Northern Mississippi Research Articles

Using Repeated Lysis Steps Fractionates Between Heterotrophic and Cyanobacterial DNA Extracted from Xenic Cyanobacterial Cultures.

Extracting DNA from cyanobacteria can be a challenge because of their diverse morphologies, challenging cellular structure, and the heterotrophic microbiome often present within cyanobacterial cultures. As such, even when our DNA yields are sufficient for sequencing, the percentage of reads coming from the cyanobacterial host can be low, leading to incomplete genomes spread across several scaffolds. In this research, we optimized a DNA isolation protocol using three iterative cell lysis steps to enrich the portion of DNA isolated coming from the cyanobacterial host rather than the heterotrophic microbiome. In order to utilize in-house nanopore sequencing, we faced a challenge in that our lysis protocol led to DNA shearing and a lower molecular weight DNA extract than is suitable for this sequencing technology. As such we used two bead-based size selection steps to remove shorter molecules of DNA before nanopore sequencing. EPI2ME analysis of the processed reads from the iterative lysis steps showed that in the first lysis the heterotrophic microbiome could make up more than half of all reads, but with each lysis the proportion of reads coming from these other species decreased. Using our iterative lysis protocol, we were able to sequence the genomes of two cyanobacteria isolated from fresh water sources around northern Mississippi, namely Leptolyngbya sp. BL-A-14 and Limnothrix sp. BL-A-16. The genomes of these isolates were assembled as closed chromosomes of 7.2 and 4.5 Mb for Leptolyngbya sp. BL-A-14 and Limnothrix sp. BL-A-16, respectively. Because some cyanobacteria have symbioses with their heterotrophic microbiome it is not always possible to prepare axenic cultures of these organisms, we hope our approach will be useful for sequencing xenic cultures of cyanobacteria, but we can also imagine applications in studying this microbiome specifically by focusing sequencing efforts on the first fraction.

TGFs, Gamma‐Ray Glows, and Direct Lightning Strike Radiation Observed During a Single Flight of a Balloon‐Borne Gamma‐Ray Spectrometer

AbstractTerrestrial gamma‐ray flashes (TGFs) and other high‐energy radiation phenomena related to thunderstorms remain incompletely understood since their discovery nearly 30 years ago. Space and ground‐based platforms have provided insights, but limitations exist in temporal resolution, signal‐to‐noise ratios, and proximity to events. This study presents findings from a balloon‐borne gamma‐ray spectrometer flown into a thunderstorm over northern Mississippi on 19 June 2023. The instrument detected three distinct millisecond‐duration TGF events correlated with lightning strikes. Sustained gamma‐ray glows lasting up to 2 minutes were measured and tied to thunderstorm electrostatic fields. Notably, radiation was observed during a direct lightning strike to the payload. This complex 800‐millisecond event reveals insights into radiation from leader propagation and return strokes. These findings from a single balloon flight demonstrate the prevalence of energetic processes within thunderstorms. Finally, the balloon platform offered an exceptional combination of temporal resolution and validation capabilities to advance the understanding of thunderstorm radiation motivating future follow‐up studies.

Expanding CWD disease surveillance options using environmental contamination at deer signposts

Abstract Environmental surveillance can allow early detection of diseases, which increases management options and can improve disease trajectories. Chronic wasting disease (CWD) in cervids is a significant prion disease that has been spreading across North America since the 1960s, leading to cervid population declines and concern from hunters and state wildlife agencies. White‐tailed deer have a unique breeding season behaviour called scraping, where they deposit urine and saliva at shared sites. Since both these fluids can contain CWD prions, scrape sites have the potential to serve as sentinel sites for environmental surveillance of CWD. To examine this potential, we used camera traps to monitor deer behaviour and collected environmental samples from 105 scrape sites. The 48 km2 study site was located at the centre of the CWD zone in southwestern Tennessee, where CWD prevalence is ~50%. We also sampled scrapes in northern Mississippi at the leading edge of the same CWD distribution to test the potential for early CWD detection using scrape sampling. From camera data, we identified 218 unique bucks visiting 105 scrapes, with a mean of 12.2 ± 7.5 bucks per scrape (mean ± SD, range 1–39) and individual bucks visiting a mean of 5.9 ± 4.6 monitored scrapes each (range 1–23). Using real‐time quaking‐induced conversion (RT‐QuIC), we detected prion seeding activity in 20% of the soil and 41% of the licking branches of the scrape sites within the CWD study area, and in 25% of the soil and 11% of the licking branches of scrape sites sampled at the edge of the known CWD distribution. Our data show there is environmental prion contamination at scrape sites. This supports the idea that scrapes could serve as early warning sentinel sites for CWD surveillance through testing soil and licking branches for prion seeding activity, especially in areas with limited access to harvested deer samples.

