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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

AN INVESTIGATION INTO THE CAUSES AND PREVENTION OF FROST HEAVING OF FOREST TREE SEEDLINGS

Heidmann, L. J. January 1974 (has links)
No description available.
52

The Fifth Pathway to Forest Transition in the Andes: Modeling Factors That Influence Smallholder Tree Planting in Mocoties, Venezuela

Ponnambalam, Kumary 19 March 2014 (has links)
Smallholder tree planting is a pathway recognized within Forest Transition Theory (FTT), but its contributing factors are not fully explored at the household level. This study examines the effect of socio-economic and biophysical characteristics, access to extension services, land tenure, labour availability, and attitudes toward tree cover on smallholder planting and willingness to plant for environmental and economic purposes at the household level. Data was collected from 146 households in Mocoties, Merida, Venezuela. Logistic models revealed that area of property, area of productive land, presence of natural sources of water, gender of respondent, number of generations that have farmed the property, income, percent income from farming activities, land title, harvest rights, labour availability and attitudes toward tree cover have significant influence on smallholder’s tree planting and willingness to plant. Future research needs to focus on factors that affect environmentally motivated smallholder tree planting where fewer significant variables were found.
53

The Fifth Pathway to Forest Transition in the Andes: Modeling Factors That Influence Smallholder Tree Planting in Mocoties, Venezuela

Ponnambalam, Kumary 19 March 2014 (has links)
Smallholder tree planting is a pathway recognized within Forest Transition Theory (FTT), but its contributing factors are not fully explored at the household level. This study examines the effect of socio-economic and biophysical characteristics, access to extension services, land tenure, labour availability, and attitudes toward tree cover on smallholder planting and willingness to plant for environmental and economic purposes at the household level. Data was collected from 146 households in Mocoties, Merida, Venezuela. Logistic models revealed that area of property, area of productive land, presence of natural sources of water, gender of respondent, number of generations that have farmed the property, income, percent income from farming activities, land title, harvest rights, labour availability and attitudes toward tree cover have significant influence on smallholder’s tree planting and willingness to plant. Future research needs to focus on factors that affect environmentally motivated smallholder tree planting where fewer significant variables were found.
54

Effect of forest structure on the understory light environment and growth potential of oak seedlings in a closed canopy riparian forest

Ostrom, Bradford J., Loewenstein, Edward F. January 2005 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.
55

Growth and survival of eleven planted tree species on a reclaimed surface mine in West Virginia

Emerson, Paul January 2008 (has links)
Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xi, 84 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 77-84).
56

Seed and seedling ecology in the early stages of rainforest restoration /

Doust, Susan Jillian. January 2004 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.
57

An??lise multitemporal do comportamento estrutural e espectral da regenera????o do cerrado sensu-stricto

