Providing evidence to improve practice

Action: Plant grass buffer strips/margins around arable or pasture fields Farmland Conservation

Key messages

  • Nineteen studies from Finland, the Netherlands, Sweden and the UK (including seven replicated controlled studies of which two were randomized, and three reviews), found that planting grass buffer strips (some margins floristically-enhanced) increased arthropod abundance, species richness and diversity. A review found grass margins benefited bumblebees and some other invertebrates but did not distinguish between the effects of several different margin types.
  • Nine studies from the UK (including seven replicated studies of which two were controlled, and two reviews) found that planting grass buffer strips (some margins floristically-enhanced) benefits birds, resulting in increased numbers, densities, species richness and foraging time.
  • Seven studies from the Netherlands and the UK (all replicated of which four were controlled and two randomized), found that planting grass buffer strips (some margins floristically-enhanced) increased the cover and species richness of plants. A review found grass margins benefited plants but did not distinguish between the effects of several different margin types.
  • Five studies from Finland and the UK (including two replicated, controlled trials and a review), found that planting grass buffer strips benefits small mammals: including increased activity and numbers.
  • Six studies from the Netherlands and the UK (including three replicated, controlled trials) found that planting grass buffer strips had no clear effect on insect numbers, bird numbers or invertebrate pest populations. A replicated site comparison found sown grassy margins were not the best option for conservation of rare arable plants.

Supporting evidence from individual studies

1 

A replicated, controlled, randomized study in the UK (Marshall et al. 1994) found that plant cover was higher in margins sown with grass or grass/wildflower mixtures than those naturally regenerated, but plant diversity tended to be lower with grass-only seed mixtures. Margins were created in each field and divided into six plots (4 x 30 m).  Each was (randomly) sown with a seed mixture: grass, low cost mix (3 grass: 7 herb species), alkaline soil (6: 16), neutral soil (5: 15), acid soil (6: 16) and one natural regeneration.  Plots were divided into 10 m sub-plots, which were either unmanaged, cut once or received grass herbicide. The same study is reported in West & Marshall (1996).

Additional references:

West T.M. & Marshall E.J.P. (1996) Managing sown field margin strips on contrasted soil types in three environmentally sensitive areas. Aspects of Applied Biology, 44, 269-276.

2 

A replicated, controlled study in 1995-1996 in Cambridgeshire, UK (Clarke et al. 1997) found that more bird individuals (average 20% of all individual birds recorded) and more bird species (average 56% of all bird species counted in 1995-1996) used the sown set-aside strips than the adjacent crop area (average 7% individuals and 33% species) in both years. Across all habitats 44 species were recorded in 1995 and 31 spp. in 1996. However, the highest proportions of both individuals and species were recorded in field boundaries (average 68% of all individuals and 8% of all spp.). The highest species richness was found in the most species rich grass mix. The seed mixture ‘Tübinger Mischung’ designed to provide nectar for bees (Apidae) and containing only wildflowers attracted the largest number of birds but the lowest number of bird species. Yellowhammer Emberiza citrinella, red-legged partridge Alectoris rufa and pheasant Phasianus colchicus were the most recorded species in set-aside strips. Note that no statistical analyses were performed on these data. Five seed mixtures were sown on 15 set-aside areas (minimum 20 m x 100 m) in autumn 1993 and 1994. Seed mixtures contained only grass species (three mixes of three to six species), a mix of grasses and wildflowers (six grass and eight wildflower species) or only wildflowers (11 species). Birds were recorded during 15 minute point counts on 10 occasions between June and September 1995 and July and October 1996. Individual bird locations were recorded in three categories: field boundary, set-aside strip or crop. After each count, the strips were walked to flush any birds present but not visible during the count.

3 

A replicated study in summer 1996 in Gloucestershire, UK (Hopkins & Feber 1997), found higher overall butterfly abundance and species richness in plots sown with a wild grass/flower seed mixture (four grasses, five wildflowers) than in naturally regenerated plots. Vegetation removal had no effect on butterfly abundance, but overall species richness was lower in plots cut for silage in June and grazed by cattle in July. Plant species richness was on average higher in sown than naturally regenerated plots (23 vs 19 species). Vegetation removal had no effect on plant species richness but uncut/ungrazed plots had more wildflower species in flower in July. In September 1994, twenty 50 m long experimental plots were created in the margins of two adjoining organic fields. Ten plots were sown, ten were allowed to naturally regenerate. Presence of all sown and unsown plant species were recorded as well as wildflower species in flower (May and July 1996). Butterflies were monitored weekly June-September along a transect route.

4 

A replicated trial in the Netherlands (Kleijn et al. 1997) found that 4 m-wide field margins sown with rye grass Lolium perenne had fewer plant species than margins left to naturally regenerate or sown with wildflowers two years after establishment. On average there were 5.9 plant species/0.25 m2 in grass-sown margins, compared with 8.6 in naturally regenerated margins and 13.7 in margins sown with 30 non-grass wildflower species. Two prominent arable weeds, creeping thistle Cirsium arvense and couch grass Elymus repens both had lower biomass in the grass-sown margins than in naturally regenerated margins (8 g/m2 and 9 g/m2 respectively in grass-sown margins, 33 g/m2 and 28 g/m2 in naturally regenerated plots). Wildflower-sown margins had similar couch grass biomass to the grass-sown plots, but much lower creeping thistle biomass (0.1 g/m2 in wildflower margins). In 1993, 27 experimental plots (8 x 4 m) were established on the boundaries of three arable fields. There were three replicates of each treatment on each field. All plots were mown once a year, without removing cuttings. Plant biomass and number of species were measured in eight 0.5 m x 0.5 m plots on a single transect line across each margin, in August 1995.

5 

A replicated, controlled, randomized study from 1987 to 1991 in Oxfordshire, England (Smith et al. 1997) found that a grass ley sown with a species rich mix of grasses and wildflowers retained more sown plant species and had more naturally regenerating species than a conventionally sown ley. Loss of sown species increased at high fertilizer levels. Numbers of sown and naturally regenerating plant species were lower under a silage than a hay cutting regime. The more species-rich ley was less productive and so easier to manage by infrequent mowing. Field margins (7-9 m wide) were established in 1987 around three arable fields. In 1988 they were divided into 50 m-long plots and half (randomly assigned) in each field were sown with each grass ley mix: conventional (two grass and one clover Trifolium species) or a more species-rich mix, comprising six indigenous grasses and three forbs (excluding rye grass Lolium perenne and white clover T. repens).

6 

A replicated study in summer 1996 in central Germany (Weiss & Buchs 1997) found that spider (Araneae) species richness in plots sown with a grass mixture (36 spider species) was lower than plots sown with lacy phacelia Phacelia tanacetifolia and Egyptian clover Trifolium alexandrinum (40 spider spp.), but higher than in plots sown with lacy phacelia, buckwheat Fagopyrum esculentum, common sunflower Helianthus annuus and common mallow Malva sylvestris (30 spider spp.). Spider abundance in grass mix plots (126 and 65 individuals in pitfall traps and photoeclectors respectively) was lower than in plots containing sundial lupine Lupinus perennis and common vetch Vicia sativa (155 and 124 individuals in pitfall traps/photoeclectors), but only significantly lower in the eclector samples. Note that most results in this study are not statistically tested. Eight different types of strips with three replicates each were tested: six seed mixtures containing mainly flowering plants (1-12 species), one mixture containing mainly grasses (red fescue Festuca rubra (64%), perennial rye grass Lolium perenne (25%) plus white clover T. repens (10%)) and one naturally regenerated treatment. Spiders were sampled using two pitfall traps and two photoeclectors in each plot.

7 

A replicated, controlled, randomized study in Finland (Huusela-Veistola 1998) found that spider (Araneae) abundance was higher in perennial grass/clover Trifolium spp. strips than in the crop (approximately 1,200-3,000 vs 400-900 spiders respectively). Wolf spiders (Lycosidae) dominated in grass strips (57-77% of total catches). Money spiders (Linyphiidae) were also more common in grass strips than in the crop. Total spider catches including wolf spiders decreased with distance into the crop. Perennial grass/clover strips 12 m wide were sown with a mixture of timothy Phleum pratense, meadow fescue Festuca pratensis, red clover T. pratense, and white clover T. repens at the ends of 24 plots in 1991. Spiders were sampled with a pitfall trap in the centre of the grass strip and at 12, 66 and 120 m into each plot from the grass strip 8-10 times (each trapping period lasting one week) between sowing and harvest (1992-1994).

