Modeling Branch Characteristics In Douglas-fir & Western Hemlock

1. Modeling Branch Characteristics In Douglas-fir & Western Hemlock

2. Cast of Characters • Dr. Gero Becker • Professor, Univ. of Freiburg, Germany, Visiting Scholar, SMC • Dr. David Briggs • Professor UW CFR, Director, SMC • Dr. Olav Hoibo • Associate Professor, Agric. Univ. Norway, Visiting Scholar, SMC • Eric Turnblom • Assistant Professor, UW CFR, Silviculture Project Leader, SMC

3. Branches Respond Too!

4. Outline • Number & Diameter of BH Branches: SMC Protocol • Type I Douglas-fir: PCT Effect on Average BH Branches in a Stand • Type I Douglas-fir: PCT Effect on BH Branches of Individual Trees • Type I Western Hemlock: PCT Effect, status • Type III: Effect of Initial Spacing, status • PNW/Germany Cross-Comparison of DF Branch Diameter • Vertical Branch Profiles: DF & WH • Live/dead transition • Branch/Stem Growth Dynamic

5. I. Number & Diameter of BH Branches • Douglas-fir branch protocol • Type I and Type III Installations • Taken on height trees on each plot (~42 trees) • First whorl above BH • Diameter of largest branch in the whorl • Total # branches in whorl >= 1/2 diameter of largest branch • Total # branches in half-internode above & below the whorl that are >= 1/2 diameter of largest whorl branch

6. A. Effect of PCT on Douglas-fir: Stand Level Models • Sample • 19 Type I installations • 57 plots ISPA, ISPA/2, ISPA/4 • 2397 trees • Site Index is Flewelling (2001)

7. A. Effect of PCT on Douglas-fir: Stand Level Modeling Method • Factorial Treatment Structure • 4 levels of Flewelling Site Index • 3 levels of stand density (stems/acre) • Covariates: • Crown length, crown ratio • Mean height, HT_40, mean height above BH • Total age, BH age • QMD, relative density • Plots with crown base < BH, > BH, and combined • No differences found with crown base below vs above BH • Elapsed time since crown receded above BH is too short

8. 1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results • as stems per acre increases total BH branch count decreases • more shade on BH branches in denser stands • 250 & 550 spa classes are not significantly different • 125 spa class is significantly different

9. 1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results • Site classes I, II, & III are not significantly different • Site IV is significantly lower • fewer resources to produce and maintain branches • Also, total BH branch count • Decreases as average crown length of stand increases (more shade on BH branches ?) • Decreases as total stand age increases (self pruning?)

10. 2. Effect of PCT on BH Nodal Branch Count of Type I Douglas-fir Stands: Results • Site classes II & III are not significantly different • Site classes II & IV are not significantly different • Highest site class has about 1 more nodal branch (more resources for nodal branch production & survival?)

11. 3. Effect of PCT on BH Internodal Branch Count of Type I Douglas-fir Stands: Results • Site classes II, & III are not significantly different • Site III, I, & IV are not significantly different • Site IV low due to fewer resources for production & survival of internodal branches • Site I low due to competition and shading by more numerous nodal branches • Also, BH internodal branch count • Decreases as average crown length of stand increases (more shade on BH internodal branches ?) • Decreases as total stand age increases (self pruning of internodals?)

12. 4. Effect of PCT on BH Branch Count of Type I Douglas-fir Stands: Regression Models Total = f (ave crown length, stems/acre, total age, site index) Internodal = f (ave crown length, total age, site index) Nodal = Total - Internodal

13. 5. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Models • All significantly different • Lower stand density has larger BH branches (more space, less shade on BH, longer lived faster growing branches) • Also, largest BH branch diameter • Increases as QMD increases (bigger tree allometry?) • Decreases as total stand age increases (point of maximum branch diameter becomes embedded inside the stem

14. 6. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Model Average for Stand = f(QMD, total age, stems per acre)

15. B. Effect of PCT on Douglas-fir: Individual Tree Modeling Method • Allometry with orthogonal quadratic polynomials for each of the 57 plots • Largest BH branch diameter vs other tree size measures: DBH best • Branch counts vs other tree size measures: DBH best • ANCOVA of 57 sets of coefficients • 4 levels of Flewelling Site Index • 3 levels of stand density (stems/acre) • Covariates: • Crown length, crown ratio • Mean height, HT_40, mean height above BH • Total age, BH age • QMD, relative density • Plots with crown base < BH, > BH, and combined • No differences found with crown base below vs above BH • Elapsed time since crown receded above BH is too short • Regression

