Fire Management in Southern California1
Michael J. Rogers2
Wildland wildfires have had a major environmental influence in Southern California for two
million years or more (Axelrod 1958). Analysis
of charcoal layers in lake and ocean bottoms has
provided evidence of periodic wildfires (Bryne
and others 1977). Examination of fire scars on
older conifers also provides additional data on
high intensity fire frequency prior to the
establishment of official, written records (Arno
and Sneck 1977).
The early day missionaries, who began the
first non native American settlements, started a
migration to Southern California that continues
even today. Father Junipero Serra and his Franciscan followers founded numerous missions which
became the cornerstone of community development
in Southern California. Large Spanish Land Grant
ranches soon surrounded each mission. These
early day settlers may have used fires as a means
of clearing the vegetation from the fertile valley floors and alluvial plains (Komarek 1969)
that stretched from the mountain slopes to the
shores of the Pacific Ocean. The deep alluvial
soils in the valleys below the coastal mountains
produced good feed for cattle, good wells, numerous crops, vineyards, avocado and citrus groves.
As the population grew, additional ranches and
farms sprang up on the more marginal terrain.
Eventually ranches and farms occupied all the
valley lands from the shores of the Pacific Ocean
to the rugged slopes of the Coast Range. Occasionally droughts created hard times for the
ranchers. Wildfires in the valleys and the foothills often accompanied these droughts.
Dana, in his book "Twenty Years Before The
Mast", states that in 1836 he encountered a great
forest fire all along the Southern California
Coast Range during his journey northward to Santa
1Presented at the Symposium on Dynamics and
Management of Mediterranean-type Ecosystems,
June 22-26, 1981, San Diego, California.
Abstract: Fire has always played a major role in
Southern California. Fire suppression forces
have a good record controlling brush fires under
normal weather conditions. Present suppression
strategies become ineffective on wind driven
fires under "Santa Ana" weather conditions.
Prescribed burning has emerged as a viable tool
for developing age class mosaics. Age class
mosaics should become the key building block of
a totally integrated fire management program.
This kind of program will significantly reduce
suppression costs, wildfire damage, related
flood damage and sediment reduction while providing optimum benefits to wildlife, water, timber,
range and recreation.
Barbara. Periodically, newspapers carried accounts of raging forest fires in the coast range
mountains of Southern California. Specific newspaper accounts of Southern California wildfire
activity occurred in 1869, 1872 and 1878. During
these early years residents expressed little
direct concern over these wildfires.
Cattlemen intentionally set many fires in the
valleys and foothill areas as late as the 1870's
and 1880's. Finally, in 1884, a series of severe
winter storms hit Southern California. The new
Southern Pacific Railroad suffered heavy damage
as a result of the flooding. Following this
episode, intentional burning of vegetation ceased.
Periodically, however, large wildfires would break
out, usually in the fall. These wildfires eventually reached the mountains where they burned
themselves out after running into old burns
(Barret 1935).
In 1896, Southern California experienced a
severe drought accompanied by high summer temperatures and strong winds. The numerous wildfires
that occurred and the flood damage that followed
resulted in a loud outcry of local protest. As a
result, the Federal Government initiated plans to
establish fire fighting organizations for all of
the newly created forest reserves in Arizona, New
Mexico and California.
In spite of these efforts, wildfires continued
to occur. To combat the threat of large wildfires
the Forest Service attempted to contain each fire
at the smallest size possible. In the early
1930's the Forest Service protection policy called
for immediate attack and suppression of absolutely
all fires that occurred.3 Under this policy mature chaparral would eventually form a thick
continuous cover over the soil. Sooner or later
a wildfire would break out under extreme weather
conditions and all of the steep mountain watersheds would burn. Serious flood and debris
problems usually followed on the heels of these
wildfires. After repairing the storm damage
2Fire Management Officer, Angeles National
Forest, Forest Service, U.S. Department of
Agriculture, Pasadena, California 91101.
