Lowland fens

Lowland fens produce very colourful displays of wildflowers such as meadowsweet, valerians, globeflowers, bogbean, water avens and scabious between June and August. These fens typically occur in flat (valley-bottom) situations and are fed by naturally nutrient-rich ground-waters.

The UK is thought to host a large proportion of the fen surviving in the EU with the base-poor fen at Insh Marshes in Scotland, the calcareous-rich fen and swamp of Broadland, the extensive areas of the Lough Erne system in Fermanagh being three important examples.

In the Dales, lowland fens are an important and very scarce habitat. The fragments of rich fen that remain, most notably on the Malham Tarn NNR and at places like Helwith Moss in Ribblesdale support an extremely diverse flora and fauna including an impressive array of rare and scarce species like the narrow small-reed, montane eyebright, lesser tussock-sedge, fibrous tussock-sedge, dark-leaved willow and invertebrates including a rare leaf beetle and scarce craneflies, hoverflies and a soldier fly. The lowland fen habitats support a real diversity of specialist species as well as being vital feeding or breeding areas for a number of birds and other animals that also use other habitats.

At risk?

In the Dales, lowland fens are arguably the habitat that has been most reduced by human activity over the centuries.  Even with the widest definition of lowland fen, they now cover less than 1.5% of the Dales!  This can be compared with the more intensive agricultural grassland that covers nearly 30% of the Dales and which has been largely been converted from the fen, wet grassland and wet woodland/scrub that would originally have covered the valley bottoms and lower valley sides.  Lowland fen has suffered these drastic losses because it is relatively easily drained and can be converted to productive grassland with the use of fertilisers. The fragmentation of lowland fen is already a serious concern with populations becoming small and isolated and highly susceptible to local fluctuations and extinctions. It is important that we not only conserve the remaining areas but work with farmers and landowners to restore more of a patchwork of fen across the Dales.

The unfolding of Grass Wood throughout the year is a story of rich fulfilment. From 'Wharfedale' by Ella Pontefract & Marie Hartley

Facts at your fingertips