Plant Biology Commons^™

Nitrogen Availability In Dune Systems And Its Effect On Root Fungal Endophyte Communities., Haley E. Sage

College of Arts & Sciences Senior Theses

As global change persists, changes in resource availability can influence plant-microbe interactions. To understand how resource availability can influence these interactions and species diversity, I focused this research on how varying nitrogen (N) levels affect root endophyte communities in the plant species Ammophila breviligulata, an ecosystem engineer in the dune system. I analyzed the relationship between nitrogen addition and microbial community composition across 60 plots treated with three nitrogen addition levels (control, low, and high) in a long-term experimental field site in the Lake Michigan dunes. I identified Ammophila breviligulata's root endophyte community after creating a culture collection and …

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 …

Getting To The Root Cause: The Genetic Underpinnings Of Root System Architecture And Rhizodeposition In Sorghum, Farren Smith

Graduate Theses, Dissertations, and Problem Reports (ETD)

Plants are some of the most diverse organisms on earth, consisting of more than 350,000 different species. To understand the underlying processes that contributed to plant diversification, it is fundamental to identify the genetic and genomic components that facilitated various adaptations over evolutionary history. Most studies to date have focused on the underlying controls of above-ground traits such as grain and vegetation; however, little is known about the “hidden half” of plants. Root systems comprise half of the total plant structure and provide vital functions such as anchorage, resource acquisition, and storage of energy reserves. The execution of these key …

Changes In Plant Community Composition, Structure, And Function In Response To Permafrost Thaw, Katherine Standen

Theses and Dissertations (Comprehensive)

Air temperature is increasing at three or more times the global average in high latitudes, causing widespread permafrost thaw across the boreal biome. Since the boreal biome stores 30-40% of global terrestrial carbon (C), of which about 30-45% is found in permafrost soils, this temperature increase could cause a large efflux of C to the atmosphere. Climate warming and permafrost thaw are also expected to alter plant community composition and productivity and, given the link between plant functional traits and ecosystem C fluxes, may alter overall ecosystem function. Across the boreal biome of western Canada, we know surprisingly little about …

Examining The Invasion Of A Bush Honeysuckle Using Climate Analysis, Andrew Palmer

Biological Sciences Undergraduate Honors Theses

Within the study of invasive plants, particular importance is placed on elucidating the mechanisms by which these plants proliferate and dominate within their introduced ranges. Several theories have been advanced to explain these invasions, each with different implications for the predicted range of invasive plants. Recent studies have provided support for the application of several invasion theories to Lonicera maackii, or what is more commonly referred to as bush honeysuckle. This species provides a unique opportunity to examine the efficacy of these theories in explaining the range expansion of invasive plants. L. maackii is endemic to eastern Asia, but …

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 Mechanisms And Consequences Of Shrub Encroachment On The Virginia Barrier Islands, Lauren K. Wood

Theses and Dissertations

Shrub encroachment is a global phenomenon driven by direct and indirect anthropogenic influence which alters plant communities and ecosystem function. Many studies have investigated drivers and consequences of woody plant establishment, but mesic landscapes are underrepresented in the literature. My objective was to assess the mechanisms of Morella cerifera encroachment into coastal mesic grassland, the potential for self-reinforcement, and consequences on community composition, nutrients, and landscape productivity. I studied temperature and water microclimate modification by Morella cerifera presence and removal to understand ecosystem engineering and community composition changes. Additionally, I examined the influence of shrubs on surrounding grassland species traits …

Characterizing Patterns In Texas Gulf Coast Beach Dune Plant Species Composition, Cody Foster

Electronic Theses and Dissertations

Regional vegetation patterns of Texas beach plant communities were analyzed using cluster analysis, ANOSIM, SIMPER, NMDS, and ISA for fives zones representing the foredune complex of twenty Gulf Coast beaches. ANOVA revealed that zones differ in terms of percent bare sand, percent vegetative cover, and species richness. Cluster Analysis, ANOSIM, and SIMPER results indicate that Texas beaches can be divided into northern and southern regions based on differences in species composition of plant communities. Indicator Species Analysis (ISA) indicates that northern beaches are characterized by the presence of Rayjacksonia phyllocephala, Ambrosia Strophostyles, Ambrosia psilostachya, and Panicum amarum …

Leaf Traits And Performance Vary With Plant Age And Water Availability In Artemisia Californica, Jennifer L. Funk, Julie E. Larson, Gregory Vose

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background and aims
Leaf functional traits are strongly tied to growth strategies and ecological processes across species, but few efforts have linked intraspecific trait variation to performance across ontogenetic and environmental gradients. Plants are believed to shift towards more resource-conservative traits in stressful environments and as they age. However, uncertainty in how intraspecific trait variation aligns with plant age and performance in the context of environmental variation may limit our ability to use traits to infer ecological processes at larger scales.

Methods
We measured leaf physiological and morphological traits, canopy volume, and flowering effort for Artemisia californica (California sagebrush), a …

Molecular Differentiation Of Astragalus Species And Varieties From The Western United States: The Chloroplast Dna Bridge Between Evolution And Molecular Systematics, Marwa Neyaz, Daniel Cook, Rebecca Creamer

Poisonous Plant Research (PPR)

Locoweeds are the most widespread poisonous plant problem in the world and have been reported in the Western United States since the 1800s, causing tremendous losses in livestock. Consumption of locoweeds by grazing animals stimulates the neurological disease, locoism, characterized by weight loss, ataxia, and lack of muscular coordination. The name locoweed is used for Astragalus and Oxytropis species known to contain swainsonine, the toxic principle produced by the plant endophytic fungus Undifilum. Astragalus includes 2,500-3,000 species and many varieties that have almost identical morphological characteristics that overlap among species, leading to improper identification. Therefore, the aim of this study …

Eelgrass Health Survey And Results, Nicholas B. Anderson, Catherine M. Ashcraft, Dante D. Torio, Frederick T. Short

Natural Resources & the Environment

Researchers at the University of New Hampshire designed, tested, and conducted an eelgrass health survey. The primary goal of the survey was to collect health ratings from respondents who had viewed pre-selected images of eelgrass representing a wide range of health conditions. Survey results were used as a calibration and validation to a novel eelgrass health index developed using video-monitoring. Two secondary goals of this this survey were the identification of plant-specific and environmental characteristics important to respondents and the introduction of the new eelgrass health index. This published dataset includes de-identified survey respondent background and demographic data, the survey …

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, …

Impacts Of Rock Climbing On Lichen And Bryophyte Cliff Communities In The Arid West, Giovanna M. Bishop

2020 Symposium Posters

Lichens and bryophytes make up the majority of the diversity and cover in cliff systems around the world. Recently, with the rapid rise of rock climbing, there are concerns rock climbers are negatively impacting cliff communities. My study will compare climbed and unclimbed granite cliffs to better understand the impacts of rock climbing on lichen and bryophyte diversity and cover in eastern Washington. The objectives of this study are to assess the impacts of rock climbing on lichen and bryophyte cliff community diversity and cover and improve route development and cliff management practices for lichens and bryophytes. This study will …

The Effects Of Woody Vegetation Encroachment And Removal Within A Coastal Fen, Joseph Saler

Cal Poly Humboldt theses and projects

Early successional wetland habitat is being lost in temperate regions worldwide as a result of changes in disturbance regimes that allow for the establishment and dominance of woody species. In particular, this phenomenon is pronounced in fens, which harbor high numbers of rare herbaceous species that require early successional habitat. I investigated the relationship between woody vegetation encroachment and herbaceous species diversity within a Northern California coastal fen that has been undergoing encroachment by woody vegetation for ca. 80 years by recording species richness and cover data from 338 permanent plots throughout the fen. I also investigated the effect of …

Quantifying Pollen Traits To Build A Mathematical Model Of Pollen Competition - A Mathematician's Perspective, Montana Ferita, Julie Fucarino, Alex Capaldi, Charlotte Beckford

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Quantifying Pollen Traits To Build A Mathematical Model Of Pollen Competition - A Biologist's Perspective, Rob Swanson, Alex Capaldi

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Diffuse Light And Wetting Differentially Affect Tropical Tree Leaf Photosynthesis, Z. Carter Berry, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

‐Most ecosystems experience frequent cloud cover resulting in light that is predominantly diffuse rather than direct. Moreover, these cloudy conditions are often accompanied by rain that results in wet leaf surfaces. Despite this, our understanding of photosynthesis is built upon measurements made on dry leaves experiencing direct light.

‐Using a modified gas exchange setup, we measured the effects of diffuse light and leaf wetting on photosynthesis in canopy species from a tropical montane cloud forest.

