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Workshop Summary: Who Cares About Fire History?
Robert W. Mutch
INTRODUCTION
Threads of continuity ran through this excellent workshop. The workshop was characterized by
an abiding interest in a common terminology, concern
about scale (how large, or small, an area can be
represented), the resolution of data required to
make effective management decisions, recognition
of the limitations of fire history information, the
cultural, biological and environmental stratification of data, and animated discussions regarding
differing methodologies. These threads wove a unifying strength into the workshop's fabric. But
some of the participants harbored reservations
about the utility of fire history information;
thus, the question: Who cares about fire history?
This questioning remark was overheard during one
of the informal discussion periods, and it is an
appropriate one to ask.
Certain factors limit the interpretation and
application of fire history information and pose
potential reasons for not caring:
Flammable exotic species tend to obscure
"natural" fire frequencies (e.g., Bromus
rubescens in Sonoran Desert, Bromus
tectorum in Great Basin, Mela~in
Everglades) •
2.
Changing cultural activities over time
confound the "natural" fire history
record (e.g., burning by aboriginals,
miners, trappers, settlers).
3.
Climatic changes occur.
4.
Grazing patterns change.
5.
Fire scars represent a conservative
history (fires must be intense enough
to scar the cambium tissue).
2
6.
Stratification of data is sometimes difficult.
1.
It is difficult to date events in certain
ecosystems (for example, fires in the
Sonoran Desert leave few direct signs).
8.
Fire chronologies that are not cross-dated
may impair the accuracy and amount of information collected.
9.
The importance of fire history information
to fire suppression, prescribed fire, and
land management planning programs is not
fully recognized.
For these reasons, and possibly others, it
would be easy to discount the importance of fire
history studies. Despite these limitations, workshop participants did care about fire history information and its application to management programs.
Fire history results were reported from northern
Quebec to the Northwest Territories, New England
and Florida to Oregon and California, and from
Sweden and Australia.
APPARENT LIMITING FACTORS
1.
1
FIRE HISTORY METHODOLOGIES
Many methods were presented to determine the
fire history of a point or area, including the direct dating of fire scars in the annual rings of
trees and numerous indirect procedures. Direct
dating techniques essentially followed the crossdating methods developed by the Laboratory of TreeRing Research, University of Arizona, or utilized
an alternative method as described by Steve Arno
and Kathy Davis. Lake sediment analyses for pollen
and charcoal provided additional direct, but less
precise, estimates of fire intervals. Indirect
methods for determining fire history analysis included land survey records, informants, journals,
and fire occurrence records, inferences derived
from the adaptive strategy of species, and age
class distributions of fire originated stands.
QUESTIONS AND CONCEPTUAL CHALLENGES
1Prepared for the Fire History Workshop,
Laboratory of Tree-Ring Research, University of
Arizona, Tucson, Arizona, October 20-24, 1980.
2Fire Management Officer, Lolo National
Forest, Missoula, Montana.
Bill Moir questioned our ability to stratify
fire history information in meaningful ways, demonstrating that if you've seen one canyon woodland
you haven't necessarily seen them all. The issue of
stratification came up repeatedly during the workshop. Investigators subdivided time and space in
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terms of prehistoric and historic periods, environmental gradients, and plant communities. Fire
history information obviously will be more readily
extended and applied to resource management programs, if it can be organized according to recognized classification systems. For example, the
interpretation of fire history data in different
environments (through habitat types) has facilitated management applications in the northern
Rocky Mountains.
intervals are around 2 years than in the cedarhemlock stands of northern Idaho where the return
interval can exceed 200 years. On the other hand,
low productive sites characterized by warm-dry and
cold-dry environments should not be as adversely
affected by fire exclusion as moderately productive
sites with frequent fire intervals. Thus, information about fire intervals and productivity is important to the resolution and scheduling of prescribed fire activities.
