The Impact of Forest Management Practices on Wildfire Severity in

the Sierra Nevada

Mariah Thomas Environmental Policy Thesis

18 May 2015

 

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Table of Contents

Abstract  ..............................................................................................................................................................  5  Introduction  ......................................................................................................................................................  6  Background  .......................................................................................................................................................  7  The  Importance  of  Wildfire  ........................................................................................................................................  7  Fire-­‐Dependent  Species  ................................................................................................................................................  8  

A  History  of  Forest  Management  ................................................................................................................  9  Fire  Suppression  Policies  .............................................................................................................................................  9  Human  Relationships  with  Wildfire  .....................................................................................................................  10  

Consequences  of  Fire  Suppression  .........................................................................................................  10  Increased  Forest  Density  ..........................................................................................................................................  10  Increased  Fuel  Loads  and  Fire  Severity  ..............................................................................................................  11  Impacts  of  High  Severity  Fires  ................................................................................................................................  12  

Forest  Management  Practices  ..................................................................................................................  13  Fuel  Load  Treatments  ................................................................................................................................................  13  Distribution  of  Treatment  Units  ............................................................................................................................  14  

The  Effectiveness  of  Fuel  Treatments  ...................................................................................................  15  Benefits  of  Fuel  Treatments  ....................................................................................................................................  15  Animal  Response  to  Fuel  Treatment  ...................................................................................................................  15  Factors  that  Limit  Success  ........................................................................................................................................  16  

Other  Factors  and  Concerns  .....................................................................................................................  17  Climatic  and  Biological  Factors  ..............................................................................................................................  17  Differences  in  Forest  Management  .......................................................................................................................  18  

Conclusion  ......................................................................................................................................................  19  Appendix  I:  Tables  .......................................................................................................................................  21  References  ......................................................................................................................................................  23  

 

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Abstract  

The Sierra Nevada’s unique ecological composition and rich biodiversity formed under

the influence of routine wildfire. Since Euroamerican settlement of the area in the mid-19th

century, forest management practices were aimed at protecting residents, widespread

development, and valuable natural resources, and therefore sought to suppress wildfire. The

consequences of fire suppression are significant, and have led to changes in the natural fire

cycle and forest structure. High-density forests and shifting climatic factors such as snowpack

depletion and drought have promoted a trend of increased proportions of high-severity wildfire.

In the face of climate change and the complexities of forest health such as animal habitat

requirements, the increasing presence of human development, and pests such as the California

pine beetle, management of Sierra Nevada’s forests is becoming increasingly difficult. Some land

managers have worked to address the problem of dense, fire-vulnerable areas by applying fuel

reduction treatments to the forest, but efforts need to be intensified in order to meet the needs of

forests that are currently unhealthy, fire-vulnerable, and dangerously dense.

 

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Introduction  

California’s Sierra Nevada mountain region possesses diverse and aesthetic landscapes

filled with a myriad of natural resources, inherent recreational value, and important animal

habitats that support a rich biological community. Formed by a unique geological and natural

history, the Sierra Nevada region has distinctive ecological characteristics, including its special

relationship with wildfire. Natural wildfire, under a cyclical pattern of reoccurrence, (Miller et al.

2009) maintains forest health by regularly reducing stand density and encouraging the

establishment of fire-tolerant plant species (Stephens et al. 2012, North et al. 2009). Regular

wildfires that burned at mostly lower to intermediate levels of severity led to well-maintained

densities of understory plants and fuel loads, varied habitats across the landscape, and high levels

of biodiversity (Safford et al. 2012, Stevens et al. 2012).

