Chapter IX: Interagency Prescribed Fire Training
Leda N. Kobziar
School of Forest Resources and Conservation
University of Florida

 Objective: Understand the what and how of fire’s role in Florida’s ecosystems
 Fire dependent ecosystems of
Florida, their fire regimes
 Fire’s effects on ecosystem components e.g. water, soil, vegetation, fauna
 Relationship between timing/season of fire and ecosystem effects
 How to manipulate fire regime attributes to encourage specific ecological responses

Objectives
1) Identify fire’s primary effects on the basic physical ecosystem components of water and soils.
2) Identify fire’s primary effects on floral (plants) and faunal
(animal) components of ecosystems.
3) Identify common Florida fire-dependent ecosystems and frequency of fire return intervals that sustain them (IN YOUR
BOOK)
4) Understand the relationship between season or timing of fire applications and certain ecosystem responses.
5) Understand the connection between burn prescription parameters and ecological effects.

• Fire history (pyrodendrochronology, reconstructions, sediment and pollen charcoal analyses)
• Fire regimes
• Fire dependence or adaptations of plants and animals- AUTECOLOGY
• Fire effects on water, plants, animals, from individuals to populations, communities, ecosystems, landscapes.
• Fire effects on nutrient, energy, and carbon cycling

1986-1997
300
# of Acres (x 1000)
300
250
200
150
250
200
150
100
50
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
# Acres
0
100
50
Florida’s Historical Fire Regime: May-June

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Native Americans burned to stimulate grasses and forage, acorn production, reduce fuels and pests, clear land for agroforestry, increase access, herd game, etc.
Practices adopted by European Settlers (c. 1700s to mid 1900s)

 Thousands of yrs of repeated burning  ecosystem structure & composition
 Selected for fire-resistant or fire-
 dependent species (e.g. longleaf pine, red cockaded woodpecker) and communities
Resulted in 26 fire dependent and/or influenced communities in Florida alone (1/3 rd of 81 total).
Chris Evans

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The Florida Natural Areas Inventory lists 81 communities in Florida:
18 of these are considered FIRE DEPENDENT– will change significantly if any aspect of the fire regime is changed for a given length of time.
These ecosystems cover the majority of non-developed land area in Florida. Examples:
 Sandhill, Upland Pine Frequent, 1-3 yrs
 Scrub Variable, 5-30 yrs
 Dry Prairie Frequent, 1-2 yrs
 Mesic Flatwoods Frequent, 1-4 yrs
 Scrubby Flatwoods Variable, 5-15 yrs
 Wet Flatwoods Frequent, 3-10 yrs
 Glades Marsh approx. 2-5 yrs
 Marl Prairie Frequent, 1-6 yrs

UNSUSTAINABLE HARVESTING & FIRE
SUPPRESSION  FOREST DEGRADATION: ~3%
ORIGINAL FOREST REMAINING
1) Lack of seed sources, regeneration of fire adapted species
2) Altered soil fertility, pH, texture, mycorrhizae…
3) Loss of fire-structure dependent wildlife spp.
4) Closed communities with limited early successional species recruitment
5) Changes in flammability and fuels structure
6) Fuel load build-up  larger, less predicable, higher severity, more costly wildfires

IN THE SOUTH, REVERSING THE LEGACY OF SUPPRESSION
AND DEGRADATION MEANS USING PRESCRIBED FIRE TO
RESTORE AND MAINTAIN NATIVE ECOSYSTEMS

FIRE REGIME ATTRIBUTES
• Fire frequency
• Seasonality
• Extent of area burned/ landscape heterogeneity
• Type (crown, ground, surface)
• Intensity
• Severity
• Synergy, interaction with other disturbances
• Includes using fire with mechanical treatments, silviculture, CLIMATE

Frequent fire
Infrequent fire
Longleaf pine
Southeastern US
Fire 1-4 years
Low intensity, understory,
Spring/ summer
Florida Big Scrub (sand pine) Fire 30+ years, high intensity, crown, spring or summer, large areas
Randy Cyr
Basin swamp
Fire > 5-150 years, small area, mixed severity, only burns during drought (peaty soils)

The South burns more than any other region of similar size in the world…but still doesn’t meet fire rotation goals

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Southern Region:
354 M acres forest pre-settlement
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 How many acres would have burned historically to maintain a 10-yr average FRI across the forests?
200 M acres forest today
8 M burned…how much more should be burned?
Caveat: “forest” includes plantations, which are not subject to the historical FRI…but you get the picture!

