Prospectus for a book
How Should a Clever Moose Eat?
Subtitle: And Other Questions an Ecologist Asks
John Pastor
Professor
Dept. of Biology
University of Minnesota Duluth
Duluth, MN 55812
jpastor@d.umn.edu
218-726-7001
Ecologists often ask questions that most people consider, well, peculiar. Such as: How should a
clever moose eat? When I once told my sister, who is not a scientist, that this was the question I was
working on at the time, she looked at me and said: “Anyway it wants to. Why should you care?” This is a
very good question. The purpose of this book is to explain why my sister and other people who aren’t
scientists, as well as people whose interests are piqued by such questions, should care.
The focus of this book will be the North Woods, which stretch from Minnesota to Maine and
north to Hudson’s Bay. The North Woods are one of the most ecologically, geologically, and aesthetically
interesting places on earth. The North Woods of Minnesota at the western end of Lake Superior is where I
live, do research, and teach. Here, the glacial deposits from the Ice Ages lie atop some of the oldest rocks
on earth and support northern hardwoods and boreal conifers. Here, we find moose and beaver, the
highest diversity of birds north of Mexico, and insects with spectacular population dynamics such as
spruce budworm and tent caterpillar.
This is a very beautiful forest, especially in autumn when the intense red and yellows of
deciduous trees contrast with the deep blue-greens of the conifers. As I write this, people are making their
annual trip to the North Woods to see the autumn colors, but I would guess that many of them don’t think
about why leaves change color or what happens to leaves after they fall. While an understanding of leaf
abscission and litter decay is not required to see beauty in the North Woods, it can certainly deepen one’s
appreciation of it. And this deeper scientific understanding does not make the North Woods less beautiful.
In this book of essays, I hope to enrich reader’s understanding of the beauty of how Nature
works. These essays explore the natural processes of my northern home, how these processes change
across seasons and over years, and our roles in these changes. The common threads through these essays
include how the physical environment constrains ecological processes, how species of the North Woods
interact with each other and the landscape, how evolution by natural selection modifies these interactions,
and how scientists discover how the natural world works. The excitement of science lies in asking
questions and, in trying to answer them, discovering even larger questions we didn’t know enough to ask
when we began. I always tell my students not to worry if their first hypothesized answer to a question
doesn’t pan out or even if the question itself is abandoned. In the end, Nature is always more interesting
than we originally thought.
The ecological interactions at particular places take place among specific species and among
species and their physical environment. To understand these interactions one must begin with a question
rooted in natural history. It is my firm belief that all good ideas in biology begin with a question in natural
history. For example, I have spent much of the past 30 years trying to answer the questions: Why did the
moose eat this plant and not that one, and what difference does it make? and Why did the beaver choose
to build a dam here and not there? A question in natural history must be answered within the context of a
particular place. Each essay in this book will begin with a question or observation about the natural
history of a particular place in the North Woods or an organism which inhabits it, then proceed to larger
questions and conclusions about how Nature works in general.
The North Woods played a major role in the development of the modern quantitative science of
ecology. Our modern ideas of forest succession, the role of forest fire, responses of forests to climate
change (both past and future), how watersheds work, how herbivores such as moose and beaver engineer
their habitat, the relationship of a predator to its prey, how species avoid competition, and many other
ideas in ecology began by asking questions about the natural history of the North Woods.
The fundamental idea of ecology which emerged from studies of the natural history of the North
Woods is that changes in one species’ population are amplified through the food web and affect other
species, the cycling of nutrients, the flow of water, and the productivity of the ecosystems. There are
fewer species in the North Woods than in tropical forests, but each species does something very different
than the rest. Consequently, changes in one species here are very quickly translated into large changes in
the ecosystem and landscape. We are just now beginning to learn how the natural history of species and
the feedbacks which link them into food webs amplify small changes in climate or harvesting, resulting in
large and rapid changes in the state of northern ecosystems. But many questions remain open. These open
questions are the grist for tomorrow’s research by today’s undergraduate and graduate students.
Besides being the source of many of our ideas on ecology, the North Woods is the theater upon
which much of the American character has emerged while we have been extracting resources from it. On
the western shore of Lake Superior at the border between Minnesota and Ontario is a set of rapids, around
which the voyageurs lifted their canoes and cargo along the Grand Portage on their way to the forests of
the North Country in search of beavers. The fur trade of the 1600s and 1700s inserted us squarely into the
ecology of the region and almost caused the extinction of beaver, moose, lynx, wolves, and other species.
The French and Indian Wars were fought throughout the North Woods from Maine to Lake Superior
partly in order to determine whether the British or the French controlled the fur trade.
Our presence in the North Woods continued through the harvesting of the large pines beginning
in New England, continuing through New York, Michigan, and Wisconsin, and ending in Minnesota.
