O metodyce badania pająków runa lasu sosnowego : Wpływ nierównomierności uderzeń czerpaka na obraz dynamiki liczebności pająków

Łuczak, Jadwiga

doi:ISSN 0424-7205

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Title: O metodyce badania pająków runa lasu sosnowego : Wpływ nierównomierności uderzeń czerpaka na obraz dynamiki liczebności pająków

Abstract:

This report is an attempt at analysing the scoop method in relation to plantloving spiders (living on Vaccinium myrtillus) in a pine forest; the problem examined is whether the unevenness of the strokes made by the scoop affect the results of research work on seasonal quantitative dynamics. This is part of work on the quantitative dynamics of spiders living on the plants of a pine forest, carried out in 1954 and 1955 at Lemański near Częstochowa, now prepared for printing. In field work two types of collection by scoop were used, two series of 10 samplles each (each sample -25 strokes of the scoop) being carried out in each period investigated, at each station, on the same day and at the same time of day. One of these was carried out by quick sweeps, the other by purposely slower sweeps. The quantitative and qualitative spider material obtained in this way from these double comparable series (75 species, 4321 individuals from “quick sweeps” and 1930 from “slow sweeps”) enable the following conclusions to be reached:l. The dominating species are shown correctly regardless of lthe speed of sweep. The spider material collected may exhibit dillerences depending on speed of sweep in the order of dominating species according to their numbers. The percentage of domination is not always the same in both types of sweep, but always demonstrates the actual quantitative domination of the species, defined by means of a different method as dominant or influent (Table I).2. ,,Slow sweeps” often collect smaller quantities of species from the environment examined than “quick sweeps” (Table II]). Both types of sweep show 65% of species common to both (Table III).3. Quicker strokes of the scoop are more effective in colecting spiders on account of the defensive reaction of the latter. In the life cycle of spiders variations occur in their reactions to danger. This phenomenon was examined by means of an “indicator of defensive reaction” of the species, this indicator being obtained by dividing the number of individuals caught by the “quick scoop” by the number of individuals caught by the “slow scoop” (Tables IV, V, VI).4. Collection capacity of the scoop varies not only according to the defensive reaction of the species of spider, but also to the type of web and the place in it occupied by the spider.5. While taking into account the above drawbacks, which make it essential that great care is taken in drawing conclusions from material collected by the scoop method, it is however possible to draw several correct conclusions from this method as to the seasonal quantitative dynamics of spiders living in the surface layer of the plants of the forest, as follows: conclusions regarding the general variability of quantitative dynamics of all spiders, quantitative variations of their ecologica1 groups in a wide sense, and quantitative dynamics of the most numerous species of the environment examined (fig. l, 2, 3).

References:

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2. Gałecka, B. 1953 - Uzupełnienie do projektu instrukcji połowu czerpakiem. - Biul. Kom. Ekol.
3. Skuhravy, V. 1958 - Metody badań nad agrobiocenozami w Czechosłowacji. - Ekol. Pol. B, 4.
4. Skuhravy, V. i Novak, K. 1957 - Entomofauna bramboristi i jeji sezonni vyvoj - Rozpr. Ceskosl. Akad. Ved. 67.
5. Tarwid, K. 1953 - Instrukcja ilościowego połowu czerpakiem. (projekt) - Biul. Kom. Ekol.