.2656°N, 

122.1592°W), Grant (44.5117°N, 123.7642°W), Green Peak 

(44.3667°N, 123.4583°W), Keel Mountain (44.5281°N, 

122.6319°W), North Soup (43.5658°N, 123.7772°W), North 

Ward (43.7689°N, 123.2014°W), OM Hubbard (43.2916°N, 

123.5833°W), Perkins Creek (43.7142°N, 122.9131°W), 

Schooner (44.9358°N, 123.8558°W), and Ten High 

(44.2806°N, 123.5183°W).

Initial Treatments: 4 buffer width treatments and 1 

unthinned control each replicated once at some of 13 

locations.

No Overstory Removal (Control)

Unthinned control (1a). Provide baseline characteristics. 

Provide maximum buffer capacity for bank stability, 

coarse wood recruitment, and microclimate moderation; 

no environmental challenge. Not thinned. Riparian areas 

not planted. No woody debris or other initial treatments.

Light Overstory Removal

Two site-potential tree heights buffer (2a). Provide 

high buffer capacity for bank stability, coarse wood 

recruitment, and microclimate moderation; low 

environmental challenge. Overstory thinned or clearcut 

upslope of unthinned buffer ~480 ft wide, measured as 

slope distance from stream. Riparian areas not planted. 

No woody debris or other initial treatments.

Moderate Overstory Removal

One site-potential tree height buffer (3a). Provide 

high buffer capacity for bank stability, coarse wood 

recruitment, and microclimate moderation; moderate 

environmental challenge. Overstory thinned or clearcut 

upslope of unthinned buffer ~240 ft wide, measured as 

slope distance from stream. Riparian areas not planted. 

No woody debris or other initial treatments.

Heavy Overstory Removal

Variable-break buffer (4a). Provide moderate buffer 

capacity for bank stability, coarse wood recruitment, and 

microclimate moderation; high environmental challenge. 

Overstory thinned or clearcut upslope of unthinned 

buffer of variable width, determined by onsite streamside 

ecological breaks in vegetation and slope character. 

Minimum buffer 50 ft wide, measured as slope distance 

from stream. Riparian areas not planted. No woody 

debris or other initial treatments.

Streamside-retention buffer (4b). Provide moderate buffer 

capacity for bank stability, coarse wood recruitment, and 

microclimate moderation; high environmental challenge. 

Overstory thinned or clearcut upslope of unthinned buffer 

of variable width, determined by trees that directly confer 

both streambank stability by their rooting position next to 

streams and overhead shading by their crowns extending 

over the channel. Buffer width generally defined by trees 

within 20 ft of the channel. Riparian areas not planted. 

No woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; lichens, mosses, and bryophytes; arthropods; 

amphibians; fish; mollusks; snags; woody debris; fungi; 

microclimate; hydrology; forest floor.

Study Plan: Cissel, J.H.; Anderson, P.D.; Berryman, S.; 

Chan, S.S.; Olson, D.H.; Puettmann, K.J.; Thompson, 

C. 2006. BLM Density Management and Riparian Buffer 

Study: establishment report and study plan. Scientific 

Investigations Report 2006–5087. Reston, VA: U.S. 

Department of the Interior, Geological Survey. 144 p.

Web Site: http://ocid.nacse.org/nbii/density/ (last accessed 

December 6, 2006).

DMS_RB

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Large-Scale Silvicultural Experiments of Western Oregon and Washington

Appendix 7—Forest Ecosystem Study (FES)

Initial Installation Years: 1991–1993

Primary Objectives: Determine if 

woody plant species diversity, spatial 

heterogeneity in vegetation, and 

vertical diversity in vegetation can be 

manipulated through variable-density 

thinning and underplanting that do not 

require replacing the existing stand. 

Determine if enhancing the growth 

and diversity of woody plants will be 

accompanied by increased abundance 

and diversity of ectomycorrhizal fungi. 

