NUTRITIONAL-ECOLOGim ammusaws
AFFECI‘ING HEEGHT Gmwm OF PLANTED
VEELOW-POPLAR mammmou warm“ L)
m somuwzsmm mm

Msfuthobogmoiphb.
MICHIGAN STATE UNIVERSITY
"Charles Edward Schomakor
1962

This is to certify that the

thesis entitled

NUTRITIONAL~ECOLOGICAL RELATIONSHIPS
AFFECTING HEIGHT GRO’NTH OF PLANTED
YELLON—POPLAR (LIRIODENDRON TULIPIFEIRA
L.) IN SOUTHNESI‘ERN MICHIGAN

presented by
Charles Edward Schomaker

has been accepted towards fulfillment
of the requirements for

Ph. D'degreein Forestry

aw

Major professor

0.169

 

 

ABSTRACT

NUTRITIONAL-ECOLOGICAL RELATIONSHIPS AFFECTING
HEIGHT GROWTH OF PLANTED IEme-POPLAR (L‘IRIODENDRON
TULIPIFERA L.) IN SOUTHWESTERN MICHIGAN

{s

by Charles E:“Schomaker

Two parts of a yellow-poplar (Liriodendrcn tulipifera
L.) plantation in the Fred Russ Forest in southwestern

Michigan, show a striking difference in height and diameter

growth. TWenty-two years after planting, trees in the better

area are approximately double the size of the trees in the
poorer area. .Since yellow-poplar is a highly desirable
hardwood species for reforestation, a study was made to
determine the reasons for this growth differential.

The plantation is located on an abandoned agricultural
field with similiar topography and soils throughout.. There
is no evidence of variation in past 1and~use practices
between the two growth areas. The better growing trees are
within an area influenced by an old-growth stand of mixed
hardwoods which lies immediately to the south and west of
the plantation. .

In 1951 and 1952, R. D. Shipman made~a microclimatic
and edaphic study of the plantation. His study showed that
there are significant microclimatic differences between the
two areas, but he did not report any important soil nutrient

differences between the areas of good and poor growth. He

concluded that the growth differences between the two growth

areas are the result of microclimatic variation that produced
a more favorable soil moisture regime in the area of good
growth.

The foliage and general appearance of the trees in the
poor growth area suggest nutrient deficiencies not evident
in the good growth area. Besides the size difference, the
poorer trees have smaller leaves that show chlorosis and
bronzing, suggestive of nitrogen and phosphorus deficiency.
In contrast, the leaves of the better trees are larger and
exhibit a healthy green color. In addition, the leaves of
the poor growth trees turn to autumn colors and abscise
several weeks earlier in the fall than the good growth trees.
This is also an indication of nitrogen deficiency. Following
these observations, the nutrient regime of both areas was
examined, using both foliar analysis and a chemical soil
examination.

A statistical comparison of the foliar analysis data
revealed that there are significantly greater concentrations
of nitrogen and phosphorus in the leaves from the good growth
area as compared with the poor growth area. Comparing these
results with other studies strongly indicate that a severe
nitrogen and phosphorus deficiency exists in the poor growth
area but not in the good growth area. This conclusion is
strengthened by the highly statistically significant cor-
relation between both tree height and diameter, and the.
concentration of both nitrogen and phosphorus in the leaves.

The chemical soil analysis did not show statistical

difference for any of the factors tested in the A horizon.
In the B horizon, however, the concentrations of total
nitrogen and available phosphorus were highly significantly
different between areas. The nitrogen difference was in
favor of the poor growth area and the phosphorus difference
in favor of the good growth area. Other investigators have
shown that soil analysis is an unreliable means of deter-
mining the amount of nitrogen available to plants. There
has been little correlation between total nitrogen as
determined by soil tests and the growth of trees or other‘
plants. On the other hand, phosphorus content as determined
by soil tests has been found to be positively correlated
with tree growth.

The results of the foliar analysis indicate that the
good growth area has a more favorable soil nutrient regime
than the poor growth area. To find the source of the
additional nutrients in the better growth area, the annual
deposit of litter in both areas was examined. Over two and
one-half times as much litter was deposited on the good
growth area as the poor growth area, also the litter on the
good growth growth area was richer in many of the essential
nutrients. A sizeable portion of the additional litter comes
from the adjoining old—growth hardwood stand. '

It is concluded from the present study that the growth
differential between the two portions of the plantation is
due largely to more nutrients being available to the trees
in the good growth area as a result of the larger annual

deposits of litter. The poor growth area is severely

deficient in available nitrogen and phosphorus, and this

_ has limited the growth and vigor of the trees on that area.
In addition, the microclimatic differences found by Shipman
result in a more favorable transpiration-water absorption

ratio in the good growth area.

NUTRITIONAL-ECOLOGICAL RELATIONSHIPS AFFECTING
HEIGHT’GROWTH OF PLANTED'YELlOw-POPIAR (LIRIODENDRON
TULIPIFERA' L.) IN SOUTHWESTERN MICHIGAN

By
\34‘5

Charles EQJSchomaker

A THESIS

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

DOCTOR OF PHILOSOPHY
Department of Forestry

1962

ACKNOWLEDGEMENTS"

The author expresses his sincere gratitude to the many
persons who aided him in various ways in this study. These
include Dr. Terrill D. Stevens, Head of the Department of
Forestry, Michigan State University, and Drs. Donald P.
White and Jonathan W. Wright, faculty members of that depart-
ment. Also included are Hr. Raymond F. Finn, Project Leader,
Central States Forest Experiment Station; Dr. Henry D. Foth
and Mr. A. 8. Islam, Professor and Graduate Student respec-
tively, of the Department of Soil Science, Michigan State
University; and to Mr. S. w. McCullough, former Resident
Forester of the Fred Russ Forest, Cass County, Michigan.

Particular thanks are due to the author‘s faculty
advisor, Dr. Victor J. Rudolph, Associate Professor of the
Department of Forestry, Michigan State University, for
suggesting this study and for giving generously of his time
whenever help was needed. Dr. Rudolphls constant encourage-
'ment and advice is deeply appreciated.

To these and to all others who have not been mentioned,

my thanks are gratefully acknowledged.

ii

CHAPTER
I.
II.
III.
IV.

VI.

VII.

VIII.
IX.

TABLE OF CONTENTS

Introduction . . . . . . . .

Statement and Scope of the Problem . . . . .

Review of Literature . . . .
Description of the Study Area
Previous Experimental Work on
.Hethods and Procedure . . .
Foliar analysis . . ._. .
Litter analysis . . . . .
Soil sampling and analysis
Statistical analysis . . .
Results and Discussion . . .
Leaf analysis ... . . . .
Litter analysis . . . . .
Chemical soil analysis . .
Conclusions . . . . . . . .

Summary . . . . . . . . . .

LITERATURE CITED . . . . . . . . . .

APPENDIX

iii

TABLE

1.

6.

LIST OF TABLES

NitrOgen, phosphorus, and potassium concenp
trations reported for yellow-poplar foliage
by DPOVIOUS investigators e e e e e e e e e

Analysis of differences in height, diameter,
and leaf nutrient levels of yellow-poplar
trees in southwestern Michigan . . . . . . .

CorrelatiOn coefficients between height and
diameter of yellow-poplar and the level of
leaf nutrient concentrations . . . . . . . .

Quantity and nutrient compositon of litter
on two parts of a yellow-poplar plantation
in southwestern Michigan . . . . . . . . . .

Nutrient composition of the litter from two
parts of a yellow-poplar plantation in
southwestern Michigan . . . . . . . . . . . .

Analysis of chemical soil differences between

two areas of a yellow-poplar plantation in
southwestern Michigan . . . . . . . . . . . .

iv.

PAGE
15
49
50
58
6T

64

FIGURE
1.

2.

A.

7.

8.

9.

10.

LIST OF ILLUSTRATIONS

Map of the yellow-poplar plantation showing
the study area and surrounding lands . . . .

Soil map of the study area, located in a
yellow-poplar plantation, compartment F,
Fred Russ Forest, Cass County, Michigan . . .

Part of the old-growth, mixed hardwood stand
that lies to the south and west of the study
area. This stand adds considerable deposits
of litter each year to the good growth area .

Winter aspect of the southern edge of the good

growth area showing the excellent form of the -

yellow-poplar trees, typical of that area. . .

Winter aspect of a typical portion of the poor
growth area showing the relatively small size
and poor form of the yellow-poplar trees . . .

An oblique view through the study area showing
the decreasing total heights of the yellow-
poplars, from the good growth area in the
foreground to the poor growth area in the

baa keround C C O O O O 0 O O O O O O O O O O 0

Linear regression of percent concentration of
nitrogen in the leaves over the total height
of plantation grown yellow-poplar

(LiriOdendron tulipifera L.) . . . . . . . . .

Linear regression of percent concentration of
phosphorus in the leaves over the total height
of plantation grown yellow-poplar

(Liriodendron tulipifera L.) . . . . . . . . .

Considerable organic material from the preced-
ing year still remains on the ground surface
of the good growth area by late summer. This
material adds to the nutrient regime of that
aruaaChyeareeeeeeeeeeeeeeee

The soil surface of the poor growth area shows
a dense cover of grasses and herbs with very
little organic debris from the tree cover . .

PAGE

27

29

31

32

33

3b

56

57

69

APPENDIX
A.

LIST OF APPENDICES

Study Area Soil Descriptions . . . . . . .
Fox sandy loam (acid variant) . . . . .
Warsaw sandy loam (acid variant . . . .

Leaf and Litter Analysis Procedures . . .
Microkjeldahl procedure . . . . . . . .
Flame photometer procedure . . . . . . .
Photoelectric spectrometer procedure '.°.

Coefficients of Correlation of Combinations

of Tree Height, Tree Diameter, and Nutrient.

Element Composition of Leaves . . . . . .

vi

PAGE

92
92
93

95

CHAPTER I
INTRODUCTION

Growth is the foundation upon which good timber manage-
ment is built. The most profitable return from investments
in forest land for timber production is realized by growing
trees to merchantable size in the shortest possible time.
Matthews (1935) states that, "the whole aim in forest man-
agement is to get the greatest possible growth from our
forest and at the same time leave the smallest amount of
timber on the ground as a permanent capital investment.” To‘
.accomplish this objective, the forest manager must have
basic knowledge of the commercial tree-species best suited
‘for each site condition he encounters, and information on
practical means of improving site to promote faster growth
of quality trees. More information is needed in regard to
the soil, water, nutrient, and microclimatic requirements
of important tree species.

Tree growth is a result of all the combined influences
of environment acting on the genetic characteristics of in-
dividual'trees. The comparative growth rate will vary with
the balance of the environmental factors to the optimum
demanded by the inherited physiolOgical capabilities of each
tree.

This study covers certain phases of the environment as
related to the growth-variation of yellow-poplar (Liriodendron
‘ tulipifera L.) in two portions of a plantation established

in 1938. This twenty-acre plantation, located on former

1

2
agricultural land, is unusual because of the extreme differ-
ential height and diameter growth exhibited by trees planted
at the same spacing in a relatively restricted area. An
investigation to determine the reason for this difference in
growth is the object of this study. Since these trees came
randomly from the same nursery stock, the effect of genetic
variation on growth does not enter into the average differ-
ence between the two portions of the plantation studied, and
is not within the scOpe of this study. Hence, differences
in form, vigor, and especially size of these trees most likely
result from variations in the environmental complex between
the sites on which they are found.

Although it is practicable to investigate only separate
phases of the environment, it should be recognized that any
one factor does not affect tree growth as a single entity in
itself but only as a part of a vast interrelated and inter-
acting complex of factors. Temperature affects water availa-
bility and use. Soil moisture influences nutrient element
absorption, and soil nutrients may in turn affect the absorp-
tion of water. The interaction of the many factors may be
almost infinite and in many cases are unknown or unreCOgnized.
With this in mind, the present study is confined to a few
more obvious factors that may be seriously limiting.

Yellow-poplar (tulip-tree) is an important timber species
and more information is needed concerning its silvical
characteristics and the site conditions best suited for its
best growth. On the basis of its individual merits, this

tree can be considered one of the more valuable hardwoods in

3
the United States (Harlow and Harrar,194l; Smith, 1961). It
is relatively free from attacks of insects and-disease path-
ogens, and under forest conditions develops a tall, straight
trunk, free.of side branches for a considerable distance from
the ground. on good sites, growth is relatively rapid and
trees will attain heights of well over 100 feet (198 feet,
maximum recorded) and diameters up to 12 feet.

Yellow-poplar grows best on moist, friable soils of
moderate depth, where drainage is good. Although it will do
well on a wide variety of soils, it is not usually found on
either relatively wet or dry sites. Fertility appears to be
an important factor in the growth of this tree, and Mitchell
and Chandler (1939) classify yellow-poplar as a ”nitrOgen-
demanding” species. The root system is normally deep and
widespreading, and its crown is often small, oblong, and
rather open under forest conditions.

Yellow-poplar is intolerant of overhead shade, and is
normally not abundant in old stands. Large crops of seeds
are produced at irregular intervals, but germination is
usually low, averaging about 5 percent and rarely over 14
percent (U. 8. Forest Service, 1949). It usually seeds in
open fields or large clearings when the mineral soil has
been exposed. Because of its many desirable qualities,
yellow-poplar is widely planted throughout its range.

The wood of this species is moderately soft and weak,
straight-grained, light, and even-textured. It is easily
worked without tendency to split, and is well suited to

rotary cut veneer used for the interior finish of furniture

4
and cabinet work. The sapwood is whitiSh in color and the

heart-wood yellOw to pinkish-brown. The wood has a wide
variety of uses, the most important being for furniture,

doors, sashes, and musical instruments (Brown and Panshin,
1940) .

