No description available.

No description available.

<p> The practice of restoration has been called the acid test for ecological theories, as theoretical outcomes may or may not occur in real life scenarios. Regardless, the need for increased communication between theory and practice is necessary to mutually benefit both disciplines. My dissertation research used several major ecological theories to formulate questions regarding environmental constraints on the establishment and expansion of several species of freshwater tidal macrophytes (Schoenoplectus acutus, Schoenoplectus californicus, and to a lesser extent, Typha latifolia). I investigated the response of these species at different life-history stages to various environmental stressors (i.e., degree of soil compaction, flooding duration, and nutrient availability) in both field and controlled greenhouse settings. These studies revealed that adult individuals are more tolerant to environmental stressors than their rhizome or seedling counterparts. Schoenoplectus californicus exhibited superior performance than S. acutus or T. latifolia in when subjected to extreme flooding and stressful abiotic conditions. My research regarding silicon and nitrogen nutrient availability emphasizes the role that Si plays in sustaining Schoenoplectus spp., especially in the presence of high nitrogen concentrations. Finally, my research showed that the species of concern are powerful ecosystem engineers and are capable of ameliorating their abiotic conditions over time. The information presented in my dissertation research provides specific, useful information for freshwater tidal marsh restoration managers and emphasizes the utility of incorporating theory to improve our understanding and stewardship of ecosystems. </p>

<p>Within the San Francisco Bay Area, Western Snowy Plovers (<i>Alexandrinus nivosus nivosus</i>) nest and winter in former salt ponds. They face a number of threats including human-altered habitats and high levels of predation by mesopredators and raptors. The South Bay Salt Pond Restoration Project (the Project) is a large wetland restoration project that will change and potentially eliminate Snowy Plover habitat in the region. As the Project returns salt ponds to tidal wetland, there will be less of the dry, flat, and sparsely vegetated habitat that plovers need for breeding and wintering habitat. A greater understanding of the specific microhabitat requirements for high quality plover foraging sites is needed. In particular, it is important for managers to understand what constitutes high quality wintering habitat for Snowy Plover numbers. This study assessed the characteristics at sites where Snowy Plovers winter in former salt ponds, especially habitat traits related to promoting plover foraging. Analysis of plover foraging habitat showed that plovers were associated with increasing plant height, water cover, and distance from perches and levees. This information is designed to inform restoration and management decisions in efforts to meet Snowy Plover recovery goals in the South San Francisco Bay. </p>

<p> Erosion is a serious concern across the US and the globe. One effective method to reduce soil erosion is to apply rolled erosion control products (RECPs). One material source for use in RECPs that has not been studied is low-value forest residuals (LVRs). The objectives of this study were to design RECPs out of four LVRs (leaf litter, willow whiplets, willow chips, spruce needles) and to assess their ability to reduce soil loss, control water quality (turbidity and total phosphorous), and enhance germination. LVR RECPs were tested using ASTM standards on bare, detritus, and burned soils. Leaf litter and spruce needle RECPs were highly effective at all three abilities, while the willow whiplet and chip RECPs were effective at reducing erosion, but less effective at controlling water quality and enhancing vegetation. Overall, the use of LVRs as a material source for RECPs shows great promise.</p>

<p> Since European colonization, Appalachian culture has been based on resource extraction, such as coal mining, timbering, and Non-Timber Forest Product (NTFP) harvest. Surface mining degrades forest habitat for medicinal plants, especially the habitat for the internationally valuable medicinal herb, American ginseng (<i>Panax quinquefolius</i> L.), and the NTFP culture associated with this plant. The relationship between medicinal plant conservation and surface mining must be studied with a non- traditional, multi-faceted approach: culturally, economically, and ecologically. (1) Using community-based participatory surveys, I determined how ginseng harvesters and non- harvesters in West Virginia communities view the relationship between surface mining and ginseng harvest. Harvester culture is one worth preserving, as they value conservation. However, most harvesters admit to illegal harvesting practices. By determining what harvesters and non-harvesters prioritize and value, and understanding what is the most effective way to connect with these two groups, this research can aid in the development of successful environmental education and conservation outreach. (2) Challenging the perceptions that economic growth is incompatible with ecological consciousness, an economic analysis comparing the short-term gains of surface mining to the potential economic value of sustainable ginseng harvest or a large-scale ginseng farm operation was completed. Through an in-depth economic modeling approach I showed that stewarded ginseng harvest can be economically advantageous in the long-term while maintaining the integrity of the forest. (3) For reintroduction purposes, the concept of &lsquo;indicator species&rsquo; is frequently used. These species are often selected based on anecdotal information, rather than scientific rigor. In order to maximize the efficiency of ginseng reintroductions, I analyzed the ability of select putative indicators (herbs, shrubs, and trees) to serve as site and microsite predictors of ginseng growth. Most indicators were ineffective, and the ones that did show a relationship to growth were contra- indicators, predicting reduced individual plant growth. This research may aid reintroduction and agroforestry projects, and thereby reduce the frequency of reintroductions that fail because plants are introduced into suboptimal locations. (4) By experimentally reintroducing two medicinal plants, ginseng and goldenseal, to two sites with three types of disturbance history, I determined that degraded landscapes can return to a forested state that supports medicinal plant growth and reproduction, although microsite and soil conditions were found to be important to consider when reintroducing plants. As such, appropriate future land-management decisions can be made based on land-use legacy. By combining social, economic, and ecological studies, medicinal plant conservation can be implemented through the development of environmental outreach and effective reintroduction strategies.</p>

