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dc.contributor.advisorHuxman, Travis E.en_US
dc.contributor.advisorBreshears, David D.en_US
dc.contributor.authorAdams, Henry*
dc.creatorAdams, Henryen_US
dc.date.accessioned2012-06-11T22:31:56Z
dc.date.available2012-06-11T22:31:56Z
dc.date.issued2012
dc.identifier.urihttp://hdl.handle.net/10150/228494
dc.description.abstractDrought-induced tree mortality is an emerging global phenomenon that appears related to climate change and rising temperatures in particular, and may be an early indication of vegetation change. However, vegetation response to climate change is uncertain, particularly for future novel climates. Notably, no current models of vegetation change attempt to mechanistically predict plant mortality, and in particular, mortality of trees, which exerts strong influences on ecological function. Resolving uncertainties surrounding the physiological mechanism and temperatures sensitivity of tree mortality is a current challenge in global change ecology. The objectives of this dissertation were to 1) consider tree mortality consequences for earth system processes related to carbon, water, and energy exchange that include climate regulation; 2) explore tree mortality effects on the water cycle by developing hypotheses and research needs; 3) quantify the temperature sensitivity of drought-induced tree mortality and gain insight into the physiological mechanism of mortality; 4) quantify the relationships among temperature, stored carbohydrate resources, and gas exchange to further elucidate physiological tree mortality mechanisms; and 5) quantify the sensitivity of two species of pine seedlings to progressively elevated temperatures and relate mortality to the effect of temperature on carbon metabolism. Major findings of this dissertation relate to the temperature sensitivity, physiological mechanism, and implications of tree mortality. Assessment of the potential consequences of tree mortality for earth system processes documented the contrasting influences of tree mortality on the terrestrial C cycle and land-surface energy exchange, the balance of which will determine the net effects on climate regulation (Appendix A). Following a survey of the ecohydrology literature, thresholds for tree mortality to cause watershed changes were hypothesized at ~20% loss of canopy cover, ~500 mm of annual precipitation, and whether flows are snowmelt dominated (Appendix B). Elevated temperature (~+4°C) accelerated tree mortality by 28% during experimental drought, a difference related to cumulative respiration dynamics in piñon pine (Appendix C). Stored carbohydrate resources were declined during lethal drought but were not entirely depleted prior to mortality (Appendix D). Seedlings exhibited progressive declines in time-to mortality with increased temperatures, a response related to C metabolism (Appendix E).
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectecohydrologyen_US
dc.subjectglobal changeen_US
dc.subjecthydraulic failureen_US
dc.subjecttree mortalityen_US
dc.subjectEcology & Evolutionary Biologyen_US
dc.subjectcarbon starvationen_US
dc.subjectdroughten_US
dc.titleTemperature Sensitivity, Physiological Mechanism, and Implications of Drought-Induced Tree Mortalityen_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberSaleska, Scott R.en_US
dc.contributor.committeememberZou, Chris B.en_US
dc.contributor.committeememberSwetnam, Thomas W.en_US
dc.contributor.committeememberHuxman, Travis E.en_US
dc.contributor.committeememberBreshears, David D.en_US
dc.description.releaseRelease after 24-Oct-2012en_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEcology & Evolutionary Biologyen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2012-10-24T00:00:00Z
html.description.abstractDrought-induced tree mortality is an emerging global phenomenon that appears related to climate change and rising temperatures in particular, and may be an early indication of vegetation change. However, vegetation response to climate change is uncertain, particularly for future novel climates. Notably, no current models of vegetation change attempt to mechanistically predict plant mortality, and in particular, mortality of trees, which exerts strong influences on ecological function. Resolving uncertainties surrounding the physiological mechanism and temperatures sensitivity of tree mortality is a current challenge in global change ecology. The objectives of this dissertation were to 1) consider tree mortality consequences for earth system processes related to carbon, water, and energy exchange that include climate regulation; 2) explore tree mortality effects on the water cycle by developing hypotheses and research needs; 3) quantify the temperature sensitivity of drought-induced tree mortality and gain insight into the physiological mechanism of mortality; 4) quantify the relationships among temperature, stored carbohydrate resources, and gas exchange to further elucidate physiological tree mortality mechanisms; and 5) quantify the sensitivity of two species of pine seedlings to progressively elevated temperatures and relate mortality to the effect of temperature on carbon metabolism. Major findings of this dissertation relate to the temperature sensitivity, physiological mechanism, and implications of tree mortality. Assessment of the potential consequences of tree mortality for earth system processes documented the contrasting influences of tree mortality on the terrestrial C cycle and land-surface energy exchange, the balance of which will determine the net effects on climate regulation (Appendix A). Following a survey of the ecohydrology literature, thresholds for tree mortality to cause watershed changes were hypothesized at ~20% loss of canopy cover, ~500 mm of annual precipitation, and whether flows are snowmelt dominated (Appendix B). Elevated temperature (~+4°C) accelerated tree mortality by 28% during experimental drought, a difference related to cumulative respiration dynamics in piñon pine (Appendix C). Stored carbohydrate resources were declined during lethal drought but were not entirely depleted prior to mortality (Appendix D). Seedlings exhibited progressive declines in time-to mortality with increased temperatures, a response related to C metabolism (Appendix E).


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