Browsing by Author "Jarnevich, Catherine, committee member"
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Item Open Access Characterizing forest biomass and the impacts of bark beetles and forest management in the southern Rocky Mountains, USA(Colorado State University. Libraries, 2020) Vorster, Anthony Grant, author; Evangelista, Paul, advisor; Paustian, Keith, committee member; Ex, Seth, committee member; Jarnevich, Catherine, committee memberTo view the abstract, please see the full text of the document.Item Open Access Distribution and economic analysis of Prosopis juliflora in Ethiopia(Colorado State University. Libraries, 2015) Wakie, Tewodros T., author; Laituri, Melinda, advisor; Evangelista, Paul, advisor; Hoag, Dana, committee member; Jarnevich, Catherine, committee memberInvasive species are one of the drivers of biological and socio-economic changes around the world. Over the past 30-40 years, the non-native Prosopis juliflora plant has emerged as a major invader of the arid and semi-arid regions of Ethiopia. Information on its distribution, impact, use and management is highly needed to contain and prevent the spread of this highly invasive plant. In the first study, I used a correlative modeling framework to track and map the current and potential distribution of P. juliflora in Afar, north-eastern Ethiopia. Specifically, I used time-series of Moderate Resolution Imaging Specrtoradiometer (MODIS) satellite imagery, 143 species-occurrence records and the Maxent modeling technique to map its current distribution. I then used topo-climatic predictors, species-occurrence records and the Maxent software to map its forecasted distribution. I found that the current extent of P. juliflora invasion in the Afar region is approximately 3,605 Km2, while its predicted distribution is approximately 5,024 Km2. My findings demonstrates that MODIS vegetation indices and species-occurrence points can be used with Maxent modeling software to map the current distribution of P. juliflora, while topo-climatic variables are good predictors of its potential habitat in Ethiopia. In the second study, I used a participatory research framework to map P. juliflora over a fine geographic scale, and to identify the major resource related problems in the region. I learned about the introduction history, spread, impacts, uses and traditional management practices of P. juliflora in Afar by interviewing 108 pastoralists and agro-pastoralists. Additionally, I detected the land-cover categories most affected by P. juliflora invasion by superimposing community produced maps on ancillary land-cover layers, and performing overlay analysis. Prosopis juliflora has highly invaded grasslands and open areas in Afar. The species displaces useful native grass and forage species, which are important for sustaining the region's wildlife and livestock resources. In addition to threats from invasive species, Afar people face conflicts from neighboring Issa ethnic groups, and land-grabs from the central government and foreign investors. The findings demonstrates that participatory mapping methods are suitable for mapping species distribution, detecting land-cover changes, and managing invasive plants. High invasive species control costs have swayed most developing countries to adopt cost effective P. juliflora eradication and utilization practices. However, the effectiveness and economic viability of these new approaches have not been thoroughly tested. In the third study, I used an economic analysis framework to assess the economic feasibility of selected P. juliflora eradication and utilization methods that are practiced in southern Afar. The dominant P. juliflora eradication option was to convert infested lands into irrigated farms, while the preferred utilization options were to make animal fodder from P. juliflora seed pods, and to produce charcoal from P. juliflora wood. I interviewed 19 enterprise owners (i.e., farmers, flour producers and charcoal makers) and collected primary data on prices, yields, costs and revenues. I assessed the economic feasibility of the selected methods by performing enterprise, profitability, sensitivity and risk analyses over 10 years and an interest rate of 10% per year. Converting P. juliflora infested lands into irrigated agriculture is a profitable and risky P. juliflora eradication approach. Charcoal making is a moderately profitable and less risky utilization approach, while flour production is a risky and an un-profitable utilization approach. Introducing new changes in the production and management steps of flour production may be needed to make flour enterprises profitable. My overall economic analysis suggests that control through utilization may be one of the effective and economically viable P. juliflora management strategies currently accessible to Ethiopia. I generated reliable information on the distribution and impacts of P. juliflora in Afar by employing a wide variety of scientific approaches. My results can guide local level P. juliflora utilization and control efforts in Afar, while my methodologies can be replicated for managing invasive plants in other developing countries.Item Open Access Influences of ongoing and projected environmental change in range margin Sequoia sempervirens (coast redwood) forests(Colorado State University. Libraries, 2021) Woodward, Brian David, author; Evangelista, Paul, advisor; Ex, Seth, committee member; Jarnevich, Catherine, committee member; Romme, William, committee memberTo view the abstract, please see the full text of the document.Item Embargo Species distribution models for and policy approaches to invasive plant ecology and management(Colorado State University. Libraries, 2024) Teich, Nathan Benjamin, author; Brown, Cynthia S., advisor; Jarnevich, Catherine, committee member; Pearse, Ian, committee member; Evangelista, Paul, committee memberThe ability of abundance-based Species Distribution Models (SDMs) to predict where invasive plants can be abundant, and to what degree, is a powerful research and management tool. Often, invasive plant abundance-based SDMs are created using similar inputs and approaches as occurrence SDMs. However, invasive plant ecology literature suggests that the factors found to control invasive plant abundance are more diverse and contextual, and therefore not entirely interchangeable with factors that control invasive plant occurrence. To ensure invasive plant abundance-based SDMs are leveraging the robust body of knowledge, this paper aims to highlight and summarize the ecological factors underpinning invasive plant abundance and reviews how those factors can be represented within abundance-based SDMs. I find that while the inclusion of invasive plant abundance governing factors often improves abundance-based SDM performance, certain governing factors are ubiquitously represented while others are less commonly accounted for in model creation despite their ecological importance. Barriers to incorporating invasive plant abundance governing factors into abundance-based SDMs often include data limitations or methodological uncertainty. Finally, we provide future research directions that would help address certain barriers and improve our ability to integrate abundance governing factors into SDMs. Invasive plants, when they become dominant components of a plant community, threaten native species and ecosystem processes. Abundance-based SDMs are gaining traction as a geospatial tool to predict where invasive plants can become abundant and have negative impacts. Biotic interactions influence invasive plant abundance locally but are often not included within the abundance-based SDM creation process. At present, it is unknown to what degree local-scale biotic interactions with other plant species determine locations where invasive plant species can become abundant. Using data from large-scale abundance observations of the invasive plant cheatgrass (Bromus tectorum) paired with data from plant communities in the western United States, we quantified the degree to which biotic interactions explain where cheatgrass is abundant beyond what would be anticipated from an abundance-based SDM created with abiotic and landscape context predictors alone. To this end, we fit Generalized Linear Models (GLMs) for different categories of cheatgrass abundance and used the predicted suitability SDM outputs alongside biotic variables, representing known competitive and facilitative interactions, to determine if including biotic interactions improved a model's explanatory power. The addition of biotic variables marginally improved GLMs for low (5-25%) and medium (25+-50%) cheatgrass abundance but displayed greater improved performance for high (50+%) cheatgrass abundance. Most notable amongst the specific biotic variables was the cover of perennial graminoid cover, representing known competitors of cheatgrass, which interacted with SDM environmental suitability to strongly reduce the probability of high cheatgrass abundance. These findings suggest that considering biotic interactions alongside SDM predicted suitability may indeed improve our ability to predict abundance locations of invasive plant species, but potentially only in specific contexts such as where that species can already achieve high abundance. Invasive plants cost the US billions of dollars each year due to ecological and economic impacts as well as management costs. One of the most common pathways of introduction and spread of invasive plants is through ornamental plant sales. While solutions such as regulations and voluntary self-bans have been implemented in some instances to mitigate this problem, widespread adoption has not occurred. As such, new alternatives should be explored. Opt-in labeling programs are commonly used throughout the agricultural industry to better inform customers about the products they are purchasing. An opt-in labeling program that consists of a partnership between retailers and governments or non-profit organizations could help reduce the spread of invasive plants by influencing customer behavior. This approach would be less costly to retailers than regulations, create new invasive plant prevention opportunities for governments and non-profits, and better inform consumers about specific invasive plant species.