U.S. Department of Agriculture

Pacific Northwest Research Station

333 SW First Avenue

P.O. Box 3890

Portland, OR 97208-3890

Official Business

Penalty for Private Use, $300
Authors

Morris C. Johnson is an ecologist and David L. Peterson is a research biologist, 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 

Pacific Wildland Fire Sciences Laboratory, 400 N 34th Street, Suite 201, Seattle, 

WA 98103; Crystal L. Raymond is a research scientist, College of Forest Resources, 

University of Washington, Box 352100, Seattle, WA 98195.

The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use 

management of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and 

recreation. Through forestry research, cooperation with the States and private forest owners, and 

management of the National Forests and National Grasslands, it strives—as directed by Congress—to 

provide increasingly greater service to a growing Nation.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities 

on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, 

familial status, parental status, religion, sexual orientation, genetic information, political beliefs, 

reprisal, or because all or part of an individual’s income is derived from any public assistance program. 

(Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative 

means for communication of program information (Braille, large print, audiotape, etc.) should contact 

USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write 

USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 20250-9410 

or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and 

employer.
Abstract

Johnson, Morris C.; Peterson, David L.; Raymond, Crystal L. 2007. Guide to 

fuel treatments in dry forests of the Western United States: assessing forest 

structure and fire hazard. Gen. Tech. Rep. PNW-GTR-686. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

322 p.

Guide to Fuel Treatments analyzes a range of fuel treatments for representative 

dry forest stands in the Western United States with overstories dominated by 

ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii), and pinyon 

pine (Pinus edulis). Six silvicultural options (no thinning; thinning from below 

to 50 trees per acre [tpa], 100 tpa, 200 tpa, and 300 tpa; and prescribed fire) are 

considered in combination with three surface fuel treatments (no treatment, pile 

and burn, and prescribed fire), resulting in a range of alternative treatments for 

each representative stand. The Fire and Fuels Extension of the Forest Vegetation 

Simulator (FFE-FVS) was used to calculate the immediate effects of treatments on 

surface fuels, fire hazard, potential fire behavior, and forest structure. The FFEFVS was also used to calculate a 50-year time series of treatment effects at 10-year 

increments. Usually, thinning to 50 to 100 tpa and an associated surface fuel 

treatment were shown to be necessary to alter potential fire behavior from crown 

fire to surface fire under severe fire weather conditions. This level of fuel treatment 

generally was predicted to maintain potential fire behavior as surface fire for 30 to 

40 years, depending on how fast regeneration occurs in the understory, after which 

additional fuel treatment would be necessary to maintain surface fire behavior. 

Fuel treatment scenarios presented here can be used by resource managers to 

examine alternatives for National Environmental Policy Act documents and other 

applications that require scientifically based information to quantify the effects of 

modifying forest structure and surface fuels. 

Keywords: Dry forest, FFE-FVS, fire, fire behavior, fire hazard, fuel treatments, 

silviculture.
Contents

	 1	 What Is Guide to Fuel Treatments in Dry Forests of the Western United States?

	 1	 Why Is Guide to Fuel Treatments Needed?

	 2	 How Was Guide to Fuel Treatments Developed?

	 3	 Which Data Are Used for Forest Stands, Fuels, and Fire Weather?

	 4	 How Is the Fire and Fuels Extension-Forest Vegetation Simulator (FFE-FVS) Used?

	 5	 Fuel Model Selection for Fire Behavior Calculations

	 8	 Limitations of FFE-FVS Simulations

	 8	 Which Fuel Treatment Scenarios Are Analyzed?

	 9	 Thinning

	 9	 Surface Fuel Treatments

	 10	 Tree Regeneration

	 12	 How Do I Use Guide to Fuel Treatments?

	 14	 Do Your Own FVS Runs

	 14	 How Is Output From the Guide Interpreted and Applied?

	 14	 An Example Scenario

	 16	 FFE-FVS Output and Expert Judgment

	 16	 Glossary

	 18	 Acknowledgments

	 18	 Metric Equivalents

	 19	 Literature Cited

	 21	 Appendix 1: Keywords Used in FFE-FVS for Simulations Represented in the Guide

	 23	 Appendix 2: Fuel Treatment Scenarios for the Northern Region (Region 1)

	 23	 Region 1—Bitterroot National Forest 1

	 35	 Region 1—Bitterroot National Forest 2

	 47	 Region 1—Gallatin National Forest

	 59	 Region 1—Lewis and Clark National Forest 1

	 71	 Region 1—Lewis and Clark National Forest 2

	 83	 Appendix 3: Fuel Treatment Scenarios for the Southwestern Region (Region 3)

	 83	 Region 3—Carson National Forest 1

	 95	 Region 3—Carson National Forest 2

	107	 Region 3—Kaibab National Forest

	119	 Region 3—Pinyon Woodland

	131	 Region 3—Santa Fe National Forest 1

	143	 Region 3—Santa Fe National Forest 2

	155	 Appendix 4: Fuel Treatment Scenarios for the Intermountain Region (Region 4)

	155	 Region 4—Payette National Forest 1

	167	 Region 4—Payette National Forest 2

	179	 Region 4—Payette National Forest 3

	191	 Appendix 5: Fuel Treatment Scenarios for the Pacific Southwest Region (Region 5)

	191	 Region 5—Plumas National Forest

	203	 Region 5—Sierra National Forest 1

	215	 Region 5—Sierra National Forest 2

	227	 Region 5—Sierra National Forest 3

	239	 Appendix 6: Fuel Treatment Scenarios for the Pacific Northwest Region (Region 6)

	239	 Region 6—Deschutes National Forest 1

	251	 Region 6—Deschutes National Forest 2

	263	 Region 6—Deschutes National Forest 3

	275	 Region 6—Malheur National Forest

	287	 Region 6—Okanogan and Wenatchee National Forests 1

	299	 Region 6—Okanogan and Wenatchee National Forests 2

	311	 Region 6—Okanogan and Wenatchee National Forests 3
What Is Guide to Fuel Treatments 

in Dry Forests of the Western 

United States?

Guide to Fuel Treatments analyzes potential fuel

treatments, and the potential effects of those treatments, for dry forest lands in the Western United

States. The Guide examines lower to mid-elevation

dry forest stands with high stem densities and

heavy ladder fuels, which are currently common

owing to fire exclusion and various land management practices such as timber harvest. These

stands are the focus of potential management

activities intended to modify forest structure and

fuels to reduce crown-fire hazard on public lands.

The Guide is intended for use by fire managers,

silviculturists, and other resource specialists who

are interested in evaluating the effects of fuel treatment on dry forest ecosystems.

The scientific basis for fuel treatments is documented in recent syntheses (Graham et al. 2004,

Peterson et al. 2005) and numerous publications

(Agee 1996, 2002; Brown et al. 2004; Carey and

Schuman 2003; Fitzgerald 2002; Kalabokidis

and Omi 1998; Keyes and O’Hara 2002; Pollet

and Omi 2002; Sandberg et al. 2001; Scott and

Reinhardt 2001; Weatherspoon 1996). The Guide

provides quantitative guidelines for treatments

based on the scientific principles in these documents and is intended to cover a broad range of

possible treatments and stand conditions. However, the representative cases in this publication

are not comprehensive, and interpretation and

application of quantitative output will typically

need to be adjusted based on local conditions and

objectives.

The effects of fuel treatments are quantified for

forest structure, surface fuels, and potential fire

behavior. The Fire and Fuels Extension—Forest

Vegetation Simulator (FFE-FVS) (Reinhardt and

Crookston 2003) was used to calculate a variety

of fuel treatment combinations (5 levels of thinning, 3 types of surface fuel modification; and

prescribed fire only) for each of 25 representative

forest stands. Output from FFE-FVS runs is

summarized for each stand with visualizations

and extensive tabular data. In addition, forest

structure and fuels are calculated for 50 years

posttreatment at 10-year increments, so that longterm stand conditions can be assessed and users

can determine when additional fuel treatments

might be needed. Users familiar with FFE-FVS

have the option of running their own simulations

to calculate site-specific effects of treatments.

Why Is Guide to Fuel Treatments

Needed?

Federal agencies in the United States have a

strong policy and management focus on reduction

of fuels that have accumulated in dry forest

ecosystems from which fire has been excluded

for up to a century. For example, the Healthy

Forests Restoration Act (2003) provides affirmative

direction for increased fuel treatments to reduce

accumulated fuels and reduce the risk of large

and severe fires, especially in the wildlandurban interface and municipal watersheds. As

federal agencies and other institutions begin to

increase the amount of land area subjected to fuel

treatments, they will need quantitative guidelines

to develop alternatives for achieving desired future

conditions. These alternatives need to consider

options for silvicultural manipulation (thinning)


of stands, as well as surface fuel treatments. The

temporal effectiveness of fuel treatments also needs

to be quantified, so that additional treatments can

be considered in long-term planning.

Science-based rationale and quantitative

guidelines are especially needed for regulatory

documentation associated with fuel management

and planning. The National Environmental

Policy Act (NEPA) requires that alternatives be

considered in the development of environmental

impact statements, environmental assessments,

and associated documentation. These alternatives

typically contain qualitative and quantitative

descriptions of proposed management actions for

a particular forest stand or landscape. The Guide

displays potential outcomes of applying alternative

combinations of fuel treatments—namely,

removal of tree stems (thinning) and reduction

in surface fuels (surface fuel treatment)—and

facilitates quantitative analysis and review of the

alternatives in terms of forest stand attributes,

fuels, and potential fire behavior. The availability

of visualizations and tabular data in a standard

format allows resource managers to examine

and select preferred fuel treatment alternatives.

Visualizations are particularly useful for

displaying the outcome of fuel treatment options

to stakeholders and the general public who do not

have formal training in natural resources.

How Was Guide to Fuel 

Treatments Developed?

The Guide was developed by scientists at the

Pacific Wildland Fire Sciences Laboratory, Pacific

Northwest Research Station, in cooperation with

other scientists and resource managers throughout

the Western United States. The central concept is

to link information and data from silviculture and

fire science to (1) assist decisionmaking about fuel

treatments in dry forest stands and (2) provide

quantitative guidelines for fuel treatment that

allow consideration of desired future conditions

for multiple resources (e.g., wildlife, water, timber

production). Final structure of the Guide was

determined after reviews by scientists and resource

managers, and two tests with national forests.

The FFE-FVS (Reinhardt and Crookston 2003)

was used to prepare the Guide. This tool links

forest growth modeling (FVS) with fire behavior

modeling (FFE) to produce information relevant

to management of forest stands, fuels, and fire.

FVS has been widely used by resource managers

and scientists for over two decades, has been

programmed to cover many of the major forest

types in the United States, and is regarded as a

credible tool for applications in forest management. Integration of fire concepts is a recent and

valuable extension of the FVS approach to forest

stand simulation, and has not been available long

enough to be thoroughly tested. However, it is the

only analytical tool currently available that quantitatively links stand dynamics and fire science.

At a minimum, FFE-FVS requires input of forest

stand attribute data (species, diameter at breast

height [d.b.h.], and height), although fuels data

are extremely helpful.

Scenarios displayed in the Guide are intended

to represent a range of dry forest types in the

Western United States, specifically those forests

dominated by ponderosa pine (Pinus ponderosa

Dougl. ex Laws), mixed conifer (often including

Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]

as a codominant), and pinyon-juniper (Pinus spp.,

Juniperus spp.). Specific stand data were obtained
from resource managers on national forest units

throughout the Western United States. Stands

selected for analysis had high stem densities, and

had not experienced recent fire or thinning. In the

Guide, only stands at relatively low elevations and

slopes <40 percent were considered as potential

candidates for fuel treatment. Fuel treatment

scenarios are organized according to Forest Service

regions in the Western United States.

Which Data Are Used for Forest 

Stands, Fuels, and Fire Weather?

Field Sampled Vegetation (FSVeg) is an Oracle

1

database used to store data on overstory

trees from grid-based strategic inventories,

permanent remeasured inventory plots, and stand

examinations. Data were obtained for ponderosa

pine, mixed conifer, and pinyon-juniper forests

in the FSVeg database from national forests in

the Northern Region (Region 1), Southwestern

Region (Region 3), Intermountain Region (Region

4), Pacific Southwest Region (Region 5), and

Pacific Northwest Region (Region 6); we were

unable to obtain usable data from the Rocky

Mountain Region (Region 2). Two scenarios for

pinyon-juniper were derived from Forest Inventory

and Analysis (FIA) data. The FSVeg data were

converted to files that could be loaded directly into

FVS. Data from 37,734 stands were obtained and

screened for selection of stands to be used in fuel

treatment scenarios.

Default values are provided in FFE-FVS for initial

surface fuel loadings. Although actual fuels data

can be entered, those data are converted to stylized

fuel models (Anderson 1982), which are then used

for fire behavior calculations; the original fuel

values are not used. There are only 14 fuel models,

onlya few of which are generally used for forest

fuels, although an option within FFE-FVS can be

selected to use mixtures of fuel models to approxi

-

mate conditions that are not well represented

by an individual fuel model. Decision rules in

FFE-FVS assign fuel loadings based on dominant

cover type and percentage of cover. The rules and

values used to estimate default initial fuel loads by

size class differ between FVS variants.

The FFE-FVS model allows users to specify

moisture percentage for woody surface fuels

(1-, 10-, 100-, 1,000- and >1,000-hr, or 0–1⁄4,

1⁄4–1, 1–3, 3–6, and >6 in diameter, respectively;

see glossary), duff, and live vegetation. Default

values for live and duff fuel moisture for each

variant were used. Twenty-foot windspeed and

temperature can also be adjusted. The 20-foot

windspeed isa 10-minute average windspeed

20 feet above the ground.

The 75th and 98th percentile historical fire weather

data from each geographic area were obtained

from the USDA Forest Service Predictive Service

Division and the Western Regional Climate Center

(Reno, Nevada). Remote automated weather

stations (RAWS) located near each national forest

were identified by using geographic information

system coverages of federal land ownership and

latitude/longitude coordinates for all hourly RAWS

data archived at the Western Regional Climate

Center. We used historical data from the fire

season only (typically April to September, although

this can vary) for fire behavior predictions. The

75th and 98th percentiles represent conditions at

1 The use of trade or firm names in this publication is for 

reader information and does not imply endorsement by the 

U.S. Department of Agriculture of any product or service.
the extreme of the range of values for temperature

(high), relative humidity (low), windspeed (high),

and fuel moisture (low) that facilitate fuel flammability and fire spread. These percentiles are

commonly used in NEPA assessments involving

fire, and slight variations of these percentiles are

used for various applications in fire management

and planning. For convenience, they are referred

to in the Guide as moderate (75th) and severe

(98th) fire weather.

A coarse quality control evaluation of the RAWS

data was conducted similar to that described

in Brown et al. (2002). The program removed

erroneous data and physically unreasonable

values (e.g., negative windspeed). Data used in the

percentile calculations of fire weather were for the

period between 1985 and 2004. The 100-hr fuel

moistures were derived through scaling by adding

3 percent to the 10-hr fuel moistures from the

RAWS data; this closely matches what is observed

in the field.2 Windspeeds were adjusted by using

a wind gusting estimation table (Crosby and

Chandler 2004).

How Is the Fire and Fuels 

Extension—Forest Vegetation 

Simulator (FFE-FVS) Used?

The Forest Vegetation Simulator (FVS) is an

individual-tree growth and yield model for major

forest tree species, forest types, and stand conditions (Dixon 2002). Variants of FVS are available

for specific areas of the United States (fig. 1). Variants are versions of simulated growth and yield

customized for species and productivities in forest

ecosystems. The FVS variants for the Intermountain and Northern Rocky Mountain regions are

generally considered more accurate than other

variants, and have more detailed options, because

FVS has been developed and used at these locations much longer than at other locations.

The FVS is a deterministic model, and for a

given set of inputs will always calculate the same

outputs. This contrasts with stochastic models

that can introduce variability into calculations

and thereby derive multiple outputs for the same

set of inputs. Resource managers also need to consider ecological disturbances such as fire, insects,

windthrow, and fungal pathogens as potential

sources of variability within the fixed time series

of FVS outputs.

First, forest stand structure and composition data

(also called an FVS portfolio) were developed for

each national forest by using the FVS-ready files,

historical fire weather data, and default surface

fuel loadings. A complete list of FVS “keywords”

used initially to build the portfolios is listed in

appendix 1; these keywords are used to select

specific assumptions and options for growth and

yield simulation. The portfolio was projected 50

years to observe potential fire behavior under

moderate and severe weather scenarios. Each stand

was visualized in Stand Visualization Software

(SVS) and converted to EnVision images to observe

the horizontal and vertical distribution of stand

structure, canopy fuels, and subcanopy fuels. For

each candidate stand, 14 FFE-FVS key files were

developed according to the treatment options

summarized in figure 2.

2Agee, James. 2003. Personal communication. Fire ecologist, 

University of Washington. 
Figure 1—Geographic variants of the Forest Vegetation Simulator. These variants account for tree growth rates and 

structures associated with specific geographic locations, and are described in detail in Dixon (2002).

The Guide displays treatment effects on stand

structure, surface fuel loading, and potential fire

behavior. The potential fire behavior report is

generated for moderate and severe fire weather

scenarios, and provides information about

expected fire type, flame length, crown fire

potential, and tree mortality, given the weather

and stand structure conditions. Different

treatments can then be compared with respect

to desired future conditions for specific

management objectives.

Fuel Model Selection for 

Fire Behavior Calculations

Fire behavior calculations in FFE-FVS depend on

stylized fuel models (Anderson 1982) rather than

actual fuels. When silvicultural treatments are

implemented in FFE-FVS, the actual activity fuel

or slash created is not used to estimate potential

fire behavior. The FFE-FVS model has the capacity

to simulate and track fuel loadings by size class

over time, although it does not use the loadings

directly as inputs for calculating fire behavior.

Instead, FFE uses the loadings and other stand


Figure 2—Conceptual diagram of the process used to simulate the effects of fuel treatments for a forest stand in FFE-FVS. 

Note: tpa = trees per acre; d.b.h.= diameter at breast height.

Thin from

below to 50

tpa, 18-in

d.b.h. limit

Prescribed

fire only

No action Thin from

below to

100 tpa,

18-in d.b.h.

limit

Thin from

below to

200 tpa,

18-in d.b.h.

limit

Thin from

below to

300 tpa,

18-in d.b.h.

limit

No action Pile and burn Prescribed fire


characteristics to select one or more models from

14 fuel models. The rules used to select fuel

models differ among geographic variants.

Each fuel model represents homogeneous surface

fuel conditions in which fire behavior is considered to respond similarly to changes in fuel

moisture, wind, and slope. The models define

values for several parameters difficult to measure

in the stand and that are not tracked in FFE,

including fuel surface-to-volume ratio, loading,

depth, moisture of extinction, heat of combustion,

dry density, total mineral content, and silica-free

mineral content.

The “dynamic option” in FFE that we used in

simulations to produce the Guide selects one or

more fuel models based on fuel loadings and other

stand characteristics, calculates fire intensity

from each one, then computes a weighted average

flame length by interpolating factors such as fuel

loading or canopy cover. This approach can use

several fuel models, weighted by percentage of

each fuel model, and calculates flame lengths that

change more gradually as stand conditions change

than those computed from a “static” approach

with a single fuel model. It partially addresses the

concern about using single fuel models to represent large, complex fuelbeds. Based on feedback

we obtained from resource managers, we feel that

the dynamic option provides more accurate output

for Intermountain and Northern Rocky Mountain

forests than for locations where other FVS variants

were used.

Once a fuel model is selected, its parameters are

used to estimate potential fire behavior (Reinhardt

and Crookston 2003). Using fuel models rather

than actual fuel quantities reduces the accuracy

with which fuels are represented in the simulation

process. Because of the limited number of fuel

models, the same fuel model may be used for very

different fuelbeds, resulting in no difference in

predicted fire behavior.

There are common situations for which FFE-FVS

may produce unrealistic predictions of potential

fire behavior. For example, fuels can be removed

through thinning or surface fuel treatment without

a commensurate change in fuel models and potential fire behavior. Another unrealistic situation

occurs as fuels accumulate through time such that

a threshold is exceeded and another fuel model

is selected, leading to a sudden, large change in

fire behavior with only a small change in fuel

conditions. A more reasonable result is a gradual

change in predicted fire behavior corresponding

to gradual changes in fuels. Finally, fuel model

2, a grass-dominated fuel model, is sometimes

selected after heavy thinning (to 50 to 100 trees

per acre [tpa]); this model results in higher flame

lengths and increased crown fire potential, which

is typically unlikely, especially if surface fuels have

also been treated.

For all variants, different selection logic is used for

natural fuels than for activity fuels (fuels resulting

from harvest within the last 5 years), and for high

and low loadings of woody fuel. All variants use

the same logic for activity fuels and when woody

debris is abundant. In these cases, the fuel model

depends only on the amount of small (<3 in) and

large (>3 in) fuel in the stand, and whether the fuel

is natural or activity.


Limitations of FFE-FVS Simulations

The FVS model simulates growth and mortality

typically using cycles of 10 years, whereas FFE

operates on a 1-year cycle. This can lead to model

behavior that is an artifact of combining the two

time steps, and is not intended to represent a real

phenomenon (Reinhardt and Crookston 2003).

For example, snag numbers tend to exhibit a

saw-toothed pattern, with sharp increases at cycle

boundaries when all the cycle’s natural mortality is added, and gradual declines between cycle

boundaries as snag fall-down occurs. Choosing

short cycle lengths or reporting indicators only at

cycle boundaries can somewhat compensate for

this problem.

Discontinuous behavior is particularly evident

in indicators that depend in part on canopy

base height: canopy base height itself, torching

index, potential tree mortality, and fire type. For

example, regeneration often occurs in pulses, and

a stand passes a critical point after which vulnerability to torching sharply increases or decreases.

These discontinuities are probably exaggerated

by the fact that regeneration and mortality occur

on cycle boundaries in the model. Self-pruning of

large trees and mortality of understory trees may

cause canopy base height to increase sharply at a

cycle boundary, or understory regeneration may

cause the canopy base height to decrease abruptly

(Reinhardt and Crookston 2003).

Live fuels (herbaceous plants and shrubs) are

poorly represented in FFE-FVS. Their biomass and

contribution to fuel consumption and smoke are

only nominally represented as a fixed amount that

depends on percentage of cover and dominant tree

species. Live fuels can contribute significantly to

fire behavior in many forest systems, but they are

represented only by how fuel models are selected

rather than by what is really present in a stand.

For example, some shrubs regenerate quickly after

thinning and prescribed fire, but shrub regeneration, growth, and fuels are not explicitly simulated

in FFE-FVS. Therefore, users need to adjust

simulation output to account for shrub fuels and

their role in fire behavior.

Canopy cover, overstory composition, habitat

type, and stand history influence selection of fuel

models. Live fuels are not dynamically tracked and

simulated in FFE-FVS. The default decomposition rate is often inaccurate, generally resulting in

higher rates of decomposition and loss of organic

matter than is realistic for most forest systems, and

unrealistic transfer rates between litter and duff.

The default decomposition rate is not sensitive to

aspect, elevation, or potential vegetation type in

FFE-FVS. Experienced FFE-FVS users can adjust

these rates to more accurately reflect processes

within specific forest stands.

Which Fuel Treatment Scenarios 

Are Analyzed?

Fuel treatment scenarios analyzed in Guide to 

Fuel Treatments were determined with extensive

feedback from federal resource managers. These

scenarios cover a range of potential thinning and

surface fuel treatments that would be reasonable

and appropriate alternatives for NEPA analysis and

similar documentation. The scenarios are intended

to illustrate representative situations that might be

encountered in operational management and planning, and do not illustrate all possible treatments.
Thinning

The following thinning options are considered:

•	 No thinning

•	 Thinning from below to 50 tpa

•	 Thinning from below to 100 tpa

•	 Thinning from below to 200 tpa

•	 Thinning from below to 300 tpa

•	 Prescribed fire only

Thinning from below (or low thinning) refers

to removal of stems starting from smallest to

increasingly larger stems until the target density

is reached. In practice, thinning from below

often has a d.b.h. limit below which no stems

are harvested, with that lower limit set to reduce

costs and maximize value of harvested material.

In Guide scenarios, all stems are harvested

starting with trees smaller than 1 in d.b.h., then

proceeding to larger stems. For all thinnings,

no trees larger than 18 in d.b.h. are allowed to

be harvested. This limit is intended to retain

larger, more fire-resistant individuals. In practice,

this upper d.b.h. limit could be higher or lower

depending on local harvest specifications and

resource objectives.

Thinning from below is the most commonly used

approach to modify stand structure, density,

and fuels, although many other silvicultural

approaches are available (Graham et al. 1999).

Thinning as used within FVS is applied equally

across a given stand. In practice, variable-density

thinning—a spatial pattern of tree clumps and

openings—can be used to achieve the same final

tree density but attain greater heterogeneity in

stand structure. Variable-density thinning cannot

be represented in FVS, and is therefore not

considered here.

For target densities different than those in the

Guide, users can interpolate or extrapolate the

results found in tables and visualizations. Exploratory runs of FFE-FVS indicate that thinning to 

densities greater than 300 tpa rarely changes 

fuel conditions enough to modify fire hazard

significantly from initial stand conditions.

Some managers prefer to use basal area as a target

for thinning. This measurement may be more

appropriate for even-aged stands with relatively

low variability in tree size. Basal area is calculated

for each thinning treatment, so both basal area

and stem density are available for all scenarios.

Surface Fuel Treatments

The following fuel treatment options are considered for all types of stands (table 1):

•	 No surface fuel treatment

•	 Pile and burn

•	 Prescribed fire

In practice, techniques used for modification

of activity fuels and residual surface fuels vary

considerably, as does the effectiveness of those

techniques. Options included in the Guide are

intended to capture the more common approaches

currently used in the field, and to represent moderately high effectiveness. Assumptions regarding

slash disposal, material left on site, area affected,

and effectiveness of treatments are summarized in

table 1. Prescribed fire is considered to be a broadcast burn that covers the entire treatment area.

The assumptions in table 1 can be quite important

with respect to fuel characteristics and potential

fire behavior after treatments. For example, the

effectiveness of prescribed fire varies greatly in
10

terms of quantity and sizes of fuels removed.

Users need to consider how variation in surface

fuel treatment might affect the output tables for

scenarios presented here. Experienced FVS users

can modify fuel treatment options in terms of both

technique and effectiveness to more accurately

represent specific treatments.

Successful use of prescribed fire as the only fuel

treatment can be challenging in stands with dense

ladder fuels and high loadings of surface fuel.

However, prescribed fire is sometimes used as the

only method of fuel treatment in mixed-conifer

forest of the Sierra Nevada, typically with successive burns 5 to 10 years apart. We examined the

case of two successive burns for the three Sierra

Nevada mixed-conifer stand examples in the Guide

and found that an additional prescribed burn

conducted 10 years later reduced surface loadings

and surface flame height. The effects from the

second prescribed burn also increased torching

index, tree mortality, and canopy base height.

However, we have not included the two-burn case

in the scenarios because it is not widely used in

Western dry forests and is considered too risky by

some resource managers.

Tree Regeneration

Regeneration in FFE-FVS can affect stand

structure and potential fire behavior through its

influence on canopy base height and canopy bulk

density, so careful attention is necessary when

simulating regeneration. The FVS model includes

two regeneration models: (1) a full establishment

model that automatically simulates input and

growth of regeneration after tree removal, and

(2) a partial establishment model that requires

user input for stocking (portion of area that

contains at least one seedling), density, and size

of regeneration.

The full establishment model was used for the

national forests for which it was available: Payette,

Bitterroot, Lewis and Clark, and Gallatin National

Forests. The model automatically predicts natural

regeneration when thinning removes >30 percent

Table 1—Summary of values and assumptions used in FFE-FVS for surface fuel treatments

Surface fuel treatment FFE-FVS values and assumptions FVS keywords

No action All boles greater than 6 in diameter at breast height (d.b.h.) are removed Yardloss

from stand. The entire tree (branch and bole) and branch material from 

trees greater than 6 in d.b.h. are left in stand.

Pile and burn All boles greater than 6 in d.b.h. are removed from stand. The entire Yardloss

tree (branch and bole) and branch material from trees greater than PileBurn

 6 in d.b.h. are left in stand. 80% of the remaining fuel from the entire 

stand is concentrated into piles that cover 10% of the stand area. 

No tree mortality will result. 

Prescribed fire All boles greater than 6 in d.b.h. are removed from stand. The entire tree Yardloss

(branch and bole) and branch material from trees greater than 6 in d.b.h. SimFire

are left in stand. Windspeed at 20 ft above vegetation = 10 mph. FVS 

predefined moisture group (3) selected to represent fuel moisture 

percentages for prescribed fires. Temperature equals 70 °F. Note: 

predefined moisture values are specific to FVS variants. 
11

of trees in the stand, and then adds this regeneration to the tree list for growth simulation. FVS

predicts stocking level, density, and species composition of regeneration by using several variables

including geographic location, topography, habitat

type, and basal area and species composition of

residual overstory (Ferguson and Crookston 1991).

Regeneration can be added incrementally for up

to 20 years after thinning, or in one pulse immediately after thinning. We used the latter option,

and regeneration was restricted to one pulse 5

years after thinning. Site preparation (scarification

and prescribed burning) increases mineral soil

exposure enabling more regeneration (Sackett

1984), so we increased stocking area for the pile

and burn (1.5 times) and prescribed fire (2 times)

surface fuel treatments to simulate this effect.

A combination of scientific literature, unpublished

data, and expert knowledge of local managers

was used to determine region-specific values for

regeneration where the full establishment model

was not available, and these values were adjusted

based on expected trends associated with residual

overstory density and surface fuel treatments

(table 2). Regeneration after thinning is variable

and depends on the residual overstory and site

quality of the stand, as well as seed availability

and soil moisture in the years after treatment

(Bailey and Covington 2002, Sackett 1984).

Therefore, values used in the Guide are estimates

and should be adjusted based on local conditions

when information is available. The more a stand

is opened by thinning, the more growing space is

available for regeneration (Bailey and Covington

2002, McDonald 1976). We used this general

relationship to estimate regeneration in the 100

tpa thinning as half that of the 50 tpa thinning,

and regeneration in the 200 tpa and 300 tpa

thinning as half that of the 100 tpa thinning

(table 2). These values were then adjusted for the

surface fuel treatment options; regeneration in the

pile and burn is 1.5 times that of the no surface

fuel treatment option, and regeneration in the

prescribed fire is 3 times that of the no surface

fuel treatment option.

Table 2—Number of trees used for regeneration in the partial establishment model of FVS

FVS-simulated Surface fuel treatment

Forest Service Region thinning treatment None Pile and burn Prescribed fire

Trees per acre

Region 3 50 15 23 45

100 8 12 25

200 4 6 12

300 4 6 12

Region 5 50 50 75 150

100 25 38 75

200 13 20 40

300 13 20 40

Region 6 50 100 150 300

100 50 75 150

200 25 38 75

300 25 38 75
12

How Do I Use Guide to 

Fuel Treatments?

Output for each scenario in the Guide is

organized as follows:

•	 Page A—Initial stand conditions, including

a stand visualization for 1 acre.

•	 Page B—Visualizations for four thinning

treatments without surface fuel treatments for

1 acre. Surface fuel treatments cannot be shown

in images produced by FVS.

•	 Page C—Narrative describing highlights of

FFE-FVS output for different fuel-treatment

alternatives.

•	 Page D—Fuel, fire behavior, and fire effects

(percentage basal area mortality) for all possible

combinations of thinning and surface fuel

treatments, immediately after treatments.

•	 Pages E, F, G, and H—Fuel, fire behavior, and

snags for all treatments for 1, 10, 20, 30, 40,

and 50 years after treatment.

•	 Pages H, I, and J—Forest stand attributes for

all treatments 1, 10, 20, 30, 40, and 50 years

after treatment.

•	 Pages K and L—Summary of fire behavior fuel

models assigned by FFE-FVS for all possible

combinations of thinning and surface fuel

treatments for 1, 10, 20, 30, 40, and 50 years

after treatments.

•	 Page L—Summary of fire weather values

used in simulations for moderate and severe

conditions; limits used for prescribed fire.

The following describes a step-by-step 

approach to analyzing a scenario:

Step 1—

After you read and understand the material above,

identify the region where your stand is located.

For example, if you are working on the OkanoganWenatchee National Forests, you should look

in the section for the Pacific Northwest Region

(Region 6). Figure 1 shows the geographic distribution of FVS variants used for each scenario. You

may occasionally find that other Regions contain

scenarios that you consider to be more appropriate

for a particular situation.

Step 2—

Review the fuel treatment scenarios under the

appropriate appendix and find the initial stand

conditions (page A) and initial fuel conditions

(page D) that best match the stand (or broader

landscape) in which you are interested. You

will rarely find a perfect match, and may need

to mentally extrapolate Guide stand conditions

to your situation. For example, grand fir (Abies 

grandis (Dougl. ex D. Don) Lindl.) may be the

understory dominant in a Guide scenario, but

white fir (A. concolor (Gord. & Glend.) Lindl.)

is the understory dominant in your stand. The

difference in the effects of a given fuel treatment

owing to understory species will probably not be

large, because the basic principles of how fuels and

forest structure affect fire behavior drive FFE-FVS

calculations. Local knowledge should always guide

interpretation of this type of situation.
13

Step 3—

Decide which silvicultural option(s) you want to

consider: no thinning, thinning to 50 tpa, thinning to 100 tpa, thinning to 200 tpa, or thinning

to 300 tpa. Find the appropriate visualization

(page B) and compare it to initial stand conditions.

Step 4—

Decide which surface fuel treatments you want to

consider: no surface fuel treatment, pile and burn,

or prescribed fire.

Step 5—

The extensive tabular data for each scenario may

be difficult for inexperienced users to navigate,

and even experienced users can miss important

points. Therefore, narrative page C summaries are

provided that highlight critical outputs of the FFEFVS simulations that may be particularly helpful

in evaluating alternative fuel treatments

in the pages that follow.

Step 6—

Determine immediate effects of fuel treatments

on fuels, fire, and fire effects (percentage basal

area mortality) (page D). Thinning treatments are

listed across the top of the table, and surface fuel

treatments are listed down the left side.

Step 7—

Determine long-term effects of fuel treatments on

fuels, fire, and fire effects (pages E through H).

Silvicultural options (including both with and

without prescribed fire) are listed across the top

of the table, and surface fuel treatments are listed

down the left side for 1, 10, 20, 30, 40, and 50

years after treatment. By moving across the table

from left to right, you can observe how fuel loadings change through time, as well as how type of

fire changes. This information can help determine

when subsequent fuel treatment might be needed.

Step 8—

Determine long-term effects of fuel treatments

and silvicultural options on forest stand attributes

(pages H through J). Interpretations are similar to

those in Step 6 but with projections for 1, 10, 20,

30, 40, and 50 years after treatment. Information

on snags may be helpful for evaluation of wildlife

habitat. A guideline often applied in the field is

that canopy base height should be considerably

higher than potential flame length to reduce

crown fire hazard—compare canopy base height 

(pages H through J) to flame length (pages E 

through H) to evaluate crown fire potential.

Step 9—

Determine the long-term effects of thinning

options and surface fuel treatments on forest stand

attributes 1, 10, 20, 30, 40, and 50 years after

thinning (pages H through J). By moving across

the table from left to right, you can observe how

stand density and structure change over time.

This may affect decisions about subsequent

thinning, commercial harvest, and wildlife habitat.

Note that canopy base height is a particularly

important feature of canopy fuels that affects the

potential for fire to propagate from surface fuels

into the canopy.

Step 10—

Determine how fuel model assignment within

FFE-FVS varies through time for fuel treatment

alternatives; fuel model and relative weight are

given (pages K and L). This information allows

users to determine if appropriate fuel models

have been assigned. In addition, fire weather data
14

used in the FFE-FVS simulation are summarized

in two small, separate tables (page L). These data

provide a quantitative context for “moderate” and

“severe” weather conditions. If you prefer to use

other weather conditions, you can extrapolate or

interpolate as needed.

Do Your Own FVS Runs

Fuel treatment scenarios in the Guide illustrate

how silviculture and fire can be integrated. An

increasing number of resource managers are using

FVS as an analytical tool for assessing alternative management options. Current and potential

FFE-FVS users who want to run their own

simulations are encouraged to use the Guide as a

basis for screening potential management options.

Users may wish to run simulations on their own

FVS-ready files. The benefits of doing your own

FFE-FVS runs include generating output more

specific to a particular location, and the ability to

run FVS options other than the ones used here.

How Is Output From the Guide

Interpreted and Applied? 

An Example Scenario 

The step-by-step approach described above is

used here to illustrate how to interpret output

for a specific scenario in the Guide: Region 

6—Deschutes National Forest 1. In this

example, we assume the management objective is

to make the stand as resilient to fire as possible

by reducing crown fire hazard while maintaining

good forage for deer and elk. For this example,

assume that pile and burn is the preferred surface

fuel treatment.

Step 1—

The Deschutes National Forest is in Region 6, so

that section (Deschutes National Forest 1) of the

Guide (pages 239–250) should be consulted.

Step 2—

The stand has high stem density of 1,345 tpa

owing to fire exclusion, with a dense understory of

white fir creating ladder fuels into the ponderosa

pine overstory. The basal area of 246 ft2/ac is

relatively high, indicating potential for wood production, and for large trees and snags for wildlife

habitat (page 239). Surface fuel loadings are very

high, with 11 tons/ac for fuels <6 in diameter,

and very high duff loading of 20 tons/ac (page

242); this is typical of forests with a long period of

fire exclusion. These conditions are conducive to

high-intensity surface fire with the potential for

crown fire.

Step 3—

Thinning to 50 tpa or 100 tpa (page 240) appears

visually to be the only treatments that would

reduce ladder fuels sufficiently to reduce crown

fire hazard. Canopy base height (4 ft) (page 246)

needs to be raised considerably above the predicted flame length of the initial stand condition

(5 ft for severe weather) (page 242). Retention of

large ponderosa pine helps meet this objective,

because the high crowns avoid surface fire and

moderate crown fire, and the thick bark resists

surface fire.

Step 4—

The narrative summary (page 241) can help to

interpret important aspects of the simulation

output. All thinning treatments effectively reduce

canopy bulk density and increase canopy base
15

height enough to reduce crown fire potential; the

greater the thinning, the greater the reduction in

fire hazard. Thinning without surface fuel treatments increases surface fuel; the greater the thinning, the greater are activity fuels and potential

flame lengths.

Step 5—

Pile and burn (starting on page 242) will be used

to treat surface fuels, as noted above.

Step 6—

First, note that if fire were to occur in the stand

without any treatment, it would start a crown fire

(flame length of 4 or 5 ft on page 242 and canopy

base height of 4 ft on page 246). Thinning to 50 or

100 tpa with pile and burn confers considerable

fire resilience on the stand. Surface fuel treatment

(pile and burn) for the 50 tpa thinning greatly

reduces surface fuels <6 in diameter to 5 tons/ac

(page 242), or about half of the initial total (page

242), even though the thinning created activity

fuels from slash. Predicted flame length of 5 ft

(page 242) is well below the new canopy base

height of 44 ft (page 247); therefore fire behavior

changes from crown fire to surface fire, with negligible basal area mortality following all treatments.

Step 7—

We now examine the long-term effects of pile and

burn fuel treatments (pages 243 through 248). The

potential for crown fire remains low for 30 to 40

years. However, as surface fuels increase over time,

canopy base height decreases owing to growth

of small regenerating trees, canopy bulk density

increases, and the potential for crown fire returns.

Note that crown fire potential increases as flame

length (page 244) and canopy base height (page

247) become more similar. For this example stand,

thinning to 50 tpa and to 100 tpa appear to have

similar long-term effects on fuels and fire.

Step 8—

We may want to consider how an initial prescribed burn would compare to our preferred

fuel treatment options (page 242, 247). In this

case, a “successful” prescribed burn would have

reduced surface fuels, and removed most of the

small white fir and some ponderosa pine while

retaining only the largest overstory ponderosa

pine. Canopy base height remains well above

flame length for 30 years of the simulation,

thereby reducing long-term crown fire hazard.

Conclusions—

The above information indicates that thinning

to either 50 tpa or 100 tpa with surface fuel

treatment would meet the objective of reducing

crown fire hazard (page 247). However, this

reduction will last for 40 years in the 50 tpa

thinning versus 50 years in the 100 tpa thinning.

The 100 tpa thinning has the benefit of more

snags and cover, which could benefit certain

types of wildlife. It is important to remember the

recruitment of herbaceous vegetation and shrubs

is not simulated in FVS. Therefore, additional

thinning and/or surface fuel treatment would be

needed after 30 to 50 years to maintain a fireresilient condition. The option of using prescribed

fire as the only fuel treatment appears attractive.

However, considerable risk and planning are

involved in implementing a prescribed burn,

particularly in a dense stand where protection of

large trees is a priority, and an effective burn is

subject to weather and fuel conditions. As with any

fuel treatment, all relevant resources, including
16

posttreatment hydrology, social concerns, and

smoke production, should be included in the

decisionmaking process.

FFE-FVS Output and 

Expert Judgment

The Guide is intended to inform decisions—not 

make decisions. It is generally inappropriate

for users to directly apply information from the

Guide to management and planning issues. In fact,

doing so could sometimes cause significant errors,

owing to shortcomings of the modeling approach

described above, and differences between example

scenarios and local stand conditions. Most of

the numbers in the tables should be considered

“fuzzy” or to be an estimated mean with a range of

possible values.

Simulation models like FFE-FVS attempt to

mathematically represent complex interactions for

which thorough understanding and adequate data

do not exist. This is a challenging objective, and

it is often more realistic to compare the relative

magnitude of output among fuel treatment 

options or between time periods, than to 

compare the actual magnitude of output. Using

multiple parameters, rather than a single one, is

generally more appropriate for making decisions

about the effectiveness of a particular fuel treatment. Identifying patterns and trends of outputs

can be more valuable than focusing on individual

numbers in the tables.

The value of different components of the Guide

will differ depending on the application. For

example, a fuels specialist developing a long-term

plan may be particularly interested in the change

in fuel loadings over time. A wildlife specialist may

be interested in snags and large surface fuels. A

public information specialist may find the images

to be a useful component for presentation at local

stakeholder meetings. All applications of Guide

information should include some communication about the positive and negative aspects of

the simulation approach. Finally, the knowledge 

of local resource specialists in fire and fuels 

management is always required to interpret and 

apply the output of simulation models.

Glossary

active crown fire—A fire that moves as one

continuous flame front involving both canopy

fuels and surface fuels. If both torching index

and crowning index are less than the windspeed

measured 20 ft above the ground, fire type is

active crown fire.

activity fuel—Combustible material resulting

from or altered by forestry practices such as

thinning.

basal area—Cross-sectional area of all stems in

the stand measured at breast height expressed

per unit of land area (reported in English units as

ft2/ac).

canopy cover—FVS defines canopy cover as the

percentage of the ground area that is directly

covered by tree crowns.

canopy base height—Lowest height (ft) above

the ground at which sufficient canopy fuels are

available to propagate fire vertically through the

canopy. FFE defines “sufficient fuels” as at least 30

lb ac-1 ft-1 of available canopy fuels expressed as a

running 3-ft mean of available canopy fuels.
17

canopy bulk density—The available canopy fuel

load (foliage and 50 percent of branches <0.25 in),

calculated as the maximum 15-ft-deep running

mean for canopy layers 1 ft thick; reported by

convention in metric units (kg/m3) (see Scott and

Reinhardt [2001] for a more detailed description).

conditional crown fire—The type of fire observed

in the stand depends on the origin of the fire; a

surface fire will remain a surface fire when moving into the subject stand, and a crown fire will

remain a crown fire. If the crowning index is less

than the 20-ft windspeed but the torching index

is not, then the fire type is conditional crown fire.

Conditional crown fire is possible, but is a rare

event. (see Scott and Reinhardt [2001] for a more

detailed description).

crown competition factor—Relative measurement of stand density based on tree diameter. The

percentage of an acre that would be covered by

an individual tree’s crown if it were open grown

is calculated for each tree, and then the crown

competition factors for all trees are summed to get

the crown competition factor for the entire stand.

crown fire—A fire that burns in the elevated

canopy fuels. Crown fire can be of two main

forms, passive and active crown fire.

crowning index—The 20-ft windspeed (in mph)

at which active crown fire is likely to be sustained.

It is a function of canopy bulk density and crown

fire rate of spread.

duff —Partially decomposed organic material of

the forest floor beneath the litter layer.

fuel moisture—Moisture content of a specific size

class of fuel expressed as a percentage of oven dry

weight.

fuel model—A set of values that represents a

range of fuel conditions in which fire behavior

may be expected to respond similarly to changes

in fuel moisture, wind, and slope. FFE uses the 13

stylized fuel models described in Anderson (1982).

An additional fuel model (14, light-moderate

logging slash) is used within FFE to express fuel

conditions intermediate to those in fuel models 11

and 12.

hard snags—Dead trees that are not heavily

decayed yet; soft snags have 80 percent of the

wood density of hard snags.

litter—The surface layer of the forest floor that is

not in an advanced stage of decomposition, usually

consisting of freshly fallen leaves and twigs.

merchantable cubic feet—The volume, in cubic

feet, of the bole material in a stand suitable for

sale.

passive crown fire—A fire in which individual

tree crowns or groups of tree crowns burn, but a

solid flame is not consistently maintained in the

canopy layer, also called torching or candling. If

the torching index is less than the 20-ft windspeed, but the crowning index is not, then the fire

type is passive crown fire.

potential fire report—An output of FFE-FVS

that provides information about the potential fire

behavior, fire hazard, and fire effects in a stand

under two fire weather scenarios.
18

prescribed fire—Deliberate burning of wildland

fuels under specified environmental conditions.

quadratic mean diameter—The d.b.h. of a tree

with average basal area.

stand density index—A density measurement

based on the number of trees per acre and the

d.b.h. of the average tree.

surface fire—A fire that burns in the surface fuel

layer that lies just above the ground, but not in the

canopy fuels.

thin from below—A silvicultural treatment in

which trees are removed from suppressed and

intermediate crown classes, leaving the larger trees

on site.

top height—The average height (in feet) of the

40 tpa of the largest diameter.

torching index—The 20-ft windspeed (in mph)

at which crown fire initiation is expected to occur.

It is a function of surface fireline intensity, foliar

moisture content, and canopy base height.

total cubic feet—The total volume in cubic feet

of the bole material in a stand.

Acknowledgments

We thank members of the Fire and Environmental Research Applications Team at the Pacific

Wildland Fire Sciences Laboratory for their

contributions to development of the guidebook;

discussions and critiques by Don McKenzie and

Roger Ottmar were particularly helpful. James

Agee, Elizabeth Reinhardt, Russell Graham, Sarah

McCaffrey, John Szymoniak, and Theresa Jain

provided helpful guidance during development

of the guidebook. Ellen Eberhardt assisted with

formatting and editing. We are especially grateful

to Forest Service and Bureau of Land Management resource managers for their review of the

guidebook and for contributing data sets on which

the guidebook is based: Renate Bush, Louisa

Evers, Brian Ferguson, Beth Hall, Pat Jackson,

Kama Kennedy, Renee Lundberg, Bill MacArthur,

Charles Maxwell, Georgi Porter, Tim Rich, Robert

Seli, Jan Singleton, John Townsley, Eric Twombly,

Leo Yanez, and several staff members from the

Bitterroot National Forest and Boise National

Forest. Research funding was provided by the Fire

and Aviation Management staff of the Washington

Office.

This publication was reviewed by three anonymous reviewers. We appreciate the assistance of

James Agee in administering the review process.

Metric Equivalents

Multiply

When you know by: To find:

Inches (in)	 2.54	 Centimeters

Feet (ft)	 .305	 Meters

Acres (ac)	 .405	 Hectares

Square feet (ft2)	 .093	 Square meters

Tons per acre (ton/ac)	 2.24	 Megagrams

	 	 	 	 per hectare

Pounds per cubic	 16.02	 Kilograms per

	 foot (lb/ft3)	 	 	 cubic meter

Miles per hour (mph)	 .447	 Meters per

	 	 	 	 second
19

Literature Cited

Agee, J.K. 1996. The influence of forest structure

on fire behavior. In: Sherlock, J.; Landram, M.;

Gray, S., eds. Proceedings, 17th annual forest

vegetation management conference: 52–68. On

file with: James Agee, University of Washington,

College of Forest Resources, Seattle, WA.

Agee, J.K. 2002. Fire behavior and fire-resilient

forests. In: Fitzgerald, S., ed. Fire in Oregon’s

forests: risks, effects, and treatment options.

Portland, OR: Oregon Forest Resources

Institute: 119–126.

Anderson, H.E. 1982. Aids to determining fuel

models for estimating fire behavior. Res. Pap.

INT-RP-122. Ogden, UT: U.S. Department of

Agriculture, Forest Service, Intermountain

Forest and Range Experimental Station. 22 p.

Bailey, J.D.; Covington, W.W. 2002. Evaluating

ponderosa pine regeneration rates following

ecological restoration treatments in northern

Arizona, USA. Forest Ecology and Management.

155: 271–278.

Brown, R.T.; Agee, J.K.; Franklin, J.F. 2004.

Forest restoration and fire: principles in the

context of place. Conservation Biology.

18: 903–912.

Brown, T.J.; Hall, B.L.; McCurdy, G.D. 2002.

Quality control of California historical RAWS

data. CEFA Report 02-01. Reno, NV: Desert

Research Institute, Program for Climate,

Ecosystem, and Fire Applications. 29 p. http://

www.cefa.dri.edu/Publications/qcreport.pdf.

(February 14, 2005).

Carey, H.; Schuman, M. 2003. Modifying wildfire

behavior—the effectiveness of fuel treatments:

the status of our knowledge. National Commu

-

nity Forestry Center, Southwest Region Working

Paper 2. Santa Fe, NM: Forest Trust, National

Community Forestry Center. 26 p.

Crosby, J.S.; Chandler, C.C. 2004. Get the

most from your windspeed observation. Fire

Management Today. 64: 53-55. Reprinted from

Fire Control Notes 27 (Fall 1966): 12–13.

Dixon, G.E., compiler. 2002. Essential FVS:a

user’s guide to the Forest Vegetation Simulator.

Internal Rep. Fort Collins, CO: U.S. Department

of Agriculture, Forest Service, Forest

Management Service Center. 196 p.

Ferguson, D.E.; Crookston, N.L. 1991. User’s

guide to version2 of the Regeneration

Establishment Model: part of the Prognosis

Model. Gen. Tech. Rep. GTR-INT-279. Ogden,

UT: U.S. Department of Agriculture, Forest

Service, Intermountain Research Station. 26 p.

Fitzgerald, S.A. 2002. Fuel-reduction and

restoration treatments for Oregon’s forests. In:

Fitzgerald, S., ed. Fire in Oregon’s forests: risks,

effects, and treatment options. Portland, OR:

Oregon Forest Resources Institute: 127–138.

Graham, R.T.; Harvey, A.E.; Jain, T.B.; Tonn, J.R. 

1999. The effects of thinning and similar stand

treatments on fire behavior in Western forests.

Gen. Tech. Rep. PNW-GTR-463. Portland, OR:

U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 27 p.

Graham, R.T.; McCaffrey, S.; Jain, T.B. 2004. 

Scientific basis for changing forest structure

to modify wildfire behavior and severity. Gen.

Tech. Rep. GTR-RMRS-120. Fort Collins, CO:

U.S. Department of Agriculture, Forest Service,

Rocky Mountain Research Station. 43 p.

Healthy Forests Restoration Act of 2003;

P.L. 108-148.

Kalabokidis, K.D.; Omi, P.N. 1998. Reduction of

fire hazard through thinning/residue disposal

in the urban interface. International Journal of

Wildland Fire. 8: 29–35.
20

Keyes, C.R.; O’Hara, K.L. 2002. Quantifying

stand targets for silvicultural prevention

of crown fires. Western Journal of Applied

Forestry. 17: 101–109.

McDonald, P.M. 1976. Shelterwood cutting in a

young-growth, mixed-conifer stand in north

central California. Res. Pap. 117. Berkeley, CA:

U.S. Department of Agriculture, Forest Service,

Pacific Southwest Forest Range and Experiment

Station. 16 p.

National Environmental Policy Act of 1969 

[NEPA]; 42 U.S.C. 4321 et seq.

Peterson, D.L.; Johnson, M.C.; McKenzie, D.; 

Agee, J.K.; Jain, T.B.; Reinhardt, E.D. 2005.

Forest structure and fire hazard in dry forests

of the Western United States. Gen. Tech. Rep.

GTR-PNW-628. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest

Research Station. 30 p.

Pollet, J.; Omi, P.N. 2002. Effect of thinning and

prescribed burning on crown fire severity in

ponderosa pine forests. International Journal of

Wildland Fire. 11: 1–10.

Reinhardt, E.D.; Crookston, N.L., tech. eds. 

2003. The Fire and Fuels Extension to the

Forest Vegetation Simulator. Gen. Tech. Rep.

GTR-RMRS-116. Ogden, UT: U.S. Department

of Agriculture, Forest Service, Rocky Mountain

Research Station. 209 p. http://www.fs.fed.us/

rm/pubs/rmrs_gtr116.pdf. (10 May 2006).

Sackett, S.S. 1984. Observations on natural

regeneration in ponderosa pine following a

prescribed fire in Arizona. Res. Note RM435. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment Station. 8 p.

Sandberg, D.V.; Ottmar, R.D.; Cushon, G.H. 

2001. Characterizing fuels in the 21st century.

International Journal of Wildland Fire.

10: 381–387.

Scott, J.H.; Reinhardt, E.D. 2001. Assessing

crown fire potential by linking models of surface

and crown fire behavior. Res. Pap. RMRSRP-29. Fort Collins, CO: U.S. Department of

Agriculture, Forest Service, Rocky Mountain

Research Station. 59 p. http://www.fs.fed.us/rm/

pubs/rmrs_rp29.pdf (31 May 2006).

Weatherspoon, C.P. 1996. Fire-silviculture

relationships in Sierra forests. In: Sierra Nevada

Ecosystem Project: final report to Congress,

volume II, assessments and scientific basis for

management options. Davis, CA: University

of California, Centers for Water and Wildland

Resources: 1167-1176. http://ceres.ca.gov/snep/

pubs/web/PDF/VII_C44.PDF (10 May 2006).
21

Partial establishment model Full establishment model

Base FVS system TreeList Base FVS system TreeList

Cutlist Cutlist

SVS SVS

StrClass StrClass

NumCycle NumCycle

Fire and Fuels Extension FuelOut Fire and Fuels Extension FuelOut

FuelRept FuelRept

PotFire PotFire

PotFTemp PotFTemp

PotFWind PotFWind

PotFMois PotFMois

SnagSum SnagSum

SimFire SimFire

PileBurn PileBurn

Full Establishment Model NoInGrow

StockAdj

Appendix 1—Keywords used in FFE-FVS for Simulations 

Represented in the Guide
22
Initial stand conditions

A

23

Site: Elevation = 4,400 ft, slope = 24 percent, aspect = 90 percent.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 60 percent, grand fir (Abies grandis) = 31 percent, ponderosa pine (Pinus ponderosa) = 4 percent.

Stand attributes: Stem density = 2,345 tpa, basal area = 114 ft2/ac, 

top height = 78 ft, stand density index = 338, quadratic mean diameter = 3.0 in, crown competition factor = 116, canopy cover = 65 percent.

Appendix 2—Fuel Treatment Scenarios for Northern Region (Region 1)

Region 1 — Bitterroot National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

24

Region 1 — Bitterroot National Forest 1
C

25

Initial conditions/no-action trajectoryThis stand has a high tree density of 2,345 trees peracre (tpa) primarily composed of grand fir and Douglas-fir with a ponderosa pine overstory. Woody fuel

loading is 9 tons/ac, and litter and duff loading is

7 tons/ac. Canopy bulk density is 0.14 kg/m3

(0.0087 lb/ft3), and canopy base height is 3 ft,

so ladder fuels are sufficient to enable passive

crown fire, but canopy fuels are not sufficient to

enable active crown fire spread. Crowning index

is 19, and severe-weather windspeed is 17 mph, soalthough this stand is not classified as active crownfire, crown fire hazard is high. Potential basal areamortality is 97 percent for severe fire weather. With

no action, flame lengths, surface fuels, and canopy

base height increase slightly over time with crown

fire potential decreasing in 20 years and then increasing again in 40 years. Crown fire potential and flame

lengths remain low for moderate fire weather for theentire 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment decreases canopybulk density and slightly increases canopy base height,but not enough to prevent passive crown fire for severefire weather. This treatment reduces surface fuels in allsize classes, but flame lengths increase after treatmentowing to grass fuels associated with the use of fuelmodel 2; grass fuels are not tracked in FFE and may ormay not be the primary fuel following prescribed fire.All thinning treatments reduce canopy bulk densityand increase canopy base height; the greater thethinning, the greater is the change in forest structure.The predicted fire type after treatment is surface firefor all thinning options, but the more open stands arecharacterized predominantly by fuel model 2, so flamelengths increase and potential basal area mortalityremains above 20 percent regardless of surface fueltreatment. The 200 and 300 tpa treatments have amore closed canopy, and fire behavior is influenced lessby grass fuels, so flame lengths and potential basal areamortality are lower than the more open stands. Activityfuels are reduced by the pile and burn treatment and toa greater extent by the prescribed fire treatment, whichalso reduces litter and duff, but flame lengths and basalarea mortality remain high owing to grass fuels.

Silvicultural and surface fuel treatments—long-term effectsAlthough the prescribed fire only treatment does notreduce crown fire potential in the short term, after 10years the predicted fire type is surface fire, and crownfire potential continues to decline as canopy baseheight increases and flame lengths decrease. In allthinning treatments, flame lengths decrease over timeas canopy cover increases and fuel model assignmentshifts from predominantly 2 to predominantly 9. The200 tpa treatment has the greatest long-term effect oncrown fire potential with a predicted fire type of surface fire for 50 years with pile and burn or no surface

fuel treatment, and 40 years with prescribed fire treatment. The 50 tpa treatment had the most short-lived

effect on crown fire potential with regeneration causinga drop in canopy base height in 30 years regardless ofsurface fuel treatment.

Region 1 — Bitterroot National Forest 1
D

26Table 3a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 5 5 4 4

3–6 in 3 0 3 3 2 26–12 in 3 1 1 2 2 2>12 in 0 0 0 0 0 0Litter 2 1 2 2 2 2Duff 5 4 3 3 4 4

Flame length (ft) Moderate 2 3 4 3 2 2

Severe 3 5 7 6 4 3

Torching index Severe 15 8 32 38 35 27Crowning index Severe 19 51 49 45 38 38Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 25 15 9 15 19 21

Severe 97 72 68 53 29 24

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 0 0 1 1>12 in 0 0 0 0Litter 2 2 2 2Duff 2 3 3 4

Flame length (ft) Moderate 4 3 2 2

Severe 7 6 4 3

Torching index Severe 32 47 45 34Crowning index Severe 49 45 38 38Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 9 15 19 21

Severe 80 56 28 23

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 0 0 1 1Duff 2 2 3 3

Flame length (ft) Moderate 4 4 3 3

Severe 7 7 6 6

Torching index Severe 30 31 32 26Crowning index Severe 53 52 51 51Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 9 11 14 14

Severe 88 81 61 54

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 1 — Bitterroot National Forest 1
E

27

Table 3b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 3 3 4 4 4 1 3 2 2 2 3

3–6 in 3 2 3 3 3 4 0 2 2 3 3 36–12 in 3 2 2 2 2 3 1 2 2 2 2 2>12 in 0 0 0 1 2 2 0 1 1 2 2 2Litter 2 2 2 3 3 3 1 1 1 2 2 2Duff 5 5 5 6 6 6 4 4 4 4 4 4

Flame length (ft) Moderate 2 2 2 2 2 2 3 3 2 2 2 2

Severe 3 3 3 3 3 3 5 5 4 4 3 3

Torching index Severe 15 17 24 20 9 7 8 19 30 42 53 54Crowning index Severe 19 19 19 19 19 20 51 46 43 41 41 40Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 195 316 374 330 286 241 608 17 22 19 18 16

18–29.9 in 0 1 2 2 3 4 1 1 1 2 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 5 2 2 2 2 2 5 2 2 2 2 2

3–6 in 3 3 3 3 3 3 3 3 3 3 3 36–12 in 1 1 1 1 1 1 2 1 1 1 2 2>12 in 0 0 0 0 1 1 0 0 0 1 1 1Litter 2 1 1 1 1 2 2 1 1 1 2 2Duff 3 3 3 3 3 3 3 3 3 4 4 4

Flame length (ft) Moderate 4 3 3 3 3 2 3 3 3 3 2 2

Severe 7 7 6 5 5 4 6 5 5 4 4 4

Torching index Severe 32 39 48 1 0 16 38 59 68 84 97 111Crowning index Severe 49 48 47 47 46 46 45 42 39 38 38 38Type of fire Moderate Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 3 4 21 20 17 2 5 7 26 27 24

18–29.9 in 0 0 1 1 2 2 0 0 1 1 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 1
F

28Table 3b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 2 2 2 1 1 2 2 2 2

3–6 in 1 1 1 1 1 2 1 1 1 1 2 26–12 in 0 0 0 0 1 1 0 0 1 1 1 1>12 in 0 0 0 0 1 1 0 0 0 1 1 1Litter 2 1 1 1 1 2 2 1 1 2 2 2Duff 2 2 3 3 3 3 3 3 3 3 3 3

Flame length (ft) Moderate 4 3 3 3 3 2 3 3 3 2 2 2

Severe 7 7 6 5 5 4 6 5 5 4 4 4

Torching index Severe 32 39 48 2 0 13 47 59 69 85 14 114Crowning index Severe 49 48 47 47 46 46 45 42 39 37 37 37Type of fire Moderate Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 1 3 4 22 21 18 2 5 7 28 29 25

18–29.9 in 0 0 1 1 2 2 0 0 1 1 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 1 2 2 0 1 1 2 2 2

3–6 in 1 1 1 1 2 2 1 2 2 2 2 26–12 in 1 1 1 1 1 1 1 2 2 2 2 2>12 in 0 1 1 1 2 2 0 1 1 1 2 2Litter 0 1 1 1 1 2 2 1 1 1 1 2Duff 2 2 2 2 2 2 3 2 2 3 3 3

Flame length (ft) Moderate 4 4 3 3 3 2 3 3 3 3 3 2

Severe 7 7 7 6 5 4 6 6 6 5 4 4

Torching index Severe 32 32 42 0 0 6 38 41 52 0 0 7Crowning index Severe 49 51 51 50 50 50 45 49 46 44 43 43Type of fire Moderate Surface Surface Surface Passive Passive Surface Surface Surface Surface Passive Passive Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 9 9 7 22 21 18 17 9 8 25 24 21

18–29.9 in 1 1 1 1 1 2 1 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 1
G

29

Table 3b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 2 2 3 3 3 4 2 3 3 3 3

3–6 in 2 2 2 2 3 3 2 2 2 3 3 36–12 in 2 2 2 2 2 2 2 2 2 2 2 3>12 in 0 0 0 1 1 2 0 0 0 1 2 2Litter 2 1 2 2 2 2 2 2 2 2 2 2Duff 4 4 4 4 4 5 4 4 5 5 5 5

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 2

Severe 4 3 3 3 3 3 3 3 3 3 3 3

Torching index Severe 35 73 83 99 102 95 27 47 60 62 10 8Crowning index Severe 38 37 35 33 32 32 38 32 30 29 29 28Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 7 11 15 36 36 33 9 19 27 61 60 52

18–29.9 in 0 1 1 2 3 3 0 1 2 2 3 430–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 2 2 3 3 1 2 2 3 3 3

3–6 in 1 1 1 2 2 2 1 1 1 2 2 36–12 in 1 1 1 1 1 2 1 1 1 1 1 2>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 2 1 2 2 2 2 2 2 2 2 2 2Duff 3 4 4 4 4 4 4 4 4 4 4 5

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 2

Severe 4 3 3 3 3 3 3 3 3 3 3 3

Torching index Severe 45 73 83 95 103 105 34 46 48 60 13 10Crowning index Severe 38 37 35 33 32 31 38 34 33 32 31 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 7 11 15 38 38 34 12 21 26 63 62 53

18–29.9 in 0 1 1 2 3 3 0 1 1 2 3 430–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 1
H

30

Table 3c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,345 1,989 1,669 1,391 1,155 960 216 206 191 177 164 154

Quadratic mean diameter (in) 3 3.5 4.1 4.7 5.3 6 3 9.4 10.4 11.3 12.3 13.2Total volume (ft 3) 2,956 3,561 4,108 4,622 5,105 5,577 2,673 2,924 3,422 3,926 4,439 4,936Merchantable volume (ft 3) 2,411 2,778 3,214 3,760 4,209 4,674 2,287 2,491 2,945 3,439 3,909 4,357Basal area (ft 2) 114 135 151 166 178 189 92 99 112 124 135 146Stand density index 338 373 395 410 418 424 178 186 202 216 228 239Canopy closure (percent) 65 70 73 74 75 75 41 43 46 48 49 51Crown competition factor 116 137 154 168 179 189 79 85 95 105 113 122Canopy base height (ft) 3 3 4 4 3 3 4 6 8 10 12 13Canopy bulk density (kg/m3) 0.14 0.14 0.14 0.14 0.13 0.13 0.04 0.04 0.05 0.05 0.05 0.05

Table 3b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 2 2 0 2 2 2 2 2

3–6 in 1 3 3 3 3 3 1 3 3 3 3 36–12 in 1 2 2 2 2 2 1 2 2 2 2 2>12 in 0 1 1 1 2 2 0 1 1 1 2 2Litter 1 1 1 2 2 2 1 1 1 2 2 2Duff 3 3 3 3 3 3 3 3 3 3 4 4

Flame length (ft) Moderate 3 3 3 2 2 2 3 3 3 2 2 2

Severe 6 5 5 4 3 3 6 5 4 4 3 3

Torching index Severe 32 44 57 75 10 22 26 41 54 72 11 49Crowning index Severe 51 45 42 40 39 39 51 45 42 40 39 39Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 34 10 9 28 28 25 55 11 12 30 29 26

18–29.9 in 1 1 1 2 2 3 1 1 1 2 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Bitterroot National Forest 1
I

31

Table 3c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,345 49 181 178 157 143 131 99 230 225 199 180 164

Quadratic mean diameter (in) 3 17.6 9.6 10.2 11.4 12.5 13.5 13.2 9.2 9.8 10.9 11.9 13Total volume (ft3) 2,956 2,671 2,898 3,355 3,804 4,260 4,729 2,998 3,265 3,789 4,321 4,836 5,337Merchantable volume (ft3) 2,411 2,411 2,637 3,059 3,478 3,876 4,281 2,616 2,860 3,411 3,906 4,389 4,853Basal area (ft2) 114 82 92 101 111 121 131 94 106 118 129 140 150Stand density index 338 120 170 184 193 203 214 155 202 218 229 239 248Canopy cover (percent) 65 31 33 35 38 41 44 36 39 41 43 46 47Crown competition factor 116 65 71 77 84 91 98 77 85 94 101 108 115Canopy base height (ft) 3 25 25 26 3 2 5 23 25 26 28 29 30Canopy bulk density (kg/m3) 0.14 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.06 0.06 0.06

Pile and burn Trees per acre 2,345 49 194 191 169 154 141 99 243 238 211 190 173

Quadratic mean diameter (in) 3 17.6 9.3 9.9 11 12.1 13.1 13.2 9 9.5 10.6 11.6 12.6Total volume (ft3) 2,956 2,671 2,899 3,363 3,816 4,275 4,743 2,998 3,265 3,803 4,322 4,828 5,323Merchantable volume (ft3) 2,411 2,411 2,637 3,067 3,478 3,890 4,279 2,616 2,860 3,423 3,909 4,378 4,826Basal area (ft2) 114 82 92 101 111 122 133 94 106 118 129 140 150Stand density index 338 120 173 187 196 207 218 155 204 221 231 242 251Canopy cover (percent) 65 31 33 35 39 42 45 36 39 41 44 46 48Crown competition factor 116 65 71 77 84 91 99 77 85 94 102 109 116Canopy base height (ft) 3 25 25 26 3 2 4 23 25 26 28 4 30Canopy bulk density (kg/m3) 0.14 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.06 0.06 0.06

Prescribed fire Trees per acre 2,345 49 202 199 177 162 150 99 224 220 195 178 163

Quadratic mean diameter (in) 3 17.6 8.7 9.3 10.4 11.4 12.5 13.2 8.6 9.2 10.3 11.3 12.3Total volume (ft3) 2,956 2,455 2,671 3,110 3,561 4,026 4,509 2,596 2,835 3,320 3,817 4,324 4,814Merchantable volume (ft3) 2,411 2,217 2,431 2,838 3,241 3,630 4,031 2,303 2,528 3,006 3,461 3,917 4,329Basal area (ft2) 114 82 84 93 103 115 127 94 91 101 112 124 136Stand density index 338 120 162 176 187 200 213 155 177 192 204 217 229Canopy cover (percent) 65 31 31 33 37 41 45 36 34 36 40 43 46Crown competition factor 116 65 64 70 78 86 95 77 71 78 86 95 103Canopy base height (ft) 3 26 25 27 2 2 4 24 25 27 2 2 4Canopy bulk density (kg/m3) 0.14 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.05

Region 1 — Bitterroot National Forest 1
J

32

Region 1 — Bitterroot National Forest 1

Table 3c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,345 194 317 306 273 247 224 289 472 450 392 347 310

Quadratic mean diameter (in) 3 9.9 8.3 8.9 9.9 10.9 11.8 8.3 7 7.7 8.6 9.6 10.5Total volume (ft3) 2,956 3,177 3,467 4,059 4,640 5,188 5,704 3,250 3,577 4,220 4,820 5,399 5,968Merchantable volume (ft3) 2,411 2,605 2,824 3,419 4,063 4,619 5,131 2,624 2,847 3,585 4,112 4,651 5,220Basal area (ft2) 114 104 119 133 147 159 169 107 127 145 160 174 187Stand density index 338 192 235 256 270 282 291 213 268 294 310 324 336Canopy cover (percent) 65 46 49 51 54 55 57 50 55 58 61 63 64Crown competition factor 116 92 104 115 125 134 141 99 116 131 144 156 168Canopy base height (ft) 3 12 17 18 21 22 23 7 9 11 12 3 4Canopy bulk density (kg/m3) 0.14 0.06 0.06 0.06 0.07 0.07 0.07 0.06 0.07 0.08 0.08 0.08 0.08

Pile and burn Trees per acre 2,345 194 331 319 283 255 231 289 489 467 407 360 322

Quadratic mean diameter (in) 3 9.9 8.1 8.8 9.7 10.7 11.6 8.3 6.8 7.4 8.3 9.1 10Total volume (ft3) 2,956 3,177 3,468 4,070 4,646 5,194 5,705 3,210 3,503 4,086 4,643 5,173 5,669Merchantable volume (ft3) 2,411 2,605 2,825 3,403 4,075 4,593 5,135 2,597 2,810 3,335 3,942 4,477 4,998Basal area (ft2) 114 104 119 134 147 159 170 107 123 138 152 164 175Stand density index 338 192 237 258 272 284 293 213 264 286 300 312 322Canopy cover (percent) 65 46 49 51 54 55 57 50 54 56 59 61 62Crown competition factor 116 92 104 115 125 134 142 99 112 125 137 147 156Canopy base height (ft) 3 12 17 18 20 21 23 7 9 9 11 3 3Canopy bulk density (kg/m3) 0.14 0.06 0.06 0.06 0.07 0.07 0.07 0.06 0.06 0.07 0.07 0.07 0.07

Prescribed fire Trees per acre 2,345 194 256 251 224 203 186 289 272 265 237 215 198

Quadratic mean diameter (in) 3 9.9 8.3 8.9 10 11 12 8.3 8.1 8.7 9.7 10.7 11.6

Total volume (ft3) 2,956 2,665 2,918 3,451 3,981 4,516 5,028 2,670 2,924 3,442 3,962 4,475 4,985

Merchantable volume (ft3) 2,411 2,297 2,517 3,068 3,583 4,067 4,524 2,293 2,510 3,023 3,519 4,005 4,459Basal area (ft2) 114 104 96 109 121 133 145 107 97 110 122 134 146Stand density index 338 192 190 208 222 236 248 213 194 213 226 240 252Canopy cover (percent) 65 46 39 42 45 48 51 50 40 43 47 50 53Crown competition factor 116 92 79 88 97 107 116 99 81 91 101 110 120Canopy base height (ft) 3 17 18 20 22 3 5 12 15 17 19 3 11Canopy bulk density (kg/m3) 0.14 0.04 0.04 0.05 0.05 0.05 0.05 0.04 0.04 0.05 0.05 0.05 0.05

tpa = trees per acre; d.b.h. = diameter at breast height.
K

33

Table 3d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 100 2 55 9 45

10 9 100 9 64 2 36

20 9 94 10 6 9 78 2 22

30 9 84 10 16 9 89 2 11

40 9 74 10 26 9 96 2 3 10 1

50 9 62 10 38 9 94 10 6

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 2 61 10 37 9 3 2 46 10 31 9 22

10 2 84 9 16 2 55 9 45

20 2 74 9 26 9 55 2 45

30 2 59 9 41 9 67 2 33

40 9 57 2 43 9 78 2 22

50 9 70 2 30 9 86 2 14

Pile and burn 1 2 96 9 4 2 68 9 32

10 2 84 9 16 2 55 9 45

20 2 73 9 27 9 56 2 44

30 2 56 9 44 9 68 2 32

40 9 60 2 40 9 79 2 21

50 9 75 2 25 9 89 2 11

Prescribed fire 1 2 100 0 0 2 96 9 4

10 2 97 9 3 2 82 9 18

20 2 85 9 15 2 69 9 31

30 2 64 9 36 2 51 9 49

40 9 57 2 43 9 67 2 33

50 9 74 2 26 9 81 2 19

Region 1 — Bitterroot National Forest 1
L

34Table 3d—Forest Vegetation Simulator fuel model selection (continued)

Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 67 2 18 10 15 0 0 9 90 10 10 0 0 0 0

10 9 94 2 6 0 0 0 0 9 100 0 0 0 0 0 0

20 9 100 0 0 0 0 0 0 9 100 0 0 0 0 0 0

30 9 100 0 0 0 0 0 0 9 96 10 4 0 0 0 0

40 9 98 10 2 0 0 0 0 9 87 10 13 0 0 0 0

50 9 91 10 9 0 0 0 0 9 76 10 24 0 0 0 0

Pile and burn 1 9 79 2 21 0 0 0 0 9 100 0 0 0 0 0 0

10 9 94 2 6 0 0 0 0 9 100 0 0 0 0 0 0

20 9 100 0 0 0 0 0 0 9 100 0 0 0 0 0 0

30 9 100 0 0 0 0 0 0 9 100 0 0 0 0 0 0

40 9 100 0 0 0 0 0 0 9 99 10 1 0 0 0 0

50 9 96 10 4 0 0 0 0 9 90 10 10 0 0 0 0

Prescribed fire 1 2 74 9 26 0 0 0 0 2 68 9 32 0 0 0 0

10 2 56 9 44 0 0 0 0 9 52 2 48 0 0 0 0

20 9 59 2 41 0 0 0 0 9 67 2 33 0 0 0 0

30 9 76 2 24 0 0 0 0 9 85 2 15 0 0 0 0

40 9 92 2 8 0 0 0 0 9 100 2 0 0 0 0 0

50 9 98 10 2 0 0 0 0 9 96 10 4 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.Table 3f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 3e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 17 96 2 4 10 15 50 100Moderate—75th percentile 9 74 5 7 15 22 125 150

Region 1 — Bitterroot National Forest 1
Initial stand conditions

A

35

Site: Elevation = 5,200 ft, slope = 33 percent, aspect = 360°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 91 percent, ponderosa pine (Pinus ponderosa) = 6 percent.

