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2019

Ecology and Evolutionary Biology

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Full-Text Articles in Life Sciences

Deep Benthic Coral Habitats Of Glacier Bay National Park And Preserve, Alaska, Elise C. Hartill Aug 2019

Deep Benthic Coral Habitats Of Glacier Bay National Park And Preserve, Alaska, Elise C. Hartill

Electronic Theses and Dissertations

Glacier Bay National Park and Preserve in Southeast Alaska is a system of fjords that presents an ideal natural laboratory to study terrestrial, aquatic and marine patterns of succession due to its unique and recent history of deglaciation. The patterns of deep benthic community assemblages in the fjords of Glacier Bay were investigated by quantitative assessment of underwater photo-quadrats collected using a remotely operated vehicle. The percent cover and diversity of species were lowest near the glaciated heads of the fjords and highest in the Central Channel and at the mouths of the fjords of Glacier Bay, where oceanographic conditions ...


Molecular Phylogeny Of The Pectinoidea (Bivalvia) Indicates Propeamussiidae To Be A Non-Monophyletic Family With One Clade Sister To The Scallops (Pectinidae), G. Dalton Smedley, Jorge A. Audino, Courtney Grula, Anita Porath-Krause, Autum N. Pairett, Alvin Alejandrino, Latayshia Lacey, Felicity Masters, Peter F. Duncan, Ellen E. Strong, Jeanne M. Serb Aug 2019

Molecular Phylogeny Of The Pectinoidea (Bivalvia) Indicates Propeamussiidae To Be A Non-Monophyletic Family With One Clade Sister To The Scallops (Pectinidae), G. Dalton Smedley, Jorge A. Audino, Courtney Grula, Anita Porath-Krause, Autum N. Pairett, Alvin Alejandrino, Latayshia Lacey, Felicity Masters, Peter F. Duncan, Ellen E. Strong, Jeanne M. Serb

Ecology, Evolution and Organismal Biology Publications

Scallops (Pectinidae) are one of the most diverse families of bivalves and have been a model system in evolutionary biology. However, in order to understand phenotypic evolution, the Pectinidae needs to be placed in a deeper phylogenetic framework within the superfamily Pectinoidea. We reconstructed a molecular phylogeny for 60 species from four of the five extant families within the Pectinoidea using a five gene dataset (12S, 16S, 18S, 28S rRNAs and histone H3). Our analyses give consistent support for the non-monophyly of the Propeamussiidae, with a subset of species as the sister group to the Pectinidae, the Propeamussiidae type species ...


Using Tree-Ring Growth And Stable Isotopes To Explore Ponderosa Pine Ecophysiological Responses To Climate Variability And The 2012-2015 California Drought, Rachel M. Keen Aug 2019

Using Tree-Ring Growth And Stable Isotopes To Explore Ponderosa Pine Ecophysiological Responses To Climate Variability And The 2012-2015 California Drought, Rachel M. Keen

All Graduate Theses and Dissertations

Climate warming in recent decades has resulted in more frequent and severe drought events in the western United States. These changes are projected to continue, making it exceedingly important to understand how forests respond to severe drought stress, and how we can manage these forests to reduce mortality during future events. The 2012-2015 California drought is a recent example of a severe, multi-year drought that was coupled with an epidemic-scale outbreak of western pine beetle, killing nearly 90% of ponderosa pines in the central and southern Sierra Nevadas. In the first portion of this study, we compared pairs of surviving ...


Ecosystem Functioning Of Great Salt Lake Wetlands, Maya Cassidy Pendleton Aug 2019

Ecosystem Functioning Of Great Salt Lake Wetlands, Maya Cassidy Pendleton

All Graduate Theses and Dissertations

The Great Salt Lake (GSL) wetlands account for ~75% of all Utah wetlands and provide not only critical habitat for millions of migratory birds, but also provide valuable ecosystem functions and services as well as economic benefits to Utahns. However, these wetlands are facing an aggressive invader, Phragmites australis, that has spreading across the GSL wetlands and replacing native wetland habitats. Wetland managers have spent countless resources and time trying to control the spread of P. australis and restore GSL wetlands. However, we do not fully understand how these wetlands functions and services are being altered with this habitat homogenization ...


