Located in a fenced off section of Stanford's 1,189-acre Jasper Ridge Biological Preserve, the novel experiment was designed to simulate environmental conditions that climate experts predict may exist 100 years from now: a doubling of atmospheric CO2; a temperature rise of 2 degrees F; a 50 percent increase in precipitation; and increased nitrogen deposition largely a byproduct of fossil fuel burning.
Launched in 1997, the Jasper Ridge experiment was conceived by Mooney and Christopher B. Field, a professor by courtesy in Stanford's Department of Biological Sciences and director of the Carnegie Institution's Department of Global Ecology, also located on the Stanford campus.
"Most studies have looked at the effects of CO2 on plants in pots or on very simple ecosystems and concluded that plants are going to grow faster in the future," said Field, co-author of the Science study. "We got exactly the same results when we applied CO2 alone, but when we factored in realistic treatments warming, changes in nitrogen deposition, changes in precipitation growth was actually suppressed."
To mimic future climate conditions, Field, Mooney and their colleagues mapped out 36 circular plots of land, each about six feet in diameter. Four plots are virtually untouched, receiving no additional water, nitrogen, carbon dioxide or heat. Each of the remaining 32 circles is divided into four equal quadrants separated by underground partitions to prevent roots in one section from invading neighboring tracts. In these smaller quadrants, researchers study all 16 possible combinations of elevated and normal CO2, heat, water and nitrogen.
The plots thicken
The biggest surprise from the study was the discovery that elevated carbon dioxide only stimulated plant growth when
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
5-Dec-2002