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United States Department of Agriculture
ALLE'GHEHY FOREST EXPERDiEHT STATIOIF-:--

Occasional Paper Uo. 1 Philadelphia, Pa.

Forest Se.rvice Hay 1, 1938.

RECOMJEIIDED TniBER STAUD IMPROFEiailT PRACTICES
( IN NORTIIERl'I BAPJ37roODS -HEMLOCK ON THE ALLEGHETIY PLATE AU

* by A. F. Hough, Assistant Silviculturist

The beech-birch-maple-henlock forest of the Allegheny Plateau differs
from the northern hardwood-conifer type as a whole chiefly in its high
proportion of blade cherry, and the absence of spruce and balsam. The
Allegheny Forest Experiment Station has since 1927 made this forest its
chief subject for study. However, it still regards as tentative any rec-
ommendations it makes of silvicultural measures to be here applied.

Objects of stand improvement

The purposes of timber stand improvement are as follows: (1) To
iraprove stand conditions within our forests for the growth of wood products,
(2) To benefit wildlife and recreation, and, (3) To protect watershed and
soil values.

Policy of ownership for public forests

Adiuini strati on of publicly ovmed forest land, such as State and
Federal Forests, involves the coordination of various uses of the forest
for the benefit of the public. Measures for tim.ber production must there-
fore take into account needs for wildlife, recreation, and watershed pro-
tection as well. The ultimate aim of timber management on public foi-ests
is to grow high quality long rotation crops of savfbimber and other products
on a sustained yield basis. An important part of this task is putting our
present day forest areas into shape by moans of stand improvement measures.

Present forest conditions creating need for stand improvement measures

Past cutting by commercial owners, often followed by fire, has
created large areas of culled old growth, and second or third-grovrbh for-
est on the northern Allegheny Plateau. (l) of "References Cited", p. 12.
Those may bo briefly described as follows:

(1) Culled old grovrbh mixed vj-ith second grov/th. Such stands
resulted, in the absence of fire, from, the logging of hem-
lock or Yirhite pine and leaving of a hardwood understory

•-!' In cooperation mth the University of Pennsylvania.

and scattered mature trees. Intolerant species seeded i

the openings made by logging and competed vdth advance '

seedlings of the understory to form now elements of the ‘
stand.

(2) Second growth of even ago which followed clear cutting of
virgin stands for logs and chemical vraod. In the absence

the usual stand is a mixed Iiardvrood forest with a
largo percentage of black cherry beneath which persist
sugar maple, beech, rod maple, yellow and black birch and
other species formerly present in the under story of advance
groTrth in the virgin forest at the time of logging.

(3) Third-gro-vvth stands which have resulted from the clear cut-
ting of immature second groivth for chemical wood. Because
there was little or no advance growth of tolerant species
beneath these young second-grovrth stands prior to logging,
much of the new stand is made up of stump sprouts, particu-
larly of black cherry and the maples, seedling pin (fire)
cherry and black cherry. Pin cherry and most stump sprouts
grow rapidly and may become formidable weed trees suppressing
slower grooving trees of better species and origin.

(4) Stands of aspen and pin (fire) cherry which have resulted
from repeated fires after logging. In such stands the stock-
ing of desirable species is very poor, the natural return

to better conditions is very slow and weedings are not
practical.

Common stand conditi ons

In general Yfithin these four classes of forest resulting from past
cutting or fire there are tvro common stand conditions affecting possible
timber production;

(1) A pronounced under stocl<ing of the entire stand, coupled with
a lack of desirable tree species, origins, or tree form,

(2) An ovor-crovrding of natural stands of second groivth and
presence of defective trees and y/oed species- y/hich reduce
both grovirth rate and quality.

Condition (l) is most frequently met vd.th as the result of fire fol-
low’ing heayy cutting or repeated clear cutting, while (2), over-croyyding
by both good and poor species, is usually found on the better sites in the
absence of destructive agencies.

Corrocti\re measures of general application

Fire protection is essential to prevent the addition of more
depleted forest land to the forester’s problem. Once a stand hs.s been

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V

depleted of good growing stock fire ptotociion and natural restocking may-
result in satisfactory conditions of regrovfbh but all too often this is
not true. Desirable future stands depend, not on fire protection alone,
but also on the application of silvicultural measures to care for the
developing new stand. Those stand improvement measures are, (l) -vrooding
in young grovfth, (2) thinning, liberation, improvement, sanitation and
salvage cuttings in second grovjth, (3) inprovomont, liberation and final
cuttings in old grovrth to insure adequate restocking of future stands.

Costs of stand improvement operations

Local data on the cost of various stand improvement treatments in
northern hardvrood stands are scanty and a-vailable figures vary Y;idely with
the kind of stand, intensity of treatment, skill of and -vwxges paid to
labor, supervision required and return from any marketable material cut.
Since mge scales vary, figures of man hours per acre are of greater value
in computing costs.

