Practical techniques: Trees
UK and Ireland
Trees can have great wildlife, landscape and amenity value and, as such, should be considered carefully during planning and development. Trees may support a variety of other species, some rare, including insects, fungi and epiphytes, and provide important roosting and nesting sites for birds.
Protection and its implications
The Town and Country Planning Act 1990 (as amended), the Planning (Northern Ireland) Order 1991 and the Planning and Development Act 2000 (Ireland) places a duty on local planning authorities to ensure that they make adequate provision for the preservation and planting of trees when granting planning permission. Government policies dictate that special consideration should be given to veteran trees (a tree that is of interest biologically, culturally or aesthetically because of its age, size or condition), and that planning authorities encourage the conservation of these trees as part of development proposals. Consequently, most local planning authorities have a policy on tree preservation in their local planning documents. The applicant should therefore expect planning conditions which require the protection of existing trees and/or the planting of new trees as part of the development.
Individual trees, groups of trees and woodland may also be protected in the interest of amenity via Tree Preservation Orders issued by the local planning authority under the Town and Country Planning Act and the Town and Country Planning (Tree Preservation (England) 2012) Regulations 1999, the Town and Country Planning (Tree Preservation Order and Trees in Conservation Areas (Scotland)) Regulations 2010, the Planning (Trees) Regulations (Northern Ireland) 2015 or the Planning and Development Act 2000 (Ireland). Government policy is that local authorities should consider the nature conservation value of trees when determining amenity interest. Tree Preservation Orders prevent the cutting, uprooting, damage and destruction of trees covered by the order unless the local authority has given prior consent. Similar protection applies to mature trees within a designated conservation area. However, there are certain exemptions including carrying out development permitted under Town and Country Planning (General Permitted Development) Order 1995 (Amendment 2012) or when planning permission has been obtained under the Town and Country Planning Act. Planning permission may not be granted for developments that affect trees with a preservation order unless the local authority is convinced that the need for the development outweighs the amenity value of the trees. In this case, there would usually be a requirement to plant trees to compensate for the loss either on or near the site.
Mitigation techniques
Consideration should be given to keeping any mature trees within the site; these will not only retain some features of benefit to wildlife but also improve the surroundings for the user of the new development. Trees that are retained should be protected carefully during the development process. Damage can occur all too easily from root severance during excavations and soil compaction by vehicles or material. In the UK, operations should be restricted around trees to be retained in accordance with the British Standard BS 5837:2012 Trees in relation to design, demolition and construction – Recommendations.
When planting new trees, either to compensate for those lost or for enhancement, consideration should be given to planting native species of local provenance (although this may not always be necessary in urban environments). Newly planted trees are likely to require a period of aftercare and maintenance until they become established.
Timing of works
When carrying out works around trees, erecting protective fencing at a minimum distance from the tree is important (see British Standard BS 5837:2012 Trees in Relation to Design, Demolition and Construction – Recommendations). If this is done correctly it should avoid damage to the roots and other parts of the tree so the timing of the works is not a factor.
It is desirable to avoid pruning operations when deciduous trees are coming into leaf, and in autumn when they are losing their foliage.
The best time to plant new trees is between November and February, but avoiding periods of frosty weather or cold winds.
However, it is better to plant deciduous trees before the end of December as they are then less likely to suffer if the following Spring is dry. Coniferous trees are best planted in autumn or spring as this is when their roots are most active.
Further reading
British Standard BS 5837:2012 Trees in Relation to Design, Demolition and Construction.
Tree Council of Ireland (2010) Amenity Trees and Woodlands, A Guide to their Management in Ireland, Tree Council of Ireland, Dublin.
Natural England (2015) Ancient woodland and veteran trees: protecting them from development. https://www.gov.uk/guidance/ancient-woodland-and-veteran-trees-protection-surveys-licences