All work is carried out according to the British Standard 3998 – 2010 Tree work – Recommendations:
- involves the removal of a proportion of secondary and small, live branch growth from throughout the crown to produce an even density of foliage around a well spaced and balanced branch structure, it should usually be confined to broadleaf species. Crossing, weak, duplicated, dead and damaged branches should be removed.
- involves the removal of the lower branches to a given height above ground level, it is achieved either by the removal of whole branches, or by the removal of only those parts which extend below the desired clear height.
- should aim to produce a tree which in maturity will be free from major physical weaknesses. Unwanted secondary leading shoots and potentially weak forks which could fail in adverse weather conditions, e.g. strong wind or snow, should be removed.
- dead, dying or diseased wood, stumps of broken branches, unwanted epicormic shoots, climbing plants, e.g. ivy, and rubbish accumulated in branch forks should be removed. Other objects such as wires, clamps or boards should also be removed when this can be done without inflicting undue damage on the tree concerned.
- some trees can be reduced in height and / or spread while preserving a natural tree shape by crown reduction.
Crown reduction should be carried out by cutting back to a side bud or branch to retain a flowing branch line without leaving stumps. All cuts should be made just outside the line of the branch bark ridge and branch collar of the retained branch.
Very substantial crown reductions should, ideally, not be made during a single growing season since severe loss of leaf area and multiple wounding may impair a tree’s defences against diseases and decay.
- pollarding in some circumstances has been a traditional form of management, it should not be used on trees that have not previously been pollarded, as the large wounds created initiate serious decay in mature and maturing trees.
Very heavy pruning may kill some species (e.g. beech) while others will be stimulated to produce a proliferation of very dense regrowth of shoots from around each wound. Such shoots grow vigorously and have weak attachments to the tree making trees potentially dangerous unless recutting is done frequently. This risk is smaller for very young trees, but it is better to plant an appropriate species for the site rather than to restrict the size of an unsuitably wide spreading or tall growing species.
- trees in confined spaces, or near to other trees or shrubs which are to be retained, need to be carefully taken down in sections with the use of ropes and rigging devices.
Some trees may warrant the use of a crane or a mobile elevated work platform for increased safety.