Partners in Flight (PIF) recommends using silviculture to improve breeding habitat conditions for migrant landbirds. Alternative thinning treatments may benefit priority landbird species by increasing structural complexity in second-growth forests. However, the effects of thinning on landbird populations in oak (Quercus spp.)-hickory (Carya spp.) forests have not been experimentally demonstrated. I used a randomized and replicated large-scale manipulative experiment to evaluate the effects of thinning (i.e., crown-release and gap creation) on forest habitat characteristics and avian populations at the Tennessee National Wildlife Refuge. I collected data during 2001 (pre-treatment) and from 2002 to 2005 (1 to 4 years post-treatment) in 20-ha thinned (n = 8) and control (n = 4) plots. Using mixed model ANOVA with covariates, I compared habitat attributes, tree regeneration, avian population densities, daily nest survival rates, realized brood sizes (# fledged per successful nest), rates of brown-headed cowbird (Molothrus ater) brood parasitism, and nest-site characteristics between treatments. In addition, I used Program MARK to evaluate the influence of habitat factors at multiple spatial scales on predation rates of Acadian flycatcher (Empidonax virescens) and wood thrush (Hylocichla mustelina) nests. Forest habitat attributes, avian population densities, and nest survival rates did not differ between control and thinned plots prior to treatment, indicating my experimental design (including the random allocation of treatments to plots, blocking, and the interspersion of plots across the study area) was sufficient for detecting treatment effects. Thinning resulted in a 29% difference in basal area between treatments (thinned = 20.3 m2 ha-1; control = 28.5 m2 ha-1). Compared to controls, thinned plots had significantly less overstory cover and midstory cover and significantly more downed wood and herbaceous and woody vegetation in the lower forest strata. Specifically, I detected greater densities of oak (Quercus spp.), yellow-poplar (Liriodendron tulipifera), and sourwood (Oxydenrum arboretum) saplings, and greater cover in poison ivy (Toxicodendron radicans) and blackberry (Rubus spp.) in thinned than control plots. I used spot-mapping to estimate the densities of PIF priority species. Thinning had positive effects on the densities of seven species (eastern towhee [Pipilo erythropthalmus], eastern-wood pewee [Contopus virens], indigo bunting [Passerina cyanea], Kentucky warbler [Oporornis formosus], white-eyed vireo [Vireo griseus], yellow-breasted chat [Icteria virens], and yellow-throated vireo [Vireo flavifrons]), inconclusive or negligible effects on the densities of two species (Louisiana waterthrush [Seiurus motacilla] and worm-eating warbler [Helmitheros vermivorus]), and negative effects on the densities of two species (Acadian flycatcher and wood thrush). I monitored 1,149 nests of 28 species. Predation accounted for 80% of all nest failures. Mayfield-adjusted nest daily survival rates of all species combined did not significantly differ between treatments. For all species combined, rates of cowbird parasitism varied annually but did not significantly differ between thinned (20.8%, SE = 2.3) and control (18.5%, SE = 3.7) plots. I assigned bird species to functional groups for further analyses. PIF priority mature-forest species exhibited nest daily survival rates (0.972 vs. 0.969), realized brood sizes (2.8 vs. 2.6), and parasitism rates (16.9 vs. 10.4%) that were comparable between thinned and control plots. Based on 162 nests in thinned plots, PIF shrubland species had nest daily survival rates of 0.958, realized brood sizes of 2.9, and parasitism rates of 13.6%; this functional group nested too rarely in control plots for analysis. Treatment effects were significant for the overstory and midstory nesting functional groups. Overstory nesters exhibited nest daily survival rates that were greater in thinned (0.982) than control (0.963) plots. Midstory nesters experienced greater parasitism rates in thinned (30.0%) than control (17.9%) plots. I evaluated nest-site selection and factors affecting nest predation rates using 132 Acadian flycatcher and 112 wood thrush nests. In thinned plots, both species selected nest sites with greater overstory and midstory cover than found at random. I found little evidence that nest predation rates were influenced by the amount of agriculture in the local (314 ha) landscape or by distance to anthropogenic edge, perhaps because the landscape was predominantly forested (agriculture < 4%) and most nests were >350 m from an edge. In thinned plots, predation rates on wood thrush nests decreased with increasing overstory cover and increasing basal area in large trees; predation rates increased with increasing basal area in small-diameter trees. None of the habitat predictors I measured had a strong relationship to Acadian flycatcher nest predation rates in thinned or control plots. Model-averaged nest survival estimates for wood thrushes were 27.8% and 26.8% in thinned and control plots, respectively. Acadian flycatcher model-averaged nest survival estimates were 53.5% in thinned and 56.4% in control plots. In summary, my results indicate that thinning had strong effects on forest habitat attributes and the demographics of some priority bird species. In the short term (1 to 4 years post-treatment), thinning appears to provide suitable breeding habitat for priority bird species that prefer dense understory vegetation or partially-opened overstories for nesting. Conversely, thinning had neutral or negative effects on some species and functional groups that nest in midstory vegetation, indicating there may be an ecological cost, in the short-term, associated with implementing this treatment. This treatment likely will have differential costs and benefits for avian populations as forest habitat conditions continue responding via successional dynamics and vegetative growth to the initial thinning operation.

