Reproduced from JOURNAL OF FORESTRY,
November
1978,
by the FOREST SERVICE,
of Agriculture,
76,
Vol.
U.S.
No.
11,
Department
for official use.
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Economic Assessment of Intensive Culture Of Short-Rotation
Hardwood Crops
Dietmar W. Rose and DeanS. DeBell
ABSTRACT- Hardwood crops coppiced on 4- and 10-year
cycles at spacings of 4 by 4 feet and 12 by 12 feet, respec­
tively, appear economically feasible, while two-year coppice
rotations do not. Short-rotation culture merits serious con­
sideration and operational testing by industrial/and mana­
gers.
I
nterest in short-rotation coppice crops of woody
species is increasing. This trend is not so much a result
of foreseen shortages in hardwoods-nationally,
hardwood removals are still well below growth
706/JouRNAL oF
FoRESTRY/November 1978
(Westvaco photo of its hardwood plantations on Is­
land #3 on the Mississippi River.) (USDA Forest Service 1973)-but reflect an increased
awareness of the potential economic advantages of
growing wood fiber intensively. The apparent excess
of ha:.:dwood growing stock is largely a biological
surplus rather than an economic one since, under cur­
rent economic conditions, harvest and transportation
are infeasible in many locations. Through concentra­
tion of high yields in relatively small areas close to the
pulp mills, intensive short-rotation culture might re­
move many of the uncertainties connected with fiber
supply from small woodlands and public lands. Wood
fiber produced this way might be cheaper, but would
also require large amounts of capital. Lately, intensive
culture has also received attention for production of
wood for energy (Inman, Salo, and McGurk 1977;
Rose 1977).
Dutrow and Saucier (1976) reassessed the economic
implications of short-rotation systems of coppicing
sycamore-"sycamore silage." They concluded that
only industrial landowners would find production prof­
itable, and that economic feasibility for nonindustrial
landowners would require substantial reductions in
crop establishment costs and increased prices for
wood chips.
We expanded on the analysis of these authors by
including wider spacings and longer rotations and by
assessing a much wider range of production regions
and costs. We also wanted to answer some rather
specific questions: ( 1) What can be paid for land? (2)
How do spacing and rotation length affect prof­
itability? (3) What is the impact of nitrogen fertilizer
costs on profitability? (4) Ho;v does harvesting
technology affect the general feas bility of the system?
By evaluating the above matters, we hope to stimu­
late consideration of short-rotation opportunities by
industrial managers and identify some of the most
cost-sensitive areas for future research and develop­
ment efforts.
Methods
Economic model and input data. - We used the
cost information in table 1. We believe the table gives
realistic estimates of cost ranges across the United
States. The yield figures show the range that can be
expected in short-rotation cultures of species like syc­
amore, cottonwoods and poplars, and alders (Dutrow
and Saucier 1976, Gordon 1975, DeBell 1972, Heilman
et al. 1972). Cost and yield information were inputs for
a cashflow program developed by Rose ( 1976). The
model can be used to calculate common measures of
project performance such as present net worth, inter­
nal rate of return, and payback period. The emphasis
of this study, however, is on break-even requirements
which determine the magnitude of revenues or physi­
cal yields required to cover all direct costs of a
specified management schedule or which will make
present net worth equal to zero.
Break-even requirements can be expressed as
minimum required annual (compounded) revenue
flows or as minimum required average monetary yields
in the years in which harvests are scheduled. The lat­
ter is a simpler and perhaps more useful measure for
comparing management systems, because it is at the
time of harvest that yields are actually realized. It is
calculated as average total costs compounded to the
time of harvest. The minimum required harvest yield
in dry tons per acre is obtained by dividing the re­
quired financial yield with the assumed price per dry
ton.
Basic alternatives tested. - The management alter­
natives that could be devised are obviously much too
numerous to allow complete testing of all combina­
tions. Three are shown here to illustrate the range of
intensive culture philosophies from extremely short
rotations with numerous coppicings to longer rotations
with few coppicings (table 2).
