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ABSTRACT The Phoenix Four Rivers Flora is an inventory of all the vascular plants growing along the Salt, Gila, New and Agua Fria Rivers, and their tributaries in the Phoenix Metropolitan Area during the years of the study (2009-2011). This floristic inventory documents the plant species and habitats that exist currently in the project area, which has changed dramatically from previous times. The data gathered by the flora project thus not only documents how the current flora has been altered by urbanization, but also will provide a baseline for future ecological studies. The Phoenix Metropolitan Area is a large urbanized region in the Sonoran Desert of Central Arizona, and its rivers are important for the region for many uses including flood control, waste water management, recreation, and gravel mining. The flora of the rivers and tributaries within the project area is extremely diverse; the heterogeneity of the systems being caused by urbanization, stream modification for flood control, gravel mining, and escaped exotic species. Hydrological changes include increased runoff in some areas because of impermeable surfaces (e.g. paved streets) and decreased runoff in other areas due to flood retention basins. The landscaping trade has introduced exotic plant species that have escaped into urban washes and riparian areas. Many of these have established with native species to form novel plant associations.
ContributorsJenke, Darin (Author) / Landrum, Leslie R. (Committee member) / Pigg, Kathleen B. (Committee member) / Makings, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2011
Description
Often, when thinking of cities we envision designed landscapes, where people regulate everything from water to weeds, ultimately resulting in an ecosystem decoupled from biophysical processes. It is unclear, however, what happens when the people regulating these extensively managed landscapes come under stress, whether from unexpected economic fluctuations or from changing climate norms. The overarching question of my dissertation research was: How does urban vegetation change in response to human behavior? To answer this question, I conducted multiscale research in an arid urban ecosystem as well as in a virtual desert city. I used a combination of long-term data and agent-based modeling to examine changes in vegetation across a range of measures influenced by biophysical, climate, institutional, and socioeconomic drivers. At the regional scale, total plant species diversity increased from 2000 to 2010, while species composition became increasingly homogeneous in urban and agricultural areas. At the residential scale, I investigated the effects of biophysical and socioeconomic drivers – the Great Recession of 2007-2010 in particular – on changing residential yard vegetation in Phoenix, AZ. Socioeconomic drivers affected plant composition and increasing richness, but the housing boom from 2000 through 2005 had a stronger influence on vegetation change than the subsequent recession. Surprisingly, annual plant species remained coupled to winter precipitation despite my expectation that their dynamics might be driven by socioeconomic fluctuations. In a modeling experiment, I examined the relative strength of psychological, social, and governance influences on large-scale urban land cover in a desert city. Model results suggested that social norms may be strong enough to lead to large-scale conversion to low water use residential landscaping, and governance may be unnecessary to catalyze residential landscape conversion under the pressure of extreme drought conditions. Overall, my dissertation research showed that urban vegetation is dynamic, even under the presumably stabilizing influence of human management activities. Increasing climate pressure, unexpected socioeconomic disturbances, growing urban populations, and shifting policies all contribute to urban vegetation dynamics. Incorporating these findings into planning policies will contribute to the sustainable management of urban ecosystems.
ContributorsRipplinger, Julie (Author) / Franklin, Janet (Thesis advisor) / Collins, Scott L. (Thesis advisor) / Anderies, John M (Committee member) / Childers, Daniel L. (Committee member) / York, Abigail (Committee member) / Arizona State University (Publisher)
Created2015
Description
A floristic analysis is essential to understanding the current diversity and structure
of community associations of plants in a region. Also, a region’s floristic analysis is key not only to investigating their geographical origin(s) but is necessary to their management and protection as a reservoir of greater biodiversity. With an area of 2,250,000 square kilometers, the country of Saudi Arabia covers almost four-fifths of the Arabian Peninsula. Efforts to document information on the flora of Saudi Arabia began in the 1700s and have resulted in several comprehensive publications over the last 25 years. There is no doubt that these studies have helped both the community of scientific researchers as well as the public to gain knowledge about the number of species, types of plants, and their distribution in Saudi Arabia. However, there has been no effort to use digital technology to make the data contained in various Saudi herbarium collections easily accessible online for research and teaching purposes. This research project aims to develop a “virtual flora” portal for the vascular plants of Saudi Arabia. Based on SEINet and the Symbiota software used to power it, a preliminary website portal was established to begin an effort to make information of Saudi Arabia’s flora available on the world- wide web. Data comprising a total of 12,834 specimens representing 175 families were acquired from different organizations and used to create a database for the designed website. After analyzing the data, the Fabaceae family (“legumes”) was identified as a largest family and chosen for further analysis. This study contributes to help scientific researchers, government workers and the general public to have easy, unlimited access to the plant information for a variety of purposes.