CHAPTER II
STATEMENT AND SCOPE OF THE PROBLEM

The problem of site requirements for planting commer-
cially valuable forest trees is an extremely important one.
Large expenditures of time and money have been wasted by
planting species on sites for which they were not adapted.
Such attempts result in either low survival, or equally
important, in such low growth rates and poor form that the
land itself can usually be considered wasted. However, once
the site requirements are well known for all important species,
each site can be fully evaluated and the best species for
those conditions can be planted. As is often the case, areas
in need of planting can be reclaimed, at least to some extent,
by a program of site improvement through the Judicious use
of fertilizers, weed control, deep plowing, cover crops, or
other means of site preparation.

YollOw-poplar is a favored species for hardwood planting.
The value of this highly desirable tree is limited only by
its relative scarcity in natural stands. Attempts to plant
yellow-poplar sometimes meet with failure because of its
rather exacting site requirements. Even areas which once
were good natural yellow-poplar sites may not be adaptable
fer planting because of deterioration from past poor land
practices or through changes in microclimate. On one such
area in Cass County, Michigan, yellow-poplar was planted in
a field abandoned for agricultural use. There, the success

of the planting over most of the area was spectacularly poor,

5

6

not through lack of establishment, but because site conditions
resulted in poor growth and form of the trees. Near the
southern and part of the western boundary of the plantation,
however, an exception to the generally poor condition of the
trees-is found. There, the yellow-poplar has made acceptable
growth, and exhibits the tall, straight, clean form that
makes it such a desirable tree.

The difference between the areas of good and poor growth
was outstanding from the early years of the planting.
Shipman (1952) studied soil and microclimatic conditions in
both parts of the stand. Data from the study failed to
reveal any important soil differences. SOme significant
microclimatic variations were observed between the two areas,
but not of a magnitude to accOunt fully for the large apparent
site variation.

The persistent, striking difference in the appearance
of the trees in the two portions of the stand with respect
to color, leaf size, and density of the foliage coupled with
obvious differences in tree size and vigor strongly suggest
site variation related to soil fertility. In addition,
history of past agricultural practices on this area indicates
that the soil was badly depleted of nutrient elements.

This study evaluates soil fertility factors by using
foliar analysis to measure the nutrient availability in the
two parts of the plantation. A more precise resampling and

analysis of the soil using advanced methods is also included.

CHAPTER III
REVIEW OF LITERATURE

The relationships between environment and tree growth
have long been an important consideration in management of
forest land. In forestry, these considerations are expressed
by the concept of site, and the study of site factors and
their measurement has occupied the attention of many inves-
tigators.

Site is defined by the society of American Foresters
(1958) as ”an area, considered as to its ecological factors
with reference to capacity to produce forests or other
vegetation; the combination of biotic, climatic, and soil
conditions of an area." It might also be expressed as a
specific (but dynamic) combination of many interrelated
biotic, climatic, and edaphic factors found on a particular
area, which in their total effect, regulate the growth of
trees (or other vegetation) within the boundaries of the
plant'b genetic capabilities. This combination of factors,
acting together, regulate the supply and distribution of the
basic necessities for vegetative growth; space, moisture,
light, a desirable temperature range, oxygen, carbon dioxide,
and the essential plant nutrients (Kramer and Kozlowski,
1960).

Heiberg and White (1956) point out that site is a
complex composed of many factors influencing the develop-
ment of a forest, and that a forester must be aware of all

the effective factors that contribute to this development.

7

8

They say, further, that it is especially important that the
forester sift out the most important factors that dominate
growth, health, or form of the vegetation on a particular
site. Husch (1959) observes that the relationship of growth
to environment is difficult to measure. (The factors of site
and the plants themselves are interacting and interdependent,
making it difficult to assign cause and effect relationships.
Like Heiberg and White (1956), he emphasizes.that one faster
must not be isolated and studied alone, lest the influence
of other factors be masked and consequently not recognized.

Although it is important to recognize that all site
factors affect growth, certain of them frequently dominate
the productivity of an area (Heiberg and White, 1956; Kramer
and Kozlowski, 1960). Once these dominant site factors have
been determined, the forest manager is better able to plan
his operation. Some feetors such as macroclimate, physioge
raphy, and certain soil conditions cannot be eaSily manip-
ulated, and species or fOrest types must be sought that are
best adapted to these confines. Others can be altered by
Judicious use of silvicultural and site imprOVement tech-
niques to provide better tree growth (Kramer and Kozlowski,
1960; Rudolph, 1958). i '

In nature, growth of trees probably never reaches its
genetic potential. One or more of the basic necessities are,
usually limiting to some extent. The principle of limiting
factors was first proposed by Liebig in 1843 in his ”law of
the minimum", and was later modified by Blackman and by;
Mitscherlich (Kramer and Kozlowski, 1960; Meyer and Anderson,

1952).

Blackman's application of Liebig's "law of the minimum"
was subject to some question, and in 1909 Mitscherlich '
modified this concept to state that "the increase in any
crop produced by a unit increment of a deficient factor is
proportioned to the decrement of that factor from the maxi-
mud'(Bray, 1954). This interpretion of the principle of
limiting factors is probably more in accord with actual
conditions.

Available water is frequently the factor most limiting
(to tree growth on most forest land. White (1958a) states
that "taking the temperate forest regions as a whole, the
supply of water from all sources available for plant growth
is usually less than optimum and therefore limiting.”
Kozlowski (1958) reports-that soil moisture deficits often
occur at the time of year when other factors are often the
most favorable for growth and that water undoubtedly controls
growth more than any other factor in many areas.

Working in the south, Zahner (1956) found that a water
deficiency occurred as early as May in some years, on sites
with limited storage capacity. In most years, water deficits
that limited growth had occurred by June on nearly every
site evaluated. In New Hampshire, Husch (1959), working
with four different site conditions, found that cessation
of growth of white pine could be attributed to an interaction
between photoperiod and soil moisture.

A study in North Alabama (Schomaker, 1958) found that

early survival of planted yellow-poplar decreased with

10
decreasing soil moisture, and that there was a strong posi-
tive correlation between height growth and percentage of
soil moisture for the first two years after planting.
Available moisture holding capacity of the soil was found to
be highly and positively correlated with Jack pine growth
(Pawlick and Arneman, 1961). White (1958a) points out that
”most workable (site) classification schemes are, in effect,
an attempt to estimate indirectly the soil moisture regimes
and specifically, 'available water' for tree growth."
"Except in situations of acute nutrient shortage, a scheme
which would estimate the amount and distribution of available
water during the growing season would most probably most
accurately evaluate site."

The importance of available water as the most limiting
factor on many sites has often led foresters into the error
that other factors are not important. On the other hand,
Wilde (1958b) emphasizes that in spite of the far-reaching
influence of soil moisture, it cannot be singled out as the
most important ecological factor as is so often expressed
in forest literature, but that the development of any plant
depends upon the satisfactory level of all soil factors.

Plant nutrients have been receiving increasing attention
as an important site factor. These essential elements for
plant growth, long ignored or depreciated by many American
foresters, are now coming into their own. Wilde (1958b)
notes that early students of environment were inclined to
overemphasize the role of water in plant growth and pay
little attention to nutrients. Voigt (1958) states, "while

11
no one can deny the sometimes paramount importance of soil
moisture in tree growth, it should be appreciated that the
level of available nutrient elements also exert a very posi-
tive influence." On old fields, depleted of soil nutrient
elements from years of destructive agriCulture, and on un-
cultivated but naturally infertile soils, deficient nutrients
may be a more seriously limiting factor than soil moisture.
Even when soil moisture has been seriously deficient, Judi-
cial applications of nutrient elements have resulted in
increased yields and a better utilization of water for growth
(White, 1958a).

Many foresters formerly believed that all forest sites
had a sufficient supply of nutrients for tree-growth, and
that plant nutrients are not as important for forest trees
as they are for agricultural crops. Certain fundamental
differences do exist between nutrient utilization by forest
and farm crops, but an adequate supply of nutrients is as
essential for one as for the other. Deeply penetrating and
widespreading root systems enable forest trees to more
efficiently exploit less fertile soils for nutrients. In
addition, annual removal of large volumes of plant materials
in agriculture has a greater tendency to deplete the soil
of nutrients than routine forest practices.

Mitchell and Finn (1935) state that the net loss of
plant food elements from forest soils is almost negligible,
even though a timber crop is harvested periodically. Cycling
of plant nutrients through deep root feeding by trees, and

annual leaf fall, maintain the fertility Of a forest site

12
(Mitchell and Finn, 1935; Wilde, 1958b). In addition, the
litter cover on the forest floor, plus the lack of annual
cultivation provide a more favorable habitat for soil micro-
organisms, which in turn results in a more rapid release of
nutrient elements from soil minerals and organic matter.
Mycorrhizal associations of tree roots also are a factor in
the better utilization of relatively infertile sites.

The importance to soil fertility of annual additions
of organic matter and of the plant nutrients it contains,
is well established. Ovington (1956) states that a well
stocked forest stand produces approximately 3,000 pounds
of dry leaf matter per acre. ScOtt (1955) reported that a
mixed hardwood stand in the Appalachians produced an esti-
mated 4,000 pounds of litter per acre per year, a 50 year-
old birch stand produced 2,970 pounds, and the hardwood type
in general produced an average annual quantity of 1,842
pounds of litter per acre. A hardwood stand producing 1,572
pounds of litter per acre provides 11.9 pounds of nitrogen,
7.7 pounds of potassium, 2.3 pounds of phosphorus, 12.5
pounds of calcium, and 6.4 pounds of magnesium per acre.
Yellow-poplar litter was reported to contain 0.51 percent
nitrogen, 0.11 percent phosphorus, 0.956 percent potassium,
0.21 percent magnesium, and 2.56 percent calcium.

Despite the ability of forest trees to occupy infertile
sites more efficiently than agricultural crops, tree nutrients
may be seriously limiting on some areas and should not be
ignored. Carried to the extreme, a marked deficiency may

occur, resulting in low-vigor, slow growing trees showing

13 .

obvious deficiency symptoms. Even where no clear visual
deficiency symptoms are exhibited, trees may have "hidden
hunger" resulting in a significant depression of growth over
what is possible if soil nutrients were at an optimum level.
Leyton (1957b) states that substantial increases in tree
growth have been reported in many countries following appli-
cations of mineral fertilizers, and it is_generally recognized
that many soils under forest cover or available for reforest-
ation are deficient in nutrient elements. In his own work
in England (Layton, 1956), he found a marked response in the
growth of sitka spruce when the nutrient status of the trees
was improved by fertilization. ’

Fertilization of yellow-pOplar seedlings on a low-nutri-
ent site resulted in a significant increase of height growth
the first year after planting as compared to trees without
fertilization (McAlpine, 1959).

'Many examples of increased growth resulting from improved
soil fertility due to fertilization are cited by White and
Leaf (1956). Stone (1958) reports that foliar tests from 70
localities plus similar results from other work, indicate
that inadequate nitrogen limits growth in many northeastern
forests. Substantial increases in height and diameter growth
and in the nitrogen content of the leaves of yellow-poplar
and other species were found, when planted in a mixture with
the nitrogen-fixing legume, black locust, over that of the
same species planted on the same site in pure stands or in
mixtures with non-legumes (Finn, 1953a).

Swan (1960) believes that growth in many Canadian nurs-

14

eries, plantations, and natural stands is being seriously
retarded by nutrient deficiencies. The importance of soil
fertility is wellrecognized in Australia (Moulds and Apple-
quist. 1957), where it is standard practice to analyze the
soil for total phosphate prior to plantation establishment.
Deficient areas are brought up to an established minimum
level by additions of superephosphate. Corrections for zinc
deficiencies are also necessary in certain instances in
Australia (Kessell and Stoate, 1938). Thus it becomes
increasingly clear that attention should be given to the
nutrient regime of forest sites.

An early and thorOugh study of the nitrOgen nutrition
of deciduous trees by Mitchell and Chandler (1939) showed
that the range from 2.15 to about 3.00 percent of dry leaf
weight of nitrogen is needed for optimum growth of yellow-
poplar. Leaf analysis of yellow-poplar growing naturally
on a variety of sites in northeastern United States had
nitrogen concentrations of from 1.70 to 2.33 percent of dry
leaf weight (Table 1), with an average of 2.04 percent.
Applications of fertilizer using 60 pounds, 120 pounds, and
180 pounds of nitrOgen per acre on the poorest site (1.70
percent leaf nitrogen) resulted in annual diameter increments
of .166 inches, .258 inches, and .280 inches, respectively,
as compared to .119 inches on the control plot (no fertilizer).
In the southeast, Wells (1961) states that leaf concentrations
of 1.08 percent nitrogen is considered deficient for yellow-
poplar.

On nine sites where Mitchell and Chandler (1939) analyzed

15

Table 1. - Nitrogen, phosphorus, and potassium concentrations
reported for yel ow-poplar foliage by previous investigators

 

Tree ' nutrient concentration . .
classification N‘ P K Investigator(s)

 

percent dry leaf weight'

1.93 0.21 1.46
2.07 0.31 1.61
2 .33 O ols 1 033

2.22 0.19 1.55 Mitchell and

Natural mature 1.70 0.14 -
. 2.28 0.28 _ Chandler (1939)
2.06 0.15 -
1.82 0.20‘

1.93 0.26 2.05

 

1.85 - -
Planted immature, 2.54 - -
old-field site i-ii ' - Finn (1953a)

2.32

 

Planted, mature 1.50 0.30 1.30 Bard (1946)

 

Planted, immature, 1°54 0°11 0'51 White and

 

infertile old- i‘;$ g'%; 8‘2; Finn (1961)1/
field site 1.52 0.12 0.68 unpublished data
Planted, immature,

infertile old- 2-29 0-15 0-24 ‘White and Finnl/V
field, fertilized 2-37 0°17 0’ 9 (1961)

_ - 2.00 0.24 0.45
w We“ m

 

the leaves of deciduous trees for nutrient elements, yellow-
poplar leaf tissue had phosphorus concentrations from 0.14
to 0.31 percent of dry leaf weight with an average of 0.21
percent (Table 1). Potassium analyses were reported on five

. an nn 1961. Unpublished data.
Dept. of Forestry, Mich. State Uhiv.

16
of these sites, and levels ranged from 1.33 to 2.05 percent
of dry leaf weight, with an average of 1.60 percent.

In addition to the work of Mitchell and Chandler (1939),
table 1 presents results on nutrient concentration of yellow-
poplar leaves obtained by Bard (1946), Finn (1953a), and
unpublished data supplied by White and Firm (1961) M

In a study relating mineral composition of white oak
leaves to site quality, Finn (1953b) found nitrOgen contents
ranging from 1.62 to 2.57 percent of dry leaf weight, with
an average of 1.92 percent. Site index was found to be
correlated with nitrogen concentration. Potassium concen-
trations averaged 1.42 percent dry leaf weight and ranged
from 1.01 to 1.76 percent. Leaf concentration of phosphorus
varied from 0.12 to 0.27 percent and averaged 0.17 percent
of dry leaf weight. In that study, neither potassium or
phosphorus content was found to be related to site qualtity.

Walker (1953) reported potassium concentration in the
leaves from the middle of the crown of various tree species
in connection with the exchangeable potassium content of
glacial outwash soil in New‘York State. Potassium concen-
trations of leaves collected in August, averaged 0.74 percent
for American beech, 0.67 percent for red maple, 1.26 percent
for black cherry, and 1.08 perCent for gray birch. Leaves
from these trees showed no visible deficiency symptoms.
leaves from black cherry, red maple, and gray birch showing
potassium-deficiency averaged 0.55, 0.50, and 0.71 percent

potassium respectively.

 

l/‘White, D. P.,and R. r. Finn 1961. op. cit.

17'
Leaves of unfertilized, healthy pin oak trees collected
' on the Ohio State University campus had average phosphorus
concentrations of 0.126 percent and potassium concentrations
of 0.92 percent of dry leaf weight (Cannon e1 a1., 1960).
Chapman (1960) lists values of 0.50 to 1.00 percent potassium
and 0.12 percent phosphorus on a dry leaf basis to be consis-
tent with the top performance of citrus orchards in Cali-
fornia.

The deficiency of any one of the fifteen essential
nutrient elements will result in reduced or abnormal growth,
or in the death of the tree as a result of the interference
with its normal physiological processes (Kramer and Kozlowski,
1960). Deficiency symptoms-of the essential nutrients and
the functions of these nutrients in the metabolism of the
tree are described in such texts as Kramer and Kozlowski's
Physiology 2; Taggg (1960) or Wilde's Forest S2113 (1958b).

Unfavorable nutrient regimes on forest sites are often
difficult to detect and are sometimes masked by other limit-
ing factors, especially soil moisture. Where a nutrient
deficiency is suspected without easily visible symptoms,
two methods of nutrient analysis may be employed; soil
testing, and tissue analysis of existing vegetation.

Soil testing is widely used in agriculture as a means
of estimating fertilizer needs. Because of the value and
general aCcoptance of this technique in agriculture, attempts
have been made to use or at least adapt this method for
forest lands. These attempts have met with varied but often
limited success and have fostered the belief that soil

18
fertility is relatively unimportant in forest practices.-

The lack of success of soil testing in determining the
true available nutrient levels on forest sites is due both
to certain inherent differences between forest and agricul-
tural crepe, and to certain weaknesses in the method itself.
Even in agriculture, soil testing is being more and more
regarded as only a general method for assessing fertilizer
needs rather than an exact means for determining the nutrient
regime of an area.

Hoagland (1949) states that soil analysis cannot be
relied on (except for unusual cases) to tell a farmer the
best fertilizer for his soil condition. It is especially
peer for evaluating nitrogen. Goodall and Gregory (1947)
say that, "the pregress made with chemical soil analysis ...
has net led agricultural chemists to become less aware that
attempts to imitate the action of plant roots by chemical
extractants can never hope to meet with full Success, and
. that workable approximations are the most that can be expected."
'Develepments in soil testing have evolved determinations
for phosphorus and potassium which give results in tolerable
agreement with field trials. However, methods for deter-
mining "available" nitrogen in the soil have never met with
general acceptance, due to its transient nature in the soil.

In forestry, soil testing seems to have less application
than in agriculture, at least at the precent level of know-
ledge. Gessel and Walker (1958) believe that soil testing
is beset with many difficulties, and that foresters are not

in a position to correctly diagnose forest nutrient needs on

19
the basis of a simple soil test. They support this view by
pointing out that soil tests do not show how trees absorb
and utilize nutrients according to the basic nutrient re-‘
quirements of each species. That differences in the avail-
ability (or feeding power) of nutrients do exist between
species is shown by Mitchell and Finn (1935). They found.
that red maple accumulated approximately twice the amount
of phosphorus in its leaves as did red oak when growing on
the same site with the same fertiliZor treatment.

Gessel and Walker (1958) state that the type and method
of soil testing used by agriculture is not applicable in
‘the Same manner to forest crops, and that field tests are
needed in conjunction with available testing methods. The
use of foliar analysis as the best means of evaluating
forest nutrient needs is advocated. This view is shared by
Leyton and Armson (1955) who state that soil analysis has
not preved as reliable in the assessment of site fertility
for forest trees as for agricultural crops.

York (1958), an agronomist, observes that while soil
' analysis can serve a useful purpose in forestry, its appli-
,cation will undoubtedly be more limited than in agriculture
due to difficulties in sampling and correlation. Voigt (1958)
makes the point that the methods for chemical soil analysis
were developed for agricultural crops, and the nutrients
extracted by the reagents in current use may bear little
relationship to the true situation in forest soils. Mitchell
(1935) believes that the ordinary methods of direct chemical

soil analysis are not completely satisfactory because no

2O

distinction is made between available and non-available
nutrients. Certain of the so—called extractive methods in
which "available“ nutrients are leached from the soil with
various solvents are preferable, but it is doubtful if any
solvent exactly duplicates the nutrient extractive and
absoptive powers of plants growing in a natural environment.
The reliability of chemical soil tests probably varies
with the nutrient for which the test is being made. Pawlick
and Arneman (l96l)found that total nitrogen content of the
A2 horizon of the soil was negatively correlated with jack
pine growth. However, available phosphorus in the A2 hori-

zon and exchangeable.potassium in the B horizon were signif-
icantly and positively correlated with the growth of jack
pine. Baur (1959) found a correlation between the amount

of phosphorus in the soil and in the leaves of slash pins

in Australia. Walker (1956) also found a relationship
between soil potassium and percent potassium in the leaves
Of several tree species.

Foliar or tissue analysis is favored by many forest
research workers as a more reliable method of determining
nutrient needs (Heiberg and White, 1956; Mitchell, 1936;
Swan, 1960). Fowells and Krauss (1959) agree that the
analysis of the foliage of plants is widely accepted as an
indication of nutrient levels of the soil. Ovington (1956)

believes that foliar analysis may be useful in interpreting
the general availability of plant nutrients in a forest soil.
In England, much attention has been paid to foliar diagnosis

because of the well-known limitations of soil analysis

21
(Goodall and Gregory, 1947; Layton, 1957a). This approach
has been widely applied to agricultural and horticultural
crops, and investigations have confirmed the potential
value of foliar analysis in the study of the mineral require-
ments of forest trees. V

From the diagnostic point of view, Leyton (1957a)
reports that a stage has now been reached where foliar
analysis, carried out with the necessary precautions as to
sampling, would appear to provide a reasonably consistant
guide not only to the nature and extent of particular min-
eral deficiencies limiting tree growth, but also to the
interpretation of field observations. Foliar analysis is
more straight-forward to test and more subject to direct
interpretation (Gessel and Walker, 1958).

According to white (1958c), analysis of the current
year's foliage from the top of the crown during the dormant
period for conifers, or before autumn leaf coloration in
hardwoods, most closely approximates an expression of soil
fertility levels or correlates with the growth response of
individuals to site or treatment. For major elements in
the range of greatest interest, relationships between supply,
tissue content, and growth are sometimes remarkedly straight-
forward (Stone, 1958). Kramer and Kozlowski (1960) say that
with proper safeguards and within certain limits, analysis
of plant tissue are good indicators of the nutrient status
of plants. The leaves of trees are particularly sensitive

indicators of nutrient supply.

The chief advantage of tissue analysis over soil analysis

22
as a diagnostic technique, is that the nutrient content of
the tissue reflects the actual availability of the soil
nutrients to the plant, since the elements have actually
been absorbed by and translocated from the roots (Mitchell,
1936). The tree acts both as the extracting and sampling
agent insofar as the soil nutrients are concerned. Such
items as root extension and penetration, the relative con-
centration of the available forms of the nutrients, soil
properties, and root competition are taken care of auto-
matically.

Some objections to, or disadvantages of foliar analysis
have been noted by Kramer and Kozlowski (1960) and more
particularly by Wilde (1958a). Kramer and Kozlowski (1960)
point out that foliar analysis faces two difficulties; one,
the problem of deciding what constitutes an adequate amount
of an element; and two, that the presence of a certain
amount of an element in plant tissue does not guarantee its
availability for physiological processes. They cite the
example of plants showing symptoms of iron-induced chlorosis
with as much iron in the leaves as normal plants. Apparently
some of the iron was tied up in an unavailable form in the
tissues themselves.

Wilde (1958a) points out that foliar analysis cannot
be used to determine the nutrient status of cutover or
denuded land where there are no trees to be analyzed. Foliar
analysis of young plantations on depleted former agricultural
land may not give reliable information on potential fertility

because the root systems have not had time to penetrate to

23

possibly more fertile layers. Sampling for foliar analysis
of hardwoods must be restricted to a relatively short period'
of time after the leaves have matured, but before transloca-
tion has occurred from the leaves back into the stem. The
relative concentration of nutrients in the leaves may reflect
outside environmental influence that does not reflect the
true fertility of the area, or the.concentration may be
greater due to luxury consumption. However, most of Wilde's
objections are to special conditions that can be taken into
consideration without affecting the validity of the method.

Certain considerations must be taken into account to
make the sampling of foliage for analysis both standard and
valid. For instance, concentration of the nutrients in the
leaves varies according to the location of the leaves on the
tree and to their morphological development (season of
sampling)(White, 1954). Leyton and Armson (1955) found that
the leaves at the top of the trees had a higher concentration
of nutrients than those further down. White (1954) found
that potassium content in white pine needles decreased from
the top toward the bottom of the crown. The age of the
leaves affects the nutrient concentration. Period of rapid
growth are characterized by rapid accumulations of minerals.
After maturation but before senescence, the level of the
nutrient elements remains relatively stable. However, after
senescence, there is some translocation of the nutrients
back into the stem, and losses often occur at that time due
to leaching by rain (Kramer and Kozlowski, 1960).

The optimum concentration of nutrients in the leaves

24

differ with different species, reflecting possibly a varia-
tion in the physiological requirements of the species in
question. losses of nutrients may also occur with improper
handling of the leaf samples due to metabolic activity in
the leaves after their removal from the tree (Kramer and
Kozlowski, 1960). Disease or insect attacks affect the
concentration of nutrients in the leaves and such leaves
should not be sampled (Goodall and Gregory, 1947). Envi-
ronmental conditions such as light or water supply may
possibly affect the nutrient concentration either up or
down (Goodall and Gregory, 1947) although Mitchell (1934)
maintains that the total quantity of nutrients absorbed by
the tree varies with the external supply and is relatively
independent of other environmental factors, at least as far
as nitrogen is concerned.

Careful standardization of sampling procedure plus
field tests and greenhouse experiments to determine optimum
nutrient concentrations in the leaves of all important
species should resolve most difficulties experienced with
tissue analysis (Gessel and Walker, 1958).

An optimum quantity of each essential nutrient is
necessary to achieve the best possible tree growth. The
three major elements; nitrogen, phosphorus, and potassium
are however the most often limiting. It is not to be in-
ferred that the other nutrients should be forgotten when
considering a forest site where a deficiency is suspected.
Marked magnesium deficiencies have been noted in New York

State (Stone, 1953), and zinc, copper, and boron deficiencies

 

25

elsewhere (Benzian and Warren, 1956; Smith, 1943; Smith and
Bayless, 1942).

In summary, it should be emphasized that in evaluating
a forest site to determine the conditions that are limiting
growth, no one factor should be considered to the exclusion
of all others. One or several of the many interrelated-
factors that affect growth may be limiting. However, in
most situations, a relatively few of the factors‘are fre-
quently dominant. Of these factors, soil moisture is most
often in short supply, although deficient nutrients are an

often overlooked situation.

_ CHAPTER Iv
DESCRIPTION OF THE STUDY AREA

The area studied in this investigation is a portion of
a 20-acre mixed yellow-poplar - catalpa plantation established
in 1938 (Fig. 1). The plantation is one of several found in
the Fred Russ Forest located in Volina Township, Cass County,
in southwestern Michigan. Originally a part of the Newton
Farm, this 580-acre area was donated in 1942 to Michigan
State University by the late Fred Russ of Cassopolis, Michigan,
and has since been managed by the Department of Forestry
for experimental and instructional purposes.

The Newton Farm was an early government land grant that
remained under family ownership for 99 years. Cultivation
was intensive without regard to better agricultural practices
such as fertilization or crop rotation. As a result, the
soil on the area, became so badly depleted and unproductive
that the owners were unable to produce paying crops of corn
and wheat.

In June 1935, 580 acres of the Newton properties.were
acquired by Mr. Russ. Of that area, 240 acres were in wood-
lands, 160 acres of which were relatively undisturbed old-
growth mixed hardwoods. By 1951, 320 acres of the former
fields had been planted with either coniferious or hardwood
trees.

The study area is located near the southern boundary of
the forest and has almost level terrain punctuated by occa-

sional shallow depressions. Drainage is good to moderately

26

27

Figure 1. - Map of yellow-poplar plantation showing the

study area and surrounding lands.

Compartment F

The Fred Russ Forest
Vblina Township - Cass County, Michigan

LEGEND:

L.

