Conservation and restoration of quaking aspen in the western United States requires an understanding of how and when aspen clones became established, how clones adapt to environmental challenges, and how individual clones interact within stands. I used molecular tools to identify individual clones in a natural population of aspen in southern Utah and detected high and low levels of clonal diversity within stands. Stands with high clonal diversity were located in areas with a more frequent fire history, indicating that fires may have prepared sites for seed germination and establishment over time. Conversely, areas of low clonal diversity corresponded to areas with less frequent fire. The same molecular tools were then used to investigate clonal interactions/succession over relatively recent time. For this portion of the study I sampled small, medium, and large aspen ramets (stems) at 25 subplots within spatially separated one-hectare plots, and mapped the clonal identities. I found that approximately 25% of the clones appeared to be spreading into adjacent clones, while 75% of the clones had a stationary pattern. In the final portion of the study, I again used molecular tools to identify aspen clones and investigated tradeoffs between growth and defense chemistry in mature, naturally-occurring trees. Growth was estimated using a ten-year basal area increment, and the percent dry weight of salicortin, tremulacin, and condensed tannins was measured in the same trees. Overall I discovered evidence for a tradeoff between growth and salicortin/tremulacin, and a marginally significant but positive relationship between growth and condensed tannins.

Mountain headwater catchments in the semi-arid Intermountain West are important sources of surface water because these high elevations receive more precipitation than neighboring lowlands. The hydrology of these mountain catchments is especially important as the region faces water shortages and conflicts. Conifer encroachment on aspen stands has been observed across the western US and can result in a decline in water yield. The overall objective of this study was to further our understanding of hillslope-stream connectivity in a headwater catchment of Northern Utah and any observable differences in this connection between aspen and conifer hillslopes. Hillslopes are the fundamental unit of a watershed. Therefore understanding processes at the hillslope scale is pertinent to managing valuable water resources. However, hillslope hydrology is understudied in the snow-driven, semi-arid west, leaving a gap in our knowledge of how watersheds function. This thesis focuses on how and when hillslope water contributes to stream water: hillslope-stream connectivity. Its specific objectives are (1) to compare peak snow accumulation under aspen and conifer stands, (2) to determine if shallow soil moisture shows organized patterns, indicating hillslope-connectivity and compare these patterns between vegetation types, (3) to examine hillslope-stream connectivity within deep layers of the soil profile and compare times of connectivity between vegetation types and (4) to find any thresholds past which hillslope-stream connectivity begins.

The direct effects of chemically- induced reduced transpiration on soil moisture were studied in a sub -watershed of the greater Logan River drainage. No statistically significant differences occurred among the total amounts of water transpired by the treated and control units. The seasonal low points of soil moisture, in September, showed no significant differences in final moisture retention for the two years studied, either for the control or the treated portions of the study site . The 1967 season showed a lag in soil moisture depletion compared to the 1966 season. Although a later spring in 1967 may have aided in the explanation of this lag, there was good reason to believe that the antitranspirant treatment incurred a significant delay in water use. There was evidence that more effective application of chemicals might have given more positive results.

Censuses of two 20-acre plots in upper Logan Canyon, Utah, were made by the spot-mapping method during 1970 and 1971 to determine the differences in composition and density of breeding-bird populations in aspen stands of significantly different density and stature. The less dense stand of greater average d.b.h., average height and per cent ground cover had 20 breeding species totalling 615 pairs per 100 acres (expressed as equivalent territories). The more dense stand of smaller trees and brushy undergrowth had 14 breeding species with 267.5 equivalent territories per 100 acres. Nine species were found on both areas. Observations of foraging height were made concurrently with recordings of time spent at various methods of feeding- ground, vi foliage, bark, hover, and hawking- for the birds of the more open stand. Comparison showed that more ground- and low bush-nesters were present on the dense, brushy stand whereas more cavity-nesters were found in the larger trees. Cavity excavation was limited to trees of greater d.b.h. and cavity-dependent birds were thus limited by nest-hole availability. The horizontal, heavy branch stubs preferred by pewees and tree swallows and the high perches and open areas of the olive-sided flycatcher were also limited to the less dense stand. Cassin's finches and pine siskins were not found in the dense stand which had fewer invading conifers and was farther from conifer stands. Attributes of the terrain, foraging sites, nest sites, and location of perches were analyzed as possible proximate factors of habitat selection within aspen.

