Study Of Population Change Research Articles

Defining fine‐scaled population structure among continuously distributed populations

Abstract Understanding wildlife population structure and connectivity can help managers identify conservation strategies, as structure can facilitate the study of population changes and habitat connectivity can provide information on dispersal and biodiversity. To facilitate the use of wildlife monitoring data for improved adaptive management, we developed a novel approach to define hierarchical tiers (multiple scales) of population structure. We defined population structure by combining graph theory with biological inference about dispersal capability (based on movement, gene flow, and habitat condition) and functional processes affecting movement (e.g. habitat selection across scales of landscape preferences). First, we developed least‐cost paths between high fidelity sites (habitat patches) using a cost surface, informed from functional processes of habitat characteristics to account for resistance of inter‐patch movements. Second, we combined the paths into a multi‐path graph construct. Third, we used information on potential connectivity (dispersal distances) and functional connectivity (permeability of fragmented landscapes based on selection preferences) to decompose the graph into hierarchical tiers of connected subpopulations, denoting the degree that dispersal affected population structure. As a case study, we applied our approach across the greater sage‐grouse (Centrocercus urophasianus) range, a species of conservation concern in western United States. We described the relative importance of local populations and where to potentially avoid landscape disturbances that may negatively affect population connectivity using centrality measures supported by graph theory, and we demonstrated close alignment of the resulting population structure with population densities. This method can be adapted for other species with site fidelity and used as a management tool to evaluate population trends and responses to landscape changes across different temporal and spatial scales.

Vital Registration System in Nepal

The events which are occurring in our life cycle such as birth, death, marriage, divorce and internal migration are the vital events. The vital event registration system is the dynamic study of population changes and it provides the legitimacy of each incident of each individual. Vital statistics generated through civil registration systems are the major source of continuous monitoring of birth, death, marriage, divorce and internal migration over time. The main objective of this study is to find out the annual trend of registration of vital events like birth, death, marriage, divorce and internal migration in Nepal as well as to highlight the need for investment in better registration of all vital events. This article is based on secondary data of nationwide annual vital events statistics obtained from ministry of local development. The number of birth registration has been increased by 2164.39, death by 2301.26, marriage by 3490.75, divorce by 67.09 and internal migration by 2683.68 in each year than preceding year. The registration of all vital events shows the rising trend in Nepal. As many Nepalese are not registering the vital events immediately so concern authorities should come with effective awareness plan to make people aware of importance of registration of vital events in their life as well as to nation.

A LIFE-STAGE APPROACH FOR DECOMPOSING SPATIOTEMPORAL POPULATION CHANGES ALONG AN URBAN-RURAL GRADIENT: IMPLICATIONS FOR REGIONAL PLANNING

abstract The study of population changes across space and time of cohorts at different life stages is relevant for regional planning, but it is often not taken into account. We focus on a case study along the urban-rural gradient of continental Spain from 2002 to 2017 at a municipal scale. Making use of longitudinal data from the municipal registers, we studied changes in total population and three birth cohorts: the cohort joining the workforce, the cohort at a mature working age and the cohort reaching retirement during the study period. The results showed key spatiotemporal population variations. The absolute population increased in 36% of the municipalities, but at least one of the study cohorts showed an increase in 75% of the municipalities. While the cohort joining workforce tended to concentrate in urban and suburban areas, the retiring cohort tended to move to small suburban and rural municipalities. In the next decades the retirement of large birth cohorts in Spain will be a relevant issue for planning. This methodological approach allows us to understand life cycle residential movements across urban, suburban and rural areas and better enables spatial planning decisions. The method can be applied to other study areas at different spatial and temporal scales.

Integrating macro- and micro-level approaches in the explanation of population change

Demographers study population change across time and place, and traditionally they place a strong emphasis on a long-range view of population change. This paper builds on current reflections on how to structure the study of population change and proposes a two-stage perspective. The first stage, discovery, focuses on the production of novel evidence at the population level. The second stage, explanation, develops accounts of demographic change and tests how the action and interaction of individuals generate what is discovered in the first stage. This explanatory stage also provides the foundation for the prediction of demographic change. The transformation of micro-level actions and interactions into macro-level population outcomes is identified as a key challenge for the second stage. Specific instances of research are discussed.

