Request to be made to alter tree stock standard

A request to review industry standard AS2303: 2015 Tree Stock for Landscape Use will be made this year, following new research that shows Australia’s landscape trees have a much greater variation than it allows.

The project Evaluation of nursery tree stock balance parameters (NY15001) has been carried out to provide additional data backing for the standard, often used by nurseries, councils and landscape architects to determine trees ready for dispatch are ‘fit for purpose’.

The team from Western Sydney University’s Hawkesbury Institute of the Environment recently concluded nursery visits, which involved collecting extensive tree measurements from 23 wholesale nurseries across Australia.

Over 13,000 trees were measured from a comprehensive list of species grown across a variety of climatic zones.

And the findings are in, suggesting that for those selecting the trees, there’s a strong possibility they are rejecting trees based on a standard that is too limited for real-world tree production.

With industry initiatives like the 202020 Vision championing the importance of green space in urban areas, there has never been a more crucial time to build a data backbone for the standard.

Key Findings

  • The specified range of Size Index in AS2303 does not adequately capture the natural variation in ‘ready for dispatch’ trees in Australian nurseries.
  • Small, non-native, deciduous trees in containers less than 50L tended to have greater Size Index values than native evergreen trees.
  • Small to medium trees in containers 50 to 500L showed the greatest variability in Size Index which is mostly due to the differences in species.
  • Larger trees in containers over 500L typically had a smaller Size Index range than the current standard.
  • About one-third of trees measured fit within the current standard’s data range across all container sizes of 18 to 3000L.
  • 45% of trees measured fall under the acceptable minimum limits of the current standard.
  • 23% of trees measured fall over the acceptable maximum limits of the current standard.
  • The differences between species was more important than climatic or nursery differences in explaining the variation in Size Index.
  • Tree height was much more variable than calliper diameter in the measured trees.

Next Steps

A final report on the findings is due to be provided to Horticulture Innovation Australia by the end of April 2017.

The project’s Steering Committee, which brings together nursery growers, key industry stakeholders and researchers, recently reviewed an interim report, and agreed for Nursery & Garden Industry Australia submit a request to review the standard this year, so as to ensure the standard takes into account the diverse range of species across Australia’s different climatic zones.

The submission will be focused around the need to review Size Index and tree stock balance equations based upon the research outputs from Western Sydney University.

Further discussion will be needed over coming months within both the nursery industry and those affected by any change, to determine the exact nature of proposed revisions to the standard text.

Project Code: NY15001

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