The pine harvest and the subsequent harvest of other tree species once the stock of pine dwindled set into
motion a chain of natural events that continues today, including changes in the fire regime. In addition,
extraction of iron and other minerals forever altered entire landscapes in northern Minnesota, the Upper
Peninsula of Michigan, and Ontario.
The harvesting of timber and furs and extraction of iron from the North Woods were the
economic foundations for the growth of cities near its the southern edge, such as Duluth, Detroit,
Chicago, Cleveland, Milwaukee, and Minneapolis, among many others. As we became more urban, we
grew increasingly estranged from nature and how scientists learn about it. Yet, scientific issues underlie
many of our legislative problems today, including global warming, the sustainable harvesting of
resources, the control of predators and insects, and the preservation of species. Our estrangement from
nature and how scientists learn about it only breeds more estrangement. It is a self-amplifying feedback
that continually erodes our ability to develop sound economic and environmental policy.
Our decisions on how we wish to care for the earth can only be enhanced by recovering a
fascination with how nature works. As Robert Michael Pyle has said, “What we know we may choose to
care for. What we fail to recognize, we certainly won’t.” I firmly believe that if people could know,
really know, what beautiful, living, working systems lakes, rivers, and forests are, they would do
everything they could to preserve them. Causing the extinction of a species should seem a crime equal to
the defacing of the Mona Lisa or the Pieta.
When I think of the North Woods, six big ideas come to mind. These will be the main organizing
sections of the book (see Annotated Table of Contents). First, the North Woods is a land sculpted by
water, snow, and ice. All organisms must adapt to the overriding control of water in all its forms. The
ecology of North Woods organisms, especially that of beaver and peatland plant species, in turn controls
the distribution and flow of water. Second, there is a striking diversity of crowns of different tree species,
which is the basis for the spectacular beauty of this forest. The purpose of a crown is of course to capture
light and produce plant biomass, but why is there this striking diversity of crown geometries, leaf shapes,
and leaf lifespans? Third, although the food webs supported by production of plant biomass are very
simple, they contain strong interactions between the animals which eat the plants and eat, compete, and
cooperate with each other. These strong interactions often result in extreme population cycles such as
between lynx and hare or moose and wolves. These extreme population cycles are a hallmark of northern
ecosystems. But if widely oscillating populations imply great instability, how can these populations and
even the North Woods persist? Fourth, the plant species of the North Woods have evolved a remarkable
variety of berries and seeds in order to disperse their genes across the landscape and to the next
generation. Many of these seeds and berries are highly edible (such as blueberries), which implies a
coevolution between seed producer and seed eater. How does this coevolution work to the benefit of both
seed producers and seed consumers? Fifth, even without the presence of humans, the North Woods is a
theater of large and catastrophic disturbances, most notably fire. Some species such as sugar maple are
killed outright by fire, but others such as jack pine require fire to open their cones and disperse their
seeds. How does a forest reorganize itself after fire? How does fire move through a landscape previous
fires have shaped? And sixth, humans, especially Europeans, have been and are now a major shaper of the
North Woods, beginning with the fur trade, continuing through the extraction of resources, and extending
into the future with climate change. The North Woods species did not coevolve with humans, but clearly
how they respond to us (and we to them) will determine the future of the North Woods. How can we use
natural history to better inform management and policy? Will the North Woods survive global warming
intact or will warming cause its disassembly?
These six sections which explore these ideas will not be independent, stand-alone blocks but will
be linked by common ecological concepts whenever possible. To give an example of how this will be
done, I’ve included a Partial Concept Map of the Book Chapters. This concept map illustrates how
concepts and ideas introduced in each section are taken up in later sections in different contexts. I’ve
selected the attached essays to illustrate how this structure might work. These essays span the full breadth
of all these sections. The Birth and Death of a Beaver Pond is about how beavers interact with their
glaciated landscape to control the flow and chemistry of water and how this control changes as the pond
matures, is abandoned, and succeeds to a wet meadow. Foraging in a Beaver’s Pantry describes how
beavers choose which trees to cut to maximize energy intake and how this dietary choice alters the
species composition of the surrounding forest. This essay and How Long Should a Leaf Live? both lead to
the title essay, How Should a Clever Moose Eat?, which explores how beaver clearings and leaf chemistry
affect a moose’s diet and foraging strategy, and to Mouse Wars, Fungi, and Spruce, which explores how
voles and fungi determine when and whether spruce invades abandoned beaver meadows. Finally, all of
these essays on the interactions between beaver, moose, voles, hydrology, and the natural history of the
major tree species lead to my favorite northern ecologist in David Thompson’s Canoe. Thompson
explored the North Woods from Hudson’s Bay through Minnesota to the Pacific Ocean for the Hudson’s
Bay and Nor’West fur-trading companies. His journals contain many questions in ecology and natural
history which remain unanswered even today. This progression of ideas through different sections of the
book are also examples of how good research questions on the natural history of a species lead one in
unexpected directions and to larger issues.
