News Archive

posted 09/05/02

International Scientists Converge at Rainforest in the Arizona Desert to Test El Niño's Impact on Ecosystem
Columbia university biosphere 2 rainforest site for drought experiment -- collaborative global climate change experiment underway

TUCSON -- In a major collaborative research initiative, an international group of 14 scientists from a range of disciplines have gathered at Columbia University Biosphere 2 Center for an El Niño experiment in the Laboratory's Rainforest -- an acre tropical habitat, supporting a complex patchwork of vegetation that is a functional model of the Amazon Rainforest.

El Niño years bring hot, dry weather to the Amazon region, where nearly half of Earth's undisturbed evergreen forest is found. These forests account for about 10 percent of the planet's primary land productivity and a similar fraction of carbon dioxide (CO2) consumption. Understanding the Amazon Rainforest response to such climate variations is of particular importance to climate change science — as well as those writing climate change policy.

This most recent of four drought experiments simulates the droughts that may follow this year's El Niño in the equatorial Pacific Ocean. The experiment, which began in winter 2000 and restarted Monday, September 23, 2003, will continue until late November.

"The previous Rainforest experiments have been so informative that scientists from various disciplines have come out to collaborate," said Barry Osmond, president and executive director, Columbia University Biosphere 2 Center. "Nowhere else on Earth can this be done at this scale with such precise control. By far, Biosphere 2 is the largest-controlled environment apparatus available for experimental climate science," Osmond said.

Dr. Guanghui Lin

Click here to see a short video about Dr. Guanghui Lin's research.

Overall, lead researchers Dr. Guanghui Lin of Columbia and Dr. Joseph Berry of Carnegie Institution's Dept. of Global Ecology are investigating the effect of a dramatic decrease in precipitation to the carbon storage (sink) and carbon release (source) relationship within this 11-year old man-made rainforest. In addition, seven research teams with new instruments for remote sensing of leaf responses and for atmospheric analysis are participating. The teams include: remote sensing, ecosystem productivity, on-line stable carbon discrimination, trace gas fluxes, water budget, soil properties and isoprene levels. "This is the first time that such a comprehensively observed controlled experiment has been done," Osmond said. "Effectively, the rainforest will be stressed, but in intensive care," Osmond noted.

"This experiment offers a unique opportunity for scientists to not only focus on their specific measurements, but also the ability to compare and share data sets that they otherwise would not have time to conduct," said Dr. John Grace, department head, Institute of Ecology and Resource Management, University of Edinburgh, Scotland.

The collaborative research approach was first envisioned in the mid-1990s by Dr. Wallace Broecker, a noted Columbia Scientist, who was one of the first to champion the need and value of the Biosphere 2 Lab for climate change science.

Initially, the experimental drought in the Biosphere 2 Rainforest is followed with heavy rains. Then, the mini ecosystem is allowed to dry out for at least 28 day with no further precipitation. Recent long-term studies suggest that these ecosystems are globally important carbon sinks. But, they have experienced substantial inter-annual climate variability in recent decades -- the result of frequent El Niño episodes. Scientists debate how much of the CO2 from the burning of fossil fuels is absorbed by rainforests and how the absorption rate changes with inter-annual climate variability. By absorbing CO2, the rainforest slows the increase of atmospheric CO2, thereby slowing global warming.

The only way to predict the impact of such episodes on rainforest ecosystems is by mathematical models designed to simulate basic biological processes. Validating such models is critical, but extremely difficult in the real world where controls are absent. Biosphere 2's Rainforest provides not only the control capability, but also a representative ecosystem community that can be exposed to the same conditions during El Niño years. Using Biosphere 2's unique rainforest, scientists can now validate their modeled results.

Scientists and technicians collaborating include: Glenn Fitzgerald, U.S. Water Conservation Lab, Phoenix, AZ., Marc-Thorsten Hütt, Darmstadt University of Technology, Institut fur Botanik der TU Darmstadt, Schnittspahnstr, Germany, Gennady Ananyev and Zbigniew Kolber, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ., Jeannie E. Triol McLain, U.S. Dept. of Agriculture, Tucson, AZ., Mike Trudeau, University of Colorado, Boulder, Jennifer Funk, Dept. of Ecology and Evolution, State University of New York, Stony Brook, Caroline Nichol, Institute of Ecology and Resource Management, University of Edinburgh, Leif Hendriks, Surface Optics Corporation, San Diego, Christopher Small, Columbia University's Lamont-Doherty Earth Observatory, and from Biosphere 2 Center -- Uwe Rascher, Achim Walter, Ed Bobich, Karl Bil', Danielle Pierce, Tiffany Morris, Joost van Haren, Emiliano Pegoraro.

Biosphere 2 Center is Columbia University's 250-acre Arizona campus, located outside of Tucson, devoted to deepening understanding of earth systems vital to informed leadership of the planet. Its 3.1-acre, glass-enclosed, research laboratory allows systems-level research on the science of sustainability. Academic programs in earth systems for high school, undergraduate and graduate students as well as educational programs for 180,000 annual visitors and local school children are part of the Center's continued commitment to public outreach and education.