D. McKenzie et al. (eds.), The Landscape Ecology of Fire, Ecological Studies 213,
DOI 10.1007/978-94-007-0301-8_10, © Springer Science+Business Media B.V. 2011
Planning and management for the expected effects of climate change on natural
resources are just now beginning in the western United States (U.S.), where the
majority of public lands are located. Federal and state agencies have been slow to
address climate change as a factor in resource production objectives, planning
strategies, and on-the-ground applications. The recent assessment by the
Intergovernmental Panel on Climate Change (IPCC 2007) and other high-profile
reports (e.g., GAO 2007) have increased awareness of the need to incorporate cli-
mate change into resource management.
Most of the recent literature on adaptation to climate change has focused on
conceptual issues (Hansen et al. 2003), potential actions by local governments and
municipalities (Snover et al. 2007), and individual resources and facilities
(Slaughter and Wiener 2007). However, efforts to develop strategies that facilitate
adaptation to documented and expected responses of natural resources to climate
change are now beginning in earnest. For example, the Chief of the U.S. Forest
Service recently stated that addressing climate change is one of the top three priori-
ties of the agency (Kimbell 2008). In the most substantive effort to date, the U.S.
Climate Change Science Program has developed synthesis and adaptation products
for federal land management agencies (Joyce et al. 2008).
The frequency, severity, and extent of wildfire are strongly related to climate
(Swetnam and Betancourt 1990; Johnson and Wowchuk 1993; Stocks et al. 1998;
Hessl et al. 2004; Gedalof et al. 2005; Heyerdahl et al. 2008; Skinner et al. 2008;
Taylor et al. 2008; Littell et al. 2009). Increasing temperatures with climate change
D.L. Peterson (*)
Pacific Wildland Fire Sciences Laboratory, Pacific Northwest Research Station,
U.S. Forest Service, Seattle, WA 98103-8600, USA
Managing and Adapting to Changing
Fire Regimes in a Warmer Climate
David L. Peterson, Jessica E. Halofsky, and Morris C. Johnson
250 D.L. Peterson et al.
will likely lead to changes in fire regimes in many types of ecosystems (IPCC
2007). Increased spring and summer temperatures with climate change will lead to
relatively early snowmelt (Stewart et al. 2005; Hamlet et al. 2007), lower summer
soil moisture (Miles et al. 2007) and fuel moisture (Westerling et al. 2006), and
longer fire seasons (Wotton and Flannigan 1993; Westerling et al. 2006). These
conditions will lead to increased fire frequency and extent (Price and Rind 1994;
Gillett et al. 2004; Westerling et al. 2006, Chap. 5). McKenzie et al. (2004) found
that for a mean temperature increase of 2°C (expected by mid-twenty-first century),
annual area burned by wildfire is expected to increase by a factor of 1.4–5 for most
western U.S. states. Dry fuel conditions associated with increased temperatures
allow forests to burn whenever an ignition source occurs, with low humidity and
high winds contributing to fire spread.
Climate change will alter the effectiveness of fire and fuel management, and there-
fore necessitates that we adapt how we manage fire and fuels. There are well estab-
lished scientific principles of fuels management upon which we can rely to inform
future strategies. These strategies need to be applied to large landscapes, which are
the land units for which managers are responsible and across which fires spread.
Adaptation to changing fire regimes and other ecological effects of climate change
will help reduce ecosystem vulnerabilities and potentially undesirable effects on
ecosystem composition, structure, and function (Millar et al. 2007; Joyce et al. 2008).
Adapting management to changing fire regimes will likely be a major challenge
for resource managers in the face of climate change. This chapter outlines general
adaptation strategies and specific fire and fuel management options for forest
managers under climate change, primarily for dry forests with low-severity and
mixed-severity fire regimes (e.g., pinyon pine-juniper [Pinus spp., Juniperus spp.],
ponderosa pine [Pinus ponderosa], dry Douglas-fir [Pseudotsuga menziesii],
mixed conifer, mixed evergreen). We first present strategies and options from the
perspective of managers and then expand on some of these from the perspective of
10.2 Adapting to the Effects of Climate Change
We initiated science-management collaborations at Olympic National Forest
(Washington, USA) and Tahoe National Forest (California, USA) to develop man-
agement options that will facilitate adaptation to climate change (Littell et al. N.d.).
