2016

Varun Acharya

v-acharyaVarun and Lili’s 2016 REU project was, “Impacts of shrub encroachment on small mammal populations and plant diversity in the Northern Chihuahuan Desert ecosystem.”

Shrub encroachment is a continuing habitat change in the Northern Chihuahuan desert, broughtabout by both grazing and climatic changes. The increased abundance of Creosote shrubs (Larrea tridentata) has been known to decrease species diversity and impact water and nutrient cycles. The occurrence of shrub encroachment in New Mexico has been extensively studied, but little is known about the transitional effects on small mammal populations. Small mammal trapping occurred at four study sites during the summer of 2016. Each site included three plots: a grassland, shrubland, and ecotone habitat. Plant cover was recorded along the same trapping transects. As shrubs overtake grasslands, there is more bare soil available to burrowing rodents and there is a significant positive correlation between bare soil cover and total rodent abundance. There is no significant difference in rodent diversity or richness between the three habitats despite the difference in plant community structure. The impacts of shrub encroachment on small mammal populations relates to the broader concern of desert sensitivity to climate change and poor land management. Our study aims to identify these impacts, and better understand the relationship between desert rodents and plant community structure.

Sarah Fischer

s-fischerSarah and Henry’s 2016 REU project was, “Gray Vireo (Vireo vicinior) nest success and territory characteristics in Los Pinos Mountains.”

Gray Vireos (Vireo vicinior) are short-distance migrants that occur throughout northwestern Mexico and arid regions of the southwestern United States. This species is not well studied throughout its range, and is currently listed as threatened in the state of New Mexico (NM). We will monitor Gray Vireos on three study sites within the Sevilleta National Wildlife Refuge, NM — Pinyon Canyon, Bootleg Canyon and Sepultura Flats — to gain a better understanding of Gray Vireo breeding ecology and to augment the limited information available regarding this species. Our objectives are to 1) locate and monitor nests to determine overall nest success, 2) estimate rate and impact of nest parasitism by Brown-headed Cowbirds (Molothrus ater), 3) estimate territory sizes for each breeding pair, and 4) record and quantify vegetation structure and diversity around nesting sites and within territory ranges to determine overall habitat preferences. We expect to record the largest number of breeding pairs in areas dominated by one-seed juniper (Juniperus monosperma), the preferred nesting tree of Gray Vireos in the central portion of the state. We hypothesize a positive relationship between the number of breeding pairs and density of one-seed juniper as well as other habitat variables known to reflect habitat quality. Additionally, we expect to record higher rates of brood parasitism in areas adjacent to cattle grazing. Our results may be useful in refining current management practices throughout the Gray Vireo’s range.

Ashley Frost

a-frostAshley’s 2016 REU Project was, “Fungal endophyte influence on competition between grass species in the southwest.”

Bouteloua gracilis and Bouteloua eriopoda are species of grasses that compete in the Southwestern United States. It is unclear why these competing grasses coexist in some areas. One hypothesis is that pathogenic, species-specific, fungal endophytes may facilitate coexistence between the grass species. The pathogenic endophytes may limit the growth and reproductive success of their host, and, prevent the stronger grass competitor from out-competing the weaker grass. A competition experiment between blue and black grama was conducted at the Sevilleta National Wildlife Refuge. One goal for this experiment was to understand how these grasses compete; to fully study the competitive interaction the grasses were grown in either intraspecific or interspecific competition pot compositions. The outcome of the competitive interaction was quantified by observing the rate of seedling death. An ongoing component of this experiment will be to understand how fungal endophytes affect the competition between these grasses. I will inoculate these grass species with five different fungi: Bipolaris spicifera, Monosporascus cannonballus, Paraconiothyrium brasiliense, Tiarosporella rosarum, and Chaetomium globosum, which are naturally found in the tissue of the grasses.  These single fungus inoculation treatments will be compared to grasses grown in soil taken from the Deep Well Site, a site on the Sevilleta National reserve where Blue and Black grama coexist.

Joaquin Garcia

j-garciaJoaquin and Angela’s 2016 REU project was, “Gunnison’s Prairie Dog response to prescribed burn and vegetation height reduction during the initial reintroduction period.”

