Browsing by Subject "Big Bend National Park"
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Item Bone histology of the sauropod dinosaur Alamosaurus sanjuanensis from the Javelina Formation, Big Bend National Park, Texas(2005-05) Woodward, Holly N.; Lehman, Thomas; Barrick, James E.; Chatterjee, SankarBone samples of the sauropod dinosaur Alamosaurus sanjuanensis were collected from the Upper Cretaceous Javelina Formation in Big Bend National Park, Texas, for use in a histological analysis. Alamosaurus is a member of the Titanosauridae, the most derived sauropod group. This is the first extensive histological study performed on a member of the Titanosauridae, although previous studies indicated that the vertebral structure in this group is unlike that of any other sauropod family. Parts of twelve ribs; two tibiae; three humeri; one scapula; two fibulae; three femora; one pubis; one ulna; one metacarpal II(?); one metatarsal II(?); two dorsal vertebrae; and two distal caudal vertebrae were examined. The specimens were sectioned and imaged digitally using a flatbed scanner as well as prepared for thin section analysis. The ribs and vertebrae are highly cavernous. The vertebrae possess "camellate" cavities unique to titanosaurids. The ribs are also highly cavernous throughout their length, a feature previously unreported in other sauropods. Several distal rib specimens possess calcified cartilage, suggesting a connection to cartilagenous sternal ribs. The pubis and scapula were the first skeletal elements to be completely remodeled by, 50 percent adult length. Primary tissue, where present, is typically of the woven to fibro-lamellar type. Lamellar-zonal tissue with annuli was only found in the peripheral cortex of a tibia 74 percent adult length, a humerus 78 percent adult length, and in several rib fragments. Several appendicular elements exhibit growth rings, or "cycles". By estimating body mass from the percent adult length at each cycle, and applying the von Bertalanffy growth rate equation, a growth curve is produced. Using a humerus sample possessing the best preserved cycles, Alamosaurus is estimated to have attained adult mass in 60 years. This method is also used to provide age estimates for previous sauropod growth rate studies.Item Bone histology of the sauropod dinosaur Alamosaurus sanjuanensis from the Javelina Formation, Big Bend National Park, Texas(Texas Tech University, 2005-05) Woodward, Holly Noelle; Lehman, Thomas; Barrick, James E.; Chatterjee, SankarBone samples of the sauropod dinosaur Alamosaurus sanjuanensis were collected from the Upper Cretaceous Javelina Formation in Big Bend National Park, Texas, for use in a histological analysis. Alamosaurus is a member of the Titanosauridae, the most derived sauropod group. This is the first extensive histological study performed on a member of the Titanosauridae, although previous studies indicated that the vertebral structure in this group is unlike that of any other sauropod family. Parts of twelve ribs; two tibiae; three humeri; one scapula; two fibulae; three femora; one pubis; one ulna; one metacarpal II(?); one metatarsal II(?); two dorsal vertebrae; and two distal caudal vertebrae were examined. The specimens were sectioned and imaged digitally using a flatbed scanner as well as prepared for thin section analysis. The ribs and vertebrae are highly cavernous. The vertebrae possess “camellate” cavities unique to titanosaurids. The ribs are also highly cavernous throughout their length, a feature previously unreported in other sauropods. Several distal rib specimens possess calcified cartilage, suggesting a connection to cartilagenous sternal ribs. The pubis and scapula were the first skeletal elements to be completely remodeled by, 50 percent adult length. Primary tissue, where present, is typically of the woven to fibro-lamellar type. Lamellar-zonal tissue with annuli was only found in the peripheral cortex of a tibia 74 percent adult length, a humerus 78 percent adult length, and in several rib fragments. Several appendicular elements exhibit growth rings, or “cycles”. By estimating body mass from the percent adult length at each cycle, and applying the von Bertalanffy growth rate equation, a growth curve is produced. Using a humerus sample possessing the best preserved cycles, Alamosaurus is estimated to have attained adult mass in 60 years. This method is also used to provide age estimates for previous sauropod growth rate studies.Item Common trail insects of Big Bend National Park(Texas Tech University, 2002-05) So, Tanya M.Big Bend National Park, the United States' twenty-seventh national park, was established by Congress on June 12, 1944, setting