Partial cutting practices in old-growth lodgepole pine : a field guide

Historic, Archive Document

Do not assume content reflects current
scientific knowledge, policies, or practices.

f f^jfSL 'U it Service
0#p>3 per RM-92A

Rocky Mountain Forest and
Range Experiment Station

Forest Service

U. S. Department of Agriculture
Fort Collins, Colorado

PARTIAL CUTTING
PRACTICES IN "
OLD-GROWTH
LODGEPOLE PINE

A Field Guide

by Robert R. Alexander

02^06

INTRODUCTION

This field guide was prepared to aid the for-
est manager in identifying different stand
conditions and developing partial cutting
practices needed to maintain permanent forest
cover. Detailed information on tree and
stand characteristics, windfall risk, insect
and disease susceptibility, and cutting
practices to integrate timber production
with other uses is given in USDA Forest
Service Research Paper RM-92, "Partial
Cutting Practices in Old-Growth Lodgepole
Pine."

WINDFALL RISK SITUATION

A. LOW RISK

1. Valley bottoms except where parallel to the pre-
vailing winds, and all flat areas.

2. All lower and gentle middle north- and east-
facing slopes.

3. All lower and gentle middle south- and west-
facing slopes that are protected by considerably
higher ground not far to windward.

B. MODERATE RISK

1. Valley bottoms parallel to the direction of
prevailing winds.

2. All lower and gentle middle south- and west-
facing slopes not protected to the windward.

3. Moderate to steep middle and all upper north-
and east-facing slopes.

4. Moderate to steep middle south- and west-facing
slopes protected by considerably higher ground
not far to windward.

C. HIGH RISK

1. Ridgetops.

2. Moderate to steep middle south- and west-facing
slopes not protected to the windward and all
upper south- and west-facing slopes.

3. Saddles in ridgetops.

The risk of windfall in these situations is increased at
least one category by such factors as poor drainage,
shallow soils, and defective roots and boles . All situa-
tions become high risk if exposed to special topographic
situations such as gaps and saddles in ridges at higher
elevations to the windward that can funnel wind into the
area.

1

MISTLETOE

RATING SYSTEM

INSTRUCTIONS

EXAMPLE

STEP I. Divide live crown into thirds.

STEP 2. Rate each third separately,
Each third should be given a
rating of 0, I or 2 as described
below.

(0) No visible infections.

(1) Light infection (1/2 or
less of total number of
branches in the third infected).

(2) Heavy infection (more
than 1/2 of total
number of branches n
the third infected).

STEP 3. Finally, add
ratings of thirds to
obtain rating for
total tree.

If this third has no visible
infections, its rating is (0).

If this third is lightly infected,
its rating is (I).

If this third is heavily
infected, its rating is (2)

The tree in this example
will receive a rating of
0+1 + 2 ' 3.

The average stand rating can be estimated by determining the
percentage of trees infected in the stand. The approximate
relationship of average stand rating to proportion of trees
infected in mature stands is shown below:

Average stand Percent of trees
mistletoe rating infected

1

50

2

70

3

90

4

97

5

99

6

100

2

TREE

VIGOR

CLASSES

Ctess A Ctess S Ctess C Ctess D

A. VIGOR CLASS A

1. Crown area: 30 percent or more of the "extreme
outline" of vigor class A.

2. Crown length: 50 percent or more of the bole
length.

3. Crown vigor: Dense, full, good color, pointed.

B. VIGOR CLASS B

1. Crown area: Usually more than 30 percent but less
than 50 percent of the "extreme outline" of vigor
class A.

2. Crown length: Usually more than 50 percent but
usually less than 60 percent of the bole length.

3. Crown vigor: Moderately dense, good color, pointed
or slightly rounded.

C. VIGOR CLASS C

1. Crown area: 15 to 30 percent of the "extreme
maximum" of vigor class A.

2. Crown length: 40 to 50 percent of the bole length
except for trees with above- average vigor when 20
percent of the bole length is sufficient.

3. Crown vigor: Sparse, bunchy, poor color, never
pointed.

D. VIGOR CLASS D

1. All live trees of poorer vigor than class C.

Includes trees in classes A, B, and C outlines but
with dead or dying tops.

3

SINGLE- STORY

A. STAND DESCRIPTION

1. May appear to be even-aged, but often contains more
than one age class, occasionally may even be broad-
aged.

2. Codominants form the general level of the canopy, but
the difference in height between dominants, codomi-
nants and intermediates is not as great as in spruce-
fir stands.

3. If even-aged in appearance: (a) There is a small
range in diameter classes and crown length. (b) Live
crown length of dominants and codominants is gener-
ally short to medium (30 to 60 percent of the total
tree height and boles are generally clear for 10 to
40 percent of total tree height) . (c) There are few
coarse- limbed trees in the stand.

