Solid timber recovery and economics of short-rotation small-diameter eucalypt forestry
This report was prepared for Future Forests Research Ltd (FFR) by Scion.
Dean Satchell, Sustainable Forest Solutions, R.D. 1 Kerikeri, Northland 0294. +64 9 4075525
James Turner, Scion, Private Bag 3020 Rotorua 3010. +64 7 3435899
Date: June 2010
Appendix 1: Assumptions in Discounted Cash Flow Analysis
Appendix 2: Prices and values of timber in New Zealand used for estimating board prices
Appendix 3: Timber grading
Appendix 4: Sawmilling methodology
Appendix 5: Glossary of terms
Spreadsheet 1: Kaingaroa Compartment 1194 E. regnans economic value (Microsoft Excel macro-enabled workbook 3.6 MB)
Spreadsheet 2: Optimal rotation and stocking for E. regnans (Microsoft Excel macro-enabled workbook 864 KB)
Treegrower article »
Appendix 3: Timber grading
Interpretation of the Australian Standards AS 2796.2 – 2006 was to the following specifications:
- Grading was undertaken on blanked, but not finished-to-profile timber.
- Timber not meeting the grade standards due to decay, knots or branch defects was classed as "Box".
- Timber was graded to lengths which were determined to be points appropriate for simulating docking. These lengths met the grade standards and were free of Box, end-splits, collapse, skip and wane. Short lengths of timber (Clear Cuttings) were graded according to AS 2796.2 – 2006 on all surfaces to Select grade or better.
- Lengths docked for Box (including decay, knots, branch defects), wane (including want, wane and skip), collapse and end-splits were recorded.
- End-splits were measured inclusive of end-checks.
- Surface checks were recorded in number according to average length. There was no assessment of internal checks.
- Where checks were grade-limiting this section of the board was classed as "Box". (This was rare and mostly associated with branch defects).
- Collapse, skip and wane were not recorded where these appeared to be within limits for further profiling to finished dimension (Table 2).
- Where collapse, skip, want or wane were present, the length of the section of the board meeting grade was estimated based on the finished profile (Table 2).
- Mechanical damage was ignored. Very little damage was present, despite the trees having been harvested for pulpwood. Two logs had a small amount of want (a grade-limiting defect) which was ignored when grading to avoid influencing recovery results for these diameters. It was assumed that logs harvested for sawlogs would not be damaged significantly by harvesting equipment. However this may need verifying.
- Skip or wane were not included in recovered sawn volume where present on the end section of a board.
- Branch defects included (but were not limited to) voids associated with bark encasement (where knots were not loose) and over-size of knots.
- Loose knots and decayed knots were assessed as holes where > 10 mm.
- Discolouration (incipient decay) that had no softness was classed as feature and did not influence grade. This was rare.
- Spike knots were not specifically covered in the Australian standard, so that where they were encountered they would almost always be larger than knot allowances permitted based on piece width. Where they could be placed on the reverse face the standard's allowance of 20% KAR for holes on the concealed surface was applied. This also potentially provided for flooring to meet strength requirements.
- Knots and 'associated voids' (voids were not defined in AS 2796.2 – 2006) was difficult to interpret, so the void was defined for our grading based on the allowance for hole diameters.
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