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Based upon research in the state of Himachal Pradesh in the Western Himalaya of north India, this dissertation examines ways various people know, have access to and use forest resources. It examines knowledges which are privileged and those less so, and accompanying expressions of power in negotiating access to those resources. Here knowledge is seen as inextricably tied to maneuverable, situationally contingent enunciations of power. If exercises of power are understood as related to people's interpretations of the parameters of the "positions"--both social and geographical--that they operate within, then categories such as government official or villager, tribal or nontribal, women or men, townsfolk or forest communities, high caste or low are not seen as unified or fixed ones in terms of interpretations of or access to power. Since some institutionally defined positions are perceived as imbued with more or less inherent power, this combination of institutional as well as individual notions of power is examined as these relate to differently valued knowledges about forest resources. These shifting ideas about and expressions of power are additionally affected by literal movement across landscapes. Areas traversed, distances covered, length of time in a region and the appropriateness of such motion to particular positions all contribute to the valuation of different knowledges. Positionality and related knowledges are tracked through this literal as well as figurative movement, reflecting varying degrees of "room to move" through various social and physical realms for particular individuals. Methodological approaches include: participant observation, semi-structured interviews, cultivated and noncultivated plant matrices, plant list testing, map comparisons, discourse analysis of historical and contemporary documents, and travel and investigative questioning within the broader area of the Western Himalaya for regional contextualization. The dissertation shows that forest-related activities are directed by specific knowledges, and related notions of importance or value of those knowledges. The valuing of state knowledges over local use-knowledges prevents productive cooperation between various groups on forest related projects. The sometimes contradictory expressions of knowledge and exercises of power are a result of people responding to various inconsistencies in their lives related to the availability of forest resources. Corruption and subversion are two responses to such contradictions. Problems of diminishing forest resources, and limited access to them, must be, it is concluded, situated within these fields and relations of power.

<p> The population and industrial complexes of Choctaw County obtains much of its water from an aquifer system in the Tertiary age Wilcox unit of the Mississippi Embayment. Utilizing 20 years of physical chemistry (P-Chem) analysis, potentiometric groundwater records of Choctaw County public water wells as well as industrial P-Chem analysis and surface and ground water level records from an industrial complex, this study examined the changes to the hydrosphere that has taken place since 1995. Analysis of the hydrosphere shows that over the last 20 years, there has been a drop in the potentiometric surface of the Wilcox aquifer system. The analysis also shows changes in the P-Chem of the hydrosphere, changes such as a decrease in the concentration of free CO2 and chloride, and fluctuations of Alkalinity. Comparisons between groundwater records taken from the industrial complex and other locations around Choctaw County, show little variation in the physical chemistry.</p>

<p> Groundwater is an essential input to agriculture world-wide, but it is clear that current rates of groundwater use are unsustainable in the long term. This dissertation assesses both current use of groundwater for country- to global-scale agriculture, and looks at the future of groundwater. The focus is on 1) quantifying food directly produced as a result of groundwater use across spatially-varying agricultural systems, 2) projecting future groundwater demands with consideration of climate change and human decision-making, and 3) understanding the system dynamics of groundwater re-use through surface water systems. All three are addressed using a process-based model designed to simulate both natural and human-impacted water systems. </p><p> Irrigation can significantly increase crop production. Chapter 1 combines a hydrology model (WBM) with a crop model to quantify current crop production that is directly attributed to groundwater irrigation in China. Unsustainably-sourced groundwater &mdash; defined as groundwater extracted in excess of recharge &mdash; accounted for a quarter of China&rsquo;s crop production, and had significant spatial variability. Climate variability and groundwater demand magnified one another in hot and dry years, causing increased irrigation demand at the same time as limited surface water supplies. </p><p> Human decisions about water resource management can impact both the demand and sustainability of groundwater use. Chapter 2 takes an interdisciplinary approach to projecting India&rsquo;s future (to 2050) groundwater demands, combining hydrology and econometric modeling. The econometric model projects how humans make decisions to expand or contract the irrigated land area of crops in response to climate change. Even in areas with precipitation increases, human decisions to expand irrigated areas led to increasing demands for groundwater. We additionally assessed the potential impact of a large water infrastructure project to alleviate groundwater demands in India, and found that maximum alleviation (up to 16%) was dependent upon the storage volume and location of new reservoirs. </p><p> One proposed method for reducing the world&rsquo;s demand for groundwater is to increase the efficiency of agricultural water use. However, these same inefficiencies cause a portion of extracted groundwater to enter surface water systems; it can then be reused, creating a complex system in which groundwater demand does not linearly decline with increased water use efficiency. Chapter 3 quantifies the amount of groundwater that enters surface water systems, the number of times this water is reused for agriculture, and the minimum amount of groundwater required by current agricultural systems in the hypothetical scenario of perfect irrigation efficiency.</p>

