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Articles 1 - 20 of 20
Full-Text Articles in Life Sciences
Du Undergraduate Showcase: Research, Scholarship, And Creative Works, Caitlyn Aldersea, Justin Bravo, Sam Allen, Anna Block, Connor Block, Emma Buechler, Maria De Los Angeles Bustillos, Arianna Carlson, William Christensen, Olivia Kachulis, Noah Craver, Kate Dillon, Muskan Fatima, Angel Fernandes, Emma Finch, Colleen Cassidy, Amy Fishman, Andrea Francis, Stacia Fritz, Simran Gill, Emma Gries, Rylie Hansen, Shannon Powers, Jacqueline Martinez, Zachary Harker, Ashley Hasty, Mykaela Tanino-Springsteen, Kathleen Hopps, Adelaide Kerenick, Colin Kleckner, Ci Koehring, Elijah Kruger, Braden Krumholz, Maddie Leake, Lyneé Alves, Seraphina Loukas, Yatzari Lozano Vazquez, Haley Maki, Emily Martinez, Sierra Mckinney, Mykaela Tanino-Springsteen, Audrey Mitchell, Kipling Newman, Audrey Ng, Megan Lucyshyn, Andrew Nguyen, Stevie Ostman, Casandra Pearson, Alexandra Penney, Julia Gielczynski, Tyler Ball, Anna Rini, Christina Rorres, Simon Ruland, Helayna Schafer, Emma Sellers, Sarah Schuller, Claire Shaver, Kevin Summers, Isabella Shaw, Madison Sinar, Claudia Pena, Apshara Siwakoti, Carter Sorensen, Madi Sousa, Anna Sparling, Alexandra Revier, Brandon Thierry, Dylan Tyree, Maggie Williams, Lauren Wols
Du Undergraduate Showcase: Research, Scholarship, And Creative Works, Caitlyn Aldersea, Justin Bravo, Sam Allen, Anna Block, Connor Block, Emma Buechler, Maria De Los Angeles Bustillos, Arianna Carlson, William Christensen, Olivia Kachulis, Noah Craver, Kate Dillon, Muskan Fatima, Angel Fernandes, Emma Finch, Colleen Cassidy, Amy Fishman, Andrea Francis, Stacia Fritz, Simran Gill, Emma Gries, Rylie Hansen, Shannon Powers, Jacqueline Martinez, Zachary Harker, Ashley Hasty, Mykaela Tanino-Springsteen, Kathleen Hopps, Adelaide Kerenick, Colin Kleckner, Ci Koehring, Elijah Kruger, Braden Krumholz, Maddie Leake, Lyneé Alves, Seraphina Loukas, Yatzari Lozano Vazquez, Haley Maki, Emily Martinez, Sierra Mckinney, Mykaela Tanino-Springsteen, Audrey Mitchell, Kipling Newman, Audrey Ng, Megan Lucyshyn, Andrew Nguyen, Stevie Ostman, Casandra Pearson, Alexandra Penney, Julia Gielczynski, Tyler Ball, Anna Rini, Christina Rorres, Simon Ruland, Helayna Schafer, Emma Sellers, Sarah Schuller, Claire Shaver, Kevin Summers, Isabella Shaw, Madison Sinar, Claudia Pena, Apshara Siwakoti, Carter Sorensen, Madi Sousa, Anna Sparling, Alexandra Revier, Brandon Thierry, Dylan Tyree, Maggie Williams, Lauren Wols
DU Undergraduate Research Journal Archive
DU Undergraduate Showcase: Research, Scholarship, and Creative Works
Modeling Vegetation Cover At Mount St Helens Using Highly Correlated Vegetation Indices, Sara Livingston
Modeling Vegetation Cover At Mount St Helens Using Highly Correlated Vegetation Indices, Sara Livingston
Geography and the Environment: Graduate Student Capstones
The eruption of Mount St. Helens in 1980 devastated the landscape and obliterated all ground vegetation within a 620 km2 blast zone radius. The destructive forces of the lateral blast, debris avalanche, tephra plume, and lahar flow created a complex mosaic of disturbance zones, that subsequently yielded various rates of landscape recovery. Remote sensing is an efficient method for monitoring landscape-scale changes by recording the distinct spectral reflectance of vegetation. Based on statistically significant correlations between Vegetation Indices and vegetation parameters, an empirical model can be developed for vegetation cover predictions. This capstone analysis found that NDVI holds the strongest …
Responses Of Arthropods To Fire And How Pollinators And Pollination Services Are Affected By Fire Severity, Blyssalyn V. Bieber
Responses Of Arthropods To Fire And How Pollinators And Pollination Services Are Affected By Fire Severity, Blyssalyn V. Bieber
Electronic Theses and Dissertations