Early silvicultural intervention affects species dominance in efforts to restore pine-hardwood mixedwoods following stand-replacing disturbance

Interest in replacing monocultures with species diverse stands has steadily grown. Mixedwoods (stands containing a balance of conifer and hardwood species) represent an alternative to monocultures and occur naturally through forest succession on most sites in eastern North America. In the central and southeastern United States, mixedwoods were generally dominated by pine and upland oak species. However, a combination of anthropogenic land use legacies has allowed fire-sensitive species to establish creating an opportunity for different mixedwood types to develop (e.g., pine-oak, pine-poplar, pine-gum). While any mixedwoods combination would increase tree species diversity relative to a monoculture, interest exists in whether silvicultural intervention can improve the performance of individual species to promote the development of different mixture types based on specific management objectives (e.g., wildlife habitat, timber quality, drought resistance). To address this question, we established an experiment examining the response of juvenile volunteer loblolly pine and six planted hardwood species (northern red oak, white oak, sweetgum, blackgum, yellow-poplar, and mockernut hickory to four silvicultural treatments (controlled release hardwood fertilization, coppicing, coppicing + broadcast fertilization, and planted control) in northern Mississippi, USA.Four-years post-planting, our results demonstrate that all treatments produced loblolly pine-hardwood co-dominance; however, hardwood dominance varied among treatments. In the planted control, loblolly pine and sweetgum were the co-dominant species, and statistically outgrew all species except yellow-poplar. Mockernut hickory (+ 40%), yellow-poplar (+ 23%), and blackgum (+ 15%) seedling height increased in controlled release fertilization compared to the planted control; however, apart from northern red oak, seedling survival of all hardwood species was less than 50%. The controlled release hardwood fertilization treatment was co-dominated by loblolly pine, yellow-poplar, and sweetgum. Sprouting in the coppiced treatment (89%) statistically exceeded that in the coppiced + broadcast fertilization treatment (73%), but did not vary among species. In general, coppicing reduced sprout height and survival relative to seedlings in the planted control, and promoted loblolly pine, yellow poplar, and sweetgum co-dominance. Coppicing + broadcast fertilization consistently reduced sprout survival compared to the planted control. However, trends in seedling height were mixed, with northern red oak (+ 14%) showing the largest improvement, and volunteer loblolly pine the largest decline (- 34%). Moreover, coppicing + broadcast fertilization produced the most species diverse outcome featuring yellow-poplar, loblolly pine, sweetgum, and northern red oak in co-dominant growing positions. Collectively, these results indicate that sweetgum and loblolly pine are likely to be prominent species in contemporary mixedwoods regardless of treatment. However, more species-diverse mixtures may be promoted by coppicing and broadcast fertilizing early in stand development.

