Southwest Nebraska Research Articles

Drought affects sex ratio and growth of painted turtles in a long-term study in Nebraska

Climate forecasts suggest the Great Plains of North America have increased risk of droughts during global warming. Environmental factors have potential to influence turtle populations in aquatic habitats through temperature-dependent sex determination and influences on food availability. Long-term studies are critical to evaluate the influence of climatic variation on turtles. We used a 12-year set of mark-recapture data collected from painted turtles (Chrysemys picta, n = 162) in a pond in Keith County, Nebraska during 2005–2016 to assess variation in sex ratio and growth dynamics. Southwest Nebraska experienced two periods of drought during our study (Palmer Hydrologic Drought Index [PHDI] range: -4.5 to 6.7). Despite a relatively stable depth of water in our study pond, the proportion of males in the second size class (carapace length 95–130 mm) decreased when the PHDI during their incubation period indicated hotter, drier conditions. Discrete, mean annual growth (G) of females >30 mm below asymptotic carapace length was greater during wetter years (Gnon-drought = 15.0, Gdrought = 11.5), and a drought coefficient (D) in our modified von Bertalanffy model reflected reduced growth of both males (D = -0.0226) and females (D = -0.0393) during drought years. Our long-term research provides context to the complexity by which turtle species may respond to changes in long-term climate conditions.

The influence of a severe reservoir drawdown on springtime zooplankton and larval fish assemblages in Red Willow Reservoir, Nebraska

Reservoirs can be dynamic systems, often prone to unpredictable and extreme water-level fluctuations, and can be environments where survival is difficult for zooplankton and larval fish. Although numerous studies have examined the effects of extreme reservoir drawdown on water quality, few have examined extreme drawdown on both abiotic and biotic characteristics. A fissure in the dam at Red Willow Reservoir in southwest Nebraska necessitated an extreme drawdown; the water level was lowered more than 6 m during a two-month period, reducing reservoir volume by 76%. During the subsequent low-water period (i.e., post-drawdown), spring sampling (April–June) showed dissolved oxygen concentration was lower, while turbidity and chlorophyll-a concentration were greater, relative to pre-drawdown conditions. Additionally, there was an overall increase in zooplankton density, although there were differences among taxa, and changes in mean size among taxa, relative to pre-drawdown conditions. Zooplankton assemblage composition had an average dissimilarity of 19.3% from pre-drawdown to post-drawdown. The ratio of zero to non-zero catches was greater post-drawdown for larval common carp and for all larval fishes combined, whereas we observed no difference for larval gizzard shad. Larval fish assemblage composition had an average dissimilarity of 39.7% from pre-drawdown to post-drawdown. Given the likelihood that other dams will need repair or replacement in the near future, it is imperative for effective reservoir management that we anticipate the likely abiotic and biotic responses of reservoir ecosystems as these management actions will continue to alter environmental conditions in reservoirs.

A temperature-limited assessment of the risk of Rift Valley fever transmission and establishment in the continental United States of America

The rapid spread of West Nile virus across North America after its introduction in 1999 highlights the potential for foreign arboviruses to become established in the United States of America. Of particular concern is Rift Valley fever virus (RVFV), which has been responsible for multiple African epidemics resulting in death of both humans and livestock, as well as major economic disruption due to livestock loss and trade restrictions. Modern globalization, travel, and commerce allow viruses to easily jump from one continent to another; and it is likely only a matter of time before RVFV reaches North American shores. We used a degree-day model in combination with livestock population data and a pathways analysis to identify regions and times where RVFV is most likely to enter and become established in the United States of America. Transmission risk of the disease varies across the country from 325 annual risk days in parts of Florida to zero risk days in the far North and in high mountain regions. Areas of particular concern are where there are a high number of possible tranmission days, a large livestock population, and proximity to likely locations for the disease to enter the country via mosquito vector or human host. These areas should be monitored closely during transmission "risk seasons" so that if the virus does enter the country and begins to become established, it can be quickly controlled and eliminated before spreading further. Areas most at risk include the Baltimore and New York City metro areas as well as much of the region between these urban centers; most of Texas, especially around Houston; Florida; Atlanta; southwest Nebraska; southern California and Arizona; and the central valley of California.

Source Determination of an Obsidian Projectile Point from the Massacre Canyon Site (25HK13), A Keith Phase Occupation in Southwest Nebraska and Implications for Social Connections During the Early Ceramic Period

The use of chemical analyses to determine the sources of obsidian in central Plains Early Ceramic sites has potential to illuminate social contacts and patterns of exchange of goods. X-ray fluorescence analysis determined that a diagnostic point from the Massacre Canyon site in southwest Nebraska is made of obsidian from the Valle Grande source of the Jemez Mountains of New Mexico. This adds to the small number of central Plains Early Ceramic obsidian samples and suggests differential source use during that period.

My Life as a Ranch Cowgirl

W hat do ranching, rodeoing, and barrel racing have in common? From the early days, ranch work has involved riding horses to take care of the livestock on the rangelands. The early cowboys were very proud of their skills in roping cattle and riding horses. It was only a short time until the cowboys tested their skills in riding horses and roping against each other. This was the start of the professional rodeo we see today. With some exceptions, men were the primary contestants in rodeo events. Because most rodeo events are relatively dangerous, women were not allowed to compete. It is not hard to see that women also wanted to compete. In 1948, 38 ranch women gathered in San Angelo, Texas, and organized a rodeo association just for women—the Girls Rodeo Association (GRA) was born. It was formed for 2 reasons: 1) to give women legitimate, honest opportunities to compete in all-girl rodeos and 2) to establish an alliance with the Rodeo Cowboy Association (RCA). The GRA board members worked hard to persuade rodeo committees and producers to hold women’s contests according to GRA rules. The Committees were given the option of choosing which event they would hold. Most of the Committee members picked barrel racing. My family has pursued both ranching and professional rodeo since 1885, when my great-great grandparents homesteaded in southwest Nebraska. My papa (Grandpa), C. O., a third-generation rancher, had a passion for training and raising quality quarter horses. His RCA card was number 110, which he kept current until his death in 2001. He dearly loved rodeoing. Due to the size of the ranching and farming operation he and his wife, Elaine, loved to operate, he was not able to travel to compete in rodeos as much as he would have liked. However, in 1955, at the RCA Greeley Stampede rodeo, in Greeley, Colorado, he won his favorite event, calf roping, on a mare named Bald. This makes me think of my mom, Deb. In 1975, 20 years after papa won the calf roping at Greeley, my mom won the GRA barrel race, on a gelding, Bald’s Breeze, a son of Bald. Slipping out to the barn to ride a couple horses papa raised, she developed her training skills on Bald’s Breeze and a three-quarter brother, Bald’s Folly. My Life as a Ranch Cowgirl

Alluvial stratigraphic evidence for channel incision during the Mediaeval Warm Period on the central Great Plains, USA

Alluvial valley fills from tributaries to the upper Republican River, southwest Nebraska, USA, provide soil- and morpho-stratigraphic evidence for an episode of channel incision that occurred between c. 1100 and 800 14C yr BP, based on 11 new radiocarbon ages. This local episode of channel incision correlates with other alluvial stratigraphic studies from the central Great Plains and demonstrates regionally synchronous fluvial behaviour. Proxy records of palaeohydrologic conditions in and around the Great Plains (including lacustrine, aeolian and geomorphological sources) indicate that channel incision correlates with a multicentennial episode of common, widespread drought. Temporally, this drought episode corresponds to the period recognized in many regions as the Mediaeval Warm Period (MWP). Therefore, this research demonstrates: (1) a relationship in the semi-arid central Great Plains between drought and increased fluvial incision; and (2) a local/regional geomorphic response to a particular episode of global climate change.