 

1/8 mile east and 1/2 mile

 

 

 

 

 

 

 

 

 

 

 

 

sub-compartment number (62) .g.
Sub-compartment boundary r4
B‘oundary of study area . . .. . g
Good growth area g
Poor growth area p S
Hardwood influence line ——————— _g
Woods road' : :: : :2 p
Old-growth mixed hardwoods @9890 ‘5
‘nge :
Scale — l" = 300'
"'- " M n m
3 Mixed Hardwood g-lfegwma mg? w?» @w
I! Plantatiém 9‘2qu 18:3} ‘3 O 55%}ng C
H (9%;(3QQ ‘F: PJ 0' Q? @530
_________ _1L_ _. ._ ._ _ _ __ ._. __ _ _ ____",,___:f giggly-‘93 @(L ___—_
...—V - ‘- 91- -- — — ——-—— “'4
(631) i
Yellow-poplar
Plantation
Yellow-poplar Yellow-poplar
Plantation Plantation
20 Acres
(511) Spacing 7' x 14'
(62) (632)
i
(633) A ‘
(E9U? Qifé‘fiaeic
.. ix. -x> :(C\ r???" Cg:

 

 

28

good with the possible exception of slightly poorer drainage
in the depressions.

The soils are of glacial origin, formed from sandy drift
deposited in an outwash plain between the inner and outer
(ridges of the Kalamazoo Moraine. They are included in the
Gray-brown Podzolic soil group, and in this area are gener-
ally free from large boulders or stones. In the plantation
itself, the soils have been classified as acid variants of
Fox sandy loam and Warsaw sandy loam (Fig. 2).' Although
these soils are closely related structural types, the Warsaw
was originally a prairie soil while the Fox series supported
a hardwood forest cover. A complete description of these
two soil series appears in the appendix.

The climate of southwestern Michigan is moderate with
an average annual temperature of approximately 50° F., and
an average annual rainfall of approximately 35 inches.

The growing season has an average of 162 frost free days,
extending from may to mid-October. Mean temperature during
this period is about 65° F. A

The study area is approximately 100 miles south 0f the
northern limit of the yellow-poplar range. ‘Yellow-poplar
is found as a small but important component of natural stands
in the vicinity of the study area, with individual trees
having achieved excellent development.

In the spring of 1938, home-grown yellow-poplar seedlings

of local seed origin were planted 14 feet apart in rows 7

feet apart on the study area. The plantation was cultivated

during the first summer. A year later, catalpa trees were'

Figure 2.<- Soil map of the study area, located in a y
poplar plantation, Compartment F, Fred Russ Forest, Cass

29

County, Michigan.

LEGEND

Soil type line

Good growth area

Poor growth area

Hardwood influence line separating

the two growth areas

Study area boundary

Woods road
Old-growth mixed hardwoods

Scale
1" = 100'

 

 

 

 

\
O _‘...-——--‘_‘_\
Warsaw loam, /////' )
acid\variant /////,
\ ",,
//// ‘
|
' P
!
\
FOX sandy loam, acid variant
\
\
\,__.~ ._. ’0
s '''''' 1*
L: i 27:? Wig-9Q C} a} 9:, 5,34 3; ('3
Q; tug; fipfi3 é)! ~{’pfiw;.k~yn&f}rt
Lgpa{)g}ht @{3 ‘L‘ 3:93?‘ <3?"th Q.)
a; “£32 (32.54.13 m ‘d C.) (“5-8 1.13)..)

 

30

planted between the yellow-poplar within the rows. No
cultivation was done during the summer of 1939. 'The rows
were staggered in such a fashion that a catalpa was’located
on either side of a yellow-poplar tree. After four growing
seasons, the bulk of the yellow-poplar were four to eight'
feet tall with some reaching twelve feet. Survival of the
catalpa was poor, and by the time of the present study,
nearly all of it had disappeared from the plantation.

On the south and part of the west sides of the plantation
is an old-growth stand of mixed hardwoods (Fig. 3). By 1950.
the yellow-poplar immediately adjacent to the hardwood stand
and within the range of its influence was noticeably better
in form, size, and vigor than the trees in the interior of
the plantation (Figs. 4 and 5). Average height of the better
growing trees is now over twice the average height of the
poorer growing trees, and average diameter is approximately
one and one-half time larger. The trees closest to the
hardwood stand showed the greatest growth, and size decreased
row by row until uniformly poor trees are found approximately
eight to nine rows north and nine to ten rows.eaat of the
woods (Fig. 6). The actual study area consists of an ap-
proximately 4-acre rectangular block in the southwest cor-
ner of the 20-acre plantation (Fig. 1). This block’includes
a little less than two-thirds of the good~growth area, and

a representative portion of the poor-growth area;

51

 

.menm more» voow an» op .80.» some you»:
me magmas“. oapmaouwmmoo ovum camp» 35. .memm human 23 no one: cow some».
23 3 no: as: e53 396.8: 35... insane? 23 mo flea . .n 98m:

k .. ,. 9/1J.....H.\Iur.fl... . I A) .5,

y

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fl ‘ l ‘,
a . V
y I .. ‘\",". a»: V '
\ ,‘ 2 . ,
. .. my “ of. ,‘X i‘
f ) ‘ u v _ ,
‘ '\. f' " " ‘1
\ .I\ 1 -’7 ‘. “y l “
¢ I. .11} .’ . s“):
1 N j 3,. , x ,,
' Lg. '7‘ n
r ,h 'd \ \ ‘-
' , . ,V ”v- ‘1 v . ..
( (.\ .\~. I I1
1 x d V
1 \ " K
‘ '1'" 4. t...
“1H _ ‘3. H ‘
, “ ) " l ’ U ‘b
r \ , | .f - _ A
f ‘ i l ‘ \ ’ 7" ..
_ ,: ‘ , . 3:. . re
\»3 ~.' \ ‘ A ‘ .-'
; Tfii _ ~
. ~ I ‘ N '
N} ‘ ~‘ ~ ‘
. ‘ \
a , s.» ,
k; ?
i l

 

 

Figure 4. - Winter aspect of the southern edge of the good

growth area showing the excellent form of the yellow-poplar
trees, typical of that area.

 

 

 

 

 

Figure 5. - Winter aspect of a typical portion of the poor
growth area showing the relatively small size and poor form
of the yellow-poplar trees.

 

 

 

 

 

 

 

 

 

 

 

Figure 6. - An oblique view through the study area showing
the decreasing total heights of the vellow~poplars, from
the good growth area in the foreground to the poor growth
area in the background.

 

CHAPTER V
PREVIOUS EXPERIMENTAL WORK ON THE STUDY AREA

In June 1951, a study was instituted by the Department
of Forestry to determine the reason for the markedly differ-
ential height and diameter growth of yellow-poplar trees be-
tween two parts of this 20-acre plantation. Both parts of
the area had been planted in the same year, at the same
spacing, with seedlings from the same stock, and apparently
had identical previous treatment of the land. The work was
undertaken by R. D. Shipman and the results used for a Ph.D.
dissertation (Shipman, 1952) and later for a technical bul-
letin (Shipman and Rudolph, 1954).

Shipman made a detailed ecological investigation of the
edaphic and microclimatic factors present in both parts of '
the plantation. Evaporation rates, air temperature, and
relative humidity were measured at each of four climatic
stations, two in the portion of the plantation that exhibited
relatively good growth and two in the portion showing poor
growth. In addition, soil moisture was measured at depths
of six and eighteen inches by means of Bouyocous soil mois-
ture blocks, and soil temperature was taken at a depth of
one inch near each of the above four stations. Besides the .
above factors, a number of soil determinations both physical,
chemical, and microbiological, and several ecological deter-
minations, were made over the study area. The physical soil
data included total, capillary,and non-capillary porosity;

volume weight, maximum water-holding capacity, specific grav-

35

36
ity, hygroscopic coefficient, soil moisture evaporation, and
mechanical analysis. Chemical soil determinations included
organic matter content, exchangeable hydrogen, total bases,
pH, total nitrOgen, carbon-nitrogen ratio, base exchange ca-
pacity, and the nutrient element content of the individual
soil horizons. Soil microorganisms were cultured to show
seasonal variation, populations by soil horizons, relation to
pH, relation to moisture content, and numbers of fungi, bac-
teria, and actinomycetes as related to the ecology of each
area. Finally, depth to the water table throughout the sea-
son, kind and extent of forest litter, concentration and po-
sition of roots in the surface soil horizons, light intensity,
the effect and extent of sun scald injury, and a tally of the
ground vegetation were measured.

Shipman's analysis of the physical soil characteristics
showed that very little difference exists between the two
areas in that respect. Statistical tests showed no significant
difference between the specific gravity, hygroscopic coeffi-
cient, capillary porosity, non-capillary porosity, total po-
rosity, volume weight,or moisture equivalent for any of the
soil horizons of the two areas. The mechanical analysis re-
vealed a difference in the amount of fine clay present in the
A1 and A2 horizons, with the soils in the area of poor growth
having a slightly higher amount.. The difference was statis-
tically significant at the one percent level. A difference
was also found in the maximum water-holding capacity between
the A2 horizons of the area of good growth and the area of

poor growth. Both sieved, air-dried soil samples and soil

37
cores (fundisturbed" samples) were used in this determination.
The area of poor growth showed a significantly higher maximum
water-holding capacity, at the one percent level for the
sieved samples and at the five percent levei using the soil
cores, than the area of good growth. The higher maximum water-
holding capacity may be linked to the higher fine clay con-
tent found on the area of poor growth.

Shipman points out that on the basis of the significant
differences in physical properties that he found, and on the
basis of some non-significant differences, the area of poor
growth has slightly better physical soil properties than the
area of good growth. Therefore, if the physical aspects of
the soil were the limiting factors, then the better growth
should exist on the area of actually poor growth. Since this
is not the case, he stated that those physical soil proper-
ties tested are not limiting to growth.

Soil profiles were dug near each climatic station, five
times during the growing season, beginning April 18 and end-
ing August3l, and lateral root penetration was examined.
Lateral root penetration averaged 13.4 and 11.8 inches at
the two stations in the good growth area, and 12.4 and 17.2
inches at the two stations in the poor growth area. Average
depths of lateral root penetration did not differ-appreciably
between areas. The station with the deepest root penetra-
tion was also reported as the driest portion of the site,
and the place where the water table is closest to the sur»
face. Quantities of roots at various depths were not re-

ported.

38

The water table showed a continuous drop from April to
August. This is, however, a normal condition during the
summer when evapotranspiration losses are the heaviest and
recharge from summer showers is usually not sufficient to
replenish the losses. Shipman found that the average depth
to the water table was three feetin the area of poor growth.
as opposed to six feet in the area of good growth. He attrib-
uted that difference to the heavier drain from the larger
trees in the area of good growth.

Of the various chemical soil determinations, Shipman
found no difference in pH, percent organic matter, total
nitrogen, nitrogen-carbon ratio, cation exchange capacity,
total bases, and exchangeable hydrogen. In addition, the
soil tests failed to reveal any difference in the amount of
available calcium, magnesium, iron, and manganese or ex-
changeable sodium between the two areas. Three significant
differences did exist in the chemical soil preperties, how-
ever. The percent base saturation of the C horizon in the
area of good growth was somewhat higher, and the difference
was statistically significant at the one percent level. This
difference may be of somewhat doubtful value in explaining
growth differences since the Cahorizon is probably beyond
the level of significant root penetration.

Possibly of greater importance was the significantly
greater quantity of phosphorus in the 32 horizon of the
good growth area as compared to the poor growth area. Po-
tassium was also present in greater amounts in the A and B

horizons of the area of good growth. Since both of these

39
elements are major essential nutrients, the differences in
the amount present between the two areas of the plantation
may have had an important effect on the growth differential
found there.

The difference in phosphorus content of the soil is es-
pecially noteworthy. Shipman's results showed that in the
upper three horizons (A1 through the 82 ) in which the bulk
of the tree roots are located, the soil had nearly twice as
much "available“ phosphorus in the good growth area as in
the poor growth area. This averaged out to be .07 millequiv-
alents per 100 grams of soil as opposed to .04 millequivalents
per 100 grams of soil. While it is not currently known if
this difference is actually significant in terms of better
tree growth, the possibilitv does exist that phosphorus may
be a strong factor in the growth difference of the two areas.
This is particularly true if phosphorus becomes limiting some-
where between the above two values. .

n'A stem analysis of selected trees from both areas showed
a strong positive correlation between annual precipitation
and annual height growth for both areas fer the 1941-1951 pe-
riod. A similar correlation between diameter growth and
precipitation was found although it was not as strong.

An examination of the sunscald damage in the area of
poor growth showed that it had no effect on the height growth
of the trees.

During the 1952 growing season, Shipman made a survey
of the ground vegetation to determine if some relationship

to the soil moisture regime could be found. A correlation

40

between species present and the available soil moisture in the
surface six inches was established.

Air temperatures were consistently higher in the area of
poor growth, varying from a matter of 2 or 3° F. to nearly
15° F. .However, air temperatures in either case were not in
the range that could be considered damaging, although they
would have the effect of increasing transpiration rates in
the area of poor growth as Opposed to the area of good growth.

Surface soil temperatures showed even more variation be-
tween areas. Temperatures were as much as 20° F. higher in '
the area of poor growth. Again, temperatures did not reach
a lethal level but were probably important in increasing soil
moisture evaporation from the surface soil. Relative humidity
was generally somewhat lower in the area of poor growth which
would tend to increase transpiration in this part of the plan-
tation. Evaporation from the soil surface was also consistently
higher in the area of poor growth. ,

Finally, soil moisture levels varied at both the 6- and
18-inch depths between areas. The greatest difference occurred
at the 6-inch depth where soil moisture levels were signifi-
cantly lower in the area of poor growth. However, there were
extended periods during which little or no difference occurred,
and moisture levels did not fall below 70 percent in either
area during the 1951 season. At the 18-inch depth, the actual
differences were not as great, although the variation was
statistically significant between areas.

Highly significant (at the one percent level) differences

were found for all the microclimatic measurements between the

41

areas of good and poor growth, with the exception of the per-
cent available moisture at the 18-inch depth for the 1952 sea-
son. This latter measurement showed a significant difference
at the 5 percent level and was in favor of the area of poor
growth. Measurements of light intensity were inconclusive,
although average light intensities were considerably greater
in the area of poor growth. '

From these data, Shipman concluded that the difference
in height growth between the two areas was a function of an

improved moisture regime in the anea of good growth resulting

from the more extreme microclimatic conditions of the area of ,

poor growth. He stated that "the height growth of the trees
in the two contrasted areas is conditioned by factors which
are obviously associated with the water utilization of the
tree." "Any of these factors which affect the soil moisture
regime are reflected in height growth and over a period of
time will define site quality." He continues, "the micro-
climatic dsta presented here are aggregate verification of
the fact that available moisture is the limiting factor in
producing a differential height growth of plantation-grown
tulip-poplar” (yellow-poplar). "This is not to imply that
the tulip trees in the area of good height growth are nec-
essarily receiving greater amounts of moisture, but rather
that the trees in this area are able to utilize the moisture
more effectively due to a set of interrelated site conditions

not found in the area of poor growth."

CHAPTER VI
METHOD3 AND PROCEDURES

Observations of certain tree characteristics in the
poor growth portion of the study area indicate that a severe
nutrient deficiency may exist there. Leaves tend to be
small and in many cases were definitely cthrotic, suggest-
ing a nitrogen deficiency. Bronzing of some leaves was also
noted, which is a phosphorus deficiency symptom. In con-
trast, the leaves in the area of good growth were consist-
ently larger, with a healthy-looking medium to dark green
color. In addition, it was observed that the leaves in the
poor growth area changed to autumn colors and abscised from
the trees two to four weeks earlier than,in the good growth
area. This phenomenon also suggests a nitrogen deficiency.
Because of these nutrient deficiencies symptoms, this
study was initiated to evaluate the nutrient.regime by both
foliar and chemical soil analyses. In addition, the litter
deposit on both areas was sampled and the nutrient content
determined to measure the annual nutrient contribution from ‘

this source.

‘ Foliar Analysis

Poliar analysis has been generally accepted as a reliable
method of determining the available nutrient statUs of a
forest site. The methods of sampling and analysis were
standardized according to accepted analytical procedures,

80 that the trees in the present study could be compared to
each other, and to the normal or optimum concentration of

42

43
nutrient elements established for yellow-poplar leaves in
other studies.

Chemical composition of tree leaves varies according
to their position in the crown, physiological age of the
leaves, and the effect of insect and disease incidence, as
well as by species and the concentration and availability
of nutrients in the soil (Leyton and Armson, 1955; White,
1954). The technique of sampling fully mature leaves from
the south side of the tree near the top of the crown, as .
advocated by Mitchell (1936), was used in this study.

In mid-September, 63 trees were systematically sampled
in a grid-like fashion covering the areas of good and poor
growth over the 4-acre study area, plus the intermediate
area between the two. The topmost branch on the south side
of the tree below the terminal was clipped off with a pole
pruner. Thirty mature leaves that did not show signs of any
abnormalities due to insects or diseases were stripped off
the branch and put in a numbered kraft paper bag.

The leaves were oven-dried at 70° 0., the petioles re-
moved, and the leaves ground in an intermediate Wiley mill
until the material could pass through a 20-mesh screen. The
ground leaf material was placed in clean two-ounce Jars and
again dried at 700 c. in an electric oven for 36 hours.
The samples were analyzed for total nitrogen by the micro-
kJeldahl method; for potassium using a Coleman model 21
flame photometer; and for phosphorus, calcium, magnesium,
manganese, iron, copper, boron, zinc, molybdenum, and alu-

minum using a Quantograph photoelectric spectrometer. De-

' 44

scriptions of the analytical procedures are included in the

appendix.

Litter Analysis

Since the area of good growth was_suspected of having
a more favorable nutrient regime than the area of poor growth,
the source and magnitude of the additional nutrients on the
good growth area were investigated. Soils on both areas
appear to be essentially similar, and there is no evidence
of a variation in past land practices. It was hypothesized,
therefore, that the greater annual deposit of litter on the
good growth area from the adjacent old-growth hardwoods
contributed to the improved nutrient regime of that portion
of the plantation. I

To determine the quantity and chemical composition of
the litter deposited on both parts of the study area, samples
of the current year's leaf fall were collected in late Octo-
ber from points six feet due east of each sample tree.- A
metal sampling quadrat covering an area of 2.12# square feet
(l/20,000 of an acre) was placed on the litter surface at
each sampling point and all of the current year's litter
deposit was collected. Where the edge of the quadrat cut
across individual leaves, these leaves were divided with a
sharp knife and only the part inside the sampling device
was taken.

In this method of sampling, some nutrients were prob-
able lost by leaching, and some decomposition of the litter

may have occurred before sampling. This would result in a

45
slightly lower estimate in the total quantity of litter in
both areas. However, the-proportion between the two areas
should have remained the same. Little addition to the litter
deposit occurred after the sampling date, because an ice
storm had removed even the most persistent leaves from the
surrounding trees a few days before.

The litter samples were oven-dried at 70° C. and weighed
to the nearest 0.1 gram. The samples were then ground in an
intermediate Wiley mill, again oven-dried at 70° 0., and sub-
jected to the same analytical procedure as the fresh leaf

samples (see appendix).

Soil Sampling and Analysis

Sixty soil samples were taken on the study area to de-
termine if differences in the nutrient regime could be found
between the area of good and poor growth. A different sam-
V pling procedure from that previously used by.Shipman (1952)
was applied. Each of the two contrasting growth areas was
divided into three equal parts, and five sampling locations
were randomly spotted in each part. At each location, the
soil was sampled at a depth of 2 to 5 inches, and a depth
of 18 to 21 inches. The 2- to S-inch depth sampled the
middle of the A horizon, and the 18- to 21-inch depth sampled
the middle of the B horizon. The soil was placed in a stand-
ard soil sampling bag, and then thoroughly air-dried. To
prepare the sample for analysis, the air-dried soil was passed
through a 2-millimeter screen to remove the gravel.

Total nitrogen determinations were made using the stand-

ard Kjeldahl procedure. Phosphorus, potassium, calcium, and

46.
magnesium were determined by the Michigan State University
Soil Science Department's soil testing laboratory. In their
procedures, phosphorus was extracted with Bray‘s number one
solution (ammonium floride-hydrochloric acid mixture). F-S
powder and ammonium molybdate were added to the extract to
bring out the color, and the color of the solution was read
on a Bausch and Lomb colorimeter.
Potassium, calcium, and magnesium were extracted with
1.0 normal, neutral ammonium acetate, which replaced the re-
serve method (0.13 normal hydrochloric acid) formerly used
12y the soil testing laboratory. The potassium and calcium
eaxtracts were determined on a Coleman flame photometer and
tshe magnesium extract analyzed with a Beckman D-V flame photo-’
meter .
A 1:1 ratio of soil to water was used to determine pH
Lasing a Beckman pH meter. Base exchange capacity was calcu-

lxated from the sum of the bases plus hydrogen.

Statistical Analysis

Differences in the nutrient content of the leaves, height,
and diameter of the sample trees, quantity and chemical compo-
sjstion of the litter, and the chemical soil analysis between
the area of good growth and the area of poor growth were tested
by’ the analysis of variance method.

The following design was used in testing the nutrient
corltent of the tree leaves and the quantity and chemical oom-

DOSition of the litter.

47

 

 

Source of Variation Degrees of Freedom
Total variation 49
Between areas ‘ 1
Error 48

The following design was used in testing differences be-

tween areas for the chemical soil analysis.

 

 

Source of Variation" Degrees of Freedgg
Total variation 29
Between blocks 5
Between areas' 1
Error ' 23

A correlation analysis was made between both heights and
diameters of the sample trees and each of the determinations
(If the 12 nutrient elements. The data were processed by the
”Ilystic" analytical computer, owned by Michigan State Univer-
sity and operated by the Department of Electrical Engineering.
Tfiais computer determined the correlation between height, diam-
eter: and each of the 12 nutrient elements, and also between
each of the nutrient elements themselves. Data from 63 sam-

Ple trees were used.

CHAPTER VII
RESULTS AND DISCUSSION

Leaf analysis

Analysis of the yellow-poplar feliage revealed a highly
statistically significant (at the one percent level) differ-
ence between the nutrient element concentration of the
leaves of the trees in the area of good growth and the area
of poor growth (Table 2). This difference was found for

every nutrient analyzed, except boron and magnesium. In

every case where a significant difference did occur, the
level of concentration was higher in the leaves from the
area of good growth. Aluminum, a non-nutrient element, did
not differ significantly.

The most outstanding differences, both statistically
and in actual nutrient levels, were found for nitrogen and
phosphorus concentrations. Both nutrients had nearly twice
as high a quantity in the leaves in the area of good growth
as in the area of poor growth.

Heights of the sample trees in the good growth area
averaged over twice those in the poor growth area, and
nutrient concentrations were positively correlated with
this difference. NitrOg-en and phosphorus showed the strong-
est correlations with tree heights.

Similiar correlations between tree diameter and nutri-
ent concentrations were found for all elements that showed
significant differences between areas, except potassium

(Table 3). Again, nitrogen and phosphorus showed the

48

49

Table 2. - Analysis of differences. in height, diameter, and
leaf nutrient levels of yellow-poplar trees in southwestern
Michigan

 

 

 

Tree location

Tree characteristic "F" value
Area of Area of

good growth poor growth

 

 

feet

Height 57.5 26.6 125.11'*
inches ' **

Diameter 7.38 3.99 47.32

Leaf nutrient level+

percent of oven-dry leaf weight **

Nitrogen ' 1.75 0.95 122.72
Potassium 0.890 0.672 17.62“
Phosphorus 0.196 0.101 68.62’*
Calcium 3.18 2.76 7.52**

Magnesium 0.318 0.291 2.37
ppm - oven-dry leaf weight *.

Manganese 471 345 7.99
'Iron 122 87 53.61**
Copper 10.3 ' 7.7 64.62""*

Boron 72.2 72.6 0.00
Zinc - 32 27 30.37‘*
Molybdenum 12.0 10.5 8.83"

Aluminum 402 437 2.96

* Based on 25 trees sampled in each area of growth-
*" Significant difference at the one percent level.

+ Nitr0gen determined by the microkJeldahl method, potassium
determined by the flame photometer, and the remainder of
the elements were determined using a photoelectric spec—
trometer. °

5O

strongest correlations, although all correlations with

diameter were less than between nutrients and height.

Table 3. - Correlation coefficients between height and dia-
meter of yellow-poplar and the level of leaf nutrient
concentrations - ‘

 

 

Tree size ‘ Leaf nutrient level

 

“Major elements" '
. P N Ca K Mg

Height ' +.764** +.748f" +.466“ +.297‘" +263."
Diameter +.684** +.647** +.433“ +.150 +.l93

"Micro-elements"
Fe Cu Mn Zn Mo B
Height ,+.551** +546” +.472“ +.477" +.371M +.065

Diameter +.342** +.4l3** +.418** +.275** +.336‘“ +.107 "

 

** Significant at the one percent level.
* Significant at the five percent level.

Based on the leaf analysis of the yellow-poplar trees
on the study area, there appears to be a definite and highly
significant difference in the soil nutrient regime between
the area of good growth and the area of poor growth.. or
theitwelve elements tested, only magnesium, boron, and
aluminum did not differ significantly between areas. Aluminum
1 13 not considered an essential nutrient element and was

routinely in cluded in the spectographic analysis by the

51

Department of Horticulture because it is sometimes found in
highly toxic quantities in fruit trees. Both boron and

magnesium are essential elements which are sometimes limit-
ing (Smith, 1943; Stone, 1953) but since the concentrations
do not differ appreciably between the two growth areas, it
is doubtful that either element could be considered limiting
in this instance. Actually leaf concentrations of both
elements are relatively high (Kramer and Kozlowski, 1960).
For the major nutrient elements, nitrogen and phosphorus,
the situation is very clear. Not only was there a highly
statistically significant difference in the leaf composition
for these nutrients between the trees of the good and poor
growth areas, but the concentrations in the leaves from a

the poor area were found to be severely limiting. This

is especially-noticeable in the case of nitrogen, and only
slightly less so for phosphorus. Many of the trees in the
area of poor growth exhibit chlorosis and small leaf sizes
typical of a nitrogen deficiency. A bronzing of some leaves
was also noted which is typical of phosphorus deficiency in
citrus trees (Camp et a1., 1941). Phosphorus-deficient
yellow-poplar seedlings in a recent greenhouse study, also
exhibited this condition l/.
Nitrogen composition of the leaves from sample trees
on the area of good growth ranged from a low of 1.35 to a
tligh of 2.21 percent, with an average of 1.75 percent. .0n

‘She area of poor growth, leaf compositions ranged from a

 

i:/ Finn, R. F. 1961. Project Leader, Central States For.
- Expt. Sta., Ames, Iowa. personal communication.

52

low of 0.54 percent to a high of 1.41 percent, with an
average of 0.95 percent nitrogen.

Mitchell and Chandler (1939) consider a range from
2.15 to 3.00 percent nitrogen in yellow-poplar leaves as
optimum for growth. Normal trees growing naturally on a
variety of sites had leaf concentrations of 1.70 to 2.33
percent nitrogen with an average of 2.04 percent (Table 1,
p. 15). In the southeast, nitrOgen concentration of 1.08
percent in yellow-poplar leaves is considered deficient by
Wells (1961). Other studies that analyzed yellow-poplar
leaves from trees with normal growth, showed nitrogen
composition levels of 1.50, 1.85, 1.40, 2.54, 2.29, 2.32,
and 1.31 percent of dry leaf weight (Bard, 1946; Finn, 1953).
It is obvious that the good growth area may be somewhat
below optimum in nitrogen level and the poor growth area
is severly deficient in that nutrient.

