Influence of China''s Population Mobility on the Change of Regional Disparity since 1978

In this study, an econometric model about population mobility and economic growth is used to show the unbalanced distribution of population mobility in different region was remarkably related to that of regional economic growth and the large number of movers had a significant influence on regional economic growth and developing disparity. On the basis of this study, we conclude that China's population mobility also had a significant influence on the structure and tendency of regional disparity, and the population mobility enlarged the regional disparity of the whole nation, the East, and the West since the reform, besides the Midst during 1978 to 1987. Furthermore, the population mobility accelerated the increase of regional disparity in the whole nation, the Midst, and the West, but at the same time, retarded that in the East in the period of 1996–2003.     

The Impact of Increased Environmental Stochasticity Due to Climate Change on the Dynamics of Asiatic Wild Ass

Abstract:  Theory proposes that increased environmental stochasticity negatively impacts population viability. Thus, in addition to the directional changes predicted for weather parameters under global climate change (GCC), the increase in variance of these parameters may also have a negative effect on biodiversity. As a case study, we assessed the impact of interannual variance in precipitation on the viability of an Asiatic wild ass ( Equus hemionus ) population reintroduced in Makhtesh Ramon Nature Reserve, Israel. We monitored the population from 1985 to 1999 to determine what environmental factors affect reproductive success. Annual precipitation during the year before conception, drought conditions during gestation, and population size determined reproductive success. We used the parameters derived from this model to assess population performance under various scenarios in a Leslie matrix type model with demographic and environmental stochasticity. Specifically, we used a change in the precipitation regime in our study area to formulate a GCC scenario and compared the simulated dynamics of the population with a no-change scenario. The coefficient of variation in population size under the global change scenario was 30% higher than under the no-change scenario. Minor die-offs (≥15%) following droughts increased extinction probability nearly 10-fold. Our results support the idea that an increase in environmental stochasticity due to GCC may, in itself, pose a significant threat to biodiversity.     

Population dynamics of the bank vole as studied using sequence functions

Sequence functions were used to construct a simulation model of the long-term population dynamics of the bank vole in Karelia. The mechanisms of population reproduction control affect the population size if it is greater than 1 and 4 ind./100 trap-days in spring and autumn, respectively.     

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.     

人类活动净氮输入时空变化特征及其影响因素——以香溪河流域为例

为了阐明人类活动对三峡库区第一大支流香溪河流域氮输入的影响程度,基于人类活动净氮输入（NANI）模型估算了2001~2015年间香溪河流域乡镇水平的人类活动净氮输入,分析了氮输入的主要来源及其动态变化.结果表明：时间尺度上,香溪河流域人类活动净氮输入（NANI）因氮素施用的变化而呈现先上升后下降最后上升的趋势,但2015年相对2001年的NANI下降了143kg N/（km²·a）;空间尺度上,香溪河流域NANI整体呈现北低南高的分布格局,其中NANI输入强度差异较大的区域主要有昭君镇、峡口镇和黄粮镇.从人类活动净氮输入的组成上来看,氮肥施用仍然是最主要的来源（40.06%）,其次为大气氮沉降（29.98%）和食品/饲料净氮输入（27.75%）,作物固氮仅占净氮输入总量的2.21%.香溪河流域的NANI与人口密度和耕地面积比例极显著相关（P<0.001）;而NANI与河流氮输出的相关性不显著,香溪河流域河流氮输出占NANI的比例仅为24.28%.因此,可以通过减少氮素施用降低流域尺度氮素净输入量,但该流域NANI与河流氮输出无直接的响应关系.     

人口与可持续发展

有限的资源不能支撑无限增加的人口，面对高速增长的人口，人们产生了种种不同的认识。本文分析了人口增长与食物供给，人口增长与生态环境和经济发展的矛盾；阐述了最大人口容量及经济最优人口计算需要考虑的因素和基本；提出我国必须坚持严格控制人口增长的政策，这是可持续发展的需要。     

Discussion of Population Modernization Theory and Actuality Analysis of Population Modernization in China

This paper discusses the basic concept and connotation of population modernization. The author briefly analyzes the actuality of population modernization in China, gives some advice and puts forward some measures.     

Estimating Sustainable Bycatch Rates for California Sea Lion Populations in the Gulf of California

Abstract:  Commercial and subsistence fisheries pressure is increasing in the Gulf of California, Mexico. One consequence often associated with high levels of fishing pressure is an increase in bycatch of marine mammals and birds. Fisheries bycatch has contributed to declines in several pinniped species and may be affecting the California sea lion ( Zalophus californianus ) population in the Gulf of California. We used data on fisheries and sea lion entanglement in gill nets to estimate current fishing pressure and fishing rates under which viable sea lion populations could be sustained at 11 breeding sites in the Gulf of California. We used 3 models to estimate sustainable bycatch rates: a simple population-growth model, a demographic model, and an estimate of the potential biological removal. All models were based on life history and census data collected for sea lions in the Gulf of California. We estimated the current level of fishing pressure and the acceptable level of fishing required to maintain viable sea lion populations as the number of fishing days (1 fisher/boat setting and retrieving 1 day's worth of nets) per year. Estimates of current fishing pressure ranged from 101 (0–405) fishing days around the Los Machos breeding site to 1887 (842–3140) around the Los Islotes rookery. To maintain viable sea lion populations at each site, the current level of fishing permissible could be augmented at some sites and should be reduced at other sites. For example, the area around San Esteban could support up to 1428 (935–2337) additional fishing days, whereas fishing around Lobos should be reduced by at least 165 days (107–268). Our results provide conservation practitioners with site-specific guidelines for maintaining sustainable sea lion populations and provide a method to estimate fishing pressure and sustainable bycatch rates that could be used for other marine mammals and birds .     

The Spatiotemporal Structure of Rodent Populations in the Steppe Zone of Western Siberia

The spatial structure of populations has been studied in two rodent species inhabiting the subzone of meadow steppes of the steppe zone of Omsk oblast: the narrow-sculled vole (Microtus gregalis Pall.) and steppe lemming (Lagurus lagurus Pall.). Their populations are represented by combinations of territorial family groups whose structure and spatial distribution vary by season depending on population density, the phase of the population cycle, and the status of their members in the population. In the areas cohabited by M. gregalis and L. lagurus, the pattern of territory use and the rhythm of animal activity during the day depend primarily on their total density: under conditions of low density, the population groups of both species are spatially separated; at increased density, they are distributed with respect to the pattern of daily activity. Both species jointly use part of the territory but at different times of day: M. gregalis, mainly at night and in the morning; L. lagurus, in the daytime.