8 

A replicated study in the summers of 1997-1998 in three regions across the UK (Barker & Reynolds 1999) found that the total percentage of grass cover in planted grass strips affected the abundance of sawfly (Symphyta) larvae positively. Sawfly larvae numbers were found to increase with strip age and to decrease with the amount of cocksfoot Dactylis glomerata (both trends non-significant). There was no difference in the average catch of sawfly larvae between beetle banks and strips planted along existing field margins. Numbers of insects used by gamebirds as chick food increased with strip age and area, but there was also a significant difference between farms. There was a non-significant trend for chick-food insect numbers to increase with the proportion of red fescue Festuca rubra. Cocksfoot, red fescue and perennial rye grass Lolium perenne were the predominant grasses in most strips, being most common in 35, 25 and 17 strips respectively. A total of 116 strips were sampled on 32 farms. Grass strips had been established 0.5-12 years previously, both along pre-existing field margins and across cropped fields (beetle banks). Invertebrates were sampled by sweep-netting at the base of the vegetation in mid-June to mid-July. Percentage cover of all plant species and vegetation height was measured in 0.25 m2 quadrats.

9 

A replicated study from 1992 to 1998 in England (Brown 1999) found that small mammal activity was significantly greater in field margins than in open fields in both organic (142 vs 86 mammals respectively) and conventional systems (139 vs 78). There was no difference between systems. The same trend was seen in both systems for wood mouse Apodemus sylvaticus (margins: 40-80%; field: 20-60% of population activity), bank vole Myodes glareolus (75-95% vs 5-25%) and common shrew Sorex arenaeus (40-90% vs 10-60%). The difference between activity in the margin and field was greater during winter than summer. Seeded margins showed a rapid increase in activity over four years for wood mouse (year 1: 15-16 trapped; year 4: 28-30), bank vole (year 1: 2-8; year 4: 16-36) and common shrew (year 1: 6-7; year 4: 18-19). Two to four new field margins were sampled within organic and conventional fields at two farms, in Essex and Leicestershire. Mark-recapture programmes were undertaken using Longworth traps over 10 nights each season from 1992 to 1998. Traps were set at 0, 1, 2, 3, 4, 5, 10, 20, 40 m into the field, replicated five times at each site. Additional, ‘one-off’ trapping sessions were undertaken over one year at five pairs of organic/conventional farms.

10 

A replicated study in 1996 in the Netherlands (Canters & Tamis 1999) found that different arthropod populations responded differently to mowing. After mowing, populations of bugs (Heteroptera), aphids (Aphidoidea), parasitic wasps (Ichneumonidae), hoverflies (Syrphidae) and rove beetles (Staphylinidae) increased to between >1.5 and nearly 2.5 times their population size prior to mowing. Mowing had the opposite effect on populations of spiders (Araneae), harvestmen (Opiliones), and moths and butterflies (Lepidoptera), reducing these populations by half or more. Ten grass margins (3 m x 900 m) on five farms were sown with grasses, including giant fescue Festuca gigantea, timothy Phleum pratense and cocksfoot Dactylis glomerata. Grassy margins were mown on approximately half of the farms at the beginning of July. Arthropods were sampled using two pyramid traps/margin installed for a three-week period five times during the 1996 growing season.

11 

A 1999 review of research into field margins in northwest Europe (de Snoo & Chaney 1999) found that biodiversity was enhanced by establishing grass margins. Three studies found that establishing grass margins increased beneficial predatory invertebrates. Another study found no increase in invertebrate predators, but a higher abundance of field mice Apodemus spp., skylark Alauda arvensis, meadow pipit Anthus pratensis, blue-headed wagtail Motacilla flava flava and linnet Carduelis cannabina in grass margins compared to normal crop edges, particularly when the grass was tall. However, one study in the Netherlands reported that in the short-term most newly created grass margins are less species rich than existing verges.

12 

A randomized, replicated controlled trial between 1993 to 1996 in Bristol, UK (Thomas & Marshall 1999) found that 4 m-wide field margins sown with rye grass Lolium perenne did not have more suction-sampled invertebrates, over-wintering invertebrates in the soil or ground beetles (Carabidae) than control cropped margins. There were 110-130 invertebrates/sample on control (cropped) and grass-sown plots. There was no difference in the number of ground beetle species (average of 8 species/plot), nor in the numbers of the four most commonly caught ground beetle species, between margin types. Wolf spiders (Lycosidae) were more abundant on grass and wildflower-sown margins than on control or naturally regenerated margins (numbers not given). Three field margins were established in spring 1993. Experimental plots 10 x 4 m were either sown with arable crop (control), rye grass or a wildflower and grass seed mix, or left to naturally regenerate. There were three replicate plots in each margin. All plots were cut annually after harvest, and cuttings left in place. Ground beetles were sampled in eight pitfall traps in or near each margin, for one week in June for four years, 1993-1996. Invertebrates were sampled using a vacuum sampler on plots of two of the three margins in June 1994. Arthropods were extracted from soil samples taken from plots of one margin in December 1993 and February 1994.

13 

A 2000 literature review (Aebischer et al. 2000) found that the UK population of cirl buntings Emberiza cirlus increased from 118-132 pairs in 1989 to 453 pairs in 1998 following a series of agri-environment schemes designed to provide overwinter stubbles, grass margins, and beneficially managed hedges and set-aside. Numbers on fields under the specific agri-environment scheme increased by 70%, compared with a 2% increase elsewhere.

14 

A 2000 literature review (Holland & Luff 2000) looked at which agricultural practices can be altered to benefit ground beetles (Carabidae). It found four European studies demonstrating that ground beetles use grassy strips (including one experimental study (Thomas & Marshall 1999)). The other three studies considered habitat use, rather than directly testing the intervention.

15 

A small, controlled study in 1999 in North Yorkshire, UK (Telfer et al. 2000) found no significant difference in numbers of ground beetles (Carabidae) in 3 m and 6 m sown grass margins and cropped edges (numbers are not presented). Five margins 3 m-wide, four 6 m-wide and four cropped field edges were sampled on one arable farm. A line of eight pitfall traps, 5 m apart, were placed 1.5 m from the hedge base in each margin. Traps were set for 29 days in April-May and seven days in September 1999. This study was carried out at the same experimental site as Carvell et al. 2004, Shore et al. 2005.

16 

A site comparison study in 1996 in Wiltshire, UK (Moonen & Marshall 2001) found that coppiced and gapped-up hedges (hedges cut to the ground and gaps planted with hedging plants) had higher plant diversity than those with adjacent sown grass and grass/wildflower strips. Hedges with adjacent sown strips had a lower abundance of pernicious weed species. Sixty hedgerows on two neighbouring arable farms were studied. All 23 sampled hedges on Noland’s Farm were trimmed annually and had the vegetation at the hedge base cut. The 37 sampled hedges on Manor Farm were trimmed in alternate years, and nine were coppiced and gapped-up. Hedge vegetation was assessed in 25 m long plots in the middle of a field edge, on both sides of each hedge, in June 1996.

17 

A 2001 paired site comparison study in south Devon (Peach et al. 2001) found that fields with 6 m grass margins were associated with increases in cirl bunting Emberiza cirlus numbers. Six of seven Countryside Stewardship Scheme plots that had 6 m grass margins and were within 2.5 km of former cirl bunting territories gained birds, whereas there were declines of 20% in cirl bunting numbers on land not-participating within the Countryside Stewardship Scheme. Forty-one 2 x 2 km² squares containing both land within the Countryside Stewardship Scheme and non-Countryside Stewardship Scheme land were surveyed in 1992, 1998 and 1999. Each tetrad was surveyed at least twice each year, the first time during mid-April to late May and the second time between early June and the end of August.

18 

A replicated, controlled study in winter 1999-2000 and summer 2000 in the West Midlands, UK (Buckingham et al. 2002) found 16 times higher winter densities of seed-eating birds (larks Alaudidae, finches Fringillidae, buntings Emberizidae and sparrows Passeridae) within 6 m of boundaries of fields with Countryside Stewardship Scheme grass margins than on fields without (1.1 vs 0.1 birds/ha). Twice as many blackbirds Turdus merula were found near the boundaries of fields without CSS grass margins than those with grass margins (1.8 vs 0.9 birds/ha). A total of 388 grass fields on 23 pastoral farms were surveyed four times each in winter and in summer. No statistical analysis was performed.

19 

A 2002 review (Evans et al. 2002) of two reports (Wilson et al. 2000, ADAS 2001) evaluating the effects of the Pilot Arable Stewardship Scheme in two regions (East Anglia and the West Midlands) from 1998 to 2001 found that grass margins benefited plants, bumblebees Bombus spp., true bugs (Hemiptera) and sawflies (Symphyta), but not ground beetles (Carabidae). The grass margins set of options included sown grass margins, naturally regenerated margins, beetle banks and uncropped cultivated wildlife strips. The review does not distinguish between these, although the beneficial effects were particularly pronounced on sown or naturally regenerated grassy margins for true bugs. The effects of the pilot scheme on plants, invertebrates (bumblebees, true bugs, ground beetles, sawflies) were monitored over three years, relative to control areas. Grass margins were implemented on total areas of 361 and 294 ha in East Anglia and West Midlands respectively.