Determine if increasing den availability 

through direct intervention (creating 

cavities in live trees and adding nest boxes) will increase 

flying squirrel populations.

Pretreatment Conditions: 55- to 65-year-old, even-aged 

Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands.

Locations: Fort Lewis (46.9900°N, 122.6900°W).

Initial Treatments: 2 thinning × den augmentation 

treatments and 2 unthinned control × den augmentation 

treatments each replicated 4 times at 1 location.

No Overstory Removal (Control)

Control, no den augmentation (1a). Not thinned. Not 

planted. No den augmentation. No woody debris or other 

initial treatments.

Control, den augmentation (1b). Identical to treatment 

1a but with den augmentation (i.e., nest boxes installed 

and/or cavities created).

Light Overstory Removal

None.

Moderate Overstory Removal

Variable-density thinning, no den augmentation (3a). 

Root-rot thinning applied to ~15 percent of stand: 

low-vigor trees removed and apparently healthy trees 

retained, producing residual densities of ~16 trees/ac >7.9 

in diameter at breast height (d.b.h.). Light thinning applied 

to 50 to 60 percent of stand: thinning of subordinate and 

codominant trees > 7.9 in d.b.h. to reduce the density of 

overstory to ~125 trees/ac with an average spacing of 

~19 ft between trees. Heavy thinning applied to 25 to 30 

percent of stand: thinning of subordinate and codominant 

trees > 7.9 in d.b.h. to reduce the density of overstory to 

~75 trees/ac with an average spacing of ~24 ft between 

trees. Marking guidelines specified retention of all large 

standing dead trees and all deciduous trees. Not planted. 

No den augmentation. No woody debris or other initial 

treatments.

Variable-density thinning, den augmentation (3b). 

Identical to treatment 3a but with den augmentation (i.e., 

nest boxes installed and/or cavities created).

Heavy Overstory Removal

None.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; arboreal mammals; small mammals; birds; 

arthropods; amphibians; snags; woody debris; fungi; soils; 

microclimate; forest pathology; roads.

Study Plan: Carey, A.B.; Thysell, D.R.; Brodie, A.W. 1999. 

The Forest Ecosystem Study: background, rationale, 

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.

Web Site: http://www.fs.fed.us/pnw/pubs/gtr_457.pdf (last 

accessed December 6, 2006).

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FES
40

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 8—Long-Term Ecosystem Productivity Study (LTEP)

Initial Installation Years: 1996–1998

Primary Objectives: Determine how 

potential and realized productivity are 

affected by the pathway along which 

succession is directed by management 

practices. Determine how altering the 

amount of periodic inputs of organic 

matter to the forest floor can influence 

long-term ecosystem productivity. 

Determine effects of underburning on 

the late-seral treatment.

Pretreatment Conditions: 70- to 100-

year-old, even-aged stands dominated 

by Douglas-fir (Pseudotsuga menziesii

[Mirb.] Franco).

Locations: Hebo (45.2167°N, 123.7500°W), Isolation 

(44.0667°N, 122.4000°W), Sappho (48.0667°N, 

124.2500°W), and Siskiyous (42.3333°N, 124.1667°W).

Initial Treatments: 1 thinning treatment, 2 clearcutting 

treatments, and 1 unthinned control each replicated 3 or 

4 times at 4 locations.

No Overstory Removal (Control)

Control (1a). Not thinned. Not planted. No organic matter 

removal. No other initial treatments.

Light Overstory Removal

None.

Moderate Overstory Removal

Late-successional, organic matter retention (3a). Initial 

thinning to move stands into understory re-initiation 

phase. Thinned 100 percent of stand to ~80 trees/ac. 

Underplanted ~150 trees/ac shade-tolerant conifers 

(e.g., western hemlock [Tsuga heterophylla {Raf.} Sarg.], 

western redcedar [Thuja plicata Donn ex D. Don], 

Pacific yew [Taxus brevifolia Nutt.], sugar pine [Pinus 

lambertiana Dougl.]). Organic matter retained. No other 

initial treatments.

