Table Of ContentEcology
of the
Northern Lowland Bogs
and Conifer Forests
James A. Larsen
University-Industry Research Program
University of Wisconsin
Madison, Wisconsin
ACADEMIC PRESS
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Library of Congress Cataloging ia Publication Data
Larsen, James Arthur.
Ecology of the northern lowland bogs and conifer
forests.
Includes bibliographical references and index.
1. Bog ecology—United States. 2. Bog ecology—Canada.
3. Forest ecology—United States. U. Forest ecology—
Canada. 5. Conifers—United St at e s-«—Ecology. 6. Conifers
—Canada—Ecology. I. Title.
QKL0U.L3U 1982 58ΐ.5,2β325 82-11368
ISBN 0-12-U36860-3
PRINTED IN THE UNITED STATES OF AMERICA
82 83 84 85 9 8 7 6 5 4 3 2 1
Preface
It is a warm afternoon and the bright sun is setting in a cloudless sky. The few
resident ducks sit quietly on a pond just visible in the distance. A marsh hawk has
drifted past over sedges emergent in a shallow slough, the water rippling in the
gentle breezes. The peace is so absolute it is almost unimaginable.
One is inclined to feel, against better judgment, that this placid scene will be
perpetuated forever. It will, however, be broken in a day or a week by harsher
winds and flights of migrant ducks. Wedges of geese will sweep in from the north.
The idyllic Elysium will turn boisterous, the tamaracks will shade into brilliant
gold. The spruces will be a black onyx set into the backdrop of higher hills beyond
the bog. Both bog and adjacent marsh will be covered with a drifting of fallen
leaves over dried sedges.
This is a book on the ecology of bogs and conifer swamps and, to some extent,
the marshlands. An appreciation of bog and marshland ecology is as much an
esthetic experience as is the perception of bog sights and sounds during the
seasons of the year. To a scientist, there is an esthetics of science, just as to a com
poser there is a science of musicology. Often, sensuous appreciation of nature
precedes intellectual maturing and fascination with the sciences.
The chapters that follow are, for the most part, a review of what is known
about the northern bogs and lowland forests, written in the terminology of
science in the hope, as well as the expectation, that such knowledge will be of
value to those who appreciate the beauty of bogs and marshlands, to ecologists
and other biological scientists, naturalists, wildlife conservationists, hunters,
trappers, construction engineers, as well as to others whose vocations or avoca
tions take them afield.
The discussion is devoted, at least primarily, to the ecology of one kind of
wetland—the lowland bogs and conifer forests—and treats only in passing the
marshlands and other kinds of vegetational communities that are also classified
as wetlands. In general, the former can be distinguished from the latter by the
presence in lowland bogs and conifer forests of the Sphagnum mosses and by ac
cumulations of peat. The bogs and conifer forests are, therefore, known also as
peatlands, but the distinction between the two kinds of communities—peatlands
and marshes — is not always clear to the unpracticed eye.
A quick view of the northern landscape will, moreover, usually reveal that
marshes, lowland bogs, and conifer forests are intermingled, and that these com
munities all grade into one another so that it is difficult to decide where one
begins and another ends. We are concerned, however, with the lowland peat bogs
and forests, particularly those that have developed to a point where their identity
ix
X Preface
is indisputable for the simple reason that no other review of accumulated knowl
edge on these vegetational communities is presently available. Many books, arti
cles, and research papers have been written on the marshlands, much fewer on the
lowland bogs and conifer forests. This is perhaps because the marshlands are of
value to hunters and trappers and all who are interested in wildlife. The marshes,
too, are in most cases more accessible—a person can travel to them or through
them easily by boat. The bogs and conifer swamps, on the other hand, are hard to
get to, and even more difficult to get through—one must walk, and the walking is
not easy, since feet sink into wet moss and peat at every step and the sense that
one is mired is unsettling to say the least. Hence, the bogs and conifer forests have
not been studied very much. By now, however, the importance of bogs and coni
fer swamps, in regions where they are found, is becoming more deeply appre
ciated, and research has expanded greatly and has begun to catch up with work
on marshes in recent years.
Wetlands were once valued only as wildlife habitats or as areas of potential
value for agriculture, highways, or buildings. The high intrinsic value of natural,
undisturbed wetlands for ground water replenishment, flood control, as well as
wildlife habitat has led both federal and state conservation agencies to enact pro
tective legislation and to acquire wetlands for wildlife sanctuaries and for storage
basins that insure continued supplies of water for lakes, rivers, and wells. The
result has often pitted private gain against public good, but growing official con
cern and public awareness has given wetland conservation an impetus lacking in
early days.
Even so, the Great Lakes Basin Commission estimated that 20,000 acres of
Great Lakes Basin wetlands are drained or filled each year. No exact figures are
available on the proportion of original native wetlands that now have been con
verted for other purposes, but nationally the figure is thought to range between
30 and 40 percent. In Wisconsin, figures exist to show that only about 25 percent
of the original wetlands now remain in what might be considered an undisturbed
condition, although some disturbance has, of course, occurred in all of them dur
ing the past century.
The lowland bogs and conifer swamps, which together form the peatlands, are
usually adjacent to, or at least near, marshes and sloughs that provide food,
shelter, and breeding ground for waterfowl, mink, and muskrats, as well as for
other mammals such as raccoons and white-tailed deer. The peatlands store water
that maintains adequate levels in the spawning grounds of walleye and northern
pike, muskellunge, trout, perch, and other fish species. The lowland bogs are
probably the only native plant community that is cropped extensively, and this
for cranberries, of which Wisconsin and Michigan are the nation's top producers.
This use does not seriously conflict with some of the other useful functions of
bogs, such as water storage and control of sediment carried by runoff from sur
rounding uplands. Much commercially valuable timber is also found in the low
land forests—tree species such as northern white cedar and black spruce.
Preface xi
Regional economists have said that it is difficult to put an accurate price tag on
any of the values that wetlands possess, but it is now clear that the preservation of
the remaining wetlands may well prove vital to the environmental and economic
well-being of the Great Lakes region as well as to areas where the lowland bogs
and conifer forests may be found, among which are the Pacific Northwest,
British Columbia, Alaska, central Canada, New England, and the Maritime
Provinces.
It is my hope that the environmental and economic value of the northern
lowland bogs and conifer forests, as well as an appreciation of the esthetic and
scientific values of the research conducted there, will be communicated to those
who read this book.
James A. Larsen
1 Lowland Bog and Conifer Forest
Ecology: Historical Perspective
Looking back over the history of ecology in the United
States—not in any systematic way but as revealed in a casual
reading of a few issues of old botanical journals—the sur
prising thing is not that the material seems so old, but that
it seems so new.
There have been no great revolutions in ecological thought.
There have been refinements, more detailed observations, and
now, recently, mathematical treatment of data and principles,
but on the whole the basic foundations of ecology laid down as
long as a century ago still stand.
It is significant that this should be the case. The same
is true of all fundamental sciences—chemistry and physics, for
example—in which underlying foundations established in the
eighteenth and nineteenth centuries remain largely intact.
This is only applicable, of course, to events at the level
scientists were capable of studying at the time: events that
can be made to occur in flasks and test tubes or that can be
observed in nature, not the subatomic phenomena more recently
studied with the use of an array of powerful instruments avail
able to modern scientists.
The same cannot be said about the so-called soft sciences.
The views held today about the nature of reality in psychology,
sociology, behavior—if these can be called sciences in the
true sense—are in many ways modified substantially from what
they were at the turn of the century.
The point is that ecology does, indeed, seem more closely
allied to basic sciences than to social sciences at least in
these respects, although much ecological research employs stat
istical methods used in social sciences, such as factor analy
sis and principal component analysis, which rarely find use in
basic sciences.
All of this is prelude to what, to me, are some surprising
ly modern statements made in the early botanical papers deal
ing with the forests of the Upper Midwest—the western Great
Lakes region—found in journals dating to the late years of
the nineteenth and the early years of the twentieth century.
