1

Effect of Density Management and Fertilization in SMC Type I Installations on

BH Branch Diameter

Rapeepan Kantavichai, PhD studentDavid Briggs

Eric Turnblom

April 25, 2007SMC Spring Meeting

Vancouver, WAFile: Type_I_Branch_T_F_April_2007.ppt

2

Background

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Fahey, T.D., J.M. Cahill, GT.A. Snellgrove, L.S. Heath. 1991. Lumber and Veneer Recovery from Intensively managed Young-Growth Douglas-fir. PNW-RP-437. USDA Forest Service PNW Research Station, Portland, OR.

Knot diameter & product grade yielda. Largest knot on the logb. LLAD “largest limb average diameter” = branch index (bix)

Grades of MSR Lumber Recovered

Is there a relationship between the branch index of a log and a simple tree measure?

Knot diameters observed on log surface

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Is there a relationship between the LLAD of a log and a simple tree measure?

Diameter of largest branch at bh region

LLAD or BIX of 16 ft log

• Focus on BH region• Simple to measure• Hypothesis:

There is a relationship between the LLAD of a log and the diameter of the largest branch in the BH region (DLLBH) of the parent tree

Next higher whorl

1st whorl above BH

Breast height

½ distance

½ distance

Next lower whorl

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Can translate a simple BH measurement into a log quality index or vice-versa

5 m log LLAD vs largest BH limb: Twin Peaks # 736

y = 0.7045x + 10.718R2 = 0.5813

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

LLBH, mm

5m L

og L

LAD

, mm

DLLBH

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Branch Diameter before crown recession• Before crown recession above the

branch it is alive and growing• Diameter at stem surface is increasing

Thin effect on mean branch diameter of trees in a stand

Chainsaw effect increase, decrease, or not change depending on type of thinning

Response of residual stand increased diameter growth for a longer time (slower crown recession)

Fertilizer effect on mean branch diameter of trees in a stand

Increased growth Growth models that predict branch

diameter at crown recession do not reflect what is observed on log surface later next slide

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Branch diameter after crown recession• After crown recession above the

branch it is dead• Diameter at stem surface is

decreasing (branch taper, loss of bark, shrinkage) Thin effect on mean branch

diameter of trees Chainsaw effect increase,

decrease, or not change depending on type of thinning

Response of residual stand may accelerate stem growth over dead tapered branch

Fertilizer effect on mean branch diameter of trees

May accelerate stem growth over the dead tapered branch

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Experimental Sites

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Sample: 9 Type I Installations with T/F Trials

Installation

County, State

Elevarion, ft

Slope, %

Aspect

Site Index_50, ft 1

Site Index_30, ft 2

Planting Date

Stock Type

Establishment Y

r

Avg. Trees/A

cre @

Establishment 3

Establishment A

ge from

Planting

704, Ostrander Road Cowlitz, WA 600 20 270 120 (II) 82 Jan-742-0,2-1,1-11987 676 13705, East Twin Creek King, WA 2700 30 180 90 (IV) 74 Jan-76 1-1 1987 690 11708, Copper Creek Lewis, WA 900 5 999 125 (II) 91 Jan-81 1-1 1988 378 7713, Sauk Mountain Skagit, WA 793 5 180 120 (II) 89 1978 NA 1988 526 10718, Roaring River Linn, OR 1100 10 888 128 (II) 92 Jan-82 2-1,2-0 1989 560 7722, Silver Creek MainlineMarion, OR 2200 10 270 120 (II) 72 Feb,77 2-0 1989 470 12725, Sandy Shore Jefferson, WA 550 0 999 120 (II) 89 Dec, 80 1-0 1990 512 10726, Toledo Lincoln, OR 300 10 225 135 (I) 93 Jan-84 1-1 1990 289 6736, Twin Peaks King, WA 600 40 270 120 (II) 93 Mar, 84 2-0 1992 384 8Mean 498 91 Site Index-50, based on breast-height age, is from King (1966); site class in ()

3 Average of the 4 ISPA plots on each Installation

2 Site Index-30, based on age from seed, is from Flewelling et.al (2001) and is the mean for all plots on the installation calculated after 2 remeasurements or 8 years after establishment

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Management regimes in the 9 Type I T/F TrialsNumber Name Description 1 ISPA_NoThinNoFert Plots remained at their Initial Stems Per acre (ISPA) with

no further thinning and no fertilization 2 ISPA_RepThinNoFert Plots remained at their initial density (ISPA), but were

repeatedly thinned† later. No fertilization. 3 ISPA_RepThinFert Plots remained at their initial density (ISPA), but were

repeatedly thinned later. Urea was applied at establishment and every four years later.

