Biomechanics Series
WSFNR11-22
May 2011
Estimating Tree Stem
& Branch Weight
by Dr. Kim D. Coder, Professor of Tree Biology & Health Care
Estimating forces and loads applied in tree structural systems require determining weight of
different tree parts and portions. One of the most difficult measures to estimate is green xylem weight in
branches and stems. Wood weight can be precisely and accurately determined in the laboratory from
small samples at oven-dry moisture contents. Within living trees, moisture content values are difficult
to determine accurately. The moisture content alone of living tree xylem and associated tissue can vary
by as much as 30% to 250% more than the weight of any woody material.
To estimate branch weight, woody material weight must be added to moisture (water) weight.
Intercellular spaces, cell wall areas, and interior cell spaces all hold water in various forms and strength
of chemical attachment. Moisture contents vary by wood type (heartwood / sapwood), location in crosssection (depth in wood), and by species. Green wood and living tissues at the smallest level are bathed
in hydration layers of various thicknesses. Liquid water can be held within nonfunctional xylem elements. Tree life covers itself with water on an ionic, cellular, and tissue scale. In some cases, and in
some species, water can make up a majority of the weight of a branch. As such, it is critical water
weight (moisture content) be incorporated into estimates of living / green wood weight.
Volume
Table 1 estimates how many cubic feet are in a given branch section. The estimate is based upon
the branch segment average diameter (outside periderm) and length. Periderm weight, cavities, overgrown foreign materials, and atypical growths are not included in this volume estimate and subsequent
weight calculation. Cubic feet volumes are calculated using a geometric average diameter outside the
periderm using the small end diameter and large end diameter of the branch segment. This geometric
average diameter value is used to calculate number of cubic feet in a branch segment.
Weight
Table 2 provides green wood density values per cubic foot for a variety of tree species. Green
wood moisture contents used in the density calculation are an average of heartwood and sapwood moisture contents cited for each species. Branch segment weight is estimated by multiplying the number of
cubic feet in a branch segment by green wood density in pounds per cubic foot. Figure 1 defines the
calculations graphically. The result is an estimate (in pounds) of branch segment weight.
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Telephone 706-542-7912 (V/TDD).
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Table 1: Number of cubic feet in a wooden cylinder with a
given diameter or circumference (in inches), and with a
length between 1 and 13 feet long.
Note table values are rounded approximations.
diameter circumference
(inches)
(inches)
1
2
3
4
5
length (feet)
6
7
8
9
10
11
12
13
6.3
9.4
13
16
0.02
0.05
0.1
0.1
0.04
0.10
0.2
0.3
0.07
0.15
0.3
0.4
0.09
0.20
0.35
0.6
0.11
0.25
0.4
0.7
0.13
0.30
0.5
0.8
0.15
0.35
0.6
1.0
0.17
0.40
0.7
1.1
0.2
0.4
0.8
1.2
0.2
0.5
0.9
1.4
0.2
0.5
1.0
1.5
0.3
0.6
1.1
1.6
0.3
0.6
1.1
1.8
6
7
8
9
10
19
22
25
28
31
0.2
0.3
0.4
0.4
0.6
0.4
0.5
0.7
0.9
1.1
0.6
0.8
1.1
1.3
1.6
0.8
1.1
1.4
1.8
2.2
1.0
1.3
1.8
2.2
2.7
1.2
1.6
2.1
2.7
3.3
1.4
1.9
2.4
3.1
3.8
1.6
2.1
2.8
3.5
4.4
1.8
2.4
3.1
4.0
5.0
2.0
2.7
3.5
4.4
6
2.2
2.9
3.8
5
6
2.4
3.2
4.2
5
7
2.6
3.5
4.5
6
7
11
12
13
14
15
35
38
41
44
47
0.7
0.8
0.9
1.1
1.2
1.3
1.6
1.8
2
2.5
2.0
2.
