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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 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 # of Lightning Fire Acres 1986-1997 300 # of Acres (x 1000) 300 250 250 200 200 150 150 100 100 50 50 0 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month # 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) Thousands of yrs of repeated burning ecosystem structure & composition Selected for fire-resistant or firedependent 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 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 Scrub Dry Prairie Mesic Flatwoods Scrubby Flatwoods Wet Flatwoods Glades Marsh Marl Prairie Frequent, 1-3 yrs Variable, 5-30 yrs Frequent, 1-2 yrs Frequent, 1-4 yrs Variable, 5-15 yrs Frequent, 3-10 yrs approx. 2-5 yrs 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 Randy Cyr 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 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 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! 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 Marsh Shrub Wetland Bay head Hydric Hammock Pine Flatwoods Slash pine scrub Sand Pine Scrub Savanna Depth to Water Table (m) Low scrub High Pine Mesic Hammock Rosemary Rosemary scrub scrub Oak scrub Rosemary Bald Fire Interval Xeric Hammock 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 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 Importance of fire severity: P. clausa seedling recruitment Senescent a Mature adequate for overstory restocking a a a b b b b 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 Southern Fire Exchange: hub for resources http://southernfireexchange.org/index.html 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 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 (?) 0 15 2 14 4 13 6 12 10 8 6 4 2 0 12 Time (min) Foliage mortality Temperature F Hiers et al. Final Report: JFSP 01-1-3-11 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 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 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 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 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 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 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). 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 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 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 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 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 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 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 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 specific ecological effects? Fire in Florida 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 (subsurface) fuels and affect roots and soil Fire in Florida 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 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