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Gewählte Publikation:

Schlick-Steiner B.C., Steiner F.M. & Moder K..
(2003): Ant nests in linear habitats: A new technique for estimating the density of sedentary organisms. Simulation and case study
Sociobiology, 42, 163-174

1. Quantification of organisms is a crucial point in ecological studies Density, frequency and frequency score are different measures of relative quantification. Calculating the frequency score with nested quadrat plots ("quadrat method") was designed for vegetation ecology and has so far not been applied to animal populations. 2. The ecologically important ants have to date been quantified by determining the absolute number of nests of a certain area, the frequency of nests, the relative abundance of individuals based on pitfall trap catches and on baits and by direct counting of foraging individuals. 3. Linear habitats cover a substantial surface area in today's world and are of increasing importance in ecological studies. 4. For the quantification of sessile organisms, such as ant colonies, in linear habitats, a new method of rectangular plots and subplots ("strip method") is based on the same principles as the established quadrat method and is proposed for frequency scores. 5. The quadrat method, the strip method and counting of absolute numbers of individuals in the plots were compared in a computer simulation and a case study on ant nests. Both community structure issues and population issues were taken into account. 6. The strip and the quadrat method are highly similar with respect to the number and identity of species quantified, even for the small number of replicates in the case study. 7. Compared with nest densities obtained by nest counts, the frequency scores of the quadrat and the strip method reflect the community structure in a similar way, with minor shifts in rank order. 8. Frequency scores from the quadrat and the strip method are identical in the simulation and highly similar in the case study, with one exception, where the strip method performs better. This reflects the clustering of nests. An advantage of the strip versus quadrat method seems to be higher robustness against differences in distribution types at low numbers of replicates. 9. Diversity and evenness based on frequency scores of the quadrat and the strip method are consistently higher than the corresponding values based on nest counts. This is due to a general overestimation of species with low nest densities by both frequency score methods, making the community structure appear more uniform. 10. Overall the new strip method can readily be used to quantify sedentary organisms, is especially well suited for studying linear habitats and could also be used for the study of fine-scale ecotones.
Autor*innen der BOKU Wien:
Moder Karl
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Find related publications in this database (Keywords)
community structure
fine-scale ecotone
frequency score
linear habitats
nest counts
nested plots
sampling bias
sessile organisms
strip method

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