The headwaters of the Little Ouse and Waveney rivers formed on a flat landscape with very slow drainage resulting in a watery landscape that includes the largest surviving valley fen in England at Lopham & Redgrave. Glacier-cut valleys are filled with chalk, clay, sand and gravel and of course water! Over time thick layers of peat developed which, depending on the underlying deposits, are sometimes acidic and sometimes lime-rich. These fens are a rare habitat in the UK (and indeed internationally) and are home to special wetland plants like Bladderworts and Marsh Orchids
During the day we’ll visit three of the most biodiverse valley fens. We’ll start at the largest, Lopham & Redgrave. Here pools of open water can be clothed with Duckweeds and often support rich growths of stonewort. Edge communities are dominated by sedges such as Great Fen Sedge as well as flowering plants such as Great Willowherb, Spearwort, Meadowsweet and Marsh Marigold. This is also the home of the Great Raft Spider, Britain’s largest spider which survives in just four sites in the UK. Fens support many lovely plants including the rare Narrow-leaved Marsh Orchid. Marsh Lousewort provides splashes of purple. In slightly drier turf on the most calcareous ground are meadows dominated by Purple Moor-grass, but amongst this grass are many special plants including Meadow Thistle, Ragged Robin and Black Bog-rush. There’s also an array of orchids such as Fragrant Orchid, Early Marsh Orchid and Southern Marsh Orchid. Grasshopper Warblers reel away from bushes in these meadows, whilst in the wetter areas of the reserve we can expect to see Reed and Sedge Warblers and at least hear Cetti’s Warblers. Hobbies often hunt over the reserve especially when Odonata are abundant.
Next we’ll visit Market Weston Fen. This mosaic of fen, heath and woodland with abundant ponds is a great site for Odonata generally and is home to the White Admiral. Purging Flax, Common Gromwell, Common Water Crowfoot, Water Dock and perhaps strangely the more usually Mediterranean Milk Thistle thrive at Market Weston. Common Spotted Orchids, the ochroleuca form of Early Marsh Orchid and the robust densiflora form of Fragrant Orchid will be in bloom, as will be Twayblade and the lovely Marsh Helleborine. Sedges are diverse with Cladium mariscus, Carex paniculata, Carex muricata, Carex distans and Carex pulicaris. They are even more diverse at out next site, Thelnetham Fen, with Eriophorum angustifolium, Schoenus nigricans, Carex otrubae, Carex disticha, Carex remota, Carex hirta, Carex acutiformis, Carex panacea, Carex lepidocarpa, Carex nigra and Carex elata all to be seen. Here is another form of Early Marsh Orchid as well as Southern Marsh Orchid, Pyramidal Orchid and again, the lovely Marsh Helleborine – who could ever tire of this plant? Marsh Valerian, Lesser Spearwort, Common Meadow-rue, Square-stalked St John’s Wort, Common Skullcap, Marsh Cinquefoil, Marsh Pennywort, Water Chickweed and the lovely little Brookweed give some indication of just how rich this fen is!
The whole natural world!