Will Limits of the Earth's Resources Control Human Numbers?

The current world population is 6 billion people. Even if we adopted a worldwide policy resulting in only 2.1 children born per couple, more than 60 years would pass before the world population stabilized at approximately 12 billion. The reason stabilization would take more than 60 years is the population momentum – the young age distribution – of the world population. Natural resources are already severely limited, and there is emerging evidence that natural forces already starting to control human population numbers through malnutrition and other severe diseases. At present, more than 3 billion people worldwide are malnourished; grain production per capita has been declining since 1983; irrigation per capita has declined 12% during the past decade; cropland per capita has declined 20% during the past decade; fish production per capita has declined 7% during the past decade; per capita fertilizer supplies essential for food production have declined 23% during the past decade; loss of food to pests has not decreased below 50% since 1990; and pollution of water, air, and land has increased, resulting in a rapid increase in the number of humans suffering from serious, pollution-related diseases. Clearly, human numbers cannot continue to increase.     

中国经济实现持续增长面临的城市化滞后的挑战

我国人口城镇化滞后的根本原因在于计划经济体制下形成的二元经济结构和城乡隔离的户籍管理制度没有在工业化进程和市场经济体制建立进程中予以破除。而城镇化的滞后将给我国经济实现持续增长带来诸多挑战，包括有效需求不足、农业生产率低下、产业结构难以升级等。文章特别阐明通过包括户籍制度、就业制度和土地承包制度在内的制度创新，加快人口城镇化的步伐，促进经济持续稳定的增长。     

关于中国土地资源人口承载力问题的思考

土地资源的人口承载力问题也就是生存空间问题,它关系到人类未来的生存与发展问题,历来受学术界的注目。20世纪70年代联合国粮农组织(FAO)曾主持了一项大型的发展中地区土地资源人口承载力问题的研究,80年代后期,中国科学院—国家计委自然资源综合考察委员会也主持了一项大型的中国土地资源生产能力及人口承载量研究。相应地还有一系列有关中国未来的生存与发展和人口承载力问题的探讨。本文从中国人地关系变化的角度介入这一讨论,分析中国远期的土地资源是否超载的问题。     

上海人口自然变动负增长与社会经济发展

1993年上海人口自然变动在全国率先进入负增长,自然增长率为-0.78‰,并将持续一个较长的时期。这是长期以来本市经济和社会发展以及计划生育工作共同作用的必然结果,其中计划生育政策的成功推行起着重要的作用。上海除了继续控制人口增长的数量外,还要调节人口规模和人口结构,大力提高人口素质,不断使人口与社会经济发展、生态平衡、资源利用等方面达到协调发展。由负增长引发的劳动力短缺和老龄化程度加剧要采取相应的对策。     

Acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase, lactate dehydrogenase and catalase of the mosquitofish, Gambusia holbrooki

The objective of this study was to investigate both acute and chronic effects of clofibrate and clofibric acid on the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and catalase (CAT) of the mosquitofish (Gambusia holbrooki). AChE, commonly used as a biomarker of neurotoxicity, was determined in the total head. LDH, an important enzyme of anaerobic metabolism, was quantified in dorsal muscle, and CAT, enzyme which has been used as indicative parameter of peroxisome proliferation, was determined in the liver. Furthermore, alterations of body and liver weight were also determined, through the calculation of the ratios final body weight/initial body weight, liver weight/final body weight, liver weight/gills weight and liver weight/head weight. Acute exposure of G. holbrooki to both clofibrate and clofibric acid induced a decrease in liver CAT activity, an increase in muscle LDH activity, while no effects were observed on AChE activity. However, chronic exposure did not alter significantly the enzymatic activities, suggesting reduced or null effects over these pathways, relative to effects reported in other species. No effects were observed for the calculated ratios, except a significant weight reduction for males chronically exposed to clofibrate.     

Assessing Landowner Activities Related to Birds Across Rural-to-Urban Landscapes

Fluctuations of bird abundances in the Midwest region of the United States have been attributed to such factors as landscape change, habitat fragmentation, depredation, and supplemental feeding. However, no attempt has been made to estimate the collective role of landowner activities that may influence birds across a landscape. To investigate how landowners might influence birds when the majority (> 90%) of land is privately owned, we surveyed all 1694 private domestic landowners living on three breeding bird survey routes (120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan from October through December 2000. Our survey was designed to investigate (1) the proportion of landowners involved in bird feeding, providing bird houses, planting or maintaining vegetation for birds, gardening, landscaping, applying fertilizer, and applying pesticides or herbicides; (2) whether differences existed between urban, suburban, and rural landowner activities; and (3) whether landowners that carried out a given activity were sociodemographically different from those who did not. Of the 968 respondents (58.5% response rate), 912 (94%) carried out at least one of the activities on their land and the average landowner carried out 3.7 activities. A total of 65.6% fed birds, 45.7% provided bird houses, 54.6% planted or maintained vegetation for birds, 72.7% gardened, 72.3% landscaped, 49.3% applied fertilizer, and 25.2% applied pesticides or herbicides. Significant differences existed between the landscapes, with rural landowners having more bird houses and applying pesticides or herbicides in greater frequency. Similarly, urban landowners had a greater density of bird feeders and houses, but planted or maintained vegetation in the lowest frequency. Participation in activities varied by demographic factors, such as age, gender, and occupation. Scaling each activity to all landowners, including nonrespondents, across all landscapes indicates that between 14% and 82% of landowners may be engaged in a particular activity, with application of pesticides or herbicides having the least potential involvement (13.9%–55.4%) and gardening having the greatest potential involvement (40.1%–81.6%). Taken collectively, our results indicate that landowners are both intentionally and unintentionally engaged in a wide range of activities that are likely to influence bird populations.     

Food and hunger in Sub-Saharan Africa

Sub-Saharan Africa is by far and away the most disadvantaged of the world's three main developing regions. Worse, its situation has mostly been deteriorating for much of the past several decades. Its agriculture is severely under-productive, and per capita food supplies have been steadily dwindling. Its environments and natural-resource base, characterised by water deficits, soil erosion, fuelwood shortages, rudimentary agro-practices, and grossly inadequate infrastructure, are generally unfavourable for sustainable agriculture. The population has expanded until it far exceeds carrying capacity, yet its growth rate is the highest in the world. The region also suffers from more disease than any other region. There is widespread and deepening poverty. As a result of these and other problems, and despite major food imports, two-thirds of the people are malnourished, one-quarter of whom endure outright hunger, even semi-starvation. Both these proportions appear set to keep on increasing both relatively and absolutely. Were these problems to persist with their decades-long trends, there could eventually arrive a stage when much larger numbers of people would succumb to terminal malnutrition, precipitating a human tragedy of unprecedented proportions. Fortunately, success stories demonstrate that solutions are available, on the part of both governments concerned and international agencies. Because of ignorance, or rather ignore-ance of the potential mortality disaster ahead, however, not nearly enough has been done to address the challenge with the energy and urgency to match its scale.     

江苏省人口产业结构与环境污染的关系研究

对江苏省1990年至2003年人口产业结构及环境污染的指标进行量化分析研究，建立了江苏省人口产业结构与环境污染之间的关系模型，并对影响污染物排放量的人口产业指标进行了分析。