16. 1. Effect of PCT on BH Branch Counts of Douglas-fir Trees: Regression Model Total =f(DBH, stems per acre, total age, site index, crown length) Internodal: use stand level model = f(total age, site index, crown length) Nodal = Total - Internodal

17. 2. Effect of PCT on Largest BH Branch Diameter of Douglas-fir Trees: Regression Model Individual Tree Largest BH Branch Diameter = f(DBH; stems per acre, total age, QMD, crown length)

18. 3. Conclusion: PCT of Douglas fir (Type I) • Stand level variables (red) greatly improved individual tree model predictions! • O. Hoibo has also found this in his crown profile research • Status: • Article in review with Forest Science • Future • Can we relate the BH results to the rest of the tree • Can we develop a QC tool & prediction system that can be related to log grades/sorts

19. C. Effect of PCT & Planting Density: W. Hemlock Protocol & Plans • Type I and Type III Installations • Taken on height trees on each plot (~42 trees) • 3 foot zone centered on BH • Diameter of largest branch • Total # branches >= 1/2 diameter of largest branch • Started in 00/01 Field Season • Preliminary analysis after 01/02 season 3 ft

20. D. Effect of Planting Density: Douglas-fir • Type III • Data for 98/99, 99/00, 00/01, 01/02 seasons • Preliminary work with 98/99 data • 8 installations; 6 plots each • small trees on wider spacings tend to have larger branches than same age, larger trees on denser spacings • another aspect of crossover effect? • Will begin analysis this winter/spring

21. II. PNW/Germany Cross-Comparison of DF Branch Diameter Objectives: Determine differences between branch diameter profile characteristics between two geographically disparate (Germany/PNW U.S.) Douglas-fir data sets Gain insights into “best” modeling approach for future branch diameter modeling

22. Available Data • German data set • 4 plots: density ranges 150 -300 SPA; sites range 100 -140 ft@50 yr; total ages range 32 -41 years • 42 trees: DBH ranges 9.4 -16.1 in.; total heights range 62 -89 ft; HCB ranges 25.6 -47.6 ft. • SMC ‘Crown Study’ data set • 66 plots: density ranges 80 -600 SPA; sites range 80 -140 ft@50 yr; total ages range 9 -36 years • 562 trees: DBH ranges 1.0 -18.3 in.; total heights range 7.4 -104.7 ft; HCB ranges 0 -67.1 ft.

23. Testing Equations • Wobst/Becker Equation: • Maguire, et al. (1999) Equation:

24. Branch Diameter Profile Comparison • Upper curve (red) is Wobst/Becker model • Lower curve (maeve) is Maguire et al. • Upper is for live/dead branches, lower is for live only

25. Residual Patterns Wobst/Becker Maguire, et al.

26. Residuals Comparison On average, Maguire et al. predicts larger branches, but ...

27. Future Plans • Use both models to predict branch diameters on trees in the SMC data set • Determine which modeling approach / equation form is “best” • Report results at IUFRO conference 2002

28. III. Vertical Branch/Knot Profiles: DF • Douglas-fir Sample • SMC Type I • High Site, Medium Site • ISPA , ISPA/2 • Similar age & ISPA • 1 tree from each septile of DBH distribution (28 total trees) • 7 trees x 4 plots = 28 trees • Whorl 3, 6, 9, … 21 from top = 7 whorls/tree

29. A. Transition from Live to Dead Knot: DF • Branch Measurements • Azimuth • Horizontal distance from cambium to • Pith • Live/dead transition • Knot diameter at • Live/dead transition • Cambium • 1 branch diameter distance from stem surface (outside bark) • All branches • Data collected & analysis underway

30. B. Relationship Between Stem & Branch Diameter Growth • Measure • Smallest, median & largest of the 7 tree sample from each plot • Whorl # 6, 12, 18 from top • Annual ring widths of stem cross-section • Annual ring widths of smallest, median, & largest branch in each • Data collected & analysis underway

31. C. Vertical Branch/Knot Profiles: W. Hemlock • Sample • Medium Site Type I Hemlock • ISPA & ISPA/2 • 1 tree/septile of DBH distribution = 14 total trees • 3 foot sections @ mid-live crown, live crown base, midway from crown base to ground, and at BH • Transition from sound (live) to unsound (dead) knot • Sound knot length from pith • Knot diameter (max) at transition • Largest 5 and next to smallest branch = 6 total • Ring growth of stem & branch: all stem sections (4/tree) • Ring widths of stem • Ring widths of largest, median, & smallest branch • Samples collected: Anyone want a job?

32. The End