The terms “ecosystem” and “Dust Bowl” coincidentally both entered the English language in 1935. Before then ecologists had focused on the study of plant and animal “communities,” but British ecologist Arthur Tansley thought they were neglecting the surrounding earth, air, and water. He suggested that the word “ecosystem” better captured the connections between the living and nonliving worlds.1 He did not have the Dust Bowl in mind when he did so, but the Dust Bowl, as the worst environmental disaster that modern Americans had ever experienced, is a stunning example of a collapse of natural infrastructure resulting in a loss of ecosystem services. Henry A. Wallace, secretary of agriculture at the time, warned that Americans had a duty to protect the soil to create a foundation for the nation’s future.2 The bad habits of overplowing, overgrazing, and overcutting of timber that brought on the Dust Bowl might be excusable in a young civilization, he declared, but not in the United States in 1938. Two generations later we express similar views of our debt to nature and duty to future generations when we assert the importance of protecting ecosystems so as to maintain “ecosystem services,” or in other words, to maintain our life-support systems.
What is an ecological “system” and how has ecosystem ecology shaped our understanding of these beneficial “services”? Tansley’s “ecosystem” term did not catch on right away, but it took on new meaning after the Second World War as ecologists grappled with new kinds of problems. By the 1960s the ecosystem concept had become a central ecological idea.3,4 It dovetailed with the rise of systems thinking in other fields, for instance in cybernetics, a new science that studied feedback and control in any kind of system. A typical problem in cybernetics was how to guide missiles toward their targets. The cybernetic approach could also be applied to the behavior of organisms to explain how goal-directed behaviors are the result of physiological feedback mechanisms. By extension this approach could apply to larger groups of organisms that are linked ecologically through the food web, forming ecosystems.
When ecosystem ecology first emerged in the 1950s, many were doubtful of the value of this neologism. The two people most responsible for arguing that the ecosystem was a system in this cybernetic sense were Eugene P. Odum and Howard T. Odum, brothers who became leading ecosystem ecologists. They collaborated on one of the most successful ecology textbooks of all time, Fundamentals of Ecology, first published in 1953, which made the ecosystem concept the central organizing principle of ecology and emphasized the many applications of ecology to current problems.5 Over the next two decades the concept assumed greater meaning as ecologists studied the “web of life” and filled in details about how systems worked.
The ecosystem perspective in ecology studied how materials, such as nitrogen, phosphorus, or carbon, moved back and forth between living and nonliving parts of the system, forming a cycle driven by energy from the sun, which was captured by photosynthesis. The value of the ecosystem concept as an organizing principle came from the way it focused attention on how multiple feedbacks between organisms and their environment resulted in stable natural systems. That is, ecosystems were stable because they were ecologically complex. When humans removed species and simplified ecosystems, they also made them less stable. The ecosystem perspective, in Howard Odum’s view, provided a way of seeing the big picture: it was a macroscopic view of the world meant to identify the system’s main features and to help figure out what preserved or destroyed its stability. The flip side of this focus on stability was the idea that ecosystems might collapse quite suddenly if they became unstable. The environmental debate that unfolded in the 1960s and 1970s placed great emphasis on preventing catastrophic collapse.
Ecosystem ecology was a science of the atomic age. With the development of atomic energy and the atomic bomb, radiation sources were becoming more numerous, and knowledge of the pathways of radiation and accumulation points for radiation in ecosystems was needed. Since we would be living in a world with increased radiation sources, it was important to understand how radioactive materials entered our diet through the food chain and whether they posed a health risk. As the national laboratories became centers for the development of atomic technology in the postwar period, they also became growth centers for ecosystem ecology. Much of the funding for ecological research came from the Atomic Energy Commission, and with this help Eugene Odum built a major center of ecology at the University of Georgia. The Odum brothers also studied coral reef ecosystems at bomb-testing sites in the Marshall Islands. By the 1970s ecologists were developing a much more sophisticated understanding of the many ways that ecosystems served as life-support systems for the inhabitants of “spaceship earth.”
These life-support systems endured for relatively long periods. Even with disturbances like fire, a healthy system could adjust and reestablish itself. If it could not adjust to normal disturbances, it was unhealthy. Usually humans were the cause of serious maladjustments and therefore humans came to be seen as pathogens or cancers, causing illness to the system or malfunction in nature’s machinery. The debates about overpopulation that came to dominate environmental discussions in the late 1960s and early 1970s, as exemplified by Paul Ehrlich’s polemic of 1968, The Population Bomb, also played up this image of human population growth as a cancer on the earth.
But exhorting people to stop reproducing for the sake of the planet’s health was not an effective solution. Calculating and explaining the value of natural systems to people seemed a better way to connect conservation to human self-interest. The concept of “nature’s services” or “ecosystem services” started to be more carefully articulated in the 1970s, and here too the Odum brothers led the way. As they explained, people commonly valued developed areas like cities and wanted to preserve them, but “cities need the protection of an adequate life support system, many elements of which [the] natural environment provides free of charge.”6 Without natural “free” services, such as purifying water by filtering it through the ground, the expense of maintaining a desirable quality of life in a city would be prohibitive, and cities would go bankrupt if forced to pay the costs. In this way the Odums emphasized the need to see natural and built environments as connected. If the quality of the natural environment was degraded, the quality of the developed environment would also deteriorate. The feedbacks connecting the natural and social systems also had to be understood. The Odums realized that a vast amount of research was needed to get a more accurate reading of how the systems were functioning. However, they thought it was worth trying out these new concepts in urban planning, especially in places where public opinion and government already supported the goal of controlling development.
Wetlands were one type of landscape whose vital services were often unrecognized. In a study published in 1974, James Gosselink, Eugene Odum, and R. M. Pope drew attention to the need to protect tidal marshes that were “vulnerable to capricious development because many of the real values of the marshes are not recognized, or accrue some distance from the marsh itself.”7 For lands in private ownership, they recommended devising a system that allowed owners of natural resources that were of value to society to receive a return in exchange for protecting lands from development. They also recommended a long-term strategy whereby lands that performed key life-support functions could be acquired and protected before land speculation drove up the market price. The devastating impact of Hurricane Katrina on New Orleans and its barrier islands in 2005, worsened by degradation of the coastal ecosystem due to overdevelopment on the Mississippi River, demonstrated the wisdom of thinking ahead and not waiting for disaster to strike.
Where the ecosystem services argument focused on the need to preserve natural ecosystems, an alternative argument placed greater value on technology, management, and human ingenuity. The notion that we could engineer our way toward complete control of nature, or toward solutions to environmental problems, was common in postwar reflections on the future and had various expressions. One militant form of this argument held that we were engaged in a war against nature and needed to eradicate pests in order to win the war.8 Rachel Carson famously argued against this logic in 1962 in her exposé of pesticide overuse, Silent Spring. Her point was that we needed to control ourselves, not nature.
Another argument drew from agricultural experience, extolling our ability to restore degraded lands and even to manage wilderness. Walter Lowdermilk from the U.S. Department of Agriculture found Israel’s reclamation of damaged lands to be inspirational as a model for the development of arid and semiarid regions elsewhere.9 R. Merton Love, agronomist and range scientist at the University of California, Davis, argued in 1970 that in time we would be able to manage wilderness much as we had learned to manage our agricultural systems.10 His vision was of total human control over ecosystems, and he argued that the prevailing conservation ethos should be replaced with an active management ethos. Ecologists John P. Holdren, Richard W. Holm, and Paul Ehrlich countered that the faith in technology or management that Lowdermilk and Love evinced was unrealistically optimistic at best and dangerously misconceived at worst.11 Israel was a special case and could not be a model for poorer nations, and Love’s approach rashly ignored the possibility that “wilderness contains answers we have not yet learned to seek.”11
Holdren and Ehrlich also worried that environmental debates in the 1970s were placing too much emphasis on solving acute problems, such as pollution, while neglecting other problems, in particular the loss of the “public service” functions of ecosystems.12 In 1974 they argued that human impact on the earth’s systems showed that humans were a global ecological force, and unless population and consumption slowed down we were heading for disaster. At the same time, studies of pollution damage also steered attention to the larger question of how ecosystems provided critical services, such as clean air and water, binding of soil, or regulation of climate. Walter E. Westman, ecologist at the University of California, Los Angeles, and economist W. David Conn made a study of the damage from air and water pollution caused by energy production in California. Their report took a broad look at how we are deprived of important ecosystem services when we interfere with ecosystem functions, while acknowledging that the scientific study of these services was in its infancy. In 1977 Westman summarized their findings in a cogent appeal to recognize the value of ecosystem services.13 One of his conclusions bears repeating today: that the public needed to have “a clear idea of the benefits they obtain from nature in its undeveloped state” so that they could convey to their government representatives their desire to preserve nature and control development.