aside 708,221 acres of desert and mountain terrain to protect for future generations (Jameson 1996). Selected for its dramatic scenery, geologic features, and unique plant and animal communities, it also provides the best example of Chihuahuan Desert ecology in the United States (Maxwell 1968, Wauer 1973). Although the Chihuahuan Desert is the largest of the three creosotebush dominated deserts in North America, it is also the least understood (Brown 1994). Entomologists estimate over 5,000 species of insects occur within Big Bend National Park. Yet only about 4,000 have been identified, and only a handful of the many orders have been studied with any thoroughness (Van Pelt 1995, Wauer 1973). The first large, general study of insects in Big Bend National Park was made by R. H. Baker in 1937 as a background study for the proposed national park. Subsequent studies have been confined mostly to specific orders, families, or genera with the exception of Van Pelt's 1995 armotated inventory of insects in the park (Van Pelt 1995). However, this work is based on secondary sources and has no insect descriptions or photographs. In fact, with the exception of Roland Wauer's recent Butterflies of West Texas Parks and Preserves, there have been no field guides on the insects of Big Bend Nafional Park (Wauer 2002). The purpose of the present study is to provide an easy-to-use field guide for the layperson as an aid in identifying commonly encountered insects in the park. It focuses on some of the higher-profile, "charismatic," or easily noficed insects that a casual visitor stopping at highly frequented areas within the park is likely to see. In addition to aiding in insect identification, this guide is intended to be educational in providing information on insect distribution, habitat, and behavior. In helping people become more familiar with the world of desert invertebrates, 1 hope that this guide will foster a broader ecological understanding of desert environments and ultimately encourage conservation of our natural resources.Item Culturability and dynamics of bacterial communities along the Pine Canyon Watershed of Big Bend National Park, TX(2007-12) Clark, Jeb; Zak, John; Francisco, Michael J. D. S.; Jeter, Randall M.Soil bacterial communities are known to play a significant role in ecosystems as they are responsible for, among other things, nutrient cycling, and plant and rhizosphere interactions. Those bacterial communities which persist in arid environments have gained special attention over the past several years as life in these environments is often believed to be limited due to a lack of available water. Since soil bacteria play such a significant role in the environment, understanding how seasonal changes in soil moisture and temperature affect bacterial community structure and function is critical for understanding how soil bacteria contribute to the functioning of arid ecosystems. However, the study of soil bacterial communities has been limited due to difficulties experienced in culturing organisms from the environment. Furthermore, PCR-based, culture-independent techniques have become increasingly popular amongst researchers, but these techniques which impose a bias limiting observations to only the most DNA-dominant bacterial species, species which are not believed to play a large functional role in the ecosystem. Hence, a large and possibly important proportion of the bacterial population could be commonly overlooked. A year-long, two-part research project on the environmental effects on soil bacterial communities in three sites along the Pine Canyon Watershed of Big Bend National Park began in August 2005. The first part examined the DNA-dominant bacterial community structure using PCR and Denaturing Gradient Gel Electrophoresis along with Fatty Acid Methyl Ester analysis. These techniques revealed a stable DNA-dominant bacterial community structure throughout the summer and winter seasons, and no significant changes in bacterial structure were recorded during a large precipitation event during August 2006. The second study utilized a culture-based approach to examine the functional bacterial communities along the three sites. The culture-based approach revealed that two different assemblages of soil bacteria exist, a culturable-dominant and a culturable-non-dominant. The culturable-dominant assemblage remained relatively stable throughout the seasonal changes and during the precipitation event of August 2006 and consisted largely of bacterial species of the Arthrobacter and Burkholderia genus. However, the culturable-non-dominant assemblage responded to seasonal changes by either increasing or decreasing in