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An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts. [ABSTRACT FROM AUTHOR]

Ixodid ticks are acknowledged as one of the most important hematophagous arthropods because of their ability in transmitting a variety of tick-borne diseases. Mathematical models have been developed, based on emerging knowledge about tick ecology, pathogen epidemiology and their interface, to understand tick population dynamics and tick-borne diseases spread patterns. However, no serious effort has been made to model and assess the impact of host immunity triggered by tick feeding on the distribution of the tick population according to tick stages and on tick population extinction and persistence. Here, we construct a novel mathematical model taking into account the effect of host immunity status on tick population dynamics, and analyze the long-term behaviours of the model solutions. Two threshold values, R 11 and R 22 , are introduced to measure the reproduction ratios for the tick-host interaction in the absence and presence of host immunity. We then show that these two thresholds (sometimes under additional conditions) can be used to predict whether the tick population goes extinct ( R 11 < 1 ) and the tick population grows without bound ( R 22 > 1 ). We also prove tick permanence (persistence and boundedness of the tick population) and the existence of a tick persistence equilibrium if R 22 < 1 < R 11 . As the host species adjust their immunity to tick infestation levels, they form for the tick population an environment with a carrying capacity very much like that in logistic growth. Numerical results show that the host immune reactions decrease the size of the tick population at equilibrium and apparently reduce the tick-borne infection risk. [ABSTRACT FROM AUTHOR]

Résumé On étudie le taux d’extinction d’une population modélisée par un processus de branchement à plusieurs types en temps continu dans un environnement aléatoire. Des calculs numériques dans un exemple particulier inspiré d’un modèle épidémique suggèrent une formule explicite pour ce taux d’extinction, mais seulement pour certaines valeurs des paramètres. This study focuses on the extinction rate of a population that follows a continuous-time multi-type branching process in a random environment. Numerical computations in a particular example inspired by an epidemic model suggest an explicit formula for this extinction rate, but only for certain parameter values. [ABSTRACT FROM AUTHOR]

The article analyzes the dynamics of population mortality rates during Uzbekistan's independence. The mortality rates and the mortality rates for some reasons were analyzed nationally. [ABSTRACT FROM AUTHOR]

Studying the impacts of PM2.5 concentrations is critical due to health risks associated with PM2.5. This study analyses 2001-2010 provincial panel data of population-weighted PM2.5 exposure and its main sources in China to identify any correlations that may exist. The results show that energy consumption, highway length, and construction positively affect population-weighted PM2.5 exposure, but vehicle possession has a negative effect. Increasing energy consumption, highway length, and construction areas by 1% resulted in 0.11%, 0.12%, and 0.06% increases to PM2.5 population exposure, respectively. However, when vehicle possession increased by 1%, population exposure to PM2.5 decreased by 0.20%. Highway length may be a very important factor for the increased PM2.5 concentrations in China. Therefore, China should consider national and provincial factors when developing policies to control PM2.5 emissions. [ABSTRACT FROM AUTHOR]

Climate change and human population growth threaten the supply of fresh water for human use and freshwater biodiversity. Long-term studies are necessary to identify the effects of such temporal trends on biological and ecological phenomena; however, the collection of long-term data can be costly and time-consuming., We investigated the effect of hydrological variation over time on population dynamics in a perennial river of the northern Chihuahuan Desert, using an imperilled freshwater mussel ( Popenaias popeii) as a model. We conducted a 15-year mark-and-recapture study, and distance sampling, to estimate demographic parameters while accounting for habitat heterogeneity and changes in river discharge., Recapture probability varied between microhabitats, and survival was positively correlated with river discharge. Survival and the finite rate of population growth were relatively stable over time. Over 60% of individuals were found at relatively high density in riffle habitats, which compose c. 16% of the total study area., Mean monthly temperature in the region increased over the past 100 years, and mean monthly discharge of the Black River declined over the past 65 years. With no significant trends in total monthly precipitation, declines in discharge suggest that reduction of stream flow is likely due to lowering of the water table and decreased groundwater recharge., Significant changes in climate and hydrological regimes, and increases in anthropogenic threats (increased water demand, degraded water quality) in the region, may induce significant declines in population size of this imperilled mussel. We demonstrated the importance of considering habitat heterogeneity and hydrological cycles over time to examine population dynamics. Survival of benthic invertebrates in desert streams is sensitive to hydrological cycles, which are expected to be altered via climate change and extensive water use. Species recovery plans need to incorporate knowledge of spatial distributions when designing strategies for habitat assessment and making conservation decisions. [ABSTRACT FROM AUTHOR]

