Browsing by Author "Cariveau, Dan"

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    Cost-Effective Roadside Revegetation Methods to Support Insect Pollinators
    (Minnesota Department of Transportation, 2022-08) Mitchell, Timothy; Verhoeven, Michael; Darst, Ashley; Evans, Elaine; Cariveau, Dan; Snell-Rood, Emilie
    Roadsides contain promising habitat for insect pollinators, yet roadside restorations can be expensive and are rarely evaluated for effectiveness. Where do we establish pollinator-friendly revegetation to maximize benefits? How effective are current revegetation practices at providing habitat for pollinators? We address these questions with two studies. Chapter 2 examines the impact of roadside-adjacent habitat that has been identified as pollinator-friendly for bumble bees. We use pollinator habitat maps to examine associations between the amount of nearby pollinator-friendly habitat and bumble bees (abundance and richness). We also regroup land covers to more specifically align with bumble bee habitat needs and compare the ability of both land cover categorizations to predict bumble bee metrics. This study can help refine predictors in mapping efforts to prioritize locations for pollinator habitat enhancements. Chapters 3 and 4 combine detailed insect and floral surveys of sites with known revegetation history to test efficacy of current revegetation methods for providing habitat for insect pollinators. We show which plants establish after seeding and how communities change as they age. We find that native flowering plants are more likely to establish in roadsides when they are planted, but native and non-native seeded sites converge in the plant community through time. Bumble bee and butterfly abundance and diversity is tied to flowering plant abundance and diversity, regardless of their status as native plants. This work identifies where pollinator-friendly restorations should be implemented and how current seeding practices could be modified to improve benefits to pollinators while reducing costs.
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    Monitoring and Habitat Assessment of Declining Bumble Bees in Roadsides in the Twin Cities Metro Area of Minnesota
    (University of Minnesota Center for Transportation Studies, 2019-06) Evans, Elaine; Boone, Michelle; Cariveau, Dan
    Several bumble bee species have declined dramatically, including the endangered rusty-patched bumble bee, Bombus affinis. Roadsides offer a unique opportunity to increase habitat for these declining species. The objectives of this study are to: (1) characterize the bumble bee community and floral availability within roadsides in the Minneapolis and Saint Paul, Minnesota, metro area, (2) estimate detection probabilities and occupancy for bumble bees using occupancy modeling, (3) determine the effort needed to detect rusty-patched bumble bees, and (4) examine the relationship of the bumble bee community to the surrounding landscape. We use rapid and broad-scale sampling at randomly selected locations. Despite overall low floral abundance, many bumble bee species, including rare and declining species, use roadsides. Occupancy models predict rusty-patched bumble bees occupy 4% of sites, with a 30% chance of detection if it is at the site. We recommend performing nine surveys in a single season to be 95% sure that B. affinis is detected if it is there. Bumble bee abundances and species numbers increase with more wooded area and floral cover. Crops are negatively associated with bee abundance, species numbers, and the presence of rare bumble bees. Our management recommendations for roadsides to support rare and declining bumble bees are: (1) incorporate additional bumble bee forage, (2) when weed control requires elimination of flowering plants, replace with bumble bee forage, (3) use our estimates for occupancy and abundance as a baseline to assess conservation efforts for bumble bees within roadsides in the metropolitan area of Minneapolis and Saint Paul.