Development Reports

Report category

Arborist Reports

An arborist report is a professional assessment of one or more trees and can document matters such as their species, condition, structure, significance and relationship to proposed works.

There are different types of arborist reports for different purposes. For a development proposal, an Arboricultural Impact Assessment (AIA) may be required to assess how proposed construction could affect trees and recommend ways to retain, protect or manage them. Other arborist reports may deal with tree condition, risk, pruning or proposed removal.

Arborist Report Specialists

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Depending on the purpose of the report, an arborist may assess trees located on the development site as well as trees on neighbouring properties or in the road reserve where the proposed works could affect them.

For development projects, the assessment can consider tree retention, proposed removal, Tree Protection Zones, Structural Root Zones, potential encroachment from buildings or excavation, and measures needed to protect retained trees during construction.

A Tree Protection Plan or specification may form part of the Arboricultural Impact Assessment or, on larger or more complex developments, may be required as a separate document.

When this may be required

An arborist report is not required for every development or every tree-related application. Requirements vary considerably between councils, sites, tree controls and types of work.

An arborist report may be required or useful where:

  • Proposed construction, excavation or earthworks could affect trees on the development site.
  • Works may affect trees located on neighbouring properties.
  • Street trees or other trees within the road reserve may be affected.
  • Development is proposed within or near the root zone or canopy of an existing tree.
  • Tree pruning or removal forms part of a development proposal.
  • A council requires an Arboricultural Impact Assessment with a development application.
  • A separate application to prune or remove a tree requires professional arboricultural evidence.
  • A Tree Protection Plan is required for trees being retained during construction.
  • Development consent conditions require ongoing arboricultural monitoring or certification during works.

City of Sydney, for example, requires an arborist report for developments that will affect trees on or near a site, including pruning or earthworks near tree roots.

City of Parramatta provides another example of why local requirements need to be checked. It states that an Arboricultural Impact Assessment and Tree Protection Plan may be requested where trees on the site, affected neighbouring trees or street trees need to be considered as part of a development application.

Not sure which reports apply to your project? See our Development Application Reports Guide.

What can an arborist report assess?

The contents depend on the type of report and the requirements of the relevant authority.

For development-related reports, an assessment may include:

  • Tree species and identification.
  • Tree dimensions and canopy spread.
  • Health and structural condition.
  • Retention value or significance.
  • Existing site conditions affecting the trees.
  • Tree Protection Zones and Structural Root Zones.
  • The extent of proposed encroachment into tree protection areas.
  • Trees proposed for retention or removal.
  • Potential impacts from excavation, buildings, paving, services or changes to ground levels.
  • Tree-sensitive construction methods.
  • Pruning requirements.
  • Tree protection measures during demolition and construction.
  • Whether further investigation such as root mapping is required.
  • Recommendations for monitoring or certification during construction.

City of Sydney’s current tree-report guidance provides detailed requirements for Arboricultural Impact Assessment reports, including information about tree condition, retention value, root protection areas, development impacts, mitigation measures and tree protection methods.

Who typically prepares an arborist report?

Development-related tree reports are generally prepared by a consulting arborist rather than a tree worker engaged primarily to carry out pruning or removal.

The qualification required can vary between councils and projects, so always check the relevant council requirements before appointing a consultant.

For example, City of Sydney currently states that it accepts tree reports prepared by consultant arborists with an Australian Qualifications Framework Level 5 arboricultural qualification or equivalent.

Other councils also specify qualification requirements for particular reports. These requirements should be checked rather than assuming the same qualification standard applies everywhere.

What to consider when choosing an arborist

Before requesting a quote, check exactly what type of report your council, development consent or project documentation requires.

It is worth checking:

  • Whether the arborist’s qualification level meets the requirements of the relevant council or consent authority.
  • Whether they regularly prepare reports for development applications and projects of a similar type.
  • Whether the proposed scope covers all trees that the council requires to be assessed, including relevant neighbouring or street trees.
  • Whether they have been supplied with current architectural, survey, landscape, stormwater and other relevant project drawings.
  • Whether a Tree Protection Plan is required as part of the report or separately.
  • Whether root mapping or other additional investigation could be required.
  • Whether construction-stage monitoring or certification by a project arborist may be necessary.
  • Whether revised plans will require the arborist to update the assessment.
  • The consultant’s professional indemnity and public liability insurance.

City of Sydney advises that consultant arborists preparing reports should carry professional indemnity and public liability insurance and notes that report costs can vary according to the report type, scope and number of trees assessed.

