Lower Mississippi River Valley Research Articles

Historical and contemporary drivers of knickpoint retreat and morphological evolution along Bayou Pierre, Mississippi

AbstractChannel incision in rivers can cause marked ecological and economic damages. This phenomenon is abundant and generally well documented along impacted streams in the loess hills adjacent to the Lower Mississippi River valley. Bayou Pierre, an ecologically important small tributary of the Mississippi River, is currently incising but causes are not well understood. In this study, we examine diverse data sources to: (1) reconstruct a history of erosional stimuli and possible origins and (2) examine effects of contemporary controls. Review of long‐term planform and land use data for the Mississippi River revealed episodic foreshortening events followed by episodic deforestation and reforestation. Hydrologic data suggest an increase in rainfall over the last few decades. Estimates of knickpoint retreat place origins prior to Mississippi River channel straightening (1929–1944). Planform analysis in three focal reaches of Bayou Pierre demonstrates slow change prior to 1982, but accelerated changes after those periods. Mean rainfall and 3‐day storm intensity correlate to some planform changes; however, the storm of 1983 may be a better explanation of sudden planform change. We found some evidence of potential internal feedback loops in patterns of bar growth. Together, our analyses provide a synthesis of stimuli experienced by Bayou Pierre over the last ~200 years and suggest both channel migration events before straightening of the Mississippi River and more recent hydrologic events have influenced patterns of geomorphic change in Bayou Pierre.

The Southern Picturesque: Visions of the New and Old South in the Lower Mississippi River Valley

Abstract This essay examines the southern picturesque, an architectural vision of the Old South formulated in the 1910s through 1930s in the Lower Mississippi River valley. This vision offered an oblique approach to the plantation big house that evoked a mythical antebellum past, presenting this fulcrum of chattel slavery and resource extraction as an image of leisurely natural order where climate assumed primary importance in the shaping of architectural form. Drawings and texts composed by architect and Tulane University professor Nathaniel Curtis, architect-artist William Spratling, and writer Natalie Scott participated in this maudlin display of the Old South. As this article argues, their work represented a kind of partially uprooted modernism that was in fact made possible by the expansion of the oil industry into the very same environment celebrated by the southern picturesque for its agrarian, nonindustrial authenticity.

Cover crop effects on infiltration, aggregate stability, and water retention in the Lower Mississippi River Valley

AbstractCover crops are widely considered to improve soil health in the form of erosion control, organic matter additions, and improving water‐holding capacity. Despite the generally well‐documented benefits, cover crops remain under‐studied in the Lower Mississippi River Valley (LMRV), an area historically dominated by intensive cultivated agriculture, with soils prone to erosion, and where the need for irrigation has led to unsustainable aquifer withdrawals. The objective of this study was to evaluate cover crop (with cover crops [CC] and without cover crops [NCC]) effects on near‐surface soil physical, chemical, and hydraulic properties. Soil sample collection and in situ measurements were conducted, once per site, between May 2018 and May 2019 across four locations within the LMRV portion of eastern Arkansas. Overall and steady‐state infiltration rates were unaffected (p > .05) by cover‐crop treatment. Across all locations, extractable soil Na content in the top 10 cm was greater (p ≤ .05) with NCC (31.6 kg ha−1) compared with CC (21.6 kg ha−1). Averaged across treatment and soil depth (0 to 5 and 5 to 10 cm), water‐stable aggregate concentration in the 0.25‐ to 0.5‐ (0.101 g g−1) was 1.5 times greater (p ≤ .05) than that in the 1.0‐ to 2.0‐mm size class (0.068 g g−1). Though many soil properties did not significantly differ between CC treatments due to their collective variations, results of this study demonstrate the wide‐spread implications of CC use on physical, chemical, and hydraulic properties across a region.

Elizabeth L. Jemison. Christian Citizens: Reading the Bible in Black and White in the Postemancipation South.

