REPRODUCING JACK PINE BY
THE SHELTERWOOD METHOD [N
NORTHERN LOWER MICHIGAN

Thesis for the Degree of M. S.
MECHIGAN STATE UNIVERSITY
EDWARD WEBSTER CAVENEY, TR.
1969

ABSTRACT

REPRODUCING JACK PINE BY THE SHELTERWOOD
METHOD IN NORTHERN LOWER MICHIGAN

BY

Edward Webster Caveney, Jr.

Since the beginning of forest management in Michi-
gan, reproducing jack pine has been a problem. Jack pine
is a fire species, and with the exclusion of wild fires,
regeneration of the species must be accomplished by other
means.

For over 10 years the Forestry Division of the
Michigan Department of Natural Resources has been using a
2-cut shelterwood method to regenerate many of the jack
pine stands in northern Lower Michigan. No formal evalua-
tion of this method was made until this study was
undertaken.

The objective of this study was to evaluate the
shelterwood method as it was being used by the Forestry
Division of the Michigan Department of Natural Resources
to regenerate jack pine. To accomplish this, 42 stands
were examined in Otsego, Kalkaska, Crawford, Oscoda, and

Ogemaw Counties in central northern Lower Michigan.

Edward Webster Caveney, Jr.

The following data were recorded for each stand:
(1) soil type, (2) stand age when cut, (3) date cut, (4)
volume removed, (5) skidding equipment, (6) cutting speci-
fications (7) residual basal area, (8) ground cover, and
(9) reproduction. Within each stand, a residual basal
area plot was taken every 4 chains, and 5 mil-acre plots
were taken at each residual basal area plot. In the 42
stands, 623 basal area plots and 3,115 mil-acre plots were
taken.

Thirty-six percent of the mil-acre plots were
stocked with jack pine. The individual stands varied be-
tween 8 percent and 67 percent stocked. 0n the average,
there were 754 jack pine seedlings per acre, and for in-
dividual stands this varied from 80 to 2,349 seedlings
per acre.

Twenty-four variables for each stand were used
for multiple regression analysis. Two final prediction
equations were computed; one for predicting percent of
mil-acres stocked with jack pine, and the other for pre-
dicting jack pine seedlings per acre.

Residual basal area of jack pine was found to have
an effect on stocking. High residual basal areas (70
square feet) were found to have highest stocking of newly
established seedlings. However, growth was inhibited by
these high basal areas. Average stocking was highest

under 40 square feet of residual basal area.

Edward Webster Caveney, Jr.

Open-coned trees were found to be very important
in the residual stand. The stocking was increased with
increasing amounts of Open-coned trees.

Both the height of ground cover and its components
had effects on stocking. Stocking was highest where
ground cover was less than 6 inches high and where its
components were mainly reindeer lichen, litter, and green
mosses.

The stocking increased as the number of years
since cutting increased. Stands cut 1 growing season
before the study were only 8 percent stocked, while stands
cut 9 years before the study were 55 percent stocked.

Many stands were found to be converting to low
quality oak. It was determined that this conversion could
be greatly reduced, if not stopped, by the removal of the
oak as soon as possible in the life of the stand.

The shelterwood method accomplishes quite well the
multiple-use objectives of the Forestry Division. This
method fits in well with the wildlife management and rec-
reational management objectives.

The shelterwood method seems to be well adapted to
reproducing jack pine in northern Lower Michigan. If more
Open-coned trees are retained in the seed cut, the percent
of open-coned trees can be expected to increase in future
stands which will make this method even more successful

than it has been in the past.

REPRODUCING JACK PINE BY THE SHELTERWOOD

METHOD IN NORTHERN LOWER MICHIGAN

BY

Edward Webster Caveney, Jr.

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Forestry

1969

ACKNOWLEDGMENTS

I am grateful to the following for the assistance
given during the course of this study: To Dr. V. J.
Rudolph, who devoted considerable time in guiding and re-
viewing the study methods, and the critical reviews and
discussions during the preparation of the thesis; to Dr.
C. Cress for the invaluable assistance given concerning
all statistical problems; to the Michigan Department of
Natural Resources for financing the data—gathering period
of this study; and to Michigan State University for finan—
cial aid in the form of an assistantship in the Department
of Forestry, and for providing the needed supplies and
facilities used during the preparation of this thesis.
Finally, I am grateful to my wife, Terry, for her assistance

in all phases of this study.

ii

TABLE OF CONTENTS

Page
LIST OF TABLES O O O O O O O I O O O O O 0 O O O O 0 iv

LIST OF FIGURES o o o o o o o o o o o o o o o o o 0 Vi

INTRODUCTION . . . . . . . . . . . . .‘. . . . . . . 1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . 3
STUDY AREA . . . . . . . . . . . . . . . . . . . . . 9
FIELD PROCEDURES . . . . . . . . . . . . . . . . . . 11
RESULTS AND DISCUSSION . . . . . . . . . . . . . . . 14

The Shelterwood Method and Multiple Use
Management . . . . . . . . . . . . . . . . . . 47

SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . 48
LITEMTURE CITED 0 O O O O O O O O O O O O O O O O O 53

APPENDIX 0 O O O O O I O O O O O O O O O O O O O O O 55

iii

Table

10.

11.

12.

LIST OF TABLES

Summary of data for all stands . . . . . .

Jack pine stocking, by mil-acres stocked,
and seedlings per acre . . . . . . . .

Regression coefficients for the percent of
mil-acre plots stocked with jack pine
(LSDEL routine) I O O O O O O O O O O 0

Regression coefficients for the percent of
mil-acre plots stocked with jack pine
(LSDEL routine) . . . . . . . . . . . .

Regression coefficients for the number of
jack pine seedlings per acre (LSDEL
routine) I O O O O O I O O O O O I O 0

Regression coefficients for the number of
jack pine seedlings per acre (LSDEL
routine) . . . . . . . . . . . . . . .

Regression coefficients for the number of
red oak seedlings per acre (LSDEL
routine) I O O I O O O O O O O O O O 0

Jack pine reproduction stocking on various
SOil types 0 O O O O O O O O O O O O 0

Jack pine stocking following cutting under
three different cutting specifications

Jack pine stocking as affected by skidding
equipment used . . . . . . . . . . . .

Stocking with other reproduction in addition

to jack pine . . . . . . . . . . . . .

