Ask Your Mates Open Forum

Useful Life of Tree Cells

  • 1.  Useful Life of Tree Cells

    Posted 17 September 2018 21:33

    Are there are any councils out there that are currently capitalising Tree Cells and if so, what useful life, you are using?

    We currently capitalise our trees at a single rate as one of two grouped financial assets 'Street Trees or 'Park Trees' with a useful life of 100 years. We would like to consider other tree valuation treatments but we are currently undertaking comprehensive audits of trees in a our major parks and won't make any decisions until those audits are completed over the next few years.

    Complete installation (planting) costs have been taken up against the tree asset to date but as we are using more and more tree cells in our footpath and car park areas I am starting to recognise the tree cells as their own assets and considering that the majority of the installation cost is associated with the tree cell rather than the tree I want to recognise the value and life of the tree cell separately to the tree and bring them out of a single grouped financial asset and capitalise the operating asset.

    I could easily support a useful life of 100 years in accordance with the useful life that our finance department and auditors are okay with for the tree assets to date. However, in reality the majority of our trees (street trees in particular) do not last 100 years. The manufactures of the tree cells we have used to date suggest these would have a life in accordance with it's construction material of 150+ (but we will not substantiate this until cells have been proven in situ for that actual life). My concern is the likelihood of the tree dying during the first 5, 10, 15 years of planting and the roots are established well enough that we can't re-use the tree cells and both the tree and cells will require renewal. So I am considering a shorter asset useful life that can be re-assessed at the say 10 oor 15 years that can be extended upon assessment and condition rating.

    I am trying to determine an appropriate useful life that would be appropriate for depreciation and the average life that can be expected.

    I would appreciate any comments or advice.



    Kristi Cohen I Parks Asset Officer
    Asset Management & Delivery I Infrastructure Services I City of Launceston


  • 2.  RE: Useful Life of Tree Cells

    Posted 18 September 2018 21:16
    Hi Kristi,
    Thats a really interesting question - you should try and attend the upcoming IPWEA Parks Seminar in late Oct/early Nov, where we will be exploring the approach to living asset valuations. It is still an area where the industry is still developing what best practice should be.
    I hadn't yet though about valuing tree cells separately from the tree and my initial inclination would be to include with the value of the tree as would assume their lives would effectively be the same - but would be good to discuss this further. This also supports our general advice of trying to keep valuation approach as simple as possible.
    A 100 year life is common for park trees but 60 years would be more typical for street trees.
    Good to hear that your accountants and auditors are accepting the inclusion of trees in your Councils valuation reporting.

    2018 park seminar venues and dates:

    Brisbane 29 Oct

    Sydney 30 Oct

    Adelaide 31 Oct

    Melbourne 1 Nov

    Perth 8 Nov

    Register via this link

    Brian Milne
    Ph 410 263 121


  • 3.  RE: Useful Life of Tree Cells

    Posted 20 September 2018 01:08
    ​Digging back in the memory cells there was a session on replacing sleepers for a normal train track.  The timber sleepers crumbled over a period of time say 40-70 years and the inspector then replaces the sleepers that have gone rotten and leaves the okay ones until they fail.  He needs an annual budget for replacement that reflects this natural occurrence. Now for concrete sleepers the time to failure was short and sharp and they described it as a special type of graph to failure.  So a different annual budget is required as the sleepers all start failing about the same time. Someone like CSIRO had a research program that drew up the time to failure  for timber and concrete sleepers.

    For the tree asset register I think you would have to develop a similar graph for each type of vegetation.  Maybe set up a series of classes of vegetation.  No matter what the time to failure is very much a rule of thumb so the classification should be as simple as possible,  I think that is how I would do the valuations and life expectancies.   Set budgets to reflect what happens and they shouldn't be set to coincide with election times.

    John Keays

    John Keays
    Keays Software
    Brisbane Queensland