Stand attributes: Stem density = 452 tpa, basal area = 123 ft2/ac, top 

height = 63 ft, stand density index = 258, quadratic mean diameter = 7.1 in, crown competition factor = 134, canopy cover = 57 percent.

Region 1 — Bitterroot National Forest 2
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

36

Region 1 — Bitterroot National Forest 2
C

37

Initial conditions/no-action trajectoryThis stand has 452 trees per acre (tpa) composed primarily of Douglas-fir with a ponderosa pine overstory.

Woody fuel loading is 9 tons/ac and liter and duffloading is 12 tons/ac. Canopy base height is 13 ft andcanopy bulk density is 0.17 kg/m3 (0.0106 lb/ft3), so

ladder fuels are not sufficient to enable passive crownfire, but canopy fuels are sufficient to enable crown firespread, so the predicted fire type is conditional crownfire under severe fire weather. Potential basal areamortality is relatively low (30 percent) even for severefire weather, likely because the stand is dominatedby fire-resistant tree species. With no action, there islittle accumulation of surface fuels, and flame lengthsremain below 4 ft for the 50-year projection. Canopybase height remains high enough that passive crownfire is unlikely. Canopy bulk density decreases overtime, and is low enough after 40 years that the predicted fire type changes from conditional crown fire tosurface fire for severe fire weather. Surface fire remainsthe predicted fire type under moderate fire weather forthe 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment raises canopy baseheight and decreases canopy bulk density only slightly,but the effect is sufficient to change the predicted firetype to surface fire for severe fire weather. Surfacefuels are reduced initially, but more snags are created,which contributes to surface fuel loading in the future.Thinning to 200 tpa or less is needed to raise canopybase height significantly and reduce canopy bulkdensity enough to affect crown fire potential undersevere fire weather. Although heavy thinnings haveincreased activity fuels, canopy base height is raisedwell above expected flame length. These activity fuelsare reduced by the pile and burn treatment and to agreater extent by the prescribed fire, but this changein surface fuels does not reduce flame lengths, becausethe heavily thinned stands with low woody surfacefuels are characterized by fuel model 2 with grassfuels driving predicted fire behavior. The 200 and 300tpa treatments are characterized by fuel model 9 aftersurface fuel treatments and therefore have lower flamelengths. The influence of grass fuels on fire behavior issite specific, and grass fuels are not tracked in the FFE,so these results should be interpreted cautiously.

Silvicultural and surface fuel treatments—long-term effectsThe 100 and 200 tpa treatments with pile and burnor no surface fuel treatment have a long-term effect onreducing crown fire potential. In these treatments thepredicted fire type remains surface fire, flame lengthsremain low, and canopy base height continues toincrease over time. The prescribed fire only treatmentalso has a similar effect on long-term crown fire potential. In the 50 tpa treatment, regardless of surface fuels

treatment, regeneration causes a drop in canopy baseheight in 30 yrs and the predicted fire type is passivecrown fire for severe and moderate fire weather. Alsoin this treatment, flame lengths decrease over time butremain above 5 ft for severe fire weather for the 50-yearprojection. The 300 tpa treatment is not sufficient toreduce canopy bulk density, so conditional crown fireis predicted for the entire 50-year projection, althoughflame lengths remain low and canopy base heightincreases over time.

Region 1 — Bitterroot National Forest 2
D

38Table 4a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 9 7 4 3

3–6 in 3 0 5 5 5 36–12 in 3 1 3 3 3 3>12 in 0 0 0 0 0 0Litter 2 1 3 2 2 2Duff 10 7 10 10 10 10

Flame length (ft) Moderate 2 3 3 3 2 2

Severe 3 5 5 5 3 3

Torching index Severe 57 51 120 45 26 57Crowning index Severe 15 22 50 29 18 15Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Surface Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 20 22 12 17 23 25

Severe 30 41 32 42 28 30

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 1 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 2 2 2 2Duff 9 9 9 9

Flame length (ft) Moderate 4 3 2 2

Severe 8 6 3 3

Torching index Severe 29 47 63 67Crowning index Severe 50 29 18 15Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 13 17 23 25

Severe 96 78 26 29

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 2 2 2 2>12 in 0 0 0 0Litter 0 0 1 1Duff 7 7 7 7

Flame length (ft) Moderate 4 4 3 3

Severe 8 7 5 5

Torching index Severe 31 31 49 51Crowning index Severe 57 34 24 22Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 13 17 21 22

Severe 96 96 48 41

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 1 — Bitterroot National Forest 2
E

39

Table 4b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 3 4 4 4 4 1 3 3 3 3 3

3–6 in 3 3 4 4 4 4 0 4 4 4 4 46–12 in 3 3 4 4 5 6 1 6 6 6 6 6>12 in 0 0 1 1 1 2 0 1 1 1 2 2Litter 2 2 2 2 2 2 1 1 1 1 1 1Duff 10 10 10 10 10 10 7 7 7 7 7 7

Flame length (ft) Moderate 2 2 2 2 2 3 3 3 3 3 3 3

Severe 3 3 4 4 4 4 5 5 4 4 4 4

Torching index Severe 57 18 20 66 21 27 51 41 51 57 63 67Crowning index Severe 15 16 16 16 17 18 22 23 23 23 24 24Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Cond. Cond. Cond. Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 78 82 68 59 53 48 116 20 20 16 15 16

18–29.9 in 2 2 1 1 2 2 2 2 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 9 3 2 2 1 2 7 3 2 2 2 2

3–6 in 5 5 4 4 4 3 5 5 5 4 4 46–12 in 3 3 3 3 3 3 3 3 3 3 3 4>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 3 1 1 1 1 1 2 1 1 1 1 2Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 3 4 4 4 4 3 3 3 3 3 3 3

Severe 5 8 8 7 7 5 5 6 5 5 5 4

Torching index Severe 120 25 30 0 0 15 45 45 57 70 70 88Crowning index Severe 50 44 42 41 41 40 29 28 27 26 26 26Type of fire Moderate Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 48 32 7 16 15 14 49 34 10 25 25 24

18–29.9 in 2 2 1 1 1 2 2 2 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 2
F

40Table 4b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 1 1 1 1 2 2 1 2 2 2 2

3–6 in 1 2 2 2 2 2 1 2 2 2 2 26–12 in 1 1 1 1 1 1 1 1 2 2 2 2>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 2 1 1 1 1 1 2 1 1 1 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 4 4 4 4 3 3 3 3 3 3 3 2

Severe 8 8 8 7 6 5 6 6 5 5 4 4

Torching index Severe 29 26 30 0 4 8 47 54 64 77 91 103Crowning index Severe 50 44 42 41 41 40 29 28 26 26 26 26Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 48 32 7 17 16 14 49 34 11 26 27 25

18–29.9 in 2 2 1 1 1 2 2 2 1 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 1 1 1 0 1 1 2 2 2

3–6 in 1 2 2 2 2 2 1 2 2 2 2 26–12 in 2 3 3 3 3 2 2 4 4 4 4 4>12 in 0 1 1 1 1 1 0 1 1 1 1 2Litter 0 1 1 1 1 1 2 1 1 1 1 1Duff 7 7 7 7 7 7 9 7 7 7 7 7

Flame length (ft) Moderate 4 4 4 4 3 3 4 4 3 3 3 3

Severe 8 8 8 7 6 5 7 7 6 5 5 4

Torching index Severe 31 24 29 0 4 0 31 39 49 0 8 86Crowning index Severe 57 49 46 45 44 44 34 33 31 30 30 29Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 32 15 9 15 14 13 36 16 12 23 23 21

18–29.9 in 2 2 1 1 1 1 2 2 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 2
G

41

Table 4b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 3 3 3 3 3 3 3 4 4 4 4

3–6 in 5 5 5 5 4 4 3 3 4 4 4 46–12 in 3 3 4 4 5 6 3 3 4 4 5 6>12 in 0 0 1 1 1 2 0 0 1 1 1 2Litter 2 2 2 2 2 2 2 2 2 2 2 2Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 3

Severe 3 4 4 4 4 4 3 3 4 4 4 4

Torching index Severe 26 53 59 64 64 69 57 65 65 72 72 78Crowning index Severe 18 18 18 18 18 19 15 16 15 15 15 16Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 53 41 21 40 41 37 60 53 37 51 52 49

18–29.9 in 2 2 1 1 1 2 2 2 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 3 3 3 3 1 3 3 4 4 4

3–6 in 1 2 2 2 2 3 1 1 2 2 3 36–12 in 1 1 2 3 3 4 1 1 2 3 4 5>12 in 0 0 1 1 1 2 0 0 1 1 1 2Litter 2 2 2 2 2 2 2 2 2 2 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 2

Severe 3 3 3 3 3 4 3 3 3 3 4 4

Torching index Severe 63 73 83 80 79 80 67 77 79 79 76 77

Crowning index Severe 18 18 18 18 18 19 15 16 16 16 17 18Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Surface

Hard snags (stems/ac) 0–17.9 in 53 41 21 41 42 38 62 55 39 53 53 48

18–29.9 in 2 2 1 1 1 2 2 2 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Bitterroot National Forest 2
H

42

Table 4c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 452 399 353 313 279 250 164 159 150 142 134 127

Quadratic mean diameter (in) 7.1 7.8 8.5 9.3 10.0 10.8 7.1 10.8 11.6 12.3 12.9 13.6Total volume (ft 3) 2,774 3,158 3,507 3,833 4,142 4,417 2,261 2,434 2,761 3,077 3,381 3,667Merchantable volume (ft 3) 2,097 2,508 2,879 3,292 3,596 3,866 1,838 2,000 2,338 2,682 2,973 3,233Basal area (ft 2) 123 132 140 147 153 158 97 101 109 116 122 128Stand density index 258 268 274 278 280 281 175 180 189 196 203 208Canopy closure (percent) 57 57 58 58 58 58 46 46 47 47 48 48Crown competition factor 134 142 148 151 154 156 102 105 110 114 118 121

Canopy base height (ft) 13 5 6 19 7 9 15 16 19 21 23 25

Canopy bulk density (kg/m3) 0.17 0.17 0.16 0.16 0.15 0.15 0.11 0.10 0.10 0.10 0.10 0.10

Table 4b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 3 3 3 0 3 3 3 3 3

3–6 in 1 4 4 4 4 3 1 5 4 4 4 46–12 in 2 6 6 6 6 6 2 6 6 6 6 6>12 in 0 1 1 1 2 2 0 1 1 1 2 2Litter 1 1 2 2 2 2 1 1 2 2 2 2Duff 7 7 7 7 7 7 7 7 7 7 7 7

Flame length (ft) Moderate 3 3 3 3 2 2 3 3 3 2 2 2

Severe 5 5 4 4 4 4 5 4 4 4 4 4

Torching index Severe 49 42 49 58 8 74 51 43 50 58 69 72Crowning index Severe 24 23 22 22 22 22 22 21 21 21 22 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 48 19 17 33 34 31 68 21 21 37 37 33

18–29.9 in 2 2 1 1 1 2 2 2 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 1 — Bitterroot National Forest 2
I

43

Table 4c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 452 45 154 152 138 129 122 90 197 192 171 156 142

Quadratic mean diameter (in) 7.1 14.8 8.5 9.1 10.0 11.0 11.9 12.7 9.0 9.5 10.5 11.4 12.3Total volume (ft3) 2,774 1,348 1,476 1,746 2,033 2,345 2,698 1,964 2,117 2,421 2,740 3,035 3,318Merchantable volume (ft3) 2,097 1,182 1,313 1,552 1,812 2,049 2,376 1,722 1,867 2,142 2,446 2,709 2,955Basal area (ft2) 123 55 61 68 76 85 95 80 88 95 103 110 117Stand density index 258 86 119 130 139 150 162 133 167 178 185 192 198Canopy cover (percent) 57 25 28 30 34 38 42 37 40 41 43 44 46Crown competition factor 134 49 53 58 64 71 79 79 86 91 95 100 103Canopy base height (ft) 13 28 23 25 2 5 6 22 22 24 26 28 29Canopy bulk density (kg/m3) 0.17 0.04 0.05 0.05 0.05 0.05 0.05 0.08 0.08 0.09 0.09 0.09 0.09

Pile and burn Trees per acre 452 45 165 162 148 138 131 90 208 203 181 164 151

Quadratic mean diameter (in) 7.1 14.8 8.2 8.8 9.7 10.6 11.6 12.7 8.8 9.3 10.2 11.1 12.0Total volume (ft3) 2,774 1,348 1,477 1,740 2,011 2,321 2,683 1,964 2,118 2,441 2,744 3,050 3,340Merchantable volume (ft3) 2,097 1,182 1,310 1,550 1,780 2,011 2,338 1,722 1,868 2,155 2,460 2,715 2,964Basal area (ft2) 123 55 61 68 76 85 96 80 88 96 103 111 118Stand density index 258 86 121 131 141 153 165 133 169 181 188 195 201Canopy cover (percent) 57 25 28 30 35 39 43 37 40 41 43 45 47

Crown competition factor 134 49 53 58 64 72 80 79 86 91 96 100 105Canopy base height (ft) 13 28 23 25 2 4 4 22 22 24 26 28 29Canopy bulk density (kg/m3) 0.17 0.04 0.05 0.05 0.05 0.05 0.05 0.08 0.08 0.09 0.09 0.09 0.09

Prescribed fire Trees per acre 452 45 170 167 154 145 138 90 202 198 177 163 151

Quadratic mean diameter (in) 7.1 14.8 7.6 8.2 9.1 10.1 11.1 12.7 8.2 8.7 9.6 10.5 11.4Total volume (ft3) 2,774 1,183 1,301 1,562 1,846 2,189 2,605 1,646 1,787 2,082 2,382 2,687 3,009Merchantable volume (ft3) 2,097 1,037 1,154 1,393 1,619 1,874 2,253 1,443 1,576 1,839 2,123 2,363 2,627Basal area (ft2) 123 55 54 61 70 81 93 80 74 82 90 98 107Stand density index 258 86 110 121 133 147 163 133 147 158 167 177 186Canopy cover (percent) 57 25 25 28 34 39 44 37 35 37 40 43 46Crown competition factor 134 49 47 52 59 68 78 79 71 76 82 88 94Canopy base height (ft) 13 32 23 26 2 4 4 23 22 24 3 4 20Canopy bulk density (kg/m3) 0.17 0.03 0.04 0.04 0.04 0.04 0.05 0.06 0.07 0.07 0.07 0.08 0.08

Region 1 — Bitterroot National Forest 2
J

44Table 4c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 452 200 299 288 256 230 209 290 370 347 309 276 246

Quadratic mean diameter (in) 7.1 10.2 8.7 9.2 10 10.7 11.5 8.8 8.3 8.9 9.7 10.6 11.4Total volume (ft3) 2,774 2,788 2,973 3,326 3,650 3,954 4,218 3,060 3,316 3,805 4,241 4,622 4,960Merchantable volume (ft3) 2,097 2,333 2,520 2,857 3,203 3,502 3,752 2,413 2,637 3,228 3,653 4,017 4,337Basal area (ft2) 123 114 124 132 139 145 150 123 137 150 160 167 173Stand density index 258 208 240 251 255 258 260 237 272 287 296 300 302Canopy cover (percent) 57 53 54 54 55 55 55 57 58 59 59 60 60Crown competition factor 134 123 131 136 140 144 146 135 147 155 162 166 169Canopy base height (ft) 13 13 15 17 19 21 23 13 16 18 21 23 24Canopy bulk density (kg/m3) 0.17 0.14 0.14 0.14 0.14 0.14 0.13 0.17 0.17 0.17 0.17 0.17 0.16

Pile and burn Trees per acre 452 200 310 299 265 238 215 290 379 355 315 280 250

Quadratic mean diameter (in) 7.1 10.2 8.6 9 9.8 10.6 11.3 8.8 8 8.5 9.3 10 10.7Total volume (ft3) 2,774 2,788 2,974 3,318 3,646 3,952 4,227 2,962 3,147 3,506 3,841 4,140 4,409Merchantable volume (ft3) 2,097 2,333 2,518 2,842 3,211 3,521 3,755 2,327 2,503 2,887 3,299 3,593 3,848Basal area (ft2) 123 114 124 132 139 145 150 123 132 140 147 153 158Stand density index 258 208 242 252 257 260 262 236 264 274 278 280 281Canopy cover (percent) 57 53 54 54 55 55 55 56 57 58 58 58 58Crown competition factor 134 123 131 136 140 144 146 134 142 147 151 153 156Canopy base height (ft) 13 13 15 17 19 21 23 13 15 17 20 21 23Canopy bulk density (kg/m3) 0.17 0.14 0.14 0.14 0.14 0.14 0.14 0.17 0.16 0.16 0.16 0.15 0.14

Prescribed fire Trees per acre 452 200 267 259 231 209 190 290 290 279 248 224 204

Quadratic mean diameter (in) 7.1 10.2 8.2 8.7 9.5 10.3 11.1 8.8 8 8.5 9.3 10.1 10.9Total volume (ft3) 2,774 2,176 2,351 2,693 3,024 3,329 3,612 2,261 2,438 2,789 3,127 3,452 3,757Merchantable volume (ft3) 2,097 1,841 2,019 2,327 2,677 2,952 3,196 1,837 2,003 2,368 2,731 3,023 3,301Basal area (ft2) 123 114 98 106 114 121 128 123 102 110 118 126 132Stand density index 258 208 194 206 213 219 224 236 203 215 222 229 234Canopy cover (percent) 57 53 46 47 48 50 51 56 47 48 49 51 52Crown competition factor 134 123 101 106 112 117 121 134 106 112 117 122 126Canopy base height (ft) 13 16 16 18 20 4 24 15 16 18 20 23 24Canopy bulk density (kg/m3) 0.17 0.10 0.11 0.11 0.11 0.11 0.11 0.11 0.12 0.12 0.11 0.11 0.11

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Bitterroot National Forest 2
K

45

Table 4d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 93 10 7 9 73 2 27

10 9 88 10 12 9 59 10 29 2 13

20 9 78 10 22 9 63 10 26 2 11

30 9 71 10 29 9 64 10 27 2 10

40 9 65 10 35 9 64 10 27 2 9

50 9 58 10 42 9 63 10 29 2 8

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent

None 1 11 65 2 18 10 17 11 49 2 25 9 14 10 12

10 2 83 10 17 2 44 9 41 10 15

20 2 99 9 1 9 51 2 43 10 6

30 2 79 9 21 9 61 2 35 10 3

40 2 59 9 41 9 69 2 27 10 4

50 9 58 2 42 9 74 2 19 10 6

Pile and burn 1 2 100 2 63 9 37

10 2 100 2 52 9 48

20 2 98 9 2 9 56 2 44

30 2 77 9 23 9 65 2 35

40 2 55 9 45 9 75 2 25

50 9 64 2 36 9 83 2 17

Prescribed fire 1 2 100 2 92 9 8

10 2 100 2 76 9 24

20 2 100 2 66 9 34

30 2 81 9 19 2 51 9 49

40 2 54 9 46 9 65 2 35

` 50 9 69 2 31 9 78 2 22

Region 1 — Bitterroot National Forest 2
L

46

Table 4f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 4e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 17 96 2 4 10 15 50 100Moderate—75th percentile 9 74 5 7 15 22 125 150Table 4d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 9 64 11 36 0 9 93 10 7

10 9 82 10 18 0 9 87 10 13

20 9 79 10 21 0 9 75 10 25

30 9 75 10 25 0 9 67 10 33

40 9 71 10 29 0 9 59 10 41

50 9 65 10 35 0 9 50 10 50

Pile and burn 1 9 100 0 9 100

10 9 100 0 9 100

20 9 100 0 9 96 10 4

30 9 93 10 7 0 9 85 10 15

40 9 86 10 14 0 9 78 10 22

50 9 79 10 21 0 9 69 10 31

Prescribed fire 1 9 64 2 36 0 9 73 2 27

10 9 63 10 20 2 18 0 9 61 10 29 2 10

20 9 65 10 21 2 13 0 9 64 10 29 2 7

30 9 71 10 22 2 7 0 9 68 10 30 2 2

40 9 75 10 23 2 2 0 9 70 10 30

50 9 74 10 26 0 9 69 10 31

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Bitterroot National Forest 2
Initial stand conditions

A

47

Region 1 — Gallatin National Forest

Site: Elevation = 5,200 ft, slope = 40 percent, aspect = 225°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 74 percent, hardwoods = 23 percent, ponderosa pine (Pinus ponderosa) = 2 percent.

Stand attributes: Stem density = 873 tpa, basal area = 197 ft2/ac, top height = 75 ft, stand density index = 430, quadratic mean diameter = 6.4 in, crown competition factor = 280, canopy cover = 71 percent.
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

48

Region 1 — Gallatin National Forest
C

49

Initial conditions/no-action trajectoryThis stand has initial tree density of 873 trees peracre (tpa) composed of Douglas-fir and hardwoodunderstory with Douglas-fir and ponderosa pineoverstory. Woody fuel loading is 10 tons/ac, and literand duff loading is 12 tons/ac. Canopy bulk density is0.21 kg/m3 (0.0131 lb/ft3), and canopy base height is

7 ft, so ladder fuels are not sufficient to enable passivecrown fire. Canopy fuels are sufficient to sustain crownfire spread, so the predicted fire type is conditionalcrown fire for severe fire weather. Predicted basal areamortality is about 25 percent for moderate and severefire weather. With no action, surface fuels accumulateand potential flame lengths increase, but canopy baseheight also increases, so passive crown fire remainsunlikely. Canopy bulk density remains high, so thepredicted fire type for severe fire weather is conditionalcrown fire for the 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment raises canopybase height and decreases canopy bulk density onlyslightly, so there is little change in crown fire potential.Surface fuels are consumed, and flame lengths decreaseimmediately after treatment. All thinning treatmentsreduce canopy bulk density and increase canopy baseheight, but thinning to 100 tpa or less is necessaryto decrease crown fire potential. However, the lowerdensity thinning treatments greatly increase surfacefuel loading and have higher potential flame lengthsand basal area mortality. Activity fuels are reduced bythe pile and burn treatment and to a greater extent bythe prescribed fire treatment, but flame lengths andbasal area mortality increase following surface fueltreatments in the low-density treatments, because firebehavior predictions are dominated by fuel model 2. Inthe high-density treatments, activity fuels are reducedby surface fuel treatments causing a decrease in potential flame lengths and basal area mortality.

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, surface fuels andflame lengths increase in 10 years as snags fall andcontribute to surface fuel loading, but after 10 years,surface fuels and flame lengths decrease. Canopy bulkdensity remains high, so the predicted fire type isconditional crown fire for the 50-year projection. In thelower density treatments (50 and 100 tpa), predictedfire type is surface fire for the 50-year projection,and potential flame lengths decrease over time as theinfluence of grass fuels declines. Crown fire potentialcontinues to decrease over time as trees grow andthe stand self-thins, causing canopy base height toincrease. In the higher density treatments (200 and300 tpa), canopy bulk density remains high and thepredicted fire type for severe fire weather is conditionalcrown fire for the 50-year projection except in the 200tpa treatment with a prescribed fire. In this treatment,additional fire-caused tree mortality reduces canopybulk density, and the predicted fire type changes fromconditional crown fire to surface fire in 20 years.

Region 1 — Gallatin National Forest
D

50Table 5a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 12 10 7 5

3–6 in 4 0 6 6 6 56–12 in 3 2 3 3 3 3>12 in 0 0 0 0 0 0Litter 2 1 4 3 3 3Duff 10 7 10 10 10 10

Flame length (ft) Moderate 2 1 4 4 3 2

Severe 2 1 6 5 3 3

Torching index Severe 163 234 116 163 262 105Crowning index Severe 13 17 45 24 13 13Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Conditional Surface Surface Conditional Conditional

Potential basal area mortality (%) Moderate 26 20 13 13 17 21

Severe 27 20 33 25 19 24

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 2

3–6 in 2 2 2 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 3 3 3 2Duff 9 9 9 9

Flame length (ft) Moderate 5 3 1 1

Severe 8 5 1 1

Torching index Severe 36 147 782 315Crowning index Severe 45 24 13 13Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Conditional Conditional

Potential basal area mortality (%) Moderate 18 12 17 21

Severe 92 31 17 21

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 16–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 1Duff 7 7 7 7

Flame length (ft) Moderate 5 4 2 1

Severe 9 6 3 1

Torching index Severe 36 80 362 255Crowning index Severe 48 28 17 17Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Conditional Conditional

Potential basal area mortality (%) Moderate 18 14 16 18

Severe 93 58 16 18

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 1 — Gallatin National Forest
E

51

Table 5b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 5 6 6 6 7 1 5 4 4 4 4

3–6 in 4 4 4 4 4 5 0 4 4 4 4 46–12 in 3 3 3 4 4 4 2 5 5 5 5 5>12 in 0 0 0 1 2 2 0 1 1 2 2 2Litter 2 3 3 3 3 3 1 2 2 2 2 2Duff 10 10 10 11 11 11 7 7 7 8 8 8

Flame length (ft) Moderate 2 2 3 3 3 3 1 3 2 2 3 3

Severe 2 3 4 4 4 4 1 4 3 4 4 4

Torching index Severe 163 128 91 77 56 48 234 70 95 111 82 85Crowning index Severe 13 13 13 13 14 14 17 20 20 20 19 19Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 146 98 38 40 34 34 187 16 14 12 11 9

18–29.9 in 0 1 2 2 3 3 1 1 1 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 12 5 3 2 2 2 10 5 3 3 3 3

3–6 in 6 5 5 4 4 4 6 5 5 5 4 46–12 in 3 3 3 3 2 2 3 3 3 3 3 3>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 4 1 1 1 2 2 3 2 2 2 2 2Duff 10 10 10 10 10 10 10 10 10 10 10 11

Flame length (ft) Moderate 4 5 5 4 4 4 4 3 3 2 2 2

Severe 6 7 7 7 7 6 5 5 4 3 3 3

Torching index Severe 116 33 46 62 82 95 163 116 250 427 517 488Crowning index Severe 45 43 42 44 44 45 24 26 26 27 27 27Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 132 74 5 6 6 6 133 75 7 8 9 9

18–29.9 in 0 1 1 2 2 2 0 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Gallatin National Forest
F

52Table 5b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 2 2 2 2 2 2 3 3 3

3–6 in 2 2 2 2 2 3 2 2 2 2 2 36–12 in 1 1 1 1 1 1 1 1 1 1 1 2>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 3 1 1 1 2 2 3 2 2 2 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 5 5 5 4 4 4 3 3 2 2 1 1

Severe 8 8 7 7 7 6 5 4 3 3 2 2

Torching index Severe 36 34 48 65 84 103 147 213 377 613 838 773Crowning index Severe 45 43 42 43 44 45 24 26 26 27 27 27Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 132 74 5 6 6 6 133 75 7 9 9 9

18–29.9 in 0 1 1 2 2 2 0 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 2 2 0 2 2 2 2 3

3–6 in 2 2 2 2 2 3 2 2 2 2 3 36–12 in 2 2 2 2 2 2 2 3 3 3 3 3>12 in 0 1 1 2 2 2 0 1 1 2 2 2Litter 1 1 1 1 1 2 3 1 2 2 2 2Duff 7 7 7 7 7 7 9 7 7 7 7 7

Flame length (ft) Moderate 5 5 5 5 5 4 4 4 3 3 3 3

Severe 9 8 8 8 7 7 6 5 5 4 4 4

Torching index Severe 36 41 45 58 68 76 80 120 180 258 317 307Crowning index Severe 48 47 46 47 48 48 28 29 30 30 31 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 58 10 8 7 6 6 66 15 11 9 8 9

18–29.9 in 1 1 1 2 2 2 1 1 1 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Gallatin National Forest 
G

53

Table 5b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 7 4 4 4 4 5 5 4 4 5 6 5

3–6 in 6 5 5 5 5 5 5 5 5 5 5 56–12 in 3 3 3 3 3 3 3 3 3 3 4 4>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 3 2 2 2 2 3 3 3 3 3 3 3Duff 10 10 10 11 11 11 10 10 10 11 11 11

Flame length (ft) Moderate 3 2 2 2 2 2 2 2 2 3 3 3

Severe 3 3 3 3 3 4 3 3 3 4 4 4

Torching index Severe 262 225 428 435 412 389 105 185 263 238 235 224Crowning index Severe 13 17 18 18 18 18 13 15 16 16 16 16

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 134 77 10 11 12 12 135 79 14 23 25 23

18–29.9 in 0 1 1 1 2 2 0 1 1 2 3 430–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 3 3 4 4 4 2 3 4 5 6 5

3–6 in 2 2 2 2 3 3 1 2 2 2 3 36–12 in 1 1 1 1 2 2 1 1 1 2 2 3>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 3 2 2 2 2 3 2 3 3 3 3 3Duff 9 9 9 9 10 10 9 9 9 10 10 10

Flame length (ft) Moderate 1 1 1 1 2 2 1 1 1 2 2 3

Severe 1 1 1 2 3 3 1 1 2 3 3 4

Torching index Severe 782 702 1038 775 612 554 315 562 498 361 320 294Crowning index Severe 13 17 18 17 17 17 13 15 16 16 16 16

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 134 77 10 11 12 12 135 79 15 23 25 24

18–29.9 in 0 1 1 1 2 2 0 1 1 2 3 430–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Gallatin National Forest
H

54

Table 5c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 873 843 847 817 834 809 307 304 298 292 286 282

Quadratic mean diameter (in) 6.4 6.9 7.1 7.5 7.7 8.0 6.4 9.9 10.4 11.0 11.5 12.0Total volume (ft 3) 4,211 4,984 5,763 6,529 7,347 8,155 3,722 4,077 4,816 5,587 6,389 7,252Merchantable volume (ft 3) 3,327 4,005 4,787 5,397 6,156 6,811 3,136 3,504 4,201 4,891 5,612 6,472Basal area (ft 2) 197 216 234 250 267 282 153 162 177 193 208 223Stand density index 430 460 491 514 543 565 286 298 320 340 360 380Canopy closure (percent) 71 71 72 72 72 72 56 58 60 60 61 62Crown competition factor 280 300 318 334 351 365 184 192 207 222 236 251Canopy base height (ft) 7 10 10 10 9 9 8 10 10 12 10 11Canopy bulk density (kg/m3) 0.21 0.21 0.20 0.20 0.19 0.20 0.16 0.13 0.13 0.13 0.13 0.14

Table 5b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 3 3 3 4 0 4 3 3 4 4

3–6 in 2 3 3 3 3 4 1 4 4 4 4 46–12 in 2 5 5 5 5 5 2 5 5 5 5 5>12 in 0 1 1 2 2 2 0 1 1 2 2 2Litter 1 2 2 2 2 2 1 2 2 2 2 2Duff 7 7 7 7 8 8 7 7 7 8 8 8

Flame length (ft) Moderate 2 2 2 2 2 2 1 2 2 2 2 3

Severe 3 3 3 3 3 3 1 3 3 3 4 4

Torching index Severe 362 367 456 469 436 404 255 153 231 274 269 266Crowning index Severe 17 20 21 22 22 22 17 20 21 21 21 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Surface Surface Surface Surface Cond. Cond. Cond. Surface Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 75 16 13 10 10 11 90 17 14 12 12 12

18–29.9 in 1 1 1 2 2 2 1 1 1 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 1 — Gallatin National Forest
I

55

Table 5c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 873 50 127 123 121 118 115 99 175 171 167 163 160

Quadratic mean diameter (in) 6.4 18.0 11.8 12.4 13.1 13.7 14.3 14.8 11.7 12.4 13.0 13.6 14.2Total volume (ft3) 4,211 2,736 2,982 3,501 4,053 4,643 5,249 3,376 3,689 4,348 5,047 5,769 6,521Merchantable volume (ft3) 3,327 2,452 2,728 3,184 3,708 4,250 4,834 2,989 3,327 3,924 4,585 5,284 5,986Basal area (ft2) 197 87 96 104 112 121 129 119 131 143 154 166 177

Stand density index 430 127 165 175 185 195 205 187 226 241 255 269 282Canopy cover (percent) 71 29 31 32 34 35 37 42 44 46 48 50 50Crown competition factor 280 76 82 88 95 102 109 119 129 139 149 159 169

Canopy base height (ft) 7 30 24 28 30 34 36 26 24 29 33 36 39Canopy bulk density (kg/m3) 0.21 0.05 0.05 0.05 0.05 0.05 0 0.10 0.09 0.09 0.09 0.09 0.09

Pile and burn Trees per acre 873 50 134 131 128 125 122 99 183 179 175 171 167

Quadratic mean diameter (in) 6.4 18.0 11.4 12.1 12.7 13.3 13.9 14.8 11.5 12.1 12.7 13.3 13.9Total volume (ft3) 4,211 2,736 2,982 3,501 4,053 4,642 5,248 3,376 3,689 4,348 5,046 5,769 6,517Merchantable volume (ft3) 3,327 2,452 2,728 3,184 3,708 4,250 4,834 2,989 3,327 3,924 4,583 5,284 5,986Basal area (ft2) 197 87 96 104 112 121 129 119 131 143 154 166 177

Stand density index 430 127 166 177 187 197 207 187 228 243 257 271 284Canopy cover (percent) 71 29 31 33 34 36 37 42 43 45 47 48 49Crown competition factor 280 76 82 88 96 102 109 119 129 139 150 159 169

Canopy base height (ft) 7 30 24 28 31 34 37 26 24 29 33 36 39Canopy bulk density (kg/m3) 0.21 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.09 0.09 0.09 0.09 0.09

Prescribed fire Trees per acre 873 50 137 134 130 127 124 99 175 171 167 163 160

Quadratic mean diameter (in) 6.4 18.0 10.9 11.5 12.1 12.7 13.3 14.8 11.0 11.7 12.3 12.9 13.5Total volume (ft3) 4,211 2,533 2,765 3,253 3,772 4,327 4,898 3,030 3,317 3,924 4,569 5,239 5,938Merchantable volume (ft3) 3,327 2,271 2,528 2,982 3,466 3,961 4,527 2,690 3,004 3,558 4,190 4,797 5,432Basal area (ft2) 197 87 88 96 104 112 119 119 116 127 137 148 158Stand density index 430 127 157 167 177 186 196 187 204 218 232 245 257Canopy cover (percent) 71 29 29 30 32 33 35 42 40 42 44 45 46Crown competition factor 280 76 75 81 88 94 101 119 112 121 131 140 148Canopy base height (ft) 7 30 33 34 37 36 39 26 27 29 32 35 39

Canopy bulk density (kg/m3) 0.21 0.04 0.04 0.04 0.04 0.04 0.04 0.08 0.08 0.08 0.08 0.08 0.07

Region 1 — Gallatin National Forest
J

56Table 5c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 873 198 272 266 260 254 249 300 372 363 348 335 323

Quadratic mean diameter (in) 6.4 12.1 10.8 11.4 12.0 12.5 13.1 10.4 9.9 10.4 10.9 11.4 11.9Total volume (ft3) 4,211 4,122 4,504 5,302 6,147 7,015 7,895 4,407 4,817 5,655 6,397 7,157 7,934Merchantable volume (ft3) 3,327 3,600 3,982 4,718 5,547 6,300 7,204 3,642 4,101 4,924 5,635 6,326 7,082Basal area (ft2) 197 157 173 188 203 218 231 178 197 215 227 239 251Stand density index 430 268 308 328 347 365 382 321 363 387 402 416 429Canopy cover (percent) 71 55 58 61 62 63 63 64 67 68 67 67 67

Crown competition factor 280 178 192 206 220 233 246 216 234 251 262 273 284Canopy base height (ft) 7 26 22 31 34 38 41 9 15 20 25 29 32Canopy bulk density (kg/m3) 0.21 0.21 0.16 0.15 0.15 0.15 0.15 0.21 0.17 0.17 0.17 0.17 0.17

Pile and burn Trees per acre 873 198 280 274 267 261 256 300 380 370 355 341 330

Quadratic mean diameter (in) 6.4 12.1 10.6 11.2 11.8 12.4 12.9 10.4 9.8 10.3 10.8 11.3 11.8Total volume (ft3) 4,211 4,122 4,504 5,302 6,147 7,015 7,904 4,407 4,817 5,644 6,385 7,145 7,922

Merchantable volume (ft3) 3,327 3,600 3,982 4,718 5,547 6,298 7,212 3,642 4,101 4,913 5,624 6,316 7,069Basal area (ft2) 197 157 173 188 203 218 232 178 197 214 227 239 250Stand density index 430 268 309 330 349 367 385 321 365 388 403 417 430Canopy cover (percent) 71 55 58 61 62 63 63 64 67 67 67 67 67

Crown competition factor 280 178 192 206 220 233 246 216 234 250 262 273 284Canopy base height (ft) 7 26 22 31 34 38 41 9 15 19 25 29 32Canopy bulk density (kg/m3) 0.21 0.21 0.16 0.15 0.15 0.15 0.15 0.21 0.17 0.17 0.17 0.17 0.17

Prescribed fire Trees per acre 873 198 239 234 229 223 219 300 286 280 274 268 262

Quadratic mean diameter (in) 6.4 12.1 10.5 11.1 11.7 12.3 12.9 10.4 10.0 10.6 11.2 11.7 12.3Total volume (ft3) 4,211 3,527 3,864 4,577 5,346 6,148 6,952 3,668 4,020 4,769 5,560 6,378 7,202

Merchantable volume (ft3) 3,327 3,099 3,444 4,099 4,829 5,599 6,342 3,123 3,544 4,216 4,965 5,777 6,545Basal area (ft2) 197 157 144 157 171 185 197 178 156 172 187 201 215Stand density index 430 268 259 277 295 312 328 321 286 307 328 346 363Canopy cover (percent) 71 55 51 53 55 57 58 64 56 59 60 61 62

Crown competition factor 280 178 154 166 179 192 203 216 175 189 204 218 231Canopy base height (ft) 7 26 26 30 33 36 40 9 15 20 25 28 31Canopy bulk density (kg/m3) 0.21 0.15 0.13 0.12 0.11 0.11 0.11 0.16 0.13 0.12 0.12 0.12 0.12

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Gallatin National Forest
K

57

Table 5d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 87 10 13 0 0 0 0 8 100 0 0 0 0 0 0

10 8 66 10 34 0 0 0 0 8 52 10 48 0 0 0 0

20 8 51 10 49 0 0 0 0 8 64 10 36 0 0 0 0

30 10 58 8 42 0 0 0 0 8 61 10 39 0 0 0 0

40 10 68 8 32 0 0 0 0 8 57 10 43 0 0 0 0

50 10 75 8 25 0 0 0 0 8 52 10 48 0 0 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 11 73 14 27 0 0 0 0 11 92 14 8 0 0 0 0

10 2 62 10 36 8 3 0 0 8 46 10 35 2 18 0 0

20 2 80 8 11 10 9 0 0 8 69 10 16 2 15 0 0

30 2 78 8 20 10 1 0 0 8 82 10 10 2 8 0 0

40 2 72 8 27 10 1 0 0 8 84 10 14 2 2 0 0

50 2 63 8 31 10 6 0 0 8 78 10 22 0 0 0 0

Pile and burn 1 2 86 10 14 0 0 0 0 8 57 2 40 10 3 0 0

10 2 96 8 4 0 0 0 0 8 72 2 28 0 0 0 0

20 2 87 8 13 0 0 0 0 8 82 2 18 0 0 0 0

30 2 79 8 21 0 0 0 0 8 91 2 9 0 0 0 0

40 2 72 8 28 0 0 0 0 8 96 2 4 0 0 0 0

50 2 67 8 33 0 0 0 0 8 92 10 8 0 0 0 0

Prescribed fire 1 2 100 0 0 0 0 0 0 2 65 8 35 0 0 0 0

10 2 100 0 0 0 0 0 0 2 51 8 49 0 0 0 0

20 2 98 8 2 0 0 0 0 8 61 2 39 0 0 0 0

30 2 90 8 10 0 0 0 0 8 69 2 29 10 1 0 0

40 2 83 8 17 0 0 0 0 8 72 2 21 10 7 0 0

50 2 77 8 23 0 0 0 0 8 71 2 15 10 14 0 0

Region 1 — Gallatin National Forest
L

58

Region 1 — Gallatin National Forest

Table 5d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models 0 Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent Percent

None 1 11 73 8 27 0 0 0 0 8 52 11 48 0 0 0 0

10 8 65 10 35 0 0 0 0 8 67 10 33 0 0 0 0

20 8 75 10 25 0 0 0 0 8 69 10 31 0 0 0 0

30 8 71 10 29 0 0 0 0 8 53 10 47 0 0 0 0

40 8 63 10 37 0 0 0 0 10 56 8 44 0 0 0 0

50 8 58 10 42 0 0 0 0 10 64 8 36 0 0 0 0

Pile and burn 1 8 100 0 0 0 0 0 0 8 100 0 0 0 0 0 0

10 8 100 0 0 0 0 0 0 8 100 0 0 0 0 0 0

20 8 100 0 0 0 0 0 0 8 92 10 8 0 0 0 0

30 8 91 10 9 0 0 0 0 8 72 10 28 0 0 0 0

40 8 79 10 21 0 0 0 0 8 61 10 39 0 0 0 0

50 8 72 10 28 0 0 0 0 8 51 10 49 0 0 0 0

Prescribed fire 1 8 84 2 16 0 0 0 0 8 100 0 0 0 0 0 0

10 8 83 10 17 0 0 0 0 8 68 10 32 0 0 0 0

20 8 83 10 17 0 0 0 0 8 70 10 30 0 0 0 0

30 8 80 10 20 0 0 0 0 8 67 10 33 0 0 0 0

40 8 73 10 27 0 0 0 0 8 60 10 40 0 0 0 0

50 8 64 10 36 0 0 0 0 8 53 10 47 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.Table 5f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 5e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 21 94 3 5 8 16 50 100Moderate—75th percentile 13 80 5 7 10 23 125 150
Initial stand conditions

A

59

Site: Elevation = 6,200 ft, slope = 27 percent, aspect = 90°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 76 percent, hardwoods = 13 percent, ponderosa pine (Pinus ponderosa) = 11 percent.

Stand attributes: Stem density = 707 tpa, basal area = 195 ft2/ac, top height = 47 ft, stand density index = 408, quadratic mean diameter = 7.1 in, crown competition factor = 281, canopy cover = 81 percent.

Region 1 — Lewis and Clark National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

60

Region 1 — Lewis and Clark National Forest 1
C

61

Initial conditions/no-action trajectoryThis stand has initial tree density of 707 trees per acre(tpa) composed of Douglas-fir and hardwood understory and Douglas-fir and ponderosa pine overstory.

Woody fuel loading is 9 tons/ac, and liter and duffloading is 13 tons/ac. Canopy bulk density is 0.29

kg/m3 (0.0181 lb/ft3), and canopy base height is 6 ft.

Ladder fuels are not sufficient to enable passive crownfire, but canopy fuels are sufficient to sustain crownfire spread should a crown fire enter the stand undersevere fire weather conditions. Predicted basal areamortality is 34 percent for moderate fire weather and57 percent for severe fire weather. With no action,canopy base height declines in 20 years as small treesmove into the canopy, and active crown fire becomeslikely. In 30 years, canopy base height increases as thestand self-thins, and the predicted fire type becomesconditional crown fire again. Surface fuels accumulateslowly over time, but potential flame lengths remain 4ft or less for the 50-year projection.

Silvicultural and surface fuel treatments—

immediate effectsThe prescribed fire only treatment raises canopy baseheight and decreases canopy bulk density, but notenough to significantly affect crown fire potential.Surface fuels are consumed in the prescribed fire butincrease greatly in 10 years. All thinning treatmentsreduce canopy bulk density and increase canopy baseheight, but thinning to 200 tpa or less is necessaryto decrease canopy bulk density sufficiently to affectcrown fire potential. However, the lower densitythinning treatments greatly increase surface fuelloading causing higher potential flame lengths andbasal area mortality. Activity fuels are reduced by thepile and burn treatment and, to a greater extent, by theprescribed fire treatment, but flame lengths and basalarea mortality decrease only slightly following treatment because fire behavior predictions are dominated

by fuel models 1 and 2 rather than 8. Grass fuels arenot tracked well in FFE and may or may not be theprimary surface fuel following treatment; the influenceof grass fuels should be interpreted with caution.

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, surface fuelsincrease in 10 years as snags fall and contribute tosurface fuel loading, but after 10 years surface fuelsand flame lengths stabilize. Canopy bulk densityremains high enough that the predicted fire type isconditional crown fire for the 50-year projection. Thelower density treatments (50, 100, and 200 tpa) havethe greatest long-term effect on crown fire potential. Inthese treatments, the predicted fire type is surface firefor the 50-year projection, and potential flame lengthsdecrease over time as the influence of grass fuelsdeclines. Crown fire potential continues to decline astree growth and self-thinning cause canopy base heightto increase. In the highest density treatment (300 tpa),canopy bulk density remains high; the predicted firetype for severe fire weather is conditional crown fire forthe 50-year projection except for the 300 tpa treatmentwith a prescribed fire surface fuel treatment. In thistreatment, additional fire-caused tree mortality reducescanopy bulk density, and the predicted fire typechanges from conditional crown fire to surface fire.

Region 1 — Lewis and Clark National Forest 1
D

62Table 6a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 14 12 9 7

3–6 in 3 0 7 7 7 76–12 in 3 2 4 4 4 4>12 in 0 0 0 0 0 0Litter 3 1 5 4 4 3Duff 10 7 10 10 10 10

Flame length (ft) Moderate 3 3 5 4 3 2

Severe 4 4 6 5 4 3

Torching index Severe 18 35 37 52 82 82Crowning index Severe 11 16 45 28 19 14Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Conditional Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 34 32 22 21 25 27

Severe 57 65 94 60 30 29

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 2 2

3–6 in 2 2 2 26–12 in 1 1 1 1>12 in 0 0 0 0Litter 4 4 4 3Duff 9 9 9 9

Flame length (ft) Moderate 3 3 3 3

Severe 5 5 5 4

Torching index Severe 22 26 30 40Crowning index Severe 45 28 19 14Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 18 21 25 28

Severe 48 45 67 57

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 0 1 1 1Duff 7 7 7 7

Flame length (ft) Moderate 4 3 3 3

Severe 5 4 5 5

Torching index Severe 29 34 27 31Crowning index Severe 51 34 23 19Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 18 21 24 27

Severe 42 32 68 73

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 1 — Lewis and Clark National Forest 1
E

63

Table 6b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 6 7 7 7 6 1 6 5 4 4 4

3–6 in 3 3 3 4 4 4 0 5 5 5 4 46–12 in 3 3 4 4 5 5 2 7 7 7 6 6>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 3 3 3 3 3 3 1 2 2 2 2 2Duff 10 10 11 11 11 11 7 7 7 8 8 8

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 4 4 4 4 4 4 4 4 4 4 4 4

Torching index Severe 18 28 14 25 38 54 35 60 73 79 92 101Crowning index Severe 11 11 11 11 11 12 16 16 15 15 15 15Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Active Cond. Cond. Cond. Cond. Surface Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 214 131 31 32 28 28 178 19 14 11 11 11

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 14 5 2 1 1 1 12 5 3 2 2 2

3–6 in 7 6 5 5 4 4 7 6 5 5 4 46–12 in 4 4 4 3 3 3 4 4 4 3 3 3>12 in 0 0 0 0 0 0 0 0 0 0 0 1Litter 5 1 1 1 1 1 4 1 1 1 2 2Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 5 3 3 3 3 3 4 2 1 1 1 1

Severe 6 5 5 4 4 4 5 3 2 1 1 1

Torching index Severe 37 24 36 45 47 47 52 121 303 624 694 793Crowning index Severe 45 49 51 53 55 57 28 31 33 34 35 36Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 201 111 5 6 5 5 202 112 7 7 8 8

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 1
F

64Table 6b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 1 1 1 1 3 2 2 2 2 2

3–6 in 2 2 2 2 2 1 2 2 2 2 2 26–12 in 1 1 1 1 1 1 1 1 1 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 1Litter 4 1 1 1 1 1 4 1 1 1 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 4 4 4 5 5 5 5 5 5

Torching index Severe 22 34 39 45 47 48 26 38 40 47 47 53

Crowning index Severe 45 49 51 53 55 57 28 31 33 34 35 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 201 111 6 6 6 6 202 112 7 8 8 9

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 1 1 1 0 2 1 1 1 1

3–6 in 2 2 2 2 2 1 2 2 2 2 2 26–12 in 2 3 3 3 3 2 2 4 4 4 4 4>12 in 0 0 0 0 1 1 0 0 0 0 1 1Litter 0 1 1 1 1 1 4 1 1 1 1 1Duff 7 7 7 7 7 7 9 7 7 7 7 7

Flame length (ft) Moderate 4 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 5 4 4 4 5 5 5 5

Torching index Severe 29 33 37 42 45 47 34 39 40 45 47 49Crowning index Severe 51 55 59 61 63 64 34 36 38 40 41 41Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 86 12 8 6 5 5 95 18 10 7 7 7

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 1
G

65

Table 6b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 9 5 4 3 3 4 7 5 5 5 5 5

3–6 in 7 6 5 5 5 4 7 6 6 5 5 56–12 in 4 4 4 4 4 4 4 4 4 4 4 5>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 4 2 2 2 2 2 3 2 2 2 3 3Duff 10 10 10 11 11 11 10 10 10 11 11 11

Flame length (ft) Moderate 3 2 2 2 2 2 2 3 3 3 3 3

Severe 4 3 3 2 2 2 3 4 4 4 4 4

Torching index Severe 82 159 302 450 535 562 82 63 76 89 103 106

Crowning index Severe 19 21 21 22 22 22 14 15 15 14 15 15Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 203 114 9 10 11 11 204 116 12 14 21 24

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 3 3 3 3 3 2 4 4 4 5 4

3–6 in 2 2 2 2 2 2 2 2 2 2 2 26–12 in 1 1 2 2 2 2 1 1 2 2 2 3>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 4 2 2 2 2 2 3 2 2 2 3 3Duff 9 9 9 9 9 10 9 9 9 10 10 10

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 5 4 4 4 4 4 4 4

Torching index Severe 30 48 58 69 76 85 40 57 69 83 95 103Crowning index Severe 19 21 21 21 22 22 14 15 15 14 15 15Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 203 114 9 10 11 12 204 116 12 15 21 24

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 1
H

66

Table 6c— Treatment effect on forest stand attributes, 50-year trajectory orest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 707 682 691 667 662 643 318 315 309 302 296 290

Quadratic mean diameter (in) 7.1 7.5 7.7 8.1 8.4 8.7 7.1 9.2 9.7 10.2 10.7 11.2Total volume (ft 3) 3,048 3,737 4,456 5,165 5,925 6,675 2,332 2,626 3,246 3,891 4,568 5,277Merchantable volume (ft 3) 2,035 2,683 3,302 3,994 4,722 5,391 1,741 1,970 2,537 3,097 3,841 4,521Basal area (ft 2) 195 211 226 239 253 266 137 144 159 172 185 198Stand density index 408 432 459 477 498 515 263 274 294 313 331 348Canopy closure (percent) 81 80 78 76 75 74 65 66 65 64 64 64Crown competition factor 281 294 310 323 337 347 187 194 207 219 230 241Canopy base height (ft) 6 8 5 7 10 14 12 17 24 28 34 38Canopy bulk density (kg/m3) 0.29 0.30 0.30 0.29 0.29 0.28 0.19 0.19 0.20 0.21 0.22 0.21

Table 6b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 2 2 2 3 0 4 3 3 3 3

3–6 in 2 3 3 3 3 3 2 4 4 4 3 36–12 in 2 5 6 5 5 5 2 7 7 6 6 6>12 in 0 0 0 0 1 1 0 0 0 0 0 1Litter 1 1 2 2 2 2 1 2 2 2 2 2Duff 7 7 7 7 7 8 7 7 7 7 8 8

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 5 5 5 4 4 4 4 4

Torching index Severe 27 35 44 49 59 68 31 47 55 64 75 84Crowning index Severe 23 26 27 27 27 27 19 20 20 20 20 20Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 103 19 12 9 9 10 114 20 13 10 11 12

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 1 — Lewis and Clark National Forest 1
I

67

Table 6c— Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 707 49 132 128 125 122 119 99 180 176 172 168 164

Quadratic mean diameter (in) 7.1 12.4 8.1 8.6 9.2 9.7 10.2 11.4 8.9 9.5 10.1 10.7 11.2Total volume (ft3) 3,048 843 956 1,204 1,474 1,764 2,069 1,396 1,585 1,995 2,442 2,912 3,401

Merchantable volume (ft3) 2,035 739 800 1,029 1,302 1,576 1,868 1,205 1,335 1,745 2,119 2,596 3,055Basal area (ft2) 195 42 47 52 57 63 68 70 79 87 96 105 113Stand density index 408 70 93 101 109 116 124 122 151 163 175 187 198

Canopy cover (percent) 81 22 25 27 29 31 33 37 40 42 44 46 47Crown competition factor 281 47 51 56 62 67 72 83 91 98 107 115 122Canopy base height (ft) 6 17 18 20 23 24 24 15 19 20 24 24 27

Canopy bulk density (kg/m3) 0.29 0.05 0.04 0.04 0.04 0.04 0.04 0.09 0.08 0.08 0.07 0.07 0.07

Pile and burn Trees per acre 707 49 140 136 133 130 127 99 189 184 180 176 172

Quadratic mean diameter (in) 7.1 12.4 7.8 8.4 8.9 9.4 9.9 11.4 8.7 9.3 9.9 10.5 11.0Total volume (ft3) 3,048 843 956 1,204 1,475 1,765 2,070 1,396 1,585 1,994 2,441 2,910 3,399

Merchantable volume (ft3) 2,035 739 800 1,029 1,302 1,576 1,866 1,205 1,335 1,745 2,119 2,596 3,055Basal area (ft2) 195 42 47 52 57 63 68 70 79 87 96 105 113Stand density index 408 70 94 102 110 118 125 122 152 165 177 189 200Canopy cover (percent) 81 22 25 27 29 31 33 37 40 42 44 46 47Crown competition factor 281 47 51 56 62 68 73 83 91 98 107 115 123Canopy base height (ft) 6 17 18 20 23 24 25 15 19 20 24 24 27Canopy bulk density (kg/m3) 0.29 0.05 0.04 0.04 0.04 0.04 0.04 0.09 0.08 0.08 0.07 0.07 0.07

Prescribed fire Trees per acre 707 49 139 136 132 129 126 99 176 172 168 164 160

Quadratic mean diameter (in) 7.1 12.4 7.1 7.7 8.2 8.7 9.2 11.4 8.1 8.7 9.3 9.8 10.4Total volume (ft3) 3,048 693 790 1,004 1,243 1,501 1,773 1,110 1,267 1,613 1,995 2,401 2,829Merchantable volume (ft3) 2,035 608 657 885 1,108 1,337 1,588 958 1,061 1,410 1,748 2,133 2,560Basal area (ft2) 195 42 39 43 48 53 58 70 63 71 78 86 94Stand density index 408 70 81 88 96 103 111 122 125 137 148 159 169Canopy cover (percent) 81 22 21 24 26 28 29 37 33 36 38 40 42

Crown competition factor 281 47 43 47 53 58 63 83 72 79 87 94 102Canopy base height (ft) 6 17 19 21 23 24 25 16 19 20 23 25 26Canopy bulk density (kg/m3) 0.29 0.04 0.04 0.03 0.03 0.03 0.03 0.07 0.07 0.06 0.06 0.06 0.06

Region 1 — Lewis and Clark National Forest 1
J

68Table 6c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 707 198 277 271 265 260 254 297 374 366 358 344 332

Quadratic mean diameter (in) 7.1 10.2 9.2 9.8 10.3 10.9 11.4 9.5 8.9 9.4 9.9 10.4 10.8Total volume (ft3) 3,048 2,176 2,467 3,087 3,756 4,462 5,191 2,700 3,039 3,742 4,463 5,133 5,833Merchantable volume (ft3) 2,035 1,831 2,072 2,641 3,282 3,960 4,627 2,241 2,509 3,155 3,866 4,462 5,198Basal area (ft2) 195 113 127 141 155 168 181 145 162 177 192 202 213Stand density index 408 205 241 261 280 298 314 272 310 333 353 365 378Canopy cover (percent) 81 55 56 56 57 57 58 67 67 67 67 67 67Crown competition factor 281 139 151 163 175 186 197 190 205 219 231 240 248

Canopy base height (ft) 6 13 20 24 29 33 38 13 20 26 32 37 40Canopy bulk density (kg/m3) 0.29 0.16 0.14 0.14 0.13 0.13 0.13 0.22 0.21 0.21 0.22 0.21 0.21

Pile and burn Trees per acre 707 198 286 279 273 267 262 297 383 374 365 351 339

Quadratic mean diameter (in) 7.1 10.2 9.0 9.6 10.2 10.7 11.2 9.5 8.8 9.3 9.8 10.3 10.7Total volume (ft3) 3,048 2,176 2,467 3,087 3,756 4,462 5,191 2,700 3,039 3,741 4,452 5,122 5,822Merchantable volume (ft3) 2,035 1,831 2,072 2,641 3,282 3,960 4,627 2,241 2,509 3,155 3,858 4,453 5,187Basal area (ft2) 195 113 127 141 155 168 181 145 162 177 191 202 212Stand density index 408 205 243 262 281 299 316 272 312 334 353 366 379Canopy cover (percent) 81 55 57 58 59 60 60 67 67 67 67 67 67Crown competition factor 281 139 151 163 175 187 197 190 205 219 231 239 248

Canopy base height (ft) 6 13 20 24 29 33 38 13 20 26 32 37 40Canopy bulk density (kg/m3) 0.29 0.16 0.14 0.14 0.13 0.13 0.13 0.22 0.21 0.21 0.22 0.21 0.21

Prescribed fire Trees per acre 707 198 243 237 232 227 222 297 304 297 290 284 278

Quadratic mean diameter (in) 7.1 10.2 8.5 9.2 9.8 10.3 10.9 9.5 8.5 9.0 9.6 10.1 10.6Total volume (ft3) 3,048 1,649 1,884 2,400 2,969 3,572 4,200 1,977 2,245 2,827 3,451 4,111 4,801

Merchantable volume (ft3) 2,035 1,392 1,582 2,063 2,594 3,164 3,795 1,649 1,862 2,391 2,986 3,614 4,272

Basal area (ft2) 195 113 97 109 121 133 144 145 118 132 145 158 170

Stand density index 408 205 189 206 224 240 255 272 232 252 271 289 305Canopy cover (percent) 81 55 48 50 52 53 54 67 57 58 59 60 61Crown competition factor 281 139 114 125 136 146 156 190 148 160 173 184 195Canopy base height (ft) 6 13 18 22 24 29 34 13 20 24 28 33 37Canopy bulk density (kg/m3) 0.29 0.12 0.10 0.10 0.10 0.10 0.10 0.16 0.15 0.14 0.14 0.14 0.14

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Lewis and Clark National Forest 1
K

69

Table 6d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 2 84 10 16 0 0 0 0 2 100 0 0 0 0 0 0

10 2 57 10 43 0 0 0 0 10 77 2 23 0 0 0 0

20 10 55 2 45 0 0 0 0 10 56 2 44 0 0 0 0

30 10 61 2 39 0 0 0 0 2 51 10 49 0 0 0 0

40 10 65 2 35 0 0 0 0 2 56 10 44 0 0 0 0

50 10 66 2 34 0 0 0 0 2 58 10 42 0 0 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 14 57 11 43 0 0 11 61 14 39 0 0

10 1 52 10 48 0 0 8 53 10 47 0 0

20 1 93 10 7 0 0 8 86 10 14 0 0

30 1 100 0 0 0 0 8 98 10 2 0 0

40 1 95 2 5 0 0 8 100 0 0 0 0

50 1 87 2 13 0 0 8 100 0 0 0 0

Pile and burn 1 1 68 10 32 0 0 0 0 1 50 2 28 0 0

10 1 100 0 0 0 0 0 0 1 51 2 49 0 0

20 1 100 0 0 0 0 0 0 2 61 1 39 0 0

30 1 100 0 0 0 0 0 0 2 71 1 29 0 0

40 1 94 2 6 0 0 0 0 2 79 1 21 0 0

50 1 86 2 14 0 0 0 0 2 84 1 16 0 0

Prescribed fire 1 1 100 0 0 0 0 0 0 1 97 2 3 0 0

10 1 100 0 0 0 0 0 0 1 83 2 17 0 0

20 1 100 0 0 0 0 0 1 70 2 30 0 0

30 1 100 0 0 0 0 0 1 59 2 41 0 0

40 1 100 0 0 0 0 0 2 50 1 50 0 0

50 1 100 0 0 0 0 0 2 58 1 42 0 0

Region 1 — Lewis and Clark National Forest 1
L

70

Region 1 — Lewis and Clark National Forest 1

Table 6d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 11 86 14 14 0 0 11 90 2 10

10 8 50 10 50 0 0 10 53 2 47

20 8 70 10 30 0 0 2 55 10 45

30 8 77 10 23 0 0 2 62 10 38

40 8 78 10 22 0 0 2 59 10 41

50 8 76 10 24 0 0 2 58 10 42

Pile and burn 1 2 100 0 0 0 0 2 100 0 0

10 2 100 0 0 0 0 2 95 10 5

20 2 100 0 0 0 0 2 86 10 14

30 2 100 0 0 0 2 84 10 16

40 2 96 10 4 0 0 2 78 10 22

50 2 92 10 8 0 0 2 74 10 26

Prescribed fire 1 2 75 1 25 0 0 2 100 0 0

10 2 74 10 17 1 9 2 59 10 41

20 2 90 10 10 0 0 2 71 10 29

30 2 93 10 7 0 0 2 75 10 25

40 2 92 10 8 0 0 2 77 10 23

50 2 90 10 10 0 0 2 76 10 24

tpa = trees per acre; d.b.h. = diameter at breast height.Table 6f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 6e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 16 80 4 6 15 16 50 100Moderate—75th percentile 11 65 6 9 18 25 125 150
Initial stand conditions

A

71

Site: Elevation = 5,600 ft, slope = 25 percent, aspect = 360°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 92 percent, hardwoods = 6 percent, ponderosa pine (Pinus ponderosa) = 1 percent, lodgepole pine (Pinus contorta) = 1 percent.

Stand attributes: Stem density = 6,573 tpa, basal area = 172 ft2/ac, top height = 54 ft, stand density index = 575, quadratic mean diameter = 2.2 in, crown competition factor = 243, canopy cover = 69 percent. 

Region 1 — Lewis and Clark National Forest 2
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

72

Region 1 — Lewis and Clark National Forest 2
C

73

Initial conditions/no-action trajectoryThis stand has extremely high initial tree density of6,573 trees per acre (tpa) composed mostly of Douglas-fir with some hardwoods in the understory and

ponderosa pine and lodgepole pine in the overstory.The Stand top height is only 54 ft and there are manyseedlings. Woody surface fuel loading is 9 tons/acand litter and duff loading is 13 tons/ac. Canopy baseheight is 14 ft and canopy bulk density is 0.21 kg/m3

(0.0131 lb/ft3), so initially ladder fuels are not sufficient

to enable passive crown fire crown, but crown firespread is possible under severe fire weather. Potentialbasal area mortality is about 30 percent for moderateand severe fire weather, likely because the stand isdominated by fire-resistant conifer species. With noaction, canopy base height declines and canopy bulkdensity increases as smaller trees grow into the canopy;active crown fire is predicted in 10 years. Surfacefuels accumulate over time but flame lengths remain

constant.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment kills many smalltrees, which raises canopy base height and reducescrown fire potential. Many snags are created, but theyare generally small and the contributions to futuresurface fuel loading are minor. All thinning treatmentsreduce canopy bulk density and increase canopy baseheight; the greater the thinning, the greater is thechange in forest structure. However, thinning to 200tpa or less is necessary to prevent conditional crownfire. All thinning treatments generate activity fuels, andthese surface fuels are sufficient to increase potentialflame lengths in the 50 tpa treatment. The pile andburn treatment reduces woody fuel loading to belowinitial conditions, and the prescribed fire treatmentreduces woody fuel loading even more and consumessome of the duff layer. However, these changes insurface fuel loading do not decrease potential flamelengths and basal area mortality because the openedstands with low woody fuel loading are characterized by fuel model 2, which typically has high flame

lengths. Grass fuels are not tracked in FFE and may ormay not be an important contributor to fire behaviorfollowing surface fuel treatments.

Silvicultural and surface fuel treatments—long-term effectsThe 50 tpa treatment has a long-term effect on crownfire potential with the predicted fire type remainingsurface fire for the 50-year projection. Regenerationcauses a drop in canopy base height in 30 or 40 years,but at this time, potential flame lengths are sufficientlylow that passive crown fire is prevented. The 100tpa and 200 tpa treatments have less of a long-termeffect on crown fire potential. Flame lengths decreaseas surface fuels decompose, but passive crown firebecomes likely again for severe fire weather in 30 or40 years when regeneration lowers canopy base height.Canopy bulk density remains high enough in the 300tpa treatment that conditional crown fire is predictedfor the 50-year projection. However, if a prescribedfire surface fuel treatment is applied, fire-caused treemortality reduces canopy bulk density enough thatconditional crown fire is eliminated.