This was the first attempt to work with national forests to develop specific concepts
and applications that could potentially be implemented in management and planning.
The focus of this effort was to develop strategies and management options for
adapting to climate change across multiple resources, and there was no intention to
specifically focus on fire or fuels management. In this chapter, we build on this
foundation of general concepts by identifying strategies and management options
relevant for managing changing fire regimes across large landscapes.
25110 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
10.2.1 General Adaptation Strategies
The national forests developed six general adaptation strategies (Table 10.1; Littell
et al. N.d.) in response to climate change. We have amended these strategies to
emphasize their relevance for landscape fire and fuels management in a changing
Manage for resilience, decrease vulnerability–Fire exclusion has increased •
understory vegetation and surface fuels in many forests, making them vulnerable
to crown fire should wildfire occur. Managing for reduced understory and sur-
face fuels will increase resilience to fire and favor retention of large trees (Dale
et al. 2001; Peterson et al. 2005; Joyce et al. 2008). Thinning, surface fuel
removal (mechanically or through prescribed burning), and allowing naturally
ignited fires to burn (rather than suppressing them) can reduce fuels across
sufficient areas to reduce the severity of future wildfires.
Prioritize climate-smart treatments—Managers have many choices for treating •
landscapes, but typically have minimal financial and human resources, so priori-
tizing treatments that are likely to work in a warmer climate may become increas-
ingly necessary (Millar et al. 2007). For example, stand densities may need to be
lower in the future to reduce the risk of overstory mortality if fire weather will be
Table 10.1 Summary of general adaptation strategies, and examples of applying those strategies
to changing ﬁre regimes
Adaptation strategy Examples of application to changing fire regimes
Manage for resilience,
Reduce stem density and surface fuel in stands where fire
exclusion has created vulnerability to crown fire
Implement fuel treatments across large landscapes in order to
modify fire severity and spread
Design fuel treatments to be resilient to intense fire behavior
that may accompany extreme fire weather in the future
Consider tradeoffs and
Identify how fuel treatments may affect carbon dynamics,
hydrology, and wildlife habitat at various spatial and
Manage dynamically and
Implement various types and intensities of fuel treatments
at different spatial and temporal scales and evaluate their
effectiveness for reducing crown fire
Manage for process Plan for the regular occurrence of wildfire at different spatial
and temporal scales, rather than only suppressing fire or
considering it to be an anomaly
Manage for realistic
Plan for the regular occurrence of fire, not elimination of fire
in wildland-urban interface areas
Develop collaborative management between public land
managers and local residents to modify fuels sufficiently
to reduce fire severity if wildfire occurs and to facilitate
252 D.L. Peterson et al.
more extreme (Dale et al. 2001; Spittlehouse and Stewart 2003). Reduced stand
densities would also increase resistance to drought and insect attack.
Consider tradeoffs and conflicts—Future effects on ecological and socioeco-•
nomic sensitivities can result in potential tradeoffs and conflicts for species
conservation and other resource values. For example, forest landscapes with
periodic thinning and surface fuel treatments may have different carbon dynam-
ics than landscapes without active management in which crown fires would be
more likely to occur (Millar et al. 2007; Hurteau et al. 2008).
Manage dynamically and experimentally—Currently available opportunities •
(i.e., under current policy) can be used to implement adaptive management over
several decades (Dale et al. 2001). For example, different types and intensities
of fuel treatments can be used over time and space in order to determine their
effectiveness for reducing crown fire.
Manage for process—Project planning and management can be used to maintain •
or enhance ecological processes rather than to design specific structures or spe-
cies composition (Harris et al. 2006). For example, novel mixes of species and
spacing can be used following fire in order to reflect likely natural dynamic
processes of adaptation.
