United States

Department of

Agriculture

Forest 

Service

July 2017

Fire and Fuels Report

Craggy Vegetation Management Project

Scott River Ranger District, Klamath National Forest

Siskiyou County, CA

For Information Contact: Clint Isbell

1711 South Main Street, Yreka CA 96097

530 841-4510

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Table of Contents

Fire and Fuels Resource Report...................................................................................................1

Introduction............................................................................................................................. 1

Policy, Laws, and Direction................................................................................................ 1

Methodology........................................................................................................................... 2

Analysis Indicators.................................................................................................................. 3

Measures: ........................................................................................................................ 3

Flame Length Potential....................................................................................................... 4

Fire Type (Crown Fire Potential)........................................................................................ 4

Fire Behavior Potential on Dominant Vegetation Type and Size Class............................. 5

Spatial and Temporal Bounding of Analysis Area ................................................................. 5

Affected Environment............................................................................................................. 7

Affected Environment for the Project Area ........................................................................ 7

Fire Hazard Measured by Flame Length .......................................................................... 10

Fire Type (Surface, Passive Crown or Active Crown Fire).............................................. 10

Fire Regime Impacts to Vegetation .................................................................................. 10

Affected Environment for the Wildland Urban Interface ................................................. 11

Environmental Consequences............................................................................................... 12

Alternative 1...................................................................................................................... 12

Direct and Indirect Effects in the Project Area and Wildland Urban Interface ............ 12

Cumulative Effects........................................................................................................ 12

Alternative 2...................................................................................................................... 13

Direct and Indirect Effects in the Project Area............................................................. 13

Direct and Indirect Effects in the Wildland Urban Interface Area ............................... 14

Cumulative Effects........................................................................................................ 16

Alternative 3...................................................................................................................... 17

Direct and Indirect Effects in the Project Area............................................................. 17

Direct and Indirect Effects in the Wildland Urban Interface Area ............................... 18

Cumulative Effects........................................................................................................ 19

Comparison of Alternatives.................................................................................................. 19

Comparison of Alternatives for the Project Area ............................................................. 19

Comparison of Alternatives for the Wildland Urban Interface ........................................ 21

Compliance with law, regulation, policy, and the Forest Plan ............................................. 22

Literature Cited..........................................................................................................................23

Appendix A – Climate and Climate Change .............................................................................26
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Fire and Fuels under Climate Change............................................................................... 26

Appendix B - Fire Regime and Historical Reference Conditions (Condition Class)................27

Appendix C – Fuels and Fuel Modeling....................................................................................29

Fuels.................................................................................................................................. 29

Fire Risk............................................................................................................................ 30

Appendix D – Wildland Urban Interface Zones within Craggy Project Area...........................31

List of Tables

Table 1: Modeling Inputs Based on Weather Conditions under 90th Percentile Conditions*.......................3

Table 2: Flame Length Potential and Fireline Intensity used to Describe Analysis of Measurement 

Indicators...............................................................................................................................................4

Table 3: Flame Length Potential for the Project Area for Alternative 1 in Acres and Percent of the Project 

Area.....................................................................................................................................................10

Table 4: Fire Type Potential for the Project Area for Alternative 1 in Acres and Percent of the Project 

Area.....................................................................................................................................................10

Table 6: Fire Behavior Potential on Size Class for the Project Area for Alternative 1 in Acres................11

Table 7: Forest and Private Lands by Wildland Urban Interface Zone within the Project Area. ...............11

Table 8: Current Flame Length Potential within the Wildland Urban Interface Zone................................12

Table 9: Flame Length Potential for the Project Area for Alternative 2 in Acres and Percent of the Project 

Area.....................................................................................................................................................13

Table 10: Fire Type Potential for the Project Area for Alternative 2 in Acres and Percent of the Project 

Area.....................................................................................................................................................13

Table 11: Fire Behavior Potential on Dominant Vegetation Type for the Project Area for Alternative 2, in 

Acres...................................................................................................................................................13

Table 12: Fire Behavior Potential on Size Class for the Project Area for Alternative 2 in Acres..............14

Table 13: Short-term Flame Length Potential within the Wildland Urban Interface under Alternative 2..15

Table 14: Mid-term Flame Length Potential within the Wildland Urban Interface under Alternative 2....15

Table 15: Flame Length Potential for the Project Area for Alternative 3 in Acres and Percent of the 

Project Area ........................................................................................................................................17

Table 16: Fire Type Potential for the Project Area for Alternative 3 in Acres and Percent of the Project 

Area.....................................................................................................................................................17

Table 17: Fire Behavior Potential on Dominant Vegetation Type for the Project Area for Alternative 3, in 

Acres...................................................................................................................................................17

Table 18: Fire Behavior Potential on Size Class for the Project Area for Alternative 3 in Acres..............18

Table 19: Short-term Flame Length Potential within the Wildland Urban Interface under Alternative 3..18

Table 20: Mid-term Flame Length Potential within the Wildland Urban Interface under Alternative 3....19

Table 21: Flame Length Potential (short-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives.........................................................................................................................................19

Table 22: Fire Type Potential (short-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives.........................................................................................................................................19

Table 23: Flame Length Potential (mid-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives.........................................................................................................................................19

Table 24: Fire Type Potential (mid-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives.........................................................................................................................................20

Table 25: Fire Behavior Potential (flame length) on Dominant Vegetation Types in Acres, Comparing 

Short-term Effects for Alternatives.....................................................................................................20

Table 26: Fire Behavior Potential on Vegetation Size Class for Current Condition as Displayed for 

Alternative 1 Compared to Action Alternatives in the Short Term ....................................................21
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Table 27: Flame Length Potential (short-term) in the Wildland Urban Interface for Alternative 1 

Compared to Action Alternatives .......................................................................................................21

Table 28: Flame Length Potential (mid-term) in the Wildland Urban Interface for Alternative 1 Compared 

to Action Alternatives.........................................................................................................................22

Table B-1: Description of Historic Natural Fire Regimes..........................................................................27

List of Figures

Figure 1: Wildland Urban Interface Zones...................................................................................................6

Figure 2: Areas Within the Project Area that have Burned Prior to and after 1955 .....................................9

Figure 3: Mastication of Brush from the Yreka Project in 2002. This Unit is proposed for Maintenance 

and Re-entry for the Craggy Project and Serves as part of a Key Ridge System for the Fuels Strategy 

and is within the Wildland Urban Interface........................................................................................16

Figure B-1: Historical Reference Vonditions (Condition Class) Based Fire Return Interval Departure....28

Figure D-1: Wildland Urban Interface Zones within Craggy Project Area ................................................31

Fire and Fuels Craggy Vegetation Management Project

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Fire and Fuels Resource Report

Introduction

This report discusses the historic role of fire in the Craggy Vegetation Management Project 

(Craggy Project) area and how current conditions reflect a departure from historic fire return 

intervals. The report then discloses the predicted effects of the proposed action and any action 

alternatives and compares the effects to those of an alternative where no action will occur 

(Alternative 1). The report also discusses current conditions with regard to the wildland urban 

interface and the effects of the alternatives within this area.

The need for action in the project area evolved primarily from changes in fire regimes over the 

last century. Historically, low- to mixed-severity fires in the area played a significant role in 

creating a high spatial complexity of vegetation, including openings of different sizes, forested 

stands that were generally more open and late-successional, and fire resilient forests. Fire 

suppression, along with other past management activities in the project area, resulted in 

uncharacteristically dense vegetation (see the Silviculture Resource Report, available on the 

project website: http://www.fs.usda.gov/project/?project=31770 and high fuel loading, a decline 

in wildlife forage and habitat diversity, and an elevated risk of high-severity, stand-replacing 

wildfires. Since the 1955 Haystack Fire, which burned approximately 70 percent of the project 

area, only about 3,100 acres have burned. Presently, 80 percent or approximately 23,000 acres 

depart, moderately to severely, from historic fire return intervals.

Current concerns focus on high fire hazard (as defined by fuel loading and vegetation densities) 

and high fire risk (as defined by fire start occurrence) over time. Fire risk and associated fire 

hazard have led to concerns over fire behavior in and adjacent to private property and fire effects 

to resource values on National Forest lands (e.g. wildlife habitat, soil stability, human uses, 

hydrology, air quality). In addition, smoke from large fires that does not disperse has the 

potential to negatively impact the project area which has a high level of human use (see the Air 

Quality Resource Report, available on the project website).

The purpose of this project was generated from the Klamath National Forest Land and Resource 

Management Plan (Forest Plan) (USDA 1995, as amended); the Humbug Landscape Analysis 

and Design (USDA 1993); and the Yreka Area Fire Safe Council’s Community Wildfire 

Protection Plan (Yreka Fire Safe Council 2013) with the objectives of reducing the wildfire 

threat to communities, reducing stand density to promote forest health, enhancing early seral 

foraging and winter range habitat, maintaining and improving habitat for sensitive plants, and 

limiting or reducing sediment discharge into streams. Treatments proposed in the project are 

aimed at reducing the threat of wildfire adjacent to private lands and communities as well as 

across a larger landscape level. One of the major goals of this project is to meet the standards of 

the wildland urban interface zones (defined later in this report).

Policy, Laws, and Direction

The following current laws, policy and direction related to fire and fuels apply to the Craggy 

Vegetation Management Project (Craggy Project):

Klamath National Forest Land and Resource Management Plan (Forest Plan);

Forest Service Manual 5100; and
Fire and Fuels Craggy Vegetation Management Project

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Forest Service Manual 2000.

The Forest Plan provides two types of direction related to fuel management: Forest-wide 

direction (pages 4-54 and 4-55) and management area direction. Management area direction 

related to fuel management for the management areas that occur in the project area is found on 

pages 4-89, 4-94, 4-114, 4-116, 4-127, and 4-132. The Forest-wide direction states that fuels 

analysis should address the accumulation of fuels over time, including fuels generated from 

management activities (standard and guideline 22-16, page 4-55) and describe the hazard, risk 

and consequences of a wildfire (standard and guideline 22-19, page 4-55).