Late-successional, organic matter removal (3b). Identical 

to treatment 3a, but with organic matter removed.

Heavy Overstory Removal

None.

Complete Overstory Removal (Clearcut)

Early-successional, organic matter retention (5a). Reinitiate stand development with a stand that emphasizes 

early seral species for up to two-thirds of the rotation. 

Clearcut 100 percent of stand. Planted ~150 to 200 

trees/ac of Douglas-fir and ~50 trees/ac of hardwoods 

(e.g., red alder [Alnus rubra Bong.], bigleaf maple [Acer 

macrophyllum Pursh]). Organic matter retained. No other 

initial treatments.

Early-successional, organic matter removal (5b). Identical 

to treatment 5a, but with organic matter removed.

Mid-successional, organic matter retention (5c). Reinitiate stand development with a stand that emphasizes 

Douglas-fir bole growth. Clearcut 100 percent of stand. 

Planted ~600 to 800 trees/ac of Douglas-fir. Organic 

matter retained. No other initial treatments.

Mid-successional, organic matter removal (5d). Identical 

to treatment 5c, but with organic matter removed.

Response Variables: Over-, mid-, and understory 

vegetation; lichens; small mammals; birds; reptiles and 

amphibians; snags; woody debris; fungi; soils; climate; 

forest pathology; social perceptions; wood production; 

forest floor.

Study Plan: Little, S.; Bormann, B.; Bednar, L.; Wurtz, 

T.; Zasada, J.; McClellan, M.; Shainsky, L.; Boyle, J.; 

Castellano, M.; Amaranthus, M.; Harrington, C.; Zabowski, 

D.; Geist, M. 2000. Long-Term Ecosystem Productivity 

(LTEP) program governing research plan for the integrated 

research sites. On file with: B. Bormann, U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Research 

Station, Forestry Sciences Laboratory, 3200 SW Jefferson 

Way, Corvallis, OR 97331.

Web Site: http://www.fsl.orst.edu/ltep/ (last accessed 

December 6, 2006).

LTEP

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Large-Scale Silvicultural Experiments of Western Oregon and Washington

Appendix 9—Olympic Habitat Development Study (OHDS)

Initial Installation Years: 1997–2006

Primary Objectives: Test management alternatives for their ability 

to accelerate development of 

characteristics associated with 

older stands. Test if accelerated 

development of the structures that 

are missing in the younger stands 

will increase the function of the 

ecosystem as habitat for forest-floordwelling terrestrial amphibians and 

small mammals.

Pretreatment Conditions: 35- to 62-year-old, even-aged 

stands dominated by Douglas-fir (Pseudotsuga menziesii

[Mirb.] Franco).

Locations: Bait (47.3900°N, 123.9100°W), Clavicle 

(48.0400°N, 124.2100°W), Eats (47.5700°N, 124.0400°W), 

Fresca (48.0500°N, 124.2900°W), North Fork Fulton 

(47.6500°N, 123.0000°W), Rail (48.0600°N, 124.0700°W), 

Snow White (47.9300°N, 122.9700°W), and Triton 

(47.6200°N, 123.0100°W).

Initial Treatments: 4 thinning × planting × coarse woody 

debris (CWD) treatments and 1 unthinned control each 

replicated 1 time at 8 locations.

No Overstory Removal (Control)

Control (1a). Not thinned. Not planted. No woody 

debris or other initial treatments.

Light Overstory Removal

None.

Moderate Overstory Removal

Variable-density thinning, not planted, coarse woody 

debris (CWD) clumped, slash dispersed (3a). Thinned 

75 percent of stand to 75 percent of pretreatment basal 

area. Cut 15 percent of stand to create small gaps. 

Left 10 percent of stand as uncut patches (“skips”). Not 

planted. CWD clumped and slash dispersed. No other 

initial treatments.

Variable-density thinning, not planted, CWD dispersed, 

slash dispersed (3b). Identical to treatment 3a, but with 

CWD dispersed and slash dispersed.

