Mathematical Model of Seed Dispersal by Frugivorous Birds and Migration Potential of Pinyon and Juniper in Utah

This article discusses the main points of the formation and development of the concept«demographic potential» used for the purposes of management and forecasting in a changing environment. The need for demographic potential as an instrumental, supporting notion arose when researchers began to examine possible effects of demographic processes and their impact on the structure and size of population in the future, i.e. build population projections and population development models. Historically, researchers studied demographic potential separately for each component of the overall population growth. Beginning of the study of fertility potential is associated with the name of R. E. Fisher, life potential — with the work of L. Hersch, migration capacity — with the works of J. Q. Stewart, G. K. Zipf, S. A. Staufer and W. Izard. Attempts to assess the joint effect of different components of the overall population growth were episodic. Only in the 30s of the twentieth century the integrated synthesis indicators began to be used for describing the demographic potential. One of the indicators for capacity of population reproduction may be net reproduction rate. Modern interpretations of the potential of changes in fertility and mortality, migration capacity have a wider purpose and filling than at the time of these concepts’ formation. Demographic potential in a narrow sense is the potential population reproduction, including changes in fertility and mortality; in a broader sense, it is the total potential of population — potential of reproduction and migration potential, including possible changes in the population size and structure due to births, deaths, immigration and emigration.

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The migration component in the demographic development of Russia in the post-war period (1951–2020)

Level of Life of the Population of Regions of Russia ◽

10.19181/lsprr.2021.17.2.7 ◽

2021 ◽

Vol 17 (2) ◽

pp. 235-242

Author(s):

Leonid Rybakovsky ◽

Vladimir Savinkov ◽

Natalia Kozhevnikova

Keyword(s):

First Century ◽

Demographic Development ◽

Demographic Dynamics ◽

Growth Decline ◽

Migration Potential ◽

Natural Movement ◽

Post War ◽

And Migration ◽

The Impact ◽

Migration Component

The article discusses possible combinations of the impact on the dynamics of the population of migration growth (decline) and natural decline (increase). Variants of combinations with the corresponding values of natural and migration movements are shown using examples of the demographic dynamics of Russia. Reliable information about the migration movement of the population refers only to the time that began in the 50s. It is distributed over periods that differ in the nature of the impact of the reproductive and migration components on demographic dynamics. During these periods spanning seventy years, the country's population increased by almost 44 million. In the first 25 years, there was a migration decline, more than offset by natural population growth. Then migration, along with natural movement, acted as a component of population dynamics. Due to natural growth, the population increased to the 1951 level. by 33.8 million people. The migration component accounted for 10.6 million people. Their ratio was 3/4 to 1/4. It is shown that in the second half of the tenth years of the twenty-first century, Russia entered a difficult demographic time for it, aggravated by the fact that by now in the new abroad the migration potential oriented towards Russia has significantly decreased

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Seed dispersal effectiveness by frugivorous birds: Identifying functional equivalent species in bird assemblages

Avian Biology Research ◽

10.1177/1758155919832189 ◽

2019 ◽

Vol 12 (3) ◽

pp. 103-108

Author(s):

Facundo Xavier Palacio

Keyword(s):

Seed Dispersal ◽

Statistical Significance ◽

Bird Species ◽

Kernel Functions ◽

Bird Conservation ◽

Frugivorous Birds ◽

Seed Dispersal Effectiveness ◽

Bird Assemblages ◽

Functional Equivalent ◽

Dispersal Effectiveness

Seed dispersal by birds is a pivotal ecosystem function worldwide; yet, the rapid and ongoing global biodiversity loss poses a major threat to this essential ecosystem service. Seed dispersal effectiveness (SDE) is a key outcome of the interaction, represented by the product of seed dispersal quantity (number of seed dispersed) and quality (probability of recruitment of dispersed seeds). Therefore, identifying functional equivalent species in terms of SDE should become a key issue for bird conservation, since the effects of local extinctions on seed dispersal services may be weakened by remaining equivalent species. However, a method to quantitatively identify functional equivalent species in frugivorous bird assemblages is still lacking. To estimate SDE overlap between seed dispersers and assess whether two species may be functionally equivalent, I apply a novel nonparametric niche overlap index based on kernel functions and null models to test its statistical significance. For each bird species, I account for intraspecific variation in seed dispersal effectiveness to obtain a distribution of seed dispersal effectiveness values, an often neglected source of variation in seed dispersal assemblages. Non-significant differences in seed dispersal effectiveness overlap support the hypothesis that two species are functional equivalent, thus playing similar functional roles. The model proposed is applicable to any other quantity or quality component and is independent from the method or sampling design used to quantify SDE. The identification of functional equivalent species in seed dispersal assemblages adds to the theoretical framework of seed dispersal effectiveness and offers new insights into the ecology of the seed dispersal service provided by birds.

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Constraining fluid migration in low density data area: successful use of integrated modelling in the Southern Perth Basin

The APPEA Journal ◽

10.1071/aj13107 ◽

2014 ◽

Vol 54 (2) ◽

pp. 534

Author(s):

Laurent Langhi ◽

Bozkurt Ciftci ◽

Julian Strand

Keyword(s):

Structural Model ◽

Integrated Modelling ◽

Low Density ◽

Lateral Migration ◽

First Order ◽

Hard Data ◽

Hydraulic Behaviour ◽

Migration Potential ◽

And Migration ◽

Definition Of

Constraining trap integrity or CO2 containment potential in areas with low density of data is challenging. We show here how the integration of hard data and modelling improved our understanding of the subsurface tectonic and stratigraphic architecture and ensured an initial definition of hydraulic behaviour of faults and fractures in the onshore Southern Perth Basin. A first-order geomodel was built based on interpretation of low-density 2D-seismic data and constrained by well, geophysical, and outcrop data. Forward stratigraphic models were deformed and implemented in the geomodel to predict the distribution of the phyllosilicate content. Membrane fault-seal prediction was performed based on the Shale Gouge Ratio algorithm to estimate the lateral migration potential. Characterisation of the stress state of fault planes was used to define the likelihood of reactivation and to predict vertical migration and caprock bypass. The elastic dislocation method was used to model the density and mode of failure of subsidiary sub-seismic faults that can impact on the caprock integrity. This was also used to constrain and validate the structural model. The integrated modelling significantly decreased uncertainties on the subsurface architecture and ensured the first-order definition of the CO2 migration and containment potential for the Wonnerup reservoir in the SW Hub. The maximum CO2 column heights supported by faults and potential leak points were estimated and migration scenarios and risks were defined.

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