Bark and crown morphology drive differences in rainwater distribution in an upland oak forest

Throughout the central and eastern US, the composition and structure of upland oak (Quercus) forests are changing. These changes are in part due to fire exclusion, whereby shade-tolerant, often fire-sensitive tree species are gaining a competitive edge over relatively shade-intolerant, fire-adapted oaks. This shift has been hypothesized to occur via a positive feedback termed mesophication, whereby encroaching tree species (‘mesophytes’) create dense, shaded understory conditions that limit oak regeneration and create cooler and wetter microclimates that decrease forest flammability. The change in canopy composition and structure may also impact hydrologic inputs by redistributing rainfall via throughfall and stemflow. To assess the extent of this redistribution by mesophytes compared to oaks and the net impact to forest floor moisture availability, we monitored throughfall, stemflow, and surface soil moisture at depths of 7.6 cm, 12.0 cm, and 20.0 cm near the bole, mid-crown, and crown edge monthly over a 14-month period. Measurements were made across seasons in both the midstory and overstory canopy strata, including oak (Q. alba, Q. falcata) and non-oak species that are increasing in relative abundance in midstory canopy strata in northern Mississippi (Carya tomentosa, Acer rubrum, Ulmus alata). Non-oak species in the midstory (A. rubrum, U. alata) had smoother bark that led to more than three-times larger stemflow generation and more than two-times larger throughfall generation per basal area compared to oak species. However, there was mixed response to soil moisture, with both non-oak (A. rubrum) and oak (Q. falcata) species having wetter than average volumetric water content compared to all other midstory species. Overstory C. tomentosa generated 2.7-times larger stemflow volume than Q. alba while Q. alba generated the largest throughfall volume. Although overstory A. rubrum generated intermediate volumes of throughfall and stemflow, the cumulative effect led to wetter than average soils compared to all other overstory species. These findings suggest that the hydrologic partitioning by mesophyte crowns may serve as an additional mechanism by which encroaching non-oak species act to reduce forest flammability and promote conditions favorable for their own regeneration. This differential rainwater redistribution mechanism may ultimately compromise long-term oak regeneration and our ability to restore fire to fire-dependent forest ecosystems.

Seismic and Liquefaction Hazard Maps for Five Western Tennessee Counties

Abstract A five-year seismic and liquefaction hazard mapping project for five western Tennessee counties began in 2017 and supported natural hazard mitigation efforts in Lake, Dyer, Lauderdale, Tipton, and Madison counties. Additional geological, geotechnical, and geophysical information has been gathered in all five counties to improve the base northern Mississippi Embayment hazard maps of Dhar and Cramer (2017). Information gathered includes additional geological and geotechnical subsurface exploration logs, water table level data collection, new measurements of shallow shear-wave velocity (VS) profiles, and the compilation of existing VS profiles in and around the counties. Improvements have been made in the 3D geological model, water table model, the geotechnical liquefaction probability curves, and the VS correlation with lithology model for these counties. The resulting updated soil response amplification distributions on a 0.5 km grid were combined with the 2014 U.S. Geological Survey seismic hazard model (Petersen et al., 2014) earthquake sources and attenuation models to add the effect of local geology for Lake, Dyer, Lauderdale, Tipton, and Madison Counties. The resulting products are similar to the Memphis and Shelby County urban seismic hazard maps recently updated by Cramer, Dhar, and Arellano (2018). Generally, the effect of local geology is to reduce seismic hazard at short periods and increase it at long periods. Liquefaction hazard is high only in the alluvial lowlands, but not in the loess covered uplands.

Flora of six Lower Mississippi River islands (U.S.A.)

