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Résumé :
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Different methods, such as extraction cylinders, coloured traps, are used to sample saproxylic beetles. Window-flight trapping is the most frequently used technique for catching flying active saproxylic beetles. Window-flight trap devices may differ by the following parameters: plate area, plate shape (plane or crossed), plate colour (transparent or black), bait. Several compiled ecological data sets were analysed with a methodological point of view to compare sampling methods. In the goal of harmonizing sampling methods among studies, this approach aimed at identifying if some sampling methods perform better than others in terms of accuracy, precision and bias to evaluate the cumulative species richness, the species abundance or the assemblage composition. Different analytical methods (power analysis, detectability and exhaustiveness, resampling) were used to compare : -alcoholic-baited or unbaited traps -black- or transparent-window traps -crossed or plane-window traps. Moreover, although biased data are sufficient to address the question of relative differences, it must be assumed that biases are the same between the locations that are being compared. Detectability must not change with habitat structure. That's why we studied the variations in catch efficiency of alcohol-baited or unbaited traps in sun-exposed or shaded conditions. In other words, does trap attractiveness depend on the openness ? The question of the seasonal pattern of sampling across the year was also tackled. First, we assessed the contribution of each sampling season to richness and composition. Secondly we studied the effects of the simplification of a year-catch strategy into a discontinuous trapping design on the representativeness of samples. The available datasets mainly concerned issues at the plot scale and came from forest balanced sampling designs with paired traps on each plot. This saproxylic workshop will give us the opportunity to launch a call for further optimisation analyses based on larger datasets.
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