scholarly journals Statistical analysis of the phytocoenose homogeneity. IV. Species number and mean biomass value as functions of the area size

2014 ◽  
Vol 54 (4) ◽  
pp. 493-509 ◽  
Author(s):  
Anna J. Kwiatkowska ◽  
Ewa Symonidis
Keyword(s):  
Statistical Analysis ◽  
Species Number ◽  
Individual Species ◽  
Logarithmic Function ◽  
Standing Biomass ◽  
Representative Area

Homogeneity of the <em>Leocobryo-Pineturn</em> phytocoenose was assessed on the grounds of the effect of area size on the species number and mean biomass value. It was confirmed that: I) species number was a logarithmic function of the area size; 2) relation of individual species biomass to the area size was, as a rule, other than rectilinear, 3) the size of phytocoenose floristicly representative area differed from that determined with respect to the standing biomass and 4) phytocoenose homogeneity is related to the scale defined by the size of representative area.

scholarly journals Statistical analysis of the phytocoenose homogeneity. II. Species frequency distribution and frequency distribution of the standing biomass as a function of the area size

2014 ◽  
Vol 54 (4) ◽  
pp. 465-475
Author(s):  
Anna J. Kwiatkowska ◽  
Ewa Symonides
Keyword(s):  
Statistical Analysis ◽  
Frequency Distribution ◽  
Spatial Differentiation ◽  
Ground Layer ◽  
Statistical Characteristics ◽  
Individual Species ◽  
Frequency Distributions ◽  
Species Frequency ◽  
Standing Biomass

Homogeneity of the <em>Leucobryo-Pineium</em> phytocoenose was assessed on the grounds of the species frequency distribution and frequency distributions of the total ground-layer biomass and those of individual species. It was confirmed that: 1) species frequency distribution and frequency distribution of biomass, as well as their statistical characteristics depended on the area size and 2) for analysed phytocoenose the area at which frequency distributions of both measures were symmetrical could be determined. The studies showed that phytocoenose homogeneity was related only to the definite area size, i.e. to the definite scale of its spatial differentiation.

Stability and Variability in Competitive Communities

Science ◽  
1999 ◽  
Vol 286 (5439) ◽  
pp. 542-544 ◽  
Author(s):  
A. R. Ives ◽  
K. Gross ◽  
J. L. Klug
Keyword(s):  
Species Level ◽  
Community Level ◽  
Competitive Interactions ◽  
Species Number ◽  
Individual Species ◽  
Community Stability ◽  
Environmental Fluctuations ◽  
The Individual ◽  
Theoretical Analyses

Long-term variability in the abundance of populations depends on the sensitivity of species to environmental fluctuations and the amplification of environmental fluctuations by interactions among species. Although competitive interactions and species number may have diverse effects on variability measured at the individual species level, a combination of theoretical analyses shows that these factors have no effect on variability measured at the community level. Therefore, biodiversity may increase community stability by promoting diversity among species in their responses to environmental fluctuations, but increasing the number and strength of competitive interactions has little effect.

scholarly journals Species diversity of segetal communities in tuber crops and in winter and spring cereals

2013 ◽  
Vol 66 (3) ◽  
pp. 95-102
Author(s):  
Zofia Rzymowska ◽  
Maria Ługowska ◽  
Janina Skrzyczyńska
Keyword(s):  
Species Diversity ◽  
Species Abundance ◽  
Wiener Index ◽  
Species Number ◽  
Individual Species ◽  
Soil Conditions ◽  
Weed Communities ◽  
Spring Cereals ◽  
Dominance Indices ◽  
Tuber Crops

The work presents the results of studies on the diversity of weed communities in tuber crops as well as in winter and spring cereals under similar climatic and soil conditions. We examined overall species abundance in the groups analysed, the average species number per relevé, as well as weed cover of the study area. Additionally, species composition, number of individual species and their biomass were determined. Dominant species in each crop group were distinguished. Species diversity was determined based on the following ecological indices: the Shannon-Wiener index of biodiversity <em>H’</em> and Simpson’s index of dominance <em>C</em>. The indices were computed on the biomass and number-of-species basis. The objective of the work was to compare the structure and diversity of weed communities in the crops studied. The communities analysed differed in all the characteristics examined. Differences were found between biodiversity and dominance indices calculated for individual crop groups, but their significance depended on the method applied to calculate the indices.

Grazing management studies within the Temperate Pasture Sustainability Key Program: experimental design and statistical analysis

2000 ◽  
Vol 40 (2) ◽  
pp. 143 ◽  
Author(s):  
B. A. Orchard ◽  
B. R. Cullis ◽  
N. E. Coombes ◽  
J. M. Virgona ◽  
T. Klein
Keyword(s):  
Statistical Analysis ◽  
Experimental Design ◽  
Management Strategy ◽  
Management Strategies ◽  
Random Coefficients ◽  
Individual Species ◽  
Data Set ◽  
Planning And Design ◽  
Species Groups

