1. Sustainable Production Forestry THE JOINT FORCES OF CSIRO & SCION Development of a productivity Index for Douglas-fir Leith Knowles

2. THE JOINT FORCES OF CSIRO & SCION Productivity Indices Site Index (SI) SI=MTH@40years. Independent of silviculture Site basal Area Potential (SBAP) Derived from sample plots. The SBAP is the value that makes the growth model BA increment best match the sample plot BA increment. The overall plot mean SBAP is calculated as the period- weighted mean over all increment periods. Independent of silviculture Is it possible to develop one simple volume index by combining the two?

3. THE JOINT FORCES OF CSIRO & SCION Methods TSV=a*MTH*BA TSV=a*SI b *SBAP c MAI =TSV/rotation age

4. THE JOINT FORCES OF CSIRO & SCION SI and SBAP for 1365 sample plots

5. THE JOINT FORCES OF CSIRO & SCION SI and SBAP matrix minmaxintervalNumber SI20m40m4m6 SBAP1.02.40.28 48

6. THE JOINT FORCES OF CSIRO & SCION

7. What is 500 Index?  500 index is simply the predicted MAI of a stand planted at 1500 stems/ha, thinned to 500 stems/ha by 15m MTH, and grown to age 40 years

8. THE JOINT FORCES OF CSIRO & SCION Results 500 Index = a*SI b *SBAP c Where a=0.0971 b=1.344 c=0.0973

9. THE JOINT FORCES OF CSIRO & SCION 500 Index compared to MAI from DF NAT

10. THE JOINT FORCES OF CSIRO & SCION SBAP can be predicted from SI and 500 Index SBAP=(500 Index/a*SI b )) d Where a=0.0971 b=1.344 d=1.028

11. THE JOINT FORCES OF CSIRO & SCION Sensitivity of 500 Index to changes in silviculture  Stocking @ age 10 years (1500 stems/ha) 200 stems/ha=1% change in 500 Index  MTH at thinning (15m) 1m=1.15% in 500 Index  Final crop stocking (500 stems/ha) 100 stems/ha=6.6% in 500 Index

12. THE JOINT FORCES OF CSIRO & SCION Latitude abc 38 0 S 1.0001.3440.973 42 0 S 0.0971.3440.973 46 0 S 0.0941.3440.973

13. THE JOINT FORCES OF CSIRO & SCION 500 index can be estimated by region

14. THE JOINT FORCES OF CSIRO & SCION ….. and by forest

15. THE JOINT FORCES OF CSIRO & SCION Conclusions  Both SI and SBAP are needed to explain site productivity  These can be combined to predict MAI for a standard regime (500 Index)  Productivity of Douglas-fir on most sites in NZ is now expressed in terms of 500 Index  500 Index included in DF Calc V2

16. THE JOINT FORCES OF CSIRO & SCION Questions and answers