<p> Each fall hunters kill hundreds of thousands of White-tailed Deer (<i> Odocoileus virginianus</i>) in Missouri and Illinois. Field dressing these deer provides a large influx of nutrient rich offal into the ecosystem. To date, little research has examined the effects of this resource on wildlife. We used trail cameras positioned over offal piles to examine species richness and diversity in a range of habitats during the 2011-2013 hunting seasons in Missouri and Illinois. There were a total of 17 different sampling sites, resulting in over 4 thousand photographs. Images were analyzed and organized into timed feeding events. Sites were categorized into one of three habitat types: field, edge, or forest. We documented 10 different scavenger species feeding on the offal. There was no significant difference in scavenger diversity (<i>F</i>=2.95; <i>d.f.</i>= 2,14; <i> p</i>=0.085), richness (<i>F</i>=2.25; <i>d.f.</i>2, 14; <i>p</i>=0.14;), nor habitat preference (<i>F</i>=0.51; <i> d.f.</i>2,14; <i>p</i>= 0.61) among habitat types. We also found no significant difference in the community structure of scavengers among the three habitat types (<i>R</i>= -0.049; <i>p</i>=0.64). However, there was a difference in the preferred mean feeding times of avian vs. mammalian scavengers (<i>U</i>=1,215.5; <i>Z</i>=11.24; <i> p</i>=0). The presence of offal piles does not appear to repel deer, as they were frequently observed in close proximity. The apparent similarity of the scavenger guild among habitat types can be attributable to the mosaic of fragmented habitat that characterizes the Midwest, as well as the generalized behavior of the species.</p>

<p> The goal of this study is to characterize spatial variability of snow water equivalent (SWE) at the meter scale. The study includes measurement of SWE with a new pressure sensor and use of meteorological sensor data to investigate physical properties within the snowpack that can affect sensor measurement. The new sensor, which can continuously measure a load equivalent to up to 5.5 meters of snow, is designed to be smaller and less expensive (&lt; $1,500) than traditional pressure sensors (> $10,000). Manual snow cores and detailed snow pit analyses were performed to assess accuracy of the sensors and identify physical properties that may be related to sensor measurement error. SWE sensor response and accuracy were assessed between sensors and through comparison with bulk precipitation gage, manual SWE measurements, and snow pillows. SWE sensor readings compared favorably to other measurement methods, particularly in early and peak season. Spatial variability of SWE during the melt season of the two low-snow years during the study period confounded our ability to compare multiple sensor readings for validation. Spatial variability of SWE at study sites was calculated from sets of manual SWE measurements. The correlation length of 80 cm, determined using semi-variograms, highlights the small scale variability in SWE. Statistical resampling of manual measurements suggests that a minimum of ten manual measurements are needed to get within 10% of the spatial average of SWE. Although SWE can remain relatively stable during the melt period, this can be a result of increased density with decreasing snow depth, suggesting that simple inferences about SWE from depth measurements are not appropriate.</p>

<p>The majority of the current production, use, and disposal of engineered nanomaterials (ENMs) occur in terrestrial environments, and consequently terrestrial ecosystems are and will increasingly be some of the largest receptors of ENMs at all stages of their life cycles. In particular, soil is predicted to be one of the major receptors of ENMs due to ENM-contaminated biosolid fertilizer and nanopesticide application to agricultural fields, runoff from landfills or ENM-bearing paints, or atmospheric deposition. Both agricultural and natural systems are at risk to ENM contamination via these release scenarios, which makes it necessary to understand the interactions between ENMs, soils, and soil organisms such as plants in order to predict their impacts in real-world scenarios. Gravity-driven vertical transport of TiO2, CeO2, and Cu(OH)2 engineered nanomaterials (ENMs) and their effects on soil pH and nutrient release were measured in three unsaturated soils. ENM transport was found to be highly limited in natural soils collected from farmland and grasslands, with the majority of particles being retained in the upper 0-3 cm of the soil profile, while greater transport depth was seen in a commercial potting soil. Physical straining appeared to be the primary mechanism of retention in natural soils as ENMs immediately formed micron-scale aggregates, which was exacerbated by coating particles with Suwannee River natural organic matter (NOM). Changes in soil pH were observed in natural soils contaminated with ENMs that were largely independent of ENM type and concentration. These changes may have been due to enhanced release of naturally present pH-altering ions (Mg2+, H+) in the soil, likely via substitution processes. This suggests ENMs will likely be highly retained near source zones in soil and may impact local communities sensitive to changes in pH or nutrient availability. Few studies have investigated the influence of environmental conditions on ENM uptake and toxicity, particularly throughout the entire plant life cycle. Here, soil-grown plants (Clarkia unguiculata, Raphanus sativus, and Triticum aestivum) were exposed until maturity to TiO2, CeO2, or Cu(OH)2 ENMs under different illumination intensities, in different soils, and with different nutrient levels. Fluorescence and gas exchange measurements were recorded throughout growth and tissue samples from mature plants were analyzed for metal content. ENM uptake was observed in all plant species, but was seen to vary significantly with ENM type, light intensity, nutrient levels, and soil type. Light intensity in particular was found to be important in controlling uptake, likely as a result of plants increasing or decreasing transpiration in response to light. Significant impacts on plant transpiration, photosynthetic rate, CO2 assimilation efficiency, water use efficiency, and other parameters related to physiological fitness were seen. The impacts were highly dependent on environmental conditions as well as ENM and soil type. Notably, many of these effects were found to be mitigated in soils with limited ENM mobility due to decreased uptake. These results show that abiotic conditions play an important role in mediating the uptake and physiological impacts of ENMs in terrestrial plants.