Scholars have long recognized that citizenship was perhaps the most hotly contested concept in America in the second half of the nineteenth century. From Dred Scott v. Sandford to the Fourteenth Amendment to Plessy v. Ferguson, both the meaning of citizenship and its relationship to equality were unstable. As Elizabeth L. Jemison argues in Christian Citizens: Reading the Bible in Black and White in the Postemancipation South, Christianity’s role in shaping the meaning of citizenship in postemancipation America has not been fully appreciated. Jemison’s main contention is that Christian identity was central to emerging conceptions of citizenship and thus is indispensable for understanding both African Americans’ aspirations for equality and white southerners’ attempts to maintain a racial hierarchy through violence and segregation. Jemison builds on the taxonomy of three competing religious visions for the postemancipation South—of Black southerners, of white southerners, and of white northern missionaries—that Daniel W. Stowell established in Rebuilding Zion: The Religious Reconstruction of the South, 1863–1877. The first vision maintained that African Americans’ status as Christians meant they should be equal citizens. In contrast, white southern Christians adapted the paternalistic rhetoric of proslavery theology to defend a racially exclusivist understanding of citizenship. Lastly, white northern missionaries advanced their own form of paternalism that separated Black Christian identity from Black civil and political rights. Jemison’s book, which examines the lower Mississippi River valley of Arkansas, Louisiana, Mississippi, and western Tennessee, mostly confirms Stowell’s earlier work on Georgia and eastern Tennessee.

The Shattered Cross: French Catholic Missionaries on the Mississippi River, 1698-1725 by Linda Carol Jones

Reviewed by: The Shattered Cross: French Catholic Missionaries on the Mississippi River, 1698-1725 by Linda Carol Jones Kenneth C. Carstens Linda Carol Jones. The Shattered Cross: French Catholic Missionaries on the Mississippi River, 1698-1725. Baton Rouge: LSU Press, 2020. Pp. 297. Figures. Index. Maps. Notes. Cloth: $50.00. I have been fascinated by early (colonial) New World Catholic missionaries since 1959, when my parents first took me to Fort Michilimackinac at the tip of Michigan's Lower Peninsula, then farther north to St. Ignace and Sault Ste. Marie, both in the Upper Peninsula. There, I learned firsthand about the work of the early Jesuit fathers, and their attempts (some successful, some not) to bring Native Americans to Christianity. By the mid-1960s, I had read Vernon Kinietz's book Indian Life in the Upper Great Lakes, 1615-1760 (1965), which further fostered my interest about the assimilation and acculturation process behind culture change. As a budding anthropologist, I read Reuben Thwaites's seventy-three-volume work Jesuit Relations and Allied Documents, 1610-1791 (1853-1915) through my college years at Central Michigan University. Now, added to these noted works, is a new book written by Linda Carol Jones. Jones, an associate professor of language area studies at the University of Arkansas, has further documented the influence of Jesuits from the Great Lakes area into the middle and lower Mississippi River valley. After reading Jones's work, I am confident her book will be considered of equal importance to the writings of Kinietz and Thwaites whenever studies about early colonial Jesuit history of the pays d'en haut are mentioned. Jones details the extraordinary, often reciprocal, and dynamic interactions (both good and bad) among different Native and European groups along the Mississippi River during the colonial (contact period) era. These dynamic cultural interactions might be Natives (various Illini groups and groups located further south along the Mississippi, like the Tamarois, Quapaw, Chickasaw, Natchez, or others) with other Natives; Natives and Europeans—the world of European traders (both French and English), coureurs de bois, and metis—and Europeans with other Europeans (e.g., Jesuits with various political leaders such as Cadillac, Iberville, or Bienville), explorers (e.g., LaSalle and Tonti), religious leaders (whether back in Montreal with the Petit Séminaire de Québec, in Paris, or with the Holy See at the Vatican), or different missionary sects also vying for Native converts to baptize. Indeed, Jones's book details the significant, and extremely complex, ideological and political considerations Jesuit fathers needed to "stay alive" (although martyrdom was not a bad thing if done for the right reasons), and how best to convert Natives to Christianity: force-feeding Christianity and European values to Native Americans in what Jones calls "Frenchification" (that is, forcefully [End Page 151] making Natives French men and women), or finding ways (linguistically or culturally) that Native Americans themselves selected to adopt; that is, letting the choice of acceptance or rejection be a Native one, whether for what the idea was, or a modification of the idea as it would best fit a Native cultural need or understanding. Indeed, when Frenchification was forced on Natives, the results ended in a "shattered cross." Although I considered my background in Jesuit history in North America better than average, I learned so much more about Colonial Jesuit history that I did not know previously, especially regarding the political climate between Jesuits and church leadership (that is, "Jesuits in the field" versus church leadership in Montreal, Paris, or the Vatican). Nor was I aware that the idea to begin missionary work among Native Americans along the Mississippi River had its origin in seventeenth-century Jesuit fathers in China. And although church philosophy in the late 1600s and early 1700s was to force "Frenchification" on the Natives, Jesuits who were the most successful as Christian missionaries were those who practiced love, allowing Natives to accept or reject on their own terms what part of French culture and Catholicism best served their needs. Colonialism, including intentional forms of assimilation, acculturation, and—yes—genocide, is not to be condoned in today's world. But it did happen. Ignoring that it happened presents an incomplete...

