Intro
Trees add comfort, shade, and beauty to homes, yet even healthy trees can develop issues. A tree risk assessment by arborists evaluates how likely a part of the tree is to fail, what it could strike, and the consequences, so you can act wisely and retain the tree when safe.
What Risk Means
Risk is an evidence-based estimate that combines the likelihood of failure, the likelihood of impact, and the severity of consequences. Many certified arborists follow the methodology taught in the ISA Tree Risk Assessment Qualification (TRAQ), guided by ANSI A300 and ISA Best Management Practices. Results are expressed as Low, Moderate, High, or Extreme. No tree is risk-free. The aim is to lower the likelihood of failure and the potential impact to a tolerable level for the specific site based on use and consequences.
What Arborists Typically Look For
Arborists read a tree from the ground up and consider the whole system, not just a single defect.
Roots And Soil
Red flags include soil lifting or cracks that show movement, cut or decayed roots near hardscapes or trenches, buried root collars (bark set below grade), which encourage decay and reduce oxygen at the base, and girdling roots that constrict the trunk. Shallow, compacted, or very dry soils reduce anchorage, raising wind risk even when the crown looks sound.
Trunk And Lower Stem
Concerning signs include fresh cracks, elongated seams, cavities, bulges that suggest internal separation, and fungal fruiting bodies that indicate decay. Co‑dominant stems with included bark can form weak unions because the fibres do not interlock well. Where evidence justifies it, specialized tools can help confirm how much sound wood remains.
Crown And Branches
Arborists look for large deadwood, broken or hanging branches, water sprouts from past topping, long lever-like limbs with heavy end weight, and unions where branch bark is folded inward. Branch spacing and attachment affect how loads move.
Targets And Occupancy
A defect matters most when people, vehicles, or structures are within reach of a falling part. Assessors consider how often an area is used through the day and season. Small site changes, like shifting seating a few metres, can sometimes lower risk more than cutting wood.
Tree History And Species Behaviour
Construction injury, grade changes, drought, and topping weaken structure. Species traits matter too. Poplars and willows may carry long, heavy limbs. Fruit trees can overload in good crop years. Interior conifers such as ponderosa pine have long limbs that collect wet snow. Patterns guide the inspection, but each tree is judged on its own site.
Regional Factors to Consider
Kelowna and nearby communities see hot, dry summers, gusty valley and lake winds, and occasional heavy, wet snow in spring or autumn. Shallow, stony slopes can limit rooting depth and increase exposure. Trees near recent wildfire areas may decline as hidden damage shows. Irrigation during drought also influences root health and stability. These factors change how an arborist interprets defects and sets monitoring intervals.
How Risk Ratings Guide Action
If likelihood is low and occupancy is rare, monitoring may be enough. If both likelihood and consequences are high, timely action is prudent. The best outcomes often pair small changes to the tree with small changes to the site.
Practical Ways Arborists Reduce Risk
- Structural pruning: Reduces end weight, removes dead or defective parts, and improves branch spacing so the crown handles wind and snow with less stress.
- Cabling and bracing: Adds support across weak unions or long limbs; it reduces movement but does not make a tree fail‑proof and needs periodic inspection.
- Soil care and watering: Mulch and better soil structure help roots thrive in the topsoil where most fine roots live; correct irrigation supports anchorage and recovery.
- Target management: Small site tweaks lower risk without heavy pruning, such as moving furniture, redirecting a path, or a seasonal no‑parking zone under a monitored limb.
- Monitoring and re‑inspection: Schedule checks after storms, after construction, and across seasons to track trends; large trees near busy areas benefit from annual reviews.
- Removal of dangerous Tree: If risk cannot be reduced to a tolerable level for the site, removal may be the safe choice.
Clear Signs To Call Right Away
- New lean after wind or rain
- Fresh cracks in the trunk or at a main union
- Soil lifting or cracking around the base
- Large broken or hanging limb over driveways or play areas
- Fire damage that has reached the trunk or main roots
Common Myths, Clarified
- Healthy‑looking trees can still fail
- Topping does not make a tree safer
- Cables reduce movement but do not guarantee safety
- Fungi on bark do not always mean removal
Protect Your Home With Microbe Tree Service
If you are in Kelowna, Vernon or neighbouring communities, schedule a tree risk assessment with our certified arborists. We will create a clear, practical plan to reduce risk with a retention-first approach that keeps trees where feasible. When tree removal is the safer choice, we explain why and outline next steps.
