If the planet's biota -- all the plants and animals and microorganisms -- sent a bill for their 1997 services, the total would be $2.9 trillion, according to an analysis by biologists at Cornell.

For the United States alone, the tab for economic and environmental benefits of biodiversity would be $319 billion, the biologists report in the December issue of the journal BioScience. (Vol. 47 pp. 747-757).

"When you compare our spending (to preserve biodiversity) to the benefits we reap, we're really getting a bargain," said David Pimentel, the professor of ecology who led eight graduate students in Cornell's College of Agriculture and Life Sciences through a rigorous analysis to arrive at what he terms a conservative estimate. A previous study had valued the world's ecosystem services and natural capital at $33 trillion a year.

The Cornell study counted natural services of a diverse biota, such as organic waste disposal, soil formation, biological nitrogen fixation, genetic resources to increase food crop and livestock yields, biological control of pests, plant pollination, pharmaceuticals and other nature-based products, ecotourism, and sequestration of carbon dioxide that otherwise would contribute to global warming (see "Biotic Invoice," attached).

The biotic beneficence would be even greater, the Cornell biologists observed, if human society took full advantage of nature's genetic offerings. For example, cultivating perennial cereal grains that can be harvested continuously for 4 to 5 years without tilling and replanting -- in place of annual grains whose energy-intensive spring and fall tilling exposes soil to wind and water erosion -- could reduce erosion as much as 50 percent, saving $20 billion worth of soil and $9 billion in tractor fuel every year in the U.S., according to the analysis. Genes for perennial cereal grains already exist in wild plant species, they said, estimating the worldwide value of a perennial grain system at $170 billion a year.

"We hope assessments such as this," Pimentel said, "can serve as a foundation to develop strategies and policies to preserve biological diversity and maintain ecosystem integrity. All these services to humanity are possible only because our planet is such a diverse place. Every species that's lost diminishes that vast resource and makes us all poorer for the loss."

Biotic Invoice

Estimated annual economic benefits of biodiversity in the United States and worldwide

Source: David Pimentel, Christa Wilson, Christine McCullum, Rachel Huang, Paulette Dwen, Jessica Flack, Quynh Tran, Tamara Saltman, Barbara Cliff

College of Agriculture and Life Sciences, Cornell University