West-central Texas Research Articles

ASSESSING THE NEEDS OF OLDER ADULTS IN RURAL WEST TEXAS

Abstract With 1 in 5 adults over the age of 65 living in rural areas, understanding their unique concerns and needs becomes increasingly important. This study was carried out in partnership with the West Central Texas Area Agency on Aging (WCT AAA) to identify the top concerns of older adults in rural West Texas. The survey was conducted in person at four locations across the region served by the WCT AAA. A total of 183 respondents completed the survey and their responses to the question “what are the biggest issues facing older adults today” along with demographic information were collected. Participants were between the ages of 56 and 95 years old with a mean age of 76 years old. 60% of the participants were female and 40% were male. Respondents were predominantly White, 80%, with 16% Hispanic or Latino, and 3% Black or African American. The most common concern among respondents was physical health and well being with the increasing cost of living being the second most frequent response. Additionally, residents from more rural counties reported social interaction as more important than either health or cost of living. These findings highlight the need for targeted interventions to address the concerns of older adults in rural areas, particularly related to healthcare access and social isolation. Strategies such as telemedicine and community-based programs to address transportation and social isolation may be particularly effective in addressing these concerns.

Interactions of long-term grazing and woody encroachment can shift soil biogeochemistry and microbiomes in savanna ecosystems

Semi-arid grasslands and savannas in the southern Great Plains USA are extensively used for livestock grazing. Over the past century, Juniperus (juniper) and Quercus (oak) species abundance have increased due to intensive grazing and reduced fire frequency. We investigated the interactions between livestock grazing history (none, moderate, heavy) and vegetation cover (grassland, juniper, oak) using a ∼ 70-year grazing experiment in west-central Texas. We explored effects on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), microbial community composition, and function. SOC and TN were 50–150 % higher under juniper and oak compared to grasslands, and 10–30 % lower in grazed vs. ungrazed areas. Vegetation × grazing interaction showed greater SOC and TN loss under oak than juniper or grasslands. Ungrazed controls had higher soil TP than grazed areas, with oak and juniper soils having more TP than grasslands. Bacterial and fungal communities differed between grassland and woody vegetation. Grazing affected only bacterial communities. SOC, TN, TP accounted for differences in community structure. Abundances of genes related to methane, nitrogen, sulfur metabolisms, and dominant fungal trophic modes were linked to soil C, N, P ratios. These findings highlight how long-term livestock grazing and woody plant encroachment influence soil C, N, P cycles, altering soil microbial community structure and function. This study provides insights for savanna ecosystem management and integrating land cover effects into biogeochemical models for global change scenarios.

An Analysis of Northward-Moving Tornadoes within an Open Warm Sector Across Eastern Texas

Tornadoes in eastern Texas generally track to the east as predominant westerly upper flow acts on their parent storms. However, an examination of tornadoes from 2000 to 2018 finds that 22% of all tornadoes in the region move in much more northward directions. These tornadoes’ parent storms develop in the open warm sector prior to the arrival of a main linear forcing mechanism (e.g., front, dryline). In fact, some of the more notable tornado outbreaks in recent years across Texas have occurred from northward-moving thunderstorms. This bifurcation of storm/tornado motions is important to understand for forecasting, warning, and messaging of these events. The results show these tornadoes typically occur eastward of large, slow moving, mid to upper-level long-wave troughs and underneath the left quadrant exit-region of an upper-level jet streak. The composite pattern also shows that a low-level jet in eastern Texas, a surface low centered in west-central Texas, and a warm/stationary front extending northeast of the surface low were common for these events. The typical air mass was indicative of weak instability, low convective inhibition, and high shear. Radar analysis of the northerly moving, tornadic storms showed mesocyclonic circulations with smaller diameters and lower rotational shear when compared with tornadic storms that moved in an easterly direction.

Risk Assessment of Future Climate and Land Use/Land Cover Change Impacts on Water Resources

Climate and land use and land cover (LULC) changes will impact watershed-scale water resources. These systemic alterations will have interacting influences on water availability. A probabilistic risk assessment (PRA) framework for water resource impact analysis from future systemic change is described and implemented to examine combined climate and LULC change impacts from 2011–2100 for a study site in west-central Texas. Internally, the PRA framework provides probabilistic simulation of reference and future conditions using weather generator and water balance models in series—one weather generator and water balance model for reference and one of each for future conditions. To quantify future conditions uncertainty, framework results are the magnitude of change in water availability, from the comparison of simulated reference and future conditions, and likelihoods for each change. Inherent advantages of the framework formulation for analyzing future risk are the explicit incorporation of reference conditions to avoid additional scenario-based analysis of reference conditions and climate change emissions scenarios. In the case study application, an increase in impervious area from economic development is the LULC change; it generates a 1.1 times increase in average water availability, relative to future climate trends, from increased runoff and decreased transpiration.

Simulating impacts of real-world wind farms on land surface temperature using the WRF model: physical mechanisms

A recent study shows that the current wind turbine parameterization in the weather research and forecasting (WRF) model can generally reproduce the satellite observed nighttime warming signal over wind farm (WF) regions over west central Texas, but also tends to produce a cooling effect in the WF downwind regions. The present study conducts a series of WRF simulations to further this research by addressing two fundamental questions: (i) what is the 3-D structure of simulated near-surface temperatures within and around WFs? (ii) what are the main physical mechanisms responsible for the simulated WF-induced temperature changes? Our results indicate that the WF-induced temperature changes are not only restricted to the surface but also can extend vertically to the hub-height level and horizontally in the downwind direction. The WF-induced change in sensible heat flux is the dominant factor for the simulated temperature changes at the surface, for both the warming signals over the WF region and the cooling signals behind it. Further diagnosis shows that the turbulent component of the wind turbine parameterization is responsible for the surface warming signal by enhancing vertical mixing while the momentum sink component is responsible for the surface cooling signal by enhancing near-surface thermal stratification. By analyzing the energy budget, we find two important physical processes that are critical to explain the simulated WF impacts on temperature: (i) vertical divergence of heat flux as parameterized in the planetary boundary layer scheme and (ii) resolved-scale 3-D temperature advection.

A geospatial study of the drought impact on surface water reservoirs: study cases from Texas, USA

Satellite images have been used historically to measure and monitor fluctuations in the surface water reservoirs. This study integrates remote sensing and Geographic Information System (GIS) technologies to investigate the impact of drought on 10 selected surface water reservoirs in San Angelo and Dallas, Texas. Oscillations in summer and winter months throughout the 2005–2016 period were assessed using multispectral images from Landsat-5, −7, and −8, and changes in the reservoirs were characterized and correlated against local climate data of each reservoir. For quantitative comparisons of the time-series measurements, a robust density slicing approach was employed to classify the range of values of the raster cells in the near-infrared band of Landsat images for each lake into three desired classes (deep water, shallow water, and dry area) based on the natural breaks inherent in the dataset. Statistical analysis shows that the overall accuracy of the classification is about 94%, which demonstrates the efficiency of the density slicer to accurately estimate surface water area changes from an individual Landsat band. Shrinkage in the surface water area over the study period reveals the concrete impact that the drought along with other factors have on the 10 selected lakes. The San Angelo lakes located in west central Texas experienced a nearly consistent pattern of change during most of the study period; whereas the Dallas lakes in northeast Texas followed the oscillating pattern of drought and correlated closely to the local conditions. Shockingly, the extreme drought caused complete vanishing of several lakes, and consequently Texas had to remove them from its recreational plans. Our new findings can certainly help with the water resource management in Texas and our study approach can be adapted for monitoring lake oscillations in other areas across the world. This geospatial study demonstrates the societal benefits from incorporating remote sensing and GIS in investigating geo-environmental problems associated with severe climate changes.

Species delimitation in endangered groundwater salamanders: Implications for aquifer management and biodiversity conservation

Groundwater-dependent species are among the least-known components of global biodiversity, as well as some of the most vulnerable because of rapid groundwater depletion at regional and global scales. The karstic Edwards-Trinity aquifer system of west-central Texas is one of the most species-rich groundwater systems in the world, represented by dozens of endemic groundwater-obligate species with narrow, naturally fragmented distributions. Here, we examine how geomorphological and hydrogeological processes have driven population divergence and speciation in a radiation of salamanders (Eurycea) endemic to the Edwards-Trinity system using phylogenetic and population genetic analysis of genome-wide DNA sequence data. Results revealed complex patterns of isolation and reconnection driven by surface and subsurface hydrology, resulting in both adaptive and nonadaptive population divergence and speciation. Our results uncover cryptic species diversity and refine the borders of several threatened and endangered species. The US Endangered Species Act has been used to bring state regulation to unrestricted groundwater withdrawals in the Edwards (Balcones Fault Zone) Aquifer, where listed species are found. However, the Trinity and Edwards-Trinity (Plateau) aquifers harbor additional species with similarly small ranges that currently receive no protection from regulatory programs designed to prevent groundwater depletion. Based on regional climate models that predict increased air temperature, together with hydrologic models that project decreased springflow, we conclude that Edwards-Trinity salamanders and other codistributed groundwater-dependent organisms are highly vulnerable to extinction within the next century.

BERMUDAGRASS (CYNODON DACTYLON) RESPONSE TO SUMMER PRESCRIBED BURNING

Abstract Bermudagrass (Cynodon dactylon (L.) Pers.) is one of the principle hay and forage crops throughout Texas. However, maintaining the productivity of those pastures can be challenging due to high input costs such as fertilizer and herbicide. To offset fertilizer costs and increase vegetative reproduction of bermudagrass stands, a summer prescribed burn was implemented on an irrigated bermudagrass pasture in west-central Texas. Summer fires took place on 30 July 2015 near San Angelo, Texas. Soil response to burning was measured using plant root simulator probes (PRS Western Technologies) to determine the belowground effects of a hot summer prescribed burn. Vegetative reproduction of bermudagrass was assessed by determining active, dormant, and dead vegetative buds on bermudagrass tillers. Forage quality of bermudagrass hay samples were also assessed to determine prescribed burn effects. Prescribed burning was beneficial to bermudagrass irrigated pasture. Bioavailable nitrogen (N), calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and sulphur (S) increased following the prescribed burn compared to the non-burned control. Burned bermudagrass had increased bud bank activity and density compared to non-burned controls. Forage analysis also showed positive responses to prescribed burning with increases in crude protein (cp), total digestive nutrients (TDN), K, and Ca in hay forage samples compared to samples taken from non-burned controls. Prescribed burning presents a positive, inexpensive alternative to fertilizer on irrigated bermudagrass pastures. Prescribed burning offers both below-and aboveground positive effects through increased forage quality, soil fertility, and vegetative reproductive buds of bermudagrass.

New occurrence records for stygobiontic invertebrates from the Edwards and Trinity aquifers in west-central Texas, USA

We report new occurrence records for stygobiontic invertebrates from the Edwards and Trinity aquifers in Blanco, Hays, and Travis counties of central Texas, USA. Our collection includes seven species from four families: Caecidoteareddelli (Steeves, 1968), Asellidae; Crangonyxnr.pseudogracilis Bousfield, 1958, Stygobromusbalconis (Hubricht, 1943), Stygobromusbifurcatus (Holsinger, 1967), and Stygobromusrusselli (Holsinger, 1967), Crangonyctidae; Sphalloplanamohri Hyman, 1938, Kenkiidae; and Cirolanides sp., Cirolanidae. Specimens of Caecidoteareddelli and Crangonyxnr.pseudogracilis are new records for Hays County and Travis county, respectively. Specimens of an undescribed species of Cirolanides were collected from a well in Hays County and from two localities in Travis County.

An Emerging Geography of the Agrarian Question: Spatial Analysis as a Tool for Identifying the New American Agrarianism

AbstractKarl Kautsky’s Agrarian Question remains a useful lens for analyzing the relationship between small and large agricultural producers under the conditions of industrial capitalism. The U.S. agricultural census provides an opportunity to identify socioeconomic, demographic, and agricultural factors associated with new and alternative farming at the county level, and then analyze these for spatial patterns within a geographic information system. By associating these county‐level indicators with a crowd‐sourced USDA directory of farmers’ markets as a proxy for local demand, we identified four hot spots of new American agriculture: The West Coast, central Texas and Oklahoma, central Florida, and the Great Lakes region. Furthermore, we show that these areas have been growing since 1997. An additional farmer hot spot in central Appalachia diminished after 1997 and finally disappeared in 2012. We argue that spatial analysis is a tool for defining new agrarian landscapes, observing geographic and social shifts in small, alternative farming, and conducting more focused ethnographic research.

Common Rangeland Plants of West Central Texas by George Clendenin, USDA–Natural Resources Conservation Service

Common Rangeland Plants of West Central Texas by George Clendenin, USDA–Natural Resources Conservation Service

Simulating Impacts of Real-World Wind Farms on Land Surface Temperature Using the WRF Model: Validation with Observations

This study simulates the impacts of real-world wind farms on land surface temperature (LST) using the Weather Research and Forecasting (WRF) Model driven by realistic initial and boundary conditions. The simulated wind farm impacts are compared with the observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the first Wind Forecast Improvement Project (WFIP) field campaign. Simulations are performed over west-central Texas for the month of July throughout 7 years (2003–04 and 2010–14). Two groups of experiments are conducted: 1) direct validations of the simulated LST changes between the preturbine period (2003–04) and postturbine period (2010–14) validated against the MODIS observations; and 2) a model sensitivity test of LST to the wind turbine parameterization by examining LST differences with and without the wind turbines for the postturbine period. Overall, the WRF Model is moderately successful at reproducing the observed spatiotemporal variations of the background LST but has difficulties in reproducing such variations for the turbine-induced LST change signals at pixel levels. However, the model is still able to reproduce coherent and consistent responses of the observed LST changes at regional scales. The simulated wind farm–induced LST warming signals agree well with the satellite observations in terms of their spatial coupling with the wind farm layout. Moreover, the simulated areal mean warming signal (0.20°–0.26°C) is about a tenth of a degree smaller than that from MODIS (0.33°C). However, these results suggest that the current wind turbine parameterization tends to induce a cooling effect behind the wind farm region at nighttime, which has not been confirmed by previous field campaigns and satellite observations.

Initial Effects of Prescribed Burning on Survival and Nesting Success of Northern Bobwhites in West-Central Texas

Fire is often prescribed for managing habitat for northern bobwhites (Colinus virginianus) in the southeastern United States, yet little is known about its use as a tool in more xeric portions of the species’ range. This study was conducted from 1994 to 1995 on 3 sites in the northern Edwards Plateau ecoregion of Texas to monitor immediate post-burn effects on bobwhite ecology. Each site included a burned pasture paired with an unburned control. We radiomarked >= 50 bobwhites (25/pasture) at each study site with neck-loop transmitters just prior to burning and monitored their survival and nesting habits for 6 months post-burn. Survival was similar (P > 0.05) between burned and unburned areas. Predation was the leading cause of mortality, with mammals and raptors accounting for 68% and 31% of the predation, respectively. Nest initiation and success were low for both treatments. Nest sites occurred mostly in association with prickly pear cactus (Opuntia spp.). Our results suggest that relatively ‘‘cool’’ prescribed burns had few short-term effects on bobwhite survival in west-central Texas. However, reductions in cacti density and cover that often occur post-burn, especially if followed by an application of herbicide (i.e., picloram), may reduce the number of potential nesting sites for bobwhites.

Persistence of a Severe Drought Increases Desertification but not Woody Dieback in Semiarid Savanna

Increases in precipitation variability, coupled with higher temperatures, will lead to greater frequencies of severe, prolonged droughts for many regions with the expectation of attendant increases in woody plant die-off events. We took advantage of a 2-yr extension of a severe drought following an initial study of woody plant dieback in a woody-encroached semiarid savanna in west-central Texas, United States. This study tests for the emergence of alternative vegetation trajectories as a result of continued drought persistence: 1) whether additional woody plant dieback occurred following the initial study, leading to a grass-dominated community, or 2) whether desertification became a major feature (defined as a loss of herbaceous cover and increase in bare ground). Neither the emergence of a grass-dominated community nor the prevalence of desertification was observed during the initial study. After 2 additional yr of drought, we found that dieback of woody plants did not increase above previously observed levels, suggesting that the prolongation of drought did not cause the emergence of a grass-dominated community in this heavily encroached rangeland. However, drought severity did lead to increases in desertification, with increases in bare ground owed to declines in grass cover. While previous research at this long-term research site suggests that desertification is transient with grasses rebounding once precipitation returns to predrought levels, rangeland managers should be aware of lags in vegetation response to drought and the increased potential for a shift toward a bare-ground dominated community following extended extreme drought. In this Texas semiarid savanna, major losses in herbaceous cover lagged behind woody plant dieback, so dieback of the woody component might hold promise as an indicator for near-term potential of desertification.

Weaving the world of the ancestors: Early incised stones from the Kincaid Shelter in west Central Texas

Incised stones recovered from the Kincaid Shelter in west Central Texas are the focus of inquiry in this paper. Despite the inherent problems in interpretation of the portable forms, I utilize multiple lines of information gathered from diverse sources to inform the ideas presented here. I provide detailed evidence to support my conclusion that the imagery incised on the stones depicts weaving techniques (twining, plaiting, cordage motifs, and netting). The additional presence of an incised orb spider web on some stones echoes its metaphoric relationship to weaving and the female spider's role in the myths and legends of North America. The context of the incised stones in the Kincaid rock shelter provides support for a plausible explanation that women, typically the producers of woven items such as baskets and mats in many North American cultures, were the creators of the Kincaid incised stones. I discuss the difficulty in discovering meaning across time and place and propose that the incised imagery was not an end product in itself. Rather it represents a visual dialog to stimulate recall and evocation of ancestral stories or myths to expand, explore, or reinforce the well-being of the Kincaid people in some way.

TyphloelmisBarr (Coleoptera: Elmidae: Elminae), a New Stygobiontic Riffle Beetle Genus with Three New Species from Texas, USA

Abstract The adult and larva of Typhloelmis Barr, a new genus of eyeless, stygobiontic elmid from springs in west-central Texas, and the adults of three new species, Typhloelmis caroline Barr, Typhloelmis finegan Barr, and Typhloelmis sanfelipe Barr, are described, diagnosed, and illustrated. Taxonomic couplets are provided for the insertion of the new genus into existing adult elmid generic keys, and an adult key to the species of Typhloelmis is included. Stygobiontic elmids are reviewed, and the uniqueness of Typhloelmis is discussed. Typhloelmis is the first stygobiontic elmid genus reported from the Nearctic ecozone and is the seventh described worldwide. It is only the second elmid genus known to be anophthalmic (completely eyeless). The Edwards-Trinity Aquifer and the spring habitat in which the genus and species occur are described in detail, and potential threats are discussed.

Spatial Organization and Home Range Patterns of the American Hog-nosed Skunk (Conepatus leuconotus)

Abstract The American hog-nosed skunk (Conepatus leuconotus) is an understudied mesocarnivore for which no extensive ecological studies have been conducted. We radio-collared 29 skunks (15 male, 14 female) at a site in west-central Texas, U.S.A. and used data from 14 (5 male, 9 female) to determine patterns of home range and spatial organization. Home range (95% fixed kernel) of males averaged three times that of females (1.9 km2 vs. 0.64 km2) and extensive intrasexual and intersexual overlap in home ranges was documented. Female home ranges and core areas differed significantly in their topography (changes with which were associated with habitat difference) from those of males. Home range sizes were correlated with body size and gender, but intersexual differences between home range sizes and their topography indicate space-use patterns between male and female American hog-nosed skunks are influenced by factors beyond metabolic requirements alone. Specifically, we believe male home ranges are large to ma...

Wheelerodemus muhlenbergiae, a New Genus and New Species of Blissidae (Hemiptera: Heteroptera: Lygaeoidea) from Oklahoma and Texas

Abstract. The new blissid genus Wheelerodemus is described to accommodate the new species W. muhlenbergiae, based on specimens collected on the grasses Muhlenbergia lindheimeri and M. reverchonii from the Arbuckle Mountains in southcentral Oklahoma and the Edward's Plateau in westcentral Texas. Because the size of specimens from Oklahoma appeared consistently smaller than those from Texas, samples from each area were sequenced using the COI barcode region to help determine that only one variable species was involved. Diagnoses, descriptions, a color habitus illustration of the adult male, dorsal and lateral photographs of the adult male and female, photomicrographs of selected structures, illustrations of male and female genitalia, and a key to the U.S. blissid genera are provided to help distinguish this new genus and species from other Blissidae.

A case study of effects of atmospheric boundary layer turbulence, wind speed, and stability on wind farm induced temperature changes using observations from a field campaign

Recent studies using satellite observations show that operational wind farms in west-central Texas increase local nighttime land surface temperature (LST) by 0.31–0.70 °C, but no noticeable impact is detected during daytime, and that the diurnal and seasonal variations in the magnitude of this warming are likely determined by those in the magnitude of wind speed. This paper further explores these findings by using the data from a year-long field campaign and nearby radiosonde observations to investigate how thermodynamic profiles and surface–atmosphere exchange processes work in tandem with the presence of wind farms to affect the local climate. Combined with satellite data analyses, we find that wind farm impacts on LST are predominantly determined by the relative ratio of turbulence kinetic energy (TKE) induced by the wind turbines compared to the background TKE. This ratio explains not only the day–night contrast of the wind farm impact and the warming magnitude of nighttime LST over the wind farms, but also most of the seasonal variations in the nighttime LST changes. These results indicate that the diurnal and seasonal variations in the turbine-induced turbulence relative to the background TKE play an essential role in determining those in the magnitude of LST changes over the wind farms. In addition, atmospheric stability determines the sign and strength of the net downward heat transport as well as the magnitude of the background TKE. The study highlights the need for better understanding of atmospheric boundary layer and wind farm interactions, and for better parameterizations of sub-grid scale turbulent mixing in numerical weather prediction and climate models.

Effects of Topography on Assessing Wind Farm Impacts Using MODIS Data

Abstract This paper uses the empirical orthogonal function (EOF) analysis to decompose satellite-derived nighttime land surface temperature (LST) for the period of 2003–11 into spatial patterns of different scales and thus to identify whether (i) there is a pattern of LST change associated with the development of wind farms and (ii) the warming effect over wind farms reported previously is an artifact of varied surface topography. Spatial pattern and time series analysis methods are also used to supplement and compare with the EOF results. Two equal-sized regions with similar topography in west-central Texas are chosen to represent the wind farm region (WFR) and nonwind farm region (NWFR), respectively. Results indicate that the nighttime warming effect seen in the first mode (EOF1) in WFR very likely represents the wind farm impacts due to its spatial coupling with the wind turbines, which are generally built on topographic high ground. The time series associated with the EOF1 mode in WFR also shows a persistent upward trend over wind farms from 2003 to 2011, corresponding to the increase of operating wind turbines with time. Also, the wind farm pixels show a warming effect that differs statistically significantly from their upwind high-elevation pixels and their downwind nonwind farm pixels at similar elevations, and this warming effect decreases with elevation. In contrast, NWFR shows a decrease in LST with increasing surface elevation and no warming effects over high-elevation ridges, indicating that the presence of wind farms in WFR has changed the LST–elevation relationship shown in NWFR. The elevation impacts on Moderate Resolution Imaging Spectroradiometer (MODIS) LST, if any, are much smaller and statistically insignificant than the strong and persistent signal of wind farm impacts. These results provide further observational evidence of the warming effect of wind farms reported previously.