Tony Caprio
Corky Conover
Mary Beth Keifer
Pat Lineback
ABSTRACT
With limited funding available for prescribed fire, selecting
critical areas for burning is increasingly important to land management
agencies. This paper presents the process used by Sequoia and
Kings Canyon National Parks to integrate hazard, risk, and value
criteria as they relate to fire planning within a framework of
GIS. Our goal was to identify high priority areas most in need
of burn treatment to optimize the use of limited funding. This
type of use of GIS is classical, but in an area that has received
only minor attention.
This application was completed using ArcInfo, Grid, and ArcView
3.0. Three major models were developed. A value model was
developed that considers two major components. First, the ecological
need component considered fire rotations based on historic fire
return intervals (pre 1860) within general plant communities.
The longer a time interval exceeded the maximum historic fire
interval without a fire, the higher the priority rating for returning
fire to this area. The second component of the value model considered
infrastructure and human life/safety values. High visitation areas
and areas with buildings/facilities were given higher weight and
value. A hazard model considered key factors that affect
managers' ability to a control a fire, or a fire's resistance
to control once ignited. Finally, a risk model was developed
that considered historic wildfire occurrence from both human and
lightning causes. These three models can be aggregated together
in different ways depending on the nature of the questions being
asked, or each model can be considered as a separate analysis.
As severe wildfires continue to increase each year in North America
because of continuing fuel accumulation, it will become increasingly
important to use fire as a management option. The use of GIS will
be an essential tool for planning and implementing land management
programs such fuel modification and ecosystem restoration.
Project Area
Sequoia and Kings Canyon National Parks (SEKI), located in the
southern Sierra Nevada, are topographically rugged with elevations
ranging from 1,600 to 14,495 feet. Major drainages are the Kern,
Kaweah, Kings , and San Joaquin Rivers. The park encompasses some
864,383 acres. Three broad vegetation zones dominate the park,
the foothills (1600 to 5000 ft) composed of annual grasslands,
oak and evergreen woodlands, and chaparral shrubland, the mixed-conifer
forest (5000 to 10000 ft) with ponderosa pine and white and
red fir forests, and the high country (10,000 to 14,000
ft) composed of subalpine and alpine vegetation, and unvegetated
landscapes. Within the mixed-conifer zone, well-defined groves
of giant sequoia are found.
Climate is distinctly Mediterranean with cool moist winters and
warm summers with little rainfall (seasonal summer thunderstorms
occur sporadically at higher elevations). Precipitation increases
as elevation increases, to about 40 inches annually from 5-8,000
feet on the west slope of the Sierra, and then decreases as one
moves higher and to the east. Substantial snow accumulations are
common above 5,000 feet during the winter.
European settlement of the area began in the 1860s with extensive
grazing, logging, and mineral exploration. The parks were founded
in 1890, originally with the intent of protecting sequoia groves
from logging, but were expanded to include much of the surrounding
rugged, high mountains.
Historic Fire Regimes
Historically, fire played a key ecological role in most Sierra
Nevada plant communities. At the landscape level, fire history
research shows an inverse relationship between fire frequency
and elevation in areas of mixed-conifer forest (Caprio and Swetnam
1995). Currently, fire history information is lacking for the
foothills area of the park. The cause of fires prior to Euroamerican
settlement is usually attributed to ignitions by lightning or
native Americans. However, since the actual source of these fires
cannot be determined, the specific cause(s) remain largely unknown.
The seasonal occurrence of historic fires was similar to the contemporary
late summer-early fall fire season (Caprio and Swetnam 1995).
The size of historic fires was variable; some were very large
and burned across multiple watersheds (Caprio unpublished data),
while some were restricted to single trees. Fire intensity was
variable both spatially and temporally (Stephenson et al. 1991;
Caprio et al. 1994). In much of the mixed-conifer zone, fires
were primarily non-stand replacing surface fires, although many
exceptions exist (Caprio et al. 1994). Specific regional fire
years have also been identified, when widespread fires occurred
(a result of a single or multiple starts), usually during dry
years (Swetnam et al. 1992).
