EFFECT OF SIZE AREA OPEN. TO
COLONIZATION 0N. SPECIES COMPOSITION
III EARLY OLD-FIELD SUCCESSION

' Thesis for the Degree of M. S.
MICHIGAN STATE UNIVERSITY
ROGER M. DAVIS
1968

 

 

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ABSTRACT
EFFECT OF SIZE AREA OPEN TO COLONIZATION ON

SPECIES COMPOSITION IN EARLY OLD-FIELD
SUCCESSION

{5

by Roger Mlfigavis

This study deals with the effect of size of an area
open to colonization in early old—field succession in south-
western Michigan. The prime questions of the study are what
effect does Opening size (or size of the area available for
colonization) have in determining the Species present in
the Openings and how does the existing undisturbed vegeta-
tion affect future stages in the succession?

The study was carried out in a newly abandoned field
on the Gull Lake Biological Laboratory property in Kalamazoo
County, Michigan. The field had been planted to corn in
1964 and abandoned after the fall harvest. In June 1965
Openings ranging in size from .Olmz-lOOm2 were dug or plowedt
into the existing undisturbed fallow vegetation. The open-
ings were then sampled in August 1965, June and August 1966,
and June 1967. Per cent cover values by species for each

1

Roger M. Davis

opening were obtained. In addition 0.5m x 2m quadrats of
the undisturbed fallow vegetation were sampled in the same
manner.

The course of succession was found to be slightly
different in the Openings as compared with the undisturbed
vegetation. Smaller openings were more like the undis-
turbed vegetation than the larger Openings in the first
year, but this difference gradually declined in succeeding
seasons.

The per cent cover of 14 of the 77 species found
appeared to be correlated with the size of the opening.
The most striking effect was noted in Amaranthus retro-
flexus which was significantly positively correlated with

increasing opening size. The size of Amaranthus plants

 

also showed an increase with increasing opening size. The
majority of the 14 species showing correlations with open-
ing size were positively correlated with increasing opening
size though several negative correlations occurred.

These studies suggest that opening sizes smaller
than 100 cm2 would be best for examining various mechanisms
Operating in producing the organization that develOps with

the successional process.

Roger M. Davis

For the range of sizes used, evidence indicates
that the Opening does not affect the later pattern of suc-
cession by altering Species composition, nor does it seem
that the initial dominant annuals have a determining in-
fluence on the later pattern of succession, at least for

the dominants found here.

EFFECT OF SIZE AREA OPEN TO COLONIZATION ON
SPECIES COMPOSITION IN EARLY OLD-FIELD

SUCCESSION

BY

.I
.Lyxa‘b'

Roger MJ Davis

A THESIS

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

MASTER OF SCIENCE

Department of Botany and Plant Pathology

1968

ACKNOWLEDGMENTS

I wish to thank my major professor, Dr. John E.
Cantlon, for his generous aid and supervision in both my
scholastic and research program. I wish to thank the
other members of my committee, namely Dr. John Beaman and
Dr. Clifford Pollard, for their critical review of this
manuscript.

I am grateful to Dr. George Lauf, Director of the
W. K. Kellogg Gull Lake Biological Station, and Mr. Harold
Webster, farm manager, for providing the area for this
study and for their aid in the actual mechanics of the
study.

I wish to thank my colleague Mr. Buford Holt for
his constant aid during this study and also Mrs. Carol
Thomas, computor programmer, without whose aid the statis-
tical analyses would have been a great burden.

This study was supported by funds made available

by the National Science Foundation (Grant GB 1220).

ii

TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS. . . . . . . . . . . . . . o . . . . ii
LIST OF FIGURES. . . . . . . . . . . . . . . . . . . V

LIST OF TABLES . . . . . . . . . . . . . . . . . . . Vi

Chapter
I. INTRODUCTION . . . . . . . . . . . . . . . . 1
II. LITERATURE REVIEW. . . o . . . . . . . . . . 5
A. General Trends in Succession . . . . . . 5
B. Factors Involved in Succession . . . . . 7

C. Michigan Studies . . . . . . . . . . . . 14

III. DESCRIPTION OF AREA. . . . . . . . . . . . . 17
IV. METHODS. . . . . . . . . . . . . . . . . . . 22
V. RESULTS. . . . . . . . . . . . . . . . . . . 25
A. Pattern of Succession. . . . . . . . . . 25

B. Opening Size . . . . . . . . . . . . . . 31

C. Opening Size and Community Composition . 38

D. Effect of Initial Species. . . . . . . . 40

iii

Table of Contents-~Continued

Chapter Page

VI. DISCUSSION . . . . . . . . . . . . . . . . . 41

VII. SUMMARY AND CONCLUSIONS. . . . . . . . . . . 53

LITERATURE CITED. . . . . . . . . . . . . . . . . . . 58

APPENDICES. . . . . . . . . . . . . . . . . . . . . . 62
APPENDIX A . . . . . . . . . . . . . . . 63
APPENDIX B . . . . . . . . . . . . . . . 67

APPENDIX C . . . . . . . . . . . . . . . 96

iv

LIST OF FIGURES

Page
Photograph of study area in July 1965 . . . . l9
Plot map of study area and weed treatments. . 21

Change in average per cent cover of several
species with time for undisturbed fallow
plots. . . . . . . . . . . . . . . . . . . 28

Change in average per cent cover of several
species with time for undisturbed fallow
plots. . . . . . . . . . . . . . . . . . . 29

Average per cent cover vs. Opening size for
several Species in August 1965 . . . . . . 33

Average per cent cover vs. Opening size for
several species in June 1966 . . . . . . . 34

Average per cent cover vs. Opening size for
several Species in June 1966 . . . . . . . 35

Average per cent cover vs. Opening Size for
several species in August 1966 . . . . . . 36

Average per cent cover VS. opening Size for
several Species in June 1967 . . . . . . . 37

LIST OF TABLES

Table Page

I. List of opening sizes and numbers . . . . . . 23

II. Presence list of species found in study area
in 1966 or 1967. . . . . . . . . . . . . . 26

III. Species appearing in 1965 but not in 1966 or
1967 . . . . . . . . . . . . . . . . . . . 30

IV. Coefficients of Similarity between vegetation
develOping in openings of various Sizes. . 39

vi

EFFECT OF SIZE AREA OPEN TO COLONIZATION ON
SPECIES COMPOSITION IN EARLY OLD-FIELD
SUCCESSION

I. INTRODUCTION

Succession as described by Margalef (1963) is the
process of the community's becoming more precisely adjusted
to its environment. Viewed from another perspective, it is
the process by which the species of a regional biota colo-
nize and hold their niches against their competitors. Sev-
eral generation times of the later, long-lived, species
populations are necessary to stabilize the system. This
process is one of fundamental importance in ecology in par-
ticular, and in biology in general. On any particular Site
if the biological properties of the ecosystem are disturbed
(e.g. by clearing, fire, etc.), the process of succession
is represented by the sequence of pOpulations that succes-
sively occupy the site before the biological array returns
to approximately the predisturbance composition. This tend—
ency for complex species arrays to return to a relatively
predictable composition is an expression of homeostasis.

l

Not only does a displaced stable biological array tend to
return to its original composition but, large enough sub-
samples of the array examined at the same time on the same
homogenous Site tend to follow Similar paths at similar
rates. The principle of predictable successional sequences
is unique to ecology and of fundamental importance to bi-
ology. AS such it warrants study.

What are the mechanisms involved in the gradual
change of terrestrial plant communities from one array of
Species to another, for example, the change of an abandoned
cornfield from its initial array of the crop plus a few
weed Species to the different arrays found one, two, five,
or ten years later? Change comes about as the result of
the successful invasion of new species, the inability of
species already present to persist, and changes in the pro—
portion of the total universe that each established Species
pOpulation occupies. Does, and if so how does, the Species
array present at a given time influence or to some measure
control the order of future arrays? What effect does the
initial vegetation in a succession have on determining the
future couse of that succession? Knowledge about the es-
tablishment and survival of new species is crucial to an-

swering these questions.

Clements as early as 1916 recognized the importance
of bare areas in the process of succession. He states that
"Seres originate only in bare areas or in areas in which
the original pOpulation is destroyed" (Clements, 1916).
Milthorpe (1961) more Specifically states that "establish-
ment of plants from seed in vegetation occurs only in 'bare
areas' arising from the death of previous occupants or from
incomplete coverage." Harper §t_al, (1965) have shown that
for many species, germination success is highly sensitive
to microsite. Cavers and Harper (1967) have Shown that
even for Species whose seeds germinate freely in almost any
situation, seedling survivorship is quite microsite—related.
Studies carried out by Caruso (1963) suggested the size of
an Opening created in an established vegetation had an ef-
fect on the survival and reproduction of certain species.
He cut holes ranging from 0.5 to 3cm in diameter in old-
field grown bluegrass sod transferred to pots in the green-
house. Seeds of various plants were then sown in the Open-
ings. Caruso found that survival but not germination of

Melilotus sp. seeds was significantly positively correlated

 

with the Size of the Opening. Positive correlations with

other Species could not be established but indications were

that germination of Solidagp canadensis, Aster pilosus, and

Monarda fistulosa was affected by the size of the Opening.

 

Thus a number of workers have indicated that the existing
vegetation influences the probability of establishment of
later immigrating species, and Caruso has shown that the
Opening sizes in an existing vegetation can also influence
establishment probabilities of later immigrants.

The present study was made in an attempt to inves-
tigate the effect of Opening size under field conditions
using larger openings than Caruso. The prime question of
the study then is what effect does Opening size (or the
size of the area available for colonization) have on de—
termining the species present in the area and does the

existing vegetation affect future stages in the succession?

II. LITERATURE REVIEW

A. General Trends in Succession

 

Succession has long been recognized as a funda-
mental process in the history of ecology. As early as
1916 Clements had written a large volume on the subject
in which he reviewed earlier work, some of which was
written nearly two hundred years ago (Clements 1916).
Though recognized as a process fairly early, detailed
population studies of particular successions and succes—
sion in general are quite recent. At present our under-
standing of the successional process is quite limited.
Margalef (1963) states a number of axioms which summarize
our knowledge of the trends in succession. Some of the
axioms are accepted as eXperimentally confirmed while the
validity of others remains untested. In succession there
seems to be an increase in species having the ability to
accumulate and hold biogenetic elements (biological ma-
terials and genetic information) and an increase in total
standingstock in productivity terms. In addition it seems

5

that the ratio of photosynthetic pigment weight (chloro-
phyl) to total weight drops steadily as succession proceeds.
There is an increase then a leveling of biological diver-
sity. There is an increase in order (predictability). Suc-
cession seems to progress toward conservation of maximum
biomass with minimum relative energy dissipation and toward
increased stability. There is an increase of overall in-
formation stored chiefly in a level where its preservation
is thermodynamically most efficient, and an increase in ef—
ficiency of basic processes. Lastly there is an increase
in heterogeneity, and a progress from unorganized to orga-
nized heterogeneity.

From an evolutionary point of view Woodwell (1965)
adds the following nuances to the above trends. Evolution
and succession tend to proceed toward the reduction of com—
petition; toward the greater utilization of space and other
resources. This is associated with increasing variability
and greater diversity in form and function resulting in the
filling of more niches. Similar environments tend to sup-
port organisms which are Similar in form and function if
not in species. There is an increase in stability. There
is an increase in total photosynthesis and respiration and

an increase in total water use.

