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This paper analyzes the pattern of fluctuations of births in an age-structured population whose growth is subject to environmental or economic constraint. It synthesizes the traditional demographic analysis of age-structured renewal with constant vital rates and the economic analysis which treats population change endogenously. When cohort fertility depends on relative cohort size, or when period fertility depends on labor force size, fluctuations of forty or more years replace the traditional "echo" or generation-length cycle. Twentieth-century U. S. fertility change agrees well with the theory, as the "Easterlin Hypothesis" suggests; but the period model fits better than the cohort model. [ABSTRACT FROM AUTHOR]

This paper, on aquatic snails at Malham Tarn (Grid. ref. 34897666), is concerned with the dispersion patterns of two species-populations of littoral, stone-dwelling gastropods (Ancylus fluviatilis Müll. and Planorbis contortus Linn.) and forms part of a sequence involved with the ecology of this group. It will consider the nature of the patterns observed, and will infer causes, a-posteriori, from correlated distributions in independent environmental variables. This type of information is generally lacking for freshwater, bottom-dwelling invertebrates (Elliott, 1971) and previous reports on the Mollusca have been based on extensive rather than intensive surveys (e.g. Boycott, 1936). The habitat of an organism and consequently its dispersion pattern may be defined at various observational levels, e.g. in the case of the snails in question as: bodies of freshwater; littoral regions; submerged stones; submerged stones of a particular type; a particular part of submerged stones. Clearly the habitat definition chosen will depend on the degree of precision associated with the observations made, and on the type of ecological question being posed. The data presented below are extracted from different levels on such an observational sequence. They begin with a consideration of the overall vertical and lateral patterns of dispersion in the total sampling area and then focus attention on the between- and on-stone patterns respectively. Information on whole-Tarn dispersion patterns has been published elsewhere (Calow, 1973a). [ABSTRACT FROM AUTHOR]

The article discusses the third paper in a series that provide results of studies that describes the site and vegetation which are in many respects typical of miombo woodland in Western Tanzania. It is the author's view that the Forest Reserve has probably not been cultivated for the past 50 years as throughout the miombo, cultivation has certainly occurred at times in the more distant past. It is suggested that the shifting cultivation is identified as the mostly used agricultural system in miombo areas of Tanzania if enough land is available.

The article studies the ecology of shingle beach plants. The author mentions some of the relevant papers on shingle beaches as a plant habitat, or on their vegetation. Each of the two principal factors, beach composition and shingle mobility, is continuously variable in itself as well as interacting with other factors such as local topography, climate and water supply, and the whole is influenced by time and by past history, according to the author. The author says that the material of shingle beaches consists of two components, the shingle or coarse fraction and the matrix or fine fraction.

The article describes a cold-temperature region farther north on the same coast. The field work on which it is based was done between June 28, 1948 and September 1948. A general ecological account of the intertidal plant and animal populations of the Nova Scotia region is provided. A stretch of rocky coast adjacent to the harbor in Nova Scotia is described. It emphasizes the difficulties in distinguishing well-marked zones above the infralittoral fringe. The zonation between tide-marks shows very marked variations in the region.

The article lists several papers on ecology of bryophytes including "Note on the biology of Fegatella conica," by Annie C. Maybrook, "Xerophytic adaptations of bryophytes in relation to habitat," by W. Watson and "A note on the reversibility of the water relation in a desert liverwort," by W. A. Cannon.

The article reports on the acquisition of the journal "The Plant World" by the Ecological Society of America in the U.S. It says that the acquired journal bears the title "Ecology". The acquisition made the journal as the organ of the Society and will publish papers both on plant and animal ecology. Furthermore, the Plant World journal has always published several ecological papers, and its successor, the Ecology journal may now be expected to become one of the main outlets for American ecological work.