Despite the discussions of the 1970s, ecosystem services did not emerge as a central theme of environmentalism until the late 1990s, aided by such books as Nature’s Services: Societal Dependence on Natural Ecosystems, edited by Gretchen Daily and published in 1997. A group of prominent ecologists and economists, led by Robert Costanza, one of Howard Odum’s former PhD students, joined forces to estimate the value of 17 ecosystem services worldwide and came up with a conservative estimate that their value was at least equal to the global gross national product.14,15 Daily and Katherine Ellison followed up with an international survey of recent efforts to determine the value of natural assets.16 These efforts were meant to jolt policymakers and the public into awareness of the huge cost of ecological damage.
Daily explained that the idea for the first book emerged when a group of environmentalists started lamenting “the near total lack of public appreciation of societal dependence upon natural ecosystems.”17 Harold Mooney and Paul Ehrlich argued that, although there were a few precedents for the notion of ecosystem services (as far back as Plato), the public remained “sadly unaware” of the connection between human welfare and ecosystem services.18 They blamed the education system, public media, and also professional ecologists who collectively had failed to get the message out. Environmentalists also deplored the way the environmental debate had unfolded over the past half century. The regrettable habit of pitting technological optimists against environmental pessimists, as if these were two diametrically opposed worldviews, was stalling progress. It was time to start presenting complex issues in a balanced way.19
Presenting things in a balanced way also means that democratic societies must make choices about when to preserve, when to manage, and what kinds of technological solutions might work. The issues are indeed complex and we return to the problem of educating the public about what it means to maintain ecosystem services. We cannot rely on catastrophes like the Dust Bowl or Hurricane Katrina to deliver a sharp reminder to mend our ways. This raises the question of where and how ecological education should be conducted.
The essays in Daily’s volume focused on natural ecosystems, an understandable choice given the authors’ fears that these might soon disappear. But while it is important to know that such natural systems provide crucial services and must be protected, most people live in urban environments. If public opinion is to be changed, the place to do it is in the city, where people can see and experience both loss and improvement of ecosystem services.
Changes do not have to occur on an ecosystem-sized scale to impart lessons. People who decide to plant trees or turn a vacant lot into a garden are experiencing restoration of ecosystem services, and if it’s a poor neighborhood they will see their home values increase as a result of such greening efforts. In an area of Baltimore known as Reservoir Hill, a dedicated community has been working for six or seven years to improve a depressing environment of vacant row houses one block at a time.20 Along the way, environmental education has been introduced in the local elementary school and recreation center, and the community has built partnerships with local businesses and religious institutions. Baltimore’s Parks and People Foundation, which works to create connections between the city’s network of parks, also provides greening advice to communities and fosters communication among groups. Such community-based activities help people to understand what it means to think of the urban environment as an ecosystem.
Community-based activism can profoundly influence a society’s approach to its environment. In Toronto, Canada, a group called Friends of the Spit has been working for years to protect an urban wilderness that arose quite by accident and then grew into a cause célèbre in the city. The “spit” in question is the Leslie Street Spit, a narrow peninsula jutting five kilometers into Lake Ontario in Toronto’s east end.21 This artificial peninsula has been built up since the 1950s from harbor dredging and construction landfill. As vegetation grew on the site, it attracted birds and other animals; over time people began to see the spit as an emerging wilderness area. In 1977 Friends of the Spit was founded to lobby for public access to the site and for its protection, even as it was still being used as a construction landfill. For years the group battled various development plans for the waterfront area, always maintaining that the best plan was to leave the spit alone. Their dedication paid off and today the park is lauded as a unique urban wilderness. With more than 300 species of birds it has been named an Important Bird Area by a global alliance called BirdLife International that seeks to conserve bird diversity worldwide.
One consequence of this decades-long effort was to challenge the prevailing view that a park should have a finished or unchanging look. The spit, as a work in progress, is instead a classroom for the study of ecological succession. As it evolves it teaches about changing ecological relationships, enabling visitors to experience biological diversity in a way that is impossible in a more managed park.