Table 1. Cost, yield, and value data, per acre.1
Type of cost
Average
High
-- Dollars -80
40
20
Land rent
Land preparation
Forest
Pasture
Planting distance ( feet)
2 by 4
4 by 4
6 by 6
12 by 12
Management
Administration (annual)
Fertilization (periodic)
Weeding and protection
(rotation)
Harvesting-hauling
2-year rotation
4-year rotation
1 0-year rotation
Rejuvenation
Regeneration
Rehabilitation
250
55
200
30
300
80
140
85
55
15
125
75
45
10
155
95
65
25
3
75
2
25
4
150
20
10
30
80
160
40
320
160
80
400
800
200
25
40
10
70+ planting
70
80
60
Yield (ovendry tons per acre per year)
Price chip value per ovendry ton
1Adapted from DeBell and Harms
Low
4
2
6
35
15
55
(1976).
Table 2. Three intensive-management alternatives.
Alternative
Activity
Land preparation
Planting
Fertilization
Weed control
Harvesting
Rejuvenation
Regeneration planting
Rehabilitation
Rotation of rootstocks, years
Length of cycle used in
coppicing the rootstocks, years
Number of coppicings per
regeneration cycle
Special assumptions
Rejuvenation costs1
Spacing
Yield
Ill
II
------- Year(s) in which activities take place ----- ---1
1
1
1
1
1
1, 4, and every 4th
1
every 2, beginning in 1st
2
2, 3, 12, 13
every 2
every 4
every 10
11
every 2, beginning in 3rd
every 4, beginning in 5th
11
20
20
20
10
20
20
2
4
10
4
4
low
2 by 4
low
high
4 by 4
low to medium
medium
12 by 12
medium to high
11ncludes fertilization in Alternative II.
November 1978/JOURNAL OF fORESTRY/707
With the number of 2-year coppicings that were as­
sumed feasible for the rootstocks, one regeneration
planting at year 10 was required for Alternative I. This
short-rotation alternative uses close spacings, since
they give the highest yields for extremely short rota­
tions. Wider spacings in longer rotations will catch up
with and exceed the yields of the narrowest spacings
(Ek and Dawson 1976). Four coppicings in each 10­
year regeneration cycle were assumed; yields were
expected to be low, but frequent fertilization would
lessen rejuvenation costs.
Alternative II also assumes four coppicings of the
rootstocks, but length of the cutting cycle was in­
creased to 4 years. Low to medium yields are assumed
with a 4- by 4-foot spacing, but medium yields are
more likely with fertilization.
Alternative III analyzes a 10-year rotation and one
coppicing of the rootstocks. Medium to high yields are
expected with a 12- by 12-foot spacing. Fertilization is
almost as intensive as for Alternative II, but rejuvena­
tion costs are assumed to be lower.
Five measures of performance-break-even yield,
cost per dry ton, present net worth, internal rate of
return, and payback peliod-were calculated at a dis­
count rate of 10 percent. Each management alternative
was evaluated for a 20-year period at the three general
cost levels described in table 1.
Results and Discussion
Table 3 gives results of the analyses. Each alterna­
tive was analyzed under two initial site conditions,
forest or pasture, reflecting differences in need for
preparation. Except for Alternative I, the results of
testing the alternatives under the three general levels
of costs are also presented. For simplicity, chip value
and annual land rent were kept at the average level of
$35 per ovendry ton and $40 per acre. The chip plice
may be above average for some parts of the country.
General Appraisal of the Alternatives
The extreme short-rotation alternative (2- by 4-foot
spacing and biennial harvest) does not seeni feasible
even under the low-cost assumption .. Alternatives II
One-year-old cottonwood cutting on Westvaco' s Island #3.
(Photo by Wildon Roberts, Daily American Republic News­
paper, Poplar Bll{ff, Mo.)
and III appear to offer investment opportunities under
some combinations of costs and yields. Break-even
yield requirements, especially at the low-cost level,
are less than the yields in many intensive culture ex­
periments (Heilman et al. 1972, Steinbeck 1973, Gor­
don 1975).