Weeding permanent sample plots on the Kane Experimental Forest in
13 to 18-year-old stands averaged 22 man hours per acre exclusive of the
detailed marking necessary for study purposes, (2) The work ivas done by
local experienced vroodsmen using the ax and pulTing all cut stems dovra.
close to the ground. No salable material resul’ted from this operation.

The same crew weeded 21,5 acres of 13-year-old v/ell-stocked sugar maple-
black cherry-pin cherry stands at the rate of 29 man-hours per acre, in- '
elusive of supervision by a foreman.

According to Cline (3) weeding of young nixed hardv/oods on the Harvard
Forest requires 8 or 10 man-hours per acre and best results are obtained
by an initial treatment 4-6 years after . logging follovred by one or even
two additional -vveedings three or four years ’apart. A stand developed to
the small pole stage by two early wee dings should be given an improvement
cutting at 17 years of age followed by a first thinning at 25 years, (4)

None of these early operations yield commercial products and labor v/iTl
amount to about 28 man-hours per acre in stands approaching a second thin-
ning, All subsequent thinnings should pay for themselves or shoYV a profit
through the sale of cordwood or small sawlog m.atcrial where markets are
available. The total direct outlay for early treatments Yvill thus amount
to about y20.00 per acre for labor and (iilO.OO per acre for supervision in
an intensively managed forest, (4)

In thinning unmerchantable stands girdling of all trees 5” d.b.h,
or over virill bo much cheaper and less damaging to the stand than cutting
down those trees, (5)

Benefits of stand improvement

The possible benefits of stand improvement cannot be given in dol-
lars and cents at the present time. Many are intangibles and may never
be fully evaluated. A complete scries of treatments applied to desirable
reproduction will ultimo-tely secure the follov/ing benefits:

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(1) Stands composed of tho raoro valua.blc spocics o.t time of maturity,

(2) More rapid grovrth iii volume of these crop trees,

(3) Crop trees of better form and quality vdiich mil bring a higher
price per thousand board feet,

(4) Loss natural mortality and loss of volume due to disease and
insect attack because of grov/ing conditions favoring good vigor
of crop trees.

(5) Maintenance of soil or site quality, and ivatorshed protection
values .

(6) Increasing food available to Tfildlifo as a result of cuttings.

(7) Improved aesthetic and recreational values.

(8) Social benefits from continued production of forest crops,
profitable employment, and stabilization of local communities
dependent on tho forest.

Kind of stand effectively treated and agency to do tho v/ork

In general all stand improvom.ent operations will prove to be most
effective when confined to the better stands and the bettor sites, Tho
agency best fitted to do this YiTork should bo carefully considered for
each stand or compaid:mcnt treated, l^ncrc a coimnorcial cut is obtainable,
and can bo readily marketed, contract sales of marked trees should be made.
In other areas, local or CCC labor may bo employed in stands too j^'oung to
produce merchantable products, or too far from existing or possible future
markets to bo attractive to forest industries.

Priorities of CCC stand improvement v/ork

First priority in CCC timber stand improvement work should bo given
the wooding of young groivth stands boti'TOon 5 and 15 years of ago. Possi-
bilities for betterment of stand conditions arc greatest in such young
well-stocked stands, and the' danger of creating^ disease hazards is loss
than in older stands. Thinning of second grovrth is next in importo.nco
from the standpoint of benefit to the stand and much larger areas are avail-
able for this treatment than for any other. Liberation cuttings, especially
those designed to release conifers beneath an inferior hardwood ovorstory,
should bo made in both sccond-grovrth and old-grovrth stands.

As a result of the glaze storm of March, 1936, covering 6,000,000
acres in Pennsylvania and Ko^v York, it vrtll be necessary to make sanita-
tion and salvage cuttings using CCC labor on unmarketable stands.

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stand improvoncnt in young g'rovxbh

Methods of wooding

Since it is impractical to treat all trees, or even all potential
crop trees, on a given vfoll-stockod area the accepted method of wooding
is to select a certain number of crop trees and to rom.ovo only the trees
Y/hich interfcK3 Y/ith them. Choice of crop trees is usually considered
necessary during the process of Yveeding. The o.ttachod list, (Appendix
P. 1), classes all common tree species as (l) desirable, (2) loss desir-
able and (3) least desirable. Choice of individual specimens depends on:
tree species and origin, bole and crovm form, defects, size, rate of
groYYbh, and spacing, (6), (7)

Treatment consists of rcm.oving only those trees overtopping the
selected crop trees. Largo sprouts bot^Ycon crop trees whicH 'threaten
their future grovYth, though not at present overtopping, and badly-diseased
or insect infested trees, should also be cut. Trees of crop tree quality
betYYcen those selected at the regular spacing Ydll be disregarded and no
treatment for their benefit Ydll be given, (6), (.7)