Hunting And Mountain Sheep: Do Current Harvest Practices Affect Horn Growth?, Tayler N. Lasharr, Ryan A. Long, James R. Heffelfinger, Vernon C. Bleich, Paul R. Krausman, R. Terry Bowyer, Justin M. Shannon, Robert W. Klaver, Clay E. Brewer, Mike Cox, A. Andrew Holland, Anne Hubbs, Chadwick P. Lehman, Jonathatn D. Muir, Bruce Sterling, Kevin L. Monteith Jul 2019

Hunting And Mountain Sheep: Do Current Harvest Practices Affect Horn Growth?, Tayler N. Lasharr, Ryan A. Long, James R. Heffelfinger, Vernon C. Bleich, Paul R. Krausman, R. Terry Bowyer, Justin M. Shannon, Robert W. Klaver, Clay E. Brewer, Mike Cox, A. Andrew Holland, Anne Hubbs, Chadwick P. Lehman, Jonathatn D. Muir, Bruce Sterling, Kevin L. Monteith

Robert Klaver

The influence of human harvest on evolution of secondary sexual characteristics has implications for sustainable management of wildlife populations. The phenotypic consequences of selectively removing males with large horns or antlers from ungulate populations has been a topic of heightened concern in recent years. Harvest can affect size of horn‐like structures in two ways: 1) shifting age structure toward younger age classes, which can reduce the mean size of horn‐like structures; or 2) selecting against genes that produce large, fast‐growing males. We evaluated effects of age, climatic and forage conditions, and metrics of harvest on horn size ...


Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe Jul 2019

Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe

Michael J Weber

The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 ...


Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe Jul 2019

Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe

Kevin J. Roe

The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 ...


Hunting And Mountain Sheep: Do Current Harvest Practices Affect Horn Growth?, Tayler N. Lasharr, Ryan A. Long, James R. Heffelfinger, Vernon C. Bleich, Paul R. Krausman, R. Terry Bowyer, Justin M. Shannon, Robert W. Klaver, Clay E. Brewer, Mike Cox, A. Andrew Holland, Anne Hubbs, Chadwick P. Lehman, Jonathatn D. Muir, Bruce Sterling, Kevin L. Monteith Jul 2019

Hunting And Mountain Sheep: Do Current Harvest Practices Affect Horn Growth?, Tayler N. Lasharr, Ryan A. Long, James R. Heffelfinger, Vernon C. Bleich, Paul R. Krausman, R. Terry Bowyer, Justin M. Shannon, Robert W. Klaver, Clay E. Brewer, Mike Cox, A. Andrew Holland, Anne Hubbs, Chadwick P. Lehman, Jonathatn D. Muir, Bruce Sterling, Kevin L. Monteith

Natural Resource Ecology and Management Publications

The influence of human harvest on evolution of secondary sexual characteristics has implications for sustainable management of wildlife populations. The phenotypic consequences of selectively removing males with large horns or antlers from ungulate populations has been a topic of heightened concern in recent years. Harvest can affect size of horn‐like structures in two ways: 1) shifting age structure toward younger age classes, which can reduce the mean size of horn‐like structures; or 2) selecting against genes that produce large, fast‐growing males. We evaluated effects of age, climatic and forage conditions, and metrics of harvest on horn size ...


Probability, Populations, Phylogenetics And Hominin Speciation, Niccolo Caldararo Jul 2019

Probability, Populations, Phylogenetics And Hominin Speciation, Niccolo Caldararo

Human Biology Open Access Pre-Prints

A number of recent articles have appeared on the hominin Denisova fossil remains. Many of them focus on attempts to produce DNA sequences from the extracted samples. Often these project mtDNA sequences from the fossil remains of a number of Neandertal fossils and the Denisovans in an attempt to understand the evolution of Mid Pleistocene human ancestors. These papers, introduce a number of problems in the interpretation of speciation in hominins. One concerns the degradation of the ancient DNA and its interpretation as authentic genetic information. Another concerns the idea of “species” versus that of “population” and the use of ...


Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe Jul 2019

Status Of The Topeka Shiner In Iowa, Clay L. Pierce, Nicholas T. Simpson, Alexander P. Bybel, Courtney L. Zambory, Michael J. Weber, Kevin J. Roe

Natural Resource Ecology and Management Publications

The Topeka shiner Notropis topeka is native to Iowa, Kansas, Minnesota, Missouri, Nebraska, and South Dakota and has been federally listed as endangered since 1998. Our goals were to determine the present distribution and qualitative status of Topeka shiners throughout its current range in Iowa and characterize the extent of decline in relation to its historic distribution. We compared the current (2016–2017) distribution to distributions portrayed in three earlier time periods. In 2016–2017 Topeka shiners were found in 12 of 20 HUC10 watersheds where they occurred historically. Their status was classified as stable in 21% of the HUC10 ...


