Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
February 10, 2005
Ecosystem response to climate change overvalued, study says
Scientists trying to predict the effects of climate change on ecosystems may be overestimating the responses, according to new research by a University of Guelph professor.
The findings of a six-year study headed by ecologist John Klironomos appear in the Feb. 10 edition of Nature magazine. He and collaborators from Guelph, the University of California at Riverside and the University of Montana were the first to test a common scientific assumption about how rising levels of carbon dioxide (CO2) will influence ecosystems.
“Scientists around the world are working to understand the changes in structure and function that will occur in ecosystems 100 years from now in response to this increase,” Klironomos said.
Atmospheric CO2 is expected to continue to rise at an annual rate of 1.5 parts- per- million for the next century. A typical research method is to expose current ecosystems to the predicted increases and then make comparisons. “The common assumption is that a single-step increase will produce changes similar to a gradual increase over several decades,” he said.
The researchers tested this premise by observing the response of plants and their mycorrhizal fungal communities to changing CO2 concentrations over a span of six years. The fungi used in the study were selected because they are dependent on plant photosynthate for survival and are therefore affected by changes in CO2 concentration. They also grow and reproduce quickly and are easily contained.
“You can’t bring a forest into a lab,” Klironomos said. “But with fungi, you can keep entire communities in little pots. We could expose them to various CO2 levels, and because they have a quick turnaround time, we could really compare abrupt versus gradual responses. That is really tough to do in most ecosystems.”
During the course of the study, 21 generations of plants and fungal communities were examined. It was discovered that when there was an abrupt change in climate, the diversity and functioning of the first generation were significantly altered, but there was little change in subsequent generations. In addition, fungi exposed to gradually increasing CO2 levels were much less affected. In fact, diversity and functioning in these communities were similar to those under ambient conditions.
Klironomos said additional research should be conducted in other models and in intact ecosystems to quantify the observed responses. “As in most other published research, this study tells us ecosystems will alter in response to environmental change. But, while we should worry about climate change, we should be careful when interpreting the magnitude of responses to environmental change that is more abrupt than what would occur naturally.”
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