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Effects of global change on savanna grassland ecosystems

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/21049

Effects of global change on savanna grassland ecosystems

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dc.contributor.author Koerner, Sally
dc.date.accessioned 2012-08-28T16:30:14Z
dc.date.available 2012-08-28T16:30:14Z
dc.date.issued 2012-08-28
dc.date.submitted July 2012
dc.identifier.uri http://hdl.handle.net/1928/21049
dc.description.abstract Humans are altering the environment locally and globally through climate and land use change. Global temperature is increasing, precipitation patterns are becoming more variable, disturbance regimes are being altered, and ecosystems are being simplified as multi-species communities are replaced by monocultures of crops or livestock. Grasslands, which cover approximately a third of the terrestrial lands, are ecologically and economically significant, thus their responses to environmental change will have dramatic consequences for global patterns of productivity, biodiversity, and food production. This dissertation research investigates how the three main drivers of mesic grassland ecosystems – precipitation, grazing, and fire - interact to affect community composition, structure, and dynamics. I utilized an existing cross-continental study to determine the degree to which mechanisms controlling diversity and dynamics in North American (NA) savanna grasslands apply to Southern African (SA) systems, and vice versa. I conducted my research in two savanna grassland ecosystems: Kruger National Park (Kruger), in northeastern South Africa, and Konza Prairie Biological Station (Konza), in northeastern Kansas, USA. Overall, this dissertation shows that on small scales different grasslands exhibit similar responses to grazing and fire, and to grazing, fire, and drought. However, the generality seen in small-scale responses may not transfer to larger landscape scale processes because patch dynamics within these landscapes are strongly affected by grazing and fire in NA but not in SA. This research also showed that grazing more frequently affected community properties like diversity, cover, and ANPP, while both drought and changes in rainfall variability rarely affected those properties. Instead grasslands responded to changes in rainfall by altering stem densities, and only then in the presence of grazing. As the majority of grasslands globally are grazed, current climate change experiments in grasslands may be underestimating the effects of altered precipitation patterns on the population dynamics of species within these ecosystems. en_US
dc.description.sponsorship The National Science Foundation, The United States Department of Agriculture, The University of New Mexico Biology Department, The University of New Mexico Office of Graduate Studies en_US
dc.language.iso en_US en_US
dc.subject grasslands en_US
dc.subject grazing en_US
dc.subject fire en_US
dc.subject precipitation en_US
dc.subject global change en_US
dc.subject plant community composition en_US
dc.subject Konza Prairie en_US
dc.subject Kruger National Park en_US
dc.subject South Africa en_US
dc.subject Kansas en_US
dc.subject patch en_US
dc.subject rainout shelter en_US
dc.subject drought en_US
dc.subject.lcsh Grassland ecology--Kansas--Konza Prairie Research Natural Area.
dc.subject.lcsh Grassland ecology--South Africa--Kruger National Park.
dc.subject.lcsh Climatic changes ǂx Environmental aspects.
dc.title Effects of global change on savanna grassland ecosystems en_US
dc.type Dissertation en_US
dc.description.degree Biology en_US
dc.description.level Doctoral en_US
dc.description.department University of New Mexico. Biology Dept. en_US
dc.description.advisor Collins, Scott
dc.description.committee-member Dahm, Clifford
dc.description.committee-member Litvak, Marcy
dc.description.committee-member Knapp, Alan


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