Landuse and soil property effects on infiltration into Alfisols in the Lower Mississippi River Valley, USA

Unsustainable, agriculturally related practices of water usage have caused increasing groundwater depletion in the Alluvial Aquifer in the Lower Mississippi River Valley (LMRV) of eastern Arkansas. To avoid further depletion, one method of decreasing drawdown of the Alluvial Aquifer would be to adopt agricultural management practices that increase surface infiltration, which would increase the amount of water that could potentially recharge the aquifer. The objective of this study was to evaluate surface water infiltration and infiltration-related properties in fine-textured, loessial and alluvial Alfisols under different land managements in the LMRV Delta region of eastern Arkansas. Falling-head, double-ring infiltration measurements (n = 105) were conducted as a completely random experimental design between November 2015 and July 2016 in six current major landuses: native prairie, deciduous forest, coniferous forest, Conservation Reserve Program (CRP) grassland, conventional-tillage (CT) agriculture, and no-tillage (NT) agriculture. The overall infiltration rate for the 20-min measurement interval for the deciduous forest (1.17 mm min−1) was 6.7 times greater (P < .05) than that for the other five landuses, which did not differ and averaged 0.17 mm min−1. Overall infiltration rate was positively correlated (P < .05) with soil organic matter (SOM), total C, and total N contents and C:SOM ratio, while negatively correlated (P < .05) with estimated bulk density and extractable soil Na and Mg contents in the top 10 cm. Restoration of highly erodible agricultural lands in the LMRV should consider reforestation activities with deciduous species to contribute to improved infiltration capacity that can contribute to potentially greater groundwater recharge.

Soil Aggregate Stability as Affected by Landuse and Soil Properties in the Lower Mississippi River Valley

Core Ideas Improving soil aggregation may promote infiltration. Soil aggregation properties differ by land use. Grassland and forest restoration may improve groundwater recharge. Improving soil aggregate stability, thus improving infiltration and reducing surface runoff and soil erosion, may lead to multiple environmental benefits in the Lower Mississippi River Valley (LMRV). The objective of this study was to evaluate the effects of common landuses (i.e., native prairie, deciduous forest, coniferous forest, Conservation Reserve Program [CRP] grassland, and conventional‐tillage [CT] and no‐tillage [NT] agriculture), aggregate‐size class, and soil depth on aggregate‐stability‐related properties on fine‐textured, loessial and alluvial soils in the Arkansas Delta region of the LMRV. Total water‐stable aggregate (TWSA) concentrations in the top 10 cm in the native prairie, CRP, and coniferous forest were similar (p &gt; 0.05) to each other, averaging 806 g kg−1, and were 35% greater (p &lt; 0.05) than that of the NT and CT agroecosystems, which did not differ and averaged 605 g kg−1. The mean weight diameter (MWD) in the top 10 cm in the native prairie, CRP, and coniferous forest was similar (p &gt; 0.05) to each other, averaging 2.1 mm, and were 70% greater (p &lt; 0.05) than that in the NT and CT agroecosystems, which did not differ and averaged 1.3 mm. In the top 5 cm, the MWD and TWSA concentration were 17 and 8% greater (p &lt; 0.05), respectively, than that in the 5‐ to 10‐cm depth interval. Grassland and forest restoration, specifically of highly erodible agricultural land, should be considered to contribute to improvements in soil structural stability and the future sustainability of soil and water resources in the LMRV.