4 ISPA/2_MinThinNoFert Plots were spaced to half their initial density (ISPA/2) with minimal thinning‡ later. No Fertilization.

5 ISPA/2_MinThinFert Plots were spaced to half their initial density (ISPA/2) with minimal thinning later. Urea was applied at establishment and every four years later.

6 ISPA/4_NoThinNoFert Plots were spaced to one-fourth of their initial density (ISPA/4) with no further thinning. No fertilization.

7 ISPA/4_NoThinFert Plots were spaced to one-fourth of their initial density (ISPA/4) with no further thinning. Urea was applied at establishment and every four years later.

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Sample

• 6 plots x 9 installations = 54 plots• DLLBH from 2257 trees (about 40 trees/plot)• planted 1974-84 (289-690 tpa; ave 500)• established 1987-92 (age 6-13; ave 9)• fertilized with 200 lb N as urea at establishment & every 4

years since• 7 of 9 are King’s site class II; we used Flewelling’s SI in

the analysis • 22-32 years old at DLLBH measurement (2002-2005)

• Virtually all BH branches were dead!

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Analysis

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VARIABLE DESCRIPTION Dependent

DLLBH Diameter of the largest limb in the BH region of a tree, mm Independent (treatment effects)

ISPA1 ISPA2 ISPA4

Binary (0,1) variables. Code = 1 if plot has 100% (ISPA1), 50% (ISPA2), or 25% (ISPA4) of trees per unit area at plot establishment; code = 0 otherwise

FERT Binary (0,1) variable. Code = 0 if plot was not fertilized; code = 1 if fertilized with 224 kg/ha (200 lb/ac) N as urea at establishment and every 4 years since.

Independent (plot conditions) ISTEMS Average trees per unit area present at establishment on the entire

installation before spacing to the ISPA densities IRD Curtis’ relative density at establishment before spacing to the ISPA

densities SI30 Flewelling’s 30 year site index calculated from plot data closest to age 20

PSTEMS Trees per unit area present after establishment re-spacing on each plot. PRD Curtis’ relative density at establishment after re-spacing each plot

Independent (time of crown recession above BH) Y_Until_CR Elapsed years from spacing at establishment until the crown receded above

BH (used first measurement cycle when crown height > BH) Y_Since_CR Elapsed years since the crown receded above BH until the latest BH branch

measurement Y_total Sum of Y_Until_CR and Y_Since_CR

Independent (arithmetic mean tree variables per plot) DBH Diameter at breast height HT Total height

HCB Height to crown base HT/DBH Ratio of total height to dbh

CL Crown length = HT-HCB CR Crown ratio = 1-HT/HCB

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Variables

Defined on next slide

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Crown Recession Variables

Y_Until_CR (live branch)Y_Since_CR (dead branch)

Measurement pointsOffset due to bark

Y_Total = Y_Since_CR + Y_Until_CR

Plot establishment Our measure of crown

recession above BH; no interpolation

4 yrs 4 yrs4 yrs4 yrs

• Time of crown recession above BH (death of the largest BH branch) Number of years since establishment until the first 4-year measurement when the crown base was above BH; no

interpolation. Also know years since crown recession until the DLLBH measurement.

• DLLBH decreases as the bole grows over dead branch (taper, bark loss, & shrinkage)

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Plot (Stand) Level Statistics Variables Variable N Mean Standard

Deviation Minimum Maximum

DLLBH, mm 54 25.3 6.95 12.7 43.3 ISTEMS, treesha-1 54 1297 421.8 697 2550

IRD 54 29.0 17.06 8 75 SI30, m 54 26.5 2.35 21.6 29.9

PSTEMS, treesha-1 54 685.0 455.5 188 2096 PRD 54 15.0 12.61 3 60

Y_Until_CR 54 9.3 3.01 4 16 Y_Since_CR 54 5.0 3.77 0 13

Y_total 54 14.3 2.02 12 17 DBH, cm 54 26.9 4.75 18 38

HT, m 54 18.8 2.43 16 25 HCB, m 54 7.5 3.08 2.1 14.0

HT/DBH, cm/cm 54 71.6 12.83 48 101 CL, m 54 11.4 2.09 8 18 CR, % 54 60.5 13.46 39.6 85.6

1

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Confounding Problem with Stand Age• The 5 Installations planted 1980 & earlier were denser and on

lower site quality than the 4 planted 1981 & later

Change in management planting philosophy Bad luck in what was offered and when AGE picks these historical patterns up branch diameter decreases

with age not biologically meaningful so we dropped it.