2.8
3
3.7
2.6
3.
3.7
4
5
3.3
3.9
4.6
5
6
4.0
5
6
6
7
4.6
6
7
8
9
5
6
7
9
10
6
7
8
10
11
7
8
9
11
12
7
9
10
12
14
8
9
11
13
15
9
10
12
14
16
16
17
18
19
20
50
53
57
60
63
1.4
1.6
1.8
2.0
2.2
3
3
4
4
4
4
5
5
6
7
6
6
7
8
9
7
8
9
10
11
8
10
11
12
13
10
11
12
14
15
11
13
14
16
18
13
14
16
18
20
14
16
18
20
22
15
17
20
22
24
17
19
21
24
26
18
21
23
26
28
21
22
23
24
25
66
69
72
75
79
2.4
2.6
2.9
3.1
3.4
5
5
6
6
7
7
8
9
9
10
10
11
12
13
14
12
13.
14
16
17
14
16
17
19
21
17
19
20
22
24
19
21
23
25
27
22
24
26
28
31
24
26
29
31
34
27
29
32
35
38
29
32
35
38
41
31
34
38
41
44
26
27
28
29
30
82
85
88
91
94
3.7
4.0
4.3
4.6
4.9
7
8
9
9
10
11
12
13
14
15
15
16
17
18
20
18
20
21
23
25
22
24
26
28
30
26
28
30
32
34
30
32
34
37
39
33
36
39
41
44
37
40
43
46
49
41
44
47
51
54
44
48
51
55
59
48
52
56
60
64
2
3
4
5
Dr. Kim D. Coder, Warnell School, University of Georgia
2
Table 1: Number of cubic feet in a wooden cylinder with a
given diameter or circumference (in inches), and with a
length between 1 and 13 feet long. (continued from page 2)
Note table values are rounded approximations.
diameter circumference
(inches)
(inches)
1
2
3
4
5
length (feet)
6
7
8
9
10
11
12
13
31
32
33
34
35
97
101
104
107
110
5
6
6
6
7
11
11
12
13
13
16
17
18
19
20
21
22
24
25
27
26
28
30
32
33
32
34
36
38
40
37
39
42
44
47
42
45
48
51
54
47
50
54
57
60
52
56
59
63
67
58
62
65
69
74
63
67
71
76
80
68
73
77
82
87
36
37
38
39
40
113
116
119
123
126
7
8
8
8
9
14
15
16
17
18
21
22
24
25
26
28
30
32
33
35
35
37
39
42
44
42
45
47
50
52
50
52
55
58
61
57
60
63
66
70
64
67
71
75
79
71
75
79
83
87
78
82
87
91
96
85
90
95
100
105
92
97
102
108
114
41
42
43
44
45
129
132
135
138
141
9
10
10
11
11
18
19
20
21
22
28
29
30
32
33
37
39
40
42
44
46
48
51
53
55
55
58
61
63
66
64
67
71
74
77
73
77
81
85
88
83
87
91
95
100
92
96
101
106
111
101
106
111
116
122
110
116
121
127
133
119
125
131
137
144
46
47
48
49
50
145
148
151
154
157
12
12
13
13
14
23
24
25
26
27
35
36
38
39
41
46
48
50
52
55
58
60
63
66
68
69
72
75
79
82
81
84
88
92
96
92
96
101
104
109
104
109
113
118
123
116
121
126
131
136
127
133
138
144
150
139
145
151
157
164
150
157
164
170
177
55
60
65
70
75
173
189
204
220
236
17
20
23
27
31
33
39
46
54
61
50
59
69
80
92
66
79
92
107
123
83
98
115
134
155
99
118
138
160
184
116
138
161
187
215
132
157
184
214
246
149
177
208
241
276
165
197
231
267
307
182
216
254
294
338
198
236
277
321
368
215
255
300
348
399
80
85
90
95
251
267
283
299
35
39
44
49
70
79
88
99
105
118
133
148
140
158
177
197
175
197
221
246
210
237
265
296
245
276
309
345
279
315
354
394
314
355
398
443
349
394
442
493
384
434
486
542
419
473
530
591
454
513
575
640
Dr. Kim D. Coder, Warnell School, University of Georgia
3
Table 2: Average calculated wood density for selected
species at greenwood specific gravity and average
moisture contents (MC%) for combined heartwood
and sapwood.
