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Boswellia papyrifera (Del.) Hochst is a multipurpose deciduous tree species with high economic, cultural and environmental values. Frankincense from this tree species is a traded commodity used in the pharmaceutical, food, cosmetic and chemical industries, for clerical services in different religions, and as a fragrance during coffee ceremonies in Ethiopia. However, the resource has been declining due to unsustainable management, which includes shifting to crop cultivation, free grazing and indiscriminate cutting of leaves for livestock feeding, and overtapping for frankincense. This study aims at: a) assessing the effects of leaf lopping for fodder, tapping for frankincense, and free grazing on the biophysical state of Boswellia papyrifera forests of Ethiopia, b) assessing the stocks of biomass and soil organic carbon in Boswellia papyrifera forests, c) evaluating the trade-offs between conservation, production forestry, and shifting to crop cultivation, d) assessing rural households’ demand for conserving the forest, and e) identifying the role of frankincense forests on rural livelihood and poverty reduction. The dissertation is a multidisciplinary piece of work based mainly on primary data from plot level experiments and a household survey conducted in five villages with Boswellia papyrifera forests in Tigray, northern Ethiopia. For analysing these biophysical and socio-economic data, a number of statistical and econometric models are applied, which include: multilevel linear mixed model, the standard allometric model, the model of environmental cost benefit analysis, the double-bound dichotomous contingent valuation method, and standard impact assessment parametric and non-parametric econometric models. We found that leaf cutting caused significant declines in frankincense yield, and production of inflorescence and fruits. Tapping showed a significant positive impact on frankincense yield, but there was no evidence of a significant difference between tapped and untapped trees in terms of flowering and fruiting. Some environmental variables like altitude, soil depth and nutrient content also significantly affect tree productivity. Interestingly frankincense yield, flower and fruit production significantly differ in relation to the bark colour that would be used as an indicator of tree fitness. The allometric model AGB = 0.061(DBH) 2.353 predicts the above ground biomass carbon in Boswellia papyrifera forest with an average bias of less than 2%. The stored carbon in Boswellia papyrifera forests was about 44 Mg ha-1 of which nearly 78% was accounted by soil organic carbon and fenced plots had more concentrations of carbon and nutrients in the soil than unfenced plots. Given the economic and ecological importance of this species and the limited data on biomass and carbon stock especially in dry forests of Africa, the findings are useful for biomass and carbon stock estimation, and for assessing the implications of land use change on carbon emissions. Moreover, it is also important for validating existing generalized allometric models, which mostly lack evidence from Africa’s dry forest. The cost benefit analysis assesses the economic benefits and costs of six frankincense forest management options that range from conservation in the form of exclosure to the business as usual scenario that involves free grazing, leaf lopping and intensive frankincense tapping. The Net Present Values of almost all the forestry options are negative if the benefits from carbon and nutrient storage services are excluded indicating that direct benefits from frankincense forests are less than the benefits from the competing land use. Moreover, as shifting cultivation is the competing land use in the study area, estimates of the opportunity costs of reducing emissions from deforestation and forest degradation (REDD) specific to the forest were also provided. Accordingly, pure conservation of the forest could result in emission reduction of about 142 tons of CO2 per hectare at an opportunity cost of about 33 USD per ton of CO2 emission reduction. About 80% of this opportunity cost is incurred by rural people in the form of forgone net benefits from not converting the forest to cropland through shifting cultivation. The contingent valuation study aims at assessing local evidence on whether any conservation intervention will be welcomed by rural people in the Boswellia forest areas. Accordingly, the study assessed the rural households’ willingness to pay and willingness to contribute labour for Boswellia papyrifera forest conservation. We found that next to the bid level, willingness to pay is influenced most by income and education, and willingness to contribute labour is significantly affected by size of family labour and gender of the household head. A household is willing to pay at least about 5 USD per year or contribute almost one week of free labour per year, which amounts to close to 7 USD valued at per capita daily income of the households. The potential local demand for conservation of Boswellia papyrifera forest could be mobilized effectively with complementary policy interventions aimed at sustainable use and poverty reduction. Recently there is a considerable debate on the role of non-timber forest products on poverty alleviation. The study on the impact of frankincense membership on rural income and poverty contributes to the empirical literature on the role of organized access to a traded non-timber forest product on rural livelihood and poverty reduction. In the past, rural households in northern Ethiopia had no access to frankincense production and trading. With recent developments in the region, rural households are getting access to the harvesting of frankincense through organizing cooperatives. We analysed the income and poverty effects of rural frankincense cooperative firms and the results indicate that both membership as a binary variable and amount of households’ investment on shares in the cooperative firms have significant positive welfare impacts in terms of increasing householdincome and reducing rural poverty. The negative impact of leaf looping on the tree’s capacity to produce frankincense, fruits and flowers as well as the negative net present values of all the forestry alternative management options indicate that the forest is in a very high risk of continuous degradation and perpetuation of what is called “a tragedy of the commons”. Thus, conservation and sustainable management practices should be in place to increase the resources’ competitiveness and hence avoid its degradation. This could be possible through interventions that can make developments in alternative livestock feed productions, through creating favorable conditions for the development of businesses that can add value to the frankincense, which is now exported as a raw material, and with the introduction of the other ecosystem service benefits of the resource like development of bee keeping and ecotourism. Moreover, the participation of rural communities both in the conservation and sharing of benefits from the resource are very crucial in future conservation and management interventions as it has been confirmed from the results of the contingent valuation on rural households demand for conservation as well as the results from the impact evaluation. However, further research is required on assessing the resource base at a wider spatial scale, on whether bark color of the tree is a genetic or phenotypic phenomenon affecting tree productivity, and also on the problems associated with legal and institutional frameworks in the use and management of Boswellia papyrifera forests in Ethiopia.

