An acoustic frequency-swept wave was investigated as a means for determining Snow Water Equivalent (SWE) in cold wind-swept prairie and sub-alpine environments. Building on previous research conducted by investigators who have examined the propagation of sound in snow, digital signal processing was used to determine acoustic pressure wave reflection coefficients at the interfaces between 'layers' indicative of changes in acoustic impedance. Using an iterative approach involving boundary conditions at the interfaces, the depth-integrated SWE was determined using the Berryman equation from porous media physics. Apparatuses used to send and receive sound waves were designed and deployed during the winter season at field sites situated near the city of Saskatoon, Saskatchewan, and in Yoho National Park, British Columbia. Data collected by gravimetric sampling was used as comparison for the SWE values determined by acoustic sounding. The results are encouraging and suggest that this procedure is similar in accuracy to SWE data collected using gravimetric sampling. Further research is required to determine the applicability of this technique for snow situated at other geographic locations.

Hydrological models have been developed to estimate snow accumulation, snowmelt and snowmelt runoff on the Canadian Prairies; however, their proper scale of application is unknown in the Prairie environment. The first objective of this thesis is to examine the proper scale for pre-melt snow accumulation as snow water equivalent (SWE) and snowmelt in a Prairie first order basin. Spatially distributed and spatially aggregated approaches were used to calculate SWE and snowmelt at St. Denis National Wildlife Area (SDNWA). Both approaches used models with similar physics, but differed in the model scale at which calculations were carried out. The simulated pre-melt SWE, cumulative seasonal SWE, and daily snowmelt from the two modelling approaches were compared to field observations of pre-melt SWE, cumulative seasonal SWE, and daily snowmelt; comparisons of areal cumulative seasonal SWE, areal snowmelt, snowmelt duration, and snow-covered area were also conducted between two modelling approaches. Results from these comparisons showed that both approaches had reasonable and similar accuracy in estimation of SWE and snowmelt. The spatially aggregated approach was more computationally efficient and was selected as a modelling scale for small-sized prairie basins. <p>Another objective of this thesis is to derive a snow hydrology model for the Canadian Prairies. Physically-based hydrological models were assembled in the Cold Regions Hydrological Model Platform (CRHM) using the aggregated approach. Tests of pre-melt SWE and surface snowmelt runoff were conducted at two basins in Saskatchewan Creighton Tributary of Bad Lake and Wetland 109, St. Denis. Results showed that the snow hydrology model had a reasonable capability to simulate SWE and snowmelt runoff to the stream and wetland. <p>Droughts are natural hazards that develop frequently on the Canadian Prairies. Analyzing the impact of drought on hydrological processes and water supply is another objective of this thesis. Synthetic drought scenarios were proposed for the Creighton Tributary of Bad Lake and the corresponding impacts on the snowmelt runoff-related processes were examined. Results indicated that wind redistribution of snow was very sensitive to drought conditions, sublimation of blowing snow and snow-covered period were sensitive to drought, but winter evaporation and infiltration did not show strong trend. The results also showed that drought conditions had magnified effects on the snowmelt runoff and could cause cessation of streamflow. Also, the impacts of the recent 1999-2005 drought on the snowmelt hydrology were investigated at St. Denis. Results illustrated that three-years (1999-2002) of severe winter drought were followed by a normal year (2002-03) and then a two-year (2003-05) recovery period, and then returning to normal (2005-06). Results showed that both snowfall and rainfall during hydrological winter were consistently low for severe drought and surface snowmelt runoff was very much lower during severe drought, about 45-65 mm less compared to that in the normal periods.

