# Presentation: 777529

## Interpreting Fire Behavior

- National Interagency Fuels Technology Team

## Objectives

- Review of applications of surface & canopy fuel characteristics
- Relate fuel characteristics to fire behavior interpretations
- Understand and apply characteristics of surface, crown, and torching fire behavior
- Assess differences in fire behavior fuel model 13 system for treatment design
- Conduct logical checks on fire behavior and FRCC input data to assure consistency

## Fire Behavior

-   Fire Behavior Fuel model (FBFM) – surface fire
- 	- 13 – Anderson
-    - 40 – Scott & Burgan
- 	- custom fuel models
-   Canopy cover (CC) – wind, fuel moisture
-   Canopy height (CH) – torching/spotting
-   Canopy base height (CBH) – crown fire transition
-   Canopy bulk density (CBD) – crown fire spread
-   Canopy foliar moisture – crown fire spread
-   Existing vegetation type (EVT) – torching/spotting

**Notes:**
As you design treatment strategies it is important to focus your treatment effects on data characteristics at the ones that will change the objective.  This is illustrated with the following examples:
Fire behavior fuel model – change if want to change surface rate of spread or flame length; as a treatment process you can reduce trees and shrubs but you can’t increase because you must grow them over time; you can increase grass and down wood within a treatment year; usually you can only reduce litter and duff.
 Canopy cover- as a treatment process you can usually only reduce tree canopy cover; reduced canopy cover increases mid-flame wind speed, which may not be desirable in some cases; reduced canopy cover decreases fuel moisture, which may not be desirable in some cases; reduced canopy cover reduces tree canopy bulk density, which is usually desirable; reducing canopy cove may be correlated with increasing canopy base height; reducing tree canopy cover usually increases surface grass and shrub vegetation cover and surface fuels; reduced canopy cover may indicate need to change the fuel model; reducing canopy cover without use of prescribed fire usually increases surface litter.
Canopy height – as a treatment process you can usually only reduce tree canopy height; reduced height can reduce potential for torching and spotting; if you reduce height you may be reducing canopy cover; if you reduce height you may be reducing canopy bulk density.
Canopy base height – as a treatment process you can usually only increase tree canopy base height; increasing canopy base height decreases the probability of a surface to crown fire transition; in general a surface fire will not transition to a crown fire if the canopy base height is 2-3 times the longer than the flame length; if canopy base height increases it is usually correlated with a decrease in canopy bulk density; if canopy base height is increased it may be correlated with a decrease in tree canopy cover.
Canopy bulk density – as a treatment process you can usually only decrease the tree canopy bulk density; decreasing canopy bulk density decreases the probability of a passive to active crown fire spread, which is usually desirable; a passive crown fire will not transition to an active crown fire if the canopy bulk density is less than .05 kg/m3 and is unlikely for most types with .1 kg/m3 or less; a reduction in canopy bulk density is usually associated with a reduction in canopy cover and increase in canopy base height.
Existing vegetation type – used to infer the tree species that would produce torching and spotting; usually short needle and shade tolerant types produce higher probability of torching and spotting.  The existing vegetation cover, height, and succession class associated with the type are different themes than the tree canopy cover and height themes.  These themes are not tree specific.  Existing vegetation cover refers to the cover of the upper  lifeform of the vegetation type.  Existing vegetation height refers to the average height of the upper lifeform of the vegetation type.  Successional class is an assignment to 1 of 6 classes based on the combination of type, canopy cover, and height.  In many cases these  3 themes may need to be changed to make logical sense with changes in the other fuel and vegetation characteristics.

## Fuel Model

- Fuel loading - dead
- 1 hour (0-1/4 in), 10 hour (1/4-1 in), 100 hour (1-3 in)
- Fuel loading – live
- Live herbaceous, live woody
- Surface-to-volume ratio (1/cubic volume)
- Fuel bed depth
- Moisture of extinction - %
- Heat content – live & dead fuels
**Used to predict surface fire behavior**

**Notes:**
For those that need a more in depth review of surface fuel models they are used to characterize the dead and live fuel loading with associated moisture of extinction and heat content.  These inputs provide the information to predict surface fire behavior characteristics, such as rate of spread (ROS) and flame length (FL).

## Fuel Model

- 10- timber with dead down fuels

**Notes:**
This is an example of fuel model 10 in the Anderson 13 model system.  Fuel model 10 is characterized by heavy large and fine woody fuel loading.

## Canopy Characteristics

- Canopy cover
- Canopy height
- Canopy base height
- Canopy bulk density
- Foliar moisture

**Notes:**
The following information provides a more in depth review of tree canopy characteristics.

## Canopy Cover

- Used to predict shading – effects foliar moisture content (more cover = higher moisture = reduced surface fire behavior)
- Used for adjusting wind reduction factor – (more cover = higher wind reduction = reduced surface fire behavior)

**Notes:**
Canopy cover effects shading which effects fuel moisture and wind speed.

## Canopy Cover

**Notes:**
This is a landscape of pinyon-juniper with 40-60% canopy cover.

## Canopy Height

- Used in predicting embers
- Used in wind reduction factor
- Used in volume of crown fuels

**Notes:**
Tree canopy height is used for predicting ember amount and lofting for estimates of torching and spotting.  Height is also used in adjusting the wind reduction and in estimating total volume of crown fuels.

