Tree Surgery Terminology
Below is listed a collection of the words and phrases you are likely to encounter whilst looking into tree surgery and arboriculture.
Amenity Value
The environmental and landscape benefits of trees as opposed to their commercial value for timber.
Arboriculture
Management of individual trees or groups of trees primarily for their amenity value.
Crown
The section of the tree formed by its branches and usually starting above its stem.
Crown Thin
Crown thinning is the removal of a small portion of secondary and small live branches to produce a uniform density of foliage around an evenly spaced branch structure. It is usually confined to broad-leaves species. Crown thinning includes crown cleaning and does not alter the overall size or shape of the tree. Common reasons for crown thinning are to allow more light to pass through the tree, reduce wind resistance or to lessen the weight of heavy branches.
Crown Lift (or Crown Raise)
Crown lifting is the removal of the lowest branches and preparing of lower branches for future removal. Good practice dictates crown lifting should not normally include the removal of large branches growing directly from the trunk as this causes large wounds which may jeopardise the long term future of the tree. Common reasons for crown lifting are to bring more light and give access for traffic. In the UK common practice dictates clearance for vehicles is 5.2 metres (17 feet), and for pedestrians 2.5 m (8 feet)
Crown Reduction (or Branch Reduction)
Crown reduction is used to reduce the height and/or spread of the crown of a tree by the removal of the ends of branches whilst maintaining the tree's natural shape as far as practicable.
Crown Clean (or Deadwooding)
The removal or dead, dying, diseased, broken, crowded, weakly attached and low-vigour branches as well as climbing plants (e.g ivy).
Bracing
Bracing is a term used to describe the strengthening or supporting of a tree by means of cables, rods, webbing or similar.
Branch bark ridge and collar
More noticeable on some species than others are branch bark ridges, which is protruding bark at the top of a junction (crotch) of two branches; and continues downward from crotch. Also more noticeable on some species than others is the branch collar; a swelling at the base of the branch. Neither the branch bark ridge nor collar should be cut.
Callus
Scar tissue laid down by the tree in order to cover and protect a wound, eg a pruning wound.
Cavity work
Removal of material from cavities and drainage of cavities achieved by drilling through living wood. Modern research indicates this should not normally be carried out.
Conservation Area
Conservation Areas are 'areas of special architectural or historic interest the character and appearance of which it is desirable to preserve and enhance' (Civic Amenities Act 1967). They are areas of land awarded protected status by local planning authorities based upon against local and regional criteria.
They are designated usually for the preservation of buildings but they are also designated because of local and regional history, architecture, open spaces, such as gardens, parks and greens and trees.
With some exceptions, trees are protected in conservation areas and are treated in a similar manner to those covered by a Tree Preservation Order. Any work to trees within a conservation area regardless of the health or physical state of the tree, must be consented by the local Council prior to any work being undertaken, this process can take up to six weeks. It is considered an offence to carry out the work within that period without the consent of the relevant Council. Applications for works in conservation areas can be awkward and time consuming, and it is recommended that you get a professional arborist to apply for your consent on your behalf, as an arboricultural report is now deemed as a necessary part of an application. We will undertake applications for our clients free of charge.
Coppicing
The cutting down of a tree within 300 mm (12 in) of the ground at regular intervals (typically on a one to five year rotation). Traditionally applied to certain species such as Ash, Hazel and Sweet Chestnut to provide stakes, poles, firewood etc.
Dead, Dying Dangerous or a Nuisance
The catch-all phrase describing the conditions of trees to which protection afforded by Tree Preservation Orders or Conservation Areas does not apply. Legal definitions are the subject of much debate, sometimes through the courts, tree inspections by Colin White Tree Surgeons can give advice on such matters.
Decline
When a tree exhibits signs of a lack of vigour and progressing towards its death.
Dieback
Tips of branches exhibit no signs of life. As decline progresses so more branches are affected and to a greater extent.
Dormant
The inactive condition of a tree, usually during the coldest months of the year when there is little or no growth and leaves of deciduous trees have been shed.
Drop Crotching
Shortening branches by pruning off the end back to a lateral branch which is at least 1/3 diameter of the removed branch.
Fertilising
The application of a substance usually to the tree's rooting area (and occasionally to the tree) to promote tree growth or reverse or reduce decline.
Flush Cut
A bad practice of removing a branch by cutting very close to the branch to be retained, cutting through the branch bark ridge and/or collar, thereby reducing the ability of the tree to callus.
Forked growth (Co-dominant stems)
The development of two or more leading shoots of roughly equal size and vigour competing with each other for dominance.
Formative pruning
Pruning during the early years of a tree's growth to establish the desired form and/or correct defects or weaknesses.
Fungi/Fruiting bodies
Any spore-bearing structure on a stalk (like a toadstool) or attached directly to the tree (a 'bracket' fungus). Note: some are harmful (cause disease - pathogenic), some are harmless (living on material already dead - saprophytic) and some are beneficial (symbiotic).
Hanger
Dead branch fallen from the crown but caught by, and resting on, branches lower down.
Lopping and Topping
Generally regarded as outdated terminology but still part of Planning legislation. Lopping refers to the removal of large side branches (the making of vertical cuts) and topping refers to the removal of the head or crown of the tree (the making of horizontal cuts). Often used to describe crude, heavy-handed or inappropriate pruning.
Mature
Trees that have attained full size.
Painting or Sealing
A now uncommon and discredited practice of covering pruning cuts or other wounds with a bitumen-type substance. Research has demonstrated that this is not beneficial and may in fact be harmful to trees.
Pathogenic
Disease inducing - usually referring to fungal fruiting bodies.
Pollard
Traditionally and still commonly used this term describes the removal of all branches from the trunk. Mature trees that have not been pollarded before are generally not suitable candidates for pollarding due to the large wounds that such treatment produces which may jeopardise the long term future of the tree. A less frequently used definition can mean the regular (annual or biannual) pruning back of small branches to the same point resulting in the formation of a 'pollard head'. Pollarded trees usually require regular treatment of re-growth. Pollarded trees are a common sight on French boulevards.
Root Protection Area (RPA)
The RPA of a tree is the area around its base that contains sufficient rooting volume to ensure the survival of the tree in the event of nearby soil disturbance (as on a development site). The RPA is calculated using guidelines in BS 5837 (2005) Trees in relation to construction - Recommendations
Root pruning
The pruning back of root (similar to the pruning back of branches). This has the ability to affect tree stability so it is advisable to seek professional advice prior to attempting root pruning.
Senescence
The third phase of a tree's life, after youth and maturity, when the leaf area of the crown tends to diminish. Veteran trees are generally senescent.
Tree Preservation Order (TPO)
A Tree Preservation Order is an Order made by a Council in respect of a tree(s) because the tree is considered to bring amenity value to the surrounding area. The order makes it an offence to cut down, uproot, prune, lop or damage the tree in question without first obtaining the Council’s consent. A TPO can apply to a single tree, a group of trees or a woodland.
The Council must give notice of the making of a TPO and will consider any objections to it before making the decision whether to confirm it, to confirm it subject to modifications or to not confirm it.
Anyone who wishes to fell or carry out work to a tree protected by a TPO must apply to the Council to obtain permission. That person does not have to be the tree owner but they must state the reasons for making the application, the works required and make it clear to which tree the application relates. Colin White Tree Surgeons will undertake the application of any TPO or Conservation covered trees free of charge for our customers.