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Upland Flushes, Fens and Swamps

  1. Habitats explorer
  2. Wetlands and rivers
  3. Upland Flushes, Fens and Swamps

Upland Flushes - Cotton grass - Clare and BenUpland Flushes - Cotton grass - Clare and Ben

What are they?

The wet, boggy areas that ooze from our dramatic hillside landscapes are upland flushes, fens and swamps. Like blanket bog, they are often peaty or mineral-based, but they are not entirely rain-fed – they get most of their water from the surface and groundwater. The water table in these areas is close to or above the surface for most of the year.


Fens are characterised by their plant communities; marsh is a general term usually used for waterlogged soil, while swamps are dominated by tall emergent vegetation and have a higher water level for most of the year. Flushes are associated with water moving through the soil, and springs with localised upwelling of water.


Typically, these wild places are grazed by deer, sheep, or sometimes cattle as they are often part of a surrounding heath or grassland. A varied habitat, sedges, rushes and grasses spike the ground, living carpets of sphagnum moss create a spongy base and wetland flowers pepper the browning landscape with hints of colour.

Where are they found?

Upland flushes, fens and swamps are widespread, but localised, throughout the uplands of Scotland, Wales, England and Northern Ireland.

Why are they important?

A variety of plants wallow in the swamps around the margins of ponds, lakes and slow-moving rivers including reed canary-grass, water horsetail, common spike-rush and common reed. Reeds also grow in fens alongside tall herbs, sedges and sphagnum mosses, as well as cross-leaved heath and bog asphodel.


Acid flushes are generally species-poor and are characterised by bog-mosses, small sedges and the waving white heads of common cotton-grass. Base-rich flushes with a high pH form over calcareous areas and are more diverse with a range of mosses and liverworts taking hold, alongside small sedges, the nationally scarce bird’s-eye primrose, insectivorous butterwort and sprawling autumn hawkbit.


Springs are generally dominated by mosses and liverworts, with starry saxifrage, opposite-leaved golden saxifrage, lesser clubmoss and autumn hawkbit present. Springs and flushes also harbour uncommon plants like alpine bartsia and marsh saxifrage.


It’s apparent that upland flushes, fens and swamps are rich and varied in their make-up, supporting many rare plant species such as scorched alpine-sedge, mountain scurvygrass, two-flowered rush and false sedge. These habitats are important for nesting waders, such as curlew, snipe and redshank, and support a range of invertebrates from dragonflies to butterflies. They can also provide important homes for otters, water voles and other threatened mammals.

Are they threatened?

Upland flushes, fens and swamps are threatened by overgrazing which can lead to the loss of more fragile plant species and the spread of rank vegetation. In extreme cases, heavy grazing and trampling can lead to the exposure of bare soil and subsequent erosion. As a result, the insects and other animals these plants support have been lost in many areas.


Our upland habitats are also vulnerable to drainage, mineral and peat extraction, afforestation and heavy recreational pressure.

How are The Wildlife Trusts helping?

The Wildlife Trusts are working to prevent further loss of our upland flushes, fens and swamps by looking after areas of upland habitat as nature reserves. We use traditional management techniques, such as grazing, to maintain them, and in some places we are restoring areas of habitat that have deteriorated. Several Wildlife Trusts also provide advice and guidance for landowners and farmers on wildlife-friendly farming practices for upland habitats.

What can I do to help?

  • Take part in conservation measures on your land – ask The Wildlife Trusts for advice on grazing and management of upland flushes, fens and swamps if these habitats occur on land that you own.
  • Across the UK several Wildlife Trusts are actively involved with the conservation and restoration of upland habitats including flushes, fens and swamps – you can support the work of your local Wildlife Trust by becoming a member.