Pacific Northwest

Research Station

Fire History and Pattern in a

Cascade Range Landscape

General Technical

PNW-GTR-254

May 1990 Peter H. Morrison and Frederick J. Swanson
Authors PETER H. MORRISON is currently a forest ecologist, The Wilderness Society,

1424 Fourth Avenue, Suite 816, Seattle, WA 98101. At the time the work was done,

Mr. Morrison held various positions with the USDA Forest Service, Oregon State

University, and University of Washington. FREDERICK J. SWANSON is a research

geologist, USDA Forest Service, Pacific Northwest Research Station, Forestry

Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, Oregon 97331.
Abstract

Summary

Morrison, Peter H.; Swanson, Frederick J. 1990. Fire history and pattern in a

Cascade Range landscape. Gen. Tech. Rep. PNW-GTR-254. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

77 p.

Fire history from years 1150 to 1985 was reconstructed by analyzing forest stands in

two 1940-hectare areas in the central-western Cascade Range of Oregon. Serving as

records for major fire episodes, these stands revealed a highly variable fire regime.

The steeper, more dissected, lower elevation Cook-Quentin study area experienced

more frequent fires (natural fire rotation = 95 years) that were commonly low to moderate in severity. The Deer study area, with its cooler, moister conditions and gentler

topography, had a regime of less frequent (natural fire rotation = 149 years), predominantly stand-replacement fires. Fires created a complex mosaic of stands with variable date and severity of last burn. Fire-created forest patches originating in 1800-

1900 are mostly less than 10 hectares. Since 1900, very little of the study areas

burned, possibly because of fire suppression. Old-growth forest conditions have

persisted on some sites through numerous fires and over many centuries.

Keywords: History (fire), patch dynamics, old-growth forest, wildfire fire ecology.

Fire history from years 1150 to 1985 was reconstructed by analyzing forest stands in

two 1940-hectare areas in the central-western Cascade Range of Oregon. The purpose of this study was to understand the natural regime of wildfire, the dominant,

natural disturbance process in this area. This understanding can serve as a reference point for interpreting the effects of forest management practices on the patterns

of forest vegetation across the landscape. Altered landscape patterns of forest cover,

whether by wildfire, management activities, or other processes, can profoundly affect

wildlife, drainage basin hydrology, and characteristics of large-scale ecosystems.

Based on tree-ring records observed on stumps in clearcuts and road rights-of-way,

the records of major fire episodes revealed a highly variable fire regime. Some sites

burned at a 20-year frequency, and others had not burned for over 400 years. The

Cook-Quentin study area, which is the steeper, more dissected, lower elevation site

of the two areas, experienced more frequent fires (natural fire rotation = 95 years)

that were commonly low to moderate in severity. The Deer study area, which has

cooler, moister conditions and gentler topography, has a regime of less frequent

(natural fire rotation = 149 years), predominantly stand-replacement fires. Fires have

created a complex mosaic of stands with variable date and severity of last burn.

Patches originating from fires from 1800 to 1900 are mostly less than 10 hectares,

although burning in a single fire episode could be widespread, as is indicated by

common fire episode dates at sites separated by 10 kilometers.

Fires have not been uniformly distributed through time. Fires were uncommon between about 1580 and 1650 in both areas and from 1580 to 1800 in Deer study area

for unknown reasons. Since 1900, very little of the study areas burned, possibly

because of fire suppression. The frequency of documented lightning-set fires indicates that lightning was a sufficient source to account for the observed fire record.

Indians living in the area may also have been a source of ignition in the presettlement period.
At least two fire regimes were observed in these two study areas. The higher elevation, low relief Deer study area experienced more infrequent, high-severity fire. A

more widespread pattern found in both the Cook-Quentin study area and a broader

area of reconnaissance study revealed a fire regime with more frequent, more low to

moderate severity, and patchier fire than previously recognized. As a consequence of

this fire regime, some forest areas at both stand (1 hectare) and landscape (hundreds

of hectares) scales have sustained old-growth characteristics through numerous fires

and over many centuries.

Contents 1

2

4

7

7

7

8

12

12

12

12

15

15

19

38

50

52

54

64

66

66

69

70

71

72

73

73

74

introduction

Fire and Fire History Research in the Cascade Range

Description of the Study Areas

Methods

Hypotheses and Study Design

Field Data Collection Techniques

Assessment of Scar Record

Accuracy of Tree-Origin Dates

Collection of Site Information

Sample Size and Distribution

Data Analysis

Results

Fire History

Spatial Distribution of Fires

Human Influences

Temporal Distribution of Fires

Results from Intensive Study Sites

Patch Characteristics and Fire-Severity Analysis

Analysis of Fire History in Relation to Aspect and Elevation

Discussion

Comparison of the Fire History of the Two Study Areas

Fire History Scenarios for Old-Growth Stand Initiation

Persistence of Old-Growth Forests in the Natural Fire Regime

Human Influence on the Fire Record

Conclusions and lmplications

Acknowledgments

English Equivalents

References
Introduction Wildfires have been a major, natural disturbance in the forest landscape of the

central-western Cascade Range of Oregon. Viewing the landscape from a high point,

one can see that fires of variable intensity and areal extent have created a complex

mosaic of forest patches. In the past, fire was an integral part of the ecosystem,

affecting wildlife habitat, forest stand dynamics, soil properties, and watershed

hydrology. Fire suppression since the turn of the century and logging since about

1950 have changed the extent and role of fire in this landscape.

The tree-ring record of forests in this area embody the history of fires over the last

800 years. The time is now optimum for reading this record-over the past several

decades about 30 to 40 percent of the central-western Cascade Range has been

clearcut, so the tree-ring record can be observed readily on the surfaces of stumps.

Only in the oldest of these clearcuts have the stumps decomposed so that the record

is becoming lost. The geographic pattern of forest age-classes before cutting can be

interpreted from aerial photographs predating significant logging.

We undertook this study to capitalize on the opportunity to interpret the record of

forest history before it is lost and to establish an understanding of the natural disturbance regime of these forests. Knowledge of natural forest dynamics serves as a

useful reference for evaluating the effects of forest management practices on all

aspects of ecosystem structure and function.

In this study, we examined the natural characteristics of fires, including their frequency, severity, and geographic patterns over the last 800 years. This work began

with a reconnaissance study of forest history in a 490-square-kilometer (km2

) area of

forest land east of Eugene, Oregon (fig. 1). This preliminary study revealed a forest

of very complex structure resulting from a complex fire regime. The great complexity

of the forest fire history led to the detailed study of two 1940-hectare (ha) areas

reported here. These two areas lie within the large reconnaissance study area and

represent the range of fire regimes in terms of frequency, areal extent, and severity

of burning.

Examination of this fire history leads to questions about human impacts on fire and

about implications of the historical fire regime for forest management. The roles of

native people and white explorers, trappers, and ultimately settlers in the area must

be addressed in interpreting periods of high and low fire frequency. In this study, the

processes we found to be responsible for the origin and maintenance of old-growth

forest conditions, which are widespread in this landscape, are counter to what our

understanding was at the beginning of the study. These new insights can guide

future forest management.
i

I \

OREGON

N

STUDY AREA

Figure l-Location of study areas.

Fire and Fire History

Research in the

Cascade Range

Forest fire has been one of the primary disturbance mechanisms affecting natural

forests in the central-western Cascade Range of Oregon for at least 10,000 years.

Charcoal layers are present throughout a core of Wolf Meadow (in the eastern part of

the study area) with some charcoal streaks below Mazama ash (6,700 years before

present). Forest fires in the Cascade Range have been observed and recorded since

at least 1850 (Burke 1979, Martin and others 1976, Plummer 1903). Throughout the

area, charred bark and fire scars are found on surviving conifers. Charcoal is on the

forest floor and in upper soil horizons at most sites. Burke (1979) summarizes written

records of the extensive history of fires in the central-western Cascade Range. A

series of previous studies records an apparent decrease in natural fire size and severity and an increase in frequency along a transect extending from Mount Rainier to

northern California.

The fire history of Mount Rainier National Park was documented by Hemstrom

and Franklin (1982). They describe a fire regime of infrequent, widespread, standreplacement fires as characteristic of the park. The study was based primarily on

stand age data from increment core samples. A natural fire rotation of 465 years is

estimated for 1200-1850.

2
The fire regime recorded in old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.)

Franco) (scientific names of plants are from Hitchcock and Cronquist (1973)) forests

northeast of Mount St. Helens includes large stand-replacement fires and relatively

frequent, low-severity fires (Yamaguchi 1986). The fire frequency of these lowseverity fires was one fire per 40 to 50 years during the first 150 years of stand

development and one fire per 125 to 150 years thereafter.

In a study of the developmental history of dry, coniferous forests in the centralwestern Cascade Range, Means (1981) observes a mean fire interval of 103 years

for all dry-site plots and a mean fire interval of 144 years for all plots in the western

hemlock (Tsuga heterophylla (Raf.) Sarg.) zone. Many of Mean’s study sites are

within 10 km of areas considered in this study.

Stewart (1984, 1986) describes the forest structure of the western hemlock-Pacific

silver fir (Abies amabilis Dougl. ex Forbes) transition zone at 10 sites, 7 km northwest of the Cook-Quentin study area. He notes 15 fires over an interval of 750 years

and concluded that periodic fires of variable severity and extent create an age-class

patch mosaic. He found both multiaged and even-aged stands. Many of his fire dates

correspond closely with those found in this study.

In the Klamath Mountains, further south, Atzet and others (1988) report fire frequency

ranging from 15 to 50 years in series of sites extending from the Ashland watershed,

westward through the Kalmiopsis Wilderness. Individual fires in this area ranged from

severe to light, as evidenced by the spatial complexity-of burn severity in the 1987

Silver Complex Fire. I

These studies and unpublished observations suggest a general pattern of increased

frequency and decreased severity of natural fires from north to south down the Cascade Range to the Klamath Mountains in southwest Oregon. The areas examined in

this study lie midway in this gradient and include sites with quite varied fire regimes.

In addition to these natural fire patterns, the fire regime of the Pacific Northwest in

this century has included 10 000+ ha human-caused, stand-replacement fires. Some

of the extensive areas burned by the initial Yacolt (1902) and Tillamook (1933) fires

(Moms 1934) were subsequently reburned. Reestablishment of trees was consequently suppressed by severely limited seed source, brush establishment, altered

soil-nutrient status and microbiology, and possibly other effects. Portions of these

burned areas are requiring many decades for successful reforestation, despite

intensive management efforts.

In the initial reconnaissance study area, several medium-size, stand-replacement

fires caused by human activity have been documented in the early part of this century (Burke 1979). In 1911, the Seven-Mile Fire (8 km north of the Cook-Quentin

study area) burned about 1500 ha in one stand-replacement patch (Burke 1979).

This area had previously been burned in 1885 and 1897 and partially burned in 1936

(Burke 1979, Plummer 1903). Immediately north of the Cook-Quentin study area is a

250-ha patch burned by a stand-replacement fire in 1911. Directly south of the Deer

study area, the predominantly stand-replacement Carpenter Mountain Fire (1912)

burned about 400 ha.
Description of the

Study Areas

Locatlon and physlography-The reconnaissance study area is in the Willamette

National Forest. The area includes some private timberland and portions of the

McKenzie River and South Santiam River watersheds. The two areas that were

selected for more intensive analysis are centrally located in the reconnaisance area

(fig. 1), and each covers 1940 ha.

Both study areas are at mid-elevation in the central-western Cascade Range and

within major south-draining watersheds. The Cook-Quentin study area (fig. 2) consists of steep, dissected topography with deep, V-shaped valleys and sharp ridges.

This topography developed predominantly through the influence of mass wasting,

surface erosion, and fluvial erosion. Glacial activity played a minor role. The elevation

of Cook-Quentin study area ranges from 524 meters (m) above sea level along Blue

River to 1295 m in the northwest corner of the study area with an average elevation

of about 820 m.

The Deer study area (fig. 3) consists of more gentle topography with broad valleys

and ridge tops. Pleistocene glaciers sculpted these landforms and mass wasting;

surface erosion and fluvial erosion have also been important. The elevation ranges

from 914 m on Deer Creek to 1832 m at the summit of Wildcat Mountain, and the

average elevation is about 1220 m.

N

A

i, y

Contour interval = 80 I

Figure 2-Topographic map for the Cook-Ouentin

study area.

Figure 3-Topographic map for the Deer study

area.
Climate-The maritime climate of this area is characterized by wet, relatively mild

winters and dry, cool summers. At a meteorological station in the adjacent H.J.

Andrews Experimental Forest, annual temperatures average 9.5 ‘C at 430 m elevation. Annual precipitation averages 2400 millimeters (mm) with more than 70 percent

falling between November and March in prolonged periods of rain and snow. July,

August, and September may be entirely rain free, and periods of 60 days without rain

are common. Precipitation in this area is markedly affected by elevation; 1500 m

elevations receive 30 to 40 percent more precipitation than 600 m elevations. A permanent winter snowpack occurs above 1000 to 1200 m elevation; below these elevations, snowpack is sporadic (Waring and others 1978).

