城市用地与人口的异速增长和相关经验研究

由于城市土地利用变化涉及的因素多，使获取动态研究研究所需的资料十分困难，所以，用少数几个主要因素定量地表达其变化就显得十分重要。从前人的成果，即以人口表示的城市位序-规模法则和建成区面积表示的位序-规模法则出发，绽绎出城市的用地规模和人口数量呈异速增长。这意味着，如果把整个城市看成是一个生命有机体，那么作为反映城市特征的城市用地规模和城市人口这两个重要变量，就是城市这个有机体的两个器官，他们的增长率是成比例的。还通过这个关系建立了城市建成区面积与市场人口和经济发展水平的数学模式。对我国部分城市的经验研究在一定程度上分别证明了这两经验关系。     

盐碱化湿地稻-鱼复合生态系统微生物特征

为揭示盐碱化湿地稻-鱼复合生态系统微生物群落结构特征,1994-1995年,对松嫩平原苏打盐碱化湿地稻-鱼复合生态系统水体与土壤中的微生物数量及种群组成进行了初步研究。结果表明,稻-鱼湿地水体中异养细菌数量显著高于稻田湿地(P<0.05),季节变化特点为秋季>夏季>春季。异养细菌的数量分布与鱼产量有显著相关关系(r=0.879)。稻-鱼湿地系统的土壤微生物数量明显高于稻田湿地(P<0.01)。稻-鱼湿地和稻田湿地分别检测出10个和11个属的异养细菌。稻-鱼湿地系统1个生长期细菌的平均生物量为0.973g/m3,生产量为307.5 kg/hm2,所提供的鱼产力为7.0 kg/hm2。     

Population and environment in Australia: issues in the next half century

This paper considers the likely future population in Australia to 2050 and is cast within the context of environmental limitations, to which Griffith Taylor alerted the nation in the 1920s and 1930s, and for which he was vilified in several quarters. While acknowledging the relative accuracy of his long-range forecasts, the arguments here depart from environmental determinism, although varying sets of environmental ethics and values are considered in relation to Australia's global responsibilities and international commitments. It is argued that an increase in population to 26 million by 2050 will not place severe stresses on the physical environment, provided environmental and resource management strategies are put firmly in place, and if consumption and resource use practices are significantly modified. An ideological linkage exists between a resurgent Australian nationalism and a number of environmental perspectives, but one which rejects growth and biological diversity among humans while embracing environmentalism. This inward-looking nationalism–environmentalism is seen as harmful both to Australia's moral integrity as a nation, and in local and world citizenship.     

Modelling the effects of temperature and food on individual growth and reproduction of Daphnia and their consequences on the population level

Individual based simulations of population dynamics require the availability of growth models with adequate complexity. For this purpose a simple-to-use model (non-linear multiple regression approach) is presented describing somatic growth and reproduction of Daphnia as a function of time, temperature and food quantity. The model showed a good agreement with published observations of somatic growth (r² = 0.954, n = 88) and egg production (r² = 0.898, n = 35). Temperature is the main determinant of initial somatic growth and food concentration is the main determinant of maximal body length and clutch size. An individual based simulation was used to demonstrate the simultaneous effects of food and temperature on the population level. Evidently, both temperature and food supply affected the population growth rate but at food concentrations above approximately 0.4 mg Cl⁻¹ Scenedesmus acutus temperature appeared as the main determinant of population growth.

Four simulation examples are given to show the wide applicability of the model: (1) analysis of the correlation between population birth rate and somatic growth rate, (2) contribution of egg development time and delayed somatic growth to temperature-effects on population growth, (3) comparison of population birth rate in simulations with constant vs. decreasing size at maturity with declining food concentrations and (4) costs of diel vertical migration. Due to its plausible behaviour over a broad range of temperature (2–20 °C) and food conditions (0.1–4 mg Cl⁻¹) the model can be used as a module for more detailed simulations of Daphnia population dynamics under realistic environmental conditions.     

