Developing a Whole-stand Model for Douglas-fir Plantations

1. Developing a Whole-stand Model for Douglas-fir Plantations Eric C. Turnblom Samuel D. Pittman Western Mensurationists Meeting

2. Whole-stand Model – Topics • Introduction • Model Development • Biological / Model Theory • Equations / Data / Fitting • Fit Assessment / Model evaluation • Model Uses & Future Work • Conclusion Western Mensurationists Meeting

3. Introduction • Stand Management Cooperative • Mission • To provide a continuing source of high-quality information on the long-term effects of silvicultural treatments and regimes on stand and tree growth and development and on wood and product quality Western Mensurationists Meeting

4. Introduction • Stand Management Cooperative • Objectives • To support modeling • Installations contain a wider range of treatments than current practice • To support managers • Provide timely information and guidance to those who are managing similar stands Western Mensurationists Meeting

5. Stand Management Cooperative • Membership • Companies: Boise Cascade, Longview Fiber, Port Blakely Tree Farms, West Fork Timber, etc. (15 in total) • Tribal Lands: Quinault Dept. Natural Resources • Federal Agencies: Bureau of Land Management • State & County Agencies: ODF, WA DNR, King Co. DNR • Institutions: BC Ministry Of Forests, FORINTEK Canada, USFS PNW Research Station • Universities: OSU, UBC, UW • Suppliers: Agrium UJS, Inc., JR Simplot Co., etc. Western Mensurationists Meeting

6. Stand Management Cooperative • Organization: • Policy Committee (chair, vice-chair) • Director • Projects, Field Crew, Database Management, Office Staff • Project (Technical Advisory Committees, or TAC’s) • Nutrition • Silviculture • Wood Quality • Modeling Western Mensurationists Meeting

7. Stand Management Cooperative • What’s measured • Tree and derived Stand Attributes • Live: Species, DBH, Height, height-to-crown base, crown width, damage • Dead: size & condition of snags until fallen • Branch Measurements (BH) • Largest Branch diameter, branch count (live & dead) • Understory Vegetation • Average foliage height, coverage (%) by species Western Mensurationists Meeting

8. Stand Management Cooperative • What’s Measured • Habitat Indicators • Depth of duff to mineral soil, FSD (%) • Site Characterization • Soil • 0 - 6”, 6 - 12” composited from five sample points per plot • Forest Floor • 1 sq. ft plots, four per measurement sample plot • Foliar Nutrients • Upper 1/3 of crown, 1 year after fertilization, 12 trees per plot Western Mensurationists Meeting

9. Stand Management Cooperative • History • Regional Forest Research Nutrition Project (RFNRP) • Commenced in 1969 (western WA, OR) • Stand Management Cooperative (SMC) • Formed 1985, 1st operational year 1986 • Western WA, OR, southwestern BC • In 1991, RFNRP rolled into SMC Nutrition Project Western Mensurationists Meeting

10. Stand Management Cooperative • Cohorts • RFNRP • Phase I : Unthinned natural stands, originating 1930’s • Phase II : Thinned natural stands, originating 1930’s • Phase III : Young thinned plantations, planted 1940’s • Phase IV : Precommercially thinned plantations; 1960’s • SMC • Type I : Variously treated plantations; 1970’s • Type II : Variously thinned plantations; 1950’s • Type III : Range of planting spacings; late 80’s - 90’s • Type IV : Range of planting spacings, genetics; 2K’s Western Mensurationists Meeting

11. Introduction … • Study & Modeling Objectives • Benchmark existing growth simulators • Summarize early growth & development of immature, managed stands of Douglas-fir • Investigate and understand the influence of stand structure on growth and yield • Produce variable-density growth and yield tables in user-friendly format Western Mensurationists Meeting

12. Whole-stand Model for Douglas-fir • Model Development • Biological / Model Theory • Equations / Data / Fitting • Fit Assessment / Model evaluation • Model Uses & Future Work • Conclusion Western Mensurationists Meeting

