Action: Slow down input water to allow more time for pollutants to be removed
Key messagesRead our guidance on Key messages before continuing
- One study evaluated the effects, on peatland vegetation, of slowing down input water to allow more time for pollutants to be removed. The study was in a fen.
- Characteristic plants (1 study): One before-and-after study in a floating fen in the Netherlands found that after input water was rerouted on a longer path (along with other interventions to reduce pollution), cover of mosses characteristic of low nutrient levels increased.
- Vegetation structure (1 study): The same study found that after input water was rerouted on a longer path (along with other interventions to reduce pollution), vascular plant biomass decreased.
Polluted water entering a peatland could be slowed down, allowing more time for natural breakdown or removal of pollutants before the water reaches the peatland. This could be facilitated by making input channels longer (e.g. Kooijman et al. 2016) or building a dam in the input channels (e.g. Bootsma et al. 2002). This intervention is mainly relevant to fens and fen meadows, which are fed by inputs of ground water. Bogs and tropical peat swamps are mainly fed by inputs of rainfall.
Key peatland types for which this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.
Bootsma M.C., van den Broek T., Barendregt A. & Beltman B. (2002) Rehabilitation of acidified floating fens by addition of buffered surface water. Restoration Ecology, 10, 112–121.
Kooijman A.M., Cusell C., Mettrop I.S. & Lamers L.P.M. (2016) Recovery of target bryophytes in floating rich fens after 25 yr of inundation by base-rich surface water with lower nutrient contents. Applied Vegetation Science, 19, 53–65.
Supporting evidence from individual studies
A before-and-after study in 1984–2013 in a floating rich fen in the Netherlands (Kooijman et al. 2016) found that after rerouting input water on a longer path (along with other interventions to reduce pollution), moss cover changed to species characteristic of lower nutrient levels, whilst vascular plant biomass decreased. Four of seven moss species characteristic of low nutrient levels increased in cover (from 1–62% four years before ditch extension to 11–83% eleven years after). Meanwhile, six of seven moss species characteristic of high nutrient levels decreased in cover (from 7–78% to 1–32%). Vascular plant biomass decreased from 1,123 g/m2 eight years before ditch extension to 287 g/m2 ten years after. In 1992, water entering the fen was rerouted on a longer path to allow more time for nutrient removal. The study does not distinguish between the effects of this intervention and the long term effects of two other interventions carried out since the 1970s: use of water purification facilities and switching the water source from a nutrient-rich river to a nutrient-poor lake. In 1988 and 2013, cover of every moss species was recorded in a 25 x 200 m area. In 1984 and 2012, above-ground vascular plant biomass was collected, dried and weighed.