Sierra Nevada forest management practices that were implemented in the early 20th

century have unintentionally caused changes to the historic forest structure and fire cycles that

present challenges to land managers (Agee and Skinner 2005). The deviation from the natural

fire cycle—which once played a role in maintaining forest health, density, and fire resilience—

has led to concerns regarding an observed upward trend of large wildfires with greater

proportions of high-severity fire in the lower and intermediate elevations of the mountain region

(Lydersen et al. 2014, Miller et al. 2009, Stephens et al. 2010, Miller and Safford 2012, Hanson

and Odion 2014). Sierra Nevada forests were historically less vulnerable to fire than modern

forests because this cycle of frequent wildfire never allowed forest fuel to build up, and the

lengthening periods between wildfires in the last century has influenced the dynamic relationship

between fire frequency and the potential for megafires—large, high-severity fires that cause

extensive post-fire damage like erosion and tree death (Miller et al. 2009, Safford et al. 2012,

 

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Stevens et al. 2012). There is a growing need to investigate the most efficient and successful

management practices to reduce the growing regularity of large blazes. Previous studies have

addressed the overall effectiveness of various forest management methods by assessing

management techniques and the effects of wildfires in treated and untreated forests. This project

will focus on the fire history of the Sierra Nevada and the influence of forest management on

wildfire trends.

Background

The Importance of Wildfire  

The unique ecological treasures of the Sierra Nevada are the products of complex

geological and biological interactions, as well as the presence of regular wildfire. Spanning 25

million acres along the western edge of California, the mountain range’s iconic peaks and

distinct habitats were shaped by the uplifting and weathering of granitic plutons, periodic glacial

carving, and complex hydrological cycles (SNEP 1996, Hill 2006). The Mediterranean is marked

by hot, dry summers and snow accumulation in the high elevation mountain slopes during the

wet winters, a seasonal pattern that primes the forest for frequent blazes during the dry summer

(SNEP 1996, Steel et al. 2015). Historical records indicate that the length of time between fires,

called the fire return interval (FRI), once averaged between ten and twenty years, while FRI

estimates today are decades longer (Stevens et al. 2007, Safford et al. 2012, Steel et al. 2015).

The regular cycle of fire disturbance events molded the landscape, an ecological process that

maintained forest health, density, and vegetative composition (Steel et al. 2015).

Fires are natural disturbance processes that have been vital to the functioning of Sierra

Nevada ecosystems (Steel et al. 2015). The presence of wildfire initiated the formation of diverse

 

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forest types, forming and maintaining a variety of plant communities (Safford et al. 2012).

Despite ranges in habitat location, biological community, and local weather patterns, Sierra

Nevada habitats have shared a common history of low temperature wildfire that mostly burned at

low- to moderate-severities. Historical patterns of high-severity fire, which occurred only in

small patches, formed suitable habitats for a variety of biological organisms, such as early

successional forests. The distribution of fire severity contributed to the amount and type of

available animal and plant habitat in many ways (Collins and Stephens 2010), and rarely

developed into catastrophic, stand-killing fire events because the recent stamp of previous fires

nearby prevented it from spreading far (Schoenherr 1992).

Fire-Dependent Species  

The forests that were seen by the first 19th century settlers were much more open than today,

possessing stands of trees separated by wide expanses of open space and large populations of

old-growth trees and snags—standing dead trees that are vital to the survival of some species

(Larson and Churchill 2012, Safford et al. 2012). These and other habitats that were formed by

wildfire were crucial for the development and continuance of the Sierra Nevada floral and faunal

communities. The forests that formed under this regularly shifting mosaic of wildfire require

regular exposure to wildfire in order to maintain the structure of the biological community

(Stephens et al. 2012, Safford et al. 2015).

A number of plant and animal species are dependent on wildfire’s regular influence on

the area, including old forest obligates and other fire dependent species that are limited to habitat

ranges that experience the right amount and distribution of wildfire (Miller et al. 2009). The

Pacific fisher (Martes pennant pacifica), a member of the weasel family, and the California

 

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spotted owl (Strix occidentalis occidentalis) only reside where old-growth trees grow and snags

occur in the Sierra Nevada (Hansen et al. 2014, Stephens et al. 2014). Lacking a regular fire

regime, these species are threatened with a loss of habitat (Steel et al. 2015). Likewise, the

redwood (Sequoiadendron giganteum) requires the heat from moderate wildfire to open its cones

and released its seeds for distribution (Schoenherr 1992). Regardless of its importance to habitat

heterogeneity and animal populations, the changing dynamics of habitat creation and wildfire

have caused increased rates of dangerously large wildfires (Dolanc et al. 2014; Hansen et al.

