Degree Name

Master of Science (MS)

Semester of Degree Completion

2019

Thesis Director

Scott J. Meiners

Thesis Committee Member

Thomas Canam

Thesis Committee Member

Yordan S. Yordanov

Abstract

Soil microbes have profound impacts on plant growth and survival and can either promote or inhibit plant dominance. Exotic plants are often strongly invasive because they have escaped their natural enemies, potentially including antagonistic soil microbes. I examined how the invasive shrub Lonicera maackii and a common native tree, Acer negundo, responded to soil microbial communities to determine the role of soil microbes in regulating invasion success. This was done by growing both species with microbes from invaded (L. maackii) and uninvaded (A. negundo) soils collected from three locations within a riparian forest. Seedlings were grown both in isolation (Experiment 1) and in combination (Experiment 2) with both live and sterilized soil inocula from these locations. Despite the expectation of minimal microbial inhibition due to a lack of natural enemies, L. maackii was strongly inhibited by 1/3 A. negundo and 3/3 L. maackii soil microbiome collections when grown in isolation. The native Acer negundo was strongly inhibited by 2/3 A. negundo and 3/3 L. maackii microbiome collections. Conversely, when grown together the soil microbiome largely mitigated negative interspecific interactions (i.e. plant-plant, plant-microbe) leading to a net advantage for L. maackii in many cases. This dynamic is likely key to L. maackii seedling success when it occurs with seedlings of other species, allowing L. maackii a competitive advantage through biotic interactions.

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