Structure and Differentiation of Spruce Populations in Eastern Europe and Western Siberia

The structures and differentiation patterns of the Norway spruce (Picea abies) and Siberian spruce (P. obovata) populations have been studied in a wide area, including the transition zone of their continuous geographic range. The areas occupied by transitional populations have been detected. Series of distinct populations of the Norway and Siberian spruces are located to the west and east of them, respectively.     

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.     

Study on Simulating Spatial Distribution and Varying Patterns of Urumqi＇s Population

In this paper, an approach to simulate the spatial distribution of urban population is proposed using urban land use and population statistical data through the geographical information systems （GIS）. Then, the spatial population distribution of Urumqi as a case is simulated by the approach mentioned above and its varying patterns are analyzed by the raster population surface. As a result, producing raster population surface is more accurate and natural than the traditional choropleth map of population density. Concerning the spatial population distribution of Urumqi, the population density declines from south to north and the population distribution mainly presents＇ ＂T-type＂, the population distribution presents multicentre agglomeration and the population distribution of the districts shows different features. The population density varies significantly with the increase in the distance from central business district （CBD）. Finally, it is found in this paper that the development history of districts, terrain and traffic road are main factors that have an influence Urumqi＇s population distribution. This paper tries to provide more accurate population data for the plan and management of urban land, traffic and public facilities in order to enrich the researches on urban population distribution.     

广州市城市人口郊区化过程及其模式分析

我国正进入城市化的快速发展阶段．城市功能的聚集效应和扩散效应．都市圈化和效区化趋势在一些城市都有表现．因此将二者结合起来．研究我国城市化规律有重要意义。利用1982、1990、2000年三次人口普查中得到的广州市中心区和近郊区各街道、镇的人口密度资料．对广州人口密度分布进行模型研究。结果发现：1982年以来广州市城市人口密度分布呈典型的克拉克分布．即城市中心人口密度最大．随着向外距离的增加,人口密度迅速降低。表现出城市发展早期阶段的特征;与此同时,中心区人口密度先升后降.近郊区人口密度持续上升．远效区人口密度缓慢上升．城市郊区化开始发展。     

基于网格划分的宜兴市区滨水区可达性评价

城市滨水区可达性不仅仅是空间距离的阻隔,还包括人们对滨水空间的需求及滨水区自身对公众的吸引力。依据潜能模型的概念,选取人口密度、滨水区综合质量和以土地利用表达的交通作为评价因子,借助Arc-GIS9.3软件,建立了基于网格划分的滨水区可达性计算模型。该模型通过对研究区域进行等距网格划分以及定量计算网格内的人口密度、最小阻力成本和滨水区综合质量来进行滨水区可达性的定量评价。运用该模型评价了宜兴市中心城区居民至各滨水区的可达性水平,发现各滨水区平均可达性水平存在明显差异,最高的是团氿,最低的是蠡河;对每个滨水区而言,可达性从空间上均呈现出以滨水区为中心由内向外递减的趋势。评价结果可为城市滨水区合理     

上海市人口分布变动的空间特征分析

空间自相关分析是一种空间统计的方法。可以揭示区域变量的空间结构形态。通过对2000-2003年期间上海市乡镇人口密度变化率的空间相关性分析，发现上海市近几年人口分布空间变动格局表现为以中心城区为中心的环状分布模式，中心城区和远郊区人口密度变化小。人口增长缓慢，而近郊区人口密度变化大，人口增长迅速。全市人口密度变化率存在着显著的空间集聚现象。四种类型的空间关联在空间分布上具有明显的规律性。研究结果表明，目前上海市人口郊区化趋势明显。高人口密度区域在不断向外扩张，人口分布与经济、交通等社会发展因素的关系日益密切。这些研究结果说明利用空间自相关统计方法能够扩展和加强对人口分布空间模式的研究．从而为经济总体布局和城市化建设提供辅助参考作用。     

人口与消费对碳排放影响的分析模型与实证

从消费压力人口视角探讨碳排放问题,有利于正确判断和把握气候变化压力的人文因素,以及人口与消费可持续发展的动力学机制.本文通过对STIRPAT模型的扩展,应用岭回归方法计量分析人口、消费及技术因素对碳排放的影响.对我国1980至2007年碳排放情况的统计实证结果表明,扩展的STIRPAT模型对中国国情有较高的解释力.居民消费水平、人口城市化率、人口规模三个因素对我国碳排放总量的变化影响明显;现阶段我国居民消费水平与人口结构变化对碳排放的影响力已高于人口规模变化的影响力,居民消费水平与消费模式等人文因素的变化有可能成为我国碳排放的新的增长点;技术进步因素在此模型中对我国该阶段碳排放的解释力有限,表明我国未来通过技术进步减缓碳排放的潜力巨大.     

我国人口资源与食物问题

人口增多,耕地减少,部分地区供水不足,是我国人口与资源矛盾的基本格局。由于人口的压力,对资源实行超强度的利用,使较大范围的地区生态环境恶化,严重威胁农业生产,并成为许多地区多灾、低产、贫困的根本原因,较低的食物人均占有水平,将继续成为中国国民经济发展和人民生活水平提高的严重限制因素。增加食物,必须挖掘资源的潜力,开源与节流相结合,以内涵挖潜为主。首先是要立足现有的耕地,致力于提高单产;同时,合理开发水域、山地、草地等资源,广辟食物来源,提高非耕地资源的生产力,提高林牧渔业的发展水平。耕地应以深度开发为主,走资源节约型(节地、节水、节时、节能)的集约化道路。     

基于DMSP/OLS数据的江苏省城镇人口空间分异研究

人口空间分异研究是区域协调发展的基础,便捷准确地获取城镇人口全局和局域的空间信息,对于合理制定区域人口、经济和社会发展政策具有重要意义。在DMSP/OLS(夜间灯光)数据和人口数据之间的定量关联基础上,模拟出格网尺度上江苏省2012年人口密度,采用人口集中指数、空间变差函数识别人口分布的空间格局并探讨区别于行政单元尺度的人口格局形成机理。区域层面,江苏省人口空间分异呈现苏北地区\"低密度点状\"分布,苏南、苏中为\"高密度面状\"分布并存格局。城镇层面,江苏省人口空间分布结构具有4种类型,H-H型地区人口各向差异性最强,网格单元内随机变异最小;H-L型人口各向差异性最小,网格单元内随机变异较大;L-L型人口轴向均质化特征明显,网格单元随机变异较小;L-H型空间各向差异性较小,网格单元的随机变异最大。结果表明,基于DMSP/OLS夜间灯光数据反演而得到的人口格网模型具有巨大潜力,结合变差函数进行拟合分析可定量地刻画城镇内部人口分布的空间异质性特征。     

Externalities, Floating Population and Spatial Agglomeration

With the further development of socialist market economy, the mobility of factor markets in China, especially the labor market, is strengthened. Externalities interacts with the agglomeration of productive factors. Under the framework of new economic geography, this article presents a theoretical model involving the endogenous population density affected by urban externalities. Results show that the population density is more concentrated around the center because the degree and extent of interaction between individuals intensifies when the distance from the center decreases. When there are several externalities resources, the aggregation of externalities changes the configuration of spatial factor allocation. These results fit well with the empirical facts about the decreasing density of floating population along the cities of Guangzhou, Dongguan and Shenzhen in Guangdong Province which is situated in the eastern coast of the Pearl River Delta. We fred that under the impacts of externalities released from Hong Kong into the coast, floating population was more concentrated around Shenzhen and Dongguan, which are more adjacent to Hong Kong compared with Guangzhou City.