PARENT SESSION
Poster Session #50: Climate Change.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Ragweed pollen production in respons to urban-induced CO₂/temperature gradients.

Ziska, Lewis^*,1, Gebhard, Dennis², Frenz, David², Faulkner, Shaun¹, Singer, Benjamin³, Straka, James³, ¹ USDA-ARS, Beltsville, Maryland² Surveillance Data Incorporated, St Louis Park, Minnesota³ Macalester College, St. Paul, Minnesota

ABSTRACT- Little information is available regarding how climate change will alter the life cycle of plant species which affect human health. As a means of evaluating the impact of climate change on such species, we tested whether urbanization per se provided a stable gradient of increased CO₂ concentration and air temperature that could be used to monitor the in situ response of common ragweed, the principle Fall allergen. During the growth cycle of ragweed, average daily (24 h) values of CO₂ concentration and air temperature were increased by 30 and 31% and 1.8-2.0^oC (3.4-3.6^oF) from a rural to an urban site for 2000 and 2001, respectively. Ragweed grown at urban and suburban locations reached various phenological milestones prior to plants at the rural location and produced significantly greater (2-3x) above ground biomass by flowering. The increase in biomass at anthesis was directly related to earlier and greater amounts (~4x) of ragweed pollen production. Data from these experiments indicate that: (1) differential response of ragweed to regional, urban-induced climatic change may have public health consequences; and, (2) urbanization may provide a stable CO₂/temperature gradient that could be used as a low-cost alternative to current experimental methodologies evaluating plant responses to climate change.

KEY WORDS: Climate change, ragweed, public health, carbon dioxide