180.
:

—~ 150-4

100+

505

BASAL AREA PER ACRE (ft”

MEAN STAND DIAMETER linches|

MIXEDWOOD

T
230 460

690
TREES PER ACRE

T T

920 1150

Figure 7.—Stocking guide for main crown canopy of mixedwood stands (25 to 65
percent softwoods) shows basal area and number of trees per acre and quadratic
mean stand diameter. The A line is fully stocked, the B line is suggested residual

stocking, the C line is minimum stocking.

near the mixedwood A line for stands with a mean stand
diameter less than 6 inches.

Growth, Yield, and Rotation

Board-foot and cubic-foot volumes per acre for unmanaged
hardwood stands are given in Table 8, based on simulation
(Solomon and Leak 1985). These are gross yields with no
deduction for cull or defect. Cubic volumes of mixedwood
are at least 15 to 25 percent greater than hardwood yields,
and board-foot volumes may be proportionately even
greater. However, precise estimates of mixedwood yields
are not yet available. Yields of intensively managed hard-
wood stands are simulated in Table 9. These yields are for
stands kept at 80 ft? or more of basal area until the mean
stand d.b.h. reached 6 inches, and then thinned to B-line
density when stand basal area was about two-thirds the

18

distance from B line to A line. Hardwood yields represent
the maximum attainable under intensive silviculture in a
natural stand and total managed yields at about 100 years
of age are 50 to 90 percent greater than unmanaged
yields. In applying both the managed and unmanaged yield
tables, deductions from gross yields must be made for
sound and rotten cull, logging waste, poor stocking, and
nonforest acreage.

The site indexes in Tables 8 and 9 are for sugar maple,
base age 50. Sugar maple sites of 70 and above commonly
occur in New England on soils enriched by organic matter
or derived from rich bedrock (e.g., limestone) or alluvium:
Sugar maple and ash are common on such sites. Sites of
60 to 70 typically are beech-birch-maple sites; the soils are
well- to moderately well-drained, fine-textured tills. Sites of


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35


1, Cull Removal: Culls to be removed should be designated
during marking. Residual culls should be included in
defining the residual basal area and structure—because
they influence growth, regeneration, and quality devel-
opment. Elimination of understory culls is of doubtful
value because of their abundance, slow growth, and
high mortality. Keep in mind the importance of reserving
some cull trees, especially the large ones, for wildlife.
More than 30 species of birds and 20 mammals use
culls in New England for feeding, nesting, or denning.

2. Two-Inch Removal: When group selection is applied,
and the saplings or small poles within a group are of
undesirable species or quality, complete stem removal
down to about 2 inches d.b.h. is recommended. Gener-
ally, this is most easily done during the logging opera-
tion, though a separate postlogging treatment also is
possible using chemical or mechanical methods.

3. Group Stand Improvement: Groups of saplings or small
poles resulting from previous group-selection cuttings
may be dominated by stems of low-quality or undesir-
able species. If less than about 40 percent of the
overstory stems are minimally acceptable, consider a
noncommercial weeding/cleaning to be carried out in
the substandard groups. This work is expensive and
should be restricted to those instances where the site is
good and a marked increase in stand value will result.
The operation should be the minimum required to create
an overstory with at least 40 to 50 percent of the stems
in acceptable species and quality.

Regeneration

Under single-tree selection, more than 90 percent of the
regeneration will be tolerant species. Under group selec-
tion, based on groups averaging about one-half acre in size
with all stems larger than 2 inches removed, about one-
third of the regeneration will be of intermediate or intolerant
species (Table 7). In larger groups up to about 2 acres in
size, the intolerant and intermediate species should
account for one-half of the regeneration. Limited experi-
ence indicates that the proportion of intolerants (e.g., paper
birch) may equal the proportion of intermediates in groups
two-thirds of an acre or larger in size.

Species composition of the regeneration under single-tree
selection is closely related to the advance regeneration.
Areas to be regenerated to sugar maple or sOftwoods
should show evidence of these species in the existing
advance regeneration. To be considered well established, a
hardwood or hemlock stem should be 3 to 4 feet tall; a
‘spruce or fir, about 1 foot tall

Under group selection, the presence of residual tolerant
stems in the seedling, sapling, or small-pole sizes will limit

Table 7.—Species composition of stocked mil-
acres, 10 to 15 years after cutting in
beech-birch-maple stands, by tolerance
group and cutting method

Tolerance Group Single-tree
group* Clearcutting selection selection
wot eee -Percent- ~
Tolerant 43 62
intermediate 19 34
Intolerant 38 4

“Tolerant: beech, sugar maple, eastern hemlock, and
red spruce (also balsam-fir if present); intermediate: yel-
low birch, white ash, and red maple; intolerant: paper
birch and aspen.

intolerant or intermediate regeneration. In regenerating
birch under group selection, advanced regeneration larger
than 2 inches d.b.h. should be sparse, or it should be
removed in creating the opening (Fig. 3). Snow-free logging
generally is more effective than winter logging in reducing
unwanted advanced growth.

Group openings in poletimber stands do not always regen-
erate well—especially on sites that are extremely wet or
dry—and are not recommended. Regeneration in groups
receives more snow damage than in clearcuttings, appar-
ently due to the extra snow that drifts into small canopy
openings. But research has indicated that less than 10
percent of the groups in hardwood and mixedwood stands
were in poor condition due to snow damage.

Border-tree quality is a consideration in group selection
because border trees may tend to retain live limbs or pro-
duce epicormic sprouts. Poles or small sawtimber of hard-
wood species should not be left as border trees without
trainers or buffer trees if they have (1) clear boles but small
live crowns; or (2) lower live limbs that will seriously detract
from quality if allowed to persist. White ash and paper birch
are least likely to produce epicormic sprouts, but live limbs
on any hardwood or softwood species will remain alive for
a substantial period of time if exposed to full sunlight.

What constitutes adequate stocking in the seedling and
sapling size classes of an uneven-aged stand? This ques-
tion has not been answered completely for New England
hardwood and mixedwood stands. However, in extensively


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Appendix

Table 17.—Cumulative percent crown cover for sugar and red
maples, yellow and paper birches, 10-factor prism

D.b.h. Tree count
(inches) “J 23 4) «dS SCOGCtSt=<‘C!;”;*~CS:*C«‘CSCSAASSCi‘«dKD:

2 59 «119
4 28 57 85 114
6 21 41 62 82 103

8 17 34°51 68 84 101
10 15 30 44 59 74 89 103
12 13° 27 40 53 67 80 93 106
14 12 24 37 49 61 73 86 98 110
16 YW 23° 34 45 57 68 80 91 102
18 an 21 32 43 54 64 75 86 96 107
20 10 20 30 40 50 60 70 80 91 101
22 10 19 29 38 48 57 67 76 86 96 105
24 9 18 27 36 45 54 64 73 82 91 100 109
26 9 17 26 35 43 52 61 69 78 87 95 104

Table 18.—Cumulative percent crown cover for white ash, white pine, red spruce, balsam-fir, and
hemlock, 10 factor prism

D.b.h. Tree count

(inches) 1 2 3 #4 6 6 7 8 9 1 1 12 13 14 «15 #16 17 +18
2 32 64 95 127
4 15 30 «45 60 74 89 104
6 11 21 320 «43-54 6475 86 B07
8 9 18 27 36 44 53 62 71 80 89 98 107
10 8 16 24 32 40 47 65 63 71 79 87 95 103
12 8 15 22 30 38 45 52 60 68 75 82 90 98 105
14 7 14 20 27 34 «41 48 54 61 68 75 82 88 95 102
16 6 13 20 26 32 39 46 52 58 65 72 78 84 91 98 104
18 6 13 19 25 32 38 44 50 57 63 69 76 82 88 94 101 107
20 6 12 18 24 30 37 43 49 55 61 67 «73 79 85 92 98 104 110
22 6 12 18 24 30 35 41 47 53 59 65 71 77 83 88 94 100 106
24 6 12 7 23 «290-35 41 46 52 58 64 70 75 81 87 93 100 104
26 6 W 17 23° 28 34 40 46 #51 57 63 68 74 80 86 OT 97 103



Table 8.—Volumes per acre in cubic feet (4.0-inch ib top) and board
feet (8.0-inch ib top) for unmanaged hardwood stands, by
site index, mean stand diameter, and age

Mean Site 50 __ Site 60 __ Site 70
d.b.h. Cubic Board Cubic Board Cubic Board
(inches) Age feet feet Age feet feet Age feet feet
Years Years Years

4.0 35 30 25

6.0 59 1289 49 1547 41 1821

8.0 83 1606 2983 67 1924 3560 55 2254 4258
10.0 120 1934 5554 87 2311 6640 69 2675 7632
12.0 182 2272 8259 114 2700 9783 85 3144 11461
14.0 157 3102 13048 102 3579 15079
16.0 196 3154 13257 127 3654 15390

50 to 60 tend to be beech-red maple or mixedwood sites;
soil productivity is limited somewhat by shallow, compacted
layers, coarse textures, restricted aeration, or excessive
stoniness. Sites below 50 usually are poorly drained or
shallow to bedrock. Sites below about 50 to 55 are best
suited to growing softwoods, or hardwoods on shorter
rotations (e.g., paper birch and aspen).

Rotation age usually is based on (1) the culmination of
mean annual increment, or (2) the time required to grow a
certain-size tree or product. Tables 8 and 9 indicate that
culmination of mean annual board-foot growth in both
managed and unmanaged stands ranges from about 100 to
120 years. Mean diameters at the point of culmination vary
with site—the range is 14 to 18 inches. Culmination of
mean annual increment for cubic volume occurs at age 40
to 50 in unmanaged stands and 80 to 90 years in managed
stands. In Table 9, some inconsistency is evident in the
trend of mean annual increment because of the timing of
intermediate cuts.

Intermediate Cuttings

Where there are good markets for pole-size material, non-
commercial thinning/cleaning often is not needed; in many
cases, silvicultural needs can be met through commercial
operations in pole stands. However, if an analysis of the
reproduction following clearcutting or shelterwood cutting
indicates that desired species objectives will not be met
(see section on even-age regeneration), a noncommercial
operation may be warranted. The silvicultural objective
should be to increase the proportion of plots dominated by
acceptable species to about 40 percent (equivalent to
C-line stocking). Where the objective is to increase the
proportion of softwood species, cleaning can be done in
seedling stands with selective herbicides. To change the
species mix in hardwood stands, mechanical or chemical

stem treatments should be done in stands between about
10 to 20 years of age. Examples where noncommercial
work might be warranted are in: (1) mixedwood regenera-
tion where the objective is to grow softwoods; (2) mixtures
of valuable hardwoods (yellow birch, sugar maple, ash) in
combination with fast-growing less valuable species such
as red maple; (3) other situations where economic analysis
indicated that costs are justified.

in most hardwood stands between 4 and about 6 inches
mean d.b.h., the stocking guide (Fig. 6) recommends fairly
high stocking for those species that are resistant to natural
pruning. Improvement work during this period might be
accomplished by light, commercially marginal operations
that remove 15 to 25 ft? of basal area per acre. In stands of
paper birch, ash, and aspen averaging 4 to 6 inches d.b.h.,
heavier cuttings down to the B line are permitted for
fuelwood or pulp.

