AERIAL VIDEOGRAMMETRY FROM A TETHERED AIRSHIP TO ASSESS MANATEE LIFE-STAGE STRUCTURE

2000 ◽  
Vol 16 (3) ◽  
pp. 617-630 ◽  
Author(s):  
Richard O. Flamm ◽  
Edward C. G. Owen ◽  
Caryn F. W. Owen ◽  
Randall S. Wells ◽  
Doug Nowacek
Keyword(s):  
Life Stage ◽  
Stage Structure

scholarly journals The dynamics of the population of a steppe perennial Senecio macrophyllus M.BIEB. during xerothermic grassland overgrowing

2011 ◽  
Vol 78 (3) ◽  
pp. 247-256 ◽  
Author(s):  
Bożena Czarnecka
Keyword(s):  
Life Stage ◽  
Stage Structure ◽  
Seed Rain ◽  
Island Population ◽  
Reproduction Mode ◽  
Model Object ◽  
Management Regime ◽  
Brachypodium Pinnatum ◽  
The Individual ◽  
Individual Fecundity

The study aimed to determine the long-term changes of the <em>Senecio macrophyllus</em> M.BIEB. population traits: the abundance, reproduction mode, individual fecundity, seed rain and recruitment of new genets in the course of xerothermic grassland overgrowing. The study had also the applied goal: to estimate the chances of "special care" species to survive in the changing environment without management regime for the maintenance of grassland. The model object was the island population of large-leaved ragwort on Biała Góra (the White Mountain) near Tomaszów Lubelski, South-East Poland. To achieve these aims I used the following sets of data: phytosociological relev,s made in plant communities in an interval of 16-18 years; repeated elaboration of the numbers and life-stage structure of the population, both by non-surface and surface method; observation of plants<sup>,</sup> life cycle in 50 labelled genets; population reproduction and seed rain amounts. The area of an open xerothermic grassland decreased due to the process of overgrowing by bushes which was accompanied by the increasing coverage of forest and meadow herbs as well as monocotyledons, mainly <em>Brachypodium pinnatum</em> and <em>Calamagrostis epigejos</em>. The abundance of the <em>S. macrophyllus</em> population noticable diminished. The flowering mode has been changing during years from an oscillation to a chaotic type which caused the significant decreasing of the individual fecundity, population reproduction and seed rain. In last years it was reflected in the interruption of juveniles’ recruitment.

scholarly journals Stochastic Production Frontier Models to Explore Constraints on Household Travel Expenditures Considering Household Income Classes

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Sofyan M. Saleh ◽  
Sugiarto Sugiarto
Keyword(s):  
Household Income ◽  
Life Stage ◽  
Stage Structure ◽  
Professional Activity ◽  
Stochastic Production Frontier ◽  
Production Frontier ◽  
Household Travel Survey ◽  
Stochastic Production ◽  
Equity Policy ◽  
Household Travel

This paper explores the variation of household travel expenditure frontiers (HTEFs) prior to CC reform in Jakarta. This study incorporates the variation of household income classes into the modeling of HTEFs and investigates the degree to which various determinants influence levels of HTEF. The HTEF is defined as an unseen maximum (capacity) amount of money that a certain income class is willing to dedicate to their travel. A stochastic production frontier is applied to model and explore upper bound household travel expenditure (HTE). Using a comprehensive household travel survey (HTS) in Jakarta in 2004, the observed HTE spending in a month is treated as an exogenous variable. The estimation results obtained using three proposed models, for low, medium and high income classes, show that HTEFs are significantly associated with life stage structure attributes, socio-demographics and life environment factors such as professional activity engagements, which is disclosed to be varied across income classes. Finding further reveals that considerable differences in average of HTEFs across models. This finding calls for the formulation of policies that consider the needs to be addressed for low and medium income groups in order to promote more equity policy thereby leading to more acceptable CC reform.

Demographic methods in epidemiology

2021 ◽  
pp. 351-362
Author(s):  
Petra Klepac ◽  
C. Jessica E. Metcalf
Keyword(s):  
Infectious Disease ◽  
Life Stage ◽  
Stage Structure ◽  
Population Modelling ◽  
Disease Epidemiology ◽  
Infectious Disease Epidemiology ◽  
Structured Population ◽  
The Face ◽  
Demographic Methods ◽  
Host Mortality

Demography is both shaped by and shapes infectious disease dynamics. Infectious pathogens can increase host mortality. Host birth rates introduce new susceptible individuals into the population, which allows infections to persist in the face of the depletion of susceptible individuals that can result from mortality or immunity that can follow infection. Many important processes in infectious disease epidemiology, from transmission to vaccination, vary as a function of age or life stage. Epidemiology thus requires demographic methods. This chapter introduces broad expectations for patterns emerging from the intersection between demography and epidemiology and presents a set of structured population modelling tools that can be used to dissect important processes, including next generation methods, and estimation of R0 in the context of stage structure and with important differences in time-scale between host demography and pathogen life cycle.

scholarly journals Long-Term Changes in Spatial Patterns and Life-Stage Structure in a Population of Senecio umbrosus Waldst. et Kit. Along With the Transformation of Grassland Vegetation