The causes and consequences of demographic changes for the environment, and the possible ways of influencing population dynamics to achieve 'sustainability', have been the subject of many debates in science and policy in recent decades. However, the body of knowledge concerning relationships between population dynamics and sustainability is quite fragmented, dispersed over many disciplines, and encompasses diverse theories, paradigms and methodologies. This paper reviews four selected frameworks: linear, multiplicative, mediated, and system-theoretical approaches and perspectives. We represent how population-environment relationships are conceptualized, provide examples of research questions and accepted approaches, and critically assess their utility for different sorts of research for sustainable development. We note the growing recognition of the value of embracing complexity in population-environment research, and how this is consistent with normative aims of development. [ABSTRACT FROM AUTHOR]

The colour of environmental variability influences the size of population fluctuations when filtered through density dependent dynamics, driving extinction risk through dynamical resonance. Slow fluctuations (low frequencies) dominate in red environments, rapid fluctuations (high frequencies) in blue environments and white environments are purely random (no frequencies dominate). Two methods are commonly employed to generate the coloured spatial and/or temporal stochastic (environmental) series used in combination with population (dynamical feedback) models: autoregressive [AR(1)] and sinusoidal (1/f) models. We show that changing environmental colour from white to red with 1/f models, and from white to red or blue with AR(1) models, generates coloured environmental series that are not normally distributed at finite time-scales, potentially confounding comparison with normally distributed white noise models. Increasing variability of sample Skewness and Kurtosis and decreasing mean Kurtosis of these series alter the frequency distribution shape of the realised values of the coloured stochastic processes. These changes in distribution shape alter patterns in the probability of single and series of extreme conditions. We show that the reduced extinction risk for undercompensating (slow growing) populations in red environments previously predicted with traditional 1/f methods is an artefact of changes in the distribution shapes of the environmental series. This is demonstrated by comparison with coloured series controlled to be normally distributed using spectral mimicry. Changes in the distribution shape that arise using traditional methods lead to underestimation of extinction risk in normally distributed, red 1/f environments. AR(1) methods also underestimate extinction risks in traditionally generated red environments. This work synthesises previous results and provides further insight into the processes driving extinction risk in model populations. We must let the characteristics of known natural environmental covariates (e.g., colour and distribution shape) guide us in our choice of how to best model the impact of coloured environmental variation on population dynamics. [ABSTRACT FROM AUTHOR]

The article discusses tropical deforestation in Central and South America as of January 2013, with a focus on how rural frontier population dynamics, human migration behaviors, and patterns of tropical land use are driving deforestation. Topics include estimates of population growth in urban regions of developing countries, colonization of land by smallholder farmer migrants, and fertility rates in South America. Additional information is presented on soy bean cultivation, biodiversity in old-growth forests in the Amazon River Valley, and forest management practices.

Studies on the effects of natural and anthropogenic factors on the red deer ( C. elaphus maral) population have been performed in the Caucasian Reserve. The results show that the population is well adapted to the impact of limiting environmental factors, such as high-snow winters and predation by wolves, but its dynamics are highly dependent on anthropogenic factors, primarily poaching. It is concluded that current biotechnical measures are inefficient and that economic activities and protective services in the reserve need optimization. [ABSTRACT FROM AUTHOR]

demoniche is a freely available R-package which simulates stochastic population dynamics in multiple populations of a species. A demographic model projects population sizes utilizing several transition matrices that can represent impacts on species growth. The demoniche model offers options for setting demographic stochasticity, carrying capacity, and dispersal. The demographic projection in each population is linked to spatially-explicit niche values, which affect the species growth. With the demoniche package it is possible to compare the influence of scenarios of environmental changes on future population sizes, extinction probabilities, and range shifts of species. [ABSTRACT FROM AUTHOR]

Rapid growth and globalization of the domestic economy have dramatically accelerated urbanization in China, resulting in significant environmental impacts and challenges for sustainable development. Using a multistate model accounting for distributional aspects of age, sex, education, and migration in rural and urban regions, we estimate the magnitude of urbanization in China through 2030 and examine some major associated sustainability issues. Results indicate that: (1) for a range of assumptions, China's urban population will nearly double from 2000 to 2030; (2) the labor force will constitute a larger share of total population in urban areas than rural due to internal migration of younger workers-this appears particularly true for the mega-urban metropolises of Beijing and Shanghai; (3) rural populations will experience more aging than urban; and (4) level of education among China's rural labor force will remain low, which could pressure China's industrial structural transition from an agricultural to a service-based economy. [ABSTRACT FROM AUTHOR]

