Dartmoor's bogs are drying out

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DARTMOOR IS drying out. One of our last upland wildernesses is under serious ecological threat as years of landscape abuse take their toll with wide-reaching implications for plant, animal and human life.

The moor's protective top layers - a blanket bog underlain with a seam of peat - has always been an excellent water retainer - "nature's sponge" locals call the moor - but the combined efforts of over-grazing of cattle, over-burning and prolonged use as a military firing range have all torn swathes of skin from the moor's back.

On certain parts of the moor, especially in the east and south where the high country rolls off to the coastal plain, the scars are starting to show. Harford Moor is one patch being watched with particular interest.

Dartmoor is an internationally important habitat and the flora and fauna that live there are under threat as their sustaining bog disappears. As well as the cattle, sheep and the moor's famous ponies, it is a vital nesting sight for dunlin (only a handful of breeding pairs remain), and home to bog orchids and several species of rare dragonfly, including the keeled skimmer.

Local people have gone on about the moor drying out for years. Many say parts which were once off-limits to horse-riders for fear of the bog swallowing them up are now solid dried peat that will take the weight of the heaviest horse. The first scientific evidence, however, is just emerging.

Andrew Williams, a reader in soil and water management at Plymouth University, andErik Meyles, a PhD student from the Wageningen Agricultural University in the Netherlands, have found the speed at which rainwater is running off the moor has increased, so less is soaking into the peat. The result is drier, less healthy upland and more risk of flash floods in the rivers that rise on the moor. These include the Dart, the Teign and the Taw.

But the scientists have found something else which is adding to the problem.

"If you remove the heather or change the vegetation, the soil temperature will increase by one or two degrees as it is being subjected to more direct sunlight and there is less organic matter to retain moisture," said Dr Williams.

With such tinder-dry conditions, over-zealous burning, or "swaling", by well-intentioned farmers has had catastrophic results. As Dr Rob Wotton of English Nature explained, farmers frequently burn parts of the moor to clear dead grass and allow new growth, and utilise the ash as a natural fertiliser, "but unfortunately it has been unregulated and unplanned".

No one is pointing the finger of blame for the state of the moor but an urgent review of agricultural practices among the moor commoners (those who have rights to farm privately owned land) is being drawn up. Between 1952 and 1994 the moor beef herd increased 10-fold to 20,000 and the numbers of ewes increased three-fold to 132,000.

Even the Commoners' own representative, Professor Roy Brown, an expert in countryside management, admitted things must change.

"There has been serious over-grazing and it has to be dealt with," he said. "Once these lands dry out they do not always re-wet easily. Instead they dehydrate, so it's not just a matter of pouring water back in and hoping everything will be all right. It is probably a one-way process."