Action: Restore/create peatland vegetation (multiple interventions)
- Nine studies evaluated the effects of multiple restoration interventions (other than the moss layer transfer technique) on peatland vegetation. Six studies were in bogs (one being restored as a fen). One study was in a fen. Two studies were in unspecified or mixed peatlands.
- Plant community composition (3 studies): One replicated, controlled, before-and-after study in the UK reported that the overall plant community composition differed between restored and unrestored bogs. One replicated, controlled, site comparison study in Estonia found that restored and natural bogs contained more similar plant communities than unrestored and natural bogs. However, one site comparison study in Canada reported that after five years, bogs being restored as fens contained a different plant community to natural fens.
- Characteristic plants (1 study): One controlled study in a fen in France reported that restoration interventions increased cover of fen-characteristic plants.
- Moss cover (7 studies): Five studies (including one replicated, paired, controlled, before-and-after) in bogs or other peatlands in the UK, Estonia and Canada found that restoration interventions increased total moss (or bryophyte) cover. Two studies (one replicated and controlled) in bogs in the Czech Republic and Estonia reported that restoration interventions increased Sphagnum moss cover, but one replicated before-and-after study in bogs in the UK reported no change in Sphagnum cover following intervention. Two site comparison studies in Canada reported that after 1–15 years, restored areas had lower moss cover than natural fens.
- Herb cover (5 studies): Five studies (one replicated, paired, controlled, before-and-after) in bogs or other peatlands in the Czech Republic, the UK, Estonia and Canada reported that restoration interventions increased cover of herbaceous plants, including cottongrass and other grass-like plants.
- Overall vegetation cover (3 studies): Three studies (one replicated, controlled, before-and-after) in bogs in the UK and France reported that restoration interventions increased overall vegetation cover.
Peatland creation and restoration schemes can involve many different specific interventions. This section considers peatland creation and restoration using more than three separate interventions at once, such that it is difficult to attribute outcomes to any single intervention. Where three or fewer interventions have been used together in a study, results are reported elsewhere on the website: under each intervention (but noting the influence of the others, where appropriate) or sometimes as a combined intervention (e.g. tree removal and rewetting).
Tree-colonized describes peatlands that would not naturally contain trees. Forested or swamps are used to describe peatlands with natural tree cover. Restored refers to areas where restoration interventions have been applied (i.e. undergoing the process of restoration) rather than the state of those areas (i.e. whether they have been successfully restored).
Key peatland types where this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.
Related action: restoration using the moss layer transfer technique, a specific combination of multiple interventions.
Supporting evidence from individual studies
A replicated, controlled, before-and-after study in 2007–2010 in a degraded blanket bog in England, UK (Anderson et al. 2011) reported that areas restored using multiple interventions developed a different plant community to unrestored areas, and found that they had greater vegetation cover. All areas were initially bare peat. Three years after intervention, the overall plant community composition differed between restored and unrestored areas (data reported as a graphical analysis; difference not tested for statistical significance). Restored areas had developed greater cover than an unrestored area of total vegetation (60–88% vs 15%), mosses (13–25% vs 1%) and heather Calluna vulgaris (2–25% vs 1%). Heather cover was particularly high in plots covered with heather brash. Note that most of the vegetation cover in restored areas was the nurse grass (33–47% cover). In winter 2007/2008, four areas (bare gully sides) were restored by sowing grass seed as a nurse crop (41 kg/ha, mix of six species), fertilization (nitrogen-phosphorous-potassium, 250 kg/ha), liming (1 t/ha) and gully blocking (with stone or heather bales). Two areas were also covered with heather brash (including heather seeds) and one covered in geojute matting. One additional area was not restored (received no intervention). Before monitoring began, sheep were excluded from the entire bog. Vegetation cover was estimated before (summer 2007) and after (summer 2010) restoration, in thirty 2 x 2 m quadrats/area.
A study in 1999–2007 in a historically mined bog in the Czech Republic (Horn 2012) reported that following multiple restoration interventions, bare peat was coloinized by vegetation including Sphagnum moss, cottongrasses Eriophorum spp. and beaked sedge Carex rostrata. These results were not tested for statistical significance. Of the bare peat present one year after restoration began, 30% was covered by vegetation seven years later. Over this time, Sphagnum cover increased from <2% to 8%. Cover also increased of common cottongrass Eriophorum angustifolium, sheathed cottongrass Eriophorum vaginatum and beaked sedge (data reported as maps). Between 1999 and 2004, a historically mined bog (with some remnant vegetation in drainage ditches) was subjected to multiple restoration interventions: rewetting by blocking drainage ditches, excavating shallow 10 x 10 m basins, planting cottongrasses and beaked sedge, sowing Sphagnum moss, mulching (both sown and unsown areas) with sedge cuttings, removing trees and stabilizing the peat surface with tree trunks. In 2000 and 2007, maps were made of where each plant species was dominant (or co-dominant).