Region 1 — Lewis and Clark National Forest 2
D

74Table 7a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 10 8 6 4

3–6 in 3 0 4 4 4 46–12 in 3 2 3 3 3 3>12 in 0 0 0 0 0 0Litter 3 1 4 4 3 3Duff 10 7 10 10 10 10

Flame length (ft) Moderate 3 3 4 3 3 3

Severe 4 5 5 4 4 4

Torching index Severe 42 44 117 196 51 27Crowning index Severe 15 20 48 28 17 16Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Surface Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 29 26 19 20 25 27

Severe 33 38 19 20 25 30

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 4 4 3 3Duff 9 9 9 9

Flame length (ft) Moderate 3 3 3 3

Severe 5 4 5 5

Torching index Severe 36 49 50 51Crowning index Severe 48 28 17 16Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 19 20 25 27

Severe 19 20 31 37

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 2 2 2 2>12 in 0 0 0 0Litter 0 1 1 1Duff 7 7 7 7

Flame length (ft) Moderate 4 3 3 3

Severe 5 5 4 5

Torching index Severe 40 49 51 42Crowning index Severe 55 32 21 20Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 16 18 22 25

Severe 18 18 24 34

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 1 — Lewis and Clark National Forest 2
E

75

Table 7b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 5 6 6 6 7 1 5 3 2 2 3

3–6 in 3 4 4 4 5 5 0 4 4 4 3 36–12 in 3 4 5 6 8 9 2 7 8 8 7 7>12 in 0 0 0 1 1 2 0 0 1 1 1 1Litter 3 3 3 3 4 4 1 2 2 2 2 2Duff 10 10 10 11 11 11 7 7 7 8 8 8

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 4 4 4 4 4 4 5 5 4 4 4 4

Torching index Severe 42 0 9 10 10 13 44 54 55 60 11 11Crowning index Severe 15 16 16 16 7 5 20 19 19 19 19 19Type of fire Moderate Surface Passive Surface Surface Cond. Cond. Surface Surface Surface Surface Surface Surface

Severe Cond. Active Passive Passive Active Active Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 287 436 551 560 519 484 1,629 28 18 14 15 15

18–29.9 in 0 0 0 1 1 1 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 10 4 2 1 1 1 8 4 2 1 1 2

3–6 in 4 4 4 4 3 3 4 4 4 4 3 36–12 in 3 4 4 3 3 3 3 4 4 4 3 3>12 in 0 0 0 0 0 1 0 0 0 0 1 1Litter 4 1 1 1 1 1 4 1 1 1 1 2Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 4 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 4 4 4 4 5 5 5 5 5

Torching index Severe 117 36 52 54 18 19 196 44 56 15 15 19Crowning index Severe 48 49 50 52 54 57 28 29 30 32 33 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 37 25 7 6 6 6 38 26 9 9 9 9

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 2
F

76Table 7b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 1 1 1 1 2 2 1 1 1 1

3–6 in 1 2 2 2 1 1 1 2 2 2 2 26–12 in 1 1 2 2 2 2 1 2 2 2 2 2>12 in 0 0 0 0 0 1 0 0 0 0 1 1Litter 4 1 1 1 1 1 4 1 1 1 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 4 4 4 4 4 5 5 5 5

Torching index Severe 36 47 52 17 18 19 49 53 56 15 15 17Crowning index Severe 48 49 50 52 54 57 28 28 30 32 33 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 37 25 7 7 6 6 38 26 9 9 9 9

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 1 1 1 0 2 1 1 1 1

3–6 in 1 2 2 2 2 2 1 2 2 2 2 26–12 in 2 3 4 4 3 3 2 4 5 5 5 4>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 0 1 1 1 1 1 4 1 1 1 1 1Duff 7 7 7 7 7 7 9 7 7 7 7 7

Flame length (ft) Moderate 4 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 4 4 5 4 4 4 5 5

Torching index Severe 40 44 49 14 17 17 49 54 56 14 16 18Crowning index Severe 55 56 56 58 61 62 32 33 35 36 38 38Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 30 17 10 7 6 6 39 24 14 9 9 9

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 2
G

77

Table 7b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 6 4 3 2 2 3 4 4 3 3 4 4

3–6 in 4 4 4 4 3 3 4 4 4 4 4 36–12 in 3 4 4 4 4 4 3 4 4 4 4 4>12 in 0 0 0 0 1 1 0 0 0 0 0 1Litter 3 2 2 2 2 2 3 2 2 2 3 3Duff 10 10 10 10 10 11 10 10 10 10 11 11

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 4 5 5 5 4 4 4 4 4 4 4 4

Torching index Severe 51 55 61 73 80 84 27 57 67 76 85 92Crowning index Severe 17 18 19 19 20 20 16 16 16 15 15 16Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 39 27 11 11 11 12 40 29 14 14 16 20

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 2 2 2 3 1 3 3 3 4 4

3–6 in 1 2 2 2 2 2 1 2 2 2 2 26–12 in 1 2 2 2 3 3 1 2 2 2 3 3>12 in 0 0 0 0 1 1 0 0 0 0 0 1Litter 3 2 2 2 2 2 3 2 2 2 3 3Duff 9 9 9 9 9 9 9 9 9 9 10 10

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 5 4 5 4 4 4 4 4

Torching index Severe 50 60 65 76 20 20 51 61 71 78 84 94Crowning index Severe 17 18 18 19 20 21 16 16 15 15 15 16Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Cond. Cond. Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 39 27 11 11 12 12 40 29 14 14 17 21

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 1 — Lewis and Clark National Forest 2
H

78

Table 7c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 6,573 6,079 5,734 5,263 4,825 4,420 348 381 434 424 419 410

Quadratic mean diameter (in) 2.2 2.3 2.4 2.5 2.7 2.8 2.2 8 7.8 8.2 8.6 9Total volume (ft 3) 3,105 3,451 3,760 4,055 4,317 4,555 2,466 2,694 3,191 3,750 4,360 5,004Merchantable volume (ft 3) 2,418 2,824 3,106 3,381 3,675 3,922 2,002 2,239 2,690 3,228 3,826 4,447Basal area (ft 2) 172 176 178 182 186 190 127 133 144 156 168 181Stand density index 575 575 575 575 575 575 252 266 291 309 328 346Canopy closure (percent) 68 68 71 75 77 78 50 52 57 61 64 65Crown competition factor 243 244 253 264 274 292 168 173 184 196 209 223Canopy base height (ft) 14 3 4 4 4 5 21 24 24 25 5 5Canopy bulk density (kg/m3) 0.21 0.20 0.19 0.19 0.50 0.64 0.15 0.15 0.15 0.15 0.15 0.15

Table 7b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 2 2 2 2 0 4 3 2 2 3

3–6 in 1 3 3 3 3 3 1 4 4 4 3 36–12 in 2 6 7 7 6 6 2 7 8 8 7 7>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 1 1 1 2 2 2 1 2 2 2 2 2Duff 7 7 7 7 7 7 7 7 7 7 8 8

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 3

Severe 4 5 5 5 5 5 5 5 5 4 4 4

Torching index Severe 51 48 52 59 14 15 42 47 55 63 71 16Crowning index Severe 21 21 23 23 24 26 20 20 20 20 20 20Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 51 27 16 10 10 10 62 28 17 12 12 12

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 1 — Lewis and Clark National Forest 2
I

79

Table 7c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 6,573 50 161 157 153 150 146 100 210 205 200 195 191

Quadratic mean diameter (in) 2.2 13.6 7.9 8.4 8.8 9.3 9.7 12.5 9.0 9.4 9.9 10.4 10.9Total volume (ft3) 3,105 1,137 1,244 1,475 1,728 1,999 2,280 1,900 2,071 2,441 2,847 3,287 3,747Merchantable volume (ft3) 2,418 980 1,085 1,291 1,552 1,808 2,054 1,616 1,813 2,154 2,534 2,951 3,382Basal area (ft2) 172 51 55 60 65 70 75 85 92 99 107 115 123Stand density index 575 82 111 118 125 133 140 143 176 186 197 207 218Canopy cover (percent) 68 20 23 26 28 30 32 32 36 39 42 44 46Crown competition factor 243 59 63 67 73 79 85 101 106 113 121 129 137Canopy base height (ft) 14 28 29 31 31 7 8 28 29 31 7 7 9Canopy bulk density (kg/m3) 0.21 0.05 0.04 0.04 0.04 0.04 0.04 0.10 0.09 0.09 0.08 0.07 0.07

Pile and burn Trees per acre 6,573 50 172 167 163 159 156 100 221 215 210 205 201

Quadratic mean diameter (in) 2.2 13.6 7.7 8.1 8.6 9.0 9.4 12.5 8.7 9.2 9.7 10.1 10.6Total volume (ft3) 3,105 1,137 1,244 1,476 1,729 2,001 2,283 1,900 2,071 2,442 2,849 3,287 3,748Merchantable volume (ft3) 2,418 980 1,085 1,291 1,552 1,808 2,054 1,616 1,813 2,154 2,530 2,944 3,390Basal area (ft2) 172 51 55 60 65 70 76 85 92 99 107 115 123Stand density index 575 82 112 119 127 135 142 143 178 188 199 210 221Canopy cover (percent) 68 20 23 26 28 31 32 32 36 39 42 45 47Crown competition factor 243 59 63 68 74 80 85 101 107 113 122 130 138Canopy base height (ft) 14 28 29 31 7 7 8 28 29 31 7 7 8Canopy bulk density (kg/m3) 0.21 0.05 0.04 0.04 0.04 0.04 0.04 0.10 0.09 0.09 0.08 0.08 0.07

Prescribed fire Trees per acre 6,573 50 173 168 164 160 156 100 211 206 201 196 192

Quadratic mean diameter (in) 2.2 13.6 6.9 7.4 7.8 8.2 8.7 12.5 8 8.5 9.0 9.4 9.9Total volume (ft3) 3,105 938 1,032 1,239 1,467 1,712 1,968 1,538 1,687 2,010 2,367 2,752 3,162Merchantable volume (ft3) 2,418 810 905 1,082 1,314 1,554 1,769 1,311 1,480 1,772 2,104 2,471 2,842Basal area (ft2) 172 51 45 50 54 59 64 85 74 81 88 95 103Stand density index 575 82 96 103 110 117 125 143 149 158 169 179 189Canopy cover (percent) 68 20 20 22 25 27 29 32 30 34 37 39 42Crown competition factor 243 59 50 55 61 66 72 101 85 91 99 107 114Canopy base height (ft) 14 28 29 31 6 7 7 28 29 31 6 7 8Canopy bulk density (kg/m3) 0.21 0.04 0.04 0.04 0.04 0.03 0.03 0.08 0.08 0.07 0.07 0.06 0.06

Region 1 — Lewis and Clark National Forest 2
J

80

Table 7c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 6,573 200 308 301 295 289 283 300 406 397 389 380 368

Quadratic mean diameter (in) 2.2 10.9 9.1 9.5 9.9 10.4 10.8 9.8 8.8 9.2 9.6 10.0 10.4Total volume (ft3) 3,105 2,723 2,945 3,421 3,950 4,513 5,101 3,183 3,451 4,027 4,649 5,283 5,880Merchantable volume (ft3) 2,418 2,285 2,512 2,970 3,457 3,984 4,532 2,616 2,905 3,430 4,033 4,653 5,183Basal area (ft2) 172 129 138 148 159 169 180 159 170 183 195 207 217Stand density index 575 229 264 277 292 306 319 292 329 347 364 380 391Canopy cover (percent) 68 47 50 54 56 58 59 57 61 64 65 66 67Crown competition factor 243 164 172 181 191 201 211 213 224 236 248 260 268Canopy base height (ft) 14 25 28 30 34 37 41 21 24 27 30 33 37Canopy bulk density (kg/m3) 0.21 0.18 0.16 0.16 0.16 0.15 0.14 0.20 0.20 0.20 0.20 0.21 0.20

Pile and burn Trees per acre 6,573 200 319 312 306 299 293 300 417 408 399 389 377

Quadratic mean diameter (in) 2.2 10.9 8.9 9.3 9.8 10.2 10.6 9.8 8.7 9.1 9.5 9.9 10.3Total volume (ft3) 3,105 2,723 2,945 3,421 3,950 4,512 5,100 3,183 3,451 4,027 4,648 5,269 5,865Merchantable volume (ft3) 2,418 2,285 2,512 2,970 3,456 3,984 4,527 2,616 2,905 3,430 4,033 4,639 5,170Basal area (ft2) 172 129 138 148 159 169 180 159 170 183 195 207 216Stand density index 575 229 266 279 294 308 322 292 331 348 366 381 393Canopy cover (percent) 68 47 50 54 56 58 59 57 61 63 65 66 67Crown competition factor 243 164 172 181 192 202 211 213 224 236 249 259 268Canopy base height (ft) 14 25 29 30 34 8 8 21 24 27 30 33 37Canopy bulk density (kg/m3) 0.21 0.18 0.17 0.16 0.16 0.15 0.14 0.20 0.20 0.20 0.21 0.21 0.20

Prescribed fire Trees per acre 6,573 200 275 269 263 257 252 300 334 327 319 312 306

Quadratic mean diameter (in) 2.2 10.9 8.4 8.8 9.3 9.7 10.2 9.8 8.3 8.7 9.2 9.6 10.1Total volume (ft3) 3,105 2,084 2,272 2,678 3,133 3,625 4,146 2,363 2,583 3,064 3,594 4,164 4,763Merchantable volume (ft3) 2,418 1,757 1,949 2,335 2,745 3,193 3,735 1,959 2,190 2,638 3,128 3,656 4,272Basal area (ft2) 172 129 105 114 123 132 142 159 125 135 147 158 169Stand density index 575 229 207 219 232 245 258 292 246 262 278 294 309Canopy cover (percent) 68 47 41 45 48 51 53 57 50 53 56 58 60Crown competition factor 243 164 128 136 145 154 163 213 159 170 181 192 203Canopy base height (ft) 14 27 29 30 32 7 7 21 23 26 29 32 7Canopy bulk density (kg/m3) 0.21 0.14 0.13 0.13 0.12 0.11 0.11 0.15 0.15 0.15 0.15 0.15 0.15

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 1 — Lewis and Clark National Forest 2
K

81

Table 7d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 2 91 10 9 2 92 1 8

10 2 62 10 38 2 53 10 47

20 10 53 2 47 2 65 10 35

30 10 71 2 29 2 74 10 26

40 10 90 2 10 2 78 10 22

50 10 92 12 8 2 75 10 25

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 11 82 14 18 11 99 14 1 0 0

10 1 78 10 22 1 56 2 23 10 22

20 1 100 0 0 1 54 2 45 10 1

30 1 100 0 0 2 61 1 39 0 0

40 1 99 2 1 2 73 1 27 0 0

50 1 90 2 10 2 82 1 18 0 0

Pile and burn 1 1 85 10 15 1 85 2 11 10 5

10 1 100 0 0 1 71 2 29 0 0

20 1 100 0 0 1 53 2 47 0 0

30 1 100 0 0 2 62 1 38 0 0

40 1 97 2 3 2 74 1 26 0 0

50 1 88 2 12 2 84 1 16 0 0

Prescribed fire 1 1 100 0 0 1 100 0 0 0 0

10 1 100 0 0 1 98 2 2 0 0

20 1 100 0 0 1 81 2 19 0 0

30 1 100 0 0 1 65 2 35 0 0

40 1 100 0 0 1 53 2 47 0 0

50 1 100 0 0 2 58 1 42 0 0

Region 1 — Lewis and Clark National Forest 2
L

82

Region 1 — Lewis and Clark National Forest 2

Table 7d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 11 65 2 29 1 6 2 67 11 33 0 0

10 2 78 10 22 0 0 2 76 10 24 0 0

20 2 90 10 10 0 0 2 81 10 19 0 0

30 2 94 10 6 0 0 2 79 10 21 0 0

40 2 94 10 6 0 0 2 76 10 24 0 0

50 2 89 10 11 0 0 2 69 10 31 0 0

Pile and burn 1 2 84 1 16 0 0 2 100 0 0 0 0

10 2 100 0 0 0 0 2 100 0 0 0 0

20 2 100 0 0 0 0 2 100 0 0 0 0

30 2 100 0 0 0 0 2 95 10 5 0 0

40 2 100 0 0 0 0 2 88 10 12 0 0

50 2 100 0 0 0 2 80 10 20 0 0

Prescribed fire 1 1 64 2 36 0 0 2 74 1 26 0 0

10 2 49 1 37 10 14 2 63 10 36 1 1

20 2 65 1 21 10 13 2 70 10 30 0 0

30 2 82 10 10 1 8 2 75 10 25 0 0

40 2 93 10 7 0 0 2 77 10 23 0 0

50 2 92 10 8 0 0 2 76 10 24 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.Table 7f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 7e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 16 80 4 5 10 15 50 100Moderate—75th percentile 11 69 12 12 14 25 125 150
Initial stand conditions

A

83

Appendix 3—Fuel Treatment Scenarios for the Southwestern Region (Region 3)

Site: Elevation = 9,200 ft, slope = 20 percent, aspect = 45°.Species (based on trees per acre): White fir (Abies concolor) = 65 percent, Douglas-fir (Pseudotsuga menziesii) = 27 percent, ponderosa pine (Pinus ponderosa) = 5 percent.

Stand attributes: Stem density = 384 tpa, basal area = 80 ft2/ac, top height = 50 ft, 

stand density index = 177, quadratic mean diameter = 6.2 in, crown competition factor = 77, canopy cover = 54 percent.

Region 3 — Carson National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

84

Region 3 — Carson National Forest 1
C

85

Initial conditions/no-action trajectoryThis stand has 384 trees per acre (tpa) composed ofDouglas-fir and white fir understory with a low-densityponderosa pine overstory. Canopy bulk density is 0.07kg/m3 (0.0044 lb/ft3), and canopy base height is 2 ft,

so ladder fuels are sufficient to enable passive crownfire, but canopy fuels are not sufficient to enable activecrown fire for severe fire weather. Woody fuel loadingis 6 tons/ac, and litter and duff loading is 6 tons/ac.Predicted flame lengths are low for severe and moderate fire weather, but potential basal area mortality is 87

percent for severe fire weather. With no action, canopybase height remains low, canopy bulk density increasesas smaller trees grow into the overstory, and surfacefuels accumulate over time causing higher potentialflame lengths. In 20 years, passive crown fire becomeslikely for moderate and severe fire weather.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopybase height and decreases canopy bulk density andsurface fuel loading. Potential flame lengths for severefire weather increase to 5 ft, and passive crown fireremains likely because brush grows, and fire behavioris predicted by using fuel model 5. Brush fuels arenot tracked in FFE, and the influences of brush fuelsfollowing treatment are site specific. Thinning to 100tpa or less is required to increase canopy base heightand reduce canopy bulk density sufficiently to affectcrown fire potential. All thinning treatments increasesurface fuels that contribute to higher potential flamelengths. The pile and burn and prescribed fire surfacefuel treatments reduce woody surface fuels to belowinitial levels, and this reduces potential flame lengthsand basal area mortality in the more dense treatments.However, potential flame lengths and basal area mortality remain high in the 50 tpa treatment regardless

of surface fuel treatment, and in the 100 and 200 tpatreatments with a prescribed fire, because fire behavioris driven by brush fuel models.

Silvicultural and surface fuel treatments—long-term effectsAlthough the prescribed fire only treatment does notreduce crown fire potential initially, in 10 years, crownfire potential decreases and surface fire is predictedfor moderate and severe fire weather. Flame lengthsdecrease over time as brush fuels decrease and canopybase height continues to increase, so crown firepotential declines over the 50-year trajectory. Thinningto 50 to 100 tpa has a long-term effect on crown firepotential. The predicted fire type in these treatmentsis surface fire for 50 years, and flame lengths decreaseover time as brush fuels decrease. Canopy base heightincreases over time in the higher density treatments(200, 300 tpa), but the stands remain susceptibleto passive crown fire for 50 years. However, in thehigh-density treatments, the prescribed fire surface fueltreatment further increases canopy base height becauseadditional understory trees are killed. This decreasescrown fire potential, and the predicted fire type issurface fire for 50 years.

Region 3 — Carson National Forest 1
D

86Table 8a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 2 1 4 3 3 2

3–6 in 2 0 2 2 2 26–12 in 2 1 2 2 2 2>12 in 0 0 0 0 0 0Litter 2 0 3 2 2 2Duff 4 3 4 4 4 4

Flame length (ft) Moderate 2 1 2 2 2 2

Severe 3 5 5 3 3 3

Torching index Severe 7 11 29 23 7 7Crowning index Severe 37 43 43 37 37 37Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 18 15 12 17 18 18

Severe 87 96 46 23 88 87

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 2 2 2 2Duff 4 4 4 4

Flame length (ft) Moderate 1 2 2 2

Severe 5 3 3 3

Torching index Severe 24 28 8 8Crowning index Severe 43 37 37 37Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 12 16 18 18

Severe 60 21 83 83

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 1 1 1 1>12 in 0 0 0 0Litter 0 0 0 0Duff 3 3 3 3

Flame length (ft) Moderate 1 1 1 1

Severe 6 5 5 5

Torching index Severe 23 11 11 11Crowning index Severe 48 43 43 43Type of fire Moderate Surface Surface Surface Surface

Severe Surface Passive Passive Passive

Potential basal area mortality (%) Moderate 12 15 15 15

Severe 65 96 96 96

tpa = trees per acre; d.b.h. = diameter at breast height. 

Region 3 — Carson National Forest 1
E

87

Table 8b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 2 2 3 3 3 4 1 2 2 2 2 2

3–6 in 2 2 2 2 2 2 0 1 1 1 1 16–12 in 2 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 0 0 1 1 0 0 1 1 1 1Litter 2 3 3 4 4 5 0 2 2 2 2 2Duff 4 5 5 5 5 5 3 3 3 3 3 3

Flame length (ft) Moderate 2 2 2 2 2 2 1 1 1 2 2 2

Severe 3 3 3 3 4 4 5 5 5 3 3 3

Torching index Severe 7 6 0 0 0 3 11 23 24 59 67 67Crowning index Severe 37 34 29 25 22 19 43 44 41 41 39 37Type of fire Moderate Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 5 7 9 10 10 10 76 5 3 2 2 2

18–29.9 in 0 0 0 0 1 1 1 1 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 3 3 2 2 2 3 3 2 3 3 3

3–6 in 2 2 2 2 2 2 2 2 2 2 2 26–12 in 2 2 2 2 2 2 2 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 3 2 2 2 2 2 2 2 3 3 3 3Duff 4 5 5 5 5 5 4 5 5 5 5 5

Flame length (ft) Moderate 2 2 1 2 2 2 2 2 2 1 1 1

Severe 5 5 5 3 3 3 3 3 3 2 2 2

Torching index Severe 29 26 30 69 71 66 23 37 43 196 213 218Crowning index Severe 43 44 43 42 40 39 37 36 34 32 31 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 2 2 2 2 2 2 2 2 3 3 3

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 1
F

88Table 8b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 2 2 2 2 1 1 2 2 2 3

3–6 in 1 1 1 1 1 1 1 1 1 1 1 16–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 2 2 2 2 2 2 2 3 3 3 3Duff 4 4 4 4 4 4 4 4 4 4 4 4

Flame length (ft) Moderate 1 1 1 2 2 2 2 2 2 1 1 1

Severe 5 5 5 3 3 3 3 3 3 1 1 1

Torching index Severe 24 25 29 72 75 72 28 43 51 307 349 318Crowning index Severe 43 42 40 42 40 39 37 36 33 32 31 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 2 2 2 2 2 2 2 2 3 3 3

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 2 2 2 0 2 2 2 2 2

3–6 in 0 0 1 1 1 1 1 1 1 1 1 16–12 in 1 1 2 2 2 2 1 2 2 2 2 2>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 0 1 2 2 2 2 2 2 2 2 2 3Duff 3 3 3 3 3 3 4 3 3 3 3 4

Flame length (ft) Moderate 1 1 1 1 1 2 1 1 1 2 2 2

Severe 6 5 5 5 5 3 5 5 5 3 3 3

Torching index Severe 23 24 25 31 33 33 11 23 24 59 67 65Crowning index Severe 48 45 42 41 40 40 43 41 39 36 36 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 8 5 4 3 2 2 15 5 3 2 2 2

18–29.9 in 1 1 0 0 0 0 1 1 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 1
G

89

Table 8b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 2 3 3 3 3 2 2 3 3 3 4

3–6 in 2 2 2 2 2 2 2 2 2 2 2 26–12 in 2 2 2 2 2 2 2 2 2 2 2 2>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 2 3 3 4 4 4 2 3 3 4 4 5Duff 4 5 5 5 5 5 4 5 5 5 5 5

Flame length (ft) Moderate 2 2 2 2 3 2 2 2 2 2 2 2

Severe 3 3 3 3 4 4 3 3 3 3 4 4

Torching index Severe 7 6 6 13 10 17 7 6 5 4 11 18Crowning index Severe 37 34 32 30 27 25 37 34 30 26 23 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Passive Surface Passive Passive Passive Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 3 4 6 7 7 6 5 6 7 9 9 8

18–29.9 in 0 0 0 0 0 1 0 0 0 0 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 2 2 3 3 1 1 2 2 3 3

3–6 in 1 1 1 1 1 1 1 1 1 1 1 16–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 2 3 3 4 4 4 2 3 3 4 4 5Duff 4 4 4 4 4 5 4 4 4 4 4 5

Flame length (ft) Moderate 2 2 2 2 3 2 2 2 2 2 2 2

Severe 3 3 3 3 4 4 3 3 2 3 4 4

Torching index Severe 8 9 9 18 10 24 8 9 10 8 11 25Crowning index Severe 37 34 32 30 27 24 37 34 30 26 23 20Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Surface Passive Surface Passive Passive Passive Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 3 4 6 7 7 6 5 6 7 9 9 8

18–29.9 in 0 0 0 0 0 1 0 0 0 0 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 1
H

90

Table 8c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 384 375 367 360 352 344 66 66 65 64 63 63

Quadratic mean diameter (in) 6.2 6.7 7.2 7.7 8.2 8.7 6.2 14.4 15.4 16.3 17.2 18.0Total volume (ft 3) 1,337 1,567 1,799 2,021 2,254 2,515 1,225 1,329 1,530 1,735 1,938 2,135Merchantable volume (ft 3) 1,150 1,349 1,508 1,687 1,868 2,087 1,083 1,184 1,358 1,560 1,760 1,955Basal area (ft 2) 80 92 104 116 129 143 70 75 84 93 102 111Stand density index 177 197 217 236 256 277 112 118 130 141 151 161Canopy closure (percent) 54 59 64 69 73 77 46 48 51 55 57 60Crown competition factor 77 88 102 117 132 148 62 65 72 79 85 91Canopy base height (ft) 2 2 1 1 2 3 6 10 10 10 11 11Canopy bulk density (kg/m3) 0.07 0.07 0.09 0.11 0.13 0.16 0.05 0.05 0.06 0.06 0.06 0.07

Table 8b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 2 2 0 2 2 2 2 2

3–6 in 0 1 1 1 1 1 0 1 1 1 1 16–12 in 1 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 0 2 2 2 2 3 0 2 2 2 2 3Duff 3 3 3 3 3 4 3 3 3 3 3 4

Flame length (ft) Moderate 1 1 1 2 2 2 1 1 1 2 2 2

Severe 5 5 5 3 3 3 5 5 5 3 3 3

Torching index Severe 11 23 24 59 67 71 11 23 24 59 67 70Crowning index Severe 43 43 40 38 36 34 43 43 39 37 36 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 36 5 3 2 2 2 57 5 3 2 2 2

18–29.9 in 1 1 0 0 0 0 1 1 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Carson National Forest 1
I

91

Table 8c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 384 50 64 63 63 62 61 100 107 105 104 102 101

Quadratic mean diameter (in) 6.2 15.5 14.5 15.4 16.2 17.0 17.8 12 12.4 13.2 14.0 14.7 15.5Total volume (ft3) 1,337 1,269 1,368 1,552 1,737 1,916 2,092 1,432 1,548 1,779 2,010 2,245 2,479Merchantable volume (ft3) 1,150 1,135 1,230 1,409 1,590 1,765 1,938 1,258 1,370 1,563 1,784 2,010 2,244Basal area (ft2) 80 65 74 82 90 97 105 78 89 100 111 121 131Stand density index 177 101 117 127 136 145 153 134 150 164 178 190 203Canopy cover (percent) 54 44 47 49 52 54 57 52 55 59 63 65 68Crown competition factor 77 57 63 68 73 78 83 72 81 89 98 106 113Canopy base height (ft) 2 11 11 12 13 13 12 5 7 8 9 10 11Canopy bulk density (kg/m3) 0.07 0.05 0.05 0.05 0.06 0.06 0.06 0.07 0.07 0.08 0.08 0.08 0.09

Pile and burn Trees per acre 384 50 72 71 70 70 69 100 111 109 108 106 105

Quadratic mean diameter (in) 6.2 15.5 13.7 14.5 15.3 16.0 16.8 12.0 12.2 13.0 13.7 14.5 15.2Total volume (ft3) 1,337 1,269 1,368 1,552 1,739 1,920 2,097 1,432 1,548 1,779 2,010 2,247 2,482Merchantable volume (ft3) 1,150 1,135 1,230 1,409 1,590 1,766 1,940 1,258 1,370 1,563 1,784 2,011 2,246Basal area (ft2) 80 65 74 82 90 98 105 78 89 100 111 121 132Stand density index 177 101 120 129 139 148 157 134 151 165 179 192 205Canopy cover (percent) 54 44 47 49 52 54 57 52 55 59 63 65 68Crown competition factor 77 57 63 68 73 79 84 72 81 89 98 106 114Canopy base height (ft) 2 11 11 12 13 13 12 5 7 8 9 10 11Canopy bulk density (kg/m3) 0.07 0.05 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.08 0.08 0.08 0.09

Prescribed fire Trees per acre 384 50 87 86 85 84 83 100 89 88 87 86 85

Quadratic mean diameter (in) 6.2 15.5 11.7 12.4 13.1 13.8 14.5 12.0 12.4 13.2 14.0 14.7 15.5Total volume (ft3) 1,337 1,121 1,211 1,381 1,556 1,724 1,892 1,225 1,332 1,534 1,741 1,946 2,147Merchantable volume (ft3) 1,150 1,003 1,090 1,256 1,422 1,584 1,748 1,084 1,187 1,363 1,564 1,764 1,960Basal area (ft2) 80 65 65 72 80 87 94 78 75 84 93 102 111Stand density index 177 101 112 121 131 141 150 134 126 138 150 161 172Canopy cover (percent) 54 44 42 45 48 50 53 52 48 51 55 58 60Crown competition factor 77 57 55 59 64 70 75 72 65 72 80 86 92Canopy base height (ft) 2 11 11 11 13 13 12 6 10 10 10 11 12Canopy bulk density (kg/m3) 0.07 0.05 0.05 0.06 0.06 0.06 0.06 0.05 0.06 0.06 0.07 0.07 0.07

Region 3 — Carson National Forest 1
J

92Table 8c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 384 200 200 196 191 187 183 300 297 291 284 278 272

Quadratic mean diameter (in) 6.2 8.5 9.1 9.8 10.4 11.1 11.7 7.0 7.5 8.1 8.7 9.2 9.8Total volume (ft3) 1,337 1,449 1,556 1,779 2,002 2,234 2,471 1,463 1,573 1,799 2,024 2,265 2,520Merchantable volume (ft3) 1,150 1,253 1,352 1,525 1,720 1,917 2,175 1,252 1,353 1,519 1,707 1,897 2,141Basal area (ft2) 80 80 91 102 114 125 137 80 92 104 116 129 142Stand density index 177 155 173 189 205 220 235 169 189 207 226 244 263Canopy cover (percent) 54 53 58 62 66 70 73 54 59 64 68 73 76Crown competition factor 77 76 86 97 109 120 130 77 89 101 115 129 143Canopy base height (ft) 2 2 2 2 3 4 6 2 2 2 2 4 6Canopy bulk density (kg/m3) 0.07 0.07 0.07 0.08 0.09 0.10 0.12 0.07 0.07 0.09 0.11 0.13 0.15

Pile and burn Trees per acre 384 200 202 198 193 189 185 300 299 293 286 280 274

Quadratic mean diameter (in) 6.2 8.5 9.1 9.8 10.4 11.0 11.6 7.0 7.5 8.1 8.6 9.2 9.8Total volume (ft3) 1,337 1,449 1,556 1,779 2,003 2,236 2,474 1,463 1,573 1,799 2,024 2,266 2,522Merchantable volume (ft3) 1,150 1,253 1,352 1,525 1,720 1,918 2,176 1,252 1,353 1,519 1,707 1,898 2,141Basal area (ft2) 80 80 91 102 114 125 137 80 92 104 116 129 143Stand density index 177 155 173 190 205 221 236 169 189 208 226 245 264Canopy cover (percent) 54 53 58 62 66 70 73 54 59 64 69 73 76Crown competition factor 77 76 86 97 109 120 130 77 89 101 116 129 143Canopy base height (ft) 2 2 2 2 3 4 6 2 2 2 2 4 6Canopy bulk density (kg/m3) 0.07 0.07 0.07 0.08 0.09 0.10 0.12 0.07 0.07 0.09 0.11 0.13 0.15

Prescribed fire Trees per acre 384 200 78 77 76 75 74 300 78 77 76 75 74

Quadratic mean diameter (in) 6.2 8.5 13.3 14.2 15.0 15.8 16.6 7.0 13.2 14.2 15.0 15.8 16.6Total volume (ft3) 1,337 1,225 1,329 1,533 1,738 1,940 2,140 1,225 1,328 1,534 1,738 1,939 2,139Merchantable volume (ft3) 1,150 1,083 1,183 1,363 1,561 1,760 1,956 1,083 1,183 1,362 1,562 1,758 1,955Basal area (ft2) 80 80 75 84 93 102 111 80 74 84 93 102 111Stand density index 177 155 122 134 145 156 166 169 122 134 145 156 166Canopy cover (percent) 54 53 48 51 55 58 60 54 48 51 55 58 60Crown competition factor 77 76 65 72 80 86 92 77 65 72 79 86 91Canopy base height (ft) 2 6 10 10 10 11 12 6 10 10 10 11 12Canopy bulk density (kg/m3) 0.07 0.05 0.05 0.06 0.06 0.07 0.07 0.05 0.05 0.06 0.07 0.07 0.07

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Carson National Forest 1
K

93

Table 8d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 9 97 10 3 0 0 0 0 5 100 0 0 0 0 0 0

10 9 92 10 8 0 0 0 0 5 100 0 0 0 0 0 0

20 9 85 10 15 0 0 0 0 5 100 0 0 0 0 0 0

30 9 76 10 24 0 0 0 0 9 100 0 0 0 0 0 0

40 10 100 0 0 0 0 0 0 9 100 0 0 0 0 0 0

50 10 100 0 0 0 0 0 0 9 98 10 2 0 0 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 75 11 25 0 0 0 0 9 90 10 10

10 5 94 10 6 0 0 0 0 9 94 10 6

20 5 97 10 3 0 0 0 0 9 92 10 8

30 9 99 10 1 0 0 0 0 8 89 10 11

40 9 98 10 2 0 0 0 0 8 87 10 13

50 9 96 10 4 0 0 0 0 8 83 10 17

Pile and burn 1 5 100 0 0 0 0 0 0 9 100 0 0

10 5 100 0 0 0 0 0 0 9 100 0 0

20 5 100 0 0 0 0 0 0 9 100 0 0

30 9 100 0 0 0 0 0 0 8 100 0 0

40 9 100 0 0 0 0 0 0 8 99 10 1

50 9 100 0 0 0 0 0 0 8 94 10 6

Prescribed fire 1 5 100 0 0 0 0 0 0 5 100 0 0

10 5 100 0 0 0 0 0 0 5 100 0 0

20 5 100 0 0 0 0 0 0 5 100 0 0

30 5 100 0 0 0 0 0 0 9 100 0 0

40 5 100 0 0 0 0 0 0 9 100 0

50 9 100 0 0 0 0 0 0 9 97 10 3

Region 3 — Carson National Forest 1
L

94

Region 3 — Carson National Forest 1

Table 8d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 9 96 10 4 9 97 10 3

10 9 92 10 8 9 92 10 8

20 9 87 10 13 9 85 10 15

30 9 80 10 20 9 77 10 23

40 10 100 0 0 10 100 0 0

50 10 100 0 0 10 100 0 0

Pile and burn 1 9 100 0 0 9 100 0 0

10 9 100 0 0 9 100 0 0

20 9 100 0 0 9 100 0 0

30 9 95 10 5 9 92 10 8

40 10 100 0 0 10 100 0 0

50 10 100 0 0 10 100 0 0

Prescribed fire 1 5 100 0 0 5 100 0 0

10 5 100 0 0 5 100 0 0

20 5 100 0 0 5 100 0 0

30 9 100 0 0 9 100 0 0

40 9 100 0 9 100 0

50 9 97 10 3 9 96 10 4

tpa = trees per acre; d.b.h. = diameter at breast height.Table 8f—Prescribed fire weather onditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 8e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 18 87 3 5 13 16 50 100Moderate—75th percentile 10 69 5 7 16 19 125 150
Initial stand conditions

A

95

Site: Elevation = 9,000 ft, slope = 35 percent, aspect = 180°.Species (based on trees per acre): White fir (Abies concolor) = 43 percent, Douglas-fir (Pseudotsuga menziesii) = 42 percent, ponderosa pine (Pinus ponderosa) = 12 percent.

Stand attributes: Stem density = 953 tpa, basal area = 157 ft2/ac, top height 

= 65 ft, stand density index = 365, quadratic mean diameter = 5.5 in, crown competition factor = 174, canopy cover = 82 percent.

Region 3 — Carson National Forest 2
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

96

Region 3 — Carson National Forest 2
C

97

Initial conditions/no-action trajectoryThis stand has 953 trees per acre (tpa) composed of Douglas-fir and white fir understory with a low-density ponderosa pine overstory. Canopy bulk density is 0.24 kg/m3 (0.015 lb/ft3), and canopy base height is 3 ft, so ladder fuels are sufficient to enable passive crown fire, but canopy fuels are not sufficient to enable active crown fire for severe fire weather. Surface fire is predicted for moderate fire weather. Woody fuel loading is 9 tons/ac, and litter and duff loading is 7 tons/ac. Predicted flame lengths are low for severe and moderate fire weather, but potential basal area mortality is 100 percent for severe fire weather. With no action, canopy base height and canopy bulk density increase slightly as trees grow, but surface fuels accumulate causing higher potential flame lengths and increasing crown fire hazard. Passive crown fire is predicted in 10 years for moderate fire weather. Active crown fire remains likely for severe fire weather for the duration of the 50-year projection. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and decreases canopy bulk density sufficiently enough to reduce the predicted fire type to surface fire for moderate and severe fire weather. Surface fuels are also reduced, and flame lengths remain similar to initial conditions. All thinning treatments increase canopy base height and reduce canopy bulk density, but thinning to 200 tpa or less is necessary to decrease crown fire potential. All thinning treatments increase surface fuels, which contribute to higher potential flame lengths. The pile and burn and prescribed fire surface fuel treatments reduce woody surface fuels to below initial levels, and this reduces potential flame lengths and basal area mortality in the more dense treatments. Potential flame lengths and basal area mortality remain high in the more open treatments (50 to 100 tpa), even with surface fuel treatments because fire behavior is driven by grass and brush fuel models. The presence of grass and brush fuels following treatment is site specific, and these results should be interpreted cautiously because grass and brush fuels are not tracked in FFE.

Silvicultural and surface fuel treatments—long-term effectsAll treatments have a long-term effect on crown fire potential, and surface fire remains the predicted fire type for moderate and severe fire weather for the duration of the 50-year projection. Regeneration is low in all treatments, so canopy base height increases over time as trees grow and crowns rise. In stands that had a surface fuel treatment, surface fuels accumulate over time contributing to higher potential flame lengths; all treatments have flame lengths of at least 4 ft for severe fire weather in 50 years. A second treatment may be necessary to reduce surface fuels.

Region 3 — Carson National Forest 2
D

98Table 9a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 10 8 7 5

3–6 in 3 0 4 4 4 36–12 in 3 1 2 3 3 3>12 in 0 0 0 0 0 0Litter 2 1 5 5 4 3Duff 5 4 4 5 5 5

Flame length (ft) Moderate 2 2 4 3 3 3

Severe 3 3 6 5 4 4

Torching index Severe 14 49 45 62 46 25Crowning index Severe 13 26 50 31 24 18Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 30 22 13 16 21 25

Severe 100 23 33 34 33 32

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 2 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 5 4 4 3Duff 4 5 5 5

Flame length (ft) Moderate 4 2 2 2

Severe 6 3 3 3

Torching index Severe 34 88 87 52Crowning index Severe 50 31 24 18Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 12 16 21 25

Severe 35 16 21 25

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 1 1 1 1>12 in 0 0 0 0Litter 0 1 1 1Duff 3 4 4 4

Flame length (ft) Moderate 4 4 2 2

Severe 6 6 5 3

Torching index Severe 33 37 39 85Crowning index Severe 57 40 35 29Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 11 15 18 20

Severe 38 41 43 20

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 3 — Carson National Forest 2
E

99

Table 9b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 4 6 8 8 9 1 5 5 5 5 6

3–6 in 3 3 3 4 4 5 0 3 3 3 3 46–12 in 3 3 3 4 4 5 1 4 4 4 4 4>12 in 0 0 1 1 2 2 0 1 1 2 2 2Litter 2 6 7 8 8 9 1 4 4 5 5 5Duff 5 5 6 6 6 7 4 4 4 4 4 5

Flame length (ft) Moderate 2 3 3 4 4 4 2 3 3 3 3 3

Severe 3 4 4 5 5 6 3 4 4 4 4 4

Torching index Severe 14 0 0 0 0 0 49 33 41 46 45 51Crowning index Severe 13 14 14 13 12 12 26 29 26 24 23 22Type of fire Moderate Surface Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Severe Active Active Active Active Active Active Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 43 46 53 51 49 62 189 12 10 10 10 12

18–29.9 in 1 1 2 2 2 2 1 1 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 10 7 5 5 4 4 8 6 5 5 5 5

3–6 in 4 4 4 4 4 4 4 4 4 4 4 46–12 in 2 2 2 3 3 3 3 3 3 3 3 3>12 in 0 0 1 1 2 2 0 0 1 1 1 2Litter 5 2 2 2 2 2 5 3 3 3 3 4Duff 4 4 4 4 5 5 5 5 5 6 6 6

Flame length (ft) Moderate 4 3 3 2 2 2 3 3 3 3 3 3

Severe 6 5 5 5 5 5 5 4 4 4 4 4

Torching index Severe 45 51 52 58 60 58 62 71 81 85 94 104Crowning index Severe 50 52 49 48 47 46 31 33 32 31 30 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 8 6 6 6 6 6 8 7 7 7 8 8

18–29.9 in 1 1 2 2 3 3 1 1 2 2 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 2
F

100Table 9b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 3 3 3 4 2 2 3 4 4 5

3–6 in 1 1 1 2 2 2 1 1 2 2 2 26–12 in 1 1 1 1 2 2 1 1 1 2 2 2>12 in 0 0 1 1 2 2 0 0 1 1 1 2Litter 5 2 2 2 2 3 4 3 3 3 3 4Duff 4 4 4 4 4 4 5 5 5 5 5 5

Flame length (ft) Moderate 4 2 2 2 2 2 2 2 2 2 2 3

Severe 6 6 5 5 5 5 3 3 3 3 3 3

Torching index Severe 34 48 50 57 59 58 88 109 104 98 101 107Crowning index Severe 50 50 47 46 44 44 31 33 32 31 30 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 8 6 6 6 6 6 8 7 7 8 8 8

18–29.9 in 1 1 2 2 2 3 1 1 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 2 3 3 3 0 2 3 3 4 4

3–6 in 0 1 1 1 2 2 1 1 1 2 2 26–12 in 1 2 2 2 2 3 1 3 4 4 4 4>12 in 0 1 1 2 2 3 0 1 1 2 2 3Litter 0 2 2 2 2 2 4 2 3 3 3 3Duff 3 3 3 3 3 3 5 4 4 4 4 4

Flame length (ft) Moderate 4 2 2 2 2 2 4 2 2 2 3 3

Severe 6 6 6 5 5 5 6 5 5 3 4 4

Torching index Severe 33 48 52 59 62 60 37 54 59 86 86 89Crowning index Severe 57 54 52 50 48 48 40 41 39 37 36 36Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 18 11 8 7 7 7 24 11 8 7 7 7

18–29.9 in 1 1 2 2 3 3 1 1 2 2 2 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 2
G

101

Table 9b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 7 6 5 5 6 6 5 5 5 6 7 7

3–6 in 4 4 4 4 4 4 3 3 3 4 4 46–12 in 3 3 3 3 3 4 3 3 3 3 4 5>12 in 0 0 1 1 1 2 0 0 1 1 1 2Litter 4 4 4 5 5 5 3 5 5 6 6 6Duff 5 5 5 6 6 6 5 5 5 6 6 6

Flame length (ft) Moderate 3 3 3 3 3 3 3 3 3 3 3 4

Severe 4 4 4 4 4 4 4 4 4 4 4 5

Torching index Severe 46 52 58 63 63 75 25 23 22 33 35 33

Crowning index Severe 24 26 25 24 24 23 18 19 18 18 18 18Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Conditional Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 9 8 9 9 10 14 10 10 15 22 23 21

18–29.9 in 1 1 2 2 2 2 1 1 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 3 4 5 6 1 3 4 5 6 7

3–6 in 1 1 2 2 2 2 1 1 1 2 2 36–12 in 1 1 1 2 2 2 1 1 1 2 2 3>12 in 0 0 1 1 1 2 0 0 1 1 1 2Litter 4 4 4 5 5 5 3 5 5 6 6 6Duff 5 5 5 5 5 6 5 5 5 5 5 6

Flame length (ft) Moderate 2 2 2 2 3 3 2 2 2 3 3 3

Severe 3 3 3 3 4 4 3 3 3 4 4 4

Torching index Severe 87 77 70 69 65 69 52 37 29 36 39 49Crowning index Severe 24 26 25 24 24 23 18 19 18 18 19 18Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Conditional Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 9 8 9 9 10 15 10 10 15 22 24 21

18–29.9 in 1 1 2 2 2 2 1 1 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Carson National Forest 2
H

102

Table 9c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 953 896 845 798 753 697 233 230 225 219 213 206

Quadratic mean diameter (in) 5.5 6.1 6.7 7.2 7.8 8.4 5.5 10.2 11.0 11.8 12.6 13.3Total volume (ft 3) 3,149 3,694 4,267 4,856 5,481 6,035 2,708 2,944 3,426 3,908 4,389 4,860Merchantable volume (ft 3) 2,482 2,941 3,422 3,933 4,443 4,966 2,292 2,483 2,935 3,360 3,792 4,236Basal area (ft 2) 157 181 204 228 250 268 120 129 148 166 184 200

Stand density index 365 404 440 474 506 527 222 236 262 286 308 327Canopy closure (percent) 82 86 90 92 94 95 68 71 76 79 83 85Crown competition factor 174 200 227 253 278 299 115 124 143 158 175 188Canopy base height (ft) 3 3 3 4 4 5 7 8 9 10 10 11Canopy bulk density (kg/m3) 0.24 0.21 0.22 0.23 0.25 0.25 0.10 0.09 0.10 0.11 0.12 0.13

Table 9b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 3 4 4 5 0 4 4 4 5 5

3–6 in 0 2 2 2 3 3 0 3 3 3 3 36–12 in 1 4 4 4 4 4 1 4 4 4 4 4>12 in 0 1 1 2 2 3 0 1 1 2 2 3Litter 1 3 3 3 4 4 1 3 4 4 4 4Duff 4 4 4 4 4 4 4 4 4 4 4 4

Flame length (ft) Moderate 2 2 2 3 3 3 2 2 3 3 3 3

Severe 5 3 3 4 4 4 3 3 4 4 4 4

Torching index Severe 39 67 75 81 91 96 85 60 62 70 80 86Crowning index Severe 35 36 34 33 31 30 29 31 30 29 28 27Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 34 11 9 8 8 8 50 12 10 9 9 9

18–29.9 in 1 1 2 2 2 2 1 2 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Carson National Forest 2
I

103

Table 9c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 953 50 63 61 59 57 55 100 105 102 99 97 94

Quadratic mean diameter (in) 5.5 17.1 16.0 16.9 17.8 18.7 19.6 13.9 14.4 15.3 16.2 17.1 17.9Total volume (ft3) 3,149 2,224 2,356 2,600 2,833 3,052 3,257 2,782 2,980 3,363 3,736 4,101 4,448Merchantable volume (ft3) 2,482 1,961 2,086 2,316 2,529 2,727 2,907 2,417 2,586 2,942 3,291 3,627 3,945Basal area (ft2) 157 80 88 95 102 109 116 106 119 131 143 154 164

Stand density index 365 118 134 142 149 156 163 170 189 203 216 228 239Canopy cover (percent) 82 47 50 52 54 56 58 61 64 67 70 72 74

Crown competition factor 174 64 69 74 78 83 87 93 103 112 119 127 135Canopy base height (ft) 3 19 19 19 20 20 19 18 18 19 19 20 21

Canopy bulk density (kg/m3) 0.24 0.04 0.04 0.04 0.05 0.05 0.05 0.08 0.07 0.08 0.08 0.08 0.08

Pile and burn Trees per acre 953 50 71 69 67 64 62 100 109 106 103 100 98

Quadratic mean diameter (in) 5.5 17.1 15.1 15.9 16.8 17.7 18.5 13.9 14.1 15.0 15.9 16.8 17.6Total volume (ft3) 3,149 2,224 2,356 2,600 2,837 3,059 3,268 2,782 2,980 3,363 3,738 4,104 4,454Merchantable volume (ft3) 2,482 1,961 2,086 2,316 2,531 2,730 2,912 2,417 2,586 2,942 3,292 3,629 3,949Basal area (ft2) 157 80 88 95 103 110 116 106 119 131 143 154 164

Stand density index 365 118 137 145 153 161 167 170 190 204 218 230 241

Canopy cover (percent) 82 47 50 52 54 57 59 61 64 67 70 72 74Crown competition factor 174 64 69 74 79 83 88 93 103 112 119 127 135Canopy base height (ft) 3 19 19 19 20 20 19 18 18 19 19 20 21

Canopy bulk density (kg/m3) 0.24 0.04 0.04 0.05 0.05 0.05 0.05 0.08 0.07 0.08 0.08 0.08 0.09

Prescribed fire Trees per acre 953 50 85 83 80 77 74 100 99 97 94 91 88

Quadratic mean diameter (in) 5.5 17.1 13.0 13.7 14.5 15.3 16.1 13.9 13.6 14.5 15.4 16.2 17.1Total volume (ft3) 3,149 2,031 2,153 2,375 2,597 2,803 2,999 2,422 2,594 2,923 3,250 3,557 3,862Merchantable volume (ft3) 2,482 1,810 1,927 2,142 2,342 2,528 2,701 2,127 2,281 2,594 2,899 3,184 3,465Basal area (ft2) 157 80 79 85 92 99 106 106 101 111 121 131 140

Stand density index 365 118 130 138 146 154 161 170 163 176 187 198 208Canopy cover (percent) 82 47 45 48 50 53 55 61 57 60 63 65 67Crown competition factor 174 64 60 64 70 75 80 93 84 91 98 105 111Canopy base height (ft) 3 19 20 21 22 22 21 18 19 19 20 20 21

Canopy bulk density (kg/m3) 0.24 0.04 0.04 0.04 0.04 0.04 0.05 0.06 0.06 0.06 0.06 0.07 0.07

Region 3 — Carson National Forest 2
J

104Table 9c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 953 200 200 195 190 185 176 300 297 286 269 253 241

Quadratic mean diameter (in) 5.5 10.9 11.7 12.6 13.4 14.1 14.9 9.3 10.1 10.9 11.7 12.5 13.2Total volume (ft3) 3,149 3,136 3,388 3,894 4,393 4,882 5,292 3,292 3,572 4,109 4,586 5,048 5,516Merchantable volume (ft3) 2,482 2,696 2,879 3,348 3,769 4,201 4,582 2,765 2,995 3,493 3,908 4,294 4,727Basal area (ft2) 157 130 149 168 185 201 213 143 166 186 202 216 230Stand density index 365 230 257 281 302 322 334 269 303 329 347 363 378Canopy cover (percent) 82 71 75 79 82 84 85 76 81 84 86 88 89Crown competition factor 174 123 140 156 169 184 191 144 166 186 199 212 223Canopy base height (ft) 3 11 11 12 13 13 14 6 6 6 8 9 11Canopy bulk density (kg/m3) 0.24 0.11 0.10 0.11 0.11 0.11 0.12 0.16 0.15 0.16 0.16 0.16 0.16

Pile and burn Trees per acre 953 200 202 197 192 187 178 300 299 289 271 255 243

Quadratic mean diameter (in) 5.5 10.9 11.7 12.5 13.3 14.0 14.8 9.3 10.1 10.9 11.7 12.5 13.2Total volume (ft3) 3,149 3,136 3,388 3,894 4,393 4,879 5,289 3,292 3,572 4,121 4,600 5,059 5,528Merchantable volume (ft3) 2,482 2,696 2,879 3,348 3,769 4,198 4,579 2,765 2,995 3,503 3,926 4,304 4,741Basal area (ft2) 157 130 149 168 185 201 213 143 166 187 202 216 231Stand density index 365 230 258 281 303 322 334 269 303 331 349 364 379Canopy cover (percent) 82 71 75 79 82 84 85 76 81 84 86 88 89Crown competition factor 174 123 140 156 169 184 191 144 166 186 199 212 223Canopy base height (ft) 3 11 11 12 13 13 14 6 6 6 8 9 11Canopy bulk density (kg/m3) 0.24 0.11 0.10 0.11 0.11 0.11 0.12 0.16 0.15 0.16 0.16 0.15 0.16

Prescribed fire Trees per acre 953 200 138 135 131 128 124 300 173 169 164 159 155

Quadratic mean diameter (in) 5.5 10.9 12.5 13.4 14.3 15.1 15.9 9.3 11.4 12.3 13.2 14.0 14.8Total volume (ft3) 3,149 2,609 2,814 3,223 3,627 4,028 4,421 2,667 2,888 3,327 3,763 4,197 4,629Merchantable volume (ft3) 2,482 2,275 2,434 2,822 3,171 3,540 3,908 2,302 2,482 2,898 3,278 3,661 4,062Basal area (ft2) 157 130 117 132 146 159 172 143 124 140 155 170 184

Stand density index 365 230 197 215 232 248 262 269 215 236 255 273 289Canopy cover (percent) 82 71 64 69 72 74 77 76 68 72 75 78 80Crown competition factor 174 123 103 116 126 137 145 144 113 128 139 152 163Canopy base height (ft) 3 14 14 16 17 18 19 13 13 13 14 16 17Canopy bulk density (kg/m3) 0.24 0.07 0.07 0.07 0.08 0.08 0.09 0.09 0.08 0.09 0.09 0.09 0.10

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Carson National Forest 2
K

105

Table 9d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 9 93 10 7 0 0 0 0 9 100 0 0 0 0 0 0

10 10 60 9 40 0 0 0 0 10 58 9 42 0 0 0 0

20 10 95 9 5 0 0 0 0 10 69 9 31 0 0 0 0

30 10 87 12 13 0 0 0 0 10 75 9 25 0 0 0 0

40 10 74 12 26 0 0 0 0 10 83 9 17 0 0 0 0

50 10 62 12 38 0 0 0 0 10 92 9 8 0 0 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 87 12 13 10 96 12 4

10 10 60 5 40 10 66 9 34

20 5 53 10 47 10 59 9 41

30 5 57 10 43 10 59 9 41

40 5 57 10 43 10 64 9 36

50 5 56 10 44 10 70 9 30

Pile and burn 1 2 80 10 20 9 88 10 12

10 5 100 0 0 9 96 10 4

20 5 97 10 3 9 86 10 14

30 5 89 10 11 9 75 10 25

40 5 81 10 19 9 64 10 36

50 5 75 10 25 9 53 10 47

Prescribed fire 1 2 100 0 0 2 100 0 0

10 5 100 0 0 5 99 10 1

20 5 100 0 0 5 83 10 17

30 5 91 10 9 9 72 10 28

40 5 83 10 17 9 62 10 38

50 5 76 10 24 9 54 10 46

Region 3 — Carson National Forest 2
L

106

Region 3 — Carson National Forest 2

Table 9d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 200 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 80 9 20 0 0 0 0 10 51 9 49 0 0 0 0

10 10 66 9 34 0 0 0 0 10 60 9 40 0 0 0 0

20 10 67 9 33 0 0 0 0 10 70 9 30 0 0 0 0

30 10 73 9 27 0 0 0 0 10 86 9 14 0 0 0 0

40 10 83 9 17 0 0 0 0 10 97 12 3 0 0 0 0

50 10 95 9 5 10 86 12 14 0 0 0 0

Pile and burn 1 9 99 10 1 0 0 0 0 9 100 0 0 0 0 0 0

10 9 89 10 11 0 0 0 0 9 84 10 16 0 0 0 0

20 9 73 10 27 0 0 0 0 9 63 10 37 0 0 0 0

30 9 58 10 42 0 0 0 0 10 59 9 41 0 0 0 0

40 10 56 9 44 0 0 0 0 10 81 9 19 0 0 0 0

50 10 72 9 28 0 0 0 0 10 99 12 1 0 0 0 0

Prescribed fire 1 5 100 0 0 0 0 0 0 9 100 0 0 0 0 0 0

10 9 78 10 22 0 0 0 0 9 66 10 34 0 0 0 0

20 9 63 10 37 0 0 0 0 9 51 10 49 0 0 0 0

30 9 53 10 47 0 0 0 0 10 58 9 42 0 0 0 0

40 10 56 9 44 0 0 0 0 10 67 9 33 0 0 0 0

50 10 66 9 34 0 0 0 0 10 77 9 23 0 0 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.Table 9f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 9e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 18 84 3 5 13 16 50 100Moderate—75th percentile 10 75 5 7 16 19 125 150
Initial stand conditions

A

107

Site: Elevation = 7,000 ft, slope = 1 percent, aspect = 270°.Species (based on trees per acre): Ponderosa pine (Pinus ponderosa) = 100 percent.

Stand attributes: Stem density = 496 tpa, basal area = 106 ft2/ac, top height = 41 ft, stand density index = 234, quadratic mean diameter = 6.3 in, crown competition factor = 84, canopy cover = 57 percent.

Region 3 — Kaibab National Forest
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

108

Region 3 — Kaibab National Forest
C

109

Initial conditions/no-action trajectoryThis is a pure ponderosa pine stand with 496 trees per acre (tpa). Canopy bulk density is 0.10 kg/m3 (0.0062 lb/ft3), and canopy base height is 4 ft, so ladder fuels are sufficient to enable passive crown fire, and canopy fuels are sufficient to enable active crown fire for severe fire weather. Woody fuel loading is 7 tons/ac, and litter and duff loading is 7 tons/ac. Despite the relatively low woody fuel loading, potential flame lengths are 6 ft and potential basal area mortality is 100 percent for severe fire weather because the predominant fuel model is 5 (fire behavior is driven by brush fuels). Brush fuels are not entered and tracked in the FFE, so these results should be interpreted with caution. With no action, canopy base height increases as the trees grow and crown fire potential declines; fire type changes from active crown fire to conditional crown fire in 30 years and to surface fire in 50 years. Surface fuels accumulate, but flame lengths decrease over time as the predominant fuel model shifts from model 5 to fuel models 9 and 10. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment effectively reduces surface fuels, but does not affect canopy base height and canopy bulk density enough to decrease crown fire potential. Thinning to 50 tpa is required to increase canopy base height and decrease canopy bulk density, but even with this treatment, potential flame lengths and basal area mortality remain high, and the predicted fire type is passive crown fire for severe fire weather. The 200 and 300 tpa treatments have essentially no effect on forest structure, and basal area mortality remains 100 percent for severe fire weather. All treatments have flame lengths of 1 ft and low basal area mortality for moderate fire weather. The pile and burn and prescribed fire treatments reduce woody surface fuels in all size classes; potential flame lengths and basal area mortality remain high for severe fire weather because the predominant fuel model is 5, suggesting that brush fuels would drive fire behavior in these open stands with low woody fuels. The FFE model does not track brush fuels directly so these results should be interpreted with caution. 

Silvicultural and surface fuel treatments—long-term effectsAlthough the treatments have little effect on crown fire potential in the short term, they do reduce crown fire potential in the long term. In all treatments, canopy base height increases over time as the trees grow and the stand self-thins. Flame lengths remain high for severe fire weather, but the increase in canopy base height causes the predicted fire type to shift to surface fire in 10 years for the prescribed fire only, 50 tpa, 100 tpa, and 200 tpa treatments. The predicted fire type remains surface fire for the 50-year trajectory although fuel model 5 still drives fire behavior, and flame lengths remain at least 4 ft for severe fire weather. Crown fire potential remains high in the 300 tpa treatment for 40 years. The 300 tpa treatment with prescribed fire has a greater long-term effect on crown fire potential because fire-caused mortality of overstory trees increases canopy base height enough that the predicted fire type changes from active to passive crown fire initially and then to surface fire in 30 years. 

Region 3 — Kaibab National Forest
D

110Table 10a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 4 4 3 3

3–6 in 2 0 2 2 2 26–12 in 2 1 2 2 2 2>12 in 0 0 0 0 0 0Litter 2 1 2 2 2 2Duff 5 3 4 4 5 5

Flame length (ft) Moderate 1 1 2 2 1 1

Severe 6 6 6 6 6 6

Torching index Severe 11 12 26 13 14 11Crowning index Severe 29 39 41 35 29 29Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Active Passive Passive Passive Active Active

Potential basal area mortality (%) Moderate 20 16 10 14 19 20

Severe 100 98 96 98 100 100

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 2 2 2 2Duff 3 4 4 4

Flame length (ft) Moderate 1 1 1 1

Severe 7 6 6 6

Torching index Severe 25 12 14 11Crowning index Severe 41 35 29 29Type of fire Moderate Surface Surface Surface Surface

Severe Passive Passive Active Active

Potential basal area mortality (%) Moderate 10 14 19 20

Severe 96 98 100 100

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 1 1 1 1>12 in 0 0 0 0Litter 1 1 1 1Duff 3 3 3 3

Flame length (ft) Moderate 1 1 1 1

Severe 7 6 6 6

Torching index Severe 24 11 12 12Crowning index Severe 45 41 39 39Type of fire Moderate Surface Surface Surface Surface

Severe Passive Passive Passive Passive

Potential basal area mortality (%) Moderate 9 12 15 16

Severe 96 98 98 98

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 3 — Kaibab National Forest
E

111

Table 10b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 4 5 6 6 7 1 4 4 4 5 5

3–6 in 2 3 3 3 4 4 0 1 1 2 2 36–12 in 2 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 1 1 1 1Litter 2 4 5 5 5 5 1 3 3 4 4 4Duff 5 5 5 5 6 6 3 3 4 4 4 4

Flame length (ft) Moderate 1 2 2 2 2 2 1 1 2 2 2 2

Severe 6 4 4 4 4 4 6 6 6 4 4 4

Torching index Severe 11 25 29 41 49 56 12 27 25 46 60 71Crowning index Severe 29 26 27 29 30 31 39 42 38 38 39 40Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Active Active Active Cond. Cond. Surface Passive Passive Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 6 9 13 25 26 22 103 8 6 4 4 4

18–29.9 in 0 0 0 0 0 0 1 1 1 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 4 4 4 4 5 4 4 4 5 5 5

3–6 in 2 2 2 3 3 3 2 2 3 3 3 46–12 in 2 2 2 2 2 2 2 2 2 2 2 2>12 in 0 0 0 0 0 1 0 0 0 0 0 0Litter 2 2 2 2 2 3 2 3 3 3 3 4Duff 4 4 4 4 4 4 4 4 4 5 5 5

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 2

Severe 6 6 6 6 6 6 6 6 5 4 4 4

Torching index Severe 26 43 51 63 66 72 13 38 40 54 64 88

Crowning index Severe 41 57 55 55 54 55 35 41 42 42 42 43Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 2 3 3 3 3 2 3 4 4 4 4

18–29.9 in 0 0 1 1 1 1 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Kaibab National Forest
F

112Table 10b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 3 3 4 4 1 2 3 4 5 5

3–6 in 1 1 1 1 2 2 1 1 1 2 2 26–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 1 0 0 0 0 0 0Litter 2 2 2 2 3 3 2 3 3 3 4 4Duff 3 3 3 3 4 4 4 4 4 4 4 4

Flame length (ft) Moderate 1 1 1 1 2 2 1 1 1 2 2 2

Severe 7 6 6 6 6 6 6 6 6 3 4 4

Torching index Severe 25 42 50 60 63 69 12 37 40 57 68 91Crowning index Severe 41 53 51 52 49 51 35 41 42 40 41 42Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 2 3 3 3 3 2 3 4 4 4 4

18–29.9 in 0 0 1 1 1 1 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 3 3 3 4 0 3 3 4 4 5

3–6 in 0 1 1 1 2 2 1 1 1 1 2 26–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 1 2 2 3 3 3 2 2 3 3 3 3Duff 3 3 3 3 3 3 4 3 3 3 3 4

Flame length (ft) Moderate 1 1 1 1 2 2 1 1 1 2 2 2

Severe 7 7 6 6 6 6 6 6 6 6 5 5

Torching index Severe 24 40 45 48 50 51 11 37 43 35 48 60Crowning index Severe 45 47 46 46 43 43 41 45 45 43 43 44Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 9 8 5 3 3 3 15 8 5 3 3 3

18–29.9 in 1 1 1 1 1 1 1 1 1 1 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Kaibab National Forest
G

113

Table 10b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 4 5 5 6 7 3 4 5 5 6 7

3–6 in 2 3 3 3 4 4 2 3 3 3 4 46–12 in 2 2 2 2 2 2 2 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 4 4 4 4 4 2 4 4 5 5 5Duff 5 5 5 5 5 6 5 5 5 5 6 6

Flame length (ft) Moderate 1 2 2 2 2 2 1 2 2 2 2 2

Severe 6 4 4 4 4 4 6 4 4 4 4 4

Torching index Severe 14 39 38 49 68 70 11 30 29 46 54 61Crowning index Severe 29 34 32 33 34 35 29 28 29 29 30 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Surface Surface Active Active Active Cond. Cond. Surface

Hard snags (stems/ac) 0–17.9 in 3 4 5 5 5 4 4 6 7 4 13 17

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 4 5 6 6 1 2 4 5 6 7

3–6 in 1 1 1 2 2 3 1 1 1 2 2 36–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 4 4 4 4 4 2 4 4 5 5 5Duff 4 4 4 5 5 5 4 4 5 5 5 5

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 2 2 2 2

Severe 6 3 3 3 4 4 6 3 3 3 4 4

Torching index Severe 14 58 45 53 65 79 11 44 34 49 55 63Crowning index Severe 29 34 32 33 34 35 29 28 29 29 30 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Surface Surface Active Cond. Cond. Cond. Cond. Surface

Hard snags (stems/ac) 0–17.9 in 3 4 5 5 5 4 4 6 7 5 14 17

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Kaibab National Forest
H

114

Table 10c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 496 486 475 450 429 412 139 137 135 132 129 127

Quadratic mean diameter (in) 6.3 6.9 7.5 8.1 8.6 9.1 6.3 11.4 12.3 13.2 13.9 14.6Total volume (ft 3) 1,410 1,879 2,354 2,817 3,275 3,720 1,380 1,572 1,966 2,372 2,771 3,156Merchantable volume (ft 3) 1,176 1,596 2,038 2,461 2,836 3,277 1,204 1,390 1,777 2,124 2,521 2,913Basal area (ft 2) 106 127 145 160 174 186 91 98 112 125 137 148Stand density index 234 269 298 319 338 355 160 170 189 205 220 233Canopy closure (percent) 57 63 68 71 74 77 57 50 54 58 62 65Crown competition factor 84 101 114 125 135 145 68 74 83 92 101 108Canopy base height (ft) 4 5 6 8 9 10 5 9 8 10 13 15Canopy bulk density (kg/m3) 0.10 0.11 0.11 0.10 0.10 0.09 0.07 0.06 0.07 0.07 0.07 0.06

Table 10b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 3 4 5 5 0 3 4 4 5 5

3–6 in 0 1 1 2 2 3 0 1 1 2 2 36–12 in 1 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 1 3 3 4 4 4 1 3 3 4 4 4Duff 3 3 3 4 4 4 3 3 4 4 4 4

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 2 2 2 2

Severe 6 6 6 5 4 4 6 6 6 4 4 4

Torching index Severe 12 30 28 38 64 75 12 26 25 46 60 67Crowning index Severe 39 42 39 40 41 41 39 41 37 38 39 39Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Surface Surface Surface Passive Passive Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 30 8 6 4 4 4 52 8 6 4 4 4

18–29.9 in 1 1 1 1 0 0 1 1 1 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; Cond. = conditional.

Region 3 — Kaibab National Forest
I

115

Table 10c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 496 496 50 64 63 62 61 100 106 104 102 100 98

Quadratic mean diameter (in) 6.3 6.3 16.7 15.7 16.7 17.5 18.4 12.9 13.4 14.3 15.1 15.9 16.6Total volume (ft3) 1,410 1,410 1,356 1,520 1,842 2,163 2,477 1,492 1,686 2,073 2,465 2,849 3,215Merchantable volume (ft3) 1,176 1,176 1,209 1,375 1,700 2,024 2,347 1,311 1,504 1,887 2,224 2,611 2,987Basal area (ft2) 106 106 76 86 95 103 111 90 104 116 127 138 147Stand density index 234 234 114 132 143 152 161 150 169 184 198 210 221Canopy cover (percent) 57 57 42 46 49 51 53 49 54 57 60 63 65

Crown competition factor 84 84 55 61 67 72 76 68 77 85 92 100 106Canopy base height (ft) 4 4 10 15 17 20 20 5 12 12 12 14 19Canopy bulk density (kg/m3) 0.10 0.10 0.06 0.04 0.04 0.04 0.04 0.08 0.06 0.06 0.06 0.06 0.06

Pile and burn Trees per acre 496 50 72 71 70 68 67 100 110 108 106 104 102

Quadratic mean diameter (in) 6.3 16.7 14.8 15.7 16.5 17.3 18.0 12.9 13.1 14.0 14.8 15.6 16.3Total volume (ft3) 1,410 1,356 1,520 1,842 2,165 2,482 2,783 1,492 1,686 2,073 2,466 2,852 3,219Merchantable volume (ft3) 1,176 1,209 1,375 1,700 2,023 2,348 2,662 1,311 1,504 1,887 2,224 2,611 2,989Basal area (ft2) 106 76 86 95 104 112 119 90 104 116 127 138 147Stand density index 234 114 135 146 156 165 173 150 171 186 200 212 223Canopy cover (percent) 57 42 46 49 51 54 56 49 54 57 60 63 65

Crown competition factor 84 55 61 67 72 77 82 68 77 85 92 100 106Canopy base height (ft) 4 10 15 17 19 19 20 5 12 12 11 14 19Canopy bulk density (kg/m3) 0.10 0.06 0.04 0.05 0.04 0.05 0.05 0.08 0.06 0.06 0.06 0.06 0.06

Prescribed fire Trees per acre 496 50 88 86 85 84 82 100 97 95 93 92 90

Quadratic mean diameter (in) 6.3 16.7 12.8 13.6 14.3 15.1 15.8 12.9 13.0 13.9 14.7 15.5 16.2Total volume (ft3) 1,410 1,239 1,392 1,697 2,008 2,312 2,606 1,322 1,495 1,841 2,199 2,546 2,875Merchantable volume (ft3) 1,176 1,109 1,264 1,570 1,878 2,187 2,488 1,169 1,344 1,678 2,010 2,362 2,702Basal area (ft2) 106 76 78 87 95 104 112 90 89 99 110 120 129Stand density index 234 114 130 141 152 162 171 150 147 160 173 185 195Canopy cover (percent) 57 42 42 45 49 51 54 49 48 51 55 57 60

Crown competition factor 84 55 55 61 66 72 77 68 65 72 79 86 91Canopy base height (ft) 4 10 15 16 16 16 18 5 13 14 11 14 19Canopy bulk density (kg/m3) 0.10 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.05 0.05 0.06 0.06 0.06

Region 3 — Kaibab National Forest
J

116Table 10c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 496 200 200 196 192 189 186 300 298 293 289 276 263

Quadratic mean diameter (in) 6.3 9.7 10.5 11.3 12.0 12.7 13.2 8.0 8.7 9.4 10.0 10.7 11.3Total volume (ft3) 1,410 1,608 1,831 2,290 2,752 3,212 3,662 1,629 1,857 2,332 2,828 3,281 3,705Merchantable volume (ft3) 1,176 1,381 1,594 2,030 2,459 2,853 3,307 1,381 1,595 2,043 2,480 2,877 3,304

Basal area (ft2) 106 104 121 137 152 165 178 106 125 142 159 172 183Stand density index 234 192 217 239 259 276 292 211 241 267 291 307 320Canopy cover (percent) 57 55 61 65 68 71 74 57 62 67 71 73 75Crown competition factor 84 81 93 105 115 125 135 83 98 110 123 132 140Canopy base height (ft) 4 5 8 8 10 13 14 4 6 6 9 10 11Canopy bulk density (kg/m3) 0.10 0.10 0.08 0.09 0.08 0.08 0.08 0.10 0.10 0.10 0.10 0.10 0.09

Pile and burn Trees per acre 496 200 202 198 194 191 188 300 300 295 291 278 265

Quadratic mean diameter (in) 6.3 9.7 10.5 11.3 12.0 12.6 13.2 8.0 8.7 9.4 10.0 10.7 11.2Total volume (ft3) 1,410 1,608 1,831 2,290 2,753 3,209 3,658 1,629 1,857 2,332 2,828 3,279 3,699

Merchantable volume (ft3) 1,176 1,381 1,594 2,030 2,453 2,850 3,302 1,381 1,595 2,043 2,480 2,874 3,299

Basal area (ft2) 106 104 121 137 152 165 178 106 125 142 159 172 183Stand density index 234 192 218 240 259 276 292 211 241 267 292 307 320Canopy cover (percent) 57 55 61 65 68 71 74 57 62 67 71 73 75Crown competition factor 84 81 93 105 115 125 134 83 98 110 123 132 140Canopy base height (ft) 4 5 8 8 10 12 14 4 6 6 9 10 11Canopy bulk density (kg/m3) 0.10 0.10 0.08 0.09 0.08 0.08 0.08 0.10 0.10 0.10 0.10 0.10 0.09

Prescribed fire Trees per acre 496 200 125 123 121 119 116 300 145 143 140 137 135

Quadratic mean diameter (in) 6.3 9.7 11.9 12.8 13.6 14.4 15.1 8.0 11.1 12.0 12.8 13.5 14.2Total volume (ft3) 1,410 1,376 1,565 1,953 2,348 2,739 3,118 1,380 1,572 1,966 2,372 2,770 3,158

Merchantable volume (ft3) 1,176 1,204 1,391 1,766 2,105 2,500 2,888 1,204 1,391 1,773 2,118 2,517 2,912Basal area (ft2) 106 104 97 110 123 134 145 106 98 112 125 137 148

Stand density index 234 192 166 183 199 213 226 211 172 191 208 223 236

Canopy cover (percent) 57 55 52 56 59 63 65 57 52 56 60 64 66Crown competition factor 84 81 73 82 90 99 105 83 74 83 92 101 109Canopy base height (ft) 4 5 10 9 11 14 16 5 9 8 10 13 14Canopy bulk density (kg/m3) 0.10 0.07 0.06 0.07 0.06 0.06 0.06 0.07 0.06 0.07 0.07 0.07 0.07

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Kaibab National Forest
K

117

Table 10d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 96 10 4 0 0 0 0 5 100 0 0

10 9 65 10 35 0 0 0 0 5 87 10 13

20 10 53 9 47 0 0 0 0 5 74 10 26

30 10 67 9 33 0 0 0 0 9 65 10 35

40 10 79 9 21 0 0 0 0 9 55 10 45

50 10 89 9 11 0 0 0 0 10 52 9 48

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 75 10 25 5 84 10 16

10 5 82 10 18 5 77 10 23

20 5 80 10 20 5 70 10 30

30 5 79 10 21 9 63 10 37

40 5 74 10 26 9 54 10 46

50 5 67 10 33 10 54 9 46

Pile and burn 1 5 100 0 0 5 100 0 0

10 5 100 0 0 5 100 0 0

20 5 100 0 0 5 91 10 9

30 5 94 10 6 9 80 10 20

40 5 84 10 16 9 66 10 34

50 5 76 10 24 9 57 10 43

Prescribed fire 1 5 100 0 0 5 100 0 0

10 5 100 0 0 5 100 0 0

20 5 98 10 2 5 90 10 10

30 5 90 10 10 5 81 10 19

40 5 81 10 19 5 70 10 30

50 5 72 10 28 5 62 10 38

Region 3 — Kaibab National Forest
L

118

Region 3 — Kaibab National Forest

Table 10d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 93 10 7 0 0 0 0 5 95 10 5 0 0 0

10 9 70 10 30 0 0 0 0 9 69 10 31 0 0 0

30 10 55 9 45 0 0 0 0 10 62 9 38 0 0 0

40 10 65 9 35 0 0 0 0 10 72 9 28 0 0 0

50 10 74 9 26 0 0 0 0 10 83 9 17 0 0 0

Pile and burn 1 5 100 0 0 0 0 0 0 5 100 0 0 0 0 0

10 9 98 10 2 0 0 0 0 9 96 10 4 0 0 0

20 9 77 10 23 0 0 0 0 9 72 10 28 0 0 0

30 9 62 10 38 0 0 0 0 9 56 10 44 0 0 0

40 10 50 9 50 0 0 0 0 10 57 9 43 0 0 0

50 10 60 9 40 0 0 0 0 10 70 9 30 0 0 0

Prescribed fire 1 5 100 0 0 0 0 0 0 5 100 0 0 0 0 0

10 5 94 10 6 0 0 0 0 5 91 10 9 0 0 0

20 5 80 10 20 0 0 0 0 5 77 10 23 0 0 0

30 5 69 10 31 0 0 0 0 9 66 10 34 0 0 0

40 9 59 10 41 0 0 0 0 9 56 10 44 0 0 0

50 9 50 10 50 0 0 0 0 10 52 9 48 0 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.Table 10f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 10e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 30 74 4 6 12 15 50 100Moderate—75th percentile 12 57 8 10 19 26 125 150
Initial stand conditions

A

119

Site: Elevation = 7,100 ft, slope = 35 percent, aspect = 10°.Species (based on trees per acre): Pinyon pine (Pinus edulis) = 86 percent, hardwoods = 12 percent, ponderosa pine (Pinus ponderosa) = 2 percent.