Pruning is not a common silvicultural treatment in northern
hardwoods. But the high value differential between clear
and knotty logs is reason enough to continue to exam the
Prospective costs and returns from this practice. Pruning
probably is most feasible for valuable species that are
moderate to poor self-pruners: sugar maple, yellow birch,
and red oak. Prune trees that are about 4 to 6 inches
during the late summer or dormant season; do not remove
more than a third of the live crown. Do not flush cut. Place
the saw just outside the branch bark ridge and cut down-
ward and slightly outward.

19


Paper, Birch Yellow Birch
120
0 120 } |
=
100
bol _— 100 Leet
(a3.
80 Ac pzaane 20 Lo
LY itd — Lt Q
60 4 = se 60 —t
Lt
ao f+ a wal Th
Lf 0 co
3” *
i 0° 20 30 40 50 60 70 80 90 o” 20 30 40 50 60 70 80 90
bE
x
6 White Ash | Sugar Maple
wi
120 Lal
x hose 120 110.4) ee
too Tos, 100 rn
“| =
; 81.4 S Ther]
80 —s f
ae G 80 = 73.
= 57.9) (60,
60 bio 60 i
oa (46.2)
40 40 oa
pet
20 20.
~~
0 20 30 40 50 60 70 80 90 Oo 20 30 40 50 60 70 80 9
BREAST-HEIGHT AGE (Years)
Figure 8.—Site-index curves (breast height age 50) for paper birch, white ash, yellow
birch, and sugar maple in Vermont and New Hampshire. Values in parentheses are
for site-index breast height age 75 (Curtis and Post 1962b).
Poletimber and Sawtimber Stands (mean d.b.h of overstory 3. Acceptable mature and immature growing
4.0 inches or more) stock 12 inches d.b.h and larger less than:
1. Objective: uneven-age management 25 ft? (hardwoods) or
2. Acceptable mature and immature growing stock 40 ft? (mixedwood)
more than: 4, Total basal area more than:
40 ft2 (hardwood stand) or 100 ft? (hardwood) or
60 ft? (mixed-wood stand) 130 ft? (mixedwood) F
3. Acceptable mature and immature growing 4. Total basal area less than:
stock 12 inches and larger more than: 100 or 130 ft? G
25 ft® (hardwood) or 2. Acceptable mature and immature growing stock
40 ft? (mixedwood) less than: 4
4. Total basal area more than: 40 ft? (hardwood) or
100 ft? (hardwood) or 60 ft? (mixedwood)
130 ft? (mixedwood) D 1. Objective: even-age management
4. Total basal area less than: 2. Stocking of acceptable growing stock less than '
100 or 130 ft? —E C line for the appropriate type

25


Beyond 6 inches mean diameter, commercial thinnings
generally will be feasible, lowering the basal area to about
the B-line level (perhaps in two operations) plus an allow-
ance of 5 to 10 ft? for logging damage. Then, when a stand
reaches one-half to three-fourths of the distance from the B
line to the A line, additional commercial thinnings can be
made to reduce the basal area back to B-line level (plus
damage allowance). Most commercial thinning will be in
the main crown canopy, removing dominant, codominant,
and intermediate trees. Keep in mind that certain types of
marking (from above, from below) may change the residual
mean diameter and also the appropriate B line. The objec-
tive is to provide adequate growing space for the stems
with highest value potential by removing:

1. Risk trees: Valuable trees that will not last until the next
thinning, or that will experience severe degrade.

2. Unacceptable stems: Trees that will not produce sawlog
material now or in the future due to defect or cull.

3. Undesirable species.
4. Acceptable stems crowding high-value stems

Stand Evaluation

Reproduction and Sapling Stands

In these young even-aged stands (mean stand diameter up
to 4.0 inches) the primary need is for a method of judging
the adequacy of stocking and species, and predicting the
need for early noncommercial treatment.

To determine stocking, sample about 2 plots per acre in
each young stand up to a total of about 50; pfot size should
be 8.9 feet (1/700 acre) or 7.4 feet (1/1,000 acre) in diame-
ter. Record:

1, The species that will dominate the plot if left untreated.
This requires the application of all available knowledge on
species growth rates, tolerance, longevity, etc.

2. The desirable species not free to grow (commercial or
desirable species) that will dominate the plot if one or two
undesirable overstory stems are removed.

If at least 40 to 60 percent of the plots are dominated by
desirable free-to-grow stems, the stand should attain C-line
or B-line stocking of acceptable species when it reaches
the lower end of the stocking guide. If stocking of desirable
free-to-grow stems is less than 40 percent, the stocking of

desirable species not free to grow should be examined to
determine whether a precommercial operation will raise the
representation of desirable species to C-line or B-line lev-
els.

Poletimber and Sawtimber Stands

These are even-aged or uneven-aged stands with mean
diameters larger than 4.0 for trees in the main crown can-
opy. Take a minimum of 10 systematically located sample
points in uniform stands, and up to 30 points in variable
stands. On a cumulative tally (Table 10) (or a conventional
tally and with the data in Table 11) record trees counted
with a 10-factor prism by 2-inch diameter classes, and the
following tree classes (denoted by the tally legend):

1. Species or species group (optional)
2. Acceptable growing stock
a. Mature trees (optional if species are tallied)
b. Immature trees (optional)
3. Unacceptable stems
a. Defective (optional)
b. High risk (optional)
c. Cull (optional)

For uneven-age management, the tally should include all
trees in the 6-inch class and larger. For even-age manage-
ment, the tally should include all trees in or touching the
main crown canopy (exclude the suppressed trees). Where
the choice has not yet been made between even-age and
uneven-age management, the tally legend should distin-
guish between suppressed trees and those in the main
crown canopy. Acceptable growing stock will produce
sawlog or better material now or in the future. Unaccept-
able stems will not. Maturity can be tallied in the field using
the size guidelines in Table 5, and current tree condition
can be noted. If the tally legend separates species or spe-
cies groups, maturity can be scored later using the general
guidelines at the bottom of Table 12. Also, in even-age
stands, measure breast height age and total height for up
to five dominant stems per stand to determine site index
(Figs. 8-9). Determine whether the stand is beech-birch-
maple, beech-red maple, or mixedwood. And judge on the
ground whether a commercial cutting is now feasible; this
judgment should be based on volume, quality, accessibility,
and markets.

21


Table 19.—Cumulative percent crown cover for beech, 10-factor
prism

Definitions of Simulated Thinning Regimes 4. 9-inch Thinning: Stands were thinned to B line after
mean stand diameter reached 9 inches and whenever the

1. No Thinning: Stands were allowed to develop naturally. basal area exceeded the B line by 30 ff

2. Quality-line Thinning (Fig. 1): Up to 6 inches mean

stand diameter, stands were thinned once to 80 ft? of basal
area. Above 6 inches mean stand diameter, stands were Pn aoe
thinned OB line ‘whenever the basal area reached 30 f2 respectively. for site indices 70, 60, and 50 feet (site index

for sugar maple at breast-height age 50). Stands were
tl te
ain) he B line (approximately 2/3 the way from B tine to grown to 18.0 inches mean stand diameter. Quality | has

sawtimber potential; quality I! is pulp potential or cull.

Ail runs began at 4.0 inches mean stand diameter, 91 ft? of
basal area per acre, and ages of 25, 30, and 35 years,

3. 7-inch Thinning: Stands were thinned to B line after
mean stand diameter reached 7 inches and whenever the
basal area exceeded the B line by 30 ft?

Table 20.—Residual volumes per acre, by species and quality class (I and I), for no thinning and site
index 60

Residual” White ash
basal
(inches) Age area

Years Ft®

4 30 91 ~ eae

6 49 102 - _ _ _ _ _ _ _ _ = _ - _

8 67 107 49 49 646 441 742 4484 357 285 289 218 2083 1477 3560
10 87 110 98 98 1295 883 1487 969 441 352 580 437 3901 2739 6640
12 114 113 163 163 2167 1478 2488 1622 — > 971 731 5789 3994 9783
14 157-116 = 218 «218 «2890 1970 3318 2164 — — 14295 975 7721 5327 19048
16 196 118 221 «221 «42936 2002 3371 2198 — > 1317 991 7845 5412 13257

18 230 119 224 224 «2972 2026 3412 2225 — — 1332 1003 7940 5478 13418

34


Dense, undesirable understory vegetation will hinder the
establishment of regeneration under the shelterwood sys-
tem. Methods for dealing with this probiem inciude under-
story biomass operations, broadcast chemical treatments,
and the mechanical or chemical treatment of individual
unwanted stems.

The shelterwood system is a good option in mixedwood
stands, especially those with high sawtimber potential. This
system can be used to increase the tolerant softwood
component; to maintain windfirmness if high residual crown
cover is maintained; and to allow for the use of large equip-
ment that tends to destroy understory saplings and poles.

Regeneration

Species favored by clearcutting and dense or open
shelterwood cutting are summarized in Table 2. Clearcut-
tings commonly have 20,000 to 30,000 or more stems per
acre 1 foot tall or taller at 5 years of age. Species composi-
tion is more important than numbers. About two-thirds of
the milacres on clearcut areas generally are dominated
with intolerant or intermediately tolerant species, though
the proportion based on total numbers is less. If advanced
regeneration of tolerants larger than 2 inches d. is
retained, a somewhat lower proportion of
intolerants-intermediates will result. Tolerant softwoods
seldom regenerate well following clearcutting unless well-
established regeneration is present—a type of natural or
unplanned shelterwood.

One approach to evaluating regeneration following clearcut-
ting is to take a series of circular plots, each 1/700 to
1/1,000 acre in size (8.9 to 7.4 feet in diameter). These plot
sizes represent the area occupied by each tree when the
stand reaches 4 to 6 inches d.b.h. (quadratic mean stand
diameter or tree of average basal area) in the northern
hardwood and mixedwood stocking guides (Figs. 6-7).
Determine and record the dominant free-to-grow species—
the species that will dominate the plot using all available
information on tolerance, relative growth rate, longevity,
etc. If the proportion of plots dominated by desirable spe-
cies exceeds 60 percent (many plots contain more than
one commercial stem), this would be equivalent to B-line
stocking or better. Stocking of 40 percent would be about
equivalent to C-line stocking. By also recording the desired
species present that are not free to grow, it is possible to
determine whether the species potential of each plot could
be improved by a weeding operation. For example, a plot
might be dominated by free-to-grow aspen; if removed, the
plot might be dominated by paper birch. in summarizing
the data, it is then possible to examine stocking of accept-
able species both with and without treatment. If the
without-treatment stocking is less than C line, but the with-
treatment stocking is well above the C line, a weeding/
cleaning operation should be considered.

16

Data from shelterwood cuttings in the Lake States indicate
that at least 5,000 well-distributed seedlings per acre, 3 to
4 feet tall, should be present before the removal cut. After
the removal cut, the regeneration can be evaluated using
the plot system described for clearcutting.

In the past, scarification has been recommended for yellow
and paper birches since most studies show much higher
stocking of these birches on scarified seedbeds. However,
scarification operations are expensive and difficult to jus-
tify. Recent experience indicates that summer logging,
which encourages a small amount of scarification from the
logging operation, does not necessarily produce more birch
than winter logging.

Scarification during the seed cut of a shelterwood has been
recommended in the Lake States for regenerating hemlock.
In the Northeast, certain sites—notably the wetter ones—
appear to develop a strong understory of hemlock without
scarification, However, on drier mixedwood sites where
little or no advance regeneration of hemlock is present,
scarification during the shelterwood seed cut would appear
to be helpful.

Planting is seldom done on a commercial scale in northern
hardwoods and related types in the Northeast. However,
where seed sources of desired species are lacking or
genetically improved trees are desired, planting can be
done successfully. We recommend container-grown stock
for rapid growth and minimum mortality. The planting site
needs to be freed of brush or sod—by mechanical or chem-
ical means—to at least 3 to 4 feet around each seedling
location. Posttreatment release often is necessary. In some
areas, it also will be necessary to control damage from
deer, rabbits, and mice. Yellow and paper birches, spruce,
and hemlock all are possible planting candidates.

Stocking

Stocking guides for even-aged hardwood stands are given
in Figure 6 and for mixedwood stands in Figure 7. The
guides apply to the main crown canopy, i.e., excluding the
suppressed trees. Mixedwood stocking applies to stands
with 25 to 65 percent softwoods in the main crown canopy.
The A lines represent the average density of undisturbed
even-aged stands. The B lines represent the minimum
density for maximum basal area or cubic-foot growth. The
charts were developed from both simulated and
remeasured plot data which show that maximum growth
per acre occurs at about 55 to 66 ft? of basal area in hard-
woods. The C line represents minimum stocking—the
minimum amount of acceptable growing stock to make the
stand worth managing. The C line is roughly 10 years’
growth below the B line. Growth per acre (in basal area or
cubic feet) is a little lower at the C line than the B line, and
diameter growth more rapid.


Figure 1.—Cutover stand of northern hardwoods with low to moderate proportion of
sawtimber. Immediate residual goals in such stands would be 30 to 40 ft* of
sawtimber or a q or 1.7 to 1.5. A good northern hardwood site with good-quality sugar
maple, this area could support more sawtimber (lower q) in the future.

Cutting Cycle

The cutting cycle—the years between harvests on the
same area—is determined by accessibility, the need for an
economic harvest, timber growth, and quality. Based on an
average basal growth rate for northern hardwoods of 2
ft?/acre/year a residual stand of 70 ft? will grow to 100 ft?—
a reasonable maximum—in about 15 years. At that time, a
cut of about 30 ft? (8 to 9 cords) will be available. With
good accessibility, high timber values, or high risk of dam-
age from insects or diseases, the cutting cycle might be
iowered to 10 years. Under opposite conditions, cutting
cycles of up to 20 years sometimes are used. With long
cutting cycles, the total residual basal areas in Table 4 can
be lowered to minimums of 60 to 65 ft? for hardwood and
about 75 to 80 ft? for mixedwood, proportioning the reduc-
tions among size classes.

Marking Guides

The success of uneven-age management—both silvicultur-
ally and economically—depends to a large extent on the
choice and application of appropriate marking guides.

Marking guides can be developed from a prism inventory of
the stand, classifying the trees by d.b.h. and condition
classes:

14. Acceptable Growing Stock: Trees with the potential to
produce sawlog or better quality material, now or in the
future, and that are in vigorous condition. These can be
subdivided into mature (based on biological or financial
maturity) and immature. Suggested tree sizes denoting
financial maturity are shown in Table 5.


Table 15.—Estimates of net present value for
northern hardwoods by thinning
regime® and product distribution
(based on projected real stumpage
prices and 4-percent discount rate)

Mean
d.b.h.
(inches)
9-Inch Thinning

8 67 5 12 19 25
10 83 20 33 46 58
12 98 35 54 74 93
14 110 42 66 89 113
16 125 35 58 81 104
18 142 32 55 78 101

7-Inch Thinning

8 64 14 23 32 ay
10 76 36 52 68 85
12 90 50 73 95 118
14 101 66 96 125 155,
16 114 60 89 118 147
18 128 57 86 116 145

Quality-Line Thinning

8 61 20 30 40 50
10 72 48 67 86 105
12 83 66 92 WN7 143
14 95 7 108 139 170
16 107 75 108 140 173
18 119 69 101 133 165

Unmanaged

8 67 5 - - -
10 87 W - - -
12 114 6 _ _- _
14 157 -6 _ - _
16 196 -15 _ _ _
18 230-19 _ _ _

*Thinnings beginning at 9, 7, and approximately 5
(Quality line) inches mean stand diameter, and no thinning
(unmanaged), and with yield schedules as shown in Tables
20-23.

° See Table 13 for product distributions.

Rate of Return

As an alternative to net present value, we might consider a
rate of return analysis of timber management strategies.
The internal rate of return (IRR), for example, is the com-
pound rate of interest that equates the present value of
expected future returns with the present value of expected

future costs. It is the interest rate at which net present
value is zero.

Using the same timber value and cost information that we
used to estimate net present values, we estimated the
internal rates of return for the same management strategies
and product distributions. We found that we might expect
managed northern hardwood stands to yield real rates of
return that range from 5 to 8 percent (Table 16); and that
unmanaged northern hardwoods might, at best, yield rates
below 5 percent.

Note that the IAR cited are real rates. They do not include
the effects of inflation. We can, though, approximate nomi-
nal or market rates by adding our inflation expectations to

Table 16.—Estimates of real rate of return for
northern hardwoods by thinning
regime* and product distribution
(based on real stumpage prices)

Mean

db.h. Stand _

(inches) age

Years ---~----- Porcent- --------

9-Inch Thinning

8 67 5.0 5.3 5.6
10 83 55 5.8 6.1
12 98 57 5.9 62
14 110 57 6.0 62
16 125 5.6 58 6.0
18 142 5.4 5.7 59

7-Inch Thinning
8 64 57 6.2 65
10 76 6.4 7.0 73
12 90 65 7.0 7.3
14 101 6.5 68 7.0
16 114 6.3 68 7.0
18 128 6.2 6.5 67
Quality-line Thinning

8 61 6.2 TA 75
10 72 68 72 75
12 83 69 75 78
14 95 69 74 77
16 107 67 7.0 73
18 119 66 7.0 72

* Thinnings beginning at 9, 7, and approximately 5 (Quality
line) inches mean stand diameter, and with yield sched-
ules as shown in Tables 20-23.

31


The system becomes more complicated when there are
inaccessible or less productive areas on a long cutting
cycle, and productive or accessible areas on a short cutting
cycle. Detailed scheduling is required to assure that
roughly equal yields are harvested each year. A more
formal approach is to divide the inaccessible lands into a
number of cutting units equal to the number of years in the
long cutting cycle, and also to divide the accessible lands
into a number of cutting units equal to the years in the
short cutting cycle. Then, each year, both an inaccessible
and an accessible unit are cut. This approach tends to
regulate both yields and access costs.

With even-age management, there are two components to
the yield: harvest-cutting and thinning yields. in theory, an
even-aged forest is fully regulated when it has roughly
equal acreages in each 10- or 20-year stand age class from
the youngest class up to the class representing the
planned rotation age. As with uneven-age management, it
sometimes is practical to: (1) divide the entire property into
type or accessibility classes, (2) set an appropriate rotation
age and thinning interval for each class, and (3) work
toward an balanced age distribution in each type of acces-
sibility class. To develop a balanced age distribution, har-
vest an acreage per year equal to the total acreage divided
by the planned rotation age. If the entry period for harvest
cutting is more than 1 year, multiply by the number of
years in the entry cycle to determine the acreage to harvest
at each entry.

Thinned acreage commonly is 2 or 3 times the harvest
acreage, though thinned volume may be between 50 and
100 percent of the harvest yields. In an unbalanced even-
aged forest, the thinning yields will be variable because: (1)
the acreage in each age class will be unequal, and (2) the
quality and stocking of some acres in each age class may
not warrant thinning.

Economic Considerations

With moderately intensive silviculture, managed stands can
yield at least 50 percent more volume than unmanaged
stands. Although the increased physical yields seem worth
pursuing, the financial returns from those yields may not
be. The following discussion explores the economic effec-
tiveness of applying silvicultural guidelines in the manage-
ment of northern hardwood forests.

We develop a generalized case to trace the changes in
timber values that we might expect in northern hardwood
Stands over long periods of time under various manage-
ment strategies. We also assign estimates of stumpage
Values and their costs to the volume yields indicated in
Appendix Tables 20-23, and then compare the resulting
timber values. Methods for testing the economic effective-

28

ness of managing a particular stand are available else-
where (Leak 1980).

Hardwood Diversity

in any discussion of northern hardwoods and associated
types, we must first emphasize their diversity. Each species
has its own package of characteristics as to strength, work-
ability, appearance, and appeal. Market prices attest to this
and tend to differentiate relative values among species.

Eastern hardwood stands also are diverse in product poten-
tial. Figure 10 depicts a hierarchy of relative product val-
ues, along with a general woods-run volume distribution
that is typical of many eastern hardwood stands. Although
the actual values vary from one stand to another because
of species and size mix, logging conditions, and markets,
the relative value differences among products often are
large (DeBald 1981).

Timber size and quality are especially important in northern
hardwoods. Figure 11 shows the relative values of trees by
both diameter and butt-log grade. The increased value
through increased size suggests concentrating growth on
selected fast-growing crop trees. The large differences in
tree values from one butt-log grade to another indicate the
importance of concentrating growth on trees that are likely
to impove in grade.

HIGH
VENEER
COOPE RAGE,
HANDLE STOCK
w
2
I
$ SAWLOGS
FIREWOOD
PULPWOOD
Low LARGE

VOLUME

Figure 10.—Typical value/volume hierarchy, eastern
hardwood stands.


Table 2.—Species of regeneration favored (not exclusively) by certain harvesting methods in three

cover types

Individual
tree- Group Dense Open
Type selection selection shelterwood® shelterwood? Clearcut
Beech-birch-maple Sugar mapie Birches Sugar maple Yellow birch Birches
Beech Beech
Beech-red maple Beech Red maple Beech Red maple Birches
Red maple Birches Red maple Yellow birch
Mixedwood Tolerant softwoods Red maple Hemlock Red maple Birches
or hardwoods Birches Spruce Birches

Tolerant hardwoods

*Residual crown cover of about 80 percent.

Residual crown cover of 30 to 50 percent (occasionally up to 70 percent).

However, in assessing each stand, additional factors must
be considered in reaching a decision on the immediate
silvicultural techniques. Either an uneven-age or even-age
approach can be used to grow most species groups or
products: uneven-age management with group selection
can ensure a good mix of intermediate and some intolerant
species; even-age management with shelterwood cutting
can be designed to encourage a high proportion of toler-
ants (Table 2). And rotation age, stocking, stand structure,
and logging equipment can be varied to meet various
product objectives.

