NGIA to request a review of AS2303:2015 Tree Stock Standard

The Australian Standard, Tree stock for landscape use (AS2303:2015) was released in April 2015.

The development of the standard took some time and saw some issues of contention, the primary issue being around the use of tree stock balance assessment. This concept and process was influenced by the previously published “Specifying Trees - A guide to assessment of tree quality” (R. Clark, 2003) also commonly known as NATSPEC.

At the drafting of the standards there remained some doubts as to the validity of tree stock balance assessment, as there was limited validation of it worth as demonstrated through independent scientific assessment. Because of this, the treestock balance parameters were included into the standard as Informative elements only. Informative portions of the standard are included for information and guidance only and do not form part of the standard. In other words a tree can be compliant with the standard without meeting the tree stock balance assessment.

At the time of publishing NGIA, on behalf of industry, undertook a commitment to conduct further research of tree stock balance parameters to either validate or disprove the basis for the calculations as applied to the range of species, production practices and climatic conditions across Australia. This research was intended to be completed within two years of publication of the standard, and the data from this research considered in a review of the standard at that time.

This research has been undertaken on behalf of industry by Western Sydney University (WSU) as part of an industry levy funded project (NY15001) and is now nearing its completion. Over the course of the last year more than 13,800 trees were evaluated against the tree stock balance assessment. This included; 159 species in varying pot sizes and life stages, across 23 production nurseries, and covered all mainland states in Australia across a variety of climatic conditions.

Initial indications from the data obtained during this study would suggest that size index as determined by the tree stock balance assessment is not reflective of good quality trees grown around Australia, considering the influence of climate, species and production practices. This research conducted by WSU will be released to industry after the conclusion of the project in April.

NGIA is planning to submit a request to review the standard based upon the research undertaken by Western Sydney University.

For information on the tree stock project and the research conducted visit https://www.westernsydney.edu.au/hie/research/research_projects/tree_stock_standard.