2013).

A History of Forest Management

Fire Suppression Policies  

Fire suppression has had long-lasting impacts on the perceptions of land managers and the

public towards forest management. As western civilization has enjoyed economic development

and population growth for the past century, fire suppression tactics sought to protect regional

resources and residents by extinguishing fires immediately after ignition (Running 2006, Miller

et al. 2009, Safford et al. 2012, Safford et al. 2015). Ultimately, fire exclusion policies have been

efficacious at eliminating 97% of fires under 300 acres (Steel et al. 2015) and reducing the

number of annual fires to 6% of what it was in the 1930s; however, this statistic fails to tell the

whole story (Miller et. al, 2009).

Despite the good intentions of this policy decision, its implementation has increased the

chance of catastrophic fires (Miller et. al, 2009) and has been linked to increases in wildfire size

and severity. Long periods without fire allows for fuel, in the form of organic material, to build

up on the forest floor and in the understory (Schmidt et al. 2008, Lydersen et al. 2014). While

 

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firefighting agencies have been successful at extinguishing most wildfires, the unburned and

excessive fuel load makes that task more difficult over time by increasing the likelihood of

explosive and unmanageable megafires (Safford et al. 2012).

Human Relationships with Wildfire  

Human presence is not entirely to blame for changing fire trends; wildfire was a

reoccurring and frequent natural phenomenon when Native Americans settled the region.

Generations of traditional ecological knowledge taught Native American tribes to recognize the

benefits of wildfire. They learned to use it as a land management tool, allowing naturally ignited

fires to burn and regularly starting fires on purpose (Schoenherr 1992, Anderson and Moratto

1996). This practice was utilized for centuries to improve understory growth and promote

biodiversity (Steel et al. 2015), and their active resource management played a role in shaping

the ecological structure (Anderson and Moratto 1996). After Euroamerican settlement, the way

people perceived wildfire grew less accepting as cities and industries were built, fueled by

California’s abundant resources, and wildfire began to threaten profit, safety, and valuable assets

like timber, gold, and land for ranching (Steel et al. 2015).

Consequences of Fire Suppression

Increased Forest Density  

The absence of wildfire has primed Sierra Nevada forests with higher-than-average levels of

fuel and caused changes in vegetation structure, including a more homogenous species

composition and changes in tree density (Scholl and Taylor 2010, Miller and Safford 2012).

 

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Collectively, fire suppression and old-growth tree harvests led to larger populations of small-

diameter trees, ultimately increasing overall stem density in yellow pine and mixed conifer

forests, despite the drop in numbers of large trees (Dolanc et al. 2014, Gruell 2001, Safford et al.

2012).

Fire-intolerant and shade-loving species, such as white fir, incense cedar, and canyon live

oak, which were historically prevented from reaching maturity and high population density

(Safford et al. 2012, Stephens et al. 2012), have experienced the most significant increases in

numbers as the canopy closed in (Oliver and Dolph 1992, Fites-Kaufman et al. 2007, Dolanc et

al. 2014). The denser, shadier forests created by the absence of wildfire are suitable habitats for

fire-intolerant species to thrive. They can contribute to a loss in biodiversity by outcompeting

species less suited to the shade and their increased population density play a role in fueling high-

severity wildfire. Having no adaptations to deal with wildfire, they experience high mortality

rates during high-severity fire events (Safford et al. 2012).

Increased Fuel Loads and Fire Severity  

Wildfire only burns as long as it has available plant biomass to consume (Steel et al. 2015); it

can be compared to an herbivore in that it reduces its own fuel source through consumption

(Bond and Keeley 2005). Under natural conditions, fires maintain forest health by preventing

overgrowth and buildup of fuel (Table 1), thus improving fire-resistance (Stephens et al. 2014).

