Action: Convert or revert arable land to permanent grassland
- All seven individual studies (including four replicated studies, of which two also controlled and a review) looking at the effects of reverting arable land to grassland found no clear benefit to wildlife. The studies monitored UK birds in winter and summer, wading birds in Denmark, grey partridges, brown hares in the UK, and plants in the Czech Republic.
- One of the studies, a controlled before-and-after study from the UK, showed that grey partridge numbers fell significantly following the reversion of arable fields to grassland.
This intervention involves changing from an arable crop to a sown agricultural grassland, to be used for grazing or silage. It is not the same as the creation of species-rich or other semi-natural grasslands.
See also ‘Provide (or retain) set-aside areas’ for some studies where non-rotational set-aside land was sown with grass, but managed as set-aside rather than as permanent agricultural grassland.
Supporting evidence from individual studies
A replicated study from 1992 to 1994 in the South Downs Environmentally Sensitive Area, Sussex, UK (Wakeham-Dawson 1995) found that foraging brown hares Lepus europaeus generally avoided farms and areas of farms that had been converted from arable crops to Environmentally Sensitive Area grasslands. Four arable, 10 mixed and three pastoral farms were studied. Hares were sampled by spotlight counting over an average of 26% of the area of each farm between November and March (1992-1993, 1993-1994).
A controlled before-and-after study from 1970 to 1994 in Sussex, England (Aebischer & Potts 1998), found that grey partridge Perdix perdix numbers declined rapidly on arable fields following their reversion to grassland, which began in 1987 (average 6.5 coveys (flocks)/km2 in 1970-1986 vs 1.1 coveys/km2 in 1987-1994). There was a considerably smaller decline on arable fields that were not reverted to grassland (average 4.9 coveys/km2 in 1970-86 vs 2.5 coveys/km2 in 1987-1994). Fields that were reverted had been favoured by partridges prior to reversion, in comparison to arable fields, but were less favoured after reversion, equating to a 23% per year decrease in relative habitat quality. Fields in a 28 km2 area were surveyed for grey partridges in late August/early September after the autumn harvest by driving across fields at dawn and dusk and mapping the position of each observation.
A replicated, controlled study in the winters of 1994-1997 in southern England (Wakeham-Dawson & Aebischer 1998) (same study as Wakeham-Dawson et al. 1998) found that Eurasian skylarks Alauda arvensis, corn buntings Miliaria calandra and meadow pipits Anthus pratensis were not consistently more abundant on arable land reverted to grassland than on intensively managed permanent grassland or winter wheat fields (4-11 skylarks/km2 on reverted fields vs 0-10 and 1-8 on permanent grassland and winter wheat; 0.1-0.2 corn buntings/km2 on reverted fields vs 0 and 0-1; 0-1.1 meadow pipits/km2 on reverted fields vs 0 and 0-4). Densities of rooks Corvus frugilegus did not differ across field types. Reverted arable fields were sown with agricultural grass mixtures and managed under specific guidelines, whilst the permanent grassland fields were mown frequently and fertilized. Fields on forty farms were surveyed. Birds were surveyed once during December and January on 217 fields in winter 1994-1995, repeated on 205 fields in winter 1995-1996 and on 225 fields in winter 1996-1997.
A replicated, controlled study in spring and summer from 1994 to 1996 in southern England (Wakeham-Dawson et al. 1998) (same study as Wakeham-Dawson & Aebischer 1998) found that arable fields reverted to permanent grassland had similar densities of Eurasian skylarks Alauda arvensis to winter wheat and intensively managed permanent grassland, except in summer 1994 when they had significantly higher densities, and summer 1995 when they had lower densities than winter wheat. In summer 1994 there were 11.9 birds/km2 on reverted fields (65 fields) vs 2.6 and 4.4 on permanent grassland (29 fields) and winter wheat (47 fields) respectively. In summer 1995 there were 2.1 birds/km2 on reverted fields (15 fields) vs 3.0 and 11.0 on permanent grassland (seven fields) and winter wheat (26 fields); in other seasons 5.7-9.1 birds/km2 on reverted fields vs 3.6-4.0 and 8.5-13.0 on permanent grassland and winter wheat. Densities of carrion crows Corvus corone tended to be higher on reverted arable land, significantly so in some seasons (1.8-4.8 birds/km2 on reverted fields vs 0-3.0 and 0-1.1 on permanent grassland and winter wheat). Rooks C. frugilegus were never found on winter wheat. Fields on forty farms were surveyed. In 1994 and 1996 between 65 and 82 reverted arable fields each sown with agricultural grass mixtures and managed under specific guidelines were studied, as well as 15-29 permanent grassland fields which were frequently mown and fertilized, and 38-47 winter wheat fields. In 1995, 15 reverted arable fields, seven permanent grassland fields and 26 winter wheat fields were surveyed. The number and locations of singing skylarks were recorded in April-May and June-July in 1994 and 1996 and in May-June 1995. The locations of foraging carrion crows and rooks were also recorded in 1994 and 1996.
