The Work of Nature: How The Diversity Of Life Sustains Us / Edition 3

by Yvonne Baskin, Harold A. Mooney, Jane Lubchenco, Abigail Rorer, Paul R. Ehrlich

Overview

The lavish array of organisms known as "biodiversity" is an intricately linked web that makes the earth a uniquely habitable planet. Yet pressures from human activities are destroying biodiversity at an unprecedented rate. How many species can be lost before the ecological systems that nurture life begin to break down?

In The Work of Nature, noted science writer Yvonne Baskin examines the threats posed to humans by the loss of biodiversity. She summarizes and explains key findings from the ecological sciences, highlighting examples from around the world where shifts in species have affected the provision of clean air, pure water, fertile soils, lush landscapes, and stable natural communities.

As Baskin makes clear, biodiversity is much more than number of species — it includes the complexity, richness, and abundance of nature at all levels, from the genes carried by local populations to the layout of communities and ecosystems across the landscape. Ecologists are increasingly aware that mankind's wanton destruction of living organisms — the planet's work force — threatens to erode our basic life support services. With uncommon grace and eloquence, Baskin demonstrates how and why that is so.

Distilling and bringing to life the work of the world's leading ecologists, The Work of Nature is the first book of its kind to clearly explain the practical consequences of declining biodiversity on ecosystem health and function.

Product Details

ISBN-13:	9781559635202
Publisher:	Island Press
Publication date:	08/01/1998
Edition description:	None
Pages:	282
Product dimensions:	6.00(w) x 9.00(h) x 0.70(d)

About the Author

Yvonne Baskin is author of The Work of Nature (Island Press, 1997) and A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions (Island Press, 2002). Her articles have appeared in Science, Natural History, Discover, and numerous other publications.




Paul R. Ehrlich is a co-founder with Peter H. Raven of the field of co-evolution, and has pursued long-term studies of the structure, dynamics, and genetics of natural butterfly populations. He has also been a pioneer in alerting the public to the problems of overpopulation, and in raising issues of population, resources, and the environment as matters of public policy. Ehrlich is the author of The Population Bomb, and many other books, as well as hundreds of papers.

Ehrlich is a fellow of the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the American Philosophical Society, and a member of the National Academy of Sciences. Ehrlich has received several honorary degrees, the John Muir Award of the Sierra Club, the Gold Medal Award of the World Wildlife Fund International, a MacArthur Prize Fellowship, the Crafoord Prize of the Royal Swedish Academy of Sciences (given in lieu of a Nobel Prize in areas where the Nobel is not given), in 1993 the Volvo Environmental Prize, in 1994 the United Nations' Sasakawa Environment Prize, in 1995 the Heinz Award for the Environment, in 1998 the Tyler Prize for Environmental Achievement and the Dr. A. H. Heineken Prize for Environmental Sciences, in 1999 the Blue Planet Prize, in 2001 the Eminent Ecologist Award of the Ecological Society of America and the Distinguished Scientist Award of the American Institute of Biological Sciences.

In addition to The Population Bomb, Ehrlich is the author of Human Natures: Genes, Cultures, and the Human Prospect (Island Press, 2000) and co-author of The Work of Nature: How The Diversity Of Life Sustains Us (Island Press, 1998).

With his wife Anne, he is the author of Betrayal of Science and Reason: How Anti-Environmental Rhetoric Threatens Our Future (Island Press, 1996) and One With Nineveh: Politics, Consumption, and the Human Future (Island Press, 2004).

His latest book with Anne is The Dominant Animal: Human Evolution and the Environment (Island Press, 2008).

Paul R. Ehrlich received his Ph.D. from the University of Kansas.

Read an Excerpt

The Work of Nature

How the Diversity of Life Sustains Us

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By Yvonne Baskin

ISLAND PRESS

Copyright © 1997 The Scientific Committee on Problems of the Environment (SCOPE)
All rights reserved.
ISBN: 978-1-55963-520-2

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CHAPTER 1

This Web of Life

Overleaf

Ecologists are starting to probe how plants and animals help to generate vital ecological services such as productivity and nutrient cycling.

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Our oldest faiths and deepest symbols reflect a primal connection to the natural world, to a living planet that long ago imprinted on the human consciousness a cyclic sense of death and decay, rebirth and renewal. We do not question that flesh and bone and leaf litter will decay to dust, that seeds will sprout season after season and find renewed nourishment in the soil, that rivers can flow endlessly without running dry, that we can breathe for a lifetime without depleting the air of oxygen. Despite our fascination with other worlds and our hopeful probing of outer space, we've found no other planet where any of these things are true. What humans have not fully appreciated until recently is that these services are the work of nature, performed by the rich diversity of microbes, plants, and animals on the earth.

