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541.
气候对河南省小麦产量的影响及其变化研究 总被引:21,自引:1,他引:21
河南省位于亚热带与温带的气候过渡带 ,小麦产量对气候变化非常敏感 ,气候对小麦产量影响的南北过渡性很明显。文中用正交多项式的方法分离小麦产量 ;用积分回归的方法分析气候对小麦产量的影响。在此基础上 ,首先根据降水量、温度和日照时数对小麦产量影响的区域分布 ,分别把河南省分为4个降水量影响区、4个温度影响区、5个日照影响区 ;然后 ,采用滑动积分回归的方法 ,分别分析了亚热带和温带3个影响因子对小麦产量影响的变化 ;最后 ,讨论了未来气候变化的可能影响。 相似文献
542.
Soil carbon pool in China and its global significance 总被引:19,自引:0,他引:19
SoilcarbonpoolinChinaanditsglobalsignificance¥FangJingyun,LiuGuohua,XuSongling(ResearchCenterforEco-EnvironmentalScience,Chin... 相似文献
543.
Venema Henry D. Schiller Eric J. Bass Brad 《Mitigation and Adaptation Strategies for Global Change》1996,1(2):139-165
The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change
and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought.
Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and
ecological relationships that define the control over the means of production and how people interact with their environment.
These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias
in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations
to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on
external inputs which strengthens the relationships introduced during the colonial period.
A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability
has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests
that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions,
this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty.
A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction
of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption
cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry
projects to redress the primary effects of desertification. 相似文献
544.
Michaelowa Axel Fages Emmanuel 《Mitigation and Adaptation Strategies for Global Change》1999,4(2):167-185
The Kyoto Protocol created the Clean Development Mechanism (CDM) to allow industrial countries to reach part of their greenhouse gas (GHG) emission reduction through projects in developing countries. To calculate the achieved emission reduction a reference scenario has to be developed – the baseline. Despite efforts to develop realistic baselines, a certain degree of uncertainty regarding actual reductions will be inevitable. It is therefore necessary to compare the costs (including transaction costs) of developing a baseline against the informational benefit it can be expected to produce. While project-related baselines are already being applied, the proponents of country-related baselines have still to show the applicability of their approach for the CDM. The possibility of quantifying indirect effects and considering market distortions and subsidies through aggregation in the country-related baselines is weighed up by the manipulability and uncertainty of the assumptions required in such a baseline. Thus project-specific baselines are recommended. In cases of severely distorted markets undergoing liberalization or subsidy phase-out, a country-related baseline can be helpful. Sectoral or programme baselines would be suited to large-scale energy and sequestration projects. Moreover it has to be considered whether emission reductions are generally achieved in the context of relocation or done in the context of global emitting capacity expansion. 相似文献
545.
Impact of Climate Change on Possible Scenarios for Egyptian Agriculture in the Future 总被引:1,自引:0,他引:1
El-Shaer H. M. Rosenzweig C. Iglesias A. Eid M. H. Hillel D. 《Mitigation and Adaptation Strategies for Global Change》1997,1(3):233-250
If no timely measures are taken to adapt Egyptian agriculture to possible climate warming, the effects may be negative and
serious. Egypt appears to be particularly vulnerable to climate change because of its dependence on the Nile River as the
primary water source, its large traditional agricultural base, and its long coastline, already undergoing both intensifying
development and erosion. A simulation study characterized potential yield and water use efficiency decreases on two reference
crops in the main agricultural regions with possible future climatic variation, even when the beneficial effects of increased
CO2 were taken into account. On-farm adaptation techniques which imply no additional cost to the agricultural system, did not
compensate for the yield losses with the warmer climate or improve the crop water-use efficiency. Economic adjustments such
as the improvement of the overall water-use efficiency of the agricultural system, soil drainage and conservation, land management,
and crop alternatives are essential. If appropriate measures are taken, negative effects of climate change in agricultural
production and other major resource sectors (water and land) may be lessened.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
546.
钾素Q/I特性是表征土壤钾素状况的一个重要指标,它能同时度量土壤钾素的强度和容量.本文研究了广东不同质地水稻土Q/I特性与大田钾肥施用技术的关系.结果表明:(1)不同质地土壤的Q/1曲线差异明显,砂土类曲线较平缓.粘土类曲线较陡。(2)PBCk与土壤粘粒含量呈极显著正相关(r=0.653).(3)-△K0与作物相对百分产量呈极显著正相关(r=0.873),可作为预测当季作物需钾量的参数.(4)AR_e ̄k与土壤粘粒含量呈显著负相关(r=-0.520),AR_e ̄k的大小可作为钾肥合理分配的依据. 相似文献
547.
Optimum Nitrogen Use and Reduced Nitrogen Loss for Production of Rice and Wheat in the Yangtse Delta Region 总被引:1,自引:0,他引:1
A long-term field and lysimeter experiment under different amount of fertilizer-N application was conducted to explore the optimal N application rates for a high productive rice–wheat system and less N leaching loss in the Yangtse Delta region. In this region excessive applications of N fertilizer for the rice–wheat production has resulted in reduced N recovery rates and environment pollution. Initial results of the field experiments showed that the optimal N application rate increased with the yield. On the two major paddy soils (Hydromorphic paddy soil and Gleyed paddy soil) of the region, the optimal N application rate was 225–270 kg N hm–2 for rice and 180–225 kg N hm–2 for wheat, separately. This has resulted in the highest number of effective ears and Spikelets per unit area, and hence high yield. Nitrogen leaching in the form of NO
3
–
-N occurs mainly in the wheat-growing season and in the ponding and seedling periods of the paddy field. Its concentration in the leachate increased with the N application rate in the lysimeter experiment. When the application rate reached 225 kg N hm–2, the concentration rose to 5.4–21.3 mgN l–1 in the leachate during the wheat-growing season. About 60% of the leachate samples determined contained NO
3
–
-N beyond the criterion (NO
3
–
-N 10 mg l–1) for N pollution. In the field experiment, when the N application rate was in the range of 270–315 kg hm–2, the NO
3
–
-N concentration in the leachate during the wheat-growing season ranged from 1.9 to 11.0 mg l–1. About 20% of the leachate samples reached close to, and 10% exceeded, the criterion for N pollution. Long-term accumulation of NO
3
–
-N from leaching will no doubt constitute a potential risk of N contamination of the groundwater in the Yangtse Delta Region. 相似文献
548.
549.
减少农业甲烷排放的技术选择 总被引:1,自引:1,他引:1
林而达 《生态与农村环境学报》1993,(Z1)
文章总结了温室气体甲烷的最新研究进展,包括:甲烷对全球变暖的贡献,甲烷的排放机理以及优先研究的领域;估算了我国农业甲烷排放的贡献:中国约占世界人工源甲烷排放量的10.48%,其中农业排放占一半以上;根据实验结果,提出了筛选低排放水稻品种、水分管理、施肥管理、改进饲料、使用添加剂和生长调节剂、改进遗传、促进繁育等减少稻田和反刍家畜甲烷排放的若干技术选择。 相似文献
550.