The Arizona Nature Conservancy's Hassayampa River Preserve is 50 miles northwest of Phoenix near the town of Wickenburg. Four miles of the largely ephemeral Hassayampa River are perennial within the preserve, supporting one of the finest remaining cottonwood-willow forests in the state. Stream flows are affected by wells pumping ground water directly from the alluvial aquifer and may be influenced by wells which intercept lateral inflow from the regional basin-fill aquifer. Developing effective management strategies to protect base flow conditions (∼4 cfs) depends on a clear understanding of the surface and ground-water systems in the preserve. Provided that ground water developers near Wickenburg recognize and incorporate the interconnected nature of each hydrologic system, perennial flow within the preserve is not believed to be immediately threatened. (Abstract shortened with permission of author.)

Thesis (M.S.)--Bowling Green State University, 2005. / Document formatted into pages; contains xii, 106 p. : ill., maps. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 100-104). Also available on the World Wide Web.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 26-30). Also available via Humboldt Digital Scholar.

Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

The global community is struggling with mitigating the effects of widespread habitat loss and degradation; the effects of which are being further magnified in the face of global climate change. Quality natural habitat is becoming increasingly limited and atmospheric carbon levels continue to rise. Therefore, land managers responsible for multiuse management are often faced with the dilemma of managing ecosystems for biodiversity, as well as optimizing ecosystem services such as carbon storage and sequestration. However, some management techniques used to meet these objectives may yield conflicting results, specifically, the management tool of prescribed fire. Fire is crucial in maintaining species composition and structure in many ecosystems, but also results in high carbon emissions. Thus, it is important for land mangers to achieve the most efficient prescribed fire management regime to both preserve plant and animal communities, and optimize carbon storage. A former ranchland at the Disney Wilderness Preserve, Central Florida, USA is being restored to native ecosystems and managed to preserve biodiversity and increase carbon storage. This study quantified the carbon stocks within the aboveground biomass, litter, and top 90 cm of soil in five ecosystems at the Disney Wilderness Preserve, all of which are managed with prescribed fire every two to three years. These carbon stocks were compared in ecosystems in different stages of restoration: bahia grass pasture, pasture in restoration for longleaf pine flatwoods, and restored longleaf pine flatwoods. The carbon stocks were also compared among three restored flatwoods communities: longleaf pine flatwoods, slash pine flatwoods, and scrubby flatwoods. To determine the effects of the current prescribed fire management, carbon stocks were quantified and compared in recently burned areas (burned 4 months prior) and areas burned two to three years prior, in all ecosystems. Soil carbon properties were assessed using ¹³C isotope analysis. Aboveground biomass and litter carbon stocks were found to increase with higher stage of restoration, and were significantly less in areas with recent fire management. The results of this study did not provide evidence that soil carbon stock was significantly different in different stages of restoration or at different times since fire, but soil carbon stock was found to be significantly different among the flatwoods communities. In un-restored pasture and pasture in restoration sites, the soil was found to be increasingly depleted in ¹³C with increasing soil depth. This pattern indicated that carbon in the upper, more labile soil carbon pool had been derived from current C4 pasture or native grasses, while carbon in the deeper, more stable carbon pool is a legacy of the historical C3 forest vegetation that existed prior to conversion to pasture. Additionally, a pattern of less depletion in ¹³C with increasing time since deforestation was noted, indicating an increasing loss of historic forest carbon with increasing pasture age. As the pastures in restoration for longleaf pine flatwoods mature, the isotopic composition of the soil profile in the restored longleaf pine flatwoods may serve as a reference value for the soil profiles of these sites. Overall, the mean carbon stock in the aboveground biomass, litter and top 90 cm of soil in the un-restored pasture was ~13.3 kg C/m², the carbon stock in the pasture in restoration was ~12.7 kg C/m², the longleaf pine flatwoods had the highest carbon stock at ~17.7 kg C/m², the scrubby flatwoods had the smallest carbon stock at ~7.7 kg C/m², and the slash pine flatwoods had a carbon stock of ~15.8 kg C/m².

The designers of architecture in our national and state parks appear remarkably unenlightened in a day when the design of nearly all our structures is being given a careful re-analysis of function and purpose. Indeed, these designers go to great lengths to avoid admitting that any progress has been made in the building profession in the past 300 years. This thesis is an attempt to refute the current dominant philosophy of national park architecture, and to present a possible new approach to the problem. The building designs included here, for an actual site in the Adirondack mountains of New York, are intended to illustrate the tenet of contemporary structures for the needs of contemporary man. / Master of Science

No description available.

