Lowland Fens

Importance for wildlife

Pools of open water in the fens can support rich growths of stonewort, which are rather like pond seaweeds, and insectivorous plants called bladderworts with branching roots carrying bladder-like traps to ensnare insects. Fens are home to the great raft spider, which survives in just four sites in the UK. They support many marshland flowers, thousands of invertebrate species as well as a large number of aquatic beetles. Drier areas are home to a wide range of mammals including water shrew and water vole.

Important associated species

Birds
Grasshopper Warbler, Reed Bunting

Mammals
Noctule, Daubenton's Bat*, Nathusius' Pipistrelle*, Soprano Pipistrelle, Harvest Mouse, Water Vole, Water Shrew*

Bees and Wasps
Large Garden Bumblebee, Moss Carder Bee, Fen Mason-wasp

Beetles
Scarce Four-dot Pin-palp, Pashford Pot Beetle, Zircon Reed Beetle

Dragonflies
Norfolk Hawker

Flies
Broads Long-legged Fly, Clubbed Big-headed Fly, Black Fungus Gnat

Molluscs
Little Whirlpool Ramshorn Snail, Shining Ram's-horn Snail, Large-mouthed Valve Snail, Desmoulin's Whorl Snail, Narrow-mouth Whorl Snail

Moths
Water-dock Case-bearer, Concolorous, Grey Dagger**, Knot Grass**, Brown-spot Pinion**, Ear Moth**, Mouse Moth**, Large Nutmeg**, Dusky Brocade**, Garden Tiger**, Minor Shoulder Knot**, Mottled Rustic**, Haworth's Minor**, Crescent**, Small Square-spot**, Small Phoenix**, Double Dart**, Rustic**, Rosy Rustic**, Dot Moth**, Rosy Minor**, Shoulder-striped Wainscot**, Oblique Carpet**, Powdered Quaker**, Shaded Broad-bar**, White Ermine**, Buff Ermine**, Hedge Rustic**, Blood-vein**, Oak Hook-tip (oak trees)**, Sallow**, Dark-barred Twin-Spot Carpet**

Spiders
Rosser's Sac-spider, Fen Raft Spider, Swamp Lookout Spider

Fungi
Frogbit Smut

Plants
Flat Sedge, Early Marsh Orchid (cream), Tubular Water-Dropwort, Greater Water-Parsnip, Marsh Stitchwort

*Suffolk Priority species
**Priority - Research Only. Common and widespread, but rapidly declining

Factors affecting habitat in Suffolk

• Drainage for conversion to intensive agriculture. Past drainage of surrounding areas of land lowering the water table and drying out remnant fen habitats
• Excessive water abstraction from aquifers drying up or reducing spring line flows, lowering water tables and affecting water quality
• Nutrients from agricultural run-off and other sources leading to a change in plant communities
• Afforestation within the catchment areas can lead to drying
• Lack of appropriate management to prevent drying, deterioration in herb richness, scrub encroachment and succession to woodland

Habitat management advice

• Maintain structural diversity: Management rotation ensures longer and shorter vegetation is present at all times. Any natural transition zones between fen and other habitats such as wet woodland, bog, saltmarsh, reedbed and open water should be conserved as some species may require these.
• Retain and create shallow-profiled water margins and ditch-sides and avoid excessive clearance of marginal vegetation. It is important to allow some ditches to become choked as this is needed by a number of specialised species.
• Scrub encroachment should be prevented, but scattered bushes and trees such as sallows provide a valuable resource for invertebrates.
• A reasonably high water level should be maintained, but water levels should be allowed to fluctuate seasonally where applicable.
• The application of fertilisers within the water catchment may have a detrimental effect on water quality. If possible nearby landowners should restrict the use of fertilisers and create buffer strips on adjacent land.
• Grazing should aim to create a diverse structure of vegetation where grasses and herbs can flower and set seed. If a traditional mowing pattern has been in place for a long time it should stay the same, as invertebrates will be well adapted to it.
• Litter piles should be sited in both sunny and shady situations, but not in areas likely to flood, they are important over-wintering sites for many insects. Many species are associated with deep litter layers, so it is important to retain some deep litter.
• Many ground beetles prefer bare ground within fens. Active management such as turf stripping may be required to generate suitable conditions. Small-scale peat cutting to create early succession fen conditions may be essential to provide habitat.

Vision for Suffolk

1. Improve knowledge of extent and quality of lowland fens.
2. Maintain the existing extent of lowland fens to ensure no net loss.
3. Re-create lowland fens as opportunities arise.
4. Encourage the restoration and improvement of degraded lowland fens.

Where to find further information

• Buglife – advice on managing BAP habitats
• Buglife – Notable invertebrates (pdf)
• Fen Management Handbook (pdf) 
• JNCC – Habitat Description (pdf)
• MAGIC website – interactive mapping information including designations
• Making Space for Nature, a Review of England’s Wildlife Sites and Ecological Network 16 Sep 2010. Chaired by Professor Sir John Lawton CBE FRS. Defra website (pdf)
• Natural Environment White Paper June 2011 – The Natural Choice: securing the value of nature (pdf)
• Suffolk Wildlife Trust – Habitats Explorer

* all the links marked (pdf) have been gathered into an Issuu stack

Images: 

• Redgrave and Lopham Fens by Paul Holmen (Flickr)
• Blood-vein moth by Stuart Read (Flickr)
• Greater Water Parsnip by Mark Joy (Flickr)
• Early Marsh Orchid by Stuart Read (Flickr)