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You searched for +publisher:"University of Arizona" +contributor:("Sheppard, Paul"). Showing records 1 – 3 of 3 total matches.

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University of Arizona

1. Shepard, Robert Michal. Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass .

Degree: 2015, University of Arizona

Velvet mesquite (Prosopis velutina Woot.) is a common tree in semi-arid, southwestern U.S. savanna ecosystems. While there are studies that examine some of the physiological and ecological aspects of this tree (response to fire, net ecosystem exchange, encroachment into grasslands, yearly growth through dendrometer bands, among others), the wood anatomical features of a growth ring, suitability for dendrochronological research, life history, and above-ground biomass through time are knowledge gaps that can be filled. The purpose of this study was to examine these gaps in order to better understand the role of velvet mesquite in these ecosystems. Wood anatomical analysis showed that velvet mesquite has a semi-ring porous structure and termination of the growth ring is indicated by a small band of parenchyma. Visual crossdating of velvet mesquite was successful but a complex growth habit, with both eccentric and lobate growth, combined with ecological pressures hampered statistical validation of the chronology. Seasonal climate-growth analysis of dated rings showed a strong positive correlation to previous year September and October precipitation and a strong positive partial correlation to previous year September and August mean temperature. Life history through growth curve analysis showed no age related growth trend (either s-shaped or log normal) indicating the maximum age of velvet mesquite stems sampled (130 years old) can become much older with many releases and few suppressions. Above-ground biomass of these trees are low compared to higher elevation forest biomass, but similar to other savanna ecosystems of the southwest. The use of velvet mesquite in dendrochronological research would greatly benefit from a complete analysis of wood anatomy, and addition of more samples from various locations to verify dates and begin building more reliable chronologies for this species across its range. These additions would allow for a greater understanding of stand and tree level responses through suppressions and releases, and understand the biomass accumulated above-ground through time. Advisors/Committee Members: Trouet, Valerie (advisor), Trouet, Valerie (committeemember), Archer, Steve (committeemember), Scott, Russ (committeemember), Sheppard, Paul (committeemember).

Subjects/Keywords: growth curves; Prosopis velutina; Tree rings; velvet mesquite; wood anatomy; Natural Resources; Dendrochronology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Shepard, R. M. (2015). Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass . (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/605122

Chicago Manual of Style (16th Edition):

Shepard, Robert Michal. “Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass .” 2015. Masters Thesis, University of Arizona. Accessed October 20, 2019. http://hdl.handle.net/10150/605122.

MLA Handbook (7th Edition):

Shepard, Robert Michal. “Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass .” 2015. Web. 20 Oct 2019.

Vancouver:

Shepard RM. Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass . [Internet] [Masters thesis]. University of Arizona; 2015. [cited 2019 Oct 20]. Available from: http://hdl.handle.net/10150/605122.

Council of Science Editors:

Shepard RM. Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass . [Masters Thesis]. University of Arizona; 2015. Available from: http://hdl.handle.net/10150/605122

2. Chiriboga, April Therese. Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring .

Degree: 2015, University of Arizona

The world's forests sequester roughly a quarter of anthropogenic emissions of carbon dioxide and store it in wood. Assessing this carbon sink includes quantifying annual wood production, establishing baselines, and characterizing both long-term trends and inter-annual variability. Direct measures of forest wood production are often based on measures of individual tree growth along the stem, often taken at a single height: basal height (1.3 meters). This assumes that a measurement of wood production at a single height is representative of wood production along the whole stem. In violation of this assumption, it is known that trees do accumulate wood differentially along the stem, and that this longitudinal variability can change from year to year. Few efforts have been made to describe annual longitudinal variability, and quantify the error in estimated annual whole-stem wood production related to assuming that constant wood production along the stem. In the present study, I present a stem analysis of 30 Populus grandidentata to address this. Dendrochronological techniques are used to develop three chronologies: a traditional tree-ring width chronology from basal height, a novel chronology developed from tree rings grown in the crown of the trees, and a specific volume increment chronology calculated from measured annual volume increment data. A novel taper chronology is also presented. In Chapter 2, comparisons are made between the chronologies to explore differences in inter-annual variability, and the suitability for using tree-ring data from basal height as a proxy for annual wood production. Both basal and crown tree-ring width chronologies were strongly correlated with the volume chronology (r = 0.96 and 0.88, respectively), suggesting that the basal chronology is a superior proxy for stem volume. However, a chronology of taper along the stem indicates that the reliability of either chronology to represent specific volume increment (SVI) changes over time, resulting in different common signals, especially in the last decade of this dataset. If accurately capturing the relative year-to-year changes in stem wood volume is desired, stem dissection and development of an SVI chronology is required. In Chapter 3, two models that use tree-ring data to estimate annual wood production are compared to volume measurements from the stem analysis. The two models are a site-specific allometric model of biomass, and a simplified conic model of volume. Additionally the conic model is decomposed into the three dimensions of growth along which variability exists (around the circumference, along the length of the stem, and height) to identify which dimension introduces the most error when no variability in that dimension is assumed. Relative error (RE) analysis and regression analysis show that stem analysis is superior in cases where few trees are used and accurate measures of wood increment are needed. At the population level, the allometric and conic models show different strengths. Allometric models are more accurate than the… Advisors/Committee Members: Sheppard, Paul R (advisor), Leavitt, Steven W (advisor), Sheppard, Paul R. (committeemember), Leavitt, Steven W. (committeemember), Falk, Donald A. (committeemember), Russell, Joellen L. (committeemember), Saleska, Scott R. (committeemember).

