Tree risk management is full of contradictions. At one extreme, the pro-tree lobby argues that the risk of harm from trees is so low that very little intervention is needed.
At the other extreme, risk entrepreneurs advocate more intensive management or face the consequences in court. Whether you are a homeowner with a few trees in your garden, or a corporate manager looking after whole populations, where does the balance lie?
Doing nothing is rarely an option unless the trees are so remote from access that there is no realistic chance of harm, so the default expectation from the courts is that proactive management is usually necessary. Similarly, in a corporate environment, although costs may be reduced by relying on informal reporting of tree hazards by employees and the public, it is unlikely to be defensible in court unless supplementing an existing formal regime of inspections by trained professionals.
Proportionality and balance also matter. There is no automatic need for expensive detailed investigations unless there are obvious problems, with a quick visual check being the starting point.
Another common misconception is a need for a detailed inventory of all your trees. This approach, although commonly applied, is disproportionate and unnecessary to refute liability. Although all trees in occupied areas must be checked, only those needing work must be recorded, which offers huge cost savings over recording data on every tree.
The courts also recognise a difference between homeowners with a few garden trees and corporate managers who have responsibility for whole populations. It is acceptable for homeowners to check their own trees if they can identify obvious hazards, and experts are only needed if they discover a problem. In contrast, there is a clear expectation that corporate duty holders should use trained professionals as the mainstay of a formal tree-inspection regime.
All this is unlikely to change, but there is a big shake-up to inspection frequency on the horizon. Ash dieback is killing trees across the country and it is notoriously unstable once decay sets in. Experience shows that infected trees can rapidly deteriorate and become dangerous over a short period. Historically, an inspection frequency of every three-to-five years worked for most species, but dying ash is different.
Change is coming, and the time for risk managers to review and adjust their policies is now.
Jeremy Barrell is managing director of Barrell Tree Consultancy