Over the past 100 years, riparian vegetation communities throughout the Southwest United States have been extensively invaded by Tamara spp. (saltcedar). Saltcedar derives its common name from its physiological adaptation to excrete salts. The production of Tamarix detritus with associated secondary chemicals may affect the quality of aquatic invertebrate food and habitat resources. An alteration in food and habitat quality may affect the composition and structure of aquatic invertebrate assemblages. A series of experiments was conducted contrasting aquatic invertebrate assemblage densities, colonization rates, and growth rates associated with Tamarix versus native vegetation, Populus fremontii (cottonwood) and Salix exigua (willow), to determine if aquatic invertebrate assemblages have been altered by the invasion of Tamarix. Results of invertebrate growth rates over 13 weeks indicate that Tamarix is minimally different in food quality to cottonwood and willow. I failed to find differences in invertebrate colonization rates or invertebrate assemblage densities associated with Tamarix compared to cottonwood and willow over two 6-week time periods.

Indiana University-Purdue University Indianapolis (IUPUI) / While computed tomographic angiography (CTA) has emerged as a powerful noninvasive option that allows for direct visualization of arterial stenosis(AS), it cant assess the hemodynamic abnormality caused by an AS. Alternatively, trans-stenotic pressure gradient (TSPG) and fractional flow reserve (FFR) are well-validated hemodynamic indices to assess the ischemic severity of an AS. However, they have significant restriction in practice due to invasiveness and high cost. To fill the gap, a new computational modality, called InVascular has been developed for non-invasive quantification TSPG and/or FFR based on patient's CTA, aiming to quantify the hemodynamic abnormality of the stenosis and help to assess the therapeutic/surgical benefits of treatment for the patient. Such a new capability gives rise to a potential of computation aided diagnostics and therapeutics in a patient-specific environment for ASs, which is expected to contribute to precision planning for cardiovascular disease treatment. InVascular integrates a computational modeling of diseases arteries based on CTA and Doppler ultrasonography data, with cutting-edge Graphic Processing Unit (GPU) parallel-computing technology. Revolutionary fast computing speed enables noninvasive quantification of TSPG and/or FFR for an AS within a clinic permissible time frame. In this work, we focus on the implementation of inlet and outlet boundary condition (BC) based on physiological image date and and 3-element Windkessel model as well as lumped parameter network in volumetric lattice Boltzmann method. The application study in real human coronary and renal arterial system demonstrates the reliability of the in vivo pressure quantification through the comparisons of pressure waves between noninvasive computational and invasive measurement. In addition, parametrization of worsening renal arterial stenosis (RAS) and coronary arterial stenosis (CAS) characterized by volumetric lumen reduction (S) enables establishing the correlation between TSPG/FFR and S, from which the ischemic severity of the AS (mild, moderate, or severe) can be identified. In this study, we quantify TSPG and/or FFR for five patient cases with visualized stenosis in coronary and renal arteries and compare the non-invasive computational results with invasive measurement through catheterization. The ischemic severity of each AS is predicted. The results of this study demonstrate the reliability and clinical applicability of InVascular.