Average Moisture Content or MC% =
( ( average heartwood moisture content ) + ( average sapwood moisture content ) )
species
common
name
wood
density
(lbs/ft3)
average
MC
(%)
2 ).
greenwood
specific
gravity
green ash
white ash
American basswood
American beech
black cherry
49.6
51.5
40.9
57.7
46.9
50
50
11
65
60
0.53
0.55
0.32
0.56
0.47
Eastern cottonwood
American elm
red elm
pecan
mockernut hickory
60.0
56.0
58.4
67.4
65.9
160
95
95
80
65
0.37
0.46
0.48
0.60
0.64
pignut hickory
shagbark hickory
honeylocust
black locust
Southern magnolia
68.0
65.9
61.8
68.0
56.0
65
65
65
65
95
0.66
0.64
0.60
0.66
0.46
red maple
silver maple
sugar maple
black oak
cherrybark oak
55.0
49.4
59.4
62.9
68.5
80
80
70
80
80
0.49
0.44
0.56
0.56
0.61
laurel oak
scarlet oak
Southern red oak
water oak
willow oak
62.9
67.4
58.4
62.9
62.9
80
80
80
80
80
0.56
0.60
0.52
0.56
0.56
Dr. Kim D. Coder, Warnell School, University of Georgia
/
4
Table 2: Average calculated wood density for selected
species at greenwood specific gravity and average
moisture contents (MC%) for combined heartwood
and sapwood. (continued from page 4)
Average Moisture Content or MC% =
( ( average heartwood moisture content ) + ( average sapwood moisture content ) )
species
common
name
wood
density
(lbs/ft3)
chestnut oak
live oak
overcup oak
post oak
swamp chestnut oak
64.0
89.9
64.0
67.4
67.4
80
80
80
80
80
0.57
0.80
0.57
0.60
0.60
white oak
sassafras
sweetgum
American sycamore
black gum
67.4
49.8
60.3
64.6
58.8
80
90
110
125
105
0.60
0.42
0.46
0.46
0.46
black walnut
yellow-poplar
baldcypress
Atlantic white-cedar
Eastern red-cedar
58.8
48.7
65.5
35.8
50.8
85
95
150
85
85
0.51
0.40
0.42
0.31
0.44
Eastern hemlock
Eastern white pine
loblolly pine
longleaf pine
pitch pine
49.8
37.1
51.3
59.0
51.3
110
75
75
75
75
0.38
0.34
0.47
0.54
0.47
sand pine
shortleaf pine
slash pine
Virginia pine
red spruce
50.2
51.3
59.0
49.1
42.7
75
75
75
75
85
0.46
0.47
0.54
0.45
0.37
Dr. Kim D. Coder, Warnell School, University of Georgia
average
MC
(%)
/
2 ).
greenwood
specific
gravity
5
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small-end
diameter (in)
length
(ft)
Measure small-end diameter (ds)
and large-end diameter (dl).
Geometric average diameter =
dx = 0.71 x
(ds2 + dl2)
Volume in cubic feet =
(0.00182) x (0.5 x dx)2
x (length x 12)
BRANCH
SEGMENT
Average moisture
content (MC%) of
green wood =
( ( sapwood +
heartwood ) / 2)
large-end
diameter (in)
Density (lb/ft3) =
62.4 X (specific gravity) X ( 1 + MC% )
moisture content (MC%) is in decimal form
Dr. Kim D. Coder, Warnell School, University of Georgia
6