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1.
It is argued that the research agenda on fertility decline needs to be explanatory rather than operational and not tied to government policy justification. The research agenda should be set in the broader developmental and geographic contexts and with consideration of cultural practices. Demographic and Health Surveys provide limited biosocial data, which does not provide a fuller analysis of the factors affecting contraceptive use and effectiveness. Clear associations are drawn between rising contraceptive use and fertility decline and are used as supports for national and international policy makers. Although policy formation may be justified by this research agenda, the view is taken that this is "bad science." Kenya has been used as a model for population change in Africa. Kenya is viewed as a country with obvious direct government involvement in policies on fertility reduction, which mirror the ideological biases of the global model. The global model assumes a universal relationship between fertility and contraceptive prevalence and attaches little significance to cultural differences. However, research recognizes that in Africa family relationships, land tenure, and economic organization are different and highly variable. If economic and social variables on Kenya were available, it is possible that the economic change hypothesis could be proven. Kenya has great regional differences and wide gaps in levels of development. For many countries population growth is the key factor in development, and policies reflect the threat of loan conditions or reductions in foreign aid. Many African countries moved in the direction of reducing population growth through improved health and education, more jobs, improved status of women, and other indirect measures. This approach relies on the Western model of demographic transition. This author argues that knowledge and conclusions about fertility in Africa are more conditioned by ideology rather than technical concerns. In the case of Kenya ideology is supported by research, but a fuller explanation of family formation is not yet available. Kenya's population policy is based on the contraception hypothesis, and data are not yet available for testing other alternative child mortality or economic change hypotheses and constructively informing policy makers about fertility decline.  相似文献   

2.
Using a sample of 885 females (1/2 of all married women of reproductive age), this study examines the role of education as a determinant of fertility among couples in Kullu town of Himachol Pradesh, India. Of the 885 respondents, only 149 were illiterate. The average family size was 2.88. Findings reveal that 1) the average family size was largest for illiterate respondents (3.57) and for illiterate males (3.76); 2) average family size declined consistently after the middle level of education to 1.29 for post graduate respondents and 2.33 for post graduate males; 3) a negative correlation exists between fertility and education of both husband and wife, with the wife's education having a stronger negative correlation with fertility; and 4) couples with an educational level of matriculation and above have a distinctly smaller family size than those less educated.  相似文献   

3.
Singapore experienced an extraordinary demographic transition from a population growth of over 4% per year in the late 1950s to around 1.6% in the 1990s and below replacement fertility since 1986. In 1987 official government policy shifted to measures for increasing fertility. This paper explores whether Singapore's pronatalist policies can reverse the demographic transition. The present policies aim to selectively increase fertility among the well educated. By 1987 the slogan switched from "stop at two" to "have three, if you can afford it." The policy included tax relief for a third child and other measures to encourage a third child. The policies are expected to have a different influence on society according to one's education, income, and family size. The government target is to selectively increase population by 40% over 25 years. Singapore's transition may follow the theory that low fertility is attained in societies where kin relationships are less important than personal educational achievements. The three ethnic groups responded differently to educational and fertility policies. The Chinese acquired the best education and attained the lowest fertility. The Chinese, who comprised 76% of total population in 1986, continued to have low fertility, while increases occurred among the Malays and the Indians. Future trends are considered difficult to predict. A survey conducted in 1992 in Ang Mo Kio among 489 reproductive age respondents revealed that Malays had the earliest marriage and first births before the age of 25 years (75% of Malays and 50% of Indians). The Chinese had their first child at 25 years or older. Without controls for the age of the mother, a strong statistically significant association was found between ethnic group and age at marriage and age at first birth. The relationship was not supported for current fertility. A comparison of women married for 5 years or less and 5 years or more revealed that women in recent marriages showed a greater likelihood of postponing marriage and childbirth for all ethnic groups. Since 1987, third order births as a percentage of all births increased from 21.47% before 1987 to 23.11% during 1987-92, which only suggests the favorable impact of the pronatalist policy. Educational changes are likely to become more influential in affecting choice of family size.  相似文献   

4.
This study elaborates on Indonesian fertility differentials based on the average number of children ever born or late births per woman. Other studies have shown that the relationship between fertility and economic class does not show a consistent pattern, being sometimes negative and sometimes positive. In the areas of Mojolama and Kedung Miri, characteristics such as occupation and economic status differ, but the relationship between age and economic status of the family was positive in both. In general, socioeconomic conditions in Majolama were better than in Kedung Miri but fertility levels were about the same at 3.6 children ever born/ever married woman in Mojolama and 3.5 in Kejung Miri, while the average of completed family size was the same, 4.8. There was a finding that women in higher economic classes tend to have a higher average number of children compared to those in lower economic classes.  相似文献   