In California, slow decomposition rates and low humidity levels compound the problem of fuel

buildup (Running 2006). Higher volumes of dry organic material on forest floors contribute to

fire severity and frequency. The rate of accumulation of dead and woody material in the forest

floor layer is a major factor in fire duration and strength once a fire occurs (Stephens et al. 2014).

 

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Since 1984, fire size (Dolanc et al. 2014, Thompson et al. 2010) and proportion of high-

severity fire have risen in the lower and intermediate elevations; from historical averages of 5-

15% high-severity fire to recent wildfires that burned at rates up to 50% high severity (Miller and

Safford 2012, Collins and Stephens 2010). This rise in high-severity fire is most common for

fires reaching areas of at least 400 hectares; an approximate 95% of area burned is caused by

only 5% of annual fires (Westerling et al. 2006, Miller and Safford 2012), meaning that the

largest fires have also been the most destructive. Perhaps the most well known example of a

megafire is the Rim Fire, which burned 257,000 acres and is recorded as the largest wildfire in

Sierra Nevada history (Thompson et al. 2010, Lydersen et al. 2014; Collins and Stephens 2007).

Impacts of High Severity Fires  

Large fires like the Rim Fire are expensive to fight and mitigate, and can cause severely

negative impacts to extractive industry interests, communities, and a range of natural resources

(Westerling 2006, Thompson et al. 2010). The close proximity of trees in dense forests leaves

them vulnerable to crown fires because plant overgrowth serves as a ladder for fire to reach the

canopy, where it easily spreads. The severe damage to trees in canopy fires increases stand

mortality rates and causes forest fragmentation, breaking up the forest ecosystem and threatening

sensitive wildlife habitat due to the death of large canopy tree stands (Miller et al. 2009,

Lydersen et al. 2014).

Not only are the biological aspects of forests altered by high-severity fires, so are abiotic

ones like erosion and carbon emission rates. Once stripped of its protective root framework, soil

becomes exposed to the elements and erosion rates spike after large fires. Mudslides and runoff

pollute nearby waterways with deposits of sedimentation and contaminants such as heavy metal

 

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particles and nutrients (Miller et al. 2009, Thompson et al. 2010). The carbon released during the

wildfire and subsequent decomposition combines with the amount of carbon that would have

been stored in the biomass of living trees and compounds the overall carbon footprint of high-

severity wildfires (Miller et al. 2009).

Today, increased human presence in areas that historically experienced frequent low-severity

fires makes humans and communities vulnerable to high-severity wildfires. Areas with

documented increases in wildfire severity are those that have utilized suppression tactics to

protect valuable natural resources and growing human populations (Miller et al. 2009),

complicating management objectives and implementation. The rising rates of wildfire damages

to homes, fire-related human death, and cost to the government are all negative consequences of

increased wildfire severity (Safford et al. 2012). Wildfire events can destroy buildings and

natural resources; this loss of capital combined with expensive firefighting efforts add up to

annual expenditures often rising above $1 billion (Westerling 2006).

Forest Management Practices

Fuel Load Treatments  

Developing management policies to deal with more frequent megafires is a difficult task

due to the complex relationship between human development in rural areas and complex

ecosystem functions (Ritchie et al. 2006, Dolanc et al. 2014). A return to a natural fire cycle like

that of past centuries would be difficult in many parts of the Sierra Nevada, but there are a

number of fire surrogate methods that can be employed to treat forest fuel loads that may reduce

wildfire risk and severity (Table 2; Stephens et al. 2012, Kent et al. 2015). Goals of forest fuel

load treatments are aimed at recreating forest conditions that mimic those of historic and healthy

 

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forests. Removing understory overgrowth and small-diameter trees to reduce stand density may

decrease the chance of large, high-severity fires like the Rim Fire (Stephens et al. 2012).

