EXPERIMENTAL AND ANALYTICAL APPROACH TO INVESTIGATING PLANT-SOIL FEEDBACK

Junhwi Yoo

Date of Award

2017

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Oberle, Brad

Area of Concentration

Biology

Abstract

Biodiversity, and subsequently its productivity, is an important cultural, educational and economic asset. Since its proposal in 1970, the Janzen-Connell hypothesis has long been studied as a potential explanation for the presence of tree biodiversity in tropical habitats. The hypothesis maintains that accumulation of species-specific natural enemies around an adult tree prevent the success of conspecific seedlings. More recently, research has pointed to soil microbes as the main drivers of this mechanism. This project is a culmination of two different approaches to studying this phenomenon. The first is an experimental approach to assess the direct effect of soil microbes on seed germination as well as the indirect effects on viability of seeds produced by the parent plants engaged in these interactions. The second is an analytical approach that uses data collected over multiple contemporary studies to determine the presence of phylogenetic signal in plant-soil feedback. The first study found that seed viability and germination rate and their response to different soil microbe treatments depended heavily on the species of plants with few species showing significant effects. The second study found no phylogenetic signal when correlating plant duration and plant-soil feedback values. Overall, the study shows that soil microbe-interactions and their effects vary more widely than previously thought. Further research should continue to investigate the extent of these variations as well as their potential causes.

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