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 Front Cover
 Title Page
 Acknowledgement
 Introduction
 Materials and methods
 Results and discussion
 Application
 Literature cited
 Back Cover
 Historic note






Group Title: Bulletin - Agricultural Experiment Stations, University of Florida ; 831 (technical)
Title: Potential stem biomass and energy content yields of Eucalyptus grandis and Eucalyptus robusta in south Florida
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00027457/00001
 Material Information
Title: Potential stem biomass and energy content yields of Eucalyptus grandis and Eucalyptus robusta in south Florida
Series Title: Bulletin Agricultural Experiment Stations, University of Florida
Alternate Title: Eucalyptus grandis
Eucalyptus robusta
Physical Description: 6 p. : ; 23 cm.
Language: English
Creator: Roeder, K. R ( Kenneth R )
Rockwood, D. L
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla.
Publication Date: 1982
 Subjects
Subject: Eucalyptus -- Florida   ( lcsh )
Energy crops -- Florida   ( lcsh )
Biomass energy -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: K.R. Roeder and E.L. Rockwood.
 Record Information
Bibliographic ID: UF00027457
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000401517
oclc - 10680590
notis - ACE7365

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Acknowledgement
        Acknowledgement
    Introduction
        Page 1
    Materials and methods
        Page 1
    Results and discussion
        Page 2
        Page 3
        Page 4
    Application
        Page 5
    Literature cited
        Page 6
    Back Cover
        Page 7
    Historic note
        Page 8
Full Text


Bulletin 831 (technical)


Potential Stem Biomass and Energy Content Yields of
Eucalyptus grandis and Eucalyptus robusta in
South Florida

K. R. Roeder and D. L. Rockwood










HUME LIBRARY

IiAY 221983

I.F.A.S. Univ. of Florida






Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
F. A. Wood, Dean for Research


December 1982











Potential Stem Biomass and Energy Content Yields of
Eucalyptus grandis and Eucalyptus robusta in
South Florida

K. R. Roeder and D. L. Rockwood



















AUTHORS
K. R. Roeder is Liaison Silviculturist, School of Forest Resources, North
Carolina State University, Raleigh. D. L. Rockwood is Associate Professor,
School of Forest Resources and Conservation, University of Florida, Gaines-
ville.








































ACKNOWLEDGEMENTS
The study reported here, which was conducted by the senior author as
Graduate Research Assistant, School of Forest Resources and Conservation,
University of Florida, was funded by Oak Ridge National Laboratory under
subcontract No. 9050. Trees utilized in the study were provided by Lykes
Bros., Inc., Palmdale, Florida.







INTRODUCTION
The determination of tree and stand biomass yield has gained
importance during the last decade, especially in the pulp and paper
industry (Hitchcock, 1978). This interest is partially due to a need to
increase yields through better technology, like whole-tree utiliza-
tion. The latest emphasis in the assessment of tree biomass has been
for conversion to energy. Biomass prediction equations and yield
tables have been compiled for various species under several silvi-
cultural and management schemes, including alternative stocking
levels and coppice regeneration (Clark and Schroeder, 1977; Phillips,
1977; Rockwood, et al., 1980; McClure, et al., 1981).
This study utilized existing stands of eucalypts to develop tree
prediction equations and tables that directly relate potential biomass
and energy yields to standard stand inventory and mill roundwood
scaling data.
MATERIALS AND METHODS
Adjacent compartments of 11-year-old Eucalyptus grandis Hill ex
Maid. and E. robusta Sm. in Glades County in south Florida were
sampled. Compartments of each species were inventoried with trees
categorized by DBH (diameter at 1.3 m) into five 5-cm diameter
classes (<15, 15-20, 20-25, 25-30, >30). For each species, two trees
in each diameter class were randomly selected for sampling. Forked
and apparently unhealthy trees were rejected, however.
Trees were felled, and the combined stem wood and bark to 75% of
total tree height was weighed to the nearest kilogram in the field.
Disks were removed at stump height, at breast height, and at 25, 50,
and 75% of total tree height for laboratory determination of specific
gravity (gm/cm3), moisture content (% and g/cm3) and energy values
(joules/g and joules/cm3) for wood and bark (Roeder, 1981). Volume-
weighted values for specific gravity and moisture content of wood and
bark were used to compute stem biomass and energy content to 75%
total height for each tree.
The predictive model, chosen for its biological accuracy, ease in
acquiring measurements, and ease of computation, was of the follow-
ing form:
Y = bo + blX, + ei
where Y = dependent variable
Xi = D2H (D = DBH in cm; H = total tree height in m) for
tree predictions; oven-dry biomas or green biomas in
other applications