Additional references:

Wilson S., Baylis M., Sherrott A. & Howe G. (2000) Arable Stewardship Project Officer Review. F. a. R. C. Agency report.

ADAS (2001) Ecological evaluation of the Arable Stewardship Pilot Scheme, 1998-2000. ADAS report.

20 

A replicated, controlled study during the summer of 2000 in North Yorkshire, UK (Meek et al. 2002) found grass margins contained more plant species than cropped margins but fewer species than margins sown with a grass and wildflower mix. Bumblebee Bombus spp. abundance and butterfly (Lepidoptera) diversity did not differ between treatments. However there were more meadow brown butterflies Maniola jurtina in grass margins and grass and wildflower margins than in naturally regenerated or control cropped margins. Spring numbers of ground beetles (Carabidae) and ground-dwelling spiders (Araneae) were higher in all treatments compared with the crop. Harvestmen (Opiliones) preferred grass margins to the crop in autumn. Four margins of winter cereal fields, all adjacent to hedges, on two farms, were split into 72 m long plots and sown in September 1999 with a grass mix, grass and wildflower mix, cereal crop or left to regenerate naturally. Ground and canopy-dwelling invertebrates, butterflies and plants were surveyed from late April to late September 2000 using pitfall traps, sweep netting, transects and quadrats.

21 

A controlled study from 1995 to 1997 and 1999 in Oxfordshire, UK (Perkins et al. 2002) found that yellowhammers Emberiza citrinella spent significantly more time foraging in grass margins and field boundaries than other habitats. A significantly greater number of foraging visits per unit area of available habitat were made to grass margins and field boundaries than to all other habitat types. There was no significant difference between use of grass margins and field boundary habitats or between cut and uncut grass margins. However, greater use was made of both cut and uncut grass margins combined than field boundaries. Total area surveyed was 142.8 ha in 1995-1997 and 107.0 ha in 1999. Five habitat types were studied on one mixed arable and pastoral farm: cut or uncut grass margins (2 or 10 m wide, at edge of arable field), field boundaries, arable fields (winter-sown cereals) and grass fields (pasture, silage and hay).

22 

A replicated trial in 2001-2002 in the UK (May & Nowakowski 2003) found that margins of sugar beet Beta vulgaris fields sown with grasses had fewer plant species, and slightly fewer invertebrates (individuals or species) than margins sown with wildflowers, or left to regenerate naturally. Grass-sown margins had 15 plant species/m, compared to 35 and 17 plant species/m for wildflower and naturally regenerated margins respectively, and 6-11 species/m for barley Hordeum vulgare or beet margins. The difference in invertebrate numbers between different treatments was fairly small (over 900 to over 1,700 individuals, 35-45 groups caught). In autumn 2001, 50 x 6 m margins at the edges of beet fields were sown with either sugar beet, spring barley, grasses (eight species), wildflowers (20% of seeds by weight, from 20 species) or allowed to naturally regenerate. There were two replicates of each treatment at each of three sites. In summer 2002, plants (including crop plants) were counted in the margins, and invertebrates sampled using pitfall traps, set for two weeks.

23 

A replicated trial in Wiltshire, UK from 1998 to 2000 (Asteraki et al. 2004) found that sown grassy field margins suppressed undesirable weed species, but did not enhance the abundance of invertebrates, relative to naturally regenerated uncultivated margins. Sown plots had significantly lower cover of undesirable weeds (nettle Urtica dioica, creeping thistle Cirsium arvense and black grass Alopecurus myosuroides) than naturally regenerated plots. There was no difference in the total abundance of invertebrates between field margin treatments. In 2000, there were more predatory beetles (Coleoptera) in naturally regenerated plots than in sown plots. Thirty-eight 100 x 2 m field margin plots were sown with a grass seed mix consisting of either three grass species (12 plots), six grass species (13 plots) or six grass and four wildflower species (13 plots) in autumn 1998. Eleven plots were left to regenerate naturally. The plots surrounded four fields under a Countryside Stewardship Agreement on the Harnhill Manor Farm, Wiltshire, UK. Invertebrates were sampled using pitfall traps (five traps/plot) in spring and autumn and suction traps in summer. Plants were recorded in four 1 m2 quadrats/plot in summer.

24 

A replicated controlled study in 1988-1997 in south-central Sweden (Bokenstrand et al. 2004), found that experimental plots sown with a clover Trifolium spp. and grass mix in a re-established field boundary on an organic farm had lower plant species richness than plots planted with rose bushes Rosa canina and/or sown with meadow plants or allowed to regenerate naturally one year after establishment. In two other (widened) field boundaries in a conventional system, clover and grass plots had fewer plant species nine years after establishment than plots with meadow plants. Seven years after establishment, total weed cover at the organic farm was higher in plots sown with a clover and grass mix, in natural regeneration plots and in reference boundary sections compared with plots with rose bushes and/or meadow plants. In two field boundaries total weed cover decreased in all treatments, except the clover and grass mix where it remained stable or increased. Four replicates of three or four treatments were established in experimental plots at the site of each field boundary in 1988 or 1990, either by widening an existing boundary or re-establishing a previously removed dirt road (organic site). All plots were cut annually in late summer and the cuttings removed. Vegetation surveys were carried out twice in experimental plots (1991-1993 and 1997) and once in reference boundaries (1997) in three to five 0.25 m2 quadrats. It is not clear whether the results for clover and grass plots were a direct result of planting nectar flowers or grass.

25 

A replicated controlled trial in 2000-2002 in North Yorkshire (Carvell et al. 2004) found 6 m-wide field margin plots sown with a ‘tussocky grass’ seed mix supported no more bumblebees Bombus spp. than conventionally cropped field margins. The study was carried out on three arable field margins of one farm. Each margin was split into five 72 m x 6 m plots and each plot subjected to one of five treatments: naturally regenerated, sown tussocky grass mix, sown grass and wildflower mix, split treatment of 3 m tussocky grass and 3 m grass and wildflower mix, or cropped to the edge. Bumblebee activity was surveyed using a standard ‘bee walk’ methodology. This study was carried out at the same experimental site as Telfer et al. 2000, Shore et al. 2005.

26 

A replicated study in the summers of 1999-2000 in the UK (Critchley et al. 2004) found that sown grass margins had fewer plant species than six other conservation measures, including naturally regenerated margins. Sown grass margins were not considered one of the best options for conservation of annual herbaceous plant communities. Average numbers of plant species in the different conservation habitats were sown grass margins 4.4, wildlife seed mixtures 6.7, uncropped cultivated margins 6.3, undersown cereals 5.9, naturally regenerated margins 5.5, no-fertilizer conservation headlands 4.8, spring fallows 4.5, overwinter stubbles 4.2, conservation headlands 3.5, grass leys 3.1. Plants were surveyed on a total of 294 conservation measure sites (each a single field, block of field or field margin strip), on 37 farms in East Anglia (dominated by arable farming) and 38 farms in the West Midlands (dominated by more mixed farming). The ten habitats were created according to agri-environment scheme guidelines. Vegetation was surveyed once in each site in June-August in 1999 or 2000. The vegetation was examined in thirty 0.25 m2 quadrats randomly placed in 50-100 m randomly located sampling zones in each habitat site. All vascular plant species rooted in each quadrat as well as bare ground or litter were recorded.

27 

A replicated study in 2000 and 2002 in Dorset, UK (Powell et al. 2004) found that field margins dominated by grass species supported different invertebrate communities in the adjacent crop to margins dominated by wildflower species. In 2000, margins dominated by grass species were associated with ground beetles (Carabidae); Bembidion spp. and Carabus spp., as well as rove beetles (Staphylinidae); Tachinus spp.. Margins dominated by wildflowers were associated with ladybirds (Coccinellidae) and weevils (Curculionidae). In 2002, grassy margins were associated with ground beetles, Bembidion spp. and click beetles (Elateridae). Thirty field boundary lengths from six study fields on one farm were assessed for plant species cover. Invertebrates were sampled in eight pitfall traps adjacent to the field boundary.

28 

A replicated, controlled study in 1997-2000 in Essex, UK (Field et al. 2005) found that total butterfly (Lepidoptera) abundance, but not species richness, was higher in 6 m-wide grass margins (average 45.8 butterflies/km/visit) (study did not distinguish between sown and naturally regenerated grass margins) than in control cropped sections (average 20.9). Of the ‘key’ grassland butterfly species, only the meadow brown Maniola jurtina had greater abundance in grass margins (average 18.9 butterflies/km/visit) than in controls (average 8.9). Significantly more butterflies, including M. jurtina, were found in a sown grass margin established adjacent to a permanent set-aside field than on all other margin types. Sown grass margins (not adjacent to permanent set-aside fields) had the lowest abundance of gatekeeper Pyronia tithonus, skipper Thymelicus spp. and large skipper Ochlodes venata butterflies. Five grass margins were established on two farms according to the requirements of the Countryside Stewardship Scheme in 1996 and sown with grass seed mixtures (6 or 9 species). In addition, three margins were established by natural regeneration on one farm, and on both farms one arable field edge without margins was used as a control. Butterfly abundance was monitored weekly along transects from late June to early August 1997-2000. All butterflies were recorded, but special note was taken of ‘key’ grassland species: meadow brown, gatekeeper, small skipper Thymelicus sylvestris, Essex skipper T. lineola, and large skipper. This study is part of the same experimental set-up as Field & Mason 2005, Field et al. 2006, Field et al. 2007a, Field et al. 2007b.

