1. Fire Behavior and Prescribed Fire

2. Heat Fuel Oxygen Fire Triangle

3. Three Principal Environmental Elements Affecting Wildland Fire Behavior

4. Fuels Fuel Type Fuel Moisture Size and Shape Fuel Loading Horizontal Continuity Vertical Arrangement

5. Fuel Moisture The amount of water in a fuel expressed as a percentage of the oven-dry weight of that fuel

6. Fuel Types Nonburnable Fuel Type Models (NB) Grass Fuel Type Models (GR) Grass-Shrub Fuel Type Models (GS) Shrub Fuel Type Models (SH) Timber-Understory Fuel Type Models (TU) Timber Litter Fuel Type Models (TL) Slash-Blowdown Fuel Type Models (SB)

7. Fuel moisture time lags: (Time it takes for a fuel to lose 63% of its moisture) Time lagFuel diameter 1-hour (fine fuels) <¼ inch (twigs, dead grass, leaves, needles) 10-hour ¼-1 inch (twigs, small branches, cones) 100-hour 1-3 inch (branches, tops) 1000-hour >3 inch (large branches, tops, logs) Fuel Size

8. Fuel Loading The quantity of fuels in an area Generally expressed in tons per acre

10. Horizontal Continuity: Uniform vs Patchy Vertical Arrangement Ground Surface Aerial

11. All combustible materials lying beneath the surface including deep duff, roots, rotten buried logs, and other organic material Usually called a “PEAT FIRE” Ground Fuels

12. All materials lying on or immediately above the ground including needles or leaves, grass, downed logs, stumps, large limbs and low shrubs. Surface Fuels

13. All green and dead materials located in the upper forest canopy including tree branches and crowns, snags, moss, and high shrubs. Aerial Fuels

14. Weather Temperature Wind Speed and Direction – Increases supply of oxygen – Drives convective heat into adjacent fuels – Influences spread direction and spotting – Carries moist air away replacing it with drier air – Dries fuels – Raises fuel moisture if the air contains moisture

15. Weather Relative Humidity (RH) – As RH increases, fuel moisture increases Precipitation – Increase fuel moisture

16. Topography Aspect Slope Position of Fire Shape of Country Elevation – Relates to curing of fuels, precipitation, length of fire season, etc. Aspect Slope Position of Fire Shape of Country Elevation – Relates to curing of fuels, precipitation, length of fire season, etc.

17. Aspect

18. Steep Slopes Cause Rapid Fire Spread

19. Slope Affects Fire Behavior Preheating Draft Faster Ignition and Spread Burning Material Rolling Downslope

20. Position of Fire on Slope

21. Box Canyon & Chimney Effect

22. Radiant Heat Across Narrow Canyon

23. Spotting Across Narrow Canyon

24. Mountains Cause Channeling of Wind

25. Elevation

26. Characteristics of Fire Behavior Fire Intensity: Heat release per unit time (BTUs) Fire intensity affected by – Fuel loading – Fuel moisture content – Compactness or arrangement of fuels

27. Flame Length: The distance measured from the average flame tip to the middle of the flaming zone at the base of the flame

28. Rate of Spread (ROS): The distance a fire travels during a given period of time

29. Rate of spread = distance/time Burned Area Increased fire intensity Windspeed Steepness of slope Primary factors affecting rate of spread?

30. Slope Reversal

31. Running Types of Fire Behavior – spreading quickly Creeping – spreading slowly with low flames Smoldering– burns without flames; barely spreading Spotting– sparks/embers carried by wind or combustion column or moved by gravity Spot fires– new ignition points Fire brand– a piece of burning material

32. Torching Types of Extreme Fire Behavior – surface fire moves into crowns of individual trees Crowning – spreads from tree crown to tree crown (dependent, active, or independent) Flareup – sudden acceleration of fire spread or intensity (short duration, for portion of fire) Blowup– dramatic change in the behavior of the whole fire (rapid transition to a severe fire) Fire Whirls– vortex (gas mass with rotational motion)

33. Fire Effects

45. Prescribed Fire

46. Prescribe Fire Plan Burn prescription written Pre-burn site treatments completed Equipment designated & ready Personnel identified & trained Approvals & permits in hand Authorities & interested parties identified & notified* Latest forecasts checked* * Day before & day of burn

47. Ignition Devices Hand-held/ground-based – Drip torch – Propane torch – Fire fuse (flare) – Flame thrower

48. Drip torch fuel: 3:1 or 3:2 Diesel/gasoline

52. Ignition Devices Aerial – Helitorch – Delayed aerial ignition device (“ping-pong balls”)

53. Helitorch

54. Delayed aerial ignition device

55. Ignition Devices Lightning

56. Ignition Techniques Backfire (backing fire) – Least intense & most predictable – Short flame lengths – Narrow burning zone – Slow rate of spread – Low smoke output

57. Backing Fire

58. Headfire (heading fire) – Most intense and unpredictable – Long flame lengths – Wide burning zone – Fast rate of spread – High smoke output

59. Strip-heading Fire Distance between strips controls intensity

60. Spotfire – Intensity intermediate between back & head fires – Useful in shifting winds – Spots merge to form a strip head fire – What you get using a DAID

61. Spotfire Distance between spots controls intensity

62. Flankfire (flanking fire) – Intensity intermediate between back & head fires – Fire spreads at right angle to wind – Limited to steady wind conditions – Requires careful crew coordination – Used primarily for securing flanks of back or head fires

63. Flanking Fire

64. Headfire Flankfire Backfire Wind

65. Smoke Management

66. Principles of smoke management Have clear, defensible objectives Comply with local pollution regulations Notify local fire & law enforcement officials, nearby residents, & adjacent landowners Obtain the best available weather forecasts Don’t burn under highly stable conditions Burn during midday; avoid night burns Use caution near, upwind, or up-drainage of smoke sensitive areas

67. Principles of smoke management (continued) Use test fire to estimate smoke output & behavior Use backing fires if feasible Burn in small blocks if dispersion marginal Do not burn when fuel moisture high Don’t burn organic soils Mop-up along roads first Have an emergency plan!