The degree of release to be given should be based on the ImoYm
habits of groidh shoYm by seedlings and sprouts of various species. In
general the tolerant sugar maple, hom.locl: and beech vd-ll require a greater
araount of release (especially if previously subdominant duo to competition)
than YTill the already dominant o.nd rapid groYYing intolerant s such as black
cherry, yolloYY poplar, cucumber magnolia and vYhite ash, (6)

The most effective tool for use in very young. (5-yoar-old) stonids
is the machete. (3) Vflion the stems to bo cut arc larger than 2" a light
ax is the best tool. Other tools YYhich have been used are brush hooks,
pruning shears, meat cleavers and heavy ]aiives,(8), (9)

The nujnbcr of crop trees selected per acre should alv/ays be greater
than the number desired at stand maturity in order to insure against nat-
ural mortality and the failure of treatment in bringing all individuals
through early competition. Figures obtained by the Station (6) indicate
that in virgin hardvYood stands 200 square feet is about the maximum basal
area obta.inod. This v/ould permit a stand of 143 trees of 16” d.b.h., 113
trees 18” d,b*h, , or 92 trees of 20” d.b.h, per acre. At least double
these figures should be used or 184 to 286 trees per acre in 10-15-ycar-
old stands to alloYT for mortality and thinnings in subsequent years. A
square spacing of 12-1/2 feet VYOuld give 279 trees per acre, a.nd 15 feet
about 200. TJniforra spacing should bo the ideal aimed at but must bo sacri-
ficed in order to select the trees best fitted to form the final crop. In
selecting crop trees judgment as to the rcla.tivc desirability of various
trees on or near the properly spaced points must be exercised by each creYY
member. Deviation from proper spacing should be permitted but crop trees
should not be spaced closer than 10 feet from an adjoxent crop tree in 10-
15-year-old sto.nds.

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Ilethods of removing weed trees will ordinarily be complete sever-
ance at any convenient stump lieigTit, crop trees are small and there

is danger of vigorous resprouting from adjacent large stump sprout clumps
it Ydll be advisable to make a pc.rtial severoLnce of such weeds and bend
down their orovnis to discourage the fomoution of nevf sprouts. From the
sto.ndpoint of deco.y hazard to crop trees it is very important to leave
only 0. single stem (the crop tree) by basal severance of all other com-
panion sprouts o-ttached to the sv.r.ie root system. Even though certain
valuable trainers are so sacrificed the danger of. decay from future high
unions, dead stubs, or future severances in thinning when the stems are
lo^rgcr and closer together vj-ill be avoided. Bending companion sprouts
dovra and cutting with an ax is sat is fact om>'', and, if the sprouts are under
1" or even 2" in diameter at the base there is little danger of decay.

Avoid high stubs wlien subsequent gror/th vfill result in rubbing and injuring

the bark of the favored sprout, and prevent dama.go to the crop tree stem..!/

i7

An efficient crew organization for the conduct of vreeding vrork is
made up of 4 to 8 axmon and o.n cxperionccd foreman. Adequate instruction,
examples of proper procedure and close initial supervision vd.ll be neces-
sary until the men become thoroughly familiar with the vfork. This train-
ing should bo given by a technically trained forester. Additional crev/s
can be built up from this nucleus. Careful selection of crew members and
a low rate of turnover vdll greatly reduce the wooding costs per acre. (8)

The area to be weeded can best bo covered by the crow vforking
abreast at stated intervals. Each m.an covers a strip 12 to 15 feet wide.
The foreman should vrork back o.nd forth behind the men inspecting the v/ork
and instructing and assisting members of the crcviT.

Foremen and subforemen vdll be in, direct charge of the crev/, eaid
vdll be responsible for the Idnd of treatment given and the area covered.
The technical forester or foremo.n should inspect the work frequently,
check reports o.nd maps, plan the areas and classes of treatment for all
crews and make check tallies of sample plots vdth each forena.n to deter-
mine the degree of compliance vdth instructions.

Pruning

In well-stocked stands of natural reproduction the artificial prun-
ing of selected crop trees vdll seldom. be necessary. Pruning of plantations
made up of such conifers as white arid red pine will, however, be justified
in increasing the quality of the product. There is little known a.s to the
cost, methods, or effects of pruning our native hardwood species.

Decay frequently enters the hardwoods through dead branch stubs,
particularly when of largo size. Since vj-ounds created by pruning large
livo branches arc also serious decay hazards it is necessary to confine

sucli opcro.tions to the small branches of young crop trees. It is gcncr-

l/ From memoranda in files and note in Forest Pcscarch Ilonthly Report,

U. S. Forest Service, of December 1937, p. 26, by Dr. W. A. Campbell,

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o.lly aglTGod that branches larger than 1 inch oi* at raost I-I/2 inches in
dianetei* should not bo pruned, (10) Pruning my also check the groi/^th of
a tree ■when too drastic a reducTTon of the length of , live _ crovm is' nade.(ll)

In understocked, linby, hardwood young grovvth, v/ooding in the sense
of releo.sing crop trees may not be required, but removal of companion
sprouts at the base of all prospective crop trees and pruning to keep dovm
limb size are both measures which avill reduce future decay and should
markedly increase the chances of producing material of greater ■value than
fuelvrood.