In the 2001 National Fire Plan (USDA USDI 2001), the Secretaries of Agriculture and Interior

first directed federal agencies to develop treatments for building more fire resilient communities 

within the wildland urban interface. Since then, several other forms of national direction, such as 

the 10 Year Comprehensive Strategy (USDA USDI 2002) and a cohesive fuels treatment 

strategy (USDA USDI 2006), and the Flame Act of 2009, resulted in the cohesive strategy that

identified at-risk communities as a key problem for fire management.

The Regional Forester of the Pacific Southwest region (Region 5) directed “that the one-hundred 

foot defensible space minimum be included in each Forest’s prioritization of current and out-year 

integrated vegetation management and hazardous fuel reduction program of work and projects”

(RF letter (date)). In California, local and state laws also apply to private landowners and their 

responsibility for fuels treatments and fire prevention on their own land. The State of California 

Public Resources Code 4291, for example, requires landowners to “maintain defensible space of 

100 feet from each side and from the front and rear of [any] structure...in a condition so that a 

wildfire burning under average weather conditions would be unlikely to ignite the structure.”

The Pacific Southwest Regional Forester provided the following direction to Forests: “Where 

consistent with existing Forest Land and Resource Management Plan direction, Forest 

Supervisors will provide for a one-hundred foot defensible space minimum for all structures on 

administrative sites, structures authorized by permit, and for developments adjacent to NFS

[National Forest System] lands. Where needed to carry out this direction, applicable revisions to 

Forest Plans will be made during scheduled Forest Plan amendments, updates or revisions.”

Methodology

Fire behavior modeling was conducted using FlamMap. FlamMap is a fire behavior mapping and 

analysis program that computes fire behavior characteristics over a landscape of constant inputs 

of weather and fuel moisture conditions (Finney 2006). Outputs consist of fire type or crown fire 

potential (Scott and Reinhardt 2001) and flame length potential (Finney 1998). In addition, all 

fire model runs were calculated using LANDFIRE, which uses a vegetation layer to obtain fuel 

models. In addition to fuel models, LANDFIRE is comprised of elevation, aspect, slope, canopy 

cover, stand height, canopy bulk density, and canopy base height to predict fire behavior 

potential. The dominant vegetation type from the EVEG geographic information system layer 

was used for this analysis. The FlamMap model assumes uniform canopy characteristics and 

makes independent fire behavior calculations for each raster landscape (a 90 meter by 90 meter

cell). As a result of these assumptions, the model frequently under-predicts active crown fires 

(Fule et al. 2001; Scott and Reinhardt 2001; Cruz et al. 2003; and Stratton 2004).Weather and 

fuel moisture conditions were calculated by a climatology program (Fire Family Plus) that 

collects historical weather data for analysis. Historical weather data was obtained from remote 
Fire and Fuels Craggy Vegetation Management Project

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automated weather stations at Oak Knoll and Collins Baldy. Ninetieth percentile weather (very 

dry) conditions were put into FlamMap for analysis of fire behavior potential.

Fire behavior modeling uses input variables to calculate fire behavior. The three primary 

variables affecting fire behavior are fuels, weather and topography. Because fuels are the 

primary variable that management activity can influence, they were the main variable used in 

this analysis of fire hazard. Potentially combustible fuels range in type from standing live trees 

and brush (woody fuels) to downed woody debris that ranges from less than a quarter inch in 

diameter (known as 1-hour fuels) to more than three inches in diameter (1000-hour fuels). Fuel 

moisture content and wind speed were based on 90th percentile weather conditions (Table 1).

Table 1: Modeling Inputs Based on Weather Conditions under 90th Percentile Conditions*

Parameter 90th Percentile Weather Output

Woody Fuel Moisture 66

Herbaceous Fuel Moisture 30

1000-Hour Fuel Moisture 7

100-Hour Fuel Moisture 5

10-Hour Fuel Moisture 4

1-Hour Fuel Moisture 3

Wind Speed 7

*90th percentile weather conditions were based on the energy release 

component. The term means ‘very dry’.

Analysis Indicators

Analysis indicators, as measured using information provided in the methodology section, are 

used to compare effects of alternatives. The analysis indicators and measures are described in 

this section.

Analysis Indicator: Fire hazard for the project area and within the wildland urban interface.

A major concern within the project boundary is the current fire hazard, defined by existing fuel 

loading and vegetation densities. Hazard is a source of danger. Wildland fire danger can be 

characterized by how a wildfire will burn or its likely fire behavior. A high fire risk (fire-start 

occurrence over time) and associated fire hazard in the project area have led to concerns over fire 

behavior and fire effects to resource values on Forest lands (e.g. wildlife and late-successional 

habitat, soil stability, hydrology, air quality, and others).

Measures:

• Fire hazard:

 Flame length potential – this was used in analysis for three different aspects: flame 

length within the project area, flame length within the project area by vegetation 
Fire and Fuels Craggy Vegetation Management Project

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categories, and flame length within the wildland urban interface. Flame length is a 

visual and measurement indicator of surface fire intensity. Flame length is defined as 

the distance along the slant of the flame from the midpoint of its base to its tip.

 Fire type (crown-fire potential) - this is an indicator on whether a fire is likely to stay 

on the surface or move through the crowns given a set of stand and burning 

conditions; this was used in analysis for the project area as a whole.

• Fire behavior potential: uses flame lengths and their potential effects to dominant 

vegetation types and sizes of trees under specified modeling conditions (acres of various 

flame lengths within vegetation types and sizes). This is a measurement indicator of 

effective acres treated, determined by flame lengths.

Flame Length Potential

Flame length is an indicator of how hot or severe a fire can become (i.e. a measure of heat 

output) and as a proxy for ease of fire suppression) used to model and predict fire behavior. 

Flame lengths are described in the Fire Management Plan and Appendix B of the Fireline 

Handbook (National Wildland Fire Coordinating Group 2006). This measure provides a means 

for assessing the potential for fires becoming difficult to suppress or contain, the potential to 

threaten communities at risk (i.e. wildland urban interface), and the potential to threaten resource 

values (e.g. wildlife habitat, soil stability, human uses, hydrology, air quality).

Table 2: Flame Length Potential and Fireline Intensity used to Describe Analysis of Measurement Indicators

Flame Length 

(feet)

Fireline Intensity 

(British Thermal 

Units per foot per 

second)

Description

Zero feet 0 Very Low – Non-flammable areas such as rock outcropping, 

water, etc.

Less than 4 feet 0 - 100 Low – Persons using hand tools can generally attack fires at 

the head or flanks of the fire.

4-8 feet 100 - 500

Moderate – Fires are too intense for direct attack on the head 

of the fire by persons using hand tools. Equipment such as 

dozers, engines and retardant aircraft can be effective.

8-11 feet 500 - 1,000

High – Fires may present serious control problems such as 

torching, crowning, and spotting. Control efforts at the head 

of the fire will probably be ineffective.

Greater than 11

feet Greater than 1,000 Very High – Fires present serious control problems and 

control efforts are typically ineffective.

Fire Type (Crown Fire Potential)

Fire type potential is a measure of fire severity, of whether a fire is likely to stay on the surface 

or move through tree crowns given a set of vegetation and burning conditions. This measure is 

useful for analyzing the risk of losing a forested overstory to wildfire, or how resilient the forest 

overstory is to wildfire. Extensive crown fires can especially be an issue in vegetation types that 

are not adapted to respond to high intensity crown fires. Canopy characteristics (e.g. canopy base 
Fire and Fuels Craggy Vegetation Management Project

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height, canopy bulk density, stand height, and foliar moisture content), ladder fuels, and fuel 

loading are all factors that determine fire type.

Crown fire potential is defined by the following categories:

Surface fire – The fire remains on the forest floor. The combination of surface fire intensity and 

ladder fuels is not sufficient to move a fire into the crowns under the defined burning conditions.

Passive crown fire – Individual tree or group torching occurs. The combination of surface fire 

intensity and ladder fuels allows for movement into the crowns under the defined burning 

conditions, but canopy bulk density is too low for fire to spread through the crowns under the 

projected wind speeds.

Active crown fire – The combination of surface fire intensity, ladder fuels and canopy bulk 

density allows fire to move into, and spread through, the crowns under the defined burning 

conditions.

Fire Behavior Potential on Dominant Vegetation Type and Size Class

A major concern within the project area is fire effects potential to vegetation. This measurement 

indicator displays flame length potential on dominant vegetation types and size classes. The 

definitions of flame lengths and fireline intensity can be used to describe potential fire effects to 

vegetation categories and size classes for analysis.

Spatial and Temporal Bounding of Analysis Area

There are two spatial bounds for this analysis. The first will be the project boundary and the 

second will be the area within the wildland urban interface that is associated with the Craggy 

Project (see Appendix D of this report for a map of these analysis area delineations). The effects 

of alternatives on all analysis indicators will be analyzed for the Craggy project area. The effects 

of treatments on fire hazards as measured by flame lengths (a surrogate for fire intensity) for 

wildland urban interface areas will be disclosed.

The wildland urban interface is divided into three concentric zones:

Home Ignition Zone (Zone 1): This is a 100-foot zone around structures as identified by State 

of California Public Resource Code 4291. The goal of this zone is to have no crown fire and for 

flame lengths to be less than two feet, and “Fuels shall be maintained in a condition so that a 

wildfire burning under average weather conditions would be unlikely to ignite the structure” on 

100 percent of the land base (State of California Public Resource Code 4291). Very little Federal 

System lands occur within 100 feet of structures, therefore the Craggy Project focuses primarily 

on the defense and threat zones, including areas adjacent to private land and the home ignition 

zone.

