Model Comparison for short-term growth projections on a

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Model Comparison for short-term growth projections on a Western Oregon property GMUG Meeting June 2, 2010 Natural Resource Consultants Since 1921

G&Y Models Survey • 15 Respondents (Industry + TIMOs + Consultants), multiple responses allowed G&Y Model SPS/FPS FVS ORGANON In-House Other Excel DFSim Used 8 7 5 5 2 1 1 Percent 28% 24% 17% 7% 3% 3% * PACIFIC NORTHWEST TIMBERLAND INVESTMENT SURVEY RESULTS, MARCH 2010, SIZEMORE & SIZEMORE, INC. Natural Resource Consultants Since 1921 *

Data - Location • Western Oregon • South of Portland, North of Eugene • Stands in Valley & up west slope of Cascades Natural Resource Consultants Since 1921

Data - Remeasurement Count of Plots: Interval (Yrs) No Remeasurement No Thinned* Grand Total 0 16 2 18 3 2 2 4 1 1 5 17 6 2 2 7 2 2 8 3 3 9 1 10 52 52 13 1 1 Grand Total Natural Resource Consultants Since 1921 16 81 13 1 16 30 2 113

Data – Age & SI Count of Plots: Site Category Age Class HIGH MED LOW Grand Total 15 - 24 7 9 0 16 25 - 34 6 4 1 11 35 - 44 16 6 0 22 45 - 54 18 13 3 34 55 - 64 2 5 0 7 65 - 74 0 2 Grand Total 49 39 4 92 Natural Resource Consultants Since 1921

Site Classes Site Category Site Index Assigned SI* High Greater than 120 125 Medium Greater than 95 and less than or equal to 120 110 Low Less than or equal to 95 95 * Prior to 1997, SI class assigned based on growth rings Natural Resource Consultants Since 1921

Stand Statistics (Init) TPA BA QMD Avg Ht Ht 40 BFV Count 92 92 92 Mean 238 164 11. 7 74 87 20, 490 Min 75 17 5. 2 28 29 0 Max 620 289 20. 1 129 48, 129 Std. Dev 101 61 3. 5 24 27 13, 682 Std. Err 10. 6 6. 4 0. 36 2. 5 2. 8 1, 426 Std. Err. Pct 4. 4% 3. 9% 3. 1% 3. 4% 3. 3% 7. 0% Natural Resource Consultants Since 1921

Merch Specs Specification Value Minimum DBH 7 inches Stump Height 1 foot Log Length 32 feet Minimum Top DIB 5 inches Minimum Log Length 16 feet Log Rule Long Log Trees Must Contain 1 Full Log No Trim Amount 12 inches - fixed Use Scribner Decimal C No Hidden Defect 0 Natural Resource Consultants Since 1921

Tree Statistics • 4, 382 trees across 15 species – DF (3, 469), WH (604) Natural Resource Consultants Since 1921

Growth Models • SIS (SPS) • FPS (v 6. 73) • FVS (12/16/2008) – PN, WC • ORGANON (v 8. 2) – NWO, SMC Natural Resource Consultants Since 1921

Growth Models - Options • SIS (SPS) – Client coefficient file • FPS – Library 11 • FVS – Max SDI: DF 600, WH 720, RA 300 • ORGANON (v 8. 2) – Max DF SDI = 600 Natural Resource Consultants Since 1921

Comparison Methods • Measured vs. Predicted Average Growth • Basic Error Statistics • Error CDF’s • Error Significance Tests • Linear Regressions of Errors • 50 -Year Growth Projections Natural Resource Consultants Since 1921

Comparison Caveat • Period length is not uniform across plots • The same set of data was used across models • Relative size of errors important Natural Resource Consultants Since 1921

Measured vs. Predicted Average Growth • High level view of growth • PAI • Focus on four youngest age classes due to sample size Natural Resource Consultants Since 1921

Measured vs. Predicted Average Growth Natural Resource Consultants Since 1921

Measured vs. Predicted Average Growth • Performance? – SIS, PN, FPS, NWO all about same so far – SMC not as good – WC least accurate so far Natural Resource Consultants Since 1921

Basic Error Stats - Stands • Errors: Predicted - Observed – Negative = under-prediction – Positive = over-prediction • Errors not annualized** • Stand-level and Tree-level • FPS – no grown treelist output Natural Resource Consultants Since 1921