F I R E R E G I M E S C O R R E S P O N D T O T H E D I S T R I B U T I O N O F F L N AT I V E E C O S Y S T E M S
Shrub Wetland Bay head
Hydric
Hammock
Low scrub
Pine
Flatwoods
Slash pine scrub
Mesic
Hammock
Sand Pine
Scrub
High
Pine
Oak scrub
Rosemary
Bald
Xeric
Hammock
Fire Interval

Without fire sand pine scrub will likely succeed to xeric oak/hickory scrub.
Fire Regime
• 30+ year fire return interval
• Late spring / early summer fires associated w/ drought, high winds, low RH and high temperature
• High-intensity, larges scale, standreplacing crown fires
• Auto-successional (fire climax) ecosystem
• Pinus clausa (sand pine) is serotinous

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Given this knowledge of fire ecology:
Sand pine doesn’t burn well unless it’s a drought, or around
March-May when resin content is highest and MC is lowest
The cones require high heat; the crowns of the trees must be burned
The seeds require bare mineral soil
Younger trees don’t produce enough viable seeds to regenerate a stand, are killed by fire

Senescent
Mature b b b b a a a a adequate for overstory restocking

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Directly
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Fire Frequency
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Fire Season
 Area Burned
Indirectly
Fire Type
Fire Intensity
 Fire Severity
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Low density, mature overstory
(BA < 15 m 2 /ha)
Small regeneration gaps
Grassy understory, diverse herbaceous component
High C sequestration
Low hardwood occupancy
Wildlife habitat function
(imperiled species: red cockaded woodpecker, gopher tortoise, skink, etc.)
Wildfire mitigation function: reduce severity by reducing fuel loads

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Southern Fire Exchange: hub for resources http://southernfireexchange.org/index.html

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Competition for moisture, nutrients & light are temporarily reduced
Species composition and successional stages are altered
 Earlier seral stage, but not always
Structure of community may change
 e.g. susceptibility to blowdown
 Fuel profiles may change fire effects
Certain species may be selectively eliminated or selected for based on their degree of fire adaptation
 This changes over the life cycle of a plant/ phenology

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Flower & seed production stimulated (e.g. wiregrass)
Seed germination stimulated
(seed or soil conditions)
Rapid growth & development (e.g.
longleaf pine)
Fire-resistant bark, self pruning of ladder fuels (most pines, mature
hardwoods)
Adventitious buds (gallberry, pond
pine)
Root/ tuber/ rhizome sprouting, and storing carbohydrates (oaks, saw palmetto, perennial grasses)
Serotinous cones (sand pine)
Flammability (?)

12
10
8
6
4
2
0
Foliage mortality
126 134 142
Temperature F
150
Hiers et al. Final Report: JFSP 01-1-3-11

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Crown scorch (dead foliage)
 increases as air temperature increases
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 may not kill crowns of longleaf and slash pines
Crown mortality affected by: stand & shrub density fuel concentrations at the base of trees bud dormancy & heat resistance foliar moisture content
 presence of flammable compounds
 Season!!! Resistance high when dormant, lower in late summer

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Stem & cambium mortality affected by:
 bark thickness & heat resistance
 stem diameter & degree of heat girdling
 heat received during all stages of combustion
Damage to tree stems managed by:
 controlling fire intensity, flame length, and residence time
 reducing duff & litter consumption where long unburned

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Root mortality affected by:
 depth of lateral and feeding roots
 moisture content of duff/litter and surface soils
 duration of fire heating
Damage to roots managed by:
 knowing where roots are located
 regulating duff & litter consumption by burning at specified moisture contents
 Drought indices are important to consider
 Influence duff consumption
Hiers et al. Final Report: JFSP 01-1-3-11

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Fuel & stand characteristics affect lethal heating
 Heat disperses in open stands
 High fuel loads increase heat release
 High fuel moisture content decreases heat
 Litter and duff accumulations increase heating at base of stem
Therefore, burn prescriptions also affect mortality: fire regime attributes:
 Frequency: Frequent fires reduce fuel loads
 Intensity: Ignition pattern (how so?)
 Season of burn

 Mortality may develop slowly (even over a period of several years)
 Damage in one part of plant stresses other parts
 Secondary infection by insects or fungi
 Post burn environment matters (drought/rain)
Bark beetle pitch tubes

