Ecology of North America

Brian R. Chapman, Eric G. Bolen

• Publisher: Wiley
• Year: 2015
• Print ISBN: 9781118971543
• eBook ISBN: 9781118971567
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

North America contains an incredibly diverse array of natural environments, each supporting unique systems of plant and animal life. These systems, the largest of which are biomes, form intricate webs of life that have taken millennia to evolve. This richly illustrated book introduces readers to this extraordinary array of natural communities and their subtle biological and geological interactions.

Completely revised and updated throughout, the second edition of this successful text takes a qualitative, intuitive approach to the subject, beginning with an overview of essential ecological terms and concepts, such as competitive exclusion, taxa, niches, and succession. It then goes on to describe the major biomes and communities that characterize the rich biota of the continent, starting with the Tundra and continuing with Boreal Forest, Deciduous Forest, Grasslands, Deserts, Montane Forests, and Temperature Rain Forest, among others. Coastal environments, including the Laguna Madre, seagrasses, Chesapeake Bay, and barrier islands appear in a new chapter. Additionally, the book covers many unique features such as pitcher plant bogs, muskeg, the polar ice cap, the cloud forests of Mexico, and the LaBrea tar pits. "Infoboxes" have been added; these include biographies of historical figures who provided significant contributions to the development of ecology, unique circumstances such as frogs and insects that survive freezing, and conservation issues such as those concerning puffins and island foxes. Throughout the text, ecological concepts are worked into the text; these include biogeography, competitive exclusion, succession, soil formation, and the mechanics of natural selection.

Ecology of North America 2e is an ideal first text for students interested in natural resources, environmental science, and biology, and it is a useful and attractive addition to the library of anyone interested in understanding and protecting the natural environment.

CHAPTER 1
Introduction

In all things of nature there is something of the marvelous.

Aristotle

Think big for a moment. Imagine a transect running north to south, stretching across the midpoint of pristine North America in the year 1500. We will use the 100th meridian, which traces the right-hand edge of the Texas Panhandle, as our line of travel. At its northern end – the North Pole – the transect begins in a desolate cap of ice and snow and then crosses a vast Arctic landscape of tundra before traversing a wide band of spruce and fir known as the Boreal Forest. Wolves howl in the distance; the scattered remains of their most recent kill – a sickly moose – lie still fresh atop the deep snow. South of these dark forests spread the plains, grasslands grazed by millions of bison and even larger numbers of prairie dogs. After leaving the plains, our excursion takes us across the narrow, clear rivers and low hills of the Edwards Plateau before dropping into a region studded with low, thorny trees. The transect ends, for our purposes, when it reaches northern Mexico and the yucca-spiked Chihuahuan Desert.

A similar transect running east to west across the waist of North America at first encounters the sandy beaches and dunes of the Atlantic seashore. Here, at the latitude of Virginia, the transect crosses what once was an immense forest of oak and hickory (Fig. 1.1). According to folklore, an ambitious squirrel could have journeyed from the Atlantic seaboard to the Mississippi River 300 years ago without the necessity of ground travel, false testimony to the idyllic notion that an unbroken canopy of deciduous forest once stretched across more than a third of North America.

Figure 1.1 A vast expanse of eastern deciduous forest once covered much of North America east of the Mississippi River, but the romantic notion of an unbroken canopy 300 years ago is inaccurate. Indeed, Native Americans and natural processes, such as fire, periodically cleared many areas, some quite large, within the primordial forest. A mountaintop bald, visible atop the Smoky Mountain ridge (right), represents a natural opening described in more detail in Chapter 3. Photo courtesy of Brian R. Chapman.

Westward, with the Appalachians, Cumberland Plateau, and Mississippi River behind us, the forest gradually thins and our transect enters the grasslands. Our trek skirts the southern edge of the Prairie Pothole Region – North America’s famed “duck factories” – and pushes onward toward the plains. As we cross our north–south transect in western Kansas, courting prairie chickens dance and boom in the background and black-tailed jackrabbits crouch, ears lowered, to escape our notice. Still farther west rise the Rocky Mountains with their rather distinctive zones of vegetation, after which we enter into a desolate terrain of sagebrush in the Great Basin. In the distance loom the peaks of the Sierra Nevada where the largest of trees, the giant sequoia, almost defy description. In a quiet grove of these immense trees, we might allow our imagination to behold the ghost of John Muir (1838–1914), the hard-trekking Scot who championed wilderness preservation.

By the time we reach the rocky seashore of the Pacific Ocean, our transect will have dropped into the Central Valley of California and then risen upward to cross the Coastal Range that rims the western edge of the continent. Offshore, frisky sea otters float above submerged kelp forests. North of where we stand are the old-growth forests of Sitka spruce and western hemlock, heavily draped with epiphytes, replete with spotted owls and maples. On the Alaskan coast, vulnerable hoards of migrating salmon attract giant bears to the rushing streams each year. To the south are chaparral-covered hills, and beyond these are the beckoning Joshua trees in the Mojave Desert. Still farther south at a small site in the mountains of Mexico are firs cloaked each winter with millions of slumbering butterflies. Our telescoped journey across North America has been brief to be sure, but perhaps it is long enough to preview the contents of this book.

