An arborist report and a tree survey are both professional documents produced by a qualified arborist, but they serve quite different purposes. In short, an arborist report digs deep into the condition and risk of one or a small number of trees, while a tree survey is a broader inventory that catalogues many trees across a property or development site. Knowing which one you need can save you time, money, and potential headaches with your local council.
What Is an Arborist Report?
An arborist report (sometimes called a tree assessment report or tree risk assessment) is a detailed written document prepared by a qualified arborist about a specific tree or small group of trees. It typically covers:
- Species identification and approximate age
- Structural condition — trunk, branches, root zone, and canopy health
- Risk assessment — likelihood of failure and potential consequences
- Recommendations — pruning, cabling, removal, or ongoing monitoring
- Retention value — whether the tree is worth keeping
Arborist reports are commonly requested by councils when you apply for resource consent to remove or work near a scheduled or protected tree. They are also used in property disputes, insurance claims, and pre-purchase property inspections. If a tree is close to a building or boundary and you're concerned about its safety, an arborist report gives you documented, professional advice.
What Is a Tree Survey?
A tree survey (also called a tree inventory or arboricultural survey) is a systematic catalogue of all — or a defined selection of — trees on a site. Rather than going deep on one tree, it goes wide across many. A typical tree survey records:
- Species and location (often mapped with GPS coordinates)
- Trunk diameter at breast height (DBH) in millimetres or centimetres
- Height and canopy spread
- General health and condition rating
- Retention category (e.g., retain, monitor, remove)
Tree surveys are most commonly required as part of a resource consent application, a subdivision, or a development project where the council needs to understand what trees exist on site before any earthworks or construction begins. Developers, architects, and landscape architects often commission tree surveys early in the design process so that significant trees can be designed around rather than removed.
Key Differences at a Glance
| Feature | Arborist Report | Tree Survey |
|---|---|---|
| Scope | One or a few trees | Many trees across a site |
| Depth | Detailed assessment | Broad inventory |
| Common use | Consent, risk, disputes | Development, subdivision |
| Output | Written report with recommendations | Schedule/map of all trees |
| Cost (guide only) | Generally lower | Can be higher for large sites |
Note: Costs vary significantly depending on site size, number of trees, and the arborist's time. Always get quotes from at least two or three qualified arborists.
When Do You Need Each One?
You likely need an arborist report if:
- You want to remove or prune a protected or scheduled tree and need council approval
- A neighbour's tree is damaging your property and you need documented evidence
- You're buying a property and want a professional opinion on a large or ageing tree
- A tree has been damaged in a storm and you need to assess whether it's safe
You likely need a tree survey if:
- You're planning a subdivision or development and the council requires a tree inventory
- You're a property manager responsible for trees across a large site (e.g., a school, body corporate, or commercial property)
- You're preparing a landscape plan and need to know what's already there
Some projects require both — for example, a development site might need a full tree survey first, followed by individual arborist reports on trees that are scheduled or at risk from construction activity.
NZ Regulations and Council Requirements
In New Zealand, trees on private land can be protected under a district plan as scheduled trees or through notable tree provisions. Before removing or significantly pruning any tree, check with your local council whether a resource consent is required. Requirements vary significantly between councils — what's fine in one district may require consent in another.
The MBIE Building Performance website is a useful starting point for understanding how trees interact with building consents, particularly where tree roots or canopies are near structures. For health and safety considerations when working around trees — especially near powerlines — WorkSafe NZ provides relevant guidance.
BRANZ also publishes research on how trees interact with buildings and foundations, which can be relevant when an arborist report is being used to support a building consent application.
What Qualifications Should Your Arborist Have?
In New Zealand, look for an arborist who holds a New Zealand Certificate in Arboriculture or equivalent, and ideally is a member of the New Zealand Arboricultural Association (NZAA). For reports that will be submitted to council, the arborist should be able to demonstrate relevant qualifications and professional indemnity insurance. Always ask to see their credentials before commissioning a report.
When to Call a Professional
Both arborist reports and tree surveys must be prepared by a qualified arborist — this is not DIY territory, especially when the documents are intended for council submissions or legal purposes. An unqualified report is unlikely to be accepted by a council planner and could delay your project significantly.
If you're unsure which document you need, start by contacting your local council's planning or resource consent team — they can tell you exactly what's required for your situation. You can also find qualified local arborists on tradedirectory.co.nz who can advise you before any formal engagement.
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