population density and increased in density during the precipitation event. The responses observed in the culturable-non-dominant assemblage may provide an explanation towards the difficulty many researchers experience in culturing organisms from the environment. Furthermore, culture-dependant techniques proved to be more sensitive in detecting changes in the bacterial community structure than culture-independent based techniques. Also, to aide in the collection of data for the second study, computer software was developed using the C# computer language and has been made available at: http://www.biol.ttu.edu/faculty/jzak/dgge_soft.Item Effects of simulated precipitation on nitrogen cycling and microbial processes in a grassland ecosystem at Big Bend National Park, Texas(Texas Tech University, 2003-12) Nagy, Amber MelanieVariations in the timing and magnitude of precipitation events have the potential to influence microbial dynamics and subsequent ecosystem level processes on a variety of scales leading to irreversible changes in vegetation structure and composition. According to the Hadley Climate Change Model #2, the Big Bend region of far west Texas is expected to receive 25% more precipitation in both the winter and summer months. The effects of changes in precipitation amounts and timing on nitrogen dynamics and microbial processes in the Sotol-grasslands at Big Bend National Park were studied. The objectives for this thesis were to: (1) monitor changes in soil nitrogen dynamics in response to variations in precipitation timing and amounts, (2) evaluate impacts of increased precipitation on soil microbial dynamics, and (3) examine, using a greenhouse experiment, the impacts of rainfall pH on soil nitrogen dynamics and microbial biomass production. The field experimental site was in the Sotol-grasslands along the Pine Canyon Watershed at Big Bend National Park, Dominant species plots, containing either Side-Oats grama, Sotol, or Brownspined Prickly-Pear cacti, and also community plots containing all three plant species, were established to examine the impacts of additional precipitation on soil microbial and nitrogen dynamics. Four water treatments (control, summer water only, winter water only, and summer and winter water) were applied beginning in January 2002. Winter water treatments were applied once during the winter season and summer watering took place over three different watering events. Additional water amounts were determined during the first year of the experiment by adding an additional 25% of the past 100 years precipitation averages. During the second year of the experiment, additional moisture was an additional 25%. of the previous three months' precipitation. This approach accounted for yearly precipitation variation. Plant type and season of water addition influenced the rate of N-mineralization, N-mineralization rates in the dominant species plots were significantly different among dates during the winter and spring, but not during the summer and warmer periods of the year. Plots with Side-Oats grama experienced the highest average rate of N-mineralization across date while Sotol plots had the lowest average rate of mineralization. Across the two years, ammonification rates were positive during the ApriI-June (2002) sample dates in all treatments and after the summer and winter watering events. For the remainder of the sampling periods, ammonification rates were negative. The negative rates are indicative of NH4+-N loss through either plant uptake and/or the process of nitrification. An increase in nitrification across plant types was found during the spring months and also early autumn months. The increase in nitrification rates does not appear to be directly related to water addition, but is a seasonal interaction for both the single species and community plots. Microbial biomass carbon production was directly related to soil moisture in that, for both plot types, plots watered in both the summer and winter contained the largest amounts of microbial biomass on average over the duration of the experiment. In the dominant species plots, vegetation type had a direct impact on the amounts of microbial biomass carbon and the levels of extractable NH4+-N and extractable NO3- -N contained within the plots. In the greenhouse experiment using soil from the Sotol-grasslands treated with water of varying pH's to simulate acid rain, it was found that water addition initially stimulated the release of immobilized or otherwise unavailable nitrogen, thereby allowing that nitrogen to become available for N-mineralization, It was also found that, like the field study at the Sotol-grasslands, nitrification is the