In the Northwest Great Basin, aspen (Populus tremuloides) communities uniquely contribute to the biodiversity of a semi-arid, sagebrush-dominated landscape. In this same region, western juniper (Juniperus occidentalis) is encroaching into aspen stands. This study determined the timing, extent, and some of the effects of this expansion. Aspen stands below 2,133 m elevation were sampled in northwest Nevada, northeast California, and southeast Oregon for density, canopy cover, age, stand structure, and recruitment of western juniper and aspen. Soils and tree litter from both species were collected to analyze the effects of western juniper in areas previously influenced by aspen. Additionally, two large aspen complexes in southeast Oregon were intensively aged to determine disturbance (fire) frequencies. Western juniper encroachment into aspen stands peaked from 1920 to 1939 with 77% of all juniper trees sampled establishing during this period. Five percent were greater than 100 years and none exceeded 145 years. Three-fourths of aspen stands sampled have established populations of western juniper. Twenty-three percent have a dominant canopy of western juniper. Twelve percent of aspen stands sampled were completely replaced by western juniper. Average density of western juniper was 1,573 trees per hectare of aspen. Seventy percent of aspen stands sampled had zero recruitment of new aspen. Within the study area aspen stands averaged 98 years old. Forty-eight percent of stands were greater than 100 years old. There was an inverse correlation between aspen canopy cover and western juniper canopy cover (r��=.80, p=.0001). Soils influenced by western juniper had a higher C:N ratio and pH; higher amounts of salts, lime, and sulfate; and lower amounts of magnesium, iron, copper, and manganese (p<.05). Aspen litter had a lower C:N ratio than western juniper litter (p<.05). Prior to 1870, the two major aspen complexes sampled had mean fire return intervals of 10 and 11 years. However, the most recent disturbance in either complex was 80 to 90 years ago. This lack of disturbance (fire) coupled with aspen stand decadence and low recruitment levels leaves aspen communities in the Northwest Great Basin vulnerable to western juniper encroachment and replacement. / Graduation date: 2000

Bioclimate envelope models are widely used to project potential species habitat under changing climate. Conceptually, these models are also well suited to match natural resource management practices to new climatic realities, for example by guiding species choice in reforestation programs. Nevertheless, uncertainty due to a variety of causes has so far limited the practical application of bioclimate envelope models. The goal of this thesis is to examine sources of uncertainty, to reduce uncertainty if possible, and to develop methodology to systematically deal with the remaining variability in model projections. Secondly, this thesis develops practical climate change adaptation strategies for the forestry sector in western Canada. This requires answering what species should be used for reforestation for a particular site, and subsequently selecting planting stock of the species that is best adapted to current and anticipated environments. Using a novel approach to partition variance in results from multiple model runs, climate data were identified as arguably the most important source of uncertainty. Variation was primarily caused by different general circulation models, followed by different emission scenarios. Also, the method used to interpolate current weather station data was an important contributor to uncertainty at specific locations. Other sources of uncertainty were the choice of predictor variables and different bioclimate envelope modeling methods, which primarily contributed to uncertainty through interaction effects. For example, different modeling methods provided similar habitat projections for western Canada on average, but under certain climate change scenarios their results differed markedly. Given the large uncertainties in model projections, it is important to remember that ultimately, climate change adaptation has to be guided by climate trends that actually materialize. A considerable portion of this thesis therefore analyzes climate trends in western Canada over the past century. In a case study for aspen, it is shown that the combined information from multiple bioclimate envelope model runs, climate trends that have already materialized, and observed climate change impacts can make a strong case for implementing adaptation strategies in central Alberta. Amendments to aspen reforestation practices are proposed, avoiding the use of the species in areas where it is likely to lose habitat in the future, and recommending movement of planting stock so that it is reasonably well adapted under a range of future climate scenarios. / Forest Biology and Management