<p>Blue carbon systems (mangroves, salt marshes, and seagrass beds) sequester large amounts of carbon via primary productivity and sedimentation. Sequestered carbon can be respired back to the atmosphere, buried for long time periods, or exported (&ldquo;outwelled&rdquo;) to adjacent ecosystems. This study estimates the total outwelling of dissolved organic carbon (DOC) from the Neponset Salt Marsh (Boston, Massachusetts) as well as the major plant and sediment processes contributing to the overall flux. The total export was quantified via high-resolution <i> in situ</i> chromophoric dissolved organic matter (CDOM) measurements as a proxy for DOC using 12 years of transect data. Seasonal trends, alternate sources of fresh water, and long-term trends in DOC export will be discussed. To characterize the percentage of this flux attributable to marsh vegetation, the effects of sunlight, anoxia, plant species, biomass type, and microbes on plant leaching were studied using incubations of above- and belowground biomass over four seasons. Seasonal comparisons led to the &ldquo;Fall Dump&rdquo; hypothesis in which higher DOC concentrations are leached during the fall when marsh plants senesce for winter. In summing seasonal fluxes from vegetation, approximately 46% of the total DOC export from the marsh may be attributed to leaching from the three dominant plant species in the Neponset Salt Marsh. The influence of seasonality and climate change (e.g., drought) on both overland flow and deep sediment pore water leaching were also investigated. Depending on season and marsh condition, overland flow and sediment pore water leaching combined could contribute 8&ndash;16% of the total export from the marsh. Finally, the influence of natural sunlight irradiation and microbes on the release of dissolved organic matter (DOM) from resuspended surface sediments was studied and approximately 11&ndash;22% of the total export could be attributable to this flux. Approximately 49 mol C m^&minus;2 yr^&minus;1 are outwelled from the Neponset Salt Marsh and, using net primary productivity estimates from the literature, 16 &plusmn; 12 mol C m^&minus;2 yr^&minus;1 are buried in the Neponset Salt Marsh. </p>