Using Rainfall Analysis to Manage Freeboard and Increase Rainfall Capture for Multiple-Inlet Rice Irrigation in the Lower Mississippi River Valley

AbstractResearch was conducted to help rice (Oryza sativa L.) farmers increase rainfall capture to offset groundwater use in the Lower Mississippi River Valley (LMRV). The LMRV is where a majority ...

Infiltration as affected by long-term residue and water management on a loess-derived soil in eastern Arkansas, USA

Improving the understanding of alternative and conventional management practices and their interactions on soil hydraulic properties is instrumental to soil, groundwater, and irrigation water management in the Lower Mississippi River Valley (LMRV), particularly the Delta region of eastern Arkansas. For decades, extensive regional groundwater withdrawals for irrigated agriculture has caused severe groundwater depletion. The objective of this field study was to evaluate the effects of alternative and conventional management practices, including wheat-residue level, residue burning, tillage, and irrigation, on falling-head and tension infiltration into a silt-loam-textured loessial soil (Glossaquic Fraglossudalf) following 11 and 14 years of consistent management in a long-term, wheat (Triticum aestivum L.)-soybean (Glycine max [L.] Merr.), double-crop (WSDC) production system in eastern Arkansas. In 2012, averaged across tillage, residue-level, and irrigation treatments, the overall tension infiltration rate at a tension of −2 cm into the no-burn (16.1 cm h−1) was over 300% greater (P < .01) than that into the burn treatment (5.3 cm h−1). In 2015, averaged across residue-level and irrigation, falling-head infiltration was 278% greater (P = .05) from the no-tillage (NT)-no-burn (4.35 cm h−1) than the conventional tillage (CT)-burn treatment combination (1.15 cm h−1), while the NT-burn (1.85 cm h−1) and CT-no-burn combinations (1.85 cm h−1) did not differ and were intermediate. Greater understanding of the effects of alternative agronomic management practices in a WSDC system on infiltration and surface hydraulic properties can lead to direct and indirect improvements in soil health, aquifer recharge, crop productivity, and overall resource sustainability in the LMRV.

Rapid climate change-induced collapse of hunter-gatherer societies in the lower Mississippi River valley between ca. 3300 and 2780 cal yr BP

Hunter-gatherer communities in the American Southeast reached an apogee of social and political complexity in the period between ca. 4200 and 3000 cal yr BP. In the lower Mississippi Valley (LMV) the Poverty Point culture defined this period of socio-political elaboration. However, following a significant period of climate change that led to exceptional flooding and a major reorganization of the course of the Mississippi River, this culture collapsed beginning ca. 3300–3200 cal yr BP and the LMV was abandoned for the subsequent 500 years. In this study, we use data from the Jaketown site in the Yazoo Basin of west-central Mississippi to refine the chronology of the climate event that caused the collapse of the Poverty Point culture. A large flood buried Poverty Point-era occupation deposits at Jaketown around 3310 cal yr BP. Lateral migration of the Mississippi River during flooding led to inundation of the Yazoo Basin and re-occupation of ancient river courses. A coarse sand stratum topped by a more than a meter-thick fining upward sediment package marks a crevasse deposit caused by a rupture of the natural levee at Jaketown. This levee breach was part of a larger pattern of erratic flooding throughout the LMV and is associated with major landscape evolution and the abandonment of Poverty Point sites within the valley. Early Woodland peoples re-colonized the crevasse surface after ca. 2780 cal yr BP. Following this event, the Jaketown site and the eastern Yazoo Basin witnessed a period of landscape stability that lasts to this day. These archaeological data demonstrate how climate change and natural disasters can lead to socio-political dissolution and reorganization even in relatively small-scale hunter-gatherer populations.

