Thesis--University of Washington. / Vita. Another copy has number: Thesis 27746. Bibliography: leaves [292]-300.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [71]-79.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 110-116). Also available on the World Wide Web.

Thesis (M.S.) University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 18, 2007) Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [128]-135.

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Kenya's economy depends largely on agriculture for growth and development and yet only 20% of the total land area lies in high potential farming areas that support 80% of the total population and 50% of the total livestock in the country. Intensified cropping as a result of the high population concentration on high potential areas has put pressure on land and other resources to an extent that potential productivity of these areas has been degraded. Loss of soil nutrients through soil erosion has caused decreased food production, deterioration of croplands and, siltation and eutrophication of water bodies. Over reliance on forest resources by the communities in the study area has led to deforestation as well as the general disturbance of watershed areas and its functions. There is need therefore to find alternative ways of retaining and/or restoring lost fertility through community participation so as to increase food production. The aim of this study was to investigate the socio-economic factors that influence farmer participation in agroforestry activities in Moiben and Ainabkoi Divisions of Uasin-Gishu District. Data was collected using participatory methods. One set of data was collected using a questionnaire that had both open and closed ended questions. Through random sampling, a total of 300 farmers were interviewed. Additionally, key informants from various government departments were interviewed. The other set' of data was obtained through resource assessment in a forest adjacent to the communities in the study area. This study found that the majority of the farmers had not practised agroforestry despite many being aware of it. Socio-economic problems that hindered them from adopting and practising agroforestry technologies included lack of forest extension services as a reliable source of information about suitable tree species, and how to plant and best locate them within the farm, gender-related issues hindered vulnerable groups, particularly women and children and lack of secure land tenure was a disincentive to those farmers who live on trust land and the married sons who have not been allocated land by their parents. Farm labour during peak farming period was found to scarce due to farmer prioritisation of farm activities. Farmers mentioned that trees occupy land that is already becoming scarce and only give returns in the long term yet farmers need immediate benefits. Forest extension services were ineffective due to scarcity of resources that would enable officers to discharge their duties efficiently. Resources within the gazetted forests were being over exploited since that was the only source with cheaply available wood and non-wood products. It was also found in this study that the majority of the farmers faced environmental problems that included soil erosion, decreased crop yields as well as shortage of wood products. In the future, affordable extension techniques need to be employed in order to reach the farmers. The current regulations that govern private land ownership should be streamlined so as to enable all family members participate in decision-making on utilisation of land. There is need to incorporate agroforestry adult literacy classes as well as in local school curricula. Being multi disciplinary, agroforestry can be spread to the farmers by involving stakeholders at every stage. The current crop of extension agents should be re-trained or should be attending in-service courses regularly. This could transform them into facilitators. Further research should be done on farmers' attitude towards trees, cheaper techniques of disseminating information on agroforestry should be investigated while the current extension techniques should be evaluated for their strengths and weaknesses. / AFRIKAANSE OPSOMMING: Kenia se ekonomie is grootliks afhanklik van landbou vir groei en vooruitgang. Slegs 20% van die totale beskikbare landbougrond in hoe-potensiele landbou areas ondersteun 80% van die totale bevolking en 50% van die totale lewende hawe. Hoë bevolkingsdigtheid vereis intensiewe oesverbouing wat weer hoë druk op landbougrond en ander bronne plaas. Dit het tot gevolg dat die moontlike produktiwiteit van hierdie areas agteruit gaan. Die verlies van voedingstowwe as gevolg van gronderosie het verlaagde voedselproduksie, agteruitgang van landbougrond en toeslikking van waterbronne tot gevolg. Die algehele afhanklikheid van gemeenskappe op bosprodukte het tot ontbossing en algemene versteuring van opvanggebiede gelei. Dit is dus noodsaaklik om alternatiewe maniere te kry om die grondvrugbaarheid te behou en/of te herstel deur gemeenskapsamewerking en om sodoende voedselverbouing te verhoog. Die doel van die studie is om ondersoek in te stel na die sosio-ekonomiese faktor wat die landbouer se samewerking in Moiben en Ainabkoi gebiede van Uasin-Gishu distrik beïnvloed. Die inligting is ingesamel deur deelnemende metodes te gebruik. 'n Vraelys met keuse- en ander soortige vrae is gebruik om die inligting in te samel. 'n Totaal van 300 landbouers is deur toevallige keuring ondervra asook segsmanne van verskeie regeringsdepartemente is vir inligting genader. Nog inligting is verkry deur hulpbronopnames in die gebied aangrensend tot die gemeenskappe van die studiegebied. Hierdie studie het gewys dat die meerderheid van die landbouers nie agrobosbou toepas nie alhoewel hulle wel daarvan bewus is. Sosio-ekonomiese faktore wat hulle verhinder om agrobosbou toe te pas sluit die gebrek aan lanboudienste as betroubare bron van inligting oor geskikte boomspesies en boomaanplantingmetodes in. Ook het geslagverwante probleme, kwesbare groepe veral vroue en kinders, gehinder. 'n Tekort aan gewaarborgde grondbesit vir landbouers wat op trustgrond werk en die getroude seuns aan wie nog nie grond deur hulle ouers toegeken is nie, was terughoudende faktore. Plaasarbeid was ook nie standhoudend nie. Landbouers het ook gevoel dat bome waardevolle en skaars grond gebruik en slegs voordele op die lange duur gee terwyl die landbouers die voordele dringend moet kan benut. Landbouvoorligtingsdienste was nie effektief nie as gevolg van die skaarsheid van hulpbronne wat personeel kan help in hulle verpligtinge. Voedsel- en ander bronne uit die bosreservate word uitgeput aangesien dit die enigste goedkoop bron is. Die studie het ook bevind dat die meerderheid landbouers omgewingsverwante probleme soos erosie en swak oeste asook 'n tekort aan houtprodukte ondervind. Voortaan behoort bekostigbare landbouvoorligtingstegnieke gebruik te word om landbouers te bereik. Die huidige bepalings wat privaatbesit reguleer behoort vereenvoudig te word sodat al die lede van een gesin 'n aandeel kan hê in die besluitnemingsproses oor die gebruik van die grond. Daar is ook 'n behoefte aan volwasse-geletterdheidsonderrig vir landbouers as deel van die skoolprogram. Aangesien agrobosbou verskeie gebiede raak, kan landbouers in enige stadium betrek word. Die huidige groep personeel behoort heropgelei te word of behoort gereeld indiensopleiding te ontvang. Dit kan hulle tot fasiliteerders bevorder. Verdere navorsing is nodig om landbouers se houding teenoor bome te verander en om goedkoper landbouvoorligtingstegnieke vir agrobosbou te vind. Huidige landbouvoorligtingstegnieke behoort ook ondersoek te word om die sterk - en swakpunte te bepaal.