In the ecology of plains habitats, prairie dogs are a keystone species and ecosystem engineer. Prairie dogs and their burrows provide shelter for many different species of organisms, increase water permeability, add organic matter to the soil, and serve as an important prey species. Historically, the Gunnison’s prairie dog (Cynomys gunnisoni) was present on the land that is now the Sevilleta National Wildlife Refuge (SNWR). However, ranchers extirpated prairie dogs from the area in the 1960’s. Reintroduction of the Gunnison’s prairie dog began in 2010 and has now grown to encompass four separate 9 hectare plots, with over 3,000 individuals having been released since 2010. Prescribed fire has been shown to help with the expansion of black tailed prairie dog communities, and previous studies at the SNWR showed that prescribed burn increased settling and survival rates of reintroduced prairie dogs. Prairie dogs are a highly social species that use communication and alarm calls to warn others of predators, and the reduced vegetation height of burned areas is presumed to aid in predator detection. This experiment tests reintroduced Gunnison’s prairie dogs’ response to prescribed burns and reduced vegetation height. We used trapping and  behavioral observations to collect data on density of treatment versus control plots and movement of individual prairie dogs. We hypothesize that the burned plots will contain a higher density of individuals when compared to the unburned controls, and higher rates of movement towards treatment plots.

Angela Ingrassia

a-ingrassiaAngela and Joaquin’s 2016 REU project was, “Gunnison’s Prairie Dog response to prescribed burn and vegetation height reduction during the initial reintroduction period.”

In the ecology of plains habitats, prairie dogs are a keystone species and ecosystem engineer. Prairie dogs and their burrows provide shelter for many different species of organisms, increase water permeability, add organic matter to the soil, and serve as an important prey species. Historically, the Gunnison’s prairie dog (Cynomys gunnisoni) was present on the land that is now the Sevilleta National Wildlife Refuge (SNWR). However, ranchers extirpated prairie dogs from the area in the 1960’s. Reintroduction of the Gunnison’s prairie dog began in 2010 and has now grown to encompass four separate 9 hectare plots, with over 3,000 individuals having been released since 2010. Prescribed fire has been shown to help with the expansion of black tailed prairie dog communities, and previous studies at the SNWR showed that prescribed burn increased settling and survival rates of reintroduced prairie dogs. Prairie dogs are a highly social species that use communication and alarm calls to warn others of predators, and the reduced vegetation height of burned areas is presumed to aid in predator detection. This experiment tests reintroduced Gunnison’s prairie dogs’ response to prescribed burns and reduced vegetation height. We used trapping and  behavioral observations to collect data on density of treatment versus control plots and movement of individual prairie dogs. We hypothesize that the burned plots will contain a higher density of individuals when compared to the unburned controls, and higher rates of movement towards treatment plots.

Olivia Judson

o-judsonOlivia’s 2016 REU project was, “Exploring similarities between fungal communities found in grass and in feces.”

There is evidence to show that endophytes are capable of living as coprophiles and vice versa. To provide more evidence for this dual lifestyle hypothesis, fungal DNA sequences from feces and the taxa associated with those sequences were obtained and compared to those obtained sequences and associated fungal taxa from grass. However, this did not occur due to a lack of adequate time to complete the project. It was discovered that plant samples were mostly blue grama, with some Poa spp. and one sedgegrass. In fecal samples there was found to be DNA from a protist genus Hexamastix spp. as well as two flowering desert plants. In the future, the data obtained from this project can be analyzed fully and potentially provide evidence for the dual lifestyle hypothesis.

Lilian Kaeding

l-kaedingLili and Varun’s 2016 REU project was, “Impacts of shrub encroachment on small mammal populations and plant diversity in the Northern Chihuahuan Desert ecosystem.”

Shrub encroachment is a continuing habitat change in the Northern Chihuahuan desert, broughtabout by both grazing and climatic changes. The increased abundance of Creosote shrubs (Larrea tridentata) has been known to decrease species diversity and impact water and nutrient cycles. The occurrence of shrub encroachment in New Mexico has been extensively studied, but little is known about the transitional effects on small mammal populations. Small mammal trapping occurred at four study sites during the summer of 2016. Each site included three plots: a grassland, shrubland, and ecotone habitat. Plant cover was recorded along the same trapping transects. As shrubs overtake grasslands, there is more bare soil available to burrowing rodents and there is a significant positive correlation between bare soil cover and total rodent abundance. There is no significant difference in rodent diversity or richness between the three habitats despite the difference in plant community structure. The impacts of shrub encroachment on small mammal populations relates to the broader concern of desert sensitivity to climate change and poor land management. Our study aims to identify these impacts, and better understand the relationship between desert rodents and plant community structure.