Defense Zone (Zone 2): This is a quarter mile buffer around structures and other human 

developments. The goal of this zone is to create an environment where firefighters can safely and 

effectively suppress wildfires by treating fuels and vegetation to reduce flame heights below four 

feet and have no crown fire under 90th percentile weather conditions on 100 percent of the land 

base (USDA USDI 2001 and Nowicki 2002).

Threat Zone (Zone 3): This is a 1.5 mile buffer around structures and other human 

developments. The goal of this zone is to treat fuels and vegetation to reduce crown fire to a 

surface fire before reaching the community fire defense zone under 90th percentile weather 
Fire and Fuels Craggy Vegetation Management Project

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conditions (USDA USDI 2001). Research suggests (Finney 2001, and Schmidt et al. 2008) that 

at least 20 percent of the land base should be strategically treated to increase landscape level fire 

resilience.

Figure 1: Wildland Urban Interface Zones

*(figure not to scale)

Flame length potential in the wildland urban interface zones is an indicator of how effective 

treatments are within each zone. Flame length potential may also be used as a proxy for 

community safety or resilience to wildfire. Nowicki (2002) states “The protection of houses and 

communities from the threat of forest fire depends upon the proper treatment of the wildlandurban interface, the area directly adjacent to houses and communities. The protection of the 

house depends entirely on treatment of the home ignition zone......regardless of what treatments 

are implemented in the adjacent forest.” Cohen (2008) also notes that the home ignition zone 

principally determines a home’s ignition potential.

Lowering flame lengths to a level conducive to safe and effective firefighting is the main goal of 

fuel reduction in the wildland urban interface. In order to reduce both direct flame impingement 

and resulting home ignition, as well as to provide space for firefighters to suppress the fire 

directly, the 100-foot home ignition zone should have flame lengths of two feet or less. In the 

surrounding quarter mile defense zone, flame lengths of four feet or less are essential in 

providing an extra buffer for firefighter safety, and lessen the chances of firebrands from nearby 

vegetation igniting structures. Fuel reduction in the outlying 1.5 mile threat zone can help to 

lower the intensity of an approaching front into the defense zone, but does not have a noticeable 

effect on reducing home ignitions. Strategically based treatments, such as on ridgelines and 

roads, help reduce fire behavior in areas often utilized by fire suppression resources. In addition, 

roads serve as important ingress and egress routes during emergencies such as wildfire and may 

serve as alternative routes for safety and evacuation if needed.
Fire and Fuels Craggy Vegetation Management Project

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The analysis will show current conditions in various time periods. To display outputs from 

modeling results, short-term effects for all alternatives are displayed at five years in the future,

mid-term effects are ten years, and long-term effects are greater than twenty years. Effects are 

shown for these time periods whether or not any treatments occur. After approximately twenty

years, and in some cases sooner, modeling indicates fuels treatments are no longer display an 

effect on reducing fire and there is a potential need for maintenance in order for treatments to 

continue to stay effective. Therefore, even though the Silviculture resource report indicates that 

the project actions will have an effect on stand density for 20 years or more, displaying the 

results of alternatives on fire and fuels for 20 years or more would not provide meaningful 

information for comparison of effects on fire hazard and fuel behavior potential and is not 

included in tables in this report.

Affected Environment

Affected Environment for the Project Area

In the general area that includes the project area, fire has played a major role in shaping 

vegetation composition and structure (Agee 2007, Skinner et al. 2006, Taylor and Skinner 1998). 

Historically, the montane ecological zones are characterized by frequent fires of low- to mixedseverity (Skinner et al. 2006, Taylor and Skinner 1998). Lightning, European settlers and 

American Indian-ignited fires were the primary factors shaping the vegetation (Taylor and 

Skinner 1998).

Stand and vegetation structures along with severity patterns within this regime are highly 

dependent on the complex combination of topography, vegetation and climate in the area (Agee 

2007, Skinner et al. 2006). Generally, upper slope positions and south- and west-facing slopes 

burn at higher frequencies and with higher severities than lower slope positions and north- and 

east-facing slopes (Weatherspoon and Skinner 1995, Taylor and Skinner 1998, Skinner et al. 

2006, Jimerson and Jones 2003). Spatial variation in soil productivity, in conjunction with steep 

gradients of elevations and aspects, controls the rates of fuel accumulation (Skinner et al. 2006).

Disturbance history affects the fuel profile and is linked to severity patterns on the landscape 

(Miller et al. 2009, Alexander et al. 2006).

The steep and complex landscape creates a unique interaction with fire weather and elevation 

during the hot, dry summers when a high pressure system prevails and smoke does not dissipate; 

this often results in temperature inversions. While these inversions can lead to benign fire 

behavior, they can also create public health issues and concerns over high densities of smoke 

particulates that cover large areas and can persist for many days. When the temperature 

inversions are broken by high winds, fire behavior can increase significantly, resulting in large 

areas of high-severity fire.

Numerous fire starts still occur in the project area. However, with the onset of fire suppression in 

the early 1900s and increased effectiveness of suppressing fires with mechanized equipment (fire 

engines, dozers, aircraft, etc.) in later years, most of the fires are kept small. As a result, forest 

vegetation has changed from a heterogeneous pattern to a more homogeneous pattern of smaller 

openings in a matrix of denser forests (Skinner et al. 2006). Therefore, one of the most extensive 

problems related to the health of this watershed is the over-accumulation of vegetation and fuel 

loading due to a lack of disturbance from fire. Although severity patterns are still largely 

dependent on physical factors (e.g. slope position, aspect, slope percentage, elevation, etc.), the 
Fire and Fuels Craggy Vegetation Management Project

8

current vegetation composition and structure have created conditions that increase the likelihood 

of larger areas of intense and severe fire (Skinner et al. 2006, Taylor and Skinner 2003, Scott and 

Reinhardt 2001).

Much of the current vegetation conditions in the project area are an artifact of the 1955 Haystack 

Fire which burned most of the area (see the silviculture resource report available on the project 

website for further information). Since 1955, only about 3,100 acres have burned in wildfires

within the project boundary. As a result, the need for action in the project area evolved primarily 

from changes in fire regimes over the last century. Historically, low- to mixed-severity fires in 

the area played a significant role in creating a high spatial complexity of vegetation including 

openings of different sizes, forested stands that were generally more open and late-successional, 

and closed-canopy forests. Fire suppression, along with other past management activities in the 

project area, has resulted in uncharacteristically dense vegetation and high fuel loading, a decline 

in wildlife forage and habitat diversity, and an elevated risk of high-severity, stand-replacing

fires including areas adjacent to communities.

The project area is located in an area of a high concentration of lightning strikes but fire 

suppression has largely eliminated large fires in the project area. As a result, 80 percent of the 

project area is moderately or severely departed from historic fire return intervals. In other words, 

most of the Craggy Project area has missed four or more fire return intervals since suppression 

began on the Forest; 90 percent of the project area has not been burned by wildfire since the 

1955 Haystack Fire.

Current concerns focus on high fire hazard (as defined by fuel loading and vegetation densities) 

and high fire risk (as defined by fire start occurrence) over time. Fire risk and associated fire 

hazard have led to concerns over fire behavior in and adjacent to private property and fire effects 

to resource values on Forest land (e.g. wildlife habitat, soil stability, human uses, hydrology, air 

quality). In addition, smoke from large fires that does not disperse has the potential to negatively 

impact the project area which has a high level of human use.

Many of these concerns have been validated by recent wildfires near the project boundary (e.g. 

the 2016 Grade Fire, the 2014 Happy Camp Complex fires, the 2014 Beaver fire and the 2006 

Humbug Fire). The 2014 fires were driven by heavy fuels accumulation, weather conditions, 

limited access for firefighting forces, rugged terrain, and many other factors that contribute to 

large fire growth. During these fires, structures were lost and air quality standards exceeded the 

California Air Resource Board thresholds. In addition, areas of high fire severity experienced 

soil erosion, loss of wildlife habitat and degraded other natural resources. In 2006, the Humbug 

fire threatened the town of Yreka, growing to about 40 acres. More recently, the 2016 Grade Fire 

burned approximately 750 acres at the north end of Yreka; it destroyed structures and

infrastructure and threatened more. Similar vegetation conditions exist in the project area as 

those experienced in these recent wildfires. Risk of wildfire is likely the largest natural disaster 

threat to the communities within and adjacent to the Craggy project area.

According to the Yreka Area Fire Safe Council Community Wildfire Protection Plan (Yreka 

CWPP 2013), more than 80 percent of the fire safe council area is at very high risk of significant 

damage from wildfire. There are approximately 3,655 landowner parcels within the fire council 

area. The Craggy Project Area encompasses portions of this fire safe council area and is aimed at 

reducing the fire risk as identified within the CWPP on Forest System lands.
Fire and Fuels Craggy Vegetation Management Project

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According to the Forest geographic information system layers, a total of 72 fire starts have 

occurred within the project boundary over an almost 30-year analysis period (1985 to 2015). 

This is an average of about 2.4 fires per year. Out of the 72 fire starts, 58 were lightning-caused 

and 14 were human-caused.

Large fire history (fires greater than 10 acres) shows that approximately 63,727 acres have 

burned within the project boundary since 1905. This indicates that many acres burned multiple 

times. However, only 3,100 acres have burned since 1955.

Figure 2: Areas Within the Project Area that have Burned Prior to and after 1955
Fire and Fuels Craggy Vegetation Management Project

10

Fire Hazard Measured by Flame Length

Table 3 below displays current predicted flame lengths in the project area under 90th percentile 

weather conditions.

Table 3: Flame Length Potential for the Project Area for Alternative 1 in Acres and Percent of the Project 

Area

Percentile 

Weather Low (0-4 feet) Moderate (4-8feet) High (8-11 feet) Very High (greater than 11 feet)

90th Percentile 5,262 (18%) 5,497 (19%) 7,413 (25%) 11,544 (39%)

Fire Type (Surface, Passive Crown or Active Crown Fire)

Table 4 below displays fire type in the project area under 90th percentile weather conditions.

Table 4: Fire Type Potential for the Project Area for Alternative 1 in Acres and Percent of the Project Area.

Percentile Weather Surface Fire Passive Crown Fire Active Crown Fire

90th Percentile 18,987 (64%) 8,111 (27%) 2,618 (9%)

Fire Regime Impacts to Vegetation

The fire regime is the most widespread and dynamic disturbance regime affecting the analysis 

area. Numerous fire starts occur within the analysis area every year. Fires occurring in the area 

affect vegetation communities with varying severities. Patterns of fire severity can be attributed 

to vegetation type, solar radiation, weather patterns, and slope positions. Upper slopes, ridgetops, 

and south and west facing aspects typically experience higher fire severity. As a result, shrubs 

and fire adapted species such as knobcone pine and other even-aged trees dominate such areas. 

Lower slopes and north and east facing aspects typically experience lower fire severity. These 

areas typically have multi-aged stands and burn with less frequency. With lower fuel loadings, 

landscape features such as streams and ridgetops are often sufficient to impede fire spread.

Current vegetation patterns are also attributed to disturbance history. Much of the analysis area 

(nearly 90 percent) has been fire free since 1955. As a result, the build-up of ladder and surface 

fuels has increased the probability of high severity stand replacing fire. Although current 

vegetation and severity patterns are largely dependent on factors mentioned above, large patches 

of high severity fire have been observed in areas that typically burned at low severity in recent 

burns near the project area. Therefore, current vegetation patterns and seral stage distribution 

have changed significantly since the onset of the fire suppression era approximately 100 years 

ago.

An analysis was conducted to determine current fire behavior potential on dominant vegetation 

communities and size class. This was done to get a better understanding of potential fire effects 

on current vegetation types and size class distribution as shown in Tables 5 and 6.
Fire and Fuels Craggy Vegetation Management Project

11

Table 5: Fire Behavior Potential on Dominant Vegetation Type for the Project Area for Alternative 1 in 

Acres

Dominant Vegetation Type Low (0-4

feet)

Moderate (4-8

feet)

High (8-11

feet)

Very High (greater 

than 11 feet)

Annual Grass 235 213 216 556

Barren 322 0 0 0

Douglas Fir 848 701 982 1,566

Mixed Chaparral 824 1,867 1,614 2,950

Montane Chaparral 319 441 937 1,350

Montane Hardwood Conifer 324 327 454 870

Montane Hardwood 464 416 746 1,091

Montane Riparian 30 24 14 29

Perennial Grass 80 126 56 74

Ponderosa Pine 302 279 237 322

Sagebrush 19 12 7 7

Sierran Mixed Conifer 1,455 896 1,922 2,633

White Fir 164 43 40 51

Total 5,386 5,345 7,225 11,499

The dominant vegetation type from the EVEG GIS layer was used for this analysis.

Table 6: Fire Behavior Potential on Size Class for the Project Area for Alternative 1 in Acres

Size Class (diameter) Low (0-4 feet) Moderate (4-8 feet) High (8-11 feet) Very High

(greater than 11 feet)

1-5.9 inches 226 357 154 123

6-10.9 inches 119 221 222 289

11-23.9 inches 1,146 1,069 1,842 2,574

Greater than 24 inches 1,882 1,180 2,074 3,244

Total 3,373 2,827 4,292 6,230

Affected Environment for the Wildland Urban Interface

Table 7 below shows the acres of Forest lands and private lands by wildland urban interface zone 

within the project area.

Table 7: Forest and Private Lands by Wildland Urban Interface Zone within the Project Area.

Wildland Urban Interface Federal Acres Private Acres Total Acres % Federal

Home Ignition Zone 49 160 209 23

Defense Zone 1,035 1,110 2,145 48

Threat Zone 17,259 4,622 21,881 79

Total Wildland Urban Interface Acres 18,343 5,892 24,235 76
Fire and Fuels Craggy Vegetation Management Project

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Table 8 below depicts flame length potential within each wildland urban interface zone under 

current conditions and under 90th percentile weather conditions.

Table 8: Current Flame Length Potential within the Wildland Urban Interface Zone

Flame Lengths Home Ignition 

Zone (Acres)

Defense Zone 

(Acres)

Threat Zone 

(Acres)

Low (0-4 feet) 12 207 2,874

Moderate (4-8 feet) 6 126 3,183

High (8-11 feet) 9 297 4,387

Very High (greater than 11 feet) 22 405 6,812

Total 49 1,035 17,256

Environmental Consequences

Alternative 1

Direct and Indirect Effects in the Project Area and Wildland Urban Interface

Under Alternative 1, there will be no direct effects. The continued level of management and use 

will occur. Proposed treatments will not occur, and the desired conditions for the project area and 

wildland urban interface will not be reached. Fire hazard potential (flame length potential and 

fire type) and fire effects to vegetation will remain as described in the affected environment.

Without the influence of silviculture and fuels treatments, and fire under prescribed conditions to 

restore and maintain vegetation diversity, many stands will continue to have decreasing

resilience to the current fire regime and will exhibit an increase in susceptibility to insects and 

disease. Other stands are likely to continue to lose their structural and compositional diversity.

Indirectly, taking no action allows the current fuel loading conditions to continue in an 

increasingly negative manner. As vegetation continues to grow with no management actions and 

no reduction in fuel loading, fuels will continue to accumulate away from desired conditions and 

potentially increase due to tree mortality. An increasing percentage of the project area will gain 

the potential for high flame lengths, which correlates with uncharacteristically high severity fire. 

The dominant vegetation type would likely change in many areas from a forested condition to 

brush fields due to tree mortality and this will decrease available seed trees that provide natural 

reforestation. As a result, size class would also decrease on average across the project area. 

Without strategically placing treatments, there would continue to be a heightened threat to the 

communities within and adjacent to the project area and within the wildland urban interface. 

Other resource specialists will discuss the impacts of these high fire severity effects on other 

values within the project boundary, including watershed, timber products, and wildlife.

Cumulative Effects

Vegetation structure will continue to change over time, leading to increased fire hazard as stands 

of trees and vegetation continue to grow denser and fuel loading increases. As a result, fire type, 

flame length potential, and fire effects to vegetation are also likely to increase. In addition, the 

fire threat to communities will continue to be high and increase over time as fuel loading and 

vegetation density increases. The effects of other ongoing and reasonably foreseeable actions 
Fire and Fuels Craggy Vegetation Management Project

13

within the project area, including timber harvest and various fuels treatments on private and 

public land (see Appendix C of the Craggy Environmental Impact Statement), will likely 

decrease the density of trees in the watershed, reduce ladder fuels, and slightly decrease the 

likelihood of crown fire and flame length potential, and therefore reduce the risk of wildfire to 

private property and resources. However, adding these effects to Alternative 1 will have less than 

significant cumulative impacts on the increased fire hazard in the project area and the area within 

the wildland urban interface over the next 20 years because of the limited scale of these projects.

Alternative 2

Direct and Indirect Effects in the Project Area

Under Alternative 2, 10,600 acres of treatment in the 29,500-acre project area will lead the 

project area (both in treated areas and adjacent stands) toward resilient forest conditions. These 

effects are demonstrated in Tables 9 through 12 below.

Table 9: Flame Length Potential for the Project Area for Alternative 2 in Acres and Percent of the Project 

Area

Flame Length Short-term Post-Treatment (5 years) Mid-term Post-treatment (10 years)

0-4 feet 16,329 (55%) 11,178 (38%)

4-8 feet 6,264 (21%) 9,755 (33%)

8-11 feet 1,204 (4%) 1,718 (5%)

Greater than 11 feet 5,884 (20%) 7,029 (24%)

Table 10: Fire Type Potential for the Project Area for Alternative 2 in Acres and Percent of the Project Area

Fire Type Short-term Post-Treatment (5 years) Mid-term Post-treatment (10 years)

Surface 22,437 (79%) 20,140 (68%)

Passive Crown 4,932 (17%) 7,633 (26%)

Active Crown 1,311 (4%) 1,908 (6%)

Table 11: Fire Behavior Potential on Dominant Vegetation Type for the Project Area for Alternative 2, in 

Acres

Dominant Vegetation Type Low (0-4 feet) Moderate (4-8

feet)

High (8-11

feet)

Very High (greater 

than 11 feet)

Annual Grass 680 199 5 335

Barren 322 0 0 0

Douglas Fir 2,414 297 70 1,316

Mixed Chaparral 3,269 1,692 113 2,182

Montane Chaparral 926 701 90 1,330

Montane Hardwood Conifer 930 265 37 743

Montane Hardwood 973 598 50 1,090

Montane Riparian 51 16 1 30

Perennial Grass 198 107 2 29
Fire and Fuels Craggy Vegetation Management Project

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Dominant Vegetation Type Low (0-4 feet) Moderate (4-8

feet)

High (8-11

feet)

Very High (greater 

than 11 feet)

Ponderosa Pine 785 142 33 180

Sagebrush 41 2 1 1

Sierran Mixed Conifer 4,230 830 154 1,690

White Fir 189 38 10 60

Total 15,008 4,887 566 8,986

Table 12: Fire Behavior Potential on Size Class for the Project Area for Alternative 2 in Acres

Size Class

(diameter in inches) Low (0-4 feet) Moderate (4-8 feet)

High (8-11

feet)

Very High (greater 

than 11 feet)

1-5.9 inches 684 99 1 76

6-10.9 inches 424 200 20 207

11-23.9 inches 3,370 1,037 134 2,090

Greater than 24 inches 4,645 852 158 2,725

Total 9,123 2,188 313 5,098

After completion of the treatments, there is an increase of 37 percent (55 percent total) of the 

project area meeting desired conditions for flame lengths less than four feet, and an increase of 

15 percent (79 percent total) of the area meeting desired conditions for surface fire type. This is 

important because these flame lengths and fire types allow the use of the most effective 

strategies for containing wildfires (including direct attack with hand crews). Also, flame lengths 

of four feet or less are specified in the Forest Plan as being the threshold for low fire hazard. For 

this modeling, it was assumed that all of the treatments are implemented in the same year. This 

may not be possible to achieve; however, there is no way to accurately predict when and in what 

order treatments will be implemented. Because of this, assuming all treatments are implemented 

in the same year is the only way to make comparisons across the various alternatives.

