o Progress Report Series No. 85
Agricultural Experiment Station
AUBURN UNIVERSITY
December, 1962
E. V. Smith, Director
Auburn, Alabama
EARLY THINNINGS FROM PINE PLANTATIONS
SHERMAN D. WHIPPLE, Associate Forester
LARGE ACREAGES of pine plantations have been
established by many landowners over the past two
decades.
New plantations are continually being estab-
lished while older plantations are ready for cutting.
Some key questions that the landowner must an-
swer are: (1) What original planting spacing will
prove most profitable? (2) What type cutting or
thinning should be followed and when made? and
(3) What financial return will be realized? An-
swers to these questions will vary with 
circum-
stances of particular owners, and all cannot be
covered in a restricted number of tests. Data pre-
sented represent results obtained from tests made
on the Fayette Experiment Forest, of Auburn Uni-
versity Agricultural Experiment Station. Condi-
tions involved are typical Upper Coastal Plain
small acreage plantations.
DESCRIPTION of AREA
The Fayette Forest is in Alabama's Upper
Coastal Plain Region with upland red and yellow
podzolic soils. Areas planted have specific soil
type designations of Ora or Ruston fine sandy
loams or both. Topography is gentle to moderately
sloping. Plots were located on old field areas with
moderate to severe sheet erosion caused by culti-
vation. Based on measurements taken in 1961, site
quality (site index) ranged from 82 to 90 and av-
eraged 85. The Girard form class (taper) on pres-
ent stems averaged 70 on all stands.
Blocks of loblolly pin us tda L.) an 'of
slash pine (Pinus elliotti 1 ~~l p ted
in 1945 at spacings of 6' X 1, ne ngs per
acre) and 5' X 5' (1,600 seedlings per acre). In
1946 another block of slash pine was planted at a
5' X 5' spacing.
Two types of thinnings were tested. These were
selective thinning (individual stem selection) and
row thinning (removal of all trees in one row re-
gardless of size). The 1946 planting of slash pine
was left unthinned.
Initial thinnings from all stands were cut into
farm fence posts, which utilized stems to a mini-
mum of 21/4" d.i.b., at the small end. All subse-
quent cuttings were for pulpwood, with a mini-
mum of 3.6" d.i.b.
The selective system of thinning was applied to
blocks of both loblolly and slash pine planted at
6' X 6' spacings (see table, parts, A and B). First
thinnings were made in 1955. A second thinning
was made in 1958.
The row system of thinning was applied to
blocks of loblolly and blocks of slash pine planted
at both spacings (6' X 6' and 5' X 5'). Initial
cuttings in all row-thinned blocks removed every
4th row. Second cuttings, again by rows, removed
the alternate row leaving half of the original num-
ber of planted trees. The first row thinnings were
made in 1955 on stands of both species that were
planted 6' X 6' (see table, parts C and D). Second
row thinnings were made in 1957. Planted trees
were left at a spacing approximately 6' X 12'. The
~ ~ r I r II I r II r ~ I V ~ L~ r I ~ P ~ r ~ r ~ r I ~ ~
STOCKING, VOLUMES, AND VALUES FROM EARLY THINNINGS OF PLANTED PINES
Year
STAND
1945
1955
1958
1961
Description
A (Loblolly pine-selectively thinned)
Planted 6' X 6'
Sel.-thin. (posts)
Sel.-thin. (pulp)
Residual
Total
Balance
Net earnings per acre per year'
STAND B (Slash pine-Selectively thinned)
1945 Planted 6' X 6'
1955 Sel.-thin. (posts)
1958 Sel.-thin. (pulp)
1961 Residual
Total
Balance
Net earnings per acre per year
STAND
1945
1955
1957
1961
C (Loblolly pine-row thinned)
Planted 6' X 6'
Row-thin. (posts)
Row-thin. (pulp)
Residual
Total
Balance
Net earnings per acre per year
STAND D (Slash pine-row 
thinned)
1945 Planted 6' X 6'
1955 Row-thin. (posts)
1957 Row-thin. (pulp)
1961 Sel.-thin. (pulp)
1961 Residual
Total
Balance
Net earnings per acre per year
STAND E (Loblolly pine-row thinned)
1945 Planted 5' X 5'
1957 Row-thin. (posts)
1961 Row-thin. (pulp)
1961 Residual
Total
Balance
Net earnings per acre per year
Trees
Total 83.6" up
Number Number
1,200
200
260
650
1,200
240
260
1,200
1,200
200
620
1,200
170
570
1,600
?
?
760
550
650
470
460
630
Basal area
total
Sq. ft
21.60
17.14
108.10
146.84
23.35
11.36
125.78
160.49
24.68
34.00
95.27
153.95
20.84
31.79
9.41
92.01
153.55
8.00
8.12
95.75
111.87
Volume
3.6" up
Std. cds.
