An updated edition of the Australian Standard “Tree stock for landscape use” will be released publicly on 21 December 2018.
This publication represents over 18 months of negotiation and hard work by the Standards Australia EV018 committee, and input from numerous key stakeholders and industries.
Originally released in 2015, this revised edition incorporates data from a nursery levy funded project conducted by Western Sydney University in 2016/17 which sampled 23 wholesale nurseries capturing data on nearly 14,000 containerised trees including 159 tree varieties.
A key focus of the project was to quantify the influence of species and climatic region on root to shoot balance of nursery tree stock and enable an evaluation of the tree stock balance assessment criteria within the 2015 version of the standard, where it was noted that industry would undertake further R&D to clarify the importance of tree stock balance parameters. The project report findings indicated that “the specified range of Size Index in relation to container volume in AS 2303 did not adequately capture the natural variation across the large diversity of ‘ready for dispatch’ trees in Australian nurseries”.
In order to better depict the range and spread of values, a population graph was developed which plotted population percentiles against size index and container volume (L). In other words, at a glance one can quickly see how a tree compares against trees at the same container volume/size index. The graph has key population percentile bands at 5, 25, 75 and 95%, which indicate where an individual tree sits in comparison to the rest of the tree population. For example, a tree sitting above the 95th percentile is greater than 95% of the population of like trees.
Like the previous edition, the size index requirements are informative only, meaning that a tree does not have to meet a specific size index requirement for it to be compliant with the standard. The new appendix suggests that an optimum value for tree stock balance should be the 50th percentile, and that stock should fall within the preferred range of between the 25th and 75th percentile for a given container volume. It also notes that values between the 5th and 95th percentiles are acceptable with consideration and explanation. Size index values should not exceed those values outside of the 5th and 95th percentiles.
Industry representative on the EV018 committee, NGIA Program Manager Chris O’Connor, notes that “This new release represents a much more useable standard. It supports both purchaser and grower decision making by comparing their tree to a real-world population of trees grown in Australian nursery conditions. It is a great example of how applied R&D can be used to better the industry and I encourage the industry to get behind such endeavours.”
Chris recommends growers who are growing tree stock to purchase a copy of the standard to ensure that they become familiar with it and benefit from it.
“Many tree stock purchasers now require stock which conforms with AS2303.”
“The standard also demonstrates professionalism within industry and supports the concept of high quality tree stock which is needed to continue the advocacy for increased urban greenspace”.
Chris also cited that “The input of knowledge and experience from a wide range of industry tree stock growers was certainly invaluable in developing this amended standard and special mention must be made of fellow EV018 committee members and NGIA members Mr Tony Green from Andreasen’s Green and Mr Ross Clark from Trees Impact. Both gentlemen had significant input into the standard and their assistance is certainly valued and appreciated. Likewise Professor Mark Tjoelker and his team from Western Sydney University were invaluable not only through the research that they conducted but also through aiding the industry in seeing that research translated into a tangible outcome for industry in the guise of the standard”.
The updated tree standard will be available for purchase after 21 December 2018 through https://infostore.saiglobal.com/store/