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Some of the most problematic agricultural weeds found in the Midwest United States are found in the Amaranthaceae family, such as Amaranthus palmeri and A. tuberculatus. These summer annual weeds are troublesome due to their competitive ability, high seed production, and resistance to herbicides from several modes of action which complicates management in field crops and has led to significant yield loss. Achyranthes japonica and Iresine rhizomatosa are two perennial species in the same family as A. palmeri and A. tuberculatus that occur in similar habitats as one another, but differ in invasiveness. Achyranthes japonica is a non-native, invasive species that is becoming a threat to forested areas and has been observed along agricultural field margins. Iresine rhizomatosa also occurs in forest habitats but is an endangered species in Illinois. This research seeks to determine the comparative life history and relative competitiveness of closely related weedy species when challenged with a dominant species. Specifically, select, closely related weedy species in the Amaranthaceae plant family that occur in southern Illinois were compared, i.e., Achyranthes japonica, Amaranthus palmeri, Amaranthus tuberculatus, and Iresine rhizomatosa. The first study examined the life history characteristics of A. japonica in regards to survivorship, growth and fecundity at two sites in southern Illinois (Chapter 2). Achyranthes japonica is a relatively new invasive species that has been poorly studied. This experiment showed that regardless of site, environmental factors had a significant effect on seedling emergence and seed viability, which decreased from 2012 to 2013 during a drought year and rebounded from 2013 to 2014 following flooding. On average, individuals at the driest site had higher performance and fecundity, regardless of year. The second experiment tested the relative competitive effect and response of the Amaranthaceae species to Glycine max, first in a greenhouse study that tested shading and nitrogen resource drawdown for each species, and second in a controlled field experiment that tested intraspecific competition (Chapter 3). In addition, A. japonica seedlings were planted as either unmanipulated seedlings (uncut A. japonica) or as a seedling cut back to the soil surface at the four-node stage (cut A. japonica) at which point seedlings have reached a perennial growth stage. The greenhouse experiment showed that the four species each drew down light significantly, but not nitrogen. Shading decreased the aboveground biomass of the species in comparison to unshaded controls. Supplemental nitrogen, however, increased the aboveground biomass of A. palmeri and A. japonica. The supporting controlled field experiment showed that the competitive response of the weed species to the presence of G. max showed a reduction in height compared to the weed species grown in monocultures. Glycine max and the weed species, except I. rhizomatosa, showed a similar competitive effect and response when aboveground biomass was measured. Achyranthes japonica attained the highest belowground biomass when grown as a monoculture and in the presence of G. max. A competitive effect ranking was determined to be A. palmeri > A. tuberculatus > cut A. japonica = uncut A. japonica = I. rhizomatosa with the competitive response ranking being the inverse. The third study implemented an integral projection model (IPM) to determine the population growth rate of each species and how they compared to one another (Chapter 4). This experiment showed that A. palmeri, A. tuberculatus and A. japonica each had a population growth rate greater than one indicating rapidly growing populations. By contrast, I. rhizomatosa had a population growth rate less than one indicating a declining population. The results suggest that A. japonica has not yet shown the ability to escape management strategies in agricultural fields implemented by farmers, but it is still an aggressive invasive species that farmers and land owners need to be able to identify. This species has many similar characteristics to the Amaranthus species, such as the ability to colonize in areas with limiting resources, continual flushes of germination throughout the growing season, the ability to outcompete other weed species, and high fecundity but, A. japonica also is a perennial species that can withstand removal of shoot material and has a high germination rate. Based on these results, only early detection and rapid response methods should be relied on to keep these species out of areas in and around agricultural fields. Iresine rhizomatosa’s performance in these studies was consistent with its rarity.

Non-native macrophytes structurally impact aquatic assemblages, yet little is known regarding how they influence energy pathways in freshwater ecosystems. Allelopathy in Eurasian watermilfoil- Myriophyllum spicatum has been shown to target basal epiphytic organisms resulting in differences in assemblage structure of colonizing epiphyton between M. spicatum and native M. sibiricum. I conducted a growth chamber experiment to investigate the hypothesis that differences in assemblage structure of colonizing epiphyton between these two macrophytes influence trophic dynamics within aquatic systems. My data suggest M. spicatum produces higher concentrations of allelochemicals, resulting in a more diverse epiphytic assemblage compared to M. sibiricum. This could result in potential transformation of trophic dynamics by decoupling carbon as it flows from primary producer to primary consumer. This work identifies a contributing mechanism responsible for M. spicatum invasiveness and provides new insight in its ecology and management of this non-native macrophyte.

The presence and spread of invasive tree species have caused great ecological and economic damages. Previous studies usually ignored the role of socioeconomic factors and seldom treated presence and abundance as different phenomena. Using Classification and Regression Trees (CART) analysis, important driving factors affecting the presence and abundance of invasive tree species in Mississippi were identified. Then these selected important factors were spatially analyzed using a spatial lag model at the plot and county levels. The empirical results from the spatial lag model showed that: 1) presence was associated with elevation, ownership, population density and per capita annual income; 2) abundance was related to stand age, elevation, growing stock and per capita annual income. These findings suggested that socioeconomic factors besides ecological factors played a significant role and factors affecting the presence and abundance were different. Thus, management prescriptions to monitor and control invasions should depend on difference factors.

The legislative procedures regarding wild pigs in the United States are expanding in scope and priority, however, the uniformity of legislation is entropic at best. Each state addresses the issues of wild pigs differently and treatment is based on a priority of resource concerns. An evaluation was conducted at the national level of federal, state, and local policy with regards to wild pig control. Additionally, successful and unsuccessful legislation is evaluated to determine commonalities in the social, economic, and ecological factors contributing to the success or failure of legislation. Information collected provides state legislatures with sample model legislation that can be passed with the support of stakeholders and the citizenry, as well as help guide states into a more uniform system of policy. Furthermore, it provides states without, or with low populations of wild pigs, a proactive suite of legislation to prevent further spread and facilitate eradication of localized populations.

Former researches provide evidence that invasive species could alter ecosystem’s components, threaten native species and cause economic losses in southern forest lands. The objective of the project is to explore significant driving factors and develop geospatial models for monitoring, predicting and mapping the extent and conditions of major invasive species. In the study area, 16 invasive species were classified into four groups: regionally spreading species, regionally establishing species, locally spreading species and regionally colonizing species by population size and spatial characteristics. According to local Moran’s I, spatial autocorrelation existed in 16 invasive species. Autologistic model and simultaneous autoregressive model were employed to explore the relationships between spatial distribution and a set of indentified variables for Chinese privet, kudzu, Nepalese browntop and tallow tree at plot and county levels. The project showed that human-caused disturbances and forest types were significantly related to the spatial distribution of four invasive species in different scales.

Herbicides were evaluated for control of non-native and invasive plants namely tropical soda apple (TSA) (Solanum viarum), tropical spiderwort or Benghal dayflower (Commelina benghalensis), and Italian ryegrass (Lolium multiflorum) from 2007 to 2012 in greenhouse at Plant Science Research Center, Mississippi State University, Starkville-Mississippi. In TSA study, aminopyralid at 0.88 or 0.12 kg ae/ha, and triclopyr + picloram + 2,4-D at (0.56 + 0.15 + 0.56) kg ae/ha controlled TSA seedlings emergence ranged from 83 to 96% at premergence (PRE), and 1 month after treatments (MAT). All herbicides failed to provide more than 63% control of TSA at 3 and 6 MAT. In Benghal dayflower study, bentazon, bromoxynil, chlorimuron ethyl plus tribenuron methyl, dimethenamid-P, nicosulfuron plus rimsulfuron, primisulfuron-methyl, S-metolachlor plus glyphosate plus mesotrione, and sulfosulfuron provided less than 50% control of Benghal dayflower during 6 weeks of evaluation whereas other herbicides: aminocyclopyrachlor (34-96%) ametryn (2-55%), atrazine (2-68%), diclosulam (12-67%), flumioxazin (59-83%), saflufenacil (24-78%), and sulfentrazone (67-96%) provided variable control of Benghal dayflower. In Italian ryegrass study, 50 seeds of F1 generation of resistant biotype ’49E’ and susceptible biotypes ‘Gulf’ and ‘Marshall’ of Italian ryegrass which were previously grown in mixture were used. Each biotype’s F1 generation responce to imazapyr at 0, 1, and 2% under PRE, early post emergence (EPOST) and late postemergence (LPOST) was evaluated. At PRE, imazapyr at 1 and 2% reduced ‘49E’ seedlings emerged 3 and 18%, respectively, but both rates failed to have any significant impact on fresh biomass weight compared to untreated. At EPOST, survival of ‘49E’ shoots were reduced 3 to 10% by both rate of imazapyr whereas only imazapyr at 1% caused 0.74 to 3.8 % fresh biomass reduction. At LPOST, ‘49E’ shoot survival was reduced 9 to 12% by both rate of imazapyr whereas both rate of imazapyr reduced ‘49E’ fresh biomass 3 to 31%. In all the PRE, EPOST, and LPOST experiments, ‘Gulf’ and ‘Marshall’ were still susceptible to the imazapyr.