How Arborists Assess Trees After Lightning Strike Damage

The Sunshine Coast is known for its dramatic summer thunderstorms. Between October and March, storm cells regularly roll in from the hinterland and the coast, and tall trees in open paddocks, along ridgelines, in backyards and near beaches are often the highest points in the landscape. When lightning hits a tree, the damage is not always obvious. A tree that looks fine the next morning can be structurally compromised or may decline over the following months. A professional assessment by a qualified arborist is the most reliable way to work out whether a struck tree can be saved, needs remedial work, or must be removed for safety.

Why Lightning Damage Is Often Hidden

Lightning travels through a tree's moisture-rich tissues, particularly the cambium and the layer just beneath the bark. The electrical current heats the sap and water in these tissues almost instantly, which can turn them to steam and cause the bark to split or explode away from the trunk. In other cases, the current passes through the tree https://rentry.co/bn5sbr5t and leaves only a thin, spiralling scar, or no visible mark at all.

Even when the outside looks intact, internal damage can include:

Cracking or splitting of the wood along the trunk or through major limbs
Destruction of the cambium, which carries nutrients and water between roots and canopy
Hollowing or charring of internal heartwood
Root damage where current has travelled into the soil
Weakened attachments where branches join the trunk

Because this damage can progress slowly, a tree may seem to recover for weeks before showing sudden leaf drop, dieback or structural failure. That delay is why a considered, systematic assessment matters.

Step One: Immediate Safety Evaluation

The first priority for any arborist arriving at a lightning-struck tree is safety. Before assessing the tree's long-term prospects, they check for immediate hazards to people and property.

Hanging and Partially Detached Limbs

Lightning can leave limbs hanging in the canopy, held only by strips of bark or fibre. These are known in the industry as widowmakers, and they can fall without warning. Arborists look up into the crown first, identifying any broken or loosened limbs and deciding whether they need to be removed before further work happens below.

Targets and Site Conditions

An arborist considers what is beneath and around the tree: houses, sheds, driveways, power lines, fences, play areas and neighbouring properties. The value and vulnerability of these targets influences how urgently the tree must be made safe. If the tree is near powerlines, the arborist will advise contacting the relevant network provider, as work near live electrical assets requires specific authorisation and procedures.

Fire and Smouldering

Lightning can ignite the inside of a trunk, leaving it smouldering long after the storm has passed. This is especially relevant in dry conditions or in trees with existing hollows. If there is smoke, a burning smell or visible heat, call emergency services before anything else.

Step Two: Visual Assessment of the Whole Tree

Once the immediate hazards are managed, the arborist carries out a detailed inspection from ground level, often supplemented by climbing or elevated work platform access for large or complex trees. They examine the tree from root zone to crown tip.

The Trunk

The arborist looks for the lightning's path, which may appear as a vertical or spiral strip where bark has been blown off, exposing pale wood. They assess how wide and deep this wound is, whether it has penetrated into the sapwood, and whether it extends around a large portion of the trunk circumference. A wound that girdles most of the trunk significantly reduces the tree's chance of survival because the transport tissues are interrupted.

The Crown

Foliage condition gives early clues. Scorched, wilted or browning leaves, sudden dieback in a section of the canopy, and fresh splits in the branch structure are all signs of damage. The arborist compares the struck tree's canopy density and leaf colour with nearby healthy trees of the same species.

The Root Zone and Soil

Lightning often travels down the trunk and out through the roots. Signs of root involvement include cracked or heaved soil, scorched ground, gaps opening around the base, and a tree that has begun to lean or shift. Root damage is particularly concerning because it undermines stability, and on the Sunshine Coast, where sandy coastal soils and saturated ground after storms are common, anchorage can already be limited.

Step Three: Detailed Structural and Internal Testing

Where visual inspection raises concerns, or where the tree is of high value or close to people and buildings, arborists may use additional methods to evaluate internal condition.

Sounding with a mallet: Tapping the trunk and listening for hollow or dull tones that suggest internal decay or separation of wood layers.
Resistance drilling: A fine drill bit measures the density of wood as it passes through the trunk, revealing cavities and soft or decayed zones.
Sonic or tomographic testing: Sound waves are used to map internal wood condition without causing significant damage.
Probing cracks: Gently measuring the depth and extent of splits to determine if they are superficial or run deep into the structural wood.

These tools give an evidence-based picture of the tree's remaining strength, which is far more reliable than judging by appearance alone. Many arborists also follow a recognised risk assessment framework, such as the Tree Risk Assessment Qualification (TRAQ) approach or the Quantified Tree Risk Assessment (QTRA) method, to weigh the likelihood of failure against the consequences.