It is this lavish array of organisms that we call "biodiversity," an intricately linked web of living things whose activities work in concert to make the earth a uniquely habitable planet. But today, as never before, the species in this web are under siege, threatened by human activities that encroach on their habitats. At the same time, ecologists are increasingly aware that the impoverishment of species—the planet's work force—threatens to erode the basic life-support services that render the earth hospitable for humanity. Indeed, we are approaching a crossroads in time, when the survival and extinction of other species may well delimit the future of Homo sapiens.

Consider what life has done and continues to do for the earth.

Some 4 billion years ago, the primordial atmosphere was a ghastly brew, devoid of oxygen and unable to shield the earth's surface from the scorching, molecule-cleaving ultraviolet radiation of the young sun. Eventually life changed all that. Over billions of years, photosynthetic organisms in the sea released enough oxygen to create a protective ozone shield and a reservoir of free oxygen that allowed the first plants to venture onto the land. Through the alchemy of enzymes and solar energy, green plants from plankton to redwoods still carry on photosynthesis, turning water and carbon dioxide into free oxygen and also the carbon-based sugars needed to build all living tissues. These are the raw materials that underpin the earth's food webs and generate the food, fiber, timber, and fuel that sustain human societies.

Together, plants, animals, and microbes perform an array of vital services. They generate and preserve fertile soils. They break down organic wastes, from leaf litter to feces and flesh, recycling the mineral nutrients, carbon, and nitrogen needed for new plant growth. They absorb and break down pollutants; help maintain a benign mix of gases in the atmosphere; regulate the amount of solar energy the earth absorbs; moderate regional weather and rainfall; modulate the water cycle, minimizing floods and drought and purifying waters; blunt the impact of the seas that batter the land margins; pollinate crops; and control the vast majority of potential crop pests and carriers of human disease.

In addition, this rich abundance of organisms serves as a "genetic library," a catalog of solutions to the problems of living on the earth. This catalog is written in the language of DNA, and from it human societies have derived crops, livestock, medicines, and many other commodities.

On a larger scale, the earth's various species form populations that are aligned into communities and ecological systems—ecosystems, for short—which deliver such subsidies as clean air, pure water, and lush landscapes. Ecosystems, flexibly defined, are living communities interacting with the physical environment in a specific geographical place. An ecosystem may be as small as a rotting log or a pond or as large as a spruce forest or a vast lake. Of course, species are the critical components, the cogs and wheels of functioning ecosystems. Lose too many species from a forest—the trees, the truffle-forming fungi on their roots, the insects that prey on tree-destroying pests, the beavers that create ponds and meadows amid the woods—and at some point the assemblage ceases to work like a forest.

One question increasingly on the minds of ecologists is, how many species can the earth's communities lose before the ecological systems that nurture life begin to falter? To take the extreme, if nature had to run with a skeleton crew, what organisms would be absolutely vital to maintain the earth as a living planet? Probably the only truly indispensable groups of organisms are the plants that capture carbon and solar energy and the ranks of decomposers that release the nutrients and energy in dead plant litter for reuse. But a conservation agenda based on this extreme would ignore the elaborate tangle of loops and flourishes in the food webs, the intricate array of consumers that eat plants and predators that eat consumers, the symbionts, parasites, and other hangers-on who have claimed places for themselves in the earth's myriad communities. Such an agenda would overlook virtually all the charismatic creatures on today's conservation hot lists: pandas, wolves, elephants, bald eagles. Unfortunately, that agenda would also sacrifice civilization, which is supported by many of those loops and flourishes in the web of life.

If we are realistic about our dreams for tomorrow, our goal is not really "saving the planet" in some minimalist form, but perpetuating its atmosphere, climate, landscapes, and living services in a state that allows human civilizations to prosper. For that to occur, we need to preserve natural systems that are rich, healthy, and resilient enough to continue to support human welfare and economic activity for the next decade, the next century, and beyond. Some twenty-five years ago, as the space-age metaphor of "Spaceship Earth" took hold, ecologists Eugene P. Odum of the University of Georgia and his brother, Howard T. Odum, of the University of Florida first used the engineering term "life-support systems" to describe the earth's self-renewing, life-giving natural ecosystems. It is these systems, not a mere skeleton crew, that human societies must seek to maintain.

Thus, the real questions facing ecologists today center on how much biological diversity any particular ecosystem needs to remain functional, self-sustaining, and life supporting. How many species must humanity protect, and which ones and where, to assure pure water supplies from an alpine watershed; to preserve the fertility of tropical soils; to prevent cactus and shrubs from taking over productive grasslands; to maintain local rainfall patterns; to nurture coastal shrimp and fish populations; or to assure the integrity of pristine wildlands we value for recreation, tourism, or cultural traditions?

