Coupling Rhizosphere Biogeochemical Cycles to Plant Growth under Differing Levels of Carbon Dioxide

土壤食物网是多种物种的复杂组合，将土壤中的矿质养分循环与根区生态系统（根际圈）中植物的初级生产力相结合。这些相互作用将植物根部渗出的碳与各种捕食者-猎物关系联系起来，这些关系通过矿化将多余的氮返还给生长中的植物。先前的研究表明，在根际食物网中存在捕食者可以使植物生长增加50%到150%。该项目将使用质量同位素和分子遗传学技术来确定调节这些相互作用所涉及的过程。工作将以一个分层数学模型为指导，该模型旨在预测大气二氧化碳和温度的增加如何影响根际碳储存。土壤中碳和氮循环之间的联系将通过在不同水平的大气二氧化碳和温度下的实验来澄清，从而使生态系统达到新的平衡。这个项目的一个重要之处在于它对大气中二氧化碳含量增加所产生的额外碳是否可以储存在土壤中的争论做出了贡献。这项工作的其他方面将确定促进植物生长的机制，同时维持细菌、线虫和以线虫为食的螨虫之间有益的相互作用。

Soil food webs are complex assemblages of diverse species that couple mineral nutrient cycles in the soil to primary productivity of plants in root-zone ecosystems known as rhizospheres. These interactions link carbon from plant root exudates to a variety of predator-prey relationships that return excess nitrogen through mineralization to the growing plant. Previous work shows that the presence of predators in the rhizosphere food web can increase plant growth 50 to 150%. This project will use mass-isotope and molecular genetic techniques to identify processes involved in regulating these interactions. Work will be guided by a hierarchical mathematical model designed to predict how increases in atmospheric carbon dioxide and temperature influence carbon storage in the rhizosphere. Linkages between the carbon and nitrogen cycles in soil will be clarified by experiments under different levels of atmospheric carbon dioxide and temperature that move the ecosystem to new equilibria. One importance of this project lies in its contribution to the debate over whether additional carbon from increasing levels of atmospheric carbon dioxide can be stored in soil. Other aspects of the work will identify mechanisms that promote plant growth while sustaining beneficial interactions among bacteria, nematodes and mites that prey on nematodes.