Four experiments were performed in a greenhouse or growth chamber to study the quantity and quality of flavonolignans in response to environmental stress in milk thistle (Silybum marianum L., Gaertn.). A preliminary experiment was conducted in spring 2004 to study effects of leaf harvests on growth, development, and flavonolignan content in milk thistle seeds. Taxifolin, a component of silymarin and precursor to flavonolignans, was significantly reduced due to leaf harvest treatments. The weedy nature (sporadic germination) of Silybum made germinating enough plants for experimentation problematic. Initial germination studies to determine imbibition and pre-chilling requirements were inconclusive due to heavy fungal infections. A sterilization procedure was chosen to treat seeds before experimental use and flavonolignan analysis. Germination trials were also performed with seven other seed sources. Seeds harvested in Croatia showed the best germination and were used for subsequent experiments. Flavonolignans in Silybum seeds are reported to vary depending on environmental conditions and genetic diversity within a population. In another experiment, total silymarin concentrations determined from eight seed sources from around the world ranged from 29.6 to 56.9 mg/gram of seed meal. Individual flavonolignans varied significantly in and among seed sources. In the first stress experiment was, plants were grown in pine bark media in polyethylene bags. Plant densities from 1-24 plants/bag were established. Immature and total seed counts and yields decreased with increasing density. Number of blooms per plant, bloom diameter, and mature seed count and yield were negatively correlated to density. There was no significant effect of plant density on flavonolignan content. In the second stress experiment, milk thistle plants were grown in perlite in polyethylene bags. Water treatments (200, 650, 1100, 1550, and 2000 mL/day including fertigation) were created using pressure-compensated emitters. The lowest watering rate significantly reduced stem height and bloom diameter. The highest water treatment showed the highest count of immature seeds. In primary blooms, the lowest water rate yielded the highest taxifolin concentration (0.89 mg/g). Flavonolignan content was not significantly affected in secondary blooms. Silybum growth and development was affected by environmental stress. However, no significant effect on silymarin concentration or composition was established.

Episodic stream acidification occurs as storm events temporarily reduce acid neutralizing capacity (ANC) and pH. Stream acidification is suspected to have damaging effects on the health of aquatic ecosystems and biota. The objectives of this research are to 1) characterize stream baseflow and stormflow chemistries in three watersheds in the Great Smoky Mountains National Park (GRSM), 2) understand potential mechanisms responsible for episodic acidification, and 3) understand the relationship between storm event magnitude, antecedent soil moisture condition, and the stream’s pH response. Three remote, forested, high-elevation streams (Middle Prong, Ramsey Prong, and Eagle Rocks Prong) were selected in the Middle Prong of the Little Pigeon River Watershed. Multi-parameter data sondes were installed at each site to record continuous stream data. Autosamplers were set up in connection with the sondes to collect samples during storm events. Stormflow, baseflow, and precipitation samples were analyzed for pH, ANC, and a broad spectrum of cations and anions that contribute to the ion balance. During stormflow, ANC and pH depressions were observed for all storms at each study site. Sulfate, nitrate, and organic acid concentrations increased during each storm. Base cation concentrations generally increased during stormflow at Middle and Ramsey Prongs, but diluted occasionally on Eagle Rocks Prong. The relative changes in ion concentrations were used to determine which ions (acids) were most responsible for ANC depression. ANC contribution analysis indicates acid deposition may be the primary cause of episodic acidification, but it appears organic acids and cation dilution may also contribute. Pyritic geology is also suspected to contribute to baseflow and stormflow acidity in the Eagle Rocks Prong. Data exploration indicates large storms preceded by long, dry periods cause the largest pH depressions. It appears stream acidification may be driven by acid deposition, but additional inputs from varying vegetation and geology create unique and complex response to the observed stream acidification.

