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2

Occasional Paper No. 3*

April 1, 1935

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NORTHEASTERN FOREST EXPERI15ENT STATION

C. Edward Behre, Director
New Haven, Conn,

SUGGESTIONS FOR WEEDING IN NORTHERN HARDWOODS

By

Victor S, Jensen
Associate Silviculturist

*Previous unnumbered papers in this series were entitled;

1 — 1

o

"Forestry Work for Unemployment Relief"
by Victor S. Jensen

February 8, 1933

o

ro

"Northeastern Forest Experiment Station
Surveys its First Ten Years"
by C* Edward Behre

June 15, 1933

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SUGGESTIONS FOR YffiEDING IN NORTHERN HARDl/YOODS

By

Victor S, Jensen

Northeastern Forest Experiroent Station*

The northern hardwood type is one of the most extensive and
commercially one of the most important forest types in the Northeast,
The present poor condition of the stands and recently cut-over areas
in this type is the result of extensive cutting operations in which
the succeeding crops were given no consideration, or if provisions
were made for the succeeding crop the stand did not develop as antic-
ipated# Duo to the large proportion of undesirable trees which
occur on most cut-over areas in this type, a weeding operation is
necessary to secure a desirable stand as this mil increase the pro-
portion of desirable species in a stand, stimulate the growth, and
improve the quality of the residual stand.

Classification of Stems

In any weeding operation the saplings fall in three classes;
crop trees which will be favored in the cultural operation; weed
trees that are retarding the development of the crop trees and
which should be eliminated; and trainers which make up the remainder
of the stand and should remain at least temporarily to crowd the
crop trees from the side and insure a final stand of well formed,
clean boled trees. Men inexperienced in this type of work have a
tendency to select too many trees for cutting that might better Serve
as trainers. The less desirable trees ordinarily classified
as weed species are not necessarily weed trees in this type of
cutting. Position in the stand in relation to the crop tree is
the primary consideration; individual white ash and sugar maple trees
might be cut as weeds while pin cherry and striped maple may serve as
trainers .

Selection of Crop Trees

In selecting the crop trees, there are a number of important
considerations. In northern hardwood stands, the most desirable
species are white ash, sugar maple, paper birch, yellow birch, bass-
wood, black cherry, red spruce, balsam fir, and hemlock. Beech,
red maple, and aspen are less desirable than the ab©ve, altho they'
should be favored in the stand in preference to gray birch, pin
cherry, striped maple, and mountain maple. Single stemmed saplings
should ordinarily be given preference, particularly those of seed
or seedling sprout origin; sprouts from stumps more than 2 inches in
diameter should never be favored as crop trees ^ The prospective

Maintained at New Haven, Connecticut, in cooperation with Yale
University,

crop trees (except tolerant conifers) should he of average or slightly
above average height. Trees less than average height are likely to
have underdeveloped cro'ivns and root systems, and consequently have
difficulty in surviving in competition with the surrounding growth.
Saplings too far above the average height should be eliminated as they
will develop into wolf trees. If available, crop trees should be
selected at 12 to 18 foot intervals; unfortunately desirable saplings
are not always well distributed, a condition v\rhich may be partially
overcome by a closer grouping of the crop trees bordering the poorer
sections of the stand* On some areas a sufficient number of the more
desirable individuals may be developing satisfactorily and an expense
for weeding may not be justified. On other areas the stand in spite
of any practicable treatment will probably have little commercial value,
except possibly, for fuelwood. It is doubtful whether treatment
of areas supporting only such borderline species as beech and red maple
will justify the expense of cultural work.