The Deer study area probably receives more precipitation than the Cook-Quentin

study area because of elevation differences. A winter snowpack persists into the

spring in much of the Deer study area, affecting fuel and soil moisture in the early

summer.

Forest fire initiation and spread are promoted by several climatic factors. Summer

thunderstorms occur on the average of only 7 days a year but caused over 60 percent of the fire ignitions recorded in recent years (Burke 1979). A seasonal water

deficit occurs during the summer because of low precipitation, high temperature, and

high potential evapotranspiration. Periodic, summer, east winds bring dry air from the

high desert east of the Cascade Range, and relative humidity can drop to 10 percent

or less (Waring and others 1978). Topographic and convective winds during warm,

dry periods are locally important in the spread of fire.

Vegetation-The forest vegetation in the central-western Cascade Range is divided

into two major vegetation zones: the western hemlock zone (300-1050 m elevation

range) and the Pacific silver fir zone (1050-1550 m) (Franklin and Dyrness 1973).

Both zones, as well as a transition zone, are represented in the Cook-Quentin study

area, but only the transition zone and the Pacific silver fir zone are present in the

Deer study area. The uppermost elevations of Wildcat Mountain in the latter study

area are representative of the mountain hemlock (Tsuga mertensiana (Bong.) Carr.)

zone (Dyrness and others 1974).

Within the western hemlock zone, the principal seral tree species is Douglas-fir. Western white pine (Pinus monticola Dougl. ex D. Don), incense-cedar (Calocedrus decurfens (Torr.) Florin.), and sugar pine (Pinus lambertiana Dougl.) are occasional seral

species. Plant associations of the western hemlock zone found in the Cook-Quentin

study area range between Douglas-fir/oceanspray (Holodiscus discolor (Pursh)

Maxim.) and western hemlock/rhododendron (Rhododendron macrophyllum D. Don

ex G. Don)-Oregon oxalis (Oxalis oregana Nutt.). Western hemlock and western

redcedar (Thuja plicata Donn ex D. Don) are tolerant, climax species that may occupy a site with Douglas-fir immediately after a disturbance or invade 50-100 years

later (Dyrness and others 1974, Franklin and Dyrness 1973, Zobel and others 1976).
The Pacific silver fir zone is characterized by climax dominance of Pacific silver fir.

Western hemlock and western redcedar are minor climax species. Plant associations

of the Pacific silver fir zone commonly found in both study areas include the Pacific

silver fir/vaniIlaleaf (Achlys triphylla (Smith) DC.) and Pacific silver fir/coolwort foam

flower (Tiarella trifoliata L.) associations. After a disturbance, Douglas-fir and noble fir

(Abies procera Rehd.) are prominent seral species. Western white pine is an occasional seral species and western hemlock may become established at the time of

disturbance or develop later under a forest canopy (Dyrness and others 1974,

Franklin and Dyrness 1973, Zobel and others 1976).

Forest vegetation is essentially continuous across both study areas. Small areas of

talus, rock outcrops, and wet areas form very localized barriers that may impede the

spread of some fires. Sitka alder (Alnus sinuata (Regel) Rydb.) communities exist in

the Deer study area on several level sites with heavy snow accumulation and abundant seepage water and on steep, snow avalanche tracks; these communities may

impede the spread of fire. Several wet and dry meadow communities are present in

the Deer study area on flats and south-facing slopes. Fire may be impeded by wet

meadow and bog areas but spread readily through the dry meadow communities,

enlarging these meadows. Subsequent reinvasion of dry meadows by trees has been

observed (Hickman 1976).

Nonfire disturbances-Nonfire disturbances can be considered in terms of their

distinctiveness from fire on spatial and temporal levels and their relative importance

as forest disturbances. High wind can cause blowdown of individual trees, groups of

trees, or small stands. Although substantial damage to stands from blowdown has

occurred in the Oregon Coast Range near the Columbia River and in the western

foothills of the Oregon Cascade Range, little extensive damage has been observed

in the interior portions of the western-central Cascade Range (Lynott and Cramer

1966, Orr 1963).

During the 1962 Columbus Day storm that caused extensive blowdown in parts of

the Pacific Northwest, only a few small scattered patches of light blowdown (less

than 1.5 to 6 ha per km2) were observed in the central-western Cascade Range of

Oregon (Orr 1963). Scattered blowdown of individual trees did occur in the study

areas during this storm. Blowdown of old-growth forests along clearcut margins has

been observed in the nearby H.J. Andrews Experimental Forest (Gratkowski 1956);

this phenomenon was also observed during fieldwork near Wolf Meadow in 1976,

but no evidence of extensive patches of blowdown was found.

In natural forests of the study areas, blowdown appears to be a spatially diffuse disturbance of primary importance at the levels of individual trees and small groups of

trees. Fire boundaries may be enlarged somewhat by blowdown, but the presence of

numerous snags probably ameliorates the effect of opening the canopy. Regeneration resulting from wind storms is differentiated from fire regeneration by the low

abundance of early seral tree species in areas disturbed by wind storms.

6
Methods

Hypotheses and

Study Design

Field Data Collection

Techniques

Although insect outbreaks are common east of the Cascade Range and cause extensive damage to timber stands, they rarely cause such damage in the western

Cascade Range (Childs and Shea 1967, Rudinsky 1979, Wickman and others 1973).

In the western Cascade Range, Douglas-fir beetle (Dendroctonus pseudotsugae

Hopkins) damage may occasionally be important to individual trees but is not considered significant to stands. Douglas-fir beetles can infest individual trees that have

been damaged by windthrow, snow breakage, or fire and can lead to mortality. This

mortality is a secondary effect of the initial disturbance.

Disease outbreaks may cause small patches of mortality. Some stands in the H.J.

Andrews Experimental Forest and elsewhere in the central-western Cascade Range

are infected by (Phellinus weirii (Murr.) Gilbertson) (Boone and others 1982, Cook

1982). Disturbance patches resulting from Phellinus infection are easily identified by

their unique morphology and by the persistence of the infection.

We conducted the study to quantify the magnitude and frequency of forest fires in the

central-western Cascade Range. We assumed that forest stands in this region were

predominantly even-aged, representing regeneration after infrequent, high-severity

fires covering large areas. The study was designed to sample an area larger than the

area of one or two fires, so that a few fires would not dominate the record.

Field samples of tree and scar ages were used in conjunction with interpretation of

aerial photography to map forest age-classes similar to the work of Heinselman

(1973). Analysis based on this design indicated that a more complex, fine-scale mosaic of stands existed than had been originally assumed. Also, many fires of variable

severity had produced multiaged stands. Additional sampling was undertaken in the

two small study areas reported here to better quantify the frequency and intensity of

fire.

Stumps in clearcuts, partial cuts, and road rights-of-way were sampled. Increment

cores of live trees were taken to establish tree age in areas where stumps were not

available. At each sample site, a quick survey of the available stumps was made to

locate stumps with scars and obtain an impression of the diameter classes present.

Early seral tree species were generally chosen for sampling. The total tree age at the

time of harvest was estimated by counting annual growth rings. A hand lens was

used to count narrow rings. The height of the stump or the increment core, diameter

of the tree at stump or core height, average width of the innermost rings, and species

were recorded.

All scars, shakes (ring delaminations), and dramatic and abrupt periods of growth

suppression or growth release were noted. Throughout this report, these scars and

related phenomena are referred to by scar type. Both the age of scar occurrence and

a description of disturbed annual rings were recorded.
Assessment of

Scar Record

8

Figure 4-Characteristics of classic fire scars

Fire history studies in dry coniferous forests have relied on classic fire scars found

on cat-faced trees (Arno 1976, Arno and Sneck 1977, Dieterich 1980, Tande 1979).

These classic fire scars are occasionally found in the wetter forests of western

Oregon (fig. 4). Classic fire scars are formed by a series of two or more fires. The

first fire kills a large area of cambium under the thin bark of a young tree, and the

bark sloughs off of this area. Scar tissue starts to grow over the wound, but the

cambium under the thin-barked scar tissue is killed by a subsequent fire before the

wound heals over. The second fire leaves some charcoal on the exposed wood of

the initial scar. This process can repeat many times. Trees with classic fire scars

become sensitive recording devices of fire because the relatively unprotected cambium is continually present. Multiple scars, charcoal surfaces, and an open cat-face

are the hallmarks of a classic fire scar. These scars are denoted as scar type 1 in

this study.
Several factors in the central-western Cascade Range cause fire scars to be “buried”

rather than exposed. Because tree growth rates are much higher than in dry coniferous forests, scars heal more rapidly. Fires are less frequent, allowing more time for

an initial scar to heal over before another fire passes through the stand. A third factor

in the balance is that heart rot and other tree diseases are much more active in the

relatively wet and warm climate of the central-western Cascade Range. Fungi usually

cause the early death of most trees that receive massive scars early in their growth.

These young, scarred trees and the few older trees that do develop classic fire scars

have much higher mortality rates than their counterparts in dry coniferous forests

and, therefore, are not in place long as sensitive recorders of fire.

In our study, 88 percent of the tree scars used for reconstruction of fire history occurred after the first 50 years of growth. The thick bark of mature Douglas-fir in this

region usually protects a tree from massive scarring during a fire, and scars that form

from fire are usually small, occurring at the deep furrows in the bark that form as the

bole expands. These scars (fig. 5) usually heal over in 5 to 15 years. Classic fire

scars are rare because their development requires a fire-return interval rate shorter

than the closure rate of the scars and a decomposition rate slow enough that the tree

stays alive--conditions rarely met in the western Cascade Range.

Two types of fire scars in addition to classic fire scars were used in this study. Type

2 scars are large, well-dated scars of probable fire origin covering over 25 percent of

the bole circumference. Type 3 scars are smaller, well-dated scars of probable fire

origin (figs. 5 and 6). The numbering of scar types does not reflect their accuracy or

their utility in reconstructing fire history.

Fire scars

Older bark overlying

bark scar tissue

Charcoal surface

on oldest bark

Figure 5-Small buried fire scars at deep furrows in bark.

9
I-+ “re scar Older bark overlying

re scar -\ bark scar tissue 3d fire scar 2d fi-- ----

Bark scar tissue

Figure 6-Small fire scars on a common radius.

Several characteristics distinguish scar types 2 and 3 from scars of other origin. The

fire scars commonly occur on the uphill side of a tree where fuel accumulations are

greatest and where the turbulence caused by upslope convective winds during a fire

causes more intense heating of the cambium. They usually coincide with grooves in

the bark where insulation is least. One of the most characteristic attributes of scars in

type 3 is their tendency to occur simultaneously at several places around the circumference of a tree (fig. 5). Often, scarring will occur under the thin bark of the healedover scar, and multiple scars will develop along the same radius (fig. 6). These type

2 and 3 fire scars lack charcoal surfaces because no exposed dead wood was present at the time of the second fire. They will also lack an open cat-face.

10
Several other indicators were used to validate the fire origin of type 2 and 3 scars.

The presence of charcoal on bark predating the scar was used as an indirect indicator of fire origin. Uncut stands adjacent to sample sites were examined to confirm the

presence of charred bark and related fire scars. Another reliable field indicator of fire

origin was charred, older bark partially overlying the bark scar tissue (fig. 5). This feature negates bear damage and physical impact as possible scarring mechanisms,

because this older bark would be removed during such disturbances.

Only 12 percent of the scars used in this study were found on trees less than

50 years old at the time of scarring. Only 3 percent were found on trees less than

20 years old. Where these scars were used in reconstructing fire history, additional

scars from the same fire were always present at the site on trees older than 50 years

at the time of scarring, or early seral tree origin dates were present.

Mechanisms other than fire can cause scarring: bears; mass movements of soil,

rock, or snow; and falling trees or snags. Bears can scar young trees, but significant scarring of trees older than 50 years is unlikely. Bears leave claw marks in

wood layers beneath the cambium. These marks, which are several ring widths

deep, can be seen in scars in the field.

Mass-movement scars usually are associated with considerable physical damage to

underlying wood (Morrison 1975). Their association with distinctive landforms and

geomorphic surfaces makes interpretation obvious.

Tree-fall scars often show some damage to the underlying wood. Most commonly,

young trees are damaged by tree fall because of their thin bark and the high density

of snags in young post-wildfire stands. Tree-fall scars are generally narrow. With

trees less than 50 years old, we used only scars covering more than 25 percent of

the circumference (type 2), which is sufficient to rule out tree fall as a cause. On

older trees with narrow scars, several criteria were used to rule out tree-fall: (1) the

presence of bark predating the scar overlying the scar callous tissue, (2) synchronous radii scars, and (3) scars occurring in concave portions of the tree bole.

Fire scars were usually observed in thick-barked conifers such as Douglas-fir, western white pine, sugar pine, and noble fir. Some fire scars were identified in western

hemlock, western redcedar, and Pacific silver fir, which have relatively thin bark. The

fire origin of these scars was inferred at several localities because they coincided in

age with classic fire scars on Douglas-fir in adjacent sites. Scars on western hemlock

and Pacific silver fir were also observed at the edge of recent slash burns; such

scars may record low-severity fire that is not recorded by more fire-resistant trees,

such as Douglas-fir.

