A Management Guide
in N e w England
/
Adrian M. Gi1bc.t and Viaor S. Jensen
- -
STATION PAPER NO. 112
FOREST SERVICE
NORTHEASTERN FOREST EXPERIMENT STATION
U.S. DEPARTMENT OF AGRICULTURE
RALPH W. MARQUIS, DIRECTOR
1958
UPPER DARBY, PA.
The Authors
ADRIAN M. GILBERT had his professional training at the University of Michigan and the Swiss Federal Institute of Technology, Zurich, Switzerland.
He joined the U. S. Forest
Service in 1946 and served for a while in the Forest Survey
of the Northeast.
Since 1952 he has been engaged in research in the silviculture and management of northern hardwood forests, and is leader of the northern hardwoods project at the Northeastern Forest Experiment Stat ion's research
center at Laconia, New Hampshire.
VICTOR S . JENSEN had his professfonal training at the University of Minnesota and the Yale Forestry School, and spent
several years in ad~ninistrativework with the U. S. Indian
Service and the U. S. Forest Service in Oregon, Washington,
Idaho, and Utah. Except for 2 years as War Production Board
lumber advisor for New Hampshire during World War 11, he has
served with the Northeastern Forest Experiment Station continuously since 1929, mainly in research in management of
northern hardwoods. He is in charge of the Experiment Station's research center at Laconia, New Hampshire.
~HRU
yemenr
wide
for
Adrian
ert and Victor S. Jensen
Northeczstern For
Forest Service,
intent S t a t ion
. ARriculture
Contents
1 rn The northern hardwoods i n New England
3
Scme c h a r a c t e r i s t i c s o f t h e northern hardwoods
Species
Sites
Old growth
Second growth
4 rn Old-growth f o r e s t
Silvicultural system
S e l e c t i o n system c u t t i n g
Patch c u t t i n g
Clear c u t t i n g
S t o c k i n g , s t r u c t u r e , and growth
High-value products
Bulk products
14
20
21
Second-growth f o r e s t
Silvicultural system
Clear c u t t i n g
S e l e c t i o n system c u t t i n g
Tending the stands
Cleanings
Thinnings
R o t a t i o n and stocking
High-va lue products
Bulk products
rn General remarks
rn L i t e r a t u r e c i t e d
I
The N o r ~ h e r nHardwoods
in N e w England
ORTHERN HARDWOOD f o r e s t s occupy about 9 m i l l i o n
a c r e s of land i n New England. In recent years, these
hardwood f o r e s t s have made i n c r e a s i n g c o n t r i b u t i o n s
t o t h e economy of t h i s r e g i o n . T h e i r f u t u r e management
should be even more rewarding.
This guide has been prepared f o r use i n managing the
old-growth and second-growth n o r t h e r n hardwoods of New
England. It is intended t o h e l p c h a r t the course of management f o r the i n i t i a l c u t t i n g c y c l e s on previously unmanaged
f o r e s t s . The suggestions presented sumnarize the r e s u l t s of
25 y e a r s of r e s e a r c h on t h e B a r t l e t t Experimental F o r e s t ,
J h r t l e t t , New Hampshire, and elsewhere i n the region.
Table 1.--Some
Species
Tolerance
characteristics of northern hardwood species in New ~ n ~ l a n d '
Response
Growth
rate
Management
objective
Risk
Reproduction
Sugar
maple
Very
tolerant
Responds well to
thinning or release.
Moderate
to fast
18-24"
d.b.h.
Healthy tree. May be deformed
by maple borer.
American
beech
Very
tolerant
Responds well to
thinning or release.
Moderate
14-20"
d.b.h.
Poor risk because of Nectria.
Subject to frost and sunscald
damage.
Abundant root suckering.
Seeds every 2-3 years.
Yellow
birch
Intermediate
Fair response to
early tbinnings.
Slow
18-24"
d.b.h.
Sensitive to high soil temperature and sudden exposure.
Dieback and post-logging
decadence.
Poles sprout.
1-2 years.
Paper
birch
Intolerant
Responds to early
thinning.
Fast
60-70
years
Sensitive to sudden opening
and high soil temperature.
Dieback and post-logging
decadence.
Seeds most years. Moderate
stump sprouting.
mite
ash
Intolerant
Responds to early
thinning.
Moderate
to fast
14-18" d.b.h.
70-80 years
Healthy tree.
Seeds every 3-5 years.
Red
maple
Intermediate
No need to thin.
Moderate
to fast
14-20"
d.h.h.
Sprouts often butt-rotted.
Subject to black heart.
Sprouts vigorously. Seed8
almost every year.
Aspen
Intolerant
No need to thin.
Fast
40-50
years
Rots easily. Large-tooth aspen
is the better species.
Abundant root suckering.
Seeds 4-5 years.
Red
spruce
very
tolerant
Responds to thinnlng or release.
Slow to
moderate
12-18"
d.b.h.
Bhallow rooted.
Seeds 3-8 years.
Responds very well
to release.
Moderate
to fast
16-22"
d.b.h.
Larger trees subject to
ring shake.
Seede 2-3 years.
Eastern
hemlock
Very
-tolerant
'1n preparing
for the species.
this list,
it was assumed
that the
trees are found
Pole trees sprout vigorously. Seeds every 3-7 years.
under favorable growing conditions,
Seeds every
such as site and stocking,
Some Characteristics of
the Northern Hardwoods
SPECIES
K
EY SPECIES i n the northern hardwood f o r e s t a r e yellow
b i r c h (Betula a L leghaniensis), beech (Fagus grandifol ia), and sugar maple (Acer saccharurn). These t h r e e s p e c i e s
may occur together a s a nearly pure f o r e s t type, o r they may
be a s s o c i a t e d w i t h hemlock (Tsuga canadens is), red spruce
(Picea rubens), paper b i r c h (Betula papyrifera) white ash
(Fraxinus americana), r e d maple (Acer rubrum), o r aspen
(Popu lus trernuloides and P. grandidentata). Younger stands
t h a t have f o l l o w e d f i r e o r c l e a r - c u t t i n g , o r t h a t have
seeded i n abandoned p a s t u r e s , o f t e n c o n t a i n l a r g e proport i o n s of paper b i r c h , a s h , red maple, and aspen a s a cover
type
I n t h e management of t h e s e f o r e s t s , t h e c h a r a c t e r i s t i c s of the p r i n c i p a l species (those t h a t a f f e c t t h e i r r e sponse t o c u l t u r a l t r e a t m e n t s ) should be considered ( t a b l e
1).