of community associations of plants in a region. Also, a region’s floristic analysis is key not only to investigating their geographical origin(s) but is necessary to their management and protection as a reservoir of greater biodiversity. With an area of 2,250,000 square kilometers, the country of Saudi Arabia covers almost four-fifths of the Arabian Peninsula. Efforts to document information on the flora of Saudi Arabia began in the 1700s and have resulted in several comprehensive publications over the last 25 years. There is no doubt that these studies have helped both the community of scientific researchers as well as the public to gain knowledge about the number of species, types of plants, and their distribution in Saudi Arabia. However, there has been no effort to use digital technology to make the data contained in various Saudi herbarium collections easily accessible online for research and teaching purposes. This research project aims to develop a “virtual flora” portal for the vascular plants of Saudi Arabia. Based on SEINet and the Symbiota software used to power it, a preliminary website portal was established to begin an effort to make information of Saudi Arabia’s flora available on the world- wide web. Data comprising a total of 12,834 specimens representing 175 families were acquired from different organizations and used to create a database for the designed website. After analyzing the data, the Fabaceae family (“legumes”) was identified as a largest family and chosen for further analysis. This study contributes to help scientific researchers, government workers and the general public to have easy, unlimited access to the plant information for a variety of purposes.
ContributorsAlbediwi, Albatool (Author) / Wojciechowski, Martin (Thesis advisor) / Franz, Nico (Committee member) / Makings, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2017
Description
Baseline community composition data provides a snapshot in time that allows changes in composition to be monitored more effectively and can inform best practices. This study examines Arizona Upland plant community composition of the Sonoran Desert through three different lenses: floristic inventory, and fire and reseeding effects.
A floristic inventory was conducted at Cave Creek Regional Park (CCRP), Maricopa County, AZ. One hundred fifty-four taxa were documented within Park boundaries, including 148 species and six infraspecific taxa in 43 families. Asteraceae, Boraginaceae, and Fabaceae accounted for 40% of documented species and annuals accounted for 56% of documented diversity.
Fire effects were studied at three locations within McDowell Sonoran Preserve (MSP), Scottsdale, AZ. These fires occurred throughout the 1990s and recovered naturally. Fire and reseeding effects were studied at the site of a 2005 fire within CCRP that was reseeded immediately following the fire.
Two questions underlie the study regarding fire and reseeding effects: 1) How did fire and reseeding affect the cover and diversity of the plant communities? 2) Is there a difference in distribution of cover between treatments for individual species or growth habits? To address these questions, I compared burned and adjacent unburned treatments at each site, with an additional reseeded treatment added at CCRP.
MSP sites revealed overall diversity and cover was similar between treatments, but succulent cover was significantly reduced, and subshrub cover was significantly greater in the burn treatment. Seventeen species showed significant difference in distribution of cover between treatments.
The CCRP reseeded site revealed 11 of 28 species used in the seed mix persist 12 years post-fire. The reseeded treatment showed greater overall diversity than burned and unburned treatments. Succulent and shrub cover were significantly reduced by fire while subshrub cover was significantly greater in the reseeded treatment. Sixteen species showed significant difference in distribution of cover between treatments.
Fire appears to impact plant community composition across Arizona Upland sites. Choosing species to include in seed mixes for post-fire reseeding, based on knowledge of pre-fire species composition and individual species’ fire responses, may be a useful tool to promote post-fire plant community recovery.
A floristic inventory was conducted at Cave Creek Regional Park (CCRP), Maricopa County, AZ. One hundred fifty-four taxa were documented within Park boundaries, including 148 species and six infraspecific taxa in 43 families. Asteraceae, Boraginaceae, and Fabaceae accounted for 40% of documented species and annuals accounted for 56% of documented diversity.
Fire effects were studied at three locations within McDowell Sonoran Preserve (MSP), Scottsdale, AZ. These fires occurred throughout the 1990s and recovered naturally. Fire and reseeding effects were studied at the site of a 2005 fire within CCRP that was reseeded immediately following the fire.
Two questions underlie the study regarding fire and reseeding effects: 1) How did fire and reseeding affect the cover and diversity of the plant communities? 2) Is there a difference in distribution of cover between treatments for individual species or growth habits? To address these questions, I compared burned and adjacent unburned treatments at each site, with an additional reseeded treatment added at CCRP.
MSP sites revealed overall diversity and cover was similar between treatments, but succulent cover was significantly reduced, and subshrub cover was significantly greater in the burn treatment. Seventeen species showed significant difference in distribution of cover between treatments.
The CCRP reseeded site revealed 11 of 28 species used in the seed mix persist 12 years post-fire. The reseeded treatment showed greater overall diversity than burned and unburned treatments. Succulent and shrub cover were significantly reduced by fire while subshrub cover was significantly greater in the reseeded treatment. Sixteen species showed significant difference in distribution of cover between treatments.
Fire appears to impact plant community composition across Arizona Upland sites. Choosing species to include in seed mixes for post-fire reseeding, based on knowledge of pre-fire species composition and individual species’ fire responses, may be a useful tool to promote post-fire plant community recovery.
ContributorsBarron, Kara Lynn (Author) / Pigg, Kathleen B (Thesis advisor) / Stromberg, Juliet (Thesis advisor) / Makings, Elizabeth (Committee member) / McCue, Kimberlie (Committee member) / Arizona State University (Publisher)
Created2018
Description
ABSTRACT
Modern management techniques to maintain rangelands and deter encroachment of juniper into grassland habitats currently includes fire prescription. Additionally, a large body of research has indicated that fire has multiple benefits to grasslands resulting in increased diversity of flora and fauna. In the semi-arid grassland of the Agua Fria National Monument, fire treatments may be able to provide similar advantages. This study considers two methods of fire prescription on the Agua Fria National Monument within central Arizona: 1) Juniper thinning with pile burning; 2) Broadcast burning.
The Agua Fria National Monument upland ecosystem has limited research focusing on semi-arid grassland and juniper stand’s response to implemented treatments over time. The four year monitoring duration of this study aids in assessing the outcome of treatments and reaching the objectives of the management plan.
Vegetation in 981 quadrats was measured for species richness, cover, densities, height, and biomass during the fire prescription period from 2009 through 2013. The study was divided into two treatment types: 1) Juniper cutting and pile burn; 2) Broadcast burn areas in open grasslands.
Results of this study provide consistent examples of vegetative change and community movement towards positive response. Percent composition of overall vegetation is 5 – 30% with >50% of litter, bare ground and rock cover. Juniper sites have immediate consequences from tree thinning activities that may be beneficial to wildlife, particularly as connective corridors pronghorn antelope. Grass height was significantly reduced as well as forb density. Forbs that are highly responsive to environmental factors indicate an increase after the second year. Analysis results from grasslands indicated that cactus and unpalatable shrubs are reduced by fire but a return to pre-burn conditions occur by the third year after fire disturbance. Percent cover of perennial grasses has shown a slow increase. Wright’s buckwheat, a palatable shrub, has increased in density and height, indicating fire adaptations in the species. Species richness was reduced in the first year but increase in density continues into the third year after burn.
Modern management techniques to maintain rangelands and deter encroachment of juniper into grassland habitats currently includes fire prescription. Additionally, a large body of research has indicated that fire has multiple benefits to grasslands resulting in increased diversity of flora and fauna. In the semi-arid grassland of the Agua Fria National Monument, fire treatments may be able to provide similar advantages. This study considers two methods of fire prescription on the Agua Fria National Monument within central Arizona: 1) Juniper thinning with pile burning; 2) Broadcast burning.
The Agua Fria National Monument upland ecosystem has limited research focusing on semi-arid grassland and juniper stand’s response to implemented treatments over time. The four year monitoring duration of this study aids in assessing the outcome of treatments and reaching the objectives of the management plan.
Vegetation in 981 quadrats was measured for species richness, cover, densities, height, and biomass during the fire prescription period from 2009 through 2013. The study was divided into two treatment types: 1) Juniper cutting and pile burn; 2) Broadcast burn areas in open grasslands.
