Within agricultural landscapes, native bees often rely on limited natural and seminatural lands to provide the majority of the food and nesting resources that sustain them. To understand better how management can affect pollinators in these seminatural areas, we compared how sheep or cattle herbivory influenced floral resources and bee communities in low-diversity, former Conservation Reserve Program (CRP) pastures managed with patch-burn grazing. We sampled bee communities and floral resources three times per season in 2017, 2018, and 2019. We used plant-pollinator line transect sampling and collected bees and counted all flowering stems within 1 m. Across all years, we found that floral abundance, floral richness, floral diversity (Simpson’s) and bee richness and abundance were significantly higher in cattle pastures compared to sheep. In cattle pastures, 46 native bee species plus honey bees interacted with 25 of 68 available flowering forbs. In sheep pastures, we recorded 14 native bee species and honey bees interacted with 10 of 34 flowering species. Native bee abundance and native bee richness were best explained by models that included an interaction of floral richness and year. Overall, our results suggest that season-long sheep grazing in low-diversity grasslands greatly reduces available floral resources and correlates with much lower bee abundance and native bee diversity. Given the importance of pollinators to natural and agricultural systems, it is imperative that we take proactive actions to increase forb richness and native flower abundance in seminatural lands to maintain a more diverse and resilient bee community that can continue to support pollination services and global food security.

中文翻译：

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牛羊不同地改变花卉资源和工作景观中的本地蜜蜂群落

在农业景观中，本土蜜蜂通常依靠有限的自然和半自然土地来提供维持它们的大部分食物和筑巢资源。为了更好地了解管理如何影响这些半自然地区的传粉媒介，我们比较了羊或牛食草如何影响低多样性、前保护区计划 (CRP) 牧场中的花卉资源和蜜蜂群落，这些牧场采用斑块烧伤放牧方式管理。我们在 2017 年、2018 年和 2019 年每个季节对蜜蜂群落和花卉资源进行了 3 次采样。我们使用植物传粉线样带采样并收集蜜蜂，并对 1 m 内的所有开花茎进行计数。多年来，我们发现与绵羊相比，牛牧场的花卉丰度、花卉丰富度、花卉多样性（辛普森氏）以及蜜蜂的丰富度和丰度明显更高。在牛牧场中，46 种本地蜜蜂和蜜蜂与 68 种可用开花植物中的 25 种相互作用。在绵羊牧场，我们记录了 14 种本地蜜蜂物种，蜜蜂与 34 种开花物种中的 10 种相互作用。包括花卉丰富度和年份相互作用的模型最好地解释了原生蜜蜂丰度和原生蜜蜂丰富度。总体而言，我们的研究结果表明，在低多样性草原放牧一季绵羊大大减少了可用的花卉资源，并与低得多的蜜蜂丰度和本地蜜蜂多样性相关。鉴于传粉媒介对自然和农业系统的重要性，