The modern concept of "biorefinery" is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various biobased products. It includes thermochemical processes such as gasification and fast pyrolysis. In mechanical pulp mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, biosludges and other available fuels such as peat, recycled wood, and paper products. This work is to study co-production of bio-automotive fuels, biopower, and steam via gasification in the context of the mechanical pulp industry.   Biomass gasification with steam in a dual-fluidized bed gasifier (DFBG) was simulated with ASPEN Plus. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150 KWth Mid Sweden University (MIUN) DFBG. The model predicts that the content of char transferred from the gasifier to the combustor decreases from 22.5 wt.% of the dry and ash-free biomass at gasification temperature 750 ℃ to 11.5 wt.% at 950 ℃, but is insensitive to the mass ratio of steam to biomass (S/B). The H2 concentration is higher than that of CO under normal DFBG operating conditions, but they will change positions when the gasification temperature is too high above about 950 ℃, or the S/B ratio is too far below about 0.15. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming. Tar content in the syngas can also be predicted from the model, which shows a decreasing trend of the tar with the gasification temperature and the S/B ratio. The tar content in the syngas decreases significantly with gasification residence time which is a key parameter.   Mechanical pulping processes, as Thermomechanical pulp (TMP), Groundwood (SGW and PGW), and Chemithermomechanical pulp (CTMP) processes have very high wood-to-pulp yields. Producing pulp products by means of these processes is a prerequisite for the production of printing paper and paperboard products due especially to their important functional properties such as printability and stiffness. However, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. In mechanical pulping mills, wood (biomass) residues are commonly utilized for electricity production through an associated combined heat and power (CHP) plant. This techno-economic evaluation deals with the possibility of utilizing a biomass integrated gasification combined cycle (BIGCC) plant in place of the CHP plant. Integration of a BIGCC plant into a mechanical pulp production line might greatly improve the overall energy efficiency and cost-effectiveness, especially when the flow of biomass (such as branches and tree tops) from the forest is increased. When the fibre material that negatively affects pulp properties is utilized as a bioenergy resource, the overall efficiency of the system is further improved. A TMP+BIGCC mathematic model is developed based on ASPEN Plus. By means of this model, three cases are studied:   1) adding more forest biomass logging residues in the gasifier, 2) adding a reject fraction of low quality pulp fibers to the gasifier, and 3) decreasing the TMP-specific electricity consumption (SEC) by up to 50%.   For the TMP+BIGCC mill, the energy supply and consumption are analyzed in comparison with a TMP+CHP mill. The production profit and the internal rate of return (IRR) are calculated. The results quantify the economic benefit from the TMP+BIGCC mill.   Bio-ethanol has received considerable attention as a basic chemical and fuel additive. It is currently produced from sugar/starch materials, but can also be produced from lignocellulosic biomass via a hydrolysis--fermentation or thermo-chemical route. In terms of the thermo-chemical route, a few pilot plants ranging from 0.3 to 67 MW have been built and operated for alcohols synthesis. However, commercial success has not been achieved. In order to realize cost-competitive commercial ethanol production from lignocellulosic biomass through a thermo-chemical pathway, a techno-economic analysis needs to be done.   In this work, a thermo-chemical process is designed, simulated, and optimized mainly with ASPEN Plus. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost.   Calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built at around 200 MW. Cost-competitive ethanol production can be realized with efficient equipments, optimized operation, cost-effective syngas cleaning technology, inexpensive raw material with low pretreatment cost, high-performance catalysts, off-gas and methanol recycling, optimal systematic configuration and heat integration, and a high-value byproduct.

