University of Minnesota
http://www.umn.edu/
612-625-5000
Environment

New study shows suburban plants play important role in trapping carbon

NASA-funded study is a first step toward quantifying the role of vegetation in extensive developed areas such as suburbs

June 27, 2012

Media note: For photos of the researchers and an aerial view of the suburban landscape studied, visit: http://flic.kr/s/aHsjAfNmZu

Trees and other plants in the wild play an important role in counteracting climate change by trapping carbon dioxide released from burning fossil fuels. New research from the University of Minnesota and UC Santa Barbara shows that suburban vegetation play an important role in net CO2 exchange – with different plants contributing to reducing CO2 by different amounts.

Emily Peters, a postdoctoral fellow with the university’s Institute on the Environment and Joe McFadden, an associate professor in the Department of Geography at UC Santa Barbara, published their findings in the current issue of the Journal of Geophysical Research – Biogeosciences.

“Our study is the first to clearly show how much vegetation can change the seasonal pattern of suburban CO2 exchange,” Peters said. “We know cities and suburbs are net emitters of CO2 due to fossil fuel emissions, and vegetation cannot offset this completely. However, our study shows that vegetation is an important player in suburban CO2 exchange, and can even cause the suburban landscape to be a CO2 sink in summer.”

Placing several sensors high above the ground in a St. Paul suburban neighborhood, Peters and McFadden set out to record tiny changes in CO2, temperature, water vapor and wind. The researchers found that for nine months of the year, the suburban landscape was a net source of CO2 to the atmosphere. During the summer, however, suburban greenery absorbed enough CO2 to balance out fossil fuel emissions within the neighborhood. Peak daily uptake was at the low end of that which would be typical of a hardwood forest in the region.

The CO2-trapping activity of the vegetation differed by type, the study found.

“Lawns’ peak carbon uptake occurred in the spring and fall, because they are made up of cool-season grass species that are stressed by summer heat,” said Peters, “while trees had higher CO2 uptake throughout the summer.” Evergreen trees maintained their CO2 uptake longer than deciduous trees did because they keep their leaves year-round.

The study was funded by NASA and is a first step toward quantifying the role of vegetation in extensive developed areas such as suburbs, which are the parts of urban areas that are growing most rapidly in the country. Potential uses for this type of research include urban planning, where land use and vegetation choices are major decisions, and policy decisions based on reducing greenhouse gases.

The University of Minnesota's Institute on the Environment discovers solutions to Earth’s most pressing environmental problems by conducting transformative research, developing the next generation of global leaders and building world-changing partnerships. Learn more online at www.environment.umn.edu.

Twin Cities Campus: