"Nature's services are the conditions and processes through which natural ecosystems support and fulfill human life," Daily said in an introductory speech at the session. These services are the life support functions normally performed by ecosystems, such as purification of air and water; detoxification and recycling of wastes; generation and maintenance of soil fertility; pollination of crops and other plants; regulation of climate; and mitigation of weather extremes like flood or drought.
In the process, ecosystems also provide goods like seafood and timber, whose harvest and trade represent an important and familiar part of the human economy. And ecosystems support the vast diversity of life, the species that are sources of key ingredients of our agricultural, pharmaceutical and industrial enterprises.
"Humanity came into being after most of these services had been in operation for hundreds of millions to billions of years," said Daily. "They are so fundamental as to make them both easy to take for granted and hard to imagine disrupting beyond repair, as human activity threatens to do today."
Daily, who is Bing Interdisciplinary Research Scientist in Stanford's Department of Biological Sciences, has been working to foster collaboration among academic scientists and business leaders to develop workable and economically profitable ways of incorporating ecosystem service values into decision-making. "So far this effort has been very promising," she said. "Everyone has a stake in finding fair and efficient ways of achieving a balance in human activities so that Earth's life support systems are protected. The practical experience and expertise of leaders in the private sector is crucial to the success of this effort."
One example of that collaboration is the AAAS session: Its roster included top ecologists such as Daily, Oregon State's Lubchenco, Stanford's Paul Ehrlich and Norman Myers of Oxford, with Columbia University economist Geoffrey Heal, Stanford policy expert Donald Kennedy and Rob Horsch of Monsanto Co. Daily also is editor of a new book, Nature's Services (Island Press, 1997), that synthesizes scientific understanding of how these services are provided, how much they are being disrupted by human activities, and how important they are to society. The book is written to be accessible to a lay audience and features contributions from more than 30 distinguished economists and natural scientists.
An ecosystem on the moon
"One way to think about the importance of these goods and services is to imagine trying to set up a happy life on the moon,"Daily said at the AAAS session. "Say you had one year to plan your departure from Earth - what would you bring with you?
"Assume for the sake of argument that the moon miraculously already had some of the basic conditions for supporting human life, such as an atmosphere, a climate and the physical structure of soil similar to those on Earth - although we know that life plays a powerful role in shaping these conditions," she said. "After inviting your best friends and packing your prized possessions, the big question would be, Which of Earth's millions of species do you need to take with you to make that happy life possible?"
Tackling the problem systematically, a hypothetical moon colonist could first choose from among all the species exploited directly for food, drink, spices, fiber and timber products, medicines, various industrial products (such as waxes, lac, rubber and oils) and so on. "You might want to throw in some house and garden plants, a few trees from which to hang a hammock or swing, and probably some animals that you wouldn't want your kids to miss," she said. Even being selective, this list could amount to hundreds or even thousands of species.
The space ship would be filling up before the colonists even began adding the species crucial to supporting those at the top of the list: the bacteria, fungi and small animals that help make soil fertile and break down waste and dead organic matter; the birds, bats and insects that pollinate the flowers; the grasses, herbs and trees that hold the soil in place, regulate the hydrological cycle, supply food for animals and so on.
"Without these, you wouldn't be able to produce crops for food or forests for timber and other products, not to mention the spectacular landscapes that provide intellectual and aesthetic stimulation and lift the human spirit," she said.
Which are these unsung heroes? No one knows precisely which - nor even approximately how many - species are required to sustain human life. "Even determining which species are critical to the functioning of a particular ecosystem service is no simple, Sunday-afternoon task," Daily said. She used the case of soil fertility as an example. Soil organisms are crucial to the chemical conversion and physical transfer of essential nutrients to higher plants. The abundance of soil organisms is absolutely staggering: Under a square-yard of pasture in Denmark, for instance, the soil was found to be inhabited by roughly 50,000 small earthworms and their relatives, 50,000 insects and mites, and nearly 12 million roundworms.
"And that is not all," she said. 'The number of soil animals is tiny compared to the number of soil microorganisms: a pinch of fertile soil may contain over 30,000 protozoa, 50,000 algae, 400,000 fungi and unknown numbers of types of bacteria, with billions of individuals in each species.
"Which to bring to the moon? Many of these species have never been subjected to even cursory inspection: no human eye has ever blinked at them through a microscope, No human hand has ever scratched out a name or description of them, and most human minds have never spent a moment's reflection on them," Daily said. "Yet the sobering fact of the matter is, as famed ecologist Edward O. Wilson put it: They don't need us, but we need them."
Ecosystem services operate on such a grand scale and in such intricate and little-explored ways that most could not be replaced by technology, she said. "Ecosystem services are absolutely essential to civilization; they are priceless. Yet their lack of a price - they are typically not traded in economic markets - has contributed to a widespread lack of awareness of their very existence, and to a corresponding misimpression that the ecosystems that supply them lack value. "
"Just as one cannot capture the full value of a human life in economic terms, it would be absurd to try to estimate the value of nature in strictly economic terms," Daily said. "But estimates of the lower-bound, marginal value of nature's goods and services - in the trillions of dollars - are critical to informing decision-makers."