Most clonal plants exhibit a modular structure at multiple levels. At the level of the organs, they are characterized by functional modules, such as, internodes, leaves, branches. At the level of the genetic individual (clone or genet), they possess independent evolutionary and physiological units (ramets). These evolutionary units arise through the widespread phenomenon of clonal reproduction, achieved in a variety of ways including rhizomes, stolons, bulbils, or lateral roots. The focus of this study was Populus tremuloides, trembling aspen, a dioecious tree that reproduces sexually by seed and asexually through lateral roots. Local forest patches in western populations of Populus tremuloides consisted largely of multiple genotypes. Multi-clonal patches were dominated by a single genotype, and in one population (Riske Creek) we found several patches (five out of 17) consisting of a single genotype. A second consequence of modularity is that during the repeated cycle of ramet birth, development and death, somatic mutations have the opportunity to occur. Eventually, the clone becomes a mosaic of mutant and non-mutant cell lineages. We found that neutral somatic mutations accumulated across 14 microsatellite loci at a rate of between 10^-6 and 10^-5 per locus per year. We suggest that neutral genetic divergence, under a star phylogeny model of clonal growth, is an alternative way to estimate clone age. Previous estimates of clone age couple the mean growth rate per year of shoots with the area covered by the clone. This assumes a positive linear relationship between clone age and clone size. We found, however, no repeatable pattern across our populations in terms of the relationship of either shape or size to the number of somatic changes. A final consequence of modularity is that during clonal growth, natural selection is relaxed for traits involving sexual function. This means that mutations deleterious to sexual function can accumulate, reducing the overall sexual fitness of a clone. We coupled neutral genetic divergence within clones with pollen fitness data to infer the rate and effect of mildly deleterious mutations. Mutations reduced relative sexual fitness in clonal aspen populations by about 0.12x10^-3 to 1.01x10^-3 per year. Furthermore, the decline in sexual function with clone age is evidence that clonal organisms are vulnerable to the effects of senescence.

Thermochemical processes for hydrogen production driven by nuclear energy are promising alternatives to existing technologies for large-scale commercial production of hydrogen, without dependence on fossil fuels. In the Copper-Chlorine (Cu-Cl) cycle, water is decomposed in a sequence of intermediate processes with a net input of water and heat, while hydrogen and oxygen gases are generated as the products. The Super Critical Water-cooled Reactor (SCWR) has been identified as a promising source of heat for these processes. In this thesis, the process analysis and simulation models are developed using the Aspen PlusTM chemical process simulation package, based on experimental work conducted at the Argonne National Laboratory (ANL) and Atomic Energy of Canada Limited (AECL). A successful simulation is performed with an Electrolyte Non Random Two Liquid (ElecNRTL) model of Aspen Plus. The efficiency of the cycle based on three and four step process routes is examined in this thesis. The thermal efficiency of the four step thermochemical process is calculated as 45%, while the three step hybrid thermochemical cycle is 42%, based on the lower heating value (LHV) of hydrogen. Sensitivity analyses are performed to study the effects of various operating parameters on the efficiency, yield, and thermodynamic properties. Possible efficiency improvements are discussed. The results will assist the development of a lab-scale cycle which is currently being conducted at the University of Ontario Institute of Technology (UOIT), in collaboration with its partners. / UOIT

Carbon dioxide is considered to be the major source of GHG responsible for global warming; man-made CO₂ contributes approximately 63. 5% to all greenhouse gases. The cement industry is responsible for approximately 5% of global anthropogenic carbon dioxide emissions emitting nearly 900 kg of CO₂ for every 1000 kg of cement produced! Amine absorption processes in particular the monoethanolamine (MEA) based process, is considered to be a viable technology for capturing CO₂ from low-pressure flue gas streams because of its fast reaction rate with CO₂ and low cost of raw materials compared to other amines. However, MEA absorption process is associated with high capital and operating costs because a significant amount of energy is required for solvent regeneration and severe operating problems such as corrosion, solvent loss and solvent degradation. This research was motivated by the need to design size and cost analysis of CO₂ capture process from cement industry. MEA based absorption process was used as a potential technique to model CO₂ capture from cement plants. In this research four cases were considered all to reach a CO₂ purity of 98% i) the plant operates at the highest capacity ii) the plant operates at average load iii) the plant operates at minimum operating capacity and iv) switching to a lower carbon content fuel at average plant load. A comparison among four cases were performed to determine the best operating conditions for capturing CO₂ from cement plants. A sensitivity analysis of the economics to the lean loading and percent recovery were carried out as well as the different absorber and striper tray combinations.