Fires impact ecosystems globally and due to climate change, there are shifts in fire regimes that impact ecological communities which provide essential ecosystem services. Focusing on arthropods, fire can influence this ubiquitous animal group in various way. We performed a comprehensive meta-analysis evaluating how fires impact differing arthropod functional groups. We found that overall, fire negatively effects community level responses for most functional groups with herbivores as the only exception showing some positive effects of fire. We also studied mixed-severity fires that burned >20 years ago and compared floral visitor communities across fire severities. We implemented a pollinator exclusion experiment …
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Environmental Gradients Impact Key Leaf Traits In Riparian Trees, Amanda Malone
Electronic Theses and Dissertations
Specific leaf area (SLA) reflects a plant’s carbon investment per area and relates to generalized leaf economics spectrum growth strategies (LES). To fill gaps of knowledge about intraspecific SLA variation and why it is often inconsistent with the LES, we studied the response of two riparian tree species along the urban-rural gradient in Northeastern Colorado: an invasive, nitrogen-fixer with broad tolerances and a nitrogen-limited and shade-intolerant native. Despite these differences, the two species responded similarly, apart from the response to the urban-rural gradient, in which lower nitrogen in rural areas was associated with a more conservative strategy in the native …
Poor Acclimation To Experimental Field Drought In Subalpine Forest Tree Seedlings, Alex Goke, Patrick H. Martin
Poor Acclimation To Experimental Field Drought In Subalpine Forest Tree Seedlings, Alex Goke, Patrick H. Martin
Biological Sciences: Faculty Scholarship
The ability of tree species to acclimate and tolerate projected increases in drought frequency and intensity has fundamental implications for future forest dynamics with climate change. Inquiries to date on the drought tolerance capacities of tree species, however, have focused almost exclusively on mature trees with scant in situ work on seedlings, despite the central role that regeneration dynamics play in forest responses to changing conditions. We subjected naturally established seedlings of co-dominant subalpine conifer species (Abies lasiocarpa and Picea engelmannii) in the southern Rocky Mountains to 2 years of in situ summer precipitation exclusion, simulating summer drought …
Understanding Patterns And Functional Impacts Of An Invasive Tree And Its Biological Control In A Riparian System, Annie L. Henry
Understanding Patterns And Functional Impacts Of An Invasive Tree And Its Biological Control In A Riparian System, Annie L. Henry
Electronic Theses and Dissertations
Invasive species have become an inextricable part of the landscape, particularly in riparian plant communities, and removal is often a key component of restoration programs. Biological control (biocontrol) is a method of removal that is often both efficient and effective. However, the impact of biocontrol on target species and indirect effects from invasive species removal can be hard to predict. While monitoring the impact of invasive species removal usually involves some species-based assessment such as changes in diversity, historically dominant species or native species, these strategies do not typically provide insight into the mechanisms underlying plant community response to removal. …
The Ecological Resilience Of A Tropical Montane Pine Forest To Droughts, Fire, And Hurricane Disturbance, Daniel Erland Brugger Swann
The Ecological Resilience Of A Tropical Montane Pine Forest To Droughts, Fire, And Hurricane Disturbance, Daniel Erland Brugger Swann
Electronic Theses and Dissertations
Owing to the geographic isolation and unique climatic conditions which occur in tropical montane forests (TMFs), these systems are highly sensitive to changes in both climate and disturbance. Therefore, as ongoing climate change alters disturbance regimes – potentially facilitating multiple disturbance interactions much greater than that of isolated disturbances – TMFs may be shifted to alternate stable states. However, study of TMF resilience is essentially unknown given the lack of long-term studies in these systems. We address the resiliency of the tropical montane pine forests of the Cordillera Central, Dominican Republic using long-term climate records, remeasured vegetation data, and reconstructed …