Fire history and fire ecology relationships
in the east and northeast often have not been
addressed with the detail devoted to our understanding of western ecosystems. It was encouraging to see Craig Lorimer and Serge Payette apply
land survey records and paleoecological methods
to further the understanding of fire in eastern
ecosystems. Lorimer's results suggested a 400- to
800-year fire interval in his study area in the
northeast. Because such an event is infrequent,
does this imply that the effect of that event is
insignificant? Fred Hall tended to contrast understory burning vs. crown fire regimes in a competitive sense, indicating that understory burning is
more important than crown fires. Is it appropriate
to consider one type of fire regime as being more
significant than another type? Or should we recognize that different p~ant communities are regulated
by different intervals, types, and intensities of
fires? Thus, infrequent crown fires are as normal
to lodgepole pine forests as frequent surface fires
are to ponderosa pine forests.
An assumption that stands are uniformly fla~
mable over time does not fit all plant communities.
Contrast the frequent, sometimes almost annual, fire
intervals in ponderosa pine with the more infrequent
intervals in lodgepole pine. And we must recognize,
too, that there is considerable variation in fire
intervals within each of these types with more frequent intervals in western Montana lodgepole pine
as compared to the Yellowstone National Park lodgepole stands. We can use such fire history information to infer relationships about the presence or
absence of fuel-free periods in these plant communities. Such fuel succession information is useful
in defining opportunities for prescribed natural
fire programs. If age class mosaics serve to regulate fire size, this knowledge provides a measure
of confidence that Yellowstone National Park is
large enough to contain fires freely burning under
prescription. Conversely, if we are losing the expression of an age class mosaic as in the chaparral
type of southern California, we can expect an increase in high intensity, large fires (as the 16to 18-year fire interval is dampened by suppression
efforts).
Is it possible to discuss fire history results
in an objective manner? Words like degradation,
disastrous, and damage crept into some of the discussions during the week. Can our interpretations
of fire history be unbiased if we employ such value
judgments in our assessment of fire intervals and
their effects on ecosystems? Shouldn't resource
management objectives provide the criteria for
determining whether a given fire is beneficial or
harmful?
Several investigators appreciated that tree
rings portrayed only a narrow slice out of the time
sequence of a region's fire history. Examples of
paleoecological research were presented that dramatically extended fire history information back
to prehistoric periods. Gurdip Singh presented
some tantalizing results regarding the pollen and
charcoal record in southeastern Australia. Results
such as these should provide us with new insights
regarding the evolutionary adaptedness of plant
communities to varying fire intervals. And although
we should never expect to acquire fire chronologies
that rival the time span encompassed in Wes
Ferguson's bristlecone work, more attention to crossdating would permit us to push fire history informa'tion further back in time.
Fire interval information, when coupled with
the knowledge of a site's productivity, can be
instrumental in evaluating the effects of attempted
fire exclusion actions. The effects of 50 years
of fire suppression will be more readily discernible
in the Arizona ponderosa pine stands where fire
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There may be a new opportunity for real-time
fire history studies in the future, due to the
natural laboratory provided by long duration (up to
5 months) prescribed fires in national parks and
wildernesses. Tommorrow's fire historian has the
chance to live with these fires on a day-to-day
basis, observing which trees are scarred, when
they're scarred, and how they're scarred; and also
observing events that contribute to the nonscarring
of trees. These observations, coupled with the
distribution of fire intensity classes and stand
mosaics associated with individual large fires, could
improve our understanding of fire interactions with
plant communities. Also, the seasonal collection
and analysis of fire-scarred specimens on prescribed
fires might permit us to determine the seasonality
of historic fire occurrence, as well as the year of
occurrence.
MANAGEMENT APPLICATIONS
The workshop described some land managers as
not always being careful, unenlightened, victims
of their own inadequate literature searches, and
guilty of seemingly irrational suppression decisions
in many instances. These perceptions of a manager
need to be interpreted in terms of his environment:
1.
Subject to endless deadlines.
2.
Accountability for hard targets and
planned accomplishments.
3.
A daily schedule driven by phone calls
and a steady stream of mail with due
dates.
4.
Often a crisis-oriented decisionmaking
atmosphere.
5.
Too little time to read and reflect.
6.
A sincere desire to do better (which
means applying our current knowledge
base in the decision making process).
7.
SUMMARY
The purpose of the workshop was to exchange information on sampling procedures, research methodology, preparation and interpretation of specimen
material, terminology, and the application and significance of findings. That Marv Stokes and Jack
Dieterich were right on target in providing a productive forum for such discussions is best exemplified in the remarks of the participants themselves.
Many felt that it was one of the most informative
workshops they had ever attended. Those in attendance also agreed that the pace was quick, and that
energy levels remained high. Challenging discussion punctuated the delivery of diverse and stimulating papers as people freely shared ideas with
each other. And the warm hospitality of the faculty and staff of the Laboratory of Tree-Ring Research
provided a comfortable environment for communications.
To the question, "Who cares about fire history?," many managers today would respond with an
"I care!" Fire Management policies today are more
closely aligned with the resource objectives of
agencies like Parks Canada, National Park Service,
Bureau of Land Management, and USDA Forest Service.
As imprecise as fire history information may be,
an increasing number of enlightened land managers
consider it to be absolutely essential, not just
"nice to know", data for land management planning
purposes. Researchers and m anagers need to
acquire the necessary patience and perseverance
to work closely with each other. Just because a
study is published and distributed to library and
office shelves is no guarantee that the information
will be applied. Effective application.will be
realized only when the researcher and manager
agree to meet each other more than half way. In
other words, each must have the desire to live a
little in the other's world.
One of the objectives of the workshop was to
emphasize the relationship of dendrochronology
procedures to fire history studies and interpretations. Although his outward demeanor was calm,
Marv Stokes must have been inwardly wincing at the
absence of cross-dating procedures in some of the
tree-ring investigations. Lively debates ensued
regarding the need for cross-dated chronologies in
all cases. And Tom Harlan provided the group a
moment's pause when he indicated that it could take
up to a year for a person to develop competency in
dendrochronology procedures. Yet the participants
went away with a better appreciation for the increased accuracy and information content that results when standard dendrochronology methods are
followed. More than one individual indicated an
interest in developing cross-dated chronologies
in future studies.
Some of the practical applications of fire
history information as stated by Kathy Davis and
others are:
1.
A basis for silvicultural prescriptions.
2.
A basis for fire behavior predictions on
wildfires.
3.
A data base for land management planning.
4.
A scheduling guide for prescribed burning
activities to simulate natural intervals
(some warning signals to observe when we
exclude fire for too long, or return it
too frequently).
5.
6.
A backdrop to guide development of postfire rehabilitation programs. Fire history and fire effects information demonstrate that fire adapted plant communities
have evolved mechanisms to rehabilitate
themselves; and that massive re-seeding
programs often can be avoided.
\
Most tree-ring investigators stated that they
were essentially forced to take material wherever
they found it and were unable to follow a rigid
sampling design. One saving point is that a few
trees seem to capture most of a stand's fire history story. But there's probably a need to better
involve biometricians to strengthen sampling procedures where possible.
An aid in prescribed burning and prescribed natural fire planning (effects
of past fire exclusion related to different fire intervals, public understanding
of prehistoric and historic role of fire,
potential fire intervals and fire sizes,
etc.). Steve Barrett provided evidence
to consider aboriginal burning as a
measurable element in natural ecosystems.
A final footnote is in order--and that has to
do with the warm kinship the workshop participants
all felt towards Harold Weaver and his lovely wife,
Billie. Having this grand gentleman of"ponderosa
pine management with us all week added immeasurably
to the workshop's atmosphere. Thanks to both of
you for joining with us and for giving us the
opportunity to get to know you better.
An example to gain homeowner's attention
to the fact that fires are inevitable in
most plant communities. The fire history
record indicates that although we may
postpone fires we will not eliminate
them from the urban/wildland interface.
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