Dissertation Research: The Effects of Light and Arbuscular Mycorrhizae on Oak Savanna Plant Community Composition

丛枝菌根真菌(AMF)是植物根部最常见的有益真菌。这项研究验证了这样一种假设，即光可获得性和AMF相互作用，影响中西部橡树稀树草原上极其多样化的植物群落的组成。阳光充足地区的植物对土壤养分的需求更大，因此与阴凉地区的植物相比，AMF(或从高度活跃的AMF物种)中可能受益更多。阴凉处的植物要么缺乏AMF，要么与代谢率较低的物种有关。因此，真菌物种的种类和数量沿日照到阴凉梯度的变化可能会对稀树草原植物的特性和多样性产生深远的影响。为了验证这些想法，我们将首先测量植物物种和AMF物种的分布，作为光可获得性和土壤质地的函数在威斯康星州的三个稀树草原。AMF对林下植物的影响将通过对试验田使用杀菌剂并记录相对于未处理地在两年时间内植物成分的变化来评估。最后，我们将在温室条件下进行实验，以确定不同的AMF物种在单独生长时对单个植物物种生长的影响，以及在一起生长时对这些相同物种的竞争能力的影响。

Arbuscular mycorrhizal fungi (AMF) are the most common kind of beneficial fungi associated with plant roots. This study tests the hypothesis that light availability and AMF interact to influence the composition of the remarkably diverse plant communities in Midwestern oak savannas. Plants in sunnier areas have greater needs for soil nutrients, and so may benefit more from AMF (or from highly active AMF species) than plants in shady sites. Plants in shady sites should either lack AMF or be associated with species having lower metabolic rates. Shifts in the kinds and numbers of fungal species along sun-to-shade gradients may thus have a profound effect on the identity and diversity of savanna plants. To test these ideas, we will first measure the distributions of plant species and AMF species as a function of light availability and soil texture in three Wisconsin savannas. The effects of AMF on understory plants will then be evaluated by applying fungicide to experimental field plots and documenting changes in plant composition over a two-year period relative to untreated plots. Finally, we will conduct experiments under greenhouse conditions to determine the effects of different AMF species on the growth of individual plant species when they are grown alone, and on the competitive ability of those same species when grown together.