29 

A replicated, controlled study in 1997-2000 in Essex, UK (Field & Mason 2005) found that numbers of the gatekeeper butterfly Pyronia tithonus increased in sown grass margins one year after establishment and were significantly higher in 2000 than in 1997. Although more gatekeepers were recorded in grass margins than in control sites (without margins) during most visits (except for one farm in 1998), abundance was significantly higher at only one farm. More gatekeepers were observed on grass margins with adjacent hedgerows and on control sites with hedgerows than on the grass margins without hedgerows. Grass margins (2 m wide, 141-762 m long) were established in October 1996-2000 by sowing three different grass seed mixtures (eight margins: 4-5 species, mainly Dactylis glomerata; one margin: 6 spp., mainly Festuca rubra). Three field edges without margins (one on each of three farms, 133-343 m long, 100-300 m hedgerow) were used as controls. Gatekeeper abundance was monitored weekly along transects in July and August. This study is part of the same experimental set-up as Field et al. 2005, Field et al. 2006, Field et al. 2007a, Field et al. 2007b.

30 

A small-scale controlled study in 2000-2001 in Essex, UK (Gardiner & Hill 2005) found densities of lesser marsh grasshoppers Chorthippus albomarginatus (69% of all grasshoppers found) and meadow grasshoppers C. parallelus (31% of all grasshoppers found) in two Countryside Stewardship Scheme field margins (one margin naturally regenerated, one margin created from existing grass ley) were not statistically different than in intensively managed habitats (arable field, heavily grazed cattle and sheep pastures). Adult density of both grasshopper species was higher on lightly grazed pasture and a disused farm track than in either field margin. Grasshopper density was initially higher in the sown grass margin than the naturally regenerated margin or control grazed pasture three years after establishment (0.4, 0.1 and 0.3 grasshoppers/m2 respectively). Seven years into the 10-year agreement, grasshopper density had decreased in the sown and naturally regenerated margins (0.05 grasshoppers/m2) but increased substantially in the control grazed pasture (1.2 grasshoppers/m2). The authors suggested that annual cutting for hay was the reason for the reduced grasshopper populations in the margins. In each of nine study sites (two field margins, one arable field, one lightly grazed pasture, one heavily grazed cattle pasture, one heavily grazed sheep pasture, one hay meadow, one set-aside grassland, one disused farm track), 10 quadrats (2 x 2 m2) were randomly positioned in a 100m2 plot. Grasshoppers were counted in quadrats once in July and once in August (2000 and 2001).

31 

A replicated study in winter 2002 in Oxfordshire, UK (Pywell et al. 2005) found that the total abundance, species richness and diversity of beetles (Coleoptera) and spiders (Araneae), as well as abundance and species richness of rove beetles (Staphylinidae) were lower in field margins than in hedge bases, but there was no difference between recently sown (3-4 years old) and mature field margins (about 50 years old). The important aphid predator Bembidion lampros (ground beetle Carabidae) occurred in higher densities in both recently sown grass margins (8 individuals/m2) and mature (40-60 years old) hedge bases (12/m2) compared with mature field margins and recently planted hedges (2-5 years old). Another important aphid predator the rove beetle Tachyporus hypnorum was also found at highest densities in recently sown grass margins, although this finding was non-significant. Recently sown grass margins had higher grass cover, but lower grass species abundance and vascular plant species diversity than in the other habitats. Recently sown grass margins also had lower vascular plant species richness and lower wildflower and moss cover than mature field margins. Four overwintering habitats for beetles and spiders were surveyed at one site: recently sown grass margin, mature field margin, recently planted hedge base and mature hedge base. Five geographically separate replicates of each of the four habitats were sampled for beetles and spiders in February 2002 by taking 12 soil core samples in a 70 m long sampling section. Percentage cover of vascular plant species, moss and bare ground was estimated, and biomass (dry matter) and organic carbon content were measured.

32 

A replicated, controlled trial in North Yorkshire, UK (Shore et al. 2005) found more bank voles Clethrionomys glareolus and common shrews Sorex araneus on sown grass field margins in autumn than on control cropped margins, but no such differences in spring. There were 13-14 and 26-38 bank voles/autumn trapping period on 3 m and 6 m margins respectively, compared to 0-1 voles on control margins. There were 14-15 and 10-13 common shrews/autumn trapping period on 3 m and 6 m margins respectively, compared to 1-4 common shrews on control margins. Wood mice Apodemus sylvaticus were found in similar numbers on all margin types in autumn and spring (0-29 mice/trapping period). Four 3 m-wide and four 6 m-wide field margins were established in autumn 1997 and sown with a mix of grasses on one arable farm. Small mammals were trapped in spring (April-May) and autumn (September-October) 1999 and 2000 on sown field margins and four conventional cropped field edges (controls). On four separate nights in each trapping period, twenty Longworth traps were set 10 m apart on each margin, 10 along the edge furthest from the crop, and 10 placed 2 m into the crop. This study was carried out at the same experimental site as Telfer et al. 2000, Carvell et al. 2004.

33 

A replicated study in June and September 2002 in Yorkshire, UK (Woodcock et al. 2005) found that beetle (Coleoptera) abundance and species richness on experimental plots was strongly influenced by the type of seed mixture. A mix containing only grass species (‘Countryside Stewardship Scheme mix’) had a higher abundance and species richness of beetles than a mix containing mainly flowering plants and no tussock grass species (‘fine grass and forbs mix’). A third mix containing wildflowers, fine and tussock grass species (‘tussock grass and forbs mix’) had similarly high beetle numbers and richness to the grass-only Countryside Stewardship Scheme mix. Beetle diversity (Shannon-Weiner index) did not differ between the different seed mixes. The plant communities in the grass-only and tussock grass and forbs mixes were more similar to each other than to the fine grass and forbs mix. Each of the seed mixtures was randomly sown on three of nine experimental plots in each of five blocks on one farm in autumn 2001. Plots measured 25 x 5 m. Seed mixes contained 3-7 grass and 0-19 forb species. The strips were cut once in July with cuttings left in place. Plant diversity and cover and vegetation structure were surveyed in June and September 2002 using 0.5 x 0.5 m quadrats and a ‘drop disk’. Beetles were sampled using a Vortis© (Burkland Ltd., UK) suction sampler. Five samples (15 suctions for 10 seconds) were taken in each plot (total area sampled 1.32 m2) on each visit. This study was extended in Woodcock et al. 2008.

34 

A replicated study in 2005 in the Netherlands (Alebeek et al. 2006) found no clear effects of sown field margins and flower strips on invertebrate pest populations. No figures were presented. A total of 15 km of perennial field margins and flower strips were sown along field edges and across fields in a 400 ha area on five arable fields. Flower availability, natural enemy and key pest densities were measured in 2005.

35 

A replicated, controlled study in summer 2004 in lowland England (Critchley et al. 2006) found sown margins contained more species of grasses and wildflowers (including perennials) as well as more foodplants for birds, butterfly (Lepidoptera) larvae and bumblebees Bombus spp. foodplants than cereal field headlands. Margins sown with a mixture of grasses and wildflowers had fewer weed species than unsown sites and compared to grass-only sown margins they had a greater number of plant species and up to 60% more perennial wildflowers. Annual plants were more prevalent in grass-sown margins up to two years old, but species composition was not related to age in older margins. One hundred and sixteen margins were studied in eight regions. Five types of margin (minimum length 120 m) were monitored: sown with grass mix (less than two years old), sown with grass mix (more than two years old), sown with grass and wildflower mix, naturally regenerated and normal cereal field margins (control). This study was part of the same experimental set-up as Critchley et al. (2007).

36 

A replicated, controlled study in 1997-2000 in Essex, UK (Field et al. 2006) found significantly greater butterfly (Lepidoptera) species richness on 2 m sown grass margins, but not on 6 m (study does not distinguish sown from naturally regenerated 6 m margins) grass margins compared to control sites (field edges without grass margins). Butterfly species richness was also higher on 2 m grass margins sown with a more diverse seed mixture. Significantly higher butterfly diversity was found on 2 m grass-sown margins adjacent to hedgerows than on those without hedgerows. No significant differences were found in butterfly species richness between 6 m margins and controls. Plant species richness was higher on both 2 and 6 m margins running alongside hedgerows than on those without hedgerows. The 6 m margins established by natural regeneration held the highest plant species richness. Twenty-six margins were established on three farms in October 1996-1998: grass-sown (2 m-wide), grass-sown (6 m-wide), naturally regenerated (6 m-wide), control crop (2 and 6 m-wide). Grass sown margins were established using a range of grass seed mixtures containing common grass species. All plant species in the margins and adjacent hedgerows were recorded in July-August 1998-2000 and abundance measured using the DAFOR scale. Butterflies in margins and control sites were monitored weekly along transects between 1997 and 2000 in suitable weather. This study is part of the same experimental set-up as Field et al. 2005, Field & Mason 2005, Field et al. 2007a, Field et al. 2007b.