3Personal communication from Chief F.A. Silcox
to Regional Foresters, Forest Service, U.S. Department of Agriculture, 1935.
496
Gen. Tech. Rep. PSW-58. Berkeley, CA: Pacific Southwest Forest and Range
Experiment Station, Forest Service, U.S. Department of Agriculture; 1982.
Forest Service personnel would then start all over
again, protecting the new brush until it became
old and decadent and would again burn under high
intensity wildfire conditions. This unsuccessful
policy of complete fire exclusion continued until
1978.
In addition to implementing a policy of complete wildfire prevention and suppression, the Forest
Service took several positive steps in an effort
to disarm the explosive potential of the steep
brush covered mountain slopes. As fire fighters
began to use mechanized equipment to control wildfires, the Southern California Forest Managers
began implementing a system of preattack planning.
This planning system inventoried all those ridges
where mechanized equipment could be worked effectively. The fire fighter now had a way to preplan
the placement of bulldozers and other equipment
before a wildfire occurred. Unfortunately, wild
fires would usually overrun these ridges before
the equipment could construct the firebreaks.
After repeated failures the Forest Service began
requesting and receiving additional funds to preconstruct many of these improvements, especially
firebreaks. Wildfires burning under extreme adverse weather conditions quickly overran the
preconstructed firebreaks. Heavy winter rains and
intense summer thunder showers also caused unacceptable erosion on these firebreaks.
Eventually, firebreaks gave way to the wider
fuelbreaks. Fuelbreaks support low growing and
low volume vegetation which helps to reduce erosion while providing a safe place for fire fighters
to make a stand. We learned that even with wide
fuelbreak systems supported by roads, heliports
and strategically located water systems, under
extreme adverse weather conditions (low humidities,
low live fuel moistures and strong winds) fire
fighters could not effectively isolate a wildfire
within the established fuelbreak system. (Pinecrest, Sage, Monte, Crown Valley, Placerita Fires
1979; Mountain Trail 1978; Middle Fire 1977; Mill,
Village Fires 1975). However, the fuelbreak system
did become highly useful for containing wildfires
once the adverse wind conditions subsided.
Fuelbreaks will continue to play a key role in
reducing the number of acres burned under most
high intensity wildfire conditions except under
strong Santa Ana wind conditions. However, even
under the less extreme weather conditions, fuelbreaks alone will not eliminate the soil damage
resulting from the high intensity wildfires that
burn between the fuelbreak system (Mountain Trail
Fire 1978; Pine Crest Fire 1979; and Stable Fire
1980).
Suppression expenditures and related resource
damages represent just the tip of the iceberg in
terms of wildfire-flood related costs and losses.
As an example, the 1975 Mill Fire cost $1.5 MM to
suppress and it resulted in some $200,000 in
resource damages. The floods and debris which followed this high intensity wildfire in February
1978 caused an additional estimated $75MM in
property losses and damages. The majority of the
flood and debris damage that occurred throughout
Los Angeles County in 1978 could be traced back to
recent high intensity wildfires.
In spite of all our best prevention, detection,
suppression, preattack, firebreak and fuelbreak
strategies and the money spent to implement these
strategies, we still seem unable to reduce the
number of high intensity wildfires that burn under
extreme weather conditions and the damages associated with these wildfires. The number of wildfire
starts continues to grow each year with 60 wildfires in 1970 to 131 wildfires in 1979.4 For
the past thirty years wildfires have burned an
average of 18,500 acres on the Angeles National
Forest: 1950-1959 16,917 acres; 1960-1969 21,395
acres; 1970-1979 18,511 acres. Most of these
large acreage losses have occurred between September and December under high velocity Northeast
Santa Ana winds. These wind driven wildfires
continue to be the single greatest cause of soil
damage and personal property loss in Southern
California. Some typical examples of personal
property loss follow in Table 1. Unfortunately
statistics are not available for the number of
structures actually saved under conflagration
conditions.
