Other biodiversity: Plant flowers

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 3
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How is the evidence assessed?

Effectiveness

40%
Certainty

20%
Harms

20%

Calculating overall effectiveness category

Study locations

Key messages

Amphibians (0 studies)

Birds (0 studies)

Invertebrates (0 studies)

Mammals (0 studies)

Plants (2 studies): One replicated, paired, controlled study from Italy found similar numbers of plant species in planted flower strips and unplanted field margins, but found higher plant diversity in unplanted margins. One replicated study from the USA found that most flower species persisted for at least two years after planting.

Reptiles (0 studies)

Implementation options (2 studies): One replicated study from the USA found that more plant species persisted in flower strips when twice as many seeds were sown, but there was no further increase in persistence at higher seeding rates. One replicated, randomized, controlled study from Spain found that tillage had inconsistent effects on the emergence of planted flowers.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, paired, controlled study in 2011–2012 in tomato fields in Tuscany, Italy, found similar numbers of plant species in planted flower strips, compared to unplanted field margins, but found higher plant diversity in unplanted margins. Plants: Similar numbers of plant species were found in planted and unplanted margins (numbers of species not reported). However, a higher turnover in species was found between unplanted margins than between planted margins (data reported as beta-diversity). Methods: In each of eight tomato fields, plants were sampled in each of two field margins (one with flower strips, one without, 3 x 25 m each), in five 1 x 1 m quadrats/field margin, in early August.
Study and other actions tested
Referenced paper
Balzan M.V. & Moonen A. (2014) Field margin vegetation enhances biological control and crop damage suppression from multiple pests in organic tomato fields. Entomologia Experimentalis et Applicata, 150, 45-65.
A replicated study in 2008–2010 in farmland in the Central Valley, California, USA, found that a higher percentage of flower species persisted over time in flower plots that were planted with higher amounts of seed. Plants: Eight of nine species persisted for two years. Six species persisted for three years. Implementation options: Over the two years that followed planting, a higher percentage of species persisted in plots that were planted with two to four times as much seed (2x–4x) as the plots that were planted with the least seed (1x: 17–60%; 2x: 33–74%; 4x: 35–77%), but there was not a significant difference between the plots with 2x and 4x. The amount of seed planted had a significant effect on the percentage cover of plants, but it was not clear which treatments were significantly different from one another (data reported as log aggregate forb cover). Methods: Nine plots (1 x 8 m) were sown with the seeds of nine flower species in each of six hedgerows.
Study and other actions tested
Referenced paper
Wilkerson M.L., Ward K.L., Williams N.M., Ullmann K.S. & Young T.P. (2014) Diminishing returns from higher density restoration seedings suggest trade-offs in pollinator seed mixes. Restoration Ecology, 22, 782-789.
A replicated, randomized, controlled study in 2011–2012 in a barley field near Madrid, Spain, found that more seedlings of five planted flower species, but fewer seedlings of one planted flower species, emerged after no tillage, compared to shallow tillage. Implementation options: A higher density of seedlings emerged after no tillage, compared to shallow tillage, in Calendula arvensis (2011: 4,523 vs 2,817 plants/m²; 2012: 1,223 vs 231), Phacelia tanacetifolia (2011: 318 vs 226; 2012: 116 vs 2), Centauria cyanus (2012: 190 vs 59), Diplotaxis tenuifolia (2012: 153 vs 5), and Echium plantagineum in 2012 (236 vs 2) but not in 2011 (230 vs 235). A lower density of seedlings emerged after no tillage, compared to shallow tillage, in Coriandrum sativum in 2011 (16 vs 314 plants/m²), but not in 2012 (0 vs 2). Similar densities of seedlings emerged after no tillage, compared to shallow tillage, in Borago officinalis (2011: 27 vs 27 plants/m²; 2012: 20 vs 2). Methods: For each of seven flower species, there were three plots (1.3 x 1.3 m). In July, half of each plot was tilled, and half was not. In January, seedlings were counted in quadrats (25 x 25 cm).
Study and other actions tested
Referenced paper
Barbir J., Badenes-Pérez F.R., Fernández-Quintanilla C. & Dorado J. (2015) The attractiveness of flowering herbaceous plants to bees (Hymenoptera: Apoidea) and hoverflies (Diptera: Syrphidae) in agro-ecosystems of central Spain. Agricultural and Forest Entomology, 17, 20-28.

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.

Where has this evidence come from?

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This Action forms part of the Action Synopsis:

Mediterranean Farmland

Related Actions

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Water: Exclude grazers Action Link	Unknown effectiveness (limited evidence)	6	Synopsis Link
Soil: Use no tillage in arable fields Action Link	Likely to be beneficial	40	Synopsis Link
Pollination: Plant or maintain ground cover in orchards or vineyards Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link