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- YALE UNIVERSITY • SCHOOL OF FORESTRY
BULLETIN No. 7
A PROGRESS REPORT OF
THE RESULTS SECURED IN TREATING
PURE WHITE PINE STANDS
ON EXPERIMENTAL PLOTS AT
KEENE, NEW HAMPSHIRE
BY
RALPH C. HAWLEY
Professor of Forestry, and Forester in Charge of the School Forests
NEW HAVEN
Yale University Press
1922
YALE UNIVERSITY • SCHOOL OF FORESTRY
BULLETIN NO. 7
YALE UNIVERSITY • SCHOOL OF FORESTRY
BULLETIN No. -
A PROGRESS REPORT OF
THE RESULTS SECURED IN TREATING
PURE WHITE PINE STANDS
ON EXPERIMENTAL PLOTS AT
KEENE, NEW HAMPSHIRE
BY
RALPH C. HAWLEY
Professor of Forestry, and Forester in Charge of the School Forests
NEW HAVEN
Yale University Press
1922
^■^;t^-
c:*
CONTENTS
Location of the Plots
Character of the soil
Page
Purpose of the Report c
5
5
The site quality 6
Classification of the Plots lO
The Thinning Experiments lO
Description of the experiments lo
Tables of statistical data compiled from the measurements
taken on the thinned and unthinned plots 14-22
Summary of results 22
The Experiments in Reproducing White Pine under the
Shelterwood Method 29
A PROGRESS REPORT OF
THE RESULTS SECURED IN TREATING
PURE WHITE PINE STANDS
ON EXPERIMENTAL PLOTS AT
KEENE, NEW HAMPSHIRE
PURPOSE OF THE REPORT
IN October, 1905, nineteen permanent sample plots were established in
the white pine type near Keene, New Hampshire, by the United States
Forest Service in cooperation with the Faulkner and Colony Manufacturing
Company on lands owned by the latter. The plots were remeasured in 1909
and again in 191 5 by representatives of the United States Forest Service.
After the 19 15 measurement the plots were turned over to the Yale School of
Forestry. In September, 1920, the plots were remeasured for the third time,
three additional plots were established and six of the original plots were dis-
continued. Fifteen years have elapsed since the beginning of the experi-
ments. While the experiments are only partly completed, information of value
in reference to the management of white pine has been acquired. The pur-
pose of this publication is to make the information available for foresters
and landowners engaged in managing white pine lands.
LOCATION OF THE PLOTS
Keene, New Hampshire, is located in Cheshire County in the south-
eastern part of the state, approximately 16 miles north of the Massachusetts
state line and 13 miles east from the Connecticut River. It is an important
New England center of the white pine box and woodworking industries.
The area is within the New England white pine region.
Character of the soil. — Within the New England white pine region at
least two distinct classes of upland (or well-drained) sites can be dis-
tinguished. One consists of the heavier, more fertile soils, the other com-
prises the lighter, sandier, and more sterile soils. Pure stands of second
growth white pine are found on both classes of site, principally on areas
cleared for pasture or cultivation and later allowed to grow up to forest.
Upon the heavier, more fertile soils the pine meets severe competition from
many hardwoods, several of them faster growing in height and more shade
PURE WHITE PINE STANDS
enduring than the white pine. On the lighter, sandier soils fewer hardwoods
compete with the pine, and those which do, offer a weaker competition
against the white pine than do the same species on the more fertile soils. This
difference in character of competition between the pine and hardwoods has
important bearing upon the management of the white pine type. Treatment
which may be successful upon one class of site will not necessarily be satis-
factory upon the other.
The Keene plots are located upon the river plain of the Ashuelot about
50 feet above the level of the river. The soil is a fine, deep sand, droughty
in summer. Although level and free from stones the land is considered rather
light for agricultural use.
The area may be considered as typical of the second class of upland sites,
just described, upon which hardwood competition with pine is weak.
Hence the information contained in this report is applicable primarily
to this class of upland sites. It should apply to such sites where found
throughout the New England white pine region.
