Hazard Tree Felling Safety Tips

Category: 
Felling Safety
Page Last Modified / Reviewed: 
Oct 2019

 

Felling a hazard tree requires accurate risk assessment and complexity analysis, and demands the sawyer’s full situational awareness.  In all cases, remember to establish and maintain a secure felling area.

Do not bypass hazard trees without taking some action such as felling or establishing a No-Work-Zone.

Degree of hazard varies with tree size, species, and type/location of defect:

  • Stem defects resulting in tree failure, i.e., collapse.
  • Weakened sapwood resulting in loss of control when falling trees & limits solid wood for wedging. 
  • Overhead hazards, i.e., dead or hanging limbs falling on the faller.

Line art of a snag tree with bare branches

Indicators of potential felling hazards:

Dead Limbs: limbs of all sizes and species with decay evident cracking, or loose, hung-up limbs.  Avoid working under overhead hazards.

Witches Broom: caused by mistletoe infection, limbs can grow very large and heavy (200+ lbs.)

Split Trunk: cracked trunk from frost, lightning, or wind. Visible evidence of advanced decay indicates serious weakness where the tree could fail.

Stem Damage: caused by windfall, scarring, fire, machine, and animal damage, as well as heart rot diseases.

Thick Sloughing Bark or Sloughing Sapwood: usually found on dead trees. Loose bark on Douglas fir or loose sapwood on wind snapped cedars can dislodge during falling.

Butt and Stem Cankers: usually found on deciduous trees but can occur on Douglas fir and pine. The infected areas weaken the stem.

Fungal Fruiting Bodies or Conks: found on stems it may indicate massive interior rot 1 – 2 yards above and below conk. Excessive resinosis (resin flow) also indicates heart or root diseases.

Heavy Tree Lean: may be caused by damaged roots or lifting root mats, shallow or wet soils. In some cases, the tree may have corrected itself which can be determined by looking for corrected top growth.

Root Condition: look for any ground cracks around the base of the tree, signs of decay or fungal conks on the roots.

Cat Face:  look for enough solid wood to construct an effective undercut and back cut.

 

Additional Resources

Incident Management Situation Report (IMSR)
Incident Response Pocket Guide (IRPG), PMS 461
NWCG Standards for Helicopter Operations, PMS 510
RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR)
Interagency Standards for Fire and Fire Aviation Operations (Red Book)
Wildland Fire Lessons Learned Center

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