DISSERTATION RESEARCH: Changes in Ectomycorrhizal Fungal Communities Along a Nitrogen Deposition Gradient and Their Consequences for Host Tree Performance

外生菌根真菌是世界各地森林土壤中数量丰富、种类多样、具有重要生态意义的微生物。通过与树根形成的密切联系，它们将从土壤中获得的必需营养物质与树木通过光合作用获得的碳进行交换。在营养有限的森林中，这种方式可以大大促进树木的生长，使外生菌根真菌群落成为森林生产力的重要决定因素。化石燃料燃烧产生的越来越多的氮沉积在美国东北部的森林中。由此导致的酸度、铝的流动性和土壤中N浓度的增加都是可能影响外生菌根真菌群落及其树木宿主的因素。实地研究将利用基于dna的分子技术鉴定物种，并测量它们的丰度和分布在氮污染下的变化。将进行实验室试验，以检查对树木性能的影响。这将有助于更好地了解东北森林外生菌根真菌群落变化的动态和后果。

Ectomycorrhizal fungi are abundant, diverse, and ecologically important microorganisms in forest soils throughout the world. Through intimate connections they form with tree roots, they trade essential nutrients obtained from the soil for carbon acquired by trees through photosynthesis. Tree growth in nutrient limited forests can be greatly enhanced in this manner, making the ectomycorrhizal fungal community an important determinant of forest productivity. Increasing amounts of nitrogen produced by the burning of fossil fuels are being deposited in forests of the northeastern U.S. The resulting increases in acidity, aluminum mobility, and N concentration in soil are all factors that can potentially influence ectomycorrhizal fungal communities and their tree hosts. Field research will identify species using DNA-based molecular techniques and measure changes in their abundance and distribution in response to nitrogen pollution. Laboratory experiments will be conducted to examine consequences for tree performance. This will lead to a better understand of the dynamics and consequences of changes in the ectomycorrhizal fungal communities of northeastern forests.