Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


37909.pdf (5.93 MB)

ETD Abstract Container

Abstract Header

Saguaro Cactus (Carnegiea gigantea) Growth and Population Dynamics in Multiple Physiographic Settings of Saguaro National Park, Arizona, USA

Conver, Joshua L
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613745513093036

Abstract Details

2020, PhD, University of Cincinnati, Arts and Sciences: Geography.
The saguaro (Carnegiea gigantea [Engelm.] Britton and Rose) is a long-lived, columnar cactus and a keystone species in Sonoran Desert ecology. The saguaro is an iconic symbol of the U.S. American Southwest with a long and deep ethnobotanical history. In the northern Sonoran Desert, saguaro research is focused on two primary domains: the influence of climate on growth and reproduction and the anthropogenic impacts of human activity on the species and to the landscape. Saguaro growth and establishment are strongly influenced by the timing and amount of summer precipitation, and winter minimum temperature is an additional control. Anthropogenic historic land uses in the Southwest significantly altered ecosystem function and vegetation community type and structure throughout the region. Understanding the changes in community form and process provides a basis for ecological restoration. Saguaro National Park (SNP) is comprised of two districts on the east and west sides of Tucson, Arizona, and contains historic plots that have been monitored for more than 80 years. This dissertation utilizes some of the oldest demographic data available for the species to examine the physical geographic, anthropogenic, and climatic conditions and processes that affect saguaro growth and establishment at multiple spatial and temporal scales. The stratified plot-based approach utilized in this dissertation captures the response of the saguaro to climatic and landscape settings in different vegetational communities and across gradients of slope, aspect, and elevation within SNP. Additionally, much of the data collected for this dissertation are publicly available and serve as the latest snapshot in time of the saguaro population for the work of a next generation of researchers and public land stewards. This dissertation is presented in journal article format. Chapter 2 analyzes the demographic change over 75 years within a population of saguaros in an area of SNP that has a legacy of woodcutting and grazing and presents an ecological history of the landscape. As land use pressures eased over time, saguaro establishment recovered and an elderly population in 1941 transitioned to a juvenile-dominated population in 2012. Climate is now the primary controlling factor for establishment in this area. Chapter 3 examines the interaction of drought and landscape position on saguaro establishment patterns. Different habitats and landscape positions demonstrated different responses to drought; lower elevations and landscape positions were affected more severely than upslope areas at higher elevations. Determining local variation in establishment rates provides understanding of the potential future distribution of the species given predictions of future increases in aridity for the region. Chapter 4 revisits the Steenbergh and Lowe age-height curve and determines the variation in growth rate in bajada and rocky habitats through time. The age of saguaros may be reliably determined from the height of the plant, but spatial and temporal variations of growth rate may affect future height distributions and reproductive potential associated with flowering and branching. This paper discusses the ecological and scientific consequences of spatiotemporal deviations from predicted growth.
Nicholas Dunning, Ph.D. (Committee Chair)
Richard Beck, Ph.D. (Committee Member)
Kevin Raleigh, Ph.D. (Committee Member)
Vernon Scarborough, Ph.D. (Committee Member)
Susanna Tong, Ph.D. (Committee Member)
129 p.
Geography
long term monitoring; national park; arid environments; natural resources; citizen science; cactaceae

Recommended Citations

Citations

  • Conver, J. L. (2020). Saguaro Cactus (Carnegiea gigantea) Growth and Population Dynamics in Multiple Physiographic Settings of Saguaro National Park, Arizona, USA [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613745513093036

    APA Style (7th edition)

  • Conver, Joshua. Saguaro Cactus (Carnegiea gigantea) Growth and Population Dynamics in Multiple Physiographic Settings of Saguaro National Park, Arizona, USA. 2020. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613745513093036.

    MLA Style (8th edition)

  • Conver, Joshua. "Saguaro Cactus (Carnegiea gigantea) Growth and Population Dynamics in Multiple Physiographic Settings of Saguaro National Park, Arizona, USA." Doctoral dissertation, University of Cincinnati, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613745513093036

    Chicago Manual of Style (17th edition)

ucin1613745513093036
241
© 2020, some rights reserved.Creative Commons License Saguaro Cactus (Carnegiea gigantea) Growth and Population Dynamics in Multiple Physiographic Settings of Saguaro National Park, Arizona, USA by Joshua L Conver is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.