News Release

MADISON, WI, MARCH 10, 2008 -- The well-documented, unprecedented rise in global atmospheric carbon dioxide (CO₂) concentration has the strong potential to make invasive plants even more aggressive as they move into agricultural ecosystems. USDA-ARS scientists Hugo Rogers, Brett Runion, Stephen Prior, Andrew Price, and Allen Torbert working in the Mid-South Area at the National Soil Dynamics Laboratory in cooperation with an Auburn University scientist, Dean Gjerstad of the School of Forestry and Wildlife Sciences, have explored the responses of two of the worst invasives - purple and yellow nutsedge - to increased atmospheric CO₂. Findings, published in the March-April Journal of Environmental Quality, suggest that these species, purple more than yellow nutsedge, may be even more invasive in a future high CO₂ world.

The lead author of the work, Hugo Rogers, stated “that both purple and yellow nutsedges benefited from elevated atmospheric CO₂ and that, overall, purple was more responsive to CO₂ enrichment than yellow. These findings suggest the potential for both of these nutsedges to become more invasive, causing even larger problems for farmers, purple more than yellow, in a future high CO₂ world.”

In 2005 the responses of the two species were tested by growing them under CO₂ enriched conditions for 2.5 months. Both exhibited positive responses to elevated atmospheric CO₂, making them potentially more competitive with other plants, including crops, and thus more invasive.

Historically, the severity of the adverse effects of invasive plants on farming, forestry, and natural ecosystems have been overlooked. The magnitude of these plant invasions is now apparent and they threaten biodiversity throughout the world. This serious issue starts with the introduction of a noxious species from another part of the globe, then establishment within indigenous plant systems leading to competition with desirable native species or crops which are then overrun and smothered out.

The National Invasive Species Information Center of the USDA National Agricultural Library website (http://www.invasivespeciesinfo.gov/plants/main.shtml) describes invasive plants as adaptable and aggressive with high reproductive potential. In his 2002 book, Biological Invasions: Economic and Environmental Costs of Alien Plant, Animal, and Microbe Species, Dr. David Pimentel reports losses (caused by these invading plants) to U.S. farms and forests to be upwards of $34 billion every year resulting from drastically reduced yields and expensive control measures.