The overall objective of my thesis research was to develop methodologies for assessing effects of mining effluents on pristine and sensitive northern rivers. I used a multi-trophic level approach in field studies to evaluate current monitoring methods and to determine whether metal mining activities had affected two otherwise pristine rivers that flow into the South Nahanni River, NWT; a World Heritage Site. Upstream reference conditions in the rivers were compared to sites downstream and further downstream of mines. The endpoints evaluated included concentrations of metals in river water, sediments and liver and flesh of slimy sculpin (Cottus cognatus); benthic algal and macroinvertebrate abundance, richness, diversity, and community composition; and various slimy sculpin measures. Elevated concentrations of copper (p=0.002)and iron (p=0.001) in liver tissue of sculpin from the Flat River were associated with high concentrations of mine-derived iron in river water and copper in sediments that were above national guidelines. In addition, sites downstream of the mine on the Flat River had increased algal abundances (p=0.002) and altered benthic macroinvertebrate communities ((p<0.001) whereas the sites downstream of the mine on Prairie Creek had increased benthic macroinvertebrate taxa richness (p=0.050) and improved sculpin condition (males: p=0.008; females: p=0.001). Biological differences in both rivers were consistent with mild enrichment of the rivers downstream of current and historical mining activity. Although the effects of mining activities on riverine biota in these northern rivers are currently limited, results of this research show that there is potential for effects to occur with proposed growth in mining activities.<p> Laboratory exposures were conducted using slimy sculpin, identified as a sentinel fish species in pristine northern rivers, to identify alternative methods for assessing toxicity of contaminants of concern in mining effluents. Ammonia was selected for the exposures based on effluent characteristics of northern mining effluents. Ammonia is known to be an important toxicant in aquatic environments. Although ammonia toxicity has been well studied in many fish species, effects of chronic exposure of slimy sculpin, a critical biomonitoring species for northern aquatic habitats, are not well known. Slimy sculpin were exposed to six concentrations of un-ionized ammonia relevant to concentrations found in northern mining effluents: control (0 ppm), 0.278 ppm, 0.556 ppm, 0.834 ppm, 1.112 ppm, and 1.668 ppm. An LC50 of 1.529 ppm was calculated from mortality data. Histopathological examination of gills indicated significant tissue damage, measured as lamellar fusion and epithelial lifting, at 0.834, 1.112, and 1.668 ppm. Using gill endpoints, NOEC and LOEC were calculated as 0.556 ppm and 0.834 ppm respectively. An EC50 of 0.775 ppm was determined for lamellar fusion and an EC50 of 0.842 ppm for epithelial lifting. Hemorrhage of gills was present in mortalities which occurred at 1.668 ppm of un-ionized ammonia. A significant decrease in liver somatic index (LSI) was seen in both male and female fish at 0.834 and 1.112 ppm, respectively. Gonadosomatic index (GSI) in female fish significantly increased at 1.668 ppm un-ionized ammonia with an associated significant increase in total whole body testosterone concentrations. GSI in male fish also significantly increased at 1.668 ppm but no differences were seen in testosterone concentrations. No significant differences were seen in gonad histopathological assessments or condition factor. Results from this study indicate that ammonia concentrations commonly reported in northern mine effluents hold potential to affect the health of slimy sculpin including acute, chronic, histological and endocrine endpoints. <p> Results from both the field study and laboratory exposures provide direction for future monitoring programs in pristine northern rivers and emphasize the importance of monitoring tools to detect change in these ecosystems. I recommend that monitoring of northern pristine rivers focus on a multi-trophic monitoring approach including indicators in algal and benthic macroinvertebrate communities due to their responsiveness. Laboratory exposures using slimy sculpin should be considered to obtain toxicological information for northern contaminants of concern. Gill histopathology endpoints may be a more sensitive indicator for detecting effects in slimy sculpin exposed to ammonia than traditional chronic endpoints. I also recommend monitoring of metal burdens in periphyton and benthic invertebrates for assessment of exposure to mine effluent and causal association in areas of low fish abundance.

Depressions in the prairie pothole region (PPR) are commonly referred to as sloughs and were formed during the most recent glacial retreat, ~10-17 kyrs ago. They are hydrologically isolated, as they are not permanently connected by surface inflow or outflow channels. Extreme thunderstorms are common across the prairies and the hydrologic response of isolated wetlands to intense rainfall events is poorly understood. The purpose of this study was to compare the response of different landscape/ecological elements of a prairie wetland to snowmelt and extreme rainstorms. Comparisons were completed by investigating the spring snowmelts of 2005 and 2006 and the rainstorm event of June 17 - 18, 2005, in which 103 mm fell at the St. Denis National Wildlife Area (NWA) Saskatchewan, Canada (106°06'W, 52°02'N). The wetland was separated into five landscape positions, the pond center (PC), grassed edge (GE), tree ring (TR), convex upland (CXU), and concave upland (CVU). Comparison of the rainfall of June 17 18, 2005 with the spring snowmelts of 2005 and 2006 indicates that the hydrologic consequences of these different events are similar. Overland flow, substantial ponding in lowlands, and recharge of the groundwater occur in both cases. Analysis of this intense rainfall has provided evidence that common, intense rainstorms are hydrologically equivalent to the annual spring snowmelt, the major source of water for closed catchments in the PPR.

The Prairie Pothole Region (PPR) of North American contains millions of wetlands in shallow depressions that provide important hydrological and ecological functions. To assess and model these functions it is important to have accurate methods to quantify wetland water volume storage. Hayashi and van der Kamp (2000) developed equations suitable for calculating water volume in natural, regularly shaped wetlands when two coefficients are known. This thesis tested the robustness of their full and simplified volume (V) area (A) depth (h) methods to accurately estimate volume for the range of wetland shapes occurring across the PPR. Further, a digital elevation model (DEM) derived from light detection and ranging (LiDAR) data was used to extract the necessary data for applying the simplified V-A-h method at a broad spatial scale. Detailed topographic data were collected for 27 wetlands in the Smith Creek Research Basin and St. Denis National Wildlife Area, Saskatchewan that ranged in surface area shape. The full V-A-h method was found to accurately estimate volume (errors <5%) across wetlands of various shapes and is therefore suitable for calculating water storage in the variety of wetland shapes found in the PPR. Analysis of the simplified V-A-h method showed that the depression (p) and size (s) coefficients are sensitive to the timing of area and depth measurements and the accuracy of area measurements. Surface area and depth should be measured concurrently at two points in time to achieve volume errors <10%. For most wetlands this means measuring area and depth in spring when water levels are approximately 70% of hmax, and also in late summer prior to water depths dropping below 0.1 m. The wetted perimeter of the deepest water level must also be measured accurately to have volume errors less than 10%. Applying the simplified V-A-h method to a LiDAR DEM required GIS analysis to extract elevation contours that represent potential water surfaces. From these data the total wetland depth and s coefficient were estimated. Volume estimates through this LiDAR V-A-h method outperformed estimates from two volume-area equations commonly used in the PPR. Furthermore, the process to extract the wetland coefficients from the LiDAR DEM was automated such that storage could be estimated for the entire St. Denis National Wildlife Area. Applying the simplified V-A-h method according to the guidelines and data sources recommended here will allow for more accurate, time-effective water storage estimates at multiple spatial scales, thereby facilitating evaluation and modelling of hydrological and ecological functions.

The intensification of land-water management due to agriculture, forestry, and urbanization is a global phenomenon increasing the pressure on worlds water resources and threatening water security in North America. The Prairie Pothole Region of North America covers approximately 775,000 km2 and contains millions of wetlands that serve important hydrological and ecological functions. The unique hummocky topography and the variable effect of different processes contribute to high spatio-temporal variability in soil water, posing major challenges in hydrological studies. The objectives of this study were to a) examine the spatial pattern of soil water storage and its scale and location characteristics; and b) to identify its controls at multiple scales. Soil water content at 20 cm intervals down to 140 cm was measured along a transect extending over several knolldepression cycles in a hummocky landscape. High water storage in depressions and low water storage on the knolls created a spatial pattern that was inversely related to elevation. Spatial patterns were strongly similar within any given season (intra-season rank correlation coefficient as high as 0.99), moreso than between the same season over different years (inter-annual rank correlation coefficient as high as 0.97). Less similar spatial patterns were observed between different seasons (inter-season rank correlation coefficients as high as 0.90). While the intra-season and inter-annual spatial patterns were similar at scales >18 m, the inter-season spatial patterns were similar at much large scales (>72 m). This may be due to the variations in landform elements and micro-topography. The similarity at scales >72 m were present at any time and depth. However, small- and medium-scale spatial patterns changed with depth and with season due to a change in the hydrological processes. The relative dominance of a given set of processes operating both within a season and for the same season over different years yielded strong intra-season and inter-annual similarity at scales >18 m. Moreover, similarity was stronger with increasing depth, and was thought to be due to the dampening effect of overlying soil layers that are more dynamic. Similarity of spatial patterns over time helps to identify the location that best represents the field averaged soil water and improves sampling efficiency. Change in the similarity of scales of spatial pattern helps identify the change in sampling domain as controlled by hydrological processes. The scale information can be used to improve prediction for use in environmental management and modeling of different surface and subsurface hydrological processes. The similarity of spatial pattern between the surface and subsurface layers help make inferences on deep layer hydrological processes as well as groundwater dynamics from surface water measurements.