Are assemblages of black bream (Acanthopagrus butcheri) in different estuaries genetically distinct?

Samples of the estuarine-spawning teleostAcanthopagrus butcheri were collected from nine estuaries and a coastal lake, located in the Pilbara and South-western drainage divisions of Western Australia and distributed along a coastline covering a distance of nearly 2,000 km. The patterns of allozyme variation in these samples were used to explore the extent to which there was variation in the genetic compositions of black bream assemblages in geographically-isolated estuarine systems, and whether or not any such variation could be related to the geographical location or type of estuary. Although only three of 36 scorable loci (Gpi-1, Ldh andMdh-2) exhibited variation that could be used for analysis, there was considerable variation in allele frequencies at these loci among the different samples (mean F_ST=0.166). Much of the detected variation was attributable to differences between the samples collected from the two drainage divisions, which are located in very different climatic regions. Furthermore, the genetic compositions of samples from neighbouring estuaries were typically more similar to each other than to those of samples collected from more distantly-located systems. However, the assemblages in one west coast and two south coast estuaries, that are closed to the ocean for extensive periods of time during the year, all showed very similar genetic compositions. Nevertheless, it is crucial to recognise that, pairwise comparisons of samples collected from the different estuaries, both within and between the two drainage divisions, almost invariably showed statistically significant differences in allele frequencies at one or more loci. Thus, our results indicate that the local populations of black bream in individual estuaries are genetically distinct, which is probably a consequence of both a limited movement by individuals between estuaries and the effects of differences in regional and local environmental conditions.     

三峡工程永久船闸边坡岩体卸荷特性

从地貌学角度,分析了三峡工程永久船闸边坡岩体的自然及人为卸荷特性,指出了地表侵蚀、河流下切、开挖船闸等自然及人为地貌过程诱发了岩体的基本卸荷过程,构筑了一个三峡工程永久船闸边坡岩体卸荷特性的宏观模式。实地调砥及数值计算成果均表明,地貌分析法在分析实际岩体工程中,岩体卸荷特性方面具有较强的应用价值。     

三峡大坝建成后长江输沙量的减少及其对长江三角洲的影响

三峡大坝建成之后,大量泥沙滞留于库区,出库泥沙量减少,坝下河床冲刷而提供相当数量的泥沙,支流湖泊供沙也发生变化,这将使进入河口地区的泥沙有所减少。三峡大坝以上长江干流和支流建设新的大坝,南水北调、封山育林、退耕还林以及减少水土流失都将进一步减少长江进入河口地区的泥沙。由此估计,三峡大坝建成后的百年内长江输入河口地区的泥沙约为2.0×10⁸～2.5×10⁸t/a;冰后期长江三角洲形成和发育期间的长江年均输沙量为1.84×10⁸～2.28×10⁸t。二者的数值相当接近,然而与近50年的观测(4.33×10⁸t/a)相差甚远,长江流域的气候变化和人类活动可能是造成这一现象的原因。文章着重说明中国和长江上游人口的增长、种植作物的改变可能是水土流失、长江泥沙量增长的主要原因。     

人口生态生产:人地作用机制下"三江并流"世界遗产保护的新视角

基于不同人口需要而进行的人类活动对“三江并流”区的地理环境产生了巨大影响,形成了独具特色的人地作用机制。这一作用机制一方面对“三江并流”世界遗产的保护构成了威胁,但另一方面,通过人口生态生产,实现人口数量、质量、结构和分布的生态化,改进人类活动,也可优化“三江并流”区的地理环境,保护“三江并流”世界遗产,实现该地区的可持续发展。     

基于出租车上下客点的城市人口流动分析

掌握城市人口流动动态有利于进行交通预测、应急快速响应,以及合理的城市规划。出租车作为城市主要的交通运输工具之一,可以反映城市中人口的流动。本文以出租车上下客点数据为例,对比在工作日以及休息日的人口流动差异,分析出租车数据的空间分布及其动态变化,揭示城市人口流动模式。