Prescribed Burning What is prescribed burning? Why do we used prescribed burning? What are the...
-
Upload
branden-johns -
Category
Documents
-
view
228 -
download
0
Transcript of Prescribed Burning What is prescribed burning? Why do we used prescribed burning? What are the...
Prescribed Burning
• What is prescribed burning?
• Why do we used prescribed burning?
• What are the effects of prescribed burning?
• What influences fire behavior?
• What are the different firing techniques?
• How do we contain a prescribed burn?
• What is a burn plan?
• How is a burn permit obtained?
Prescribed Burning
• What is Prescribed (Controlled) Burning?– Controlled application of fire
• Vegetative fuels• Specified environmental conditions• Following precautionary measures• Appropriate intensity & rate of spread• Meet habitat management objectives
Credit: forestryimages.org
Prescribed Burning
• History of Prescribed Burning– Wildfires
• High lightning– Southeast: natural peak in June-July
• Large areas
– Used by Native Americans & Early settlers• Mimic natural fires & manage land• A custom is established
Prescribed Burning
• History of Prescribed Burning– Fire suppression movement began in the late 1890s
• Fire destroys!• Gifford Pinchot - USFS
– Industrial logging & fires– Fire control the principal duty of US Forest Service
– USFS experiments with light burning in 1910• It was destructive
– Smokey the Bear introduced mid-1940s• Fires are bad
Credit: Flickr.com
Prescribed Burning• History of Prescribed Burning
– Prescribed burning banned for 50 years
– Changes in forest structure & composition• Longleaf ecosystems of the SE
– Prescribed burning reintroduced in the 1970s
Credit: prairiefriends.org
Prescribed Burning• History of Prescribed Burning
– Most state & federal agencies & private
– 3.2 million ha (8 million ac) of land burned annually in the South
• Fuel reduction• Wildlife & range management• Ecosystem restoration
– Challenges
Prescribed Burning• Why Use Prescribed Burning?
– Wildlife managers• Set back succession – mimic natural processes
– Favor understory & ground cover– Early successional species– Mast & herbage production– SE: many game and T&E wildlife species
(Encyclopedia Britannica 2008)
Prescribed Burning
• Why Use Prescribed Burning?– Reduce hazardous fuels
• Reduce heavy roughs (>5-6 yrs fire suppression)
– Prepare site for seeding & planting– Manage competing vegetation
• Hardwood (e.g., oaks) & shrub (e.g., saw palmetto) control
• Exotics
Credit: forestryimages.org Credit: forestryimages.org Credit: forestryimages.org
Prescribed Burning
• Why Use Prescribed Burning?– Control insects & disease
• White pine cone beetle (burn cones on ground)
– Improve forage quality & quantity• Calcium, phosphorous, & protein
– Wiregrass
– Enhance appearance & improve access– Perpetuate fire-dependent species (e.g., orchids)
Credit: landscapeonline.com Credit: dnr.state.oh.us
Prescribed Burning
• Effects of Prescribed Burning– Vegetation
• Dependent on– Plant physiology– Fire intensity– Topography– Season of burning– Frequency of burning
Prescribed Burning
• Effects of Prescribed Burning– Vegetation
• High temperatures– Directly damage via combustion– Indirectly disrupt physiological processes via radiant heating
– Mortality dependent on exposure to lethal temps» Short exposure to high temps» Long exposure to lower temps
Prescribed Burning
• Effects of Prescribed Burning– Vegetation
• Mortality influenced by – Growth stage- meristem tissue & cambium killed– Pre-fire conditions/stressors- drought, flood – Post-fire stressors- herbivores, pests, & disease
Credit: about.com
Prescribed Burning
• Effects of Prescribed Burning– Vegetation
• Fire-adapted traits– Growing points, cambium, & propagules protected or
removed from exposure» Ponderosa & longleaf pines (thick bark/protection)
– Death but fire activated seed banks
Credit: cdu.edu.au
Prescribed Burning
(FWS 2008)
Prescribed Burning
• Effects of Prescribed Burning– Vegetation
• After fire plant community includes– Plants that survived fire intact– Sprouts or suckers from top-killed plants– Plants that established from seed
Credit: inhs.uiuc.edu
Prescribed Burning
• Effects of Prescribed Burning– Vegetation – sometimes difficult to predict
• Change plant community composition– Set back succession
• Alter plant community structure– Consuming dead & living plants, litter, CWD, etc.– Openings & bare ground
• Change vegetation patterns– Often more diverse
Prescribed Burning
• Effects of Prescribed Burning– Wildlife
• Direct mortality – typically little– Limited mobility
» Nests, nestlings, & juveniles