These and other ecological concepts will be explored in other essays and sections. For example,
the importance of leaf chemistry, first introduced in How Long Should a Leaf Live?, will reappear in How
and When Should Leaves Die?, The Ups and Downs of Wild Rice, and Climate Change and the Past and
Future of the North Woods. To help me bring out these ecological concepts, I will create similar concept
maps as the book proceeds. These concept maps will help me plan, link, and revise essays when necessary
to provide threads to guide the reader through the book.
Each essay will be somewhere between 1500 and 2500 words, about the length of this prospectus.
I have drafts of about 20 of them written already and plan to complete about 10 – 15 or so more, for a
total book length of approximately 60,000 – 80,000 words (see attached annotated partial table of
contents). A section of suggested readings will give the citations of the papers and books mentioned in the
essays as well as other works of interest to readers who wish to explore the topics further. Specific
references to papers will be included in end notes to each essay.
The intended audience for this book is anyone interested in learning more about ecology in
general and the natural history of the North Woods in particular, from undergraduate and graduate
students searching for a research problem to interested members of the general public. The open questions
discussed in some of the essays might be possible research problems for undergraduates and graduate
students, or even my own colleagues. Citizen Science organizations and activities often center on
questions in natural history and ecology of a particular place. This book might serve as source of ideas for
Citizen Science projects or for book clubs sponsored by local conservation and natural history
organizations, such as Audubon chapters.
The past several years have seen a resurgence of interest in natural history. The Ecological
Society of America has recently added a Natural History Section; members of that section as well as
others subsequently initiated The Natural History Network (I am a member of both organizations). The
Natural History Network would be a good outlet for bringing the book to the attention of natural history
educators and ecologists. I will submit an essay to the Journal of Natural History Education Network
exploring some of the ideas in this book (perhaps a version of the introductory essay). The Journal of
Natural History Education has recently published an essay by Gordon Orians in advance of his
forthcoming book on the aesthetic roots of natural history
(http://naturalhistorynetwork.org/journal/articles/the-aesthetic-roots-of-natural-history/). I would be
pleased to work with Island Press to reach the same audience as readers of these books and the scientists
and natural history educators of the Ecological Society of America and the Natural History Network, and
the general public.
I am also an artist and sometimes teach a class in biological illustration. I plan to illustrate about
one third or half of these essays with pen-and-ink drawings, several examples of which are included
which would accompany the essays How Long Should a Leaf Live? (aspen and red pine), Everybody’s
Favorite Berries (blueberries), and Tent Caterpillars, Aspens and the Regulation of Ecosystems (tent
caterpillars). More examples can be found at http://www.projectartfornature.org/Main/Pastor.html.
Drawing and painting the North Woods helps me dive deeply into what makes them so visually beautiful.
Deep down, science and art are two expressions of the human need to find beauty.
I hope in these essays to introduce the reader to the surprises uncovered by scientists working in
northern regions, as the research being done on these ecosystems is some of the most exciting in all of
natural science. In reading these essays, I hope the reader will get a sense of how scientists think (there
are many scientific methods, not just The Scientific Method) and how scientists approach the natural
world (on all fours and in awe when things are going right). I firmly believe that education about how the
natural world works is the best way to move forward to address our environmental problems. Perhaps a
deeper understanding of how our forests, streams, and lakes work will make us a force for the better in
our natural environment.
Partial Concept Map of Book Chapters
Introduction: The Natural History of the North Woods
A Landscape Sculpted by Water and Ice
Hydrology and Beaver Ecology
Sculpting a Landscape
The Power of Moving Water
The Birth and Death of a Beaver Pond
Seas of Muck
Ice
Evergreen/deciduous
Capturing the Light
How Long Should a Leaf Live?
The Shapes of Leaves
The Shapes of Crowns
Tolerant of Shade or Rapid Growth in Sunlight?
How and When Should Leaves Die?
Foraging and Food Webs
When Should Flowers Bloom and Fruits Ripen?
Everyone’s Favorite Berries
Skunk Cabbages, Blowflies, and the Smells of Spring
Mouse Wars, Fungi, and Spruce
The Ups and Downs of Wild Rice
Crossbills and Conifer Cones
Fire and the Dynamics of a Landscape
Does Fire Destroy or Maintain the North Woods?
A Fire at Little Trout Lake
The Ham Lake Fire, Several Years Later
Humans and the North Woods
David Thompson’s Canoe
Does Clear-cutting Mimic Fire?
White Pine, Douglas-fir, and Old Growth Management
Climate Change and the Past and Future of the North Woods
Fur trade
Fur trade
Pollinators, Fruits, Seeds, and Seedlings
Foraging
Tent Caterpillars, Aspens, and the Regulation of Ecosystems
Foraging in the Beaver’s Pantry
The Diversity of Warblers and the Control of Spruce Budworm
Snow, Lemmings, Moose, and Wolves
How Should a Clever Moose Eat?