Alternative II appears more promising than Alterna­
tive III. Given average cost, price, and yield it offers a
rate of return of 14 percent for sites that do not require
initial clearing (11-4). These results, however, should
Table 3. Results of economic analyses of intensive culture alternatives.1
Assumed
levels of2
Alternative
Costs
Yield
L
L
Site
Present net
Required yield Required mean Cost per dry ton of
fiber produced
worth per acre
at each harvest annual growth
-- Dry tons per acre -7.33
3.66
6.24
3.12
10.56
5.28
4.65
9.31
-- - Dollars ---471.87
64.10
-317.33
54.57
92.43
-931.36
-754.08
81.50
Internal rate
of return
Payback
period3
Percent
<0
<0
<0
<0
Years
N
N
N
N
1-1
1-2
1-3
1-4
L
L
M
M
L
L
Forest
Pasture
Forest
Pasture
11-1
11-2
11-3
11-4
11-5
11-6
L
L
M
M
H
H
M
M
M
M
M
M
,Forest
Pasture
Forest
Pasture
Forest
Pasture
13.33
10.92
17.45
14.69
24.22
21.11
3.33
2.73
4.36
3.67
6.05
5.28
29.15
23.88
38.18
32.14
52.98
46.17
171.74
326.28
-93.27
84.00
-527.77
-327.77
16.3
29.2
7.0
14.0
<0
<0
8
4
N
12
N
N
111-1
111-2
111-3
111-4
111-5
111-6
L
L
M
M
H
H
M
M
M
M
M
M
Forest
Pasture
Forest
Pasture
Forest
Pasture
40.63
32.37
57.67
48.19
84.13
73.43
4.06
3.24
5.77
4.82
8.41
7.34
35.55
28.32
50.46
42.16
73.61
64.25
11.87
142.68
-330.31
-153.04
-825.00
-625.00
9.7
14.7
2.8
5.6
<0
<0
N
10
N
N
N
N
·
1A/ternative rate of return was 10 percent; price was $35 per dry ton delivered; rent $40 per acre per year. 2L =low, M=average, H =high (see table 1). 3N ·=no payback within production period; investment was not recovered. 708/JOURNAL OF FORESTRY/November 1978
be tempered with a recognition that Alternative II en­
tails-new and less tried management methods, whereas
procedures and equipment in Alternative III are fairly
conventional in current woodpulp plantation manage­
ment for southern pine and eastern cottonwood.
Moreover, though annual production in densely
spaced coppiced stands was similar to that in 9-year­
old seedling stands for black cottonwood (Heilman et
al. 1972), there are indications that in some species the
mean annual increment may not peak until 5 years or
later (DeBell 1972). In practice, then, yields may be
somewhat higher for the longer rotation.
It is not the purpose of this paper to recommend one
specific alternative, but to explore some of the condi­
tions necessary for intensive silviculture to become
economically feasible. Table 3 gives insight into this
problem for general levels of costs, prices, and yields.
Sensitivity analysis was introduced to explore more
closely the types of conditions that would favor inten­
sive cultures. Sensitivity analysis allows calculation,
for any one or more factors, of the magnitude of
changes required to make an alternative economically
attractive.
The effect of a change in the product price is easy to
calculate, because the required yield at harvest (in
tons) is inversely proportional to price, i.e., an in­
crease in product price will reduce break-even yields.
The absolute effect of any price change on break-even
yields will vary with the magnitude of the yields, i.e.,
the higher the break-even requirement the greater the
absolute impact of the price change. These effects can
be easily calculated, given the price under which
break-even yields were originally determined. For
example, with a price of $25 per dry ton the required
yield at harvest of Alternative I-1 would become 10.26
(break-even yield under old price times the ratio of old
to new price: 7.33 x 35/25). The required financial
yield (the total compounded cost at the time of har­
vest) and cost per dry ton of fiber (cost divided by the
harvest yield) are naturally not influenced by a price
change.
The impact of a price change on present net worth is
obviously equal to the discounted (to the present)
value of the revenue change caused by a price adjust­
ment.
To adjust break-even requirements for a change in a
specific cost assumption, one only has to evaluate the
change in total compounded costs at the time of har­
vest. To facilitate further comparisons, table 4 was
constructed. It shows the magnitude of adjustments in
total compounded costs and tons per acre for impor­
tant types of costs. The corresponding changes in
present net worth are the values of table 4 discounted
by the length of the cutting cycle of the various alterna­
tives.
Because the compounding multipliers are not af­
fected, total compounded costs (or break-even re­
quirements) must change linearly with changes in any
one cost factor if all other factors are held constant. To
evaluate the impact of a $20 per acre change in any
cost factor, one simply multiplies the table values by 2.