The trends outlined in the preceeding paragraphs,
by no means all experimentally confirmed, are the result
of fairly recent investigation. Until recently descriptive
work on succession has been the predominant type of study
of the process. Limnologists and marine biologists have
taken the lead in detailed investigations of succession as
seen in the studies cited by Margalef (1963). Within the
last decade, ecologists concerned with vascular plant have
begun to delve,in a more rigorous manner, into the causes
or mechanisms Operative in the process of succession.

Succession is seen as a directional change in the
dominance hierarchy of species present in a given area
through time (Whittaker, 1963, Numata and Yamai, 1955).
What causes changes in the hierarchy, or more fundamentally,
what factors influence the change in a plant's importance

in a given area over a given time?

B. Factors Involved in Succession

There seems to be three major factors affecting the
presence of a plant at any particular point in a succession:

the availability of propagules; the availability of an

occupiable microenvironment; and the effect of other organ-
isms. Changes in, and interactions among, these factors
produce the particular series of events the aggregate of
which we witness as succession.

The available propagules represent the basic infor-
mation out of which the process of succession molds the
changing arrays. These propagules may be visualized as be-
ing in two categories: those already present on the Site
at the initiation of succession (initial inocculum) and
those immigrating to the Site after succession has begun
(Egler, 1954). The available propagule factor has been the
subject of a fair amount of study. Its Species make-up de-
pends on what plants are within seed dispersal distances,
the cultivation practices prior to abandonment of land,
the last crop, seed content of the soil at abandonment, and
the viability of the seeds in the soil. The soil acts as
a seed bank maintaining a supply of seeds available for
germination under the proper conditions (the concept of
initial floristics of Egler, 1954). The composition of
this soil seed bank determines to a great extent the Species
composition of the initial stages of succession and to a

lesser extent affects later stages.

Early studies such as those of Beal (1905, 1911),
Darlington (1951), and Goss (1924) investigated the via—
bility of seeds buried for various periods of time. These
studies showed that some weed seeds have long viability.
Many were still viable after being buried for the twenty
years in the Goss study while Darlington found several
Species buried by Beal germinated after seventy years.
Brenchley and Warington (1930, 1936) have studied the weed
seed pOpulations of some British soils and discovered that
most seeds have a natural period of dormancy which may last
up to nine years. There also appeared to be a relation be-
tween the type of manuring and the weed flora as a result
of the seed content of the manure.

Costing (1940) studied the viability of seeds in
forest and field soils of various ages. The highest num-
ber of individual plants germinating from soil samples
placed in the greenhouse were in fields abandoned one year
while the highest number of species occurred in.samples <xf
five year old fields. Some species have poor longevity as
shown by lack of germination from soils taken from fields
in later successional stages. Germination of seeds of

several species in soil from habitats in which parents are

10

not found indicates the possibility that seeds may lie
buried for long periods and retain their viability. Odum
(1965) in northern Europe has Shown that some seeds ap—
parently can remain viable under proper conditions for 100-

600 years. Seeds of Chenopodium album and Spergia arvensis

 

 

were found viable in archeological Sites that appear to be
1700 years old. The soil seed bank extends to a fairly
great depth. Robinson and Kust (1962) have shown that
witchweed seed may move to a depth of Sixty inches in
deeply cracking, fine textured tropical soils, indicating
that all seed is not stored near the surface. Seeds stored
at depth do not germinate until some event brings them to
the surface (Odum, 1965).

The soil seed bank, thus, may be a fairly extensive
layer composed of the seed accumulation of many years though
it would seem that the most recent accumulation would be
of more importance in the early stages of succession on fal-
lowed crop land.

One of the selective forces Operating on the sur—
face seed pool which is a determining factor in species
composition at a given stage of succession is the availa-

bility of suitable micro-environments. According to Harper

11

25 a1. (1965) the varied micro—environments provided on a
soil surface act selectively on mixed seed pOpulationS and
determine the numbers of effective germination sites. This
was shown on artificially created soil surfaces of varied
microtopography. Harper and Benton (1966) showed that ger-
mination of seeds was sensitive to water tension applied to
the soil. The area of contact made between seed and sub-
strate and the degree of exposure of seed to the atmosphere
would both affect the seed's moisture relationship, thus
seed Size and establishment probability of plants from seed
may be correlated under natural conditions. Small seeds
ought to be less likely to suffer desiccation and in gen-
eral, seeds of Open habitat plants tend to be smaller than
those of closed habitats (Salisbury, 1942). Large seeded
plants may be at a disadvantage in Open habitats.

Thus, the micro-environment acts to screen the
propagules allowing selective survivorship which in turn
influence the species composition at a given stage.

Changes in the variety of available microenvironments
either through physical or biological action is a major
factor in determining the species present and their posi-

tion in the hierarchy at any given time. Tied in with the

12

microenvironment is the overall climatic factor which has

a long-term effect on the direction of succession in addi-
tion to affecting the course of succession in any particular
year through action on germination, survival, and seed pro—
duction of the Species present (Bormann, 1953).

In addition, Rice 3; a1, (1960) have indicated that
available nutrients at a site and changes in nutrient avail-
ability influence survival and establishment probabilities
of certain seedlings. We thus have yet another screening
factor acting on the available propagule source and deter-
mining the course of succession.

Other variables influencing establishment of old-
field species have also been studied. Clements (1916, 1928)
and Keever (1950) both indicate the importance of seed
source and dissemination capabilities of plants as factors
influencing composition of early successional stages. Kee-
ver (1950) and Rice gt_§1, (1960) indicate that some species
affect the germination and establishment of others and thus
were important in influencing the pattern a given succession
takes.

Keever (1950) in investigating mechanisms in early

succession on the Piedmont of North Carolina found that both

13

the timing of the seasonal cycle of individual Species and
the interactions between species were factors in determin—
ing the pattern of succession there. The life cycles of
the particular Species influences the times at which their
propagules are present, when they germinate, and when
their peak biomass contribution to the succession occurs.
There are other approaches which have contributed
to our understanding Of the phenomenon of succession which
I will mention only briefly. One is the studies of energy
content and flow through communities in various stages of
succession, as exemplified by the work of Odum and his col-
leagues (e.g. Odum 1960, Odum gt 31. 1962, Golley 1960,
Golley 1965). Another approach is the study of pattern in
various stages of succession (e.g. Kershaw, 1963). Lastly
are the effects of various pesticides such as herbicides
and insecticides on the sequences (Woodford and Evans, 1963).
As noted above, much of the work done on succession
to date has been of a descriptive nature. Much of this de-
scriptive work has, for various reasons, been done on the
Piedmont of the eastern United States (Oosting, 1942, Bil-
lings, 1938). One of the more recent is that of Bard (1952)

on succession on abandoned farmland in the Piedmont in New

14

Jersey. She describes a pattern of first year dominance

by annuals such as Ambrosia sp. and Oenothera sp. followed

 

in succeeding years by dominance of perennials such as S9—
lidago spp., Aster spp., and Agropyron repens which may
remain important for more than 45 years. Juniperus vir-
giniana invades in the first few years and becomes the dom-
inant arborescent layer for the nest Sixty years. guercus
spp. and Cary; spp. are well established in the understory
by the sixtieth year. gpbug spp. and Rhus radicans are the
dominant shrubs after 25 years. Within limits the pattern
is predictable, indicating the operation of particular pro-

cesses .

C. Michigan Studies

Relatively little work has been done on old-field
succession in Michigan. Dice (1931) presented a prelimi-
nary classification of the major terrestrial ecologic com-
munities in Michigan and in it included old-field types.
Beckwith (1954) described the general pattern of succes—
sion on abandoned farm land in Michigan after various cul-

tivation practices, e.g. annual crOps, small grains, hay,

15

etc. He also estimated the rates of invasion of woody
plants. In general, the successional sequence he pictured
starts with weedy annuals which are of different species
depending on time of year the last disturbance occurred
and pre—abandonment management practices, followed by a
perennial grass stage which is followed in turn by woody
plant invasion.

Evans and Cain (1952), Cain and Evans (1952),
Clark and Evans (1954), Evans and Dahl (1955), and Wie-
gert and Evans (1964) have made a detailed study of the
perrenial grass stage on the George Reserve in southeast
Michigan. They recognized two community types; swales

dominated by Poa pratensis and upland vegetation domi-

 

nated by Poa compressa. The succession appeared to be

 

directed slowly toward deciduous forest climax. The oc-
currence of micro—successional cycles was also noted.

Cain and Evans (1952) and Clark and Evans (1954)
carried out a study of the distribution of three plants
in the George Reserve field. Indications of clumping were
found in all three species studied. A further investiga-
tion was made (Evans and Dahl, 1955) to tie the vegeta—

tional structure to environmental factors. Topographic

l6

variability was considered to be the main cause of vegeta-
tional variation. Vegetations of depressions occurred on
a two layered silt loam while soil of upland was a sand or
a sandy loam. Soil texture and depth to plow line also
seemed to be factors. The overall pattern in Space was
visualized as resulting from the interspersion of minor
habitats, each with its own selective forces. A consid-
erable degree of equilibrium appeared to have been reached
in this grassy stage of succession (Evans and Dahl, 1955).

Wiegert and Evans (1964) have studied primary pro-
duction and the disappearance of dead vegetation on the
same George Reserve field, while Getz (1960) investigated
the standing crop biomass of its herbaceous vegetation.

Golley (1960) investigated the energy dynamics of
an old-field community near the Michigan State University
campus. Caruso (1963) examined patterning in an old-field
community in southwestern Michigan.

Other than Dice's (1931) and Beckwith's (1954)
studies, however, there has been little major work done on
the early stages of old-field succession in Michigan. Curtis
(1959) has summarized the work on successional studies in
adjacent Wisconsin and these indicate wide areas of agree-

ment with the Michigan picture.

III. DESCRIPTION OF AREA

The study area was a 10,000 meter square (50 x
200 m) section of a three hectare field on the Michigan
State University Kellogg Gull Lake Biological Station prOp—
erty (See Fig. l). The field is located in Kalamazoo Co.
(Ross Township; T. l S, R. 9 W, Section 8) less than one-
quarter mile from the Kellogg Gull Lake Laboratories on
the corner of Gull Drive and B Avenue.

The study area was located on the east end of the
field oriented with its long axis running north-south. The
area falls in an area of Oshtemo Sandy Loam (Typic Haplu-
dalfs) soil type and is of gently rolling topography.

The field has the following history of croppings:

Wheat (fall) 300#l 5-20-20 fertilizer, 30# ac—

1960 -
tual nitrogen

1961 - Wheat seeded to alfalfa (spring)

1962 - Alfalfa, no fertilizer

1963 - Planted to corn 250# 6-24-24 fertilizer, 100#
actual nitrogen

1964 - Corn 250# 6-24-24 fertilizer, 100# actual ni-

trogen

# = pounds/acre

l7

Fig. 1. Photograph of study area from the north Side in
July of 1965.

I. .’ .4. a a...
m H.441}... ..

t. , (a. .
)\, AM .. .

an
x..

v
.r O‘-
.‘

 

Figure 2.-—Weed control history. A demonstration
experiment of weed control in corn was set up in the fall
of 1962 and Spring of 1963. The following A through F re-
fers to areas located on Fig. 2. The figure represents a
map of the location of plots in the study area.