One of the important additional factors to consider is cur-
rent stand condition. For example: high-risk stands may
need to be regenerated by clearcutting or shelterwood to
prevent large volume losses; or clearcutting a stand with a
wide range in tree diameter may remove a high proportion
of financially or biologically immature trees.

Another factor is accessibility. With high costs for road
construction, some form of heavy cutting may be the only
economically feasible regeneration harvesting method on
the first entry. Esthetic and wildlife objectives also should
be considered in choosing a silvicultural system. And in
special circumstances, the possibility of site and/or stand
deterioration needs to be assessed. For example, clearcut-
ting on very poorly drained soils without adequate advance
regeneration or in potential frost pockets may result in an
overabundance of herbaceous or shrubby vegetation.

Uneven-Age Management

Harvesting Methods

Uneven-age management is implemented by individual-tree
selection and group selection. Individual-tree selection
removes trees one by one to maintain a fairly uniform and
continuous crown cover appropriate for regenerating toler-
ant species. Group selection is the removal of trees in
groups roughly 1/20 to 2 acres in size. It is especially
appropriate where: (1) the objective is to maintain up to
one-half of the regeneration in intolerant or intermediate
species, and (2) the overstory contains groups of poor-risk,
defective, or overmature trees. Group selection generally is
applied in combination with individual-tree marking
between the groups.

Group selection may be applied in two ways: groups of
overstory trees can be removed, leaving a desirable stand
of seedlings, saplings, or small poles; or entire groups of
trees down to 2-inches d.b.h can be removed. The latter
approach is used to eliminate undesirable sapings and
small poles, resulting in a maximum proportion of intolerant
or intermediate regeneration.

Growth and Yield

Results from a study of residual basal area and structure in
a second-growth, beech-red maple stand illustrate the
typical responses of hardwood stands in New England to
density and structure (Table 3). Basal-area and cubic-foot


Few sitviculturalists can develop expertise in entomology or
pathology. However, they should be able to: (1) recognize
threats to quality and vigor; (2) apply silvicultural and utili-
zation methods that will minimize losses; and (3) know
when to seek expert advice on potential outbreaks. Beyond
this section, few references will be made to specific insects
and diseases. However, many of the silvicultural practices
described later relate to potential stand quality and risk.

Microorganisims that cause decayed and discolored wood,
‘one of the most widespread problems in both hardwoods
and softwoods, enter through dying or damaged roots,
stems, or branch stubs. Other fungi cause collar cracks in
birches and root rot and basal decay in many other spe-
cies. For details on discoloration, decay, and other defects,
see Shigo and Larson (1969) and Shigo (1983).

To limit losses in stand volume and quality from decay and
discoloration, silvicultural methods should be directed
toward (1) removing defective trees during harvest opera-
tions, (2) encouraging the development of small limbs and
early natural pruning by maintaining fairly high stand densi-
ties in sapling and pole stands (or consider artificial prun-
ing), and (3) minimizing logging damage to roots, stems,
and branches. Decay and discoloration associated with
wounds or branch stubs usually do not enter into wood
formed after the wound occurs or after the branch dies.

Nectria cankers are common in many hardwoods, and
Eutypella canker is found on maples. Associated decay is
limited, but wind breakage is common and the cankers
often cause quality defects in the most valuable parts of
the bole.

Beech-bark disease is the most lethal disease of beech.
The beech scale (Cryptococcus fagi (Baer)) punctures the
bark, allowing a bark-killing fungus (Nectria coccinea vac.
faginata) to enter. Small vigorous trees sometimes survive
the disease, though quality may be severely reduced.
Large trees seldom survive. Significant tree-to-tree variation
is evident in susceptibility to both the scale and the Nectria
fungus. Trees exhibiting the characteristic red fruiting
bodies should be harvested without delay.

The saddled prominent (Heterocampa guttivitta) is the most
serious defoliator of beech-birch-maple stands. White ash
and red maple sometimes escape attack, but most other
hardwoods can be heavily defoliated. The outbreaks occur
on about a 10-year cycle, and last 1 to 3 years. Defoliation
in 2 successive years may be followed by widespread
mortality and growth losses, as well as degrade (e.g., stain)
from secondary insects and organisms. Aerial chemical
sprays have proven effective in limiting damage by the
saddled prominent.

Gypsy moth (Lymantria dispar) is the most serious defolia-
tor of oak in central to southern New England. Grey birch,
aspen, and sometimes other hardwoods are frequently
defoliated as well. White pine and hemlock associated with
oak stands also are defoliated during severe attacks. Out-
breaks generally last 1 to 3 years. Mortality and/or growth
loss in oak can be significant after two or more defoliations.
There is some indication that degrade from insects (e.
oak borer) may increase in trees weakened by defoliation.
Insecticidal and biololgical aerial sprays are effective.

Larval galleries of the sugar maple borer (Glycobius
Speciosus) result in partial girdles and cankers that allow
the development of decay and discoloration and increase
susceptibility to wind breakage. Up to 50 to 60 percent of
the sugar maple in a stand may be affected, with an aver-
age of two to three significant cankers per tree. Contrary
to earlier recommendations, exposure of trees by cutting
apparently does not increase susceptibility to damage by
the sugar maple borer

Management Objectives and Approaches

In developing a long-range timber management objective
for an entire forest property, the owner or manager should
first decide on product and species goals. A common prod-
uct objective is high-quality material for veneer logs,
sawlogs, and boltwood combined with utilization of the
poorer quality material for pulp or fuelwood. A second
objective on certain industrial lands or private ownerships
might be maximum production of wood for fiber and/or fuel.
Other product objectives include high-intensity manage-
ment for veneer logs, or production of small logs and
boltwood. The choice of species or species group is closely
related to the desired product, and is concerned with what
species to favor in improving and regenerating the stand.

Two primary factors affecting the choice of product and
species are (1) current and projected markets, and (2) the
capability of the land to grow certain products and species.
Once the product and species objectives are set, a prelimi-
nary decision can be made on appropriate silvicultural
systems for the property. For tolerant species and high-
quality products, one standard approach in the Northeast
has been uneven-age management using individual-tree
selection or some form of partial cutting. For quality prod-
ucts from intolerant and intermediate species, a common
approach is even-age management using clearcutting and
intermediate treatments. Even-age management with
clearcutting is best suited to the mechanized production of
fiber or fuel.


1255 Re

100-4

754

MEAN STAND DIAMETER linches|

50-

BASAL AREA PER ACRE (f

HARDWOOD

T
150

T
450

750 1050

TREES PER ACRE

Figure 6.—Stocking guide for main crown canopy of even-aged hardwood stands
(beech-red maple, beech-birch-maple) shows basal area and number of trees per acre
and quadratic mean stand diameter. The A line is fully stocked, the B line is
suggested residual stocking. The C-line is minimum stocking. The quality line is the
density required to produce high quality stems of beech, sugar maple, yellow birch,

and red maple.

Average density of mixedwood stands is higher than that of
hardwood stands (Figs. 6-7). The mixedwood A line is from
20 to 55 ft? above the hardwood A line. Similarly, the B
line is from 35 to 45 ft? above the hardwood B line when
the percentage of softwood is from 25 to 65 percent of the
basal area of trees in the main crown canopy.

A Quality line also is shown for hardwoods (Fig. 6). Limited
research indicates that species such as beech, sugar
maple, red maple, and yellow birch do not prune well natu-
rally unless grown at 80 ft? of basal area per acre. Paper
birch, aspen, and white ash appear to be the only common
hardwoods in the Northeast that will develop acceptable
quality in small poletimber stands maintained at or near the

B line. At average stand diameters of about 6 inches, clear
lengths of about 1 1/2 logs should be present on many
trees. At this time or after additional clear bole develop-
ment the stand can be thinned back to the B line (plus 5 to
10 ft? to allow for logging damage), perhaps in two opera-
tions if basal area is high and crowns are small. Up to
stand diameters of roughly 6 inches, light improvement
work to maintain species composition and select for stem
quality is acceptable. The Quality line in Figure 6 is dotted
because species compostion and local experience will
influence the level of stocking required in young stands to
ensure quality development. To grow limb-free or small
limbed hemlock and spruce, density should be maintained

17 |


We emphasize that the maximum tree size of 20 inches
d.b.h. is a very flexible goal. Tree vigor and quality are
more important than the specified maximum tree size in
deciding which trees to take or leave. On poor sites, tree
vigor and quality of some species may decline rapidly at 16
inches d.b.h. or larger; on these sites, low amounts of
sawtimber (q = 1.7) are most appropriate. On good sites,
trees may easily be grown to 24 inches or larger; on such
sites, high proportions of sawtimber (q = 1.5 to 1.3)
should be best.

On the basis of these combinations of q and residual basal
area, residual structural goals in terms of basal area per
acre by diameter class are outlined in Table 4 for both
hardwood and mixedwood types. Only three diameter
classes are used since this results in easier application and
allows for some departure from the strict reverse J-shaped
form. Recent information indicates that slightly S-shaped
form of diameter distribution may be more natural, produc-
tive, and economical.

In choosing a structural goal, it often is reasonable to aim
for a q that is about the same as or slightly lower than the
existing q before cutting. The q before cutting can be
judged quickly by using the tabulation for percent
sawtimber. A more precise estimate of the appropriate
residual structure can be developed by following the mark-
ing guide procedures described in the next section. The
structures listed in Table 4 should be used as a guide, and
can be attained by feasible and economical cutting prac-
tices.

The structural goal of q = 1.7 is appropriate for the first
entry in many cutover stands, which often have a low pro-
Portion of sawtimber (Fig. 1). However, the initial cut in a
Previously unmanaged stand may produce an extremely
variable diameter distribution. Total residual density, and
the removal of poor growing stock, are more important than
structure in these early cuts. During subsequent entries, it
may be feasible to leave a higher proportion of sawtimber
(a lower q). On mediocre sites (e.g. beech/red maple
stands), the sawtimber will decline in vigor and growth rate
as it becomes larger, so it may never be possible to grow
large-size trees or to reduce the q below 1.5 or 1.7. On
good sites (e.g., supporting sugar maple/ash) capable of
sustaining high proportions of sawtimber (Fig. 2), q’s of 1.3
are attainable.

On areas scheduled for maximum production of fiber or
fuel, low proportions of sawtimber (a q of 1.7 or higher)
should be best.

In poletimber stands with less than about 25 to 30 ft? of
sawtimber, there is little reason to be concerned about
structure. Such stands can be treated by commercial stand
improvement measures that remove the poorer quality
overstory stems and leave 70 to 80 ft? of basal area per
acre. In subsequent treatments, as the sawtimber compo-
nent develops, the use of structural goats will be more
appropriate.

Table 4.—Minimum stand structure objectives for residual hardwood
(beech-birch-maple and beech-red-maple) and mixedwood

stands
D.b.h. _
class q=1.7 g=1.5 q=1.3
(inches) Hard- Mixed- Hard- Mixed- Hard- Mixed-
wood wood* wood wood* wood wood?