37 

A replicated paired site-comparison study in 2006 in the UK (Kleijn et al. 2006) found that installing 6 m-wide grass field margin strips along arable fields had no effect on the number of birds or bird species found to breed or forage on farmland. Under the Countryside Stewardship Scheme, these 6 m-wide grass field margin strips were either created through natural regeneration, sowing grass species, or sowing a grass/wildflower mixture. The study surveyed seven pairs of fields (one with field margins managed under the Countryside Stewardship Scheme, one conventionally farmed) and the 12.5 ha area surrounding each field, from each of three different parts of the UK four times during the breeding season.

38 

A replicated, paired-sites comparison in mid-summer 2003 in southern England (Marshall et al. 2006) found that plants, bees (Apidae) and grasshoppers (Orthoptera) were all more abundant or had higher diversity on fields with 6 m-wide sown grassy margins, compared to control fields without margins. For example, an average of 5.2 grasshopper and cricket individuals and 1.8 species were found in fields with grass margins, compared to 0.9 individuals and 0.6 species in control fields without grass margins. However spiders (Araneae), ground beetles (Carabidae) and farmland birds did not respond positively to grass margins, with 11-18 bird species/site for fields with grass margins, compared to 11-15 species/site for fields without margins. Forty-two arable field sites in 21 pairs of fields with and without grass margins were studied. Vegetation was assessed in 1 x 5 m quadrats and plant cover assessed visually. Numbers of nesting birds were assessed using territory mapping. Bees were surveyed from June to mid-July using butterfly and sweep nets along a transect for 15 minutes. Spiders were sampled in pitfall traps in the crop and margin. Grasshopper numbers and activity were measured through sweep netting and visual/audial assessment.

39 

A replicated, controlled study in 2001-2005 on ten farms in England (Ogilvy et al. 2006) found that of three margin types, birds favoured margins sown with a tussock grass and wildflower mix in 2003 and a fine grass and wildflower mix in 2004 to margins sown with grass species only. Flower abundance and species richness was highest in margins sown with a fine grass and wildflower mix and lowest in the standard grass mix margins. Bumblebee Bombus spp. abundance and species richness were highest on the tussock grass and wildflower mix and lowest on the standard grass margin mix. More birds were associated with scarified than cut grass margins in July 2004. Scarified margins had greater plant diversity and more unsown plant species. Cutting maintained plant species diversity in the grass and wildflower mixes. Grass-specific herbicide application benefited fine grass and flower species. The effects of management treatments on invertebrate abundance were habitat and group specific. Scarified margins had greater beetle (Coleoptera) and true bug (Hemiptera) diversity at some sites. Cutting and grass-specific herbicide application in both tussock grass and fine grass wildflower mixes increased abundance of true bugs and planthoppers (Fulgoroidea). Butterfly (Lepidoptera) diversity in the standard grass margins was enhanced by scarification, and increased in the tussock grass and wildflower mix through grass-specific herbicide application. In autumn 2001, three grass mixes (standard Countryside Stewardship Scheme mix, tussock grass and wildflower mix, fine-leaved grass and wildflower mix) were sown in 6 m-wide margins at three sites, with five replicates. From 2003 each margin type was subjected to three different management treatments: cutting, scarification or selective grass-specific herbicide application.

40 

A replicated, controlled trial in 2004 in thirty-two 10 km grid squares across England (Pywell et al. 2006) found that 6 m-wide sown grass margins had more bumblebee Bombus spp. species, and a higher abundance of foraging bumblebees, than conventionally cultivated and cropped field margins (on average 6-8 bumblebees of 1.3-1.4 species/transect on grassy margins, compared to 0.2 bumblebees of 0.1 species/transect for cropped margins). Older grassy margins, sown more than three years previously, did not attract more foraging bumblebees than those sown in the previous two years. Field margins were 6 m-wide and part of agri-environment scheme agreements. Five field margin types were investigated: grass mix (sown between 1993 and 2000), grass mix (sown between 2002 and 2003), grass and wildflower mix (sown between 1999 and 2003), ‘pollen and nectar’-rich margin (sown between 2002 and 2003), control cropped margins. Grass mixes typically included species such as cocksfoot Dactylis glomerata and timothy Phleum pretense. All five margin types were surveyed within each 10 km grid square (excluding the grass and wildflower mix which was not present in all squares), giving a total of 151 margins. Bumblebees were counted on a 100 x 6 m transect in each field margin, once in July and once in August.

41 

A replicated study in 2003-2004 in Devon, UK (Smith 2006) found that the density of the meadow grasshopper Chorthippus parallelus was significantly higher in 6 m-margins than 2 m-wide margins (study does not distinguish between sown and naturally regenerated margins), grazed pasture or long-term set-aside. Two-metre-wide margins supported higher meadow grasshopper densities than intensively grazed pastures, but Countryside Stewardship Scheme P1 pastures (lightly grazed). Within the 6 m-margins, grasshoppers were more abundant on the outer edge (adjacent to the crop) than on the inner edge (adjacent to a hedge). Meadow grasshoppers were found at highest densities in swards measuring between 30 and 50 cm tall. At low abundances, dock species Rumex spp. and cocksfoot Dactylis glomerata had a positive impact on meadow grasshopper density, but a negative impact at high abundances. Meadow grasshopper density was negatively impacted by bare ground and rye grasses Lolium spp. Fifteen farms were surveyed, 12 were subject to a Countryside Stewardship Scheme prescription and of the Countryside Stewardship Scheme farms, three were organic production systems. Five habitat types were surveyed: intensive dairy pasture, long-term set-aside, Countryside Stewardship Scheme P1 grazed pasture, Countryside Stewardship Scheme 2 m-wide field margin, Countryside Stewardship Scheme 6 m-wide field margin. Forty-one arable field margins were studied. Thirty-six of the margins were established through sowing (study does not specify seed mixture), the remaining five were naturally regenerated. Margins were all cut, but at different frequencies and to different extents in July-August. Grasshoppers were surveyed between July and September in 2003, and July-August in 2004. Two sample blocks (2 x 30 m) were set up in long-term set-aside, grazed pasture and intensive dairy pasture, one at the field edge and one 30 m from the field edge. In fields with margins, one sample block (2 x 30 m for 2 m margins; 6 x 30 m for 6 m margins) was established at the field edge. Grasshoppers were sampled in 0.5 m2 box quadrats. Vegetation height and cover were measured in five 0.5 m2 quadrats.

42 

A replicated study in 1999 and 2003 in East Anglia and the West Midlands, England (Stevens & Bradbury 2006) found that a combination of creating uncultivated and planted margins around fields was strongly positively associated with four out of twelve farmland bird species analysed. These were skylark Alauda arvensis (a field-nesting species) and chaffinch Fringilla coelebs, whitethroat Sylvia communis and yellowhammer Emberiza citrinella (all boundary-nesting species). The study did not distinguish between uncultivated and planted margins. The study was carried out on 256 arable and pastoral fields on 84 farms.

43 

A replicated study in 2003 and 2004 in England (Askew et al. 2007) found that sown grass field margins tended to have higher numbers of small mammals than set-aside. Numbers of captured small mammals were highest in 2 m margins (2.9-4.4 individuals), followed by 6 m margins (2.5-3.6) and set-aside (1.6-2.0). Numbers of small mammals captured were correlated with sward height in 2 m margins. In 2003, significantly more common shrews Sorex arenaeus were captured in 2 m margins (1.4 individuals) than set-aside (0.6) and more wood mice Apodemus sylvaticus were found in 6 m margins (1.1) than set-aside (0.5). The trend was similar for bank voles Clethrionomys glareolus in 2004: 6 m margins (1.6), 2 m margins (1.4) and set-aside (0.5). Species richness did not differ significantly (1.7-2.0). Species richness, total number of small mammals captured, and the number of bank voles and common shrews captured was higher in 6 m margins cut every 2-3 years compared to those cut annually, although this was only significant for common shrews in 2003. Following establishment, 2 m margins were cut at 2-3 year intervals. For 6 m margins, eight 2 m strips at the edges of margins were cut annually and 12 were cut every 2-3 years. Twelve small mammal traps were set within 20 plots per treatment (1 m from the habitat boundary) for four days in November-December 2003-2004. Mammals were individually fur-clipped and released.

