Waveney and Little Ouse Valley Fens IPA

Location: Norfolk/ Suffolk Border between Diss and Thetford

Grid Reference: TM 047 799

Waveney & Little Ouse Valley Fens IPA has been recognised as one of 165 Important Plant Areas in the UK.

The key features of this IPA are:

  • The species richness of vascular plants in base-rich fens
  • The species richness of stoneworts in base-rich fens
  • One of the best UK examples of threatened habitats of:
    Calcareous fens with Great Fen Sedge;
    Purple moor-grass meadows
  • The river corridor straddling the upper reaches of the Little Ouse and Waveney rivers once held the most extensive area of valley fen in England.

    Valley fens have suffered a dramatic decline throughout Europe because of drainage and people's use of water. In the UK there are only 43 valley fens left. Of all eco-systems in the UK, fens are one of the most valuable botanical resources, with a large range of plant species, including many that are uncommon and declining and several that are already rare. The origin of the valley fens goes back 300,000 years to the last ice age when the glaciers carved what are today the Ouse and Waveney Valleys.

    The localised extraction of peat has led to the creation of open water within the sedge beds, and these pools have been colonised by a variety of stoneworts ( a key feature of the Broads IPA).

    Reeds are usually the first plant to become established in a lake or pond, and tend to dominate, forming dense patches in nutrient-rich peat or mud. Plants which do grow amongst the reed are greater willow herb, meadowsweet, marsh marigold and nettle. Reed grows abundantly in these fens and was once the most valuable crop here, since it was considered the best material for thatching. Saw sedge flourishes in the chalky water areas. The water is low in nutrients so no single species can grow vigorously enough to dominate and there is an excellent mix of plant species (e.g. meadowsweet, rushes, spearworts and ragged robin).

    Some areas at the margins of the chalky areas were in the past cut for fen hay. Several species of orchids grow here, such as the early marsh and marsh fragrant. Another unusual plant found here is the bladderwort, which has adapted to become carnivorous, this plant can trap and digest tiny pond animals, which means it does not need to get nitrates from the soil or water.

    Where the fen has dried out sufficiently, swampy woodland, known as ‘Carr’ has developed. The principal tree species here are aspen, alder and birch. Fewer different plant species grow here than in fen, but where the light can still penetrate, plants such as marsh marigold thrive in pockets of wet soil.