Proper management of uneven-aged interior Douglas-fir (Pseudotsuga menziesii var. glauca) stands is important for British Columbia’s central and southern interior. These stands constitute one of main components of the operable forest land in these areas, with easy access from main roads and towns. This study focused on the growth of uneven-aged Douglas-fir stands after pre-commercial thinning (spacing), with an impetus to improve upon current management practices. Data were collected from 24 permanent sample plots which were established near Williams Lake, British Columbia in 1989; thinning took place between 1990 and 1991. Three measurements have been made post-treatment: 1993, 1997 and 2004. The plot data were used to analyze different growth responses among three different spacing regimes (standard, 3 m clumped and 5 m clumped spacing) and a control. Analyses were performed at both the stand and tree level. The growth of basal area per ha, quadratic mean dbh, volume per ha and Lorey’s height were used for stand level analyses. At the tree level, dbh, height, basal area and volume were the variables of interest. At the stand level, mortality increased (7.1 to 107.1 stems/ha) and ingrowth decreased (2.4 to 8.6 stems/ha) for the second growth period (1997-2003), compared to the first growth period (5.8 to 107.1 stems/ha and 5.0 to 12.4 stems/ha, respectively). No significant differences in annual growth of quadratic mean dbh, basal area and volume per ha and Lorey’s height were noted between the different spacing regimes and the control. At the individual tree level, the 5 m clumped spacing regime usually had the highest dbh, basal area and volume growth for both growth periods. The one exception was for height growth, when analyzed using mixed-effects modeling, where no significant differences were found. Trees on the other two spacing regimes also had higher growth in dbh, basal area, and volume than trees on the control plots. The positive growth response to the spacing treatments at the single tree level was obtained without a reduction in growth at the stand level. This growth increase will result in the residual trees reaching larger sizes more quickly than they would have with no treatment, leading to improved mule deer winter range habitat and higher timber values. / Forestry, Faculty of / Graduate

There is a growing body of research that indicates that effective management of school resources influences learning and teaching (Chiu & Khoo, 2005; Murtin, 2013). Arguably, schools with better management tend to have better performance on a wide range of dimensions; they are more productive, grow faster and achieve better academic achievement result (Williams, Kirst & Haertel, 2005). It is, therefore, crucial to have effective leaders who will manage the education system towards national goals. According to the Department of Basic Education (2016), all learners have the right to have access to relevant and meaningful learning experiences and opportunities. Further to this, the school community has the right to a safe and secure learning environment, otherwise known as good school climate (Kelley, Thornton & Daugherty, 2005). This brings about the importance of the principals of the school who have the responsibility for resource management and the effectiveness of learning in the school. The study on the impact of the principals’ management practices on school climate of public secondary schools in Pretoria is important to understand how to improve the standard of education in South Africa. Relatively little previous research has investigated the mechanisms by which a principal’s management practices pose an effect on the school climate. The current study examined the impact of the principal’s management practices on the school climate by sampling teachers and non-teaching staffs from three schools in Pretoria, Gauteng province. The school climate was measured with the three sub-scale of organisational climate index (collegial leadership, professional and principal’s leadership). Survey data was obtained from school teachers to measure the staff’s perception of their principal’s management practices. This study reveals the effect of the management practices of principals in motivating teachers to perform, remain loyal to their schools and support the principals even when it seems there are several challenges. On the other hand, the management practices of principals create context and some positive school climates for teachers working in these schools. / Dissertation (MEd)--University of Pretoria, 2020. / Education Management and Policy Studies / MEd / Unrestricted

Best management practices (BMPs) are used in the nursery and greenhouse industry to increase production efficiency, and also serve to help meet clean water limitations on contaminants entering waters such as the Chesapeake Bay Watershed. Research is lacking on which BMPs are most widely used or most efficacious for Virginia nursery and greenhouse growers. Objectives of this work were to determine BMP use, barriers to adoption, and scientific efficacy. We conducted a survey of Virginia growers to find the 1) most widely used BMPs, 2) reasons behind BMP use, and 3) any barriers to BMP adoption. Sixty growers (17%) responded to the survey. The most widely used BMPs included irrigation scheduling, integrated pest management, optimized irrigation efficiency, plant need based watering, grouping plants by water needs, on-site water capture and collection, and use of controlled-release fertilizers (CRFs). Cost was a barrier to BMP adoption, and environmental concern was a commonly reported reason for BMP use. We documented the science supporting selected water-related BMPs (grass buffer strips, CRFs, and irrigation optimization BMPs). Providing the science supporting BMP use gives growers confidence in implementing BMPs to limit water contamination, and prevent waste. / Master of Science

