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Providing evidence to improve practice

Action: Cover peatland with organic mulch (without planting) Peatland Conservation

Key messages

Read our guidance on Key messages before continuing

  • Two studies evaluated the effects, on peatland vegetation, of covering a peatland with organic mulch (without planting). Both studies were in bogs (but in one study, being restored as a fen).
  • Vegetation cover (2 studies): One replicated, randomized, paired, controlled, before-and-after study in a bog in Canada found that covering bare peat with straw mulch did not affect cover of fen-characteristic plants. One replicated, controlled, before-and-after study in a bog in Australia reported that plots mulched with straw had similar Sphagnum moss cover to unmulched plots.
  • Characteristic plants (1 study): One replicated, randomized, paired, controlled, before-and-after study in a bog in Canada found that covering bare peat with straw mulch increased the number of fen characteristic plants present, but did not affect their cover.

Supporting evidence from individual studies


A replicated, randomized, paired, controlled, before-and-after study in 2001–2002 in a historically mined bog in Quebec, Canada (Cobbaert et al. 2004) found that mulching with straw increased the number of fen-characteristic plant species but had no effect on fen-characteristic plant cover. Note that the aim of this study was to create a fen, as the post-mining peat chemistry was more like a fen than a bog. Before sowing, no vegetation was present. After two growing seasons, there were more plant species typical of local fens in mulched plots (8 species) than unmulched plots (5 species). Fen plant cover did not significantly differ between mulched (6%) and unmulched plots (10%). In spring 2001, eighteen 5 x 5 m plots were established, in three blocks of six. Nine plots (three random plots/block) were mulched with straw (1,500 kg/ha). The other plots were not mulched. All plots had previously been rewetted, raked and fertilised. None of these plots were sown. In August 2002, cover of every plant species was estimated in ten 30 x 30 cm quadrats/plot.


A replicated, controlled, before-and-after study in 2003–2007 in a fire-damaged bog in Australia (Whinam et al. 2010) reported that mulching with straw had no effect on Sphagnum moss cover. This result is not based on a test of statistical significance. After 40 months, Sphagnum cover was similar in straw-mulched (8.6%) and unmulched plots (7.8%). This followed fluctuations over the 40 months, when Sphagnum cover was sometimes higher in mulched than unmulched plots but sometimes lower. Immediately before shading, plots had approximately 3% Sphagnum cover. In January 2003, the focal bog was burned by a wild fire. In October 2003, five burned plots (3 x 15 m) were mulched with sterilized straw (2 tonnes/ha). Five additional plots were not mulched. Vegetation cover was recorded in 0.25 m2 quadrats: five across the bog in October 2003, then one/plot every six months until March 2007.

Referenced papers

Please cite as:

Taylor N.G., Grillas P. & Sutherland W.J. (2019) Peatland Conservation. Pages 375-438 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.