Disertation Research: Nitrogen-Plant-Insect Interactions: Integrating Via a Net Effects Approach

9423316众所周知，科尔曼氮肥既能增加植物生产力，又能损害昆虫食草动物。某些水平和施肥量可能会增加虫害，从而对植物生产力产生负面影响。这项研究将考察两种昆虫食草动物对不同施肥制度下生长的两种植物的净影响。它是专门为了解受精和昆虫食草性对植物生产力的影响而设计的。研究对象是两个具有不同生活史特征的重要经济和生态树种(栎树和棉杨)和两个经济有害的食草性昆虫物种。施肥试验将在种植的田间地块和温室中进行，用于控制和比较目的。在昆虫食草动物存在和不存在的情况下，每个树种的样本将暴露在不同的施肥计划中，并将测量对植物生长、组织化学和食草动物性能的影响。这项研究的结果应该有助于更好地理解在有或没有昆虫食草动物的情况下，施肥水平和添加量对植物生产力的影响。它们将揭示何时在施肥对植物生长的积极影响和通过刺激昆虫取食植物而产生的负面影响之间进行权衡。长期的结果可能包括制定施肥措施，优化植物的净生产力，同时减少化肥和杀虫剂的需求。

9423316 Coleman Nitrogen fertilization is well known to both increase plant productivity and insect herbivore damage. Certain levels and rates of fertilization may negatively affect plant productivity by increasing the amount of damage by insects. This research will examine the net impact of two insect herbivores on two plant species grown under various fertilization regimes. It is designed specifically to understand the consequences of fertilization and insect herbivory in combination on plant productivity. Two economically and ecologically important tree species (oak and cottonwood) with contrasting life history traits and two economically detrimental insect herbivore species are the subjects. Fertilization experiments will be carried out in both a planted field plot and, for control and comparison purposes, in a greenhouse. Samples of each tree species will be exposed to differing fertilization schedules in the presence and absence of insect herbivores, and effects on plant growth, tissue chemistry, and herbivore performance will be measured. The results of this study should improve understanding of the impact on plant productivity of fertilization levels and rates of addition, in the presence and absence of insect herbivores. They will reveal when tradeoffs occur between positive effects of fertilization on plant growth and negative effects of fertilization through stimulation of insect feeding on plants. The long term result may include the formulation of fertilization practices that optimize net productivity of plants, yet reduce fertilizer and pesticide requirements.