Providing evidence to improve practice

Action: Add mixed vegetation to peatland surface Peatland Conservation

Key messages

  • Eighteen studies examined the effect on peatland vegetation of spreading mixed vegetation onto the peatland surface. All 18 studies were in bogs (two being restored as fens). One study was a continuation of an earlier study.
  • Characteristic plants (1 study): One replicated, randomized, paired, controlled, before-and-after study in a degraded bog in Canada found that adding fen vegetation increased the number and cover of fen-characteristic plant species.
  • Sphagnum moss cover (17 studies): Seventeen replicated studies (five also randomized, paired, controlled, before-and-after) in bogs in Canada, the USA and Estonia reported that Sphagnum moss was present, after 1–6 growing seasons, in at least some plots sown with vegetation containing Sphagnum. Cover ranged from <1 to 73%. Six of the studies were controlled and found that Sphagnum cover was higher in sown than unsown plots. Five of the studies reported that Sphagnum cover was very low (<1%) unless plots were mulched after spreading fragments.
  • Other moss cover (8 studies): Eight replicated studies (seven before-and-after, one controlled) in bogs in Canada, the USA and Estonia reported that mosses or bryophytes other than Sphagnum were present, after 1–6 growing seasons, in at least some plots sown with mixed peatland vegetation. Cover was <1–65%.
  • Vascular plant cover (10 studies): Ten replicated studies in Canada, the USA and Estonia reported that vascular plants appeared following addition of mixed vegetation fragments to bogs. Two of the studies were controlled: one found that vascular plant cover was significantly higher in sown than unsown plots, but one found that sowing peatland vegetation did not affect herb cover.

Supporting evidence from individual studies

1 

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 7) found that plots sown with vegetation from the surface of a donor bog contained more Sphagnum moss shoots than plots sown with deeper material and unsown plots. Before sowing, plots were bare peat. After one growing season, plots sown with Sphagnum-dominated vegetation from a bog surface contained more live Sphagnum shoots (190–890/m2) than plots sown with material from 10–30 cm depth (10–100/m2) and plots that had not been sown (30–120/m2). Similar patterns were observed in a greenhouse experiment (see original paper). In June 1993, twelve blocks of four 1 m2 plots were established on bare rewetted peat. Within each block, three random plots were sown with vegetation or material from a nearby natural peatland: from the surface (top 10 cm), from 10–20 cm depth or from 20–30 cm depth. The vegetation was dominated by one of three Sphagnum moss species. The fourth plot was not sown. All plots were shaded with a plastic cloth. In October 1993, Sphagnum shoots were counted in four 25 x 25 cm quadrats/plot.

2 

A replicated before-and-after study in 1995 in a historically mined raised bog in Quebec, Canada (Bugnon et al. 1997) reported that plots sown with Sphagnum-dominated vegetation fragments (and mulched) developed Sphagnum moss cover. Before sowing, plots were bare rewetted peat. After one growing season, there were 146–629 Sphagnum shoots/m2. Additionally, shoot density was significantly higher in plots reprofiled into depressions before sowing (with plastic sheeting: 629 shoots/m2; without plastic sheeting: 469 shoots/m2) than in plots that remained at surface level (146 shoots/m2). In May 1995, three blocks of three 8 m2 plots were established on bare rewetted peat. Plots were sown with vegetation fragments (mostly seven mixed Sphagnum moss species) freshly collected from the surface of nearby bogs. In each block, one plot was flat and two were reprofiled to be lower in the centre. The slopes of one reprofiled plot/block were covered with plastic sheets. All plots were mulched with straw after sowing. In October 1995, Sphagnum shoots were counted in 240 quadrats/plot, each 400 cm2 and placed systematically.

3 

A replicated before-and-after study in 1993­­–1994 in a historically mined bog in Quebec, Canada (LaRose et al. 1997) reported that plots sown with Sphagnum-dominated vegetation fragments (after rewetting) developed some Sphagnum moss cover. Before sowing, plots were bare peat. After one year, Sphagnum cover was 3­­–6%. Between May and August 1993, vegetation fragments (mostly fine bog moss Sphagnum angustifolium and rusty bog moss Sphagnum fuscum) were scattered by hand onto three bare peat plots. The peat had been rewetted three months previously by digging water storage ditches. In September 1994, Sphagnum cover was estimated in 18 quadrats/plot, each 25 x 25 cm.