Costa-Pereira, Priscilla de Souza January 2009 (has links)
Submitted by Gustavo Gomes (gustavolascasas@gmail.com) on 2013-09-10T12:47:49Z No. of bitstreams: 2 An??lise multitemporal do comportamento estrutural e espectral.pdf: 5588827 bytes, checksum: 87e23a99e66df453056ebb387f9ea8f7 (MD5) license_rdf: 23599 bytes, checksum: 9e2b7f6edbd693264102b96ece20428a (MD5) / Approved for entry into archive by Roger Guedes (roger.guedes@fjp.mg.gov.br) on 2013-09-10T14:28:33Z (GMT) No. of bitstreams: 2 An??lise multitemporal do comportamento estrutural e espectral.pdf: 5588827 bytes, checksum: 87e23a99e66df453056ebb387f9ea8f7 (MD5) license_rdf: 23599 bytes, checksum: 9e2b7f6edbd693264102b96ece20428a (MD5) / Made available in DSpace on 2013-09-10T14:28:33Z (GMT). No. of bitstreams: 2 An??lise multitemporal do comportamento estrutural e espectral.pdf: 5588827 bytes, checksum: 87e23a99e66df453056ebb387f9ea8f7 (MD5) license_rdf: 23599 bytes, checksum: 9e2b7f6edbd693264102b96ece20428a (MD5) Previous issue date: 2009 / Funda????o Jo??o Pinheiro / O Cerrado ?? um complexo vegetacional rico em biodiversidade, com alto grau de endemismo. Contudo, est?? seriamente amea??ado pela expans??o do agroneg??cio e crescentes monoculturas de eucalipto. Pesquisas sobre a regenera????o do Cerrado s??o fundamentais no entendimento da din??mica da vegeta????o e nos estudos de conserva????o. O objetivo desta pesquisa ?? caracterizar a idade da vegeta????o do cerrado sensu-stricto atrav??s da an??lise de uma longa sequ??ncia de imagens TM/Landsat-5 (I984 a 2007), identificando rela????es entre a estrutura da vegeta????o e o comportamento espectral. O Parque Estadual Veredas do Perua??u (PEVP), escolhido como ??rea de estudo, foi ocupado por planta????es de eucalipto at?? 1994 e hoje cont??m extensas ??reas de cerrado sensu-str:icto em processo de regenera????o. O hist??rico de degrada????o do PEVP foi obtido atrav??s da subtra????o de imagens NDVI em pares entre 1984 e 2007. O m??todo de "parcelas" foi adotado para medir as vari??veis estruturais da vegeta????o. Em toda a ??rea amostrada (9.400 m2) foram mensurados e identificados 2.030 indiv??duos lenhosos com CAP maior ou igual a 10 cm, agrupados em 22 fam??lias bot??nicas contendo 45 g??neros e 53 esp??cies. Pol??gonos de 2x2 pixels, representando as 47 parcelas mensuradas no campo foram utilizados para extrair o valor de reflect??ncia das imagens e, assim, caracterizar a resposta espectral da regenera????o da vegeta????o em cada data estudada e analisar as rela????es estat??sticas entre as vari??veis estruturais e espectrais. Apesar dos baixos coeficientes de correla????o observados entre as vari??veis espectrais.e estruturais, um modelo matem??tico multivariado de estimativa da idade da vegeta????o foi gerado a partir de regress??o m??ltipla explicando 61 % da varia????o da idade. A sequ??ncia de 18 imagens Landsat serviu para caracterizar a din??mica do comportamento espectral da regenera????o de cerrado e permitiu estimar o tempo aproximado que a vegeta????o de cerrado dessa regi??o necessita para alcan??ar um aspecto semelhante ao cerrado sem degrada????o recente. Al??m desses resultados, um levantamento fitossociol??gico das parcelas permitiu uma caracteriza????o flor??stica lenhosa dessa regi??o de cerrado comparando os valores obtidos com outras ??reas de condi????o ed??ficas semelhantes. / Cerrado is a biologically rich vegetation complex, with a high degree of endemism. It is, however, seriously threatened by expansion of agribusiness and growing monocultures of eucalyptus. Research on Cerrado regrowth is crucial for understanding the dynamics of vegetation and for studies of conservation. The purpose of this study is to characterize the age of cerrado sensu-stricto vegetation through the analysis of a long sequence of TM/Landsat-5 images (1984 to 2007), identifying relationships between the structure of vegetation and its spectral behavior. The Veredas do Peruac??u State Park (VPSP), chosen as the study area, was occupied by eucalyptus plantations until 1994 and now contains large areas of savanna in the process of regeneration. The history of degradation of the VPSP was obtained by subtracting NDVI images in pairs between 1984 and 2007. The ???plot??? methods was adopted to measure the structure of the vegetation. Throughout the area sampled (9.400m2) 2.030 woody individuals were identified and measured with CAP greater or equal to 10cm grouped in 22 botanical families containing 45 genus and 53 species. Polygons of 2??2 pixels, representing all 47 plots measured in the field, were used to extract reflectance values from the images and thus characterize the spectral behavior of the regeneration of vegetation over time and analyze the statistical relationship between the spectral and structural variables. Although generally low correlation coefficients were observed between the spectral and structural variables, a valid multivariate mathematical model to estimate the age of cerrado vegetation was generated through multiple regression explaining 61% of the age variation. The sequence of 18 Landsat images was used to characterize the dinamics of the spectral behavior of regenerating cerrado and estimate the time necessary for cerrado vegetation of that region to regain a spectral aspect similar to non-degraded cerrado. Additionally, a phytosociological survey made it possible to characterize the floristic composition of woody plants and compare these values with other areas having the same edaphic conditions. / Meio ambiente
58

Trends in forestry mechanization and concepts for containerized seeding in New Zealand

Page, Arthur Ian January 1971 (has links)
Review of the literature on the future of wood resulted in the conclusion that long term future demand will be for large quantities of cheap fibre. There is likely to be a reduction in emphasis on the form and dimension of individual trees. Mechanization and automation are defined and the relative importance of tree establishment within the total forest industry noted. Some general principles of forest mechanization are proposed and discussed. The New Zealand potentials for wood fibre production and forest mechanization are analysed. Reforestation history of radiata pine (Pinus radiata, D.Don.) in New Zealand is briefly described, and the basis for, and problems with, bare-root planting are discussed. An alternative tree establishment system, involving the precision setting of a bullet-like container enclosing a seed, is proposed. The case for this theoretical system is argued on the basis of its potential biological equality with bare-root planting, which the author considers to be sufficiently promising to be worthy of field investigation, and its suitability to total mechanization. Some possible costs of the system are calculated and potential benefits are postulated. It is concluded that the concept is worthy of careful field study in New Zealand. / Forestry, Faculty of / Graduate
59

