|Question On Notice No. 1900 asked in the Legislative Council on 12 March 2019 by Hon Diane Evers |
Question Directed to the: Minister for Environment
Minister responding: Hon D.J. Kelly
Parliament: 40 Session: 1
(1) I refer to the 2004-2013 Forest Management Plan, particularly the relationship between the timber yield from cut-over coupes versus the predicted yield, and I ask at what stage in the planning of timber harvesting operations is the timber yield by species and log grade from cut-over coupes predicted?
(2) What procedures and methodology are employed to estimate predicted timber yield?
(3) Does the Government keep records of the timber yield by species and log grade from cut-over coupes versus the predicted yield from those coupes?
(4) Does the Government keep any shortfalls or under-predictions under cumulative review:
(a) if no to (4), why not?
(5) If yes to (4), if the results of any cumulative review indicate a trend to over-prediction, will the Government require a review of the sustained yield contained in the Forest Management Plan:
(a) if no to (5), why not?
Answered on 11 April 2019
I am advised that the forest management plan referred to should be the Forest Management Plan 2014-2023.
(1) Initial estimates of timber yields by species and log grade were prepared as part of the strategic woodflow scheduling undertaken during preparation of the Forest Management Plan 2014-2023. These estimates may be refined as coupe boundaries are adjusted or field reconnaissance occurs as part of the preparation of harvest plans.
(2) The procedure and methodology for predicting timber yields differs between species. Predictions are based on available data relating to a range of matters such as historic yields (for areas of similar forest and operation type), timber inventory, silvicultural history, and modelled log specifications and utilisation practices. The methodology and inventory systems are described in the Sustained Yield Information Sheet series and discussed in the Calculating the Sustained Yield for the South-West Native Forests of Western Australia report by the independent expert panel, which reviewed the sustained yield calculations.
(4) and (4)(a) A forest-wide cumulative review of timber removals against predictions is not undertaken on a continuous, coupe-by coupe basis. This is because short-term, localised operational factors and product requirements can create considerable variability and confound the more important longer-term trends over the 10-year period of a Forest Management Plan.
A comprehensive review of predictions is performed as part of the calculation of the sustained yield estimates for each Forest Management Plan. It is undertaken in this manner because a large sample size of coupes is required to meaningfully reconcile the variability in log removals against yield estimates for the range in forest type, silvicultural history, and operation type across the forest. This approach was endorsed by the independent expert panel and means any cumulative net bias in the estimates (to over or under predict) is taken into account in calculating the sustained yields for the next plan.
(5) Not applicable.
(5)(a) Refer to (4) and (4)(a).