Mow before or after seeding/planting
Overall effectiveness category Evidence not assessed
Number of studies: 10
Background information and definitions
Mowing involves cutting grass to a uniform height with specialized machinery. This may help to maintain or increase grassland diversity as well as reducing the abundance of woody plant species. Combining mowing with sowing of seeds or planting may further help to promote diversity by introducing plant species that were not previously present.
The studies detailed in this intervention are direct tests of the effectiveness of mowing before or after seeding or planting (e.g. by comparison with an unmown but seeded or planted plot). Studies that represent comparisons of seeding to unseeded plots can be found in the actions ‘Sow grass seeds’, ‘Sow grassland forb species’ or ‘Sow native grass and forbs’.
Collins, S.L., Knapp, A.K., Briggs, J.M., Blair, J.M. & Steinauer, E.M. (1998) Modulation of diversity by grazing and mowing in native tallgrass prairie. Science, 280, 745–747.
Supporting evidence from individual studies
A replicated, controlled study in 1986–1992 in a former opencast mine in Northumberland, UK (1) found that cutting vegetation yearly after sowing seeds increased plant species richness compared to grazing with livestock after sowing. After one year, plant species richness did not differ significantly between areas where seeds were sown and then cut yearly (20 species/m2) and area where seeds were sown and grazed by livestock (21 species/m2). However, after two years, species richness was higher in areas that were cut annually, and this remained the case for the following two years (seeded and cut: 22–24 species/m2; seeded and grazed: 20–22 species/m2). In 1986, topsoil that had been removed during mining was replaced and sown with a temporary cover crop. The cover crop was removed by ploughing in autumn 1987 and soil disturbed using a power harrow in April 1988. Two 1,500 m2 plots were fenced and cut every year in mid-July, while two plots were grazed by livestock throughout the summer. All plots were grazed in spring. In July 1989–1992, vegetation cover for each species was estimated using fifteen 1-m2 quadrats in each plot.Study and other actions tested
A replicated, randomized, controlled study in 1986 in a former arable field in Sussex, UK (Hutchings & Booth 1996) found that cutting vegetation before sowing seeds increased the germination of four grassland plant species compared to sowing without cutting. The average percentage of seeds that germinated for four grassland plant species was higher in plots where vegetation was cut and seeds sown (5.8–21.0%) than in plots where seeds were sown but vegetation was not cut (0.1–1.8%). In April 1986, vegetation was cut to a height of 3 cm in twenty 7 x 5 m plots, and seeds were sown of either Achillea millefolium, Pimpinella saxifraga, Plantago media or Scabiosa columbaria (five plots sown/species). In twenty other plots, seeds were sown but vegetation was not cut. Plots were monitored for seed germination every 1–2 weeks until September 1986.Study and other actions tested
A replicated study in 1993–1999 in an ex-arable field near Aberdeen, Scotland, UK (Warren et al. 2002) found that cutting sown plots each year and removing cut vegetation led to a greater number, but lower cover, of sown grass and forb species compared to cutting and not removing cut vegetation. After six years, sown plots that were cut each year and had cuttings removed had on average more sown species (3.4 species/m2) than sown plots that were cut and had cuttings left in place (2.3 species/m2). However, plots with cuttings removed had lower cover of sown species (63%) than plots with cuttings left in place (76%). In April–May 1993, four 20 x 40 m fenced plots were ploughed and sown with a native seed mix (four grass and 10 forb species sown at a rate of 20 kg/ha). Each year in 1994–1999, all plots were cut in early August. Half of the plots had cuttings removed, while half had cuttings left in place. In 1994–1999, vegetation was monitored annually within 20 x 1 m2 quadrats (number of sown species) and 10 x 0.25 m2 quadrats (cover of sown species) randomly placed in each plot.Study and other actions tested
A replicated, randomized, paired, controlled study in 1998–1999 in a species-poor grassland in Göttingen, Germany (Hofmann & Isselstein 2004; same study site as Hofmann & Isselstein 2005) found that mowing more frequently after sowing seeds increased seedling survival for seven sown forb species. After 12 months, the average percentage of seedlings that survived for seven sown forb species was higher in plots mown once every 1–3 weeks (55–84%) than in plots mown once every nine weeks (10–51%). In July 1998, multiple 2 x 6 m plots (number not reported) were sown with seeds of seven local forb species and mown once every one, three or nine weeks for 12 months. Emergence and survival of seedlings was recorded by marking seedlings in 0.5 x 0.5 m subplots within each plot from April 1998 to July 1999.Study and other actions tested
A replicated, randomized, paired, controlled study in 1994–1996 in two ex-arable sites in Scotland, UK (Lawson et al. 2004) found that mowing after sowing seeds increased the abundance of sown forb species and the number of sown species when compared to areas that were seeded but not mown. The cover of sown forb species was higher in areas that had been sown with seeds and mown (10%) than areas that were sown with seeds but not mown (6%). The number of sown species was also higher in areas that were sown with seeds and mown (no data reported). Before seeding, both sites were ploughed and harrowed. In May 1994, seeds of 18 species were sown at a rate of 4 g/m2 in eight 3 x 9 m plots. Half of the area of these plots was mowed once or twice in 1994, while half remained unmown. Plant cover and species richness were estimated in June/July 1995 and 1996 using a 1 x 1 m quadrat placed in each plot.Study and other actions tested
A replicated, randomized, paired, controlled study in 1998–1999 in a species-poor grassland near Göttingen, Germany (Hofmann & Isselstein 2005; same study site as Hofmann & Isselstein 2004) found that mowing more frequently after sowing seeds increased the abundance of five of seven sown forb species. After 12 months, five of seven sown forb species were more abundant in areas that were mown once/week than areas mown once every nine weeks: autumn hawkbit Leontodon autumnalis (16–36 vs 4–6 plants/m2 respectively), ribwort plantain Plantago lanceolata (4–19 vs 1 plant/m2), goatsbeard Tragopogon pratensis (8–19 vs 3–7 plants/m2), common bird's-foot trefoil Lotus corniculatus (4–9 vs 1–4 plants/m2), red clover Trifolium pratense (3–11 vs 0–4 plants/m2). For the two other species, there was no significant difference in the number of plants in areas mown once/week or once every nine weeks: wild carrot Daucus carota (5–8 vs 4–8 plants/m2), brown knapweed Centaurea jacea (13–30 vs 8–16 plants/m2). In July 1998, eight 2 x 2 m plots were sown with seeds of seven local grassland forb species. In 1998 and 1999, four of the plots were mown once/week, and four plots were mown once every nine weeks. In July 1999, the number of plants of each species was counted in each plot.Study and other actions tested
A replicated, controlled study in 2002–2004 in seven grassland sites in northern Germany (Rasran et al. 2007) found that mowing after sowing and planting led to an increased number of ragged robin Silene flos-cuculi and marsh birdsfoot trefoil Lotus pedunculatus seedlings and a greater biomass of transplants at less than half of the sites. After two years, the average number of sown ragged robin seedlings was higher in mown plots (2–5 seedlings/plot) than unmown plots (0–3 seedlings/plot) at two of seven sites. The same was true for marsh birdsfoot trefoil seedlings at one of seven sites (data not reported). After one year, the average biomass of ragged robin and marsh birdsfoot trefoil transplants was higher in mown than unmown plots at three of seven and two of seven sites, respectively (data not reported). There were no significant differences at the other sites. Two plots (1 x 2 m) within each of six blocks were established at each of seven fen-grassland sites. Two hundred ragged robin and marsh birdsfoot trefoil seeds were sown within an area (0.25 x 0.25 m) in each plot in autumn 2002. Four equal-sized juvenile plants of each species were transplanted to each plot in April 2003. One plot/block was mown in June 2003 and 2004, the other was left unmown. Vegetation in each plot was monitored at the end of summer in 2003 and 2004. Biomass was sampled in August 2004.Study and other actions tested
A replicated, randomized, paired, controlled study in 2005–2006 in a degraded steppe grassland in Hebei province, northern China (Liu et al. 2008) found that cutting grass after sowing seeds did not alter the emergence rate of plants, their survival, or seedling density compared to sowing and not cutting. The percentage of seeds from which plants emerged did not significantly differ between areas that were cut after seeding (48%) and areas that were not cut after seeding (48%). Similarly, there was no significant difference for seedling survival after one year (cut: 3.0%; uncut: 3.5%) or seedling density after one year (cut: 5.6 seedlings/m2; uncut: 11.0 seedlings/m2). Seeds were collected in Saibei administrative region in autumn 2004. In June 2005, seeds were sown in all plots at a density of 400–1200 seeds/m2 and soil compressed using a roller. In half of all plots, vegetation was cut to a height of 5 – 10 cm (replication of experiment unclear). Plots were fenced to prevent damage from livestock and sprayed with pesticides. Seedling density and survival was monitored between June 2005 and August 2006. This study was also part of an experiment testing the effects of fertilizer addition and soil disturbance on seedling performance.Study and other actions tested
A replicated, site comparison study in 2006–2008 in 10 former arable fields and six natural grasslands in Hungary (Török et al. 2010) found that annual mowing after sowing grassland species increased plant community similarity to that of natural grassland. No statistical analyses were carried out in this study. After three years, the plant communities in areas that were sown with seeds and subsequently mowed were more similar to those of natural grasslands than after one year (data presented as graphical analysis). In 2006, ten fields were ploughed. Six fields were sown with seeds of Festuca rupicola, Poa angustifolia, and Bromus inermis and four fields were sown with seeds of P. angustifolia and Festuca pseudovina at a rate of 25 kg/ha. The fields were mowed in June 2007 and 2008. In each field, and six nearby intact loess and alkali grasslands four 1-m2 plots were used to measure cover of plant species in June 2006–2008.Study and other actions tested
A replicated, controlled study in 2011–2012 in a species-poor hay meadow in Germany (John et al. 2016) found that cutting vegetation three times/year after sowing seeds resulted in more species characteristic of hay meadows than cutting once/year after sowing seeds. After one year, the number of species characteristic of hay meadows was higher in areas where seeds were sown and vegetation was cut three times/year (4.5 species/plot) than in areas where seeds were sown and vegetation was cut once/year (3.2 species/plot). In September 2011, four blocks consisting of twelve 4 × 4 m plots were established. All plots were ploughed and vegetation removed, following which they were sown with the seeds of 18 plant species. In each block, vegetation was cut three times/year in six plots and once/year in six other plots. Vegetation cover in a 0.5 × 0.5 m quadrat in each plot was surveyed in autumn 2012.Study and other actions tested