Securing Biodiversity in Breckland - European Commission

The area of grass-heath declined by 76% within the 20 th century:1900: 28,932 ha1934: 31,922 ha1950: 9,268 ha1980: 4,529 ha 11990s: c 7,000 ha 21estimated by Farrell (1993)2 the Natural England Natural Area Profile estimate of grass-heath extent is 2,471 ha greater,as it also includes more recent reverted arable within STANTA in the estimate of the currentresource.Changes in Fen, Wetland and River Valley habitatsFens were once extensive along the Breckland/Fenland boundary but have been almost entirelydestroyed. Mosaics of species-rich fen meadow and wet grassland survive at Pashford Poors Fenand Lakenheath Poors Fen, for example, but these are small fragments of formerly extensive fenand wet grassland reclaimed prior to the 1940s. Reclamation of further areas on the fen edgeoccurred with the Great Ouse Flood Protection Scheme post-1950s (Rothera 1989). Remaining sitesare detrimentally affected by adjacent drainage and are vulnerable to groundwater abstraction(Rothera 1998).The spring-fed valley fens have been vulnerable to drainage on adjacent farmland, subsequentdrying out and scrub invasion. Abandonment of traditional grazing, and/or cutting of reed, sawsedge and peat fuel during the 20 th century led to willow and alder scrub invasion and a loss ofwildlife value in remaining Breckland fens (Rothera 1989). Pingos, the relict peri-glacial waterbodiesthat hold important fen and invertebrate communities, occur at high densities within Breckland(Walmsley 2008), but have suffered loss through agricultural improvement and afforestation. Theremaining pingo sites have also been subject to scrubbing up and succession to woodland, withresulting shading and organic mud accumulation from leaf litter as a result of a lack of grazing afterthe 1940s (Rothera 1998).The rivers of Breckland and their adjacent wetlands have experienced substantial change andmodification. Channel engineering works altered the course and profiles of rivers from the 17 thCentury through to the 1970s (Rothera 1998). Reclamation for agriculture and subsequentimprovements led to a substantial loss of adjacent wetlands, such as wet grassland and fen,especially along the shallower valleys of the Wissey and the Lark (Rothera 1998). However, someriver valley wetlands have survived, with concentrations of County Wildlife Sites on the Little Ousedownstream of Brandon and on the Lark near Cavenham, for example. However, these are oftenmuch altered, being drier, more fragmented and less species rich than a century ago. W G Clarkedescribed redshank and snipe in nesting wet meadows, but these are now absent from Breckland asbreeding species.As with the spring-fed fens, the abandonment of traditional uses of riverside resources has led tothe development of sallow car and wet woodland. The planting of poplar in Thetford Forest alongthe Little Ouse has altered the character of the riverside fenlands. However, as these plantationsare abandoned and decay a rich mix of open fen, carr and standing dead wood is developing. Amore intact series of riverside habitats has been preserved along the Wissey in STANTA.17