Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007 1 Looking for the Plateau in...
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Transcript of Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007 1 Looking for the Plateau in...
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
1
Looking for the Plateau in Douglas-fir Annual Volume Increment
David M. Hyink, Ph.D. (retired)
Timberlands & Raw Materials R & D
Weyerhaeuser Company
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Outline/Topics
Context and Rationale for Growth and Yield Research Biological First Principles
• “Laws” of Self-Thinning
• Langsaeter’s Hypothesis Weyerhaeuser’s Langsaeter Study
• Design
• Results & Conclusions Questions/Comments
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Forest Growth & Yield and Wood QualityWhat do we want to know?
How stand management options…• Species, genotype, site preparation, planting spacing, non-crop competition &
animal control, thinning, fertilization, pruning
Produce key properties of crop trees…• Dbh, height, crown ratio, stem form, branches & knots, specific gravity, micro-
fibril angle, earlywood/latewood
That create value for specific end-uses.• Logs, lumber, fiber, engineered components
“Engineering-on-the-Stump”
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Forest Growth & Yield and Wood QualityScientific Approach – Data and models
Based upon “First Principles”• Dominant Height / Age / Site Index• Landform / Habitat Type• “Laws” of Self-Thinning (Reineke, Drew and
Flewelling)• Growth vs. Growing Stock Relationships
(Langsaeter)
Continuously updated as new data and experimental results become available.
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Biological First Principles / Langsaeter’s Hypothesis
The total production of cubic volume by a stand of a given age and composition on a given site is, … constant and optimum for a wide range of density of stocking. It can be decreased, but not increased, by altering the amount of growing stock to levels outside this range.
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Biological First Principles / “Laws” of Self-Thinning
Reineke Stand Density Index Relative Density Index Reineke (1933) Drew and Flewelling (1979)
0.15
0.55
0.55
0.15
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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The Langsaeter Study
Superimposed on an existing DF research plantation (SI=143) Initial planting spacing: 5’x5’ (1742) and 8’x8’ (680) 4 reps of 4 treatments at each initial spacing (32 plots):
• Non-thinned
• Maintain Relative Density (D&F) 0.25 – 0.35
• Maintain Relative Density (D&F) 0.40 – 0.50
• Achieve RD (D&F) 0.50, then maintain at 0.25 - 0.35 Maintain 4 reps of initial 8’x8’ spacing 0.10 – 0.20 (4 plots) Measurement ages: 13, 15, 16, 17, 19, 22, 25, 28 ,31, 34, 37
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Self-Thinning / Reineke’s Stand Density Index
3.5 5.2 7.8 11.6 17.3
Quadratic mean dbh (in.)
2440
1480
900
550
330
200
8’x8’
5’x5’
500400
Source: Husch, Beers & Kershaw, Forest Mensuration - 4th Edition
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Self-Thinning / Relative Density Index (D&F)
221 384 665 1153 1998
Trees Per acre
Mean Tree Volume (ft3)116
39
28
13
1.4
0.5
0.15
0.55
Maximum Size-Density
0.15
0.55
0.55
0.15
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Growth vs. Growing Stock / Langsaeter’s Hypothesis
0 20 40 60 80 100 0 20 40 60 80 100
V
olum
e In
crem
ent (
Cun
its/a
c/ye
ar)
V
olum
e In
crem
ent (
Cun
its/a
c/ye
ar)
1
Vol
ume
Incr
emen
t (C
units
/ac/
year
)
2
3
4
5
1
2
3
4
5
Volume (Cunits/acre)
1
2
3
4
5
Volume (Cunits/acre) Volume (Cunits/acre)
Age 17
Age 23
Age 35
Source: USFS Research Paper PNW-RP-537
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Growth vs. Growing Stock / Langsaeter’s Hypothesis
Vol
ume
Incr
emen
t (C
u.ft.
/ac/
year
)
Volume (Cubic feet /acre)
Volume (Cubic feet /acre) Volume (Cubic feet /acre)
Age 17
Age 23
Age 35
Source: USFS Research Paper PNW-RP-537
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Langsaeter: Growth / Growing Stock – Age 23
Volume (Cubic feet per acre)
An
nu
al
Vo
lum
e I
nc
rem
en
t (C
ub
ic f
ee
t /
ac
re /
ye
ar)
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Langsaeter: Growth / Growing Stock – Age 35
Volume (Cubic Feet Per Acre)
An
nu
al
Vo
lum
e I
nc
rem
en
t (C
ub
ic F
ee
t /
Ac
re /
Ye
ar)
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Yield Summary by Treatment: Total Age 37C
um
ula
tive
Mo
rta
lity
(ft3 )
To
tal V
olu
me
Pro
du
ced
(f
t3 )
Qu
ad
ratic
DB
H (
inch
es)
– A
ge
37
T
ota
l Ha
rve
ste
d V
olu
me
(ft3
)
Number of Thinnings 3 4 3 3 1 3 1 0 0
5
10
15
Quadratic Mean DBH 19.0 13.1 13.5 10.2 11.2 12.5 13.0 9.3 11.0
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Langsaeter Study: Observations through Age 37
No firm evidence that a growth/growing stock “plateau” (phase III) was achieved.
Reductions in growing stock, due to thinning, initially resulted in reductions in periodic growth.
More aggressive thinning treatments captured mortality and concentrated subsequent growth on fewer, larger trees (as expected).
Douglas-fir does not stagnate (Phase IV/V) – loses growing stock through aggressive mortality!
No significant “bonus wood” was produced. (i.e. total production was either reduced or stayed the same -- but not increased -- by repeated thinning). Future growth on the thinned 40-50’s?
The 8’x8’ spacing, allowed to achieve RD 0.50 followed by thinning to RD 0.25 produced a nice combination of volume and QMD!
Self-thinning “laws” were validated as useful constructs!
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Langsaeter Study: Shortcomings…
Limited (high) initial planting densities (680 & 1742 tpa)
Small plots Final thinning treatment at total age 22 Most thinning strategies not economically viable
(like LOGS) Single installation on a high site
Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007Western Mensurationists Meeting, Kelowna, BC – June 24-26, 2007
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Questions / Comments