Saturday, 16 November 2013

Hickling Broad wetland restoration

John Blackburn, Upper Thurne Warden

The last phase of an exciting wetland restoration project is taking place at Norfolk Wildlife Trust’s Hickling Broad National Nature Reserve. The project is funded by the WREN Biodiversity Action Fund and is part of a long-term plan to restore, extend and improve 77 hectares of rare fen habitat within the Bure Valley Living Landscape and re-connect areas of floodplain with the Broad.

Reprofiling the old IDB dyke
NWT Hickling Broad is situated in the upper stretches of the River Thurne, and is the largest expanse of open water in the Broads. It has been managed by Norfolk Wildlife Trust since 1945 and now covers an area of approximately 600 hectares which includes the largest of the Norfolk Broads. A rich wetland mosaic includes floodplain, fen, wet woodland, open water and reed bed. The variety of habitats and the rare wildlife they support have led to this site being given a multitude of international, European and National conservation designations. 

The final phase of the wetland restoration project will see the much welcomed Landfill Community Fund grant spent on enhancing the Upper Thurne Living Landscape vision of creating a more natural functioning wetland habitat. 47 hectares of drained marsh land will be ‘re-wetted’, allowing water levels to raise to their natural level and extent. A series of shallow pools will be created or enhanced for wading birds. 2.5km of dyke will be re-profiled to enable emergent vegetation to develop,  and a further 330m of dykes that currently do not have good water flow will be restored.

Improvements and modification of grazing infrastructure including fences, gates, culverts and corrals will allow for on-going conservation grazing and site management.

Whiteslea Marshes bund to retain higher water before being full
The wider conservation project work at Hickling has involved close partnership working with many organisations including Broadland Environmental Services Limited (BESL) and the Inland Drainage Board (IDB). BESL has been involved with the managed realignment of a section of floodbank and this will facilitate a gradual transition to a more natural floodplain reconnecting the site to the broad. The IDB has worked closely with NWT realigning drains and installing new structures and water controls on the site to improve water levels and their management for biodiversity.

And with the higher water

Raising water levels on the drained marshes and installing infrastructure to facilitate the managed retreat of flood defences enables a gradual sensitive transition. This pragmatic response to the impact of climate change and sea level rise aims to create the space within which habitats and species like swallowtail butterflies can adapt and thrive into the future. Nationally scarce species such as marsh fern and greater water parsnip will also benefit from this ground-breaking work.

The on-going management of the site will involve raising water levels and then allowing the water to lower naturally, reflecting a more natural wetland system. Conservation grazing with cattle and ponies will ensure a mosaic of habitat is maintained. As stock move across the site they maintain the vegetation through grazing pressure allowing delicate species to thrive. NWT currently manage 24 Konik ponies, a breed that are especially adapted to enjoy wetter conditions.

Gadwall, photo by Steve Bond
Open water is key for overwintering wildfowl like teal and gadwall. New open water will establish and enhance the existing high wildlife value habitat found within the unreclaimed floodplain fens in Broadland. This will also add to the highly successful 100 Acre reed bed work carried out in 1999, which saw the successful breeding of bittern, an endangered and UK Priority Biodiversity Action Plan Species. The bittern has suffered notable decline due to loss of reed bed and freshwater habitat which it depends on. Its success at Hickling Broad highlights just how special the site is as reserve for wildlife. These habitats are often missing from the Upper Thurne catchment which is largely embanked and will complement the existing small areas found at Martham and around the western margin of Hickling Broad.

The project design and improvements will ensure that these fragile habitats are safeguarded for the future. All of which will reinforce existing populations of key species for their long term survival and attract larger populations of species such as bittern; common crane - one of Europe’s largest birds with a wingspan of 1.8 - 2.2m -  marsh harrier and Norfolk’s iconic swallowtail butterfly.

As well as improving the quality of the habitat for wildlife, visitors to the reserve will have a much improved experience being able to view both new and enhanced pools from the current Cadbury and Seckers Hides and Observation Hut. Raised flood banks and bunds, although modest in height will in turn elevate the visitor just enough to dramatically increase the field of view across the site.

Currently at Hickling 

A phase of the Wetland Restoration Project will mean the closure of Seckers and Cadbury bird hides until the new year. Visitors will also observe four excavators constructing bunds and culverts and bird scrapes as part to this project. This will mean that whilst the boardwalk path to the broad will remain open it will not be suitable for wheelchairs as a section has been removed to allow machinery access and replaced temporally by an earth bank, NWT apologies for any inconvenience.

For more details, please ring NWT on 01603 625540 before your visit. Thank you for your understanding.

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