CAREER: Composition, Internal Cycling and Losses of Dissolved Organic Nitrogen Along a Temperate Forest Fertility Gradient

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Nitrogen (N) is the nutrient element most limiting to plant growth and forest productivity in temperate regions. Only recently, scientists have recognized that plants have the potential to acquire organic forms of N from the soil, and that leaching of dissolved organic N (DON) contributes significantly to the loss of N from forest ecosystems. This research project will determine the contribution of DON to tree nutrition across a range of temperate forest ecosystems, will characterize the chemical composition of DON leaching from forests, and will strive to better understand the environmental controls over the production, internal cycling, and loss of DON in forests. To accomplish these goals plant uptake, DON composition, internal cycling, and losses of DON will be compared across a series of forest ecosystems in Michigan that vary systematically in fertility, tree species composition, and productivity. These forested experimental sites also will serve as the foundation for a series of teaching activities designed to introduce concepts of ecosystem science and sustainable forestry to undergraduate students and minority high school students.A better understanding of the form in which N is cycled (organic vs. mineral) has important implications for managing forest productivity, understanding the response of forest ecosystems to anthropogenic N deposition, and understanding the impacts of N leaching on surrounding wetlands, rivers and groundwater. The teaching component of this project will convey fundamental principles of ecosystem science and sustainable management to the next generation of land managers.