4 

A replicated before-and-after study in 1995–1996 in a historically mined raised bog in Quebec, Canada (Price et al. 1998) reported that plots sown with Sphagnum-dominated vegetation fragments (and mulched and/or roughened) developed some cover of mosses and vascular plants. Before sowing, plots were bare peat. After one year, Sphagnum cover was between 0.5 and 5%, other moss cover <1.5% and vascular plant cover <1.5%. Additionally, Sphagnum cover was significantly higher in plots mulched with straw (2–5%) than in unmulched plots (<0.5%) but was similar in roughened and smooth plots (<0.5–5% vs <0.5–2%). In May 1995, vegetation fragments (mostly Sphagnum moss) from the surface of a nearby bog were spread onto 24 rewetted bare peat plots (15 x 15 m). Twelve plots were also mulched with straw; twelve were not mulched. Eighteen plots had been roughened (by harrowing, ploughing or driving a bulldozer over); six were left smooth. In September 1996, vegetation cover was estimated in 36–72 quadrats/plot, each 25 x 25 cm.

5 

A replicated, randomized, paired, controlled, before-and-after study in 1993–1994 in a historically mined bog in Quebec, Canada (Rochefort & Bastien 1998) found that plots sown with Sphagnum-dominated vegetation fragments contained more Sphagnum moss shoots than unsown plots. This was true for all five focal Sphagnum species after one growing season (sown: 20–420; not sown: 17–90 shoots/m2) and after two growing seasons (sown: 65–450; not sown: 25–60 shoots/m2). These results are not based on tests of statistical significance. In spring 1993, fresh vegetation fragments (mostly Sphagnum moss) from the surface of a natural bog were added to slightly drained, bare peat plots (250 fragments/m2). Twelve plots were sown with fragments dominated by each of five Sphagnum species (one random plot in each of 12 blocks). Blocks grouped plots by moisture and cover treatment (none, polythene sheet or shade screen). Twelve control plots were not sown. In autumn 1993 and 1994, all Sphagnum shoots were counted in two 30 x 30 cm quadrats/plot.

6 

A replicated, randomized, paired, controlled, before-and-after study in 1993–1994 in a historically mined bog in Quebec, Canada (Rochefort & Bastien 1998) reported that plots sown with Sphagnum-dominated vegetation fragments typically contained more Sphagnum moss shoots, after two growing seasons, than unsown plots. These results are not based on tests of statistical significance. Plots sown with fragments dominated by fine bog moss Sphagnum angustifolium or Magellan’s bog moss Sphagnum magellanicum contained more Sphagnum shoots than unsown plots, whether irrigated or not (sown: 85–770; not sown: 50–80 shoots/m2). Plots sown with fragments dominated by rusty bog moss Sphagnum fuscum contained more Sphagnum shoots than unsown plots only when irrigated (sown: 95; not sown: 80 shoots/m2). Results after one growing season showed similar patterns. In spring 1993, fresh vegetation fragments (mostly Sphagnum moss) were added to slightly drained, bare peat plots (250 fragments/m2). Six plots received fragments dominated by each of three Sphagnum species (one random plot in each of six blocks). Six control plots received no fragments. Three blocks were irrigated. In autumn 1993 and 1994, all Sphagnum shoots were counted in ten 30 x 30 cm quadrats/plot.

