Background
This British Standard (BS) provides guidance on
how to decide which trees should be retained and how best to protect
them when a site is being developed. It also gives guidance on how to
incorporate trees into the new landscape.
It is aimed at planners, architects, builders,
engineers and others involved in development, as well as those
concerned with the protection and care of trees. Local authorities
have an important role in encouraging and enforcing the guidance.
Currently, the BS recommends ‘trees of particular historical,
commemorative or other value, or good specimens or rare or unusual
species’ should be retained. Ancient
trees and ancient woodland may be included in this category. The
definition allows for wildlife value to be classed as being of ‘other
value’.
However, it also recommends removal of
trees with significant fungal decay at base or main
bole and trees with a cavity or
cavities of significance for safety, which is very likely to mean
ancient trees. There is increasing awareness among arborists of the
role of hollowing and the value of decaying wood for wildlife, which
is not reflected in the BS. The Woodland Trust and Ancient Tree Forum
hope that this will be addressed in the current review of the BS.
Trees and development
Trees that are retained near a development need protecting from
construction damage. The roots are vulnerable with most of the root
system in the top 600mm of the soil extending radially for distances
frequently in excess of the height of the tree.
The factors, which most commonly affect the soil and roots are:
- compaction of the ground - passage by heavy equipment or storage
of heavy equipment on clay soils can cause significant damage
- raising soil levels, even for a few weeks
- covering the rooting area with impervious surfaces
a rise in the level of the water table
- leaks or spills of pollutants
- excess mulching with the wrong materials.
- stripping of topsoil
- excavations in the rooting area which severs roots – even
shallow excavations can cause damage.
British Standard guidance
The BS provides guidance on the minimum distance around
the tree that should be protected by fencing:
|
Minimum distances for protective fencing around trees (and
groups of trees/ woodlands)
|
|
Tree age |
Tree vigour |
Trunk diameter (at 1.5m above ground) in millimetres |
Minimum distance in metres
|
|
Mature trees |
Normal vigour |
<350 |
4.0 |
|
350 - 750 |
6.0 |
|
>750 |
8.0 |
|
Mature trees and overmature trees |
Low vigour |
<350 |
6.0 |
|
350 - 750 |
9.0 |
|
>750 |
12 |
NB: In the Veteran Trees Initiative handbook: Veteran trees – a
guide to good practice, a minimum protective distance of 15
times the diameter of the tree trunk or one metre beyond the drip line
– whichever the greater, has been identified as best practice. This
book produced by a Government agency should be recognised by
forward thinking authorities as good practice.
The BS also sets out guidance for the type of protective fencing that
should be used.
The current BS, which was published in 1991, is
currently under review and hopefully there will be changes to take
into consideration the growing awareness of the importance of ancient
woodland and ancient trees. It is anticipated that the review will be
completed in 2004.
Use of the British Standard by local authorities
This BS is used regularly by local authorities.
While it does not give specific legal protection, it does have
wide-ranging implications and tends to be backed up by the legislative
framework. The BS is often cited in local plans especially in
relation to the requirement for a BS tree survey to be submitted when
requested. A survey helps local planning authorities evaluate the
impact of any proposal on adjacent trees, and future impacts of trees
on buildings, allowing them to adjust the scheme where necessary. It
is used in most development applications where tree advice is sought. Both local planning authorities and applicants use the document and it
is commonly referred to at the appeal stage. Where planning
permission is granted, conditions may be attached which refer to the
Standard. Where these conditions are breached, enforcement action may
result which could range from serving a breach of condition notice to
getting a stop notice put on the site.
What you can do
If an ancient tree will be affected by
development it should have been properly taken into consideration in
the planning application. Check whether a tree survey to BS standards
been submitted.
Find out from the tree officer whether the local
planning authority believes that the applicant has taken sufficient
account of the tree in their application. If the grounds for removal
are based on the state of the tree, then press for arboriculturalists
with specialist experience in ancient trees to be involved to avoid
outdated attitudes and practices prevailing.
Trees that are hollow or show signs of decay need
not necessarily be felled. It may be that tree surgery would address
issues of risk while retaining a significant amount of tree.
Make sure that if an ancient tree is retained it
will be given adequate protection during the construction process.
If you are aware of an ancient tree under threat
please let us know by submitting a form through the website or telephoning us on 01476
581111.
Find out more
Related sections
Disclaimer.
This information is based on the experiences of the
Woodland Trust and Ancient Tree Forum in dealing with cases of woods
and trees under threat. While its content is intended to broaden
understanding of the process, the Woodland Trust and Ancient Tree
Forum do not accept liability for any errors or omissions or for any
loss arising from use of the information contained herein by other
parties. In any circumstances outside the knowledge and competence of
an individual, he or she should always seek advice from an appropriate
qualified professional such as a surveyor or solicitor depending on
the case. None of the information on this web-page is to be relied
upon as a statement of fact.
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