Patterns Of Population Change Research Articles

EVALUATION OF THE RHIZOBIUM POPULATION OF PIGEONPEA AND COWPEA RHIZOSPHERE AFTER INOCULATION WITH SEVERAL RHIZOBIUM STRAINS

Pigeonpea [Cajanus cajan (L.) Millsp.] and cowpea [Vigna unguiculata (L.) Walp.] seeds were inoculated with broth cultures of Rhizobium strains 3278, 3458, and 3472 at a population of ≈9.5 × 10 g viable cells/ml. They were planted at three air temperature regimes: 20/10C, 30/20C, and 38/25C (day/night), which generated variable rhizosphere temperatures of 17/6C, 26/15C, and 33/20C, respectively. Seeds and/or seedling roots were sampled at 3, 7, 11, and 15 days after planting and Rhizobium survival was enumerated as viable cells on agar media. Only strain 3458 in association with pigeonpea genotype ICPL8304 had a higher population at day 15 than that at the earlier sample dates. The duration of the strains in the rhizosphere, rather than temperature, influenced population changes. No strain showed a consistent increase in cell numbers from inoculation to 15 days after planting. There was no clear pattern of population changes for any strain within or across temperatures, hence it was difficult to identify any strain as having superior growth habits over another.

Spatial changes in invertebrate predation rate in winter wheat following treatment with dimethoate

AbstractExperiments were conducted in 1989 and 1990 to investigate the mechanism underlying patterns of invertebrate population recovery in winter wheat following treatment with the broad‐spectrum insecticide dimethoate. Predation of Drosophila pupae and artificially induced aphid populations was monitored at different distances into plots treated with dimethoate. An initial drop in predation was recorded in all positions following treatment. Predation rate then showed a period of recovery, which progressed from the edge to the centre of the treated plots. This pattern of recovery corresponded to the numerical pattern of recovery of the predatory invertebrate groups; Carabidae, Staphylinidae and Linyphiidae. The results are discussed in terms of mechanisms to explain observed patterns of recovery of invertebrate ‘prey’ groups such as aphids. It is concluded that the ranking of pesticides by their toxicity alone would fail to take into account ecological processes that determine the different patterns of population change following treatment.

Monitoring mohua (yellowhead) populations in the South Island, New Zealand, 1983–93

Abstract The mohua (or yellowhead, Mohoua ochrocephala) is an endangered hole‐nesting passerine which is now absent from >75% of its former range. This paper describes an 11 year monitoring programme, which was set up to survey 14 populations at 12 key sites throughout the range of the mohua, in order to document the pattern of population change and provide early warning of likely local extinctions. Between 1983 and 1993, one mohua population became extinct. Five of the 14 populations declined significantly, and three of these were on the verge of extinction by 1993. One population increased, and seven did not change significantly, although a declining trend was recorded at five of these. Six population crashes coincided with irruptions of stoats (Mustela erminea) following heavy beech (Nothofagus) seeding.

A New Phase of Urban Development in Western Europe? The Evidence for the 1980s

This is the first report of patterns of population change during the 1980s in the major urban regions of the European Union (of 12), using the results of the 1990 census round (or registration data where no census was taken). There is evidence of a substantial breakup of the previous regular pattern of decentralisation, which had been spreading from northern to southern European cities and from the largest to the medium-sized cities. During the 1980s there was a significant degree of recentralisation in many northern European cities, with nearly half of all core cities gaining population. The evidence presented here is consistent with arguments advanced in an earlier paper which suggested that such a change of patterns should be anticipated. There does not appear to be a complete reversal of previous patterns, however. Some urban regions continue to decentralise and decline; others are declining but experiencing relative recentralisation. The pattern is that there is now a greater variation in patterns. Cities which are experiencing the most relative recentralisation show that they are not a random group. They have characteristics consistent with the causal analysis which is presented. The plausibility of general, rather than particularistic explanations, is made greater by the very similar change of trends recently reported for US cities.

Sociology: A Brief Introduction

Sociology: A Brief Introduction

The turnaround in Australia: some first observations from the 1991 census.

