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Providing evidence to improve practice

Action: Add mosses to peatland surface Peatland Conservation

Key messages

  • Thirteen studies evaluated the effects of adding mosses or moss fragments onto peatland surfaces. Eleven were in bogs and two in were in fens. One study was a continuation of an earlier study. Three of the studies involved sowing moss in gel beads.
  • Sphagnum moss cover (12 studies): Eleven studies in bogs in the UK, Canada, Finland and Germany and fens the USA reported that Sphagnum moss was present, after 1–4 growing seasons, in at least some plots sown with Sphagnum. Cover ranged from negligible to >90%. Six of these studies were controlled and found that Sphagnum cover or abundance was higher in sown than unsown plots. One of the studies reported that Sphagnum only survived in one of three sites, and only when plots were mulched. One additional study in Canada found that adding Sphagnum to bog pools did not affect Sphagnum
  • Other moss cover (4 studies): Four studies (including one replicated, randomized, paired, controlled, before-and-after) in bogs in Canada and fens in Sweden and the USA reported that mosses or bryophytes other than Sphagnum were present, after 2–3 growing seasons, in at least some plots sown with moss fragments. Cover ranged from negligible to 76%. In the fens in Sweden and the USA, moss cover was low (<1%) unless the plots were mulched, shaded or limed.

Supporting evidence from individual studies

1 

A before-and-after study in 1991–1993 in a historically mined raised bog in England, UK (Money 1995) reported that most Sphagnum moss species did not survive when sown onto peat or into pools, but that the surviving species typically spread. Of eight Sphagnum species spread onto bare peat, only one survived after 30 months: feathery bog moss Sphagnum cuspidatum. There were 20 plants/100 cm2. Of eight Sphagnum species spread onto floating rafts, three survived: feathery bog moss, recurved bog moss Sphagnum recurvum and lobed bog moss Sphagnum auriculatum. There were 25–40 plants/100 cm2. Two species had spread beyond the initial planted area. In May 1991, pairs of pools (4 m3) and bare peat plots (4 m2) were excavated (number of pools/plots not reported). Individual Sphagnum plants (5 cm long) were placed on the bare peat and on a floating mesh raft (50 plants in a 0.5 m2 area for each species). In November 1993, survival and density of each Sphagnum species were recorded.

2 

A replicated, randomized, paired, controlled, before-and-after study in 1993 in a historically mined raised bog in Quebec, Canada (Campeau & Rochefort 1996; part of 3) reported that plots sown with Sphagnum moss fragments developed some Sphagnum cover. Before sowing, plots were bare peat. After one growing season, sown plots had 1–7% Sphagnum cover. There were also more Sphagnum shoots after one growing season (180–860/m2) than the number introduced (150–450/m2). Additionally, cover was significantly higher in plots sown at higher densities (low initial density: 1–2%; medium: 2–4%; high: 3–7% final cover) and differed between species (see original paper). The size of introduced fragments had no effect on cover (data not reported). In June 1993, twenty 10 m2 plots were established on bare rewetted peat. Sixteen plots were sown with a single Sphagnum species (four plots x four species) and four plots sown with a mixture of all four species. Within each plot, three fragment densities (low: 150; medium: 300; high: 450/m2) and two fragment sizes (1 or 2 cm) were applied to six subplots. Additional subplots were left unsown as controls, but data were not reported. All plots were shaded with a plastic cloth. In October 1993, Sphagnum cover was visually estimated and live shoots counted in four 25 x 25 cm quadrats/subplot.

3 

A replicated, randomized, paired, controlled, before-and-after study in 1993–1995 in a historically mined raised bog in Quebec, Canada (Rochefort et al. 2003) reported that plots sown with Sphagnum mosses had greater Sphagnum cover, over three growing seasons, than unsown plots. Sphagnum cover was 1–5% in sown plots but <0.5% in unsown plots. Amongst sown plots, Sphagnum was still present after the third, driest growing season. However, cover had dropped to 1–3%. These results were not based on tests of statistical significance. Sphagnum cover was significantly higher in plots sown at higher densities (low initial density: 1%; medium: 2%; high: 3% final cover) but was not affected by the size of introduced fragments (data not reported). In June 1993, twenty 10 m2 plots were established on rewetted bare peat. In each plot, six subplots were sown with Sphagnum moss fragments whilst two subplots were not sown. Amongst the sown subplots, three fragment densities (low: 150; medium: 300; high: 450/m2) and two fragment sizes (1 or 2 cm) were applied. All plots were shaded with a plastic cloth. In October 1993, Sphagnum cover was estimated and live shoots counted in four 25 x 25 cm quadrats/subplot.

