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| Breckland |
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| Habitat: Fens (of national significance) |
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These are peatlands which receive water and nutrients from the soil, rock and ground water, as well as from rain. The vegetation is often low-growing, dominated by sedges, rushes and occasionally bog mosses.
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In the headwaters and tributaries of the Little Ouse, Lark, Wissey and Thet are spring-fedwetlands, known as valleyhead fens or headwater fens, which depend on this nutrient-poor,chalky, water. The emerging springs or seepage lines percolate through thin peat layersmaking this alkaline too and virtually permanently wet underfoot. The vegetation of theseepage slopes is characterised by black bog-rush and blunt-flowered rush with marshmarigolds, fen bedstraw and the late summer-flowering devil's-bit scabious, as seen at GreatCressingham Fen, Thompson Common and Gooderstone Fen in Norfolk and Weston Fen inSuffolk. Fen meadow vegetation is also typical with purple moor-grass, blunt flowered rushand a host of flowering plant species whose ‘marsh' names indicate their love of a high watertable - species such as marsh valerian, marsh pennywort, marsh lousewort and marsh orchids.
The aptly named hacksaw-leaved saw sedge forms extensive beds in Talent's Fen on FouldenCommon and at Swangey Fen on the edge of the Natural Area. Saw sedge is a component ofthe tall fen vegetation in many valley-head fens, together with common reed and lesser pondsedge.
All these fen types are rich in insects, especially water beetles, snails and fly species. Reedand sedge warblers are typical breeding birds. Grass snakes can be fairly common too,doubtless feeding on the frog populations of the ditches and dykes. Sites like Weston Fen arehome to large numbers of dragonflies and damselflies.
Little remains of the formerly extensive fens on the Breckland/Fenland boundary. PashfordPoors Fen and Lakenheath Poors Fen are two that have survived with their mosaics ofspecies-rich fen meadow and wet grassland. Fen vegetation also occurs in the river valleyfloors, for example between Thetford and Brandon and undoubtedly receive somegroundwater in places from the edge of the sands.
The fens are often abandoned pasture or mowing meadow characterised by tall vegetation ofreed, reed sweet-grass or pond sedges and greater tussock-sedge, with nettle, willowherb andmeadowsweet on drier ground. These fens have typically been planted with poplars, as seenextensively on the Little Ouse and Lark. The largest reedbeds, away from the spring-fed fens,occur in association with man made lakes such as Stanford Water, and also beside the LittleOuse at Horse Meadows. Sallow and alder carr has invaded many former fen sites, but arange of mixed ash/alder, willow/alder and pure alder carrs exist depending on land usehistory and wetness. Several alder carrs have been coppiced for fuel over long periods. Typical plants include water mint, bugle, water avens, gipsywort and occasionally bogbean. All these carr woodlands are poorly described and will pay much further attention fromnaturalists.
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