A study in 2003–2008 in a historically mined raised bog in France (Pôle-Relais Tourbières 2013) reported that following restoration by multiple interventions, vegetation cover increased. No statistical tests were carried out. When intervention began, total vegetation cover was 14%. Five years later, it had increased to 51%. Restoration of 0.2 ha of drained, nutrient-enriched bog began in 2003. The top 20 cm of peat were removed, leaving an uneven surface. The stripped peat was used to build embankments and block a drainage ditch, rewetting the area. It was then planted (with sheathed cottongrass Eriophorum vaginatum, common cottongrass Eriophorum angustifolium and Sphagnum mosses) and mulched with straw. Annually between 2003 and 2008, vegetation cover was estimated in six 1 m2 quadrats across the restored area.
A replicated before-and-after study in 2002–2010 in five degraded blanket bogs in England, UK (Proctor et al. 2013) reported that following multiple restoration interventions, vegetation cover increased. These results are not based on tests of statistical significance. There were increases in total vegetation cover (before intervention: 2–14%; after eight years: 162–200%), cover of cottongrass Eriophorum spp. (before: 0%; after: 21–49%), cover of planted shrubs (before: 0%; after: 1–24%) and cover of mosses other than Sphagnum (before: 0%; after: 20–50%). The increase in Sphagnum moss cover was much smaller (before: 0%; after: <1%). Note that cover of nurse grasses, after eight years, was 27–50%. Between 2002 and 2008, five areas of bare peat were treated with multiple restoration interventions: building fences to exclude livestock, ditch blocking to raise the water table, liming, fertilization, adding brash (heather Calluna vulgaris) or a fibre mesh, sowing grass seeds, planting grass and shrub plants and spreading Sphagnum fragments. Vegetation cover was estimated before restoration began (2002), then annually between 2003 and 2010, in 4–44 variously sized quadrats/bog.
A replicated before-and-after study in 2008–2011 in a tree-colonized peatland in Scotland, UK (Kirkland 2014) reported that plots restored using multiple interventions developed herb and bryophyte cover. After 2–3 years, restored plots had 42% cover of rush Juncus spp., 21% cover of bryophytes, 10% cover of devil’s bit scabious Succisa pratensis and 20% cover of other vegetation (including heather Calluna vulgaris, grasses, sedges and other herbs). Cover of devil’s bit scabious did not significantly differ between grazed and ungrazed plots (data not reported). In October 2008, eight 16 m2 plots were restored by cutting and removing all conifer trees and sowing seeds of devil’s bit scabious. In four plots, conifer brash was burned after tree removal. Four plots were fenced to exclude deer. In August 2011, vegetation cover was visually estimated in five random 2 x 2 m quadrats/plot.
A replicated, controlled, site comparison study in 2012–2014 in a historically mined bog in Estonia (Karofeld et al. 2016) found that restoration by multiple interventions increased cover of bryophytes and vascular plants, and created a plant community more like the natural donor bog. After 1–2 years, restored plots had greater cover than an unrestored plot of all bryophytes combined (52–65% vs <1%), Sphagnum mosses (50–54% vs <1%) and vascular plants (17–23% vs 11%). Sheathed cottongrass Eriophorum vaginatum and sedge Carex sp. were present in at least one restored plot (cover <1%), but not in the unrestored plot. After two years, the overall plant community in restored plots was 40–67% similar to the unmined donor bog, compared to 21–29% similarity between the unrestored plot and donor bog. In spring 2012, three plots of almost-bare peat were restored by reprofiling (top 20 cm of peat pushed into ridges around the plot), rewetting (blocking a drainage ditch), adding plant fragments (mostly Sphagnum mosses) from the surface of a nearby bog and mulching with straw. One adjacent plot received no intervention. In June and September 2013 and 2014, vegetation cover was estimated in ten 50 x 50 cm quadrats in each plot and the donor bog.
A controlled study in 1997–2014 in a degraded fen in France (Pôle-Relais Tourbières 2016) reported that following restoration by multiple interventions, plant species richness and cover of fen-characteristic plants increased. No statistical tests were carried out. Fifteen years after intervention, there were 20 plant species in the fen (vs 12 when intervention began). Cover of fen-characteristic plants, including sedges Carex spp., was 50% (vs 2% when intervention began and vs 12% in an unrestored area of the fen). Restoration of a drained, abandoned, overgrown fen began in 1997–1999. The fen was rewetted by remeandering an adjacent river. Willow shrubs were cut and removed. Existing herbaceous vegetation and surface peat were shredded. Each summer between 1999 and 2004, the fen was grazed by horses. From 2004, a four year cycle of grazing-rest-mowing-rest was implemented in a mosaic across the fen. Between 1999 and 2014, cover of plant community types was estimated in the managed area (in four quadrats along a transect) and adjacent unmanaged fen (details not reported).
A site comparison study in 2008–2014 in a historically mined bog in Quebec, Canada (Rochefort et al. 2016) reported that an area restored using multiple interventions developed a different plant community to, with less vegetation cover than, nearby natural fens. These results were not tested for statistical significance. 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. Five years after intervention, the overall plant community composition of the restored area was different from three nearby natural fens (data reported as a graphical analysis). In the restored area, Sphagnum moss cover was only 3% (vs 15–25% in natural fens) and other moss cover only 3% (vs 12–55%). Vascular plant cover was only 26% (vs 59–86%), although the dominant species were similar in the restored fen and its donor fen. In winter 2009/2010, part of a historically mined bog (abandoned for nine years) was restored by rewetting (blocking drainage ditches with peat), excavating peat basins (removing surface peat and building embankments), sowing vegetation fragments from a moss-dominated donor fen, and mulching with straw. Vegetation cover was estimated in 2008 (donor fen; in 16 quadrats along a transect) or 2014 (restored area: in five 25 m2 plots).
A replicated, paired, controlled, before-and-after, site comparison study in five historically mined peatlands in Canada (Strack et al. 2016) found that restoration by multiple interventions increased cover of mosses, grass-like plants and vascular plants, but not shrubs. Restored and unrestored plots were initially bare peat. After 1–15 years, restored sites had significantly greater cover than unrestored sites of mosses (38 vs 3%), grass-like plants (22 vs 5%) and total vascular plants (33 vs 11%), but there was no significant difference in shrub cover (9 vs 3%). Relative to natural, undisturbed sites, restored sites had lower cover of mosses (38 vs 77%), shrubs (9 vs 27%) and total vascular plants (33 vs 44%), but higher cover of grass-like plants (22 vs 3%). Five degraded peatlands were restored (dates unclear) using a mixture of techniques. All received fresh vegetation fragments from the surface of natural peatlands and were mulched with straw. Some sites were levelled, rewetted and/or fertilized. Summer vegetation cover was estimated in restored sites after 1–15 years. For each restored site, vegetation cover of a natural peatland was estimated either before restoration or in separate untreated areas after restoration.
- Anderson P., Worrall P., Ross S., Hammond G. & Keen A. (2011) United Utilities Sustainable Catchment Management Programme Volume 3: The Restoration of Highly Degraded Blanket Bog. Penny Anderson Associates report. Penny Anderson Associates Report.
- Horn P. (2012) Ekologie rašelinišť na Šumavě. PhD Thesis. University of South Bohemia.
- Pôle-Relais Tourbières 0 (2013) Restoration of peatlands: trials of techniques for the restoration of the bogs on the Seignes in Frambouhans. French Peatland Coordination Centre
- Kirkland P. (2014) Experimental Marsh Fritillary Habitat Restoration Project Avongovie, Islay. Scottish Natural Heritage report.
- Karofeld E., Müür M. & Vellak K. (2016) Factors affecting re-vegetation dynamics of experimentally restored extracted peatland in Estonia. Environmental Science and Pollution Research, 23, 13706-13717
- Pôle-Relais Tourbières 0 (2016) La gestion par fauche des milieux humides de la Réser ve naturelle nationale du lac de Remoray. French Peatland Coordination Centre report. French Peatland Coordination Centre.
- Rochefort L., LeBlanc M.-C., Bérubé V., Hugron S., Boudreau S. & Pouliot R. (2016) Reintroduction of fen plant communities on a degraded minerotrophic peatland. Canadian Journal of Botany, 94, 1041-1051
- Strack M., Cagampan J., Hassanpour Fard G., Keith A.M., Nugent K., Rankin T., Robinson C. & Strachan I.B. (2016) Controls on plot-scale growing season CO2 and CH4 fluxes in restored peatlands: do they differ from unrestored and natural sites? Mires and Peat, 17, Article-5