Not All Blanket Bog Is the Same, Says New Environment Agency Report
Quick summary
Environment Agency guidelines divide upland blanket bog into six types according to how water moves through it.
Peat under wet Sphagnum domes averaged around five metres; on heather slopes it averaged 1.2 metres.
The report links degraded bog to past burning, drainage and grazing but tested no management practice.
Sporting estates were hard to access, and the report does not say how much grouse moor was sampled.
On the heather slopes surveyed for a new Environment Agency report, peat averaged 1.2 metres deep. On the flat, sodden domes on top of some basin and trough bogs, where water seeps up underfoot, it averaged around five metres and reached ten.
Blanket bog, the authors argue, has too often been treated as a single habitat. They divide it into six types according to how water moves through and off the peat, and want those types used when sites are surveyed, monitored and restored.
The guidelines are written to underpin Defra's Peatland Standards for restoration, which are still being developed. If they are adopted, the categories in this report could shape the restoration targets set for upland estates.
The report has not been peer reviewed. Sheffield Wetland Ecologists surveyed 62 sites in England and Wales between 2022 and 2025 for this third stage of a project led by the Environment Agency, with Natural England and Natural Resources Wales among the partners.
What the surveyors recorded
At each sample point the team pushed a probe into the peat and listed the plants in a quadrat (a small sample square). They then scored the ground by eye for wetness, softness, Sphagnum moss, heather, pools, tussocks and erosion. Beforehand, LiDAR (laser height mapping flown from aircraft) was used to read the lie of the land.
Most measurements were visual scores on a ranked scale. Peat depth and slope were measured directly, with water acidity and conductivity tested only where there was free water to sample.
The six types came from statistical grouping of 300 of the 473 samples, checked against the surveyors' judgement and drawn cross-sections of each site.
Six kinds of bog
Hill peat: firm, sloping ground with heather and cotton-grass, and the most common type sampled (106 of 438 points). Where the slope eases, flatter patches hold hollows and pools.
Crowns: low domes of very wet, spongy Sphagnum on deep peat.
Aprons: the steeper, usually drier rim around a crown.
Bottoms: firm, deep peat on near-level ground.
Flows: quaking ground with Sphagnum lawns and deep pools.
Water flow tracks: wet channels fed from within the bog or by springs on mineral ground.
Hill peat and crowns each have an eroded form. Where gullies have cut in, the report states, they dry the peat within about two metres of their edge.
A second, looser scheme sorts whole peat bodies by shape: hill bogs that follow the ground beneath them, and deeper deposits held in basins and troughs.
Plants follow the water
The vegetation matched these types closely enough to work as a field guide. Almost half the heather and cotton-grass stands (the M19 community) sat on hill peat slopes.
Around 60% of the Sphagnum-rich M18 community was on crowns. Where M18 formed a continuous spongy carpet, the peat beneath averaged 4.9 metres.
Burning, grazing and the gaps in the evidence
Some deep peat in the survey carried little but heather or purple moor-grass. The report labels this heavily modified and says it usually results from historical damage, naming peat cutting, extensive drainage, frequent burning and heavy grazing. It also notes that many heather slopes are managed as a patchwork of ages for grouse.
That attribution is general. The study measured no management practice and compared no burnt and unburnt ground, so it offers no evidence on the effects of managed burning in either direction.
The sample has a gap as well. Sites were chosen partly for easy access, so many belonged to agencies or conservation bodies. The report does not say how much actively managed grouse moor was included.
What it means on the ground
The Moorland Association's view is that guidance destined to underpin national restoration standards should be tested on working moorland by the people who manage it. Among their proposals for further work, the authors list training days and encouraging practitioners to try the method on sites they know. Members can take them up on it.
The kit is cheap. A LiDAR map, two survey lines at right angles and a peat probe cover most of the work, and the authors point out that electricians' rods make a serviceable probe. Anyone who knows where their hill holds water after a wet week can judge whether these six types describe it, and help close the gap on managed grouse moor.
Key Takeaway
Peat under Sphagnum domes averaged about four times the depth found on heather slopes, and guidance built on that difference should now be tested on working moorland.