5.
This article identifies some issues of importance in understanding China's policy of population control. This article presents evidence of trends in fertility, population policy, family planning, and socioeconomic change; and then discusses the conflict between fertility preferences and policy that is evident from studies of ideal family size and sex ratios. Some issues that are identified as "uncertain" include the extent of spread of family planning service delivery and its associated insurance schemes, local family planning policies and cadre responsibility systems, the demand for children, the demand for female children, the economic and environmental consequences of population growth, the fairness of reproductive restrictions and their application, and the extent of coercion in the later-longer-fewer policy era. It is argued that an ethical framework for analyzing China's population policy should include answers to questions about the harm to welfare from population growth, the government's right to demand voluntary reproductive sacrifice or to impose demographic or reproductive restrictions and punishment, and the government's right to impose coercion. If it is accepted that population growth in China has adverse consequences and its control would be beneficial to all, then it must be determined what the nature of the relationship should be between the state and the individual. The author refers to Walzer's (1983) position that the legitimacy of Chinese state power depends in part on whether political leaders at all levels are competent and not corrupt. The rights and duties of the government and individuals must be understood not just in terms of political legitimacy but also in terms of social justice. Social justice is dependent upon the degree of horizontal and vertical consultation and accountability, utilitarian consequences, and protected spheres of individual judgement. Utilitarian theories justify the one-child policy, while deontological theories support reproductive freedom as an absolute right.  相似文献   

6.
耦合自然-人文因素的沙漠化动态系统动力学模型   总被引：2，自引：0，他引：2  
沙漠化土地是自然、人文因素共同作用下的地表复杂系统,建立耦合自然-人文因素的沙漠化动态模型对于理解沙漠化演变过程、预测发展趋势以及进行科学调控具有重要的意义。本文以鄂尔多斯为典型研究区,利用系统动力学的方法,针对气候变化、土壤水分、人口、经济、放牧、土地利用六大沙漠化驱动力建立其与植被NPP的影响与反馈,结合不同沙漠化等级对应的NPP阈值范围,构建耦合自然-人文因素的沙漠化动态系统动力学模型。模拟的植被NPP与基于MODIS影像反演的实际NPP的对比表明,模型总体较为可靠。对不同情景下研究区2011-2030年植被NPP及沙漠化动态模拟分析表明,降雨是控制研究区沙漠化动态的主要因素,但在未来人类活动不变的情况下降雨量增加50%仍不能改变现有的沙漠化状态; 禁牧休牧相对于退耕还林还草、植树种草等政策更有利于植被恢复,但总体成本较高; 单独政策均无法改变现有的沙漠化状态,而这些政策的取消则会在不同的时间内导致沙漠化朝重度和极重度方向发展。对于地方政府而言,则需要根据自身经济状况合理选择不同政策组合来确保沙漠化的持续改善。  相似文献   

7.
１　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍｏｓｔｆａｒ－ｒｅａｃｈｉｎｇｅｃｏｎｏｍｉｃｒｅｆｏｒｍｔｏｄａｔｅｉｎＣｈｉｎａｗａｓｕｎｄｅｒｔａｋｅｎｉｎｔｈｅｔｗｅｎ－ｔｙｙｅａｒｓ１９７８～１９９８,ａｎｄｔｈｉｓｐｒｏｃｅｓｓｉｓｓｔｉｌｌｃｏｎｔｉｎｕｉｎｇ．Ｉｔｉｎｉｔｉａｌｌｙｓｔａｒｔｅｄｉｎｔｈｅａｇｒｉｃｕｌ－ｔｕｒａｌｓｅｃｔｏｒａｔｔｈｅｅｎｄｏｆｔｈｅ１９７０ｓ,ａｎｄｔｈｅｒａｄｉｃａｌｃｈａｎｇｅｓｉｎａｇｒｉｃｕｌｔｕｒａｌｐｏｌｉｃｉｅｓｈａｖｅａｆ－ｆｅｃｔｅｄａｌ…  相似文献   

8.
The Three-River Headwater Region (TRHR), known as the “Water Tower of China”, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity (NPP) is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we (1) summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research; (2) discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and (3) assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.  相似文献   