The site quality. — ^The site may be further classified as lying between
Quality II and Quality III and closest to the latter.
This statement is based on comparison of values secured in the unthinned
plot, number 604, with corresponding values given in the best existing
yield table for white pine.^ Table i shows the comparison.
The average heights of dominant trees, total basal areas and volumes in
cubic feet, computed for the years 1905, 1909, 191 5, and 1920 when the
stand was successively 35, 39, 45, and 50 years of age, have been compared
to corresponding values for Quality II and III sites taken from the yield
table.
Height was assumed to be the best criterion of site quality, hence this
factor was used first in comparing plot 604 with the yield table.
The results of this comparison show that in 1905, when 35 years of age,
plot 604 had an average height four per cent above Quality II site values ;
in 1909, at the age of 39 years, its height was less than one per cent above the
Quality II values; in 191 5, when 45 years old, the height was midway
between Quality II and III ; and in 1920, at the age of 50 years, the height
was about three per cent above the Quality III site values in the yield table.
If the figures are taken literally the plot has changed during the 1 5 year
period from site II to site III. This anomalous situation must be due to
discrepancies in the data. Since plot 604 has remained unthinned the
^ White Pine under Forest Management, by E. H. Frothingham, Bull. 13, United
States Department of Agriculture, pp. 21 to 23.
Volume in cubic
O
O
O
o
feet
-*•
•4-
0^ ?" Basal area in
T*-
■^
Sv
O H
Ov
o
,K
£ ;3 sq.feet
N
c
2
J D Average height
CO
o
15
< 5 of dominant
^ rj /r/ feet
00
L/S
^
■Sk
Q J I
«r
►J o
>• f-c r Volume in cubic
o
00
O
o
o
o
O
1
in cubic feet on
' pine yield tab.
s: ^ ^
w S ^ Basal area in
1 H :3 .^./../
'^ ^ <3
^ >-< D Average height
w g of dominant
[-, > /"/v^/ in feet
<5
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N
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lo
PURE WHITE PINE STANDS
figures, upon which "average heights of dominant trees" are based, had to
be secured from hypsometer measurements of standing trees. There may be
small errors made in securing the average height of dominant trees under
this method but hardly enough to affect the comparison.
Basal area and volume as factors for measuring quality of site usually
are considered less reliable than height, because the total basal area or
volume depends upon the density of stocking as well as upon the quality of
site. It is only in fully stocked stands or in those whose per cent of stocking,
as compared to the fully stocked, is known that either basal area or volume
can be employed to fix site quality.
When once the quality of site is determined for a given plot the basal
area may be used as an indicator of the degree to which the plot is fully
stocked.
Taking the height as the indicator of site class and basal area as indicator
of degree of stocking the following result is secured when comparing plot
604 with the yield table already used. In securing these figures interpola-
tion has been made between printed values in the yield table.
Plot 604
Was at age
Stocked
in fer cent of a
in years
fully stocked stand
35
82
39
85
45
90
50
93
In order to check with the yield table the volumes in cubic feet actually
measured on the plot at the different ages should be only those proportions
of the volumes in the yield table which the basal areas bear to the basal
areas of a fully stocked stand. Compared in this way the actual volumes
show only slight differences as indicated below from those in the yield table.
THE ACTUAL CUBIC FOOT VOLUMES ON PLOT 604
At age in
Differ from the volumes in
years
the yield table by only
35
6 per cent
39
2 " "
45
2 " "
50
2 " "
In conclusion, height, basal area, and volume as actually measured on
plot 604 at intervals for the last fifteen years are in harmony with one
8
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PURE WHITE PINE STANDS
another and when one is secured from the yield table the others will be
found to check closely. But, during the 15 year period the three sets of
values run across the yield table from the Quality II to the Quality III
columns.
Judging then from the course of development of plot 604 over a 1 5 year
period it would seem that the values in the yield table at different ages and
on different qualities of site are not in complete harmony with the natural
development of pine stands.
