Data from: The challenge of accurately documenting bee species richness in agroecosystems: bee diversity in eastern apple orchards

Bees are important pollinators of agricultural crops, and bee diversity has been shown to be closely associated with pollination, a valuable ecosystem service. Higher functional diversity and species richness of bees have been shown to lead to higher crop yield. Bees simultaneously represent a mega-diverse taxon that is extremely challenging to sample thoroughly and an important group to understand because of pollination services. We sampled bees visiting apple blossoms in 28 orchards over 6 years. We used species rarefaction analyses to test for the completeness of sampling and the relationship between species richness and sampling effort, orchard size, and percent agriculture in the surrounding landscape. We performed more than 190 h of sampling, collecting 11,219 specimens representing 104 species. Despite the sampling intensity, we captured <75% of expected species richness at more than half of the sites. For most of these, the variation in bee community composition between years was greater than among sites. Species richness was influenced by percent agriculture, orchard size, and sampling effort, but we found no factors explaining the difference between observed and expected species richness. Competition between honeybees and wild bees did not appear to be a factor, as we found no correlation between honeybee and wild bee abundance. Our study shows that the pollinator fauna of agroecosystems can be diverse and challenging to thoroughly sample. We demonstrate that there is high temporal variation in community composition and that sites vary widely in the sampling effort required to fully describe their diversity. In order to maximize pollination services provided by wild bee species, we must first accurately estimate species richness. For researchers interested in providing this estimate, we recommend multiyear studies and rarefaction analyses to quantify the gap between observed and expected species richness.蜜蜂是农作物的关键传粉媒介，已有研究证实蜜蜂多样性与传粉服务这一重要生态系统服务存在紧密关联。蜜蜂的功能多样性与物种丰富度越高，农作物产量往往也随之提升。蜜蜂既是一类高度多样的类群，其全面采样极具挑战性，同时又因提供传粉服务而成为极具研究价值的类群。本研究历时6年，对28个苹果园中的访花蜜蜂开展了系统性采样。我们采用物种稀疏分析（species rarefaction analyses），用以检验采样完整性，并探究物种丰富度与采样强度、果园规模及周边景观农业用地占比之间的关联。本次采样累计时长超190小时，共采集到11219号标本，涵盖104个蜜蜂物种。尽管采样强度较高，但在超过半数的采样点中，仅采集到预期物种丰富度的75%以下。其中多数采样点的蜜蜂群落组成在年际间的差异，显著高于不同采样点之间的差异。物种丰富度受周边农业用地占比、果园规模及采样强度的影响，但本研究未发现能够解释观测物种丰富度与预期物种丰富度之间差异的影响因素。家养蜜蜂（honeybee）与野生蜜蜂（wild bee）之间的竞争并未表现为影响因素，本研究未发现二者的丰度间存在显著相关性。本研究表明，农业生态系统中的传粉动物群落兼具物种多样性与全面采样的挑战性。研究证实，蜜蜂群落组成存在显著的时间变异，且不同采样点达到物种多样性完整描述所需的采样强度差异悬殊。若要最大化野生蜜蜂物种所提供的传粉服务，首先需要准确估算其物种丰富度。针对希望开展此类物种丰富度估算的研究人员，我们建议采用多年期研究结合物种稀疏分析的方法，量化观测物种丰富度与预期物种丰富度之间的缺口。