Lower Mississippi River islands are part of the last remaining floodplain habitat of the river, and studying their biodiversity is important to understand the river ecosystem. We conducted a floristic survey of six Lower Mississippi River islands between river miles 668 and 526 in southern Arkansas and northern Mississippi. These islands contain a variety of habitats and span a range of sizes, from 106 to 697 vegetated hectares. We identified 491 taxa (485 species plus six infraspecific taxa) from 2,310 specimens collected from June 2020 to December 2021. These taxa are within 89 families and 282 genera, and 100 (20.6%) species are not native to the Mississippi River drainage basin. Nine taxa found on Arkansas islands are tracked by the Arkansas Natural Heritage Commission for conservation. Five taxa found in Mississippi are tracked by the Mississippi Natural Heritage Program. We found five taxa that had not previously been reported in Arkansas (Equisetum variegatum, Achyranthes japonica var. hachijoensis, Stellaria aquatica, Potentilla paradoxa, Cyperus diandrus) and seven previously unreported in Mississippi (Euploca convolvulacea, Sisymbrium loeselii, Chaiturus marrubiastrum, Mentha canadensis, Potentilla norvegica, P. paradoxa, Physalis mollis). Additionally, we collected 266 Arkansas county records, including 132 in Phillips, 64 in Desha, and 28 in Chicot counties, respectively, and 42 in Washington County, Mississippi. The high number of new encounters and tracked species found emphasizes the need for more botanical study on Lower Mississippi River islands. Of the 485 species in the flora, we found 110 species on all six islands (22.7%), 43 on five of the six islands, 47 on four islands, 75 on three islands, 72 on two islands, and 138 on only one island (28.5%). The number of unique species found on only one island illustrates how variable and dynamic these islands are in this riparian zone.

Regional response of zoysiagrass turf to glufosinate and glyphosate applied during postdormancy transition based on accumulated heat units

AbstractTurfgrass managers apply nonselective herbicides to control winter annual weeds during dormancy of warm-season turfgrass. Zoysiagrass subcanopies, however, retain green leaves and stems during winter dormancy, especially in warmer climates. The partially green zoysiagrass often deters the use of nonselective herbicides due to variable injury concerns in transition and southern climatic zones. This study evaluated zoysiagrass response to glyphosate and glufosinate applied at four different growing degree day (GDD)-based application timings during postdormancy transition in different locations, including Blacksburg, VA; Starkville, MS; and Virginia Beach, VA, in 2018 and 2019. GDD was calculated using a 5 C base temperature with accumulation beginning January 1 each year, and targeted application timings were 125, 200, 275, and 350 GDD5C. Zoysiagrass injury response to glyphosate and glufosinate was consistent across a broad growing region from northern Mississippi to coastal Virginia, but it varied by application timing. Glyphosate application at 125 and 200 GDD5C can be used safely for weed control during the postdormancy period of zoysiagrass, while glufosinate caused unacceptable turf injury regardless of application timing. Glyphosate and glufosinate exhibited a stepwise increase to maximum injury with increasing targeted GDD5C application timings. Glyphosate applied at 125 or 200 GDD5C did not injure zoysiagrass above a threshold of 30%, whereas glufosinate caused greater than 30% injury for 28 and 29 d when applied at 125 and 200 GDD5C, respectively. Likewise, glyphosate application at 125 or 200 GDD5C did not affect the zoysiagrass green cover area under the progress curve per day, whereas later applications reduced it. Glyphosate and glufosinate caused greater injury to zoysiagrass when applied at greater cumulative heat units and this was attributed to increasing turfgrass green leaf density, because heat unit accumulation is positively correlated with green leaf density. Accumulated heat unit-based application timing will allow practitioners to apply nonselective herbicides with reduced injury concerns.

Implementing Service-Focused Activities Focused on Water Quality While Teaching a Freshmen Undergraduate Course During the COVID-19 Pandemic

Historically, high levels of self-reported stress, anxiety, and depression are quite common among STEM students. Unfortunately, after multiple semesters of disrupted education due to COVID-19, these mental struggles among students, especially first-year (freshmen) undergraduate engineering students, have only been exacerbated. To mitigate these struggles, active and thoughtful engagement in learning can be implemented. The main goal of this study was to implement an engaging, teamwork building, service-focused Environmental Engineering activity in a freshmen Civil Engineering course (CE 101, Introduction to Civil Engineering) where students performed a water quality monitoring campaign using two commercially available low-cost test strips (2:1 and 5:1) while returning to campus. Additionally, the quality of the results obtained and the students’ reception of this service-focused activity were evaluated. This activity (1) engaged the students, (2) had a positive impact on their environmental engineering knowledge, and (3) generated useful water quality data related to tap water and surficial water in northern Mississippi. Results highlighted the (1) overall good quality of the tap water collected, with the analyzed analytes significantly below the U.S. EPA maximum contaminant levels, (2) ability of low-cost test strips to generate trustworthy data (results obtained by the students were not statistically different, p > 0.05, compared to the quality assurance and quality control samples implemented) that can help local communities in assessing the quality of their water, and (3) ability to perform service-focused activity while teaching STEM courses. Students positively valued this service-focused activity, and they were enthusiastic about further experiencing this approach in other classes.

Life History Traits of Exotic and Native Species Determine Grassland Management Outcomes Following Prescribed Fire

<h3>ABSTRACT</h3> Disturbance regimes, including the historical timing of disturbance, are important components of natural ecosystems and greatly influence ecosystem structure and functioning. Consequently, disturbance timing can be an important component of biodiversity management. We evaluated the effect of prescribed fires ignited during the warm and cool seasons (summer and spring, respectively) on the plant community of a calcareous grassland in northern Mississippi (USA). We found that fire season influenced plant community composition by having differential impacts on species with different life history traits. Differences among species were primarily driven by the dichotomy between cool-season (C₃) and warm-season (C₄) plants, independent of species native status. Spring burns reduced the cover of cool-season C₃ graminoids, but had the opposite effect on C₄ graminoids, which likely benefited from increases in resource availability due to the reduction of C₃ species. However, summer burns decreased the abundance of C₄ graminoids, as summer burns were ignited during the active growing and reproductive period for the C₄ species. We found the same patterns for the number of inflorescences of the most abundant C₃ and C₄ graminoids. Summer burns also increased overall species diversity and the abundance of native C₃ graminoids, forbs, and vines, resulting in significant differences in plant community composition between spring- and summer-burned areas. Programs that aim to restore native grassland communities in the short-term using prescribed fire should consider the life history traits of target plants (including invasive species) to determine the best time for prescribed fire implementation.

Interconnected hydrologic extreme drivers and impacts depicted by remote sensing data assimilation

Hydrologic extremes often involve a complex interplay of several processes. For example, flood events can have a cascade of impacts, such as saturated soils and suppressed vegetation growth. Accurate representation of such interconnected processes while accounting for associated triggering factors and subsequent impacts of flood events is difficult to achieve with conceptual hydrological models alone. In this study, we use the 2019 flood in the Northern Mississippi and Missouri Basins, which caused a series of hydrologic disturbances, as an example of such a flood event. This event began with above-average precipitation combined with anomalously high snowmelt in spring 2019. This series of anomalies resulted in above normal soil moisture that prevented crops from being planted over much of the corn belt region. In the present study, we demonstrate that incorporating remote sensing information within a hydrologic modeling system adds substantial value in representing the processes that lead to the 2019 flood event and the resulting agricultural disturbances. This remote sensing data infusion improves the accuracy of soil moisture and snowmelt estimates by up to 16% and 24%, respectively, and it also improves the representation of vegetation anomalies relative to the reference crop fraction anomalies.

Remote Sensing from Different Sources for Crop Growth Monitoring in the Area of the Lower Northern Mississippi

Remote sensing monitoring of crop growth began from airborne photography to assist in crop pest management and has evolved into monitoring from satellites, manned aircraft, unmanned aerial vehicles (UAVs), and ground-based systems for crop production process modeling, optimization, and control. In recent years, for crop growth remote sensing monitoring, apart from satellites, manned aircrafts, and ground-based systems, UAVs have been developed and widely used for low-altitude remote sensing of crop fields to uniquely provide a cost-effective, flexible tool for field crop growth remote sensing. Additionally, their data create a critical layer between all other remote sensing platforms. This paper overviews the use of remote sensing from difference sources, especially airborne remote sensing from manned aircraft and UAVs, to monitor crop growth in the area of the lower northern Mississippi from the Mississippi Delta to the Black Prairie, one of the most important agricultural areas in the U.S. In this paper, three sites typical in the area are demonstrated for remote sensing monitoring of crop growth, and the issues and challenges are identified and discussed for future opportunities to integrate remote sensing data from different sources to improve crop monitoring in this area and surrounding areas.