CLASSIFICATION OF THE PLOTS
The permanent sample plots are arranged as follows in two series:
A series to show the results of thinnings ; consisting of main plots
numbered 601, 602, 603, and 604 ranging in size from 0.25 to 0.5 acres and
reproduction plots 601 -A, 602-A, and 604- A, each one square rod in area.
A series to show the results of reproducing white pine under shelter-
wood (the shelterwood method) consisting of main plots Nos. 605, 612,
and 614, ranging in size from 0.25 acre to 0.5 acre and reproduction plots
Nos. 606-610, 613, and 615-619, covering one square rod each.
THE THINNING EXPERIMENTS
Description of the experiments. — The purpose is to bring out the differ-
ences in growth and development resulting from different methods of
thinning as compared to unthinned stands. Four plots were established in
1905 in the pure white pine type on a level, sandy area of uniform site
quality and with fairly uniform density of stocking and silvicultural
condition. The location of the plots with reference to each other is shown
on the accompanying diagram.
The relative condition of the four plots at the time of establishment may
be judged from the data in Table 2. The small range between the plots
in basal area and cubic contents is particularly significant as indicating
their similarity.
Table 3 indicates the treatment given the sample plots after their estab-
lishment in 1905. It will be noted that plots 601 and 602 have been thinned
in the same manner each time; the former with a moderately heavy (C
grade) thinning and the latter with a light (B grade) thinning. A direct
comparison is thus afforded between light and moderately heavy thin-
nings.
10
Plato 66\ to 604
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12
PURE WHITE PINE STANDS
Plot 603 received in 1905 a heavy selection thinning (Borggreve's
method). A number of relatively poorly formed and large crowned domi-
nant trees were removed. To partially cover the openings created by this
cutting most of the intermediate and overtopped trees were left standing.
Unfortunately the presence of these trees made the removal of the large
dominant trees a difficult task. In the logging many of the unmarked lower
class trees were destroyed. After the cutting gaps were left, where the large
trees stood, which have not closed in the succeeding fifteen years. In 19 15
it was decided that to continue thinning among the biggest, dominant trees
(Borggreve's method) was unwise, since the portions of the plot from which
dominant trees had been taken in 1905 still showed wide gaps in the crown
cover, while other portions of the plot were too densely stocked. Many inter-
mediate and overtopped trees were in poor condition. The method of thinning
was therefore changed in 191 5. In that year and in 1920 plot 603 received
C grade thinnings.
A comparison can eventually be drawn between plots 601 and 603 to
indicate the results of C grade thinnings when applied with and without a
first thinning according to Borggreve's method.
Plot 604 from which no trees have been cut serves as a basis for com-
parison with the plots which have received thinnings.
On all plots the slash resulting from each thinning, after close utilization
of merchantable material, has been left on the ground to decay.
Tables 4 to 12 inclusive show the results so far secured as indicated by
the measurements in 1909, 191 5, and 1920. The numbers at the head of
the columns progress consecutively through all these tables in order to make
easy descriptive reference to any column.
Results for the period 1905 to 1909 are less reliable than for the periods
1910 to 1915 and 19 16 to 1920 and should be given small weight in
drawing conclusions. The reason for this is that many unmarked trees
were cut or destroyed by the lumbermen in making the thinnings in 1905
without an adequate record being kept of such losses to the unmarked stand.
For further explanation see page 23.
13
PURE WHITE PINE STANDS
Tables'^ of statistical data compiled from the m,easurements taken on
the thinned a?id unthinned -plots.
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17
TABLE 8.
Mean annual and periodic annual growth per acre
in cubic feet in thinned and unthinned stands.
32 33 34 35
^ Growth in cubic feet
Ti/r 1 , Periodic annual .
Mean annual f ^
Plot through the 1 906 to igio to igi6 to
number year 1905 1909 J9'5 1920
18
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21
TABLE 12.
Average height of the dominant trees in feet
in thinned and unthinned stands.