Manage for realistic outcomes—Projects that are currently a component of the •
planning process may have a higher failure rate in a warmer climate, and it will
become increasingly important to assess the viability of management goals and
desired outcomes (Hobbs et al. 2006). For example, it will never be possible to
eliminate fire from wildland-urban interface areas, but land managers can work
with local residents to reduce fire hazard to a level that may allow suppression
to be effective there, while allowing fire to play a less managed role in other
parts of the landscape.
10.2.2 Specific Adaptation Options
The national forests developed nine specific adaptation options (Table 10.2). In
contrast to the guiding principles provided by general strategies above, adaptation
options refer to specific kinds of actions that can be taken at a variety of spatial
scales. We have amended the discussion to emphasize the relevance of those
options for fire:
Increase landscape diversity—This option focuses on increasing variety in stand •
structures and species assemblages over large areas and avoiding “one size fits
all” management prescriptions (Millar et al. 2007). This can include applying
forest thinning to increase variability in stand structure, increase resilience to
stress by increasing tree vigor, and reduce vulnerability to disturbance (Parker
et al. 2000; Dale et al. 2001; Spittlehouse and Stewart 2003). Although there is
no theory or empirical data at the present time to guide which combinations of
stand structures and species will optimize adaptation potential, allowing fires to
burn unsuppressed may in some cases help to emulate landscape patterns that
25310 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
existed during pre-settlement times (Hessburg and Agee 2003). These patterns
from natural experiments may hold the greatest adaptation potential.
Maintain biological diversity—Appropriate species and genotypes can be •
planted in anticipation of a warmer climate (Smith and Lenhart 1996; Parker
et al. 2000; Noss 2001; Spittlehouse and Stewart 2003; Millar et al. 2007), giving
more flexibility by diversifying the phenotypic and genotypic template on
Table 10.2 Summary of speciﬁc adaptation options developed by national forests, and examples
of applying those options to changing ﬁre regimes
Adaptation option Examples of application to changing fire regimes
Increase landscape diversity Thin forest stands to create lower density, diverse stand
structures and species assemblages that reduce fire
hazard, increase resilience to wildfire (allow overstory
survival), and increase tree vigor by reducing competition
Maintain biological diversity Plant nursery stock from warmer, drier locations than what is
prescribed in genetic guidelines based on current seed zones
Plant mixed species and genotypes, with emphasis on fire
resistant species and morphology
Increase resilience at large
Implement thinning and surface fuel treatments across large
portions of landscapes (e.g., large watersheds) where large
wildfires may occur
Orient the location of treatments in sufficiently large blocks to
modify fire severity and fire spread
Treat large-scale disturbance
as a management
Develop plans for management objectives and activities
following large fires, including long-term experimentation
Focus the spatial scale of management on units (or aggregated
units) of hundreds to thousands of hectares in appropriate
Implement fuel treatments across large units and blocks of land
to more effectively reduce fire severity and spread
Implement early detection/
rapid response for invasive
Survey and monitor vegetation following wildfire in order to
detect and eradicate undesirable invasive plant species
Match engineering of
infrastructure to expected
Modify drainage systems (e.g., install larger culverts) to
accommodate higher water flow resulting from more
Design road systems to facilitate efficient fire suppression
Collaborate with a variety of
Develop mutual plans for fire and fuels management with
adjacent landowners to ensure consistency and effectiveness
across large landscapes
Promote education and
awareness about climate
Facilitate discussion among management staff regarding the
effects of a warmer climate on fire and interactions with
Educate local residents about how a warmer climate will
increase fire frequency, fuel reduction can protect property
and collaboration with public land managers will assist
broader fuel management objectives
254 D.L. Peterson et al.
which climate and competition interact, and to avoid widespread mortality at the
regeneration stage. For example, nursery stock from warmer, drier locations than
what is prescribed in genetic guidelines based on current seed zones can be
planted following a crown fire (Spittlehouse and Stewart 2003).
Increase resilience at large spatial scales—Proactive management can improve •
the resilience of natural resources to ecological disturbance and environmental
stressors (Dale et al. 2001; Spittlehouse and Stewart 2003; Millar et al. 2007)
and reduce the number of situations in which land managers must respond in
“crisis mode.” For example, if hazardous fuels reduction and allowing some fires
to burn unsuppressed reduces fire severity over large areas, then postfire soil
erosion can be minimized.
