共查询到20条相似文献,搜索用时 546 毫秒
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Pot experiments are often performed to assess plant physiological traits and relationships among growth traits under controlled environments. However, the reliability of pot studies for predicting the growth and performance of trees in the field has rarely been rigorously assessed. We evaluated the suitability of pot experiments for predicting field performance, measured as shoot biomass production, by investigating determinants of growth in hybrid willows (Salix spp.) grown under various environmental conditions in the field, and by comparing the data with the results from a corresponding pot study. Biomass production in six hybrid willow clones, bred for use as bio-fuels, was assessed in three field trials located in central and southeastern Sweden throughout the first 3-year cutting cycle. The determinants of biomass productivity, measured as biomass allocation and nitrogen (N) economy, were identified in one of the field trials. Key traits for shoot biomass production in the field were total leaf area and total amount of N; plant N losses by shed leaves were only partly controlled by leaf-litter N concentration. These key traits were also obtained from the pot study and related to shoot biomass production and abscission-leaf N loss in the field. Total leaf area and total N pool of plants grown in pot experiments were good predictors of long-term biomass production in the field, whereas shoot biomass production, specific leaf area and tissue N concentration of pot-grown plants were less suitable as predictors of field performance. Relationships between the key traits and shoot biomass production were clone-specific, indicating the need for analysis of growth traits at the clone level if field performance of trees is to be evaluated based on data from pot studies. Nutrient loss components are important for tree performance in the long term and evaluations of nutrient loss characteristics at the individual-tree level should focus on nutrient pools lost rather than on nutrient concentrations in abscised plant parts. 相似文献
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《中国林业科技(英文版)》2009,(1)
At present biomass energy industry is in its infancy in China and it has a bright future. Biomass energy production used grain as raw materials has entered industrialization phase.Some key technologies of biomass energy industry are coming to mature.China has issued relevant industrial standards laws and regulations,and has provided support in finance,loan,tax,etc.But China's biomass energy industry is faced with many problems which need to be solved.For example,taking grain as raw materials is unsustain... 相似文献
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《Forest Ecology and Management》1997,91(1):17-45
Biomass fuels currently (1994) supply around 14% of the world's energy, but most of this is in the form of traditional fuelwood, residues and dung, which is often inefficient and can be environmentally detrimental. Biomass can supply heat and electricity, liquid and gaseous fuels. A number of developed countries derive a significant amount of their primary energy from biomass: USA 4%, Finland 18%, Sweden 16% and Austria 13%. Presently biomass energy supplies at least 2 EJ year−1 in Western Europe which is about 4% of primary energy (54 EJ). Estimates show a likely potential in Europe in 2050 of 9.0–13.5 EJ depending on land areas (10% of useable land, 33 Mha), yields (10–15 oven-dry tonnes (ODt) ha−1), and recoverable residues (25% of harvestable). This biomass contribution represents 17–30% of projected total energy requirements up to 2050. The relative contribution of biofuels in the future will depend on markets and incentives, on continuous research and development progress, and on environmental requirements. Land constraints are not considered significant because of the predicted surpluses in land and food, and the near balance in wood and wood products in Europe.There is considerable potential for the modernisation of biomass fuels to produce convenient energy carriers such as electricity, gases and transportation fuels, whilst continuing to provide for traditional uses of biomass; this modernisation of biomass and the industrial investment is already happening in many countries. When produced in an efficient and sustainable manner, biomass energy has numerous environmental and social benefits compared with fossil fuels. These include improved land management, job creation, use of surplus agricultural land in industrialised countries, provision of modern energy carriers to rural communities of developing countries, a reduction of CO2 levels, waste control, and nutrient recycling. Greater environmental and net energy benefits can be derived from perennial and woody energy cropping than from annual arable crops which are short-term alternative feedstocks for fuels. Agroforestry systems can play an important role in providing multiple benefits to growers and the community, besides energy. In order to ameliorate CO2 emissions, using biomass as a substitute for fossil fuels (complete replacement, co-firing, etc.) is more beneficial from social and economic perspectives than sequestering the carbon in forests.Case studies are presented for several developed countries and the constraints involved in modernising biomass energy along with the potential for turning them into entrepreneurial opportunities are discussed. It is concluded that the long term impacts of biomass programmes and projects depend mainly on ensuring income generation, environmental sustainability, flexibility and replicability, while taking account of local conditions and providing multiple benefits, which is an important attribute of agroforestry-type systems. Biomass for energy must be environmentally acceptable in order to ensure its widespread adoptions as a modern energy source. Implementation of biomass projects requires governmental policy initiatives that will internalise the external economic, social and environmental costs of conventional fuel sources so that biomass fuels can become competitive on a ‘level playing field’. 相似文献
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The use of forest biomass as a renewable energy source has received much attention as a response to climate change and the
increasing global demands for energy. Local availability and conversion into secondary energy carriers with a lower capital
investment shows more weights on its interests. The substitution of fossil fuel by biomass fuel can have a strong effect on
the mitigation of climate change through reducing greenhouse gases, which can be an important consideration for CDM projects
in Bangladesh. This study uses literature review to analyse the legal framework of carbon trading under CDM, CDM additionality,
CDM and bioenergy promotion, land availability and technology for biomass production, and sustainability of CDM projects in
Bangladesh. The barriers to CDM projects in Bangladesh are explained as well as measures for promoting biomass production.
Biomass and bioenergy-based CDM projects can be attractive and support sustainable development in Bangladesh. The study suggests
capacity building and policy changes needed in order to comply with CDM modalities. The study can be useful to the climate
change mitigation and development policy makers in Bangladesh. 相似文献
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生物质制乙醇是解决当前世界能源短缺的重要途径。当前生物质制乙醇在国内外无法大规模投入生产的主要原因是成本过高。选取优质的生物质材料和高效的预处理方法可以有效解决这一问题。以6个泡桐品种为试验材料,采用稀硫酸、氢氧化钠、微波-氢氧化钠3种方法进行预处理,对泡桐纤维素含量和酶解后还原糖产量进行测定,探讨不同预处理方法对纤维素含量和还原糖产量的影响。结果表明:以微波-氢氧化钠法预处理毛泡桐品种效果良好,处理后纤维素含量达84.82%,较预处理前提升了38.01%;半纤维素和木质素分别降低了21.23%和6.65%;还原糖产量较高,为471.38 mg/g。该研究可为生物质制乙醇高效预处理方法和优质生物质材料的选择提供参考。 相似文献
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《Journal of Sustainable Forestry》2013,32(3):93-103
The accident at the Chernobyl nuclear power plant in 1986 led to a significant increase of radionuclide content in the eastern part of central Sweden. Radioactive cesium (Cs-134 and Cs-137) have accumulated in the soil, waters and living organisms. In agriculture, farmers are looking for alternative crops also in areas with a high radioactive content. Biomass plantations for energy are potential candidates for such soils provided the cycling of radionuclides can be controlled. Nothing IS known so far about the behaviour of cesium in energy forest production systems. The ability to take up cesium and the distribution of Cs-134 and Cs-137 within plants were investigated in a selected fast-mowing willow clone. kesium-contaminatid soil was used as substrate for apot experiment with cutting-derived plants of Salix viminalis. The total plant uptake of Cs-134 + Cs-137 was approximately 0.2% of the cesium present in the soil substrate. Almost 90% of the assimilated cesium was found allocated to the roots. The total amount of cesium in the plants increased over time. 相似文献