Stand attributes: Stem density = 733 tpa, basal area = 162 ft2/ac, top height 

= 23 ft, stand density index = 356, quadratic mean diameter = 6.4 in, crown competition factor = 190, canopy cover = 85 percent.

Region 3 — Pinyon Woodland
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

120

Region 3 — Pinyon Woodland
C

121

Initial conditions/no-action trajectoryThis has 733 trees per acre (tpa) composed of pinyon pine, hardwoods, and a small component of ponderosa pine. Canopy bulk density is 0.07 kg/m3 (0.0044 lb/ft3), and canopy base height is 4 ft, so ladder fuels are sufficient to enable passive crown fire, but canopy fuels are not sufficient to enable active crown fire spread. Woody fuel loading is 7 tons/ac, litter loading is 8 tons/ac, and duff is negligible in this stand. Potential flame lengths are 5 ft, and potential basal area mortality is 99 percent for severe fire weather and 93 percent for moderate fire weather. With no action, canopy base height and canopy bulk density change little over time, and passive crown fire remains likely under severe fire weather for the 50-year projection. Surface fuels accumulate slowly causing slight increases in potential flame lengths, but flame lengths generally remain around 3 ft for moderate fire weather and 5 ft for severe fire weather. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment greatly increases canopy base height and decreases canopy bulk density because fire-caused tree mortality is high. Only 26 trees per acre remain after treatment. Surface fuels are consumed in the prescribed fire treatment, but then greatly increase in 10 years, likely the result of fallen snags. All thinning treatments increase canopy base height and decrease canopy bulk density; the greater the thinning, the greater is the change in forest structure. All treatments eliminate the potential for passive crown fire for moderate and severe fire weather. However, all thinning treatments increase surface fuel loading, so potential flame lengths and basal area mortality remain high. The pile and burn treatment reduces woody surface fuels, and this decreases potential flame lengths and basal area mortality in the higher density stands (100 tpa, 200 tpa, and 300 tpa). Potential flame lengths and basal area mortality remain high in the 50 tpa treatment following the pile and burn, because the more open stand with low woody surface fuels is characterized by fuel model 5. Brush fuels are not tracked in FFE directly and may or may not be an important contributor to fire behavior depending on the location. The prescribed fire treatment reduces woody surface fuels more than the pile and burn treatment, but all stands are characterized as fuel model 2 following the prescribed burn, so potential flame lengths and basal area mortality remain high. Grass fuels are not tracked in FFE and may or may not be important following prescribed fire depending on the location. 

Silvicultural and surface fuel treatments—long-term effectsRegeneration is low in all treatments, so canopy base height continues to increase over time as the trees grow and the stand self-thins. Crown fire remains unlikely for the duration of the 50-year projection in all treatments. However, flame lengths remain high, especially in stands treated with a prescribed fire, so another treatment may be necessary to reduce grass and brush fuels that accumulate following surface fuel treatments. 

Region 3 — Pinyon Woodland
D

122Table 11a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 8 5 4 4

3–6 in 1 0 12 5 5 26–12 in 3 1 13 6 6 3>12 in 0 0 0 0 0 0Litter 8 0 1 3 2 8Duff 0 0 22 17 17 0

Flame length (ft) Moderate 3 4 3 3 2 3

Severe 5 7 6 4 3 4

Torching index Severe 0 31 26 61 66 23Crowning index Severe 34 169 146 89 57 50Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 93 88 66 44 47 72

Severe 99 98 98 97 95 99

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 1 1 1

3–6 in 1 1 1 16–12 in 1 2 2 1>12 in 0 0 0 0Litter 2 2 2 8Duff 12 15 15 0

Flame length (ft) Moderate 2 1 1 2

Severe 6 1 1 3

Torching index Severe 22 323 296 82Crowning index Severe 146 89 57 50Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 32 37 43 49

Severe 98 37 43 81

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 2 3 3 1>12 in 0 0 0 0Litter 0 1 1 0Duff 9 12 12 0

Flame length (ft) Moderate 3 3 2 3

Severe 6 4 3 4

Torching index Severe 26 61 66 23Crowning index Severe 146 89 57 50Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 66 44 47 72

Severe 98 97 95 99

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 3 — Pinyon Woodland
E

123

Table 11b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 3 5 6 7 7 1 5 3 3 2 2

3–6 in 1 2 2 4 5 5 0 5 5 5 5 46–12 in 3 3 3 4 5 6 1 8 8 7 7 6>12 in 0 0 0 0 1 1 0 2 2 2 2 2Litter 8 6 6 6 6 6 0 1 1 2 2 2Duff 0 0 1 1 1 2 0 0 0 0 0 1

Flame length (ft) Moderate 3 4 3 3 3 4 4 4 4 4 4 4

Severe 5 5 5 5 5 5 7 7 7 7 7 7

Torching index Severe 0 0 0 6 4 0 31 24 27 27 28 29Crowning index Severe 34 35 37 37 40 42 169 152 143 139 139 137Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 26 62 98 82 64 50 196 11 4 1 1 1

18–29.9 in 0 0 0 0 0 0 2 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 8 3 1 1 1 1 5 4 4 4 4 5

3–6 in 12 10 9 8 7 6 5 5 5 5 5 56–12 in 13 12 10 9 8 7 6 6 5 5 5 5>12 in 0 0 0 1 1 1 0 0 0 0 0 1Litter 1 0 0 1 1 1 3 4 4 4 5 5Duff 22 21 21 21 20 20 17 17 17 17 17 17

Flame length (ft) Moderate 3 3 3 4 4 4 3 2 2 3 3 3

Severe 6 6 6 6 6 6 4 4 4 4 4 4

Torching index Severe 26 28 30 34 35 39 61 80 77 79 72 65Crowning index Severe 146 146 143 143 141 139 89 86 85 86 87 87Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 2 3 3 3 3 1 2 4 4 5 5

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Pinyon Woodland
F

124Table 11b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 1 2 2 2 3 1 1 2 3 4 4

3–6 in 1 1 1 2 2 2 1 1 2 2 2 36–12 in 1 1 1 1 1 1 2 2 2 2 2 2>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 2 3 3 3 3 3 2 4 4 4 5 5Duff 12 12 12 12 12 12 15 15 15 15 15 16

Flame length (ft) Moderate 2 3 4 4 4 4 1 1 1 2 2 2

Severe 6 6 6 6 6 6 1 1 2 3 3 3

Torching index Severe 22 25 26 30 32 38 323 384 226 174 135 111Crowning index Severe 146 146 143 143 140 136 89 86 85 86 87 87Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 2 3 3 3 3 1 2 4 4 5 5

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 1 1 1 2 0 2 2 2 3 3

3–6 in 0 1 1 2 2 2 1 2 2 2 2 26–12 in 2 4 4 4 4 3 3 5 5 5 5 5>12 in 0 2 2 2 2 2 0 1 1 1 1 1Litter 0 1 2 2 2 2 2 2 3 3 3 3Duff 9 9 9 9 9 9 15 12 12 12 12 12

Flame length (ft) Moderate 5 4 4 4 4 4 4 4 4 3 3 4

Severe 8 8 8 8 8 7 7 6 6 5 4 6

Torching index Severe 16 14 12 16 21 21 28 28 45 76 115 139Crowning index Severe 346 325 341 308 194 170 134 131 130 129 128 128Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 22 11 5 2 2 2 22 8 5 3 3 3

18–29.9 in 1 0 0 0 0 0 1 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Pinyon Woodland
G

125

Table 11b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 4 4 5 6 6 4 4 5 5 6 7

3–6 in 5 5 5 5 5 6 2 2 3 3 4 46–12 in 6 6 5 6 6 6 3 3 3 3 4 4>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 2 4 5 5 6 6 8 5 5 6 6 7Duff 17 17 17 17 17 17 0 0 1 1 1 2

Flame length (ft) Moderate 2 2 3 3 3 4 3 2 3 3 3 3

Severe 3 4 4 4 5 5 4 3 4 4 4 5

Torching index Severe 66 63 56 41 36 30 23 76 22 22 29 24Crowning index Severe 57 57 62 64 65 65 50 51 52 52 52 52Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 3 4 10 13 12 11 6 15 18 16 13 16

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 3 4 5 6 1 2 3 5 6 7

3–6 in 1 1 2 2 3 4 1 1 1 2 3 36–12 in 2 2 2 2 3 3 1 1 1 2 2 3>12 in 0 0 0 0 0 1 0 0 0 0 0 1Litter 2 4 5 5 6 6 8 5 5 6 6 7Duff 15 15 15 15 16 16 0 0 1 1 1 2

Flame length (ft) Moderate 1 1 2 2 3 3 2 1 3 3 3 3

Severe 1 2 3 3 4 4 3 2 4 4 4 4

Torching index Severe 296 253 141 85 41 41 82 194 22 22 29 29

Crowning index Severe 57 57 62 64 65 66 50 51 52 52 52 52Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 3 4 11 13 12 11 6 15 18 16 13 16

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Pinyon Woodland
H

126

Table 11c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 733 662 562 492 441 401 26 25 25 24 23 23

Quadratic mean diameter (in) 6.4 7.1 7.9 8.5 9.1 9.7 6.4 15.2 16.2 17.0 17.8 18.5Total volume (ft 3) 1,648 2,223 2,648 3,054 3,435 3,804 432 497 623 747 873 994Merchantable volume (ft 3) 1,565 2,072 2,468 2,912 3,327 3,762 421 486 610 733 857 977Basal area (ft 2) 162 182 189 195 200 205 30 32 35 38 40 42Stand density index 356 382 381 382 381 380 47 49 53 56 58 61Canopy closure (percent) 85 87 88 88 88 89 24 26 27 29 30 31Crown competition factor 190 209 212 215 217 218 28 30 32 34 35 37Canopy base height (ft) 4 4 4 5 5 5 17 17 19 20 21 22Canopy bulk density (kg/m3) 0.07 0.06 0.06 0.06 0.05 0.05 0.01 0.01 0.01 0.01 0.01 0.01

Table 11b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 3 3 3 3 0 3 3 3 3 3

3–6 in 0 3 3 3 3 3 0 4 4 4 4 46–12 in 3 6 6 6 6 6 1 7 7 6 6 6>12 in 0 1 1 1 1 1 0 1 1 2 1 2Litter 1 3 3 3 4 4 0 2 2 3 3 3Duff 12 12 12 12 12 12 0 0 0 0 1 1

Flame length (ft) Moderate 1 2 2 2 3 3 4 4 4 3 3 3

Severe 1 6 3 3 5 5 7 6 6 5 6 5

Torching index Severe 239 24 106 97 44 46 27 27 31 60 52 69Crowning index Severe 94 97 97 103 103 104 131 123 122 122 122 118Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 37 9 5 3 3 4 69 9 4 2 2 3

18–29.9 in 1 0 0 0 0 0 1 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Pinyon Woodland
I

127

Table 11c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 733 50 63 62 60 58 57 100 105 103 100 97 95

Quadratic mean diameter (in) 6.4 15.1 14.1 14.9 15.5 16.1 16.6 12.9 13.3 14.2 15.0 15.8 16.5Total volume (ft3) 1,648 946 1,068 1,305 1,528 1,741 1,948 1,384 1,584 1,973 2,360 2,750 3,149Merchantable volume (ft3) 1,565 946 1,068 1,304 1,527 1,739 1,944 1,370 1,570 1,958 2,345 2,735 3,133Basal area (ft2) 162 62 69 74 79 82 85 90 102 113 123 132 141Stand density index 356 97 110 117 122 125 128 150 167 181 193 203 212Canopy cover (percent) 85 45 48 50 52 53 54 60 64 67 69 71 73Crown competition factor 190 60 66 70 74 76 79 91 101 110 118 125 131Canopy base height (ft) 4 12 13 13 14 14 15 10 11 11 12 12 12Canopy bulk density (kg/m3) 0.07 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02

Pile and burn Trees per acre 733 50 71 70 68 66 64 100 109 107 104 101 98

Quadratic mean diameter (in) 6.4 15.1 13.3 14.0 14.6 15.2 15.7 12.9 13.1 14.0 14.8 15.5 16.2Total volume (ft3) 1,648 946 1,067 1,305 1,530 1,746 1,957 1,384 1,584 1,972 2,361 2,753 3,155Merchantable volume (ft3) 1,565 946 1,067 1,304 1,528 1,742 1,950 1,370 1,570 1,958 2,345 2,738 3,139Basal area (ft2) 162 62 69 74 79 83 86 90 102 113 123 132 141Stand density index 356 97 113 119 125 129 132 150 169 182 194 204 214Canopy cover (percent) 85 45 48 50 52 54 55 60 64 67 69 71 73Crown competition factor 190 60 65 70 74 77 79 91 101 110 118 125 131Canopy base height (ft) 4 12 13 13 14 14 15 10 11 11 12 12 12Canopy bulk density (kg/m3) 0.07 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.02

Prescribed fire Trees per acre 733 50 63 61 60 58 57 100 76 74 72 70 68

Quadratic mean diameter (in) 6.4 15.1 9.8 10.2 10.5 11.0 11.6 12.9 12.2 13.0 13.7 14.4 15.1Total volume (ft3) 1,648 459 515 622 728 839 959 829 957 1,207 1,454 1,703 1,957Merchantable volume (ft3) 1,565 459 515 621 721 820 949 819 946 1,195 1,440 1,686 1,936Basal area (ft2) 162 62 33 34 36 38 42 90 61 68 74 79 85Stand density index 356 97 61 63 65 68 72 150 104 112 119 126 132Canopy cover (percent) 85 45 26 27 28 29 31 60 44 47 49 52 54Crown competition factor 190 60 30 31 33 35 38 91 58 63 68 73 77Canopy base height (ft) 4 14 16 16 13 16 16 17 17 19 21 22 24Canopy bulk density (kg/m3) 0.07 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Region 3 — Pinyon Woodland
J

128Table 11c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 733 200 199 188 178 169 162 300 287 270 256 245 233

Quadratic mean diameter (in) 6.4 10.6 11.3 12.2 13.0 13.7 14.4 9.2 10.0 10.8 11.5 12.1 12.7Total volume (ft3) 1,648 1,752 2,025 2,527 3,003 3,470 3,938 1,871 2,136 2,670 3,208 3,748 4,247Merchantable volume (ft3) 1,565 1,736 2,009 2,510 2,986 3,447 3,915 1,849 2,113 2,651 3,191 3,727 4,224Basal area (ft2) 162 122 140 153 164 174 184 138 155 170 184 196 206Stand density index 356 219 244 259 271 282 292 261 285 303 319 334 344Canopy cover (percent) 85 73 77 79 81 82 83 78 81 83 85 87 88Crown competition factor 190 130 146 157 165 172 179 151 167 180 191 201 208Canopy base height (ft) 4 7 8 9 9 10 10 6 7 7 7 8 8Canopy bulk density (kg/m3) 0.07 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04 0.04 0.04

Pile and burn Trees per acre 733 200 201 190 179 171 163 300 289 271 258 247 234

Quadratic mean diameter (in) 6.4 10.6 11.3 12.1 12.9 13.7 14.4 9.2 9.9 10.7 11.4 12.1 12.7Total volume (ft3) 1,648 1,752 2,025 2,526 3,003 3,473 3,944 1,871 2,135 2,670 3,208 3,748 4,244Merchantable volume (ft3) 1,565 1,736 2,009 2,509 2,986 3,449 3,920 1,849 2,112 2,650 3,191 3,727 4,221

Basal area (ft2) 162 122 140 153 164 174 184 138 155 170 184 196 206

Stand density index 356 219 244 259 271 282 292 261 286 303 320 334 344Canopy cover (percent) 85 73 77 79 81 82 83 78 81 83 85 87 88Crown competition factor 190 130 146 156 165 172 179 151 167 180 191 201 208Canopy base height (ft) 4 7 8 9 9 10 10 6 7 7 7 8 8Canopy bulk density (kg/m3) 0.07 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04 0.04 0.04

Prescribed fire Trees per acre 733 200 94 92 90 87 85 300 60 58 57 55 54

Quadratic mean diameter (in) 6.4 10.6 12.1 13.0 13.8 14.6 15.3 9.2 12.9 13.7 14.5 15.2 15.8Total volume (ft3) 1,648 983 1,140 1,454 1,772 2,093 2,422 730 842 1,061 1,280 1,498 1,714Merchantable volume (ft3) 1,565 972 1,128 1,440 1,753 2,073 2,400 719 830 1,047 1,264 1,479 1,691Basal area (ft2) 162 122 75 85 93 101 109 138 54 60 65 69 74Stand density index 356 219 128 140 150 160 168 261 90 97 103 108 113Canopy cover (percent) 85 73 53 56 59 62 64 78 40 43 45 47 49Crown competition factor 190 130 75 83 89 96 102 151 52 56 60 64 67Canopy base height (ft) 4 9 11 12 12 13 13 17 16 18 21 22 23Canopy bulk density (kg/m3) 0.07 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Pinyon Woodland
K

129

Table 11d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 75 6 25 10 100 0 0

10 6 56 10 44 10 67 2 33

20 10 66 6 34 10 58 2 42

30 10 91 6 9 2 54 10 46

40 10 92 12 8 2 63 10 37

50 10 81 12 19 2 68 10 32

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 72 5 27 6 1 0 0 10 58 8 42 0 0 0 0

10 10 49 5 36 6 16 0 0 10 53 8 47 0 0 0 0

20 10 42 6 31 5 27 0 0 10 59 8 41 0 0 0 0

30 6 43 10 39 5 18 0 0 10 66 8 34 0 0 0 0

40 6 52 10 38 5 10 0 0 10 75 8 25 0 0 0 0

50 6 59 10 38 5 3 0 0 10 84 8 16 0 0 0 0

Pile and burn 1 5 97 6 3 0 0 0 0 8 100 0 0 0 0 0 0

10 5 69 6 31 0 0 0 0 8 100 0 0 0 0 0 0

20 6 54 5 46 0 0 0 0 8 86 10 14 0 0 0 0

30 6 69 5 28 10 3 0 0 8 72 10 28 0 0 0 0

40 6 78 5 13 10 8 0 0 8 59 10 41 0 0 0 0

50 6 86 10 13 5 2 0 0 10 53 8 47 0 0 0 0

Prescribed fire 1 2 100 0 0 0 0 0 0 2 100 0 0 0 0 0 0

10 2 93 5 7 0 0 0 0 2 91 10 9 0 0 0 0

20 2 84 5 16 0 0 0 0 2 65 10 19 8 16 0 0

30 2 100 0 0 0 0 0 0 2 42 8 33 10 25 0 0

40 2 100 0 0 0 0 0 0 8 46 10 30 2 24 0 0

50 2 100 0 0 0 0 0 0 2 65 10 35 0 0 0 0

Region 3 — Pinyon Woodland
L

130

Region 3 — Pinyon Woodland

Table 11d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 8 53 10 47 0 0 10 84 8 16 0 0

10 10 59 8 41 0 0 8 57 10 43 0 0

20 10 74 8 26 0 0 10 100 0 0 0 0

30 10 91 8 9 0 0 10 100 0 0 0 0

40 10 95 12 5 0 0 10 100 0 0 0 0

50 10 85 12 15 0 0 10 92 12 8 0 0

Pile and burn 1 8 100 0 0 0 0 8 67 10 33 0 0

10 8 92 10 8 0 0 8 89 10 11 0 0

20 8 70 10 30 0 0 10 100 0 0 0 0

30 10 52 8 48 0 0 10 100 0 0 0 0

40 10 100 0 0 0 0 10 100 0 0 0 0

50 10 100 0 0 0 0 10 100 0 0 0 0

Prescribed fire 1 8 100 0 0 0 0 2 100 0 0 0 0

10 5 72 10 28 0 0 2 57 10 43 0 0

20 8 62 10 38 0 0 2 56 10 44 0 0

30 8 56 10 44 0 0 10 100 0 0 0 0

40 10 100 0 0 0 0 2 46 10 42 8 12

50 10 100 0 0 0 0 10 43 2 36 8 21

tpa = trees per acre, d.b.h. = diameter at breast height.

Table 10f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 11e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 19 85 3 5 13 16 50 100Moderate—75th percentile 10 75 5 7 16 19 125 150
Initial stand conditions

A

131

Site: Elevation = 5,400 ft, slope = 15 percent, aspect = 360°.Species (based on trees per acre): Ponderosa pine (Pinus ponderosa) = 77 percent, gambel oak (Quercus gambelii) = 21 percent, Douglas-fir (Pseudotsuga menziesii) = 2 percent.

Stand attributes: Stem density = 571 tpa, basal area = 79 ft2/ac, top height 

= 45 ft, stand density index = 190, quadratic mean diameter = 5.0 in, crown competition factor = 67, canopy cover = 49 percent.

Region 3 —Santa Fe National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

132

Region 3 — Santa Fe National Forest 1
C

133

Initial conditions/no-action trajectoryThis stand has initial tree density of 571 trees per acre (tpa) composed of Douglas-fir, gambel oak, and ponderosa pine in the understory and ponderosa pine in the overstory. Canopy bulk density is 0.04 kg/m3 (0.0025 lb/ft3), and canopy base height is 8 ft, so ladder fuels and canopy fuels are not sufficient to enable crown fire initiation or spread. Woody fuel loading is 6 tons/ac, and litter and duff loading is 6 tons/ac. Although the predicted fire type is surface fire, potential flame lengths are 5 ft and potential basal area mortality is 66 percent for severe fire weather because fire behavior is predicted by using fuel model 5 suggesting the importance of brush fuels. The FFE model does not track brush fuels directly, so these results should be interpreted with caution. Canopy base height decreases and canopy bulk density increases over time as smaller trees grow into the overstory, and in 10 years passive crown fire becomes likely for severe and moderate fire weather. In 30 years, canopy base height begins to increase again as the trees grow and crowns rise causing the predicted fire type to become surface fire again for severe and moderate fire weather. There is little surface fuel accumulation over time, and flame lengths decline as the fuel model shifts from 5 to 9. 

Silvicultural and surface fuel treatments—long-term effectsAlthough the treatments have little effect on crown fire potential in the short term, they do reduce crown fire potential in the long term. In all treatments, canopy base height increases over time as the trees grow and the stand self-thins. Flame lengths remain high for severe fire weather, but the increase in canopy base height causes the predicted fire type to become surface fire in 10 years and remain surface fire for the duration of the 50-year projection. Potential flame lengths decrease in 20 years in the higher density treatments (200 tpa and 300 tpa) with a pile and burn or no surface fuel treatment as the fuel model shifts from 5 to 9. However, in the higher density treatments with prescribed fire, the additional tree mortality creates a more open stand with more brush fuels, and flame lengths remain above 5 ft for 40 years. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and reduces canopy bulk density slightly and consumes much of the surface fuels. However, many snags are created that contribute to surface fuel loading in 10 years. Thinning to 50 tpa or less is required to increase canopy base height and decrease canopy bulk density; all other treatments have little effect on stand structure. Potential flame lengths and basal area mortality remain high for severe fire weather in all treatments because fire behavior is predicted by using fuel model 5. Potential flame lengths and basal area mortality are low for moderate fire weather in all treatments. The pile and burn and prescribed fire surface fuel treatments reduce woody surface fuels to below initial levels, but potential flame lengths and basal area mortality remain high for severe fire weather because the predominant fuel model is 5. The prescribed fire surface fuel treatment causes the highest potential flame lengths and basal area mortality. 

Region 3 —Santa Fe National Forest 1
D

134Table 12a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 2 1 4 3 3 2

3–6 in 2 0 2 2 2 26–12 in 2 1 1 2 2 2>12 in 0 0 0 0 0 0Litter 2 0 2 2 2 2Duff 4 3 3 4 4 4

Flame length (ft) Moderate 1 1 1 1 1 1

Severe 5 6 2 5 5 5

Torching index Severe 19 20 112 17 19 19Crowning index Severe 52 66 90 59 52 52Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface

Potential basal area mortality (%) Moderate 33 25 14 31 33 33

Severe 66 70 26 71 66 66

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 0 1 1 1>12 in 0 0 0 0Litter 2 1 1 1Duff 2 3 4 4

Flame length (ft) Moderate 1 1 1 1

Severe 2 5 5 5

Torching index Severe 112 17 19 19Crowning index Severe 90 59 52 52Type of fire Moderate Surface Surface Surface Surface

Severe Surface Passive Surface Surface

Potential basal area mortality (%) Moderate 5 31 33 33

Severe 11 71 66 66

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 1 1 1 1>12 in 0 0 0 0Litter 0 0 0 0Duff 2 3 3 3

Flame length (ft) Moderate 1 1 1 1

Severe 1 6 6 6

Torching index Severe 120 18 20 20Crowning index Severe 96 73 66 66Type of fire Moderate Surface Surface Surface Surface

Severe Surface Passive Surface Surface

Potential basal area mortality (%) Moderate 5 23 25 25

Severe 8 73 70 70

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 3 — Santa Fe National Forest 1
E

135

Table 12b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 2 2 3 3 4 5 1 4 3 3 3 3

3–6 in 2 2 2 2 3 3 0 2 2 2 2 26–12 in 2 2 2 2 2 2 1 3 3 3 3 3>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 3 4 4 5 5 0 1 1 2 2 2Duff 4 4 4 5 5 5 3 3 3 3 3 3

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 1 1 1 1

Severe 5 5 3 3 3 3 6 5 5 5 5 4

Torching index Severe 19 0 0 14 35 46 20 60 72 81 90 100Crowning index Severe 52 43 38 35 32 30 66 71 63 57 54 52Type of fire Moderate Surface Passive Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 5 8 10 9 24 26 124 10 6 4 4 4

18–29.9 in 0 0 0 0 0 0 3 2 1 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 3 2 2 2 3 3 3 3 3 3 4

3–6 in 2 2 2 2 2 2 2 2 2 2 2 26–12 in 1 1 1 1 1 1 2 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 1 1 1 1 1 2 1 1 2 2 2Duff 3 3 3 3 3 3 4 4 4 4 4 4

Flame length (ft) Moderate 1 1 1 1 1 1 1 1 1 1 2 2

Severe 2 1 1 1 1 1 5 5 5 5 3 3

Torching index Severe 112 193 209 220 238 248 17 68 77 90 142 140Crowning index Severe 90 89 80 75 73 71 59 64 59 54 52 51Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 1 2 3 3 3 1 2 3 4 5 5

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 —Santa Fe National Forest 1
F

136Table 12b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 2 2 2 1 1 2 2 3 4

3–6 in 1 1 1 1 1 1 1 1 1 1 1 16–12 in 0 0 0 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 1 1 1 1 2 1 1 1 2 2 2Duff 2 2 2 2 2 3 3 3 3 3 3 4

Flame length (ft) Moderate 1 1 1 1 1 1 1 1 1 1 2 2

Severe 2 1 1 1 1 1 5 5 5 5 2 3

Torching index Severe 112 193 210 213 224 241 17 68 77 86 170 159Crowning index Severe 90 84 76 72 68 67 59 64 59 53 51 50Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 1 2 3 3 3 1 2 3 4 5 5

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 2 2 0 3 3 3 3 3

3–6 in 0 1 1 1 1 1 1 1 1 1 1 26–12 in 1 1 1 1 1 1 1 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 0 1 1 1 2 2 1 1 1 1 2 2Duff 2 2 2 2 2 2 3 3 3 3 3 3

Flame length (ft) Moderate 1 1 1 1 1 1 1 1 1 1 1 1

Severe 2 1 1 1 1 1 5 6 5 5 5 5

Torching index Severe 112 162 166 185 201 206 17 61 68 76 84 87Crowning index Severe 90 79 69 62 59 58 59 77 67 61 56 55Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 5 4 4 3 3 3 17 10 6 4 4 4

18–29.9 in 1 1 0 0 0 0 3 3 2 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Santa Fe National Forest 1
G

137

Table 12b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 2 3 3 4 4 2 2 3 3 3 4

3–6 in 2 2 2 2 2 2 2 2 2 2 2 26–12 in 2 2 2 2 2 2 2 2 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 2 2 2 3 3 3 2 2 3 3 4 4Duff 4 4 4 4 4 5 4 4 4 4 5 5

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 2 2 2 2

Severe 5 5 3 3 3 3 5 5 3 3 3 3

Torching index Severe 19 57 115 122 129 125 19 41 94 98 92 61Crowning index Severe 52 49 45 41 40 39 52 43 38 35 33 32Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 3 4 5 5 6 3 4 5 5 6 7

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 2 3 3 4 1 1 2 3 3 4

3–6 in 1 1 1 1 1 1 1 1 1 1 1 16–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 1 2 2 3 3 3 1 2 3 3 4 4Duff 4 4 4 4 4 4 4 4 4 4 4 4

Flame length (ft) Moderate 1 1 2 1 2 2 1 1 2 2 2 2

Severe 5 5 2 2 2 3 5 5 2 2 3 3

Torching index Severe 19 57 129 152 147 138 19 41 114 120 60 77Crowning index Severe 52 49 45 41 39 38 52 43 38 35 33 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 3 4 5 5 6 3 4 5 5 6 8

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 —Santa Fe National Forest 1
H

138

Table 12c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 571 561 551 543 517 494 104 103 101 99 97 95

Quadratic mean diameter (in) 5.0 5.7 6.3 6.8 7.4 7.9 5.0 11.0 12.3 13.5 14.5 15.4Total volume (ft 3) 1,188 1,655 2,144 2,618 3,038 3,435 1,067 1,265 1,671 2,071 2,461 2,832Merchantable volume (ft 3) 955 1,351 1,786 2,230 2,628 2,999 895 1,058 1,447 1,836 2,198 2,561Basal area (ft 2) 79 99 120 138 153 166 60 68 84 98 112 124

Stand density index 190 227 263 295 316 335 108 120 142 160 177 191Canopy closure (percent) 49 56 63 67 71 73 39 43 49 53 57 60Crown competition factor 67 82 98 112 122 131 49 55 66 76 84 92

Canopy base height (ft) 8 1 1 3 7 9 10 24 26 27 28 29Canopy bulk density (kg/m3) 0.04 0.05 0.06 0.07 0.08 0.09 0.03 0.03 0.03 0.04 0.04 0.04

Table 12b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 3 3 3 3 0 3 3 3 3 3

3–6 in 0 2 2 2 2 2 0 2 2 2 2 26–12 in 1 3 3 3 3 3 1 3 3 3 3 3>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 0 1 1 2 2 2 0 1 1 2 2 2Duff 3 3 3 3 3 3 3 3 3 3 3 3

Flame length (ft) Moderate 1 1 1 1 1 2 1 1 1 1 1 2

Severe 6 5 5 5 5 3 6 5 5 5 5 3

Torching index Severe 20 60 72 81 90 135 20 60 69 81 90 135Crowning index Severe 66 67 59 55 52 50 66 67 59 55 52 50Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 33 10 7 4 4 4 50 10 7 4 4 4

18–29.9 in 3 2 1 0 0 0 3 2 1 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Santa Fe National Forest 1
I

139

Table 12c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 571 50 64 63 62 60 59 100 106 104 102 100 98

Quadratic mean diameter (in) 5.0 12.8 12.7 14.1 15.2 16.3 17.2 11.1 12.0 13.2 14.2 15.1 15.9Total volume (ft3) 1,188 890 1,037 1,340 1,651 1,960 2,256 1,262 1,460 1,866 2,272 2,663 3,031

Merchantable volume (ft3) 955 765 908 1,206 1,509 1,810 2,098 1,048 1,219 1,615 2,010 2,390 2,747Basal area (ft2) 79 45 57 68 78 87 96 67 83 98 112 124 135Stand density index 190 75 95 108 121 132 142 118 142 162 179 194 206Canopy cover (percent) 49 30 35 39 43 46 49 42 49 54 57 60 63Crown competition factor 67 36 43 50 56 62 67 55 67 77 85 92 99Canopy base height (ft) 8 23 31 31 31 32 32 8 25 26 28 29 30Canopy bulk density (kg/m3) 0.04 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04

Pile and burn Trees per acre 571 50 72 70 69 68 66 100 110 108 106 104 102

Quadratic mean diameter (in) 5.0 12.8 12.0 13.3 14.4 15.4 16.3 11.1 11.8 12.9 13.9 14.8 15.6Total volume (ft3) 1,188 890 1,035 1,340 1,650 1,957 2,253 1,262 1,459 1,866 2,272 2,664 3,034Merchantable volume (ft3) 955 765 906 1,205 1,507 1,805 2,092 1,048 1,219 1,615 2,010 2,391 2,749Basal area (ft2) 79 45 57 68 78 87 96 67 83 98 112 124 135Stand density index 190 75 97 111 124 135 145 118 143 163 180 195 208Canopy cover (percent) 49 30 35 39 43 46 49 42 49 54 57 60 63Crown competition factor 67 36 43 50 56 62 67 55 67 77 85 92 99Canopy base height (ft) 8 23 31 31 30 30 31 8 25 26 27 29 30Canopy bulk density (kg/m3) 0.04 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.04 0.04

Prescribed fire Trees per acre 571 50 89 87 85 84 82 100 95 93 91 89 88

Quadratic mean diameter (in) 5.0 12.8 10.3 11.4 12.4 13.3 14.2 11.1 10.7 12.0 13.2 14.2 15.1Total volume (ft3) 1,188 821 956 1,243 1,540 1,837 2,123 977 1,153 1,521 1,885 2,240 2,575Merchantable volume (ft3) 955 708 841 1,121 1,409 1,695 1,968 821 979 1,338 1,691 2,035 2,360Basal area (ft2) 79 45 51 61 71 81 90 67 60 73 86 98 109Stand density index 190 75 92 107 120 133 144 118 106 125 142 157 170Canopy cover (percent) 49 30 32 36 40 44 47 42 38 43 48 51 55Crown competition factor 67 36 39 45 52 58 63 55 48 57 65 72 79Canopy base height (ft) 8 23 28 26 27 28 29 10 26 27 28 29 30Canopy bulk density (kg/m3) 0.04 0.02 0.02 0.03 0.03 0.03 0.04 0.03 0.02 0.03 0.03 0.04 0.04

Region 3 —Santa Fe National Forest 1
J

140Table 12c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 571 200 200 197 193 189 186 300 299 294 289 284 277

Quadratic mean diameter (in) 5.0 8.5 9.5 10.4 11.2 12 12.6 7.0 7.8 8.6 9.2 9.8 10.4Total volume (ft3) 1,188 1,428 1,654 2,116 2,577 3,019 3,440 1,429 1,656 2,127 2,596 3,047 3,464Merchantable volume (ft3) 955 1,179 1,355 1,789 2,233 2,660 3,064 1,180 1,357 1,799 2,248 2,681 3,083

Basal area (ft2) 79 79 99 117 133 148 161 79 99 117 135 150 163Stand density index 190 154 185 210 233 252 269 167 200 229 255 277 295Canopy cover (percent) 49 49 56 61 65 68 71 49 56 61 66 69 72

Crown competition factor 67 67 81 94 105 114 123 67 81 95 107 117 126

Canopy base height (ft) 8 8 19 21 23 25 25 8 14 18 19 18 14Canopy bulk density (kg/m3) 0.04 0.04 0.05 0.05 0.06 0.06 0.06 0.04 0.06 0.06 0.07 0.08 0.09

Pile and burn Trees per acre 571 200 202 198 195 191 187 300 301 296 291 286 279

Quadratic mean diameter (in) 5.0 8.5 9.5 10.4 11.2 11.9 12.5 7.0 7.8 8.5 9.2 9.8 10.4

Total volume (ft3) 1,188 1,428 1,654 2,116 2,577 3,020 3,441 1,429 1,656 2,127 2,596 3,047 3,463Merchantable volume (ft3) 955 1,179 1,355 1,789 2,233 2,660 3,065 1,180 1,357 1,799 2,248 2,681 3,082

Basal area (ft2) 79 79 99 117 133 148 161 79 99 117 135 150 163Stand density index 190 154 185 211 233 253 269 167 201 229 255 277 296Canopy cover (percent) 49 49 56 61 65 68 71 49 56 61 66 69 72

Crown competition factor 67 67 81 94 105 114 123 67 81 95 107 117 126

Canopy base height (ft) 8 8 19 21 23 25 25 8 14 18 19 10 14Canopy bulk density (kg/m3) 0.04 0.04 0.05 0.05 0.06 0.06 0.06 0.04 0.06 0.06 0.07 0.08 0.09

Prescribed fire Trees per acre 571 200 115 113 110 108 106 300 115 113 110 108 106

Quadratic mean diameter (in) 5.0 8.5 10.4 11.7 12.8 13.8 14.6 7.0 10.4 11.7 12.8 13.8 14.6Total volume (ft3) 1,188 1,067 1,264 1,669 2,072 2,465 2,837 1,067 1,264 1,671 2,074 2,467 2,843

Merchantable volume (ft3) 955 894 1,058 1,445 1,837 2,201 2,563 895 1,058 1,447 1,838 2,208 2,569Basal area (ft2) 79 79 68 84 99 112 124 79 68 84 99 112 124Stand density index 190 154 123 145 164 181 196 167 123 145 164 181 196Canopy cover (percent) 49 49 43 49 53 57 60 49 43 49 53 57 60

Crown competition factor 67 67 55 66 76 84 92 67 55 66 76 84 92Canopy base height (ft) 8 10 24 26 27 28 29 10 24 25 27 28 29Canopy bulk density (kg/m3) 0.04 0.03 0.03 0.03 0.04 0.04 0.04 0.03 0.03 0.04 0.04 0.04 0.04

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Santa Fe National Forest 1
K

141

Table 12d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 100 0 0 0 0 0 0 5 100 0 0 0 0 0 0

10 5 92 10 8 0 0 0 0 5 96 10 4 0 0 0 0

20 9 81 10 19 0 0 0 0 5 94 10 6 0 0 0 0

30 9 72 10 28 0 0 0 0 5 94 10 6 0 0 0 0

40 9 61 10 39 0 0 0 0 5 91 10 9 0 0 0 0

50 10 52 9 48 0 0 0 0 5 87 10 13 0 0 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 91 10 9 0 0 0 0 5 99 10 1 0 0 0

10 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

20 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

30 8 100 0 0 0 0 0 0 5 97 10 3 0 0 0

40 8 100 0 0 0 0 0 0 9 90 10 10 0 0 0

50 8 100 0 0 0 0 0 0 9 83 10 17 0 0 0

Pile and burn 1 8 91 10 9 0 0 0 0 5 100 0 0 0 0 0

10 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

20 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

30 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

40 8 100 0 0 0 0 0 0 9 100 0 0 0 0 0

50 8 100 0 0 0 0 0 0 9 92 10 8 0 0 0

Prescribed fire 1 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

10 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

20 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

30 8 100 0 0 0 0 0 0 5 100 0 0 0 0 0

40 8 100 0 0 0 0 0 0 5 99 10 1 0 0 0

50 8 100 0 0 0 0 0 0 5 95 10 5 0 0 0

Region 3 —Santa Fe National Forest 1
L

142

Region 3 — Santa Fe National Forest 1

Table 12f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 12e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 19 87 3 5 12 16 50 100Moderate—75th percentile 8 69 5 7 16 19 125 150Table 12d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 5 100 0 0 5 100 0 0

10 5 99 10 1 5 96 10 4

20 9 95 10 5 9 90 10 10

30 9 88 10 12 9 82 10 18

40 9 79 10 21 9 73 10 27

50 9 70 10 30 9 62 10 38

Pile and burn 1 5 100 0 0 5 100 0 0

10 5 100 0 0 5 100 0 0

20 9 100 0 0 9 100 0 0

30 9 100 0 0 9 96 10 4

40 9 91 10 9 9 85 10 15

50 9 80 10 20 9 71 10 29

Prescribed fire 1 5 100 0 0 5 100 0 0

10 5 100 10 0 5 99 10 1

20 5 96 10 4 5 96 10 4

30 5 95 10 5 5 94 10 6

40 5 91 10 9 5 91 10 9

50 9 87 10 13 9 87 10 13

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

143

Site: Elevation = 5,400 ft, slope = 15 percent, aspect = 360°.Species (based on trees per acre): Ponderosa pine (Pinus ponderosa) = 68 percent, gambel oak (Quercus gambelii) = 19 percent, mountain juniper (Juniperus scopulorum) = 12 percent.

Stand attributes: Stem density = 838 tpa, basal area = 87 ft2/ac, top height = 46 ft, stand density index = 221, quadratic mean diameter = 4.4 in, crown competition factor = 72, canopy cover = 51 percent.

Region 3 —Santa Fe National Forest 2
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

144

Region 3 — Santa Fe National Forest 2
C

145

Initial conditions/no-action trajectoryThis stand has initial tree density of 838 trees per acre (tpa) composed of gambel oak, juniper, and ponderosa pine in the understory and a ponderosa pine overstory. Canopy base height is only 3 ft, and canopy bulk density is 0.07 kg/m3 (0.0044 lb/ft3), so initial conditions have high potential for passive crown fire but low potential for active crown fire spread under severe fire weather. Potential tree mortality is 61 percent for severe fire but only 10 percent for moderate fire weather. Woody fuel loading is 6 tons/ac, and litter and duff loading is 7 tons/ac. With no action, canopy base height will increase as the trees grow and the stand self-thins, making passive crown fire unlikely in 20 yrs, but flame lengths increase as surface fuels accumulate.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment initially reduces surface fuels but has little effect on canopy base height and canopy bulk density. Passive crown fire remains likely after treatment, but potential flame lengths and basal area mortality are lower than initial conditions. Thinning to 100 tpa or less is needed to increase canopy base height and decrease canopy bulk density. The low-density treatments decrease crown fire potential (predicted fire type changes to surface fire) and basal area mortality, but activity fuels generated from the thinning prevent potential flame lengths from decreasing with treatment. The pile and burn surface fuel treatment and, to a greater extent, the prescribed fire treatment reduce surface fuels to below initial conditions. These surface fuel treatments further decrease crown fire potential, flame lengths, and basal area mortality for severe and moderate fire weather in the low-density treatments. Surface fuel treatments also decrease potential flame lengths and basal area mortality in the higher density treatments, but canopy base height is still low enough that passive crown fire remains likely for severe fire weather. 

Silvicultural and surface fuel treatments—long-term effectsThe prescribed fire only treatment increases canopy base height over time as the trees grow and the stand self-thins. In 10 years, the predicted fire type changes to surface fire for severe and moderate fire weather and remains surface fire for the 50-year projection. Surface fuels accumulate slowly, and potential flame lengths increase slightly over time. Regeneration in the low-density treatments causes a decrease in canopy base height in 20 years, and passive crown fire becomes likely. In reality, the decrease in canopy base height may not be as extreme or sudden as the model predicts, but generally regeneration in the more open stands can be expected to increase crown fire potential and another treatment may be necessary. Canopy base height continues to increase in the high-density treatments, and the predicted fire type changes from passive to surface fire in 10 years. In the high-density treatments with pile and burn or no surface fuel treatment, surface fuels accumulate and flame lengths increase, and passive crown fire is predicted again in 20 to 30 years. At this time, a second treatment would be necessary to reduce surface fuels. The high-density treatments with prescribed fire have a long-term effect on crown fire potential, because both surface fuels and regeneration are low. 

Region 3 —Santa Fe National Forest 2
D

146Table 13a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 2 1 4 4 3 3

3–6 in 2 0 3 3 2 26–12 in 2 1 3 2 2 2>12 in 0 0 0 0 0 0Litter 3 1 3 3 3 3Duff 4 3 4 4 4 4

Flame length (ft) Moderate 1 1 2 1 1 1

Severe 2 1 2 2 2 2

Torching index Severe 17 18 47 52 10 11Crowning index Severe 35 44 59 58 58 50Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 10 6 8 9 10 11

Severe 61 11 12 14 17 20

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 3 3 3 3Duff 3 3 3 3

Flame length (ft) Moderate 2 1 1 1

Severe 2 2 2 2

Torching index Severe 47 52 10 11Crowning index Severe 59 58 58 50Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 3 4 5 6

Severe 6 7 9 10

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 0 0 0 06–12 in 1 1 1 1>12 in 0 0 0 0Litter 1 1 1 1Duff 3 3 3 3

Flame length (ft) Moderate 1 1 1 1

Severe 1 1 1 1

Torching index Severe 88 86 17 17Crowning index Severe 63 62 61 61Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 3 4 5 5

Severe 5 7 9 9

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 3 — Santa Fe National Forest 2
E

147

Table 13b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 2 3 4 5 6 7 1 2 3 4 5 6

3–6 in 2 2 3 3 3 4 0 1 1 1 2 26–12 in 2 2 2 2 2 2 1 2 1 1 2 2>12 in 0 0 0 0 0 1 0 0 0 0 1 1Litter 3 4 4 5 5 5 1 3 4 5 5 5Duff 4 4 4 4 5 5 3 3 3 3 3 4

Flame length (ft) Moderate 1 2 2 2 2 2 1 1 2 2 2 2

Severe 2 3 3 3 3 3 1 1 3 3 3 3

Torching index Severe 17 12 21 38 52 62 18 30 19 29 41 54Crowning index Severe 35 29 30 31 34 35 44 37 33 35 35 36Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 14 16 38 47 39 31 61 7 12 31 37 31

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 3 3 4 4 4 4 3 3 4 4 5

3–6 in 3 3 3 3 4 4 3 3 3 3 3 46–12 in 3 3 3 3 3 2 2 3 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 3 2 3 4 4 4 3 3 4 4 4 5Duff 4 4 4 4 4 5 4 4 4 4 4 5

Flame length (ft) Moderate 2 2 2 2 2 2 1 2 2 2 2 2

Severe 2 3 3 3 3 3 2 3 3 3 3 3

Torching index Severe 47 82 0 18 15 32 52 18 0 8 20 32Crowning index Severe 59 53 51 49 43 36 58 53 51 45 36 34Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Passive Passive Surface Surface Passive Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 6 4 2 3 3 3 7 5 3 4 4 4

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 —Santa Fe National Forest 2
F

148Table 13b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 2 3 4 4 1 2 2 3 4 5

3–6 in 1 1 1 2 2 2 1 1 1 2 2 26–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 3 2 3 4 4 4 3 3 4 4 4 5Duff 3 4 4 4 4 4 3 4 4 4 4 4

Flame length (ft) Moderate 2 1 1 1 2 2 1 1 1 2 2 2

Severe 2 1 1 2 3 3 2 1 1 3 3 3

Torching index Severe 47 111 0 25 15 31 52 26 0 8 20 31Crowning index Severe 59 53 51 49 43 36 58 53 51 45 36 34Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Surface Passive Surface Surface Surface Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 6 4 2 3 3 3 7 5 3 4 4 4

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 2 3 3 4 0 1 2 3 4 4

3–6 in 0 1 1 1 2 2 1 1 1 1 2 26–12 in 1 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 0 1 1 1 0 0 0 0 1 1Litter 1 2 3 3 4 4 3 2 3 4 4 4Duff 3 3 3 3 3 3 3 3 3 3 3 3

Flame length (ft) Moderate 1 1 1 1 2 2 1 1 1 1 2 2

Severe 2 1 1 2 3 3 2 1 1 2 3 3

Torching index Severe 50 115 0 25 18 22 56 106 0 24 19 24Crowning index Severe 59 55 52 51 44 40 58 55 53 47 38 37Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Surface Passive Surface Surface Surface Passive Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 6 2 3 3 3 2 10 2 3 3 3 3

18–29.9 in 1 1 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 — Santa Fe National Forest 2
G

149

Table 13b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 3 3 4 5 5 3 3 3 4 5 6

3–6 in 2 3 3 3 3 4 2 3 3 3 3 46–12 in 2 3 2 2 2 2 2 3 2 2 2 2>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 3 3 4 4 4 5 3 3 4 4 5 5Duff 4 4 4 4 4 5 4 4 4 4 4 5

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 2 2 2 2

Severe 2 2 3 3 3 3 2 2 3 3 3 3

Torching index Severe 10 19 33 15 21 30 11 21 14 16 23 34Crowning index Severe 58 54 51 49 41 39 50 54 49 43 37 37Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Passive Surface Surface Passive Surface Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 8 6 5 5 5 5 9 8 8 8 13 22

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 2 2 3 4 5 1 2 3 4 5 5

3–6 in 1 1 1 2 2 2 1 1 1 2 2 26–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 0 0 0 0 0 0 0 0Litter 3 3 4 4 4 5 3 3 4 4 5 5Duff 3 4 4 4 4 4 3 4 4 4 4 4

Flame length (ft) Moderate 1 1 1 2 2 2 1 1 2 2 2 2

Severe 2 1 2 3 3 3 2 1 3 3 3 3

Torching index Severe 10 28 44 15 20 34 11 30 16 16 22 37Crowning index Severe 58 54 51 49 41 39 50 54 49 43 37 37Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Passive Surface Surface Passive Surface Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 8 6 5 5 5 5 9 8 8 8 13 22

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 3 —Santa Fe National Forest 2
H

150

Table 13c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 838 822 782 738 703 676 613 607 595 563 530 504

Quadratic mean diameter (in) 4.4 5.0 5.7 6.3 6.9 7.4 4.4 5.5 6.2 6.9 7.6 8.2Total volume (ft 3) 1,493 1,928 2,378 2,858 3,377 3,924 1,601 1,815 2,257 2,709 3,189 3,670

Merchantable volume (ft 3) 1,315 1,662 2,007 2,474 2,930 3,589 1,427 1,601 1,957 2,392 2,903 3,447Basal area (ft 2) 87 114 139 162 183 203 90 102 126 147 166 184Stand density index 221 274 318 355 389 419 213 235 278 312 340 365Canopy closure (percent) 51 62 69 74 78 81 52 57 65 70 74 77Crown competition factor 72 96 118 136 153 169 73 83 104 121 135 149

Canopy base height (ft) 3 5 7 10 12 13 3 4 7 9 11 13Canopy bulk density (kg/m3) 0.07 0.09 0.09 0.08 0.08 0.07 0.05 0.07 0.08 0.07 0.07 0.07

Table 13b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 3 4 4 0 2 2 3 4 5

3–6 in 0 1 1 1 2 2 0 1 1 1 2 26–12 in 1 2 2 2 2 2 1 2 2 2 2 2>12 in 0 0 0 0 1 1 0 0 0 0 1 1Litter 1 3 3 4 4 4 1 3 3 4 4 5Duff 3 3 3 3 3 3 3 3 3 3 3 3

Flame length (ft) Moderate 1 1 1 1 2 2 1 1 1 2 2 2

Severe 1 1 2 2 3 3 1 1 2 3 3 3

Torching index Severe 17 26 35 31 18 31 17 28 44 15 20 34Crowning index Severe 61 55 53 52 46 44 61 55 53 48 41 38Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Passive Surface Passive Surface Surface Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 17 3 4 4 4 4 24 4 6 6 6 5

18–29.9 in 0 0 0 0 0 0 0 0 0 0 0 030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Santa Fe National Forest 2
I

151

Table 13c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 838 50 274 272 271 269 267 100 323 320 318 315 312

Quadratic mean diameter (in) 4.4 15.6 7.1 7.8 8.4 9.0 9.7 11.5 6.9 7.5 8.1 8.8 9.4Total volume (ft3) 1,493 1,547 1,714 2,148 2,521 2,930 3,376 1,594 1,773 2,221 2,617 3,049 3,520Merchantable volume (ft3) 1,315 1,459 1,636 2,001 2,354 2,695 3,027 1,489 1,676 2,054 2,433 2,802 3,159Basal area (ft2) 87 66 76 90 103 119 136 72 84 99 115 132 151Stand density index 221 102 160 181 204 227 253 125 179 203 229 256 283Canopy cover (percent) 51 38 42 50 57 63 69 42 46 54 61 67 73Crown competition factor 72 48 54 69 84 99 117 54 62 78 94 111 129Canopy base height (ft) 3 13 16 1 4 6 10 13 4 1 4 7 9Canopy bulk density (kg/m3) 0.07 0.03 0.04 0.04 0.05 0.05 0.07 0.04 0.04 0.04 0.05 0.07 0.08

Pile and burn Trees per acre 838 50 274 272 271 269 267 100 323 320 318 315 312

Quadratic mean diameter (in) 4.4 15.6 7.1 7.8 8.4 9.0 9.7 11.5 6.9 7.5 8.1 8.8 9.4Total volume (ft3) 1,493 1,547 1,714 2,148 2,521 2,930 3,376 1,594 1,773 2,221 2,617 3,049 3,520Merchantable volume (ft3) 1,315 1,459 1,636 2,001 2,354 2,695 3,027 1,489 1,676 2,054 2,433 2,802 3,159Basal area (ft2) 87 66 76 90 103 119 136 72 84 99 115 132 151Stand density index 221 102 160 181 204 227 253 125 179 203 229 256 283Canopy cover (percent) 51 38 42 50 57 63 69 42 46 54 61 67 73Crown competition factor 72 48 54 69 84 99 117 54 62 78 94 111 129Canopy base height (ft) 3 13 16 1 4 6 10 13 4 1 4 7 9Canopy bulk density (kg/m3) 0.07 0.03 0.04 0.04 0.05 0.05 0.07 0.04 0.04 0.04 0.05 0.07 0.08

Prescribed fire Trees per acre 838 50 269 267 266 264 262 100 303 301 299 296 294

Quadratic mean diameter (in) 4.4 15.6 7.0 7.6 8.2 8.9 9.6 11.5 6.9 7.5 8.1 8.8 9.4Total volume (ft3) 1,493 1,466 1,634 2,054 2,415 2,819 3,263 1,509 1,680 2,108 2,490 2,906 3,367Merchantable volume (ft3) 1,315 1,384 1,562 1,915 2,255 2,589 2,932 1,415 1,594 1,955 2,317 2,666 3,013Basal area (ft2) 87 66 71 84 98 114 131 72 78 92 107 124 142Stand density index 221 102 151 172 194 218 244 125 166 189 214 239 267Canopy cover (percent) 51 38 40 48 55 61 68 42 43 52 58 65 71Crown competition factor 72 48 51 65 79 95 113 54 57 72 88 104 123Canopy base height (ft) 3 14 17 1 4 7 9 13 15 1 4 7 9Canopy bulk density (kg/m3) 0.07 0.03 0.04 0.04 0.04 0.05 0.07 0.03 0.04 0.04 0.05 0.06 0.07

Region 3 —Santa Fe National Forest 2
J

152Table 13c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 838 200 271 267 263 259 255 300 369 362 356 345 326

Quadratic mean diameter (in) 4.4 8.4 7.9 8.6 9.4 10.0 10.7 7.0 7.0 7.7 8.4 9.0 9.7Total volume (ft3) 1,493 1,623 1,812 2,239 2,662 3,102 3,558 1,635 1,840 2,287 2,730 3,178 3,596Merchantable volume (ft3) 1,315 1,487 1,669 2,060 2,521 2,945 3,369 1,486 1,664 2,046 2,540 2,978 3,402

Basal area (ft2) 87 76 92 109 126 143 160 80 98 117 136 154 168Stand density index 221 150 185 211 237 261 285 169 207 238 268 293 311Canopy cover (percent) 51 44 50 57 63 67 71 47 54 61 67 71 74Crown competition factor 72 58 70 84 98 112 125 63 77 94 110 124 135Canopy base height (ft) 3 3 4 6 6 7 10 3 4 6 6 7 10Canopy bulk density (kg/m3) 0.07 0.04 0.04 0.04 0.05 0.06 0.06 0.04 0.04 0.05 0.05 0.07 0.07

Pile and burn Trees per acre 838 200 271 267 263 259 255 300 369 362 356 345 326

Quadratic mean diameter (in) 4.4 8.4 7.9 8.6 9.4 10.0 10.7 7.0 7.0 7.7 8.4 9.0 9.7Total volume (ft3) 1,493 1,623 1,812 2,239 2,662 3,102 3,558 1,635 1,840 2,287 2,730 3,178 3,596Merchantable volume (ft3) 1,315 1,487 1,669 2,060 2,521 2,945 3,369 1,486 1,664 2,046 2,540 2,978 3,402

Basal area (ft2) 87 76 92 109 126 143 160 80 98 117 136 154 168Stand density index 221 150 185 211 237 261 285 169 207 238 268 293 311Canopy cover (percent) 51 44 50 57 63 67 71 47 54 61 67 71 74Crown competition factor 72 58 70 84 98 112 125 63 77 94 110 124 135Canopy base height (ft) 3 3 4 6 6 7 10 3 4 6 6 7 10Canopy bulk density (kg/m3) 0.07 0.04 0.04 0.04 0.05 0.06 0.06 0.04 0.04 0.05 0.05 0.07 0.07

Prescribed fire Trees per acre 838 200 225 221 218 215 212 300 296 291 286 281 278

Quadratic mean diameter (in) 4.4 8.4 8.3 9.1 9.8 10.5 11.2 7.0 7.4 8.2 8.9 9.6 10.2

Total volume (ft3) 1,493 1,536 1,715 2,118 2,519 2,935 3,366 1,551 1,740 2,161 2,578 3,016 3,477Merchantable volume (ft3) 1,315 1,420 1,595 1,989 2,400 2,799 3,196 1,423 1,596 1,968 2,421 2,858 3,293Basal area (ft2) 87 76 84 99 115 130 146 80 89 106 123 141 158Stand density index 221 150 166 189 212 234 255 169 183 210 237 263 288Canopy cover (percent) 51 44 47 53 59 64 68 47 50 57 62 67 72Crown competition factor 72 58 63 76 88 101 113 63 68 83 98 112 126Canopy base height (ft) 3 3 4 5 5 7 10 3 4 6 6 7 10Canopy bulk density (kg/m3) 0.07 0.03 0.04 0.04 0.04 0.05 0.05 0.03 0.04 0.04 0.05 0.06 0.06

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 3 — Santa Fe National Forest 2
K

153

Table 13d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 94 10 6 8 100 0 0

10 9 77 10 23 8 99 10 1

20 9 60 10 40 9 81 10 19

30 10 60 9 40 9 63 10 37

40 10 75 9 25 10 54 9 46

50 10 88 9 12 10 69 9 31

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 63 11 37 8 73 11 27

10 8 78 10 22 8 78 10 22

20 8 74 10 26 8 72 10 28

30 8 65 10 35 9 62 10 38

40 9 56 10 44 9 50 10 50

50 10 53 9 47 10 60 9 40

Pile and burn 1 8 63 11 37 8 73 11 27

10 8 100 0 0 8 100 0 0

20 8 100 0 0 8 96 10 4

30 8 87 10 13 9 81 10 19

40 9 74 10 26 9 67 10 33

50 9 63 10 37 9 55 10 45

Prescribed fire 1 8 100 0 0 8 100 0 0

10 8 100 0 0 8 100 0 0

20 8 100 0 0 8 98 10 2

30 8 89 10 11 8 84 10 16

40 9 76 10 24 9 69 10 31

50 9 65 10 35 9 58 10 42

Region 3 —Santa Fe National Forest 2
L

154

Region 3 — Santa Fe National Forest 2

Table 13f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 13e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 19 87 3 5 12 16 50 100Moderate—75th percentile 8 69 5 7 16 19 125 150Table 13d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 79 11 21 8 82 11 18

10 8 78 10 22 8 78 10 22

20 8 70 10 30 9 69 10 31

30 9 59 10 41 9 56 10 44

40 10 52 9 48 10 55 9 45

50 10 62 9 38 10 69 9 31

Pile and burn 1 8 79 11 21 8 82 11 18

10 8 100 0 0 8 100 0 0

20 8 93 10 7 9 91 10 9

30 9 77 10 23 9 74 10 26

40 9 64 10 36 9 60 10 40

50 9 52 10 48 10 55 9 45

Prescribed fire 1 8 100 0 0 8 100 0 0

10 8 100 0 0 8 100 0 0

20 8 94 10 6 8 94 10 6

30 8 80 10 20 9 78 10 22

40 9 68 10 32 9 64 10 36

50 9 56 10 44 9 53 10 47

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

155

Appendix 4—Fuel Treatment Scenarios for the Intermountain Region (Region 4)

Site: Elevation = 5,000 ft, slope = 23 percent, aspect = 225°.Species (based on trees per acre): Ponderosa pine (Pinus ponderosa) = 2 percent, Engelmann spruce (Picea engelmannii) = 38 percent, grand fir (Abies grandis) = 56 percent, Douglas-fir (Pseudotsuga menziesii) = 4 percent, western larch (Larix occidentalis) = <1 percent.

Stand attributes: Stem density = 2,079 tpa, basal area = 240 ft2/ac, top height = 103 ft, stand density index = 598, quadratic mean diameter = 4.6 in, crown competition factor = 74, canopy cover = 52 percent.

Region 4 — Payette National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

156

Region 4 — Payette National Forest 1
C

157

Initial conditions/no-action trajectoryThis stand is composed of Ponderosa pine, Engelmann spruce, grand fir, Douglas-fir, and western larch with 2,079 trees per acre (tpa). Canopy bulk density is 0.27 kg/m3 (0.0169 lb/ft3), and canopy base height is 2 ft, so ladder fuels are not sufficient to enable crown fire initiation, but canopy fuels are sufficient to enable active crown fire spread for severe fire weather. Woody fuel loading is 18 tons/ac, and litter and duff loading is 27 tons/ac. Predicted flame lengths are 3 ft, and potential basal area mortality is 100 percent for severe fire weather and 25 percent for moderate fire weather. With no action, canopy base height increases slightly and canopy bulk density decreases as trees grow and the stand self-thins. However surface fuels accumulate causing higher flame lengths, so crown fire potential increases over time. In 20 years, passive crown fire is likely for moderate fire weather, and active crown fire remains likely for severe fire weather for the 50-year projection. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and decreases canopy bulk density and surface fuel loading, which reduces crown fire potential and flame lengths, but many snags are created that contribute to high surface fuel loading and increase crown fire potential in 10 years. All thinning treatments reduce canopy bulk density and increase canopy base height, but the higher density treatments (200 and 300 tpa) increase canopy base height by only 1 ft. Activity fuels from thinning increase potential flame lengths in all treatments; the greater the thinning, the greater is the increase in surface fuel loading. In the 200 tpa treatment the increase in canopy base height is not enough to compensate for greater potential flame lengths, so passive crown fire remains likely for severe fire weather, and potential basal area mortality is 82 percent. The pile and burn surface fuel treatment and, to a greater extent, the prescribed fire treatment reduce surface fuel loading, so potential flame lengths and basal area mortality are lower. The reduction in potential flame lengths is sufficient to change the predicted fire type to surface fire in the 200 tpa treatment. 

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, fallen snags contribute to higher surface fuel loading in 10 years and potential flame lengths increase, but canopy base height continues to increase, so crown fire potential remains low for the 50-year trajectory. Regeneration in the 50 tpa treatment causes canopy base height to decrease in 20 years, but potential flame lengths are low, so crown fire remains unlikely for the 50-year projection regardless of surface fuel treatment. In the 100 tpa, 200 tpa, and 300 tpa treatments, regeneration causes canopy base height to decrease in 30 years, and potential flame lengths are high enough that passive crown fire is predicted for severe fire weather. At this time, another treatment would be necessary to decrease crown fire potential. However canopy base height increases over time as regeneration grows, and in 50 years the predicted fire type becomes surface fire again, but potential flame lengths are at least 4 ft for severe fire weather.

Region 4 — Payette National Forest 1
D

158Table 14a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 4 1 13 9 7 6

3–6 in 7 1 4 4 4 36–12 in 7 3 3 3 3 3>12 in 0 0 0 0 0 0Litter 2 1 5 4 4 4Duff 25 17 5 5 5 5

Flame length (ft) Moderate 2 1 4 3 2 2

Severe 3 2 6 4 4 3

Torching index Severe 2 109 80 99 16 23Crowning index Severe 12 34 41 32 30 26Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Passive Surface

Potential basal area mortality (%) Moderate 25 14 8 11 16 19

Severe 100 14 15 13 82 21

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 2

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 5 4 4 3Duff 5 5 5 5

Flame length (ft) Moderate 2 1 1 1

Severe 3 2 2 2

Torching index Severe 245 291 75 77Crowning index Severe 41 32 30 26Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 8 11 15 17

Severe 8 11 15 18

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 1Duff 4 4 4 4

Flame length (ft) Moderate 1 1 1 1

Severe 2 2 2 2

Torching index Severe 368 365 176 125Crowning index Severe 44 35 34 34Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 7 11 12 13

Severe 7 11 12 13

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 4 — Payette National Forest 1
E

159

Table 14b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 7 10 10 10 10 1 6 6 6 6 6

3–6 in 7 7 8 8 9 9 1 3 4 4 5 56–12 in 7 7 8 9 10 11 3 7 8 8 8 9>12 in 0 1 3 6 10 14 0 2 4 6 9 11Litter 2 4 4 4 4 4 1 2 3 3 3 3Duff 25 25 25 25 26 26 17 17 18 18 18 18

Flame length (ft) Moderate 2 3 4 4 4 5 1 2 2 3 3 4

Severe 3 4 5 6 6 7 2 4 4 4 5 5

Torching index Severe 2 0 0 0 0 0 109 60 90 109 120 125Crowning index Severe 12 13 16 17 19 20 34 30 28 28 28 29Type of fire Moderate Surface Surface Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Severe Active Active Active Active Active Active Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 339 448 394 317 238 177 548 41 35 31 31 29

18–29.9 in 4 6 11 14 16 17 6 7 9 11 12 1330–36 in 1 1 2 2 2 3 1 1 1 2 2 2

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 13 6 4 3 4 4 9 6 5 5 6 6

3–6 in 4 4 4 4 4 5 4 4 5 5 5 66–12 in 3 3 4 4 4 3 3 3 4 5 5 6>12 in 0 1 1 2 3 5 0 1 2 4 7 9Litter 5 2 2 2 2 2 4 2 2 3 3 2Duff 5 5 6 6 6 6 5 5 6 6 6 7

Flame length (ft) Moderate 4 2 2 2 2 2 3 2 2 2 2 3

Severe 6 3 3 3 3 3 4 3 3 4 4 5

Torching index Severe 80 272 22 36 42 44 99 227 238 16 17 21Crowning index Severe 41 40 40 41 41 42 32 29 28 29 29 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 22 28 17 75 74 52 26 32 26 63 64 48

18–29.9 in 3 3 4 6 7 7 3 4 7 10 12 1330–36 in 1 1 1 1 1 1 1 1 1 1 2 2

Region 4 — Payette National Forest 1
F

160Table 14b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 3 3 3 4 2 3 5 5 6 6

3–6 in 1 2 2 2 3 3 1 2 2 3 4 46–12 in 1 2 3 3 3 3 1 2 3 4 4 5>12 in 0 1 1 2 3 5 0 1 2 4 7 9Litter 5 2 2 2 2 2 4 2 2 3 3 3Duff 5 5 5 5 5 5 5 5 5 5 6 6

Flame length (ft) Moderate 2 1 1 1 2 2 1 1 2 2 2 3

Severe 3 2 2 2 2 3 2 2 3 3 4 4

Torching index Severe 245 554 45 53 55 55 291 427 309 23 22 25Crowning index Severe 41 40 40 41 41 42 32 29 28 29 29 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 22 28 18 82 81 57 26 33 27 68 67 51

18–29.9 in 3 3 4 5 7 7 3 4 7 10 12 1330–36 in 1 1 1 1 1 1 1 1 1 1 2 2

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 3 3 4 0 3 4 4 5 5

3–6 in 1 2 2 2 3 3 1 2 3 3 4 46–12 in 2 3 4 4 3 3 2 4 6 6 6 6>12 in 0 1 3 4 5 6 0 2 4 6 8 10Litter 1 1 2 2 2 2 4 2 2 2 2 2Duff 4 4 4 4 4 4 5 4 4 4 5 5

Flame length (ft) Moderate 1 1 1 2 2 2 1 1 2 2 2 3

Severe 2 2 2 2 3 3 2 2 3 3 4 4

Torching index Severe 368 510 37 42 47 49 365 376 17 18 19 14Crowning index Severe 44 43 43 43 44 44 35 33 32 32 32 32Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 25 33 22 91 87 61 41 43 30 79 76 55

18–29.9 in 5 5 6 6 6 6 5 6 7 9 10 1130–36 in 1 1 1 1 1 1 1 1 1 1 2 2

Region 4 — Payette National Forest 1
G

161

Table 14b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 7 6 7 7 7 7 6 6 7 8 8 8

3–6 in 4 4 5 5 6 6 3 3 4 5 6 76–12 in 3 3 5 6 7 8 3 3 5 6 7 8>12 in 0 1 3 5 8 12 0 1 3 5 9 13Litter 4 3 3 3 3 3 4 3 3 3 3 3Duff 5 5 6 6 7 7 5 5 6 6 7 7

Flame length (ft) Moderate 2 2 2 3 3 4 2 2 2 3 4 4

Severe 4 3 4 4 5 6 3 3 4 5 5 6

Torching index Severe 16 71 90 7 9 13 23 72 83 11 71 69Crowning index Severe 30 27 25 25 26 26 26 25 25 25 25 24Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Passive Passive Surface Surface Surface Surface Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 33 42 39 74 76 59 40 54 53 81 80 65

18–29.9 in 3 5 9 12 14 15 4 6 9 13 16 1630–36 in 1 1 1 2 2 2 1 1 1 2 2 3

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 4 6 7 7 7 2 4 7 8 8 8

3–6 in 1 2 3 3 4 5 1 2 3 4 5 66–12 in 1 2 3 5 6 7 1 2 4 5 6 7>12 in 0 1 2 5 8 12 0 1 3 5 9 13Litter 4 3 3 3 3 3 3 3 3 3 3 3Duff 5 5 5 6 6 6 5 5 5 6 6 7

Flame length (ft) Moderate 1 1 2 2 3 4 1 1 2 3 3 4

Severe 2 2 3 4 5 5 2 2 3 4 5 6

Torching index Severe 75 129 114 12 11 87 77 122 101 7 8 75Crowning index Severe 30 27 25 25 26 27 26 25 25 25 25 24Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Surface Surface Surface Surface Passive Passive Surface

Hard snags (stems/ac) 0–17.9 in 33 43 40 78 80 61 40 55 53 83 84 67

18–29.9 in 3 5 8 12 14 15 4 6 9 13 15 1630–36 in 1 1 1 2 2 2 1 1 1 2 2 2

Region 4 — Payette National Forest 1
H

162

Table 14c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,079 1,544 1,176 888 680 533 171 163 148 135 123 112

Quadratic mean diameter (in) 4.6 5.6 6.6 7.7 8.9 10.1 4.6 15.3 16.7 17.9 19.2 20.4Total volume (ft 3) 7,514 8,635 9,521 10,280 10,953 11,568 7,088 7,652 8,655 9,517 10,281 10,959Merchantable volume (ft 3) 6,777 7,716 8,375 8,924 9,392 10,321 6,620 7,184 8,124 8,924 9,640 10,404Basal area (ft 2) 240 265 279 288 293 297 197 208 224 236 246 253Stand density index 598 611 604 585 563 543 312 322 336 344 348 350

Canopy closure (percent) 91 93 93 94 94 93 81 83 84 85 86 87Crown competition factor 236 260 271 274 274 272 167 174 186 193 198 201Canopy base height (ft) 2 3 3 4 5 5 6 10 17 24 30 34Canopy bulk density (kg/m3) 0.27 0.25 0.19 0.17 0.15 0.14 0.07 0.08 0.09 0.09 0.09 0.09

Table 14b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 4 5 5 5 6 0 4 5 5 6 6

3–6 in 1 3 3 4 4 5 1 3 4 4 5 56–12 in 2 5 7 7 7 7 2 5 7 7 7 7>12 in 0 2 4 6 8 11 0 2 4 6 8 11Litter 1 2 3 3 3 3 1 2 3 3 3 3Duff 4 4 4 4 5 5 4 4 4 4 5 5

Flame length (ft) Moderate 1 2 2 2 3 3 1 2 2 2 3 3

Severe 2 3 3 4 4 5 2 3 3 4 4 5

Torching index Severe 176 193 208 12 13 18 125 94 102 10 12 12Crowning index Severe 34 30 29 28 29 30 34 31 29 29 29 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Surface Surface Surface Surface Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 60 44 33 84 80 59 81 46 35 87 84 62

18–29.9 in 5 6 8 10 11 12 5 6 8 10 12 1330–36 in 1 1 1 1 2 2 1 1 1 1 2 2

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 4 — Payette National Forest 1
I

163

Table 14c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,079 50 332 321 240 176 134 100 264 251 197 151 121

Quadratic mean diameter (in) 4.6 22.5 9.2 9.9 11.8 14.3 16.8 18.6 12.1 12.8 14.9 17.4 19.7Total volume (ft3) 7,514 5,664 6,133 7,015 7,846 8,613 9,315 7,431 8,003 9,023 9,934 10,746 11,459Merchantable volume (ft3) 6,777 5,419 5,886 6,733 7,532 8,267 8,922 7,062 7,634 8,632 9,527 10,291 10,996Basal area (ft2) 240 138 154 170 184 196 206 189 209 226 239 249 257Stand density index 598 183 292 313 315 312 307 271 357 375 374 367 361Canopy cover (percent) 91 65 69 72 75 76 78 79 81 83 84 85 86Crown competition factor 236 106 117 128 138 145 150 154 167 178 185 191 195Canopy base height (ft) 2 29 38 3 4 5 6 20 28 33 4 5 7Canopy bulk density (kg/m3) 0.27 0.05 0.06 0.05 0.05 0.05 0.05 0.08 0.09 0.09 0.09 0.08 0.08

Pile and burn Trees per acre 2,079 50 361 349 260 189 141 100 282 268 207 158 126

Quadratic mean diameter (in) 4.6 22.5 8.8 9.4 11.4 13.8 16.3 18.6 11.7 12.4 14.5 17.0 19.4Total volume (ft3) 7,514 5,664 6,134 7,020 7,854 8,623 9,328 7,431 8,005 9,030 9,950 10,767 11,491Merchantable volume (ft3) 6,777 5,419 5,887 6,741 7,540 8,284 8,959 7,062 7,635 8,634 9,530 10,336 11,033Basal area (ft2) 240 138 154 170 183 195 205 189 210 226 239 250 258Stand density index 598 183 296 318 320 315 309 271 361 380 378 371 364Canopy cover (percent) 91 65 69 72 75 76 78 79 81 83 84 85 86Crown competition factor 236 106 117 128 137 144 150 154 167 178 185 191 195Canopy base height (ft) 2 29 38 3 4 5 6 20 28 33 4 5 7Canopy bulk density (kg/m3) 0.27 0.05 0.06 0.06 0.05 0.05 0.05 0.08 0.09 0.09 0.09 0.09 0.08

Prescribed fire Trees per acre 2,079 50 391 377 277 202 151 100 325 310 233 173 134

Quadratic mean diameter (in) 4.6 22.5 8.2 8.8 10.8 13.1 15.5 18.6 10.4 11.1 13.2 15.8 18.3Total volume (ft3) 7,514 5,311 5,769 6,630 7,448 8,211 8,917 6,782 7,345 8,376 9,303 10,134 10,869Merchantable volume (ft3) 6,777 5,083 5,537 6,358 7,144 7,854 8,494 6,448 7,015 8,025 8,913 9,715 10,414Basal area (ft2) 240 138 145 161 175 188 198 189 191 209 223 234 243Stand density index 598 183 287 310 312 310 306 271 345 367 366 359 352Canopy cover (percent) 91 65 66 70 73 75 77 79 78 80 82 83 84Crown competition factor 236 106 109 122 131 139 145 154 150 162 171 177 182Canopy base height (ft) 2 29 38 3 4 5 6 23 31 3 4 5 7Canopy bulk density (kg/m3) 0.27 0.05 0.05 0.05 0.05 0.05 0.05 0.07 0.07 0.08 0.08 0.08 0.07

Region 4 — Payette National Forest 1
J

164Table 14c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,079 200 333 312 253 202 168 300 392 359 296 243 206

Quadratic mean diameter (in) 4.6 13.9 11.3 12.2 13.8 15.8 17.6 11.6 10.7 11.6 13.0 14.6 16.1Total volume (ft3) 7,514 7,904 8,503 9,555 10,480 11,301 12,036 7,988 8,577 9,609 10,496 11,293 12,010Merchantable volume (ft3) 6,777 7,388 7,969 8,935 9,766 10,643 11,457 7,346 7,878 8,750 9,465 10,296 11,301Basal area (ft2) 240 210 234 251 265 275 283 219 244 262 274 283 291Stand density index 598 339 408 426 427 421 415 379 436 453 453 447 442Canopy cover (percent) 91 84 86 88 89 89 90 86 88 90 91 91 91Crown competition factor 236 182 197 209 217 222 226 197 216 229 237 241 244Canopy base height (ft) 2 4 9 15 4 5 25 4 9 15 5 21 24Canopy bulk density (kg/m3) 0.27 0.08 0.10 0.10 0.10 0.10 0.09 0.10 0.10 0.11 0.11 0.11 0.11

Pile and burn Trees per acre 2,079 200 348 326 263 207 171 300 404 371 306 249 210

Quadratic mean diameter (in) 4.6 13.9 11.1 11.9 13.6 15.6 17.4 11.6 10.5 11.4 12.8 14.4 15.9Total volume (ft3) 7,514 7,904 8,504 9,547 10,469 11,292 12,030 7,988 8,578 9,606 10,503 11,302 12,018Merchantable volume (ft3) 6,777 7,388 7,970 8,940 9,755 10,655 11,485 7,346 7,879 8,745 9,480 10,276 11,272Basal area (ft2) 240 210 234 251 264 275 283 219 244 262 274 284 291Stand density index 598 339 411 430 429 423 417 379 438 456 456 450 444Canopy cover (percent) 91 84 86 88 89 89 90 86 88 90 91 91 91Crown competition factor 236 182 197 209 217 222 226 197 216 229 237 242 245Canopy base height (ft) 2 4 9 15 4 5 25 4 9 15 4 5 24Canopy bulk density (kg/m3) 0.27 0.08 0.10 0.10 0.10 0.10 0.09 0.10 0.10 0.11 0.11 0.11 0.11

Prescribed fire Trees per acre 2,079 200 346 329 250 188 147 300 368 349 268 204 161

Quadratic mean diameter (in) 4.6 13.9 10.4 11.1 13.2 15.5 17.9 11.6 10.1 10.9 12.8 15.0 17.2Total volume (ft3) 7,514 7,056 7,647 8,713 9,676 10,531 11,299 7,078 7,669 8,736 9,697 10,562 11,333Merchantable volume (ft3) 6,777 6,671 7,263 8,301 9,208 10,062 10,821 6,657 7,247 8,256 9,151 10,019 10,819Basal area (ft2) 240 210 203 221 236 247 257 219 206 224 239 251 261Stand density index 598 339 366 389 388 381 374 379 375 398 398 392 386Canopy cover (percent) 91 84 81 83 84 85 86 86 82 84 85 86 87Crown competition factor 236 182 164 177 186 192 197 197 169 183 192 199 204Canopy base height (ft) 2 10 20 30 4 5 7 7 11 16 4 5 6Canopy bulk density (kg/m3) 0.27 0.07 0.08 0.09 0.09 0.09 0.08 0.07 0.08 0.09 0.09 0.09 0.08

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 4 — Payette National Forest 1
K

165

Table 14d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 53 8 32 9 15 8 61 9 39 0 0

10 10 100 0 0 10 71 8 17 9 11

20 10 67 12 33 0 0 10 95 8 3 9 2

30 12 54 10 46 0 0 10 92 12 8 0 0

40 12 70 10 30 0 0 10 81 12 19 0 0

50 12 86 10 14 0 0 10 69 12 31 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 65 12 35 0 0 10 98 12 2 0 0

10 10 45 8 34 9 22 10 45 8 32 9 23

20 8 42 10 30 9 28 10 57 8 25 9 18

30 8 43 10 29 9 28 10 72 8 16 9 12

40 8 39 10 36 9 26 10 95 8 3 9 2

`50 10 46 8 32 9 22 10 88 12 12 0 0

Pile and burn 1 8 46 9 28 10 26 8 56 9 37 10 7

10 8 61 9 39 0 0 8 57 9 40 10 3

20 8 59 9 38 10 3 8 40 10 32 9 28

30 8 54 9 35 10 11 10 52 8 27 9 20

40 8 48 9 31 10 21 10 78 8 13 9 9

50 8 41 10 33 9 27 10 96 12 4 0 0

Prescribed fire 1 8 61 9 39 0 0 8 58 9 42 0 0

10 8 60 9 40 0 0 8 49 9 38 10 13

20 8 55 9 38 10 7 10 44 8 31 9 25

30 8 48 9 34 10 18 10 65 8 20 9 16

40 8 42 9 30 10 28 10 85 8 8 9 7

50 10 39 8 35 9 26 10 96 12 4 0 0

Region 4 — Payette National Forest 1
L

166

Region 4 — Payette National Forest 1

Table 14f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 14e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 20 85 3 5 8 15 50 100Moderate—75th percentile 11 69 6 7 10 18 125 150Table 14d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 74 8 16 9 9 10 55 8 29 9 16

10 10 47 8 33 9 19 10 47 8 35 9 18

20 10 78 8 14 9 8 10 88 8 8 9 4

30 10 97 12 3 0 0 10 88 12 12 0 0

40 10 80 12 20 0 0 10 69 12 31 0 0

50 10 62 12 38 0 0 12 52 10 48 0 0

Pile and burn 1 8 64 9 36 0 0 8 65 9 35 0 0

10 8 56 9 32 10 11 8 55 9 29 10 16

20 10 53 8 30 9 17 10 66 8 22 9 12

30 10 85 8 10 9 5 10 97 12 3 0 0

40 10 89 12 11 0 0 10 77 12 23 0 0

50 10 70 12 30 0 0 10 55 12 45 0 0

Prescribed fire 1 8 60 9 40 0 0 8 61 9 39 0 0

10 8 41 10 31 9 28 10 40 8 36 9 24

20 10 63 8 22 9 15 10 69 8 18 9 12

30 10 86 8 8 9 6 10 93 8 4 9 3

40 10 95 12 5 0 0 10 91 12 9 0 0

50 10 81 12 19 0 0 10 77 12 23 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

167

Site: Elevation = 4,800 ft, slope = 20 percent, aspect = 315°Species (based on trees per acre): Grand fir (Abies grandis) = 85 percent, ponderosa pine (Pinus ponderosa) = 6 percent, Douglas-fir (Pseudotsuga menziesii) = 8 percent.

Stand attributes: Stem density = 3,158 tpa, basal area = 289 ft2/ac, top height = 96 ft, stand density index = 754, quadratic mean diameter = 4.2 in, crown competition factor = 277, canopy cover = 94 percent.

Region 4 — Payette National Forest 2
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

168

Region 4 — Payette National Forest 2
C

169

Initial conditions/no-action trajectoryThis is a dense stand with 3,158 trees per acre (tpa) composed of Douglas-fir and grand fir understory with a low-density ponderosa pine overstory. Canopy bulk density is 0.17 kg/m3 (0.0106 lb/ft3), and canopy base height is 3 ft, so ladder fuels are not sufficient to enable crown fire initiation, but canopy fuels are sufficient to enable active crown fire spread for severe fire weather. Woody fuel loading is 9 tons/ac, and litter and duff loading is 8 tons/ac. Predicted flame lengths and potential basal area mortality are low for severe and moderate fire weather. With no action, canopy base height increases slightly and canopy bulk density decreases as trees grow and the stand self-thins, but surface fuels accumulate rapidly causing higher flame lengths and crown fire potential. In 10 years, the predicted fire type is active crown fire for severe fire weather and passive crown fire for moderate fire weather. In 40 years, canopy base height increases enough that the predicted fire type becomes passive crown fire for both moderate and severe fire weather.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and reduces canopy bulk density and surface fuel loading, which decreases crown fire potential. Thinning to 200 tpa or less is required to increase canopy base height and reduce canopy bulk density sufficiently to affect crown fire potential. Activity fuels from thinning treatments increase surface fuel loading, which causes higher potential flame lengths and basal area mortality; the greater the thinning, the greater are activity fuels. The pile and burn, and to a greater extent, the prescribed fire treatments reduce surface fuels, which decreases potential flame lengths and basal area mortality. The prescribed fire treatment also causes tree mortality, which increases canopy base height. This additional increase in canopy base height is sufficient to change the predicted fire type to surface fire in the 300 tpa treatment. 

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, surface fuel loading increases from fallen snags in 10 years, and potential flame lengths increase. Passive crown fire is likely again because the treatment does not increase canopy base height sufficiently to compensate for higher flame lengths associated with surface fuel accumulation. In 20 years, canopy base height increases and the predicted fire type is surface fire, but surface fuels continue to accumulate and potential flame lengths increase. In 50 years, potential flame lengths are 5 ft and 8 ft for moderate and severe fire weather respectively, so an additional treatment may be necessary to reduce surface fuels. In the 50 tpa treatment, regeneration causes canopy base height to decrease in 20 years and passive crown fire is likely again, but the effect is short lived and the predicted fire type changes to surface fire again in 30 years. In all other treatments, regeneration causes a decrease in canopy base height in 20 or 30 years, and passive crown fire remains likely for the duration of the 50-year projection. A second treatment would be necessary to decrease crown fire potential. Surface fuels accumulate over time, and flame lengths exceed 5 ft in 50 years for severe fire weather, so an additional surface fuel treatment may also be necessary to reduce tree mortality.

Region 4 — Payette National Forest 2
D

170Table 15a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 17 12 8 6

3–6 in 3 0 4 4 4 46–12 in 3 1 3 3 3 3>12 in 0 0 0 0 0 0Litter 3 2 7 7 6 5Duff 5 4 5 5 5 5

Flame length (ft) Moderate 1 1 5 4 2 2

Severe 2 2 7 5 4 3

Torching index Severe 38 55 69 111 125 53Crowning index Severe 18 21 43 29 21 18Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Surface Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 18 14 6 8 12 14

Severe 19 14 45 11 12 15

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 4 3 2 2

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 7 6 5 5Duff 5 5 5 5

Flame length (ft) Moderate 2 2 1 1

Severe 4 3 2 2

Torching index Severe 140 233 249 127Crowning index Severe 43 29 21 18Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 6 8 12 14

Severe 6 8 12 14

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 2Duff 4 4 4 4

Flame length (ft) Moderate 2 1 1 1

Severe 3 2 2 2

Torching index Severe 201 350 282 283Crowning index Severe 45 31 24 21Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 6 8 11 13

Severe 6 8 11 13

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 4 — Payette National Forest 2
E

171

Table 15b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 9 15 16 16 15 1 8 11 11 12 12

3–6 in 3 4 6 8 10 12 0 4 6 7 9 106–12 in 3 4 7 11 14 17 1 6 9 12 14 16>12 in 0 1 4 8 13 18 0 2 5 8 12 16Litter 3 8 7 7 7 6 2 5 5 5 5 4Duff 5 6 7 8 9 10 4 4 5 6 6 7

Flame length (ft) Moderate 1 3 4 5 6 6 1 3 4 5 5 5

Severe 2 4 6 7 8 9 2 4 6 7 7 8

Torching index Severe 38 0 0 0 0 0 55 12 36 52 54 59

Crowning index Severe 18 13 14 20 22 23 21 23 23 24 26 27

Type of fire Moderate Surface Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Severe Conditional Active Active Active Passive Passive Surface Passive Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 601 773 733 524 366 250 812 77 80 67 59 53

18–29.9 in 3 7 11 14 14 14 4 6 9 11 12 1230–36 in 0 0 1 1 1 2 0 0 0 1 1 1

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 17 9 6 6 6 7 12 8 7 8 8 9

3–6 in 4 5 5 5 6 7 4 4 5 6 7 86–12 in 3 3 4 4 4 4 3 4 5 5 6 7>12 in 0 1 2 2 3 5 0 1 2 4 6 9Litter 7 3 3 3 4 4 7 4 4 5 5 5Duff 5 6 6 7 7 7 5 6 6 7 7 8

Flame length (ft) Moderate 5 3 2 2 2 3 4 2 3 3 4 4

Severe 7 4 4 4 4 4 5 4 4 5 5 6

Torching index Severe 69 138 5 19 24 22 111 188 0 5 7 7Crowning index Severe 43 43 35 32 41 46 29 30 30 31 32 33Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 24 30 16 129 121 89 28 39 28 147 147 103

18–29.9 in 1 1 3 4 5 7 1 3 5 8 9 1130–36 in 0 0 0 0 1 1 0 0 0 1 1 1

Region 4 — Payette National Forest 2
F

172Table 15b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 4 3 4 4 6 7 3 4 5 7 8 9

3–6 in 1 2 2 3 4 5 1 2 3 4 5 66–12 in 1 2 3 3 3 3 1 2 3 4 5 6>12 in 0 1 1 2 3 5 0 1 2 4 6 9Litter 7 3 3 3 4 4 6 4 4 5 5 5Duff 5 5 5 6 6 7 5 5 6 6 7 7

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 3 4

Severe 4 3 3 3 3 4 3 3 3 4 5 6

Torching index Severe 140 225 17 28 29 29 233 263 10 10 10 5Crowning index Severe 43 43 33 30 39 46 29 30 30 31 32 33Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 24 31 16 137 129 95 28 40 28 157 160 111

18–29.9 in 1 1 3 4 5 7 1 3 5 8 9 1130–36 in 0 0 0 0 1 1 0 0 0 1 1 1

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 3 4 5 7 0 3 4 6 7 8

3–6 in 1 2 2 3 4 5 1 2 3 4 5 66–12 in 2 3 4 4 4 4 2 3 5 6 6 7>12 in 0 1 3 4 4 6 0 2 4 6 8 10Litter 1 2 3 3 4 4 6 4 4 4 5 4Duff 4 4 4 4 5 5 5 4 4 5 5 6

Flame length (ft) Moderate 2 1 2 2 2 3 1 2 2 3 3 4

Severe 3 2 3 3 4 4 2 3 3 4 5 6

Torching index Severe 201 266 17 26 27 27 350 271 9 8 4 5Crowning index Severe 45 44 32 29 38 43 31 31 32 32 33 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 28 35 18 143 134 99 40 49 30 165 163 114

18–29.9 in 3 3 4 4 5 7 3 4 6 7 9 1030–36 in 0 0 0 0 1 1 0 0 0 1 1 1

Region 4 — Payette National Forest 2
G

173

Table 15b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 8 8 10 11 11 11 6 8 11 12 12 13

3–6 in 4 5 6 7 8 10 4 4 6 8 10 116–12 in 3 4 6 8 11 12 3 4 7 10 13 15>12 in 0 1 3 6 10 15 0 1 3 7 11 16Litter 6 5 5 5 5 5 5 6 6 6 5 5Duff 5 6 6 7 8 9 5 6 6 7 8 9

Flame length (ft) Moderate 2 3 3 4 5 5 2 3 4 4 5 5

Severe 4 4 5 6 7 7 3 4 6 7 7 8

Torching index Severe 125 161 125 0 0 0 53 47 108 0 0 0Crowning index Severe 21 21 22 23 24 25 18 19 20 21 23 23Type of fire Moderate Surface Surface Surface Passive Passive Passive Surface Surface Surface Passive Passive Passive

Severe Surface Surface Surface Passive Passive Passive Cond. Cond. Surface Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 39 53 53 131 135 99 50 68 73 120 117 90

18–29.9 in 2 4 8 11 12 13 3 5 9 12 13 1330–36 in 0 0 0 1 1 2 0 0 0 1 1 2

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 5 8 10 11 11 2 6 10 11 12 12

3–6 in 1 2 4 5 7 8 1 2 4 6 8 106–12 in 1 2 5 7 9 11 1 2 5 8 11 14>12 in 0 1 3 6 10 15 0 1 3 7 11 16Litter 5 5 5 5 5 5 5 6 6 6 5 5Duff 5 5 6 6 7 8 5 5 6 7 7 8

Flame length (ft) Moderate 1 2 3 4 4 5 1 2 3 4 5 5

Severe 2 3 4 6 6 7 2 3 5 6 7 8

Torching index Severe 249 204 154 0 0 0 127 67 122 0 0 0Crowning index Severe 21 21 22 23 24 26 18 19 20 21 23 24Type of fire Moderate Surface Surface Surface Passive Passive Passive Surface Surface Surface Passive Passive Passive

Severe Surface Surface Surface Passive Passive Passive Cond. Cond. Cond. Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 39 54 54 138 144 105 50 68 73 125 123 93

18–29.9 in 2 4 8 11 12 13 3 5 9 12 13 1330–36 in 0 0 0 1 1 2 0 0 0 1 1 1

Region 4 — Payette National Forest 2
H

174

Table 15c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 3,158 2,221 1,512 1,053 742 537 321 292 248 213 185 163

Quadratic mean diameter (in) 4.1 5.0 6.1 7.3 8.8 10.3 4.1 12.7 14.0 15.3 16.5 17.7Total volume (ft 3) 8,386 9,128 9,715 10,264 10,791 11,282 7,963 8,400 9,169 9,835 10,441 10,970Merchantable volume (ft 3) 7,266 8,131 8,628 9,152 9,636 10,349 7,169 7,726 8,470 9,126 9,739 10,336

Basal area (ft 2) 289 303 308 309 310 310 252 258 267 272 276 278Stand density index 754 731 685 641 599 562 430 430 428 422 415 407

Canopy closure (percent) 94 95 95 95 94 94 89 89 89 89 89 89

Crown competition factor 277 296 296 292 289 282 219 221 224 224 225 222Canopy base height (ft) 3 3 4 4 5 5 4 5 14 21 24 28Canopy bulk density (kg/m3) 0.17 0.25 0.22 0.14 0.12 0.12 0.13 0.12 0.12 0.11 0.10 0.10

Table 15b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 5 7 9 10 11 0 6 8 10 11 11

3–6 in 1 3 4 6 7 8 1 4 6 7 9 106–12 in 2 5 8 10 12 13 2 6 9 12 13 15>12 in 0 2 4 8 11 14 0 2 5 8 11 15Litter 1 5 5 5 5 5 2 5 5 6 5 5Duff 4 4 5 5 6 7 4 4 5 5 6 7

Flame length (ft) Moderate 1 2 3 4 5 5 1 2 4 4 5 5

Severe 2 3 5 6 7 7 2 4 5 6 7 8

Torching index Severe 282 183 0 0 0 0 283 167 0 0 0 0

Crowning index Severe 24 23 23 24 25 27 21 21 22 22 24 25

Type of fire Moderate Surface Surface Passive Passive Passive Passive Surface Surface Passive Passive Passive Passive

Severe Surface Surface Passive Passive Passive Passive Surface Surface Passive Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 60 66 51 163 167 116 73 70 60 161 163 116

18–29.9 in 3 5 8 10 11 12 3 5 8 11 12 1230–36 in 0 0 0 1 1 1 0 0 0 1 1 1

tpa = trees per acre; d.b.h. = diameter at breast height; Cond. = conditional`.

Region 4 — Payette National Forest 2
I

175

Table 15c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 3,158 50 623 613 464 361 288 100 621 606 451 330 250

Quadratic mean diameter (in) 4.1 21.1 6.3 6.8 8.3 9.9 11.5 18.3 7.7 8.1 9.7 11.6 13.5Total volume (ft3) 8,386 4,602 5,026 5,863 6,680 7,473 8,249 6,595 7,103 8,033 8,898 9,688 10,403Merchantable volume (ft3) 7,266 4,405 4,812 5,567 6,338 7,017 7,587 6,290 6,757 7,637 8,473 9,214 9,885

Basal area (ft2) 289 122 137 156 174 191 207 183 199 217 230 241 250Stand density index 754 166 300 333 343 353 360 264 406 433 428 417 406Canopy cover (percent) 94 59 63 69 73 76 78 76 78 81 82 83 84Crown competition factor 277 90 100 117 130 143 153 143 152 166 173 178 182Canopy base height (ft) 3 33 34 3 5 6 7 32 34 3 4 5 6Canopy bulk density (kg/m3) 3.00 0.05 0.05 0.07 0.08 0.05 0.05 0.09 0.08 0.08 0.08 0.08 0.07

Pile and burn Trees per acre 3,158 50 659 648 490 380 302 100 668 652 486 353 266

Quadratic mean diameter (in) 4.1 21.1 6.2 6.7 8.1 9.6 11.3 18.3 7.4 7.8 9.3 11.2 13.2Total volume (ft3) 8,386 4,602 5,027 5,864 6,681 7,489 8,277 6,595 7,105 8,061 8,935 9,735 10,463Merchantable volume (ft3) 7,266 4,405 4,813 5,570 6,318 6,989 7,553 6,290 6,759 7,693 8,516 9,269 9,985

Basal area (ft2) 289 122 137 157 174 192 209 183 199 218 231 242 251Stand density index 754 166 303 337 348 358 365 264 411 440 435 424 413Canopy cover (percent) 94 59 63 69 73 76 79 76 78 81 82 83 84Crown competition factor 277 90 100 118 131 144 154 143 152 166 174 179 183Canopy base height (ft) 3 33 34 3 5 6 7 32 34 3 4 5 5Canopy bulk density (kg/m3) 3.00 0.05 0.05 0.07 0.08 0.06 0.05 0.09 0.08 0.08 0.08 0.08 0.07

Prescribed fire Trees per acre 3,158 50 695 684 519 403 319 100 704 689 510 373 282

Quadratic mean diameter (in) 4.1 21.1 5.9 6.4 7.7 9.3 10.9 18.3 7.0 7.4 8.9 10.7 12.6Total volume (ft3) 8,386 4,374 4,788 5,611 6,431 7,227 8,022 6,134 6,719 7,680 8,568 9,376 10,115Merchantable volume (ft3) 7,266 4,374 4,591 5,327 6,080 6,715 7,286 5,812 6,405 7,325 8,164 8,904 9,602Basal area (ft2) 289 122 130 151 169 188 206 183 188 208 222 234 244Stand density index 754 166 295 330 344 356 365 264 397 428 425 417 408Canopy cover (percent) 94 59 61 68 72 76 78 76 76 80 81 82 83Crown competition factor 277 90 95 114 128 142 153 143 143 159 167 173 178

Canopy base height (ft) 3 34 34 3 5 6 7 32 33 3 4 4 5

Canopy bulk density (kg/m3) 0.17 0.05 0.05 0.08 0.09 0.06 0.04 0.08 0.08 0.08 0.07 0.07 0.07

Region 4 — Payette National Forest 2
J

176Table 15c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 3,158 200 514 489 375 274 210 300 477 441 349 271 219

Quadratic mean diameter (in) 4.1 15.1 9.7 10.1 11.8 13.9 16.0 12.9 10.4 11.0 12.5 14.2 15.9Total volume (ft3) 8,386 8,237 8,716 9,558 10,347 11,077 11,732 8,709 9,153 9,938 10,676 11,338 11,915Merchantable volume (ft3) 7,266 7,717 8,192 9,015 9,774 10,524 11,157 7,711 8,392 9,199 9,975 10,618 11,209Basal area (ft2) 289 250 262 274 282 288 293 270 281 289 296 300 302Stand density index 754 389 488 500 485 464 446 449 507 511 497 478 461Canopy cover (percent) 94 88 88 89 89 89 89 91 91 91 91 91 91Crown competition factor 277 210 214 220 223 223 222 239 241 243 243 245 241Canopy base height (ft) 3 23 31 34 4 5 5 9 11 32 4 5 7Canopy bulk density (kg/m3) 3.00 0.14 0.13 0.13 0.12 0.11 0.10 0.17 0.15 0.14 0.13 0.12 0.11

Pile and burn Trees per acre 3,158 200 547 522 399 290 220 300 498 461 364 280 225

Quadratic mean diameter (in) 4.1 15.1 9.4 9.8 11.4 13.5 15.6 12.9 10.2 10.7 12.2 14.0 15.7Total volume (ft3) 8,386 8,237 8,718 9,565 10,358 11,096 11,761 8,709 9,155 9,941 10,680 11,328 11,912Merchantable volume (ft3) 7,266 7,717 8,194 9,059 9,827 10,570 11,227 7,711 8,393 9,195 9,957 10,623 11,232Basal area (ft2) 289 250 263 274 283 289 294 270 281 289 296 299 302Stand density index 754 389 494 507 492 470 451 449 512 516 501 481 463Canopy cover (percent) 94 88 88 89 89 89 89 91 91 91 91 91 91Crown competition factor 277 210 215 220 223 224 223 239 241 243 243 244 241Canopy base height (ft) 3 23 31 34 4 5 5 9 11 32 4 5 6Canopy bulk density (kg/m3) 3.00 0.14 0.13 0.13 0.12 0.11 0.10 0.17 0.15 0.14 0.13 0.12 0.11

Prescribed fire Trees per acre 3,158 200 642 619 462 328 244 300 640 611 461 334 252

Quadratic mean diameter (in) 4.1 15.1 8.3 8.7 10.3 12.4 14.6 12.9 8.5 9.0 10.5 12.5 14.5Total volume (ft3) 8,386 7,632 8,137 9,041 9,890 10,663 11,351 7,945 8,439 9,327 10,159 10,895 11,551

Merchantable volume (ft3) 7,266 7,632 7,655 8,564 9,378 10,157 10,847 7,945 7,840 8,726 9,536 10,287 10,948Basal area (ft2) 289 250 243 258 268 276 282 270 255 268 278 284 289Stand density index 754 389 478 498 486 464 446 449 497 513 499 477 458Canopy cover (percent) 94 88 86 87 88 88 88 91 88 89 89 90 90Crown competition factor 277 210 196 206 211 212 213 239 212 220 225 227 226Canopy base height (ft) 3 23 30 3 4 5 5 22 30 3 4 5 5Canopy bulk density (kg/m3) 3.00 0.11 0.12 0.11 0.11 0.11 0.10 0.13 0.13 0.13 0.12 0.11 0.10

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 4 — Payette National Forest 2
K

177

Table 15d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 48 8 47 10 5 9 56 8 44

10 10 87 12 13 0 0 10 90 12 10

20 12 76 10 24 0 0 12 51 10 49

30 12 85 13 15 0 0 12 80 10 20

40 12 58 13 42 0 0 12 96 13 4

50 13 65 12 35 0 0 12 75 13 25

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent

None 1 12 80 10 20 0 0 0 0 10 61 12 39 0 0

10 10 99 12 1 0 0 0 0 10 97 9 2 8 1

20 10 81 9 13 8 6 0 0 10 96 12 4 0 0

30 10 81 9 13 8 6 0 0 10 83 12 17 0 0

40 10 96 9 3 8 1 0 0 10 66 12 34 0 0

`50 10 88 12 12 0 0 0 0 12 54 10 46 0 0

Pile and burn 1 10 58 9 27 8 13 2 1 9 42 10 35 8 24

10 9 59 8 28 10 13 0 0 9 46 10 27 8 26

20 9 50 10 27 8 23 0 0 10 62 9 25 8 14

30 10 46 9 38 8 17 0 0 10 98 9 1 8 1

40 10 70 9 21 8 9 0 0 10 79 12 21 0 0

50 10 100 0 0 0 0 0 10 56 12 44 0 0

Prescribed fire 1 9 57 8 28 2 16 0 0 9 64 8 36 0 0

10 9 68 8 32 0 0 0 0 9 50 8 28 10 22

20 9 52 10 24 8 24 0 0 10 68 9 21 8 11

30 10 49 9 35 8 15 0 0 10 93 12 7 0 0

40 10 77 9 16 8 6 0 0 10 74 12 26 0 0

50 10 95 12 5 0 0 0 0 10 53 12 47 0 0

Region 4 — Payette National Forest 2
L

178

Region 4 — Payette National Forest 2

Table 15f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 15e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 20 85 3 5 8 15 50 100Moderate—75th percentile 11 69 6 8 11 18 125 150Table 15d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 94 9 4 8 2 10 65 9 19 8 16

10 10 98 12 2 0 0 10 96 12 4 0 0

20 10 68 12 32 0 0 10 56 12 44 0 0

30 12 61 10 39 0 0 12 78 10 22 0 0

40 12 87 10 13 0 0 12 90 13 10 0 0

50 12 88 13 12 0 0 12 65 13 35 0 0

Pile and burn 1 9 54 8 38 10 8 9 54 8 46 0 0

10 10 54 9 27 8 19 10 65 9 19 8 16

20 10 89 12 11 0 0 10 75 12 25 0 0

30 10 54 12 46 0 0 12 64 10 36 0 0

40 12 76 10 24 0 0 12 100 0 0 0

50 12 96 13 4 0 0 12 73 13 27 0 0

Prescribed fire 1 9 60 8 40 0 0 9 57 8 43 0 0

10 10 66 9 20 8 14 10 94 9 4 8 2

20 10 80 12 20 0 0 10 62 12 38 0 0

30 12 54 10 46 0 0 12 71 10 29 0 0

40 12 79 10 21 0 0 12 100 0 0 0

50 12 95 13 5 0 0 12 78 13 22 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

179

Site: Elevation = 5,800 ft, slope = 25 percent, aspect = 135°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 62 percent, grand fir (Abies grandis) =33 percent, ponderosa pine (Pinus ponderosa) = 5 percent.

Stand attributes: Stem density = 2,144 tpa, basal area = 181 ft2/ac, top height = 67 ft, stand density index = 479, quadratic mean diameter = 3.9 in, crown competition factor = 242, canopy cover = 91 percent.

Region 4 — Payette National Forest 3
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

180

Region 4 — Payette National Forest 3
C

181

Initial conditions/no-action trajectoryThis is a dense stand with 2,144 trees per acre (tpa) composed of Douglas-fir and grand fir understory with a low-density ponderosa pine overstory. Canopy bulk density is 0.42 kg/m3 (0.0262 lb/ft3), and canopy base height is 3 ft, so ladder fuels are not sufficient to enable crown fire initiation. Canopy fuels are sufficient to enable crown fire spread for severe fire weather. Woody fuel loading is 11 tons/ac, and litter and duff loading is 12 tons/ac. Predicted flame lengths are low, and potential basal area mortality is about 40 percent for severe and moderate fire weather. With no action, canopy base height increases and canopy bulk density decreases slightly as trees grow and the stand selfthins, but surface fuels accumulate rapidly causing higher flame lengths, so crown fire potential increases. In 10 years, predicted fire type is active crown fire for severe fire weather and remains so for the duration of the 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment creates many snags and has little effect on crown fire potential because canopy base height does not increase and canopy bulk density is not reduced enough to prevent conditional crown fire for severe fire weather. All thinning treatments increase canopy base height to a similar height, but the greater the thinning, the greater is the reduction in canopy bulk density. The 300 tpa treatment does not reduce canopy bulk density sufficiently enough to prevent conditional crown fire for severe fire weather. In all treatments, extensive activity fuels increase potential flame lengths to at least 5 ft for moderate and severe fire weather, so passive crown fire remains likely and potential basal area mortality is higher than initial conditions. Surface fuel treatments are necessary to further decrease crown fire potential and flame lengths. The pile and burn, and to a greater extent, the prescribed fire treatments, reduce surface fuels, which decreases potential flame lengths and basal area mortality. However, even after surface fuel treatments are applied, flame lengths and potential basal area mortality remain greater than initial conditions, because fire behavior is predicted by using primarily fuel model 2, suggesting grass fuels greatly influence fire behavior following surface fuel treatments. These results should be interpreted cautiously because grass fuels are not tracked in FFE. 

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, surface fuel loading increases from fallen snags in 10 years and then declines again as fuels decompose, but flame lengths remain higher than initial conditions for the 50-year projection. Canopy base height increases as trees grow and the stand self-thins, but canopy bulk density remains high enough that conditional crown fire is predicted for the entire 50-year projection. In the thinned stands without surface fuel treatment, surface fuels decompose rapidly and passive crown fire becomes unlikely in 10 years. Regeneration causes a decrease in canopy base height in all thinned stands in 20 years; this increases the potential for passive crown fire in stands without surface fuel treatment or with prescribed fire, but crown fire potential declines again in 30 years. The thinned stands with a pile and burn surface fuel treatment can sustain only a surface fire and have the lowest flame lengths for the 50-year projection.

Region 4 — Payette National Forest 3
D

182Table 16a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 17 16 15 13

3–6 in 4 0 10 10 9 86–12 in 4 2 3 3 3 4>12 in 0 0 0 0 0 0Litter 2 1 6 6 6 5Duff 10 7 9 9 10 10

Flame length (ft) Moderate 1 1 6 5 5 5

Severe 2 2 8 8 7 7

Torching index Severe 51 49 14 14 18 23Crowning index Severe 8 18 51 42 25 18Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Conditional Passive Passive Passive Conditional

Potential basal area mortality (%) Moderate 39 24 24 27 30 33

Severe 43 25 90 92 85 49

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 4 4 4 3

3–6 in 3 3 3 26–12 in 1 1 1 1>12 in 0 0 0 0Litter 6 5 5 5Duff 8 8 9 9

Flame length (ft) Moderate 3 3 2 2

Severe 5 4 4 3

Torching index Severe 40 46 73 96Crowning index Severe 51 42 25 18Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Conditional

Potential basal area mortality (%) Moderate 9 11 16 19

Severe 23 24 23 24

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 3 3 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 0 0 0 0Duff 6 7 7 7

Flame length (ft) Moderate 4 3 3 3

Severe 6 6 6 6

Torching index Severe 48 48 49 52Crowning index Severe 72 69 63 58Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 5 6 6 7

Severe 18 18 19 21

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 4 — Payette National Forest 3
E

183

Table 16b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 7 12 14 14 14 1 9 8 8 8 8

3–6 in 4 4 5 7 9 12 0 5 5 6 6 76–12 in 4 3 3 3 4 5 2 2 2 2 3 3>12 in 0 0 1 1 3 4 0 0 1 1 2 3Litter 2 6 7 7 7 7 1 3 3 4 4 4Duff 10 11 11 12 13 14 7 7 8 8 9 9

Flame length (ft) Moderate 1 2 3 4 5 5 1 2 2 2 3 3

Severe 2 4 5 6 7 7 2 4 4 4 4 4

Torching index Severe 51 2 6 6 13 12 49 19 48 71 81 87Crowning index Severe 8 8 8 8 9 10 18 18 16 16 16 17Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Active Active Active Active Active Cond. Active Cond. Cond. Cond. Cond.

Hard snags (stems/ac) 0–17.9 in 246 369 460 358 263 199 447 51 78 68 59 51

18–29.9 in 1 2 4 5 6 6 1 2 2 3 3 430–36 in 0 0 1 1 2 2 0 0 1 1 1 1

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 17 9 6 4 4 5 16 9 6 5 5 5

3–6 in 10 9 9 8 8 8 10 9 8 8 8 86–12 in 3 3 3 2 2 2 3 3 3 3 3 3>12 in 0 0 0 0 1 2 0 0 0 0 1 2Litter 6 2 2 2 3 3 6 2 2 3 3 3Duff 9 10 10 10 10 11 9 10 10 10 11 11

Flame length (ft) Moderate 6 3 2 2 2 2 5 3 2 2 2 2

Severe 8 5 4 4 4 4 8 5 4 4 4 4

Torching index Severe 14 55 4 22 37 42 14 45 5 23 38 42Crowning index Severe 51 47 46 45 45 40 42 41 39 37 36 35

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Passive Surface Surface Surface Passive Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 6 5 54 51 39 5 10 10 59 58 46

18–29.9 in 0 1 1 1 2 3 0 1 1 2 2 430–36 in 0 0 0 0 1 1 0 0 0 1 1 1

Region 4 — Payette National Forest 3
F

184Table 16b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 4 3 3 3 4 5 4 3 3 3 4 5

3–6 in 3 3 3 3 3 4 3 3 3 3 3 46–12 in 1 1 1 1 1 1 1 1 1 1 1 1>12 in 0 0 0 0 1 2 0 0 0 0 1 2Litter 6 2 2 2 3 3 5 2 2 3 3 3Duff 8 8 9 9 9 9 8 9 9 9 9 10

Flame length (ft) Moderate 3 2 1 1 2 2 3 2 1 2 2 2

Severe 5 4 2 2 3 3 4 3 2 2 3 3

Torching index Severe 40 108 30 51 61 59 46 131 33 52 62 59Crowning index Severe 51 47 46 45 45 39 42 41 39 37 36 35

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 2 6 6 59 56 43 5 10 10 64 63 49

18–29.9 in 0 1 1 1 2 3 0 1 1 2 2 430–36 in 0 0 0 0 1 1 0 0 0 1 1 1

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 3 3 0 2 2 2 3 3

3–6 in 3 3 3 3 3 3 3 3 3 3 3 46–12 in 2 3 3 3 3 3 2 3 3 3 3 3>12 in 0 0 1 1 1 1 0 0 1 1 1 1Litter 0 1 1 2 2 2 5 1 1 2 2 2Duff 6 6 7 7 7 7 8 7 7 7 7 7

Flame length (ft) Moderate 4 3 3 2 2 2 3 3 3 2 2 2

Severe 6 6 5 3 3 3 6 5 4 3 3 3

Torching index Severe 48 71 11 34 59 58 48 72 12 35 58 57Crowning index Severe 72 65 49 48 50 44 69 63 48 48 48 44

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 19 16 7 55 53 41 31 14 6 56 53 41

18–29.9 in 1 1 1 1 1 2 1 1 1 1 2 230–36 in 0 0 0 0 1 1 0 0 0 0 1 1

Region 4 — Payette National Forest 3
G

185

Table 16b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 15 9 6 5 6 6 13 8 6 6 6 7

3–6 in 9 8 8 8 8 8 8 8 8 8 8 96–12 in 3 3 3 3 3 3 4 3 3 3 3 4>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 6 2 3 3 3 3 5 3 3 4 4 4Duff 10 11 11 11 11 12 10 11 11 11 12 12

Flame length (ft) Moderate 5 3 2 2 2 3 5 3 2 2 3 3

Severe 7 5 4 4 4 4 7 4 4 4 4 4

Torching index Severe 18 49 4 16 28 29 23 66 4 21 23 23Crowning index Severe 25 27 28 27 27 27 18 22 23 22 22 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Passive Passive Surface Surface Conditional Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 11 20 21 70 69 56 19 32 34 81 79 65

18–29.9 in 0 1 1 2 3 4 0 1 2 2 3 430–36 in 0 0 0 1 1 1 0 0 0 1 1 2

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 4 3 3 4 5 6 3 3 4 5 6 7

3–6 in 3 3 3 3 4 5 2 2 3 3 4 56–12 in 1 1 1 1 1 2 1 1 1 1 1 2>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 5 2 3 3 3 4 5 3 3 4 4 4Duff 9 9 10 10 10 10 9 9 10 10 10 11

Flame length (ft) Moderate 2 1 1 2 2 2 2 1 2 2 2 2

Severe 4 2 2 3 3 3 3 2 2 3 3 4

Torching index Severe 73 167 34 40 47 50 96 202 33 45 39 42Crowning index Severe 25 27 28 27 27 27 18 22 23 22 23 23Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Conditional Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 11 20 21 74 74 59 19 32 35 86 83 69

18–29.9 in 0 1 1 2 3 4 0 1 2 2 3 430–36 in 0 0 0 1 1 1 0 0 0 1 1 2

Region 4 — Payette National Forest 3
H

186

Table 16c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,144 1,705 1,299 1,010 802 650 506 461 397 345 302 267

Quadratic mean diameter (in) 3.9 4.7 5.6 6.5 7.5 8.4 3.9 7.2 8.3 9.3 10.3 11.3Total volume (ft 3) 3,633 4,316 4,910 5,489 6,056 6,601 3,120 3,415 4,014 4,584 5,142 5,691Merchantable volume (ft 3) 2,559 2,751 2,886 2,978 3,659 4,090 2,564 2,712 2,987 3,249 3,840 4,718

Basal area (ft 2) 181 209 223 234 244 250 122 132 150 164 176 187Stand density index 479 515 514 509 501 492 262 274 295 309 319 326Canopy closure (percent) 91 93 94 94 94 94 73 75 79 81 83 84Crown competition factor 242 272 280 285 287 286 130 139 156 168 177 185Canopy base height (ft) 3 3 5 6 9 10 3 5 9 13 16 20Canopy bulk density (kg/m3) 0.42 0.42 0.40 0.39 0.35 0.32 0.16 0.16 0.18 0.19 0.18 0.18

Table 16b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 2 2 3 4 0 4 3 3 3 4

3–6 in 2 4 4 4 4 4 2 4 4 4 4 56–12 in 2 3 3 3 3 2 2 3 3 3 2 2>12 in 0 0 1 1 1 2 0 0 1 1 1 2Litter 0 1 2 2 2 3 0 1 2 2 2 3Duff 7 7 7 7 8 8 7 7 7 8 8 8

Flame length (ft) Moderate 3 3 2 2 2 2 3 3 2 2 2 2

Severe 6 5 4 3 3 3 6 5 4 3 3 3

Torching index Severe 49 68 13 38 56 56 52 66 14 40 52 53Crowning index Severe 63 59 49 48 47 41 58 57 49 49 44 39Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 49 9 6 57 55 42 76 11 7 59 57 44

18–29.9 in 1 1 1 1 2 3 1 1 1 1 2 330–36 in 0 0 0 0 1 1 0 0 0 0 1 1

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 4 — Payette National Forest 3
I

187

Table 16c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,144 50 310 305 244 201 169 100 353 346 281 234 199

Quadratic mean diameter (in) 3.9 17.9 7.7 8.3 9.9 11.6 13.3 13.0 7.4 8.1 9.6 11.1 12.6Total volume (ft3) 3,633 2,923 3,179 3,706 4,287 4,919 5,577 2,990 3,260 3,838 4,460 5,115 5,780Merchantable volume (ft3) 2,559 2,769 3,011 3,509 4,023 4,560 5,052 2,768 3,004 3,475 3,966 4,696 5,225Basal area (ft2) 181 87 100 115 131 148 163 92 106 123 140 157 173

Stand density index 479 127 203 227 241 255 267 151 219 246 262 277 289Canopy cover (percent) 91 49 54 59 64 68 71 53 58 64 68 72 75

Crown competition factor 242 68 77 90 102 114 125 76 87 102 115 128 139Canopy base height (ft) 3 14 19 3 5 7 8 13 15 3 5 7 8Canopy bulk density (kg/m3) 0.42 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.07

Pile and burn Trees per acre 2,144 50 336 331 264 217 183 100 379 372 302 250 211

Quadratic mean diameter (in) 3.9 17.9 7.4 8.0 9.6 11.2 12.9 13.0 7.2 7.8 9.3 10.8 12.3Total volume (ft3) 3,633 2,923 3,180 3,715 4,295 4,920 5,586 2,990 3,261 3,844 4,474 5,138 5,826Merchantable volume (ft3) 2,559 2,769 3,012 3,512 4,034 4,534 5,027 2,768 3,004 3,488 3,991 4,703 5,267Basal area (ft2) 181 87 100 116 132 149 165 92 106 124 141 159 175

Stand density index 479 127 207 232 246 261 274 151 222 250 267 283 296Canopy cover (percent) 91 49 54 60 64 69 72 53 58 64 69 73 76Crown competition factor 242 68 77 91 103 116 127 76 87 103 117 130 142Canopy base height (ft) 3 14 19 3 5 7 8 13 15 3 5 7 8Canopy bulk density (kg/m3) 0.42 0.04 0.04 0.05 0.05 0.05 0.06 0.05 0.05 0.06 0.06 0.06 0.07

Prescribed fire Trees per acre 2,144 50 335 331 267 222 188 100 338 334 268 223 188

Quadratic mean diameter (in) 3.9 17.9 6.6 7.1 8.5 10.1 11.7 13.0 6.7 7.2 8.6 10.2 11.8Total volume (ft3) 3,633 2,574 2,753 3,120 3,548 4,075 4,697 2,601 2,786 3,166 3,602 4,146 4,774Merchantable volume (ft3) 2,559 2,463 2,643 2,984 3,331 3,656 4,278 2,486 2,671 3,023 3,378 3,730 4,337Basal area (ft2) 181 87 81 92 106 124 141 92 82 94 109 126 143

Stand density index 479 127 174 193 208 226 243 151 177 197 211 229 246Canopy cover (percent) 91 49 45 50 56 61 66 53 46 51 57 62 66Crown competition factor 242 68 59 70 81 95 107 76 61 72 83 97 109Canopy base height (ft) 3 27 29 3 5 7 9 25 27 3 5 7 9Canopy bulk density (kg/m3) 0.42 0.02 0.03 0.04 0.04 0.04 0.05 0.03 0.03 0.04 0.04 0.04 0.05

Region 4 — Payette National Forest 3
J

188Table 16c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,144 200 433 418 345 289 246 300 504 479 397 334 285

Quadratic mean diameter (in) 3.9 9.6 7.0 7.7 9.1 10.5 11.9 8.2 6.8 7.5 8.8 10.1 11.3Total volume (ft3) 3,633 3,112 3,405 4,053 4,732 5,456 6,152 3,227 3,535 4,203 4,933 5,643 6,344Merchantable volume (ft3) 2,559 2,760 2,984 3,429 3,826 4,786 5,528 2,753 2,960 3,353 3,732 4,494 5,655Basal area (ft2) 181 100 117 137 155 174 189 109 127 148 168 185 200Stand density index 479 187 246 278 296 313 323 217 272 304 324 339 349Canopy cover (percent) 91 60 65 71 75 78 80 65 70 76 79 82 84Crown competition factor 242 91 104 123 138 152 163 106 121 141 158 171 181Canopy base height (ft) 3 13 14 3 4 6 8 13 15 3 5 6 8Canopy bulk density (kg/m3) 0.42 0.10 0.09 0.09 0.09 0.09 0.09 0.15 0.12 0.12 0.12 0.12 0.12

Pile and burn Trees per acre 2,144 200 459 443 365 304 258 300 528 502 415 348 294

Quadratic mean diameter (in) 3.9 9.6 6.8 7.5 8.9 10.2 11.6 8.2 6.7 7.4 8.6 9.9 11.2Total volume (ft3) 3,633 3,112 3,406 4,040 4,731 5,446 6,153 3,227 3,536 4,211 4,935 5,655 6,340Merchantable volume (ft3) 2,559 2,760 2,984 3,415 3,836 4,786 5,585 2,753 2,960 3,359 3,716 4,716 5,636Basal area (ft2) 181 100 117 137 156 174 190 109 127 149 169 186 200Stand density index 479 187 249 281 300 316 328 217 275 308 328 343 352Canopy cover (percent) 91 60 65 71 75 78 80 65 70 76 80 82 84Crown competition factor 242 91 105 123 139 152 163 106 122 142 159 172 181

Canopy base height (ft) 3 13 14 3 4 6 8 13 15 3 5 6 8Canopy bulk density (kg/m3) 0.42 0.10 0.09 0.09 0.09 0.09 0.09 0.15 0.12 0.12 0.12 0.12 0.12

Prescribed fire Trees per acre 2,144 200 343 339 273 225 190 300 355 350 282 234 197

Quadratic mean diameter (in) 3.9 9.6 6.8 7.3 8.7 10.3 11.9 8.2 6.8 7.3 8.8 10.3 12.0Total volume (ft3) 3,633 2,650 2,847 3,255 3,724 4,296 4,934 2,702 2,913 3,353 3,858 4,435 5,094Merchantable volume (ft3) 2,559 2,527 2,719 3,099 3,491 3,873 4,426 2,562 2,761 3,172 3,589 3,984 4,581Basal area (ft2) 181 100 85 98 113 131 148 109 89 103 118 136 154Stand density index 479 187 183 203 218 237 253 217 190 213 229 247 263Canopy cover (percent) 91 60 47 53 58 63 68 65 49 55 60 65 69Crown competition factor 242 91 64 75 87 101 113 106 68 80 93 106 119

Canopy base height (ft) 3 22 24 3 5 7 8 20 21 3 5 7 8Canopy bulk density (kg/m3) 0.42 0.03 0.03 0.04 0.04 0.04 0.05 0.03 0.03 0.04 0.04 0.05 0.06

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 4 — Payette National Forest 3
K

189

Table 16d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 8 70 9 20 10 10 8 66 9 34 0 0

10 10 84 8 12 9 4 10 85 8 10 9 5

20 10 73 12 27 0 0 10 83 8 12 9 5

30 12 52 10 48 0 0 10 88 8 9 9 3

40 12 70 10 30 0 0 10 99 8 1 0

50 12 87 10 13 0 0 10 91 12 9 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent Percent

None 1 12 89 10 11 0 0 0 0 12 84 10 16 0 0 0 0

10 10 94 12 6 0 0 0 0 10 94 12 6 0 0 0 0

20 10 69 8 16 9 14 2 1 10 72 8 16 9 12 0 0

30 10 54 8 24 9 22 0 0 10 60 8 23 9 17 0 0

40 10 55 8 23 9 22 0 0 10 64 8 20 9 16 0 0

`50 10 65 9 18 8 17 0 0 10 76 8 13 9 11 0 0

Pile and burn 1 10 55 2 24 8 12 9 10 10 51 8 18 2 17 9 14

10 8 37 9 31 2 30 10 2 8 49 9 38 2 9 10 4

20 8 52 9 46 2 2 10 1 8 54 9 41 10 5 0 0

30 8 48 9 45 10 7 0 0 8 49 9 38 10 13 0 0

40 9 40 8 40 10 19 0 0 8 40 9 32 10 28 0 0

50 10 35 9 34 8 31 0 0 10 46 8 30 9 25 0 0

Prescribed fire 1 2 96 8 2 9 2 0 0 2 92 8 5 9 4 0 0

10 2 77 8 13 9 11 0 0 2 72 8 15 9 13 0 0

20 2 49 8 27 9 24 0 0 2 44 8 30 9 25 10 1

30 8 39 9 37 2 21 10 3 8 41 9 38 2 17 10 4

40 9 46 8 43 10 12 0 0 9 44 8 42 10 13 0 0

50 9 42 8 35 10 24 0 0 9 40 8 34 10 26 0 0

Region 4 — Payette National Forest 3
L

190

Region 4 — Payette National Forest 3

Table 16f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 16e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 20 85 3 5 10 15 50 100Moderate—75th percentile 11 69 6 8 15 18 125 150Table 16d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent Percent

None 1 12 72 10 28 0 0 0 0 12 58 10 42 0 0 0 0

10 10 96 12 4 0 0 0 0 10 99 12 1 0 0 0 0

20 10 77 8 14 9 9 0 0 10 78 8 14 9 7 0 0

30 10 71 8 18 9 11 0 0 10 79 8 14 9 7 0 0

40 10 80 8 12 9 7 0 0 10 93 8 5 9 2 0 0

50 10 97 8 2 9 1 0 0 10 92 12 8 0 0 0 0

Pile and burn 1 10 44 8 33 9 22 2 1 8 40 10 36 9 23 0 0

10 8 57 9 36 10 7 0 0 8 59 9 32 10 9 0 0

20 8 54 9 33 10 12 0 0 8 53 9 28 10 19 0 0

30 8 47 9 28 10 25 0 0 8 43 10 35 9 21 0 0

40 10 43 8 36 9 21 0 0 10 57 8 29 9 14 0 0

50 10 64 8 23 9 13 0 0 10 81 8 13 9 6 0 0

Prescribed fire 1 2 84 8 8 9 7 0 0 2 76 8 13 9 11 0 0

10 2 57 8 18 9 15 10 10 2 42 10 21 8 20 9 17

20 2 34 8 32 9 27 10 7 8 35 9 30 2 21 10 14

30 8 43 9 39 10 9 2 8 8 44 9 40 10 15 0 0

40 9 42 8 41 10 18 0 0 9 38 8 38 10 24 0 0

50 9 37 8 32 10 31 0 0 10 39 9 33 8 29 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

191

Appendix 5—Fuel Treatment Scenarios for the Pacific Southwest Region (Region 5)

Region 5 — Plumas National Forest

Site: Elevation = 5,100 ft, slope = 10 percent, aspect = 180°.Species (based on trees per acre): Hardwoods = 56 percent, white fir (Abies concolor) = 43 percent, ponderosa pine (Pinus ponderosa) = 1 percent.

Stand attributes: Stem density = 1,427 tpa, basal area = 272 ft2/ac, top height = 85 ft, stand density index = 614, quadratic mean diameter = 5.9 in, crown competition factor = 169, canopy cover = 82 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

192

Region 5 — Plumas National Forest
C

193

Initial conditions/no-action trajectoryThis stand has 1,427 trees per acre (tpa) composed primarily of white fir and hardwoods with a low-density ponderosa pine overstory. Canopy bulk density is 0.23 kg/m3 (0.0144 lb/ft3), and canopy base height is 6 ft, so ladder fuels and canopy fuels are not sufficient to enable crown fire initiation or spread. Woody fuel loading is 14 tons/ac and litter and duff loading is 20 tons/ac. Potential flame lengths are less than 2 ft and potential basal area mortality is about 35 percent for moderate and severe fire weather. For the 50-year projection, canopy base height increases as the trees grow, and canopy bulk density declines as the stand self-thins, but surface fuels accumulate rapidly contributing to higher flame lengths. In 20 years, predicted flame lengths are 7 ft and fire type is passive crown fire for severe fire weather. Surface fire is predicted again at 40 years owing to higher canopy base height, but predicted flame lengths are 6 and 8 ft for moderate and severe fire weather, respectively. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and decreases canopy bulk density and surface fuel loading, which reduces crown fire potential and flame lengths, but many snags are created, contributing to high surface fuel loading and increased crown fire potential in 10 years. The low density (50 and 100 tpa) thinning treatments create similar stand structures; both raise canopy base height and reduce canopy bulk density. The high-density treatments (200 and 300 tpa) also raise canopy base height but have little effect on canopy bulk density. All thinning treatments increase surface fuel loading; the greater the thinning the greater the surface fuel loading, so thinning without surface fuel treatment increases potential flame lengths and basal area mortality despite the changes in canopy base height. Surface fuel treatments are critical to reducing flame lengths and crown fire potential in this stand. The pile and burn treatment reduces surface fuels, but the lower density treatments still have higher surface fuel loadings and potential flame lengths than the initial conditions. In the higher density treatments, the pile and burn treatment decreases surface fuels and potential flame lengths to below that of the initial conditions. Prescribed fire reduces all size classes of surface fuels more than the pile and burn, but fuel model selection is not sensitive to this difference in surface fuel loading, so flame lengths and potential mortality are similar for the surface fuel treatment options.

Silvicultural and surface fuel treatments—long-term effectsRegeneration in the more open stands (50 and 100 tpa) causes canopy base height to decrease and crown fire potential to increase in 30 or 40 years, but passive crown fire is predicted only in the 50 tpa treatment with no surface fuel treatment because of higher flame lengths from residual activity fuels. Surface fire is the predicted fire type for the 50-year trajectory in all other treatments, but without further treatment, surface fuels accumulate and potential flame lengths increase over time.

Region 5 —Plumas National Forest
D

194Table 17a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 4 1 23 18 12 9

3–6 in 5 1 8 9 9 86–12 in 5 2 5 6 6 5>12 in 0 0 0 0 0 0Litter 4 2 1 1 2 3Duff 16 11 15 19 19 18

Flame length (ft) Moderate 1 1 6 5 3 2

Severe 2 1 8 6 5 3

Torching index Severe 125 456 24 36 51 89Crowning index Severe 14 18 30 18 15 14Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 34 26 19 19 27 30

Severe 35 26 96 93 49 37

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 6 4 3 2

3–6 in 2 3 3 26–12 in 1 2 2 2>12 in 0 0 0 0Litter 1 1 2 3Duff 13 17 17 16

Flame length (ft) Moderate 2 1 1 1

Severe 2 2 1 1

Torching index Severe 218 410 687 827Crowning index Severe 30 18 15 14Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 13 18 26 30

Severe 13 18 26 30

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 3 4 3 3>12 in 0 0 0 0Litter 1 1 2 2Duff 10 13 13 12

Flame length (ft) Moderate 1 1 2 1

Severe 1 1 2 1

Torching index Severe 494 521 358 651Crowning index Severe 32 21 18 18Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 12 16 22 24

Severe 12 16 22 24

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 5 — Plumas National Forest
E

195

Table 17b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 15 31 42 46 45 1 16 19 21 24 27

3–6 in 5 5 7 10 12 14 1 8 7 7 8 86–12 in 5 5 8 12 17 21 2 11 12 12 13 14>12 in 0 1 2 4 6 9 0 2 4 6 6 8Litter 4 4 4 4 3 3 2 2 3 3 3 3Duff 16 16 16 17 17 17 11 11 11 11 12 12

Flame length (ft) Moderate 1 3 5 6 6 6 1 4 5 5 5 6

Severe 2 4 7 8 8 8 1 6 6 7 7 8

Torching index Severe 125 13 5 5 13 27 456 5 10 19 28 29Crowning index Severe 14 14 14 14 15 16 18 18 20 20 19 20Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Passive Surface Surface Surface Passive Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 196 301 265 183 182 120 367 52 45 39 34 56

18–29.9 in 1 1 3 4 8 13 3 3 3 3 5 1030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 23 18 14 12 11 11 18 16 15 15 16 18

3–6 in 8 7 6 5 4 4 9 8 7 6 5 56–12 in 5 4 4 4 3 3 6 5 5 5 5 5>12 in 0 1 1 2 2 2 0 1 1 2 3 4Litter 1 1 1 1 1 1 1 1 2 2 2 2Duff 15 15 14 14 14 14 19 19 19 18 18 18

Flame length (ft) Moderate 6 5 4 3 3 3 5 4 4 4 4 4

Severe 8 7 5 5 4 4 6 6 5 5 5 6

Torching index Severe 24 37 53 7 25 66 36 52 70 85 96 100Crowning index Severe 30 34 35 35 35 34 18 21 23 23 22 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 37 29 12 6 5 6 39 32 15 9 14 23

18–29.9 in 1 2 2 2 2 3 1 1 1 2 6 1130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 5 —Plumas National Forest
F

196Table 17b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 6 6 6 6 7 8 4 6 8 10 13 17

3–6 in 2 2 2 2 2 2 3 2 2 2 2 36–12 in 1 2 2 2 2 2 2 2 2 3 3 4>12 in 0 1 1 2 2 2 0 1 1 2 3 4Litter 1 1 1 1 1 1 1 1 2 2 2 2Duff 13 13 13 13 12 12 17 17 17 16 16 16

Flame length (ft) Moderate 2 1 2 2 2 2 1 1 2 2 3 4

Severe 2 2 2 2 3 3 2 2 3 3 4 5

Torching index Severe 218 269 286 38 69 128 410 285 219 172 36 112Crowning index Severe 30 34 35 35 34 34 18 21 22 22 22 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 37 29 13 7 6 6 39 32 16 10 17 24

18–29.9 in 1 2 2 3 2 3 1 1 1 2 6 1030–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 4 4 5 7 0 5 7 8 10 12

3–6 in 2 2 2 2 2 2 3 3 3 3 3 26–12 in 3 3 4 3 3 3 4 5 6 6 6 5>12 in 0 1 2 3 3 3 0 2 4 5 5 5Litter 1 1 1 1 1 1 1 1 1 1 2 2Duff 10 10 10 10 10 10 17 13 13 13 13 13

Flame length (ft) Moderate 6 1 1 2 2 2 5 2 2 2 3 3

Severe 8 1 2 2 2 3 6 2 3 4 4 4

Torching index Severe 24 599 377 43 78 90 36 237 135 20 34 41Crowning index Severe 30 37 39 38 38 37 18 25 26 26 25 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 38 27 19 9 7 7 61 44 26 10 8 14

18–29.9 in 3 3 3 2 2 2 3 3 2 3 2 630–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 5 — Plumas National Forest
G

197

Table 17b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 12 14 19 24 30 34 9 15 23 30 35 38

3–6 in 9 8 7 7 8 10 8 7 7 8 11 146–12 in 6 5 6 9 13 20 5 5 7 10 16 25>12 in 0 1 1 3 6 11 0 1 1 3 6 10Litter 2 3 3 3 3 2 3 3 3 3 3 2Duff 19 19 19 19 19 19 18 18 18 18 18 18

Flame length (ft) Moderate 3 3 4 5 6 6 2 3 4 5 6 6

Severe 5 5 5 6 8 9 3 4 6 7 8 9

Torching index Severe 51 91 108 116 87 69 89 124 137 109 89 81Crowning index Severe 15 17 17 17 19 19 14 15 15 15 17 18Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 40 33 33 43 59 73 46 52 45 57 78 83

18–29.9 in 1 1 2 4 14 15 1 1 2 2 11 1330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 8 15 22 27 31 2 10 20 28 34 37

3–6 in 3 2 3 4 5 7 2 2 3 5 8 116–12 in 2 2 3 6 11 18 2 2 4 8 15 23>12 in 0 1 1 3 6 11 0 1 1 3 6 10Litter 2 3 3 3 3 2 3 3 3 3 3 2Duff 17 17 17 17 17 17 16 16 16 16 16 16

Flame length (ft) Moderate 1 2 3 4 5 6 1 2 4 5 6 6

Severe 1 2 4 6 7 9 1 2 5 7 8 9

Torching index Severe 687 319 157 133 100 66 827 315 154 131 89 79Crowning index Severe 15 17 17 17 19 21 14 15 15 15 18 19Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 40 33 33 41 62 72 46 52 45 59 77 83

18–29.9 in 1 1 2 4 15 16 1 1 2 2 11 1330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 5 —Plumas National Forest
H

198

Table 17c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,427 1,095 840 676 507 427 286 281 261 235 214 176

Quadratic mean diameter (in) 5.9 7.1 8.3 9.5 11.0 12.0 5.9 12.0 13.5 15.2 16.7 18.7Total volume (ft 3) 6,334 8,840 10,724 12,336 13,387 14,296 5,555 6,836 9,303 11,577 13,819 14,896Merchantable volume (ft 3) 4,801 7,090 8,891 10,446 11,641 12,562 4,647 5,822 8,077 10,206 12,348 13,517Basal area (ft 2) 272 301 318 332 334 334 198 220 260 294 327 334Stand density index 614 631 626 621 590 571 347 376 423 458 489 479

Canopy closure (percent) 82 81 80 78 75 73 59 61 64 65 66 63Crown competition factor 169 168 160 151 139 129 89 94 102 105 108 99

Canopy base height (ft) 6 5 9 11 15 23 15 6 10 15 21 25

Canopy bulk density (kg/m3) 0.23 0.22 0.23 0.24 0.22 0.19 0.17 0.17 0.15 0.15 0.15 0.15

Table 17b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 9 12 14 17 21 0 12 15 17 20 24

3–6 in 2 5 5 5 5 5 2 7 6 6 6 76–12 in 3 11 11 11 11 12 3 12 12 12 13 14>12 in 0 2 4 5 6 8 0 2 4 5 6 8Litter 2 2 2 2 2 2 2 2 2 2 2 2Duff 13 13 13 13 13 13 12 12 12 12 12 12

Flame length (ft) Moderate 2 3 4 4 4 5 1 4 4 4 5 5

Severe 2 4 5 5 6 7 1 5 6 6 7 7

Torching index Severe 358 83 76 90 18 99 651 72 80 90 101 96Crowning index Severe 18 20 22 21 21 21 18 19 20 20 20 20Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 79 50 27 18 27 40 97 50 24 27 28 29

18–29.9 in 3 3 2 3 5 12 3 3 2 3 5 730–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Plumas National Forest
I

199

Table 17c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,427 50 98 96 94 92 89 100 122 118 114 108 98

Quadratic mean diameter (in) 5.9 19 15.3 17.3 19.2 21.1 22.7 16.8 17.1 19.2 21.1 23.0 25.0Total volume (ft3) 6,334 3,478 4,246 5,820 7,538 9,409 11,130 5,214 6,381 8,771 11,173 13,284 14,968Merchantable volume (ft3) 4,801 3,151 3,869 5,352 6,961 8,698 10,271 4,637 5,731 8,006 10,280 12,260 13,871Basal area (ft2) 272 98 126 156 188 222 251 155 194 237 279 311 333Stand density index 614 140 196 231 267 303 333 231 288 336 380 410 426Canopy cover (percent) 82 25 28 33 37 41 45 41 45 49 52 55 55Crown competition factor 169 28 33 40 46 53 60 53 60 67 74 79 80Canopy base height (ft) 6 26 29 32 5 10 22 25 29 34 38 42 46Canopy bulk density (kg/m3) 0.23 0.09 0.07 0.07 0.07 0.07 0.07 0.17 0.13 0.12 0.12 0.13 0.12

Pile and burn Trees per acre 1,427 50 124 121 117 114 110 100 135 131 127 118 107

Quadratic mean diameter (in) 5.9 19.0 13.6 15.4 17.2 18.9 20.4 16.8 16.2 18.2 20.1 22.0 23.9Total volume (ft3) 6,334 3,478 4,246 5,818 7,539 9,395 11,109 5,214 6,381 8,776 11,169 13,245 14,944Merchantable volume (ft3) 4,801 3,151 3,869 5,332 6,962 8,684 10,270 4,637 5,731 8,010 10,279 12,238 13,816Basal area (ft2) 272 98 126 156 188 222 250 155 194 237 279 310 333Stand density index 614 140 205 242 279 316 346 231 294 343 388 417 433Canopy cover (percent) 82 25 28 33 37 41 44 41 45 49 52 55 55Crown competition factor 169 28 33 39 46 53 58 53 60 67 74 79 80Canopy base height (ft) 6 26 29 32 5 10 22 25 29 35 38 13 47Canopy bulk density (kg/m3) 0.23 0.09 0.07 0.07 0.07 0.07 0.07 0.17 0.13 0.12 0.12 0.13 0.13

Prescribed fire Trees per acre 1,427 50 192 186 181 176 170 100 144 139 135 131 122

Quadratic mean diameter (in) 5.9 19.0 10.3 11.6 13.1 14.4 15.7 16.8 14.4 16.2 18.0 19.8 21.5Total volume (ft3) 6,334 3,035 3,697 5,064 6,702 8,245 9,970 4,320 5,328 7,373 9,514 11,860 13,711Merchantable volume (ft3) 4,801 2,750 3,371 4,645 6,206 7,582 9,121 3,863 4,825 6,724 8,754 10,955 12,678

Basal area (ft2) 272 98 110 136 168 198 228 155 162 200 238 279 307Stand density index 614 140 200 236 277 314 350 231 257 302 346 391 416Canopy cover (percent) 82 25 25 30 35 40 44 41 38 42 46 50 52Crown competition factor 169 28 29 36 44 51 58 53 47 54 62 70 74Canopy base height (ft) 6 30 34 34 5 10 21 25 29 33 7 12 24Canopy bulk density (kg/m3) 0.23 0.08 0.06 0.06 0.06 0.06 0.06 0.14 0.11 0.10 0.10 0.11 0.11

Region 5 —Plumas National Forest
J

200Table 17c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,427 200 207 190 168 139 106 300 289 258 216 168 121

Quadratic mean diameter (in) 5.9 14.1 15.3 17.1 19.1 21.0 24.0 12.2 13.5 15.1 17.0 19.1 22.5Total volume (ft3) 6,334 6,964 8,531 11,267 13,418 14,416 15,019 7,501 8,952 11,627 13,623 14,244 14,912

Merchantable volume (ft3) 4,801 5,986 7,465 10,034 12,139 13,130 13,845 6,193 7,580 10,162 12,195 12,939 13,738Basal area (ft2) 272 217 266 305 332 333 334 245 286 321 342 333 333Stand density index 614 348 412 452 472 456 433 414 466 500 509 474 444

Canopy cover (percent) 82 63 66 68 67 65 58 71 73 73 70 66 59

Crown competition factor 169 98 109 113 110 106 87 124 129 131 122 109 89Canopy base height (ft) 6 20 32 40 49 51 51 20 36 46 53 56 57Canopy bulk density (kg/m3) 0.23 0.21 0.18 0.18 0.18 0.16 0.15 0.23 0.21 0.20 0.21 0.17 0.16

Pile and burn Trees per acre 1,427 200 214 196 173 141 109 300 296 265 221 172 125

Quadratic mean diameter (in) 5.9 14.1 15.1 16.9 18.8 20.8 23.6 12.2 13.3 14.9 16.8 18.8 22.1Total volume (ft3) 6,334 6,964 8,531 11,262 13,421 14,367 14,974 7,501 8,952 11,617 13,564 14,242 14,920Merchantable volume (ft3) 4,801 5,986 7,465 10,031 12,134 13,089 13,794 6,193 7,580 10,151 12,189 12,932 13,712Basal area (ft2) 272 217 266 305 333 332 332 245 286 320 341 333 334Stand density index 614 348 415 455 476 456 434 414 468 502 509 476 447Canopy cover (percent) 82 63 66 68 67 65 58 71 73 73 70 67 60Crown competition factor 169 98 109 113 111 106 88 124 129 131 121 110 90Canopy base height (ft) 6 20 32 41 49 51 51 20 36 47 54 56 57Canopy bulk density (kg/m3) 0.23 0.21 0.18 0.18 0.18 0.15 0.14 0.23 0.21 0.21 0.21 0.17 0.15

Prescribed fire Trees per acre 1,427 200 169 164 154 139 119 300 199 196 175 159 143

Quadratic mean diameter (in) 5.9 14.1 14.8 16.6 18.5 20.5 22.6 12.2 14.0 15.6 17.6 19.4 21.2Total volume (ft3) 6,334 5,287 6,550 9,142 11,651 13,740 15,029 5,495 6,798 9,516 11,798 13,966 15,857Merchantable volume (ft3) 4,801 4,621 5,800 8,224 10,603 12,603 13,864 4,720 5,943 8,482 10,698 12,762 14,585

Basal area (ft2) 272 217 202 247 289 320 333 245 213 259 294 325 351Stand density index 614 348 318 370 415 442 442 414 342 399 431 459 478Canopy cover (percent) 82 63 51 56 58 59 58 71 56 60 61 62 63Crown competition factor 169 98 72 81 88 90 87 124 82 93 95 98 98Canopy base height (ft) 6 23 31 34 39 13 50 23 32 36 40 47 52Canopy bulk density (kg/m3) 0.23 0.16 0.14 0.13 0.13 0.14 0.13 0.17 0.16 0.14 0.14 0.15 0.15

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Plumas National Forest
K

201

Table 17d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 80 10 20 8 100 0 0

10 10 83 12 17 12 71 10 29

20 12 51 13 49 12 99 10 1

30 13 100 0 0 12 85 13 15

40 13 100 0 0 12 63 13 37

50 13 100 0 0 13 67 12 33

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 12 97 10 3 12 71 10 29

10 12 54 10 46 10 53 12 47

20 10 73 12 27 10 62 12 38

30 10 90 12 10 10 63 12 37

40 10 99 12 1 10 57 12 43

`50 10 99 8 1 12 65 10 35

Pile and burn 1 8 81 10 19 8 91 10 9

10 8 82 10 18 8 73 10 27

20 8 77 10 23 10 53 8 47

30 8 70 10 30 10 78 8 22

40 8 61 10 39 10 93 12 7

50 10 51 8 49 10 59 12 41

Prescribed fire 1 8 100 0 0 8 100 0 0

10 8 100 0 0 8 69 10 31

20 8 86 10 14 10 73 8 27

30 8 76 10 24 10 93 8 7

40 8 67 10 33 10 98 12 2

50 8 51 10 49 10 83 12 17

Region 5 —Plumas National Forest
L

202

Region 5 — Plumas National Forest

Table 17f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 17e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 12 97 3 4 7 15 125 100Moderate—75th percentile 8 72 5 7 10 23 125 150Table 17d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 70 12 30 10 97 12 3

10 10 64 12 36 10 69 12 31

20 12 63 10 37 12 93 10 7

30 12 87 13 13 13 57 12 43

40 13 69 12 31 13 100 0 0

50 13 100 0 0 13 100 0 0

Pile and burn 1 8 100 0 0 8 100 0 0

10 8 56 10 44 10 60 8 40

20 10 89 12 11 12 53 10 47

30 12 77 10 23 12 74 13 26

40 12 60 13 40 13 100 12 0

50 13 100 0 0 13 100 0 0

Prescribed fire 1 8 81 6 19 8 100 0 0

10 10 87 12 13 10 58 12 42

20 10 57 12 43 12 70 10 30

30 12 53 10 47 12 83 10 17

40 12 80 10 20 12 89 13 11

50 12 86 13 14 12 58 13 42

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

203

Site: Elevation = 5,000 ft, slope = 30 percent, aspect = 225°.Species (based on trees per acre): White fir (Abies concolor) = 77 percent, hardwoods = 13 percent, sugar pine (Pinus lambertiana) = 8 percent, ponderosa pine (Pinus ponderosa) = 1 percent.

