Theses and Dissertations at Montana State University (MSU)
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Item Impacts of low-tech restoration methods on soil, vegetation, and livestock grazing in Montana's sagebrush steppe(Montana State University - Bozeman, College of Agriculture, 2024) Lowing, Nicholas Allen; Chairperson, Graduate Committee: Bok SowellIn the semi-arid rangelands of western North America, water is a limiting factor for plant growth. In Montana's high elevation rangelands, snowmelt is the primary source of water for ephemeral streams and mesic meadows. Wildlife and livestock rely on these areas especially when surrounding uplands have dried. Less snowpack and early melt times associated with climate change pose a threat to forage resources in this region. In 2018 and 2019, small rock restoration structures were constructed in seven drainages in southwest Montana with the intention of increasing resiliency in these systems. In this study we compare stream reaches with restoration structures to reaches without structures to assess the impacts of this technique on soil moisture, plant cover, diversity, evenness, and production. We observed cattle grazing within and adjacent to treated drainages to determine how they use the landscape. We used soil moisture probes to measure soil water content once per month in June-September of 2021 and 2022. We used 0.5m2 frames to estimate plant cover, diversity, and evenness June-September in both years. At the end of each growing season, vegetation frames were clipped and weighed to estimate production. Soil and vegetation sampling occurred in 54 reaches across 7 drainages. We observed cattle near four treated drainages in mornings and evenings to assess whether cattle prefer mesic or upland areas. Cattle observations occurred in July and August of 2021 and 2022. Using linear fixed effects models, we detected no differences (p > or = 0.05) in soil moisture between treated and untreated reaches during any sampling period. We detected no differences in vegetation cover, richness, diversity, or evenness in 92% of sampling periods. No differences in plant production were detected in 2021 or 2022. Cattle used mesic areas in greater proportion to their abundance on the landscape in both years (p < or = 0.0001). Our results indicate that these structures have not yet had major impacts on soil moisture or vegetation metrics. However, our results indicate that mesic meadows are an important resource for grazing cattle in southwest Montana's high- elevation rangelands, supporting the idea that these areas warrant restoration efforts.Item Ecological responses to meadow restoration in the sagebrush steppe of Montana(Montana State University - Bozeman, College of Agriculture, 2023) Robison, Laura Margery; Chairperson, Graduate Committee: Bok SowellIn the semi-arid landscapes of the Western United States, water is scarce. In the high-elevation sagebrush steppe of Southwest Montana, mesic meadows are primarily fed by melting snowpack. These meadows, often centered around an ephemeral stream, collect and store water in the soil. Between 60-80% of wildlife rely on meadows for resources when surrounding upland environments are dry. Warming temperatures and declining snowpack are threatening water resources in this region. Stream incision, often induced by historic land use, decreases water storage in surrounding meadows. In 2018 and 2019, rock restoration structures, typically less than 0.3 m tall, were installed in seven impaired catchments in Southwest Montana to mitigate climate change and incision by slowing and spreading water. Catchments spanned an ecological and abiotic gradient that accounts for over 1/3 of the variation within the sagebrush biome. We compared reaches with structures built to reaches without to assess the impact of restoration on average soil moisture, soil drying rate, water storage, water retention time after rainfall events, and sage-grouse chick food resources (plants and arthropods). We installed soil moisture probes at 24 reaches in 4 catchments, recording hourly measurements from June through September in 2020, 2021, and 2022. Using 0.5 m 2 frames, we estimated vegetation canopy cover at the species level once per month in June through September. We set 24 hr pitfall traps once per month from June through August. Vegetation and arthropod sampling occurred in 2021 and 2022 at 54 reaches in 7 catchments. We detected an increase in water residence time at treated reaches of 1.67 days (p=0.0069) after controlling for variation between catchments and reaches. We also found evidence for a 27% increase in total canopy cover (p=0.004) at treated reaches when compared to control reaches. We found no evidence of a difference in seasonal soil moisture, seasonal drying rate, seasonal water storage, arthropod activity density, or arthropod biomass. Our results indicate that rock restoration structures are effective in increasing soil moisture and vegetation components in mesic meadows in Southwest Montana, potentially providing a tool to restore meadows in semi-arid landscapes and build resilience against climate change.Item Ecosystem pioneers: beaver dispersal and settlement site selection in the context of habitat