Timber is a local, sustainable and valuable building material, but it is highly variable compared to other building materials (e.g. concrete, steel). The quality of wood is its suitability for the end-user, in this case the construction industry (via timber processors). Douglas-fir is a tall conifer capable of producing high construction grade timber. Native to the north-western Pacific regions of America and Canada, Douglas-fir was introduced to the UK in 1827. After World War 1, the planting of conifers greatly increased due to the establishment of the Forestry Commission. Despite being a high value timber crop in North America, Douglas-fir was not highly utilised in Great Britain due to a perceived lack of suitable growing sites (requiring nutrient-rich soil) and a lack of knowledge on its qualities (mechanical). Consequently, it still to this day covers a relatively small amount of the total UK conifer plantation area, but under predicted climate change projections an increased range of sites will become more suitable for Douglasfir, thus investigation now is imperative. To investigate the quality of Douglas-fir timber and its biological variation, a variety of sites were sampled in Scotland and Wales. The variation in the physical and mechanical properties of UK-grown Douglas-fir were investigated to determine how strength and stiffness of Douglas-fir compares to other commercially important timber species in the UK (as well as compared to Douglas-fir grown in different countries). Standing and felled tree measurements relating to tree architecture and important for timber volume (e.g. size, height, branching habits and taper) were collected in the forest. This was followed by laboratory testing of wood samples obtained from those trees to determine important raw material properties. Ultimately this will enable some explanation and prediction of the variation in mechanical and physical properties in Douglas-fir. It was found that Douglas-fir is stronger, stiffer and denser than the UK's most planted conifer, Sitka spruce. Wood adjacent to the pith (middle of tree) termed as juvenile was weaker, less stiff and less dense. Within-tree variation accounted for most of the variation for the key properties of strength, stiffness and density. It was possible to build models for some of these properties based on cambial age (ring number from the pith). Considering branches, it was found that within-tree variation in size, frequency, angle and status (alive or dead) were highly variable but it was possible to build empirical models to describe branch architecture for a typical tree. It was possible to measure the rate of swelling in oven dry Douglas-fir in the radial and tangential dimensions, but swelling of the longitudinal dimension was below the limit of detection for the apparatus. Heartwood area can be successfully predicted from the diameter of tree at a given point. It is hoped the information in this study will detail some characteristic Douglas-fir traits that may be deemed beneficial for the timber construction industry and allow understanding of its variability plus provide important models to use in helping to describe Great Britain's forest resource.

