Trees, roots and the duty of care

Look down on almost any sizeable site and the trees read as the soft part of the picture, the green relief between the hard edges of buildings, car parks and roads. From the ground, and from a manager's desk, they are rather more complicated. A mature tree is an asset that took decades to grow and cannot be replaced on any useful timescale. It is also, simultaneously, a liability with roots that move, limbs that fall and a root system that interacts with foundations and drains in ways you cannot see. Frankfurt's dense green belt and the wooded edges of its commercial districts make the point neatly: the trees are part of what makes the place liveable, and they are also part of what the people responsible for the land have to manage.

That double character, asset and hazard at once, is what makes trees a genuine duty rather than a gardening footnote. A manager who treats them only as scenery is carrying a risk they have not assessed.

Two failure modes, both slow

Trees cause problems in two main ways, and both tend to develop slowly enough to be missed until they are not.

The first is structural failure of the tree itself: a limb that drops, or in the worst case a trunk that fails, onto people, vehicles or buildings below. This is the acute hazard, and it is the one with the clearest duty of care, because a falling tree on an occupied site is a foreseeable harm. The risk concentrates wherever people gather beneath canopy, car parks, footpaths, play areas, building entrances, which is precisely where trees are most valued and most watched but least often formally assessed.

The second failure mode is subsidence. Tree roots draw moisture from the soil, and on clay soils that shrink as they dry, a large tree near a building can contribute to ground movement that damages foundations. This one develops over seasons and years, shows up as cracking that is easy to attribute to other causes, and ties the tree directly to the building it sits beside. Removing the tree is not always the answer either, because on the same soils the ground can heave as it rehydrates. The interaction between tree, soil and structure is genuinely technical, and it rewards expert assessment rather than instinct.

The asset that the law sometimes protects

Trees are also the one site feature that may carry its own legal protection, which removes the manager's freedom to simply deal with them. A tree subject to a tree preservation order, a TPO, generally cannot be cut down, topped, lopped or otherwise worked on without consent from the local planning authority, and trees within a conservation area carry similar constraints. The protection exists for good reasons, but it changes the management problem: the manager who spots a hazardous limb on a protected tree cannot just send someone up a ladder. They have to work within a consent process, which takes time, which means the hazard has to be identified early enough for that process to run.

This is where knowing your trees as a recorded inventory, rather than a vague green presence, starts to matter. A protected tree you have logged, with its status known, is one you can manage within the rules. A protected tree you only discover is protected when you try to deal with it is a problem.

What a sensible regime looks like

The duty of care over trees does not demand heroics. It demands a regime proportionate to the site, much like every other site hazard. A workable approach has a few recognisable parts:

• Know what you have. An inventory of significant trees, their location and their protection status, is the foundation everything else hangs off.
• Inspect on a cadence proportionate to risk, with closer attention to trees overhanging places people gather or sit near buildings.
• Escalate to an arboricultural specialist where a tree shows signs of decline, disease or structural weakness, because diagnosis here is genuinely expert work.
• Record inspections and the actions arising, so the history of a tree is visible and a duty of care can be evidenced.
• Track protected trees explicitly, so their status is known before any work is contemplated rather than discovered after.

None of this is exotic. It is the same logic that governs every other thing on a site that can hurt someone or damage a building: know it is there, watch it on a sensible rhythm, and keep a record that proves you did.

Trees belong on the site record, not beside it

The recurring mistake is to treat trees as grounds-maintenance, separate from the compliance picture of the site. They are not. A tree near a building is a structural consideration. A tree over a footpath is a safety consideration. A protected tree is a planning consideration. Each of those belongs in the same record as the drains, the boundaries and the buried services, because they are all features of the land that someone is responsible for proving they manage. We have written about managing the land a building sits on and about tree preservation orders and the survey behind them; both come back to the same idea, that the site is not an afterthought to the building but a managed thing in its own right.

Holding trees on the site record, with their inspections and protection status against them, turns a vague green liability into a tracked one. The manager can see which trees are due an inspection, which carry a TPO, and what action is outstanding, in the same place they manage everything else about the land.

A short, practical close

Trees ask for the same discipline as any other site hazard, complicated by two facts: they fail slowly, in ways that are easy to miss, and they may be legally protected against the very work that would make them safe. The answer is an inventory, a proportionate inspection cadence, expert escalation when something looks wrong, and a record that proves the duty of care was taken seriously. SAMRISK keeps the trees on the site record alongside the rest of the land, so they are managed rather than admired. This is general information rather than arboricultural or legal advice, and individual trees, especially protected ones, should be assessed by a competent specialist.