Kammerer, M. | bioRxiv Science

bioRxiv2022

Seasonal bee communities vary in their responses local and landscape scales: implication for land managers

ContextThere is great interest in land management practices for pollinators; however, a quantitative comparison of landscape and local effects on bee communities is necessary to determine if adding small habitat patches can increase bee abundance or species richness. The value of increasing floral abundance at a site is undoubtedly influenced by the phenology and magnitude of floral resources in the landscape, but due to the complexity of measuring landscape-scale resources, these factors have been understudied. ObjectivesTo address this knowledge gap, we quantified the relative importance of local versus landscape scale resources for bee communities, identified the most important metrics of local and landscape quality, and evaluated how these relationships vary with season. MethodsWe studied season-specific relationships between local and landscape quality and wild-bee communities at 33 sites in the Finger Lakes region of New York, USA. We paired site surveys of wild bees, plants, and soil characteristics with a multi-dimensional assessment of landscape composition, configuration, insecticide toxic load, and a spatio-temporal evaluation of floral resources at local and landscape scales. ResultsWe found that the most relevant spatial scale varied by season. Spring bees depended on landscape resources, but summer bees responded more to local quality, implying that site-level management is most likely to be successful in supporting summer bees. Semi-natural habitats, including forests, wetlands, and other aquatic habitats, were particularly important for spring bees. ConclusionsBy considering spatial and temporal variation in resources, we developed season-specific recommendations to improve habitat quality for wild bees and offset manifold stressors threatening these essential pollinators.

ecology↗

bioRxiv2021

Putting pesticides on the map for pollinator research and conservation

Wild and managed pollinators are essential to food production and the function of natural ecosystems; however, their populations are threatened by multiple stressors including pesticide use. Because pollinator species can travel hundreds to thousands of meters to forage, recent research has stressed the importance of evaluating pollinator decline at the landscape scale. However, scientists and conservationists ability to do this has been limited by a lack of accessible data on pesticide use at relevant spatial scales and in toxicological units meaningful to pollinators. Here, we synthesize information from several large, publicly available datasets on pesticide use patterns, land use, and toxicity to generate novel datasets describing pesticide use by active ingredient (kg, 1997-2017) and aggregate insecticide load (kg and honey bee lethal doses, 1997-2014) for state-crop combinations in the contiguous U.S. Furthermore, by linking pesticide datasets with land-use data in the contiguous United States, we describe a method to map pesticide indicators at spatial scales relevant to pollinator research and conservation.

ecology↗