Theses and Dissertations at Montana State University (MSU)
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Item Forecasting vertebrate species habitat suitability and ecoregion types under future climate change scenarios using Species Distribution Modeling (SDM)(Montana State University - Bozeman, College of Letters & Science, 2023) Veneros Guevara, Jaris Emmanuel; Chairperson, Graduate Committee: Andrew J. Hansen; This is a manuscript style paper that includes co-authored chapters.Peru, Ecuador, and Colombia have identified a total of 23 threatened species, including mammals, birds, and plants, which are also a part of their reports for SDG 15. These countries are keen to monitor the risk of extinction of these species and ensure their protection. As part of the Life on Land Project, we aim to assist these countries in approximating the IUCN Red List index using species occurrence data, climatic data, and variables such as Human Footprint (HFP) in different climate change scenario. To achieve this, we conducted a general review of climate drivers and climate change for the three countries and explored climate data to estimate the variation of temperature (°C) and annual precipitation (mm) change under current climate conditions and in RCPs-2050 climate change scenarios (2.6, 4.5, and 8.5). Our results indicated that the average annual temperature for 2050, using a baseline of 1970-2000, is expected to increase by over 1 °C in some areas and over 4 °C in others. For annual precipitation, an increase is also predicted, although few global circulation models show a reduction. We also conducted a median comparison to see the differences between the baseline and the RCPs in 2050, indicating that the medians are different. Density plots were used to illustrate the shift to the right for the temperature case, confirming the anticipated temperature increase by 2050 in the three RCPs. Finally, we used the R package (SDM) to estimate habitat suitability probability for the spectacled bear and the paramo ecoregion. Our findings indicated that climate change impacts their areas with high probability of occurrence to a great extent, and their habitats are also affected by HFP. These methods for exploring climate data and assessing habitat suitability are replicable and can be used with other environmental variables.Item Irrigation ditches as novel intermittent stream networks that provide energetic subsidies to terrestrial ecosystems via aquatic insect emergence(Montana State University - Bozeman, College of Letters & Science, 2024) Heili, Nathaniel Maxwell; Chairperson, Graduate Committee: Wyatt F. CrossNon-perennial streams dominate fluvial networks, comprising over half of lotic ecosystems globally. Although little attention has been paid to these systems relative to those that are perennial, perhaps even less is known about the ecology of artificial intermittent streams. In irrigated river valleys, ditches comprise a substantial proportion of surface water networks, but little is known about their relative contributions to lotic habitat, freshwater biodiversity, and ecosystem processes. Because ditches are abundant and permeate arid floodplains, they create new opportunities for cross-ecosystem subsidies through emergence of adult aquatic insects. Here, we mapped the extent of an irrigation ditch network relative to natural surface waters in the Gallatin River Valley, Montana, USA. We also quantified the magnitude, composition, and phenology of aquatic insect emergence in ditches throughout a full irrigation season and compare emergence to nearby natural streams in the valley. We found that non-perennial streams, both natural and artificial, dominated the surface-water network, representing over 70% of total length. Irrigation ditches also constituted 37% and 23% of total length and surface area of all waterbodies in the valley, respectively. Insect emergence production from ditches averaged 32.0 mg m -2 d -1 and exceeded fluxes from nearby natural streams, which contained more classically sensitive taxa (i.e., Ephemeroptera, Trichoptera, and Plecoptera). Ditches varied in water temperature, substrate size, and flow permanence, leading to distinct emergence timing, species composition, and magnitudes of biomass flux. One of the study ditches dried early because of more 'junior' water rights, but this ditch provided the largest emergence subsidy, including a pulse of dipteran emergence at the onset of flow cessation. Annual production from intermittent ditches was ~6 g m -2 y -1 and was comparable to estimates from natural perennial streams. Although our study focused on one river valley of the western US, results suggest that these ecosystems contribute broadly to lotic habitat, heterogeneity, and cross-ecosystem subsidies via aquatic insect emergence. Given increasing demand for water and changes to flow regimes and water management driven by climate change, additional study is needed on these novel and underappreciated artificial ecosystems.Item Pollinator conservation and restoration in semi-natural ecosystems(Montana State University - Bozeman, College of Letters & Science, 2022) Glenny, William Robb; Chairperson, Graduate Committee: Laura Burkle; This is a manuscript style paper that includes co-authored chapters.Semi-natural ecosystems are areas with biological and physical characteristics that resemble natural ecosystems but are also affected by anthropogenic disturbances. Semi-natural ecosystems are also areas with high insect pollinator diversity. Land management actions within semi-natural ecosystems may therefore be important to counteract future declines of insect pollinators. However, current restoration strategies for insect pollinator communities are based on evidence from agricultural ecosystems, which have frequent human interventions to ensure plant success, neglect the importance of nesting materials, and primarily benefit generalist species. To inform management actions for the conservation and restoration of insect pollinators in semi- natural ecosystems, I (1) synthesized the current understanding of the effects of common land management actions on insect pollinators on public lands in the US, (2) identified habitat characteristics which structure the taxonomic and functional diversity of bee communities, (3) evaluated the strength of influence of mechanisms associated with diet breadth across groups of bee species and (4) designed a conceptual model which can be used to select flowering plant species to provide food resources for bee communities in semi-natural ecosystems. Management actions that increase the abundance of floral and nesting resources to support bee species from different functional groups are required to conserve and restore insect pollinator communities in semi-natural ecosystems. I found that (1) management actions have positive, neutral, and negative effects on insect pollinators, but research trends vary depending on the taxon and habitat type, (2) the taxonomic and functional diversity of bee communities are structured by the abundance of both floral and nesting resources, (3) patterns of abundance across space and time have a more positive effect on the diet breadth of bumble bee species compared to non- bumble bee species, and (4) wildflower species that receive a high visitation rate and richness, occupy functionally important positions within bee-flower interaction networks, and are spatially and temporally widespread are important to provide bee communities with food resources in semi-natural ecosystems. These wildflower species may be particularly important to include within seed mixes to revegetate semi-natural ecosystems and provide food resources for insect pollinators.