4. With two or more age classes, the younger trees
usually have finer branches, smaller diameters,
longer live crown and less clear bole than older
trees .

5. Stocking is generally uniform.

6. Usually does not have a manageable stand of advanced
reproduction.

7. In mixed stands, the overstory is either (a) pure pine
or (b) pine and Engelmann spruce, subalpine fir or
Douglas-fir, with advanced reproduction of species
other than pine that may or may not be a manageable
stand.

4

B. SUGGESTED CUTTING PRACTICES

These stands are usually the least windfirm because the trees have
developed together over long periods of time and mutually protect
each other from the wind.

1. Low windfall risk situations

a. The first cut can remove about 30 percent of the basal area
on an individual tree basis. This first entry is an inter-
mediate cut that resembles the first step of a three-cut
shelterwood since it probably does not open up the stand
enough for pine reproduction to become established in sig-
nificant numbers. Overstory trees are all about equally
susceptible to blowdown, therefore, the general level of the
canopy should be maintained by removing some trees in each
overstory crown class. The cut should come from C and D
vigor class trees, but avoid cutting openings larger than one
tree height in diameter by distributing the cut over the en-
tire area. In mixed stands, if the overstory is pure pine,
handle as a pure stand, but if the overstory is of mixed
composition, cut as much of the pine as possible (without
exceeding the percentage of basal area recommended) to
release the climax species.

b. The usual uniform arrangement of individual trees in single-
storied stands is not well adapted to removing trees by
group selection cutting. Occasionally, however, natural
openings do occur when stands begin to break up. Further-
more, small openings may be desirable to meet management
objectives. An alternative to removing trees on an indi-
vidual basis would be to remove about 30 percent of the
basal area in groups. Openings should be kept small — not
more than 1 to 2 times tree height in diameter — and not
more than one-third of the area should be cutover at any

one time. This kind of cutting should be used only in stands
where insect and disease problems are minimal.

2. Moderate windfall risk situations

a. The first cut should be limited to a light intermediate
cutting that removes about 10 to 20 percent of the basal
area on an individual tree basis. The objective is to
open up the stand enough to allow the remaining trees to
develop windf irmness , but provision should be made to sal-
vage blowdowns. This type of cutting resembles a sanitation
cut in that the lowest vigor and poorest risk trees should
be removed, but it is important that the general level of
the overstory canopy be maintained intact. Mixed stands
should be handled the same as in low wind risk situations,
except that less basal area will be removed.

3. High windfall risk situations

a. The choice is limited to removing all trees or leaving
the stand uncut. Cleared openings can be up to about 5
acres interspersed with uncut areas. Cutover areas should
not exceed about one- third of the total.

5

TWO- STORY

A. STAND DESCRIPTION

1. May appear to be two-aged, but can contain more than two
age classes.

2. Top story — dominants, codominants and intermediates
resembles a single-storied stand.

3. Second story is composed of younger trees of smaller
diameter — small saw logs, poles or saplings — than
top story, but is always below and clearly dis-
tinguishable from the overstory. Trees in the
second story are overtopped but may not be suppressed.

4. If more than two-aged, the overstory usually contains at
least two age classes. The younger trees are finer
limbed and may be smaller in diameter than the older
trees. Second story may also contain more than one age
class .

5. Stocking of overstory may be irregular, but overall
stocking is usually uniform.

6. Usually does not have a manageable stand of advanced
reproduction.

7. In mixed stands, overstory is usually pure pine, but
occasionally may be pine and spruce or Douglas-fir.
Second story is usually spruce and fir at higher
elevations and Douglas-fir at lower elevations.

8. Stocking in mixed stands may vary from uniform to
irregular .

9. Mixed stands often have a manageable stand of advanced
reproduction of species other than pine.

6

B. SUGGESTED CUTTING PRACTICES

Trees in the top story are usually more windfirm than those in a
single-storied stand. Trees in the second and third stories are
usually less windfirm than trees in the top story.

1. Low windfall risk situations

a. The first cut can remove up to 40 percent of the basal area
in three-storied stands (providing not more than half of the
basal area removed comes from the top story) . This cutting
is as heavy as the first or regeneration cut of a two-cut
shelterwood, but marking follows the rules for individual
tree selection. Trees removed should be in vigor classes C
and D insofar as possible, but since the top story is likely
to be more windfirm, selected dominants and codominants
should be left even when they are in vigor classes C and D,
if they do not have dead or dying tops. Avoid cutting holes
in the canopy larger than one tree height in diameter by
distributing the cut over the entire area. In mixed stands,
if the top story or the first and second stories are pure
pine, handle as a pure stand. If the top story is of mixed
composition, cut as much of the basal area to be removed in
pine as is possible and release the climax species, but do
not cut all of the pine if it is needed to maintain the
overstory .

b. In pure or mixed stands with irregular stocking, an alter-
native first cut can remove about 40 percent of the basal
area in a modified group selection. The group openings can
be larger (2 to 3 times tree height) than in single-storied
stands, but the area cutover should not exceed about one-
third of the total. Openings should be irregular in shape
without wind-catching indentations in the borders. This
kind of cutting is not applicable in pure stands where moun-
tain pine beetle or dwarf mistletoe impose limitations be-
cause the interval between initial cutting and final har-
vest is likely to be too long to prevent serious mistletoe
infection of new reproduction and/or loss of beetle-
susceptible trees.