<p> Sediment cores from Cascade Lake (68.38&deg;N, 154.60&deg;W) and Shainin Lake (68.34&deg;N, 151.05&deg;W), Arctic Alaska were selected for paleomagnetic analysis to assess 210Pb-14C age control using paleomagnetic secular variation (PSV) and relative paleointensity (RPI) features, and to quantify environmental magnetic variability during the Holocene and late Pleistocene. U-channels were studied through alternating field (AF) demagnetization of the natural remanent magnetization (NRM), and laboratory-induced magnetizations including anhysteretic remanent magnetization (ARM) acquisition, ARM demagnetization, isothermal remanent magnetization (IRM), and hysteresis experiments to determine magnetic mineralogy and grain-size variability. </p><p> Cascade Lake sediment yields a strong, well-defined characteristic remanent magnetization with average maximum angular deviation values of &lt; 2&deg; and average inclinations within 4&deg; of the expected geocentric axial dipole. Correlation of inclination changes with geomagnetic field models, as well as the Burial Lake record ~ 200 km to the west, indicates a variable offset between the Cascade Lake radiometric chronology and the preferred PSV-derived age model (PSV-1), reaching a maximum offset of 1.5&ndash;2.8 kyr during the mid-Holocene. This offset likely results from either a hard-water effect or the incorporation of watershed-stored terrestrial carbon into ¹⁴C samples. The PSV-1 age model extends the Cascade Lake age model to ~ 21 ka. Cascade Lake sediment may be suitable for RPI estimation using the IRM as a normalizer, however three methods of normalization (magnetic susceptibility (kLF), ARM, and IRM) produce similar normalized remanence results. </p><p> Hysteresis experiments and S-ratios for Cascade Lake glacial till and Shainin Lake sediment supports the hypothesis that local bedrock hosts predominantly high-coercivity magnetic material. However, S-ratios from Cascade Lake (~ 21 ka to present) and Shainin Lake (~ 12.6 ka to present) do not appear consistent with Burial Lake S-ratios, and most S-ratio variability is therefore interpreted as a result of site-specific sedimentation processes and background magnetic assemblages. A Younger-Dryas-aged peak in Shainin Lake S-ratios may be revealed by the increased sensitivity of the S-ratio parameter to magnetite at high-coercivity background levels. Cascade Lake S-ratios increase from 10.3 ka to present, potentially indicating Holocene biogenic magnetite production, down-core magnetic dissolution, or eolian input from a fine-grained, low-coercivity magnetic source that is clearly distinct from eolian magnetite at Burial Lake. Anhysteretic susceptibility (k<p style="font-variant: small-caps">ARM</p>)/k<p style="font-variant: small-caps">LF</p> may be a better indicator of this fine-grained magnetite population observed in the north-central Brooks Range, however the origin of this magnetic component remains unclear. This research highlights the potential advantages of supplementing ¹⁴C dating with additional dating methods, and will benefit from ongoing efforts to improve age control (e.g., cryptotephra exploration) and additional magnetic experiments to constrain the source of fine-grained magnetite.</p>

Contaminated fomites are a cause of concern for the spread of health care-associated infections (HAI's). Previous research has placed emphasis on fomites in patient rooms and patient bathrooms with limited focus on the spread of microorganisms on fomites in non-patient care areas. The present study monitored surrogate virus tracer (MS2 coliphage) spread from public restrooms (used by staff and visitors) to waiting areas in a surgical ward in a Level I Trauma Center. The coliphage (virus) MS2 was added onto the entrance door handle of male and female public restrooms. Four hours later, various surfaces in the restroom and waiting area were sampled. Sampling periods were conducted in duplicate consisting of before cleaning, cleaning with the current cleaning product and procedure and cleaning with an intervention (inclusion of a bleach based disinfectant wipe) in addition to the current cleaning product and procedures. Before cleaning took place, the virus tracer was detected on all 21 of the sites sampled in the restrooms and 5/9 sites within the hallway ranging from 15-50 feet from the restroom. These results indicated that a virus could spread from public restrooms to other sites in the restroom and to locations in the surgical ward. The addition of a bleach based disinfectant wipe reduced the virus by another 90% compared to current disinfecting and cleaning procedures. Coliphage MS2 has been used as a model virus for norovirus and rhinovirus since they exhibit similar survival on fomites and resistance to disinfectants. The data generated can be used in quantitative microbial risk assessment models to assess the risk of pathogens spreading from restrooms to patient waiting areas and patient care areas in healthcare settings. Based on this study, facilities should consider broadening their cleaning and disinfection protocols to include both patient care and non-patient care areas.

<p> Biological soil crusts are communities of bacteria, microfungi, algae, lichens, and/or bryophytes that colonize the surfaces of soils where other vegetation is sparse. Soil crust communities are best known from the world&rsquo;s arid and semiarid regions, including North America&rsquo;s hot and cool deserts, where they aid in soil stabilization and aggregation, reduce erosion, and contribute to nutrient inputs in the soil. Although a significant body of work has emerged on soil crust function in arid and semiarid environments, there is still much to be learned about their geographical distributions within and across different vegetation communities. Sagebrush shrublands and pinyon-juniper woodlands are common communities in the central Great Basin, but this region is under-studied with respect to biological crust composition and distribution. I collected data on soil pH and the cover of plant functional groups and biological soil crusts in sagebrush and pinyon-juniper zones in the Wassuk Range of western Nevada. Regression models revealed that in the shrublands, soil crusts associate negatively to rock cover and positively to moderately dense shrub canopy. In the woodlands, ground-cover of rocks and woody litter have a negative association with soil crusts. Sagebrush and pinyon-juniper communities are facing many stressors and undergoing changes in structure. My results offer a possible starting point for assessing how the biological crusts in these habitats might respond to these changes based on their current distributional controls. Future research should further explore the response of biological crusts to trajectories of change in the central Great Basin ecoregion.</p>