Action: Maintain/restore water flow across service corridors
Key messagesRead our guidance on Key messages before continuing
- 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.
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.
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 m2 plots.