DISSERTATION RESEARCH: Combined Effects of Elevated NO2, O3, and CO2 on Plant Growth and Productivity

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The objectives of this study are to determine the single and combined effects of several atmospheric gases likely to increase dramatically in the next century [carbon dioxide (CO2), nitrogen dioxide (NO2), and ozone (O3)] on the leaf physiology and overall growth of sugar maple, eastern hemlock, trembling aspen, and red oak seedlings. The trees are fumigated with elevated (40ppb) or ambient NO2, elevated (560ppm) or ambient CO2, elevated (100 ppb) or ambient O3, and grown in native soil with or without additional soil fertilization. Seedling growth and leaf physiological performance (e.g., photosynthesis, stomatal conductance) will be measured continuously and, at the end of the experiment, total growth of each species will be measured and differences attributed to the exposure to pollution fumigation.Human activities have induced changes in the chemical composition of the atmosphere: the concentrations of CO2, NO2, and O3 have increased and are expected to continue increasing in the future. Plants are both impacted by these gases by altering physiological processes and have the ability to remove gases from the atmosphere and, in some cases, incorporate the carbon and nitrogen from these gases into biomass. Therefore, results from this experiment will increase our understanding of plant productivity in a future atmosphere, how plants may alter the level of gases in the atmosphere, and help to generate a more accurate determination of the carbon-storage potential of trees and ecosystems.