It is thus possible to generate break-even yields or
present net worth for any level of a specific cost factor
once one solution (here $10 per acre change) has been
found.
One figure was drawn for each alternative to help in
Table 4. Sensitivity of break-even requirements (dollars
and tons per acre) to a change of $10 per acre in four
costs.1
Alternative
I
II
Ill
I
II
Ill
Annual
cost
First-year
cost2
H arvest-year
cost
Fertilizer
cosP
--- Dollars per acre --21.00
2.24
11.00 10.00
13.31 10.00
4.95
46.41
17.02
159.37
10.00
48.57
-- -Tons per acre-- .29
.60
.06
.31
1.33
.29
.14
.38
4.55
.29
.49
1.39
1AII calculations based on tO-percent discount rate. 2A $10-per-acre change in cost for a second, third, or following year is equal to the value of a first-year cost change discounted 1, 2, etc., years. 31n Alternative II fertilization is scheduled also in the years in which rejuvenation takes place. illustrating sensitivity of break-even yields to specified
changes in cost factors and yield levels (figures 1 to 3)
and to allow further analysis. Along each line repre­
senting one combination of factors only the factor
along the horizontal axis is changing. Any factor com­
bination below a horizontal harvest-yield line would
return at least the alternative rate of return to the in­
vestment. Similar graphs can be produced with any
other cost factor on the horizontal axis, but using the
most critical factors would reveal the most informa­
tion.
Changes in any additional cost factor-be it an an­
nual, periodic, or a one-time cost-can be illustrated in
the same graph because they will result in a parallel
shift of a specific break-even line. Again the shift in the
line is linearly related to the size of the change in the
additional cost factor.
If more than one cost factor is to be changed, the
resulting change in break-even requirements and cor­
responding shift in the. curve can be obtained by sum­
ming the individual impacts of the cost factors in table
4. A $10 per acre reduction of all factors listed in the
table would, therefore, lower the harvest yield re­
quirement for Alternative I by 1.26 tons per acre.
The slope of any line is an indicator of the sensitivity
of break-even growth or yield to the factor on the hori­
zontal axis. Similarly, the magnitude of the shift of a
line due to changes in an additional cost factor is de­
pendent on the sensitivity of break-even requirements
to a cost factor under consideration. In Alternative I,
for example, break-even yields are 2.1 times more sen­
sitive to a $10 per acre change in an annual cost than in
the harvest cost. It should be kept in mind, however,
that a $10 change is not so likely for some cost factors
as it is for others.
Only price changes will cause a change in the slope
of break-even lines, and, therefore, lead to a change in
the sensitivity of break-even yields to all other cost
factors.
The sensitivity of break-even yields to a change in
annual costs obviously increases with the length of the
rotation. Similarly, their sensitivity to any one-time
cost change is greater the earlier this cost occurs in the
production period. In contrast, a change in harvest
costs (or any other cost occurring in the last year of the
harvest cycle) will affect break-even requirements
equally over all alternatives.
November 1978/JOURNAL OF FORESTRY/709
With these general statements in mind, it is now
possible to further analyze previous results. Figure 1
illustrates that Alternative I even at low land rent ($20
per acre) would require yields far above the low levels.
If average yields could be obtained and low overall
costs are assumed, the alternative becomes feasible.
Harvest costs could increase by $23.1 0 per acre before
the alternative becomes infeasible. Unless average
yields (at least 4 ovendry tons per acre annually) can
be consistently attained, substantial changes in current
,......
2!
----.
Ill
c
g
lJI -1
4..c
-
3:
e
nr-2
Ol
(ii
:J
c
c
ro
7.5
15
,.....
()
<ll
en
c
----.
----.
g
g
5
"0
Ol
(ii
::l
c
c
<ll
c
J<ll
I-
.s::.
2.s m
¥
'5
E
cr
Q)
a:
"0
·s
cr
Q)
a:
0
$50
$150
$100
Harvest costs/acre
Figure 1. Sensitivity of required growth and yield for man­
agement Alternative I to changes in han,esting cost and
price.
25
6
li-3
:rr- 4
---- L----$30
$50
Land rent (acre/year)
----
$70
0
Figure 2. Sensitivity of Alternative II to changes in land
rent.
