Soil Erosion: An Advisory Leaflet for Preventing Soil Erosion in the Uplands (PB5820a)

Soil Erosion: Preventing soil erosion in the uplands

PB5820A
2001, rev. 2005

 

 

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This chapter shows how the uplands are at risk from erosion and advises on land management practices that help to give protection.

Uplands and erosion

The uplands are an internationally important habitat for wildlife and are also used for agriculture, recreation and sport, and for water collection and mineral abstraction.

The uplands are very susceptible to erosion because of their climate, soils and landscape. Today, this risk of erosion is very high because of increasing use of the uplands.

A complete vegetation cover protects fragile upland soils from erosion by water and wind. Erosion begins when vegetation is removed for example by burning, overgrazing or traffic, and bare soil is exposed to rain and wind. Erosion is most severe on peat soils and steep slopes, where it may take years for the vegetation to recover.

Consequences of erosion

Upland erosion not only results in soil loss:

  • Stock carrying capacity is reduced.
  • Loss of vegetation increases grazing pressure on the remaining vegetation.
  • Eroded landscapes are less attractive to visitors.
  • Rare plants and animals that cannot survive in eroding landscapes may be replaced by more competitive species.
  • Eroded soil may end up in reservoirs where it reduces water quality and storage volumes.
  • Fish stocks may be threatened as sediment suffocates eggs laid in streambeds.
  • The risk of flooding increases as rainfall is no longer retained by the soil and instead rushes into streams and rivers.

Traffic

All upland traffic, whether due to grazing animals, humans or vehicles, may damage vegetation and expose the soil to erosion.

To minimise the risks of erosion through traffic:

  • Use management practices that minimise the need for vehicle use.
  • When vehicles are necessary, use low ground pressure machinery.
  • Restrict vehicle use to dry periods and to gentle slopes.

  • Keep to established tracks and paths to avoid vegetation damage.
  • Plan track construction and maintenance carefully, paying particular attention to position and drainage to minimise run off.
  • Maintain gates and stiles and way-mark paths to restrict damage caused by walkers.

Grazing

Overgrazing by domestic or wild animals breaks up vegetation cover and once the soil is exposed, the grazing area is reduced and the soil can erode. Recent changes in government support in the uplands should encourage reductions in stock numbers. Erosion is common where stock gather in large numbers in a small area, such as for supplementary feeding.

  • Shepherd animals to ensure the entire grazing area is used and to prevent localised overgrazing.
  • Place feed racks 250 metres away from sensitive vegetation and preferably on level ground with a cover of coarse grass or dead bracken.
  • Place feed supplement blocks 250 m away from feeding sites already used.

Additional measures must be undertaken on land designated as a Site of Special Scientific Interest or held within any agri-environmental scheme.

Burning

Heather, purple moor grass and mat grass are frequently burned to encourage new growth for grazing and grouse moors. Correct timing is essential to avoid damaging young vegetation and the risk of uncontrolled fires on older vegetation. Incorrect or ill-planned burning can cause long-term damage to the underlying soil and so result in extensive erosion.

Careful planning is the key to successful heather burning

  • Burn in small areas for greatest benefit and safety.
  • Avoid steep ground, wet blanket bog and deep peat where loss of vegetation can cause serious and rapid erosion.
  • Most benefit is obtained by burning heather on freely-drained, gently sloping ground.

Further advice on burning is contained in the Defra Heather and Grass Burning Code.

Bracken control

To avoid erosion caused by removal of bracken, a bracken management plan can help to avoid bare areas and result in the establishment of a good cover of diverse vegetation.

  • Avoid steep slopes.
  • Avoid leaving bare areas.
  • Look for evidence of grass or other vegetation under bracken.
  • Do not remove bracken if other vegetation is unlikely to establish.

Moorland drainage/gripping

Grips are small ditches dug at regular intervals over moorland to improve heather growth. By allowing the faster and channeled loss of water, grips encourage peat erosion. As soil is washed away, grips can develop into large, unsightly and hazardous gullies.

Where erosion is occurring:

  • Do not maintain existing grips and do not dig new ones.
  • Block existing grips wherever possible.
  • Remove a block of peat from near the grip and push it into the grip to form a dam, keeping the vegetation at the top.
  • Use a 360 degree tracked excavator with wide (“Bogmaster”) tracks.
  • Straw or heather bales can also be used to form dams but are generally less effective and not readily colonised by surrounding vegetation.
  • Dams should be built up to the level of the adjacent ground and be 2-3 times the width of the grip in length. The spacing between dams depends on the slope of the land.

  • Large grips can be blocked with timber or plastic piles.
  • Specialist advice should be obtained, before blocking grips, for example from ADAS, English Nature or FWAG.

Grants may be available for grip blocking. If you farm on an SSSI or have an agri-environment scheme agreement, seek advice from English Nature or Defra Rural Development Service before doing any grip blocking.

 


 

 

DEFRA PB5820A, 2001, revised 2005
(C) Crown Copyright. Reproduced for ADLib under Licence.

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