4 

A replicated before-and-after study in 1994–1998 in a historically mined bog in Finland (Tuittila et al. 2004) reported that plots sown with fragments of fine bog moss Sphagnum angustifolium (after rewetting) developed cover of fine bog moss. Before sowing, plots were bare peat. After four years, fine bog moss cover was 29%. In the previous three years, fine bog moss cover varied between 16 and 26%. In September 1994, 2–3 cm fragments of fine bog moss were spread on six 60 x 60 cm plots, forming a covering layer. The bare peat plots had been rewetted earlier in 1994. The moss was collected from a nearby pristine bog. Every August from 1995 to 1998, Sphagnum cover was measured in one 30 cm2 quadrat/plot.

5 

A replicated, controlled, before-and-after study in 1999–2003 in a historically mined bog in eastern Canada (Mazerolle et al. 2006) found that sowing Sphagnum moss (and herbs) into created pools did not significantly affect vegetation cover. After four years, planted and unplanted pools had similar cover of Sphagnum (13 vs 9%), other mosses (3 vs 3%), herbs (3 vs 5%) and shrubs (6 vs 5%). In 1999, eight 6 x 8.5 m pools were created by excavating and rewetting a bog (blocking ditches and building embankments). In 2000, four pools were sown with Sphagnum moss (introduced to the water column). Four herb species were also planted in and around these pools. The other four pools were not planted, although bog vegetation fragments were spread onto the rest of the peatland (see intervention Spread mixed vegetation onto peatland surface). In 2003, vegetation cover was recorded in 36 quadrats/pool, each 30 x 30 cm, along six bank-to-bank transects.

6 

A replicated before-and-after study in 2004–2005 in a degraded fen in Sweden (Mälson & Rydin 2007) reported that four sown fen-characteristic moss species had variable survival after one growing season, and developed variable cover after two growing seasons. Before sowing, plots were bare peat. One growing season after sowing, 4–93% of moss fragments had survived. Two growing seasons after planting, cover of fen-characteristic mosses was <1–34%. Additionally, survival and cover were significantly higher in limed than unlimed plots (see intervention Add lime before/after planting) and in plots covered with mulch or plastic gauze than uncovered plots (see intervention Cover peatland after planting). In June 2004, fragments of four fen-characteristic moss species were added to 24 plots (625 cm2) of bare rewetted peat: two scorpion mosses Scorpidium spp., three-ranked spear moss Pseudocalliergon trifarium, and starry feather moss Campylium stellatum. Each species was sown in separate 9 cm2 subplots (number not reported; density 16 fragments/subplot). Twelve plots were also limed and eight were covered (with sedge litter or plastic gauze). After one growing season, moss survival was assessed in each subplot. After two growing seasons, moss cover was visually estimated.

7 

A replicated, before-and-after study in 2007–2010 in three degraded fens in Colorado, USA (Chimner 2011) reported that mosses established in 4 of 12 plots sown with moss fragments, and only when mulched. Before sowing, plots were bare peat. After three years, no moss survived on six plots without mulch. Under mulch, Russow’s bog moss Sphagnum russowii survived in one of three sites (reaching 19% cover) and haircap moss Polytrichum strictum survived in all three sites (reaching 3–11% cover). In July 2007, moss fragments (<1 cm length) were spread onto twelve bare peat plots in each fen. Moss was a mixture of three Sphagnum species and haircap moss. Of the twelve plots, six were mulched with straw (immediately) and shredded aspen (after one year). In summer 2010, moss cover was measured using a pin-drop quadrat.

8 

A replicated, randomized, paired, controlled, before-and-after study in 2007–2010 in two historically disturbed bogs in Ontario, Canada (Corson & Campbell 2013) found that plots sown with Sphagnum moss fragments had greater bryophyte cover, after three years, than unsown plots. This was true for both Sphagnum moss cover (sown: 38–52%; unsown: 8%) and total bryophyte cover (sown: 66–76%; unsown: 26%). Amongst sown plots, bryophyte cover did not significantly differ between plots with and without mulch (see intervention Add mulch after planting), nurse plants (see intervention Introduce nurse plants before planting peatland vegetation) or peat blocks for shelter (see intervention Create mounds or hollows before planting). In August 2007, forty-eight 2 x 2 m plots were established, in six blocks of eight, across two bogs. Plots were initially bare peat, following disturbance from vehicles or pipeline construction. Forty-two plots (seven random plots/block) were sown with fresh moss fragments (mix of rusty bog moss Sphagnum fuscum and flat-topped bog moss Sphagnum fallax). The remaining six plots (one plot/block) were not sown. All plots received 30 g/m2 rock phosphate fertilizer. Some sown plots were also mulched, sheltered with peat blocks or planted with nurse plants. In August 2010, moss cover was visually estimated in six 12.5 x 12.5 cm quadrats/plot.