44 

A replicated site comparison study in the UK (Critchley et al. 2007) found that sown grassy margins more than two years old had 87-95% cover with grasses. Those sown with wildflowers had on average 28% cover with non-grass broadleaved plants, compared to 14% cover in margins sown with a simple grass seed mix. This option was not considered the best option for conservation of arable plants. A total of 75 sown grass margins were surveyed in 2004. Twenty-two of them were sown with some non-grass flowering species, as well as grasses. Margins were randomly selected from eight UK regions. Plants were surveyed in thirty 0.025 m2 quadrats within a 100 m sampling zone of each margin and percentage cover across all quadrats estimated. This study was part of the same experimental set-up as (Critchley et al. 2006).

45 

A replicated, controlled study in 1997-2000 in Essex, UK (Field et al. 2007a) found that total butterfly (Lepidoptera) abundance was higher in grass margins (average 66.6 butterflies) than in control sections (field edges without margins) (average 25.6). Of the ‘key’ grassland butterfly species, both meadow brown Maniola jurtina and skipper butterflies Thymelicus spp. had higher abundance in sown grass margins (average 15.5 and 13.9 individuals respectively) than in controls (average 3.6 and 1.2 respectively). Between 1997 and 2000 there was a significant reduction in the abundance of total butterflies (from an average of 100.6 to 47.0), Thymelicus spp. (from 32.4 to 3.9) and large skipper Ochlodes venata (from 15.3 to 0.6) in the margins. During the same time, the average abundance of gatekeeper Pyronia tithonus increased from 2.2 to 12.9 in the margins. Grass margins were established as described in (Field & Mason 2005). Butterfly abundance was monitored weekly along transects from late June to early August 1997-2000. All butterflies were recorded, but special note was taken of ‘key’ grassland species: meadow brown, gatekeeper, small skipper Thymelicus sylvestris, Essex skipper T. lineola, large skipper. This study is part of the same experimental set-up as Field et al. 2005, Field & Mason 2005, Field et al. 2006, Field et al. 2007b.

46 

A replicated, controlled study in the summers of 1997-2000 and 2003 in Essex, UK (Field et al. 2007b) found that butterfly (Lepidoptera) abundance was higher in 2 m and 6 m-wide Countryside Stewardship Scheme margins than in control margins (field edges without established grass margins). Comparisons between grass-sown 2 m-margins and control sections showed 64 vs 24 butterflies/km/visit and 54 vs 19 for 6 m-margins (study does not distinguish between the effects of sown and naturally regenerated 6 m-margins). The meadow brown butterfly Maniola jurtina also occurred in higher numbers in Countryside Stewardship Scheme field margins, 2 m-margins and their control sections had 15 vs 4 individuals/km/visit, 6 m-margins had 22 vs 5/km/visit. Butterfly abundance and species richness did not change over the study period in either 2 or 6 m-margins or in a transect across farmland. Plant species richness declined significantly within sown field margins of both widths from 1998 to 2003 as the sown grass species became dominant. Sown 6 m-margins had lower plant species richness in 2003 (20 species) compared with naturally regenerated 6 m-margins (35 species). Eleven margins were studied on three farms. Two metre-margins were sown with a grass-only seed mixture and the vegetation left uncut after the first year. Six metre-margins were established through natural regeneration or by sowing, all cut annually after 15 July. This study was part of the same experimental set-up as Field et al. 2005, Field & Mason 2005, Field et al. 2006, Field et al. 2007a.

47 

A randomized, replicated, controlled trial from 2002 to 2006 in eastern England (Henderson et al. 2007) (same study as Pywell et al. 2007, Ramsay et al. 2007) found that the management of sown grass field margins affected bird use more than the seed mix used. Bird densities were higher on disturbed and grass-specific herbicide-treated plots than on cut plots (no actual bird densities given, only model results). Bird densities were linked to densities of diurnal ground beetles (Carabidae), especially in disturbed and grass-specific herbicide-treated plots. The number of birds using the margins in summer increased by 29% between 2003 and 2006. In winter, there were twice as many birds on cut margins than uncut margins, and twice as many birds in the second year than the first. Field margin plots (6 x 30 m) were established using one of three seed mixes: Countryside Stewardship mix (seven grass species), tussock grass mix and a mixture of grasses and wildflowers designed for pollinating insects. The margins were managed in spring from 2003 to 2005 with one of three treatments: cut to 15 cm, soil disturbed by scarification until 60% of the area was bare ground, treated with grass-specific herbicide at half the recommended rate. There were five replicates of each treatment combination, at two farms. Birds were surveyed five to eight times between April and July from 2002 to 2006. In the winters of 2004-2005 and 2005-2006, birds were surveyed on 6 m-margins on 10 farms with two seed mixes (tussocky grass and fine grass). Margins were either cut in autumn or uncut. There were four replicates of each treatment combination per farm.

48 

A 2007 literature review of the effects of agri-environment scheme options on small mammals in the UK (Macdonald et al. 2007) identified three studies that found small mammal abundance tended to be higher in grass margins compared to cropped fields (Brown 1999, Macdonald et al. 2000, Shore et al. 2005). One study (Shore et al. 2005) also found that wider grass margins had highest numbers of bank voles Myodes glareolus.

Additional references:

Macdonald, D.W., Tew, T.E., Todd, I.A., Garner, J.P. & Johnson, P.J. (2000) Arable habitat use by wood mice (Apodemus sylvaticus) 3. A farm-scale experiment on the effects of crop rotation. Journal of Zoology, 250, 313–320.

49 

A small replicated site comparison study in 2005 in Oxfordshire, UK (Marshall 2007) found that field margins sown with a grass and wild flower mix had more species and individual grasshoppers and crickets (Orthoptera) than margins sown with grass only, wildflower margins, or grassy tracks. Narrow grass and wildflower margins (2 m wide) had an average of 10 insects from four species, compared to 1-4 individuals from less than two species for the other margin types. Wide grass and wildflower margins (6 m) also had more species and individuals than others (8 individuals, 2.5 species/margin on average), but this was not always statistically significant. Seventy-three percent of all crickets and grasshoppers caught were in margins sown with a grass and flower mix. The grass and flower margins had intermediate vegetation height (30-40 cm), low cover of bare ground and intermediate grass and flower cover compared to other margins. Three replicates of five field margin types were monitored on a large mixed farm: grass and wildflower mix (2 m), grass and wildflower mix (6 m), grass only mix, wildflower mix, grassy track. Grasshoppers and crickets were surveyed using a sweep net over two 20 minute periods in a 50 m section of each margin, in late July or August 2005.

50 

A randomized, replicated, controlled trial from 2002 to 2006 in eastern England (Pywell et al. 2007) (same study as Henderson et al. 2007, Ramsay et al. 2007) found that floristically enhanced grassy margins supported more bumblebees Bombus spp. and butterflies (Lepidoptera) than grass-only margins. For bees and butterflies, there was no difference in abundance or number of species between the grass and wildflower mix and the pollinating insect mix (35-47 bumblebees of four species and 18-20 butterflies of six species/125 m2 plot on average on the grass and wildflower mix and the pollinating insect mix, compared to 10 bumblebees of two species and 12 butterflies of five species on grass-only margins). Different types of management did not affect the abundance of bees and butterflies or the number of butterfly species, but there were more bumblebee species on plots treated with grass-specific herbicide in spring (average four species/125 m2, compared to three species on cut or disturbed plots). Field margin plots (6 x 30 m) were established in 2000-2001 using one of three seed mixes: Countryside Stewardship mix (seven grass species, sown at 20 kg/ha), tussock grass mix (seven grass species, 11 wildflowers, sown at 35 kg/ha) and a mixture of grasses and wildflowers designed for pollinating insects (four grass species, 16-20 wildflowers, sown at 35 kg/ha). The margins were managed in spring from 2003 to 2005 with one of three treatments: cut to 15 cm, soil disturbed by scarification until 60% of the area was bare ground, treated with grass-specific herbicide in spring at half the recommended rate. There were five replicates of each treatment combination, at three farms.

51 

A randomized, replicated, controlled trial from 2002 to 2006 in eastern England (Ramsay et al. 2007) (same study as Henderson et al. 2007, Pywell et al. 2007) found that sown grass margins had a greater abundance of planthoppers (Auchenorrhyncha) than margins sown with a grass and wildflower mix. Grass-only margins had 30-70 planthoppers/plot on average (depending on management), while other margins had 25-45 planthoppers/plot. There were fewer planthoppers in disturbed (scarified) plots (20-30 planthoppers/plot on average, for all seed mix treatments) than in those cut or treated with grass-specific herbicide in spring (35-70 planthoppers/plot on average). Field margin plots (6 x 30 m) were established in 2000-2001 using one of three seed mixes: Countryside Stewardship mix (seven grass species, sown at 20 kg/ha), tussock grass mix (seven grass species, 11 wildflowers, sown at 35 kg/ha) and a mixture of grasses and wildflowers designed for pollinating insects (four grass species, 16-20 wildflowers, sown at 35 kg/ha). The margins were managed in spring from 2003 to 2005 with one of three treatments: cut to 15 cm, soil disturbed by scarification until 60% of the area was bare ground, treated with grass-specific herbicide in spring at half the recommended rate. There were five replicates of each treatment combination at three farms. Planthoppers were sampled in June and September 2003 and 2004 by suction sampling (seventy-five 10 second sucks/plot in total, sampled from 40.5 m2/plot).