Periods of abrupt and sustained growth release and growth suppression can be

caused by fires. Craighead (1927) and Keen (1937) note that severe fires that cause

defoliation lead to abrupt cessation of growth followed by a period of stimulated

growth. Surface fires that do not cause defoliation usually result in growth increase

by eliminating competing vegetation and releasing nutrients from organic matter.

These ring-width abnormalities, poorly dated scars, scars of uncertain origin, and

shakes were noted in the field but not used in the fire history reconstruction.

11
The accuracy of scar dates depends on (1) accuracy of the count, (2) missing or

false rings, (3) accuracy of determining the date of cut of the tree, and (4) ability to

determine the season of the cut or damage event. The accuracy of the count was

estimated to be + 2 years. Missing rings are not common in conifers on the west side

of the Cascade Range’ and are a negligible source of error, but missing rings have

been associated with fire scars in northern European species (Zackrisson 1980).

Because missing rings associated with fire scars have not been reported in studies in

the Western United States (Arno 1976, Arno 1982, Arno and Sneck 1977, Dieterich

1980), we assumed that they contribute only + 2 years of error. Uncertainty of the

harvest date is usually small (1-2 years at most), but it can be + 3 years. The inability

to determine the season of cut or scar formation contributes + 1 years of error. A root

mean square error (the square root of the sum of the square of the individual error

estimates) of + 4 years for scar dates was estimated.

Accuracy of Tree-Origin The accuracy of origin dates depends on both the factors affecting scar dates and

Dates the error that arises in determining tree age at stump height. An error of + 4 years

was attributed to the uncertainty of determining age at stump height. A root mean

square error of + 6 years was estimated for the accuracy of origin dates. Because

the lag in tree establishment after a fire is highly variable, origin dates represent only

an upper limit for the date of a fire.

Collection of Site

Information

Sample Size and

Distribution

Data Analysis

The date of cut for each sample site was obtained from the Willamette National Forest Total Resource Inventory database. Rarely, the date of harvest was based on

observation of logging operations or by bracketing with aerial photography (available

every 3 to 12 years from 1946). The aspect and elevation of each site were obtained

from topographic maps.

Because of inaccessibility, some portions of each study area were sampled less

intensely than other areas. Sample sites, however, were well distributed throughout

each study area (table 1). Sites within a l-km fringe around each study area were

also considered because fires usually extended beyond the study area boundaries.

The sample density for the Cook-Quentin study area was 22.3 origin and scar dates

per square kilometer. In the Deer study area, the sample density was 17.2 origin and

scar dates per square kilometer.

Tree origin dates were calculated by subtracting total ring count and an estimate of

tree age at stump or core height from the cut date. Dates of scars were obtained by

subtracting the ring count from the cut date.

’ Personal communications, Linda Brubaker, 1988. College

of Forest Resources, University of Washington, Seattle, WA

98195.
Table l-Sample sizes in the Deer and Cook-Quentin study areas

Area

Counted origin Estimated Probable fire Total Dates

Sites dates origin dates scar dates dates per site

Cook-Quentin

area 57 252 36 145 433 7.6

Cook-Quentin

area +-l-km

fringe

Deer

area

86 361 46 170 577 6.7

63 184 64 86 334 5.3

Deer

area +-l-km

fringe 75 228 74 102 404 5.4

The estimate of age at stump height was based on the height of the stump and the

width of the innermost rings, with the following equation, based on suggestions from

F.C. Hall:2

AGE = 0.1852 * SH/RW (for RW>2mm) and

AGE = 0.1852 * SH/2 (for RW<=2mm);

where

AGE = age at stump height (years),

SH = stump height (centimeters), and

RW = average ring width inner three rings (mm).

In this paper, the terms “fire” and “fire episode” are used synonymously to refer to

one or more events interpreted as fires that occurred in a short interval. Criteria for

establishing a fire episode were evaluated at three levels: tree, stand, and landscape.

Tree-level criteria were the interpretation of scar and origin dates for both accuracy

and likelihood of creation by fire. A stand-level criterion was based on the redundancy of the tree-level data throughout a stand sample. A landscape-level criterion

was based on the redundancy of stand-level data among several stands with some

geographic continuity. The interpretations made at each level were checked against

observations at the other levels.

The temporal clustering of scar dates and the geographical affinity of sites with these

dates were used to date fire episodes. The presence of corresponding regeneration

dates was also a primary criterion for bracketing a fire date. Because a large spread

of tree ages has been observed in regeneration after some fires (Hemstrom and

Franklin 1982), scar dates were used to estimate dates of fire episodes, based on

the average date of a cluster of scar dates.

2

 Personal communication, Frederick Hall, 1988, Pacific

Northwest Region, 319 S.W. Pine St., P.O. Box 3623,

Portland, OR 97208.

13
The minimum criteria for interpreting the occurrence of a major fire in either study

area follow:

1. Five or more sites had to have scars or regeneration dating from the fire.

2. Both scar and early seral tree regeneration data had to exist for all but the oldest

fires (for which scar data were nonexistent).

3. Only well-dated scars with high probability of fire origin (types 1, 2, and 3) were

used to date major fires. Only type 1 and 2 scars were used on trees that were less

than 50 years old at the time of scarring.

4. A cluster of nearby contemporaneous fire-scar dates must have existed, with

criteria becoming more relaxed in earlier time periods,

During 1800-1900, fire scars had to be present in at least three sites within a 4-year

period. During 1710-1800, three sites had to have scars within a 6-year period, and

during 1600-1710, a minimum of two sites had to have scars within a 6-year period.

Prior to 1600, fire scars were usually present at two or more sites within a 10-year

period, but dating was based more heavily on tree regeneration data.

5. The maximum timespan for including sites with fire scars in a major fire episode

was: 7 years for 1800-1900 and 12 years for 1600-1800.

6. Geographic affinity for most sites that recorded a fire episode had to be established. Sites within 200 m of one another that recorded the same fire were counted

as one site in the evaluation of major fires.

Supporting evidence for all fires was found at sites beyond the study area boundaries. The presence of these data was not a criterion for interpreting the occurrence

of a fire, but adds support to our conclusions. Although evidence existed in both

study areas for numerous smaller fires that burned one or more sites, this evidence

did not meet the above criteria. These apparently minor fires were not considered in

subsequent analysis.

Construction of fire maps and estimation of burn area-Major fire episodes in

each study area were mapped based on the field sampling and interpretation of

five sets of aerial photographs taken between 1946 and 1979 at scales of 1:12,800

to 1:70,000. Burns less than 100 years old were easily identified on the aerial photographs, but older age classes were more difficult to distinguish. In areas with multiple

fires during the 1800-1900 period, stand boundaries could not be distinguished.

The area burned during each fire episode was estimated by two procedures. In the

first, extent of the burned area was determined by clustering sites with a record of

that event. An approximate boundary line was drawn midway between the cluster of

sites and adjacent sites with no record of the fire. Sometimes where fire boundaries

were between stands of distinctly different age, boundary line interpretations were

made from aerial photographs; the area included within this boundary was measured

with a digital planimeter.

14
Results

Fire History

In the second procedure, the approximate area burned was estimated by

A(i) = AT * NS(i)/(NST-NRE) ;

where

A(i) = estimated area burned during the i’ fire episode,

AT = total study area (1940 ha),

NS(i) = number of sites with a record of the i” fire episode,

NST = total number of sites in the study area, and

NRE = number of sites where the record has been erased by later fires.

The accuracy of this technique depends on the number of sample sites and the

randomness of their distribution.

With both area estimation techniques, the accuracy of area-burned estimates decreases as the record at more sites is erased by later burns. This problem is inherent

in all fire history studies based on forest-stand analysis.

The natural fire rotation for various intervals was calculated for each study area as

the length of time necessary for an area equal in size to the study area to be burned

by a series of fires (Heinselman 1973, Romme 1980), based on a mapped reconstruction of the area burned by each fire. For each site, fire frequency was calculated

as the average fire-free interval between 1910 and the earliest fire recorded at a site.

The analysis period ends in 1910 because this date marks the beginning of effective

fire suppression in the study areas (Burke 1979). This estimate of fire frequency is

most meaningful where multiple fires were recorded at one site. The estimate may

overestimate or underestimate the actual fire frequency at sites where the one recorded fire has erased the record of all previous fires.

Determination of fire severity and patch characteristics-In the Cook-Quentin

study area, one recent fire was mapped from aerial photographs with verification

from field samples. Three levels of fire-induced mortality of the previous stand were

mapped: (1) high severity, 70 to 100 percent; (2) moderate severity, 30 to 70 percent, and (3) low severity, <30 percent and some scarring of trees. Boundaries are

often gradational, so interpretation is subjective. Maps were also constructed of both

study areas, depicting areas burned during 1800-1900 with high, medium, and low

mortality from the cumulative effect of several fires. The areas and perimeters of all

the mapped patches were measured with an electronic digital planimeter.

Cook-Quentln study area-Tree origin and scar data were evaluated for each site,

and an interpretation of fire occurrence for the site was made. Comparisons of fire

records between adjacent sites and among ail sites in the Cook-Quentin study area

were used to refine these interpretations. and fire occurrence at each site was

tabulated (table 2).

Eighteen major fire episodes occurred in the Cook-Quentin study area (table 3). All

these fires were recorded at five sites or more except for the 1150 fire, which was

recorded at only three sites. The 1400 and 1150 fires were documented only by origin dates. interpretation of all other fires was based on numerous tree origin and fire

scar dates.

15
Table P-Fire history by site for the Cook-Quentin study area 

FIRE RECORD AT EACH SITE IS AS FOLLOWS: 

0 = TREE ORIGIN DATE(S) 

S = SCAR DATE(S) 

A = BASED ON APPROXIMATE ORIGIN DATE 

___ ________________________________________------------------------------------------------------------------- 

SITE 

1893 18?15 1849 1841 1834 1813 1807 

FIRE EPISODE 

1800 1772 1758 

S 

1703 

0 

: 

0 

0 

0 

0 

0 

: 

0 

0 

0 

1689 1658 1566 1532 1475 1400 1150 

BR06 

BR23 

coo1 

coo2 

coo4 

COO6 

coo7 

COO8 

coo9 

co11 

co20 

co21 

co22 

CO23 

co24 

CO25 

CO26 

CO27 

CO28 

CO29 

co30 

co31 

CO32 

co33 

co34 

co35 

CO36 

co37 

QUO1 

QUO2 

QUO3 

QUO4 

QUO5 

QUO6 

QUll 

:z: 

Q14B 

QU35 

QU37 

9038 

~~2~ 

QU41 

QU42 

$2: 

QU45 

9046 

QU47 

QU48 

QU49 

QU50 

QU51 

91152 

0019 

0020 

0 0 

0 

0 

0 0 

: 

t 

0 

S ; 

S 

0 

0 

S&O 

A 

S&O 

S&O 

0 

t S 

S&O S 

S S&O 

0 

S&O S 

0 

S 

: 

A 

0 

0 

S&O 

0 

S 

S 

0 

0 

S 

S 

E 

S 

S 

S 

S 

0 

S&O 

0 

0 

S 

S 

20 s 

S 

S 

S&O 0 

S 

S 

S 

S 

S 

0 

S 

0 

0 

S 

S 

S&O 

x 

S 

0 

sao 

0 

S 

0 

S 

S&O 

S&O 

0 

S&O 

S 0 0 

0 

S&O 0 

S 0 

0 

S&O 

S 

0 

0 

0 

0 

S 

S&O 0 

0 

S&O 

0 0 

00 

S80 0 

S 

S 

0 

0 

A 

S&O 0 

S 

: 

0 0 

S S S&O 0 

0 

s.so 

0 

0 S 0 

A 

0 

0 

S&O 

s 

S 

0 

S 0 

S80 

S&O 

S 0 0 0 

0 

S 0 

0 0 0 

S SE0 0 

16 
Table 3-Fire chronology for the Cook-Quentln study area 

Mean 

fire 

year Fire episode 

Length of 

episode 

Time since Sites with 

previous record of 

fire fire 

1893 1891-1896 

1855 1852-1857 

1849 1847-l 851 

i841 1839-1845 

1834 1831-1837 

1813 1812-1816 

1807 1805-1810 

1800 1798-l 804 

1772 1770-l 774 

1758 1752-1764 

1703 1699-l 709 

1689 1683-l 695 

1658 1648-1671 

1566 1549-1586 

1532 1511-1545 

1475 1475-l 500 

1400 1380-1410 

1150 1150-l 200 

- - Years - - - 

5 

5 

: 

6 

5” 

6 

4 

12 

10 

12 

23 

37 

34 

25 

:i 

mm- ___-__ Number 

38 

ii 

7 

21 

7” 

28 

&I! 

14 

31 

92 

34 

57 

75 

250 

9 

10 

10 

9 

22 

10 

14 

13 

5 

9 

17 

12 

10 

8 

8 

12 

: 

Table &-Fire chronology for the Deer study area 

Mean 

fire 

year Fire episode 

Length of 

episode 

Time since Sites with 

previous record of 

fire fire 

1897 1895-l 897 P 47 5 

1850 1847-l 854 12 

1838 1836-l 841 5 9 x 

1829 1826-l 833 29 8 

1800 1798-1801 3 36 9 

1764 1757- 1768 11 189 7 

1575 1568-1591 23 28 

1552 1537-l 557 

:i 

37 13 

1515 1490- 1530 40 79 22 

1436200 1415-1455 1164-l 222 40 58236 : 

Deer study area-Thirteen major fire episodes occurred in the Deer study area 

(table 4) based on evidence at five or more sites per episode. The 1515 and 1200 

fires were documented only by origin dates; other fires, however, were represented 

by both origin and scar dates (table 5). 

