Date of Award:
5-2016
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Watershed Sciences
Department name when degree awarded
Watershed Sciences and Ecology Center
Committee Chair(s)
Joseph M. Wheaton
Committee
Joseph M. Wheaton
Committee
Brett B. Roper
Committee
Nancy J. Huntly
Committee
Michael L. Scott
Committee
James A. Lutz
Abstract
Flow regime, the magnitude, duration and timing of streamflow, controls the development of floodplain landforms on which riparian vegetation communities assemble. Streamflow scours and deposits sediment, structures floodplain soil moisture dynamics, and transports propagules. Flow regime interacts with environmental gradients like climate, land-use, and biomass-removing disturbance to shape riparian plant distributions across landscapes. These gradients select for groups of riparian plant species with traits that allow them to establish, grow, and reproduce on floodplains – riparian vegetation guilds. Here I ask, what governs the distributions of groups of similar riparian plant species across landscapes? To answer this question, I identify relationships between riparian vegetation guilds and communities and environmental gradients across the American West. In Chapter One, I discuss guild-based classification in the context of community ecology and streams. In Chapter Two, I identified five woody riparian vegetation guilds across the interior Columbia and upper Missouri River Basins, USA, based on species’ traits and morphological attributes. I modeled guild occurrence across environmental gradients, including climate, disturbance, channel form attributes that reflect hydrology, and relationships between guilds. I found guilds’ distributions were related to hydrology, disturbance, and competitive or complementary interactions (niche partitioning) between co-occurring guilds. In Chapter Three, I examine floodplain riparian vegetation across the American West, identifying how hydrology, climate, and floodplain alteration shape riparian vegetation communities and their guilds. I identified eight distinct plant communities ranging from high elevation mixed conifer forests to gallery cottonwood forests to Tamarisk-dominated novel shrublands. I aggregated woody species into four guilds based on their traits and morphological attributes: an evergreen tree guild, a mesoriparian shrub guild, a mesoriparian tree guild, and a drought and hydrologic disturbance tolerant shrub guild. Communities and guilds’ distributions were governed by climate directly, and indirectly as mediated through streamflow. In Chapter Four, I discuss the utility of guild-based assessments of riparian vegetation, current limitations to these approaches, and potential future applications of the riparian vegetation guild concept to floodplain conservation and management. The classification of vegetation into functional trait-based guilds provides a flexible, framework from which to understand riparian biogeography, complementing other models frameworks for riparian vegetation.
Checksum
f41d3d5a6fc53f788144871cb4d08f19
Recommended Citation
Hough-Snee, Nathaniel, "Relationships between Riparian Vegetation, Hydrology, Climate and Disturbance across the Western United States" (2016). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 5018.
https://digitalcommons.usu.edu/etd/5018
Included in
Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .