Tree health assessment: method and duty of care

A tree is a living thing that beautifies the city, cools the air and shelters biodiversity. It is also, for its manager, a responsibility: a branch that gives way or a tree that falls can injure. The health assessment is the tool that reconciles these two realities, tracking the condition of trees to protect both the asset and public safety.

Why assess your trees

The owner of a tree, public or private, is liable for any harm it might cause. That liability is judged against the monitoring put in place: a manager who inspects their trees regularly and documents their condition demonstrates due diligence. Conversely, a lack of follow-up counts against them in the event of an accident. Assessing is therefore as much about protecting the public as protecting yourself.

The visual inspection method

The basic assessment rests on a visual examination of the tree, often called VTA (Visual Tree Assessment). The observer works up the tree from the collar to the crown, looking for signs of weakness that betray a mechanical defect or a disease. This non-destructive approach is enough to flag most at-risk trees and to decide which ones warrant deeper expertise.

Warning signs

• wood-decay fungi at the base or on the trunk;
• cavities, cracks or included bark in the forks;
• deadwood in the crown or hung-up branches;
• an unbalanced habit, a recent lean or heaving of the ground;
• sparse or yellowing foliage, or slowed growth.

Three levels of expertise

The visual inspection is the first level. Where doubt remains, a deeper assessment turns to instruments: probing, pull tests, sonic tomography to gauge the internal soundness of the wood without felling the tree. The third level, rarer, involves advanced instrumented measurements. The aim is to fell only what must be felled, grounding the decision in evidence rather than giving in to the precautionary principle.

Inspection frequency

Not all trees need the same attention. A young, vigorous tree in open country is inspected less often than an old specimen overhanging a playground or a busy road. Inspection frequency is adjusted to age, species, condition and above all the target: the more people around the tree, the closer the monitoring must be.

From assessment to action

An assessment is only worth as much as the action that follows: pruning, deadwood removal, bracing, making safe, or felling as a last resort. Each recommendation must be planned, carried out and recorded. It is this loop, from finding to documented action, that makes for serious management, not the isolated assessment.

Remarkable trees

Some specimens stand out by their age, size or history: these are the remarkable trees. They deserve special attention, both for their heritage value and because their age often comes with fragilities. Identifying them in the inventory, monitoring their condition more closely and documenting the care given to them helps preserve them as long as possible, while managing the risk an old specimen can represent.

Anticipating pests and climate

Tree stock faces new threats: emerging pests and diseases, repeated drought and heatwave episodes. Regular monitoring makes it possible to spot dieback early, to isolate a pest outbreak before it spreads and to adapt species choices for future planting. The data collected today informs the decisions of an asset that will have to adapt to climate change.

Tracking your trees with KARTES

KARTES records each tree as a geolocated record: species, dimensions, health condition, recommendations and intervention history. Inspections are captured in the field, photo included, even offline. You track at-risk trees, plan interventions and keep timestamped proof of every visit, from the survey to the dashboard. Monitoring stops being a pile of scattered notes and becomes continuous, defensible follow-up.

Key points

• The manager is liable for harm caused by their trees, in proportion to their monitoring.
• The visual inspection (VTA) flags most at-risk trees.
• Inspection frequency is adjusted to condition and footfall.
• Geolocated, dated follow-up makes management diligent and defensible.