Cabernet sauvignon is the most widely planted red wine grape in California and is valued in the hundreds of millions of dollars. Cabernet sauvignon grapes, when severely vigorous or overcropped, can contain vegetal aromas and flavors when harvested. 3-alkyl-methoxypyrazines are the volatile compounds responsible for this effect and can lower the perceived quality of the wine. Resveratrol is a phytoalexin that has many medical and health benefits and can be found in red wines. An experiment was conducted in Paso Robles, CA to assess the effects of five yield levels, manipulated through cluster thinning, on methoxypyrazine and resveratrol concentrations. Berry weights and chemistry were also measured, in the form of ºBrix, pH, and TA. In 2009 and 2010, no significant statistical differences were found in methoxypyrazines in the harvested grapes. In 2009, resveratrol concentrations were below the detection limits in the wine produced. In 2010, berry weight and chemistry measurements were not significantly different, except for grapes from lightly- and greatly-thinned vines which varied in pH at harvest. The 2009 wines were subjected to discrimination and preference testing by trained tasters. No significant difference was found in the discrimination test and no difference was found using the Friedman and Kramer’s Rank test for the preference test. Only a very slight difference was found between the wines made from unthinned and greatly-thinned vines according to Tukey’s Multiple Comparison Test. The findings of this thesis suggest that cluster thinning does not affect methoxypyrazine and resveratrol concentrations or sensory analysis in Cabernet sauvignon grown on the east side of Paso Roble, CA.

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<p>Forest ecosystems are a significant component of the global carbon (C) cycle. Afforestation is considered a cost-effective and ecologically viable means to sequester atmospheric carbon. However, afforestation requires intensive management practices, including thinning, to maintain and enhance the carbon sequestration capability of the forest. This study examines thinning effects on forest carbon dynamics using eddy covariance (EC) methods. In January 2012, a 74-year-old white pine (<em>Pinus strobus</em>) plantation located in southern Ontario was selectively thinned. Approximately 30% of trees, equating to 2308 m³ of wood (sawlogs and pulpwood), were removed to improve light, water and nutrient availability for remaining trees. Fluxes of energy, water, carbon dioxide (CO₂) as well as meteorological variables were measured throughout the year following thinning and compared to data from the previous 9 years to evaluate effects of thinning on forest carbon dynamics. Mean annual net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (RE) from the 9 years prior to thinning were 290, 1413 and 1118g C m^-2<strong>,</strong> respectively. Post-thinning NEP, GEP and RE were 154, 1509 and 1350 g C m<strong>^-</strong>²<strong> </strong>year^-1, respectively. Post-thinning NEP was significantly less than pre-thinning at the annual time scale due to higher RE, however post-thinning fluxes were still within the range of interannual variability. At this site, approximately 20% of interannual variability in NEP, GEP and RE was explained by environmental conditions. Effects of extreme weather events, particularly heat and drought stress, were demonstrated to negatively impact NEP. Biotic responses to environmental drivers explained the remaining 80% of interannual variability in fluxes. Thinning did not significantly impact these responses. Further, results suggest that thinning may improve tolerance to drought stress by improving water availability for remaining trees. Therefore, thinning has the potential to effectively reduce resource competition and stimulate growth and carbon sequestration in temperate coniferous forests.</p> / Master of Science (MSc)

Data from three long-term field studies with loblolly pine (Pinus taeda L.) plantations were used to examine inequality (Gini coefficient) trends in diameter and the relationship between diameter relative growth rate (r) and initial size. Analysis with two spacing studies shows inequality increases with increasing density. For a given initial density, inequality initially decreases and then begins to increase as trees compete for resources. The slope of the linear relationship between r and relative size also increases with increasing density. The slope is initially negative and switches to positive as competition intensifies. The switch in the slope of the r/size relationship occurs when the crown projection area exceeds 1.05 or when the crown ratio falls below 0.75. These results are consistent with the resource pre-emptive or dominance/suppression theory of intra-specific competition. The r/size trends are not evident when calculations are based on class means as opposed to individual trees. The slope of the r/size relationship is a function of stand height, density, and to a lesser extent, site quality. Density reduction through mid-rotation thinning tends to decrease the slope coefficient. The r/size trends are used to develop a disaggregation model to distribute stand-level basal area growth over an initial tree list. This approach compares well with two other disaggregation models but tends to over predict growth on the largest trees. / Ph. D.