Assessing The Impacts Of Time-To-Detection Distribution Assumptions On Detection Probability Estimation, Adam Martin-Schwarze, Jarad Niemi, Philip Dixon Jul 2019

Assessing The Impacts Of Time-To-Detection Distribution Assumptions On Detection Probability Estimation, Adam Martin-Schwarze, Jarad Niemi, Philip Dixon

Jarad Niemi

Abundance estimates from animal point-count surveys require accurate estimates of detection probabilities. The standard model for estimating detection from removal-sampled point-count surveys assumes that organisms at a survey site are detected at a constant rate; however, this assumption can often lead to biased estimates. We consider a class of N-mixture models that allows for detection heterogeneity over time through a flexibly defined time-to-detection distribution (TTDD) and allows for fixed and random effects for both abundance and detection. Our model is thus a combination of survival time-to-event analysis with unknown-N, unknown-p abundance estimation. We specifically explore two-parameter families of TTDDs, e ...


What Sets Us Apart Could Be Our Salvation, Anne Fawcett, Paul Mcgreevy Jul 2019

What Sets Us Apart Could Be Our Salvation, Anne Fawcett, Paul Mcgreevy

Paul McGreevy, Ph.D.

We agree with Chapman & Huffman that human capacities are often assumed to be unique — or attempts are made to demonstrate uniqueness scientifically — in order to justify the exploitation of animals and ecosystems. To extend the argument that human exceptionalism is against our interests, we recommend adopting the One Welfare framework, according to which animal welfare, environmental sustainability and human wellbeing are inseparably linked. Let us distinguish ourselves from other animals by resisting our short- and mid-term Darwinian inclinations, consuming less, reproducing less, and striving for a much longer-term biological fitness for us all.


A Tentative List Of The Land Snails Of Georgia, U.S.A., Zachary I. Felix, Michael A. Dubuc, Hassan A. Rana Jul 2019

A Tentative List Of The Land Snails Of Georgia, U.S.A., Zachary I. Felix, Michael A. Dubuc, Hassan A. Rana

Georgia Journal of Science

Because of their high ecological and conservation value, and because we know so little about the group, we compiled a systematic if tentative list of land snails from the state of Georgia. After gleaning a list of species from a monograph on the land snails of eastern United States, written by Leslie Hubricht in 1985, we realized that many species whose ecological requirements are found in Georgia had not been documented there. Therefore, we developed a qualitative model to predict the likelihood that these candidate species occur in Georgia and would eventually be documented. We tested the model with collections ...


Automated Bioacoustics: Methods In Ecology And Conservation And Their Potential For Animal Welfare Monitoring, Michael P. Mcloughlin, Rebecca Stewart, Alan G. Mcelligott Jul 2019

Automated Bioacoustics: Methods In Ecology And Conservation And Their Potential For Animal Welfare Monitoring, Michael P. Mcloughlin, Rebecca Stewart, Alan G. Mcelligott

Alan G. McElligott, Ph.D.

Vocalizations carry emotional, physiological and individual information. This suggests that they may serve as potentially useful indicators for inferring animal welfare. At the same time, automated methods for analysing and classifying sound have developed rapidly, particularly in the fields of ecology, conservation and sound scene classification. These methods are already used to automatically classify animal vocalizations, for example, in identifying animal species and estimating numbers of individuals. Despite this potential, they have not yet found widespread application in animal welfare monitoring. In this review, we first discuss current trends in sound analysis for ecology, conservation and sound classification. Following this ...


The Multifaceted Effects Induced By Floods On The Macroinvertebrate Communities Inhabiting A Sinking Cave Stream, Octavian Pacioglu, Nicoleta Ianovici, Mărioara N. Filimon, Adrian Sinitean, Gabriel Iacob, Henrietta Barabas, Alexandru Pahomi, Andrei Acs, Hanelore Muntean, Lucian Pârvulescu Jul 2019

The Multifaceted Effects Induced By Floods On The Macroinvertebrate Communities Inhabiting A Sinking Cave Stream, Octavian Pacioglu, Nicoleta Ianovici, Mărioara N. Filimon, Adrian Sinitean, Gabriel Iacob, Henrietta Barabas, Alexandru Pahomi, Andrei Acs, Hanelore Muntean, Lucian Pârvulescu

International Journal of Speleology

First-order sinking cave streams experience considerable hydrological variability, including spates and periods of base-flow during dry seasons. Early-summer flooding on a first-order stream sinking in Ciur-Ponor Cave (Romania) represented a suitable opportunity to test the response of the macroinvertebrate community and of basal food resources quantity and diversity to such a disturbance event. The invertebrate community and basal resources (i.e., woody debris, leaves, fine particulate organic matter and epilithon) were collected from three sampling sites, before and after the flood. The sampling strategy followed an up-downstream gradient of both species diversity and quantity of allochtonous organic matter decrease as ...


