Tree Diagnosis & Risk

Most tree failures are not sudden. They begin inside the wood, where decay can hide behind a healthy-looking crown. This shelf collects articles on how trees are diagnosed and how risk is judged, from methods that need nothing more than eyes, hands and a mallet to instruments that read the inside of a trunk. I write from my work as an arborist in Tokyo.
The field-method article explains how Japanese arborists read decay before any machine arrives. Two articles then go one level deeper into instruments. The first explains how a resistograph works, using the IML-RESI PowerDrill: it records resistance along the path of a thin needle and nothing more, and that limit is the reason the tool is useful. The second explains sonic tomography with the ArborSonic 3D, which measures how long a stress wave takes to cross the trunk and turns that single measurement into a picture. A case article shows the result in practice, with ropework and sonic tomography used together on a temple's sacred trees in Tokyo.
Two pieces compare systems of judgement. One sets visual tree assessment (VTA) beside Japan's jumoku-i approach, and the other explains what a jumoku-i is, how the certification works and how it differs from ISA arborist certification.
Related articles cover how trees seal wounds after pruning, and what happens when ageing street trees fall in large numbers.
The shelf is for tree owners, managers and arborists who want to know what each method can and cannot show. These three are the clearest way in.
Start here

How to Read Tree Decay Without Technology: Japanese Field Methods
How a Resistograph Works: Reading the IML-RESI PowerDrill in Japan’s Tree Diagnosis
How Sonic Tomography Works: Reading the ArborSonic 3D in Japan’s Tree Diagnosis