Accuracy Analysis Comparison of Supervised Classification Methods for Anomaly Detection on Levees Using SAR Imagery

This paper analyzes the use of a synthetic aperture radar (SAR) imagery to support levee condition assessment by detecting potential slide areas in an efficient and cost-effective manner. Levees are prone to a failure in the form of internal erosion within the earthen structure and landslides (also called slough or slump slides). If not repaired, slough slides may lead to levee failures. In this paper, we compare the accuracy of the supervised classification methods minimum distance (MD) using Euclidean and Mahalanobis distance, support vector machine (SVM), and maximum likelihood (ML), using SAR technology to detect slough slides on earthen levees. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory’s (JPL’s) uninhabited aerial vehicle synthetic aperture radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers.

The acoustics and sound environments of Early Delta Blues

As part of a larger investigation into the archaeological origins of the blues, I seek to re-create the sound environments that surrounded and informed the initial emanations of this important American music genre. This study is warranted because the music has had such a pronounced influence on global musics, as well as on broader sociological concerns like race, regionalism, nationalism, capitalism, and gender. It is also of value for archaeo-acoustic studies in that it concerns a study of an archaeo-historic site that is not in the deep past. For the ASA meeting-forum I will report on two related acoustic processes: one is the digital reconstruction of the physical structures where the blues was first heard, such as wood-framed shotgun-shaped performance spaces (juke joints, general stores), some of which still exist in the Mississippi Delta (Po Monkeys near Merigold and Mary’s in Indianola), or can be archaeologically recovered (the general store at Dockery Farms); and the second process is a recreation of the sonic environment of the late 19th early 20th century south of the lower Mississippi river valley, including natural and anthropomorphic sounds. These steps precede a future goal, the archaeologically reconstructed instrumental and vocal sounds of incipient and early blues, allowing for a truer picture of this musical phenomenon than currently exists.

Impacts of Local Soil Moisture Anomalies on the Atmospheric Circulation and on Remote Surface Meteorological Fields during Boreal Summer: A Comprehensive Analysis over North America

Abstract A series of stationary wave model (SWM) experiments are performed in which the boreal summer atmosphere is forced, over a number of locations in the continental United States, with an idealized diabatic heating anomaly that mimics the atmospheric heating associated with a dry land surface. For localized heating within a large portion of the continental interior, regardless of the specific location of this heating, the spatial pattern of the forced atmospheric circulation anomaly (in terms of 250-hPa eddy streamfunction) is largely the same: a high anomaly forms over west-central North America and a low anomaly forms to the east. In supplemental atmospheric general circulation model (AGCM) experiments, similar results are found; imposing soil moisture dryness in the AGCM in different locations within the U.S. interior tends to produce the aforementioned pattern, along with an associated near-surface warming and precipitation deficit in the center of the continent. The SWM-based and AGCM-based patterns generally agree with composites generated using reanalysis and precipitation gauge data. The AGCM experiments also suggest that dry anomalies imposed in the lower Mississippi River valley have remote surface impacts of particularly large spatial extent, and a region along the eastern half of the U.S.–Canadian border is particularly sensitive to dry anomalies in a number of remote areas. Overall, the SWM and AGCM experiments support the idea of a positive feedback loop operating over the continent: dry surface conditions in many interior locations lead to changes in atmospheric circulation that act to enhance further the overall dryness of the continental interior.

A Supervised Classification Method for Levee Slide Detection Using Complex Synthetic Aperture Radar Imagery

The dynamics of surface and sub-surface water events can lead to slope instability, resulting in anomalies such as slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We have implemented a supervised Mahalanobis distance classification algorithm for the detection of slough slides on levees using complex polarimetric Synthetic Aperture Radar (polSAR) data. The classifier output was followed by a spatial majority filter post-processing step that improved the accuracy. The effectiveness of the algorithm is demonstrated using fully quad-polarimetric L-band Synthetic Aperture Radar (SAR) imagery from the NASA Jet Propulsion Laboratory’s (JPL’s) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the southern USA. Slide detection accuracy of up to 98 percent was achieved, although the number of available slides examples was small.