1
2 Lowland Bog and Conifer Forest Ecology
Ecology now encompasses an astonishing breadth of subject
matter, with as many narrowly specialized subfields as any
other science and so the discussion here must necessarily be
narrow and specialized. Since we are dealing with the vege
tation of an area in the Upper Midwest, it will concern one
field—the ecology of plant life. It will concern one aspect
of the plant life of this region—the native vegetation of
parts of Michigan, Wisconsin, Minnesota, and Ontario within
the Lake Superior watershed or, in some instances, the upper
Mississippi River, and specifically the vegetation of the low
land bogs and conifer forests.
Ecology is concerned with relationships between living
things and their environment. For a hint of what this defini
tion means in terms of vegetation, we can take an example from
an early ecologist who studied the forests of the Great Lakes
region. In an essay on the forests of northern Michigan, Whit-
ford (1901) wrote that the purpose of his study was to answer
some of the questions involved in the development of forests:
In other words, the question is, why are there forests
on certain physiographic formations and none on those which
lies close by? Also within the forest itself there predomin
ates now one and now another tree type. In some places the
coniferous forest is prominent, in others the maple-beech-
hemlock type is the chief feature. Indeed, if enough re
gions are studied an indefinite number of combinations may
be observed. Thus not only must the presence or absence of
trees be explained, but also where trees are present a reas
on must be given for the dominance of any particular kind of
forest. If these questions can be answered satisfactorily,
some light will be thrown on the origin and development of
forests. In the answer three sets of factors are involved,
climatic, ecological, and historical.*
FOREST INFLUENCES
Whitford described in more detail than we need be concerned
with here the influence of the various environmental factors
upon the vegetation that covered the landscape, using familiar
phrases that can be found without major modification in mean
ing in recent publications on plant ecology:
By atmospheric factors are meant those which influence
the aerial parts of plants. They include radiant energy in
the form of heat and light, and also the influence of
wind...
* Reprinted by permisssion of The University of Chicago Press.
Ecology of the Northern Lowland Bogs and Conifer Forests 3
Once a dense forest is established, all forms of low
vegetation, except those species that have special shade
adaptations, are driven out...
Again, the struggle may be between plant societies, as
the forest and heath, or forest and prairie. The line
along which two societies meet has been called the tension
line. If the other ecological factors remain the same, the
tension line does not change...
Not only may the struggle be between the forest on the
one hand and some other type of plant society on the other,
but it may be between different kinds of forests...
The three great physical media—soil, air, and water—
are all influential in bringing about certain plant societ
ies. These, together with the biotic factors, make that
variety in the landscape of any region which is shown in
the plant societies that are present...
Since trees present a greater transpiration surface than
other forms of plants they must occupy those positions where
there is sufficient water to maintain the transpiration
current. This excludes them from regions where the water
content of the soil approaches the minimum; a stagnant con
dition of soil water is likewise injurious to trees...
The physical properties of the soil play an important
role, for upon them depends the capacity of the soil to
hold water...
The greater part of the eastern half of the United States
is a potential forest. Here the two great climatic factors,
temperature and moisture, are favorable to the development
of forest trees...
Within this vast forest formation there are prairie,
beach, dune, heath, swamp, and other plant societies; also
the forest itself may be divided into a number of different
forest societies...*
As a demonstration of the fact that these same general
topics are those that concern ecologists at the present time,
here are a few of the topical divisions of a modern ecology
textbook (these are subheads within one section of the volume):
"Light as an environmental factor," "The distribution of moist
ure within vegetation," "Air movement above the ground and with
in vegetation," "The soil environment," "Nitrogen supply." One
author of a recent volume on physiological plant ecology (Ban
nister, 1976) summarizes the contemporary view by stating that
"physiological responses to specific environmental variables
can provide at least partial explanations of ecological pheno
mena. " He adds that the variables together "form a picture of
the whole complex of plant-environment relationships which
constitutes plant ecology."
* Reprinted by permission of The University of Chicago Press.