17 
Table CFlre hlstory by slte for the Deer study area 

FIRE RECORD AT EACH SITE IS AS FOLLOWS: 

0 = TREE ORIGIN DATE(S) 

S = SCAR DATE(S) 

A = BASED ON APWOXIMATE ORIGIN DATE 

SITE FIRE EPISODE 

189: 1578 1864 1850 1840 1829 1796 1769 1575 155” - 1515 1436 1200 

0 

0 0 

0 

0 s A 

A 

0 

SLO St0 S 0 

DE02 

DR11 

DRi2 

DF:iJ 

DRiS 

DRi.5 

DR17 

DF:lE 

DF’i9 

0 0 

S&O 0 

0 

A 

S&O 

A 

A 

0 

A 

A A 

0 

A 

0 5 SL,O 0 s 

0 0 

sto S 

A 

A 

A 

DH27 A 

DE-8 

DC? 

0 

A 

0 

0 

S 0 

A 

0 

0 

0 

s 0 

SLO A A 

DFISZ 

DR54 

DRY5 

DR56 

DR57 

DR58 

DR59 

DRbO 

DWl 

DRbZ 

DR64 

DR65 

DRb6 

DR67 

DR68 

MA08 

MA09 

MA12 

MA13 

SMCE 

SMO4 

WI02 

0 0 

0 

S 0 s 0 

S 0 

0 

0 0 0 

S&O 

S 

S 0 

0 

S 0 

0 

0 

S 0 

0 

A 

A 

A 

S 

S 

S&O 

0 

0 

0 

S 

0 

0 

S&O 

0 0 

A 

5 S&O s :: s 0 

0 

S 0 0 

0 

A 

A 

WI03 

WMOl 

wrlo7 

WMO3 

WRO2 

WE03 

WR04 

WROS 

0305 

0306 

0307 

0 S&O 0 0 

S S S S sto 0 

5 S S S&O S 0 

18 
Table CArea burned durlng fire episodes In the Cook-Quentln study area 

Fire 

year 

l3umed area 

Record’ Area by fire-severity class 

Ratio Planimeter 

method method A 8 C D E F High Medium Low 

_ _ _ _ _ Hectares _ _ _ _ _ _ _ _ _ _ _ _ Number of sites _ _ _ _ _ _ _ _ _ _ _ _ _ Percent- _ _ _ _ _ 

1893 307 351 : 2 3 3 48 0 11 56 33 

1855 347 540 i 5 2 46 1 20 60 20 

1849 360 402 3 3 30 20 

1641 343 386 1 2 

% f 1: 

6 11 

:: 

1634 855 945 

: t 

4 8 28 7 18 ii 

1813 422 565 : 142 36 11 0 ii: 49 

18070 59149 452 320 20 22 9 :32 11 15 0 145 :: 

1772 221 236 I 1 0 3 39 13 20 60 

1758 407 217 1 2 3 3 34 14 11 

Ei 

33 

1689703 666 78. 54915 7 8 21 i :: ;z 41 53 17 2: 

1658 694 700 

3 

1 

z 

1566 706 1116 3 2 1 

9 :: :: 

ii: 

30 

38 

3: 

25 

1532 818 1544 3 3 1 11 38 

1475 1457 - 8 1 1 : 4 41 :“7 

50 

17 137 

1400 1214 - : 8 8 8 8 :: 100 0 

1150 1942 - 100 0 

- = Bum area was not defined by of planimetric method because of small sample size and, in some 

cases, scattered distribution of sites recording the fire year. 

a The record for each fire is listed for: A = sites where fire date is oldest origin date; B = sites with origin 

date only (not oldest); C = sites with origin date and scar date; D = sites with scar date only; E = sites 

with no record of this fire; F = sites where record has been erased by subsequent fires. 

Cook-Quentin study area-None of the fire episodes after 1500 disturbed more 

than 61 percent of the study area (table 6). All of these fires, however, burned areas 

outside of the study area as well. Interpretation of fire severity was made according 

to the following criteria: sites with only scar dates were classified as burned at low 

severity, sites with origin dates resulting from the fire and from the preexisting forest 

were classified as burned at moderate severity, sites with origin dates resulting from 

the fire, but no older origin dates were classified as burned at high severity. Based 

on these criteria, fires in the Cook-Quentin study area were primarily of low to moderate severity. Only the 1689 and 1658 fires burned at high severity through more 

than 50 percent of the sites that recorded those fires. Before 1500, the database was 

insufficient to assess the extent of fires. 

The extent of each major fire was mapped (fig. 7), and a comparison of the estimated area burned during each fire interval was calculated by the ratio method and 

measured by planimeter (table 6). Less than a lo-percent discrepancy between the 

estimates of the two methods resulted. The two methods became more dissimilar 

before 1600 because of record erasure. 

(Text continues on page 38.) 

19 
o -Clue t Studv 

JkOR 

ea 

Flz EPso&-1893 

(18914896) 

KEY 

l Oldest origin date(s) at site 

q Origin date(s) - not oldest 

4 Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 

Figure 7A-Mean year 1893. 

20 
(18524857) 

Figure 7B-Mean year 1855. 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

m Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

zz Burned area I 1 

Scale: 1 Km 

21 
Cook-Quentin Studv Area 

MAJOR FIRE EPISODE-1849 

(1847-1851) 

a Origin date(s) and scar date(s) 

A Scar date(s) only 

() No record of this fire at site 

z Burned area J 
Cook-Quentin Studv Area 

MAJOR FIRE EPISODE-1841 

(1839-1845) 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

5~ Burned area 

Figure 7D-Mean year 1841. Scale: 1 Km 

23 
o -Que t Study 

JkoR 

ea 

F;R; EPISODAE-1834 

(1831-1837) 

KEY 

l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

E Burned area 

Figure 7E-Mean year 1834. Scale: 1 Km 

24 
o -he t Studv A ea 

JkOR Fk~EPISODi-1813 

(1812-1816) 

KEY l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

ZE Burned area 

Figure 7F-Mean year 1813. Scale: 1 Km 

25 
Cook-Quentin Study ea 

MAJOR FIRE EPISOE-1807 

(18054807) 

KEY l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

H Origin date(s) and scar date(s) 

Ir, Scar date(s) only 

0 No record of this fire at site 

- Burned area 

Figure 7G-Mean year 1807. 

N Scale: 1 Km 

26 
KEY l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

m Origin date(s) and scar date(s) 

(1798-1804) A Scar date(s) only 

0 No record of this fire at site 

s Burned area 

Figure 7H-Mean year 1800 Scale: 1 Km 

27 
,____ 

KEY 

0 Oldest origin date(s) at site 

l Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

(177M774) A Scar date(s) only 

0 No record of this fire at site 

G Burned area 

Figure -/l-Mean year 1772. 

Scale: 1 Km 

28 
o -Que t Study ea 

JkoR FiFEPISOE-1758 

(1752-1764) 

Figure 7J-Mean year 1758. 

KEY l Oldest origin date(s) at site l Origin date(s) - not oldest 

n Origin date(s) and scar date(s 

A Scar date(s) only 

0 No record of this fire at site 

Scale: 1 Km 

29 
KEY 

(1699-1709) 

l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

4 Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

ZL Burned area 

Figure 7K-Mean year 1703. 

Scale: 1 Km 
ue t Studv ea 

Flip EPISO~-1689 

(16834695) 

Figure 7L-Mean year 1689. 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

E Burned area 

I 

Scale: 1 Km 

31 
o -Clue t Study ea 

JkOR Flkkk’ISODA;-1658 

(1648-1671) 

KEY l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

m Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 

32 
o -Clue t Studv 

JkOR 

ea 

FIE EPISo&-1566 

(1549-1586) 

Figure 7N-Mean year 1566. Scale: 1 Km 

33 
o -We t Study ea 

JkOR Flk;nEPISO~-1532 

(1511-1545) 

KEY l Oldest origin date(s) at site 

l Origin date(s) -. not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

E Burned area 
Qentin Study Area 

R FIRE EPISODE-1475 

(1445-1500) 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

- Burned area 

35 
KEY 

0 -Clue t Stu y ea 

&R F;RpEPI:Oi%-1400 

(1380-1410) 

l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

m Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

ZE Burned area 

36 
0 -he t’ StUdv 

JkoR Fl%?EPlSODA;-1150 ea 

(II50- 1200) 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

s Burned area 

Figure 7R-Mean year 1150 Scale: 1 Km 

37 
Human Influences 

Deer study area-All fires recorded in the Deer study area burned beyond study 

area boundaries. In the 1500’s, several larger fires with high severity covered most of 

the study area (table 7, fig. 8). Fires during the 1700-1900 period were of mainly low 

to moderate severity and burned small areas. Fires during the 1800’s burned small 

areas in the upper elevations. 

, 

Cook-Quentin study area--Both Euro-American and aboriginal people have influenced fire regimes. After a review of historical documents, Burke (1979) postulated 

an increase in forest fire incidence in the central-western Cascade Range during a 

“Euro-American settlement period” extending from 1850 to 1910 when explorers, 

trappers, miners, sheepherders, and others used the accessible areas of the Cascade Range. 

In the Cook-Quentin study area, fires burned 13 ha per year during this 60-year 

settlement period. Fire occurrence was higher (25 ha per year) in a comparable 

60-year period a century earlier before Euro-American influences (1750-l 810). From 

1810 to 1850 (when aboriginal populations were waning because of smallpox epidemics, and Euro-American influence was minimal) fires burned 54 ha per year in 

the Cook-Quentin study area. 

No clear effect of human influence on the fire regime was seen in this study area. 

The highest fire incidence occurred during the period of least human influence. We 

concluded that in this study area lightning ignition of fire was predominant, and 

human influence was relatively insignificant until fire suppression became effective. 

The variation among the three periods discussed above may well be an artifact of 

randomness of fire occurrence, study area size, and the length of the periods 

evaluated. 

Table 7-Area burned during flre episodes in the Deer study area 

Fire 

year 

Burned area 

Record’ Area by fire-severity class 

Ratio Planimeter 

method method A B C D E F High Medium Low 

1897 

1850 

1829 

1800 

1764 

1575 

1552 

1515 

1436 

1200 

_ _ _ _ _ Hectares _ _ _ _ _ _ _ _ _ _ _ _ Number of sites _ _ _ - - - - - - - - - - percent - - - - _ _ 

154 

277 

277 

251 

287 

234 

971 

743 

1644 

1457 

1942 

101 

321 

315 

368 

369 

1025 

928 

1856 

- 

- 

0 4 58 0 0 

0 

1 3 3 2 54 0 11 

1 1 1 5 54 1 13 

3 4 1 52 2 33 

2 0 1 :51 5 29 

22 3 2 28 79 

8 2 0 i 21 297 62 

18 4 0 0 4 37 82 

3 1 0 2 2 55 50 

5 0 0 0 0 58 100 

20 80 

78 22 

67 22 

25 63 

56 11 

14 57 

18 4 

15 23 

18 0 

17 33 

0 0 

- = Burn area was not defined by planimetric method because of small sample size and, in some cases, 

scattered distribution of sites recording the fire year. 

’ The record for each fire is listed for the: A = sites where this is oldest origin year, B = sites with origin 

year only (not oldest), C = sites with origin year and scar year, D = sites with scar year only, E = sites 

with no record of this fire, F = sites where record has been erased by subsequent fires. 

(Text continues on page 50.) 

4 

3 

38 
k&R FIR&PIsoDE-1897 ee Study ea 

(18954897) 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 
KEY 

iA.bR &EPISODE-,850 

ee Studv ea 

(1847-1854) 

l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 
ee Studv ea 

ii/&R FIR~rEPISODE-1838 

(18264833) 

KEY l Oldest origin date(s) at site l Origin date(s) - not oldest 

w Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

E Burned area 

Scale: 1 Km 

Figure EC-Mean yea; 1838. 

41 
KEY 

0 Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

(18264833) n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 
h&R FIR&ODE-l800 

ee Study ea 

(1798-1801) 

KEY 

l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

z Burned area 

Figure BE-Mean year 1800. 

Scale: 1 Km 

43 
Deer Study ea 

MAJOR FIR&ODE-l764 

(17574768) 

KEY 

() Oldest origin date(s) at site 

@ Origin date(s) - not oldest 

w Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 

Figure 8F-Mean year 1764. 

Scale: 1 Km 
Deer Study Area 

MAJOR FIRE EPISODE-1575 

(1568-1591) 

KEY l Oldest origin date(s) at site 

l Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

E Burned area 

Figure 8G-Mean year 1575. Scale: 1 Km 

45 
Dee Studv ea 

MAJOR FIRi?EPISODE-1552 

(1537-1557) 

KEY 

0 Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

H Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

z Burned area 

Figure 8H-Mean year 1552. 