primary contributor in N-mineralization, Microbial biomass carbon amounts were found to increase when treated with water pH 4,5, but levels of microbial biomass carbon declined initially when treated with water at pH at 3.5 and 5, The increase may be attributed to an increase in bacterial and fungal activity resulting from the changes in soil conditions, namely nitrogen and water availability, in response to acidic precipitation. Together, the field and greenhouse results suggest that alteration in precipitation patterns and amounts coupled with changes in rainfall chemistry as a result of pollution will have significant impacts on soil microbial activity and subsequently nitrogen dynamics in a complex manner within the Sotol grasslands at Big Bend National Park,.Item Fungal functional diversity: exploring patterns and processes associated with soil fungal assemblages along an altitudinal gradient in the Chihuahuan Desert(Texas Tech University, 2002-05) Sobek, Edward AndrewSoil fungi are intimately associated with the maintenance and stability of terrestrial ecosystems through their involvement in the decomposition process. During decomposition, organic carbon is mineralized to CO2 and bound nutrients are returned to the labile soil nutrient pool for subsequent growth of plants and soil microbes. To better understand the relationship between soil fungal diversity, and factors influencing their functional ability in the decomposition of soil organic matter, this dissertation examined, (1) development of methods to determine soil fungal functional diversity, (2) seasonal trends in fungal function al diversity, and (3) the relation between soil fungal functional abilities and a suite of environmental variables that are important in ecosystem nutrient cycles. The context of this research endeavor focused on assemblages of soil fungi associated with an environmental gradient in the Chihuahuan Desert, specifically, the Pine Canyon Watershed in Big Bend National Park. The Pine Canyon Watershed contains five distinct vegetation zones along an altitudinal gradient and contains the majority of vegetation types that are found in the Chihuahuan Desert. Soil samples were collected within each of these zones over a three-year period. Sampling coincided with seasonal changes in temperature and precipitation. Functional diversity was determined for fungal assemblages from each vegetation zone, using the Soil FungiLog procedure developed from this research.Item Micropaleontology of lower portion of Boquillas Formation near Hot Springs, Big Bend National Park, Brewster County, Texas(Texas Tech University, 1960-05) Huffman, Marion EdwardThe Boquillas Formation, continuously exposed near Boquillas in Big Bend National Park in southeastern Brewster County, has been measured, sampled, and described by the writer. The contained microfossils have been identified to species, and a key to their identification has been constructed as an aid to future workers. The Boquillas Formation, previously divided into two unnamed members by workers from the Bureau of Economic Geology of The University of Texas, is correlated with the Britton and Arcadia Park Formations of the Eagle Ford Group in Central Texas. Paleoecologic factors and physical evidences have been used to determine the theoretical environment of deposition of the Boquillas Formation. The findings indicate that the formation consists of rocks deposited in a transgressive sea.Item Seasonal and nightly activity of Mexican long-nosed bats (Leptonycteris nivalis) in Big Bend National Park, TexasAdams, Erin .; Ammerman, Loren K; Negovetich, Nicholas J; Guardiola, Amaris R; Jones, Laurence FThe seasonality and activity of endangered Mexican long-nosed bats (Leptonycteris nivalis) was studied by Passive Integrated Technology (PIT) tagging in Big Bend National Park, Texas. Activity of 79 bats (out of 104 total tagged bats) at Mount Emory Cave was monitored via a serpentine antenna from 26 April – 1 September 2014 and 16 June – 19 August 2015. First year return rates included 42% adult females, 50% juvenile females, and 8% juvenile males. Cave use varied by demographic; on average juvenile males were active over longer duration each night (p<0.01) and greater range of dates (p<0.02) than lactating females. The most detections of bats occurred in the morning hours (p<0.005). Individuals were present for an average of 13.9 nights (±10.3, range: 1-39). Since some tagged individuals return to the cave annually, apparent survival and redetection probabilities can be generated for this colony over time and improve our understanding of this species.Item The structural evolution of the McKinney Hills Laccolith, Big