Population regulation in Magellanic penguins: what determines changes in colony size?

Seabirds are often studied at individual colonies, but the confounding effects of emigration and mortality processes in open populations may lead to inappropriate conclusions on the mechanisms underlying population changes. Magellanic penguin (Spheniscus magellanicus) colonies of variable population sizes are distributed along the Argentine coastline. In recent decades, several population and distributional changes have occurred, with some colonies declining and others newly established or increasing. We integrated data of eight colonies scattered along ∼ 600 km in Northern Patagonia (from 41°26´S, 65°01´W to 45°11´S, 66°30´W, Rio Negro and Chubut provinces) and conducted analysis in terms of their growth rates, production of young and of the dependence of those vital rates on colony age, size, and location. We contrasted population trends estimated from abundance data with those derived from population modeling to understand if observed growth rates were attainable under closed population scenarios. Population trends were inversely related to colony size, suggesting a density dependent growth pattern. All colonies located in the north—which were established during the last decades—increased at high rates, with the smallest, recently established colonies growing at the fastest rate. In central-southern Chubut, where colonies are the oldest, the largest breeding aggregations declined, but smaller colonies remained relatively stable. Results provided strong evidence that dispersal played a major role in driving local trends. Breeding success was higher in northern colonies, likely mediated by favorable oceanographic conditions. However, mean foraging distance and body condition of chicks at fledging were influenced by colony size. Recruitment of penguins in the northern area may have been triggered by a combination of density dependence, likely exacerbated by less favorable oceanographic conditions in the southern sector. Our results reaffirm the idea that individual colony trends do not provide confident indicators of population health, highlighting the need to redefine the scale for the study of population changes.

Illusion of a Density-Dependent Effect in Biology

Population changes are believed to be controlled by multiple factors, including an important density-dependent effect. This paper reviews the literature on this topic and shows that this density-dependent effect does not exist. This paper also gives a typical example in which no density-dependent effect was detected in the stock-recruitment relationship in Japanese sardines. The recruitment was found to be determined in proportion to the spawning stock biomass and to be affected by environmental factors. This simple mechanism is applicable not only in fish species but also in insects such as Thrips imaginis in Australia. The reason that many biologists have not become aware that the density-dependent effect does not exist is discussed using a metaphor. This paper proposes a new concept in the study of population change. The new concept proposed here will replace the currently used basic concept that has been assumed to be correct for more than 50 years.

Moses: Planning for the Next Generation

The study of population changes has always been at the centre of public policy and planning. People’s movements, interactions and behaviors will inevitably have an important impact on the society and environment that they are living in. At the same time, such changes will also lead to an evolution of the population itself over time. Advances in technologies and new tools often bring new visions to such studies. To facilitate strategic decision making and to plan developments for a more sustainable future, it is vital to study and understand the changes in our population. This paper introduces Moses, an individual based model that simulates the UK population through discrete demographic processes at a fine spatial scale for 30 years from 2001 to 2031. The modeling method is grounded in a dynamic spatial MicroSimulation Model (MSM), but also introduced Agent Based Model (ABM) insights to strengthen the modeling of movements, interactions and behaviors of distinctively different sub-populations. The MSM can not only produce projections of baseline population with rich information on individuals to facilitate various studies, it can be also useful in providing an assessment of multiple scenarios for different planning applications. In this paper, we will demonstrate three spatial planning applications in the areas of residential land use planning, public health planning and public transport planning. Whilst the demonstrations are deliberately made simple, the contribution of intelligent agents in the modeling of interaction, behavior and the impact of personal histories on demographic changes is clearly shown. Within this framework, it enables researchers to effectively model the heterogeneous decision making units on a large scale, as well as provide the flexibility to introduce different modeling techniques to strengthen various aspects of the model.

