modeling branch characteristics in douglas-fir & western hemlock
DESCRIPTION
Modeling Branch Characteristics In Douglas-fir & Western Hemlock. Cast of Characters. Dr. Gero Becker Professor, Univ. of Freiburg, Germany, Visiting Scholar, SMC Dr. David Briggs Professor UW CFR, Director, SMC Dr. Olav Hoibo - PowerPoint PPT PresentationTRANSCRIPT
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Modeling Branch Characteristics In Douglas-fir
& Western Hemlock
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Cast of Characters
• Dr. Gero Becker– Professor, Univ. of Freiburg, Germany, Visiting Scholar, SMC
• Dr. David Briggs– Professor UW CFR, Director, SMC
• Dr. Olav Hoibo– Associate Professor, Agric. Univ. Norway, Visiting Scholar, SMC
• Eric Turnblom– Assistant Professor, UW CFR, Silviculture Project Leader, SMC
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Branches Respond Too!
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Outline
I. Number & Diameter of BH Branches: SMC ProtocolA. Type I Douglas-fir: PCT Effect on Average BH Branches in a
Stand
B. Type I Douglas-fir: PCT Effect on BH Branches of Individual Trees
C. Type I Western Hemlock: PCT Effect, status
D. Type III: Effect of Initial Spacing, status
II. PNW/Germany Cross-Comparison of DF Branch Diameter
III. Vertical Branch Profiles: DF & WH• Live/dead transition
• Branch/Stem Growth Dynamic
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I. Number & Diameter of BH Branches
• Douglas-fir branch protocol
• Type I and Type III Installations
• Taken on height trees on each plot (~42 trees)
• First whorl above BH – Diameter of largest branch in the whorl
– Total # branches in whorl >= 1/2 diameter of largest branch
– Total # branches in half-internode above & below the whorl that are >= 1/2 diameter of largest whorl branch
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A. Effect of PCT on Douglas-fir: Stand Level Models
• Sample– 19 Type I installations
– 57 plots ISPA, ISPA/2, ISPA/4
– 2397 trees
• Site Index is Flewelling (2001)
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A. Effect of PCT on Douglas-fir: Stand Level Modeling Method
a. Factorial Treatment Structure• 4 levels of Flewelling Site Index
• 3 levels of stand density (stems/acre)
• Covariates: Crown length, crown ratio Mean height, HT_40, mean height above BH Total age, BH age QMD, relative density
b. Plots with crown base < BH, > BH, and combined• No differences found with crown base below vs above BH
• Elapsed time since crown receded above BH is too short
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1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results
• as stems per acre increases total BH branch count decreases
• more shade on BH branches in denser stands
• 250 & 550 spa classes are not significantly different
• 125 spa class is significantly different 0
1
2
3
4
5
6
7
8
9
10
125 250 550
Stems per Acre Class#
BH B
ranc
hes
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1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results
• Site classes I, II, & III are not significantly different
• Site IV is significantly lower
• fewer resources to produce and maintain branches
• Also, total BH branch count– Decreases as average crown
length of stand increases (more shade on BH branches ?)
– Decreases as total stand age increases (self pruning?)
0
1
2
3
4
5
6
7
8
9
10
I III II IV
Site Index (Flewelling 2001)#
BH B
ranc
hes
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2. Effect of PCT on BH Nodal Branch Count of Type I Douglas-fir Stands: Results
0
1
2
3
4
5
6
7
8
9
10
I III II IV
Site Index (Flewelling, 2001)# B
H No
dal B
ranc
hes
• Site classes II & III are not significantly different
• Site classes II & IV are not significantly different
• Highest site class has about 1 more nodal branch (more resources for nodal branch production & survival?)
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3. Effect of PCT on BH Internodal Branch Count of Type I Douglas-fir Stands: Results
• Site classes II, & III are not significantly different
• Site III, I, & IV are not significantly different
• Site IV low due to fewer resources for production & survival of internodal branches
• Site I low due to competition and shading by more numerous nodal branches
• Also, BH internodal branch count– Decreases as average crown length of
stand increases (more shade on BH internodal branches ?)