Long-term agricultural experiments such as the Temperate Pastures Sustainability Key Program (TPSKP) present significant challenges in the areas of planning and design, conduct, analysis and reporting. This paper concentrates on 2 aspects, namely, the experimental design and the statistical analysis. For long-term agricultural experiments which examine the effects of management strategies over time, an enumeration of the initial biodiversity is essential and permits the allocation of treatments to plots in such a way that potential bias in the estimation of treatment effects due to lack of uniformity in experimental units (plots) is reduced in the covariate analysis. Spatial replication is considered essential and the design should include at least 2 starting dates for management strategies so that the possible interaction between the year of start and the management strategy can be described. The data resulting from repeated measurement of herbage mass of major individual species or species groups represent a longitudinal data set with complexity due to the staggered commencement of treatments and also in part due to the nature of some of the strategies (closure and cuts). The analysis presented is the cubic smoothing spline approach of Verbyla et al. (1999) which integrates cubic splines, random coefficients, covariance modelling and estimation of systematic deviation. This approach, based on linear mixed models and using residual maximum likelihood (REML) has the flexibility to cope with the staggered imposition of management strategies and permits the partitioning of trends into smooth and non-smooth components, thereby quantifying species persistence and seasonal influence under each management strategy.

scholarly journals Statistical analysis of the phytocoenose homogeneity. III. Spatial distributions of species and their standing biomass as a function of the area size

2014 ◽  
Vol 54 (4) ◽  
pp. 477-491 ◽  
Author(s):  
Anna J. Kwiatkowska ◽  
Ewa Symonides
Keyword(s):  
Spatial Distribution ◽  
Statistical Analysis ◽  
Spatial Differentiation ◽  
Spatial Distributions ◽  
Species Dispersal ◽  
Qualitative And Quantitative ◽  
Standing Biomass ◽  
Non Parametric

Homogeneity of the <em>Lcucobryo-Pineium</em> phytocoenose was assessed on the grounds of species dispersal and spatial distribution of their biomass, determined with non-parametric runs test. It was confirmed that: 1) species dispersal and the type of spatial distribution of their biomass depended on the area size, 2) for analysed phytocoenose the area at which species dispersal and spatial sequence of the high and low standing biomass were random could be determined, 3) phytocoenose was homogeneous only under the difinite scale of its spatial differentiation, and 4) scale under which phytocoenose was homogenenous differed for qualitative and quantitative measures.

Statistical analysis of classification

1966 ◽  
Vol 24 ◽  
pp. 188-189
Author(s):  
T. J. Deeming
Keyword(s):  
Multivariate Analysis ◽  
Statistical Analysis ◽  
Classification Scheme ◽  
Analytical Procedure ◽  
Narrow Band ◽  
Scientific Research ◽  
Maximum Amount ◽  
Amount Of Information

If we make a set of measurements, such as narrow-band or multicolour photo-electric measurements, which are designed to improve a scheme of classification, and in particular if they are designed to extend the number of dimensions of classification, i.e. the number of classification parameters, then some important problems of analytical procedure arise. First, it is important not to reproduce the errors of the classification scheme which we are trying to improve. Second, when trying to extend the number of dimensions of classification we have little or nothing with which to test the validity of the new parameters.Problems similar to these have occurred in other areas of scientific research (notably psychology and education) and the branch of Statistics called Multivariate Analysis has been developed to deal with them. The techniques of this subject are largely unknown to astronomers, but, if carefully applied, they should at the very least ensure that the astronomer gets the maximum amount of information out of his data and does not waste his time looking for information which is not there. More optimistically, these techniques are potentially capable of indicating the number of classification parameters necessary and giving specific formulas for computing them, as well as pinpointing those particular measurements which are most crucial for determining the classification parameters.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1202-1203
Author(s):  
Gianluigi Botton ◽  
Gilles L'espérance
Keyword(s):  
Statistical Analysis ◽  
Spatial Resolution ◽  
Personal Computer ◽  
Systematic Study ◽  
Present Author ◽  
Chemical Elements ◽  
Detection Limits ◽  
Research Groups ◽  
Quantitative Performance ◽  
Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

Modelling ecosystem adaptation and dangerous rates of global warming

2019 ◽  
Vol 3 (2) ◽  
pp. 221-231 ◽  
Author(s):  
Rebecca Millington ◽  
Peter M. Cox ◽  
Jonathan R. Moore ◽  
Gabriel Yvon-Durocher
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Diffusion Rate ◽  
Individual Species ◽  
Genetic Evolution ◽  
Rates Of Change ◽  
Rapid Climate Change ◽  
Warming Climate ◽  
Intraspecies Competition ◽  
High Trait

Abstract We are in a period of relatively rapid climate change. This poses challenges for individual species and threatens the ecosystem services that humanity relies upon. Temperature is a key stressor. In a warming climate, individual organisms may be able to shift their thermal optima through phenotypic plasticity. However, such plasticity is unlikely to be sufficient over the coming centuries. Resilience to warming will also depend on how fast the distribution of traits that define a species can adapt through other methods, in particular through redistribution of the abundance of variants within the population and through genetic evolution. In this paper, we use a simple theoretical ‘trait diffusion’ model to explore how the resilience of a given species to climate change depends on the initial trait diversity (biodiversity), the trait diffusion rate (mutation rate), and the lifetime of the organism. We estimate theoretical dangerous rates of continuous global warming that would exceed the ability of a species to adapt through trait diffusion, and therefore lead to a collapse in the overall productivity of the species. As the rate of adaptation through intraspecies competition and genetic evolution decreases with species lifetime, we find critical rates of change that also depend fundamentally on lifetime. Dangerous rates of warming vary from 1°C per lifetime (at low trait diffusion rate) to 8°C per lifetime (at high trait diffusion rate). We conclude that rapid climate change is liable to favour short-lived organisms (e.g. microbes) rather than longer-lived organisms (e.g. trees).

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