Phosphorus content of the yellow-poplar leaves in this
study averaged 0.196 percent of dry leaf weight in the good
growth area and 0.101 percent in the poor growth area (Table
2). Deficiency levels for phosphorus in yellow-poplar have
not been as clearly defined as for nitrogen. Past work has
shown concentrations of this element in the leaves of
yellow-poplar without indicating either optimum or deficient
levels (Table 1). Phosphorus leaf concentrations for trees
other than yellow-poplar have, however, been determined for
both normal-appearing and deficient specimens. Based on
this information, Phosphorus concentrations in the neighbor-

hood of 0.20 percent dry leaf weight may be considered

53

adequate for normal if not optimum growth. On this basis,
the poor growth area with its 0.101 percent concentration,
is deficient in phosphorus.

Results of the leaf analysis are corroborated by un-
published datal/ from a fertilizer eiperiment on a nearby
yellow-poplar plantation on the Russ Forest where trees
show a marked response to applications of a complete ferti—
lizer. Three-year height growth of the trees averaged over
two and—one-half times as much on plots fertilized with 336
pounds of nitrogen, 168 pounds of potash (K20), and 168
pounds of phosphate (P205) per acre as compared to the
unfertilized controls. Diameter growth averaged three times
as much on the fertilized plots compared to the control
plots.

Leaf nutrient concentrations averaged 1.90 percent
nitrogen, 0.186 percent phosphorus, and 0.78 percent potass-
ium on the complete fertilizer plots, on a three-year basis,
as compared to three-year averages of 1.46 percent nitrogen,
0.150 percent phosphorus, and 0.86 percent potassium on the
control plots. The trees on this area had shown the same
nutrient deficiency symptoms as the trees in the poor growth
portion of the present study area, but to a lesser degree.
After fertilization, leaf sizes increased noticeably, and
the leaves became a healthy, darker green color. Autumn
coloration and leaf fall were also found to be delayed for

the trees on the fertilized plots as compared to the un-

 

lTWhite, D. P., and R. F. Firm 1961. op. cit.

54

fertilized controls.

Differences in leaf concentration of potassium, al-
though highly statistically significant between the good
[and poor growth areas, are not as great as they are for
phosphorus and nitrogen. Potassium averaged 0.890 percent
dry leaf weight in the area of good growth, and 0.672 per-
cent in the area of poor growth. The deficiency level for
this element has not been clearly defined for yellow-paplar.
However, on the basis of information available for other
species, potassium concentrations of approximately 0.80
percent of dry leaf weight are considered sufficient for
normal growth.

White and Finn'sl/ fertilizer study of yellow-poplar,
showed potassium concentrations of 0.86 percent in the
leaves of trees on the control plots, based on a three-year
average. Additions of 168 pounds of potash (K20) per acre
resulted in only a small increase in leaf concentration
(0.03 percent) and no significant increase in height and
diameter growth. Application of fertilizer with 336 pounds
of nitrOgen and 168 pounds of potash (K20) per acre did not
result in a significantly greater increase in three-year
height and diameter growth than an equal nitrogen applica-
tion alone. These results indicate that potassium is
probably not seriously deficient on either the good or poor
growth area in the present study.

The strong, positive correlation of both nitrOgen and

 

17 White, 6. P., and R. F. Finn 1961. op. cit.

55

phosphorus to tree height is shown by their respective high
correlation coefficients of +.748 and +.764 (Table 3; Figs.
7 and 8). A coefficient above +.320 is highly statistically
significant (at the one percent level) for 62 degrees of
freedom; the higher the correlation coefficient, the stronger
the correlation. Potassium had a coefficient of +.297,
significant at the five percent level, when correlated with
height. These results indicate that differences in nitrOgen
and phosphorus levels are highly important in accounting
for the difference in growth between the two areas of the
plantation. Potassium, by reason of its much lower corre-
lation with height growth and the smaller differences in
concentration between areas, is less important.

0n the basis of work done in determining foliage nutri-
ent concentrations in fruit and ornamental trees, manganese,
zinc, molybdenum, calcium, magnesium, boron, iron, and
cOpper are probably not limiting for the trees in either part
of the study area (Bard, 1946; Cannon et a1., 1960; Chapman,
1960, Davidson, 1960; Goodall and Gregory, 1947). Although
optimum or non-limiting levels of these nutrients vary with
tree species, the concentrations of these nutrients in the
leaves of the yellow-poplar for both the good and poor areas
are well above the concentrations generally believed to be
limiting for most species.

The significantly higher concentrations of most of
these elements in the leaves from the good growth area as
compared to the poor growth area probably reflect luxury

consumption by the more vigorous trees in the former area.

56

‘ Figure-7. - Linear regression of percent concentration of
nitrogen in the leaves over the total height of pi7ntation
grown yellow-poplar (Liriodendron tulipifera L.) _ .

 

2.8~a- .
A
. Y = 052 + .019X
2.6 ~—
. B = e305 ,
2'4 h / I /
/.
2.0 w . / / o [/‘x/
e e / . l//. -
#3 1.8 i / . ’,-’. /
:‘Eo . / .
at; ./ ° . /
23 1.6 ..r ./ . 0,: . ‘/
at. / e o. / /
dd ./
::o / _/ .
pH 1.4 - e../. .// . '/ g
52? ./ . .//' /
o'd ./ .. /-’ /
8": 1'2 - / e / .‘ /
040
>
O
1.0 5'
OeB ‘3'. /
/
0-5 ' Standard deviation
of the regression line
Oeh' "' "
/
l
(h?

 

 

10 20 30 40 so . 60 7o 80 90
Total tree height - feet

 

l/ Based on a sample of 63 trees

57

Figure 8. - Linear regression of ercent concentration of
phosphorus in the leaves over tota height of pla tation
grown yellow-poplar (Liriodendron tulipifera L.)l .

.34 .-

'4)
u

.033 + .0026X

.32 '- 3 e038

/ /

/ Standard deviation
/ of the regression line ' /

e30 '-
.28 -
/
e26 "

e24 "'
.22 ~
.20 ~

.18 -

Percent phosphorus
oven-dry leaf weight

e16 "

.14 -

e12 '-

.10 -

e08 " /

 

 

.06 -

 

10 2030 40 50 60 7O 80 90
Total tree height - feet

 

;/ Based on a sample of 63 trees

58

This is definitely not the case with respect to nitrogen,
phosphorus, and possibly not for potassium. As stated
previously, nitrogen and phosphorus leaf concentrations in
the poor growth area are below the level considered to be
deficient, while leaf concentrations from the good area are
well above that level. The situation in regards to potass-
ium is not clear. The difference in potassium leaf concen-
tration between areas is not as great as it is in the cases
of nitrogen and phosphorus. In addition, potassium concen-
tration in either area is within a range where it is not
possible to evaluate a deficiency difference at the present

level of knowledge.

Litter analysis

Over two and one half times as much litter is deposited
annually on the good growth area as compared to the poor
growth area (Table 4). This annual deposit amounts to
approximately 3,000 pounds of organic material per acre on
the good growth area, as against approximately 1,200 pounds
per acre in the poor growth area.

Table 4. - Quantity and nutrient composition of litter on two
parts of a yellow-poplar Plantation in southwestern Michigan

W
Quantity of nutrient elements

 

Area sampled Litter weight 7
N P K Ca Mg

 

pounds per acre
Good area 2,913.6 1421.0 28.2 3.6 5.8 57.4 5.2
Poor area « 1,155.6 1121.4 ' 10.4 1.0 1.4 24.0 2.0

 

59

This large difference in the quantity of litter deposited
on the two areas reflects not only the greater volume of
leaf tissue produced by the denser foliage of the trees on
the good growth area, but also the considerable leaf fall
from the adjoining hardwood stand (Fig. 3) to the west and
south. Prevailing winds in this region are southwesterly.
Only an occasional leaf other than yellow-poplar was observed
in the litter deposit on the area of poor growth, while the
litter from the area of good growth contained numerous
leaves of other species from the adjacent hardwood stand
(Fig. 9).

Not only was the quantity of litter on the good growth
area larger, but in many instances its percentage composi-

tion of nutrient elements was slightly higher (Table 5).

NitrOgen, potassium, phosphorus, manganese, iron, and boron
were found in higher concentrations in the litter on the
good growth area. Conversely, calcium was present at higher~
concentrations in the poor growth area. This latter sit-
uation is probably due to a reduced cell size in the smaller
leaves on the poor growth trees, resulting in a higher _
proportion of cell wall material to cell contents. Calcium
is predominantly found in the cell wall, while the other
nutrient elements predOminate in the protoplasm.

All these differences, although actually small in some
cases, were statistically significant at the one percent
level (Table 5). There were no real differences between

areas in the levels of magnesium, copper, zinc, or molybdenum.

 

6O

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61

Table 5. - Nutrient composition of the litter from two parts
of a yellow-poplar plantation in southwestern.Michigan

 

Sample location
Nutrient element "F" value
Area of Area of
good growth poor growth

 

 

‘percent dry leaf weight

Nitrogen 0.97 0.90 10.03**
Potassium 0.197 0.127 102.89“
Phosphorus 0.126 0.095 89.81““
Calcium . 1.97 2.11 7.11‘“
Magnesium 0.177 0.169 3.62
ppm - dry leaf weight
Manganese 922 480 48.11‘2
Iron 432 268 8.72‘“
Copper 17.9 18.8 0.54
Boron 50.3 36.2 54.24"
Zinc 56 . 56 . 0.08

Molybdenum 7.7 7.9 1.04

 

** Significant difference at the one percent level

It is a well known fact that the annual addition of
organic matter in the form of litter is an important means
of maintaining and improving a forest site. These additions
of organic material not only improve the physical condition
of the soil, but they are also an important source of nutri-
, ent elements.

NitrOgen and phosphorus are the two nutrients most

significantly affected by the higher annual additions_of

62

litter in the area of good growth. Since practically no
nitrogen occurs in soil minerals, all nitrOgen must come
from the atmosphere through additions of nitrates in rain-
water and from nitrogen fixation by microorganisms. Most

of this nitrogen is eventually incorporated in organic
matter, and through decomposition, it finally becomes avail-
able to plants. Thompson (1957) states that about 99 per-
cent of the soil nitrogen is in organic form at any one
time-

Organic matter is also a very important source of the
phosphorus that is available to plants. According to Black
(1957), anywhere from 3 to 75 percent of the soil phosphorus
may be in organic form. For most soils, organic phosphorus
averages about 30 to 50 percent of the total (Buckman and
Brady, 1960). This organic phosphorus is released to the
soil solution through organic matter decomposition, and
becomes immediately available for root absorption. Black
(1957) states that organic phosphorus act as a reservoir
of this element, and the return of inorganic phosphorus
from plant residues constitutes the primary means by which
_ phosphorus availability is increased under natural conditions.

0n the study area, the adjacent stand of old-growth
hardwoods has acted as a source of nutrient-rich litter for
the good growth area for many years. This factor has
contributed to the better nutrient regime in this section
of the plantation. The effect has been cumulative, since
the better nutrient status has resulted in faster growing,

healthier trees which themselves now produce more leaf

63

material, richer in nutrient elements, than the trees in
the poor growth area.

Because of its relatively poor condition, the area of
poor growth produces farless litter than a normal hardwood
stand. Ovington (1956) estimates that a well stocked forest
stand should produce approximately 3,000 pounds of litter
per acre per year. Other stands have been reported as
producing annually from approximately 1,600 to 4,000 pounds

per acre e

Chemical soil analysis

Reappraisal of soil fertility levels based on chemical
analysis revealed little difference in the soil between the
two areas (Table 6). The data showed no statistically
significant difference for any chemical soil characteristic
of the A horizon. For the B horizon, however, both total
nitrogen and available phosphorus content was significantly
different between areas of growth. The difference in
nitrogen was in favor of the poor growth area and in phos-
phorus in favor of the good growth area.

The real difference in nitrogen was not large, .039
percent in the area of good growth as opposed to .050 per-
cent in the area of poor growth. Phosphorus averages .0581
millequivalents per 100 grams of soil in the B horizon of
the good growth area and .0419 millequivalents per 100 grams
in the poor growth area.

The real importance of the total soil nitrogen differ-
ences found in this study is doubtful. Soilanalysis is

64

Table 6. - Analysis of chemical soil differences between two
parts of a yellow-poplar plantation in southwestern Michigan

 

 

Sample location

 

 

Soil characteristic Area of Area of "F“ value
good growth poor growth
A horizon
PH 5.2 5.2 0.000
percent by weight
Nitrogen .093 .092 0.006
millequivalentssggi 100 grams of
Phosphorus .0532 .0467 1.66
Potassium .0974 .0923 0.35
Calcium 2.240 2.195 0.001‘
Magnesium 2.145 2.265 0.034
Exchange capacity 11.3 11.8 2.26
B horizon 8
m 4.9 4.9 0.006
percent by weight
Nitrogen .039 .050 9.796*‘
millequivalents per 100 grams of
soil
Phosphorus .0581 .0419 10.59.‘
(Potassium ‘ ‘ .1320 - .1512 2.43
Calcium 2.815 2.748 0.001
Magnesium 2.298 2.099 ' 0.806
Exchange capacity 14.1 15.4 2.53

 

** Significant at the one percent level

65

considered an unreliable method of determining the amount
of nitrogen available for plant absorption and use during
the growing season. There has been little correlation
between the amount of total nitrogen in the soil and that
absorbed by plants (Bard, 1946; Mitchell, 1934) or between
total soil nitrogen and tree growth (Pawlick and Arneman,
1961).

Nitrogen relationships in the soil are very complex
and are constantly changing. In the surface 6 inches of
virgin forest soils, total nitrogen content ranges between
0.1 and 0.3 percent (Wilde, 1958b), and in the plow layer
of cultivated soils, the total nitrogen content varies '
between 0.02 to 0.4 percent (Black, 1957). Usually less
than two percent of this nitrogen will be in the available
ionic forms at any one time, the rest being in organic
forms (Black, 1957).

The readily available forms of nitrOgen are very
transient, varying from a relatively abundant supply one

day to relatively little or none the next (Thompson, 1957).
Much of this readily available nitrogen is in a very water-
aoluble form and is either easily leached from the soil or
rapidly absorbed by plants (Mitchell and Chandler, 1939).