Basic Error Stats - Stands SIS TPA FPS FVSPN FVSWC O-SMC O-NWO -3. 5 6. 8 10. 6 7. 1 22. 3 19. 5 20. 7 21. 5 19. 4 20. 3 2. 325 2. 035 2. 159 2. 242 2. 026 2. 112 Mean -1. 6 -1. 1 3. 6 -21. 3 -8. 5 -4. 5 Std. Dev 17. 4 15. 3 26. 5 14. 3 15. 3 13. 8 Std. Error 1. 809 1. 598 2. 758 1. 491 1. 596 1. 434 Mean -0. 1 -0. 4 0. 3 -0. 9 -0. 6 -0. 4 Std. Dev 0. 71 0. 52 0. 91 0. 57 0. 46 0. 47 Std. Error 0. 074 0. 054 0. 095 0. 059 0. 048 0. 049 Mean -1. 7 na -2. 1 -8. 5 -2. 8 -2. 6 Std. Dev 4. 2 na 3. 9 4. 8 3. 7 3. 9 0. 438 na 0. 410 0. 500 0. 381 0. 402 Mean -1, 426 -3, 289 -1, 581 -6, 489 -2, 596 -1, 811 Std. Dev 3, 397 3, 425 4, 233 4, 008 2, 925 2, 557 Std. Error HT 40 (feet) 8. 8 Std. Error QMD (inches) 2. 3 Std. Dev BA (ft 2/ac) Mean 354. 1 357. 1 441. 3 417. 9 305. 0 266. 6 Std. Error BFVOL (Bdft/ac) Natural Resource Consultants Since 1921

Basic Error Stats - Stands Natural Resource Consultants Since 1921

Basic Error Stats - Trees SIS FPS FVSPN FVSWC O-SMC O-NWO Mean NA 0. 7 -0. 5 -0. 4 -0. 2 SD 0. 9 NA 1. 0 0. 9 0. 8 0. 7 0. 014 NA 0. 017 0. 015 0. 014 0. 012 -0. 6 NA -1. 2 -6. 5 -2. 4 -2. 5 6. 6 NA 7. 5 8. 0 6. 6 6. 5 0. 107 NA 0. 123 0. 130 0. 107 0. 106 Mean DBH 0. 1 -8. 5 NA 2. 6 -32. 3 -18. 6 -12. 1 SD 38. 8 NA 36. 0 48. 9 37. 3 32. 4 0. 675 NA 0. 626 0. 849 0. 649 0. 562 Std Err Mean HEIGHT SD Std Err BFVOL Std Err Natural Resource Consultants Since 1921

Basic Error Stats - Trees Natural Resource Consultants Since 1921

Basic Error Stats • Performance? – SIS smallest mean errors for all but BA (2 nd smallest) and average variability – PN probably second best choice – NWO was least variable – SMC and WC falling out of the race Natural Resource Consultants Since 1921

Error CDF’s - Stand • Cumulative Distribution Functions • Picture of error distribution by error size • More information than a mean bias Natural Resource Consultants Since 1921

Error CDF’s - Stand Natural Resource Consultants Since 1921

Error CDF’s - Tree Natural Resource Consultants Since 1921

Error CDF’s - Tree • Performance? – NWO and SIS had largest % of small errors – FPS and SMC next best, with PN close behind – WC doesn’t seem to be a good fit Natural Resource Consultants Since 1921

Significance Tests • Paired t-test vs. Wilcoxon signed rank test – All data – 5 -7 yr vs. 8 -10 yr Projections – Initial Vol <= 25 MBF vs. Initial Vol > 25 MBF – Unthinned vs. Thinned Natural Resource Consultants Since 1921

Significance Tests p-values FPS FVSPN FVSWC O-SMC O-NWO All 0. 2459 0. 9503 0. 0278 0. 1497 0. 6656 0. 2015 5 -7 yr Projections 0. 8441 0. 0529 0. 0077 0. 3755 0. 5902 0. 3088 8 -10 yr Projections 0. 0000 0. 0001 0. 0000 Initial Vol < 25 MBF 0. 0000 0. 0506 0. 0188 0. 0050 0. 0479 0. 0188 Initial Vol > 25 MBF 0. 0187 0. 0061 0. 4675 0. 3694 0. 0293 0. 3786 Un. Thinned 0. 5254 0. 5550 0. 1208 0. 2195 0. 8675 0. 2408 Thinned TPA SIS 0. 1981 0. 2209 0. 0480 0. 5509 0. 1981 0. 5936 Natural Resource Consultants Since 1921

Significance Tests p-values FPS FVSPN FVSWC O-SMC O-NWO All 0. 1610 0. 0398 0. 0273 0. 0000 0. 0023 5 -7 yr Projections 0. 0266 0. 1347 0. 0023 0. 0000 0. 0049 0. 0686 8 -10 yr Projections 0. 0000 0. 0557 Initial Vol < 25 MBF 0. 5641 0. 4096 0. 3630 0. 0000 0. 0718 0. 0067 Initial Vol > 25 MBF 0. 1099 0. 0673 0. 0523 0. 0001 0. 0053 0. 1687 Un. Thinned 0. 6885 0. 4298 0. 1894 0. 0000 0. 3277 0. 0105 Thinned BA SIS 0. 0157 0. 0029 0. 0008 0. 0000 0. 0157 0. 6832 Natural Resource Consultants Since 1921

Significance Tests p-values FPS FVSPN FVSWC O-SMC O-NWO All 0. 0525 0. 0001 0. 5513 0. 0000 5 -7 yr Projections 0. 5668 0. 2485 0. 8441 0. 0000 0. 0006 8 -10 yr Projections 0. 0000 Initial Vol < 25 MBF 0. 8861 0. 0107 0. 1361 0. 0000 0. 0073 Initial Vol > 25 MBF 0. 0006 0. 0001 0. 0858 0. 0000 Un. Thinned 0. 2140 0. 0013 0. 3793 0. 0000 Thinned QMD SIS 0. 0843 0. 0157 0. 3967 0. 0010 0. 0029 Natural Resource Consultants Since 1921

Significance Tests p-values FPS FVSPN FVSWC O-SMC O-NWO All 0. 0002 NA 0. 0000 5 -7 yr Projections 0. 9659 NA 0. 4780 0. 0000 0. 2089 0. 2701 8 -10 yr Projections 0. 0029 NA 0. 0001 0. 0000 Init Vol < 25 MBF 0. 0049 NA 0. 0002 0. 0000 0. 0105 Init Vol > 25 MBF 0. 4780 NA 0. 1486 0. 0000 0. 0010 0. 0008 Un. Thinned 0. 0008 NA 0. 0000 Thinned Height SIS 0. 6378 NA 0. 7299 0. 0003 0. 7299 0. 8261 Natural Resource Consultants Since 1921

Significance Tests p-values FPS FVSPN FVSWC O-SMC O-NWO All 0. 0987 0. 0000 0. 0005 0. 0000 5 -7 yr Projections 0. 5214 0. 0005 0. 0019 0. 0000 8 -10 yr Projections 0. 0154 0. 0000 0. 0200 0. 0000 Initial Vol < 25 MBF 0. 9414 0. 0000 0. 7521 0. 0000 0. 0184 Initial Vol > 25 MBF 0. 0000 0. 0544 0. 0004 Un. Thinned 0. 3767 0. 0000 0. 0065 0. 0000 Thinned BD FT VOL SIS 0. 0157 0. 0010 0. 0132 0. 0000 0. 0132 0. 0076 Natural Resource Consultants Since 1921

Significance Tests • Performance so far? – Shorter projections generally better (higher p-values) – Less significance in higher volume stands than lower – Thinned vs. unthinned unclear – SIS and PN least significant differences, followed by NWO Natural Resource Consultants Since 1921

Simple Linear Regression • Oi = β 0 + β 1*Pi + εi • Nature of the bias if it is present, telling us whether it is constant or changing and to what degree. Natural Resource Consultants Since 1921

SLR Results TPA Model SIS FPS FVS-PN FVS-WC O-SMC O-NWO Parameter BA QMD Value Sig Value 7. 45 No 21. 98 Yes 1. 53 Slope 0. 9763 No 0. 8852 Yes Intercept 12. 18 Yes 5. 08 Slope 0. 9844 No 6. 39 HT Value Sig Value Yes 0. 94 No 1999. 39 Yes 0. 8779 Yes 0. 9745 No 0. 8902 Yes No 0. 46 Yes ------ 926. 49 No 0. 9698 No 0. 9404 Yes ------ 0. 8649 Yes No 79. 12 Yes 2. 74 Yes 1. 56 No 4830. 75 Yes 0. 9545 No 0. 6326 Yes 0. 8221 Yes 0. 9646 Yes 0. 7945 Yes 6. 87 No 7. 32 No 0. 22 No -11. 43 Yes -571. 86 No Slope 0. 9995 No 0. 8607 Yes 0. 9164 Yes 1. 0281 No 0. 8103 Yes Intercept 13. 86 Yes 3. 87 No 0. 18 No -1. 99 No -348. 21 No Slope 0. 9849 No 0. 9397 Yes 0. 9401 Yes 0. 9923 No 0. 9280 Yes Intercept 11. 02 Yes -0. 42 No -0. 01 No -0. 96 No -395. 82 No Slope 0. 9821 No 0. 9801 No 0. 9703 No 0. 9837 No 0. 9546 Yes Intercept Slope Intercept Significance at α = 0. 05 Natural Resource Consultants Since 1921 Sig BFVol Sig

SLR Results • Performance so far? – NWO did best, especially when recall low variability – FPS and SMC the next best – SIS and PN several significant slopes and intercepts Natural Resource Consultants Since 1921

Long-Term Projections • Long-term remeasurement data uncommon • Grow young stands and plot against older inventory data • Less for identifying a ‘best’ so much as pointing out models to avoid Natural Resource Consultants Since 1921

Long-Term Projections Natural Resource Consultants Since 1921

Long-Term Projections • Performance so far? – NWO, SMC, FPS all reasonable in long-term predictions – PN and SMC saw affect of Max BA limit – SIS main point of concern for longterm predictions Natural Resource Consultants Since 1921

Overall Performance • No Clear Winner – Basic stats and significance tests point to SIS – CDF’s and regressions point to NWO – Overall, SIS, PN, and NWO comparable – FPS not far behind – SMC and WC lower performance Natural Resource Consultants Since 1921

Questions? Natural Resource Consultants Since 1921

Remeasurement Issues Issue No Initial Height No Final DBH Number Of Trees Types of Cruiser Comments 28 unable to get height 9 heavy leaner, unable to measure No Final Height 28 top bent, leaner, broken top Shrinking DBH 17 Shrinking Height 150 broken top Died 373 Grand Total 605 Natural Resource Consultants Since 1921