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Models• Model 1: Fixed treatment effects plus installation-wide pre-

treatment stand variables

• Model 2: Substitute actual post-treatment plot variables

• Model 3: Use mean tree variables on each treatment plot

• Model 4: Combination of tree, treatment effect, & stand

30, , ,

_ _ , _ _ , _ int

DLLBH ISPA FERT ISTEMS SI IRD AGE

Y Until CR Y Since CR Y Total eractions error

30, , ,

_ _ , _ _ , _ int

DLLBH FERT PSTEMS SI PRD AGE

Y Until CR Y Since CR Y Total eractions error

, , , , , intHTDLLBH DBH HT HCB CL CR eractions errorDBH

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Statistical Analysis (all in SAS)• Backward elimination

Main effects2-way interactions (centered)

• Fit & Assumption ChecksAIC, RMSE, R2

adj

Residuals Test normality & homogeneous varianceHold-out procedure: use model based on 8 installations to

predict 9th • Independent test:

Predict of DLLBH on other Type I’s

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Results

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Model 1 Fixed treatment effects, installation-wide pre-treatment stand

conditions, timing of crown recession above BH

DLLBH = -8.745 ISPA1 – 5.322 ISPA2 - 2.244 ISPA4 + 2.121 FERT – 0.0059 ISTEMS + 1.439 SI30 + 1.674 IRD - 0.937 Y_Since_CR

(RMSE = 2.94, radj2 = 0.82)

No interactions were significant DLLBH decreases with more original trees per acre and more time

since the crown receded above BH (growth over dead tapered branches)

DLLBH increases if trees were on higher site quality and larger for the number of original trees and increases with PCT to wider spacing and use of fertilizer.

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Model 2Individual plot stand conditions just after treatment, timing

of crown recession above BH

DLLBH = 23.441 + 2.371 FERT – 0.00755 (PSTEMS - 685) + 1.052 (SI30 – 26.5) - 0.825 (Y_Since_CR – 5) – 0.0011 (PSTEMS - 685) (SI30 – 26.5) + 0.000464 (PSTEMS - 685) (Y_Since_CR – 5)

(RMSE = 2.80, radj2 = 0.84)

DLLBH decreases with more trees per acre remaining after PCT and more time since the crown receded above BH (growth over dead tapered branches)

DLLBH increases if trees were on higher site quality with use of fertilizer. The effect of site index is moderated by the density of trees higher density

on a site results in lower DLLBH (earlier crown recession above BH hence longer time to grow over dead tapered branch)

The effect of Y_Since_CR is moderated by the density of trees higher densities increase DLLBH (slower rate of growth over dead tapered branch)

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Model 3 Use Descriptors of Mean Tree on Treatment Plots

DLLBH = 25.598 + 1.258 (DBH – 26.9) – 1.972 (HT – 18.8) – 0.0923 (HT – 18.8)(DBH – 26.9)

(RMSE = 2.52, radj2 = 0.87)

DLLBH decreases with greater dbh DLLBH decreases with greater height; taller trees are likely to have a

crown that has receded further above BH more time since branch death for bole to grow over dead tapered branches

The effect of dbh is moderated by height; taller trees reduce DLLBH more than shorter trees of the same DBH tall vs short trees differ in when crown recession occurs hence time to grow over a dead branch.

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Model 4Combining Average Tree & Treatment/Stand Variables

• DLLBH = 5.800 + 0.732 SI30 + 1.017 DBH – 1.351 HT – 0.387 Y_Since_CR(RMSE = 2.18, radj

2 = 0.90)

• DLLBH = 1.22 + 0.724 SI30 + 1.006 DBH – 1.487 HT + 0.094 CR(RMSE = 2.19, radj

2 = 0.90)

• DLLBH = 25.511+ 0.739 (SI30 – 26.5) – 0.363 (Y_Since_CR – 5.0) + 1.028 (DBH - 26.9) – 1.294 (HT – 18.8) – 0.069 (DBH - 26.9) (HT – 18.8)(RMSE = 1.99, radj

2 = 0.92)

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Model 5Can we use LIDAR?