‐We demonstrate significant variation in species‐level response to light quality independent of light intensity. Some species demonstrated 100% higher rates of photosynthesis in diffuse light …

Pollinator Visitation Frequency Associated With Native And Non-Native Plants In A Mid-Atlantic Piedmont (Usa) Urban Garden, Nicholas J. Ruppel, Saunders M. Riley, Ellis D. Mumford, Barbara L. Swedo

Virginia Journal of Science

The recent focus on the importance of native plants and their pollinators has highlighted the critical role of local species in their natural environment. As urban encroachment, climate change, and invasive species continues to threaten native habitats, it is increasingly important to promote the use of local green spaces as refugia for native plants and their pollinators. The aim of this project, therefore, was to identify and assess the visitation frequency of insect pollinators associated with an urban setting within the Piedmont region of Virginia, and compare their association with native versus closely-related but non-native summer-flowering plants. Several modes of …

Fire And Road Disturbance Impacts On Forest Plant Species And Seed Rain In Table Mountain Fire Arai, Kittitas County, Washington, Jonathan A. Betz

All Master's Theses

Forest communities are in a constant state of change. Disturbance events can alter the physical landscape and create conditions favorable to some species while negatively impacting others. Fire has been a natural, reoccurring source of disturbance in Pacific Northwest forests. Over the past centuries the fire paradigm has changed in favor of fire suppression. Forest roads permit access provide greater access but further fracture forest community’s continuity. The 2012 Table Mountain Fire and road influence have altered the plant community’s seed rain and vegetation. This study measured dispersed seeds and understory vegetation cover as functions of roads and fire intensity. …

Competition Or Facilitation: Examination Of Interactions Between Endangered Sida Hermaphrodita And Invasive Phragmites Australis, Samantha N. Mulholland

Theses and Dissertations (Comprehensive)

Virginia Mallow (Sida hermaphrodita) is a perennial herb of the Malvaceae family that is native to riparian habitats in northeastern North America. Throughout most of its geographical distribution however, it is considered threatened and only two populations are known from Canada. The biology and ecology of S. hermaphrodita are still poorly understood and although few studies have been performed to determine the factors that contribute to the species rarity, it is considered threatened potentially due to the loss of habitat caused by exotic European Common reed (Phragmites australis subsp. australis) invasion. Allelopathic and phytotoxic conditioning of …

The Role Of Ferric Reduction Oxidases In Plant Anti-Herbivore Defense., Virginia C. Nunamaker

College of Arts & Sciences Senior Theses

Iron is an essential element required for plants to carry out metabolic functions such as photosynthesis, heme biosynthesis, and chlorophyll biosynthesis. Within Arabidopsis thaliana, eight ferric reduction oxidase (FRO) genes function in iron uptake and homeostasis with tissue specific expression. However, little else is known regarding the biological role of FROs. Recent studies identify the FRO gene family as particularly responsive to the green leaf plant derived volatile (GLV) cis-3-hexenyl acetate (z3HAC). Since z3HAC acts as a wound signal and cues unaffected parts of the plant to prime defenses prior to herbivory, an increase in FRO activity in response …

Factors Affecting The Regrowth Of Ilex Glabra In A Routinely Burned Longleaf Forest, Jaybus Price

Master's Theses

This study examines the effects of historical management by use of prescribed fire on Ilex glabra stems/m² and factors affecting the regrowth of I. glabra after a prescribed burn to gain beneficial knowledge for management purposes. Environmental factors and morphological parameters of I. glabra were sampled before and after a prescribed burn of the Longleaf Trace Nature Preserve in September 2016. The study site is located in Lamar County, Mississippi, just west of Hattiesburg, MS. Stem densities of I. glabra were collected once before the prescribed burn and twice after the prescribed burn at 2 month and 9 month …

What Drives Species Richness In Colorado's Alpine Tundra, Michael Kintgen

Regis University Student Publications (comprehensive collection)

Despite years of research, drivers of vascular plant species richness in Colorado’s alpine tundra habitats are largely unknown. Factors such as slope aspect, Pleistocene glaciation, nutrient levels, latitude and longitude, snow depth, and disturbance have been studied. Despite this research, few patterns have emerged. Research in Colorado has been conducted on a few well studied mountains. Aridity is one factor that has not been well studied but shows promise in explaining species richness. In Patagonia and the Swiss Alps, increasing aridity correlates with higher species richness. Here, a full species assessment was conducted on nine mountains previously under researched or …