7 

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; a continuation of 1) found that plots sown with vegetation from the surface of a donor bog contained more Sphagnum moss shoots, after 1–3 growing seasons, than plots sown with deeper material and unsown plots. Before sowing, plots were bare peat. After one to three growing seasons, plots sown with Sphagnum-dominated fragments from the surface of a donor bog contained more live Sphagnum shoots (190–1,240/m2) than plots sown with fragments from 10–30 cm depth (10–220/m2) or plots that had not been sown with any fragments (10–150/m2). In June 1993, twelve blocks of four 1 m2 plots were established on rewetted bare peat. Within each block, three random plots were sown with vegetation fragments (dominated by a single Sphagnum moss species) collected from a nearby natural peatland: from 0–10 cm depth (surface), 10–20 cm depth or 20–30 cm depth. No vegetation fragments were added to the fourth plot. All plots were shaded with a plastic cloth. In autumn 1993, 1994 and 1995, Sphagnum shoots were counted in four 25 x 25 cm quadrats/plot.

8 

A replicated before-and-after study in 1993–1999 in a historically mined bog in Quebec, Canada (Rochefort et al. 2003) reported that plots sown with vegetation fragments (and rewetted and mulched) developed cover of mosses and vascular plants. Before sowing, plots were bare peat. After six growing seasons, Sphagnum moss cover was 34–52%, other moss cover 2–5% and vascular plant cover 7–11%. Plots sown with a high density of fragments had greater Sphagnum cover (52%) than those sown with lower densities (34%). In winter 1993/1994, twelve 10 x 12 m plots were sown with material from the surface of a nearby bog: primarily a mixture of four Sphagnum species. Material was sown at high, medium or low density (ratio of source to recipient surface 1:10, 1:20 or 1:30) and as complete or mechanically shredded fragments. All plots were rewetted and harrowed before introduction of plant material and mulched with straw afterwards. Between 1995 and 1999, autumn vegetation cover was visually estimated along transects, in 28–36 quadrats/plot.

9 

A replicated before-and-after study in 1994–1996 in a historically mined bog in Quebec, Canada (Rochefort et al. 2003) reported that plots sown with vegetation fragments (some also mulched) developed some cover of mosses and vascular plants. No statistical tests were carried out. Before sowing, plots were bare peat. After three growing seasons, total vegetation cover was 3–24%. Sphagnum moss cover was <1–7%, other moss cover 1–13% and vascular plant cover 1–15%. Amongst all plots, Sphagnum formed a larger proportion of the moss cover in those mulched with straw (1–30%) than in unmulched plots (<1%). In early 1994, mixed plant material was collected from a natural bog and spread onto 12 pairs of plots (each 3 x 15 m), situated on bare rewetted peat. Then, one random plot in each pair was covered in straw mulch. In 1994 and 1996, vegetation cover was estimated within quadrats in each plot (details not reported).

10 

A replicated before-and-after study in 1994–1996 in a historically mined bog in Quebec, Canada (Rochefort et al. 2003) reported that plots sown with vegetation fragments (some also covered) developed cover of mosses and vascular plants. Before sowing, plots were bare peat. After three years, total vegetation cover was 3–20%. Sphagnum moss cover was <1–3%, other moss cover 2–16% and vascular plant cover <1%. Plots mulched with straw had significantly higher cover of all plant groups (except vascular plants) than plots shaded with a plastic screen, plots covered with shrub roots or unprotected control plots. Amongst these other treatments, vegetation cover was similar. In spring 1994, the moss layer was scraped from the surface of a natural bog and spread onto twelve 9 m2 bare peat plots. Three plots received each of the four cover treatments: straw, plastic, roots or none. In 1994 and 1996, vegetation cover was estimated in each plot (details not reported).

11 

A replicated before-and-after study in 1997–1999 in a historically mined bog in Minnesota, USA (Rochefort et al. 2003) reported that plots sown with vegetation fragments (some also mulched and/or planted with nurse plants) developed cover of mosses and vascular plants. Before sowing, plots were bare peat. After two growing seasons, total vegetation cover was 2–77%. Sphagnum moss cover was 0–73%, other moss cover 0–1% and vascular plant cover 1–3%. Plots mulched with straw had higher total vegetation and Sphagnum cover than unmulched plots, but similar cover of other mosses and vascular plants (see intervention Add mulch after planting). Plots planted with nurse sedges had similar cover of all vegetation groups to plots without nurse sedges (see intervention Introduce nurse plants before planting peatland vegetation). These results were not tested for statistical significance. In 1997–1998, vegetation was scraped from the surface of natural bogs and spread onto forty-eight bare peat plots (1.5 x 1.5 m), arranged in six blocks of eight. Four random plots/block were mulched with straw (3,000 kg/ha). Four random plots/block were also planted with sedges Carex oligosperma before adding vegetation fragments. In October 1999, vegetation cover was visually estimated in four 25 x 25 cm quadrats/plot.

12 

A replicated before-and-after study in 1993–1996 in a historically mined bog in Quebec, Canada (Rochefort et al. 2003) reported that plots sown with vegetation fragments (some also mulched) developed some cover of mosses and vascular plants. Before sowing, plots were bare peat. After three growing seasons, sown and mulched plots had 3–11% total vegetation cover, 1–4% Sphagnum moss cover, 2–6% other moss cover and 1–2% vascular plant cover. Sown plots that were not mulched had <2% vegetation cover (a mixture of Sphagnum, other moss and vascular plants). In autumn 1993, vegetation was scraped from the surface of a natural bog and spread onto a ploughed, bare peat site. Within this site, some 10 x 10 m plots were mulched with straw immediately or in the following spring (number of plots not reported). In autumn 1996, vegetation cover was visually estimated in fourteen 25 x 25 cm quadrats/plot.

13 

A replicated before-and-after study in 1996–1999 in a historically mined raised bog in Quebec, Canada (Campeau et al. 2004) reported that plots sown with Sphagnum-dominated vegetation fragments (then mulched) developed cover of Sphagnum and vascular plants. Before sowing, plots were bare peat. After four growing seasons, Sphagnum cover was 8–62% and vascular plant cover 5%. Additionally, plots reprofiled into basins before sowing had significantly greater Sphagnum cover (56–62%) than plots that remained at surface level (8–23%). Vascular plant cover did not differ between reprofiled and surface-level plots. In May 1996, freshly collected vegetation fragments (mostly Sphagnum moss) were sown onto eight 8 x 12 m plots. Four of these plots had been reprofiled (20–25 cm depth of peat pushed into ridges around the plot). Equally sized areas of each plot were sown with vegetation dominated by rusty bog moss Sphagnum fuscum, Magellanic bog moss Sphagnum magellanicum or red bog moss Sphagnum rubellum. All plots were mulched with straw after sowing. In autumn 1999, vegetation cover was estimated in 72 quadrats, each 25 x 25 cm, across each plot.

14 

A replicated before-and-after study in 1996–1999 in a historically mined raised bog in Quebec, Canada (Campeau et al. 2004) reported that plots sown with vegetation fragments (some also reprofiled) developed cover of mosses and vascular plants. Before sowing, plots were bare peat. After four growing seasons, Sphagnum moss cover was 17–52%, other moss cover 2% and vascular plant cover 2–4%. Plots that had been reprofiled into basins before sowing had significantly greater Sphagnum cover (41–52%) than plots that remained at surface level (17–19%), but similar cover of other mosses and vascular plants. In May 1996, freshly collected vegetation fragments were spread by hand onto 14 plots. The fragments were mainly rusty bog moss Sphagnum fuscum or red bog moss Sphagnum rubellum but contained seeds and fragments of other plants. Four plots (15 x 15 m) were at surface level, whilst ten plots had been reprofiled into depressions (4–20 m wide) bordered by peat ridges (30–60 cm high). All plots were mulched with straw after sowing. In autumn 1998, vegetation cover was visually estimated in 12–30 quadrats, each 25 x 25 cm, across each plot.