Conservationists have long asserted that every species counts to some degree in keeping the earth's life-support systems working. Some play crucial roles day to day; others step into the breach only in times of stress or disturbance. Until recently, however, researchers have made little concerted effort to define the functional roles played by specific plants, animals, or microbes. In truth, function itself is a human concept. Organisms were not designed by natural selection to fill slots on an assembly line; each organism strives to make a living and reproduce itself. But as it eats, grows, excretes waste, and moves about, disturbing the physical environment, it unwittingly plays a part in generating grander processes that alter the flow of water, the recycling of energy and materials, the renewal of the atmosphere.

An Emerging Science

It may seem surprising that scientists know so little about species' roles in generating ecological services. Yet unraveling links between the feeding behavior of an animal or the nutrient-cycling traits of a plant and subsequent changes in the character of a landscape or the chemistry of the soil may require years of observations, experiments, and analysis. Sometimes this work spans professional lifetimes and thus extends well beyond the practical scope of graduate student projects and the longevity of most research grants.

The questions also cross the lines of professional disciplines. Until recently, there were specialists who studied ecosystems and others who studied species and populations, and there was minimal discourse between them. Ecologists concerned with ecosystem processes such as nutrient cycles and energy flows, for instance, have traditionally focused on quantifying the work that gets done in a given system, not who does it. These ecologists might chart the flow of energy through a food web, filling in numbers atop arrows that run from plant producers to herbivore consumers, predators, and, finally, decomposers. Few have attempted to fill in the names and numbers of the organisms doing the work at each level, much less to determine how many of the species could be lost before the cycles faltered and the arrows had to be erased.

Population biologists, for their part, ask what determines the abundance of plants and animals, why certain creatures live where they do, how they interact with their neighbors, and why one species is part of the community while another is not. They also look at food webs and study herbivory and predation, but traditionally they have not translated into quantified flows of carbon the dynamics, say, of moose browsing on birches or wolves feasting on elk.

Scientists now recognize, however, that the two research traditions must come together if they are to understand how biological losses impair ecological services. As part of a broader movement to integrate these traditions, the Scientific Committee on Problems of the Environment (SCOPE) launched a project in 1991 that would lay the foundation for an emerging scientific discipline linking ecosystem processes with biological diversity.

SCOPE is a committee of the International Council of Scientific Unions (ICSU), a nongovernmental body established in 1931 to promote international science and its application for the benefit of humanity. SCOPE was created by ICSU in 1969 to identify gaps in environmental knowledge, assess research needs, and provide syntheses of existing scientific information on emerging environmental issues. Its projects are funded by a wide variety of sources, from United Nations agencies, the World Bank, and the European Communities to various governmental agencies and private foundations. The projects are carried out by scientists who donate their time and expertise.

During the three-year SCOPE program on ecosystem functioning, hundreds of scientists from around the world came together at a series of meetings and workshops to synthesize what is known so far about the functional role of biodiversity at all levels. Biodiversity is most often talked about in terms of numbers of species, yet the SCOPE teams expanded that perspective to include the complexity, richness, and abundance of nature at all levels, from the genes carried by each local population of a species to the layout of communities and ecosystems across the landscape.

Although much of the information came from the literature of ecology, the SCOPE team also took a much broader view, drawing on relevant studies from a wide array of other sciences: forestry, soil science, agriculture, plant pathology, range management, fisheries, microbiology, limnology, oceanography, marine biology, hydrology, meteorology, and atmospheric sciences. Results of the team's synthesis have been published in a number of technical volumes, many of them dealing with specific biotic regions of the world such as savannas, tropical forests, islands, and arctic and alpine ecosystems.

The Work of Nature relies heavily on the ideas and examples assembled during the SCOPE project. It is intended to introduce students, policymakers, and concerned citizens to the risks our own species incurs when we impoverish the rest of the life of the planet. This book is not meant to be an exhaustive account of species' roles in providing life-support services but rather a suggestive and cautionary tale from the frontiers of a new science. The SCOPE assessment showed that most of the information scientists have accumulated so far about ecosystem functioning and biodiversity deals with species rather than diversity at other levels, from genes to landscapes, and so this book focuses predominantly on the work of species.

The SCOPE assessment makes it clear that species are not ecologically equal; some are more valuable in terms of service rendered than others. Yet so little is known about the prodigious array of organisms on the earth, and so few names have been entered into the flow charts of energy and materials, that it would be both premature and irresponsible to declare any species, however humble, expendable.

How should scientists begin, then, to identify those species and natural communities whose loss will cause the greatest impacts on ecological processes? One approach the SCOPE teams took was to look for clues indicating which species play indispensable roles—either as dominant species or as so-called keystones, which are less imposing creatures from a human point of view, but ones that hold the key to the integrity of their communities. The Work of Nature explores the progress ecologists have made so far in learning how to spot such creatures, and also in determining whether most communities have alternates—backup workers—that can step in and compensate for the loss of a dominant or keystone species.