SITES
In New England, n o r t h e r n hardwood s i t e s occur up t o
e l e v a t i o n s of about 2,000 f e e t , on land t h a t is r o l l i n g t o
mountainous. The r i v e r v a l l e y s below t h e hardwoods a r e
usually occupied by white pine types i n the southern p a r t of
t h e r e g i o n and by spruce and f i r types f a r t h e r n o r t h . I n
the mountains, spruce types grow above t h e hardwoods.
On hardwood s i t e s , t h e land i s u s u a l l y s t o n y . Most
s o i l s a r e podzols or brown pcdzolics derived from g l a c i a t e d
g r a n i t e s and s c h i s t s . A few s o i l s have developed wholly or
i n p a r t from limestone and have b e t t e r s t r u c t u r e and g r e a t e r
f e r t i l i t y than t h e podzols. The most productive but l e a s t
common s o i l s a r e d e e p , w e l l d r a i n e d t o m o d e r a t e l y w e l l
d r a i n e d , and o f medium t e x t u r e .
OLD GROWTH
The t y p i c a l old-growth n o r t h e r n hardwood f o r e s t of
today has a h i s t o r y of some c u t t i n g about t h e t u r n of t h e
century ( f i g . 1). The f i r s t c u t t i n g usually took a l l of the
softwood sawtimber. L a t e r , the b e t t e r hardwoods were c u t .
The larger t r e e s t h a t remain a r e often overmature and of low
value i n terns of species or qua.lity. The smaller sawtimber
t r e e s were present b u t unmerchantable d u r i n g those e a r l i e r
operations; saplings and ~ o l e scame i n l a t e r . Since then,
the s t a n d s may have been untouched.
I n these old-growth f o r e s t s , c u l l - - i n completely usel e s s t r e e s and p o r t i o n s of merchantable t r e e s - - u s u a l l y
amounts t o a t h i r d of t h e gross volume. Growth cmmonly is
slow, and the t r e e s vary considerably i n quality. 'Ihe stands
a r e most often uneven-aged, usually with gaps i n some diarne t e r c l a s s e s and excesses i n o t h e r s . Trees range i n s i z e
Seedlings of
from s a p l i n g s t o more than 30 inches d.b.h.
t o l e r a n t species, such as sugar maple and beech, are abundant.
SECOND GROWTH
Second-growth f o r e s t s a r e more o r l e s s even-aged.
Where areas have been t r u l y c l e a r - c u t f o r charcoal o r f u e l wood, o r burned over, t h e r e is a narrow range of ages and
diameters. Other a r e a s have only been heavily high-graded.
While t h e p r o p o r t i o n of even-aged t r e e s i s high i n t h e s e
s t a n d s , t h e r e i s a s c a t t e r i n g o f l a r g e o l d c u l l o r wolf
trees.
Old-Growth Forest
T H E old-grmvth f o r e s t usually w i l l be managed under an
uneven-aged s i l v i c u l t u r a l system, but some s t a n d s
within the f o r e s t may be t r e a t e d d i f f e r e n t l y . Timber markers
w i l l keep i n mind n o t only t h e s t o c k i n g , s t r u c t u r e , and
growth g o a l s o u t l i n e d i n a l a t e r s e c t i o n but a l s o c u r r e n t
r e a l i t i e s such a s c o s t s and s e l l i n g prices. The recomnendat i o n s t h a t follow a r e s i m i l a r t o those proposed e a r l i e r by
Jensen (3). I n a p p l i c a t i o n , the f o r e s t e r may want t o a l t e r
these recommendations i n l i n e with h i s own experience, t h e
wishes of the property owner, and l o c a l growingand marketing
conditions.
SILVICULTURAL SYSTEMS
Se l e c t ion
System C u t t i n g
S i n c e p a s t c u t t i n g o p e r a t i o n s have downgraded t h e
growing s t o c k , most s t a n d s t h a t a r e t o become p a r t of a
balancecc, uneven-aged f o r e s t need a thorough renovating when
management is s t a r t e d . Nearly always, there is s o m c h poor
growing stock t h a t the f i r s t c u t should be moderately heavy,
t a k i n g 25 t o 40 p e r c e n t of t h e g r o s s volume i n t r e e s 5.0
inches d.b.h. and l a r g e r . Removal of more than 40 percent
of t h e gross volume is n o t u s u a l l y a d v i s a b l e , a s t h e shock
might c a u s e some t r e e s , s u c h a s y e l l o w b i r c h , t o d i e .
Others, a s w e l l a s yellow b i r c h , would tend t o f e a t h e r out
and l o s e value.
The f i r s t c u t o r c u t s a r e p r i m a r i l y f o r res salvage
and improvement. And because most of t h e t r e e s f a l l i n t o
one or more groups of undesirable growing s t o c k , i n a sense,
they "mark themselves". These groups a r e :
Trees t h a t may d i e before the next c u t .
Trees of l o w q u a l i t y and vigor.
Less d e s i r a b l e species.
Multiple stems.
M e r c h a n t a b l e paper b i r c h and a s p e n , p a r t i c u l a r l y a t
maturity.
