Hazard Tree Identification
Some common tree deficiencies which contribute to potential felling hazards:
Weak Limbs: limbs of all sizes and species with decay evident cracking, loose, hung-up, or fire damaged limbs. Avoid working under overhead hazards.
Weak Tops: split/schoolmarm tops that could have weakened unions, fire weakened tops, rotten or dead tops.
Witches Broom: caused by mistletoe infection, limbs can grow very large and heavy (200+ lbs). Can contribute to uneven weight distribution.
Split Trunk: cracked trunk from frost, lightning, or wind. Visible evidence of advanced decay indicates serious weakness where the tree could fail. May increase wood fiber tension contributing to barber chair potential.
Stem Damage: caused by windfall, scarring, fire, machine, and animal damage, as well as heart rot diseases.
Cat Face: look for enough solid wood to construct an effective undercut and back cut. Complexity increases when desired felling direction is different than that of the cat face.
Thick Sloughing Bark: usually found on dead trees. Loose bark, particularly on Douglas firs, can injure sawyers.
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 may indicate massive interior rot. Excessive resinosis (resin flow) also indicates heart or root diseases.
Heavy Tree Lean: look for any ground cracks around the base of the tree. 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: weakened roots may reduce felling control. Signs of decay or fungal conks on the roots, or fire weakened roots.
Species Consideration: consult local experts for species deficiencies particular to local areas. A good habit is to observe overall tree stand health wherever you’re working.
Felling a hazard tree requires accurate risk assessment and complexity analysis and demands the sawyer’s full situational awareness. Do not bypass hazard trees without taking some action such as felling or establishing a No-Work-Zone.
Discuss indicators of tree defects specific to your local area.
- 10 & 18 Poster, PMS 110-18
- 10 Standard Firefighting Orders, PMS 110
- 18 Watch Out Situations, PMS 118
- Interagency Standards for Fire and Fire Aviation Operations (Red Book)
- NWCG Incident Response Pocket Guide (IRPG), PMS 461
- NWCG Standards for Helicopter Operations, PMS 510
- RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR)
- Wildland Fire Lessons Learned Center
Have an idea or feedback?
Share it with the NWCG 6MFS Subcommittee.