Table 1--Dwellings Lost in Conflagration Wildfires, 1970-1980.
Fire
Name
Boulder
Mill
Sycamore
Date
9/70
11/75
7/77
Mandeville
Canyon
Kanan
10/78
Stable
11/80
Thunder
11/80
Panorama
11/80
10/78
Jurisdiction
At Point Of
Origin
Cleveland
National Forest
Angeles
National Forest
Los Padres
National Forest
Los Angeles
City
Los Angeles
County
Los Angeles
County
Angeles
National Forest
San Bernardino
National Forest
Homes
Destroyed
383
15
216
20
230
57
26
284
Each wildfire precludes managements option for
controlling the timing of quality water yields,
creating optimum wildlife habitat conditions, reducing losses of forest soils, providing additional
area for grazing, establishing tree plantations
and healthy chaparral stands for future dispersed
recreation opportunities and for allowing greater
use of those portions of forests now restricted by
annual fire closures.
4Data on file, USDA Forest Service, Angeles
National Forest, Pasadena, California
497
The long, warm, dry summers and mild winters
that originally made the Spanish feel at home still
continue to draw 200,000 Americans to Southern
California each year. Single family residences,
apartments and condominiums have long since replaced the ranches, orchards and vineyards
established by early day settlers. The unending
demand for additional housing and privacy has become so intense that residential developments now
compete for the only remaining land base, the
steep brush covered privately owned hillsides.
Residents of these areas have little understanding
or appreciation for the hazards involved with
living in the urban wildland interface. Fire
Management problems continue to become increasingly
complex.
Can anything be done to charge or correct what
appears to be a growing and totally hopeless situation? Yes, a number of things can be done,
however, there are no simple or individual
solutions to this complex problem. From the
stand point of vegetation management, the fuels
that lie between the fuelbreaks must be conscientiously managed and not just protected. Prior to
1975 none of our management strategies suggested
managing the carpet of chaparral fuels that lay
between the fuelbreaks. Fire modeling (Albini
1976) and personal observations suggest that by
managing the age of the fuels the manager can
favorably influence fire intensity. The older
the fuel, the greater the dead to live fuel ratio
and the greater the resulting intensity once
ignition occurs (Green 1980).
The data in Table 2 illustrates this point
very graphically5.
Table 2--Brush Fuel Model with Slope at 50 percent,
10 Hour Fuel Stick of 2.0, Wind Speed of 20 Miles
Per Hour, on September 4.
Age
(Years)
10
20
30
40
50
Flame Length
(In Feet)
6.36
5.89
19.26
30.09
33.65
Intensity
BTU/Sec/Ft
316
267
3,518
9,284
11,838
Size(Acres
in 1st Hour)
142
7
102
280
384
With wind, slope and fuel moisture held constant
and age of the vegetation the only variable, one
can readily see that fire intensity, resistance to
control, and acres burned in the first hour begins
to increase rapidly beyond twenty years of age.
The rapid increase in the dead to live fuel ratio
beyond twenty years of age causes these increases.
Most of the chaparral species have produced viable
seed by their fifteenth year. This data suggests
then that somewhere between 15 and 20 years of age,
chamise-chaparral vegetation should be converted
back to the age of zero, or burned under a
5Van Gelder, Randall, J. Unpublished Firecasting
Operators Guide on file at the Fire Lab, Riverside,
California.
498
prescription that will remove a large percentage of
the smaller sized dead fuels. Prescribed burning
can be carried out under a carefully coordinated
plan which will result in a mosaic of different age
classes.
Age class management enables the land manager
to have a good deal of control over wildfire intensity and related resource and off site damages.
Wildfire suppression should be more effective in
the younger, thriftier chaparral fuels. In addition the land manager can now begin to realistically
plan for other resource opportunities such as
increased grazing, an increase in wildlife habitat
diversity, and an increase in quality water yields.
Because of the steep slopes and fragile soils,
it appears that very few alternative methods of
large scale vegetative management other than prescribed burning could be successfully implemented
in the Angeles National Forest. The Southern
California National Forests have used prescribed
burning with a high degree of success as a vegetative management tool since 1977.
Based on our experience on the Angeles with both
wildfires and prescribed fire I offer the following
observations and opinions:
FIRE INTENSITY EFFECTS
The flood damage that follows wildfires can be
directly related to two factors: (1) wildfire
intensity and (2) storm intensity. Wildfire
intensity increases with the age of the fuels.
The combination of older fuels burning under a
September-December hot dry Northeast wind conditions creates some of the highest wildfire
intensities possible. Not only does an intense
fir burning in late summer after a long drying
period consume all of the organic matter in the
soil, it can destroy the soil structure and create
a "water repellent" soil condition. The more
intense the fire the greater the change that this
"water repellent" soil condition will develop.
However, if abundant rain falls, surface water will
start flowing down the steep slopes and as these
flows gain velocity soil particles become detached
and transported. Surface rilling and slumping
starts to occur. Major channels scour out down
to solid parent material. Tons of debris begin
to flow off the slopes and out of the forests into
residential areas that border the foothills. All
of the main channels in the fire area will carry
major debris flows which on the Angeles will
usually be contained in debris basins. These
debris basins must be cleaned out periodically, at
a present day cost of $8.00/cubic yard. During
periods of heavy rainfall clean out activities
must occur on a daily basis just to keep up with
the new debris flowing into the structures. If
the daily clean out did not occur hundreds of
homes below these structures would be destroyed
by flowing debris.
Very extensive "water repellent" soil conditions
occurred during the 1975 Angeles National Forest
Mill Fire, in 56-year-old-fuels. Fortunately
only light winter storms occurred during the next
two winters. Extensive "water repellent" soils
also occurred on the 1977 Middle Fire which burned
in 75-year-old-fuels. Heavy winter storms in 1978
produced major debris flows from these two burns
which resulted in extensive flood damage and loss
of life6.
This pattern of severe flooding did not occur
however on another wildfire known as the Mountain
Trail Fire. The Mountain Trail Fire started on
October 23, 1978 under strong Santa Ana wind conditions and burned all of the watershed north of
the City of Sierra Madre. In 1978/1979 Southern
California experienced another wet winter with
expectations for heavy flood damage in the City
of Sierra Madre. However, the city did not experience any heavy flooding or debris damage. A
review of the fire history records indicated that
the Mountain Trail Fire area had not burned since
the 1961 Sierra Fire which also occurred under
strong Santa Ana wind conditions. During the
winter following the Sierra Fire the town of
Sierra Madre suffered heavy flooding resulting in
extensive damage to numerous homes. Deep rilling,
gullying, and slumping had occurred on the mountain slopes sending tons of debris into the city
below. Prior to the Sierra Fire, this area had
not completely burned since 1911. The Sierra Fire,
therefore, burned in 50-year-old-fuel. By
contrast, the Mountain Trail Fire burned in 17-yearold-fuel, a relatively thrifty fuel. Although all
of the stream channels on the-Mountain Trail Fire
produced record amounts of debris, most of this
material had accumulated in the ravine and canyon
bottoms as dry creep long before the 1978 Mountain
Trail Fire. The burning of the thriftier fuels,
even under extreme weather conditions, did not
result in the extensive "water repellent" soil
condition that has developed on other high intensity fall wildfires.
During the winters of 1977/78 and 78/79 Ranger
District personnel conducted numerous prescribed
burns throughout the Angeles National Forest.
Many of these burns took place prior to heavy
torrential winter rains, the same rains that caused
extensive flood damage on areas burned over in the
Mill and Middle Fires. We did not observe any
rilling or extensive soil movement on these prescribed burn areas. The low intensity prescribed
fires, some of them in 60-year-old-fuels, did not
create the "water repellent" soil condition that
develops when high intensity wildfires burn under
extreme weather conditions in older fuel beds. In
fact, within two weeks 90 percent of the prescribed
burn areas had a cover of grass or herbaceous plants.
In addition to carefully prescribed fuel and
weather conditions at the time these burns took
place, the soils at all burn sites had high
moisture contents due to the long and above normal
winter-spring rainy season. By contrast, our
6Los Angeles Times feature on a study conducted
by California Institute of Technology, Pasadena,
California on the Relationship of Wildfire Intensity
to Soil Damage; March 5, 1978.
damaging wildfires occur in the fall, in older
fuel beds, after all the forest fuels have dried
out and the living vegetation has become dormant.
In April 1980, during a period of 80 mph Northeast winds, some hot material rekindled and escaped
outside the burned area perimeter. The resulting
wildfire burned in 60-year-old-fuels. Before the
winds finally died down the Monroe Fire had consumed 3,000 acres. However, this wildfire occurred
in the spring during a time of very high soil
moisture. As with all of our prescribed burns new
vegetation started to appear within two weeks. By
June the burn contained a new carpet of vegetation.
Research personnel examined the soils and concurred
that little if any "water repellent" soil conditions had developed.
The Mountain Trail Fire and the Monroe Fire
demonstrate two important concepts.
1.
We can influence wildfire intensity by
conscientiously managing chaparral fuels in a
mosaic of various age classes. The 1978 Mountain
Trail Fire showed that less soil damage occurs
when younger, thriftier fuels burn then when older fuels burn, even under extreme wildfire
conditions.
2.
The 1980 Monroe Fire suggests that intense
winter/spring fires in the old fuels do not
seriously destroy soil structure as do high intensity wildfires in the fall. The high soil moisture
content present during Spring Fires appears to
play a key role in preventing the creation of
"water repellent" soils. We have all observed
that vegetative recovery on fall burns occurs very
slowly, while on spring burns the reverse
situation occurs.
PRESCRIBED BURNING AS A MANAGEMENT TOOL
Prescribed burning has several distinct advantages over wildfire in that it offers the manager
the opportunity to control the size and shape of
the burn. Under wildfire conditions no such
control exists. If the manager observes the
prescribed burn producing higher soil temperatures
then desired, the firing pattern can be adjusted
accordingly. Again under wildfire conditions no
such opportunity exists.
With prescribed burning the manager can select
the timing and the conditions required to produce
an end product consistent with pre established
objectives. Again, under wildfire conditions
this opportunity does not exist.
As we continue to gain experience with prescribed burning, we must develop the capability
of burning several thousand acres each day. This
concept seemed impossible to even think about
several years ago. However, the helitorch now
provides us with the capability needed to burn
large areas each day. With all of the various
constraints we work under such as (1) no burn
days because of poor air quality, (2) no burn
day because the burn falls out of the prescription
499
on either the low end (humidity and fuel stick too
high, no wind, fire won't burn) or the high end
(humidity and fuel stick too low, wind too strong,
any fire could be too intense), (3) no burn days
because a very complex high risk burn will be ignited on an adjoining district and back up forces
from neighboring units must be reserved in the
case of an escape, (4) insufficient humidity
recovery at night which constrains the manager
from initiating new prescribed burns until "mop
up" of previous burns can be accomplished. This
all means that once each critical factor falls
into prescription, good soil moisture exists,
good humidity recovery occurs in late afternoon
and stays through the night, air quality conditions
permit prescribed fires and the weather forecast
looks favorable for continuation of similar
conditions for the next 48 hours or more the
manager must move rapidly to accomplish as many
acres as possible. For example the goal of
18,000-19,000 acres each year on the Angeles may
conceivably take place on 8 to 10 key days where
all factors favor planned ignition. These 8 to
10 burn days may be scattered throughout the
winter, spring and early summer, between November
and early July. Fortunately, the risks will
lessen as we eliminate more and more of our 30year-old and older fuels.
