Estimation of Genetic Multipliers for
Douglas-Fir Height- and DiameterGrowth Models
Peter J. Gould, David D. Marshall, Randy Johnson and
Greg Johnson
Study Objectives
1. Estimate growth differences between
average (wood’s-run) tree and individual
families in terms of genetic-gain
multipliers.
2. Relate multipliers to breeding value
(BV = percent gain at age 10).
3. Evaluate multipliers effects in model.
Effect of Multipliers
25
Initial Size Advantage
Diameter (in)
Gain Multiplier= 0.05
20
Typical Tree
15
10
5
0
0
20
40
60
Year
80
100
NWTIC 1st-Generation Progeny Tests
Coop: breeding zone. Completely
independent families.
Sites: Geographical locations within
coops.
SET 1
SET 2
SET 3
Rep 1 Rep 2
Rep 1 Rep 2
Rep 1 Rep 2
Rep 3 Rep 4
Rep 3 Rep 4
Rep 3 Rep 4
DBH Data: Variation between Coops
10-YR GROWTH PERIOD
DBH Data: Variation between Sites
10-YR GROWTH PERIOD
DBH Data: Variation between Sets
10-YR GROWTH PERIOD
DBH Data: Breeding Values
BV = Age 10 Gain 1 (percent)
Modeling Strategy: Assumptions
1. Average growth = wood’s run.
2. Multipliers work with any
unbiased growth model.
3. Removing sources of variation
other than genetics is very
important.
Strategy:
1. Fit models with random effects at
site-set level.
2. Calculate genetic multiplier (m) for
each family at coop level.
Obs = m ∙ Pred
3. Estimate m from BV.
m = A0 + A1 ∙ BV
10-YR Modeling Dataset: HT Model
>16 coops
> 109 sites
> 513 site-sets
> 2485 families
> 222 818 observations
HT Model 1
∆HT = b1∙HTb2∙b3HT
random effects on b1,b2,b3
Fixed Effects:
∆HT = 231.7∙HT0.94∙0.86HT
HT Model 1
Model
R2
Base
37.6
Base + random effect
69.0
Residual Variation (%)
31.0
Between Families (%)
2.4
HT Model Results: Family M
Modeling Datasets: DBH Model
>7 coops
> 45 sites
> 193 site-sets
> 1160 families
> 76 012 observations
DBH Model 1
∆DBH = b1∙DBHb2∙b3DBH∙b4BA REP
random effects on b1,b2,b3
Fixed Effects:
∆DBH = 3.7∙DBH0.3∙1.01DBH∙0.97BA REP
DBH Model 1
Model
R2
Base
25.5
Base + random effect
61.6
Residual Variation (%)
38.4
Between Families (%)
3.3
DBH Model Results: Family M
10-yr A1 estimates:
Study
Ht
Diameter
Gould
0.001434
0.001577
Marshall
0.001498
0.001657
--
R. Johnson
0.001145
--
0.001824
0?
(BV = 13%)
G. Johnson
(assume BV=13%)
Other Periods
• Ht data for 5-yr (167,000 obs) and
15-yr (7600 obs) growth.
• DBH data for 5-yr (7,700 obs) and
15-yr growth (20,000).
• Estimates of m are higher for 5-yr,
but about the same for 15-yr growth.
What’s Next?
• Manuscript on multipliers.
• ORGANON interface.
• Test multipliers.