The purpose of this study was to compare vegetation systems among three artificially isolated wetlands on the west end of Galveston Island. Sample sites were identified as isolated wetlands and anthropogenic impact was observed. Wetland plant communities were identified through representative field studies using a modified quadrat method. Species composition, species diversity, evenness, cover and frequency were compared among the three sample sites. Salinity at all three sample sites remained at 0 ppt through June, July and August. Salinity increased to 10 ppt in both Lafitte’s Cove Nature Preserve and Dos Vacas Muertas Bird Sanctuary in September. No change in salinity was recorded at Isla Del Sol. At Lafitte’s Cove Nature Preserve the majority of the soil composition included Mustang-Nass. Dos Vacas Muertas Bird Sanctuary consisted of a Mustang fine sand complex while Isla Del Sol consisted of Mustang fine sand and Nass very fine sandy loam. Sampling at Lafitte’s Cove Nature Preserve produced 15 species. Dos Vacas Muertas Bird Sanctuary added 7 new species while Isla Del sol added 6 new species for a total of 28 species within the three sites. The overall plant species’ richness of Lafitte’s Cove Nature Preserve and Dos Vacas Muertas Bird Sanctuary remained low. A high frequency was observed in Sesbania drummondii and Cyperus odoratus at Lafitte’s Cove Nature Preserve. Sesbania drummondii retained the highest percent cover for the site. At Dos Vacas Muertas Bird Sanctuary, Phragmites australis and Spartina patens demonstrated a high frequency as well as percent cover. Frequency was highest in Juncus roemerianus and Eleocharis geniculata at Isla Del Sol. Several plant species exhibited a high frequency while overall frequency was more evenly distributed in Isla Del Sol than the other sample sites. Percent cover was highest in Juncus roemerianus and Borrichia frutescens. Isla Del Sol had the highest species diversity and evenness of all three sample sites. Similarity in species composition was high with the coefficient for pair-wise comparisons in Isla Del Sol and Lafitte’s Cove Nature Preserve being the highest. The three sample sites shared 53% to 73% of their species. Isla Del Sol possessed 6 species that were absent from the other sample sites. Dos Vacas Muertas Bird Sanctuary contained 4 unique species while Lafitte’s Cove Nature Preserve had only 3 unique species. Dos Vacas Muertas Bird Sanctuary had the lowest index score at 10. Lafitte’s Cove Nature Preserve had the highest index score at 24 while Isla Del Sol followed close behind at 22. For the Anthropogenic Activity Index, Lafitte’s Cove Nature Preserve still retained the highest score at 14. Results for Isla Del Sol showed an index score of 13 while Dos Vacas Muertas Bird Sanctuary scored only 7. The results of this study show that although Dos Vacas Muertas Bird Sanctuary had lower levels of disturbance when compared to the other sample sites, it still experienced a lower species diversity. Isla Del Sol had the highest species diversity and evenness of the sites. Lafitte’s Cove Nature Preserve had the highest level of disturbance and maintained a low level of diversity as well. When comparing the results to historical data, a reduction in salt marsh plant species was observed. Species that are often associated with freshwater to brackish marsh wetlands have become more dominant in the sample sites.

River-groundwater exchange (hyporheic exchange) influences temperature, water chemistry, and ecology within rivers and alluvial aquifers. Rates and patterns of hyporheic exchange depend on riverbed permeability, pressure gradients created by current-obstacle interactions, and river stage fluctuations. I demonstrate the response of hyporheic exchange to three examples of these driving forces: fine-scale permeability structure in cross-bedded sediment, current interactions with large woody debris (LWD), and anthropogenic river stage fluctuations downstream of dams. Using numerical simulations, I show that cross-bedded permeability structure increases hyporheic path lengths and modifies solute residence times in bedforms. The tails of residence time distributions conform to a power law in both cross-bedded and internally homogeneous riverbed sediment. Current-bedform interactions are responsible for the decade-scale tails, rather than permeability heterogeneity. Like bedforms, wood debris interacts with currents and drives hyporheic exchange. Laboratory flume experiments and numerical simulations demonstrate that the amplitude of the pressure wave (and thus hyporheic exchange) due to a channel-spanning log increases with channel Froude number and blockage ratio (log diameter : flow depth). Upstream from LWD, downwelling water transports the river’s diel thermal signal deep into the sediment. Downstream, upwelling water forms a wedge of buffered temperatures. Hyporheic exchange associated with LWD does not significantly impact diel surface water temperatures. I tested these fluid and heat flow relationships in a second-order stream in Valles Caldera National Preserve (NM). Log additions created alternating zones of upwelling and downwelling in a reach that was previously losing throughout. By clearing LWD from channels, humans have reduced hydrologic connectivity at the meter-scale and contributed to degradation of benthic and hyporheic habitats. Dams also significantly alter hydrologic connectivity in modern rivers. Continuous water table measurements show that 15 km downstream of the Longhorn dam (Austin, Texas), river stage fluctuations of almost 1 m induce a large, unsteady hyporheic exchange zone within the bank. Dam-induced hyporheic exchange may impact thermal and geochemical budgets for regulated rivers. Together, these three case studies broaden our understanding of complex drivers of hyporheic exchange in small, natural streams as well as large, regulated rivers. / text