9 

A replicated, controlled, before-and-after study in 2007–2010 in two historically disturbed bogs in Ontario, Canada (Corson & Campbell 2013) found that plots sown with Sphagnum moss fragments had greater bryophyte cover, after three years, than unsown plots. This was true for both Sphagnum moss cover (sown: 5–17%; unsown: 1%) and total bryophyte cover (sown: 24–51%; unsown: 21%). Adding mulch did not significantly affect bryophyte cover (see intervention Add mulch after planting). In May 2007, twenty-four 1 m2 plots of bare peat were sown with moss fragments (a mix of rusty bog moss Sphagnum fuscum and flat-topped bog moss Sphagnum fallax, stored outside during the preceding winter). Twelve of the plots were also mulched with straw. Some additional control plots (number not reported) were neither sown nor mulched. All plots received 30 g/m2 rock phosphate fertilizer. In August 2010, moss cover was visually estimated in six 12.5 x 12.5 cm quadrats/plot.

10 

A replicated before-and-after study in 2004–2009 and 2011–2013 in two bogs in Germany (Gaudig et al. 2013) reported that plots sown with Sphagnum moss fragments (then mulched) developed high Sphagnum cover. Before sowing, plots were bare peat. In one bog (Ramsloh), papillose bog moss Sphagnum papillosum reached 92% cover four years after spreading. In the other bog (Rastede), blunt-leaved bog moss Sphagnum palustre had reached 97% cover and papillose bog moss 91% cover two years after initial spreading. In 2004 (Ramsloh) and 2011 (Rastede), fragments of single moss species were spread onto 60–224 bare peat plots (15 x 15 or 25 x 25 cm). At Rastede, gaps were filled with additional fragments one year later. All plots were mulched with straw and a high water table was maintained. Sphagnum cover was estimated in each plot 1–3 times/year.

11 

A replicated, paired, controlled, before-and-after study in 2010–2013 in a blanket bog in England, UK (Rosenburgh 2015) reported that Sphagnum moss established in 4 of 12 sown plots, mainly when bare fragments (rather than fragments in gel beads) were sown into existing vegetation (rather than onto bare peat). Before sowing, no Sphagnum was present. Of six grassy plots sown with Sphagnum, four contained the sown species after three years: three sown with bare Sphagnum fragments (251–450 Sphagnum clumps surviving; negligible cover) and one sown with Sphagnum in gel beads (two Sphagnum clumps surviving; negligible cover). Of six bare peat plots sown with Sphagnum, none contained the sown species after three years. Of 12 unsown control plots, nine contained no Sphagnum after three years but three, on grassy vegetation, contained 1–67 clumps. In May 2010, eighteen 25 m2 plots were established: three blocks of three on restored grassy vegetation, and three blocks of three on bare peat. In each block, one plot was sown with bare Sphagnum fragments (<1 cm thick layer), one was sown with Sphagnum fragments in gel beads (400 beads/m2) and one was not sown. However, all of these plots were mulched (with heather Calluna vulgaris brash). In August 2013, Sphagnum clumps were identified in each plot and their area was measured.

12 

A replicated, paired, controlled study in 2009–2013 in a blanket bog in England, UK (Rosenburgh 2015) reported that Sphagnum moss established in 22 of 162 plots sown with moss/gel beads, but mainly when sown into existing vegetation (rather than onto bare peat). No statistical tests were carried out. After 1–3 years, Sphagnum clumps were present in 22 of 162 sown plots (1–288 clumps/plot or 0.06–18% of the number of beads sown). The survival rate was higher in plots with existing vegetation (natural: clumps present in 24% of sown plots; restored: clumps present in 15% of sown plots) than in bare peat plots (clumps present in 4% of sown plots). Forty adjacent unsown plots did not contain any Sphagnum. Between 2009 and 2012, gel beads containing Sphagnum fragments were sown onto a bog (4 m2 plots; 400 beads/m2). There were 1–3 plots for each combination of Sphagnum species (six options), sowing date (six options) and existing vegetation (three options: natural; restored grassy vegetation; bare peat). For each sowing date and vegetation type, some additional plots were left unsown. In August 2013, Sphagnum clumps were identified in each plot.

13 

A replicated, paired, controlled study in 2010–2013 in a degraded, grassy blanket bog in England, UK (Rosenburgh 2015) reported that Sphagnum moss was present in 11 of 12 plots sown with moss/gel beads, but that cover was low. After three years, the 11 plots contained 4–98 discrete clumps of Sphagnum (0.25–6% of the number of beads sown). Sphagnum cover was <1% in all plots. Adjacent unsown plots did not contain any Sphagnum. In October 2010, fifteen 4 m2 plots were established (in three blocks of five) on a degraded blanket bog dominated by purple moor grass Molinia caerulea. For each of four Sphagnum species, three plots (one plot/block) were sown with moss fragments encapsulated in gel beads (400 beads/m2). The remaining three plots (one plot/block) were not sown. In all plots, grass was cut before sowing (litter left in place). In September 2013, Sphagnum clumps were identified in each plot and their area was measured.

Referenced papers

Please cite as:

Taylor N.G., Grillas P. & Sutherland W.J. (2018) Peatland Conservation. Pages 329-392 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2018. Open Book Publishers, Cambridge, UK.