This study was performed in a sample population of Chilean forestry workers who carried out heavy manual operations: tree-felling, cross cutting, debranching and log-piling. Following medical and dental examinations these workers were studied in laboratories specially set up in their isolated habitats. Maximal oxygen uptake, body composition am anthropometric characteristics were measured. The physiological work load am the energy expenditure during actual work were assessed by measuring oxygen uptake and cardiac frequency.

Fast growing hybrids of Salix and Populus can be grown in a short rotation coppice (SRC) system to produce renewable energy. This PhD investigates the interactions between the environment and productivity, with a view to finding the key limiting factors to yield and the potential of these crops to fulfil UK renewable energy obligations, now and in the future. An empirical modelling technique, using partial least squares regression was developed to extrapolate actual field observations to a national scale. Genotype x age x environment interactions were studied to examine the key limiting factors to productivity. Modelled yields differed between genotypes, with mean annual aboveground biomass ranging from 4.9 to 10.7 oven dry tonnes (odt) per hectare for Populus trichocarpa x P. deltoides genotype ‘Beaupré’ and Salix triandra x S. viminalis genotype ‘Q83’, respectively. Variation in yield was primarily described by spring and summer precipitation, suggesting water availability is the key limiting factor to yield. Output from the model was up-scaled across the UK using a geographic information system (GIS), and scenarios were developed to better understand the role and impact of land use management and policy development on potential crop distribution. For example, to meet UK biomass and biofuel targets without compromising food security or ecosystem services, would require 5 % of grade 3 land, 56 % grade 4 land and 47 % of grade 5 land. This quantity of biomass would produce 7.5 M tonnes of biomass per annum and would theoretically generate 15.5 TWh yr-1 of electrical energy, displacing 3.3 M tonnes of oil – approximately 4% of current UK electricity demand. The South West and North West alone producing over a third of this figure (5.2 TWh yr-1). These results suggest that SRC has the potential to become a significant component of a mixed portfolio of renewables. Furthermore, climate change is predicted to have far reaching consequences on crop growth. Process-based models can help quantify these interactions and predict future productivity. Here we use ForestGrowth-SRC, a process-based model originally designed for high-forest species and parameterised for a coppice system. Climate change scenarios (UK Climate Projections) were run with the model to assess the impact of a changing climate on the growth and spatial distribution of SRC poplar. Results suggest ForestGrowth-SRC is capable of accurately simulating growth over a large spatial and temporal scale. However, pests and disease were found to significantly affect yield. In the absence of pests and disease, productivity could increase by 20 % nationwide by 2080 (under a medium emissions scenario), suggesting we will see a future increase in the value and production of these crops as feedstocks for heat, power and liquid transportation fuels