Academic collection --- 582.752.2 --- 630*611 --- Burseraceae. Balsam tree. Aucoumea. Dacryodes --- Sustained yield; progressive yield --- Theses --- 630*611 Sustained yield; progressive yield --- 582.752.2 Burseraceae. Balsam tree. Aucoumea. Dacryodes

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Differential geometry. Global analysis --- Geometry, Differential. --- 514.752 --- Geometry, Differential --- #TELE:MI2 --- Differential geometry --- Differential geometry in Euclidean and pseudo-Euclidean spaces --- 514.752 Differential geometry in Euclidean and pseudo-Euclidean spaces --- Géometrie différentielle --- Géometrie différentielle --- Courbes --- Surfaces (mathématiques)

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The study of curves and surfaces forms an important part of classical differential geometry. Differential Geometry of Curves and Surfaces: A Concise Guide presents traditional material in this field along with important ideas of Riemannian geometry. The reader is introduced to curves, then to surfaces, and finally to more complex topics. Standard theoretical material is combined with more difficult theorems and complex problems, while maintaining a clear distinction between the two levels. Key topics and features: * Covers central concepts including curves, surfaces, geodesics, and intrinsic geometry * Substantive material on the Aleksandrov global angle comparison theorem, which the author generalized for Riemannian manifolds (a result now known as the celebrated Toponogov Comparison Theorem, one of the cornerstones of modern Riemannian geometry) * Contains many nontrivial and original problems, some with hints and solutions This rigorous exposition, with well-motivated topics, is ideal for advanced undergraduate and first-year graduate students seeking to enter the fascinating world of geometry.

Curves on surfaces. --- Geometry, Differential. --- Differential geometry --- Surfaces, Curves on --- Curves on surfaces --- Geometry, Differential --- 514.752 --- 514.752 Differential geometry in Euclidean and pseudo-Euclidean spaces --- Differential geometry in Euclidean and pseudo-Euclidean spaces --- Global differential geometry. --- Differential Geometry. --- Differential geometry.

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Values --- Social values --- -Social values --- -Values --- -#SBIB:324H30 --- 316.752 --- #SBIB:316.7C122 --- Axiology --- Worth --- Aesthetics --- Knowledge, Theory of --- Metaphysics --- Psychology --- Ethics --- Politieke cultuur --- Waarden --(sociologie) --- Cultuursociologie: overtuigingen, waarden en houdingen --- 316.752 Waarden --(sociologie) --- #SBIB:324H30 --- Values - Europe --- Social values - North America --- Values - North America --- Social values - Europe --- Social values.

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Television authorship --- Television programs --- Television broadcasting --- Plots, themes, etc. --- Social aspects --- -Television programs --- -316.752 --- #SBIB:309H1522 --- 316.3 --- Programs, Television --- Shows, Television --- Television shows --- TV shows --- Electronic program guides (Television) --- Television scripts --- Telecasting --- Television --- Television industry --- Broadcasting --- Mass media --- Television writing --- Authorship --- -Plots, themes, etc --- Waarden --(sociologie) --- Radio- en/of televisieprogramma’s met een ideologische en spiegelfunctie --- Sociale structuur --(sociologie) --- Television authorship. --- 316.3 Sociale structuur --(sociologie) --- 316.752 Waarden --(sociologie) --- 316.752 --- Plots, themes, etc --- Television programs - France - Plots, themes, etc. --- Television broadcasting - Social aspects - France.