The representation of physical and complex biological systems in terms of organismic supercategories was introduced in 1968 by Baianu and Marinescu in the attached paper which was published in the Bulletin of Mathematical Biophysics, edited by Nicolas Rashevsky. The different approaches to relational biology, developed by Rashevsky, Rosen and by Baianu et al.(1968,1969,1973,1974,1987,2004)were later discussed. The present paper is an attempt to outline an abstract unitary theory of systems. In the introduction some of the previous abstract representations of systems are discussed. Also a possible connection of abstract representations of systems with a general theory of measure is proposed. Then follow some necessary definitions and authors' proposals for an axiomatic theory of systems. Finally some concrete examples are analyzed in the light of the proposed theory. An abstract representation of biological systems from the standpoint of the theory of supercategories is presented. The relevance of such representations forG-relational biologies is suggested. In section A the basic concepts of our representation, that is class, system, supercategory and measure are introduced. Section B is concerned with the mathematical representation starting with some axioms and principles which are natural extensions of the current abstract representations in biology. Likewise, some extensions of the principle of adequate design are introduced in section C. Two theorems which present the connection between categories and supercategories are proved. Two other theorems concerning the dynamical behavior of biological and biophysical systems are derived on the basis of the previous considerations. Section D is devoted to a general study of oscillatory behavior in enzymic systems, some general quantitative relations being derived from our representation. Finally, the relevance of these results for a quantum theoretic approach to biology is discussed. http://www.springerlink.com/content/141l35843506596h/

Samples of dace were taken from the Afon Llynfi and the River Lugg each month for 13 consecutive months. Male dace grew faster than females and rates were comparable with those described for several other populations. Variations in year-class strengths were observed and these differed between the populations although 1959 was strongly represented in both. The sex ratio varied throughout life and disturbances in the expected ratio were attributed to the attainment of sexual maturity at the end of the fourth year of life (3+). Observation of the seasonal gonad cycles indicated that spawning occurred in March or April. Fecundity was estimated at about forty eggs per gram of total weight. A seasonal cycle of feeding activity was established with highest food consumption during summer. There was evidence of a fast during the spawning period. No correlation between temperature and feeding activity could be established. Dace were omnivorous, but aquatic insects and algae were the main components of the diet. Seasonal variations generally followed availability. The importance of aerial insects declined with age. Many differences in feeding habits were detected between the populations. [ABSTRACT FROM AUTHOR]

A list of several publications of articles on animal ecology is presented including "The Species of the Genus Aphelenchus," by T. Goodey, "Caithness Mollusca, Pisidium henslowanum (Shepp.)," by C. Oldham, and "A Simple Key to the Crabs (Brachyura) of Britain and the North-East Atlantic," by M. Perkins.

An instrument is described which employs a mercury current-integrator ("Curtis Meter") in series with a thermistor and a mercury battery. This can be used to integrate temperatures at very precisely known localities even in thermally stratified habitats such as soil. The device has an overall accuracy of at least ±0.25°C and can be read in the field without the need of delicate measuring equipment. In the paper a convenient method of calibration is described and some practical results are given to illustrate the effects of vegetation and of aspect as seasonal cycles of soil temperature. [ABSTRACT FROM AUTHOR]

The article concentrates on the effect of war destruction upon the ecology of cities. The author says that to his knowledge little effort has been made to utilize these unique opportunities. The development of an area's ecological structure divorced from its material structure is a phenomenon deserving much attention and thorough study by urban ecologists. In this paper he concentrates on the demographic aspects of war destruction in cities, and primarily on density changes. He says that he is of course, aware that density describes only one aspect of a city's ecology. About other aspects, which are more elusive to a single-handed investigation, he could obtain only some tentative and partial findings. He asserts that density changes are caused by the war. Density is perhaps the most basic feature of a population's spatial distribution as he feels. One aspect of the bombardments of World War II is of greatest importance for density changes, this is the fact that the number of bombed-out people exceeds the number of deaths from air-raids by far.

The article offers information regarding the international symposium on population biology, held at Syracuse University, Syracuse, New York on June 7-9, 1967. The symposium was sponsored by the New York State Science and Technology Foundation and was attended by more than 400 participants. Richard Lewontin of University of Chicago was the chairman of the program.

The article reviews the periodical "The Journal of Ecology.".

A general type of mathematical model based on the matrix representation of first order difference equation is considered in the light of harvesting animal population. Simplifications in the model that occur if harvesting keeps the population level constant are noted and are used to investigate optimum age and sex specific harvesting strategies. A general result is obtained for cropping to be optimal. In the light of these results, the problem of optimal size for the population itself is considered.

Density, height, diameter, and age structure of Pinus taeda L. were examined in a 21-year-old abandoned field. A density estimate of 924 trees ha-1 was obtained, a factor of 17 over that found for the area 14 years earlier. Age frequencies resembled an inverse J-shaped depletion model, with 4.3% of all trees examined being in the 1-year age class. Median ecological longevity was estimated to be 3.2 years. Linear correlations between age, height, and dbh data were also determined. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue including one by J. Davidson on the analyses of the growth rates at different temperatures of various life stages of flies and a moth and another by James Fisher and H. G. Vevers on the monograph on populations of North Atlantic gannet.

