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Providing evidence to improve practice

Action: Other biodiversity: Plant hedgerows Mediterranean Farmland

Key messages

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Amphibians (0 studies)

Birds (0 studies)

Invertebrates (0 studies)

Mammals (0 studies)

Plants (1 study): One replicated, paired site comparison from the USA found no difference in the number of flower species in hedgerows, compared to weedy field edges.

Reptiles (0 studies)

Implementation options (2 studies): One replicated site comparison from the USA found more plant species in narrow hedgerows, compared to wide hedgerows, and higher plant cover in younger hedgerows, compared to older hedgerows. One replicated site comparison from the USA found higher cover of exotic plants, compared to native plants, in young hedgerows, but not in old hedgerows.

Supporting evidence from individual studies

1 

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).

 

2 

A replicated site comparison in 2009 in farmland in the Sacramento Valley, California, USA, found higher coverage of exotic plants than native plants in newly planted hedgerows. Implementation options: Exotic plants had higher percent cover than native plants in new hedgerows, but not in mature hedgerows (percent cover not reported). Methods: Similar but not identical species of native flowering shrubs and forbs were planted in four mature hedgerows (305–550 m; planted in 1996) and four new hedgerows (350 m x unreported width; planted in 2008). Plants were sampled in fifty quadrats/hedgerow (1 x 1 m).

 

3 

A replicated site comparison in 2009–2010 in the Central Valley, California, USA, found more plant species in narrow compared to wide hedgerows, and higher plant cover in younger compared to older hedgerows. Implementation options: More non-native and native plant species were found in narrow compared to wide hedgerows, and higher non-native and native plant cover were found in younger compared to older hedgerows (numbers of species and amounts of cover not reported). Methods: Thirty-one hedgerows were compared (2–7 x 120–800 m, 0–15 years old). Hedgerows <3 m wide were “narrow” (16 hedgerows), and other hedgerows were “wide” (15 hedgerows). Hedgerows were planted with similar native species. Plants were sampled at the edges (outer 1 m) of narrow and wide hedgerows and in the interior (at least 2 m from the edges) of wide but not narrow hedgerows.

 

Referenced papers

Please cite as:

Shackelford, G. E., Kelsey, R., Robertson, R. J., Williams, D. R. & Dicks, L. V. (2017) Sustainable Agriculture in California and Mediterranean Climates: Evidence for the effects of selected interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.