Prehistoric hunter-gatherer population size is often assumed to follow climatic and other environmental forcings that affect environmental productivity and the availability of food for human foragers. We tested this assumption by studying the co-variation of archaeological and palaeoenvironmental records during the Holocene in eastern Fennoscandia. The reconstruction of population history is based on the summed probability distribution of archaeological radiocarbon dates, and environmental changes are tracked with locally available, high-resolution biological and physical proxies that are relevant in terms of hunter-gatherer food availability and population dynamics. The results show major population growth during the period of high summer temperature and high productivity of the terrestrial, lacustrine and marine ecosystems that occurred during 7500–5700 cal. yr BP. The growth was followed by an abrupt decline during 5500–4000 cal. yr BP correlating with the onset of late-Holocene cooling and a major forest ecosystem change brought about by the expansion of Norway spruce and the associated change from species-rich mixed forests to a conifer-dominated boreal ecosystem. Forest ecosystem changes likely enforced the negative effects of decreasing productivity on hunter-gatherer food availability. The link between population and environmental proxies breaks down along with the intensification of agriculture after 3500 cal. yr BP, which indicates that agriculture weakened the environmental forcing on long-term human population dynamics. [ABSTRACT FROM AUTHOR]

The typical framework for assessing human population distribution is across a flat, two-dimensional landscape. We alter this perspective by examining population distribution with respect to a third dimension, elevation. This alternative framework, termed hypsographic demography, conceptually provides a more complete visualization and understanding of population distribution. We apply hypsographic demography to North Carolina from the scale of the entire state to streams of different sizes. At the state scale, elevation and population are generally inversely correlated. The flat coastal plain contains the majority of the population at low elevations, whereas higher elevations contain smaller populations due to steep topography, which limits development. At the county scale, the historic location and expansion of cities was more closely correlated with observed patterns of hypsographic demography than elevation or topography. At the scale of the stream, the influence of topography on hypsographic demographics gains importance where topography limits the land available to develop. We use this approach to illustrate how changing the perspective for viewing population distribution can be applied to floodplain policy. [ABSTRACT FROM PUBLISHER]

Explosive population growth and increasing demand for rural homes and lifestyles fueled exurbanization and urbanization in the western USA over the past decades. Using National Land Cover Data we analyzed land fragmentation trends from 1992 to 2001 in five southwestern cities associated with Long Term Ecological Research (LTER) sites. We observed two general fragmentation trends: expansion of the urbanized area leading to fragmentation in the exurban and peri-urban regions and decreased fragmentation associated with infill in the previously developed urban areas. We identified three fragmentation patterns, riparian, polycentric, and monocentric, that reflect the recent western experience with growth and urbanization. From the literature and local expert opinion, we identified five relevant drivers - water provisioning, population dynamics, transportation, topography, and institutions - that shape land use decision-making and fragmentation in the southwest. In order to assess the relative importance of each driver on urbanization, we linked historical site-specific driver information obtained through literature reviews and archival analyses to the observed fragmentation patterns. Our work highlights the importance of understanding land use decision-making drivers in concert and throughout time, as historic decisions leave legacies on landscapes that continue to affect land form and function, a process often forgotten in a region and era of blinding change. [ABSTRACT FROM AUTHOR]

Application of population-based theoretical models to the study of real world populations requires the relationship between the real and theoretical populations to be defined. Otherwise, it is not possible to take a representative field sample or census of a population. I demonstrate that the concept of a biological population is based on a circular definition and is logically untenable. A population is composed of a number of individuals whose membership of the population is determined by their relationship to the rest of the population. This has serious implications for common practice in a range of ecological and evolutionary disciplines. [ABSTRACT FROM AUTHOR]

The interactions between human population dynamics and the environment have often been viewed mechanistically. This review elucidates the complexities and contextual specificities of population-environment relationships in a number of domains. It explores the ways in which demographers and other social scientists have sought to understand the relationships among a full range of population dynamics (e.g., population size, growth, density age and sex composition, migration, urbanization, vital rates) and environmental changes. The chapter briefly reviews a number of the theories for understanding population and the environment and then proceeds to provide a state-of-the-art review of studies that have examined population dynamics and their relationship to five environmental issue areas. The review concludes by relating population-environment research to emerging work on human-environment systems. [ABSTRACT FROM AUTHOR]

The article reports on how the changing population dynamics of the human species as well as those of other species affect the Earth's environment. Using physics, the author attempts to determine the impact populations have on the environment, taking into consideration the ecosystem's reaction to various biological processes. INSETS: CLASSICAL NOISE: POISSON PROCESSES AND VARIABILITY;THE LOWER COLUMBIA RIVER AND ESTUARY ECOSYSTEM;SEPARATE EXOGENOUS AND ENDOGENOUS VARIATION.