The s i l v i c u l t u r a l requirement i s t h a t t h e f i r s t c u t
should, a s s t a t e d , be m d e r a t e l y heavy ( f i g . 2 ) . I f the d i s t r i b u t i o n of diameters is d i s t o r t e d , e i t h e r by c u t t i n g o r
o t h e r f a c t o r s , i t w i l l t a k e longer t o r e a c h t h e goal of a
balanced s t r u c t u r e . I n general, any c u t t i n g under the s e l e c t i o n system has t h e combined o b j e c t i v e s of t h i n n i n g , pres a l v a g e , and h a r v e s t c u t t i n g . T h i s i s e s p e c i a l l y t r u e of
f i r s t c u t s i n previously unmanaged f o r e s t s . This combination
of o b j e c t i v e s i n one c u t g i v e s f l e x i b i l i t y i n marking, b u t
r e q u i r e s much s i l v i c u l t u r a l s k i l l .
S t r i c t a p p l i c a t i o n of the t r e e s e l e c t i o n sys tem w i l l
perpetuate or increase t h e proportions of the very t o l e r a n t
species --sugar maple, beech, hemlock, and red spruce.
A primary objective i n any system of moderate c u t t i n g
is improvement of the r e s i d u a l s t a n d . Thus, the removal of
c u l l t r e e s and wolf t r e e s from growing s t o c k is important.
The v a l u e o f a moderate c u t c a n n o t m a t e r i a l i z e w i t h o u t
d i s p o s a l of t h i s i n f e r i o r growing s t o c k . This can be r e moved i n s e v e r a l ways. S a l e s c o n t r a c t s may i n c l u d e provisions f o r f e l l i n g c e r t a i n c u l l t r e e s and a c t u a l o r potent i a l wolf t r e e s . O r , these t r e e s may be g i r d l e d or t r e a t e d
with s i l v i c i d e s a f t e r the c u t t i n g is done.
The s e l e c t i o n system is b e s t f o r those stands where:
Most t r e e s t o be removed occur s i n g l y r a t h e r t h a n i n
groups
.
There a r e ample markets f o r t h e very t o l e r a n t s p e c i e s .
0 The t r e e s reserved f o r f u t u r e growth cover a wide range
of s i z e s and show promise of maintaining or i n c r e a s i n g
t h e i r value.
Patch
Cutting
Patch c u t t i n g s a r e c l e a r - c u t t i n g s of s m a l l a r e a s ,
usually l e s s than 2/3 acre. Those t r e e s within a patch t h a t
a r e n o t harvested a r e g i r d l e d o r poisoned, i n c l u d i n g s a p l i n g s down t o 2 i n c h e s .
I n many old-growth s t a n d s , t r e e s t h a t would be s e l e c t e d f o r c u t t i n g occur i n clumps or groups
These could
be the n u c l e i i of patches. To decide i f they should be enlarged t o patch s i z e , weigh the present and future values of
the a d d i t i o n a l t r e e s t h a t would be c u t a g a i n s t the need f o r
reproduction of the l e s s t o l e r a n t species--yellow and paper
birch.
A t the B a r t l e t t Experimental F o r e s t , yellow b i r c h has
reproduced very w e l l on patches up t o 1/3 a c r e . Regenerat i o n of paper b i r c h has been promising on patches of 1/3 t o
2/3 a c r e . I n l a y i n g out p a t c h e s , we t r y t o avoid l e a v i n g
yellow b i r c h exposed t o the s o u t h and west ( n o r t h and e a s t
s i d e of p a t c h ) because i t is very s e n s i t i v e t o sudden temp e r a t u r e changes.
Clear
Cut ting
In old-growth f o r e s t , some a r e a s may n o t c o n t a i n
enough valuable o r p o t e n t i a l l y valuable s t e m t o hold over
f o r another c u t . These areas should be c l e a r - c u t , including
complete removal of s a p l i n g s and c u l l t r e e s ( f i g . 3 ) . Reg e n e r a t i o n a f t e r such c u t t i n g u s u a l l y is good, comprising
both advance reproduction and new s e e d l i n g s and s p r o u t s .
Paper b i r c h , yelluw b i r c h , and aspen t y p i c a l l y appear i n the
new regeneration i n g r e a t e r proportion than i n the previous
stand.
01both patch and c l e a r - c u t t i n g s , t h e r e a r e small unmerchantable t r e e s a s well a s l a r g e c u l l t r e e s t h a t should
be removed. A s i n t h e s e l e c t i o n system, t h e s e c o u l d be
f e l l e d during logging. O r , they could be g i r d l e d or t r e a t e d
with s i l v i c i d e s soon a f t e r .
I n t h e t y p i c a l o l d - g r o w t h . f o r e s t , t h e r e is o f t e n a
need f o r a l l t h r e e methods of c u t t i n g - - s e l e c t i o n , patch, and
clear-cutting.
For a g i v e n a r e a w i t h i n t h e f o r e s t , t h e
choice depends upon the condition of t h e s t a n d i n g t r e e s and
the need f o r regeneration of c e r t a i n species. The s e l e c t i o n
system w i l l find the most general use, with occasional patch
c u t t i n g s where the t r e e s t o be removed occur i n groups. The
need f o r c l e a r - c u t t i n g is l e a s t frequent.
STOCKING, STRUCTURE, AND GROWTH
Regardless of product o b j e c t i v e s , hardwood f o r e s t s
w i l l always produce much material s u i t a b l e only f o r pulpwood
and other bulk products. When the old-growth f o r e s t is put
under management, t h e f i r s t c u t s u s u a l l y w i l l be low i n
value because of c u l l and poor c p a l i t y . Even l a t e r , when
the f o r e s t is on s u s t a i n e d y i e l d under some uneven-aged s i l v i c u l t u r a l system, t h e r e w i l l be periodic harvests of smalle r t r e e s . And upper s e c t i o n s of sawlog t r e e s w i l l continue
t o be lower i n q u a l i t y than b u t t s . T h e r e f o r e , one cannot
Table 2.--Estimated
r e s i d u a l s t r u c t u r e and wowth ~ o a l sper acre1
f o r uneven-axed n o r t h e r n hardwoods m a n a ~ e df o r
b i ~ h - v a l u e dproducts
basal area3
Cu.ft.
acre.
Bd.ft.
' ~ b i s- d e s i r e d s t o c k i n g and s t r u c t u r e a f t e r each c u t r e p r e s e n t s t h e average
I t i s n o t expected t h a t each a c r e w i l l e v e r conform r i g i d l y t o t h e s e g o a l s .
I t 16 t h e growth of a l l t r e e s of
2 ~ r o d u c t i o nis t h e n e t change i n volume.
measurable s i z e p r e s e n t a f t e r c u t t i n g , minus m o r t a l i t y , p l u s ingrowth.
3 ~ rough
s
conversion f a c t o r s f o r p a l e t i m b e r , r e use 5 s q u a r e f e e t of b a s a l
a r e a f o r a rough cord and 20 cubic f e e t f o r a square f o o t .
F o r sawtimber, we use
4 s q u a r e f e e t of b a s a l a r e a p e r c o r d , 25 c u b i c f e e t p e r s q u a r e f o o t of b a s a l a r e a .
and 120 b o a r d - f e e t p e r s q u a r e f o o t .
NUMBER OF TREES PER ACRE
BASAL A'REA PER
ACRE (SQUARE F E E T )
Figure 4.--Suggested s t a n d and stocking
f o r unevenraged n o r t h e r n hardwoods
a f t e r each c u t t i n g , f o r h i g h - v a l u e
products.
manage only f o r high-value m a t e r i a l such as veneer and saw
logs. Management g o a l s must be c o n s i s t e n t w i t h (1) t h e
c h a r a c t e r i s t i c s of t h e s p e c i e s , ( 2 ) . t h e s i t e s upon which
t h e y grow, and ( 3 ) t h e systems of s i l v i c u l t u r e f o r which
they a r e s u i t e d .
High- Va lue
Products
Hardwoods on average - t o - b e t t e r s i t e s t h a t a r e reasona b l y a c c e s s i b l e c a n be managed p r i m a r i l y f o r h i g h - v a l u e
products. In uneven-aged f o r e s t s , t h e l a r g e s t y i e l d s of
high-value p r o d u c t s a r e a s s o c i a t e d w i t h r e l a t i v e l y l a r g e
volumes per a c r e . This is s o because a l a r g e proportion of
the growing stock is in large t r e e s (5). This i n t u r n means
fewer t r e e s t o the acre ( t a b l e 2).
Table 3.--Estimated residual structure and growth goals per acre1
for uneven-aged northern hardwoods mana~ed for bulk products
Diameter
class &
group
Stand and stocking
Trees
Number
Sq.ft.
Estimated annual
production,
basal area2
Estimated allowable
cut in 10 years
Sq.ft.
Cu.ft.
Bd.ft.
58
64
64
70
60
50
38
--
8
7
5
0.29
.32
.32
.28
.24
.20
.15
336
288
240
180
130
60
1.80
404
1,044
6-10
12-14
16-18
100
20
10
31
17
12
0.93
.52
.35
186
130
88
624
420
Total
130
60
1.80
404
1,044
6
8
10
12
14
16
18
50
30
20
12
8
6
4
10
11
10
Total
9
---
--
his
acre.
desired stocking and structure after each cut represents the average
It is not expected that each acre rill ever conform rigidly to these goals.
2 ~ e etable 2, footnotes 2 and 3.
To manage f o r these products, we recommend a stocking
of about 80square f e e t of basal area per a c r e a f t e r c u t t i n g ,
i n t r e e s from5.0to 25.0 inches d.b.h. ( t a b l e 2 and f i g . 4).
This corresponds t a about 1 , 9 0 0 cubic f e e t per a c r e , t o a
f l e x i b l e 4-inch t o p diameter.
In t a b l e 2, w e have used three diameter groups, based
upon 2-inch d.b.h. classes. I f other diameter groupings a r e
d e s i r e d , the required numbers of t r e e s can be read from t h e
table. Regardless of e x i s t i n g stocking, the g r e a t e s t potent i a l lies in the large sawtimber group. Only a few t r e e s i n
the middle group w i l l m k e Factory Grade 1 logs (8).
'
Growth estimates, drawn from experience a t B a r t l e t t ,
i n d i c a t e t h e volumes and s i z e s of t r e e s expected t o be
a v a i l a b l e f o r subsequent c u t s under s i m i l a r conditions. In
'This refers to U.S. Forest Service hardwood log grades for standard lumber. In general, No. 1 logs will yield from 64 to S O percent No. 1 common and
better lumber; No. 2 logs, 40 to 64 percent; No. 3 logs, 13 to 3 6 percent. The
variation is due chiefly to differences in species and log diameters.
a d d i t i o n t o growth, t h e a l l o w a b l e c u t depends upon t h e
length of t h e c u t t i n g cycle.
We recommend c u t t i n g c y c l e s of 10 t o 20 y e a r s f o r
most conditions. Present stocking, a c c e s s i b i l i t y , markets,
and volume a l l i n f l u e n c e t h e length of c u t t i n g c y c l e . With
cycles longer than 20 years, however, t h e r e is l e s s c o n t r o l
over growth r a t e , m o r t a l i t y , c u l l , and reproduction.
We do not mean t h a t every acre must have t h e d e s i r e d
s t o c k i n g and s t r u c t u r e . These goals may not be approached
f o r s e v e r a l c u t t i n g cycles. But when most acres i n the f o r e s t come c l o s e t o t h i s s t o c k i n g and s t r u c t u r e , i t w i l l be
p o s s i b l e t o have s t a b l e , s u s t a i n e d c u t s . And most of the
allowable sawtimber c u t w i l l come from l a r g e r t r e e s .
Of course, s p e c i e s i s a t l e a s t a s important a s t r e e
s i z e i n determining product v a l u e s . Within t h e l i m i t s of
t h e d e s i r e d s t o c k i n g and s t r u c t u r e , t h e f o r e s t e r can mold
the species composition over s e v e r a l c u t s by h i s c u t t i n g and
c u l t u r a l p r a c t i c e s . In the uneven-aged f o r e s t s , we want t o
maintain or i n c r e a s e t h e proportions of y e l l a v b i r c h , sugar
maple, red s p r u c e , and hemlock.