restoration(Montana State University - Bozeman, College of Agriculture, 2018) Ritter, Torrey Daniel; Chairperson, Graduate Committee: Lance McNewThe activities of beavers (Castor canadensis) provide a variety of benefits to stream systems by capturing and storing water and sediment, expanding riparian areas, and increasing habitat heterogeneity. Understandably, land and wildlife managers are interested in using beavers as a habitat restoration tool. However, streams targeted for restoration are often degraded and lack recent beaver activity, and therefore represent suboptimal habitat. The habitat selection process for beavers in suboptimal and unmodified habitats provides a natural analogue to beaver restoration, but the process is not well-understood. I radio-marked juvenile beavers and conducted beaver-use surveys in tributary streams of the Gallatin and Madison River drainages in southwest Montana to investigate dispersal, survival, and settlement site selection by beavers colonizing novel areas. My objective was to study beaver ecology in the context of beaver restoration to improve identification of suitable project locations. Beaver colony densities in the study area were low or average, though colony densities in suitable habitat were generally high. There was evidence of delayed dispersal, and as the density of active beaver colonies increased the probability of dispersal decreased. Radio-marked beavers that dispersed settled quickly and dispersal distances were highly variable. Most beavers settled in active colonies or other beaver-modified habitats, and colonization of unmodified stream segments was rare. My top habitat selection models indicated new settlement sites were located in stream segments characterized by low gradients, dense woody riparian vegetation close to the stream, and relatively narrow stream channels. Stream channels at new settlement sites were more variable both in cross-sectional and longitudinal depth and were more heavily influenced by secondary channels than unsettled sites. My results suggest beavers select for pre-engineered habitat over unoccupied stream segments, and in novel areas habitat conditions that facilitate stable dam construction appear most important. When choosing project locations, restoration practitioners should consider local beaver colony locations and densities to assess the potential for dispersers to reach the restoration site. Stream segments that provide dam resiliency and hiding cover should be targeted for initial restoration efforts, and pre-engineering of habitat prior to beaver occupancy may increase the probability of successful colony establishment.Item The decline of a riparian gallery forest in Devils Tower, Wyoming : causation and management techniques for restoration(Montana State University - Bozeman, College of Agriculture, 2013) Anderson, Jacob Michael; Chairperson, Graduate Committee: Clayton B. MarlowDevils Tower National Monument, Wyoming, (DT) has experienced a decline in cottonwood recruitment along the Belle Fourche River, leaving the remaining riverine forest in danger of disappearing. The National Park Service has requested information about the mechanisms behind this decline and possible management methods that could be used to restore forests to the Belle Fourche riparian corridor. Previous research has indicated that cottonwood seedlings require flood-deposited sediments and high initial groundwater for survival. A dam located 12 miles upstream of Devils Tower could be impacting the recruitment success of cottonwoods because of a decrease in seasonal flooding. If this decline is due to factors that managers have little control over, other methods should be explored to increase the success of future restoration efforts. This case study examined the physical attributes of the Devils Tower riparian area in comparison to a healthy, functioning, riparian gallery forest located on the nearby Powder River (PR) to learn the complex mechanisms that help support and sustain these healthy riparian ecosystems. Soil field tests, cottonwood surveys, and measurements of local groundwater patterns were used to compare the two sites. To determine the restoration potential of cottonwood gallery forests at Devils Tower, planting trials were conducted to provide a methodology for greater seedling survival, testing effects of residual herbicide, species planted, preliminary soil preparation including disking, herbaceous understory control, and irrigation. We observed higher groundwater and greater cottonwood age class diversity at the Powder River site, in contrast to the DT site. At DT, tree health was significantly higher (p=.0003) with shallower groundwater. Tree mortality was highest among boxelder and bur oak in sites with deepest groundwater levels. At the same time, irrigation at economically feasible levels had no significant effect on tree survival. This research suggests that site potential for cottonwood re-establishment is poor along the Belle Fourche riparian corridor due to deep groundwater tables (1.7-2.2m) and regulated flow patterns with limited sediment delivery to the floodplain environment. A successional shift resulting from regulated streamflow conditions now favors green ash over any other species.