7 10/JOURNAL OF FORESTRY/November 1978
2 ffi
Q)
E
"0
·s
cr
Q)
a:
"0
2!
·::;
.s::.
e
Qj
·;;:.
0
6
0
--
----------
$10
--------
$30
Land rent (acre/year)
--
$50
0
&
Figure 3. Sensitivity of Alternative Ill to changes in land
rent.
culture and harvest technology would be needed to
make this alternative economical. With present
knowledge and experience, Alternative I must be con­
sidered risky. This finding is in contrast with the con­
clusions reached by Bowersox and Ward (1 976),
whose production cost estimates for 2-year coppice
crops of even their least productive clone were less
than half the amounts indicated here. Harvest costs in
their analysis, however, were assumed to be similar to
costs in corn production. We believe costs will be con­
siderably higher for harvesting hardwood coppice.
Figure 2 shows how Alternative II is affected by
land rent, the most important cost factor in this case.
For any ipdicated line all factors except land rent are
held constant. Generally, the alternative looks very
promising under medium cost conditions both for pas­
ture land as well as for forest sites. For the latter (II­
3), rents would have to be $29.10 per acre for eco­
nomic feasibility. Rents below $30 per acre for
forested sites can be expected in many parts of the
country.
Figure 3 for Alternative III is of special interest
because it illustrates the great potential of the alterna­
tive if high yield can be obtained. Most cost factor
combinations fall below the high-yield line and would
imply internal rates of return above the stated alterna­
tive rate of 10 percent. Even on a forest site (III-3) this
alternative appears promising With high yields, be­
qmse rents below $40 per acre are likely for most
forestlands. Under average yield and otherwise aver­
age costs, rents would have to be $1.16 per acre for
forested sites and $22 per acre for pasture to make
Alternatives III-3 and III-4· feasible. Cost reductions
below average levels for more than one factor would,
therefore, be necessary for feasibility of Alternative
III-3.
Consideration of Specific Production Costs
Land cost and preparation. - Because of differ­
ences in site preparation costs (table 3), conversion of
pasture and other marginal agricultural land will usu­
ally appear more promising than conversion of forest­
land. A bias is introduced by looking only at a 20-year
planning horizon, however. The initial cost advantage
of agricultural sites applies only to the first coppice
cycle; site preparation costs would be similar for most
sites when reestablishment becomes necessary.
The results of the sensitivity analysis in table 4 also
give an indication of the trade-off between site prepa­
ration costs and land rent. For Alternative III, a $ 10
per acre change in an annual cost such as rent has over
nine times the importance of a $ 10 change in site prep­
aration costs on break-even requirements in dollars or
tons per acre ( 159. 37/17.02 or 4. 55/0.49). In many situ­
ations, land rents for pasture and forest sites are likely
to differ by $20 per acre or more. Clearing forest sites
for intensive culture, therefore, might be attractive
even at costs of $200 or more per acre.
Harvest. - During the past few years, whole-tree
harvesting systems including scaled-down feller­
bunchers, skidders, and mobile wood chippers have
been developed and are being used for small-log har­
vest in conventional forests. For many sites these sys­
tems provide a seemingly acceptable means for har­
vesting intensively cultured, short-rotation crops.
Compared with data provided by some equipment
manufacturers, the harvesting costs used in our
analyses are high. Only a minor reduction in harvest
costs ($2 1.72 per acre) would be required to make Al­
ternative III-1 economically attractive.
Questions regarding systems and costs of harvest,
especially for very dense spacings and short rotations,
have not been resolved. The need for new technology
is less urgent for the wider spacings and cutting cycles
longer than 10 years. Prototypes of highly mechanized
harvesting systems for short-rotation crops are under
development and may lead to major reductions in har­
vesting costs. Under average cost assumptipns, if har­
vesting costs for Alternative 11-3 were $80 instead of
$ 160 per acre, the required yield might drop by 2. 3 tons
or 13 percent, enough to raise the return to at least 10
percent.
Planting. - Profitability is enhanced substantially
by widening the spacing (e.g. , 2 by 4 feet to 4 by 4 feet
and wider) and lengthening the cutting cycle (2 to 4 or
more years). Earlier analyses and reviews (Dutrow
1971, Smith and DeBell 1973) pointed to the high costs
of establishing dense plantations as a major obstacle to
profitability. Wider spacing costs less (table 1), and the
change in spacing philosophy has also led to other ad­
vantages such as use of conventional equipment for
culture and harvest.