Snake populations in the North American tallgrass prairie appear to be declining, yet data unavailability impedes the development of enhanced ecological understanding of snake species-habitat relationships and also hinders snake conservation efforts. This study addresses both issues for the snakes of Illinois in two steps. In a two-year mark-recapture study at twenty-two sites within six northern Illinois prairie preserves, I investigated snake species-habitat relationships using habitat variables at three scales: microhabitat (< 100 m), landscape (1 - 10 km), and regional (> 10 km). A total of 120 snakes representing seven species was captured using drift fence arrays associated with funnel traps and sheet metal cover. The low numbers and diversity of snakes captured, when compared to historic evidence, indicate that Illinois snake populations have declined. At the microhabitat scale, non-metric multidimensional scaling and Mantel tests revealed a relationship between snake species composition and elevation. At the landscape-scale, snake species composition varied along an agricultural-urban cover gradient. Classification and regression trees and maximum entropy models (Maxent) were used to identify the scales at which snake species-habitat relationships were strongest. Six of seven regression trees for individual snakes species contained habitat variables at the landscape scale. Important landscape characteristics included patch size, isolation, and land cover, metrics that strongly covary with habitat loss. Microhabitat features only appeared in the regression trees of two species and in three Maxent models. This study indicates that habitat loss has shaped the current distribution of snake species in Illinois's remnant prairies and that snake conservation efforts should emphasize the landscape-scale. Finally, I developed a risk ranking system based on natural and life history characteristics to assess the conservation status of Illinois's 38 snake species. Cluster analysis identified eight groups of snakes, similar in terms of risk factors, with high risk species sharing characteristics such as large body size, long life span, limited habitat breadth, and a high anthropogenic threat ranking. Here, I emphasize the need for basic demographic studies on snakes and suggest that ranking systems be used with population data (when available) and expert opinion to identify snake species of conservation concern in other regions. / Dissertation

Cultivation and drainage projects associated with livestock production have substantially disturbed resaca wetlands and wet prairie habitats in southern Texas. As a consequence of the anthropogenic disturbances, the area of these wetlands has been reduced and the ecological integrity of the remaining wetlands has been compromised. The goal of this study was to explore effective strategies for ecological restoration of coastal prairie and resaca ecosystems in south Texas and provide restoration recommendations to the National Park Service at Palo Alto Battlefield National Historic Site (NHS). Field experiments were conducted to evaluate the effectiveness of different approaches for restoring Spartina spartinae on disturbed saline flats. A resaca hydrologic study was initiated to evaluate the groundwater hydrology in disturbed versus undisturbed resaca wetlands and explore potential restoration strategies. Transplanting S. spartinae in the fall season was more successful (80% survivability) than seeding (0% initial establishment), spring transplanting (0% survival), spring and fall mechanical transplanting (0% and 6% survivability, respectively). Soil disturbance significantly affected (p < 0.05) survival of transplanted tillers and basal diameter of both the bare root and container-grown transplants in the fall manual treatments. The initial hydrologic study of the resaca wetlands found that vegetation rooting zone hydrology was likely dependent on surface water rather than groundwater. These findings suggest that strategies that restore surface hydrologic regimes will likely restore the ecosystem structure and function of disturbed resacas. Manually transplanting bare-root stock of S. spartinae in the late fall season without soil disturbance will increase the likelihood of successful saline flat restoration.

L'objectif de cette étude a été d'évaluer la productivité et la valeur nutritive de 13 espèces de graminées natives, issues de prairies permanentes de fertilité moyenne, et de comprendre les bases fonctionnelles de ces processus grâce à la mesure de traits fonctionnels aériens. Ces espèces ont été cultivées en culture pure dans un dispositif factoriel complet, croisant deux facteurs de gestion : la fréquence de coupe (3 ou 6 coupes par an) et le niveau de fertilisation azotée (120 et 360 kg N ha-1 an-1). Nous montrons que des syndromes distincts de traits d'effet déterminent la productivité et la valeur nutritive. Les différences de nutrition azotée (indice de nutrition et efficience d'utilisation de l'azote) entre espèces affectent la productivité aérienne. Deux traits (teneur en azote et teneur en matière sèche des limbes) se démarquent comme indicateurs de la productivité et de la valeur nutritive des espèces étudiées. Celles ci ont été classées en quatre groupes selon la valeur de leurs traits. Une augmentation de la fréquence de coupe a modifié des traits foliaires entraînant une baisse de digestibilité des limbes, ce qui a été interprété comme une stratégie d'évitement du pâturage. Une réduction de l'apport d'azote a entraîné une augmentation de la teneur en matière sèche et de la durée de vie des feuilles, ce qui a été interprété comme une stratégie de conservation des nutriments. Les espèces issues d'habitats plus perturbés présentaient des valeurs de traits qui tendaient à réduire leur digestibilité. Nos résultats soulignent la diversité fonctionnelle élevée des graminées prairiales, diversité qui contribue à la coexistence de ces espèces dans la prairie permanente et favorise la stabilité de la production et de la valeur nutritive dans cet écosystème.

Project (D. Min.)--Perkins School of Theology, Southern Methodist University, 1989. / Includes bibliographical references (leaves 128-129).