In addition, the most soluble and available form of nitrop
gen (nitrate) is an anion which is not absorbed by the
negatively charged clay particles of the exchange complex.
Thus it is highly mobile and easily lost. Ammonium nitrogen,
on the other hand, is positively charged and is absorbed by

the soil exchange complex. Ammonium, however, is usually

66

soon changed to nitrate by microbial activity.

Microorganisms affect the supply of available nitrogen
by decomposing fresh organic matter, releasing some of the
nitrogen in less complex forms and temporarily fixing the
rest in their own protoplasm. The proportion of nitrogen
released to that fixed is dependent upon the carbon-nitrogen
ratio of the substrate. A high carbon-nitrogen ratio will
result in the release of little or no nitrogen available to
plants and may even tie up some of the inorganic nitrogen
present.

In addition to their role in constantly changing the
form of soil nitrogen, soil microorganisms are instrumental
in adding nitrogen to the soil through the ability of some
of them to fix atmospheric nitrogen.

All these factors make it extremely difficult to assess
the nitrogen content of the soil by a chemical analysis
(Hunter, 1958). Low total soil nitrogen on a high yielding
site may only reflect a quicker release of organic nitrOgen
to a more available form and its consequently more rapid
absorption by the plants.

Nitrogen is an important factor in the availability of
phosphorus. Even though the nitrate anion competes with
the phosphate anion in the uptake of nutrients by plant
roots, sufficient nitrogen must be present in the soil for
microbial use, in order for the organic phosphorus to be
released from the plant residues. In the present study,
there is a very strong correlation between nitrogen and

phosphorus in the tree leaves as shown by a correlation

67

coefficient of .851. It is probable that the better uptake
of phosphorus by the trees in the area of good growth and
the greater amount of available phosphorus in the soil may
be due, at least in part, to the greater amount of available
nitrogen in that area as indicated by its higher concentra-
tion in the good growth area leaves.

In contrast to total soil nitrogen, phosphorus level_
in the soil has sometimes been found to be correlated with
tree absorption and tree growth (Bsur, 1959: Pawlick and
Arneman, 1961). On this basis, the higher soil phosphorus
in the area of good growth is related to the better tree
growth in that area.

The influence of a lower available water supply in the
area of poor growth as determined by Shipman (1952), on the
uptake of nutrients must be considered. In general, it is
believed that there is an increase in the absorption of
nitrogen with a decrease in soil moisture and there is a
decrease in the absorption of phosphorus and potassium with
decreasing soil moisture (Hibbard and Nour, 1959). Using
1 sand cultures, Kramer and Pharis (1960) found that decreas-
‘ing moisture resulted in an increase of nitrogen in the
leaves. Lundegardh (1945) observed that nutrient concen-
tration in leaves varied according to total precipitation,
and was generally higher in drier years. Acting on these
observations, he initiated a fertilizer and watering exper-
iment and found that nitrogen concentration in the leaves

of test plants was higher at the lower moisture levels.

 

68'

Leyton.(1957a) states that if growth is reduced by moisture
deficiencies and if the deficiency does not interfer with
uptake, leaf concentrations of nutrients should automatically
rise. 0n the basis of these findings, the greater nitrogen
concentration in the leaves of the good growth area compared
to the poor growth area is not related to the soil moisture
supply but is a result of more available nitrogen in the
soil. '

The increase of nitrogen absorption by roots to de-
creasing soil moisture is due to the high solubility of
available nitrogen ions. As the quantity of the soil
solution decreases, the concentration of the available
nitrogen increases, resulting in greater absorption due to
3588 action. On the other hand, phosphorus is relatively

insoluble. Dbcreasing soil moisture causes little or ne
rise in the concentration of this element and a portion
of the total phosphorus is lost from the soil solution
by precipitation. Therefore, there is proportionately
less of this nutrient available in the soil solution for
root absorption.

A dense stand of poverty grass and annual weeds is
found in the area of poor growth due to the lack of crown
closure by the trees (Figs. 5 and 10). These plants may
compete for nutrients and moisture with the trees and may
be a factor in the poor growth in that area. Aird (1956)
concluded from a fertilizer study that weed and grass
competition seriously inhibited the growth of hybrid poplar.
Elimination of the grass and weeds by tillage resulted in

 

.5"

J

.nm>00 mean age Seem happen oasmwue oavuwa hao> spa: nape: use memmmpw
mo pe>oe emcee m macaw seem nuseaw seem as» he commune HHom one u .OH shaman

 

70

significantly better growth both with and without fertili-
zation. Chlorotic leaves of fertilized trees, where the
competing grasses and weeds had not been eliminated, indicate
the intense competition of those plants for nutrients.

It is not known whether there was a difference in the
ground cover between the good and poor growth areas at the
time of planting. If the grass and herb cover on the poor
growth area was significantly more dense at that time, then
that may have been an important factor accounting for the
present size difference of the trees in the two areas. At
the present time, the grasses and herbs are probably re—
moving sizable portions of the water and nutrients that
would otherwise be available for the trees. However,.it is
not known whether they compete to a greater or lesser extent
than the dense undercover of sugar maples and other sapling-

sized trees in the area of good growth.

CHAPTER VIII
CONCLUSIONS

Foliar analysis of yellow-poplar Trees in two parts of

a plantation in southwestern Michigan, indicates that the
growth differential between the two areas is due in part to
differences in nutrient regimes. Significant differences
in nutrient concentration of the leaves between the two
areas of growth suggest that a severe nutrient deficiency
is limiting growth in the poor area.

Tree growth is, to a large extent, a result of the
relative production of phetosynthate. Nutrient deficiencies
seriously limit photosynthesis indirectly through reduction
of leaf size and chlorophyll content (Kramer, 1958). For-
mation of chlorophyll is dependent on adequate supplies of
nitrOgen, magnesium, iron, copper, and zinc. Deficiencies
of any of these nutrients will decrease growth. Kramer
(1958) reports that adding nitrogen to apple trees in the
autumn resulted in better retention of chlorophyll and
higher photosynthetic activity in late autumn. In the
present study area, not only are the leaves in the good
growth area noticeably larger and of a darker green color,

but autumn coloration and leaf fall are delayed several
tweeks as compared to the poor growth area. This in itself
is an indication of a more adequate supply of nitrogen in
the better growing area and results in a longer period of
photosynthetic activity.

Besides reducing photosynthetic activity per unit area

71

72

of leaf surface, deficiency of nitrogen reduces the total
-leaf surface area, and the combined effect of this is a
serious reduction in the amount of carbohydrates available
for growth. In the area of good growth, not only are the
leaf areas on the average greater than in the area of poor
growth, but the tree canopies are more dense, providing
more leaves for photosynthetic activity.

0f the nine nutrients found in significantly smaller
quantities in the leaves of the poor growth area, it appears
that nitrogen and phosphorus are the two most responsible
for limiting growth in that area. The microrelements and
calcium appear to be present in sufficient concentrations
in the leaves of both areas so that they cannot be considered
deficient. The weaker correlation of potassium concentra-
tion in the leaves to height and diameter growth indicates
that this element is probably not a primary reason for the
'growth differential found in the plantatiOn. This is
corroborated by the lack of response to potassium fertilizat-
tien on a nearby yellow-poplar plantationl/. On the other
hand, both nitrOgen and phosphorus leaf concentration were
strongly correlated with height and diameter growth of the
yellow-poplar trees. Comparison with other studies (Mitchell
and Chandler, 1939: Wells, 1961) indicates that nitrogen
is severely deficient in the poor growth area. The lack
of correlation that was found between nitrogen concentration

in the leaves and total soil nitrogen is not uncommon (Bard,

 

1/ white, 0. P., and R. F. Finn 1961. op. cit.

73

1946; Mitchell, 1934).. Possible reasons for this have been
discussed previously. However, soil analysis did show
significantly higher quantities of available phosphorus in
the soil of the good growth area, which agrees with the
higher concentrations of leaf phosphorus found in the trees
from that area. Again, these results are in accord with
other work (Bard, 1946; Baur, 1959).

Findings of White and Finn's experimentl/, reported
earlier, corroborates the conclusions from the present
study, that the depressed growth and vigor of the yellow-
poplar trees on the poor growth area primarily result from
a nutrient deficiency in that area. The correlation between
the increased growth and higher leaf nutrient concentration
of the fertilized trees in the fertilizer study can also be
compared to the larger trees and higher leaf nutrient cone
centration in the good growth area of the present study.

‘It is apparent that the better growth in each instance is
a result of an improved nutrient regime.

In the present study, the question arises as to the
reason for the difference in the nutrient regime of the two
growth areas which have very similiar soils and apparently
identical past treatment. The answer lies, at least in
part, in the annual additions of organic matter deposited-
in the area of good growth (Fig. 9) from the adjacent hard-
wood stand. Mitchell and Finn (1935) Paint out that the

principal means by which trees may improve the chemical

 

;/ White, 0. P., and a. r. Finn 1961. op. cit.

74

fertility of the soil is through the annual addition of
mineral nutrients and nitrogenous material contained in the
leaves.

Data gathered here show that the yearly deposit of
tree litter in the area of good growth is far greater than
that deposited in the area of poor growth. Much of the
extra deposit consists of material from outside the plants-
tion. The litter on the good growth area has higher con-
centratiens of nitrogen, phosphorus, and potassium than the
litter on the poor growth area. This, coupled with the
greater quantity deposited in the good growth area, results
in considerably more of these nutrients being added there
to the nutrient regime each year. In essence, it amounts
to an annual program of fertilizer application for the
promotion of better growth.

In the previous examination of the study area, Shipman
(1952) found certain microclimatic differences between the
two areas of growth that might produce a less favorable
water balance between uptake and transpiration losses in
the area of poor growth as compared to the area of good
growth. These microclimatic differences are the result of
the fringe influence of the old-growth hardwood stand at
the south and west edges of the good growth area. It
resulted in lower air temperatures and higher relative
humidities in that area.

Both of these factors result in relatively more rapid
transpiration losses in the poor growth area as opposed to

the good growth area, causing possibly more frequent and

 

75

longer periods of water deficits in the leaves of the poorer
trees. This in turn would reduce photosynthesis by restrict-
ing the entrance of carbon dioxide into the leaves because
of stomate closure. This condition is aggravated by the
lower amount of water available on the poor growth area
because of weed and grass competition. Kozlowski (1958)
points out that water deficits develop regularly in leaves
during the middle of the day and cause a decrease in photo-
synthesis even when the soil is adequately supplied with
water. Kramer (1958) also states that bright sunlight and
dry air causing excessive transpiration produce water
deficits in the leaves of trees growing in moist soil.

Shipman (1952) concluded that available moisture was
the primary factor limiting the growth of yellow-poplar due
to less favorable microclimatic conditions in the poor
growth area. This reasoning was based partially on the
significantly shorter supply of water in the soil at 6 and
18 inches on the poor growth area. However, it should be
pointed out that the available moisture did not fall below
70 percent at the 6-inch depth or 80 percent at the 18-inch
depth during the 1951 season. During the 1952 season, the
available moisture in the poor growth area did not fall
below 50 percent at the 6~inch depth, except for a 6-day
period in early July, and was significantly higher in the
poor growth area compared to-the good growth area at the
18-inch depth.

Soil moisture is probably about equally available

throughout the range from field capacity to wilting point

76

in a sandy loam soil (Army and Kozlewski, 1951; Kramer,
1949). Certainly there should not be any difficulty in
.water absorption by the yellow-poplar roots above 50 percent
available moisture in the coarse soil of the study area.

The greater amount of nitrogen available for tree
growth in the good area is probably a factor in the better
uptake of other nutrients. When nitrogen is deficient, the
physiological processes of the tree are interrupted, in-
cluding active nutrient absorption. The greater amount of
nitrogen supplied to the good growth area from the litter
of the adjacent hardwood stand results in more vigorous
root growth. This in turn enables those trees to exploit
more of the soil for both moisture and nutrients. Stone
et a1. (1958) found with red pine in New'York State that
adequate nutrients may promote root growth in xeric condi-
tions of deep sandy soils so that the trees may exploit
greater volumes of the soil for moisture. White (1958a)
reports that fertilizer applications resulted in an increase
in photosynthetic activity and water economy during a period
of moisture stress.

The results of this study and Shipman's (1952) previous
work on the same plantation, supported by similiar results
from other studies, show the growth differential exhibited
in two parts of the yellow-poplar plantation is due primarily
to two factors. One, the nutrient regime of the good growth
areais much more favorable due to annual additions of
nutrients from the litter deposited from the adjoining old-
grewth mixed hardwood stand; two, the less favorable micro-

77

climate in the area of peer growth may be limiting growth
by causing water deficits in the tree leaves from more
rapid transpiration losses than the trees are able to
overcome by absorption of water from the soil.

whether these two factors are equal in their effect or
one is more dominant cannot be said with certainy at this
time. However, the fertilizer study;/, previously mentioned,

increased growth without changing the microclimate.

 

_1_/ white, D. P., and R. F. Finn 1961. op. cit.

CHAPTER IX
SUMMARY

Yellow-poplar (Liriodendron tulipifera L.) is an impor-
tant tree in the central hardwood region. This species
makes good growth in southwest Michigan, at the northern
edge of its natural range. It grows rapidly on good sites,
develops very good form, and is relatively free from insect
and disease attacks. Normally, it is not abundant in
natural stands, but because of its desirable characteristics.
it is widely planted throughout its range.

Trees in two parts of a 33-year-old plantation of
yellow-poplar in southwestern Michigan show striking differ-
ential height and diameter growth. Because of the limited
area in which this growth difference occurs, and because
(the entire plantation was established the same year, from
the same planting stock under apparently identical planting
conditions, this plantation offers an excellent opportunity
to study the site factors which contribute to the growth of
this species.

A detailed edaphic, microclimatic, and microbiological
investigation of this plantation was initiated by Shipman
(1952) in 1951. The conclusions from his study were that
the growth differential resulted from a combination of micro-
climatic conditions that produced a more favorable moisture
regime in the area that had the best growth, and that no
nutrient differences existed between the two areas.

