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Ecological Effects- short version Chapter IX: Interagency Prescribed Fire Training. Leda N. Kobziar School of Forest Resources and Conservation University of Florida. Ecological Effects - Outline. Objective: Understand the what and how of fire’s role in Florida’s ecosystems - PowerPoint PPT Presentation
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Leda N. Kobziar School of Forest Resources and Conservation
University of Florida
Ecological Effects- short version
Chapter IX: Interagency Prescribed Fire Training
Ecological Effects - Outline
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
Fire in Florida
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.
What does fire ecology entail?
• 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
Why is fire ecology important in the south?
US Wildfires by Region: 2000-2010
Fire in Florida
# of Lightning Fires in Florida1986-1997
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonth
0
500
1000
1500
2000
2500
3000# of Fires
0
500
1000
1500
2000
2500
3000
# Fires
Fire in Florida
# of Lightning Fire Acres1986-1997
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonth
0
50
100
150
200
250
300# of Acres (x 1000)
0
50
100
150
200
250
300
# Acres
Florida’s Historical Fire Regime: May-June
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)
12,000+ yrs of Lightning + Anthropogenic Fire Use
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 (1/3rd of 81 total).
Legacy of anthropogenic and lightning fires
Chris Evans
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 ScrubVariable, 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
Repercussions of long-term burning FL Fire Ecosystems
UNSUSTAINABLE HARVESTING & FIRE SUPPRESSION FOREST DEGRADATION:
~3% ORIGINAL FOREST REMAINING1) 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
What’s in the prescribed burner’s “restoration toolbox”? 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
Longleaf pine Southeastern USFire 1-4 yearsLow intensity, understory, Spring/ summer
Florida Big Scrub (sand pine) Fire 30+ years,high intensity, crown, spring or summer, large areas
Basin swampFire > 5-150 years, small area, mixed severity, only burns during drought (peaty soils)
Randy Cyr
Frequent fire
Infrequent fire
Examples of Historical FL Fire Regimes
The South burns more than any other region of similar size in the world…but still doesn’t meet
fire rotation goals
Quiz
Southern Region: 354 M acres forest pre-settlement
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!
Dept
h to
Wat
er Ta
ble
(m)
Fire Interval
Pine Flatwoods
High Pine
Sand Pine
Scrub
Shrub Wetland
Sava
nna
Mar
sh Bay head Hydric Hammoc
k
Mesic Hammoc
k
Xeric Hammoc
k
Slash
pine scru
b Rosemary scrub
Low scrub
Oak scru
b
Rosemary scrub
Rosemary Bald
FIRE REGIMES CORRESPOND TO THE DISTRIBUTION OF FL NATIVE ECOSYSTEMS
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, stand-replacing crown fires
• Auto-successional (fire climax) ecosystem• Pinus clausa (sand pine) is serotinous
Without fire sand pine scrub will likely succeed to xeric oak/hickory scrub.
Example: sand pine scrub
Serotinous cones (Pinus clausa)Open after heating by fire, require bare mineral soil for germination
Quiz: What fire regime attributes would you “prescribe” to regenerate the stand?
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
a
a
bbb ba
a
adequate foroverstory restocking
Importance of fire severity: P. clausa seedling recruitment
Senescent
Mature
Severity and stand age/ frequency
Example: Reference Condition- savanna
Directly Fire Frequency Fire Season Area Burned
Indirectly Fire Type Fire Intensity Fire Severity
Fire regime attributes manipulated goalsSavanna Restoration
Low density, mature overstory (BA < 15 m2/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
Successful Prescribed Fire Use = Applied Fire Ecology to Meet Management Objectives
Where to find information? Southern Fire Exchange: hub for
resources http://
southernfireexchange.org/index.html
Start with the basics: General Fire Effects on Plant Communities
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
Plant Adaptations to Fire
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 (?)
Woody plant mortality: multiple mechanisms, time-dependent
Hiers et al. Final Report: JFSP 01-1-3-11
Foliage mortality
02468
1012
Temperature F
Tim
e (m
in)
Woody Plant Mortality- Crowns
Crown scorch (dead foliage) increases as air temperature
increases 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
Woody Plant Mortality- stems
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
Looks Severe…Will everything die?
Nope! That’s the beauty of fire adaptation.
Woody Plant Mortality- Roots
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
Fire-Caused Plant Mortality- effects of fuel and structure
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
Woody Plant Mortality- Secondary effects
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
Woody Plants: Post-Fire Recovery
Sprouting is the recovery mechanism in most hardwoods and shrubs:Roots, root crowns, dormant stem buds, rhizomesSurvival related to depth, locationdependent 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
Managing for Post-Fire Seedling Establishment
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
SummaryEffects on Plants
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
Effects on Animals:General Principles
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
• 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).
Smokey’s great grandson?
The principle way that fire affects fauna is by affecting HABITAT 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
For Wildlife in General, Create Habitat Diversity
Grant Steelman
Example: WILD TURKEY ROTATION PATTERNMixed 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
Putting it all together: when to burn, how?
Seasonal Effects: Dormant Season
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
A few months makes a difference: Wiregrass seed production vs. shrubs (gallberry)
May Burn
August Burn
FIRE SEASON: EFFECTS ON UNDERSTORY, FIRE BEHAVIOR, SUMMER VS. WINTER
Saw palmetto: 80% annual growth in summer
10 mo. post burn
Seasonal Effects: Early Spring
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
Seasonal Effects: Growing Season
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
Seasonal Effects: Growing Season-2 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
Seasonal Effects: Fall
Evergreen trees (pines) & shrubs (including palmetto & gallberry) most susceptible to damage!!!!
Most hardwoods will not be affected
Crown damage, season in southern pines
Fire in Florida
How do we manipulate fire to achieve desired ecological effects? Burn
Prescription Parameters.
What will influence fire’s behavior that will result in specific ecological effects?
1) Weather parameters before, during, and after the burn (Air temp., RH, precipitation, wind)
2) Timing of the burn
3) Ignition patterns
Fire in Florida
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 (subsurface) fuels and affect roots and soil
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
Summary 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
Smokey says, “Burn wisely!”