Jack pine stocking under varying residual
basal areas of jack pine . . . . . . .

iv

Page

15

16

19

21

23

25

28

28

30

31

31

33

Table Page
13. Jack pine stocking under varying residual
basal areas of open-coned trees . . . . . . 34

14. Effects of ground cover on jack pine
StOCking I O O O O I O O O I O O I O O O O 36

15. Jack pine stocking with various ground
cover conditions . . . . . . . . . . . . . 36

LIST OF FIGURES

Figure
1. Michigan's lower peninsula showing the
study area and the townships involved
in the S tudy O O O O O O O O O O O O

2. Jack pine stocking by year of cutting .

3. A mature jack pine stand showing the clumpy

nature of the residual stand . . . .

4. A jack pine area in Crawford County 2 years

after clearcutting . . . . . . . . .

5. A clearcut area with buffer strip along
the road O O O O O O O O O O O O O O

6. A jack pine stand 9 years after being cut

by the shelterwood method . . . . .

7. Stand number 39 in Ogemaw County 5 years
after a shelterwood cutting . . . .

vi

Page

10

38

4O

42

43

44

45

INTRODUCTION

Jack pine1 is a very important species in the
forests of Michigan. In the State Forests of northern
Lower Michigan, the jack pine type occupies 252,000 acres,
just over 14 percent of the total forest area.

The demand for jack pine timber is very good. The
stumpage prices in some areas of northern Lower Michigan
are over $4.50 per cord. In this same area the demand
for jack pine is greater than the allowable cut. There-
fore, it is desirable to increase the production of jack
pine.

Ever since Michigan's forests began to be managed,
regenerating jack pine has been a problem. During and
after the logging of the virgin timber, forest fires
burned across Michigan unchecked. As jack pine is a "fire
species," its area increased. Forest fires are now infre-
quent, and other methods of regenerating jack pine must be
used.

Almost every silvicultural method of regenerating
jack pine has been tried with varying degrees of success.

For over 10 years, the Michigan Department of Natural

 

1Scientific names of species encountered in this
study are listed in Appendix 1.

l

Resources has been using a form of the shelterwood method
for regenerating many stands in the State Forests of
northern Lower Michigan. Since no formal evaluation of
this method had been made, this study was begun in the
summer of 1968.

The objectives of this study are to evaluate the
shelterwood method for regenerating jack pine in Michigan's
Lower Peninsula, to determine its success, and to analyze
the effects various conditions have on the stocking that
is obtained. Based on the results, recommendations are
made as to the suitability of the shelterwood method for

regenerating jack pine under various conditions.

REVIEW OF LITERATURE

Jack pine is a short-lived, small to medium tree.
Its range extends from northern New England to the Lake
States and across Canada to the foothills of the Rockies.
It is the most northern American pine (17).

Jack pine is a pioneer species and is adapted to
growing on very dry sandy or gravelly soils where other
species have difficulty surviving. However, it grows best
on well-drained loamy sands where the mid-summer water
table is 4 to 6 feet below the surface (17).

Over most of its range, jack pine bears serotinous
cones which Open only after being subjected to high tem-
peratures. The melting point of the bonding material at
the tips of the cone scales is 122°F (50°C) (5).

The serotinous nature of jack pine apparently
varies with the age of the stand as well as with the
locality. Greater seed dispersal has been noted in 20-
year-old stands than in 40- or 60-year-old stands. The
4-year average seedfall in the younger stands was 147,000
seeds per acre and 35,000 seeds per acre in the older
stands (7). Along the southern edge of its range, jack
pine bears nonserotinous cones which promptly open upon

ripening and disperse their seeds during September or

3

October (17). In a seed source test plantation, open—
coned trees appeared most frequently in sources from Lower
Michigan, southern and western Minnesota, New Brunswick,
and Maine (15).

The results of a one parent progeny test demon-
strate that the open-coned characteristic is highly
heritable, in that the progenies derived from open polli-
nated, Open-coned mother trees showed a cone type ratio
of 1 closed : 2 open : 1 mixed (14). This indicates that
if only open-coned trees are favored, their percentage
can be increased from very little to 50 percent in one
generation.

The effective range of jack pine seed dissemina-
tion is about 2 tree heights. However, beyond 1 tree
height, it is relatively low (17).

Jack pine seed usually germinates within 15 to 60
days after dissemination. The highest survival follows
germination in the early spring (17).

Several studies have demonstrated that shade is
an important factor in reducing mortality caused by heat
and drought. Germination decreases significantly if seeds
are exposed to sunlight for more than 4 hours per day,
probably as a result of higher temperature and reduced
surface moisture (10). The survival of l- and 2-year-old
seedlings was 29 to 33 percent and growth was 1 to 2 inches

in the Open, compared to 62 to 77 percent and 2 to 5 inches

under 56 percent full sunlight (17). A study in Michigan
found that shade definitely improved germination and early
survival of seedlings (3).

Seedling establishment is best on mineral soil.
In the Lake States, the chances that a seed will germinate
and the seedling survive 2 years, is 9 to 12 times as
great on mineral soil as on undisturbed soil (17). The
reason humus is usually such a poor seedbed can be ex-
plained in terms of moisture relations. A study in Mani-
toba compared germination and early develOpment on three
types of seedbeds--mineral soil, mixed mineral soil, and
humus-—on fresh to moderately moist soils. In years of
above normal precipitation, all three seedbeds were
favorable (7).

Seedling growth is very slow for the first 3 years,
and then increases rapidly the fourth and fifth years (1).
The average heights of wild seedlings is 2 inches at 1
year, 6 inches at 2 years, and l to 3 feet at 4 years (17).

Jack pine is a very intolerant species, yet young
seedlings can exist in light as low as 2.4 percent full
sunlight. Under mature jack pine stands, seedlings are
most frequent and abundant in light intensities of 11 to
30 percent of full sunlight, but greatest height growth is
obtained in 52 percent of full sunlight (17). As was
pointed out before, shade is an important factor in early

survival of jack pine seedlings. The amount of shade

seems to have little effect. It is believed that the
complex shade patterns cast by slash and snags on burned-
over areas contribute substantially to the densely stocked
stands that result (7).

Most fully stocked natural jack pine stands of
today are the result of wild fires (1?). The crowns of
the dead trees in a natural stand that has burned provide
both seed and shade (8). There are from 400,000 to
2,000,000 seeds stored in the cones on an acre of mature
jack pine (8,17). The shade provided by the dead crowns
is beneficial for germination and establishment by giving
protection from high temperature and excessive moisture
loss (1,3,7).

Burning will not bring about jack pine regenera-
tion from seed in slash. If the fire is hot enough to
prepare the seedbeds and Open the cones, the seed in the
slash is destroyed. Therefore, enough trees must be left
after the harvest to reseed the area (1,3,7). As many as
75 trees per acre may need to be left (19).

Jack pine can be successfully regenerated by fire
if the depth of the humus is substantially reduced by
burning, and the seedbeds created are adequately seeded
(3,7).

