Action: Reduce management intensity on permanent grasslands (several interventions at once)
- A total of 32 individual studies from the Czech Republic, Germany, Ireland, the Netherlands, Switzerland and the UK looked at the effects on farmland wildlife of reducing management intensity on permanent grasslands. Twenty-two studies found benefits to some or all wildlife groups studied. Eleven studies (including four replicated site comparisons and three reviews) found reduced management intensity on permanent grassland benefited plants. Sixteen studies (including eight site comparisons of which four paired and three reviews) found benefits to some or all invertebrates. Five studies (including two replicated site comparisons, of which one paired, and a review) found positive effects on some or all birds.
- Twenty-one studies from six European countries found no clear effects of reducing management intensity on some or all plants, invertebrates or birds. Seven studies (including two replicated paired site comparisons and a review) found no clear effect on plants. Ten studies (including four site comparisons and one paired site comparison) found mixed or no effects on some or all invertebrates. Two studies (one review, one site comparison) found invertebrate communities on less intensively managed grasslands were distinct from those on intensively managed grasslands. Four studies (including three site comparisons, of which one paired and two replicated) found no clear effects on bird numbers or species richness.
- Five studies from four European countries found negative effects of reducing management intensity on plants, invertebrates or birds. Two studies (one review, one replicated trial) found some plant species were lost under extensive management. Two studies (one paired site comparison) found more invertebrates in grasslands with intensive management. One paired site comparison found fewer wading birds on grasslands with reduced management intensity than on conventionally managed grassland.
Reducing the intensity of grassland management involves reducing or stopping the use of fertilizers, herbicides and pesticides and delaying the mowing date until later in the summer. Studies included here have monitored the effects of carrying out two or more of these management interventions at the same time. All the studies included here monitor the effects of a change of grassland management, or of implementing a regime of reduced management intensity for the purpose of nature conservation, such as an agri-environment scheme.
Studies that only carry out one of these management interventions, rather than several combined, would be included under the relevant separate intervention. See: ‘Reduce inputs in permanent grassland management’, ‘Raise mowing height on grasslands’ and ‘Delay mowing or first grazing date on grasslands’.
See also ‘Pay farmers to cover the cost of conservation measures (as in agri-environment schemes)’ for a study that records the decline in species richness on upland hay meadows over time, following introduction of two main agri-environment schemes in the Yorkshire Dales, UK (Pacha and Petit 2008).
There is also a literature comparing sites without direct intervention, such as Di Giulio et al. (2001), in which wildlife on species-rich grasslands is compared with wildlife on intensive grasslands. Whilst such studies are relevant, they do not demonstrate the effects of direct intervention (reducing management intensity or imposing a reduced management intensity regime) and as such we do not include them.
Di Giulio M., Edwards P.J. & Meister E. (2001) Enhancing insect diversity in agricultural grasslands: the roles of management and landscape structure. Journal of Applied Ecology, 38, 310-319.
Supporting evidence from individual studies
A replicated site comparison study in Norfolk, UK, in 1987 (Dodd 1987) found higher diversity of plants on 20 grazing fields under the Broads Grazing Marshes Scheme than on five more intensively managed fields outside the scheme. Fields within Scheme had 14-31 plant species, those outside it 10-16 species. Plant diversity (the Shannon-Weiner index) was also higher in fields with less than 125 kg nitrogen/ha applied, fields with less than 1.5 livestock units/ha and unlimed fields. The Broads Grazing Marshes Scheme was set up in 1985. Farmers were paid to retain permanent grazed grassland at a stocking rate from 0.5 to 1.5 livestock units/acre. Only one silage cut per year was permitted, with aftermath grazing. Farmers needed permission from the Broads Grazing Scheme Unit if they wished to apply more than 125 kg N/ha, apply herbicide other than spot treatment for thistles, or carry out drainage, levelling or re-seeding. Plants were monitored in 1987 in two-hundred 25 x 25 cm quadrats placed along two diagonal axes across each field. Management practices were recorded for each field, using farmer questionnaires.
A small study from 1967 to 1993 of a grassland at the University experimental farm, Meenthoeve in the Netherlands (Wind et al. 1994) found that plant species increased for six years following extensification, but then decreased in unfertilized plots. Species increased following sowing (1966) and extensification (1971), from 19 species in 1969 to 37 in 1977. Numbers then declined to below 25 species in unfertilized plots as weeds typical of intensive grassland decreased. In 1985, a botanical change characteristic of a reduction in soil fertility occurred. Dominant species were common bent Agrostis capillaris and Yorkshire-fog Holcus lanatus in all three treatments, sweet vernal grass Anthoxantum odoratum in unfertilized treatments and red fescue Festuca rubra in the mown treatment. The 0.8 ha area of grassland had received 300 kg N/ha, phosphorous P and potassium K and grazing for five years. In 1971, it was divided into: a 0.26 ha plot with no fertilizer, sub-divided into intermittent grazing or mown for hay June and October, and a 0.56 ha plot with 20 kg/ha P2O2 and 40 kg/ha K2O per year and 5 steers/ha until 1975 followed by 3 steers/ha. Botanical composition of plots was sampled in May in ten years (1967-1993). Species were sampled by hand sorting 100 handfuls of grass/plot and taking 100 soil cores.
