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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

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Leda N. Kobziar School of Forest Resources and Conservation University of Florida


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    1. Ecological Effects- short version Chapter IX: Interagency Prescribed Fire Training Leda N. Kobziar School of Forest Resources and Conservation University of Florida

    2. 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

    3. 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 in Florida

    4. 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

    5. Why is fire ecology important in the south?

    6. US Wildfires by Region: 2000-2010

    7. Fire in Florida

    8. Fire in Florida Florida’s Historical Fire Regime: May-June

    9. 12,000+ yrs of Lightning + Anthropogenic Fire Use • 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)

    10. Legacy of anthropogenic and lightning fires • 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). Chris Evans

    11. Repercussions of long-term burning FL Fire Ecosystems • 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

    12. Unsustainable harvesting & fire suppression  forest Degradation: ~3% original forest remaining • Lack of seed sources, regeneration of fire adapted species • Altered soil fertility, pH, texture, mycorrhizae… • Loss of fire-structure dependent wildlife spp. • Closed communities with limited early successional species recruitment • Changes in flammability and fuels structure • Fuel load build-up  larger, less predicable, higher severity, more costly wildfires

    13. In the south, reversing The Legacy of suppression and degradation means using prescribed fire to restore and maintain native ecosystems

    14. 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

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

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

    17. 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!

    18. Fire regimes correspond to the Distribution of FL native ecosystems Shrub Wetland Marsh Bay head Hydric Hammock Pine Flatwoods Low scrub Savanna Mesic Hammock Depth to Water Table (m) Slash pine scrub Sand Pine Scrub Rosemary scrub Rosemary scrub High Pine Oak scrub Xeric Hammock Rosemary Bald Fire Interval

    19. Example: sand pine scrub Without fire sand pine scrub will likely succeed to xeric oak/hickory scrub.

    20. Serotinous cones (Pinusclausa)Open after heating by fire, require bare mineral soil for germination

    21. 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

    22. adequate for overstory restocking Importance of fire severity: P. clausaseedling recruitment Senescent a a a Mature a b b b b

    23. Severity and stand age/ frequency

    24. Example: Reference Condition- savanna

    25. 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 • Directly • Fire Frequency • Fire Season • Area Burned • Indirectly • Fire Type • Fire Intensity • Fire Severity

    26. Successful Prescribed Fire Use = Applied Fire Ecology to Meet Management Objectives

    27. Where to find information? • Southern Fire Exchange: hub for resources • http://southernfireexchange.org/index.html

    28. 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

    29. 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 (?)

    30. Woody plant mortality: multiple mechanisms, time-dependent Hiers et al. Final Report: JFSP 01-1-3-11

    31. 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

    32. 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

    33. Looks Severe…Will everything die?

    34. Nope! That’s the beauty of fire adaptation.

    35. 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

    36. 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

    37. Bark beetle pitch tubes 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)

    38. Woody Plants: Post-Fire Recovery • 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

    39. 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

    40. 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

    41. 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

    42. 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?

    43. The principle way that fire affects fauna is by affecting HABITAT • Cover is temporarily decreased • Microclimateis 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

    44. For Wildlife in General, Create Habitat Diversity Grant Steelman

    45. 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

    46. Putting it all together: when to burn, how?

    47. 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