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What Works in Conservation 2020

 | 
William J. Sutherland
, 
Lynn V. Dicks
, 
Silviu O. Petrovan
, 
et al.

6. Peatland conservation

6.11 Habitat creation and restoration

Texte intégral

1 Remember, the effectiveness category for each intervention assumes that the aims of the intervention match your management goals. You should consider whether each intervention is necessary and appropriate in your focal peatland.

6.11.1 General habitat creation and restoration

Likely to be beneficial

Restore/create peatland vegetation (multiple interventions)

2Plant community composition: 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.

3Characteristic plants: One controlled study, in a fen in France, reported that restoration interventions increased cover of fen-characteristic plants.

4Moss cover: Five studies (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.

5Herb cover: Five studies (one replicated, paired, controlled, before-and-after) in peatlands in the Czech Republic, the UK, Estonia and Canada reported that restoration interventions increased cover of herbs, including cottongrasses Eriophorum spp. and other grass-like plants.

6Overall vegetation cover: Three studies (one replicated, controlled, before-and-after) in bogs in the UK and France reported that restoration interventions increased overall vegetation cover.

7Assessment: likely to be beneficial (effectiveness 75 %; certainty 60 %; harms 5 %). Based on evidence from: bogs (six studies); fens (one study); mixed or unspecified peatlands (two studies).

8https://www.conservationevidence.com/​actions/​1803

Restore/create peatland vegetation using the moss layer transfer technique

9Plant community composition: One replicated study in bogs in Canada reported that the majority of restored areas developed a community of bog-characteristic plant species within eleven years. One controlled, before-and-after study in a bog in Canada reported that a restored area (included in the previous study) developed a more peatland-characteristic plant community over time, and relative to an unrestored area.

10Vegetation cover: Two controlled studies in one bog in Canada reported that after 4–8 years, a restored area had greater cover than an unrestored area of mosses and bryophytes (including Sphagnum spp.) and herbs (including cottongrasses Eriophorum spp.), but less cover of shrubs. One of the studies reported that vegetation in the restored area became more similar to local natural bogs.

11Overall plant richness/diversity: One controlled, before-and-after study in a bog in Canada reported that after eight years, a restored area contained more plant species than an unrestored area.

12Assessment: likely to be beneficial (effectiveness 70 %; certainty 60 %; harms 1 %). Based on evidence from: bogs (four studies).

13https://www.conservationevidence.com/​actions/​1804

6.11.2 Modify physical habitat only

Likely to be beneficial

Fill/block ditches to create conditions suitable for peatland plants

14Vegetation cover: Two studies, in a bog in the UK and a fen in the USA, reported that blocked or filled ditches were colonized by peatland vegetation within 2–3 years. In the USA, vegetation cover was restored to natural, undisturbed levels. One replicated study in bogs in the UK reported that plants had not colonized blocked gullies after six months.

15Overall plant richness/diversity: One site comparison study in a fen in the USA found that after two years, a filled ditch contained more plant species than adjacent undisturbed fen.

16Assessment: likely to be beneficial (effectiveness 60 %; certainty 50 %; harms 0 %). Based on evidence from: bogs (two studies); fens (one study).

17https://www.conservationevidence.com/​actions/​1805

Remove upper layer of peat/soil

18Plant community composition: Five studies (one replicated, randomized, paired, controlled) in a peatland in the USA and fens or fen meadows in the Netherlands and Poland reported that plots stripped of topsoil developed different plant communities to unstripped peatlands. In one study, the effect of stripping was not separated from the effect of rewetting. Two studies in fen meadows in Germany and Poland reported that the depth of soil stripping affected plant community development.

19Characteristic plants: Four studies (one replicated, randomized, paired, controlled) in fen meadows in Germany and the Netherlands, and a peatland in the USA, reported that stripping soil increased cover of wetland- or peatland-characteristic plants after 4–13 years. In the Netherlands, the effect of stripping was not separated from the effect of rewetting. One replicated site comparison study in fens in Belgium and the Netherlands found that stripping soil increased fen-characteristic plant richness.

20Herb cover: Three studies (one replicated, paired, controlled) in fens or fen meadows in Germany, the UK and Poland found that stripping soil increased rush, reed or sedge cover after 2–6 years. One controlled study in a fen meadow in the Netherlands reported that stripping soil had no effect on cover of true sedges Carex spp. or velvety bentgrass Agrostis canina after five years. Two controlled studies, in fens or fen meadows in the Netherlands and the UK, found that stripping soil reduced cover of purple moor grass Molinia caerulea for 2–5 years.

21Vegetation structure: Two studies, in fens or fen meadows in the Netherlands and Belgium, found that stripping soil reduced vegetation biomass (total or herbs) for up to 18 years. One replicated, randomized, paired, controlled study in a peatland in the USA found that stripping soil did not affect vegetation biomass after four years.

22Overall plant richness/diversity: Three studies (one replicated, paired, controlled) in fens or fen meadows in the UK, Belgium and the Netherlands reported that stripping soil increased total plant species richness over 2–18 years. In one study, the effect of stripping was not separated from the effect of rewetting. One replicated, controlled study in a fen in Poland found that stripping soil had no effect on plant species richness after three years. One replicated, randomized, paired, controlled study in a peatland in the USA found that stripping soil increased plant species richness and diversity, after four years, in one field but decreased it in another. One replicated study in a fen meadow in Poland reported that plant species richness increased after soil was stripped.

23Assessment: likely to be beneficial (effectiveness 55 %; certainty 50 %; harms 10 %). Based on evidence from: fen meadows (six studies); fens (three studies); unspecified peatlands (one study).

24https://www.conservationevidence.com/​actions/​1809

Unknown effectiveness (limited evidence)

Excavate pools

25Plant community composition: One replicated, before-and-after, site comparison study in bogs in Canada reported that excavated pools were colonized by some peatland vegetation over 4–6 years, but contained different plant communities to natural pools. In particular, cattail Typha latifolia was more common in created pools.

26Vegetation cover: One replicated, before-and-after, site comparison study in bogs in Canada reported that after four years, created pools had less cover than natural pools of Sphagnum moss, herbs and shrubs.

27Overall plant richness/diversity: One replicated, before-and-after, site comparison study in bogs in Canada reported that after six years, created pools contained a similar number of plant species to natural pools.

28Assessment: unknown effectiveness – limited evidence (effectiveness 45 %; certainty 38 %; harms 5 %). Based on evidence from: bogs (two studies).

29https://www.conservationevidence.com/​actions/​1806

Reprofile/relandscape peatland

30Plant community composition: One site comparison study in Canada reported that after five years, reprofiled and rewetted bogs (being restored as fens) contained a different plant community to nearby natural fens.

31Vegetation cover: The same study reported that after five years, reprofiled and rewetted bogs (being restored as fens) had lower vegetation cover than nearby natural fens (specifically Sphagnum moss, other moss and vascular plants).

32Assessment: unknown effectiveness – limited evidence (effectiveness 40 %; certainty 20 %; harms 10 %). Based on evidence from: bogs (one study).

33https://www.conservationevidence.com/​actions/​1807

Disturb peatland surface to encourage growth of desirable plants

34Plant community composition: Two replicated, paired, controlled, before-and-after studies (one also randomized) in fens in Germany and Sweden reported that soil disturbance affected development of the plant community over 2–3 years. In Germany, disturbed plots developed greater cover of weedy species from the seed bank than undisturbed plots. In Sweden, the community in disturbed and undisturbed plots became less similar over time.

35Characteristic plants: The same two studies reported that wetland- or fen-characteristic plants colonized plots that had been disturbed (along with other interventions). The study in Germany noted that no peat-forming species colonized the fen.

36Assessment: unknown effectiveness – limited evidence (effectiveness 45 %; certainty 30 %; harms 20 %). Based on evidence from: fens (two studies).

37https://www.conservationevidence.com/​actions/​1811

Add inorganic fertilizer

38Vegetation cover: One replicated, randomized, paired, controlled, before-and-after study in a bog in New Zealand reported that fertilizing typically increased total vegetation cover.

39Vegetation structure: One replicated, paired, controlled study in a fen meadow in the Netherlands found that fertilizing with phosphorous typically increased total above-ground vegetation biomass, but other chemicals typically had no effect.

40Overall plant richness/diversity: One replicated, randomized, paired, controlled, before-and-after study in a bog in New Zealand reported that fertilizing typically increased plant species richness.

41Growth: One replicated, controlled, before-and-after study in a bog in Germany found that fertilizing with phosphorous typically increased herb and shrub growth rate, but other chemicals had no effect.

42Other: Three replicated, controlled studies in a fen meadow in Germany and bogs in Germany and New Zealand reported that effects of fertilizer on peatland vegetation were more common when phosphorous was added, than when nitrogen or potassium were added.

43Assessment: unknown effectiveness – limited evidence (effectiveness 50 %; certainty 30 %; harms 15 %). Based on evidence from: bogs (two studies); fen meadows (one study).

44https://www.conservationevidence.com/​actions/​1812

Cover peatland with organic mulch

45Vegetation cover: One replicated, randomized, paired, controlled, before-and-after study in a bog (being restored as a fen) in Canada found that mulching bare peat 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.

46Characteristic plants: One replicated, randomized, paired, controlled, before-and-after study in a bog (being restored as a fen) in Canada found that covering bare peat with straw mulch increased the number of fen characteristic plants, but not their overall cover.

47Assessment: unknown effectiveness – limited evidence (effectiveness 40 %; certainty 30 %; harms 5 %). Based on evidence from: bogs (two studies).

48https://www.conservationevidence.com/​actions/​1813

Cover peatland with something other than mulch

49Vegetation cover: One replicated, controlled, before-and-after study in a bog in Germany reported that covering bare peat with fleece or fibre mats did not affect the number of seedlings of five herb/shrub species. One replicated, controlled, before-and-after study in bogs in Australia reported that recently-burned plots shaded with plastic mesh developed greater cover of native plants, forbs and Sphagnum moss than unshaded plots.

50Assessment: unknown effectiveness – limited evidence (effectiveness 40 %; certainty 30 %; harms 5 %). Based on evidence from: bogs (two studies).

51https://www.conservationevidence.com/​actions/​1814

Stabilize peatland surface to help plants colonize

52Vegetation cover: One controlled, before-and-after study in a bog in the UK found that pegging coconut fibre rolls onto almost-bare peat did not affect the development of vegetation cover (total, mosses, shrubs or common cottongrass Eriophorum angustifolium).

53Assessment: unknown effectiveness – limited evidence (effectiveness 20 %; certainty 20 %; harms 5 %). Based on evidence from: bogs (one study).

54https://www.conservationevidence.com/​actions/​1815

Build artificial bird perches to encourage seed dispersal

55Vegetation cover: One replicated, paired, controlled study in a peat swamp forest in Indonesia found that artificial bird perches had no significant effect on tree seedling abundance.

56Assessment: unknown effectiveness – limited evidence (effectiveness 20 %; certainty 20 %; harms 1 %). Based on evidence from: tropical peat swamps (one study).

57https://www.conservationevidence.com/​actions/​1817

No evidence found (no assessment)

58We have captured no evidence for the following interventions:

  • Roughen peat surface to create microclimates
  • Bury upper layer of peat/soil
  • Introduce nurse plants.

6.11.3 Introduce peatland vegetation

Beneficial

Add mosses to peatland surface

59Sphagnum moss cover: Eleven studies in bogs in the UK, Canada, Finland and Germany and fens in 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 there was more Sphagnum in sown than unsown plots. One additional study in Canada found that adding Sphagnum to bog pools did not affect Sphagnum cover.

60Other moss cover: 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 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.

61Assessment: beneficial (effectiveness 78 %; certainty 70 %; harms 1 %). Based on evidence from: bogs (eleven studies); fens (two studies).

62https://www.conservationevidence.com/​actions/​1821

Add mixed vegetation to peatland surface

63Characteristic plants: One replicated, randomized, paired, controlled, before-and-after study in a degraded bog (being restored as a fen) in Canada found that adding fen vegetation increased the number and cover of fen-characteristic plant species.

64Sphagnum moss cover: 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.

65Other moss cover: 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 ranged from <1 to 65 %.

66Vascular plant cover: 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.

67Assessment: beneficial (effectiveness 78 %; certainty 68 %; harms 1 %). Based on evidence from: bogs (eighteen studies).

68https://www.conservationevidence.com/​actions/​1822

Likely to be beneficial

Directly plant peatland mosses

69Survival: One study in Lithuania reported that 47 of 50 Sphagnum-dominated sods planted into a rewetted bog survived for one year.

70Growth: Two before-and-after studies, in a fen in the Netherlands and bog pools in the UK, reported that mosses grew after planting.

71Moss cover: Five before-and-after studies in a fen in the Netherlands and bogs in Germany, Ireland, Estonia and Australia reported that after planting mosses, the area covered by moss increased in at least some cases. The study in the Netherlands reported spread of planted moss beyond the introduction site. The study in Australia was controlled and reported that planted plots developed greater Sphagnum moss cover than unplanted plots.

72Assessment: likely to be beneficial (effectiveness 75 %; certainty 60 %; harms 0 %). Based on evidence from: bogs (six studies); fens (one study).

73https://www.conservationevidence.com/​actions/​1818

Directly plant peatland herbs

74Survival: Three replicated studies, in a fen meadow in the Netherlands and fens in the USA, reported that planted herbs survived over 2–3 years. However, for six of nine species only a minority of individuals survived.

75Growth: Two replicated before-and-after studies, in a bog in Germany and fens in the USA, reported that planted herbs grew.

76Vegetation cover: One replicated, controlled, before-and-after study in Canada found that planting herbs had no effect on moss, herb or shrub cover in created bog pools relative to natural colonization.

77Assessment: likely to be beneficial (effectiveness 50 %; certainty 40 %; harms 0 %). Based on evidence from: bogs (two studies); fens (two studies); fen meadows (one study).

78https://www.conservationevidence.com/​actions/​1819

Directly plant peatland trees/shrubs

79Survival: Eight studies (seven replicated) in peat swamp forests in Thailand, Malaysia and Indonesia and bogs in Canada reported that the majority of planted trees/shrubs survived over periods between 10 weeks and 13 years. One study in a peat swamp forest in Indonesia reported <5 % survival of planted trees after five months, following unusually deep flooding. One replicated study in a fen in the USA reported that most planted willow Salix spp. cuttings died within two years.

80Growth: Four studies (including two replicated, before-and-after) in peat swamp forests in Thailand, Indonesia and Malaysia reported that planted trees grew. One replicated before-and-after study in bogs in Canada reported that planted shrubs grew.

81Assessment: likely to be beneficial (effectiveness 70 %; certainty 50 %; harms 0 %). Based on evidence from: tropical peat swamps (seven studies); bogs (three studies); fens (one study).

82https://www.conservationevidence.com/​actions/​1820

Introduce seeds of peatland herbs

83Germination: Two replicated studies (one also controlled, before-and-after) reported that some planted herb seeds germinated. In a bog in Germany three of four species germinated, but in a fen in the USA only one of seven species germinated.

84Characteristic plants: Three studies (two controlled) in fen meadows in Germany and a peatland in China reported that wetland-characteristic or peatland-characteristic plants colonized plots where herb seeds were sown (sometimes along with other interventions).

85Herb cover: Three before-and-after studies (one also replicated, randomized, paired, controlled) in a bog in New Zealand, fen meadows in Switzerland and a peatland in China reported that plots sown with herb seeds developed cover of the sown herbs (and, in New Zealand, greater cover than unsown plots). In China, the effect of sowing was not separated from the effects of other interventions. One replicated, randomized, paired, controlled study in a fen in the USA found that plots sown with herb (and shrub) seeds developed similar herb cover to plots that were not sown.

86Overall vegetation cover: Of three replicated, controlled studies, one in a fen in the USA found that sowing herb (and shrub) seeds increased total vegetation cover. One study in a bog in New Zealand found that sowing herb seeds had no effect on total vegetation cover. One study in a fen meadow in Poland found that the effect of adding seed-rich hay depended on other treatments applied to plots.

87Overall plant richness/diversity: Two replicated, controlled studies in fens in the USA and Poland found that sowing herb seeds had no effect on plant species richness (total or vascular). Two replicated, controlled, before-and-after studies in a bog in New Zealand and a fen meadow in Poland each reported inconsistent effects of herb sowing on total plant species richness.

88Assessment: likely to be beneficial (effectiveness 50 %; certainty 50 %; harms 0 %). Based on evidence from: fen meadows (four studies); fens (three studies); bogs (two studies); unspecified peatlands (one study).

89https://www.conservationevidence.com/​actions/​1823

Introduce seeds of peatland trees/shrubs

90Germination: Two replicated studies in a bog in Germany and a fen in the USA reported germination of heather Calluna vulgaris and hoary willow Salix candida seeds, respectively, in at least some sown plots.

91Survival: The study in the bog Germany reported survival of some heather seedlings over two years. The study in the fen in the USA reported that all germinated willow seedlings died within one month.

92Shrub cover: Two studies (one replicated, randomized, paired, controlled) in bogs in New Zealand and Estonia reported that plots sown with shrub seeds, sometimes along with other interventions, developed greater cover of some shrubs than plots that were not sown: sown manuka Leptospermum scoparium or naturally colonizing heather Calluna vulgaris (but not sown cranberry Oxycoccus palustris). One replicated, randomized, paired, controlled study in a fen in the USA found that plots sown with shrub (and herb) seeds developed similar overall shrub cover to unsown plots within two years.

93Overall vegetation cover: Two replicated, randomized, paired, controlled studies in a bog in New Zealand and a fen in the USA reported that plots sown with shrub (and herb) seeds developed greater total vegetation cover than unsown plots after two years. One site comparison study in bogs in Estonia reported that sowing shrub seeds, along with fertilization, had no effect on total vegetation cover after 25 years.

94Overall plant richness/diversity: One site comparison study in bogs in Estonia reported that sowing shrub seeds, along with fertilization, increased plant species richness. However, one replicated, randomized, paired, controlled study in a bog in New Zealand reported that plots sown with shrub seeds typically contained fewer plant species than plots that were not sown. One replicated, randomized, paired, controlled study in a fen in the USA found that sowing shrub (and herb) seeds had no effect on plant species richness.

95Assessment: likely to be beneficial (effectiveness 45 %; certainty 40 %; harms 5 %). Based on evidence from: bogs (three studies); fens (two studies).

96https://www.conservationevidence.com/​actions/​1824

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