The article presents a dynamical approach for evaluating risk in natural resource management. The writers emphasized that understanding risks that originate from various management decisions has been an important consideration towards addressing natural resources depletion. They outlined an approach aimed at determining the ability of several dynamical signatures that will characterize time-series data, like the investigation on the natural population condition and its rates of occurrence. They also discussed ecological factors like climate variability and changing population age structure which affected natural population dynamics.

Recent advances in stochastic demography provide unique insights into the probable effects of increasing environmental variability on population dynamics, and these insights can be substantially different compared with those from deterministic models. Stochastic variation in structured population models influences estimates of population growth rate, persistence and resilience, which ultimately can alter community composition, species interactions, distributions and harvesting. Here, we discuss how understanding these demographic consequences of environmental variation will have applications for anticipating changes in populations resulting from anthropogenic activities that affect the variance in vital rates. We also highlight new tools for anticipating the consequences of the magnitude and temporal patterning of environmental variability. [Copyright &y& Elsevier]

The article discusses the impact of immigration to the U.S. on the environment, and its relationship to other serious demographic issues facing the country and the world. There is broad agreement among scientists that human population dynamics have significant effects on the environment at multiple scales, and that the location, density, and movement of population is related to a variety of conservation and environmental impacts. On the political side, very few people favor either completely closed or completely open borders for the U.S.

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. [ABSTRACT FROM AUTHOR]

Population theory predicts that the reddened environmental noise, especially in combination with high population growth rate, reddens population dynamics, increases population variability and strengthens environment–population correlation. We tested these predictions with axenic populations of ciliated protozoa Tetrahymena thermophila. Populations with low and high growth rate were cultured in a stable environment, and in environments with sublethal temperature fluctuations that had blue, white and red spectra (i.e. negatively autocorrelated, uncorrelated, or positively autocorrelated, respectively). Population size and biomass of individuals were determined at 3-h intervals for 18 days. Dynamics of all populations were reddened, suggesting that internal mechanisms can redden the population spectra. However, population dynamics were reddest, variability highest, and environment–population correlation strongest in the red environment as predicted. Contrary to theoretical predictions and previous empirical findings, population growth rate (rmax being equal to 0.05 and 0.3 h-1 ) had no effect on population dynamics. Mean cell size and variability of cell size were affected by the presence and type of environmental noise suggesting that the physiological consequences of variability depend on colour. Environmental variability decreased mean population size and biomass and the decrease was strongest in rapidly fluctuating blue and white environments. The latter finding implies that rapid fluctuations are physiologically stressful, an effect that is not accounted for in the basic population models. [ABSTRACT FROM AUTHOR]

Abstract Climatic variation associated with the North Atlantic Oscillation (NAO) and El Niño-Southern Oscillation (ENSO) has a widespread influence on the population dynamics of many organisms worldwide. While previous analyses have related the dynamics of northern ungulates to the NAO, there has been no comparable assessment for the species rich assemblages of tropical and subtropical Africa. Census records for 11 ungulate species in South Africa's Kruger National Park over 1977–96 reveal severe population declines by seven species, which were inadequately explained by indices of ENSO or its effects on annual rainfall totals. An additional influence was an extreme reduction in dry season rainfall, concurrent with and perhaps related to a regional temperature rise, possibly a signal of global warming. Boundary fencing now restricts range shifts by such large mammals in response to climatic variation. Our models project near extirpation of three ungulate species from the park's fauna should these climatic conditions recur. [ABSTRACT FROM AUTHOR]

This article presents information on certain disturbing probabilities that could take place in 2000 as speculated in "The Global 2000 Report to the President on Entering the Twenty-First Century," and offers suggestions to tackle the situation. The report has been issued by the U.S. Council on Environmental Quality. The report projects a disturbing picture of population growth, human needs and resource and environmental abuses. It holds that the earth's resources will come under tremendous pressure due to staggering growth of human population and needs. The quality of air will worsen as a consequence of industrial development. The article holds that nations must act urgently in order to prevent such disturbing trends.

The author reflects on the importance of population dynamics on the future of planet Earth. He argues that population growth is linked to almost every challenge confronting humanity, including poverty reduction, urban pollution, and energy production. Topics include inequalities among growth and the standard of living across continents and the difficulties in creating policies that effectively address unsustainable population growth due to regional disparities.