The full effects of decisions made today about many environmental policies -including climate change and nuclear waste- will not be felt for many years. For issues with long-term ramifications, analysts often employ discount rates to compare present and future costs and benefits. This is reasonable, and discounting has become a procedure that raises few objections. But are the methods appropriate for measuring costs and benefits for decisions that will have impacts 20 to 30 years from now the right ones to employ for a future that lies 200 to 300 years in the future?

Rather than simply disassemble current methodologies, the contributors examine innovations that will make discounting a more compelling tool for policy choices that influence the distant future. They discuss the combination of a high shout-term with a low long-term diescount rate, explore discounting according to more than one set of anticipated preferences for the future, and outline alternatives involving simultaneous consideration of valuation, discounting and political acceptability.

in Hobbs, R. and H. Mooney (eds), Biological Invasions and Global Change, Island Press, 1999 (in press).

Earth Systems: Processes and Issues is the ideal textbook for introductory courses in earth systems science and environmental science. Integrating the principles of the natural sciences, engineering, and economics as they pertain to the global environment, it explains the complex couplings and feedback mechanisms linking the geosphere, biosphere, hydrosphere, and atmosphere. An impressive group of internationally respected researchers and lecturers have brought together a vast wealth of teaching experience to produce this fully integrated environmental textbook. It has been designed for the wide range of courses at the first-year university level which touch upon environmental issues: in earth and atmospheric science, environmental science, biological science, oceanography, geography, civil engineering, and social science. Each chapter includes a reading list of the most important references, and problem sets will encourage students to explore the subject further. This text will favorably influence the future development of environmental studies and earth system science.

Nitrogen fertilization is a substantial source of nitrogen-containing trace gases that have both regional and global consequences. In the intensive wheat systems of Mexico, typical fertilization practices lead to extremely high fluxes of nitrous oxide (N2O) and nitric oxide (NO). In experiments, lower rates of nitrogen fertilizer, applied later in the crop cycle, reduced the loss of nitrogen without affecting yield and grain quality. Economic analyses projected this alternative practice to save 12 to 17 percent of after-tax profits. A knowledge-intensive approach to fertilizer management can substitute for higher levels of inputs, saving farmers money and reducing environmental costs.

Life itself as well as the entire human economy depends on goods and services provided by earth's natural systems. The processes of cleansing, recycling, and renewal, along with goods such as seafood, forage, and timber, are worth many trillions of dollars annually, and nothing could live without them. Yet growing human impacts on the environment are profoundly disrupting the functioning of natural systems and imperiling the delivery of these services.

Nature's Services brings together world-renowned scientists from a variety of disciplines to examine the character and value of ecosystem services, the damage that has been done to them, and the consequent implications for human society. Contributors including Paul R. Ehrlich, Donald Kennedy, Pamela A. Matson, Robert Costanza, Gary Paul Nabhan, Jane Lubchenco, Sandra Postel, and Norman Myers present a detailed synthesis of our current understanding of a suite of ecosystem services and a preliminary assessment of their economic value. Chapters consider:

• major services including climate regulation, soil fertility, pollination, and pest control
• philosophical and economic issues of valuation
• case studies of specific ecosystems and services
• implication of recent findings and steps that must be taken to address the most pressing concerns

Nature's Services represents one of the first efforts by scientists to provide an overview of the many benefits and services that nature offers to people and the extent to which we are all vitally dependent on those services. The book enhances our understanding of the value of the natural systems that surround us and can play an essential role in encouraging greater efforts to protect the earth's basic life-support systems before it is too late.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.

Weeds have been a persistent problem in rice since the beginning of settled agriculture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields equivalent to about 50 million tons of rough rice annually.

The papers in this book define the links between the economics of weed control, herbicide use, and weed ecology. The presentations provide a basis for developing a much broader array of weed management tools from which integrated weed management strategies can be designed. Understanding the linkages and developing rational methods are critical in efforts to achieve greater sustainability of rice production.