A. Amitrol T in fall at 2#/acre
Atrazine in spring (May 20) at 2#/acre

B. Same as A

C. Control——nothing fall or Spring

C. 2, 4D Ester

D. Atrazine in
2, 4D Ester

E. Atrazine in
Atrazine in

Atrazine in

F. Atrazine in
2, 4D Ester

in spring (May 20) at 1.5#/acre

fall at 4#/acre
in spring (May 20) at l.5#/acre

spring at 2#/acre preplow
spring at 2#/acre

fall at 4#/acre

fall at 4#/acre
in Spring (May 20) at 1.5#/acre

2

The blocks represent: .Olm Q)

.10m2 IE]

1.00m2 [El
2 I

2

1.01112 matrix —

 

 

 

10.00m

 

 

 

 

 

100.00m

 

 

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IV . METHODS

The 10,000 square meter study area was divided
into four blocks of equal area based on obvious differences
in topography in an effort to minimize topographical ef-
fects as far as possible. Only two of the blocks (I & III)
were used in the study currently reported. Quadrats of the
sizes and numbers listed in Table I were plowed or spaded
between June 14, and 16, 1965. The quadrats were randomly
located allowing for buffer strips between them as listed
in Table I. Quadrats of the 100 and 10 square meter classes
were tractor plowed while the remainder were hand spaded.
Thus there was some variation in the depth and completeness
of soil turnover.

In August of 1965, June and August of 1966, and
June of 1967, all quadrats were sampled with the exception
of the 0.01m2 quadrats which could no longer be accurately
delineated after 1965. Visual estimates were made by the
author of the per cent area covered (%.cover) by each species
for each quadrat. Both the 10m2 and 100m2 quadrats into 100
lm2 quadrats. The cover percentages from these tWOIquadrat

22

23

Table I.-—Size openings created along with the number in
each of the two blocks, the total area opened in each block,
and the minimum amount of undisturbed space around each
Opening. The total area of each of the two blocks was 2,500
square meters.

 

 

Quadrat Area lock Buffer Strip
Size In2 NO°/B10Ck In;B m
0.01 196 1.96 0.20
0.10 64 6.40 0.84
1.00 25 25.00 1.00
10.00 9 90.00 1.00
100.00 2 200.00 2.00
Matrix 1.00 75 75.00 1.00

 

sizes are based on analysis of the pooled values for the
smaller subdivisions rather than on an overall value ob—
tained for the large quadrat.

In addition, 150 (75 in each block) 0.5 X 2m per—
manent unplowed quadrats were sampled in the undisturbed
(matrix) vegetation each time the plowed quadrats were
sampled.

Voucher specimens of species encountered in the

quadrats are deposited in the Michigan State University

24

Herbarium, East Lansing, and/Or the herbarium of the W. K.
Kellogg Gull Lake Laboratory, Hickory Corners, Mich. The
nomenclature used follows Fernald (1950).

The basic statistics on the total data were ob—
tained through use of the Bastst Routine of the Michigan
State University Computer Laboratory. The five per cent
level was used to determine significance throughout. For
the 10m2 and 100m2 plots N = the number of subsample plots
and all statistics were worked on the subsample data as op-

posed to any value obtained for the larger block.

V . RESULTS

A. Pattern of Succession

The pattern of succession varies with location and
climate. However, in many areas it has been found to be
quite predictable within limits. Observation of the fal-
low field in which the holes were cut (the matrix vegeta-
tion) yielded the following pattern: In the fall of 1964
after the corn had been harvested the species found in
Table II were found in the field. The Species are ranked
roughly in order of abundance. In August of 1965, the year
following this corn harvest, the undisturbed parts of the
fallow field (matrix) had a vegetation with a conspicuous
perennial element in its cover. In terms of total per cent

cover Lychnis alba and Rhus typhina occupied first and

 

 

second rank while Potentilla recta was fourth. Annuals and
biennials were next with the ranks being: Ambrosia artem-

isiifolia third, Oxalis stricta fifth, Erigeron annuus sixth,

 

 

Amaranthus retroflexus seventh, Verbascum thapsus eighth,

 

Medicago lupulina ninth, and Chenopodium album tenth

 

25

26

Table II.--Presence list of species found in study area in
November 1964 mostly occupying the rows along with the old
corn stalks. The species are arranged in rough order of
their importance.

 

Amaranthus retroflexus
Ambrosia artemisiifolia
Chenopodium album
Lychnis alba

Rhus typhina

Panicum capillare
Setaria glauca
Agropyron repens
Bromus inermis
Eragrostis sp.
Polygonum convolvulus
Asclepias syriaca
Malva neglecta

Solanum nigrum

 

(see fig. a in Appendix B). The following June these same
quadrats showed the Species ranked as in fig. 9, Appendix
B. Again perennials occupy three of the tOp four ranks.

In August of the same year (Fig. 1, Appendix B) Poa

27

pratensis and Erigeron canadensis shared the top dominance

 

 

rank and the next four most dominant species were perennials

(Potentilla recta, Rhus typhina, Lychnis alba, and Agropyron

 

 

repens in third through sixth total percent cover ranks).
In June of 1967 (see fig. q, Appendix B) these same quadrats
showed perennials occupying all six of the top dominance

ranks, with Poa pratensis now the clear dominant.

 

Thus in the undisturbed fallow field the general
progress of succession following the annual weeds and corn
was a mixture of perennial, annual and biennial species fol—
lowed by perennial - biennial with the biennials declining
after 1966 (see Fig. 3,4).

Unlike this fallow vegetation, the openings cut into
the field in early June 1965 and left undisturbed thereafter
produced an August vegetation dominated by annual species.
In large part these were the same Species that existed along
with the corn crop the preceeding year (see fig. d, e, and

f, Appendix B). Amaranthus retroflexus, Lychnis alba, 32-

 

 

tentilla recta, Rhus typhina, and Ambrosia artemisiifolia

 

 

predominated. In the second year there was a loss Of some
of the first year annuals from the sampled plots (see Table

III). These lost species remained absent in the third year

Average Per Cent Cover

28

  
  

 

 

20 ‘—
s
10 «—
o
’1 Ta Lychnis alba
:5
a
e Erigeron annuus
e
- § ? Y actuca biennis
8/65 6/66 8/66 6/67

Time (samle date)

Potentilla recta

 

 

 

 

.. ' Erigeron canadensis
: .‘-~{?‘“‘““‘-C?‘ L.Eenhasnum_fihapsis
8/65 6/66 8/66 6/67

Time (sample date)

Fig. 3. Change in average per cent cover Of several
Species with time for undisturbed fallow plots.

29

0'

O
1
I

Poe pratensis

8

p
0

P08 compressa

‘ Average Per Cent Cover

Agropyron repens

 

 

 

 

 

l
I

8/65 6/66 - 8/66 6/67

I

Time (sample date)

Fig. 4.. Change in average per cent cover of three
grass species with time for undisturbed fallow plots.

30

Table III.—-Species appearing in 1965 but not in 1966 or
1967. Values indicate the range in average per cent cover

for the various Opening sizes.

 

Species

Range of

Average

Percent Cover Among
Various Opening Sizes

 

Amaranthus retroflexus
Amaranthus albus
Chenopodium album
Chenopodium sp.
Eragrostis reptans
Fragaria sp.

Mollugo verticillata
Oenothera sp.
Panicum capillare
Polygonum persicaria
Portulaca sp.

Solanum nigrum

‘

3 - 38
O - l
O - 2
O - 1
O - 1
O - 1
0 _

0 _

.001

.001

also. In_p1ace of the preceding dominants there occurred

an increase in windborne biennials such as Lactuca biennis,

Erigeron annuus, and Erigeron canadensis, which showed a

Peak in June or August of the second year depending on

31

their individual life cycles. These species then declined
after their initial peak. Accompanying these changes in
annuals and biennials was a gradual increase in several

perennials such as Potentilla recta, and especially the

 

grasses Poa pratensis, Poa compressa, and Agropyron repens.

 

 

 

By the third season the grasses began to dominate locally
in the openings and to displace the annuals and biennials
in dominance. Perennials such as Potentilla recta and

Rhus typhina continued to increase in abundance and a few

 

woody plant seedlings appeared.

B. Opening Size

Opening size appears to influence some aspects of
‘flhe successional patterns. Some species Show significantly
greater percentage of total cover with increased Opening
size, others show significantly less. Significance of
linear trends was determined using both one way analysis
of variance and regression analysis. The five per cent
level was used for denoting significance although it should
be noted that variance homogeneity did not exist in many

cases. Species contributing significantly more cover in

32

August of 1965 with increasing opening size were: Agro—

pyron repens, Amaranthus retroflexus, Amaranthus albus,

 

Eragrostis reptans, Lychnis alba, and Rhus typhina (Fig.

 

 

 

5). In June 1966 similar significant increases were

shown by Agropyron repens, Lactuca biennis, Lychnis alba,

 

 

 

Specularia perfoliata, and Erigeron canadensis (Fig. 6,7),

 

 

in August 1966 by Agropyron repens and Lactuca biennis (Fig.

 

 

8), and in June 1967 by Poa pratensis, Erigeron canadensis,

and Agropyron repens (Fig. 9). No Species Showed signifi-

 

cantly less cover in August of 1965 as Opening Size in-

creased, but in June 1966 Arenaria sp., Specularia perfol-

 

iata, Trifolium repens and Veronica sp. did (Figs. 6,7).

 

 

In August 1966 Rumex acetosella and Poa compressa (Fig. 8),

 

 

and in June 1967 Potentilla recta, Veronica sp., and Poa

 

 

ImDmpressa (Fig. 9) showed trends of decreasing cover with
increasing opening size.

Amaranthus retroflexus exhibited the most striking

 

trend of increasing cover with increasing Opening Size.
This tendency to contribute relatively more cover in the
larger Openings appeared to be related to the Size Of the
plants. Casual estimates showed that individuals ranged

from approximately one decimeter in height in the smallest

408‘- h 33

\ ,
I- I ~ RT

 

 

 

 

 

 

 

 

 

 

 

 

a
o
>
o
t)
.p ' 1 n
5 I I j I
‘3 .01 .10 1.0 10 100 .01 .10 1.0 10 100
S...
6‘3 Opening size (m2)
0
u)
(3
a
0
as
d 5
4 “ LA
5 __
2 --
9 1 -—
‘ I I I II“
.01 .10 1.0 10 100 .01 101 1.0 10 100

Opening size (m2)

F180 5- Average per cent eover plotted against opening

size for species showing trends in August of 1965. Solid
lines are significant (5% level) regressions. Specie are:
AmR, Amaranthus retroflexus; Amfi, Amaranthus albus; AR,
Agropyron repens; AA, Ambrosia artemisiifolia; EC, Eragrostis
reptans; LA, Lychnis albus; and RT. Rhus typhina.

34

Spa

 

x\ Spa
1 1 TR L l J

‘1 I I ' I '
.1 1.0 10 100 . .1 1.0 10 100
Opening Size (m2)

 

 

 

35 *-

Average Per Cent Cover

' .

 

 

 

 

 

.1 1.0 10 100 .1 1.0 10 100
2)

Opening Size (m

Fig. 6. Average per cent cover plotted against opening
size for species showing trends in June of 1966. Solid
lines are significant (5% level) regressions. Species
are: AR, Agropyron repens; ErA, Erigeron annuus; ErC,
Erigeron canadensis; LB, Lactuca biennis; Spa, Specularia
perfoliata; T3, Trifolium repens; and V, Veronica sp.