Fire regimes in the Sierra Nevada changed dramatically beginning
with Euroamerican settlement around 1860-1870 (Kilgore and Taylor
1979, Caprio and Swetnam 1995). Factors that contributed to this
decline in fires during the latter portion of the nineteenth century
include the loss of native American populations that used fire
and heavy livestock grazing that reduced herbaceous fuels available
for fire spread (Caprio and Swetnam 1995). The occurrence of fires
of large size decreased dramatically during the twentieth century
because of active fire suppression. This change in fire regime
has lead to unprecedented fuel buildups in many plant communities,
structural and composition changes, and has resulted in an increased
probability of widespread high intensity burns.
Fire as a Tool
Most land management agencies classify fires as either a "suppression
fire" or a "prescribed fire". The prescribed fire
category is further broken down into prescribed natural fires
(PNF), ignited naturally by lightning (unplanned ignitions), or
management ignited prescribed fires (MIPF; planned ignitions).
This paper focuses on the use of planned ignitions to achieve
land management goals.
Land management agencies intentionally ignite fires for a variety
of reasons, including some of the following: fuel reduction for
resource protection, site preparation, thinning, elimination of
undesirable species, protection of desirable species, and reintroduction
of fire as a natural process. Agencies with large land areas are
most interested in fire as a natural process. In recent years,
federal land management agencies have begun to re-emphasize the
return of fire to the ecosystem. Reintroducing fire as a natural
process after nearly a century of fuel accumulation will not be
easy for many reasons. Some issues include difficulties in fire
control and associated costs, unnatural or unwanted fire effects,
and social acceptance of fire. Despite these issues, planned ignitions
will be a key tool for putting fire back into the ecosystem (Federal
Wildland Fire Management Policy and Program Review 1995).
MODELS
Value Model
The value model was divided into two components: ecological need
and life safety/infrastructure.
Ecological Need Component
The motivation for an ecological need component was based on the
National Park Service's mission statement to "protect and
preserve" natural resources. Fire is an important process
and component for working towards this goal.
The ecological need component provided a rating index to rank
areas for the need to burn. All areas within the parks' 11 broad
vegetation classes were rated based on fire return interval
departures. This rating permitted us to assign priorities
based on ranks for all areas in our model. A specific value for
each area's fire return interval departure was based on
the time since the last fire (TSLF), relative to the maximum average
fire return interval (RImax) prior to Euroamerican
settlement for each vegetation type. The historic fire regime
return interval values (Table 1) were based on reconstructed fire
history chronologies derived from tree-ring samples obtained from
fire-scarred trees in the vicinity of SEKI, or from the literature
if the information for a vegetation type did not exist from within
or near the park (Caprio in prep.). To provide a conservative
estimate, we used the maximum average return interval for each
vegetation class (RImax). The TSLF was derived from
historic fire records (these extend back to 1921) or based on
the last widespread fire date recorded by the fire history reconstructions.
Based on the fire history chronologies, the year 1899 was chosen
as a conservative base year for the occurrence of the last fire,
for all areas where no recent historic fires (since 1921) have
occurred.
Table 1. Maximum average return intervals for
vegetation classes.
1 - Ponderosa Mixed Conifer | 6 |
2 - White Fir Mixed Conifer | 16 |
3 - Red Fir Mixed Conifer | 50 |
4 - Lodgepole Pine Forest | 163 |
5 - Xeric Pine Forest | 50 |
6 - Subalpine Conifer | 508 |
7 - Foothills Hardwood & Grassland | 17 |
8 - Foothills Chaparral | 60 |
9 - MidElevation Hardwood | 23 |
10 - Montane Chaparral | 75 |
11 - Meadow | 65 |
Using these inputs, a derived index was calculated to quantify
the departure of the vegetation type from its pre-Euroamerican
settlement fire return interval. The equation for the index is:
Fire Return Interval Departure = RImax - TSLF
RImax
where,
RImax = maximum average return interval for vegetation classification,
and,
TSLF = (time since last fire) time that has passed since the most
recent fire from historic fire records or using the baseline date
of 1899 derived from the fire history chronologies.