Variable-density thinning, planted, CWD clumped, 

slash clumped (3c). Identical to treatment 3a, but 

native understory species planted or seeded in 

existing or newly created openings and with CWD 

clumped and slash clumped.

Variable-density thinning, not planted, CWD removed, 

slash dispersed (3d). Identical to treatment 3a, but 

with CWD removed and slash dispersed.

Heavy Overstory Removal

None.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory vegetation; mosses; large, arboreal, and small mammals; bats; 

arthropods; amphibians; mollusks; snags; woody debris; 

fungi; microclimate; wood production; operational factors; 

roads; forest floor.

Study Plan: Harrington, C.A.; Carey, A.B. 1997. The 

Olympic Habitat Development Study conceptual study 

plan. On file with: C. Harrington, U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research 

Station, Forestry Sciences Laboratory, 3625 93rd Avenue 

SW, Olympia, WA 98512.

Web Site: http://www.fs.fed.us/r6/olympic/ecomgt/research/

habitat.htm (last accessed December 6, 2006).

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42

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 10—Siuslaw Thinning and Underplanting for Diversity Study 

(STUDS)

Initial Installation Years: 1992–1993

Primary Objectives: Characterize 

the effects of thinning to increase 

structural heterogeneity and 

underplanting on stand composition, 

structure, vegetative diversity, and 

productivity in young, even-aged 

Douglas-fir (Pseudotsuga menziesii

[Mirb.] Franco) stands of high site index 

in the Oregon Coast Range.

Pretreatment Conditions: 30- to 

33-year-old, even-aged, Douglas-fir 

plantations.

Locations: Cataract (44.0700°N, 123.9500°W), Wildcat 

(45.2000°N, 123.7800°W), and Yachats (44.2800°N, 

123.9400°W).

Initial Treatments: 3 thinning treatments and 1 unthinned 

control each replicated 1 time at 3 locations. All thinned 

treatments and unthinned control were underplanted with 

a 1:1 mix of Douglas-fir and western hemlock (Tsuga 

heterophylla [Raf.] Sarg.) at 10- × 10-ft spacing with root rot 

pockets planted to red alder (Alnus rubra Bong.). Imbedded 

within each overstory treatment were three underplanting 

trials. First, two 1-ac areas within each treatment unit were 

either underplanted with Douglas-fir and western hemlock at 

15 x 15 ft (species alternating within rows), or left unplanted. 

In a second conifer species trial, a single subplot per unit 

was planted with Douglas-fir, grand fir (Abies grandis

[Dougl. ex D. Don.] Lindl.), western redcedar (Thuja plicata

Donn ex D. Don), western hemlock, Sitka spruce (Picea 

sitchensis [Bong.] Carr.), and Pacific yew (Taxus brevifolia

Nutt.]). Each conifer species was planted at a 4.9- × 4.9-ft 

spacing in 13 four-seedling clusters arranged as a 6 × 13 

grid of randomly selected clusters, for a total of 52 seedlings 

of each species. A third planting trial consisted of red alder 

and bigleaf maple planted in alternate species rows of 16 

seedlings at 7.9- × 7.9-ft spacing. A total of 48 seedlings of 

each hardwood species were planted on each treatment 

at each site. Conifer planting occurred the winter after the 

block was thinned; hardwood planting occurred in the winter 

of 1994 at all three sites.

No Overstory Removal (Control)

No thin (1a). Passive management. Provide internal 

reference. Not thinned. Underplanted (see above). No 

woody debris or other initial treatments.

Light Overstory Removal

Narrow thin (2a). Grow large overstory trees, create 

understory-midstory cohorts, recruit coarse wood. Threestep overstory reduction to minimum density, repeated 

release of underplanted trees and natural regeneration. 

Thinned 100 percent of stand to ~100 trees/ac. 

Underplanted (see above). Slash cut to facilitate 15- ×

15-ft planting. No woody debris or other initial treatments.

