Keeping trees safe and well; what’s expected of owners and managers?

Oak tree in the landscape at Bodnant garden

A mature oak tree frames a vista on the lawn at Bodnant Garden, North Wales

What makes a tree safe?

When it comes to working on trees it is often a highly emotive subject, especially when they are in very public places, and have powerful connections to community. When a tree fails it can have devastating effect, and yet it is common to see sadly unnecessary interventions to healthy trees, simply on the grounds of ‘safety’.

Professional tree inspectors never assess a tree as safe, they will weigh up many factors to judge likelihood of failure. As a complex natural organism, there are external signs that an inspector can use to determine tree health, from a simple bulge in the trunk to a fruiting fungal body within the tree. A rounded bulge to one side can indicate internal decay, or a vertical rib can mean that a long internal crack is present, each of which can alter the structural capabilities. There are aggressive fungi and passive ones, each having  unique decay outcomes, telling us much more about the complex event.

Ganoderma fungal infection on a mature beech tree affects its safety.

A veteran beech displaying multiple Ganoderma sp. brackets, indicating significant decay, at Leeds Castle, Kent

What is expected of tree owners and managers?

The law is very clear, and states that you have a ‘duty of care’ to prevent foreseeable injury or harm to visitors to your land, which extends to unlawful trespassers (Occupiers’ Liability Act 1957 and 1984). This is the same for the domestic homeowner with one tree, as it is for large estates and local authorities. Taking ‘reasonable care’ under this duty, in reality means that trees must be routinely inspected by a suitable individual, based upon the risk likelihood.

Tree inspection needn’t be seen as an onerous layer of bureaucracy, wrapped up in health and safety law, in fact it is far from that. Keeping a check on the health and vitality of special plants, pets and ourselves is important, and it’s the same for trees. A regular check can spot an issue early on, and often result in simple task rather than a disaster – important for special trees. At Land and Heritage we are undertaking such work at Leeds Castle in Kent, Plas Glynllifon in North Wales, and for Lostwithiel Town Council in Cornwall.

Trees and woodlands are an important part of the historic landscape.

Tree collections within historic landscapes need careful management, especially when open to the public, as in the pleasure grounds and parkland at Leeds Castle

Who is best to inspect trees?

There are a lot of folk who will have an opinion, but knowledge and understanding is important, especially with ongoing new research. It is common for tree surgeons to give poor advice, and many tree owners think work needs doing when it doesn’t. An independent arboricultural consultant is always the best starting point, having the highest level of training and experience, and can often save future expenditure following an inspection (find out more here). There are a number of simple courses available too, which offer entry level skills for assessing trees regardless of your background (here are some examples)

Matt Jackson