Developing a whole stand model for douglas fir plantations
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Developing a Whole-stand Model for Douglas-fir Plantations. Eric C. Turnblom Samuel D. Pittman. Whole-stand Model – Topics. Introduction Model Development Biological / Model Theory Equations / Data / Fitting Fit Assessment / Model evaluation Model Uses & Future Work Conclusion.

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Developing a whole stand model for douglas fir plantations

Developing a Whole-stand Model for Douglas-fir Plantations

Eric C. Turnblom

Samuel D. Pittman

Western Mensurationists Meeting


Whole stand model topics
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


Introduction
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


Introduction1
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


Stand management cooperative
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


Stand management cooperative1
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


Stand management cooperative2
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

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Stand management cooperative3
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


Stand management cooperative4
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


Stand management cooperative5
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


Introduction2
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


Whole stand model for douglas fir
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


Model development
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


Biological theory
Biological Theory

  • Maximum (limiting) size – density relationship

(Xue, et al. 1999)

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Biological theory1
Biological Theory

  • Every stand has a unique self-thinning boundary line driven by its unique stand allometry

(Turnblom & Burk 2000)

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Biological theory2
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


Model theory
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

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Model equations
Model Equations

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Model fitting data
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

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Model fitting parameterization
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

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Fit evaluation
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)

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Fit evaluation1
Fit Evaluation

  • Residual plotting

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Fit evaluation2
Fit Evaluation

  • Residual plotting

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Model evaluation
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

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Model evaluation1
Model Evaluation

  • Biological behavior

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Model evaluation2
Model Evaluation

  • Biological behavior

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Model evaluation3
Model Evaluation

  • Biological behavior

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Model evaluation4
Model Evaluation

  • Trajectory behavior

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Whole stand model for douglas fir1
Whole-stand Model for Douglas-fir

  • Model Uses & Future Work

  • Conclusion

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Model uses future work
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.)

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TreeLab (v1.0)

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TreeLab (v1.0)

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Site productivity modeling
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


Conclusion
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


Conclusion1
… Conclusion

  • Please visit <http:://www.standmgt.org/>

  • To download, click on the TREELAB link (LHS)

  • Eric C. Turnblom <[email protected]>

Western Mensurationists Meeting


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