Mowing advance grov/th

It has been comi'aonly observed that sapling and smaller Q.d-va^nce under-
story sugar maples are frequently of poor fomi. and are damaged by hoctria
co.nkors. It is loiovm also that ■the seedling-sprouts resulting from cutting
back such advance grovrth are superior in fori'a, health and grovrth rate to
the original seedlings, (12 ) YiTeak sprouting species such as beech and the
birches v/ill of course be discouraged. This operation had best be done
during the late vdnter or early spring before rapid gi-ovvrfch begins and not
during the height of the growing season. If done o.s a separate CCC opera-
tion it should ordinarily follow imi'.ied lately after a v/inter logging job
is completed. A brush scythe or brush hook will prove -bo be the best tools
to use in this work. All conifers should be preserved from movdng o.nd this
work had best be confined to areas supporting a dense understory of saplings
or small •'.vhips made up chiefly of suppressed sugo.r maple. Ylien the bulk
of the understory stand is made up of the v/eakly sprouting species, such
as beech and the birches, mowing should not be done.

Treatment of stmaps to eliminate or reduce sprouting

One of the chief reasons for weeding young gro^-vbh stands is to remove
aggressive weed-tree elements vdiich have domins.ted desirable crop trees.

These weed trees are frequently the vigorous wide-spreading stump sprouts
of such specias as red maple and black cherry as v/ell as trees of the least
desirable species. It is possible as an aid in subsequent vreeding to pre-
vent the sprouting of stumps or at least reduce the vigor of such sprouts.

This form of stand improvement is applicable to areas from, vrhich in'umturo
second growth has been clear cut and mo-y be used where the land is more
vo.luable for future saTjtimbcr production than for cordv/ood.

Methods being tested by the Sta.tion following a glaze sanitation
and salvage cutting in 40-ycar-old second grovh:h include girdling of stui^.ips,
peeling bark to ground line and lniocld.ng off the sprouts during mid- summer. (13
Other possible methods include the o^pplicatiori of Diesel oil or sodiuin
arsonitc. Evddence a't hand indico.tes that cutting or breaking off the first
or second seasons’ sprouts in mid-sumD^ior \/ill prevent resprouting in about
SO percent of all black cherry stuiaps treated, (13) Since black cherry
stur.ip sprouts are ■bhc worst weed-tree offenders and the rot hazard is high
in sprouts of this species their early climina.tion is recommended in stands
dedicated to savirtimbor production.

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Inter- o.nd undorplc-ntinr;

In nany .eases tho.:only possible ncans of inproving the stocking
.and species conposition of open-grow stands would seen to be through the
intcrplanting 'of conifers. Red pine is known to be the nost successful
species to use on the vrcll-di-'ainod sites when stand density of native
hardvroods is not too great, Irrcgulo.r sx^acing to avoid clunps or dense
patches of established grovrbh nay be used.

Undorxolanting of the bettor stands of the booch-birch-naplc-hcnlock
forest region is not a practical nethod of inproving the young gro'wth due
to high initial cost of cstablishr.icnt, slow' growth of the understory and
difficulty of bringing it through the severe conpetition offered by native
hardwood roprodiiction after the release cutting is no.dc. In fire-degener-
ated sto.nds of aspen-pin cherry, underplanting v/ith spruce offers a neans
of inproving the conposition. (14) Since conpetition by the better hard-
vrood species is not serious there is a good chance of the spruce coning
through successfully after the aspen and pin cherry aro cut.

Stand improvenent ncasures in second grov/th

Thinnings and inprovonent cutting s

ITncn an initial inprovonent cutting has been delayed until the
stand has reached an ago of 40 or more years it is usually inpossible
greatly to change the species conposition or the fom, health, spacing,
and quality of the doninant stand. It is evident that inprovonent cut-
tings or thinnings should be preceded by Virocdings and cannot alone produce
0. high quality stand, llhcro narkots for cordwood .exist it will be best to
thin as soon as sufficient natcrial to' pay.,for. the operation is available,
or about 25 to 30 years of ago, and continue to nakc light thinnings at
about 10 year intervals until the tine of final cutting.

