Fire Ecology

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Fire Ecology Fire Effects

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Objetives

• Define fire ecology.
• Describe the various orders of fire effects.
• Identify the fire-related adaptations of plants
  animals.
• Understand the fire regime concept.
• List the components of a fire regime

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Definición

• Fire Ecology is a branch of ecology that focuses
  on the origens of fire and its relation to the
  environment, both physical and biological.
• The study of fire that affects a more or less
  natural environment falls within the scope for
  fire ecology.

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Considerations

• Fire is a natural process that frequently
  operates as an integral part of the ecosystem in
  which it occurs.
• In other situations, fire can be compared to
  other physical disturbances like droughts,
  floods, and tropical cyclones that directly
  impact organisms.
• Human activities can greatly alter the role of
  fire in either instance.

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Considerations continued

• A fire is not usually isolated event, but rather
  is a repeating event for a given site.
• The behavior and effects of a fire depend on the
  existing conditions at the time of the fire and
  the historical conditions of the site.

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Considerations continued

• The ecological effects of fire can be extremely
  complicated.
• Fire should not always be seen as a catastrophic
  event.
• To understand fire effects it is necessary to
  consider the fire

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Levels or categories of fire effects

• First Order Fire Effects effects evident
  immediately post-fire.
• 2nd Order Fire Effects Effects that appear
  sometime after the fire and may be related to
  other environmental factors.
• 3rd Order Fire Effects those effects that
  result from a fire regime rather than from a
  single fire.

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The role of fire in ecosystems

• There are ecosystems and species that need fire.

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The ecological role of fire
.and fire generates a diversity of habitats and
vegetation mosaics that favor many different
species.
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The Role of Fire in LAC Ecosystems

• Fire-dependent require fire

• Fire-sensitivefire detrimental, but
  biodiversity may depend of fire disturbances
  

Fire-independent fuels not available to burn
and/or limited ignitions
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Fire-sensitive ecosystemstropical/subtropical
dry to wet forests
Second burn
1st Burn
Invasive species/flammability/microclimate
feedback
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Retroalimentación de microclima
Deforestación y aumento en igniciónes
Retroalimentación de flamabilidad
Vegetación Boscosa
Pastizal/ Sabana
Fuego
Gramináceas Introducidas
Fire-mediated forest to non-native grass positive
feedback cycle.
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Adaptations of plants in fire-dependent
ecosystems
Thick protective bark of tree and shrub species.
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Adaptations of plants
Capacity to survive fire as a seedling
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Adaptations of plants
Height, growth form and structure
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Adaptations of plants
Capacity to release seeds after fire
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Adaptations of plants
Seed dispersal and regeneration capacity from
surrounding unburned areas.
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Plant adaptations
Flowering responses
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Flowering response
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In prairies, savannas other grasslands, high
ground cover diversity is maintained by frequent
fires and variation in burn season and fire
intensity.
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Savanna in Paraguay
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Plant adaptations
Resprouting capacity
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There are some species that can resprout its
canopy after a crown fire.
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Plant adaptations Flammability
February 2005
July 2005
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Plant morphology and flammability
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Plant adaptations
Heat stimulated regeneration
Crescentia cuejete (Jícaro)
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Fire effects on animals their habitats

• Direct effects--the fire kills individual animals
• Indirect effects--exposes individual animals to
  predation, removes cover, destroys food supplies
• Habitat effects--fire may be necessary to
  maintain habitat, create nesting sites, stimulate
  food sources

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In many cases, animals in fire-maintained
ecosystems, have behavioral adaptations to fire

• Underground hiding places or nesting refugia
• Will re-nest
• Escape hide in unburn areas
• Re-populate from unburned areas

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Bahamas parrot nests in solution holes in
limestone in frequently burned pine
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The use of prescribed fire in fire-dependent
habitats but with species that are
fire-sensitive, the key is not to burn the entire
habitat at one time or in the same season
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Fire effects on soils

• Surface fires in fire dependent ecosystems
  usually do not adversely affect soils.
• Mineral soil is a poor conductor of heat. Roots,
  soil fauna and microrrizha are not affected
  because the heat does not penetrate.
• There is very little erosion after a surface fire
  because the root systems are intact and species
  respout.

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Fire effects on soils

• Is there a loss of nutrients during a fire? N,
  P, K
• The presents of ash changes soil pH that
  facilitates the growth of nitrogen fixing
  blue-green
• Legumes and other nitrogen fixers are common in
  fire-dependent ecosystems and early successional
  ecosystems.
• In fire-dependent ecosystems the root systems are
  adapted to recapture nutrients released from a
  fire.

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Fire effects on the climate
True or false?
A pine forest or savanna that is maintained by
prescribed fire does not result in an increase in
atmospheric carbon over the long
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Questions?