Another approach taken by the SCOPE researchers was to examine ecosystems directly to determine how the traits or activities of individual species might influence ecological processes. The Work of Nature highlights examples where shifts in species have affected

• the persistence and stability of natural communities;

• water quality and flow and the health of aquatic habitats;

• soil fertility and its relation to healthy crops and forests;

• the productivity or lushness of both our wild lands and agricultural lands;

• the look and functioning of the landscape and the frequency of disturbances, such as fires; and

• local rainfall patterns and weather, as well as the state of the atmosphere and global climate.

The Biodiversity Crisis

The Work of Nature, like the emerging science it portrays, comes at a critical time. We are in the midst of a biodiversity crisis, an ongoing epidemic of species losses that British conservation scientist Norman Myers has labeled "biodepletion." The richness and complexity of the natural world is declining at an ever-accelerating rate, as the earth's burgeoning human population strives for a steadily rising technological standard of living. Natural diversity is being brutally simplified to make way for a dizzying blend of artificial landscapes—villages, housing developments, parking lots, roads, factories, mines, shopping malls, schools, parks, gardens, golf courses, plantations, and croplands.

The biggest threats to the diversity of life on the earth are habitat loss, introduction of alien species into communities, and fragmentation of natural areas caused by bulldozing, paving, plowing, draining, dredging, trawling, dynamiting, and damming. Humans are also plundering natural communities by overharvesting, overgrazing, dousing them with excessive pesticides and herbicides, raining acids and other pollutants onto them, altering the mix of gases in the air, and even thinning the ultraviolet radiation shield on which terrestrial life depends.

Many of these assaults are so massive they wipe out entire ecosystems and disrupt natural processes immediately and directly. For example, draining and filling wetlands or permanently stripping the forest from a watershed instantly eliminates the flood and erosion control, water filtration and purification, and other services those ecosystems provide. Dynamiting a coral reef to extract fish not only destroys the ecosystem, but also exposes the now-unprotected shoreline to storms and so threatens coastal habitats. The impacts of such obvious forms of destruction are immediate and direct. Of equal concern to many scientists, however, is the slower, usually more insidious chipping away of functioning that accompanies the loss of species and impoverishment of their habitats. This erosion of service is harder to spot until it's well underway—easier for developers and government officials and the public to ignore for the moment. After all, what's so serious about losing a few more hectares of land to a few more houses?

Yet even simple questions, such as, "how quickly is this subtle impoverishment proceeding?," have no easy answers. Furthermore, the answer is endlessly contentious, partly because scientists have no clear tally, even to the nearest tens of millions, how many species share the earth with us. For instance, about 1.4 million species of plants, animals, and microbes have been formally identified and given Latinized names. But that itself is an estimate because no computerized database of the life of the planet has ever been compiled—a stunning omission given the great care and expense with which every newly discovered bit of the human genetic code is digitized and celebrated into cyberspace.

These named species are but a fraction of the actual diversity of life on the planet. Scientists know that because every time a trained researcher explores some poorly studied bit of habitat—the floor of the deep sea, the canopy of a tropical rain forest, a scoop of ordinary soil—he or she comes upon a wealth of previously unknown species. In one classic case, Terry L. Erwin of the Smithsonian Institution in Washington, D.C., misted the canopy of rain forest trees in Panama and elsewhere with an insecticidal fog and found that up to twelve hundred beetle species, many new to science, tumbled into his nets from a single species of tree. Many of the beetles were specific to a single tree species, existing nowhere else. Extrapolating from these counts, using the estimated number of tree species in the tropical forests, Erwin calculated that there may be 30 million species of insects and other arthropods in the tropical forests of the world.

(Continues...)

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Excerpted from The Work of Nature by Yvonne Baskin. Copyright © 1997 The Scientific Committee on Problems of the Environment (SCOPE). Excerpted by permission of ISLAND PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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Table of Contents

Foreword: Of Keystone Complexes and Nature's Services
Preface
Acknowledgements
 
Chapter 1. This Web of Life
Chapter 2. The ''Keystone Club: Who's Important
Chapter 3. Community Ties
Chapter 4. Water: The Essence of Life
Chapter 5. The Vitality of the Soil
Chapter 6. Of Plants and Productivity
Chapter 7. The Power to Shape the Land
Chapter 8. Climate and Atmosphere
Chapter 9. Do We Still Need Nature?
 
Notes
Index

Editorial Reviews

"[a] 'must read' for teachers, students, scientists, and citizens at all levels of expertise. The valuation of nature should be considered and widely debated by all concerned with humanity's future."

Nature

"[a] 'must read' for teachers, students, scientists, and citizens at all levels of expertise. The valuation of nature should be considered and widely debated by all concerned with humanity's future."

Nature Lib