A review in 1997 (Fisher & Rahmann 1997) found that reduced management intensity on grassland can benefit plant and insect diversity, but it does not always. Five European studies monitored the biodiversity effects of reducing management intensity on lowland grasslands. Two of these studies (Bakker 1994, Wind et al. 1994) showed an increase in plant diversity, and one an increase in invertebrate diversity (Blake et al. 1996) following restoration of the plant community by sowing. In all three cases, the changes took many years. They covered periods of between seven and 20 years and none of the studies measured diversity equivalent to species-rich semi-natural grasslands after this time period. Two other studies (Marriott et al. 1994, Neuteboom et al. 1994) showed that reduced management intensity did not improve plant diversity. The review found no direct evidence for effects of extensification in upland grasslands.
Bakker J.P. (1994) Nature management in Dutch grasslands. Proceedings of the British Grassland Society Occasional Symposium, 28. pp 115-124.
Marriott C.A., Bolton G.R., Common T.G., Small J.L. & Barthram G.T. (1994) Effects of extensification of sheep grazing systems on animal production and species composition of the sward. Proceedings of the 16th Meeting of the European Grassland Federation. pp 505-509.
Neuteboom J.H., t'Mannetje L., Lantinga E.A. & Wind K. (1994) Botanical composition, yield and herbage quality of swards of different age on organic meadowlands. Proceedings of the 15th Meeting of the European Grassland Federation. pp 320-323.
Blake S., Foster G.N., Fisher G.E.J. & Ligertwood G.L. (1996) Effects of management practices on the carabid faunas of newly established wildflower meadows in southern Scotland. Annales Zoologici Fennici, 33, 139-147.
A 1997 review of experimental evidence (largely published in German language) (Nösberger & Kessler 1997) described an experiment on reduced management intensity in upland grassland in Wales. This showed that without cutting or grazing, important pasture species such as perennial rye grass Lolium perenne and white clover Trifolium repens were lost within two years (Fothergill et al. 1994). Both species were maintained by an annual summer cut.
Fothergill M., Davies D.A. & Morgan C.T. (1994) Extensification of upland pasture in Britain. Proceedings of the New Zealand Grassland Association, 56, 219-222.
A 1998 review of two studies (Nösberger et al. 1998) concluded that reducing management intensity on permanent grassland is likely to benefit two important pasture species, white clover Trifolium repens and meadow fescue Festuca pratensis. The first study (Schwank et al. 1986) found that frequent cutting and fertilization reduced the yield of white clover from 5% (under traditional management) to 2%. This was probably due to clover leaves growing closer to the ground and being shaded by taller plants after fertilization. A second study (Carlen 1994) concluded that the decline in meadow fescue found under intensive management results from its low competitive ability (due to small leaves and low root activity), rather than direct effects of cutting or fertilization. The study locations are not given.
Schwank O., Blum H. & Nösberger J. (1986) The influence of irradiance distribution on the growth of white clover (Trifolium repens L.) in differently managed canopies of permanent grassland. Annals of Botany, 57, 273-281.
Carlen C. (1994) Root competition and shoot competition between Festuca pratensis Huds. and Dactylis glomerata L. PhD thesis No. 10512, Eidgenössische Technische Hochschule Zürich.
A replicated, controlled study in summer 1997 and 1998 in 109 sites of two arable regions in Switzerland (Jeanneret et al. 2000) found mixed effects of reduced management intensity on grasslands on butterflies (Lepidoptera) and spiders (Araneae). For butterflies, species richness did not differ significantly between low-intensity or extensively managed meadows and intensively managed meadows, however butterfly species richness was higher in extensively managed meadows (but not in low-intensity meadows) than in cereal fields. The number of spider species was found to be higher in low-intensity meadows (but not in extensively managed meadows) than in cereal fields, but no difference was detected between extensive, low- and high-intensively managed meadows. Spider community composition differed between the intensively managed meadows and the two meadow types with reduced management intensity. The investigated habitat types were forest edges, arable fields (winter wheat and intensively managed meadow) and ecological compensation areas including hedgerows, extensively managed and low-intensity meadows, wildflower strips on set-aside land and orchard meadows. Spiders were collected in pitfall traps in May and June 1997. Butterflies were observed during six visits (10 minutes, covering 0.25 ha) in each site in 1998. This was part of the same study as (Jeanneret et al. 2003a, Jeanneret et al. 2003b).
The initial findings of a controlled replicated site comparison study of the Swiss Ecological Compensation Areas scheme in 1999-2005 (Herzog et al. 2001) found endangered plant species present on 42% of 582 grassland Ecological Compensation Areas (extensively managed meadows, litter meadows and pastures) examined in 1999. Although the number of spider (Araneae) species was similar (around 20 species), there were significant differences in spider species composition in 23 Ecological Compensation Area and 15 non-Ecological Compensation Area meadows. Butterfly (Lepidoptera) species composition also differed between Ecological Compensation Area and non-Ecological Compensation Area sites. Vascular plants, ground beetles (Carabidae), spiders, butterflies, grasshoppers (Orthoptera) and breeding birds were monitored on grasslands in three case study areas of around 5 km2.
