Dissertation Research: Nitrogen and Water Utilization by Co-occurring Evergreen Oak that Differ in Rooting Depth

将调查生长在蛇纹石衍生土壤上的两种橡树对水和氮素的吸收和利用模式。初步结果表明，黑皮栎和杜拉特栎根深不同，土壤水分和氮素有效性随深度和季节的不同而不同。假设由于土壤资源有效性和根系分布之间的空间交互作用，邻近的杜鹃和黑栎个体可以获得不同水平的氮素和水分。进一步预测，这两个物种的相邻个体对氮和水的获取和利用应该是不同的。这些假设将使用现场和受控环境研究进行调查。关于生根深度的信息将与几个深度的水和氮的可用性进行比较。将遵循几组相邻大小匹配的植物对氮和水的吸收和利用的季节性模式，并将通过在营养砂培条件下生长的植物来调查杜拉塔栎和黑荆对氮和水有效性的适应方式，该条件旨在模拟可用于浅根和深根植物的资源。

The patterns of water and nitrogen acquisition and utilization by two species of oaks growing on serpentine-derived soil will be investigated. Preliminary results indicate that Quercus agrifolia and Q. durata differ in rooting depth, and that the availability of water and nitrogen in the soil varies with both depth and season. It is hypothesized that, as a result of spatial interactions between soil resource availability and root distribution, neighboring individuals of Q. durata and Q. agrifolia have access to different levels of nitrogen and water. It is further predicted that neighboring individuals of the two species should differ in the acquisition and utilization of nitrogen and water. These hypotheses will be investigated using both field and controlled environment studies. Information on rooting depth will be compared with the availability of water and nitrogen at several depths. The seasonal patterns of nitrogen and water acquisition and utilization for several sets of adjacent size matched plants will be followed, and the ways in which Q. durata and Q. agrifolia acclimate to nitrogen and water availability will be investigated by growing plants under nutrient sand-culture conditions designed to simulate the resources available to shallowly and deeply rooted plants.