52 

A 2007 literature review in Leicestershire, UK (Stoate & Moorcroft 2007) found that grass margins contained large numbers of overwintering invertebrates such as rove beetles (Staphylinidae) and ground beetles (Carabidae) as well as high numbers of yellowhammer Emberiza citrinella and whitethroat Sylvia communis nests; yellowhammer had higher survival than in adjacent hedgerows.

53 

A 2008 literature review of grasshoppers (Acrididae) and bush-crickets (Tettigoniidae) (order: Orthoptera) in 6 m-wide grass margins around arable fields in eastern England, UK (Gardiner et al. 2008) found that grass margins appear to increase grasshopper and bush-cricket diversity and abundance in landscapes with small to intermediate field sizes (Marshall et al. 2006), but not in landscapes with large and intensively-farmed fields (Gardiner & Hill 2005). The review suggested that landscape context at different scales, management routines such as cutting and species composition within the margins affect grasshopper/cricket populations in field margins.

54 

A replicated, controlled study in summer 2005 in south Wiltshire, UK (Holland et al. 2008) found that a higher proportion of grain aphids Sitobion avenae were parasitized in winter wheat fields with wide margins (5-6 m) compared to standard margins (<1 m) ten days after inoculation with aphids. One month after inoculation more aphids were parasitized at 20 m from the wide margin compared with the standard margins. Flying predators reduced aphid numbers by 90% and 93% in fields with standard and wide field margins respectively one month after inoculation whereas ground-dwelling predators achieved reductions of only 40% and 18%. Ground-dwelling predators had no additional effect on aphid abundance compared to when only flying predators were present in fields with either wide or standard width field margins. Spiders (Araneae) were more abundant in suction samples collected in fields with wide margins. Flying predators and balloon flies (Empididae) were more abundant in fields with standard margins. Exclusion cages were used to investigate the effect of ground-dwelling and flying predators in isolation or together on aphid abundance, as well as in the absence of predators in fields with different margin widths (standard (<1 m) or wide (5-6 m)) in ten winter wheat fields. Two transects with exclusion cages were established in each field, at 20 and 80 m from margin. Aphid abundance was monitored four days before and 10, 20 and 32 days after inoculation with aphids on 10 June.

55 

A paired, replicated, controlled study in spring 2006 in Berkshire, UK (Smith et al. 2008a) found that earthworms (Lumbricidae), woodlice (Isopoda), and rove beetles (Staphylinidae), as well as three main feeding groups (litter consumers, soil ingesters and predators) had higher abundance and species density in sown grass strips compared with the field bean crop. However the presence of grass strips did not increase soil macrofaunal diversity outside the field margin in either the adjacent crop, or under the adjacent hedgerow. The species composition of soil macrofaunal communities in grass strips was different compared with other habitats on a within-field and a within-farm scale. Six metre wide grass strips were established and managed according to the Countryside Stewardship Scheme guidelines in 2000-2001. Soil core samples were collected in April-May along transects perpendicular to paired hedgerow boundaries at 0 m (under hedge), 3 m (in grass strip/crop), and 9 and 27 m into the crop. Five other habitats were sampled for the within-farm analysis (winter wheat fields, pasture, set-aside, coniferous Pinus sylvestris plantation, and broadleaf plantation) in May.

56 

A replicated, controlled study in 2005 in Cambridgeshire, UK (Smith et al. 2008b) found that the species density and abundance of woodlice (Isopoda) and beetles (Coleoptera), as well as the species density of earthworms (Lumbricidae) was higher in sown grass margins than in the winter wheat crop. Species densities and abundances/m2 (grass margin average vs. crop average) were woodlouse density 2.8 vs 0 and woodlouse abundance 74 vs 0; beetles 17.3 vs 10.0 and 80 vs 41; earthworms 5.1 vs 3.8 and 281 vs 244; millipedes (Diplodopa) 3.2 vs 3.5 and 36 vs 38; centipedes (Chilopoda) 2.1 vs 1.8 and 14 vs 18. Scarified plots had lower abundance and fewer species of woodlice compared with spring cut and herbicide treated plots while species composition was similar to that of the crop. Scarified plots also had fewer soil-feeders and litter-feeders, and predatory species densities were lower, compared with the other plots. Field margins were created in 2001 with four replicated blocks of nine treatments (three seed mixtures x three management regimes) in one arable field. Soil macrofauna was sampled through soil cores in April and October 2005.

57 

A replicated study in summer 2002-2004 and 2006 in England (Woodcock et al. 2008) (extension of Woodcock et al. 2005) found higher abundance and species richness of predatory beetles (Coleoptera) in margins containing tussock grass species than in margins with fine grasses only (independent of the presence of wildflowers). However the abundance of herbivorous beetle species was lower in margins containing only grass species and higher in grass mixtures with a wildflower component. Soil scarification had a positive effect on species richness of predatory beetles. Three different seed mixtures were sown: grass only, tussock grass and wildflowers, fine grass and wildflowers. Each of the seed mixtures was randomly sown on three of nine experimental plots in each of five blocks on three farms in autumn 2001. Plots measured 25 x 5 m. From 2003, three different management practices were applied in each replicate block in May each year: cutting the vegetation to 10–15 cm; application of grass-specific herbicide (fuazifop-p-butyl) at 0.8 l/ha; and scarification of 60% of the soil surface. Plant diversity and cover and vegetation structure were surveyed yearly in June using 0.5 x 0.5 m quadrats and vertical drop pins. A Vortis suction sampler (75 suctions of 10 seconds each) was used over a fixed area (equivalent to 1.45 m2) in each plot on each sampling date to collect beetles. Rove beetles (Staphylinidae), ground beetles (Carabidae), ladybirds (Coccinellidae), leaf-beetles (Chrysomelidae) and weevils (Curculionoidea) were determined to species level and categorized as either herbivorous or predatory.

58 

A replicated and controlled habitat selection study in 2003-2005 in south-western Finland (Yletyinen & Norrdahl 2008) found that field voles Microtus agrestis in riparian field margins moved on average longer distances in narrow (?5 m) filter strips than in wide (>15 m) buffer zones. Home range sizes tended to be larger in narrow than in wide margins, although these differences were not significant. Field voles were most frequently found in control plots where vegetation was left uncut with no supplementary food or cover added, in both narrow and wide riparian field margins. Crop fields and all mown habitat types were used significantly less by field voles in wide buffer zones than in narrow filter strips. Overall, mown plots were used less than unmown plots. In wide buffer zones, voles used mown habitats proportionally significantly less than other available habitats, whereas in narrow filter strips there was no difference in use between mown and unmown plots. Supplementary food appeared to attract voles in unmown plots in both wide and narrow riparian field margins, but not in mown plots. Mown plots with supplementary food provided were avoided by voles in wide margins. Riparian field margin width did not affect the proportional use of crop fields and field margin habitats from late autumn to spring (summer use not tested). Field margins were created under an agri-environment scheme prior to the study. In mid-June 2005, one 210 m-long section in each of four riparian field margins was divided into fourteen 15 m-long experimental plots, half of which were mown to <20 cm. Food and/or cover was added to mown/unmown plots (total eight treatments). Trapping and radio-tracking field voles started two weeks after habitat manipulation. Radio-tracking for the seasonal habitat-use analysis was done in summer (June 2003), late autumn (December 2003), winter (January 2004) and spring (April-May 2005).

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A replicated study in May-August 2004-2006 in Aberdeenshire, Scotland (Douglas et al. 2009) found that yellowhammers Emberiza citrinella appeared to use cut field margins (sown or naturally regenerated) significantly more in late than early summer for foraging. Cut patches were used more frequently in margins with swards >60 cm tall. The authors suggest that yellowhammers used cut patches disproportionately as the uncut sections grew taller and so reduced access to invertebrates.

