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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 57 (2002), S. 0 
    ISSN: 1365-2494
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The objective of this work was to determine the applicability of the dry-weight-rank (DWR) method for evaluating the botanical composition of forest understorey vegetation. An analysis of plant species abundance was carried out, and instead of ranking the three most abundant species, as is commonly used, up to twelve ranks were scored. Concurrently, four models of relative abundance distribution (RAD) of species were compared for their ability to explain the abundance of species in the study area. The Power-fraction model resulted in the best goodness-of-fit and it was subsequently used to produce the coefficients for the DWR method. Lin's concordance correlation coefficient, the adjusted coefficient of determination, the residual standard deviation and Spearman's rank-order correlation coefficient indicated a good performance of the DWR method. Biomass data and the Shannon index for diversity were also considered. Further analyses showed that there was a trade-off between the number of ranks scored and the accuracy of the botanical composition produced by the DWR method. It is concluded that, so long as the RAD model that explains the distribution of plant species is known, the DWR method can be applied to forest understorey vegetation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Insectes sociaux 27 (1980), S. 305-311 
    ISSN: 1420-9098
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Resume 1 -Nous avons développé un modèle qui permet de prédire le nombre des œufs, larves, pupes et imagos chez l'abeille domestique (Apis mellifera L.) tout au long de l'année. 2 -Le facteur majeur qui affecte la population est le taux de ponte de la reine. Il est approximativement donné par une courbe de distribution de fréquences de la forme: Yt=atbect 3 -Le nombre d'individus donné par cette équation est alors modifié par des taux de mortalité qui, dépendant de l'âge, sont périodiquement ajustés. 4 -Les informations obtenues à partir du modèle sont comparables aux données réellement obtenues en comptant le nombre d'ouvrières dans les colonies d'abeilles. 5 -Avec des modifications relativement mineures, cette technique de modèles est applicable à d'autres espèces d'insectes monogynes et eusociaux.
    Notizen: Summary 1 -A deterministic model has been developed which can forecast honeybee (Apis mellifera L.) preadult (eggs, larvæ and pupæ) and adult population numbers throughout the year. 2 -The major factor affecting population is rate of lay of the queen which is approximated by a skewed frequency distribution curve of the form: Yt=atbect 3 -Population numbers generated by this equation are then modified by seasonally adjusted age-dependent mortality rates. 4 -Information obtained from the model compares favourably with previously published observational data obtained by counting the numbers of worker honeybees in colonies. 5 -With relatively minor modifications this modelling technique is applicable to other monogynic eusocial insects.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    London : Periodicals Archive Online (PAO)
    The RUSI journal. 16 (1873) 143 
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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