首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
INTRODUCTIONIn recent thirty years, due to the decreasing fertility andincreasing life expectancy, China's population is aging ata very rapid pace and the elderly population size is keepingon growing. During the dramatic aging progress, the oldestold group in China is catching our eyes. More and moreold people of China are becoming the oldest old. Theextremely old population (aged 80 and above) is increasingat 5.1% annually, while the old population above 65 isincreasing at 2.9%, and the…  相似文献   

2.
Abstract

Based on the current literature, this paper is mainly intended to test whether environmental factors and socio-economic factors will have direct effect on the longevity at county level in China in order to determine the major determinants affecting local longevity level. Using the multi-regression model, we find the result that factors such as temperature, climate, longitude, type of soils, as well as type of agricultural food production play a major role in shaping the longevity at county level, and that socioeconomic factors like infant mortality and gross death rate also have some direct impact on longevity, but the degree of impact is not as strong as the above environmental factors.  相似文献   

3.
针对南方红壤丘陵区农业资源利用的现状,以湖南省桃江县为例,应用灰色关联度模型定量分析了农业各部门产值对农业总产值的影响程度。结果发现,近50年来桃江县农业各部门的关联序列为:种植业(0.887 5)>牧业(0.760 2)>渔业(0.675 6)>林业(0.543 3)。种植业和牧业产值的变化对桃江农业总产值的波动起着主导作用。基于历史统计数据,利用灰色预测模型预测了2001~2005年5年内桃江县农业各部门产值的变化趋势。预测结果表明,各部门发展对农业总产值的关联度分别为:种植业(0.611 3)>渔业(0.358 7)>林业(0.347 6)>牧业(0.334 7)。比较两组关联序列可以清楚发现农业产业各部门的发展潜力。结合桃江农业资源和各部门的发展趋势,提出了桃江县农业结构优化调整的方向。  相似文献   

4.
通过建立引入气候因素的种植业生产函数模型,利用1990-2009年山东省40个县市种植业生产及气象面板数据,运用产出增长分解法,实证分析气候因素和非气候因素对山东省种植业产出的影响并对产出增长的各要素贡献进行分解。结果表明:气候变暖对山东省种植业带来明显的负面影响。1990-2009年间气候因素对山东省40个县市的总体产出增长的影响为-11.03%,在其他条件不变的情况下,平均温度每升高1℃,总体种植业总产值减少2.2%,总体产值增长下降1.48%;温度升高对鲁西北地区、鲁南地区种植业产出的影响最为明显;同时,降水对种植业产出影响显著,降水因素使得山东省种植业产出增长减少16.86%;物质投入中化肥和农药对种植业产出增长贡献最大,但农业劳动力减少,特别是种植业劳动力的减少,开始显著地影响种植业产出,使得种植业产出增长减少5.90%;技术进步的影响作用在下降。  相似文献   

5.
湖泊作为陆地水圈重要组成部分,是揭示全球气候变化与区域响应的重要信息载体。利用遥感技术获取青海省1990~2015年湖泊时空变化特征,并结合近25 a青海省气温和降雨量的时空变化特征以探究湖泊对气候的响应。结果表明:近25 a,青海省湖泊面积从12 757 km2增加到15 167 km2,湖泊数量由241个增加到286个。不同区域湖泊时空变化存在差异,主要包括3个区域:东部地区(Ⅰ)、西北地区(Ⅱ)和西南地区(Ⅲ)。其中,降雨量的增加促进了Ⅰ区域湖泊面积和数量的增加,湖泊面积由7 173 km2增加到8 474 km2,湖泊数量增加19个。Ⅱ区域湖泊面积由1 369 km2增加到1 542 km2,湖泊数量增加7个。该区域主要地形为柴达木盆地,是我国干旱区之一,干燥少雨,湖泊面积较少且变化剧烈。其湖泊扩张主要是因为降雨量增加,而较强的蒸散发极易导致湖泊萎缩。Ⅲ区域湖泊面积由4 215 km2增加到5 152 km2,湖泊数量增加19个。湖泊扩张的主要原因为降雨量的增加和蒸发的减少。研究为青海省湖泊科学利用与水资源合理配置提供了基础数据。 关键词: 青海省;湖泊;时空变化;气候变化响应  相似文献   

