Agelenids of the World

Systematics and Taxonomy of Agelenidae, a Worldwide distributed Spider Family

Methodisches zur Ermittlung der Siedlungsdichte von Bodentieren aus Quadratproben und Barberfallen

Publication Type:Journal Article
Year of Publication:1988
Authors:U. Franke, Friebe, B., Beck, L.
Date Published:1988
ISBN Number:0031-4056
Keywords:Ecological techniques, Ecology, Ettlingen]., Eurasia, Europe, evaluations] [Soil habitat / / technique evaluations] [Germany / /, Habitat, Invertebrata (Animalia)., Invertebrata [Population density measurement / / Pitfall trap & quadrat, Land zones, method evaluations] [Population density / / Estimation technique, Palaearctic region, Population dynamics, Techniques, Terrestrial habitat

During investigations into the soil fauna of beech wood litter mould in Ettlingen municipal Forest near Karlsruhe (Baden-Wurttemberg) the macrofauna was determined by hand sorted quadrats and pitfall traps. Quadrats yield direct population density values. Their precision depends on the efficiency of sorting, their representivity on the sample size. The efficiency was tested by sorting the same sample three times. Efficiency "E" of hand sorting for macro- and mesofauna lies between 63% (Dipteran larvae) and 100% (Gastropoda, Opiliones, Dermaptera); for mesofauna it is inadequate. The represensitivity "R" of a sample was assesed using means and standard deviations of three parallel samples of 1/9 m2. R = 1 - s/.hivin.x, with values between 0.72 (Entomobryidae) and 0.97 (Enchytraeidae), is good to very good for the individual-rich macrofaunal groups. For the poorly represented groups the representivity is bad, with values of 0.56 (Pseudoscorpiones) and 0.48 (Dermaptera), and inadequate for the megafauna, values under 0.22 (Lumbricidae, Gastropoda). On the whole results of hand sorted quadrats multiplied by 1/E are a good estimate of the real abundance of these animal groups. The activity density, detected by pitfall traps, is essentially a product of locomotive activity and population density. To relate activity density to population density pitfall traps were gradually increased from 5 to 9 to 21 to 41 traps per plot to empty a 3 m .times. 3 m area and to determine the range or catch area of a single pitfall trap. The catch area varies for each species, but species can be combined roughly by group and size class. In the two most frequent groups, beetles and spiders, there was no emptying effect for the smaller species. A catch area of ca. 1 m2 could be estimated for the bigger beetles with body length greater than 7 mm - mainly Carabidae - and ca. 0.7 m2 for spiders with body length more than 6 mm - mainly Agelenidae.

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