2 . Moderate windfall risk situations

a. The first cut should be an intermediate harvest that

removes not more than 30 percent of the basal area on an
individual tree basis. Predominants , and codominants and
intermediates with long live crowns should be removed.
Maintain the general level of the canopy by not cutting
holes larger than one tree height in diameter in the can-
opy. Provision should be made to salvage blowdowns. Mixed
stands should be handled as in low wind risk situations
except that less basal area will be removed.

3. High windfall risk situations

a. The choice is limited to either removing all the trees or
leaving the stand uncut. Cleared openings can be up to
about 5 acres, interspersed with uncut areas. The cutover
area should not exceed about one- third of the total.

7

THREE-STORY

A. STAND DESCRIPTION

1. May appear three-aged; can contain more than three age
classes, but is seldom broad-aged.

2. Top story resembles a single- storied stand except that
there are fewer trees.

3. Second and third stories consist of younger, smaller
diameter trees. Second story may be small saw logs or
large poles, while the third story is like to be com-
posed of small poles or saplings. Second and third
stories are overtopped, and some trees may be suppressed.

4. Overall stocking is likely to be uniform, but stocking
of any story may be irregular.

5. Usually does not have a manageable stand of advanced
reproduction.

6. In mixed stands the top story may be either pure pine

or a mixture of pine and other species. Second story is
usually spruce and subalpine fir at higher elevations,
or Douglas-fir at lower elevations. May occasionally
contain some pine, but is rarely pure pine. Third
story is almost always composed of species other than
pine.

7. Stocking in mixed stands can vary from uniform to
irregular .

8. Mixed stands often have a manageable stand of advanced
reproduction of species other than pine.

8

B. SUGGESTED CUTTING PRACTICES

Trees in the top story are usually more windfirm than those in a
single-storied stand. Trees in the second story are usually less
windfirm than trees in the top story.

1. Low windfall risk situations

a. The first cut can remove up to 50 percent of the basal area
in two-storied stands (providing not more than half of the
basal area removed comes from the top story) . This cutting
is as heavy as the first or regeneration cut of a two-cut
shelterwood, but marking follows the rules for individual
tree selection. Trees removed should be in vigor classes C
and D insofar as possible, but since the top story is likely
to be more windfirm, selected dominants and codominants
should be left even when they are in vigor classes C and D,
if they do not have dead or dying crowns. Avoid cutting
holes in the canopy larger than one tree height in diameter
by distributing the cut over the entire area. In mixed
stands, if the top story or rarely the first and second
stories are pure pine, handle as a pure stand. If the top
story is of mixed composition, cut as much of the basal area
to be removed in pine as is possible and release the climax
species, but do not cut all of the pine if it is needed to
maintain the overstory.

b. In pure or mixed stands with irregular stocking, an alterna-
tive first cut can remove about 40 percent of the basal
area in a modified group selection. The group openings

can be larger (2 to 3 times tree height) than in single-
storied stands, but the area cutover should not exceed
about one- third of the total. Openings should be irreg-
ular in shape without wind-catching indentations in the
borders. This kind of cutting is not applicable in pure
stands where mountain pine beetle or dwarf mistletoe
impose limitations, because the interval between initial
cutting and final harvest is likely to be too long to pre-
vent serious mistletoe infection of new reproduction and/
or loss of beetle-susceptible trees.

2. Moderate windfall risk situations

a. The first cut should be an intermediate harvest that re-
moves not more than 30 percent of the basal area on an
individual tree basis. Predominants , and codominants
and intermediates with long live crowns should be re-
moved. Maintain the general level of the canopy by not
cutting holes larger than one tree height in diameter
in the canopy. Provision should be made to salvage blow-
downs. Mixed stands should be handled as in low wind
risk situations except that less basal area will be
removed.

3. High windfall risk situations

a. The choice is limited to either removing all the trees or
leaving the stand uncut. Cleared openings can be up to
about 5 acres interspersed with uncut areas. The cutover
area should not exceed about one- third of the total.

9

MULTI- STORY

A. STAND DESCRIPTION

1. Usually broad-aged with a wide range in diameters.

2. If stands developed from relatively few individuals
following disturbance, the overstory trees are coarse-
limbed. Fill-in trees are better formed and finer
limbed. Vigor of overstory trees varies from poor to
good .