Sparky and Rhonda Rucker at Govans Music Mondays

Sparky and Rhonda Rucker at Govans Music Mondays

Patient Centered Studies Focused on Type 2 Diabetes Management, Education, and Family Support: A Scoping Review.

Although a large amount of research has been conducted in diabetes management, many of the articles do not focus on patient-centered questions and concerns. To address this shortcoming, patients and various other stakeholders from three northern Mississippi communities co-created research questions focused on Type 2 diabetes management. To identify the diabetes management literature pertaining to each of the six patient-developed research questions from March 2010 to July 2020. A scoping review was conducted via PubMed to identify research articles from March 2010 to July 2020 focused on patient-centered Type 2 diabetes studies relevant to the six research questions. A total of 1,414 studies were identified via the search strategy and 34 were included for qualitative analysis following article exclusion. For one of the research questions, there were no articles included. For the remaining research questions, the number of articles identified ranged from two to eleven. After analysis of the included articles, it was found that these questions either lacked extensive data or had not been implemented in the practice of diabetes management. Additional research is warranted for three of the five questions, as current evidence is either lacking or contradictory. In the remaining two questions, it seems that adequate current research exists to warrant transitioning to implementation focused studies wherein data may be generated to improve sustainability and scaling of current programming.

Sedimentological and Geochemical Analysis of the Eocene Tallahatta Formation in Northern Mississippi, USA

The Eocene Tallahatta Formation forms part of the Tallahatta-Winona aquifer, which is part of the lower Claiborne confining unit of the Mississippi Embayment. A thorough understanding of the distribution of natural resources within the Tallahatta is limited by a lack of detailed studies at the outcrop and pore scales. In this study, we integrate particle size, petrographic, lithofacies, and geochemical analyses to interpret depositional environments, sequence stratigraphy, provenance, and diagenetic history from outcrops in Grenada County, Mississippi. Lithofacies include unprotected sand flat, tidal channel, open tidal mudflat, protected tidal flat, lower and middle shoreface, offshore transition, and offshore shelf settings. Lithofacies associations indicate that the Tallahatta consists of at least two parasequences within a falling stage systems tract (FSST). This is the first report on FSST strata from the Tallahatta Formation. Petrographic and geochemical results show that sediments were sourced from Precambrian Laurentian basement, recycled Appalachian basin sediment, and the Appalachian hinterland. Upsection changes in geochemistry represent an increase in contributions from recycled Appalachian basin sediment and progressive weathering of Acadian orogeny elements. Geochemistry also suggests that potentially economically important Ti-rich minerals are concentrated in tidal flat facies and scarce in shoreface facies. Primary porosity and bioturbation exert the greatest influence on the high porosity within many lithofacies. Early diagenesis also included detrital clay coating of framework grains, deposition of fecal pellets, minor chemical weathering, and hematite precipitation. Fecal pellets were altered to glauconite and opal cement was precipitated shortly after deposition or during early burial. Shrinkage of fecal pellets during glauconitization introduced minor moldic porosity. Limited burial produced minor physical compaction and only slightly reduced porosity. Abundant hematite precipitation during exhumation greatly decreased porosity locally.