Treat large-scale disturbance as a management opportunity—Large-scale distur-•
bance causes rapid changes in ecosystems, but also provides opportunities to
apply adaptation strategies (Dale et al. 2001; Millar et al. 2007). Carefully
designed management experiments for adapting to climate change can be imple-
mented, provided that plans are in place in anticipation of large disturbances. For
example, one could experiment with mixed-species tree planting after fire even
though the standard prescription might be for a monoculture (Millar et al. 2007).
Management experiments need good statistical design, adequate replication, and
long-term commitment by managers and scientists to maintain a time series of
data that can inform future decisions.
Increase management unit size—Increasing the size of management units to •
hundreds or thousands of hectares across logical biogeographic entities such as
watersheds will improve the likelihood of accomplishing objectives (Smith and
Lenhart 1996). For example, large strategically located blocks of forest land
subjected to fuel treatments will reduce fire spread more effectively than smaller
dispersed units (Finney 2001). At the present time, there is minimal theory or
empirical data to guide the design, size, and spatial patterns of management
units, although a closer approximation of patch size created by natural distur-
bances may be a good place to start.
Implement early detection/rapid response for invasive species—A focus on •
treating small problems before they become large unsolvable problems recog-
nizes that proactive management is more effective than delayed implementation
(Millar et al. 2007). For example, recently burned areas are often susceptible to
the spread of invasive species, which can be detected by monitoring during the
first two years after fire (Chap. 8).
Match engineering of infrastructure to expected future conditions—This refers •
primarily to road and drainage engineering that can accommodate future changes
in hydrology (Spittlehouse and Stewart 2003). However, it might be possible to
design road networks to facilitate effective fire suppression in areas that are
particularly fire prone.
Collaborate with a variety of partners—Working with a diversity of landowners, •
agencies, and stakeholders will develop support for and consistency in adapta-
tion options. For example, national forest managers can work with adjacent state
forest managers to agree on fuel treatment plans across large landscapes.
25510 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
Promote education and awareness about climate change—It is critical that internal •
and external education on climate change is scientifically credible and consistent
(Spittlehouse and Stewart 2003), with emphasis on the role of active manage-
ment in adaptation. For example, local residents can be informed that wildfire
may be more frequent in a warmer climate, which makes it imperative that they
clear brush around homes to reduce fire hazard.
Effective landscape fire and fuel management will require that we consider the
potential effects of climate change and adjust activities accordingly. Much of
the current dialog among scientists and resource managers about adapting to
climate change in general is relevant and applicable to landscape fire and fuel man-
agement. Despite considerable uncertainty about the effects of climate change,
scientific foundations for adaptation are sufficiently developed to begin the adapta-
tion process. By taking an experimental and learning approach to management it
will be possible to be both adaptive and responsive.
10.3 Fuels Management in a Warmer Climate
The expected warming in climate may have implications for the design of fuel treat-
ments in dry forests across the western United States. Climate change will influ-
ence fire behavior by increasing temperature, an important factor that controls fire
behavior. Temperature regulates several variables that control fuel flammability:
relative humidity of the atmosphere, moisture content of dead and live fuel, and
wind speed and direction in mountainous terrain (Brown and Davis 1973). Foliar
moisture controls fire behavior and thresholds for crown fire initiation (Agee et al.
2002). For example, a closed-canopy stand is typically cooler and has higher
humidity than an open stand. These characteristics retain dead and live fuel mois-
ture, which regulates surface fuel temperature and wind speeds (Whelan 1995),
although closed-canopy stands often have low canopy base height and high canopy
bulk density, both of which increase the probability of crown fire initiation. On the
other hand, lowering tree density decreases the probability of crown fire initiation,
but may exacerbate fire behavior because solar radiation to the forest floor can
desiccate dead and live fuels (Agee and Skinner 2005).