The article discusses about Professor and sociologist Fred Cottrell's contributions to political sociology and demography consist largely in his Herculean efforts to trace out the impact on society of the transition from low energy technology to a high energy technology. "Energy and Society," is basically a treatise on the evolution of a new species of society one that is fundamentally different from the species that preceded it in terms of family structure, social structure and organization, spatial organization, values and ideology, population size and diversity, and politics. Departing from the Darwinist model of evolution, Cottrell pointed out that man's ability to transform nonhuman energy to suit his own purposes disrupted whatever natural forces were operating in the environment to keep a balance in the ecology.

Theoretical propositions from human ecology are used to develop a model that explains the centralization or decentralization of various types of families, such as married couples with children, in the Cleveland, Ohio, Metropolitan Area. The model shows how proximity to the Central Business District affects neighborhoods in terms of three characteristics: Age or period of development, both internal and external housing Space, and Site features such as industrial and recreational activity. These structural characteristics are seen, in turn, as the causes of the location of families in relationship to the center of Cleveland. Of the three characteristics, Space generally plays the most important and Site the least important role in determining the location of types of families. However, the location of most types of families is affected by a variety of interrelation- ships among neighborhood characteristics. [ABSTRACT FROM AUTHOR]

Studies in factorial ecology have typically used the principal factor procedure coupled with varimax rotation. Since it can be shown that the results one obtains vary according to the factor and rotation models he employs, and since there is no one "best" way of obtaining initial and derived factor solutions, it is proposed that future research in the area adopt an approach involving the simultaneous use of several different computing algorithms for obtaining initial solutions and both orthogonal and oblique rotation procedures to avoid the possibility that the results one obtains are not method-dependent. Ideally, the factor models employed should differ maximally with respect to the principles upon which they are based. If one finds a given factor regardless of the method he uses, only then can he assert with any confidence that it is not an artifact of his method. Factorial ecologists are often interested in computing "factor scores", but "true" factor scores are not uniquely computable; they can only be estimated. Since the proposed research strategy involves using either a component or an image model, in which the corresponding scores are exact and uniquely computable, the factor score problem is, in a sense, solved. Next it is suggested that, by using orthogonal solutions, factorial ecologists may be overlooking a very important piece of information-the correlation between the factors. There is some reason to believe that this varies from city to city, and may account for the fact that some factors which emerge in studies of Western cities are sometimes not found in cities elsewhere. Some comments are also made on the value of using census tract data, and on the availability of computer programs for different initial and derived factor solutions. [ABSTRACT FROM AUTHOR]

Discusses a survey conducted on the effects of biotic factors on populations of the desert locust. Studies related to the mortality of the desert locust and its effect on population; Observations made in locust mortality in post embryonic stages; Role played by insect parasites in extinction of desert locust population; Lack of information related to the natural mortality of desert locust.

The author reflects on the possible schism between the advancement in technology and the developments in the ecology. According to the author, technology and ecology may be compatible in the developments in their separate fields and working together. The author suggests in order for the two fields to prosper, they must work together as partners, liberated from the constraints which their past history has imposed on them.

The article presents a study on the ecological dynamics of watersheds. The article begins with an introduction on the substantial literature on watersheds, which began in the seventeenth century to the present, with studies varying from the simplest concepts to complex ideas or models of watersheds. The study formulates a mathematical model on the ecological dynamics of watersheds. It also defines and explicates key concepts useful in the study such as ecosystem, watershed, energy flow, modeling and water dynamics. The study concludes that the graphic transfer function model has been developed to show in a simple and comprehensive form the pathways for water, energy and elements within a watershed.

The article presents a study on the relationships between ecosystem structure and function during autotrophic succession of a laboratory microecosystem. Various microorganisms were obtained from a farm pond. They were added to one liter of medium and were allowed to reorganize and grow for several months. The replicate ecosystems were covered with a glass plate and incubated with a Sylvania standard Gro-lux light source. Net community photosynthesis was determined by observing the pH change of the replicate microecosystems between the time the lights go on and lights go off.

The article discusses adaptations in the ecosystem. It states that in the investigation of ecosystems, the controversy has centered upon the relations between the biotic components. Scientists have pointed out that environments vary both in space and in time and the vegetation will not be the same in any two places. Most demonstrations of vegetational continua are stated to have been made from the sampling of stands within a single plant formation. The reason stated for this is to be expected because when two communities differ in physiognomy, there is a change in species composition on passing from one to the other.

