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ECOLOGIST STUDIES PLANTS FOR GLOBAL-WARMING CLUES.

Byline: David Graham The San Diego Union-Tribune

On a remote slope in the Southern California back country, ecologist Walt Oechel kneels in the mud, intently scrutinizing the greenery of a chamise plant.

In its leaves, he hopes to read the future.

What messages Oechel deduces from the chamise, a shrub indigenous to the region's chaparral, may turn out to have great significance for mankind.

Oechel, the director of San Diego State University's Global Change Research Group, wants to look ahead to the mid-21st century to learn how these and similar ecosystems might grow as the air becomes increasingly rich in carbon dioxide.

Many scientists fear that accumulating carbon dioxide is trapping the sun's heat, contributing to global warming and leading to a host of unpredictable climate changes.

Where conservation and treaties have failed to curb carbon dioxide levels, Oechel believes the chaparral might succeed. Plants use carbon dioxide as a nutrient in photosynthesis. In a carbon dioxide-rich future, Oechel theorizes, chaparral may grow bulkier, sopping up even greater amounts of the gas.

Here, atop an anonymous mountain north of Lake Henshaw, Oechel is testing a hypothesis that suggests semi-arid ecosystems across the globe, like California's chaparral, may absorb so much carbon dioxide that they could mitigate global warming.

"We may find we can use the natural system to reduce carbon dioxide," Oechel said, "and it may produce a beneficial environmental effect."

Elsewhere, researchers have begun to investigate how wheat, cotton, commercial forests, even tundra and desert ecosystems, might change with more atmospheric carbon dioxide.

All of the changes, of course, will likely not be benign. The additional foliage Oechel imagines for Southern California may pose perils as well. Larger, denser stands of growth in a drier climate could, for example, fuel bigger, more intense wildfires.

To predict the future more precisely, Oechel is trying to mimic it. At SDSU's Sky Oaks Research Facility, in a pristine patch of wooded country near the border separating San Diego and Riverside counties, Oechel is running a novel experiment.

He and colleagues have built a testing structure that resembles nothing so much as the Druid monument Stonehenge. Instead of stone pillars, however, there are 36 vertical metal tubes set in a 50-foot-wide ring on a hillside. The roar of a turbine engine shatters the tranquillity of a winter afternoon as carbon dioxide-enriched air is forced through the tubes and over the fledgling vegetation.

Inside the ring, stands of chamise and caenotheus shrubs, herbs and wildflowers are exposed to air loaded with 550 parts per million of carbon dioxide, the amount researchers believe will saturate the air in 2050. This is double the level at the turn of this century. Today, the air has about 360 parts per million.

The test runs continuously, and because it is outdoors, computer orchestration of the experiment is essential. Weather vanes transmit information about wind direction and speed to a computer, which opens and closes different valves to channel a constant flow of carbon dioxide gas over the plants. The experiment runs outside to simulate the natural environment as much as possible, including the effects of drought and wind, animals and birds, even microbes in the soil.

Since the test began in December, experiments show the test plants are growing faster than nearby wild ones.

Oechel wants to know just how much the physiological capacities of plants can be stretched. Experiments suggest that plant storage capacity could rise by more than 50 percent.

CAPTION(S):

PHOTO

Photo (1) Project manager Walt Oechel checks the seal on one of the carbon-dioxide flooded greenhouses for research conducted by San Diego State University. (2) Oechel stand at the experiment site where plants are being tested for the amount of carbon dioxide they can store. Associated Press
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Copyright 1996, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Publication:Daily News (Los Angeles, CA)
Date:Mar 3, 1996
Words:624
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