Moderate Overstory Removal

Wide thin (3a). Grow large overstory trees, create 

understory-midstory cohorts, recruit coarse wood. 

Two-step overstory reduction to minimum density, single 

release of underplanted trees and natural regeneration. 

Thinned 100 percent of stand to ~60 trees/ac. 

Underplanted (see above). Slash cut to facilitate 15- ×

15-ft planting. No woody debris or other initial treatments.

Heavy Overstory Removal

Very wide thin (4a). Grow large overstory trees, create 

understory-midstory cohorts, recruit coarse wood. 

One-step overstory reduction to minimum density, single 

release of underplanted trees and natural regeneration. 

Thinned 100 percent of stand to ~30 trees/ac. 

Underplanted (see above). Slash cut to facilitate 15- ×

15-ft planting. No woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; mosses; snags; woody debris; microclimate; 

wood production; economics; operational factors; forest 

floor.

Study Plan: Tucker, G.F.; Emmingham, W.H.; Johnston, 

S.; Chan, S.S.; Minore, D.; Owston, P.; McCreight, R.W.; 

Hayes, J.P. 1993. Commercial thinning and underplanting 

to enhance structural diversity of young Douglas-fir stands 

in the Oregon Coast Range. Adaptive COPE study plan. 

On file with: P. Anderson, U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station, 

Forestry Sciences Laboratory, 3200 SW Jefferson Way, 

Corvallis, OR 97331.

Web Site: None.

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43

Large-Scale Silvicultural Experiments of Western Oregon and Washington

Appendix 11—Uneven-Aged Management Project (UAMP)

Initial Installation Years: 1997–2000

Primary Objectives: Determine the 

ecological and economic tradeoffs 

involved in converting young Douglasfir (Pseudotsuga menziesii [Mirb.] 

Franco) plantations at mid-elevation 

in the central Oregon Cascades to 

a mixed-species and uneven-aged 

condition.

Pretreatment Conditions: 35- to 

47-year-old, even-aged, Douglas-fir 

plantations.

Locations: H.J. Andrews 

Experimental Forest (44.2192°N, 

122.2042°W).

Initial Treatments: 3 thinning treatments and 1 unthinned 

control each replicated 4 times at 1 location.

No Overstory Removal (Control)

Control (1a). Passive management. Provide internal 

reference. Not thinned. Not planted. No woody debris or 

other initial treatments.

Light Overstory Removal

Single-tree selection (2a). Repeated light commercial 

thinning to residual stocking levels creating understory 

light sufficient for establishment and recruitment of 

naturally regenerated shade-tolerant tree species, along 

with planted shade-intolerant tree species. With repeated 

entries, stands will ultimately consist of ~10 cohorts 

dominated by shade-intolerant species. Thinned 100 

percent of stand from below to a relative density (RD) 

of 30, where RD = basal area (ft2/ac) / square root of 

the quadratic mean diameter (in), the diameter of the 

tree of average basal area. Underplanted stand with an 

even mixture of Douglas-fir, western hemlock (Tsuga 

heterophylla [Raf.] Sarg.), western white pine (Pinus 

monticola Dougl. ex D. Don), and western redcedar 

(Thuja plicata Donn ex D. Don) at a 10- × 10-ft spacing. 

No woody debris or other initial treatments.

Group selection (2b). Repeated light commercial thinning 

combined with gap creation to favor recruitment by 

shade-intolerant tree species. Final stand consisting 

of ~10 cohorts, dominated by Douglas-fir. Thinned 90 

percent of stand from below to RD 30. Cut 10 percent of 

stand to create circular gaps one tree height in diameter 

(~80 ft at initial treatment). Planted gaps with an even 

mixture of Douglas-fir, western hemlock, western white 

pine, and western redcedar at an 8- × 8-ft spacing (only 

gaps were planted). No woody debris or other initial 

treatments.

Moderate Overstory Removal

None.

