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Research on Wildlife in Old-Growth Forests:

Setting the Stage

Jack Ward Thomas

Author

JACK WARD THOMAS is chief research wildlife biologist,

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

Northwest Research Station, 1401 Gekeler Lane, La Grande,

Oregon 97850.

Scientifically based forest management proceeds, at best, on

the basis of available information. Such information is generally archived in scientific journals, however, and is often

neither readily available nor useful to forest managers.

Thousands of such pieces of information germane to forest

management reside in untold numbers of largely unread

journals and transactions of symposia, in researchers’ files,

and in the minds of knowledgeable individuals. This is

especially true for information on the relationships between

wildlife and their habitats. In the forms I have listed, that

knowledge is not useful in guiding managers of National

Forests in meeting the legal mandate to “maintain viable

populations of all native and desirable non-native plant and

animal species well-distributed throughout” the managed

forest.

Some 15 years ago, ad hoc groups of natural resource management professionals began to gather and synthesize existing information on wildlife habitat relationships for use in

forest management. Those early work groups published a

series of compendia-first for the Blue Mountains in Oregon

and Washington (Thomas 1979) and the Southwest (Patton

1978), and then for the Sierra Nevada of California (Vemer

and Boss 1980), New England (DeGraaf and Rudis 1986),

Colorado (Hoover and Wills 1984), and Oregon and Washington west of the Cascade crest (Brown 1985). The ideas

and approaches presented in these documents evolved into

the Forest Service’s Fish and Wildlife Habitat Relationships

Program, whose mission is to encourage the development

and updating of synthesis documents describing wildlife

habitat relationships in forested ecosystems across the United

States. Similar efforts are underway in Canada.

Examination of these documents quickly reveals gray areas

where information is contradictory or absent or where authors

relied on their judgment to formulate working hypotheses to

fill gaps in published data. Research can then be directed to

the information needs that are most germane to the resolution

of conflicts inherent in multiple-use forest management. The

allocation of resources for large-scale research programs,

however, will occur only where such conflicts result in significant social, economic, and political impacts.

Nearly all the documents listed previously put forth the hypothesis that the forest state that exists at, or approaching,

the culmination of forest succession-old growth-is a

significantly different habitat for wildlife than earlier, more

structurally simple states. Some wildlife species were hypothesized to find their preferred or only habitats in old

growth, and species diversity was expected to be higher

there. These hypotheses were formed from observation and
experience, some research results, and the assumption that,

because most forest stands were in the old-growth state in

historic times, some species of wildlife have evolved largely

in old growth.

These hypotheses were used in the Forest Service’s ongoing

land-use planning. Immediate and intense controversy over

the amount of old-growth forests to be preserved ensued and

is currently increasing. When Forest Plans called for retaining

old growth to meet the needs of wildlife, sometimes the

amount of timber that could be offered for safe declined.

Conversely, those interested in preserving old growth, for

whatever reason, pushed vigorously to achieve their goal;

concern for wildlife was foremost among the arguments

presented.

The controversy became most pronounced in western Oregon

and Washington, where significant amounts of old growth

containing very old and very large trees, particularly Douglasfir, still exist. Such stands have high economic value per tree

and per acre. Coupled with the potential economic values of

those stands were the social and political consequences of

jobs retained or lost and issues of community stability associated with the annual timber harvest anticipated under

various management alternatives.

The inevitability of these conflicts was obvious to some,

even a decade ago. Examination of how the law evolved

through the Multiple Use-Sustained Yield Act of 1960, the

Endangered Species Act of 1973, the Forest and Rangeland

Renewable Resources Planning Act of 1974, and the National

Forest Management Act of 1976 reveals an increasing emphasis on the multiple-use philosophy in National Forest

management (Thomas 1979; U.S. Department of Agriculture,

Forest Service 1983). These changes strongly emphasized the

need to recognize the importance of water, wildlife, recreation, and forage, in addition to wood production. This emphasis inevitably led to increasing debate over how, and in

what quality and quantity, old growth would be retained as

part of the managed forest.

Maintaining biological diversity, as an overriding goal for

Federal land management, has played an important role in

the evolution of Iaw and thought about how land is to be

managed. This evolving concern encompasses retaining the

diversity of plant and animal life, forest structure, human

experience related to the forest in its many forms, and an

expansion of management concerns from the immediate and

the site-specific to long-term considerations of changing landscapes over time. These concerns seem likely to become

embodied in law and regulation.

These changes in laws and regulations strongly influence

management philosophy for the National Forest. New words

and concerns reach the ear of natural resource management

professionals and the scientific community with increasing

frequency--biodiversity, landscape ecology, conservation

biology, environmental ethics, and new perspectives in

forestry. Public forest managers are becoming convinced that

maintaining biological diversity should be the overriding

land-use management objective. Whether or not this momentum will force adjustments in how natural resource management is conducted after it becomes clear that meeting such a

mandate is very difficult, lies in the future-perhaps the near

future. The increasing political uproar in the Pacific Northwest over old-growth management will not be easily resolved.

And the resolution of this conflict, whatever it is, will likely

not be popular-not with the timber industry and not with

environmentalists.

Those who foresaw threats to preserving biodiversity in

managed landscapes conducted small, but now significant,

research efforts on the interactions between wildlife and

old-growth habitat. Among these efforts were studies on the

habitat associations of northern spotted owls in Oregon

conducted by an Oregon State University graduate student

with modest Forest Service funding; these studies marked the

beginning of the spotted owl issue. The total expenditure for

those early studies was certainly much less than the cost of

publishing this volume.

The northern spotted owl was found to be associated primarily with the forest structure that is most common in old

growth in the Douglas-fir region. This observed association

with a habitat that was being systematically diminished and

fragmented would eventually lead to listing of the owl as

threatened by the U.S. Fish and Wildlife Service. As a result,

much subsequent research and management attention has

focused on the northern spotted owl. The consequences of

such initial small-scale studies reverberate today in many

scientific and political debates. This research, together with

the evolution in law concerning forest management over the

past two decades, set the stage for the research reported in

this book.