A paired site comparison in the Netherlands (Kleijn et al. 2001) found more species of bee (Apidae) and hoverfly (Syrphidae) on grassland fields with management agreements to benefit birds or plants than on conventionally managed fields, but not more species of bird or plant. For hoverflies (but not bees) this difference was mostly in May, and could be related to vegetation height, because conventional fields were cut earlier. There were around 50 plant species/field on both field types. The number of bee species was low (average 1.7 bee species/field overall, 85% from just three species). The density of breeding bird territories was not significantly different between 20 fields with meadow bird agreements and 20 control fields, both for all bird species and just for waders. Eurasian oystercatcher Haematopus ostralegus, black-tailed godwit Limosa limosa, common redshank Tringa totanus and northern lapwing Vanellus vanellus were all significantly less abundant on management agreement fields than on control fields. There was no significant difference in the number of territories between field types for three of these species, but oystercatchers had significantly fewer territories on management agreement fields than on control fields (0.13 vs 0.52). The study involved 39 field pairs, one with either a ‘botanical agreement’ (22 field pairs) and/or a ‘meadow bird agreement’ (20 field pairs), the other managed conventionally. Fields were 2 ha on average. Paired fields were within 1 km of each other, similar in size and soil type. Fertilizer inputs were significantly lower and mowing dates later on fields with management agreements than on conventionally managed fields. Fields were surveyed between March and September 2000 (birds five times between March and June, plants and insects four times May to August). More detailed results are presented in a later paper (Kleijn et al. 2004).
A 2003 literature review in Europe (Bat Conservation Trust 2003) found one review and two studies that reported that invertebrates are affected by the frequency and timing of mowing in grassland. The one review suggested that cutting grassland twice a year was detrimental to hoverflies (Syrphidae), although responses for other families were mixed (Gerstmeir & Lang 1996). One study (Fuller et al. 2003) found that several cuts within grassland each year had a greater effect on beetles (Coleoptera) than one late cut. Another reported that responses of true bugs (Heteroptera) and plant/leafhoppers (Auchenorrhyncha) to mowing vary between species and timing of the cut (Morris 1981a,b).
Morris M. G. (1981a) Responses of grassland invertebrates to management by cutting. III. Adverse effects on Auchenorrhyncha. Journal of Applied Ecology, 18, 107-123.
Morris M. G. (1981b) Responses of grassland invertebrates to management by cutting. IV. Positive responses of Auchenorrhyncha. Journal of Applied Ecology, 18, 763-771.
Gerstmeir R. & Lang C. (1996). Beitrag zu Auswirkungen der Mahd auf Arthropoden [Effects of mowing on arthropods]. Zeitschrift fur Okologie un Naturschutz, 5, 1-14.
Fuller R., Atkinson P.W., Asteraki E. J., Conway G. J., Goodyear J., Haysom K., Ings T., Smith R.E.N., Tallowin J. R. & Vickery J. A. (2003) Changes in lowland grassland management: effects on invertebrates and birds. Defra BD1435.
A site comparison study in the regions of Ruswil, northwest of Lucerne, Switzerland (Jeanneret et al. 2003a) found the number of butterfly (Lepidoptera) species, but not spider (Araneae) or ground beetle (Carabidae) species, was significantly higher in low input meadows than in intensively managed meadows. Twenty-three low input grasslands, around 400 m2 in size and managed as Ecological Compensation Areas were surveyed. There were two types: 16 ‘extensively used meadows’ with late mowing and no fertilizer and seven ‘low-input meadows, with late mowing and restricted fertilization (up to 60 kg N/ha/year). For comparison, fifteen intensively managed meadows were surveyed: seven conventional grasslands and eight Ecological Compensation Area meadows in traditional orchards with no restrictions on cutting or fertilizer use. Spiders and ground beetles were monitored using pitfall traps set over five weeks of May and June 1997. Butterflies were observed for ten minute periods on 0.25 ha of each site, on five occasions from May to August 1998, between 10:00 and 17:30 on sunny days with temperatures of at least 18°C. More detailed results (in German) are presented in (Jeanneret et al. 2000).
The same team as in (Jeanneret et al.2003a) combined the results from Ruswil with another region - Rafz, northwest of Zurich, Switzerland (Jeanneret et al. 2003b). It also found that butterfly (Lepidoptera) species richness was significantly higher in extensively managed and low input meadows than in intensively managed meadows. The same comparison was not possible for spider (Araneae) and beetle (Coleoptera) data, because pitfall traps were set for one week longer in one of the regions. Thirty-five low input grasslands managed as Ecological Compensation Areas were included, 23 in Ruswil and 12 in Rafz. There were two types: 19 ‘extensively used meadows’ with late mowing and no fertilizer and 16 ‘low-input meadows, with late mowing and restricted fertilization (up to 60 kg N/ha/year). In Ruswil, seven permanent intensively managed meadows and eight Ecological Compensation Area meadows in traditional orchards (intensively managed because they had no restrictions on cutting or fertilizer use) were sampled for comparison. Butterflies were observed for 10 minute periods on 0.25 ha of each site, on five occasions from May to August 1998. More detailed results (in German) are presented in (Jeanneret et al. 2000).