Hopefully costs can be cut by accomplishing
more and more burning without using expensive
preconstructed fire lines. We have successfully
used humidity recovery on several burns including
the Horse Ridge Fuel break in April 1978, and the
Drinkwater Fuel Reduction Project in May 1978. In
both these cases the humidities rose to the point
at about 3:00 pm where we could no longer ignite
the fuels. Sustained high humidities through the
night nearly extinguished all fire on both projects.
Prescribed burn managers monitered the relative
humidities using on site hygrothermographs.
PREVENTING PRESCRIBED FIRE ESCAPES
As previously mentioned the Winter-Spring of
1980 proved to be a totally different kind of
year. Humidity recovery above 60 percent rarely
occurred for sustained periods. Northeast winds
periodically surfaced throughout the winter-spring
burning period. On April 11, 1980 a Northeast
wind with unpredicted velocities of 80 mph surfaced over the Angeles National Forest. Two
prescribed burns initiated originally on April 7
eventually escaped. Both wildfires headed towards
heavily populated areas. The Dagger Burn consumed
705 acres and the Monroe Burn consumed approximately
3,000 acres. Fortunately the winds died down before either of these two fires reached the wildland urban interface.
Some cautions and considerations for use of
prescribed fire in a Mediterranean-type Ecosystem:
1. Under strong wind conditions, the vegetation
in a Mediterranean-type Ecosystem will burn at any
time of the year. The probability for an intense
fast running fire increases dramatically as the
500
fuels exceed 20 years of age. Our most dangerous
winds, the strong Northeast winds, can occur during
any month of the year. The data in Table 3 comes
from a 10 year study (1951-1960) of Santa Ana
wind frequency on the Angeles National Forest
(Schroeder and others 1964).
Table 3--Santa Ana Wind Frequency by Month for the
Angeles National Forest.
Month
January
February
March
April
May
June
July
August
September
October
November
December
Avg. No.
Santa Ana
Events Each
Year
0.7
1.0
1.7
0.8
0.7
0.4
0.2
0.0
1.1
1.9
2.6
1.8
Average
Duration
(In days)
1.7
1.9
2.5
1.8
1.4
4.5
2.5
0.0
4.4
4.5
5.0
3.7
Avg. No.
Santa Ana
Days Per
Month
1.2
1.9
4.3
1.5
1.0
1.8
.5
0.0
4.8
8.6
12.8
6.6
The probability of high velocity Northeast winds
must always be considered when planning to burn.
The combination of strong Northeast winds, wildfire
and the floods that follow destroy more structures
in the wildland urban interface than any other
combination of causes.
2. Managers must resist pressures to take risks
that they find unacceptable. We have began to
build a good solid fuel management program. Admittedly, we have made some mistakes and we have
grown from these mistakes. We received criticism
that our rate of progress is not fast enough.
Today we stand at the crossroads: we can develop
a good solid prescribed burning program and continue to enhance our creditability as professional
land managers or we can wind up losing this opportunity by becoming overly ambitious and taking
some foolish chances.
3. In Southern California, it would be unusual
to find good prescription conditions must past
July. Therefore, it will remain necessary to
attack all those wildfires occurring during the
summer and fall with a rapid and aggressive suppression effort. Some people advocate letting
wildfires go during the summer wildfire season.
They claim these wildfires would develop a natural
age class mosaic. Perhaps this concept might have
worked prior to the intrusion of residential
development into the privately owned wildlands of
California. Today, however, to let a wildfire run
loose to the point it could endanger or destroy
private property if winds developed would be
totally irresponsible. If we allowed this to
happen the public would be justified in asking if
there is a difference between prescribed fire
and wildfire. A prescribed fire must always be
fully under control and designed in such a way
that it meets a predetermined objective using a
predetermined set of constraints. A wildfire
knows no such bounds. No opportunity exists to
control the size, shape, intensity or timing of
a wildfire. In addition, based on our experience
the soil damage from a summer wildfire would not be
acceptable.