1
FOR
BULK
PRODUCTS
BASAL AREA PER
ACRE (SQUARE F E E T )
Figure 5. --Suggested stand and stocking for unevenaged northern hardwoods after each cutting, for
bulk products.
13
Bulk
Products
-
0-1poorer s i t e s , hardwoods should be managed primar i
l y f o r b u l k p r o d u c t s ; b u t even on t h e b e t t e r s i t e s S ~
owners may prefer t o manage f o r such products. Poorer s i t e s
a r e g e n e r a l l y d r i e r or c l o s e t o t h e upper l i m i t s f o r hardwood timber on mountain slopes. There a r e no d e f i n i t ive hardwood-site-productivity d a t a f o r t h i s region. S t i l l , we can
assume t h a t on poorer s i t e s t h e mature hardwoods average
l e s s than 30 f e e t i n merchantable height t o a 4-inch top.
For b u l k p r o d u c t s we recommend a s t o c k i n g o f 60
square f e e t of b a s a l a r e a a f t e r c u t t i n g i n t r e e s 5.0 inches
t o 18.0 inches d.b.h. ( t a b l e 3 and f i g . 5). With t h i s stand
s t r u c t u r e and l e v e l of stocking, much growth w i l l be i n poletimber, and most products c u t w i l l be s m a l l . I n g e n e r a l ,
c u t t i n g c y c l e s w i l l be 20 y e a r s longer.
Second-Growth Farest
S
ECOND GROWTH f o r e s t s have a s m a l l e r range of s i z e
c l a s s e s t h a n o l d growth. But q u a l i t y may v a r y a s
widely. Some s t a n d s may be f i l l e d with aspen and r e d maple
s p r o u t s ; o t h e r s w i l l c o n t a i n a h i g h p r o p o r t i o n of paper
b i r c h and w h i t e a s h . Among t h e second-growth hardwoods,
w h i t e a s h and paper b i r c h a r e most d e s i r e d , w i t h y e l l o w
b i r c h and sugar maple next i n rank.
Second-growth f o r e s t s w i l l u s u a l l y be handled by an
even-aged s i l v i c u l t u r a 1 system. S i n c e t h e t r e e s a r e young
and s m a l l , and mature r e l a t i v e l y e a r l y , s i l v i c u l t u r a l s y s t e m must be concerned w i t h reproduction a f t e r c u t t i n g .
SILVICULTURAL SYSTEMS
Clear
Cutting
Based upon observations a t B a r t l e t t (10) and elsewhere
i n New England, t h e p r a c t i c e of c l e a r - c u t t i n g e x t e n s i v e
E
a r e a s of second growth may n o t provide s a t i s f a c t o r y r e p r o d u c t i o n . O f t e n , s u c h c u t t i n g i s f o l l o w e d by r a s p b e r r y ,
b l a c k b e r r y , and p i n c h e r r y . When t h a t happens, i t may be
many years b e f o r e merchantable t r e e s p e c i e s take over. A t
l e a s t , t h i s appears t r u e now where s t a n d s under 60 years of
age have been c l e a r - c u t on a r e a s l a r g e r than 1 a c r e .
Though t h e s e o b s e r v a t i o n s a r e n o t backed up by e x perimentation, t h e r e is l i t t l e doubt about t h e r e s u l t s of
successive c l e a r - c u t t i n g s of young, even-aged s t a n d s i n New
York and Pennsylvania. They have led t o stand d e t e r i o r a t i o n :
l e s s d e s i r a b l e s p e c i e s , more s p r o u t growth, s m a l l e r y i e l d s ,
and a general lowering of s t a n d q u a l i t y .
C l e a r - c u t t i n g of s t r i p s not more than 2 chains wide
o r i n patches of l e s s than 1 a c r e i n a r e a rmay be s u c c e s s f u l
i n obtaining reproduction of d e s i r a b l e s p e c i e s ( f i g . 6).
I n s t e a d of a s i n g l e c l e a r - c u t t i n g i n t h e young
second-growth f o r e s t , t h e r e may be one or more i n t e r i m c u t s
before r o t a t i o n age is reached (9). These operations would
be a combination of improvement and h a r v e s t c u t s . T h i s i s
s o because of t h e e a r l y s i l v i c a l and economic m a t u r i t y of
aspen, paper b i r c h , and white a s h .
Aspen t e n d s t o break up a t age 50. Paper b i r c h may
be r i p e a t 60 y e a r s , A f t e r 70 y e a r s , i t w i l l begin t o d e t e r i o r a t e , and t h e r a t i o of d e s i r a b l e sapwood w i l l decrease.
Probably a s h w i l l have accilmulated i t s maximum of v a l u a b l e
sapwood a t 80 y e a r s . Thus, depending upon t h e age and comp o s i t i o n of the s t a n d s , any i n t e r i m c u t s w i l l include a h a r v e s t of one or more of t h e s e s h o r t - l i v e d s p e c i e s . A t t h e
same t i m e , f o r improvement c u t t i n g , t h e f o r e s t e r may mark
r e d maple s p r o u t clumps and beech and s u g a r maple stems of
low v i g o r o r q u a l i t y .
As a r e s u l t of t h i s type of o p e r a t i o n , s t a n d d e n s i t y
is r e d u c e d , t h e crown canopy is b r o k e n , and r e p r o d u c t i o n
d e v e l o p s . Then, when t h e s t a n d r e a c h e s 80 y e a r s o r o l d e r ,
the o v e r s t o r y c a n be removed by a s e r i e s of c l e a r - c u t s . As
i n t h e old-growth f o r e s t , t h e composition of t h e r e s u l t i n g
s t a n d w i l l be i n f l u e n c e d by t h a t of t h e o v e r s t o r y a t t h e
time of t h e f i n a l c l e a r - c u t , t h e advance growth, and t h e
s i z e s of t h e o p e n i n g s ( 4 ) .