FIELD SCALE LIMITED IRRIGATION SCENARIOS FOR WATER POLICY STRATEGIES

Approaches to reducing irrigation inputs to crops have been studied for the past 50 to 60 years in research settings. Fewer efforts have been made to document limited irrigation responses over a number of seasons on commercial fields. This study compared farm-based irrigation management (FARM) with best management practices (BMP), late initiation of irrigation (LATE), and a restricted allocation (ALLOC). These irrigation management strategies each occupied 1/8 of a center pivot system in southwest Nebraska in continuous corn production, on four cooperating farms, which were replicated at the same sites for 3 to 6 years. Irrigation variables were achieved by irrigating or not irrigating, or by speeding up or slowing down the center pivot. When the grain yields and irrigation amounts were normalized each year using the FARM treatment as the basis, on average for three of four locations, the BMP treatment yielded equal to the FARM treatment, the LATE treatment yielded 93% of the FARM treatment and the ALLOC yielded 84% of the FARM treatment. At the same time, it took 76% and 57% of the water for the LATE and ALLOC treatments, respectively, to achieve these yields. The adjusted gross returns (yield . price – irrigation treatment costs) of the irrigation treatments were analyzed for each location. When the gross returns were normalized using the FARM treatment as the basis, FARM and BMP returns were equal across combinations of high and low input commodity prices and pumping costs. The LATE treatment gross return was 95% of FARM return. The gross return for the ALLOC treatment was 85% to 91% of the FARM treatment. The higher the water costs, the lower the difference between the highest and lowest returning water treatments. Relationships between evapotranspiration and grain yield were developed for two sites over the limited range of water applications of the projects. Regressions indicated more variability between the commercial field data and research plot environments. Much of this difference may have been due to yearly replication in this study rather than plot-to-plot replication in the research center study. Yield and irrigation data were normalized on the basis of the FARM treatment. Normalized yield – irrigation results over years and locations for three of the four locations showed declining yields as irrigation decreased. The same regression was used to normalize the locations with soil textures from fine sand to sandy loam, which suggested that the three locations behaved similarly with respect to the management treatments.

Stable Carbon Isotope Record of Holocene Environmental Change in the Central Great Plains

Ratios of stable carbon isotopes preserved in soil organic matter record vegetation and climate change and are applicable to the dry environment of the central Great Plains. We sampled two loess sections and one sand sheet swale in southwest Nebraska to study a continuous record of late Pleistocene and Holocene climate change. Carbon isotope (δ13C) data are combined with previously reported and new optically stimulated luminescence (OSL) age control to establish the timing and magnitude of vegetation change. Stratigraphic units studied include the late-Pleistocene Peoria Loess and Brady Soil, Holocene Bignell Loess, and four buried soils within Bignell Loess. Isotope ratios and OSL ages indicate a shift from a C3 to C4 vegetation community during formation of the Brady Soil, reflecting climatic warming spanning the Pleistocene-Holocene transition. By the early Holocene, between 10,100 and 9100 yrs. ago, drought became a persistently recurring feature in the region as indicated by the deposition of Bignell Loess that originated from reworking of devegetated dunes and sand sheet deposits. Periods of rapid loess deposition are marked by an increase in C3 vegetation, which we interpret to indicate vegetation adapted to high rates of landscape disturbance. Conversely, C4 vegetation types dominated during periods of landscape stability and soil formation, when precipitation was sufficient for vegetation to grow on dune fields. We conclude that total annual precipitation and landscape stability are more important factors than seasonality of precipitation and atmospheric CO2 concentration in determining the chronology of C3-C4 vegetation change during the Holocene.

Photograph Dated 1927

This one is of two women when they were little girls, so chastened, they cannot raise their eyes. Sisters, arranged like stair-steps. Rivals, arms around the other's shoulders—her neck. Behind—an open landscape beyond the edge of town, An emptiness known As southwest Nebraska. Outside the frame, Grandfather's house. Alien natives! Are they dressed for trick or treat in broad pantaloons And gauzy shawls, with elfish pointed shoes to turn up tiny feet—? No—churchwomen gave no finery for heathen holidays. Tho' of a sweltering summer mission gifts might be allowed to array wild prairie girls like Punjabi princesses. But dress-up brings no joy. Was this the day when sisters learned One summer was too long? Next year [End Page 5] Click for larger view Figure 1 Original drawing by Lonnie Rosenberg.

Alluvial Fans as Records of Holocene Sediment Yield in the Central Great Plains of Southwest Nebraska

Soils buried by alluvial fan deposits in southwest Nebraska record several intervals of increased sediment yield from small watersheds during the Holocene. These intervals, which began at ca. 9000, 5800, 4000, 3000, and 1000 14C yrs. B.P., were probably caused by some sort of change in regional climatic conditions. Existing evidence of Holocene climate change suggests that increased sediment yields were caused by periodic shifts toward drier climatic conditions, except for the intervals that began at 5800 and 4000 14C yrs. B.P. The cause of increased sediment yields at those times is unclear, although an increased frequency of large intense storms may have been a contributing factor. The record of soil burial exhibits considerable spatial variability both within individual fans and between fans. This is partly due to practical limitations on the number of buried soils that could be sampled on each fan. But it is also due to the inherent spatial variability of depositional processes and to differences in the geomorphic development of the four fans. Thus, researchers who use data from fans to reconstruct sediment-yield histories need to investigate several sites on several fans in order to obtain as complete a record as possible of changing sediment yields.

