Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Geomorphology, biodiversity and ecosystem function, and food web dynamics in large riverscapes(Montana State University - Bozeman, College of Letters & Science, 2021) Scholl, Eric Arthur; Chairperson, Graduate Committee: Wyatt F. Cross; This is a manuscript style paper that includes co-authored chapters.Humans have transformed the Earth's surface so extensively that we now play a dominant role in regulating geomorphological processes around the world. These effects are particularly prevalent in large rivers, which despite their high biophysical complexity, face widespread habitat alteration and simplification. The way species respond to such changes will unquestionably impact the structure and function of ecosystems, with cascading effects on numerous goods and services they provide. Consequently, efforts to understand how the physical habitat template shapes the structure and function of larger river ecosystems are critically needed to predict how future perturbations will impact these imperiled and iconic environments. My dissertation blends approaches from the physical and ecological sciences to uncover connections between the geophysical habitat template, biodiversity and ecosystem function, and the dynamics of food webs in large riverscapes. My questions were: 1) what are the spatial patterns and potential drivers of riverbed habitat, and how do they relate to process domain structures in large rivers? 2) how does the geophysical habitat template influence connections between invertebrate diversity and secondary production? and 3) how are trophic interactions supporting the federally endangered Pallid Sturgeon (Scaphirhynchus albus) shaped by the geophysical habitat template? I found consistent patterns of nested patchiness in riverbed substrate, indicating that multiple factors operating at different scales influence spatial patterns of substrate in the Missouri and Yellowstone Rivers. Invertebrate assemblages were tied to attributes of the geophysical habitat template, with strong relationships between large sediments and diversity. Invertebrate diversity, in turn, was positively related to secondary production, with the most diverse assemblages found in secondary production 'hotspots'. Finally, I found a general relationship between habitat diversity and trophic interaction strengths supporting Pallid Sturgeon, with geophysically diverse areas containing much weaker, and thus potentially stabilizing, interactions than homogenous areas. Additionally, habitat characteristics, such as sediment size, intensified these effects. Together, the chapters of my dissertation broadly highlight the role of nature's stage in governing patterns in biodiversity, secondary production, and trophic interactions across large and dynamic riverscapes, and provide empirical insights for guiding future management and conservation of large rivers in an increasingly simplified world.Item Wetland biodiversity in Grand Teton National Park(Montana State University - Bozeman, College of Letters & Science, 2022) Levandowski, Mary Lynn; Chairperson, Graduate Committee: Andrea Litt; Andrea R. Litt was a co-author of the article, 'Spatial and temporal isolation and size of wetlands influence richness and functional composition of aquatic macroinvertebrates' which is contained within this thesis.; Andrea R. Litt, Megan F. McKenna, Shan Burson and Kristin L. Legg were co-authors of the article, 'Multi-method biodiversity assessments from wetlands in Grand Teton National Park' in the journal 'Ecological indicators' which is contained within this thesis.Freshwater wetlands support high biodiversity, yet many wetlands are subject to shifts in precipitation and temperature under projected climate patterns. These changes can alter wetland hydrological regimes, potentially leading to longer or more frequent dry periods, with effects that differ among taxa. In this thesis we aim to build on the understanding about biodiversity in wetlands and how these species may be affected by climate change, in hopes of providing information for land management. To accomplish these goals, we first focused on macroinvertebrates, a group that employs diverse strategies for surviving wetland drying. We explored the roles of wetland size, spatial isolation, and temporal isolation on macroinvertebrate richness and community composition. In summer 2018, we collected macroinvertebrates from 18 wetlands in Grand Teton National Park. We found macroinvertebrate family richness increased with wetland depth and slower rates of drying. We also found the interaction between spatial and temporal isolation explained the most variation in community composition for all the life history strategies we examined. Second, we explored the utility of different automated tools to monitor biodiversity in wetlands. In 2017, we placed wildlife cameras, as well as acoustic (audible and ultrasonic) recorders at 4 permanent wetlands in Grand Teton National Park for a week in June and August; we also completed a visual survey during each of these time intervals. We compared the number and type of species detected by each method over the summer to evaluate the effectiveness of each method for monitoring. Using wildlife cameras, in addition to visual surveys, increased the observation time at surveyed wetlands, captured complementary species, and recorded dynamics in the water level during the summer. These two chapters provide insights about how changes resulting from increased drying may affect one of the most biodiverse taxa and offer methods that allow monitoring of many taxa simultaneously.Item Distributions, abundances, and movements of small, nongame fishes in a large Great Plains river network(Montana State University - Bozeman, College of Letters & Science, 2019) Duncan, Michael Bennett; Chairperson, Graduate Committee: Alexander V. ZaleThe Yellowstone River is the longest unimpounded river in the conterminous United States and was thought to support a diverse fish assemblage; however, comprehensive data on the small nongame fish assemblage was lacking. I evaluated the