The agriculture community is faced with new challenges to increase food production on a limited amount of suitable land to keep up with the growing population. Fertilizers and intensive cropping are needed to meet food demand, but these practices contribute to environmental degradation due to nutrients and sediment leaving fields and entering waterbodies. Non-point source (NPS) pollution from agriculture has been scrutinized for significantly contributing to eutrophication and hypoxic dead zones. To reduce the harmful impacts of NPS pollution from agriculture, producers and land users have implemented in-field and edge-of-field Best Management Practices (BMP). Water and Sediment Control Basins (WASCoBs) are an example of an in-field BMP that has helped reduce erosion and sediment loading of receiving waters. Cover crops are another in-field BMP that have been used to mitigate erosion and nutrient leaching. The impacts of WASCoBs paired with cover crops on water quality, specifically nutrient loading, is lacking in the current literature and was the focus of this research. Our study site was located in Menard County near Atterberry, IL. The farm had relatively steep topography (5-18% slopes) and suffered from severe gully erosion. In 2018, the Natural Resource Conservation Service (NRCS) partnered with the landowner and installed a series of WASCoBs to address the erosion issues. Along with the NRCS and landowner, we worked with the Illinois Farm Bureau (IFB) to investigate the impacts of WASCoBs and cover crops on nutrient and sediment runoff, hydrology, and crop yields.Four sub-watersheds were included in the study: 1) a 1.5-hectare basin treated with a WASCoB; 2) a 1.4-hectare basin treated with a WASCoB and a cover crop; 3) a 0.2-hectare gully drained watershed treated with a cover crop; and 4) a control, 3.8-hectare gully-drained watershed. ISCO automated water samplers collected runoff from storm events in a time-weighted composite sampling regime. The measured water quality parameters were total suspended solids (TSS), ammonium-nitrogen (ammonium-N), nitrate-nitrogen (nitrate-N), dissolved reactive phosphorus (DRP), and total phosphorus (TP). The WASCoB treatment reduced TSS by 98.5-99.8%, TP by 83.8-97.4%, ammonium-N by 42.3-82.9%, and nitrate-N by 32.0-59.6%, respectively. Cover crop impacts on the water quality parameters were not detected, due to poor gemination of the annual rye cover crop. The water quality improvement WASCoBs are a potential tool for farmers and land managers to reduce loading of nutrients and sediment to receiving waters.

Includes bibliographical references / The African Growth and Opportunity Act (AGOA) is a unilateral trade policy concession governing United States - Sub-Saharan Africa (SSA) trade and investment relations. AGOA provides United States market access for 40 SSA countries, including South Africa. This piece of legislation has the fundamental objective of facilitating the global integration of SSA countries into the world economy by extending preferential access to the United States market for exporters from eligible countries. Over the past decade, AGOA has emerged as a topical issue as scholars and policy makers sought to understand its impact on SSA, especially South Africa. This has been awarded more impetus given its pending expiration in 2015. This, naturally, raised questions about the performance of United States preference programs (such as AGOA) as part of a larger ongoing debate on the form that United States preference programs may take in the foreseeable future. With South Africa facing a serious opposition to inclusion in the next shape of AGOA given the number of trade agreements South Africa has signed with countries that are competitors to United States in certain product categories. This study will seek to highlight the importance of the AGOA dispensation to South Africa, and through that analysis make a case for the continued inclusion of South Africa in the future trade dispensations that may develop. This study focuses on two research objectives; firstly, the study seeks to assess the extent to which increased preferential access to the United States market has translated into a real and tangible increase in exports from South Africa to the United States. Secondly, the study seeks to identify the areas where South Africa and the United States have high trade potential, and help make a case for inclusion of these high potential trade products in the next iteration of the AGOA dispensation. In achieving the first research objective, the study carried out a detailed trade statistics analysis with the hope of gaining greater understanding of the extent to which AGOA has influenced trade patterns between the United States and South Africa. South Africa's trade figures show that the United States is an important trade partner. A key conclusion that can be drawn from the analysis is the observation that a fair amount of growth in South Africa's exports to the United States is fundamentally characterized by two key aspects namely; growth in specific commodities and an export base that is becoming gradually concentrated over time. This implies that trade between South Africa and the United States is shifting towards a new focus in line with AGOA incentives and by extension one may conclude that South African firms are utilizing the market opportunities and the networks that enable them to effectively exploit the United States market. In fulfilling the second research objective, the detailed trade potential analysis that is propped up by a robust analysis of trade trends was carried out. The trade potential analysis identified thirteen commodity groups as having high potential for further exports into the United States market, and Pearls, precious stones and metals were identified as having the highest indicative trade potential, although the picture changes as the data is further disaggregated. This suggests that there is enormous potential and a great scope for export of pearls, precious stones and metals to the United States.