Full Waveform Ambient Noise Tomography for the Northern Mississippi Embayment

AbstractWe use seismic ambient noise data recorded by broadband stations around the northern Mississippi Embayment to develop a three‐dimensional shear wave velocity model with full waveform inversion. Empirical Green's functions at periods between 8 and 40s are extracted using a data processing flow based on the continuous wavelet transform. Synthetic waveforms are calculated with an isotropic model through a Graphics Processor Unit‐enabled, collocated finite‐difference code. Starting from the Central United States Velocity Model, the shear wave velocity is iteratively updated with sensitivity kernels constructed using the adjoint method. Several mid‐crustal velocity variations are related to major geological features including the Mississippi Valley graben (MVG), the Ouachita thrust belt, and the Missouri batholith. An intrusion is imaged in northwestern Alabama, coincident with a previously unexplained gravity high. A major change in mid‐crustal velocity occurs across the MVG; much higher velocity crust is present southeast of the graben than northwest. The high velocities are attributed to numerous igneous intrusions, possibly related to formation of the Granite‐Rhyolite province. A strength contrast produced by the change in mid‐crustal velocities may have facilitated formation of the younger, shallower MVG, as external stresses became tensional during Iapetus rifting. The rift pillow is interpreted as the deeper expression of the high velocity crust. Low velocity crust is present below southern Missouri starting at a depth of roughly 20 km. The boundary between the low velocity crust and higher velocity crust to the south and east is sharp and coincides with the Nd‐line.

Late Cretaceous sediment provenance in the eastern Gulf Coastal Plain (U.S.A.) based on detrital-zircon U-Pb ages and Th/U values

ABSTRACT Detrital-zircon U-Pb geochronology documents a regional- to continental-scale drainage reorganization along the eastern Gulf Coastal Plain (USA) from the Late Cretaceous (Cenomanian) to the Paleocene–Eocene. We present detrital-zircon U-Pb ages and Th/U values from the Maastrichtian Ripley Formation to determine the sedimentary provenance and to provide spatiotemporal resolution of drainage reorganization. The Ripley Formation contains a 12.7% overall average abundance of detrital zircons with low (&amp;lt; 0.1) Th/U values relative to the underlying Cenomanian Tuscaloosa Group (3.6%), the overlying Paleocene–Eocene Wilcox Group (2.8%), an Appalachian foreland composite (2.1%), and the laterally equivalent McNairy Sandstone in the northern Mississippi Embayment (3.8%). Multidimensional scaling of detrital-zircon U-Pb spectra shows that the Ripley Formation is dissimilar from underlying and overlying Gulf Coastal Plain units, the McNairy Sandstone, and an Appalachian foreland composite sample because of differences in proportions of Appalachian (490–270 Ma) and Grenville (1250–900 Ma) zircons. We interpret the southern Appalachian Piedmont province as the principal sediment source region for the Ripley Formation to account for the elevated abundance of grains with low (&amp;lt; 0.1) Th/U values and unique detrital-zircon U-Pb age spectra. Results suggest a regional-scale (105 km2) drainage network, which delivered sediment to the Maastrichtian coast followed by northwestward littoral transport and eventual mixing with Appalachian foreland-derived sediment in the northern Mississippi Embayment. This study further brackets drainage reorganization along the eastern Gulf Coastal Plain and demonstrates how simple chemical–age relationships, such as zircon Th/U values coupled with U-Pb ages, can be used to evaluate sediment provenance.

Field Scale Assessment of the TsHARP Technique for Thermal Sharpening of MODIS Satellite Images Using VENµS and Sentinel-2-Derived NDVI

Remotely sensed-based surface temperature is an important tool for crop monitoring and has great potential for improving irrigation management. However, current thermal satellite platforms do not display the fine spatial resolution required for identifying crop water status patterns at the field scale. The thermal sharpening (TsHARP) utility provides a technique for downscaling coarse thermal images to match the finer resolution of images acquired in the visible and near infrared bandwidths. This sharpening method is based on the inverse linear relationship between vegetation fraction calculated from the normalized difference vegetation index (NDVI) and land surface temperature (LST). The current study used the TsHARP method to sharpen low-resolution thermal data from the Moderate Resolution Imaging Spectrometer MODIS (1 km) to the finer resolution of Sentinel-2 (10 m) and Vegetation and Environment New micro-Spacecraft (VENµS) (5 m) visible-near infrared images. The sharpening methodology was evaluated at scene and field scales in southern Georgia and northern Mississippi, USA. A comparison of sharpened temperature was made with reference temperatures from Landsat-8 Operational Land Imager (OLI) in four different spatial resolutions (30, 60, 120, and 240 m) for method validation. Coarse resolution comparison on the dates in which imagery from both sensors were acquired on the same day resulted in average observed mean absolute error (MAE) of 1.63 °C, and R2 variation from 0.34 to 0.74. Temperature errors at the field scale ranged from 0.25 to 3.11 °C using both Sentinel-2 and VENµS. Sharpened maps at 120 and 60 m resolution showed the highest consistency for all fields and dates. Maps sharpened using VENµS images showed comparable or higher accuracy than maps sharpened using Sentinel-2. The superior performance coupled with the better revisit time indicates that the VENµS platform has high potential for frequent in-season crop monitoring. Further research with ground data collection is needed to explore field use limitations of this methodology, but these results give useful insights of potential benefits of implementing the TsHARP technique as a tool for crop stress monitoring.