The controversy regarding commercial thinning continues to intensify as pine plantation acreage in the south increases. This controversy has caused industrial and nonindustrial landowners to re-examine the economic returns from their plantation investments. This study was undertaken to develop investment guidelines for the management of loblolly pine plantations. Computer simulation was used to evaluate the effect on present value that four future price/market scenarios, three management regimes, and three mechanized thinning systems can have on current thinning investments. When the economic returns from thinning are compared with a no-thin management regime, simulation results indicate that long-term investment advantages favor thinning only slightly, regardless of the future price/market scenario assumed. This slight difference suggests that individual forest product companies may find other reasons such as wood flow, tax advantages, and future product requirements of their manufacturing facilities to be overriding factors for engaging in commercial thinning. Generally, short-run cost and production differences between thinning systems are more significant than the long-term investment effects. Consequently, the type of mechanized thinning system employed has a negligible impact on the total investment. / Ph. D.

A computer program was developed which provides the necessary information required by landowners to evaluate thinning alternatives in yellow-poplar stands. The program is written Applesoft BASIC for the APPLE II+ microcomputer with a design which emphasizes flexibility and ease of use. The program consists of two primary segments: growth and yield, and economic evaluation. The growth and yield segment is composed of a stand level growth and yield model which consists primarily of a collection of equations specified by Knoebel (1982). The economic evaluation segment calculates two measures of economic performance for before or after taxes. The performance criteria are the present net worth and internal rate of return. Using the computer program developed in the study, optimum thinning regimes were estimated for existing stands of yellow-poplar under a variety of economic and biological conditions. Given a set of benchmark costs and revenues, optimum thinning regimes were estimated for three sites (80, 100, and 120, base age 50). A sensitivity analysis was conducted in which interest rates, thinning costs, and clearcut stumpage values were varied. The optimum regimes expressed varying degrees of sensitivity to changes in the economic parameters. / M.S.

In the oil sand industry, bitumen is separated from sands by aerating the heavy oil so that it can float out of a flotation vessel, leaving the unaerated sands behind. A bubble-against-plate apparatus equipped with a high-speed camera has been developed to record the optical interference patterns of the wetting films formed on a flat surface and subsequently obtain the temporal and spatial profiles of the films offline using the Reynolds lubrication theory. The technique has been used to study the interaction mechanisms between air bubbles and bitumen. It has been found that the film thinning kinetics increases in the order of asphaltene, bitumen, and maltene, and that the kinetics increases sharply with increasing temperature. In addition to obtaining kinetic information, the temporal and spatial profiles of the wetting films have been used to derive appropriate hydrodynamic information that can be used to determine the disjoining pressures (∏) in the wetting films. The results obtained in the present work show that ∏ < 0 for maltene and bitumen, while ∏ > 0 for asphaltene at temperatures in the range of 22 to 80 °C. The disjoining pressure data have been analyzed by considering the contributions from the hydrophobic and steric forces in addition to the classical DLVO forces. It has been found that the hydrophobic force increases with increasing temperature, which corroborates well with contact angle data. Dynamic contact angle measurements show that air bubbles attach on bitumen with relatively small contact angles initially but increase sharply to >90° . The extent and the kinetics of contact angle change increase sharply with increasing temperature. These findings suggest that the primary role of temperature may be to increase iii bitumen hydrophobicity and hence hydrophobic force, which is the driving force for bubblebitumen interaction. A thermodynamic analysis carried out on the basis of the Frumkin-Derjaguin isotherm suggests that the disjoining pressure will remain positive (and hence no flotation) until the hydrophobic force becomes strong enough (due to temperature increase) to overcome the positive disjoining pressure created during the course of bitumen liberation. / Ph. D.