Stand attributes: Stem density = 776 tpa, basal area = 291 ft2/ac, top height = 119 ft, stand density index = 575, quadratic mean diameter = 8.3 in, crown competition factor = 85, canopy cover = 60 percent. 

Region 5 — Sierra National Forest 1
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

204
C

205

Initial conditions/no-action trajectoryThis stand has 776 trees per acre (tpa) composed primarily of white fir and hardwood understory with ponderosa pine and sugar pine overstory. Canopy bulk density is 0.07 kg/m3 (0.0044 lb/ft3), and canopy base height is 2 ft, so ladder fuels are sufficient to enable passive crown fire, but crown fire spread is unlikely. Woody fuel loading is 18 tons/ac, and litter and duff loading is 16 tons/ac. Potential flame lengths are 5 ft, and potential basal area mortality is 95 percent for severe fire. With no action, canopy base height increases and canopy bulk density decreases rapidly as trees grow. In 30 years, passive crown fire is unlikely for moderate and severe fire weather. Surface fuels also accumulate rapidly, and in 50 years, flame lengths are 8 ft and 12 ft for moderate and severe fire weather respectively. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment raises canopy base height and reduces crown fire potential and flame lengths, but creates many snags that contribute to higher surface fuel loading in 10 years. In the short term, the lower density thinning treatments (50 and 100 tpa) effectively raise canopy base height, reducing crown fire potential, but potential flame lengths are higher than initial conditions because of activity fuels from the treatment. The 200 tpa treatment does not reduce canopy bulk density and only slightly increases canopy base height; the predicted fire type remains passive crown fire, and potential basal area mortality is 95 percent for severe fire weather. The 300 tpa treatment is not sufficient to affect canopy base height or canopy bulk density, so crown fire potential remains similar to initial conditions. The low-density treatments increase surface fuels slightly, but flame lengths remain similar to initial conditions, and the higher density treatments have little effect on surface fuels. The pile and burn treatment and, to a greater extent the prescribed fire treatment, reduce surface fuels and flame lengths to below initial conditions. The prescribed fire treatment reduces crown fire potential more than thinning alone because fire-caused mortality of small trees further increase canopy base height. 

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, crown fire potential increases slightly over time as surface fuels accumulate, but the predicted fire type is surface fire for 50 years, and potential flame lengths remain lower than the no-action trajectory. Surface fuels accumulate rapidly in the low-density treatments without surface fuel treatment, and flame lengths exceed 10 ft in 20 years, but canopy base height also increases as the trees grow and the stand continues to self-thin. Canopy base height remains high in relation to flame lengths in the 50 tpa treatment with a pile and burn, and in the 100 tpa treatment with no surface fuel treatment and pile and burn. The predicted fire type is surface fire for the 50-year projection. In the 50 tpa treatment without surface fuel treatment, the combination of regeneration and high activity fuels creates conditions conducive to passive crown fire in 20 years. Regeneration causes a decrease in canopy base height in the 50 tpa and 100 tpa treatments with prescribed fire in 20 years, and passive crown fire is the predicted fire type for severe and moderate fire weather. In the higher density treatments, canopy base height increases in 10 years and the predicted fire type becomes surface fire and remains surface fire for the 50-year projection.

Region 5 — Sierra National Forest 1
D

206Table 18a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 6 4 3 3

3–6 in 7 1 6 7 7 76–12 in 8 4 7 7 8 8>12 in 0 0 0 0 0 0Litter 1 1 1 1 1 1Duff 15 10 13 14 14 15

Flame length (ft) Moderate 3 1 3 2 3 3

Severe 5 2 4 4 5 5

Torching index Severe 0 557 137 203 0 0Crowning index Severe 30 38 36 30 30 30Type of fire Moderate Passive Surface Surface Surface Surface Passive

Severe Passive Surface Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 31 9 8 11 13 31

Severe 95 9 8 12 94 95

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 1 1 1

3–6 in 2 2 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 1Duff 12 13 13 13

Flame length (ft) Moderate 1 1 3 3

Severe 1 1 5 5

Torching index Severe 736 761 0 0Crowning index Severe 36 30 30 30Type of fire Moderate Surface Surface Surface Passive

Severe Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 8 11 13 31

Severe 8 11 94 95

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 4 4 4 4>12 in 0 0 0 0Litter 1 1 1 1Duff 9 10 10 10

Flame length (ft) Moderate 1 1 1 1

Severe 2 1 1 2

Torching index Severe 686 752 753 563Crowning index Severe 39 34 34 38Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 7 9 9 9

Severe 7 9 9 9

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 5 — Sierra National Forest 1
E

207

Table 18b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 9 19 25 27 28 1 8 10 11 14 15

3–6 in 7 7 8 8 7 8 1 3 3 3 3 36–12 in 8 9 11 12 13 13 4 7 9 8 8 9>12 in 0 4 10 18 25 33 0 6 14 17 21 28Litter 1 2 2 2 1 1 1 1 1 1 1 1Duff 15 15 15 15 15 15 10 10 10 10 10 10

Flame length (ft) Moderate 3 4 6 8 8 8 1 3 5 5 6 7

Severe 5 5 9 11 11 12 2 5 7 8 9 10

Torching index Severe 0 0 0 13 24 37 557 134 109 124 142 129Crowning index Severe 30 19 19 23 29 46 38 41 40 43 48 53Type of fire Moderate Passive Passive Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 185 221 230 209 172 140 245 58 32 30 40 38

18–29.9 in 21 25 32 32 34 33 30 27 22 24 31 3130–36 in 7 8 10 13 15 15 11 10 9 10 12 14

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 6 8 10 13 17 18 4 8 13 16 19 20

3–6 in 6 6 6 5 6 6 7 7 7 7 7 76–12 in 7 7 7 7 8 8 7 8 9 11 12 12>12 in 0 3 6 10 15 23 0 3 9 16 24 32Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 13 13 13 13 12 12 14 14 14 14 13 13

Flame length (ft) Moderate 3 3 4 5 6 7 2 3 5 7 8 8

Severe 4 5 6 7 9 10 4 5 8 9 11 11

Torching index Severe 137 146 0 122 129 134 203 130 97 92 80 85Crowning index Severe 36 37 40 45 49 59 30 34 39 45 47 51Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 61 44 33 40 45 39 68 67 60 57 54 46

18–29.9 in 14 14 19 27 26 33 16 21 29 33 34 3530–36 in 6 6 8 10 12 17 6 7 10 12 15 16

Region 5 — Sierra National Forest 1
F

208Table 18b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 5 9 13 16 19 1 6 12 17 18 19

3–6 in 2 2 3 3 4 4 2 3 4 5 5 56–12 in 2 3 4 4 5 6 2 3 6 8 9 10>12 in 0 2 6 10 14 22 0 3 9 16 24 32Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 12 12 11 11 11 11 13 12 12 12 12 12

Flame length (ft) Moderate 1 2 3 5 6 7 1 2 4 6 7 8

Severe 1 3 5 7 8 10 1 3 6 9 10 11

Torching index Severe 736 508 205 132 161 145 761 375 109 105 93 93Crowning index Severe 36 35 38 40 50 53 30 34 38 41 43 47Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 61 44 35 38 45 40 68 67 58 56 46 54

18–29.9 in 14 14 19 22 35 31 16 21 28 32 34 3430–36 in 6 6 7 10 14 15 6 7 10 13 15 17

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 5 8 12 15 17 0 6 10 15 17 19

3–6 in 2 3 3 3 3 3 2 3 3 5 5 56–12 in 4 5 6 6 5 6 4 7 8 9 9 10>12 in 0 4 9 12 15 19 0 4 10 15 22 28Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 9 9 9 9 9 9 13 10 10 10 10 10

Flame length (ft) Moderate 1 2 4 5 6 6 1 3 4 6 7 7

Severe 2 3 5 7 8 9 1 4 6 8 10 10

Torching index Severe 686 332 0 31 50 151 752 210 0 6 21 26Crowning index Severe 39 38 40 40 44 44 34 33 37 40 45 48Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 57 40 36 36 46 57 69 47 57 61 51 53

18–29.9 in 22 20 20 17 23 29 22 20 25 24 33 3030–36 in 8 7 8 8 11 15 8 7 9 12 14 14

Region 5 — Sierra National Forest 1
G

209

Table 18b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 8 15 19 23 23 3 8 15 21 22 25

3–6 in 7 7 7 7 8 8 7 7 7 7 7 86–12 in 8 8 10 11 12 13 8 8 10 12 13 13>12 in 0 3 9 16 24 34 0 3 10 17 24 32Litter 1 2 1 1 1 1 1 2 1 1 1 1Duff 14 14 14 14 14 14 15 14 14 14 14 14

Flame length (ft) Moderate 3 3 6 7 8 8 3 3 6 7 8 8

Severe 5 5 8 10 11 12 5 5 8 10 11 12

Torching index Severe 0 20 22 73 68 69 0 12 18 21 58 58Crowning index Severe 30 32 36 45 49 51 30 32 37 39 46 48Type of fire Moderate Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 80 94 95 89 64 49 87 136 115 84 90 63

18–29.9 in 18 23 28 33 36 37 18 23 31 32 34 3530–36 in 7 7 10 13 16 17 7 7 9 11 14 17

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 6 14 18 21 23 1 6 14 20 22 24

3–6 in 2 3 4 4 5 5 2 3 4 4 5 66–12 in 2 4 6 9 10 11 2 4 6 9 10 11>12 in 0 3 9 16 24 33 0 3 9 17 24 32Litter 1 2 1 1 1 1 1 2 1 1 1 1Duff 13 13 13 13 13 13 13 13 13 13 13 13

Flame length (ft) Moderate 3 2 5 7 8 8 3 2 5 7 8 8

Severe 5 3 7 9 11 12 5 3 7 10 11 12

Torching index Severe 0 68 29 78 78 76 0 50 25 25 60 46Crowning index Severe 30 32 36 43 52 56 30 32 37 40 46 51Type of fire Moderate Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 80 94 81 90 76 52 87 136 117 82 90 64

18–29.9 in 18 23 29 32 38 37 18 23 31 32 34 3530–36 in 7 7 10 12 14 15 7 7 9 11 14 17

Region 5 — Sierra National Forest 1
H

210

Table 18c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 776 565 406 270 183 97 62 61 60 53 43 37

Quadratic mean diameter (in) 8.3 10.0 11.8 14.5 17.6 24.1 8.3 27.9 30.2 32.8 36.3 39.0Total volume (ft 3) 11,693 13,764 15,053 16,298 17,045 17,531 10,817 12,422 15,718 17,678 18,358 18,765

Merchantable volume (ft 3) 10,745 12,648 13,828 15,001 15,682 16,317 10,055 11,577 14,711 16,582 17,293 17,668Basal area (ft 2) 291 310 309 310 308 306 241 261 300 314 308 308Stand density index 575 568 530 491 453 397 300 319 355 360 339 330

Canopy closure (percent) 60 66 65 63 61 58 47 49 54 56 55 55Crown competition factor 85 116 102 89 79 68 55 58 64 65 61 60Canopy base height (ft) 2 3 10 21 31 40 31 45 52 59 69 74Canopy bulk density (kg/m3) 0.07 0.13 0.13 0.11 0.08 0.04 0.06 0.05 0.05 0.05 0.04 0.03

Table 18b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 6 10 15 17 18 0 7 9 11 15 16

3–6 in 2 3 4 5 5 5 2 4 4 4 5 56–12 in 4 7 8 9 10 10 4 8 9 9 9 9>12 in 0 4 10 15 23 30 0 6 14 18 22 28Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 1 3 4 6 7 7 1 3 5 6 6 7

Severe 1 4 7 9 10 11 2 5 7 8 9 10

Torching index Severe 753 181 108 106 98 93 563 119 99 113 118 113Crowning index Severe 34 35 39 43 46 50 38 39 41 44 46 49Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 95 49 52 50 44 53 128 58 41 40 50 39

18–29.9 in 22 21 25 30 33 33 30 27 24 26 28 3130–36 in 8 8 9 13 15 18 11 10 10 11 14 16

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 1
I

211

Table 18c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 776 53 102 88 72 53 43 100 109 87 70 54 45

Quadratic mean diameter (in) 8.3 29.4 22.7 25.3 27.9 33.2 36.0 22.9 22.7 25.4 28.4 32.3 35.2Total volume (ft3) 11,693 12,340 13,972 16,223 17,199 18,698 18,764 13,266 14,299 15,947 16,843 17,662 18,539Merchantable volume (ft3) 10,745 11,500 13,044 15,203 16,141 17,582 17,660 12,289 13,300 14,919 15,803 16,588 17,445Basal area (ft2) 291 250 288 305 306 318 307 286 306 306 306 306 308Stand density index 575 299 381 388 373 363 339 378 406 389 372 353 343Canopy cover (percent) 60 48 52 55 55 56 55 54 55 55 55 54 54Crown competition factor 85 54 60 65 63 63 59 70 70 68 65 62 60Canopy base height (ft) 2 31 46 4 58 65 77 29 41 49 54 60 69Canopy bulk density (kg/m3) 0.07 0.06 0.06 0.05 0.04 0.04 0.03 0.07 0.06 0.05 0.04 0.04 0.04

Pile and burn Trees per acre 776 53 128 108 92 74 63 100 122 98 77 68 46

Quadratic mean diameter (in) 8.3 29.4 20.3 22.8 25.2 27.5 30.4 22.9 21.5 23.9 27.1 29.1 35.1Total volume (ft3) 11,693 12,340 13,972 16,235 17,732 18,057 19,310 13,266 14,299 15,858 17,141 18,127 18,425Merchantable volume (ft3) 10,745 11,500 13,044 15,209 16,630 16,949 18,140 12,289 13,300 14,835 16,068 17,027 17,321Basal area (ft2) 291 250 288 306 317 303 316 286 306 306 309 311 308Stand density index 575 299 399 405 403 373 374 378 415 398 382 375 344Canopy cover (percent) 60 48 52 56 57 57 57 54 55 55 55 55 54Crown competition factor 85 54 60 68 68 64 64 70 70 69 66 64 60Canopy base height (ft) 2 31 44 52 57 73 77 29 41 48 56 62 69Canopy bulk density (kg/m3) 0.07 0.06 0.06 0.06 0.05 0.04 0.03 0.07 0.06 0.06 0.05 0.05 0.04

Prescribed fire Trees per acre 776 53 197 173 153 128 101 100 140 120 85 74 56

Quadratic mean diameter (in) 8.3 29.4 15.8 17.6 19.7 21.4 23.6 22.9 19.3 21.7 25.5 27.4 32.3Total volume (ft3) 11,693 11,540 13,078 15,451 18,082 18,719 18,263 12,307 13,572 15,968 16,917 17,686 18,992Merchantable volume (ft3) 10,745 10,762 12,222 14,458 16,906 17,509 17,093 11,427 12,645 14,929 15,864 16,603 17,863Basal area (ft2) 291 250 266 292 323 318 305 286 285 306 303 304 318Stand density index 575 299 408 429 453 433 398 378 403 414 383 375 367Canopy cover (percent) 60 48 50 57 60 59 57 54 54 56 57 56 57Crown competition factor 85 54 56 73 77 72 66 70 66 71 66 64 64Canopy base height (ft) 2 32 45 4 17 29 69 31 42 4 11 23 73Canopy bulk density (kg/m3) 0.07 0.05 0.05 0.05 0.05 0.05 0.04 0.06 0.07 0.06 0.05 0.04 0.04

Region 5 — Sierra National Forest 1
J

212Table 18c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 776 200 169 120 75 60 51 300 222 168 129 80 65

Quadratic mean diameter (in) 8.3 16.3 18.3 21.7 27.4 30.4 33.0 13.3 15.9 18.2 20.9 26.5 29.2Total volume (ft3) 11,693 13,148 14,097 15,666 16,492 17,063 17,911 13,177 13,976 15,481 16,818 17,244 17,670Merchantable volume (ft3) 10,745 12,121 13,030 14,578 15,431 15,995 16,813 12,131 12,912 14,353 15,626 16,130 16,544Basal area (ft2) 291 291 306 306 306 302 303 291 307 305 307 304 302Stand density index 575 439 443 414 377 356 347 476 469 440 421 380 363Canopy cover (percent) 60 57 57 56 55 55 55 57 59 58 57 56 55

Crown competition factor 85 80 78 72 66 63 61 85 83 77 72 66 63Canopy base height (ft) 2 4 9 18 50 58 64 2 7 16 25 51 57Canopy bulk density (kg/m3) 0.07 0.07 0.07 0.06 0.04 0.04 0.03 0.07 0.07 0.06 0.05 0.04 0.04

Pile and burn Trees per acre 776 200 173 137 85 61 53 300 229 172 136 84 68

Quadratic mean diameter (in) 8.3 16.3 18.0 20.2 25.7 30.1 32.2 13.3 15.7 18.1 20.3 25.8 28.5

Total volume (ft3) 11,693 13,148 14,097 15,709 16,668 17,082 17,855 13,177 13,976 15,501 16,798 17,260 17,693Merchantable volume (ft3) 10,745 12,121 13,030 14,596 15,599 16,019 16,781 12,131 12,912 14,372 15,597 16,138 16,547Basal area (ft2) 291 291 306 307 306 299 300 291 307 305 307 305 302Stand density index 575 439 445 426 387 354 347 476 471 443 425 384 367Canopy cover (percent) 60 57 57 57 56 55 55 57 59 58 57 56 55

Crown competition factor 85 80 78 74 67 62 61 85 83 78 73 66 63

Canopy base height (ft) 2 4 9 18 48 59 65 2 7 16 25 50 47Canopy bulk density (kg/m3) 0.07 0.07 0.07 0.06 0.05 0.04 0.03 0.07 0.07 0.06 0.05 0.04 0.04

Prescribed fire Trees per acre 776 200 120 99 79 68 46 300 102 95 81 57 51

Quadratic mean diameter (in) 8.3 16.3 21.1 23.8 26.7 28.9 35.0 13.3 21.7 23.8 26.3 31.4 33.4Total volume (ft3) 11,693 12,247 13,896 15,967 17,243 18,144 18,357 10,829 12,460 15,264 17,155 18,167 18,931Merchantable volume (ft3) 10,745 11,362 12,921 14,937 16,183 17,034 17,262 10,066 11,612 14,283 16,083 17,065 17,812Basal area (ft2) 291 291 294 306 309 311 308 291 261 291 306 309 311Stand density index 575 439 401 398 384 375 344 476 353 379 383 360 354Canopy cover (percent) 60 57 54 55 55 55 54 57 50 54 55 55 55

Crown competition factor 85 80 67 69 67 64 61 85 58 65 66 63 62Canopy base height (ft) 2 31 40 48 55 61 66 31 42 49 56 63 71Canopy bulk density (kg/m3) 0.07 0.06 0.06 0.05 0.05 0.04 0.04 0.06 0.05 0.05 0.05 0.04 0.04

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 1
K

213

Table 18d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 100 0 0 8 93 5 7

10 10 83 12 17 10 99 12 1

20 12 91 13 9 10 55 12 45

30 13 71 12 29 12 61 10 39

40 13 100 0 0 12 94 10 6

50 13 100 0 0 12 74 13 26

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 67 8 33 8 55 10 45

10 10 100 0 10 98 12 2

20 10 77 12 23 12 62 10 38

30 12 55 10 45 12 89 13 11

40 12 98 13 2 13 56 12 44

`50 12 71 13 29 13 86 12 14

Pile and burn 1 8 100 0 0 8 100 0 0

10 8 78 10 22 8 66 10 34

20 10 88 8 12 10 69 12 31

30 10 61 12 39 12 97 10 3

40 12 75 10 25 12 62 13 38

50 12 76 13 24 13 64 12 36

Prescribed fire 1 8 98 5 2 8 100 0 0

10 8 60 10 40 10 67 8 33

20 10 91 12 9 10 70 12 30

30 10 59 12 41 12 87 10 13

40 12 73 10 27 12 74 13 26

50 12 97 13 3 13 56 12 44

Region 5 — Sierra National Forest 1
L

214

Region 5 — Sierra National Forest 1

Table 18f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 18e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 17 83 2 5 10 15 50 100Moderate—75th percentile 11 72 5 7 15 17 125 150Table 18d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 100 0 0 10 100 0 0

10 10 95 12 5 10 94 12 6

20 12 78 10 22 12 80 10 20

30 12 70 13 30 12 55 13 45

40 13 79 12 21 13 78 12 22

50 13 100 0 0 13 100 0 0

Pile and burn 1 10 100 0 0 10 100 0 0

10 8 60 10 40 8 58 10 42

20 10 53 12 47 10 51 12 49

30 12 89 13 11 12 76 13 24

40 13 56 12 44 13 63 12 37

50 13 96 12 4 13 100 0 0

Prescribed fire 1 8 100 0 0 8 94 5 6

10 10 73 8 27 10 97 12 3

20 10 67 12 33 10 51 12 49

30 12 88 10 12 12 69 10 31

40 12 72 13 28 12 94 13 6

50 13 54 12 46 12 61 13 39

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

215

Region 5 — Sierra National Forest 2

Site: Elevation = 4,500 ft, slope = 40 percent, aspect = 360°.Species (based on trees per acre): Hardwoods = 77 percent, sugar pine (Pinus lambertiana) = 13 percent, white fir (Abies concolor) = 4 percent, ponderosa pine (Pinus ponderosa) = 4 percent.

Stand attributes: Stem density = 1,817 tpa, basal area = 289 ft2/ac, top height = 112 ft, stand density index = 676, quadratic mean diameter = 5.4 in, crown competition factor = 136, canopy cover = 69 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

216

Region 5 — Sierra National Forest 2
C

217

Initial conditions/no-action trajectoryThis stand has 1,817 trees per acre (tpa) composed primarily of white fir and hardwood understory with ponderosa pine and sugar pine overstory. Canopy bulk density is 0.05 kg/m3 (0.0031 lb/ft3), and canopy base height is 6 ft, so ladder fuels and canopy fuels are not sufficient to enable crown fire under moderate or severe fire weather. Woody fuel loading is 18 tons/ac, and litter and duff loading is 16 tons/ac. Potential flame lengths are 3 ft, and potential basal area mortality is 15 percent for severe fire. With no action, canopy base height decreases and canopy bulk density increases in 10 years as smaller trees grow into the overstory, and passive crown fire is predicted for moderate and severe fire weather. In 20 years, canopy base height increases again, but surface fuels also increase potential flame lengths, so passive crown fire remains likely for severe fire weather, and surface fire is predicted for moderate fire weather. Surface fuels continue to accumulate contributing to higher potential flame lengths; in 50 years flame lengths are 9 ft and 12 ft for moderate and severe fire weather, respectively.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment reduces crown fire potential, flame lengths, and basal area mortality, but creates many snags that contribute to higher surface fuel loadings and potential flame lengths in 10 years. In the short term, all thinning treatments increase canopy base height and reduce crown fire potential and basal area mortality; the greater the thinning, the greater is the reduction in crown fire potential and basal area mortality. However, if no surface fuel treatment is applied, activity fuels increase potential flame lengths in all treatments. Both the pile and burn and prescribed fire treatments reduce surface fuel loading in all size classes, decreasing potential flame lengths and basal area mortality to below initial conditions. Canopy bulk density is low enough under initial conditions that none of the treatments are sufficient to reduce canopy bulk density, but active crown fire is unlikely, so reductions in canopy bulk density are not necessary in this stand.

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, crown fire potential increases slightly over time as surface fuels accumulate, but predicted fire type remains surface fire for 50 years, and potential flame lengths remain low. Surface fuels accumulate rapidly in the low-density treatments with no surface fuel treatment, and flame lengths exceed 10 ft in 20 years, but canopy base height also increases as the trees grow and the stand self-thins. Canopy base height remains high relative to flame lengths in the 50 tpa treatment with a pile and burn, and in the 100 tpa treatment with no surface fuel treatment and pile and burn, so predicted fire type is surface fire for 50 years. In the 50 tpa treatment without surface fuel treatment the combination of regeneration and high activity fuels creates conditions conducive to passive crown fire in 20 years. Regeneration causes a decrease in canopy base height in the 50 tpa and 100 tpa treatments with prescribed fire in 20 years, and passive crown fire is the predicted fire type for severe and moderate fire weather. In the higher density treatments, canopy base height continues to increase, and the predicted fire type remains surface fire for the 50-year projection.

Region 5 — Sierra National Forest 2
D

218Table 19a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 5 5 4 4

3–6 in 7 1 7 7 7 76–12 in 8 4 7 7 8 8>12 in 0 0 0 0 0 0Litter 1 1 1 1 1 1Duff 15 10 13 14 15 15

Flame length (ft) Moderate 2 1 3 3 3 3

Severe 3 1 5 4 4 4

Torching index Severe 50 994 205 144 128 75Crowning index Severe 43 46 43 43 43 43Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 15 9 8 10 12 13

Severe 15 9 8 11 13 14

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 2 2 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 1Duff 12 13 13 13

Flame length (ft) Moderate 1 1 1 1

Severe 1 1 1 1

Torching index Severe 1,060 697 522 315Crowning index Severe 43 43 43 43Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 8 10 12 13

Severe 8 10 12 13

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 4 4 4 5>12 in 0 0 0 0Litter 1 1 1 1Duff 9 10 10 10

Flame length (ft) Moderate 1 1 1 1

Severe 1 1 1 1

Torching index Severe 1,015 1,046 972 983Crowning index Severe 46 46 46 46Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 7 8 9 9

Severe 7 8 9 9

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 5 — Sierra National Forest 2
E

219

Table 19b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 7 15 20 23 25 1 6 7 8 11 13

3–6 in 7 7 8 8 10 12 1 3 3 3 3 36–12 in 8 8 9 10 11 12 4 5 6 5 5 5>12 in 0 3 10 16 22 28 0 4 10 12 13 16

Litter 1 1 1 2 2 2 1 1 1 1 1 1

Duff 15 15 15 15 14 15 10 10 10 10 10 10

Flame length (ft) Moderate 2 3 6 7 8 9 1 3 4 4 5 6

Severe 3 5 8 10 11 12 1 4 5 6 7 8

Torching index Severe 50 0 1 1 6 15 994 270 146 74 75 82

Crowning index Severe 43 34 27 25 25 26 46 42 39 41 41 42Type of fire Moderate Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 246 472 403 289 259 213 475 42 27 26 27 28

18–29.9 in 29 32 31 28 27 25 32 29 21 17 15 1330–36 in 8 9 11 12 13 14 9 8 7 7 7 7

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 5 7 8 9 10 11 5 6 8 9 12 15

3–6 in 7 7 6 5 5 4 7 7 6 6 5 56–12 in 7 7 6 5 5 4 7 7 7 6 6 7>12 in 0 3 7 8 9 10 0 3 6 8 10 14

Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 13 13 13 13 12 12 14 14 14 13 13 13

Flame length (ft) Moderate 3 3 4 4 4 5 3 3 4 4 5 6

Severe 5 5 6 6 6 7 4 5 6 6 7 9

Torching index Severe 205 170 0 15 47 69 144 122 98 106 112 117

Crowning index Severe 43 40 38 40 42 45 43 38 36 39 40 44

Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 40 34 24 17 14 15 41 35 25 26 34 41

18–29.9 in 26 23 19 14 12 12 26 23 18 16 16 1930–36 in 7 7 6 6 6 6 7 7 6 6 7 8

Region 5 — Sierra National Forest 2
F

220Table 19b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 4 6 8 10 12 1 4 6 9 12 15

3–6 in 2 2 2 2 2 3 2 2 2 3 3 36–12 in 2 3 3 3 2 3 2 3 3 3 4 5>12 in 0 3 6 8 9 11 0 3 6 8 11 14Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 12 12 11 11 11 11 13 12 12 12 12 12

Flame length (ft) Moderate 1 2 3 3 4 5 1 2 3 3 5 6

Severe 1 2 4 5 6 7 1 3 5 5 7 8

Torching index Severe 1,060 734 25 244 206 187 697 499 120 25 124 121

Crowning index Severe 43 38 36 37 39 41 43 37 35 37 39 41Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 40 34 24 18 19 18 41 35 28 28 34 37

18–29.9 in 26 23 19 14 12 12 26 23 19 16 16 19

30–36 in 7 7 6 6 6 6 7 7 6 6 7 10

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 4 6 8 10 11 0 4 6 8 10 11

3–6 in 2 3 2 2 3 3 2 3 3 3 3 36–12 in 4 5 5 5 4 4 4 6 6 5 5 4>12 in 0 4 10 12 13 15 0 4 10 11 13 14Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 9 9 9 9 9 9 13 10 9 9 9 9

Flame length (ft) Moderate 1 2 3 4 5 5 1 3 4 4 5 5

Severe 1 3 5 6 7 7 1 4 5 6 7 7

Torching index Severe 1,015 432 0 39 66 71 1,046 325 0 17 42 50Crowning index Severe 46 42 40 42 44 45 46 41 39 40 40 40Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 49 41 28 28 26 22 58 41 28 19 21 20

18–29.9 in 32 28 22 17 14 12 32 28 22 15 13 1230–36 in 9 8 7 7 7 6 9 8 8 7 6 6

Region 5 — Sierra National Forest 2
G

221

Table 19b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 6 9 11 14 19 4 6 9 12 17 20

3–6 in 7 6 6 6 6 8 7 7 6 6 7 76–12 in 8 7 7 7 7 9 8 8 8 7 9 11>12 in 0 3 7 9 13 18 0 3 7 10 14 20Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 15 14 14 14 14 14 15 15 15 14 14 14

Flame length (ft) Moderate 3 3 4 5 6 7 3 3 5 5 7 8

Severe 4 5 6 7 8 10 4 5 6 7 9 11

Torching index Severe 128 113 82 86 78 57 75 66 43 51 45 40Crowning index Severe 43 38 36 38 37 37 43 39 37 41 40 40Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 44 46 41 37 54 53 49 55 53 68 71 68

18–29.9 in 26 24 21 17 19 17 26 25 22 20 22 2430–36 in 7 7 7 7 9 9 7 7 7 8 10 12

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 4 7 10 14 19 1 4 8 11 17 22

3–6 in 2 2 3 3 4 6 2 2 3 3 5 66–12 in 2 3 3 4 5 7 2 3 4 4 6 9>12 in 0 3 7 9 13 18 0 3 7 10 14 21Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 13 13 13 13 12 12 13 13 13 13 13 13

Flame length (ft) Moderate 1 2 3 4 6 7 1 2 3 5 6 8

Severe 1 3 5 6 8 10 1 3 5 6 9 11

Torching index Severe 522 423 115 107 83 73 315 256 69 64 50 47Crowning index Severe 43 38 36 38 37 39 43 39 37 41 41 43Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 44 46 41 37 55 51 49 55 53 69 77 69

18–29.9 in 26 24 21 17 19 21 26 25 22 20 24 2330–36 in 7 7 7 7 9 11 7 7 7 8 10 11

Region 5 — Sierra National Forest 2
H

222

Table 19c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,817 1,306 948 694 461 312 144 143 142 132 122 109

Quadratic mean diameter (in) 5.4 6.7 8.2 9.9 12.1 14.7 5.4 18.8 20.0 21.6 23.3 25.5Total volume (ft 3) 12,433 13,449 14,479 15,479 16,141 16,941 12,295 13,297 15,474 17,365 19,276 21,105Merchantable volume (ft 3) 11,325 12,047 12,729 13,468 14,311 15,437 11,386 12,275 14,265 16,081 17,979 19,720

Basal area (ft 2) 289 322 349 370 369 367 260 276 310 337 364 387Stand density index 676 690 692 682 627 578 377 394 432 456 477 490Canopy closure (percent) 69 79 80 79 75 71 52 55 59 61 63 65Crown competition factor 136 218 193 170 140 119 66 70 77 81 85 87Canopy base height (ft) 6 3 10 15 20 26 40 44 45 28 32 38Canopy bulk density (kg/m3) 0.05 0.06 0.08 0.09 0.09 0.09 0.04 0.05 0.05 0.05 0.05 0.05

Table 19b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 5 7 8 10 12 0 5 7 8 11 13

3–6 in 2 3 3 3 3 3 2 4 3 3 3 46–12 in 4 6 6 5 5 5 5 6 6 5 5 5>12 in 0 4 10 11 12 14 0 4 10 11 13 15Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 1 3 4 4 5 5 1 3 4 4 5 6

Severe 1 4 6 6 7 7 1 4 6 6 7 8

Torching index Severe 972 275 145 17 51 68 983 263 141 19 53 64Crowning index Severe 46 42 39 40 41 41 46 41 39 41 41 42Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 76 41 27 22 23 25 97 41 28 27 26 34

18–29.9 in 32 28 21 15 14 14 32 28 21 16 14 1630–36 in 9 8 7 7 7 7 9 8 7 7 7 8

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 2
I

223

Table 19c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,817 50 99 98 96 94 89 100 124 121 112 99 84

Quadratic mean diameter (in) 5.4 30.7 22.8 24.0 25.2 26.2 27.5 22.3 21.2 22.5 24.1 26.2 28.4Total volume (ft3) 12,433 12,951 13,971 15,870 17,932 19,697 21,222 13,284 14,407 16,682 18,510 19,887 20,831Merchantable volume (ft3) 11,325 12,098 13,054 14,848 16,801 18,458 19,910 12,330 13,356 15,517 17,253 18,591 19,549Basal area (ft2) 289 256 282 306 332 352 368 270 302 335 357 369 369Stand density index 676 302 373 397 423 441 453 361 412 445 461 462 448Canopy cover (percent) 69 48 52 55 58 60 62 53 57 61 62 63 62Crown competition factor 136 54 58 66 70 74 76 64 70 78 80 80 77

Canopy base height (ft) 6 44 48 4 10 21 30 27 33 34 40 47 54

Canopy bulk density (kg/m3) 0.05 0.05 0.05 0.05 0.05 0.05 0.04 0.05 0.05 0.06 0.05 0.05 0.04

Pile and burn Trees per acre 1,817 50 125 124 121 114 108 1,644 137 132 122 109 95

Quadratic mean diameter (in) 5.4 30.7 20.3 21.3 22.5 23.8 25.0 5.0 20.1 21.5 23.1 24.9 26.6Total volume (ft3) 12,433 12,951 13,971 15,881 17,953 19,602 21,133 13,284 14,407 16,492 18,421 19,935 20,611Merchantable volume (ft3) 11,325 12,098 13,054 14,849 16,788 18,335 19,749 12,330 13,356 15,341 17,161 18,635 19,296Basal area (ft2) 289 256 282 307 334 352 368 361 302 331 355 369 368Stand density index 676 302 391 418 444 458 470 64 421 449 468 472 459

Canopy cover (percent) 69 48 52 57 60 62 63 53 57 60 62 63 62Crown competition factor 136 54 58 70 75 77 80 112 70 78 81 81 79Canopy base height (ft) 6 44 48 6 56 63 67 27 33 34 10 47 54Canopy bulk density (kg/m3) 0.05 0.05 0.05 0.06 0.06 0.05 0.05 0.05 0.05 0.06 0.05 0.05 0.05

Prescribed fire Trees per acre 1,817 50 193 190 180 170 161 100 136 133 131 124 117

Quadratic mean diameter (in) 5.4 30.7 15.7 16.7 17.8 18.8 20.0 22.3 19.0 20.1 21.3 22.6 23.9Total volume (ft3) 12,433 12,143 13,092 14,924 16,552 18,099 19,849 12,293 13,296 15,187 17,238 18,969 20,637Merchantable volume (ft3) 11,325 11,354 12,259 13,943 15,439 16,833 18,397 11,466 12,398 14,198 16,106 17,724 19,334

Basal area (ft2) 289 256 260 289 309 327 350 270 269 295 323 344 363Stand density index 676 302 399 432 451 467 488 361 382 410 440 457 472Canopy cover (percent) 69 48 49 57 60 62 64 53 51 56 59 61 63Crown competition factor 136 54 53 74 77 80 84 64 58 68 73 76 79Canopy base height (ft) 6 44 49 4 16 28 36 44 47 4 10 20 29

Canopy bulk density (kg/m3) 0.05 0.04 0.05 0.05 0.05 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05

Region 5 — Sierra National Forest 2
J

224Table 19c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,817 200 201 186 170 135 107 300 291 263 220 179 141

Quadratic mean diameter (in) 5.4 16.0 16.9 18.4 20.0 22.4 25.5 13.2 14.1 15.6 17.5 19.4 21.9Total volume (ft3) 12,433 13,403 14,425 16,514 18,522 19,163 20,311 13,443 14,361 16,343 17,952 18,696 19,217Merchantable volume (ft3) 11,325 12,284 13,156 15,168 17,066 17,836 18,973 12,260 13,014 14,815 16,464 17,284 17,880Basal area (ft2) 289 280 312 343 369 369 379 284 317 349 369 369 369Stand density index 676 426 465 494 515 492 481 467 507 537 541 520 496

Canopy cover (percent) 69 57 60 63 65 64 63 60 64 66 67 66 64Crown competition factor 136 78 83 89 92 87 85 91 97 102 101 94 88Canopy base height (ft) 6 19 28 31 36 39 44 11 17 19 25 30 39Canopy bulk density (kg/m3) 0.05 0.05 0.05 0.06 0.05 0.06 0.06 0.05 0.05 0.06 0.05 0.05 0.05

Pile and burn Trees per acre 1,817 200 206 189 173 137 116 300 298 270 226 181 148

Quadratic mean diameter (in) 5.4 16.0 16.7 18.2 19.8 22.2 24.2 13.2 14.0 15.4 17.3 19.3 21.3

Total volume (ft3) 12,433 13,403 14,425 16,504 18,506 19,144 19,707 13,443 14,361 16,357 17,926 18,744 19,660Merchantable volume (ft3) 11,325 12,284 13,156 15,159 17,049 17,820 18,379 12,260 13,014 14,826 16,437 17,332 18,286Basal area (ft2) 289 280 312 343 369 369 368 284 317 350 369 369 369Stand density index 676 426 467 496 517 494 477 467 509 540 545 521 501Canopy cover (percent) 69 57 60 63 65 64 63 60 64 66 67 66 65Crown competition factor 136 78 83 89 92 87 84 91 97 103 102 96 90Canopy base height (ft) 6 19 28 31 36 38 45 11 17 19 25 29 39Canopy bulk density (kg/m3) 0.05 0.05 0.05 0.06 0.05 0.06 0.05 0.05 0.05 0.06 0.05 0.05 0.05

Prescribed fire Trees per acre 1,817 200 133 131 126 118 110 300 154 151 141 131 116

Quadratic mean diameter (in) 5.4 16.0 19.4 20.6 22.0 23.4 24.9 13.2 18.2 19.3 20.8 22.4 24.1Total volume (ft3) 12,433 12,345 13,362 15,472 17,524 19,233 20,698 12,352 13,393 15,510 17,348 19,204 20,460Merchantable volume (ft3) 11,325 11,461 12,378 14,354 16,341 17,956 19,359 11,451 12,384 14,337 16,121 17,906 19,135Basal area (ft2) 289 280 274 305 333 353 369 284 276 309 334 358 369Stand density index 676 426 387 420 447 463 472 467 400 436 458 477 478Canopy cover (percent) 69 57 53 57 60 62 63 60 54 58 61 63 64

Crown competition factor 136 78 63 72 76 79 80 91 66 75 79 82 82Canopy base height (ft) 6 40 46 46 10 23 32 40 46 45 11 25 32Canopy bulk density (kg/m3) 0.05 0.04 0.05 0.05 0.05 0.05 0.05 0.04 0.05 0.05 0.05 0.05 0.05

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 2
K

225

Table 19d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 60 10 40 8 100 0 0

10 10 99 12 1 10 54 8 46

20 12 79 10 21 10 96 12 4

30 12 68 13 32 10 85 12 15

40 13 78 12 22 10 65 12 35

50 13 100 0 0 12 63 10 37

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 65 8 35 10 59 8 41

10 10 90 8 10 10 90 8 10

20 10 89 12 11 10 89 12 11

30 10 82 12 18 10 77 12 23

40 10 78 12 22 10 56 12 44

`50 10 68 12 32 12 81 10 19

Pile and burn 1 8 100 0 0 8 100 0 0

10 8 87 10 13 8 85 10 15

20 10 57 8 43 10 100 0 0

30 10 86 8 14 10 99 12 1

40 10 91 12 9 10 72 12 28

50 10 71 12 29 12 68 10 32

Prescribed fire 1 8 100 0 0 8 100 0 0

10 8 69 10 31 8 56 10 44

20 10 90 8 10 10 99 12 1

30 10 90 12 10 10 86 12 14

40 10 73 12 27 10 73 12 27

50 10 57 12 43 10 56 12 44

Region 5 — Sierra National Forest 2
L

226

Table 19f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 19e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 17 83 2 5 10 15 50 100Moderate—75th percentile 11 72 5 7 15 17 125 150Table 19d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 52 10 48 8 53 10 47

10 10 87 8 13 10 89 8 11

20 10 80 12 20 10 73 12 27

30 10 58 12 42 12 53 10 47

40 12 75 10 25 12 98 13 2

50 12 68 13 32 12 54 13 46

Pile and burn 1 8 100 0 0 8 100 0 0

10 8 83 10 17 8 81 10 19

20 10 100 0 0 10 100 0 0

30 10 83 12 17 10 73 12 27

40 12 55 10 45 12 84 10 16

50 12 82 13 18 13 52 12 48

Prescribed fire 1 8 100 0 0 8 100 0 0

10 10 54 8 46 10 58 8 42

20 10 96 12 4 10 94 12 6

30 10 87 12 13 10 83 12 17

40 10 71 12 29 10 63 12 37

50 10 52 12 48 12 60 10 40

tpa = trees per acre, d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 2
Initial stand conditions

A

227

Region 5 — Sierra National Forest 3

Site: Elevation = 4,600 ft, slope = 20 percent, aspect = 135°.Species (based on trees per acre): Hardwoods = 58 percent, white fir (Abies concolor) = 37 percent, sugar pine (Pinus lambertiana) = 3 percent, ponderosa pine (Pinus ponderosa) = 2 percent.

Stand attributes: Stem density = 1,991 tpa, basal area = 272 ft2/ac, top height = 112 ft, stand density index = 655, quadratic mean diameter = 5.0 in, crown competition factor = 103, canopy cover = 63 percent.
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

228

Region 5 — Sierra National Forest 3
C

229

Initial conditions/no-action trajectoryThis stand has 1,991 trees per acre (tpa) composed primarily of white fir and hardwood understory with ponderosa pine and sugar pine overstory. Canopy bulk density is 0.13 kg/m3 (0.0081 lb/ft3), and canopy base height is 6 ft, so ladder fuels are sufficient to enable passive crown fire, but active crown fire spread is unlikely under moderate and severe fire weather. Woody fuel loading is 18 tons/ac, and litter and duff loading is 22 tons/ac. Potential flame lengths are 4 ft, and potential basal area mortality is 87 percent for severe fire. With no action, canopy base height decreases and canopy bulk density increases in 10 years as smaller trees grow into the overstory, and active crown fire is predicted for severe fire weather. As trees grow and the stand self-thins, canopy base height increases and canopy bulk density decreases, so predicted fire type changes to passive crown fire for severe fire weather in 20 years and remains so for the 50-year projection. Surface fuels accumulate rapidly and flame lengths increase over time; in 50 years, flame lengths are 7 ft and 10 ft for moderate and severe fire weather, respectively. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment raises canopy base height and reduces crown fire potential, but it creates many snags that contribute to higher surface fuel loadings and potential flame lengths in 10 years. In the short term, all thinning treatments increase canopy base height, reducing crown fire potential. The greater the thinning, the more canopy base height increases, but there is little difference between the 200 and 300 tpa treatments. Only the lower density treatments reduce canopy bulk density. However, they increase surface fuels causing higher potential flame lengths; higher density treatments have little effect on surface fuels and flame lengths. The pile and burn and prescribed fire treatments reduce surface fuels, potential flame lengths, and basal area mortality. Mortality of smaller overstory trees in the prescribed fire treatment also further increases canopy base height. In the 50 tpa treatment, potential flame lengths remain high for severe fire weather despite reduction of activity fuels because the predominant fuel model is 5, suggesting that brush fuels would drive fire behavior in these open stands with low woody fuels. The FFE model does not track brush fuels directly, so results should be interpreted with caution. 

Silvicultural and surface fuel treatments—long-term effectsIn the prescribed fire only treatment, potential flame lengths increase over time as surface fuels accumulate, but canopy base height also increases, so predicted fire type remains surface fire for 50 years. Regeneration is sufficient to cause a decrease in canopy base height in 20 years in the 50 tpa treatment without surface fuel treatment and with prescribed fire, and in the 100 tpa treatment with prescribed fire. At this time, the predicted fire type becomes passive crown fire, but canopy base height increases again in 30 years and the fire type reverts to surface fire. Surface fuels and potential flame lengths increase over time in the 200 and 300 tpa treatment, but canopy base height also increases as trees grow and the stand self-thins, so crown fire potential remains low for the 50-year projection. Canopy bulk density remains low enough that active crown fire is unlikely in all treatments for the 50-year projection.

Region 5 — Sierra National Forest 3
D

230Table 20a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 4 1 9 6 4 4

3–6 in 7 1 6 7 7 76–12 in 7 3 5 6 7 7>12 in 0 0 0 0 0 0Litter 1 1 1 1 1 1Duff 21 15 17 19 20 21

Flame length (ft) Moderate 3 1 3 3 3 3

Severe 4 1 5 4 5 4

Torching index Severe 15 444 121 82 53 18Crowning index Severe 20 26 33 27 20 20Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 19 14 8 12 18 19

Severe 87 14 10 13 21 22

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 1 1

3–6 in 2 2 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 1 1 1 1Duff 15 17 18 19

Flame length (ft) Moderate 1 1 3 3

Severe 5 1 5 4

Torching index Severe 208 468 53 18Crowning index Severe 33 27 20 20Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 8 12 17 19

Severe 9 12 19 20

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 3 4 4 4>12 in 0 0 0 0Litter 1 1 1 1Duff 12 13 14 15

Flame length (ft) Moderate 1 1 1 1

Severe 5 1 1 1

Torching index Severe 166 456 439 444Crowning index Severe 36 32 26 26Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 8 11 13 14

Severe 9 11 13 14

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 5 — Sierra National Forest 3
E

231

Table 20b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 11 23 28 30 33 1 8 11 13 15 19

3–6 in 7 7 7 8 9 11 1 3 3 3 3 46–12 in 7 9 12 15 18 20 3 9 10 9 9 11>12 in 0 3 9 14 19 27 0 4 9 11 13 18Litter 1 2 2 2 2 2 1 1 1 1 1 1Duff 21 21 20 20 20 20 15 14 14 14 14 14

Flame length (ft) Moderate 3 3 6 7 7 7 1 3 4 5 5 6

Severe 4 5 8 9 10 10 1 5 6 7 8 9

Torching index Severe 15 0 4 6 13 23 444 134 121 101 118 101Crowning index Severe 20 14 18 20 23 20 26 27 29 29 29 31

Type of fire Moderate Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Active Passive Passive Passive Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 354 637 482 305 279 185 566 62 29 30 42 53

18–29.9 in 18 19 19 18 20 25 21 18 13 11 14 2230–36 in 5 5 5 5 6 7 5 5 4 4 4 5

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 9 9 9 10 10 11 6 9 11 13 15 18

3–6 in 6 5 5 4 4 3 7 6 5 5 4 46–12 in 5 6 7 6 5 5 6 7 7 7 7 8>12 in 0 3 6 7 8 8 0 3 6 8 9 14Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 17 16 16 16 15 15 19 18 18 18 18 17

Flame length (ft) Moderate 3 3 4 4 4 4 3 3 4 4 5 6

Severe 5 6 6 6 6 6 4 5 6 6 7 8

Torching index Severe 121 127 2 19 49 73 82 118 144 148 185 178Crowning index Severe 33 36 38 39 37 37 27 27 30 29 29 30Type of fire Moderate Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 70 53 21 11 9 9 71 54 23 21 28 43

18–29.9 in 17 15 11 8 6 6 17 15 11 9 11 1930–36 in 5 4 4 4 3 3 5 4 4 4 4 4

Region 5 — Sierra National Forest 3
F

232Table 20b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 5 6 8 9 10 2 5 9 12 14 17

3–6 in 2 2 2 2 2 2 2 2 2 2 2 36–12 in 2 3 4 4 3 3 2 3 4 4 5 6>12 in 0 3 6 7 7 7 0 3 6 7 9 13Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 15 15 14 14 14 14 17 17 16 16 16 16

Flame length (ft) Moderate 1 2 2 3 3 3 1 2 3 4 4 5

Severe 5 4 4 4 5 5 1 3 4 5 6 8

Torching index Severe 208 250 20 281 109 116 468 389 233 26 194 185Crowning index Severe 33 34 36 36 35 34 27 27 29 29 29 32Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 70 53 20 9 8 11 71 54 21 23 29 42

18–29.9 in 17 15 11 6 6 6 17 15 10 9 11 2130–36 in 5 4 4 3 3 3 5 4 4 4 4 5

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 4 6 8 9 11 0 5 8 10 12 14

3–6 in 2 2 2 2 2 2 2 3 3 2 2 26–12 in 3 5 6 5 5 4 4 7 8 7 7 7>12 in 0 4 9 10 10 10 0 4 9 11 12 13Litter 1 1 1 1 1 1 1 1 1 1 1 1Duff 12 11 11 11 11 11 17 13 13 13 12 12

Flame length (ft) Moderate 1 2 3 3 3 4 1 2 4 4 4 5

Severe 5 5 5 5 5 6 1 4 6 6 7 7

Torching index Severe 166 189 11 44 77 85 456 219 2 16 36 46Crowning index Severe 36 38 39 38 38 37 32 31 32 32 32 32Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 72 53 25 12 12 19 86 62 28 17 22 22

18–29.9 in 21 19 13 8 7 7 21 19 13 9 9 1030–36 in 5 5 4 4 3 3 5 5 4 4 4 3

Region 5 — Sierra National Forest 3
G

233

Table 20b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 9 14 18 21 22 4 9 14 19 24 25

3–6 in 7 6 6 6 7 7 7 6 6 6 8 86–12 in 7 8 9 11 14 18 7 8 9 11 16 21>12 in 0 3 7 10 15 23 0 3 7 10 17 25Litter 1 1 1 2 1 1 1 1 2 2 1 1Duff 20 20 20 19 19 19 21 20 20 20 20 20

Flame length (ft) Moderate 3 3 5 6 7 7 3 3 5 6 7 8

Severe 5 5 7 8 10 10 4 5 7 8 10 11

Torching index Severe 53 75 71 79 102 89 18 57 51 45 39 41Crowning index Severe 20 22 24 26 26 28 20 22 23 28 28 29Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 75 70 52 72 85 62 84 81 62 95 103 90

18–29.9 in 16 15 13 14 14 22 17 16 13 18 19 2130–36 in 5 4 4 4 5 5 5 4 4 5 5 6

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 7 13 17 21 22 1 7 13 18 23 25

3–6 in 2 2 3 3 4 5 2 2 3 4 5 66–12 in 2 4 6 8 12 16 2 4 6 8 13 19>12 in 0 3 7 10 15 23 0 3 7 10 17 25Litter 1 1 1 2 1 1 1 2 2 2 1 1Duff 18 18 18 17 17 17 19 18 18 18 18 18

Flame length (ft) Moderate 3 3 4 5 6 7 3 3 4 5 7 8

Severe 5 4 6 7 9 10 4 4 6 8 10 11

Torching index Severe 53 91 87 85 113 93 18 69 64 53 42 57Crowning index Severe 20 22 24 26 26 29 20 22 23 28 29 30Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 75 70 53 80 86 61 84 81 63 96 104 98

18–29.9 in 16 15 13 13 14 23 17 16 13 19 19 2030–36 in 5 4 4 4 5 5 5 4 4 5 5 5

Region 5 — Sierra National Forest 3
H

234

Table 20c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,991 1,312 914 677 453 352 139 138 135 122 106 89

Quadratic mean diameter (in) 5.0 6.6 8.2 9.8 12.0 13.6 5.0 18.8 20.5 22.6 24.9 27.2Total volume (ft 3) 10,448 12,846 14,967 16,818 17,804 18,189 10,597 12,351 15,948 18,736 20,441 21,058Merchantable volume (ft 3) 9,483 11,605 13,472 15,034 15,907 16,440 9,751 11,393 14,828 17,482 19,158 19,765Basal area (ft 2) 272 313 337 358 358 357 241 264 310 342 357 358Stand density index 655 675 668 660 610 580 352 378 428 454 457 442Canopy closure (percent) 63 78 78 77 72 69 50 52 57 59 59 58Crown competition factor 103 204 174 154 128 115 65 69 78 81 81 77Canopy base height (ft) 6 3 10 14 19 25 19 43 53 47 55 58Canopy bulk density (kg/m3) 0.13 0.22 0.16 0.13 0.11 0.13 0.09 0.09 0.08 0.08 0.08 0.07

Table 20b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 7 10 13 15 17 0 7 10 13 15 18

3–6 in 2 4 4 3 3 4 2 4 4 4 4 46–12 in 4 9 10 10 10 11 4 10 10 10 10 12>12 in 0 4 9 11 14 17 0 4 9 11 14 18Litter 1 1 1 1 1 2 1 1 1 1 1 1Duff 14 14 14 14 13 13 15 14 14 14 14 14

Flame length (ft) Moderate 1 3 4 5 5 6 1 3 4 5 5 6

Severe 1 5 6 7 8 9 1 5 6 7 8 9

Torching index Severe 439 136 122 15 141 128 444 133 124 16 130 103Crowning index Severe 26 26 29 29 29 31 26 26 28 29 29 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 101 62 34 34 41 47 124 62 38 36 46 62

18–29.9 in 21 19 14 11 13 21 21 18 14 11 14 2430–36 in 5 5 4 4 4 7 5 5 5 4 4 5

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 3
I

235

Table 20c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 947 55 153 150 146 143 140 100 147 144 140 135 130

Quadratic mean diameter (in) 7.0 23.4 14.2 14.5 14.9 15.3 15.7 19.6 16.6 17.2 17.8 18.4 19.0Total volume (ft3) 8,192 5,961 6,089 6,298 6,514 6,734 6,947 7,540 7,782 8,193 8,528 8,850 9,152Merchantable volume (ft3) 7,490 5,820 5,946 6,152 6,381 6,597 6,790 7,321 7,550 7,970 8,305 8,626 8,894Basal area (ft2) 252 163 167 173 178 184 189 210 221 232 241 249 257Stand density index 532 213 268 273 279 284 289 295 332 344 352 359 366Canopy cover (percent) 62 36 36 37 37 38 39 46 47 48 48 49 49Crown competition factor 215 117 120 123 126 131 135 151 156 162 166 170 174Canopy base height (ft) 3 54 54 54 51 52 5 28 35 39 39 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.08 0.09 0.10 0.10 0.10 0.10

Pile and burn Trees per acre 947 55 203 199 194 190 185 100 173 169 164 159 153

Quadratic mean diameter (in) 7.0 23.4 12.3 12.6 13.0 13.3 13.7 19.6 15.3 15.8 16.4 17.0 17.6Total volume (ft3) 8,192 5,961 6,089 6,297 6,524 6,733 6,964 7,540 7,782 8,161 8,527 8,868 9,174Merchantable volume (ft3) 7,490 5,820 5,946 6,152 6,390 6,597 6,799 7,321 7,550 7,939 8,304 8,642 8,913Basal area (ft2) 252 163 167 173 179 184 189 210 221 231 241 250 258Stand density index 532 213 283 289 295 301 307 295 343 353 363 371 378Canopy cover (percent) 62 36 36 37 37 38 40 46 47 48 48 49 49Crown competition factor 215 117 120 123 126 132 137 151 156 161 166 170 174Canopy base height (ft) 3 54 54 51 51 52 5 28 35 38 39 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.08 0.09 0.10 0.10 0.10 0.11

Prescribed fire Trees per acre 947 55 351 342 335 327 319 100 238 232 227 220 213

Quadratic mean diameter (in) 7.0 23.4 9.1 9.4 9.7 10.0 10.2 19.6 12.6 13.1 13.6 14.0 14.5Total volume (ft3) 8,192 5,691 5,813 6,011 6,228 6,450 6,667 7,109 7,330 7,701 8,090 8,414 8,729Merchantable volume (ft3) 7,490 5,557 5,677 5,876 6,103 6,316 6,504 6,908 7,120 7,499 7,881 8,204 8,488Basal area (ft2) 252 163 160 165 170 177 183 210 207 217 228 236 245Stand density index 532 213 303 309 317 325 332 295 347 358 370 379 387Canopy cover (percent) 62 36 35 36 37 39 41 46 45 46 47 47 48Crown competition factor 215 117 115 117 121 131 146 151 147 152 157 162 166Canopy base height (ft) 3 55 55 54 54 4 5 28 35 38 39 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.07 0.08 0.09 0.09 0.09 0.10

Region 5 — Sierra National Forest 3
J

236Table 20c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 947 200 211 199 191 181 170 300 308 291 274 252 228

Quadratic mean diameter (in) 7.0 15.0 14.9 15.6 16.3 16.9 17.5 12.4 12.5 13.2 13.9 14.5 15.2Total volume (ft3) 8,192 8,257 8,559 8,957 9,438 9,724 9,771 8,444 8,749 9,222 9,669 9,695 9,738Merchantable volume (ft3) 7,490 7,655 7,876 8,455 8,910 9,139 9,188 7,751 7,954 8,600 9,027 8,970 8,913Basal area (ft2) 252 245 254 264 276 283 283 250 264 276 288 287 286Stand density index 532 383 399 406 418 421 416 422 443 454 464 455 445Canopy cover (percent) 62 56 57 57 58 57 57 59 60 60 61 60 59

Crown competition factor 215 189 192 195 201 203 200 203 209 214 219 215 210Canopy base height (ft) 3 9 16 23 27 32 35 5 5 5 5 5 5Canopy bulk density (kg/m3) 0.13 0.13 0.11 0.11 0.12 0.13 0.14 0.13 0.12 0.12 0.13 0.13 0.14

Pile and burn Trees per acre 947 200 224 210 202 192 180 300 321 304 287 264 243

Quadratic mean diameter (in) 7.0 15.0 14.4 15.2 15.8 16.4 17.0 12.4 12.3 12.9 13.5 14.1 14.6Total volume (ft3) 8,192 8,257 8,559 8,955 9,440 9,732 9,782 8,444 8,749 9,243 9,533 9,582 9,633Merchantable volume (ft3) 7,490 7,655 7,876 8,453 8,912 9,146 9,198 7,751 7,954 8,618 8,888 8,853 8,787Basal area (ft2) 252 245 254 264 277 283 283 250 264 277 284 284 284Stand density index 532 383 404 411 423 427 421 422 446 459 463 456 448Canopy cover (percent) 62 56 57 57 58 57 57 59 60 61 61 60 59

Crown competition factor 215 189 192 195 201 203 200 203 209 215 217 213 210Canopy base height (ft) 3 9 16 23 27 32 35 5 5 5 5 5 5Canopy bulk density (kg/m3) 0.13 0.13 0.11 0.11 0.12 0.13 0.14 0.13 0.12 0.12 0.13 0.13 0.14

Prescribed fire Trees per acre 947 200 235 221 213 205 198 300 262 247 232 217 197

Quadratic mean diameter (in) 7.0 15.0 13.7 14.4 15.0 15.6 16.2 12.4 12.9 13.5 14.2 14.9 15.7Total volume (ft3) 8,192 7,856 8,164 8,539 8,988 9,460 9,910 7,688 8,021 8,407 8,752 9,090 9,270Merchantable volume (ft3) 7,490 7,362 7,601 8,121 8,560 8,987 9,445 7,205 7,463 7,979 8,321 8,599 8,766Basal area (ft2) 252 245 241 250 262 273 285 250 237 247 255 264 266Stand density index 532 383 390 397 409 420 431 422 393 402 408 412 408Canopy cover (percent) 62 56 54 54 55 55 56 59 54 54 54 54 54

Crown competition factor 215 189 179 183 189 194 200 203 180 184 187 190 189Canopy base height (ft) 3 9 16 23 27 32 35 9 6 6 6 6 35Canopy bulk density (kg/m3) 0.13 0.10 0.10 0.10 0.11 0.12 0.12 0.09 0.09 0.10 0.10 0.11 0.11

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 3
K

237

Table 20d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 100 0 0 8 100 0 0

10 10 78 12 22 10 98 12 2

20 12 69 13 31 10 60 12 40

30 13 92 12 8 12 59 10 41

40 13 100 0 0 12 80 10 20

50 13 100 0 0 12 77 13 23

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 10 99 5 1101 0 10 70 8 30

10 10 92 12 8 0 0 10 94 12 6

20 10 82 12 18 0 0 10 71 12 29

30 10 82 12 18 0 0 10 57 12 43

40 10 81 12 19 0 0 12 62 10 38

`50 10 80 12 20 0 0 12 98 13 2

Pile and burn 1 5 65 8 35 0 0 8 100 0 0

10 8 47 5 33 10 20 8 70 10 30

20 10 63 8 32 5 5 10 90 8 10

30 10 83 8 17 0 0 10 83 12 17

40 10 94 8 6 0 0 10 57 12 43

50 10 96 12 4 0 0 12 83 10 17

Prescribed fire 1 5 73 8 27 0 0 8 100 0 0

10 5 46 8 29 10 26 10 59 8 41

20 10 82 8 12 5 6 10 84 12 16

30 10 95 12 5 0 0 10 69 12 31

40 10 89 12 11 0 0 10 54 12 46

50 10 80 12 20 0 0 12 64 10 36

Region 5 — Sierra National Forest 3
L

238

Table 20f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 20e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 17 83 2 5 10 15 50 100Moderate—75th percentile 11 72 5 7 15 17 125 150Table 20d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 100 0 0 10 100 0 0

10 10 91 12 9 10 91 12 9

20 12 59 10 41 12 63 10 37

30 12 100 0 12 92 13 8

40 12 51 13 49 13 71 12 29

50 13 85 12 15 13 100 0 0

Pile and burn 1 10 100 0 0 10 100 0 0

10 10 100 0 0 10 100 0 0

20 10 74 12 26 10 70 12 30

30 12 74 10 26 12 86 10 14

40 12 66 13 34 13 55 12 45

50 13 72 12 28 13 100 0 0

Prescribed fire 1 8 100 0 0 8 100 0 0

10 10 100 8 0 10 98 12 2

20 10 60 12 40 10 60 12 40

30 12 63 10 37 12 61 10 39

40 12 85 10 15 12 84 10 16

50 12 87 13 13 12 76 13 24

tpa = trees per acre, d.b.h. = diameter at breast height.

Region 5 — Sierra National Forest 3
Initial stand conditions

A

239

Appendix 6—Fuel Treatment Scenarios for the Pacific Northwest Region (Region 6)

Region 6 — Deschutes National Forest 1

Site: Elevation = 4,700 ft, slope = 30 percent, aspect = 135°.Species (based on trees per acre): White fir (Abies concolor) = 99 percent, ponderosa pine (Pinus ponderosa) = 1 percent.

Stand attributes: Stem density = 1,345 tpa, basal area = 246 ft2/ac, top 

height = 106 ft, stand density index = 559, quadratic mean diameter = 5.8 in, crown competition factor = 195, canopy cover = 60 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

240

Region 6 — Deschutes National Forest 1
C

241

Initial conditions/no-action trajectoryThis stand has 1,345 trees per acre (tpa) composed of primarily white fir understory with a ponderosa pine overstory. Canopy base height is 4 ft, and canopy bulk density is 0.21 kg/m3 (0.0131 lb/ft3), so initial conditions are conducive to passive crown fire and active crown fire spread. Potential flame lengths and mortality are high especially for severe fire weather for which 100-percent basal area mortality is predicted. Woody fuel and duff loadings are high at 30 tons/ac and 20 tons/ac respectively. With no action, canopy base height increases and canopy bulk density decreases as the trees grow and the stand self-thins. Within 10 years, canopy bulk density decreases sufficiently to prevent active crown fire spread, but passive crown fire remains likely for the 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsPrescribed fire only increases canopy base height to 16 ft, reduces canopy bulk density to 0.10 kg/m3 (0.0062 lb/ft3), and decreases crown fire potential, but snag density doubles. Fuel loadings, potential flame lengths, and basal area mortality are also reduced. All thinning treatments effectively reduce canopy bulk density and increase canopy base height enough to reduce crown fire potential; the greater the thinning, the greater the reduction in fire hazard. Thinning without surface fuel treatments increases surface fuels; the greater the thinning, the greater are activity fuels and potential flame lengths. Pile and burn reduces woody surface fuels in all size classes, decreasing flame length and tree mortality. Prescribed fire reduces surface fuel loading even more, but reduces primarily litter, duff, and fine woody fuels. Woody fuel loading in the larger size classes remains high following prescribed fire, so fuel model 11 remains the predominant model and flame lengths are higher than in the pile and burn treatment.

Silvicultural and surface fuel treatments—long-term effectsCrown fire remains unlikely for the 50-year projection for all combinations of thinning and surface fuel treatments except the 50 tpa treatment, in which greater regeneration causes a decrease in canopy base height allowing for passive crown fire again in 50 years with no surface fuel treatment or with pile and burn, and in 40 years for the prescribed fire treatment. At this time, a second treatment would be necessary to reduce crown fire potential. It may seem contradictory that the treatment with the greatest reduction in surface fuel loading and tree density would have the most fleeting effect on crown fire potential, but this demonstrates the important influence of regeneration on crown fire potential as predicted with FFE. For all other treatments, canopy base height and canopy bulk density increase as the trees grow and the stand self-thins. 