The departure index ranges from -16 to 1 given our data set with a beginning TSLF of 1899 and a minimum RImax value of 6. We reclassed the index values into four rating categories that we felt captured current forest conditions and the need for burning based on historical fire intervals (Table 2).
Table 2. Fire return interval departure index for each
ecological need category.
Using this component of the model, these categories were mapped
spatially across the parks using GIS. While the dominant ecological
need category was "moderate" (Table 3), the "extreme"
and "high" categories are most important in the lower
elevation conifer forests, an area of high visitor use.
Table 3. Summary of acreage by fire return interval for each
ecological need category.
Infrastructure and Life/Safety Component
In this component of the value model, we addressed the anthropogenic
and natural resources on the landscape that could potentially
be impacted by fire. The component included two factors: infrastructure
values, and human life/safety values. Each factor was divided
into three categories: high, moderate, or low, based on a number
of criteria (Table 4 and Table 5).
Table 4. Infrastructure values: criteria as they relate
to replacement costs or disruption of services.
developed sites, power/phone lines, electronic sites, pipelines | campgrounds, picnic areas, maintained roads | trails, vistas, overlooks, fences, backcountry camp sites |
Table 5. Life/safety values: criteria for developed areas
as they relate to the threat to human life from fire.
Bearpaw High Sierra Camp, Oriole Lake, Atwell Area, Cabin Cove Area, Silver City Area,Giant Forest Area, Ash Mountain Area, Crystal Cave Area, Crystal Cave Road, Mineral King Road, General Hwy from Hospital Rock to Eleven Range | Grant Grove Area, Red Fir Area, Lodgepole Area, Wuksachi Area, Dorst Campground, Faculty Flat Area, Generals Hwy from Eleven Range to Grant Grove | Cedar Grove Area, Mineral King Valley Area |
Hazard Model
In the hazard model we examined key parameters that affect managers'
ability to control fire (ie. resistance to control). The four
parameters were, 1) fuel model, 2) slope, 3) elevation, and 4)
aspect. Slope, aspect, and elevation were derived from a digital
elevation model (DEM). The fuel models used were the thirteen
standard fuel models for fire behavior estimation (Albini, 1976).
Future updates of the model will probably include site specific
"custom models" (Burgan and Rothermel, 1984). Each of
the four parameters was divided into three categories: high, moderate,
or low, based on specific elements within each parameter (Table
6). Applying this model using GIS indicated that the largest portion
of the parks was in the low hazard category and the smallest portion
was in the high category (Table 7).
Table 6. Hazard model parameters, ratings, and individual
elements within each parameter.
Fuels
Slope
Elevation
Aspect
Table 7. Acres in each hazard rating within the parks.
Risk Model
In the risk model we identified the risk of potential ignitions
by looking at the historic occurrence of both human and naturally
(ie. lightning) caused fires. We divided the parks into watersheds
and plotted the occurrence of reportable fires over the last ten
years of record. The data for each watershed was analyzed and
classified into areas of high, moderate, and low risk. A ratio
was developed for the number of ignitions/1000 acres for each
watershed to allow a comparison between watersheds. A key assumption
in the risk model was that locations where fire ignitions have
historically occurred will continue to be sources of ignition.
SUMMARY
The framework presented for the development of GIS models for
prioritizing fire planning needs produce simple, color-coded ratings
viewed on park maps for each of the model components. In this
way, the areas with the highest priority ratings based on either
value, hazard, or risk can be viewed spatially when determining
which areas to focus planned ignition efforts. Depending on the
program goals and questions asked, the models can be used separately
or integrated, using either overlays or by combining model algorithms
to produce single maps of a combination of models. Other applications
for this framework include: fire prevention planning, fire preparedness
planning, and use in National Environmental Policy Act (NEPA)
compliance documents.