46 
iA:OR FIR&PISODE-1515 

ee Studv m 

(1490-1530) 

KEY l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 NO record of this fire at site 

= Burned area 
Deer Study ea 

MAJOR FIRkPISODE-1436 

(1415-1455) 

KEY 

l Oldest origin date(s) at site 

+ Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at site 

G Burned area 

48 
ee Studv ea 

;A;,, FIR~rEPISODE-1200 

(1164-1222) 

-- 

KEY 

e Oldest origin date(s) at site 

l Origin date(s) - not oldest 

n Origin date(s) and scar date(s) 

A Scar date(s) only 

0 No record of this fire at sate 

F Burned area 
Deer study area-In the Deer study area, fires burned 7 ha per year during the 

1850-1910 Euro-American settlement period. In the 1750-1810 presettlement period, 

fires burned 11 ha per year. The highest fire incidence (18 ha per year) in this study 

area was during the period with possibly the least human influence (1810-50). We 

concluded that lightning was an adequate source of ignition for the fires recorded in 

these stands and that human ignition was a minor influence. 

Temporal Distribution 

of Fires 

Cook-Quentln study area-The temporal distribution of sites with tree origin dates 

and fire scar dates is depicted in fig. 9. The trend of a diminishing number of sites 

with recorded fires in earlier periods is caused by erasure of record. After we accounted for this trend, establishment of early seral trees and occurrence of fire 

scars on a site-by-site basis were relatively constant through time with a few short 

fluctuations. 

The natural fire rotation was calculated based on the estimated area burned by each 

fire. This natural fire rotation for the 1500-1910 period was 95 years. Because no 

major fire has burned the study area since 1910, the natural fire rotation for 1910 to 

the present is infinite. This may be the effect of fire suppression activities, climate, 

chance, or a combination of these factors. 

For the Cook-Quentin study area, the average fire frequency for all fires at all levels 

of severity was 96 years. Excluding low-severity fires, the average fire frequency was 

150 years. An average of 3.3 fires was recorded per site, and 2.2 forest age-classes 

were found per site. On average, 1.1 low-severity fires were recorded per site. 

Deer study area-Fewer sites in the Deer study area than in the Cook-Quentin 

study area had fire scars and early seral trees dating from 1700-1910 (fig. 10). The 

large number of sites with tree origin dates between 1480 and 1600 reflects more 

extensive fires during this period and less erasure of record by later fires. 

The natural fire rotation for the Deer study area during 1500-1910 was 149 years. In 

this study area, the average fire frequency for all fires of all levels of severity is 241 

years. Excluding low-severity fires, the average fire frequency was 276 years. Per 

site, averages of 1.9 fires of all severity levels, 1.5 age classes, and 0.4 low-severity 

fires were found. 

50 
Number of sites 

with origin dates 

1100 

1120 

1140 

1160 

1160 

1200 

1220 

1240 

1260 

1260 

1300 

1320 

1340 

1360 

1360 

1400 

1420 

1440 

1460 

1480 

1500 

1520 

1540 

1560 

1560 

1600 

1620 

1640 

1660 

1660 

1700 

1720 

1740 

1760 

1760 

1600 

1620 

1640 

1660 

1660 

1900 

1920 

1940 

1960 

! : : : : . . . . 

;:::.. 

F”’ 

i 

;::::. 

,)::::::::::.... 

F 

F-* 

;::::::::...... 

. . . . . . ..*.*......... 

; * l l . . . . . * l 

;::: ::. 

i 

Number of sites with scar dates 

(scar types 1, 2, and 3 only) 

. 

. . 

. 

. 

. 

l . 

l 

. . 

. . 

. . 

at. 

l 

. . 

. . . . . . 

. . . 

l ...* 

l . . ..*....*........ 

. ..**........... 

. ..*....*.....*.. 

**a*. 

.*t.... 

Figure 9-Histogram of number of sites in the Cook-Quentin 

study area with tree origin and scar dates. 

51 
Number of sites 

with origin dates 

1100 

1120 i 

1140 

1160 i* 

1160 

1200 ;: 

1220 1240 :* 

1260 ] 

1260 1300 I 

1320 

1340 i 

Number of sites with scar dates 

(scar types 1, 2. and 3 only) 

1360 1360 : 

l 

1400 1420 !' . 

1440 1460 :** 

1460 

1500 2::: ::: 

1520 i:::::: . 

1540 . . . 

1560 ;::::::z* ..I) 

1560 l 

1600 I**" 

1620 I . 

1640 . . 

1660 1' . 

1660 ;: . 

1700 .*a 

1720 ;: . 

1740 . . . . . 

1760 !:::: ..**, 

1760 . . . . 

1600 . . . . 

1620 

;:::::.. 

. . . . . l . . . 

1640 

1660 

;::::::-•* . . . . . . . . 

1660 i:' 

1;" 

1900 . . 

1920 ] 

1940 ..t 

1960 f 

Figure lo-Histogram of number of sites in the Deer study 

are with tree origin and scar dates. 

Results From Intensive 

Study Sites 

Cook-Quentin study area-This record of fire in the Cook-Quentin study area probably underestimated the frequency of low-severity burns, which did not scar many 

trees. At most sites, only a few stumps were sampled, and a more complex fire 

record might have been found in a larger sample. We used intensive sampling for 

determining if a more complex fire record would become evident with increasing 

sample size. 

52 
1390 

1400 

1410 

1420 

1430 

1440 

1450 

1460 

1470 

1460 

1490 

1500 

1510 

1520 

1530 

1540 

1550 

1560 

1570 

1580 

1590 

1600 

1610 

1620 

1630 

1640 

1650 

1660 

1670 

1660 

1690 

1700 

1710 

1720 

1730 

1740 

1750 

1760 

1770 

1760 

1790 

1600 

1610 

1620 

1630 

1640 

1650 

1860 

1670 

1990 

1890 

1900 

1910 

1920 

1930 

1940 

D 

D 

ED 

DDDD 

D 

D 

H 

DDH 

DDDDDDDDHH 

DH 

DDHH 

HHH 

HH 

H 

Key to origin date codes 

and scar types 

D s Douglar-flr 

23 H = Western hemlock 

2 1 = Welldated classic fire scars. 

2 = Well-dated seers coverlng 

2 

over 25% ring circumference. 

3 3 = Well-dated smaller scars of 

probable flre origin. 

2 L I 

23 

33 

2 

222 

2 

2 

122223333 

i 

133 

3 

2 

1 

3 

Figure 1 l-Histogram of all origin dates and scar dates at 

intensive sites in the Cook-Ouentin study area. 

Forty-six stumps were sampled within a 4-ha area at four adjacent sites in a stand on 

a south slope at about 850 m elevation in the northeast sector of the Cook-Quentin 

study area. We expected this area to have experienced frequent fire. In the interval 

between 1400 and 1940, eighteen decades (33 percent) had at least one well-dated 

probable fire scar (fig. 11). Douglas-fir origin dates were present in 13 decades 

(24 percent). Between 1800 and 1940, there were four positive fire scars and 10 decades with well-dated fire-related scars, ir dicating a possible mean fire interval of 

about 14 years during the 1800-1940 period. 

53 
Intensive-sampling results indicated that the complexity of the fire record observed 

at this site increased as a function of the number of tree-ring histories obtained 

at a site. The original sample of four stumps in this area recorded four major fires. 

Another five major fires were discovered after sampling 42 additional stumps. 

Deer study area-An intensive sample was used to evaluate the effect of sample 

intensity on number of fires detected. In the Deer study area, a sample of 20 trees 

from four adjacent sites in a 6-ha area was taken in an old-growth stand that had 

been clearcut on a gentle northeast slope at 1100 m elevation. Previous sampling in 

the area indicated that the stand had a narrow distribution of ages and had experienced one fire. 

All but one Douglas-fir origin date in this intensive sample occurred between 1560 

and 1590. This narrow age range is likely the result of one major fire, as indicated by 

the original sample of four stumps in this stand. Additional sampling revealed that 

western hemlock was established 50 to 100 years after the last Douglas-fir origin 

date. A few scars of uncertain origin were recorded, but we found no conclusive evidence of low-severity fire in this stand. Increasing the number of samples taken at 

this site did not show an increase in the complexity of the fire record we observed. 

Patch Characteristics 

and Fire-Severity 

Analysis 

Cook-Quentin study area-A map was constructed to depict the complex mosaic 

of patches that resulted from three levels of stand disturbance by a 1893 fire in the 

Cook-Quentin study area (fig. 12). Extensive corridors of low-mortality stands extended through a matrix of stands thinned by a medium-severity fire. Patches from 

high-mortality fire also occurred within this matrix. Of the total area burned by the 

fire, 53 percent was medium mortality, 18 percent was high mortality, and 29 percent was low mortality. 

Patches created in this area by the 1893 fire were numerous and irregular (table 8). 

The patch-irregularity index (ratio of the perimeter of the patch divided by the perimeter of a circle with the same area) was 1.52 for low-mortality patches and 1.33 for 

high-mortality patches. Both low- and high-mortality patches had high densities of 

edge. 

54 
r 

0 

KEY 

q Hlgh Rre mortality 

IEI] Medium Rre mortality 

q Low Rre mortality 

L 

@ Oldest orlgln date(s) at site 

+ Orlgln date(s) - not oldest 

q Orlgln date(s) and acar date(s) 

A Scar date(s) only 

0 No record of MS fire at site 

n* nt 

A 

Scale: 1 Km 

0 

0 

0 

96 

0 

0 

0 

0 

0 

0 

-. Figure 12-Fire-mortality patches for 1893 fire episode in the 

Cook-Quentin study area. 

55 
Table 8-Patch analysis for 1893 fire episode in the Cook-Quentin 

study area 

Patch 

type Area 

Fire 

area 

Mean patch Edge density 

irregularity Total 

index edge Type 1a Type 2b 

km2 percent km km per km2 

Low 

mortality 1 .Ol 29 l.! 2 19.9 5.7 19.7 

Medium 

mortality -1.88 53 - - - - 

High 

mortality 0.62 18 1.33 18.1 5.2 29.2 

Total 3.51 

- = Not determined for medium mortality patches. 

a Total edge per total fire area. 

’ Total edge per total patch type area. 

Small patches dominated the size distribution of high-mortality patches created by 

the 1893 fire (fig. 13). Ninety-six percent of the high-mortality patches were less than 

10 ha and covered 68 percent of the high-mortality area. Although 72 percent of the 

medium-mortality patches were less than IO ha, they accounted for only 5 percent of 

the area of medium mortality. Likewise, 70 percent of low-mortality patches were less 

than 10 ha but accounted for only 19 percent of the area. Nineteen percent of all 

patches were truncated by the boundary of the study area. Aerial photograph analysis of boundaries of patches extending beyond study-area boundaries indicated that 

truncation does not markedly affect the patch-size distribution. 

The patch distribution for the 1800-1900 period in the Cook-Quentin study area represented the cumulative high, medium, and low mortality from all the fires during that 

period (fig. 14). Extensive patches and corridors of low-mortality areas formed a 

complex patch mosaic. Many high-mortality patches of variable size existed amid a 

medium-mortality matrix that covered 42 percent of the study area (table 9). 

56 
80 

It 

_m 70 

0 

!2 6’3-1 

:2 

.g 50 

E, 40 

$2 

a 30 

II I 

20 

10 

0 1 I 20 

10 

0 

~10 20 30 40 50 60 70 80 90 loo 110 120 130 <lO 20 30 40 50 60 70 80 90 100 110 120 130 

Patch size class (hectares) Patch size class (hectares) 

High-mortal&y patches 

100 

90 

80 

2 

m 70 

u 

- 60 

.!Y 

In 50 .E 

5 40 

E 30 

a 

Medium-mortality patches 

Low-mortality patches 

Percent of patcher 

Percent of aresln 

p 70 

u 

0, 60 

IN 

g 50 

‘i 40 

g30 

0. 

20 

10 

0 

-A0 20 30 40 50 60 70 80 90 100 110 120 130 140 

Patch size class (hectares) 

Figure 13---Patch-size distribution for 1893 fire episode in the 

Cobk-Quentin study area. 
Figure 14-Fire-mortality patches for 1800-1900 in the CookQuentin study area. 

58 
Table 9-Patch-analysis summary for 1800-1900 fires in the Cook-Quentin 

study area 

Patch 

type Area 

Fire 

area 

Mean patch Edge density 

irregularity Total 

index edge Type la Type 2b 

km2 percent km km per km2 

Low 

mortality 6.01 31 1.49 10.5 0.54 1.75 

Medium 

mortality 8.24 42 - - - - 

High 

mortality 5.30 27 1.45 94.8 4.85 17.89 

Total 19.55 

- = Not determined for medium mortality patches. 

a Total edge per total fire area. 

b Total edge per total patch type area. 

The average irregularity index for the high-mortality patches was 1.45 and 1.49 for 

low-mortality patches. The total perimeter and edge density were about equal for lowand high-mortality patches. Small patches dominated the size distribution of patches 

as in the 1893 fire; 88 percent of high-mortality patches were less than I0 ha and 

accounted for 31 percent of the high-mortality area (fig. 15). Ninety-six percent of the 

high-mortality patches were less than 30 ha and accounted for 53 percent of the 

area. Two large patches (about 105 ha each) accounted for 39 percent of the area. 

