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 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.
   

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.

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.

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.
 

• Copies of the British Standard - click here.
   
• Veteran Trees – a guide to good practice - click here.
   

• See also:
  Mynors, C. (2002) The Law of Trees, Forests and Hedgerows
    

• The English planning system
   
• The Scottish planning system
   
• The Welsh planning system
  (Y Drefn Gynllunio yng Nghymru)
   
• The planning system in Northern Ireland
   
• Planning permission
   
• Permitted development in Britain
   
• Planning appeals and public inquiries
   
• Minerals applications
   
• The local government ombudsmen