Hedgerow restoration promotes pollinator populations and exports native bees to adjacent fields

Published source details Morandin L.A. & Kremen C. (2013) Hedgerow restoration promotes pollinator populations and exports native bees to adjacent fields. Ecological Applications, 23, 829-839.
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This study is summarised as evidence for the following.

	Action	Category
	Pollination: Plant hedgerows Action Link
	Other biodiversity: Plant hedgerows Action Link

Pollination: Plant hedgerows

A replicated, paired, site comparison in May–August 2009–2010 in tomato fields in the Sacramento Valley, California, USA, found more individuals and species of flower-visiting bees and syrphid flies in hedgerows than in weedy field edges, and more individuals and species of bees but not syrphid flies in fields with hedgerows than in fields with weedy edges. Pollinator numbers: More individuals (10 m: 1.2 vs 0.3 individuals/sample; 100 m: 0.8 vs 0.3; 200 m: 0.5 vs 0.2) and more species (10 m: 0.63 vs 0.25 species/sample; 100 m: 0.54 vs 0.22; 200 m: 0.39 vs 0.16) of native bees were found 10–100 m, but not 200 m, into fields with hedgerows than in fields with weedy edges. More honey bees were found 10 m into fields with hedgerows, but there was not a significant difference between these fields in honey bees or syrphid flies at greater distances (honey bees: 10 m: 0.50 vs 0.14 individuals/sample; 100 m: 0.13 vs 0.04; 200 m: 0.20 vs 0.17; syrphid flies: 10 m: 0.63 vs 0.60; 100 m: 0.50 vs 0.67; 200 m: 0.20 vs 0.56). Flower-visitor communities had more species and greater diversity in hedgerows than in weedy edges (bees: 5.7 vs 3.6 species; syrphid flies: 2.7 vs 1.8 species). Twenty bee species were found only in hedgerows, not in weedy edges. Uncommon bee species (species represented by <1% of collected individuals) had larger populations in hedgerows than in weedy edges (6 vs 1 individuals), but uncommon syrphid fly species did not (numbers not reported). Honey bee, native bee, and syrphid fly species had larger populations in hedgerows than in weedy edges (numbers of individuals not reported). The number of flower species and the amount of bare ground did not differ significantly between hedgerows and weedy edges (6 vs 4 species; amount of bare ground not reported), but floral cover was higher and there was more dead wood in hedgerows (amounts not reported). Methods: Native perennial shrubs (305–550 x 7 m), bordered by native perennial grasses (3 m), were planted in 1996–2003 on the edges of six fields (hedgerows) and compared to the unplanted edges of six fields (weedy edges). Insects were netted if they touched the reproductive parts of flowers (in field borders) or they were identified landing on flowers or flying through quadrats (1 m³ quadrats; four minutes/quadrat; three quadrats/field-edge; six quadrats/field).
Other biodiversity: Plant hedgerows

A replicated, paired, site comparison in May–August 2009–2010 in tomato fields in the Sacramento Valley, California, USA, found similar numbers of flower species and similar amounts of plant cover in planted hedgerows and unplanted field edges. Plants: The number of flower species and the amount of bare ground did not differ significantly between hedgerows and weedy edges (6 vs 4 species; amount of bare ground not reported). Methods: Native perennial shrubs (305–550 x 7 m), bordered by native perennial grasses (3 m), were planted in 1996–2003 on the edges of six fields (hedgerows) and compared to the unplanted edges of six fields (weedy edges).