DISSERTATION RESEARCH: Effects of Soil Nitrogen Enrichment on the Chemical Mediation of Multi-Trophic Interactions

虽然大多数温带陆地生态系统仍然氮有限，但人类活动的氮输入正在迅速增加。该项目将研究氮富集对植物-食草动物和食草动物-捕食者相互作用的影响。土壤氮富集可能会影响这种相互作用，通过植物生产力的变化，营养品质，和防御化学。这些对植物的直接影响反过来又可能影响到食草动物和捕食者。该项目研究了化学防御的入侵植物（达尔马提亚蟾蜍，柳穿鱼，玄参科），一种专门的昆虫草食动物，存储这些植物防御化合物（蟾蜍落叶，Calophasia lunula，夜蛾科）和几种无脊椎动物捕食者之间的相互作用。这些相互作用将在温室和田间实验中进行研究，在这些实验中，植物在不同水平的氮添加下生长。研究结果将有助于理解土壤氮素富集可能影响这种相互作用的明确机制。该项目代表了对这种入侵植物的化学生态学的第一次研究，以及已经引入来管理该物种的生物控制昆虫。入侵植物对本地生物多样性构成了重要威胁，氮沉降可能会促进这些物种入侵栖息地的侵略性。这项研究的信息将为改善作为牧场杂草的具有生态和经济意义的入侵植物的生物防治工作提供见解。此外，这项研究的更广泛的影响包括促进研究人员和土地管理者之间的合作，以及教育公众有关环境变化和植物入侵。

While most temperate terrestrial ecosystems remain nitrogen limited, nitrogen inputs from human activity are increasing at a rapid rate. This project will examine the influence of nitrogen enrichment on plant-herbivore and herbivore-predator interactions. Soil nitrogen enrichment may influence such interactions through changes in plant productivity, nutritional quality, and defensive chemistry. These direct effects on plants, in turn, may affect both herbivores and predators. This project examines interactions between an invasive plant that is chemically defended (Dalmatian Toadflax, Linaria dalmatica, Scrophulariaceae), a specialist insect herbivore that stores these plant defense compounds (Toadflax Defoliator, Calophasia lunula, Noctuidae), and several invertebrate predators. These interactions will be investigated in greenhouse and field experiments in which plants are grown under varying levels of nitrogen addition. The results will contribute to understanding the explicit mechanisms by which soil nitrogen enrichment may influence such interactions. This project represents the first study of the chemical ecology of this invasive plant and a biological control insect that has been introduced to manage this species. Invasive plants pose an important threat to native biodiversity and the aggressiveness of these species to invade a habitat may be facilitated by nitrogen deposition. Information from this research will provide insight for improving biocontrol efforts for an invasive plant that has ecological and economic significance as a rangeland weed. Further, the broader impacts of this research include fostering collaborations between researchers and land managers as well as educating the public about environmental change and plant invasions.