Common Arboricultural Terms
🌳🌳 A Beginner's Guide to Common Arboricultural Terms A Tree Lover Should Know
Whether you're a homeowner, property developer, landscape planner or a budding young arborist with an interest in tree care, understanding basic arboricultural terminology is essential. The world of tree surgery, tree maintenance, and urban forestry comes with its own language. In this guide, we break down the most common arboricultural terms you might encounter, with clear definitions to help you become tree-smart.
🌱 What Is Arboriculture?
Arboriculture is also commonly known as Tree Surgery it is the science and practice of cultivating, managing, and studying individual trees, shrubs, vines, and other perennial woody plants. It’s a specialised field akin to horticulture that focuses on the health, safety, and aesthetics of trees, especially in populated areas.
🌿 Common Arboricultural Terms (With Definitions)
Tree Surgeon (Arborist)
A tree surgeon, or certified arborist, is a professionally trained tree care expert with the ability to care and maintain trees. Arborist Services should carry out work to BS3998 or better and may include services like planting, pruning, tree removal, root aeration and pest control. It is important to verify they have the correct training and certification and experience before they carry out work on your trees. Why? Untrained tree workers can cause long term damage to trees, and their work probably won't be covered by insurance.
Crown Reduction
A Crown reduction involves reducing the overall size of a tree’s canopy. This technique helps in managing tree size, preventing interference with structures, and improving light and wind penetration. In the main trees would far rather we leave them alone so this work is mostly due to urban requirements where the tree is starting to outgrow its environment. Crown reduction, along with any tree pruning should be carried out by a qualified tree surgeon who understands how to reduce and thin a tree canopy correctly. Poor or heavy pruning practice not only leaves the tree looking awful but can also cause the tree to rapidly regrow, negating exactly what you were trying to achieve with the work.
Crown Lift
A good arborist may suggest a crown lift to help reduce a trees canopy. By removing small lower branches that often extend furthest, it may be possible to reduce the appearance eof the trees size. This can be a great and cost effective way to reduce a trees impact whilst retaining it’s aesthetics. Never remove larger structural branches as this can lead to decay in the main stem.
Lopping and Topping
These terms have no place in modern Arboricultural practice. They are historical terms from the forestry industry where side branches of a tree would be lopped off and the top removed (Topping) before the tree was felled. This reduced the potential for damage to the precious timber during the felling process. They are not good Arboricultural practice.
Heavy pruning lopping and topping is unfortunately still rife and examples of ugly trees damaged in this way can be seen in every town. If your tree has got so bit you want this treatment why not just remove it and plant a nice new tree in it’s place one you can enjoy looking at.
Pollarding
Pollarding trees is a method of pruning where upper branches are regularly removed to control the tree size. Regular removal of foliage and branches prevents large wounds that can cause future decay and potentially tree failure. This traditional technique controls growth and encourages rapid wound healing. If used correctly and early in a trees life it can be a way to control the size of a tree. Pollard pruning methods are quite simple cutting back to the growth rings at the base of the branch. It is important to carry out this work regularly to keep the wounds created as small as possible. This method isn't suitable for all tree types. You will often see street trees managed in this way with popular pollarded trees being Limes (Tillia) or London Plane (Platanus x Hispanica).
Tree Preservation Order (TPO)
A Tree Preservation Order is a legal protection placed on trees by a local authority. It prohibits cutting down, topping, lopping, or uprooting a protected tree without permission. It doesn't stop you working on protected trees but before any work is carried out you will need to consult a professional arborist and put together a valid and supported plan of works to present to the local authority in a formal application the authority can then decide if they agree with your application and allow or deny any work submitted. Failure to adhere to TPO regulations can lead to substantial fines with each individual tree involved in any breach being taken into consideration. Applications and information relating to TPOs should be available from your local authority.
Root Zone / Root Protection Area (RPA)
The Root Protection Area is a defined area around a tree that must be protected from disturbance during construction or landscaping. It’s essential for tree health and longevity.
Popular belief is that tree roots are the woody bits you find in the soil, and they go down deep. Some of this is correct but if you have ever seen an uprooted tree, you will have noticed that most of the main root system is often very shallow. The main root system usually goes out as far as the trees drip line (as far as the branches); however, attached to these are tiny Mycorrhizal roots. These tiny hair like roots are generally very shallow found just below the soil surface and help draw gasses, nutrients and water in for the tree. Mycorrizal roots can stretch out much farther than the woody root system yet damage to them can be catastrophic to the trees health. Even persistent foot fall on the soil can create compaction and damage to these tree support systems.
The 2012 BS 5837 “Trees in relation to design, demolition and construction” includes recommendation’s on minimal RPA’s however I feel it fails to recognise the importance of the root system, with the designated construction zones suggested being in my opinion far too small to sustain the long term health of a tree. The damage caused by working within these zones can take several years to become visible by which time nobody but an experienced arborist will link the crown dieback and tree decline to historic root damage.
Events that can detrimentally damage a tree root system include:
- Addition or removal of soil layers
- Concrete (toxic to tree roots)
- Road Salt
- Mechanical trenching (digging)
- Excessive water
- Compaction from pedestrian, animal or vehicle access
- Chemical or fuel spillages
- Grass (A highly competitive vegetation)
- Volcano Mulching
If you are tempted to use this guide to intentionally damage a tree root system, I refer you back to the potential fines related to TPOs and legislation protecting trees within a conservation area.
Deadwooding
The process of removing dead, dying, or diseased branches from a tree. This improves safety, enhances appearance.
Where it is safe to do so modern thinking includes the potential to retain deadwood in a tree for it’s environmental benefits. Birds, bats and bugs all depend on deadwood for food and or shelter. Speak to your arborist about the environmental habitat. If removal is nessesary you may request them create an eco pile from the dead timber. A good arborist may even be able to fracture prune and bore cut a dead or dying tree to enhance it’s environmental appeal, creating a brilliant wildlife habitat.
Canopy
The canopy refers to the upper layer of a tree, formed by its branches and leaves. It plays a critical role in photosynthesis, shade provision, and wildlife habitat. See UHI (Urban Heat Island)
Tree Felling
Tree felling is the complete and safe removal of a tree, typically for safety, health, or land development purposes. It should always be done by a professional for safety and compliance with regulations.
The ability to safely remove a tree varies based on an arborists experience and certifications; just because they have a chainsaw and carry out tree work doesn’t mean they are qualified to fell every tree.
Before commissioning an arborist to carry out this work you should always request a copy of the contractors certification and insurance. As a landowner, you may be held liable if an incident occurs and you have commissioned non certified workers. This occurred on the Hodstock Forest Farm following the death of a worker in 2009 the estate Trustee was fined £10,000 + £20,327 in costs by the HSE.
Tree Planting
As arborists we are often asked what tree to plant in an urban environment. The BBC Gardeners World and even the Arboricultural Association generally recommend “small trees”. I can’t think of anything more boring than the monoculture of cherry, apple and hawthorn trees that currently blight our towns and cities. My advice, plant whatever you want from an imperial oak to a giant redwood! Am I mad? Well maybe a little but imagine the diversity this would bring to our towns.
However we do need a modicum of sense a giant redwood in a tiny terrace garden is going to impact on the foundations of surrounding properties and the shade is going to make you very unpopular with the neighbours. So the answer is simple before the tree starts to outgrow it's space remove it and plant another.
The great thing is felling and removing young trees isn’t going to break the bank. Your local arborist company will be very pleased of the work and help you select and replant a new tree. Imagine the biodiverse you could create in your neighbourhood. As young trees grow they draw in carbon helping clean our air. They look great too, no more badly pruned lollipop trees that have outgrown the urban landscape.
Urban Heat Island (UHI)
A relatively new term relating to the accumulative heat collected and stored by solid objects in our towns and cities like concrete and tarmac. Trees in towns can help reduce this issue by shading solid landscape, preventing heat absorption but also their leaf transpiration helps cool the hot air by misting out tiny droplets of water.
Bracing and Cabling
Bracing and Cabling support systems can be used to stabilise structurally weak trees. Bracing may involve rigid rods, while cabling uses flexible steel textile cables to reduce excessive branch movement and mechanical stress.
In carrying out this work you are accepting that the tree has an issue with the trees structural support system that may potentially cause some level of failure. A thorough investigation and planning should be carried out by an arborist or consultant experienced and insured in this specialist area.
Tree Survey
A tree survey is a professional assessment of trees on a property, often required before construction projects in line with BS 5837. A survey evaluates tree health, species, age, and potential risks.
Arboricultural consultants can carry out a more detailed surveys and assessments covering in more detail a trees health, levels of decay along with independent recommendations supported by industry data and professional experience. A consultant should carry professional indemnity for their advice.
In the UK as a landowner, you have a legal duty to care to ensure your trees are in safe condition.
Veteran Trees
Sadly for one reason or another, trees don’t live forever if the landscape allows they may well outlive many generations of humans, but in time size, decay and damage can bring about their decline.
Veteran trees often staghead with the tips of the branches dying back to look like antlers; this is a clear sign that the tree is under considerable stress. Large fungal brackets may appear on the stem or roots, another sure sign that something is very amiss and an arborist should be called out in investigate.
In certain circumstances, failing veteran trees can and should be where ever possible retained. Examples of veteran trees can be seen in many country parks where they are considered low risk to property or people.
Larger limbs are removed to reduce the risk of catastrophic failure using fracture pruning or coronet cuts to simulate natural branch failure and encouraging the core of the tree to decay and create habitat. The living tissue just under the bark can remain viable and hopefully the remaining stem will sprout new growth, continuing the life of the tree even in a very different form of a veteran tree or environmental monolith. Hollow veteran trees like this are known to exist, reaching many hundreds of years in age instead of just becoming firewood.
Why Understanding Arboricultural Terms Matters
Knowing arboricultural terms empowers you to:
- Communicate effectively with tree care professionals
- Make informed decisions about tree health and safety
- Navigate legal protections like TPOs
- Understand tree reports for planning and development
📈 Final Thoughts: Become Tree-Smart
Whether you're maintaining a garden or planning a development project, familiarising yourself with arboricultural terms is a smart move. Professional arborists play a vital role in urban tree management, and understanding their language can help you protect your green assets.
For expert advice, surveys, or tree services, consult a qualified arboricultural consultant or certified arborist in your area.