Selection
System Cutting
The f o r e s t e r has an a l t e r n a t i v e t o the even-aged s y s tem of s i l v i c u l t u r e r e p r e s e n t e d by c l e a r - c u t t i n g and s h e l t e r wood c u t t i n g : i f w i l l i n g t o move toward t h e c l a s s i c climax
t y p e of b i r c h - b e e c h - m a p l e , he may c u t u n d e r t h e s e l e c t i o n
system. A f t e r s e v e r a l s e l e c t i o n c u t s i n second-growth f o r e s t s , t h e p r o p o r t i o n of more t o l e r a n t hardwoods should have
i n c r e a s e d (9). With c o n t i n u e d c u t t i n g under t h e s e l e c t i o n
system, s t r u c t u r e w i l l change from even-aged t o uneven-aged.
I n d e c i d i n g upon a s y s t e m of s i l v i c u l t u r e f o r t h e
second-growth hardwood f o r e s t , t h e d e s i r e d c o m p o s i t i o n of
t h e r e g e n e r a t i o n i s t h e prime c o n s i d e r a t i o n . The v a r i o u s
t y p e s of c l e a r - c u t t i n g - - b l o c k s , s t r i p s , p a t c h e s , s h e l t e r wood--will f a v o r t h e less t o l e r a n t a s h and b i r c h e s . The
s e l e c t i o n system favors sugar maple, beech, and hemlock.
TENDING THE STANDS
I n a d d i t i o n t o manipulation of merchantable c u t s , t h e
f o r e s t e r has a number of s i l v i c u l t u r a l t o o l s f o r improving
young even-aged f o r e s t s . These t o o l s o r treatments - - c h i e f l y
c l e a n i n g s and t h i n n i n g s - - a r e used t o i n c r e a s e timber q u a l i t y
and v a l u e y i e l d d u r i n g t h e r o t a t i o n .
I n some c a s e s , t h e
r e s u l t s a r e i n d i r e c t . Often they d o not show f o r many y e a r s ,
thus making the t r e a t m e n t s d i f f i c u l t t o e v a l u a t e .
Cleaning is an o p e r a t i o n i n which u n d e s i r a b l e members
of j u v e n i l e or s a p l i n g s t a n d s a r e removed (7). These include
t r e e s o f u n m e r c h a n t a b l e o r low-value s p e c i e s , f o r k e d o r
crooked t r e e s , and stump s p r o u t s i n t h e main crown canopy.
We have no experimental d a t a on t h e n e t b e n e f i t s of c l e a n i n g
young hardwood s t a n d s . It seems obvious t h a t , i n t h e long
r u n , c! ..aning s h o u l d a p p r e c i a b l y i n c r e a s e s t a n d v a l u e - - b u t
we d o n ' t . know how much. A t p r e s e n t , we recommend c l e a n i n g
t o t h o s e who a r e w i l l i n g t o i n v e s t i n b r i n g i n g through t o
pole s i z e maximum numbers of s a p l i n g s of d e s i r e d s p e c i e s and
form.
C l e a n i n g s s h o u l d be begun when t h e t r e e s a r e head
high--no more than 1.0 years of ape--and should be continued
u n t i l t h e t r e e s r e a c h p o l e s i z e . C l e a n i n g s s h o u l d be s o
l i g h t t h a t i t is d i f f i c u l t t o s e e t h a t t h e s t a n d h a s been
touched, and should be r e s t r i c t e d t o t h e main crown canopy.
S a p l i n g s t a n d s always should be dense enough t o ensure s e l f pruning of lower limbs, s t r a i g h t n e s s of b o l e , and a minimum
of snow and i c e damage. C l e a n i n g s s h o u l d he r e p e a t e d a s
o f t e n a s needed t o m a i n t a i n a h e a l t h y , v i g o r o u s s t a n d of
des i r a h e stems.
Removal of s a p l i n g a s p e n and p i n c h e r r y may n o t be
n e c e s s a r y . The f o l i a g e of a s p e n and p i n c h e r r y is l i g h t
enough n o t t o unduly h i n d e r t h e growth o f o t h e r s p e c i e s .
Pin c h e r r y d i e s out of the s t a n d a t an e a r l y age. And t h e r e
may be markets f o r the l a r g e r aspen, which would then be t h e
f i r s t crop.
Most young, even-aged n o r t h e r n hardwood s t a n d s c a n
b e n e f i t from j u d i c i o u s t h i n n i n g . While t h e r e a r e s e v e r a l
methods of t h i n n i n g , crown o r c r o p - t r e e t h i n n i n g s seem b e s t
f o r t h e s e s t a n d s ( 2 ) . I n g e n e r a l , t h e time t o s t a r t t h i n n i n g
i s a s soon a s c r o p t r e e s can be recognized. S t a n d s of i n t o l e r a n t s p e c i e s , s u c h a s paper b i r c h , s h o u l d he t h i n n e d
e a r l i e r than those of t o l e r a n t s p e c i e s . Before age 40, paper
b i r c h and w h i t e a s h may respond t o t h i n n i n g , b u t a c c o r d i n g
t o our d a t a t h e y d o n o t respond a f t e r age 60. Sugar maple
and t h e o t h e r t o l e r a n t s p e c i e s , however, w i l l respond even
a f t e r age 60.
I n a c r o p - t r e e t h i n n i n g , only t r e e s t h a t a r e i n t e r f e r i n g with t h e c r m n development of c r o p t r e e s a r e removed.
S t i l l , t y p i c a l s t a n d s c o n t a i n poor growing s t o c k i n t h e main
crown canopy t h a t may not be i n t h e way of t h e c r o p t r e e s .
They may be c u t i f 2 :
Growth w i l l be s h i f t e d t o b e t t e r t r e e s , o r
They may n o t l i v e t o t h e next t h i n n i n g , or
'Ihe s t a n d w i l l n o t be opened e x c e s s i v e l y , or
'Ihe r e d u c t i o n i n s t a n d d e n s i t y w i l l f a c i l i t a t e regeneration later.