By 1978, a well-funded, broad-scale research effort was

clearly needed to evaluate the hypothesis that old growth is

a significantly different wildlife habitat than younger forests.

A Forest Service Research and Development Program was

instituted in 1982 at the Pacific Northwest Research Station

in Olympia, Washington, to address these issues. Technical

experts were brought together to formulate the research

2
approach. Until then, public attention and the emphasis of

research was focused on the northern spotted owl. The teams

that had gathered information on wildlife habitat relationships in Douglas-fir forests (Brown 1985), however, had

identified other wildlife species that were likely to have

primary habitats in old-growth forests.

Advice came from consultants to put the emphasis on studies

of wildlife species identified as likely to be closely associated

with old growth. Such studies would be relatively straightforward (as compared to studies of plant and animal communities) and easier for promoters of the research to understand and support. Furthermore, this approach was best suited

to satisfying forest managers’ demands for information to use

in response to requirements arising from the Endangered

Species Act of 1973. This research approach would undoubtedly meet with strong support from those actively

involved in the developing old-growth management issue.

The research alternative was to emphasize community

studies. Compared to studies on selected species thought to

be closely associated with old growth, community studies

would be more technically complex, difficult to understand

by the concerned public, expensive to conduct, and hard to

explain. And, in the end, they would require innovative

syntheses of the results from separate studies conducted

across a spectrum of environmental gradients. Though not as

politically expedient, the community approach seemed best

from a scientific standpoint. The community approach would

not, however, satisfy the demands for immediate answers to

questions about the habitat relationships of key species, such

as management indicator species. These species would loom

larger still in the press as resource conflicts intensified and

management plans were appealed. Furthermore, the temptation to simplify this extremely complex biopolitical issue

as one of spotted owls (or some other species) versus jobs,

profits, or some other criteria, would be great.

To their credit, Leonard Ruggiero, the research program

manager, and Andrew Carey, the research coordinator, put

primary emphasis on questions of old-growth community

ecology. Attention was focused on fundamental questions

concerning the form and function of the old-growth ecosystem to produce answers that would satisfy demands of the

moment, but would also be germane to the larger questions

that would arise as the debate continued.

This volume reports the results of those community studies.

These studies were designed to provide answers to a number

of questions. Foremost among these was, is Douglas-fir old

growth significantly different as wildlife habitat from other

stages of forest development? Corollary questions are, If

significant differences exist, what are they? How pronounced

are the differences? How might these differences be preserved

or modified most effectively and efficiently through forest

management? To provide these answers is no small shore.

Questions about the uniqueness of old growth as wildlife

habitat will change over time, beyond current emphases on

individual species to the larger and more significant issues

of community stability, aesthetic values, and maintaining

biodiversity.

The legal and conceptual tools provided by the Endangered

Species Act of 1973 and the National Forest Management

Act of 1976, coupled with an emphasis on managing indicator species in Forest Service planning, have led to a

situation where the welfare of a single species drives the

debate on the premier natural resource allocation issue of

this quarter-century in the United States. This, perhaps inevitable, course has led to an unfortunate trivialization of a

much larger and more significant issue-preserving and

perpetuating significant amounts of unique ecosystems in

such a fashion that they function as they evolved. In this

approach lies the only real chance for maintaining

biodiversity.

The political strategies of various factions in the old-growth

allocation controversy have produced a situation where

economics, social concerns, and biology have become so

inextricably tangled that knowing where science and

economic analyses end and politics begins is increasingly

difficult. The initial emphasis on understanding the habitat

relationships of spotted owls, and of ensuring their survival,

was a logical, probably inevitable, outcome given the state of

knowledge on the ecology of old growth and the desire and

necessity to meet requirements of law and regulation within

reasonable time frames for the drafting of National Forest

Plans.

I am not saying that research and management activities

directed at individual species will cease-nor should they.

In fact, the old-growth issue has become a crucial regional

and national issue with the recent listing of the spotted owl
by the Fish and Wildlife Service. The chaos, conflict, and

intense political activity that have emerged, however, will

eventually lead to societal consideration of much larger and

more complex questions about the form and function of

entire ecosystems in a rapidly changing world. The political

implications of this debate will extend far beyond the borders

of the Pacific Northwest or of the United States. How our

country resolves this conflict will strongly influence lessaffluent nations as they struggle with resource allocations.

This debate will not take place in isolation. Rather, it will

occur in the context of emerging concerns about global

climate change and the loss and fragmentation of forest

ecosystems throughout the world.

The information presented in this volume will be quickly

applied in the management arena and will come to beartechnically and politically-on forest management. Such

research represents incremental steps toward truth, appreciation, and understanding. All concerned with the oldgrowth management issue should welcome closer and closer

approximations of truth.

4
Wildlife Habitat Relationships in Unmanaged

Douglas-Fir Forests: A Program of Research

Leonard F. Ruggiero

Author

LEONARD F. RUGGIERO was a supervisory research

wildlife biologist, U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station, Olympia,

Washington 98502. He is now at Rocky Mountain Forest and

Range Experiment Station, Lammie, Wyoming 82070.

The research reported in this book is the result of a single

Forest Service research initiative called the Old-Growth

Forest Wildlife Habitat Research and Development Program

(Ruggiero and Carey 1984). The Program focused on the

Douglas-fir forests of western Oregon, western Washington,

and northern California. The Old-Growth Program initially

included Region 5 and Region 6 of the National Forest

System and the Pacific Southwest and Pacific Northwest

Research Stations; the Bureau of Land Management was an

early cooperator and supporter. The Program-headquartered

in Olympia, Washington--proceeded under the aegis of the

Pacific Northwest Research Station.