Subjects/Keywords: Tree physiology; Tree-rings; Geosciences; Carbon

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APA (6th Edition):

Chiriboga, A. T. (2015). Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/578835

Chicago Manual of Style (16th Edition):

Chiriboga, April Therese. “Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring .” 2015. Doctoral Dissertation, University of Arizona. Accessed October 20, 2019. http://hdl.handle.net/10150/578835.

MLA Handbook (7th Edition):

Chiriboga, April Therese. “Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring .” 2015. Web. 20 Oct 2019.

Vancouver:

Chiriboga AT. Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring . [Internet] [Doctoral dissertation]. University of Arizona; 2015. [cited 2019 Oct 20]. Available from: http://hdl.handle.net/10150/578835.

Council of Science Editors:

Chiriboga AT. Longitudinal Variation in Wood Accumulation along the Stem of Populus Grandidentata; Implications for Forest Carbon Monitoring . [Doctoral Dissertation]. University of Arizona; 2015. Available from: http://hdl.handle.net/10150/578835


University of Arizona

3. McCoy, Amy LaFerne. Riparian Dynamics: The Ebb and Flow of Ecological Function .

Degree: 2009, University of Arizona

Competition over freshwater resources is increasing at local and global scales. Growing urban and suburban centers utilize surface and groundwater resources to meet municipal, industrial, and agricultural demands, often at the expense of riparian ecosystems. Paradoxically, those same urban centers produce a significant volume of treated effluent that can be reused to restore and sustain riparian systems. Use of effluent as a source of water for the environment raises important questions about the benefits and impacts of effluent on riparian functions and ecosystem services, particularly in the context of climate change and drought conditions. This dissertation addresses knowledge gaps surrounding riparian change and resilience along the effluent-dominated Upper Santa Cruz River in southern Arizona. Appendix A investigates whether the Netleaf hackberry (Celtis laevigata var. reticulata) tree can provide accurate information on historic changes in climatic and hydrological conditions. Results indicate that hackberry trees do record climate-related stress in annual ring-width patterns and can therefore provide a historic frame of reference against which to compare current and future changes in riparian conditions. Appendix B documents spatial and temporal patterns of effluent uptake by Fremont cottonwood trees (Populus fremontii) through development of a new application for dendrochronology, specifically dendrochemistry. Results show that annual tree rings contain temporally variable concentrations of a micropollutant found only in effluent and may have the potential to record spatial and temporal patterns of effluent dispersion in riparian ecosystems. Appendix C investigates the complex interactions of ecohydrological conditions that led to a riparian mortality event along the Upper Santa Cruz River in 2005. Effluent is shown to contribute to riparian vegetation expansion, but also, due to its consistent delivery of nutrients and water, homogenize the system and ultimately diminish its resilience to perturbations and stress. Results highlight the paradoxical nature of effluent as both a contributor to riparian growth and a potential impediment to riparian function. This paradox can be resolved through a well-defined effluent impact monitoring and assessment program that incorporates historic information as well as current trends to detect significant changes in ecosystem functions and services. Advisors/Committee Members: Orr, Barron J (advisor), Marsh, Stuart E. (committeemember), Meko, David M. (committeemember), Sheppard, Paul R. (committeemember), van Leeuwen, Willem J.D. (committeemember).

Subjects/Keywords: Dendrochronology; Ecological monitoring; Ecosystem Services; Effluent; Gadolinium; Riparian Ecosystems

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

McCoy, A. L. (2009). Riparian Dynamics: The Ebb and Flow of Ecological Function . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/194012

Chicago Manual of Style (16th Edition):

McCoy, Amy LaFerne. “Riparian Dynamics: The Ebb and Flow of Ecological Function .” 2009. Doctoral Dissertation, University of Arizona. Accessed October 20, 2019. http://hdl.handle.net/10150/194012.

MLA Handbook (7th Edition):

McCoy, Amy LaFerne. “Riparian Dynamics: The Ebb and Flow of Ecological Function .” 2009. Web. 20 Oct 2019.

Vancouver:

McCoy AL. Riparian Dynamics: The Ebb and Flow of Ecological Function . [Internet] [Doctoral dissertation]. University of Arizona; 2009. [cited 2019 Oct 20]. Available from: http://hdl.handle.net/10150/194012.

Council of Science Editors:

McCoy AL. Riparian Dynamics: The Ebb and Flow of Ecological Function . [Doctoral Dissertation]. University of Arizona; 2009. Available from: http://hdl.handle.net/10150/194012

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