A replicated, controlled, paired sites study in August in 21 field pairs in three farmland regions (Bauma, Ruswil and Flühli) in Switzerland (Jöhl et al. 2004) found higher species richness and abundance of grasshoppers (Orthoptera: Caelifera) in low-intensity meadows than in intensively managed meadows. Species richness and the number of rare species were higher in low intensity meadows in two regions (Bauma: average 4.4 vs 2.9 species and Flühli: 5.9 vs 4.6 spp.), but no difference was found between the meadow types in Ruswil (2.6 spp. both). Grasshopper abundance was higher in low intensity meadows than in intensively managed meadows in all regions (Bauma: average 24.07 vs 24.14 individuals/; Ruswil: 22.29 vs 19.71 ind.; Flühli: 26.21 vs 21.93 ind.). Transect location (field edge or centre) did not affect grasshopper species richness or abundance. Seven field pairs (each consisting of one low intensity and one intensive meadow with similar environmental conditions) were investigated in each region. Grasshoppers were monitored in August along two 95 m long transects in each meadow (one along the field edge and one in the field centre). Transects were walked slowly for 15 minutes, and all observed grasshoppers were caught to determine species richness and grasshopper density.
Further analysis of data (Kleijn et al. 2004) from the same replicated paired site comparison in the Netherlands as (Kleijn et al. 2001) found that meadow songbirds, bees (Apidae) and hoverflies (Syrphidae) were more abundant on fields with management agreements to benefit plants or birds (only fields with bird agreements analysed for birds). Wading birds were less abundant on 20 fields with meadow bird agreements (average seven birds and 1.3 territories/field compared to 12 birds and 2.1 territories on 20 conventional fields). Meadow songbirds were more abundant on agreement fields at a 12.5 ha scale (9.9 birds/12.5 ha plot surrounding the field, compared to 7.7 on conventional fields). Duck and non-meadow bird breeding densities did not differ between management types at either the field, or 12.5 ha scale. There were 10-15 hoverfly species and 1.5-4.0 bee species/field on fields with agreements, compared to 8-13 hoverfly species and 0.5-2.0 bee species on conventional fields. Hoverfly abundance was also higher (50-125 hoverflies/ agreement field vs 50-60 hoverflies/ conventional field). Bee abundance was higher on agreement fields for two out of three soil types (3-7 vs 1-8 bees/field). Numbers of plant species were not higher on agreement fields (approximately 14-16 plant species/20 m2 on fields under botanical agreements vs 14-15/20 m2 on conventional fields).
A site comparison study in three regions of the Swiss Plateau (Aviron et al. 2005) found more butterfly (Lepidoptera) species on low input than on intensively managed grasslands in one of two study years. In 2002, but not in 2000, low input grasslands had more butterfly species than intensively managed grasslands (actual numbers not given). The identity of the butterfly species found was not significantly influenced by management intensity, but was different in different regions. Butterflies were recorded in 56 low input grasslands and 48 intensively managed grasslands, during the summers of 2000 and 2002. The low input grasslands were managed as Ecological Compensation Areas. They had restricted fertilizer and pesticide use, and late mowing.
A replicated, controlled study of pasture in County Meath, Ireland (Helden et al. 2005) found that reduced management intensity resulted in increased species richness of spiders (Araneae) and true bugs (Hemiptera), but not beetles (Coleoptera), flies (Diptera) or bees/wasps/ants (Hymenoptera). Plots compatible with the Rural Environment Protection Scheme (0.82 ha/cow units, 88 kg N/ha) had a significantly higher species richness of spiders (3 species/paddock) and true bugs (7 species) compared to conventional plots (0.65 ha/cow units, 220 kg N/ha; 2 and 5 species respectively). There was no significant difference between treatments for beetles, flies or bees/wasps/ants. Four blocks were established, each with one replicate of the two management systems. Each treatment was sub-divided into three grazing paddocks grazed in a fixed sequence. Arthropods were sampled using a Vortis suction sampler once per paddock in August 2003.
A site comparison study in the regions of Nuvilly and Ruswil, Switzerland (Jeanneret et al. 2005) found that spider (Araneae), ground beetle (Carabidae) and butterfly (Lepidoptera) communities on low input grasslands were distinct and different from those on intensively managed grasslands. The study used some of the same sites as (Jeanneret et al. 2003b). The difference was strongest for spider communities. The study was carried out on 33 low input grasslands managed as Ecological Compensation Areas - 23 ‘extensively used meadows’ with late mowing and no fertilizer and 10 ‘low-input meadows’, with late mowing and restricted fertilization (up to 60 kg N/ha/year). For comparison, there were 24 intensive meadows: eight permanent intensively managed meadows, 14 Ecological Compensation Area meadows in traditional orchards and two seeded Ecological Compensation Areas. These latter Ecological Compensation Area grassland types were considered intensively managed because they had no restrictions on cutting or fertilizer use. Spiders and ground beetles were monitored for three or four years between 1997 and 2003. Butterflies were monitored in three years between 2000 and 2004.
A 2006 review on the effects of the Swiss Ecological Compensation Areas scheme in Switzerland (Herzog et al. 2006) found that out of 1,401 Ecological Compensation Area meadows investigated, only around 25% reached the required minimum quality, containing indicator plant species of species-rich semi-natural grasslands. The remaining 75% of Ecological Compensation Area meadows were species-poor with a simple vegetation structure. Several case studies showed that the community composition of spiders (Araneae) differs between extensively and conventionally managed meadows. No details on study design, monitoring techniques or other methods were given.
A replicated site comparison study of 42 fields in Switzerland (Kleijn et al. 2006) (same study as (Knop et al. 2006)) found that a number of wildlife groups benefited from fields participating in the Ecological Compensation Area scheme. There were more birds, but not more bird breeding territories in fields participating in the Ecological Compensation Area scheme than in conventionally farmed fields. There was no difference in the number of bird species on each type of farmland. There were also more uncommon species of arthropod (not endangered), significantly more bee (Apidae) and plant species and a greater density of uncommon plant species on Ecological Compensation Area grasslands than conventionally managed grassland. Ecological Compensation Areas are typically hay meadows farmed at low intensity: no fertilizers or pesticides (except for patch-wise control of problem weeds) are permitted, and vegetation must be cut and removed at least once a year - but not before 15 June (lowlands) or early July (mountains). The study surveyed seven pairs of fields (one within an Ecological Compensation Area, one conventionally farmed) from each of three different parts of Switzerland. Diversity and abundance of vascular plants, arthropods and birds were measured using standard sampling methods in late spring and summer 2003. Surveys of observed and territory-holding birds were made at the field scale and at the 1 ha plot scale.
A replicated trial with paired sites in Switzerland (Knop et al. 2006) (same study as (Kleijn et al. 2006)) found 21 hay meadows managed under the Ecological Compensation Areas agri-environment scheme for three to 10 years had more species of plant, wild bee (Apidae) and grasshopper (Orthoptera) than 21 paired conventionally managed hay meadows. There were 13 wild bee species/field, 11 individual bees/survey under the agri-environment schemes, compared to 11 bee species/field and 8 individuals/survey on conventional meadows. This agri-environment scheme requires a postponed first cut, in June or later, and no additions of fertilizer or pesticide to the meadow, although in the study three of the trial meadows were fertilized a little, despite the regulations.
A replicated trial in 2004 of 13 meadows managed under the Swiss Ecological Compensation Area agri-environment scheme for at least five years (Albrecht et al. 2007) found that the species richness and abundance of hoverflies (Syrphidae), solitary bees (Apidae) and large-sized pollinators (mainly social bees and butterflies (Lepidoptera)) visiting potted flowering plants were higher in meadows under the scheme than in adjacent, intensively managed meadows. The total area of each Ecological Compensation Area meadow (0.48 - 2.15 ha) had no significant influence on the wild pollinator communities in this study.
A site comparison study from 1998 to 2004 in two areas of the Swiss Plateau region (Aviron et al. 2007) found significantly more species of butterfly (Lepidoptera) on Ecological Compensation Area grassland than conventional grassland in one of the two areas. In Nuvilly, there was an average of 12 species on Ecological Compensation Area grasslands and 11 species on conventional grasslands. In Ruswil, there was an average of 3.4 species on Ecological Compensation Area grasslands and 2.6 species on conventional grasslands. When other factors such as number of plant species, coverage of woody plants or distance to forest were taken into account, this difference was only statistically significant in Ruswil, and not in Nuvilly. Ecological Compensation Area sites tended to have more ‘specialist’ species - those with only one generation per year, poor dispersal ability or larvae that eat only one type of plant. There were 20-22 Ecological Compensation Area meadows and 6-16 conventional grasslands. The conventional grasslands were fertilized with an average of 206 kg N/ha and cut on average three times each year. The Ecological Compensation Area grasslands were fertilized with an average of 7 kg N/ha and cut on average twice a year.
A replicated before-and-after trial of 116 upland hay meadows in the Pennines, northern England (Critchley et al. 2007a) found that reduced management intensity prescribed under the Environmentally Sensitive Areas agri-environment scheme led to increased plant species richness in areas where the plant community was degraded. At sites with areas of degraded or modified plant communities, the average number of plant species increased slightly (from 21.6 to 22.8 species/m2 for areas with species-rich but not MG3 (sweet vernal grass Anthoxanthum odoratum-wood crane’s bill Geranium sylvaticum grassland) plant communities (data from 62 sites), and from 17.6 to 19.1 species/m2 for degraded areas (data from 90 sites)). This increase was predominantly in the number of grass species, not broadleaf herbaceous species. Plant species were recorded in three 1 m2 permanent quadrats at each site, in 1987 (the year the scheme was introduced) and 2002.
A replicated trial in the Pennine Dales, UK (Critchley et al. 2007b) found that plant species richness declined on 147 upland hay meadows managed under the Environmentally Sensitive Areas scheme between 1995 and 2002. Eighty-seven sites under Tier 1 of the scheme allowed 125 kg/ha of nitrogen, phosphorous, potassium (NPK) fertilizer/year, 12.5 tonnes/ha of manure, cutting after 8 July, with grazing allowed until 7 weeks before cutting. Sixty sites under Tier 2 of the scheme allowed no mineral fertilizer, 12.5 tonnes/ha of manure, cutting after 15 July, with no grazing after 15 May. Lime addition and herbicide were allowed with written approval under both Tiers. Tier 1 sites had an average of three fewer plant species in 2002 than in 1995. Tier 2 sites had on average 1.5 fewer species. The fall in species richness was significant for herbaceous (forb) species, but not for grass species. Sweet vernal grass Anthoxanthum odoratum, wood cranesbill Geranium sylvaticum, meadow buttercup Ranunculus acris and yellow rattle Rhinanthus minor were all less frequently found in 2002 than in 1995.
A randomized, replicated, controlled trial from 2003 to 2006 in southwest England (Defra 2007) found that plots of permanent pasture cut just once in May or July or not at all during the summer and left unfertilized supported greater numbers and more species of beetles (Coleoptera) in suction traps, true bugs (Hemiptera) and planthoppers (Auchenorrhyncha), greater abundances of spiders (Araneae), craneflies (Tipulidae) and St Mark’s flies Bibio marci and more species of woodlice (Isopoda) than control fertilized plots cut in May and July, as in conventional silage management. Small insectivorous birds (dunnock Prunella modularis, wren Troglodytes troglodytes and robin Erithacus rubecula) and seed-eating finches (Fringillidae) and buntings (Emberizidae) preferred extensively managed treatments (particularly the plots uncut in summer) to control plots for foraging. Experimental plots (50 x 10 m) were sown on four farms. There were twelve replicates of each management type, monitored over four years. Results from the same study are also presented in (Pilgrim et al. 2007, Woodcock et al. 2007, Potts et al. 2009).
A site comparison study of alpine meadows in the Albula and Surses Valleys in the Canton of Grisons, Switzerland (Dietschi et al. 2007) found that low intensity meadows and extensively managed meadows had significantly more plant species than intensively managed meadows. Low intensity meadows had on average 50 and 55 plant species for moist and dry meadows respectively. Extensive meadows had averages of 53 and 58 plant species for moist and dry meadows respectively. Intensively managed meadows had 37 plant species on average (none were dry meadows). The difference in species number between low intensity and extensive meadows was not statistically significant. Sixty-nine sites were surveyed. Thirty extensively managed meadows had no fertilizer input. Twenty-five meadows managed with low intensity had manure inputs equivalent to 30 kg N/ha/year. Both these types of meadow were managed under agri-environment management agreements, and were cut once after 15 July, with autumn grazing allowed. Fourteen intensively managed meadows had fertilizer inputs of around 90 kg N/ha, and were cut three or four times a year without restrictions. The authors suggest that low intensity management retains species richness in alpine meadows (unlike lowland grasslands in Switzerland) because their degradation due to intensive management has been relatively recent.
A replicated, controlled study in 1999-2001 and 2004-2005 in Jutland, Denmark (Kahlert et al. 2007), found that permanent grassland fields under an agri-environment scheme designed to increase water levels had significantly higher numbers of three species of wading bird (northern lapwing Vanellus vanellus, black-tailed godwit Limosa limosa, common redshank Tringa totanus) after the scheme was implemented (2004-2005), compared to numbers before the scheme (1999-2001). Eurasian oystercatchers Haematopus ostrolagus did not increase. Effects of the scheme varied between restored and permanent grasslands, and between wet and dry fields. The scheme involved promoting wet grasslands as well as reducing fertilizer inputs, grazing pressure and the period of mowing. A total of 615 fields were studied. The four species were surveyed twice during the breeding season (April-May), and the number of each species and their location recorded.
A replicated trial in the Netherlands (Kohler et al. 2007) found that an agri-environment scheme aimed at enhancing habitat for birds by reducing fertilizer and pesticide input and delaying cutting or grazing had no impact on diversity of non-Apis spp. bee or plant species in 21 Dutch wet meadow fields when compared with paired conventionally managed fields. Bee diversity and abundance was low in both field types (average <3 species/field; <6 individuals per field). This agri-environment scheme allowed application of nitrogen fertilizer at 206 kg/ha, which is 75% of the standard fertilizer application rate (269 kg/ha). The meadows had been under the scheme for between three and 10 years.
In the same randomized, replicated, controlled trial as (Defra 2007) in southwest England, (Pilgrim et al. 2007) found that 50 x 10 m plots of permanent pasture cut just once in May or July or not at all during the summer and left unfertilized had a greater total diversity of invertebrates than control fertilized plots cut in May and July. There were twelve replicates of each management type, monitored over five years (2002-2006). This study was also part of the same study as (Woodcock et al. 2007, Potts et al. 2009)).