sampling methods often used to capture small-bodied fishes in the channel margins of large Great Plains rivers, determined the distributions and abundances of these fishes in the Yellowstone River, characterized the movements of selected native cyprinids between the Yellowstone River and its tributaries, and assessed assemblage differences between the Yellowstone and Missouri rivers. Catch-per-unit-effort, species richness, and ranges of total lengths were greater in fyke net catches than in seine catches. Forty-two species (24 native and 18 nonnative) were captured in fyke nets in the lower Yellowstone River. Emerald Shiners Notropis atherinoides, Western Silvery Minnows Hybognathus argyritis, Flathead Chubs Platygobio gracilis, Sand Shiners Notropis stramineus, and Longnose Dace Rhinichthys cataractae composed nearly 94% of fyke net catch. Sturgeon Chubs Macrhybopsis gelida, Channel Catfish Ictalurus punctatus, Flathead Chubs, Stonecats Noturus flavus, and Sicklefin Chubs Macrhybopsis meeki composed 89% of the otter trawl catch. Sicklefin Chubs were captured as far as 18 river kilometers upstream of Glendive, Montana; Sturgeon Chubs were captured as far upstream as the Tongue River confluence. Otolith microchemistry analysis revealed that 69% of Western Silvery Minnows, 65% of Flathead Chubs, and 42% of Sand Shiners moved between main-stem and tributary habitats. The timing, frequencies, and patterns of movements varied among species. In my comparison of the Yellowstone and Missouri river fish assemblages, native and nonnative species richness were highest in Yellowstone River fyke net catches but proliferation of nonnative species was low. Total CPUE was highest in the Yellowstone River (median = 152 fish/net night), intermediate in the Missouri River below the Yellowstone River confluence (44 fish/net night), and lowest in the Missouri River above the confluence (21 fish/net night). Collectively, these studies provide a better understanding of the biotic and abiotic factors that help influence the distributions, abundances, and diversity of life-history strategies of small, nongame fish in Great Plains rivers.Item Biodiversity potential in the Pacific and Inland Northwest : the relative importance of forest structure and available energy in driving species diversity(Montana State University - Bozeman, College of Letters & Science, 2007) Verschuyl, Jacob Pieter; Chairperson, Graduate Committee: Andrew J. HansenCurrently, the most common strategy of forest biodiversity managers in the Pacific and Inland Northwest (PINW) is to maintain structural complexity within forest stands and create the full range of seral stages across the landscape. Recent advances in ecological theory reveal that biodiversity at regional to continental scales is strongly influenced by available energy (i.e. factors influencing vegetative growth such as precipitation, temperature, radiation, soil fertility). We hypothesized bird species richness (BSR) exhibits a positive or unimodal relationship with energy across landscapes and the relationship between energy and BSR within a landscape is positive in energy limited landscapes and flat or decreasing in energy rich landscapes. Additionally, we hypothesized that structural complexity explains a lower percentage of the variation in BSR in energy limited environments and higher percentage in energy rich environments and that the slope of the relationship between structural complexity and BSR is greatest in energy rich environments.Item Change in deciduous woody vegetation, implications of increased willow (Salix spp.) growth for bird species diversity, and willow species composition in and around Yellowstone National Park's Northern range(Montana State University - Bozeman, College of Letters & Science, 2009) Baril, Lisa Marie; Chairperson, Graduate Committee: Andrew J. HansenDeciduous woody vegetation (DWV) in Yellowstone's northern range is a rare, but important habitat type. Including willow, alder, aspen, and cottonwood, DWV was limited in height and areal extent since the early 1900s. Since the mid-1990s; however, DWV has increased in height and areal extent in some locations. Previous studies regarding DWV change have focused on quantifying change in vegetation growth in areas of limited extent and none have quantified increased DWV growth at the scale of the landscape. Furthermore, no studies have evaluated the implications for increased growth of DWV for wildlife in the region or how DWV species themselves may influence rates of growth. In this thesis I evaluate change in DWV within wetland and riparian areas using aerial photographs from 1991 and 2006. I also investigate how an increase in willow, the dominant component of DWV in the region, has likely influenced bird diversity. Finally, since willow species vary with respect to genetic limitations on growth and reproduction that in turn may influence observed patterns of growth; I examine willow species composition across the northern range. Results of the air photo interpretation revealed a 170% increase in DWV. Most plots that increased did so by recruitment rather than densification; however, DWV was difficult to detect below 100 cm indicating that the number of plots increasing by recruitment may have been overestimated. Bird community variables were examined in three willow growth conditions: height suppressed, recently released, and previously tall (tall prior to observed increase in growth). I found that willow structure generally increased in complexity from structurally simple height suppressed willows to structurally complex previously tall willows and that this allowed for greater bird richness, abundance, diversity, and the abundance of several willow dependent bird species. I also found that willow species composition was similar and diverse between the released and previously tall condition, but that the suppressed condition was dominated by a singe species. I conclude that increased DWV has allowed for greater bird diversity in the northern range and that increased willow growth in the suppressed condition may be influenced by species composition there.