Species-Area Model Predicting Diversity Loss In An Artificially Flooded Cave In Brazil, Rodrigo L. Ferreira, Thais G. Pellegrini Jul 2019

Species-Area Model Predicting Diversity Loss In An Artificially Flooded Cave In Brazil, Rodrigo L. Ferreira, Thais G. Pellegrini

International Journal of Speleology

Subterranean environments are poorly known regarding many ecological aspects, such as community structure and its response to different disturbances. To estimate the effects of ground area lost in a limestone cave community in Southeastern Brazil, the invertebrate fauna was sampled before 76% of the cave floor was submerged by the filling of a hydroeletric power plant reservoir. Then, a 2-year monitoring was conducted. A species-area curve based on empiric data was constructed and the z-value of the species-area equation was calculated, what allowed estimating the expected cave richness after flooding comparing with data obtained during the monitoring. The results support ...


Factors Affecting Nest Success Of Colonial Nesting Waterbirds In Southwest Louisiana, Karis A. Ritenour Jul 2019

Factors Affecting Nest Success Of Colonial Nesting Waterbirds In Southwest Louisiana, Karis A. Ritenour

LSU Master's Theses

As the coastline of Louisiana shifts with global climate change, subsidence, and accelerated sea level rise, important breeding islands for colonial nesting waterbirds are disappearing. In many recent studies flooding has been a leading cause of nest failure for a variety of species, especially those that nest on the ground. I examined the nest success of four species of colonial nesting waterbirds with various nesting strategies on Rabbit Island in southwestern Louisiana during 2017 and2018 by determining nest and fledging success. I monitored 855 nests, including 457 Brown Pelicans nests with an estimated hatch probability of 70%, 270 Forster’s ...


Beyond The Black Box: Promoting Mathematical Collaborations For Elucidating Interactions In Soil Ecology, Alison E. Bennett, Lori Biederman, Matthew Warren, Et Al. Jul 2019

Beyond The Black Box: Promoting Mathematical Collaborations For Elucidating Interactions In Soil Ecology, Alison E. Bennett, Lori Biederman, Matthew Warren, Et Al.

Ecology, Evolution and Organismal Biology Publications

Understanding soil systems is critical because they form the structural and nutritional foundation for plants and thus every terrestrial habitat and agricultural system. In this paper, we encourage increased use of mathematical models to drive forward understanding of interactions in soil ecological systems. We discuss several distinctive features of soil ecosystems and empirical studies of them. We explore some perceptions that have previously deterred more extensive use of models in soil ecology and some advances that have already been made using models to elucidate soil ecological interactions. We provide examples where mathematical models have been used to test the plausibility ...


Short Term Shifts In Soil Nematode Food Feb Structure And Nutrient Cycling Following Sustainable Soil Management In A California Vineyard, Holly M. Deniston-Sheets Jul 2019

Short Term Shifts In Soil Nematode Food Feb Structure And Nutrient Cycling Following Sustainable Soil Management In A California Vineyard, Holly M. Deniston-Sheets

Master's Theses and Project Reports

Evaluating soil health using bioindicator organisms has been suggested as a method of analyzing the long-term sustainability of agricultural management practices. The main objective of this study was to determine the effects of vineyard management strategies on soil food web structure and function, using nematodes as bioindicators by calculating established nematode ecological indices. Three field trials were conducted in a commercial Pinot Noir vineyard in San Luis Obispo, California; the effects of (i) fertilizer type (organic and inorganic), (ii) weed management (herbicide and tillage), and (iii) cover crops (high or low water requirements) on nematode community structure, soil nutrient content ...


