New Zealand doesn't have its own dedicated national standard for tree assessment on development sites, the way the UK has BS 5837 or Australia has AS 4970. What fills that gap in practice is two things: each council's own District Plan rules on protected and notable trees, and — because there's no local equivalent — many New Zealand arborists reference AS 4970-2009 informally as the closest available technical framework for Tree Protection Zone calculations.
The District Plan is where the actual rules live
Whether a tree is protected at all, what diameter or trunk girth triggers a resource consent requirement, and what an applicant has to submit to remove or work near a protected tree are all set at the council level — Auckland's Unitary Plan, Wellington's District Plan, and Christchurch's District Plan each have their own thresholds and their own definitions of "significant" trees. A national-style checklist doesn't substitute for reading the specific plan a site sits under.
Borrowing AS 4970's method, without the New Zealand-specific backing
Because there's no NZ-specific TPZ formula, most practitioners apply the AS 4970 method — trunk diameter × 12 for the protection radius — as a reasonable, defensible calculation rather than a legally mandated one. Council arborists generally accept this in the absence of anything else, but it's worth stating plainly in a report that the calculation is drawn from the Australian standard by convention, not because New Zealand requires it. That one sentence heads off a reviewer's question before it's asked.
What actually gets checked
A resource consent reviewer is checking whether the tree in question meets the District Plan's own definition of protected/notable, whether the assessment methodology is stated and consistent, and whether any proposed works near the root zone are backed by an arborist's reasoning rather than asserted. Because there's more interpretive room here than in a jurisdiction with a binding national standard, being explicit about method and assumptions matters more, not less.
This isn't legal advice — always check the specific District Plan for the site. tree·canopy keeps the survey record and the stated methodology together, so a report can show its working when a council reviewer asks how a number was reached.