Intellectual Property Rights In The Seed Industry: Barriers To Sustainable Agriculture, Elena A. Filatova
Intellectual Property Rights In The Seed Industry: Barriers To Sustainable Agriculture, Elena A. Filatova
Electronic Theses and Dissertations
The dynamics of the dominant industrial agriculture system restrict the seed industry’s innovative landscape, leading to significant negative consequences including an exacerbation of environmental risks which threaten global food security. This thesis explores how exclusionary intellectual property rights (IPRs) in the context of the seed industry constrict innovation, evolutionary pathways, and opportunities for the implementation of sustainable agriculture methods. To overcome these barriers, the application of an open source framework to seed innovation, specifically through the platform of the Open Source Seed Initiative, is evaluated as a tool for enhancing innovative capacities in seed development while broadening the accessibility and …
Examining Climate Change Effects On Flowering In Moss Campion, Mykaela Tanino-Springsteen, Olivia Dewitt, Anna Sher
Examining Climate Change Effects On Flowering In Moss Campion, Mykaela Tanino-Springsteen, Olivia Dewitt, Anna Sher
DU Undergraduate Research Journal Archive
Examining the variation in the collection date of herbarium specimens is a common method for studying the phenological effects of climate change on a flowering plant species. We used herbarium data to examine how warming temperatures have affected flowering time in Silene acaulis in the state of Colorado. Silene acaulis, commonly known as moss campion and cushion pink, is an alpine tundra plant. Using ordinal date of collection as a proxy for flowering date and year collected as a proxy for increasing average temperature, a linear regression test found that there was no significant relationship between increasing temperatures and …
Wood-Inhabiting Fungi Of The Eastern Ecuadorian Cloud Forest: Fungal Diversity Comparison Along An Altitudinal Gradient In The Rio Zuñac Reserve, Thane Gehring, Rosa Batalles
Wood-Inhabiting Fungi Of The Eastern Ecuadorian Cloud Forest: Fungal Diversity Comparison Along An Altitudinal Gradient In The Rio Zuñac Reserve, Thane Gehring, Rosa Batalles
DU Undergraduate Research Journal Archive
Wood-inhabiting fungi are responsible for the degradation of dead wood, playing a role in nutrient cycling and nutrient transport making them indispensable to their ecosystem’s health. Fungi are generally understudied, specifically in the tropics despite its proven hotspot in diversity and the importance of conservation. Wood-inhabiting fungi were investigated in the eastern Andean montane cloud forest of Ecuador to determine the biodiversity, distribution, and relation to an altitudinal gradient. Along multiple ridges of EcoMinga’s Rio Zuñac reserve, 13 20x20 meter (0.1-hectare) quadrants between the altitudes of 1300 to 2000 meters were sampled for wood-inhabiting fungi. A total of 175 samples …
Subalpine Forest Tree Seedling Response To Drought, Alex Goke
Subalpine Forest Tree Seedling Response To Drought, Alex Goke
Electronic Theses and Dissertations
Knowledge of tree species’ ability to tolerate drought is necessary to anticipate future forest dynamics with climate change, especially at the seedling stage given their role in shaping forest structure. We used precipitation reduction shelters to mimic drought for subalpine conifer seedlings (A. lasiocarpa and P. engelmannii) in the Rocky Mountains and compared survivorship and morphological and physiological responses to assess relative degrees of drought tolerance. We detected no significant investment in morphological tolerance traits (e.g. root biomass, leaf:stem area ratio) but substantial reductions in net photosynthesis. While shading partially ameliorated drought effects when precipitation reduction was moderate, …
Terracing, Land Management And Agricultural Soils In The Andagua Valley Of The Southern Peruvian Andes, Blaise Murphy
Terracing, Land Management And Agricultural Soils In The Andagua Valley Of The Southern Peruvian Andes, Blaise Murphy