Based on these considerations, fuel treatment guidelines for restoring the resil-
ience of dry forest ecosystems (e.g., Peterson et al. 2005) may need to be adjusted
to retain either more or fewer stems per hectare (Harrod et al. 1999; Arno and
Allison-Bunnell 2002; Johnson 2008). Forest managers may want to weigh the
tradeoffs related to each strategy for their particular project (Peterson and Johnson
2007) and decide which treatment is feasible for addressing the effects of a warmer
climate on fuels and fire hazard. Understanding basic concepts of fuels and how to
manage them for landscape resilience, and having a way to evaluate effectiveness
of fuel treatments, is a good combination for sustainable management at large
256 D.L. Peterson et al.
10.3.1 Fuel Concepts and Fire Resilience
Fuel is a critical component of both the combustion triangle (fuel, oxygen, heat)
and the fire behavior triangle (weather, fuel, topography), which are conceptual aids
for understanding the principles of combustion and the elements that influence fire
behavior and intensity (Brown and Davis 1973; Pyne et al. 1996). Fuel is classified
by its vertical distribution (ground, surface, or aerial) and its general properties
within a stand (Ottmar et al. 2007). Ground fuels (e.g., decomposing organic
matter, rotting logs) have little influence on wildfire spread. Fire spreads primarily
in the surface fuels, which include seedlings and saplings (i.e., trees less than 1.8 m
tall), shrubs, herbaceous vegetation, litter, and dead woody material (Brown and
Davis 1973). Aerial or crown fuels are composed of live and dead vegetation.
Collectively, these fuel layers are referred to as a fuelbed, which represents the
average physical characteristics of a relatively homogeneous unit on a landscape
with distinct fire environments (Sandberg et al. 2007). Dead woody fuel is classi-
fied by fuel moisture time lags (Fosberg and Deeming 1971). In general, small
diameter fuels have short time lags and are responsible for fire spread rates. Large
diameter fuels have longer time lags and are involved primarily in smoldering. The
type of fuel within a fuelbed strongly influences the intensity of wildfire.
The scientific basis for using fuel treatments to maintain or restore resilience to
wildfire in dry forests is well established (Peterson et al. 2005) and has provided
support for thinning and surface fuel treatments throughout western North America
(Fig. 10.1), including for adaptation to a warmer climate (Joyce et al. 2008). Agee
and Skinner (2005) developed four principles of a fire-safe forest: (1) reduce sur-
face fuels, (2) increase height to live crown, (3) decrease crown bulk density, and
(4) retain large trees (Table 10.3). Surface fuels can be reduced with treatments
such as prescribed fire, pile and burn, and whole-tree harvest. Increasing the height
to live crown and decreasing crown bulk density can be achieved by thinning from
below (progressively removing trees with the smallest diameter). Fuel reduction
treatments designed to leave the large fire resistant trees fulfill the fourth principle
of a fire-safe forest. Agee and Skinner (2005) concluded that forests treated accord-
ing to these principles will be more resilient to wildfires in a warmer climate. In
some cases, it may be possible to accomplish fire-safe principles by allowing wild-
fires to burn unimpeded through areas that have not burned for decades (Miller
et al., Chap. 11), although postfire stem density, quantity of fuel removed, and
spatial patterns of altered stand and fuel structure cannot be controlled.
Although resilience to fire can be enhanced with fuel treatments, climate is a
major driver of fire regimes (Gedalof et al. 2005; Littell et al. 2009, Chap. 5), and
fuel treatment effectiveness is reduced when fires burn under severe conditions
(high temperature, high wind speed, low humidity). In some cases, the influence of
climate on fire could override fuel treatments, resulting in high-severity fire even in
areas where fuels have been reduced. The relative influence of climate versus fuels
on fire regimes is specific to the type of ecosystem being considered. For example,
boreal forests and subalpine forests typically have fuel loadings that are sufficiently
25710 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
Fig. 10.1 Removal of smaller trees and surface fuels can potentially reduce the severity of fire
behavior and effects in a wildfire. Reduction of stand density and surface fuels is shown in these
photos of a ponderosa pine stand on the Lassen National Forest, California, before and after treat-
ment. Lower stand densities and fuels can enhance resilience to fire in a warmer climate by reducing
risk of crown fire and protecting overstory trees and forest structure. Photos courtesy of Lassen
258 D.L. Peterson et al.
high to carry fire and potentially propagate crown fires, but high temperature and
low humidity are necessary to dry the fuels so they can burn; therefore, climate
limits fire regimes in these forests. In contrast, ponderosa pine forests in the
American Southwest are hot and dry every summer, but must have sufficient sur-
face fuels to carry fire; therefore, fuels limit fire regimes in these forests.
Understanding differences in these relative influences among ecosystems will help
to develop and evaluate effective fuel management prescriptions.
10.3.2 Evaluating Effectiveness with Fire Simulation Models
Fire simulation models are valuable for testing the efficacy of fuel treatments,
especially given the logistic challenges of conducting large-scale field experiments
(Andrews and Queen 2001). For example, Johnson (2008) simulated the effects of
thinning and surface fuel treatments on fire hazard using the Fire and Fuels
Extension to the Forest Vegetation Simulator (FFE-FVS: Reinhardt and Crookston
2003) on 45,162 stands from dry forests in the western United States. Treatments
were patterned after Agee and Skinner’s (2005) principles of a fire-safe forest.
Stands were evaluated for four thinning densities (125, 250, 500, and 750 trees per
hectare [tph]), three surface fuel treatments (leave slash, extract slash, prescribed
fire) and no action, resulting in a total of 698,140 projections.
Results indicate that thinning treatments with lower target densities (125 and
250 tph) are more effective at modifying fire behavior than treatments with higher
target densities (500 and 750 tph). These results are consistent with those from
other studies (Stephens 1998; Harrod et al. 1999; Agee et al. 2000; Pollet and Omi
2002; Martinson and Omi 2003; Finney et al. 2005; Stephens and Moghaddas
2005; Cram et al. 2006; Harrod et al. 2007; Strom and Fulé 2007). Arno and
Table 10.3 Principles of ﬁre resistance for dry forests
Principle Effect Advantage Concerns
Fire control easier;
less torching of
less with fire than
Increase height to
Requires longer flame
length to begin
Less torching of
Opens understory; may
allow surface wind to
crown fire less
Reduces crown fire
Surface wind may
increase; surface fuels
may be drier
Keep big trees of Less mortality for
same fire intensity
Less economical; may
keep trees at risk of
Adapted from Agee and Skinner (2005)
25910 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
Allison-Bunnell (2002) suggested that historical surface fire regimes perpetuated
ponderosa pine-dominated stands with 75–250 tph, that is, stands of similar density
to those simulated in Johnson (2008). In other studies, 125 tph represented histori-
cal stands in eastern Washington (Harrod et al. 1999), 100 tph was typical for
Southwestern stands (Covington and Moore 1994), and 150 tph was found in old
Jeffrey pine-mixed conifer forests in the unmanaged Sierra San Pedro Martir
(Mexico) (Stephens and Gill 2005).
Fuel treatment guidelines for dry forests in the western United States have been
developed based on output from the simulation model FFE-FVS (Johnson et al. 2007).
We use an example from that publication—a forest stand in the Okanogan-Wenatchee
National Forest in Washington State—to illustrate how different thinning options can
be evaluated (Table 10.4; Fig. 10.2). The stand is composed of 6,154 tph, dominated
by Douglas-fir and ponderosa pine. FFE-FVS predicted passive crown fire under
severe weather. Before treatment, canopy base height was 0.6 m, and canopy bulk
lensity was 0.08 kgm-3. The 125 and 250 tph thinning treatments were more effective
than the other treatments because they prevented crown fire initiation by reducing
ladder fuels within the stand. The 125 and 250 tph thinning treatments generated the
highest torching indices, highest canopy base heights, and lowest canopy bulk densi-
ties. The 125 tph treatment produced the lowest basal area mortality.
The lower stand densities plus lower surface fuel loads identified above will
probably be necessary to confer resilience in dry forests in the face of more severe
fire weather. This will tend to reduce the severity of wildfire, and will allow longer
periods of time between thinning treatments needed to maintain low fuels. In some
forests, caution is needed that stand densities not be reduced to a level that will
allow rapid growth of understory vegetation that could increase fire hazard
(e.g., Thompson et al. 2007).