Heavy Overstory Removal

Multi-storied stand (4a). Repeated heavy commercial 

thinning to residual stocking levels creating understory 

light levels sufficient for establishment and recruitment of 

shade-intolerant tree species, both natural and planted. 

Stands will ultimately consist of ~5 cohorts with first 2 to 

3 dominated by Douglas-fir and later cohorts dominated 

by more shade-tolerant species. Thinned 100 percent 

of stand from below to RD 20. Underplanted stand 

with an even mixture of Douglas-fir, western hemlock, 

western white pine, and western redcedar at a 10- × 10-ft 

spacing. No woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; lichens, mosses, and bryophytes; snags; woody 

debris; wood production; forest floor.

Study Plan: Tucker, G.F.; Emmingham, W.H.; Overton, 

J.P.; McKee, W.A.; Mayo, J.H.; Cissel, J.H. 2001. The H.J. 

Andrews Experimental Forest Uneven-Aged Management 

Project: study plan. On file with: P. Anderson, U.S. 

Department of Agriculture, Forest Service, Pacific Northwest 

Research Station, Forestry Sciences Laboratory, 3200 SW 

Jefferson Way, Corvallis, OR 97331.

Web Site: http://www.fs.fed.us/pnw/bcfp/research_projects/

UAMP.htm (last accessed December 6, 2006).

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UAMP
44

GENERAL TECHNICAL REPORT PNW-GTR-713

Appendix 12—Young Stand Thinning and Diversity Study (YSTDS)

Initial Installation Years: 1994–1996

Primary Objectives: Provide 

scientific information on the biological 

consequences of thinning. Provide 

agencies with experience in adaptive 

management that enhances both the 

creation of timber-related jobs and 

increased production and utilization of 

wood fiber.

Pretreatment Conditions: 35- to 

45-year-old, even-aged, Douglas-fir 

(Pseudotsuga menziesii [Mirb.] Franco) 

plantations.

Locations: Blue River (44.1000°N, 122.2500°W), McKenzie 

Bridge (44.1786°N, 122.2708°W), and Oakridge (43.8857°N, 

122.3438°W).

Initial Treatments: Three thinning treatments and one 

unthinned control each replicated 1 or 2 times at 3 locations.

No Overstory Removal

Control (1a). No treatment. Provide baseline. Not thinned. 

Not planted. No woody debris or other initial treatments.

Light Overstory Removal

Light thin, no gaps (2a). Timber production and wood 

quality. Thinned 100 percent of stand to 100 to 110 

trees/ac. Not planted. No woody debris or other initial 

treatments.

Light thin, gaps (2b). Maximum horizontal and vertical 

heterogeneity. Patch-level approach to creating and 

enhancing the understory. Thinned 80 percent of stand 

to 100 to 110 trees/ac. Cut 20 percent of stand to create 

0.5-ac gaps one tree height in diameter (~80 ft at initial 

treatment). Gaps planted. No woody debris or other initial 

treatments.

Moderate Overstory Removal

None.

Heavy Overstory Removal

Heavy thin (4a). Accelerate the development of latesuccessional habitat. Stand-level approach to creating 

and enhancing the understory. Thinned 100 percent 

of stand to 50 to 55 trees/ac. Underplanted. No woody 

debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory 

vegetation; small mammals; birds; snags; woody 

debris; fungi; soils; social perceptions; wood production, 

operational factors; forest floor.

Study Plan: No formal study plan found, although several 

study plan-like files exist. On file with: P. Anderson, U.S. 

Department of Agriculture, Forest Service, Pacific Northwest 

Research Station, Forestry Sciences Laboratory, 3200 SW 

Jefferson Way, Corvallis, OR 97331.

Web Site: http://www.fsl.orst.edu/ccem/yst/ystd.html and 

http://www.fsl.orst.edu/ccem/youngstd/home (last accessed 

December 6, 2006).

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YSTDS
Pacific Northwest Research Station

Web site http://www.fs.fed.us/pnw/

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