"The aim of this paper is to utilise recently released census results to examine patterns of population change in non-metropolitan Australia during the 1986-91 period, focusing particularly upon the net migration component of that change. The paper presents an overview of recent trends in population change in non-metropolitan areas and then moves to an analysis of net migration patterns in non-metropolitan local government areas during the late 1980s using a Life Table Survival Ratio technique to estimate net migration. It appears that the trends observed in the early 1980s have continued into the late 1980s and early 1990s, and that overall the 'turnaround' is slowing down and becoming more diversified, more complex, and much less predictable in the 1990s."

Counterurbanization and coastal development in New South Wales

Since the 1960s the pattern of population change in New South Wales has contained a marked growth in coastal regions. This is attributable to residential migration and to employment generated mainly by the expansion of tourism. In explaining the change it is suggested that an appropriate framework exists in the concept of Counterurbanization. A discussion of the concept is followed by a description of trends in New South Wales.

Evidence of Tularemia Regulating a Semi-Isolated Cottontail Rabbit Population

We studied a semi-isolated cottontail rabbit (Sylvilagus floridanus) population in southern Illinois from 1982 to 1990 to determine patterns of population change following a tularemia epizootic in 1980 and to evaluate the role of enzootic disease in population regulation. The population reached a density of > 14 rabbits/ha in the best habitats 7 years after the 1980 epizootic, but drought in summer 1988 and harvest that autumn reduced the population base. Condition indices and necropsy did not indicate food as a limiting factor at the observed peak density. Prior to 1988, serosurveys to detect IgM/IgG immunoglobulins to Francisella tularensis provided the only evidence of enzootic tularemia in the population, but clinical cases were detected beginning April 1988

Phoenix in Flux: Household Instability, Residential Mobility, and Neighborhood Change

Abstract The linkages between household instability and residential mobility underlie patterns of population change in the city. To explicate these linkages in Phoenix, Arizona, a rapidly growing Sunbelt city with high population turnover, we queried a sample of residents about their living arrangements and mobility status from 1986–88. The terms stable and unstable refer to household status; movers and stayers refer to mobility status. Results indicate that there is considerable flux in the Phoenix population. One-third of our respondents experienced a change in household status, a residential move, or both. The rates of mobility for rental housing exceed the rates of household change, resulting in stable moving. Owners, especially those in older neighborhoods, are more likely to change living arrangements than to move, resulting in unstable staying. Mobility exceeds household instability in areas where nonfamilies are disproportionately represented; instability exceeds mobility where families dominate. A map of family versus nonfamily households provides clues to the geographic distribution of stable movers and unstable stayers.

The population dynamics of the large pine aphid, Cinara pinea (Mordv.)

SummaryThe large pine aphid, Cinara pinea lives exclusively on Pinus species, where it feeds on the foliated shoots of the current and previous year. The paper describes the development of a computer model designed to simulate the aphid's population dynamics on saplings in the controlled environment of the laboratory, i.e. in the absence of natural enemies. The model was able to account for about 80% of the variation in aphid numbers within and between trees over a three month period. Sensitivity analysis revealed that the number of pine aphids is limited primarily by nymphal emigration, the operation of which is sensitive both to density and to plant quality as reflected in aphid growth rates. Of secondary importance are changes in reproduction acting through increased reproductive delay, again a result of altered growth rates and adult size. Development, too, has an important secondary influence. Contrary to expectation and conventional belief, however, alate production proved to be of negligible importance, either in limiting or regulating population numbers. Alatae are produced in too few numbers and for too short a period to significantly alter the pattern of population change.

Summer movement patterns of Arctic lemmings (Lemmus sibiricus and Dicrostonyx groenlandicus)

Several measures of movement based on livetrapping data were used to compare summer movement patterns of Lemmus sibiricus and Dicrostonyx groenlandicus in northern Canada. Distances moved by individuals of both species were greater when populations were intermediate in size than at high or low density. At intermediate density, males of both species moved farther than females. Seasonal movement patterns of the two species were similar. Coincident with reproductive periods in late July and late August, distances moved decreased in both species. Increased movements of both species followed periods of reproductive activity and also occurred at the end of each summer. These latter movements are related to seasonal changes in patterns of habitat use and diet in each species. These results suggest that dispersal is an important determinant of seasonal patterns of population change in both L. sibiricus and D. groenlandicus.

