1. 8/2/2011
Introduction
 Density is an important measure of wood quality
A comparison of earlywood-latewood demarcation
methods within an annual ring – A case study in  Large variation in wood density has been observed in
loblolly pine many tropical and temperate tree species
 Within-ring variation attributed to the formation of
F. Antony , L.R. Schimleck & R.F. Daniels earlywood (EW) and latewood (LW) within a ring
University of Georgia
Athens, GA
 Measure of within-ring variability in density can be used
as an indicator of wood uniformity
Introduction Introduction
 Within-ring density is expressed as an average of EW and
LW density  The threshold method is frequently used to identify the
transition from EW to LW in loblolly pine
 EW and LW density and their corresponding widths within
a ring depends on the definition(s) used by researchers
i d d h d fi i i ( ) db h  How well it agrees with the other methods?
 Several methods have been used to identify the  The objective of this study was to compare the three
demarcation between EW and LW (e.g. Mork’s index, different methods for EW-LW demarcation; Mork’s Index,
threshold method and the maximum derivative method). the threshold method and the inflection point method
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2. 8/2/2011
Materials and Methods Materials and Methods
Basic Density (kg m )
3
 20-radial strips (2 mm tangentially and 7 mm
800
longitudinally) from breast height increment cores
200
10 20 30 40 50 60 70
Distance from pith (mm)
 Radial strips were analyzed using Silviscan®
Radial Diame (m)
Air-dry density (AD),
eter
35
5
Tracheid wall thickness (WT),
20
Tracheid radial and tangential diameters (RD and TD) 10 20 30 40 50 60 70
Distance from pith (mm)
All properties measured at a resolution of 0.05 mm
 WT= P/8 - ½ (P2/16 – C/d)½
Wall Thickenss (m)
• P (perimeter) = 2(RD + TD)
6
• C (coarseness) = RD X TD X AD
4
2
• d = 1500 kg/m3 for all softwoods 10 20 30 40 50 60 70
Distance from pith (mm)
Materials and Methods Materials and Methods
 According to Mork (1928) a tracheid is said to be a Juvenile Wood Ring
latewood tracheid if
Morks index
1.0
• 2 X WT >= Lumen Diameter (LD)
0.4
• 2 X (2 X WT) >= LD
• where LD = RD – 2 WT 10 12 14 16
Distance from pith (mm)
 Following the second definition of Mork, we computed
Mature wood Ring
Mork’s Index (MI)
Morks index
2 x (2 x WT)
3
MI =
LD
1
 Transition from EW to LW is defined as the point within a 69.5 70.0 70.5 71.0 71.5 72.0
ring where MI  1 Distance from pith (mm)
2

3. 8/2/2011
Materials and Methods Materials and Methods
 Basic density (BD) at each radial position using the AD
data was computed as follows
800
Ring 20 Ring 21
700
BD = -22.0401 + 0.8902 AD
nsity (kg m )
3
600
 BD value of 480 kg/m3 was used in the threshold method
Basic Den
for defining the EW to LW transition
500
3
480 kg m
400
 It approximately corresponds to the mean BD of the zone
300
in which earlywood rapidly transitions to latewood in
loblolly pine
106 107 108 109 110 111
Distance from pith (mm)
Materials and Methods Materials and Methods
 The derivative method was based on identifying the Juvenile Wood Ring Mature Wood Ring
inflection point for the density profile of each individual ring
Basic Density (kg m )
1000
3
700
600
500
 A point on the curve is said to be the inflection point where
300
the second derivative of a function fitted to the curve will be
200
equal to zero 10 12 14 16 69.5 70.0 70.5 71.0 71.5 72.0
 Smooth splines were fitted to individual ring density profiles
(5df as smoothing parameter)
100
Derivative
Derivative
0
-100
 Point on the derivative plot at which the second derivative
-2000
-300
changed its sign from positive to negative was selected as the
EW and LW demarcation point 10 12 14 16 69.5 70.0 70.5 71.0 71.5 72.0
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4. 8/2/2011
Results and Discussion Results and Discussion
(a) (b)
Difference (Threshold-Inflection)
Difference (Morks-Inflection)
Inflection (mm)
Inflection (mm)
80
80
0.5
1.0
-0.5 0.0
40
40
0.0
0
0
5 10 15 5 10 15 0 20 40 60 80 100 0 20 40 60 80 100
D
Ring Number from pith Ring Number from pith Threshold (mm) Morks (mm)
(c)
Difference (Morks-Threshold)
1.5
Threshold (mm)
80
0.5
40
-0.5
0
5 10 15 0 20 40 60 80 100
Ring Number from pith Morks (mm)
Results and Discussion Results and Discussion
 MI consistently overestimated the amount of EW in an  MI (based on Silviscan®data) is a biased measure for
annual ring compared to the threshold and inflection point defining the EW-LW transition
methods
 Even though loblolly pine has an abrupt transition from
 The threshold method tends to be positively biased in EW to LW within an annual ring, it might take more time
ring
juvenile wood rings, i.e. it overestimates EW, compared to for tracheids to reach the defined threshold (2 X 2 X WT)
the inflection point method
 We plan to analyze several of the samples examined in this
 Despite the differences observed among the methods it is study using conventional microscopy to determine if MI
clear that all three methods show close agreement with continues to overestimate the amount of EW
each other
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5. 8/2/2011
Is a density of 480 kg/m3 a good threshold for EW-LW
demarcation in loblolly p ?
y pine
5