The fate and distribution of copper-based crop protectants, applied to tomato fields to protect against disease, were investigated in a greenhouse-scale simulation of farming conditions in a coastal environment. Following rainfall, 99% of the applied copper was found to remain on the fields sorbed to the soil and plants; most of the soil-bound copper was found sorbed to the top 2.5 centimeters of soil. Of the copper leaving the agricultural fields, 82% was found in the runoff with the majority, 74%, sorbed to the suspended solids. The remaining copper, 18%, leached through the soil and entered the groundwater with 10% in the dissolved phase and 8% sorbed to suspended solids. Although only one-percent of the copper was found to leave the field, this was sufficient to cause high copper concentrations (average 2102 ± 433 mg/L total copper and 189 ± 139 mg/L dissolved copper) in the runoff. Copper concentrations in groundwater samples were also high (average 312 ± 198 mg/L total copper and 216 ± 99 mg/L dissolved copper). Sedimentation, a best management practice for reducing copper loadings, was found to reduce the total copper concentrations in runoff by 90% to a concentration of 245 ± 127 mg/L; however, dissolved copper concentrations remained stable, averaging 139 ± 55 mg/L. Total copper concentrations were significantly reduced by the effective removal of suspended solids with sorbed copper. This research was supported by a grant from the Virginia Department of Agriculture and Consumer Services. Funding was also provided by Sea Grant. / Master of Science

Increasing awareness of hypoxia in coastal marine regions across the globe has led to creation of nutrient reduction strategies to protect water resources and organisms living in affected waters. In the Mississippi River Basin, the Governor’s Action Plan has called for a 45% load reduction of both, total nitrogen (N) and total phosphorus (P), to reduce the Gulf of Mexico hypoxic zone to a manageable size. Objectives of this dissertation aimed to determine nutrient reduction efficiencies of low-grade weirs, and to evaluate abundance and composition of microbial communities involved in key processes of denitrification following low-grade weir implementation in the Mississippi Delta. Results of this dissertation evidenced the efficiencies of low-grade weirs to reduce nutrient runoff to downstream waters as a viable BMP. Average median load reductions in N, P, and sediment of -5%, 23%, and 29%, respectively, were determined in ditches with low-grade weirs. Results highlighted more efficient reductions in P and sediment, and greater variability in N reductions during storm events, prompting management considerations toward BMP successes and limitations. Valuable insight towards seasonal nutrient fluxes in agricultural runoff due to spring fertilizer applications, increased rainfall patterns in the winter and spring, and drying-wetting cycles, was also evidenced by the data collected. It was determined that utilizing a three-scale sampling regime was most effective for capturing patterns of microbial community abundance and composition in ditches with low-grade weirs. Preliminary evidence towards weir proximity influencing microbial community abundance, and relationships between microbes and soil carbon and N was also found. Utilizing the three-scale sampling regime, microbial communities in multiple drainage ditches, with and without weirs, were investigated. Outcomes showed that weirs increased soil moisture, which subsequently increased functional gene abundance of 16S rRNA and nirS. Furthermore, weir implementation and associated constructions were not found to directly influence microbial community diversity, abundance, or chemical parameters. Results from this dissertation support the potential benefits of weirs to create suitable environments to physically reduce P and sediment loads and for denitrifying microbes to remediate N from agricultural runoff.