35

 

‘ Arenaria sp.
n . IArenaria sp.

 

xi 1.0 10 100

 

h
E Opening size (m2)
‘y
4: 3--
G
o
t)
s W
o
0* \
:3 2*’ \
1g \
g 3%-.
I \‘IK .
I \ \’,. PCB-pratensis
.. / 9’». "‘ Poa pratensis
1 ’0’ \
C, ’0’ ’
\ V
i...»x\ 3‘ P08 compressa
\ .
\I‘""'X Poa compressa

l l l
I I l

.1 1.0 10 100

Opening size (m2)

Fig. 7. Average per cent cover plotted against opening
size for species showing trends in June of 1966. Solid
lines are significant (5% level) regressions.

 

 

 

 

 

 

 

 

 

36 3""
2-..
/ ,3 PP
/
/
/
1"- ’./
/
A /
. A
I )... x
c K I . I‘jPC
p ' l I I 1 I I
g .1 1.0 10 1‘00 .1 1.0 10 100
:3
9 Opening size (m2)
.‘3
O
u)
I v --
3 so --
<: 6 __
45 T A
51"\\ 4O ‘- // \
\ \
\ 55 ‘IP I
4 —. I ‘ EI'A . \
\ // 50-"1/ \
31“ \ / 25V " \\-rc
\ \ 20 J-,”“~V_——o .I‘
\ \ / , I' are
2"" \ I / LA 15 1 '
\ \J ’ \
1 ___ o— .—...I>/ 10 'tr\
M
5'", \“~~-~:.::>N<;mA
I I I I I I“
.1 1.0 10 100 .1 1.0 10 100

Opening size (m2)

Fig. 8. Average per cent cover plotted against opening

size for species showing trends in August of 1966.

Solid lines are significant (5% level) regressions.

Species are: AR. Agropyron repens; ErC, Erigeron canadensis;
LA. Lychnis alba; LB, Lactuca biennis; PP, Poa pratensis;
and P0, P08 compressa. '

 

 

 

 

 

 

 

 

 

 

 

30” 37
20 ‘F
16 j; /\
/ \
\
12 v \ / \
\./ \
8 .. /.A\\~ \
\ 'PR
.’ \
-P \
g 4 //.\‘~o \
> \\\PR
8 f I I \I “A
4;: .1 1.0 10 100
0
‘3 Opening size (m2)
3 .
a.
o 3 ‘
u)
m
h
8
.¢
23>
1 1
I l I
I l I
.1 1.0 10 100 :1 1.0 10 100

Opening size (m2)

Fig. 9. Average per cent cover plotted against opening
size for species showing trends in June of 1967. Solid
lines are significant (5% level) regressions. Species
are: AR, Agropyron repens; Ere, Erigeron canadensis;
PC, Poa compressa; PP. Poa pratensis; PR. Potentilla
recta; RA, Rumex acetosella.

 

 

38

openings (0.01m2) to a meter and a half in the largest
(lOOmz). Flowering and seed production occurred through-
out the range of sizes but the number of flowers and Seeds

appeared to be very much larger in the larger openings.

C. Opening Size and Community Composition

If the existing vegetation has an effect on incom-
ing species, and if Size Opening affects establishment and
survival of species, then the species composition (species
hierarchies) of the different sized openings would very
likely be different. A comparison of the different Sized

Openings with respect to species composition was made using

 

the coefficient C = of Bray and Curtis (Austin & Or-

A + B
loci, 1966), where W is the sum of the lesser values of
species scores in common in two stands and A + B is the sum
of species scores in each stand. Random samples of equal
total area (13m2) were chosen from the 1-100m2 size classes
while all of the 0.1m2 plots were used, these being the
determinant of the 13m2 total area. The species scores were

the average percent cover values. The coefficients obtained

are presented in Table IV.

39

Table 1V.--Coefficients of Similarity between vegetation
developing in openings of various Sizes cut into newly
fallowed corn field.

 

 

Opening Sizes August June August June
compared 1965 1966 1966 1967
0.1 — 1.0 .500 .820 .724 .710
1.0 - 10 .800 .740 .705 .645
10 - 100 .555 .680 .725 .715
0.1 - 100 .361 .640 .805 .770

 

It can be seen that the smallest similarity coef-
ficient (i.e. the greatest vegetation difference) occurs
between the 0.1m2 and the 100m2 openings in the first grow-
ing season. Since the coefficients do not show a clear
trend with increasing opening Size, even in the first year,
the strong trends with opening size shown in the cover of
particular Species are probably obscured by the normal high
variance in the bulk of the other species which is unrelated

to Size opening.

40

D. Effect of Initial Species

 

In the light of several earlier studies (e.g.
Keever 1950, Rice 1967) it would be useful to know whether
the species present at the initial stages of succession
have a determining influence on the Species composition of
later stages.. For the 128 0.1m2 openings plots were made

of the per cent cover of Lactuca biennis, Erigeron annuus,

 

 

Erigeron canadensis, Lychnis alba, Poa pratensis, Poa com-

 

pressa, Ramex acetosella, and Potentilla recta in August

 

 

1966 versus the cover of Amaranthus retroflexus in the pre-

 

ceding August of 1965, the initial dominant that year in
the Openings and the species most sensitive to size or
Opening (see Appendix C for graphs). For none of these
species was their cover in 1966 directly correlated with

the amount of Amaranthus cover in 1965 as determined through

 

observation of the regression graphs, Appendix C.

VI . DISCUSSION

The complicated process of succession is a quasi-
predictable (and therefore quasi—orderly) sequence of di-
rectional changes in the species makeup and dominance hier-
archy among the biota on a Site. These directional changes
are wrought by the germination or expansion of species al—
ready present on the site together with immigration, estab-
lishment, reduction and local extinction of these various
Species populations. There seems little question but that
the Species already established on a site would exert some
influence on the probabilities of success of species ap-
pearing subsequently. The Species already present might
influence germination, seedling survivorship, size of plant,
and reproduction and longevity of adults. Modifications of
this older vegetation by breaks or Openings in the plant
cover is one way to study two questions experimentally:
over what range of opening size are the effects of such
interference by established species detectable? And, do

the various Species respond similarly to such Openings?

41

42

In the corn crop annual weeds such as Amaranthus

 

retroflexus, A. alba, Chenopodium album, Ambrosia artem-

 

 

 

isiifolia, Setaria viridis, etc. occur, but the corn it-

 

 

self is the clear dominant. Weed control and other manage-
ment Operations influence both the amount and kinds of
weeds that occur with the crop. In the field studied, fal-
lowing without disturbance after the October 1964 corn
harvest gave rise by the subsequent late summer (August
1965) to a vegetation having a major component of non-

annual Species. These were Lyghnis alba, Rhus typhina,

 

 

Potentilla recta, and Erigeron annuus. Although definitely

 

 

secondary some annuals were still present such as Ambrosia

artemisiifolia, Oxalis stricta, and Amaranthus Sp. By the

 

 

following summer (August 1966) Poa pgatensis had achieved

 

first place, and although a biennial (Erigeron canadensis)
occupied second place, the characteristic grassy old-field
vegetation of southern Michigan was clearly emerging. The

June 1967 dominance hierarchy Shows the grassy nature even
more clearly.

The presence of so much Rhus typhina (staghorn sumac)

 

in this field is a Special circumstance owing to its persist-

ence following planting as a cover plant in an abortive

43

attempt to establish a walnut orchard many years earlier
(personal communication from Mr. Harold Webster).

On the Openings made in the fallow corn field in
June 1965, a pronounced dominance by annual weeds occurred.
The vegetation in these Openings was developmentally the
same age as the corn-weed mixture that preceded the fallow.

Amaranthus retroflexus is clearly the Species favored when

 

the soil of a fallow corn field is turned over in early

June in Michigan. Lychnis alba, though not an annual, is

 

also high but such other annuals as Mollugo verticillata

 

and Ambrosia artemisiifolia tend to be among the top five

 

species in total cover except in the very smallest open—
ings (0.01m2). The perennial grasses are well down the
dominance hierarchy in the first growing season. By the
subsequent late summer (August 1966) biennials, especially
Erigeron spp. and Lactuca spp., took over the most promi—

nent role. The perennials Lychnis alba, Agropyron repens,

 

 

and Rhus typhina were definitely present but secondary.

 

This greater importance of biennials and lower importance
of the perennials is a major difference between the undis-
turbed corn fallow and the openings made in it when they

are compared after the same length of development (i.e.

44

matrix August 1965 compared with openings August 1966).

In particular, Erigeron canadensis was much less impor—

 

tant in the undisturbed fallow than in the Openings. This
could largely be a matter of seed source buildup, the

weeds in the corn crop providing a very low inocculum of
this Species. Other differences were the greater importance

of Agropyron repens and lower cover of Lychnis alba, Poten-

 

 

tilla recta and Oxalis stricta in Openings than in the un-

 

 

disturbed fallow. It is not possible to demonstrate whether
these particular differences are significant due to the high
variance inherent in this vegetation. However, as noted

earlier, Agropyron repens does exhibit a positive correla-

 

tion with increasing opening size which tends to support
the notion that something about the undisturbed fallow sit-
uation is less favorable for the Species. Some, but not
all, Species that had higher cover in the undisturbed corn
fallow than in the openings (e.g. Oxalis stricta, Poa com-

pressa and Potentilla recta) tend to exhibit negative re-

 

gressions with size of Opening in the fallow vegetation.
All these Species are likely candidates for future studies

on mechanisms in old-field succession.

45

The data presented in Figs. 5 through 9 show that
the per cent cover of some species tends to increase sig-
nificantly with increasing Size of Opening while other
Species show a significant decrease. Of the species signi-

ficantly positively correlated with Opening size Amaranthus

 

retroflexus was the most pronounced. It was the dominant

 

in all openings except the smallest (0.01m2), in their first

growing season. Amaranthus retroflexus has a large capacity

 

for plastic response and its greater per cent cover in the
bigger Openings appears to be more a reflection of increased
size of individuals than increased numbers per unit area.
Viewed in reverse this would suggest that increased fre—
quency of establishment of individual plants is inadequate
to compensate for the dwarfing effects of the interference
by surrounding one year older follow vegetation. The re-

lationship suggests that Amaranthus is very sensitive to

 

interference from established species or from its own de-
composition products Of the preceding generation. The
vegetation surrounding the Openings at this time was domi-

nated by Lychnis alba, Rhus typhina, Ambrosia artemisiifo-

 

 

 

lia, Oxalis stricta, and Erigeron annuus. Amaranthus either

 

 

 

requires a large area essentially free of effects of these

46

species or of some other characteristic of the one year
older vegetation in order to achieve maximum growth.

While it is tempting to Speculate here that herbi—
cides used with the corn crop might also be involved, the

presence of vigorous Amaranthus plants with the corn crop

 

itself argue against such an effect.