Electronic Theses and Dissertations
Demographic, socio-political and climatic changes can drastically alter agricultural land management practices, affecting the availability of agriculturally relevant nutrients in the soil. This project investigates the use, reconstruction and abandonment of agricultural terraces and the implications these conditions have on agricultural soil properties of the Andagua Valley in the Western Cordillera of the Southern Peruvian Andes. During the 2016 summer field season, topsoil samples were collected from cultivated and abandoned agricultural terraces between 3229m and 3688m a. s. l. with a range of aspects and ages. Collaboration with a team of archaeologists and anthropologists gave insight into the local and …
Exploring Historical Coffee And Climate Relations In Southern Guatemala: An Integration Of Tree Ring Analysis And Remote Sensing Data, Diego Pons
Electronic Theses and Dissertations
This dissertation makes use of a physical geography perspective to examine the relationship between agriculture and climate in Guatemala using dendrochronology. I examined the potential of high-resolution climate proxy data from dendrochronology to help fill in the gaps of past climate information to better understand the natural and anthropogenic variability of precipitation which, in turn, can inform Guatemala’s agriculture sector. This research has demonstrated successful cross-dating and climate sensitivity of Abies guatemalensis in the Pacific slope of Guatemala. Based on this, I have produced a 124-year record of mean precipitation from June-July-August. The mean precipitation from June-July-August at this site …
The Ecology And Evolution Of Rare, Soil Specialist Astragalus Plants In The Arid Western U.S., Joseph M. Statwick
The Ecology And Evolution Of Rare, Soil Specialist Astragalus Plants In The Arid Western U.S., Joseph M. Statwick
Electronic Theses and Dissertations
Organisms that specialize in uncommon habitats are, by their very nature, inherently uncommon. Specialization has its advantages, namely reduced competition and predation, but it also incurs costs. Specialists often have small population sizes, narrow ranges, and fragmented habitat, all of which engender negative consequences on an evolutionary timescale. Herein, I examine benefits and costs of specialization in selenium-hyperaccumulating plants in the genus Astragalus (Fabaceae). These plants are disproportionately likely to be rare and of conservation concern. Thus, I optimized germination pretreatments for Astragalus species such that seed loss can be minimized during ex situ cultivation, and found that physical scarification …
Long-Term Changes In Four Plant Communities Along An Elevational Gradient In The Front Range Of Colorado, Gregory J. Sproull
Long-Term Changes In Four Plant Communities Along An Elevational Gradient In The Front Range Of Colorado, Gregory J. Sproull
Electronic Theses and Dissertations
We surveyed four plant communities along an elevational gradient in the Front Range of the Colorado Rocky Mountains for long-term overstory and understory changes. Our results were compared to those found in 1981 and 1996. We evaluated changes in succession, elevational species migration and range expansion, community diversity, and composition. We related temporal floristic shifts to prior literature on disturbance history at each site. Over time, all communities changed significantly, though in different manners. This analysis shows that plant communities are changing in dynamic and idiosyncratic ways that correspond to individualistic distribution shifts. Moreover, we exhibit the necessity of comprehensively …
Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer
Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer
Electronic Theses and Dissertations
Removal of Tamarix spp. (a.k.a. tamarisk, saltcedar, Athel) invasion is often involved in restoration of Western, riparian habitat; however monitoring of vegetation after removal is often neglected and thus opportunity for adaptive management lost. To address this need, I have conducted three and half years of monitoring vegetation response after invasive Tamarix removal in twenty-five sites on the East and Western Colorado, starting fall 2009. I am also comparing six different methodologies: Point intercept, line transect, nearest neighbor, meter-square quadrats, nested Whittaker plots, and densitometer with the objective of developing monitoring protocols that can be used by …
Native Grass And Forb Establishment In Post-Agricultural Soil, Courtney D. Hall
Native Grass And Forb Establishment In Post-Agricultural Soil, Courtney D. Hall
Electronic Theses and Dissertations
Restoration of degraded and abandoned agricultural land in arid and semiarid climates is a global problem. The erratic patterns of precipitation these lands experience makes restoration of a plant community difficult. Application of supplemental irrigation and inoculation with arbuscular mycorrhizal fungi (AMF) are two restoration techniques that have been suggested to overcome deficits in natural precipitation. The effects and the interactions of irrigation and seeding date on the ground cover of intended species and unintended exotic species were tested in a post-agricultural restoration experiment in south-central Colorado, USA. The greatest ground cover of intended species and lowest ground cover of …
Memory Access Patterns For Cellular Automata Using Gpgpus, James Michael Balasalle
Memory Access Patterns For Cellular Automata Using Gpgpus, James Michael Balasalle
Electronic Theses and Dissertations
Today's graphical processing units have hundreds of individual processing cores that can be used for general purpose computation of mathematical and scientific problems. Due to their hardware architecture, these devices are especially effective when solving problems that exhibit a high degree of spatial locality. Cellular automata use small, local neighborhoods to determine successive states of individual elements and therefore, provide an excellent opportunity for the application of general purpose GPU computing. However, the GPU presents a challenging environment because it lacks many of the features of traditional CPUs, such as automatic, on-chip caching of data. To fully realize the potential …
Greening The Green Revolution: Moving Beyond Chemicals To Sustainable Agricultural Practices, Elizabeth G. Crawley
Greening The Green Revolution: Moving Beyond Chemicals To Sustainable Agricultural Practices, Elizabeth G. Crawley
Electronic Theses and Dissertations
Agriculture has dominated the economy of many developing countries for centuries, which has led to development policies that center on agricultural development. An obvious approach to improved production is to decrease agricultural losses in the fields and increase efficiency to markets. This study focuses on the developmental role of pesticides and chemical fertilizers on non-traditional agricultural export farming and the adoption of IPM techniques. With farmers in the Comayagua Valley of Honduras, an Asian vegetable production center for the country, as the study population, the costs and benefits of planting oriental vegetables was examined. Statistical analysis was used to examine …
Impacts Of Tamarisk Biocontrol (Diorhabda Elongata) On The Trophic Dynamics Of Terrestrial Insects In Monotypic Tamarisk Stands, Stephanie Michelle Carroll Strudley
Impacts Of Tamarisk Biocontrol (Diorhabda Elongata) On The Trophic Dynamics Of Terrestrial Insects In Monotypic Tamarisk Stands, Stephanie Michelle Carroll Strudley
Electronic Theses and Dissertations
Combating tamarisk (Tamarix spp.), an exotic tree species that has invaded 1-1.6 million hectares of riparian land in the Midwestern United States, with the introduced leaf beetle Diorhabda elongata provides an opportunity to evaluate how the trophic spectra of terrestrial insects respond to a herbivorous biocontrol. To evaluate this restoration approach and the interaction biocontrol may have with terrestrial insect populations, I quantified trophic unit richness and abundance and common family abundance of resident insect populations while also measuring biocontrol abundance and status during the previous season (present or not present). These measurements were taken four times throughout one …