Julie LeVonne

j-levonneJulie’s 2016 REU project was, “Plant-Species interactions in Sphaeralcea polychroma and S.incana.”

Sphaeralcea polychroma is a relatively understudied species.  This study aimed to explore the relationship between S. polychroma’s continuous floral color variation and fitness. This study also explores three facets of interactions that S. Polychroma has with its environment: herbivory, fungal, and insect.  Additionally, S. polychroma is compared to a closely related species, S. incana in terms of growth rate, herbivory, and presence of fungus.  While no significant difference was found between the two species in regards to average growth rate per week for the first five weeks when plants were watered once per day, this study found a significant difference in growth rates between S. incana and S. polychroma when plants were watered twice per day.

Andrea Lopez

a-lopezAndrea’s 2016 REU project was, “Method application of the Tea Bag Index in predicting the impact of irregular monsoon seasons on Chihuahuan Desert grasslands.”

Regions of the Chihuahuan desert grasslands dominated by Bouteloua gracilis (Blue grama) and Bouteloua eriopoda (Black Grama) are disappearing due to increasing drought conditions, shrub encroachment, and irregular fire events. In Southern New Mexico, climate change predictions suggest that strong variations in the monsoon season. Irregular precipitation may have an effect on the decomposition rates of plant litter in semi-arid grasslands. The black grama and blue grama dominated EDGE research sites located at the Sevilleta LTER station gather plant composition data on the impact of event size reduction (ESR) and shifted monsoon events. Utilizing the Tea Bag Index method (TBI), this research project attempts to test the hypothesis that variations in the monsoon season will have a negative impact in the decomposition rates of black grama and blue grama grasslands. A decomposition rate will be calculated from difference in mass through time with the formula utilized by Keuskamp et al. 2013, W(t)= ae-kt+(1-a). Placement of tea bags consisted of 300 buried at an 8 cm depth and 120 surface tea bags placed on top of grass clumps per site. Tea bag collection will take place on day 30 for preliminary decomposition analysis between site and treatments. It is predicted that drought treatment will have a lower decomposition rate than a shifted monsoon event, and that blue grama decomposition rate will be lower than black grama.  Data collected will contribute to grassland soil maps and global climate change databases.

Sebastian Martinez

s-martinezSebastian’s 2016 REU project was, “Lizard community responses to grassland disturbances in prairie dog towns.”

The purpose of this project was to improve our understanding on the effects of burning and mowing grasses in prairie dog towns on lizard abundance and diversity. This study adds to the knowledge of the effects of prairie dog habitat management on the sympatric lizard community. Previous studies documented that lizard abundance is greater in prairie dog towns, but did not address the temporal effects or the role of management disturbances in this system. This project adds to work previously studied at Sevilleta National Wildlife Refuge (SNWR) after the managed burns and mowing within the prairie dog towns. This comparison of pre- and post- habitat enhancement via simulated disturbances potentially provides managers with insights into the cascading effects of management actions to co-existing, non-target species. Building on previous projects, the study’s results suggested that lizard abundance was higher in plots with prairie dogs. The results also suggested that the little striped whiptail only occurred in trail plots away from Los Pinos Mountains. However, no trends were seen on the managed plots.

Emir Padron

Speed Star 1.1441397  00Emir’s 2016 REU project was, “Odonata Survey of the La Joya Wildlife Area.”

La Joya Wildlife Area is located about 20 miles north of Socorro, within the state of New Mexico; the climate of the region ranges from semiarid to arid. It is also, characterized by a weather of abundant sunshine, low precipitations, low humidity and high diurnal temperatures. As a result of those conditions water can be a limited resource around the landscape. Surprisingly and in spite of the preponderant conditions of the region La Joya has a significant amount of body of waters. And this wetlands, ponds, agriculture canals, and drains become an oasis and the home of a vast number animals. The Odonata are an essential part of a varied community of insects that lives within the area. These insects depend on the bodies of water to be able to complete their life cycles. In this survey we are aiming to determinate their distribution and richness in the area. To survey and compare the diversity of this insects we have chosen different types of habitats with different sizes on their bodies of water.