Many activities led to the Old-Growth Program. Biologists

like Eric Forsman, Jeny Franklin, Thomas Hanley, Glenn

Juday, William Mannan, Chris Maser, Charles Meslow,

John Shoen, James Trappe, and others had been studying

the ecology of old-growth Douglas-fir forests at least since

the early 1970s. Early old-growth studies conducted in

California by Martin Raphael and Bruce Marcot were the

first to have a major focus on wildlife communities, and

these efforts provided valuable information for the design

of future studies. Insights offered by all of these people led

to growing concerns that old growth was a dwindling and

poorly understood resource that could be crucial to long-term

forest productivity and to the survival of numerous plant and

animal species.

A great deal of public interest was generated by these and

related issues during the mid-1970s through the early 1980s.

And all this led to major changes in the way land managers

and the public thought about old-growth forests. For example,

the notion that late-successional forests were “biological

deserts” was being effectively challenged; the spotted owl

had emerged as an example of close interrelationships

between wildlife and late-successional forests; and Jack

Thomas’ book (1979) about wildlife habitat in Oregon’s

Blue Mountains had challenged the conventional wisdom

that good timber management is good wildlife management.

By 1981, concerns about managing old-growth forests in

the Pacific Northwest were running high. A series of public

meetings confirmed a great deal of interest in old-growth

issues. In response, the Forest Service chartered the OldGrowth Program-the first step towards initiating the

research reported in this book.
The Old-Growth Program objectives were to (1) define

old-growth Douglas-fir forests, (2) identify wildlife species

closely associated with these forests, and (3) determine the

biological requirements and ecological relationships of

closely associated species. The intent was to do research

that would provide forest managers and decisionmakers

with some of the tools they need to maintain viable wildlife

populations on lands of the National Forest system. This

problem was, and still is, important for land managers

because the National Forest Management Act of 1976 and

related regulations contained clear mandates to maintain or

enhance biological diversity and to maintain viable populations of all native vertebrates. Learning more about wildlife

habitat relationships in old-growth forests was thus extremely

important, especially in the Pacific Northwest where the

remaining Douglas-fir old growth had very high economic

and social value.

My first objective as program manager was to complete a

plan called the Program Direction Document. This plan

benefited from the contributions of an early ad hoc advisory

group comprised of John Faaborg, Jerry Franklin, Martin

Raphael, Hal Salwasser Fred Samson, Mark Shaffer, and

Jared Vemer. The plan indicated forest fragmentation as a

key consideration in Program research. The plan also recognized the necessity for studying vertebrate communities

(patterns of vertebrate abundance) in all stages of forest

development. A detailed account of the experimental design

is presented by Carey and Spies elsewhere in this volume.

For my purposes here, simply note that the research plan we

went on to develop called for a very ambitious, highly

integrated, cooperative research effort.

The Program’s charter limited our planning horizon to 5 years

and, for that period, the funding needed to implement the

plan was estimated to be $10 million. We actually ended up

with around $2 million as the basis for all the studies being

reported here. This funding shortfall resulted in some significant problems. For example, we were not able to conduct

the forest fragmentation studies we had planned, and both the

geographic scope and duration of our community studies

were greatly reduced.

The Old-Growth Program staff managed and coordinated the

research effort; others did most of the actual data collection

and analysis. We soon learned about the difficulties of coordinating and integrating the efforts of a team of scientists

from three major universities, three Forest Service laboratories, and two units of the Fish and Wildlife Service.

Several important practical constraints influenced the scope

and conduct of Program studies. For example, in spite of

requests to be included from Alaska, eastern Oregon, and

eastern Washington, we were forced to limit the geographic

scope of our studies. In addition, the relatively small sizes

and young ages of existing managed stands led us to conduct

most of our sampling in naturally regenerated, unmanaged

stands. Thus, comparisons of young, mature, and old-growth

forests would be complicated by the residual components of

old growth (such as large trees, snags, and logs) that carry

over to the new, younger stands after a catastrophic disturbance like fire. Many authors will discuss in detail how this

situation affected study results and also how it generated

important insights about the influences of this natural structural complexity on patterns of vertebrate abundance.

In addition to the practical constraints on geographic scope

and kinds of stands sampled, we were also constrained by

available funding to study either vertebrate communities or a

limited number of high-visibility species that were thought at

that time to be closely associated with old growth. We could

not do both. Because relatively little wildlife research had

actually been done in the geographic area of concern, we

decided to emphasize the community approach.

The decision to emphasize communities involved a major

tradeoff because several large, highly mobile species would

not be well represented in our community sampling. In addition, we were trading the opportunity to learn a great deal

about the ecology of a few species for the opportunity to

learn about the patterns of abundance of many species. Ouroriginal intent did not include these compromises; we had

planned to begin the more intensive species-specific studies

after the first 2 years of the community studies. These intensive studies would have further defined the mechanisms and

the nature of observed habitat associations while producing

the information needed for more precise management recommendations. The need for intensive studies of certain species

or species groups is now more acute than ever.

I would like to acknowledge that our Program efforts benefited from the scientific advice of a Technical Committee

and the guidance of an Executive Committee. The Technical

Committee was comprised of John Faaborg, Jerry Franklin,

Chris Maser, Richard Pederson, James Rochelle, Fred

Samson, Mark Shaffer, Jack Thomas, Robert Vincent, and

Bruce Wilcox. The Executive Committee included representatives from State and Federal land management agencies,

environmental groups, and the timber industry.

6
I would also like to acknowledge the Bureau of Land Man- beyond normal limits to get the job done. If you have ever

agement for their unfailing commitment to our research spent 10 hours a day 7 days a week fighting through dense

efforts. The Oregon State BLM office has provided yearly vegetation on steep, west-side slopes, and then worked into

funding since 1981. We are grateful to Jerry Asher, Stan the night processing data, cleaning traps, and preserving

Butzer, William Leave, Joseph Lint, William Luscher, specimens, you have some idea of the effort they made. We

Robert Metzget, and William Neitro for their support. owe each of these biologists a tremendous debt of gratitude

for their perseverance and dedication to the resource. 

The real credit, though, must go to the 200 or so field biologists who put forth the herculean efforts required to collect

the data reported here. Most of these people worked way

Sampling Design of the Old-Growth Forest

Wildlife Habitat Program

Andrew B. Carey and Thomas A. Spies

Authors

ANDREW B. CAREY is a research wildlife biologist,

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

Northwest Research Station, Olympia, Washington 98502,

and THOMAS A. SPIES is a research forester, U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station, Corvallis, Oregon 97331.

Introduction

The Old-Growth Forest Wildlife Habitat Program (the

Program) was chartered in 1981, with four objectives:

. To identify animal and plant species that are dependent

upon or find optimum habitat in old-growth forest stands;

. To define, classify, and inventory old-growth forest

ecosystems;

. To determine the biological requirements and ecological

relationships of species that are found only in old growth

or find optimum habitat there; and,

. To evaluate old-growth management alternatives and

determine economic aspects of old-growth forest

ecosystems.

The first step taken to achieve these goals was to implement

studies of wildlife and plant communities in different-aged

Douglas-fir forests. A research plan was developed in 1982.

The purpose of this paper is to describe in detail the research

that was planned and discuss some of the major problems

encountered in its implementation. Although several aspects,

of the research were not conducted because of budget constraints, we include a detailed description of the original plan

for use by others in future studies. Details of the sampling

designs and analytical approaches used for the various communities studied in each province are described in the individual papers that follow.

Providing the basis for the Program approach were the sampling and statistical considerations discussed in Capen (1981)

Cochran and others (1954), Eberhardt (1976), Gauch (1982),

Green (1979), Pielou (1977), Ralph and Scott (1981), Scott

(1982), and Snyder (1978); ecological descriptions provided

by Franklin and Dyrness (1973), Franklin and others (1981)

and Lang (1980); the expertise of the Program staff and

technical committee; and review comments on draft

proposals.

The Program charter called for accelerated research and

development that would be applicable to a large geographic

area. All research endeavors are constrained by time, money,

and personnel, however, and we recognized that the plan

would have to change as new information developed, constraints changed, or research objectives altered.

9
Scope of the Research

The biogeographic scope of the Program was the Western

Hemlock Zone, lower elevations of the Pacific Silver Fir

Zone, the Mixed-Conifer Zone, and the Mixed-Evergreen

Zone (Franklin and Dymess 1973) in Washington, Oregon,

and northern California where Douglas-fir is the dominant

tree species in seral stages of forest development through

subclimax. These regions span 8 degrees of latitude and

encompass at least eight physiographic provinces (see

frontispiece). Because the structure and composition of

Douglas-fir plant communities vary among these physiographic provinces, the sampling plan included geographic

stratification. These communities may also vary markedly

along moisture and temperature gradients within provinces.

Consequently, these gradients were also included in the

sampling plan.

The sampling plan for each geographic replicate was to

include both managed and unmanaged stands, but we found

that managed stands were few, and often either too small or

too young to be included. Although the program focused on

the uniqueness of old-growth Douglas-fir communities, we

also had to study biotic communities found in earlier stages

of forest development for comparison. If our research was to

provide new information relevant to forest management, we

needed to assess the potential effects of management on the

structure and composition of seral communities. Including

the entire sere of forest development in sampling plans was

impractical, but we could include at least those stages that

would be expected to constitute the oldest managed stagesstands that are regarded by foresters as the last stage before

harvest. We planned to describe all earlier stages through a

review of the literature to ensure that community patterns in

old-growth Douglas-fir were viewed in the full context of

forest development.

We also planned to conduct an old-growth inventory independently of (hut concurrent with) the plant community

studies. Funding constraints, however, prevented us from

conducting the inventory.

Pilot Studies

We planned experimental sampling with various methodologies both to ensure that target populations would be

adequately sampled with our methods, and to assess the

natural variability within our study areas in order to determine the sampling intensity required to ensure statistically

reliable sample sizes. These pilot studies would also enable

us to evaluate the experimental design to ensure that the

stratification and the gradients (and treatments) identified

in the sampling plan were sufficient to meet the study’s

objectives. Pilot studies were to be performed before a final

sampling plan was developed and implemented.

Vegetation pilot studies were not needed. A number of

vegetation studies, including preliminary classifications of

Douglas-fir communities, had been conducted throughout

the region (see Franklin and Dymess 1973). Previous vertebrate community studies sponsored by the Pacific Southwest Region of the Forest Service and conducted by M.G.

Raphael and R.H. Barrett at the University of California at

Berkeley and B.G. Marcot at Oregon State University provided the Program with a substantial amount of information

on sampling birds and forest-floor vertebrates (see Raphael

and Barrett 1981, Raphael and Rosenberg 1983, Raphael and

Marcot 1986). Little information, however, was available

on sampling bats, arboreal mammals, fossorial mammals,

raptorial birds, or aquatic amphibians. Although we fully

recognized the ecological and economic importance of

invertebrate communities, we had insufficient resources to

describe these communities adequately.

Sampling Considerations

General questions can be answered with descriptive statistics.

When the objective is to test specific hypotheses, however,

statistical considerations become more important, and greater

constraints are put on the sampling plan.

We planned studies at the community scale to answer the

following general questions: Do old-growth stands represent

a unique forest ecosystem? Do old-growth stands contain

distinct fauna1 associations? Do certain species find optimal

environments in old-growth stands? Are any species found

only in old-growth stands? How do we classify old growth

for inventory purposes? Answers to more specific questions

were also sought: What changes take place in a developing

Douglas-fir forest community after trees become dominant?

