Tree risk assessment and hazard trees field guide

A tree is only a hazard when there is a target under it

Tree risk assessment is the systematic evaluation of how likely a tree or one of its parts is to fail, how likely the failed part is to hit something that matters, and how bad it would be if it did. Those three judgments combine into a risk rating, and the rating drives one decision: monitor it, mitigate it, or remove it. That is the whole job in one sentence.

A tree is not a hazard on its own. It becomes a hazard when there is a target under it. A structurally poor tree leaning over the empty back corner of a property is low risk, because nothing is there to hit. The same tree, same defect, leaning over an occupied patio is high risk. So assessment is never just about the tree. It is defect plus target plus consequence, weighed together.

That framing changes what you do. Look only at the tree and you condemn sound trees for cosmetic flaws and miss the moderate defect parked over the picnic table. The pruning that keeps a canopy sound and the cabling that holds a weak union together both start here, with an honest read of the tree and what sits beneath it. This is professional judgment, done by a qualified arborist, not a checklist a homeowner runs on a leaning oak.

Why the assessment matters, and why fear is the wrong driver

The reason to assess is consequence. A mature tree part failing onto a person, a car, or a roof is a life-safety and property event, and the owner who has that tree carries a duty of care for it. That duty is not a duty to guarantee no tree ever fails. It is a duty to take reasonable steps to find and manage foreseeable risk. Courts and insurers look for whether a reasonable inspection happened and whether the findings were acted on.

Here is the part that gets lost. The answer to risk is not to cut every flawed tree down. Trees with defects stand safely for decades when the defect is over nothing, or when it is managed. Removing a low-risk tree out of fear costs the owner a mature asset, the shade, the stormwater capture, the property value, and buys almost no safety, because the risk was already low.

So the work is proportionate. Match the response to the rating. A high or extreme risk gets acted on now. A low risk gets left alone or watched. Spend the money where the consequence justifies it, and document that you made the call on purpose, not in a panic.

The risk framework: likelihood times target times consequence

Risk in tree work is the product of three things, and dropping any one of them gives the wrong answer. Risk equals the likelihood that the part fails, times the likelihood that the failed part hits a target, times the consequence if it does. ISA built its method and ANSI A300 Part 9 frames the assessment around exactly these components.

Read it as a chain. A dead limb that is almost certain to fall, so a high likelihood of failure, over a closed-off service yard nobody enters, so a near-zero likelihood of impact, is low risk, because the middle term is small. A small, sound-looking twig over a crowded entrance carries little risk because the consequence term is small even if it drops. The high numbers come when all three line up: a likely failure, a frequently occupied target, and a part big enough to do real harm.

The math is not literal arithmetic you punch into a calculator. ISA uses categories and a matrix, not multiplication. But the multiplication is the right mental model, because it tells you that a single large term cannot carry the rating alone. A tree over nothing is low risk no matter how ugly the defect.

The target sets the risk, so look down first

The target is whatever the tree could hit: people, a house, a car, a road, a power line, a playground, a shed. No target means no risk worth a rating, and that single fact reorders the whole job. The first thing a qualified assessor does on site is look down and around, not up.

What raises the target term is occupancy, how often and how long something or someone is present. A bench used all day, a driveway, a deck, a bus stop under the canopy all push the likelihood of impact up. A back fence line nobody walks, a fallow field, a tree over its own mulch ring all push it down. A target present constantly is not the same as one a person crosses for two seconds a week, and the rating reflects that difference.

This is why you can leave a defective tree standing in one spot and have to act on the identical tree in another. The defect did not change. The target did. Get the target wrong and the whole assessment is wrong, no matter how carefully you read the trunk.

Likelihood of failure: the structural side

Likelihood of failure is the structural question: how likely is this part, or the whole tree, to come apart within the assessment period. It is driven by the defects you can see and the loads the tree carries, weighed against the wood that is still sound. A crack through a major union, a large decay column, a fresh lean with lifted roots all raise it. A clean, well-tapered stem with no visible defect lowers it.

ISA scales this in four steps: improbable, possible, probable, and imminent. Imminent means failure is expected at any time, with or without a wind event, which is its own alarm. The rest are judgments about how the defect behaves under the loads the site actually delivers. A defect that would fail only in a once-a-decade storm is not the same as one already moving on a calm day.

The honest part of this term is that it is a probability, not a verdict. A sound-looking tree can still fail, and a defective one can stand for years. The assessor is estimating odds over a timeframe, which is why the rating is always tied to a re-inspection, not treated as permanent.

Consequence: how bad it is if it lands

Consequence is the severity of the outcome if the part fails and hits the target. The same likelihood of failure means very different things depending on what comes down. A pencil-sized deadwood twig over a sidewalk and the whole stem over a nursery are not the same event, even if both are equally likely to fail.

ISA grades consequence as negligible, minor, significant, or severe. The part's size and the height it falls from drive it, along with what it lands on. A large limb failing onto a parked car is property damage. The same limb onto an occupied car is a different category entirely. This is where the assessor weighs not just the tree part but the value and vulnerability of what it would strike.

Consequence is the term people skip when they fixate on the defect. A big, scary-looking cavity low on a trunk over a lawn may carry a smaller consequence than a modest dead limb high over a play structure, because the dead limb has height and a soft target. Size the consequence to the part and the target together, not to how dramatic the defect looks.

The ISA matrix turns three judgments into a rating

ISA turns the three judgments into a rating with two matrices, not a single formula. The first matrix combines the likelihood of failure with the likelihood of impacting the target to produce a single likelihood of failure and impact, scaled unlikely, somewhat likely, likely, or very likely. The second matrix crosses that result with the consequence to produce the final risk rating: low, moderate, high, or extreme.

The point of the matrix is consistency. Two qualified assessors working the same tree should land on close ratings, because the categories and the crossing are defined rather than felt. Research on assessor agreement shows it is not perfect, which is the honest caveat, but the structured method beats a gut call and gives a defensible record.

Treat the rating as the output that drives the decision, not as a precise score. The exact category names and the matrix crossings are defined by ISA and should be applied by a qualified, TRAQ-trained assessor, not reconstructed from memory on a tailgate.

Match the TRAQ level to the situation

ISA Tree Risk Assessment Qualification, TRAQ, defines three levels of assessment, and the skill is matching the level to the situation rather than always reaching for the deepest or the quickest. The levels are not grades of quality. They are depths of inspection.

Level 1 is a limited visual assessment, a fast look at many trees from one perspective, often from a vehicle, to flag the obvious. Level 2 is a basic assessment, the standard 360-degree ground inspection of one tree, and it is the workhorse most jobs actually need. Level 3 is an advanced assessment, bringing tools and detailed methods to a specific question Level 2 could not answer.

You step up a level when the tree or the target warrants it, and ANSI A300 Part 9 frames the assessment scope this way. A street-tree population gets a Level 1 screen. A specific tree over a building gets at least a Level 2. A Level 2 that finds a large decay column over a target may trigger a Level 3 to quantify it. A qualified arborist chooses the level, and using too shallow a level on a serious defect is one of the real failures in this work.

Level 1: the limited, windshield survey

Level 1 is the limited visual assessment, sometimes called a windshield or drive-by survey. The assessor looks at trees from a single vantage, often from a moving or parked vehicle or along a walk route, scanning for large, obvious problems: a big dead top, a major lean, a failed limb hung up in the canopy, a trunk split. It is built for speed across many trees, not depth on one.

Use it to screen a population: a street, a campus loop, a park after a storm. The output is a triage list, the trees that need a closer look, not a final rating on each one.

A Level 1 cannot see what is behind the trunk or low in the root flare, and it is not meant to. Its job is to find the trees that earn a Level 2, fast, and to flag anything that looks like an immediate problem for same-day attention.

Level 2: the basic 360-degree ground inspection

Level 2 is the basic assessment and the standard most tree risk work is built on. The assessor walks a complete circle around the tree, looks at it from the ground up, and inspects the root flare, the trunk, the major unions, and the canopy from all sides. Simple tools come into play: binoculars for the upper canopy, a mallet to sound the trunk for hollow areas, a probe for cavities, a trowel to check the root collar.

This is the level that produces a documented risk rating using the ISA matrix. It is thorough enough to catch the defects that matter and efficient enough to do at scale on a managed population. Most of the trees that need a real assessment need exactly this one.

The 360-degree part is not a formality. Decay, cracks, and included bark hide on the side you did not walk to, and the lean that looks fine head-on shows its lifted roots from the flank. Skip the full circle and you have done a Level 1 while calling it a Level 2.