Although p r e c i s e s t a n d - d e n s i t y g u i d e l i n e s a r e n o t
a v a i l a b l e , t h i n n i n g s s h o u l d b e heavy enough t o e n s u r e a
s t e a d y increase i n the volume and value growth of t h e b e t t e r
t r e e s i n the s t a n d . I n d i c a t i o n s a r e t h a t it is b e s t t o t h i n
l i g h t l y and o f t e n ; i n t e r v a l s of 10 t o 15 y e a r s i n n o r t h e r n
hardwoods should g i v e t h e f o r e s t e r r e a s o n a b l e c o n t r o l over
t h e s t a n d ' s development. E x c e s s i v e opening of t h e crown
canopy may r e s u l t i n a " f e a t h e r i n g o u t " of t h e t r e e s , w i t h
a p o s s i b l e lass of v a l u e . Yellow b i r c h is e s p e c i a l l y s e n s i t i v e t o e x c e s s i v e crown openings.
Should t h e t h i n n i n g pay f o r i t s e l f ? S i n c e t h e t r e e s
removed w i l l be s m a l l o r rough, t h e i r v a l u e w i l l be low.
A more c r i t i c a l q u e s t i o n i s : " W i l l t h e i n c r e a s e i n v a l u e
y i e l d d u r i n g t h e r o t a t i o n , a s compared t o an unthinned s t a n d ,
be more than enough t o pay f o r t h e thinnings ?" T h i s mst be
answered on t h e land i t s e l f ; b u t i f t h e work i s well-timed
and well-done t h e answer s h o u l d be "yes".
Red maple ' s p r o u t clumps a r e o f t e n a problem. A t
B a r t l e t t , we have t r i e d c u t t i n g one o r two s p r o u t s from a
clump. But growth d i d not i n c r e a s e on t h e remaining s p r o u t s ,
and h e a r t r o t s p r e a d t o some of them. Now, w e a d v i s e c u t t i n g t h e e n t i r e clump. S i l v i c i d e s can be used t o prevent r e s p r o u t i n g . Large hold-overs can be removed w i t h t h e t h i n -
'~rorn l e c t u r e n o t e s of Hans Leibundgut, p r o f e s s o r o f s i l v i c u l t u r e a t t h e
Swiss Federal I n s t i t u t e O F Technology, Zurich, Switzerland.
n i n g s o r they can be g i r d l e d o r poisoned i n a s e p a r a t e
operation.
Thinnings .recommended here a r e n o t t o be confused
w i t h t h e i n t e r i m c u t s i n second-growth s t a n d s mentioned
e a r l i e r . Here, w e a r e dealing with a planned s e r i e s of cuts
aimed a t increasing t h e t o t a l volume and value y i e l d of the
stand during the r o t a t i o n (2).
ROTATION AND STOCKING
Product o b j e c t i v e s f o r t h e second-growth n o r t h e r n
hardwood f o r e s t may be q u i t e f l e x i b l e . They a r e a function
of species composition, growing stock l e v e l , length of r o t a t i o n , and owner preference.
High-Va lue
Products
Even-aged , second-growth f o r e s t s , especially those on
good s i t e s , can y i e l d high-value products. Where the species
a r e mostly yellow b i r c h , beech, and sugar maple, high-value
y i e l d s w i l l be a s s o c i a t e d with long r o t a t i o n s (100 t o 120
y e a r s ) and a h i g h l e v e l of s t o c k i n g a f t e r t h i n n i n g ( 8 0
square f e e t of basal a r e a ) , with fewer t r e e s t o the a c r e a s
r o t a t i o n age approaches ( 6 ) . Stands t h a t c o n t a i n a h i g h
proportion of t h e l e s s t o l e r a n t species--aspen, red maple,
paper b i r c h , and white ash--can be managed on an 80-year
r o t a t i o n a t about 70 s q u a r e f e e t of b a s a l a r e a p e r a c r e
a f t e r each thinning. Most of t h e white a s h would be held
for the f i n a l cut.
To r e a l i z e maxirmun values from second-growth s t a n d s ,
there would have t o be a s e r i e s of thinnings and improvement
treatments before the harvest c u t s . I n some s t a n d s , these
thinnings would i n c l u d e a h a r v e s t c u t of paper b i r c h and
white ash, which o f t e n make f u r n i t u r e s q u a r e s and handle
stock.
~
We have yet t o c a r r y a stand a t the B a r t l e t t through
a r o t a t i o n with a high-value product o b j e c t i v e . However,
t h i s has been done s o o f t e n and s o s u c c e s s f u l l y with beech
and oak i n Denmark, France, Germany, and o t h e r c o u n t r i e s ,
t h a t it should be p o s s i b l e i n New England.
Bulk
Products
The o b j e c t i v e h e r e is maximum volume y i e l d s of such
products a s pulpwood, chemical wood, and fuelwood. Thinning
would serve only t o harvest t r e e s t h a t would otherwise d i e ,
or t o maintain mast of the volume i n t r e e s of a t l e a s t minimum merchantable s i z e . Since bulk products c m o n l y a r e law
i n value, investments i n c u l t u r a l p r a c t i c e s must be kept low.
I n general, poorer s i t e s and l e s s a c c e s s i b l e a r e a s would be
managed f o r bulk products. For these s i t e s and t h i s product
o b j e c t i v e , we recommend a s t o c k i n g of 60 s q u a r e f e e t of
b a s a l a r e a p e r a c r e w i t h a 60-year r o t a t i o n .
General Remarks
I
N general, previous l y unmanaged northern hardwood f o r e s t s
in New England can be divided i n t o two types: old growth
and second-growth.
Each c a l l s f o r d i f f e r e n t treatment.
As old-growth is put under management, it w i l l probably be converted t o a balanced, uneven-aged f o r e s t . Flexible
methods a r e suggested f o r c o n v e r t i n g the old-growth f o r e s t
t o t h i s managed s t a t e and holding i t t h e r e . The suggested
mximum diameters a r e not meant t o be taken a s the l a s t word.
Should a s t a n d c o n t a i n l a r g e r , high-value t r e e s t h a t a r e
t h r i f t y , it would be unwise t o l i q u i d a t e a l l of them a t once.
Other s t a n d s may n o t have any t r e e s l a r g e r than 20 inches.
It would take many years t o r a i s e t h e i r maximum diameter 4
inches. I n balanced, uneven-aged f o r e s t s , a change i n t h e
upper-diameter l i m i t of only 2 inches has a profound e f f e c t
upon the t o t a l volume and, perhaps, upon t h e q u a l i t y of t h e
trees.
A s second-growth i s put under management, i t w i l l
u s u a l l y become an even-aged f o r e s t . But, the concept of a
r o t a t i o n i n n o r t h e r n hardwoods is not hard and f a s t . For
t h e f i r s t $0 or 60 y e a r s , t h e r e w i l l be a narrow range of
ages and diameter c l a s s e s . S k i l l f u l management w i l l include
thinnings , and h a r v e s t i n g of early-maturing s p e c i e s . Thus,
w i t h i n c r e a s i n g a g e , t h e composition w i l l include more of
t h e t o l e r a n t s p e c i e s w i t h a g r e a t e r range of s i z e s . And,
t h e r e w i l l be advance reproduction of t h e t o l e r a n t s p e c i e s .
For long r o t a t i o n s t h i s means t h a t a s liquidation-age nears,
t h e f o r e s t w i l l look l e s s even-aged. The f o r e s t e r working
with s h o r t r o t a t i o n s probably w i l l not run i n t o t h i s s i t u a tion.
We have assumed t h a t t h e g e n e r a l p r e c e p t s of good
f o r e s t management w i l l be followed. This means adequate
p r o t e c t i o n , r e c o g n i z i n g m u l t i p l e - u s e v a l u e s , and d i v i d i n g
the f o r e s t i n t o compartments o r c h a n c e s w i t h permanent
boundaries ; i t is important t h a t the boundaries be permanent.
Product objectives, stocking and s t r u c t u r e goals, and grawth
volume measurements w i l l a l l be on a compartment b a s i s .
This a p p l i e s a l s o t o records, without which t h e r e can be no
purposeful f o r e s t mnagement
.
Now, i n managing t h e compartments t o conform t o obj e c t i v e s , t h e f o r e s t e r may t r e a t s e v e r a l d i f f e r e n t s t a n d s
w i t h i n t h e compartment. I n o t h e r words, concepts such a s
s t a n d s , p a t c h e s , openings, and s t r i p s a r e r e l a t e d t o t h e
s i l v i c u l t u r a l t o o l s t h a t t h e f o r e s t e r uses i n managing t h e
compartment and t h e f o r e s t . For small ownerships, t h e comp a r t m n t and t h e f o r e s t may be one. But the g u i d i n g p r i n c i p l e s a r e t h e same.
The suggestions made here a r e f o r general f o r e s t cond i t i o n s . Smaller areas (such a s woodlots) t h a t a r e more acc e s s i b l e and c l o s e r t o good markets, may be managed more
i n t e n s i v e l y t h a n l a r g e r , more remote f o r e s t s . T h i s means
s h o r t e r c u t t i n g c y c l e s , more growing s t o c k p e r a c r e , and
more t imber-stand-improvement a c t i v i t i e s .
1. Hawley, Ralph C., and Smith, David M.
1954. The practice of s i l v i c u l t u r e . Ed. 6.
525 pp., i l l u s . New York.
2. Heiberg, Svend 0.. and Haddock, Philip G.
1955. A mthod of thinning and forecast of yield i n
Douglas fir. Jour. Forestry 53: 10-18.
3.
Jensen, Victor S.
1943. Suggestions f o r the menagement of northern
J a r . Forhardwood stands in the Northeast.
e s t r y 41: 180-185.
4 . Leak, William B . . and Wilsm, Robert W., J r .
1958. Regeneration a f t e r c u t t i n g of old-growth northe r n hardwoods i n New Hamphire.
Northeast.
Forest Expt. S t a . , S t a . Paper 103. 8 pp.
5.
k y e r , H. Arthur.
1952. Structure, gravth,
even-aged f o r e s t s
.
and drain i n balanced, unJ m r . Forestry 50: 85-92.
6.
Moller, C a r l Mar. e t a l .
1954. Thinning problems and practices i n Denmark.
S t a t e Univ. N. Y.
Edited by Svend 0. Heiberg.
Coll. Forestry Tech. Bul, 76. Syracuse. 92 pp.
7.
Schaede l i n , Walter
1942. Die Aus lesedurchforstung.
147 pp., i l l u s . Berne, Switzerland.
8.
U.S. Forest Products Laboratory.
1953. Hardwood log grades f o r standard lum5er Proposals, and r e s u l t s .
Forest Prod. Lab. Rpt.
D1737. 15 pp.
9.
Wilson, Robert W., J r .
1953. How second-growth northern hardwoods develop
Northeast. Forest h p t . S t a . ,
a f t e r thinning.
S t a . Paper 62. 12 pp.
10.
.
- -- -- - - -- 1954.
and Jensen, Victor S.
Regeneration a f t e r c l e a r - c u t t i n g second-growth
northern hardwoods.
Northeast. Forest Expt.
S t a . Forest Res. Note 27. 3 pp.
SOME SUGGESTED READING
h b o g a s t , Carl. J r .
1953. Managing northern hardwoods i n the Lake S t a t e s .
Lake S t a t e s Forest Expt. Sta. Misc. Rpt. No. 23,
11 PP.
Eyre, F.H., and Z i l l g i t t , W.M.
1953. P a r t i a l cuttings i n northern hardwoods i n the
Lake S t a t e s .
Lake S t a t e s Forest Ekpt. Sta.
Tech. Bul. No. 1076, 124 pp.
Gilbert, Adrian M.
1954. What is t h i s thing c a l l e d growth?
Northeast. Forest Expt. S t a . , Sta. Paper No. 71,
5 PP.
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Wilson, Robert W., Jr., and Hutnik, Russell J.
1955. Gravth behavior of northern hardwoods a f t e r a
p a r t i a l cutting. J a r . Forestry 53: 488-492.