Arboricultural Impact Assessment for Planning and Development

What Is an Arboricultural Impact Assessment?

An arboricultural impact assessment (AIA) examines how a proposed development will affect the trees on and next to a site. It identifies which trees can be retained, which may be lost and what protection measures the construction project will need.

Developers usually commission an AIA early, before the layout is fixed. Finding tree constraints at this stage costs far less than redesigning a scheme after a local planning authority raises concerns.

An AIA supports many planning application submissions. Our tree consultants prepare these assessments for developers, landowners and agents across the UK.

Why Trees Matter in the Planning Process

Trees are not automatically protected, but many are. A tree preservation order (TPO) can protect individual trees, groups or whole woodlands. Trees in a conservation area are also protected, and the local planning authority must receive notice before most works begin. Both regimes sit within the Town and Country Planning Act 1990.

Even without formal protection, tree retention is a material consideration. Mature trees contribute to local character, wildlife habitat and surface water management. Unjustified tree loss, with no replacement planting proposed, can prompt objections.

An AIA gives the authority the evidence it needs to judge whether a scheme is acceptable. It also shows that the applicant has considered the trees from the outset.

The Arboricultural Impact Assessment Process

The process follows BS 5837:2012, the British Standard for trees in relation to design, demolition and construction. The standard contains recommendations rather than law, but local planning authorities widely expect applications to follow it.

• Tree survey: An arboriculturist records the species, dimensions and condition of all identified trees and places each in a quality category. Our tree surveys follow this method.
• Tree constraints plan: The survey data is used to map root protection areas and canopy spread. The plan shows where construction activity is restricted.
• Layout comparison: The proposed development is overlaid on the tree constraints plan. This highlights conflicts between the retained trees and the new buildings, access routes or services.
• Impact assessment: The consultant sets out which trees will be affected or removed. Design changes, such as moving a building line or using no-dig surfacing within root protection areas, can often reduce the impact.

The result is a clear picture of the trees a scheme can keep, and the mitigation needed where tree loss cannot be avoided.

Tree Protection Plans and Method Statements

Where trees are retained, the local planning authority may attach a condition requiring a tree protection plan and arboricultural method statement. A reserved matters approval may carry the same requirement.

The tree protection plan shows the position of protective fencing, ground protection and exclusion zones. The method statement explains how work will take place close to retained trees, including access, storage, sequencing and the installation of services.

Our tree reports bring the AIA, tree protection plans and method statement together in a form suitable for submission.

Trees, Ecology and Biodiversity Net Gain

Trees are often valuable habitat. Mature specimens may hold bat roosts, and hollow trees can support nesting barn owls. Where a development affects such features, tree work and ecological surveys need to be coordinated.

Our ecologists can carry out a bat survey or barn owl survey alongside the tree work. A Preliminary Ecological Appraisal will identify any wider constraints. Tree retention and new planting also influence the habitat baseline under Biodiversity Net Gain.

Addressing trees and ecology together avoids duplicated site visits and conflicting recommendations.

How Can Collington Winter Assist?

Collington Winter Environmental takes a pragmatic approach to development. We work with design teams to find solutions that meet planning requirements while protecting valuable trees and wildlife.

Early advice gives the best chance of a smooth planning application. Our team works across the UK from several offices.

Contact our tree consultants at info@collingtonwinter.co.uk to discuss an arboricultural impact assessment for your project.