Bend National Park, Texas(2007-05) Martin, David M.; Yoshinobu, Aaron S.; Leverington, David; Lehman, ThomasMultiple tectonic events are recorded in the McKinney Hills, Big Bend National Park, TX. The region is underlain by Cretaceous through Eocene shallowly southwest dipping-limestones, sandstones, and shales, intruded by a 9 km by 3 km Oligocene-age alkali feldspar quartz syenite laccolith-sill complex. Detailed mapping, kinematic analysis of brittle faults, and analysis of ASTER/aerial orthoimages were used to discriminate structures into different tectonic events and evaluate pluton construction as well as discriminate gross lithologies. High angle-reverse faults, open folds, and monoclines trending N-NW characterize the oldest structures. West of the structural aureole of the intrusion, these open folds are attributed to regional Late Cretaceous-Early Tertiary Laramide contraction seen elsewhere in the park. Intrusion of augite-hornblende-fayalite composite alkali feldspar quartz syenite occurred by multiple emplacement mechanisms. Concordant host rock doming occurred on the W- and NW- margins. The W-margin is defined by discordant contacts and 'fingers' protrude from the main intrusion at km- to m-scales. A flat, shallowly-west-dipping floor of the intrusion is exposed on the E-margin. NW-trending Mode I and high-angle normal oblique faults characterize the youngest structures in the area and are ascribed to regional Miocene Basin and Range extension. Field evidence indicates that the intrusive suite was emplaced by a series of inflated sills and connecting risers ascending and propagating along N-trending, preexisting Laramide structures. Along the NW margin, the intrusion concordantly intruded bedding planes of the Pen Formation and lifted Upper Cretaceous through Eocene overburden forming a laccolith geometry. Discordant intrusion-host rock contact relationships occur along the western and southern margins. Exposures display host rock xenoliths incorporated into the intrusion, discordant bedding planes cut by the intrusion, local magmatic breccias, and intrusive 'fingering' at map to outcrop scales. Mechanical modeling indicates the laccolith was emplaced at a near neutrally buoyant level and magma overpressure, on the order of 32 MPa, was used to lift a maximum of 1400 meters of overburden. These results indicate that laccolith formation elevation and form in the Big Bend region may strongly be controlled by buoyancy and not local horizontal anisotropies. Results also indicate that magmatism may in part be focused along pre-existing structures. A comparison of fingered sheet peripheries at the Shonkin Sag laccolith, Montana and Henry Mts., Utah with McKinney Hills finger forms is attributed to not only viscosity contrasts with magma and host rocks as Pollard (1975) suggested, but the length of time which the magma has to crystallize.Item Understanding nitrogen and microbial dynamics associated with two degraded grassland systems in Big Bend National Park(Texas Tech University, 2004-12) Resinger, Jennifer SueDesertification is responsible for diminishing land productivity in the Chihuahuan Desert and over much of the southwestern United States. Current research indicates that the ongoing degradative loss of land productivity globally will increase as the human population continues to grow and as these systems undergo climatic changes (i.e., precipitation,temperature). The ongoing effects of desertification of formally productive grasslands, as evidenced by nitrogen dynamics and microbial processes in the Dog Canyon and Airport sites at Big Bend National Park were determined in this investigation. The objectives for this thesis were to: (1) determine seasonal patterns in soil nitrogen (extractable NH4-N and extractable NO3-N) and N-mineralization in intact versus fragmented Tabossa grass {HHaria mutica) areas in Big Bend N.P., and (2) examine the relationship between grassland fragmentation dynamics and seasonal variations in microbial biomass dynamics. The field experimental sites were located in the northernmost part of Big Bend National Park. The Dog Canyon and Airport sites were established to examine and compare microbial and nitrogen dynamics in vegetated versus bare soil areas of desertified grasslands. Soils in both sites are classified as Chalkdraw with Tabossa grass as the dominant plant species. Soils were collected from both sites during February, April, June, August, October, and December 2003, and February, April, and June 2004. Upon collection, soil samples were analyzed for soil moisture, microbial biomass, available and extractable nitrogen, net N-mineralization, soil organic matter and soil pH.