[ASC-media] CSIRO and Ensis: Computer model helps foresters boost wood yields

Rebecca.Eveleigh at csiro.au Rebecca.Eveleigh at csiro.au
Fri Sep 7 07:46:12 CEST 2007

7 September 2007
Ref: 07/175

Computer model helps foresters boost wood yields

The findings from a major study into applying fertiliser to radiata pine
forests have been used to create a computer model that helps forest
managers increase both the yield and profitability of wood production.

The decision support system has been developed by scientists from Ensis
funded by the Forests and Wood Products Research and Development
Corporation (FWPRDC) in collaboration with Auspine, ForestrySA and Green
Triangle Forest Products. It is based on data from experiments carried
out over 12 years at 16 sites in the Green Triangle region in South
Australia and Victoria.

The computer model integrates the results from these experiments to
predict the growth response and profitability of different rates, forms
and application scenarios for nitrogen and phosphorous fertiliser. The
goal is to help forest managers maximise wood production or profit.
While simple too use, the system is underpinned by a detailed scientific
understanding of the key processes influencing soil nutrient supply and
how this drives tree growth.

Inputs for the model include basic information such as stocking, age,
volume and site quality while outputs include graphs of annual or
cumulative response, harvest yield, actual and discounted fertiliser
costs and indications of harvest revenues.

Ensis Forest Scientist Dr Barrie May, who helped develop the decision
support system, says it gives forest managers a simple, user-friendly
tool to rapidly and automatically identify the optimum fertiliser
strategy for a particular site as well as a way to compare relative
growth responses and profitability across multiple sites. 

"Overall it provides a means to substantially improve fertiliser
efficiency by targeting stands that will respond to fertiliser
application and then highlighting strategies to boost growth and
maximise wood yield using fertiliser regimes," Dr May says.

Dr May says while the model is yet to be tested outside the Green
Triangle, he is confident many of its predictive capabilities will be
transferable, with appropriate customisation.

Results from the research underpinning the new computer model found that
growth over six years on plots fertilised with both nitrogen and
phosphorous increased by 8 to 28 m3 ha-1, compared with unfertilised
plots. An economic analysis showed that this translated to returns on
investment ranging from -2 per cent to 39 per cent as a result of the
increase in tree size which, in turn, boosted both the volume and unit
value of the wood produced.

"The findings show how the efficiency and profitability of fertiliser
application can be improved by targeting the most responsive sites and
tailoring fertiliser strategies to suit requirements of specific
stands," Dr May says.  

For example, he says, applying nitrogen to stands previously fertilised
with phosphorous increased the average stand value by almost double
compared with applying nitrogen (N) alone to unfertilised stands. The
findings have also shown that most sites in the Green Triangle do not
respond to phosphorous (P) alone and there is little benefit in applying
P more frequently than once every ten years at most sites. 

Dr May says the number of sites tested and the detailed information
gathered at them since the mid 1990s make the research one of the
largest and most significant long term studies of response to fertiliser
and N and P cycling ever carried out in Australia.

The findings have delivered other valuable information including
evidence that some forms of nitrogen are more effective than others. Dr
May says responses to nitrogen applied as urea were significantly lower
- on average around 30 per cent - than ammonium nitrate or ammonium
sulphate. However, certain forms of urea, such as agrotain urea, showed
promising results.

Dr May says foresters have, in the past, tended to assume fertiliser
application was straightforward but the research results prove

"If you choose the wrong fertiliser or wrong site, the trees may
actually grow more slowly than if you did nothing," he says.

"Furthermore, if you wait too long before thinning or clear felling
fertilised stands much of the early fertiliser response may be eroded as
a result of other factors limiting growth. However, the right
applications combined with the appropriate silviculture regime can lead
to a significant increase in wood production and, ultimately, greater
returns. There has been a lot of guesswork in the past - now we have a
means of quantifying the inputs and returns."

The full research report on applying fertiliser to radiate pine forests
will be available from www.fwprdc.org.au.  

Further Information:

Dr Barrie May
Forest Scientist, Ensis 

+61 8 8721 8120
0428 492 161
Barrie.May at ensisjv.com
Media Assistance:

Anne Lawrence
Marketing and Communications Manager, Ensis

+61 419 696 184
Anne.Lawrence at ensisjv.com

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Beck Eveleigh
Media Assistant
CSIRO Media Liaison
6276 6451
0409 395 010

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