Invasive lespedeza cuneata and its relationship to soil microbes and plant-soil feedback

Lespedeza cuneata;Soil;Microbes;Plant-soil feedback

Beck, Alyssa Marie

关键词: Lespedeza cuneata;    Soil;    Microbes;    Plant-soil feedback;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/98371/BECK-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Globalization has lead to increased frequencies of exotic plant invasions, which can reduce biodiversity and lead to extinction of native species. Physical traits that increase competitive ability and reproductive output encourage the invasiveness of exotic plants. Interactions with the soil microbial community can also increase invasiveness through plant-soil feedback, which occurs through shifts in the abundance of beneficial and deleterious organisms in soil that influence the growth of conspecific and heterospecific progeny. Lespedeza cuneata is an Asian legume that has become a problematic invader in grasslands throughout the United States. While L. cuneata has numerous traits that facilitate its success, it may also benefit from interactions with soil microbes. Previous studies have shown that L. cuneata can alter bacterial and fungal community composition, benefit more from preferential nitrogen-fixing symbionts than its native congener, L. virginica, and disrupt beneficial fungal communities associated with the native grass Panicum virgatum. L. cuneata litter and root exudates also have high condensed tannin contents, which may make them difficult to decompose and allow them to uniquely influence microbial communities in ways that benefit conspecific but not heterospecific plants. Plant-mediated shifts in the relative abundance of beneficial and deleterious microbes that influence future plant growth are known as plant-soil feedbacks. The objective of this dissertation is to examine plant-soil feedback in the L. cuneata system. In Chapter 2, I conduct a greenhouse experiment that identifies plant-soil feedbacks between L. cuneata and native potential competitors and use whole-community DNA sequencing to identify potential microbial drivers of observed feedbacks. Results showed that L. cuneata limits the growth of itself and native plants, but it benefits from microbes that were enriched in native-conditioned soil. This negative plant-soil feedback may facilitate early stages of L. cuneata invasion. In Chapter 3, I conduct a greenhouse experiment that examines the role that multiple plant chemical inputs may play in facilitating plant-soil feedback. Results suggest that in situ plant-soil feedback is mediated by complex sums of multiple plant inputs, but that root exudates may be especially important for structuring symbiont and pathogen populations. Metabolites from L. cuneata chemical inputs may also directly harm native plant growth. In Chapter 4, I conduct a follow up study to determine whether observations from my greenhouse study are applicable in the field. I found that L. cuneata invasion has lasting affects on soil microbial community composition in the field, which may be sufficient to drive plant-soil feedback in situ. Similar symbiont and decomposer OTUs were identified as being enriched by L. cuneata in both the greenhouse and the field. The results from this dissertation provide a novel examination of the influence of L. cuneata on plant-soil feedback patterns. As plant-soil feedbacks influence the outcome of plant competitive dynamics, they may have large implications for effects of exotic plants on invaded ecosystems.