To the uninitiated a vertical mulcher might sound like the creation of a feverish nightmare, but the tree-chipping machine might be the saviour of one of the UK’s most important peat habitants.
The mulching is a continuation of a 50-year project to restore the Border Mires, a network of bogs in and around Kielder Forest in Northumberland that dates from the ice age. Forestry England will use the nine-tonne timber harvester to munch through 23 hectares (57 acres) of trees in order to speed up restoration of the mires.
The Border Mires started to form around 12,000 years ago when the last glaciers retreated from northern Britain. The impenetrable bogland became famous for harbouring cattle robbers known as the “moss troopers’” in the 17th century.
Although planting trees is more often associated with combatting climate change, ecologists say that removing trees and restoring the mire play a crucial role in mitigating its effects. Many of the mires were partially planted as part of a drive to shore up the nation’s timbre reserves, depleted after two world wars. However, this lowered the water table and dried out the top peat, affecting the rare plant communities.
Wayne Penrose, a Forestry England ecologist who is overseeing the work on the ground, said that removing the trees and blocking drainage channels raises the hydrology levels and restores the mires, which then act as “a massive carbon store”.
Penrose and his team will use the vertical mulcher, which has a powerful cutting disc that spins at high speed to turn tree trunks into chips. Because the ground is so soft, it has been fitted with one metre-wide tracks to keep it “afloat” during the vital work. The project, which began in September and is due to be completed by the end of the month, will mulch trees on one of the Border Mires known as Rabbit Crag, near Falstone, Northumberland.
They will also remove smaller spruce with chainsaws at three other locations, covering 161 hectares, and blocking 3.5km (2.2 miles) of drainage channels so the land retains water, the so-called lifeblood of a bog.
The mires, which Penrose describes as “great, big, botanical, living, breathing things”, support an array of plants and wildlife including sundews – a carnivorous plant akin to a Venus flytrap but with the tentacles on the outside – bog cranberries and bog rosemary, a smaller version of the common herb grown in gardens.
The restoration work is also designed to boost one of England’s rarest trees: the bonsai-like dwarf birch, usually found in much colder climates.
Also found on the Border Mires are sphagnum moss, dragonflies and wading birds, although nature lovers need to take care as the bogs are “fairly treacherous”, according to Penrose. In places, the peat is up to 15 metres deep. The Border Mires hold more liquid than Kielder Water – Europe’s largest man-made lake.
Angus Lunn is vice-president of the Northumberland Wildlife Trust, the group of volunteers that installed the first peat dams in drains in the Border Mires, armed only with spades, 50 years ago.
“Some people may think bogs are not as beautiful as ancient woods or rainforests, but they are an incredibly valuable habitat and part of a rich mosaic of landscapes in Kielder Forest,” he said.
The project is being carried out under the guidance of the Border Mires Management Committee, a collaboration of several partners including the Ministry of Defence – some of the mires are situated near RAF Spadeadam – Forestry England, Northumberland Wildlife Trust, Natural England, Northumberland National Park Authority and the University of Newcastle upon Tyne. Defra has provided £175,000 of funding.