The traditional clearcut method of cutting the
trees and piling the slash does not result in adequate

regeneration in many instances (7,9,11). 0n five clearcut

areas in Canada, the range in stocking was 2 to 16
percent (7).

For success with the clearcutting method, there
are two additional treatments which must be applied.
First, the site must be scarified with something like an
Athens disk to prepare a seedbed. Second, the cone-
bearing slash must be scattered over the area in such a
way that the cones are within 1 foot of the ground (4,7,
8,9,11). Higher temperatures are reached near the ground
so the cones readily open and disperse their seed (4,7,17).
In a Minnesota stand which was disked, logged, and the
slash scattered, the stocking was 45 percent after 5 years
(4). The Society of American Foresters suggests that un-
less 40 percent or more of the area is adequately stocked
at the time of harvest, soil scarification or planting
should be considered (16).

It is believed by some foresters that clearcut
strips could be an improvement over clearcutting large
areas, if the strip width and strip direction are properly
chosen to suit the site and local climate. In one study,
out strips 66 feet wide, with 132 feet uncut between the
strips, resulted in 45 percent stocking (11). In a study
in Manitoba where clearcutting, seed tree cutting, and
strip cutting were compared, the best results were obtained
with strip cutting. At the end of 3 years, 14 percent of

the mil-acres sampled were stocked (7).

A specific comment on using the shelterwood method
to regenerate jack pine comes from Barrett (2, p. 108),
where he recommends what appears to be a 2-cut shelterwood:

A decision as to harvest method will be affected by
the relative abundance of serotinous and Open cones
present on the trees. If Open cones predominate, a
seeding cut may be made about 5 years in advance of
the final harvest cut. This should remove over half
the total volume, leaving the larger-crowned trees
with good cone crops. The final harvest should be
made as a clearcutting as soon as regeneration is
established.

STUDY AREA

The study area included State Forest lands in

Otsego, Kalkaska, Crawford, Oscoda, and Ogemaw Counties in
central northern Lower Michigan (Figure l). The townships
from within these counties were selected by the regional
and district foresters of the Forestry Division, Michigan
Department of Natural Resources, and included T32N, R1W

in Otsego County; T27N, R5W in Kalkaska County; T25N, R4W
and T27N, R1W in Crawford County; T28N, RlE and T27N, R2E
in Oscoda County; and T24N, RlE in Ogemaw County. Within
these seven townships, all stands that had been partially
cut between 1958 and 1966 with the objective of regenerat-
ing them were included in the study. Several stands could
not be used because they had been burned or the residual

basal area had been cut.

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2

Michigan's lower peninsula showing the study

area, and the townships involved in the study.

FIELD PROCEDURES

For every stand included in the study, the follow-
ing information was gathered:

1. Location

2. Acreage

3. Soil type

4. Age of stand at time of cutting

5. Date of cutting

6. Volume removed per acre

7. Logging equipment used

8. Cutting specifications
Most of this information was available on the timber cut—
ting permit in the files at the Office of each State
Forest. Information on the logging equipment was obtained
during interviews with the Forestry Division Area Foresters
and technicians. The age of the stand at the time of cut-
ting was determined by boring residual trees and subtract-
ing the time since cutting from the total age. Ring
counts were also made on several stumps in each stand.

Within the stand, BAF 10 residual basal area point
samples and mil-acre plots were taken. Every 4 chains
within each stand, the residual basal area of jack pine

and any other species was recorded on a point sample.

11

12

Also recorded was the basal area of any jack pine mortality
that had occurred since the cutting. Basal area of open-
coned. (nonserotinous) 'trees was recorded. Basal areas
were determined using a wedge prism.

At every residual basal area point sample, 5 mil-
acre plots were taken to sample reproduction, which was
recorded in three height classes: less than 1 foot, 1 to
3 feet, and over 3 feet. Also recorded on each mil-acre
plot was the percent of ground cover, its major components,
and its height by one of three height classes: less than
6 inches, 6 to 18 inches, and over 18 inches.

A 5-foot aluminum pole was used to mark the center
of each mil-acre plot. A meter stick with a woven wire
lOOp on one end was used to determine mil-acre plot bound-
aries. One mil-acre plot was established at the center of
the basal area plot and the other four were one-quarter
chain north, east, south and west of the basal area plot
center.

Data were gathered from 42 stands, in which 623
basal area point samples and 3,115 mil-acre plots were
taken.

The following stocking guide set forth by Candy

(6) was used to evaluate reproduction in this study:

l3

 

 

Stocking Class Stockedguadrats
Percent
Fully Stocked 80 to 100
Well Stocked 60 to 79
Moderately Stocked 40 to 59
Under Stocked 20 to 39

Failure Less than 20

RESULTS AND DISCUSSION

Results for the 42 stands are presented in Table
1. It is Obvious that some stands regenerated very well
and some very poorly. The data that are of the most in-
terest are the percentages of mil-acres stocked with jack
pine, and the average number of jack pine seedlings per
acre. Of the 3,115 mil-acre plots taken, 1,119 or 36 per-
cent were stocked with jack pine. There were 2,349 jack
pine seedlings on the 3,115 plots, for an average of 754
seedlings per acre.

If the 42 stands are classified by Candy's (6)
guide, there are 2 well stocked, 13 moderately stocked,

20 under stocked and 7 failures. The distributions of
the stands by both percentage of mil-acres stocked, and
jack pine seedlings per acre are given in Table 2.

Data for each stand and mil-acre plots were punched
into computer cards and processed by three computer rou-
tines. The stand data were processed by the least squares
(LS) and the least squares delete (LSDEL) routines. Then
the data from the 3,115 mil-acre plots were processed to
determine for each variable the percent of plots stocked

with jack pine reproduction.

l4

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usu Ou waum: uouomus uszmuU n.m Occm OCHwauo em mm NO OOH OH five om vm O Hm H .ZFNE
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ocanme nw>osom mac OOH: cqu
DEDHO> Ocmuw
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muOHm HaanmOm
Omwuw><

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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.H SHAME

16

Table 2.--Jack pine stocking, by mil-acres stocked, and
seedlings per acre.

 

 

Mil-Acres Stocked

 

 

 

with Jack Pine Number of Stands
Percent
0 to 20 7
21 to 30 10
31 to 40 ll
41 to 50 11
51 to 70 3
23
Jack Pine Seedlings
Per Acre Number of Stands
Number
0 to 300 7
301 to 600 11
601 to 900 13
901 to 1,200 8
1,201 to 2,500 3

 

17

Data for the following 24 variables were used for

each stand:

1.

10.
ll.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.

Percentage of mil-acres stocked with jack
pine.

Total residual basal area in square feet per
acre.

Residual basal area of jack pine in square
feet per acre.

Residual basal area of open—coned jack pine in
square feet per acre.

Residual basal area of red pine in square feet
per acre.

Residual basal area of white pine in square
feet per acre.

Residual basal area of aspen in square feet
per acre.

Residual basal area of red oak in square feet
per acre.

Residual basal area of jack pine mortality in
square feet per acre.

Jack pine seedlings per acre.

Red pine seedlings per acre.

White pine seedlings per acre.

Aspen sprouts per acre.

Red oak seedlings per acre.

Red maple seedlings per acre.

Number of years since stand was cut.

Age of the stand when cut.

Location: T32N, R1W

Location: T27N, R5W

Location: T25N, R4W

Location: T27N, R1W

Location: T28N, RlE

Location: T27N, R2E

Location: T24N, RlE

The first analysis had as its dependent variable

the percentage of mil-acre plots stocked with jack pine.

The least squares (LS) routine showed that 80 percent of

the variability could be explained by all 22 variables.

(Because the variables mil-acre plots stocked with jack

pine and jack pine seedlings per acre were so closely re-

lated, they were used only as dependent variables.)

18

When the location variables were drOpped from the model,
the resulting variability accounted for was 71 percent.
Therefore, the variability explained by location is 9
percent.

Next, the least squares delete (LSDEL) routine was
used for the remaining 15 variables, so that it would de-
lete those variables, one at a time, that could not meet
the 10 percent minimum significance. This procedure re-
tained 9 variables, accounting for approximately 67 percent
of the variability (Table 3).

There are two variables in this grouping which
make a prediction equation impractical for use in the field.
These are red pine seedlings per acre and red maple seed-
lings per acre. Since the study plots were taken several
years after cutting, the red pine and red maple seedlings
would not be present to measure in a newly cut stand. Also,
a forester might find it too time consuming to take repro—
duction plots. Unfortunately, these two variables are
quite important in accounting for the variability. I be-
lieve the reason for this is the similarity in sites and
environment favorable for red pine and jack pine reproduc-
tion, and the dissimilarity in sites and environment
favorable for jack pine and red maple reproduction.

To develop a formula that would be of practical
use in the field, red pine seedlings per acre and red

maple seedlings per acre were dropped from the model, and

l9

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chm HODn

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20

the following 9 variables were included in the LSDEL
routine: residual basal area; residual basal area of
Open-coned trees; residual basal area of jack pine, red
pine, white pine, aspen, and red oak; residual basal area
mortality; and age. The minimum significance was set at

10 percent. One variable, the residual basal area of open-
coned trees, was forced to remain in the model, because
this is the only seed source in a stand and must be con-
sidered when the stand is cut. The variability explained
by all 9 variables was 45 percent. After the deletion, 4
variables remained, accounting for 44 percent of the
variability (Table 4). These variables were residual basal
area of jack pine, residual basal area of Open—coned trees,
residual basal area of white pine, and residual basal area
of mortality. The analysis of variance for the regression
showed this model to be significant at <0.0005.

If a prediction equation with the coefficients for
these variables is used soon after a stand is cut, the ex-
pected value for residual basal area of mortality must be
estimated. From my data, the average mortality was 3.8
square feet per acre, but it varied from 0 to 15 square
feet per acre for the 42 stands. This estimated basal area
of mortality must be subtracted from the actual residual
basal area of jack pine to obtain the value for residual

basal area of jack pine for insertion in the equation.

21

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22

An example of using the prediction equation is as
follows:

Residual basal area of Open-coned _ 15
trees

Residual basal area of jack pine

Residual basal of white pine

Residual basal area of mortality

square feet per acre

40 square feet per acre
square feet per acre
5 square feet per acre

II II II
0

Then:

l4
ll

0.1879 + 15(.0107) + 40(.004l) - 5(.0111)

K
II

46 percent of the mil-acres are stocked
with jack pine

This equation can be used to predict the future stocking
of a recently cut stand.

The next analysis considered jack pine seedlings
per acre as the dependent variable. The 22 variables were
analyzed on the LS routine, and they explained 81 percent
of the variability. When the location variables were
dropped, the remaining variables accounted for 71 percent
of the variability. Thus, the variability attributed to
location was 10 percent.

Next the 15 variables, excluding location, were
analyzed by the LSDEL routine, and they accounted for 71
percent of the variability. The minimum significance was
again set at 10 percent, and the nonsignificant variables
were deleted, leaving the same 9 variables as before. The
9 accounted for 68 percent of the variability. The result-

ing regression coefficients are presented in Table 5.

23

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map How mucOHonmmoo :OHmmOHmmmII.m OHQDB

24

Again, red pine seedlings per acre and red maple
seedlings per acre were included in the 9 significant
variables.v Consequently, an LSDEL was applied to the 9
variables that are easy to measure in an inventory. The
minimum significance was set at 10 percent, and residual
basal area of open-coned trees was forced to remain in the
model. Before deletion, the model explained 41 percent of
the variability, and after deletion, leaving only four
variables, the variability accounted for was 37 percent.
The resulting regression coefficients are presented in
Table 6.

The analysis of variance for the regression showed
this model to be very significant, with an F value of 5.45,
significant at the 0.001 level.

An example of estimating the number of jack pine

seedlings per acre is as follows:

40 square feet per acre

Residual basal area of jack pine

Residual basal area of open-coned
trees

Residual basal area of aspen = 0 square feet per acre

Residual basal area of mortality = 5 square feet per acre

15 square feet per acre

Then:

I-<
ll

158.41 + 40(14.53) + 15(34.46) - 5(31.66)

*4
ll

1,098 jack pine seedlings per acre

This formula can best be used to predict the number of

jack pine seedlings right after a stand has been cut.

25

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26

These models are only applicable to the 2-cut
shelterwood method, as all the data were gathered from
stands treated this way. The prediction equations, how-
ever, should be useful even when a 3-cut shelterwood method
is used. For the preparatory cut, professional judgment
will be the best guide in selecting the trees to leave.

In marking for the seed cutting, the prediction equations
should be helpful in leaving enough of the best trees.

The reproduction information for several stands
indicates that they are converting from the jack pine type
to some other type (Table 1). On the better sites, the
conversion is from jack pine to white pine, red maple, red
pine, aspen, and red oak. Stands numbered 6, 11, and 19
show such conversion underway. On these sites, conversion
is probably desirable, and would be difficult to combat
anyway. However, stands on the poorer sites are convert-
ing to low quality red oak. Examples of this are stands
numbered 7, 21, 22, 23, and 25. From a timber management
standpoint, such conversion is not desirable, since the
oak is of low quality and has little market value. In
these stands, the oak was not cut or treated with a silvicide
at the time of harvesting, so that an oak seed source is
left as well as undesirable competition for jack pine re-
production. This study indicates that any oak not out
should be treated with silvicide or otherwise eliminated

as early as possible in the life of the stand.

27

To demonstrate the importance of removing any
residual basal area of red oak from the stand, I analyzed
the data with the LSDEL routine, with red oak seedlings
per acre as the independent variable. Nine variables
easy to measure were used: total residual basal area, resid-
ual basalarea of jack pine, residual basal area of open
coned trees, residual basal area of red pine, white pine,
aspen, red oak, residual basal area of mortality, and age.
These nine variables accounted for 62 percent of the
variability in red oak seedlings per acre. The minimum
significance was set at 5 percent. After deletion, only
residual basal area of red oak and residual basal area of
red pine were left, and the variability explained was 54
percent. If the residual basal area of red oak were de-
leted, the variability accounted for would drop to 2 per-
cent. The analysis Of variance showed the regression was
significant at the <0.0005 level (Table 7.)

These results show that to maintain the jack pine
type where red oak is a threat, the oak must be removed.
Conditions under an overstory are more favorable for red
oak reproduction than for jack pine because the red oak
has greater tolerance and a greater ability to germinate
and survive on undisturbed sites (17).

The percent of mil-acres stocked with jack pine
reproduction on each soil type encountered in the study

was determined (Table 8). For those soil types on which

28

Table 7.--Regression coefficients for the number of red
oak seedlings per acre (LSDEL routine).

 

 

 

Standard
Partial
Regression Regression a
Variable Coefficient Coefficient Significance
Constant 75.499 --- 0.217
Residual Basal Area
of Red Oak 77.380 0.7350 <0.0005
ReSIdual Basal Area 28.149 0.2601 0.024

of Red Pine

 

a O O O O 0
Minimum Significance: 5 percent.

Table 8.--Jack pine reproduction stocking on various soil

 

 

 

types.
Mil-Acres Stocked
Soil Type Mil-Acres Sampled With Jack Pine
Number Percent
Grayling Sand 2,405 37
Rubicon Sand 485 40
Roselawn Sand 115 7
Emmet 50 32
Saugatuck Sand 35 29

Kalkaska Sand 25 8

 

29

jack pine formed a part of presettlement natural vegeta-
tion as described by Veatch (18), the stocking is above
the average of 36 percent for all plots. The soil types
on which jack pine was not a part of the natural vegeta-
tion include Roselawn, Emmet, Saugatuck, and Kalkaska.

The effect of the season of cutting could not be
determined because most stands were cut during more than one
season, and it was impossible to tell which part of each
stand was cut during which season.

In all stands, cutting specifications had been
imposed to define the residual stand that would be left
after cutting. Three such cutting specifications had been
used: (1) diameter limit, (2) marked to leave, and (3)
marked to cut. In Table 9, reproduction results following
cutting using these specifications are compared.

The stands marked to leave had the least jack pine
reproduction. Stands that were marked to leave averaged
10 square feet per acre less residual basal area than
stands marked to cut. Perhaps not enough trees were marked
to leave, and the best trees to leave were not included.
Also, less residual basal area of Open-coned trees was
left in the stands marked to leave (Table 9). This indi-
cates that if more care were taken in marking the trees
to leave, the jack pine reproduction results would be more

favorable.

30

Table 9.--Jack pine stocking following cutting under three
different cutting specifications.

 

 

Residual Basal
Area per Acre

 

Mil-Acres

 

Cutting Mil-Acres Stocked with Open
SpecifiCation Sampled' Jack Pine Total Coned
Number Percent Sq. Ft. Sq. Ft.

Marked to Cut 1550 41 39.7 10.4
Diameter Limit 510 37 33.1 7.9
Marked to Leave 815 27 29.9 6.6

 

a

Next, the effect of the skidding equipment used in
the logging is examined (Table 10). As can be seen, the
results vary considerably, and are difficult to explain.
The sample was small for those stands that were truck and
horse skidded. This small sample may not be representa-
tive of the situation. Stocking in stands where skidding
was with a wheel tractor is significantly higher than in
stands where a crawler tractor was used. It is believed
that the differing effects of skidding would be caused by
different amounts of site disturbance. This may be influ-
enced more by how the wood was moved rather than what
machine moved it. More mineral soil would be exposed if
the wood was dragged rather than moved on a trailer, and
this information was not available. In truck skidding, the
truck was driven through the stand and the wood was loaded

directly onto the truck.

31

Table 10.--Jack pine stocking as affected by skidding
equipment used.

 

 

 

Skidding Mil-Acres Mil-Acres Stocked
Equipment Used Sampled With Jack Pine
Number Percent
Crawler Tractor 1,905 33
Wheel Tractor 545 42
Truck 60 67
Horse 40 48

 

Many plots had reproduction of other species on
them in addition to jack pine (Table 11). Only red pine
and red maple vary enough from the average for all species
to be significant. Conditions and sites that are favorable

for red pine reproduction are also favorable for jack pine,

while conditions and sites favorable for red maple reproduc-
tion are not favorable for jack pine. These same relation-

ships were indicated earlier in the regression analyses.

Table ll.--Stocking with other reproduction in addition to
jack pine.

 

 

 

Reproduction in Mil-Acres Mil-Acres Stocked
Addition to Jack Pine Sampled with Jack Pine
Number Percent
Red Pine 56 65
Red Oak 571 40
White Pine 114 37
Aspen 177 34
Red Maple 58 21
Othera 43 42

 

aIncludes white oak, spruce, balsam fir, and beech.

32

Both the total residual basal area and the residual
basal area of open-coned trees affected stocking with jack
pine reproduction (Tables 12 and 13). The stocking is
given by three seedling height classes to demonstrate the
effect of increasing shade on seedling growth. Adequate
shade is important for the early establishment of jack pine
seedlings, because of decreased competition from ground
cover and more favorable moisture conditions for germina-
tion. However, too much shade is detrimental to seedling
growth.

The amount of residual basal area in open-coned
trees is very important in the establishment of a new
stand as it is the only seed source from which the new
stand can be regenerated. Only stands with 0 or 50 square
feet of residual basal area in Open-coned trees had lower
stocking than the average for all plots (Table 13). The
reason that percent stocking falls off after a residual
open-coned basal area of 30 square feet is that the total
residual basal area is probably in excess of 70 square
feet, which becomes too high for good seedling develOpment.
If only the Open-coned residual basal area had been left,
stocking would most likely have continued to increase. Of
all the plots with Open-coned trees, 40 percent are stocked
with jack pine, while only 30 percent of the plots without
Open-coned basal area are stocked. This again demonstrates
the importance of Open-coned trees as a seed source for

obtaining reproduction.

33

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34

Table 13.--Jack pine stocking under varying residual basal
areas of open-coned trees.

 

 

Residual Basal Area

 

of Open-Coned Trees Mil-Acres Mil-Acres Stocked
per Acre Sampled with Jack Pine
Sq. Ft. Number Percent
0 1,326 - 30
10 1,203 39
20 390 43
30 120 43
40 60 38
50 15 33

 

The open-coned residual basal area is so important
that it would be useful to have a guide to the amount of
open-coned trees to be left to assure reproduction success.
Of the 42 stands examined in this study, 22 of them had 8
or more square feet per acre Of open-coned trees. Of the
22 stands, 16 were above average stocking and 6 were below
average stocking. Of the 20 stands with less than 8 square
feet per acre of Open-coned trees, only 6 were above
average stocking and 14 were below average. From this it
is evident that at least 8 square feet of basal area in
Open-coned trees should be left per acre to obtain reason-
able success.

A major competitive factor in the germination and

establishment of jack pine is ground cover. In this study,

35

three items of information were obtained for the ground
cover on each plot: (1) percentage of area covered by
ground cover, determined by ocular estimation; (2) maxi-
mum height of ground cover on the plot; and (3) the major
components or species of ground cover on a plot.

The percent of ground cover proved useless, since
nearly all plots had 100 percent ground cover. The height
of the ground cover influenced the amount of jack pine
reproduction; the taller the ground cover, the lower the
percentage of plots stocked with jack pine (Table 14).
Varying ground cover components also affected jack pine
stocking (Table 15). Reindeer lichen had the highest per-
cent of plots stocked. Green moss and litter were also
significantly above the average. The reason for this is
that the competition by these ground cover components is
not great. Reindeer lichen lacks a root system so it is
not demanding on soil moisture. Also, when the reindeer
lichen is disturbed, it remains so for a relatively long
period. It is interesting to note that 62 percent of all
the plots with reindeer lichen were stocked with jack pine,
regardless of whether the lichen was of first, second, or
third importance on the plot. Plots dominated by slash,
blueberry, and bracken fern are below the average stocking
of 36 percent. Bracken fern in many instances forms a
dense cover and is over 3 feet tall. Blueberry also forms

dense cover, particularly in accumulations of slash. Slash

36

Table l4.--Effects of ground cover on jack pine stocking.

 

 

 

Height of Mil-Acres Mil-Acres StOcked
Ground Cover Sampled with Jack Pine
Inches Number Number Percent
6 73 41 56
6 to 18 1,679 698 42
Over 18 1,363 380 29

 

Table 15.4-Jack pine stocking with various ground cover
conditions.

 

 

 

Major Ground Mil-Acres Mil—ACres Stocked
Cover Component Sampled with Jack Pine
Number Percent

Reindeer Lichen 163 76

Green Mosses 33 55

Litter 178 47
Bearberry 128 43
Grasses 1,091 39
Sweetfern 86 37
Bracken Fern 355 32
Blueberry 757 28

Slash 288 16

Othera 36 22

 

aIncludes juneberry, willow, raspberry, and cherry.

37

on the plots was generally not light and scattered, but
accumulated in piles over 3 feet high.

The stocking of an area with jack pine reproduc-
tion increases with number of years after cutting (Figure
2). It takes several years to adequately stock a stand,
and stocking will continue to improve with time. It is
probably advisable to have 7 to 10 years between the seed
cut and the removal cut in a 2-cut shelterwood system.
However, if 3 cuts are used, perhaps 10 years would be
long enough between the preparatory cut and the removal
cut.

The Shelterwood Method and
Multiple-Use Management

 

For any forest reproduction method to be used
with success, it must be compatable with the management
objectives of the ownership. The owner or agency con-
cerned here is the Michigan Department of Natural Resources.
The management objectives for the State Forests call for

management for sustained multiple-use:

 

In state forest management all known uses are
carefully weighed and the combination of uses
believed to give the greatest benefit to the
largest number for the longest time are pursued
to the extent of funds and personnel available.
(12. p. 1)

The objectives also state that where possible, timber
management will be used as the principal tool to achieve

other multiple—use management objectives.

38

70'

60'

Percent

Mil~acres stocked -

 

 

5 1964 19 1959
Year when cut

Figure 2. Jack pine stocking by year of cutting.

39

Specifically, the Objective Of jack pine management
is to retain the jack pine type on soils suited to it,
and to manage stands in a manner that will produce optimum
quantities of jack pine timber compatable with maintenance
of desirable wildlife habitat.

The shelterwood method meets these objectives very
well. It can be used only where there is an adequate num-
ber of open-coned trees, but where there are enough Open-
coned trees, reproduction can be obtained at less cost
than either by planting or by scarification and clear-
cutting. Since the ground cover and understory vegetation
are likely to be more diversified with the shelterwood
method than with clearcutting, conditions for wildlife
will be more favorable. The resulting stand is likely to
be more patchy or irregular than a plantation, with more
edge effect for wildlife. Figure 3 illustrates the clumpy
nature of a mature jack pine stand and the reproduction 7
years after a shelterwood cut was made.

Michigan is very deeply concerned with and involved
in outdoor recreation. This means that as a public agency,
the Forestry Division of the Department of Natural Resources
must be concerned with the aesthetics of its forest lands.
In some instances, cutting practices will have to be modi-
fied if management programs are to not only be continued
but expanded. The shelterwood method goes hand—in-hand

with maintaining an aesthetically pleasing forest landscape.

40

 

 

 

Figure 3.--A mature jack pine stand showing the clumpy
nature of the residual stand and the repro-
duction 7 years after a shelterwood cutting
was made. The habitat is more diversified
than on clearcut areas or in a plantation,
and thus more favorable for wildlife. Stand
number 37 in Kalkaska County, stocked with
764 seedlings per acre.

41

The public sometimes reacts unfavorably to drastic changes
in the forest such as a clearcutting. Figures 4 and 5
illustrate some unfavorable aspects of a clearcutting in
jack pine.

The cuttings in the shelterwood method may go
practically unnoticed by the public, as the mature stand
disappears in stages, so that when the final cut is made,
the reproduction is already several feet high. If a 3-
cut shelterwood method is used, with 10 to 20 years be-
tween the preparatory and removal cuts, the reproduction
may be more than 5 feet tall when the residual stand is
removed. Figures 6 and 7 show stands that were cut using
the shelterwood method, which are ready for the removal
cut to be made.

