Magazine article Science News

Ecologists Go to Town; Investigations in Baltimore and Phoenix Forge a New Ecology of Cities

Magazine article Science News

Ecologists Go to Town; Investigations in Baltimore and Phoenix Forge a New Ecology of Cities

Article excerpt

It was a typical field trip. A group of ecologists inside a Chevy Suburban worked on a laptop computer and talked as they bounced along the gravel road that would end up 14 hours later at a small field station in northern Alaska. As they traveled, they discussed what areas to add to the Long-Term Ecological Research (LTER) network--the exclusive list of sites selected for prolonged scrutiny by U.S. ecologists.

The traditional choice would have been a virtually untarnished spot--one that had thus far managed to escape much human interference.

"The draw for ecologists has been the natural environment," says James R. Gosz, an ecologist at the University of New Mexico in Albuquerque who heads the committee overseeing the LTER network. But Gosz and the others riding through the Alaskan wilderness to the Toolik Lake LTER site 8 years ago recognized that people are part of the environment and that ecologists needed to start examining the landscape most influenced by people--the city.

Those conversations in the wilderness, Gosz says, ultimately resulted in the November 1997 addition of Baltimore, Md., and Phoenix, Ariz., sites to the LTER network.

These choices mark a new direction in ecology. "Ecology is the science of the relationship among organisms and their environment. What could be more ecological than studying humans and their environment? For a large number of people in this world, that means humans in the context of cities," says James A. MacMahon, an ecologist at Utah State University in Logan and president of the Ecological Society of America.

The new sites join a network of research areas designed to answer questions about ecological processes that occur over long periods. The National Science Foundation (NSF) began the LTER program in 1980 with six sites representing such ecosystems as lakes, forests, and prairies. Now, with the addition of Baltimore and Phoenix, the network has expanded to 20 sites.

Part of every LTER site's research program is designed to answer five core questions, Gosz says. What controls the growth of plants? What causes plant and animal populations to vary over time? What happens to the organic matter that plants produce? How do inorganic nutrients move through soil and water? How do disturbances such as fires, drought, or timber cutting affect the biology of the system?

"Research at these long-term sites is challenging long-held perceptions about ecological systems," says ecologist Scott L. Collins, who over sees the LTER program for NSF. For example, he says, researchers at the Harvard Forest LTER station in Massachusetts have shown that dramatic disturbances, such as hurricanes, may have little long-term effect, whereas subtle, human-induced changes in the nitrogen cycle are altering the basic ecosystem processes in the forest.

Unlike most ecological research projects, which are funded for only 3 years, LTER programs are initially funded for 5 or 6 years, at the end of which the funding is usually renewed. As a result, scientists now have more than 18 years' worth of information on some of the oldest LTER sites. To kick off the Baltimore Urban LTER project and the Central Arizona-Phoenix Urban LTER project, NSF provided each with $875,000 for the first year and $700,000 for each of the succeeding 5 years.

"The long term really gives you a different way of thinking about your project," says Collins. "You can do more risky experiments."

He adds, "Long-term research allows you to understand surprises. If you get a surprise year--double the amount of rain, or half the amount of rain, or an outbreak of grasshoppers--if you don't have a lot of time, you don't get to follow that very well."

To organize their inquiries about cities, the investigators at both urban LTER sites plan to use a popular method for figuring out how ecosystems vary from place to place and over time.

In the past, while studying an ecosystem such as a forest or field, ecologists drew a boundary around it and assumed the region inside was uniform, says Steward T. …

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