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Native bee diversity within urban gardens in Kelowna, British Columbia

University of British Columbia

Habitat loss and fragmentation caused by urbanization can be detrimental to urban bee populations. Bee-friendly gardens containing suitable plants and substrates may mitigate these impacts by providing forage and nesting resources. However, the efficacy of such gardens may depend on characteristics of the broader landscape, including its degree of urbanization. Between 2017 and 2019, 350+ landowners throughout Kelowna, British Columbia, created pollinator-friendly gardens as part of the successful “Border Free Bees” initiative. Focusing on one of Canada’s bee diversity hotspots (400+ native species, 38+ genera), I addressed the following objectives: (i) to assess native bee diversity within bee-friendly urban gardens; (ii) to explore how the alpha diversity (richness) and composition of native bee genera varied relative to (a) plant diversity within a garden, (b) garden size, and (c) urbanization measured at a broader spatial scale; and (iii), to quantify the percentage of garden plants among those recommended by the Bee Ambassador program. Thirty-three gardens were selected based on a stratified sampling design ensuring coverage of a broad range of degree of urbanization. Between June and August, 2019, I deployed pan-traps five times for a two-day period in each garden. I trapped an average of 58.47 individuals at each garden (CI = 43.25 - 73.69), and an average of 7.9 genera per garden (95% CI = 7.09–8.66), with 19 genera observed in total, accounting for half of the genera known to exist within this ecoregion. Members of the Halictidae family accounted for 66.4% of total abundance. Using generalized linear models and redundancy analysis, I found no association between the local (garden) characteristics and bee richness and composition, nor were these diversity measures associated with urbanization. On average, 47.3% (95% CI = 40.36–54.17) of plants within gardens were among the recommended species. My study is the first to evaluate urban bee diversity within the Okanagan, and my findings add to a body of literature revealing inconsistent effects of garden and landscape-scale characteristics on bee diversity.

Text

2021-01-06

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/76960

Earth and Environmental Sciences

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/