1. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 7 Fire and the Forest

2. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter Highlights  Ways that fire is both beneficial and destructive  Three elements required for fire  Surface, ground, and crown fires and fuels  Major causes of destructive forest fires  Effects of wildfires

3. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter Highlights (Continued)  Use of prescribed burns  Methods of fire suppression  Government policy regarding forest fires

4. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fire as Friend and Foe  Benefits of fire  Cleans debris (plant material) from forest floor  Controls brush and thins stand  Destructive fires result from buildup of fuel on forest floor  May burn with such heat as to ignite foliage and cause trunks to explode  Second only to insects as cause of timber loss

5. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Three Elements Essential to Fire  Interaction of these elements controls the rate and intensity of a fire:  Availability and concentration of flammable fuels  Heat energy sufficient to raise fuel to combustion temperature  Adequate supply of oxygen  Change in any ingredient alters nature of fire

6. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Types of Fuel That Cause Fires  Surface fuels:  Undecayed dry plant materials and live plants on soil surface  Ground fuels:  Duff or litter composed of decaying plant material just below surface  Peat from bogs where decay is limited

7. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Types of Fuel That Cause Fires (Continued)  Aerial fuels:  More than 6 ft. above ground, upper foliage or canopy  This type of fire is called a crown fire

8. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fires Resulting from Different Fuels  Surface fire: moves quickly across surface, seldom intense  Reduces risk of more serious fires  Ground fire: can smolder for many weeks, limited by amount of oxygen available  Crown fire: ignited by intense surface fire

9. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Major Causes of Destructive Fires  Lightning: especially in drought conditions, aggravated by wind  Volcanic activity: rare in North America  Human activities: campfires, internal combustion engines, etc.  Loss of control of planned (prescribed) burns  Incendiaries: willfully set; more than one- fourth of all U.S. fires each year

10. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Wildfires on Forests  Massive damage due to size and unpredictability  Most serious in dry regions in periods of drought that follow periods of precipitation  Fire intense enough to reach crown kills trees  Some wildlife may benefit as forage plants fill in areas of former tree coverage  Endangered species at greater risk

11. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Wildfires on Forests (Continued)  Serious damage to soils as organic matter is destroyed, increasing possible erosion  Water quality damaged by resulting ash and silt

12. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Prescribed Burns Improve Forest Health  Best approach to dealing with wildfires is prevention  Goal of prescribed burns is to eliminate fire hazards  Reduces surface litter, which can fuel more destructive fires as it builds up

13. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Prescribed Burns Improve Forest Health (Continued)  Prescribed burns can be used to cleanse forest  Controls losses due to insects and disease  However, it may weaken trees and increase susceptibility to insects and disease

14. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Policy of Short-Duration Fire Cycle  Forest Service policy in recent years: broader scale use of prescribed burns  Will take many years to return entire forest to a short-duration cycle because of excessive fuel buildup on many forest floors  Safer to wait until after next harvest cycle before applying this practice

15. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fire Suppression Policy of U.S. Forest Service  Congress first funded fire control in 1911, 1924  1935: intense fire suppression policy  Impossible to implement for lack of equipment and personnel  Mid-1900s: fire priority approach  Suppression in high-value timber areas

16. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fire Suppression Policy of U.S. Forest Service (Continued)  Today: fire management  Surface fires allowed to burn if consistent with long-term objectives  Cost of suppressing fires versus cost of letting them burn

17. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Wind on Fire  Wind provides oxygen to fire  As wind direction changes, turbulence often evident  Can cause surface fire to become crown fire  Increased intensity can create strong winds  Fire creates its own draft (supply of fresh air)  Resulting firestorm may jump natural barriers and fire lines (known as spotting)

18. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Wind on Rate or Spread  Wind speed of 10 mph increases to 20 mph. How much does the increase in wind speed affect the rate at which the fire can be expected to spread?  Calculate R for a wind speed of 10 mph: 1.R = 102 2.R = 100

19. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Wind on Rate or Spread (Continued)  The rate of spread at 10 mph has an index of 100  Calculate R for a wind speed of 20 mph: 1.R = 202 2.R = 400  The rate of spread at 20 mph has an index of 400 or four times the rate of spread when compared to a wind speed of 10 mph. The rate of spread quadrupled when the wind speed doubled

20. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Indirect Attack Method of Fire Suppression  Indirect attack: isolates fire from fuel supply  Create firebreak or fire line in pathway of fire  Removal of fuel from a strip of terrain  Set backfire to gain control of crown fire  A fire set along inside edge of firebreak to burn fuel back toward fire  Establishes a wide barrier  May force fire to change direction

21. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Indirect Attack Method of Fire Suppression (Continued)  Backfires remove fire fuel from an area, so when an advancing fire meets the burned out area, it will have nothing to feed on

22. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Direct Fire Attack  Water and fire retardant chemicals are applied to fires from aircraft, trucks, and backpacks. It is a common practice to make airdrops of fire retardant chemicals

23. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Direct Attack Method of Fire Suppression  Direct attack: employs water or fire retardant chemicals to suppress fire  Lowers temperature of fire below kindling point  Interrupts oxygen supply to fire  Applied from aircraft, trucks, backpacks

24. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Direct Attack

25. ©2013 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Government and Industry Efforts to Prevent Forest Fires  Educating public about forest fire prevention with a themed campaign  Keep America Green  Smokey Bear  Providing educational materials to schools  Signs, brochures, other media promotions  Elimination of fire hazards in forests