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Conservation Sites of Special Scientific Interest

Sites of Special Scientific Interest (SSSIs) protect the countrys most valuable wildlife and geological sites. In England alone there are over 4,000 SSSIs. They cover approximately 7% of the countrys land area and include a range of spectacular habitats including wetlands, chalk rivers, upland moorland, flower-rich meadows and upland moorland.

Many SSSI sites are also internationally important for their wildlife, and have been designated as Special Areas of Conservation (SACs), Special Protection Areas (SPAs) or Ramsar sites. Often SSSIs are also National Nature Reserves (NNRs) or Local Nature Reserves (LNRs).

SSSIs are graded to identify their condition by Natural England:

• Favourable
• Unfavourable recovering
• Unfavourable no change
• Unfavourable declining
• Part destroyed
• Destroyed

Within its management the Trust has five SSSI sites:

• Lopwell Dam
• Crowdy Reservoir
• Burrator Reservoir
• Mary Tavy
• Squabmoor

Lopwell Dam

Part of the Tamar Tavy SSSI complex this site is also designated as a Local Nature Reserve. The unit (No. 42) is designated for littoral sediment and comprises 114 hectares of which The Trust manages 1.5 hectares.

Littoral sediment is widespread around the UK and forms features such as beaches, sand banks, and intertidal mudflats. A large proportion of this habitat occurs in estuaries and inlets such as the Tamar/Tavy Estuaries.

At the extreme upper margins of the littoral zone, a typical community of undisturbed muddy sheltered areas is saltmarsh and it is this habitat that is found at Lopwell Dam. The habitat provides a transition from mudflat areas on the lower marsh, where the vegetation is frequently flooded by the tide, through to the upper saltmarsh.

Typical species found at Lopwell include common saltmarsh-grass, red fescue, sea couch, sea purslane, sea aster, sea arrowgrass, sea club-rush and English scurvygrass.

The total area for the Tamar/Tavy SSSI is 1,413 hectares, the majority of which is in a favourable condition. The Trust plans to provide improved interpretation at Lopwell which will include the area of SSSI it manages.

Crowdy Reservoir

85 hectares of water and land at Crowdy Reservoir fall into the North Bodmin Moor SSSI. The total area of this SSSI is 4,889 hectares and the area designated as unit 14 (a total of 99.72 hectares) is known as Crowdy Marsh. The unit is designated for its upland acid grassland and the site is also a Special Area of Conservation.

The SSSI unit is currently in an Unfavourable condition mainly due to overgrazing.
The Trust and South West Water have been working with the Davidstow Moor Commoners Association to rectify this problem and new fencing, along with a grazing agreement, have been arranged in order to achieve an Unfavourable Recovering condition. The site is now in a 10 year Higher Level Stewardship agreement with Natural England the site must be put in to a management agreement with Natural England.

Crowdy Marsh is a fine example of valley mire and has a mosaic of habitats including acid grassland, wet dwarf shrub, transition mire and rush dominated mire. Species found here include bogbean, purple moor-grass, common cottongrass and two species of sundew: oblong-leaved and round-leaved.

Burrator Reservoir

The SSSI designation at Burrator is for the ‘earth heritage' of the quarries located on the road leading to the dam. The whole SSSI falls within the Trust's management and it is currently in an Unfavourable Recovering condition.

The total area is 0.51 hectares and is popular with visiting geologists and for school visits. The main aim is to ensure that the quarry faces are not encroached by vegetation such as western gorse and that the site is accessible for study and enjoyment.

Mary Tavy

A small but important ‘earth heritage' designation of Cholwell Brook totaling 0.57 hectares. This area is in a Favourable condition and, like Burrator Quarries, the main objective is to ensure that the feature is not encroached by vegetation.


1.5 hectares of the land managed by SWLT at Squabmoor Reservoir falls within the East Devon Pebblebed Heaths SSSI. The designation is for Dwarf Shrub Heath and is in an Unfavourable Recovering condition. The bulk of the SSSI (1135 hectares) is managed by Clinton Devon Estates.

Updated November 2012

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