EROC: Comparative Effects of Elevated Atmospheric Carbon Dioxide Within Two Multiple Trophic Level Systems

。9509089卡洛威当植物生长在二氧化碳浓度升高的环境中时，它们的叶子通常含有较少的氮，但可能含有更多、更少或相同数量的防御化学物质。这项研究提出了两个主要问题：！)二氧化碳诱导的植物质量变化是否影响更高的营养级(例如，捕食植物的毛虫、在毛虫体内发育并捕食毛虫的寄生蜂、在体内发育并捕食寄生蜂的重寄生蜂)，以及2)寄主植物与固氮菌的联系是否缓冲了所有营养级，使其免受二氧化碳升高的直接影响？为了回答这些问题，我们将比较以十字花科(非固氮)寄主植物和豆科(固氮)寄主植物为基础的四个营养水平系统中，二氧化碳浓度升高对植物营养品质和防御化学的影响，以及随后对食草动物、寄生蜂和重寄生蜂的影响。这项研究将扩大我们对二氧化碳升高的生态后果的理解，包括第三和第四营养级别，并开始评估不同营养级别系统对二氧化碳升高直接影响的敏感性差异的机制。由于我们重要的经济作物包括豆类和非豆类，并支持多种营养水平，这些信息可能会在未来，即二氧化碳浓度升高的情况下提高农业生产率。

. 9509089 Karowe When plants are grown under elevated carbon dioxide, their leaves usually contain less nitrogen but may contain more, less, or the same amount of defensive chemicals. This research asks two main questions: !) Do CO2-induced changes in plant quality affect higher trophic levels (e. g. caterpillars that consume plants, parasitoid wasps that develop inside and consume caterpillars, and hyperparasitoid wasps that develop inside and consume parasitoid wasps), and 2) Does association of host plants with nitrogen-fixing bacteria buffer all trophic levels against the direct effects of elevated CO2? To answer these questions, the effects of elevated CO2 on plant nutritional quality and defensive chemistry, and subsequent effects on herbivores, parasitoids, and hyperparasitoids will be compared between a four trophic level system based on crucifer (non-nitrogen fixing) host plants and one based on legume (nitrogen fixing) host plants. This research will expand our understanding of the ecological consequences of elevated CO2 to include the third and fourth trophic levels, and to begin to assess the mechanisms responsible for variability among different multiple trophic level systems in their susceptibility to the direct effects of elevated CO2. Because our economically important agricultural crops include both legumes and non-legumes, and support multiple trophic levels, this information may enhance agricultural productivity under the future, i. e., elevated CO2 atmosphere.