When to Weed

In order to obtain the best results in northern hardwood stands,
weeding operations should be carefully timed, for if undertaken when
the trees are beginning to assert their dominance and before competition
becomes too keen, the minimum expense will insure the maximum benefits.
I'Teeding should be delayed until there is a differentiation into crown
classes and it is possible to tell which saplings give promise of
the best development; but if weeding is postponed too long some of
the potential crop trees will be underdeveloped or dead as a result
of competition vfith v/eed species and in other cases the differentiation
in heights will be so pronounced that individuals v/hich otherwise
might have made up the final crop must bo cut to prevent their develop-
ment into wolf trees* On good sites weeding operations will neces-
sarily be made at a shorter interval following logging operations
than on the poorer sites. Ordinarily the first weeding should be
made 5 to 10 years after logging; on seme areas a second weeding 5
to 10 years later may be necessary to insure the highest returns* In
order to readily identify the species, weeding in northern hardwood
stands can best be carried on when the foliage is on the trees. If
the v;coding is carried on in late summer the resulting sprout growth
will probably be less vigorous than if carried on in the spring or
early summer months .

Composition and Character of Stands to be Y^eoded

In selecting an area to carry on weeding experiments, the Bart-
lett Exporimental Forest offered an opportunity to work on cut-over
areas of different ages as annual fuelwood sales have been made in
hardwood stands on this tract for the past twenty years* Y'fith the
exception of some of the more recent sales, the areas were marked for
cutting by the local ranger who reserved the softwoods and better hard-
woods* As a result of this marking practice the residual stands on
areas classified as cut-over were very irregular; small areas were
clearcut while on others none of the trees were removed. Table I

-2-

and Figure 1 give an indication of the average stand of reproduction
and '^mailer size classes on 180 acres cut-over from two to twelve
y'jar>; previously and allowed to develop without subsequent treatment.

By comparing conditions in the two age groups in Table I and
Figure 1 it v/ould appear that if the reproduction is allowed to develop
without treatment there is an increase varying from 1 to 18 percent
in the proportion of stems in the four larger size classes, altho
there are about 30 percent fewer stems of all size classes on areas
cut-over from 8 to 12 years before the inventory than on the 3 to 7
year cuttings. As brought out by Tabic I, the proportion of valu-
able species of all the size classes is slightly lov/er in the older
age groups except the ,6” to 1,6” class, which shows a pro-

portionate increase of about 7 percent. If allowed to develop without
cultural treatment, the proportion of valuable species on this area
will probably continue to decrease as the fast growing beech and red
maple sprouts vj-ill eventually dominate the stand. The worthless
species (pin cherry and striped maple) are relatively more important
in tho older age groups, but this is only of minor significance as
they are shortlived and v«rill give way to other species as the stand
develops. In both age groups the valuable species occur in suffi-
cient numbers to justify a weeding operation.

The stands on the Bartlett Experimental Forest are no more
favorable for a v/eeding operc.tion than the average cut-over areas in
northern hardY\rood sta.nds of tho region. A comparison of stands on
areas examined at Bartlett with five areas cut-over from 1927 to 1931
and later examined by A. C. Van Nort and forest rangers on the ■'=;\rhite
Mountain National Forest, vtrould indicate that on the Bartlett Ex-
perimental Forest the proportion of desirable species, particularly
sugar maple, is well below average for the White Mountains.* Beech,
which is not a particularly desirable species, occurs in much greater
numbers at Bartlett than on any of the other areas examined on the
Tvhite Mountain National Forest.

Analysis of Weeding

In 1932, 1933, and 1934, intensive plots wore established on cut-
over areas of the Bartlett Experimental Forest in order to determine
the practicability of weeding operations v/hich would increase the
proportion of desirable trees in the final crop. Tables II, III, IV,
and V combine the data obtained in two age groups; cut-over 4 to 8
years and cut-over 9 to 13 years previously. In each age group tvo
degrees of cutting were applied; a heavy weeding in which all trees
retarding the development of the crop trees were cut, and a light
cutting in v^hich only saplings ov0rtopp5nig the crop trees Yiere cut.

*

Van Nort, A. C. Reports on Initial Examinations of irhoelor Brook,
Batchelder Brook, Peaked Tiill, A. 9. Hall, and Peabody FuelY\rood
Cut-over Areas .

-3-

Tables II to V, in which crop trees are classified according to
D.B.H. and species, include only trees benefited by treatment. In
addition, the stands contain a considerable number of crop trees
which do not require releasing; approximately 15 percent on the
heavily cut areas and 20 percent on the light weeding plots. In-
cluded in the 15 or 20 percent are a considerable number of the
desirable species in the larger size classes. Other large trees of
the better species irmre not considered desirable for the final crop.