Unquestionably Amaranthus requires some minimum

 

area free of Significant interference for establishment.
This minimal area is smaller than 0.01m2 since the species
had about 3%.average cover in these smallest openings and
reached a maximum of 90% on some. Occasional individuals
or clusters of individuals were also present in the undis—
turbed one year old fallow vegetation where this species
ranked seventh from the top in total cover contribution.
However, the minimal interference-free area probably has

a very low frequency after this first full year of fallow,
since Amaranthus disappeared from the samples after then.
It has been suggested (oral communication Rice, 1967; Gregg

and McCormick, 1966) that Amaranthus, like other first year

 

old—field annuals (Keever, 1950), may be inhibited by its
own decomposition products as well as those of other old—

field species.

47

The direct correlation between per cent cover of

Amaranthus and area of opening may reflect allelOpathic or

 

other kinds of interference by surrounding one year older
vegetation. The zone of major interference can hardly ex—
tend all the way to the centers of the largest 100m2 open—
ing size. Possibly this is simply a reflection of a de—
creasing ratio of the area of the inhibited zone to the
total area of the Opening, i.e., if we were to assume the
interference to be restricted to a band one meter inward
from the older vegetation, in the 1m2 Opening the entire
area would be subject to interference, in the 10m2 open-
ing only about 92% of the area, and in the lOOmzopeningS
only about 36%‘wou1d be influenced. A comparison of per

cent cover of Amaranthus retroflexus in 36 central versus

 

36 perimeter 1m2 plots in the 100m2 blocks Showed that for

the 100m2 blocks Amaranthus cover was consistently less

 

in the perimeter plots. This difference was significant
. 2

at the 5% level (t test) in two of the four 100m blocks.

This tends to substantiate the idea of interference as a

cause for decreased cover of Amaranthus.

 

No attempt has been made as yet to characterize the
nature of the mechanisms responsible for the dwarfing of

Amaranthus.

 

48

The positive trends of more cover with increasing
Opening Size found for other Species, especially in the
second and third growing seasons, may be a result of simi-
lar interference phenomena. It would seem that there might
be a positive correlation between per cent of the area bare
of vegetation and Opening size since invasion by the older
peripheral vegetation, especially the grasses, would reach
the whole Opening in the smaller ones more rapidly. This
in turn would permit species which require bare area for
establishment or persistence to remain longer and in greater
abundance in larger openings. Thus some of the positive
trends found may be due to the varying rapidity with which
different sized Openings are occupied by perennial vegeta-
tion. Or stating it another way, they may be due to the
variation in amount of bare or competition-free area in the
different sized Openings.

Some of the negative trends with increasing opening
size may simply reflect the slower rate of invasion from
the surrounding one year older undisturbed fallow. g g Egg-
tensis, for example, eXpands vegetatively in addition to
new colonizations by seed. However, as noted above, this

species increased its per cent cover in the undisturbed

49

fallow vegetation more rapidly than in the openings cut
into this vegetation. This could be an interference phe—
nomenon in the Openings from the greater impact of Amagag—
Ehgg there. Also, it could simply be a more successful re-
tention of fertilizer residues missed by the corn crop by
393 plants established slightly earlier in the succession
and subject to less bare ground leaching. Potentilla recta
also exhibits higher cover in the original fallow array and
less cover in the larger opening sizes.

The possibility exists that some of the species ex-
hibiting significant positive correlations with opening
size may simply reflect a greater interference effect from
the species noted above which are more important in the

smaller openings. Erigeron canadensis, for example, might

 

be adversely affected by higher Poa compressa cover. Cor—

 

relation studies of the percent cover of these two Species
in the various individual quadrats did not reveal any such
trend. The number of samples available was far too small
for identifying any but the most spectacular correlations
so the lack of significant correlations can hardly be given

great weight.

50

The positive relationships of cover with Opening

size for species such as Rhus typhina, Agropyron repens,

 

 

Lychnis alba, and Poa pratensis may be related to their

 

 

large vegetative reproductive organs which survive plowing
well. This gives these species a distinct advantage in the
initial re-vegetation of the large Openings where most of
the other species must start from the seedling stage. All
four species appear to be able to contend with the higher

cover of Amaranthus retroflexus that becomes established

 

in these large Openings.
The most convincing negative regressions between

species cover and size of opening are those of Poa compressa

 

and Potentilla recta. Three other species (Rumex acetosella,

 

 

Trifolium repens, and Veronica sp.) exhibit significant neg—

 

ative relationships but they are species of small total coven
and it is very possible that underestimations of per cent
cover, or the possibility of being overlooked, is much
greater for such small or less common individuals on the
larger sample units.

Of these, however, it is to be noted that legumes

such as Trifolium repens are said to be adversely affected

 

by decomposition products of first year dominant annuals

51

(Rice §t_§l,, 1967). It is possible that the greater masses

of decomposing Amaranthus on the larger Openings produced a

 

greater suppression of these legumes there as the hierarchies
indicate a trend of decreasing legume cover with increasing
opening Size in June of 1966.

The particular weather sequence that precedes and
accompanies the initial establishment of a vegetation on
agricultural land is undoubtedly an important variable.

No effects are directly relateable in the present study but
June and July of 1965 had some droughty periods in the
study area. The rhizomatous perennials in the larger open-
ings may have been favored by this more than seed—started
species.

The dominance hierarchy was suggested (Whittaker,
1965) as a useful method of portraying both the biomass and
the site's resource allocation among the species in an eco-
system. With large representative samples of a vegetation
on a homogeneous area these curves tend to approximate the
log—normal curve discussed by Preston (1948, 1960) and Clark
gt_§1,(1964). Numata and Yamai (1955) have Shown that in
annual weed vegetation the hierarchical order changes among

the species with the season. Also, their curves were

52

characterized by flat plateaus which indicated that several
Species tended to share the same relative dominance position.
In the June 1966 hierarchy of total cover for species for
this study similar plateaus occur (Appendix B, Figs. i, j,
and k). It is suggested that these reflect interim values
and as interaction between the species becomes fully de-
velOped the log-normal hierarchy tends to be the final out-
come. Ogawa and Kira (1953) and more recently Harper (1967)
have pointed out the tendency for the log-normal relation—
ship to develop in competition. Interacting plants with-
drawing resources from the same pools tend to bring posi-
tive feedback into play wherein the individuals getting the
slightest advantages in withdrawing resources utilize these
resources to build bigger resource trapping machines (roots
or tops) which in turn enlarge the advantage. It is pos-
sible that under more controlled experimental conditions
with more uniform Species arrays, careful study of the
shifting hierarchical positions among the Species may give
clues to when and between what species such interactions
might be anticipated. In the present study, however, there
was far too much variation and the observations too widely

spaced in time to draw much from these hierarchical changes.

VI I . SUMMARY AND CONCLUS I ONS

The course of succession is slightly different in Open-
ings created in a fallow vegetation as compared to the
succession in the undisturbed fallow itself, even when
the openings are made the early June following the corn

crop.

The agricultural manipulations made for the corn crop,
such as herbicides, high fertilizer, and cultivation,
as well as effects from the corn plants themselves are

missing in the Openings.

The corn-annual weed first year vegetation of the corn

field is represented by the Amaranthus retroflexus-

 

dominated vegetation in the openings.

In the second year the fallow corn field becomes domi-
nated largely by perennials, although the biennial,

Erigeron canadensis, is prominent.

 

The Openings on the other hand are dominated in the
second year by biennials. This difference may be due

53

54

to several causes: greater biennial seed inocculum in
the openings, smaller fertilizer residues, or possibly
a greater resistance to decomposition products of Ama-

ranthus retroflexus. None of these possible causes was

 

experimentally evaluated.

By the onset of the third growing season, the differ-
ences between the Openings and the fallow corn land

become less but Poa compressa and Poa pratensis are

 

 

generally more prominent in the fallow than in the Open-

ings.

Smaller openings are very much more like the fallow
corn than are the larger openings, but this difference
which is great the first year wanes by the third grow-

ing season.

The per cent cover of 14 of the 77 species appears to
be correlated with the Size of the opening. Of these
14, the most dramatic effects were observed in Amaran-

thus retroflexus which is significantly positively cor-

 

related with increasing opening Size across the range

of 0.01m2, 0.1m2, 1.0m2, and 100m2 areas.

10.

11.

12.

55

This increasing per cent cover of Amaranthus in the

 

larger openings is accompanied by an increase in size

of the Amaranthus plants. The mechanisms responsible

 

for the dwarfing in the smaller Openings have not been

determined in this study.

Positive correlations between per cent cover and in-
creasing opening size were also observed for other
Species, several (Agropyron repens, Lychinis alba,
Rhus typhina, and Poa p;atensis).being populations
largely derived from vigorous vegetative propagules

which survive plowing in the Openings.

Some Species appear to produce greater per cent cover
in the smaller openings than in the larger ones. In
general these are species that also show greater per
cent cover in the undisturbed fallow vegetation. No
attempt has been made in this study to investigate the

mechanisms that might produce such effects.

. 2
Results from this study suggest that the 10m and the
100m2 opening sizes are not apt to yield important in-

sights into germination and establishment processes in

13.

14.

56

old-field vegetation. This study together with that
of Caruso (1963) leads to the recommendation that
smaller Openings, perhaps 1cm2 to 100 m2, will be most
likely to give clues to processes Operating in early

old—field succession.

While some clear vegetation differences are observed
in the Openings made in first-year fallow vegetation,
this study also indicates that older vegetation some—
where between this young age and the 30—year old grassy

field of Caruso (1963) may yield the best study medium.

For the range of sizes used, it seems that the size
Opening does not affect the pattern of succession by
altering Species composition, nor does it seem that the
initial dominant annuals have a major determining in-
fluence on the pattern of succession. This latter is
suggested by the lack of correlation of any dominants

in the second year with per cent cover of Amaranthus

 

retroflexus, the first year dominant. At least Ama-

 

ranthus retroflexus does not seem to strongly control

future community organization.

15°

16.

57

In the long run it might be the initial perennial spe—
cies composition which may be a greater determinant in
early stages of Old—field succession. Through their
ability to invade and hold space, the early perennials
may be the controlling factor in determining the pat-
tern a given succession takes and also the vegetational

patterning in Space seen in the field at later stages.

Dominance hierarchies (Whittaker, 19657 Numata, 1955)
based on total cover are not a great deal more useful
than conventional summaries for visualizing the make-up
of old—field vegetation or the changes in it, either
within the same growing season or in comparing years.
However the hierarchies show up some things worth in-
vestigating further, e.g. the close spacing of the tOp
two dominants at times and the plateaus such as occurred
in the June 1966 samples. This "close Spacing" or pla—
teauing of the tendency for a more log—normal hier—
archial arrangement may have merit for identifying po—

tentially interesting species combinations.

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59

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6O

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61

Keever, C. 1950. Causes of succession on old—fields of
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62

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APPENDIX A

LIST OF SPECIES OCCURRING IN SAMPLES

APPENDIX A

LIST OF SPECIES OCCURRING IN SAMPLES

Achillea Millefolium L.
Agropyron repens (L.) Beauv.
Amaranthus albus L.
Amaranthus retroflexus L.
Ambrosia artemisiifolia L.
Anthemis arvensis L.
Arenaria sp.

Arabis glabra (L.) Bernh.

Aribidopsis Thaliana (L.) Heynh.

Asclepias syriaca L.
Aster sp.

Barbarea vulgaris L.
Bromus tectorum L.

Capsella Bursa-pastoris (L.)
Medic.

Carex sp.
Chenopodium album L.
Chenopodium sp.

64

Chrysonthemum Leucanthemum
L.

Cirsium vulgare (Savi)
Tenore

Digitaria sanguinalis (L.)
Scop.

