Action

Use cutting/mowing to control problematic herbaceous plants

How is the evidence assessed?
  • Effectiveness
    40%
  • Certainty
    35%
  • Harms
    10%

Study locations

Key messages

  • Four studies evaluated the effects on peatland vegetation of cutting/mowing problematic herbaceous plants. Three studies were in fens or fen meadows and one was in a bogN.B. Cutting/mowing in historically disturbed peatlands is considered as a separate action.
  • Plant community composition (3 studies): Two replicated, randomized, paired, controlled, before-and-after studies in rich fens in Sweden found that mowing typically had no significant effect on the overall plant community composition. One controlled study in a fen meadow in the UK reported that mown plots developed different plant communities to unmown plots.
  • Characteristic plants (1 study): One replicated, randomized, paired, controlled, before-and-after study in a fen in Sweden found that mown plots contained more fen-characteristic plant species than unmown plots, although their cover did not differ significantly between treatments.
  • Vegetation cover (2 studies): Of two replicated, randomized, paired, controlled, before-and-after studies in rich fens in Sweden, one found that mowing had no effect on vascular plant or bryophyte cover over five years. The other reported that mowing typically increased Sphagnum moss cover and reduced purple moor grass cover, but had mixed effects on cover of other plant species.
  • Growth (1 study): One replicated, controlled, before-and-after study in a bog in Estonia found that clipping competing vegetation did not affect Sphagnum moss growth.

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 controlled study in 1927–1940 in a fen meadow in England, UK (Godwin 1941) reported that repeated cutting changed the composition of the plant community. These results were not tested for statistical significance. After 12 years, a plot cut every year had a plant community dominated by purple moor grass Molinia caerulea with abundant carnation sedge Carex panicea (data reported as abundance categories). Sawtooth sedge Cladium mariscus biomass decreased over time (from 490 g/m2 after one cut to 50 g/m2 after 12 cuts). In an uncut plot, sawtooth sedge remained the most abundant plant species (data reported as abundance categories). Additional plots cut every two, three or four years developed plant communities intermediate between the annually cut and uncut plots. In 1927, five 20 x 20 m plots were established in a fen meadow dominated by sawtooth sedge. Four plots were scythed in October: one every year, one every two years, one every three years and one every four years. Cuttings were removed. The other plot was left uncut. Vegetation cover was visually estimated in 1940. Above-ground vegetation biomass was estimated every year, by drying and weighing cuttings from 1 m2 of each plot.

    Study and other actions tested
  2. A replicated, controlled, before-and-after study in 2003–2006 in a raised bog in Estonia (Robroek et al. 2009) found that clipping competing plants did not significantly affect growth of Magellan’s bog moss Sphagnum magellanicum (data not reported). In six plots dominated by Magellan’s bog moss, vascular plants were clipped flush to the moss surface every May and September. Plants were not clipped in the six other plots. The height increase of Magellan’s bog moss was measured each summer.

    Study and other actions tested
  3. A replicated, randomized, paired, controlled, before-and-after study in 2002–2005 in two degraded rich fens in Sweden (Mälson et al. 2010) reported that repeated mowing altered the plant community composition, reduced cover of purple moor grass Molinia caerulea and increased overall cover of Sphagnum moss. The cover results were not tested for statistical significance. Mowing altered the development of the overall plant community over three years, although only significantly so in one fen (data reported as a graphical analysis). In three of four comparisons, mown plots had lower cover than unmown plots of purple moor grass (mown: 1–37%; not mown: 2–50%) but higher overall cover of Sphagnum moss (mown: 2–41%; not mown: 1–28%). However, cover of individual Sphagnum species showed mixed responses to mowing amongst sites or other treatments applied to plots. The same was true for sedges Carex spp., common cottongrass Eriophorum angustifolium and common reed Phragmites australis. In autumn 2002, sixty-four 2.5 x 2.5 m plots were established (in four blocks of 16) across two degraded fens. Thirty-two plots (eight random plots/block) were mown every autumn between 2003 and 2005. Cuttings were removed. The other plots were not mown. Additionally, trees had been removed from all plots and some plots had been rewetted or dug over. In 2002 (before intervention) and 2005, cover of every plant species was estimated in one 0.25 m2 quadrat/plot.

    Study and other actions tested
  4. A replicated, randomized, paired, controlled, before-and-after study in 1996–2001 in a degraded rich fen in Sweden (Sundberg 2011) found that mown and unmown plots maintained a similar overall plant community and vegetation cover, but that mown plots developed greater plant species richness. The overall plant community composition changed over five years, but in a similar way in mown and unmown plots (data reported as a graphical analysis). Likewise, vegetation cover increased by similar amounts, from similar initial values, in mown and unmown plots. This was true for vascular plants, fen-characteristic plants, bryophytes, six of eight Carex sedge species, common cottongrass Eriophorum angustifolium, purple moor grass Molinia arundinacea and common reed Phragmites australis. After five years, mown plots contained more vascular plant species than unmown plots (26 vs 18 species/m2) and more fen-characteristic plant species (14 vs 10 species/m2). Before mowing, species richness was similar in all plots (vascular: 15; fen-characteristic: 7–8). In 1996, nine pairs of 9 m2 plots were established in a degraded fen. Every August until 2001 vegetation was cut by hand (and cuttings removed) in one random plot/pair. The other plots were not cut. All plots had been cleared of trees and shrubs and were grazed every summer (approximately 50 cows/ha). In 1996 (before mowing) and 2001, cover of every plant species was estimated in one 1 m2 quadrat/plot.

    Study and other actions tested
Please cite as:

Taylor, N.G., Grillas, P. & Sutherland, W.J. (2020) Peatland Conservation. Pages 367-430 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Peatland Conservation

This Action forms part of the Action Synopsis:

Peatland Conservation
Peatland Conservation

Peatland Conservation - Published 2018

Peatland Conservation

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust