Theses and Dissertations at Montana State University (MSU)
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Item Impacts of forest mortality on streamflow in whitebark pine forests within the greater Yellowstone ecosystem(Montana State University - Bozeman, College of Letters & Science, 2024) Rautu, Teodora Stefana; Co-chairs, Graduate Committee: Brian V. Smithers and Danielle E. M. UlrichIncreasing forest mortality across the western U.S. raises concerns about its impact on streamflow. The hydrologic role of whitebark pine (Pinus albicaulis Engelm.) is of particular interest given its ongoing decline and prevalence at the upper treeline where precipitation is highest. Understanding the link between disturbed whitebark pine forests and streamflow is essential for better informing water resource management. In Chapter One, I investigated streamflow changes in two Wyoming whitebark pine watersheds: Upper Wind River (53% area affected by beetle outbreak) and Buffalo Fork (53% area affected by beetle outbreak and fire). Streamflow significantly increased post-beetle for Upper Wind River but did not significantly change post-disturbance for Buffalo Fork, attributed to the fire's limited spatial extent and post- beetle effects potentially occurring in the pre-disturbance period. In Chapter Two, I integrated Leaf Area Index into a hydrologic model to reflect changing canopy conditions and assessed water balance variables that drove the observed changes in streamflow in Chapter One. I found that an increase in annual precipitation primarily led to the increase in observed streamflow more so than forest mortality, and snowpack and snowmelt were consistent predictors of streamflow metrics. My findings suggest monitoring snow dynamics for accurate real-time and future streamflow forecasting. In Chapter Three, I used streamflow field data and the same hydrologic model to assess the impact of increasing tree mortality on streamflow within a whitebark pine- dominated watershed in Big Sky, Montana. After simulating mortality levels ranging from 0-90% for one year, tree mortality did not substantially impact streamflow until the 90% mortality level where annual flow and late summer flow substantially increased. Considering that mortality levels between 25-50% are more representative of whitebark pine mortality in one year, the lack of substantial impacts on snowpack and streamflow at the 25-50% mortality levels challenges the traditional assumption that whitebark pine mortality would lead to reduced snowpack and reduced late summer flow in open watersheds with 30% forest cover. Future studies should assess the multi-decade impacts of whitebark pine mortality on hydrologic processes and consider species differences in evapotranspiration as other subalpine species replace whitebark pine.Item Effectiveness of the nature-like fishway at Huntley Diversion Dam, Yellowstone River, Montana(Montana State University - Bozeman, College of Letters & Science, 2022) Anderson, Ian Richard; Chairperson, Graduate Committee: Alexander V. ZaleWe evaluated passage of a diverse fish assemblage through the nature-like fishway built around Huntley Diversion Dam, the uppermost of six low-head diversion dams on the Yellowstone River in Montana. Although nature-like fishways purportedly facilitate the passage of many species, relatively few have been evaluated, particularly on large rivers with unregulated discharge regimes. We examined seasonal and diel use of the Huntley fishway, quantified efficiencies and temporal metrics, and determined which factors influenced attraction and passage. We implanted > 3,500 fish of 14 species with passive integrated transponder tags, released most fish 250 m downstream of the fishway, and used stationary antennas to monitor movements of fish through the fishway in 2019 and 2020. Seasonal use of the fishway was generally associated with pre-spawning movements and occurred from April to August annually, and diel use reflected the known biology of each species. Attraction efficiencies were apparently low (usually < 50%), probably because of low motivation or the inability of fish to locate the entrance. Suckers released on opposite riverbanks downstream of the fishway were similarly successful at locating the entrance. Entrance efficiencies were usually > 90%. Both transit and passage efficiencies were usually > 60%, but fewer individuals (particularly among certain species) successfully passed than were able to transit to near the fishway exit. High river discharges were associated with decreased passage success and increased exit delays, probably because of problematic hydraulic conditions near the exit. Conditions throughout the rest of the fishway were appropriate, as most fish transited to near the exit in < 1 h regardless of discharge. Fourteen species passed upstream, demonstrating the functionality of nature-like fishways on large, unregulated rivers. However, the placement of such fishways must be thoughtfully considered to ensure that they remain effective over a wide range of environmental conditions.Item Small scale denil development for use in headwater streams in southwest Montana(Montana State University - Bozeman, College of Engineering, 2021) Conley, Megan Elizabeth; Chairperson, Graduate Committee: Kathryn Plymesser; Katey Plymesser, Kevin Kappenman, Matt Blank and Joel Cahoon were co-authors of the article, 'Arctic grayling (Thymallus arcticus) passage through a scaled denil fishway' submitted to the journal 'Journal of fish and wildlife management' which is contained within this thesis.The Big Hole River is located in an agricultural valley in Southwest Montana and is home to the last fluvial (river dwelling) population of Arctic grayling (Thymallus arcticus) in the contiguous United States. Grayling mostly populate the tributary streams in the upper portion of the watershed, where there are many irrigation diversions, which greatly fragments grayling's natural habitat. While many of these irrigation diversions have fish ladders installed at them to assist with habitat reconnection, these ladder become impassable when the water levels get too low in the system or irrigators chose to block the