Ft? of basal area/acre-

42 21 30
28 20 28
30 29 42

®Softwood basa! area 25 to 65 percent of total.


Table 11.—Basal area per tree and numbers of trees per acre conversion for a 10-factor prism

Prism Basal area Prism Basal area Prism Basal area
D.b.h. conversion per tree D.b.h. conversion per tree D.b.h. conversion per tree
Inches _ No. trees/acre Fe Inches No. trees/acre Fe Inches No. trees/acre Ft?
1.0 0.0055 11.5 0.7213 22.0 3.8 2.6398
1.5 .0123 12.0 12.7 -7854 22.5 2.7612
2.0 458.4 0218 12.5 8522 23.0 3.5 2.8852
25 0341 13.0 10.8 9218 23.5 3.0121
3.0 203.7 0491 13.5 9940 24.0 3.2 3.1416
35 0668 14.0 9.4 1.0690
4.0 114.6 0873 14.5 1.1467
45 1104 15.0 8.2 1.2272
5.0 73.3 1364 15.5 1.3104
5.5 1650 16.0 7.2 1.3693
6.0 50.9 1963 16.5 1.4849
6.5 -2304 17.0 6.3 1.5763
7.0 37.4 2673 17.5 1.6703
75 -3068 18.0 5.7 1.7671
8.0 28.6 3491 18.5 1.8667
8.5 3941 19.0 5.1 1.9689
9.0 22.6 4418 19.5 2.0739
9.5 4922 20.0 4.6 2.1817
10.0 18.3 5454 20.5 2.2921
10.5 6013 21.0 4.2 2.4053
11.0 15.2 6600 21.5 2.5212

The essential information from the plots can be summa-
rized (Table 12) to provide a basis for either the uneven-
age or even-age stand options. For the uneven-age sum-
mary, the first six basal area columns provide a description
of the initial stand; not all columns need be used, or more
can be added to provide a species breakdown. From these
data, the initial percentage of sawtimber can be deter-
mined, as can the initial approximate q from the tabulation
in the section on uneven-age stocking. If the prescription
key suggests a harvest cutting, the residual goal is deter-
mined by: (1) examining various approaches (marking
rules) for removing the poorer quality material so as to
leave a good-quality stand with the required total basal
area; or (2) using a residual goal based on the initial q of
the stand; or (3) using the general guidelines in Table 6.
The marking goal is simply the difference between the
initial total basal area and the residual goal; however, 5 to
10 ft? may be subtracted from the marking goal for logging
damage.

For the even-age summary, basal area of the initial stand is
listed by tree condition class. Number of trees per acre is
taken from the cumulative tally. Total basal area per acre

and number of trees are used to read mean stand diameter
from the stocking chart (Figs. 6-7). Basal area at the A, B,
C, and Quality lines also are taken from the stocking chart.
If the prescription key calls for a treatment, the residual
goal generally is determined by the B line or Quality line.
However, residual goals higher than the B line may be
prescribed to maintain maximum amounts of quality mate-
rial, for esthetic purposes, etc. The marking goal is the
difference between the initial and residual, minus any
allowance for logging damage. Distributing the residual
goal and marking goal among tree condition classes helps
in the development of marking guides and helps ensure
that the treatment will improve the quality of the stand.

Stand Prescription

Key

Use the following key to identify the stand condition and
find the appropriate prescription (A, B, C, etc.). Details of
the prescriptions follow the key. Also, consult the appropri-
ate section describing the treatment within the text.

23


(B)) Reeser Silvicultural Guide
"potent Sori for Northern Hardwood Types
Northeastern Forest in the Northeast (revised)

Experiment Station

Research Paper NE-603 vate
William B. Leak

fas Dale S. Solomon
Paul S. DeBald



Table 5.—Tree-size objectives (d.b.h.) denoting
peak of possible log-grade improve-
ment (financial maturity) for northern
hardwoods (high and medium-grade po-
tential reflect the marker’s best judge-
ment on tree condition and site poten-
tial for that species)

Grade Log D.b.h.
Species potential? section” objective

Inches

Yellow birch High 1 18

High 2 20

Medium 1 16

Medium 2 18

Sugar and red High 1 18

maple® High 2 20

Medium 1 16

Medium 2 18

Beech High 1 16

High 2 18

Medium 1 14

Medium 2 16

Paper birch High 1 16

High 2 16

Medium 1 12

Medium 2 12

White ash High 1 18

High 2 20

Medium 1 16

Medium 2 18

Red spruce Medium Any 14-16
or better

Hemlock Medium — Any 18-20
or better

*High-grade potential means that the first 1- or 2-log
portion of the stem could produce grade 1 or veneer-
grade logs. Medium-grade potential means that the
highest quality would be no more than grade 2. Grades
are based on USDA Forest Service standard specifica
tions for hardwood factory lumber and veneer logs.

Predominant merchantable height.

In many areas, red maple has medium-quality poten-
tial at best, sod.b.h. objectives commonly are 14 to 16 inches.

10

This hypothetical northern hardwood stand has 57 percent
of the basal area in sawtimber. A stand with a q of 1.5 has
approximately 55 percent of the basal area in sawtimber,
s0 a structural goal of q = 1.5 would be a reasonable first
choice (see tabulation for percent sawtimber). However, in
looking at the tree condition classes, a reasonable set of
marking guides might be:

1. Remove high-risk timber in the 12- to 14-inch class.
2. Remove high-risk timber in the 16+ class.

3. If a cordwood market were available, remove defective
trees in the 6- to 10-inch class

Application of these marking rules would leave a residual
stand as follows:

D.b.h.
class Imma- _ Defec- Goal
(inches) Mature ture tive Total (q=1.7)
------4 ft? of basal area/per acre ~ ~~ - - -
6-10 - 40 - 40 38
12-14 _ 10 10 20 18
16+ 5 5 5 15. _ 14
All 5 55 15 75 70

This residual stand is close to the structural goal of
q = 1.7 in Table 4, and the stand contains a high propor-
tion of vigorous growing stock.

An alternative approach is to follow generalized marking
rules related to stand condition (Table 6). With 65 ft? of
sawtimber, the hypothetical initial stand qualifies as beech-
birch-maple large sawtimber. Total initial basal area is
more than 100 ft, so a cut is warranted using either single-
tree or group selection. The suggested residual basal area
is 75 ft, with 40 to 55 ft? of sawtimber. In this example, the
use of Table 6 leads us into leaving a little more sawtimber
basal area (8 to 23 ft? more), and a corresponding smaller
amount of poletimber, than is suggested by the prism-plot
summary of the actual condition of the growing stock.

Noncommercial Work

Noncommercial stand improvement work is minimal with
uneven-age management because each harvest operation
provides the opportunity to improve the stand by removing
marginal or submarginal trees. However, three types of
noncommercial work are possible.


'
'

a

Tee < Ne © is | —

Figure 2.—Northern hardwood stand with a high proportion of fairly good-quality sugar
maple. The residual goal in this stand would be about 50 ft? of sawtimber or a q of

approximately 1.3,

2. Unacceptable Trees: Trees that will not produce sawlog
or better material now or in the future or trees that are
high risk—subject to mortality or rapid losses of mer-
chantable volume or quality before the next harvest.
Valuable high-risk trees are especially important to
recognize.

3. Cull: Trees with more than 50 percent of their cubic
volume in sound or rotten cull; or use a local or agency
definition.

Certainly, additional tree condition classes could be devel-
oped to meet local timber or wildlife needs. Individual
species or species groups often should be tallied to help
refine silvicultural objectives and develop marking guides.
Prism-plot basal areas, by d.b.h. and tree condition class
can be summarized as in the following example:

D.b.h.

class Imma- Defec- High

(inches) Mature ture tive risk Cull_—_‘Total

----------- ft? basal area/acre- - - -- ------
6-10 _- 40 10 _ - 50

12-14 - 10 10 20 - 40

16+ 5 5 5 10 = 25

All 5 55 25 - 115



Next, we must assign dollar values to potential products
Recent stumpage prices in New Hampshire indicate a wide
range in values by product class and highlight the value
premiums for higher value products (Table 14). They also
point to the importance of encouraging the development of
high-value species.

To evaluate the development of quality over long and vary-
ing timespans, we should include price-change expecta-
tions in our valuations. Let's use real rates of price
change—rates over and above inflation. Using real prices
eliminates the need to make an additional guess at
‘expected long-run inflation rates and reflects the fact that
hardwood lumber-price trends often exceed inflation rates.
Let's use the stumpage prices in Table 14 for a base and
project them to increase in real value as follows:

Log quality Real rate of increase (%)
Veneer and high 3

Medium 2

Low 1

Pallet stock 0s

We can then assign estimates of dollar values to both the
thinnings and the standing volumes shown in Tables
20-23—in real terms. The results will portray the benefits
of quality development and our expectations of how
silvicultural treatments can enhance the development of
quality.

But every benefit has its cost. We need, then, to also con-
sider the costs of maintaining and managing a timber
stand—again, over long and varying timespans. So, let's
assume an annual real cost of $1 per acre for such things
as property taxes and maintaining boundaries. Although
the annuat cost is common to each of the management

Table 14.—Recent typical sawtimber stumpage
prices (adapted from Engalichev 1984)

White Hard Yellow White Red Other

Product class ash maple birch birch oak

-Dollars/M bl- ~~ - ~~ = =

Veneer 115 110 «17045
Sawtimber
High quality 120 90 105 85 135 40
Medium 90 65 80 65 100 30
quality
Low quality 70 50 65 55 75 25
Pallet stock 2 25 «25 55S

strategies, the total costs will vary depending on the
timespans that the management strategies cover. Let's
assume. further, that consulting forester fees account for
10 percent of timber-sale proceeds, a 30-percent income
tax bracket, and capital gains treatment of 40 percent.

Net Present Values

But we also must consider the time value of money. For
most of us, a dollar in hand today is worth more than a
dollar to be received (or spent) 5 years from now. How
much more depends on the rate of return (cost of capital)
that we assume. The values in Table 15, for example, are
net present values, the result of discounting expected net
future values and expected future costs all back to year
zero at a rate of 4 percent, then subtracting the discounted
costs from the discounted values. Discounting to year zero
converts varying timeframes to one common point in time
and allows us to analyze stand-value development over
time. The resulting net present values express all amounts
in equivalent terms—today’s dollars at time zero.

Comparison of different thinning regimes suggest that
silvicultural activities aimed at improving product mix can
result in a substantial increase in value yields (Table 15).
The more we improve the potential product mix, the greater
the value yield.

Although much of the increased value results from
improved product mix, the timing of value yields also is
important. The time required to reach a given mean stand
diameter is considerably shorter with management than it
is without management. Holding costs, then, are lower. But
more important, the discounting period for managed stands
‘of a given mean diameter are much shorter than they are
for unmanaged stands of the same diameter. Note that
‘even if product mix were not improved by thinnings (Table
15, Column A), the net present values of managed stands
are much higher than those for unmanaged stands. The
time value of money is extremely important.

The value of timber removed in thinnings also is important.
The cash flows that they generate add greatly to the overall
value yields from managed stands. In many managed
stands, the net present value of timber sold from thinnings
amounts to almost as much as the net present value of the
standing timber.

The prospect of building up higher timber values faster,
combined with cash flows from thinnings, suggests that
managing northern hardwoods can be worthwhile. Depend-
ing on the degree of improvement in product mix, the value
yields of managed stands can be dramatically higher than
those of unmanaged stands.


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204 ao — —
_ a —_——
_ —_ —_
eo ee
} = v T ——r v T 4
12 14 16 18 20 22 24 26 28 30 32
D.b.h. (Inches)

Figure 11.—Relative values of two-log hard maple trees, by butt-log grade.

Potential Timber Values

The biological recommendatons in this silvicultural guide
capitalize on the diversities mentioned through the manipu-
lation of species mix, tree size, timber quality, and product
objectives. But are higher timber values worth waiting for?
Are they worth working for? The short answer is: probably.
The long answer depends on a number of factors.

One factor concerns the anticipated timber yields them-
selves. As shown earlier, we can expect timber yields
sooner through silvicultural activities. We also can expect
the overall volume yields to be greater. But in order to test
the economic effectiveness of our silvicultural guidelines,
we need to assess the possible dollar returns from those
physical yields, along with their costs.

We must first consider the product potential of a stand with
and without silvicultural treatment (Table 13). We would, for
example, expect a low product potential in unmanaged
stands and higher potentials in managed stands, depend-
ing on our efforts to develop those potentials. In Table 13,
product distribution A represents a typical unmanaged

northern hardwood stand (Filip and Williams 1968). Distri-
butions B, C, and D represent a range of improved product
mixes that might be expected through the application of
silvicultural guidelines, and reflect an upgrading of timber
quality through thinnings.

Table 13.—Assumed percentages of sawtimber

volume
Product Product distribution
A 8 c D
Veneer 2 4 6 &
Sawlogs
High quality 3 6 9 12
Medium quality 40 45 50 55
Low quality 15 15 15 15
Paltet stock 40 30 20 10

29


Table 3.—Net annual growth per acre over a 9-year period of sawtimber (10.5 inches plus) and
total stand (4.5 inches plus), by residual basal area and amount of sawtimber in a
second-growth beech-red-maple stand (approximate site index 55 for sugar maple)

(Solomon 1977)

Residual Residual sawtimber Net growth Accretion
basal area Percent Basal area Sawtimber* Total Sawtimber?
(ft?) Square Board Square Cubic Square Board
feet feet feet feet feet feet
40 30 12 1.4 126 2.2 53 51 46
45 18 1.3 117 2.0 48 68 61
60 24 05 45 18 43 69 62
60 30 18 1.3 17 17 41 55 50
45 27 1.7 153 23 55 76 68
60 36 1.6 144 2.0 48 88 79
80 30 24 2.0 180 1.7 41 64 58
45 36 1.6 144 1.7 4 771 64
60 48 1.0 90 1.2 29 92 83
100 30 30 1.9 i771 17 4 :70 63
45 45 1.6 144 1.2 29 88 79
60 60 141 99 0.9 22 1.07 96

“includes only the sawtimber portion of the stern.

Based on conversions of 90 board feet and 24 ft? per square foot of basal area.

growth generally are best between 40 and 60 ft? of residual
basal area per acre. Board-foot growth, however, is best
between 60 and 80 feet of basal area provided that at least
25 to 36 ft? of basal area in sawtimber is maintained. With
these fairly low sawtimber basal areas, much of the
sawtimber growth is ingrowth into the larger sizes rather
than accretion. Accretion tends to rise as the basal area in
sawtimber approaches 50 to 60 ft?; however, mortality and
lower sawtimber ingrowth reduce the net sawtimber growth.
Retention of live branches is noticeable at 60 ft® basal
area, indicating that timber quality development should be
best at residual basal areas of 70 to 80 ft”.

On better sites, those supporting beech-birch-maple
stands, experience indicates that higher amounts of resid-
ual sawtimber could be maintained that produce high-
quality sawtimber growth.

Stocking and Structure

Recommended minimum residual basal areas in trees 5.0
inches and larger in d.b.h. are:

Type Residual Basal Area (f2)
Beech-birch-maple 70 (65-75)
Beech-red maple 70 (65-75)

Mixedwood 100 (80-120)

The mixedwood goal applies to residual stands with 25 to
65 percent softwood in trees 5.0 inches and larger in diam-
eter. A range in basal area is given to encourage flexibility.
On good sites, those with an abundance of quality timber,
residual basal areas above the suggested range may be
specified. However, residual basal areas below the sug-
gested range may impair quality development.

Stand structural goals for uneven-age management are
specified by the maximum size tree to leave, and the diam-
eter distribution, Diameter distributions are approximated
by a reverse J-shaped curve, with a slope defined by q—
the quotient between numbers of trees in successively
smaller d.b.h. classes.

The structural goals in this guide are based on a range in q
from 1.3 to 1.7, and a maximum tree size (for general
planning purposes) of 20 inches d.b.h.:

q_ Approximate percent sawtimber

17 45
1.5 55
1.3 70


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Leak, William B.; Solomon, Daie S.; DeBald, Paul S. 1987. Silvicultural
guide for northern hardwood types in the Northeast (revised). Res.
Pap. NE-603. Broomall, PA: U.S. Department of Agriculture, Forest
Service, Northeastern Forest Experiment Station. 36 p.

A practical guide to the management of northern hardwoods for timber
Production in New England and New York. Both even-age and uneven-age
management are considered, and specific treatments are prescribed for a
range of stand conditions and management objectives.

ODE 614:22:176.1(74)

Keywords: northern hardwood; silvicultural guide: management guide;
stocking



Headquarters of the Northeastem Forest Experiment Station are in Broomall, Pa.
Field laboratories are maintained at:
© Amherst, Massachusetts, in cooperation with the University of Massachusetts.
© Berea, Kentucky, in cooperation with Berea College.
@ Burlington, Vermont, in cooperation with the University of Vermont.
© Delaware, Ohio.
© Durham, New Hampshire, in cooperation with the University of New Hampshire.
Hamden, Connecticut, in cooperation with Yale University.
@ Morgantown, West Virginia, in cooperation with West Virginia University,
Morgantown.
@ Orono, Maine, in cooperation with the University of Maine, Orono.
© Parsons, West Virginia.
@ Princeton, West Virginia.

Syracuse, New York, in cooperation with the State University of New York
Coliege of Environmental Sciences and Forestry at Syracuse University,
Syracuse.

@ University Park, Pennsylvania, in cooperation with the Pennsylvania State
University.
@ Warren, Pennsylvania.

Persons of any race, color, national origin, sex, age, religion, or with any handicap-
ping condition are welcome to use and enjoy ail facilities, programs, and services
of the USDA. Discrimination in any form is strictly against agency policy, and
should be reported to the Secretary of Agriculture, Washington, DC 20250.


COMPARATIVE SITE INDEX BASE AGE 50
10
~ yWA
100
8 90 A ia
© VAVOAA
5 80 7 Py
a Zr
+ V
© 70 Y
Py 4
& 60
x
3 50
z
E 40
a
30

Figure 9.—Relationships among site indices (base age 50)
for white ash, paper birch, yellow birch, and sugar maple,
To estimate site index of species X from site index of
species Y: find known site index on curve for species Y;
move vertically up or down to curve until species X is
located; read horizontally across to the left to find esti-
mated site index for species X (Curtis and Post 1962a).

2. Stocking of acceptable growing stock more than
Cline
3. Stand mature”

4. Objective: intolerant and intermediate J
species
4. Objective: tolerant species K

3. Stand not mature
4. Stand more than 6 inches mean stand
diameter and adequate clear length
developed
5. Total stocking more than halfway
between A and B lines

‘Mature: (1) at rotation age, (2) at mature size, based on
product objectives, or (3) 50 percent or more of the basal
area in mature trees.

26

6. Commercial thinning feasible now or

within 10 years L
6. Commercial thinning not feasible now
or within 10 years M
5. Total stocking less than halfway
between A and B lines N

4. Stand less than 6 inches mean stand
diameter, or clear length not weil
developed
5. Total stocking more than Quality line

6. Light commercial thinning feasible
now or within 10 years 0
6. Light commercial thinning not feasi-
ble now or within 10 years
5. Total stocking less than Quality line

ov

Prescriptions

A. This young stand should develop naturally into an ade-
quate pole stand with at least C-line stocking of desir-
able species. Noncommercial treatment is not required.

B. This young stand will develop into a pole stand with C
line stocking of desirable species only if cleaned
precommercially. Benefits and costs of such treatment
should be examined using all available information on
site, species response, and managment objectives.
Apply the treatment if warranted.

C. Even if cleaned precommercially, this young stand will
not develop C-line stocking of desirable species. Reex-
amine the stand in 10 to 20 years to determine the best
treatment options—including the possibility of biomass
harvesting for fuel or fiber.

D. This stand has suitable quality, structure, and basal
area to implement uneven-age management. Develop
and apply marking guides to meet goals for residual
basal-area structure, tree condition, and regeneration.
Consider both single-tree and group selection.

E. This stand has suitable quality and structure to imple-
ment uneven-age management. But stand density is not
critically high. Reexamine in 10 to 20 years, unless the
possible loss of valuable high-risk trees warrants imme-
diate harvest cut by selection or group-selection meth-
ods.

F. This stand has suitable quality and density to initiate
uneven-age management, but sawtimber stocking is
low. Apply a commercial improvement cut, removing
lower quality overstory stems, leaving a residual basal
area of about 65 to 70 ft? (hardwood) or 80 to 100 ft?
(mixed wood) per acre plus any allowance for logging
damage.


Mixedwood (hardwoods with primarily spruce, hemlock, or
balsam-fir) stands have at least three origins: (1) partial or
heavy cutting of softwood stands, which allowed hardwood
invasion to occur; these stands appear as the beech-red
maple cover type with a softwood component or under-
story; (2) forest succession on abandoned fields, which
tends to favor increased proportions of white pine, hem-
lock, spruce (red or white), or balsam-fir even on good
hardwood sites that normally would support the beech-
birch-maple type; and (3) diverse site conditions, e.g.,
shallow or rocky soils interspersed with better soils, which
results in groups of hardwoods and softwoods. Because of
different origins, successional trends in mixedwood stands
may be toward tolerant softwoods, hardwoods, or mainte-
nance of the mixedwood character.

Type Distinguishing Factors
Beech-birch-maple 1. Fifteen percent or more sugar
maple in overstory and/or
understory.
2. Sugar maple more abundant than
red maple.
Less than 25 percent softwoods in
overstory or understory.

4. Commonly found on well- to
moderately well-drained
fine-textured till soils.

Beech-red maple 1. Less than 15 percent sugar maple
in overstory and understory.

Red maple more abundant than
sugar maple.

Less than 25 percent softwoods in
overstory and understory.

4. Commonly found on soils that are
wetter, drier, more shallow to
bedrock or pan, rockier, or more
Poorly aerated than those
supporting beech-birch-maple
stands.