Step Four: Considering Species, Age and Overall Health

Not all trees respond to lightning in the same way. The arborist considers several biological factors when predicting recovery.

Species Tolerance

Some species cope better with injury than others. Trees with strong wound-response abilities may seal over damaged areas and continue to thrive, while others decline quickly once the cambium is breached. Smooth-barked eucalypts, native figs, palms, pines and other common Sunshine Coast species all behave differently, and an arborist familiar with local species can draw on that knowledge when forming a recommendation.

Age and Vigour

A young, vigorous tree has more energy reserves to compartmentalise damage and regrow tissue. An old or already stressed tree, perhaps affected by drought, root disturbance, disease or earlier storm damage, has fewer resources to recover.

Pre-Existing Defects

Lightning often exposes weaknesses that were already present, such as co-dominant stems, included bark, old cavities or previous poor pruning cuts. The arborist assesses whether these combine with the new damage to increase the likelihood of failure.

Step Five: Deciding on a Course of Action

After gathering all this information, the arborist presents the options. In general, outcomes fall into three categories.

Retain and monitor: If damage is minor and the structure is sound, the tree may simply be watched over the following months for signs of decline.
Remedial pruning and care: Broken limbs are removed with clean cuts, torn bark is carefully trimmed back, and the canopy may be reduced to lower the load on a compromised structure. Watering, mulching and appropriate fertilisation may be recommended to help the tree recover.
Removal: If the trunk is split, the root system is compromised, major portions of the cambium are dead, or the tree poses an unacceptable risk to people or property, removal is the responsible option.

It is worth noting that a tree which looks like it might survive can still be dangerous. The arborist's role is to balance the desire to preserve a valued tree against the practical reality of safety.

Aftercare and Ongoing Monitoring

If the tree is retained, recovery is a long process. Over the next 12 to 24 months, the arborist may recommend follow-up inspections to check for:

delayed canopy decline, new cracks opening as the wood dries, fungal fruiting bodies at the base or on wounds, insect or borer activity, and changes in lean or soil movement around the roots. Trees weakened by lightning are more susceptible to pests and decay organisms, so early detection of secondary problems gives the best chance of intervention.

Good aftercare practices include keeping the root zone mulched with organic material, avoiding soil compaction and construction activity near the tree, providing deep watering during dry spells, and avoiding heavy fertiliser applications that can stress an injured tree. Wound dressings and paints are generally no longer recommended, as current arboricultural practice favours allowing the tree to compartmentalise damage naturally.

Local Regulations on the Sunshine Coast

Before removing or heavily pruning a tree, property owners on the Sunshine Coast should check whether the tree is protected under local government rules or state vegetation laws. The Sunshine Coast Council applies local laws and planning scheme overlays that can protect significant trees, vegetation in environmental areas, and trees in certain zones. Emergency exemptions often exist where a tree poses an immediate danger, but the requirements and evidence needed can vary. A qualified arborist can help property owners understand the rules, document the damage with photographs and a written report, and support any application or notification to council. Always confirm current requirements directly with council, as regulations can be updated.

Protecting Trees from Future Lightning Strikes

It is not possible to make a tree completely safe from lightning, but valuable specimen trees can be protected with a properly designed lightning protection system. These systems use copper conductors installed along the trunk and into the ground to carry current safely away from the tree's tissues. They must be designed and installed by competent specialists and inspected regularly, because the system can be affected by tree growth and corrosion. For heritage trees, large shade trees near homes, or trees of cultural or ecological importance, this investment can be worthwhile.

Regular tree health inspections, structural pruning and good soil management also improve a tree's resilience to storm events in general, including wind and heavy rain, which often accompany lightning.

When to Call an Arborist

Contact a qualified arborist as soon as it is safe to do so if you notice any of the following after a storm: bark peeled or blown off the trunk, a fresh vertical or spiral scar, split trunks or limbs, scorch marks, a burning smell, sudden leaf wilting, soil disturbance around the base, or a tree that appears to lean differently than before. Keep people, pets and vehicles away from the area until the tree has been inspected.

Choosing an arborist with recognised qualifications (such as AQF Level 3 or higher in arboriculture), appropriate insurance and local experience gives you confidence that the assessment is accurate and the recommendations are sound. A thorough post-strike evaluation protects your family, your property and, where possible, the trees that make the Sunshine Coast such a beautiful place to live.

Sunshine Coast Tree Removal Experts

Unit 5/12 Kelly Ct, Buderim QLD 4556

(07) 4144 9008