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dc.contributor.advisorSmith, Melinda D.
dc.contributor.authorGray, Jesse E.
dc.contributor.committeememberKnapp, Alan K.
dc.contributor.committeememberOcheltree, Troy W.
dc.date.accessioned2017-06-09T15:42:54Z
dc.date.available2017-06-09T15:42:54Z
dc.date.issued2017
dc.description2017 Spring.
dc.descriptionIncludes bibliographical references.
dc.description.abstractTwo grass species, Andropogon gerardii and Sorghastrum nutans, together account for the great majority of individuals, biomass, and possibly genetic diversity in plant communities of the tallgrass prairies of the Great Plains, US. As competitors with similar functional traits and what appears to be overlapping niches, it is not clear what mechanisms facilitate their co-dominance, but it may rely on the high variability of environmental conditions that characterize grassland ecosystems. Because these abundant grasses strongly influence plant community structure and ecosystem function, it is critical that we understand the factors influencing the population dynamics of these species, and how climate change might alter those relationships. We found an asynchrony in population dynamics in which A. gerardii begins each growing season at higher tiller densities, with attrition of tillers starting mid-season. Concurrent gains of S. nutans tillers results in A. gerardii becoming the less abundant by the end of most growing seasons. We hypothesized that this differentiation in tillering strategies causes each species to be vulnerable to unfavorable environmental conditions during different parts of the growing season, thus enabling their coexistence by preventing an inter-annually consistent competitive advantage of either species. We found that greater tiller density asynchrony was associated with higher population densities of S. nutans and of aggregate tiller densities of both species. Experimental increases in temperature and rainfall variability reduced population-level asynchrony while exacerbating population declines and overall community productivity, suggesting this mechanism of co-dominance may rely on current levels of environmental variability, and may be vulnerable to projected increases in that variability with climate change.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierGray_colostate_0053N_14162.pdf
dc.identifier.urihttp://hdl.handle.net/10217/181431
dc.languageEnglish
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019 - CSU Theses and Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectcoexistence
dc.subjectdominant species
dc.subjectresponse asynchrony
dc.subjectcompetition
dc.subjectcodominance
dc.subjectpopulation dynamics
dc.titleClimate change impacts on population dynamics in tallgrass prairie: implications for species codominance
dc.typeText
dcterms.rights.dplaThe copyright and related rights status of this item has not been evaluated (https://rightsstatements.org/vocab/CNE/1.0/). Please refer to the organization that has made the Item available for more information.
thesis.degree.disciplineEcology
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)


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