Sediment is often listed as one of the main contributors to the impairment of surface waters throughout the United States. Sediment source identification is difficult in watersheds with complex combinations of land-uses and non-point sources because of the complexities involved in correlating water quality data, which are relatively easy to collect, to the source of a degrading component. The elemental properties of a particular soil on the landscape may be viewed as a “fingerprint”. A comparison of the elemental fingerprints of potential sources and in-stream sediment may be used to establish sediment source. The objectives of this investigation were to characterize the elemental content of suspended stream sediment and potential sources of sediment in an impaired watershed, Pond Creek watershed in east Tennessee (HUC: TN06010201013), and to use multivariate statistical techniques to identify and quantify sediment sources in the watershed. Potential sediment source samples were collected throughout the watershed and suspended sediment samples at two locations. Subsamples of the <53>μm material and suspended sediment were subjected to total dissolution, HNO3-extraction, and Mehlich 3-extraction. Descriptive statistics suggested that each dataset contained considerable heterogeneity. The source samples were grouped according to land management and position in the landscape. The results of a Kruskal-Wallis rank test and discriminant function analysis indicated that for all three datasets the elemental variability of the samples was not sufficient to differentiate the source and sediment samples and characterize the suspended sediment sources using the initial group definitions. When using all available elemental data from each dataset the groups defined by cluster analysis and canonical discriminant analysis did not match the contents of the initially defined groups. The composition of the clusters varied from one dataset to another, making it difficult to draw conclusions concerning the cluster contents, or to identify sources of suspended sediment. The lack of elemental content variability for differentiating the source and sediment samples and characterizing the suspended sediment sources is likely an artifact of the watershed sampling procedure that was employed, which was directed towards sampling sources likely to be contributing to the suspended sediment load in Pond Creek.

The value of air quality improvement following the 1990 Clean Air Act Amendments is estimated at the county level in the lower 48 United States. This study applies a hedonic model to assess the economic benefits of air quality improvement using an instrumental variable approach that combines geographically weighted and spatial autoregression methods to account for spatial heterogeneity and spatial autocorrelation. Positive amenity values of improved air quality are found in five major clusters of areas across Eastern Kentucky and most of Georgia around Southern Appalachian area, the State of Illinois, on the border of Oklahoma and Kansas, on the border of Kansas and Nebraska, and Eastern Texas. The reason for the clusters of significant positive amenity values may be due to the combination of intense air pollution, consumers’ awareness of diminishing air quality, and higher marginal benefit of reductions of TSPs in communities with relatively low pollution levels. Surprisingly, negative amenity values of improved air quality are found in the three distinctive clusters of east Virginia, west and central Texas, and southeast Montana. This unexpected result may be explained by worsening air quality with intensive economic growth, greater appreciation in housing prices in those regions, and/or missing variables reflecting regionally specialized economic growth.

