Action

Sow seeds of parasitic species (e.g. yellow rattle)

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Six studies examined the effects of sowing seeds of parasitic species on grassland vegetation. Four studies were in the UK, one study was in Switzerland and one was in Belgium.

VEGETATION COMMUNITY (6 STUDIES)

VEGETATION ABUNDANCE (3 STUDIES)

  • Overall abundance (1 study): One review in the UK found that sowing seeds of the parasitic plant yellow rattle led to a decrease in total plant biomass in three of four studies.
  • Characteristic plant abundance (1 study): One controlled study in Belgium found that sowing seeds of the parasitic plant marsh lousewort increased the abundance of six target plant species.
  • Grass abundance (1 study): One replicated, controlled study in Switzerland found that sowing seeds of the parasitic plant European yellow rattle led to a decrease in grass cover.
  • Forb abundance (1 study): One replicated, controlled study in Switzerland found that sowing seeds of the parasitic plant European yellow rattle did not alter the cover of forbs.

VEGETATION STRUCTURE (0 STUDIES)

About key messages

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

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

Supporting evidence from individual studies

  1. A replicated, controlled study in 1995–1997 in a former arable field in Lupsingen, Switzerland (Joshi et al. 2000) found that sowing seeds of the parasitic plant European yellow rattle Rhinanthus alectorolophus led to an increase in plant species diversity and a decrease in grass cover but did not alter the cover of forbs. After one year, quadrats sown with yellow rattle seeds had on average a greater diversity of plant species than quadrats not sown with yellow rattle seeds (data reported as evenness index). Average grass cover was lower in quadrats sown with yellow rattle (40%) compared to unsown quadrats (51%), whereas there was no significant difference in the cover of forbs (herbs: 34% vs 26%; legumes: 23% vs 26%). In May 1995, two replicate blocks each consisting of 32 plots (8 x 2 m) were sown with different assemblages of local grassland seeds. In October 1996, yellow rattle seeds were sown at a rate of 800 seeds/m2 within a 50 x 50 cm quadrat within each plot, while a second quadrat was left unsown. All plots were mown twice/year. In September 1997, vegetation was assessed in each of the two quadrats/plot.

    Study and other actions tested
  2. A replicated, randomized, paired, controlled study in 1998–2002 in improved grassland in Oxfordshire, UK (Pywell et al. 2004) found that sowing seeds of the parasitic plant yellow rattle Rhinanthus minor along with seeds of grassland forbs increased plant species richness. Species richness was higher in areas where yellow rattle had been sown with seeds of other plants (4.2–5.8 species/plot) than in areas where no seeds of yellow rattle were sown (1.4–1.8 species/plot). In December 1998, five blocks each with four 10 × 10 m plots were established, and livestock allowed to graze the site after which they were removed. In three plots in each block, yellow rattle seeds were sown at a rate of 0.1–2.5 kg/ha, while in one plot no yellow rattle seeds were sown. In October 2000, seeds of 10 forb species were sown in all plots at a rate of 5 kg/ha. Hay was cut every year in July and the field was grazed in autumn by cattle or sheep at a rate of 35–50 animals/ha. In June 2001 and 2002, vegetation was surveyed using seven to ten 1 × 1 m quadrats/plot.

    Study and other actions tested
  3. A review in 2005 of four grassland restoration studies in England, UK (Bullock & Pywell 2005) found that sowing seeds of the parasitic plant yellow rattle Rhinanthus minor led to an increase in plant species richness in all of three studies and a decrease in total plant biomass in three of four studies. Three studies found that after 1–4 years, species richness increased in sites sown with yellow rattle for target plants (by 60%; one study), forb species (by 45%; one study) or plants overall (one additional species; one study) compared to sites not sown with yellow rattle. Three of four studies found that after 1–2 years, total plant biomass decreased by 21–44% in sites sown with yellow rattle compared to unsown sites, whereas one study found no significant difference. Four restoration studies were carried out in former arable fields or species-poor grasslands. In each study, yellow rattle seeds were sown in part of the site at a rate of 12–1,000 seeds/m2, while another part was left unsown. Vegetation was assessed (species richness in three studies, biomass in all four studies) during 1–4 years after sowing. One study has been summarised individually (2).

    Study and other actions tested
  4. A replicated, controlled study in 1998–2000 at a grassland site in West Yorkshire, UK (Westbury et al. 2006) found that sowing seeds of the parasitic plant yellow rattle Rhinanthus minor increased plant species richness and diversity. After one year, plots sown with yellow rattle prior to a grassland seed mix had on average a greater number of sown species (4–8.4), unsown species (8.7–11.4) and greater overall plant diversity (data reported as Shannon diversity index) than plots not sown with yellow rattle prior to a grassland seed mix (sown species: 2.7–5.4; unsown species: 7–9.7). In autumn 1998, six plots (each 4 x 4 m) were created on a newly established meadow. Three plots were sown with yellow rattle seeds (1,000 seeds/m2), and three plots were left unsown. In April 1999, all six plots were sown with a commercial seed mix of six grass and six forb species at a rate of 30 kg/ha. All plots were cut in July each year. In May 1999 and 2000, vegetation was recorded within three randomly placed 50 x 50 cm quadrats/plot.

    Study and other actions tested
  5. A replicated, randomized, paired controlled study in 1999–2003 in two species-poor grassland sites in the UK (Pywell et al. 2007) found that disturbing soil and sowing seeds of the parasitic plant yellow rattle Rhinanthus minor did not alter the number of plant species compared to disturbing soil alone. In each of four years, plant species richness did not significantly differ between areas where soil was disturbed and yellow rattle seeds were sown (9.1–16.0 species/plot) and areas where soil was disturbed but seeds were not sown (11.0–16.2 species/plot). In September 1999, in eight 15 x 15 m plots at each site, soil was disturbed using a power-harrow to a depth of 5 cm and seeds of the plant yellow rattle were sown at a rate of 2.4 kg/ha. In eight other plots, soil was disturbed but no seeds were sown. All plots were paired. Vegetation composition was recorded in June 1999–2003 using five randomly placed 1 x 1 m quadrats/plot.

    Study and other actions tested
  6. A controlled study in 1994–2000 in a degraded fen meadow in Oostkamp, Belgium (Decleer et al. 2013) found that sowing seeds of the parasitic plant marsh lousewort Pedicularis palustris increased overall plant species richness and the abundance of six target plant species. After six years, the average number of plant species was higher in the site where lousewort seeds were sown (21 species/quadrat) than the site where no lousewort seeds were sown (14 species/quadrat). The site sown with lousewort also had a greater abundance of six target plant species (45–191 plants/10 m2) than the unsown site (2–74 plants/10 m2; see original paper for details). In July 1994, two adjacent sites measuring 20 x 20 m were established in a fen meadow dominated by acute sedge Carex acuta. Marsh lousewort was sown in one site (500 seeds), whereas no seeds were sown in the other. Both sites were mowed 1–2 times/year. Marsh lousewort detected in the unsown site was manually removed. In July 2000, vegetation was surveyed within 10 randomly selected 1-m2 quadrats/site.

    Study and other actions tested
Please cite as:

Martin, P.A., Ockendon, N., Berthinussen, A, Smith, R.K. and Sutherland W.J. (2021) Grassland Conservation: Global evidence for the effects of selected interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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Grassland Conservation

This Action forms part of the Action Synopsis:

Grassland Conservation
Grassland Conservation

Grassland Conservation - Published 2021

Grassland Synopsis

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