In the same randomized, replicated, controlled study as (Defra 2007) in southwest England, (Woodcock et al. 2007) found that 50 x 10 m plots of permanent pasture cut just once in July or not at all during the summer and left unfertilized attracted a greater abundance and more species of beetle (Coleoptera) than control fertilized plots cut in May and July, in the third year of monitoring. Plots without fertilizer added also had higher proportions of seed- and flower-feeding beetle species in the community. There were twelve replicates of each management type, monitored over three years (2003-2005). This study was also part of the same study as (Pilgrim et al. 2007, Potts et al. 2009)).
A replicated, randomized study of pasture at three sites in Ireland (Curry et al. 2008) found that overall, earthworm (Lumbricidae) density and biomass tended to increase with management intensity (nitrogen fertilizer input and stocking rate), but that results varied with site. At Solohead there was no significant relationship between management intensity (N fertilizer input: 80, 175, 225 and 350 kg N/ha; stock rate: 1.75–2.5 cows/ha) and density or biomass. At Johnstown Castle, density and biomass increased with fertilizer input (0, 225 and 390 kg N/ha/year), but the effect was only significant in spring (density: 140, 235, 280/m²; biomass: 60, 115, 160 g/m² respectively). At Grange, biomass, but not density, was significantly higher in the 225 kg N and 2.4 cow units/ha treatment than the 100 kg N and 1.7 cow units/ha plots in autumn (92 vs 60 g/m²), but not spring (69 vs 58 g/m²). However, out of ten species at Grange, only two were significantly more abundant with higher inputs; species abundance did not vary with input at the other sites. Treatments were laid out as randomized blocks with five, three and four replicates (of 1-2 ha) for each treatment at Solohead, Johnstown Castle and Grange respectively. Earthworms were sampled using the formalin method within six 0.5 x 0.5 m quadrats/plot during one spring and autumn at each site from 2003 to 2005.
A replicated paired site comparison in Bavaria, Germany (Mayer et al. 2008) found that most grasslands managed extensively under the Bavarian ‘Agricultural Landscape Programme’ (KULAP) did not have more plant species than paired control sites, but sites with a strict regime of no chemical fertilizers or pesticides as part of the agreement did have more plant species. There were 17-20 plant species/site on both agreement and control sites (314 site pairs). These agreements restricted chemical pesticide use and livestock stocking rates (0.5-2.5 units/ha). Fertilizer use was allowed on 189 of the sites, mineral fertilizer was not allowed on 125 sites, but these two types were analysed separately and neither showed a difference in numbers of plant species. Another set of 91 site pairs where agreement sites had delayed cutting date (first cutting dates of 1 July or 15 June, combined with maximum of two livestock units/ha, no mineral fertilizer) were also not different from paired control sites (21-24 plant species/site). There were more plant species on grasslands with no chemical pesticide or fertilizer inputs allowed (also limited to 2 livestock units/ha; 57 site pairs). These sites had around 22 plant species/site, compared to around 18 species/site on paired control sites. Pairs of 25 m2 grassland plots were selected from 4,400 plots in the Bavarian grassland survey. All plant species within the plot were recorded between April and October (year not given). Plot pairs were in the same natural landscape, 90% within 10 km of each other. In each pair, there was one with and one without an agri-environment scheme agreement.
A site comparison study between 1997 and 2004 in two regions of central Switzerland (Aviron et al. 2009) found that Ecological Compensation Area meadows contained significantly more species of plant, butterfly (Lepidoptera) and ground beetle (Carabidae) than conventionally managed meadows, but not more species of spider (Araneae). Estimated total numbers of species were 118 plant, 36 butterfly (Lepidoptera), 98 ground beetle (Carabidae) and 156 spider on Ecological Compensation Area meadows and 83, 34, 88 and 124 on conventional meadows respectively. The study sampled 315 Ecological Compensation Area meadows and 216 conventionally managed grasslands between 1997 and 2004. Rare or threatened species were not found more frequently on Ecological Compensation Area sites. The increased number of species was a response of common species.
A replicated trial from 2004 to 2008 in the Czech Republic (Holubec & Vymyslický 2009) found that the number of plant species did not increase or decrease over five years of monitoring on grasslands under various agri-environment schemes, but the proportion of weedy nitrogen-loving species, such as nettle Urtica dioica, fell relative to typical meadow species. This change was considered a botanical improvement. Forty-seven grassland sites were monitored in May/June and October each year from 2004 to 2008. Sixteen sites were managed under ‘ecological agriculture’ and nine under grassland management agri-environment schemes. These allowed up to 60 kg N/ha fertilizer, two cuts and cattle grazing. Nine sites were wet and peaty meadows, on which no fertilizer was allowed. Twelve sites were known locations of nesting corncrake Crex crex. One site was an arable field reverted to grassland.
