Proximate Population Factors and Deforestation in Tropical Agricultural Frontiers

Forest conversion for agriculture expansion is the most salient signature of human occupation of the earth's land surface. Although population growth and deforestation are significantly associated at the global and regional scales, evidence for population links to deforestation at micro-scales—where people are actually clearing forests—is scant. Much of the planet's forest elimination is proceeding along tropical agricultural frontiers. This article examines the evolution of thought on population–environment theories relevant to deforestation in tropical agricultural frontiers. Four primary ways by which population dynamics interact with frontier forest conversion are examined: population density, fertility, and household demographic composition, and in-migration.     

Using stylized agent-based models for population–environment research: a case study from the Galápagos Islands

Agent-based models (ABMs) are powerful tools for population–environment research but are subject to trade-offs between model complexity and abstraction. This study strikes a compromise between abstract and highly specified ABMs by designing a spatially explicit, stylized ABM and using it to explore policy scenarios in a setting that is facing substantial conservation and development challenges. Specifically, we present an ABM that reflects key Land Use/Land Cover dynamics and livelihood decisions on Isabela Island in the Galápagos Archipelago of Ecuador. We implement the model using the NetLogo software platform, a free program that requires relatively little programming experience. The landscape is composed of a satellite-derived distribution of a problematic invasive species (common guava) and a stylized representation of the Galápagos National Park, the community of Puerto Villamil, the agricultural zone, and the marine area. The agent module is based on publicly available data and household interviews and represents the primary livelihoods of the population in the Galápagos Islands—tourism, fisheries, and agriculture. We use the model to enact hypothetical agricultural subsidy scenarios aimed at controlling invasive guava and assess the resulting population and land cover dynamics. Findings suggest that spatially explicit, stylized ABMs have considerable utility, particularly during preliminary stages of research, as platforms for (1) sharpening conceptualizations of population–environment systems, (2) testing alternative scenarios, and (3) uncovering critical data gaps.     

Urban influences on farmland use in New York State

This article assesses the relationship between demographic change and structural adjustments in agriculture. A number of demographic and economic analyses have posited an inverse relationship between post-1950 exurban population growth and agricultural viability, especially in the Northeast Region of the USA. To test this hypothesis, a multivariate model of percent change in county land in farms over the period 1950–1987 is estimated, and the findings only partially support the population hypothesis. Estimation results indicate that the effect of core metropolitan status is significant, but that the effects of rural population change, rural nonfarm population change, and county population deconcentration are not. The analysis demonstrates that maintenance of land in farm use largely depends upon economic forces that are national and regional in scope, and almost exclusively outside the purview of state and local farmland protection programs.     

Land Use and Marriage Timing in Nepal

I examine the relationship between patterns of land use and marriage timing in the Chitwan Valley, a rural area in south-central Nepal. In this setting, I conceptualize a relevant dimension of land use as the portion of land in each neighborhood devoted to agriculture. Using discrete-time event history models, I examine the relationship between the proportion of land devoted to agriculture and the rate of marriage among 811 never-married individuals aged 15–20 years. Agricultural land has a positive association with marriage rates. As potential intervening mechanisms between agricultural land and marriage rates, I propose nonfamily organizations, school and work activities, and local marriage markets. A portion of the relationship between land and marriage rates appears to be mediated through the accessibility of nonfamily employers. Respondents’ actual employment activities, however, fail to mediate the effects of agricultural land or nonfamily employers. The precise mechanisms linking land use to marriage remain unclear.     

Water Resources,Land Exploration and Population Dynamics in Arid Areas - The Case of the Tarim River Basin in Xinjiang of China

Water resources are the root of life and development in arid areas like the Xinjiang Autonomous Region of China. In the Tarim Basin in Xinjiang, one of the driest places in the world, melting glaciers are the exclusive water source. Population growth, in particular in-migration, has greatly changed the ecological conditions of the Tarim River Basin in the past 2,500 years. Our research aims to study the interactions between population growth and changes in water and land resources, crossing the boundaries of the different reaches in the Tarim River Basin over the past 50 years. Time series data on population changes and economic development, water volume and quality, land use and land cover changes, and prevalence of morbidity relevant to water quality are collected to study the relationship between these factors. Adopting a statistical analysis and systems dynamics approach, we quantify the effect of population growth on water use and land degradation. ¹This paper results from the research project “Population changes and land degradation in Xinjiang of China,” funded by the Wellcome Trust Foundation (grant no. 065867). The authors appreciate the comments from the anonymous reviewers, and wish to extend thanks to the Asian MetaCentre for Population and Sustainable Development Analysis, and to Warren Sanderson, Wolfgang Lutz, Brenda Yeoh, Vipan Prachuabmoh, Min Weifang, Zheng Xiaoying, Brian O’Neill, Steve Hamburg, Laura Sadovnikoff, Verene Koh, and Sam Balakrishnan, for their invaluable support and help.     

The Effect of Urbanization on China’s Fertility

The relationship between urbanization and fertility decline is known to be inverse in developed countries. However, the nature of this relationship in developing countries that already have relatively low fertilities is not well-understood. This study aims to illustrate how much urbanization contributed to China’s fertility decline between 1982 and 2008 and forecasts how much it can contribute to future reductions in fertility. The study examines changes in the total fertility rate (TFR) at both the national and provincial levels, given regional differences in the urbanization rate. The results show that changes in rural fertility behavior accounted for most of the decline in the national TFR between 1982 and 2008. This finding suggests that official birth control policies were instrumental in curbing China’s population growth. However, urbanization was responsible for about 22% of the decrease in TFR during this period, and its effect was especially important during the latter years (2001–2008). In most provinces, urbanization associated with a decline in provincial-level fertility. The forecasts indicate that urbanization will become the primary factor behind future declines in national fertility. Given the negative effect of urbanization on the TFR, it is possible to relax the one-child policy without having adverse implications for population growth.     

Can Knowledge Improve Population Forecasts at Subcounty Levels?

Recent developments in urban and regional planning require more accurate population forecasts at subcounty levels, as well as a consideration of interactions among population growth, traffic flow, land use, and environmental impacts. However, the extrapolation methods, currently the most often used demographic forecasting techniques for subcounty areas, cannot meet the demand. This study tests a knowledge-based regression approach, which has been successfully used for forecasts at the national level, for subcounty population forecasting. In particular, this study applies four regression models that incorporate demographic characteristics, socioeconomic conditions, transportation accessibility, natural amenities, and land development to examine the population change since 1970 and to prepare the 1990-based forecast of year 2000 population at the minor civil division level in Wisconsin. The findings indicate that this approach does not outperform the extrapolation projections. Although the regression methods produce more precise projections, the least biased projections are often generated by one of the extrapolation techniques. The performance of the knowledge-based regression methods is discounted at subcounty levels by temporal instability and the scale effect. The regression coefficients exhibit a statistically significant level of temporal instability across the estimation and projection periods and tend to change more rapidly at finer geographic scales.     

On Nonstable and Stable Population Momentum

This article decomposes total population momentum into two constituent and multiplicative parts: “nonstable” momentum and “stable” momentum. Nonstable momentum depends on deviations between a population’s current age distribution and its implied stable age distribution. Stable momentum is a function of deviations between a population’s implied stable and stationary age distributions. In general, the factorization of total momentum into the product of nonstable and stable momentum is a very good approximation. The factorization is exact, however, when the current age distribution is stable or when observed fertility is already at replacement. We provide numerical illustrations by calculating nonstable, stable, and total momentum for 176 countries, the world, and its major regions. In short, the article brings together disparate strands of the population momentum literature and shows how the various kinds of momentum fit together into a single unifying framework.     

Southeast Asian urbanization and the growth of mega-urban regions

Southeast Asia has not been sufficiently urbanized long enough to have developed a real urban proletariat, yet it has been profoundly affected by urbanization. An important development has been the emergence of extended metropolitan regions, which now contain about 11 per cent of Southeast Asia’s population. In studying the dynamics of growth of these extended regions, it is important to designate zones around the official metropolitan areas. When this is done for the Southeast Asian mega-urban regions, they are the zones immediately outside the metropolitan area where urban expansion is marked, in-migration greatest, and occupational change most rapid. A corollary of this is that the conclusion frequently drawn that Asian big-city growth is slowing is misleading, because studies usually fail to include the rapidly-growing areas outside metropolitan boundaries. Trends over the 1990–2000 period for Jakarta and Bangkok illustrate the point. Realistic appraisal of the planning needs of Southeast Asia’s mega-urban regions requires integrated research on the broader metropolitan region surrounding the metropolis proper.     