• Using just height, crown and tree count data

DLLBH = 2.241 + 0.38 CR (RMSE = 4.74, radj

2 = 0.53)

• If site index and treatment information from stand records are included the model improves

DLLBH = -14.497 + 2.61 FERT +1.079 SI30 -0.00525 PSTEMS -0.714 CL + 0.335 CR

(RMSE = 2.95, radj2 = 0.82)

• The potential for linking quality measures with LIDAR needs further exploration

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Using the Models

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Models 1, 2, 4a & 4c use Y_Since_CRNeed to estimate when crown recession occurs

• At each 4-year measurement calculate the % of trees in each treatment plot with crown above BH (n = 241)

• Logistic model:

• Enter values for PSTEMS and SI and calculate % of trees with crown above BH as stand age increases (Table next slide)

• Example: Suppore wish to estimate DLLBH at age 25 of a 1200 tpha stand growing on site 20m land

( )

1 2( ) ( )1

f x

if x

eP where f x X X Xe

30( ) 27.726 0.7806 0.511 0.00185f x AGE SI PSTEMS

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% of Trees with Crown above BHManager can decide on threshold, say 85% (yellow)

Age 800 1000 1200 1400 1600 1800 2000 800 1000 1200 1400 1600 1800 2000 800 1000 1200 1400 1600 1800 2000

10 0% 0% 0% 0% 0% 0% 0% 0% 0% 1% 1% 1% 2% 3% 4% 6% 9% 12% 16% 22% 29%11 0% 0% 0% 0% 0% 0% 1% 1% 1% 2% 2% 3% 5% 7% 9% 12% 17% 23% 30% 38% 47%12 0% 0% 0% 0% 1% 1% 1% 2% 2% 3% 5% 7% 9% 13% 18% 24% 31% 39% 48% 57% 66%13 0% 0% 1% 1% 1% 2% 3% 3% 5% 7% 10% 14% 19% 25% 32% 40% 49% 58% 67% 75% 81%14 1% 1% 1% 2% 3% 4% 5% 7% 10% 14% 19% 26% 33% 42% 50% 59% 68% 75% 82% 87% 90%15 1% 2% 3% 4% 6% 8% 11% 15% 20% 26% 34% 43% 52% 61% 69% 76% 82% 87% 91% 93% 95%16 3% 4% 6% 8% 11% 16% 21% 27% 35% 44% 53% 62% 70% 78% 83% 87% 91% 94% 95% 97% 98%17 6% 8% 12% 16% 22% 29% 37% 45% 54% 63% 71% 78% 84% 88% 91% 94% 96% 97% 98% 99% 99%18 12% 17% 23% 30% 38% 47% 56% 64% 72% 79% 84% 89% 92% 94% 96% 97% 98% 99% 99% 99% 100%19 23% 30% 39% 48% 57% 66% 74% 80% 85% 89% 92% 94% 96% 97% 98% 99% 99% 99% 100% 100% 100%20 40% 49% 58% 67% 74% 81% 86% 89% 92% 95% 96% 97% 98% 99% 99% 99% 100% 100% 100% 100% 100%21 59% 68% 75% 81% 86% 90% 93% 95% 96% 97% 98% 99% 99% 99% 100% 100% 100% 100% 100% 100% 100%22 76% 82% 87% 91% 93% 95% 97% 98% 98% 99% 99% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100%23 87% 91% 94% 95% 97% 98% 98% 99% 99% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%24 94% 96% 97% 98% 99% 99% 99% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%25 97% 98% 99% 99% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%26 99% 99% 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%27 99% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%28 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%29 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%30 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%

20 3025Site index, m Site index, m Site index, m

Density, trees/ha

A stand with 1200 trees per hectare on a 20 m site will reach 85% crown recession above BH by age 22. Y_SINCE CR is measured after recession

To estimate DLLBH, at age 25, Y_SINCE CR = 4

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Models 3 and 4Use mean total height and mean DBH

• User may have HT40 and QMD from a model• Conversion equations for the 54 plots:

DBH = -1.033 + 1.017 QMD (RMSE = 0.242, radj2 = 0.99)

HT = 0.15 + 0.845 HT40 (RMSE = 0.054, radj2 = 0.93)

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Conclusion• At the treatment plot level, DLLBH can be predicted by several alternative

formulations flexibility for adoption

• Stand age is not in the DLLBH models; the older installations were planted more densely and on lower sites than the newer installations so density and site variables prevailed.

• Connectivity with LIDAR is promising and should be explored further.

• WARNING: Remember all BH branches were dead! These models would not be appropriate to use for trees with the live crown below BH.

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Future

• Counterpart models for predicting DLLBH for individual trees is underway and looks promising will present at IUFRO Forest Growth and Wood Quality Conference, Portland, OR. August 7-10, 2007.

• Extending the crown recession model to predict % of trees in a stand with the crown recession to any height (multinomial logit).

• Type III’s would be interesting so we can capture dynamics before/after crown recession above BH.