Eragrostis reptans (Michx.)
Nees

Erigeron annuus (L.) Pers.
Erigeron canadensis L.
Fragaria sp.

Galium Aparine L.
Geranium sp.

Hypericum sp.

Lactuca biennis (Moench)
Fern.

Lactuca canadensis var.
longifolia (Michx.)
Farw.

Lepidium canpestre (L.)
R. Br.

 

. [I ‘1! ,- i'

65

Lepidium virginicum L.
Lychnis alba Mill.
Malva neglecta Wallr.
Medicago lupulina L.
Medicago sativa L.
Medicago sp.

Melilotus alba Desv.
Melilotus sp.

Mollugo verticillata L.
Nepeta Cataria L.
Oenothera sp.

Oxalis stricta L.
Panicum capillare L.
Phleum pratense L.
Physalis pubescens L.
Plantago lanceolata L.
Plantago Rugelli Dcne.
Plantago virginica L.
Poa compressa L.

Poa pratensis L.
Polygonum Convolvulus L.

Polygonum Persicaria L.

Portulaca sp.
Potentilla argentea L.
Potentilla norvegica L.
Potentilla recta L.
Rhus typhina L.

Rumex Acetosella L.
Rumex crispus L.

Rumex obtusifolius L.
Setaria viridis—glauca
Silene antirrhina L.
Sisymbrium altissimum L.

Sisymbrium officinale
(L.) SCOp.

Solanum nigrum L.
Solidago sp.

Specularia perfoliata
(L.) A.D.C.

Stellaria sp.

Taraxacum officinale Weber
Tragopogon major Jacq.
Trifolium hybridum L.
Trifolium pratense L.

Trifolium repens L.

66

Trifolium sp.

Ulmus sp.

Verbascum Thapsus L.
Verbena sp.

Veronica sp.

Unknown grass seedlings
Unknown rosette PVL
Unknown rosette
Unknown seedlings

Unknown L

APPENDIX B
GRAPHS OF TOTAL PER CENT COVER OF SPECIES
VERSUS SPECIES RANK (BASED ON TOTAL COVER)

FOR ALL SAMPLING TIMES AND OPENING SIZES

68

103000 1'

.lb

1000

‘0-

100

. snafiouoaafla aoaaanoa;

a .Qm Esacomosono

. sapwofimnog EssowhHom

. , azaaomwmsnno Noesr
.I. . onQAOAMMo Esoaxapme
. mwswaccom nsodx:D
. ammonmfioo mom
.6» mspofiaficz

omnoucpa Estouwa

mwswaomom macho.

wHHomouoom Nessa
55pm“: Enamaom

.dm «Hhqumfia

. mdmcccanmo sonowwpw
acacHwIchwpw> mwpxpom
maanoL mwumopwmpm
mwmcopwpg mom

masco«n monuoaq
65H5>Ho>coo Somewhaom
anodes cophm0pw<
Eznaw SSwUOQosono
wsflfifidafl owwowcoz

. mSKcHLOApop mflQpCcpaE<
mssncw nopowfipw

sunflppm mfiHwKo.

«poop afifiauscpom
anaouaamasmppm wamopned

wcfinahp mafia,

M «paw ”assess

-
a

—b

o. . 1.
1.

po>oo 9600 new Hana?

mamawnp ESOmwQLo>.

I I II I II I l' I II I 'I II I 'l I II I II'I I,

p . lb
4 I la

Ranked Species

abundance hierarchy f0

" undisturbed
nked by total

A

Species rs

Species
fallow plots in August 1965.

cover found in 150 plots.

Fig. a.

69

mfipwwan> monmnawm
msoomonsm mwammhnm
moawo>poa mHHHpcmpom
.Qm mpogpocoo

manam manucamed

mbfipwm omwowcoz.
wflpaumo mpcmoz.
scams cowomomwne

upwflooosmfi omwucmwm
opamfisb Enampfio
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Hbm Gsocxab

monsompw mHHHpcouom

.dm ESAHOMHpB

-
_

109000
1000

100 4"

1r-
db

-
I
n» 1.
1.

po>oo uaoo you H1309

0 ‘L I II I 'l I II I II I II I II I II I II I II I II

'Ranked Species

Continued

Fig. 30

70

I
.1-

109000

1000

‘II'

100

o Sande afifiponosono
onwflafiawo Baowcwm.
aostwImeanfi> «weapom
snag» 25m
epoch waafipnouom
mwaflaooom mango
waaomopoom Nessa
mwcaacoom soqup.
ands macAOSQW
msxoamonpop manpcmme<.
«newspm mwamxo
mwnwacoom nsocxnb
cpwaawoappo> owsaaoz,
anodes coshnopw<.
banana nonowwpfi.
P _
I d .«

nu. 1.
1

‘F
.1

no>ou ucoo pom Hana?

Ranked Species

.01m2 opening

ranked by total per cent

’1
Q

ndance hierarchy f0
Species

Species abu
cover found in 592 plots.

plots in August 1965.

F18. be

71

‘-

103000

1000

qu-

100

o . enemas Benson...
o Banana SHcOQOsQSI
. mosanIuHch: 393$ I

o assume.“ mwpmocwmpm I.

o manganese momI

o 0.3.5.360 Esoflcmm I

o mfiHOMHHmflEcppw $30,584 I
0 .mm wflhwunHQI

e _ mwpmmflg mopmnpem I.
nfisccc copewwLWI

a mmcflflcoeh weasel
o . «HHomOpoom KefismI
magmas ammoacesl

magnum manudanwsd I.

332603 £30255 I.

gauge?» "3er

unease, mwamxo I
epoch eHHHucopom I
anodes defiance? I

«Spam owwoweez I
macadaowppeb owgaoz I
. gnaw mafiflohfil
uaofiuonn on manucesméw I

. _ .
fl ,1 q
0. 1.
1

p260 9600 new Hence

.
d
.

.JL

0

Ranked Species

'Specics abundance hierarchy for 0.1m2 opening

plots in August 1965.

Species ranked by total per cent

cover found in 128 plots.

Fig. 00

72

‘-

109000

. mwcHHcoom mango o I.
mosmeIchHpr «Heepcm a I
Ssan: Escwaom o I
h .mm «Hammdhmm a I
mHmfiepwhm mom. a I
.Qm eonnomhm o I.
omcopanm_SsHHomee a I
mHmsocncao nonmenL. o I
msHHOHHmnpno Kefisr o I
. a. okaHHHmdo ESOHcam I
a mHmamnp Enomepgo> I.
o _ .Qm «HamprHnI
a m9Hs>Ho>fico Esnowhaom..
I. mpoanm mHHexo I
. mHHonOpcoa Kcfisr I
o . nuance dopoanw.l
o 539?. achoaocmno I
e muooflwec m>HeEI
e . mamas maanapwE<_I
a unmade.“ memccmepr
o . mpprm owwOHcoz I.
0 $33323 owsflos I
a name?» Gogmopwxa I
a emmmpdfioo com I
o aanES 9.55 I
a meonmpom Epsothom.l
o mHHOHHHnHEopnm mHmopne<.I
e _ epoch eHHHpceuom.I

_ . n H p
H . . ‘

nu. 1.
1.

-

.1
db

‘1

1000
100

po>oo pace nom.aeaoe

wanna m Hanohn I

q

@338 0.5 on manganese/e. I

L
d

0_

Ranked Species

Species ranked by total per cent

Species abundance hierarchy for 1.0m2 opening

plots in August 1965.
cover found in 50 plots.

Fig. do

73

10 9000

' 1000

4L—

qu-

100

"1"

a . annoyance domI

e _ .mm «Hanson<I

o M .mn domflsupomI
.obHeGHOHuuo ESOHKaamBI

e . mHmcecwcao noaoprpII

o m uncomcpna mHmemnmI.
o a mammHao KoEer
e aHHemoueoe KcEsmI
chcoHo. mofipoeAI

xpoMApm mHHwKOI.

55pm H: EsceHomI

mnHHomHmsuno Neser
.wosEHwIchHaH> eHampemI.

woprhn deQcHeQ<I

mwsHHceon mmeao.l

3558 nosomHfipI

.Qm meaprHnI

chmHHHcao EsoHsmm..

assumes memoammawn.

m5H9>Ho>coo Escomhaom.I

manm msmpcmpwfie I

Eznaw ESHcouocono I

enemas cogdoame I

«noon mHHHucouom..
epaHHHOHpnob owSHHo:.l

c5393 3:? I

eHHoyHHnHEopae mHmcapE¢..

38 3503 ..

ezkcamonpcp mssucenwEd.I

_ P b —
. i H J _

Ranked Species
Species ranked by total per cent

Species abundance hierarchy for 10mg opening

plots in August 1955.

H
q
0 . 1 0
1

ao>oo uceo pom deuce

coverfound in 18 plots (182 subdivision plots).

F180 60

74

‘-

10,000

“-

1000

fir

100

..osHHouHmspno Keeam.
mpdnoeocea ommpseHm

oncogene SJHHoanB
censowpm.wHHHpnoadm o,

C‘-

9 69H9>Ho>coo ezsowaom

300
III!

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o EshmHn Esfianom.r
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a . spoon eHHHerpom I
o mwGHHUcem :aocxsbr.
9 . 33333? omsflos...

.mm theunHQ

Esnas echomoccno
assume coccprE
onsHHHnwo Eoncwm
aoflmfiwIchHLH> mewaom
mwsHHccem macho

msanao Kcesm

anodes nephaopw<
aHHouHHmHEcuaw choppfid
accused mHumOLwepw
mamas manpcspce<
mania» 2.5

spam nHacoeq
esonMompos msnuceams¢ I

_ , b _ L
, _ d _ J

«L-

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1

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Ranked Species

Species ranked by total per cent cover

8

t

O

1

D.

2

m

0

O

1

P

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o :3 Eonnoahm I

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anodes ESHHomeB..

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ammopmfioo com I

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e559? 35w I

ecHHzQDH owechesn.

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1 l

o. 1 0
1 .

p .
H H

«—

L¢>oo pace Lem Hence

Ranked Species

Species abundance hierarchy for undisturbed

fallow plots in June 1966.

Species ranked by total

per cent cover found in 150 plots.

Fig. g.

76

‘-

103000

1000

H»-

100

BE 5383:.

, mHmno>aw mHEonuG¢
. eumHooocmH omwustm

wcHnapHpce chHHm.

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L _ . p
_ d H

Au. 1.
.l. .

p¢>oo uceo Lem Hence

01

Ranked Species

F 1g . 8 continued .

77

. «macaw mHnmn¢
ecHnnaHpcm cacHHw.
EsaHmmHuHe EsHpQShmHm.

wpmaooocmd omepcmHm
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O

o
o

p
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o .
1

«+
Hr—
«r-

10,000 7-
1000
100

mammHno Meant I
. mm anm new I
hOwdE nowomoweae I

one mnpoaHHoz I.

omaeuwsn EsHHouHaB I

.eHHOHHHmHEepnw «HmOpQE< I

Essence» msaoam I
ammopmsoo com I

«HaowOpeow NoEsr I.

anodes ccphmoaw¢.I
eanmhp mnnm I
.Qm mOHsono> I
e>Hpmm owoncoE.I

mHmcepeaa won I.

_epeHHompom wHamHserm I
daemon EsHHOMHpe I
spoon wHHHpaopom I
wnHasapH owoncozmI

mHacoHn mospomn I.

epr mHsnohq I

.Qn preseAd I
aHucccaamo concMHpE.I
masses GoncprE I

L

I

a d

A
1.. 0

ae>eo uceo Lem Hence

0
I I II I II

Ranked Species

Species ranked by total per cent

Species abundance hierarchy for 0.1m2 opening

plots in June 1966.
cover found in 128 plots.

Fig. he

78

‘-

10 3000

‘—

«r-

1000

I.

«OHusaH>nowsaneHm
gfiHemeHe EsHpnfihmHm
mHmmmnp Enemappo>
oncogene. ESHHOMHLB o

100 ‘1”

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O
o
9

3
II I II I I!

aches nowavwmnaI
93.3% mHnendI
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.dm EsoHaoahmI

0 333338.“. 3335...

eanaaHpsw cacHHwI
used?“ ESHHOMHE. I

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A? EBOHHHoEI
ammopQEoo com!

euwHHom pen preasoeam I

H r
d H
nv
1.

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:3 doHccae> I
35:93 mnfimI.
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oppmcmeo £36309 I
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anodes sophnoam<..
«Haemouooc Keenan!
gnaw mHHEES I
chsoHp cospomqru
.mm sHLecop¢CI
menace :oacanv.I
I 1 l

1. .0

as» 09

Ranked Species

Species ranked by total per cent

Spedies abundance hierarchy for 1.0m2 opening

plots in June 1966.
cover found in 50 plots.

F180 10

79

10 9000

1000

J.-

100 ‘k

eopnomaa.eaaencopoa. o.
EsEHe 35 He EsHathmHm .

Cli-

a £3. Eonaoahm I
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e nHQOnp Esomepne>.l.
o . ocHnmmw ESHHmo.I
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msHHOHHmsnno Nessa I
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oncogene EsHaaHnB II

. msmmHLo Madam I
ecHQLAHpsm cceHHm I
doathm mmHmoHome I

.Qm 80Hcopo> I

anodes SSHHOMHLE I.
senescence mom I

mHmSopeaQ mom I

«GHSES mg? I

ecHHsmzH owwOHpczI
wHHomOpeoe K0836!
ansoomcwo noncmHaE..
ecumemEmo EsHpHdcn I
eveHHOHaoQ praHnocmm;I
anode.» GOESOLM¢ I

snoop mHHHnsepomTI

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mHGGOHn mogomu I

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b
q

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a q A

O 1.. 0
1

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Ranked Species

ndance hierarchy for 10mg opening
Species ranked by total per cent

Species abu
cover found in 18(162 subdivision plots) plots.

plots in June 1966.

10.000 T 80
1000 --
10° 4*" . ' I
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p
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0 “ I II I II I II I II I II I II I II I II I II I II

Ranked Species

Fig 0 5 con tinned e

81

‘F'

109000

~-

1000

.nm 5:0Hacahm o
ouccuwhn_snoanm ..o
echHoHHmo Bsonehee
EsSHnnHu He EsprshmHm o I
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o .90 09003ch I

c 89.009000 msanm I

e enpwaw 25004 I.

s 053093390 Keenr I

e . gages» Enomcppo> I

a. mHmao>pm mHEecScd I

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9 000398.. ESHHOHHLB II

a eHHOMHHmHEoupw eHmoaQE<..

o macaeh.E9HHo.HHpB I

e .372: nomenomepe I

I 0.3ng mopennmm I

o eaHHsanH owoncoz II

I .. 0.5000500 EchHmeq I

9 :3 00.30.03, I
senescence com I

_ «noes wHHHpccuom I
. msamHLo Refinm I.
03:30.5 com I

came precop¢ I

SEES 3ng
epmHHoupon eHaeHsoodm..
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cacao; confines“? I
52 3:53 I
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652.50 nepomHaE I

P .- .

1 d J

0 . 1 0
1..

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b
1

qr-
.-
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100

nebco pace pom H.309

Ranked Species

Fig. k0

plots.

Species ranked by total per cent

Species abundance hierarchy for 100m2 opening

cover found in 4(400 subdivision plots)

plots in June 1966.

82

I
d‘

10 3000

an.

1000

‘-

HHHomsn owauaaam M
omconapm Eseanm a
woSanImwuapn> maawpowq a
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opmmHsa wogwppwm. s
mwmownu adomwppo> e
«cocoonsn mHHamham a
dowmobpoc «Hawucouom -
a . n>m agocxcp
a nsmmwao Kossr.
e .mm Esownonhm
9 .dm mspoafifioz
0 .nm EnHHoane
9 .mm omacHHom

100 “1"

d-

unomoa.ssuaohwhe

o condemns aHHHucoaom

o .ESHHO%mflHHE mHHw£o<n

o oamdaogymo Enowxanma

a aaaasmsfi owmoauoz

o , wands mopoaflaoz

o omnopmgn ESHHOMHgB
9 . mwcnowp wfiWuowH
«Haemopoow Hoenr

.wfiaouaamHSepna mflmopos<
ammoamfioo mom

mssccm coyomflpfi

macaw; coghmopw¢.

. prm madnohn
48.393 35m
«coop mHHaucOpom

naocaomcwe copowwpfi.

mwmcouapn won

.1.

1

10.1-

hoboo 9300 son H1909

.

. o . L
4 d J

0

Ranked Species

Species abundance hierarchy for undisturbed

fallow plots in August 1966.

Species ranked by total

Fig. 10

per cent cover found in 150 plots.

83

‘-

103000

msxoahonpop unmanannad
.mm manapamfin
muowppm meaxo
m9H9>Ho>coo abnowhaom

. «0335323 mapmuom o

I

anwannpa:owaowooz
ammonnfioo com

n>m neonxnb
nomenonnn mHHmmhsm

a «HHOMHHmeopnw mamoaosd

‘r-
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p .
u a

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1

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100 "‘

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minnows wosuomqo

aHHomOpoow meant
mnflnnhu msnr
mfimceumpn mom

2:3 Eases
masque nonowaam

naunocmcwo conowfipfi

- p
a q

1

pupae 9500 new Adan?

4L.

0

Ranked Species

Species abundance hierarchy for 0.1m2 opening

plots in August 1966.

Fig. me

Species ranked by total per cent

cover found in 128 plots.

84

.9» anaaouwpa o
gamma cowonowwhe o
3.8ng aohwpnwm :
Rummage sweat a I
acuasnsa owmewooz
a . Abm neonxcp
o aHHomOpooa Nofisr

o , momohnfioo wow.

0 mwaouaamfiSepaw «Hmonns<

o spoon aHpraopom

o . mansopwpa mom

a .Qm mSQOfifiaoz

o anodes nophmopw<

. macnown wosuown
9 an? 3583

I scannhp m:£m_I

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.'

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‘-

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up
‘-
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p p - p L
A d 1 d u _
.u nu nu. 1.
nu nu 1i
nu 1.
1

po>oo anon nom.ddaoe

Ranked Species

Species abundance hierarchy for 1.0m2 opening

Fig. no

Species ranked by total per cent

plots in August 1966.
cover found in 50 plots.

85

‘-

10.9000

1000 -1-

‘-

4r-

100

encoumpa Esafiomuha
aopnowna wHHapaopom
opme5>AEsHmnwo
usasbao>noo Escowhaom

.gm mspoafiaoz a

035.0 Ego :50 Vegan. o
b

.. .mn .goanoohm I
. manage omwoavoz I
a Banana Koszm I

Hi gamma: .I

o uncomonsa mHHmmh£m_I

a manna£p_esommnho>.I

o «dachwamfisoppw «Hmonnfi¢ I
, . ammoamsoo mom I
womanhm damoflomsq I..

633303 K053» I

See.» aaawpcopom I

.mwmnopmpm mom I

owncowp wozpowq.u

endear? 25E I.
manage nonowapw I
made mugged?" I

uneasy nopsnoaM¢.I
aamnocwcwo aoaowwhw I

‘-

P p
1 a

1

10 4-

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L
A

0

Ranked Species

F180 0..

hierarchy for 10m2 opening
Species ranked b total per cent
§ plots.

(162 subdivision plots

f.
O.

gust 196

Species abundance
din 18

plots in Au
cover foun

86

‘-

109000

J-

1000 1 r-

apoanpu uwHaKo a
moawoppon «Haunnonom
asazbaopnoo Escowhaom

.pwb mwmnocmnwo monsowg o
. nousownm «Haaunopom o

noanwImonnfip wuamuom o ..

o agaouamgno Kasai I

a enemas 55.28.29 I

q .. mapwwazp «0.39:5 I.

o casewoCmo 890.28an I

0 .am sawfiomape I

o . 253.3 xofizm I

O ..H>m Euoggp .

s 02.8995 Esfifiomdfle II

a A? mspoazez. I

a _ enemas» Esomwnno> I

a cannon.” owmowuoz I

o . ammopQEoo mom I.

I. “Hfiomgood KQESM» 'I

o spoon waawpnepom I

o waaofiaaawfionnw wwmopoa<.u

mwmcopmna com I

mags «apnoea I

an? mgohn I..

define»? mg? I

ensues dophgonw¢.I

mange Gonomwhw I

uflanecmcmo nonmwdpw I

F b L
a d a
0

0 . 1
1..

1P-

-
1

qt—

100

9250 ”:00 some .7909

Ranked Species

Species abundance hierarchy for 1001112 opening

plots in August 1966.

Fig. p.

Species ranked by total per cent

cover found in 4(400 subdivision plots) plots.

87

..

.Qm aconnc> .

 

neboo 0:00 pom Adan?

apowapm anwKo o
anawaomaon aaaefisocnm o
. manuaw mwowp< c
cascaded Esoaflm o
eaamH5>AESHspHo e
monsomOLw wHprcOpom o
“HHowsa ommpcwam o
.Qm mwawcmp< . o
.Leb mannecwcmo monsomg a
wbwpwm owmowccE o
OHwGHOflmwo Esowxapwa o
esflaowwmsnpo sweat a .
. a>m Gaonxnb
o omdouwao esfiHOhfine
a .mfimuwao Kefiar
o mascoan sonuowq
o Momma cowomowwne
o . acaasmsfi owwowoez
o . mwflomwwmflfiepam “Hmonpfi<
o gopouocp mafiopm
o wHHcmouoem Knead
o mfimnocmaeo nonewfiafi
o mszccm Goaowflpw
mamas; :opzmosm<
. aDHw mwcnohq
o memondfioo mom
scwnahu mzflr
spoon waawucouom
mwmneuwpa mom
- - P p p . p P p .
a 1 . . q q q . q
m m m m 1
.. m
0
1

0 " I II I 'I I II I II I II I II I 'l I II ' II I I.

Ranked Species

Species abundance hierarchy for undisturbed fallow

Fig. q.

Species ranked by total per cent cover

.0
73
6t
90
11
p
m
um
J1
nun
.11
A.
8a
tan
kw
pr.

 

88

‘-

10:000

1000

db

100

onfihamw Snaawa

.Qm seasone>

camnfiaammoufivw998%nflm

.Qm Spacepow o

mpwHooocaH owwpnwam o

ESHH000HdHE mcHHw£o¢ a

eflammfiz> measnnmm o

oppchEmo_E:ficHnoq .9

mamannp Enomwnac> .