Arts Of Living On A Damaged Planet: Ghosts And Monsters Of The Anthropocene By Anna Lowenhaupt Tsing, Heather Anne Swanson, Elaine Gan, And Nils Bubandt, Randy Lee Cutler Jun 2019

Arts Of Living On A Damaged Planet: Ghosts And Monsters Of The Anthropocene By Anna Lowenhaupt Tsing, Heather Anne Swanson, Elaine Gan, And Nils Bubandt, Randy Lee Cutler

The Goose

Review of Anna Lowenhaupt Tsing, Heather Anne Swanson, Elaine Gan, and Nils Bubandt's Arts of Living on a Damaged Planet: Ghosts and Monsters of the Anthropocene.


Eocene Terrestrial Mammals From Central Georgia, Parker D. Rhinehart, Alfred J. Mead, Dennis Parmley Jun 2019

Eocene Terrestrial Mammals From Central Georgia, Parker D. Rhinehart, Alfred J. Mead, Dennis Parmley

Georgia Journal of Science

Descriptions of fossils of Eocene terrestrial mammals from the southeastern United States are rare, and particularly so in the Eocene sediments of Georgia. Here we describe a small collection of fossilized teeth and tooth fragments representing four mammalian taxa. The fossils were recovered by surface collecting overburden sediments and screen washing in situ Clinchfield Formation sediments exposed in an inactive kaolin mine, Hardie Mine, in Wilkinson County, Georgia. The Clinchfield Formation has been described as a Late Eocene coastal unit with abundant gastropods, bivalves, sharks, and rays. This is the first detailed description of terrestrial mammals from this unit. Although ...


Sex-Specific Personalities In The Purple Marsh Crab, Jillian Sterman, Jessica Barton, Panagiota Delmedico, Samantha Sweeney Jun 2019

Sex-Specific Personalities In The Purple Marsh Crab, Jillian Sterman, Jessica Barton, Panagiota Delmedico, Samantha Sweeney

DePaul Discoveries

Animals are considered to possess personalities when individuals differ in behavior, and these differences are consistent between situations. Several studies have identified personalities in diverse groups but less is known about personality variation between the sexes. In this study, we examined variation in two key personality traits (boldness, activity) in female and male purple marsh crabs (Sesarma reticulatum) using a semi-field approach. Specifically, we measured boldness and activity on two consecutive days using the same behavioral assays during each time point. Consistency (personality) was determined using Kendall’s coefficient of concordance based on Spearman correlation coefficients for each behavior. The ...


Effects Of Reduced Ph On Health Biomarkers Of The Seagrass Cymodocea Nodosa, Regan A. Mcenaney Jun 2019

Effects Of Reduced Ph On Health Biomarkers Of The Seagrass Cymodocea Nodosa, Regan A. Mcenaney

DePaul Discoveries

Ocean acidification is a growing problem that may affect many marine organisms in the future. Within 100 years the pH of the ocean is predicted to decrease to 7.8, from the current ocean pH of around 8.1. Using phenolic acid levels as a stress indicator as well as respiration and chlorophyll content as a measure of health, the effect of lowering pH was tested on the seagrass, Cymodocea nodosa, in a controlled environment. Plant samples, water, and soil were taken from the Bay of Cádiz, Spain, and placed in aquaria in a temperature-controlled room. One control group was ...


Relating Spatial Patterns Of Stream Metabolism To Distributions Of Juveniles Salmonids At The River Network Scale, Matthew J. Kaylor, Seth M. White, W. Carl Saunders, Dana R. Warren Jun 2019

Relating Spatial Patterns Of Stream Metabolism To Distributions Of Juveniles Salmonids At The River Network Scale, Matthew J. Kaylor, Seth M. White, W. Carl Saunders, Dana R. Warren

Watershed Sciences Faculty Publications

Understanding the factors that drive spatial patterns in stream ecosystem processes and the distribution of aquatic biota is important to effective management of these systems and the conservation of biota at the network scale. In this study, we conducted field surveys throughout an extensive river network in NE Oregon that supports diminishing populations of wild salmonids. We collected data on physical habitat, nutrient concentrations, biofilm standing stocks, stream metabolism (gross primary production [GPP] and ecosystem respiration [ER]), and ESA‐listed juvenile salmonid density from approximately 50 sites across two sub‐basins. Our goals were to (1) to evaluate network patterns ...


When An Invasive Plant Fails To Invade, Stephen L. Young Jun 2019

When An Invasive Plant Fails To Invade, Stephen L. Young

Stephen L. Young

In 2012, much of the US Midwest was gripped in one of the most severe droughts on record. While conducting experimental fieldwork at a site in Nebraska during June of that year, I noticed a single musk thistle (Carduus nutans; Figure 1) that appeared to be in the bolt or early flowering stage, which is typical for the species at that time. Here, however, two things were unusual: this plant was less than 1 meter tall (with adequate moisture and light, musk thistle typically grows to heights of 1–2.5 meters before flowering), and was only 3 months old ...


