When Two Arborist Reports Disagree: How Melbourne Councils and VCAT Resolve Conflicting Evidence

Conflicting arborist reports are more common in Melbourne planning matters than most people outside the industry realise. A property owner commissions a report that recommends tree removal as part of a development. A neighbour objects and presents a report from a different consultant reaching the opposite conclusion. Council obtains its own independent assessment. By the time the matter reaches any formal decision point, there may be two or three sets of arboricultural findings on the same trees, each prepared by a qualified consultant but arriving at materially different conclusions.

This creates real difficulty for decision-makers, and understanding how councils and VCAT work through conflicting arboricultural evidence is useful for anyone involved in a planning matter where tree assessment is a central issue.

Why Two Qualified Consultants Can Reach Different Conclusions

Two arborists assessing the same tree can legitimately arrive at different condition ratings, different significance assessments, and different recommendations without either of them necessarily acting improperly. Tree assessment involves professional judgement applied to observable evidence, and different consultants can weigh the same observations differently within the range of accepted professional practice.

The more problematic category of conflicting reports is where the difference in findings appears to reflect the instructing party's preferred outcome rather than a genuine difference in professional judgement. A report commissioned by a developer seeking to remove a tree and a report commissioned by an objector seeking to retain it may both be technically defensible in isolation but arrive at conclusions that conveniently align with whoever paid for them. Decision-makers at council and VCAT are experienced in identifying this pattern.

How Council Officers Handle Conflicting Reports

When a planning application generates conflicting arboricultural evidence, council officers have several options for resolving the conflict. The most common response is to refer the matter to the council's own arborist or to engage an independent referral assessor to review both reports and provide a third-party opinion.

The referral assessor will typically review the methodology used in each report, the site data each consultant collected, the consistency of the findings with observable site conditions, and whether the recommendations are proportionate to what the evidence actually shows. A report whose findings are clearly grounded in documented methodology and direct site observation is in a stronger position under this kind of review than one where the reasoning is thin or the conclusions extend beyond what the evidence supports.

Council officers will also consider the qualifications of the consultants who prepared the competing reports. A report prepared by a consultant holding AQF Level 5 arboriculture qualifications who followed a documented visual tree assessment methodology consistent with AS 4970 carries more procedural weight than one prepared by a consultant whose qualifications or methodology are less clearly documented.

Our tree reports and arborist assessments are prepared with referral review in mind, because a report that cannot withstand independent scrutiny is not a report that serves its purpose in a contested planning matter.

How VCAT Assesses Conflicting Arboricultural Evidence

At VCAT, conflicting arborist reports are assessed as competing expert evidence within a formal legal process. Tribunal members are not arboricultural specialists, and their role is to determine which evidence is more credible, more methodologically sound, and more directly responsive to the planning questions the tribunal needs to resolve.

Each consultant who prepared a report may be required to give evidence at the hearing and to be questioned by the other parties or their legal representatives. This process tests the consistency of the report's findings, the rigour of the methodology, and the independence of the consultant in a way that a council assessment stage does not. A consultant who cannot clearly explain and defend their methodology under questioning, or whose findings appear to have been shaped by the instructing party's preferred outcome, will not be a credible witness.

Tribunal members will also consider whether the reports actually address the same questions. A report focused on the tree's condition and retention value may not directly engage with the specific planning controls the tribunal needs to apply. A report that speaks to both the arboricultural findings and their implications for the specific planning questions before the tribunal is considerably more useful as evidence.

The Role of Independent Methodology in Resolving Conflicts

The single most important factor in determining which of two competing arborist reports carries more weight is the independence of the consultant who prepared it. A consultant with no commercial interest in the outcome of the planning matter, no removal or maintenance work to gain from a particular finding, and no prior relationship with either party that could compromise their objectivity, is in the strongest possible position when their evidence is weighed against a competing report.

Arborplan operates solely as a consultancy with no involvement in tree removal or maintenance works. There is no commercial incentive that could be identified or implied as influencing our findings. When our arboricultural evidence is placed alongside a competing report from a contractor who also performs the works their report recommends, the independence of our assessment is not a minor detail. It is the foundation on which the credibility of our findings rests.

Where our council arboricultural services are engaged to review or respond to a competing report, we approach that task with the same methodological rigour as our original assessments, because the strength of the response depends on the same qualities that make the original report credible.

What Happens When Root Investigation Data Is Part of the Evidence

In contested matters where the condition of the root system is relevant, the presence or absence of root investigation data can be a decisive factor in how conflicting reports are resolved. A report that makes recommendations about construction impact on tree roots based on calculated estimates is in a materially weaker position than one that bases those recommendations on direct subsurface evidence gathered through a non-destructive root investigation.

Physical evidence of root depth, density, and location is considerably harder to challenge at council or VCAT than recommendations derived from surface-based assumptions. Where a competing report relies on calculated estimates and our report is supported by direct investigation data, the evidentiary difference is significant and is generally recognised as such by council officers, referral assessors, and tribunal members.

Minimising the Risk of a Conflicting Report Undermining Your Position

For anyone involved in a Melbourne planning matter where arboricultural evidence is likely to be central, the best protection against a competing report undermining your position is to ensure the original report is as methodologically robust and independently prepared as possible. A report that is thorough, clearly documented, grounded in direct site evidence, and prepared by a consultant with unimpeachable independence is the most defensible starting point regardless of what a competing report may say.

Commissioning supplementary root investigation data where root conditions are relevant, and ensuring the report directly addresses the specific planning questions at issue rather than only the general arboricultural findings, further strengthens the evidentiary position.

Arborplan prepares tree assessment reports and arborologist reports for Melbourne planning matters where arboricultural evidence is likely to be tested, reviewed, or placed in competition with other expert opinion. If you are involved in a planning matter where conflicting arboricultural evidence is a concern, contact us to discuss how we can support your position.