In arable agroecosystems, arthropod communities often have a reduced abundance and diversity, which represents a challenge for sampling techniques needed to detect small differences among these simplified communities. We evaluated the suitability of pitfall traps for comparing the effects of cropping systems on arthropod communities. In a field experiment, we compared the effects of two pitfall trap diameters, the type of preserving fluid and the sampling effort on three metrics (activity density, taxonomic richness, and community weighted mean [CWM] of body size) for carabids and spiders. Trap size affected the observed composition of communities, with large traps yielding a higher proportion of spiders, and a higher richness and CWM body size for both taxa. The type of preserving fluid had a weaker effect. Simulations with various sampling efforts showed that only very different communities could be distinguished with less than 10 traps per field or less than 30 field replicates. Fewer traps were required to find differences between cropping systems for body size than for other metrics. Carabid activity density and body size, and spider genus richness, were the variables better distinguishing between cropping systems with the smallest sampling effort. A high sampling effort was required for comparing activity density and richness across cropping systems. Selection of the most appropriate trap design, metrics, and crops are the main factors for optimizing the trade-off between sampling effort and the ability to detect arthropod community responses to habitat management.

中文翻译：

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选择哪些陷阱和抽样工作来评估种植系统对蜘蛛和 Carabid 组合的影响？

在可耕地农业生态系统中，节肢动物群落的丰度和多样性通常会降低，这对检测这些简化群落之间的微小差异所需的采样技术提出了挑战。我们评估了陷阱陷阱的适用性，以比较种植系统对节肢动物群落的影响。在现场实验中，我们比较了两个陷阱直径、保存液类型和采样工作对carabids 和蜘蛛的三个指标（活动密度、分类丰富度和体型的群落加权平均值 [CWM]）的影响。陷阱大小影响观察到的群落组成，大型陷阱产生更高比例的蜘蛛，两个分类群的丰富度和 CWM 体型更高。保存液类型的效果较弱。各种抽样工作的模拟表明，每个田地少于 10 个陷阱或少于 30 个田地重复，只能区分非常不同的群落。与其他指标相比，发现体型裁剪系统之间差异所需的陷阱更少。Carabid 活动密度和体型，以及蜘蛛属的丰富度，是更好地区分具有最小采样努力的种植系统的变量。为了比较不同种植系统的活动密度和丰富度，需要进行大量抽样工作。选择最合适的陷阱设计、指标和作物是优化采样工作与检测节肢动物群落对栖息地管理反应的能力之间的权衡的主要因素。