Similar patch-size distributions existed for medium- and low-mortality patches. 

Deer study area-Fires in 1800-1900 burned only 59 percent of the Deer study 

area, forming larger and less complex patches than in the Cook-Quentin study area 

(fig. 16). Much of the Deer study area burned at low severity in this period (table 10). 

Patch-size distribution was similar in many respects to the Cook-Quentin study area, 

but we found fewer patches less than 10 ha (fig. 17). Although 62 percent of highmortality patches were less than 10 ha, they accounted for 17 percent of the highmortality area. Eighty-nine percent of the high-mortality patches were less than 30 ha 

and accounted for 61 percent of the area. Similar patterns were observed for mediummortality patches, Low-mortality patches less than 10 ha were frequent but occupied 

only 6 percent of the area. The shape of high-mortality patches was somewhat less 

irregular than in the Cook-Quentin study area. Low-mortality patches formed the 

matrix in the Deer study area; therefore, they had a higher irregularity index than in 

the Cook-Quentin study area. 

(Text continues on page 64.) 

59 
High-mortality patches Medium-mortallty patches 

'""1 a Pewem of palches 

* 8o 

i-4 70 

3 

2 Q) 60 

.g 50 

E 

g 

40 

& 30 

a 

20 

90 

10 

0 I 

Percent of wea In 

Percent of palches 

Percent of .rem In 

patches 

w 

co 70 

B 

a60 

.!J 

.E 50 

E 40 

ti 

& 30 

a 

20 

10 

0 

Patch size c&s (hectares) Patch size class (hectares) 

Low-mortallty patches 

Percent of palcher 

PelCenl of ama In 

8 

m 70- 

u 

Q 60- 

.! 

z 50, 

‘i 40- 

0 

$ 30- 

n 

20 - 

10 

0 

cl0 20 30 40 50 60 70 80 90 100 110 120 130 

Patch size class (hectares) 

Figure 15-Patch-size distribution for 1800-1900 in the 

Cook-Quentin study area. 
8 High-morlallly patch N 

q Medium-mortality parch 

A 

Scale: 1 Km 

q Low-morlalily patch 

..’ ‘. , :. . . . . 

. ,i ;... 

Y 

. i .-.;. ‘- ;.: 

. . . . 

..~ 

Figure 16-Fire mortality patches for 1800-1900 in the Deer 

study area. 

61 
Table 10-Patch-analysis summary for 1800-1900 fires in the Deer 

study area 

Patch 

type Area 

Fire 

area 

Mean patch Edge density 

irregularity Total 

index edge Type 1a Type 2b 

km2 percent km km per km2 

Low 

mortality 5.02 

Medium 

mortality 3.64 

43 

32 

1.52 51.0 4.4 19.2 

High 

mortality 2.28 25 1.32 39.1 3.4 17.1 

Total 11.54 

- = Not determined for medium mortality patches. 

’ Total edge per total fire area. 

* Total edge per total patch type area. 

62 
High-mortality patches Medium-mortality patches 

Percent of patches 

Percent of area In 

patches 

Percent of petchea 

Percent of area In 

patches 

aI60 

.s 

aJ 60 .p! In u-2 

.E 50 .c 50 

E 840 E 840 

& 30 z 

a 

30 

a 

20 20 

10 10 

0 0 

<lO 20 30 40 50 60 70 80 90 loo 110 120 130 <lO 20 30 40 50 60 70 80 90 100 110 120 130 

Patch size class (hectares) Parch size class (hectares) 

Low-mortality patches 

Percent of patcher 

Percent of mea In 

patches 

ii 60 

.!i 

z 50 

E 

8 

40 

& 30 

a 

20 

cl0 20 30 40 SO 60 70 80 90 100 110 120 130 140 

Patch size class (hectares) 

Figure 17-Patch-size distribution for 1800-1900 in the Deer 

study area. 
Analysis of Fire History 

in Relation to Aspect 

and Elevation 

To assess possible effects of elevation and aspect on fire occurrence, we pooled 

the data from both study areas. We compared the aspect and elevation distribution of 

sample sites with overall distribution for the study areas estimated by a random 

sample of 400 points (tables 11 and 12). A M-square goodness-of-fit analysis 

(Zar 1974) was used to test if the aspect and elevation distributions of the sample 

sites conformed to the expected aspect and elevation distributions of the study area; 

no significant difference was found between the observed and expected elevation 

or aspect distributions (p = 0.05). This implies that the sample sites represent a 

good sample of the study area with respect to aspect and elevation. 

Table 11--Distributions of aspect In study areas based 

on random sample (n=400) and field sample sites 

Aspect 

North 

Northeast 

East 

Southeast 

South 

Southwest 

West 

Northwest 

Ridge 

Valley floor 

Random 

sample 

Percent 

4.0 

8.0 

13.8 

12.5 

14.8 

15.3 

10.5 

5.5 

9.8 

6.0 

Field sample sites 

Number Percent 

4 3.3 

8 6.7 

15 12.5 

16 13.3 

20 16.7 

18 15.0 

13 10.8 

4 3.3 

16 13.3 

6 5.0 

Table 12-Distributions of elevation In study areas 

based on random sample (N=400) and field sample 

sites 

Elevation 

Meters 

<915 

915-1066 

1067-1219 

>1220 

Random 

sample 

Percent 

31.5 

20.0 

18.3 

30.3 

Field sample sites 

Number Percent 

33 27.5 

29 24.2 

27 22.5 

31 25.8 

64 
Although apparent differences existed in various measures of site fire history that 

are dependent on aspect, low sample size in many aspect categories made these 

relations impossible to assess statistically (table 11). Site fire history is somewhat 

dependent on elevation (table 13). A single-factor analysis of variance and NewmanKeuls multiple range test (Zar 1974) revealed that the mean number of age classes 

and low-severity fires were significantly different (p = 0.05) between sites above and 

below 915 m elevation. The average fire frequencies for all fires and for only moderate and severe fires were significantly different between sites above and below 

1067 m. In general, more age classes and more fires occurred at low elevations 

than at high elevations in the study areas. 

Table 13-Analysis of fire history for both study areas in relation to 

aspect and elevation 

Mean fire frequency 

Position 

Age Low-severity 

class fires All fires 

Moderate and high 

severity fires 

Aspect: 

North 

Northeast 

East 

Southeast 

South 

Southwest 

West 

Northwest 

Ridge 

Valley floor 

Elevation (meters): 

<915 

915-1066 

1067-1219 

>1220 

__-_ Mean number _ _ _ _ - - _ _ - _ - Years _ _ _ _ _ _ _ _ _ 

1.50 .75 242 311 

1.88 .50 230 257 

1.40 .53 210 250 

1.88 1.13 120 179 

2.05 1.05 174 221 

1.94 .56 176 192 

1.92 .85 183 270 

2.75 1.25 99 125 

1.81 .25 143 152 

1.67 1 .00 172 281 

2.49 1.42 90 151 

1.83 .76 130 178 

1.30 .37 254 300 

1.71 .35 226 247 

65 
Discussion Because the objective of this study was to provide an extensive sample of fire frequency and severity in the two study areas, a high sample density was more important than high precision with rigorous dendrochronological techniques applied to a 

small number of trees. The sampling for the original reconnaissance study (with a 

sample density of about seven trees per km2) revealed a complex forest history, 

but the sample was inadequate for describing important aspects of fire history in 

the area. The resolution of the fire record was significantly increased by additional 

sampling in the two study areas. Sample density was increased to 14.7 trees per 

km2, one of the highest sampling densities for fire history studies reported in the 

literature (table 14). Nevertheless, because of the complexity of the fire regime, important aspects of the fire history still could not be addressed. Results from intensive 

sites indicate that even higher sampling densities than used in the study can yield a 

more complete fire record on some sites. On sites with one or two fires recorded in 

even-aged stands, little is gained by more intensive sampling. 

In the central-western Cascade Range of Oregon, both frequent low- to moderateseverity fires and stand-replacement fires recurring at intervals of 6 to 800 years 

have been important. The relative importance of fires for each type is unknown. 

Results of this study and the work of Means (1981) and Stewart (1986) indicate that 

frequent, noncatastrophic fire was widespread in the central-western Cascade Range. 

Comparison of the 

Fire History of the 

Two Study Areas 

Many similarities exist in the fire history of the two study areas. During the last 300 

years, only the 1834 fire in the Cook-Quentin study area burned more than one-third 

of either study area. Because all fires in the study areas extended beyond the area 

boundaries, the total area influenced by each fire was not determined. Fire was widespread during many fire episodes. The 1800 fire burned in both study areas. The 

1849 and 1841 fires in the Cook-Quentin study area may be equivalent to the 1850 

and 1838 fires in the Deer study area. Many of these fire episodes were also noted 

by Stewart (1984) in a study area 7 km to the northwest of the Cook-Quentin study 

area. In both study areas, fire was conspicuously absent between 1580 and 1650- 

a period bracketed by fairly high fire activity. 

Table 14-Sampling densities of selected fire history studies 

Study Trees sampled 

no. per km2 

Origin and probable 

fire scar dates Study area 

no. per km2 km2 

Morrison and 

Swanson (this study) 

Hemstrom and 

Franklin (1982) 

Tande (1979) 

Kilgore and 

Taylor (1979) 

Arno (1976) 

Heinselman (1973) 

13.8 19.8 39 

1.3 1.3 770 

8.1 9.6 432 

12.1 36.6 

14.5 ;: 

2 0.9 3480 

66 
High Moderate Low Unburned 

Fire-mortality class 

Figure l&-Comparison of fire-severity distribution for 

patches created from fire during 1800-1900 in both study 

areas. DR = Deer and CQ = Cook-Quentin study areas. 

Several fairly widespread fires burned through both study areas during 1490-1580. 

The number of fires and coincidence in dates between study areas during this period 

are difficult to determine because of the paucity of scar data, but at least three major 

fire episodes occurred in each study area during this interval. These fires mark the 

origin of much of the old-growth forest in the study areas. A few Douglas-fir stumps 

with origin dates between 1150 and 1220 are scattered through both study areas. 

Individual trees and scattered stands of similar age were found in other parts of the 

initial reconnaissance study area, indicating that fire activity was widespread during 

this period. 

Although many similarities exist between the fire history of the two study areas, substantial differences demonstrate significant heterogeneity in the fire history of the 

central-western Cascade Range. For instance, between 1500 and 1910 the natural 

fire rotation for the Cook-Quentin study area is 95 years compared to 149 years for 

the Deer study area. Based on calculated average fire frequencies of 96 years for 

the Cook-Quentin study area and 241 years for the Deer study area, the occurrence 

of fire appeared to be 2.4 times more frequent in the Cook-Quentin study area. 

The 1800-1900 fires caused low mortality in the majority of the Deer study area, although the Cook-Quentin study area experienced mainly moderate mortality (fig. 18). 

Because some evidence showed more extensive fires of higher severity in both study 

areas before 1800 and the fire-seventy distribution may differ considerably from one 

fire to another, the distribution of fire severity cannot be assumed to remain constant 

through time. 

67 
The fire regime of the Cook-Quentin study area was characterized by fairly frequent,

medium- to low-severity fires that have occasionally crowned out and created

patches of even-aged stands; more commonly, these fires have thinned the preexisting stand. The stands that have developed after these fires are generally multiaged with an average of more than two age classes of early seral tree species.

Regeneration from more than four fires was found at 16 percent of the sites.

Fire in the Deer study area was less frequent on the whole. Small fires of medium

to low severity occurred periodically in upper elevation areas and larger, standreplacement fires occurred infrequently. Most of this study area burned at least

once during three fire episodes in 1480 to 1580.

Although the two study areas are in close proximity, some significant environmental,

climatic, and physiographic differences may explain contrasts in their fire history.

Because the Deer study area is at a higher elevation than the Cook-Quentin study

area, it has a colder and wetter climate that may have lead to less frequent fires.

Fuels under these conditions in the Deer Creek area may rarely be conducive to

carrying fire. Fewer microsites of hot, dry fuels may exist in the relatively gentle

topography of this area as compared to the Cook-Quentin study area. On the other

hand, this gentle topography may facilitate the spread of large, stand-replacement

fires when rare favorable climatic conditions prevail. This combination of factors

would result in infrequent, but extensive stand-replacement fires observed in the

lower elevations of the Deer study area.

In upper elevations of the Deer study area, lightning ignitions and exposure to desiccating east winds may be frequent; the resulting fires usually do not spread far

because of the numerous nonforest wet areas. These factors could lead to more

frequent, but less intense fires in the upper elevation parts of the Deer study area.

The complex topography of the Cook-Quentin study area forms many potential fire

boundaries such as stream bottoms, sharp ridgetops, and changes in aspect and

vegetation type. In this irregular landscape, great variation occurs in fuel ignition

potential, rate of combustion, and rate of fire spread. Wind patterns are also highly

irregular in complex topography. These factors alter fire behavior, producing patchy

fires of variable severity.

Fire regime was expected to vary with aspect and elevation. In the data from both

study areas, the low sample size and high variation in several aspect categories

made it impossible to test for significant differences in fire history with respect to

aspect. Low elevation sites burned more frequently than higher elevation sites,

mostly as a result of more frequent low-severity fires.

In both study areas, the fire record shows great variability from site to site. Some

sites burned every 20 years, although others were fire-free for 500 years. This

variability is not explained by a simple analysis of aspect and elevation. A more

complete analysis of topographic position, slope, aspect, and elevation may reveal

relations between fire history and site characteristics that are not apparent here.

68
Fire History Scenarios

for Old-growth Stand

Initiation

Much of the forest of both study areas may be characterized as old-growth Douglasfir similar to old-growth stands found elsewhere in the western Cascade Range

(Franklin and others 1981, Franklin and Spies 1983). The circumstances surrounding

the establishment and growth of these stands provide insight into the dynamics of

old-growth stand development and maintenance.

We propose three scenarios to explain the origin of these old-growth stands. Each

scenario would produce a distinctive signature in the forest age structure and treering record, and examples of each can be found in the old-growth forests of the

Cascade Range.

In one scenario, the fire regime consists of large, stand-replacement fires recurring

every 200 to 400+ years. In this scenario, a fire might cause a pattern of moderate

age-spread of Douglas-fir trees in some stands because of slow restocking, caused

by lack of seed source, brush establishment, and other factors. Site-to-site uniformity

in age structure with some variation related to distance from seed source would be

expected. Fire scars on remnant trees from such an event would yield coincident

dates. Subsequent development of such a stand would be controlled by intertree

competition and mortality from disease, windthrow, and other processes of very local

extent. Release of late seral trees in small gaps created by the above processes

would be an important aspect of stand development. Some fire-sensitive, late seral

trees would approach the age of the Douglas-fir trees. Some of the fires and stands

described by Hemstrom and Franklin (1982) and Juday (1977) may represent examples of this scenario.

In a second scenario, fire regime is characterized by a large catastrophic fire

followed by several reburns within a period of 50 years and then a long fire-free

interval. The age distribution of Douglas-fir trees would be extended as a result of

very slow restocking and patchy burning by the subsequent fires. In this case, the

fire-scar record would yield some evidence of these reburns, and more site-to-site

variation in age structure would be expected. Subsequent development of stands

originating under this scenario would be similar to that described in the first scenario, except that the early development would be marked by substantial mortality

in areas that were reburned. Establishment of fire-sensitive species would postdate

the last reburn, creating more age spread between these trees and Douglas-firs that

may have survived. Examples of this pattern are found in the Tillamook, Yacolt, and

Seven-Mile Burns. Many of the old-growth stands within the Deer study area appear

to have resulted from such a scenario.

In a third scenario, old-growth stands would result from a fire regime of multiple,

patchy fires of varying severity recurring every 20 to 100 years. Narrow age spread

of Douglas-fir trees in stand replacement patches would be caused by rapid regeneration made possible by abundant surrounding seed source. Very wide age spread of

Douglas-fir trees within other stands would result from repeated low- and moderateseverity burns and subsequent regeneration. Development of such a stand would be

controlled to a large extent by the thinning effects of low- and moderate-severity

burns. Intertree competition and mortality from disease, windthrow, and other smallscale disturbances would also play important but diminished roles. Fire-sensitive

species would be less abundant and markedly younger in such stands compared to

69
stands operating under the first two senarios. Establishment of new Douglas-fir trees

in gaps created by thinning fires would be an important aspect of stand development.

A complex fire-scar record extending over many centuries would be a signature of

this scenario. Most of the old-growth stands in the Cook-Quentin study area appear

to have resulted from such a scenario.

Key to evaluating the fires that controlled establishment of old-growth stands was the

fire-scar record found in the few trees older than 450 years. Evaluation of this information in the two study areas and in the large reconnaissance study area suggested

that examples of each scenario may be found in the central-western Cascade Range.

The first two scenarios were more prevalent in the rolling upland areas, and the third

scenario was more prevalent in more dissected topography.

Persistence of

Old-Growth Forests

in the Natural Fire

Regime

Many old-growth stands in both study areas have persisted through low- to moderateseverity fire. At 8 percent of the sites in the two study areas with old-growth trees

(over 200 years old), a forest canopy persisted and stand-replacement fires were

absent for at least 750 years. At 95 percent of the old-growth sites in the CookQuentin study area, a forest canopy persisted through low- to moderate-severity fires.

In the Deer study area, a forest canopy remained through low- to moderate-severity

fire at 52 percent of the sites with old-growth trees. This persistence of old-growth

forest conditions despite repeated under burns has been observed elsewhere in the

Pacific Northwest (Juday 1977; Means 1981; Stewart 1984, 1986; Yamaguchi 1986).

The physical characteristics of old-growth Douglas-fir stands explains their ability to

withstand repeated fires. The height of the trees and the concentration of foliage in

the upper 50 percent of the bole (above 25 m in height) make crown fires less probable because sufficient heat cannot easily reach the canopy to ignite the crowns.

Where a fuel ladder is present, the crowns may ignite in patches. Thick bark and

extensive root mass in mineral soil are other fire-resistant characteristics of oldgrowth Douglas-fir trees.

Little attention has been given to the role of under burns in old-growth Douglas-fir

ecosystems. These fires influenced succession in some areas by periodically removing fire-sensitive, late-seral species, and they may be one factor in the long

timelag before dominance is attained by climax species. Under burns undoubtedly

added complexity to the structure of some old-growth Douglas-fir forests. On many

sites in the study areas, new early seral trees established after low- to moderateseverity fires. These new trees grew in canopy openings in the thinned old-growth

forest and lived to develop old-growth characteristics while their predecessors still

form a significant component of the stand. Live old-growth trees, large snags, large

logs, and high structural complexity may have been sustained in many sites for

nearly 1,000 years under the natural fire regime. This pattern is radically different

from the classic concept of cycles of complete stand destruction and a sequence of

stand development in which old-growth stands occupy a site only a small percentage

of the time (for example, 33 percent of the time, assuming a 300-year fire rotation

and 200 years to achieve old-growth conditions). Although much of the Deer study

area approximates this classic model, much of the Cook-Quentin study area fits the

model of sustained old-growth conditions, based on the criteria of the Old-Growth

Definition Task group (1986) and Franklin and Spies (1983).

70
Human Influence on the Aboriginal ignition of forests in the western Cascade Range through intentional or

Fire Record accidental means is probable, but poorly documented. The Kalapuya Indians intentionally burned grasslands of the Willamette Valley each fall (Burke 1979). Burke also

notes that fire escape from aboriginal campfires was a probable cause of forest-fire

ignition. Aboriginal huckleberry drying on smouldering fires probably resulted in

periodic ignition of surrounding forests.3 Archeological investigations in the Middle

Fork of the Willamette River indicate that aboriginal burning may have been significant (Winkler 1984; Paul Baxter, personal communication4

) . Willamette National

Forest archaeologists5 have uncovered two aboriginal occupation sites in the CookQuentin study area and eight sites in the Deer study area, with numerous sites in

surrounding areas.

Burke (1979) postulates that forest fire incidence increased during the Euro-American

settlement period (1850-1910) because fires were started by trappers, miners, sheepherders, explorers, and others. During this period, however, the average natural fire

rotation for both study areas was 213 years compared to 127 years for the 1750-

1810 period. Fire was, thus, 1.7 times more prevalent during the aboriginal influence

period than during the Euro-American settlement period. But, during the short interval

from 1810 to 1850, when aboriginal populations were in decline from disease (Burke

1979, Dicken and Dicken 1979) and when settlers had not yet entered the area in

large numbers, the average natural fire rotation for both areas was 72 years. Lightning may be responsible for igniting most of the fires during this period of low human

influence. The short timespan of each of these three periods combined with the randomness of fire occurrence may be responsible for the observed variation between

periods. Annual precipitation recorded by dendroclimatological reconstruction

(Graumlich 1985) provides no evidence of a precipitation anomaly to explain this

variation in the natural fire rotation between 1750 and 1910.

Kilgore and Taylor (1979) report a similar decrease in fire incidence in sequoia-mixed

conifer forests of the western Sierra Nevada Mountains in the last half of the 1800’s.

Regular, intentional, aboriginal burning of the Sierran forests is documented. They

suggest that aboriginal people were a significant ignition source in parts of the

Sierras and that the dramatic decrease of aboriginal populations in the last half

of the 1800’s may be responsible for a decline in fire frequency.

Lightning is an ample cause of ignition of fires documented in this study. Burke

(1979) documents the equivalent of 0.6 lightning ignited fires per year per km2 for

1910-77, and certainly more undetected ignitions occurred. This rate of ignition is

sufficient to account for all fires documented in the study.

3

 Personal communication, Don Minore, 1988, Pacific

Northwest Research Station, Forestry Sciences Laboratory,

3200 S.W. Jefferson Way, Corvallis, OR 97331.

4

 Personal communication, Paul Baxter, 1988, Heritage Research Assoc., 1997 Garden Avenue, Eugene, OR 97403.

5

 Personal communication, Jim Cox, 1988, Pacific Northwest

Region, Mt. Baker-Snoqualmie National Forest, 1022 First

Avenue, Seattle, WA 98104.

71
Although several very small fires were caused by humans or lightning, no major fires

have occurred in the study areas since 1910 (Burke 1979). Fire suppression efforts

may have successfully reduced fire spread, but the length of record is too short to tell

if major wildfires have been eliminated from this landscape.

Conclusions and

Implications

The two areas studied in the central-western Cascade Range exhibited significant

differences and similarities in their fire regimes. Fires were less frequent, larger, and

more severe in the Deer study area than in the Cook-Quentin study area. The incidence of fire in both study areas was similar, averaging 15 years between fires

during the 1796-1893 interval and 32 years between fires during the 1515-1893

interval. Many coincident dates of fire episodes between the two study areas indicated that fires were widespread.

The natural fire rotation between 1500 and 1910 for the Cook-Quentin study area

was 95 years and 149 years for the Deer study area. The average site fire frequency

was also less for the Cook-Quentin study area (96 years) than for the Deer study

area (239 years). The natural fire rotation for the two areas as a whole was 119

years, and the average fire frequency for the sites was 168 years. Differences between fire regimes in the two study areas were, in part, because of differences in

elevation and in topographic irregularity. The fire regimes of these study areas fit the

general regional pattern where relatively infrequent, stand-replacement fires are typical in cold, wet climates and where more frequent, less severe fires are more common in warmer, drier areas. Data from the larger area of reconnaissance study,

however, suggest that the Cook-Quentin study area is more representative of the

central-western Cascade Range than the Deer study area. These values may underestimate fire frequency for two reasons. Early fires were poorly recorded because of

tree mortality in later fires. Low-severity burns were also poorly recorded, and fires

occurring at less than five sample sites were not included in the analysis. These

factors biased our estimates toward a longer natural fire rotation and lower average

fire frequency at each site.

The incidence of fire was highly variable from site to site. Some sites burned every

20 years on the average, and other sites burned once every 400 years. The fire

regime has been apparently uniform for the last 600 years, except for some 50- to

100-year periods of low fire activity.

Old-growth forests in these study areas may have originated from a sequence of fires

of variable severity. Old-growth forest conditions were sustained in parts of these

study areas for many centuries despite repeated fires.

Human influence on the fire history is difficult to determine for the study areas. The

highest fire frequency in both study areas was during a period of least human influence. Native people may have been responsible for some fire ignition. No major fires

have occurred in either study area since 1893. Similar fire-free periods occurred in

the past, possibly caused by climatic conditions or chance; the current fire-free period

could be attributed to these factors or fire suppression.

72
Interest is rising in the influence of natural and human-created patches on the forest

landscape (Franklin and Forman 1987, Harris 1984). To evaluate how patches from

harvesting affect the dynamics of forest ecosystems, scientists, land managers, and

others should consider the landscape pattern in the primeval landscape. Fires in the

Cook-Quentin and Deer study areas during the 1800’s created patches of high mortality ranging from less than 0.2 ha to about 100 ha, but 86 percent of these patches

were less than 16 ha, the average size of a clearcut on Forest Service land in the

region. Although a few large patches influenced more area, patches smaller than an

average clearcut covered a large portion of the landscape. Although elsewhere in the

Pacific Northwest, fires are known to have created some large, stand replacement

patches, it is not known whether small or large patches are predominant. To an important extent, the scale of analysis determines the patch-size distribution and the

density of stand edge that are discerned.

The patch-size distribution, the density o edge, and the dynamics of age-class

patches in natural and managed forests influence the following: output of the sediment and streamflow from watersheds; the abundance and diversity of wildlife (Black

and Thomas 1978, Thomas and others 1978, Welty 1982); effects of secondary disturbances, such as windthrow; and effects of interactions between patches in stand

development. Fire suppression and possibly decline in aboriginal ignition greatly diminished the contrast between adjacent patches from the late 1800’s until logging began in the 1950’s. Just before logging, all of the edges in these study areas occurred

between mature and old-growth stands, and contrast between patches was minor.

Before 1900, contrast between patches created by fire and the surrounding forest

was moderated by the presence of snags, logs, and remnant trees in fire-created

patches. Today, contrasts between clearcut patches and remnant forests are more

pronounced because these structural elements are scarce in clearcuts and secondgrowth stands.

Acknowledgments This report is partly from work that led to Morrison’s master’s professional paper in

1984 at the University of Washington. James Agee (National Park Service - University

of Washington Cooperative Studies Unit) provided invaluable advice during the analysis phase of the project. This help, as well as his review of the draft manuscript, is

greatly appreciated. A. McKee, J. Franklin, M. Hemstrom, T. Spies, and J. Means

provided helpful suggestions and stimulating discussion during several phases of the

study; P. Teensma assisted in data collection at several sites and reviewed the draft

manuscript. Funding for this study was provided by the National Science Foundation

(Grant No. BRS-8508356 and BRS-8514325) and the USDA Forest Service, Pacific

Northwest Research Station (Cooperative Agreement No. 84-355).

I English Equivalents 1 square kilometer (km2

) = 0.39 square mile

1 hectare (ha) = 2.47 acres

1 millimeter (mm) = 0.039 inch

1 centimeter (cm) = 0.39 inch

1 meter (m) = 1.09 yards

73
References Arno, S.F. 1976. The historical role of fire on the Bitterroot National Forest. Res.

Pap. INT-187. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 29 p.

Arno, S.F. 1982. Classifying forest succession on four habitat types in western

Montana. In: Means, Joseph E., ed. Forest succession and stand development

research in the Northwest: Proceedings of a symposium; 1981 March 26;

Corvallis, OR. Corvallis, OR: Forest Research Laboratory. Oregon State

University: 54-62.

Arno, S.F.; Sneck, K.M. 1977. A method for determining fire history in coniferous

forests of the mountain West. Gen. Tech Rep. INT-42. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment

Station. 28 p.

Atzet, Thomas; Wheeler, David; Gripp, Russell. 1986. Fire and forestry in

southwest Oregon. Fir Report. Corvallis, OR: Oregon State University. 9(4): 4-7.

Black, H., Jr.; Thomas, J.W. 1978. Forest and range wildlife habitat management:

ecological principles and management systems. In: Proceedings of the workshop

on nongame bird habitat management in the coniferous forests of the Western

United States. Gen. Tech. Rep. PNW-64. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment

Station: 47-55.

Boone, RD.; Cromack, K., Jr.; Sollins, P. 1982. Changes in soil carbon levels

through a forest mortality wave induced by Phellinus weiri. Bulletin of the Ecological Society of America. 63(2): 181. Abstract.

Burke, Constance J. 1979. Historic fires in the central western Cascades, Oregon.

Corvallis, OR: Oregon State University. 130 p. M.S. thesis.

Childs, T.W.; Shea, K.R. 1967. Annual losses from diseases in Pacific Northwest

forests. Resour. Bull. PNWQO. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Forest and Range Experiment Station. 19 p.

Cook, S.A. 1982. Stand development in the presence of a pathogen, Phellinus weirii.

In: Means, Joseph E., ed. Forest successsion and stand development research in

the Northwest: Proceedings of a symposium; 1981 March 26; Corvallis, OR.

Corvallis, OR: Forest Research Laboratory. Oregon State University: 159-163.

Craighead, F.C. 1927. Abnormalities in annual rings resulting from fires. Journal of

Forestry. 25(7): 840-842.

Dicken, S.N.; Dicken, E.F. 1979. The making of Oregon. Portland, OR: Oregon

Historical Society. 208 p.

Dieterich, J.H. 1980. Chimney Spring forest fire history. Res. Pap. RM-220. Fort

Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station. 8 p.

I 74
Dyrness, C.T.; Franklin, Jerry F.; Moir, W.H. 1974. A preliminary classification of

forest communities in the central portion of the western Cascades in Oregon.

Conif. For. Biome Bull. 7. Seattle: University of Washington. 248 p.

Franklin, J.F.; Cromack, K., Jr.; Denison, W. [and others]. 1981. Ecological

characteristics of old-growth Douglas-fir forests. Gen. Tech. Rep. PNW-118.

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

Forest and Range Experiment Station. 48 p.

Franklin, Jerry F.; Dyrness, C.T. 1973. Natural vegetation of Oregon and

Washington. Gen. Tech. Rep. PNW8. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment

Station. 417 p.

Franklin, Jerry F.; Forman, Richard T.T. 1987. Creating landscape patterns by

cutting: ecological consequences and principles. Landscape Ecology. 1(1): 5-18.

Franklin, Jerry F.; Spies, T.A. 1984. Characteristics of old-growth Douglas-fir

forests. In: Proceedings, SAF national convention; 1983 October 16-20; Portland,

OR. Washington, DC: Society of American Foresters: 328-334.

Gratkowski, H.J. 1956. Windthrow around staggered settings in old-growth Douglasfir. Forest Science. 2: 60-74.

Graumllch, Lisa. 1965. Long-term records of temperature and precipitation in the

Pacific Northwest derived from tree rings. Seattle, WA: University of Washington.

198 p. Ph.D. Dissertation.

Harris, Larry D. 1984. The fragmented forest. Chicago, IL: The University of Chicago

Press. 211 p.

Heinselman, M.L. 1973. Fire in the virgin forests of the Boundary Waters Canoe

Area, Minnesota. Quaternary Research. 3(3): 329-382.

Hemstrom, Miles A.: Franklin, J.F. 1982. Fire and other disturbances of the forests

in Mount Rainier National Park. Quaternary Research. 18: 32-51.

Hickman, James C. 1976. Non-forest vegetation of the central western Cascade

Mountains of Oregon. Northwest Science. 50(3): 145-155.

Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific Northwest: an

illustrated manual. Seattle, WA: University of Washington Press. 730 p.

Juday, Glenn Patrlck. 1977. The location, composition, and structure of old-growth

forests of the Oregon Coast Range. Corvallis, OR: Oregon State University. 140 p.

Ph.D. dissertation,

Keen, F.P. 1937. Climatic cycles in eastern Oregon as indicated by tree rings.

Monthly Weather Review. 65(5): 175-188.

75
Kilgore, B.M.; Taylor, D. 1979. Fire history of a sequoia-mixed conifer forest.

Ecology. 60(1): 129-142.

Lynott, R.E.; Cramer, O.P. 1966. Detailed analysis of the 1962 Columbus Day

windstorm in Oregon and Washington. Monthly Weather Review. 94: 105-117.

Martin, R.E.; Robinson, D.D.; and Schaeffer, W.H. 1976. Fire in the Pacific

Northwest--perspectives and problems. In: Proceedings, 15th annual Tall Timbers Fire Ecology Conference, Tallahassee, FL: Tall Timbers Research Station.

15: 1-23.

Means, Joseph E. 1981. Development history of dry coniferous forests in the central

western Cascade Range of Oregon. In: Proceedings of Forest succession and

stand development research; 1981 March 26; Corvallis, OR. Corvallis: Forest

Research Laboratory, Oregon State University: 142-158.

Morris, William G. 1934. Forest fires in western Oregon and western Washington.

Oregon Historical Quarterly. 35: 313-339.

Morrison, Peter H. 1975. Ecological and geomorphological consequences of mass

movements in the Alder Creek watershed and implications for forest land management. Eugene, OR: University of Oregon 102 p. B.A. thesis.

Old-Growth Definition Task Group. 1966. Interim definitions for old-growth Douglasfir and mixed-conifer forests in the Pacific Northwest and California. Res. Note

PNW-447. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 7 p.

Orr, P.W. 1963. Windthrown timber survey in the Pacific Northwest, 1962. Portland,

OR: U.S. Department of Agriculture, Forest Service, Insect and Disease Control

Branch, Division of Timber Management, Pacific Northwest Region. 22 p.

Plummer, F.G. 1903. Central portion of the Cascade Range Forest Reserve. In:

Forest conditions in the Cascade Range Forest Reserve. Prof. Pap. 9, Ser. H.

Forestry 6. Washington, DC: U.S. Department of the Interior, Geological Survey:

71-146.

Romme, William. 1980. Fire history terminology: Report of the ad hoc committee In:

Stokes, M.A., Dieterich, J. H., tech. coords. Proceedings of the Fire History Workshop. Oct. 20-24, 1980. Tucson, AZ. Gen. Tech. Rep. RM-81. Fort Collins, CO:

U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range

Experiment Station 142 p.

Rudlnsky, J.A., ed. 1979. Forest insect survey and control: a syllabus. Corvallis, OR:

Oregon State University Book Store Inc. Oregon State University. 391 p.

Stewart, Glenn H. 1984. Forest structure and regeneration in the Tsuga heterophyllaAbies amabilis transition zone, central western Cascades, Oregon. Corvallis, OR:

Oregon State University. 150 p. Ph.D. dissertation.

76
Stewart, Glenn H. 1986. Population dynamics of a montane conifer forest western

Cascade Range, Oregon, USA. Ecology. 67: 534-544.

Tande, G.F. 1979. Fire history and vegetation pattern of coniferous forests in Jasper

National Park, Alberta. Canadian Journal of Botany 57: 1912-1931.

Thomas, J.W.; Maser, C.; Rodlek, J.E. 1978. Edges-their interspersion, resulting

diversity and its measurement. In: Proceedings of the workshop on nongame bird

habitat management in the coniferous forests of the Western United States: Feb.

7-9, 1977, Gen. Tech. Rep. PNW-64. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station:

91-100.

Waring, R.H.; Holbo, H.R.; Bueb, R.P.; Fredriksen, R.L. 1978. Documentation of

meteorological data from the Coniferous Forest Biome primary station in Oregon.

Gen. Tech. Rep. PNW-73. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station. 23 p.

Welty, J.C. 1978. The life of birds. New York: CBS College Publishing. 754 p.

Wickman, Boyd E.; Mason, Richard R.; Thompson, C.G. 1973. Major outbreaks of

the Douglas-fir tussock moth in Oregon and California. Gen. Tech. Rep. PNW-5.

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

Forest and Range Experiment Station, 18 p.

Winkler, Carol J. 1984. A site location analysis for the Middle Fork of the Willamette

River watershed. Eugene, OR: University of Oregon. 63 p. M.S. thesis.

Yamaguchi, David K. 1986. The development of old-growth Douglas-fir forests

northeast of Mount St. Helens, Washington, following an 1480 eruption. Seattle:

University of Washington. 100 p. Ph.D. dissertation.

Zackrisson, Olle. 1986. Forest fire history: ecological significance and dating

problems in the north Swedish boreal forest. In: Stokes, M.A.; Dieterich, J.H., tech.

coords. Proceedings of the Fire History Workshop; 1980 October 20-24; Tucson,

AZ. Gen. Tech. Rep. RM-81. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range Experiment Station: 120-125.

Zar, Jerrold H. 1974. Biostatistical analysis. Englewood Cliffs, NJ: Prentice-Hall.

620 p.

Zobel, Donald B.; McKee, Arthur; Hawk, Glenn M.; Dyrness, C.T. 1976.

Relationship of environment to composition, structure, and diversity of forest

communities of the central western Cascades of Oregon. Ecological Monographs.

46(2): 135-156.

77
This page left blank intentionally
, ._.

-2

Morrison, Peter H.; Swanson, Frederick J. 1990. Fire history and pattern in a

Cascade Range landscape. Gen. Tech. Rep. PNW-GTR-2-54. Portland, OR:

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

Station. 77 p. -

Fire history from years 1150 to 1985 was reconstructed by analyzing forest stands in

two 1940-hectare areas in the central-western Cascade Range of Oregon. Serving as

records for major fires episodes, these stands revealed a highly variable fire regime.

The steeper, more dissected, lower elevation Cook-Quentin study area experienced

more frequent fires (natural fire rotation = 95 years) that were commonly low to moderate in severity. The Deer study area, with its cooler, moister conditions and gentler

topography, had a regime of less frequent (natural fire rotation = 149 years), predominantly stand-replacement fires. Fires created a complex mosaic of stands with variable date and severity of last burn. Fire-created forest patches originating in 1800-

1900 are mostly less than 10 hectares. Since 1900, very little of the study areas

burned, possibly because of fire suppression. Old-growth forest conditions have

persisted on some sites through numerous fires and over many centuries.

Keywords: History (fire), patch dynamics, old-growth forest, wildfire fire ecology.

The Forest Service of the U.S. Department of

Agriculture is dedicated to the principle of multiple

use management of the Nation’s forest resources

for sustained yields of wood, water, forage, wildlife,

and recreation. Through forestry research,

cooperation with the States and private forest

owners, and management of the National Forests

and National Grasslands, it strives-as directed by

Congress-to provide increasingly greater service

to a growing Nation.

The U.S. Department of Agriculture is an Equal

Opportunity Employer. Applicants for all Department

programs will be given equal consideration without

regard to age, race, color, sex, religion, or national

origin.

Pacific Northwest Research Station

319 S.W. Pine St.

P.O. Box 3890

Portland, Oregon 97208-3890
U.S. Department of Agriculture BULK RATE

Pacific Northwest Research Station POSTAGE 

+

FEES PAID

319 SW. Pine Street USDA-FS

P.O. Box 3890 PERMIT No. G-40

Portland, 0regon 97208

Official Business

Penalty for Private Use, $300