In the present study, observation of the foliage

78

 

79

suggested that a nutrient difference between the two areas
does exist. The leaves on the good growth area are larger
and consistently of a darker, healthier, green color. By
contrast, the leaves in the poor growth area show character-
istics indicative of a nutrient deficiency. Using modern
methods of foliar analysis, including spectroscopy, this
study was made to determine if nutrient differences exist
between the two areas.

The sample trees in the good growth area averaged 57.5
feet in height as opposed to an average of 26.6 feet in the
area of poor growth. Diameters were also larger, averaging
7.38 inches in the better area compared to 3.99 inches in
the poorer area. An analysis of the foliage from both areas
showed that the area of good growth had significantly higher,
at the one percent level, concentrations of all the macro-
elements, except magnesium, and most of the micro-elements
in the leaf tissue. Nitrogen composition averaged 1.75
percent of dry leaf weight in the good growth area and 0.95
percent in the poor growth area. Phosphorus levels averaged
0.196 percent of dry leaf weight from the better growing
trees and 0.101 percent in the leaves of the poorer growing
trees. These concentrations show that the yellow-poplar in
the poor growth area are severely deficient in nitrogen and
phosphorus.

A statistical comparison of both height and diameter
growth of the yellow-poplar sample trees and the nutrient
composition of their leaves revealed a highly significant

correlation between the nutrient concentration of eight of

80

the elements in the leaves and both height and diameter of
the trees. Nitrogen and phosphorus showed particularly
strong correlations between nutrient cencentration and
height growth. From these data, supported by other published
studies and corroborated by unpublished data;/ from a

nearby fertilizer study, it is concluded that nitrogen and
phosphorus are two of the primary factors contributing to

the differential height growth of the planted yellow-poplar.
Foliar analysis of the yellow-poplar trees showed that

the soil nutrient regime is more favorable in the area of
good growth than in the area of poor growth. Much of this
difference can be attributed to the nearly three times as
great a quantity of litter being deposited on the area of
good growth each year compared to the area of poor growth.
Much of this additional litter comes from an adjoining oldé
growth mixed hardwood stand to the south and west of the
good growth area. In addition, the nutrient composition
of the litter on the good growth area is in most cases
slightly higher, resulting in considerably greater quantities
(statistically significant at the one percent level for six
nutrients) of plant nutrients being added to that area each
year. This litter is probably the primary source of most
of the nitrogen and phosphorus available for tree growth.

A factor that may contribute to the growth differences
in the two areas, is the dense stand of grasses and herbs

found in the poor growth area but not in the good growth

:7 HhIte, D. P., and R. F. Finn 1961. op. cit.

 

81

area. This ground cover may compete for soil nutrients and
moisture to a great extent. It is not known how serious
this competition may be, or whether it is greater or lesser
than the competition from the dense undercover of sugar
maple and other saplings found in the good growth area, but
to a much lesser extent in the poor growth area.

It is concluded from the data collected in this study
.that the significantly better growth of the trees in the
good growth area results in a large part from the better
nutrient regime there. Trees from the poor growth area are
decidedly deficient in nitrogen and phosphorus. The better
nutrient regime of the good growth area stems from deposits
of litter from the adjoining old-growth hardwood stand.

In addition, Shipman's (1952) study showed that the micro-
climatic conditions in the area of poor growth are less
favorable, which may result in longer periods in which

water deficits in the leaves halt photosynthesis.

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, and N. S. Bayliss
9 . e necessity of zinc for Pinus radiata. Plant
Phys. 17: 303-310.

Smith, N. F.
1961. Michigan trees worth knowing. For. Div., Mich.
Dept. of Cons., unnumbered publ. 59 pp.

Society of American Foresters, Committee on Forest Terminology
1958. Forest Terminolo . Soc. Amer. For., Washington,
DT‘CT‘ 38. Ed. rev. 93 pp.

Stone E. L. 4
1958. A look ahead at forest fertilization research.

Better Crops With Plant Food 42: 45-54.

I955. Magnesium deficiency of some northeastern pines.
Soil Sci. Proc. 17: 297-300. a .

, G. Taylor, N. Richards, and J. Dement
I958. 8011 and species adaptations: red pine plantations
in New York. Proc First N. Amer. For. Soils Conf.,
Mich. State Univ., Agric. Expt. Sta., East Lansing.
pp. 181-184. .

Swan, He Se De
1960. The mineral nutrition of Canadian pulpwood species.
Pulp and Paper Res. Inst. of Canada Tech. Report
168. 66 pp. '

Thompson, L. M.
1957. Soils and Soil Fertility. McGraw-Hill Co., New
York. 451 pp.

U. 8. Forest Service 7
1948. Wood -P1ant Seed.Manua1. U.S}D.A. Misc. Publ. 654.
8.8. 8075. Prlnt. CTT., Washington, D. C., 416 pp.

87

Voigt, G. K.
1958. Plant-soil factors in chemical soil analysis.
Proc. First N. Amer. For. Soils Conf., Mich. State
Univ., Agric. Expt. Sta., East Lansing.. pp. 31-41.

Walker, L. C.
1956. Foliage symptoms as indicators of potassium-defi-
cient soils. For. Sci. 2: 113-120.

1953. Foliar analysis as a method of indicating potass-
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degree of Ph.D., Colle e of For., State Univ. of
New York at Syracuse, Unpublished) 182 pp.

Wells, Ce Gs
1961. Underplanting tests in pine stands. S. E. For.
Expt. Sta. Res. Note 160. 2 pp.

White, De Pe
1958a. Available water: the key to forest site evaluation.
Proc. First N. Amer. Forest Soils Conf., Mich.
Stat; Univ., Agric. Expt. Sta., East Lansing.
pp. -11.

I9585. Forest research studies plant food usage. Better
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Agric. Expt. Sta., East Lansing. pp. 49-52.

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, and A. L. Leaf
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1958a. Diagnosis of nutrient deficiencies by foliar and
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88

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APPENDIX

APPENDIX”A
STUDY AREA SOIL DESCRIPTIONS

Fox sandy loam (acid variant)

Soil profile:

Ap 0-8"
A2 8-12"
31 12-15"
321 16-32"
322 32-35"
D 36"+

Dark grayish brown to brown: sandy loam; weak,
medium, granular structure; friable; pH = 5.2.

Brown: sandy loam: weak, coarse, granular struc-
ture: friable: medium acid.

Dark yellowish-brown to dark brown: sandy loan to
silt loam: moderate, medium, subangular blocky
structure; firm; medium acid.

Dark brown to dark reddish brown; sandy clay loam;
moderate, medium, subangular blocky structure:
firm to very firm; IH :: 4.9.

Dark brown to dark reddish brown; gravelly clay
loam; weak, coarse, subangular blocky structure:
firm when moist and slightly plastic when wet:
slightly acid.

Pale brown or brown: stratified gravel and sand;
single grain structure; loose; calcareous.

On the study area, the Fox sandy loam is a well-drained
Gray-Brown Podzolic soil, occurring on a nearly level outwash
plain with numerous shallow depressions. It originally
supported a mixed hardwood type of vegetation.

Warsaw sandy loam (acid variant)

Soil profile:

AP 0-8"
A12 8-12”
821 12-16"
322 16-32"

323 32-35"

Dark grayish brown; sandy loam: weak, medium,
granular structure; friable; pH = 5.2.

Dark grayish brown: sandy loam: coarse, granular
structure: friable: medium acid.

Dark brown; sandy loam; moderate, fine, subangular
blocky structure; firm; medium acid.

Dark reddish brown: sandy clay loam; moderate,
medium, subangular blocky structure; pH = 4.9.

Dark reddish brown; sandy clay loam; weak to
90

91

Warsaw sandy loam (acid variant) cont.

moderate, coarse, angular to subangular blocky
structure; firm when moist, plastic when wet,
and hard when dry; slightly acid.

D 36"+ Light brownish gray or pale brown; gravel and
- sand; stratified; loose; calcareous.

On the study area, Warsaw sandy loam is a well-drained
Brunizem soil, occurring on an outwash plain dotted with
shallow depressions. It originally supported a tall prairie
grass type of vegetation.

APPENDIX B
LEAF AND LITTER ANALYSES PROCEDURES

Microkjeldahl procedure

Fifty to 80 milligrams of oven-dried leaf material is
weighed to four places of accuracy on a "Mettler" B-S ana-
lytical balance and placed in a microkjeldahl flask. A
micro-spatula of dry mixture, consisting of one part of
potassium sulphate and three parts of mercuric sulphate, is
added to the plant material, along with one cc. of digestion
reagentl/. The mixture is then digested over heat, under a
hood, until a water-clear solution is obtained. The diges-

tion process takes-approximately two and one-half hours.

A small quantity of distilled water is added to the solution
to dissolve the precipitated salts and the material is then
ready for distillation.

, After the solution is introduced into the distillation
apparatus, five cc. of oily lye (concentrated sodium hydrox-
ide) is added and the material distilled into an Erlenmeyer
flask containing ten cc. of 1.5 percent boric acid and two
drops of brom cresol green-methyl.red indicator. The distil-
late is titrated with standardized .01 normal hydrochloric‘
acid and the quantity of nitrOgen calculated.

This process is a wet combustion method of digestion

in which the fate and carbohydrates of the leaf material are

 

1/ Prepared by adding 1 gram of salicylic acid to 30 cc. of
sulphuric acid. ’

92

93

oxidized into carbon dioxide and then volatilized. The dry
mixture added to the plant material is a source of oxygen,
acts as an oxidizing agent, and raises the boiling point of
the water. The proteins are hydrolized into amino acids and
the carbon, hydrogen, and oxygen converted into carbon dioxide
and water. The nitrogen is liberated as ammonia and immedi-
ately converted into ammonium sulphate by the excess of
sulphuric acid used in the oxidation. After oxidation, the
ammonia is released from its salt by adding an excess of
sodium hydroxide and collected in the boric acid solution.

The amount of ammonia liberated is determined by titrating
the boric acid-ammonia solution with standardized hydrochloric

acid and the amount of nitrOgen computed from these data.

Elggg photometer procedure

Approximately 0.2 grams of leaf material is weighed to
the nearest milligram and placed in an Erlenmeyer flask
Fifty m1. of 1.0 normal ammonium acetate is added, the
mixture is shaken intermittently for thirty minutes, and is
then filtered into a clean beaker. The filtrate, containing
the extracted potassium, is introduced into the flame photo-
meter and oxidized by means of a high intensity, direct
atomizing, oxygen-gas burner. The light from the burning
filtrate is picked up by a vacuum phototube after passing
through a light filter that removes all of the spectrum
except that part from the oxidizing potassium. Electric
current generated by the phototube is transmitted to a

galvonometer where it is read on a scale from O to 100.

94

Ppm. of potassium is found on a calibration curve previously
prepared by oxidizing a range of solutions of known potass-‘

. ium concentrations.

Photoelectric spectrometer procedure

 

Leaf analysis for phosphorus, calcium, magnesium, iron,
manganese, copper, boron, zinc, and molybdenum was made by
a TQuantograph“;/ photoelectric spectrometer operated by the
Department of Horticulture, Michigan State University. Leaf
ash is burned by means of an interrupted electric arc, pro-
ducing a spark-like condition. The desired wave length of
each element is passed through a slit and the light received
by a specific phototube positioned behind the slit.. The
light energy is changed to electric energy by the phototube
and recorded on a chart. Readings from the chart are trans-
formed to quantity of the particular element from tables
prepared during the calibration of the instrument.

The sample is prepared by ashing a 0.5 gram quantity of
oven-dried leaf material for 12 hours at 550 degrees C. The
leaf ash is dissolved in the ash crucible with 5.0 m1. of
hydrochloric acid-cobalt-lithium-potassium solution. A
portion of the dissolved ash is transfered to a porcelain

_ boat and burned in the spectrometer.

;/ Produced by Applied Research Laboratories, Inc., Glendaleo
California.

APPENDIX C

COEFFICIENTS OF CORRELATION

FOR COMBINATIONS OF TREE HElch,
TREE DIAMETER, AND NUTRIENT .

ELEMENT COMPOSITION OF LEAVES--

 

Hts

Dia.

Hts +1.00“ +Os919

N

+Os758

K

+0 .297

.3.
+0s764

Ca
+Os466

 

.38.
+0.26)

 

Ht.
Dia.

Dia.

+1.000

+0s647

+0.150

+0s684

+0.43}

+0s193

‘—

 

-c-OI-J

Vr
s 1

 

+0.47?
+0.41?

N‘

+1.000

+0s492

+0.851

+0s264

+Os123

 

Fe

 

+0.551
+0.342

K

+1.000

+0.486

“OeOAS

~0s173

 

Cu

 

+0.546
+0s413

P

+1.000

+0.404

+Cs259

 

B

+0.066
+Os107

Ca

+1.000

+0030?

 

Zn

 

+Os4h7
+0.275

._l' “a“ 1‘“"

Ms

+1.000

 

Mo

 

+Os371
+Os336

A1

-0s125

'“Os162

 

+0.389
+Os084

+0.620
+0.529

+0.71?
+Os478

-0s145
-0s426

+0s419
+Os425

+0s255

-0.002

'0s205
_0s142

 

+09465

+0.561

+Os666

'0s046

+0.4l9

+00316

-0s170

 

Ca
Ms
Mn

+0.169

+Os375
+1sOOO

+Os264

'+o.092

+0.3l2

+Os206
+0.086
+Os291

+0s275
+Os367
+0s198

+09335
+0.195

+0.218

+0.833
+0.316
+0.112

-0.081
+0s256
+Os188

 

Fe

+1.000

+0s713

’OsOSI

+Os610

+0.264

+0.058

 

Cu

+1.000

-0.080

+0.50?

+0.25}

-0s102

 

B

+1.000

“09088

+Os231

+0.344

 

Zn

+1.000

+Os3h0

~0.132

 

MO

+1.000

-C.O75

 

Al

+1s000

 

1/ For 62 degrees of freedom; a correlation.coefficient of
0.320 or larger is significant at the 1 percent level,
0.246 or larger is significant at the 5 percent level.

95

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