Estimating components of population change from census data for incongruent spatial/ temporal units and attributes

When calculating the components of population change over time, the spatial units of analysis must remain constant. However, the boundaries of these units often change from one census to the next Another limiting factor is the absence of data values for the time period. Net migration figures might be available for a five year interval in a census but not for a twenty year interval. GIS and areal interpolation are used here to rectify boundary changes that occur from one census to the next and shift‐share analysis is used to estimate the components of population change from the census data. These methods are applied to a county level study of population change in China between 1982 and 2000.

Validation of Forest Condition Monitoring Programme (ICP-Forests, level 1) cone index scores by measuring cone density using a field-of-view method

A measure of annual cone production is needed for evaluating potential seed crops and for the study of population changes of seed-eating species, but is rarely available in long time series or over extensive areas. The Forest Condition Monitoring (FCM) programme, which contributes to the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP-Forests), has been collecting coning data for Scots pine, Norway spruce and Sitka spruce since 1989, from plots located throughout Britain. A visual assessment system is used to measure a coning index at four levels of abundance as part of the overall crown health assessment. This study tested whether the FCM abundance assessment was related to coning density, and therefore its potential for wider use in future research. Data from the survey have been compared with a field-of-view method that assesses cone density, and the cone production represented by the FCM index has thus been determined. A direct relationship between increased cone index and increased cone density was found; the use of a four-level scoring system allows different cone densities to be distinguished with some reliability. Allocation of cone scores by surveyors from year to year was shown to be consistent except in the case of abundantly coning Sitka spruce. These findings indicate that the FCM programme scoring method does reflect cone production levels and that the data can be used to assess variation in coning between sites and between years. The resolution of the coning data is adequate for assessing the potential for natural regeneration of woodlands but not for selecting stands for seed collections. It is also appropriate for use as a measure of food resource to relate to population changes in seed-eating birds and mammals, and the long-term and Britain-wide nature of these data are of particular value. There is potential for the field-of-view method to be used more widely to evaluate the quality of cone data collected at ICP-Forest sites throughout Europe where the same cone index method has been employed.

INFANT MORTALITY: SOME FAMILY AND COMMUNITY APPROACHES

Family and community historians have played a big part in advancing our understanding of the population history of England in the years prior to the inauguration of the civil registration of births, deaths and marriages in I837. This was, in part due to the main sources being parish registers and census-type listings that were usually locally deposited. For the period since I837, the study of population change, although not population structure as revealed by the census enumerators’ books, has largely shifted from the local community to the registration district and even higher levels of aggregation and has been dominated by scholars wielding sophisticated statistical techniques. The ‘discovery’ of the vaccination birth and infant death registers-virtually copies of the civil birth and death registers-opens the possibility of a new wave of activity for family and community historians for the period I87I-I948, especially in the study of infant mortality.

Challenging Demography: Contributions from Feminist Theory

Demography as a field has made limited progress in its work on understanding the role of gender in demographic change for several reasons. This paper explores the theoretical, methodological, and political influences on this understanding. For example, demography can be seen as a field that because of its stability and resources, has not been forced into the “crises” that might force it to question its assumptions and methodologies; it has not developed a tradition of reflexivity, one which might address alternative approaches to this and other issues, such as the political nature of population work. In addition, partly because of a reliance on certain kinds of methodological approaches, demographers tend to use measures of gender that reflect individual characteristics rather than those that allow understanding of gender at a larger level, or provide information beyond the individual. The result is a particular approach to gender within demographic studies. Feminist theoretical approaches to gender could contribute to the field and the study of population change in general in several key ways.

Racial Attraction or Racial Avoidance in American Suburbs?

The principle of homophily is central to several social-science theories. When applied to the study of population change in geographic areas these theories predict racial homogeneity in residential settlement patterns. The concentration of one group in an area is expected to attract same-group members while deterring others. We examine this prediction using data on 1980-90 population change for four ethnic groups in 1672 U.S. suburban cities. The findings from our analysis contradict the principle of homophily. For example during the 1980s black populations grew faster in those suburbs that had smaller rather than larger percentages of blacks. We explain these findings by spatial-assimilation and place-stratification models. Minority suburbanization is viewed as a process driven primarily by status rather than by ethnic considerations. (EXCERPT)

A Pilot Demographic Study of Population Changes in a Residential Treatment Center