FUTURE MODEL CONSIDERATIONS
As these models evolved and developed, potential improvements
were identified in the form of model validation, improved source
data, and model refinement. Some of the planned changes include
the following:
ACKNOWLEDGEMENTS
We would like to thank the staff of Sequoia and Kings Canyon National
Parks, including Jeff Manley, Bill Kaage, Scott Williams, Linda
Mutch, Ed Nelson, and Dan Buckley, whose collective effort and
input has made this project possible.
REFERENCES
Albini, Frank A., 1976. Estimating wildfire behavior and effects.
USDA For. Serv. Gen. Tech. Rep. INT-30, 92 p. Intermountain Forest
and Range Experiment Station, Ogden, Utah.
Burgan, Robert E.; Rothermel, Richard C. BEHAVE: Fire Behavior
Prediction and Fuel Modeling System - FUEL Subsystem. USDA For.
Serv. Gen. Tech. Rep. INT- 167, 126 p. Intermountain Forest and
Range Experiment Station, Ogden, Utah.
Caprio, A.C., L.S. Mutch, T.W. Swetnam, and C.H. Baisan. 1994.
Temporal and spatial patterns of giant sequoia radial growth response
to a high severity fire in A.D. 1297. Final Report of California
Department of Forestry and Fire Protection, Mountain Home State
Forest, Contract No. 8CA17025, Laboratory of Tree-Ring Research,
University of Arizona, Tucson.
Caprio, A.C. and T.W. Swetnam. 1995. Historic fire regimes along
an elevational gradient on the west slope of the Sierra Nevada,
California. In: J.K. Brown, R.W. Mutch, C.W. Spoon, R.H. Wakimoto
(tech. coord.). Proceedings: Symposium on Fire in Wilderness
and Park Management: Past Lessons and Future Opportunities, March
30-April 1, 1993, Missoula Montana. USDA Forest Service, INT-GTR-320.
Kilgore, B.M. and D. Taylor. 1979. Fire history of a sequoia mixed-conifer
forest. Ecol. 60:129-142.
Stephenson, N.L., D.J. Parsons, and T.W. Swetnam. 1991. Restoring
natural fire to the Sequoia-mixed conifer forest: should intense
fire play a role? In: 17th Proceedings of the Tall Timbers
Fire Ecology Conference, pp. 321-337.
Swetnam, T.W., C.H. Baisan, A.C. Caprio, R. Touchan, and P.M.
Brown. 1992. Tree-ring reconstruction of giant sequoia fire regimes.
Final report to Sequoia, Kings Canyon and Yosemite National Parks,
Laboratory of Tree-Ring Research, Tucson, AZ. 90 pp. + appendices.
USDI and USDA. 1995. Federal Wildland Fire Management Policy and
Program Review. Final Report.
Tony Caprio
Ecologist
Sequoia and Kings Canyon National Parks
Three Rivers, CA 93271
phone: 209.565.3725
fax: 209.565.3730
email: tony_caprio@nps.gov
Corky Conover
Ecologist
Sequoia and Kings Canyon National Parks
Three Rivers, CA 93271
phone: 209.565.3129
fax: 209.565.3730
email: clarence_m_conover@nps.gov
Mary Beth Keifer
Ecologist
Sequoia and Kings Canyon National Parks
Three Rivers, CA 93271
phone: 209.565.3128
fax: 209-565.3730
e-mail: marybeth_keifer@nps.gov
Pat Lineback
GIS Coordinator
Sequoia and Kings Canyon National Parks
Three Rivers, CA 93271
phone: 209.565.3725
fax: 209.565.3730
email: pat_lineback@nps.gov