Pollination services from field-scale agricultural diversification may be context-dependent

Published source details Sardiñas H.S. & Kremen C. (2015) Pollination services from field-scale agricultural diversification may be context-dependent. Agriculture, Ecosystems & Environment, 207, 17-25.
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This study is summarised as evidence for the following.

	Action	Category
	Crop production: Plant hedgerows Action Link
	Pollination: Plant hedgerows Action Link

Crop production: Plant hedgerows

A replicated, paired site comparison in 2012–2013 in sunflower fields in the Central Valley, California, USA, found similar crop yields in fields with hedgerows and fields with bare/weedy edges. Crop yield: Similar numbers of sunflower seeds were found in fields with hedgerows and fields with bare/weedy edges (650 seeds/head). Methods: Seeds from three sunflower heads were counted at each of four locations/transect (10, 50, 100, and 200 m from field edges), on two transects/field (2012: 10 fields; 2013: 8 fields). Half of the fields had bare/weedy edges (managed by burning, scraping, or herbicides). Half had hedgerows (3–6 x 250–300 m, 5–12 years old).
Pollination: Plant hedgerows

A replicated, paired site comparison in 2012–2013 in sunflower fields in the Central Valley, California, USA, found more bees, more sunflower-specialist bees, fewer generalist bees, and more bee species in hedgerows than in bare/weedy edges. Crop visitation: Visitation rates to sunflowers were not significantly different in fields with hedgerows than in fields with bare/weedy edges (rates not reported). Pollinator numbers: Bee abundance and species richness were higher in hedgerows than in bare/weedy edges (abundance: 17 vs 6 individuals/sample; richness: 5 vs 2 species/sample). More sunflower-specialist bees, but fewer generalist bees, were found in hedgerows than in bare/weedy edges (specialists: 0.6 vs 0.1 relative abundance; generalists: 0.0 vs 0.3). Methods: In field edges, when >90% of sunflower heads were blooming in adjacent fields, bees were netted for 16 minutes/field (2012: 10 fields; 2013: 8 fields), and bees that touched the reproductive parts of flowers were counted for 2 minutes/plot in 8 plots/field (visitation rates). Half of fields had bare/weedy edges (managed by burning, scraping, or herbicides). Half had hedge rows (3–6 x 250–300 m, 5–12 years old). Sunflower specialists and generalists were netted in 26 hedgerows and 21 bare/weedy edges (one hour/sample; five samples in April–August 2012–2013).