Table 10.4 Effects of thinning and surface fuel treatments on ﬁre hazard on a stand in the
Okanogan-Wenatchee National Forest, as simulated in the Fire and Fuels Extension to the Forest
Thinning treatments (trees ha−1)
Parameters Initial 125 250 500 750
Torching index (km h−1) 0 130 42 19 27
Basal area mortality (%) 7 20 30 21 70
Canopy bulk density (kg m−3) 0.08 0.04 0.05 0.07 0.07
Canopy base height (m) 0.6 12.5 7.0 1.8 1.5
Surface fuelsa (Mg ha−1)
0–7.6 cm 6.6 22.0 26.4 30.8 30.8
7.6–15.2 cm 8.8 13.2 17.6 19.8 17.6
15.2–30.4 cm 8.8 8.8 6.6 6.6 4.4
> 30.4 cm 0 0 0 0 0
Litter 4.4 8.8 8.8 11.0 11.0
Duff 26.0 22.0 19.8 17.6 15.4
Adapted from Johnson et al. (2007)
a FFE-FVS assigned the initial fuel loading for each fuel component and size class
260 D.L. Peterson et al.
10.3.3 Landscape Considerations for Fire and Fuels
Stand-based treatments and evaluations will be more effective when applied in the
context of a strategic plan for large landscapes. Therefore, a major challenge in fire
management is to determine the optimal placement and size of fuel treatments on
the landscape. Fuel treatments are not intended to stop a wildfire, but they can alter fire
Fig. 10.2 Visualizations of thinning for a stand in the Okanogan-Wenatchee National Forest, as
simulated in the Fire and Fuels Extension to the Forest Vegetation Simulator, including Initial
conditions and four post-thinning stand densities (trees ha−1 = tph). (a) Initial conditions, (b)
thinned to 750 tph, (c) thinned to 500 tph, (d) thinned to 250 tph, (e) thinned to 125 tph. See
Table 10.4 for stand and fuel characteristics (Adapted from Johnson et al. (2007))
26110 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
behavior (Finney and Cohen 2003). Fire managers do not have the capacity or
resources to treat all areas that need to be thinned, because of land ownership, conflicting
management objectives, and funding limitations (Finney 2007). Given these con-
straints, decisions about location and size of treatments can be explored with optimiza-
tion models (e.g., Finney 2007), expert knowledge of local landscapes (Peterson and
Johnson 2007), and examination of spatial patterns of forest structure and fuels over
large landscapes over time (Fig. 10.3). In general, placement of treatments is designed
to create landscape patterns that deter wildfire spread and modify fire behavior, while
minimizing area needed for treatment (Finney 2001; Hirsch et al. 2001). Some model-
ing tools have options for determining the spatial arrangement and placement of fuel
treatments. For example, Finney (2007) developed an algorithm to locate the specific
treatment areas that reduce fire growth by the greatest amount for target environmental
conditions. This type of modeling tool is the first step in developing an application that
will help managers to determine the best location to place treatments with the goal of
reducing wildfire behavior across a landscape.
Millions of hectares of public and private land would benefit from thinning
treatments and surface fuel removal to reduce wildfire behavior (U.S. Forest Service
2000), but they are often not treated because of cost, potential (for prescribed burn-
ing) to cause air pollution, lack of safe periods for (prescribed burning) treatment,
and esthetic reasons (Rummer 2008). Cost is related to two forms of treatment, in
situ and extraction. In situ operations are designed to change the structure and
arrangement of fuel loads and involve activities such as prescribed fire, mastication,
or pile-and-burn. Extraction is the removal of fuels and usually costs considerably
Fig. 10.3 Fuel treatment planning can be improved by quantifying stand structural conditions and
fuels across large landscapes over time. Simulation tools can be used to examine the effects, place-
ment, and visual appearance of thinning and fuel treatments throughout stand development. As
stand conditions change from pretreatment (2000) to treatment + regeneration (2015) to regrowth
(2030), subtle changes in landscape pattern and structure ensue (seen in the three landscape
262 D.L. Peterson et al.
more than in situ methods unless the material removed has economic value. The cost
of a project can be calculated from expert opinion, total bid cost, financial records
of total enterprise costs, and economic analysis of fixed and variable costs (Keegan
et al. 2002; Rummer 2008). Regardless of the methods used for treatment and cost
calculation, it may become increasingly difficult for resource managers to treat suf-
ficient area to significantly affect fire spread and behavior in a warmer climate.
