Post on 23-Sep-2020
transcript
Richard Archer Thursday 1 December 2016
Locking up carbon in the Somerset Levels
• 2nd largest area lowland organic soil in UK
• 2,500 ha moss peat, 12,500 ha sedge peat
• Total c. 10.9 M tonnes?
SL&M C store
• Peat wastage 4-8 mm pa? (>12 mm pa?) 6 mm = 20,000 t C pa
• Peat extraction - 1,400 t peat extraction + Baltic peat
• C sequestration – zero?
• Net loss 0.2% pa
SL&M C peat balance sheet
LIDAR – GLK & WSR
4-6 cm difference between SSSI pasture and former arable
Traditional floodplain pasture & hay meadow: 6,000 ha – largest remaining area in UK
• Summer pen: 1 Apr water at field level
• MG8 – water table down to 20 cm
• Snipe/curlew like MG8 hay meadow
• Lapwing/redshank splash
• Aug onwards – maintenance
• Winter pen: mid Dec mean field levels
• No DWR on MG8 wader fields
• No dry ditches
RWLA water management 1
RWLA management favourable for peat soils:
1. Minimise variation in soil moisture content to minimise peat degradation
2. Key factor: don’t allow summer water table to fall below 50 cm.
3. Spring & summer – water table max 30 cm below mean field level
4. High ditch levels don’t guarantee high field groundwater levels
5. Ditch / foot drain / gutter spacing critical – 20 m?
6. Big hydro blocks to minimise mgt & costs
7. Also protects buried archaeology
RWLA water management 2
• RWLAs c.2,000 ha
• SSSIs c.6,000 ha - CO’s adequate?
• 7,500 ha poor peat mgt?
Scale of peat wastage
• Declining output• 1,400 t C per annum. Much smaller than agriculture• Not destroying good habitat• Milled with Baltic peat• Last big new permission Cradlebridge• NPPF – no extensions, except where clear
environmental gain• Habs Regs Review
Peat extraction
1. Short-term – protect what we have:• SPA/Ramsar/RWLAs• Improve SSSI mgt• Create new lowland mire?
2. Medium-term:• C offset market, alternative LWG revenues e.g. biomass• Non-peat alternatives
3. Long-term – climate-proof:• Drought – upper catchment storage?• Bigger hydro units• ?
The Future – a few thoughts
Thank you
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