Tree surveys and hedgerow survey
Used to assess the merits of existing trees as part of any development scheme, including tree canopies of adjacent sites which overhang the application site boundary.
Where there are trees or hedgerows on the site or within 15 metres of the boundary of the site. The reason for this is that The British Standard 5837, the Root Protection Area (RPA) is calculated by multiplying the diameter of the tree at breast height in metres by 12, but is capped as an area with a radius of 15 metres. Development that is within 15 metres of a tree has the potential to damage its roots.
A tree survey may be needed for the following applications:
- Householder Planning Applications
- Full Planning Applications
- Outline Planning Applications
- Approval of Reserved Matters Applications
- Removal or Variation of Conditions (Minor material amendments, also know as S.73 Applications)
Please remember, it is much easier to think about existing trees at an early stage when planning a project.
A tree survey must be submitted where there are trees within a proposed planning application site, or on land adjacent to an application site that could influence or be affected by the development.
Information will be required on which trees are to be removed and retained and the means of protecting those to be retained during construction works.
This information should be prepared by a qualified arboriculturist in accordance with British Standard 5837: 2012 (or any subsequent updates) Trees in relation to design, demolition and construction recommendations.
Contents of a tree survey
The survey must include:
- A topographical survey plan showing the exact locations of the tree(s)
- A schedule to the survey including the following:
- a reference number for each tree or group to be recorded on the tree survey plan
- species listed by common name
- the approximate height
- the stem diameter measured in accordance with Annex C of BS 5837:2012 (or any subsequent updates)
- the branch spread at four cardinal points
- existing height above ground level of the first significant branch and canopy
- life stage (e.g. young, semi-mature, early mature, mature, over-mature)
- general observations, particularly of structural and/or physiological condition
- the removal/retention category U or A to C grading (see 4.5 and table 1 and 2 of BS 5837:2012, or any subsequent updates)
- an estimate of remaining contribution in years (less than 10, 10 or more, 20 or more, 40 or more)
- the preliminary management recommendations
In some cases, a full tree survey may not be necessary. It may be sufficient to submit a Tree Constraints Plan.
Contents of a Tree Constraints Plan
The Tree Constraints Plan should be a combination of the information gathered during a topographical survey (location of all trees, shrubs and hedges and other relevant features such as streams, buildings and spot level heights) and an accurate tree survey.
It is important to remember that the parts of a tree that lie below the soil surface, its roots, are just as important as those above ground (trunk, branches, leaves). Every effort should be made to ensure that the roots of retained trees are not damaged during the construction process. Root problems can lead to a decline in a tree's health resulting in the need for a tree to be removed or even structural collapse. Tree roots can be easily damaged by:
- crushing by vehicles/plant equipment and/or storage of building materials or soil
- compaction of the surrounding soil leading to root death by asphyxiation (lack of oxygen) or drought (inability to obtain water)
- severing and removal of roots by excavation
- poisoning from, for example, spillage or storage of fuel, oil or chemicals
- changes in soil levels around trees resulting in root death as a result of exposure or asphyxiation
- installation of impermeable surfaces leading to a decline in tree health due to lack of water
It is vital therefore that the Tree Constraints Plan should also clearly show the Root Protection Area of each tree.
The Root Protection Area can be equated to a circle, using the tree as the centre-point, with a radius that is 12 x the tree's diameter at breast height for a single stemmed tree, or alternatively 10 x its basal diameter measured above the root flare for a multi-stemmed tree.
A Tree Protection Plan
Trees are particularly vulnerable on development sites and may be affected either immediately if removal or pruning is necessary to accommodate a development, or in the longer term.
This may be as a result of disturbance during the development process or following pressure to remove or prune trees from the occupants of new buildings.
The design layout should take these issues into account.
Once it has been decided which trees, hedges or shrubbery are to be incorporated into a design layout it is important to ensure that they will survive the development process.
A Tree Protection Plan is an essential aspect of tree protection with regard to development.
The Tree Protection Plan is a scale plan showing:
- any proposed or existing buildings or structures
- all retained trees both on and neighbouring the site and their corresponding Root Protection Areas and crown spreads (North, East, South and West)
- the location of protective fences or barriers (details of how these are to be constructed must also be supplied)
- proposed location of all plant and materials storage
- drainage runs, roads and driveways
- existing and new accesses
- any other surface or underground features that may affect the trees on or neighbouring the site
An Arboricultural Method Statement
British Standard 5837: 2012 (or subsequent updates) Trees in relation to design, demolition and construction, recommendations
If construction or the laying of hard surfaces is allowed within the Root Protection Area (RPA) of a tree, or if any part of the development process is likely to detrimentally affect any retained trees, then it is likely that an arboricultural method statement will be required.
The statement should explain the methodology for the implementation and mitigation of any aspect of development, where there is potential for the loss of or damage to a tree(s).