Fuel treatments can have unintended consequences on other forest resources.
For example, thinning and surface fuel treatments can provide an avenue for propa-
gation of exotic plant species (Crawford et al. 2001; Griffis et al. 2001). Prescribed
fire can scorch the crowns of live trees, which may increase stress or tree mortality
(Graham et al. 2004). However, the biggest effect of fuel treatments is often on
wildlife habitat (Randall-Parker and Miller 2002), with animal species that
depend on complex forest structure being negatively affected (Pilliod et al. 2006).
For example, a fuelbed structure that prevents crown fire initiation may decrease
habitat for species that depend on large patches of dense multi-story forest (e.g.,
many species of neotropical migrant birds). Alternatively, species that forage in
open forest structure (e.g., ungulates) may benefit from fuel treatments. Accounting
for this interaction among resources will be a challenging consideration in fuel
treatment planning in a warmer climate, because a warmer climate may directly
affect those individual resources as well as the interactions.
The current warming trend in northern latitudes will almost certainly lead to
increased area burned by wildfire in most ecosystems, with associated effects on
ecosystem structure and function. Fuels will be flammable for longer periods of
time. Prolonged droughts and insect attacks may increase fuel loads, leading to
increases in fire hazard and fire severity. Exotic plants could further alter fire
regimes in some ecosystems (Chap. 8), challenging our ability to manage for resil-
ient and sustainable landscapes. A warmer and drier climate will reduce the effec-
tiveness of fuel treatments in some locations. In these cases, using disturbance
events such as wildfire as opportunities to influence species composition for resil-
ience to climate change may be the best adaptation option.
Incorporating potential climate change effects and strategies into management
plans will be a key step for agencies and organizations in adapting to climate change.
Planning for potential impacts of climate change will increase preparedness, allow
for time-efficient response to the effects of climate change, and minimize economic
and ecological costs.
Many resource managers consider the current political and regulatory environ-
ment to be a severe limitation on adaptation to climate change (Joyce et al. 2008;
Littell et al. N.d.). Policies, regulations, and administrative guidelines, though well
intended for various conservation objectives, often fail to incorporate climate
change and therefore focus on static (e.g., historic range of variation) rather than
26310 Managing and Adapting to Changing Fire Regimes in a Warmer Climate
dynamic resource objectives. Lengthy planning, review, and approval processes can
delay timely implementation of management actions (e.g., following a large wild-
fire) that could facilitate adaptation. Some of these constraints can be overcome by
institutionalizing science-management partnerships in order to develop guidelines
for addressing fire issues in a warmer climate. Incorporating climate change explic-
itly into national, regional, and national forest policy would be a major step forward
in implementing climate change in established planning processes. “Climate-smart”
policies and regulations that provide guidance but allow for local forest-level strate-
gies and management actions that increase resilience and reduce vulnerability to
climate change would also promote adaptation. Educational efforts to promote
awareness of climate change will help create a more consistent approach within
land management agencies and encourage support from stakeholders for fire and
fuels management that facilitates adaptation to climate change.
We are optimistic about future opportunities to adapt to climate change with
respect to fire. First, a familiar conceptual framework such as adaptive management
can be used to facilitate fire and fuels management in a warmer climate. Second,
there appears to be a core set of management strategies on which adaptation to
climate change can be based (Table 10.1) (Millar et al. 2007; Joyce et al. 2008;
Littell et al. N.d.). Third, it appears that resource managers with professional exper-
tise on local landscapes can develop viable options for adapting to climate change
if scientists can provide the scientific basis for decision making (Table 10.2). The
scientific basis for managing fuels to enhance resilience already exists (Table 10.3)
but will need to be continually tested for application to large landscapes. Such test-
ing can initially be done in the simulation environment, but judicious and cautious
experimentation by management will likely provide the greatest opportunities for
adaptation and learning.
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