15 

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 plots spread with peat and vegetation from donor fens developed greater cover and richness of fen-characteristic plant species than plots without added material. Before intervention, no vegetation was present. After sixteen months, plots spread with material from local fens had greater cover of fen-characteristic plants (21–32%) than plots that were not spread with material (6–10%). Plots spread with fen material also contained more fen-characteristic plant species (10–15) than plots that were not spread (5–8). Patterns were similar six months after sowing (see original paper). 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. In May 2001, 54 plots (each 5 x 5 m) were established, in three equal blocks, on a historically mined bog. Surface vegetation and soil from moss- or grass-dominated fens was spread onto 36 plots (12 random plots/block) but not the other 18 plots (three plots/block). All plots had been prepared by rewetting, raking and fertilizing. In October 2001 and August 2002, cover of every plant species was estimated in ten 30 x 30 cm quadrats/plot.

16 

A replicated, randomized, paired, before-and-after study in 1995–2001 in a historically mined bog in Quebec, Canada (Chirino et al. 2006) reported that plots sown with Sphagnum-dominated vegetation fragments (and rewetted and mulched) developed Sphagnum cover. Before sowing, plots were bare peat. After four growing seasons, Sphagnum cover was 23–48%. Plots sown with vegetation dominated by rusty bog moss Sphagnum fuscum had significantly greater Sphagnum cover (48%) than plots sown with vegetation dominated by three other single species (red bog moss Sphagnum rubellum 34%; fine bog moss Sphagnum angustifolium: 30%; Magellan’s bog moss Sphagnum magellanicum: 23%). Overall, there was no significant difference in Sphagnum cover between plots sown with single species (23–48%) or mixed species (32–40%). Each spring between 1995 and 1998, forty-five 30 m2 plots were established (in five blocks of nine) on bare rewetted peat. Within each block, four random plots were sown with vegetation dominated by a single Sphagnum species and five were sown with vegetation containing a mixture of 2–4 species. All plots were then mulched with straw. Sphagnum cover was visually estimated each autumn, for four years after sowing.

17 

A replicated, randomized, paired, controlled, before-and-after study in 2004–2006 in a historically mined bog in Quebec, Canada (Graf & Rochefort 2008) found that plots sown with vegetation fragments developed greater plant species richness and Sphagnum moss cover than unsown plots, but similar total vegetation and herb cover. Before sowing, plots were bare peat. After two years, sown 30 m2 plots contained more plant species than unsown plots (24 vs 22) and had greater Sphagnum cover (13 vs 0%). There was no significant difference between sown and unsown plots for total vegetation cover (41 vs 36%), total herb cover (approximately 30%) or sedge Carex spp. cover (3 vs 2%). The study also found greater total vegetation, Sphagnum and sedge cover in plots receiving vegetation from moss-dominated fens than from grass-dominated fens (see original paper). 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. In May–August 2004, vegetation fragments from moss- or grass-dominated fens were spread onto 30 cleared and levelled 5 x 6 m plots. Ten similar plots received no donor material. Some sown and unsown plots were also fertilized and mulched with straw. In September 2006, cover of every plant species was estimated in 10–20 quadrats/plot.

18 

A replicated, controlled study in 2012–2014 in a historically mined bog in Estonia (Karofeld et al. 2016) found that plots sown with vegetation fragments developed greater cover of bryophytes and vascular plants than an unsown plot, and had plant communities more like the donor bog. After 1–2 years, sown plots had greater cover than an unsown plot of total bryophytes (52–65% vs 5%), Sphagnum mosses (50–54% vs 2%) and vascular plants (17–21% vs 12%). Sheathed cottongrass Eriophorum vaginatum and sedge Carex sp. were present in at least one sown plot (cover <1%), but not in the unsown plot. After two years, the overall plant community in sown plots was 40–67% similar to the donor bog, compared to 28–45% similarity between the unsown plot and donor bog. In spring 2012, three plots were sown with plant fragments (mostly Sphagnum mosses) from the surface of a nearby bog. One additional plot was not sown. All plots had been reprofiled (top 20 cm of peat pushed into ridges around the plot) and rewetted and were mulched with straw. In June and September 2013 and 2014, vegetation cover was estimated in ten 50 x 50 cm quadrats/plot.

Referenced papers

Please cite as:

Taylor N.G., Grillas P. & Sutherland W.J. (2018) Peatland Conservation: Global Evidence for the Effects of Interventions to Conserve Peatland Vegetation. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.