Due to development of once natural landscapes, also referred to as urbanization, stormwater management has evolved in an effort to address and counteract impairment of waterways in the United States by extensively implementing best management practices (BMPs) or Green Stormwater Infrastructure (GSI). Facilities are installed without any requirement of long-term monitoring; instead relying on lab-tested or assumed pollutant removal efficiencies that often do not translate into field implementation and do not perform as intended and required by regulatory agencies. Monitoring studies have often been applied with variable standards, which lead to inconsistent results and inconclusive data. This study aims to synthesize essential components of a GSI monitoring program based on a review of existing programs (Technology Assessment Protocol – Ecology [TAPE], Technology Assessment Reciprocity Partnership [TARP], etc.). Data from past protocols was used in tandem with historic precipitation data to develop a methodology for creating a local or small region-specific protocol. This methodology was applied to the case study area of Fairfax, Virginia. Results from the study indicate that historic precipitation data and past protocol recommendations can be effectively applied in a local setting to create a more suitable protocol adapted for GSI monitoring in order to confirm designed efficiency. / Master of Science

Construction and maintenance can have huge implications on the long-term functioning of GSI facilities. GSI facilities investigated were bioretention, permeable pavement, sand filters, infiltration trenches, and vegetated swales. This study first highlights the most important construction and maintenance items based on relevant studies and state stormwater manuals. Fairfax County, VA was used as a case study to evaluate the County's current stormwater program and illuminate common maintenance issues found for each GSI type. Data analysis of 3141 inspection records illustrated particular deficiencies for each GSI type and that there are differences between public and private facilities, most likely depending on site conditions and frequency of routine maintenance. Sediment accumulation was found to be the most common maintenance issue (27.8% of inspections), supporting the importance of adequate pretreatment and good housekeeping when implementing GSI. The Northern Virginia Soil and Water Conservation District (NVSWCD) performed a study surveying 63 public bioretention facilities in which they measured ponding depth, filter media depth, ponding area, and infiltration rates. The NVSWCD concluded that deficiencies found in facilities could mostly be attributed to inadequacies during construction. By comparing current post-construction inspections performed by the County to the NVSWCD data, it was found that these County inspections are failing to detect these inadequacies in bioretention facilities from improper construction. It is recommended that MS4s thoroughly record and track construction and post-construction inspection items to improve the longevity of its facilities and better inform future decision making regarding GSI. / Master of Science

Drainage ditches, or grassed waterways, collect nutrient-laden runoff from agricultural fields and transport it to nearby waterbodies. The high nitrogen and phosphorus content in this water leads to negative effects, such as eutrophication in the receiving waters. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors are intended to reduce flow rate and stimulate denitrification and sedimentation. Using experimental ditch segments and simulated runoff, this study evaluated nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors and 3) vegetated ditches with combination woodchip and biochar bioreactors. Biochar was added in an effort to increase phosphorus removal. Inlet and outlet concentrations of nitrate, ammonium and phosphate were measured for each of the three treatments in triplicate. There were no statistically significant differences between treatments on load removed for any of the three nutrients of interest. Issues in measuring outlet flow rate made drawing definitive conclusions on nutrient load reductions difficult. Further experimentation using adjusted outlet flow measuring methods and bioreactor design would help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology in agricultural grassed waterways. / Master of Science / Drainage ditches, or grassed waterways, are located at the edge of agricultural fields where runoff migrates naturally. These ditches help to direct runoff from the field to receiving waterbodies while reducing erosion. Agricultural runoff often contains high levels of nitrogen and phosphorus from fertilizer added to promote crop growth. When runoff with a high nutrient content reaches a waterbody, it reduces the quality of the water for the plants and animals that live in it and for human recreation or consumption. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors have the potential to remove nitrogen from the water by creating optimal conditions for the microorganisms that transform nitrogen in the water to nitrogen in the air. Phosphorus removal has the potential to be enhanced by in-ditch bioreactors that reduce flow and allow for phosphorus to settle out of the water. In addition, settling of phosphorus may be increased by adding a material, such as biochar, that phosphorus can attach to. Using experimental ditch segments and simulated runoff, this study looked at nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors installed and 3) a vegetated ditch with combination woodchip and biochar bioreactors installed. Concentrations of two nitrogen compounds and one phosphorus compound were measured before and after passing through each ditch. There were no significant differences between any of the three ditch types on how much of each compound they could remove. These results are inconclusive due to inaccuracies in measuring flow rate at the outlet of the ditches. Further experimentation using improved flow measuring techniques and bioreactor designs would likely help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology.