Peatland Rewetting in the South West


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First of three presentations at the Agricultural Law Association meeting on 26 February 2013, presented by Dr David Smith of South West Water

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  • 1. Gas fluxes are measured from the surface of the peatlands using closed chambers. 2. Each site is fitted with permanent ground collars onto which the chamber is placed during gas collection. 3. The chamber is sealed with a gas-tight lid. 4. Gas samples are collected over a 15-min period every 5 minutes and the change of concentration with time of the gas species is used to determine their flux rate (taking into account chamber volume, internal temperature and the foot print of the chamber). 5. A balloon on the inside on the chamber is connected to the external air. It helps dampen any sudden pressure changes that might trigger ebullition events (i.e., sporadic bubble release from the soil). 6. The vent tube allows outside air to enter the chamber at the same rate that it is being withdrawn during sample collection. The total volume of each sample is ~60 ml (1 x 20 ml sample + duplicate flushing). The amount of ‘fresh’ air entering the chamber is taking into account in the flux data processing (i.e., as a dilution). The vent tube prevent negative pressure from forming in the chamber which could trigger or enhance the rate of gas release from soil.
  • Peatland Rewetting in the South West

    1. 1. Peatland Restoration in South West England ALA South West Regional Meeting 26th February 2013Dr. David Smith – South West Water and Exmoor Mires Project Manager
    2. 2. Distribution of upland peatlands in the South West of England
    3. 3. The mires on ExmoorDrainage for agricultural improvement
    4. 4. Domestic and commercial peat cutting for fuel Cutting carried on until the end of the c20th
    5. 5. Exmoor peatlands have become largely dry and dominated byMolinia (sedge grass) as a result
    6. 6. Exmoor Mires Project• Initiated in 1998 by ENPA, EA and NE. First restoration work at Exe-head in 2001-4 aimed to benefit the River Exe.• New Partnership for 2006-9 project included SWW and Wildlife restoration was the main funding aim.• 2010-15 SWW customers funded project for water supply, quality and wildlife.
    7. 7. What has the project achieved?• The blocking of 50km of ditch and the re- wetting of 400ha of mire at 20 locations
    8. 8. Where?- the pink bits
    9. 9. How is restoration done?• Peat blocks, wooden blocks and bales
    10. 10. What equipment is used?• Tracked or low impact machinery
    11. 11. What is the end result• Most sites get a bit wetter and a some have got a lot wetter in places
    12. 12. Ditch blocks on a typical site with lots of small ditches
    13. 13. Ditch blocks on big ditches = Pools
    14. 14. Current Exmoor Project 2010- 15• £2m budget for Exmoor• 2000ha target restoration area• 2800ha of peatland has been surveyed, the ditches/peat-cuttings measured and GPS mapped and the restoration potential assessed.• Restoration has been identified as possible on 2000ha.• Restoration carried out on over 100ha so far
    15. 15. 2012 restoration areas
    16. 16. Before Gully following restorationBlocking in progress
    17. 17. Eroded area immediately after restoration
    18. 18. Proof of Concept monitoring Plant monitoring has found anincrease in Sphagnum species and less Molinia
    19. 19. Other Wildlife monitoring (Birds, dragonflies, amphibians, reptiles, etc)Dragonflies example is typical of increases; Black Darter- (rare on Exmoor as it needs bog pools) Blackpitts now has possibly the largest population in Somerset (100’s seen in 2011) Common Hawker-(rare in southern England) x10 seen at Blackpitts and x2 at Squallacombe in 2012
    20. 20. Agricultural Impact of Mire restoration monitoring• base line survey started this year by WRT,• post-restoration surveys in subsequent years.
    21. 21. Hydrological Monitoring: Water storage and quality changes•Monitoring Equipment per site:54 dipwells, 18 temperature loggers, 60capacitance probes, 30 mini conductivityloggers, 3 seepage meters.
    22. 22. Monitoring GHG flux and storage Internal balloon (to dampen pressure changes)Vent Tube Lid & chamber Fan to mix chamber air Sample Chamber, Outlet lid and Temperature and collar are relative humidity sealed logger using a Ground Collars water-filled groove
    23. 23. Why Monitor?• Need to prove to the Water Regulator that peatland restoration achieves its aims of improving water supply and quality.• The outcome information is also needed for the set-up of a revenue payment for Mire restoration.