– Flee– Seek refuge
Credit: arkive.org
Prescribed Burning
• Effects of Prescribed Burning– Wildlife
• Immediate response determined by– Season– Intensity– Rate of spread – Uniformity– Size
Prescribed Burning
• Effects of Prescribed Burning– Wildlife
• Long-term effects on habitat > than on animals– Food & cover– Survival & reproduction– Movements
» Temporary» Attraction to burns
Prescribed Burning
• Effects of Prescribed Burning– Water
• Potential for increased runoff & erosion– Soil particles– Nutrients
Prescribed Burning
• Effects of Prescribed Burning– Air
• Smoke (depends on type of fire & atmospheric conditions)– Particulates (ash particles, partly consumed fuel, liquid droplets)
» Visibility issues– Effects on human health & welfare
Credit: forestryimages.orgCredit: forestryimages.org
Prescribed Burning
• Fire (Combustion) Triangle– How we burn: requirements for fire
Prescribed Burning
• We need to understand: Fire Behavior – How hot– How fast (residence time)– How continuous or patchy– How high (scorch height)– Completeness of combustion – Other characteristics
Affects habitat & wildlife
Credit: fws.gov
Prescribed Burning
• Fire Behavior affected by– Fuel load– Weather
- Temperature - Relative Humidity
- Precipitation - Wind
- Atmospheric dispersion
– Chemical factors– Topography
Prescribed Burning
• Fire Behavior– Fuel load
Total dry weight of fuel/unit of surface area• Potential (total) v. Available (actually consumed)
– Out of reach, high moisture content, etc.– Difficult to separate
Credit: pwrc.usgs.gov
Prescribed Burning
• Fire Behavior– Fuel load affects
• Fire spread & intensity influenced by – Species of fuel– Size– Arrangement– Moisture content
Prescribed Burning
• Fire Behavior– Fuel load
• Determines– Likelihood of ignition – is there enough fuel– Maximum energy available to fire (intensity)– Fire continuity (spread)
– Low fuel load needs» Higher temp and wind» Lower humidity
• How long since last fire• Productivity of site
(Whelan 1995)
Prescribed Burning
• Fire Behavior– Weather – we need to know
• Key to successful burning– Control– Smoke management
• Forecast for day of burn & following night• Sources of weather information
– National Weather Service– State Forestry Agencies– Local Observations– Private Weather Forecasting Services
Prescribed Burning
• Fire Behavior– Weather- temperature
• >20 C (>68 F)– Higher temps- generally drier fuel = greater intensity
» Higher/total fuel consumption» Need greater control
• <30-32 C (<85-90 F)
Prescribed Burning
• Fire Behavior– Weather- relative humidity
• Moisture & temperature effects– 20 F increase = ½ reduction in rel. humidity (and other way)
» Often in morning (and afternoon)» After cold front its cooler & drier (optimum burning)
• Preferably 30-55%– <30%
» Very high intensity» Increased risk of spotting
– >55%» Patchy burn
Prescribed Burning
• Fire Behavior– Weather- precipitation
• Soil Moisture*– Damp soils protect roots & microorganisms– Retain some organic material– Cease burning during drought– Several days of good burning
» 0.6-1.3 cm (¼-½ in) rain» Brisk wind» Sunny skies» Low humidity
Prescribed Burning
• Fire Behavior– Weather- precipitation
• Fine fuel moisture- upper litter– 10-20% ideal– <6-7% damage– >30% poor burn
– 20-25% with heavy fuel build up
Rough estimate with needle bending
Prescribed Burning
• Fire Behavior– Weather- precipitation
• Fine fuel moisture- lower litter– Must be damp – typically greater than upper layer
» Dew & light precipitation problems
– Ignition of organic soil
More smoke with moist fuels
Credit: blogspot.com
Prescribed Burning• Fire Behavior
– Weather- wind• Generally increases through early afternoon
• Fire-weather forecasts are max. not mean
• Eye-level: 1.6-6.4 kph (1-4 mph)
• 6.1 m (20 ft): 9.7-32.2 kph (6-20 mph)
• Higher wind speeds steadier in direction
• Potentially risky to burn on calm days
Fires more predictable with steady wind speed & direction
(Often in winter; following for a few days after cold front; then winds often turn easterly which is undesirable)
Prescribed Burning
• Fire Behavior– Weather- wind
• High winds dissipate heat of backing fires– Less crown scorch
• Heading fires need low-medium winds– Preheating
– Eye level: 1.6-3.2 kph (1-2 mph)– 6.1 m (20 ft): 9.7-22.5 kph (6-14 mph)
Prescribed Burning
• Fire Behavior– Weather- atmospheric dispersion
• Determined by height of mixing layer
• Stability- slightly unstable or neutral– Greater instability lowers mixing height
• Mixing height- >518 m (>1700 ft)• Transport wind speed- 14.5-32.2 kph (9-20 mph)
Credit: forestry images.orgCredit: forestry images.org
