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The context of famine in Turkana has changed in recent years as the role played by livestock raiding in contributing to famine has increased. External responses to famine in Turkana have largely been drought driven, for example, food assistance and livestock restocking programmes, which have failed to meet the real needs of herders. The role of armed conflict in the form of raiding has been overlooked as a common feature of societies facing famine and food insecurity.The traditional livelihood-enhancing functions of livestock raiding are contrasted with the more predatory forms common today. The direct impact of raiding on livelihood security can be devastating, while the threat of raids and measures taken to cope with this uncertainty undermine herders' livelihood strategies. Self-imposed restrictions on mobility negatively affect the vegetation of both grazed and ungrazed pastures and restrict the available survival strategies. Predatory raiding leads to a collapse in the moral economy. Some implications of this for relief and development policy are considered, including approaches to conflict resolution. 相似文献
63.
Rare royal families in honeybees, Apis mellifera 总被引:1,自引:0,他引:1
Moritz RF Lattorff HM Neumann P Kraus FB Radloff SE Hepburn HR 《Die Naturwissenschaften》2005,92(10):488-491
The queen is the dominant female in the honeybee colony, Apis mellifera, and controls reproduction. Queen larvae are selected by the workers and are fed a special diet (royal jelly), which determines
caste. Because queens mate with many males a large number of subfamilies coexist in the colony. As a consequence, there is
a considerable potential for conflict among the subfamilies over queen rearing. Here we show that honeybee queens are not
reared at random but are preferentially reared from rare “royal” subfamilies, which have extremely low frequencies in the
colony's worker force but a high frequency in the queens reared. 相似文献
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Diffusion experiments in compacted bentonite have been carried out in situ using the borehole laboratory CHEMLAB. The "ordinary" anion iodide and the redox-sensitive pertechnetate ion have been investigated. In spite of strongly reducing groundwater conditions, technetium was found to diffuse mostly unreduced as TcO4-, although in some spots in the compacted clay, the activity was significantly higher, which may be explained by reduction of some TcO4- by iron-containing minerals in the bentonite. The measured concentration profiles in the clay cannot be accommodated by assuming one single diffusion process. The experimental data are modeled assuming two diffusion paths, intralamellar diffusion and diffusion in external water. The apparent diffusivity for the intralamellar diffusion was found to be 8.6 x 10(-11) m2 s(-1) for iodide with a capacity factor of 0.1, while the apparent diffusivity for the diffusion in external water was found to be 5 x 10(-14) m2 s(-1) with alpha=2.26. The corresponding values for Tc were found to be Da= 6 x 10(-11) m2 s(-1), alpha=0.1 and Da= 1 x 10(-13) m2 s(-1), alpha=0.46, respectively. The diffusion constants and capacity factors obtained in this study are in accordance with data from laboratory experiments. 相似文献
67.
Thomas Fellmann Peter Witzke Franz Weiss Benjamin Van Doorslaer Dusan Drabik Ingo Huck Guna Salputra Torbjörn Jansson Adrian Leip 《Mitigation and Adaptation Strategies for Global Change》2018,23(3):451-468
Taking the European Union (EU) as a case study, we simulate the application of non-uniform national mitigation targets to achieve a sectoral reduction in agricultural non-carbon dioxide (CO2) greenhouse gas (GHG) emissions. Scenario results show substantial impacts on EU agricultural production, in particular, the livestock sector. Significant increases in imports and decreases in exports result in rather moderate domestic consumption impacts but induce production increases in non-EU countries that are associated with considerable emission leakage effects. The results underline four major challenges for the general integration of agriculture into national and global climate change mitigation policy frameworks and strategies, as they strengthen requests for (1) a targeted but flexible implementation of mitigation obligations at national and global level and (2) the need for a wider consideration of technological mitigation options. The results also indicate that a globally effective reduction in agricultural emissions requires (3) multilateral commitments for agriculture to limit emission leakage and may have to (4) consider options that tackle the reduction in GHG emissions from the consumption side. 相似文献
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Physical and biological disturbances are ecological processes affecting patterns in biodiversity at a range of scales in a variety of terrestrial and aquatic systems. Theoretical and empirical evidence suggest that effects of disturbance on diversity differ qualitatively and quantitatively, depending on levels of productivity (e.g., the dynamic equilibrium model). In this study we contrasted the interactive effects between physical disturbance and productivity to those between biological disturbance and productivity. Furthermore, to evaluate how these effects varied among different components of marine hard-substratum assemblages, analyses were done separately on algal and invertebrate richness, as well as richness of the whole assemblage. Physical disturbance (wave action) was simulated at five distinct frequencies, while biological disturbance (grazing periwinkles) was manipulated as present or absent, and productivity was manipulated as high or ambient. Uni- and multivariate analyses both showed significant effects of physical disturbance and interactive effects between biological disturbance and productivity on the composition of assemblages and total species richness. Algal richness was significantly affected by productivity and biological disturbance, whereas invertebrate richness was affected by physical disturbance only. Thus, we show, for the first time, that biological disturbance and physical disturbance interact differently with productivity, because these two types of disturbances affect different components of assemblages. These patterns might be explained by differences in the distribution (i.e., press vs. pulse) and degree of selectivity between disturbances. Because different types of disturbance can affect different components of assemblages, general ecological models will benefit from using natural diverse communities, and studies concerned with particular subsets of assemblages may be misleading. In conclusion, this study shows that the outcome of experiments on effects of disturbance and productivity on diversity is greatly influenced by the composition of the assemblage under study, as well as on the type of disturbance that is used as an experimental treatment. 相似文献
70.
Robin Tennant-Wood 《Local Environment》2013,18(6):527-539
In areas where rivers have been altered and regulated through dams, the effect on wetland ecosystems can lead to 'wastage' of the land as natural systems are destroyed. In response to the effects of streamflow regulation on a wetland near the city of Albury, on the Murray River, the development of the Wonga Wetlands and associated site rehabilitation addresses two key issues: wasteland and waste water. A Community Advisory Committee has been actively and directly involved in the project, initiated and implemented by the Albury City Council, to restore an area of original wetland into a community ecological resource that utilises 100% of the domestic, commercial and industrial urban 'waste' water from the city's water treatment plant. This project represents a significant direction in the way communities and local governments approach resource recovery. This paper analyses the Wonga Wetlands project from the perspective of sustainable management of waste in terms of water resources and presents it as a model for community-based environmental application and long-term resource sustainability. 相似文献