A bacterial source tracking study using Bacteroides host associated real-time PCR assays was performed to determine the sources of fecal contamination in Pond Creek (HUC 06010201013). Pond Creek, located in the Ridge and Valley physiographic region in Eastern Tennessee, is a 303(d) listed stream that fails to meet water quality standards for pathogens. Water samples and discharge were measured monthly at eight locations from November 2005 to November 2006. Grab samples were analyzed for several chemical parameters and for microbial fecal indicator organisms, namely Bacteroides spp., Escherichia coli, and Enterococcus. The objectives of the study were to quantify total, human, and bovine associated Bacteroides. Additionally, we investigated spatial and temporal variation of fecal indicator organisms and created load duration curves for each sampling site. The results showed that Escherichia coli concentrations regularly exceeded water quality standards. Bacteroides host associated real-time PCR assays indicated that cattle were the dominant source of fecal pollution (99 percent of total Bacteroides). Although human-associated Bacteroides were detected, their concentrations remained relatively low across the watershed. Load data show that fecal contamination from bovine sources occurs at elevated levels throughout the watershed; no statistical differences between sites were observed for bovine associated Bacteroides (BoBAC) and Bacteroides spp. belonging to the Bacteroides genus (AllBAC) loads. Additionally, bovine-associated Bacteroides concentrations were very highly correlated (r2 = .903) with the total Bacteroides concentrations. Load Duration Curves (LDCs) also indicated extensive bovine fecal pollution. Load data separated into human and bovine LDCs showed that Escherichia coli loads from bovine sources were mostly flow dependent whereas human associated Escherichia coli loads were generally flow independent. Temporal variations followed seasonal weather patterns; mean loads of all fecal indicators, except Enterococcus, were greatest during the months of highest precipitation and lowest in the drier months. No temporal patterns were established for concentrations of fecal indicator organisms. This suggests that runoff transported the majority of fecal inputs to Pond Creek. Best management practices (BMPs) such as improving pastures, nutrient management, proper manure storage, controlling livestock stocking densities, vegetative filter strips, and riparian fencing with careful riparian grazing, should be implemented to reduce fecal inputs from cattle and help Pond Creek meet TMDL guidelines.

We investigated, under long-term no-till in western Tennessee, the effects of rotating the low-input crops cotton and soybeans with the high-input crop corn, compared to continuous monocultures of cotton and soybeans, and of using the winter cover crops (WCCs) winter wheat and hairy vetch, compared to winter fallow, on key indicators of soil health concerning vegetative cover and labile SOM. The line-transect method was used to measure percent vegetative cover. Dry weight of surface crop residue and aboveground living plant biomass (WCCs and winter weeds) was obtained. The living plant biomass was analyzed for carbon (C) and nitrogen (N) by dry combustion to determine C/N ratios. The sand-sized POM-C fraction at 0 to 5 and 5 to 15 cm was physically fractionated and analyzed for C by dry combustion. The inclusion of corn in rotation with cotton significantly increased aboveground crop residue quantity, aboveground winter weed biomass quantity, total aboveground biomass quantity, percent vegetative cover, and POM-C at 0 to 5 cm. The inclusion of corn in rotation with soybeans significantly increased aboveground crop residue quantity and POM-C at 0 to 5 cm, but significantly decreased aboveground winter wheat biomass quantity, total aboveground biomass quantity under winter wheat, aboveground winter weed biomass C/N ratio, and POM-C at 5 to 15 cm. The use of WCCs did not significantly increase total aboveground biomass quantity under most cropping sequences, and significantly reduced aboveground crop residue quantity, aboveground winter weed biomass quantity, and percent vegetative cover. The WCCs generally did not affect POM-C at either depth, though they significantly increased POM-C at 5 to 15 cm under continuous soybeans. Compared to winter wheat, hairy vetch significantly increased aboveground winter weed biomass quantity and percent vegetative cover. Our results demonstrate that the inclusion of corn in rotation with cotton is highly effective, while inclusion of corn in rotation with soybeans and the use of WCCs are ineffective in improving soil quality by increasing vegetative cover and the labile pool of SOM under these conditions.

