PiCUS TreeMotion Sensor — Dynamic Wind Monitoring
Urban Tree Management carries out dynamic wind monitoring using the PiCUS TreeMotion Sensor — the established professional dynamic monitoring system in arboricultural use. For trees that cannot safely be pull tested, dynamic monitoring records the tree's actual response to real wind events — producing a stability assessment based on real-world performance. Completely independent from any tree surgery contractor.
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Tree Stability Testing
What Is Dynamic Wind Monitoring?
High-precision inclination sensors are attached to the tree at the root collar and stem, recording continuously at 20 readings per second for one to two weeks. The data correlates actual wind loading with actual tree response — showing how the tree moves under the loads it actually experiences in its location.
Unlike static pull testing — which applies a controlled artificial load — dynamic monitoring applies no artificial load at all. The sensors simply record what is already happening. This is what makes dynamic monitoring the correct method for trees where an artificial pull test load would be unsafe.
Why Dynamic Monitoring Is Essential for Decay-Affected Trees
Where significant structural root decay is confirmed — Meripilus giganteus, Kretzschmaria deusta, or advanced Ganoderma — the root plate is already structurally compromised. Applying a static pull test load to a tree in this condition carries a real risk of triggering failure during the test itself.
Dynamic monitoring eliminates this risk entirely. The sensors record the tree's response to natural wind without applying any additional load.
Pathogens that require dynamic monitoring rather than pull testing:
- Meripilus giganteus — giant polypore — rapid basal and root rot, frequent catastrophic root plate failure
- Kretzschmaria deusta — brittle cinder — soft rot of base and roots, brittle ceramic-like fracture without warning
- Advanced Ganoderma spp. — where root plate decay is confirmed and significant
- Armillaria spp. — honey fungus — where basal and root decay is advanced
- Inonotus dryadeus — oak bracket — where root plate integrity is materially compromised
- Phaeolus schweinitzii — velvet roll-rim — where root and butt rot is advanced
Where a pathogen is present but decay extent is uncertain, Arbotom tomography and Resistograph R650 investigation is carried out first.
When Dynamic Monitoring Is the Right Method
Once the tree's response has been measured the DynaTim data can model the effect of a proposed crown reduction on stability — quantifying exactly what level of reduction would bring the safety factor to an acceptable level. This often supports retention rather than removal.
When Static Pull Testing Is Not Appropriate
- Confirmed structural root decay — Meripilus, Kretzschmaria, or advanced Ganoderma
- Restricted access locations — busy roads, paved courtyards, no clear anchor point
- Veteran and heritage trees where artificial loading is unacceptable
- TPO and conservation-restricted trees where ground disturbance is not permitted
- Trees with strongly asymmetric crowns where a single-direction pull test is inadequate
- Construction monitoring — watching stability change in real time during ground works
- Long-term monitoring contracts for local authorities, historic estates, and infrastructure clients
- Post-storm assessment where root movement is suspected
How Long Does Monitoring Take?
Sensors remain on the tree for one to two weeks. Useful wind data requires gusts above approximately 28 mph for at least two hours. In most North West locations this is achieved within the standard monitoring window. Where calm weather extends the period Urban Tree Management advises the client before any additional cost is incurred.
What the Report Contains
- Visual tree assessment
- Pre-monitoring inspection confirming dynamic monitoring was appropriate
- Methodology — sensor specification, placement, monitoring period
- Time-series data — tree response correlated with wind speed throughout monitoring
- Stability assessment under recorded loading conditions
- Discussion — whether response indicates acceptable or unacceptable stability
- Management recommendation
- Limitations including weather conditions during monitoring
Suitable for planning, insurance, legal proceedings, and duty of care documentation.
FAQ
Why can't a tree with root decay be pull tested?
Where Meripilus, Kretzschmaria, or advanced Ganoderma is present the root plate is already compromised. Applying a pull test load risks triggering failure during the test. Dynamic monitoring applies no artificial load — only recording how the tree responds to natural wind.
How long do the sensors stay on the tree?
Typically one to two weeks. Urban Tree Management advises if an extension is needed before any additional cost is incurred.
Can dynamic monitoring be used for long-term monitoring?
Yes — particularly suited to long-term monitoring of significant trees where ongoing stability evidence is required. Urban Tree Management provides long-term monitoring programmes for local authorities, historic estates, and infrastructure clients.
Can you combine dynamic monitoring with decay detection?
Yes — where a tree requires both, Urban Tree Management combines all instruments on the same investigation producing a single integrated report.
PiCUS TreeMotion Sensor Dynamic Wind Monitoring — North West & Nationwide
Urban Tree Management carries out PiCUS dynamic wind monitoring for trees with confirmed root decay, restricted access locations, veteran trees, and long-term monitoring programmes.
Get in contact with our highly experienced and personable team today, to discuss your requirements and to obtain your zero obligation quotation.
