Several restoration methods intended to increase the success of aerially‐seeded perennial grasses were assessed to determine their effects on cheatgrass metrics and soil nutrient bioavailabilities. These methods were: 1) imazapic herbicide application (140 g ai ∙ ha‐1, 210 g ai ∙ ha‐1, and no application [control]), 2) vegetation manipulation treatments (50% sagebrush overstory thinning, 100% sagebrush overstory thinning, sagebrush overstory and/or vegetative thatch burning, and no manipulation [control]), and 3) alternative seeding treatments (aerial seeding with raking, aerial seeding with activated carbon [AC] addition, aerial seeding with sucrose addition, and regular aerial seeding [control]). Treatments were arranged in 3‐way factorial designs, which allowed main effects and interactions between treatments to be assessed. Responses were followed for two growing seasons following treatment. Main effects of treatments and their interactions on cheatgrass metrics are described in Chapter 2. Herbicide reduced cheatgrass weights and tiller and spikelet numbers in 2009, but these variables were greater than in no‐herbicide plots in 2010. Burning decreased cheatgrass densities but increased weights and tiller and spikelet numbers in both years. One hundred percent sagebrush thinning resulted in greater cheatgrass weights and tiller and spikelet numbers in both years and greater densities in 2010. Sucrose addition decreased cheatgrass weights and tiller and spikelet numbers in 2009, but increased these variables in 2010. An interaction between AC and herbicide treatment was observed, with AC potentially sequestering and lessening the negative effect of herbicide on cheatgrass. Aerial seeding with raking and 50% sagebrush thinning treatments were not found to significantly affect cheatgrass either year. The effects of treatments (herbicide, 50% sagebrush thinning, aerial seeding on snow, and aerial seeding with raking treatments omitted) on soil nutrient availabilities are described in Chapter 3. We used ion exchange resin (IER) membrane probes to measure extractable quantities of 15 ions over three time periods following treatment applications. Burning resulted in short‐term increases in many soil nutrient availabilities, including nitrate (NO3 ‐), phosphate (H2PO4 ‐), and sulfate (SO4 2‐). Sucrose addition reduced availabilities of NO3 ‐ and H2PO4 ‐ during the first winter and growing season. No changes were detected with AC addition or 100% sagebrush thinning during any sampling time.

Made available in DSpace on 2014-12-17T14:07:22Z (GMT). No. of bitstreams: 1 RicardoPSD.pdf: 1922919 bytes, checksum: 54dfc0d5fe53e83de5babd021bd83da6 (MD5) Previous issue date: 2007-03-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 ?C/min, 10 ?C/min and 20 ?C/min, with final temperatures of 850 ?C, 950 ?C and 1050 ?C. Discontinuous cycles with rates of 10 ?C/min or 15 ?C/min up to 600 ?C and a rate of 20 ?C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 ?C and fast fire sinterization up to 950 ?C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries / A taxa de aquecimento ? uma das principais vari?veis que determinam um ciclo de queima. Em processos industriais que utilizam elevadas temperaturas, uma maior velocidade de queima pode proporcionar uma diminui??o do custo de produ??o e aumento da produtividade. A ind?stria de cer?mica estrutural pouco tem investigado sobre a utiliza??o de ciclos de queima mais r?pidos e eficientes. Entretanto, uma das possibilidades que visam ? moderniza??o do setor ? a utiliza??o de fornos a rolos e a inclus?o do g?s natural como combust?vel. Neste contexto, o objetivo deste trabalho ? investigar o efeito da velocidade de aquecimento nas propriedades tecnol?gicas de produtos para cer?mica estrutural. Foram caracterizadas mat?riasprimas argilosas dos principais p?los cer?micos de Rio Grande do Norte. Algumas das mat?riasprimas caracterizadas foram formuladas visando obter as melhores propriedades f?sicas e mec?nicas. Em seguida, foram selecionadas mat?riasprimas e formula??es para o estudo da influ?ncia na taxa de aquecimento nas propriedades finais dos materiais cer?micos. As amostras foram conformadas por prensagem e extrus?o e submetidas ?s taxas de 1 ?C/min, 10 ?C/min e 20 ?C/min, com temperaturas finais de 850 ?C, 950 ?C e 1050 ?C. Tamb?m foram investigados os ciclos descont?nuos com taxas de 10 ?C/min ou 15 ?C/min at? 600 ?C e taxa de 20 ?C/min at? a temperatura final. Foram determinadas propriedades tecnol?gicas para todas as amostras e realizada a an?lise microestrutural em algumas condi??es de queima. Resultados indicam que ? poss?vel utilizar ciclos de queima mais r?pidos e eficientes que os atuais, limitando apenas algumas massas argilosas para certas condi??es de queima. Os melhores resultados foram obtidos para as amostras submetidas aos ciclos lentos at? 600 ?C e sinteriza??o com queima r?pida at? 950 ?C. Este trabalho apresenta como contribui??o original a utiliza??o de uma taxa de queima r?pida para mat?riasprimas e formula??es argilosas, procurando determinar as condi??es ideais de massas e de processamento para o uso de um menor tempo de queima, possibilitando assim, a utiliza??o de fornos a rolos e do g?s natural pelas ind?strias de cer?mica estrutural