Plot
number
57 58 59 60
-Average height of do7ni7ia?it trees in feet iti^-
1905 1909 i9'5 1920
601
46
50
54-7
59-7
602
45.8
49-7
54-7
60.2
603
46
48.3
53
57-7
604
46-3
50.5
53-4
55.8
* Secured by averaging the heights, taken from height curves
for each diameter, of all the dominant trees. The height curves
used were constructed partly from measurements of the total
heights of trees cut on the plots in thinnings, but principally from
fiypsometer measurements of trees standing on the plots.
Summary of results. — The experiments must continue one to two decades
longer before final conclusions can be drawn. Careful study of the figures in
these tables should indicate the general effects of the thinnings. Tentative
conclusions based on the data now on hand are presented in the following
paragraphs.
PURE WHITE PINE STANDS
1 . The thimiings have reduced the number of trees per acre by percentages
of the original numbers ranging from 67 to yy. During the 15 year period
from 1905 to 1920 the number of trees per acre on the plot thinned C grade
has dropped 74 per cent ; on the plot thinned B grade 6y per cent ; on the plot
first thinned according to Borggreve's method yy per cent. The decrease
on the unthinned plot due solely to natural causes amounts to only 28 per
cent.
Starting with 778 to 1,032 trees per acre in 1905 the thinned plots (601,
602, and 603) now contain 202 to 308 trees per acre. The number of trees
on the check plot (604) has been reduced by natural causes from 828 to 600.
See Table 4.
A comparison of columns 2 and 3 for plots 601, 602, and 603 would
seem to indicate a large decrease from natural causes between 1905 and
1909. Most of this decrease is accounted for by injuries to unmarked trees
caused by the lumbermen in making the 1905 thinning. The figures in
column 2 were compiled before the thinning from tally of the trees to be
left rather than from an actual count of the trees left standing by the lumber-
men. Many small trees were destroyed.
2. The reduction in number of trees per acre has concentrated growth on
fewer stems of larger average diameter and volume. See Tables 4, 10,
and II.
This is especially noticeable as a result of the C grade thinnings on plot
601. To illustrate the point the respective values in columns 43, 49, 50, and
56 for plots 601 and 604 are presented side by side.
Plot
Column 601 604
43 Diameter of average tree in inches in 1905
before thinning 6.1 6.0
49 Diameter of average tree in inches in 1920
after thinning 9.7 y.y
Increase in diameter of average tree in
inches during the 15 year period 3.6 1.7
50 Average volume per tree in board feet in
1905 before thinning 20.9 18.7
56 Average volume per tree in board feet in
1920 after thinning 77.8 41.8
Increase in volume per tree in board feet
during the 15 year period 56.9 23.1
23
PURE WHITE PINE STANDS
The advantage is obvious. Fewer but bigger trees on the area tend to
lower logging costs and permit the manufacture of larger sized and often
better quality material.
3. Height growth has been stimulated as a result of the thinnings. See
Table 12.
Starting in 1905 with approximately the same average height of dominant
trees (column 57), the three thinned plots now have higher values than the
check plot (column 60).
The C and B grades of thinning (represented by plots 601 and 602) as
yet show little variation in height growth, but are both ahead of the
Borggreve thinning (plot 603). This is brought out in the following table:
Table 13.
Showing the effect of thinning upon height growth.
-Average height of dominant trees-
Height growth for period 1905-20
in feet in percentages
( Co/timn 57) ( Column 60) based on growth on
Plot in 1905 in igzo check plot taJien
number feet feet as 100
601 46 59.7 13.7 144
602 45-8 60.2 14.4 152
603 46 57.7 II. 7 123
604 46.3 55.8 9.5 100
These figures indicate that height growth may be influenced by the
silvicultural treatment of the stand. As a consequence, within the same site
class different standards of height growth may have to be recognized.
4. The actual amounts removed in each of the thinnings are show?i for
each plot in board feet, cubic feet, afid on a percentage basis i?i Table 14.
