Maintain/restore water flow across service corridors

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

60%
Certainty

20%
Harms

1%

Calculating overall effectiveness category

Background information and definitions

Peatlands may depend upon natural inflows or outflows of water, both above and below the surface, to maintain appropriate moisture and chemical conditions. Transportation or service corridors can block these water flows. This impact can be avoided by careful design e.g. building using permeable materials, or building raised service corridors (but note that floating roads built without digging into peat still block surface flow, and often sink over time so will block subsurface flow). Alternatively, water flows can be restored by building culverts, pipes or water diversions.

Key peatland types where this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.

Related actions: rewetting more generally; restoring water level fluctuations.

Study locations

Key messages

One study evaluated the effects on peatland vegetation of restoring water flow across service corridors. The study was in a fen.
Characteristic plants (1 study): One before-and-after study in a fen in the USA found that following restoration of water inflow across a road (along with general rewetting), cover of wet peatland sedges increased whilst cover of grasses preferring drier conditions decreased.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A before-and-after study in 2002–2004 in a degraded fen in California, USA (Patterson & Cooper 2007) found that after water flow was restored across a road (along with general rewetting), cover of peatland-characteristic sedges increased whilst cover of grass species preferring drier conditions typically decreased. Cover of three sedge species characteristic of wet peatlands increased (two significantly or marginally so), from 12–15% before rewetting to 13–20% one year after. Cover of three grass species that prefer drier conditions decreased (two significantly), from 2–6% before rewetting to 1–5% one year after. In July 2003, 21 channels were created across a road that blocked surface water flow into the fen. At the same time, the main drainage ditch of the fen was dammed. The study does not distinguish between the effects of these interventions. Vegetation cover was estimated in July before (2002) and after (2004) intervention, in fifty-nine 10 m²plots.
Study and other actions tested
Referenced paper
Patterson L. & Cooper D.J. (2007) The use of hydrologic and ecological indicators for the restoration of drainage ditches and water diversions in a mountain fen, Cascade Range, California. Wetlands, 27, 290-304.

Please cite as:

Taylor, N.G., Grillas, P. & Sutherland, W.J. (2020) Peatland Conservation. Pages 367-430 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Peatland Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Maintain/restore water flow across service corridors Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Backfill trenches dug for pipelines Action Link	No evidence found (no assessment)	0	Synopsis Link
Retain/create habitat corridors across service corridors Action Link	No evidence found (no assessment)	0	Synopsis Link