Treatment methods vary among landowners, the method chosen being dependent on the

landowner’s priorities, goals, and budget (Table 3; Agee and Skinner 2005, Kocher 2012,

Stephens et al. 2012, Lydersen et al. 2014). Prescribed burning is the most common practice and

is widely considered to be the most effective form of treatment, particularly in conjunction with

other treatments, which include mechanical thinning, or tree thinning, hand thinning, and

mulching (Agee and Skinner 2005, Safford et al. 2012, Stephens et al. 2012).

Distribution of Treatment Units   The type of forest treatment needs to be considered, but equally important to treatment

effectiveness is the arrangement of treatment units. Forest management has been limited in the

past to stand-scale treatments (Schmidt et al. 2008) that focus on removing flammable materials

and reducing the forest stand density in relatively small areas (Stephens et al. 2014). In contrast,

landscape-scale projects strategically arrange treatment units throughout a much larger area,

using existing barriers such as rivers and roads in ways that make megafires easier to contain as

well as reduce the total area burned (Schmidt et al. 2008, Collins et al. 2010, Thompson et al.

2010). In an effort to reduce large and devastating fires, carefully located treatment units provide

the fire with opportunities to intersect forest treatment areas at a number of points by focusing on

fire behavior as a whole (Schmidt et al. 2008, Collins et al. 2013). In simulated models of

wildfire in both pretreated and post-treated land, landscape-scale fuel treatments have been found

to be more effective at reducing fire size and burn probabilities than stand-scale treatments of the

same type (Moghaddas et al. 2010).

 

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The Effectiveness of Fuel Treatments

Benefits of Fuel Treatments  

Fuel treatment effectiveness is frequently linked to reduced fire severity and tree

mortality rates by assessing wildfire effects and comparing simulated fire models and surveys of

areas burned by wildfire on treated and untreated lands. Scientists and land managers can use the

results as a tool to determine whether a fuel treatment would meet management goals for a

certain locality (Murphy 2007, Safford et al. 2012, Lydersen et al. 2014). Fuel treatments have

been found to have a range of benefits on the landscape and fire resilience, reducing moderate-

and high-severity fire severity, and decreasing the effects on the forest canopy. In contrast,

untreated areas burn at higher temperatures with crown level flames (Murphy 2007, Kent et al.

2015).

Animal Response to Fuel Treatment  

The overall impacts of fuel treatments to animal habitats are complex, but observed

responses of biological communities to treatments indicate that the benefits outweigh the

disadvantages by reducing tree mortality (Stephens et al. 2014). Avian communities, including

the California spotted owl (Stephens et al. 2014), as well as two of its favorite small mammal

prey species—the dusky-footed woodrat (Neotoma fuscipes) and the northern flying squirrel

(Glaucomys sabrinus) (Innes, et al. 2007, Smith et al. 2011)—had minimal responses to fuel

treatment and maintained population sizes (Carey and Wilson 2001). Even though positive

responses to treatment such as increased diversity have been noted, treatment is unable to fully

 

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mimic wildfire-created forest conditions at a landscape level (North et al. 2009). More

assessments are needed to fully assess population responses throughout the biological

community (Stephens et al. 2014).

Factors that Limit Success  

Though treatments are often successful at reducing fire risk and effects, there are factors

unrelated to fuel treatment status that influence fire behavior, most notable are unfavorable

weather conditions such as high winds, low humidity, and hot temperatures (Lydersen et al.

2014). The Rim Fire, which occurred partially in forests with restored fire regimes, experienced

fire patterns indicating even treated stands can be overwhelmed by extreme weather conditions

(Finney et al. 2003, Lydersen et al. 2014). Old growth forests that were affected during the Rim

Fire burned at 23-40% high severity, despite the restored fire regime (Collins and Stephens 2007,

Thompson et al. 2010, Lydersen et al. 2014). On extreme weather days a fire can continue

burning at high-severity for distances reaching 25 m and more until the open canopy reduces

flame height, as it moves from untreated land to adjacent treated areas (Murphy 2007, Lydersen

et al. 2014). To reduce fires under extreme conditions, buffers at the interface between treated

and untreated forest patches as wide as 500 m have been recommended (Safford et al. 2009).

Fuel treatment longevity is another concern for land managers, usually requiring subsequent

fire cycles to maintain the restored conditions (Safford et al. 2014). In Yosemite National Park,

treatments have an estimated lifespan of nine years; forests burn once the fuel level has

accumulated sufficiently and weather conditions are suitable (Safford et al. 2014). Relative

lifespans of treatments may be considered when land managers select fuel treatment types

(Safford et al. 2014, Agee and Skinner 2005). The high price of fuel treatments and the range of

 

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stakeholder interests that must be considered in the decision making process complicates

treatment and management efforts (Stephens et al. 2014).

Other Factors and Concerns

Climatic and Biological Factors  

Fire suppression is one factor behind changes in wildfire and forest density trends, but other

factors known to influence wildfire should be considered. Fire behavior is influenced on a local

scale by topography, (Miller et al. 2009, Miller and Safford 2012), elevation, and regional shifts

in precipitation (Lydersen et al. 2014). Factors such as the statewide drought, rising annual

temperatures, and earlier snowmelt have all impacted wildfire trends (Westerling et al. 2006,

Miller et al. 2009). Warmer winter conditions are a major concern; precipitation falls as rain

rather than snow and melts much quicker—at least two weeks earlier today than in the early 18th

century (Dolanc et al. 2014).

The dwindling snowpack levels and quicker rates of snowmelt create less water availability

in the summer. As the main source of annual stream flow and a factor in summer forest

humidity, predictions of continued decreases to snowpack implicate future challenges for both

water supply and the wildfire conditions (Running 2006, Westerling et al. 2006, Kapnick and

Hall 2010), especially during summer when downstream water users and habitats rely most on

the runoff (Dolanc et al. 2014, Hansen et al. 2014). Years with relatively long fire seasons and

early snowmelts have more fires on average than those with average fire seasons due to the lack

of water and the flammability of organic fuels (Running 2006, Westerling et al. 2006, Miller et

al. 2009). Already difficult to predict and manage, longer fire seasons present new challenges to

land managers and firefighting agencies (Westerling et al. 2006).

 

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Another factor that may influence fire cycles is the infestation of the northern bark beetle, a

native species to the Sierra Nevada that has spread to unmanageable levels due to water stress

(Hicke et al. 2012). Their lifecycle is linked to climate, so reductions in wildfire frequency,

rising temperatures, and fewer wildfires have increased their ability to spread (Dolanc et al.

2014). Bark beetles can kill large, mature trees that are stressed by drought-like conditions, and

therefore weakened in their immune responses (Dolanc et al. 2014). The millions of trees that

bark beetles have killed provide additional dry organic fuel to burn and may influence fire

behavior and severity, though impact is largely dependent on the length of time since stand

infestation (Hicke et al. 2012).

Differences in Forest Management  

Differences in fire suppression policies provide opportunities to compare management

techniques, including effects of regularly occurring wildfire. The United States Forest Service

(USFS) lands have more than double the proportion of high-severity fire on National Park

Service (NPS) lands, largely due to management differences. The USFS most often uses

immediate suppression tactics in early stages of fire development (Miller and Safford 2012),

while Yosemite National Park, managed by the NPS, has allowed wildfires to burn regularly and

naturally under moderate weather conditions since the 1960s. As a result, the fire regime

Yosemite is similar to historical estimates and regularly reduces stand density naturally (van

Wagtendonk 2007, Miller and Safford 2012, Collins and Stephens 2007). Fires that have

occurred on land that has burned regularly in the last century are generally smaller and less

severe than those that occur on land that has undergone intense fire suppression, but the

abnormally high percentage of high-severity fire in the Rim Fire reveals the overall complexity

 

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of wildfire severity, and its relationship to fire suppression and fuels treatments (Miller and

Safford 201, Lydersen et al. 2014).

