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