How do management activities affect these changes? Do

these changes differ significantly among physiographic

provinces? Do these changes differ significantly within

provinces because of topographic position, site quality, or

position on a temperature or moisture gradient? Do the

effects of management activities change with province, or

within province with site?

Previous work on the plant communities in this region

(Franklin and Dymess 1973) suggested that we stratify our

sampling by physiographic provinces. Five provinces were

originally planned to be sampled: the Northern Cascade

Range, Southern Washington Cascade Range, Oregon

Cascade Range, Oregon Coast Range, and Klamath

Mountains in southern Oregon and northern California

(see frontispiece).

The best possible approach would have been to complete

an inventory of all late-seral Douglas-fir stands in each

physiographic province before choosing stands for study.

We could then have randomly selected stands in each

10
stratum, accurately estimated the variability within and

among stands, and used rigorous statistical tests of hypotheses about the similarity of gradients, community

structure, and community composition in different forest

types. In addition, sampling using quantitative methods

would have resulted in reliable and generalizable models

of forest development and environmental gradients. Unfortunately, this approach would have poorly met the needs

of a research program that was constrained in both time and

resources. Although a departure from this approach entailed

risks of incomplete information and consequent failure of

classifications or predictions, the need to produce timely

and reliable information eventually took precedence.

We chose to describe and classify late-seral stages of

Douglas-fir communities in these five provinces by

preferentially (see Gauch 1982) sampling sites that

represented the full range of variation occurring along age,

moisture, and temperature gradients. Although the sites

would not be random samples, the chance of not encompassing the ranges of natural variation would be less than

for random sampling with the same number of samples.

Good descriptions of community patterns would be obtained

if no unknown biases influenced the selection of study sites.

Because practically all statistical tests are based on random

samples, however, tests for differences among strata or

among sites (stands) could only be used heuristically. Likewise, classifications derived from preferentially sampled

stands would represent potential communities-they could

not be presumed to be applicable to all stands.

Plant Community Studies

Sampling

We planned to select a series of homogeneous sites that

represented the full range of variation occurring along seral

and moisture-temperature gradients. Replicate sites would be

chosen. We planned to calculate the number of replicates

(and sample sizes within replicates) required using measures

of dispersion estimated in previous studies (see Franklin and

Dymess 1973). We also planned to include riparian areas, as

well as managed stands.

We planned to study both the structure and composition of

the plant communities. Different sizes, shapes, and numbers

of sampling units were to be used in sampling plant taxa.

For example, Gauch (1982) recommended quadrats of 0.1 to

0.4 m2 for epiphytes, 1 to 4 m2 for mosses, and 200 to

800 m2 for trees. In addition to commonly measured compositional elements, special attention would be paid to cryptogams, particularly lichens and fungi. Sampling hypogeous

fungi would be attempted. The use of modified life-form

categories would be considered for describing some aspects

of stand structure and as part of the classification system.

Structural elements of wildlife habitat that would be

quantified included crown structure, snag and log abundance (by both size- and decay-classes), litter depth and

humus development, vertical layering of the vegetation, and

diameter-class distributions. A substantial effort would be

made to ensure that data was collected in such a way that

the results of the study would be compatible with information systems used by the National Forest system.

Analysis

Gradient analyses would be used for both stand-by-structure

data and stand-by-species data. Direct gradient analysis

would help to identify nonlinear responses to gradients and

aid in interpreting more sophisticated analyses. In addition,

direct gradient analysis would provide heuristic illustrations

of community patterns and help to identify “potential” communities associated with major segments of gradients.

Ordination (for example, detrended correspondence analysis

and nonmetric multidimensional scaling) of site-by-species

and site-by-structure matrices of appropriately transformed

and standarized data was planned to determine the major

components of variation in the data resulting from complex

gradients. Classification algorithms were then to be used to

identify more objectively defined “potential” communities

than is possible with direct gradient analyses. After the data

were analyzed within strata, we planned similar analyses

among strata to determine if regional gradients exist.

Products-The plant community study was to produce:

. A definition of old growth;

. A classification of late-seral Douglas-fir communities;

. A classification algorithm that could be tested on a new

set of randomly selected late-seral Douglas-fir stands;

. Heuristic descriptions of forest development;

. Heuristic descriptions of the effects of major

environmental gradients;

l Quantification of community patterns along complex

gradients;

. Identification of “potential” communities associated with

parts of complex gradients;

. Qualification (possibly quantification) of plant species’

responses to gradients, including

-Taxa closely associated with old growth,

-Correlations (negative and positive) between certain

species and certain environmental variables, and

-Correlations (negative and positive) between species;

and

Research hypotheses on:

. The effects of management on community structure and

composition, and

. The effects of management on certain plant groups.

11
Vertebrate Community Studies

Sampling

Sampling vertebrate populations is much more complex than

sampling terrestrial plant populations, in part because of the

mobility of vertebrates and the tendency of their populations

to vary in size both among seasons and among years. One

visit per sampling unit is often adequate for many purposes

in vegetation sampling, such as estimating the density, size,

and species composition of trees. In contrast, 8 to 10 visits

per site in each of four seasons for at least 3 years would be

necessary to adequately estimate the species composition and

population density of a bird guild characteristic of that particular site. In addition, a variety of sampling techniques are

required to sample different vertebrate populations, and

quantitative techniques are lacking for many key species,

such as marbled murrelets, Vaux’s swifts, and red tree voles.

We decided the best approach to selecting stands for vertebrate community studies would be to subsample the stands

preferentially chosen for plant studies. This was to be accomplished by randomly choosing three replicates of at least

15 stands, with each replicate representing the full range of

variation in late-seral stages. The total number of stands (45)

was consistent with the work done by Raphael and Barrett

(1981), which suggested that 45 stands was a suitable number for a team consisting of a field crew of four and total

technical support of less than 10 people. We recognized that

statistical tests could be applied with this sampling plan, but

that samples would be drawn from preferentially chosen

stands, not from all existing stands. The skill with which the

preferential sampling was conducted was an essential element

of many aspects of the Program. Our approach assumed that

sample sizes for plant studies would greatly exceed 45 per

stratum. Gauch (1982) suggested that a minimum of 50 to

60 stands per plant community type are necessary in areas

with high environmental variation, whereas 50 to 100 homogeneous stands are necessary in substantially disturbed

landscapes.