Seasonality of Aedes albopictus in North and Central Mississippi.

Container-breeding mosquitoes are increasingly important in public health due to recent outbreaks of Zika virus, chikungunya, and dengue. This paper documents seasonality of the most prevalent container-breeding mosquito species in Mississippi-Aedes albopictus. Ten sites in 5 counties in both northern and central Mississippi (20 sites, 10 counties total) were sampled by larval dipping and oviposition traps biweekly from September 2016 to June 2019, totaling 22 months and potentially yielding 440 egg or larval collections. However, 22 collections were missed due to inclement weather and personnel issues during the study period, so actually only 418 site visits were performed. Sites were chosen to maximize chances of finding Ae. albopictus. Of the total 1,310 mosquito larvae collected during the study period, 717 larvae and 50 positive egg papers belonged to Ae. albopictus. Aedes albopictus was found in all 10 northern and central counties. No eggs were collected at any of the sites from December through February, although larvae were occasionally collected during that time frame. This study demonstrates that Ae. albopictus is active in central and northern Mississippi beginning in March each year and continuing through November or December. There is little activity during the coldest months of the year (January and February). These data represent the first extensive analysis of Ae. albopictus seasonality in Mississippi, and as such, allow for better public health awareness of diseases transmitted by this species and design of more effective vector control programs.

Impacts of increasing fine fuel loads on acorn germination and early growth of oak seedlings

BackgroundPrescribed fire is increasingly used to restore and maintain upland oak (Quercus L. spp.) ecosystems in the central and eastern US. However, little is known about how prescribed fire affects recently fallen acorns under different fine fuel loads, which can vary with stand composition and basal area, burn season, and fire frequency. We conducted plot-level (1 m2) burns in an upland oak stand in northern Mississippi, USA, during December 2018, using single (i.e., ambient), double, and triple fine fuel loads, representative of those in nearby unburned and recently fire-treated, closed-canopy stands. Pre burn, we placed 30 acorns each of white oak (Quercus alba L.) and Shumard oak (Quercus shumardii Buckley) ~1 cm below the litter surface in five plots of each fuel treatment. Immediately post burn, we planted unburned and burned acorns in a greenhouse. After ~50% of each species’ unburned acorns germinated, we measured percent germination and height, basal diameter, and leaf number of germinating seedlings weekly for 11 weeks. Then, we harvested seedlings to determine above- and belowground biomass.ResultsThe single fuel treatment reduced acorn germination rates of both species to ~40% compared to ~88% in unburned acorns. When burned in double and triple fuel loads, acorns of both species had a <5% germination rate. There was no difference in basal diameter, leaf number, or biomass of seedlings from burned versus unburned acorns for either species. However, seedlings originating from burned acorns of both species were ~11% shorter than those from unburned acorns. Thus, both species responded similarly to fuel load treatments.ConclusionsAcorns of both species exhibited greater survival with lower fine fuel loads, and consequently lower percent fuel consumption. Acorns germinating post fire generally produced seedlings with growth patterns similar to seedlings originating from unburned acorns. These findings indicate that regular, repeated prescribed fires or canopy reductions that limit fine fuel accumulation and create heterogeneous fuel beds are likely to increase acorn germination rates relative to unburned sites or those with recently introduced fire.