Herstmonceux SSSI

Herstmonceux is the location of one of the finest fortified manor houses in England, lying within a park dating from at least the thirteenth century. The SSSI is centred on a chain of centuries-old ponds which feed the moat. They support an unusual fen community on neutral-acidic peat, and in particular the nationally scarce milk-parsley which in East Anglia is the food plant of the spectacular swallowtail butterfly.

acta plotted the colonies of milk parsley and modelled the pattern of siltation of the ponds and the development of National Vegetation Classification communities. This enabled a management plan for partial de-silting of the ponds to be prepared and the development of the NVC communities that most often support milk-parsley.

Wet woodland with fragments of fen lies upstream of the ponds and an essential part of our work was to advise on the management of these areas to reinstate fen and buffer the high-value ponds downstream. The work is now being implemented under Higher Level Stewardship.

Summary of the proposals

The upper parts of the pond system had dried-out and major work was necessary to restore fen

It was essential to strike a balance between open water and managing the succession of plant communities to maintain the best conditions for milk-parsley