 Sprouting is the recovery mechanism in most hardwoods and shrubs:
 Roots, root crowns, dormant stem buds, rhizomes
 Survival related to depth, location
 dependent on season and fire severity
 most sprouting : low intensity, dormant season burns
 least sprouting :
▪ high intensity, growing season fires
▪ low soil moisture
▪ High organic matter consumption
 exceptions when reproductive parts deep in soil

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Reproduction by seed after a prescribed fire can be managed by:
 knowing the seed ecology of a species
 Burn prescription
 size and/or intensity of burn- seeding species often require bare mineral soil. What does this suggest about desire litter/duff consumption/ severity?
 season/timing of burn- post burn precipitation is important!
Schedule burns to take advantage of seasonal responses

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Plants vary in adaptations to fire
Fire effect is created by interaction of weather, fuel conditions, fire behavior, & site moisture
Post-fire conditions significantly affect recovery & productivity
Plant community responses are predictable, if you learn about plant ecology
Landowner should monitor burning conditions and post-fire responses and make changes to subsequent prescriptions as necessary

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Many Florida species have evolved in a fire environment
Mortality levels are generally low
(direct effects)
Indirect effects on cover and food sources can be substantial but vary across the landscape and diminish with time

Smokey’s great grandson?
• Animals with limited mobility
(young, old, small animals) are more vulnerable to injury and mortality than animals with high mobility (mature or larger animals, flying species).

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Cover is temporarily decreased
Microclimate is modified
Food sources & nutritional quality increase
 plant species diversity increases
 foliage of new herbaceous plants and shrub sprouts is more palatable and higher in nutrients
(N,P) and crude protein
 seed production of many species increases
 abundance and diversity of insects may increase
 prey are more visible for predators

Grant Steelman

Example: WILD TURKEY ROTATION PATTERN
Mixed burn rotations such as the one above with a three year rotation provide adequate nesting and escape habitat when the adjacent unit has been burned. Mix dormant/growing season burns (Grant
Slide: Grant Steelman

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Increase number of stems of many hardwoods and shrubs ***
Generally doesn’t kill larger diameter hardwoods (e.g. oaks)
Favors bird species that prefer shrubby hardwood habitats

FIRE SEASON: EFFECTS ON UNDERSTORY, FIRE
BEHAVIOR, SUMMER VS. WINTER
Saw palmetto: 80% annual growth in summer

10 mo. post burn

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Deciduous hardwoods most susceptible to damage
 Can be top killed after leafing out, don’t have carbo.
Reserves to respond
 Positive for hardwood control
 May be a negative for mast production for wildlife
May damage gamebird nests and brood, but food supplies probably not a problem, especially with patchy fires

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Stimulate flowering/seed production of many grasses and forbs increase number of original plants that flower
 increase number of flowering stems per original plant
Higher damage to shrubs and hardwoods
 Top-kills larger, more stems than dormant season burn
 reduces amount of resprouting
 increases percentage of individuals completely killed

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If fire conducted during rainy, humid weather, results may be more patchy than in dry weather
 a positive for wildlife habitat
 a negative for some other objectives
Small pines may be damaged by intense fire if ambient temperatures are high
Favor birds that prefer open woodlands & grasslands

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Evergreen trees (pines) & shrubs (including palmetto & gallberry) most susceptible to damage!!!!
Most hardwoods will not be affected

How do we manipulate fire to achieve desired ecological effects? Burn Prescription
Parameters.
What will influence fire’s behavior that will result in
1) Weather parameters before, during, and after the burn (Air temp., RH, precipitation, wind)
2) Timing of the burn
3) Ignition patterns

Firing Plans/Ignition Patterns
1) Slow moving fires of all types are hotter at the soil surface, and have more potential to heat and ignite ground
2) To minimize the degree of fire severity, limit the fire residence time
3) The pattern of ignition (how the fire is applied, could be solid line, point source or a combination) will alter the intensity of the resultant fire
 ecological effects

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Major factors that influence ecosystems:
 Depth to water table
 Fire frequency , fire regimes
Effects on animals include:
 Direct Mortality - MINOR
 Habitat changes – can be MAJOR ( + )
Wildlife, plant diversity and numbers increase with a mosaic of successional stages created by a variety of fire prescriptions over time
 Pyrodiversity promotes habitat diversity promotes species diversity