Approximately the same number of crop trees were benefited in
the several different types of weeding operations. The irregular
distribution of species and size classes indicated in a comparison
of the various tables is partially due to the small samples which
were the basis for Tables II, III, and IV. The average number of
weed trees cut and trainers reserved in the several zones within a
6* radius of the crop trees, as shoim in Tables II to V and Figure 2,
gives an indication of the treatment on the areas surrounding crop
trees, but slightly exaggerates the number of trees that would
necessarily be cut for each reserved tree as there was a certain
amount of duplicate tallying whore crop trees occurred less than
12* apart.

It is apparent that the average number of stems surrounding each
crop tree v/as about 25 percent higher on the more recently cut-over
areas; othen/viso the stands on the several series of sample plots
were very uniform. Approximately three times as many weed trees
were cut on a heavy as compared 7/ith a light weeding operation, and
in all cases proportionately more stems were cut close to the crop
trees (0 to 2* zone), as tlhe area of the 2’ to 4’ zone is three times
as groat and the 4’ to 6’ zone five times as groat as the 0 to 2’
zone .

On the intensive vj-eeding plots the areas cut-over 4 to 8 years
previously required an average of 4 and 5 man hours per acre res-
pectively on the light and heavy cuttings, while light and heavy
weedings required 3 and 4^ hours on the 9 to 13 year cut-over areas .
The time required for light cuttings was naturally lower than heavy
cuttings as fcv\rer stems wore cut. The heavy and light weedings re-
quired slightly less time in the older than the younger stands,
for altho the average size was larger, it v^as necessarjr to cut a
smaller number of stems. The time required on these plots is low
as the trees to be removed were marked prior to the v/eeding operation;
a desirable practice which would be impractical on extensive
operations, A moderately heavy cutting on a 110 acre stand sim-
ilar to the sample plots required an average of 9,5 man hours per
acre with C.C.C, labor, a figure more nearly what might be expected
on an extensive operation in similar stands. In comparing the
various methods of cutting which 7/ere tried on these plots, other
factors far outv/eighed the slight advantage in favor of high stumps
or partially severing the stems, as opposed to loiv stumps.

-4-

Organization of Crew

In organizing a crow to carry on a weeding operation, there
are several important considerations. Adequate instructions,
explanations, and examples of the proper procedure should precede
the actual cutting. A crow of 3 or 4 men under the close super-
vision of an experienced, technically trained man should become
thoroly familiar Y\iith the work, after viiich the crew may be
gradually built up to a maximum of 8 to 10 men, When the men
become thoroly familiar YJith this type of vrork, additional crews
may be built up from this nucleus. Some of the men trained will
be qualified to act as sub-foremen in charge of independent crews.

One technical foreman will be able to handle the supervision of
several small independent croiYS , each in charge of a sub-foreman,
and this Yrill prove more satisfactory than attempting to use a
single large crew. The cost of supervision will be relatively
high on a weeding operation, particularly while the work is being
organized. The vrceding costs per acre will be greatly reduced if
the croY/ members are carefully selected and the turnover is held
to the minimum.

The tendency to over-cut is a common fault of inexperienced
men on this type of work; this results in higher costs per acre and
usually injures rather than benefits the residual stand. Too much
emphasis cannot bo placed on the definition of weed trees which
consist only of trees that are retarding the development of the
crop trees ,

In a systematic Y/eeding operation the area can best be covered
by a crew working diagonally abreast. If this plan is followed,
the men working one of the end strips is responsible for the course,
the man working the adjoining parallel strip stays a short distance
behind, the third member of the crew lines in the same way on the
second, the fourth on the third, etc. Ordinarily each man should
be responsible for a strip about fifteen feet wide (the v/idth of
the strip depends on the type of growth) , and except in irregular
stands his v;ork will be confined to this strip. The foreman or sub-
foreman responsible for the job should work back and forth behind the
men inspecting the work as it progresses, at the same time instructing
and assisting members of the crew. As large, worthless trees which
should be girdled usually occur on cut-over areas, at least one member
of the weeding crew should carry an axe. In some cases the axeman
will necessarily spend all of his time girdling.