Second -groTvth stands in northwestern Pennsylvania, of sufficient
ago to bo profitably thinned, arc frequently donino.tcd bjr black cherry or
holdover beech of cordwood fom. The ini^rovcnent cutting practice rccon-
nendod in such eases depends largely on the availability of desirable
species of potential crox)-trcc calibre associated vd.th these cordvrood
cloncnts. Plot studios by the Allegheny Station indicate that cutting of
the nost defective trees in 40-year-old stsjids (or about 10 cords per
acre) seriously breaks the crov/n canopy and thus increases the hazards of
sun scald, v/indthro¥/ and windbreakage, and glaze danage to the reserved
trees. The birches and to n lesser extent beech, Tfill not survive a heavy
opening of the stand and cannot be depended on to forri a reserve growing
stock. Sajpling and snail pole-sized sugar naple of single stenmed clear-
boled character fom. the ideo.l croj' ti-ees and respond vrell to a release
cutting fron above, Sto.nds nade up chiefly of blOvCk cherry and sugar naple
nay thus be given the necessary thinning fron above, to renovo doninants
of cordwood forn wdth o. reasonable hope of leaving a successful reserve
sto.nd of desirable sjpecies, good fom^ and origin, proper spacing and lovf
nortality, (15) On the other hand stends in viiich yellow and black birch

ar‘e doninantj or form the chief undef^tol:*y; are practically inpossihle to
inprove by cuttings nadc in older stands of* second grovjth. Hindsight
indicates that early v/eedings or even some change in the cutting nethod
used on the origirjal stand would ho.vb bettered the conposition of such
stands. The practical ansT/Tcr to the question of what nay bo done at the
present tine in such stands is not known. Until , studios give .this infor-
nation it is reconnonded, (l) that stand inprovenont cuttings or thinnings
in stands vrith high percentages of the birches be given a low priority un-
less glaze dana.gc or dying of birch is serious, and (2) that any cutting
bo nado as light as possible and as frequently as possible with the idea
of gradually replacing the undesirable olonents without excessive exposure
of the site as contrasted Virith heavy infrequent cuttings.

Studies by the Bureau of Plant Industry indicate that severance of
conpanion sprouts in stands over 20 years of age is dangerous from, a decay
hazard standpoint. In stands which vrcro not v/oeded when young it is best
to cither cut all nenbers of a sprout clump or leave then entire to lesson
decay entrance from cut stubs, (16)

Sanitation and salvage cuttings

hhere existing road systems and markets perrait, coimacrcial sales of
severely damaged stands should be nado in glaze susceptible areas. The
treatment to bo given each stand vm.ll vary with the degree of glaze injury
sustained and the character of the original sto.nd. In lightly daraagod
stands of desirable second grov.rth, po.rtial cutting to remove only severely
damaged trees should be used. Clear cutting nay be the only solution in
badly damaged stands. In cither case the effort should be made to preserve
a,ny undamaged pole sized understorv’- of desirable species such as sugar maple,
hemlock, etc., as the nucleus of the future stand and to folloav out the
technique rocomi.icndcd for stand improvement cuttings wherever possible.

Definite pls,ns for early stump treatment, mowing and weeding of this
third grovrth should be nado, especially in the case of arco.s from v/hich
immature stands of second grovfth have been clear cut. The policy should
be to cncouro.gc the grovrth of o,ny rn-tivc conifers on the exposed ridges or
north slopes likely to be glc.zc dana.gcd in the future, since it has been
found they resist this form of injury much better than any of the hard-
woods, (17)

Sanitation cuttings for the reduction of Hoctria cankered or other
diseased trees should bo based on principles outlined for glaze damaged
stands. Grant (18) sug^..csts the possibility of converting severely cankered
hardwood stands, vrhich are potentially valuable for softvrood so.vrtim-bor pro-
duction, by the spot planting of conifers (spruce, fir, and pine), together
vdth release of any natural softwood reproduction, as a slow but rather
inexpensive ivay of getting such marginal stands into permanent production
of vo.luable disease free species.

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Liberation cuttings

A fairly coniiion stand condition noted in the beech-birch-naple-
henloclc forest region is the suppression of an under stor^' of henlock by
an inferior overstory of hardwoed such as decc.dent beech, less desirable
red na'ple, or birches subject to the bronze birch borer. Such stands vd.ll
be improved by a liberation cutting to release the lienlock. Examples of
very rapid grovrth of henlock after full rcleo.se by past cuttings, or after
vdndthrov; of the ovenvood in virgin stands, give assurance of the o.bility
of suppressed trees to respond. Either girdling or cutting dcam the hard-
vrood overstorjr no.y be used. Girdling vdll prove clieo.pest in labor used,
v\dll probably dcaaage the henlock less and is justified vdiere there is no
market for the hardvrood to bo removed. A complete treatment removing all
the overstory at one tine is the practical method to employ and should
result in little damage to the undcrajeory honlock because of exposure.

If the understory hemlock is also suffering severe competition vdth hard-
vfood reproduction the treatment should also include a vj-oeding to remove
stems of the hardwood species either by complete or partial severance or
by girdling larger individuals.