6.
基于GIS的湖北省水稻生产潜力研究   总被引:1,自引:0,他引:1  
使用GIS技术,以分县(市,区)为基本单位研究湖北省近年水稻生产状况。综合气象资料、地形数据、水稻作物生长发育规律和适应性气候指标,划分出湖北省水稻适宜性种植区域;根据各县(市、区)区域水稻实际生产数据,分早、中、晚稻划定出水稻生产的高、中和低产区域;测算湖北省水稻光温生产潜力为 17 000~22 000 kg/hm2,光温生产潜力可利用度为3306%~7830%。按照农业气候资源的相似性和农业气候利用一致性原则研究表明:湖北省水稻综合生产潜力为31742万t。该研究结果和建立的数据库为更好地指导和规〖JP2〗划湖北省水稻种植、生产和实施系列高产科技工程项目提供了依据和参考。该研究方法,能够扩展用于粮食作物种植区划和农业区划研究  相似文献   

7.
African mixed crop–livestock systems are vulnerable to climate change and need to adapt in order to improve productivity and sustain people’s livelihoods. These smallholder systems are characterized by high greenhouse gas emission rates, but could play a role in their mitigation. Although the impact of climate change is projected to be large, many uncertainties persist, in particular with respect to impacts on livestock and grazing components, whole-farm dynamics and heterogeneous farm populations. We summarize the current understanding on impacts and vulnerability and highlight key knowledge gaps for the separate system components and the mixed farming systems as a whole. Numerous adaptation and mitigation options exist for crop–livestock systems. We provide an overview by distinguishing risk management, diversification and sustainable intensification strategies, and by focusing on the contribution to the three pillars of climate-smart agriculture. Despite the potential solutions, smallholders face major constraints at various scales, including small farm sizes, the lack of response to the proposed measures and the multi-functionality of the livestock herd. Major institutional barriers include poor access to markets and relevant knowledge, land tenure insecurity and the common property status of most grazing resources. These limit the adoption potential and hence the potential impact on resilience and mitigation. In order to effectively inform decision-making, we therefore call for integrated, system-oriented impact assessments and a realistic consideration of the adoption constraints in smallholder systems. Building on agricultural system model development, integrated impact assessments and scenario analyses can inform the co-design and implementation of adaptation and mitigation strategies.F  相似文献   

8.
South Africa, a main food exporter in SADC, is characterised by a dual agricultural economy consisting of a well-developed commercial sector and smallholder, often subsistence, farming. Using the Ricardian cross-sectional framework, we examine the impact of climate change on a nationwide sample of crop, horticulture, livestock and mixed commercial farming systems. We find that a simultaneous decrease in precipitation and an increase in temperature will reduce productivity; and that an increase in temperature alone negatively affects farm output more than a decrease in precipitation. One of the most robust findings is the difference in the extent to which different commercial production systems will be impacted. That is, the results indicate that the strongest impact will be amongst specialised commercial crop farming system. In contrast, mixed farming systems appear to be the least vulnerable. This finding is consistent with studies on small-holder farms in sub-Saharan Africa. Hence, it appears that despite the likely benefits derived from economies of scale, commercial farms are, somewhat, equally vulnerable to climate change. Further, a province-wise assessment revealed that areas that already face disadvantageous climatic conditions will become even less productive. Overall, the findings suggest that practicing mixed farming methods will strengthen the resilience of commercial farms to climate change and that access to extensions—insurance and irrigation—is likely to reduce the risks.  相似文献   

9.
The impacts of climate change on crop yield have increasingly been of concern. In this study, we investigated the impacts of trends in sunshine duration (S) and maximum temperature (T max) on rice yields in Jiangsu Province at both the provincial and county level during the period from 1980 to 2008. The results showed that although S and T max both were positively correlated with rice yields, the combined impacts of the decreasing trend of S (0.37 h/decade) and the increasing trend of T max (0.34 °C/decade) in August caused a reduction of 0.16 t ha?1 in rice yields (approximately 1.8 %) in Jiangsu Province, and the trend of S had played a dominant role in the yield losses. Further analyses suggest that the increasing concentration of aerosols from rapid economic development in Jiangsu Province has caused a significant solar dimming at least since 1960, making mitigations and adaptation measurements on regional haze impact imperative. Our study provides a prototype for detecting negative feedback on agricultural production caused by intensified anthropogenic activities that aim only to create rapid economic development.  相似文献   

10.
随着开发区集约利用评价工作的全面开展,合理界定其用地规模成为研究的重点。本文以南京市为例,首先运用多目标决策法评价开发区集约利用等级,然后采用逐步回归法选取与集约利用相关度较大的因素作为预测依据,进而计量其合理的规模。研究结果表明:其一,A、B和C开发区集约等级为II级,可以适当扩大开发区规模;D、E、F和G开发区集约等级为III级,应该维持开发区规模;而H和I开发区集约等级为IV级,应适当缩小开发区规模。其二,当B开发区、A开发区和其他开发区地均工业总产值增长率分别达到23.10%、18.18%和15%时,可以充分发挥土地利用潜力。其三,即使实现土地集约利用,B开发区仍需扩充6.08 km2。最后,本文提出通过科学设定地均工业总产值增长率来提升开发区集约利用水平的政策建议。  相似文献   

11.
研究经济发展的周期性及其驱动因素,"淡化"经济周期的剧烈波动,对优化调控经济管理、促进经济稳定增长具有重要意义。采用经验模态分解(Empirical Mode Decomposition,EMD)和偏最小二乘回归(Partial Least squares Regression,PLSR)相结合方法,对1952~2007年湖北人均GDP进行了多尺度分析及不同时间尺度下的驱动因素分析。结果发现:(1)56 a来,湖北人均GDP在波动中不断增长,存在准47 a、准112 a和准56 a 3个波动周期和一个先轻微下降后持续递增的趋势项;(2)湖北人均GDP不同周期性波动的共同驱动因子有资本形成总额、原煤产量、水泥产量、进出口总额、旅客周转量,不同因子及其驱动大小分别为准47 a依次有社会消费品零售总额、居民消费、农林牧渔总产值、钢产量、货物周转量,准112 a依次有社会消费品零售总额、发电量、农林牧渔总产值、钢产量,准56 a依次有居民消费、政府消费、邮电业务总量,趋势项依次有社会消费品零售总额、居民消费、政府消费、发电量、农林牧渔总产值、钢产量、邮电业务总量、货物周转量。湖北及中央政府相关政策制定者应特别关注促进资本积累与形成,有效调控原煤与水泥等主要工业产品产量,制定合理的进出口贸易政策,提高旅客运输效率及运输能力等。
  相似文献   

12.
采用《省级主体功能区域划分技术规程》的技术流程和评价方法,基于GIS技术,以交通网络密度Di、交通干线影响度Ci和区位优势度Si为指标,对江苏省62个县域单项指标和集成性指标进行测算,分析了江苏省交通优势度的空间分布特征和成因。研究发现:(1)交通优势度区域差异明显,南高北低;(2)交通优势度具有空间自相关性,高值区和低值区呈现出相对集聚镶嵌分布的空间格局,形成以沿沪宁线和沿江地区分布的高值区,沿废黄河、沿洪泽湖和沿海分布的低值区;(3)交通优势度和经济发展水平具有较强的耦合性,两者相关系数达到0.798;(4)交通优势度呈现正偏态的特征。12.1%的面积具有突出的交通优势,2.7%的面积处于交通缺乏区域,大约68%的面积处于中等或较低区域。加强低值区的交通基础设施建设,加强各县域与上海和13个省辖市的经济联系,提高江苏交通优势度,为江苏区域发展提供支撑和保障作用。  相似文献   