The article focuses on the role of environment in the growth and processes of living organisms. It informs that the energy supplied by environment is used by DNA that mobilizes various processes in living organisms. It explains that the primary aim of ecologists involves the study of relationship between the ecosystem, the organisms and population and mentions that ecology focuses on analyzing the physical and chemical aspects of environment. Also described are the aims related to the study of environment, which include investigations related to the relationship between organisms and environment and physiological aspects of extreme environments.

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The article presents a revised method for grouping sites on the basis of their vegetation. Using frequency modulated relative homogeneity function, the similarities among the sites are calculated and are shown as glyphs on a map because the maps allow a generally precise interpretation of the relations in continua and at community boundaries. The homogeneity function is also used to calculate the centroid and the similarity between community and each site. An illustrative example of using the method is provided. It is concluded that the method can be used where there are large changes in overall abundance from thinly to densely vegetated areas. The study also suggests a way for extending the method to the problem of finding the associated environmental conditions for communities.

The article presents a study on thinning in plant populations. It mentions that plants in natural environments survive through phenotypic plasticity and are prone to dying before reproduction. It discusses studies on the density-related mortality and the finding that the survival of plants is related to their weight. The study involves the growing of radish and rape cultivars in pure populations and in soils of varying fertility. Harvests were taken at different periods in seventeen weeks. An overview of the results is provided.

The article highlights a study of the ecology of Hordeum murinum L. in Great Britain. It notes that a punched card technique is described for the analysis of distribution maps. It mentions that the technique allows analysis of complex patterns, the data are amenable to statistical analysis and use is made of negative information. It reports that the distribution of Hordeum murinum and Reseda luteola is shown to be correlated with climate and with the distribution of urban land. It also discusses some of the problems of analysis of distribution patterns using visual comparison and the punched card technique.

Information about the Autumn Meeting of the Tropical Group of the British Ecological Society, that was held in the Department of Botany, University College London, on October 30, 1967 is presented. Topic includes the virus ecology in the Amazon forest, the ecology of the rodent reservoir of Leishmania in British Honduras, and the aspects of mosquito ecology in South-East Asia. Several notable researchers were featured in the meeting including L. J. Webb, J. P. Woodwall, and R. H. L. Disney.

The article presents the study regarding the nature and composition of desmid plankton. The main problem of the study is the recognition of euplanktonic as opposed to tychoplanktonic desmids and the distinctiveness and antiquity of the euplanktonic community. The solution is to use phytoplankton quotients for the determination of lake trophicity, where the number of planktonic desmid species may form the denominator. Moreover, the division between euplanktonic and facultatively planktonic desmids is said to be unreal, though a real distinction may be made between the groups together with the non-planktonic desmids.

The article presents a study that investigates the ecological condition of tidal submergence and chlorinity in Spartina salt marshes in Poole Harbour, England. In the study, samples were collected from three different areas within Poole Harbour where fresh water and sea water meet and mix and manifest evidences of swarding and surface scour erosion as well as by observing its tidal submergence level. The study reveals that tidal submergence factor is essential in suppressing Spartina growth with a maximum height of six inches during active period and can withstand nine hours of tidal submergence with high chlorine tolerance.

The article presents a physiognomic vegetation map of Australia. The author mentions several incomplete vegetation maps of the continent. The author contends that a useful vegetation map is one that is capable of widespread use and one based on a classification that enables specialists, outside plant taxonomy and ecology, to recognize vegetation characteristics and environmental relationships and to be able to make comparisons. It states that the recent comprehensive analyses of the methodology of plant geography demonstrates the increasing awareness of the significance of structure in vegetation classification.

The article investigates the spatial patterns of two plant species in a community. It also attempts to study the relationship between the two species that grow in the same area and identify whether the joint occurrences of both species in the same quadrats is greater or less than chance expectation. The researcher has studied the nearest-neighbor relationships of the members of the population to determine and measure the segregation of the two species. It is noted that a two-species population may be considered symmetrical or unsymmetrical regardless of its degree of segregation. To unveil the concepts established, the researcher has applied the field results from a mixed stand of Douglas fir and panderosa pine.

The article presents an analysis of the population changes in Acidiphilous Grass-heath in Breckland, Great Britain,during 1936 to 1957. According to the author, the Acidiphilious Grass-heath are grasslands in Breckland wherein certain species of rabbits are invading. A quantitative data reports that the decrease in plant populations in the Acidiphilous Grass-heath grasslands show the systematic problem basing a valid diagnosis of a plant community on the results obtained. The author further explained that structured community with a dominant, and a community without the dominant, where the species appear to react interdependently to each other, represent bases for extreme views on the nature of the plant community.