Perhaps the shelterwood method does not result in
as much reproduction as quickly as would a clearcutting
with scarification and slash scattering or followed by
planting. However, there may be serious doubt whether
planting is advisable from an economic standpoint, and
perhaps scarification and slash scattering cannot be
justified economically either. In current practice on the
state forests, very little scarification and slash scat-
tering are being applied.

Like other silvicultural methods that might be
applied to mature jack pine stands, the shelterwood method

has some limitations. Often, there is inadequate seedbed

42

 

 

Figure 4.—-A jack pine area in Crawford County 2 years
after clearcutting. Very little reproduction
has become established since the cutting was
made. Heavy infestation by the jack pine
budworm (Choristoneura pinus Free.) necessitated
the clearcutting. The standing dead trees were
unmerchantable stems.

43

 

Figure 5.--The same stand as shown in Figure 4. Here an
attempt was made to screen the clearcut area
by retaining a buffer strip along the road.
Buffer strips in stands like this, with prac-
tically no understory vegetation, are not very
effective.

44

 

 

Figure 6.--A jack pine stand 9 years after being cut by
the shelterwood method. Stand number 41 in
Ogemaw County, with 1,657 jack pine seedlings
per acre. The removal cut could be made at
any time.

45

 

Figure 7.--Stand number 39 in Ogemaw County 5 years
after a shelterwood cutting, and now ready
for the removal cutting. This stand has
2,349 jack pine seedlings per acre. The
measuring stick in the photograph is 1
meter long.

46

preparation with conventional logging methods. Perhaps
this is not any less satisfactory than if the stand is
clearcut.

In areas where open-coned trees do not amount to
at least 8 square feet of basal area per acre, success is
not assured with this method because the seed source is
inadequate.

Two-storied stands result in problems with the
jack pine budworm. The insects fall off the overstory
and onto the reproduction, causing high mortality in many
instances. Many stands in this study would have shown
more success if there had not been so much seedling mor-
tality caused by the budworm. This was particularly the
case in Crawford and Oscoda Counties.

There is a tendency for some stands cut by the
shelterwood method to convert to low quality oak. If
these stands are to be maintained in jack pine, the oak
must be cut or treated with silvicides. This is probably
easier to accomplish in a clearcutting than in a shelter-
wood cutting.

It takes at least two cutting Operations to har-
vest the same material that one Operation would in a
clearcutting. It is possible that economic returns may
not be maximized by having two Operations instead Of one,
but state forestry personnel reported no difficulty in
marketing stumpage sales for the various shelterwood cuts

without apparent reduction in prices.

47

The losses due to mortality occurring between the
seed and harvest cut must be considered when this method
is used. This loss would not occur if the stand were
clearcut. In some stands, this loss was substantial,
amounting to as much as 15 square feet of basal area per
acre. The average loss for all stands was 3.8 square feet
per acre. With careful marking, mortality losses can be
reduced to a minimum. All trees that are not expected to
survive between cuttings should be removed in the seed

cut.

SUMMARY AND CONCLUSIONS

The Objective of this study was to evaluate the
shelterwood method as it is being used in jack pine
stands in the state forests in northern Lower Michigan,
and to make recommendations as to its continued use. To
accomplish this, 42 stands in Otsego, Kalkaska, Crawford,
Oscoda, and Ogemaw Counties were examined. Residual basal
area data were obtained from BAF 10 point samples taken
every 4 chains in each stand. Reproduction data and re-
lated information were obtained from 5 mil-acre plots
taken at each point sample location.

The average percent of mil-acre plots stocked
with jack pine was 36 percent, and there was an average
of 754 seedlings per acre. This indicates that the shel-
terwood method is suited to reproducing jack pine in the
study area and perhaps elsewhere if there are ample open-
coned trees in the stands.

Several stands are converting to low quality oak.
The most important factor associated with conversion to
oak is the amount of oak residual basal area left after
the seed cut is made in the stand. The oak should be re-
moved before or at the time of the seed out if the jack

pine type is to be maintained.

48

49

Three types of cutting specifications had been used
in the stands that were included in the study: marked to
cut, marked to leave, and a diameter limit. Reproduction
success was highest in the stands that were marked to be
cut because a greater residual basal area was left, which
included more basal area of Open-coned trees than in the
other cutting specifications.

When percent of plots stocked was related to the
residual basal area of jack pine, it was found that a
relatively high residual basal area was favorable to jack
pine seedling establishment. The percent of plots stocked
with jack pine less than a foot tall was greatest in
stands with 70 square feet of residual basal area per acre.
Seedling development, however, was favored by less residual
basal area. Percent of plots stocked with reproduction
over 3 feet tall was greatest in stands with 20 square
feet of basal area per acre. This indicates that perhaps
a 3-cut shelterwood may be more desirable than a 2-cut
procedure. The environment for seedling establishment
would be good following the preparatory cut. The estab-
lished seedlings would then respond to the partial release
following the seed cutting. Additional seedling establish-
ment will occur following the seed cut before the removal
cut is made.

In general, stocking will increase as the residual

basal area of open-coned trees is increased. Therefore,

50

every effort possible should be made to make the residual basal
area 100 percent Open-coned trees.
Ground cover had a significant effect on jack pine re-
production. The more competitive the gound cover, the lower
the stocking with jack pine seedlings. On sites where the
ground cover was primarily reindeer lichen, reproduction re-
sults were satisfactory. On sites where the ground cover was
mainly blueberry, bracken fern, or grass, scarification may be
desirable. Reproduction in accumulations of slash was sparse.
Jack pine stocking increases as time since the cutting
increases. This study indicates that 7 to 10 years following
cutting are needed to attain adequate stocking. The resulting
stands would still be considered even-aged. If the rotation
is 60 years, the regeneration period could be as long as 12 years.
The shelterwood method is well adapted to multiple use
management. Timber production is accomplished, and wildlife
habitat conditions are more desirable than with clearcut con-
ditions,since the more variable vegetational stages provide
food and cover not obtained with clearcutting. The ground
cover and understory vegetation are more diversified, and the
patchy irregular stand structure provides considerable,highly
desirable,edge effect for wildlife. The aesthetic considerations
are also favorable with the shelterwood method. The new stand is
already established and evident before the mature one is completely
removed, avoiding the "denuded" stage in clearcutting procedures.
This established advanced reproduction represents the highly

desirable aesthetic condition of looking more "natural."

