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Thesis (Ph. D.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliographical references (leaves 173-178). Also available on the World Wide Web.

Tree diameter, bark thickness and texture, litter bulk density and chemistry, and sprouting ability are a few, species-specific adaptations and properties that may be related to an individual tree stem's potential fire resistance. Based upon these features and others, trees exhibiting similar characteristics have been broadly classified as pyrophytic or pyrophobic. To our knowledge, few if any, research studies have been conducted to determine if tree buds may exhibit speciesspecific fire or heat tolerance. Understanding potential relationships between bud characteristics and fire tolerance may assist prescribed fire managers as they target control of specific undesired tree species while promoting desired tree species. Buds of six common hardwood species in the southeastern U.S. were harvested and exposed to different heat dosages using a propane gas tube burner: red maple (Acer rubrum L.), yellow-poplar (Liriodendron tulipifera L.), American beech (Fagus grandifolia Ehrh.), mockernut hickory (Carya tomentosa Lam.), scarlet oak (Quercus coccinea Münchh.), and chestnut oak (Quercus montana Willd.). These species are commonly categorized as pyrophobic (American beech, red maple, yellow-poplar) and pyrophytic (chestnut oak, mockernut hickory, scarlet oak). Using electrolyte leakage of heated and unheated buds, the mean difference in bud percent mortality between heated and unheated buds was compared by species, functional group, and differing heat dosages. The mean difference in bud percent mortality differed between the heated and unheated buds by species (p < 0.0001). Heated buds of yellow-poplar, mockernut hickory, and chestnut oak displayed similar percent mortality; however, the presumed pyrophytic species had greater heated bud percent mortality (34.0 %) than the pyrophobic species (26.8 %) (p = 0.0003). Heated bud percent mortality differed based upon differing heat dosage levels (height above the propane burner and heat exposure time) and their species-specific interactions. Fire tolerance, as assigned and assessed by features such as bark texture and thickness, may not be directly related to mid-story tree bud physical properties (i.e. length, mass, and diameter) or fire tolerance. Research including additional species, heat dosages, and different sampling times (i.e. late fall vs. late winter) would be valuable for investigating these dynamics further. Deploying a similar, field-scale experiment before and after prescribed burns would be useful to determine how tree buds may respond to different heat dosages that could be exacted during prescribed burns. / Master of Science / Prescribed fire is utilized on millions of acres per year in the southeastern United States. These burns are conducted for a variety of reasons, including: wildlife habitat establishment, restoration, and maintenance; aesthetics; hazardous fuel reduction; and the control of undesired vegetative species. Factors that may influence an individual species' response to fire include, but are not limited to: bark thickness and texture, litter bulk density and chemistry, and resprouting strategy. These traits may differ by species and by the age of a given stem. Few studies have investigated these characteristics in younger tree stems within the southeastern United States. Additionally, few research studies in any ecosystem have investigated potential species-specific tree bud responses to increased heat. Determining if undesired tree species respond differently to heating than desired tree species may provide additional information to assist prescribed fire managers in many locations where vegetation control is a management objective. As a result of this knowledge gap, a research study was designed to investigate these dynamics in the southeastern United States for six common, hardwood tree species: red maple (Acer rubrum L.), yellow-poplar (Liriodendron tulipifera L.), American beech (Fagus grandifolia Ehrh.), mockernut hickory (Carya tomentosa Lam.), scarlet oak (Quercus coccinea Münchh.), and chestnut oak (Quercus montana Willd.). The results suggested that percent bud mortality may be species-specific, but few relationships appeared to be present to relate bud physical characteristics to bud mortality. Additionally, supposed heat tolerance groups assigned to older tree stems based upon traits, such as bark thickness and texture, did not provide a valid assessment of bud mortality. Additional research is needed to understand these dynamics further, including burning under different heat dosages, evaluating additional tree species, and assessing bud mortality resulting from in-the-field prescribed fires.