Conclusion     The  intervention  of  humans  in  the  natural  fire  cycle  has  changed  the  frequency  of  

the  fire  regime  from  historical  rates.  Rather than burning regularly at low- to moderate-

severity, fires today have become less frequent, larger, and have burned at greater proportions of

high-severity fire. This places human residents, local infrastructure, and animal habitat at risk of

being destroyed by large and unmanageable fires like the Rim Fire.  Some forest management is

aimed towards reducing forest fuels, through fuel treatment, and has the goal of reducing the

amount of fuel available for fires to consume. Forest conditions are in desperate need of

restoration and reduced densities, but landowner efforts are far from adequate. There are

approximately 6-9 million acres of USFS lands alone that are in need of fuel treatments, but the

rate of restoration is only half of what is needed to reduce fire risk (Thompson et al. 2010).

No single solution exists for reducing fuels and improving the forest conditions in the Sierra

Nevada, but a comprehensive reassessment of current forest management practices needs to be

made. In the face of climate change, the current drought and other complex factors such as the

bark beetle infestation that impact fire season in addition to forest management practices,

treatment and restoration efforts need to be directed towards an uncertain future. California’s fire

season is unlikely to improve, shorten, or become less costly, so forest health projects need to be

focused on impacts that will benefit fire resilience, animal habitat, and human interests as much

as possible.

 

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Appendix I: Tables

Table 1: Definitions of fuel types, where they occur, and their effect on wildfire behavior (information from: Stephens et al. 2012, Safford et al. 2012, Agee and Skinner 2005). Fuel Type Definition Effect on Fire Behavior Ground Lowest layer, includes all organic

material on forest floor Low to moderate

Surface Larger volume and biomass than ground fuel; located just above forest floor, includes fallen trees, small plants

Most dangerous, the focus of treatment efforts; can provide passage for fire to reach crown

Ladder Understory vegetation, bushes and small trees

Provides a “ladder” for fire to reach the canopy

Crown Canopy tree biomass Fires reaching this level are difficult to control; burning increases mortality rates of mature trees

   Table  2:  Fuels treatment types, definitions, advantages, and disadvantages. Prescribed burning is the most effective (information from Stephens et al. 2014).    Type  of  Treatment  

Definition   Fuels  Treated  

Advantages   Disadvantages  

Prescribed  Burning  

Intentional  ignition  or  allowance  of  fire  to  burn  naturally;  broadcast  or  pile  burns  

Surface;  Understory  

Closely  mimics  natural  fire  regime;  minimal  damage  to  mature  trees  

Best  if  used  in  combination  with  others;  Lower  social  acceptance;  Leaves  soil  exposed  

Mechanical  Treatment  

Uses  heavy  equipment  to  remove  selected  trees;  whole-­‐tree  harvesting    

Canopy;  Ladder  

Very  precise,  can  focus  on  specific  sizes;  cost-­‐effective;  opens  up  tree  canopy  

Best  in  areas  near  processing  facilities,  before  prescribed  burn;  excess  woody  debris  on  forest  floor;  may  damage  nearby  trees  

Combined   Mechanical  thinning  followed  by  prescribed  burning  

All  fuels   Most  effective  form  of  treatment;  opens  canopy  and  removes  floor  debris  

Expensive  and  difficult  to  implement  on  large  scales  

 

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Mulching   Chipping  removed  biomass  and  spreading  it  across  forest  floor  

Ladder;  Understory    

Cost-­‐effective   Increases  surface  fuels  and  may  contribute  to  wildfire  severity  

Table 3: Ownership of productive forestland in the Sierra Nevada, by percent of forest land owned and percent of public forest land owned by each landowner category (table from Kocher 2012).

Ownership Acres Percent of Forest Land Owned

Percent of public forest land owned

USFS 6,322,189 59% 84% NPS 962,589 9% 13% BLM 149,187 1% 2%

Other Public 102,780 1% 1% Private/NGO 3,143,291 29% ---- Grand Total 10,680,037

 

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