For a private company

Maydencroft was commissioned by a water company to undertake river restoration tree surveys of sections of rare chalk streams in the southeast of England. The survey covered sections of the following chalk streams: Mimram, Colne, Beane, Misbourne, Ver, Lea, Chess, and Bulbourne.

Chalk streams are globally rare habitats made up of crystal clear, oxygen-rich water, providing a stable, cool and nutrient-rich environment supporting a rich biodiversity. 224 of the 260 rare chalk streams in the world are located in England, becoming increasingly threatened by abstraction and pollution. Wildlife supported by chalk streams include rare species such as southern chalk stream Atlantic salmon, water vole, brown trout, and water crowfoot and includes species considered to require conservation under the UK Biodiversity Action Plan (UK BAP) such as white-clawed crayfish, southern damselfly, Desmoulin’s whorl snail, freshwater pea mussel and depressed river mussel.

The ecosystems in and around the stream must be managed sensitively to ensure habitat is not lost, and the channel structure is retained. Management recommendations were made to clear obstructed channels to improve hydrology - ensuring the flow of water does not cause excessive erosion of the banks, reducing or removing overhanging vegetation to allow light to penetrate through to the river where it was found to be heavily shaded – to achieve a 70:30 ratio of light/shade, retaining shaded areas for wildlife. Deadwood habitats were retained, and riparian tree species that respond favourably to pollarding or coppicing were managed where suitable to allow light to penetrate the river and root systems to aid with retaining the river banks.

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