IntroductionNative bee communities of temperate forests are conventionally sampled from the understory, yet there is growing evidence that bee assemblages in forest canopies are distinct from those in the understory. Therefore, conventional approaches to quantify forest bee–habitat relationships may not comprehensively characterize forest bee communities.MethodsTo examine this, we sampled bees 1–26 m from ground level at 5-m increments at 47 locations in forests located in western Massachusetts, USA. We evaluated bee abundance and species richness responses to a suite of environmental factors measured in the understory with linear and segmented regression comparing four bee sampling strategies: (1) understory sampling only, (2) understory and midstory, (3) understory and canopy, and (4) all strata combined.ResultsWe found that not sampling higher strata underestimated bee abundance and species richness, and linear models had less ability to explain the data when bees of higher strata were included. Among strategies, responses analyzed linearly differed in magnitude due to overall differences in abundance and species richness, but segmented regressions showed relationships with understory characteristics that also differed in slope, which would alter interpretation.DiscussionCollectively, our findings highlight the value of including vertically stratified sampling strategies throughout the flight season to fully characterize native bee and other pollinator communities of forests.

中文翻译：

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对林下、中层和树冠进行采样对于充分描述温带森林的本地蜜蜂群落及其动态环境关系是必要的

介绍温带森林的本地蜜蜂群落通常是从林下取样，但越来越多的证据表明森林冠层中的蜜蜂群落与林下的蜜蜂群落不同。因此，量化森林蜜蜂与栖息地关系的传统方法可能无法全面描述森林蜜蜂群落的特征。方法为了检验这一点，我们在美国马萨诸塞州西部森林的 47 个地点以 5 米的增量对距离地面 1-26 米的蜜蜂进行了采样。我们通过线性和分段回归评估了蜜蜂丰度和物种丰富度对林下测量的一系列环境因素的响应，比较了四种蜜蜂采样策略：（1）仅林下采样，（2）林下和中层，（3）林下和冠层， （4）所有阶层合并。结果我们发现，不采样较高阶层会低估蜜蜂丰度和物种丰富度，并且当包括较高阶层蜜蜂时，线性模型解释数据的能力较差。在策略中，由于丰度和物种丰富度的总体差异，分析的响应在幅度上存在线性差异，但分段回归显示与坡度也不同的林下特征的关系，这将改变解释。 讨论总的来说，我们的研究结果强调了包括垂直分层抽样的价值整个飞行季节的策略，以充分描述森林中的本地蜜蜂和其他授粉昆虫群落。