Similar liberation and vreoding troc’.tncnts could be used in the co.se
of vdiite pine reproduction found bones. th poor quality second or third
growth hardvTOod stands, providing v/oc\oil and vdiite pine blister rust control
funds aro available. Except for the rcmovvil of occasional vrolf trees
hampering reproduction on clear cut areas, it vdll usually be unnccGsso.ry
to make special efforts to release hardvrood o.dvc'.ncc growth of tho desiro.blo
tolerant species prior to final cuttings. This is particularly truo of
fully stocked socond-grovdh stands' beneath which desirable tolerant o.dvancc
groivth seedlings arc usually small, and not to bo depended on to dominate
the new stand in competition ivith the intolerant v/ced olomcnts.

Stand improvement measures in old grov.’th

The final harvesting of old grovdh or mature sccond-grovdh stands
and their replacement by dosirable young grovdli is not usually thought of
as a stand improvement operation. Actually the method of final cutting
used is one of the most importo.nt factors in cither building up or in
deteriorating the forest grovdng stock.

It is gcnero-lly accepted that ccrto.in partia.l cutting systems of
harvesting mature tirber arc to bo preferred to clear cutting in the beoch-
birch-maplc-hcmlock forest region particularly v;hcrc a well formed under-
story is lacking. This is based on the fact that partio,! cutting by cither
a tree scloction or sholtcrwood system, using a sawfcinber rotation, maintains
stand conditions favoring the bulk of the desirable' species, viiilG clear
cutting, especially on a short rotation, fo-vors the intolerant vrcod species
and trees of sprout origin, (19) The selection system should bo used where
stands arc ' acccssiblo and a continuous ^roarly suppler of quality products
is desired, providing the given stand has a structure, i.o, roprosontatives
in all diameter classes, adapto.blc to this method, Ylhorc such conditions do
not exist, a shclterwood method of cutting should be applied, while in very

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dcfoctivc old grovrbh vdth o.xi abUndo^nt; Understory of desirable species
clear cutting my be the .only solution-? possible.

Stands of virgin timber in public omiers’iip, ^diich are being held
for timber mnagenent purposes, are rare but there are many areas of culled
old grovdli nixed vdth second grovfbh which are now uerChanic'.ble. _ Treatments
designed to improve these latter sto.nds should be/coilfined to those in
which the overstory is verj'' defective and v'diere oai understory of reproduc-
tion of desirable species is very sparse. In order tq encourage the develop-
nent of the necessai-y advance growth to fon.i the basis of a new stand it
mil be necessanj/- to girdle or cut some of the doninant trees to nahc open-
ings in the canopy. The trees selected for ronoval should be mdcspreading
individucLls of defective bole forT.i or heowlth and of least corxiercial value
especially if girdling is the method used. In both the selection onid
shclterwood system it is advisable not to leo.vo beech and the birches in
an exposed position because of the danger of mortality. Following the
establishment of this understory, fino.l cutting may, if necessary be delayed
for a nuiaber of years mthout killing out the very tolerant seedlings of
sugar maple, beech and hemlock. Such a method of stand improvement is in
effect a shelterwood cutting and the final cutting should completely remove
the overvfood,

Follc./ing a final cutting by the shelterwood, or the clear cutting
system, it is essential to provide for v;eedinrs of the new grorrth as previ-
ously outlined, in order to discourage v/eed tree dominance of the o.dmnce
grovrth. Less of this kind of work vail be required in sto.nds handled on a
tree selection basis because the v/eed species are usuodly intolerants.

Use of cor.miercio.l timber sales should be made, wherever possible as
a tool in stand improvement. In all fina.l cuttings ca,reful consideration
of the silvicultural system to be used and narking of the. inplividuo.l trees
on the ground is essential. Since cutting on. a short rotation will not
yield high quality products and v.dll result in' deteri.oro.tion of the new
stand, fino.l cuttings should be mo.de only in old growth or nature (80-120-
year-old) second growth.

-11~

References CltCd

■ MW... - ■

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

HougIi, a. F. 1937

Silvicultural problems of the beech-birch-naple-henloclc
forest region in northv/e stern Pennsyl-vo.nia.

Mss, in files Allerheny Forest Experiraent Station.

Ostrora, C. E. 1937

Establishment report for Kane Experinento.! Forest weeding
plots.

Mss, in files Allegheny Forest Experinent Station.

Cline, A. C, 1929

Forest v/eeding with special reference to young nci.tural
stands in central Hew England,

Bull, of Mass. For. Assoc. Frepon-ed at Harvard Forest 1929

Cline, A. C. 1935

Inprovenent cutting and thinning as s.pplied to central Hov;
England hardwoods.