INTRODUCTION
The determination of tree and stand biomass yield has gained
importance during the last decade, especially in the pulp and paper
industry (Hitchcock, 1978). This interest is partially due to a need to
increase yields through better technology, like whole-tree utiliza-
tion. The latest emphasis in the assessment of tree biomass has been
for conversion to energy. Biomass prediction equations and yield
tables have been compiled for various species under several silvi-
cultural and management schemes, including alternative stocking
levels and coppice regeneration (Clark and Schroeder, 1977; Phillips,
1977; Rockwood, et al., 1980; McClure, et al., 1981).
This study utilized existing stands of eucalypts to develop tree
prediction equations and tables that directly relate potential biomass
and energy yields to standard stand inventory and mill roundwood
scaling data.
MATERIALS AND METHODS
Adjacent compartments of 11-year-old Eucalyptus grandis Hill ex
Maid. and E. robusta Sm. in Glades County in south Florida were
sampled. Compartments of each species were inventoried with trees
categorized by DBH (diameter at 1.3 m) into five 5-cm diameter
classes (<15, 15-20, 20-25, 25-30, >30). For each species, two trees
in each diameter class were randomly selected for sampling. Forked
and apparently unhealthy trees were rejected, however.
Trees were felled, and the combined stem wood and bark to 75% of
total tree height was weighed to the nearest kilogram in the field.
Disks were removed at stump height, at breast height, and at 25, 50,
and 75% of total tree height for laboratory determination of specific
gravity (gm/cm3), moisture content (% and g/cm3) and energy values
(joules/g and joules/cm3) for wood and bark (Roeder, 1981). Volume-
weighted values for specific gravity and moisture content of wood and
bark were used to compute stem biomass and energy content to 75%
total height for each tree.
The predictive model, chosen for its biological accuracy, ease in
acquiring measurements, and ease of computation, was of the follow-
ing form:
Y = bo + blX, + ei
where Y = dependent variable
Xi = D2H (D = DBH in cm; H = total tree height in m) for
tree predictions; oven-dry biomas or green biomas in
other applications







bo, bl = regression coefficients
ei = th residual
RESULTS AND DISCUSSION
Based on a limited sample of two stands, E. grandis was found, on
the average, to be 10% taller than E. robusta. Combined wood and
bark ofE. robusta, on the other hand, exhibited 10% higher specific
gravity than E. grandis (Roeder, 1981). However, in traits investi-
gated, no statistically significant differences (0.05 level) between the
two species were detected within a given diameter class. A single
common prediction equation developed from these data consistently
overestimated E. grandis yields and underestimated E. robusta
yields. These over- and underestimates were due, in part, to species
differences in tree heights, and therefore to tree stem forms, and to
the compensating effect of the differences in wood and bark specific
gravities.
Because more complex models resulted in little meaningful im-
provement in predicting, the models summarized in Table 1 are
appropriate for estimating biomass and energy contents of each spe-
cies. Oven-dry stem wood and bark biomass values, as derived from
the equations in Table 1, are presented in Tables 2 and 3 to describe
the range of tree sizes actually sampled. Predicted tree energy con-
tents on a dry weight basis are shown in Tables 4 and 5. To derive the
equivalent energy value of a eucalypt in terms of metric tons of coal,
the entries in Tables 4 and 5 may be divided by the specific energy
value, given in megajoules (Mj)? If a particular coal had an energy
content of 0.03024 Mj/g, for example, an E. grandis tree weighing
97.7 kg dry would be equivalent to 0.0613 metric tons of coal.
Equations for converting among the different contents are also
presented in Table 1. Relationships among the variables were essen-
tially linear, and several intercepts were near zero. On a dry weight
basis, the moisture contents averaged 114% and 90% for E. grandis
and E. robusta, respectively. Energy content can be derived from
oven-dry biomass, on the average, by multiplying by 0.01877 Mj/g for
E. grandis and 0.01965 Mj/g for E. robusta.
These equations contribute to the estimation of biomass and en-
ergy contents of large eucalypts in south Florida. Factors which may
influence their application to particular cases are genetic origin of
trees, size and location of trees, and cold damage. Due to tree im-
provement efforts in south Florida, more recently planted stands may

1. Joules x 106 (One megajoule is approximately 950 BTU; see the conver-
sion table at the end of the bulletin.)










Table 1. Predictive equations for deriving biomass and energy contents from 11-year-old Eucalyptus grandis and E. robusta
tree parameters and for converting among biomass and energy contents.

E. grandis E. robusta
Independent-Dependent
Variables bo bl R2 SE bo bl R2 SE

DBH2 H
Green biomass (kg) 35.8 .0284 .97 34.7 64.9 .0206 .91 41.2
Oven-dry biomass (kg) 13.5 .0134 .98 15.2 22.2 .0115 .95 22.5
Energy (Mj) 225.7 .2512 .97 302.3 397.7 .2273 .95 418.3

Green biomass
Oven-dry biomass (kg) -0.4 .468 .99 10.9 -7.3 .526 .99 7.3
Energy (Mj) -36.4 8.784 .99 219.8 -196.8 10.446 .99 134.8

Oven-dry biomass
Energy (Mj) -30.1 18.774 .99 27.76 -31.0 19.649 .99 35.6

R2 = coefficient of determination
SE = standard error








Table 2. Predicted oven-dry biomass (kg) in the lower 75% of stem wood
and bark of bole of 11-year-old Eucalyptus grandis.