The method of cutting and selection of the proper tools are
important considerations in a weeding operation. The height of
the stumps has little or no effect on the number and vitality of
sprouts so the weed trees may be cut at any convenient height; about
15 inches if the stems are bent over when cut. Partial severing and
bending or breaking over the tops is as effective as cutting; the
resulting sprouts will probably be less vigorous than those growing
from clean cut stumps. Skilled axemen may prefer and do more work

-5-

ivith a li^ht axe or hatchet, but ordinarily a machete will prove the
most effective tool. The scissor typo prunor has advantages | skill
is not required for effective use, and the residual stand will not
be damaged in removing wood trees. Those pruners also have their
disadvantages as they are relatively expensive, occasionally get out
of adjustm.ent, arc somewhat heavy and not well adapted for cutting
large stems, and ordinarily prove less efficient than an axe or
machete properly h'andlod.

Conclusions

Yvoodings, particularly on the bettor sites and more accessible
areas, should bo given serious consideration in any intensive silvi-
cultural improvement program in northern hardv/oods . If suitable areas
are solcctod and the v/ork properly organized, the costs and benefits
of weeding will probably compare favorably 7/ith other types of cul-
tural work. On a considerable proportion of the recently cut-over
hardwood areas a wooding operation is the only moans of obtaining a
stand, any considerable proportion of which 770uld have a higher use
than fuelwood.

-6

TABLE I

Sapling Stand Per Acre on the Bartlett Experimental Forest,

C ut er ~.A7e as '

Stand

3-7 Years after

Cutting 'hi

* Total
Size ;

stand

Valuable

species

: Secondary
; spoci

Worthless

see lies — '

class : ho* of

: % size

Ko. of i 5'^ size

i i''] 0 . of? } 0

siz' ;

ho . of .

% size

: stems

; class

stems : class

: stems : class :

stniis ;

class

l'-5,9' H 6499

77.8

3209 37,8

4601

54.1

889

8.1

4'H-o5" D 1711

15.7

333 19.5

1044

61.0

• 334

19.5

0,6"-1.5" 578

5.3

55 9.5

467

80.8

56

9.7

l.S''-2,5" 76

0.7

34 44.7

42

55.3

0

0.0

2.6"-3.5" 53

0.5

25 47.2

28

52.8

0

0,0

Total 10917

100.0

3656 33.5

6182

56.6

1079

9.9

Stand

8-12 Years after

Cutting hJ

Size

class

Total

stand

Valuable g / ;

species :

Secondary- :

species :

Worthless g/

species

ho. of
stems

; /o. size
; class

ho. of:
stems :

';.o size :
class :

ho. of;
stems ;

% size ;
class :

ho. of :
stems :

% size
class

l’-3 9’ H

5838

53.6

2130

36.5

2926

50.1

782

13.4

4’B-.5‘’ D

3732

34.3

647

17.3

2635

72.0

400

10.7

o.e'* -loo”

827

7.6

138

16.7

637

77.0

52

6.3

1.6’' -2,0’’

308

2.8

113

36.7

174

56.5

21

6.8

2.6’’-3o5”

182

1.7

76

41.8

103

56.6

3

1.6

Total

10887

100.0

3104

28.5

6525

59.9

1258

11.6

jy" Based on 9 acre plots.

” ” 27 1/4 acre plots.

^ Includes red spruce, balsam fir, hemlock, yellow birch, sugar maple,
paper birch^ vfhite ashy black cherry,

^ Includes beech, rod maple, and aspen.

^ ” pin cherry, and striped maple.