Flotation is an important separation process used in the mining industry. The process is based on hydrophobizing a selected mineral using an appropriate surfactant, so that an air bubble can spontaneously adhere on the mineral surface. The bubble-particle adhesion is possible only when the thin film of water between the bubble and particle ruptures, just like when two colloidal particles or air bubbles adhere with each other. Under most flotation conditions, however, both the double-layer and dispersion forces are repulsive, which makes it difficult to model the rupture of the wetting films using the DLVO theory. In the present work, we have measured the kinetics of film thinning between air bubble and flat surfaces of gold and silica. The former was hydrophobized by ex-site potassium amyl xanthate, while the latter by in-site Octadecyltrimetylammonium chlroride. The kinetics curves obtained with and without theses hydrophobizing agents were fitted to the Reynolds lubrication theory by assuming that the driving force for film thinning was the sum of capillary pressure and the disjoining pressure in a thin film. It was found that the kinetics curves obtained with hydrophilic surfaces can be fitted to the theory with the disjoining pressure calculated from the DLVO theory. With hydrophobized surfaces, however, the kinetics curves can be fitted only by assuming the presence of a non-DLVO attractive force (or hydrophobic force) in the wetting films. The results obtained in the present work shows that long-range hydrophobic forces is responsible for the faster drainage of wetting film. It is shown that the changes in hydrophobic forces upon the thin water film between air bubble and hydrophobic surface is dependent on hydrophobizing agent concentration, immersion time and the electrolyte concentration in solution. The obtained hydrophobic forces constant in wetting film K132 is compared with the hydrophobic forces constant between two solid surfaces K131 to verify the combining rule for flotation. / Master of Science

The major objectives of this study were to: 1. evaluate the financial aspects of improvement thinnings for fuelwood in Appalachian hardwood stands. 2. determine direct net energy values from energy inputs and outputs for fuelwood harvesting in Appalachian hardwoods. The landowners decision on whether or not to thin was greatly influenced by haul distance and his opportunity cost for time spent harvesting wood. Other considerations included the market price for both firewood and firewood stumpage. Two cases were analyzed using discounted cash flows, the first considered the landowner as a firewood consumer. The results of this portion indicated that at low haul distances (< 15 miles) and low opportunity costs ($0 to 5 per hour), the landowner should produce his own firewood. At longer haul distances an open market purchase should be made and at higher opportunity costs a contractor should be hired to harvest the firewood. In the second case, the landowner acted as a firewood producer. The results indicate that at low haul distances and low opportunity costs of harvesting, the landowner can attain reasonable rates of return on the investment (approximately 4% after-tax in real terms). At greater haul distances and higher opportunity costs the investment returns diminish. The second objective concerning energy resulted in favoring larger scale operations at longer haul distances and smaller operations at shorter distances. The major influences on energy values were haul distance and degree of mechanization. Overall, this analysis presents a process for evaluating firewood thinnings and offers the landowner the capability of examining a variety of sites and harvest systems. However, the results should be viewed only as an example situation. / Master of Science

Thinning from above and below were compared using an economic optimizing dynamic program, FORTE (Arthaud 1986). Economically optimal (net present value maximizing) thinning regime and rotation age were determined for benchmark economic and model inputs. Sensitivity of net present value and optimal management regime were tested for varying interest rates (6 or 8%), site indexes (50, 60 and 70, base 25 years), fixed and variable thinning costs, planting density (440, 680 and 910 trees per acre), stumpage prices and thinning type. Given the same assumptions, thinning from below consistently provided the higher net present value for the optimal regime than thinning from above. For the benchmark assumptions, both thinning types had two thinnings in their optimal regimes. Optimal rotation age and thinning timings occur later when thinning from above. Both thinning types provided higher net present values than not thinning under all conditions except pulpwood management. / Master of Science