## Canopy Height

## Canopy Base Height

- Height to the base of the live canopy
- Incorporates ladder fuels (dead branches, lichen, regeneration)
- Average lowest height above the ground to propagate a fire vertically through the canopy

## Canopy Base Height

**1 meter**

**4 meters**

## Canopy Base Height

## Canopy Base Height

## Canopy Bulk Density

- Estimate of canopy fuels consumed in the flaming front of an active crown fire
- “Effective” CBD – from plot characteristics
- Does not assume uniform tree distribution
- Maximum 4.5 m (15 ft) running mean
- Same as used for FVS-FFE
- Stereo photo guide to adjust – Scott & Reinhardt (2005)

## Canopy Bulk Density

- Tree species (higher for short needle & shade tolerant)

**.06 kg/cu-m**

**.20 kg/cu-m**

**.01 kg/cu-m**

## Foliar Moisture

- Short needle shade tolerant, fire intolerant species – 75-100% in dry conditions
- Long needle shade intolerant, fire tolerant species – 100 – 150% in dry conditions
- Default of 100%

## Foliar Moisture

-  Opening the canopy can reduce foliar moisture
-  Short needle, fire intolerant species reduce foliar moisture

## Fire Behavior

- Function of surface fire spread
- Transition to crown fire
- Crown fire spread – conditional, passive, active

## Surface Fire

- Some basic “rules of thumb” to help in design

## Surface Fire

- Fireline intensity – heat release in flaming front
-  function (fuel heat per unit area, rate of spread, moisture/temperature)
- Rate of spread – rate of movement of flaming front
-  function (fuelbed reaction intensity, wind, slope, fuelbed bulk density, heat of preignition)

- Some basic “rules of thumb” to help in design

## Crown Fire

- Some basic “rules of thumb” to help in design

## Crown Fire

- Initiation
- Function (CBH, FMC)
- Crown fire spread
- Crown spread rate = function (FM 10 surface) fire rate w/ midflame windspeed @ 40% of 6.1 m (20 ft) wind speed
- Active crown fire  – function crown spread rate > (3.0/CBD)

- Some basic “rules of thumb” to help in design

## Crown Fire

## Spotting

## Spotting

- Can greatly increase rate of fire perimeter expansion (surface or crown)
- Function of:
- Stand height – higher lofting
- Tree species – embers production
- Species tolerance – more embers
- Species diameter – more embers & lofting

- Some basic “rules of thumb” to help in design

## M

- Canopy Base Height

- Canopy Bulk Density

- Fire Behavior Surface FM - Intensity

- Canopy Closure/FMC

**M**

**L**

- Moderate
- 1, 5, 6,
- 7, 9

- High
- 3, 4, 10,
- 11-13

- Low

- Moderate

- High

- Moderate

- Low

- Low

- Mod-High

**H**

- High

- Moderate

- 33

- 66

- 0

- 100

- Low
- 2, 8

- Fuels Fire Behavior Hazard - Example

- High Index = 70

## M

- Canopy Base Height

- Canopy Bulk Density

- Fire Behavior Surface FM - Intensity

- Canopy Closure/FMC

**M**

**L**

- Moderate
- 1, 5, 6,
- 7, 9

- High
- 3, 4, 10,
- 11-13

- Low

- Moderate

- High

- Moderate

- Low

- Low

- Mod-High

**H**

- High

- Moderate

- 33

- 66

- 0

- 100

- Low
- 2, 8

- Fuels Fire Behavior Hazard - Example

## Color Country “rules of thumb”

| Fuel Model | 1 | 2 | 5 | 6 | 8 | 9 | 10 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Type | Short to Mid Grass | Grass w/ Litter | Green Shrub | Flamable Shrubs | Compact Short Needle Litter | Longneedle
or Broadleaf Litter | Large to Small Down Woody w/ Litter |
| ROS | EH | VH | M | H | VL | H | M |
| FL | H | VH | M | M | VL | L | M |
| Heat per Unit Area | L | H | H | H | L | M | VH |
| Load | L | M | M | H | M | M | H |
| SA/V | H | H | M | M | L | H | M |
| Depth | L | L | M | M | VL | L | M |
| Mois.
Extinct | L | L | L | M | M | M | M |

## Wind Speed = 30 mph @ 20 ft flame height

**Wind Speed = 30 mph @ 20 ft flame height**

## NEXUS

## NEXUS

## NEXUS

## NEXUS

## Fuel Models

## Slide 36

## Slide 37

## Integrating Fuels With FRCC Inputs

- “rectification”

## Fire Regime Condition Class (FRCC)

There are obvious overlaps between FRCC, Fire Behavior/Effects input characteristics, and basic vegetation characteristics

Identify characteristics common to Fire Behavior/Effects model inputs, FRCC inputs, and basic vegetation characteristics

 Integrate treatment development and inputs to assure logical relationships

- There are obvious overlaps between FRCC, Fire Behavior/Effects input characteristics, and basic vegetation characteristics
- Identify characteristics common to Fire Behavior/Effects model inputs, FRCC inputs, and basic vegetation characteristics
-  Integrate treatment development and inputs to assure logical relationships

## Fire Regime Condition Class (FRCC)

-   BioPhysical Setting (BPS) – reference conditions
-   Succession Class (SC) – canopy cover, height, existing vegetation type, species composition
- Interrelationships
-    Logic relationships  between characteristics
-   illogical = treatment to create fuel model 2 & leave succession class as closed mid-seral

**Notes:**
Within fire regime condition class there are two inputs. 
Biophysical setting – this normally does not change since it is a land classification based on plant species or physical indicator attributes of site conditions.  In some cases major loss of soil, invasion of exotic species, or change from wildland to urban land use may change the biophysical setting.
Succession class – this is the existing vegetation composition and arrangement and thus changes with treatment; the input rules to succession class are described in the “Modeling Data Base.”  The inputs include existing vegetation type, cover, height, and information on species composition from the plot data base.  If succession class is changed then the existing vegetation themes may need to be changed, as well as associated fuel characteristic themes.
The important vegetation and fuel characteristics to cross-check are those that would produce maps with obvious illogical relationships or inputs that may produce illogical fire behavior, fire regime condition class, or habitat model outputs.

## Interrelationships

-   Fire Behavior Fuel model (FBFM)
-   Canopy cover (CC)
-   Canopy height (CH)
-   Canopy base height (CBH)
-   Canopy bulk density (CBD)
-   Existing vegetation type (EVT) - species
- Fire Regime Condition Class (FRCC)
-   BioPhysical Setting (BPS) – kind of site, native species
-   Succession Class (SC) – species, canopy cover, height, size
-   Existing vegetation type (EVT) – species

-    Relationships  between characteristics

## Interrelationships

| Characteristic | Cross-check |
| --- | --- |
| Canopy cover | Succession Class |
| Canopy height | Succession Class |
| Canopy base height | Succession Class |
| Canopy bulk density | Succession Class |
| Existing Vegetation Type | Succession Class |
| Existing Vegetation Type | Fuel Model |
| Fuel Model | Succession Class |
| Biophysical Setting | Existing Vegetation Type |
| Biophysical Setting | Fuel Model |

## Objectives

- Review of applications of surface & canopy fuel characteristics
- Relate fuel characteristics to fire behavior interpretations
- Understand and apply characteristics of surface, crown, and torching fire behavior
- Assess differences in fire behavior fuel model 13 system for treatment design
- Conduct logical checks on fire behavior and FRCC input data to assure consistency

## Fuels and Fire Behavior Modeling

**Fuels and Fire Behavior Modeling**

**Common Questions**

## Slide 45

## Problem Fire Characterization

- Threat to Urban Interface
- Large Fire Threat
- Fire Effects
- 	Uncharacteristic (FRCC)
- 	Soil, water
- 	Smoke
- 	........

## Problem Fire Characterization

- Calibrating FBAT (FlamMap)
- 	Fire Weather (primarily wind speed)
- 	Rate of Spread
- 	Flame Lengths
- 	Crown Fire Activity
- 	Fuel Characteristics

## Fire Family Plus

## 1 Hr Fuel Moisture

## Pocket Cards

## Fire Occurrence

- 1988

## Fire Occurrence

## Calibrating for FBAT/FlamMap

- Wildfire Potential Hazard Scenario
- Static upslope wind direction
- Static 98th percentile severe weather
- (1, 10, 100 hr, live herbaceous & woody)
- No change in weather
- Adjust wind to produce recorded fire behavior in these types of conditions

## Fire Behavior Assessment Tool – Absolute FB Class

## Slide 55

## Calibrating for FARSITE

- Wildfire Hazard Scenario
- Daily recorded weather of problem incident
- (dead and live fuel moisture)
- Or 98th percentile or other scenario
**Upslope winds**
- Variable daily temperature, humidity
- Adjust to produce recorded fire behavior in these types of conditions

## Slide 57

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## Slide 60

## Calibrating for FARSITE

- Wildfire Hazard Scenario
- Daily recorded weather of problem incident
- (dead and live fuel moisture)
- Or 98th percentile or other scenario
**Variable hourly wind direction & speed**
- Variable daily temperature, humidity
- Adjust to produce recorded fire behavior in these types of conditions

## Slide 62

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## “hours of boredom interspersed with seconds of pure panic”