Data from: Bee communities along a prairie restoration chronosequence: similar abundance and diversity, distinct composition

Recognition of the importance of bee conservation has grown in response to declines of managed honey bees and some wild bee species. Habitat loss has been implicated as a leading cause of declines, suggesting that ecological restoration is likely to play an increasing role in bee conservation efforts. In the Midwestern USA, restoration of tallgrass prairie has traditionally targeted plant community objectives without explicit consideration for bees. However, restoration of prairie vegetation is likely to provide ancillary benefits to bees through increased foraging and nesting resources. We investigated community assembly of bees across a chronosequence of restored eastern tallgrass prairies and compared patterns to those in control and reference habitats (old fields and prairie remnants, respectively). We collected bees for three years and measured diversity and abundance of in-bloom flowering plants, vegetation structure, ground cover, and surrounding land use as predictors of bee abundance and bee taxonomic and functional diversity. We found that site-level variables, but not site type or restoration age, were significant predictors of bee abundance (bloom diversity: p = 0.004, bare ground cover: p = 0.02) and bee diversity (bloom diversity: p = 0.01). There were significant correlations between overall composition of bee and blooming plant communities (mantel test: p = 0.002), and both plant and bee assemblages in restorations were intermediate between those of old fields and remnant prairies. Restorations exhibited high bee beta diversity, i.e., restored sites’ bee assemblages were taxonomically and functionally differentiated from each other. This pattern was strong in younger restorations (< 20 years old), but absent from older restorations (> 20 years), suggesting restored prairie bee communities become more similar to one another and more similar to remnant prairie bee communities over time with the arrival of more species and functional groups of bees. Our results indicate that old fields, restorations, and remnants provide habitat for diverse and abundant bee communities, but continued restoration of old fields will help support and conserve bee communities more similar to reference bee communities characteristic of remnant prairies.

随着管理式蜂群（managed honey bees）与部分野生蜂类种群数量下降，人们对蜜蜂保护重要性的认知日益提升。栖息地丧失被认为是蜂群衰退的首要诱因，这表明生态修复（ecological restoration）有望在蜜蜂保护工作中发挥愈发重要的作用。在美国中西部地区，传统上东部高草草原（eastern tallgrass prairie）修复工作多以达成植物群落目标为导向，未明确考虑蜜蜂种群需求。然而，草原植被修复可通过增加觅食与筑巢资源，为蜜蜂提供附带益处。本研究针对一系列具有演替时间序列的东部高草草原修复样地，探究了蜜蜂的群落构建规律，并将其与对照生境（弃耕地，old fields）及参照生境（原生草原残遗样地，prairie remnants）的蜜蜂群落格局展开对比。研究历时三年采集蜂样，并测定了盛花期开花植物的多样性与多度、植被结构、地表覆盖及周边土地利用格局，以此作为蜜蜂多度、蜜蜂分类学多样性与功能多样性的预测因子。研究发现，样地水平变量可显著预测蜜蜂多度（开花植物多样性：p = 0.004，裸地覆盖度：p = 0.02）与蜜蜂多样性（开花植物多样性：p = 0.01），而样地类型或修复年限则无显著预测效果。蜜蜂与开花植物群落的整体组成间存在显著相关性（曼特尔检验（Mantel test）：p = 0.002），且修复样地中的植物与蜜蜂群落组成均介于弃耕地与原生草原残遗样地之间。修复样地展现出较高的β多样性（beta diversity），即不同修复样地的蜜蜂群落在分类学与功能层面均存在分化。该模式在修复年限不足20年的样地中尤为显著，但在修复年限超过20年的样地中则不复存在，这表明随着时间推移，更多蜜蜂类群与功能群的迁入，修复草原的蜜蜂群落会逐渐趋于同质化，且愈发接近原生高草草原残遗样地的蜜蜂群落特征。本研究结果表明，弃耕地、修复样地与原生残遗样地均可为多样且丰富的蜜蜂群落提供栖息生境，但持续对弃耕地开展修复工作，将有助于构建并保护更接近原生高草草原典型参照蜜蜂群落的蜂群体系。