3. In stands that developed from deterioration of single-
or two-storied stands, the overstory trees may be no
limbier than the fill-in trees. Nearly all of the
healthy, faster growing trees are below saw log size.

4. Stocking may be irregular.

5. May have a manageable stand of advanced reproduction.

6. In a mixed stand, the overstory may be pure pine or
either pine, spruce and fir at higher elevations or
pine and Douglas-fir at lower elevations. Understory
trees have the same characteristics as pure stands
except that the composition is likely to be species
other than pine.

7. Stocking in mixed stands is more likely to be irregular.

8. Mixed stands frequently have a manageable stand of
advanced reproduction of species other than pine.

10

B. SUGGESTED CUTTING PRACTICES

These are usually the most windfirm stands> even where
they have developed from the deterioration of single-
and two-storied stands. By the time they have reached
their present condition, the remaining overstory trees
are likely to be windfirm.

1. Low to moderate windfall risk situations

a. There is considerable flexibility in harvest-
ing these stands. All size classes can be cut
with emphasis on either the largest or smallest
trees in the stand. The first cut can range from
an overwood removal to release the younger grow-
ing stock _to_ a thinning from below to improve the
spacing of the larger trees. Thereafter cutting
can be directed toward either even-aged or uneven-
aged management. In mixed stands the first cut
should be an overwood removal of the pine to
release the climax species. The under story
trees should be thinned to improve spacing.

2. High windfall risk situations

a. The safest first cut is an overwood removal with a
light thinning from below to obtain a wider spaced,
more open stand that can develop windf irmness .
Thereafter, cutting can be directed toward either
uneven- or even-aged management.

11

A. MODIFICATION OF SUGGESTED CUTTING PRACTICES IMPOSED BY

DISEASE AND INSECT PROBLEMS

1. Dwarf mistletoe

a. Cut only in stands where the average mistletoe
rating is 2 or less, (or less than about two-
thirds of the trees are infected) and remove only
the percentage of basal area recommended for the
stand description and windfall situation. In
single-storied stands, where site index is 70 or
above, trees in the intermediate and lower crown
classes should be removed in preference to domi-
nants and codominants. If site index is below
70, trees in all crown classes are about equally
susceptible to infection. In two- and three-
storied, as much of the cut as possible should
come from the second and third stories because
these trees are likely to be more heavily infected
than the top story. To minimize infection to new
reproduction in single- , two- and three-storied
stands, the final overstory removal should be made
within 30 years after the regeneration cut when the
average mistletoe rating is 1, and within 20 years
when the rating is 2. Provision should be made to
sanitize the young stand at the time of final harvest.
In multi-storied stands, the safest procedure is an
overwood removal with a cleaning and thinning from
below.

b. In old-growth stands with an average mistletoe
rating of greater than 2, any partial cutting,
thinning or cleaning is likely to intensify the
infection. The safest procedure, therefore, is
to either remove all trees and start a new stand
or leave the stand uncut. If the manager chooses
to make a partial cut for any reason, the initial
harvest should be heavy enough to be a regeneration
cut. All residual trees must be removed within 10
years after the first cut, and provision made to
sanitize the young stand at that time.

2. Comandra blister rust

a. Cut as many trees with stem cankers and spiketops
as possible without removing more than the recom-
mended basal area or cutting large openings in the
canopy. Since the rate of spread in mature trees
is relatively slow, and the disease is not trans-
mitted from pine to pine, leaving a few infected
trees is less of a risk than opening up the stand
too much.

12

3. Mountain pine beetle

a. If the insect is present in the stand at an
endemic level, or in adjacent stands in suffi-
cient numbers to make successful attacks and:

(1) Less than the recommended percentage of basal
area to be removed is in susceptible trees,
any attacked tree and all of the most suscepti-
ble trees should be removed in the first cut.
This will include most of the trees 14 inches
d.b.h. and larger, and all trees 10 to 14
inches d.b.h. in vigor classes A and B. Pro-
vision should be made to salvage attacked trees,
and a second cut should be made in about 10 years
after the first cut.

(2) More than the recommended percentage of basal
area to be removed is in susceptible trees, the
manager has three options: (1) remove all the
trees, (b) remove the recommended basal area

in attacked and susceptible trees and accept
the risk of future losses> or (c) leave the stand
uncut. If the stand is partially cut or left un-
cut, some trees from 7 to 12 inches d.b.h. and
most trees below 7 inches d.b.h. will survive
all but epidemic outbreaks.

b. If the stand is presently sustaining an infestation
that is building up, and the manager chooses to
either partially cut or leave the stand uncut, he
must accept the risk of an outbreak that could
destroy most of the merchantable stand.

Agriculture— CSU, Ft. Collins

13