The ordination of stands along environmental gradients

resulting from the plant study would provide a template for

measuring the habitats of the vertebrates. Vertebrate ecologists were to examine gradients within the communities

sampled to quantify vertebrate niches. These studies would

provide descriptions of the structure and composition of the

vertebrate communities and of the habitat relationships of

vertebrate species: Environmental variables that are predictors (discriminating variables) of potential vertebrate

communities associated with late-seral Douglas-fir stands

could then be determined.

Study Establishment

The boundaries of stands chosen for study were to be drawn

on topographic maps. A 50-m “no sampling” zone would be

located within the periphery of the stand. Slope, aspect, and

the location of riparian zones was to be noted. An initial

transect line oriented to the elevational gradient was to be

randomly located within the stand. Subsequent transect lines

would then be located at 200-m intervals parallel to the

initial line. The starting point of each line was to be located

at a random distance of less than 50 m from the no sampling

zone. These transects would serve as reference lines for

locating sampling points, plots, lines, and grids. Lines along

the elevational gradient would provide the basis for describing the stand, whereas lines perpendicular to riparian zones

would be used to study riparian effects. Sample shapes, sizes,

and numbers were to vary with the sampling technique used,

the homogeneity of the area (as defined by the mobility of

the species sampled), and the life history traits of the target

species. All samples were to be replicated over time (some

by weeks, seasons, and years; some just by years).

Analysis

Procedures similar to those outlined in the plant community

data analysis section were to be followed. In addition, because we recognized that the reliability of density estimates

will differ greatly among species, abundance values were to

be standardized over all stands. The year-to-year dynamics of

each species’ status (its abundance and role in the various

stands) were to be examined and interpreted before further

analyses were completed. If analyses warranted, null model

simulations were to be used to examine associations among

species and to address questions of species’ dependencies on

old growth.

Even though only stands > 40 ha were to be sampled, they

would be “large” to some species, such as amphibians and

small mammals, but “small” to other species, such as

carnivores and raptors. Consequently, the effects of stand

size would also be considered. For example, cluster analysis

was to be used to classify groups of stands on the basis of

species assemblages (vertebrate community composition).

Multivariate analyses would then be used to separate the

stands in a multidimensional “environmental” space. The

magnitude of the contribution of each species to the community classification was to be determined by examining

the ratio of the among-community variance to the withincommunity variance of the species’ log-transformed or

standardized abundance (similar to an F-test). Multivariate

analysis of variance and multivariate analysis of covariance

would then have to be used to determine if stand size

provided a significant degree of separation and, if it did,

whether other environmental variables also contributed

significantly to the separation of clusters.

12
Within-stand analyses were to be used to compare patterns

of species abundance within stands to patterns among stands.

Each stand was expected to contain some portion of the gradients operating across all stands. Comparison of species’

abundances across each gradient with the portion of the

gradient occurring within each stand was to be used to

explain community patterns and provide descriptions of each

species’ adaptability to gradients of limited scope. If certain

species were absent from small stands but present in large

stands, this approach was to be used to formulate hypotheses

about mechanisms underlying the effect of stand size on

community composition. Furthermore, potential competitive

interactions could be explored by contrasting the portions of

gradients occupied by a species in the presence of another

species to the portions of gradients occupied in the absence

of that species.

We planned to contrast classifications of stands based on

vertebrate community composition to classifications based

on plant community structure, composition, or both. If

community classification based on plant data is to be used

for management purposes, it is crucial to understand how

these plant communities are related to the vertebrate

communities.

Products-The vertebrate community study was to produce:

.

.

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.

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.

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.

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.

.

A list of species closely associated with old growth;

A classification of vertebrate communities found in

late-seral Douglas-fir communities;

A classification algorithm for “potential” communities

that could be tested on a set of randomly selected

late-seral Douglas-fir stands;

Heuristic descriptions of species’ responses to forest

development;

Heuristic descriptions of species’ responses to major

environmental gradients;

Quantification of vertebrate community patterns along

complex gradients;

Descriptions of species’ responses to extensive complex

gradients (species’ habitats);

Descriptions of species’ responses to intracommunity

factors (species’ niches);

Predictions of the effects of large-scale management

activities on vertebrate community structure and

composition;

Descriptions of species’ responses to management

activities;

A comparison of plant community classifications to

vertebrate community classifications;

A description of the role of riparian zones in late-seral

vertebrate communities;

A measure of the effect of stand size on community

composition;

. A list of key species, environmental variables, and

gradients for late-seral Douglas-fir stands; and

Research hypotheses on:

The effects of stand size,

The effects of competition, and

The effects of predator-prey relationships.

Insular Ecology Study

The fragmentation of old-growth Douglas-fir forests may

result in substantial changes in the wildlife and plant communities occurring in those forests. Both community and

species-specific studies are necessary to assess the effects of

forest fragmentation and to provide guidelines for mitigating

them. The impact of fragmentation largely depends on the

sizes and patterns of abundance of the resulting old-growth

stands. The smaller the stand and the more disparate the

environment surrounding the stand (the stand context), the

greater the pressure would be from early-seral species on

old-growth species. If an old-growth stand was only marginally capable of supporting populations of species that

require old growth for population persistence, and if it was

not near (relative to the dispersal abilities of those species)

other old-growth stands, these populations would eventually

become extinct. Additional causes of the species/area effect

are unknown, but presumably could operate in these situations. Finally, at some lower size limit, the stand would

begin to lose its old-growth characteristics because of environmental influences alone, such as successive loss of

trees at the periphery from blowdown and drier microclimates within the stand from edge effects.