4 Lowland Bog and Conifer Forest Ecology
DISCOVERY OF THE PRINCIPLES
The birth of what we now accept as the fundamental princi
ples of ecology somehow seems to lack the drama and intensity of
purpose that marks the great discoveries of chemistry and physics,
but the parturition in each instance must have been preceded by
an intuitive insight, and a feeling of profound rightness, on
the part of the participants, just as Newton must have had and
just as was evidently the case for Einstein with his concept of
relativity. This kind of inspired flush of comprehension has
been described by Keynes as the product of intuition, and he says
of Newton that "his pre-eminence is due to his muscles of intui
tion being the strongest and most enduring..." The same must be
true, in perhaps lesser degree, of the botanists who saw that
plants have not been placed over the face of the earth by some
working of divine will, but rather by the influence of the en
vironment. This was not always the accepted view; and the his
tory of birth, denunciation, and final acceptance lies deep in
the past, as the history of science goes, just as does the his
tory of Newton's formulation of the principles that bear his name.
In describing these origins, a noted figure in the history
of American ecology, Cowles, wrote as follows in 1911:
The earliest account which I have discovered that clearly
deals with vegetative dynamics is in a short paper in the
Philosophical Transactions in 1685, in which William King
gives a good account of the origin of bog vegetation from
floating mats; many times since, this has been reported as
an original discovery. Perhaps the first to have a real
glimmer of the doctrine of succession, as understood today,
was the great French naturalist Buffon. Although better
known for his spendid descriptions of animals, Buffon in his
earlier life was much interested in forestry, and 1742 he
noted that poplars precede oaks and beeches in the natural
development of a forest...Biberg, a student of the great
Linnaeus, published his thesis in 1749, and in this he des
cribes the gradual development of vegetation on bare rocks;
here he observes accurately the pioneer activity of the
lichens and mosses, and he notes as well the importance of
Sphagnum in the development of bogs.
The seeds planted by Buffon and Biberg fell on sterile
soil; in France it was observed that Buffon was trespassing
on theological grounds, and he was obliged to recant any
views which implied that the world was not made in the
beginning once for all; in Sweden the influence of Linnaeus
was wholly against anything dynamic; he never published
anything dynamic himself, and when a student like Biberg
set his face in that direction, the master frowned, and
said that the student was departing from the true mission
Ecology of the Northern Lowland Bogs and Conifer Forests 5
of the botanist. It is not strange, therefore, that there
followed a sterile period of three-quarters of a century.*
Although Buffon was obviously speaking of succession in
his publication on plant communities in 1742, it was not un
til 1806 that the term came into use to mean the sequential
development of a community through a series of prior stages.
In the latter year, a botanist named De Luc wrote:
The bottom of every dale is a meadow on a subsoil of
peat; this, by gradually advancing into, contracts the
original extent of the lakes; and, it was well-known...that
many large lakes have been converted into smaller ones, by
the peat advancing from the original shores, and in many
places now meadows, and only traversed by a stream, had
still a lake in them, in the memory of old people...The
succession of these different zones, from the border of
water towards the original border of sand, represents the
succession of changes that have taken place through time
in each of the anterior zones...
It was Huit, however, who was evidently the first to fully
recognize the fundamental importance of successional develop
ment in plant communities. He studied the forested land of
Blekinge, Finland, and in 1885 traced the succession of each
stage, seeing that grassland became heath, that the heath de
veloped into forest. The early stages of forest development
were dominated by birch, and on dry soil this is followed by
pine, on wet soils by spruce. A birch forest can also be re
placed by oak forest, which then develops into a beechwood. In
swamps, the succession goes from mosses to sedges to a moor
vegetation to birch and finally to a spruce forest.
These faint beginnings, in the dim distance of a century,
still possess some surprisingly modern aspects. So, too, do
the works of Humboldt and those also of Warming, who in 1895
published his "Oecology of Plants." In 1898, Schimper pub
lished "Plant Geography on a Physiological Basis," translated
from German into English in 1903. Cowles published his classic,
"The Ecological Relations of the Vegetation on the Sand Dunes
of Lake Michigan" in 1899, followed in 1901 by "The Physio
graphic Ecology of Chicago and Vicinity."
EARLY AMERICANS
Cowles has already been mentioned, and he stands today as
one of the great hulking figures in early American plant eco
logy, standing beside—but slightly apart from—Clements, of
whom we speak today in perhaps somewhat awed but not entirely
sympathetic terms. Of Cowles there is not much to be said,
*Reprinted by permission of The University of Chicago Press.