9.
Population policy and the 5-year plans since 1951 in India are reivewed and evaluated in terms of limiting population growth. The family planning (FP) programs have not had a major impact on people's attitudes, practice of contraceptives, or the average fertility rate. Not enough attention has been paid to the interaction of demographic structure and economic and social development, and the implications for limiting population growth. Vital elements of a population policy are containing population growth, limiting births among the young and reproductive age groups, enhancing employment options for males and females, diversifying the economy, improving literacy and educational standards, improving urban/rural ratios, and balancing male/female ratios. Several approaches to FP programs are possible: long term measures to improve the social, economic, and demographic structure, and short term measures to immediately avert births. Long term approaches recognize the complexity of the problem. Rapid socioeconomic development is the best contraceptive for controlling India's population. A well conceived population education program can help, as will increasing the marriage age, preventing children from entering the labor market, increasing female education levels, providing old age pension and social security and other insurance, and providing maternity benefits for small families. Short term measures may provide temporary or permanent methods of averting births; i.e., contraceptives, sterilization, penalties and rewards for small families. However, it must not be a bureaucratic measure imposed from above. It must be a self generating process. The author suggests that simultaneous long and short term approaches are necessary. Research should be conducted to delineate which measures have the most impact on reducing fertility and policy be formulated in accordance with these answers. Compulsion is required, and government should not hesitate to step in. In rural areas, traditional and modern methods in FP should be tried in order to achieve responsible behavior. The population increases in India were a result of a mortality decline starting in 1921 and a fertility decline starting in 1971. Attention must focus on high fertility areas such as Uttar Pradesh, Bihar, Madhya Pradesh, and Rajasthan. The 7th 5-year plan was important for making FP voluntary and generating an environment for fertility decline, and the 8th should establish FP as a self generating process.  相似文献   

10.
中国陆地净初级生产力时空特征模拟   总被引：83，自引：2，他引：81  
应用生态系统机理性模型估算1981～1998年中国陆地生态系统净初级生产力 (NPP) 的时空变化,并分析了NPP对年际间气候变化的响应。结果表明,中国陆地生态系统1981～1998年NPP总量波动于2.86～3.37 Gt C/yr之间,平均约为3.09 Gt C /yr ,单位NPP平均约为342 g C m2/yr。在研究时段内,NPP有缓慢增长趋势,年增长率约为0.32%,NPP总量平均值从 1980年代 (1981～1989年) 的3.03 Gt C/yr上升到1990年代 (1990～1998年) 的3.14 Gt C/yr。在一些厄尔尼诺 (El Nino) 发生年,NPP有明显的下降,但由于地域差异和季风环流的影响,NPP同ENSO的关系还十分复杂。从全国来看,在厄尔尼诺现象发生的1982年、1986年、1991年和1997年,NPP都有一定程度的减少。但在1993年和1994年两个厄尔尼诺发生年,NPP并没有表现为明显的下降趋势,1994年NPP总量甚至比上一年增加了0.12Gt,这主要是由于温度和降水量在不同地区的分布差异以及不同地区对厄尔尼诺现象的响应差异造成的。  相似文献   

11.
基于Biome-BGC模型的青藏高原五道梁地区NPP变化及情景模拟   总被引：2，自引：0，他引：2  
以“气候变暖”为标志的全球气候变化对青藏高原生态系统产生强烈影响,利用参数本地化的生物地球化学模型（Biome-BGC）对五道梁地区草地生态系统进行模拟,研究了该区域1961~2015年净初级生产力（net primary productivity,NPP）的变化,并进行了情景模拟。结果表明:五道梁地区近55 a草地年均NPP为67.94 g/(m 2·a),呈显著上升趋势,主要是由生长季延长以及9月份生物量快速增长造成。在该地区,温度是草地NPP的主导因子,降水变化在40%以内对生产力影响不显著;温度和降水交互影响NPP,对单一影响有放大作用,暖湿条件下NPP对气候变化响应更加明显。  相似文献   