Mass, Forest and Pa.rk Assoc, Bull, Ho. 155. Prepared o.t
Harvard Forest 1935,

Sto.ff of Appalo-chian Forest Experiiaont Staation 1935

Forest inprovenent measures for the Southern Appalachians.
U. S. Dept, of Agric, Tech, Bull, Ho, 476.

Hough, A, F, 1936 • ; ,

Plan for Yreeding study - Ka.ne Experinento.l Forest.

Mss, in files Allegheny Forest Exporinont Station,

Anonymous 1935

Timber stand improvement treatment - Allegheny Hational
Forest ,

Mineo. Allegheny Hational Forest Form v'lSl, 7/l0/35
Jenson, Y. S« 1935

Suggestions for vreeding in northern hardaroods.

Occasional Paper No. 3 Northeastern Forest Experiment
Sta.tion, Mineo.

Yfestveld, M, 1935

iHeeding as a stand improvement measure on cut-over spruce
lands. Occasional Paper 7g5, Northeastern Forest Experiment
S tat ion. Mine o .

Lorenz, R, D, and C. M, Christensen 1937

A survey of forest tree diseases and their relation to
stand inprovenent in the Lake o.nd Central States,

U.S.D.A. Bur. Plant Industry. Mineo. 52p. Ulus, v-rith
11 plates.

-12-

(11) Mayer-Wegelin, Plans 1936

Fruninc. Trans. ^264 U.S.F.S. (Rib. in Hanover, GemOony
1936)

(12) Hough, A. F. 1937

A study pf natural reproduction in the heech-birch-naplo-
henloch type.

Jour. For, Vol. 35: 376-378

(13) Ostron, C. E. 1937

EstablislTnent report - blacl: cherry stunp treatnent.

Mss, in files Allegheny Poorest Expcrinent Station.

(14) Hetzel, J. E, 1937

Report on the cooperative survey of plantations of Alle-
gheny Plational Forest ojid the Arnstrong Forest Conpan^^,
Mss. in files ef Allegheny Forest Experinent StOttion.

(15) Ehrhart, E. 0. 1937

Vierfs of a private forester
Jour. For, Vol, 35: 571-573

(16) Campbell, YiT. A. 1937

Sprout clunp reduction and the decay hazard shovm. bj;-
thinning operations on the Sllithorp fam near Ko.ne, Po.,
Mss. in files Allegheny Forest ExperijAent Station by
Dr. 17. A. Co.npbell of Bureau of Plant Industry.

(17) Dov/ns, A. A. 1938

Glaze damage in the birch-beech-maple-henlocle type of
Pennsylvo.nia and ilev/ York.

Jour, For. Vol. 36; 63-70

(18) Grant, T. S. 1937

Reduction of Hectria canker in hardvrood forests of the
Northeast.

Occasional Paper p-6, Northeo.stern Forest Experiment
Station, Mimeo.

(19) Ostrom, C. E. 1938

Clear cutting of young northern hardwood.

Jour, For. Vol, 36: 44-49.

-13-

Appendix

FACTORS TO BF CONS IDFRFD IN TUN CHOICA OF INDIVIDUAL
CROP TELLS IN TSLDIIIG, THINNING, AlTD STAND II IPROVLILHIT
PILiCTICLS IN THE BLECH-BIRCH-t.IAPLL-IILlHOCi: FOREST REGION

I Species:

Relative desirability
DesirSible

Sugar r.iaple
Rfhite ash
Black cherry
Eastern henlock
Yellow poplar
Cucunber nagnolia
Beech
Red oalc

of coi'.rr^on species for
Less desiro.ble

Yellovif birch
Sweet birch
Basswood
Red naple
Eln

Paper birch
Gray birch
Y'Jliite pine

savjt Iv.ber pr oducti on. *
Lec.st desiro.ble

Pin cheri'y
Aspen

Striped naple
I.iounto.in naple
Serviceberry
Blue beech
Hop-hornbeau
Hawthorn
Nountain ash
Boxelder

II Origin

Well developed seedlings, or sprouts arising fron sno.!! stunps 2
inches or less in dianeter (coruaonly called seedling sprouts) are to be
preferred as crop trees. P.Tien trees of such origin are not available
sprouts of sugar naple fron stuiaps 3-10 inches in dianeter nay be treo.ted
to produce a single crop tree sten by severance of all companion sprouts
on the sarae stool. Decay hazard is light provided this w'ork is done in
stands 5-15 years of age. Sprouts originating at 2 inches above ground
or less and fron snail stuiaps (3-6 inches in diovieter) are to be preferred
Sprouts of blo-ck cherry and red naple fron stunps 3-10 inches in dianeter
are very aggressive o^nd are less desirable as crop trees even vrlien of root
collar ori{:in.

Root suckers of beech and sugar naple nay be used as crop trees
providing they ncet other requirenents.

