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.     

Has the World Really Survived the Population Bomb? (Commentary on “How the World Survived the Population Bomb: Lessons From 50 Years of Extraordinary Demographic History”)

In his PAA presidential address and corresponding article in Demography, David Lam (Demography 48:1231–1262, 2011) documented the extraordinary progress of humankind—vis-à-vis poverty alleviation, increased schooling, and reductions in mortality and fertility—since 1960 and noted that he expects further improvements by 2050. However, although Lam briefly covered the problems of global warming and pollution, he did not address several other major environmental problems that are closely related to the rapid human population growth in recent decades and to the progress he described. This commentary highlights some of these problems to provide a more balanced perspective on the situation of the world. Specifically, humans currently are using resources at an unsustainable level. Groundwater depletion and overuse of river water are major problems on multiple continents. Fossil fuel resources and several minerals are being depleted. Other major problems include deforestation, with the annual forest clearing globally estimated to be an area the size of New York State; and species extinction, with rates estimated to be 100 to 1,000 times higher than background rates. Principles of ecological economics are presented that allow an integration of ecology and economic development and better potential for preservation of the world for future generations.     

The population,agriculture, and environment nexus in Latin America: country-level evidence from the latter half of the twentieth century

Unprecedented population growth and migration accompanied equally unprecedented land use and land cover change in Latin America during the latter decades of the twentieth century. Country-level data are examined with bivariate statistics to determine relationships between changes in population patterns and land use (agriculture and forest cover) from 1961 to 2001. In South America, large forest areas were eliminated during the period, while exceptionally high rates of forest clearing were ubiquitous in the Central America/Caribbean region. These environmental changes accompanied dissimilar initial population densities and different effects of population change on agriculture. While interacting with a host of political, socio-economic, and geographic processes, it appears that both Malthusian and Boserupian demographic processes were important drivers of deforestation. Given continued, though slowing, population growth, increased urban consumption, and future land use constraints, policy makers face myriad challenges in advancing sustainable agriculture-population dynamics in Latin America.     

Family planning and deforestation: evidence from the Ecuadorian Amazon

Despite an abundant literature exploring the relationship between population growth and forest cover change, comparatively little research has examined the forest cover impacts of family planning use—a key determinant of population growth rates in many developing countries. Using data from a panel survey of farms in the Northern Ecuadorian Amazon, this paper explores whether family planning use affects changes in forest cover. After controlling for household life cycle effects, family planning use among female heads of farm households did not have an independent effect on deforestation, reforestation, or net forest loss between 1990 and 2008. Rather, shorter-term drivers of forest change tend to be associated with household life cycles and shifts in production and consumption. However, family planning will continue to improve development and health outcomes for women by reducing unwanted fertility and may offer longer-term environmental benefits.     

Adolescent alienation: Evaluating the hypotheses

Statistics reveal the steady, long-term, increase of self-and-other-destructive conduct among American youths. The conduct involved includes suicide, homicide, out-of-wedlock births, drug abuse and recorded crimes. A variety of hypotheses have been proposed to interpret this conduct — and to indicate possible remedies. Some of these hypotheses are briefly characterized, generally evaluated, and rejected. One hypothesis, the so-called youth bulge theory, suggests that the conduct is due to a disproportinate relationship between the youth population and the adult population; this disproportion — the so-called youth bulge — ultimately led to various modes of youth alienation. The youth bulge hypothesis was tested through a regression analysis which estimated the contemporaneous relationship between a measure of adolescent disorder (the youth suicide rate over time) and the proportion of youths to adults. A statistically significant but small relationship was found between the two variables. The implications of this conclusion are briefly sketched.     

Prehistoric human impact on the environment in the upland North American Southwest

Some early Anasazi (prehistoric Puebloan) agricultural practices tended to be land-extensive and made substantial impact on the forests, primarily through clearing by burning. Later agriculture tended to be more land-intensive, but longer duration occupations by larger populations also had significant local effects on the forests, through both clearing for fields and through intensive harvest of firewood. Strategies of early Anasazi agriculture that resulted in forest depletion probably also tended to maximize the power output of the economic systems, and therefore must have had considerable selective value. Depletion of various wild resources was an important impetus to culture change, leading, in conjunction with population growth, to more intensive farming practices, and contributing to the tendency to aggregate in large villages at various times in the prehistoric period.     

Paperbark and pinard: A historical account of maternity care in one remote Australian Aboriginal town

Background and aimMaternity care in remote areas of the Australian Northern Territory is restricted to antenatal and postnatal care only, with women routinely evacuated to give birth in hospital. Using one remote Aboriginal community as a case study, our aim with this research was to document and explore the major changes to the provision of remote maternity care over the period spanning pre-European colonisation to 1996.MethodsOur research methods included historical ethnographic fieldwork (2007–2013); interviews with Aboriginal women, Aboriginal health workers, religious and non-religious non-Aboriginal health workers and past residents; and archival review of historical documents.FindingsWe identified four distinct eras of maternity care. Maternity care staffed by nuns who were trained in nursing and midwifery serviced childbirth in the local community. Support for community childbirth was incrementally withdrawn over a period, until the government eventually assumed responsibility for all health care.ConclusionsThe introduction of Western maternity care colonised Aboriginal birth practices and midwifery practice. Historical population statistics suggest that access to local Western maternity care may have contributed to a significant population increase. Despite population growth and higher demand for maternity services, local maternity services declined significantly. The rationale for removing childbirth services from the community was never explicitly addressed in any known written policy directive. Declining maternity services led to the de-skilling of many Aboriginal health workers and the significant community loss of future career pathways for Aboriginal midwives. This has contributed to the current status quo, with very few female Aboriginal health workers actively providing remote maternity care.     

Social components of metropolitan population densities

The decline of population density from the center of metropolitan areas can be expressed mathematically as: d _r = d _o e ^gr where d _r is the population density of a subarea at distance r from the center, d _o is the hypothetical density at the center, and g is the population-density gradient, empirically always negative. Expanding this exponential model permits examining systematically the relationship between distance from center and various components of population density—housing-unit density, vacant units, household size, and group-quarters population-and the change over time in these components. For the metropolitan areas of Columbus, Dayton, Hartford, Miami, and Syracuse in 1950 and 1960, housing-unit density decreased from the center more sharply than population density. Vacancies, which increased slightly at the center, were proportionately low in the stable middle zones but somewhat higher in the rapidly growing outer zones. While household size decreased around the center between 1950 and 1960, on the periphery it remained constant or increased slightly because of increased family size. During the same decade, the group-quarters population, relative to total population, shifted outward from the center to the periphery to a small extent.     

Are marriages that cross ethnic boundaries more likely to end in divorce?

According to the most recent Australian census, almost 40 per cent of the population were immigrants or the children of immigrants. They came from a wide range of countries, mainly in Europe or Asia. Earlier census analyses of their marriage patterns in Australia show a declining tendency over time towards inmarriage among most immigrant groups. However, there are potential biases in using retrospective census data to measure changes in inmarriage. For example, marriages that cross ethnic lines may be more likely to end in divorce than ethnically homogeneous marriages. If so, an analysis of marriages surviving to the most recent census will tend to (1)understate past rates of intermarriage and (2)overstate any trend over time towards intermarriage. This paper discusses data on ethnic divorce patterns in Australia since the end of the Second World War and assesses evidence for differential rates of breakdown among ethnically homogeneous versus heterogeneous marriages. Analysis shows that, relative to a cross-pressures model of behavioural convergence, heterogamous marriages are more likely to end in divorce than homogamous ones.     

On the momentum of population growth

If age-specific birth rates drop immediately to the level of bare replacement the ultimate stationary number of a population will be given by (9): $$\left( {{\textstyle{{b\mathop e\limits^ \bullet {}_0} \over {r\mu }}}} \right)\left( {\frac{{R_0 - 1}}{{R_0 }}} \right)$$ multiplied by the present number, where b is the birth rate, r the rate of increase, \(\mathop e\limits^ \bullet _0 \) the expectation of life, and R ₀ the Net Reproduction Rate, all before the drop in fertility, and μ the mean age of childbearing afterwards. This expression is derived in the first place for females on the stable assumption; extension to both sexes is provided, and comparison with real populations shows the numerical error to be small where fertility has not yet started to drop. The result (9) tells how the lower limit of the ultimate population depends on parameters of the existing population, and for values typical of underdeveloped countries works out to about 1. 6. If a delay of 15 years occurs before the drop of the birth rate to replacement the population will multiply by over 2. 5 before attaining stationarity. The ultimate population actually reached will be higher insofar as death rates continue to improve. If stability cannot be assumed the ultimate stationary population is provided by the more general expression (7), which is still easier to calculate than a detailed projection.     