51

Adequate and in some cases even better results
could probably be Obtained with a 3-cut shelterwood sys-
tem. The preparatory cut should be made when the stand
is between 40 and 45 years old, favoring the open-coned
trees where possible, leaving between 60 to 90 square
feet of basal area per acre.

About 5 years later, the seed out should be made,
leaving a residual basal area of 25 to 40 square feet per
acre, as much of it as possible in open coned trees. The
greater the stocking of reproduction at this time, the
lower the residual basal area may be. As much of this
residual basal area as possible should be of Open-coned
trees, at least 8 square feet. Between the ages of 55 and
60 years, the removal cut should be made.

These recommendations may have to be varied some-
what for each individual stand. Also, where stumpage
prices would be significantly reduced because the harvest
would be spread over 3 operations, the 2-cut shelterwood
method would be preferable. Mortality losses between cuts
should be checked closely to make certain the extended
harvest period does not result in significant wood volume
losses.

The shelterwood method with the basic seed and
removal cuts appears to be successful in regenerating
jack pine stands in the state forests in northern Lower

Michigan. It makes possible the realization of multiple-use

52

management objectives for state forest lands. Its success
could be improved by minor changes in application, with
the most important one being the leaving of as many Open-

coned trees as possible when the seed cut is made.

LITERATURE CITED

LITERATURE CITED

Ahlgren, Clifford E. 1959. "Some effects of fire on
forest reproduction in northeastern Minnesota."
Journal of Forestry, 57:194-200.

 

Barrett, John W. 1962. Re ional Silviculture of the
United States. The RonaIa Press Company, New York.

 

Beaufait, William R. 1960. "Influences of shade and
site treatment, including fire, on germination and
early survival of Pinus banksiana." Forestry
Division, Department of Conservation, State of
Michigan, Lansing, Michigan. 79pp.

 

Benzie, John W. 1968. "Regeneration of cutover jack
pine stands." United States Forest Service. North
Central Forest EXperiment Station, Resource Note
NC-49 O

Cameron, Hugh. 1953. "Melting point of the bonding
material in lodgepole pine and jack pine cones."
Canada Department of Resources and Development,
Forestry Branch, Forest Resource Division, Silvi-
culture Leaflet 86.

Candy, R. H. 1951. "Reproduction on cut-over and
burned-over land in Canada." Canada Department
of Resource and Development. Forestry Branch,
Forest Resource Division. Silviculture Resource
Note NO. 92.

Cayford, J. H., Z. Chrosciewics, and H. P. Sims. 1967.
"A review of silvicultural research in jack pine."
Canada Department of Forestry and Rural DevelOp-
ment. Forestry Branch Department Publication No.
1173.

Eyre, F. H. 1938. "Can jack pine be regenerated
without fire?" Journal of Forestry, 36:1067-1072.

 

Eyre, F. H. and R. K. Labaron. 1944. "Management of
jack pine stands in the Lake States." United
States Department of Agriculture. Technical Bul-
letin, No. 863.

53

10.

11.

12.

l3.

14.

15.

l6.

17.

18.

19.

54

Fraser, J. W. 1959. "The effect of sunlight on the
germination and early growth of jack pine and red
pine." Canada Department No. Aff. and National
Res., Forestry Branch, Forestry Research Division
Technical Note 71.

Matte, Francois. 1964. "A symposium: some aspects
of jack pine management." Pulp and Paper Maga-
zine of Canada. 65(4):WR l82-WR 189.

Michigan Department Of Natural Resources. "Timber
Management on Region II State Forests."

Row, Eugene I. 1963. "Seed stored in cones of some
jack pine stands, Northern Minnesota." Lake
States Forest Experiment Station, United States
Forest Service Research Paper LS-l.

Rudolph, T. D., R. E. Schoenike, and R. Schantz-
Hansen. 1959. "Results of one-parent progeny
tests relating to the inheritance of open and
closed cones in jack pine." School of Forestry,
University of Minnesota, St. Paul, Minnesota,
Minnesota Forestry Note No. 78.

Schoenike, R. E., T. D. Rudolph, and T. Schantz-
Hansen. 1959. "Cone characteristics in a jack
pine seed source plantation." School of Forestry,
University of Minnesota, St. Paul, Minnesota,
Minnesota Forestry Note No. 76.

Society of American Foresters. Lower Michigan
Chapter. 1959. "Recommended forest cutting
practices for Lower Michigan." 37pp.

United States Department of Agriculture. 1965. Sil-
yics of Forest Trees of the United States. UnIEEd
States GovernmenEIPrInting Office. Agriculture
Handbook No. 271.

 

 

Veatch, J. O. 1941. "Agricultural land classifica-
tion and land types of Michigan." Michigan State
College, Agricultural Experiment Station. Special
Bulletin 231.

Watson, R. J. 1937. "Jack pine in Michigan." United
States Department of Agriculture, Forest Service,
Region 9. (Mimeo)

APPENDIX

APPENDIX I

SCIENTIFIC NAMES OF SPECIES ENCOUNTERED

IN THIS STUDY

A. Tree Speciesl

 

 

 

 

 

 

 

 

 

 

l. Aspen - Po ulus tremuloides and.
POEUIUS grandidentata Michx.

2. Balsam fir - Abies balsamea (L.) Mill.

3. Beech - Fagus grandifolia Ehrh.

4. Jack pine - Pinus banksiana Lamb.

5. Red maple - Aggr rubrum L.

6. Red oak - Quercus rubra Michx., and
OEEEEES EIIIEsoidalis E. J. Hill

7. Red pine - Pinus resinosa Ait.

8. Spruce — Picea mariana (Mill.) B.S.P. and
Picea §I3533_(Moench) Voss

9. White oak - Quercus alga L.‘

10. White pine - Pinus strobus L.

 

B. Ground Cover Species2

 

 

 

 

 

 

 

 

 

l. Bearberry - Arctostaphyles uva-ursi L.

2. Blueberry - Vaccinium spp.

3. Bracken fern - Pteridium aquilinum (L.) Kuhn
4. Cherry - Prunus spp.

5. Grasses - Danthonia spicata (L.) Beauv.

and other xerOphytic grasses.

6. Green mosses - Polytrichum spp.

7. Raspberry - Rubus idaeus L.

8. Reindeer lichen - Cladonia spp.

9. Serviceberry - Amelanchier spp.
10. Sweetfern 4 Comptonia peregrina (L.) Coult.
11. Willow - Salix spp.

1

Little, Elbert L., Jr. 1953. Check list of Native
and Naturalized Trees of the United States. Forest SerVice,
U.S. Department of Agriculture, Agriculture Handbook No. 41.

 

 

2Fernald, Merritt L. 1950. Gray's Manual of Botany.
American Book Company, New York, New York.

55

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