The Paper Trail: An Arid Connection & A Book Of A Thousand Plants, Stephen L. Young, Peter Alpert Jun 2019

The Paper Trail: An Arid Connection & A Book Of A Thousand Plants, Stephen L. Young, Peter Alpert

Stephen L. Young

Following my Ph.D., I moved on to Nebraska, where as a beginning faculty member I was able to start a research program in ecology and continue to study what intrigued me most: plant competition and stress. It was during this time that I came across the paper by Peter Alpert (see his article below) and his colleagues on “Invasiveness, invasibility, and the role of environmental stress in preventing the spread of non-native plants” (Perspectives in Plant Ecology, Evolution and Systematics 3:52–66). It was an “aha” moment in reading about biological invasion research and the current consensus at ...


Root Growth Of Two Perennial Grass Types And Musk Thistle (Carduus Nutans) In Temperate Grasslands Of North America, Chengchou Han, Stephen L. Young Jun 2019

Root Growth Of Two Perennial Grass Types And Musk Thistle (Carduus Nutans) In Temperate Grasslands Of North America, Chengchou Han, Stephen L. Young

Stephen L. Young

Root architecture of prairie grasslands, which depends on plant phenology and edaphic conditions, strongly influences susceptibility to invasion by nonindigenous plant species. Field studies were conducted to compare in situ root growth patterns of warm-season (WS) and cool-season (CS) perennial grasses and musk thistle during a 2-yr period that included a drought in the second year. In 2 yr, CS grasses had the highest amount of roots (1,296 m roots m–2 [395 ft roots ft–2]) across shallow (0 to 28 cm [0 to 11 in.]), medium (28 to 56 cm), and deep (56 to 98 cm) depths ...


Invasion During Extreme Weather: Success And Failure In A Temperate Perennial Grassland, James C. Han, Stephen L. Young Jun 2019

Invasion During Extreme Weather: Success And Failure In A Temperate Perennial Grassland, James C. Han, Stephen L. Young

Stephen L. Young

Invasive and native plant species compete for resources in similar pools, with disturbances often favoring the invader. Yet, increased climate variability may be shifting the competitive edge back toward the natives. We conducted field studies in perennial grasslands to determine the effects of clipping and drought on resource availability (light and moisture) and subsequent establishment of Carduus nutans. We measured light penetration and soil moisture content in C. nutans monoculture, clipped and non clipped grassland with C. nutans, and bare ground control plots. We also tracked phenology of the invader and grasses. Our studies revealed that light was a limiting ...


Climate Dynamics, Invader Fitness, And Ecosystem Resistance In An Invasion-Factor Framework, Stephen L. Young, David R. Clements, Antonio Ditommaso Jun 2019

Climate Dynamics, Invader Fitness, And Ecosystem Resistance In An Invasion-Factor Framework, Stephen L. Young, David R. Clements, Antonio Ditommaso

Stephen L. Young

As researchers and land managers increasingly seek to understand plant invasions and the external (climate) and internal (plant genetics) conditions that govern the process, new insight is helping to answer the elusive question of what makes some invasions successful and others not. Plant invasion success or failure is based on a combination of evolutionary and ecological processes. Abiotic (e.g., climate) and biotic (e.g., plant competition) conditions in the environment and plant genetics (e.g., fitness) combine in either decreasing or increasing invasion, yet it has proven challenging to know exactly which of these conditions leads to success for ...


Cattle Grazing Effects On Phragmites Australis In Nebraska, Jerry D. Volesky, Stephen L. Young, Karla H. Jenkins Pas Jun 2019

Cattle Grazing Effects On Phragmites Australis In Nebraska, Jerry D. Volesky, Stephen L. Young, Karla H. Jenkins Pas

Stephen L. Young

Phragmites australis (common reed) is one of the most widely distributed flowering plants in North America. The introduced lineage occurs in wetland and riparian areas covering a range of climatic types. In Nebraska, an abundance of livestock could help to reduce P. australis with proper timing and grazing intensities. In 2011, a 3-yr study was initiated to evaluate targeted cattle grazing and herbicide effects and the nutritive value of this species. Treatments included a single application of imazapyr (Habitatt, BASF Corporation, Research Triangle Park, NC) herbicide applied in the first year, grazing, and a control. Grazing was applied for up ...