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Benbow Brothers Timber Ltd

Technical Glossary

Technical Glossary

some information on various technical aspects of tree surgery.


The cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants. The science of arboriculture is a field of botany that studies how these plants grow and respond to human practices and to their environment.


Someone trained in the practice of Arboriculture.


Strengthening or supporting the tree by means of cables, rods, webbing or similar materials

Branch bark collar

A swelling of the branch at the base where it joins the trunk. More noticeable in some species than others. The collar should never be cut.

Branch bark ridge

A line of rough bark where the upper side of the branch joins the trunk. More noticeable in some species than others. The ridge should never be cut.


Scar tissue in bark, laid down by the tree to cover a wound, such as a pruning cut.

Cavity Work

Removal of material from cavities and drilling to apply to drainage to the cavity. Whilst previously this was common practice, it is now considered ill advised, as it may accelerate damage to the tree.

Co-dominant Stems

When two or more shoots of equal size and vigour compete for dominance.

Conservation Area

Designation of the Local Planning Authority (LPA) for an area that legislates that the LPA must be notified at least six weeks before any work is done. Failure to notify the LPA is a criminal offence.


Cutting down a tree to within three hundred millimetres (12″) of the ground at regular intervals (on a one to five year rotation). Traditionally this is used on species like Hazel and Sweet Chestnut to provide stakes. Coppicing was extensively used through the region for creating firewood until the mid-twentieth century, and is seeing a resurgence in some rural areas.


The area of the tree formed by the branches and canopy above the stem (the trunk up to the first branch).

Crown Clean

The removal of dead, diseased, weak, broken and crowded branches from the crown of the tree. Parasitical climbing plants such as ivy are also removed to improve the health of the tree.

Crown Lifting/Raising

Cutting the lower branches of the tree away to increase the distance between the ground and canopy. Usually reserved for younger trees to avoid scarring.

Crown Reduction
Arborist conducting a crown reduction in climbing harness
A little off the top

The selective removal of outer branches to reduce the overall size of the canopy and alter the shape of the crown. This may be required to reduce the wind resistance on the tree, or the water uptake, to allow more light through the tree or due to danger posed to buildings or people.

Crown Thinning

The selective removal of branches throughout the canopy to reduce the size of the canopy but preserve the shape of the tree. Crown thinning is usually only used on deciduous broadleaf trees. Crown thinning opens the foliage of the tree, reduces weight on the branches and allows more light through the tree.

Dead, Dying, Dangerous or a Nuisance

The phrase used to describe trees that legally exempt themselves from Tree Preservation Orders and Conservation Areas protection. Whilst it may be apparent that a tree exempts itself in this way it is always advisable to have a trained professional advice.


When a tree exhibits signs of stress, lack of vigour or is dying. This may be due to disease, infection, or environmental factors.


Decline that proceeds from the tips of branches in toward the trunk slowly.


The inactive condition of deciduous trees during the winter. Characterised by lack of leaves, and little or no growth.

Drop Crotching

Shortening branches by pruning off the end back to a side branch which is at least one-third the width of the removed branch.


Application of a substance (such as Nitrates or Manure) to the trees rooting area (and occasionally the tree itself) to promote growth, or reverse decline or dieback.

Flush Cut

The removal of a branch by cutting through the branch collar or ridge, thereby reducing the ability of the tree to callus.

Forked Growth

see Co-dominant Stems

Formative Pruning

Pruning the tree whilst it is young to correct weakness, or establish a particular shape.

Fruiting Bodies

The spore-bearing body of a fungus. See our pages on Fungi for details.


An older term for the pruning of side branches, previously this was accomplished with a single vertical cut. Three special cuts are used to reduce the stress to the rest of the tree in modern tree surgery.


A tree feller. A worker skilled in felling trees.


Covering pruning cuts or wounds with a paint or tar substance, believed to reduce the chances of infection to the tree. In actual fact research has demonstrated that the seal reduces the ability of the tree to heal itself.


Disease inducing (usually referring to Fungi)

Maiden Tree

A tree that has not been cut or “pollarded”.


Used in three different contexts and often misunderstood.

  1. Traditionally the removal of all the branches from the trunk of the tree. Mature trees do not heal well from such treatment and may die.
  2. Regular (annual or biannual) pruning of branches back to the same point, forming a pollard head. This is usually done above head height (2-3 metres from the ground) to encourage fresh growth from the pollard head.
  3. A tree that has been Pollarded (usually in the second sense). As opposed to a maiden tree

The cutting and removal of a limb whether it be a side branch from a main branch or main branch from the trunk of the tree. All cuts wound the tree, so care must be taken with cuts at the correct place and angle to reduce the damage and help the tree to heal.

It is also advisable when possible to avoid pruning when the tree is growing leaves or needles (spring) and when the tree is losing leaves or needles (autumn).

Prunus species (Cherry, Prunes, etc) should be pruned immediately after flowering, as they are most resilient to infection at this time.
Maple, Birch, Beech, Walnut should be pruned when in leaf or immediately after leaf-fall.
Magnolia should be pruned in high summer to avoid unsightly “bleeding”.
As a rule of thumb, if it flowers before June 1st, prune it after flowering.
If it flowers after June 1st, prune it before flower buds are visible.

Large limbs should be cut in a specific way.

First a cut is placed under a branch, then out and above, and then a third cut removes the end
As simple as 1-2-3
  1. A first cut is made some way out on the limb under the limb. This protects the tree from bark tearing when the limb falls.
  2. A second cut is made several inches outside of this, this allows the limb to droop under the weight of the branch and should cause the branch to snap free
  3. Finally a cut is made at the base of the limb outside of the branch collar, to remove the stump.
Root Pruning

The Pruning back of roots (in a similar manner to the pruning of branches). Root pruning will almost always disturb the balance of the tree, affecting its stability. Always seek professional advice before cutting roots.


Another term for Painting.


The practice of managing the establishment, growth, composition, health, and quality of forests and woodland. The name comes from the Latin silvi- (forest) + culture (as in growing)


An older term for the removal of the head or crown of the tree by making horizontal cuts.

Tree Preservation Order

Statutory protection applied to a tree or trees. Work on trees with a TPO cannot be treated or felled without prior written consent from the LPA. Failure to gain consent may constitute a criminal offence.

Tree Surgeon

Someone trained in the arboricultral practices of tree maintence and tree care.

If you require more information on one of these topics please contact us.