I

4

1

5

i

TABLE II

For Acre* Sto-nd Tally of Crop Troos and Avo rage Number of Trainors
and Weed Trees on 4-8 Year Cut-ovor Areas, Bartlett, Now Hampshire

Light Weeding

Crop Troos

DBH
i nr; ho s

; White :

: ash ;

Sugar

maple

: Yellow
birch

paper

birch

: Red ; „ . ,

s spruoo s

Smaller

than BH

10

10

,2-. 5

5

35

45

30

115

.6-1.0

15

15

30

15

75

1.1-1. 3

15

5

5

5

30

Total

5

30

55

80

60

230

Trainors and Weed Troos

Distance from Crop Trees

0-2» i

2-

4» ;

4-6* : Total

i^.vjrago number trainors

per crop tree

3.6

11

.0

18.5 33.1

/iTorage number T.^oods

cut

per crop troo

1.1

1

.1

0.8 3.0

Total

4.7

12

.1

19.3 36.1

♦Based on two l/lO aero plots.

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TABLE III

Per Acre* Stand Tally of Crop Trees and Average Number of Trainers
and Y^ood Trees on 4-8 Year Cut-over Areas, Bartlett, New Hampshire

Heavy Weeding

Crop Trees

DBH ;

inches ;

Sugar

maple

! Yellow
: birch

: Paper :

; birch ;

Red :

spruce :

Total

Smaller
than BH

5

5

.2-. 5

25

15

15

20

75

.6-1,0

70

10

15

15

110

1.1-1. 4

10

5

15

Total

105

25

35

40

205

Trainers and ‘'.Yccd Trees

Distance from Crop Trees

0t2’ j

1 2-4«

j 4-6»

: Total

Average

number of

trainers

1 per crop

troo

2.1

8.7

15.1

25.9

Average

number of

woods

cut per

crop tree

3.1

3.4

2.5

9,0

Total

5.2

12ol

17.6

34.9

"^Basod on two l/lO acre plots.

TABLE IV

For Aero* Stand Tally of Crop Troos and Avorago Number of Trainors
anu W(;cd Troos on 9-15 Yoar Cut-ovor Areas, Bartlett^ Now Hampshiro

Light Wooding

Crop

Trees

DPH

s White

s Sugar :

YeiloYi;- j

1 Paper j

Total

inches

; ash

: maple ;

birch j

! birch J

.2-, 5

60

70

10

10

150

,6-1.0

50

30

80

Total

60

120

10

40

230

Trainers and Wood Trees

Distance from Crop Trees

0^2* :

2-4* ;

4-6*

: Total

Average number of
trainers per crop

tree

3.1

9.7

13.8

26.6

Avorago number of
cut per crop tree

weeds

0.8

1.7

1.8

4,3

Total

3.9

11.4

15.6

30.9

♦Based on one l/lO aero plot.

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TABLE V

For Aoro-H Stand Tally of Crop Troos and Avorago Ninnbor of Trainers
airl i/V.^od Troos on. 9-»15 Year Cut-ovor Areas, Bartlotb, Nov; Hampshiro

Hoavy Wooding

Crop Troos

DBH

inches

: Whito :

: ash :

Sugar

maplo

; Yellow ;

: birch :

Paper

birch

: Rod
: spruce

: Balsam
; fir

] Total

Smaller
than 3H

3

1

4

.2-. 5

25

11

3

5

5

1

50

.6-1.0

23

33

9

22

6

93

1.1-1. 5

4

10

8

18

5

1

46

1.6-1. 9

1

3

2

4

10

Total

53

57

22

49

19

3

203

Trainers and Wood Troos

Distance from Crop Troos

0'^2» j

2-4t

: 4-6* :

Total

/.verage numbor of trainors
per crop tree

2.0

6.8

12.0

20.8

ATorago numbor of woods cut
per crop troo

2.2

2.8

2.8

7.8

Total

4.2

9.6

14.8

28.6

♦Based on 13 plots; total area 1*9 acres.

AVERAGE STAND PER ACRE 3-7 YEARS AFTER CUTTING

THOUSANDS OF STEMS

FIGURE I- SAPLING STAND BY SIZE CLASSES ON THE BARTLETT EXPERIMENTAL FOREST.

4T0 8 YEARS AFTER CUTTING IN OVERSTORY

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