Evolution Of Floral Morphology And Symmetry In The Miconieae (Melastomataceae), Maria Gavrutenko

Dissertations and Theses

Analyses of evolution of floral morphology and symmetry broaden our understanding of the drivers of angiosperm diversification. Integrated within a flower, labile floral characters produce different phenotypes that promote variable interactions with pollinators. Thus, investigation of floral evolution may help infer potential historic transitions in pollinator modes and ecological pressures that generated present diversity. This study aims to explore morphological evolution of flowers in Miconieae, a species-rich Neotropical tribe within family Melastomataceae. Despite a constrained floral plan, Melastomataceae manage to achieve a variety of floral traits appealing to diverse pollinator types, with majority of the species requiring specialized “buzz pollination” …

Investigating The Ecology Of A Rare Species On St. John, Usvi: Reintroducing Solanum Conocarpum In Light Of Climate Change, Cecilia Rogers

Senior Honors Projects, 2010-2019

Approximately two thirds of St. John is National Park territory. However, the land has been threatened with tourism and development, greatly impacting island biodiversity. One species that may become extinct due to this degradation is Solanum conocarpum. S. conocarpum is a rare shrub, endemic to the dry tropical forests of St. John, USVI. This plant is a species of conservation concern and is one of very few native and endemic plants on this island. Very little is known about the ecology and reproduction of S. conocarpum. Most plants are found on the southern half of the island. Recent observations …

Natural And Anthropogenic Drivers Of Tree Evolutionary Dynamics, Brandon M. Lind

Theses and Dissertations

Species of trees inhabit diverse and heterogeneous environments, and often play important ecological roles in such communities. As a result of their vast ecological breadth, trees have become adapted to various environmental pressures. In this dissertation I examine various environmental factors that drive evolutionary dynamics in threePinusspecies in California and Nevada, USA. In chapter two, I assess the role of management influence of thinning, fire, and their interaction on fine-scale gene flow within fire-suppressed populations of Pinus lambertiana, a historically dominant and ecologically important member of mixed-conifer forests of the Sierra Nevada, California. Here, I find evidence …

The Three Creeks Allotment Consolidation: Changing Western Federal Grazing Paradigms, Taylor Payne

Human–Wildlife Interactions

The federal government owns approximately 47% of all land in the western United States. In the state of Utah, about 64% of the land base is managed by the federal Bureau of Land Management (BLM) and the U.S. Forest Service (USFS). The government has historically issued permits to owners of private lands to allow the owners to graze their livestock on public lands. The permits (allotments) are generally of 10-year duration and allow for an annual season of use. In some cases, continued and repeated historical annual grazing practices may not be ideal for permit holders and their communities nor …

Survey Of Trap Contents Of Four Species Of Bladderworts (Utricularia) From Harlow Lake In Marquette, Mi., Jenna Happach

Conspectus Borealis

No abstract provided.

Size-Dependent Patterns Of Reproductive Investment In The North American Invasive Plant Species Triadica Sebifera (L.) Small (Euphorbiaceae), Courtney H. Babin

LSU New Orleans Theses and Dissertations

Knowledge of sex allocation trade-offs with tree growth in insect-pollinated woody plants is limited, particularly in invasive plants. This study examined patterns of growth and reproductive investment in a North American invasive plant species, Triadica sebifera, I hypothesized that the energy limitations of smaller trees may result in the production of more male reproductive structures that are energetically less costly. Diameter at breast height was a significant predictor of seed and catkin mass and regression can describe these relationships across sites. Seed and catkin mass were positively correlated across sites. The relationship between the seed mass:catkin mass ratio and …

Modeling The Spread Of Sudden Oak Death Across A Heterogeneous Landscape In Redwood National Park Using A Spatially-Explicit Epidemiological Model, Laura A. Morgan

Cal Poly Humboldt theses and projects

The pathogen Phytophthora ramorum, the causal agent of Sudden Oak Death (SOD), is responsible for the deaths of millions of oak (Quercus spp.) and tanoak (Notholithocarpus densiflorus) trees in California and Oregon (USA). A recent infection in Redwood National Park (RNP) in California (USA) provided an opportunity to adapt an existing SOD model to assess the efficacy of current and proposed management strategies. A common method of SOD treatment includes killing both infected and uninfected hosts in the area of infection, as well as the area surrounding the infection to create buffers to account for undetected …