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Taking Stock of Changing Broadland. II. Status of Seminatural and Man-Made Habitats

1986; Wiley; Volume: 13; Issue: 4 Linguagem: Inglês

10.2307/2845016

1365-2699

R. M. Fuller,

Pasture and Agricultural Systems

Photointerpretation of aerial photography, combined with techniques of digital cartography, has provided information about the extent and distribution of seminatural habitats and man-made land uses in Broadland. Checks against independent sources of data showed overall map accuracy to be 88?3% (p=0.05), that the simplification inherent in the maps accounted for much of the apparent error, and that the area and line-length data contained minor errors which become negligible in data summaries. Two-thirds of Broadland is intensively used for agriculture; improved pasture forms the larger of the two major components but arable land-area is increasing so that its area now nearly equals that of pasture. One-third of Broadland remains seminatural; waterways occupy 22% of this, though most are eutrophicated, and fens and wet carr-woodlands form the remainder in near equal proportions. Management by cutting and grazing of the fens and marsh grasslands, the richest of Broadland mire com- munities, is inadequate for maintenance of the full extent of these open herbaceous communities. Fens, marsh grasslands, reedswamps and clean waterways, the most important ecologically of the Broadland habitats, occupy only 13% of the flood plains. If carr invades the unmanaged fens, and if reedswamp regression continues at recent rates, in 20 years time there may be only 8% of Broadland which retains these characteristic habitats: even this figure assumes no further reduction in management levels, and no damaging new impacts from land drainage or pollution. The relative scarcity of the ecologically important habitats in Broadland is largely the consequence of inadequate sewage treatment and of rapid agricultural developments in the last half century.