2020 ◽  
Vol 89 (4) ◽  
Author(s):  
Bożenna Czarnecka
Keyword(s):  
Life Stage ◽  
Initial Density ◽  
Floristic Composition ◽  
Stage Structure ◽  
Clustering Coefficient ◽  
Tree Cover ◽  
Island Population ◽  
Litter Cover ◽  
Brachypodium Pinnatum ◽  
Calamagrostis Epigejos

This paper was a part of studies conducted within an island population of the ragwort <em>Senecio umbrosus </em>(White Mt, southeastern Poland), a vulnerable element of xerothermic grasslands. Special attention was paid to the effects of expansive grass encroachment vs. grassland burning episodes on spatiotemporal patterns and life-stage structure of individuals in the population. The population traits were investigated nine times from 1990 to 2010, within three permanent patches differing in soil properties, initial floristic composition, grassland cover (particularly the cover of <em>Brachypodium pinnatum</em>), ragwort cover and density, shrub/tree cover influencing light intensity (full light–shadow), and grassland burning (zero–six episodes). There was a drastic decline in ragwort abundance within all the study patches accompanied by a decrease in the population clustering coefficient and a gradual equalization of the spatial distribution of ramets. The abundance was negatively correlated (PCA analysis) with an increase in <em>B. pinnatum </em>cover and positively correlated with the number of burning episodes, which temporarily delimited persistent litter cover and facilitated recruitment of new individuals. The decrease in ramet abundance ranged from 3.8 times (medium-high, moderately shadowed grassland; six cases of burning) to 8.3 times (high, dense, and shadowed grassland; four cases of burning). The patch of low, loose, sunlit, and never-burned grassland with the greatest initial density of ragwort (a 6.8-fold decrease in abundance) has evolved with time into a high and dense grassland with a greater coverage of <em>B. pinnatum </em>and <em>Calamagrostis epigejos</em>, additionally shaded by shrubs and young trees.

scholarly journals The host status of African buffaloes, Syncerus caffer, for Rhipicephalus (Boophilus) decoloratus

2006 ◽  
Vol 73 (3) ◽  
Author(s):  
I.G. Horak ◽  
H. Golezardy ◽  
A.C. Uys
Keyword(s):  
Life Stage ◽  
Stage Structure ◽  
Syncerus Caffer ◽  
Mpumalanga Province ◽  
Boophilus Decoloratus ◽  
Large Numbers ◽  
Host Status ◽  
Time Of Year ◽  
The One ◽  
Connochaetes Taurinus

The objective of this study was to assess the host status of African buffaloes, Syncerus caffer, for the one-host tick Rhipicephalus (Boophilus) decoloratus. To this end the R. (B.) decoloratus burdens of ten buffaloes examined in three north-eastern KwaZulu-Natal Province (KZN) nature reserves were compared with those of medium-sized to large antelope species in these reserves and in the southern Kruger National Park (KNP), Mpumalanga Province. The R. (B.) decoloratus burdens of the buffaloes were considerably smaller than those of the antelopes in the KNP, but not those in the KZN reserves. The life-stage structure of the R. (B.) decoloratus populations on the buffaloes, in which larvae predominated, was closer to that of this tick on blue wildebeest, Connochaetes taurinus, a tick-resistant animal, than to that on other antelopes. A single buffalo examined in the KNP was not infested with R. (B.) decoloratus, whereas a giraffe, Giraffa camelopardalis, examined at the same locality and time, harboured a small number of ticks. In a nature reserve in Mpumalanga Province adjacent to the KNP, two immobilized buffaloes, from which only adult ticks were collected, were not infested with R. (B.) decoloratus, whereas greater kudus, Tragelaphus strepsiceros, examined during the same time of year in the KNP harboured large numbers of adult ticks of this species. African buffaloes would thus appear to be resistant to infestation with R. (B.) decoloratus, and this resistance is expressed as the prevention of the majority of tick larvae from developing to nymphs.

scholarly journals Population viability in a host-parasitoid system is mediated by interactions between population stage structure and life stage differential susceptibility to toxicants

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
John D. Stark ◽  
Jenifer K. McIntyre ◽  
John E. Banks
Keyword(s):  
Life Stage ◽  
Differential Susceptibility ◽  
Stage Structure ◽  
Diaeretiella Rapae ◽  
Toxicity Data ◽  
Toxicant Exposure ◽  
Cabbage Aphid ◽  
Stage Distribution ◽  
Initial Stage ◽  
Ecological Risk Assessments

AbstractThe effects of toxicants, such as pesticides, may be more severe for some life stages of an organism than others. However, in most toxicity studies, data is developed for only one life stage, which may lead to misleading interpretations. Furthermore, population stage-structure may interact with differential susceptibility, especially when populations consist of higher proportions of individuals in more susceptible stages at the time of toxicant exposure. We explore the interaction of differential stage susceptibility and stage distribution using a stage-structured Lefkovitch matrix model. We incorporate lab-derived toxicity data for a common parasitoid, the braconid Diaeretiella rapae (M’Intosh), a common natural enemy of the cabbage aphid (Brevicoryne brassicae L.), exposed to the pesticide imidacloprid. We compare population outcomes of simulations in which we vary both the population stage structure along with the susceptibility of each stage to toxicants. Our results illustrate an interaction between differential susceptibility and initial stage distribution, highlighting the fact that both of these demographic features should be considered in interpreting toxicity data and the development of ecological risk assessments.

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