These urban dwellers in Baltimore and Toronto may not be sitting down with calculators to figure out the hidden value of a tree, bird, or butterfly, and they are not operating on the level of an entire ecosystem. But they are all getting a direct lesson that ecosystem services improve their lives. Exercises in civic activism also educate people about how to be effective advocates for better practices. Such activism and its results may seem too small to matter, but a recent analysis of how we should approach ecosystem services poses the question, “Can ecosystem services be maintained solely through global or large-scale environmental policies without regard to regional or local-scale policy making?”22 Policymaking on the local scale implies a need for education that uses examples on the local scale as well.
Even small-scale experiments are opportunities to raise people’s awareness of how improved ecosystem services can affect their health, well-being, and wealth, but the lessons need to be extracted. We need a recorder and observer along the lines of Jane Jacobs, author of the 1961 classic The Death and Life of Great American Cities, which opened many people’s eyes to what makes cities great.23 She walked around cities, analyzing what created a vibrant, healthy cityscape and what did not. There would be high educational value in observing the urban scene as Jacobs did, but with an emphasis on ecosystem services, showing how the transformations (good or bad) that are continually occurring in cities can be translated into ecological terms and related to people’s well-being.
- Tansley, AG. The use and abuse of vegetational concepts and terms. Ecology 16, 284–307 (1935).
- Wallace, HA. Foreword to Soils and Men: Yearbook of Agriculture 1938 (U.S. Government Printing Office, Washington DC, 1938).
- Hagen, JB. An Entangled Bank: The Origins of Ecosystem Ecology (Rutgers University Press, New Brunswick, NJ, 1992).
- Kingsland, SE. The Evolution of American Ecology, 1890–2000 (Johns Hopkins University Press, Baltimore, 2005).
- Hagen, JB. Teaching ecology during the environmental age, 1965–1980. Environmental History 13, 704–723 (2008).
- Odum, EP & Odum, HT. Natural areas as necessary components of man’s total environment. Transactions of the North American Wildlife and Natural Resources Conference 37, 178–189 (1972).
- Gosselink, JP, Odum, EP & Pope, RM. The Value of the Tidal Marsh, 1 (Center for Wetland Resources, Baton Rouge, LA, 1974).
- Russell, E. War and Nature: Fighting Humans and Insects with Chemicals from World War I to Silent Spring (Cambridge University Press, Cambridge, UK, 2001).
- Lowdermilk, W “The reclamation of a man-made desert” (1960) reprinted in Man and the Ecosphere: Readings from Scientific American (Ehrlich, PR, Holdren, JP & Holm, RW, eds), 218–227 (WH Freeman, San Francisco, 1971).
- Love, RM. “The rangelands of the western United States” (1970) reprinted in Man and the Ecosphere: Readings from Scientific American (Ehrlich, PR, Holdren, JP & Holm, RW, eds), 228–235 (WH Freeman, San Francisco, 1971).
- Editorial comments on Lowdermilk’s and Love’s articles in Man and the Ecosphere: Readings from Scientific American (Ehrlich, PR, Holdren, JP & Holm, RW, eds), 202–203 (WH Freeman, San Francisco, 1971).
- Holdren, JP & Ehrlich, PR. Human population and the global environment: population growth, rising per capita material consumption, and disruptive technologies have made civilization a global ecological force. American Scientist 62, 282–292 (1974).
- Westman, WE. How much are nature’s services worth? Science 197(4307), 960–964 (1977).
- Costanza, R et al. The value of the world’s ecosystem services and natural capital. Nature 387(6630), 253–260 (1997).
- Pimm, SL. The value of everything. Nature 387(6630), 231–232 (1997).
- Daily, G & Ellison, K. The New Economy of Nature: The Quest to Make Conservation Profitable (Island Press, Washington DC, 2002).
- Daily, G, ed. Nature’s Services: Societal Dependence on Natural Ecosystems, xv (Island Press, Washington DC, 1997).
- Mooney, HA & Ehrlich, PR in Nature’s Services (Daily, G, ed), Ecosystem services: a fragmentary history, 11–17 (Island Press, Washington DC, 1997).
- Costanza, R et al. Managing our environmental portfolio. BioScience 50(2), 149–155 (2000).
- Wheeler, TB. In Reservoir Hill, greening stems blight. Baltimore Sun, 1, 10 (July 14, 2011).
- Friends of the Spit [online]. www.friendsofthespit.ca/fos_about.htm.
- Bennett, EM, Peterson, GD & Levitt, EA. Looking to the future of ecosystem services. Ecosystems 8, 125–132 (2005).
- Jacobs, J. The Death and Life of Great American Cities (Random House, New York, 1961).