The species/area relationship in sampling makes the problem

of studying the effect of stand size and stand context difficult.

For example, if IO-ha plots were randomly sampled in an

extensive old-growth forest, we would not expect to find

many plots containing all the key species representing that

forest’s community. Indeed, the average composition of

species on the 10-ha plots would probably differ from that

of a random sample of 20-ha plots, even if the total areas

sampled were equal. Thus equal-sized plots were to be

compared among stands of different sizes.

To study fragmentation, we planned to use a sample plot

size between 1 and 10 ha. Such a small plot provides a high

probability that any particular species would not be detected,

so many plots were to be randomly sampled to estimate the

probability of a particular species being present. Plots were

to be located within randomly selected stands that were 0 to

10,20 to 40, and 80 to 160 ha. The effects of stand size at

the large end of the scale would also be evaluated in the

vertebrate community studies.

1 3
The stands thus chosen were to be cross-classified according 

to stand context, “potential” old-gmwth community classification (from the vegetation study), and the presence or 

absence of species associated with old growth. TIE resulting 

data would be placed into a contingency table conditioned on 

stand size. Discrete multivariate analysis (log-linear analysis) 

was to be used to test for independence between and among 

the categories. A table of expected cell frequencies was to be 

used to estimate the probability that a stand of a particular 

size, context, and vegetation class would have none, some, or 

most old-growth species. The magnitude and direction of 

interactions were to be reported in the tables of the ratios of 

the log-linear panmeter estimates to their standard errors. An 

important feature of this approach is that the effects of fragmentation (size, context, and class) are as likely to be multiplicative as linear, and whereas this presents problems in 

analysis of variance designs, it does not in log-linear model 

analyses. 

Species-Specific Studies 

The insular ecology study was to examine the general effects 

of old-growth forest Fragmentation on wildlife and plant communities. Certain species deemed to be sensitive to the loss 

or alteration of old-growth habitats were also ‘O be studied in 

detail to identify management prescriptions that might be 

applied to ensure viable populations. Several species had 

been identified as sensitive to the loss of extensive areas of 

old growth, the foremost being the spotted owl. The Program 

initiated two studies on the spotted owl and cooperated wilh 

the State of Washington on a third; the results of these. studies 

will be published elsewhere. Similar projects on other species 

were to be initiated as needs became apparent. 

We planned species-specific studies to identify key elements 

of the species’ habitat, quantify its responses to both interand in&+community dynamics, including competitive and 

predator-prey relationships, and examine aspects of its population biology, with emphases on population dynamics, dispersal behavior, and minimum area requirements. These 

studies were to be designed to result in specific management 

guidelines that would ensure species viability. 

Other Research 

The Program charter also called for determining economic 

aspects of old-growth forest ecosystems, evaluating management alternatives, evaluating silvicultwal options (including 

cost/benefit analyses), and determining the role of old growth 

in biological diversity. Because of funding constraints, however, research planning focused primarily on wildlife and 

Because of the interweaving of our research approach, the 

results of these studies were tci be integrated. The results 

would be synthesized to produce management recommendations and data bases that would be available to the National 

Forest system, cooperating groups such as the Bureau of 

Land Management, and other potential users of the information. The goal of synthesizing Program results was to be 

met by several methods, including convening a symposium 

for the presentation of Program results. 

Implementation 

Study Site Selection and Sampling Design for 

Community Studies 

The design chosen for studies of terrestrial ecosystems was 

labeled a “T-matrix.” The result was a five-cell matrix (three 

cells in old growth, one in mature, and one in young) with 

nine stands per cell per province (fig. 1). 

The complex moisture-temperature gradient prevalent in the 

Pacific Northwest was studied only in old growth--equal 

numbers of stands were chosen for provisional categories of 

“wet old growth, ” “mesic old growth,” and “dry old growth.” 

The age gradient was studied only in mesic stands, with 

equal numbers of stands chosen in the provisional categories 

of “mesic young” and “mesic mature.” 

+-Moisture gradient --+ 

14 
The general concept of using this T-matrix design to

structure sampling and data analyses was fundarnentally

sound; however, implementing it in a strict balanced

ANOVA-type design was unrealistic. Although the study

was stratified into physiographic provinces, the provinces

(especially the Oregon Cascade Range) were so large that

within-province variation made it difficult to develop a

single province-wide classification. For example, a dry

old-growth site in the northern Oregon Cascades was

typically quite different from a dry old-growth site in the

southern portion of the province. Objectively classifying

the moisture-status of a 40-ha stand relative to other stands

in the province based on an hour or two of field inspection

was impossible. A major variable that could not be controlled well in stand selection was elevation. Although the

age- and moisture-classes typically had similar mean elevations, considerable elevational variation occurred within

each class. Because elevation represents a complex

temperature-moisture gradient and could compensate for

other factors (such as slope, aspect, and soil depth) that

determine moisture condition, the simple one-way classification of stands into moisture-classes should be used

cautiously.

Another difficulty in meeting study requirements during

stand selection was caused by the restrictive nature of the

stand selection criteria. In general, only a subset of the

selection criteria could be satisfactorly met in any given

stand. Finding stands that were over 40 ha; could be walked

to from a vehicle in less than 30 minutes; were free from

previous management activity; had no management activities

planned during the 3-yr sampling period; were not close to

large, noisy streams where bird calls could not be heard;

were accessible from roads that were free of snow in the

spring; and met age- and moisture-class requirements was

generally not possible. As a result, logistic criteria often

outweighed criteria formed by the research questions. Some

stands had to be selected that were not optimal in terms of

stand structure, homogeneity, freedom from past human

activity, or site moisture conditions. The major effect of this

problem was an unbalanced design in terms of the five

age-moisture classes. These problems did not appear to

seriously bias the range of age and moisture conditions

sampled, however.