Ethno-ideological segregation and metropolitan development

The effect of ethnic residential segregation on metropolitan development and expansion is examined. The ethno-ideologically divided city is an extreme case of segregation and Jerusalem, an example of such a city, provides a good case study. Deviations from patterns of population change predicted by the theory of the urban population density gradient are analysed non-statistically using the available data. When the two ethnic sectors are treated as separate cities, these deviations do not seem to be very important and population change conforms to the model. This seen in the light of local patterns of segregation seems to imply that at the local ‘tactical’ level domination and exclusion of the other group seems to result, whereas on the regional strategic level power is shared more equally and economic and demographic factors play the major role in fashioning the distribution of population change.

Regional economic disparities and population change in Morocco.

"The paper examines patterns of population change in Morocco for the decade 1971-1981. They do not mirror those which might have been expected in view of the national economic and spatial structure of this country. The differences are attributed to international economic forces which have transcended national forces in shaping population patterns in parts of the country."

Recent Patterns of Population Change in Denmark

Recent Patterns of Population Change in Denmark

Problems of cartographic representation of patterns of population change

Problems of cartographic representation of patterns of population change

Problems of cartographic representation of patterns of population change

Abstract Distribution maps of social and economic data are frequently used to diagnose the location of areas, requiring public policy and action. The paper demonstrates, with population data, how mapped patterns can often be the products of the size and shape of the spatial and temporal units chosen by the map compiler. The problem is not appreciated by most policy makers.

Social Structure and Population Change: A Comparative Study of Tokugawa Japan and Ch'ing China

Whenever excessive population has become a problem man throughout history has felt the need to control his numbers (and we cannot doubt that such limitation took place even before recorded history). Today as always it seems that control remains a controversial issue with pro-natalists condemning some or even all control practices and injunctions as immoral or contrary to the national interest. Given an issue as important as this any light that the past can shed on population change should be useful. This paper is a historical inquiry into two disparate patterns of population change and how the differences affected the divergent socioeconomic development of each. The determinants of population change are geographic characteristics the economic environment the state of birth-control technology and the social structure. Rapid changes in the state of technology are recent phenomena; thus for most of human history the technology has been quite primitive. Consequently it is the other three factors that have been of overriding importance. It can be said that the proximate cause of population change is social structure because geographic and economic constraints induce changes in that structure and necessarily have to act through it. We present here the vividly contrasting records on preindustrial change of population in Tokugawa Japan and Ching China. We will argue that social institutions played a crucial role in disposing the Japanese toward population control and the Chinese toward population increase. We believe moreover that certain features of the Tokugawa population change discussed here will throw new light on the economic developments of the Tokugawa period and help to explain the unprecedented rapidity of the post-Tokugawa economic transformation. Our study is limited to the Tokugawa period (1600-1868) in Japan and to the Ching period (1644-1912) in China. (excerpt)

A comparative life historical study of the three heterosomes in Sendai Bay.

Three heterosomes, stone flounder, plaice and dab are distributed over an almost common area on the continental shelfin Sendai Bay and feed on the common food, infauna organisms. Although the stock levels of the former two species have declined under the recent heavy fishing, conversely that of the latter has increased to a high level. These phenomena seem to result from the fact that while both stone flounder and plaice spawn in late autumn-winter, being long-lived, large-sized and low in intrinsic rate of natural increase rm, and reveal a stable pattern of population change, dab spawns in late winter-sping, being short-lived, small-sized and high in rm, and shows a variable pattern of fluctuation in recruitment.