Results of this study provide consistent examples of vegetative change and community movement towards positive response. Percent composition of overall vegetation is 5 – 30% with >50% of litter, bare ground and rock cover. Juniper sites have immediate consequences from tree thinning activities that may be beneficial to wildlife, particularly as connective corridors pronghorn antelope. Grass height was significantly reduced as well as forb density. Forbs that are highly responsive to environmental factors indicate an increase after the second year. Analysis results from grasslands indicated that cactus and unpalatable shrubs are reduced by fire but a return to pre-burn conditions occur by the third year after fire disturbance. Percent cover of perennial grasses has shown a slow increase. Wright’s buckwheat, a palatable shrub, has increased in density and height, indicating fire adaptations in the species. Species richness was reduced in the first year but increase in density continues into the third year after burn.
ContributorsCole-Snow, Kimberly Sue (Author) / Alford, Eddie (Thesis advisor) / Miller, William (Committee member) / Green, Douglas (Committee member) / Arizona State University (Publisher)
Created2015
Description
Amsonia kearneyana is an endangered herbaceous plant endemic to a small area of the Baboquivari Mountains in southern Arizona. It exists in two distinct habitat types: 1) along the banks of a lower elevation ephemeral stream in a xeroriparian community, and 2) a higher elevation Madrean oak woodland on steep mountain slopes. Half of the largest known montane population (Upper Brown Canyon) was burned in a large fire in 2009 raising questions of the species capacity to recover after fire. This research sought to understand how the effects of fire will impact A. kearneyana's ability to recruit and survive in the burned versus unburned areas and in the montane versus xeroriparian habitat.
I compared population size, abiotic habitat characteristics, leaf traits, plant size, and reproductive output for plants in each habitat area for three years. Plants in the more shaded unburned montane area, the most populated population, presented with the most clonal establishment but produced the least amount of seeds per plant. The unshaded burned area produced more seeds per plant than in the unburned area. Lower Brown Canyon, the xeroriparian area, had the fewest plants, but produced the most seeds per plant while experiencing higher soil temperature, soil moisture, photosynthetically active radiation, and canopy cover than the montane plants. This could indicate conditions in Lower Brown Canyon are more favorable for seed production.
Despite ample seed production, recruitment is rare in wild plants. This study establishes germination requirements testing soil type, seed burial depth, temperature regimes, and shade treatments. Trials indicate that A. kearneyana can germinate and grow in varied light levels, and that soil type and seed burial depth are better predictors of growth than the degree of shade.
Finally, this study examined the law, regulation, policy, and physiological risks and benefits of a new management strategy and suggests that "conservation by dissemination" is appropriate for A. kearneyana. Conservation by dissemination is the idea that a protected plant species can be conserved by allowing and promoting the propagation and sale of plants in the commercial market with contingent collection of data on the fate of the sold individuals.
I compared population size, abiotic habitat characteristics, leaf traits, plant size, and reproductive output for plants in each habitat area for three years. Plants in the more shaded unburned montane area, the most populated population, presented with the most clonal establishment but produced the least amount of seeds per plant. The unshaded burned area produced more seeds per plant than in the unburned area. Lower Brown Canyon, the xeroriparian area, had the fewest plants, but produced the most seeds per plant while experiencing higher soil temperature, soil moisture, photosynthetically active radiation, and canopy cover than the montane plants. This could indicate conditions in Lower Brown Canyon are more favorable for seed production.
Despite ample seed production, recruitment is rare in wild plants. This study establishes germination requirements testing soil type, seed burial depth, temperature regimes, and shade treatments. Trials indicate that A. kearneyana can germinate and grow in varied light levels, and that soil type and seed burial depth are better predictors of growth than the degree of shade.
Finally, this study examined the law, regulation, policy, and physiological risks and benefits of a new management strategy and suggests that "conservation by dissemination" is appropriate for A. kearneyana. Conservation by dissemination is the idea that a protected plant species can be conserved by allowing and promoting the propagation and sale of plants in the commercial market with contingent collection of data on the fate of the sold individuals.
