This study shows that fire had a strong short-term effect on the small-sized individuals in the understory of two dry upland vegetation types, sandhill and upland pine. Large trees were less affected than saplings and small trees. The changes in these types were mainly structural rather than compositional. The influence of fire diminished toward the wet end of the vegetation gradient. Post-fire recruitment via resprouting and germination from seeds was rapid. The interaction of fire and vegetation type was apparent in the comparison of the two dry upland types with slope types. Simulation of fuel and fire provided additional, although not very strong, support for the existence of differences in fire behavior corresponding to an environmental gradient from dry upland forests to mesic and wet slope forests. Ordination using pre- and post-fire data suggests that fire had limited effects on current vegetation patterns and there was no indication that any present pre-fire type would be converted to another type. Furthermore, there were no clear convergent or divergent patterns in overall vegetation change; hence it was difficult to predict long-term changes. An eight-year record of vegetation change at a tornado damaged savanna site in Hickory Creek Unit demonstrates that the tornado had resulted in the succession of the vegetation toward a midslope forest, but two prescribed fires partially reversed such a trend. Phytolith analysis revealed that upland pine and some upperslope forests had abundant grass phytoliths. This indicates that these types had a grass component in the past under an open canopy which might have disappeared as a result of fire suppression, logging, and encroachment of shrubs and hardwoods.

This thesis analyzes, modifies, and defends Baruch A. Brody's theory of pluralistic casuistry as the best contemporary theory of animal and environmental ethics. In the course of reviewing lots of theories of animal and environmental ethics, two problems emerge: "inclusiveness" and "derivability." Unlike the other theories, pluralistic casuistry resolves the two problems. The argument begins by analyzing several cases that give evidence (intuitive case data) that moral theories should include in appropriate ways nonhuman animals, plants, and inorganic things. Next, important recent theories of three types are critically analyzed: (1) utilitarian theories (John Passmore, Peter Singer, and intrinsic-value utilitarianism); (2) deontological theories (Paul Taylor's theory of respect for life, sentience deontology, Tom Regan's theory of animal rights, and Holmes Rolston's theory of duties based on intrinsic-value), and (3) virtue theories (Stephen R. L. Clark, J. Baird Callicott, and Thomas E. Hill, Jr.). These theories fail in two ways: (a) they include too little or too much, or both (the "inclusiveness" problem); and (b) they fallaciously attempt to derive duties directly from values (the "derivability" problem). When emended as proposed in the thesis, Brody's theory of pluralistic casuistry resolves the inclusiveness and derivability problems. First, inclusiveness of nonhuman animals, plants, and inorganic things is achieved by casuistry's five major moral appeals (consequences, rights, respect, virtues, and justice). As argued by W. D. Ross (1930) and Brody (1979, 1988, 1998), pluralism is necessary because no single principle or monistic standard coherently encompasses all of the legitimate moral cases and principles. Pluralistic casuistry resolves the derivability problem by making explicit the empirical aspects of the case and by invoking one or more of the five major appeals. Ethics begins and ends with a case: the case's moral problem, and the moral decision resolving the problem. When more than one appeal applies, a conflict results. Conflicts are resolved by a holistic moral judgment. In contrast to other theories, pluralistic casuistry explains conflicts and gives detailed guidance for resolving conflicts.

A bottomland hardwood forest stand located in east Texas experienced a hurricane-related flood event in 1989. After this event, Carpinus caroliniana Walt. had a large pulse in mortality, decreasing dramatically in abundance (47%) over a 5-year period. The decline was greater at low elevations suggesting that at least part of the mortality was related to flooding. The flood was the longest summer flood on record. The duration of this growing season flood may have been partly a consequence of upstream dam management. Linear regression showed that in areas where Carpinus death was greater, several sapling species had increases in basal area growth. The invasive species Sapium sebiferum (L.) Roxb. had the greatest increase. This suggests that the Carpinus death and concomitant increase in light availability resulted in accelerated invasion of this forest by Sapium.

The invasive Chinese tallow tree (Sapium sebiferum) is difficult to control because of its large seed bank and ability to resprout from cut stumps. I performed laboratory and field experiments to evaluate the effectiveness of mulching live trees for restoring invaded prairies. Herbicide use was limited to manual application to cut stumps. I manipulated mulch depths and types in the field and measured soil temperatures beneath them. At depths of as little as 5 cm, Sapium mulch damped soil temperature fluctuations and reduced seedling emergence. Reduced seedling emergence was not the result of allelopathic compounds in Sapium mulch because other mulch types suppressed emergence similarly. Substantial regrowth of native vegetation occurred through the mulch. Independent manipulations of mulch depth and temperature fluctuations in a lab experiment confirmed that mulch suppressed seed germination indirectly via soil temperature effects. This prairie site can now be managed by mowing or burning.