6. 8/2/2011
Introduction
Identification of representative sampling heights for
specific gravity and moisture content in plantation
grown loblolly pine
F. Antony , L.R. Schimleck & R.F. Daniels
University of Georgia
Athens, GA
Loblolly pine is the most important plantation species in the southern US
occupying more than half of the standing pine volume
Introduction Introduction
 Quality of wood - Physical, mechanical and anatomical
properties
 Estimates of wood properties - important for tree
improvement programs and for the appropriate
management of stands
 Nondestructive estimation - collection of an increment core
from a height that best represents whole tree wood
properties
Loblolly pine is used as a principal source of raw material in the pulp and paper
industry and for the production of lumber and composite wood products
1

7. 8/2/2011
Introduction Introduction
 Conventionally, for loblolly pine increment cores collected  Raymond and Muneri (2001)
at breast height (1.4 m) have been used • Must be accessible from the ground
• At a fixed height
 How well does a breast height core represent whole-tree • Adequately represents whole tree wood property values
p p
properties? • Does not change from site-to-site
• Specific gravity - Breast height SG as explanatory variable
• Wahlgren and Fassanacht (1959) - 53%
 Objectives
• Gilmore et al. (1961) - 50%
• To examine the efficacy of breast height increment cores to
• Moisture content
represent whole tree SG and MC
• Clark and Daniels (2000) - disks sampled from heights of 1.5
and 4.6 m (86%) • Identify the most representative sampling height for whole
tree SG and MC
Material and Methods Material and Methods
Three trees from each stand
Cross sectional disks 3.8cm
thick were collected from 0.15,
1.4m and then at 1.5m intervals
along the stem
g
Disk SG was measured using
green volume and oven-dry
weight
135 stands from six physiographic regions; 20-25 years old; Disk MC was measured using
planted at 1250 trees per ha and thinned to 625 trees per ha; green and oven dry weight
no fertilization and competition control
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8. 8/2/2011
Material and Methods Material and Methods
Material and Methods Material and Methods
 Whole-tree volume weighted SG and MC was computed  Whole tree volume weighted SG and MC = weighted
using the inside bark diameter, SG and MC measured from average SG and MC values for the disks that were sampled
each disk • the weight used was a ratio between the volume of each
segment and the total volume of the tree
 Volume
  A  Au  
• Each bolt segment - frustum of a paraboloid V  l L  Correlation between the observed disk SG and MC value
 2 
 
• Bottom segment – cylinder V  d 40000 L2 of each sampling height with the whole tree average SG
• Top segment - cone V  3  d 40000 L 
1 2 and MC was used to identify the best sampling height
 