Sprouts fron the sides or top of largo stunps are undesirable in
the case of all species and decay hazards are high, especially when they

Bo.sed on the tcchnico.1 properties of the wood, o.nd such factors as vigor
and grorrfch rate, ability to endure conpetition, nr.ture size, forn, repro
ductive ability, and freedon fron disease, insect and aninnl danage.
Present narket value and vo.lue for wildlife food, or erosion control,
considered as secondG.ry factors.

oririno.te o.t points above tho root, collar.

Ill Bole o.nd crovTL fom

Crop trees should bo the straiphtost individuals possible to select
T;ith tho nain sten continuing up through the crovm. Crooked or forked
trees ■'-d.ll be discrinimt.-.d o.painst ospocio.lly if the fork is o.t o. point
bolov7 16 feet or one log length, Linby vn dosnreo.ding trees should ordi-- ■
nc.rily not be selected because of the lovr gro-do of Ivniber prodvTced and
their tendency to "v;olf’' proving spc^co. Trainers to discourage tho forma-
tion of persistent lov side branches should be loft, particularly around
rapid proving intolerants such as black cherry, vhito ash, bassvrood onid
yollov poplar. Trees vhich hc.vo had thoir crovns badly da;aagcd by glo.zo
should bo discrii’.inatod agomnst in stand inprovenont operations.

IV Defects

Iniuries due to disease, mechanical vroundinr:, rodent damar’c, insects,

O 7 O J O 3 3

climatic injuries and other causes influence tho health of trees. In
picking crop trees a careful exonination and cvaluo.tion of the seriousness
of any visible defects must be made,

A common disease in northern hardvraod species is co-nkoring caused
by hectria sp. Rod mple is most susceptible to this disease and cankered
stems should not be chosen o.s crop trees, Sugo.r maple is o.lso subject to
this disease but vigorous young crop trees vdll probo.bly outgrov sno.ll
cankers if released by veeding. Open vounds caused by- fire , logging, vind
or glaze brealcc.ge, porcupine gnaving, drought or sunsco.ld, are serious
defects in any tree considered as a crop -tree specimen and become entrance
points for fungi- and insects. In general the lo.rger the size or greo.ter
the number of such vounds the less the value of the tree. Yfounds vith
fungus fruiting bodies shov definitely that the tree should not be favored.
Poor risk trees expected to die before the next cutting oporo.tion should
be salvo-god in o.ny stoaid ir.provenent opero-tion.

Of common insect enemies the bronze birch borer, Agrilus arxius Gory,
cc.uses serious losses in yellov and black birch. Because of this the
birches- should never be exposed by heavy cutting or on a south-fo.cing for-
est edge and should be favored as crop trees only on north-facing slopes
and streo-m bottom sites, Tho sugar maple borer is also a serious post
as are tho living beech and the hemlock borers.

V Size and rate of grbivth

The mature size of all tho dosii’ablo and most of the loss desirable
species listed is satisfactory for sa-vtimbor production. The most rapid
groving dosirablo species are blo.ck cherry, yollovf poplar, cucumber magnolia
caid vhito ash vhen 'represented by dominant trees on good sites, Tho other
desirable species are tolerant and capable of very slovr grov/th vhen sup-
pressed, but respond to release and make very satisfactory grovfth vhen

-•2-

uncrowdcd. In rrccdinr practice it is a general rule to select crop trees
of avera.ge or slightly above average lieight. Trees too far abox^e the
average tend to develop into Y^rolf trees v/hile those beneo.th the general
croivn. canopy have under-developed roots onid crovais and my not respond
satisfactorily to treatnent. The extrenely rapid initio.l grovfbh rate of
black cherry sprouts and their tendency to spread o.nd fork is another
factor naking them undesirable as crop trees in stands to be managed for
sairTtimber of high quality. In thinnings or improvement cuttings careful
judgment is necessary in order to select trees vhich vrill respond to treat-
ment by increasing their grovh:h rate and to concentrate this gro\-rth on
high quality trees. The use of an increment borer in determining the past
rate of gronrth in trees of various species cuid crovm classes is recommended
as a check on genero.l observation.

VI Crop tree spacing, either in the initial weeding of a stand contain-
ing 2000 to 5000 or more trees per o.cre, or in the thinning of an older
stand, cannot be made mechanically perfect. Lack of exact uniforr.iity in
spacing of crop trees is less of a fault than failure to select the best
individual trees occupying the given area. Approximately 280-300 crop
trees per acre should be selected in stands 10-15 yec.rs of age ojid a square
spacing of 12-1/2 feet should be used as a guide. In crew work each nan
must judge the relative desirability of vr.rious trees on or near the properly
spaced points and if none are suitable must proceed along this line noting
all trees on either side to o. distance of about 6 feet until a desirable
tree is found, ilo crop tree should be closer than 8-10 feet from an adjo.cont
crop tree in lO-ld-ycar-old stands.

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