Effect of Site, Age, and Treatments of Type II Installations on Standing Tree Acoustic Velocity

1. Effect of Site, Age, and Treatments of Type II Installations on Standing Tree Acoustic Velocity David Briggs, Eric Turnblom, Gonzalo Thienel File: Agenda_2020_TreeLogMill_Study Plan_Mar_6_06.ppt Date: May 24, 2007

2. Introduction

3. Study Background: AGENDA 2020 Project “Non-destructive evaluation of wood quality in standing Douglas-fir trees and logs” David Briggs[1], Eini Lowell[2], Eric Turnblom[1], Bruce Lippke[3], Peter Carter[4] [1] Stand Management Cooperative (SMC) University of Washington, Seattle, WA [2] USFS PNW Research Station, Portland, OR [3] Rural Technology Initiative (RTI), University of Washington, Seattle, WA [4] Manager Resource Technology & Commercialization, CHH Fibre-Gen, New Zealand Issue: Lack of information may lead to use of cultural treatments with detrimental effects on future wood quality and product value. New field tools are now available that allow rapid non-destructive assessment of one measure of wood quality (stiffness) in standing trees and logs.

4. Objective 1 : • Evaluate stiffness along the tree to product chain to • Define relationships between stiffness of lumber or veneer within a log, the stiffness of the log, and the stiffness of the parent tree • Assess the effect of treatment and stand variables on these relationships

5. Study Cooperators University of Washington College of Forest Resources USDA Forest Service, PNW Research Station USDA Forest Service, Forest Products Laboratory CHH Fibre-Gen, New Zealand Green Diamond Resource Company Port Blakely Tree Farms WA State Department of Natural Resources Weyerhaeuser Company

6. This Presentation • Analysis of standing tree data from Douglas-fir • Collected in September 2006

7. Objective : What are the influences of thinning regimes, stand age, DBH, stems per acre, and site class on the acoustic time of flight (SWT) in stand Douglas-fir trees? • Note: velocity (m/sec) and time-of-flight (stress-wave-time, SWT) (sec/m) are reciprocals

8. Previous studies : • Thinning effect • lower acoustic velocity in Sitka Spruce (citation reference) • higher acoustic velocity in Douglas-fir (citation reference) • DBH effect • Within a given stand there is a weak negative relation between acoustic velocity and dbh (therefore a weak positive relation between SWT and dbh) • No information on effects of site • Expect an effect of age (trees add denser, stiffer mature wood as they age)

9. Sample Stands : SMC Type II Installations

10. Stress-wave-time (SWT) of standing trees • 4 installations x 5 plots = 20 plots • One plot at one installation not usable  prior wind damage • 52 trees in a stem-mapped circular plot • TreeSonic time-of-flight μsec (SWT) over 1 m distance • 3 readings at each location • 3 equidistant locations on circumference of each tree

11. Results • Within-installation • Treatment plot differences • Trends with dbh within treatment plots

12. Within Installation Treatment Plot Differences • Ho: The average SWT within the plots in a particular installation are all the same. µ1 = µ2 = µ3 = µ4 = µ5 • Ha: At least there is one inequality in the average SWT between the plots in a particular installation.

13. One-Way ANOVA We reject null hypothesis at α = 0.95

14. SWT vs. Stems/Acre • Are differences due to chain-saw effect of thinning or due to the growth response after thinning? 4 5 3 4 2 1 3 2 1 2 5 1 3 5 4 1 3 2 5

15. SWT vs DBH by Installation In general increased SWT is weakly associated with increased DBH; hence velocity (stiffness) is weakly decreasing with increased dbh as others have found

16. SWT vs DBH by Installation However, younger installations seem to have more variability. Why?

17. Results • Between-installations • Site index (King) • Stand Age

18. STAND AGE SITE INDEX (King) • Older stands have lower SWT  higher velocity  higher stiffness • SI is that given by landowner when established; may be poor reflection of current stand 805 805 807 807 808 808 803 803

19. Next Steps

20. Next Steps • Find the source (s) of variation in SWT within and between plots (Thinning regimes ???) • Get better estimates of site index • A general model  SWT = f(age, site index, stocking/thinning level) • Switch to the 12 trees harvested from each plot • Relationships between acoustic (TreeSonic) of standing tree and its merchantable bole (HM-200), woods logs, and mill-length logs • Include wood density. Cookies from each end of every log • Include knot data. • Relation between TreeSonic and ST-300 • Include results of veneer & lumber tests

21. References • Briggs, D.G. and W.R. Smith. 1986. Effects of Silvicultural Practices on Wood Properties--A Review. In: Douglas-fir: Stand Management for the Future. Oliver, C.D., D.P. Hanley, and J.A. Johnson, eds., June 18-20, 1985. College of Forest Resources, University of Washington, Seattle, WA. Contrib. No. 55. pp. 108-117. • Carter, P. D. Briggs, R.J. Ross, X. Wang 2005. Acoustic Testing to Enhance Western Forest Values and Meet Customer Wood Quality Needs. In Harrington Constance A., Schoenholz, Stephen H. eds.; “Productivity of Western Forests: A Forest Products Focus” Gen. Tech. Rep. PNW-GTR-642; U. S. Department of Agriculture, Forest Service Pacific Northwest Research Station, Portland OR. pp 121-129. • Wang, X., R.J. Ross, M. McClellan, R.J. Barbour, J.R. Erickson, J. W. Forsman, G.D. McGinnis. 2001. Nondestructive Evaluation of Standing Trees with a Stress Wave Method. Wood & Fiber Science 33(4): 522-533.