Mixedwood 1. Softwoods (primarily spruce,
hemlock, or balsam-fir) account for
25 to about 65 percent of the
overstory and/or understory.

2. No specifications on the relative
Proportions of sugar maple and red
maple.

3. Found on a wide variety of soils
due to the varied past history and
origin of mixed-wood stands.

»

N

cay

Note that certain intolerant or intermediate species—paper

birch, yellow birch, aspen, etc.—are not indicative of site
condition.

Silvicultural opportunities differ for each subtype. The
beech-birch-maple type regenerates and produces large,
high-quality hardwoods such as sugar maple, yellow birch,
or, in some areas, white ash. The beech-red maple type
commonly produces smaller, lower grade sawlogs. How-
ever, such areas can produce acceptable boltwood stems
(birches) or aspen for wildlife; oak sawlogs are a possibility
in certain parts of the northern hardwood region. In many
mixedwood stands, the possibilities for hardwood products
are similar to those for the beech-red maple subtype. Here,
volume production can be increased by gradually favoring
the softwood component. However, due to the variable
origin of mixedwood stands, large high-quality hardwoods
can be grown on some sites.

Silvical characteristics of the important species found in
these three types are outlined in Table 1. The
shade-tolerance categories of tolerant, intermediate, and
intolerant indicate whether the species can regenerate and
persist under conditions of heavy, moderate, or no shade,
respectively. Moderate shade would be about 30 to 70
percent crown cover.

The categories of early height growth indicate the general
ability of a species to outgrow its associates up through the
sapling stage with no overhead competition. For example,
aspen grows very fast and seldom needs release from
associated species to maintain a dominant position, and
red maple normally is outgrown by aspen and paper birch.
Sugar maple and beech are outgrown by most other hard-
wood species even when free of competition.

The relative site requirements vary by species. White ash,
and sugar maple to a slightly lesser extent, are most abun-
dant and reach best development on the best soils. Con-
versely, spruce, hemlock, and white pine are common and
grow to fairly large size on soils that are shallow, rocky,
sandy, or wet. Paper birch, red maple and aspen, though
fast growers on good sites, can be reproduced and grown
fairly successfully on poor sites.

The natural pruning categories refer to a species’ relative
ability to produce clear boles. The softwoods, as well as
sugar maple and beech, only produce clear boles at an
early age under conditions of high stand density. However,
paper birch, white ash, and aspen produce clear straight
boles at only 50 to 60 percent of maximum stand density.

Protection

Diseases and insects are the two important problems. Fire
damage and prevention have a minor impact on
silvicultural methods in northern hardwoods and related

types.


Figure 3.—Portion of a group-selection opening in nearly mature northern hardwoods.
Complete removal of the understory will result in maximum amounts of intolerant-
intermediate regeneration.

managed stands, the percentage of milacres stocked with
at least one stem between 3 feet tall and 1.5 inches d.b.h.
usually exceeds 65 percent. Percent stocking of desirable
species much lower than this—below 50 percent, for exam-
ple—would indicate the need for special attention to regen-
eration, pethaps the use of small group-selection openings.
The number of stems of commercial species (1.5 to 4.5
inches, or in the 2, 3, and 4-inch classes) commonly ranges
from about 200 to 450. If adequate stocking in the seedling
class is present, but 2- to 4-inch saplings seem deficient, a
harvest cutting to the recommended residual basal area
should solve the problem. There is no concensus at
present on the need for mechanical or chemical treatments
to improve the composition of the seedling-sapling compo-
nent under single-tree selection. Work on the Bartlett
Experimental Forest with single-stem timber stand improve-
ment in understory beech produced little permanent
change at high cost. However, the subject deserves further
study.

Even-Age Management

Harvesting Methods

Two even-age harvest cutting methods commonly used in
the Northeast are clearcutting and shelterwood. The seed-
tree method also is recommended sometimes for large
cutting areas where the available seed source of desired
species is limited.

Clearcutting is the harvesting of all merchantable trees on
an area generally followed by a chemical or mechanical
removal of trees down to 2 inches d.b.h. (Fig. 4). Some-
times groups of trees larger than 2 inches d.b.h. are left if
they are of desirable species. Isolated residual trees may
develop large limbs and poor quality. However, pole-size or
larger sugar maple with good crowns, clear boles, and no
tendency to produce epicormic sprouts will experience little

13


for hardwoods (60 to 70 ft) and softwoods (100 to 120 ft2);
for intermediately tolerant regeneration (chiefly yellow
birch), the seed cut should leave a residual stand of about
30 to 50 percent crown cover (30 to 40 ft?); perhaps a little
higher on wet sites. Marking for seed cuts (and preparatory
cuts) must be from below, removing smaller stems as first
priority, and leaving a uniformly distributed stand. Tables
17-19 in the Appendix help relate crown cover to basal
area by species group. These tables allow shelterwood
prescriptions to be written in terms of crown cover or basal
area, or both.

The final removal cut for any species should be made
when the regeneration is 3 to 4 feet tall or more for most
species (> 2 feet for birch; > 1 foot for spruce). Winter
removal minimizes logging damage to the regeneration.
However, summer removal is a possibility with hardwoods

Ae Pe

wi .
Figure 5.—Shelterwood seed cut in northern hardwoods leaving approximately 70
percent crown cover (approximately 60 ft? of basal area per acre). Marking from below
followed by brush saw removal of stems under 5.0 inches d.b.h. has created ideal
conditions for regenerating tolerant and moderately tolerant species.

because of their sprouting ability. Other logging precau-
tions to minimize damage to the regeneration include the
careful layout of major skid trails, directional felling, log-
length skidding, and the use of winching devices.

In previously cutover stands, where a good stocking of
saplings and poles are present under an existing overstory,
a natural shelterwood can be applied simply by removing
the overstory. The main concerns are damage to, and
adequate stocking in, the residual stand. Several planned
modifications to the shelterwood system have been tried
where the time between the seed cut and removal cut has
been lengthened to maintain continual cover for esthetic
purposes; these are known as delayed or extended
shelterwoods, in the extreme, this approach becomes a
two-age system where removal cuts are made at half-
rotation intervals.

15


Purpose and Scope

This is the third silvicultural guide for northern hardwoods
(beech-birch-maple) in the Northeast. The first, published in
1958 (Gilbert and Jensen 1958), provided general guide-
lines on initial cutting methods in uneven-aged old-growth
stands and even-aged second-growth stands. The second,
Published in 1969 (Leak et al. 1969), provided quantitative
information on stocking and yield as well as a key to spe-
cific stand presecriptions, particularly for even-age manage-
ment. This revised guide inctudes new information on
forest types, site, stocking, growth and yield, and regenera-
tion methods, including shelterwood and group selection.

The information in this guide applies to about 20 million
acres of northern hardwood and mixed hardwood-conifer
types across New England and New York. Outside this
area, the guide should be applied with caution. The guide
is primarily concerned with timber production. A guide to
the management of wildlife habitat in hardwood and conifer
types in New England is in preparation.

Regional Conditions

Northern hardwoods and associated species are used for a
variety of products, including veneer, sawlogs, boitwood,
pulpwood, fuelwood, and miscellaneous products such as
posts. In New England, sawlogs and veneer presently
account for about one-quarter of the hardwood harvest, and
pulpwood accounts for about one-half. In states such as
New Hampshire, fuelwood currently accounts for a signifi-
cant proportion of the hardwood cut. In many areas, mar-
kets for low-quality material provide opportunities for
improving the northern hardwood forest without heavy
investments in noncommercial silvicultural work. Also,
substantial increases in land and timber prices over the last
10 to 15 years have strengthened timberland investments.
Indications are that current trends will continue upward,
though perhaps at a lower rate.

Many timberland owners in New England own land prima-
rily for reasons other than growing timber. In New Hamp-
shire and Vermont, only 6 percent of the owners,
controlling 21 percent of the timberland, listed wood pro-
duction as one of the important reasons for ownership
(Kingsley and Birch 1977). Foresters must consider the
other values of timberland—recreation, esthetics, buffers,
wildlife, investment, etc.—and be prepared to use
silvicultural approaches that will complement or enhance
these values.

Species and Sites

Three cover types, or subtypes, are described in this
guide: beech-birch-mapte (typical northern hardwood),
beech-red maple, and mixedwood (hardwoods and associ-
ated softwoods). The occurrence of these types usually is
related to site conditions—soils, climate, and bedrock
Mineralogy; in parts of the Northeast, these forest types are
known to occur on certain land types, forest habitats, or
Soil series. Those who manage stands primarily for paper
birch, oak, white pine, spruce-fir, or cherry-maple should
use the guides written specifically for those types.

The beech-birch-maple type contains sugar maple as the
characteristic species in proportions ranging from 15 to 20
percent to nearly 100 percent of the basal area. This type
is characteristic of well- to moderately well-drained, fine-
textured or loamy till soils. Sugar maple and/or white ash
are most abundant on the best soils—for example, those
that are enriched with organic matter or derived from lime-
stone. However, on average beech-birch-maple sites,
beech may account for up to 50 percent of the basal area.
The most common birch species are yellow and paper
birches. However, in southern New England, sweet birch
and northern red oak (often of good quality) may be com-
mon associated species. The successional tendency is
toward the tolerant species—beech and sugar maple.

Beech-red maple stands usually occupy poorer sites than
beech-birch-maple stands—soils that are more shallow,
wetter, or drier than those with typical northern hardwoods.
The central characteristic of these hardwood stands is that
sugar maple is uncommon and/or slow growing. On dry
sites, beech may be the predominant species. On wet sites
or shallow soils, red maple often is the most common
species. Yellow birch and paper birch (or sweet birch in
southern New England) are common associates. Some of
these stands originated from heavy cutting of softwood or
mixedwood stands. Old stands sometimes show a succes-
sional trend toward tolerant softwood types—hemlock
and/or red spruce. Or the successional tendency may be
toward a predominance of beech. Some of the characteris-
tic soils are productive for red oak; less so for sugar maple,
yellow birch, or white ash.


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Table 12.—Summary table for uneven-aged or even-aged stand
diagnosis (example from Table 10)

Possible
D.b.h. residual Possible
class High goals marking
(inches) Maturetmmature Defective risk Cull Total (Q=1.5-1.7) goals
-Fl------------------
UNEVEN-AGED.
6-10 40 10 50 30 38 20 12
12-14 10 30 40 20 18 20 22
16+ 5 5 15 25 20 14 511
All 5 55 55 115 70 70 45 45
Initial % Sawtimber = 57 Initial Q = 1.5
EVEN-AGED
Tree Initial Residual Marking
condition stand goal goal
Mature 5 5 0
immature 45 45 0
Defective- 55 14 4
high risk _ __
All 105 64 41
No. Trees 149 Commercial Cutting Mature D.b.h. (inches)
MSD 11.4 — Feasible 20 - SM, YB, WP, Hem
A line BA 112 — Not feasible 18 ~ Be, WA, RO
B line BA 64 16 - RS, RM
C line BA 48 12 — PB, Asp., BF
Quality line BA —

Bole Condition:

___ Clear merchantable length
_— More natural pruning needed

Site-Index Trees

Species BL
Age 70
Height 70
Site 60 _ __

Reproduction or Sapling Stands (Mean d.b.h. of Overstory
Less Than 4.0 Inches)

1. 40 percent or more of the plots stocked with a desirable
free to grow stem (untreated). A

1. Less than 40 percent of the plots stocked with a desir-
able free to grow stem (untreated).

24

2.

More than 40 percent, preferably more than 60
percent, of the plots stocked with a desirable stem
not free to grow. B

. Less than 40 percent of the plots stocked with a

desirable stem not free to grow. c


Abstract

A revision of the 1969 silvicultural guide for northern hardwoods, provides up-to-
date information on both even-age and uneven-age silviculture and management
for beech-birch-maple, beech-red maple, and mixedwood stands in the North-
east.

The Authors
WILLIAM B. LEAK is principal silviculturist with the Northeastern Forest Experi-
ment Station at Durham, New Hampshire. DALE S. SOLOMON is principal

mensurationist with the Northeastern Station at Orono, Maine. PAUL S. DEBALD
is a research forester with the Northeastern Station at Delaware, OH.

Manuscript received for publication 24 September 1986.

Northeastern Forest Experiment Station
370 Reed Road, Broomall, PA 19008
August 1987

COVER—Many-aged northern hardwood stand after improvement cutting, Bartlett
Experimenta! Forest


the real rates.? For example, if we expected a 7 percent
rate of return over over a span of years, along with an
average inflation rate of 4 percent, the nominal IRR would
be approximately 11 percent. The tough (if not impossible)
Part of making the conversion is trying to predict future
inflation rates.

The differences in possible value yields, with and without
management, seem wide enough to demonstrate the eco-
nomic effectiveness of adopting silvicultural guidelines in
the management of northern hardwood forests generally,
and to warrant taking a closer look at the management
potentials of individual stands, specifically.

Literature Cited

Curtis, Robert O.; Post, Boyd W. 1962a. Comparative site
indices for northern hardwoods in the Green Moun-
tains of Vermont. Stn. Pap. NE-171. Upper Darby, PA:
U.S. Department of Agriculture, Forest Service, North-
eastern Forest Experiment Station. 6 p.

Curtis, Robert O.; Post, Boyd W. 1962b. Site index curves
for even-aged northern hardwoods in the Green
Mountains of Vermont. Bull. 629. Burtington, VT: Uni-
versity of Vermont Agricultural Experiment Station. 11 p.

DeBald, Paul S. 1981. Estimating timber stand values: A
guide to treatment. In: Proceedings of the national
silviculture workshop; Roanoke, VA; June 1-5, 1981;
Washington, DC: U.S. Department of Agriculture, Forest
Service. p. 237-247.

Engalichev, Nicolas. 1984. New Hampshire forest market
report, 1983. Ext. Publ. 11. Durham, NH: University of
New Hampshire, Cooperative Extension Service. 34 p.

Filip, Stanley M.; Williams, Frank W. 1968 Volume and
value of products harvested from a northern hard-
wood clear cutting. Northern Logger. 17(4): 22-23.

?Actually, we would use the formula (1+n)=(14+"(1+i)
when n, r, and i are the decimal equivalents of the
nominal (or market), real, and inflation rates, respectively.
Conversions between real and nominal rates should be
made by multiplying and dividing, not by adding and
subtracting.

32

Gilbert, Adrian M.; Jensen, Victor S. 1958. A management
guide for northern hardwoods in New England. Stn.
Pap. NE~112. Upper Darby, PA: U.S. Department of
Agriculture, Forest Service, Northeastern Forest Experi-
ment Station. 22 p.

Kingsley, Neal P.; Birch, Thomas W. 1977. The forest-land
owners of New Hampshire and Vermont. Resour. Bull.
NE-51. Upper Darby, PA: U.S. Department of Agricul-
ture, Forest Service, Northeastern Forest Experiment
Station. 47 p.

Leak, William B. 1980. Rapid economic analysis of north-
ern hardwood stand improvement options. Res. Note
NE-296. Broomall, PA: U.S. Department of Agriculture,
Forest Service, Northeastern Forest Experiment Station.
6p.

Leak, William B.; Solomon, Dale S.; Filip, Stanley M. 1969.
A silvicultural guide for northern hardwoods in the
Northeast. Res. Pap. NE-143. Upper Darby, PA: U.S.
Department of Agriculture, Forest Service, Northeastern
Experiment Station. 34 p.

Shigo, Alex L. 1983. Tree defects: a photo guide. Tech.
Rep. NE-82. Broomall, PA: U.S. Department of Agricul-
ture, Forest Service, Northeastern Experiment Station.
167 p.

Shigo, Alex L.; Larson, Edwin H. 1969. A photo guide to
the patterns of discoloration and decay in living
northern hardwood trees. Res. Pap. NE-127. Upper
Darby, PA: U.S. Department of Agriculture, Forest Ser-
vice, Northeastern Forest Experiment Station. 100 p.

Solomon, Dale S. 1977. The influence of stand density
and structure on growth of northern hardwoods in
New England. Res. Pap. NE-143. Upper Darby, PA:
U.S, Department of Agriculture, Forest Service, North-
eastern Experiment Station, 34 p.

Solomon, Dale S.; Leak, William B. 1985. Simulated yields
for managed northern hardwood stands in New
England. Res. Pap. NE-578. Broomall, PA: U.S. Depart-
ment of Agriculture, Forest Service, Northeastern Forest
Experiment Station. 24 p.


G. This stand has suitable quality for uneven-age manage-
ment, but sawtimber stocking is low and stand density
is not critically high. Reexamaine in 10 to 20 years

H. This stand has too little quality growing stock for effi-
cient uneven-age management. Reconsider the possibil-
ity of even-age management through clearcutting or
shelterwood cutting. The other alternative is a long
series of improvement cuts and selection/group selec-
tion to gradually improve the condition of the stand.

|. Acceptable growing stock is inadequate. Plan to regener-
ate the stand with Clearcutting, strip cutting, or
shelterwood cutting when commercially feasible.

e

Apply clearcutting to maximize the proportion of intoler-
ant and intermediate species. Strip cutting should maxi-
mize intermediates such as yellow birch. In sensitive
areas, a heavy two-cut shelterwood can be applied by
leaving 30 to 50 percent residual crown cover (30 to 40
ft?) following the seed cutting and removing the overstory
in about 5 years.

K. Use a light two-cut shelterwood, leaving about 80 per-
cent or more crown cover (60 to 70 ft? of basal area),
during the initial seed cutting and removing the
overstory when the tolerant advanced regeneration is
more than 3 feet tall.

L. This immature stand has adequate young growing stock
for even-age management, and sufficient stand density
to support a commercial thinning. Stands should be
thinned to not below the B line. However, only up to one
third of the main canopy basal area should be removed
at any one time. In stands within about 20 years of
maturity, commercially thin only if there will be losses in
volume or value if the stand is left untreated until final
harvest.

M. This immature stand has adequate acceptable growing
stock and density for even-age management, but com-
mercial thinning is judged not feasible because of
accessibility, current markets, etc. Leave untreated until
commercial thinning prospects improve.

N. This immature stand has adequate acceptable growing
stock for even-age management, but stand density is
not critically high. Reexamine in 10 to 20 years.

O. This immature stand has sufficient potential quality and
density for even-age management, but adequate clear
length has not yet developed. Light thinning or improve-
ment cutting to the Quality line, removing a small
amount of poor quality or risky material, is permitted;
this option is best suited to stands where quality, spe-
cies, and site index are above average.

P. This immature stand has sufficient quality and density
for even-age management, but adequate clear length
has not yet developed. Light thinning is judged not
feasible. Leave untreated, and reexamine in 10 years.

Q. This immature stand has sufficient potential quality for
even-age management, but adequate clear merchant-
able length has not yet developed. For production of
quality material, leave the stand untreated so that
increasing stand density will encourage natural pruning.
For fuelwood production, the stand may be thinned to B
line.

Regulation

Regulation refers to the methods used to control the
amount and periodicity of timber yields from a property.
Commercial timberland owners, industrial owners, and
certain large public ownerships may need regular, sus-
tained or increasing yields. Owners of small tracts may
have less need to control yields.

With uneven-age management, periodic yields from each
‘stand or group of stands are achieved by setting a residual
stand density, structure, and growing-stock condition (in
terms of risk and quality potential) that will produce good
volume or value growth over the cutting cycle (see Tables 3
and 4).

The first cut in a heavily stocked stand will produce fairly
high gross yields, but may be low in net yield and value.
Ensuring harvests in any stand are made at intervals equal
in length to the cutting cycle. During these harvests, resid-
ual stand density is roughly consistent, though the propor-
tion and quality of the residual sawtimber may be increased
gradually until it reaches a desirable level. This approach
will result (after the first cut) in fairly constant cubic-foot
yields roughly equal to annual growth times the cutting
cycle, and gradually increasing sawtimber yields until an
essentially constant level is reached.

On a large uneven-aged property, where annual yields are
feasible and desired, the entire property can be divided into
a number of cutting units or groups of stands equal to the
years in the cutting cycle. Then, each year, a different
cutting unit is harvested to provide an annual yield. At the
outset, units are entered in order of priority based on matu-
rity, risk, stocking, etc.

Uneven-age regulation commonly is called volume, basal
area, or growing-stock control. However, since the cutting
units will have roughly equal acreages (or acreages
inversely proportional to productivity), there is some ele-
ment of area control involved as well.


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Figure 4.—Clearcutting in northern hardwoods with essentially complete removal of
the understory.

degrade when left as residuals to increase the tolerant
component of the new stand. Clearcutting boundaries can
be designed to follow natural stand or topographic bound-
aries to minimize adverse esthetic impacts.

Progressive stripcutting is a variation of clearcutting that is
especially well suited to the regeneration of yellow birch
and other intermediate species. Strips 50 to 100 feet wide
are laid out along the contour. In the first cutting, every
third strip is removed; 2 to 4 years later, one strip next to
each initially cut strip is removed. After another 2- to
4-year interval, the final strips are cut. Trees down to 2
inches d.b.h. are removed or felled. The material generally
is skidded down the strips currently being cut, which
results in a high degree of scarification and the removal of
most undergrowth.

14

In mixedwood stands on wet areas, where windthrow would
be a threat under unevenage or shelterwood systems,
narrow strips (30 to 50 feet wide) sometimes are used to
help perpetuate a softwood component. Winter logging
usually is advisable in these areas, and softwood regenera-
tion is most probable if the strips contain established
softwood seedlings.

In the Northeast, the shelterwood system commonly is
applied in two cuts: an initial seed cut (Fig. 5) and a final
removal cut. Where the objective is to regenerate tolerant
species and little or no advanced regeneration is present,
an initial light preparatory cut also may be desirable to
stimulate seed production of desirable species and the
establishment of small seedlings. For tolerant regeneration,
the seed cut should retain about 80 percent crown cover