Impact
Severe impact on ecology of some headwaters, reduced water storage in headwaters (and major emitter of carbon).
Quantum
62km of Upper Wye, Tarennig, Bidno and Irfon at risk of acid water flushes. Acid grassland streams are recovering steadily but those draining afforested deep peat over 350m ASL remain acidified. Increase in high water discharge (TBD) and reduction in low flows (17%).
Evidence
- United Kingdom Acid Waters Monitoring Network
- WUF spring acid waters survey
- North Devon Mires project
Cause
Elevated H+ deposition in 60’s 70’s and 80’s stripped metal ions from peat. Peat prevents their renewal. Acid substances are scrubbed by conifer leaves and wash off in acid flushes
Solutions
- Remove plantation forestry from deep peat soils over 350m by treating peat as a geomorphological unit and apply peat restoration tool and/or enforce drainage plans in replanting consents. WCP to provide alternatives for planting on mineral soils.
- Mitigate with annual sand lime dose
Who?
- NRW through felling and replanting licenses
- WUF
Where?
- Nant y Hwlch, Tywi, Tarrenig and Hafren forests
- 212 sites across acid area
Cost
£32k p/a
Review of efficacy
Add Juettner papers