In the same randomized, replicated, controlled trial as (Defra 2007) from 2003 to 2006 on four farms in southwest England, (Potts et al. 2009) found plots of unfertilized permanent pasture cut just once in July or not cut at all during the summer attracted more adult butterflies (Lepidoptera) (but not more butterfly species or common bumblebees Bombus spp.) than control fertilized plots cut in May and July, managed as in conventional silage management. Plots cut just once in May, plots cut twice either unfertilized or ungrazed, and plots with a higher cutting height did not support more adult butterflies than control plots. Butterfly larvae were more abundant in unfertilized plots cut just once in May or July, or not at all in summer, than in other treatments. None of the grass treatments supported more common bumblebee species or individuals than control plots. No more than 2 bumblebees/transect were recorded on average on any grassy plot in any year. Experimental plots 50 x 10 m were established on permanent pastures (more than five-years-old) on four farms. There were nine different management types, with three replicates/farm, monitored over four years. Seven management types involved different management options for grass-only plots, including conventional silage practices, no cutting in summer, early summer cut (May), late summer cut (July), raised mowing height. Bumblebees and butterflies were surveyed along a 50 m transect line in the centre of each experimental plot, once a month from June to September annually. Butterfly larvae were sampled on two 10 m transects using a sweep net in April and June-September annually. This study was also part of the same study as (Pilgrim et al. 2007, Woodcock et al. 2007).
A paired site comparison in Switzerland in 2003 and 2004 (Albrecht et al. 2010) found that 24 Ecological Compensation Area meadows supported more species of plant and arthropod on average than adjacent intensively managed meadows. Ecological Compensation Area meadows were cut an average of two times during the year after 15 June and not fertilized. They had been managed in this way for at least five years. Intensive meadows were cut on average over four times, usually beginning in early May, and treated with liquid manure. Around 16 plant species and 75 arthropod species per site were recorded in Ecological Compensation Area meadows, compared to around 10 plant species and 60-65 arthropod species in intensively managed meadows. Of the 234 arthropod species for which more than five individuals were recorded, 147 (63%) were more abundant in Ecological Compensation Area meadows than in adjacent intensively managed meadows. Spiders (Araneae) and beetles (Coleoptera) (the two most abundant taxa), and consequently total arthropod counts, were more abundant in intensively managed meadows.
A 2010 review of four experiments on the effects of agri-environment measures on livestock farms in the UK (Buckingham et al. 2010) found two replicated trials in southwest England showing that reduced management intensity on permanent grasslands benefits foraging birds. Both found higher numbers of invertebrates, seed heads and foraging birds at lower management intensity (less fertilizer, less cutting, less grazing or a combination of these). One study was the Potential for Enhancing Biodiversity on Intensive Livestock Farms (PEBIL) project, also reported in (Defra 2007) (Defra report BD1444). The other was part of a Defra-funded project focussed largely on the effects of reduced grazing pressure (BD1454) for which no reference is given in the review.
A replicated controlled study in 2006-2009 on four intensively managed fields in Herefordshire and Yorkshire, UK (Defra 2010) found that plant seed heads and invertebrates, including important bird food invertebrates, were more abundant on plots with reduced management intensity (lighter grazing, seasonal removal of livestock, reduced fertilizer inputs) than on intensively managed plots. The cover of injurious weeds remained low on all plots throughout the study. Grasses were more abundant and broadleaved plants (forbs) less abundant on reduced management intensity plots with light grazing compared to controls. There were four 0.6 ha treatment plots/field: grass height maintained at either 12-16 cm (lenient) or 6-9 cm (moderate) by cattle April to mid-July with livestock removal from mid-July to the following spring and reduced fertilizer inputs (50 kg N/ha/year); moderate grazing with no livestock removal and either reduced (control) or normal (fertilized control: 150 kg/ha/year) fertilizer inputs. Vegetation cover was sampled in four 1 m2 quadrats/plot in July 2006 and 2009, weed cover was sampled within a 10 m radius of vegetation quadrats. Seed heads were counted in September-October 2007 and 2009 at 20 points/plot in 0.25 m2 quadrats. Invertebrates were sampled on transects 10, 30, 50, 70 and 90 m from the field boundary using Vortis sampling, pitfall traps and sweep nets.
A replicated site comparison study in 2008 and 2009 on farms in three regions in England (Field et al. 2010) found that grassland managed under Higher or Entry Level Stewardship Schemes with low or very low inputs was not used significantly more by seed-eating farmland songbirds than improved grassland or open rough grassland. Between 0.5 and 2 birds/ha were recorded on average on the different types of grassland. The stewardship grassland category also included land being maintained as semi-natural grassland under the schemes. It is not clear how many sites of the different management types were used in the analysis. Surveys were done in the summers of 2008 and 2009 on 69 farms with Higher Level Stewardship in East Anglia, the West Midlands or the Cotswolds and on 31 farms across all three regions with no environmental stewardship.
A randomized, replicated, controlled trial in Berkshire, UK started in 2008 (Pywell et al. 2010) found that grassland plots sown with a seed mix containing legumes and other broadleaved plant species had more pollinators (bees (Apidae), butterflies (Lepidoptera) and hoverflies (Syrphidae)) and pollinator species in the first summer if left uncut in July and August. Plots were either cut twice in May-June and September, with a summer rest period, or cut three times, also in July-August. The number of silage cuts (two or three) did not affect the cover of sown plant species. In this study, a summer rest from grazing, between May and September had a similar effect. There were four replicates of each treatment, on plots either 16 x 32 m (those cut for silage) or 25 x 50 m (grazed plots).
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