Australian Standard AS2303:2015 revision open for public comment

The Australian Standard AS2303 was initially released in 2015 following an extensive period of consultation with industry and a broad range of stakeholders including; local government, arborists, landscapers landscape architects and academia.
One area which was still under debate was the concept of size index which had previously been developed under the NATSPEC publication Specifying Trees. Under the initial release of AS2303 industry undertook a commitment to explore and support further research in this area. This research was realised through a levy funded project (NY15001) conducted by Western Sydney University (WSU).

Along with an international literature review, the WSU research project recorded nearly 14,000 trees across 159 varieties and 23 nurseries across Australia between April 2016 and January 2017. Each tree was first assessed against the normative elements of the standard and only those trees which first complied with the normative elements of the standard were measured for their size index.

The research conducted by WSU concluded that the current specified range of size index in relation to container volume in AS2303 did not adequately capture the natural variation across the large diversity of ready to dispatch trees in Australian nurseries. This result prompted the review into the current standard by the EV018 Standards Australia committee which includes representatives from key stakeholders including the Nursery Industry, which was represented by Tony Green (Andreasens Green) and Chris O’Connor (NGIA). Following 12 months of discussion and negotiation a draft revision has been developed.

Several minor changes have been incorporated into the revision, however the most significant change to the standard is centred around the tree stock balance appendices (D & E). These have been replaced by a single appendix. At the heart of the new appendix are two graphs and accompanying tables which reflect the Australian tree stock population data captured during WSU’s research. The tables are in an easy-to-use format and enables growers and specifiers to compare their trees to a real-world population of tree stock. An example of the table for 18-100L stock can be seen in the attached image.

A preferred size index range of between 25% and 75% of the tree population at any pot size is suggested. Tree stock with size index values falling outside this preferred range, but within the 5th and 95th percentiles for a given container volume, should not automatically be deemed non-conformant with size index, however an explanation should be recorded. Size index values should not fall below the 5th percentile or exceed the 95th percentile.

It is important to note that this appendix remains informative only, i.e. for a tree to comply with the standard it does not need to comply with any aspect of this appendix. The appendix will however provide a common system for those specifiers still requiring a size index assessment.

Public comment on the draft standard closes on 6th of August 2018.

To access a copy of the draft revision, visit:

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Specific terms are used in standards which provide clarity and consistency across standard documents some commonly used examples are below

  • Should – meaning “it is recommended that” or “ought to”
  • Shall – meaning “is to”, “needs to” “is required to”
  • Normative - meaning mandatory
  • Informative – meaning additional information that complements the user’s understanding