Region 6 — Deschutes National Forest 1
D

242Table 21a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 6 4 12 9 8 7

3–6 in 5 1 7 7 6 5

6–12 in 7 3 7 7 7 7>12 in 12 8 12 12 12 12

Litter 2 1 4 3 3 3

Duff 20 14 20 20 20 20

Flame length (ft) Moderate 4 3 5 4 4 4

Severe 5 4 7 6 5 6

Torching index Severe 0 41 111 61 56 22Crowning index Severe 14 26 32 23 18 15

Type of fire Moderate Passive Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 45 10 5 10 14 18

Severe 100 12 10 13 17 21

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 2 2

3–6 in 2 2 2 26–12 in 2 2 2 2

>12 in 3 3 3 3

Litter 4 3 3 3Duff 18 18 18 18

Flame length (ft) Moderate 4 2 2 2

Severe 5 3 3 3

Torching index Severe 63 66 71 71

Crowning index Severe 32 23 18 15Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 5 9 13 14

Severe 5 10 13 15

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 3 3 2 2

6–12 in 7 7 7 7

>12 in 12 12 12 12Litter 1 1 1 1

Duff 4 4 0 0

Flame length (ft) Moderate 3 3 3 3

Severe 4 4 4 4

Torching index Severe 92 55 40 47Crowning index Severe 34 26 26 26

Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 5 8 10 10

Severe 5 9 11 11

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Deschutes National Forest 1
E

243

Table 21b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 6 6 6 6 6 6 4 6 5 4 4 4

3–6 in 5 7 8 8 8 8 1 5 5 5 5 56–12 in 7 11 15 15 14 14 3 11 13 13 12 11>12 in 12 18 23 28 29 30 8 15 21 25 26 24Litter 2 3 3 3 3 3 1 2 2 2 2 2Duff 20 21 21 21 21 21 14 14 14 15 15 15

Flame length (ft) Moderate 4 5 6 6 6 6 3 5 5 6 5 5

Severe 5 7 8 8 8 8 4 7 7 7 7 7

Torching index Severe 0 0 0 0 0 0 41 27 26 29 37 45Crowning index Severe 14 16 18 20 21 23 26 25 24 22 22 21Type of fire Moderate Passive Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Severe Active Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 222 277 188 164 132 113 440 75 43 23 15 12

18–29.9 in 25 23 19 13 10 8 27 23 17 10 6 430–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 12 7 4 3 3 3 9 6 4 4 4 4

3–6 in 7 8 9 8 7 6 7 8 9 8 7 76–12 in 7 12 14 13 12 10 7 12 15 14 12 11>12 in 12 17 22 25 25 23 12 17 22 25 26 25Litter 4 1 1 2 2 2 3 2 2 2 2 2Duff 20 21 21 20 20 20 20 21 21 21 21 21

Flame length (ft) Moderate 5 6 6 6 6 5 4 5 6 6 6 5

Severe 7 8 8 8 7 7 6 7 8 8 8 7

Torching index Severe 111 76 76 78 79 0 61 32 33 35 39 43Crowning index Severe 32 31 30 30 29 29 23 22 21 20 19 19Type of fire Moderate Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 143 101 34 19 11 9 144 102 38 24 17 13

18–29.9 in 24 22 16 10 6 3 24 21 15 10 7 530–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Region 6 — Deschutes National Forest 1
F

244Table 21b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 4 3 3 3 3 3 4 3 3 4 4

3–6 in 2 4 5 5 4 4 2 4 5 5 5 46–12 in 2 7 11 10 9 8 2 7 11 10 10 9>12 in 3 10 16 19 20 19 3 10 16 19 20 20Litter 4 1 1 2 2 2 3 2 2 2 2 2Duff 18 18 18 18 18 18 18 18 18 18 18 18

Flame length (ft) Moderate 4 3 4 5 4 4 2 3 4 5 5 5

Severe 5 5 6 6 6 6 3 5 6 6 6 6

Torching index Severe 63 120 91 89 90 2 66 64 46 45 48 51Crowning index Severe 32 31 30 30 29 29 23 22 21 20 19 19Type of fire Moderate Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 143 101 35 20 11 10 144 102 35 23 16 14

18–29.9 in 24 22 15 10 5 3 24 21 15 10 6 430–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 3 3 2 3 3 1 4 3 3 3 3

3–6 in 3 6 6 5 5 5 2 6 6 6 5 56–12 in 7 13 15 13 12 11 7 14 16 15 14 12>12 in 12 18 24 27 27 25 12 19 24 28 28 27Litter 1 1 1 1 2 2 3 2 2 2 2 2Duff 4 4 5 5 5 5 18 4 5 5 5 6

Flame length (ft) Moderate 3 5 6 6 5 5 3 5 6 6 6 6

Severe 4 7 8 8 7 7 4 7 8 8 8 7

Torching index Severe 92 79 76 78 0 0 55 32 32 33 36 40

Crowning index Severe 34 33 32 31 30 30 26 25 24 22 22 21Type of fire Moderate Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 103 64 36 26 20 15 119 74 43 28 19 15

18–29.9 in 27 24 17 10 6 3 27 23 17 11 7 430–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Region 6 — Deschutes National Forest 1
G

245

Table 21b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 8 6 5 5 5 6 7 6 5 6 6 6

3–6 in 6 7 8 8 7 7 5 7 8 8 7 76–12 in 7 11 14 14 13 13 7 11 15 14 14 13>12 in 12 17 22 26 26 26 12 17 23 26 27 27Litter 3 3 3 3 3 3 3 3 3 3 3 3Duff 20 21 21 21 21 21 20 21 21 21 21 21

Flame length (ft) Moderate 4 5 6 6 6 6 4 5 6 6 6 6

Severe 5 7 8 8 8 8 6 7 7 8 8 8

Torching index Severe 56 28 27 28 30 32 22 17 14 14 18 18Crowning index Severe 18 17 19 20 20 20 15 15 17 18 20 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 145 108 50 32 29 41 159 121 64 50 43 50

18–29.9 in 24 21 16 11 8 8 25 22 17 12 8 8

30–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 4 5 5 5 6 2 4 5 5 6 7

3–6 in 2 4 5 5 5 5 2 4 5 5 5 66–12 in 2 7 11 11 10 10 2 7 11 11 11 11>12 in 3 10 16 20 21 22 3 10 16 21 23 23Litter 3 3 3 3 3 3 3 3 3 3 3 3Duff 18 18 18 19 19 19 18 18 18 19 19 19

Flame length (ft) Moderate 2 3 4 5 5 5 2 3 5 5 5 5

Severe 3 4 6 7 7 7 3 5 6 7 7 7

Torching index Severe 71 58 38 38 38 38 71 37 24 22 25 23Crowning index Severe 18 17 19 20 20 21 15 15 17 18 20 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 145 108 50 31 31 43 159 121 65 50 43 52

18–29.9 in 24 21 16 10 8 8 25 22 17 12 8 8

30–36 in 2 2 2 1 1 1 2 2 2 1 1 1

Region 6 — Deschutes National Forest 1
H

246

Table 21c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,345 1,145 988 863 761 676 127 124 119 113 107 103

Quadratic mean diameter (in) 5.8 6.4 7.0 7.6 8.2 8.9 5.8 18.3 19.4 20.4 21.5 22.5Total volume (ft 3) 8,959 9,333 9,676 9,982 10,238 10,495 8,421 8,761 9,362 9,976 10,437 10,924Merchantable volume (ft 3) 8,280 8,584 8,851 9,352 9,717 9,961 8,014 8,321 8,881 9,605 10,125 10,582Basal area (ft 2) 246 257 266 274 282 290 217 227 243 259 271 284Stand density index 559 561 560 559 559 558 318 327 343 357 367 378Canopy closure (percent) 60 60 59 58 58 57 45 46 47 48 48 49Crown competition factor 195 193 191 190 189 189 141 145 152 159 163 168Canopy base height (ft) 4 5 6 6 6 7 16 18 19 21 24 27Canopy bulk density (kg/m3) 0.21 0.18 0.15 0.14 0.12 0.12 0.10 0.10 0.11 0.12 0.12 0.13

Table 21b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 4 4 4 4 4 1 5 4 4 4 4

3–6 in 2 7 7 6 6 5 2 7 7 6 6 66–12 in 7 14 16 15 14 12 7 14 16 15 14 12>12 in 12 19 24 28 28 27 12 19 24 28 28 27Litter 1 2 2 2 2 2 1 2 2 2 2 2Duff 0 0 1 1 2 2 0 0 1 1 2 2

Flame length (ft) Moderate 3 5 6 6 6 6 3 5 6 6 6 6

Severe 4 7 8 8 8 8 4 7 8 8 8 7

Torching index Severe 40 24 25 32 35 39 47 24 24 25 29 33Crowning index Severe 26 25 24 22 22 21 26 25 24 23 22 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 136 75 44 27 20 17 162 75 44 27 20 16

18–29.9 in 27 23 17 11 7 4 27 23 17 11 6 430–36 in 2 2 2 1 1 1 2 2 2 1 1 1

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 1
I

247

Table 21c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,345 50 149 145 141 137 132 100 147 142 135 129 124

Quadratic mean diameter (in) 5.8 26.0 15.6 16.2 16.9 17.6 18.2 20.1 17.2 18.1 19.1 19.9 20.8Total volume (ft3) 8,959 7,789 8,025 8,522 9,001 9,419 9,825 8,996 9,330 9,964 10,466 10,927 11,370Merchantable volume (ft3) 8,280 7,600 7,829 8,318 8,774 9,176 9,595 8,654 8,969 9,607 10,067 10,656 11,069Basal area (ft2) 246 184 196 208 219 230 240 220 238 255 267 279 291Stand density index 559 232 302 315 327 337 347 306 352 369 379 390 400Canopy cover (percent) 60 35 35 36 37 38 39 44 45 46 47 47 48

Crown competition factor 195 111 116 122 127 132 138 139 147 154 159 164 168Canopy base height (ft) 4 44 48 48 48 47 5 21 22 24 25 26 27

Canopy bulk density (kg/m3) 0.21 0.07 0.08 0.08 0.08 0.08 0.09 0.11 0.12 0.13 0.13 0.14 0.14

Pile and burn Trees per acre 1,345 50 199 194 188 184 178 100 173 169 162 155 149

Quadratic mean diameter (in) 5.8 26.0 13.5 14.1 14.6 15.2 15.8 20.1 15.9 16.7 17.5 18.3 19.1Total volume (ft3) 8,959 7,789 8,025 8,532 9,011 9,469 9,878 8,996 9,330 10,038 10,598 11,082 11,548Merchantable volume (ft3) 8,280 7,600 7,829 8,327 8,784 9,224 9,644 8,654 8,969 9,677 10,192 10,799 11,243Basal area (ft2) 246 184 196 208 220 231 241 220 238 257 271 284 296Stand density index 559 232 320 334 347 360 370 306 364 385 398 409 420Canopy cover (percent) 60 35 35 36 37 38 40 44 45 47 47 48 49

Crown competition factor 195 111 116 122 127 133 140 139 147 155 161 166 171

Canopy base height (ft) 4 44 48 48 48 47 5 21 22 24 25 26 27Canopy bulk density (kg/m3) 0.21 0.07 0.08 0.08 0.08 0.08 0.09 0.11 0.12 0.13 0.14 0.14 0.15

Prescribed fire Trees per acre 1,345 50 346 340 329 316 306 100 227 218 208 199 191

Quadratic mean diameter (in) 5.8 26.0 9.9 10.4 10.8 11.3 11.8 20.1 13.2 13.9 14.7 15.3 16.0Total volume (ft3) 8,959 7,417 7,641 8,158 8,598 8,991 9,403 8,297 8,597 9,174 9,677 10,131 10,575

Merchantable volume (ft3) 8,280 7,238 7,455 7,962 8,377 8,763 9,181 8,026 8,313 8,900 9,368 9,881 10,305Basal area (ft2) 246 184 187 199 210 220 231 220 217 231 244 255 267Stand density index 559 232 343 360 373 384 397 306 356 372 384 395 407Canopy cover (percent) 60 35 34 35 36 39 40 44 41 42 43 44 44Crown competition factor 195 111 111 117 122 132 140 139 132 139 144 149 154Canopy base height (ft) 4 44 48 48 48 4 5 21 22 24 25 26 28

Canopy bulk density (kg/m3) 0.21 0.07 0.07 0.08 0.08 0.08 0.08 0.10 0.10 0.11 0.12 0.12 0.13

Region 6 — Deschutes National Forest 1
J

248Table 21c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,345 200 216 199 188 171 150 300 301 272 245 220 190

Quadratic mean diameter (in) 5.8 14.7 14.9 15.9 16.9 18.0 19.2 12.2 12.6 13.7 14.7 15.8 17.0Total volume (ft3) 8,959 9,348 9,688 10,219 10,835 11,158 11,182 9,245 9,592 10,136 10,576 10,899 10,948Merchantable volume (ft3) 8,280 8,684 8,965 9,434 10,237 10,763 10,798 8,535 8,817 9,241 9,846 10,394 10,416

Basal area (ft2) 246 237 260 275 292 301 301 243 263 278 290 299 301

Stand density index 559 372 407 419 435 437 426 412 439 450 457 458 447

Canopy cover (percent) 60 52 54 54 55 55 53 57 58 58 58 57 56

Crown competition factor 195 163 174 179 185 187 182 180 187 191 193 194 189Canopy base height (ft) 4 15 18 20 21 22 23 12 13 14 15 17 17Canopy bulk density (kg/m3) 0.21 0.15 0.16 0.14 0.14 0.13 0.13 0.20 0.19 0.17 0.15 0.13 0.12

Pile and burn Trees per acre 1,345 200 229 211 200 181 158 300 314 284 256 230 198

Quadratic mean diameter (in) 5.8 14.7 14.4 15.5 16.4 17.5 18.7 12.2 12.4 13.4 14.4 15.5 16.7Total volume (ft3) 8,959 9,348 9,688 10,243 10,871 11,162 11,189 9,245 9,592 10,140 10,589 10,946 10,982Merchantable volume (ft3) 8,280 8,684 8,965 9,454 10,271 10,768 10,807 8,535 8,817 9,244 9,858 10,452 10,458

Basal area (ft2) 246 237 260 275 293 301 301 243 263 278 291 301 301Stand density index 559 372 412 425 442 442 431 412 443 454 461 464 451Canopy cover (percent) 60 52 54 55 55 55 53 57 58 58 58 58 56Crown competition factor 195 163 174 179 186 187 182 180 187 191 194 195 189

Canopy base height (ft) 4 15 18 20 21 22 23 12 13 14 15 17 17Canopy bulk density (kg/m3) 0.21 0.15 0.16 0.14 0.14 0.13 0.13 0.20 0.19 0.17 0.15 0.13 0.12

Prescribed fire Trees per acre 1,345 200 189 181 171 163 156 300 190 182 173 164 157

Quadratic mean diameter (in) 5.8 14.7 14.8 15.7 16.6 17.4 18.2 12.2 14.7 15.6 16.5 17.3 18.1Total volume (ft3) 8,959 8,428 8,755 9,361 9,896 10,371 10,834 8,403 8,724 9,345 9,876 10,374 10,855Merchantable volume (ft3) 8,280 8,024 8,319 8,887 9,503 10,070 10,520 8,017 8,319 8,899 9,472 10,066 10,517Basal area (ft2) 246 237 226 242 256 269 282 243 225 241 255 268 282Stand density index 559 372 355 372 385 397 408 412 354 371 384 396 408

Canopy cover (percent) 60 52 45 46 47 48 48 57 45 46 47 48 48

Crown competition factor 195 163 143 150 156 161 166 180 142 150 155 161 166

Canopy base height (ft) 4 15 18 20 24 25 26 18 18 20 21 22 23Canopy bulk density (kg/m3) 0.21 0.10 0.10 0.11 0.12 0.12 0.12 0.10 0.10 0.11 0.12 0.12 0.12

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 1
K

249

Table 21d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 10 74 12 26 10 67 9 30 2 4

10 12 66 10 34 10 52 12 48 0 0

20 12 98 13 2 12 68 10 32 0 0

30 12 87 13 13 12 75 10 25 0 0

40 12 85 13 15 12 71 10 29 0 0

50 12 86 13 14 12 64 10 36 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent

None 1 14 89 11 11 0 0 14 62 11 38

10 12 69 10 31 0 0 12 67 10 33

20 12 80 10 20 0 0 12 83 10 17

30 12 77 10 23 0 0 12 87 10 13

40 12 67 10 33 0 0 12 82 10 18

`50 12 55 10 45 0 0 12 73 10 27

Pile and burn 1 2 61 10 39 0 0 9 74 10 21 2 6

10 10 91 6 8 9 10 10 98 9 2

20 10 72 12 28 0 0 10 68 12 32

30 10 65 12 35 0 0 10 57 12 43

40 10 68 12 32 0 0 10 56 12 44

50 10 75 12 25 0 0 10 60 12 40

Prescribed fire 1 11 64 2 20 10 16 11 67 10 17 222 9 99 8

10 10 55 12 45 0 0 12 56 10 44

20 12 67 10 33 0 0 12 81 10 19

30 12 71 10 29 0 0 12 87 10 13

40 12 66 10 34 0 0 12 83 10 17

50 12 54 10 46 0 0 12 73 10 27

Region 6 — Deschutes National Forest 1
L

250

Region 6 — Deschutes National Forest 1

Table 21f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 21e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 90 3 5 8 15 50 100Moderate—75th percentile 9 71 5 8 11 24 125 150Table 21d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent Percent

None 1 11 61 14 39 0 0 0 0 10 69 12 31 0 0

10 12 62 10 38 0 0 0 0 12 65 10 35 0 0

20 12 89 10 11 0 0 0 0 12 92 10 8 0 0

30 12 95 10 5 0 0 0 0 12 97 13 3 0 0

40 12 96 10 4 0 0 0 0 12 95 13 5 0 0

50 12 97 10 3 0 0 0 0 12 94 13 6 0 0

Pile and burn 1 9 94 10 6 0 0 0 0 9 100 0 0 0 0

10 10 100 0 0 0 0 0 10 95 12 5 0 0

20 10 59 12 41 0 0 0 0 10 54 12 46 0 0

30 12 56 10 44 0 0 0 0 12 65 10 35 0 0

40 12 62 10 38 0 0 0 0 12 73 10 27 0 0

50 12 69 10 31 0 0 0 0 12 80 10 20 0 0

Prescribed fire 1 11 66 10 16 9 15 2 3 10 83 9 14 2 3

10 12 63 10 37 0 0 0 0 12 67 10 33 0 0

20 12 85 10 15 0 0 0 0 12 86 10 14 0 0

30 12 92 10 8 0 0 0 0 12 92 10 8 0 0

40 12 89 10 11 0 0 0 0 12 88 10 12 0 0

50 12 80 10 20 0 0 0 0 12 78 10 22 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

251

Region 6 — Deschutes National Forest 2

Site: Elevation = 5,300 ft, slope = 20 percent, aspect = 180o.Species (based on trees per acre): White fir (Abies concolor) = 83 percent, ponderosa pine (Pinus ponderosa) = 11 percent, lodgepole pine (Pinus contorta) = 6 percent.

Stand attributes: Stem density = 947 tpa, basal area = 252 ft2/ac, top height = 91 ft, stand density index = 532, quadratic mean diameter = 7.0 in, crown competition factor = 215, canopy cover = 62 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

252

Region 6 — Deschutes National Forest 2
C

253

Initial conditions/no-action trajectoryThis stand has 947 trees per acre (tpa) composed primarily of white fir understory with ponderosa pine and lodgepole pine overstory. Canopy bulk density is 0.13 kg/m3 (0.0081 lb/ft3), and canopy base height is 3 ft, so ladder fuels are sufficient to enable passive crown fire but not active crown fire under severe fire weather. Potential tree mortality under severe weather is 83 percent. Woody surface fuel loading is 15 tons/ac, and duff and litter loading is 12 tons/ac. With no action, surface fuels accumulate and flame lengths increase over time, and canopy base height increases only slightly with tree growth and self-thinning, so passive crown fire remains likely for the duration of the 50-year projection for severe fire weather. For moderate fire weather, the predicted fire type is surface fire for the 50-year projection.

Silvicultural and surface fuel treatments—immediate effectsPrescribed fire only increases canopy base height and reduces canopy bulk density and surface fuel loading, so crown fire potential decreases, but many snags are created that contribute to surface fuel loading in the future. All thinning treatments increase canopy base height, but the lower density treatments (50 and 100 tpa) increase canopy base height to a much greater extent than the higher density treatments (200 and 300 tpa) and also reduce canopy bulk density. The lower density treatments generate greater activity fuels and cause higher potential flame lengths. The pile and burn, and to a greater extent the prescribed fire surface fuel treatments, reduce activity fuels and potential flame lengths. In the 50 tpa treatment, fuel model 6 is the predominant model used, so flame lengths are predicted to be higher than initial conditions regardless of surface fuel treatment. 

Silvicultural and surface fuel treatments—long-term effectsCanopy base height continues to increase as trees grow in the 100, 200, and 300 tpa treatments, and regeneration is not sufficient to affect canopy base height, so crown fire potential remains low for the duration of the 50-year projection. Canopy base height also increases over time in the prescribed fire only treatment, and surface fire is predicted for 50 years. Regeneration is highest in the 50 tpa treatment so canopy base height declines in 40 or 50 years, at which time a second treatment would be necessary to prevent passive crown fire. Surface fuel loading and potential flame lengths remain fairly stable over time in stands treated with a pile and burn or prescribed fire treatment. All thinning prescriptions reduce canopy bulk density sufficiently that active crown fire remains unlikely for the 50-year projection. 

Region 6 — Deschutes National Forest 2
D

254Table 22a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 5 4 12 9 6 5

3–6 in 1 0 3 3 2 26–12 in 2 1 2 2 2 2>12 in 7 5 7 7 7 7Litter 2 1 4 3 2 2Duff 10 7 10 10 10 10

Flame length (ft) Moderate 2 2 4 3 2 2

Severe 3 3 5 3 3 3

Torching index Severe 7 35 254 209 26 16Crowning index Severe 22 30 52 32 22 22Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 16 12 5 9 14 16

Severe 83 12 5 9 15 17

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 2

3–6 in 1 1 1 06–12 in 0 0 0 0>12 in 2 2 2 2Litter 3 3 2 2Duff 9 9 9 9

Flame length (ft) Moderate 3 2 2 2

Severe 5 3 2 2

Torching index Severe 76 130 55 32Crowning index Severe 52 32 22 22Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 5 9 14 16

Severe 5 9 15 16

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 1 1 1 16–12 in 2 2 2 2>12 in 7 7 7 7Litter 0 1 1 1Duff 0 0 0 0

Flame length (ft) Moderate 3 2 2 2

Severe 5 3 3 2

Torching index Severe 72 103 121 49Crowning index Severe 55 37 30 30Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 5 8 11 12

Severe 6 8 11 12

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Deschutes National Forest 2
E

255

Table 22b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 5 5 5 5 5 5 4 5 4 4 3 3

3–6 in 1 2 2 3 3 4 0 3 3 3 3 36–12 in 2 2 3 4 5 6 1 5 6 6 6 6>12 in 7 7 7 8 9 9 5 6 7 7 8 8Litter 2 3 3 3 3 3 1 2 2 2 2 2Duff 10 10 10 10 11 11 7 7 7 7 8 8

Flame length (ft) Moderate 2 2 2 2 2 3 2 2 2 2 2 2

Severe 3 3 3 4 4 4 3 4 4 4 4 4

Torching index Severe 7 7 10 9 13 12 35 45 74 100 116 129Crowning index Severe 22 22 22 21 20 19 30 31 28 26 24 24Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 76 100 100 89 81 73 266 39 18 12 13 12

18–29.9 in 1 1 2 3 4 4 3 3 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 12 6 3 2 2 2 9 5 4 3 3 3

3–6 in 3 3 3 3 3 3 3 3 3 3 3 36–12 in 2 2 2 2 2 2 2 2 2 3 3 3>12 in 7 7 7 6 6 6 7 7 7 7 7 7Litter 4 1 1 1 1 1 3 2 2 2 2 2Duff 10 10 10 10 10 10 10 10 10 10 10 10

Flame length (ft) Moderate 4 3 4 4 3 3 3 2 2 2 2 2

Severe 5 5 5 5 5 5 3 4 3 3 3 3

Torching index Severe 254 125 122 111 108 8 209 101 114 122 123 122Crowning index Severe 52 51 50 49 49 49 32 28 26 26 25 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 36 26 10 6 6 6 38 28 12 9 11 11

18–29.9 in 1 1 1 2 2 2 1 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 2
F

256Table 22b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 2 2 2 2 3 3 3 3 3

3–6 in 1 1 1 1 2 2 1 1 1 2 2 26–12 in 0 1 1 2 1 1 0 1 2 2 2 2>12 in 2 2 3 3 3 4 2 2 3 4 4 4Litter 3 1 1 1 1 1 3 2 2 2 2 2Duff 9 9 9 9 9 9 9 9 9 9 9 9

Flame length (ft) Moderate 3 4 4 4 3 3 2 2 2 2 2 2

Severe 5 6 5 5 5 5 3 3 3 3 3 3

Torching index Severe 76 114 107 106 105 9 130 160 153 157 154 146Crowning index Severe 52 51 50 49 49 48 32 28 26 26 25 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 36 26 11 7 7 7 38 28 13 6 9 10

18–29.9 in 1 1 1 1 2 2 1 1 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 2 2 2 2 2 1 3 3 2 2 3

3–6 in 1 1 2 2 2 2 1 2 2 2 2 26–12 in 2 2 3 3 2 2 2 3 5 5 4 4>12 in 7 7 8 8 8 7 7 8 9 9 9 8Litter 0 1 1 1 1 1 3 1 1 2 2 2Duff 0 0 0 0 1 1 9 0 0 1 1 1

Flame length (ft) Moderate 3 4 4 4 3 3 2 3 2 2 2 2

Severe 5 6 6 5 5 4 3 4 4 3 3 3

Torching index Severe 72 121 125 119 6 9 103 84 100 108 113 113Crowning index Severe 55 53 52 51 51 50 37 32 30 29 29 28Type of fire Moderate Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 35 25 15 11 11 10 53 38 17 11 12 12

18–29.9 in 3 3 2 2 2 2 3 3 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 2
G

257

Table 22b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 6 5 5 4 4 5 5 5 5 4 5 5

3–6 in 2 2 3 3 3 3 2 2 2 3 3 46–12 in 2 2 3 4 4 5 2 2 3 4 4 5>12 in 7 7 7 8 8 8 7 7 7 7 7 9Litter 2 2 2 2 2 2 2 2 2 2 2 2Duff 10 10 10 10 10 11 10 10 10 10 11 11

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 3

Severe 3 3 3 3 3 4 3 3 3 3 4 4

Torching index Severe 26 54 78 93 111 118 16 16 16 16 14 12Crowning index Severe 22 24 24 23 21 21 22 22 22 21 21 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive

Hard snags (stems/ac) 0–17.9 in 51 42 28 18 17 32 48 43 30 26 46 50

18–29.9 in 1 1 2 2 2 4 1 1 1 2 4 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 4 4 4 4 5 2 4 4 4 5 5

3–6 in 1 1 2 2 2 3 0 1 1 2 2 36–12 in 0 1 2 3 4 4 0 1 2 3 4 5>12 in 2 3 4 4 5 6 2 2 3 4 5 6Litter 2 2 2 2 2 2 2 2 2 3 2 2Duff 9 9 9 9 9 10 9 9 9 9 9 10

Flame length (ft) Moderate 2 2 2 2 2 2 2 2 2 2 2 2

Severe 2 3 3 3 3 3 2 2 3 3 3 4

Torching index Severe 55 75 87 99 114 122 32 27 21 20 16 13Crowning index Severe 22 24 24 23 21 21 22 22 22 21 22 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 51 42 28 18 17 34 48 43 29 28 48 51

18–29.9 in 1 1 2 2 2 4 1 1 1 2 4 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 2
H

258

Table 22c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 947 865 785 712 647 588 150 148 144 139 133 128

Quadratic mean diameter (in) 7.0 7.4 7.9 8.4 8.9 9.4 7.0 16.7 17.3 18.0 18.7 19.4Total volume (ft 3) 8,192 8,636 8,916 9,194 9,466 9,756 7,383 7,664 8,125 8,489 8,854 9,222Merchantable volume (ft 3) 7,490 7,848 8,325 8,611 8,782 9,084 6,979 7,197 7,771 8,141 8,467 8,748Basal area (ft 2) 252 262 268 274 280 285 218 224 237 246 255 264Stand density index 532 539 538 538 537 535 329 336 349 357 365 373Canopy closure (percent) 62 62 62 61 61 61 50 50 51 52 52 53Crown competition factor 215 218 219 219 218 218 163 167 173 178 182 186

Canopy base height (ft) 3 3 4 4 5 5 9 15 24 32 37 41Canopy bulk density (kg/m3) 0.13 0.12 0.13 0.13 0.14 0.15 0.08 0.08 0.09 0.10 0.11 0.11

Table 22b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 4 3 3 3 3 1 4 3 3 3 3

3–6 in 1 3 3 3 3 3 1 3 3 3 3 36–12 in 2 6 7 6 6 6 2 6 7 7 6 6>12 in 7 8 9 9 9 8 7 8 9 9 9 9Litter 1 2 2 2 2 2 1 2 2 2 2 2Duff 0 0 1 1 1 1 0 0 1 1 1 1

Flame length (ft) Moderate 2 2 3 2 2 2 2 3 3 2 2 2

Severe 3 4 4 4 4 4 2 4 4 4 4 4

Torching index Severe 121 93 74 87 97 114 49 45 71 85 101 115Crowning index Severe 30 30 29 27 26 25 30 30 29 27 26 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 70 39 17 12 14 14 92 40 20 14 15 14

18–29.9 in 3 3 2 2 2 2 3 3 2 2 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 2
I

259

Table 22c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 947 55 153 150 146 143 140 100 147 144 139 134 130

Quadratic mean diameter (in) 7.0 23.4 14.2 14.5 14.9 15.3 15.7 19.6 16.6 17.2 17.8 18.5 19.1Total volume (ft3) 8,192 5,961 6,088 6,301 6,512 6,736 6,945 7,540 7,775 8,215 8,549 8,879 9,196Merchantable volume (ft3) 7,490 5,820 5,944 6,153 6,387 6,599 6,773 7,321 7,532 7,996 8,326 8,671 8,939Basal area (ft2) 252 163 167 173 178 183 189 210 221 233 242 250 258Stand density index 532 213 268 273 279 284 289 295 332 344 352 360 367Canopy cover (percent) 62 36 36 37 37 38 39 46 47 48 48 49 49Crown competition factor 215 117 120 123 126 131 135 151 156 162 166 170 174Canopy base height (ft) 3 54 54 54 51 52 5 28 35 38 39 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.08 0.09 0.10 0.10 0.10 0.11

Pile and burn Trees per acre 947 55 203 199 194 190 185 100 173 169 166 160 155

Quadratic mean diameter (in) 7.0 23.4 12.3 12.6 13.0 13.3 13.7 19.6 15.3 15.9 16.4 17.0 17.6Total volume (ft3) 8,192 5,961 6,088 6,300 6,520 6,735 6,960 7,540 7,775 8,186 8,609 8,980 9,317Merchantable volume (ft3) 7,490 5,820 5,944 6,153 6,391 6,599 6,789 7,321 7,532 7,969 8,383 8,769 9,057Basal area (ft2) 252 163 167 173 178 184 189 210 221 232 243 253 262Stand density index 532 213 283 289 295 301 307 295 343 354 367 376 384Canopy cover (percent) 62 36 36 37 37 38 40 46 47 48 49 49 50Crown competition factor 215 117 120 123 126 131 137 151 156 162 168 172 177Canopy base height (ft) 3 54 54 51 51 52 5 28 35 38 39 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.08 0.09 0.10 0.10 0.11 0.11

Prescribed fire Trees per acre 947 55 351 342 335 327 319 100 233 229 221 214 207

Quadratic mean diameter (in) 7.0 23.4 9.1 9.4 9.7 10.0 10.2 19.6 12.5 13.0 13.5 14.0 14.5Total volume (ft3) 8,192 5,691 5,814 6,014 6,223 6,454 6,664 6,883 7,085 7,489 7,800 8,126 8,435Merchantable volume (ft3) 7,490 5,557 5,678 5,878 6,103 6,320 6,494 6,690 6,873 7,298 7,600 7,937 8,207Basal area (ft2) 252 163 160 165 170 176 183 210 200 211 219 228 236Stand density index 532 213 303 310 317 324 332 295 335 348 357 365 374Canopy cover (percent) 62 36 35 36 37 39 41 46 43 44 45 46 46Crown competition factor 215 117 115 117 121 131 146 151 141 147 151 156 160Canopy base height (ft) 3 55 55 54 54 4 5 29 35 38 38 39 39Canopy bulk density (kg/m3) 0.13 0.04 0.04 0.04 0.04 0.04 0.04 0.06 0.08 0.08 0.08 0.09 0.09

Region 6 — Deschutes National Forest 2
J

260Table 22c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 947 200 211 199 191 183 166 300 308 291 274 242 214

Quadratic mean diameter (in) 7.0 15.0 14.9 15.6 16.3 17.0 17.8 12.4 12.5 13.2 13.9 14.8 15.7Total volume (ft3) 8,192 8,257 8,559 8,957 9,438 9,915 9,999 8,444 8,749 9,222 9,669 9,785 9,901Merchantable volume (ft3) 7,490 7,655 7,876 8,455 8,910 9,323 9,425 7,751 7,954 8,600 9,027 9,091 9,131Basal area (ft2) 252 245 254 264 276 288 288 250 264 276 288 288 288Stand density index 532 383 399 406 418 429 420 422 443 454 464 453 442Canopy cover (percent) 62 56 57 57 58 58 57 59 60 60 61 60 58

Crown competition factor 215 189 192 195 201 206 203 203 209 214 219 214 210Canopy base height (ft) 3 9 16 23 27 32 36 5 5 5 5 5 5Canopy bulk density (kg/m3) 0.13 0.13 0.11 0.11 0.12 0.13 0.13 0.13 0.12 0.12 0.13 0.13 0.13

Pile and burn Trees per acre 947 200 224 210 202 194 175 300 321 304 286 251 223

Quadratic mean diameter (in) 7.0 15.0 14.4 15.2 15.8 16.5 17.4 12.4 12.3 12.9 13.6 14.5 15.4Total volume (ft3) 8,192 8,257 8,559 8,955 9,440 9,917 10,001 8,444 8,749 9,243 9,677 9,783 9,906Merchantable volume (ft3) 7,490 7,655 7,876 8,453 8,912 9,324 9,424 7,751 7,954 8,618 9,033 9,082 9,134Basal area (ft2) 252 245 254 264 277 288 288 250 264 277 288 288 288Stand density index 532 383 404 411 423 433 424 422 446 459 468 456 445Canopy cover (percent) 62 56 57 57 58 58 57 59 60 61 61 60 58

Crown competition factor 215 189 192 195 201 206 203 203 209 215 219 214 210Canopy base height (ft) 3 9 16 23 27 32 36 5 5 5 5 5 5Canopy bulk density (kg/m3) 0.13 0.13 0.11 0.11 0.12 0.13 0.13 0.13 0.12 0.12 0.13 0.13 0.13

Prescribed fire Trees per acre 947 200 206 202 195 188 181 300 223 217 208 201 194

Quadratic mean diameter (in) 7.0 15.0 14.1 14.6 15.2 15.9 16.5 12.4 13.6 14.1 14.7 15.3 15.9Total volume (ft3) 8,192 7,369 7,642 8,136 8,555 8,972 9,380 7,385 7,660 8,119 8,518 8,917 9,351Merchantable volume (ft3) 7,490 6,982 7,201 7,797 8,206 8,602 9,037 6,981 7,201 7,760 8,144 8,518 8,906Basal area (ft2) 252 245 223 236 247 258 268 250 224 236 247 257 268Stand density index 532 383 357 372 384 394 404 422 364 378 388 399 409Canopy cover (percent) 62 56 50 51 52 52 53 59 50 51 52 53 53

Crown competition factor 215 189 164 171 177 181 187 203 166 173 178 183 189

Canopy base height (ft) 3 25 31 24 28 31 36 9 15 23 27 32 36Canopy bulk density (kg/m3) 0.13 0.08 0.08 0.09 0.10 0.10 0.11 0.08 0.08 0.09 0.10 0.10 0.11

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 2
K

261

Table 22d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 9 54 10 46 9 83 10 17

10 9 50 10 50 10 68 9 32

20 10 66 9 34 10 66 9 34

30 10 75 9 25 10 61 9 39

40 10 87 9 13 10 60 9 40

50 10 98 9 2 10 61 9 39

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 11 61 14 39 0 0 11 96 14 4 0 0

10 10 53 6 42 9 5 10 53 9 47 0 0

20 6 62 10 27 9 12 9 60 10 40 0 0

30 6 68 9 19 10 14 9 69 10 31 0 0

40 6 64 9 28 10 8 9 69 10 31 0 0

`50 6 58 9 36 10 6 9 66 10 34 0 0

Pile and burn 1 2 73 10 21 9 6 9 100 0 0 0 0

10 6 89 9 11 0 0 9 100 0 0 0 0

20 6 84 9 16 0 0 9 94 10 6 0 0

30 6 76 9 24 0 0 9 93 10 7 0 0

40 6 65 9 35 0 0 9 91 10 9 0 0

50 6 55 9 45 0 0 9 87 10 13 0 0

Prescribed fire 1 2 100 0 0 0 0 9 74 2 26 0 0

10 6 94 10 6 0 0 9 55 10 34 6 10

20 6 83 10 13 9 5 9 52 10 45 6 3

30 6 71 9 16 10 13 9 57 10 43 0 0

40 6 53 9 36 10 11 9 60 10 40 0 0

50 9 54 6 38 10 9 9 60 10 40 0 0

Region 6 — Deschutes National Forest 2
L

262

Region 6 — Deschutes National Forest 2

Table 22f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 22e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 90 3 5 8 15 50 100Moderate—75th percentile 9 71 5 8 11 24 125 150Table 22d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 11 63 9 37 10 51 9 49

10 10 56 9 44 9 51 10 49

20 10 61 9 39 10 53 9 47

30 10 61 9 39 10 54 9 46

40 10 64 9 36 10 70 9 30

50 10 78 9 22 10 95 9 5

Pile and burn 1 9 100 0 0 9 100 0 0

10 9 89 10 11 9 93 10 7

20 9 71 10 29 9 77 10 23

30 9 66 10 34 9 71 10 29

40 9 58 10 42 9 51 10 49

50 10 58 9 42 10 75 9 25

Prescribed fire 1 9 100 0 0 9 100 0 0

10 10 67 9 33 10 71 9 29

20 10 72 9 28 10 73 9 27

30 10 68 9 32 10 71 9 29

40 10 65 9 35 10 69 9 31

50 10 66 9 34 10 68 9 32

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

263

Region 6 — Deschutes National Forest 3

Site: Elevation = 5,000 ft, slope = 35 percent, aspect = 270°.Species (based on trees per acre): White fir (Abies concolor) = 93 percent, ponderosa pine (Pinus ponderosa) = 7 percent.

Stand attributes: Stem density = 544 tpa, basal area = 167 ft2/ac, top height = 84 ft, stand density index = 344, quadratic mean diameter = 7.5 in, crown competition factor = 153, canopy cover = 55 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

264

Region 6 — Deschutes National Forest 3
C

265

Initial conditions/no-action trajectoryThis stand has 544 trees per acre (tpa) composed of primarily white fir understory with ponderosa pine overstory. Canopy base height is 3 ft and canopy bulk density 0.14 kg/m3 (0.0087 lb/ft3), so there is high potential for passive crown fire and tree mortality but low potential for active crown fire spread under severe fire weather. Wood loading is 10 tons/ac, and litter and duff loading is 11 tons/ac. With no action, canopy base height will increase as trees grow and the stand selfthins, but flame lengths also increase as surface fuels accumulate, so crown fire potential remains essentially the same with passive crown fire likely. Canopy bulk density does not change for the 50-year projection, so the potential for active crown fire spread remains low. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment reduces tree density, which increases canopy base height enough to reduce crown fire potential, but it creates many more snags. This treatment also reduces woody surface fuels in all size classes, but potential flame lengths increase because conditions change from predominantly fuel model 9 to predominantly fuel model 2, suggesting that grass fuels drive fire behavior following the prescribed fire. This may or may not be true depending on the site. Thinning to 50 or 100 tpa greatly increases canopy base height and reduces canopy bulk density, thereby decreasing crown fire potential, but these treatments create high surface fuel loadings and increase potential flame lengths (fuel models change from predominantly 9 to predominantly 11). Thinning to 200 or 300 tpa is not sufficient to increase canopy base height, so these treatments have little effect on crown fire potential, but potential flame lengths remain low because removing fewer trees generates less activity fuels. The prescribed fire fuel treatment further decreases crown fire potential because fire-caused mortality of smaller trees further increases canopy base height. The pile and burn treatment reduces woody fuel loading to below initial conditions, and the prescribed fire treatment reduces woody fuel loading even more and consumes most of the duff layer, but these surface fuel treatments increase potential flame lengths because the more open stands with low woody fuel loading are characterized by fuel model 2. Again, grass fuels may or may not increase flame lengths depending on the site. Grass fuels are not tracked in FFE, so these results should be interpreted with caution.

Silvicultural and surface fuel treatments—long-term effectsReductions in crown fire potential last for 30 years in the 50 tpa treatment, but then regeneration lowers canopy base height making passive crown fire likely again; at this time, another treatment would be necessary to prevent passive crown fire. In the 100 tpa treatment, the influence of regeneration on canopy base height and crown fire potential depends on the surface fuel treatment with the greatest regeneration occurring in the prescribed fire treatment. In the 200 and 300 tpa treatments, regeneration is low and canopy base height increases over time as the stand self-thins and crowns rise, so after 50 years, crown fire remains unlikely except in the prescribed fire treatment in which passive crown fire becomes likely again in 40 years.

Region 6 — Deschutes National Forest 3
D

266Table 23a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 4 3 10 7 5 4

3–6 in 3 0 4 4 3 36–12 in 2 1 2 2 2 2>12 in 1 1 1 1 1 1Litter 2 1 4 3 3 2Duff 9 6 9 9 9 9

Flame length (ft) Moderate 2 3 3 3 2 2

Severe 3 5 4 4 3 3

Torching index Severe 5 17 141 70 3 4Crowning index Severe 19 25 43 22 19 19Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 24 19 11 17 22 24

Severe 98 31 11 17 97 98

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 2 2 1

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 4 3 2 2Duff 8 8 8 8

Flame length (ft) Moderate 4 4 2 2

Severe 7 6 3 3

Torching index Severe 33 49 11 11Crowning index Severe 43 22 19 19Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Passive Passive

Potential basal area mortality (%) Moderate 11 17 22 23

Severe 37 37 94 90

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 1 1 1

3–6 in 2 2 1 16–12 in 2 2 2 2>12 in 1 1 1 1Litter 1 1 1 1Duff 0 0 0 0

Flame length (ft) Moderate 4 4 4 3

Severe 7 6 5 5

Torching index Severe 34 37 39 19Crowning index Severe 50 29 25 25Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 10 15 19 19

Severe 38 43 35 31

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Deschutes National Forest 3
E

267

Table 23b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 5 6 6 6 6 3 5 4 4 4 4

3–6 in 3 3 4 5 5 6 0 3 3 3 4 46–12 in 2 2 4 6 8 9 1 6 6 6 6 7>12 in 1 2 4 5 7 10 1 2 4 5 7 8Litter 2 3 3 3 3 3 1 2 2 2 2 2Duff 9 9 10 10 10 10 6 7 7 7 7 7

Flame length (ft) Moderate 2 3 3 3 4 4 3 3 3 3 3 3

Severe 3 4 4 4 5 6 5 5 5 4 4 5

Torching index Severe 5 8 9 11 2 6 17 14 23 27 34 43Crowning index Severe 19 19 19 19 19 19 25 24 23 23 21 19

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 72 100 95 87 89 79 131 18 20 22 22 22

18–29.9 in 5 6 7 7 7 6 6 6 6 6 6 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 10 5 3 2 2 2 7 5 3 3 3 3

3–6 in 4 3 4 4 4 3 4 3 4 4 4 46–12 in 2 2 2 2 2 2 2 2 2 2 3 3>12 in 1 2 3 4 6 7 1 2 3 4 6 7Litter 4 1 1 1 1 1 3 2 2 2 2 2Duff 9 9 9 9 9 9 9 9 9 10 10 10

Flame length (ft) Moderate 3 5 5 5 5 5 3 4 4 4 4 3

Severe 4 7 7 7 7 6 4 6 5 5 5 5

Torching index Severe 141 64 65 0 7 12 70 70 72 73 75 14Crowning index Severe 43 40 38 37 35 34 22 22 22 22 21 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 18 14 11 13 13 13 19 17 12 16 18 17

18–29.9 in 5 6 6 6 6 5 5 6 6 6 6 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 3
F

268Table 23b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 2 2 2 2 2 3 3 3 3 3

3–6 in 1 1 2 2 2 2 1 1 2 2 2 26–12 in 1 1 1 1 1 2 1 1 1 2 2 3>12 in 0 1 3 4 5 6 0 1 2 4 5 7Litter 4 1 1 1 1 1 3 2 2 2 2 2Duff 8 8 8 8 8 8 8 8 8 8 9 9

Flame length (ft) Moderate 4 5 5 5 5 5 4 4 4 4 3 3

Severe 7 7 7 7 7 6 6 6 6 5 5 5

Torching index Severe 33 50 51 0 6 12 49 66 70 71 7 12Crowning index Severe 43 40 38 37 35 34 22 22 22 22 21 20Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Passive Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 18 14 12 15 15 15 19 17 15 19 19 17

18–29.9 in 5 6 6 6 6 5 5 6 6 6 6 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 2 2 2 2 2 1 3 2 2 2 3

3–6 in 2 2 2 3 3 3 1 3 3 3 3 36–12 in 2 3 3 3 3 3 2 5 5 5 5 5>12 in 1 3 4 6 7 8 1 3 4 5 7 8Litter 1 1 1 1 1 1 3 1 1 1 2 2Duff 0 0 0 1 1 1 8 0 0 1 1 1

Flame length (ft) Moderate 4 5 5 5 5 4 4 5 5 4 4 4

Severe 7 7 7 7 6 5 6 7 6 6 6 5

Torching index Severe 34 49 60 0 8 12 37 69 74 0 7 10Crowning index Severe 50 46 44 42 27 23 29 28 28 27 26 26Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Surface Surface Surface Surface Passive Passive Passive

Hard snags (stems/ac) 0–17.9 in 23 17 16 19 19 19 33 18 16 20 20 30

18–29.9 in 6 6 7 6 6 5 6 6 6 6 6 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 3
G

269

Table 23b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 5 5 5 5 6 6 4 5 6 6 6 6

3–6 in 3 3 4 4 5 5 3 3 4 4 5 66–12 in 2 2 3 5 7 9 2 2 3 5 8 10>12 in 1 2 3 5 7 9 1 2 3 5 7 10Litter 3 2 2 2 2 2 2 3 3 3 2 2Duff 9 9 10 10 10 10 9 9 10 10 10 10

Flame length (ft) Moderate 2 3 3 3 3 4 2 2 3 3 4 4

Severe 3 4 4 4 5 6 3 3 4 5 5 6

Torching index Severe 3 16 28 38 45 41 4 19 22 25 26 21Crowning index Severe 19 19 18 19 19 19 19 18 19 20 19 19Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 33 32 33 53 58 50 31 33 73 78 70 58

18–29.9 in 5 6 6 7 7 6 5 6 6 7 7 630–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 4 5 5 6 6 1 4 5 6 6 6

3–6 in 1 1 2 3 4 4 1 1 2 3 4 56–12 in 1 1 2 4 6 8 1 1 2 4 7 9>12 in 0 1 3 4 6 9 0 1 3 4 7 9Litter 2 2 2 2 2 2 2 3 3 3 2 2Duff 8 8 9 9 9 9 8 8 9 9 9 9

Flame length (ft) Moderate 2 2 2 3 3 4 2 2 3 3 3 4

Severe 3 3 3 4 5 5 3 3 4 4 5 6

Torching index Severe 11 26 33 40 49 77 11 29 25 26 31 27Crowning index Severe 19 19 18 19 19 19 19 18 19 20 19 19Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 33 32 33 56 60 53 31 33 74 79 71 60

18–29.9 in 5 6 6 7 7 6 5 6 6 7 7 630–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Deschutes National Forest 3
H

270

Table 23c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 544 450 386 328 270 221 151 150 142 134 127 119

Quadratic mean diameter (in) 7.5 8.4 9.3 10.1 11.2 12.4 7.5 13.2 14.0 14.9 15.9 16.8Total volume (ft 3) 5,004 5,325 5,616 5,817 5,899 5,950 4,306 4,541 4,932 5,328 5,729 6,097Merchantable volume (ft 3) 4,531 4,777 5,173 5,305 5,409 5,612 3,978 4,202 4,637 4,966 5,413 5,820Basal area (ft 2) 167 174 180 184 185 185 134 141 152 163 174 184Stand density index 344 341 340 335 324 311 223 232 244 255 266 275Canopy closure (percent) 55 54 53 53 51 49 40 41 42 43 43 44Crown competition factor 153 150 149 145 138 134 104 107 112 115 119 122Canopy base height (ft) 3 4 5 6 5 7 7 8 11 12 14 17Canopy bulk density (kg/m3) 0.14 0.14 0.14 0.14 0.14 0.14 0.10 0.10 0.11 0.11 0.12 0.14

Table 23b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 1 4 3 3 3 4 1 4 4 3 4 4

3–6 in 1 4 4 4 4 4 1 4 4 4 4 46–12 in 2 7 7 7 7 7 2 7 7 7 7 7>12 in 1 3 4 6 7 8 1 3 4 6 7 9Litter 1 2 2 2 2 2 1 2 2 2 2 2Duff 0 0 1 1 1 1 0 0 1 1 1 1

Flame length (ft) Moderate 4 4 3 3 3 3 3 3 3 3 3 3

Severe 5 5 5 5 5 5 5 5 5 5 5 5

Torching index Severe 39 51 70 79 6 12 19 24 27 32 6 12Crowning index Severe 25 24 24 23 22 21 25 24 25 24 22 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Passive Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 46 18 22 24 23 27 68 24 26 26 30 29

18–29.9 in 6 6 6 6 6 5 6 6 7 6 6 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 3
I

271

Table 23c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 544 50 148 143 138 133 127 100 146 143 136 129 122

Quadratic mean diameter (in) 7.5 18.8 11.2 11.6 12.2 12.8 13.6 15.3 13.1 13.8 14.6 15.5 16.5Total volume (ft3) 5,004 3,463 3,527 3,688 3,866 4,074 4,310 4,434 4,612 5,031 5,393 5,754 6,117

Merchantable volume (ft3) 4,531 3,342 3,423 3,574 3,737 3,948 4,161 4,212 4,425 4,811 5,155 5,558 5,906

Basal area (ft2) 167 96 100 105 112 119 128 127 137 148 159 170 181

Stand density index 344 137 176 182 190 198 207 198 226 239 250 261 272Canopy cover (percent) 55 25 25 26 28 30 31 36 37 38 39 40 41Crown competition factor 153 67 68 70 79 83 88 93 96 101 106 112 117Canopy base height (ft) 3 30 35 35 4 7 9 29 33 35 36 36 8Canopy bulk density (kg/m3) 0.14 0.05 0.05 0.06 0.06 0.06 0.07 0.12 0.12 0.12 0.12 0.12 0.13

Pile and burn Trees per acre 544 50 198 192 185 178 171 100 172 166 157 149 142

Quadratic mean diameter (in) 7.5 18.8 9.6 10.0 10.6 11.2 11.9 15.3 12.1 12.8 13.6 14.4 15.3Total volume (ft3) 5,004 3,463 3,527 3,691 3,874 4,094 4,353 4,434 4,612 5,000 5,356 5,726 6,107

Merchantable volume (ft3) 4,531 3,342 3,423 3,577 3,742 3,963 4,181 4,212 4,425 4,782 5,121 5,529 5,895Basal area (ft2) 167 96 100 106 113 121 131 127 137 147 158 169 181Stand density index 344 137 187 193 202 212 224 198 233 245 256 268 281Canopy cover (percent) 55 25 25 26 29 32 34 36 37 38 39 40 41Crown competition factor 153 67 68 70 83 88 94 93 96 100 106 113 119Canopy base height (ft) 3 30 35 35 4 7 9 29 33 35 36 5 7Canopy bulk density (kg/m3) 0.14 0.05 0.05 0.06 0.06 0.06 0.07 0.12 0.12 0.12 0.12 0.12 0.13

Prescribed fire Trees per acre 544 50 340 331 319 308 296 100 222 217 206 196 176

Quadratic mean diameter (in) 7.5 18.8 7.0 7.2 7.7 8.2 8.7 15.3 9.7 10.2 10.8 11.5 12.5Total volume (ft3) 5,004 3,142 3,184 3,304 3,456 3,647 3,883 3,777 3,897 4,201 4,482 4,791 4,979Merchantable volume (ft3) 4,531 3,039 3,095 3,206 3,332 3,501 3,681 3,606 3,755 4,034 4,298 4,622 4,789Basal area (ft2) 167 96 90 94 102 112 123 127 114 122 131 142 149

Stand density index 344 137 190 196 208 222 239 198 211 223 234 246 250Canopy cover (percent) 55 25 23 25 30 34 38 36 31 32 35 37 37

Crown competition factor 153 67 61 63 88 95 104 93 79 83 93 102 104Canopy base height (ft) 3 31 36 36 4 7 9 29 34 35 4 6 8Canopy bulk density (kg/m3) 0.14 0.04 0.05 0.05 0.05 0.09 0.13 0.08 0.09 0.09 0.09 0.10 0.10

Region 6 — Deschutes National Forest 3
J

272Table 23c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 544 200 207 190 161 137 118 300 304 251 208 174 147

Quadratic mean diameter (in) 7.5 12.1 12.3 13.3 14.5 15.7 16.9 10.1 10.5 11.6 12.7 14.0 15.2Total volume (ft3) 5,004 5,147 5,405 5,851 5,989 6,062 6,124 5,295 5,577 5,758 5,889 5,969 6,049Merchantable volume (ft3) 4,531 4,665 4,919 5,478 5,588 5,735 5,865 4,730 4,995 5,292 5,368 5,478 5,666Basal area (ft2) 167 161 172 183 184 184 185 166 182 183 184 184 185

Stand density index 344 273 290 300 292 283 276 303 327 317 307 296 288Canopy cover (percent) 55 48 49 49 47 45 43 52 54 52 50 47 45Crown competition factor 153 128 131 134 129 124 121 143 149 142 136 130 125

Canopy base height (ft) 3 3 6 10 14 17 33 3 6 8 10 13 15Canopy bulk density (kg/m3) 0.14 0.14 0.14 0.15 0.14 0.14 0.14 0.14 0.15 0.14 0.13 0.14 0.14

Pile and burn Trees per acre 544 200 220 202 170 144 123 300 317 261 215 179 150

Quadratic mean diameter (in) 7.5 12.1 12.0 12.9 14.1 15.3 16.6 10.1 10.3 11.4 12.5 13.8 15.0Total volume (ft3) 5,004 5,147 5,405 5,859 5,987 6,077 6,118 5,295 5,577 5,769 5,895 5,979 6,045Merchantable volume (ft3) 4,531 4,665 4,919 5,486 5,590 5,729 5,849 4,730 4,995 5,303 5,376 5,488 5,665Basal area (ft2) 167 161 172 183 184 185 185 166 182 184 184 185 185

Stand density index 344 273 293 304 295 286 277 303 330 320 309 298 289Canopy cover (percent) 55 48 49 49 47 45 43 52 54 52 50 47 45

Crown competition factor 153 128 131 134 129 125 121 143 149 143 136 130 125Canopy base height (ft) 3 3 6 10 14 18 33 3 6 8 10 13 15Canopy bulk density (kg/m3) 0.14 0.14 0.14 0.15 0.14 0.14 0.14 0.14 0.15 0.15 0.13 0.14 0.14

Prescribed fire Trees per acre 544 200 197 185 175 165 151 300 213 199 188 172 157

Quadratic mean diameter (in) 7.5 12.1 11.4 12.1 13.0 13.8 14.9 10.1 10.9 11.7 12.5 13.5 14.5Total volume (ft3) 5,004 4,280 4,492 4,863 5,280 5,694 6,009 4,296 4,456 4,822 5,241 5,589 5,919Merchantable volume (ft3) 4,531 3,973 4,192 4,629 4,988 5,436 5,791 3,969 4,138 4,545 4,897 5,273 5,661

Basal area (ft2) 167 161 139 148 160 172 181 166 138 148 160 170 179Stand density index 344 273 241 252 265 278 284 303 245 255 269 276 284

Canopy cover (percent) 55 48 39 40 41 43 43 52 40 41 42 43 43Crown competition factor 153 128 102 106 111 119 122 143 104 107 113 119 121Canopy base height (ft) 3 18 24 32 34 5 7 8 12 13 14 5 7

Canopy bulk density (kg/m3) 0.14 0.10 0.10 0.11 0.11 0.12 0.12 0.10 0.10 0.10 0.11 0.12 0.12

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Deschutes National Forest 3
K

273

Table 23d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 80 10 20 2 63 9 37 0 0

10 9 61 10 39 10 52 9 29 6 19

20 10 64 9 36 10 49 9 36 6 15

30 10 88 9 12 10 55 9 35 6 10

40 10 90 12 10 10 65 9 29 6 5

50 10 73 12 27 10 76 9 21 6 3

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 11 91 14 9 0 0 11 77 2 21 9 2

10 6 70 10 30 0 0 6 57 10 30 9 13

20 6 85 10 15 0 0 6 54 9 24 10 22

30 6 86 10 14 0 0 6 45 9 31 10 24

40 6 83 10 17 0 0 9 34 6 33 10 33

`50 6 78 10 22 0 0 10 44 9 34 6 23

Pile and burn 1 2 90 10 10 0 0 2 90 9 10 0 0

10 6 100 0 0 0 0 6 81 9 19 0 0

20 6 100 0 0 0 0 6 70 9 29 0

30 6 100 0 0 0 0 6 53 9 37 10 9

40 6 96 10 4 0 0 9 42 6 37 10 21

50 6 90 10 10 0 0 9 44 10 32 6 24

Prescribed fire 1 2 100 0 0 0 0 2 100 0 0 0 0

10 6 100 0 0 0 0 6 80 10 20 0 0

20 6 94 10 6 0 0 6 74 10 26 0 0

30 6 87 10 13 0 0 6 69 10 31 0 0

40 6 81 10 19 0 0 6 53 10 37 9 10

50 6 54 10 25 9 21 10 48 6 41 9 12

Region 6 — Deschutes National Forest 3
L

274

Region 6 — Deschutes National Forest 3

Table 23f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 23e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 90 3 5 8 15 50 100

9 71 5 8 11 24 125 150

Table 23d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 9 65 11 35 0 0 9 76 10 24 0 0

10 9 64 10 36 0 0 9 68 10 32 0 0

20 9 51 10 49 0 0 10 54 9 46 0 0

30 10 70 9 30 0 0 10 87 9 13 0 0

40 10 98 12 2 0 0 10 88 12 12 0 0

50 10 81 12 19 0 0 10 72 12 28 0 0

Pile and burn 1 9 100 0 0 0 0 9 100 0 0 0 0

10 9 93 10 7 0 0 9 95 10 5 0 0

20 9 72 10 28 0 0 9 65 10 35 0 0

30 10 52 9 48 0 0 10 71 9 29 0 0

40 10 87 9 13 0 0 10 97 12 3 0 0

50 10 88 12 12 0 0 10 79 12 21 0 0

Prescribed fire 1 2 76 9 24 0 0 2 65 9 35 0 0

10 10 48 6 30 9 22 10 52 9 24 6 24

20 10 52 9 25 6 23 10 58 9 25 6 17

30 10 60 9 26 6 14 10 65 9 25 6 10

40 10 67 9 25 6 8 10 78 9 17 6 5

50 10 83 9 14 6 4 10 93 9 6 6 1

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

275

Region 6 — Malheur National Forest 

Site: Elevation = 4,600 ft, slope = 29 percent, aspect = 140°.Species (based on trees per acre): Grand fir (Abies grandis) = 82 percent, Douglas-fir (Pseudotsuga menziesii) = 14 percent, ponderosa pine (Pinus ponderosa) = 3 percent, western larch (Larix occidentalis) = 2 percent.

Stand attributes: Stem density = 1,216 tpa, basal area = 174 ft2/ac, top height = 93 ft, stand density index = 415, quadratic mean diameter = 5.1 in, crown competition factor = 199, canopy cover = 69 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

276

Region 6 — Malheur National Forest 
C

277

Initial conditions/no-action trajectoryThis stand has 1,216 trees per acre (tpa) composed of primarily grand fir understory with Douglas-fir and ponderosa pine overstory. Canopy base height is 3 ft, and canopy bulk density is 0.21 kg/m3 (0.0131 lb/ft3), so initial conditions are conducive to active crown fire spread for severe fire weather but not for moderate fire weather. Similarly, potential tree mortality is high for severe fire weather but low for moderate fire weather. Woody fuel loading is 19 tons/ac, and litter and duff loading is 27 tons/ac. With no action, canopy base height will increase and canopy bulk density will decrease as trees grow and the stand self-thins, but passive crown fire remains likely for severe fire weather for 50 years. 

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment reduces crown fire potential, surface fuel loading, potential flame lengths, and potential mortality but creates many snags that will contribute to surface fuels in the future. All thinning treatments are effective at reducing canopy bulk density and increasing canopy base height enough to reduce the potential for active and passive crown fire. The greater the thinning, the greater the reduction in crown fire potential, but the differences between the 300 tpa treatment and the 200 tpa treatment are minor. All thinning treatments increase surface fuel loadings; the greater the thinning, the greater the activity fuels. These activity fuels increase potential flame lengths, but potential tree mortality remains lower than initial conditions because canopy base height is higher. The pile and burn and prescribed fire treatments reduce surface fuels to below initial conditions and decrease potential flame lengths and mortality more than thinning without surface fuel treatments. The prescribed fire treatment also partially reduces the duff layer, but it still remains at 17 tons/ac after the treatment. The flame lengths of the 50 tpa treatment with a pile and burn or prescribed fire are higher than other thinnings with the same surface fuel treatments, because the 50 tpa treatment is the most open stand, and conditions are characterized by predominantly fuel model 5 rather than fuel model 8. The importance of brush as a driver of fire behavior is not predicted well in FFE and is site specific, so this result should be interpreted with caution.

Silvicultural and surface fuel treatments—long-term effectsCrown fire remains unlikely for thinning treatments with a pile and burn or no surface fuel treatment for the 50-year projection, because flame lengths remain low, preventing passive crown fire even when regeneration causes canopy case height to decrease. Passive crown fire is predicted in 30 to 40 years for all treatments with prescribed fire, because these treatments have the greatest regeneration and therefore the biggest decrease in canopy base height when regeneration moves into the canopy. All treatments reduce canopy bulk density enough that active crown fire remains unlikely for the 50-year projection.

Region 6 — Malheur National Forest 
D

278Table 24a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 4 1 10 8 6 6

3–6 in 7 1 8 8 7 76–12 in 7 3 7 7 7 7>12 in 1 0 1 1 1 1Litter 2 1 3 3 3 3Duff 25 17 25 25 25 25

Flame length (ft) Moderate 2 1 4 3 3 2

Severe 3 1 6 5 4 3

Torching index Severe 10 155 109 90 63 46Crowning index Severe 14 35 36 30 25 22Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Active Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 25 16 9 14 18 21

Severe 100 16 15 20 22 24

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 2 2

3–6 in 2 2 2 26–12 in 2 2 2 2>12 in 0 0 0 0Litter 3 3 2 2Duff 23 23 23 23

Flame length (ft) Moderate 2 1 1 1

Severe 4 1 1 1

Torching index Severe 151 424 300 217Crowning index Severe 36 30 25 22Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 9 14 18 21

Severe 9 14 18 21

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 4 4 4 4>12 in 0 0 0 0Litter 1 1 1 1Duff 17 17 17 17

Flame length (ft) Moderate 2 1 1 1

Severe 6 1 1 1

Torching index Severe 106 472 273 259Crowning index Severe 40 35 35 35Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 9 12 15 15

Severe 13 12 15 15

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Malheur National Forest 
E

279

Table 24b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 4 5 5 6 6 1 5 3 3 3 3

3–6 in 7 7 7 6 6 5 1 4 4 4 3 36–12 in 7 8 9 9 8 8 3 7 8 8 8 3>12 in 1 2 4 5 6 7 0 3 5 7 8 3Litter 2 2 3 3 3 3 1 2 2 2 2 2Duff 25 25 25 25 25 25 17 17 17 17 17 17

Flame length (ft) Moderate 2 2 3 3 3 3 1 2 2 2 2 2

Severe 3 3 4 4 4 4 1 4 4 4 4 4

Torching index Severe 10 14 2 7 7 12 155 39 46 59 82 113Crowning index Severe 14 15 17 18 17 15 35 33 30 28 25 24Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Active Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 65 62 54 55 50 44 308 34 23 13 11 10

18–29.9 in 5 4 4 4 4 4 7 6 5 4 4 430–36 in 0 0 0 0 1 1 0 0 0 0 1 1

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 10 5 3 2 2 2 8 4 3 2 3 3

3–6 in 8 8 8 7 6 5 8 8 8 7 6 66–12 in 7 8 9 9 8 7 7 8 9 9 8 7>12 in 1 2 4 5 5 6 1 2 4 5 6 6Litter 3 1 1 1 1 1 3 1 2 2 2 2Duff 25 25 25 24 24 24 25 25 25 25 24 24

Flame length (ft) Moderate 4 3 3 3 2 2 3 3 3 3 3 2

Severe 6 5 5 4 4 4 5 4 4 4 4 4

Torching index Severe 109 90 121 9 24 36 90 91 102 123 157 17Crowning index Severe 36 36 37 38 38 37 30 29 28 28 28 26Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 51 38 14 8 6 6 51 39 16 9 7 7

18–29.9 in 5 5 4 3 3 3 5 4 4 3 3 330–36 in 0 0 0 0 0 0 0 0 0 0 0 1

Region 6 — Malheur National Forest 
F

280Table 24b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 2 2 2 2 2 2 2 2 2 3

3–6 in 2 3 3 3 3 3 2 3 3 3 3 36–12 in 2 4 5 6 5 5 2 4 5 6 5 5>12 in 0 2 3 5 5 5 0 2 3 5 5 6Litter 3 1 1 1 1 1 3 1 2 2 2 2Duff 23 22 22 22 22 22 23 22 22 22 22 22

Flame length (ft) Moderate 2 1 1 2 2 2 1 1 2 2 2 2

Severe 4 4 3 2 2 2 1 2 2 3 3 3

Torching index Severe 151 271 388 38 62 67 424 483 311 288 31 39

Crowning index Severe 36 36 37 38 37 37 30 29 28 28 27 26Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 51 38 14 8 7 7 51 39 16 9 8 8

18–29.9 in 5 5 4 3 2 3 5 4 4 3 3 330–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 2 2 2 0 2 2 2 2 2

3–6 in 2 3 3 3 3 3 2 4 4 4 3 36–12 in 4 7 8 8 7 6 4 8 9 9 8 7>12 in 0 3 5 7 7 7 0 3 5 7 7 7Litter 1 1 1 1 1 1 3 1 1 1 2 2Duff 17 17 17 17 17 17 23 17 17 17 17 17

Flame length (ft) Moderate 2 2 2 2 2 2 1 2 2 2 2 2

Severe 6 5 3 3 3 3 1 3 4 4 4 3

Torching index Severe 106 126 13 22 33 45 472 220 168 8 22 25Crowning index Severe 40 40 41 34 27 23 35 34 33 32 32 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Passive Surface Surface Surface Surface Surface Surface Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 42 28 18 11 9 9 52 33 20 10 8 7

18–29.9 in 7 6 5 3 3 2 7 6 5 4 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Malheur National Forest 
G

281

Table 24b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 6 4 3 3 3 4 6 4 3 3 4 4

3–6 in 7 7 7 7 6 5 7 7 7 6 6 56–12 in 7 8 9 9 8 8 7 8 9 9 8 8>12 in 1 2 4 5 6 6 1 2 4 5 6 6Litter 3 2 2 2 2 2 3 2 2 2 3 3Duff 25 25 25 25 25 25 25 25 25 25 25 25

Flame length (ft) Moderate 3 3 3 3 3 3 2 3 3 3 3 3

Severe 4 4 4 4 4 4 3 4 4 4 4 4

Torching index Severe 63 64 81 91 125 141 46 42 47 80 90 110Crowning index Severe 25 23 22 21 20 19 22 23 22 20 18 17Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 53 41 19 12 11 11 54 43 21 15 13 12

18–29.9 in 5 4 4 4 3 4 5 4 4 4 3 330–36 in 0 0 0 0 0 1 0 0 0 0 0 1

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 3 3 3 3 4 2 3 3 3 4 4

3–6 in 2 3 3 3 3 3 2 3 3 3 3 36–12 in 2 4 5 6 6 5 2 4 5 6 5 5>12 in 0 2 3 5 6 6 0 2 3 5 6 6Litter 2 2 2 2 2 2 2 2 2 2 3 3Duff 23 22 22 22 22 22 23 22 22 22 22 22

Flame length (ft) Moderate 1 1 2 2 2 2 1 1 2 2 2 2

Severe 1 2 3 3 3 3 1 2 3 3 3 3

Torching index Severe 300 293 220 194 226 246 217 190 130 154 162 202Crowning index Severe 25 23 22 21 20 18 22 23 22 20 18 16Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 53 41 19 12 11 11 54 43 21 14 13 14

18–29.9 in 5 4 4 4 3 4 5 4 4 3 3 430–36 in 0 0 0 0 0 1 0 0 0 0 0 1

Region 6 — Malheur National Forest 
H

282

Table 24c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,216 1,186 1,149 1,105 1,067 1,033 209 206 201 197 192 187

Quadratic mean diameter (in) 5.1 5.5 5.9 6.3 6.7 7.1 5.1 11.5 12.3 13.1 13.9 14.7Total volume (ft 3) 4,813 5,830 6,890 7,943 9,013 10,110 4,446 4,847 5,680 6,540 7,416 8,275Merchantable volume (ft 3) 4,041 4,945 5,927 6,864 7,762 8,651 3,965 4,343 5,141 5,927 6,674 7,446Basal area (ft 2) 174 198 220 241 262 283 139 148 166 184 202 220Stand density index 415 459 497 530 562 594 246 257 281 303 326 347Canopy closure (percent) 69 71 74 75 77 78 47 48 51 53 55 57Crown competition factor 199 215 228 239 250 261 115 120 131 141 151 161Canopy base height (ft) 3 4 4 5 5 6 7 8 10 13 17 22Canopy bulk density (kg/m3) 0.21 0.18 0.16 0.14 0.15 0.18 0.06 0.07 0.08 0.08 0.09 0.10

Table 24b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 2 2 2 3 0 4 3 2 2 3

3–6 in 2 5 4 4 4 3 2 5 5 4 4 36–12 in 4 8 9 9 8 7 4 8 9 9 8 7>12 in 0 3 5 7 7 7 0 3 5 7 7 7Litter 1 1 1 2 2 2 1 1 2 2 2 2Duff 17 17 17 17 17 17 17 17 17 17 17 17

Flame length (ft) Moderate 1 2 2 2 2 2 1 2 2 2 2 2

Severe 1 3 4 4 4 4 1 4 4 4 4 4

Torching index Severe 273 107 106 120 19 21 259 87 88 90 13 21Crowning index Severe 35 34 31 29 28 26 35 33 31 29 27 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 69 33 20 10 8 8 88 33 21 11 8 8

18–29.9 in 7 6 5 4 3 3 7 6 5 4 3 330–36 in 0 0 0 0 0 1 0 0 0 0 0 1

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Malheur National Forest 
I

283

Table 24c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,216 50 149 146 144 141 139 100 148 145 143 140 137

Quadratic mean diameter (in) 5.1 20.4 12.3 13.0 13.7 14.5 15.2 16.0 13.9 14.9 15.8 16.7 17.6Total volume (ft3) 4,813 4,186 4,484 5,108 5,693 6,245 6,740 4,880 5,315 6,242 7,199 8,157 9,053

Merchantable volume (ft3) 4,041 3,894 4,176 4,760 5,317 5,820 6,254 4,470 4,867 5,756 6,671 7,558 8,401Basal area (ft2) 174 113 124 136 148 161 174 140 157 175 194 213 232Stand density index 415 157 209 224 240 255 271 213 252 274 297 319 340Canopy cover (percent) 69 31 32 34 37 39 42 42 44 47 49 51 53Crown competition factor 199 75 80 87 101 109 117 103 113 123 134 145 158Canopy base height (ft) 3 34 37 38 4 6 7 21 27 27 30 34 5Canopy bulk density (kg/m3) 0.21 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.08 0.08 0.08 0.08 0.09

Pile and burn Trees per acre 1,216 50 199 196 192 189 186 100 174 171 168 165 162

Quadratic mean diameter (in) 5.1 20.4 10.7 11.3 11.9 12.6 13.2 16.0 12.9 13.7 14.6 15.4 16.3Total volume (ft3) 4,813 4,186 4,484 5,108 5,701 6,284 6,769 4,880 5,315 6,252 7,217 8,179 9,081Merchantable volume (ft3) 4,041 3,894 4,176 4,760 5,320 5,850 6,275 4,470 4,867 5,764 6,688 7,579 8,426Basal area (ft2) 174 113 124 136 149 163 176 140 157 175 195 214 233Stand density index 415 157 221 237 255 273 289 213 261 284 307 331 352Canopy cover (percent) 69 31 32 35 38 41 44 42 44 47 49 51 53Crown competition factor 199 75 80 87 106 115 123 103 113 123 134 146 160Canopy base height (ft) 3 34 37 38 4 6 6 21 27 27 30 4 5

Canopy bulk density (kg/m3) 0.21 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.08 0.08 0.08 0.09 0.09

Prescribed fire Trees per acre 1,216 50 343 338 332 327 321 100 225 221 217 213 209

Quadratic mean diameter (in) 5.1 20.4 7.8 8.2 8.7 9.2 9.7 16.0 10.5 11.2 11.9 12.6 13.3Total volume (ft3) 4,813 3,833 4,101 4,659 5,224 5,731 6,211 4,306 4,669 5,445 6,234 7,053 7,799Merchantable volume (ft3) 4,041 3,572 3,821 4,339 4,860 5,308 5,725 3,965 4,302 5,051 5,784 6,548 7,256Basal area (ft2) 174 113 113 124 138 151 166 140 135 151 167 185 202Stand density index 415 157 228 246 267 287 307 213 243 264 286 310 331Canopy cover (percent) 69 31 29 34 41 45 48 42 38 41 44 47 49Crown competition factor 199 75 73 81 113 123 133 103 95 104 118 135 145Canopy base height (ft) 3 35 38 3 4 5 6 24 29 29 3 5 6Canopy bulk density (kg/m3) 0.21 0.05 0.05 0.05 0.06 0.09 0.11 0.06 0.07 0.07 0.07 0.07 0.07

Region 6 — Malheur National Forest 
J

284Table 24c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 1,216 200 220 215 210 206 201 300 318 311 304 297 292

Quadratic mean diameter (in) 5.1 12.0 12.1 13.0 13.9 14.9 15.8 10.0 10.3 11.1 11.9 12.7 13.5Total volume (ft3) 4,813 5,138 5,635 6,734 7,933 9,213 10,493 5,209 5,723 6,846 8,085 9,426 10,818Merchantable volume (ft3) 4,041 4,491 4,970 6,038 7,213 8,310 9,497 4,485 4,950 6,043 7,206 8,269 9,474Basal area (ft2) 174 156 176 199 222 247 272 162 184 208 234 261 289

Stand density index 415 266 299 328 358 388 417 298 334 366 400 435 470Canopy cover (percent) 69 52 54 57 59 62 64 57 60 63 66 68 70

Crown competition factor 199 127 138 151 164 178 191 144 157 171 186 202 218

Canopy base height (ft) 3 12 16 19 21 27 32 8 10 11 17 19 25Canopy bulk density (kg/m3) 0.21 0.10 0.11 0.11 0.12 0.13 0.14 0.11 0.11 0.12 0.13 0.15 0.16

Pile and burn Trees per acre 1,216 200 233 228 223 218 213 300 331 324 317 309 303

Quadratic mean diameter (in) 5.1 12.0 11.8 12.6 13.5 14.4 15.3 10.0 10.1 10.9 11.6 12.4 13.2Total volume (ft3) 4,813 5,138 5,635 6,742 7,941 9,215 10,492 5,209 5,723 6,854 8,105 9,440 10,773Merchantable volume (ft3) 4,041 4,491 4,970 6,045 7,219 8,308 9,493 4,485 4,950 6,049 7,220 8,289 9,439Basal area (ft2) 174 156 176 199 223 248 272 162 184 208 234 261 287

Stand density index 415 266 303 332 362 393 422 298 337 369 404 439 472

Canopy cover (percent) 69 52 54 57 60 62 64 57 60 63 66 68 70Crown competition factor 199 127 138 151 164 178 191 144 157 171 187 202 217Canopy base height (ft) 3 12 16 19 21 27 32 8 10 11 16 19 26Canopy bulk density (kg/m3) 0.21 0.10 0.11 0.11 0.12 0.13 0.14 0.11 0.11 0.12 0.13 0.15 0.16

Prescribed fire Trees per acre 1,216 200 187 183 180 176 173 300 205 201 198 194 190

Quadratic mean diameter (in) 5.1 12.0 11.8 12.7 13.5 14.4 15.3 10.0 11.4 12.2 13.0 13.9 14.8Total volume (ft3) 4,813 4,410 4,798 5,654 6,565 7,528 8,454 4,428 4,826 5,699 6,622 7,602 8,572Merchantable volume (ft3) 4,041 3,976 4,337 5,188 6,051 6,941 7,830 3,971 4,349 5,193 6,065 6,899 7,897Basal area (ft2) 174 156 143 160 179 200 219 162 145 164 183 204 225

Stand density index 415 266 245 268 292 317 340 298 253 277 303 329 354Canopy cover (percent) 69 52 43 45 48 51 53 57 45 48 50 53 55

Crown competition factor 199 127 105 115 126 142 153 144 110 121 133 147 161Canopy base height (ft) 3 13 18 21 25 5 5 12 16 18 19 4 5Canopy bulk density (kg/m3) 0.21 0.06 0.06 0.07 0.08 0.08 0.09 0.06 0.07 0.07 0.08 0.09 0.10

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Malheur National Forest 
K

285

Table 24d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 10 56 8 44 8 100 0 0

10 10 69 8 31 10 53 8 47

20 10 95 8 5 10 60 8 40

30 10 96 12 4 10 66 8 34

40 10 94 12 6 10 66 8 34

50 10 92 12 8 10 66 8 34

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 11 65 14 35 0 0 11 82 14 18

10 10 84 8 11 5 5 10 82 8 18

20 10 71 8 26 5 3 10 76 8 24

30 10 63 8 37 0 0 10 73 8 27

40 10 53 8 47 0 0 10 68 8 32

`50 8 55 10 45 0 0 10 64 8 36

Pile and burn 1 8 50 5 39 10 11 8 98 10 2

10 8 67 5 32 0 8 95 10 5

20 8 83 10 12 5 4 8 81 10 19

30 8 82 10 18 0 0 8 73 10 27

40 8 83 10 17 0 0 8 70 10 30

50 8 84 10 16 0 0 8 68 10 32

Prescribed fire 1 5 73 8 27 0 0 8 100 0 0

10 5 51 8 35 10 13 8 70 10 30

20 8 66 10 28 5 7 8 56 10 44

30 8 64 10 36 0 0 10 52 8 48

40 8 66 10 34 0 0 8 50 10 50

50 8 70 10 30 0 0 8 55 10 45

Region 6 — Malheur National Forest 
L

286

Table 24f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 24e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 90 2 5 8 15 50 100Moderate—75th percentile 9 71 5 7 10 23 125 150

Region 6 — Malheur National Forest 

Table 24d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 11 98 14 2 11 88 8 12

10 10 77 8 23 10 74 8 26

20 10 77 8 23 10 78 8 22

30 10 80 8 20 10 81 8 19

40 10 80 8 20 10 86 8 14

50 10 82 8 18 10 89 8 11

Pile and burn 1 8 100 0 0 8 100 0 0

10 8 92 10 8 8 90 10 10

20 8 76 10 24 8 73 10 27

30 8 64 10 36 8 61 10 39

40 8 57 10 43 8 52 10 48

50 10 50 8 50 10 57 8 43

Prescribed fire 1 8 100 0 0 8 100 0 0

10 8 57 10 43 8 51 10 49

20 10 54 8 46 10 58 8 42

30 10 61 8 39 10 63 8 37

40 10 59 8 41 10 60 8 40

50 10 57 8 43 10 58 8 42

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

287

Region 6 — Okanogan and Wenatchee National Forests 1

Site: Elevation = 4,400 ft, slope = 34 percent, aspect = 220°.Species (based on trees per ac): Douglas-fir (Pseudotsuga menziesii) = 90 percent, ponderosa pine (Pinus ponderosa) = 9 percent.

Stand attributes: Stem density = 764 tpa, basal area = 174 ft2/ac, top height = 90 ft, stand density index = 379, quadratic mean diameter = 6.5 in, crown competition factor = 204, canopy cover = 65 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

288

Region 6 — Okanogan and Wenatchee National Forests 1
C

289

Region 6 — Okanogan and Wenatchee National Forests 1

Initial conditions/no-action trajectoryThis stand has 764 trees per acre (tpa) composed of primarily understory Douglas-fir with overstory ponderosa pine. Canopy base height is only 2 ft and canopy bulk density is 0.08 kg/m3 (0.005 lb/ft3), so initial conditions have high potential for passive crown fire and low potential for active crown fire spread under severe fire weather. Potential basal area mortality is 70 percent for severe fire weather, but only 18 percent for moderate fire weather. Woody fuel loading is 9 tons/ac, and litter and duff loading is 7 tons/ac. With no action, canopy base height increases as the trees grow and the stand self­-thins, making passive crown fire unlikely in 10 years, but crown fire potential declines only slightly because flame lengths increase as surface fuels accumulate.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment has little effect on canopy base height and crown fire potential and creates more snags. Surface fuel loading is reduced, but potential flame lengths increase because the more open stand is characterized by predominantly fuel model 6, brush fuels. Brush fuels are not tracked in FFE and the presence of brush following prescribed fire is site specific, so these results should be interpreted with caution. All thinning treatments increase canopy base height and reduce canopy bulk density. The 100 tpa thinning without a surface fuel treatment is the only treatment that remains susceptible to passive crown fire. Thinning to 50 tpa increases canopy base height much more than the other prescriptions because some larger overstory trees are removed as well as ladder fuels. All thinning treatments increase surface fuels, the greater the thinning, the greater is the increase in surface fuel loading. The 100 tpa treatment demonstrates that thinning must increase canopy base height enough to compensate for higher flame lengths associated with activity fuels if no surface fuel treatment is applied. The pile and burn treatment and, to a greater extent, the prescribed fire treatment reduce surface fuels, but flame lengths remain high because the low-density stands with scarce surface fuels are predominantly characterized by fuel model 6.

Silvicultural and surface fuel treatments—long-term effectsCanopy bulk density remains low enough in all treatments that active crown fire is unlikely for the 50-year projection. In the prescribed fire only treatment, crown fire potential decreases over time, and passive crown fire becomes unlikely in 10 years and remains unlikely for the 50-year projection. In all thinned stands, canopy base height continues to increase as trees grow and the stand self-thins, and passive crown fire remains unlikely for 50 years in the 100, 200, and 300 tpa treatments. Abundant regeneration causes a drop in canopy base height in 30 years in the 50 tpa treatments with a pile and burn and with no surface fuel treatment, and in 10 years in the 50 tpa treatment with prescribed fire. At this time, passive crown fire is predicted again, but the increase in crown fire potential is fleeting and soon decreases as the regeneration grows and crowns rise. Surface fuels accumulate over time in all thinned stands with pile and burn or prescribed fire treatments, but potential flame lengths decrease as the stand becomes less open and the assigned fuel model shifts from model 6 to model 9.
D

290Table 25a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 7 6 4 4

3–6 in 3 0 3 3 3 36–12 in 3 1 1 2 2 2>12 in 0 0 0 0 0 0Litter 2 1 3 3 2 2Duff 5 4 3 3 5 5

Flame length (ft) Moderate 2 3 4 4 3 2

Severe 3 5 6 6 4 3

Torching index Severe 0 10 81 26 12 17Crowning index Severe 29 48 50 45 33 31Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Passive Surface Surface Passive Surface

Potential basal area mortality (%) Moderate 18 16 6 11 16 17

Severe 70 36 7 20 30 21

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 1 1 1

3–6 in 1 1 1 16–12 in 0 1 1 1>12 in 0 0 0 0Litter 3 3 2 2Duff 2 3 4 4

Flame length (ft) Moderate 4 4 3 2

Severe 7 6 4 3

Torching index Severe 61 20 13 20Crowning index Severe 50 45 33 31Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 6 12 15 17

Severe 15 25 26 20

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 0 1 1 1Duff 2 2 3 3

Flame length (ft) Moderate 4 4 4 4

Severe 7 6 6 5

Torching index Severe 49 29 18 12Crowning index Severe 53 48 48 47Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Passive

Potential basal area mortality (%) Moderate 6 10 14 16

Severe 15 24 25 33

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Okanogan and Wenatchee National Forests 1
E

291

Table 25b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 5 7 7 7 7 1 4 4 5 5 5

3–6 in 3 3 4 5 5 6 0 3 3 3 4 56–12 in 3 2 3 4 5 6 1 3 3 4 5 6>12 in 0 0 1 2 3 4 0 1 2 3 4 5Litter 2 3 3 3 3 3 1 2 2 2 2 2Duff 5 5 6 6 7 7 4 4 4 4 5 5

Flame length (ft) Moderate 2 2 3 3 3 3 3 3 3 3 3 3

Severe 3 3 4 4 4 5 5 5 5 5 5 5

Torching index Severe 0 11 16 19 21 21 10 29 42 60 39 97Crowning index Severe 29 30 29 30 33 35 48 45 44 41 40 41Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 42 106 115 92 86 76 164 12 23 33 35 34

18–29.9 in 0 1 1 1 1 1 1 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 7 5 3 3 3 3 6 4 4 4 4 5

3–6 in 3 3 3 3 3 3 3 3 3 4 4 46–12 in 1 1 1 1 2 2 2 2 2 2 3 3>12 in 0 0 0 1 1 2 0 0 0 1 1 2Litter 3 1 2 2 2 2 3 2 2 2 2 2Duff 3 3 3 3 3 4 3 4 4 4 5 5

Flame length (ft) Moderate 4 4 4 4 2 2 4 4 4 4 4 3

Severe 6 7 7 6 3 3 6 6 6 5 5 5

Torching index Severe 81 94 93 0 25 32 26 52 57 75 89 98

Crowning index Severe 50 48 48 47 47 47 45 43 42 42 42 41Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 2 6 8 9 10 1 3 9 13 21 24

18–29.9 in 0 0 0 0 0 1 0 0 0 0 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 1
F

292Table 25b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 2 2 2 3 1 2 3 4 4 5

3–6 in 1 1 1 2 2 2 1 1 1 2 2 36–12 in 0 0 1 1 1 1 1 1 1 1 2 3>12 in 0 0 0 1 1 2 0 0 0 1 2 3Litter 3 1 2 2 2 2 3 2 2 2 2 2Duff 2 2 3 3 3 3 3 3 4 4 4 4

Flame length (ft) Moderate 4 4 4 2 2 2 4 4 4 4 4 4

Severe 7 7 7 3 3 3 6 6 6 6 6 5

Torching index Severe 61 75 78 15 27 39 20 47 53 74 89 8Crowning index Severe 50 48 48 47 47 47 45 43 42 41 41 41Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive

Hard snags (stems/ac) 0–17.9 in 1 2 6 9 12 14 1 3 10 19 26 27

18–29.9 in 0 0 0 0 0 1 0 0 0 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 2 2 3 4 0 2 3 3 3 4

3–6 in 1 1 1 2 2 2 1 2 2 2 3 36–12 in 1 1 1 2 2 2 1 2 3 3 3 4>12 in 0 1 1 2 3 4 0 1 2 3 3 4Litter 0 1 2 2 2 2 3 2 2 2 2 2Duff 2 2 2 2 3 3 3 3 3 3 3 4

Flame length (ft) Moderate 4 2 2 2 2 2 4 4 4 4 2 2

Severe 7 3 3 3 3 4 6 6 6 6 4 4

Torching index Severe 49 0 16 27 30 29 29 37 63 4 13 14Crowning index Severe 53 50 37 30 27 27 48 45 44 43 44 44Type of fire Moderate Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Passive Surface Surface Surface Surface Surface Surface Surface Passive Surface Surface

Hard snags (stems/ac) 0–17.9 in 7 7 13 17 34 44 15 10 14 12 21 31

18–29.9 in 1 1 1 1 1 2 1 1 1 0 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 1
G

293

Table 25b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 4 5 5 6 6 7 4 4 6 6 7 7

3–6 in 3 3 3 4 5 6 3 3 3 4 5 66–12 in 2 2 3 4 5 7 2 2 3 3 5 6>12 in 0 0 1 2 3 5 0 0 1 1 2 4Litter 2 3 3 3 3 2 2 3 3 3 3 3Duff 5 5 5 5 6 6 5 5 6 6 6 7

Flame length (ft) Moderate 3 3 3 3 3 3 2 2 2 3 3 3

Severe 4 4 4 5 5 5 3 3 4 4 4 5

Torching index Severe 12 36 52 74 90 84 17 31 43 36 40 39Crowning index Severe 33 39 39 39 38 39 31 33 32 35 35 36Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 14 20 34 42 45 43 15 25 38 48 55 55

18–29.9 in 0 0 1 1 2 2 0 0 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 3 5 6 6 6 1 3 5 6 7 7

3–6 in 1 1 2 3 4 5 1 1 2 3 4 56–12 in 1 1 1 3 4 6 1 1 1 2 3 5>12 in 0 0 1 2 3 5 0 0 1 1 2 3Litter 2 3 3 3 3 2 2 3 3 3 3 3Duff 4 4 5 5 5 6 4 5 5 5 6 6

Flame length (ft) Moderate 3 3 3 3 3 3 2 2 2 2 3 3

Severe 4 4 4 5 5 5 3 3 3 4 4 4

Torching index Severe 13 35 50 70 83 102 20 48 49 38 41 51Crowning index Severe 33 38 38 39 38 39 31 33 31 34 35 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 14 20 34 43 46 45 15 25 38 47 52 53

18–29.9 in 0 0 1 1 2 3 0 0 1 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 1
H

294

Table 25c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 764 651 571 506 446 394 186 182 168 149 133 117

Quadratic mean diameter (in) 6.5 7.2 7.8 8.4 9.0 9.7 6.5 12.6 13.5 14.4 15.4 16.5Total volume (ft 3) 5,287 5,717 5,994 6,350 6,635 6,954 4,981 5,273 5,621 5,854 6,093 6,301Merchantable volume (ft 3) 4,494 4,912 5,110 5,576 5,857 6,190 4,360 4,663 4,922 5,231 5,430 5,654

Basal area (ft 2) 174 184 189 196 199 203 150 158 166 169 171 172

Stand density index 379 384 383 384 379 377 255 265 271 268 264 260Canopy closure (percent) 65 66 64 64 63 62 49 50 50 49 48 46

Crown competition factor 204 207 208 208 206 204 144 151 156 155 153 150Canopy base height (ft) 2 4 6 7 8 9 6 13 18 24 16 34

Canopy bulk density (kg/m3) 0.08 0.08 0.08 0.08 0.07 0.07 0.04 0.05 0.05 0.05 0.05 0.05

Table 25b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 4 4 5 5 0 4 4 5 5 5

3–6 in 1 3 3 4 4 5 1 3 3 4 4 56–12 in 1 3 3 4 5 6 1 3 3 4 5 6>12 in 0 1 2 3 3 5 0 1 2 3 4 5Litter 1 2 2 2 2 2 1 2 3 3 2 2Duff 3 3 4 4 4 5 3 4 4 4 5 5

Flame length (ft) Moderate 3 3 3 3 3 3 2 3 3 3 3 3

Severe 4 5 5 5 5 5 3 5 5 5 5 5

Torching index Severe 12 32 55 67 77 11 17 25 44 61 76 92Crowning index Severe 33 45 44 41 40 40 31 45 44 41 40 40Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 28 11 20 28 35 34 47 12 28 39 42 38

18–29.9 in 1 1 1 1 1 2 1 1 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Okanogan and Wenatchee National Forests 1
I

295

Table 25c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 764 50 149 146 141 135 128 100 148 143 137 126 116

Quadratic mean diameter (in) 6.5 20.3 12.1 12.5 13.2 14.0 14.8 16.1 13.8 14.5 15.2 16.0 16.8Total volume (ft3) 5,287 4,344 4,502 4,758 5,128 5,505 5,835 5,138 5,378 5,765 6,191 6,458 6,635Merchantable volume (ft3) 4,494 3,956 4,155 4,343 4,712 5,030 5,346 4,549 4,813 5,099 5,474 5,720 5,883Basal area (ft2) 174 112 119 124 134 144 152 142 154 163 172 176 178Stand density index 379 155 202 209 221 231 239 215 249 259 267 268 266Canopy cover (percent) 65 29 30 31 35 37 38 41 42 43 44 43 43Crown competition factor 204 88 93 96 109 116 122 121 130 136 141 143 144Canopy base height (ft) 2 41 45 45 4 7 9 13 23 25 32 37 40Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.05

Pile and burn Trees per acre 764 50 199 195 189 179 168 100 174 168 158 143 130

Quadratic mean diameter (in) 6.5 20.3 10.5 10.8 11.5 12.2 13.0 16.1 12.8 13.3 14.0 14.9 15.7Total volume (ft3) 5,287 4,344 4,502 4,759 5,131 5,515 5,863 5,138 5,378 5,766 6,084 6,357 6,494Merchantable volume (ft3) 4,494 3,956 4,155 4,345 4,713 5,036 5,361 4,549 4,813 5,100 5,392 5,638 5,764Basal area (ft2) 174 112 119 124 135 146 155 142 154 163 169 173 174Stand density index 379 155 214 221 235 247 257 215 257 267 271 271 268Canopy cover (percent) 65 29 30 31 36 39 40 41 42 43 43 43 43Crown competition factor 204 88 93 96 112 121 128 121 130 136 138 141 142Canopy base height (ft) 2 41 45 46 4 6 9 13 23 25 32 37 6Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.05

Prescribed fire Trees per acre 764 50 345 336 323 293 259 100 227 218 212 199 178

Quadratic mean diameter (in) 6.5 20.3 7.8 8.3 9.0 9.8 10.7 16.1 10.5 10.9 11.5 12.1 13.0Total volume (ft3) 5,287 4,088 4,236 4,525 4,919 5,118 5,459 4,668 4,873 5,173 5,566 5,813 6,025Merchantable volume (ft3) 4,494 3,722 3,910 4,094 4,439 4,554 4,776 4,168 4,400 4,620 4,976 5,160 5,366

Basal area (ft2) 174 112 114 127 144 153 161 142 136 143 152 159 163Stand density index 379 155 231 251 274 283 288 215 245 252 265 270 270Canopy cover (percent) 65 29 34 41 46 48 48 41 37 38 40 42 42Crown competition factor 204 88 97 120 135 141 145 121 112 116 126 134 136Canopy base height (ft) 2 42 2 4 6 8 11 19 22 28 5 5 7Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.06 0.08 0.09 0.10 0.04 0.05 0.05 0.05 0.05 0.05

Region 6 — Okanogan and Wenatchee National Forests 1
J

296Table 25c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 764 200 206 182 160 138 119 300 300 273 241 209 180

Quadratic mean diameter (in) 6.5 12.2 12.5 13.5 14.4 15.4 16.4 10.2 10.6 11.5 12.4 13.3 14.2Total volume (ft3) 5,287 5,475 5,692 6,005 6,217 6,363 6,418 5,558 5,833 6,289 6,649 6,873 7,018

Merchantable volume (ft3) 4,494 4,723 4,982 5,214 5,543 5,666 5,765 4,736 5,018 5,351 5,818 6,081 6,270Basal area (ft2) 174 163 174 180 180 179 176 169 185 196 201 201 199Stand density index 379 276 293 294 286 277 265 308 331 341 339 329 318Canopy cover (percent) 65 53 54 53 51 49 47 59 61 61 60 58 55

Crown competition factor 204 160 168 169 166 160 154 178 191 198 198 192 185Canopy base height (ft) 2 6 14 20 27 30 33 5 8 12 11 13 26Canopy bulk density (kg/m3) 0.08 0.07 0.06 0.06 0.06 0.06 0.06 0.08 0.07 0.07 0.07 0.06 0.06

Pile and burn Trees per acre 764 200 219 194 169 147 126 300 313 285 254 223 193

Quadratic mean diameter (in) 6.5 12.2 12.1 13.1 14.0 15.0 16.0 10.2 10.4 11.2 12.1 13.0 13.9Total volume (ft3) 5,287 5,475 5,692 6,005 6,204 6,363 6,421 5,558 5,833 6,290 6,680 6,984 7,124Merchantable volume (ft3) 4,494 4,723 4,982 5,213 5,536 5,668 5,771 4,736 5,018 5,352 5,856 6,175 6,349Basal area (ft2) 174 163 175 180 180 179 176 169 185 196 202 204 203

Stand density index 379 276 297 297 289 280 268 308 334 344 343 338 327Canopy cover (percent) 65 53 54 53 51 49 47 59 61 61 60 58 56Crown competition factor 204 160 168 169 165 160 154 178 191 199 199 196 189Canopy base height (ft) 2 6 14 20 27 30 33 5 8 12 11 13 16

Canopy bulk density (kg/m3) 0.08 0.07 0.06 0.06 0.06 0.06 0.06 0.08 0.07 0.07 0.07 0.06 0.07

Prescribed fire Trees per acre 764 200 203 189 172 154 137 300 229 207 181 160 141

Quadratic mean diameter (in) 6.5 12.2 11.8 12.5 13.3 14.1 15.1 10.2 11.2 12.1 13.0 13.9 14.9Total volume (ft3) 5,287 4,938 5,199 5,571 5,920 6,082 6,316 4,978 5,272 5,592 5,865 6,046 6,276Merchantable volume (ft3) 4,494 4,347 4,633 4,924 5,320 5,439 5,670 4,360 4,669 4,914 5,244 5,389 5,637

Basal area (ft2) 174 163 153 161 167 167 171 169 158 164 167 168 171

Stand density index 379 276 263 270 273 268 266 308 276 279 276 270 267Canopy cover (percent) 65 53 46 46 46 45 44 59 49 48 47 46 45

Crown competition factor 204 160 138 143 145 144 145 178 147 150 150 148 147Canopy base height (ft) 2 10 15 24 28 31 7 7 12 19 25 29 32Canopy bulk density (kg/m3) 0.08 0.04 0.05 0.05 0.05 0.05 0.05 0.04 0.05 0.05 0.05 0.05 0.05

tpa = trees per acre; d.b.h. = diameter at breast height

Region 6 — Okanogan and Wenatchee National Forests 1

.
K

297

Table 25d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 96 10 4 6 65 9 35 0 0

10 9 66 10 34 9 36 6 35 10 29

20 10 68 9 32 10 36 9 33 6 31

30 10 86 9 14 10 54 6 25 9 21

40 10 99 12 1 10 71 6 18 9 11

50 10 92 12 8 10 88 6 8 9 4

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 65 6 34 2 1 6 51 10 48 9 2

10 6 83 10 17 0 0 6 71 10 21 9 8

20 6 90 10 10 0 0 6 67 10 22 9 11

30 6 93 10 7 0 0 6 61 10 25 9 13

40 9 93 10 7 0 0 6 52 10 37 9 11

`50 9 89 10 11 0 0 10 50 6 42 9 8

Pile and burn 1 6 97 2 3 0 0 6 97 9 3 0 0

10 6 100 0 0 0 0 6 90 9 10 0 0

20 6 100 0 0 0 0 6 86 9 14 0 0

30 9 100 0 0 0 0 6 75 9 13 10 12

40 9 100 0 0 0 0 6 61 10 27 9 12

50 9 97 10 3 0 0 6 49 10 43 9 8

Prescribed fire 1 6 88 2 12 0 0 6 100 0 0 0 0

10 9 100 0 0 0 0 6 100 0 0 0 0

20 9 100 0 0 0 0 6 88 10 12 0 0

30 9 97 10 3 0 0 6 78 10 21 9 1

40 9 85 10 15 0 0 9 71 10 29 0 0

50 9 70 10 30 0 0 9 58 10 42 0 0

Region 6 — Okanogan and Wenatchee National Forests 1
L

298

Region 6 — Okanogan and Wenatchee National Forests 1

Table 25f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 25e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 81 3 5 8 15 50 100Moderate—75th percentile 8 64 6 8 11 18 125 150Table 25d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 9 53 6 26 10 21 9 82 10 13 6 5

10 9 50 10 29 6 21 9 71 10 29 0 0

20 10 45 9 36 6 19 9 52 10 48 0 0

30 10 67 9 19 6 14 10 68 9 32 0

40 10 91 6 5 9 4 10 90 9 8 6 1

50 10 91 12 9 0 0 10 93 12 7 0 0

Pile and burn 1 9 67 6 33 0 0 9 94 6 6 0 0

10 9 70 6 29 10 1 9 97 10 3 0 0

20 9 49 10 26 6 25 9 71 10 29 0 0

30 10 51 9 28 6 21 10 52 9 48 0 0

40 10 76 6 13 9 11 10 72 9 25 6 2

50 10 99 6 1 0 10 93 9 5 6 1

Prescribed fire 1 6 83 9 17 0 0 6 71 9 29 0 0

10 6 57 9 24 10 19 6 43 9 33 10 24

20 6 49 10 29 9 22 6 37 10 36 9 27

30 10 47 6 37 9 15 10 56 6 27 9 16

40 10 62 6 29 9 9 10 75 6 17 9 8

50 10 80 6 16 9 4 10 94 6 5 9 2

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

299

Region 6 — Okanogan and Wenatchee National Forests 2

Site: Elevation = 4,800 ft, slope = 25 percent, aspect = 145°.Species (based on trees per acre): Douglas-fir (Pseudotsuga menziesii) = 99 percent, ponderosa pine (Pinus ponderosa) = 1 percent.

Stand attributes: Stem density = 2,514 tpa, basal area = 188 ft2/ac, top height = 86 ft, stand density index = 510, quadratic mean diameter = 3.7 in, crown competition factor = 369, canopy cover = 88 percent. 
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

300

Region 6 — Okanogan and Wenatchee National Forests 2
C

301

Region 6 — Okanogan and Wenatchee National Forests 2

Initial conditions/no-action trajectoryThis is a dense stand with 2,514 trees per acre (tpa) composed of primarily understory Douglas-fir with overstory ponderosa pine. Canopy base height is 7 ft and canopy bulk density is 0.52 kg/m3 (0.0325 lb/ft3), so initial conditions have low potential for passive crown fire but high potential for active crown fire spread (conditional crown fire) under severe fire weather. Potential tree mortality is 34 percent, and flame lengths are only 2 ft. Woody fuel loading is 11 tons/ac, and litter and duff loading is 12 tons/ac. With no action, canopy base height remains constant, canopy bulk density decreases, and flame lengths increase, so the potential for crown fire spread decreases, but the potential for passive crown fire increases. In 40 years, passive crown fire is predicted for severe fire weather, but surface fire is predicted for moderate fire weather. Surface fuels accumulate over time, and flame lengths are 6 ft in 50 years for severe fire weather.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment does not affect canopy base height, but fire-caused mortality of small trees reduces canopy bulk density and increases snag density. Surface fuel loading is greatly reduced and potential flame lengths decrease initially. All thinning treatments increase canopy base height and reduce canopy bulk density; the greater the thinning, the greater the change in forest structure. Immediately after the thinning the predicted fire type changes to surface fire for all treatments, but extensive activity fuels cause higher potential flame lengths. Both the pile and burn and the prescribed fire surface fuel treatments reduce woody fuels, and the prescribed fire treatment also reduces litter and duff, but potential flame lengths decrease only slightly because fuel model 5 is assigned to the open stands with low woody fuel loading. Flame lengths remain above 4 ft for severe fire weather, but are 2 ft or less for moderate fire weather. Brush fuels are not tracked in FFE and may or may not be present following treatment.

Silvicultural and surface fuel treatments—long-term effectsAll treatments reduce canopy bulk density sufficiently that active crown fire spread remains unlikely for the 50-year projection. In the prescribed fire only treatment, forest structure changes little over time, but surface fuels accumulate, and higher flame lengths cause a gradual increase in crown fire potential. In the 50 and 100 tpa treatments, regeneration causes an abrupt decline in canopy base height in 10 to 30 years depending on surface fuel treatment, but because flame lengths are low, the decline in canopy base height only temporarily increases crown fire potential. In the 200 and 300 tpa treatments, regeneration is minimal, so canopy base height continues to increase over time as the trees grow and the stand self­-thins. In high-density treatments with prescribed fire, regeneration is greater and canopy base height decreases in 40 years, at which time surface fuels have accumulated and flame lengths are higher, so passive crown fire is predicted again for severe fire weather. Another treatment would be necessary to reduce surface fuels or increase canopy base height. Crown fire potential remains low in all treatments for moderate fire weather for the entire 50-year projection.
D

302Table 26a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 14 14 12 10

3–6 in 4 0 8 9 8 66–12 in 4 2 2 3 3 4>12 in 0 0 0 0 0 0Litter 2 1 5 5 4 4Duff 10 7 7 8 9 10

Flame length (ft) Moderate 1 1 5 5 4 3

Severe 2 1 8 7 6 5

Torching index Severe 197 232 38 43 45 53Crowning index Severe 6 22 48 40 23 17Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Conditional Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 34 23 8 12 18 22

Severe 34 23 29 28 36 35

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 3 2

3–6 in 2 3 2 26–12 in 1 1 1 1>12 in 0 0 0 0Litter 5 4 4 4Duff 6 7 8 9

Flame length (ft) Moderate 2 2 2 1

Severe 6 5 4 2

Torching index Severe 50 62 138 447Crowning index Severe 48 40 23 17Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 8 12 18 22

Severe 10 18 18 22

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 2 2 2 26–12 in 1 2 2 2>12 in 0 0 0 0Litter 0 1 1 1Duff 5 6 6 7

Flame length (ft) Moderate 2 1 1 1

Severe 6 6 5 4

Torching index Severe 43 53 50 81Crowning index Severe 51 51 36 29Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 7 10 14 17

Severe 9 18 24 22

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Okanogan and Wenatchee National Forests 2
E

303

Table 26b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 6 8 10 10 10 1 7 5 5 6 6

3–6 in 4 4 5 6 7 8 0 6 6 6 6 76–12 in 4 3 4 4 6 7 2 3 3 4 5 6>12 in 0 1 2 3 5 6 0 1 2 4 6 7Litter 2 6 6 6 6 5 1 3 3 3 4 4Duff 10 10 11 12 12 13 7 7 8 8 9 9

Flame length (ft) Moderate 1 2 3 3 4 4 1 2 2 2 3 3

Severe 2 3 4 5 5 6 1 4 3 4 4 5

Torching index Severe 197 45 22 15 11 8 232 28 35 29 19 17Crowning index Severe 6 10 13 16 18 19 22 23 23 24 25 25Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Cond. Cond. Cond. Surface Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 159 295 474 353 314 229 536 18 39 59 70 74

18–29.9 in 4 4 5 5 5 5 5 5 5 6 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 14 8 5 4 3 3 14 8 5 4 4 4

3–6 in 8 8 7 7 7 7 9 8 8 8 7 76–12 in 2 2 3 3 4 4 3 3 3 3 4 5>12 in 0 1 2 3 5 7 0 1 2 3 5 6Litter 5 1 2 2 2 2 5 2 2 2 2 2Duff 7 7 8 8 8 8 8 8 9 9 9 9

Flame length (ft) Moderate 5 3 3 3 3 3 5 3 2 2 3 3

Severe 8 5 6 4 4 4 7 5 5 5 5 5

Torching index Severe 38 73 79 9 17 22 43 87 78 83 10 17Crowning index Severe 48 47 45 45 47 49 40 41 40 37 34 35Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 6 7 12 17 21 21 6 8 13 17 21 25

18–29.9 in 4 4 5 5 6 5 4 4 5 5 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 2
F

304Table 26b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 3 3 3 3 3 3 3 3 3 4

3–6 in 2 2 2 3 3 3 3 2 3 3 3 46–12 in 1 1 1 2 2 3 1 1 1 2 3 4>12 in 0 1 2 3 5 6 0 1 2 3 5 6Litter 5 1 2 2 2 2 4 2 2 2 2 2Duff 6 6 7 7 7 7 7 7 8 8 8 8

Flame length (ft) Moderate 2 2 4 2 2 2 2 1 2 2 2 2

Severe 6 6 6 3 3 4 5 5 5 5 5 4

Torching index Severe 50 51 65 16 23 26 62 70 72 86 11 38Crowning index Severe 48 47 45 45 46 40 40 39 39 36 33 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Passive Surface

Hard snags (stems/ac) 0–17.9 in 6 7 12 19 24 24 6 8 13 18 22 26

18–29.9 in 4 4 5 5 6 5 4 4 5 5 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 1 2 3 3 4 0 2 2 2 3 3

3–6 in 2 3 3 3 3 3 3 3 4 4 4 46–12 in 1 2 2 3 3 4 2 3 3 4 4 5>12 in 0 1 3 4 6 7 0 1 3 4 6 7Litter 0 1 2 2 2 2 4 2 2 2 2 2Duff 5 5 5 5 5 6 7 6 6 6 6 6

Flame length (ft) Moderate 2 2 2 2 2 2 1 1 2 2 2 2

Severe 6 3 3 3 3 4 6 6 5 3 4 4

Torching index Severe 43 4 17 24 31 35 53 61 67 31 18 19Crowning index Severe 51 50 33 24 22 20 51 49 47 42 40 40Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 10 10 15 24 32 34 16 10 14 18 23 27

18–29.9 in 5 5 5 5 5 5 5 5 5 5 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 2
G

305

Table 26b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 12 7 5 5 5 5 10 6 5 6 6 7

3–6 in 8 7 7 7 7 8 6 6 6 6 7 76–12 in 3 3 3 4 5 6 4 3 3 4 5 7>12 in 0 1 2 3 5 6 0 1 2 3 5 6Litter 4 3 3 3 3 3 4 3 3 4 4 4Duff 9 10 10 10 11 11 10 11 11 11 12 12

Flame length (ft) Moderate 4 3 2 2 3 3 3 2 2 2 3 3

Severe 6 4 4 4 4 5 5 4 3 4 4 5

Torching index Severe 45 95 120 124 111 96 53 120 147 128 102 87Crowning index Severe 23 25 26 26 26 26 17 20 19 20 21 21Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 4 7 14 22 29 33 7 13 25 37 48 54

18–29.9 in 4 4 5 5 5 5 4 4 5 5 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 3 3 3 4 5 5 2 3 4 5 6 7

3–6 in 2 2 3 3 3 4 2 2 2 3 4 56–12 in 1 1 1 2 3 5 1 1 1 2 4 6>12 in 0 1 2 3 5 6 0 1 2 3 5 6Litter 4 3 3 3 3 3 4 3 3 4 4 4Duff 8 9 9 9 9 10 9 9 10 10 10 11

Flame length (ft) Moderate 2 1 1 2 2 3 1 1 1 2 2 3

Severe 4 3 3 3 4 4 2 2 2 3 4 5

Torching index Severe 138 270 264 208 156 133 447 545 360 218 145 105Crowning index Severe 23 25 26 26 26 25 17 19 19 20 20 22Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 7 10 18 27 33 36 7 13 25 36 48 55

18–29.9 in 4 4 5 5 5 5 4 4 5 5 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 2
H

306

Table 26c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,514 2,182 1,773 1,532 1,277 1,126 544 534 505 461 411 361

Quadratic mean diameter (in) 3.7 4.1 4.6 5.1 5.7 6.1 3.7 6.9 7.5 8.1 8.8 9.5Total volume (ft 3) 4,651 5,145 5,504 5,977 6,340 6,818 4,049 4,273 4,691 5,049 5,435 5,805Merchantable volume (ft 3) 3,579 3,884 4,497 5,166 5,691 6,264 3,400 3,550 4,115 4,550 5,025 5,417Basal area (ft 2) 188 202 208 219 224 231 132 140 154 164 172 177Stand density index 510 525 517 522 513 514 284 297 317 327 332 331Canopy closure (percent) 88 88 86 85 83 82 63 65 67 67 66 65Crown competition factor 369 365 349 345 334 331 189 197 211 217 219 218Canopy base height (ft) 7 7 7 7 7 7 7 7 7 7 7 8Canopy bulk density (kg/m3) 0.52 0.31 0.25 0.18 0.16 0.15 0.12 0.12 0.12 0.11 0.11 0.10

Table 26b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 3 3 3 3 4 0 4 3 4 4 5

3–6 in 2 5 5 5 5 5 2 5 5 5 6 66–12 in 2 3 4 4 5 6 2 4 4 4 5 6>12 in 0 1 3 4 6 7 0 1 3 4 6 7Litter 1 2 2 2 2 2 1 2 2 3 3 3Duff 6 7 7 7 7 8 7 7 7 8 8 8

Flame length (ft) Moderate 1 2 2 2 2 3 1 2 2 2 3 3

Severe 5 5 5 5 4 4 4 4 4 4 4 5

Torching index Severe 50 69 76 86 13 23 81 88 90 92 14 11Crowning index Severe 36 37 38 38 35 33 29 31 30 32 32 31Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface Passive Passive

Hard snags (stems/ac) 0–17.9 in 29 11 16 21 25 29 43 12 20 26 33 36

18–29.9 in 5 5 5 5 5 5 5 5 5 6 5 530–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height; cond. = conditional.

Region 6 — Okanogan and Wenatchee National Forests 2
I

307

Table 26c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,514 50 148 144 136 127 118 100 147 142 135 127 118

Quadratic mean diameter (in) 3.7 18.0 10.7 11.1 11.7 12.3 13.1 13.8 11.8 12.3 12.9 13.7 14.4Total volume (ft3) 4,651 3,562 3,653 3,792 3,944 4,055 4,216 3,894 4,034 4,281 4,573 4,887 5,130Merchantable volume (ft3) 3,579 3,387 3,437 3,572 3,725 3,796 3,881 3,701 3,803 4,028 4,334 4,654 4,848Basal area (ft2) 188 89 93 96 101 105 110 103 111 117 123 129 133Stand density index 510 129 166 169 175 178 182 167 191 198 204 210 211Canopy cover (percent) 88 28 28 30 32 33 34 38 39 40 41 42 42Crown competition factor 369 86 89 92 100 103 106 110 117 121 127 133 135Canopy base height (ft) 7 31 35 40 5 8 10 28 32 32 33 6 8Canopy bulk density (kg/m3) 0.52 0.04 0.04 0.05 0.05 0.04 0.04 0.06 0.05 0.05 0.06 0.07 0.07

Pile and burn Trees per acre 2,514 50 148 144 136 127 118 100 173 168 160 151 140

Quadratic mean diameter (in) 3.7 18.0 10.7 11.1 11.7 12.3 13.1 13.8 10.8 11.3 11.9 12.6 13.3Total volume (ft3) 4,651 3,562 3,653 3,792 3,944 4,055 4,216 3,894 4,034 4,279 4,576 4,900 5,146Merchantable volume (ft3) 3,579 3,387 3,437 3,572 3,725 3,796 3,881 3,701 3,803 4,026 4,337 4,663 4,858Basal area (ft2) 188 89 93 96 101 105 110 103 111 117 123 130 135Stand density index 510 129 166 169 175 178 182 167 197 204 211 219 221Canopy cover (percent) 88 28 28 30 34 36 37 38 39 40 41 43 43Crown competition factor 369 86 89 92 100 103 106 110 117 121 128 135 138

Canopy base height (ft) 7 31 35 40 5 8 10 28 32 32 33 6 8Canopy bulk density (kg/m3) 0.52 0.04 0.04 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07

Prescribed fire Trees per acre 2,514 50 341 334 319 299 278 100 220 215 206 195 181

Quadratic mean diameter (in) 3.7 18.0 7.0 7.6 8.3 9.1 9.9 13.8 9.0 9.3 9.9 10.5 11.2Total volume (ft3) 4,651 3,361 3,438 3,624 3,836 4,203 4,524 3,560 3,665 3,838 4,074 4,300 4,517Merchantable volume (ft3) 3,579 3,187 3,230 3,338 3,470 3,619 4,075 3,375 3,452 3,600 3,835 4,041 4,192Basal area (ft2) 188 89 90 105 120 134 147 103 97 101 110 117 124Stand density index 510 129 190 214 237 255 271 167 186 191 202 211 217Canopy cover (percent) 88 28 33 41 47 50 52 38 33 34 38 40 42Crown competition factor 369 86 94 119 134 144 153 110 98 101 117 123 128

Canopy base height (ft) 7 42 2 4 7 10 13 29 32 33 4 7 9Canopy bulk density (kg/m3) 0.52 0.04 0.04 0.07 0.11 0.12 0.14 0.04 0.04 0.04 0.05 0.06 0.05

Region 6 — Okanogan and Wenatchee National Forests 2
J

308Table 26c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,514 200 220 211 197 181 166 300 317 301 278 250 221

Quadratic mean diameter (in) 3.7 10.6 10.7 11.4 12.1 13.0 13.7 9.2 9.5 10.2 11.0 11.8 12.6Total volume (ft3) 4,651 4,302 4,515 4,913 5,346 5,814 6,157 4,583 4,837 5,320 5,814 6,247 6,630Merchantable volume (ft3) 3,579 3,770 4,008 4,618 5,099 5,577 5,914 3,763 4,000 4,808 5,527 5,973 6,338Basal area (ft2) 188 124 137 149 158 166 171 139 157 172 183 189 192Stand density index 510 221 245 259 269 274 276 263 293 313 324 325 321Canopy cover (percent) 88 51 54 55 56 56 55 60 64 65 65 64 63Crown competition factor 369 148 161 172 179 183 186 179 198 212 220 221 219Canopy base height (ft) 7 23 26 27 29 31 35 19 22 24 26 29 32Canopy bulk density (kg/m3) 0.52 0.12 0.10 0.10 0.10 0.10 0.10 0.17 0.14 0.15 0.14 0.13 0.13

Pile and burn Trees per acre 2,514 200 233 224 209 193 176 300 330 314 291 262 230

Quadratic mean diameter (in) 3.7 10.6 10.4 11.0 11.8 12.6 13.4 9.2 9.3 10.0 10.7 11.5 12.4Total volume (ft3) 4,651 4,302 4,515 4,913 5,345 5,813 6,163 4,583 4,837 5,320 5,809 6,254 6,600Merchantable volume (ft3) 3,579 3,770 4,008 4,617 5,098 5,576 5,915 3,763 4,000 4,808 5,521 5,975 6,321Basal area (ft2) 188 124 137 149 158 166 171 139 157 172 183 189 191Stand density index 510 221 248 262 272 278 280 263 296 315 327 328 323Canopy cover (percent) 88 51 54 55 56 56 55 60 64 65 65 65 63Crown competition factor 369 148 161 172 179 183 186 179 198 212 220 222 218Canopy base height (ft) 7 23 26 27 29 31 35 19 22 24 26 29 32Canopy bulk density (kg/m3) 0.52 0.12 0.10 0.10 0.10 0.10 0.10 0.17 0.15 0.15 0.14 0.13 0.13

Prescribed fire Trees per acre 2,514 200 197 190 180 168 154 300 242 231 217 199 181

Quadratic mean diameter (in) 3.7 10.6 10.2 10.7 11.3 12.0 12.8 9.2 9.5 10.1 10.7 11.4 12.2Total volume (ft3) 4,651 3,777 3,925 4,184 4,480 4,808 5,091 3,908 4,072 4,370 4,687 5,014 5,298

Merchantable volume (ft3) 3,579 3,419 3,582 3,930 4,254 4,585 4,843 3,414 3,571 4,032 4,448 4,777 5,027Basal area (ft2) 188 124 111 118 125 132 138 139 120 129 136 142 146Stand density index 510 221 202 211 219 225 229 263 225 235 243 247 248Canopy cover (percent) 88 51 42 43 44 45 45 60 48 49 50 50 49

Crown competition factor 369 148 121 127 135 142 145 179 139 146 152 156 158

Canopy base height (ft) 7 24 26 27 29 6 8 19 23 23 25 6 6Canopy bulk density (kg/m3) 0.52 0.06 0.06 0.06 0.06 0.07 0.07 0.09 0.08 0.08 0.08 0.07 0.08

tpa = trees per acre; d.b.h. = diameter at breast height

Region 6 — Okanogan and Wenatchee National Forests 2

.
K

309

Table 26d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent

None 1 8 89 10 11 8 100 0 0

10 10 71 8 29 10 85 8 15

20 10 92 12 8 10 74 8 26

30 10 72 12 28 10 86 8 14

40 10 56 12 44 10 95 12 5

50 12 57 10 43 10 81 12 19

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 12 62 10 38 0 0 12 57 10 43 0 0

10 10 89 5 10 1 1110 10 95 5 5 0 0

20 10 60 6 40 0 10 68 5 32 0 0

30 10 53 9 47 0 0 10 65 5 34 8 2

40 10 60 9 40 0 0 10 74 5 24 8 2

`50 10 72 9 28 0 0 10 90 5 10 8 1

Pile and burn 1 5 56 10 38 1 6 5 67 10 33 0 0

10 5 92 1 8 0 0 5 98 10 2 0 0

20 6 98 2 2 10 1 5 92 10 8 0 0

30 9 89 10 11 0 0 5 74 10 20 8 6

40 9 73 10 27 0 0 5 55 10 37 8 8

50 9 57 10 43 0 0 10 57 8 43 0 0

Prescribed fire 1 5 77 1 23 0 0 5 100 0 0 0 0

10 9 100 0 0 0 0 5 99 10 1 0 0

20 9 98 10 2 0 0 5 87 10 13 0 0

30 9 78 10 22 0 0 8 72 10 28 0 0

40 9 56 10 44 0 0 9 56 10 44 0 0

50 10 66 9 34 0 0 10 63 9 37 0 0

Region 6 — Okanogan and Wenatchee National Forests 2
L

310

Region 6 — Okanogan and Wenatchee National Forests 2

Table 26f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 26e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 81 3 5 10 15 50 100Moderate—75th percentile 8 64 6 8 15 18 125 150Table 26d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 61 12 39 0 0 10 85 12 15 0 0

10 10 90 8 7 5 3 10 76 8 24 0 0

20 10 72 8 21 5 7 10 71 8 29 0 0

30 10 79 8 17 5 4 10 88 8 12 0 0

40 10 100 8 0 5 0 10 90 12 10 0 0

50 10 87 12 13 0 0 10 73 12 27 0 0

Pile and burn 1 8 45 5 35 10 21 8 92 10 8 0 0

10 8 65 5 29 10 6 8 92 10 8 0 0

20 8 64 5 20 10 16 8 75 10 25 0 0

30 8 51 10 36 5 13 10 52 8 48 0 0

40 10 62 8 30 5 8 10 86 8 14 0 0

50 10 92 8 6 5 2 10 88 12 12 0 0

Prescribed fire 1 5 100 0 0 0 0 5 74 8 26 0 0

10 5 71 10 22 8 7 10 39 5 37 8 24

20 5 59 10 31 8 10 10 45 5 30 8 25

30 10 46 5 43 8 12 10 62 5 20 8 18

40 10 64 5 26 8 9 10 84 5 8 8 8

50 10 86 8 14 0 0 10 95 12 5 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Initial stand conditions

A

311

Site: Elevation = 3,400 ft, slope = 36 percent, aspect = 266°.Species (based on trees per acre): Grand fir (Abies grandis) = 53 percent, Douglas-fir (Pseudotsuga menziesii) = 38 percent, lodgepole pine (Pinus contorta) = 1 percent, ponderosa pine (Pinus ponderosa) = 8 percent. 

Stand attributes: Stem density = 2,092 tpa, basal area = 166 ft2/ac, top height = 92 ft, stand density index = 445, quadratic mean diameter = 3.8 in, crown competition factor = 217, canopy cover = 66 percent. 

Region 6 — Okanogan and Wenatchee National Forests 3
Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

B

312

Region 6 — Okanogan and Wenatchee National Forests 3
C

313

Region 6 — Okanogan and Wenatchee National Forests 3

Initial conditions/no-action trajectoryThis is a dense stand with 2,092 trees per acre (tpa) composed of grand fir, Douglas-fir, lodgepole pine, and ponderosa pine. Canopy base height is 2 ft, and canopy bulk density is 0.08 kg/m3 (0.005 lb/ft3) so initial conditions have high potential for passive crown fire and tree mortality, but low potential for active crown fire spread under severe fire weather. Initial woody fuel loading is 9 tons/ac, and litter and duff loading is 7 tons/ac. With no action, canopy base height will increase and canopy bulk density will decrease over time as trees grow and the stand self-thins, but surface fuels accumulate and potential flame lengths increase, so crown fire potential remains similar. Passive crown fire is predicted for the entire 50-year trajectory for severe fire weather, but surface fire is predicted for moderate fire weather.

Silvicultural and surface fuel treatments—immediate effectsThe prescribed fire only treatment increases canopy base height and reduces canopy bulk density and surface fuels enough to change the predicted fire type to surface fire for severe and moderate fire weather; however, many snags are created and surface fuels accumulate rapidly. Potential flame lengths increase immediately after treatment despite the reduction in woody surface fuels, because the more open stand is characterized by fuel model 6 suggesting that brush fuels are an important contributor to fire behavior following prescribed fire; this may or may not be a factor, depending on the site. All thinning treatments effectively reduce canopy bulk density and increase canopy base height enough to reduce crown fire potential and tree mortality, but the 100 to 300 tpa treatments similarly affect stand structure. The thinning treatments also increase surface fuels and potential flame lengths; the greater the thinning, the greater the change in surface fuels and flame lengths. These activity fuels are reduced by the pile and burn treatment and to a greater extent by prescribed fire, but this change in surface fuels does not reduce flame lengths, because the more open stands with low surface fuels are characterized by fuel model 6. The 300 tpa treatment with a prescribed burn surface fuel treatment is still predicted to be passive crown fire immediately after treatment because canopy base height is relatively low and fuel model 6 is the primary model used. Brush fuels are not tracked in FFE, so these results should be interpreted with caution.

Silvicultural and surface fuel treatments—long-term effectsCrown fire potential decreases over time in the prescribed fire only treatment as canopy base height continues to increase, but surface fuels accumulate and flame lengths are predicted to be 5 ft in 50 years. Regeneration in the 50 tpa treatment causes an abrupt decline in canopy base height, and passive crown fire becomes likely again in 30 years. At this time, a second treatment would be necessary to prevent passive crown fire. Regeneration plays an important role in crown fire potential over time, but the decrease in canopy base height may not be as extreme or abrupt in reality. Canopy base height continues to increase in all other thinning treatments, so crown fire potential remains low for both moderate and severe fire weather for the entire 50-year projection.
D

314Table 27a—Projected treatment effects on fuels and fire first cycle after treatments implemented

Surface fuel treatment Fuel/fire attribute

Initial 

condition

Prescribed 

fire only

Thin from 

below to 50 tpa, 

18-in d.b.h. limit

Thin from 

below to 100 tpa, 

18-in d.b.h. limit

Thin from 

below to 200 tpa, 

18-in d.b.h. limit

Thin from 

below to 300 tpa, 

18-in d.b.h. limit

None Surface fuel loadings (tons/ac) 0–3 in 3 1 7 6 5 4

3–6 in 3 0 4 5 3 36–12 in 3 1 1 2 2 2>12 in 0 0 0 0 0 0Litter 2 1 4 3 3 3Duff 5 4 2 4 4 5

Flame length (ft) Moderate 2 4 4 4 3 2

Severe 3 5 6 5 4 3

Torching index Severe 0 19 63 22 26 34Crowning index Severe 31 43 53 40 34 31Type of fire Moderate Surface Surface Surface Surface Surface Surface

Severe Passive Surface Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 21 16 7 11 16 19

Severe 75 30 11 25 26 23

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 1 1

3–6 in 1 1 1 16–12 in 0 1 1 1>12 in 0 0 0 0Litter 3 3 3 3Duff 2 3 4 4

Flame length (ft) Moderate 4 4 3 2

Severe 7 6 4 3

Torching index Severe 41 18 26 37Crowning index Severe 53 40 34 31Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Surface

Potential basal area mortality (%) Moderate 7 12 16 19

Severe 24 31 25 21

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 0 0 0

3–6 in 1 1 1 16–12 in 1 1 1 1>12 in 0 0 0 0Litter 1 1 1 1Duff 2 3 3 3

Flame length (ft) Moderate 4 4 4 3

Severe 7 6 6 8

Torching index Severe 31 22 22 7Crowning index Severe 56 43 42 42Type of fire Moderate Surface Surface Surface Surface

Severe Surface Surface Surface Passive

Potential basal area mortality (%) Moderate 7 11 15 16

Severe 23 31 32 56

tpa = trees per acre, d.b.h. = diameter at breast height. 

Region 6 — Okanogan and Wenatchee National Forests 3
E

315

Table 27b—Treatment effect on fuels and fire behavior, 50-year projectionSurface fuel treatment

No action Prescribed fire only

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 3 6 9 10 9 8 1 5 6 6 7 7

3–6 in 3 3 5 6 7 8 0 4 4 4 5 56–12 in 3 3 4 6 8 9 1 4 4 4 5 5>12 in 0 0 1 2 4 6 0 1 1 2 3 4Litter 2 4 4 3 3 3 1 3 3 3 3 3Duff 5 5 6 6 7 7 4 4 4 5 5 5

Flame length (ft) Moderate 2 2 3 4 4 4 4 3 3 3 3 3

Severe 3 4 4 5 6 6 5 5 4 4 4 5

Torching index Severe 0 8 5 5 7 9 19 41 49 102 132 155Crowning index Severe 31 33 36 36 36 37 43 40 36 35 35 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Passive Passive Passive Passive Passive Passive Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 189 407 395 229 166 127 520 9 11 21 21 20

18–29.9 in 1 2 3 4 4 4 1 1 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 7 5 4 3 4 4 6 5 5 5 6 6

3–6 in 4 4 4 4 4 5 5 4 5 5 5 66–12 in 1 1 1 1 1 1 2 2 2 2 2 3>12 in 0 0 0 0 0 1 0 0 0 0 1 2Litter 4 2 2 2 3 3 3 3 3 3 3 3Duff 2 3 3 3 4 4 4 4 4 5 5 5

Flame length (ft) Moderate 4 4 4 4 4 2 4 3 3 3 3 3

Severe 6 6 6 6 6 4 5 5 5 5 5 5

Torching index Severe 63 82 103 0 7 22 22 60 99 124 145 177Crowning index Severe 53 51 50 50 49 48 40 37 35 34 35 35Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Passive Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 1 3 3 3 4 1 2 4 10 17 18

18–29.9 in 0 0 0 0 1 1 0 0 0 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 3
F

316Table 27b—Treatment effect on fuels and fire behavior, 50-year projection (continued)

Surface fuel treatment

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 2 2 3 3 4 4 2 3 4 5 6 6

3–6 in 1 1 2 2 3 3 1 2 2 3 3 46–12 in 0 0 1 1 1 1 1 1 1 1 1 2>12 in 0 0 0 0 0 1 0 0 0 0 1 2Litter 3 2 2 2 3 3 3 3 3 3 3 3Duff 2 2 3 3 3 4 3 4 4 4 5 5

Flame length (ft) Moderate 4 4 4 4 2 2 4 4 3 3 3 3

Severe 7 7 7 6 3 4 6 5 5 5 5 5

Torching index Severe 41 62 78 0 21 21 18 55 88 117 138 162Crowning index Severe 53 51 50 50 49 49 40 37 34 34 35 35Type of fire Moderate Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 1 4 4 4 9 1 2 3 15 18 19

18–29.9 in 0 0 0 0 1 1 0 0 0 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 2 2 3 3 4 0 3 3 4 5 5

3–6 in 1 2 2 2 3 4 1 2 3 3 4 46–12 in 1 1 2 2 2 2 1 3 4 4 4 4>12 in 0 1 1 1 2 2 0 1 1 2 2 3Litter 1 2 2 2 3 3 3 2 3 3 3 3Duff 2 2 2 2 3 3 3 3 3 3 4 4

Flame length (ft) Moderate 4 4 4 2 2 2 4 4 4 3 3 3

Severe 7 7 7 3 3 4 6 6 6 5 5 5

Torching index Severe 31 51 77 12 18 19 22 52 92 116 132 5Crowning index Severe 56 54 54 44 35 33 43 40 38 37 38 38Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Passive Surface Surface Surface Surface Surface Surface Surface Passive

Hard snags (stems/ac) 0–17.9 in 9 8 8 7 12 18 16 9 7 10 17 20

18–29.9 in 1 1 1 0 1 1 1 1 1 1 1 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 3
G

317

Table 27b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Surface fuel loadings (tons/ac) 0–3 in 5 5 7 7 7 8 4 5 8 9 9 9

3–6 in 3 3 4 5 5 6 3 3 4 5 6 76–12 in 2 2 2 3 4 5 2 2 3 4 5 7>12 in 0 0 0 1 2 3 0 0 0 1 2 4Litter 3 3 3 3 3 3 3 4 3 4 4 4Duff 4 5 5 6 6 7 5 5 6 6 7 7

Flame length (ft) Moderate 3 3 3 3 3 3 2 2 3 3 3 4

Severe 4 4 4 4 4 5 3 3 4 4 5 5

Torching index Severe 26 72 102 123 150 150 34 56 66 121 118 103Crowning index Severe 34 35 33 32 32 32 31 35 33 32 34 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 10 21 23 23 35 11 26 37 30 46 59

18–29.9 in 0 0 1 1 1 3 0 0 1 1 1 430–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Pile and burn Surface fuel loadings (tons/ac) 0–3 in 1 3 6 7 7 8 1 4 7 8 8 9

3–6 in 1 1 2 3 4 5 1 1 2 4 4 66–12 in 1 1 1 2 3 4 1 1 1 2 3 6>12 in 0 0 0 1 2 3 0 0 0 1 2 4Litter 3 3 3 3 3 3 3 4 3 4 4 4Duff 4 4 5 5 6 6 4 5 5 6 6 7

Flame length (ft) Moderate 3 2 3 3 3 3 2 2 3 3 3 4

Severe 4 4 4 4 4 4 3 3 4 4 4 5

Torching index Severe 26 70 100 119 142 174 37 71 67 114 139 107Crowning index Severe 34 35 33 32 32 30 31 35 33 32 33 34Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 1 10 22 23 22 36 11 26 36 29 49 68

18–29.9 in 0 0 1 1 1 3 0 0 1 1 2 230–36 in 0 0 0 0 0 0 0 0 0 0 0 0

Region 6 — Okanogan and Wenatchee National Forests 3
H

318

Table 27c—Treatment effect on forest stand attributes, 50-year trajectorySurface fuel treatment Stand attribute

No action Prescribed fire only

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,092 1,630 1,318 1,139 984 876 194 193 187 172 162 153

Quadratic mean diameter (in) 3.8 4.5 5.1 5.7 6.2 6.7 3.8 12.2 13.3 14.4 15.4 16.5Total volume (ft 3) 4,896 5,758 6,373 7,074 7,695 8,232 4,759 5,312 6,395 7,266 8,168 9,043Merchantable volume (ft 3) 4,328 5,236 5,887 6,689 7,290 7,841 4,379 4,967 6,012 6,922 7,752 8,607

Basal area (ft 2) 166 181 188 199 206 212 144 157 180 196 211 226Stand density index 445 454 449 456 456 457 248 265 295 310 326 341Canopy closure (percent) 66 66 65 62 62 61 49 51 54 56 57 58

Crown competition factor 217 217 214 218 219 220 145 158 179 191 203 215

Canopy base height (ft) 2 4 5 6 7 8 10 16 17 31 36 41Canopy bulk density (kg/m3) 0.08 0.07 0.07 0.07 0.07 0.06 0.05 0.06 0.07 0.07 0.07 0.07

Table 27b—Treatment effect on fuels and fire behavior, 50-year projection (continued)Surface fuel treatment

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

Fuel/fire attribute 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

Prescribed fire Surface fuel loadings (tons/ac) 0–3 in 0 4 4 5 6 6 0 4 5 6 6 7

3–6 in 1 3 4 4 5 6 1 4 4 5 5 66–12 in 1 4 4 4 5 5 1 4 4 5 5 6>12 in 0 1 1 2 2 3 0 1 1 2 3 4Litter 1 3 3 3 3 3 1 3 3 3 3 3Duff 3 3 4 4 5 5 3 4 4 4 5 5

Flame length (ft) Moderate 4 3 3 3 3 3 3 3 3 3 4 4

Severe 6 5 5 5 4 5 8 4 4 4 5 6

Torching index Severe 22 46 80 101 132 170 7 26 52 96 93 101Crowning index Severe 42 39 36 35 35 35 42 38 36 36 36 36

Type of fire Moderate Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface Surface

Severe Surface Surface Surface Surface Surface Surface Passive Surface Surface Surface Surface Surface

Hard snags (stems/ac) 0–17.9 in 30 9 10 20 22 20 48 9 17 25 23 21

18–29.9 in 1 1 1 1 2 2 1 1 1 1 1 130–36 in 0 0 0 0 0 0 0 0 0 0 0 0

tpa = trees per acre; d.b.h. = diameter at breast height.

Region 6 — Okanogan and Wenatchee National Forests 3
I

319

Table 27c—Treatment effect on forest stand attributes, 50-year trajectory (continued)Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 50 tpa, 18-in d.b.h. limit Thin from below to 100 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,092 50 149 147 145 142 140 100 149 147 141 133 125

Quadratic mean diameter (in) 3.8 19.3 11.9 12.7 13.6 14.3 15.1 15.5 13.8 14.8 15.8 16.8 17.9Total volume (ft3) 4,896 4,120 4,516 5,294 6,169 6,944 7,786 4,980 5,554 6,658 7,629 8,463 9,317

Merchantable volume (ft3) 4,328 3,955 4,355 5,076 5,961 6,679 7,506 4,741 5,362 6,378 7,378 8,161 9,014

Basal area (ft2) 166 102 116 130 146 159 173 131 155 177 193 205 219Stand density index 445 144 198 216 237 253 270 202 250 277 295 306 319

Canopy cover (percent) 66 29 31 33 37 39 40 42 46 49 50 51 51Crown competition factor 217 84 95 105 120 133 144 124 146 164 177 186 196Canopy base height (ft) 2 31 38 44 4 6 8 11 25 39 47 51 56Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.04 0.04 0.04 0.04 0.06 0.06 0.07 0.07 0.07 0.07

Pile and burn Trees per acre 2,092 50 199 196 193 190 183 100 175 173 162 153 144

Quadratic mean diameter (in) 3.8 19.3 10.3 11.0 11.8 12.4 13.1 15.5 12.7 13.7 14.7 15.6 16.6Total volume (ft3) 4,896 4,120 4,516 5,293 6,166 6,935 7,697 4,980 5,554 6,657 7,534 8,418 9,238

Merchantable volume (ft3) 4,328 3,955 4,355 5,076 5,960 6,665 7,417 4,741 5,362 6,378 7,287 8,118 8,926Basal area (ft2) 166 102 116 130 146 159 172 131 155 177 191 204 217Stand density index 445 144 210 229 251 268 283 202 259 286 300 313 326

Canopy cover (percent) 66 29 31 34 37 40 41 42 46 49 50 50 51Crown competition factor 217 84 95 105 121 137 146 124 146 164 175 185 195

Canopy base height (ft) 2 31 38 44 4 6 7 11 25 38 47 52 56Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.04 0.04 0.04 0.04 0.06 0.06 0.07 0.07 0.07 0.07

Prescribed fire Trees per acre 2,092 50 344 339 334 324 310 100 230 227 221 208 195

Quadratic mean diameter (in) 3.8 19.3 7.6 8.1 8.7 9.2 9.7 15.5 10.4 11.2 11.9 12.8 13.6Total volume (ft3) 4,896 3,834 4,199 4,920 5,733 6,429 7,057 4,467 4,968 5,942 6,851 7,701 8,470Merchantable volume (ft3) 4,328 3,678 4,047 4,715 5,533 6,166 6,770 4,258 4,794 5,697 6,620 7,406 8,196Basal area (ft2) 166 102 108 120 136 149 159 131 136 155 171 184 197Stand density index 445 144 220 240 265 282 295 202 246 272 292 307 319Canopy cover (percent) 66 29 29 33 39 42 43 42 40 43 45 47 48Crown competition factor 217 84 87 98 122 138 146 124 124 140 153 164 174

Canopy base height (ft) 2 31 39 44 4 6 8 15 23 37 46 50 4Canopy bulk density (kg/m3) 0.08 0.04 0.04 0.04 0.05 0.07 0.08 0.05 0.06 0.06 0.06 0.06 0.06

Region 6 — Okanogan and Wenatchee National Forests 3
J

320Table 27c—Treatment effect on forest stand attributes, 50-year trajectory (continued)

Surface fuel treatment Stand attribute

Initial 

condition

Thin from below to 200 tpa, 18-in d.b.h. limit Thin from below to 300 tpa, 18-in d.b.h. limit

1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 1 yr 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs

None Trees per acre 2,092 200 217 202 190 179 161 300 300 273 255 226 185

Quadratic mean diameter (in) 3.8 11.8 12.4 13.5 14.6 15.6 16.7 9.9 10.8 11.9 13.0 14.1 15.5Total volume (ft3) 4,896 5,462 6,036 7,097 8,148 9,149 9,704 5,508 6,093 7,188 8,307 9,083 9,373Merchantable volume (ft3) 4,328 4,968 5,637 6,702 7,768 8,703 9,266 4,902 5,536 6,609 7,874 8,605 8,931Basal area (ft2) 166 151 181 202 221 238 243 159 189 212 235 245 244Stand density index 445 260 305 328 348 366 364 293 337 363 388 391 376Canopy cover (percent) 66 53 57 58 60 61 60 58 62 64 66 65 64Crown competition factor 217 157 184 201 216 230 234 176 203 222 242 245 244Canopy base height (ft) 2 11 24 30 33 37 42 10 14 17 27 31 37Canopy bulk density (kg/m3) 0.08 0.07 0.07 0.07 0.08 0.08 0.08 0.08 0.07 0.07 0.08 0.07 0.07

Pile and burn Trees per acre 2,092 200 230 213 200 189 169 300 313 286 267 234 198

Quadratic mean diameter (in) 3.8 11.8 12.0 13.2 14.2 15.2 16.2 9.9 10.5 11.7 12.7 13.8 15.0Total volume (ft3) 4,896 5,462 6,036 7,093 8,142 9,147 9,722 5,508 6,093 7,205 8,322 9,067 9,531Merchantable volume (ft3) 4,328 4,968 5,637 6,700 7,762 8,699 9,286 4,902 5,536 6,623 7,890 8,593 9,085Basal area (ft2) 166 151 181 202 220 237 243 159 189 213 236 245 244Stand density index 445 260 308 332 352 369 368 293 340 367 393 395 381Canopy cover (percent) 66 53 57 58 60 61 60 58 62 64 66 65 62Crown competition factor 217 157 184 201 215 230 234 176 203 223 243 248 237

Canopy base height (ft) 2 11 24 30 33 37 42 10 14 17 27 31 35Canopy bulk density (kg/m3) 0.08 0.07 0.07 0.07 0.08 0.08 0.08 0.08 0.07 0.07 0.08 0.07 0.07

Prescribed fire Trees per acre 2,092 200 203 198 183 172 163 300 236 224 206 195 183

Quadratic mean diameter (in) 3.8 11.8 11.7 12.7 13.7 14.7 15.6 9.9 11.0 12.0 13.1 14.0 15.0Total volume (ft3) 4,896 4,708 5,269 6,365 7,253 8,143 9,004 4,754 5,322 6,326 7,238 8,190 9,129

Merchantable volume (ft3) 4,328 4,380 5,005 6,051 6,940 7,759 8,641 4,380 4,986 5,928 6,895 7,786 8,756Basal area (ft2) 166 151 151 174 189 204 217 159 156 177 193 209 226Stand density index 445 260 261 291 305 320 334 293 275 301 318 336 353Canopy cover (percent) 66 53 47 50 51 52 53 58 50 53 54 55 57Crown competition factor 217 157 146 165 176 188 198 176 155 173 186 199 212Canopy base height (ft) 2 12 20 31 35 40 46 10 17 22 27 31 36Canopy bulk density (kg/m3) 0.08 0.05 0.06 0.07 0.07 0.07 0.07 0.05 0.06 0.07 0.07 0.07 0.07

tpa = trees per acre; d.b.h. = diameter at breast height

Region 6 — Okanogan and Wenatchee National Forests 3

.
K

321

Table 27d—Forest Vegetation Simulator fuel model selectionSurface fuel treatment Years

No action Prescribed fire only

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent

None 1 9 96 10 4 6 68 9 32 0 0

10 10 52 9 48 10 51 9 28 6 21

20 10 97 12 3 10 57 9 31 6 12

30 10 75 12 25 10 74 9 20 6 6

40 10 65 12 35 10 90 9 9 6 2

50 10 60 12 40 10 98 12 2 0 0

Surface fuel treatment Years

Thin from below to 50 tpa, 18-in. d.b.h. limit Thin from below to 100 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 10 77 6 21 2 1 10 61 6 35 9 5

10 6 70 10 30 0 0 6 44 10 38 9 18

20 6 78 10 22 0 0 10 42 6 33 9 25

30 6 82 10 18 0 0 10 48 9 26 6 26

40 6 76 10 24 0 0 10 61 9 21 6 18

`50 9 65 10 35 0 0 10 78 9 13 6 9

Pile and burn 1 6 95 2 5 0 0 6 88 9 12 0 0

10 6 100 0 0 0 0 6 70 9 30 0 0

20 6 100 0 0 0 0 6 48 9 37 10 15

30 6 99 10 1 0 0 6 34 10 33 9 33

40 9 89 10 11 0 0 10 47 9 28 6 25

50 9 74 10 26 0 0 10 63 9 21 6 16

Prescribed fire 1 6 83 2 17 0 0 6 100 0 0 0 0

10 6 93 2 7 0 0 6 89 10 9 9 2

20 6 100 0 0 0 0 6 61 10 27 9 12

30 9 92 10 8 0 0 6 45 10 38 9 17

40 9 80 10 20 0 0 10 54 6 30 9 14

50 9 65 10 35 0 0 10 69 6 19 9 12

Region 6 — Okanogan and Wenatchee National Forests 3
L

322

Region 6 — Okanogan and Wenatchee National Forests 3

Table 27f—Prescribed fire weather conditions used in modelsWindspeed (mph) 10Moisture category* 3 = Moist

Temperature (°F) 70

*Moisture categories correspond to variant-specific percentage Table 27e—FVS fuel model selectionmoisture values from Reinhardt and Crookston (2003).

Fuel moisture

Fire weather conditions Windspeed Temperature 1-hr (0–0.25 in) 10-hr (0.25–1 in) 100-hr (1–3 in) 1,000-hr (3+ in) Duff Live

Miles/hour °F - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Severe—98th percentile 14 81 3 5 8 15 50 100Moderate—75th percentile 8 61 6 8 11 18 125 150Table 27d—Forest Vegetation Simulator fuel model selection (continued)Surface fuel treatment Years

Thin from below to 200 tpa, 18-in. d.b.h. limit Thin from below to 300 tpa, 18-in. d.b.h. limit

Fuel models Fuel models

Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight Model Weight

Percent Percent Percent Percent Percent Percent

None 1 9 44 10 31 6 26 9 73 10 19 6 7

10 9 55 10 34 6 11 9 60 10 40 0 0

20 10 58 9 39 6 3 10 75 9 25 0 0

30 10 78 9 22 0 10 99 9 1 0 0

40 10 93 9 7 0 0 10 92 12 8 0 0

50 10 93 12 7 0 0 10 75 12 25 0 0

Pile and burn 1 9 63 6 37 0 0 9 91 6 9 0 0

10 9 80 6 16 10 3 9 88 10 12 0 0

20 9 57 10 38 6 5 10 54 9 46 0 0

30 10 62 9 37 6 1 10 81 9 19 0 0

40 10 77 9 23 0 0 10 98 9 2 0 0

50 10 98 9 2 0 0 10 78 12 22 0 0

Prescribed fire 1 6 85 9 15 0 0 6 60 9 40 0 0

10 6 45 10 30 9 25 9 41 10 32 6 27

20 10 45 9 28 6 27 10 66 9 23 6 11

30 10 66 9 19 6 15 10 99 9 1 0

40 10 85 9 9 6 6 10 84 12 16 0 0

50 10 100 12 0 0 0 10 67 12 33 0 0

tpa = trees per acre, d.b.h. = diameter at breast height.
Pacific Northwest Research Station

Web site http://www.fs.fed.us/pnw

Telephone (503) 808-2592

Publication requests (503) 808-2138

FAX (503) 808-2130

E-mail pnw_pnwpubs@fs.fed.us

Mailing address Publications Distribution

Pacific Northwest Research Station

 P.O. Box 3890

 Portland, OR 97208-3890