A mixed pine-oak forest in the Hickory Creek unit of the Big Thicket National Preserve was hit by a tornado in December of 1983. Subsequently the forest was subjected to three prescribed fires in an effort to restore this area to its former savanna state. The tornado has allowed for both pines and oaks to regenerate. Both groups have regained much of the basal area lost in the tornado. However, the biggest compositional change has occurred at the understory level. There has been a huge increase in the upland shrub Ilex vomitoria (yaupon). Vegetation composition and density seem to be involved in a positive feed-back loop with fire. Plots dense with shrubs experienced low flame heights, which has allowed for increased shrub growth. This process seems to be leading the tornado plots down a spiral towards unflammability. The current fire regime of periodic winter fires has only been able to slow this process in the most open plots. A more intense use of fire, such as repeated summer burns appears to be necessary to reclaim this area as a fire-dependent savanna.

Despite a 20 year reintroduction effort into northeastern North Carolina, little is known about the natural history and ecology of red wolves (Canis rufus). In 2005, I studied home ranges, habitat use and pup attendance of red wolves during the pup rearing season. Data indicated that red wolves have home range sizes intermediate between those of coyotes (Canis latrans) and gray wolves (Canis lupus). Similar to other canids in the eastern United States, red wolves preferred to use extensive agricultural fields during the summer months rather than adjacent wooded areas. Red wolves abandoned dens early to move pups into adjacent agricultural fields. Consistent with pup rearing studies done on gray wolves, red wolf pups were rarely left alone indicating that red wolves share duties of pup rearing and that males play a significant role in the rearing of red wolf pups.

<p>Invasive fishes frequently change natural aquatic habitats due to predation and competition. The Alaska blackfish (Dallia pectoralis) is indigenous to some regions of Alaska but was illegally introduced to the Cook Inlet Basin in the 1950s. By the 1970s, fisheries managers expressed concern over possible ecosystem-altering effects of the blackfish introduction, especially in waterbodies containing popular sport fish. Descriptive food habit studies may assist fisheries managers in making decisions regarding management of non-native populations of Alaska blackfish. This project characterizes diet of three Cook Inlet Basin Alaska blackfish populations through stomach contents analysis. Shifts in diet across season, sex, and size of individuals from a lake, wetland pond, and stream are discussed using the Index of Relative Importance. Cook Inlet Basin Alaska blackfish consume similar invertebrate prey as native juvenile salmonids and stickleback, with major prey consisting of epiphytic/benthic dipteran larvae, gastropods, and ostracods. Piscivory, including cannibalism, is infrequent in these populations. Due to the high degree of dietary overlap with native fishes and stocked sport fish, and evidence that many Cook Inlet Basin waterbodies contain established populations of Alaska blackfish, fisheries managers should take actions to restrict the spread of blackfish through public awareness education, law enforcement, and funding for additional research. An Alaska blackfish husbandry manual outlines closed-system rearing and artificial fertilization protocols useful to researchers and educators for keeping live Alaska blackfish in the laboratory and classroom, in order to add to our body of knowledge about this species.

<p> Limited survey data and numerous anecdotal accounts indicate that the Common Nighthawk <i>(Chordeiles minor)</i> is experiencing population declines in Wisconsin. However, the magnitude of the decline is unclear because current avian monitoring efforts are not conducted at dusk when Common Nighthawks are most active nor do they specifically target urban areas such as cities and villages where Common Nighthawks are known to nest on flat graveled rooftops. New urban, crepuscular monitoring methods are needed in order to gain a better understanding of current Common Nighthawk demographics in Wisconsin. </p><p> The goal of this thesis was to conduct a baseline study using citizen science &ndash; based methodology to determine where Common Nighthawks persist in cities and villages in southeastern Wisconsin. The objectives of the study were to collect information on environmental factors, landscape features, and land cover types of potential importance to Common Nighthawks during the breeding season and then analyze the data collected to investigate correlations between each variable and Common Nighthawk occurrence at each survey point. The aim was to use the findings of the baseline study to inform current avian monitoring efforts such as the Wisconsin Nightjar Survey so that adjustments allowing for more effective monitoring of Common Nighthawks could be implemented in survey route placement and survey protocol. </p><p> Between June 7th and July 18th 2013, volunteers conducted 1,412 surveys at 494 points in 82 cities and villages within the Southeast Glacial Plains and Southern Lake Michigan Coastal ecological landscapes of Wisconsin. Common Nighthawks were detected in 98 surveys at 68 points in 32 cities and villages. On three different evenings at each point, volunteers conducted 10 &ndash; minute point counts in which they counted Common Nighthawks and described their behavior. During surveys, volunteers recorded the temperature ( &deg; F), estimated the moon phase, rated the sky condition, wind speed, noise, light pollution, and insect activity, and counted the number of potential Common Nighthawk predators (e.g. crows, gulls, raptors, and cats), and the number of Chimney Swifts. Volunteers also counted sources of artificial ambient light (e.g. street lights and stadium lights) and flat rooftops surrounding (100 meter buffer) the survey point. </p><p> The land cover surrounding each survey point (500 meter buffer) was analyzed from the National Land Cover Database (NLCD) 2011 using Geographic Information Systems (GIS). The number and total area of flat graveled rooftops surrounding each point (500 meter buffer) were estimated from aerial photos taken in 2011 using GIS. Results from statistical analysis of land cover classes suggests that in cities and villages, Common Nighthawks are more likely to be found in areas with higher percentages of impervious or built-up land cover. Agricultural land cover was the only land cover class that demonstrated a statistically significant negative correlation with Common Nighthawk presence. Strong, statistically significant positive correlations were found between Common Nighthawk presence and both the number of flat graveled rooftops and the total area of flat graveled rooftops. </p><p> Mann -Whitney U analysis of environmental variables recorded by volunteers suggests a statistically significant negative correlation between Common Nighthawk presence and percent moon illumination. A statistically significant positive correlation was also found between Chimney Swift <i>(Chaetura pelagica) </i>, counts and Common Nighthawk presence. A statistically significant positive correlation was also found between Common Nighthawk presence and the two landscape features measured by volunteers (100 meter buffer) &ndash; the number of flat rooftops, and the number of sources of artificial ambient light. </p>

