Layers of Time – A Moorland Conservation Story

16 Mar

Peat deposition on moorland is known to be one of the most effective forms of carbon storage, or ‘sequestration’. In its undisturbed state, peat is also a haven for unique and important wildlife but, around this priceless landscape lie layers of history and stories of human endeavour. Prehistory has been captured where the earliest farmers left signs of stone enclosures on Dartmoor that gave way to medieval field systems and villages. In one particular windswept spot, high above Ivybridge, the first years of industrialisation have also left their legacy. Tin mining has been well documented and tracks to bring in coal to power machinery are still visible on the ground. Later, there were further tracks built to access china clay with a pipeline several miles long to transport the valuable china clay slurry off the moor for processing. After that, drainage ditches were cut to create areas more suitable for grazing sheep to provide wool. All this, combined with peat cutting to supply fuel for local homes has left signs of the farming and industry that has gone on for hundreds or thousands of years.

Each time, this human activity has contributed to an overall radical change to the moorland habitat, much of it is a malign legacy in ecological terms. But if you travel there today (under your own steam along the old Puffing Billy track) you may see a different picture. The industrial relics are still there as a few recognisable landscape features in the remote and bleak moorland over 6 miles out from the moor gate near the south Dartmoor village of Bittaford, but around them, peatland restoration is our latest effort to push back against detrimental human actions.

Historical china clay excavation surrounded by heavily drained moorland

Derelict china clay workings at Red Lake and drainage channels beside the old Puffing Billy track bed [Devon CC Environment Viewer]

Quantock and Exmoor Ltd., a southwest company that, among their various ecological management roles, specialise in natural flood management. Andy Coleman, the company manager explained that “Following the original University of Exeter condition mapping of the moor, we are inserting blocks in the eroded channels that were created by these old industries, peat cutting or land drainage. Using GPS locations, we are building thousands of these blocks and can plot their precise location.”

Andy’s team of machine drivers have been working on this area for several weeks after moving over from other areas on Dartmoor. Their aim is to create dams that hold back water that previously rushed down the channels and into the rivers. Some of these structures are small peat and turf mounds that prevent water flowing downhill and, where possible, push it sideways to create broader, wetter areas. The skill of these drivers is evident as they sculpt small mounds with a ‘tilt-rotator head’ on the digger arm, leaving the turf covered dams to be assimilated back into the moorland landscape. The machines are specialised for this work in sensitive habitats. To reduce damage, each one is fitted with wide tracks to spread the load. Though they are heavy machines, each one only applies a maximum of 3 pounds per square inch to the soft ground beneath.

Industrious moorland restoration in progress

Using GPS for precise ditch blocking

Other blocks are made from timber extracted from local conservation woodland management. These may remain visible as timber boards or can be covered with peat. The design of each dam depends on the depth and condition of the surrounding peat. Andy explained, “We never leave bare peat on the surface as this will erode and lead to more carbon being released or eroded particles entering the watercourses.” Even though the winter weather can be hostile on the high moor, Andy was undeterred and, reflecting on the many generations of past workers he said, “We have to consider all the ages of archaeology and it helps to be interested in the history of this place - we are just adding our layer of history onto the moor.” Heading further along the old Puffing Billy track to the derelict Red Lake china clay works, Andy pointed out where parallel drainage channels were being blocked with a row of small dams, pointing out how they capture a night of heavy rain. “You can see how well they are working and how quickly they fill up”, he added.

Andy demonstrates the immediate effectiveness of the moorland restoration process

Timber dams are used where there is not enough peat and turf

This part of the region-wide project is focussing on the River Erme catchment, one the many rivers that start their life on Dartmoor. Other river systems have already benefitted, particularly the Dart and its tributaries, and there will be more to come. Moorland conservation is not only at work across Dartmoor but other uplands of the region too. The South West Peatland Partnership is working to restore damaged peatland on Exmoor, Bodmin Moor and other areas of Cornwall. The latest £7m grant for this work to slow the flow of water leaving the high moor is going well, re-wetting the moor, improving the growth of peat bog vegetation, allowing the atmospheric carbon to be captured in the new layers of peat and improving water quality. The simple act of blocking erosion channels also reduces the troublesome purple moor grass and boosts the overall biodiversity including nesting birds and invertebrates on the moor. All in all, peat restoration is a benefit to both wildlife and people and, in financial terms, the investment should provide value for money as it will reduce flooding in towns and villages downstream. The project is led by Morag Angus, South West Water’s Mires Partnership Manager.

Timber blocks restoring moorland ditches

Timber material for this task is supplied from the most local of sources including Woodland Trust sites at Ausewell Wood, Bovey Valley and Fingle Woods via a chain of local enterprises. One of the Woodland Trust sites at Hall Farm is close enough to be visible from the Puffing Billy track on the other side of the River Erme. White Wood Management who milled the timber and Martin Underhill Forestry are typical of the small local businesses that play a vital role of connecting the conservation work in Dartmoor woodlands with the moorland restoration project.

Round wood timber has been used instead of slotted boards in some locations where the surface depressions are shallow and wide. These large logs are heavy to move on the moor but will last for many years, or even centuries when buried in peat.

Low quality roundwood timber makes a perfect shallow dam when covered with peat [photos: Andy Coleman]

The positive effect of conservation is described on the South West Water website:

“The moors of Bodmin, Dartmoor and Exmoor hold significant regional and national deposits of peat in the form of blanket bogs and valley mires. These wetland habitats are complex ecosystems that support diverse and unique ecology of national and international importance.

Over centuries, human interventions have and still are impacting upon the overall quality and distribution of wetland mire habitats and upland moors. The demise of such wetlands across extensive swathes of the moors has resulted in changes in the moorland ecology, including the loss of iconic species such as dunlin, golden plover, and Sphagnum mosses.”

by Matt Parkins

More information about the work of the South West Peatland Partnership can be found here:

South West Peatland Partnership (southwestwater.co.uk)

Other interesting webpages detailing local industrial heritage:

red lake china clay workings – extraction – Dartmoor Explorations

dartmoor