Regional Patterns of Population Change in the Soviet Union 1959-1979

rT HE Soviet Union has undergone tremendous and, at times, traumatic population change. From approximately the beginning of this century through World War II, the country suffered huge population losses from war, revolution, civil war and internal strife, and famine, while major alterations of the economic landscape led to a large-scale geographical redistribution of the population through both interregional and rural-to-urban migration. These demographic trends are well covered elsewhere, and I shall touch on them here only insofar as later events are concerned.' My attention in this article centers on population change in the USSR in the post-World War II era, and I utilize recently published materials from the Soviet census of 1979 and data from the earlier enumerations of 1959 and 1970 which, taken together, allow for both a meaningful longitudinal analysis and an examination of the spatial dimensions of population change.2 Specifically the aspects of population change that will be detailed here are regional population growth and redistribution-both in the aggregate and for the urban and rural components-and urbanization. Beyond the description of these patterns, explanations will be offered to the extent that current concepts and available information allow. Beyond the intrinsic interest of these topics for scholars, the elements of population change in temporal and spatial contexts provide insights into socioeconomic conditions that are the object of government policies. For example, changes in the size and the geographical distribution of the urban population are determined largely by economic factors; this aspect of population change can thus be used to evaluate policies of the Soviet government designed to shape the course of regional economic development. On the other hand, the universal experience with population change indicates that demographic trends not only are passive, that is, determined by other factors, but also are active in the broader social, economic, and political arenas. Hence interregional differentials in the rate of population growth, particularly when these differentials are along ethnic lines, may portend serious problems, as is the case in the USSR. It is therefore important to examine population change in light of policies intended to influence demographic trends directly or indirectly and to suggest likely implications of the trends. In broad overview of the demographic situation in the USSR, the period after World War II is notable for a reversal of earlier trends in regional population redis-

Studies on the Behavior of Wintering Geese

(1) The authors studied the population size and change of wild geese wintering and roosting at Lake Izunuma (Fig.1), Miyagi Pref., northern Honshu, for seven years from 1971 to 1977.Monthly counts of bird number were made at daybreak when flocks of geese fly out of Lake Izunuma to feeding places. In addition, the numbers of geese roosting at the lake or feeding at paddy fields were counted during the daytime 3 to 4 times a month.(2) The wintering geese at Lake Izunuma consist chiefly of the White-fronted Goose (Anser albifrons) and the Bean Goose (A. fabalis). The Lesser White-fronted Goose (A. erythropus), Lesser Snow Goose (A. caerulescens), Aleutian Canada Goose (Branta canadensis leucopareia) and Brent Goose (Branta bernicla) are rare or accidental visitors. In 1972 there were about 3, 000 White-fronted Geese and 200 Bean Geese. In spite of deterioration of the natural environment surrounding Lake Izunuma, they increased to 5, 600 and 1, 400 respectively in the following five years (Fig.4). The reason for the increase of the population of geese may be attributed to the prohibition of hunting of wild geese in Japan in 1971. (3) Seasonal changes of numbers of the wild geese wintering at Lake Izunuma were shown in Figs.3, 5 and 8. In these monthly-peak-number graphs, there are 'cap' and 'two-peak' types (Fig.3). The graph of cap type shows an ordinary pattern of population change of wild geese at Lake Izunuma during one wintering period, i.e., wintering geese arrive in a small number in late September, increase to a large number in October, reach to a peak number in November or December, begin to decrease in late January, and then depart in February or March. The graph of two-peak type indicates that wintering geese take a temporary refuge in the south when paddy fields are covered with thick snow for a period of 30 days or more. They returned to roost at Lake Izunuma when the snow in paddy fields melted.(4) The monthly-peak-number graphs of the White-fronted Goose resemble that of total wintering geese, because the number of White-fronted Geese is 60-80 % of the total goose number.On the contrary, the numbers of Bean Geese increases to a peak in October and then reaches at maximum in December. Against snow, Bean Geese also take refuge in the south but they seem to be more resistant to snow and the extent of movements during the snowy periods is smaller.(5) The wintering geese depart from Lake Izunuma in February or March regularly.In the year when there is not much snow, they usually leave in February and the monthly-peak-number graph becomes a cap type. When there is much snow, they leave in March and the monthly-peak-number graph resulted in a two-peak curve.