UBC Theses and Dissertations
Harnessing the potential for pollinator conservation in agriculture : semi-natural habitat enhancements in Delta, British Columbia McGregor, Carly Laura
Wild insect communities are key contributors to agriculture through crop pollination. However, many conventional practices in crop production harm insect populations; pesticides have toxic health effects for pollinators, herbicide applications diminish their access to foraging resources, and the frequent disturbance or removal of natural areas destroys habitat. There is growing evidence suggesting that the establishment of functional plant species within semi-natural agricultural areas supports pollinators, either by providing foraging or habitat resources. Planted hedgerows of native shrub and tree species within crop margins, as well as set-aside lands sowed with either grasses or a mix of grasses and flowering herbaceous plants, are examples of such semi-natural habitat enhancements. However, planted hedgerows have shown varying support of pollinating insect communities, and grassland set-asides have not been assessed for their pollinator conservation potential across management types. I conducted a three-phase research study to investigate the conservation potential of enhanced semi-natural areas in the Lower Fraser Valley of British Columbia. First, I assessed pollinator community diversity in three agricultural margins (planted hedgerows, remnant hedgerows, unplanted margins) to evaluate the success of enhanced margins to support pollinators compared to unplanted weedy margins. I found that pollinators visited flowers in hedgerows more often than in weedy margins, but beyond floral visits, I did not observe overall community differences among margin types, suggesting that weedy crop margins are also valuable for pollinators. Second, I evaluated pollinator diversity in three agricultural field types (traditional grassland set-asides, grassland set-asides with added flowers, and active crop control fields) and concluded that both set-asides practices supported pollinators better than crop fields did. Finally, I explored management considerations for enhancement practices, focusing on plant species selection used in seeding set-aside fields or floral strips for pollinators, through a series of literature reviews and expert interviews. Results indicated that floral identity and floral diversity are both important management considerations for floral establishments. These findings provide evidence that semi-natural habitat enhancements supply key resources for insect pollinators in agricultural matrices. The adoption of these practices can promote both the ecological and productive sustainability of agriculture.
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