The article presents a study on the ecology of a South African fen, Groenvlei. It relates that Groenvlei is a shallow coastal lake between Wilderness and Goukamma River on the south coast of South Africa where rainfall is evenly distributed and it is also described as calcareous due to the presence of sand dunes as well as eutrophic by nature. The study describes the trends in plant succession which include the primary succession leading to fen carr as well as the secondary succession due to human utilization of the fen. The study also identifies a slight tendency to isotropic conditions and the vegetation of sand intrusions, sandy fen margin and dunes surrounding the lake.

The article presents a study which examines the fragments of natural Shetland scrub and its pattern in Scotland. The relationship of the scrub to the Shetland climate and the probable vegetation zones in Scotland generally is also discussed. The effect of land treatment on the distribution of species and communities is examined. According to the study, Shetland and South Uist scrub is Sub-Alpine and from evidence of planted trees, that it may be replacing defunct submontane Betula woodland over the lower and of its range.

The article presents a study which examines the distribution of some common plants and animals of the littoral and shallow sublittoral regions in relation to wave action in the Lough Ine area. Thirty-three accurately defined stations have been used for the study of the distribution and population density of common plants and animals of the littoral and sublittoral regions in the Lough Ine area. According to the study, littoral species treat the Rapids as sheltered, probably because there is little splash.

The article offers information on the multivariate methods in plant ecology. Association-analysis in plant communities was conducted using the method developed by D. W. Goodall in 1953. Goodall developed the utility of interspecific associations for sorting quadrants into groups is based on definition of a homogeneous unit of vegetation as one in which all species-associations are indeterminate or non-significant. Details related to the ecological information obtained from two heathland communities are presented, followed by discussion on the conclusion that a method by Goodall is likely to prove a very useful tool in primary survey.

The article looks into the ecology of coastal lands of the Red Sea. The Red Sea coastal belt stretches at about 20 kilometers (12 miles) wide and 125 kilometers (80 miles long. This belt includes a littoral coral beach of about one mile in width and a maritime plain, and has three main ecosystems namely salt marsh, desert plain and hills. The study focuses on the first two ecosystems. The study also looked into the annual rainfall and the geology and morphology of the three zones parallel to the coastline. A description of a number of communities ranging from the mangrove vegetation to the dried saltmarsh adjacent to the desert plain is also presented.

The article discusses the effect of quadrat size on the estimation of the Neyman type A series and Thomas series parameters. Both the Neyman and Thomas distributions are preferred in theoretical contagious distributions commonly applied to plant and insect populations. Both series are based on two assumptions that assume that plants occur in randomly distributed centers and that the number of seedlings or vegetative shoots per cluster is also random. Several conclusions were drawn from assumptions on plant distribution according to the models based from both the Neyman and Thomas series and on clusters appearing not very small and not visibly distinct. One of the conclusions include the size chosen for the quadrats substantially affects the result.

The article describes the plant and animal ecology of the Upper Moorland and Alpine Desert zones. It offers various observation about the subject which was given by the author. According to the report, the Shira Plateau, located in the Upper Moorland zone, on Kilimanjaro has an area of about 24 square miles between 11,800 and 13,800 feet of altitude. It discussed the vegetation of a route up the western side of the mountain, between 5,500 and 12,000 feet; and also the change of vegetation above the Shira Plateau between 13,800 and 16,000 feet.

The article offers an interpretation of the discontinuous distribution shown by some British plant species of open habitats. It attempts to clarify the problem of interpreting the discontinuous distribution in Great Britain of flowering plants. It also mentions that the British flora contains many varieties of species occurring in few localities which are widely segregated from each other and from the nearest extra-British stations. It also mentions that two factors in the environment are almost always to be located in floristically rich localities, the presence of basic rock or base-rich drainage water, and the absence of the natural dominant woodland.

The article reports on the ecology of the halophytic vegetation in Lake Ellesmere, New Zealand. In perspective of the great significance of the duration and frequency of flooding in controlling the zonation of halophytic vegetation, the altering conditions of inundation must have had a marked effect on the vegetation. Moreover, with the periodic growth in lake level due to the inflowing of fresh water from the Selwyn and other rivers, the salinity of the lake waters changes substantially. It was discovered to be from one-half to one-sixth as saline as sea water although mostly nearer the lower value.