– Decreases as total stand age increases (self pruning of internodals?)
0
1
2
3
4
5
6
7
8
9
10
II III I IV
Site Index (Flewelling, 2001)#
Inte
rnod
al B
H Br
anch
es
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4. Effect of PCT on BH Branch Count of Type I Douglas-fir Stands: Regression Models
C T 1.0
b0 b1(CL) b2(SPA )b3 (SPA 2 )b4(AGE)b5 (SI30 )b6 (SI302 )
Total = f (ave crown length, stems/acre, total age, site index)
Internodal = f (ave crown length, total age, site index)
)()()()()( 2305304
23210 SIbSIbAGEbAGEbCLbbCI
Nodal = Total - Internodal
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5. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Models
• All significantly different
• Lower stand density has larger BH branches (more space, less shade on BH, longer lived faster growing branches)
• Also, largest BH branch diameter– Increases as QMD increases
(bigger tree allometry?)
– Decreases as total stand age increases (point of maximum branch diameter becomes embedded inside the stem
0
0.2
0.4
0.6
0.8
1
1.2
1.4
125 250 550
Spems per AcreLa
rges
t BH
Bran
ch D
iam
eter
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6. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Model
D B 1.0
b0 b1(SPA )b2 (SPA 2 ) b3(QMD) b4(AGE) b5(AGE2 )
Average for Stand = f(QMD, total age, stems per acre)
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B. Effect of PCT on Douglas-fir: Individual Tree Modeling Method
a. Allometry with orthogonal quadratic polynomials for each of the 57 plots• Largest BH branch diameter vs other tree size measures: DBH best • Branch counts vs other tree size measures: DBH best
b. ANCOVA of 57 sets of coefficients• 4 levels of Flewelling Site Index• 3 levels of stand density (stems/acre)• Covariates:
Crown length, crown ratio Mean height, HT_40, mean height above BH Total age, BH age QMD, relative density
c. Plots with crown base < BH, > BH, and combined• No differences found with crown base below vs above BH• Elapsed time since crown receded above BH is too short
d. Regression
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1. Effect of PCT on BH Branch Counts of Douglas-fir Trees: Regression Model
Total = f(DBH, stems per acre, total age, site index, crown length)
Internodal: use stand level model = f(total age, site index, crown length)
)()()()()( 2305304
23210 SIbSIbAGEbAGEbCLbbCI
Nodal
= Total - Internodal
)(
)()()()()()(
0.1
0
23063054
23210
DBHb
SIzSIzAGEzSPAzSPAzCLzzCTi
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2. Effect of PCT on Largest BH Branch Diameter of Douglas-fir Trees: Regression Model
DBi 1.0
z0 z1(SPA ) z2 (SPA 2 ) z4 (AGE) z5(AGE2 )
DBH
b0 b1(SPA ) b2 (QMD) b3(QMD2 ) b4 (AGE )b5 (CL)
Individual Tree Largest BH Branch Diameter = f(DBH; stems per acre, total age, QMD, crown length)
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3. Conclusion: PCT of Douglas fir (Type I)
• Stand level variables (red) greatly improved individual tree model predictions!
• O. Hoibo has also found this in his crown profile research
• Status:– Article in review with Forest Science
• Future– Can we relate the BH results to the rest of the tree
– Can we develop a QC tool & prediction system that can be related to log grades/sorts
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C. Effect of PCT & Planting Density: W. Hemlock Protocol & Plans
• Type I and Type III Installations
• Taken on height trees on each plot (~42 trees)
• 3 foot zone centered on BH – Diameter of largest branch
– Total # branches >= 1/2 diameter of largest branch
• Started in 00/01 Field Season
• Preliminary analysis after 01/02 season
3 ft
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D. Effect of Planting Density: Douglas-fir
• Type III
• Data for 98/99, 99/00, 00/01, 01/02 seasons
• Preliminary work with 98/99 data– 8 installations; 6 plots each
– small trees on wider spacings tend to have larger branches than same age, larger trees on denser spacings
– another aspect of crossover effect?
