Description
Woodwalton Fen is a rare and isolated remnant of fenland habitat lying at the lowest most westerly point of the East Anglian fens. It’s one of few remnants to survive the large scale drainage for agriculture between the 17th and 19th century which saw the loss of almost all the wetland habitat in the wider area.
It was one of the first National Nature Reserves to be established in the UK, being created in 1919 by Charles Rothschild who went on to create what are now know as the county wildlife trusts. Woodwalton Fen NNR is now at the heart of the Great Fen Project which aims to link it up with Holme Fen NNR.
The site, once a raised bog, was dug for peat in the late 19th-century when most of the acidic peat was removed, exposing the underlying fen peat. The vegetation of the area today largely reflects this historical use of the site. Woodwalton Fen holds a range of wetland plant communities once characteristic of large areas of the East Anglian Fens, but which are now restricted to a small number of isolated examples in Cambridgeshire, Suffolk and Norfolk. In addition, two meres have been dug in order to increase the area of standing water on the site, and these have proved valuable for aquatic plant and animal communities. Further habitats of significance on the site include marshy grassland,
Habitats
Fen, mire and swamp
There are some open fen and swamp communities that are a relics of the acidic peat bog moss where heather, bog myrtle and great fen-sedge are found. Floristically rich mixed fen covers most of the site and contains species such as common meadow-rue, yellow iris, swamp meadow-grass and water dock. Rare fen plants such as fen wood-rush, and fen violet also occur.
The network of ditches on the site hold many water plants which are now relatively uncommon in Britain including greater bladderwort and water violet.
Open Water
The open water habitat on the reserve is a very important feature supporting many specialist plants and invertebrates. The ditch system criss-crosses the whole reserve keeping the water table high throughout the year and supporting an abundant flora including lesser and greater water parsnip, frog-bit, bladderwort and greater water dock.
The larger water bodies of the meres are home to many bird species including coot, mallard, little grebe and cormorant, and these are joined in the winter months by overwintering species such as wigeon.
Reedbed
The reedbed in the north of the reserve is kept wet all year round by pumping water in and out using a wind powered pump. This area has a good population of breeding sedge, reed and grasshopper warblers. Marsh harrier also nest in the reedbed and bittern use this habitat particularly in the winter.
Grassland
The ride edges, marshy grassland and mixed fen are home to some of our nationally important plants such as fen ragwort, fen violet and fen woodrush. The marsh sow thistle, a fenland specialist, towers along the rides at up to 8ft tall. Abundant butterflies are seen along the rides; this reserve was the last stronghold for the large copper butterfly which is now extinct in the UK, despite efforts to reintroduce this wetland species.
Wet woodland
The wet woodland or carr is mainly composed of birch, alder and willows and oak, ash, blackthorn and guelder rose are also present.
The woodland is a fantastic habitat for many invertebrate species and also many species of fungi, moss and liverwort.
Deer are common throughout the reserve and include the Chinese water deer as well as the muntjac deer. Chinese water deer are an introduced species but ironically the UK now has a globally important population as they are threatened in their native China.
Key species
Fen and open water plants
Of the 490 species of plant that have been recorded, the fen plant community is the most important. Species of conservation concern include: narrow-leaved marsh orchid, needle spike rush, water violet, lesser water plantain, fen woodrush, fringed water lily, marsh lousewort, three nationally rare pond weeds, fen violet, and greater water parsnip.
Fungi
The wet woodland habitat is particularly rich in fungi and 482 species have been found on the reserve to date. Two species of note are the reed bonnet that grows on the submerged bases of common reed and angel’s wings which is a rare pure white type of oyster mushroom.
Breeding birds
Important breeding birds include marsh harrier, turtle dove, lesser spotted woodpecker, willow tit, corn bunting and spotted flycatcher. Bittern regularly overwinter on the site and are increasingly heard in the spring.
Common crane are regularly seen on and around the reserve and may become a breeding species in the future.
Barn owl and long eared owl are resident on the reserve and large flocks of fieldfare arrive in winter to feast on the hawthorn berries.
Migrant hawker
The site has an immense list of invertebrates with over 1000 beetles alone. Butterflies and moths are not far behind at 953 species of moth and 45 species of butterfly.
Rare species include the marsh carpet moth, a vulnerable species completely dependant upon the growth of common meadow-rue .
It is an exceptional site for dragonflies and 19 species can regularly be seen, including migrant hawker and scarce chaser.
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Grass snake
Grass snakes are seen regularly, and common lizard, frogs and toads also use this wetland site.
The grass snake is the UK’s largest native reptile, and is entirely non-venomous and very shy. Their main defence, if cornered, is either to play dead or release a foul-smelling musk.
Harvest mouse
Water vole and otter use the wetland habitat and harvest mouse, Britain’s smallest mouse, make their nests in the tall vegetation.
Further info
Cambridgeshire NNRs:
https://www.greatfen.org.uk/woodwalton-fen
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