3.0
2.4
18.67
24.07
3.3
1.6
21.81
26.71
3.2
2.8
18.65
19.65
3.7
2.4
1.6
15.54
23.24
1.6
1.83
12.91
15.81
Debits
1  
Credits
2
Dollars Dollars
23.87
23.87
28.87
28.87
23.87
23.87
23.87
23.87
27.62
27.62
15.30
12.77
91.48
119.55
95.68
4.39
18.22
8.40
106.87
18833.49
109.62
5.02
18.29
16.05
66.89
101.23
77.86
3.55
21.15
13.76
7.84
76.15
118.90
95.03
4.36
8.42
6.37
63.26
78.05
50.43
2.81
STAND
1945
1957
1961
1961
STAND
1946
1961
F (Slash pine-row thinned)
Planted 5' X 5'
Row-thin. (posts)
Row-thin. (pulp)
Residual
Total
Balance
Net earnings per acre per year
G (Slash pine-unthinned)
Planted 5' X 5'
Residual
1,600
720
1,600
1,420
25.87
18.82
480 98.79
148.48
950
Total
Balance
Net earnings per acre per year
Includes planting costs of $11.00/acre for 1,200 trees and $13.00 per
and protection all compunded at 4% interest to 1961.
All credits received prior to 1961 compounded at 
4% to 1961.
' Net earnings are figured as annuity of balance at 4%.
141.15
141.15
5.25
8.2
17.14
25.59
18.07
18.07
27.62
27.65
15.68
83.99
27.62 127.32
99.70
4.57
26.41
26.41
88.54
88.54
62.18
3.10
acre for 1,600 trees plus $0.15 per acre per year taxes
slash pine stands of this group were thinned for a
third time in 1961. For this thinning the selective
system was used. First thinnings in stands of both
species planted at spacings of 5' X 5' were made
in 1957 (see table, parts E and F). A second row
thinning was made in 1961 to remove alternate
rows leaving planted trees at a spacing of 5' X 10'.
Stems were considered large enough at 10 years
from planting for a cutting of merchantable fence
posts from all stands planted at spacings 6' X 6'.
Stems on stands planted 5' X 5' did not reach this
size until age of 12 years. Stumpage value for posts
from selectively thinned stands averaged $4.35 per
cord as compared with $4.50 per cord for stands of
row-thinned posts. Differences in these figures can
be directly related to reduced cost of marking
trees and removal of products from row-thinned
stands in relation to, the costs involved in selec-
tively thinned stands. This difference would have
been greater except that volunteer pines, seeding
in from adjoining areas, increased the number of
stems to be, removed for row thinning above the
original planted spacing. Many volunteers were
less than 3.6" d.b.h. and had little influence on
final cordwood volumes or on basal areas.
Pulpwood cuttings were begun at age 12 years
in row-thinned 6' X 6' stands, whereas row-
thinned 5' X 5' stands were not large enough for
a pulpwood cutting until age 16 years. Pulpwood
stumpage values ranged from $4.75 per cord from
selective thinnings to $4.90 per cord from row thin-
nings. Differences were attributed to reasons
given under post stumpage values. A third thin-.
ning in one of the row-thinned slash pine stands
(stand D in table) was made on the selective
system for the following reasons: (1) Row-thin-
ning at a 90 degree angle to. the original row thin-
nings was impractical because of the irregular
spacing of trees within the plantation rows. (2)
Each aisle was now wide enough for a pulpwood
hauling vehicle to travel, thereby reducing the cost
of removal by the selective method. (3) Trees
were now of the size where selectivity was manda-
tory if maximum quality was desired for future
cuttings. All future cuttings will be planned for
each stand when basal areas average between 110
and 125 sq. ft.
RESULTS
Stocking of trees over 3.6" d.b.h. ranged from
460 to 650 per acre on the thinned stands and 950
per acre on unthinned stand of slash pine.
Total basal area and cordwood volume were
greater on most thinned stands than on unthinned
stand. One exception to this condition was row-
thinned loblolly stand (stand E in table) where
sheet erosion had been severe. Only one thinned
stand was in need of immediate thinning in 1961.
It was selectively thinned slash, (stand B), sup-
porting a basal area of 125.8 square feet. The un-
thinned stand with a basal area of 141.15 sq. ft.
needed thinning. Stand B had an average growth
rate of 1.7 cords per acre per year.
Net earnings, were consistently greater for slash
stands than for loblolly receiving comparable treat-
ments. Selectively thinned slash stands gave a
higher net return ($5.02 per acre per year) than
row-thinned slash stands ($4.36 and $4.57). Selec-
tively-thinned loblolly stands also gave a higher
net return ($4.39 per acre per year) than row-
thinned loblolly stands ($3.55 and $2.13). All
thinned slash pine stands yielded a higher net re-
turn than when left unthinned for 15 years at a
5.' X 5' spacing. Differences in net returns from
original spacing (for the row-thinned loblolly and
slash) were not consistent.