Dryland Corn vs. Grain Sorghum in Western Kansas

Dryland crop yields in the U.S. Great Plains are limited by low precipitation and high potential evapotranspiration. In western Kansas wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] are grown commonly, whereas corn (Zea mays L.) is believed to lack sufficient drought and heat tolerance for dryland production. A study was conducted near Garden City, KS, from 1991 through 1995 to determine whether corn could be grown successfully. No-till (NT) and conventional-till (CT) corn and grain sorghum were compared. In the driest year, sorghum yielded 137% more than corn with CT and 85% more with NT, but in 3 of 5 yr, NT corn yielded from 34% to 112% more than NT sorghum. In the remaining year, CT sorghum yielded more than CT corn, but NT yields did not differ. Overall, NT increased corn yields by 28% and net return by 69%, but increased sorghum yields by only 11% and had no effect on net return. No-till corn yielded 28% more than NT sorghum and produced 169% more net return, whereas CT corn yielded 11% more than CT sorghum and produced 48% more net return. Dryland corn can be grown in western Kansas if lower yields and returns are accepted in dry years in exchange for yields and returns considerably higher than those of sorghum in favorable years. No tillage will substantially increase yields in most years and is essential to assure adequate corn yields in dry years.

Control of Western Bean Cutworm in Field Corn In Southwest Nebraska, 1985

Abstract Corn test plots were each ca. 30 acres grown under center pivot irrigation. Treatments were applied by a Cessna 188 Husky with a 44 ft wingspan. The spray boom was equipped with D-1245 nozzles calibrated to deliver 2 gal water per acre at 28 psi at 120 mph. Test 1 treatments were applied 24 Jul. Test 2 treatments were applied 1 Aug. Efficacy was determined by comparing the no. of plants infested with WBC larvae before treatment to the no. of infested plants after treatment (larvae in the ear tips).

Trophic Dynamics of a Nebraska Black Crappie and White Crappie Population

Abstract Diet variations of black crappie (Pomoxis nigromaculatus) and white crappie (Pomoxis annularis) were investigated at Hayes Center State Lake, a turbid 20-hectare state lake in southwest Nebraska. Zooplankton and insects accounted for most of the diet of all black crappie and of white crappie less than 200 mm long. The daily ration of planktophagic crappie declined to 1.3% as both species approached a length of 200 mm. Black crappie longer than 200 mm did not convert to fish and the daily ration declined to 0.8%. The dietary shift of white crappie to fish significantly increased the average volume of food as the daily ration increased to 1.6 and 2.9% at 200-249 and ≳ 250 mm, respectively. Crappie growth and survivorship were affected by the nature of the food. White crappie were 2.4 times more numerous and grew faster with improved survival at Age IV compared to the less dense black crappie population. Mortality rates of black crappie related positively to their size and water temperature during t...

The Direct Measurement of the Sizes, Shapes and Kinematics of Falling Hailstones

The kinematic behavior of hailstones falling in their natural environment near the surface was studied using stroboscopic photography in a mobile van. The experimental results permitted determination of the shape and dimensions, velocity, and in a few cases the rotation rate, of hailstones failing into the van. Hailstones were sampled in southeast Wyoming, southwest Nebraska and northeast Colorado. About 84% of the hailstones photographed were classified spheroidal, the remainder being roughly conical. Change in orientation of stones is observed in most photographs, though only ∼6% of the hailstones could be assigned a rotation rate. Velocity data were obtained for more than 600 hailstones in the diameter range 5-25 mm. It is shown that the vertical velocity component of hailstones near the surface (air density =9.93×10−4 g cm−3) can be predicted by the expression VT where De0.50 (±m s−1), Deis the equivalent volume diameter of a spherical hailstone in centimeters. Fall-speed and hailstone oblateness are shown to be slightly negatively correlated. Hailstone drag co-efficients, as inferred from the measured vertical velocities, are found to be higher than the values most frequently quoted in the literature. A mean drag coefficient of 0.87 is found over a range of Reynolds numbers from 1032×104 with a tendency for the drag coefficient to decrease with increasing Reynolds number. Implications of the fallspeed and drag coefficient results on hailstone growth and hail instrument calibration are discussed. The time dependence of hailstone size is presented for two storms. A comparison of hailstone size versus arrival time indicates, at least for one of the storms, that the stones may have been size sorted.

Fall and Winter Habits of Prairie Chickens in Southwest Nebraska

Fall and Winter Habits of Prairie Chickens in Southwest Nebraska