Fertilizer and species.- In the past 2 or 3 years, the
cost of fertilizer has increased markedly in many re­
gions. Fertilization (especially with nitrogen) will un­
doubtedly be an integral part of highly intensive,
short-rotation culture systems. Therefore, we as­
sessed the impact of changes in fertilizer costs on prof­
itability and break-even yields for Alternative II.
If land rent is $40 per acre annually, yields of four
ovendry tons per acre per year on forestland (II-3) will
net a profit if fertilizer costs per application are $36.80
per acre or less. At current fertilizer prices, this
amount would probably be insufficient if 150 to 200
pounds of N per acre are applied and especially if
potassium, phosphorus, or other elements are also
used.
Among the prime candidates for short-rotation man­
agement are species of the genus Alnus (alder), which
fix atmospheric nitrogen. Other factors being at least
equal, differences in fertilizer costs could tip species
considerations in favor of alder.
Implications
The foregoing analysis suggests that intensive cul­
ture of short-rotation hardwood crops is economically
feasible in some situations. Yields needed to break
even under average management conditions and at
chip prices of $35 per ovendry ton have been attained
in trials in the South, Lake States, and Pacific North­
west. Pasture and other marginal agricultural land
probably is available at lease rates of $50 per acre or
less in most areas. Many companies also have forest­
land that is suitable for conversion to short-rotation
culture.
If fiber supply shortages and chip prices of $35 per
ovendry ton are anticipated, companies can consider
short-rotation culture as one means of meeting future
wood needs. The illustrations and relationships and
sensitivity analysis provided in this paper can be
adapted to consider other estimates of costs, price,
and yield. Although only a few of the costs and trade­
offs were examined here, the general indication, based
on wider analysis, suggests that rapid production of
fiber by short-rotation culture can be profitable. In
view of projected fiber shortages, the system merits
serious consideration and probably small-scale, opera­
tional testing by industrial land managers. 1111
Literature Cited
BOWERSOX,
T. W., and W. W. WARD. 1976. Economic analysis of a short­
rotation fiber production system for hybrid poplar.
DEBELL, D.
J.
For. 74:750-753.
S. 1972. Potential productivity of dense, young thickets of alder.
Crown Zellerbach Cent. Res., For. Res. Note 2, 7 p. Camas, Wash.
DEBELL, D.
S., and J. C. HARMS. 1976. Identification of cost factors associ­
ated with intensive culture of short-rotation forest crops. Iowa State
J.
Res. 50:295-300.
DUTROW, G.
F. 1971. Economic implications of silage sycamore. USDA
For. Serv. Res. Pap. S0-60, 9 p.
SAUCIER.
DUTROW, G.
F., and J. R.
1976. Economics of short-rotation syc­
amore. USDA For. Serv. Res. Pap. S0-114, 16 p.
EK, A. F., and
D.
H.
DAWSON.
1976. Actual and projected yields of Populus
"Tristis #1" under intensive culture. Can.
GoRDON, J.
Res. 49(3-pt. 2):267-274.
HEILMAN,
J.
For. Res. 6:132-144.
C. 1975. The productive poiential of woody plants. Iowa State J.
P. E.,
D.
V. PEABODY,
J R., D.
S.
DEBELL,
and R. F. STRAND.
1972. A test of close-spaced, short-rotation culture of black cottonwood
in the Pacific Northwest. Can.
INMAN,
R. E.,
D. J. SALO,
and
B.
J.
I.
For. Res. 2:456-459.
Mc;GuRK.
1977. Silvicultural biomass
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STEINBECK, K. 1973. Short-rotation forestry in the United States: A literature
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USDA
FoREST SERVICE.
1973. The outlook for timber in the United States.
For. Resour. Rep. 20, 367 p. Washington, D.C.
THE AUTHORS- Dietmar W. Rose is associate professor, Col­
lege of Forestry, University of Minnesota, St. Paul. Dean S.
DeBell is principal silviculturist, Pacific Northwest Forest and
Range Experiment Station, USDA Forest Service, Olympia,
Washington.
November 1978/JouRNAL
OF
FoRESTRY/7 1 1