Estimation and Application of GeneticGain Multipliers for DouglasFir Height and Diameter Growth

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Estimation and Application of Genetic-Gain
Multipliers for Douglas-Fir Height and Diameter
Growth

• Peter J. Gould1, David D. Marshall2,
• Randy Johnson1 and Greg Johnson2
• 1USDA Forest Service Pacific Northwest Research
  Station
• 2Weyerhaeuser Co.

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Outline

• Issues, concepts, objectives
• Data and modeling approach
• Results
• Applications for projecting yield

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Why Model Genetic Gain?

• Improved Douglas-fir is a reality in the PNW.
• Insight into stand development and return on
  investment (without waiting 20 yrs).
• Genetics studies have not focused on stand-level
  growth and yield.

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Genetic-Gain Multipliers
Predicted growth with genetic-gain
Predicted growth from woods-run model

• Example ?DG M ?DWR
• Extrapolates information from genetics studies
  to existing growth models.
• Other approaches include refitting equations and
  SI adjustments.

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Genetics Studies Questions Asked

• Geneticist What is the total height and diameter
  of a genotype at a given age relative to
  woods-run?
• Single-tree plots
• Families tested on multiple sites interested in
  mean across sites.
• Select best parents for seed orchards / breeding

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Genetics Studies Questions Asked

• Modeler What is the rate of height and diameter
  growth of an individual tree for a given period
  based on its pedigree and site, stand, and tree
  characteristics?
• Interested in growth within a stand.
• Genetics is one of many factors controlling
  growth.

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Concepts from Genetics

• Breeding value the value of a parent for
  passing some trait to its progeny (estimated from
  progeny tests).
• Genetic worth the expected level of gain for
  some trait of an improved seedlot.
• GW f(BVorchard, outside pollen)
• Both expressed as percentage difference from
  population (woods-run) mean in traits such as
  total height and diameter at a given age.

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NWTIC 1st Generation Progeny Tests

• Seed collected from wild, woods-run parents to
  test half-sib families.
• BV calculated for mother trees at age 10 yrs
  (genetics perspective).
• We used same data (up to age 20 yrs). Half-sib
  families treated as individual seedlots where

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Study Objectives

• Estimate genetic-gain multipliers for height and
  diameter growth for improved DF seedlots when GW
  is known.
• M f (GW, stand age)
• Evaluate multiplier effects in growth models
  (ORGANON and FVS).

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Modeling Strategy

• 1. Estimate growth of individual trees (e.g.,
  ?DWR) in progeny tests using woods-run models.
• 2. Calculate seedlot-level multipliers (M) from
  observed growth and expected growth under the
  woods-run model.
• ?DG M ?DWR
• M ?DG / ?DWR
• 3. Estimate M from seedlots GW.

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NWTIC 1st Generation Progeny Tests
Breeding zone area of relatively uniform
environment ( 50,000 ha) Site Geographical
location within breeding zone.Set Group of
families tested together. A more-or-less random
sample of woods-run population.
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DBH Data Variation Between Breeding Zones
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DBH Data Variation Between Sites
10 to 15 yr DBH Increment (cm)
10-yr DBH (cm)
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DBH Data Variation Between Sets
10 to 15 yr DBH Increment (cm)
10-yr DBH (cm)
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Challenges of Progeny Test Data

• Limited individual-tree measurements
• No crown ratios or crown class
• Single-tree plots
• No stand density (e.g., basal area)
• No site index
• Mixed genotypes
• Superior trees may perform better
• Inferior trees may perform worse

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Modeling Strategy

• Could not use an existing model
• Unmeasured variables
• Precision needed to estimate small effects
• Created custom woods-run models
• Ex ?HT b1HTb2b3HT
• random effects on b1,b2,b3 at set level
• Separate models fit for 5- 10-, and 15-yr
  periods.

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Mixed Genotypes

• Probably not very important
• much overlap between seedlots in size /
  competitive position.
• Woods-run models account for differences in
  initial size.

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NWTIC 1st Generation Progeny Tests
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Woods-run Model Height Growth
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Woods-run Model Height Growth
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Woods-run Model Height Growth
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Woods-run Model Height Growth
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Estimating Height-Growth Multipliers

• M a0 a1 GW
• OLS, WLS and method-of-moments regression fits
  (error in GW).
• WLS fits
• Period Equation
  
• 5 1 0.006277GW
• 10 1 0.003112GW
• 15 1 0.004474GW

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Estimating Diameter-Growth Multipliers

• WLS fits
• Period Equation
  
• 5 1 0.010105GW
• 10 1 0.003370GW
• 15 1 0.002944GW

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We Have Multipliers Now What?

• ORGANON (Mark Hanus and David Hann).
• FVS PN and WC (FIXHTG and FIXDG keywords).
• Tested virtual seedlot with 10 GW for height
  and diameter at 10 yrs.

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We Have Multipliers Now What?

• Tree list for 10-yr-old stands generated with
  FGROW (Flewelling and Marshall).
• Adjusted 10-yr height and diameters by
  multiplying by 1.10.
• Tested adjusted tree list with and without
  genetic-gain multipliers.

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Projections
Woods-Run Volume (cuft)
Gain with Treelist (cuft)
Gain with Multipliers (cuft)
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Projections 40-yr Rotation
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Projections 60-yr Rotation
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Conclusions

• Multipliers can put genetic information in
  models right now, though many questions remain.
• Genetic effects are relatively small, but
  significant.
• Modelers need more information and more precise
  estimates than tree breeding programs.
• Operational and controlled experiments are
  needed.