• Will begin analysis this winter/spring
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II. PNW/Germany Cross-Comparison of DF Branch Diameter
Objectives:
Determine differences between branch diameter profile characteristics between two geographically disparate (Germany/PNW U.S.) Douglas-fir data sets
Gain insights into “best” modeling approach for future branch diameter modeling
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Available Data
• German data set– 4 plots: density ranges 150 -300 SPA; sites range 100 -140 ft@50
yr;
total ages range 32 -41 years
– 42 trees: DBH ranges 9.4 -16.1 in.; total heights range 62 -89 ft;
HCB ranges 25.6 -47.6 ft.
• SMC ‘Crown Study’ data set – 66 plots: density ranges 80 -600 SPA; sites range 80 -140 ft@50 yr;
total ages range 9 -36 years
– 562 trees: DBH ranges 1.0 -18.3 in.; total heights range 7.4 -104.7 ft;
HCB ranges 0 -67.1 ft.
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Testing Equations
• Wobst/Becker Equation:
• Maguire, et al. (1999) Equation:
BD (3.0 aRDFT)d e( b.RDFT )
a f (DBH, Ht, HOD, DOH,HCB,CR,D2 H)
b f (a), d is a parameter
BD (1CW 2 )WC
W 1 Z0.5
C 3Z 4
Z h / CL, h is height above crown base
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Branch Diameter Profile Comparison
• Upper curve (red) is Wobst/Becker model
• Lower curve (maeve) is Maguire et al.
• Upper is for live/dead branches, lower is for live only
0.1 0.2 0.3 0.4RELDIS
20
30
40
BDWB
BDM
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Residual Patterns
Wobst/Becker Maguire, et al.
0.1 0.2 0.3 0.4 0.5
RELDIS
-30
-20
-10
0
10B
D
W
B
_
R
0.1 0.2 0.3 0.4 0.5
RELDIS
-30
-20
-10
0
10
B
D
M
_
R
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Residuals Comparison
On average, Maguire et al. predicts larger branches, but ...
-30 -20 -10 0 10
BDM_R
BDM_R
-30 -20 -10 0 10
BDWB_R
BDWB_
-30 -20 -10 0 10
BDM_R
B
D
W
B
_
R
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Future Plans
• Use both models to predict branch diameters on trees in the SMC data set
• Determine which modeling approach / equation form is “best”
• Report results at IUFRO conference 2002
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III. Vertical Branch/Knot Profiles: DF• Douglas-fir Sample
– SMC Type I
– High Site, Medium Site
– ISPA , ISPA/2
– Similar age & ISPA
– 1 tree from each septile of DBH distribution (28 total trees)
– 7 trees x 4 plots = 28 trees
– Whorl 3, 6, 9, … 21 from top = 7 whorls/tree
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A. Transition from Live to Dead Knot: DF
• Branch Measurements– Azimuth
– Horizontal distance from cambium to
• Pith
• Live/dead transition
– Knot diameter at• Live/dead transition
• Cambium
• 1 branch diameter distance from stem surface (outside bark)
– All branches
• Data collected & analysis underway
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B. Relationship Between Stem & Branch Diameter Growth
• Measure– Smallest, median & largest of
the 7 tree sample from each plot
– Whorl # 6, 12, 18 from top
– Annual ring widths of stem cross-section
– Annual ring widths of smallest, median, & largest branch in each
• Data collected & analysis underway
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C. Vertical Branch/Knot Profiles: W. Hemlock
• Sample– Medium Site Type I Hemlock
– ISPA & ISPA/2
– 1 tree/septile of DBH distribution = 14 total trees
– 3 foot sections @ mid-live crown, live crown base, midway from crown base to ground, and at BH
• Transition from sound (live) to unsound (dead) knot– Sound knot length from pith
– Knot diameter (max) at transition – Largest 5 and next to smallest branch = 6 total
• Ring growth of stem & branch: all stem sections (4/tree)– Ring widths of stem
– Ring widths of largest, median, & smallest branch
• Samples collected: Anyone want a job?
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The End