Locating large stands that fit only within one plant association or moisture-class was often not possible. Most plant

community classifications in the region have been based on

500-m2

 plots rather than entire stands. At the time of stand

selection, little information was available about the spatial

properties of regional plant associations at larger scales. For

example, during stand selection, very dry and very wet sites

were often found to be small in extent and typically embedded within a matrix of wetter or drier conditions. The large

size of the sampling area (relative to the scale of the plant

associations) required the somewhat subjective approach of

considering topographic position and coarse-scale physiographic features in conjunction with vegetation to select large

areas that fell into one of three moisture-classes-wet, mesic

(or moderate), and dry.

The sample size problem was generally not as severe for

the three age-classes-old growth, mature, and young. Disturbed forests in the southern areas, parts of the Oregon

Coast Range, and dry sites in general often contained a

greater mix of age-classes than desired, however. In areas

where the landscape was more of a natural mosaic of

age-classes, stands were located in areas where aerial

photographs and ground truthing indicated that one age-class

was predominant and contrasts between age-classes were

minimal. Although the “search image” for study stands was

for uniform age-classes and structural patches, some mixed

age-classes were included in the sample if they were typical

of the landscape or site moisture conditions.

Despite some difficulties in implementing the sampling

design, the stand selection process was considered to be

generally successful in meeting Program goals. A wide

range of old-growth stands, on different sites, with different

structures and stand histories was sampled. Although more

variability was encountered in site conditions of mesic young

and mesic mature stands than originally intended, measures

of site and environment (understory vegetation) indicated

that no major differences exist along the age gradient of

stands that would invalidate comparisons based on

age-related characteristics.

The T-matrix concept provided a framework for stand

selection and data analysis but was not considered a prescription for strict application of ANOVA models in statistical hypothesis testing. The stand selection and ecological

survey was well suited to gradient analyses and regression

approaches in an exploratory sense. The use of age- and

moisture-classes to investigate ecological relationships

should be viewed as a coarse-scale gradient analysis rather

than an analysis of replicates of discrete forest types.

Although classifications into broad types were useful for

simplifying the results and transferring them to managers

who often have to deal with simplified forest response units,

gradient and regression analyses were most useful for

understanding the details of successional relationships.

Pilot Studies of Vertebrates

Pilot studies of vertebrate sampling methods were conducted

in 1983 on the Wind River Experimental Forest in the

Southern Washington Cascade Range and on the H. J.

Andrews Experimental Forest in the Oregon Cascade Range.

15
Various techniques were evaluated for sampling different

segments of the vertebrate communities. Sampling protocols

(on file at the Forestry Sciences Laboratory in Olympia,

Washington) were developed for aquatic amphibians (stream

surveys), terrestrial amphibians (time-constrained searches of

the forest floor and pitfall traps), forest-floor small mammals

(snap-trapping and pitfalls), squirrels (tracking stations), bats

(ultrasonic recording of echolocation calls), and small, diurnal

forest birds (point counts and foraging observations). We

were unable to develop practical methods for conducting

extensive surveys of raptors or medium- to large-sized

mammals. Reptiles proved to be rare in the forests, and we

did not study them. Evaluations of these and other techniques

are being published elsewhere (Carey and Ruggiero, in press).

Plant Community Studies

The scale of community and age-class patterns posed sampling problems for vegetation studies that could not be

adequately addressed within the research schedule because

we did not conduct vegetation pilot studies. For example,

although sampling design of the vegetation studies appeared

to be adequate for the overstory tree component (five O.l-ha

plots 100 to 150 m apart per stand), how well this design

would sample low-density structures such as large snags was

not known. During the first field season, some sampling tests

were undertaken, and minor modifications were made to

vegetation sampling during the next and final field season,

such as doubling the plot size for large snags.

Conducting a detailed community survey of mosses and

lichens was not possible. Common species were identified

but many less-common species required more time and

taxonomic skill than was available in this rather extensive

survey. In addition, many mosses and lichens inhabit tree

canopies and could not be adequately sampled. Foliose

canopy lichens, such as Lobaria spp., that had fallen to the

forest floor were tallied in ground cover vegetation surveys,

however. Hypogeous fungi were not sampled during the

plant community study because of the seasonality of the

fungi and the effort required to identify genera and species

in a large survey.

Vertebrate Community Studies

Because of funding constraints, the Northern Cascade Range

province was not sampled. The community studies were implemented as planned in the remaining four provinces with

only a few exceptions. Because of both funding and logistical constraints only one replicate of the study design (15

stands) was sampled in the second year in the Oregon

Cascade Range, and bat communities were studied only in

the southern Washington Cascade Range and Oregon Coast

Range.

In addition, gathering observations of foraging birds required

much more time than expected. As a result, these data were

only recorded incidentally, which resulted in insufficient data

for analysis. Similarly, because relatively little data was collected on squirrels from tracking stations, these results are

also not reported here.

Vertebrate community studies were implemented in the

Southern Washington Cascade Range, Oregon Cascade

Range, and Klamath Mountains and, in part, the Oregon

Coast Range in 1984. Studies were continued in the Southern

Washington Cascade Range, Oregon Cascade Range, and the

Klamath Mountains, and fully implemented in the Oregon

Coast Range in 1985. Community studies ended in 1985 in

the Southern Washington Cascade Range, Oregon Cascade

Range, and Klamath Mountains, and in 1986 in the Oregon

Coast Range.

Insular Ecology Study

This study was not conducted because of funding constraints.

Species-Specific Studies

Major research efforts were initiated on the marten and on

arboreal rodents that are important prey species of spotted

owls. Brief descriptions of these studies are provided by

Biswell and Carey, Biswell and others, Center and others,

Corn and Witt, Gillesberg and Carey, and Jones and others in

the Poster Abstracts section of this volume. Ma’or findings

of these studies will be reported elsewhere.

16