<p> Limited information exists on how southern Californian restored estuaries affect fish habitat use. I used the movements of five predatory fishes in two guilds (ambush and roving predators) to assess juvenile habitat use within estuaries and across landscapes at two spatial scales. Translocating fishes between two discrete estuaries located approximately I 0 km apart revealed that connectivity potential between sites differed between foraging guilds. Despite habitat design differences, fishes did not appear to prefer one site over the other. However on a smaller scale (e.g., within a single estuary), differences in microhabitat conditions affected the habitat use by California Halibut (<i>Paralichthys californicus</i>). Individuals selected habitat based on water flow velocity, temperature and eelgrass coverage, but utilized habitat conditions in a size-segregated manner. Since restoration habitat design influences available microhabitat conditions, differences in design likely alters space use within restored estuaries although perhaps not estuary selection itself.</p>

<p> Benthic macrofauna can play an important role in facilitating some of the microbial mediated processes of nitrogen cycling in estuarine sediments. Declines in benthic macrofauna, like polychaete worms, have been attributed to long-term increases in bottom water hypoxia in Chesapeake Bay. Utilizing a large monitoring dataset including benthic macrofaunal abundance, biomass, and concurrent measures of environmental parameters, I examined how environmental conditions regulate the densities of opportunistic polychaetes in a mesohaline estuarine system. This analysis points to a benthic community dominated by euryhaline, opportunistic polychaete worms (<i>M. viridis, S. benedicti, H. filiformis, A. succinea</i>) which have well adapted but varying responses to hypoxia and other stressful conditions. Results of two laboratory experiments with the opportunistic polychaete <i>Alitta (Neanthes) succinea</i> were used to quantify the short-term influence of density and size of surface-feeding polychaetes on sediment-water fluxes of inorganic nitrogen under varying oxygen conditions. Polychaete enhancements of O₂ and nitrogen fluxes were strongly correlated with total animal biomass. Solute fluxes were stimulated by presence of both larger and smaller worms, but per capita effects were greater for the deep-burrowing larger polychaetes. Utilizing a unique large-scale monitoring dataset collected in the Chesapeake Bay, I employed Classification and Regression Tree (CART) and multiple linear regression (MLR) analyses to assess the relationship between benthic biomass and NH₄⁺ efflux within different regions of the estuary by season. In addition to labile organic matter, oligohaline and mesohaline tributary temperature and salinity control the rate of nitrogen cycling and benthic macrofaunal biomass. In deeper regions of mesohaline tributaries and the mainstem Bay, dissolved oxygen was found to be the dominating parameter regulating sediment nitrogen pathways as well as the structure of the benthic macrofaunal community. With increased macrofaunal biomass, spring regressions indicated an enhancement of NH₄⁺ efflux. In contrast, fall regressions indicated the enhancement of fixed nitrogen removal from sediments. Summer data lacked a significant relationship, but high NH₄⁺ effluxes under hypoxic/anoxic conditions suggested dissolved oxygen is the primary driver of summer nitrogen cycling. This study, using field and laboratory data, concludes that a complex balance between seasonal and regional dissolved oxygen, temperature and salinity conditions shape not only the benthic community but also the relationship between macrofaunal biomass and sediment nitrogen flux in this eutrophic estuarine system.</p>