Hazard Trees

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Hazard Trees
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Hazard Tree
has a structural defect that may cause the
tree or a portion of the tree to fall on someone
or something else of value. --NADF
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Hazard Tree
has a structural defect that may cause the
tree or a portion of the tree to fall on someone
or something else of value. --NADF
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Hazard Tree
has a structural defect that may cause the
tree or a portion of the tree to fall on someone
or something else of value. --NADF
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Hazard Tree
has a structural defect that may cause the
tree or a portion of the tree to fall on someone
or something else of value. --NADF
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Points to consider
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Points to consider

• Tree must have potential for failure

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Points to consider

• Tree must have potential for failure
• Must have proper environment for failure

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Points to consider

• Tree must have potential for failure
• Must have proper environment for failure
• Must have a target

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Points to consider

• Tree must have potential for failure
• Must have proper environment for failure
• Must have a target
• Nearly every tree has some potential to fail.
  Complete tree safety could not be attained
  without removing most trees. -- Harris et
  al. (1999) (Its a matter of degree of risk.)

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What to assess?
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What to assess?

• Top and crown

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What to assess?

• Top and crown
• What is the species?

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What to assess?

• Top and crown
• What is the species?
• Any dead limbs?

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Photo courtesy of Ron Smith
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What to assess?

• Top and crown
• What is the species?
• Any dead limbs?
• Any decayed limbs?

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What to assess?

• Top and crown
• What is the species?
• Any dead limbs?
• Any decayed limbs?
• Leaners recent lean or whole lifetime?

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What to assess?

• Top and crown
• What is the species?
• Any dead limbs?
• Any decayed limbs?
• Leaners recent lean or whole lifetime?
• Overall vigor

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What to assess?

• Top and crown
• Trunk

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What to assess?

• Top and crown
• Trunk
• Forks ...

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What to assess?

• Top and crown
• Trunk
• Forks ...
• Balance

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What to assess?

• Top and crown
• Trunk
• Forks ...
• Balance
• Wounds and decay

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Photo courtesy of Edward L. Barnard, Florida
Department of Agriculture and Consumer
Services www.forestryimages.org
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Photo courtesy of Ron Smith
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Decay detection tools ...
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What to assess?

• Top and crown
• Trunk
• Forks ...
• Balance
• Wounds and decay
• How much wood is needed to maintain strength?

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What to assess?

• Top and crown
• Trunk
• Forks ...
• Balance
• Wounds and decay
• How much wood is needed to maintain strength?

A tree should have gt1 sound wood for each 6 of
diameter at every height OR gt2 of sound wood for
every 6 of diameter if there is an opening that
is lt30 of the stems circumference
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What to assess?

• Top and crown
• Trunk
• Roots

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What to assess?

• Top and crown
• Trunk
• Roots
• Signs of root decay

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Photo courtesy of Edward L. Barnard, Florida
Department of Agriculture and Consumer
Services www.forestryimages.org
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What to assess?

• Top and crown
• Trunk
• Roots
• Signs of root decay
• Severed roots

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Photo courtesy of Ron Smith
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What to assess?

• Top and crown
• Trunk
• Roots
• Signs of root decay
• Severed roots
• Girdling roots

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What to assess?

• Top and crown
• Trunk
• Roots
• Signs of root decay
• Severed roots
• Girdling roots
• Unstable rooting / Soil failure

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Photo courtesy of Robert L. Anderson, USDA Forest
Service www.forestryimages.org
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Fixing hazard trees
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Fixing hazard trees

• Prune out dead and dying branches

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Fixing hazard trees

• Prune out dead and dying branches
• Move the target!

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Fixing hazard trees

• Prune out dead and dying branches
• Move the target!
• Cabling and bracing

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Conclusions
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Conclusions

• All trees are potential hazard trees its a
  matter of degree of risk

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Conclusions

• All trees are potential hazard trees its a
  matter of degree of risk
• Physical defects combine with weather occurrences
  to cause trees or branches to fall

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Conclusions

• All trees are potential hazard trees its a
  matter of degree of risk
• Physical defects combine with weather occurrences
  to cause trees or branches to fall
• Without a target, the tree is not considered a
  hazard