Advanced Unsupervised Classification Methods to Detect Anomalies on Earthen Levees Using Polarimetric SAR Imagery.

Fully polarimetric Synthetic Aperture Radar (polSAR) data analysis has wide applications for terrain and ground cover classification. The dynamics of surface and subsurface water events can lead to slope instability resulting in slough slides on earthen levees. Early detection of these anomalies by a remote sensing approach could save time versus direct assessment. We used L-band Synthetic Aperture Radar (SAR) to screen levees for anomalies. SAR technology, due to its high spatial resolution and soil penetration capability, is a good choice for identifying problematic areas on earthen levees. Using the parameters entropy (H), anisotropy (A), alpha (α), and eigenvalues (λ, λ1, λ2, and λ3), we implemented several unsupervised classification algorithms for the identification of anomalies on the levee. The classification techniques applied are H/α, H/A, A/α, Wishart H/α, Wishart H/A/α, and H/α/λ classification algorithms. In this work, the effectiveness of the algorithms was demonstrated using quad-polarimetric L-band SAR imagery from the NASA Jet Propulsion Laboratory’s (JPL’s) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area is a section of the lower Mississippi River valley in the Southern USA, where earthen flood control levees are maintained by the US Army Corps of Engineers.

Factors affecting methane emissions from rice production in the Lower Mississippi river valley, USA

Rice (Oryza sativa L.) plays a key role in sustaining global food security; however, rice production also accounts for a significant proportion of global methane (CH4) emissions, a major greenhouse gas involved in altering global climate. Many previous studies have quantified the proportion of CH4 emissions by independently evaluating factors such as soil texture and cultivars – an approach that has led to potentially biased estimates of their actual contribution to total emissions. Most of these studies have not considered the influence of the preceding crop or growing-season weather that could lead to a significant variation in carbon budgets. The main objective of this study was to identify the key edaphic, cultivar, and environmental factors and determine their proportional contributions towards CH4 emissions in direct-seeded, rice-based cropping systems. A multiple regression model was developed to quantify CH4 emissions as a function of temperature (both day and night independently and in combination) and other weather variables, soil (silt-loam-surface-textured Albaqualf and clay-surface-textured Epiaquert), cultivar (conventional and hybrid), and cropping system (rice-rice and soybean [Glycine max L.]-rice). Results showed that (i) the Albaqualf emitted 211% more CH4-C than the Epiaquert (P<0.01; (ii) inbred cultivars accounted for 55 to 70% more CH4-C emissions than hybrid cultivars (P<0.01); (iii) soybean-rice rotations produced 58% less CH4-C emissions than rice-rice rotations (P<0.01); and (iv) future warming scenarios increased CH4-C emissions by up to 53%. To mitigate CH4 emissions, future research and crop production strategies that prioritize rice production on clay-surface-textured soils and use alternatives to a rice-rice rotation are recommended.

Investigating the Function of an Archaic-Period Earthwork Using Microartifacts

The functions of Archaic-period mounds in the Lower Mississippi River valley are generally poorly understood. Poverty Point's Mound C provides a unique opportunity to examine the function of one Late Archaic mound. Archaeological excavation of Mound C revealed a complex construction sequence consisting of numerous, thin, flat-topped construction stages. The presence of cultural features on the surfaces of some stages suggests these mound stage summits were used for cultural activities. The nearly complete absence of macroartifacts, however, makes it difficult to discern the types of activities undertaken on these surfaces. Microartifacts from the surfaces of these construction platforms provide an alternative perspective on the nature of activities associated with this earthwork. The analysis of microartifacts from Mound C, coupled with the limited number of macroartifacts, suggests that individual mound stage summits were intentionally cleaned prior to the addition of subsequent construction stages. The Mound C microartifact assemblages further indicate that this architectural feature was used unlike any other previously excavated context at Poverty Point.

Double Impact: When Both Tornadoes and Flash Floods Threaten the Same Place at the Same Time

Abstract While both tornadoes and flash floods individually present public hazards, when the two threats are both concurrent and collocated (referred to here as TORFF events), unique concerns arise. This study aims to evaluate the climatological and meteorological characteristics associated with TORFF events over the continental United States. Two separate datasets, one based on overlapping tornado and flash flood warnings and the other based on observations, were used to arrive at estimations of the instances when a TORFF event was deemed imminent and verified to have occurred, respectively. These datasets were then used to discern the geographical and meteorological characteristics of recent TORFF events. During 2008–14, TORFF events were found to be publicly communicated via overlapping warnings an average of 400 times per year, with a maximum frequency occurring in the lower Mississippi River valley. Additionally, 68 verified TORFF events between 2008 and 2013 were identified and subsequently classified based on synoptic characteristics and radar observations. In general, synoptic conditions associated with TORFF events were found to exhibit similar characteristics of typical tornadic environments, but the TORFF environment tended to be moister and have stronger synoptic-scale forcing for ascent. These results indicate that TORFF events occur with appreciable frequency and in complex meteorological scenarios. Furthermore, despite these identified differences, TORFF scenarios are not easily distinguishable from tornadic events that fail to produce collocated flash flooding, and present difficult challenges both from the perspective of forecasting and public communication.

Modeling the Present and Future Geographic Distribution of the Lone Star Tick, Amblyomma americanum (Ixodida: Ixodidae), in the Continental United States.

The Lone star tick (Amblyomma americanum L.) is the primary vector for pathogens of significant public health importance in North America, yet relatively little is known about its current and potential future distribution. Building on a published summary of tick collection records, we used an ensemble modeling approach to predict the present-day and future distribution of climatically suitable habitat for establishment of the Lone star tick within the continental United States. Of the nine climatic predictor variables included in our five present-day models, average vapor pressure in July was by far the most important determinant of suitable habitat. The present-day ensemble model predicted an essentially contiguous distribution of suitable habitat extending to the Atlantic coast east of the 100th western meridian and south of the 40th northern parallel, but excluding a high elevation region associated with the Appalachian Mountains. Future ensemble predictions for 2061-2080 forecasted a stable western range limit, northward expansion of suitable habitat into the Upper Midwest and western Pennsylvania, and range contraction along portions of the Gulf coast and the lower Mississippi river valley. These findings are informative for raising awareness of A. americanum-transmitted pathogens in areas where the Lone Star tick has recently or may become established.

Carbon dioxide emissions as affected by alternative long-term irrigation and tillage management practices in the lower Mississippi River Valley.

Ensuring the sustainability of cultivated soils is an ever-increasing priority for producers in the Lower Mississippi River Valley (LMRV). As groundwater sources become depleted and environmental regulations become more strict, producers will look to alternative management practices that will ensure the sustainability and cost-effectiveness of their production systems. This study was conducted to assess the long-term (>7 years) effects of irrigation (i.e., irrigated and dryland production) and tillage (conventional and no-tillage) on estimated carbon dioxide (CO2) emissions from soil respiration during two soybean (Glycine max L.) growing seasons from a wheat- (Triticum aestivum L.-) soybean, double-cropped production system in the LMRV region of eastern Arkansas. Soil surface CO2 fluxes were measured approximately every two weeks during two soybean growing seasons. Estimated season-long CO2 emissions were unaffected by irrigation in 2011 (P > 0.05); however, during the unusually dry 2012 growing season, season-long CO2 emissions were 87.6% greater (P = 0.044) under irrigated (21.9 Mg CO2 ha−1) than under dryland management (11.7 Mg CO2 ha−1). Contrary to what was expected, there was no interactive effect of irrigation and tillage on estimated season-long CO2 emissions. Understanding how long-term agricultural management practices affect soil respiration can help improve policies for soil and environmental sustainability.