Total Tree Height (meters)
14 16 18 20 22


36.9
43.4 47.1
54.2 59.3
66.7 73.4
89.3
107.1
126.7
148.2
171.6


50.9
64.4
80.0
97.7
117.5
139.3
163.2
189.2
217.3
247.5


69.5
86.7
106.1
127.9
151.9
178.2
206.8
237.7
270.9
306.3


24 26


164.5
193.2
224.4
258.1
294.3
332.9


177.0
208.1
241.9
278.4
317.7


Table 3. Predicted oven-dry biomass (kg) in the lower
and bark of 11-year-old Eucalyptus robusta.


75% of stem wood


Total Tree Height (meters)
14 16 18 20 22


44.4 47.6 50.7
52.4 56.7 61.0
67.3 72.9
79.2 86.4
101.4
118.0
136.3
156.1
177.4


65.3
78.5
93.5
110.2
128.7
148.9 161.6
170.9 185.8
194.7 211.9 229.2
220.2 240.0 259.8 299.6
247.5 270.0 292.5 315.1
302.0 327.4 352.8


have different form factors than the ones observed in our sampling.
As with any predictive equations, these are strictly relevant only to
the range of independent variables observed, namely 10 to 34 cm
DBH and 14 to 26 m in height. Similarly, eucalypts growing in
locations differing from the study site may deviate from the rela-
tionships we observed. Dieback from frost damage such as occurred in
January 1982 must be strongly considered in the use of these equa-
tions. Large trees, which typically survive cold weather but have


24 26







Table 4. Predicted oven-dry energy content (megajoules) in the lower 75%
of stem wood and bark of 11-year-old Eucalyptus grandis.


Total Tree Height (meters)
14 16 18 20 22


805
1014
1255


678
877
1112
1383
1691
2034
2414
2830
3282


949
1210
1512
1853
2235
2657
3120
3622
4165
4747


1309
1640
2016
2436
2901
3409
3962
4559
5200
5885


24 26


3144
3699
4302
4953
5652
6400


3387
3988
4641
5347
6104


Table 5. Predicted oven-dry energy content (megajoules) in the lower 75%
of stem wood and bark of 11-year-old Eucalyptus robusta.


Total Tree Height (meters)
14 16 18 20 22


853 919
1018 1107
1324
1570


983
1082
1439
1716
2026
2367
2742
3148
3588


1284
1555
1862
2206
2586
3002
3454
3943
4467
5028


3263
3760
4297
4874
5491
6147


24 26


4652
5281
5954
6670


5688
6417
7193


stem dieback to about a 5 cm diameter, are likely to have a
height-DBH relationship varying from that of the sample trees,
which had encountered only minimal frost damage at the time of the
study.

APPLICATION
Prediction of green biomass, dry biomass, or energy content of
E. grandis or E. robusta trees can be accomplished by use of the
equations in Table 1. For example, the oven-dry biomass in the lower







75% of the stem of an E. grandis that is 20 cm in DBH and 22 m in
height is estimated as:
kg = 13.5 + 0.013 (202) 22 = 127.9

For the two species, energy yield can be estimated from known
green or dry biomass and dry biomass derived from known green
biomass by use of the equations in Table 1. To demonstrate, for an
E. grandis that has a green biomass of 361 kg, the estimated energy
yield of the tree is:
megajoules = 36.4 + 8.784* 361 = 3135

and the equivalent dry biomass is:
kg = -0.4 + 0.468 361 = 168.5


LITERATURE CITED
Clark, III, A. and J. G. Schroeder. 1977. Biomass of yellow-poplar in natural
stands in western North Carolina. USDA For. Serv. Res. Pap. SE-165.
41 pp.
Hitchcock, III, H. C. 1978. Aboveground tree weight equations for hardwood
seedlings and saplings. TAPPI 61(10):119-120.
McClure, J. P., J. R. Saucier, and R. C. Biesterfeldt. 1981. Biomass in
southeastern forests. USDA For. Serv. Res. Pap. SE-227. 38 pp.
Phillips, D. R. 1977. Total tree weights and volumes for understory hard-
woods. TAPPI 60(6):68-71.
Rockwood, D. L., L. F. Conde, and R. H. Brendemuehl. 1980. Biomass pro-
duction of closely spaced Choctawhatchee sand pines. USDA For. Serv.
Res. Note SE-293. 6 pp.
Roeder, K. R. 1981. Variation in energy-related traits of Eucalyptus in South
Florida. M.S. Thesis, Univ. of Florida, Gainesville. 73 pp.

UNIT EQUIVALENTS
1 cm = 2.54 in.
1 m = 3.28 ft.
1 kg = 2.20 lb.
1 metric ton = 1.10 ton
1 joule = 4.1868 calories
1 megajoule = 947.8 BTU
1 joule/g = 0.4299 BTU/lb.







































This public document was promulgated at an annual cost of
$620 or a cost of 310 per copy to provide information on predict-
ing stem biomass and energy content yields of two species of
eucalyptus.


All programs and related activities sponsored or assisted by the Florida
Agricultural Experiment Stations are open to all persons regardless of race,
color, national origin, age, sex, or handicap.



ISSN 0096-607X


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