In fuel breaks and thinning without product removal units where pile burning would occur, fire 

would be allowed to underburn within the designated unit at low intensity if there is low risk of 

burning onto private property. Measures will be included in the prescribed burn plan to minimize 

the risk of fire escaping designated units. This also applies to the wildland urban interface area 

which is described below.

Direct and Indirect Effects in the Wildland Urban Interface Area

Since the threat zone includes both defense and home ignition zones, the total number of acres of 

wildland urban interface that would be affected by the project is about 17,260 acres. Under 

Alternative 2, 10,600 acres of treatment would help to create resilient forest conditions in the 

wildland urban interface as displayed in Tables 13 and 14. Having flame lengths of less than four 

feet is particularly important in the wildland urban interface to allow direct attack of wildfires. In 

71 percent of the home ignition zone, 50 percent of the defense zone, and 50 percent of the threat 

zone will meet desired conditions in the short-term. Over the mid-term, treatment effectiveness 

for meeting desired conditions declines to 55 percent for the home ignition zone, 38 percent for 

the defense zone, and 39 percent for the threat zone; however, this is a substantial increase from 

Alternative 1 in acres meeting desired conditions from the Forest Plan. Due to the Craggy Project 
Fire and Fuels Craggy Vegetation Management Project

15

focusing primarily on the defense and threat zones (including areas adjacent to private land and 

the home ignition zone), this allows work on private lands to build upon the Craggy Project’s 

fuels treatments for community and structure protection from wildfire.

Table 13: Short-term Flame Length Potential within the Wildland Urban Interface under Alternative 2

Flame Lengths Home Ignition Zone (Acres) Defense Zone (Acres) Threat Zone (Acres)

Low (0-4 feet) 35 508 8,579

Moderate (4-8 feet) 3 154 2,870

High (8-11 feet) 1 12 330

Very High (greater than 

11 feet) 11 361 5,477

Total 49 1,035 17,256

Table 14: Mid-term Flame Length Potential within the Wildland Urban Interface under Alternative 2

Flame Lengths Home Ignition Zone (Acres) Defense Zone (Acres) Threat Zone (Acres)

Low (0-4 feet) 27 396 6,685

Moderate (4-8 feet) 12 342 6,625

High (8-11 feet) 1 72 1,051

Very High (greater than 

11 feet) 9 225 2,895

Total 49 1,035 17,256

The fuel treatment design (e.g. thinning, mastication, and fuel breaks) along with re-introducing 

fire to the project area under prescribed conditions will provide the benefits associated with lowto mixed-severity fires (e.g. fuels reduction and vegetation diversity) while minimizing the 

adverse effects often resulting from uncontrolled high-severity wildfires (e.g. effects to soils, 

wildlife habitat, structures, infrastructure and air quality).

Actions in Alternative 2 provide a substantial benefit to the wildland urban interface by 

increasing the number of acres in which low and moderate flame lengths are expected to occur 

and decreasing substantially the number of acres in which high and very high flame lengths are 

expected. In addition, this will increase firefighter suppression capability within the wildland 

urban interface as well as decrease the likelihood in which structures are damaged or destroyed.

Treatments near routes that allow firefighters and the public to enter or leave the project area 

(ingress and egress), especially roadside fuelbreaks, would provide increased safety for 

firefighters entering the area and allow for safer evacuation if necessary for the public.

Thinning will increase canopy base heights making it more difficult for fire to get into tree 

crowns and promoting more surface fire type. Mastication, in which units primarily consist of 

brush, re-arranges the fuel bed from standing brush to finer fuels on the surface floor. Many of 

the proposed units are fuel reduction maintenance areas from previous projects within the 

Craggy Project area. In comparing pre- versus post- treatments in these units, fire type in treated 

and maintained areas are anticipated to stay a surface fire with flame lengths less than four feet.

Fuel loads of masticated fuel beds for these previous projects have not shown to be a concern for 

undesired fire effects in the event of a wildfire or during prescribed fire for the project area.
Fire and Fuels Craggy Vegetation Management Project

16

Figure 3: Mastication of Brush from the Yreka Project in 2002. This Unit is proposed for Maintenance and 

Re-entry for the Craggy Project and Serves as part of a Key Ridge System for the Fuels Strategy and is 

within the Wildland Urban Interface.

Cumulative Effects

Adding the effects of the reasonably foreseeable future fuel reduction treatments displayed in 

Appendix C of the Craggy Environmental Impact Statement, to the effects of this alternative will 

decrease flame lengths and move toward less crown fire where similar treatments are proposed, 

but will not produce significant cumulative effects. Some future actions such as fuel reduction

treatments on the Bureau of Land Management Lands and timber harvest and fuels reduction on 

private lands will have some beneficial effects. These projects are anticipated to benefit the 

analysis indicators as in some locations they tie into work proposed in Alternative 2 and the 

treatments will complement each other. In addition, treatments reducing fuel loading, fire type, 

and flame length would benefit the area being treated, including the wildland urban interface. 

Therefore, there will be some benefit to the analysis indicators from these projects for fire and 

fuels within the Craggy Project.
Fire and Fuels Craggy Vegetation Management Project

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Alternative 3

Direct and Indirect Effects in the Project Area

Alternative 3 proposes to treat about 11,310 acres. This alternative has similar effects on flame 

lengths and fire type to those of Alternative 2 with some differences due to some stands being 

treated in Alternative 2 that are not treated in Alternative 3, and additional fuels treatments 

adjacent to private lands in Alternative 3. However, these differences are minor in effects on fire 

resiliency over the landscape. For these reasons, the direct and indirect effects are similar to

Alternative 2 as displayed in Tables 15 through 18.

Table 15: Flame Length Potential for the Project Area for Alternative 3 in Acres and Percent of the Project 

Area

Flame Length Short-term Post-Treatment Mid-term Post-treatment

0-4 feet 17,275 (58%) 16,997 (57%)

4-8 feet 5,704 (19%) 5,969 (20%)

8-11 feet 1,161 (4%) 1,166 (4%)

Greater than 11 feet 5,541 (19%) 5,549 (19%)

Table 16: Fire Type Potential for the Project Area for Alternative 3 in Acres and Percent of the Project Area

Fire Type Short-term Post-Treatment Mid-term Post-treatment

Surface 23,605 (80%) 21,107 (71%)

Passive Crown 4,852 (16%) 6,859 (23%)

Active Crown 1,215 (4%) 1,714 (6%)

Table 17: Fire Behavior Potential on Dominant Vegetation Type for the Project Area for Alternative 3, in 

Acres

Dominant Vegetation Type Low (0-4 

feet)

Moderate (4-8 

feet)

High (8-11 

feet)

Very High (greater 

than 11 feet)

Annual Grass 774 122 5 319

Barren 322 0 0 0

Douglas Fir 2,513 829 413 342

Mixed Chaparral 3,727 1,313 57 2,159

Montane Chaparral 1,247 921 122 757

Montane Hardwood Conifer 1,080 436 97 362

Montane Hardwood 1,197 682 106 726

Montane Riparian 66 15 0 17

Perennial Grass 252 41 13 30

Ponderosa Pine 878 137 37 88

Sagebrush 43 1 1 0

Sierran Mixed Conifer 4,871 1,026 298 709

White Fir 267 11 8 11
Fire and Fuels Craggy Vegetation Management Project

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Dominant Vegetation Type Low (0-4 

feet)

Moderate (4-8 

feet)

High (8-11 

feet)

Very High (greater 

than 11 feet)

Total 17,237 5,534 1,157 5,520

Table 18: Fire Behavior Potential on Size Class for the Project Area for Alternative 3 in Acres

Size Class (diameter in 

inches)

Low (0-4 

feet)

Moderate (4-8 

feet)

High (8-11 

feet)

Very High (greater 

than 11 feet)

1-5.9 inches 685 116 13 46

6-10.9 inches 510 207 13 121

11-23.9 inches 3,942 1,249 259 1,181

Greater than 24 

inches 5,489 1,456 567 868

Total 10,626 3,028 852 2,216

After completion of the treatments, there is an increase of 40 percent (58 percent total) of the 

project area meeting desired conditions for flame lengths less than four feet, and an increase of 

16 percent (80 percent total) of the area meeting desired conditions for surface fire type. This is 

important because this is the flame length and fire type that allows for the use of direct attack of 

a wildfire with hand crews and the most effective strategy for containing wildfires. Also, flame 

lengths of four feet or less are specified in the Forest Plan as being the threshold for low fire 

hazard. For this modeling, it was assumed that all of the treatments are implemented in the same 

year. This may not be possible to achieve; however, there is no way to accurately predict when 

and in what order treatments will be implemented. Because of this, assuming all treatments are 

implemented in the same year is the only way to make comparisons across the various 

alternatives.

Direct and Indirect Effects in the Wildland Urban Interface Area

Under Alternative 3, 11,310 acres of treatment would help to create resilient forest conditions in 

the wildland urban interface as displayed in Tables 19 and 20. As noted for Alternative 2, having 

flame lengths of less than four feet is particularly important in the wildland urban interface to 

allow direct attack of wildfires. In 92 percent of the home ignition zone, 75 percent of the 

defense zone, and 61 percent of the threat zone will meet desired conditions in the short and midterm. This is a substantial increase from Alternative 1 in acres meeting desired conditions from 

the Forest Plan but very similar to the effects of Alternative 2.

