Carbon Sequestration and Agents of Woody Encroachment in Southeastern Arizona Semi-arid Grasslands

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dc.contributor.advisorJustice, Christopheren_US
dc.contributor.authorO'Neal, Kelleyen_US
dc.contributor.departmentGeographyen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2014-10-11T05:59:03Z
dc.date.available2014-10-11T05:59:03Z
dc.date.issued2014en_US
dc.description.abstractWoody encroachment and proliferation within dryland ecosystems is potentially the second largest portion of the North American carbon sink and one of the largest areas of uncertainty. This dissertation examines a semi-arid grassland located in southeastern Arizona to better understand woody encroachment, agents of change, and the resultant carbon storage from 1984-2008. The objectives were to quantify changes in woody cover, rank agent importance, estimate carbon density, and calculate voluntary market value. The first objective of mapping changes in woody cover was addressed using a Landsat time-series to measure woody cover and calculate the change, rate of change, and change relative to initial cover over the 25-year time period. Results show the change in woody cover varies spatially and ranges from approximately -2 to 11% with most areas experiencing a 5% increase and 92% relative increase over initial cover, indicating woody cover nearly doubled in the region. The second objective of ranking the importance of agents was achieved using an ensemble classifier. Agents examined included grazing, number of times burned, soil texture, soil productivity, elevation, slope, aspect, and initial woody cover. Initial woody cover, number of times burned, elevation, and grazing were ranked as the most important agents of woody encroachment, indicating the importance of historical land management and disturbance, frequent fire, topography and correlated precipitation, and land use. The third objective of producing carbon estimates and calculating economic opportunity in the voluntary carbon markets was accomplished by applying cover to biomass, root:shoot, and carbon equations to the final woody plant cover maps to calculate carbon stocks, carbon density, and voluntary market value. Results show very low carbon density in the study area relative to similar ecosystems and other ecosystems in general. Given the insignificant annual accumulation of carbon on the small ownership parcels, current low carbon trading prices, and high beef prices, management for storage is not economically viable in the study area at this time.en_US
dc.identifierhttps://doi.org/10.13016/M2V59J
dc.identifier.urihttp://hdl.handle.net/1903/15827
dc.language.isoenen_US
dc.subject.pqcontrolledGeographyen_US
dc.subject.pqcontrolledRange managementen_US
dc.subject.pqcontrolledEcologyen_US
dc.subject.pquncontrolledArizonaen_US
dc.subject.pquncontrolledCarbonen_US
dc.subject.pquncontrolledFireen_US
dc.subject.pquncontrolledGrasslanden_US
dc.subject.pquncontrolledGrazingen_US
dc.subject.pquncontrolledWoody Encroachmenten_US
dc.titleCarbon Sequestration and Agents of Woody Encroachment in Southeastern Arizona Semi-arid Grasslandsen_US
dc.typeDissertationen_US

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