ContributorsYost, Tyna (Author) / Stromberg, Juliet (Thesis advisor) / McCue, Kimberlie (Committee member) / Bradshaw-Schulz, Karen (Committee member) / Arizona State University (Publisher)
Created2015
Description
It’s no secret that wetlands have dramatically declined in the arid and semiarid American West, yet the small number of wetlands that persist provide vital ecosystem services. Ciénega is a term that refers to a freshwater arid-land wetland. Today, even in areas where ciénegas are prominent they occupy less than 0.1% of the landscape. This investigation assesses the distribution of vascular plant species within and among ciénegas and address linkages between environmental factors and wetland plant communities. Specifically, I ask: 1) What is the range of variability among ciénegas, with respect to wetland area, soil organic matter, plant species richness, and species composition? 2) How is plant species richness influenced locally by soil moisture, soil salinity, and canopy cover, and regionally by elevation, flow gradient (percent slope), and temporally by season? And 3) Within ciénegas, how do soil moisture, soil salinity, and canopy cover influence plant species community composition? To answer these questions I measured environmental variables and quantified vegetation at six cienegas within the Santa Cruz Watershed in southern Arizona over one spring and two post-monsoon periods. Ciénegas are highly variable with respect to wetland area, soil organic matter, plant species richness, and species composition. Therefore, it is important to conserve the ciénega landscape as opposed to conserving a single ciénega. Plant species richness is influenced negatively by soil moisture, positively by soil salinity, elevation, and flow gradient (percent slope), and is greater during the post-monsoon season. Despite concerns about woody plant encroachment reducing biodiversity, my investigation suggests canopy cover has no significant influence on ciénega species richness. Plant species community composition is structured by water availability at all ciénegas, which is consistent with the key role water availability plays in arid and semiarid regions. Effects of canopy and salinity structuring community composition are site specific. My investigation has laid the groundwork for ciénega conservation by providing baseline information of the ecology of these unique and threatened systems. The high variability of ciénega wetlands and the rare species they harbor combined with the numerous threats against them and their isolated occurrences makes these vanishing communities high priority for conservation.
ContributorsWolkis, Dustin (Author) / Stromberg, Juliet C. (Thesis advisor) / Hall, Sharon (Committee member) / Salywon, Andrew (Committee member) / Makings, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2016
Description
The increased number of novel pathogens that potentially threaten the human population has motivated the development of mathematical and computational modeling approaches for forecasting epidemic impact and understanding key environmental characteristics that influence the spread of diseases. Yet, in the case that substantial uncertainty surrounds the transmission process during a rapidly developing infectious disease outbreak, complex mechanistic models may be too difficult to be calibrated quick enough for policy makers to make informed decisions. Simple phenomenological models that rely on a small number of parameters can provide an initial platform for assessing the epidemic trajectory, estimating the reproduction number and quantifying the disease burden from the early epidemic phase.
Chapter 1 provides background information and motivation for infectious disease forecasting and outlines the rest of the thesis.
In chapter 2, logistic patch models are used to assess and forecast the 2013-2015 West Africa Zaire ebolavirus epidemic. In particular, this chapter is concerned with comparing and contrasting the effects that spatial heterogeneity has on the forecasting performance of the cumulative infected case counts reported during the epidemic.
In chapter 3, two simple phenomenological models inspired from population biology are used to assess the Research and Policy for Infectious Disease Dynamics (RAPIDD) Ebola Challenge; a simulated epidemic that generated 4 infectious disease scenarios. Because of the nature of the synthetically generated data, model predictions are compared to exact epidemiological quantities used in the simulation.
In chapter 4, these models are applied to the 1904 Plague epidemic that occurred in Bombay. This chapter provides evidence that these simple models may be applicable to infectious diseases no matter the disease transmission mechanism.
Chapter 5, uses the patch models from chapter 2 to explore how migration in the 1904 Plague epidemic changes the final epidemic size.
The final chapter is an interdisciplinary project concerning within-host dynamics of cereal yellow dwarf virus-RPV, a plant pathogen from a virus group that infects over 150 grass species. Motivated by environmental nutrient enrichment due to anthropological activities, mathematical models are employed to investigate the relevance of resource competition to pathogen and host dynamics.
Chapter 1 provides background information and motivation for infectious disease forecasting and outlines the rest of the thesis.
In chapter 2, logistic patch models are used to assess and forecast the 2013-2015 West Africa Zaire ebolavirus epidemic. In particular, this chapter is concerned with comparing and contrasting the effects that spatial heterogeneity has on the forecasting performance of the cumulative infected case counts reported during the epidemic.
In chapter 3, two simple phenomenological models inspired from population biology are used to assess the Research and Policy for Infectious Disease Dynamics (RAPIDD) Ebola Challenge; a simulated epidemic that generated 4 infectious disease scenarios. Because of the nature of the synthetically generated data, model predictions are compared to exact epidemiological quantities used in the simulation.
In chapter 4, these models are applied to the 1904 Plague epidemic that occurred in Bombay. This chapter provides evidence that these simple models may be applicable to infectious diseases no matter the disease transmission mechanism.
