Tree-specific risk assessment using contemporary methods such as QTRA (2005), TRAQ (2013) and VALID (2017) are relatively recent innovations; and they continue to evolve. The Minimum Industry Standards (MIS) series is an NZ Arb and Arb Aus collaboration to provide training resource materials and standards promoting the safety, quality and consistency of arboricultural endeavours. The second edition of MIS501 is a work in progress. Its purpose is to introduce and acknowledge the most used methods. There has also been development of a new system to address areas of new approaches to tree risk assessment. This will be peer reviewed and presented to the Boards of Arboriculture Australia and New Zealand Arboriculture for approval prior to introduction

The proposed new method aligns to ISO 31000 and IS0 45000 (Occupational Health and Safety). It does this firstly by segregating risk from trees into Risk of Harm and Risk of Loss; and risk to trees – their value - as Risk to Benefit.

Risk of Harm is semi-quantitative method based on well-defined categories for consequence (Negligible, First Aid, MTI/Minor, LTI/Serious, Fatality). These categories, consistent with broad industry practice and aligning with both ISO 4500 and incident reporting requirements under local legislation, support the client. Risk of Loss (asset damage) is a quantitative method with an optional 5 x 5 risk matrix representational output. Risk to benefit is, similarly, a quantitative method, differing from the others in that it does not require an occupancy input and is not time constrained. This enables the articulation of, as examples, the benefits of formative pruning and significant tree retention, on a “risk” platform using risk language.

This presentation demonstrates how MIS501 2ndedition proposes to address the concerns of arborists that led to the AANZAA working group being formed.

The proposed new method will seek to do this, particularly around Risk of Harm, by: moving the risk language around trees from “fatality” to “injury” (it’s estimated there are 20 injuries to a single fatality) by using qualitative injury consequence levels (similar to TRAQ) rather than the single consequence of fatality utilized by quantitative methods; moving from the bespoke language of existing methods to client-familiar representation (the 5 x 5 risk matrix); quantifying in dollars the benefit and lost benefit from tree work (such as removal or pruning); assisting consistency by using arborist-aligned language (through focus group research and method-option capability); being open source and designed to be system-friendly, allowing for integration into 3rd party in-field data acquisition systems and customer management systems, facilitating efficient tree population risk assessment and effective use of casual observation reported by residents, for example; and finally, being free and adaptable.