12.
De Lange N 《Erdkunde》1993,47(1):61-74
The reduction of the rate of growth of the Brazilian population from 3% in the 1960s to 2% by 1993 resulted from a significant reduction of fertility. According to the 1986 national maternal-child health and family planning survey (PNSMIPF) results, 43.3% of women were using some type of contraception: 65.6% of married or cohabiting women. Women relied most on sterilization (17.2%), followed by oral contraceptives (OCs) (17%), the rhythm method (2.8%), the condom (1.1%), and others (5.2%). Only in the south was OC use more prevalent (28.5%) than sterilization (12.2%). The proportion of sterilization reached 27.8% in the north/center-east urban regions. In urban areas sterilization averaged 18.7% vs. 12.7% in rural areas. 26.9% of currently married women in the age range of 15-44 years had been sterilized. A 1990 international estimation indicated that the proportion of sterilization amounted to 36.9% in China, 30.95 in India, 29.7% in Brazil, 47.6% in South Korea, 30.4% in Thailand, and 36.5% in the Dominican Republic. The 1986 PNSMIPF survey also indicated that sterilized women were better informed than other women about contraception. 75% of the former had used OCs, 5% had used the diaphragm, 3% the IUD, 30% the condom, and 35% coitus interruptus at one time or other. The sterilized women had an average of 1.7 more children than those who were using other methods of contraception. 48.6% of women were sterilized before the age of 30, when they had had an average of 3.6 children. 66.6% of the sterilized women who had given birth before the age of 20 had 4 or more live births as compared to 5.9% of sterilized women aged 30 with the same number of children. 47% of women without any schooling were using some kind of contraception vs. 77% of those who had completed secondary school. A multivariate analysis also showed that the age of the mother, the number of live births, the educational status of the mother, and family income were positively correlated with sterilization.  相似文献   

13.
人口生育政策变化会对区域未来人口发展产生直接影响,“全面二孩”政策是继“单独二孩”政策之后逐步放宽生育政策的又一重大举措。结合政策变动,筛选政策受众人群进行精准化预测:未来15年,曲靖市20~39岁育龄妇女将净减少3.7万人,其中符合“全面二孩”生育政策且在20~39岁育龄妇女人口规模将缩减近0.7万;结合“全面二孩”政策最终兑现人口的测算,从2016年至2020年间会产生一个“二孩”生育高峰期,过了高峰期之后将渐落并减少至2.23万,较高峰期缩减0.82万人。“全面二孩”政策进一步调整和完善了生育政策,但后期效果不明显,面对“后人口转变”时代的到来,低生育率、老龄化的人口发展新格局,要实现人口与社会经济的协调发展,仍需与时俱进做出入口政策相应调整。  相似文献   

14.
Previous studies have found that urbanization often decreases net primary production (NPP), an important integrative measure of ecosystem functioning. In arid environments, however, urbanization may boost productivity by introducing highly productive plant communities and weakening the coupling of plant growth to naturally occurring cycles of water and nutrients. We tested these ideas by comparing NPP estimated for natural and anthropogenic land covers in the Phoenix metropolitan region of USA using MODIS NDVI data and a simplified parametric NPP model. Most anthropogenic land covers exhibited higher production than the natural desert. Consequently, the combined urban and agricultural areas contributed more to the regional primary production than the natural desert did in normal and dry years, whereas this pattern was reversed in wet years. Primary production of this urban landscape was only weakly correlated with rainfall, but strongly with socio-economic variables. Our productivity estimates agreed well with NPP predicted by a process-based ecosystem model for the area. Significant uncertainties, however, remain due to extremely high heterogeneity of urban vegetation. Nevertheless, our results clearly show that urbanization may not only increase regional NPP and disrupt the coupling between vegetation and precipitation, but also increase spatial heterogeneity of NPP in this arid region.  相似文献   

15.
Abstract

Creating resiliency, accomplished in part by individuals preparing for disaster, is the primary strategy outside of law enforcement for responding to the threat of urban terrorism. Individuals prepare when they perceive a need to do so, yet little is known about what shapes a person's awareness of vulnerability to terrorism. Because evidence indicates that social contacts act as conduits of information and affect perception of risk to natural hazards, it is possible that such contacts also affect terrorism vulnerability awareness. Because social contacts are also known to be systematically segmented by gender and location, we hypothesized that conversations about terrorism vary by gender and place, specifically the home and work place. Drawing on data from 93 interviews with householders in Boston, the study demonstrates that: (1) family networks generated discussions of home preparedness, whereas workplace networks engaged a wider variety of topics; (2) women discussed terrorism more frequently and in greater depth than did men; and (3) women heard more preparedness messages for the home than did men, whereas men undertook preparedness activities external to the home. The findings bridge geography and terrorism studies by theorizing emplaced and subjective human experiences that prompt conversations about terrorism. These conversations, in turn, help urban emergency managers and risk-hazards geographers promote rational dialogue and action vis-à-vis terrorism. Hazards researchers have shown that the more people discuss terrorism, the less they seek extreme and unwarranted responses.  相似文献   

16.
The paper examines the acceptance of birth control practices in India, and examines the relationhsip of these patterns to levels of economic development. A study of selected couples with markedly low incomes revealed that fertility tended to increase until a certain level of per capita income was reached. From this level onward, fertility and desired family size goals declined with increasing economic status. The study reveals an association in India between those less developed states and poor acceptance of family planning. The level of medical and administrative personnel for family planning services is superior in the more developed states and, logically, adoption of family planning practices is also higher. In higher-income states, characterized by relatively higher spatial mobility and literacy rates, the spread of family planning practices is relatively rapid. In less developed states, characterized by poorly developed centralized systems of communication and distribution, a lower spatial mobility of people, and a lower diffusion of knowledge through personal contact, family planning methods tend to spread very slowly or become less and less popular. A classification of Indian states as related to their acceptance of formal family planning policy and governmental efforts has been helpful in developing regionally-oriented program strategies for the future. Such strategies would take into account varying socioeconomic, cultural and administrative infrastructure differences in order to better assure delivery of services. As India also faces a shortage of trained physicians and personnel for the National Family Planning program, a regionally-based spatial allocation policy must be formulated that will divert some family planning personnel from states with high-acceptance patterns to the more densely populated, less developed regions of the country.  相似文献   

17.
气候变化对净生态系统生产力的影响   总被引：26，自引：0，他引：26  
周涛  史培军  孙睿  王绍强 《地理学报》2004,59(3):357-365
基于生态系统碳平衡方程以及净第一性生产力 (NPP) 和气候资料反演了1km分辨率的中国土壤异养呼吸系数 (aij),结果表明：aij总体上是东南和东北地区高,西北地区低;和NPP相比,东南沿海和华南的大部分地区的aij值并不大,而在东北北部和东部有大面积的aij高值区。这表明当气候适宜时,这些地区的土壤异养呼吸将具有较大的增长潜力。在假定气温平均升高1.5oC,降水平均增加5%的情景下,对中国净生态系统生产力 (NEP) 的研究表明：生态系统与大气的碳通量都有所增加,其中NPP平均增加了6.2%,土壤异养呼吸平均增加了5.5％,不同生态系统的NEP存在很大的差异,其中最稳定最有潜力的自然生态系统的碳汇是北方落叶针叶林;对人工植被而言,最多最稳定的碳汇是一年一熟作物;而双季稻连作喜温作物和单 (双) 季稻连作喜凉作物生态系统起着较稳定的碳源作用。  相似文献   

18.
The Three-River Headwater Region(TRHR), known as the "Water Tower of China", is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity(NPP) is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we(1) summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;(2) discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and(3) assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.  相似文献   

19.
Land use/cover change(LUCC)is a major factor affecting net primary production(NPP).According to the LUCC of the Loess Plateau from 2005 to 2015,the LUCC patterns in 2025 in three scenarios were predicted by using the Future Land Use Simulation(FLUS)model.Furthermore,taking the average NPP of various land use/cover types in 16 years as the reference scale,the changes in NPP in multi-scenario simulations are predicted and an-alyzed,and the impact of different land use/cover transfers on NPP is quantified.The results are as follows:(1)The land use/cover changes greatly in the baseline and fast development scenarios,and changes relatively little in the ecological protection scenarios.(2)The changes in NPP in different scenarios reflected the significant difference in the ecological protection effect.All the three scenarios promote an NPP increase,but the ecological protection sce-nario can promote NPP increases the most.(3)The changes in NPP caused by LUCC in the three scenarios reflected the significant difference in the various land use/cover types pro-tection effect.Analyzing and predicting NPP changes in multi-scenario LUCC simulations in the future can provide a theoretical basis for decision makers to judge the future changes in ecological environments and ecological protection effects against different policy back-grounds.  相似文献   

20.
提出以无人机季节航拍影像为数据源,采用ENVI5.3软件中的CART方法对广西北部湾的典型岛群红树林景观类型进行解译,借助于Python语言实现CASA模型并将其引入到对岛群红树林生态系统的研究中,得出了不同海岛和红树林生态系统净初级生产力（NPP）的空间分布特征。结果表明：1）可见光波段差异性植被指数（VDVI）可以很好地区分海岛及红树林植被等典型地物,可应用在岛群红树林生态系统NPP的估算上;2）研究区NPP的总量为127.09 t·C/a,NPP的年均碳密度值介于0~1 437.12 g·C/m2,年均碳密度为399.85 g·C/m2。红树林生态系统的NPP值较高,而海岛生态系统的NPP值较低;3）季节尺度上NPP碳密度的大小与年内太阳辐射有直接的关系,夏季的NPP碳密度最大,冬季最小;4）白骨壤的单位面积NPP最大,为1 123.09 g·C/m2,而桐花树最小,为649.65 g·C/m2。红树林生态系统NPP平均碳密度低于实测样地和深圳福田红树林计算结果,这与不同红树林群落的植被光谱特征有关。  相似文献   

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