 
 Total volume of the whole tree = sum of volume of each  A linear regression model was proposed to predict whole
section tree SG and MC values from different sampling heights
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9. 8/2/2011
Results Results
 High correlations exist between disk Sampled Specific
 A nonlinear decreasing trend was observed with height for and whole tree SG at several heights Height (m) Gravity
SG, an increasing trend with height was observed for MC between 1.4 and 7.6 m 0.3 0.88
1.4 0.91
3.0 0.92
 The strength of the correlations
4.6 0.93
quickly decreased at heights greater
 SG of trees from the south Atlantic and Gulf Coastal than 7.6 m
h 76
6.1 0.92
7.6 0.90
Plain’s were higher than the SG of trees from other regions
9.1 0.87
 Across all regions, samples 10.7 0.82
collected at 4.6 m best represent 12.2 0.81
whole tree SG
 MC was significantly higher for trees from the north 13.7 0.76
15.2 0.70
Atlantic Coastal Plain compared to other regions
16.8 0.66
18.3 0.69
19.8 0.73
Results Results
Specific gravity
 High correlations were observed for Sampled Moisture
south north Height (m) Content
Atlantic Atlantic
Upper Gulf Hilly heights ranging from 4.6 to 9.1 m
Height Coastal Piedmont Coastal Coastal 0.3 0.80
Coastal Coastal
Plain Plain Plain 1.4 0.82
Plain Plain
 For heights greater than 9.1 m, 3.0 0.88
0.3 0.88 0.87 0.88 0.87 0.80 0.80 correlations between disk and whole 4.6 0.92
1.4 0.91 0.92 0.91 0.92 0.84 0.84 tree MC fell rapidly
3.0
30 0.92
0 92 0.92
0 92 0.88
0 88 0.93
0 93 0.87
0 87 0.86
0 86 6.1 0.93
4.6 0.94 0.95 0.86 0.96 0.93 0.83 7.6 0.89
6.1 0.95 0.92 0.80 0.94 0.94 0.84
7.6 0.90 0.93 0.88 0.90 0.92 0.78
 Across all regions, samples 9.1 0.90
9.1 0.84 0.92 0.81 0.82 0.88 0.82 collected at 6.1 m best represent 10.7 0.83
10.7 0.80 0.62 0.68 0.83 0.82 0.80 whole tree MC 12.2 0.79
12.2 0.80 0.83 0.58 0.78 0.83 0.74
13.7 0.75
13.7 0.71 0.83 0.60 0.70 0.78 0.70
15.2 0.64 0.83 0.55 0.65 0.72 0.66 15.2 0.67
16.8 0.62 0.85 0.55 0.68 0.65 0.61 16.8 0.68
18.3 0.67 0.86 0.69 0.70 0.60 0.72
19.8 0.72 0.85 0.45 0.41 0.72 0.84 18.3 0.61
19.8 0.65
4

10. 8/2/2011
Results Discussion
Moisture Content
 High correlations were observed between disk SG and MC
south north
Atlantic Atlantic
Upper Gulf Hilly with volume weighted whole tree SG and MC for many of
Coastal Piedmont Coastal Coastal
Coastal Coastal
Plain Plain Plain
the sampled heights in the lower third of the tree
Height Plain Plain
0.3 0.83 0.78 0.68 0.76 0.85 0.81
1.4 0.83 0.65 0.76 0.80 0.87 0.86 • SG - samples collected between 1.4-6.1 m
3.0 0.86 0.86 0.75 0.90 0.89 0.89 • MC - samples collected between 4.6-6.1m
4.6 0.90 0.94 0.80 0.91 0.94 0.90
6.1 0.92 0.90 0.86 0.96 0.92 0.90
7.6
9.1
0.83
0.86
0.84
0.91
0.88
0.79
0.90
0.88
0.94
0.92
0.85
0.89
 For SG, breast height cores represented whole tree SG very
10.7 0.80 0.51 0.67 0.82 0.90 0.86 well with a marginal difference compared to the most
12.2 0.78 0.73 0.48 0.76 0.84 0.83 representative height
13.7 0.73 0.74 0.51 0.73 0.78 0.78
15.2 0.64 0.56 0.60 0.68 0.66 0.67
16.8
18.3
0.63
0.71
0.78
0.77
0.56
0.59
0.72
0.76
0.73
0.47
0.61
0.47
 A linear relationship was observed between whole disk SG
19.8 0.74 0.93 0.42 0.38 0.76 0.74 and MC with volume weighted whole tree SG and MC
irrespective of region
Discussion Discussion
Specific gravity Moisture Content
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11. 8/2/2011
Questions or Comments ?
6