13.
流域脆弱性评价中,如何有效结合自然及社会等多方面因素开展较大区域尺度评价是目前研究的难点之一,特别是结合灾变山地环境影响,开展小流域脆弱性评价,对于山区流域防灾减灾及可持续发展具有积极的指导意义。采用栅格单元与小流域单元相结合的评价方法,综合自然与社会因素,并引入活跃灾害事件对小流域脆弱性的影响,从灾害危险度与社会易损性角度构建评价体系,应用3S技术,选取彭州龙门山区开展典型案例研究,开展灾变山地环境影响下的小流域脆弱性评价。最终将研究区小流域脆弱性划分为轻度、中度、高度及重度4个等级,各级含小流域个数分别为12、21、27及17个,相应面积占整个研究区面积的比例分别为11.53%,38.63%,40.46%及9.38%。针对区域内重大灾害事件,对评价结果进行验证表明,综合自然和社会因素,并引入灾害事件构建评价体系,并以栅格与小流域单元相结合的评价方法,对灾变山地环境下较大区域尺度流域脆弱性评价具有可行性,可为区域尺度小流域脆弱性评价研究提供一定参考。  相似文献   

14.
气候变化对江苏省经济的影响研究   总被引:4,自引:1,他引:3  
利用经济学上的“投入-产出”分析方法,结合气候变化对农业产量影响的计算机模拟系统,研究了当气候变化影响农业生产和产量时,江苏省农业产值的变化及与农业部门相联系的国民经济各个部门产出量的变化。考虑江苏省的经济发展速度和产业结构,预测了未来不同的气候变化情景下,为使经济发展达到预期目标,社会需对各经济部门追加的资金投入量及各经济部门之间相互投入量的变化,提出了适应气候变化的相应对策。研究结果反映了国民经济各部门之间及部门与整体的相互联系,从而对制定区域经济平衡发展规划提供了理论依据和建议。  相似文献   

15.
利用经济学上的“投入—产出”分析方法 ,结合气候变化对农业产量影响的计算机模拟系统 ,研究了当气候变化影响农业生产和产量时 ,江苏省农业产值的变化及与农业部门相联系的国民经济各个部门产出量的变化。考虑江苏省的经济发展速度和产业结构 ,预测了未来不同气候变化情景下 ,为使经济发展达到预期目标 ,社会需对各经济部门追加的资金投入量及各经济部门之间相互投入量的变化 ,提出了适应气候变化的相应对策。研究结果反映了国民经济各部门之间及部门与整体的相互联系 ,从而对制定区域经济平衡发展规划提供了理论依据和建议。  相似文献   

16.
Vietnam is prone to tropical storms. Climate change effects contribute to sea level rise, floods, progression of the low water line and coastal erosion. This paper inventories the perception of local people, assesses and values main aspects of the livelihood damage caused by the tropical storms of the period 2008–2013 in three coastal communes of the Ky Anh District of the Ha Tinh Province in Central Vietnam. The communes were selected because the location of their coastal line is perpendicular to the storm itself, which made them prone to damage. The effects of increasingly extreme weather conditions on three communities in an area most affected by storms and floods on the local residents and their responses to these changing environmental conditions are analyzed and assessed. The results of questionnaires completed by randomly selected local inhabitants of these communes show that storms and related hazards such as flood, sea level rise and heavy rain are perceived as the most impacting climate change intensified phenomena on agriculture and aquaculture, livestock, household property and income. Opinions and measured data provided by the commune and district authorities allow estimating the total direct cost of the tropical storm at 1.56 million $US (The used conversion rate VND/$US is 21,730 when the research was conducted in 2014) during the period 2008–2013. The long-term costs of adaptation and social impact measures will be significantly higher. Details of the monetary figures allow identifying the physical and natural capital of the area as being most affected by the storm. Trend and cost analysis show that the total financial support for hazard prevention and management during 2014–2019 is estimated at 1.19 up to 1.32 million $US. Local stakeholders indicate that climate change adaptation should not be limited to technical measures such as strengthening dikes, but also should target planting protection forests and mangroves and land use planning. Financial support for the relocation policy, stakeholder involvement and integrating climate change adaptation in both the socioeconomic development master plan and local land use planning are also of importance.  相似文献   

17.
岷江上游地区的草地资源与畜牧业发展   总被引:4,自引:0,他引:4  
岷江上游草地面积837226hm^2,大约占了该区土地面积的35%。这块草地蕴藏着丰富的生物多样性,具有重要的生态学功能,是岷江上游绿色生态屏障的重要组成部分。高山草甸草地和亚高山草甸草地是该区的主要植被类型,其面积分别占草地总面积的54.8%和17.2%,其产草量分别占该区各类草地总产草量的53.47%和26.46%。岷江上游各县天然草地的面积和各县草地畜牧业在经济结构中所占的比重都表现了从高海拔到低海拔递变的趋势,基本上与植被的垂直梯度变化相耦合。指出了当前草地畜牧业发展存在的一些问题:超载过牧现象严重,生产效率低下,集约化水平低。除了饲草的生产与加工、畜种改良和草种改良等措施外,结合岷江上游的实际情况,在发展的思路和技术措施上着重阐述了以下几个方面:发展特色畜牧业,摒弃头数畜牧业;以市场为导向的主动畜群时空周转;结合“天保工程”和“退耕还林工程”,促进农林牧业的紧密结合。  相似文献   

18.
The IPCC Working Groups I–III 2007 publications does not consider the question of the influence of the entropy increase in the atmosphere on current climate development. An investigation into this question, both in general terms as well as by two quantitative approaches, reveals we must consider the entropy produced by man in connection with climate development, especially with regard to the temperature increase of the atmosphere. The IPCC report also fails to mention the production of CO2 by humans and livestock, but calculations show we must also consider such greenhouse gas CO2 production. For solving the mitigating processes, we therefore have to take into account both the human induced entropy production and the direct human and livestock CO2 output. In consideration of these findings, it seems necessary to introduce an “entropy identity” to people who wish to be able to continue to live on the planet. The introduction of an entropy tax might also help in solving the most urgent fundamental problem humanity has ever had to face. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   

19.
Forage and more widely grassland systems are difficult to analyze in economic terms because a large proportion of what is produced is not marketed. Economic misestimation of these farm products may dramatically alter projected climate change impacts. This study estimates the economic value of grass and assesses the impact of climatic variations on grassland–livestock systems by taking various environmental and climatic factors into account. Accordingly, grass yield responses to nitrogen inputs (N-yield functions) have been simulated using the grassland biogeochemical PaSim model and then fed into the economic farm-type supply AROPAj model. We developed a computational method to estimate shadow prices of grass production, allowing us to better estimate the effects of climatic variability on grassland and crop systems. This approach has been used on a European scale under two Intergovernmental Panel on Climate Change climate scenarios (AR4 A2 and B1). Results show a significant change in land use over time. Accordingly, due to decreases in feed expenses, farmers may increase livestock, thereby increasing overall greenhouse gas emissions for all scenarios considered. As part of autonomous adaptation by farming systems, N-yield functions extending to pastures and fodders allow us to improve the model and to refine results when marketed and non-marketed crops are considered in a balanced way.  相似文献   

20.
利用川西高原31个气象观测站1961~2012年的观测资料,采用线性趋势法、Mann-Kendall突变检测法和Morlet小波分析方法,详细分析了川西北高原畜牧业界限温度0℃初日、5℃终日及0℃初日至5℃终日之间畜牧气候资源的变化特征。结果表明:(1)川西北高原稳定通过0℃初日及5℃终日在区域上有很大差异,主要受海拔高度、纬度的影响。(2)畜牧气候资源的年际变化总体呈增加趋势,但区域变化不均;(3)各要素年代际变化不同,积温在各个年代都比前一年代增加,而日照时数则呈现出一增两减一增的趋势,降水量的年代际变化型式与日照相反,呈现一减两增一减的趋势;(4)各因素突变特征明显,突变的时间主要出现在20世纪80年代,不同因素的突变类型不同;(5)畜牧业气候资源存在明显的周期性变化,各要素变化周期长短不一致,尤其是降水量以4a左右的短周期振荡为主。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号