Related terms and services

The terminology can vary according to the council, consultant and purpose of the assessment. You may encounter:

  • Arborist report
  • Arboricultural report
  • Arboricultural Impact Assessment (AIA)
  • Arboricultural assessment report
  • Tree assessment
  • Tree risk assessment
  • Tree Protection Plan (TPP)
  • Tree protection specification
  • Tree Protection Zone (TPZ)
  • Structural Root Zone (SRZ)
  • Preliminary arboricultural report
  • Root mapping assessment
  • Pruning specification
  • Project arborist

These terms are not necessarily interchangeable.

An Arboricultural Impact Assessment is specifically concerned with the likely impact of proposed development on trees, while other arborist reports may address matters such as tree condition, risk, pruning or removal.

Frequently asked questions

What is an arborist report?

An arborist report is a professional assessment of a tree or group of trees.

Depending on its purpose, it may document tree species, dimensions, health, structural condition and other characteristics and provide recommendations about management, protection, pruning or removal.

For development projects, the report may also assess how proposed works are likely to affect trees and recommend measures to minimise those impacts.

What is an Arboricultural Impact Assessment?

An Arboricultural Impact Assessment, commonly abbreviated to AIA, is a development-related tree report.

It assesses how proposed works may affect trees and generally identifies trees for retention or removal, considers potential impacts on root and canopy areas, and recommends measures for managing or protecting trees throughout the development.

City of Sydney describes the AIA as the main tree report associated with a development application and states that it should objectively assess impacts rather than argue for or against the development.

Is an arborist report always required for a development application?

No.

Whether one is required depends on the development, the trees involved and the requirements of the relevant council or consent authority.

It may be required where proposed construction, excavation, pruning or other works could affect trees on the site, neighbouring land or public land.

Always check the specific development application requirements applying to the property.

Do I need an arborist report to remove a tree?

Not necessarily.

Tree-removal rules vary substantially between councils and can depend on factors including the tree, location, applicable planning controls and reason for removal.

A council may be able to determine a straightforward tree application without a report, while other circumstances may require an arboricultural assessment or additional evidence.

Do not commission an Arboricultural Impact Assessment simply because a tree is proposed for removal unless that is the report actually required.

What is a Tree Protection Zone?

A Tree Protection Zone, commonly abbreviated to TPZ, is an area around a tree intended to help protect the tree and its root environment from development impacts.

Importantly, it is not simply the area underneath the visible canopy. Development activities such as excavation, changes in ground level, paving, services and construction access can affect tree roots beyond the canopy area.

The size and treatment of a protection zone should be assessed by the relevant arboricultural professional for the project.

What is a Structural Root Zone?

A Structural Root Zone, or SRZ, relates to the area around the base of a tree that is important to its stability.

Development or excavation within this area can have significant implications for the tree, so proposals affecting an SRZ may require detailed arboricultural assessment and changes to the proposed design or construction method.

What information should I give the arborist?

For a development-related assessment, provide the arborist with the most current project information available.

This can include architectural plans, surveys, landscape plans, engineering or stormwater plans and any council correspondence or development application requirements relating to trees.

City of Parramatta specifically advises that consulting arborists should be provided with current relevant project documentation so the Arboricultural Impact Assessment is site-specific.

Should I engage an arborist before the design is finished?

For developments involving significant existing trees, obtaining arboricultural advice early can be useful.

City of Sydney’s current guidance recommends considering trees early in the planning process and describes a preliminary arboricultural report that can identify constraints and opportunities before the design is finalised.

This can help the project team understand tree-retention and protection issues before major design decisions have already been made.

NSW guidance and sources

Tree controls and arborist-report requirements vary significantly between councils. Always check the rules and development requirements applying to the particular property.

  • City of Sydney — Tree guidelines for pruning, reporting and using an arborist

    Current council guidance explaining consultant arborists, report types, qualification requirements, Arboricultural Impact Assessments, Tree Protection Plans, root-zone assessment and development-stage tree management. Read the guidelines (PDF)

  • City of Sydney — Check the document requirements for your planning application

    Provides guidance on when an arborist report may need to accompany a development application, including proposed works affecting trees on or near a site. Check document requirements

  • City of Parramatta — Trees and Development

    Provides another NSW council example of when an Arboricultural Impact Assessment and Tree Protection Plan may be requested and explains the importance of providing the arborist with current development plans. Read Trees and Development