Mathematical growth and yield models were developed for the major plantation timber species, Cupressus lusitanica, growing in Munessa Shashemene State Forest Project (MSSFP), in Southwest Ethiopia, based on data from 106 temporary sample plots. Stand dominant height development was predicted by Schumacher's growth equation as a function of age and site index, defined as dominant height at reference age of 15 years. Initial diameter distributions of trees were generated using the Weibull probability density function with scale and shape parameters predicted as a function of stand parameters. Stand basal area for unthinned stands was predicted as a function of dominant height, stand age and number of stems using a modified Weibull growth equation. The basal area after thinning was simulated using a single tree diameter increment equation. The mid-diameters of each diameter class were incremented and added to the initial diameter values of each class for subsequent ages which when multiplied by class frequencies and summed gave the stand basal area. Thinnings were simulated using a power function. A compatible tree volume/taper estimation system which determined tree volume and taper was developed. The growth functions were integrated in a logical sequence, using the readily available and user friendly simple spreadsheet package, EXCEL, to produce a whole-stand distance simulation model (SIMCUP). This model also predicted final maincrop yield by size classes. Validation of the volume and diameter distribution models showed that the model (SIMUL) worked satisfactorily. Using SIMUL the effects of different levels of spacing, thinning frequency and thinning intensities on cumulative volume and sawlog volume were investigated. Experimental runs with the most frequently used thinning intensity (37.5% by stem number) at MSSFP showed that the current thinning intensity was too heavy and resulted not only in loss of cumulative volume but also merchantable volume. The cumulative volume of once, twice and three times thinned stands at the age of 25 years could be decreased by between 12.3%, 19.7% and 23% of the unthinned stand respectively. The highest merchantable sawlog volume was with no or one thinning at the age of 7 years with a rotation age of 25 years. In contrast by adopting a 25% thinning intensity the merchantable volume could be increased by between 20.4% to 10.7% relative to current yields for site index classes 27 to 12 and a stand with 1588 stems per hectare respectively. The highest merchantable sawlog volume per hectare to 15 cm top diameter was obtained at the spacing of 2.1 x 2. lm at the rotation age of 25 years The model is intended to promote silvicultural management of C. lusitanica stands in MSSFP, Southwest Ethiopia. Using SIMCUP, different levels of spacing, time of first thinning and alternative thinning intensities have been investigated and appropriate silvicultural measures suggested to achieve higher merchantable volume per hectare.

Over 80% of Sweden's population lives in urban areas, and half of the country's forest visits will thus be in urban woodlands. Social values ​​- how the individual experiences the forest, and the impact of the forest visits on individual health and well-being, are pointing to the importance of managing the urban woodlands. When there comes to the cultivation of the urban woodlands there are usually many opinions to consider. This study aims to investigate the various opinions on the use and forestry in an urban recreation area in ​​the City of Trollhättan. The study addresses both general and in four cases specific suggestions on management methods. Data was obtained from both quantitative and qualitative study through survey, interviews and discussions with the users of the recreation area. Trollhättan's goal with the recreation area is to make it accessible to local residents. The users are mainly influenced by the accessibility therefore clearings and thinnings are appreciated. Clear cuts should be avoided, but can be used as a method if logging residues are removed afterward. Variation is important for the specific areas, the focus is laid on hardwood species. Where hardwood is missing the focus should be to create old and sparse forest.

In British Columbia harvested forests are manually replanted by seasonal workers. Fertilizers contained in perforated paper sachets are often planted with seedlings. There have been anecdotal reports of skin and respiratory illness associated with fertilizer exposure and due to potential metal content in fertilizer source material they may contain metals as contaminants. Workers may also be exposed to pesticide residues on seedlings. This study aimed to characterize fertilizer, metal and pesticide exposure among a sample of B.C. tree planters, and to examine worker respiratory and dermal health. Between May 2006 and April 2007 223 tree planters were interviewed about their respiratory and dermal health, and the exposures of 54 tree planters at five geographically-disperse worksites were monitored. Four worksites were using fertilizer and one was not. The health questionnaire was a modification of the American Thoracic Society standardized questionnaire with questions on dermal health taken from a previous UBC study. Workers were grouped in exposure categories and symptoms analysed using logistic regression. Metals were measured by ICP/MS on post shift hand wipes, full shift air sample filters, in whole blood, bulk soil, seedling root balls, and fertilizer samples. Pesticides were measured on post shift hand wipes and on bulk seedling samples. Using nursery pesticide application records, analyses focused on known pesticides applied to the seedlings at the study sites. Carbamate pesticides were analyzed by HPLC/MS and other pesticides by GC/MS. No evidence was found that tree planters who work with fertilizer are at an elevated risk of exposure to arsenic, lead, cadmium, chromium and nickel relative to other tree planters. Pesticide residues were found on seedlings taken from coastal work sites in April 2007. At coastal worksites the fungicides chlorothalonil and iprodione were found on the skin of workers at low levels (range 0.37 – 106.3 ng.cm² and 0.48 – 15.9 ng/cm² respectively). Work with fertilizer was linked with an increased risk of cough, phlegm, nasal symptoms, nose bleed, and skin irritation. Hygiene conditions at tree planting work sites are very poor. Although measured exposures were low, hygiene conditions should improve to reduce the risk of health symptoms among tree planters.

