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Providing evidence to improve practice

Action: Excavate pools (without planting) Peatland Conservation

Key messages

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  • Two studies evaluated the effects of excavating pools (without planting) on peatland vegetation. Both studies were based on the same experimental set-up in bogs in Canada.
  • Plant community composition (1 study): One replicated, before-and-after, site comparison study in bogs in Canada reported that excavated pools were colonized by peatland vegetation over 4–6 years, but contained different plant communities to natural pools. In particular, cattail was more common in created pools.
  • Vegetation cover (1 study): 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.
  • Overall plant richness/diversity (1 study): 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.

Supporting evidence from individual studies

1 

A replicated, before-and-after, site comparison study in 1999–2003 in four bogs in eastern Canada (Mazerolle et al. 2006) found that created pools developed vegetation cover within four years, but reported that this remained lower than cover in and around natural pools. Initially, the created pools contained no vegetation. After four years, Sphagnum moss cover had increased to 9% (vs 80% in natural pools), herb cover had increased to 5% (natural: 10%) and shrub cover had increased to 5% (natural: 27%). Comparisons with natural pools were not tested for statistical significance. In 1999, four 6 x 8.5 m pools were created in one historically mined bog by excavating and rewetting (blocking drainage ditches and building embankments). No vegetation was introduced to these, although the surrounding site was sown with bog vegetation fragments. In 2003, vegetation cover was recorded in 36 quadrats/pool, each 30 x 30 cm, along six bank-to-bank transects. Vegetation cover of 70 natural pools, in unmined parts of nearby bogs, was recorded in 1999 and 2000. This study was based on the same experimental set-up as (2).

2 

A replicated, before-and-after, site comparison study in 1999–2005 in seven bogs in Quebec, Canada (Fontaine et al. 2007) reported that created pools developed a different plant community to natural pools, but with similar species richness. After six years, the overall composition of the plant community differed between created and natural pools (data reported as a turnover index and graphical analysis). In particular, cattail Typha latifolia was more frequent in created pools (occurring in 69% of quadrats) than natural pools (0% of quadrats). Sphagnum mosses, Eriophorum cottongrasses and Carex sedges were sometimes more abundant in restored pools and sometimes less abundant, depending on the species (see original paper). Created and natural pools both contained 24 plant species/0.5 m2. In 1999, four 6 x 12 m pools were created in a historically mined bog by excavating and rewetting (blocking drainage ditches and building embankments). In 2005, cover of every plant species was estimated in 0.5 m2 quadrats situated on pool margins: 12 quadrats around the created pools and 30 around pools in each of six natural, unmined bogs. This study was based on the same experimental set-up as (1).

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.