Fire is the primary natural disturbance vital to the ecological integrity of Quetico Provincial Park, Ontario, Canada. A new provincial park planning process (i.e., Class Environmental Assessment) has required the review of Quetico’s Fire Management Plan. To support this review, large and severe (stand-replacing) Quetico fires were studied using 1966 Ontario Ministry of Natural Resources (OMNR) forest resource inventory (FRI) mapping. A Geographic Information Systems (GIS) database of the FRI was created and updated with the OMNR digital fire atlas. This database was used as a time-since-fire and fire interval dataset to estimate fire frequency. It also served to archive the 1966 FRI for the largest protected area in the transition between the Boreal and Great Lakes-St. Lawrence forest regions. Non-parametric (Kaplan-Meier) survival analysis was used to estimate survival functions and mean fire intervals (i.e., the expected time between two consecutive stand-replacing fires for any location within the Park). Previous studies that have used Kaplan-Meier survival analysis methods have based fire frequency estimates solely on time-since-fire data. However, time-since-fire data cannot be equated with fire interval data when using non-parametric methods. At least one fire interval is required to obtain reliable results. The mean fire interval for the entire 475,782 ha Park between the years 1668 and 2007 was 230 years. Performing the analysis on various geographic and temporal partitions revealed fire frequency spatial and temporal variability. A constant (independent of time-since-fire) probability of burning was not observed for Quetico which is contrary to accepted conjecture for northwestern Ontario boreal/mixed-wood forests. A current fire cycle was also estimated for the Park (342 years) using the digital fire atlas. The results suggested that use of historical static fire frequency estimates as fire management prescriptions may not be justified given considerable fire frequency temporal variability. The observed fire frequency spatial variability suggests that studies should be undertaken at coarser scales than is the norm to characterise the regions fire regime in support of landscape level fire management planning.

Fire is the primary natural disturbance vital to the ecological integrity of Quetico Provincial Park, Ontario, Canada. A new provincial park planning process (i.e., Class Environmental Assessment) has required the review of Quetico’s Fire Management Plan. To support this review, large and severe (stand-replacing) Quetico fires were studied using 1966 Ontario Ministry of Natural Resources (OMNR) forest resource inventory (FRI) mapping. A Geographic Information Systems (GIS) database of the FRI was created and updated with the OMNR digital fire atlas. This database was used as a time-since-fire and fire interval dataset to estimate fire frequency. It also served to archive the 1966 FRI for the largest protected area in the transition between the Boreal and Great Lakes-St. Lawrence forest regions. Non-parametric (Kaplan-Meier) survival analysis was used to estimate survival functions and mean fire intervals (i.e., the expected time between two consecutive stand-replacing fires for any location within the Park). Previous studies that have used Kaplan-Meier survival analysis methods have based fire frequency estimates solely on time-since-fire data. However, time-since-fire data cannot be equated with fire interval data when using non-parametric methods. At least one fire interval is required to obtain reliable results. The mean fire interval for the entire 475,782 ha Park between the years 1668 and 2007 was 230 years. Performing the analysis on various geographic and temporal partitions revealed fire frequency spatial and temporal variability. A constant (independent of time-since-fire) probability of burning was not observed for Quetico which is contrary to accepted conjecture for northwestern Ontario boreal/mixed-wood forests. A current fire cycle was also estimated for the Park (342 years) using the digital fire atlas. The results suggested that use of historical static fire frequency estimates as fire management prescriptions may not be justified given considerable fire frequency temporal variability. The observed fire frequency spatial variability suggests that studies should be undertaken at coarser scales than is the norm to characterise the regions fire regime in support of landscape level fire management planning.