Level 3: advanced assessment with tools

Level 3 is the advanced assessment, and it exists for the specific question the basic inspection raised but could not settle. When a Level 2 finds a large decay column, a suspect union, or root loss that could govern the whole tree, Level 3 brings the tools and the time to quantify it.

The methods include decay detection with a resistance-recording drill, a resistograph, sonic or electrical tomography that maps the sound wood across a cross-section, an aerial inspection climbing or lifting into the canopy, and a root-collar excavation with an air spade to see the buttress roots a trowel cannot reach. Static load testing and detailed measurement also live here.

Level 3 is slower and costs more, so you spend it where the decision turns on a number the eye cannot give. It is not the default. A qualified arborist orders it when the consequence is high enough that the extra certainty is worth it, and the tools are interpreted by someone trained on them, because a tomograph in untrained hands produces confident-looking nonsense.

The common defects to look for

The defects that drive failure are a known set, and a qualified assessor checks for each one deliberately rather than waiting for something to jump out. They fall into a handful of families: dead wood, cracks, weak unions with included bark, decay and cankers, root problems, and lean.

The table below is the field scan, not the whole story. Any one of these can range from trivial to severe depending on its size, its location on the tree, and the target beneath it. A small cavity over nothing is noise. The same cavity at a major union over a patio is the assessment.

Dead wood and hangers: the common drop hazard

Dead wood is the most common drop hazard, and the one a Level 1 catches best. A dead limb has no living connection left, so it fails on its own schedule, often on a still day when nobody expects it. The bigger the dead piece and the higher it sits, the more it matters, and a large dead limb over a target is a straightforward call to remove.

Hangers are the related problem: a branch already broken and lodged in the canopy, held by nothing but friction and a stub. Wind or its own weight finishes the job, usually onto whatever is below. After any storm, hung limbs are the first thing to scan for over walks and parking.

Deadwood pruning is the standard mitigation, and it ties straight to the work in the tree pruning and maintenance companion guide. Removing the dead and the hung wood over a target is usually the cheapest, highest-value risk reduction on the tree, and taking dead material out does not harm a healthy tree.

Codominant stems and included bark

A codominant union is where two stems of similar size grow from nearly the same point, and the danger is what grew between them. When the two stems push against each other, the bark turns inward instead of forming a strong, interlocked branch collar. That trapped bark is called included bark, and it is a built-in weak plane. There is no real wood connection across it, so the union splits under wind, ice, or its own weight, often taking half the tree.

The tell is the shape. A strong union is U-shaped with a visible branch collar. A weak one is a tight V with a seam where the bark folds in, sometimes with a ridge of wound wood along the line where the stems are slowly tearing. Two equal leaders with a deep, tight crotch over a target is a defect to take seriously.

Mitigation depends on the tree's value and the rating. On a young tree, pruning to a single leader removes the problem before it sets. On a mature tree worth keeping, a cable between the leaders can reduce the movement that opens the union, which is the subject of the tree cabling and bracing companion guide. Hardware does not cure the union. It buys margin while the target stays put.

Decay, cavities, and the sound-wood rule of thumb

Decay is the loss of sound wood to fungal breakdown, and it matters because a stem holds load with its outer shell, not its center. A tree can carry a sizable hollow and still stand, which is why a cavity alone is not a death sentence. What you are judging is how much sound wood is left, and where.

The field tells are fungal conks or mushrooms on the trunk or root flare, wood that sounds hollow when you tap it with a mallet, soft or punky wood at a probe, and old wounds that opened a path for rot. A conk is worth knowing on sight, because a fruiting body on the outside usually means established decay inside, often more than the opening suggests.

There is a widely cited rule of thumb for hollow stems: concern rises when the sound wood shell is thinner than about a third of the stem radius, often written as a t/R ratio of 0.3, with t the remaining wall thickness and R the stem radius. Treat that as a screening threshold, not a verdict. It assumes a roughly round, centered hollow on an otherwise sound tree, it does not account for open cavities or cracks, and the real call belongs to a qualified arborist, often with Level 3 tools, weighing the species, the loading, and the target. The figure comes from ISA literature and should be applied, not recited.

Root problems: the failure that takes the whole tree

Root problems are the most dangerous defect because they take the whole tree, not a part, and they are the hardest to see. A failure at the stem might drop a limb. A root failure puts the entire tree on the ground, onto whatever is downwind. So the root flare gets the assessor's attention first, not last.

What you look for: soil lifting or cracking on the side opposite a lean, roots cut by trenching, paving, or a grade change, girdling roots that circle and strangle the flare, and fungal fruiting bodies at the base that signal root rot. Construction damage is the quiet killer here. A tree can look full and healthy for years after its roots were cut on one side, then go over in a wind it should have shrugged off, because the anchorage was gone the whole time.

This is where the duty of care gets serious, because the warning signs are subtle and the consequence is the entire tree. New soil heaving at the base is an emergency-grade sign. If the ground around the trunk is cracked or lifted and the tree is over a target, restrict the area and get a qualified arborist on it now, not next week.

A lean: old and adapted, or new and moving

A lean is not automatically a defect. Plenty of trees grew at an angle reaching for light and have stood that way, fully anchored, for their whole lives. The wood and the roots adapted to the load over decades. A long-standing lean with no soil disturbance, on a tree that has built reaction wood to support itself, is usually stable.

The lean that matters is the new one. A tree that was vertical and is now leaning, especially with cracked or heaved soil on the high side of the root plate, is failing at the roots in real time. That is an urgent, often imminent situation, and it reads as a different animal from the old corkscrew oak that has leaned since it was a sapling.

So the question on a lean is never just the angle. It is whether the lean is old and adapted or new and moving. Look at the base. Adapted leans have settled soil and a thickened, buttressed low side. Failing leans have a fresh crack, a lifted mat of roots and soil, and a tree that was not at that angle last year.

Species, site, and history put the defect in context

Species and site put the defect in context, because the same flaw behaves differently on different trees in different places. Some species are known for predictable failures: brittle wood that sheds limbs, weak-wooded fast growers that drop large branches in summer with no warning, species prone to included-bark unions. A qualified assessor carries this local knowledge and weighs it, while treating it as a tendency, not a certainty, because individual trees vary.

Site loads the tree. A specimen that grew in the open in a sheltered yard and is now exposed by the removal of its neighbors faces wind it never adapted to. Wet or compacted soil weakens anchorage. A tree at the top of a slope or the corner of a building catches accelerated wind. History matters too: a tree that has already shed a large limb, or one near recent construction, tells you where to look.

None of this replaces seeing the tree. It is the context that tunes the assessment, and the local failure patterns are something a qualified arborist learns from the trees in that region, not from a table.

Risk runs over a timeframe, so re-assess

A risk rating is not permanent. It describes the tree over a stated assessment period, and outside that window the rating is stale. Trees grow, decay advances, loads change, and a clean tree this year can develop a defect by the next. So every assessment carries a timeframe and a re-inspection interval, and ISA and ANSI A300 Part 9 frame ratings against a defined period rather than forever.

The timeframe is a judgment about how fast the situation can change. A sound tree on a low-traffic site might be set for a multi-year cycle. A tree with an active defect over a frequent target gets a short interval, sometimes months, sometimes a same-season recheck. Storms reset the clock: high wind, ice, or saturated soil can turn a moderate tree into a high one overnight, which is why post-storm inspection is its own trigger.

Treat the interval as part of the recommendation, not an afterthought. An assessment with no re-inspection date is a snapshot that quietly expires, and the owner is left thinking a tree was cleared when the clearance ran out.

The mitigation menu, matched to the risk

Mitigation is the menu of responses between leaving a tree alone and taking it down, and the right one is matched to the rating, the defect, and the value of the tree. Reaching for removal first, or for a cable on a tree that should come down, are both failures of judgment.

The options run roughly from lightest to heaviest. Prune to remove the deadwood and the hung limbs over the target, the cheapest and most common fix, covered in the tree pruning and maintenance companion guide. Reduce the weight on an overextended or defective limb to lower the load it carries. Install a cable or brace to support a weak union on a tree worth keeping, the subject of the tree cabling and bracing companion guide. Restrict or move the target so the consequence drops. Monitor on a short interval when the risk is real but not yet actionable. Remove the tree or the part when nothing lighter brings the risk to a tolerable level.

The art is proportionality. A moderate risk from deadwood over a path is solved by a pruning crew and a morning, not by a chainsaw at the base. Spend the mitigation that fits the rating, document why you chose it, and re-inspect on the interval the defect deserves.

Sometimes you move the target, not the tree

The cheapest mitigation is often the one nobody thinks of: move the target instead of touching the tree. Risk is defect times target times consequence, so removing the target collapses the rating without a single cut. Close the path, relocate the bench, move the parking spaces out from under the canopy, reroute the trail, and a high risk can drop to low because there is no longer anything to hit.

This is the move on a structurally valuable tree you would rather keep. A mature shade tree with a defect over a seating area does not have to come down if the seating area can go somewhere else. The tree stays, the people are safe, and the owner keeps the asset.

It does not work when the target cannot move, a house, a road, a power line. But where it can, it is usually the fastest and least expensive way to manage the risk, and it should be on the table before removal is.

When removal is the call

Removal is the call when the risk is high or extreme and nothing lighter brings it down to a level the owner can accept. A large defect over a target that cannot move, a tree failing at the roots, a hollow stem past what the wood can carry over a house: these are the cases where the honest recommendation is to take it down. When the consequence is severe and the failure is likely, removal is the responsible answer, not an overreaction.

But removal is the last resort, not the first. It is irreversible, it costs the owner a mature asset, and a low-risk tree does not earn it. The failure to avoid is the reflex to remove anything with a visible flaw, which condemns sound trees and spends money on safety that was already there.

The discipline is to exhaust the lighter options honestly first. Can pruning fix it? Can a cable hold it? Can the target move? When the answer to all of those is no and the rating is high, removal is correct, and it should be documented as the considered end of a chain of options, not a panic call.

The report is the record and the liability defense

The assessment that is not written down did not happen, as far as liability is concerned. The report is the record that you looked, what you found, how you rated it, what you recommended, and that the owner was told. When a tree fails and the question becomes whether a reasonable inspection took place, the documented assessment is the defense.

Capture the tree and its location, the target and its occupancy, the defects you found, the level of assessment you performed, the likelihood, the consequence, the final rating, the recommendation, and the re-inspection interval. Photographs of each defect and the target are worth more than paragraphs, because they show the condition on the date you saw it. A field tool such as FieldOS lets the assessor capture the photos, the location, the rating, and the recommendation on site and keep them tied to the tree, so the record exists before the crew leaves.

Write the recommendation as an action with a date, not a vague worry. Remove the dead limb over the patio by a date, re-inspect the cabled union in twelve months, monitor the lean and recheck after the next major storm. A recommendation nobody can act on is the same as no recommendation.

What to document

The record only helps if it captures the factors that drive the rating and the decision. Document the tree, the target, the defects, the rating, and the recommendation, with a date and a photo on each. The table below is the minimum a defensible assessment carries.

A qualified arborist does the real assessment

The real assessment is done by a qualified arborist, and this is the point the whole guide is built around. An ISA Certified Arborist with the Tree Risk Assessment Qualification is trained in the method, the matrix, the defects, and the limits of each. The judgment is built from seeing thousands of trees fail and stand, not from running a list.

This guide explains the framework so an owner or a property manager understands what a good assessment involves and can tell a real one from a guess. It is not a license to rate a hazard tree yourself. A layperson can spot obvious dead wood and call it in. A layperson cannot read a decay column, judge an included-bark union, or weigh species behavior against site loading, and getting those wrong is how people get hurt or how sound trees get needlessly cut.

So the line is firm. Screen and notice, yes. Assess and decide on a real hazard tree, no, not without a qualified arborist. The standards exist because the consequence of a wrong call is measured in injuries and lawsuits, not in a redone worksheet.

The limits: assessment reduces risk, it does not erase it

Tree risk assessment reduces risk. It does not eliminate it, and any assessor who implies otherwise is overselling. Trees are living structures loaded by weather nobody controls, and a sound-looking tree can fail in a storm that exceeds what anyone could foresee. The honest promise is a reasonable, documented effort to find and manage foreseeable risk, not a guarantee.

That is what the duty of care asks for. An owner is expected to take reasonable steps: an inspection program suited to the trees and the targets, action on what is found, and records of both. The duty is reasonableness, not perfection, and the legal standard turns on whether a competent assessment happened and was acted on, which the adopted standards and the local ordinance frame.

So set expectations plainly with the owner. The assessment lowers the odds and creates the record. It cannot promise the tree will never fail. The right posture is a managed program that catches the foreseeable problems and accepts that residual risk remains, because the alternative, removing every tree, is neither sane nor what anyone wants.

A routine inspection program for managed trees

For managed tree populations, a park, a campus, a streetscape, a commercial property, risk work is a recurring program, not a one-time visit. The owner with many trees has a standing duty to inspect them on a cycle suited to the trees and the targets, and a documented program is the practical form that duty takes.

A workable program sets an inspection cycle, often a Level 1 screen across the whole population on a regular interval, with Level 2 assessments triggered for flagged trees and for any tree over a high-value target. It adds event-driven inspections after storms, because high wind, ice, and saturated soil change ratings fast. And it assigns the work to qualified people, so the assessments hold up.

A field tool such as FieldOS helps the program run by carrying the tree inventory, the cycle dates, and the last assessment for each tree, so nothing falls off the schedule and the next due date stays visible. The program that exists only in someone's memory is the program that lapses the year that person leaves.

The records that build a defensible history

The records are what turn a series of visits into a defensible program. For each tree you want a running history: when it was assessed, at what level, what was found, the rating, what was recommended, what was done, and when it is due again. That history is what shows a court or an insurer that the duty was met continuously, not once.

Photographs anchor the record. A dated photo of a defect lets the next assessor see how it has changed, whether a crack opened, whether a decay pocket grew, whether a cable is still sound. The change over time is often more telling than any single snapshot, and it is impossible to reconstruct after the fact if nobody captured it.

A field tool such as FieldOS keeps the photos, the ratings, and the cycle tied to each tree so the record builds itself as the program runs, rather than living in scattered spreadsheets and a glovebox of paper. When the question comes years later about whether a tree was being watched, the answer should be a file, not a memory.

Common mistakes

• Judging the tree without the target, rating the defect while ignoring whether anything is under it.
• Not matching the assessment level to the defect, running a windshield Level 1 on a tree that needs a Level 2 or 3.
• Missing the root and new-lean signs, the subtle defects that take the whole tree.
• Removing low-risk trees out of fear, condemning sound trees for cosmetic flaws.
• Leaving no documented assessment, so there is no record that a reasonable inspection happened.
• Treating a rating as permanent, with no re-inspection interval and no recheck after storms.
• Applying the t/R hollow rule or the matrix from memory instead of as a qualified, TRAQ-trained assessor.

Field checklist

Standards and references

The framework for this work comes from ISA and ANSI. The ISA Best Management Practices for Tree Risk Assessment and the Tree Risk Assessment Qualification, TRAQ, define the components, the assessment levels, the likelihood and consequence categories, and the two-matrix rating. ANSI A300 Part 9 is the American National Standard for tree risk assessment, and it frames the scope, the levels, and what a competent assessment considers.

The specific ratings, the level definitions, and the hollow-stem t/R rule of thumb belong to that ISA and ANSI literature and should be applied by a qualified, TRAQ-trained assessor, not reconstructed from a guide. The category names and the matrix crossings are defined there. Where a number or a threshold drives a decision, work from the current standard and the assessor's training, because the methods are revised across editions.

Local tree ordinances add another layer. Many jurisdictions regulate removal, require a permit, or set protection rules for heritage and street trees, and some require an arborist report to remove a tree at all. Confirm the local ordinance and any permit requirement before removal, and let the qualified arborist's assessment and the adopted standards govern the call. The throughline is plain: assess defect plus target plus consequence, match the TRAQ level to the situation, and have a qualified arborist document the rating and set the re-inspection.

Units and terms

Tree risk work has its own vocabulary, and the terms carry specific meanings that a loose reading gets wrong. These are the ones that matter on a report.

Tree risk assessment

The systematic evaluation of likelihood of failure, likelihood of impacting a target, and consequence, combined into a risk rating

Target

Anything the tree could hit if it fails: people, structures, vehicles, roads, utilities; occupancy sets how often it is present

Likelihood of failure

The chance a tree or part fails within the assessment period, scaled improbable, possible, probable, or imminent

Consequence

The severity if a failed part hits the target, scaled negligible, minor, significant, or severe

TRAQ levels

ISA assessment depths: Level 1 limited visual, Level 2 basic 360-degree ground inspection, Level 3 advanced with tools

Codominant stems / included bark

Two equal stems from one point with bark turned inward at the union, a built-in weak plane prone to splitting

Mitigation

The response that reduces risk: prune, reduce weight, cable or brace, move the target, monitor, or remove

Risk rating

The matrix output, low, moderate, high, or extreme, that drives the monitor, mitigate, or remove decision

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