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Individual study: Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States

Published source details

Williams N.M., Ward K.L., Pope N., Isaacs R., Wilson J., May E.A., Ellis J., Daniels J., Pence A., Ullmann K. & Peters J. (2015) Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States. Ecological Applications, 25, 2119-2131


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Pollination: Plant flowers Mediterranean Farmland

A replicated, controlled study in 2010–2011 in farmland in the Central Valley, California, USA, found more wild bees and bee species in perennial flower plantings, compared to annual flower plantings or unplanted controls, and more wild bees in species-rich but not species-poor annual plantings, compared to unplanted controls. Pollinator numbers: More wild bees were found in perennial flower plantings, compared to unplanted plots (525–775 vs 75–100 individuals). More wild bees were found in ten-species annual plots, compared to unplanted plots (175–250 vs 75–100 individuals), but no difference was found between five-species annual plots and unplanted plots (100–175 vs 75–100). More bee species were found in perennial plots, compared to unplanted plots (17–21 vs 8–13 bee species), but not in annual plots, compared to unplanted plots (10–15 vs 8–13). More honey bees Apis mellifera were found on annual or mixed compared to unplanted plots (450–750 vs 25–75 individuals). More honey bees were found on perennial compared to unplanted plots in 2011 (650 vs 25 individuals) but not in 2010 (250 vs 75). More bumblebees Bombus spp. were found on annual or perennial compared to unplanted plots (5–50 vs 0 individuals), and mixed plots (5–25) were not significantly different from annual, perennial, or unplanted plots. Similar numbers of syrphid flies were found in different plots (5–40 individuals). Implementation options: More wild bees were found in perennial flower plots, compared to annual (525–775 vs 100–225 individuals), but not compared to mixed plots with annuals and perennials (525–775 vs 525–650). More bee species were found in eight-species perennial plots, compared to five- or ten-species annual plots (20–21 vs 10–15 bee species), and in five-species perennial plots, compared to five-species annual plots (17 vs 10–12), but not in five-species perennial plots, compared to ten-species annual plots (17 vs 12–15), or in perennial compared to mixed plots (17–21 vs 18–21). Methods: Six flower plots (ten-species annual, five-species annual, eight-species perennial, five-species perennial, mixed, and control) were planted on each of three sites. Plots were 3 x 15 m. Flower visitors were counted if they touched the reproductive parts of flowers (20 minutes/sample, six samples/plot).