Planted pollinator habitat in agroecosystems: How does the pollinator community respond?

Pollinators are important both ecologically and economically. Nonetheless, documented pollinator population decline threatens ecosystem functioning and human well-being. In response, conservation methods such as augmented pollinator habitat are becoming popular tools to combat pollinator losses. While previous research has shown added habitat can benefit bee communities, there are still aspects of the habitat implementation that require further research, particularly how this will impact bee communities in real-world settings beyond researcher-led efforts. In our study, we use a 2016 initiative mandating the planting of pollinator habitat on research stations across North Carolina, United States to act as an outdoor laboratory to investigate this exact question. From 2016 to 2018, we found significant increases in bee abundance and diversity. However, these increases depended on the quality of habitat, with areas of higher flower cover and diversity supporting larger, more diverse bee communities. Although the habitats positively supported bee communities, we found that resources within the habitats were lower later in the sampling season, highlighting the need of developing seed mixes that include late-season resources. Weedy plants were documented to establish within the habitats, demonstrating the need for regular upkeep and maintenance of pollinator habitat in order to appropriately support bee communities. It is likely that planting pollinator habitat will not be a one-size-fits-all conservation solution, as bee species can respond differently to some habitat characteristics. Future long-term studies on pollinators will be important as natural fluctuations in bee populations may limit findings and many knowledge gaps on native bees still persist.Funding provided by: North Carolina Department of Agriculture and Consumer ServicesCrossref Funder Registry ID: http://dx.doi.org/10.13039/100015088Award Number: Funding provided by: North Carolina Beekeepers Association*Crossref Funder Registry ID: Award Number: Funding provided by: North Carolina State UniversityCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007703Award Number:Samples were across 3 years (2016–2018). Two sampling methods (bee bowls and hand netting) were used once a month for 4 months (referred to as 'season') each year during peak bloom at the habitat (roughly May – September). Bee bowl samples were collected from all 16 research stations and were placed around the perimeter of the sampling location from 9 am – 3 pm when temperatures were above 15 ºC. Specimens collected by bee bowls were stored in 75% isopropyl alcohol and stored at 4° C until further processing. Hand netting samples were collected at 12 of the 16 research stations by 2–3 people along haphazard, timed transects within the planted habitat for 1 hour, as close to the bee bowl sampling date as possible. Each specimen collected while netting was stored in a microcentrifuge tube, transported back to the lab on ice, and stored at -20 ºC until further processing. At each sampling, a measure of the flower cover and flower diversity was taken, both rated as low, medium, or high. Samples were identified using DiscoverLife and The Bees of North Carolina: An Identification Guide. All specimens are stored in the Tarpy Laboratory at North Carolina State University. Specimens were given trait characteristics at the genus level for their size, nesting material, and pollinator type for use in trait analysis