Agricultural runoff is a leading non-point source contributor to water quality impairment in the United States and is associated with eutrophication of surface waters. Phosphorus (P) is often the most limiting nutrient for eutrophication in freshwaters. The objectives of this study were to characterize the P forms in surface runoff from an agricultural field that has received long-term applications of liquid dairy manure and to determine the forms of soil P that occur within a sinkhole feature located within the application field. Three 21-m x 6 m bermed plots were established to collect storm water runoff from a portion of the study site which drains into the sinkhole. The runoff collected was analyzed for total P (TP), dissolved reactive phosphorus (DRP), total dissolved P (TDP), dissolved organic phosphorus (DOP), and particulate P (PP). Soils were sampled from various elevations within the sinkhole feature and were analyzed for TP, total organic P (TOP), Mehlich-3 extractable P, and the maximum P sorption capacity. The results showed a precipitous increase in TP of surface runoff after manure application, from 2.2 g ha-1 to 21.9 g ha-1. The majority of P leaving the field as runoff prior to manure application was associated with the PP fraction (63% of TP). Surface runoff from two rainfall events occurring after diary manure was applied consisted predominately of DRP (67% of TP). Dissolved reactive P in runoff ranged from 0.02 to 0.2 mg L-1 before manure application and 7.1 to 17.1 mg L-1 after application. It has been reported that DRP concentrations in the low ìg/L range can negatively stimulate aquatic vegetation growth in P-limited waters, which indicates the runoff leaving the study site has the potential to impair water quality. A statistically significant difference existed for soil TP concentrations at different elevations within the sinkhole feature, ranging from 3116 mg kg-1 in the base to 914 mg kg-1 in the higher elevations of the sinkhole. A slight increase in TOP concentrations from the base (407 mg kg-1) to the higher elevations of the sinkhole (513 mg kg-1) occurred. The measured maximum P sorption capacity of soils within the sinkhole feature showed that these soils can potentially sorb between 284-379 mg kg-1 of P indicating that the soils are not P saturated and are capable of fixing additional P from runoff.

Laser-induced breakdown spectroscopy (LIBS) has been applied for the quantitative analysis of various samples, but it is controversial for chemically-complex soils. In order to study the effect of delay time, gate width, and repetition rate on the LIBS signal in soil, the emission line at 396.84 nanometer was selected. The results indicated that repetition rate, delay time, and gate width significantly affected the LIBS signal, delay time was more important than gate width in controlling the LIBS signal. The optimum instrumental parameters for soil analysis were obtained when repetition rate, delay time, and gate width equaled 10 hertz, 1 microsecond, and 10 microsecond, respectively. In order to compare the analytical ability of univariate and multivariate approaches in analyzing the LIBS spectral data and to quantitatively determine copper and zinc concentrations in soils, 12 samples with different copper and zinc concentrations were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and LIBS, respectively. The univariate and the partial least square (PLS) regression were coupled with LIBS to build the calibration models and to predict copper and zinc concentrations. The background-subtracted signal intensity at 324.75 nanometer (copper) and 334.59 nanometer (zinc) were used for the univariate analysis, and the full spectral range 200-600 nanometer and the reduced spectral ranges 250-450 nanometer and 300-350 nanometer were used for the PLS analysis. Copper and zinc concentrations predicted by LIBS were compared with those measured by ICP-OES. The results demonstrated that (1) the PLS regression was powerful in analyzing the LIBS spectral data, and compared to the univariate regression, it improved the normalized root mean square error of calibration (NRMSEC) about 15% and the normalized root mean square error of prediction (NRMSEP) about 10% respectively; (2) The PLS regression using the reduced spectral range (300-350 nanometer) containing copper and zinc peaks produced the best results among all the spectral ranges, which indicated that use of the suitable spectral range in the PLS regression improved the LIBS analytical ability; (3) The implementation of multivariate approaches in analyzing the LIBS spectral data made the quantitative analytical ability of LIBS promising and comparable to that of ICP-OES.

As the Earths climate changes, coastal communities are increasingly vulnerable to the natural hazards that are driven by these processes, particularly in regards to the health of these communities. It has been shown that disease patterns can change in response to our environment, putting the health resilience of communities at risk. This study looks at the relationship between natural exposure and traditional resilience index variables in the context of the spread of West Nile Virus along the Gulf of Mexico. Through analysis of 534 counties, the West Nile Virus for 2001-2012 was analyzed as an incidence and incidence rate at three levels of urban and rural classification (metropolitan, micropolitan, and rural) as well as for the entire study area. Regression analysis found that models incorporating both natural and society indicators were more successful at explaining a populations vulnerability to the West Nile Virus. It was seen that short-term climate variability and economic indicators were important measures of a communitys health resilience in the context of the prevalence of the West Nile Virus. Socio-economic characteristics proved to be more explanatory in rural environments while natural characteristics explained more variance in metropolitan and micropolitan environments. Increasing temperatures were found to increase the spread of the West Nile Virus, particularly in urban areas. This study is a tangible analysis of health resilience in the context of both the human and natural environments across different levels of human infrastructure on a large spatial scale.