Chapter 5, uses the patch models from chapter 2 to explore how migration in the 1904 Plague epidemic changes the final epidemic size.
The final chapter is an interdisciplinary project concerning within-host dynamics of cereal yellow dwarf virus-RPV, a plant pathogen from a virus group that infects over 150 grass species. Motivated by environmental nutrient enrichment due to anthropological activities, mathematical models are employed to investigate the relevance of resource competition to pathogen and host dynamics.
ContributorsPell, Bruce (Author) / Kuang, Yang (Thesis advisor) / Chowell-Puente, Gerardo (Committee member) / Nagy, John (Committee member) / Kostelich, Eric (Committee member) / Gardner, Carl (Committee member) / Arizona State University (Publisher)
Created2016
Description
De Plantis Aegypti is a medical botany text from 1592, written by Prospero Alpini in Latin. In this text, Alpini details a variety of plants native and grown in Egypt, how they are grown, how they are processed, what they look like, and what if any edible and medical uses are documented. This project focused on transcribing and editing the Latin text, translating the Latin text into English, and comparing the medical claims to the modern scientific literature. This is the first translation of this text into English or any other language. Alpini also wrote two other books, which also have never been translated. The intended goal was to demonstrate that renaissance scholars understood medicine well, if not the mechanisms through which those medicines worked. After analyzing the modern scientific literature on the plants mentioned within the text, it was found that every medical use referenced in the text was either directly supported, indirectly supported, or there was no data from the literature. In other words, none of the medical uses were found to be disproved. On the other hand, quite a few of the plants actually had similar efficacies as modern pharmaceuticals. In addition to the notes on the modern science, there are also quite a few notes based on the grammar and the orthography of the text. This project is but a sampling of the plants mentioned De Plantis Aegypti, there are dozens more, which I plan on translating and doing a similar analysis on at a later date.
ContributorsPlamondon, Ian Lee (Author) / Poudrier, Almira (Thesis director) / Bjork, Robert (Committee member) / Egmond, Warren (Committee member) / School of Historical, Philosophical and Religious Studies (Contributor) / School of Molecular Sciences (Contributor) / School of International Letters and Cultures (Contributor) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Xylem conduits, a primary feature of most terrestrial plant taxa, deliver water to photosynthetic tissues and play a critical role in plant water relations and drought tolerance. Non-succulent woody taxa generally follow a universal rate of tip-to-base conduit widening such that hydraulic resistance remains constant throughout the plant stem. Giant cacti inhabit arid regions throughout the Americas and thrive in water-limited environments by complimenting water-storing succulent tissues with resource-efficient Crassulacean Acid Metabolism. Considering these adaptations, the objectives of this study were threefold: 1) determine whether xylem conduits in columnar cacti follow universal scaling theory as observed in woody taxa; 2) evaluate whether xylem hydraulic diameter is inversely correlated with xylem vessel density; and 3) determine whether xylem double-wall thickness-to-span ratio and other hydraulic architectural traits are convergent among phylogenetically diverse cactus species. This thesis investigates the xylem anatomy of nine cactus species native to the Sonoran Desert of Arizona and Mexico, the tropical dry forests of southern Mexico, and the Alto Plano region of Argentina. Soft xylem tissues closest to the stem apex underwent a modified polyethylene glycol treatment to stabilize for sectioning with a sledge microtome. Across all species: hydraulic diameter followed a basipetal widening rate of 0.21 (p < 0.001), closely matching the universal rate of 0.20 for woody taxa; and xylem vessel density was inversely correlated with both length from stem apex (p < 0.001) and hydraulic diameter (p < 0.001). Double-wall thickness-to-span ratio had little to no significant correlation with either length from stem apex or hydraulic diameter. There was no significant difference in hydraulic architectural trait patterns between phylogenetically diverse species with various stem morphologies, nor was there a significant correlation between conduit widening rates and volume-to-surface-area ratios.
This study demonstrates that giant cacti follow similar internal anatomical constraints as non-succulent woody taxa, yet stem succulence and water storage behavior in cacti remain separate from internal hydraulic architecture, allowing cacti to thrive in arid environments. Understanding how cacti cope with severe water limitations provides new insights on evolutionary constraints of stem succulents as they functionally diverged from other life forms.
ContributorsCaspeta, Ivanna (Author) / Hultine, Kevin (Thesis advisor) / Throop, Heather (Thesis advisor) / Hernandez, Tania (Committee member) / Arizona State University (Publisher)
Created2023