Prescribed Burning
• Fire Behavior– Chemical factors
• Oils & resins– Increase burn intensity
• Mineral elements (e.g., P, S)– Decrease burn intensity
Prescribed Burning
• Fire Behavior– Topography- slope
• Downhill- slow• Uphill- fast
(Whelan 1995)
Prescribed Burning
• Firing Techniques– Ignition & movement (not method of ignition)
– Technique chosen appropriate• Burning objectives• Fuels• Topography• Weather conditions
Credit: firecenter.umt.edu
Prescribed Burning
• Firing Techniques– Backing fire– Heading fire– Flanking fire (right angles)– Spot fire
Credit: fl-dof.com
Prescribed Burning
• Firing Techniques– Backing fire
• Against the wind• Baseline/anchor point
• Often safest– Beginners– Fire hazards
Prescribed Burning
• Firing Techniques– Backing fire
• Produces minimal crown scorch• Used in heavy fuels & young stands• Wind speed little effect on rate of spread• Moves at 20-60 m/hr; used on smaller areas• Often used to establish base control line
Credit: fs.fed.us
Prescribed Burning
• Firing Techniques– Heading fire
• With the wind
(Whelan 1995)
Prescribed Burning
• Firing Techniques– Heading fire
• Used in most fuel types (not heavy)– Light & discontinuous
• Low wind speed required (Eye-level: 1-2 mph)• Burns with high humidity & fuel moisture
• Care needed– Quick spread– Taller flame/scorch– Pre-heating
Prescribed Burning
• Firing Techniques– Flanking fire
• Line of fire set into the wind
Prescribed Burning
• Firing Techniques– Flanking fire
• Used to burn small areas• Alternative to head fire• Light to medium fuels needed• Requires constant wind direction
• Intermediate to back & head fires
Prescribed Burning
• Firing Techniques– Spot fire
• Series of fires set at predetermined spacing– Optimal spacing
Prescribed Burning
• Firing Techniques– Spot fire
• Used with uniform light to medium fuels• Variable winds acceptable• Burns with low temp & high fuel moisture
Prescribed Burning
• Firing Techniques– Perimeter fire
• Care needed: intense fires & spotting
– Chevron fire• In hilly areas; lines along ridges
(Payne 1992)
Prescribed Burning
• Fire Containment– Firebreaks
• Fire roads, fire lines, fuel breaks
• Keep fire contained to designated area– Gap in Vegetation– Barrier to progress of fire
Prescribed Burning
• Fire Containment– Types of firebreak
• Natural*– River– Lake– Canyon– Nonflammable vegetation (e.g., oak hammock)
• Man-made– Roads– Trails– Cultivated soils– Soil strips
Credit: about.com
Prescribed Burning
• Fire Containment – Width of firebreaks
• Fuel dependent– Two parallel strips 30-90 m apart– Low fuel load: 2-3 m wide strips– High fuel load: >5 m wide strips
» >1 month before fire
– Florida: single strip 2-5 m wide
Credit: totalearthworks.co.au
Prescribed Burning
• Personnel & Equipment– Number of people required
• Size of area to be burned• Fuel, weather, & topography • Experience level of burn crew• Usually 6-12 people
Credit: audubon.org
Prescribed Burning
• Personnel & Equipment– Two-way radios– Ignition devices & fuel– Fire suppression equipment– Weather kit– Fence cutters
Credit: daylife.com
Prescribed Burning
• Ignition Devices– Drip torch– Flame thrower (terra torch)– Helitorch– Flare pistols– Pyroshot Hand Launcher– Electrical ignition (e.g., primacord)– Fuses– Delayed Aerial Ignition Devices
• Balls of potassium permanganate & ethylene glycol
Credit: pc.gc.ca
Credit: mdconsult.com
Prescribed Burning
• Ignition Devices– Fuel mixture (e.g., drip torch)
• 3 to 1 - diesel to gas– More gas to increase volatility– More diesel to increase adhesion, burn time, & heat
» FWC: 2:1
Credit: pc.gc.ca
Prescribed Burning
• Burn Plan– Geographic location – Sources of emergency assistance – Description of the prescribed burn unit area
• Vegetation, fuel, etc.
– Goals & objectives – Fuel & weather prescription – Desired fire behavior to meet objectives
Prescribed Burning
• Burn Plan– Smoke management – Crew– Equipment – Day of burn operations– Contingency plan– Safety & medical information – Post-burn activities
Credit: daylife.com
Prescribed Burning
• Burn Permit– In FL must be obtained before burning
• FL Forest Service (Division of Forestry)
– For uncertified & certified burns• Adequate firebreaks around burn area• Sufficient staff & firefighting equipment• Burn remains within authorized area• Have someone present until fire extinguished
– No spreading flame
Prescribed Burning
• Burn Permit– For certified burn
• A written burn plan to FLFS• Certified burner on site with plan
• Liability
Prescribed Burning
• Prescribed Burning– Effects– Influences on fire behavior– Firing techniques– Fire containment– Burn plans– Burn permits