13. Model Development • Biological Theory • Growing space • As available space decreases, so does potential for growth • Allometric relationships • Relate growth in part of an organism to another part • Maximum (limiting) size - density relationships • Only so much biomass can be “packed” into available space Western Mensurationists Meeting

14. Biological Theory • Maximum (limiting) size – density relationship (Xue, et al. 1999) Western Mensurationists Meeting

15. Biological Theory • Every stand has a unique self-thinning boundary line driven by its unique stand allometry (Turnblom & Burk 2000) Western Mensurationists Meeting

16. Biological Theory • Stand allometry is dynamic, not static; allometric relationships change with stage of development • The rate at which a stand variable changes is found by differencing gross growth & respiration (anabolic & catabolic processes, respectively) • The magnitudes of the anabolic and catabolic processes depend on the current state of the stand and is affected by site quality Western Mensurationists Meeting

17. Model Theory • The current state of the stand can be described by the triplet (stand basal area, quadratic mean DBH, and dominant height) • Dynamic allometry is captured through simultaneous, coupled rate equations Western Mensurationists Meeting

18. Model Equations Western Mensurationists Meeting

19. Model Fitting Data • Untreated, pure DF (> 80% by BA) plots • Initial BHA averaged 14 years, ranging to 51 years • Site index from 85 to 145 ft @ 50 yrs BHA (King) • 459 plots total; 249 used in fitting, 210 for benchmarking • Measured every 4 yr, ranging 1 to 6, averaging 4.4 • Single plot measurements span 4 to 26 yrs Western Mensurationists Meeting

20. Model Fitting Parameterization • First order, centered differencing used to create a differential data set matching a yield data set constructed from mid-point of yield values • System of three equations was fit to the data using the objective function Western Mensurationists Meeting

21. Fit Evaluation • Residual graphs were examined • Visual quality of predicted trajectories were assessed for agreement with known biological behaviors • Attempts were made to augment the system of equations with other system state variables (e.g. stand form) Western Mensurationists Meeting

22. Fit Evaluation • Residual plotting Western Mensurationists Meeting

23. Fit Evaluation • Residual plotting Western Mensurationists Meeting

24. Model Evaluation • Results - biological behavior • Growth & yield dynamics on two sites • High site (dashed): SI= 145 • Low site (solid): SI= 85 • Otherwise similar in Q, B, H, Age Western Mensurationists Meeting

25. Model Evaluation • Biological behavior Western Mensurationists Meeting

26. Model Evaluation • Biological behavior Western Mensurationists Meeting

27. Model Evaluation • Biological behavior Western Mensurationists Meeting

28. Model Evaluation • Trajectory behavior Western Mensurationists Meeting

29. Whole-stand Model for Douglas-fir • Model Uses & Future Work • Conclusion Western Mensurationists Meeting

30. Model Uses & Future Work • Boundary conditions to individual-based or tree-list models • TreeLab (v1.0) • Variable-density yield simulator for immature, managed Douglas-fir plantations • Site productivity evaluation & modeling in management-oriented and process-based growth model hybrids (proposal to USFS / AFPA collab.) Western Mensurationists Meeting

31. TreeLab (v1.0) Western Mensurationists Meeting

32. TreeLab (v1.0) Western Mensurationists Meeting

33. Site productivity modeling • This proposed research seeks to: • Better understand mechanisms driving forest growth & productivity in young DF stands • Examine & interpret association between environmental & HydroGeoMorphic attributes of a site / stand and parameters of the TreeLab whole-stand model • High potential to derive a site-characterization parameter to augment site index Western Mensurationists Meeting

34. Conclusion … • Whole-stand Model propositions • Unique self-thinning boundary for each stand • Stand allometry is dynamic, not static • Changes in stand attributes are represented as a coupled system of rate equations that govern allometry • Whole-stand model with the most plantation data • Young data set (for stand development) • Based on assumed maximums (BA, QMD and Htop) Western Mensurationists Meeting

35. … Conclusion • Please visit <http:://www.standmgt.org/> • To download, click on the TREELAB link (LHS) • Eric C. Turnblom <ect@u.washington.edu> Western Mensurationists Meeting