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A replicated, controlled trial in spring 2008 in Scotland (Lye et al. 2009) found that on farms under the Rural Stewardship agri-environment scheme, 1.5 to 6 m-wide grassy field margins attracted higher densities of foraging queen bumblebees Bombus spp. in spring than conventionally managed field margins (more than three queens/100 m on grassy margins, compared to one queen/100 m on conventional margins). However, when counts on conventionally managed field margins were compared on farms with and without agri-environment schemes, farms without the agri-environment agreement had more foraging queens. This raises the possibility that farms with the Rural Stewardship Scheme agreement supported similar numbers of queens overall, but they were preferentially distributed on the agri-environment field margins. Margins on 10 arable farms were studied, five of which participated in the Rural Stewardship Scheme. Six habitat types were studied using 100 m transects on each farm: Rural Stewardship Scheme grass margin, conventionally managed arable field margin, species rich grassland, unfarmed grassland, Rural Stewardship Scheme hedgerow, conventionally managed hedgerow. The number of bumblebee queens within 3 m of the transect were recorded, once a week over a five-week period.

61 

A replicated mark-release-recapture study in summer 2007 in Oxfordshire, UK (Merckx et al. 2009a) found overall higher abundance of nine common larger farmland moth (Lepidoptera) species in the margins and centres of arable fields with 6 m-wide perennial grass margins than in fields with standard about 1 m margins, but this varied highly between species. Six moth species which contributed to the higher abundance of moths in wide field margins were less mobile; moving a shorter distance between captures and being more frequently recaptured at the site of first capture. Nectar availability (number of flowerheads) was higher in wide margins, both for overall nectar plant species and plant species known to be moth favourites. Plant species richness and diversity was similar in hedgerows surrounding fields bordered with wide margins and with standard margins. Five Heath pattern actinic light traps (6 W) were positioned in each of four arable fields: one in the centre and one in each field margin (1 m from hedgerow). All traps were >100 m apart and >50 m from hedgerow intersections. Traps were operated on the 32 nights (dusk till dawn) with suitable weather between 5 June and 14 July. Nectar availability was assessed at each trap site on 25 June by counting the number of flowerheads present on field margins 10 m either side of the trap locations. Percentage cover and species richness of woody plant species (excluding trees) was estimated in hedges bordering the fields.

62 

A replicated, controlled study in 2006 in central Oxfordshire, UK (Merckx et al. 2009b) found no difference in moth (Lepidoptera) abundance or diversity between 6 m (agri-environment scheme option) and about 1 m (standard option) wide field margins in four lowland farmland areas. In each area, one farm with standard margins and one with 6 m-wide margins were sampled. Three Heath pattern actinic light traps (6 W) were set up on each farm ?100 m apart and >50 m from hedgerow intersections. Traps were placed on 2 m2 white cotton sheets 1 m from hedgerows bordering fields with no banks or ditches. All farms were sampled once during each of 11 discrete fortnightly periods from mid-May to mid-October 2006. Sampling was carried out from dusk till dawn during nights with suitable weather conditions. At dawn, all individuals were identified to species, species-pair or genus, marked with a unique number and released where caught.

63 

A series of three replicated trials in the Netherlands (Musters et al. 2009) found that the number of plant species in field margins and adjacent ditch banks increased in the four years following establishment of 2-3 m-wide sown grass and wildflower field margins. More field margins and ditch banks showed a decline in cover of agricultural weeds following margin establishment. For both butterflies (Lepidoptera) and dragonflies (Odonata), more than half the transects showed increased species diversity in field margins, in the two to eight years following the establishment of margins. Ninety field margins at least 2 m-wide were established on 21 farms across the Netherlands and monitored for two to six years. On 20 of the farms, 107 ditch banks alongside 3 m wide field margins were also monitored. Most margins were planted with grasses. All margins and ditch banks were mown at least once a year and cuttings removed. Plant species richness was measured in permanent quadrats or sections. Butterflies were counted in 50 m transect counts along field margins on six farms, and dragonflies on five farms. Transect counts were either every week, or two to five times during summer.

64 

A 2009 literature review of European farmland conservation practices (Vickery et al. 2009) found that sown grass margins had higher arthropod diversity than adjacent crops, and also held higher abundances of soil invertebrates. The availability of bird food-species was also higher than in crops, although use of grass-only strips by several bird species (yellowhammer Emberiza citrinella, red-legged partridge Alectoris rufa, greenfinch Carduelis chloris, linnet C. cannabina) was lower than for margins planted with wildflower mixes.

65 

A replicated study in February 2008 in East Anglia, England (Davey et al. 2010) found that field margins managed under agri-environment schemes had a positive influence on 19 out of 24 farmland bird species. However, only yellowhammer Emberiza citrinella and possibly blackcap Sylvia altricapilla showed a strong positive response to agri-environment scheme margins affecting species densities. Great tit Parus major and common starling Sturnus vulgaris showed weak positive responses. Field margins were categorized as grassy/weedy, bare/fallow or wild-bird cover (although very few fields had wild bird cover) and most were managed under the Entry Level Stewardship scheme. Ninety-seven 1 km2 plots were included in the study. All field boundaries within each square were walked and all birds present mapped. Squares were visited twice; once in April to mid-May, and once in mid-May to June.

66 

A replicated site comparison study in 2004-2008 across England (Ewald et al. 2010) found that grey partridge Perdix perdix brood size was negatively associated with the proportion of a site under planted grass buffer strips (association significant in 2008). The ratio of young:old partridges was negatively related to the proportion of grass strips in 2005 and 2008. However, year-on-year changes in partridge density and overwinter survival were positively correlated with the proportion of grass buffer strips on a site, this relationship was significant from 2006 to 2007 (year-on-year changes) and 2005-2006 (overwinter survival). Spring and autumn counts of grey partridge were made at 1,031 sites across England as part of the Partridge Count Scheme.

67 

A replicated site comparison study in three regions in England (Field et al. 2010) found that hedges alongside wildflower-rich grass field margins (‘floristically enhanced’ margins) under Higher Level Stewardship had more yellowhammers Emberiza citrinella (estimated 0.4 birds/m) compared to hedges without a grass margin (estimated 0.2 birds/m). Hedges alongside unenhanced grass margins, either conventionally managed or managed under Entry Level Stewardship, did not have more yellowhammers. Surveys were carried out on 69 farms with Higher Level Stewardship in East Anglia, the West Midlands and the Cotswolds and on 31 farms across all three regions with no environmental stewardship.

68 

A replicated study in summer 2007 in south Sweden (Haaland & Gyllin 2010) found lower densities and species richness of butterflies (Lepidoptera) and bumblebees Bombus spp. in margins mainly sown with a mix of grass species, 4 m-wide (greenways or ‘beträdor’) than in sown wildflower strips. Fourteen percent of the recorded butterflies, and 17% of the bumblebees, were found in grass strips, and butterfly density was nearly 20 times lower in grass strips than in wildflower strips. Bumblebees were almost absent in the sown grass strips. However, the presence of bushes adjacent to grass strips positively influenced butterfly species richness and abundance of both butterflies and bumblebees. Butterflies and bumblebees were recorded on three grass strips (14 transects) and one wildflower strip (six transects) on five occasions on four arable farms. Butterflies and bumblebees were counted within 2 m either side of the observer and the flower species visited by the insects noted.

69 

A replicated, controlled study in the summers of 2008-2009 in Berkshire, UK (Blake et al. 2011) found that butterfly (Lepidoptera) abundance, species richness and diversity were positively associated with the number of sown wildflower species in existing grass buffer strips. Butterfly species richness was higher in plots that had received a combined treatment of scarification and grass-specific herbicide application compared with single treatment and control plots. Butterfly abundance and diversity were higher in plots that were both scarified and treated with grass-specific herbicide than single treatment, but not control plots. Sown wildflower cover and species richness was higher in the combined treatment plots in both years, and there was a significant increase in wildflower cover from 2008 to 2009. In both years, species richness of unsown wildflowers (annuals, perennials and in total) was higher in the combined scarification/grass-specific herbicide treatments. It was also higher in scarification-only than in grass-specific herbicide-only and control plots, but it decreased in scarified plots from 2008 to 2009. Six metre-wide grass buffer strips were created on two arable farms in 2004 and managed under an Entry Level Stewardship agreement from 2005. Four treatments were randomly established within each of three replicate blocks/site in early spring 2008: scarification, selective grass-specific herbicide application, scarification and selective grass-specific herbicide, control. Scarification was always followed by sowing a wildflower seed mixture. All plots were cut in autumn and cuttings left in place. In both years vegetation was assessed once in June, in ten randomly placed 0.25 m2 quadrats within each treatment plot avoiding the edges. Percentage cover of all plant species was estimated on an eight point scale. Abundance, diversity and species richness of adult butterflies was recorded during standard transect walks along the centre of each treatment plot (25 x 4 m). Each plot was sampled eight times/year between May and September.

Referenced papers

Please cite as:

Dicks, L.V., Ashpole, J.E., Dänhardt, J., James, K., Jönsson, A., Randall, N., Showler, D.A., Smith, R.K., Turpie, S., Williams D.R. & Sutherland, W.J. (2017) Farmland Conservation Pages 245-284 in: W.J. Sutherland, L.V. Dicks, N. Ockendon & R.K. Smith (eds) What Works in Conservation 2017. Open Book Publishers, Cambridge, UK.