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| Abstract Title:
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| Effects of elevated nitrogen dioxide and carbon dioxide on the growth of Sugar Maple and Hemlock seedlings
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| Graduate Student Presenter:
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Allyson SD Eller
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| Name of the Author(s) and Affiliation(s):
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Allyson SD Eller, Cornell University; Krista L McGuire, University of Michigan; Jed P Sparks, Cornell University
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Human activities are increasing the concentrations of carbon dioxide (CO2) and nitrogen dioxide (NO2) in the atmosphere. These gases are ecologically important due to their potential effects on plant productivity. For example, CO2 generally has a positive effect on plant growth, but the magnitude can be altered by nitrogen availability. Further, NO2 and other forms of reactive nitrogen have been shown to have a positive or negative impact on plant growth depending on the concentration in the atmosphere and the nutritional status of the plant. This bifunctional effect of reactive nitrogen appears to be because reactive N gases can simultaneously produce nutritional compounds useful to the plant (e.g., nitrate) and act as an oxidant damaging cell membranes. This study examined the effects of NO2 on plant productivity alone and in combination with elevated CO2. Sugar maple and eastern hemlock seedlings were fumigated in open-topped chambers for two years in a fully factorial experiment. The addition of CO2 increased the total biomass of hemlock seedlings, but this response was eliminated in the presence of NO2. Maple biomass was decreased by NO2, but CO2 ameliorated the effect. No treatment altered the above and belowground biomass allocation in either species, but CO2 caused thicker leaves in maple seedlings. These results highlight the variability of growth responses to elevated CO2 and NO2 across species and underscore the need for examining the responses of multiple species and functional groups when assessing the responses of vegetation to changes in atmospheric chemistry.
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