Leaky peat: a collaborative approach at Dalmellington Moss


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CEI project manager, Daisy, and Scottish Wildlife Trust (SWT) reserves manager, Gill Smart, led stakeholders on a visit to Dalmellington Moss SSSI to discuss the past and future management of the site. The attendees were Scottish Natural Heritage (SNH) Peatland Action Manager and wetland specialist, Andrew McBride, Galloway and Southern Ayrshire Biosphere Natural Heritage Officer, Emily Taylor, and Openspace (Cumbria) Ltd Director, Jonathon Rook.

The objective was to inspect a dam put in place in 2015 that has subsequently found to be leaking, and to collaborate on ideas to solve the problem. This approach was taken by the CEI as a way of bringing together site manager, contractor and wetland ecologists to share knowledge and come up with the most pragmatic solution to re-wet the bog.

 

Management of the site

Dalmellington Moss is a 28 hectare raised bog that has formed in the floodplain of the river Doon and is part of a wider network of wetland habitats, including birch and willow carr and mesotrophic fen. It began its slow formation many thousands of years ago and has accumulated 5 metres of peat in some areas.

Despite historical efforts to drain the bog, Dalmellington Moss is one of East Ayrshire’s best raised bogs and the majority of the site is in good condition thanks to appropriate management by owners SWT. There have been several phases of habitat enhancement since the 1990’s, including installation of tin dams and plastic piling by SWT and in 2015, the CEI installed peat dams and a deep trench bund as part of the Nature Network project.

The SWT and CEI work together to monitor the habitat condition and wildlife species at Dalmellington Moss, with the help of a great team of volunteers. Recent analysis of the hydrological monitoring data by Pendleton Hydro Ltd has shown that the water table is high and stabilising across the bog, particularly behind the new trench bunds. However, the newly installed peat dams in a large ditch are not working as intended. In particular, one of the four peat dams was found to retain water for less time that the other dams following a period of rainfall. Without addressing this problem, it is likely that the areas close to the ditch will continue to be effected by water loss and result in further drying of the peat.

 

Results of visit

The group met at Dalmellington Moss on the 9th September. Daisy led the group across the northern boundary of the bog to look at development of the deep trench bund 18 months after installation. The bund was created using in-situ wet peat dug to 1.5 metres, which created a sub-surface barrier that slows water loss that was previously draining into the northern boundary ditch. This ditch was not dammed because it runs along the A713 road and ditch-blocking would have posed a flooding risk.

The bund remains intact along its entire length (1.2km) and there are shallow areas of standing water which have started to colonise with cottongrass and sphagna and there are numerous dragonflies and beetles to be seen. Over time, these pools will fill with vegetation. The group commented that the bund appears to be well constructed and is holding back water which can be seen metres away from the bund.

The large ditch was inspected along its length. There are four large peat dams (installed in 2015) that have been constructed on top of plastic piling dams (installed in 2005). The group took several peat cores near to the leaky dam and commented that the peat was of good quality, with some signs of oxidisation in the top 10cm approx. Several metres away from the dam, it was possible to probe into an area of disturbed peat with ease, indicating a sub-surface crack. The group agreed that water could be bypassing the dam and ending up back in the ditch downstream.

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Peatland specialist, Emily Taylor, inspects a crack in the peat

The general agreement was that further measures should be implemented to prevent ongoing water loss surrounding the ditch. Suggestions came forward to install short peat bunds keying in with the existing dams and extending up the marginal slope of the ditch, and that this could help push water up the slope and re-wet the degraded margins, eventually reducing the purple moor-grass which dominates here. It was also suggested that there were too few dams in the ditch (for its size) and to install several more.

The CEI have funding to carry out further work this winter as part of the EcoCo LIFE project, and will continue to monitor the hydrological changes at Dalmellington Moss SSSI for the duration of the project.