A Pilot Demographic Study of Population Changes in a Residential Treatment Center

Population trends and fluctuations in Swedish woodpeckers

This is a quantitative study of population changes in four non-migratory woodpeckers in Sweden. Data were collected during five periods from late autumn to spring and during the breeding season, mainly using point counts. Most analyses are based on the proportion of the routes (each with 20 points) with observation of the species in each year. From 1975 to 1991 there were no population trends in the Great Spotted and Black Woodpeckers, but decreases in the Green and Lesser Spotted Woodpeckers. The mean annual decrease was about 2% in the Green and 4% in the Lesser Spotted Woodpecker. There was no trend in winter weather over this period, and only for the Black Woodpecker we found associations between mild winters and numbers recorded. The Great Spotted Woodpecker population increased in years with a high spruce seed supply. In southernmost Sweden frequency of observation was higher for the Green and, in winter, for the Black Woodpecker than further north, while the reverse was true for the Great Spotted Woodpecker. No regional difference was found for the Lesser Spotted Woodpecker.

A study of population changes, production and survivorship of river fish: results from a long-term student practical exercise

The paper is presented in the form of a ‘case study’ of the changes in a fish population monitored over a period of several years. Fish from a 100 m section of a drainage canal in Suffolk, England were netted annually by undergraduate students as part of a practical exercise on fish population ecology. Data collected from 1981 to 1987 showed changes in the fish community both in terms of overall abundance (numbers and biomassj and in the relative abundance of different species. A variety of factors including human exploitation of the fish stock, the effect of biotic interactions and climatic conditions are considered as possible influences on fish recruitment and mortality. These possible explanations are examined against the background of other studies which have considered the causes of change in populations of freshwater fish.

A study of population changes in adult Culex quinquefasciatus Say (Diptera: Culicidae) during a mosquito control programme in Dubai, United Arab Emirates.

The effectiveness of insecticidal control measures on adult Culex quinquefasciatus Say in Dubai, United Arab Emirates, was examined. Direct treatment of the study site with cypermethrin applied as a fog caused a temporary reduction both in total numbers (males and females) and in the proportion of older females. When cypermethrin was applied as an ultra low volume formulation at dusk and dawn numbers of males were greatly reduced, but numbers of females were not affected. It appears that the adulticiding operations had little overall effect on the total numbers or survival rate of females, or breeding success. The oviposition cycle duration was estimated to be two days, with the survival rate per oviposition cycle calculated as 30%. With these values it is thought unlikely that filariasis would be transmitted in Dubai.

A Study of Population Changes in the Grasshopper, Zonocerus variegatus, in Southern Nigeria

A Study of Population Changes in the Grasshopper, Zonocerus variegatus, in Southern Nigeria

MIGRATION OF AGRICULTURAL MANPOWER IN SIERRA LEONE

Tijdschrift voor Economische en Sociale GeografieVolume 68, Issue 4 p. 198-210 MIGRATION OF AGRICULTURAL MANPOWER IN SIERRA LEONE JAMES A. S. BLAIR, JAMES A. S. BLAIR Glasgow, U.K. Lecturer, Department of Political Economy, University Glasgow, U.K.Search for more papers by this author JAMES A. S. BLAIR, JAMES A. S. BLAIR Glasgow, U.K. Lecturer, Department of Political Economy, University Glasgow, U.K.Search for more papers by this author First published: August 1977 https://doi.org/10.1111/j.1467-9663.1977.tb01419.xCitations: 1 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume68, Issue4August 1977Pages 198-210 RelatedInformation

Population Changes in Europe Since 1939: a Study of Population Changes in Europe during and since World War 11 as shown by the Balance Sheets of Twenty-four European Countries

Population Changes in Europe Since 1939: a Study of Population Changes in Europe during and since World War 11 as shown by the Balance Sheets of Twenty-four European Countries

Population Changes in Europe Since 1939

Population Changes in Europe since 1939 A Study of Population Changes in Europe during and since World War II as shown by the Balance Sheets of Twenty-four European Countries. By Gregory (Grzegorz) Frumkin. Pp. 191. (London: George Alien and Unwin, Ltd., 1951.) 30s. net.