.mm acpm¢ .

quasapapce ccefiam a

asasbaoinoo as: omhaom .
L . . .
u q a

db

0 I 1
1

LO>OD ufioo how fldaofi

0 “L I II I.II I II I II I II I II I II I II I II I II

Ranked Species

Fig. q continued.

ofiscwouhho Esowanme
osfiamms ESwHec
cmccuwpa Esaaomwpe
mousewam waawpnopom
mSHs>Ho>coo sssowhaom
wfiwflaaapnm eGeHHm

cam ESwHOQwLB o
Esaflmmprm ESHLQE%mam o
mamas msuoawficzy o

wuwwaomaoa magmasomam .
mwcwficeem :socxsa. a
. mflccown wosuoag

89

‘-

10,000

.1-

1000

4L-

.4»-

100

ud-

«p

O .
1

AOwQE nomomowwae
sppmflm mwnwn¢
apowapm ansHo
wwaowawwwEepaw meOLQE¢
mGoomeDSQ mHHamhnm
a>m dsoqup

.mm mowcoae>
Sna0uoou masonm
mHHomouooe smear
mannaoscmo coacmflpfi
wzwflamu want

mucosa coh%aoaw<
waHSQSH omQOHUoE
ammoaasoo mom
mssccm Goacmflpm
snoop wHkucepom
gnaw mangoes
wamSoprm com

_ .
0 —

oi

1

pe>oo ucmo new ”duos

Ranked Species

bundance hierarchy for 0.1m2 opening

Species ranked by total per cent

Species a
er found in 128 plots

lots in June 1967.

Fig. r.

P
cov

90

“r

10,000

db

1000

.mm Escaaoahm
.Qu oweufiaom
msHS>Ho>coo endowmaom
wanmfiw mwnwnd
magmmas> woawpamm
.Qm awpsnca<
mswfioufimSpno Nessa
pmeE Gomoaowsae
.mwAOpmwmImmpsn sfiHemmwo
mammwao Nessa

9aw> mwmcepwnmo scanned a

0

9
m
9

0

I a

9 0‘90

1r

100
‘10,«-

‘-

Oeso

Q>m csonxcb
mammm£p_fizomwppo>
mascowp moppowg
emceumpa Sawaomaae
epOfinpm mflflmxo

.mm mafisopo>

wHHOkmewEopaw wflwoape<

manam mapoawaez
macacp Ezaaom«aa
Enhance» msfioam
mcfiHSQna owQOHpeE
mfimcepwcwo soaowwaw
wHHomOpoom KeEsm
eaflfiahp mast
spoon safiapsepom
ammoamEoo aom
msomea nonmmoam<
snag magnoaq

mfimCGpaam mom.

b p
a a

1

no>oo aceo pom fiance

O ‘L . .. I'II I II I II I II I II I II I II I II I II

Ranked Species

Species abundance hierarchy for 1.0m2 plots in
Species ranked by total per cent cover found

June 1967.
. in 50 pIOtS.

Fig. 3.

91

onwaamw Snufiso
onnwowmmo Esowxeawe

Ranked Species

 

Enownamaflb owwuawfim..
.Qm asflcwaom .
.Qm Romeo a
wnwnpawpcm onoflww .
T t. w n a . w w . + n
no nu nu Au. 1.
O 0 no 1;
m m 1 A
0 no>oo useo so.“ «upon.
1. .

0 " I II I-II I II I II I II I II I II I II I II I II

Fig. 3 continued.

92

‘-

10,000

.m-

1000

4|-

100

mnomwao Kossm a
onwawnw Enanew a
.Qn soanoao> o
awaewfis> moasnawm .

‘—

p
A

O .
1

o oasQwOAMMo Ezowxmasa

. A>m agonxcp
. oppsoaseo Ezaewaoq

moaflahm meflacfloe<
nasceflp eozuoeq
wpwflaomaem «Hpcflzoomm
mspfie appoHWHez
wanaaw massed

homes nomenommaa
omcoumpa EsaaomHae
sandman Ezomsnhc>
anOMHHmeouaw wwmoapsd
.am mwpmcoa¢
savanna efiflxxo
Essencep masonm
mceaoa_E9fiHomfiae
eCHHSQSH omeofipcz
mHmGeGQCmo :oaewflnfi
«Haemopoow,xefisr
czanamu wank

manage coaemflafi
emmcaQEoo mom
mwmfiepwam mom

snoop maaapCCpom
anHe nwcnohq

mamas; coahaoam<

—
d1 a

‘r-
y.

1

a¢>oo usco pom Hence

“ I II I'II I II I II I II I II I II I II I II I II

J

0

Ranked Species

Species abundance hierarchy for 10mg

plots in June 1967.

Opening
Species ranked by total per cent
. plots) plots.

subdivision

cover found in 18(162

Fig. t.

93

.1-

103000

.Qm nopm¢

EonsncmoncH Enfionnnemhnflo

easemensm mwammhxm

msHs>Ho>qoo Escommfiom

wcpcewae efiaaasopom

sawxnawpne encawm

.Qm Escapeahm

.ne> mamceoeceo sosuoeq

.Qm Ezwcwhow

.Qm cfiamnHpr

eneman> Esfiwafic

mafiaomfimspno Hefisr
omneunaa Snoanm .

--.._:,+--.... n L. ,1

‘F'
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O 1
1

1000

L¢>oo nice new ~d909

Au nv 1i

0 —b I II I‘Il I II I II I II I II I II I II I II I II

Ranked Species

Fig. t continued.

|
.1-

10.000

1000 4+-

mopcowam «fiaaunopom
BE £39..an .
.aa> mamderCco sosueeq a
Sawaoucaflwe ecHHfl£o< a
0 .nm wowcoao>
a mammeflp Esomsnao>
. aches nomonommne
. enumeoseo Enflpaaeq
e .Qm unexposeo
. sanwfim manead
o usamwao Nessa
. .an wwpecea<
o spewfiouaca wwawH30eQm
o Essence» eSanm
a cmccpman Esarouaae
c mfiaouwwmflsepaw mwmoanfid
. unseen Enwfloafiae
o mapfim szOHHHez
9 sandman moppowg
o mpowaum mfiasxo
o saaemoueom Keesm
. emmeaqfioo com
mwncepecwo :Daewflpw
swoon eHHHpCcpom
ecwflsmza cascapez
enafiahp mafia
mwmccpeam mom
manque coacwwpw
eDHm maCflbhA
anode; coahmoaw<

4r
«L-

. u p
q d -

n? 1.
1.

0 “L I II I’Il I II I II I II I II I II I II I II I II

100

ao>oo 9600 new Haas?

Ranked Species

Species abundance hierarchy for 100m2 opening

plots in June 1967.

Species ranked by total per cent

found in 4(400 subdivision plots) plots.

Fig. u.
cover

95

109000

ecfinaaque ocoawm
mascumwmIemasn manommeo
Snowcfimaab omwucSHm
wflaepwo encmez
mowwobaos mHHflpnepom
Hfiaemsa omspcwam
mflmn0>aw mflEenucd
caecflowpmo EgaanEhmwm
.Qm wflpeHHOpm
eczeawumaewafi> aflaepew
mwawwfis> sensppmm

.Qm Epofiaeahm
afiesfiowamo Esowxmawe

— b
d a

d
and-
‘0-

0 .
1

1000
100

ao>oo psoo new

990.

«p-

H1909

q-

0 ‘L I II I-II I II I II I II I II I II I II I II I II

Ranked Species

Fig. u continued.

APPENDIX C

PLOTS OF REGRESSIONS OF PER CENT COVER OF

MAJOR SPECIES OCCURRING IN AUGUST 1966 ON

THE PER CENT COVER OF AMARANTHUS RETRO-

 

FLEXUS THAT HAD OCCURRED IN THE SAME

PLOTS IN AUGUST OF 1965

97

 

1004-
904.-

:3

a 30"

H +

£0 70..

32

a

g 60"”

0

E31

g 50‘?

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as

g 40--

‘4

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O 0

O

.p

5 ac» .

0 ' .

S

m 10» .

. .

 

i0 20 30 40 50 60 70 80 90 1

 

Per Cent Cover of Amaranthps
retroflexus in AuEfiat‘TSES.

Fig. a. Regression of per cent cover of Pea compressa in
Aug. 1965 on per cent cover of Amaranthus retroflexus in

Aug. 1965 on 128 0.1m2 openings out in a first year Tallow
field. . .

 

 

98

 

1004-
“, 90~~
(O
O)
H

. 80‘-
2? L
a:
G5 70...-
H
H
3
o 60‘-
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0
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‘< ‘50‘*
N
O
5
a, 40--
L.
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O .
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.. .0 o '. . °

 

 

. O
l l L l ' I
W T , I r I H

I
io 20 so 40 so so 70 so so 100

Per Cent Cover of Amaranthus
retroflexus in August 1965

Fig. b. Regression of per cent cover of Rumeg acetosella in
Aug. 1966 on per cent cover of Amaranthus retrofiexus_1n
Aug. 1965 on 128 0.1m2 openings cut‘in a first year fallow
field.

 

 

99

I

1004

90......

70‘...

 

 

Per Cent Cover Potentilla recta Aug. 1966

 

 

:Ie 4H.
i0 20 30 40 50 60 70 80 90 1 0

Per Cent Cover of Amaranthus
retroflexus in August Iggo

Fig. 0. Regression of per cent cover of Potentilla recta in
Aug. 1966 on per cent cover of Amaranthus retroflexus in
Aug. 1965 on 128 0.1m2 openings Efit in a first year fillow
field.

 

100

1004-
90‘-

80-~°

 

S

20 “on.

 

Per Cent Cover Erigeron annuus Aug. 1966

 

: § 5 i. i '% ¢—-{
io 20 so 40 so so 70 so so 100

 

Per Cent Cover of Amaranthus
retroflexus in August 1965—

 

F18. d. Regression of per cent cover of Erigeron annuus in
.Aug. 1966 on per cent9 cover of Amaranthus retroflexus in
Aug. 1965 on 128 0.1m2 openings out in a _f1rst year Iallow
fiCld.

 

 

 

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Per Cent Cover of Amaranthus
retroflexus in August ISSST

Fig. e. Regression of per cent cover of Poa_p3atensis in
Aug. 1966 on per cent cover of Amaranthus retroflexus in
Aug. 1965 on 128 0.1m2 openings out in a‘fTFst year‘rallow

field.

 

 

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Per Cent Cover Lactuca biennis Aug. 1966
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Per Cent Cover of Amaranthus
retroflexus in August 1965—

Fig. f. Regression of per cent cover of Lactuca biennis in
Aug. 1966 on per cent cover of Amaranthus retroflexus in
Aug. 1965 on 128 0.1m2 openings cut in a first year fallow
field.

 

 

 

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Per Cent Cover of Amaranthus
retroflexus in August 1965—

 

Fig. g. Regression of per cent cover of'Lychnis EASE in
Aug. 1966 on per cent cover of Amaranthus retroflexus in

Aug. 1965 on 128 0.1m2

field .

openings cut—in 5 first year fallow

104

 

 

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Per Cent Cover of Amaranthus
retroflexus in August 1960

Fig. h. Regression of per cent cover of‘Erigeron canadensis in
Aug. 1966 on per cent cover of Amaranthus retroflexus in~

AUS- 1955 on 128 0.1m2 openings cut in a first year fallow
field.

 

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