Worker participation in the reforestation labour force in British Columbia

Davis Case, D’Arcy January 1985 (has links)
One response to problems of low productivity and decreased job satisfaction in the workplace has been the institution of worker participation in decision-making. Evaluations of worker participation programs generally have shown them to be beneficial in terms of both job satisfaction and increased productivity. In British Columbia, we have a unique example of worker participation in the contract reforestation labour force which can be seen as an informally structured, semi-participative worker participation group. In light of theory on worker participation, this study examines two reforestation crews, one a contract crew and one a non-contract crew, to compare worker participation in the areas of technology, division of labour and organizational structure. Worker participation has been found by most researchers to be cost effective. This study compared cost differences between the two labour groups, and although it did not generate conclusive evidence of the relative cost efficiency of the contract group, it is suggested that the British Columbia Ministry of Forests Section 88 final planting cost data is not a reliable basis for determination of relative cost efficiencies. However, the perspectives of those working in reforestation, and an economic analysis of one case study suggest that the contract group is more cost effective. But changes in the contract work force are occurring. These changes can influence the worker participation evident in contract planting, and hence the cost effectiveness of contract planting. In order to capitalize on those attributes in the worker participation model which have value to the forest manager in the goal of forest renewal, the concept of stewardship, a long term contract which begins with planting and carries through to the "free to grow" stage, is one of the alternatives proposed for future reforestation contracts. / Forestry, Faculty of / Graduate
60

Natural revegetation of disturbed sites in British Columbia

Errington, John Charles January 1975 (has links)
Factors affecting the natural revegetation of areas disturbed by airborne emissions were studied at the Anyox smelter on the northern coast of British Columbia. Revegetation of areas where vegetation and soil were removed by industry were studied on mine waste dumps on Vancouver Island, on mine wastes in the West Kootenays, and on abandoned logging roads on Vancouver Island and near Lumby. At Anyox, much of the direct evidence of fume damage was eradicated by a fire in 1942, which occurred eight years after smelting operations ceased. This fire encompassed a five-mile radius surrounding the smelter. Tree-ring analysis on surviving western hemlock trees, extending from the edge of the fire to the head of Alice Arm, showed a strong relationship between the tonnage of ore smelted and the radial increment. Tree growth was initially depressed when smelting began in 1914 and remained low until smelter operations ceased. At this time the growth dramatically increased, but by 1970 the annual radial increment had returned to a slow rate similar to before smelting operations began. Western hemlock was much less susceptible to fume damage than western red cedar. Although total fume kill occurred on western red cedar as far south as the Nass River, north to the head of Hastings Arm and East to the head of Alice Arm, total kill on hemlock took place within a few miles of the smelter. Fume damage was the heaviest near the smelter and near the head of Alice Arm where the topography confined the fumes, rendering them more effective. Within the area affected by the 1942 fire, revegetation was slow near the smelter and was more rapid near the mature vegetation. Seeds which are easily dispersed by light wind, were responsible for the majority of colonizing species many of which were found rarely in the surrounding unburned vegetation. On logging roads and mine waste materials, seed source availability appeared to be the major factor in determining the colonizing species. Light wind-blown seeds were the initial colonizers on coastal logging roads, and adjacent vegetation supplied the seed source for the interior logging roads. The establishment of salal through vegetative means was' observed to occur on coastal logging roads. Species with the ability to fix nitrogen, with the exception of alder, played a minor role in natural revegetation of most areas. Slow revegetation of large-scale disturbances was attributed partly to the lack of adequate seed. The most common cause of slow revegetation in most areas was moisture deficiency. Moisture availability on mine wastes at Cumberland appeared to be determined by slope, aspect, color, shading and mound height. On logging road surfaces, in both Lumby and coastal areas, a reduction in plant growth on steeper slopes was attributed to reduced moisture. Wind exposure was found to be the most important factor governing revegetation of mine wastes in the West Kootenays. Coarse textured material was related to a lower percentage cover of vegetation on the surface of coastal logging roads. Uniformly coarse textured material on the waste dumps in the West Kootenays precluded any significant statistical relationships. Coarse textured materials, nevertheless, had a general inhibitory effect on the rate of revegetation of many of the mine waste dumps. Steep unstable slopes were a major factor which prevented revegetation of West Kootenay mine wastes and on the upslope of road cuts. The scale of disturbance was found to magnify or obscure many of the factors important to successful plant colonization. The chemical composition of waste material, although studied only peripherally, did not appear to be a major factor in determining the revegetation of disturbed areas at the sites studied. Low pH values, which are often taken as a barometer of mine waste toxicity, occurred rarely. In many instances, high pH values may have prevented the successful invasion of acid-loving species. In applied reclamation procedures, it is mandatory that objectives for future land use be incorporated into planning, along with the anticipation of inhibiting factors. If no conditions are left which prevent plant growth, then reclamation will be straightforward and land use goals will be more easily satisfied. / Forestry, Faculty of / Graduate

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