Henry Stevens

h-stevensHenry and Sarah’s 2016 REU project was, “Gray Vireo (Vireo vicinior) nest success and territory characteristics in Los Pinos Mountains.”

Gray Vireos (Vireo vicinior) are short-distance migrants that occur throughout northwestern Mexico and arid regions of the southwestern United States. This species is not well studied throughout its range, and is currently listed as threatened in the state of New Mexico (NM). We will monitor Gray Vireos on three study sites within the Sevilleta National Wildlife Refuge, NM — Pinyon Canyon, Bootleg Canyon and Sepultura Flats — to gain a better understanding of Gray Vireo breeding ecology and to augment the limited information available regarding this species. Our objectives are to 1) locate and monitor nests to determine overall nest success, 2) estimate rate and impact of nest parasitism by Brown-headed Cowbirds (Molothrus ater), 3) estimate territory sizes for each breeding pair, and 4) record and quantify vegetation structure and diversity around nesting sites and within territory ranges to determine overall habitat preferences. We expect to record the largest number of breeding pairs in areas dominated by one-seed juniper (Juniperus monosperma), the preferred nesting tree of Gray Vireos in the central portion of the state. We hypothesize a positive relationship between the number of breeding pairs and density of one-seed juniper as well as other habitat variables known to reflect habitat quality. Additionally, we expect to record higher rates of brood parasitism in areas adjacent to cattle grazing. Our results may be useful in refining current management practices throughout the Gray Vireo’s range.

Dennis Suazo

d-suazoDennis’ 2016 REU project was, “Amphibian survey of the Bernardo Waterfowl Management Area and the Sevilleta National Wildlife Refuge.”

The Sevilleta National Wildlife Refuge is home to a variety of species that are adapted to the many types of environments found there. Characterization of the species found on the refuge is important for conservation and for furthering our understanding of arid/semiarid ecosystems. No recent effort has been made to characterize the species of frogs and toads in the Sevilleta NWR. Identification of different amphibian species is being mediated through analysis of vocalization recordings and from photographs of the organisms. We had hoped to find evidence of species of concern such as the Northern Leopard frog Rana pipiens pipiens and the Boreal chorus frog Pseudacris t. maculata, but we expect that the encroachment of the invasive American Bullfrog Lithobates catesbeianus is having detrimental effects on species richness in the riparian area of the Sevilleta NWR. Audio recorded in the Bernardo Waterfowl Management Area suggest that there are more American Bullfrogs calling than other frogs and toads in the area, perhaps indicating that they are dominating the resource of calling time and calling space.

Bradly Thornton

b-thorntonBrad’s 2016 REU project was, “Effect of cyanobacteria-dominated biological soil crusts on localized hydrologic cycles and nutrient cycling.”

Biological soil crusts (biocrusts) exist as the dominant living cover in arid ecosystems between patches of vascular plants. Contributing to significant ground cover in these ecosystems, biocrusts possess features that can alter local hydrologic cycles and nutrient cycling. The role of cyanobacteria-dominated biocrusts in these processes has been studied before; however, few studies have experimentally manipulated biocrusts at the whole-community scale within different ecosystems. Further, few studies have sought to characterize these localized hydrological and nutrient cycling processes using chlorophyll a as an indicator for biocrust activity. In this study, I investigated soil hydrological properties including infiltration rate, depth of water infiltration, runoff capacity, aggregate stability, and water content in intact and disturbed patches of biocrusts in two ecosystem types (grassland and shrubland). I examined localized nutrient cycling through a C:N analysis of leaf and root clips collected from black grama (Bouteloua eriopoda) plants. Comparing these processes with the level of chlorophyll a, this study found soil surface stability was negatively affected by biocrust disturbance and infiltration depth increased with biocrust disturbance. However, other soil-hydrologic responses were not impacted by the disturbance, indicating that local soil-hydrologic and nutrient cycling may be affected more by ecosystem-specific variation in plant community structure and/or soil edaphic characteristics than by cyanobacteria-dominated biocrusts. This study provides evidence for utilizing chlorophyll a as an indicator for the activity of cyanobacteria-dominated soil crusts and the importance for future biocrust research to consider the effects of ecosystem characteristics.

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