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Colorado State University (2021)

Soil nematode community response to climate change and associated alterations to precipitation and vegetation

Ankrom, Katharine Elizabeth

Titre : Soil nematode community response to climate change and associated alterations to precipitation and vegetation

Auteur : Ankrom, Katharine Elizabeth

Université de soutenance : Colorado State University

Grade : Doctor of Philosophy (PhD) 2021

Résumé partiel
Understanding of the belowground grassland response to climate change is much more limited than aboveground responses. This disparity in knowledge is partially due to the vast diversity in species in belowground ecosystems and the overwhelming task of identifying the roles and processes associated with each. Soil nematodes represent the most abundant soil fauna on earth and are exceptional in that they occupy every trophic level, contain multiple life history strategies, and are relatively easy to extract and identify from soil. Moreover, nematode activity (e.g. feeding) directly regulates the size and function of fungal and bacterial populations thus indirectly impacting the rates of carbon and nitrogen turnover. Determining the abundance of each nematode genera in a soil sample can allow for calculation of ecological indices that can further explore the trophic complexity, energy pathways, and both the sensitivity and resilience of soil nematode communities to stress and disturbance. Therefore studying soil nematode communities provides a means for gaining important insights about poorly understood belowground responses to altered environments. The aim of this dissertation is to expand our knowledge of soil community dynamics in grasslands in the face of extreme precipitation changes and possible vegetation shifts. In the first chapter of this dissertation, I introduce the importance of grassland ecosystems and the challenges looming from climate change. Next I highlight the two scenarios in which my research is based and give the details on how utilizing nematode data can answer these questions. The second chapter of this dissertation addresses the question : Can nematode trophic analysis reveal associations between vegetation cover types ? This study revealed striking differences in the abundances of fungivores and the combined omnivore/predator trophic groups found under the dominant grass compared to both an invasive forb and bare soil cover types. In the third chapter a focus on the most well-studied nematode trophic group ; plant parasitic nematodes (PPN) sought to determine if different feeding strategies lead to distinct responses in precipitation treatments across three grassland sites.

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