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  • 1
    Publication Date: 1986-03-01
    Print ISSN: 0020-7128
    Electronic ISSN: 1432-1254
    Topics: Geography , Physics
    Published by Springer
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  • 2
    Publication Date: 1968-12-01
    Print ISSN: 0043-1656
    Electronic ISSN: 1477-8696
    Topics: Geosciences
    Published by Wiley
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  • 3
    Publication Date: 1959-10-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 4
    Publication Date: 1968-03-01
    Print ISSN: 0016-7398
    Electronic ISSN: 1475-4959
    Topics: Geography
    Published by Wiley
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 184 (1959), S. 1425-1426 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A search of published information and local records regarding two outbreak regions of the red locust, the Mweru wa Ntipa in Northern Rhodesia and the Rukwa Valley in Tanganyika, suggested that wet periods of years were always unfavourable to locust numbers and dry periods were sometimes ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 6 (1963), S. 123-132 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les populations adultes du criquet nomade dans certains foyers d'origine ont été estimées pendant un certain nombre d'années. La technique employée consiste à conduire un véhicule suivant un tracé préétabli de façon à couvrir systématiquement la superficie et de compter le nombre de sauterelles chassées d'une bande de la largeur d'un Land Rover; les nombres sont notés tous les 160 mètres. Le coëfficient de dispersion (la variance divisée par la moyenne) a été calculé par le comptage des criquets s'envolant dans les sections de 160 m. Celui-ci est un index de la proportion relative de criquets à des densités hautes et basses. Il est indépendant de la grandeur totale de la population de sorte qu'il est possible de faire des comparaisons tant entre les distributions de la population dans des régions différentes et les distributions existant à des périodes différentes dans la même région. La comparaison de ces indices démontra qu'en général le coëfficient de dispersion était le plus élevé vers le milieu du stade adulte (juin, juillet, aôut) c.à.d. qu'à ce moment la plus grande proportion de la population était concentrée sur la plus petite surface. A cause du nombre d'exemples relativement petit il est difficile de déterminer l'effet indépendant d'autres facteurs sur le coëfficient de dispersion. Il est cependant probable qu'à une densité moyenne de criquets plus élevée la proportion de criquets était plus grande à des densités élevées. En outre la densité des criquets formant des essaims est en effet très élevée; la formation d'essaims tendait à accroître le coëfficient de dispersion. Un traitement insecticide paraissait réduire le coëfficient de dispersion. Ceci n'est pas surprenant puisque seuls les essaims en repos on été attaqués. Enfin il est possible que la proportion de criquets à des densités élevées était plus grande dans un habitat relativement uniforme que dans un habitat consistant en des morceaux de terre avec des herbes longues et courtes ou en des terres incinérées et des plages non incinérées.
    Notes: Abstract The coefficient of dispersion, an index of the relative proportion of the population at high and low densities, was calculated for a number of outbreak area populations of the red locust. The comparison of these indices showed that the proportion of the population at high densities was greatest near the middle of the adult locust's life. The data suggested that the proportion of locusts at high densities was greater with higher mean locust densities and after the formation of swarms. On the other hand this value was probably lower in a habitat made up of patches of tall and short grass or of burnt-off ground and unburnt stands, than in uniform grassland, and was probably also lower after insecticide attack than before.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of biometeorology 30 (1986), S. 53-64 
    ISSN: 1432-1254
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract In interior eastern Australia, adults of the Australian plague locust with substantial fat reserves migrate down-wind on warm nights if there has been a strong surface wind during the day; limited dispersion occurs with all adult infestations and requires only that the sunset temperature be above the flight threshold. The frequencies of the 900 mb wind, which is near the locust's flying height, from different directions on nights suitable for either mass migration or limited dispersion, have been found for representative months. These differ from the frequencies for all nights in the southern parts of the area, especially in the spring and autumn, since winds are generally warmest from the north. Northerly and westerly locust displacements should occur frequehtly except in the extreme south. Such movements have been observed only rarely. Nevertheless upsurges in the remote interior, where most major plagues start, may be followed by abortive migrations to the desert areas further west as often as by invasions of the farming belt to the south and east.
    Type of Medium: Electronic Resource
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