fish ladders in order to divert more water. This study investigated and characterized a smaller scale Denil fish ladder that would use less water while providing adequate fish passage. Three different flow rate calculations were applied to a series of scaled Denils to compare to the expected flow rates of the full scale Denil to determine the scaled sizes to construct. A 0.6 scale and a 0.75 scale Denil were selected and hydraulic lab testing confirmed that 25.4 cm baffle spacing was the best for both scaled models. The fish swimming study, conducted at the outdoor flume at the Bozeman Fish Technology Center, used eight hatchery-raised grayling in each of the eight treatments. Each treatment was repeated 3 times using the 0.6-scale model for a total of 24 trials with 192 fish. Each treatment used a different combination of headwater depth (between 30.5 cm and 61.0 cm) and tailwater depth (between 15.2 cm and 61.0 cm). The grayling passed with near perfect success at all headwater and tailwater combinations except when the head difference between the headwater and tailwater was at its greatest (61.0 cm headwater and 15.2 cm tailwater). This preliminary study showed that grayling are willing to pass smaller-scale structures at a variety of flow rates but did not test a wide range of slopes, age classes or fish sizes. These results should be useful to water managers when looking to modify or install new Denil fishways in the Big Hole River Basin and around the western United States.Item Towards a more-than-human geography of the Yellowstone River(Montana State University - Bozeman, College of Letters & Science, 2020) Bergmann, Nicolas Timothy; Chairperson, Graduate Committee: Jamie McEvoy; Jamie McEvoy, Elizabeth A. Shanahan, Eric D. Raile, Anne Marie Reinhold, Geoffrey C. Poole and Clemente Izurieta were co-authors of the article, 'Thinking through levees: how political agency extends beyond the human mind' in the journal 'Annals of the American Association of Geographers' which is contained within this thesis.This dissertation conceptualizes the Yellowstone River, flowing more than 670 miles from its headwaters in the mountains of northwestern Wyoming to its confluence with the Missouri River in western North Dakota, as a more-than-human assemblage. Specifically, this dissertation asks the following overarching research question: How does a more-than-human approach to understanding the Yellowstone River further geographical conceptualizations of human-environment relationships? In order to answer this question, this dissertation investigates the more-than-human aspects of both historical and contemporary environmental conflicts within Montana's portion of the Yellowstone River Basin. Chapter 2 examines the relationship between instream flow water law, Montana Fish and Game, and the Yellowstone River Basin. Drawing from both critical legal geography and political ecology, it furthers understandings of instream flow water law as relationally co-constituted through both human and nonhuman forces. Chapter 2 also traces the influence of Montana Fish and Game's more-than-anthropocentric ethical position on interpretations of the 1973 Montana Water Use Act. Chapter 3 uses a morethan- human approach to examine the relationship between myth and the Yellowstone River. Specifically, this chapter combines existing geographical understandings of myth with theories of assemblage and affect in order to historicize and denaturalize mythic belief in the Yellowstone as the longest undammed or free-flowing river remaining in the United States. Chapter 4 advances more-than-human understandings of political agency through a reframing of human thought as a co-constitutional assemblage of human and nonhuman elements. Relying on a comparative case study approach and qualitative interview data from two Montana communities located along the lower Yellowstone River, this chapter supports its theoretical claims through an embodied and affective analysis of the communities' divergent flood risk perceptions. Chapter 5 closes this dissertation with reflections on the value of using a more-than-human geographical approach.Item Ecosystem engineering at the streambed: how net-spinning caddisflies influence substrate flow dynamics(Montana State University - Bozeman, College of Letters & Science, 2020) MacDonald, Michael Joseph; Chairperson, Graduate Committee: Lindsey Albertson; Lindsey K. Albertson and Geoffrey C. Poole were co-authors of the article, 'Ecosystem engineering at the streambed: how net-spinning caddisflies influence substrate flow dynamics' submitted to the journal 'Ecohydrology' which is contained within this thesis.The streambed is an ecotone between surface waters and underlying hyporheic systems. Identifying the controls on advective flow through this ecotone is critical to understanding the movement of energy and matter in streams. Hydropsychids (net-spinning caddisflies) are aquatic macroinvertebrate ecosystem engineers that influence streambed cohesion, yet evidence of direct influence on hydrologic processes is lacking. Utilizing a novel downward flow permeameter, we demonstrate how net-spinning caddisfly colonization of the streambed interstitia at moderate but common densities (2,000 m^-2) can reduce the vertical hydraulic conductivity (KV) by up to 55% in coarse sand and gravels (median diameter = 12.91 mm). Sediment columns incubated in artificial stream water occupied by caddisflies showed greater reductions in KV relative to those without caddisflies. Additionally, organic matter content within sediment columns showed that occupation by caddisflies resulted in nearly two-fold increases in organic matter AFDM. Our research shows that the ubiquitous and numerous net-spinning caddisflies are likely to modulate the exchange of channel and hyporheic water by constructing nets in open pore spaces, increasing flow resistance, and decreasing flow velocities, as well as stimulating organic matter deposition with potential consequences for biofilm growth. These results suggest that caddisfly induced reductions to flow may influence transfer processes occurring at the streambed ecotone, altering biogeochemical processes in streams.