What constitutes a dangerous or hazardous tree

A dangerous tree is one which is in such a poor condition that it may be about to collapse either in part or whole. A dangerous tree may or may not be hazardous depending upon where it grows. A tree in a privately owned field is less potentially hazardous than one in a public park, for example.

How a dangerous tree differs from a defective tree

Most trees have defects, but the vast majority do not render a tree dangerous. Defects may include minor dead wood where squirrels have stripped bark or minor decay pockets where bark has been damaged and the tree has suffered bacterial or fungal infection. It is the type and extent of the defect that is important in determining whether or not a tree is dangerous.

The symptoms which can make a tree potentially dangerous or hazardous

There are a number of defects which, depending upon their extent, may be regarded as potentially hazardous.

• See Living with trees: A guide for householders

Tall trees

Tall trees are not necessarily dangerous. A tree will grow (within its species limits) as large as the space, light, water, nutrition and oxygen available to it permits. Trees cannot grow too tall - except in human perception.

Leaning trees

Leaning trees are not necessarily dangerous. One of the reasons a tree grows with a lean is because it is in close competition with another specimen and has been forced to grow at an angle to chase the light. In response the tree lays down denser wood on one side of its trunk. There may be a problem however if a previously vertical tree suddenly develops a lean.

Hollow trees

Certainly some hollow trees may have so little healthy tissue surrounding the hollow area that they must be regarded as dangerous, but this is by no means the norm. Trees do not become hollow overnight - it can take decades - and while the centre of the tree (the heartwood) may be decaying, the tree continues to lay down healthy wood (sapwood) around the outside of its trunk. This results in the formation of a cylinder, the strength of which depends upon the percentage of healthy to unhealthy tissue.

Permission to cut down a dangerous tree

You do not require consent to cut down a tree that is an imminent danger or remove branches to make it safe. However, you should provide the council with a 5 day notice of your intention to remove the tree, together with photographic evidence. This will then be put on file and you will be sent confirmation with regard to whether there is sufficient justification to remove the tree or branches under this exemption.

If the tree requires emergency removal you can do this but you should try and contact us first and you should make sure that you, or the person carrying out the work, collects all the necessary evidence to prove the tree was dangerous - photos, branches, arboricultural report, fungal samples and other evidence.

The burden of proof lies with the tree owner and person carrying out the work to prove the tree was dangerous. If a tree is removed without sufficient evidence this could lead to prosecution. If in any doubt please contact the Trees Section.

If a tree is removed because it is dangerous the law requires that a replacement tree is planted.

• Making a tree work application

Trees contacts

Tree Preservation Orders (TPOs), trees in conservation areas and tree work applications

Report trees causing an obstruction on pavements and footpaths, or obscuring street lighting

• Report Overhanging vegetation and/or weeds

Find out who owns trees

• Land ownership

Trees owned by the council