Declines in native bee populations can limit pollination services that support native plant communities and global food production. Mitigating the impacts on pollinators and ecosystems requires conservation actions that promote biodiversity and remain practical for producers. We investigated plantpollinator interaction networks in working grassland landscapes, managed for cattle production and biodiversity, to advance conservation of pollinators in grazed systems. We compared and plotted interactions at the network level. We then used a regression framework to evaluate the influence of floristic availability on pollinator abundance in our system. Overall, we detected seasonal shifts at the network level, with increased specialization between flowers and bees occurring at the end of the sampling season. Furthermore, the response to floristic resources differed between honey bees (Apis mellifera) and native bees. While honey bee abundance increased with exotic floral abundance, native bee abundance showed no relationship with floral abundance and instead was positively associated with floral richness in our system. These findings could be an indication of seasonal shifts in bee activity and interactions with plants or a response to the subset of available resources in grazed systems. These interpretations, along with the detected difference in resource use between honey bees and native bees, suggest foraging preferences differ between these two groups and could influence conservation and management strategies. Furthermore, it demonstrates a need to consider how management practices could influence bee communities differentially across the growing season and suggests conservation actions should promote native floristic resources to benefit native bees.
Pollinator declines have driven research and increased monitoring efforts. Within North Dakota, USA, our research group initiated research in 2015 on pollinator conservation and management. We synthesized results across five projects, producing 12 publications and providing baseline data on pollinator diversity and rangeland management to improve conservation efforts while land‐sharing with livestock. We detected 76 species of butterflies and ∼318 bee species. Butterfly diversity and relative abundance were driven by floral resources and less exotic plant invasions, with a positive relationship between flowers and pollinators. Invasive forbs were visited by pollinators, primarily honey bees. We also found management influenced vegetation characteristics within pastures, but landscape context was important for determining the specific outcome. Although pollinator abundance did not distinctly respond to management, diversity was affected by regime and grazer type. Using fire and grazing may benefit flowers to support pollinators. Our research will help guide rangeland management decisions that promote land sharing and benefit pollinator conservation efforts.
Core Ideas
We synthesized pollinator data from research conducted over six years in North Dakota.
Pollinator diversity correlated with more forb diversity and less invasive plant species cover.
Pollinator diversity, not abundance, has variable responses to management regime and grazer type.
Fire and grazing may benefit vegetation communities to conserve pollinators in some landscapes.
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