Table 19: Short-term Flame Length Potential within the Wildland Urban Interface under Alternative 3

Flame Lengths Home Ignition Zone (Acres) Defense Zone (Acres) Threat Zone (Acres)

Low (0-4 feet) 45 770 10,540

Moderate (4-8 feet) 1 95 3,111

High (8-11 feet) 0 28 722

Very High (greater 

than 11 feet) 3 142 2,883

Total 49 1,035 17,256
Fire and Fuels Craggy Vegetation Management Project

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Table 20: Mid-term Flame Length Potential within the Wildland Urban Interface under Alternative 3

Flame Lengths Home Ignition Zone (Acres) Defense Zone (Acres) Threat Zone (Acres)

Low (0-4 feet) 43 757 10,406

Moderate (4-8 feet) 3 107 3,238

High (8-11 feet) 0 28 724

Very High (greater 

than 11 feet) 3 143 2,888

Total 49 1,035 17,256

Cumulative Effects

Adding the effects of the reasonably foreseeable future fuel reduction treatments to the effects of 

this alternative will be similar to those described for Alternative 2.

Comparison of Alternatives

Alternatives are compared below for the project area and for the wildland urban interface area.

Comparison of Alternatives for the Project Area

Table 21 and Table 22 (short-term) and Table 23 and table 24 (mid-term) compare the potential 

flame length and fire type for the project area by alternative.

Table 21: Flame Length Potential (short-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives

Flame Length Alternative 1 Alternative 2 Alternative 3

0-4 feet 5,262 (18%) 16,329 (55%) 17,275 (58%)

4-8 feet 5,497 (19%) 6,264 (21%) 5,704 (19%)

8-11 feet 7,413 (25%) 1,204 (4%) 1,161 (4%)

Greater than 11 feet 11,544 (39%) 5,884 (20%) 5,541 (19%)

Table 22: Fire Type Potential (short-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives

Fire Type Alternative 1 Alternative 2 Alternative 3

Surface 18,987 (64%) 22,437 (79%) 23,605 (80%)

Passive Crown 8,111 (27%) 4,932 (17%) 4,852 (16%)

Active Crown 2,618 (9%) 1,311 (4%) 1215 (4%)

Table 23: Flame Length Potential (mid-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives

Flame Length Alternative 1 Alternative 2 Alternative 3

0-4 feet 5,262 (18%) 11,187 (38%) 16,997 (57%)

4-8 feet 5,497 (19%) 9,755 (33%) 5,969 (20%)
Fire and Fuels Craggy Vegetation Management Project

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Flame Length Alternative 1 Alternative 2 Alternative 3

8-11 feet 7,413 (25%) 1,718 (5%) 1,166 (4%)

Greater than 11 feet 11,544 (39%) 7,029 (24%) 5,549 (19%)

Table 24: Fire Type Potential (mid-term) in the Project Area for Alternative 1 Compared to Action 

Alternatives

Fire Type Alternative 1 Alternative 2 Alternative 3

Surface 18,987 (64%) 20,140 (68%) 21,107 (71%)

Passive Crown 8,111 (27%) 7,633 (26%) 6,859 (23%)

Active Crown 2,618 (9%) 1,708 (6%) 1,714 (6%)

Table 25 and Table 26 compare the fire behavior potential on dominant vegetation type and size 

class for the project area under Alternative 1, and post-treatment for Alternatives 2 and 3.

Table 25: Fire Behavior Potential (flame length) on Dominant Vegetation Types in Acres, Comparing Shortterm Effects for Alternatives

Alternatives Alternative 1 Alternative 2 Alternative 3

Dominant 

Vegetation 

Type

Low (0-

4')

Moderate 

(4-8’)

High (8-

11’)

Very High 

(> 11')

Low (0-

4')

Moderate 

(4-8’)

High 

(8-11’)

Very High 

(> 11')

Low (0-

4')

Moderate 

(4-8’)

High 

(8-11’)

Very High 

(> 11')

Annual 

Grass

235 213 216 556 680 199 5 335 774 122 5 319

Barren 322 0 0 0 322 0 0 0 322 0 0 0

Douglas Fir 848 701 982 1,566 2,414 297 70 1,316 2,513 829 413 342

Mixed 

Chaparral 824 1,867 1,614 2,950 3,269 1,692 113 2,182 3,727 1,313 57 2,159

Montane 

Chaparral 319 441 937 1,350 926 701 90 1,330 1,247 921 122 757

Montane 

Hardwood 

Conifer

324 327 454 870 930 265 37 743 1,080 436 97 362

Montane 

Hardwood 464 416 746 1,091 973 598 50 1,090 1,197 682 106 726

Montane 

Riparian

30 24 14 29 51 16 1 30 66 15 0 17

Perennial 

Grass

80 126 56 74 198 107 2 29 252 41 13 30

Ponderosa 

Pine

302 279 237 322 785 142 33 180 878 137 37 88

Sagebrush 19 12 7 7 41 2 1 1 43 1 1 0

Sierran 

Mixed 

Conifer

1,455 896 1,922 2,633 4,230 830 154 1,690 4,871 1,026 298 709

White Fir 164 43 40 51 189 38 10 60 267 11 8 11

Total 5,386 5,345 7,225 11,499 15,008 4,887 566 8,986 17,237 5,534 1,157 5,520
Fire and Fuels Craggy Vegetation Management Project

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Table 26: Fire Behavior Potential on Vegetation Size Class for Current Condition as Displayed for 

Alternative 1 Compared to Action Alternatives in the Short Term

Alternatives Alternative 1 Alternative 2 Alternative 3

Size Class 

(diameter)

Low 

(0-4')

Moderate 

(4-8’)

High 

(8-11’)

Very 

High 

(> 11')

Low 

(0-4')

Moderate 

(4-8’)

High (8-

11’)

Very 

High (>

11')

Low (0-

4')

Moderate 

(4-8’)

High 

(8-11’)

Very 

High (> 

11')

1-5.9 inches 226 357 154 123 684 99 1 76 685 116 13 46

6-10.9 inches 119 221 222 289 424 200 20 207 510 207 13 121

11-23.9 inches 1,146 1,069 1,842 2,574 3,370 1,037 134 2,090 3,942 1,249 259 1,181

Greater than 

24 inches 1,882 1,180 2,074 3,244 4,645 852 158 2,725 5,489 1,456 567 868

Total 3,373 2,827 4,292 6,230 9,123 2,188 313 5,098 10,626 3,028 852 2,216

For the action alternatives, the fuel treatment design (e.g. thinning, mastication, and fuel breaks) 

along with the re-introducing fire to the project area under prescribed conditions will provide the 

benefits associated with low- to mixed-severity fires (e.g. fuels reduction and vegetation 

diversity) while minimizing the adverse effects often resulting from uncontrolled high-severity 

wildfires (e.g. effects to soils, wildlife habitat, infrastructure and air quality). While Alternative 3 

provides more acres of low flame lengths and surface fire type than does Alternative 2, the 

greatest differences in benefits are between Alternative 1 and the action alternatives.

Comparison of Alternatives for the Wildland Urban Interface

Table 27 (short-term) and Table 28 (mid-term) compare the flame length potential within the 

wildland urban interface under the Alternative 1 and post-treatment for action alternatives.

Table 27: Flame Length Potential (short-term) in the Wildland Urban Interface for Alternative 1 Compared 

to Action Alternatives

Alternatives Alternative 1 Alternative 2 Alternative 3

Flame 

Lengths 

(Feet)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Low (0-4') 12 207 2,874 35 508 8,579 45 770 10,540

Moderate 

(4-8') 6 126 3,183 3 154 2,870 1 95 3,111

High (8-11') 9 297 4,387 1 12 330 0 28 722

Very High 

(>11') 22 405 6,812 10 361 5,477 3 142 2,883

Total 49 1,035 17,256 49 1035 17,256 49 1,035 17,256
Fire and Fuels Craggy Vegetation Management Project

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Table 28: Flame Length Potential (mid-term) in the Wildland Urban Interface for Alternative 1 Compared to 

Action Alternatives

Alternatives Alternative 1 Alternative 2 Alternative 3

Flame 

Lengths

(Feet)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Home 

Ignition 

Zone 

(Acres)

Defense 

Zone 

(Acres)

Threat 

Zone 

(Acres)

Low (0-4') 12 207 2,874 27 396 6,685 43 757 10,406

Moderate (4-

8') 6 126 3,183 12 342 6,625 3 107 3,238

High (8-11') 9 297 4,387 1 72 1,051 0 28 724

Very High 

(>11') 22 405 6,812 19 225 2,895 3 143 2,888

Total 49 1,035 17,256 49 1035 17,256 49 1,035 17,256

Action alternatives provide a substantial benefit to the wildland urban interface by increasing the 

number of acres in which low and moderate flame lengths are expected to occur and decreasing 

substantially the number of acres in which high and very high flame lengths are expected. In 

addition, this will increase firefighter suppression capability within the wildland urban interface

as well as decrease the likelihood in which structures are damaged or destroyed. For the wildland 

urban interface, some of the most important work adjacent to homes is currently being planned 

as displayed in Appendix C of the Craggy Environmental Impact Statement. Combined 

strategically-placed treatments on both private and public lands would ultimately reduce the 

probability of devastating effects from wildfire on homes, infrastructure, and resources.

Compliance with law, regulation, policy, and the Forest Plan

All alternatives are consistent with the Forest Plan standards and guidelines related to fire and 

fuels as noted on the Forest Plan consistency checklist, available on the project website. All 

alternatives are also consistent with the law, regulation and policy referenced in the methodology 

section of this report.
Fire and Fuels Craggy Vegetation Management Project

23

Literature Cited

Agee, J. K. 1993. Fire ecology of Pacific Northwest forests. Island Press: Washington, D.C: pp. 

3-24.