In British Columbia harvested forests are manually replanted by seasonal workers. Fertilizers contained in perforated paper sachets are often planted with seedlings. There have been anecdotal reports of skin and respiratory illness associated with fertilizer exposure and due to potential metal content in fertilizer source material they may contain metals as contaminants. Workers may also be exposed to pesticide residues on seedlings. This study aimed to characterize fertilizer, metal and pesticide exposure among a sample of B.C. tree planters, and to examine worker respiratory and dermal health. Between May 2006 and April 2007 223 tree planters were interviewed about their respiratory and dermal health, and the exposures of 54 tree planters at five geographically-disperse worksites were monitored. Four worksites were using fertilizer and one was not. The health questionnaire was a modification of the American Thoracic Society standardized questionnaire with questions on dermal health taken from a previous UBC study. Workers were grouped in exposure categories and symptoms analysed using logistic regression. Metals were measured by ICP/MS on post shift hand wipes, full shift air sample filters, in whole blood, bulk soil, seedling root balls, and fertilizer samples. Pesticides were measured on post shift hand wipes and on bulk seedling samples. Using nursery pesticide application records, analyses focused on known pesticides applied to the seedlings at the study sites. Carbamate pesticides were analyzed by HPLC/MS and other pesticides by GC/MS. No evidence was found that tree planters who work with fertilizer are at an elevated risk of exposure to arsenic, lead, cadmium, chromium and nickel relative to other tree planters. Pesticide residues were found on seedlings taken from coastal work sites in April 2007. At coastal worksites the fungicides chlorothalonil and iprodione were found on the skin of workers at low levels (range 0.37 – 106.3 ng.cm² and 0.48 – 15.9 ng/cm² respectively). Work with fertilizer was linked with an increased risk of cough, phlegm, nasal symptoms, nose bleed, and skin irritation. Hygiene conditions at tree planting work sites are very poor. Although measured exposures were low, hygiene conditions should improve to reduce the risk of health symptoms among tree planters.

In British Columbia harvested forests are manually replanted by seasonal workers. Fertilizers contained in perforated paper sachets are often planted with seedlings. There have been anecdotal reports of skin and respiratory illness associated with fertilizer exposure and due to potential metal content in fertilizer source material they may contain metals as contaminants. Workers may also be exposed to pesticide residues on seedlings. This study aimed to characterize fertilizer, metal and pesticide exposure among a sample of B.C. tree planters, and to examine worker respiratory and dermal health. Between May 2006 and April 2007 223 tree planters were interviewed about their respiratory and dermal health, and the exposures of 54 tree planters at five geographically-disperse worksites were monitored. Four worksites were using fertilizer and one was not. The health questionnaire was a modification of the American Thoracic Society standardized questionnaire with questions on dermal health taken from a previous UBC study. Workers were grouped in exposure categories and symptoms analysed using logistic regression. Metals were measured by ICP/MS on post shift hand wipes, full shift air sample filters, in whole blood, bulk soil, seedling root balls, and fertilizer samples. Pesticides were measured on post shift hand wipes and on bulk seedling samples. Using nursery pesticide application records, analyses focused on known pesticides applied to the seedlings at the study sites. Carbamate pesticides were analyzed by HPLC/MS and other pesticides by GC/MS. No evidence was found that tree planters who work with fertilizer are at an elevated risk of exposure to arsenic, lead, cadmium, chromium and nickel relative to other tree planters. Pesticide residues were found on seedlings taken from coastal work sites in April 2007. At coastal worksites the fungicides chlorothalonil and iprodione were found on the skin of workers at low levels (range 0.37 – 106.3 ng.cm² and 0.48 – 15.9 ng/cm² respectively). Work with fertilizer was linked with an increased risk of cough, phlegm, nasal symptoms, nose bleed, and skin irritation. Hygiene conditions at tree planting work sites are very poor. Although measured exposures were low, hygiene conditions should improve to reduce the risk of health symptoms among tree planters. / Medicine, Faculty of / Population and Public Health (SPPH), School of / Graduate