Population and Poverty in Classical Theory: Testing a Structural Model for India

There has for many years been debate over the relationships between population growth rates and poverty. India is a country which provides a good testing ground for hypotheses about this relationship because since Independence a relatively high proportion of the population have lived in poverty; and there also exist reasonable data. This paper develops a simple structural model to investigate the relationship between population growth and poverty in particular, testing a series of hypotheses developed from the work of Marx and Malthus. The data are analysed at state level, and attention is drawn to the problems that this might cause as behaviour is typically determined at the individual household level. The results show that agricultural productivity and the process of landlessness are better predictors of poverty at a state level than the population growth rate. It is argued that the results fit better with the views of Marx than those of Malthus.     

How We Fall Apart: Similarities of Human Aging in 10 European Countries

We analyze human aging—understood as health deficit accumulation—for a panel of European individuals, using four waves of the Survey of Health, Aging and Retirement in Europe (SHARE data set) and constructing a health deficit index. Results from log-linear regressions suggest that, on average, elderly European men and women develop approximately 2.5 % more health deficits from one birthday to the next. In nonlinear regressions (akin to the Gompertz-Makeham model), however, we find much greater rates of aging and large differences between men and women as well as between countries. Interestingly, these differences follow a particular regularity (akin to the compensation effect of mortality) and suggest an age at which average health deficits converge for men and women and across countries. This age, which may be associated with human life span, is estimated as 102 ± 2.6 years.     

Migradollars and mortality: The effects of migration on infant survival in Mexico

We apply multilevel methods to data from Mexico to examine how village migration patterns affect infant survival outcomes in origins. We argue that migration is a cumulative process with varying health effects at different stages of its progression, and test several related hypotheses. Findings suggest higher rates of infant mortality in communities experiencing intense U.S. migration. However, two factors diminish the disruptive effects of migration: migradollars, or migrant remittances to villages, and the institutionalization of migration over time. Mortality risks are low when remittances are high and decrease as migration becomes increasingly salient to livelihoods of communities. Together, the findings indicate eventual benefits to all infants, irrespective of household migration experience, as a result of the development of social and economic processes related to U.S. migration.     

Social indicators of marital instability,U.S.A., 1920–1969

A social indicators model which included demographic variables (birth rate and aged child ratio), economic variable (unemployment) and marriage rates (control variable) was utilized in explaining changes in divorce rates over time. Analysis of time series data for two distinctive periods in the U.S.A. (1920–1940 and 1946–1969) revealed the following significant results:

1. Demographic changes in the age structure of the population while controlling for marriage rates explains significantly larger amounts of the variance in marital instability than economic changes alone (unemployment).
2. In the post-World War II era unemployment was not found to be a statistically significant predictor of marital instability when control for demographic changes were established.
3. In the post-World War II era marriage rates appear to be a significant predictor of divorce rates when control for demographic changes were maintained.
4. In the post-World War II era marriage rates were found to be more sensitive to changes in economic conditions than marital instability (divorce rate).

     

Population growth,changing agricultural practices,and environmental degradation in Zaire

This paper examines linkages between the demographic changes taking place in Zaire, particularly overall population growth and rapid urbanization, changes in agricultural practices, and related environmental degradation. Pressures to feed Zaire's rapidly increasing urban population, which fall on a rural population that has been growing relatively slowly in recent years, as well as population growth and increased population density in certain areas of the country, have resulted in changes in agricultural practices that are described in the paper. These changes in turn are leading to declining soil fertility, deforestation, and degradation of the natural resource base. Given present technology and the state of Zaire's economy, the changes in agricultural practices that have emerged in response to population growth, increased population density, and growth in demand for food production do not appear to be sustainable in the long run.     

Effects of parasitoid community structure upon the population dynamics of the honeysuckle leafminer,Chromatomyia suikazurae (Diptera: Agromyzidae)

Population dynamics of a leafminer,Chromatomyia suikazurae (Agromyzidae, Diptera) and its parasitoid community were studied for ten years at seven natural populations along an altitudinal gradient in Japan. This species which mines leaves of a forest shrub,Lonicera gracilipes (Caprifoliaceae), was attacked by 25 hymenopterous parasitoid species. Annually, the parasitoid community structure varied less within a population than among populations. The seven parasitoid communities were clustered into three groups corresponding to the altitudinal gradient: (a) lowland communities dominated by late-attacking, generalist pupal idiobiont eulophids and with highest species diversity, (b) hillside communities dominated by an early-attacking, specialist larval-pupal koinobiont braconid and (c) highland communities dominated by an early-attacking, generalist larval idiobiont eulophid. Annual changes of the host larval densities among the local populations were largely synchronous rather than cyclic. Among these populations, host density levels and mortality patterns greatly varied. By analyzing these inter-populational differences of host mortality patterns, the following conclusions were drawn: (1) The host mortality patterns were determined by the host utilization patterns of the locally dominant species. (2) The host pupal mortality but not larval mortality was related to species diversity but not to species richness itself of each parasitoid community. (3) Density dependence was detected only in pupal mortality at a lowland population dominated by late-attacking pupal parasitoids. These results suggest that interspecific interactions of parasitoids add additive effects to host population dynamics dissimilarly among local populations with different parasitoid communities.     

Extractive workload: a mixed-method approach for investigating the socially differentiated effects of land-use/land-cover changes in a southern Zambian frontier

In rural regions across the globe, local natural resources (i.e., “bush” resources) are central to meeting daily household needs. Culturally-influenced gender- and age-based divisions of labor guide the harvesting of these resources and, as a result, shifts in resource availability will differentially affect women, men, girls, and boys. This research brief presents results of an innovative pilot project designed to assess the socially differentiated effects of land-use/land-cover changes (LULCC) on Gwembe Tonga migrants living in Kulaale, an agricultural frontier in southern Zambia. Integrating existing analyses of remotely sensed imagery with a seasonal resource survey and mapping exercise (n = 20 homesteads), this study finds the average extractive workloads (mean annual distance traveled for the collection of bush resources) of women, men, girls, and boys to be both unequal and contrary to recent speculations about the distinctive vulnerability of adult women to environmental change. Drawing on qualitative ethnographic methods—including semi-structured interviews (n = 101), a homestead labor survey (n = 38), participant observation, and references to over fifty years of anthropological research—the author identifies additional variables—including the demographic structure of Kulaale homesteads and the flexible division of subsistence labor—that color Gwembe Tonga migrants’ aged and gendered experiences of LULCC. The study adds important nuance to our understanding of natural resource practices and individual-level vulnerability, particularly in the face of contemporary environmental change.     

Tracing the Density Impulse in Rural Settlement Systems: A Quantitative Analysis of the Factors Underlying Rural Population Density Across South-Eastern Australia, 1981–2001

Rural population density has a very significant independent influence over important socio-economic and demographic characteristics of developed world rural communities. Additionally, it is a fundamental variable in public policy and planning, both expressing and influencing the relative cost-efficiency of servicing populations. Yet density is itself produced by more fundamental qualities (e.g. environmental resources, nature and time of colonisation) which may themselves change over time. Treating rural population density as a dependent variable produced by a wide variety of factors, we build and test two causal models that attempt to explain the observed pattern of rural densities across south-eastern Australia (n = 414 communities). We distinguish between a “productivist” model—applicable for most of white Australia’s history—and a consumptionist model that takes account of recent counter-urbanisation trends. These models are applied to the entire study area and, in recognition of the study area’s internal heterogeneity, to five clusters of communities. In the drier inland and remoter zones, the productivist model exhibits the greatest explanatory power, while in the more accessible and well-watered “multifunctional” zones, an expanded model that incorporates a measure of “amenity” produces the best results. The research finds that simple environmental factors, coupled with relative location within the national space economy, act as dominant controls over rural population density in early 21st century Australia.

Asia's demographic future: the next 20 years

Even with the decline of fertility rates in most of Asia, the problem of population growth is still very serious. It is important to stress to Asian leaders and Western researchers that the problem is by no means solved just because fertility rates have declined. In many countries the number of young people is quite substantial and when they increase their numbers, certain problems will develop. Over the next 20 years, urban areas will see a marked increase in population and the resultant problems. Unemployment, increased pollution, and overcrowding will greatly decrease the quality of life for millions of people. This will happen because of natural increases and from the migration of the rural communities. In the rural areas, because of high fertility rates, population will continue to grow in spite of the large numbers of peoples moving to the city. Asia has some of the most densely populated agricultural communities and as their numbers increase, poverty and its associated problem will follow. The solutions to these problems include continued efforts in family planning, maternal and child health, and the improvement of the status of women.