Agee, J.K. 2007. Steward's Fork: A Sustainable Future for the Klamath Mountains. University of 

California Press. Berkeley.

Alexander, J. D., Seavey, N. E., Ralph, C. J., Hogoboom, B. 2006. Vegetation and topographical 

correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and 

California. International Journal of Wildland Fire 15. 237-245.

Anderson, H. E. 1982. Aids to Determining Fuel Models for Estimating Fire Behavior. General 

Technical Report INT-122. U.S. Department of Agriculture, Forest Service, 

Intermountain Forest and Range Experimental Station. Ogden, UT.

Brown, J.K. 1995. Fire regimes and their relevance to ecosystem management. Pages 171-178 In 

Proceedings of Society of American Foresters National Convention, Sept. 18-22, 1994, 

Anchorage, AK. Society of American Foresters, Wash. DC.

Butz, Ramona J. and Hugh Safford. 2011. A Summary of Current Trends and Probable Future 

Trends in Climate and Climate-driven Processes for the Klamath National Forest and 

Surrounding Lands. US Forest Service, Unpublished.

Cohen, J. D. 2008.The Wildland-Urban Interface Fire Problem. Forest History Today. Fall 2008.

Cruz, Miguel. G., Alexander, Martin. E., and Wakimoto, Ronald. H. 2003. Assessing canopy 

fuel stratum characteristics in crown fire prone fuel types of western North America. 

International Journal of Wildland Fire 12, 39–50.

Finney, Mark. A. 1998. FARSITE: Fire Area Simulator – model development and evaluation. 

USDA Forest Service Research Paper – Rocky Mountain Research Station.

Finney, M.A. 2001. Design of regular landscape fuel treatment patterns for modifying fire 

growth and behavior. Forest Science, 47. Pp. 219-228.

Finney, M. A. 2006. An overview of FlamMap fire modeling capabilities. In: Fuels 

management—how to measure success: conference proceedings. 2006 March 28-30; 

Portland, Oregon. Proceedings RMRS-P-41. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station: 213-220.

Fule, Peter. Z., McHugh, Charles. , Heinlein, Thomas. A., Covington, Wallace. W., 2001. 

Potential Fire behavior is reduced following forest restoration treatments. In: Vance, 

R.K., Edminster, C.B., Covington, W.W., Blake, J.A. (comps 2001). Ponderosa pine 

ecosystems restoration and conservation: steps towards stewardship. USDA Forest 

Service Proceedings, RMRS-22 28-35. Rocky Mountain Research Station, Ogden, UT.

Hann, W.J, Bunnell, D.L. 2001. Fire and land management planning and implementation across 

multiple scales. International Journal of Wildland Fire. 27pp.

Hardy, Colin C.; Schmidt, Kirsten M.; Menakis, James P., and Sampson, R. Neil. Spatial data for 

national fire planning and fuel management. International Journal of Wildland Fire. 2001; 

10(3-4):353-372.
Fire and Fuels Craggy Vegetation Management Project

24

Jimerson, T.W. and D. W. Jones. 2003. Megram: blowdown, wildfire and the effects of fuel 

treatment. Proceedings of Fire Conference 2000: he First National Congress on Fire 

Ecology, Prevention and Management. Tall Timbers Research Station. Miscellaneous 

Report No. 13:55-59.

McKelvey, K.S., C. N. Skinner, C. Chang, D. C. Erman, S. J. Husari, D. J. Parsons, J. W. van 

Wagtendonk, and C. W. Weatherspoon. 1996. An overview of fire in the Sierra Nevada. 

In Sierra Nevada Ecosystem Project: final report to Congress. Vol. II, Assessments and 

scientific basis for management options. University of California, Centers for Water and 

Wildland Resources, Davis, CA, USA. Pp. 1033-1040.

Miller, Jay D., Knapp, Eric E., Key, Carl H., Skinner, Carl N., Isbell, Clint J., Creasy, Max R., 

Sherlock, Joseph W. 2009. Calibration and validation of the relative differenced 

Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada 

and Klamath Mountains, California, USA. Remote Sensing of Environment 113: 645-

656.

Miller, J. D., Skinner, C. N., Safford, H. D., Knapp, E. E, and Ramirez, C. M. 2012. Trends and 

causes of severity, size, and number of fires in northwestern California, USA. Ecological 

Adaptions, 22(1), pp. 184-203.

National Wildfire Coordinating Group (NWCG) 2006. Fireline Handbook PMS 410-2. Appendix 

B Fire Behavior. National Interagency Fire Center. Boise, Idaho.

Nowicki, B. 2002.The Community Protection Zone: Defending Houses and Communities from 

the Threat of Forest Fire. Center for Biological Diversity. Unpublished.

Rothermel, Richard C. 1972. A mathematical model for predicting fire spread in wildland fuels. 

Res. Pap. INT-115. Ogden, UT: U.S. Department of Agriculture, Forest Service, 

Intermountain Forest and Range Experiment Station.

Safford, H. and Schmidt. 2006. Fire Regime Condition Class Version 1. Stanislaus National 

Forest. Region 5 Ecology Program, USDA Forest Service.

Scott, J. H., Reinhardt, E. D. 2001. Assessing crown fire potential by linking models of surface 

and crown fire behavior. Pap. RMRS-RP-29. Ogden, UT: U.S. Department of 

Agriculture, Forest Service Rocky Mountain Research Station.

Scott, J. H., Burgan, R. E. 2005. Standard fire behavior fuel models: a comprehensive set for use 

with Rothermel's surface fire spread model. Gen. Tech. Rep. RMRS-GTR-153. U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Schmidt, Kirsten. M., Menakis, James. P. Hardy, Colin. C., Hann, Wendel. J., Bunnell, David. L. 

2002. Development of coarse-scale spatial data for wildland fire and fuel management. 

General Technical Report, RMRS-GTR-87, U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Fort Collins, CO.

Schmidt, D.A., Taylor, A.H., Skinner, C.N. 2008. The influence of fuels treatments and 

landscape arrangements on simulated fire behavior, Southern Cascade range, California. 

Forest Ecology and Management 255 (2008) 3170-3184.
Fire and Fuels Craggy Vegetation Management Project

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Skinner, Carl N., Taylor, Alan H., Agee, James K. 2006. Klamath Mountains bioregion. In: 

Sugihara, Neil G., Van Wagtendonk, Jan W., Shaffer, Kevin E., Fites-Kaufman, Joann, 

Thode, Andrea E. (eds.) Fire in California’s ecosystems.170-194.

Stratton, Rick. D. 2004. Assessing the effectiveness of landscape fuel treatments on fire growth 

and behavior. Journal of Forestry, October/November, vol. 102, no. 7, pp. 32-40.

Taylor, A. H., Skinner, C. N. 1998. Fire history and landscape dynamics in a late successional

reserve, Klamath Mountains, California, USA. Forest Ecology and Management, 285-

301.

Taylor, A. H., Skinner, C. N. 2003. Spatial Patterns and Controls on Historical Fire Regimes and 

Forest Structure in the Klamath Mountains. Ecological Applications, 704-719.

USDA Forest Service. 1993. Klamath National Forest Humbug Landscape Analysis and Design. 

Klamath National Forest, Yreka, CA. 70 pp. + appendices.

USDA. 1995. Klamath National Forest land and resource management plan. U.S. Department of 

Agriculture, Forest Service, Klamath National Forest. Yreka, CA.

USDA USDI. 2001. 10-Year Comprehensive Strategy: A collaborative approach for reducing 

wildland fire risks to communities and the environment. U.S. Department of Interior and 

U.S. Department of Agriculture. August 2001. 21 pp.

USDI USDA. 2002. National Fire Plan, 10-Year Comprehensive Strategy: a collaborative 

approach for reducing wildland fire risks to communities and the environment –

Implementation Plan. U.S. Department of Interior and U.S. Department of Agriculture. 

May 2002. 27 pp.

USDI USDA. 2006. Protecting people and natural resources: A cohesive fuels treatment strategy. 

Washington, DC: U. S. Department of the Interior and U. S. Department of Agriculture.

Weatherspoon, P. C., Skinner, C. N. 1995. An assessment of factors associated with damage to 

tree crowns from the 1987 wildfires in northern California. Forest Science. 41, 430–451.

Westerling, A. L., H. Hidalgo, D. R. Cayan, and T. Swetnam. 2006. Warming and earlier spring 

increases western U.S. forest wildfire activity. Science, 6 July, 2006/10.1126/ 

science.1128834

Yreka Area Fire Safe Council. 2013. (Yreka CWPP). Community Wildfire Protection Plan.
Fire and Fuels Craggy Vegetation Management Project

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Appendix A – Climate and Climate Change

The climate of the project area is best described as Mediterranean, characterized by wet and, cool 

winters; and dry and; warm summers (Skinner et al. 2006). The project area is in a transition 

zone between Happy Camp, California, which receives a mean annual precipitation of 

approximately 53 inches, and Oak Knoll, California, which receives a mean annual precipitation 

of approximately 25 inches. Precipitation primarily occurs from November 1 through April 30, 

however, summer thunderstorms are common and can release significant localized rain.

Thunderstorms can also be dry with conditions that encourage fire ignition and spread from 

lightning strikes, with the summer of 2015 being the latest example of this pattern near the 

project area.

Local data derived from five weather stations in the Klamath Mountains were used to evaluate 

climate trends over an approximate 100 year period (Butz and Safford, 2011). The data suggests 

that mean annual temperature has increased by approximately two degrees Fahrenheit and 

precipitation is near the transition zone between areas of higher and lower precipitation (see 

figure 1 of Butz and Safford 2011).