It will be seen that the plot thinned C grade (plot 601) and the one
thinned in 1905 according to Borggreve's method (plot 603) and sub-
sequently C grade, are close together in the total amounts removed ; though
differing as to the percentages taken out in the individual thinnings.
The 1905 thinning on plots 601 and 603 furnishes a good illustration of
the difference between the C grade and Borggreve style of thinning.
24
1 ^ -S
1 2^^-? s^
Cubic feet
N
NO
00 N
N ON
00 NO
^
^
Co
mo tin
move
inn in
^ NO
— N
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00
N
S
s
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1 -^5 ^^
Board feet
ON
0"
■Kk
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Percentage
"^
of total
LTN
l^ ^
^
volume
g
-5
Amt. per
00
-f N
c
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acre
«
.
^
^
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r X
Percentage
hH
■^
of total
NO
~
<
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^
volume
tJ- t1-
5^
c3
Amt. per
acre
Percentage
of total
volume
N
NO NO
00 U-N
r^ —
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w.
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Amt. per
NO
N N
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I
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r r
Percentage
s
^
of total
volume
H
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^
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r<-i
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^
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^
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r "^
of total
iy-\
NO L'N
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volume
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Ci
cq
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NO
N NO
On "-^
^
^
s-
I L
acre
N
r^ N
LO
Plot no.
NO
NO NO
2.;
PURE WHITE PINE STANDS
The former removed 15 per cent of the board foot contents of the stand
or 20 per cent of the cubic contents, while the Borggreve cutting took out
35 per cent of the board foot volume but only 25 per cent of the cubic
contents. The large percentage of the board foot volume cut is due to the
removal of the largest trees which yielded a relatively high content in board
feet as contrasted to cubic feet, whereas many of the smaller trees cut in
the C grade thinning gave no yield at all in board feet.
The B grade thinnings (plot 602) produced approximately half the
volume of the other cuttings.
5. The basal area fer acre is considered one of the best indicators of the
character of the thinning. Ultimately a standard basal area per acre can be
established for each degree of thinning. After and as a result of each thin-
ning the basal area fer acre would be reduced to this standard.
So far in this experiment no special effort has been made to bring the
basal areas to any fixed standard. The basis for selection of the trees has
been the crown relations and relative thrift of the individual trees. Inspec-
tion of Table 9, particularly columns 40 and 42, indicates that after each
of the last two thinnings the basal area of plot 601 (thinned C grade) has
been brought down to approximately 100 square feet, while that of plot
602 (thinned B grade) has been reduced to 125 square feet.
In future thinnings on the plots these standards will be used.
A record of the changes in basal area per acre since 1905 is given in
Table 9. The discrepancies between corresponding values in columns 37
and 38 are due to the same cause explained under Conclusion i, page 23.
6. The annual growth fer acre exfressed either in board feet or cubic
feet has been increased as a result of the thinnings. Plots 601, 602, and 603,
as contrasted to plot 604 indicate this. See Tables 6 and 8.
Results during the first four years after the experiment was started
(1906 to 1909) contradict the above statement. See Columns 19 and 33.
There may be two reasons for this. First, it may be possible that the bene-
ficial effect of thinning is not always apparent for a few seasons in a stand
previously closed. Second and most important in this instance, the large
decrease in number of trees on plots 601, 602, and 603 between 1905 and
1909, resulting from injuries to unmarked trees caused by the lumbermen
in making the 1905 thinning, greatly reduces or in the case of growth in
cubic feet on plot 602 (column 33) completely offsets the growth during
the period 1906 to 1909.
The periods i9ioto 1915 and 1916 to 1920 each show large increases in
26 '
PURE WHITE PINE STANDS
rate of growth on the thinned plots in both board and cubic feet. (See
columns 20, 21, 34, and 35.) As is well recognized measurement in cubic
feet affords a better expression of the relative wood producing power of
the different stands than does the board foot unit. Consequently the values
in columns 34 and 35 are particularly impressive, as indicating the effect
of thinning on rate of growth.
The slackening of growth in the unthinned plot (604) is striking as
contrasted to the increase in plots 601, 602, and 603.
7. WiiA a wood capital smaller tha?i in the unthinned stand, a thinned
plot gives a higher rate of increase on the invested capital.
It was shown under the preceding caption that the amount of material
actually produced per acre per year was increased. Since the thinnings tend
to reduce the total amount of wood capital remaining in the stand at any
given age as contrasted to the unthinned stand, it follows that the rate of
increase on invested wood capital should in theory be higher in thinned
stands.
This theory is borne out by the results of the experiment as shown in
Table 15.
TABLE 15.
Showing the per cent of increase on invested wood capital
in thinned and unthinned stands.
Per cent of increase on wood capital present at
beginning of period
f 19 10 to \<)\ 5 ^ f 1 916 to 1920
Plot Treatment Capital and increase reckoned in terms of
number Board feet Cubic feet Board feet Cubic feet
601 Thinned 32 24 26 25
602 " 29 26 23 20
603 " 42 20 29 25
604 Unthinned 16 8 13 6
Table 15 has been compiled from the figures in Tables 5 and 7. The
period 1906 to 1909 was not considered because of the inaccuracy of the
27
PURE WHITE PINE STANDS
data relating to the thinned plots after the 1905 thinning. For further
explanation see page 23.
The per cent of increase on invested wood capital is from two to four
times greater in thinned as compared to unthinned stands. The use of
thinnings thus affords not only an opportunity for reduction of the capital
invested in the timber, but at the same time increases the amount of growth
and its per cent in relation to wood capital.
8. The decrease in wood capital resulting from thinnings would be of
importance in lessening taxable values. If the volumes in board feet on the
unthinned plot at any given time are taken as 100, then the volumes on the
thinned plots at the same time are in the following ratio. (Computed from
data in Table 5.)
Volumes expressed as a proportion of the volume of
the utithinned plot assumed as 1 00
After thinning in 191 5 After thinning in 1920
61 63
65 67
50 54
100 100
Thus the wood capital invested in the thinned stand ranges from 50 to
67 per cent of that in the unthinned stand and ought to carry a correspond-
ingly lower valuation.
9. The comparatively early financial return secured from sale of material
removed in thinnings has a most favorable effect upon reducing the cost of
growing a crop of timber as compared to the imtlmmed stand. This relation
is too well understood to require further elaboration here.
10. The thinned plots are in more vigorous and healthier condition than
the unthinned plot. This is evidenced by the relatively large number
of dead and dying trees in the various plots. Very few dead or dying trees
are found in the thinned plots and nearly all the standing trees have op-
portunity to expand their crowns. In the unthinned plot the large number of
living trees prevents even the best dominant trees in the stand from securing
adequate room for crown expansion.
1 1 . Pine reproduction, mixed with some hardwood becomes permanently
established^ as a result of heavy thinnings. In 1905 when the plots were first
established and for a number of years thereafter no figures were taken as
respects reproduction. Recently such records have been started, but the
28
Plot
7 iJ '977 nfif
Treatment
601
Thinned
602
€<
603
<<
604
Unthinned
PURE WHITE PINE STANDS
results so far secured do not warrant more than the statement given above.
Reproduction starting too early in a rotation may readily become a nui-
sance and be something to prevent rather than to encourage. How heavy
thinnings can be used and still keep out reproduction remains yet to be
determined.
12. Weighing all factors the C grade thinning is considered superior to
the B grade or Borggreve thinning. An inspection of the three thinned plots
is of value in reaching this conclusion. The appearance of the stand, and the
character and spacing of the individual trees points to the relative desira-
bility of the C grade thinning.
THE EXPERIMENTS IN REPRODUCING WHITE PINE
UNDER THE SHELTERWOOD METHOD
As stated on page lo three main plots and eleven reproduction plots are
included in the series. These may be further subdivided into three groups
consisting of :
a. Main plot 605 and reproduction plots 606, 607, 608, 609, and 610,
illustrating the final stages of the shelterwood method.
b. Main plots 612 and 614 and reproduction plots 613 and 615 illus-
trating the early stages of the shelterwood method.
c. Reproduction plots 616, 617, 618, and 619 established to show repro-
duction following shelterwood cuttings, but about which insufficient data
were secured at time of establishment to make the plots instructive.
This report will deal primarily with Group a.
Plot 605 of one-half acre in size was established in 1905 in a stand of
close-grown pine, which had been lightly thinned in 1900 by the Faulkner
and Colony Manufacturing Company, and so heavily thinned by the same
company in 1904, as to leave the crowns of the trees barely touching or in
the widest gaps 10 feet apart. Following the cuttings an abundant repro-
duction started under the shelter of the remaining timber. Enough survived
the final cuttings to fully stock the area.
The plot was remeasured in 1909. In the winter of 191 2-1 3 the stand
was cut clear.
At the time of the first thinning in 1900 the age of the stand was 48 years.
No detailed reports are available to show what was removed at each
cutting, further than to indicate that the shelterwood method of repro-
duction was employed.
To trace the development of the reproduction resulting from these cut-
29
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31
PURE WHITE PINE STANDS
tings plots 606, 607, 608, 609, and 610 were laid off on or close to plot 605.
The figures secured from these plots are presented in Table 16.
White pine seedlings at the rate of 30,880 per acre were on the ground
when the plot was established in 1905. These seedlings came in after the
first thinning made in 1910 and originated from the heavy seed crop of 1904.
In 1920 of these seedlings 7,200 per acre were still alive and together
with 480 pine seedlings which started from seed crops subsequent to 1904,
formed dense thickets of reproduction averaging 7 to 9 feet in height with
some individuals as high as 15 feet.
The causes which resulted in this large decrease in number of seedlings
during the fifteen years from 1905 to 1920 can only be surmised, as detailed
records of the seedlings which died were not kept in the early stages of the
experiments. It seems likely that the beetle Hylobius^ Pales, known to be in
the region, was instrumental in reducing the number of seedlings.
A small amount of hardwood reproduction came in with the pine. In 1905
other reproduction than pine totaled 416 per acre. In 1920, 352 hardwoods
(including a few hemlock) per acre, principally birch and cherry, were
present.
At the time of each remeasurement the hardwoods which were overtop-
ping pine were cut back to the ground. Very little of this work was needed.
Now the pine is free. Hardwood competition with pine has not been a serious
factor on these plots.
The small amount of hardwood reproduction and its inability to com-
pete strongly with the pine is attributed to the dry, sandy nature of the site.
The pine tops remaining after the various cuttings were left on the
ground as they chanced to fall. Utilization was close and the slash con-
sisted mainly of the pine branches. The effect of this slash in controlling
the local distribution of pine reproduction is marked. A comparison in
Table 16 of plots 608 and 609 will bring out this point.
Plot 608 represented areas having in 1905 the maximum amount of slash.
Plot 609 represented areas having in 1905 the minimum amount of slash
cover. This condition is reflected in the pine reproduction on the two plots.
Plot 609 had the maximum reproduction of pine, 556 seedlings per square
rod, while plot 608 contained only 48 seedlings per square rod.
The following conclusions appear justified from the results secured on
plot 605 and its accompanying reproduction plots.
^The Life History and. Control of the Pales Weevil (Hylobius Pales) by H. B.
Peirson. Harvard Forest, Bulletin No. 3, Petersham, 1921.
32
PURE WHITE PINE STANDS
1 . Pine reproduction can be successfully obtained by cuttings
under the shelterwood method.
2. Hardwood re-production starts in smaller amounts than
pine reproduction but will overtop a portion of the pine seed-
lings. One or two cleanings to free the pine may be necessary, but
should not prove so expensive as on more moist and heavier soils.
3. The slash left after thinnings in white pine stands is not
abundant enough to prevent reproduction stocking the area, but
may lie thick enough over small patches to greatly reduce the
amount of reproduction on such spots.
Printed by the Yale University Press at the
Earl Trumbull Williams Memorial..