A 2000 literature review (Wakeham-Dawson & Smith 2000) looked at grassland management practices in the UK. It reported three studies that found reversion of arable land to permanent grassland resulted in decreased abundance of broad-leaved weed seeds (Wakeham-Dawson & Aebischer 1998) (in downland Environmentally Sensitive Areas), and lower densities of grey partridge Perdix perdix and corn bunting Miliaria calandra (Potts 1997, Wakeham-Dawson 1997). A further two studies found breeding corn bunting and Eurasian skylark Alauda arvensis abandoned arable reversion grassland fields that were mown and grazed during the nesting season (Wakeham-Dawson 1997, Wakeham-Dawson et al. 1998).
Potts G.R. (1997) Cereal farming, pesticides and Grey Partridges. Pages 150-177 in: D.J. Pain & M.W. Pienkowski (eds.) Farming and Birds in Europe. The Common Agricultural Policy and its Implications for Bird Conservation, Academic Press, London.
Wakeham-Dawson A. (1997) Corn Buntings Miliaria calandra in the South Downs and South Wessex Downs Environmentally Sensitive Areas (ESAs), 1994-1995. Pages 186-190 in: P.F. Donald & N.J. Aebischer (eds.) The Ecology and Conservation of Corn Buntings Miliaria calandra, UK Nature Conservation No. 13, Joint Nature Conservation Committee, Peterborough.
A replicated, controlled study in 2004 and 2005 in Jutland, Denmark, (Kahlert et al. 2007) found that populations of four wading birds (northern lapwing Vanellus vanellus, black-tailed godwit Limosa limosa, common redshank Tringa totanus and Eurasian oystercatcher Haematopus ostrolagus) did not increase on newly created grasslands (formerly croplands), whether or not they were under a scheme designed to increase water levels in fields. There were population increases on some other field types. A total of 615 fields were studied, comprising permanent grassland, reverted grassland and cultivated fields in rotation. The four species were surveyed twice during the breeding season (April-May), and the number of each species and their location recorded.
A site comparison study from 2004 to 2008 in the Czech Republic (Holubec & Vymyslický 2009) found that one arable reversion field had the lowest number of plant species out of 47 grassland sites managed under different agri-environment schemes. Only five plant species were recorded over five years of monitoring on the arable reversion site, compared to a maximum of 26 plant species at other sites. No increase in species richness was observed during the monitoring period. The agri-environment management allowed up to 60 kg Nitrogen/ha fertilizer, two cuts and cattle grazing. Forty-seven grassland sites were monitored in May/June and October each year from 2004 to 2008. All plant species on each site were recorded, and plant diversity measured in a permanent 3 x 3 m quadrat.
A replicated site comparison study from 2004 to 2008 in England (Ewald et al. 2010) investigated the impact of restoration of different grasslands on grey partridge Perdix perdix. There was a negative relationship between a combined intervention (grassland restoration, scrub restoration and control and rough grazing) and the ratio of young to old partridges in 2008. The study does not distinguish between the individual impacts of grassland restoration, scrub restoration and control and rough grazing. Spring and autumn counts of grey partridge were made at 1,031 sites across England as part of the Partridge Count Scheme.
- Wakeham-Dawson A. (1995) Hares and skylarks as indicators of environmentally sensitive farming on the South Downs. PhD thesis. The Open University.
- Aebischer N.J. & Potts G.R. (1998) Spatial changes in grey partridge (Perdix perdix) distribution in relation to 25 years of changing agriculture in Sussex, U.K. Gibier Faune Sauvage, Game Wildlife, 15, 293-308
- Wakeham-Dawson A. & Aebischer N.J. (1998) Factors determining winter densities of birds on environmentally sensitive area arable reversion grassland in southern England, with special reference to skylarks (Alauda arvensis). Agriculture, Ecosystems & Environment, 70, 189-201
- Wakeham-Dawson A., Szoszkiewicz K., Stern K. & Aebischer N.J. (1998) Breeding skylarks Alauda arvensis on Environmentally Sensitive Area arable reversion grass in southern England: survey-based and experimental determination of density. Journal of Applied Ecology, 35, 635-648
- Wakeham-Dawson A. & Smith K.W. (2000) Birds and lowland grassland management practices in the UK: an overview. Ecology and Conservation of Lowland Farmland Birds. Spring Conference of the British Ornithologists' Union, 27-28 March 1999, Southampton, UK, 77-88.
- Kahlert J., Clausen P., Hounisen J. & Petersen I. (2007) Response of breeding waders to agri-environmental schemes may be obscured by effects of existing hydrology and farming history. Journal of Ornithology, 148, 287-293
- Holubec V. & Vymyslicky T. (2009) Botanical monitoring of grasslands after the adoption of agro-environmental arrangements. Grassland Science in Europe, 14, 128-131
- Ewald J.A., Aebischer N.J., Richardson S.M., Grice P.V. & Cooke A.I. (2010) The effect of agri-environment schemes on grey partridges at the farm level in England. Agriculture, Ecosystems & Environment, 138, 55-63