Putting Numbers to Nature


The Natural Capital Project is helping China, home to 1.3 billion people and 10 percent of plant and animal species, find a balance between development and ecosystem protection.

When a Minnesota corn farmer fertilizes his land, he improves his crop yield and his bottom line. But if some of the fertilizer runs off into streams and out into the Mississippi River, that benefit comes at a cost. The nitrogen- and phosphorus-infused water tumbles past 10 states before emptying into the Gulf of Mexico. The gulf’s 7,700-square-mile summertime dead zone is directly linked to upstream fertilizer use.

“Farmers get the value of the crops they grow, but they don’t pay anything for the loss of water quality downstream,” says Institute on the Environment resident fellow Stephen Polasky, an environmental economist in the University of Minnesota’s College of Food, Agricultural and Natural Resource Sciences. Although economists can quantify the monetary impacts to commercial fisheries, the loss of less-celebrated organisms, such as worms, sea stars or zooplank­ton, is rarely factored in.

Enter the Natural Capital Project. A partnership between aca­demia and on-the-ground practitioners, the project is one of the world’s first attempts to mainstream ecosystem services—the very real but often underappreciated “life support” a healthy environment provides, including clean water, clean air, flood control, biodiversity, and the recreational and spiritual benefits of nature.

“We want to bring to bear on the decisions made by firms, indi­viduals and government agencies the underlying values of ecosys­tem services and biodiversity,” explains Polasky, one of the project’s intellectual leaders. “Oftentimes those values, even though important, are not captured in decision making.”

The Natural Capital Project “came together over many beers and chocolate,” says Peter Kareiva, a chief scientist with The Nature Conservancy who co-founded the project with Stanford biology professor Gretchen Daily and Taylor Ricketts of World Wildlife Fund.

Polasky developed InVEST, the software undergirding the project. The software allows users to assign values to various landscape types in a geographic information system (GIS) framework. One can look at a landscape’s present status and model future trends on local, regional or global scales. The model’s output can be biophysical—such as tons of carbon sequestered—or economic.

“Steve Polasky taught us the value of thinking in terms of trade-offs and decision support tools to maximize the benefits of land use decisions,” says Kareiva.

The Natural Capital Project began turning theory into practice in 2006, calculating values for carbon sequestration and river basin conservation in the Yunnan Province of China, hydropower and timber products in Tanzania’s Eastern Arc Mountains, and similar projects in California, Oregon and Hawaii. Polasky, who helped bring the IonE on board as a Natural Capital Project partner this year, led a pilot study examining a Minnesota farmer’s conservation-minded land use decisions, such as adding streamside buffers to a farm, as a “proof of concept.” The results were predictable.

“If you just look at commodity returns—traditional economic calculations—doing those conservation practices didn’t add up, since you’re taking land out of agricultural production,” says Polasky. “But if you added in the value of ecosystem services, all sets of users end up many times better off under conservation scenarios. It really points out the importance of incorporating the full set of consequences into decision making, instead of the partial list that typically gets considered.”

Since then, Natural Capital projects have influenced land use decisions around the world. In Hawaii, Kamehameha Schools used InVEST to analyze trade-offs associated with three land use options—biofuel feedstock, residential development, or diversified agriculture and forestry—for 10,500 acres of watershed land they owned on Oahu. Although residential development would yield more income, it would also cause declines in both carbon stocks and water quality. The schools opted to develop the land using diversified sustainably managed agriculture and forestry, which increases carbon stocks and helps protect the watershed.

In the long run, the goal of the Natural Capital Project is to make considering ecosystem services in land use decisions mainstream, says Polasky. That takes working with all segments of society to show that preserving the environment does not have to harm someone’s livelihood. In many cases, it may just help.

Houston-based freelance writer and photographer Wendee Holtcamp has published in magazines such as Scientific American, OnEarth, National Wildlife, and Smithsonian. She is also Animal Planet’s news blogger.