Burn Baby Burn! Prescribed Burning as a Silvicultural Method

1
Burn Baby Burn!Prescribed Burning as a
Silvicultural Method

• Dee Asbury Erin Bodine
• Math 164 Scientific Computing
• 29 April - 2003

2
Motivation

• History of wildfire suppression
• Smokey-the-Bear Effect
• Only you can prevent forest fires!
• Ideology any forest fire is BAD!
• Shift of control burn
• Suppress wildfires
• Use control or prescribed burns to simulate
  natural forest cycles
• Maintenance of forest diversity
• Want to maintain a balance between the various
  tree populations if a forest
• Many tree species suffer without fire
• Ground litter too deep for shallow root trees
• Fire replenishes nutrients in top soil
• Seeds remain dormant, fire releases seeds from
  cones

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The Questions

• How can prescribed burns be used to maintain
  forest diversity?
• How will forest equilibrium be affected by fire
  suppression?
• Can we find an optimal burn frequency to yield
  desired forest dynamics?

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The BiologyA Hardwood and Pine Tree Forest

• Hardwoods Fire Haters!
• Hardwoods have a deep root system
• Fire has phoenix effect on hardwoods
• Spread rapidly
• Pine Trees Fire Lovers!
• Pine trees have a shallow root system
• Fire causes pine cones to open
• Pine trees have greater fire tolerance
• Dynamics
• Hardwoods will crowd out pine trees!

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The Model An Overview

• The model uses time dependent transition matrices
  to calculate
• annual tree populations
• forest diversity
• The three transition matrices are
• growth (G)
• replacement (R)
• death (D)

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The Model Growth Matrix

• Example of a growth matrix
• Transition matrix models four height classes

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The Model Replacement Vector

• Example of a replacement vector
• All replacements occur in smallest height class

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The Model Death Matrix

• Example of a death matrix
• Transition matrix models four height classes

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Results Maximum Fire Suppression
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Results Control Burn
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Results Control Burn
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Results Answers to the Questions

• How can prescribed burns be used to maintain
  forest diversity?
• Prescribed burns, at the appropriate frequency,
  can maintain the desired forest diversity.
• How will forest equilibrium be affected by fire
  suppression?
• In the pine/hardwood forest frequent fires will
  maintain a pine forest, infrequent fires will
  maintain a hardwood forest.
• Can we find an optimal burn frequency to yield
  desired forest dynamics?
• Close! Populations are slowly declining over
  time.

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Extensions

• Model carrying capacities more accurately.
• Model effects of fire frequency on local
  wildlife.
• Model effect of fire frequency on biomass instead
  of tree populations.
• Add dynamics of shrubs and other flora.
• Add effects of other methods of silviculture
  (i.e. logging and thinning).