Fire and Fuels under Climate Change

Data on forest fire frequency, size, total area burned, and severity all show strong increases in 

California over the last two to three decades. Westerling et al. (2006) showed that increasing 

frequencies of large fires (greater than 1000 acres) across the western United States since the 

1980’s were strongly linked to increasing temperatures and earlier spring snowmelt. Northern 

California forests have had substantially increased wildfire activity, with most wildfires 

occurring in years with early springs (Westerling et al. 2006). This increase is likely attributable 

to both climate and land-use effects. Large percentage changes in moisture deficits in Northern 

California forests, according to Westerling et al. (2006), were strongly associated with advances 

in the timing of spring, but this area also includes substantial forested area where fire exclusion, 

timber harvesting, and succession after mining activities have led to increased forest densities 

and fire risks (McKelvey et al. 1996).

Miller et al. (2012) found no temporal trend in the annual proportion of fire area burning at highseverity within fires greater than 400 hectares (almost 1,000 acres) occurring on the four 

National Forests of Northwestern California during the period of 1987 to 2008. However, mean 

and maximum fire size and total annual area burned all increased over the period from 1910 to 

2008 and regional fire rotation fell to 95 years by 2008. During 1987 to 2008, Miller et al. (2012) 

found that the percentage of high-severity fire in conifer-dominated forests of smaller average 

diameter and lower percent cover was generally higher than in forests of larger diameter and 

higher cover. For areas that burned more than once during this period, severity (a measure of the 

effect of fire on vegetation) in conifer and hardwood forests was higher the second time burned 

versus the first time burned, regardless of tree density and size class. Closed forests of medium 

and large diameter trees that had previously burned between 1921 and 1986 burned at lower 

severities than similar forests that had last burned before 1921. Miller et al.’s (2012) data showed 

that years with larger fires and greatest area burned were produced by region-wide lightning 

events, and characterized by less winter and spring precipitation than in years dominated by 

smaller human ignited fires, but the percentage of high-severity fire was generally less in regionwide lightning events (Butz and Safford 2011).
Fire and Fuels Craggy Vegetation Management Project

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Appendix B - Fire Regime and Historical Reference 

Conditions (Condition Class)

A natural fire regime is a general classification of how fire played a role in an ecosystem in the 

absence of modern human intervention but including the influence of aboriginal burning (Agee, 

1993, Brown, 1995). Coarse-scale definitions of fire regimes have been provided by Hardy et al. 

2001 and Schmidt et al. 2002 and interpreted for management of fire and fuels (Hann and 

Bunnell, 2001). The five natural (historical) fire regimes as described by historical fire frequency 

(average number of years between fires) and historical fire severity (the effect of the fire on 

dominant overstory species) are described in the following table.

Table B-1: Description of Historic Natural Fire Regimes

Historical and current vegetation classes are primarily conifer, mixed-conifer, and mixed-conifer 

and hardwood; however, differences in seral stage distribution have changed through time. The 

mean historical fire return interval within the Craggy project boundary ranges from 

approximately 11 years to 55 years, depending on biophysical setting. A biophysical setting is 

defined as a combination of vegetation and topographic features, soils, and climate variables that 

influence vegetation development. As depicted below, approximately 76 percent of the landscape 

supported vegetation at or below a fire return interval of 30 years.

Table B-2: Historic Fire Return Intervals in the Project Area

Historic Fire Return Intervals in years Acres Percent of Area

Less than or equal to 15 14,277 48

Greater than 15 and less than or equal to 30 8,343 28

Historical Natural Fire Regimes

Code Description

I 0–35-year frequency a, low and mixed severity b

II 0–35-year frequency, stand-replacement severity

III 35–100+ year frequency, low and mixed severity

IV 35–100+ year frequency, stand-replacement severity

V 200+ year frequency, stand-replacement severity

a- Fire frequency is the average number of years between fires.

b- Severity is the effect of the fire on the dominant overstory vegetation.
Fire and Fuels Craggy Vegetation Management Project

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Historic Fire Return Intervals in years Acres Percent of Area

Greater than 30 7,096 24

Total 29,716 100

An analysis was conducted to compare historical fire return intervals (pre-suppression) to 

contemporary fire return intervals (suppression era) over the analysis area. This analysis is 

known as condition class based on departure from the historic fire return interval.

The following equation is used to determine the departure of fire return intervals:

{1 minus (reference fire return interval divided by current fire return interval)} times 100

The value obtained is a percent difference, and condition class is determined using the 

LANDFIRE national scale (i.e., zero to less than 33 percent departure equals condition class 1, 

33 to less than 67 percent departure equals condition class 2, and greater than 67 percent 

departure equals condition class 3. Other assumptions come from Safford and Schmidt, 2006. 

Figure 3 below depicts condition class by approximate acres of fire return interval departure.

Approximately 80 percent of the project area is moderately to severely departed from historic 

fire return intervals.

Figure B-1: Historical Reference Vonditions (Condition Class) Based Fire Return Interval Departure

0

2000

4000

6000

8000

10000

12000

14000

16000

I II III

Acres

Condition Class

Condition Class Based on Fire Return Interval 

Departure
Fire and Fuels Craggy Vegetation Management Project

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Appendix C – Fuels and Fuel Modeling

Fuels

To model and predict fire behavior, fuels are often broken into fuel models that are 

mathematically put into a fire spread calculation (Rothermel 1972). Geographic information 

system layers of the Landfire Landscape (i.e., fuel models derived from the vegetation layer) 

were obtained to analyze current fuel models within the project boundary. The fuel models (Scott 

and Burgan, 2005) within the project boundary are described in Table C-1.

Table C-1: Fuel Model Descriptions within the Project Area by Acres and Percentage of Area

Fuel Model 

Category Fuel Model Name Description Acres of fuel model 

in project area

Percent within 

project area

91, 97, 98, 99 Non-Flammable 

Fuel Models

Non-flammable. For example, open water, urban 

development, or bare ground 688 2%

101 – GR1, 

102 – GR2 Grass Fuel Models

The primary carrier for GR1 is sparse grass. The 

grass is generally short and may be sparse or 

discontinuous. Rates of spread and flame lengths 

are low. The primary carrier for GR2 is grass, 

though small amounts of fine dead material may be 

present. Load is greater than GR1, and fuelbed more 

continuous. Spread rates are high and flame lengths 

moderate.

242 <1%

121 – GS1, 

122 – GS2

Grass-Shrub Fuel 

Models

The primary carrier of fire in GS1 and GS 2 is grass 

and shrubs combined. Spread rate is high; flame 

length moderate.

6,260 21%

142 – SH2 Shrub Fuel Models

The primary carrier of fire in SH2 is woody shrubs 

and shrub litter. Moderate fuel load (higher than 

SH1), depth about 1 foot, no grass fuel present. 

Spread rate is moderate; flame length moderate.

2,877 9%

145 – SH5 Shrub Fuel Models

The primary carrier of fire in SH5 is woody shrubs 

and shrub litter. Heavy shrub load, depth 4-6 feet. 

Spread rate is very high; flame length very high.

2347 8%

147 – SH7 Shrub Fuel Models

The primary carrier of fire in SH7 is woody shrub 

litter. Very heavy shrub load, depth 4 to 6 feet. 

Spread rate is high; flame length very high.

6,230 21%

165 – TU5 Timber-Understory 

Fuel Models

The primary carrier of fire in TU5 is heavy forest 

litter with a shrub or small tree understory. Spread 

rate is moderate; flame length high.

5,232 18%

183 – TL3 Timber-Litter Fuel 

Models

The primary carrier of fire in TL3 is moderate load 

conifer litter, light load of coarse fuels. Spread rate 

is very low; flame length very low.

394 1%

186 – TL6 Timber-Litter Fuel 

Models

The primary carrier of fire in TL6 is moderate load 

broadleaf litter, less compact than TL2. Spread rate 

is moderate; flame length low.

252 1%

188 – TL8 Timber-Litter Fuel 

Models

The primary carrier of fire in TL8 is moderate load 

long-needle pine litter, may include small amount of 

herbaceous load. Spread rate is moderate; flame 

length low.

2,914 10%
Fire and Fuels Craggy Vegetation Management Project

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Fuel Model 

Category Fuel Model Name Description Acres of fuel model in project area

Percent within 

project area

189 – TL9 Timber-Litter Fuel 

Models

The primary carrier of fire in TL9 is very high load, 

fluffy broadleaf litter. TL9 can also be used to 

represent heavy needle-drape. Spread rate is 

moderate; flame length moderate.

1,593 5%

Other Other Fuel Models

Other fuel models within the analysis boundary less 

than 400 Acres and make up a small percentage of 

the total area.

687 2%

Descriptions based on Anderson 1982 and Scott and Burgan 2005. Fuel models derived from Landfire and clipped to the analysis area in GIS. 

Fire Risk

Fire risk is defined in the Forest Plan as the probability of a fire start occurring over a ten year 

period for a given thousand acre area. Fire risk is based on the Forest geographic information 

system layers for fire occurrence records within the analysis area. The risk classification within 

the Forest Plan is as follows:

• Low Risk = 0 to 0.49: Less than 0.5 fires expected to occur per decade for every thousand 

acres in the area being analyzed.

• Moderate Risk = 0.50 to 0.99: Between 0.5 and 0.99 fires expected to occur per decade 

for every thousand acres in the area being analyzed.

• High Risk = At least one fire expected to occur per decade for every thousand acres in the 

area being analyzed.

Within the project boundary (29,693 acres) 72 fire starts occurred over a 30-year period analyzed 

(1986 to 2015). The risk value formula is R = {(x/y) 10}/z 

Where:

x = fire starts (72)

y = period analyzed (30 years)

z = number of acres analyzed (29,693 displayed in thousands = 29.7)

Risk rating = {(72/30) 10}/29.7 = .80 (Moderate Risk)

The project area has a moderate fire risk value. The primary source of ignition (approximately 81 

percent) is lightning caused while approximately 19 percent was human caused ignitions.
Fire and Fuels Craggy Vegetation Management Project

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Appendix D – Wildland Urban Interface Zones within Craggy 

Project Area

Figure D-1: Wildland Urban Interface Zones within Craggy Project Area