Population dynamics of the green leafhopper,Nephotettix virescens Distant (Hemiptera: Cicadellidae) in synchronized and staggered transplanting areas of paddy fileds in Indonesia

Summary The population dynamics ofNephotettix virescens, a vector of rice tungro virus disease was investigated in a synchronized transplanting area at Jatisari (1984–1986), West Java and in a staggered transplanting area at Sidan (1986–1988), Bali, Indonesia. The FARMCOP suction sampler was employed for population censuses ofN. virescens and its natural enemies. The population growth pattern was affected by transplanting pattern: In the staggered transplanting area, the population density increased from the immigrant generation to the first generation, and sharply decrease thereafter, while in the synchronized transplanting area the population density often reached the highest peak in the second generation. The degree of contageousness in the spatial distribution ofN. virescens was negatively correlated with population density of the immigrant generation. Contribution from Indonesia-Japan Joint Program on Food Crop Protection     

中国西部民族地区的人口生育与死亡状况浅析

西部民族地区包括中国少数民族人口最集中的8个省区,少数民族人口占全国少数民族人口的63.41%。受到这些地区本身历史的、自然的、民族的、以及社会经济发展水平等多种因素影响,其人口状况也表现为与中国中、东部很大的不同,具有自身显著的独特性。本文通过对历次人口普查资料和有关统计数据的分析,对中国西部民族地区的人口变动以及自然增长状况进行了系统地分析,得出了一些有意义的结论。     

Fertility beyond the frontier: indigenous women,fertility, and reproductive practices in the Ecuadorian Amazon

Recent research suggests that after decades of population decline, indigenous populations of the lowland tropics of Latin America are now experiencing rapid growth. At the same time, conservationists have pronounced indigenous lands as a key to the future of Amazon forests. As such, conservationists should have a good understanding of indigenous demography and impacts on conservation and development. Yet, there is little depth to understanding of these demographic changes and a dearth of quantitative research on the reproductive practices of indigenous populations. This study addresses these gaps through analyses of a household survey of 648 women of reproductive age from five distinct ethnic populations in the Ecuadorian Amazon. We estimate fertility, analyze reproductive intentions and contraceptive use, and determine the unmet need for reproductive health services. The analyses confirm high fertility rates and high levels of unmet need for contraception. With regard to program and policy implications, we conclude by arguing that isolation and cultural barriers present unique challenges to meet the reproductive health needs of these populations. Innovative approaches, such as those merging population–health–environment topics, may be most relevant for meeting these challenges.

Residential expansion as a continental threat to U.S. coastal ecosystems

Spatially extensive analysis of satellite, climate, and census data reveals human-environment interactions of regional or continental concern in the United States. A grid-based principal components analysis of Bureau of Census variables revealed two independent demographic phenomena, α-settlement reflecting traditional human settlement patterns and β-settlement describing relative population growth correlated with recent construction in non-agricultural areas, notably in coastal, desert, and “recreational” counties and around expanding metropolitan areas. Regression tree analysis showed that β-settlement was differentially associated with five distinct combinations of seasonality, summer heat or cool, intensity of agriculture, and extent of “barren” land. Beta-settlement was greatest in coastal and desert areas, and coincided with national concentrations of threatened and endangered species.     

The Use of Common Area <Emphasis Type="Italic">k</Emphasis>-Sample Test in Evaluating Targeting Methodologies: An Application to the Case of Egypt

The quality of life (QOL) is a measure of social wellbeing and life satisfaction of individuals in an area. Measuring its spatial dynamics is of great significance as it can assist the policy makers and practitioners in improving the balance between urbanization and living environment. This study proposes an approach to spatially map and examine the relationships between QOL, land use/land cover (LULC) and population density in an urban environment. The city of Lahore, Pakistan was selected as the case study area. The QOL was evaluated through the data related to physical health, psychological, social relationships, environment (natural and built), economic condition and development, and access to facilities and services. The weights/relative importance of each QOL domain was determined through the analytic hierarchy process by processing the data collected from local field experts. Overall QOL was computed by applying the domain weights to the data; spatial mapping of QOL domains and overall QOL was conducted afterwards. The spatial dynamics of QOL were examined, and its interrelationships with LULC and population density were analyzed. The relationship between these three variables turned out to be spatially dynamic. The proposed approach assists the spatial mapping and analyses of QOL, LULC and population, and by examining the spatial dynamics of these variables, contributes to devising appropriate land management and QOL improvement strategies and policies in the metropolitan regions.     

Four theories of population change and the environment

Conclusion It is clear from the discussion of the four principal frameworks used to study population and land use that there is no consensus on the relationship. Most of the debate has centered on the two rivalpolicies of the neoclassical economists and the classical economists or natural scientists. Consensus has been difficult to reach mainly because the empirical evidence is weak and inconclusive, and the diverse experiences of different regions make it difficult to generalize for policy. Because the linkage is unclear, it seems premature to conclude that curbing population growth is the only or most important remedy for land degradation.It is relevant to note that this paper has focussed only on land degradation. It may be that population change plays a more conclusive role in affecting other aspects of the environment.The National Research Council is the operating arm of the National Academy of Sciences. The views expressed in this paper are solely those of the author.     