A brief overview of ecology

Ecology is the branch of biology that investigates the interrelationships between organisms and their environment. The original name oekologie, based on the Greek word oikos meaning “home”, was coined in 1866 by German zoologist Ernst Haeckel (1834–1919). An ecological study of any species involves a detailed examination of an organism’s life history and biological requirements, the physical environment in which the organism lives, and its interactions with the other species that occupy the same area. Physical features of the environment (e.g., temperature, soil type, and moisture) influence the distribution and abundance of organisms, but all living things process materials from the environment and transform energy as they grow and reproduce.

The ecosystem

In 1935, English botanist Arthur G. Tansley (1871–1955) proposed the term ecosystem to characterize the flow of energy and matter through a network of food chains collectively known as a food web. Energy passes through a series of trophic levels (i.e., feeding levels), the functional parts of an ecosystem. These rest on a foundation of non-living matter, the abiotic level, which consists of air, soil, and water. When fueled by sunlight, the abiotic level provides the fundamental components required for photosynthesis by species known as primary producers, which are represented by green plants such as algae, grasses, and trees and first in the series of trophic levels. Primary consumers – rabbits, deer, or other herbivores that consume the energy and matter bound in green plants – represent the next trophic level, followed by secondary consumers; the latter are predators such as foxes or hawks. Tertiary consumers, sometimes known as apex predators, are represented by animals such as polar bears or mountain lions. The final trophic level, decomposers, is populated by scavengers, bacteria, and fungi that return the tissues of dead plants and animals to their elemental form (Fig. 1.2). An ecosystem is therefore an area or volume in which energy and matter are exchanged between its living and non-living parts.

Figure 1.2 In forests decomposition is commonly thought to originate with logs, but it often begins when a dead tree remains upright as a snag. The bracket fungi on this snag possess enzymes that break down lignin and other complex chemicals found in wood, and the fungi absorb the nutrients for their growth and reproduction. When the snag eventually falls, other decomposers on the forest floor will return its elements to the soil. Photo courtesy of Brian R. Chapman.

Abiotic limits

Many environmental influences – such as moisture, temperature, the availability of nutrients, wind, and fire – limit the kinds and abundances of organisms that populate an ecosystem. In 1840, German organic chemist Justus von Liebig (1803–1873) was the first to recognize the role of abiotic limitations in nature. After studying the relationships between surface soils and agricultural plants, Leibig concluded: “The crops of a field diminish or increase in exact proportion to the diminution or increase of the mineral substances conveyed to it in nature.” Liebig recognized that each plant requires not only certain minerals, but each must also be present in the proper quantity for the plant to flourish. If a required nutrient is absent, the plant will not survive. Moreover, if the essential food substance is present only in a minimal amount, the plant’s growth will be correspondingly minimal. In later years, this concept became known as the law of the minimum.

Later studies indicated that the growth and survival of living organisms also may be limited by an overabundance of a required substance (e.g., terrestrial plants require moisture, but die when waterlogged for a prolonged period). Plants and animals are successful only when they live in an environmental range between too much and too little, that is, within their limits of tolerance. Victor E. Shelford (1877–1968; Infobox 1.1) incorporated the concept of maximum and minimum limits on environmental condition into the law of tolerance in 1913. Some organisms are capable of living within wide ranges of conditions of one or more environmental factors, whereas others have narrow limits of tolerance. Certain species are capable of acclimatizing to different environmental limits as seasons or conditions change.

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Infobox 1.1 Victor E. Shelford (1877–1968), Father of animal ecology

The scientific career of Victor Shelford began in 1899 when he enrolled at West Virginia University where his uncle, the assistant state entomologist, influenced his lifelong interest in insects. In 1901, however, the president of the university moved to the University of Chicago where he offered a scholarshi...

Table of contents

• Cover
• Title page
• Table of Contents
• Foreword
• Preface
• Acknowledgments
• CHAPTER 1: Introduction
• CHAPTER 2: Tundra
• CHAPTER 3: Boreal Forest
• CHAPTER 4: Eastern Deciduous Forest
• CHAPTER 5: Grasslands
• CHAPTER 6: Regional Grasslands and Related Areas
• CHAPTER 7: Deserts
• CHAPTER 8: Chaparral and Pinyon-Juniper Woodlands
• CHAPTER 9: Montane Forests
• CHAPTER 10: Temperate Rain Forest
• CHAPTER 11: Coastal Environments
• CHAPTER 12: A Selection of Special Environments
• Appendix
• Glossary
• Index
• End User License Agreement