4. There will never be one single answer to
all of our wildland management problems. Although
age class management will reduce fire intensity,
under strong wind conditions, any fuel age class
will burn. Additionally, in strong winds, airtankers and helitankers that usually can be more
effective in lighter fuels often can not get off
the ground because of the extreme air turbulence.
During the Stable and Thunder Fires, 5, 10 and 30
year-old-fuels all burned with equal rates of
spread. Aircraft could not be used until the
Northeast winds finally subsided. We can, however,
expect less soil damage under the younger age class
fuels because of the lower intensities, which means
less flood damage under these conditions. Homes
in the path of a wildfire in any fuel type will be
destroyed unless communities insist on fire safe
building practices, such as fire safe roofs, closed
eaves, properly placed attic vents, small windows,
and proper landscaping in wildfire prone areas.
SUMMARY
Any successful wildland protection program
must be built on an integrated approach consisting
of:
1. A plan and financing for a vegetative
management program that will reduce the intensity
and the number of large wildfires while producing
timber, recreation, range, wildlife, water and
other benefits.
2. A continuation of a strong wildfire prevention effort. This prevention effort should
also emphasize public education so that hazards of
wildfire in a Mediterranean ecosystem are well
understood.
3. A strong ground and air initial attack
suppression organization with cooperator back up
in the event a project wildfire occurs.
4. Homeowners living in Southern California's
brushlands must have the benefit of living in fire
safe homes built in areas that can be effectively
defended from wildfire by both the homeowner and
the fire services. Greenbelt or buffer concepts,
fire safe building codes and low growing fire
resistant vegetation should be fully integrated
to provide this protection. New structures should
be effectively separated from brush stands.
I believe that we can reduce fire and flood
related losses considerably while enhancing other
resource values by implementing a totally integrated protection strategy like the one I have
described.
LITERATURE CITED
Axelrod, D.I. Evolution of Madro-Teritiary geoflora. Bot. Rev 24:433-509, 1958.
Albini, Frank A. Estimating Wildfire Behavior and
Effects. Ogden, Utah.: Intermountain Forest
and Range Exp. Stn., Forest Serv., U.S. Dep.
Agric.: 1976: Gen. Tech. Rep. INT-42. 92 p.
illus.
Arno, Stephen F.; Sneck, Kathy M. A method for
determining fire history in coniferous forests
of the mountain west. Ogden, Utah: Intermountain Forest and Range Exp. Stn., Forest Serv.,
U.S. Dep. Agric.: 1977; Gen. Tech. Rep.INT-42.
28 p.
Barret. L.A. A record of forest and field fires
from the days of the early explorers to the
creation of the Forest Reserves. File at the
Pacific Southwest Forest and Range Exp. Stn.
Library.; Forest Serv.; U.S. Dep. of Agric.;
1935, 171 p.
Byrne, Roger; Michaelson, Joel; Soutar, Andrew.
Fossil charcoal as a measure of wildfire frequency
in Southern California. A preliminary analysis.
Proceedings of the Symposium of Environmental
Consequences of Fire and Fuel Management in
Mediterranean Ecosystems; 1977 August 1-5; Palo
Alto, Calif.; 361-366.
Green, Lisle R. Burning by Prescription in
Chaparral in California; A Summary of What We
Know. Berkeley, California; Pacific Southwest
Forest and Range Exp. Stn.; Forest Serv., U.S.
Dep. Agric.; 1980 Gen. Tech. Rep. PSE-51. 36 p.
Komarek, E. V. Sr. Fire and Man in the Southwest.
Proceedings of the Symposium on Fire Ecology and
the Control and Use of Fire in Wildland Management. 1969 April; Tucson, Arizona, 17 p.
Schroeder, M.J. and others. Symoptic Weather
Types Associated with Critical Fire Weather.
Berkeley, Calif.: Pacific Southwest Forest and
Range Exp. Stn.; Forest Serv., U.S. Dep. Agric.
1964: 264-268.
501