Vulnerabilities and risks in population and environment studies

In the study of risks , different sciences use the same category in different ways, each related to its own ontological assumptions. But many of these fields communicate very little with one another. This article seeks to approximate two of these areas of study that have shown similar concerns and that can mutually strengthen one another, namely, geography and demography. Geography was one of the first disciplines to include risk in its environmental dimension and has had broad experience in simultaneously focusing on social and natural dynamics. Demography, on the other hand, faces greater difficulties because only recently has it incorporated the environmental dimension into its scientific scope. Both have brought the concept of vulnerability into their conceptual framework as complementary to that of risk. Geographers understand vulnerability as a more symbiotic form of the relationship between society and nature, whereas demographers give it a strong socioeconomic component. In this regard, the conceptual discussion on risks and vulnerabilities, in its attempt at approximating these two fields, is a way of conceptually advancing and strengthening the different approaches to empirical work, especially in population–environment studies which is the common ground for the dialogue between the two disciplines.

Population dynamics of the whitebacked planthopper,Sogatella furcifera (Hemiptera: Delphacidae) with special reference to the relationship between its population growth and the growth stage of rice plants

A population census was conducted to describe the effects of the growth stage of rice on the population dynamics ofS. furcifera, in particular, on immigration, seasonal abundance, population growth rate, and wing-form expression. The number of immigrants was highest on rice plants 17 to 30 days after transplanting (DAT), which suggested that immigrants prefer to settle or remain more on rice plants at the tillering stage (approximately 20–30 DAT). Population growth rate from immigration to the 1st generation decreased with an increase in rice plant age. In contrast, population growth rate from the 1st to 2nd generation was not influenced by rice plant age and was negatively density-dependent. The percentage of macropters (flyers) was positively related to the growth stage of rice when rice was in the vegetative or early part of the reproductive stage, and reached 100% at about 10 days before heading (booting stage). Threafter, most adult females molted into macropters regardless of population density. The roles of host plant age and crowding effect on the population dynamics ofS. furcifera are discussed.     

Farm Dependence and Population Change in China

The existing literature has documented a negative association between farm dependence and population change in Western countries. Theories have also been proposed to explain such a negative association. Whether prior findings based on the western social context can be generalized to less developed countries, such as China, has largely eluded researchers. Using five waves of Chinese Census data and data from China’s Statistical Yearbooks, I investigate the dynamics between farm dependence and population change, particularly, in counties of Chinese provinces that are highly dependent on farms. I find that after controlling for mechanization, nonfarm industries and the human ecological factors that are rooted in the theoretical explanations of rural population change, high farm dependence does not necessarily lead to a lower population growth. The results imply that the existing theories on farm dependence and population change may need to be modified when being applied to less developed regions. The regional variation approach is proposed to understand population change in high-farm-dependent areas of China.     

Age-structure,urbanization, and climate change in developed countries: revisiting STIRPAT for disaggregated population and consumption-related environmental impacts

We focus on three environmental impacts particularly influenced by population age-structure—carbon emissions from transport and residential energy and electricity consumption—as well as aggregate carbon emissions for a panel of developed countries, and take as our starting point the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) framework. Among our contributions is to further disaggregate population into three particularly key age groups: 20–34, 35–49, and 50–64, and by doing so demonstrate that population’s environmental impact differs considerably across age groups, with the older age groups (ones typically associated with larger households) actually exerting a negative influence. Furthermore, those age-specific population influences are different (in absolute and relative terms) for the different environmental impacts we analyze. Also, we find that urbanization, in developed countries, best measures access to a country’s power grid, and thus, is positively associated with energy consumption in the residential sector. Finally, we suggest some modeling and methodological improvements to the STIRPAT framework.     

On the contribution of sectoral natural population growth to the aggregate poverty change

This note extends the Ravallion and Huppi (World Bank Econ Rev 5(1):57–82, 1991) aggregate poverty change decomposition to account for the distinct contribution of migration and differential natural population growth between sectors to the aggregate poverty change. We apply our decomposition to three Least Developing countries. We find that accounting for sectoral difference in natural population growth has a considerable impact on national poverty change. Responsible editor: Alessandro Cigno